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author | Eric Biggers <ebiggers@google.com> | 2023-06-12 21:00:47 +0200 |
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committer | Eric Biggers <ebiggers@google.com> | 2023-06-14 19:41:07 +0200 |
commit | 74836ecbc5c7565d24a770917644e96af3e98d25 (patch) | |
tree | 097ae681bdb906c38d3da394b388fc17de5b71e3 /security | |
parent | fsverity: simplify error handling in verify_data_block() (diff) | |
download | linux-74836ecbc5c7565d24a770917644e96af3e98d25.tar.xz linux-74836ecbc5c7565d24a770917644e96af3e98d25.zip |
fsverity: rework fsverity_get_digest() again
Address several issues with the calling convention and documentation of
fsverity_get_digest():
- Make it provide the hash algorithm as either a FS_VERITY_HASH_ALG_*
value or HASH_ALGO_* value, at the caller's choice, rather than only a
HASH_ALGO_* value as it did before. This allows callers to work with
the fsverity native algorithm numbers if they want to. HASH_ALGO_* is
what IMA uses, but other users (e.g. overlayfs) should use
FS_VERITY_HASH_ALG_* to match fsverity-utils and the fsverity UAPI.
- Make it return the digest size so that it doesn't need to be looked up
separately. Use the return value for this, since 0 works nicely for
the "file doesn't have fsverity enabled" case. This also makes it
clear that no other errors are possible.
- Rename the 'digest' parameter to 'raw_digest' and clearly document
that it is only useful in combination with the algorithm ID. This
hopefully clears up a point of confusion.
- Export it to modules, since overlayfs will need it for checking the
fsverity digests of lowerdata files
(https://lore.kernel.org/r/dd294a44e8f401e6b5140029d8355f88748cd8fd.1686565330.git.alexl@redhat.com).
Acked-by: Mimi Zohar <zohar@linux.ibm.com> # for the IMA piece
Link: https://lore.kernel.org/r/20230612190047.59755-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Diffstat (limited to 'security')
-rw-r--r-- | security/integrity/ima/ima_api.c | 31 |
1 files changed, 12 insertions, 19 deletions
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index d3662f4acadc..ce541b0ee1d3 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -202,19 +202,19 @@ int ima_get_action(struct mnt_idmap *idmap, struct inode *inode, allowed_algos); } -static int ima_get_verity_digest(struct integrity_iint_cache *iint, - struct ima_max_digest_data *hash) +static bool ima_get_verity_digest(struct integrity_iint_cache *iint, + struct ima_max_digest_data *hash) { - enum hash_algo verity_alg; - int ret; + enum hash_algo alg; + int digest_len; /* * On failure, 'measure' policy rules will result in a file data * hash containing 0's. */ - ret = fsverity_get_digest(iint->inode, hash->digest, &verity_alg); - if (ret) - return ret; + digest_len = fsverity_get_digest(iint->inode, hash->digest, NULL, &alg); + if (digest_len == 0) + return false; /* * Unlike in the case of actually calculating the file hash, in @@ -223,9 +223,9 @@ static int ima_get_verity_digest(struct integrity_iint_cache *iint, * mismatch between the verity algorithm and the xattr signature * algorithm, if one exists, will be detected later. */ - hash->hdr.algo = verity_alg; - hash->hdr.length = hash_digest_size[verity_alg]; - return 0; + hash->hdr.algo = alg; + hash->hdr.length = digest_len; + return true; } /* @@ -276,16 +276,9 @@ int ima_collect_measurement(struct integrity_iint_cache *iint, memset(&hash.digest, 0, sizeof(hash.digest)); if (iint->flags & IMA_VERITY_REQUIRED) { - result = ima_get_verity_digest(iint, &hash); - switch (result) { - case 0: - break; - case -ENODATA: + if (!ima_get_verity_digest(iint, &hash)) { audit_cause = "no-verity-digest"; - break; - default: - audit_cause = "invalid-verity-digest"; - break; + result = -ENODATA; } } else if (buf) { result = ima_calc_buffer_hash(buf, size, &hash.hdr); |