diff options
Diffstat (limited to 'fs/crypto')
| -rw-r--r-- | fs/crypto/Kconfig | 38 | ||||
| -rw-r--r-- | fs/crypto/Makefile | 1 | ||||
| -rw-r--r-- | fs/crypto/bio.c | 102 | ||||
| -rw-r--r-- | fs/crypto/crypto.c | 43 | ||||
| -rw-r--r-- | fs/crypto/fname.c | 294 | ||||
| -rw-r--r-- | fs/crypto/fscrypt_private.h | 399 | ||||
| -rw-r--r-- | fs/crypto/hkdf.c | 19 | ||||
| -rw-r--r-- | fs/crypto/hooks.c | 180 | ||||
| -rw-r--r-- | fs/crypto/inline_crypt.c | 483 | ||||
| -rw-r--r-- | fs/crypto/keyring.c | 688 | ||||
| -rw-r--r-- | fs/crypto/keysetup.c | 566 | ||||
| -rw-r--r-- | fs/crypto/keysetup_v1.c | 34 | ||||
| -rw-r--r-- | fs/crypto/policy.c | 384 |
13 files changed, 2361 insertions, 870 deletions
diff --git a/fs/crypto/Kconfig b/fs/crypto/Kconfig index 8046d7c7a3e9..2d0c8922f635 100644 --- a/fs/crypto/Kconfig +++ b/fs/crypto/Kconfig @@ -4,6 +4,7 @@ config FS_ENCRYPTION select CRYPTO select CRYPTO_HASH select CRYPTO_SKCIPHER + select CRYPTO_LIB_SHA256 select KEYS help Enable encryption of files and directories. This @@ -13,14 +14,33 @@ config FS_ENCRYPTION F2FS and UBIFS make use of this feature. # Filesystems supporting encryption must select this if FS_ENCRYPTION. This -# allows the algorithms to be built as modules when all the filesystems are. +# allows the algorithms to be built as modules when all the filesystems are, +# whereas selecting them from FS_ENCRYPTION would force them to be built-in. +# +# Note: this option only pulls in the algorithms that filesystem encryption +# needs "by default". If userspace will use "non-default" encryption modes such +# as Adiantum encryption, then those other modes need to be explicitly enabled +# in the crypto API; see Documentation/filesystems/fscrypt.rst for details. +# +# Also note that this option only pulls in the generic implementations of the +# algorithms, not any per-architecture optimized implementations. It is +# strongly recommended to enable optimized implementations too. It is safe to +# disable these generic implementations if corresponding optimized +# implementations will always be available too; for this reason, these are soft +# dependencies ('imply' rather than 'select'). Only disable these generic +# implementations if you're sure they will never be needed, though. config FS_ENCRYPTION_ALGS tristate - select CRYPTO_AES - select CRYPTO_CBC - select CRYPTO_CTS - select CRYPTO_ECB - select CRYPTO_HMAC - select CRYPTO_SHA256 - select CRYPTO_SHA512 - select CRYPTO_XTS + imply CRYPTO_AES + imply CRYPTO_CBC + imply CRYPTO_CTS + imply CRYPTO_ECB + imply CRYPTO_HMAC + imply CRYPTO_SHA512 + imply CRYPTO_XTS + +config FS_ENCRYPTION_INLINE_CRYPT + bool "Enable fscrypt to use inline crypto" + depends on FS_ENCRYPTION && BLK_INLINE_ENCRYPTION + help + Enable fscrypt to use inline encryption hardware if available. diff --git a/fs/crypto/Makefile b/fs/crypto/Makefile index 232e2bb5a337..652c7180ec6d 100644 --- a/fs/crypto/Makefile +++ b/fs/crypto/Makefile @@ -11,3 +11,4 @@ fscrypto-y := crypto.o \ policy.o fscrypto-$(CONFIG_BLOCK) += bio.o +fscrypto-$(CONFIG_FS_ENCRYPTION_INLINE_CRYPT) += inline_crypt.o diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c index 4fa18fff9c4e..1b4403136d05 100644 --- a/fs/crypto/bio.c +++ b/fs/crypto/bio.c @@ -1,23 +1,10 @@ // SPDX-License-Identifier: GPL-2.0 /* - * This contains encryption functions for per-file encryption. + * Utility functions for file contents encryption/decryption on + * block device-based filesystems. * * Copyright (C) 2015, Google, Inc. * Copyright (C) 2015, Motorola Mobility - * - * Written by Michael Halcrow, 2014. - * - * Filename encryption additions - * Uday Savagaonkar, 2014 - * Encryption policy handling additions - * Ildar Muslukhov, 2014 - * Add fscrypt_pullback_bio_page() - * Jaegeuk Kim, 2015. - * - * This has not yet undergone a rigorous security audit. - * - * The usage of AES-XTS should conform to recommendations in NIST - * Special Publication 800-38E and IEEE P1619/D16. */ #include <linux/pagemap.h> @@ -26,21 +13,86 @@ #include <linux/namei.h> #include "fscrypt_private.h" -void fscrypt_decrypt_bio(struct bio *bio) +/** + * fscrypt_decrypt_bio() - decrypt the contents of a bio + * @bio: the bio to decrypt + * + * Decrypt the contents of a "read" bio following successful completion of the + * underlying disk read. The bio must be reading a whole number of blocks of an + * encrypted file directly into the page cache. If the bio is reading the + * ciphertext into bounce pages instead of the page cache (for example, because + * the file is also compressed, so decompression is required after decryption), + * then this function isn't applicable. This function may sleep, so it must be + * called from a workqueue rather than from the bio's bi_end_io callback. + * + * Return: %true on success; %false on failure. On failure, bio->bi_status is + * also set to an error status. + */ +bool fscrypt_decrypt_bio(struct bio *bio) { struct bio_vec *bv; struct bvec_iter_all iter_all; bio_for_each_segment_all(bv, bio, iter_all) { struct page *page = bv->bv_page; - int ret = fscrypt_decrypt_pagecache_blocks(page, bv->bv_len, + int err = fscrypt_decrypt_pagecache_blocks(page, bv->bv_len, bv->bv_offset); - if (ret) - SetPageError(page); + + if (err) { + bio->bi_status = errno_to_blk_status(err); + return false; + } } + return true; } EXPORT_SYMBOL(fscrypt_decrypt_bio); +static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode, + pgoff_t lblk, sector_t pblk, + unsigned int len) +{ + const unsigned int blockbits = inode->i_blkbits; + const unsigned int blocks_per_page = 1 << (PAGE_SHIFT - blockbits); + struct bio *bio; + int ret, err = 0; + int num_pages = 0; + + /* This always succeeds since __GFP_DIRECT_RECLAIM is set. */ + bio = bio_alloc(inode->i_sb->s_bdev, BIO_MAX_VECS, REQ_OP_WRITE, + GFP_NOFS); + + while (len) { + unsigned int blocks_this_page = min(len, blocks_per_page); + unsigned int bytes_this_page = blocks_this_page << blockbits; + + if (num_pages == 0) { + fscrypt_set_bio_crypt_ctx(bio, inode, lblk, GFP_NOFS); + bio->bi_iter.bi_sector = + pblk << (blockbits - SECTOR_SHIFT); + } + ret = bio_add_page(bio, ZERO_PAGE(0), bytes_this_page, 0); + if (WARN_ON(ret != bytes_this_page)) { + err = -EIO; + goto out; + } + num_pages++; + len -= blocks_this_page; + lblk += blocks_this_page; + pblk += blocks_this_page; + if (num_pages == BIO_MAX_VECS || !len || + !fscrypt_mergeable_bio(bio, inode, lblk)) { + err = submit_bio_wait(bio); + if (err) + goto out; + bio_reset(bio, inode->i_sb->s_bdev, REQ_OP_WRITE); + num_pages = 0; + } + } +out: + bio_put(bio); + return err; +} + /** * fscrypt_zeroout_range() - zero out a range of blocks in an encrypted file * @inode: the file's inode @@ -75,7 +127,11 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk, if (len == 0) return 0; - BUILD_BUG_ON(ARRAY_SIZE(pages) > BIO_MAX_PAGES); + if (fscrypt_inode_uses_inline_crypto(inode)) + return fscrypt_zeroout_range_inline_crypt(inode, lblk, pblk, + len); + + BUILD_BUG_ON(ARRAY_SIZE(pages) > BIO_MAX_VECS); nr_pages = min_t(unsigned int, ARRAY_SIZE(pages), (len + blocks_per_page - 1) >> blocks_per_page_bits); @@ -97,12 +153,10 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk, return -EINVAL; /* This always succeeds since __GFP_DIRECT_RECLAIM is set. */ - bio = bio_alloc(GFP_NOFS, nr_pages); + bio = bio_alloc(inode->i_sb->s_bdev, nr_pages, REQ_OP_WRITE, GFP_NOFS); do { - bio_set_dev(bio, inode->i_sb->s_bdev); bio->bi_iter.bi_sector = pblk << (blockbits - 9); - bio_set_op_attrs(bio, REQ_OP_WRITE, 0); i = 0; offset = 0; @@ -129,7 +183,7 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk, err = submit_bio_wait(bio); if (err) goto out; - bio_reset(bio); + bio_reset(bio, inode->i_sb->s_bdev, REQ_OP_WRITE); } while (len != 0); err = 0; out: diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index 1ecaac7ee3cb..e78be66bbf01 100644 --- a/fs/crypto/crypto.c +++ b/fs/crypto/crypto.c @@ -54,6 +54,7 @@ struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags) /** * fscrypt_free_bounce_page() - free a ciphertext bounce page + * @bounce_page: the bounce page to free, or NULL * * Free a bounce page that was allocated by fscrypt_encrypt_pagecache_blocks(), * or by fscrypt_alloc_bounce_page() directly. @@ -68,6 +69,14 @@ void fscrypt_free_bounce_page(struct page *bounce_page) } EXPORT_SYMBOL(fscrypt_free_bounce_page); +/* + * Generate the IV for the given logical block number within the given file. + * For filenames encryption, lblk_num == 0. + * + * Keep this in sync with fscrypt_limit_io_blocks(). fscrypt_limit_io_blocks() + * needs to know about any IV generation methods where the low bits of IV don't + * simply contain the lblk_num (e.g., IV_INO_LBLK_32). + */ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, const struct fscrypt_info *ci) { @@ -76,10 +85,14 @@ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, memset(iv, 0, ci->ci_mode->ivsize); if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) { - WARN_ON_ONCE((u32)lblk_num != lblk_num); + WARN_ON_ONCE(lblk_num > U32_MAX); + WARN_ON_ONCE(ci->ci_inode->i_ino > U32_MAX); lblk_num |= (u64)ci->ci_inode->i_ino << 32; + } else if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) { + WARN_ON_ONCE(lblk_num > U32_MAX); + lblk_num = (u32)(ci->ci_hashed_ino + lblk_num); } else if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) { - memcpy(iv->nonce, ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE); + memcpy(iv->nonce, ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE); } iv->lblk_num = cpu_to_le64(lblk_num); } @@ -95,12 +108,12 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw, DECLARE_CRYPTO_WAIT(wait); struct scatterlist dst, src; struct fscrypt_info *ci = inode->i_crypt_info; - struct crypto_skcipher *tfm = ci->ci_ctfm; + struct crypto_skcipher *tfm = ci->ci_enc_key.tfm; int res = 0; if (WARN_ON_ONCE(len <= 0)) return -EINVAL; - if (WARN_ON_ONCE(len % FS_CRYPTO_BLOCK_SIZE != 0)) + if (WARN_ON_ONCE(len % FSCRYPT_CONTENTS_ALIGNMENT != 0)) return -EINVAL; fscrypt_generate_iv(&iv, lblk_num, ci); @@ -132,7 +145,8 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw, } /** - * fscrypt_encrypt_pagecache_blocks() - Encrypt filesystem blocks from a pagecache page + * fscrypt_encrypt_pagecache_blocks() - Encrypt filesystem blocks from a + * pagecache page * @page: The locked pagecache page containing the block(s) to encrypt * @len: Total size of the block(s) to encrypt. Must be a nonzero * multiple of the filesystem's block size. @@ -199,8 +213,8 @@ EXPORT_SYMBOL(fscrypt_encrypt_pagecache_blocks); * fscrypt_encrypt_block_inplace() - Encrypt a filesystem block in-place * @inode: The inode to which this block belongs * @page: The page containing the block to encrypt - * @len: Size of block to encrypt. Doesn't need to be a multiple of the - * fs block size, but must be a multiple of FS_CRYPTO_BLOCK_SIZE. + * @len: Size of block to encrypt. This must be a multiple of + * FSCRYPT_CONTENTS_ALIGNMENT. * @offs: Byte offset within @page at which the block to encrypt begins * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based * number of the block within the file @@ -222,7 +236,8 @@ int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page, EXPORT_SYMBOL(fscrypt_encrypt_block_inplace); /** - * fscrypt_decrypt_pagecache_blocks() - Decrypt filesystem blocks in a pagecache page + * fscrypt_decrypt_pagecache_blocks() - Decrypt filesystem blocks in a + * pagecache page * @page: The locked pagecache page containing the block(s) to decrypt * @len: Total size of the block(s) to decrypt. Must be a nonzero * multiple of the filesystem's block size. @@ -233,7 +248,7 @@ EXPORT_SYMBOL(fscrypt_encrypt_block_inplace); * which must still be locked and not uptodate. Normally, blocksize == * PAGE_SIZE and the whole page is decrypted at once. * - * This is for use by the filesystem's ->readpages() method. + * This is for use by the filesystem's ->readahead() method. * * Return: 0 on success; -errno on failure */ @@ -268,8 +283,8 @@ EXPORT_SYMBOL(fscrypt_decrypt_pagecache_blocks); * fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place * @inode: The inode to which this block belongs * @page: The page containing the block to decrypt - * @len: Size of block to decrypt. Doesn't need to be a multiple of the - * fs block size, but must be a multiple of FS_CRYPTO_BLOCK_SIZE. + * @len: Size of block to decrypt. This must be a multiple of + * FSCRYPT_CONTENTS_ALIGNMENT. * @offs: Byte offset within @page at which the block to decrypt begins * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based * number of the block within the file @@ -336,9 +351,11 @@ void fscrypt_msg(const struct inode *inode, const char *level, va_start(args, fmt); vaf.fmt = fmt; vaf.va = &args; - if (inode) + if (inode && inode->i_ino) printk("%sfscrypt (%s, inode %lu): %pV\n", level, inode->i_sb->s_id, inode->i_ino, &vaf); + else if (inode) + printk("%sfscrypt (%s): %pV\n", level, inode->i_sb->s_id, &vaf); else printk("%sfscrypt: %pV\n", level, &vaf); va_end(args); @@ -346,6 +363,8 @@ void fscrypt_msg(const struct inode *inode, const char *level, /** * fscrypt_init() - Set up for fs encryption. + * + * Return: 0 on success; -errno on failure */ static int __init fscrypt_init(void) { diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 4c212442a8f7..12bd61d20f69 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -14,11 +14,18 @@ #include <linux/namei.h> #include <linux/scatterlist.h> #include <crypto/hash.h> -#include <crypto/sha.h> +#include <crypto/sha2.h> #include <crypto/skcipher.h> #include "fscrypt_private.h" -/** +/* + * The minimum message length (input and output length), in bytes, for all + * filenames encryption modes. Filenames shorter than this will be zero-padded + * before being encrypted. + */ +#define FSCRYPT_FNAME_MIN_MSG_LEN 16 + +/* * struct fscrypt_nokey_name - identifier for directory entry when key is absent * * When userspace lists an encrypted directory without access to the key, the @@ -26,7 +33,7 @@ * it to find the directory entry again if requested. Naively, that would just * mean using the ciphertext filenames. However, since the ciphertext filenames * can contain illegal characters ('\0' and '/'), they must be encoded in some - * way. We use base64. But that can cause names to exceed NAME_MAX (255 + * way. We use base64url. But that can cause names to exceed NAME_MAX (255 * bytes), so we also need to use a strong hash to abbreviate long names. * * The filesystem may also need another kind of hash, the "dirhash", to quickly @@ -38,7 +45,7 @@ * casefolded directories use this type of dirhash. At least in these cases, * each no-key name must include the name's dirhash too. * - * To meet all these requirements, we base64-encode the following + * To meet all these requirements, we base64url-encode the following * variable-length structure. It contains the dirhash, or 0's if the filesystem * didn't provide one; up to 149 bytes of the ciphertext name; and for * ciphertexts longer than 149 bytes, also the SHA-256 of the remaining bytes. @@ -52,45 +59,18 @@ struct fscrypt_nokey_name { u32 dirhash[2]; u8 bytes[149]; u8 sha256[SHA256_DIGEST_SIZE]; -}; /* 189 bytes => 252 bytes base64-encoded, which is <= NAME_MAX (255) */ +}; /* 189 bytes => 252 bytes base64url-encoded, which is <= NAME_MAX (255) */ /* - * Decoded size of max-size nokey name, i.e. a name that was abbreviated using + * Decoded size of max-size no-key name, i.e. a name that was abbreviated using * the strong hash and thus includes the 'sha256' field. This isn't simply * sizeof(struct fscrypt_nokey_name), as the padding at the end isn't included. */ #define FSCRYPT_NOKEY_NAME_MAX offsetofend(struct fscrypt_nokey_name, sha256) -static struct crypto_shash *sha256_hash_tfm; - -static int fscrypt_do_sha256(const u8 *data, unsigned int data_len, u8 *result) -{ - struct crypto_shash *tfm = READ_ONCE(sha256_hash_tfm); - - if (unlikely(!tfm)) { - struct crypto_shash *prev_tfm; - - tfm = crypto_alloc_shash("sha256", 0, 0); - if (IS_ERR(tfm)) { - fscrypt_err(NULL, - "Error allocating SHA-256 transform: %ld", - PTR_ERR(tfm)); - return PTR_ERR(tfm); - } - prev_tfm = cmpxchg(&sha256_hash_tfm, NULL, tfm); - if (prev_tfm) { - crypto_free_shash(tfm); - tfm = prev_tfm; - } - } - { - SHASH_DESC_ON_STACK(desc, tfm); - - desc->tfm = tfm; - - return crypto_shash_digest(desc, data, data_len, result); - } -} +/* Encoded size of max-size no-key name */ +#define FSCRYPT_NOKEY_NAME_MAX_ENCODED \ + FSCRYPT_BASE64URL_CHARS(FSCRYPT_NOKEY_NAME_MAX) static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) { @@ -105,9 +85,13 @@ static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) /** * fscrypt_fname_encrypt() - encrypt a filename - * - * The output buffer must be at least as large as the input buffer. - * Any extra space is filled with NUL padding before encryption. + * @inode: inode of the parent directory (for regular filenames) + * or of the symlink (for symlink targets). Key must already be + * set up. + * @iname: the filename to encrypt + * @out: (output) the encrypted filename + * @olen: size of the encrypted filename. It must be at least @iname->len. + * Any extra space is filled with NUL padding before encryption. * * Return: 0 on success, -errno on failure */ @@ -117,7 +101,7 @@ int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname, struct skcipher_request *req = NULL; DECLARE_CRYPTO_WAIT(wait); const struct fscrypt_info *ci = inode->i_crypt_info; - struct crypto_skcipher *tfm = ci->ci_ctfm; + struct crypto_skcipher *tfm = ci->ci_enc_key.tfm; union fscrypt_iv iv; struct scatterlist sg; int res; @@ -154,11 +138,15 @@ int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname, return 0; } +EXPORT_SYMBOL_GPL(fscrypt_fname_encrypt); /** * fname_decrypt() - decrypt a filename - * - * The caller must have allocated sufficient memory for the @oname string. + * @inode: inode of the parent directory (for regular filenames) + * or of the symlink (for symlink targets) + * @iname: the encrypted filename to decrypt + * @oname: (output) the decrypted filename. The caller must have allocated + * enough space for this, e.g. using fscrypt_fname_alloc_buffer(). * * Return: 0 on success, -errno on failure */ @@ -170,7 +158,7 @@ static int fname_decrypt(const struct inode *inode, DECLARE_CRYPTO_WAIT(wait); struct scatterlist src_sg, dst_sg; const struct fscrypt_info *ci = inode->i_crypt_info; - struct crypto_skcipher *tfm = ci->ci_ctfm; + struct crypto_skcipher *tfm = ci->ci_enc_key.tfm; union fscrypt_iv iv; int res; @@ -200,93 +188,139 @@ static int fname_decrypt(const struct inode *inode, return 0; } -static const char lookup_table[65] = - "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; +static const char base64url_table[65] = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; -#define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3) +#define FSCRYPT_BASE64URL_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3) /** - * base64_encode() - + * fscrypt_base64url_encode() - base64url-encode some binary data + * @src: the binary data to encode + * @srclen: the length of @src in bytes + * @dst: (output) the base64url-encoded string. Not NUL-terminated. * - * Encodes the input string using characters from the set [A-Za-z0-9+,]. - * The encoded string is roughly 4/3 times the size of the input string. + * Encodes data using base64url encoding, i.e. the "Base 64 Encoding with URL + * and Filename Safe Alphabet" specified by RFC 4648. '='-padding isn't used, + * as it's unneeded and not required by the RFC. base64url is used instead of + * base64 to avoid the '/' character, which isn't allowed in filenames. * - * Return: length of the encoded string + * Return: the length of the resulting base64url-encoded string in bytes. + * This will be equal to FSCRYPT_BASE64URL_CHARS(srclen). */ -static int base64_encode(const u8 *src, int len, char *dst) +static int fscrypt_base64url_encode(const u8 *src, int srclen, char *dst) { - int i, bits = 0, ac = 0; + u32 ac = 0; + int bits = 0; + int i; char *cp = dst; - for (i = 0; i < len; i++) { - ac += src[i] << bits; + for (i = 0; i < srclen; i++) { + ac = (ac << 8) | src[i]; bits += 8; do { - *cp++ = lookup_table[ac & 0x3f]; - ac >>= 6; bits -= 6; + *cp++ = base64url_table[(ac >> bits) & 0x3f]; } while (bits >= 6); } if (bits) - *cp++ = lookup_table[ac & 0x3f]; + *cp++ = base64url_table[(ac << (6 - bits)) & 0x3f]; return cp - dst; } -static int base64_decode(const char *src, int len, u8 *dst) +/** + * fscrypt_base64url_decode() - base64url-decode a string + * @src: the string to decode. Doesn't need to be NUL-terminated. + * @srclen: