Define a function named fsverity_measure() to return the verity file digest and the associated hash algorithm (enum hash_algo). Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx> --- fs/verity/fsverity_private.h | 6 ----- fs/verity/measure.c | 49 ++++++++++++++++++++++++++++++++++++ include/linux/fsverity.h | 17 +++++++++++++ 3 files changed, 66 insertions(+), 6 deletions(-) diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h index a7920434bae5..54c5f0993541 100644 --- a/fs/verity/fsverity_private.h +++ b/fs/verity/fsverity_private.h @@ -26,12 +26,6 @@ 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 */ diff --git a/fs/verity/measure.c b/fs/verity/measure.c index f0d7b30c62db..98d8f6f2a2be 100644 --- a/fs/verity/measure.c +++ b/fs/verity/measure.c @@ -57,3 +57,52 @@ int fsverity_ioctl_measure(struct file *filp, void __user *_uarg) return 0; } EXPORT_SYMBOL_GPL(fsverity_ioctl_measure); + +/** + * fsverity_measure() - get a verity file's digest + * @inode: inode to get digest of + * @digest: pointer to the digest + * @alg: pointer to the hash algorithm enumeration + * + * Return the file hash algorithm, digest size, and digest of an fsverity + * protected file. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_measure(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); + *alg = HASH_ALGO__LAST; + + /* convert hash algorithm to hash_algo_name */ + for (i = 0; i < HASH_ALGO__LAST; i++) { + pr_debug("name %s hash_algo_name[%d] %s\n", + hash_alg->name, i, hash_algo_name[i]); + + if (!strcmp(hash_alg->name, hash_algo_name[i])) { + *alg = i; + break; + } + } + + /* Shouldn't happen */ + if (*alg == HASH_ALGO__LAST) + 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/include/linux/fsverity.h b/include/linux/fsverity.h index b568b3c7d095..11006b60713b 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -12,8 +12,16 @@ #define _LINUX_FSVERITY_H #include <linux/fs.h> +#include <crypto/hash_info.h> +#include <crypto/sha2.h> #include <uapi/linux/fsverity.h> +/* + * 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 + /* Verity operations for filesystems */ struct fsverity_operations { @@ -131,6 +139,8 @@ int fsverity_ioctl_enable(struct file *filp, const void __user *arg); /* measure.c */ int fsverity_ioctl_measure(struct file *filp, void __user *arg); +int fsverity_measure(struct inode *inode, u8 digest[FS_VERITY_MAX_DIGEST_SIZE], + enum hash_algo *alg); /* open.c */ @@ -170,6 +180,13 @@ static inline int fsverity_ioctl_measure(struct file *filp, void __user *arg) return -EOPNOTSUPP; } +static inline int fsverity_measure(struct inode *inode, + u8 digest[FS_VERITY_MAX_DIGEST_SIZE], + enum hash_algo *alg) +{ + return -EOPNOTSUPP; +} + /* open.c */ static inline int fsverity_file_open(struct inode *inode, struct file *filp) -- 2.27.0
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