Move certificate handling to its own directory

Move certificate handling out of the kernel/ directory and into a certs/
directory to get all the weird stuff in one place and move the generated
signing keys into this directory.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Reviewed-by: NDavid Woodhouse <David.Woodhouse@intel.com>

Documentation/module-signing.txt

@@ -92,13 +92,13 @@ This has a number of options available:
  (4) "File name or PKCS#11 URI of module signing key" (CONFIG_MODULE_SIG_KEY)
 
      Setting this option to something other than its default of
-     "signing_key.pem" will disable the autogeneration of signing keys and
-     allow the kernel modules to be signed with a key of your choosing.
-     The string provided should identify a file containing both a private
-     key and its corresponding X.509 certificate in PEM form, or — on
-     systems where the OpenSSL ENGINE_pkcs11 is functional — a PKCS#11 URI
-     as defined by RFC7512. In the latter case, the PKCS#11 URI should
-     reference both a certificate and a private key.
+     "certs/signing_key.pem" will disable the autogeneration of signing keys
+     and allow the kernel modules to be signed with a key of your choosing.
+     The string provided should identify a file containing both a private key
+     and its corresponding X.509 certificate in PEM form, or — on systems where
+     the OpenSSL ENGINE_pkcs11 is functional — a PKCS#11 URI as defined by
+     RFC7512. In the latter case, the PKCS#11 URI should reference both a
+     certificate and a private key.
 
      If the PEM file containing the private key is encrypted, or if the
      PKCS#11 token requries a PIN, this can be provided at build time by
@@ -130,12 +130,12 @@ Under normal conditions, when CONFIG_MODULE_SIG_KEY is unchanged from its
 default, the kernel build will automatically generate a new keypair using
 openssl if one does not exist in the file:
 
-	signing_key.pem
+	certs/signing_key.pem
 
 during the building of vmlinux (the public part of the key needs to be built
 into vmlinux) using parameters in the:
 
-	x509.genkey
+	certs/x509.genkey
 
 file (which is also generated if it does not already exist).
 

MAINTAINERS

@@ -2589,6 +2589,15 @@ S:	Supported
 F:	Documentation/filesystems/ceph.txt
 F:	fs/ceph/
 
+CERTIFICATE HANDLING:
+M:	David Howells <dhowells@redhat.com>
+M:	David Woodhouse <dwmw2@infradead.org>
+L:	keyrings@linux-nfs.org
+S:	Maintained
+F:	Documentation/module-signing.txt
+F:	certs/
+F:	scripts/extract-cert.c
+
 CERTIFIED WIRELESS USB (WUSB) SUBSYSTEM:
 L:	linux-usb@vger.kernel.org
 S:	Orphan

Makefile

@@ -871,7 +871,7 @@ INITRD_COMPRESS-$(CONFIG_RD_LZ4)   := lz4
 
 ifdef CONFIG_MODULE_SIG_ALL
 MODSECKEY = $(CONFIG_MODULE_SIG_KEY)
-MODPUBKEY = ./signing_key.x509
+MODPUBKEY = certs/signing_key.x509
 export MODPUBKEY
 mod_sign_cmd = scripts/sign-file $(CONFIG_MODULE_SIG_HASH) $(MODSECKEY) $(MODPUBKEY)
 else
@@ -881,7 +881,7 @@ export mod_sign_cmd
 
 
 ifeq ($(KBUILD_EXTMOD),)
-core-y		+= kernel/ mm/ fs/ ipc/ security/ crypto/ block/
+core-y		+= kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/
 
 vmlinux-dirs	:= $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
 		     $(core-y) $(core-m) $(drivers-y) $(drivers-m) \

