// SPDX-License-Identifier: GPL-2.0-only /* * This contains encryption functions for per-file encryption. * * 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 #include #include #include #include #include #include "fscrypt_private.h" static unsigned int num_prealloc_crypto_pages = 32; module_param(num_prealloc_crypto_pages, uint, 0444); MODULE_PARM_DESC(num_prealloc_crypto_pages, "Number of crypto pages to preallocate"); static mempool_t *fscrypt_bounce_page_pool = NULL; static struct workqueue_struct *fscrypt_read_workqueue; static DEFINE_MUTEX(fscrypt_init_mutex); struct kmem_cache *fscrypt_info_cachep; void fscrypt_enqueue_decrypt_work(struct work_struct *work) { queue_work(fscrypt_read_workqueue, work); } EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work); struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags) { return mempool_alloc(fscrypt_bounce_page_pool, 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. */ void fscrypt_free_bounce_page(struct page *bounce_page) { if (!bounce_page) return; set_page_private(bounce_page, (unsigned long)NULL); ClearPagePrivate(bounce_page); mempool_free(bounce_page, fscrypt_bounce_page_pool); } EXPORT_SYMBOL(fscrypt_free_bounce_page); void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, const struct fscrypt_info *ci) { u8 flags = fscrypt_policy_flags(&ci->ci_policy); memset(iv, 0, ci->ci_mode->ivsize); if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) { 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, FSCRYPT_FILE_NONCE_SIZE); } iv->lblk_num = cpu_to_le64(lblk_num); } /* Encrypt or decrypt a single filesystem block of file contents */ 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) { union fscrypt_iv iv; struct skcipher_request *req = NULL; DECLARE_CRYPTO_WAIT(wait); struct scatterlist dst, src; struct fscrypt_info *ci = inode->i_crypt_info; 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)) return -EINVAL; fscrypt_generate_iv(&iv, lblk_num, ci); req = skcipher_request_alloc(tfm, gfp_flags); if (!req) return -ENOMEM; skcipher_request_set_callback( req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, crypto_req_done, &wait); sg_init_table(&dst, 1); sg_set_page(&dst, dest_page, len, offs); sg_init_table(&src, 1); sg_set_page(&src, src_page, len, offs); skcipher_request_set_crypt(req, &src, &dst, len, &iv); if (rw == FS_DECRYPT) res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait); else res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait); skcipher_request_free(req); if (res) { fscrypt_err(inode, "%scryption failed for block %llu: %d", (rw == FS_DECRYPT ? "De" : "En"), lblk_num, res); return res; } return 0; } /** * 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. * @offs: Byte offset within @page of the first block to encrypt. Must be * a multiple of the filesystem's block size. * @gfp_flags: Memory allocation flags. See details below. * * A new bounce page is allocated, and the specified block(s) are encrypted into * it. In the bounce page, the ciphertext block(s) will be located at the same * offsets at which the plaintext block(s) were located in the source page; any * other parts of the bounce page will be left uninitialized. However, normally * blocksize == PAGE_SIZE and the whole page is encrypted at once. * * This is for use by the filesystem's ->writepages() method. * * The bounce page allocation is mempool-backed, so it will always succeed when * @gfp_flags includes __GFP_DIRECT_RECLAIM, e.g. when it's GFP_NOFS. However, * only the first page of each bio can be allocated this way. To prevent * deadlocks, for any additional pages a mask like GFP_NOWAIT must be used. * * Return: the new encrypted bounce page on success; an ERR_PTR() on failure */ struct page *fscrypt_encrypt_pagecache_blocks(struct page *page, unsigned int len, unsigned int offs, gfp_t gfp_flags) { const struct inode *inode = page->mapping->host; const unsigned int blockbits = inode->i_blkbits; const unsigned int blocksize = 1 << blockbits; struct page *ciphertext_page; u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) + (offs >> blockbits); unsigned int i; int err; if (WARN_ON_ONCE(!PageLocked(page))) return ERR_PTR(-EINVAL); if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize))) return ERR_PTR(-EINVAL); ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags); if (!ciphertext_page) return ERR_PTR(-ENOMEM); for (i = offs; i < offs + len; i += blocksize, lblk_num++) { err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page, ciphertext_page, blocksize, i, gfp_flags); if (err) { fscrypt_free_bounce_page(ciphertext_page); return ERR_PTR(err); } } SetPagePrivate(ciphertext_page); set_page_private(ciphertext_page, (unsigned long)page); return ciphertext_page; } 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. * @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 * @gfp_flags: Memory allocation flags * * Encrypt a possibly-compressed filesystem block that is located in an * arbitrary page, not necessarily in the original pagecache page. The @inode * and @lblk_num must be specified, as they can't be determined from @page. * * Return: 0 on success; -errno on failure */ int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page, unsigned int len, unsigned int offs, u64 lblk_num, gfp_t gfp_flags) { return fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page, page, len, offs, gfp_flags); } EXPORT_SYMBOL(fscrypt_encrypt_block_inplace); /** * 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. * @offs: Byte offset within @page of the first block to decrypt. Must be * a multiple of the filesystem's block size. * * The specified block(s) are decrypted in-place within the pagecache page, * 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. * * Return: 0 on success; -errno on failure */ int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len, unsigned int offs) { const struct inode *inode = page->mapping->host; const unsigned int blockbits = inode->i_blkbits; const unsigned int blocksize = 1 << blockbits; u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) + (offs >> blockbits); unsigned int i; int err; if (WARN_ON_ONCE(!PageLocked(page))) return -EINVAL; if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize))) return -EINVAL; for (i = offs; i < offs + len; i += blocksize, lblk_num++) { err = fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page, blocksize, i, GFP_NOFS); if (err) return err; } return 0; } 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. * @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 * * Decrypt a possibly-compressed filesystem block that is located in an * arbitrary page, not necessarily in the original pagecache page. The @inode * and @lblk_num must be specified, as they can't be determined from @page. * * Return: 0 on success; -errno on failure */ int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page, unsigned int len, unsigned int offs, u64 lblk_num) { return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page, len, offs, GFP_NOFS); } EXPORT_SYMBOL(fscrypt_decrypt_block_inplace); /** * fscrypt_initialize() - allocate major buffers for fs encryption. * @cop_flags: fscrypt operations flags * * We only call this when we start accessing encrypted files, since it * results in memory getting allocated that wouldn't otherwise be used. * * Return: 0 on success; -errno on failure */ int fscrypt_initialize(unsigned int cop_flags) { int err = 0; /* No need to allocate a bounce page pool if this FS won't use it. */ if (cop_flags & FS_CFLG_OWN_PAGES) return 0; mutex_lock(&fscrypt_init_mutex); if (fscrypt_bounce_page_pool) goto out_unlock; err = -ENOMEM; fscrypt_bounce_page_pool = mempool_create_page_pool(num_prealloc_crypto_pages, 0); if (!fscrypt_bounce_page_pool) goto out_unlock; err = 0; out_unlock: mutex_unlock(&fscrypt_init_mutex); return err; } void fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...) { static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); struct va_format vaf; va_list args; if (!__ratelimit(&rs)) return; va_start(args, fmt); vaf.fmt = fmt; vaf.va = &args; 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); } /** * fscrypt_init() - Set up for fs encryption. * * Return: 0 on success; -errno on failure */ static int __init fscrypt_init(void) { int err = -ENOMEM; /* * Use an unbound workqueue to allow bios to be decrypted in parallel * even when they happen to complete on the same CPU. This sacrifices * locality, but it's worthwhile since decryption is CPU-intensive. * * Also use a high-priority workqueue to prioritize decryption work, * which blocks reads from completing, over regular application tasks. */ fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue", WQ_UNBOUND | WQ_HIGHPRI, num_online_cpus()); if (!fscrypt_read_workqueue) goto fail; fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT); if (!fscrypt_info_cachep) goto fail_free_queue; err = fscrypt_init_keyring(); if (err) goto fail_free_info; return 0; fail_free_info: kmem_cache_destroy(fscrypt_info_cachep); fail_free_queue: destroy_workqueue(fscrypt_read_workqueue); fail: return err; } late_initcall(fscrypt_init)