diff options
Diffstat (limited to 'certs')
| -rw-r--r-- | certs/.gitignore | 5 | ||||
| -rw-r--r-- | certs/Kconfig | 141 | ||||
| -rw-r--r-- | certs/Makefile | 88 | ||||
| -rw-r--r-- | certs/blacklist.c | 372 | ||||
| -rw-r--r-- | certs/blacklist.h | 5 | ||||
| -rw-r--r-- | certs/blacklist_hashes.c | 6 | ||||
| -rwxr-xr-x | certs/check-blacklist-hashes.awk | 37 | ||||
| -rw-r--r-- | certs/default_x509.genkey | 17 | ||||
| -rw-r--r-- | certs/extract-cert.c | 169 | ||||
| -rw-r--r-- | certs/revocation_certificates.S | 21 | ||||
| -rw-r--r-- | certs/system_certificates.S | 46 | ||||
| -rw-r--r-- | certs/system_keyring.c | 341 |
12 files changed, 1248 insertions, 0 deletions
diff --git a/certs/.gitignore b/certs/.gitignore new file mode 100644 index 000000000..cec5465f3 --- /dev/null +++ b/certs/.gitignore @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0-only +/blacklist_hash_list +/extract-cert +/x509_certificate_list +/x509_revocation_list diff --git a/certs/Kconfig b/certs/Kconfig new file mode 100644 index 000000000..1f109b070 --- /dev/null +++ b/certs/Kconfig @@ -0,0 +1,141 @@ +# SPDX-License-Identifier: GPL-2.0 +menu "Certificates for signature checking" + +config MODULE_SIG_KEY + string "File name or PKCS#11 URI of module signing key" + default "certs/signing_key.pem" + depends on MODULE_SIG || (IMA_APPRAISE_MODSIG && MODULES) + help + 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 "certs/signing_key.pem", + then the kernel will automatically generate the private key and + certificate as described in Documentation/admin-guide/module-signing.rst + +choice + prompt "Type of module signing key to be generated" + depends on MODULE_SIG || (IMA_APPRAISE_MODSIG && MODULES) + help + The type of module signing key type to generate. This option + does not apply if a #PKCS11 URI is used. + +config MODULE_SIG_KEY_TYPE_RSA + bool "RSA" + help + Use an RSA key for module signing. + +config MODULE_SIG_KEY_TYPE_ECDSA + bool "ECDSA" + select CRYPTO_ECDSA + help + Use an elliptic curve key (NIST P384) for module signing. Consider + using a strong hash like sha256 or sha384 for hashing modules. + + Note: Remove all ECDSA signing keys, e.g. certs/signing_key.pem, + when falling back to building Linux 5.14 and older kernels. + +endchoice + +config SYSTEM_TRUSTED_KEYRING + bool "Provide system-wide ring of trusted keys" + depends on KEYS + depends on ASYMMETRIC_KEY_TYPE + depends on X509_CERTIFICATE_PARSER = y + help + Provide a system keyring to which trusted keys can be added. Keys in + the keyring are considered to be trusted. Keys may be added at will + by the kernel from compiled-in data and from hardware key stores, but + userspace may only add extra keys if those keys can be verified by + keys already in the keyring. + + Keys in this keyring are used by module signature checking. + +config SYSTEM_TRUSTED_KEYS + string "Additional X.509 keys for default system keyring" + depends on SYSTEM_TRUSTED_KEYRING + help + If set, this option should be the filename of a PEM-formatted file + containing trusted X.509 certificates to be included in the default + system keyring. Any certificate used for module signing is implicitly + also trusted. + + NOTE: If you previously provided keys for the system keyring in the + form of DER-encoded *.x509 files in the top-level build directory, + those are no longer used. You will need to set this option instead. + +config SYSTEM_EXTRA_CERTIFICATE + bool "Reserve area for inserting a certificate without recompiling" + depends on SYSTEM_TRUSTED_KEYRING + help + If set, space for an extra certificate will be reserved in the kernel + image. This allows introducing a trusted certificate to the default + system keyring without recompiling the kernel. + +config SYSTEM_EXTRA_CERTIFICATE_SIZE + int "Number of bytes to reserve for