certs/Kconfig

+menu "Certificates for signature checking"
+
+config MODULE_SIG_KEY
+	string "File name or PKCS#11 URI of module signing key"
+	default "certs/signing_key.pem"
+	depends on MODULE_SIG
+	help
+         Provide the file name of a private key/certificate in PEM format,
+         or a PKCS#11 URI according to RFC7512. The file should contain, or
+         the URI should identify, both the certificate and its corresponding
+         private key.
+
+         If this option is unchanged from its default "certs/signing_key.pem",
+         then the kernel will automatically generate the private key and
+         certificate as described in Documentation/module-signing.txt
+
+config SYSTEM_TRUSTED_KEYRING
+	bool "Provide system-wide ring of trusted keys"
+	depends on KEYS
+	help
+	  Provide a system keyring to which trusted keys can be added.  Keys in
+	  the keyring are considered to be trusted.  Keys may be added at will
+	  by the kernel from compiled-in data and from hardware key stores, but
+	  userspace may only add extra keys if those keys can be verified by
+	  keys already in the keyring.
+
+	  Keys in this keyring are used by module signature checking.
+
+config SYSTEM_TRUSTED_KEYS
+	string "Additional X.509 keys for default system keyring"
+	depends on SYSTEM_TRUSTED_KEYRING
+	help
+	  If set, this option should be the filename of a PEM-formatted file
+	  containing trusted X.509 certificates to be included in the default
+	  system keyring. Any certificate used for module signing is implicitly
+	  also trusted.
+
+	  NOTE: If you previously provided keys for the system keyring in the
+	  form of DER-encoded *.x509 files in the top-level build directory,
+	  those are no longer used. You will need to set this option instead.
+
+endmenu

certs/Makefile

+#
+# Makefile for the linux kernel signature checking certificates.
+#
+
+obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o
+
+###############################################################################
+#
+# When a Kconfig string contains a filename, it is suitable for
+# passing to shell commands. It is surrounded by double-quotes, and
+# any double-quotes or backslashes within it are escaped by
+# backslashes.
+#
+# This is no use for dependencies or $(wildcard). We need to strip the
+# surrounding quotes and the escaping from quotes and backslashes, and
+# we *do* need to escape any spaces in the string. So, for example:
+#
+# Usage: $(eval $(call config_filename,FOO))
+#
+# Defines FOO_FILENAME based on the contents of the CONFIG_FOO option,
+# transformed as described above to be suitable for use within the
+# makefile.
+#
+# Also, if the filename is a relative filename and exists in the source
+# tree but not the build tree, define FOO_SRCPREFIX as $(srctree)/ to
+# be prefixed to *both* command invocation and dependencies.
+#
+# Note: We also print the filenames in the quiet_cmd_foo text, and
+# perhaps ought to have a version specially escaped for that purpose.
+# But it's only cosmetic, and $(patsubst "%",%,$(CONFIG_FOO)) is good
+# enough.  It'll strip the quotes in the common case where there's no
+# space and it's a simple filename, and it'll retain the quotes when
+# there's a space. There are some esoteric cases in which it'll print
+# the wrong thing, but we don't really care. The actual dependencies
+# and commands *do* get it right, with various combinations of single
+# and double quotes, backslashes and spaces in the filenames.
+#
+###############################################################################
+#
+quote := $(firstword " ")
+space :=
+space +=
+space_escape := %%%SPACE%%%
+#
+define config_filename
+ifneq ($$(CONFIG_$(1)),"")
+$(1)_FILENAME := $$(subst \\,\,$$(subst \$$(quote),$$(quote),$$(subst $$(space_escape),\$$(space),$$(patsubst "%",%,$$(subst $$(space),$$(space_escape),$$(CONFIG_$(1)))))))
+ifneq ($$(patsubst /%,%,$$(firstword $$($(1)_FILENAME))),$$(firstword $$($(1)_FILENAME)))
+else
+ifeq ($$(wildcard $$($(1)_FILENAME)),)
+ifneq ($$(wildcard $$(srctree)/$$($(1)_FILENAME)),)
+$(1)_SRCPREFIX := $(srctree)/
+endif
+endif
+endif
+endif
+endef
+#
+###############################################################################
+
+ifeq ($(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: $(obj)/signing_key.x509
+
+$(obj)/signing_key.x509: scripts/extract-cert include/config/module/sig/key.h $(X509_DEP)
+	$(call cmd,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY))
+endif

