Allow the rejection of authenticatedAttributes in PKCS#7 (signedAttrs in
CMS) to be waived in the kernel config for ML-DSA when used for module
signing. This reflects the issue that openssl < 4.0 cannot do this and
openssl-4 has not yet been released.
This does not permit RSA, ECDSA or ECRDSA to be so waived (behaviour
unchanged).
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Lukas Wunner <lukas@wunner.de>
cc: Ignat Korchagin <ignat@cloudflare.com>
cc: Jarkko Sakkinen <jarkko@kernel.org>
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
---
crypto/asymmetric_keys/Kconfig | 11 +++++++++++
crypto/asymmetric_keys/pkcs7_parser.c | 8 ++++++++
crypto/asymmetric_keys/pkcs7_parser.h | 3 +++
crypto/asymmetric_keys/pkcs7_verify.c | 6 ++++++
4 files changed, 28 insertions(+)
diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index e1345b8f39f1..1dae2232fe9a 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -53,6 +53,17 @@ config PKCS7_MESSAGE_PARSER
This option provides support for parsing PKCS#7 format messages for
signature data and provides the ability to verify the signature.
+config PKCS7_WAIVE_AUTHATTRS_REJECTION_FOR_MLDSA
+ bool "Waive rejection of authenticatedAttributes for ML-DSA"
+ depends on PKCS7_MESSAGE_PARSER
+ depends on CRYPTO_MLDSA
+ help
+ Due to use of CMS_NOATTR with ML-DSA not being supported in
+ OpenSSL < 4.0 (and thus any released version), enabling this
+ allows authenticatedAttributes to be used with ML-DSA for
+ module signing. Use of authenticatedAttributes in this
+ context is normally rejected.
+
config PKCS7_TEST_KEY
tristate "PKCS#7 testing key type"
depends on SYSTEM_DATA_VERIFICATION
diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
index 594a8f1d9dfb..db1c90ca6fc1 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.c
+++ b/crypto/asymmetric_keys/pkcs7_parser.c
@@ -92,9 +92,17 @@ static int pkcs7_check_authattrs(struct pkcs7_message *msg)
if (!sinfo)
goto inconsistent;
+#ifdef CONFIG_PKCS7_WAIVE_AUTHATTRS_REJECTION_FOR_MLDSA
+ msg->authattrs_rej_waivable = true;
+#endif
+
if (sinfo->authattrs) {
want = true;
msg->have_authattrs = true;
+#ifdef CONFIG_PKCS7_WAIVE_AUTHATTRS_REJECTION_FOR_MLDSA
+ if (strncmp(sinfo->sig->pkey_algo, "mldsa", 5) != 0)
+ msg->authattrs_rej_waivable = false;
+#endif
} else if (sinfo->sig->algo_takes_data) {
sinfo->sig->hash_algo = "none";
}
diff --git a/crypto/asymmetric_keys/pkcs7_parser.h b/crypto/asymmetric_keys/pkcs7_parser.h
index e17f7ce4fb43..6ef9f335bb17 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.h
+++ b/crypto/asymmetric_keys/pkcs7_parser.h
@@ -55,6 +55,9 @@ struct pkcs7_message {
struct pkcs7_signed_info *signed_infos;
u8 version; /* Version of cert (1 -> PKCS#7 or CMS; 3 -> CMS) */
bool have_authattrs; /* T if have authattrs */
+#ifdef CONFIG_PKCS7_WAIVE_AUTHATTRS_REJECTION_FOR_MLDSA
+ bool authattrs_rej_waivable; /* T if authatts rejection can be waived */
+#endif
/* Content Data (or NULL) */
enum OID data_type; /* Type of Data */
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index 06abb9838f95..519eecfe6778 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -425,6 +425,12 @@ int pkcs7_verify(struct pkcs7_message *pkcs7,
return -EKEYREJECTED;
}
if (pkcs7->have_authattrs) {
+#ifdef CONFIG_PKCS7_WAIVE_AUTHATTRS_REJECTION_FOR_MLDSA
+ if (pkcs7->authattrs_rej_waivable) {
+ pr_warn("Waived invalid module sig (has authattrs)\n");
+ break;
+ }
+#endif
pr_warn("Invalid module sig (has authattrs)\n");
return -EKEYREJECTED;
}