linux-stable/certs/Makefile
Stefan Berger a4aed36ed5 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: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
2021-08-23 19:55:42 +03:00

152 lines
5.5 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
#
# Makefile for the linux kernel signature checking certificates.
#
obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o common.o
obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist.o common.o
obj-$(CONFIG_SYSTEM_REVOCATION_LIST) += revocation_certificates.o
ifneq ($(CONFIG_SYSTEM_BLACKLIST_HASH_LIST),"")
obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_hashes.o
else
obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_nohashes.o
endif
ifeq ($(CONFIG_SYSTEM_TRUSTED_KEYRING),y)
$(eval $(call config_filename,SYSTEM_TRUSTED_KEYS))
# GCC doesn't include .incbin files in -MD generated dependencies (PR#66871)
$(obj)/system_certificates.o: $(obj)/x509_certificate_list
# Cope with signing_key.x509 existing in $(srctree) not $(objtree)
AFLAGS_system_certificates.o := -I$(srctree)
quiet_cmd_extract_certs = EXTRACT_CERTS $(patsubst "%",%,$(2))
cmd_extract_certs = scripts/extract-cert $(2) $@
targets += x509_certificate_list
$(obj)/x509_certificate_list: scripts/extract-cert $(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(SYSTEM_TRUSTED_KEYS_FILENAME) FORCE
$(call if_changed,extract_certs,$(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_TRUSTED_KEYS))
endif # CONFIG_SYSTEM_TRUSTED_KEYRING
clean-files := x509_certificate_list .x509.list x509_revocation_list
ifeq ($(CONFIG_MODULE_SIG),y)
SIGN_KEY = y
endif
ifeq ($(CONFIG_IMA_APPRAISE_MODSIG),y)
ifeq ($(CONFIG_MODULES),y)
SIGN_KEY = y
endif
endif
ifdef SIGN_KEY
###############################################################################
#
# If module signing is requested, say by allyesconfig, but a key has not been
# supplied, then one will need to be generated to make sure the build does not
# fail and that the kernel may be used afterwards.
#
###############################################################################
ifndef CONFIG_MODULE_SIG_HASH
$(error Could not determine digest type to use from kernel config)
endif
redirect_openssl = 2>&1
quiet_redirect_openssl = 2>&1
silent_redirect_openssl = 2>/dev/null
openssl_available = $(shell openssl help 2>/dev/null && echo yes)
# We do it this way rather than having a boolean option for enabling an
# external private key, because 'make randconfig' might enable such a
# boolean option and we unfortunately can't make it depend on !RANDCONFIG.
ifeq ($(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) "###"
@$(kecho) "### Now generating an X.509 key pair to be used for signing modules."
@$(kecho) "###"
@$(kecho) "### If this takes a long time, you might wish to run rngd in the"
@$(kecho) "### background to keep the supply of entropy topped up. It"
@$(kecho) "### needs to be run as root, and uses a hardware random"
@$(kecho) "### number generator if one is available."
@$(kecho) "###"
$(Q)openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
-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."
@$(kecho) "###"
$(obj)/x509.genkey:
@$(kecho) Generating X.509 key generation config
@echo >$@ "[ req ]"
@echo >>$@ "default_bits = 4096"
@echo >>$@ "distinguished_name = req_distinguished_name"
@echo >>$@ "prompt = no"
@echo >>$@ "string_mask = utf8only"
@echo >>$@ "x509_extensions = myexts"
@echo >>$@
@echo >>$@ "[ req_distinguished_name ]"
@echo >>$@ "#O = Unspecified company"
@echo >>$@ "CN = Build time autogenerated kernel key"
@echo >>$@ "#emailAddress = unspecified.user@unspecified.company"
@echo >>$@
@echo >>$@ "[ myexts ]"
@echo >>$@ "basicConstraints=critical,CA:FALSE"
@echo >>$@ "keyUsage=digitalSignature"
@echo >>$@ "subjectKeyIdentifier=hash"
@echo >>$@ "authorityKeyIdentifier=keyid"
endif # CONFIG_MODULE_SIG_KEY
$(eval $(call config_filename,MODULE_SIG_KEY))
# If CONFIG_MODULE_SIG_KEY isn't a PKCS#11 URI, depend on it
ifeq ($(patsubst pkcs11:%,%,$(firstword $(MODULE_SIG_KEY_FILENAME))),$(firstword $(MODULE_SIG_KEY_FILENAME)))
X509_DEP := $(MODULE_SIG_KEY_SRCPREFIX)$(MODULE_SIG_KEY_FILENAME)
endif
# GCC PR#66871 again.
$(obj)/system_certificates.o: $(obj)/signing_key.x509
targets += signing_key.x509
$(obj)/signing_key.x509: scripts/extract-cert $(X509_DEP) FORCE
$(call if_changed,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY))
endif # CONFIG_MODULE_SIG
ifeq ($(CONFIG_SYSTEM_REVOCATION_LIST),y)
$(eval $(call config_filename,SYSTEM_REVOCATION_KEYS))
$(obj)/revocation_certificates.o: $(obj)/x509_revocation_list
quiet_cmd_extract_certs = EXTRACT_CERTS $(patsubst "%",%,$(2))
cmd_extract_certs = scripts/extract-cert $(2) $@
targets += x509_revocation_list
$(obj)/x509_revocation_list: scripts/extract-cert $(SYSTEM_REVOCATION_KEYS_SRCPREFIX)$(SYSTEM_REVOCATION_KEYS_FILENAME) FORCE
$(call if_changed,extract_certs,$(SYSTEM_REVOCATION_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_REVOCATION_KEYS))
endif