kernel/system_certificates.S → certs/system_certificates.S

@@ -8,9 +8,9 @@
 VMLINUX_SYMBOL(system_certificate_list):
 __cert_list_start:
 #ifdef CONFIG_MODULE_SIG
-	.incbin "signing_key.x509"
+	.incbin "certs/signing_key.x509"
 #endif
-	.incbin "kernel/x509_certificate_list"
+	.incbin "certs/x509_certificate_list"
 __cert_list_end:
 
 	.align 8

crypto/Kconfig

@@ -1601,5 +1601,6 @@ config CRYPTO_HASH_INFO
 
 source "drivers/crypto/Kconfig"
 source crypto/asymmetric_keys/Kconfig
+source certs/Kconfig
 
 endif	# if CRYPTO

init/Kconfig

@@ -1740,31 +1740,6 @@ config MMAP_ALLOW_UNINITIALIZED
 
 	  See Documentation/nommu-mmap.txt for more information.
 
-config SYSTEM_TRUSTED_KEYRING
-	bool "Provide system-wide ring of trusted keys"
-	depends on KEYS
-	help
-	  Provide a system keyring to which trusted keys can be added.  Keys in
-	  the keyring are considered to be trusted.  Keys may be added at will
-	  by the kernel from compiled-in data and from hardware key stores, but
-	  userspace may only add extra keys if those keys can be verified by
-	  keys already in the keyring.
-
-	  Keys in this keyring are used by module signature checking.
-
-config SYSTEM_TRUSTED_KEYS
-	string "Additional X.509 keys for default system keyring"
-	depends on SYSTEM_TRUSTED_KEYRING
-	help
-	  If set, this option should be the filename of a PEM-formatted file
-	  containing trusted X.509 certificates to be included in the default
-	  system keyring. Any certificate used for module signing is implicitly
-	  also trusted.
-
-	  NOTE: If you previously provided keys for the system keyring in the
-	  form of DER-encoded *.x509 files in the top-level build directory,
-	  those are no longer used. You will need to set this option instead.
-
 config SYSTEM_DATA_VERIFICATION
 	def_bool n
 	select SYSTEM_TRUSTED_KEYRING
@@ -1965,20 +1940,6 @@ config MODULE_SIG_HASH
 	default "sha384" if MODULE_SIG_SHA384
 	default "sha512" if MODULE_SIG_SHA512
 
-config MODULE_SIG_KEY
-	string "File name or PKCS#11 URI of module signing key"
-	default "signing_key.pem"
-	depends on MODULE_SIG
-	help
-         Provide the file name of a private key/certificate in PEM format,
-         or a PKCS#11 URI according to RFC7512. The file should contain, or
-         the URI should identify, both the certificate and its corresponding
-         private key.
-
-         If this option is unchanged from its default "signing_key.pem",
-         then the kernel will automatically generate the private key and
-         certificate as described in Documentation/module-signing.txt
-
 config MODULE_COMPRESS
 	bool "Compress modules on installation"
 	depends on MODULES