the extra certificate" + depends on SYSTEM_EXTRA_CERTIFICATE + default 4096 + help + This is the number of bytes reserved in the kernel image for a + certificate to be inserted. + +config SECONDARY_TRUSTED_KEYRING + bool "Provide a keyring to which extra trustable keys may be added" + depends on SYSTEM_TRUSTED_KEYRING + help + If set, provide a keyring to which extra keys may be added, provided + those keys are not blacklisted and are vouched for by a key built + into the kernel or already in the secondary trusted keyring. + +config SYSTEM_BLACKLIST_KEYRING + bool "Provide system-wide ring of blacklisted keys" + depends on KEYS + help + Provide a system keyring to which blacklisted keys can be added. + Keys in the keyring are considered entirely untrusted. Keys in this + keyring are used by the module signature checking to reject loading + of modules signed with a blacklisted key. + +config SYSTEM_BLACKLIST_HASH_LIST + string "Hashes to be preloaded into the system blacklist keyring" + depends on SYSTEM_BLACKLIST_KEYRING + 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> 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" + depends on SYSTEM_BLACKLIST_KEYRING + depends on PKCS7_MESSAGE_PARSER=y + help + If set, this allows revocation certificates to be stored in the + 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. + +config SYSTEM_BLACKLIST_AUTH_UPDATE + bool "Allow root to add signed blacklist keys" + depends on SYSTEM_BLACKLIST_KEYRING + depends on SYSTEM_DATA_VERIFICATION + help + If set, provide the ability to load new blacklist keys at run time if + they are signed and vouched by a certificate from the builtin trusted + keyring. The PKCS#7 signature of the description is set in the key + payload. Blacklist keys cannot be removed. + +endmenu diff --git a/certs/Makefile b/certs/Makefile new file mode 100644 index 000000000..799ad7b9e --- /dev/null +++ b/certs/Makefile @@ -0,0 +1,88 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Makefile for the linux kernel signature checking certificates. +# + +obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o +obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist.o blacklist_hashes.o +obj-$(CONFIG_SYSTEM_REVOCATION_LIST) += revocation_certificates.o + +$(obj)/blacklist_hashes.o: $(obj)/blacklist_hash_list +CFLAGS_blacklist_hashes.o := -I $(obj) + +quiet_cmd_check_and_copy_blacklist_hash_list = GEN $@ + cmd_check_and_copy_blacklist_hash_list = \ + $(if $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST), \ + $(AWK) -f $(srctree)/$(src)/check-blacklist-hashes.awk $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST) >&2; \ + { cat $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST); echo $(comma) NULL; } > $@, \ + echo NULL > $@) + +$(obj)/blacklist_hash_list: $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST) FORCE + $(call if_changed,check_and_copy_blacklist_hash_list) + +targets += blacklist_hash_list + +quiet_cmd_extract_certs = CERT $@ + cmd_extract_certs = $(obj)/extract-cert "$(extract-cert-in)" $@ +extract-cert-in = $(filter-out $(obj)/extract-cert, $(real-prereqs)) + +$(obj)/system_certificates.o: $(obj)/x509_certificate_list + +$(obj)/x509_certificate_list: $(CONFIG_SYSTEM_TRUSTED_KEYS) $(obj)/extract-cert FORCE + $(call if_changed,extract_certs) + +targets += x509_certificate_list + +# If module signing is requested, say by allyesconfig, but a key has not been +# supplied, then one will need to be generated to make sure the build does not +# fail and that the kernel may be used afterwards. +# +# We do it this way rather than having a boolean option for enabling an +# external private key, because 'make randconfig' might enable such a +# boolean option and we unfortunately can't make it depend on !RANDCONFIG. +ifeq ($(CONFIG_MODULE_SIG_KEY),certs/signing_key.pem) + +keytype-$(CONFIG_MODULE_SIG_KEY_TYPE_ECDSA) := -newkey ec -pkeyopt ec_paramgen_curve:secp384r1 + +quiet_cmd_gen_key = GENKEY $@ + cmd_gen_key = openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \ + -batch -x509 -config $< \ + -outform PEM -out $@ -keyout $@ $(keytype-y) 2>&1 + +$(obj)/signing_key.pem: $(obj)/x509.genkey FORCE + $(call if_changed,gen_key) + +targets += signing_key.pem + +quiet_cmd_copy_x509_config = COPY $@ + cmd_copy_x509_config = cat $(srctree)/$(src)/default_x509.genkey > $@ + +# You can provide your own config file. If not present, copy the default one. +$(obj)/x509.genkey: + $(call cmd,copy_x509_config) + +endif # CONFIG_MODULE_SIG_KEY + +$(obj)/system_certificates.o: $(obj)/signing_key.x509 + +PKCS11_URI := $(filter pkcs11:%, $(CONFIG_MODULE_SIG_KEY)) +ifdef PKCS11_URI +$(obj)/signing_key.x509: extract-cert-in := $(PKCS11_URI) +endif + +$(obj)/signing_key.x509: $(filter-out $(PKCS11_URI),$(CONFIG_MODULE_SIG_KEY)) $(obj)/extract-cert FORCE + $(call if_changed,extract_certs) + +targets += signing_key.x509 + +$(obj)/revocation_certificates.o: $(obj)/x509_revocation_list + +$(obj)/x509_revocation_list: $(CONFIG_SYSTEM_REVOCATION_KEYS) $(obj)/extract-cert FORCE + $(call if_changed,extract_certs) + +targets += x509_revocation_list + +hostprogs := extract-cert + +HOSTCFLAGS_extract-cert.o = $(shell $(HOSTPKG_CONFIG) --cflags libcrypto 2> /dev/null) +HOSTLDLIBS_extract-cert = $(shell $(HOSTPKG_CONFIG) --libs libcrypto 2> /dev/null || echo -lcrypto) diff --git a/certs/blacklist.c b/certs/blacklist.c new file mode 100644 index 000000000..41f10601c --- /dev/null +++ b/certs/blacklist.c @@ -0,0 +1,372 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* System hash blacklist. + * + * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#define pr_fmt(fmt) "blacklist: "fmt +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/key.h> +#include <linux/key-type.h> +#include <linux/sched.h> +#include <linux/ctype.h> +#include <linux/err.h> +#include <linux/seq_file.h> +#include <linux/uidgid.h> +#include <keys/asymmetric-type.h> +#include <keys/system_keyring.h> +#include "blacklist.h" + +/* + * According to crypto/asymmetric_keys/x509_cert_parser.c:x509_note_pkey_algo(), + * the size of the currently longest supported hash algorithm is 512 bits, + * which translates into 128 hex characters. + */ +#define MAX_HASH_LEN 128 + +#define BLACKLIST_KEY_PERM (KEY_POS_SEARCH | KEY_POS_VIEW | \ + KEY_USR_SEARCH | KEY_USR_VIEW) + +static const char tbs_prefix[] = "tbs"; +static const char bin_prefix[] = "bin"; + +static struct key *blacklist_keyring; + +#ifdef CONFIG_SYSTEM_REVOCATION_LIST +extern __initconst const u8 revocation_certificate_list[]; +extern __initconst const unsigned long revocation_certificate_list_size; +#endif + +/* + * The description must be a type prefix, a colon and then an even number of + * hex digits. The hash is kept in the description. + */ +static int blacklist_vet_description(const char *desc) +{ + int i, prefix_len, tbs_step = 0, bin_step = 0; + + /* The following algorithm only works if prefix lengths match. */ + BUILD_BUG_ON(sizeof(tbs_prefix) != sizeof(bin_prefix)); + prefix_len = sizeof(tbs_prefix) - 1; + for (i = 0; *desc; desc++, i++) { + if (*desc == ':') { + if (tbs_step == prefix_len) + goto found_colon; + if (bin_step == prefix_len) + goto found_colon; + return -EINVAL; + } + if (i >= prefix_len) + return -EINVAL; + if (*desc == tbs_prefix[i]) + tbs_step++; + if (*desc == bin_prefix[i]) + bin_step++; + } + return -EINVAL; + +found_colon: + desc++; + for (i = 0; *desc && i < MAX_HASH_LEN; desc++, i++) { + if (!isxdigit(*desc) || isupper(*desc)) + return -EINVAL; + } + if (*desc) + /* The hash is greater than MAX_HASH_LEN. */ + return -ENOPKG; + + /* Checks for an even number of hexadecimal characters. */ + if (i == 0 || i & 1) + return -EINVAL; + return 0; +} + +static int blacklist_key_instantiate(struct key *key, + struct key_preparsed_payload *prep) +{ +#ifdef CONFIG_SYSTEM_BLACKLIST_AUTH_UPDATE + int err; +#endif + + /* Sets safe default permissions for keys loaded by user space. */ + key->perm = BLACKLIST_KEY_PERM; + + /* + * Skips the authentication step for builtin hashes, they are not + * signed but still trusted. + */ + if (key->flags & (1 << KEY_FLAG_BUILTIN)) + goto out; + +#ifdef CONFIG_SYSTEM_BLACKLIST_AUTH_UPDATE + /* + * Verifies the description's PKCS#7 signature against the builtin + * trusted keyring. + */ + err = verify_pkcs7_signature(key->description, + strlen(key->description), prep->data, prep->datalen, + NULL, VERIFYING_UNSPECIFIED_SIGNATURE, NULL, NULL); + if (err) + return err; +#else + /* + * It should not be possible to come here because the keyring doesn't + * have KEY_USR_WRITE and the only other way to call this function is + * for builtin hashes. + */ + WARN_ON_ONCE(1); + return -EPERM; +#endif + +out: + return generic_key_instantiate(key, prep); +} + +static int blacklist_key_update(struct key *key, + struct key_preparsed_payload *prep) +{ + return -EPERM; +} + +static void blacklist_describe(const struct key *key, struct seq_file *m) +{ + seq_puts(m, key->description); +} + +static struct key_type key_type_blacklist = { + .name = "blacklist", + .vet_description = blacklist_vet_description, + .instantiate = blacklist_key_instantiate, + .update = blacklist_key_update, + .describe = blacklist_describe, +}; + +static char *get_raw_hash(const u8 *hash, size_t hash_len, + enum blacklist_hash_type hash_type) +{ + size_t type_len; + const char *type_prefix; + char *buffer, *p; + + switch (hash_type) { + case BLACKLIST_HASH_X509_TBS: + type_len = sizeof(tbs_prefix) - 1; + type_prefix = tbs_prefix; + break; + case BLACKLIST_HASH_BINARY: + type_len = sizeof(bin_prefix) - 1; + type_prefix = bin_prefix; + break; + default: + WARN_ON_ONCE(1); + return ERR_PTR(-EINVAL); + } + buffer = kmalloc(type_len + 1 + hash_len * 2 + 1, GFP_KERNEL); + if (!buffer) + return ERR_PTR(-ENOMEM); + p = memcpy(buffer, type_prefix, type_len); + p += type_len; + *p++ = ':'; + bin2hex(p, hash, hash_len); + p += hash_len * 2; + *p = '\0'; + return buffer; +} + +/** + * mark_raw_hash_blacklisted - Add a hash to the system blacklist + * @hash: The hash as a hex string with a type prefix (eg. "tbs:23aa429783") + */ +static int mark_raw_hash_blacklisted(const char *hash) +{ + key_ref_t key; + + key = key_create_or_update(make_key_ref(blacklist_keyring, true), + "blacklist", + hash, + NULL, + 0, + BLACKLIST_KEY_PERM, + KEY_ALLOC_NOT_IN_QUOTA | + KEY_ALLOC_BUILT_IN); + if (IS_ERR(key)) { + pr_err("Problem blacklisting hash (%ld)\n", PTR_ERR(key)); + return PTR_ERR(key); + } + return 0; +} + +int mark_hash_blacklisted(const u8 *hash, size_t hash_len, + enum blacklist_hash_type hash_type) +{ + const char *buffer; + int err; + + buffer = get_raw_hash(hash, hash_len, hash_type); + if (IS_ERR(buffer)) + return PTR_ERR(buffer); + err = mark_raw_hash_blacklisted(buffer); + kfree(buffer); + return err; +} + +/** + * is_hash_blacklisted - Determine if a hash is blacklisted + * @hash: The hash to be checked as a binary blob + * @hash_len: The length of the binary hash + * @hash_type: Type of hash + */ +int is_hash_blacklisted(const u8 *hash, size_t hash_len, + enum blacklist_hash_type hash_type) +{ + key_ref_t kref; + const char *buffer; + int ret = 0; + + buffer = get_raw_hash(hash, hash_len, hash_type); + if (IS_ERR(buffer)) + return PTR_ERR(buffer); + kref = keyring_search(make_key_ref(blacklist_keyring, true), + &key_type_blacklist, buffer, false); + if (!IS_ERR(kref)) { + key_ref_put(kref); + ret = -EKEYREJECTED; + } + + kfree(buffer); + return ret; +} +EXPORT_SYMBOL_GPL(is_hash_blacklisted); + +int is_binary_blacklisted(const u8 *hash, size_t hash_len) +{ + if (is_hash_blacklisted(hash, hash_len, BLACKLIST_HASH_BINARY) == + -EKEYREJECTED) + return -EPERM; + + return 0; +} +EXPORT_SYMBOL_GPL(is_binary_blacklisted); + +#ifdef CONFIG_SYSTEM_REVOCATION_LIST +/** + * add_key_to_revocation_list - Add a revocation certificate to the blacklist + * @data: The data blob containing the certificate + * @size: The size of data blob + */ +int add_key_to_revocation_list(const char *data, size_t size) +{ + key_ref_t key; + + key = key_create_or_update(make_key_ref(blacklist_keyring, true), + "asymmetric", + NULL, + data, + size, + KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH + | KEY_USR_VIEW, + KEY_ALLOC_NOT_IN_QUOTA | KEY_ALLOC_BUILT_IN + | KEY_ALLOC_BYPASS_RESTRICTION); + + if (IS_ERR(key)) { + pr_err("Problem with revocation key (%ld)\n", PTR_ERR(key)); + return PTR_ERR(key); + } + + return 0; +} + +/** + * is_key_on_revocation_list - Determine if the key for a PKCS#7 message is revoked + * @pkcs7: The PKCS#7 message to check + */ +int is_key_on_revocation_list(struct pkcs7_message *pkcs7) +{ + int ret; + + ret = pkcs7_validate_trust(pkcs7, blacklist_keyring); + + if (ret == 0) + return -EKEYREJECTED; + + return -ENOKEY; +} +#endif + +static int restrict_link_for_blacklist(struct key *dest_keyring, + const struct key_type *type, const union key_payload *payload, + struct key *restrict_key) +{ + if (type == &key_type_blacklist) + return 0; + return -EOPNOTSUPP; +} + +/* + * Initialise the blacklist + * + * The blacklist_init() function is registered as an initcall via + * device_initcall(). As a result if the blacklist_init() function fails for + * any reason the kernel continues to execute. While cleanly returning -ENODEV + * could be acceptable for some non-critical kernel parts, if the blacklist + * keyring fails to load it defeats the certificate/key based deny list for + * signed modules. If a critical piece of security functionality that users + * expect to be present fails to initialize, panic()ing is likely the right + * thing to do. + */ +static int __init blacklist_init(void) +{ + const char *const *bl; + struct key_restriction *restriction; + + if (register_key_type(&key_type_blacklist) < 0) + panic("Can't allocate system blacklist key type\n"); + + restriction = kzalloc(sizeof(*restriction), GFP_KERNEL); + if (!restriction) + panic("Can't allocate blacklist keyring restriction\n"); + restriction->check = restrict_link_for_blacklist; + + blacklist_keyring = + keyring_alloc(".blacklist", + GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), + KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | + KEY_POS_WRITE | + KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH +#ifdef CONFIG_SYSTEM_BLACKLIST_AUTH_UPDATE + | KEY_USR_WRITE +#endif + , KEY_ALLOC_NOT_IN_QUOTA | + KEY_ALLOC_SET_KEEP, + restriction, NULL); + if (IS_ERR(blacklist_keyring)) + panic("Can't allocate system blacklist keyring\n"); + + for (bl = blacklist_hashes; *bl; bl++) + if (mark_raw_hash_blacklisted(*bl) < 0) + pr_err("- blacklisting failed\n"); + return 0; +} + +/* + * Must be initialised before we try and load the keys into the keyring. + */ +device_initcall(blacklist_init); + +#ifdef CONFIG_SYSTEM_REVOCATION_LIST +/* + * 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 x509_load_certificate_list(revocation_certificate_list, + revocation_certificate_list_size, + blacklist_keyring); +} +late_initcall(load_revocation_certificate_list); +#endif diff --git a/certs/blacklist.h b/certs/blacklist.h new file mode 100644 index 000000000..51b320cf8 --- /dev/null +++ b/certs/blacklist.h @@ -0,0 +1,5 @@ +#include <linux/kernel.h> +#include <linux/errno.h> +#include <crypto/pkcs7.h> + +extern const char __initconst *const blacklist_hashes[]; diff --git a/certs/blacklist_hashes.c b/certs/blacklist_hashes.c new file mode 100644 index 000000000..0c5476abe --- /dev/null +++ b/certs/blacklist_hashes.c @@ -0,0 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "blacklist.h" + +const char __initconst *const blacklist_hashes[] = { +#include "blacklist_hash_list" +}; diff --git a/certs/check-blacklist-hashes.awk b/certs/check-blacklist-hashes.awk new file mode 100755 index 000000000..107c1d320 --- /dev/null +++ b/certs/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@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; + } +} diff --git a/certs/default_x509.genkey b/certs/default_x509.genkey new file mode 100644 index 000000000..d4c6628cb --- /dev/null +++ b/certs/default_x509.genkey @@ -0,0 +1,17 @@ +[ req ] +default_bits = 4096 +distinguished_name = req_distinguished_name +prompt = no +string_mask = utf8only +x509_extensions = myexts + +[ req_distinguished_name ] +#O = Unspecified company +CN = Build time autogenerated kernel key +#emailAddress = unspecified.user@unspecified.company + +[ myexts ] +basicConstraints=critical,CA:FALSE +keyUsage=digitalSignature +subjectKeyIdentifier=hash +authorityKeyIdentifier=keyid diff --git a/certs/extract-cert.c b/certs/extract-cert.c new file mode 100644 index 000000000..8c1fb9a70 --- /dev/null +++ b/certs/extract-cert.c @@ -0,0 +1,169 @@ +/* Extract X.509 certificate in DER form from PKCS#11 or PEM. + * + * Copyright © 2014-2015 Red Hat, Inc. All Rights Reserved. + * Copyright © 2015 Intel Corporation. + * + * Authors: David Howells <dhowells@redhat.com> + * David Woodhouse <dwmw2@infradead.org> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public License + * as published by the Free Software Foundation; either version 2.1 + * of the licence, or (at your option) any later version. + */ +#define _GNU_SOURCE +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <stdbool.h> +#include <string.h> +#include <err.h> +#include <openssl/bio.h> +#include <openssl/pem.h> +#include <openssl/err.h> +#include <openssl/engine.h> + +/* + * OpenSSL 3.0 deprecates the OpenSSL's ENGINE API. + * + * Remove this if/when that API is no longer used + */ +#pragma GCC diagnostic ignored "-Wdeprecated-declarations" + +#define PKEY_ID_PKCS7 2 + +static __attribute__((noreturn)) +void format(void) +{ + fprintf(stderr, + "Usage: extract-cert <source> <dest>\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; +static BIO *wb; +static char *cert_dst; +static int kbuild_verbose; + +static void write_cert(X509 *x509) +{ + char buf[200]; + + if (!wb) { + wb = BIO_new_file(cert_dst, "wb"); + ERR(!wb, "%s", cert_dst); + } + X509_NAME_oneline(X509_get_subject_name(x509), buf, sizeof(buf)); + ERR(!i2d_X509_bio(wb, x509), "%s", cert_dst); + if (kbuild_verbose) + fprintf(stderr, "Extracted cert: %s\n", buf); +} + +int main(int argc, char **argv) +{ + char *cert_src; + + OpenSSL_add_all_algorithms(); + ERR_load_crypto_strings(); + ERR_clear_error(); + + kbuild_verbose = atoi(getenv("KBUILD_VERBOSE")?:"0"); + + key_pass = getenv("KBUILD_SIGN_PIN"); + + if (argc != 3) + format(); + + cert_src = argv[1]; + cert_dst = argv[2]; + + if (!cert_src[0]) { + /* Invoked with no input; create empty file */ + FILE *f = fopen(cert_dst, "wb"); + ERR(!f, "%s", cert_dst); + fclose(f); + exit(0); + } else 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"); + write_cert(parms.cert); + } else { + BIO *b; + X509 *x509; + + b = BIO_new_file(cert_src, "rb"); + ERR(!b, "%s", cert_src); + + while (1) { + x509 = PEM_read_bio_X509(b, NULL, NULL, NULL); + if (wb && !x509) { + unsigned long err = ERR_peek_last_error(); + if (ERR_GET_LIB(err) == ERR_LIB_PEM && + ERR_GET_REASON(err) == PEM_R_NO_START_LINE) { + ERR_clear_error(); + break; + } + } + ERR(!x509, "%s", cert_src); + write_cert(x509); + } + } + + BIO_free(wb); + + return 