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 <[email protected]>
---
 security/integrity/digsig_asymmetric.c | 42 +++++++++++++++++---------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/security/integrity/digsig_asymmetric.c 
b/security/integrity/digsig_asymmetric.c
index 6e68ec3becbd..e29ed73f15cd 100644
--- a/security/integrity/digsig_asymmetric.c
+++ b/security/integrity/digsig_asymmetric.c
@@ -79,18 +79,15 @@ 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)
+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))
@@ -99,15 +96,10 @@ 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);
        pks.pkey_algo = pk->pkey_algo;
        if (!strcmp(pk->pkey_algo, "rsa")) {
                pks.encoding = "pkcs1";
@@ -127,11 +119,33 @@ 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);
+
+       ret = asymmetric_verify_common(key, pk, sig, siglen, data, datalen);
+
+       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


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