On Fri, Mar 12, 2021 at 06:12:29PM +0100, Mickaël Salaün wrote: > From: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> > > Add and use a check-blacklist-hashes.awk script to make sure that the > builtin blacklist hashes set with CONFIG_SYSTEM_BLACKLIST_HASH_LIST will > effectively be taken into account as blacklisted hashes. This is useful > to debug invalid hash formats, and it make sure that previous hashes > which could have been loaded in the kernel, but silently ignored, are > now noticed and deal with by the user at kernel build time. > > This also prevent stricter blacklist key description checking (provided > by following commits) to failed for builtin hashes. > > Update CONFIG_SYSTEM_BLACKLIST_HASH_LIST help to explain the content of > a hash string and how to generate certificate ones. > > Cc: David Howells <dhowells@xxxxxxxxxx> > Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx> > Cc: Eric Snowberg <eric.snowberg@xxxxxxxxxx> > Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> > Link: https://lore.kernel.org/r/20210312171232.2681989-3-mic@xxxxxxxxxxx Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> /Jarkko > --- > > Changes since v5: > * Rebase on keys-next and fix conflict as previously done by David > Howells. > * Enable to use a file path relative to the kernel source directory. > This align with the handling of CONFIG_SYSTEM_TRUSTED_KEYS, > CONFIG_MODULE_SIG_KEY and CONFIG_SYSTEM_REVOCATION_KEYS. > > Changes since v3: > * Improve commit description. > * Update CONFIG_SYSTEM_BLACKLIST_HASH_LIST help. > * Remove Acked-by Jarkko Sakkinen because of the above changes. > > Changes since v2: > * Add Jarkko's Acked-by. > > Changes since v1: > * Prefix script path with $(scrtree)/ (suggested by David Howells). > * Fix hexadecimal number check. > --- > MAINTAINERS | 1 + > certs/.gitignore | 1 + > certs/Kconfig | 7 ++++-- > certs/Makefile | 17 +++++++++++++- > scripts/check-blacklist-hashes.awk | 37 ++++++++++++++++++++++++++++++ > 5 files changed, 60 insertions(+), 3 deletions(-) > create mode 100755 scripts/check-blacklist-hashes.awk > > diff --git a/MAINTAINERS b/MAINTAINERS > index 773a362e807f..a18fd3d283c6 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -4118,6 +4118,7 @@ L: keyrings@xxxxxxxxxxxxxxx > S: Maintained > F: Documentation/admin-guide/module-signing.rst > F: certs/ > +F: scripts/check-blacklist-hashes.awk > F: scripts/extract-cert.c > F: scripts/sign-file.c > F: tools/certs/ > diff --git a/certs/.gitignore b/certs/.gitignore > index 2a2483990686..42cc2ac24b93 100644 > --- a/certs/.gitignore > +++ b/certs/.gitignore > @@ -1,2 +1,3 @@ > # SPDX-License-Identifier: GPL-2.0-only > +blacklist_hashes_checked > x509_certificate_list > diff --git a/certs/Kconfig b/certs/Kconfig > index ab88d2a7f3c7..cf3740c1b22b 100644 > --- a/certs/Kconfig > +++ b/certs/Kconfig > @@ -80,8 +80,11 @@ config SYSTEM_BLACKLIST_HASH_LIST > help > If set, this option should be the filename of a list of hashes in the > form "<hash>", "<hash>", ... . This will be included into a C > - wrapper to incorporate the list into the kernel. Each <hash> should > - be a string of hex digits. > + wrapper to incorporate the list into the kernel. Each <hash> must be a > + string starting with a prefix ("tbs" or "bin"), then a colon (":"), and > + finally an even number of hexadecimal lowercase characters (up to 128). > + Certificate hashes can be generated with > + tools/certs/print-cert-tbs-hash.sh . > > config SYSTEM_REVOCATION_LIST > bool "Provide system-wide ring of revocation certificates" > diff --git a/certs/Makefile b/certs/Makefile > index b6db52ebf0be..61e82b8eacd2 100644 > --- a/certs/Makefile > +++ b/certs/Makefile > @@ -7,7 +7,22 @@ obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o c > obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist.o common.o > obj-$(CONFIG_SYSTEM_REVOCATION_LIST) += revocation_certificates.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 > @@ -30,7 +45,7 @@ $(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) > ############################################################################### > diff --git a/scripts/check-blacklist-hashes.awk b/scripts/check-blacklist-hashes.awk > new file mode 100755 > index 000000000000..107c1d3204d4 > --- /dev/null > +++ b/scripts/check-blacklist-hashes.awk > @@ -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@xxxxxxxxxxxxxxxxxxx> > +# > +# 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; > + } > +} > -- > 2.30.2 > >
