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: David Howells <dhowells@redhat.com> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>tirimbino
David Howells
10 years ago
committed by
David Woodhouse
parent
0e38c35815
commit
cfc411e7ff
@ -0,0 +1,42 @@ |
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menu "Certificates for signature checking" |
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config MODULE_SIG_KEY |
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string "File name or PKCS#11 URI of module signing key" |
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default "certs/signing_key.pem" |
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depends on MODULE_SIG |
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help |
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Provide the file name of a private key/certificate in PEM format, |
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or a PKCS#11 URI according to RFC7512. The file should contain, or |
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the URI should identify, both the certificate and its corresponding |
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private key. |
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If this option is unchanged from its default "certs/signing_key.pem", |
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then the kernel will automatically generate the private key and |
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certificate as described in Documentation/module-signing.txt |
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config SYSTEM_TRUSTED_KEYRING |
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bool "Provide system-wide ring of trusted keys" |
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depends on KEYS |
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help |
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Provide a system keyring to which trusted keys can be added. Keys in |
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the keyring are considered to be trusted. Keys may be added at will |
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by the kernel from compiled-in data and from hardware key stores, but |
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userspace may only add extra keys if those keys can be verified by |
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keys already in the keyring. |
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Keys in this keyring are used by module signature checking. |
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config SYSTEM_TRUSTED_KEYS |
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string "Additional X.509 keys for default system keyring" |
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depends on SYSTEM_TRUSTED_KEYRING |
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help |
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If set, this option should be the filename of a PEM-formatted file |
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containing trusted X.509 certificates to be included in the default |
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system keyring. Any certificate used for module signing is implicitly |
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also trusted. |
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NOTE: If you previously provided keys for the system keyring in the |
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form of DER-encoded *.x509 files in the top-level build directory, |
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those are no longer used. You will need to set this option instead. |
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endmenu |
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@ -0,0 +1,147 @@ |
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#
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# Makefile for the linux kernel signature checking certificates.
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#
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obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o
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###############################################################################
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#
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# When a Kconfig string contains a filename, it is suitable for
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# passing to shell commands. It is surrounded by double-quotes, and
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# any double-quotes or backslashes within it are escaped by
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# backslashes.
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#
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# This is no use for dependencies or $(wildcard). We need to strip the
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# surrounding quotes and the escaping from quotes and backslashes, and
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# we *do* need to escape any spaces in the string. So, for example:
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#
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# Usage: $(eval $(call config_filename,FOO))
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#
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# Defines FOO_FILENAME based on the contents of the CONFIG_FOO option,
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# transformed as described above to be suitable for use within the
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# makefile.
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#
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# Also, if the filename is a relative filename and exists in the source
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# tree but not the build tree, define FOO_SRCPREFIX as $(srctree)/ to
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# be prefixed to *both* command invocation and dependencies.
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#
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# Note: We also print the filenames in the quiet_cmd_foo text, and
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# perhaps ought to have a version specially escaped for that purpose.
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# But it's only cosmetic, and $(patsubst "%",%,$(CONFIG_FOO)) is good
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# enough. It'll strip the quotes in the common case where there's no
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# space and it's a simple filename, and it'll retain the quotes when
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# there's a space. There are some esoteric cases in which it'll print
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# the wrong thing, but we don't really care. The actual dependencies
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# and commands *do* get it right, with various combinations of single
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# and double quotes, backslashes and spaces in the filenames.
