Patch "KEYS: asymmetric: enforce SM2 signature use pkey algo" has been added to the 5.18-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    KEYS: asymmetric: enforce SM2 signature use pkey algo

to the 5.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     keys-asymmetric-enforce-sm2-signature-use-pkey-algo.patch
and it can be found in the queue-5.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7537225de80672a829ff983a94b62557441b5bf3
Author: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
Date:   Tue Jun 28 11:37:20 2022 +0800

    KEYS: asymmetric: enforce SM2 signature use pkey algo
    
    [ Upstream commit 0815291a8fd66cdcf7db1445d4d99b0d16065829 ]
    
    The signature verification of SM2 needs to add the Za value and
    recalculate sig->digest, which requires the detection of the pkey_algo
    in public_key_verify_signature(). As Eric Biggers said, the pkey_algo
    field in sig is attacker-controlled and should be use pkey->pkey_algo
    instead of sig->pkey_algo, and secondly, if sig->pkey_algo is NULL, it
    will also cause signature verification failure.
    
    The software_key_determine_akcipher() already forces the algorithms
    are matched, so the SM3 algorithm is enforced in the SM2 signature,
    although this has been checked, we still avoid using any algorithm
    information in the signature as input.
    
    Fixes: 215525639631 ("X.509: support OSCCA SM2-with-SM3 certificate verification")
    Reported-by: Eric Biggers <ebiggers@xxxxxxxxxx>
    Cc: stable@xxxxxxxxxxxxxxx # v5.10+
    Signed-off-by: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
    Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
    Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index 7c9e6be35c30..2f8352e88860 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -304,6 +304,10 @@ static int cert_sig_digest_update(const struct public_key_signature *sig,
 
 	BUG_ON(!sig->data);
 
+	/* SM2 signatures always use the SM3 hash algorithm */
+	if (!sig->hash_algo || strcmp(sig->hash_algo, "sm3") != 0)
+		return -EINVAL;
+
 	ret = sm2_compute_z_digest(tfm_pkey, SM2_DEFAULT_USERID,
 					SM2_DEFAULT_USERID_LEN, dgst);
 	if (ret)
@@ -414,8 +418,7 @@ int public_key_verify_signature(const struct public_key *pkey,
 	if (ret)
 		goto error_free_key;
 
-	if (sig->pkey_algo && strcmp(sig->pkey_algo, "sm2") == 0 &&
-	    sig->data_size) {
+	if (strcmp(pkey->pkey_algo, "sm2") == 0 && sig->data_size) {
 		ret = cert_sig_digest_update(sig, tfm);
 		if (ret)
 			goto error_free_key;