@@ -4118,6 +4118,7 @@ L: keyrings@vger.kernel.org
S: Maintained
F: Documentation/admin-guide/module-signing.rst
F: certs/
+F: scripts/check-blacklist-hashes.awk
F: scripts/extract-cert.c
F: scripts/sign-file.c
F: tools/certs/
@@ -1,2 +1,3 @@
# SPDX-License-Identifier: GPL-2.0-only
+blacklist_hashes_checked
x509_certificate_list
@@ -80,8 +80,11 @@ config SYSTEM_BLACKLIST_HASH_LIST
help
If set, this option should be the filename of a list of hashes in the
form "<hash>", "<hash>", ... . This will be included into a C
- wrapper to incorporate the list into the kernel. Each <hash> should
- be a string of hex digits.
+ wrapper to incorporate the list into the kernel. Each <hash> must be a
+ string starting with a prefix ("tbs" or "bin"), then a colon (":"), and
+ finally an even number of hexadecimal lowercase characters (up to 128).
+ Certificate hashes can be generated with
+ tools/certs/print-cert-tbs-hash.sh .
config SYSTEM_REVOCATION_KEYS
string "X.509 certificates to be preloaded into the system blacklist keyring"
@@ -6,7 +6,22 @@
obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o common.o
obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist.o revocation_certificates.o common.o
ifneq ($(CONFIG_SYSTEM_BLACKLIST_HASH_LIST),"")
+
+quiet_cmd_check_blacklist_hashes = CHECK $(patsubst "%",%,$(2))
+ cmd_check_blacklist_hashes = $(AWK) -f $(srctree)/scripts/check-blacklist-hashes.awk $(2); touch $@
+
+$(eval $(call config_filename,SYSTEM_BLACKLIST_HASH_LIST))
+
+$(obj)/blacklist_hashes.o: $(obj)/blacklist_hashes_checked
+
+CFLAGS_blacklist_hashes.o += -I$(srctree)
+
+targets += blacklist_hashes_checked
+$(obj)/blacklist_hashes_checked: $(SYSTEM_BLACKLIST_HASH_LIST_SRCPREFIX)$(SYSTEM_BLACKLIST_HASH_LIST_FILENAME) scripts/check-blacklist-hashes.awk FORCE
+ $(call if_changed,check_blacklist_hashes,$(SYSTEM_BLACKLIST_HASH_LIST_SRCPREFIX)$(CONFIG_SYSTEM_BLACKLIST_HASH_LIST))
+
obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_hashes.o
+
else
obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_nohashes.o
endif
@@ -29,7 +44,7 @@ $(obj)/x509_certificate_list: scripts/extract-cert $(SYSTEM_TRUSTED_KEYS_SRCPREF
$(call if_changed,extract_certs,$(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_TRUSTED_KEYS))
endif # CONFIG_SYSTEM_TRUSTED_KEYRING
-clean-files := x509_certificate_list .x509.list x509_revocation_list
+clean-files := x509_certificate_list .x509.list x509_revocation_list blacklist_hashes_checked
ifeq ($(CONFIG_MODULE_SIG),y)
###############################################################################
new file mode 100755
@@ -0,0 +1,37 @@
+#!/usr/bin/awk -f
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright © 2020, Microsoft Corporation. All rights reserved.
+#
+# Author: Mickaël Salaün <mic@linux.microsoft.com>
+#
+# Check that a CONFIG_SYSTEM_BLACKLIST_HASH_LIST file contains a valid array of
+# hash strings. Such string must start with a prefix ("tbs" or "bin"), then a
+# colon (":"), and finally an even number of hexadecimal lowercase characters
+# (up to 128).
+
+BEGIN {
+ RS = ","
+}
+{
+ if (!match($0, "^[ \t\n\r]*\"([^\"]*)\"[ \t\n\r]*$", part1)) {
+ print "Not a string (item " NR "):", $0;
+ exit 1;
+ }
+ if (!match(part1[1], "^(tbs|bin):(.*)$", part2)) {
+ print "Unknown prefix (item " NR "):", part1[1];
+ exit 1;
+ }
+ if (!match(part2[2], "^([0-9a-f]+)$", part3)) {
+ print "Not a lowercase hexadecimal string (item " NR "):", part2[2];
+ exit 1;
+ }
+ if (length(part3[1]) > 128) {
+ print "Hash string too long (item " NR "):", part3[1];
+ exit 1;
+ }
+ if (length(part3[1]) % 2 == 1) {
+ print "Not an even number of hexadecimal characters (item " NR "):", part3[1];
+ exit 1;
+ }
+}