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#
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###############################################################################
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#
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quote := $(firstword " ")
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space :=
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space +=
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space_escape := %%%SPACE%%%
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#
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define config_filename |
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ifneq ($$(CONFIG_$(1)),"") |
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$(1)_FILENAME := $$(subst \\,\,$$(subst \$$(quote),$$(quote),$$(subst $$(space_escape),\$$(space),$$(patsubst "%",%,$$(subst $$(space),$$(space_escape),$$(CONFIG_$(1)))))))
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ifneq ($$(patsubst /%,%,$$(firstword $$($(1)_FILENAME))),$$(firstword $$($(1)_FILENAME))) |
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else |
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ifeq ($$(wildcard $$($(1)_FILENAME)),) |
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ifneq ($$(wildcard $$(srctree)/$$($(1)_FILENAME)),) |
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$(1)_SRCPREFIX := $(srctree)/
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endif |
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endif |
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endif |
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endif |
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endef |
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#
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###############################################################################
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ifeq ($(CONFIG_SYSTEM_TRUSTED_KEYRING),y) |
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$(eval $(call config_filename,SYSTEM_TRUSTED_KEYS)) |
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# GCC doesn't include .incbin files in -MD generated dependencies (PR#66871)
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$(obj)/system_certificates.o: $(obj)/x509_certificate_list |
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# Cope with signing_key.x509 existing in $(srctree) not $(objtree)
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AFLAGS_system_certificates.o := -I$(srctree)
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quiet_cmd_extract_certs = EXTRACT_CERTS $(patsubst "%",%,$(2))
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cmd_extract_certs = scripts/extract-cert $(2) $@ || ( rm $@; exit 1)
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targets += x509_certificate_list
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$(obj)/x509_certificate_list: scripts/extract-cert $(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(SYSTEM_TRUSTED_KEYS_FILENAME) FORCE |
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$(call if_changed,extract_certs,$(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_TRUSTED_KEYS))
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endif |
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clean-files := x509_certificate_list .x509.list
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ifeq ($(CONFIG_MODULE_SIG),y) |
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###############################################################################
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#
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# If module signing is requested, say by allyesconfig, but a key has not been
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# supplied, then one will need to be generated to make sure the build does not
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# fail and that the kernel may be used afterwards.
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#
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###############################################################################
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ifndef CONFIG_MODULE_SIG_HASH |
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$(error Could not determine digest type to use from kernel config) |
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endif |
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# We do it this way rather than having a boolean option for enabling an
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# external private key, because 'make randconfig' might enable such a
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# boolean option and we unfortunately can't make it depend on !RANDCONFIG.
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ifeq ($(CONFIG_MODULE_SIG_KEY),"certs/signing_key.pem") |
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$(obj)/signing_key.pem: $(obj)/x509.genkey |
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@echo "###"
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@echo "### Now generating an X.509 key pair to be used for signing modules."
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@echo "###"
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@echo "### If this takes a long time, you might wish to run rngd in the"
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@echo "### background to keep the supply of entropy topped up. It"
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@echo "### needs to be run as root, and uses a hardware random"
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@echo "### number generator if one is available."
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@echo "###"
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openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
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-batch -x509 -config $(obj)/x509.genkey \
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-outform PEM -out $(obj)/signing_key.pem \
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-keyout $(obj)/signing_key.pem 2>&1
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@echo "###"
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@echo "### Key pair generated."
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@echo "###"
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$(obj)/x509.genkey: |
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@echo Generating X.509 key generation config
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@echo >$@ "[ req ]"
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@echo >>$@ "default_bits = 4096"
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@echo >>$@ "distinguished_name = req_distinguished_name"
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@echo >>$@ "prompt = no"
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@echo >>$@ "string_mask = utf8only"
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@echo >>$@ "x509_extensions = myexts"
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@echo >>$@
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@echo >>$@ "[ req_distinguished_name ]"
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@echo >>$@ "#O = Unspecified company"
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@echo >>$@ "CN = Build time autogenerated kernel key"
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@echo >>$@ "#emailAddress = unspecified.user@unspecified.company"
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@echo >>$@
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@echo >>$@ "[ myexts ]"
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@echo >>$@ "basicConstraints=critical,CA:FALSE"
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@echo >>$@ "keyUsage=digitalSignature"
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@echo >>$@ "subjectKeyIdentifier=hash"
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@echo >>$@ "authorityKeyIdentifier=keyid"
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endif |
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$(eval $(call config_filename,MODULE_SIG_KEY)) |
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# If CONFIG_MODULE_SIG_KEY isn't a PKCS#11 URI, depend on it
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ifeq ($(patsubst pkcs11:%,%,$(firstword $(MODULE_SIG_KEY_FILENAME))),$(firstword $(MODULE_SIG_KEY_FILENAME))) |
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X509_DEP := $(MODULE_SIG_KEY_SRCPREFIX)$(MODULE_SIG_KEY_FILENAME)
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endif |
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# GCC PR#66871 again.
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$(obj)/system_certificates.o: $(obj)/signing_key.x509 |
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$(obj)/signing_key.x509: scripts/extract-cert include/config/module/sig/key.h $(X509_DEP) |
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$(call cmd,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY))
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endif |
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