Commit a4aed36e authored by Stefan Berger's avatar Stefan Berger Committed by Jarkko Sakkinen
Browse files

certs: Add support for using elliptic curve keys for signing modules 



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 should still
delete the signing key (rm certs/signing_key.*) when building an older
version of a kernel that only supports RSA keys. Unless kbuild automati-
cally detects and generates a new kernel module key, ECDSA-signed kernel
modules will fail signature verification.

Cc: David Howells <dhowells@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: default avatarStefan Berger <stefanb@linux.ibm.com>
Reviewed-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
Tested-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
parent ea35e0d5

certs/Kconfig

+26 −0
Original line number Diff line number Diff line
@@ -15,6 +15,32 @@ 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 generate. 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 && MODULES)

	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 && MODULES)

	help

	 Use an elliptic curve key (NIST P384) for module signing. Consider

	 using a strong hash like sha256 or sha384 for hashing modules.



	 Note: Remove all ECDSA signing keys, e.g. certs/signing_key.pem,

	 when falling back to building Linux 5.14 and older kernels.



endchoice



config SYSTEM_TRUSTED_KEYRING

	bool "Provide system-wide ring of trusted keys"

	depends on KEYS

certs/Makefile

+13 −0
Original line number Diff line number Diff line
@@ -66,9 +66,21 @@ ifeq ($(CONFIG_MODULE_SIG_KEY),"certs/signing_key.pem") 


ifeq ($(openssl_available),yes)

X509TEXT=$(shell openssl x509 -in "certs/signing_key.pem" -text 2>/dev/null)

endif



# Support user changing key type

ifdef CONFIG_MODULE_SIG_KEY_TYPE_ECDSA

keytype_openssl = -newkey ec -pkeyopt ec_paramgen_curve:secp384r1

ifeq ($(openssl_available),yes)

$(if $(findstring id-ecPublicKey,$(X509TEXT)),,$(shell rm -f "certs/signing_key.pem"))

endif

endif # CONFIG_MODULE_SIG_KEY_TYPE_ECDSA



ifdef CONFIG_MODULE_SIG_KEY_TYPE_RSA

ifeq ($(openssl_available),yes)

$(if $(findstring rsaEncryption,$(X509TEXT)),,$(shell rm -f "certs/signing_key.pem"))

endif

endif # CONFIG_MODULE_SIG_KEY_TYPE_RSA



$(obj)/signing_key.pem: $(obj)/x509.genkey

	@$(kecho) "###"
@@ -83,6 +95,7 @@ $(obj)/signing_key.pem: $(obj)/x509.genkey 
		-batch -x509 -config $(obj)/x509.genkey \

		-outform PEM -out $(obj)/signing_key.pem \

		-keyout $(obj)/signing_key.pem \

		$(keytype_openssl) \

		$($(quiet)redirect_openssl)

	@$(kecho) "###"

	@$(kecho) "### Key pair generated."

crypto/asymmetric_keys/pkcs7_parser.c

+8 −0
Original line number Diff line number Diff line
@@ -269,6 +269,14 @@ 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_sha1:

	case OID_id_ecdsa_with_sha224:

	case OID_id_ecdsa_with_sha256:

	case OID_id_ecdsa_with_sha384:

	case OID_id_ecdsa_with_sha512:

		ctx->sinfo->sig->pkey_algo = "ecdsa";

		ctx->sinfo->sig->encoding = "x962";

		break;

	default:

		printk("Unsupported pkey algo: %u\n", ctx->last_oid);

		return -ENOPKG;