kernel/Makefile

@@ -45,7 +45,6 @@ ifneq ($(CONFIG_SMP),y)
 obj-y += up.o
 endif
 obj-$(CONFIG_UID16) += uid16.o
-obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o
 obj-$(CONFIG_MODULES) += module.o
 obj-$(CONFIG_MODULE_SIG) += module_signing.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
@@ -111,145 +110,3 @@ $(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE
 targets += config_data.h
 $(obj)/config_data.h: $(obj)/config_data.gz FORCE
 	$(call filechk,ikconfiggz)
-
-###############################################################################
-#
-# When a Kconfig string contains a filename, it is suitable for
-# passing to shell commands. It is surrounded by double-quotes, and
-# any double-quotes or backslashes within it are escaped by
-# backslashes.
-#
-# This is no use for dependencies or $(wildcard). We need to strip the
-# surrounding quotes and the escaping from quotes and backslashes, and
-# we *do* need to escape any spaces in the string. So, for example:
-#
-# Usage: $(eval $(call config_filename,FOO))
-#
-# Defines FOO_FILENAME based on the contents of the CONFIG_FOO option,
-# transformed as described above to be suitable for use within the
-# makefile.
-#
-# Also, if the filename is a relative filename and exists in the source
-# tree but not the build tree, define FOO_SRCPREFIX as $(srctree)/ to
-# be prefixed to *both* command invocation and dependencies.
-#
-# Note: We also print the filenames in the quiet_cmd_foo text, and
-# perhaps ought to have a version specially escaped for that purpose.
-# But it's only cosmetic, and $(patsubst "%",%,$(CONFIG_FOO)) is good
-# enough.  It'll strip the quotes in the common case where there's no
-# space and it's a simple filename, and it'll retain the quotes when
-# there's a space. There are some esoteric cases in which it'll print
-# the wrong thing, but we don't really care. The actual dependencies
-# and commands *do* get it right, with various combinations of single
-# and double quotes, backslashes and spaces in the filenames.
-#
-###############################################################################
-#
-quote := $(firstword " ")
-space :=
-space +=
-space_escape := %%%SPACE%%%
-#
-define config_filename
-ifneq ($$(CONFIG_$(1)),"")
-$(1)_FILENAME := $$(subst \\,\,$$(subst \$$(quote),$$(quote),$$(subst $$(space_escape),\$$(space),$$(patsubst "%",%,$$(subst $$(space),$$(space_escape),$$(CONFIG_$(1)))))))
-ifneq ($$(patsubst /%,%,$$(firstword $$($(1)_FILENAME))),$$(firstword $$($(1)_FILENAME)))
-else
-ifeq ($$(wildcard $$($(1)_FILENAME)),)
-ifneq ($$(wildcard $$(srctree)/$$($(1)_FILENAME)),)
-$(1)_SRCPREFIX := $(srctree)/
-endif
-endif
-endif
-endif
-endef
-#
-###############################################################################
-
-ifeq ($(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),"signing_key.pem")
-signing_key.pem: 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 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
-		-batch -x509 -config x509.genkey \
-		-outform PEM -out signing_key.pem \
-		-keyout signing_key.pem 2>&1
-	@echo "###"
-	@echo "### Key pair generated."
-	@echo "###"
-
-x509.genkey:
-	@echo Generating X.509 key generation config
-	@echo  >x509.genkey "[ req ]"
-	@echo >>x509.genkey "default_bits = 4096"
-	@echo >>x509.genkey "distinguished_name = req_distinguished_name"
-	@echo >>x509.genkey "prompt = no"
-	@echo >>x509.genkey "string_mask = utf8only"
-	@echo >>x509.genkey "x509_extensions = myexts"
-	@echo >>x509.genkey
-	@echo >>x509.genkey "[ req_distinguished_name ]"
-	@echo >>x509.genkey "#O = Unspecified company"
-	@echo >>x509.genkey "CN = Build time autogenerated kernel key"
-	@echo >>x509.genkey "#emailAddress = unspecified.user@unspecified.company"
-	@echo >>x509.genkey
-	@echo >>x509.genkey "[ myexts ]"
-	@echo >>x509.genkey "basicConstraints=critical,CA:FALSE"
-	@echo >>x509.genkey "keyUsage=digitalSignature"
-	@echo >>x509.genkey "subjectKeyIdentifier=hash"
-	@echo >>x509.genkey "authorityKeyIdentifier=keyid"
-endif
-
-$(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: signing_key.x509
-
-signing_key.x509: scripts/extract-cert include/config/module/sig/key.h $(X509_DEP)
-	$(call cmd,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY))
-endif