From 3f1e1bea34740069f70c6bc92d0f712345d5c28e Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 20 Jul 2015 21:16:27 +0100 Subject: MODSIGN: Use PKCS#7 messages as module signatures Move to using PKCS#7 messages as module signatures because: (1) We have to be able to support the use of X.509 certificates that don't have a subjKeyId set. We're currently relying on this to look up the X.509 certificate in the trusted keyring list. (2) PKCS#7 message signed information blocks have a field that supplies the data required to match with the X.509 certificate that signed it. (3) The PKCS#7 certificate carries fields that specify the digest algorithm used to generate the signature in a standardised way and the X.509 certificates specify the public key algorithm in a standardised way - so we don't need our own methods of specifying these. (4) We now have PKCS#7 message support in the kernel for signed kexec purposes and we can make use of this. To make this work, the old sign-file script has been replaced with a program that needs compiling in a previous patch. The rules to build it are added here. Signed-off-by: David Howells Tested-by: Vivek Goyal --- scripts/Makefile | 2 ++ 1 file changed, 2 insertions(+) (limited to 'scripts/Makefile') diff --git a/scripts/Makefile b/scripts/Makefile index 2016a64497ab..b12fe020664d 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -16,9 +16,11 @@ hostprogs-$(CONFIG_VT) += conmakehash hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable hostprogs-$(CONFIG_ASN1) += asn1_compiler +hostprogs-$(CONFIG_MODULE_SIG) += sign-file HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include +HOSTLOADLIBES_sign-file = -lcrypto always := $(hostprogs-y) $(hostprogs-m) -- cgit v1.2.3 From 1329e8cc69b93a0b1bc6d197b30dcff628c18dbf Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 20 Jul 2015 21:16:30 +0100 Subject: modsign: Extract signing cert from CONFIG_MODULE_SIG_KEY if needed Where an external PEM file or PKCS#11 URI is given, we can get the cert from it for ourselves instead of making the user drop signing_key.x509 in place for us. Signed-off-by: David Woodhouse Signed-off-by: David Howells --- Documentation/module-signing.txt | 11 ++-- init/Kconfig | 8 +-- kernel/Makefile | 38 +++++++++++ scripts/Makefile | 3 +- scripts/extract-cert.c | 132 +++++++++++++++++++++++++++++++++++++++ 5 files changed, 181 insertions(+), 11 deletions(-) create mode 100644 scripts/extract-cert.c (limited to 'scripts/Makefile') diff --git a/Documentation/module-signing.txt b/Documentation/module-signing.txt index 84597c7ea175..693001920890 100644 --- a/Documentation/module-signing.txt +++ b/Documentation/module-signing.txt @@ -93,17 +93,16 @@ This has a number of options available: Setting this option to something other than its default of "signing_key.priv" will disable the autogeneration of signing keys and allow the kernel modules to be signed with a key of your choosing. - The string provided should identify a file containing a private key - in PEM form, or — on systems where the OpenSSL ENGINE_pkcs11 is - appropriately installed — a PKCS#11 URI as defined by RFC7512. + The string provided should identify a file containing both a private + key and its corresponding X.509 certificate in PEM form, or — on + systems where the OpenSSL ENGINE_pkcs11 is functional — a PKCS#11 URI + as defined by RFC7512. In the latter case, the PKCS#11 URI should + reference both a certificate and a private key. If the PEM file containing the private key is encrypted, or if the PKCS#11 token requries a PIN, this can be provided at build time by means of the KBUILD_SIGN_PIN variable. - The corresponding X.509 certificate in DER form should still be placed - in a file named signing_key.x509 in the top-level build directory. - ======================= GENERATING SIGNING KEYS diff --git a/init/Kconfig b/init/Kconfig index 1b1148e9181b..e2e0a1d27886 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1953,10 +1953,10 @@ config MODULE_SIG_KEY default "signing_key.priv" depends on MODULE_SIG help - Provide the file name of a private key in PKCS#8 PEM format, or - a PKCS#11 URI according to RFC7512. The corresponding X.509 - certificate in DER form should be present in signing_key.x509 - in the top-level build directory. + 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. If this option is unchanged from its default "signing_key.priv", then the kernel will automatically