Re: [PATCH v16 7/7] pkcs7: Allow authenticatedAttributes for ML-DSA

[Jarkko Sakkinen <jarkko@kernel.org>]

On Mon, Feb 02, 2026 at 05:02:12PM +0000, David Howells wrote:
> 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;
>  		}
> 

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko