[PATCH v5 3/4] certs: Add ability to preload revocation certs

Eric Snowberg
2021-01-22T18:39:50Z

Add a new Kconfig option called SYSTEM_REVOCATION_KEYS. If set,
this option should be the filename of a PEM-formated file containing
X.509 certificates to be included in the default blacklist keyring.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
certs/Kconfig | 8 ++++++++
certs/Makefile | 18 ++++++++++++++++--
certs/blacklist.c | 17 +++++++++++++++++
certs/revocation_certificates.S | 21 +++++++++++++++++++++
scripts/Makefile | 1 +
5 files changed, 63 insertions(+), 2 deletions(-)
create mode 100644 certs/revocation_certificates.S

diff --git a/certs/Kconfig b/certs/Kconfig
index c94e93d8bccf..379a6e198459 100644
--- a/certs/Kconfig
+++ b/certs/Kconfig
@@ -83,4 +83,12 @@ config SYSTEM_BLACKLIST_HASH_LIST
wrapper to incorporate the list into the kernel. Each <hash> should
be a string of hex digits.

+config SYSTEM_REVOCATION_KEYS
+ string "X.509 certificates to be preloaded into the system blacklist keyring"
+ depends on SYSTEM_BLACKLIST_KEYRING
+ help
+ If set, this option should be the filename of a PEM-formatted file
+ containing X.509 certificates to be included in the default blacklist
+ keyring.
+
endmenu
diff --git a/certs/Makefile b/certs/Makefile
index f4b90bad8690..e3f4926fd21e 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -4,7 +4,7 @@
#

obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o common.o
-obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist.o
+obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist.o revocation_certificates.o common.o
ifneq ($(CONFIG_SYSTEM_BLACKLIST_HASH_LIST),"")
obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_hashes.o
else
@@ -29,7 +29,7 @@ $(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
+clean-files := x509_certificate_list .x509.list x509_revocation_list

ifeq ($(CONFIG_MODULE_SIG),y)
###############################################################################
@@ -104,3 +104,17 @@ targets += signing_key.x509
$(obj)/signing_key.x509: scripts/extract-cert $(X509_DEP) FORCE
$(call if_changed,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY))
endif # CONFIG_MODULE_SIG
+
+ifeq ($(CONFIG_SYSTEM_BLACKLIST_KEYRING),y)
+
+$(eval $(call config_filename,SYSTEM_REVOCATION_KEYS))
+
+$(obj)/revocation_certificates.o: $(obj)/x509_revocation_list
+
+quiet_cmd_extract_certs = EXTRACT_CERTS $(patsubst "%",%,$(2))
+ cmd_extract_certs = scripts/extract-cert $(2) $@
+
+targets += x509_revocation_list
+$(obj)/x509_revocation_list: scripts/extract-cert $(SYSTEM_REVOCATION_KEYS_SRCPREFIX)$(SYSTEM_REVOCATION_KEYS_FILENAME) FORCE
+ $(call if_changed,extract_certs,$(SYSTEM_REVOCATION_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_REVOCATION_KEYS))
+endif
diff --git a/certs/blacklist.c b/certs/blacklist.c
index a7f021878a4b..4e8a1068adb2 100644
--- a/certs/blacklist.c
+++ b/certs/blacklist.c
@@ -16,9 +16,13 @@
#include <linux/seq_file.h>
#include <keys/system_keyring.h>
#include "blacklist.h"
+#include "common.h"

static struct key *blacklist_keyring;

+extern __initconst const u8 revocation_certificate_list[];
+extern __initconst const unsigned long revocation_certificate_list_size;
+
/*
* The description must be a type prefix, a colon and then an even number of
* hex digits. The hash is kept in the description.
@@ -209,3 +213,16 @@ static int __init blacklist_init(void)
* Must be initialised before we try and load the keys into the keyring.
*/
device_initcall(blacklist_init);
+
+/*
+ * Load the compiled-in list of revocation X.509 certificates.
+ */
+static __init int load_revocation_certificate_list(void)
+{
+ if (revocation_certificate_list_size)
+ pr_notice("Loading compiled-in revocation X.509 certificates\n");
+
+ return load_certificate_list(revocation_certificate_list, revocation_certificate_list_size,
+ blacklist_keyring);
+}
+late_initcall(load_revocation_certificate_list);
diff --git a/certs/revocation_certificates.S b/certs/revocation_certificates.S
new file mode 100644
index 000000000000..f21aae8a8f0e
--- /dev/null
+++ b/certs/revocation_certificates.S
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/export.h>
+#include <linux/init.h>
+
+ __INITRODATA
+
+ .align 8
+ .globl revocation_certificate_list
+revocation_certificate_list:
+__revocation_list_start:
+ .incbin "certs/x509_revocation_list"
+__revocation_list_end:
+
+ .align 8
+ .globl revocation_certificate_list_size
+revocation_certificate_list_size:
+#ifdef CONFIG_64BIT
+ .quad __revocation_list_end - __revocation_list_start
+#else
+ .long __revocation_list_end - __revocation_list_start
+#endif
diff --git a/scripts/Makefile b/scripts/Makefile
index b5418ec587fb..983b785f13cb 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -11,6 +11,7 @@ hostprogs-always-$(CONFIG_ASN1) += asn1_compiler
hostprogs-always-$(CONFIG_MODULE_SIG_FORMAT) += sign-file
hostprogs-always-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += extract-cert
hostprogs-always-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert
+ hostprogs-always-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += extract-cert

HOSTCFLAGS_sorttable.o = -I$(srctree)/tools/include
HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include
--
2.18.4