diff options
| -rw-r--r-- | fs/verity/Kconfig | 1 | ||||
| -rw-r--r-- | fs/verity/fsverity_private.h | 7 | ||||
| -rw-r--r-- | fs/verity/measure.c | 43 | ||||
| -rw-r--r-- | include/linux/fsverity.h | 18 |
4 files changed, 62 insertions, 7 deletions
diff --git a/fs/verity/Kconfig b/fs/verity/Kconfig index 24d1b54de807..54598cd80145 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 diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h index a7920434bae5..c6fb62e0ef1a 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 */ 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/include/linux/fsverity.h b/include/linux/fsverity.h index a7afc800bd8d..7af030fa3c36 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 +139,9 @@ 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_get_digest(struct inode *inode, + u8 digest[FS_VERITY_MAX_DIGEST_SIZE], + enum hash_algo *alg); /* open.c */ @@ -170,6 +181,13 @@ static inline int fsverity_ioctl_measure(struct file *filp, void __user *arg) return -EOPNOTSUPP; } +static inline int fsverity_get_digest(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) |