1 files changed, 94 insertions, 0 deletions

diff --git a/certs/Makefile b/certs/Makefile
new file mode 100644
index 000000000000..28ac694dd11a
--- /dev/null
+++ b/certs/Makefile
@@ -0,0 +1,94 @@
+#
+# Makefile for the linux kernel signature checking certificates.
+#
+
+obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o
+
+ifeq ($(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) $@ || ( rm $@; exit 1)
+
+targets += x509_certificate_list
+$(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)$(CONFIG_SYSTEM_TRUSTED_KEYS))
+endif
+
+clean-files := x509_certificate_list .x509.list
+
+ifeq ($(CONFIG_MODULE_SIG),y)
+###############################################################################
+#
+# 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
+$(error Could not determine digest type to use from kernel config)
+endif
+
+# We do it this way rather than having a boolean option for enabling an
+# external private key, because 'make randconfig' might enable such a
+# boolean option and we unfortunately can't make it depend on !RANDCONFIG.
+ifeq ($(CONFIG_MODULE_SIG_KEY),"certs/signing_key.pem")
+$(obj)/signing_key.pem: $(obj)/x509.genkey
+        @echo "###"
+        @echo "### Now generating an X.509 key pair to be used for signing modules."
+        @echo "###"
+        @echo "### If this takes a long time, you might wish to run rngd in the"
+        @echo "### background to keep the supply of entropy topped up.  It"
+        @echo "### needs to be run as root, and uses a hardware random"
+        @echo "### number generator if one is available."
+        @echo "###"
+        openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
+                -batch -x509 -config $(obj)/x509.genkey \
+                -outform PEM -out $(obj)/signing_key.pem \
+                -keyout $(obj)/signing_key.pem 2>&1
+        @echo "###"
+        @echo "### Key pair generated."
+        @echo "###"
+
+$(obj)/x509.genkey:
+        @echo 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 >>$@ "authorityKeyIdentifier=keyid"
+endif
+
+$(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