[PATCH 3/4] certs: Add ability to preload revocation certs
Nathan Chancellor
nathan at kernel.org
Wed Mar 3 18:11:21 UTC 2021
On Thu, Feb 25, 2021 at 08:58:55PM +0000, David Howells wrote:
> From: Eric Snowberg <eric.snowberg at oracle.com>
>
> 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.
>
> [DH: Changed this to make the new Kconfig option depend on the option to
> enable the facility.]
>
> Signed-off-by: Eric Snowberg <eric.snowberg at oracle.com>
> Acked-by: Jarkko Sakkinen <jarkko.sakkinen at linux.intel.com>
> Signed-off-by: David Howells <dhowells at redhat.com>
> Link: https://lore.kernel.org/r/20200930201508.35113-3-eric.snowberg@oracle.com/
> Link: https://lore.kernel.org/r/20210122181054.32635-4-eric.snowberg@oracle.com/ # v5
> ---
>
> 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 76e469b56a77..ab88d2a7f3c7 100644
> --- a/certs/Kconfig
> +++ b/certs/Kconfig
> @@ -92,4 +92,12 @@ config SYSTEM_REVOCATION_LIST
> blacklist keyring and implements a hook whereby a PKCS#7 message can
> be checked to see if it matches such a certificate.
>
> +config SYSTEM_REVOCATION_KEYS
> + string "X.509 certificates to be preloaded into the system blacklist keyring"
> + depends on SYSTEM_REVOCATION_LIST
> + 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 2b8644123d5f..723b19c96256 100644
> --- a/certs/blacklist.c
> +++ b/certs/blacklist.c
> @@ -17,9 +17,13 @@
> #include <linux/uidgid.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.
> @@ -220,3 +224,16 @@ 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
>
>
This patch is broken when CONFIG_SYSTEM_BLACKLIST_KEYRING is set but
CONFIG_SYSTEM_REVOCATION_LIST is unset, meaning that
CONFIG_SYSTEM_REVOCATION_KEYS is not defined at all. This is very easy
to reproduce with x86_64_defconfig.
$ make -skj"$(nproc)" O=build/x86_64 defconfig
$ scripts/config --file build/x86_64/.config -e SYSTEM_BLACKLIST_KEYRING
$ make -skj"$(nproc)" O=build/x86_64 olddefconfig certs/
At main.c:154:
- SSL error:0909006C:PEM routines:get_name:no start line: crypto/pem/pem_lib.c:745
extract-cert: /home/nathan/cbl/src/linux-next/: Is a directory
make[3]: *** [/home/nathan/cbl/src/linux-next/certs/Makefile:119: certs/x509_revocation_list] Error 1
...
This happens with every single distribution configuration that I test.
Cheers,
Nathan
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