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x509: Separately calculate sha256 for blacklist

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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
This commit is contained in:
David Howells 2026-01-21 13:33:37 +00:00
parent d3b6dd90e2
commit 2c62068ac8
2 changed files with 15 additions and 9 deletions
Download patch file Download diff file Expand all files Collapse all files

2
crypto/asymmetric_keys/x509_parser.h
View file

@ -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 */

22
crypto/asymmetric_keys/x509_public_key.c
View file

@ -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: