[PATCH RFC v6] integrity: support EC-RDSA signatures for asymmetric_verify

[Vitaly Chikunov]

Allow to use EC-RDSA signatures for IMA by determining signature type by
the hash algorithm name. This works good for EC-RDSA since Streebog and
EC-RDSA should always be used together.

Cc: Mimi Zohar <zohar@xxxxxxxxxxxxx>
Cc: Dmitry Kasatkin <dmitry.kasatkin@xxxxxxxxx>
Cc: linux-integrity@xxxxxxxxxxxxxxx
Signed-off-by: Vitaly Chikunov <vt@xxxxxxxxxxxx>
---
Changes since v5:

- This should go over "[PATCH v5 00/10] crypto: add EC-RDSA (GOST 34.10)
  algorithm" instead of "[PATCH v5 10/10] integrity: support EC-RDSA signatures
  for asymmetric_verify."

- Comparison of hash algo by enum id instead of text name, as suggested by
  Thiago Jung Bauermann and Mimi Zohar.

 security/integrity/digsig_asymmetric.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
index d775e03fbbcc..99080871eb9f 100644
--- a/security/integrity/digsig_asymmetric.c
+++ b/security/integrity/digsig_asymmetric.c
@@ -104,9 +104,16 @@ int asymmetric_verify(struct key *keyring, const char *sig,
 
 	memset(&pks, 0, sizeof(pks));
 
-	pks.pkey_algo = "rsa";
 	pks.hash_algo = hash_algo_name[hdr->hash_algo];
-	pks.encoding = "pkcs1";
+	if (hdr->hash_algo == HASH_ALGO_STREEBOG_256 ||
+	    hdr->hash_algo == HASH_ALGO_STREEBOG_512) {
+		/* EC-RDSA and Streebog should go together. */
+		pks.pkey_algo = "ecrdsa";
+		pks.encoding = "raw";
+	} else {
+		pks.pkey_algo = "rsa";
+		pks.encoding = "pkcs1";
+	}
 	pks.digest = (u8 *)data;
 	pks.digest_size = datalen;
 	pks.s = hdr->sig;
-- 
2.11.0