[PATCH v3 3/4] integrity: Refactor asymmetric_verify for reusability

Stefan Berger
2026-04-16T15:42:02Z

Refactor asymmetric_verify for reusability. Have it call
asymmetric_verify_common with the signature verification key and the
public_key structure as parameters. sigv3 support for ML-DSA will need to
check the public key type first to decide how to do the signature
verification and therefore will have these parameters available for
calling asymmetric_verify_common.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

---
v3:
- added kernel-doc
- NULL pointer check on asymmetric_key_public_key return value
---
security/integrity/digsig_asymmetric.c | 62 ++++++++++++++++++--------
1 file changed, 43 insertions(+), 19 deletions(-)

diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
index ed171a627d18..a4eb73bba6d2 100644
--- a/security/integrity/digsig_asymmetric.c
+++ b/security/integrity/digsig_asymmetric.c
@@ -79,18 +79,25 @@ static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid)
return key;
}

-int asymmetric_verify(struct key *keyring, const char *sig,
- int siglen, const char *data, int datalen)
+/**
+ * asymmetric_verify_common -- sigv2 and sigv3 common verify function
+ * @key: The key to use for signature verification; caller must free it
+ * @pk: The associated public key; must not be NULL
+ * @sig: The xattr signature
+ * @siglen: The length of the xattr signature; must be at least
+ * sizeof(struct signature_v2_hdr)
+ * @data: The data to verify the signature on
+ * @datalen: Length of @data
+ */
+static int asymmetric_verify_common(const struct key *key,
+ const struct public_key *pk,
+ const char *sig, int siglen,
+ const char *data, int datalen)
{
- struct public_key_signature pks;
struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
- const struct public_key *pk;
- struct key *key;
+ struct public_key_signature pks;
int ret;

- if (siglen <= sizeof(*hdr))
- return -EBADMSG;
-
siglen -= sizeof(*hdr);

if (siglen != be16_to_cpu(hdr->sig_size))
@@ -99,19 +106,9 @@ int asymmetric_verify(struct key *keyring, const char *sig,
if (hdr->hash_algo >= HASH_ALGO__LAST)
return -ENOPKG;

- key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid));
- if (IS_ERR(key))
- return PTR_ERR(key);
-
memset(&pks, 0, sizeof(pks));

pks.hash_algo = hash_algo_name[hdr->hash_algo];
-
- pk = asymmetric_key_public_key(key);
- if (!pk) {
- ret = -ENOKEY;
- goto out;
- }
pks.pkey_algo = pk->pkey_algo;
if (!strcmp(pk->pkey_algo, "rsa")) {
pks.encoding = "pkcs1";
@@ -131,11 +128,38 @@ int asymmetric_verify(struct key *keyring, const char *sig,
pks.s_size = siglen;
ret = verify_signature(key, &pks);
out:
- key_put(key);
pr_debug("%s() = %d\n", __func__, ret);
return ret;
}

+int asymmetric_verify(struct key *keyring, const char *sig,
+ int siglen, const char *data, int datalen)
+{
+ struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
+ const struct public_key *pk;
+ struct key *key;
+ int ret;
+
+ if (siglen <= sizeof(*hdr))
+ return -EBADMSG;
+
+ key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid));
+ if (IS_ERR(key))
+ return PTR_ERR(key);
+ pk = asymmetric_key_public_key(key);
+ if (!pk) {
+ ret = -ENOKEY;
+ goto out;
+ }
+
+ ret = asymmetric_verify_common(key, pk, sig, siglen, data, datalen);
+
+out:
+ key_put(key);
+
+ return ret;
+}
+
/*
* calc_file_id_hash - calculate the hash of the ima_file_id struct data
* @type: xattr type [enum evm_ima_xattr_type]
--
2.53.0