From: Stefan Berger <stef...@linux.ibm.com> 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 <stef...@linux.ibm.com> Reviewed-by: Mimi Zohar <zo...@linux.ibm.com> --- 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
