| Message ID | 20220109185517.312280-3-zohar@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ima: support fs-verity digests and signatures | expand |
Mimi, On Sun, Jan 09, 2022 at 01:55:13PM -0500, Mimi Zohar wrote: > Define a function named fsverity_get_digest() to return the verity file > digest and the associated hash algorithm (enum hash_algo). > > Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> > --- > fs/verity/Kconfig | 1 + > fs/verity/fsverity_private.h | 7 ------- > fs/verity/measure.c | 40 ++++++++++++++++++++++++++++++++++++ > include/linux/fsverity.h | 18 ++++++++++++++++ > 4 files changed, 59 insertions(+), 7 deletions(-) > > diff --git a/fs/verity/measure.c b/fs/verity/measure.c > index f0d7b30c62db..52906b2e5811 100644 > --- a/fs/verity/measure.c > +++ b/fs/verity/measure.c > @@ -57,3 +57,43 @@ 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. > + * > + * 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); > + *alg = HASH_ALGO__LAST; Perhaps this line is redundant (*alg is overwritten later) and would needlessly mangle output value in case of -EINVAL while it's being untouched on -ENODATA. Thanks, > + > + /* convert hash algorithm to hash_algo_name */ > + i = match_string(hash_algo_name, HASH_ALGO__LAST, hash_alg->name); > + if (i < 0) > + return -EINVAL; > + *alg = i; > + > + 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; > +}
Hi Vitaly, On Mon, 2022-01-10 at 03:47 +0300, Vitaly Chikunov wrote: > Mimi, > > On Sun, Jan 09, 2022 at 01:55:13PM -0500, Mimi Zohar wrote: > > Define a function named fsverity_get_digest() to return the verity file > > digest and the associated hash algorithm (enum hash_algo). > > > > Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> > > --- > > fs/verity/Kconfig | 1 + > > fs/verity/fsverity_private.h | 7 ------- > > fs/verity/measure.c | 40 ++++++++++++++++++++++++++++++++++++ > > include/linux/fsverity.h | 18 ++++++++++++++++ > > 4 files changed, 59 insertions(+), 7 deletions(-) > > > > diff --git a/fs/verity/measure.c b/fs/verity/measure.c > > index f0d7b30c62db..52906b2e5811 100644 > > --- a/fs/verity/measure.c > > +++ b/fs/verity/measure.c > > @@ -57,3 +57,43 @@ 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. > > + * > > + * 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); > > + *alg = HASH_ALGO__LAST; > > Perhaps this line is redundant (*alg is overwritten later) and would > needlessly mangle output value in case of -EINVAL while it's being > untouched on -ENODATA. > Thanks! Mimi > > > + > > + /* convert hash algorithm to hash_algo_name */ > > + i = match_string(hash_algo_name, HASH_ALGO__LAST, hash_alg->name); > > + if (i < 0) > > + return -EINVAL; > > + *alg = i; > > + > > + 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; > > +}
On Sun, Jan 09, 2022 at 01:55:13PM -0500, Mimi Zohar wrote: > Define a function named fsverity_get_digest() to return the verity file > digest and the associated hash algorithm (enum hash_algo). > > Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> > --- Acked-by: Eric Biggers <ebiggers@google.com> > +int fsverity_get_digest(struct inode *inode, > + u8 digest[FS_VERITY_MAX_DIGEST_SIZE], > + enum hash_algo *alg) There's some weird indentation here. - Eric
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..52906b2e5811 100644 --- a/fs/verity/measure.c +++ b/fs/verity/measure.c @@ -57,3 +57,43 @@ 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. + * + * 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); + *alg = HASH_ALGO__LAST; + + /* convert hash algorithm to hash_algo_name */ + i = match_string(hash_algo_name, HASH_ALGO__LAST, hash_alg->name); + if (i < 0) + return -EINVAL; + *alg = i; + + 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..9a1b70cc7318 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)
Define a function named fsverity_get_digest() to return the verity file digest and the associated hash algorithm (enum hash_algo). Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> --- fs/verity/Kconfig | 1 + fs/verity/fsverity_private.h | 7 ------- fs/verity/measure.c | 40 ++++++++++++++++++++++++++++++++++++ include/linux/fsverity.h | 18 ++++++++++++++++ 4 files changed, 59 insertions(+), 7 deletions(-)