the length of @src in bytes + * @dst: (output) the decoded binary data + * + * Decodes a string using base64url encoding, i.e. the "Base 64 Encoding with + * URL and Filename Safe Alphabet" specified by RFC 4648. '='-padding isn't + * accepted, nor are non-encoding characters such as whitespace. + * + * This implementation hasn't been optimized for performance. + * + * Return: the length of the resulting decoded binary data in bytes, + * or -1 if the string isn't a valid base64url string. + */ +static int fscrypt_base64url_decode(const char *src, int srclen, u8 *dst) { - int i, bits = 0, ac = 0; - const char *p; - u8 *cp = dst; + u32 ac = 0; + int bits = 0; + int i; + u8 *bp = dst; + + for (i = 0; i < srclen; i++) { + const char *p = strchr(base64url_table, src[i]); - for (i = 0; i < len; i++) { - p = strchr(lookup_table, src[i]); if (p == NULL || src[i] == 0) - return -2; - ac += (p - lookup_table) << bits; + return -1; + ac = (ac << 6) | (p - base64url_table); bits += 6; if (bits >= 8) { - *cp++ = ac & 0xff; - ac >>= 8; bits -= 8; + *bp++ = (u8)(ac >> bits); } } - if (ac) + if (ac & ((1 << bits) - 1)) return -1; - return cp - dst; + return bp - dst; } -bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len, - u32 max_len, u32 *encrypted_len_ret) +bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, + u32 orig_len, u32 max_len, + u32 *encrypted_len_ret) { - const struct fscrypt_info *ci = inode->i_crypt_info; - int padding = 4 << (fscrypt_policy_flags(&ci->ci_policy) & + int padding = 4 << (fscrypt_policy_flags(policy) & FSCRYPT_POLICY_FLAGS_PAD_MASK); u32 encrypted_len; if (orig_len > max_len) return false; - encrypted_len = max(orig_len, (u32)FS_CRYPTO_BLOCK_SIZE); + encrypted_len = max_t(u32, orig_len, FSCRYPT_FNAME_MIN_MSG_LEN); encrypted_len = round_up(encrypted_len, padding); *encrypted_len_ret = min(encrypted_len, max_len); return true; } /** - * fscrypt_fname_alloc_buffer - allocate a buffer for presented filenames + * fscrypt_fname_encrypted_size() - calculate length of encrypted filename + * @inode: parent inode of dentry name being encrypted. Key must + * already be set up. + * @orig_len: length of the original filename + * @max_len: maximum length to return + * @encrypted_len_ret: where calculated length should be returned (on success) + * + * Filenames that are shorter than the maximum length may have their lengths + * increased slightly by encryption, due to padding that is applied. + * + * Return: false if the orig_len is greater than max_len. Otherwise, true and + * fill out encrypted_len_ret with the length (up to max_len). + */ +bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len, + u32 max_len, u32 *encrypted_len_ret) +{ + return __fscrypt_fname_encrypted_size(&inode->i_crypt_info->ci_policy, + orig_len, max_len, + encrypted_len_ret); +} +EXPORT_SYMBOL_GPL(fscrypt_fname_encrypted_size); + +/** + * fscrypt_fname_alloc_buffer() - allocate a buffer for presented filenames + * @max_encrypted_len: maximum length of encrypted filenames the buffer will be + * used to present + * @crypto_str: (output) buffer to allocate * * Allocate a buffer that is large enough to hold any decrypted or encoded * filename (null-terminated), for the given maximum encrypted filename length. * * Return: 0 on success, -errno on failure */ -int fscrypt_fname_alloc_buffer(const struct inode *inode, - u32 max_encrypted_len, +int fscrypt_fname_alloc_buffer(u32 max_encrypted_len, struct fscrypt_str *crypto_str) { - const u32 max_encoded_len = BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX); - u32 max_presented_len; - - max_presented_len = max(max_encoded_len, max_encrypted_len); + u32 max_presented_len = max_t(u32, FSCRYPT_NOKEY_NAME_MAX_ENCODED, + max_encrypted_len); crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS); if (!crypto_str->name) @@ -297,9 +331,10 @@ int fscrypt_fname_alloc_buffer(const struct inode *inode, EXPORT_SYMBOL(fscrypt_fname_alloc_buffer); /** - * fscrypt_fname_free_buffer - free the buffer for presented filenames + * fscrypt_fname_free_buffer() - free a buffer for presented filenames + * @crypto_str: the buffer to free * - * Free the buffer allocated by fscrypt_fname_alloc_buffer(). + * Free a buffer that was allocated by fscrypt_fname_alloc_buffer(). */ void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) { @@ -311,10 +346,19 @@ void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) EXPORT_SYMBOL(fscrypt_fname_free_buffer); /** - * fscrypt_fname_disk_to_usr() - converts a filename from disk space to user - * space - * - * The caller must have allocated sufficient memory for the @oname string. + * fscrypt_fname_disk_to_usr() - convert an encrypted filename to + * user-presentable form + * @inode: inode of the parent directory (for regular filenames) + * or of the symlink (for symlink targets) + * @hash: first part of the name's dirhash, if applicable. This only needs to + * be provided if the filename is located in an indexed directory whose + * encryption key may be unavailable. Not needed for symlink targets. + * @minor_hash: second part of the name's dirhash, if applicable + * @iname: encrypted filename to convert. May also be "." or "..", which + * aren't actually encrypted. + * @oname: output buffer for the user-presentable filename. The caller must + * have allocated enough space for this, e.g. using + * fscrypt_fname_alloc_buffer(). * * If the key is available, we'll decrypt the disk name. Otherwise, we'll * encode it for presentation in fscrypt_nokey_name format. @@ -330,7 +374,6 @@ int fscrypt_fname_disk_to_usr(const struct inode *inode, const struct qstr qname = FSTR_TO_QSTR(iname); struct fscrypt_nokey_name nokey_name; u32 size; /* size of the unencoded no-key name */ - int err; if (fscrypt_is_dot_dotdot(&qname)) { oname->name[0] = '.'; @@ -339,7 +382,7 @@ int fscrypt_fname_disk_to_usr(const struct inode *inode, return 0; } - if (iname->len < FS_CRYPTO_BLOCK_SIZE) + if (iname->len < FSCRYPT_FNAME_MIN_MSG_LEN) return -EUCLEAN; if (fscrypt_has_encryption_key(inode)) @@ -353,29 +396,24 @@ int fscrypt_fname_disk_to_usr(const struct inode *inode, offsetof(struct fscrypt_nokey_name, bytes)); BUILD_BUG_ON(offsetofend(struct fscrypt_nokey_name, bytes) != offsetof(struct fscrypt_nokey_name, sha256)); - BUILD_BUG_ON(BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX) > NAME_MAX); + BUILD_BUG_ON(FSCRYPT_NOKEY_NAME_MAX_ENCODED > NAME_MAX); + + nokey_name.dirhash[0] = hash; + nokey_name.dirhash[1] = minor_hash; - if (hash) { - nokey_name.dirhash[0] = hash; - nokey_name.dirhash[1] = minor_hash; - } else { - nokey_name.dirhash[0] = 0; - nokey_name.dirhash[1] = 0; - } if (iname->len <= sizeof(nokey_name.bytes)) { memcpy(nokey_name.bytes, iname->name, iname->len); size = offsetof(struct fscrypt_nokey_name, bytes[iname->len]); } else { memcpy(nokey_name.bytes, iname->name, sizeof(nokey_name.bytes)); /* Compute strong hash of remaining part of name. */ - err = fscrypt_do_sha256(&iname->name[sizeof(nokey_name.bytes)], - iname->len - sizeof(nokey_name.bytes), - nokey_name.sha256); - if (err) - return err; + sha256(&iname->name[sizeof(nokey_name.bytes)], + iname->len - sizeof(nokey_name.bytes), + nokey_name.sha256); size = FSCRYPT_NOKEY_NAME_MAX; } - oname->len = base64_encode((const u8 *)&nokey_name, size, oname->name); + oname->len = fscrypt_base64url_encode((const u8 *)&nokey_name, size, + oname->name); return 0; } EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); @@ -395,9 +433,9 @@ EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); * directory's encryption key, then @iname is the plaintext, so we encrypt it to * get the disk_name. * - * Else, for keyless @lookup operations, @iname is the presented ciphertext, so - * we decode it to get the fscrypt_nokey_name. Non-@lookup operations will be - * impossible in this case, so we fail them with ENOKEY. + * Else, for keyless @lookup operations, @iname should be a no-key name, so we + * decode it to get the struct fscrypt_nokey_name. Non-@lookup operations will + * be impossible in this case, so we fail them with ENOKEY. * * If successful, fscrypt_free_filename() must be called later to clean up. * @@ -417,13 +455,12 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, fname->disk_name.len = iname->len; return 0; } - ret = fscrypt_get_encryption_info(dir); + ret = fscrypt_get_encryption_info(dir, lookup); if (ret) return ret; if (fscrypt_has_encryption_key(dir)) { - if (!fscrypt_fname_encrypted_size(dir, iname->len, - dir->i_sb->s_cop->max_namelen, + if (!fscrypt_fname_encrypted_size(dir, iname->len, NAME_MAX, &fname->crypto_buf.len)) return -ENAMETOOLONG; fname->crypto_buf.name = kmalloc(fname->crypto_buf.len, @@ -441,21 +478,22 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, } if (!lookup) return -ENOKEY; - fname->is_ciphertext_name = true; + fname->is_nokey_name = true; /* * We don't have the key and we are doing a lookup; decode the * user-supplied name */ - if (iname->len > BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX)) + if (iname->len > FSCRYPT_NOKEY_NAME_MAX_ENCODED) return -ENOENT; fname->crypto_buf.name = kmalloc(FSCRYPT_NOKEY_NAME_MAX, GFP_KERNEL); if (fname->crypto_buf.name == NULL) return -ENOMEM; - ret = base64_decode(iname->name, iname->len, fname->crypto_buf.name); + ret = fscrypt_base64url_decode(iname->name, iname->len, + fname->crypto_buf.name); if (ret < (int)offsetof(struct fscrypt_nokey_name, bytes[1]) || (ret > offsetof(struct fscrypt_nokey_name, sha256) && ret != FSCRYPT_NOKEY_NAME_MAX)) { @@ -500,7 +538,7 @@ bool fscrypt_match_name(const struct fscrypt_name *fname, { const struct fscrypt_nokey_name *nokey_name = (const void *)fname->crypto_buf.name; - u8 sha256[SHA256_DIGEST_SIZE]; + u8 digest[SHA256_DIGEST_SIZE]; if (likely(fname->disk_name.name)) { if (de_name_len != fname->disk_name.len) @@ -511,10 +549,9 @@ bool fscrypt_match_name(const struct fscrypt_name *fname, return false; if (memcmp(de_name, nokey_name->bytes, sizeof(nokey_name->bytes))) return false; - if (fscrypt_do_sha256(&de_name[sizeof(nokey_name->bytes)], - de_name_len - sizeof(nokey_name->bytes), sha256)) - return false; - return !memcmp(sha256, nokey_name->sha256, sizeof(sha256)); + sha256(&de_name[sizeof(nokey_name->bytes)], + de_name_len - sizeof(nokey_name->bytes), digest); + return !memcmp(digest, nokey_name->sha256, sizeof(digest)); } EXPORT_SYMBOL_GPL(fscrypt_match_name); @@ -543,7 +580,7 @@ EXPORT_SYMBOL_GPL(fscrypt_fname_siphash); * Validate dentries in encrypted directories to make sure we aren't potentially * caching stale dentries after a key has been added. */ -static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) +int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) { struct dentry *dir; int err; @@ -551,17 +588,17 @@ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) /* * Plaintext names are always valid, since fscrypt doesn't support - * reverting to ciphertext names without evicting the directory's inode + * reverting to no-key names without evicting the directory's inode * -- which implies eviction of the dentries in the directory. */ - if (!(dentry->d_flags & DCACHE_ENCRYPTED_NAME)) + if (!(dentry->d_flags & DCACHE_NOKEY_NAME)) return 1; /* - * Ciphertext name; valid if the directory's key is still unavailable. + * No-key name; valid if the directory's key is still unavailable. * - * Although fscrypt forbids rename() on ciphertext names, we still must - * use dget_parent() here rather than use ->d_parent directly. That's + * Although fscrypt forbids rename() on no-key names, we still must use + * dget_parent() here rather than use ->d_parent directly. That's * because a corrupted fs image may contain directory hard links, which * the VFS handles by moving the directory's dentry tree in the dcache * each time ->lookup() finds the directory and it already has a dentry @@ -573,7 +610,11 @@ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) return -ECHILD; dir = dget_parent(dentry); - err = fscrypt_get_encryption_info(d_inode(dir)); + /* + * Pass allow_unsupported=true, so that files with an unsupported + * encryption policy can be deleted. + */ + err = fscrypt_get_encryption_info(d_inode(dir), true); valid = !fscrypt_has_encryption_key(d_inode(dir)); dput(dir); @@ -582,7 +623,4 @@ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) return valid; } - -const struct dentry_operations fscrypt_d_ops = { - .d_revalidate = fscrypt_d_revalidate, -}; +EXPORT_SYMBOL_GPL(fscrypt_d_revalidate); diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index 9aae851409e5..d5f68a0c5d15 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -14,23 +14,32 @@ #include <linux/fscrypt.h> #include <linux/siphash.h> #include <crypto/hash.h> +#include <linux/blk-crypto.h> #define CONST_STRLEN(str) (sizeof(str) - 1) -#define FS_KEY_DERIVATION_NONCE_SIZE 16 +#define FSCRYPT_FILE_NONCE_SIZE 16 -#define FSCRYPT_MIN_KEY_SIZE 16 +/* + * Minimum size of an fscrypt master key. Note: a longer key will be required + * if ciphers with a 256-bit security strength are used. This is just the + * absolute minimum, which applies when only 128-bit encryption is used. + */ +#define FSCRYPT_MIN_KEY_SIZE 16 #define FSCRYPT_CONTEXT_V1 1 #define FSCRYPT_CONTEXT_V2 2 +/* Keep this in sync with include/uapi/linux/fscrypt.h */ +#define FSCRYPT_MODE_MAX FSCRYPT_MODE_AES_256_HCTR2 + struct fscrypt_context_v1 { u8 version; /* FSCRYPT_CONTEXT_V1 */ u8 contents_encryption_mode; u8 filenames_encryption_mode; u8 flags; u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE]; - u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE]; + u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; }; struct fscrypt_context_v2 { @@ -40,10 +49,10 @@ struct fscrypt_context_v2 { u8 flags; u8 __reserved[4]; u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]; - u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE]; + u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; }; -/** +/* * fscrypt_context - the encryption context of an inode * * This is the on-disk equivalent of an fscrypt_policy, stored alongside each @@ -76,7 +85,26 @@ static inline int fscrypt_context_size(const union fscrypt_context *ctx) return 0; } -#undef fscrypt_policy +/* Check whether an fscrypt_context has a recognized version number and size */ +static inline bool fscrypt_context_is_valid(const union fscrypt_context *ctx, + int ctx_size) +{ + return ctx_size >= 1 && ctx_size == fscrypt_context_size(ctx); +} + +/* Retrieve the context's nonce, assuming the context was already validated */ +static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx) +{ + switch (ctx->version) { + case FSCRYPT_CONTEXT_V1: + return ctx->v1.nonce; + case FSCRYPT_CONTEXT_V2: + return ctx->v2.nonce; + } + WARN_ON(1); + return NULL; +} + union fscrypt_policy { u8 version; struct fscrypt_policy_v1 v1; @@ -137,7 +165,7 @@ fscrypt_policy_flags(const union fscrypt_policy *policy) BUG(); } -/** +/* * For encrypted symlinks, the ciphertext length is stored at the beginning * of the string in little-endian format. */ @@ -146,6 +174,20 @@ struct fscrypt_symlink_data { char encrypted_path[1]; } __packed; +/** + * struct fscrypt_prepared_key - a key prepared for actual encryption/decryption + * @tfm: crypto API transform object + * @blk_key: key for blk-crypto + * + * Normally only one of the fields will be non-NULL. + */ +struct fscrypt_prepared_key { + struct crypto_skcipher *tfm; +#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT + struct blk_crypto_key *blk_key; +#endif +}; + /* * fscrypt_info - the "encryption key" for an inode * @@ -155,12 +197,20 @@ struct fscrypt_symlink_data { */ struct fscrypt_info { - /* The actual crypto transform used for encryption and decryption */ - struct crypto_skcipher *ci_ctfm; + /* The key in a form prepared for actual encryption/decryption */ + struct fscrypt_prepared_key ci_enc_key; - /* True if the key should be freed when this fscrypt_info is freed */ + /* True if ci_enc_key should be freed when this fscrypt_info is freed */ bool ci_owns_key; +#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT + /* + * True if this inode will use inline encryption (blk-crypto) instead of + * the traditional filesystem-layer encryption. + */ + bool ci_inlinecrypt; +#endif + /* * Encryption mode used for this inode. It corresponds to either the * contents or filenames encryption mode, depending on the inode type. @@ -175,7 +225,7 @@ struct fscrypt_info { * will be NULL if the master key was found in a process-subscribed * keyring rather than in the filesystem-level keyring. */ - struct key *ci_master_key; + struct fscrypt_master_key *ci_master_key; /* * Link in list of inodes that were unlocked with the master key. @@ -185,7 +235,7 @@ struct fscrypt_info { /* * If non-NULL, then encryption is done using the master key directly - * and ci_ctfm will equal ci_direct_key->dk_ctfm. + * and ci_enc_key will equal ci_direct_key->dk_key. */ struct fscrypt_direct_key *ci_direct_key; @@ -201,7 +251,10 @@ struct fscrypt_info { union fscrypt_policy ci_policy; /* This inode's nonce, copied from the fscrypt_context */ - u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE]; + u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE]; + + /* Hashed inode number. Only set for IV_INO_LBLK_32 */ + u32 ci_hashed_ino; }; typedef enum { @@ -211,15 +264,14 @@ typedef enum { /* crypto.c */ extern struct kmem_cache *fscrypt_info_cachep; -extern int fscrypt_initialize(unsigned int cop_flags); -extern int fscrypt_crypt_block(const struct inode *inode, - fscrypt_direction_t rw, u64 lblk_num, - struct page *src_page, struct page *dest_page, - unsigned int len, unsigned int offs, - gfp_t gfp_flags); -extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags); - -extern void __printf(3, 4) __cold +int fscrypt_initialize(unsigned int cop_flags); +int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw, + u64 lblk_num, struct page *src_page, + struct page *dest_page, unsigned int len, + unsigned int offs, gfp_t gfp_flags); +struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags); + +void __printf(3, 4) __cold fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...); #define fscrypt_warn(inode, fmt, ...) \ @@ -235,31 +287,27 @@ union fscrypt_iv { __le64 lblk_num; /* per-file nonce; only set in DIRECT_KEY mode */ - u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE]; + u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; }; u8 raw[FSCRYPT_MAX_IV_SIZE]; + __le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)]; }; void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, const struct fscrypt_info *ci); /* fname.c */ -extern int fscrypt_fname_encrypt(const struct inode *inode, - const struct qstr *iname, - u8 *out, unsigned int olen); -extern bool fscrypt_fname_encrypted_size(const struct inode *inode, - u32 orig_len, u32 max_len, - u32 *encrypted_len_ret); -extern const struct dentry_operations fscrypt_d_ops; +bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, + u32 orig_len, u32 max_len, + u32 *encrypted_len_ret); /* hkdf.c */ - struct fscrypt_hkdf { struct crypto_shash *hmac_tfm; }; -extern int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key, - unsigned int master_key_size); +int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key, + unsigned int master_key_size); /* * The list of contexts in which fscrypt uses HKDF. These values are used as @@ -268,17 +316,93 @@ extern int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key, * outputs are unique and cryptographically isolated, i.e. knowledge of one * output doesn't reveal another. */ -#define HKDF_CONTEXT_KEY_IDENTIFIER 1 -#define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 -#define HKDF_CONTEXT_DIRECT_KEY 3 -#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 -#define HKDF_CONTEXT_DIRHASH_KEY 5 +#define HKDF_CONTEXT_KEY_IDENTIFIER 1 /* info=<empty> */ +#define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 /* info=file_nonce */ +#define HKDF_CONTEXT_DIRECT_KEY 3 /* info=mode_num */ +#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 /* info=mode_num||fs_uuid */ +#define HKDF_CONTEXT_DIRHASH_KEY 5 /* info=file_nonce */ +#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY 6 /* info=mode_num||fs_uuid */ +#define HKDF_CONTEXT_INODE_HASH_KEY 7 /* info=<empty> */ + +int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context, + const u8 *info, unsigned int infolen, + u8 *okm, unsigned int okmlen); + +void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf); + +/* inline_crypt.c */ +#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT +int fscrypt_select_encryption_impl(struct fscrypt_info *ci); + +static inline bool +fscrypt_using_inline_encryption(const struct fscrypt_info *ci) +{ + return ci->ci_inlinecrypt; +} + +int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, + const u8 *raw_key, + const struct fscrypt_info *ci); + +void fscrypt_destroy_inline_crypt_key(struct super_block *sb, + struct fscrypt_prepared_key *prep_key); + +/* + * Check whether the crypto transform or blk-crypto key has been allocated in + * @prep_key, depending on which encryption implementation the file will use. + */ +static inline bool +fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key, + const struct fscrypt_info *ci) +{ + /* + * The two smp_load_acquire()'s here pair with the smp_store_release()'s + * in fscrypt_prepare_inline_crypt_key() and fscrypt_prepare_key(). + * I.e., in some cases (namely, if this prep_key is a per-mode + * encryption key) another task can publish blk_key or tfm concurrently, + * executing a RELEASE barrier. We need to use smp_load_acquire() here + * to safely ACQUIRE the memory the other task published. + */ + if (fscrypt_using_inline_encryption(ci)) + return smp_load_acquire(&prep_key->blk_key) != NULL; + return smp_load_acquire(&prep_key->tfm) != NULL; +} + +#else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ + +static inline int fscrypt_select_encryption_impl(struct fscrypt_info *ci) +{ + return 0; +} + +static inline bool +fscrypt_using_inline_encryption(const struct fscrypt_info *ci) +{ + return false; +} -extern int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context, - const u8 *info, unsigned int infolen, - u8 *okm, unsigned int okmlen); +static inline int +fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, + const u8 *raw_key, + const struct fscrypt_info *ci) +{ + WARN_ON(1); + return -EOPNOTSUPP; +} -extern void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf); +static inline void +fscrypt_destroy_inline_crypt_key(struct super_block *sb, + struct fscrypt_prepared_key *prep_key) +{ +} + +static inline bool +fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key, + const struct fscrypt_info *ci) +{ + return smp_load_acquire(&prep_key->tfm) != NULL; +} +#endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ /* keyring.c */ @@ -293,7 +417,11 @@ struct fscrypt_master_key_secret { */ struct fscrypt_hkdf hkdf; - /* Size of the raw key in bytes. Set even if ->raw isn't set. */ + /* + * Size of the raw key in bytes. This remains set even if ->raw was + * zeroized due to no longer being needed. I.e. we still remember the + * size of the key even if we don't need to remember the key itself. + */ u32 size; /* For v1 policy keys: the raw key. Wiped for v2 policy keys. */ @@ -311,6 +439,40 @@ struct fscrypt_master_key_secret { struct fscrypt_master_key { /* + * Back-pointer to the super_block of the filesystem to which this + * master key has been added. Only valid if ->mk_active_refs > 0. + */ + struct super_block *mk_sb; + + /* + * Link in ->mk_sb->s_master_keys->key_hashtable. + * Only valid if ->mk_active_refs > 0. + */ + struct hlist_node mk_node; + + /* Semaphore that protects ->mk_secret and ->mk_users */ + struct rw_semaphore mk_sem; + + /* + * Active and structural reference counts. An active ref guarantees + * that the struct continues to exist, continues to be in the keyring + * ->mk_sb->s_master_keys, and that any embedded subkeys (e.g. + * ->mk_direct_keys) that have been prepared continue to exist. + * A structural ref only guarantees that the struct continues to exist. + * + * There is one active ref associated with ->mk_secret being present, + * and one active ref for each inode in ->mk_decrypted_inodes. + * + * There is one structural ref associated with the active refcount being + * nonzero. Finding a key in the keyring also takes a structural ref, + * which is then held temporarily while the key is operated on. + */ + refcount_t mk_active_refs; + refcount_t mk_struct_refs; + + struct rcu_head mk_rcu_head; + + /* * The secret key material. After FS_IOC_REMOVE_ENCRYPTION_KEY is * executed, this is wiped and no new inodes can be unlocked with this * key; however, there may still be inodes in ->mk_decrypted_inodes @@ -318,16 +480,12 @@ struct fscrypt_master_key { * FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or * FS_IOC_ADD_ENCRYPTION_KEY can add the secret again. * - * Locking: protected by key->sem (outer) and mk_secret_sem (inner). - * The reason for two locks is that key->sem also protects modifying - * mk_users, which ranks it above the semaphore for the keyring key - * type, which is in turn above page faults (via keyring_read). But - * sometimes filesystems call fscrypt_get_encryption_info() from within - * a transaction, which ranks it below page faults. So we need a - * separate lock which protects mk_secret but not also mk_users. + * While ->mk_secret is present, one ref in ->mk_active_refs is held. + * + * Locking: protected by ->mk_sem. The manipulation of ->mk_active_refs + * associated with this field is protected by ->mk_sem as well. */ struct fscrypt_master_key_secret mk_secret; - struct rw_semaphore mk_secret_sem; /* * For v1 policy keys: an arbitrary key descriptor which was assigned by @@ -346,37 +504,30 @@ struct fscrypt_master_key { * * This is NULL for v1 policy keys; those can only be added by root. * - * Locking: in addition to this keyrings own semaphore, this is - * protected by the master key's key->sem, so we can do atomic - * search+insert. It can also be searched without taking any locks, but - * in that case the returned key may have already been removed. + * Locking: protected by ->mk_sem. (We don't just rely on the keyrings + * subsystem semaphore ->mk_users->sem, as we need support for atomic + * search+insert along with proper synchronization with ->mk_secret.) */ struct key *mk_users; /* - * Length of ->mk_decrypted_inodes, plus one if mk_secret is present. - * Once this goes to 0, the master key is removed from ->s_master_keys. - * The 'struct fscrypt_master_key' will continue to live as long as the - * 'struct key' whose payload it is, but we won't let this reference - * count rise again. - */ - refcount_t mk_refcount; - - /* * List of inodes that were unlocked using this key. This allows the * inodes to be evicted efficiently if the key is removed. */ struct list_head mk_decrypted_inodes; spinlock_t mk_decrypted_inodes_lock; - /* Crypto API transforms for DIRECT_KEY policies, allocated on-demand */ - struct crypto_skcipher *mk_direct_tfms[__FSCRYPT_MODE_MAX + 1]; - /* - * Crypto API transforms for filesystem-layer implementation of - * IV_INO_LBLK_64 policies, allocated on-demand. + * Per-mode encryption keys for the various types of encryption policies + * that use them. Allocated and derived on-demand. */ - struct crypto_skcipher *mk_iv_ino_lblk_64_tfms[__FSCRYPT_MODE_MAX + 1]; + struct fscrypt_prepared_key mk_direct_keys[FSCRYPT_MODE_MAX + 1]; + struct fscrypt_prepared_key mk_iv_ino_lblk_64_keys[FSCRYPT_MODE_MAX + 1]; + struct fscrypt_prepared_key mk_iv_ino_lblk_32_keys[FSCRYPT_MODE_MAX + 1]; + + /* Hash key for inode numbers. Initialized only when needed. */ + siphash_key_t mk_ino_hash_key; + bool mk_ino_hash_key_initialized; } __randomize_layout; @@ -384,11 +535,11 @@ static inline bool is_master_key_secret_present(const struct fscrypt_master_key_secret *secret) { /* - * The READ_ONCE() is only necessary for fscrypt_drop_inode() and - * fscrypt_key_describe(). These run in atomic context, so they can't - * take ->mk_secret_sem and thus 'secret' can change concurrently which - * would be a data race. But they only need to know whether the secret - * *was* present at the time of check, so READ_ONCE() suffices. + * The READ_ONCE() is only necessary for fscrypt_drop_inode(). + * fscrypt_drop_inode() runs in atomic context, so it can't take the key + * semaphore and thus 'secret' can change concurrently which would be a + * data race. But fscrypt_drop_inode() only need to know whether the + * secret *was* present at the time of check, so READ_ONCE() suffices. */ return READ_ONCE(secret->size) != 0; } @@ -416,54 +567,100 @@ static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec) return 0; } -extern struct key * +void fscrypt_put_master_key(struct fscrypt_master_key *mk); + +void fscrypt_put_master_key_activeref(struct fscrypt_master_key *mk); + +struct fscrypt_master_key * fscrypt_find_master_key(struct super_block *sb, const struct fscrypt_key_specifier *mk_spec); -extern int fscrypt_verify_key_added(struct super_block *sb, - const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); +int fscrypt_get_test_dummy_key_identifier( + u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); + +int fscrypt_verify_key_added(struct super_block *sb, + const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); -extern int __init fscrypt_init_keyring(void); +int __init fscrypt_init_keyring(void); /* keysetup.c */ struct fscrypt_mode { const char *friendly_name; const char *cipher_str; - int keysize; - int ivsize; - int logged_impl_name; + int keysize; /* key size in bytes */ + int security_strength; /* security strength in bytes */ + int ivsize; /* IV size in bytes */ + int logged_cryptoapi_impl; + int logged_blk_crypto_native; + int logged_blk_crypto_fallback; + enum blk_crypto_mode_num blk_crypto_mode; }; extern struct fscrypt_mode fscrypt_modes[]; -extern struct crypto_skcipher * -fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key, - const struct inode *inode); +int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key, + const u8 *raw_key, const struct fscrypt_info *ci); + +void fscrypt_destroy_prepared_key(struct super_block *sb, + struct fscrypt_prepared_key *prep_key); + +int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key); + +int fscrypt_derive_dirhash_key(struct fscrypt_info *ci, + const struct fscrypt_master_key *mk); -extern int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, - const u8 *raw_key); +void fscrypt_hash_inode_number(struct fscrypt_info *ci, + const struct fscrypt_master_key *mk); -extern int fscrypt_derive_dirhash_key(struct fscrypt_info *ci, - const struct fscrypt_master_key *mk); +int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported); + +/** + * fscrypt_require_key() - require an inode's encryption key + * @inode: the inode we need the key for + * + * If the inode is encrypted, set up its encryption key if not already done. + * Then require that the key be present and return -ENOKEY otherwise. + * + * No locks are needed, and the key will live as long as the struct inode --- so + * it won't go away from under you. + * + * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code + * if a problem occurred while setting up the encryption key. + */ +static inline int fscrypt_require_key(struct inode *inode) +{ + if (IS_ENCRYPTED(inode)) { + int err = fscrypt_get_encryption_info(inode, false); + + if (err) + return err; + if (!fscrypt_has_encryption_key(inode)) + return -ENOKEY; + } + return 0; +} /* keysetup_v1.c */ -extern void fscrypt_put_direct_key(struct fscrypt_direct_key *dk); +void fscrypt_put_direct_key(struct fscrypt_direct_key *dk); + +int fscrypt_setup_v1_file_key(struct fscrypt_info *ci, + const u8 *raw_master_key); -extern int fscrypt_setup_v1_file_key(struct fscrypt_info *ci, - const u8 *raw_master_key); +int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci); -extern int fscrypt_setup_v1_file_key_via_subscribed_keyrings( - struct fscrypt_info *ci); /* policy.c */ -extern bool fscrypt_policies_equal(const union fscrypt_policy *policy1, - const union fscrypt_policy *policy2); -extern bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, - const struct inode *inode); -extern int fscrypt_policy_from_context(union fscrypt_policy *policy_u, - const union fscrypt_context *ctx_u, - int ctx_size); +bool fscrypt_policies_equal(const union fscrypt_policy *policy1, + const union fscrypt_policy *policy2); +int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy, + struct fscrypt_key_specifier *key_spec); +bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, + const struct inode *inode); +int fscrypt_policy_from_context(union fscrypt_policy *policy_u, + const union fscrypt_context *ctx_u, + int ctx_size); +const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir); #endif /* _FSCRYPT_PRIVATE_H */ diff --git a/fs/crypto/hkdf.c b/fs/crypto/hkdf.c index efb95bd19a89..7607d18b35fc 100644 --- a/fs/crypto/hkdf.c +++ b/fs/crypto/hkdf.c @@ -10,15 +10,20 @@ */ #include <crypto/hash.h> -#include <crypto/sha.h> +#include <crypto/sha2.h> #include "fscrypt_private.h" /* * HKDF supports any unkeyed cryptographic hash algorithm, but fscrypt uses - * SHA-512 because it is reasonably secure and efficient; and since it produces - * a 64-byte digest, deriving an AES-256-XTS key preserves all 64 bytes of - * entropy from the master key and requires only one iteration of HKDF-Expand. + * SHA-512 because it is well-established, secure, and reasonably efficient. + * + * HKDF-SHA256 was also considered, as its 256-bit security strength would be + * sufficient here. A 512-bit security strength is "nice to have", though. + * Also, on 64-bit CPUs, SHA-512 is usually just as fast as SHA-256. In the + * common case of deriving an AES-256-XTS key (512 bits), that can result in + * HKDF-SHA512 being much faster than HKDF-SHA256, as the longer digest size of + * SHA-512 causes HKDF-Expand to only need to do one iteration rather than two. */ #define HKDF_HMAC_ALG "hmac(sha512)" #define HKDF_HASHLEN SHA512_DIGEST_SIZE @@ -44,17 +49,13 @@ static int hkdf_extract(struct crypto_shash *hmac_tfm, const u8 *ikm, unsigned int ikmlen, u8 prk[HKDF_HASHLEN]) { static const u8 default_salt[HKDF_HASHLEN]; - SHASH_DESC_ON_STACK(desc, hmac_tfm); int err; err = crypto_shash_setkey(hmac_tfm, default_salt, HKDF_HASHLEN); if (err) return err; - desc->tfm = hmac_tfm; - err = crypto_shash_digest(desc, ikm, ikmlen, prk); - shash_desc_zero(desc); - return err; + return crypto_shash_tfm_digest(hmac_tfm, ikm, ikmlen, prk); } /* diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 5ef861742921..7b8c5a1104b5 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -5,12 +5,10 @@ * Encryption hooks for higher-level filesystem operations. */ -#include <linux/key.h> - #include "fscrypt_private.h" /** - * fscrypt_file_open - prepare to open a possibly-encrypted regular file + * fscrypt_file_open() - prepare to open a possibly-encrypted regular file * @inode: the inode being opened * @filp: the struct file being set up * @@ -54,15 +52,12 @@ EXPORT_SYMBOL_GPL(fscrypt_file_open); int __fscrypt_prepare_link(struct inode *inode, struct inode *dir, struct dentry *dentry) { - int err; - - err = fscrypt_require_key(dir); - if (err) - return err; - - /* ... in case we looked up ciphertext name before key was added */ - if (dentry->d_flags & DCACHE_ENCRYPTED_NAME) + if (fscrypt_is_nokey_name(dentry)) return -ENOKEY; + /* + * We don't need to separately check that the directory inode's key is + * available, as it's implied by the dentry not being a no-key name. + */ if (!fscrypt_has_permitted_context(dir, inode)) return -EXDEV; @@ -75,20 +70,13 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags) { - int err; - - err = fscrypt_require_key(old_dir); - if (err) - return err; - - err = fscrypt_require_key(new_dir); - if (err) - return err; - - /* ... in case we looked up ciphertext name(s) before key was added */ - if ((old_dentry->d_flags | new_dentry->d_flags) & - DCACHE_ENCRYPTED_NAME) + if (fscrypt_is_nokey_name(old_dentry) || + fscrypt_is_nokey_name(new_dentry)) return -ENOKEY; + /* + * We don't need to separately check that the directory inodes' keys are + * available, as it's implied by the dentries not being no-key names. + */ if (old_dir != new_dir) { if (IS_ENCRYPTED(new_dir) && @@ -114,16 +102,29 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, if (err && err != -ENOENT) return err; - if (fname->is_ciphertext_name) { + if (fname->is_nokey_name) { spin_lock(&dentry->d_lock); - dentry->d_flags |= DCACHE_ENCRYPTED_NAME; + dentry->d_flags |= DCACHE_NOKEY_NAME; spin_unlock(&dentry->d_lock); - d_set_d_op(dentry, &fscrypt_d_ops); } return err; } EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup); +int __fscrypt_prepare_readdir(struct inode *dir) +{ + return fscrypt_get_encryption_info(dir, true); +} +EXPORT_SYMBOL_GPL(__fscrypt_prepare_readdir); + +int __fscrypt_prepare_setattr(struct dentry *dentry, struct iattr *attr) +{ + if (attr->ia_valid & ATTR_SIZE) + return fscrypt_require_key(d_inode(dentry)); + return 0; +} +EXPORT_SYMBOL_GPL(__fscrypt_prepare_setattr); + /** * fscrypt_prepare_setflags() - prepare to change flags with FS_IOC_SETFLAGS * @inode: the inode on which flags are being changed @@ -154,38 +155,63 @@ int fscrypt_prepare_setflags(struct inode *inode, ci = inode->i_crypt_info; if (ci->ci_policy.version != FSCRYPT_POLICY_V2) return -EINVAL; - mk = ci->ci_master_key->payload.data[0]; - down_read(&mk->mk_secret_sem); + mk = ci->ci_master_key; + down_read(&mk->mk_sem); if (is_master_key_secret_present(&mk->mk_secret)) err = fscrypt_derive_dirhash_key(ci, mk); else err = -ENOKEY; - up_read(&mk->mk_secret_sem); + up_read(&mk->mk_sem); return err; } return 0; } -int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, - unsigned int max_len, - struct fscrypt_str *disk_link) +/** + * fscrypt_prepare_symlink() - prepare to create a possibly-encrypted symlink + * @dir: directory in which the symlink is being created + * @target: plaintext symlink target + * @len: length of @target excluding null terminator + * @max_len: space the filesystem has available to store the symlink target + * @disk_link: (out) the on-disk symlink target being prepared + * + * This function computes the size the symlink target will require on-disk, + * stores it in @disk_link->len, and validates it against @max_len. An + * encrypted symlink may be longer than the original. + * + * Additionally, @disk_link->name is set to @target if the symlink will be + * unencrypted, but left NULL if the symlink will be encrypted. For encrypted + * symlinks, the filesystem must call fscrypt_encrypt_symlink() to create the + * on-disk target later. (The reason for the two-step process is that some + * filesystems need to know the size of the symlink target before creating the + * inode, e.g. to determine whether it will be a "fast" or "slow" symlink.) + * + * Return: 0 on success, -ENAMETOOLONG if the symlink target is too long, + * -ENOKEY if the encryption key is missing, or another -errno code if a problem + * occurred while setting up the encryption key. + */ +int fscrypt_prepare_symlink(struct inode *dir, const char *target, + unsigned int len, unsigned int max_len, + struct fscrypt_str *disk_link) { - int err; + const union fscrypt_policy *policy; /* * To calculate the size of the encrypted symlink target we need to know * the amount of NUL padding, which is determined by the flags set in * the encryption policy which will be inherited from the directory. - * The easiest way to get access to this is to just load the directory's - * fscrypt_info, since we'll need it to create the dir_entry anyway. - * - * Note: in test_dummy_encryption mode, @dir may be unencrypted. */ - err = fscrypt_get_encryption_info(dir); - if (err) - return err; - if (!fscrypt_has_encryption_key(dir)) - return -ENOKEY; + policy = fscrypt_policy_to_inherit(dir); + if (policy == NULL) { + /* Not encrypted */ + disk_link->name = (unsigned char *)target; + disk_link->len = len + 1; + if (disk_link->len > max_len) + return -ENAMETOOLONG; + return 0; + } + if (IS_ERR(policy)) + return PTR_ERR(policy); /* * Calculate the size of the encrypted symlink and verify it won't @@ -198,16 +224,16 @@ int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, * counting it (even though it is meaningless for ciphertext) is simpler * for now since filesystems will assume it is there and subtract it. */ - if (!fscrypt_fname_encrypted_size(dir, len, - max_len - sizeof(struct fscrypt_symlink_data), - &disk_link->len)) + if (!__fscrypt_fname_encrypted_size(policy, len, + max_len - sizeof(struct fscrypt_symlink_data), + &disk_link->len)) return -ENAMETOOLONG; disk_link->len += sizeof(struct fscrypt_symlink_data); disk_link->name = NULL; return 0; } -EXPORT_SYMBOL_GPL(__fscrypt_prepare_symlink); +EXPORT_SYMBOL_GPL(fscrypt_prepare_symlink); int __fscrypt_encrypt_symlink(struct inode *inode, const char *target, unsigned int len, struct fscrypt_str *disk_link) @@ -217,9 +243,13 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target, struct fscrypt_symlink_data *sd; unsigned int ciphertext_len; - err = fscrypt_require_key(inode); - if (err) - return err; + /* + * fscrypt_prepare_new_inode() should have already set up the new + * symlink inode's encryption key. We don't wait until now to do it, + * since we may be in a filesystem transaction now. + */ + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(inode))) + return -ENOKEY; if (disk_link->name) { /* filesystem-provided buffer */ @@ -262,7 +292,7 @@ err_free_sd: EXPORT_SYMBOL_GPL(__fscrypt_encrypt_symlink); /** - * fscrypt_get_symlink - get the target of an encrypted symlink + * fscrypt_get_symlink() - get the target of an encrypted symlink * @inode: the symlink inode * @caddr: the on-disk contents of the symlink * @max_size: size of @caddr buffer @@ -297,7 +327,7 @@ const char *fscrypt_get_symlink(struct inode *inode, const void *caddr, * Try to set up the symlink's encryption key, but we can continue * regardless of whether the key is available or not. */ - err = fscrypt_get_encryption_info(inode); + err = fscrypt_get_encryption_info(inode, false); if (err) return ERR_PTR(err); has_key = fscrypt_has_encryption_key(inode); @@ -319,7 +349,7 @@ const char *fscrypt_get_symlink(struct inode *inode, const void *caddr, if (cstr.len + sizeof(*sd) - 1 > max_size) return ERR_PTR(-EUCLEAN); - err = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr); + err = fscrypt_fname_alloc_buffer(cstr.len, &pstr); if (err) return ERR_PTR(err); @@ -350,3 +380,47 @@ err_kfree: return ERR_PTR(err); } EXPORT_SYMBOL_GPL(fscrypt_get_symlink); + +/** + * fscrypt_symlink_getattr() - set the correct st_size for encrypted symlinks + * @path: the path for the encrypted symlink being queried + * @stat: the struct being filled with the symlink's attributes + * + * Override st_size of encrypted symlinks to be the length of the decrypted + * symlink target (or the no-key encoded symlink target, if the key is + * unavailable) rather than the length of the encrypted symlink target. This is + * necessary for st_size to match the symlink target that userspace actually + * sees. POSIX requires this, and some userspace programs depend on it. + * + * This requires reading the symlink target from disk if needed, setting up the + * inode's encryption key if possible, and then decrypting or encoding the + * symlink target. This makes lstat() more heavyweight than is normally the + * case. However, decrypted symlink targets will be cached in ->i_link, so + * usually the symlink won't have to be read and decrypted again later if/when + * it is actually followed, readlink() is called, or lstat() is called again. + * + * Return: 0 on success, -errno on failure + */ +int fscrypt_symlink_getattr(const struct path *path, struct kstat *stat) +{ + struct dentry *dentry = path->dentry; + struct inode *inode = d_inode(dentry); + const char *link; + DEFINE_DELAYED_CALL(done); + + /* + * To get the symlink target that userspace will see (whether it's the + * decrypted target or the no-key encoded target), we can just get it in + * the same way the VFS does during path resolution and readlink(). + */ + link = READ_ONCE(inode->i_link); + if (!link) { + link = inode->i_op->get_link(dentry, inode, &done); + if (IS_ERR(link)) + return PTR_ERR(link); + } + stat->size = strlen(link); + do_delayed_call(&done); + return 0; +} +EXPORT_SYMBOL_GPL(fscrypt_symlink_getattr); diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c new file mode 100644 index 000000000000..cea8b14007e6 --- /dev/null +++ b/fs/crypto/inline_crypt.c @@ -0,0 +1,483 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Inline encryption support for fscrypt + * + * Copyright 2019 Google LLC + */ + +/* + * With "inline encryption", the block layer handles the decryption/encryption + * as part of the bio, instead of the filesystem doing the crypto itself via + * crypto API. See Documentation/block/inline-encryption.rst. fscrypt still + * provides the key and IV to use. + */ + +#include <linux/blk-crypto-profile.h> +#include <linux/blkdev.h> +#include <linux/buffer_head.h> +#include <linux/sched/mm.h> +#include <linux/slab.h> +#include <linux/uio.h> + +#include "fscrypt_private.h" + +static struct block_device **fscrypt_get_devices(struct super_block *sb, + unsigned int *num_devs) +{ + struct block_device **devs; + + if (sb->s_cop->get_devices) { + devs = sb->s_cop->get_devices(sb, num_devs); + if (devs) + return devs; + } + devs = kmalloc(sizeof(*devs), GFP_KERNEL); + if (!devs) + return ERR_PTR(-ENOMEM); + devs[0] = sb->s_bdev; + *num_devs = 1; + return devs; +} + +static unsigned int fscrypt_get_dun_bytes(const struct fscrypt_info *ci) +{ + struct super_block *sb = ci->ci_inode->i_sb; + unsigned int flags = fscrypt_policy_flags(&ci->ci_policy); + int ino_bits = 64, lblk_bits = 64; + + if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) + return offsetofend(union fscrypt_iv, nonce); + + if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) + return sizeof(__le64); + + if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) + return sizeof(__le32); + + /* Default case: IVs are just the file logical block number */ + if (sb->s_cop->get_ino_and_lblk_bits) + sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits); + return DIV_ROUND_UP(lblk_bits, 8); +} + +/* + * Log a message when starting to use blk-crypto (native) or blk-crypto-fallback + * for an encryption mode for the first time. This is the blk-crypto + * counterpart to the message logged when starting to use the crypto API for the + * first time. A limitation is that these messages don't convey which specific + * filesystems or files are using each implementation. However, *usually* + * systems use just one implementation per mode, which makes these messages + * helpful for debugging problems where the "wrong" implementation is used. + */ +static void fscrypt_log_blk_crypto_impl(struct fscrypt_mode *mode, + struct block_device **devs, + unsigned int num_devs, + const struct blk_crypto_config *cfg) +{ + unsigned int i; + + for (i = 0; i < num_devs; i++) { + struct request_queue *q = bdev_get_queue(devs[i]); + + if (!IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) || + __blk_crypto_cfg_supported(q->crypto_profile, cfg)) { + if (!xchg(&mode->logged_blk_crypto_native, 1)) + pr_info("fscrypt: %s using blk-crypto (native)\n", + mode->friendly_name); + } else if (!xchg(&mode->logged_blk_crypto_fallback, 1)) { + pr_info("fscrypt: %s using blk-crypto-fallback\n", + mode->friendly_name); + } + } +} + +/* Enable inline encryption for this file if supported. */ +int fscrypt_select_encryption_impl(struct fscrypt_info *ci) +{ + const struct inode *inode = ci->ci_inode; + struct super_block *sb = inode->i_sb; + struct blk_crypto_config crypto_cfg; + struct block_device **devs; + unsigned int num_devs; + unsigned int i; + + /* The file must need contents encryption, not filenames encryption */ + if (!S_ISREG(inode->i_mode)) + return 0; + + /* The crypto mode must have a blk-crypto counterpart */ + if (ci->ci_mode->blk_crypto_mode == BLK_ENCRYPTION_MODE_INVALID) + return 0; + + /* The filesystem must be mounted with -o inlinecrypt */ + if (!(sb->s_flags & SB_INLINECRYPT)) + return 0; + + /* + * When a page contains multiple logically contiguous filesystem blocks, + * some filesystem code only calls fscrypt_mergeable_bio() for the first + * block in the page. This is fine for most of fscrypt's IV generation + * strategies, where contiguous blocks imply contiguous IVs. But it + * doesn't work with IV_INO_LBLK_32. For now, simply exclude + * IV_INO_LBLK_32 with blocksize != PAGE_SIZE from inline encryption. + */ + if ((fscrypt_policy_flags(&ci->ci_policy) & + FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && + sb->s_blocksize != PAGE_SIZE) + return 0; + + /* + * On all the filesystem's block devices, blk-crypto must support the + * crypto configuration that the file would use. + */ + crypto_cfg.crypto_mode = ci->ci_mode->blk_crypto_mode; + crypto_cfg.data_unit_size = sb->s_blocksize; + crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci); + + devs = fscrypt_get_devices(sb, &num_devs); + if (IS_ERR(devs)) + return PTR_ERR(devs); + + for (i = 0; i < num_devs; i++) { + if (!blk_crypto_config_supported(bdev_get_queue(devs[i]), + &crypto_cfg)) + goto out_free_devs; + } + + fscrypt_log_blk_crypto_impl(ci->ci_mode, devs, num_devs, &crypto_cfg); + + ci->ci_inlinecrypt = true; +out_free_devs: + kfree(devs); + + return 0; +} + +int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, + const u8 *raw_key, + const struct fscrypt_info *ci) +{ + const struct inode *inode = ci->ci_inode; + struct super_block *sb = inode->i_sb; + enum blk_crypto_mode_num crypto_mode = ci->ci_mode->blk_crypto_mode; + struct blk_crypto_key *blk_key; + struct block_device **devs; + unsigned int num_devs; + unsigned int i; + int err; + + blk_key = kmalloc(sizeof(*blk_key), GFP_KERNEL); + if (!blk_key) + return -ENOMEM; + + err = blk_crypto_init_key(blk_key, raw_key, crypto_mode, + fscrypt_get_dun_bytes(ci), sb->s_blocksize); + if (err) { + fscrypt_err(inode, "error %d initializing blk-crypto key", err); + goto fail; + } + + /* Start using blk-crypto on all the filesystem's block devices. */ + devs = fscrypt_get_devices(sb, &num_devs); + if (IS_ERR(devs)) { + err = PTR_ERR(devs); + goto fail; + } + for (i = 0; i < num_devs; i++) { + err = blk_crypto_start_using_key(blk_key, + bdev_get_queue(devs[i])); + if (err) + break; + } + kfree(devs); + if (err) { + fscrypt_err(inode, "error %d starting to use blk-crypto", err); + goto fail; + } + + /* + * Pairs with the smp_load_acquire() in fscrypt_is_key_prepared(). + * I.e., here we publish ->blk_key with a RELEASE barrier so that + * concurrent tasks can ACQUIRE it. Note that this concurrency is only + * possible for per-mode keys, not for per-file keys. + */ + smp_store_release(&prep_key->blk_key, blk_key); + return 0; + +fail: + kfree_sensitive(blk_key); + return err; +} + +void fscrypt_destroy_inline_crypt_key(struct super_block *sb, + struct fscrypt_prepared_key *prep_key) +{ + struct blk_crypto_key *blk_key = prep_key->blk_key; + struct block_device **devs; + unsigned int num_devs; + unsigned int i; + + if (!blk_key) + return; + + /* Evict the key from all the filesystem's block devices. */ + devs = fscrypt_get_devices(sb, &num_devs); + if (!IS_ERR(devs)) { + for (i = 0; i < num_devs; i++) + blk_crypto_evict_key(bdev_get_queue(devs[i]), blk_key); + kfree(devs); + } + kfree_sensitive(blk_key); +} + +bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode) +{ + return inode->i_crypt_info->ci_inlinecrypt; +} +EXPORT_SYMBOL_GPL(__fscrypt_inode_uses_inline_crypto); + +static void fscrypt_generate_dun(const struct fscrypt_info *ci, u64 lblk_num, + u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]) +{ + union fscrypt_iv iv; + int i; + + fscrypt_generate_iv(&iv, lblk_num, ci); + + BUILD_BUG_ON(FSCRYPT_MAX_IV_SIZE > BLK_CRYPTO_MAX_IV_SIZE); + memset(dun, 0, BLK_CRYPTO_MAX_IV_SIZE); + for (i = 0; i < ci->ci_mode->ivsize/sizeof(dun[0]); i++) + dun[i] = le64_to_cpu(iv.dun[i]); +} + +/** + * fscrypt_set_bio_crypt_ctx() - prepare a file contents bio for inline crypto + * @bio: a bio which will eventually be submitted to the file + * @inode: the file's inode + * @first_lblk: the first file logical block number in the I/O + * @gfp_mask: memory allocation flags - these must be a waiting mask so that + * bio_crypt_set_ctx can't fail. + * + * If the contents of the file should be encrypted (or decrypted) with inline + * encryption, then assign the appropriate encryption context to the bio. + * + * Normally the bio should be newly allocated (i.e. no pages added yet), as + * otherwise fscrypt_mergeable_bio() won't work as intended. + * + * The encryption context will be freed automatically when the bio is freed. + */ +void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode, + u64 first_lblk, gfp_t gfp_mask) +{ + const struct fscrypt_info *ci; + u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; + + if (!fscrypt_inode_uses_inline_crypto(inode)) + return; + ci = inode->i_crypt_info; + + fscrypt_generate_dun(ci, first_lblk, dun); + bio_crypt_set_ctx(bio, ci->ci_enc_key.blk_key, dun, gfp_mask); +} +EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx); + +/* Extract the inode and logical block number from a buffer_head. */ +static bool bh_get_inode_and_lblk_num(const struct buffer_head *bh, + const struct inode **inode_ret, + u64 *lblk_num_ret) +{ + struct page *page = bh->b_page; + const struct address_space *mapping; + const struct inode *inode; + + /* + * The ext4 journal (jbd2) can submit a buffer_head it directly created + * for a non-pagecache page. fscrypt doesn't care about these. + */ + mapping = page_mapping(page); + if (!mapping) + return false; + inode = mapping->host; + + *inode_ret = inode; + *lblk_num_ret = ((u64)page->index << (PAGE_SHIFT - inode->i_blkbits)) + + (bh_offset(bh) >> inode->i_blkbits); + return true; +} + +/** + * fscrypt_set_bio_crypt_ctx_bh() - prepare a file contents bio for inline + * crypto + * @bio: a bio which will eventually be submitted to the file + * @first_bh: the first buffer_head for which I/O will be submitted + * @gfp_mask: memory allocation flags + * + * Same as fscrypt_set_bio_crypt_ctx(), except this takes a buffer_head instead + * of an inode and block number directly. + */ +void fscrypt_set_bio_crypt_ctx_bh(struct bio *bio, + const struct buffer_head *first_bh, + gfp_t gfp_mask) +{ + const struct inode *inode; + u64 first_lblk; + + if (bh_get_inode_and_lblk_num(first_bh, &inode, &first_lblk)) + fscrypt_set_bio_crypt_ctx(bio, inode, first_lblk, gfp_mask); +} +EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx_bh); + +/** + * fscrypt_mergeable_bio() - test whether data can be added to a bio + * @bio: the bio being built up + * @inode: the inode for the next part of the I/O + * @next_lblk: the next file logical block number in the I/O + * + * When building a bio which may contain data which should undergo inline + * encryption (or decryption) via fscrypt, filesystems should call this function + * to ensure that the resulting bio contains only contiguous data unit numbers. + * This will return false if the next part of the I/O cannot be merged with the + * bio because either the encryption key would be different or the encryption + * data unit numbers would be discontiguous. + * + * fscrypt_set_bio_crypt_ctx() must have already been called on the bio. + * + * This function isn't required in cases where crypto-mergeability is ensured in + * another way, such as I/O targeting only a single file (and thus a single key) + * combined with fscrypt_limit_io_blocks() to ensure DUN contiguity. + * + * Return: true iff the I/O is mergeable + */ +bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode, + u64 next_lblk) +{ + const struct bio_crypt_ctx *bc = bio->bi_crypt_context; + u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; + + if (!!bc != fscrypt_inode_uses_inline_crypto(inode)) + return false; + if (!bc) + return true; + + /* + * Comparing the key pointers is good enough, as all I/O for each key + * uses the same pointer. I.e., there's currently no need to support + * merging requests where the keys are the same but the pointers differ. + */ + if (bc->bc_key != inode->i_crypt_info->ci_enc_key.blk_key) + return false; + + fscrypt_generate_dun(inode->i_crypt_info, next_lblk, next_dun); + return bio_crypt_dun_is_contiguous(bc, bio->bi_iter.bi_size, next_dun); +} +EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio); + +/** + * fscrypt_mergeable_bio_bh() - test whether data can be added to a bio + * @bio: the bio being built up + * @next_bh: the next buffer_head for which I/O will be submitted + * + * Same as fscrypt_mergeable_bio(), except this takes a buffer_head instead of + * an inode and block number directly. + * + * Return: true iff the I/O is mergeable + */ +bool fscrypt_mergeable_bio_bh(struct bio *bio, + const struct buffer_head *next_bh) +{ + const struct inode *inode; + u64 next_lblk; + + if (!bh_get_inode_and_lblk_num(next_bh, &inode, &next_lblk)) + return !bio->bi_crypt_context; + + return fscrypt_mergeable_bio(bio, inode, next_lblk); +} +EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh); + +/** + * fscrypt_dio_supported() - check whether DIO (direct I/O) is supported on an + * inode, as far as encryption is concerned + * @inode: the inode in question + * + * Return: %true if there are no encryption constraints that prevent DIO from + * being supported; %false if DIO is unsupported. (Note that in the + * %true case, the filesystem might have other, non-encryption-related + * constraints that prevent DIO from actually being supported. Also, on + * encrypted files the filesystem is still responsible for only allowing + * DIO when requests are filesystem-block-aligned.) + */ +bool fscrypt_dio_supported(struct inode *inode) +{ + int err; + + /* If the file is unencrypted, no veto from us. */ + if (!fscrypt_needs_contents_encryption(inode)) + return true; + + /* + * We only support DIO with inline crypto, not fs-layer crypto. + * + * To determine whether the inode is using inline crypto, we have to set + * up the key if it wasn't already done. This is because in the current + * design of fscrypt, the decision of whether to use inline crypto or + * not isn't made until the inode's encryption key is being set up. In + * the DIO read/write case, the key will always be set up already, since + * the file will be open. But in the case of statx(), the key might not + * be set up yet, as the file might not have been opened yet. + */ + err = fscrypt_require_key(inode); + if (err) { + /* + * Key unavailable or couldn't be set up. This edge case isn't + * worth worrying about; just report that DIO is unsupported. + */ + return false; + } + return fscrypt_inode_uses_inline_crypto(inode); +} +EXPORT_SYMBOL_GPL(fscrypt_dio_supported); + +/** + * fscrypt_limit_io_blocks() - limit I/O blocks to avoid discontiguous DUNs + * @inode: the file on which I/O is being done + * @lblk: the block at which the I/O is being started from + * @nr_blocks: the number of blocks we want to submit starting at @lblk + * + * Determine the limit to the number of blocks that can be submitted in a bio + * targeting @lblk without causing a data unit number (DUN) discontiguity. + * + * This is normally just @nr_blocks, as normally the DUNs just increment along + * with the logical blocks. (Or the file is not encrypted.) + * + * In rare cases, fscrypt can be using an IV generation method that allows the + * DUN to wrap around within logically contiguous blocks, and that wraparound + * will occur. If this happens, a value less than @nr_blocks will be returned + * so that the wraparound doesn't occur in the middle of a bio, which would + * cause encryption/decryption to produce wrong results. + * + * Return: the actual number of blocks that can be submitted + */ +u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks) +{ + const struct fscrypt_info *ci; + u32 dun; + + if (!fscrypt_inode_uses_inline_crypto(inode)) + return nr_blocks; + + if (nr_blocks <= 1) + return nr_blocks; + + ci = inode->i_crypt_info; + if (!(fscrypt_policy_flags(&ci->ci_policy) & + FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) + return nr_blocks; + + /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */ + + dun = ci->ci_hashed_ino + lblk; + + return min_t(u64, nr_blocks, (u64)U32_MAX + 1 - dun); +} +EXPORT_SYMBOL_GPL(fscrypt_limit_io_blocks); diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index ab41b25d4fa1..2a24b1f0ae68 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -18,12 +18,26 @@ * information about these ioctls. */ +#include <asm/unaligned.h> #include <crypto/skcipher.h> #include <linux/key-type.h> +#include <linux/random.h> #include <linux/seq_file.h> #include "fscrypt_private.h" +/* The master encryption keys for a filesystem (->s_master_keys) */ +struct fscrypt_keyring { + /* + * Lock that protects ->key_hashtable. It does *not* protect the + * fscrypt_master_key structs themselves. + */ + spinlock_t lock; + + /* Hash table that maps fscrypt_key_specifier to fscrypt_master_key */ + struct hlist_head key_hashtable[128]; +}; + static void wipe_master_key_secret(struct fscrypt_master_key_secret *secret) { fscrypt_destroy_hkdf(&secret->hkdf); @@ -37,19 +51,73 @@ static void move_master_key_secret(struct fscrypt_master_key_secret *dst, memzero_explicit(src, sizeof(*src)); } -static void free_master_key(struct fscrypt_master_key *mk) +static void fscrypt_free_master_key(struct rcu_head *head) +{ + struct fscrypt_master_key *mk = + container_of(head, struct fscrypt_master_key, mk_rcu_head); + /* + * The master key secret and any embedded subkeys should have already + * been wiped when the last active reference to the fscrypt_master_key + * struct was dropped; doing it here would be unnecessarily late. + * Nevertheless, use kfree_sensitive() in case anything was missed. + */ + kfree_sensitive(mk); +} + +void fscrypt_put_master_key(struct fscrypt_master_key *mk) +{ + if (!refcount_dec_and_test(&mk->mk_struct_refs)) + return; + /* + * No structural references left, so free ->mk_users, and also free the + * fscrypt_master_key struct itself after an RCU grace period ensures + * that concurrent keyring lookups can no longer find it. + */ + WARN_ON(refcount_read(&mk->mk_active_refs) != 0); + key_put(mk->mk_users); + mk->mk_users = NULL; + call_rcu(&mk->mk_rcu_head, fscrypt_free_master_key); +} + +void fscrypt_put_master_key_activeref(struct fscrypt_master_key *mk) { + struct super_block *sb = mk->mk_sb; + struct fscrypt_keyring *keyring = sb->s_master_keys; size_t i; - wipe_master_key_secret(&mk->mk_secret); + if (!refcount_dec_and_test(&mk->mk_active_refs)) + return; + /* + * No active references left, so complete the full removal of this + * fscrypt_master_key struct by removing it from the keyring and + * destroying any subkeys embedded in it. + */ - for (i = 0; i <= __FSCRYPT_MODE_MAX; i++) { - crypto_free_skcipher(mk->mk_direct_tfms[i]); - crypto_free_skcipher(mk->mk_iv_ino_lblk_64_tfms[i]); + spin_lock(&keyring->lock); + hlist_del_rcu(&mk->mk_node); + spin_unlock(&keyring->lock); + + /* + * ->mk_active_refs == 0 implies that ->mk_secret is not present and + * that ->mk_decrypted_inodes is empty. + */ + WARN_ON(is_master_key_secret_present(&mk->mk_secret)); + WARN_ON(!list_empty(&mk->mk_decrypted_inodes)); + + for (i = 0; i <= FSCRYPT_MODE_MAX; i++) { + fscrypt_destroy_prepared_key( + sb, &mk->mk_direct_keys[i]); + fscrypt_destroy_prepared_key( + sb, &mk->mk_iv_ino_lblk_64_keys[i]); + fscrypt_destroy_prepared_key( + sb, &mk->mk_iv_ino_lblk_32_keys[i]); } + memzero_explicit(&mk->mk_ino_hash_key, + sizeof(mk->mk_ino_hash_key)); + mk->mk_ino_hash_key_initialized = false; - key_put(mk->mk_users); - kzfree(mk); + /* Drop the structural ref associated with the active refs. */ + fscrypt_put_master_key(mk); } static inline bool valid_key_spec(const struct fscrypt_key_specifier *spec) @@ -59,44 +127,6 @@ static inline bool valid_key_spec(const struct fscrypt_key_specifier *spec) return master_key_spec_len(spec) != 0; } -static int fscrypt_key_instantiate(struct key *key, - struct key_preparsed_payload *prep) -{ - key->payload.data[0] = (struct fscrypt_master_key *)prep->data; - return 0; -} - -static void fscrypt_key_destroy(struct key *key) -{ - free_master_key(key->payload.data[0]); -} - -static void fscrypt_key_describe(const struct key *key, struct seq_file *m) -{ - seq_puts(m, key->description); - - if (key_is_positive(key)) { - const struct fscrypt_master_key *mk = key->payload.data[0]; - - if (!is_master_key_secret_present(&mk->mk_secret)) - seq_puts(m, ": secret removed"); - } -} - -/* - * Type of key in ->s_master_keys. Each key of this type represents a master - * key which has been added to the filesystem. Its payload is a - * 'struct fscrypt_master_key'. The "." prefix in the key type name prevents - * users from adding keys of this type via the keyrings syscalls rather than via - * the intended method of FS_IOC_ADD_ENCRYPTION_KEY. - */ -static struct key_type key_type_fscrypt = { - .name = "._fscrypt", - .instantiate = fscrypt_key_instantiate, - .destroy = fscrypt_key_destroy, - .describe = fscrypt_key_describe, -}; - static int fscrypt_user_key_instantiate(struct key *key, struct key_preparsed_payload *prep) { @@ -129,32 +159,6 @@ static struct key_type key_type_fscrypt_user = { .describe = fscrypt_user_key_describe, }; -/* Search ->s_master_keys or ->mk_users */ -static struct key *search_fscrypt_keyring(struct key *keyring, - struct key_type *type, - const char *description) -{ - /* - * We need to mark the keyring reference as "possessed" so that we - * acquire permission to search it, via the KEY_POS_SEARCH permission. - */ - key_ref_t keyref = make_key_ref(keyring, true /* possessed */); - - keyref = keyring_search(keyref, type, description, false); - if (IS_ERR(keyref)) { - if (PTR_ERR(keyref) == -EAGAIN || /* not found */ - PTR_ERR(keyref) == -EKEYREVOKED) /* recently invalidated */ - keyref = ERR_PTR(-ENOKEY); - return ERR_CAST(keyref); - } - return key_ref_to_ptr(keyref); -} - -#define FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE \ - (CONST_STRLEN("fscrypt-") + sizeof_field(struct super_block, s_id)) - -#define FSCRYPT_MK_DESCRIPTION_SIZE (2 * FSCRYPT_KEY_IDENTIFIER_SIZE + 1) - #define FSCRYPT_MK_USERS_DESCRIPTION_SIZE \ (CONST_STRLEN("fscrypt-") + 2 * FSCRYPT_KEY_IDENTIFIER_SIZE + \ CONST_STRLEN("-users") + 1) @@ -162,21 +166,6 @@ static struct key *search_fscrypt_keyring(struct key *keyring, #define FSCRYPT_MK_USER_DESCRIPTION_SIZE \ (2 * FSCRYPT_KEY_IDENTIFIER_SIZE + CONST_STRLEN(".uid.") + 10 + 1) -static void format_fs_keyring_description( - char description[FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE], - const struct super_block *sb) -{ - sprintf(description, "fscrypt-%s", sb->s_id); -} - -static void format_mk_description( - char description[FSCRYPT_MK_DESCRIPTION_SIZE], - const struct fscrypt_key_specifier *mk_spec) -{ - sprintf(description, "%*phN", - master_key_spec_len(mk_spec), (u8 *)&mk_spec->u); -} - static void format_mk_users_keyring_description( char description[FSCRYPT_MK_USERS_DESCRIPTION_SIZE], const u8 mk_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]) @@ -197,48 +186,139 @@ static void format_mk_user_description( /* Create ->s_master_keys if needed. Synchronized by fscrypt_add_key_mutex. */ static int allocate_filesystem_keyring(struct super_block *sb) { - char description[FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE]; - struct key *keyring; + struct fscrypt_keyring *keyring; if (sb->s_master_keys) return 0; - format_fs_keyring_description(description, sb); - keyring = keyring_alloc(description, GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, - current_cred(), KEY_POS_SEARCH | - KEY_USR_SEARCH | KEY_USR_READ | KEY_USR_VIEW, - KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL); - if (IS_ERR(keyring)) - return PTR_ERR(keyring); - - /* Pairs with READ_ONCE() in fscrypt_find_master_key() */ + keyring = kzalloc(sizeof(*keyring), GFP_KERNEL); + if (!keyring) + return -ENOMEM; + spin_lock_init(&keyring->lock); + /* + * Pairs with the smp_load_acquire() in fscrypt_find_master_key(). + * I.e., here we publish ->s_master_keys with a RELEASE barrier so that + * concurrent tasks can ACQUIRE it. + */ smp_store_release(&sb->s_master_keys, keyring); return 0; } -void fscrypt_sb_free(struct super_block *sb) +/* + * Release all encryption keys that have been added to the filesystem, along + * with the keyring that contains them. + * + * This is called at unmount time. The filesystem's underlying block device(s) + * are still available at this time; this is important because after user file + * accesses have been allowed, this function may need to evict keys from the + * keyslots of an inline crypto engine, which requires the block device(s). + * + * This is also called when the super_block is being freed. This is needed to + * avoid a memory leak if mounting fails after the "test_dummy_encryption" + * option was processed, as in that case the unmount-time call isn't made. + */ +void fscrypt_destroy_keyring(struct super_block *sb) { - key_put(sb->s_master_keys); + struct fscrypt_keyring *keyring = sb->s_master_keys; + size_t i; + + if (!keyring) + return; + + for (i = 0; i < ARRAY_SIZE(keyring->key_hashtable); i++) { + struct hlist_head *bucket = &keyring->key_hashtable[i]; + struct fscrypt_master_key *mk; + struct hlist_node *tmp; + + hlist_for_each_entry_safe(mk, tmp, bucket, mk_node) { + /* + * Since all inodes were already evicted, every key + * remaining in the keyring should have an empty inode + * list, and should only still be in the keyring due to + * the single active ref associated with ->mk_secret. + * There should be no structural refs beyond the one + * associated with the active ref. + */ + WARN_ON(refcount_read(&mk->mk_active_refs) != 1); + WARN_ON(refcount_read(&mk->mk_struct_refs) != 1); + WARN_ON(!is_master_key_secret_present(&mk->mk_secret)); + wipe_master_key_secret(&mk->mk_secret); + fscrypt_put_master_key_activeref(mk); + } + } + kfree_sensitive(keyring); sb->s_master_keys = NULL; } +static struct hlist_head * +fscrypt_mk_hash_bucket(struct fscrypt_keyring *keyring, + const struct fscrypt_key_specifier *mk_spec) +{ + /* + * Since key specifiers should be "random" values, it is sufficient to + * use a trivial hash function that just takes the first several bits of + * the key specifier. + */ + unsigned long i = get_unaligned((unsigned long *)&mk_spec->u); + + return &keyring->key_hashtable[i % ARRAY_SIZE(keyring->key_hashtable)]; +} + /* - * Find the specified master key in ->s_master_keys. - * Returns ERR_PTR(-ENOKEY) if not found. + * Find the specified master key struct in ->s_master_keys and take a structural + * ref to it. The structural ref guarantees that the key struct continues to + * exist, but it does *not* guarantee that ->s_master_keys continues to contain + * the key struct. The structural ref needs to be dropped by + * fscrypt_put_master_key(). Returns NULL if the key struct is not found. */ -struct key *fscrypt_find_master_key(struct super_block *sb, - const struct fscrypt_key_specifier *mk_spec) +struct fscrypt_master_key * +fscrypt_find_master_key(struct super_block *sb, + const struct fscrypt_key_specifier *mk_spec) { - struct key *keyring; - char description[FSCRYPT_MK_DESCRIPTION_SIZE]; + struct fscrypt_keyring *keyring; + struct hlist_head *bucket; + struct fscrypt_master_key *mk; - /* pairs with smp_store_release() in allocate_filesystem_keyring() */ - keyring = READ_ONCE(sb->s_master_keys); + /* + * Pairs with the smp_store_release() in allocate_filesystem_keyring(). + * I.e., another task can publish ->s_master_keys concurrently, + * executing a RELEASE barrier. We need to use smp_load_acquire() here + * to safely ACQUIRE the memory the other task published. + */ + keyring = smp_load_acquire(&sb->s_master_keys); if (keyring == NULL) - return ERR_PTR(-ENOKEY); /* No keyring yet, so no keys yet. */ + return NULL; /* No keyring yet, so no keys yet. */ - format_mk_description(description, mk_spec); - return search_fscrypt_keyring(keyring, &key_type_fscrypt, description); + bucket = fscrypt_mk_hash_bucket(keyring, mk_spec); + rcu_read_lock(); + switch (mk_spec->type) { + case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: + hlist_for_each_entry_rcu(mk, bucket, mk_node) { + if (mk->mk_spec.type == + FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR && + memcmp(mk->mk_spec.u.descriptor, + mk_spec->u.descriptor, + FSCRYPT_KEY_DESCRIPTOR_SIZE) == 0 && + refcount_inc_not_zero(&mk->mk_struct_refs)) + goto out; + } + break; + case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER: + hlist_for_each_entry_rcu(mk, bucket, mk_node) { + if (mk->mk_spec.type == + FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER && + memcmp(mk->mk_spec.u.identifier, + mk_spec->u.identifier, + FSCRYPT_KEY_IDENTIFIER_SIZE) == 0 && + refcount_inc_not_zero(&mk->mk_struct_refs)) + goto out; + } + break; + } + mk = NULL; +out: + rcu_read_unlock(); + return mk; } static int allocate_master_key_users_keyring(struct fscrypt_master_key *mk) @@ -266,17 +346,30 @@ static int allocate_master_key_users_keyring(struct fscrypt_master_key *mk) static struct key *find_master_key_user(struct fscrypt_master_key *mk) { char description[FSCRYPT_MK_USER_DESCRIPTION_SIZE]; + key_ref_t keyref; format_mk_user_description(description, mk->mk_spec.u.identifier); - return search_fscrypt_keyring(mk->mk_users, &key_type_fscrypt_user, - description); + + /* + * We need to mark the keyring reference as "possessed" so that we + * acquire permission to search it, via the KEY_POS_SEARCH permission. + */ + keyref = keyring_search(make_key_ref(mk->mk_users, true /*possessed*/), + &key_type_fscrypt_user, description, false); + if (IS_ERR(keyref)) { + if (PTR_ERR(keyref) == -EAGAIN || /* not found */ + PTR_ERR(keyref) == -EKEYREVOKED) /* recently invalidated */ + keyref = ERR_PTR(-ENOKEY); + return ERR_CAST(keyref); + } + return key_ref_to_ptr(keyref); } /* * Give the current user a "key" in ->mk_users. This charges the user's quota * and marks the master key as added by the current user, so that it cannot be - * removed by another user with the key. Either the master key's key->sem must - * be held for write, or the master key must be still undergoing initialization. + * removed by another user with the key. Either ->mk_sem must be held for + * write, or the master key must be still undergoing initialization. */ static int add_master_key_user(struct fscrypt_master_key *mk) { @@ -298,7 +391,7 @@ static int add_master_key_user(struct fscrypt_master_key *mk) /* * Remove the current user's "key" from ->mk_users. - * The master key's key->sem must be held for write. + * ->mk_sem must be held for write. * * Returns 0 if removed, -ENOKEY if not found, or another -errno code. */ @@ -316,64 +409,49 @@ static int remove_master_key_user(struct fscrypt_master_key *mk) } /* - * Allocate a new fscrypt_master_key which contains the given secret, set it as - * the payload of a new 'struct key' of type fscrypt, and link the 'struct key' - * into the given keyring. Synchronized by fscrypt_add_key_mutex. + * Allocate a new fscrypt_master_key, transfer the given secret over to it, and + * insert it into sb->s_master_keys. */ -static int add_new_master_key(struct fscrypt_master_key_secret *secret, - const struct fscrypt_key_specifier *mk_spec, - struct key *keyring) +static int add_new_master_key(struct super_block *sb, + struct fscrypt_master_key_secret *secret, + const struct fscrypt_key_specifier *mk_spec) { + struct fscrypt_keyring *keyring = sb->s_master_keys; struct fscrypt_master_key *mk; - char description[FSCRYPT_MK_DESCRIPTION_SIZE]; - struct key *key; int err; mk = kzalloc(sizeof(*mk), GFP_KERNEL); if (!mk) return -ENOMEM; + mk->mk_sb = sb; + init_rwsem(&mk->mk_sem); + refcount_set(&mk->mk_struct_refs, 1); mk->mk_spec = *mk_spec; - move_master_key_secret(&mk->mk_secret, secret); - init_rwsem(&mk->mk_secret_sem); - - refcount_set(&mk->mk_refcount, 1); /* secret is present */ INIT_LIST_HEAD(&mk->mk_decrypted_inodes); spin_lock_init(&mk->mk_decrypted_inodes_lock); if (mk_spec->type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) { err = allocate_master_key_users_keyring(mk); if (err) - goto out_free_mk; + goto out_put; err = add_master_key_user(mk); if (err) - goto out_free_mk; + goto out_put; } - /* - * Note that we don't charge this key to anyone's quota, since when - * ->mk_users is in use those keys are charged instead, and otherwise - * (when ->mk_users isn't in use) only root can add these keys. - */ - format_mk_description(description, mk_spec); - key = key_alloc(&key_type_fscrypt, description, - GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), - KEY_POS_SEARCH | KEY_USR_SEARCH | KEY_USR_VIEW, - KEY_ALLOC_NOT_IN_QUOTA, NULL); - if (IS_ERR(key)) { - err = PTR_ERR(key); - goto out_free_mk; - } - err = key_instantiate_and_link(key, mk, sizeof(*mk), keyring, NULL); - key_put(key); - if (err) - goto out_free_mk; + move_master_key_secret(&mk->mk_secret, secret); + refcount_set(&mk->mk_active_refs, 1); /* ->mk_secret is present */ + spin_lock(&keyring->lock); + hlist_add_head_rcu(&mk->mk_node, + fscrypt_mk_hash_bucket(keyring, mk_spec)); + spin_unlock(&keyring->lock); return 0; -out_free_mk: - free_master_key(mk); +out_put: + fscrypt_put_master_key(mk); return err; } @@ -382,89 +460,105 @@ out_free_mk: static int add_existing_master_key(struct fscrypt_master_key *mk, struct fscrypt_master_key_secret *secret) { - struct key *mk_user; - bool rekey; int err; /* * If the current user is already in ->mk_users, then there's nothing to - * do. (Not applicable for v1 policy keys, which have NULL ->mk_users.) + * do. Otherwise, we need to add the user to ->mk_users. (Neither is + * applicable for v1 policy keys, which have NULL ->mk_users.) */ if (mk->mk_users) { - mk_user = find_master_key_user(mk); + struct key *mk_user = find_master_key_user(mk); + if (mk_user != ERR_PTR(-ENOKEY)) { if (IS_ERR(mk_user)) return PTR_ERR(mk_user); key_put(mk_user); return 0; } - } - - /* If we'll be re-adding ->mk_secret, try to take the reference. */ - rekey = !is_master_key_secret_present(&mk->mk_secret); - if (rekey && !refcount_inc_not_zero(&mk->mk_refcount)) - return KEY_DEAD; - - /* Add the current user to ->mk_users, if applicable. */ - if (mk->mk_users) { err = add_master_key_user(mk); - if (err) { - if (rekey && refcount_dec_and_test(&mk->mk_refcount)) - return KEY_DEAD; + if (err) return err; - } } /* Re-add the secret if needed. */ - if (rekey) { - down_write(&mk->mk_secret_sem); + if (!is_master_key_secret_present(&mk->mk_secret)) { + if (!refcount_inc_not_zero(&mk->mk_active_refs)) + return KEY_DEAD; move_master_key_secret(&mk->mk_secret, secret); - up_write(&mk->mk_secret_sem); } + return 0; } -static int add_master_key(struct super_block *sb, - struct fscrypt_master_key_secret *secret, - const struct fscrypt_key_specifier *mk_spec) +static int do_add_master_key(struct super_block *sb, + struct fscrypt_master_key_secret *secret, + const struct fscrypt_key_specifier *mk_spec) { static DEFINE_MUTEX(fscrypt_add_key_mutex); - struct key *key; + struct fscrypt_master_key *mk; int err; mutex_lock(&fscrypt_add_key_mutex); /* serialize find + link */ -retry: - key = fscrypt_find_master_key(sb, mk_spec); - if (IS_ERR(key)) { - err = PTR_ERR(key); - if (err != -ENOKEY) - goto out_unlock; + + mk = fscrypt_find_master_key(sb, mk_spec); + if (!mk) { /* Didn't find the key in ->s_master_keys. Add it. */ err = allocate_filesystem_keyring(sb); - if (err) - goto out_unlock; - err = add_new_master_key(secret, mk_spec, sb->s_master_keys); + if (!err) + err = add_new_master_key(sb, secret, mk_spec); } else { /* * Found the key in ->s_master_keys. Re-add the secret if * needed, and add the user to ->mk_users if needed. */ - down_write(&key->sem); - err = add_existing_master_key(key->payload.data[0], secret); - up_write(&key->sem); + down_write(&mk->mk_sem); + err = add_existing_master_key(mk, secret); + up_write(&mk->mk_sem); if (err == KEY_DEAD) { - /* Key being removed or needs to be removed */ - key_invalidate(key); - key_put(key); - goto retry; + /* + * We found a key struct, but it's already been fully + * removed. Ignore the old struct and add a new one. + * fscrypt_add_key_mutex means we don't need to worry + * about concurrent adds. + */ + err = add_new_master_key(sb, secret, mk_spec); } - key_put(key); + fscrypt_put_master_key(mk); } -out_unlock: mutex_unlock(&fscrypt_add_key_mutex); return err; } +static int add_master_key(struct super_block *sb, + struct fscrypt_master_key_secret *secret, + struct fscrypt_key_specifier *key_spec) +{ + int err; + + if (key_spec->type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) { + err = fscrypt_init_hkdf(&secret->hkdf, secret->raw, + secret->size); + if (err) + return err; + + /* + * Now that the HKDF context is initialized, the raw key is no + * longer needed. + */ + memzero_explicit(secret->raw, secret->size); + + /* Calculate the key identifier */ + err = fscrypt_hkdf_expand(&secret->hkdf, + HKDF_CONTEXT_KEY_IDENTIFIER, NULL, 0, + key_spec->u.identifier, + FSCRYPT_KEY_IDENTIFIER_SIZE); + if (err) + return err; + } + return do_add_master_key(sb, secret, key_spec); +} + static int fscrypt_provisioning_key_preparse(struct key_preparsed_payload *prep) { const struct fscrypt_provisioning_key_payload *payload = prep->data; @@ -491,7 +585,7 @@ static int fscrypt_provisioning_key_preparse(struct key_preparsed_payload *prep) static void fscrypt_provisioning_key_free_preparse( struct key_preparsed_payload *prep) { - kzfree(prep->payload.data[0]); + kfree_sensitive(prep->payload.data[0]); } static void fscrypt_provisioning_key_describe(const struct key *key, @@ -508,7 +602,7 @@ static void fscrypt_provisioning_key_describe(const struct key *key, static void fscrypt_provisioning_key_destroy(struct key *key) { - kzfree(key->payload.data[0]); + kfree_sensitive(key->payload.data[0]); } static struct key_type key_type_fscrypt_provisioning = { @@ -609,6 +703,15 @@ int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg) if (memchr_inv(arg.__reserved, 0, sizeof(arg.__reserved))) return -EINVAL; + /* + * Only root can add keys that are identified by an arbitrary descriptor + * rather than by a cryptographic hash --- since otherwise a malicious + * user could add the wrong key. + */ + if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR && + !capable(CAP_SYS_ADMIN)) + return -EACCES; + memset(&secret, 0, sizeof(secret)); if (arg.key_id) { if (arg.raw_size != 0) @@ -626,54 +729,86 @@ int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg) goto out_wipe_secret; } - switch (arg.key_spec.type) { - case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: - /* - * Only root can add keys that are identified by an arbitrary - * descriptor rather than by a cryptographic hash --- since - * otherwise a malicious user could add the wrong key. - */ - err = -EACCES; - if (!capable(CAP_SYS_ADMIN)) - goto out_wipe_secret; - break; - case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER: - err = fscrypt_init_hkdf(&secret.hkdf, secret.raw, secret.size); - if (err) - goto out_wipe_secret; - - /* - * Now that the HKDF context is initialized, the raw key is no - * longer needed. - */ - memzero_explicit(secret.raw, secret.size); - - /* Calculate the key identifier and return it to userspace. */ - err = fscrypt_hkdf_expand(&secret.hkdf, - HKDF_CONTEXT_KEY_IDENTIFIER, - NULL, 0, arg.key_spec.u.identifier, - FSCRYPT_KEY_IDENTIFIER_SIZE); - if (err) - goto out_wipe_secret; - err = -EFAULT; - if (copy_to_user(uarg->key_spec.u.identifier, - arg.key_spec.u.identifier, - FSCRYPT_KEY_IDENTIFIER_SIZE)) - goto out_wipe_secret; - break; - default: - WARN_ON(1); - err = -EINVAL; + err = add_master_key(sb, &secret, &arg.key_spec); + if (err) goto out_wipe_secret; - } - err = add_master_key(sb, &secret, &arg.key_spec); + /* Return the key identifier to userspace, if applicable */ + err = -EFAULT; + if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER && + copy_to_user(uarg->key_spec.u.identifier, arg.key_spec.u.identifier, + FSCRYPT_KEY_IDENTIFIER_SIZE)) + goto out_wipe_secret; + err = 0; out_wipe_secret: wipe_master_key_secret(&secret); return err; } EXPORT_SYMBOL_GPL(fscrypt_ioctl_add_key); +static void +fscrypt_get_test_dummy_secret(struct fscrypt_master_key_secret *secret) +{ + static u8 test_key[FSCRYPT_MAX_KEY_SIZE]; + + get_random_once(test_key, FSCRYPT_MAX_KEY_SIZE); + + memset(secret, 0, sizeof(*secret)); + secret->size = FSCRYPT_MAX_KEY_SIZE; + memcpy(secret->raw, test_key, FSCRYPT_MAX_KEY_SIZE); +} + +int fscrypt_get_test_dummy_key_identifier( + u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]) +{ + struct fscrypt_master_key_secret secret; + int err; + + fscrypt_get_test_dummy_secret(&secret); + + err = fscrypt_init_hkdf(&secret.hkdf, secret.raw, secret.size); + if (err) + goto out; + err = fscrypt_hkdf_expand(&secret.hkdf, HKDF_CONTEXT_KEY_IDENTIFIER, + NULL, 0, key_identifier, + FSCRYPT_KEY_IDENTIFIER_SIZE); +out: + wipe_master_key_secret(&secret); + return err; +} + +/** + * fscrypt_add_test_dummy_key() - add the test dummy encryption key + * @sb: the filesystem instance to add the key to + * @dummy_policy: the encryption policy for test_dummy_encryption + * + * If needed, add the key for the test_dummy_encryption mount option to the + * filesystem. To prevent misuse of this mount option, a per-boot random key is + * used instead of a hardcoded one. This makes it so that any encrypted files + * created using this option won't be accessible after a reboot. + * + * Return: 0 on success, -errno on failure + */ +int fscrypt_add_test_dummy_key(struct super_block *sb, + const struct fscrypt_dummy_policy *dummy_policy) +{ + const union fscrypt_policy *policy = dummy_policy->policy; + struct fscrypt_key_specifier key_spec; + struct fscrypt_master_key_secret secret; + int err; + + if (!policy) + return 0; + err = fscrypt_policy_to_key_spec(policy, &key_spec); + if (err) + return err; + fscrypt_get_test_dummy_secret(&secret); + err = add_master_key(sb, &secret, &key_spec); + wipe_master_key_secret(&secret); + return err; +} +EXPORT_SYMBOL_GPL(fscrypt_add_test_dummy_key); + /* * Verify that the current user has added a master key with the given identifier * (returns -ENOKEY if not). This is needed to prevent a user from encrypting @@ -694,19 +829,19 @@ int fscrypt_verify_key_added(struct super_block *sb, const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]) { struct fscrypt_key_specifier mk_spec; - struct key *key, *mk_user; struct fscrypt_master_key *mk; + struct key *mk_user; int err; mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER; memcpy(mk_spec.u.identifier, identifier, FSCRYPT_KEY_IDENTIFIER_SIZE); - key = fscrypt_find_master_key(sb, &mk_spec); - if (IS_ERR(key)) { - err = PTR_ERR(key); + mk = fscrypt_find_master_key(sb, &mk_spec); + if (!mk) { + err = -ENOKEY; goto out; } - mk = key->payload.data[0]; + down_read(&mk->mk_sem); mk_user = find_master_key_user(mk); if (IS_ERR(mk_user)) { err = PTR_ERR(mk_user); @@ -714,7 +849,8 @@ int fscrypt_verify_key_added(struct super_block *sb, key_put(mk_user); err = 0; } - key_put(key); + up_read(&mk->mk_sem); + fscrypt_put_master_key(mk); out: if (err == -ENOKEY && capable(CAP_FOWNER)) err = 0; @@ -776,6 +912,7 @@ static int check_for_busy_inodes(struct super_block *sb, struct list_head *pos; size_t busy_count = 0; unsigned long ino; + char ino_str[50] = ""; spin_lock(&mk->mk_decrypted_inodes_lock); @@ -797,11 +934,15 @@ static int check_for_busy_inodes(struct super_block *sb, } spin_unlock(&mk->mk_decrypted_inodes_lock); + /* If the inode is currently being created, ino may still be 0. */ + if (ino) + snprintf(ino_str, sizeof(ino_str), ", including ino %lu", ino); + fscrypt_warn(NULL, - "%s: %zu inode(s) still busy after removing key with %s %*phN, including ino %lu", + "%s: %zu inode(s) still busy after removing key with %s %*phN%s", sb->s_id, busy_count, master_key_spec_type(&mk->mk_spec), master_key_spec_len(&mk->mk_spec), (u8 *)&mk->mk_spec.u, - ino); + ino_str); return -EBUSY; } @@ -871,11 +1012,10 @@ static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users) struct super_block *sb = file_inode(filp)->i_sb; struct fscrypt_remove_key_arg __user *uarg = _uarg; struct fscrypt_remove_key_arg arg; - struct key *key; struct fscrypt_master_key *mk; u32 status_flags = 0; int err; - bool dead; + bool inodes_remain; if (copy_from_user(&arg, uarg, sizeof(arg))) return -EFAULT; @@ -895,12 +1035,10 @@ static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users) return -EACCES; /* Find the key being removed. */ - key = fscrypt_find_master_key(sb, &arg.key_spec); - if (IS_ERR(key)) - return PTR_ERR(key); - mk = key->payload.data[0]; - - down_write(&key->sem); + mk = fscrypt_find_master_key(sb, &arg.key_spec); + if (!mk) + return -ENOKEY; + down_write(&mk->mk_sem); /* If relevant, remove current user's (or all users) claim to the key */ if (mk->mk_users && mk->mk_users->keys.nr_leaves_on_tree != 0) { @@ -909,7 +1047,7 @@ static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users) else err = remove_master_key_user(mk); if (err) { - up_write(&key->sem); + up_write(&mk->mk_sem); goto out_put_key; } if (mk->mk_users->keys.nr_leaves_on_tree != 0) { @@ -921,28 +1059,22 @@ static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users) status_flags |= FSCRYPT_KEY_REMOVAL_STATUS_FLAG_OTHER_USERS; err = 0; - up_write(&key->sem); + up_write(&mk->mk_sem); goto out_put_key; } } /* No user claims remaining. Go ahead and wipe the secret. */ - dead = false; + err = -ENOKEY; if (is_master_key_secret_present(&mk->mk_secret)) { - down_write(&mk->mk_secret_sem); wipe_master_key_secret(&mk->mk_secret); - dead = refcount_dec_and_test(&mk->mk_refcount); - up_write(&mk->mk_secret_sem); - } - up_write(&key->sem); - if (dead) { - /* - * No inodes reference the key, and we wiped the secret, so the - * key object is free to be removed from the keyring. - */ - key_invalidate(key); + fscrypt_put_master_key_activeref(mk); err = 0; - } else { + } + inodes_remain = refcount_read(&mk->mk_active_refs) > 0; + up_write(&mk->mk_sem); + + if (inodes_remain) { /* Some inodes still reference this key; try to evict them. */ err = try_to_lock_encrypted_files(sb, mk); if (err == -EBUSY) { @@ -958,7 +1090,7 @@ static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users) * has been fully removed including all files locked. */ out_put_key: - key_put(key); + fscrypt_put_master_key(mk); if (err == 0) err = put_user(status_flags, &uarg->removal_status_flags); return err; @@ -1005,7 +1137,6 @@ int fscrypt_ioctl_get_key_status(struct file *filp, void __user *uarg) { struct super_block *sb = file_inode(filp)->i_sb; struct fscrypt_get_key_status_arg arg; - struct key *key; struct fscrypt_master_key *mk; int err; @@ -1022,19 +1153,18 @@ int fscrypt_ioctl_get_key_status(struct file *filp, void __user *uarg) arg.user_count = 0; memset(arg.__out_reserved, 0, sizeof(arg.__out_reserved)); - key = fscrypt_find_master_key(sb, &arg.key_spec); - if (IS_ERR(key)) { - if (key != ERR_PTR(-ENOKEY)) - return PTR_ERR(key); + mk = fscrypt_find_master_key(sb, &arg.key_spec); + if (!mk) { arg.status = FSCRYPT_KEY_STATUS_ABSENT; err = 0; goto out; } - mk = key->payload.data[0]; - down_read(&key->sem); + down_read(&mk->mk_sem); if (!is_master_key_secret_present(&mk->mk_secret)) { - arg.status = FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED; + arg.status = refcount_read(&mk->mk_active_refs) > 0 ? + FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED : + FSCRYPT_KEY_STATUS_ABSENT /* raced with full removal */; err = 0; goto out_release_key; } @@ -1056,8 +1186,8 @@ int fscrypt_ioctl_get_key_status(struct file *filp, void __user *uarg) } err = 0; out_release_key: - up_read(&key->sem); - key_put(key); + up_read(&mk->mk_sem); + fscrypt_put_master_key(mk); out: if (!err && copy_to_user(uarg, &arg, sizeof(arg))) err = -EFAULT; @@ -1069,13 +1199,9 @@ int __init fscrypt_init_keyring(void) { int err; - err = register_key_type(&key_type_fscrypt); - if (err) - return err; - err = register_key_type(&key_type_fscrypt_user); if (err) - goto err_unregister_fscrypt; + return err; err = register_key_type(&key_type_fscrypt_provisioning); if (err) @@ -1085,7 +1211,5 @@ int __init fscrypt_init_keyring(void) err_unregister_fscrypt_user: unregister_key_type(&key_type_fscrypt_user); -err_unregister_fscrypt: - unregister_key_type(&key_type_fscrypt); return err; } diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index 08c9f216a54d..f7407071a952 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -9,7 +9,7 @@ */ #include <crypto/skcipher.h> -#include <linux/key.h> +#include <linux/random.h> #include "fscrypt_private.h" @@ -18,38 +18,57 @@ struct fscrypt_mode fscrypt_modes[] = { .friendly_name = "AES-256-XTS", .cipher_str = "xts(aes)", .keysize = 64, + .security_strength = 32, .ivsize = 16, + .blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_256_XTS, }, [FSCRYPT_MODE_AES_256_CTS] = { .friendly_name = "AES-256-CTS-CBC", .cipher_str = "cts(cbc(aes))", .keysize = 32, + .security_strength = 32, .ivsize = 16, }, [FSCRYPT_MODE_AES_128_CBC] = { .friendly_name = "AES-128-CBC-ESSIV", .cipher_str = "essiv(cbc(aes),sha256)", .keysize = 16, + .security_strength = 16, .ivsize = 16, + .blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV, }, [FSCRYPT_MODE_AES_128_CTS] = { .friendly_name = "AES-128-CTS-CBC", .cipher_str = "cts(cbc(aes))", .keysize = 16, + .security_strength = 16, .ivsize = 16, }, [FSCRYPT_MODE_ADIANTUM] = { .friendly_name = "Adiantum", .cipher_str = "adiantum(xchacha12,aes)", .keysize = 32, + .security_strength = 32, + .ivsize = 32, + .blk_crypto_mode = BLK_ENCRYPTION_MODE_ADIANTUM, + }, + [FSCRYPT_MODE_AES_256_HCTR2] = { + .friendly_name = "AES-256-HCTR2", + .cipher_str = "hctr2(aes)", + .keysize = 32, + .security_strength = 32, .ivsize = 32, }, }; +static DEFINE_MUTEX(fscrypt_mode_key_setup_mutex); + static struct fscrypt_mode * select_encryption_mode(const union fscrypt_policy *policy, const struct inode *inode) { + BUILD_BUG_ON(ARRAY_SIZE(fscrypt_modes) != FSCRYPT_MODE_MAX + 1); + if (S_ISREG(inode->i_mode)) return &fscrypt_modes[fscrypt_policy_contents_mode(policy)]; @@ -62,9 +81,9 @@ select_encryption_mode(const union fscrypt_policy *policy, } /* Create a symmetric cipher object for the given encryption mode and key */ -struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode, - const u8 *raw_key, - const struct inode *inode) +static struct crypto_skcipher * +fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key, + const struct inode *inode) { struct crypto_skcipher *tfm; int err; @@ -81,7 +100,7 @@ struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode, mode->cipher_str, PTR_ERR(tfm)); return tfm; } - if (!xchg(&mode->logged_impl_name, 1)) { + if (!xchg(&mode->logged_cryptoapi_impl, 1)) { /* * fscrypt performance can vary greatly depending on which * crypto algorithm implementation is used. Help people debug @@ -107,42 +126,77 @@ err_free_tfm: return ERR_PTR(err); } -/* Given a per-file encryption key, set up the file's crypto transform object */ -int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key) +/* + * Prepare the crypto transform object or blk-crypto key in @prep_key, given the + * raw key, encryption mode (@ci->ci_mode), flag indicating which encryption + * implementation (fs-layer or blk-crypto) will be used (@ci->ci_inlinecrypt), + * and IV generation method (@ci->ci_policy.flags). + */ +int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key, + const u8 *raw_key, const struct fscrypt_info *ci) { struct crypto_skcipher *tfm; + if (fscrypt_using_inline_encryption(ci)) + return fscrypt_prepare_inline_crypt_key(prep_key, raw_key, ci); + tfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key, ci->ci_inode); if (IS_ERR(tfm)) return PTR_ERR(tfm); + /* + * Pairs with the smp_load_acquire() in fscrypt_is_key_prepared(). + * I.e., here we publish ->tfm with a RELEASE barrier so that + * concurrent tasks can ACQUIRE it. Note that this concurrency is only + * possible for per-mode keys, not for per-file keys. + */ + smp_store_release(&prep_key->tfm, tfm); + return 0; +} + +/* Destroy a crypto transform object and/or blk-crypto key. */ +void fscrypt_destroy_prepared_key(struct super_block *sb, + struct fscrypt_prepared_key *prep_key) +{ + crypto_free_skcipher(prep_key->tfm); + fscrypt_destroy_inline_crypt_key(sb, prep_key); + memzero_explicit(prep_key, sizeof(*prep_key)); +} - ci->ci_ctfm = tfm; +/* Given a per-file encryption key, set up the file's crypto transform object */ +int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key) +{ ci->ci_owns_key = true; - return 0; + return fscrypt_prepare_key(&ci->ci_enc_key, raw_key, ci); } static int setup_per_mode_enc_key(struct fscrypt_info *ci, struct fscrypt_master_key *mk, - struct crypto_skcipher **tfms, + struct fscrypt_prepared_key *keys, u8 hkdf_context, bool include_fs_uuid) { const struct inode *inode = ci->ci_inode; const struct super_block *sb = inode->i_sb; struct fscrypt_mode *mode = ci->ci_mode; const u8 mode_num = mode - fscrypt_modes; - struct crypto_skcipher *tfm, *prev_tfm; + struct fscrypt_prepared_key *prep_key; u8 mode_key[FSCRYPT_MAX_KEY_SIZE]; u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)]; unsigned int hkdf_infolen = 0; int err; - if (WARN_ON(mode_num > __FSCRYPT_MODE_MAX)) + if (WARN_ON(mode_num > FSCRYPT_MODE_MAX)) return -EINVAL; - /* pairs with cmpxchg() below */ - tfm = READ_ONCE(tfms[mode_num]); - if (likely(tfm != NULL)) - goto done; + prep_key = &keys[mode_num]; + if (fscrypt_is_key_prepared(prep_key, ci)) { + ci->ci_enc_key = *prep_key; + return 0; + } + + mutex_lock(&fscrypt_mode_key_setup_mutex); + + if (fscrypt_is_key_prepared(prep_key, ci)) + goto done_unlock; BUILD_BUG_ON(sizeof(mode_num) != 1); BUILD_BUG_ON(sizeof(sb->s_uuid) != 16); @@ -157,20 +211,42 @@ static int setup_per_mode_enc_key(struct fscrypt_info *ci, hkdf_context, hkdf_info, hkdf_infolen, mode_key, mode->keysize); if (err) - return err; - tfm = fscrypt_allocate_skcipher(mode, mode_key, inode); + goto out_unlock; + err = fscrypt_prepare_key(prep_key, mode_key, ci); memzero_explicit(mode_key, mode->keysize); - if (IS_ERR(tfm)) - return PTR_ERR(tfm); + if (err) + goto out_unlock; +done_unlock: + ci->ci_enc_key = *prep_key; + err = 0; +out_unlock: + mutex_unlock(&fscrypt_mode_key_setup_mutex); + return err; +} - /* pairs with READ_ONCE() above */ - prev_tfm = cmpxchg(&tfms[mode_num], NULL, tfm); - if (prev_tfm != NULL) { - crypto_free_skcipher(tfm); - tfm = prev_tfm; - } -done: - ci->ci_ctfm = tfm; +/* + * Derive a SipHash key from the given fscrypt master key and the given + * application-specific information string. + * + * Note that the KDF produces a byte array, but the SipHash APIs expect the key + * as a pair of 64-bit words. Therefore, on big endian CPUs we have to do an + * endianness swap in order to get the same results as on little endian CPUs. + */ +static int fscrypt_derive_siphash_key(const struct fscrypt_master_key *mk, + u8 context, const u8 *info, + unsigned int infolen, siphash_key_t *key) +{ + int err; + + err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, context, info, infolen, + (u8 *)key, sizeof(*key)); + if (err) + return err; + + BUILD_BUG_ON(sizeof(*key) != 16); + BUILD_BUG_ON(ARRAY_SIZE(key->key) != 2); + le64_to_cpus(&key->key[0]); + le64_to_cpus(&key->key[1]); return 0; } @@ -179,18 +255,68 @@ int fscrypt_derive_dirhash_key(struct fscrypt_info *ci, { int err; - err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, HKDF_CONTEXT_DIRHASH_KEY, - ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE, - (u8 *)&ci->ci_dirhash_key, - sizeof(ci->ci_dirhash_key)); + err = fscrypt_derive_siphash_key(mk, HKDF_CONTEXT_DIRHASH_KEY, + ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE, + &ci->ci_dirhash_key); if (err) return err; ci->ci_dirhash_key_initialized = true; return 0; } +void fscrypt_hash_inode_number(struct fscrypt_info *ci, + const struct fscrypt_master_key *mk) +{ + WARN_ON(ci->ci_inode->i_ino == 0); + WARN_ON(!mk->mk_ino_hash_key_initialized); + + ci->ci_hashed_ino = (u32)siphash_1u64(ci->ci_inode->i_ino, + &mk->mk_ino_hash_key); +} + +static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_info *ci, + struct fscrypt_master_key *mk) +{ + int err; + + err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_32_keys, + HKDF_CONTEXT_IV_INO_LBLK_32_KEY, true); + if (err) + return err; + + /* pairs with smp_store_release() below */ + if (!smp_load_acquire(&mk->mk_ino_hash_key_initialized)) { + + mutex_lock(&fscrypt_mode_key_setup_mutex); + + if (mk->mk_ino_hash_key_initialized) + goto unlock; + + err = fscrypt_derive_siphash_key(mk, + HKDF_CONTEXT_INODE_HASH_KEY, + NULL, 0, &mk->mk_ino_hash_key); + if (err) + goto unlock; + /* pairs with smp_load_acquire() above */ + smp_store_release(&mk->mk_ino_hash_key_initialized, true); +unlock: + mutex_unlock(&fscrypt_mode_key_setup_mutex); + if (err) + return err; + } + + /* + * New inodes may not have an inode number assigned yet. + * Hashing their inode number is delayed until later. + */ + if (ci->ci_inode->i_ino) + fscrypt_hash_inode_number(ci, mk); + return 0; +} + static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, - struct fscrypt_master_key *mk) + struct fscrypt_master_key *mk, + bool need_dirhash_key) { int err; @@ -203,7 +329,7 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, * encryption key. This ensures that the master key is * consistently used only for HKDF, avoiding key reuse issues. */ - err = setup_per_mode_enc_key(ci, mk, mk->mk_direct_tfms, + err = setup_per_mode_enc_key(ci, mk, mk->mk_direct_keys, HKDF_CONTEXT_DIRECT_KEY, false); } else if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) { @@ -211,18 +337,20 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, * IV_INO_LBLK_64: encryption keys are derived from (master_key, * mode_num, filesystem_uuid), and inode number is included in * the IVs. This format is optimized for use with inline - * encryption hardware compliant with the UFS or eMMC standards. + * encryption hardware compliant with the UFS standard. */ - err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_64_tfms, + err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_64_keys, HKDF_CONTEXT_IV_INO_LBLK_64_KEY, true); + } else if (ci->ci_policy.v2.flags & + FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) { + err = fscrypt_setup_iv_ino_lblk_32_key(ci, mk); } else { u8 derived_key[FSCRYPT_MAX_KEY_SIZE]; err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, HKDF_CONTEXT_PER_FILE_ENC_KEY, - ci->ci_nonce, - FS_KEY_DERIVATION_NONCE_SIZE, + ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE, derived_key, ci->ci_mode->keysize); if (err) return err; @@ -234,7 +362,7 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, return err; /* Derive a secret dirhash key for directories that need it. */ - if (S_ISDIR(ci->ci_inode->i_mode) && IS_CASEFOLDED(ci->ci_inode)) { + if (need_dirhash_key) { err = fscrypt_derive_dirhash_key(ci, mk); if (err) return err; @@ -244,46 +372,73 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, } /* + * Check whether the size of the given master key (@mk) is appropriate for the + * encryption settings which a particular file will use (@ci). + * + * If the file uses a v1 encryption policy, then the master key must be at least + * as long as the derived key, as this is a requirement of the v1 KDF. + * + * Otherwise, the KDF can accept any size key, so we enforce a slightly looser + * requirement: we require that the size of the master key be at least the + * maximum security strength of any algorithm whose key will be derived from it + * (but in practice we only need to consider @ci->ci_mode, since any other + * possible subkeys such as DIRHASH and INODE_HASH will never increase the + * required key size over @ci->ci_mode). This allows AES-256-XTS keys to be + * derived from a 256-bit master key, which is cryptographically sufficient, + * rather than requiring a 512-bit master key which is unnecessarily long. (We + * still allow 512-bit master keys if the user chooses to use them, though.) + */ +static bool fscrypt_valid_master_key_size(const struct fscrypt_master_key *mk, + const struct fscrypt_info *ci) +{ + unsigned int min_keysize; + + if (ci->ci_policy.version == FSCRYPT_POLICY_V1) + min_keysize = ci->ci_mode->keysize; + else + min_keysize = ci->ci_mode->security_strength; + + if (mk->mk_secret.size < min_keysize) { + fscrypt_warn(NULL, + "key with %s %*phN is too short (got %u bytes, need %u+ bytes)", + master_key_spec_type(&mk->mk_spec), + master_key_spec_len(&mk->mk_spec), + (u8 *)&mk->mk_spec.u, + mk->mk_secret.size, min_keysize); + return false; + } + return true; +} + +/* * Find the master key, then set up the inode's actual encryption key. * - * If the master key is found in the filesystem-level keyring, then the - * corresponding 'struct key' is returned in *master_key_ret with - * ->mk_secret_sem read-locked. This is needed to ensure that only one task - * links the fscrypt_info into ->mk_decrypted_inodes (as multiple tasks may race - * to create an fscrypt_info for the same inode), and to synchronize the master - * key being removed with a new inode starting to use it. + * If the master key is found in the filesystem-level keyring, then it is + * returned in *mk_ret with its semaphore read-locked. This is needed to ensure + * that only one task links the fscrypt_info into ->mk_decrypted_inodes (as + * multiple tasks may race to create an fscrypt_info for the same inode), and to + * synchronize the master key being removed with a new inode starting to use it. */ static int setup_file_encryption_key(struct fscrypt_info *ci, - struct key **master_key_ret) + bool need_dirhash_key, + struct fscrypt_master_key **mk_ret) { - struct key *key; - struct fscrypt_master_key *mk = NULL; struct fscrypt_key_specifier mk_spec; + struct fscrypt_master_key *mk; int err; - switch (ci->ci_policy.version) { - case FSCRYPT_POLICY_V1: - mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR; - memcpy(mk_spec.u.descriptor, - ci->ci_policy.v1.master_key_descriptor, - FSCRYPT_KEY_DESCRIPTOR_SIZE); - break; - case FSCRYPT_POLICY_V2: - mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER; - memcpy(mk_spec.u.identifier, - ci->ci_policy.v2.master_key_identifier, - FSCRYPT_KEY_IDENTIFIER_SIZE); - break; - default: - WARN_ON(1); - return -EINVAL; - } + err = fscrypt_select_encryption_impl(ci); + if (err) + return err; + + err = fscrypt_policy_to_key_spec(&ci->ci_policy, &mk_spec); + if (err) + return err; - key = fscrypt_find_master_key(ci->ci_inode->i_sb, &mk_spec); - if (IS_ERR(key)) { - if (key != ERR_PTR(-ENOKEY) || - ci->ci_policy.version != FSCRYPT_POLICY_V1) - return PTR_ERR(key); + mk = fscrypt_find_master_key(ci->ci_inode->i_sb, &mk_spec); + if (!mk) { + if (ci->ci_policy.version != FSCRYPT_POLICY_V1) + return -ENOKEY; /* * As a legacy fallback for v1 policies, search for the key in @@ -293,9 +448,7 @@ static int setup_file_encryption_key(struct fscrypt_info *ci, */ return fscrypt_setup_v1_file_key_via_subscribed_keyrings(ci); } - - mk = key->payload.data[0]; - down_read(&mk->mk_secret_sem); + down_read(&mk->mk_sem); /* Has the secret been removed (via FS_IOC_REMOVE_ENCRYPTION_KEY)? */ if (!is_master_key_secret_present(&mk->mk_secret)) { @@ -303,18 +456,7 @@ static int setup_file_encryption_key(struct fscrypt_info *ci, goto out_release_key; } - /* - * Require that the master key be at least as long as the derived key. - * Otherwise, the derived key cannot possibly contain as much entropy as - * that required by the encryption mode it will be used for. For v1 - * policies it's also required for the KDF to work at all. - */ - if (mk->mk_secret.size < ci->ci_mode->keysize) { - fscrypt_warn(NULL, - "key with %s %*phN is too short (got %u bytes, need %u+ bytes)", - master_key_spec_type(&mk_spec), - master_key_spec_len(&mk_spec), (u8 *)&mk_spec.u, - mk->mk_secret.size, ci->ci_mode->keysize); + if (!fscrypt_valid_master_key_size(mk, ci)) { err = -ENOKEY; goto out_release_key; } @@ -324,7 +466,7 @@ static int setup_file_encryption_key(struct fscrypt_info *ci, err = fscrypt_setup_v1_file_key(ci, mk->mk_secret.raw); break; case FSCRYPT_POLICY_V2: - err = fscrypt_setup_v2_file_key(ci, mk); + err = fscrypt_setup_v2_file_key(ci, mk, need_dirhash_key); break; default: WARN_ON(1); @@ -334,18 +476,18 @@ static int setup_file_encryption_key(struct fscrypt_info *ci, if (err) goto out_release_key; - *master_key_ret = key; + *mk_ret = mk; return 0; out_release_key: - up_read(&mk->mk_secret_sem); - key_put(key); + up_read(&mk->mk_sem); + fscrypt_put_master_key(mk); return err; } static void put_crypt_info(struct fscrypt_info *ci) { - struct key *key; + struct fscrypt_master_key *mk; if (!ci) return; @@ -353,97 +495,48 @@ static void put_crypt_info(struct fscrypt_info *ci) if (ci->ci_direct_key) fscrypt_put_direct_key(ci->ci_direct_key); else if (ci->ci_owns_key) - crypto_free_skcipher(ci->ci_ctfm); - - key = ci->ci_master_key; - if (key) { - struct fscrypt_master_key *mk = key->payload.data[0]; + fscrypt_destroy_prepared_key(ci->ci_inode->i_sb, + &ci->ci_enc_key); + mk = ci->ci_master_key; + if (mk) { /* * Remove this inode from the list of inodes that were unlocked - * with the master key. - * - * In addition, if we're removing the last inode from a key that - * already had its secret removed, invalidate the key so that it - * gets removed from ->s_master_keys. + * with the master key. In addition, if we're removing the last + * inode from a master key struct that already had its secret + * removed, then complete the full removal of the struct. */ spin_lock(&mk->mk_decrypted_inodes_lock); list_del(&ci->ci_master_key_link); spin_unlock(&mk->mk_decrypted_inodes_lock); - if (refcount_dec_and_test(&mk->mk_refcount)) - key_invalidate(key); - key_put(key); + fscrypt_put_master_key_activeref(mk); } memzero_explicit(ci, sizeof(*ci)); kmem_cache_free(fscrypt_info_cachep, ci); } -int fscrypt_get_encryption_info(struct inode *inode) +static int +fscrypt_setup_encryption_info(struct inode *inode, + const union fscrypt_policy *policy, + const u8 nonce[FSCRYPT_FILE_NONCE_SIZE], + bool need_dirhash_key) { struct fscrypt_info *crypt_info; - union fscrypt_context ctx; struct fscrypt_mode *mode; - struct key *master_key = NULL; + struct fscrypt_master_key *mk = NULL; int res; - if (fscrypt_has_encryption_key(inode)) - return 0; - res = fscrypt_initialize(inode->i_sb->s_cop->flags); if (res) return res; - res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); - if (res < 0) { - if (!fscrypt_dummy_context_enabled(inode) || - IS_ENCRYPTED(inode)) { - fscrypt_warn(inode, - "Error %d getting encryption context", - res); - return res; - } - /* Fake up a context for an unencrypted directory */ - memset(&ctx, 0, sizeof(ctx)); - ctx.version = FSCRYPT_CONTEXT_V1; - ctx.v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; - ctx.v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; - memset(ctx.v1.master_key_descriptor, 0x42, - FSCRYPT_KEY_DESCRIPTOR_SIZE); - res = sizeof(ctx.v1); - } - - crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_NOFS); + crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_KERNEL); if (!crypt_info) return -ENOMEM; crypt_info->ci_inode = inode; - - res = fscrypt_policy_from_context(&crypt_info->ci_policy, &ctx, res); - if (res) { - fscrypt_warn(inode, - "Unrecognized or corrupt encryption context"); - goto out; - } - - switch (ctx.version) { - case FSCRYPT_CONTEXT_V1: - memcpy(crypt_info->ci_nonce, ctx.v1.nonce, - FS_KEY_DERIVATION_NONCE_SIZE); - break; - case FSCRYPT_CONTEXT_V2: - memcpy(crypt_info->ci_nonce, ctx.v2.nonce, - FS_KEY_DERIVATION_NONCE_SIZE); - break; - default: - WARN_ON(1); - res = -EINVAL; - goto out; - } - - if (!fscrypt_supported_policy(&crypt_info->ci_policy, inode)) { - res = -EINVAL; - goto out; - } + crypt_info->ci_policy = *policy; + memcpy(crypt_info->ci_nonce, nonce, FSCRYPT_FILE_NONCE_SIZE); mode = select_encryption_mode(&crypt_info->ci_policy, inode); if (IS_ERR(mode)) { @@ -453,17 +546,24 @@ int fscrypt_get_encryption_info(struct inode *inode) WARN_ON(mode->ivsize > FSCRYPT_MAX_IV_SIZE); crypt_info->ci_mode = mode; - res = setup_file_encryption_key(crypt_info, &master_key); + res = setup_file_encryption_key(crypt_info, need_dirhash_key, &mk); if (res) goto out; + /* + * For existing inodes, multiple tasks may race to set ->i_crypt_info. + * So use cmpxchg_release(). This pairs with the smp_load_acquire() in + * fscrypt_get_info(). I.e., here we publish ->i_crypt_info with a + * RELEASE barrier so that other tasks can ACQUIRE it. + */ if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL) { - if (master_key) { - struct fscrypt_master_key *mk = - master_key->payload.data[0]; - - refcount_inc(&mk->mk_refcount); - crypt_info->ci_master_key = key_get(master_key); + /* + * We won the race and set ->i_crypt_info to our crypt_info. + * Now link it into the master key's inode list. + */ + if (mk) { + crypt_info->ci_master_key = mk; + refcount_inc(&mk->mk_active_refs); spin_lock(&mk->mk_decrypted_inodes_lock); list_add(&crypt_info->ci_master_key_link, &mk->mk_decrypted_inodes); @@ -473,21 +573,133 @@ int fscrypt_get_encryption_info(struct inode *inode) } res = 0; out: - if (master_key) { - struct fscrypt_master_key *mk = master_key->payload.data[0]; + if (mk) { + up_read(&mk->mk_sem); + fscrypt_put_master_key(mk); + } + put_crypt_info(crypt_info); + return res; +} - up_read(&mk->mk_secret_sem); - key_put(master_key); +/** + * fscrypt_get_encryption_info() - set up an inode's encryption key + * @inode: the inode to set up the key for. Must be encrypted. + * @allow_unsupported: if %true, treat an unsupported encryption policy (or + * unrecognized encryption context) the same way as the key + * being unavailable, instead of returning an error. Use + * %false unless the operation being performed is needed in + * order for files (or directories) to be deleted. + * + * Set up ->i_crypt_info, if it hasn't already been done. + * + * Note: unless ->i_crypt_info is already set, this isn't %GFP_NOFS-safe. So + * generally this shouldn't be called from within a filesystem transaction. + * + * Return: 0 if ->i_crypt_info was set or was already set, *or* if the + * encryption key is unavailable. (Use fscrypt_has_encryption_key() to + * distinguish these cases.) Also can return another -errno code. + */ +int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported) +{ + int res; + union fscrypt_context ctx; + union fscrypt_policy policy; + + if (fscrypt_has_encryption_key(inode)) + return 0; + + res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); + if (res < 0) { + if (res == -ERANGE && allow_unsupported) + return 0; + fscrypt_warn(inode, "Error %d getting encryption context", res); + return res; } + + res = fscrypt_policy_from_context(&policy, &ctx, res); + if (res) { + if (allow_unsupported) + return 0; + fscrypt_warn(inode, + "Unrecognized or corrupt encryption context"); + return res; + } + + if (!fscrypt_supported_policy(&policy, inode)) { + if (allow_unsupported) + return 0; + return -EINVAL; + } + + res = fscrypt_setup_encryption_info(inode, &policy, + fscrypt_context_nonce(&ctx), + IS_CASEFOLDED(inode) && + S_ISDIR(inode->i_mode)); + + if (res == -ENOPKG && allow_unsupported) /* Algorithm unavailable? */ + res = 0; if (res == -ENOKEY) res = 0; - put_crypt_info(crypt_info); return res; } -EXPORT_SYMBOL(fscrypt_get_encryption_info); /** - * fscrypt_put_encryption_info - free most of an inode's fscrypt data + * fscrypt_prepare_new_inode() - prepare to create a new inode in a directory + * @dir: a possibly-encrypted directory + * @inode: the new inode. ->i_mode must be set already. + * ->i_ino doesn't need to be set yet. + * @encrypt_ret: (output) set to %true if the new inode will be encrypted + * + * If the directory is encrypted, set up its ->i_crypt_info in preparation for + * encrypting the name of the new file. Also, if the new inode will be + * encrypted, set up its ->i_crypt_info and set *encrypt_ret=true. + * + * This isn't %GFP_NOFS-safe, and therefore it should be called before starting + * any filesystem transaction to create the inode. For this reason, ->i_ino + * isn't required to be set yet, as the filesystem may not have set it yet. + * + * This doesn't persist the new inode's encryption context. That still needs to + * be done later by calling fscrypt_set_context(). + * + * Return: 0 on success, -ENOKEY if the encryption key is missing, or another + * -errno code + */ +int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode, + bool *encrypt_ret) +{ + const union fscrypt_policy *policy; + u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; + + policy = fscrypt_policy_to_inherit(dir); + if (policy == NULL) + return 0; + if (IS_ERR(policy)) + return PTR_ERR(policy); + + if (WARN_ON_ONCE(inode->i_mode == 0)) + return -EINVAL; + + /* + * Only regular files, directories, and symlinks are encrypted. + * Special files like device nodes and named pipes aren't. + */ + if (!S_ISREG(inode->i_mode) && + !S_ISDIR(inode->i_mode) && + !S_ISLNK(inode->i_mode)) + return 0; + + *encrypt_ret = true; + + get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE); + return fscrypt_setup_encryption_info(inode, policy, nonce, + IS_CASEFOLDED(dir) && + S_ISDIR(inode->i_mode)); +} +EXPORT_SYMBOL_GPL(fscrypt_prepare_new_inode); + +/** + * fscrypt_put_encryption_info() - free most of an inode's fscrypt data + * @inode: an inode being evicted * * Free the inode's fscrypt_info. Filesystems must call this when the inode is * being evicted. An RCU grace period need not have elapsed yet. @@ -500,7 +712,8 @@ void fscrypt_put_encryption_info(struct inode *inode) EXPORT_SYMBOL(fscrypt_put_encryption_info); /** - * fscrypt_free_inode - free an inode's fscrypt data requiring RCU delay + * fscrypt_free_inode() - free an inode's fscrypt data requiring RCU delay + * @inode: an inode being freed * * Free the inode's cached decrypted symlink target, if any. Filesystems must * call this after an RCU grace period, just before they free the inode. @@ -515,7 +728,8 @@ void fscrypt_free_inode(struct inode *inode) EXPORT_SYMBOL(fscrypt_free_inode); /** - * fscrypt_drop_inode - check whether the inode's master key has been removed + * fscrypt_drop_inode() - check whether the inode's master key has been removed + * @inode: an inode being considered for eviction * * Filesystems supporting fscrypt must call this from their ->drop_inode() * method so that encrypted inodes are evicted as soon as they're no longer in @@ -525,8 +739,7 @@ EXPORT_SYMBOL(fscrypt_free_inode); */ int fscrypt_drop_inode(struct inode *inode) { - const struct fscrypt_info *ci = READ_ONCE(inode->i_crypt_info); - const struct fscrypt_master_key *mk; + const struct fscrypt_info *ci = fscrypt_get_info(inode); /* * If ci is NULL, then the inode doesn't have an encryption key set up @@ -536,7 +749,6 @@ int fscrypt_drop_inode(struct inode *inode) */ if (!ci || !ci->ci_master_key) return 0; - mk = ci->ci_master_key->payload.data[0]; /* * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes @@ -548,13 +760,13 @@ int fscrypt_drop_inode(struct inode *inode) return 0; /* - * Note: since we aren't holding ->mk_secret_sem, the result here can + * Note: since we aren't holding the key semaphore, the result here can * immediately become outdated. But there's no correctness problem with * unnecessarily evicting. Nor is there a correctness problem with not * evicting while iput() is racing with the key being removed, since * then the thread removing the key will either evict the inode itself * or will correctly detect that it wasn't evicted due to the race. */ - return !is_master_key_secret_present(&mk->mk_secret); + return !is_master_key_secret_present(&ci->ci_master_key->mk_secret); } EXPORT_SYMBOL_GPL(fscrypt_drop_inode); diff --git a/fs/crypto/keysetup_v1.c b/fs/crypto/keysetup_v1.c index 801b48c0cd7f..75dabd9b27f9 100644 --- a/fs/crypto/keysetup_v1.c +++ b/fs/crypto/keysetup_v1.c @@ -45,7 +45,7 @@ static DEFINE_SPINLOCK(fscrypt_direct_keys_lock); * key is longer, then only the first 'derived_keysize' bytes are used. */ static int derive_key_aes(const u8 *master_key, - const u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE], + const u8 nonce[FSCRYPT_FILE_NONCE_SIZE], u8 *derived_key, unsigned int derived_keysize) { int res = 0; @@ -60,7 +60,7 @@ static int derive_key_aes(const u8 *master_key, goto out; } crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); - req = skcipher_request_alloc(tfm, GFP_NOFS); + req = skcipher_request_alloc(tfm, GFP_KERNEL); if (!req) { res = -ENOMEM; goto out; @@ -68,7 +68,7 @@ static int derive_key_aes(const u8 *master_key, skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, crypto_req_done, &wait); - res = crypto_skcipher_setkey(tfm, nonce, FS_KEY_DERIVATION_NONCE_SIZE); + res = crypto_skcipher_setkey(tfm, nonce, FSCRYPT_FILE_NONCE_SIZE); if (res < 0) goto out; @@ -99,7 +99,7 @@ find_and_lock_process_key(const char *prefix, const struct user_key_payload *ukp; const struct fscrypt_key *payload; - description = kasprintf(GFP_NOFS, "%s%*phN", prefix, + description = kasprintf(GFP_KERNEL, "%s%*phN", prefix, FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor); if (!description) return ERR_PTR(-ENOMEM); @@ -143,10 +143,11 @@ invalid: /* Master key referenced by DIRECT_KEY policy */ struct fscrypt_direct_key { + struct super_block *dk_sb; struct hlist_node dk_node; refcount_t dk_refcount; const struct fscrypt_mode *dk_mode; - struct crypto_skcipher *dk_ctfm; + struct fscrypt_prepared_key dk_key; u8 dk_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE]; u8 dk_raw[FSCRYPT_MAX_KEY_SIZE]; }; @@ -154,8 +155,8 @@ struct fscrypt_direct_key { static void free_direct_key(struct fscrypt_direct_key *dk) { if (dk) { - crypto_free_skcipher(dk->dk_ctfm); - kzfree(dk); + fscrypt_destroy_prepared_key(dk->dk_sb, &dk->dk_key); + kfree_sensitive(dk); } } @@ -199,6 +200,8 @@ find_or_insert_direct_key(struct fscrypt_direct_key *to_insert, continue; if (ci->ci_mode != dk->dk_mode) continue; + if (!fscrypt_is_key_prepared(&dk->dk_key, ci)) + continue; if (crypto_memneq(raw_key, dk->dk_raw, ci->ci_mode->keysize)) continue; /* using existing tfm with same (descriptor, mode, raw_key) */ @@ -226,18 +229,15 @@ fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key) return dk; /* Nope, allocate one. */ - dk = kzalloc(sizeof(*dk), GFP_NOFS); + dk = kzalloc(sizeof(*dk), GFP_KERNEL); if (!dk) return ERR_PTR(-ENOMEM); + dk->dk_sb = ci->ci_inode->i_sb; refcount_set(&dk->dk_refcount, 1); dk->dk_mode = ci->ci_mode; - dk->dk_ctfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key, - ci->ci_inode); - if (IS_ERR(dk->dk_ctfm)) { - err = PTR_ERR(dk->dk_ctfm); - dk->dk_ctfm = NULL; + err = fscrypt_prepare_key(&dk->dk_key, raw_key, ci); + if (err) goto err_free_dk; - } memcpy(dk->dk_descriptor, ci->ci_policy.v1.master_key_descriptor, FSCRYPT_KEY_DESCRIPTOR_SIZE); memcpy(dk->dk_raw, raw_key, ci->ci_mode->keysize); @@ -259,7 +259,7 @@ static int setup_v1_file_key_direct(struct fscrypt_info *ci, if (IS_ERR(dk)) return PTR_ERR(dk); ci->ci_direct_key = dk; - ci->ci_ctfm = dk->dk_ctfm; + ci->ci_enc_key = dk->dk_key; return 0; } @@ -274,7 +274,7 @@ static int setup_v1_file_key_derived(struct fscrypt_info *ci, * This cannot be a stack buffer because it will be passed to the * scatterlist crypto API during derive_key_aes(). */ - derived_key = kmalloc(ci->ci_mode->keysize, GFP_NOFS); + derived_key = kmalloc(ci->ci_mode->keysize, GFP_KERNEL); if (!derived_key) return -ENOMEM; @@ -285,7 +285,7 @@ static int setup_v1_file_key_derived(struct fscrypt_info *ci, err = fscrypt_set_per_file_enc_key(ci, derived_key); out: - kzfree(derived_key); + kfree_sensitive(derived_key); return err; } diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index cf2a9d26ef7d..46757c3052ef 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -10,13 +10,17 @@ * Modified by Eric Biggers, 2019 for v2 policy support. */ +#include <linux/fs_context.h> #include <linux/random.h> +#include <linux/seq_file.h> #include <linux/string.h> #include <linux/mount.h> #include "fscrypt_private.h" /** - * fscrypt_policies_equal - check whether two encryption policies are the same + * fscrypt_policies_equal() - check whether two encryption policies are the same + * @policy1: the first policy + * @policy2: the second policy * * Return: %true if equal, else %false */ @@ -29,7 +33,35 @@ bool fscrypt_policies_equal(const union fscrypt_policy *policy1, return !memcmp(policy1, policy2, fscrypt_policy_size(policy1)); } -static bool fscrypt_valid_enc_modes(u32 contents_mode, u32 filenames_mode) +int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy, + struct fscrypt_key_specifier *key_spec) +{ + switch (policy->version) { + case FSCRYPT_POLICY_V1: + key_spec->type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR; + memcpy(key_spec->u.descriptor, policy->v1.master_key_descriptor, + FSCRYPT_KEY_DESCRIPTOR_SIZE); + return 0; + case FSCRYPT_POLICY_V2: + key_spec->type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER; + memcpy(key_spec->u.identifier, policy->v2.master_key_identifier, + FSCRYPT_KEY_IDENTIFIER_SIZE); + return 0; + default: + WARN_ON(1); + return -EINVAL; + } +} + +static const union fscrypt_policy * +fscrypt_get_dummy_policy(struct super_block *sb) +{ + if (!sb->s_cop->get_dummy_policy) + return NULL; + return sb->s_cop->get_dummy_policy(sb); +} + +static bool fscrypt_valid_enc_modes_v1(u32 contents_mode, u32 filenames_mode) { if (contents_mode == FSCRYPT_MODE_AES_256_XTS && filenames_mode == FSCRYPT_MODE_AES_256_CTS) @@ -46,6 +78,14 @@ static bool fscrypt_valid_enc_modes(u32 contents_mode, u32 filenames_mode) return false; } +static bool fscrypt_valid_enc_modes_v2(u32 contents_mode, u32 filenames_mode) +{ + if (contents_mode == FSCRYPT_MODE_AES_256_XTS && + filenames_mode == FSCRYPT_MODE_AES_256_HCTR2) + return true; + return fscrypt_valid_enc_modes_v1(contents_mode, filenames_mode); +} + static bool supported_direct_key_modes(const struct inode *inode, u32 contents_mode, u32 filenames_mode) { @@ -66,18 +106,28 @@ static bool supported_direct_key_modes(const struct inode *inode, return true; } -static bool supported_iv_ino_lblk_64_policy( - const struct fscrypt_policy_v2 *policy, - const struct inode *inode) +static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy, + const struct inode *inode, + const char *type, + int max_ino_bits, int max_lblk_bits) { struct super_block *sb = inode->i_sb; int ino_bits = 64, lblk_bits = 64; - if (policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) { + /* + * IV_INO_LBLK_* exist only because of hardware limitations, and + * currently the only known use case for them involves AES-256-XTS. + * That's also all we test currently. For these reasons, for now only + * allow AES-256-XTS here. This can be relaxed later if a use case for + * IV_INO_LBLK_* with other encryption modes arises. + */ + if (policy->contents_encryption_mode != FSCRYPT_MODE_AES_256_XTS) { fscrypt_warn(inode, - "The DIRECT_KEY and IV_INO_LBLK_64 flags are mutually exclusive"); + "Can't use %s policy with contents mode other than AES-256-XTS", + type); return false; } + /* * It's unsafe to include inode numbers in the IVs if the filesystem can * potentially renumber inodes, e.g. via filesystem shrinking. @@ -85,16 +135,22 @@ static bool supported_iv_ino_lblk_64_policy( if (!sb->s_cop->has_stable_inodes || !sb->s_cop->has_stable_inodes(sb)) { fscrypt_warn(inode, - "Can't use IV_INO_LBLK_64 policy on filesystem '%s' because it doesn't have stable inode numbers", - sb->s_id); + "Can't use %s policy on filesystem '%s' because it doesn't have stable inode numbers", + type, sb->s_id); return false; } if (sb->s_cop->get_ino_and_lblk_bits) sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits); - if (ino_bits > 32 || lblk_bits > 32) { + if (ino_bits > max_ino_bits) { fscrypt_warn(inode, - "Can't use IV_INO_LBLK_64 policy on filesystem '%s' because it doesn't use 32-bit inode and block numbers", - sb->s_id); + "Can't use %s policy on filesystem '%s' because its inode numbers are too long", + type, sb->s_id); + return false; + } + if (lblk_bits > max_lblk_bits) { + fscrypt_warn(inode, + "Can't use %s policy on filesystem '%s' because its block numbers are too long", + type, sb->s_id); return false; } return true; @@ -103,7 +159,7 @@ static bool supported_iv_ino_lblk_64_policy( static bool fscrypt_supported_v1_policy(const struct fscrypt_policy_v1 *policy, const struct inode *inode) { - if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode, + if (!fscrypt_valid_enc_modes_v1(policy->contents_encryption_mode, policy->filenames_encryption_mode)) { fscrypt_warn(inode, "Unsupported encryption modes (contents %d, filenames %d)", @@ -137,7 +193,9 @@ static bool fscrypt_supported_v1_policy(const struct fscrypt_policy_v1 *policy, static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy, const struct inode *inode) { - if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode, + int count = 0; + + if (!fscrypt_valid_enc_modes_v2(policy->contents_encryption_mode, policy->filenames_encryption_mode)) { fscrypt_warn(inode, "Unsupported encryption modes (contents %d, filenames %d)", @@ -146,19 +204,43 @@ static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy, return false; } - if (policy->flags & ~FSCRYPT_POLICY_FLAGS_VALID) { + if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK | + FSCRYPT_POLICY_FLAG_DIRECT_KEY | + FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 | + FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) { fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)", policy->flags); return false; } + count += !!(policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY); + count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64); + count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32); + if (count > 1) { + fscrypt_warn(inode, "Mutually exclusive encryption flags (0x%02x)", + policy->flags); + return false; + } + if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) && !supported_direct_key_modes(inode, policy->contents_encryption_mode, policy->filenames_encryption_mode)) return false; if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) && - !supported_iv_ino_lblk_64_policy(policy, inode)) + !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_64", + 32, 32)) + return false; + + /* + * IV_INO_LBLK_32 hashes the inode number, so in principle it can + * support any ino_bits. However, currently the inode number is gotten + * from inode::i_ino which is 'unsigned long'. So for now the + * implementation limit is 32 bits. + */ + if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && + !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_32", + 32, 32)) return false; if (memchr_inv(policy->__reserved, 0, sizeof(policy->__reserved))) { @@ -170,7 +252,9 @@ static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy, } /** - * fscrypt_supported_policy - check whether an encryption policy is supported + * fscrypt_supported_policy() - check whether an encryption policy is supported + * @policy_u: the encryption policy + * @inode: the inode on which the policy will be used * * Given an encryption policy, check whether all its encryption modes and other * settings are supported by this kernel on the given inode. (But we don't @@ -192,15 +276,19 @@ bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, } /** - * fscrypt_new_context_from_policy - create a new fscrypt_context from a policy + * fscrypt_new_context() - create a new fscrypt_context + * @ctx_u: output context + * @policy_u: input policy + * @nonce: nonce to use * * Create an fscrypt_context for an inode that is being assigned the given - * encryption policy. A new nonce is randomly generated. + * encryption policy. @nonce must be a new random nonce. * * Return: the size of the new context in bytes. */ -static int fscrypt_new_context_from_policy(union fscrypt_context *ctx_u, - const union fscrypt_policy *policy_u) +static int fscrypt_new_context(union fscrypt_context *ctx_u, + const union fscrypt_policy *policy_u, + const u8 nonce[FSCRYPT_FILE_NONCE_SIZE]) { memset(ctx_u, 0, sizeof(*ctx_u)); @@ -218,7 +306,7 @@ static int fscrypt_new_context_from_policy(union fscrypt_context *ctx_u, memcpy(ctx->master_key_descriptor, policy->master_key_descriptor, sizeof(ctx->master_key_descriptor)); - get_random_bytes(ctx->nonce, sizeof(ctx->nonce)); + memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE); return sizeof(*ctx); } case FSCRYPT_POLICY_V2: { @@ -234,7 +322,7 @@ static int fscrypt_new_context_from_policy(union fscrypt_context *ctx_u, memcpy(ctx->master_key_identifier, policy->master_key_identifier, sizeof(ctx->master_key_identifier)); - get_random_bytes(ctx->nonce, sizeof(ctx->nonce)); + memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE); return sizeof(*ctx); } } @@ -242,7 +330,11 @@ static int fscrypt_new_context_from_policy(union fscrypt_context *ctx_u, } /** - * fscrypt_policy_from_context - convert an fscrypt_context to an fscrypt_policy + * fscrypt_policy_from_context() - convert an fscrypt_context to + * an fscrypt_policy + * @policy_u: output policy + * @ctx_u: input context + * @ctx_size: size of input context in bytes * * Given an fscrypt_context, build the corresponding fscrypt_policy. * @@ -258,7 +350,7 @@ int fscrypt_policy_from_context(union fscrypt_policy *policy_u, { memset(policy_u, 0, sizeof(*policy_u)); - if (ctx_size <= 0 || ctx_size != fscrypt_context_size(ctx_u)) + if (!fscrypt_context_is_valid(ctx_u, ctx_size)) return -EINVAL; switch (ctx_u->version) { @@ -306,7 +398,7 @@ static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy) union fscrypt_context ctx; int ret; - ci = READ_ONCE(inode->i_crypt_info); + ci = fscrypt_get_info(inode); if (ci) { /* key available, use the cached policy */ *policy = ci->ci_policy; @@ -326,6 +418,7 @@ static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy) static int set_encryption_policy(struct inode *inode, const union fscrypt_policy *policy) { + u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; union fscrypt_context ctx; int ctxsize; int err; @@ -354,13 +447,17 @@ static int set_encryption_policy(struct inode *inode, policy->v2.master_key_identifier); if (err) return err; + if (policy->v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) + pr_warn_once("%s (pid %d) is setting an IV_INO_LBLK_32 encryption policy. This should only be used if there are certain hardware limitations.\n", + current->comm, current->pid); break; default: WARN_ON(1); return -EINVAL; } - ctxsize = fscrypt_new_context_from_policy(&ctx, policy); + get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE); + ctxsize = fscrypt_new_context(&ctx, policy, nonce); return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, NULL); } @@ -397,7 +494,7 @@ int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg) return -EFAULT; policy.version = version; - if (!inode_owner_or_capable(inode)) + if (!inode_owner_or_capable(&init_user_ns, inode)) return -EACCES; ret = mnt_want_write_file(filp); @@ -481,6 +578,25 @@ int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *uarg) } EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_policy_ex); +/* FS_IOC_GET_ENCRYPTION_NONCE: retrieve file's encryption nonce for testing */ +int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg) +{ + struct inode *inode = file_inode(filp); + union fscrypt_context ctx; + int ret; + + ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); + if (ret < 0) + return ret; + if (!fscrypt_context_is_valid(&ctx, ret)) + return -EINVAL; + if (copy_to_user(arg, fscrypt_context_nonce(&ctx), + FSCRYPT_FILE_NONCE_SIZE)) + return -EFAULT; + return 0; +} +EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_nonce); + /** * fscrypt_has_permitted_context() - is a file's encryption policy permitted * within its directory? @@ -503,7 +619,7 @@ EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_policy_ex); int fscrypt_has_permitted_context(struct inode *parent, struct inode *child) { union fscrypt_policy parent_policy, child_policy; - int err; + int err, err1, err2; /* No restrictions on file types which are never encrypted */ if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) && @@ -533,56 +649,208 @@ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child) * In any case, if an unexpected error occurs, fall back to "forbidden". */ - err = fscrypt_get_encryption_info(parent); + err = fscrypt_get_encryption_info(parent, true); if (err) return 0; - err = fscrypt_get_encryption_info(child); + err = fscrypt_get_encryption_info(child, true); if (err) return 0; - err = fscrypt_get_policy(parent, &parent_policy); - if (err) - return 0; + err1 = fscrypt_get_policy(parent, &parent_policy); + err2 = fscrypt_get_policy(child, &child_policy); - err = fscrypt_get_policy(child, &child_policy); - if (err) + /* + * Allow the case where the parent and child both have an unrecognized + * encryption policy, so that files with an unrecognized encryption + * policy can be deleted. + */ + if (err1 == -EINVAL && err2 == -EINVAL) + return 1; + + if (err1 || err2) return 0; return fscrypt_policies_equal(&parent_policy, &child_policy); } EXPORT_SYMBOL(fscrypt_has_permitted_context); +/* + * Return the encryption policy that new files in the directory will inherit, or + * NULL if none, or an ERR_PTR() on error. If the directory is encrypted, also + * ensure that its key is set up, so that the new filename can be encrypted. + */ +const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir) +{ + int err; + + if (IS_ENCRYPTED(dir)) { + err = fscrypt_require_key(dir); + if (err) + return ERR_PTR(err); + return &dir->i_crypt_info->ci_policy; + } + + return fscrypt_get_dummy_policy(dir->i_sb); +} + /** - * fscrypt_inherit_context() - Sets a child context from its parent - * @parent: Parent inode from which the context is inherited. - * @child: Child inode that inherits the context from @parent. - * @fs_data: private data given by FS. - * @preload: preload child i_crypt_info if true + * fscrypt_context_for_new_inode() - create an encryption context for a new inode + * @ctx: where context should be written + * @inode: inode from which to fetch policy and nonce + * + * Given an in-core "prepared" (via fscrypt_prepare_new_inode) inode, + * generate a new context and write it to ctx. ctx _must_ be at least + * FSCRYPT_SET_CONTEXT_MAX_SIZE bytes. + * + * Return: size of the resulting context or a negative error code. + */ +int fscrypt_context_for_new_inode(void *ctx, struct inode *inode) +{ + struct fscrypt_info *ci = inode->i_crypt_info; + + BUILD_BUG_ON(sizeof(union fscrypt_context) != + FSCRYPT_SET_CONTEXT_MAX_SIZE); + + /* fscrypt_prepare_new_inode() should have set up the key already. */ + if (WARN_ON_ONCE(!ci)) + return -ENOKEY; + + return fscrypt_new_context(ctx, &ci->ci_policy, ci->ci_nonce); +} +EXPORT_SYMBOL_GPL(fscrypt_context_for_new_inode); + +/** + * fscrypt_set_context() - Set the fscrypt context of a new inode + * @inode: a new inode + * @fs_data: private data given by FS and passed to ->set_context() + * + * This should be called after fscrypt_prepare_new_inode(), generally during a + * filesystem transaction. Everything here must be %GFP_NOFS-safe. * * Return: 0 on success, -errno on failure */ -int fscrypt_inherit_context(struct inode *parent, struct inode *child, - void *fs_data, bool preload) +int fscrypt_set_context(struct inode *inode, void *fs_data) { + struct fscrypt_info *ci = inode->i_crypt_info; union fscrypt_context ctx; int ctxsize; - struct fscrypt_info *ci; - int res; - res = fscrypt_get_encryption_info(parent); - if (res < 0) - return res; + ctxsize = fscrypt_context_for_new_inode(&ctx, inode); + if (ctxsize < 0) + return ctxsize; - ci = READ_ONCE(parent->i_crypt_info); - if (ci == NULL) - return -ENOKEY; + /* + * This may be the first time the inode number is available, so do any + * delayed key setup that requires the inode number. + */ + if (ci->ci_policy.version == FSCRYPT_POLICY_V2 && + (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) + fscrypt_hash_inode_number(ci, ci->ci_master_key); + + return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, fs_data); +} +EXPORT_SYMBOL_GPL(fscrypt_set_context); + +/** + * fscrypt_parse_test_dummy_encryption() - parse the test_dummy_encryption mount option + * @param: the mount option + * @dummy_policy: (input/output) the place to write the dummy policy that will + * result from parsing the option. Zero-initialize this. If a policy is + * already set here (due to test_dummy_encryption being given multiple + * times), then this function will verify that the policies are the same. + * + * Return: 0 on success; -EINVAL if the argument is invalid; -EEXIST if the + * argument conflicts with one already specified; or -ENOMEM. + */ +int fscrypt_parse_test_dummy_encryption(const struct fs_parameter *param, + struct fscrypt_dummy_policy *dummy_policy) +{ + const char *arg = "v2"; + union fscrypt_policy *policy; + int err; + + if (param->type == fs_value_is_string && *param->string) + arg = param->string; + + policy = kzalloc(sizeof(*policy), GFP_KERNEL); + if (!policy) + return -ENOMEM; + + if (!strcmp(arg, "v1")) { + policy->version = FSCRYPT_POLICY_V1; + policy->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; + policy->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; + memset(policy->v1.master_key_descriptor, 0x42, + FSCRYPT_KEY_DESCRIPTOR_SIZE); + } else if (!strcmp(arg, "v2")) { + policy->version = FSCRYPT_POLICY_V2; + policy->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; + policy->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; + err = fscrypt_get_test_dummy_key_identifier( + policy->v2.master_key_identifier); + if (err) + goto out; + } else { + err = -EINVAL; + goto out; + } + + if (dummy_policy->policy) { + if (fscrypt_policies_equal(policy, dummy_policy->policy)) + err = 0; + else + err = -EEXIST; + goto out; + } + dummy_policy->policy = policy; + policy = NULL; + err = 0; +out: + kfree(policy); + return err; +} +EXPORT_SYMBOL_GPL(fscrypt_parse_test_dummy_encryption); + +/** + * fscrypt_dummy_policies_equal() - check whether two dummy policies are equal + * @p1: the first test dummy policy (may be unset) + * @p2: the second test dummy policy (may be unset) + * + * Return: %true if the dummy policies are both set and equal, or both unset. + */ +bool fscrypt_dummy_policies_equal(const struct fscrypt_dummy_policy *p1, + const struct fscrypt_dummy_policy *p2) +{ + if (!p1->policy && !p2->policy) + return true; + if (!p1->policy || !p2->policy) + return false; + return fscrypt_policies_equal(p1->policy, p2->policy); +} +EXPORT_SYMBOL_GPL(fscrypt_dummy_policies_equal); + +/** + * fscrypt_show_test_dummy_encryption() - show '-o test_dummy_encryption' + * @seq: the seq_file to print the option to + * @sep: the separator character to use + * @sb: the filesystem whose options are being shown + * + * Show the test_dummy_encryption mount option, if it was specified. + * This is mainly used for /proc/mounts. + */ +void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep, + struct super_block *sb) +{ + const union fscrypt_policy *policy = fscrypt_get_dummy_policy(sb); + int vers; + + if (!policy) + return; - ctxsize = fscrypt_new_context_from_policy(&ctx, &ci->ci_policy); + vers = policy->version; + if (vers == FSCRYPT_POLICY_V1) /* Handle numbering quirk */ + vers = 1; - BUILD_BUG_ON(sizeof(ctx) != FSCRYPT_SET_CONTEXT_MAX_SIZE); - res = parent->i_sb->s_cop->set_context(child, &ctx, ctxsize, fs_data); - if (res) - return res; - return preload ? fscrypt_get_encryption_info(child): 0; + seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, vers); } -EXPORT_SYMBOL(fscrypt_inherit_context); +EXPORT_SYMBOL_GPL(fscrypt_show_test_dummy_encryption); |