xref: /openbmc/linux/certs/Makefile (revision bc5aa3a0) 
1#
2# Makefile for the linux kernel signature checking certificates.
3#
4
5obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o
6
7ifeq ($(CONFIG_SYSTEM_TRUSTED_KEYRING),y)
8
9$(eval $(call config_filename,SYSTEM_TRUSTED_KEYS))
10
11# GCC doesn't include .incbin files in -MD generated dependencies (PR#66871)
12$(obj)/system_certificates.o: $(obj)/x509_certificate_list
13
14# Cope with signing_key.x509 existing in $(srctree) not $(objtree)
15AFLAGS_system_certificates.o := -I$(srctree)
16
17quiet_cmd_extract_certs  = EXTRACT_CERTS   $(patsubst "%",%,$(2))
18      cmd_extract_certs  = scripts/extract-cert $(2) $@ || ( rm $@; exit 1)
19
20targets += x509_certificate_list
21$(obj)/x509_certificate_list: scripts/extract-cert $(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(SYSTEM_TRUSTED_KEYS_FILENAME) FORCE
22	$(call if_changed,extract_certs,$(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_TRUSTED_KEYS))
23endif
24
25clean-files := x509_certificate_list .x509.list
26
27ifeq ($(CONFIG_MODULE_SIG),y)
28###############################################################################
29#
30# If module signing is requested, say by allyesconfig, but a key has not been
31# supplied, then one will need to be generated to make sure the build does not
32# fail and that the kernel may be used afterwards.
33#
34###############################################################################
35ifndef CONFIG_MODULE_SIG_HASH
36$(error Could not determine digest type to use from kernel config)
37endif
38
39redirect_openssl	= 2>&1
40quiet_redirect_openssl	= 2>&1
41silent_redirect_openssl = 2>/dev/null
42
43# We do it this way rather than having a boolean option for enabling an
44# external private key, because 'make randconfig' might enable such a
45# boolean option and we unfortunately can't make it depend on !RANDCONFIG.
46ifeq ($(CONFIG_MODULE_SIG_KEY),"certs/signing_key.pem")
47$(obj)/signing_key.pem: $(obj)/x509.genkey
48	@$(kecho) "###"
49	@$(kecho) "### Now generating an X.509 key pair to be used for signing modules."
50	@$(kecho) "###"
51	@$(kecho) "### If this takes a long time, you might wish to run rngd in the"
52	@$(kecho) "### background to keep the supply of entropy topped up.  It"
53	@$(kecho) "### needs to be run as root, and uses a hardware random"
54	@$(kecho) "### number generator if one is available."
55	@$(kecho) "###"
56	$(Q)openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
57		-batch -x509 -config $(obj)/x509.genkey \
58		-outform PEM -out $(obj)/signing_key.pem \
59		-keyout $(obj)/signing_key.pem \
60		$($(quiet)redirect_openssl)
61	@$(kecho) "###"
62	@$(kecho) "### Key pair generated."
63	@$(kecho) "###"
64
65$(obj)/x509.genkey:
66	@$(kecho) Generating X.509 key generation config
67	@echo  >$@ "[ req ]"
68	@echo >>$@ "default_bits = 4096"
69	@echo >>$@ "distinguished_name = req_distinguished_name"
70	@echo >>$@ "prompt = no"
71	@echo >>$@ "string_mask = utf8only"
72	@echo >>$@ "x509_extensions = myexts"
73	@echo >>$@
74	@echo >>$@ "[ req_distinguished_name ]"
75	@echo >>$@ "#O = Unspecified company"
76	@echo >>$@ "CN = Build time autogenerated kernel key"
77	@echo >>$@ "#emailAddress = unspecified.user@unspecified.company"
78	@echo >>$@
79	@echo >>$@ "[ myexts ]"
80	@echo >>$@ "basicConstraints=critical,CA:FALSE"
81	@echo >>$@ "keyUsage=digitalSignature"
82	@echo >>$@ "subjectKeyIdentifier=hash"
83	@echo >>$@ "authorityKeyIdentifier=keyid"
84endif
85
86$(eval $(call config_filename,MODULE_SIG_KEY))
87
88# If CONFIG_MODULE_SIG_KEY isn't a PKCS#11 URI, depend on it
89ifeq ($(patsubst pkcs11:%,%,$(firstword $(MODULE_SIG_KEY_FILENAME))),$(firstword $(MODULE_SIG_KEY_FILENAME)))
90X509_DEP := $(MODULE_SIG_KEY_SRCPREFIX)$(MODULE_SIG_KEY_FILENAME)
91endif
92
93# GCC PR#66871 again.
94$(obj)/system_certificates.o: $(obj)/signing_key.x509
95
96targets += signing_key.x509
97$(obj)/signing_key.x509: scripts/extract-cert $(X509_DEP) FORCE
98	$(call if_changed,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY))
99endif
100