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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: David Howells <[email protected]> Reviewed-by: David Woodhouse <[email protected]>
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Original file line number | Diff line number | Diff line change |
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@@ -2589,6 +2589,15 @@ S: Supported | |
F: Documentation/filesystems/ceph.txt | ||
F: fs/ceph/ | ||
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CERTIFICATE HANDLING: | ||
M: David Howells <[email protected]> | ||
M: David Woodhouse <[email protected]> | ||
L: [email protected] | ||
S: Maintained | ||
F: Documentation/module-signing.txt | ||
F: certs/ | ||
F: scripts/extract-cert.c | ||
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CERTIFIED WIRELESS USB (WUSB) SUBSYSTEM: | ||
L: [email protected] | ||
S: Orphan | ||
|
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menu "Certificates for signature checking" | ||
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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. | ||
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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 | ||
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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. | ||
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Keys in this keyring are used by module signature checking. | ||
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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. | ||
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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. | ||
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endmenu |
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# | ||
# Makefile for the linux kernel signature checking certificates. | ||
# | ||
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obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o | ||
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############################################################################### | ||
# | ||
# 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 := $(srctree)/ | ||
endif | ||
endif | ||
endif | ||
endif | ||
endef | ||
# | ||
############################################################################### | ||
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ifeq ($(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) | ||
$(obj)/system_certificates.o: $(obj)/x509_certificate_list | ||
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# Cope with signing_key.x509 existing in $(srctree) not $(objtree) | ||
AFLAGS_system_certificates.o := -I$(srctree) | ||
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quiet_cmd_extract_certs = EXTRACT_CERTS $(patsubst "%",%,$(2)) | ||
cmd_extract_certs = scripts/extract-cert $(2) $@ || ( rm $@; exit 1) | ||
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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)$(CONFIG_SYSTEM_TRUSTED_KEYS)) | ||
endif | ||
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clean-files := x509_certificate_list .x509.list | ||
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ifeq ($(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 | ||
$(error Could not determine digest type to use from kernel config) | ||
endif | ||
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# We do it this way rather than having a boolean option for enabling an | ||
# external private key, because 'make randconfig' might enable such a | ||
# boolean option and we unfortunately can't make it depend on !RANDCONFIG. | ||
ifeq ($(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 $(obj)/signing_key.pem 2>&1 | ||
@echo "###" | ||
@echo "### Key pair generated." | ||
@echo "###" | ||
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$(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 >>$@ "#emailAddress = [email protected]" | ||
@echo >>$@ | ||
@echo >>$@ "[ myexts ]" | ||
@echo >>$@ "basicConstraints=critical,CA:FALSE" | ||
@echo >>$@ "keyUsage=digitalSignature" | ||
@echo >>$@ "subjectKeyIdentifier=hash" | ||
@echo >>$@ "authorityKeyIdentifier=keyid" | ||
endif | ||
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$(eval $(call config_filename,MODULE_SIG_KEY)) | ||
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# If CONFIG_MODULE_SIG_KEY isn't a PKCS#11 URI, depend on it | ||
ifeq ($(patsubst pkcs11:%,%,$(firstword $(MODULE_SIG_KEY_FILENAME))),$(firstword $(MODULE_SIG_KEY_FILENAME))) | ||
X509_DEP := $(MODULE_SIG_KEY_SRCPREFIX)$(MODULE_SIG_KEY_FILENAME) | ||
endif | ||
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# GCC PR#66871 again. | ||
$(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) | ||
$(call cmd,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY)) | ||
endif |
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