| From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
| From: Paul Lawrence <paullawrence@google.com> |
| Date: Mon, 26 Oct 2020 09:34:26 -0700 |
| Subject: NOUPSTREAM: ANDROID: fs-verity: Export function to check signatures |
| |
| Allows a file system to provide its own fs-verity implementation |
| but still to hook into the signature check and control file from |
| fs-verity |
| |
| [CPNOTE: 20/07/21] Lee: Requested an update from Paul via the OoT bug |
| [CPNOTE: 21/07/21] Lee: Depends on upstreaming of IncFS |
| |
| Bug: 160634504 |
| Bug: 170978993 |
| Test: incfs_test running on this + subsequent changes |
| Signed-off-by: Paul Lawrence <paullawrence@google.com> |
| Change-Id: I02020af460d62fa5eb459a083419208e175005e8 |
| --- |
| fs/verity/signature.c | 36 ++++++++++++++++++++++++++++++++---- |
| include/linux/fsverity.h | 14 ++++++++++++++ |
| 2 files changed, 46 insertions(+), 4 deletions(-) |
| |
| diff --git a/fs/verity/signature.c b/fs/verity/signature.c |
| --- a/fs/verity/signature.c |
| +++ b/fs/verity/signature.c |
| @@ -40,11 +40,38 @@ static struct key *fsverity_keyring; |
| int fsverity_verify_signature(const struct fsverity_info *vi, |
| const u8 *signature, size_t sig_size) |
| { |
| - const struct inode *inode = vi->inode; |
| - const struct fsverity_hash_alg *hash_alg = vi->tree_params.hash_alg; |
| + unsigned int digest_algorithm = |
| + vi->tree_params.hash_alg - fsverity_hash_algs; |
| + |
| + return __fsverity_verify_signature(vi->inode, signature, sig_size, |
| + vi->file_digest, digest_algorithm); |
| +} |
| + |
| +/** |
| + * __fsverity_verify_signature() - check a verity file's signature |
| + * @inode: the file's inode |
| + * @signature: the file's signature |
| + * @sig_size: size of @signature. Can be 0 if there is no signature |
| + * @file_digest: the file's digest |
| + * @digest_algorithm: the digest algorithm used |
| + * |
| + * Takes the file's digest and optional signature and verifies the signature |
| + * against the digest and the fs-verity keyring if appropriate |
| + * |
| + * Return: 0 on success (signature valid or not required); -errno on failure |
| + */ |
| +int __fsverity_verify_signature(const struct inode *inode, const u8 *signature, |
| + size_t sig_size, const u8 *file_digest, |
| + unsigned int digest_algorithm) |
| +{ |
| struct fsverity_formatted_digest *d; |
| + struct fsverity_hash_alg *hash_alg = fsverity_get_hash_alg(inode, |
| + digest_algorithm); |
| int err; |
| |
| + if (IS_ERR(hash_alg)) |
| + return PTR_ERR(hash_alg); |
| + |
| if (sig_size == 0) { |
| if (fsverity_require_signatures) { |
| fsverity_err(inode, |
| @@ -60,7 +87,7 @@ int fsverity_verify_signature(const struct fsverity_info *vi, |
| memcpy(d->magic, "FSVerity", 8); |
| d->digest_algorithm = cpu_to_le16(hash_alg - fsverity_hash_algs); |
| d->digest_size = cpu_to_le16(hash_alg->digest_size); |
| - memcpy(d->digest, vi->file_digest, hash_alg->digest_size); |
| + memcpy(d->digest, file_digest, hash_alg->digest_size); |
| |
| err = verify_pkcs7_signature(d, sizeof(*d) + hash_alg->digest_size, |
| signature, sig_size, fsverity_keyring, |
| @@ -83,9 +110,10 @@ int fsverity_verify_signature(const struct fsverity_info *vi, |
| } |
| |
| pr_debug("Valid signature for file digest %s:%*phN\n", |
| - hash_alg->name, hash_alg->digest_size, vi->file_digest); |
| + hash_alg->name, hash_alg->digest_size, file_digest); |
| return 0; |
| } |
| +EXPORT_SYMBOL_GPL(__fsverity_verify_signature); |
| |
| #ifdef CONFIG_SYSCTL |
| static struct ctl_table_header *fsverity_sysctl_header; |
| diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h |
| --- a/include/linux/fsverity.h |
| +++ b/include/linux/fsverity.h |
| @@ -233,4 +233,18 @@ static inline bool fsverity_active(const struct inode *inode) |
| return fsverity_get_info(inode) != NULL; |
| } |
| |
| +#ifdef CONFIG_FS_VERITY_BUILTIN_SIGNATURES |
| +int __fsverity_verify_signature(const struct inode *inode, const u8 *signature, |
| + size_t sig_size, const u8 *file_digest, |
| + unsigned int digest_algorithm); |
| +#else /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */ |
| +static inline int __fsverity_verify_signature(const struct inode *inode, |
| + const u8 *signature, size_t sig_size, |
| + const u8 *file_digest, |
| + unsigned int digest_algorithm) |
| +{ |
| + return 0; |
| +} |
| +#endif /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */ |
| + |
| #endif /* _LINUX_FSVERITY_H */ |