x509: Separately calculate sha256 for blacklist

Calculate the SHA256 hash for blacklisting purposes independently of the
signature hash (which may be something other than SHA256).

This is necessary because when ML-DSA is used, no digest is calculated.

Note that this represents a change of behaviour in that the hash used for
the blacklist check would previously have been whatever digest was used
for, say, RSA-based signatures.  It may be that this is inadvisable.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
cc: Lukas Wunner <lukas@wunner.de>
cc: Ignat Korchagin <ignat@cloudflare.com>
cc: Stephan Mueller <smueller@chronox.de>
cc: Eric Biggers <ebiggers@kernel.org>
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: keyrings@vger.kernel.org
cc: linux-crypto@vger.kernel.org

diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
index 0688c222806b0160f4749951d14e16d59cfe4970..b7aeebdddb3601884378499680b50543619cd55f 100644 (file)
--- a/crypto/asymmetric_keys/x509_parser.h
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -9,12 +9,14 @@
 #include <linux/time.h>
 #include <crypto/public_key.h>
 #include <keys/asymmetric-type.h>
+#include <crypto/sha2.h>
 
 struct x509_certificate {
        struct x509_certificate *next;
        struct x509_certificate *signer;        /* Certificate that signed this one */
        struct public_key *pub;                 /* Public key details */
        struct public_key_signature *sig;       /* Signature parameters */
+       u8              sha256[SHA256_DIGEST_SIZE]; /* Hash for blacklist purposes */
        char            *issuer;                /* Name of certificate issuer */
        char            *subject;               /* Name of certificate subject */
        struct asymmetric_key_id *id;           /* Issuer + Serial number */

diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 12e3341e806b8db93803325a96a3821fd5d0a9f0..79cc7b7a0630b7e90e491b911fcae5b3daaa5719 100644 (file)
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -31,6 +31,19 @@ int x509_get_sig_params(struct x509_certificate *cert)
 
        pr_devel("==>%s()\n", __func__);
 
+       /* Calculate a SHA256 hash of the TBS and check it against the
+        * blacklist.
+        */
+       sha256(cert->tbs, cert->tbs_size, cert->sha256);
+       ret = is_hash_blacklisted(cert->sha256, sizeof(cert->sha256),
+                                 BLACKLIST_HASH_X509_TBS);
+       if (ret == -EKEYREJECTED) {
+               pr_err("Cert %*phN is blacklisted\n",
+                      (int)sizeof(cert->sha256), cert->sha256);
+               cert->blacklisted = true;
+               ret = 0;
+       }
+
        sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
        if (!sig->s)
                return -ENOMEM;
@@ -69,15 +82,6 @@ int x509_get_sig_params(struct x509_certificate *cert)
        if (ret < 0)
                goto error_2;
 
-       ret = is_hash_blacklisted(sig->digest, sig->digest_size,
-                                 BLACKLIST_HASH_X509_TBS);
-       if (ret == -EKEYREJECTED) {
-               pr_err("Cert %*phN is blacklisted\n",
-                      sig->digest_size, sig->digest);
-               cert->blacklisted = true;
-               ret = 0;
-       }
-
 error_2:
        kfree(desc);
 error: