diff options
Diffstat (limited to 'fs/verity')
| -rw-r--r-- | fs/verity/Kconfig | 11 | ||||
| -rw-r--r-- | fs/verity/enable.c | 33 | ||||
| -rw-r--r-- | fs/verity/fsverity_private.h | 15 | ||||
| -rw-r--r-- | fs/verity/measure.c | 43 | ||||
| -rw-r--r-- | fs/verity/open.c | 12 | ||||
| -rw-r--r-- | fs/verity/read_metadata.c | 11 | ||||
| -rw-r--r-- | fs/verity/verify.c | 18 |
7 files changed, 80 insertions, 63 deletions
diff --git a/fs/verity/Kconfig b/fs/verity/Kconfig index 24d1b54de807..aad1f1d998b9 100644 --- a/fs/verity/Kconfig +++ b/fs/verity/Kconfig @@ -3,6 +3,7 @@ config FS_VERITY bool "FS Verity (read-only file-based authenticity protection)" select CRYPTO + select CRYPTO_HASH_INFO # SHA-256 is implied as it's intended to be the default hash algorithm. # To avoid bloat, other wanted algorithms must be selected explicitly. # Note that CRYPTO_SHA256 denotes the generic C implementation, but @@ -13,11 +14,11 @@ config FS_VERITY help This option enables fs-verity. fs-verity is the dm-verity mechanism implemented at the file level. On supported - filesystems (currently EXT4 and F2FS), userspace can use an - ioctl to enable verity for a file, which causes the filesystem - to build a Merkle tree for the file. The filesystem will then - transparently verify any data read from the file against the - Merkle tree. The file is also made read-only. + filesystems (currently ext4, f2fs, and btrfs), userspace can + use an ioctl to enable verity for a file, which causes the + filesystem to build a Merkle tree for the file. The filesystem + will then transparently verify any data read from the file + against the Merkle tree. The file is also made read-only. This serves as an integrity check, but the availability of the Merkle tree root hash also allows efficiently supporting diff --git a/fs/verity/enable.c b/fs/verity/enable.c index 60a4372aa4d7..df6b499bf6a1 100644 --- a/fs/verity/enable.c +++ b/fs/verity/enable.c @@ -18,27 +18,26 @@ * Read a file data page for Merkle tree construction. Do aggressive readahead, * since we're sequentially reading the entire file. */ -static struct page *read_file_data_page(struct file *filp, pgoff_t index, +static struct page *read_file_data_page(struct file *file, pgoff_t index, struct file_ra_state *ra, unsigned long remaining_pages) { - struct page *page; + DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, index); + struct folio *folio; - page = find_get_page_flags(filp->f_mapping, index, FGP_ACCESSED); - if (!page || !PageUptodate(page)) { - if (page) - put_page(page); + folio = __filemap_get_folio(ractl.mapping, index, FGP_ACCESSED, 0); + if (!folio || !folio_test_uptodate(folio)) { + if (folio) + folio_put(folio); else - page_cache_sync_readahead(filp->f_mapping, ra, filp, - index, remaining_pages); - page = read_mapping_page(filp->f_mapping, index, NULL); - if (IS_ERR(page)) - return page; + page_cache_sync_ra(&ractl, remaining_pages); + folio = read_cache_folio(ractl.mapping, index, NULL, file); + if (IS_ERR(folio)) + return &folio->page; } - if (PageReadahead(page)) - page_cache_async_readahead(filp->f_mapping, ra, filp, page, - index, remaining_pages); - return page; + if (folio_test_readahead(folio)) + page_cache_async_ra(&ractl, folio, remaining_pages); + return folio_file_page(folio, index); } static int build_merkle_tree_level(struct file *filp, unsigned int level, @@ -202,7 +201,7 @@ static int enable_verity(struct file *filp, const struct fsverity_operations *vops = inode->i_sb->s_vop; struct merkle_tree_params params = { }; struct fsverity_descriptor *desc; - size_t desc_size = sizeof(*desc) + arg->sig_size; + size_t desc_size = struct_size(desc, signature, arg->sig_size); struct fsverity_info *vi; int err; @@ -281,7 +280,7 @@ static int enable_verity(struct file *filp, * from disk. This is simpler, and it serves as an extra check that the * metadata we're writing is valid before actually enabling verity. */ - vi = fsverity_create_info(inode, desc, desc_size); + vi = fsverity_create_info(inode, desc); if (IS_ERR(vi)) { err = PTR_ERR(vi); goto rollback; diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h index a7920434bae5..dbe1ce5b450a 100644 --- a/fs/verity/fsverity_private.h +++ b/fs/verity/fsverity_private.h @@ -14,7 +14,6 @@ #define pr_fmt(fmt) "fs-verity: " fmt -#include <crypto/sha2.h> #include <linux/fsverity.h> #include <linux/mempool.h> @@ -26,12 +25,6 @@ struct ahash_request; */ #define FS_VERITY_MAX_LEVELS 8 -/* - * Largest digest size among all hash algorithms supported by fs-verity. - * Currently assumed to be <= size of fsverity_descriptor::root_hash. - */ -#define FS_VERITY_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE - /* A hash algorithm supported by fs-verity */ struct fsverity_hash_alg { struct crypto_ahash *tfm; /* hash tfm, allocated on demand */ @@ -77,8 +70,6 @@ struct fsverity_info { const struct inode *inode; }; -/* Arbitrary limit to bound the kmalloc() size. Can be changed. */ -#define FS_VERITY_MAX_DESCRIPTOR_SIZE 16384 #define FS_VERITY_MAX_SIGNATURE_SIZE (FS_VERITY_MAX_DESCRIPTOR_SIZE - \ sizeof(struct fsverity_descriptor)) @@ -122,16 +113,14 @@ int fsverity_init_merkle_tree_params(struct merkle_tree_params *params, const u8 *salt, size_t salt_size); struct fsverity_info *fsverity_create_info(const struct inode *inode, - struct fsverity_descriptor *desc, - size_t desc_size); + struct fsverity_descriptor *desc); void fsverity_set_info(struct inode *inode, struct fsverity_info *vi); void fsverity_free_info(struct fsverity_info *vi); int fsverity_get_descriptor(struct inode *inode, - struct fsverity_descriptor **desc_ret, - size_t *desc_size_ret); + struct fsverity_descriptor **desc_ret); int __init fsverity_init_info_cache(void); void __init fsverity_exit_info_cache(void); diff --git a/fs/verity/measure.c b/fs/verity/measure.c index f0d7b30c62db..e99c00350c28 100644 --- a/fs/verity/measure.c +++ b/fs/verity/measure.c @@ -57,3 +57,46 @@ int fsverity_ioctl_measure(struct file *filp, void __user *_uarg) return 0; } EXPORT_SYMBOL_GPL(fsverity_ioctl_measure); + +/** + * fsverity_get_digest() - get a verity file's digest + * @inode: inode to get digest of + * @digest: (out) pointer to the digest + * @alg: (out) pointer to the hash algorithm enumeration + * + * Return the file hash algorithm and digest of an fsverity protected file. + * Assumption: before calling fsverity_get_digest(), the file must have been + * opened. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_get_digest(struct inode *inode, + u8 digest[FS_VERITY_MAX_DIGEST_SIZE], + enum hash_algo *alg) +{ + const struct fsverity_info *vi; + const struct fsverity_hash_alg *hash_alg; + int i; + + vi = fsverity_get_info(inode); + if (!vi) + return -ENODATA; /* not a verity file */ + + hash_alg = vi->tree_params.hash_alg; + memset(digest, 0, FS_VERITY_MAX_DIGEST_SIZE); + + /* convert the verity hash algorithm name to a hash_algo_name enum */ + i = match_string(hash_algo_name, HASH_ALGO__LAST, hash_alg->name); + if (i < 0) + return -EINVAL; + *alg = i; + + if (WARN_ON_ONCE(hash_alg->digest_size != hash_digest_size[*alg])) + return -EINVAL; + memcpy(digest, vi->file_digest, hash_alg->digest_size); + + pr_debug("file digest %s:%*phN\n", hash_algo_name[*alg], + hash_digest_size[*alg], digest); + + return 0; +} diff --git a/fs/verity/open.c b/fs/verity/open.c index 92df87f5fa38..81ff94442f7b 100644 --- a/fs/verity/open.c +++ b/fs/verity/open.c @@ -147,8 +147,7 @@ static int compute_file_digest(struct fsverity_hash_alg *hash_alg, * fsverity_descriptor must have already undergone basic validation. */ struct fsverity_info *fsverity_create_info(const struct inode *inode, - struct fsverity_descriptor *desc, - size_t desc_size) + struct fsverity_descriptor *desc) { struct fsverity_info *vi; int err; @@ -264,8 +263,7 @@ static bool validate_fsverity_descriptor(struct inode *inode, * the filesystem, and do basic validation of it. */ int fsverity_get_descriptor(struct