generate the private key and diff --git a/kernel/Makefile b/kernel/Makefile index 2c937ace292e..fa2f8b84b18a 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -210,5 +210,43 @@ x509.genkey: @echo >>x509.genkey "keyUsage=digitalSignature" @echo >>x509.genkey "subjectKeyIdentifier=hash" @echo >>x509.genkey "authorityKeyIdentifier=keyid" +else +# For external (PKCS#11 or PEM) key, we need to obtain the certificate from +# CONFIG_MODULE_SIG_KEY automatically. +quiet_cmd_extract_der = CERT_DER $(2) + cmd_extract_der = scripts/extract-cert "$(2)" signing_key.x509 + +# CONFIG_MODULE_SIG_KEY is either a PKCS#11 URI or a filename. It is +# surrounded by quotes, and may contain spaces. To strip the quotes +# with $(patsubst) we need to turn the spaces into something else. +# And if it's a filename, those spaces need to be escaped as '\ ' in +# order to use it in dependencies or $(wildcard). +space := +space += +space_escape := %%%SPACE%%% +X509_SOURCE_temp := $(subst $(space),$(space_escape),$(CONFIG_MODULE_SIG_KEY)) +# We need this to check for absolute paths or PKCS#11 URIs. +X509_SOURCE_ONEWORD := $(patsubst "%",%,$(X509_SOURCE_temp)) +# This is the actual source filename/URI without the quotes +X509_SOURCE := $(subst $(space_escape),$(space),$(X509_SOURCE_ONEWORD)) +# This\ version\ with\ spaces\ escaped\ for\ $(wildcard)\ and\ dependencies +X509_SOURCE_ESCAPED := $(subst $(space_escape),\$(space),$(X509_SOURCE_ONEWORD)) + +ifeq ($(patsubst pkcs11:%,%,$(X509_SOURCE_ONEWORD)),$(X509_SOURCE_ONEWORD)) +# If it's a filename, depend on it. +X509_DEP := $(X509_SOURCE_ESCAPED) +ifeq ($(patsubst /%,%,$(X509_SOURCE_ONEWORD)),$(X509_SOURCE_ONEWORD)) +ifeq ($(wildcard $(X509_SOURCE_ESCAPED)),) +ifneq ($(wildcard $(srctree)/$(X509_SOURCE_ESCAPED)),) +# Non-absolute filename, found in source tree and not build tree +X509_SOURCE := $(srctree)/$(X509_SOURCE) +X509_DEP := $(srctree)/$(X509_SOURCE_ESCAPED) +endif +endif +endif +endif + +signing_key.x509: scripts/extract-cert include/config/module/sig/key.h $(X509_DEP) + $(call cmd,extract_der,$(X509_SOURCE)) endif endif diff --git a/scripts/Makefile b/scripts/Makefile index b12fe020664d..236f683510bd 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -16,11 +16,12 @@ hostprogs-$(CONFIG_VT) += conmakehash hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable hostprogs-$(CONFIG_ASN1) += asn1_compiler -hostprogs-$(CONFIG_MODULE_SIG) += sign-file +hostprogs-$(CONFIG_MODULE_SIG) += sign-file extract-cert HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include HOSTLOADLIBES_sign-file = -lcrypto +HOSTLOADLIBES_extract-cert = -lcrypto always := $(hostprogs-y) $(hostprogs-m) diff --git a/scripts/extract-cert.c b/scripts/extract-cert.c new file mode 100644 index 000000000000..4fd5b2f07b45 --- /dev/null +++ b/scripts/extract-cert.c @@ -0,0 +1,132 @@ +/* Extract X.509 certificate in DER form from PKCS#11 or PEM. + * + * Copyright © 2014 Red Hat, Inc. All Rights Reserved. + * Copyright © 2015 Intel Corporation. + * + * Authors: David Howells + * David Woodhouse + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define PKEY_ID_PKCS7 2 + +static __attribute__((noreturn)) +void format(void) +{ + fprintf(stderr, + "Usage: scripts/extract-cert \n"); + exit(2); +} + +static void display_openssl_errors(int l) +{ + const char *file; + char buf[120]; + int e, line; + + if (ERR_peek_error() == 0) + return; + fprintf(stderr, "At main.c:%d:\n", l); + + while ((e = ERR_get_error_line(&file, &line))) { + ERR_error_string(e, buf); + fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line); + } +} + +static void drain_openssl_errors(void) +{ + const char *file; + int line; + + if (ERR_peek_error() == 0) + return; + while (ERR_get_error_line(&file, &line)) {} +} + +#define ERR(cond, fmt, ...) \ + do { \ + bool __cond = (cond); \ + display_openssl_errors(__LINE__); \ + if (__cond) { \ + err(1, fmt, ## __VA_ARGS__); \ + } \ + } while(0) + +static const char *key_pass; + +int main(int argc, char **argv) +{ + char *cert_src, *cert_dst; + X509 *x509; + BIO *b; + + OpenSSL_add_all_algorithms(); + ERR_load_crypto_strings(); + ERR_clear_error(); + + key_pass = getenv("KBUILD_SIGN_PIN"); + + if (argc != 3) + format(); + + cert_src = argv[1]; + cert_dst = argv[2]; + + if (!strncmp(cert_src, "pkcs11:", 7)) { + ENGINE *e; + struct { + const char *cert_id; + X509 *cert; + } parms; + + parms.cert_id = cert_src; + parms.cert = NULL; + + ENGINE_load_builtin_engines(); + drain_openssl_errors(); + e = ENGINE_by_id("pkcs11"); + ERR(!e, "Load PKCS#11 ENGINE"); + if (ENGINE_init(e)) + drain_openssl_errors(); + else + ERR(1, "ENGINE_init"); + if (key_pass) + ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN"); + ENGINE_ctrl_cmd(e, "LOAD_CERT_CTRL", 0, &parms, NULL, 1); + ERR(!parms.cert, "Get X.509 from PKCS#11"); + x509 = parms.cert; + } else { + b = BIO_new_file(cert_src, "rb"); + ERR(!b, "%s", cert_src); + x509 = PEM_read_bio_X509(b, NULL, NULL, NULL); + ERR(!x509, "%s", cert_src); + BIO_free(b); + } + + b = BIO_new_file(cert_dst, "wb"); + ERR(!b, "%s", cert_dst); + ERR(!i2d_X509_bio(b, x509), cert_dst); + BIO_free(b); + + return 0; +} -- cgit v1.2.3 From 770f2b98760ef0500183d7206724aac762433e2d Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 20 Jul 2015 21:16:34 +0100 Subject: modsign: Use extract-cert to process CONFIG_SYSTEM_TRUSTED_KEYS Fix up the dependencies somewhat too, while we're at it. Signed-off-by: David Woodhouse Signed-off-by: David Howells --- kernel/Makefile | 25 ++++++++++++------------- kernel/system_certificates.S | 3 +++ scripts/Makefile | 3 ++- 3 files changed, 17 insertions(+), 14 deletions(-) (limited to 'scripts/Makefile') diff --git a/kernel/Makefile b/kernel/Makefile index 575329777d9e..65ef3846fbe8 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -166,23 +166,22 @@ endef # ############################################################################### - ifeq ($(CONFIG_SYSTEM_TRUSTED_KEYRING),y) $(eval $(call config_filename,SYSTEM_TRUSTED_KEYS)) -SIGNING_X509-$(CONFIG_MODULE_SIG) += signing_key.x509 - -kernel/system_certificates.o: $(obj)/x509_certificate_list +# GCC doesn't include .incbin files in -MD generated dependencies (PR#66871) +$(obj)/system_certificates.o: $(obj)/x509_certificate_list -quiet_cmd_x509certs = CERTS $(SIGNING_X509-y) $(patsubst "%",%,$(2)) - cmd_x509certs = ( cat $(SIGNING_X509-y) /dev/null; \ - awk '/-----BEGIN CERTIFICATE-----/{flag=1;next}/-----END CERTIFICATE-----/{flag=0}flag' $(2) /dev/null | base64 -d ) > $@ || ( rm $@; exit 1) +# Cope with signing_key.x509 existing in $(srctree) not $(objtree) +AFLAGS_system_certificates.o := -I$(srctree) -targets += $(obj)/x509_certificate_list -$(obj)/x509_certificate_list: $(SIGNING_X509-y) include/config/system/trusted/keys.h $(wildcard include/config/module/sig.h) $(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(SYSTEM_TRUSTED_KEYS_FILENAME) - $(call if_changed,x509certs,$(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_TRUSTED_KEYS)) +quiet_cmd_extract_certs = EXTRACT_CERTS $(patsubst "%",%,$(2)) + cmd_extract_certs = scripts/extract-cert $(2) $@ || ( rm $@; exit 1) +targets += x509_certificate_list +$(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)$(CONFIG_SYSTEM_TRUSTED_KEYS)) endif clean-files := x509_certificate_list .x509.list @@ -248,9 +247,9 @@ ifeq ($(patsubst pkcs11:%,%,$(firstword $(MODULE_SIG_KEY_FILENAME))),$(firstword X509_DEP := $(MODULE_SIG_KEY_SRCPREFIX)$(MODULE_SIG_KEY_FILENAME) endif -quiet_cmd_extract_der = SIGNING_CERT $(patsubst "%",%,$(2)) - cmd_extract_der = scripts/extract-cert $(2) signing_key.x509 +# GCC PR#66871 again. +$(obj)/system_certificates.o: signing_key.x509 signing_key.x509: scripts/extract-cert include/config/module/sig/key.h $(X509_DEP) - $(call cmd,extract_der,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY)) + $(call cmd,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY)) endif diff --git a/kernel/system_certificates.S b/kernel/system_certificates.S index 3e9868d47535..6ba2f75e7ba5 100644 --- a/kernel/system_certificates.S +++ b/kernel/system_certificates.S @@ -7,6 +7,9 @@ .globl VMLINUX_SYMBOL(system_certificate_list) VMLINUX_SYMBOL(system_certificate_list): __cert_list_start: +#ifdef CONFIG_MODULE_SIG + .incbin "signing_key.x509" +#endif .incbin "kernel/x509_certificate_list" __cert_list_end: diff --git a/scripts/Makefile b/scripts/Makefile index 236f683510bd..1b2661712d44 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -16,7 +16,8 @@ hostprogs-$(CONFIG_VT) += conmakehash hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable hostprogs-$(CONFIG_ASN1) += asn1_compiler -hostprogs-$(CONFIG_MODULE_SIG) += sign-file extract-cert +hostprogs-$(CONFIG_MODULE_SIG) += sign-file +hostprogs-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += extract-cert HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include -- cgit v1.2.3