From 74836ecbc5c7565d24a770917644e96af3e98d25 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Mon, 12 Jun 2023 12:00:47 -0700 Subject: 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 # for the IMA piece Link: https://lore.kernel.org/r/20230612190047.59755-1-ebiggers@kernel.org Signed-off-by: Eric Biggers --- security/integrity/ima/ima_api.c | 31 ++++++++++++------------------- 1 file changed, 12 insertions(+), 19 deletions(-) (limited to 'security/integrity/ima') 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); -- cgit v1.2.3