On Fri, Mar 05, 2021 at 03:59:56PM -0500, Stefan Berger wrote:
> From: Stefan Berger
>
> Add support for using elliptic curve keys for signing modules. It uses
> a NIST P384 (secp384r1) key if the user chooses an elliptic curve key
> and will have ECDSA support built into the kernel.
>
> Note: A developer choosing an ECDSA key for signing modules has to
> manually delete the signing key (rm certs/signing_key.*) when falling
> back to building an older version of a kernel that only supports RSA
> keys since otherwise ECDSA-signed modules will not be usable when that
> older kernel runs and the ECDSA key was still used for signing modules.
>
> Signed-off-by: Stefan Berger
> Reviewed-by: Mimi Zohar
Acked-by: Jarkko Sakkinen
/Jarkko
> ---
>
> v8->v9:
> - Automatically select CONFIG_ECDSA for built-in ECDSA support
> - Added help documentation
>
> This patch builds on top Nayna's series for 'kernel build support for
> loading the kernel module signing key'.
> - https://lkml.org/lkml/2021/2/18/856
> ---
> certs/Kconfig | 22 ++
> certs/Makefile| 14 ++
> crypto/asymmetric_keys/pkcs7_parser.c | 4
> 3 files changed, 40 insertions(+)
>
> diff --git a/certs/Kconfig b/certs/Kconfig
> index 48675ad319db..919db43ce80b 100644
> --- a/certs/Kconfig
> +++ b/certs/Kconfig
> @@ -15,6 +15,28 @@ config MODULE_SIG_KEY
> then the kernel will automatically generate the private key and
> certificate as described in
> Documentation/admin-guide/module-signing.rst
>
> +choice
> + prompt "Type of module signing key to be generated"
> + default MODULE_SIG_KEY_TYPE_RSA
> + help
> + The type of module signing key type to generated. This option
> + does not apply if a #PKCS11 URI is used.
> +
> +config MODULE_SIG_KEY_TYPE_RSA
> + bool "RSA"
> + depends on MODULE_SIG || IMA_APPRAISE_MODSIG
> + help
> + Use an RSA key for module signing.
> +
> +config MODULE_SIG_KEY_TYPE_ECDSA
> + bool "ECDSA"
> + select CRYPTO_ECDSA
> + depends on MODULE_SIG || IMA_APPRAISE_MODSIG
> + help
> + Use an elliptic curve key (NIST P384) for module signing.
> +
> +endchoice
> +
> config SYSTEM_TRUSTED_KEYRING
> bool "Provide system-wide ring of trusted keys"
> depends on KEYS
> diff --git a/certs/Makefile b/certs/Makefile
> index 3fe6b73786fa..c487d7021c54 100644
> --- a/certs/Makefile
> +++ b/certs/Makefile
> @@ -69,6 +69,18 @@ else
> SIGNER = -signkey $(obj)/signing_key.key
> endif # CONFIG_IMA_APPRAISE_MODSIG
>
> +X509TEXT=$(shell openssl x509 -in $(CONFIG_MODULE_SIG_KEY) -text)
> +
> +# Support user changing key type
> +ifdef CONFIG_MODULE_SIG_KEY_TYPE_ECDSA
> +keytype_openssl = -newkey ec -pkeyopt ec_paramgen_curve:secp384r1
> +$(if $(findstring ecdsa-with-,$(X509TEXT)),,$(shell rm -f
> $(CONFIG_MODULE_SIG_KEY)))
> +endif
> +
> +ifdef CONFIG_MODULE_SIG_KEY_TYPE_RSA
> +$(if $(findstring rsaEncryption,$(X509TEXT)),,$(shell rm -f
> $(CONFIG_MODULE_SIG_KEY)))
> +endif
> +
> $(obj)/signing_key.pem: $(obj)/x509.genkey
> @$(kecho) "###"
> @$(kecho) "### Now generating an X.509 key pair to be used for signing
> modules."
> @@ -86,12 +98,14 @@ ifeq ($(CONFIG_IMA_APPRAISE_MODSIG),y)
> -batch -x509 -config $(obj)/x509.genkey \
> -outform PEM -out $(CA_KEY) \
> -keyout $(CA_KEY) -extensions ca_ext \
> + $(keytype_openssl) \
> $($(quiet)redirect_openssl)
> endif # CONFIG_IMA_APPRAISE_MODSIG
> $(Q)openssl req -new -nodes -utf8 \
> -batch -config $(obj)/x509.genkey \
> -outform PEM -out $(obj)/signing_key.csr \
> -keyout $(obj)/signing_key.key -extensions myexts \
> + $(keytype_openssl) \
> $($(quiet)redirect_openssl)
> $(Q)openssl x509 -req -days 36500 -in $(obj)/signing_key.csr \
> -outform PEM -out $(obj)/signing_key.crt $(SIGNER) \
> diff --git a/crypto/asymmetric_keys/pkcs7_parser.c
> b/crypto/asymmetric_keys/pkcs7_parser.c
> index 967329e0a07b..2546ec6a0505 100644
> --- a/crypto/asymmetric_keys/pkcs7_parser.c
> +++ b/crypto/asymmetric_keys/pkcs7_parser.c
> @@ -269,6 +269,10 @@ int pkcs7_sig_note_pkey_algo(void *context, size_t
> hdrlen,
> ctx->sinfo->sig->pkey_algo = "rsa";
> ctx->sinfo->sig->encoding = "pkcs1";
> break;
> + case OID_id_ecdsa_with_sha256:
> + ctx->sinfo->sig->pkey_algo = "ecdsa";
> + ctx->sinfo->sig->encoding = "x962";
> + break;
> default:
> printk("Unsupported pkey algo: %u\n", ctx->last_oid);
> return -ENOPKG;
> --
> 2.29.2
>
>