inode *inode, - struct fsverity_descriptor **desc_ret, - size_t *desc_size_ret) + struct fsverity_descriptor **desc_ret) { int res; struct fsverity_descriptor *desc; @@ -297,7 +295,6 @@ int fsverity_get_descriptor(struct inode *inode, } *desc_ret = desc; - *desc_size_ret = res; return 0; } @@ -306,17 +303,16 @@ static int ensure_verity_info(struct inode *inode) { struct fsverity_info *vi = fsverity_get_info(inode); struct fsverity_descriptor *desc; - size_t desc_size; int err; if (vi) return 0; - err = fsverity_get_descriptor(inode, &desc, &desc_size); + err = fsverity_get_descriptor(inode, &desc); if (err) return err; - vi = fsverity_create_info(inode, desc, desc_size); + vi = fsverity_create_info(inode, desc); if (IS_ERR(vi)) { err = PTR_ERR(vi); goto out_free_desc; diff --git a/fs/verity/read_metadata.c b/fs/verity/read_metadata.c index 7e2d0c7bdf0d..2aefc5565152 100644 --- a/fs/verity/read_metadata.c +++ b/fs/verity/read_metadata.c @@ -53,14 +53,14 @@ static int fsverity_read_merkle_tree(struct inode *inode, break; } - virt = kmap(page); + virt = kmap_local_page(page); if (copy_to_user(buf, virt + offs_in_page, bytes_to_copy)) { - kunmap(page); + kunmap_local(virt); put_page(page); err = -EFAULT; break; } - kunmap(page); + kunmap_local(virt); put_page(page); retval += bytes_to_copy; @@ -101,7 +101,7 @@ static int fsverity_read_descriptor(struct inode *inode, size_t desc_size; int res; - res = fsverity_get_descriptor(inode, &desc, &desc_size); + res = fsverity_get_descriptor(inode, &desc); if (res) return res; @@ -119,10 +119,9 @@ static int fsverity_read_signature(struct inode *inode, void __user *buf, u64 offset, int length) { struct fsverity_descriptor *desc; - size_t desc_size; int res; - res = fsverity_get_descriptor(inode, &desc, &desc_size); + res = fsverity_get_descriptor(inode, &desc); if (res) return res; diff --git a/fs/verity/verify.c b/fs/verity/verify.c index 0adb970f4e73..bde8c9b7d25f 100644 --- a/fs/verity/verify.c +++ b/fs/verity/verify.c @@ -1,6 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 /* - * Data verification functions, i.e. hooks for ->readpages() + * Data verification functions, i.e. hooks for ->readahead() * * Copyright 2019 Google LLC */ @@ -39,16 +39,6 @@ static void hash_at_level(const struct merkle_tree_params *params, (params->log_blocksize - params->log_arity); } -/* Extract a hash from a hash page */ -static void extract_hash(struct page *hpage, unsigned int hoffset, - unsigned int hsize, u8 *out) -{ - void *virt = kmap_atomic(hpage); - - memcpy(out, virt + hoffset, hsize); - kunmap_atomic(virt); -} - static inline int cmp_hashes(const struct fsverity_info *vi, const u8 *want_hash, const u8 *real_hash, pgoff_t index, int level) @@ -129,7 +119,7 @@ static bool verify_page(struct inode *inode, const struct fsverity_info *vi, } if (PageChecked(hpage)) { - extract_hash(hpage, hoffset, hsize, _want_hash); + memcpy_from_page(_want_hash, hpage, hoffset, hsize); want_hash = _want_hash; put_page(hpage); pr_debug_ratelimited("Hash page already checked, want %s:%*phN\n", @@ -158,7 +148,7 @@ descend: if (err) goto out; SetPageChecked(hpage); - extract_hash(hpage, hoffset, hsize, _want_hash); + memcpy_from_page(_want_hash, hpage, hoffset, hsize); want_hash = _want_hash; put_page(hpage); pr_debug("Verified hash page at level %d, now want %s:%*phN\n", @@ -214,7 +204,7 @@ EXPORT_SYMBOL_GPL(fsverity_verify_page); * that fail verification are set to the Error state. Verification is skipped * for pages already in the Error state, e.g. due to fscrypt decryption failure. * - * This is a helper function for use by the ->readpages() method of filesystems + * This is a helper function for use by the ->readahead() method of filesystems * that issue bios to read data directly into the page cache. Filesystems that * populate the page cache without issuing bios (e.g. non block-based * filesystems) must instead call fsverity_verify_page() directly on each page. |