0; +} diff --git a/certs/revocation_certificates.S b/certs/revocation_certificates.S new file mode 100644 index 000000000..f21aae8a8 --- /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/certs/system_certificates.S b/certs/system_certificates.S new file mode 100644 index 000000000..003e25d4a --- /dev/null +++ b/certs/system_certificates.S @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <linux/export.h> +#include <linux/init.h> + + __INITRODATA + + .align 8 + .globl system_certificate_list +system_certificate_list: +__cert_list_start: +__module_cert_start: + .incbin "certs/signing_key.x509" +__module_cert_end: + .incbin "certs/x509_certificate_list" +__cert_list_end: + +#ifdef CONFIG_SYSTEM_EXTRA_CERTIFICATE + .globl system_extra_cert + .size system_extra_cert, CONFIG_SYSTEM_EXTRA_CERTIFICATE_SIZE +system_extra_cert: + .fill CONFIG_SYSTEM_EXTRA_CERTIFICATE_SIZE, 1, 0 + + .align 4 + .globl system_extra_cert_used +system_extra_cert_used: + .int 0 + +#endif /* CONFIG_SYSTEM_EXTRA_CERTIFICATE */ + + .align 8 + .globl system_certificate_list_size +system_certificate_list_size: +#ifdef CONFIG_64BIT + .quad __cert_list_end - __cert_list_start +#else + .long __cert_list_end - __cert_list_start +#endif + + .align 8 + .globl module_cert_size +module_cert_size: +#ifdef CONFIG_64BIT + .quad __module_cert_end - __module_cert_start +#else + .long __module_cert_end - __module_cert_start +#endif diff --git a/certs/system_keyring.c b/certs/system_keyring.c new file mode 100644 index 000000000..5042cc54f --- /dev/null +++ b/certs/system_keyring.c @@ -0,0 +1,341 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* System trusted keyring for trusted public keys + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/cred.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/uidgid.h> +#include <linux/verification.h> +#include <keys/asymmetric-type.h> +#include <keys/system_keyring.h> +#include <crypto/pkcs7.h> + +static struct key *builtin_trusted_keys; +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING +static struct key *secondary_trusted_keys; +#endif +#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING +static struct key *machine_trusted_keys; +#endif +#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING +static struct key *platform_trusted_keys; +#endif + +extern __initconst const u8 system_certificate_list[]; +extern __initconst const unsigned long system_certificate_list_size; +extern __initconst const unsigned long module_cert_size; + +/** + * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA + * + * Restrict the addition of keys into a keyring based on the key-to-be-added + * being vouched for by a key in the built in system keyring. + */ +int restrict_link_by_builtin_trusted(struct key *dest_keyring, + const struct key_type *type, + const union key_payload *payload, + struct key *restriction_key) +{ + return restrict_link_by_signature(dest_keyring, type, payload, + builtin_trusted_keys); +} + +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING +/** + * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring + * addition by both builtin and secondary keyrings + * + * Restrict the addition of keys into a keyring based on the key-to-be-added + * being vouched for by a key in either the built-in or the secondary system + * keyrings. + */ +int restrict_link_by_builtin_and_secondary_trusted( + struct key *dest_keyring, + const struct key_type *type, + const union key_payload *payload, + struct key *restrict_key) +{ + /* If we have a secondary trusted keyring, then that contains a link + * through to the builtin keyring and the search will follow that link. + */ + if (type == &key_type_keyring && + dest_keyring == secondary_trusted_keys && + payload == &builtin_trusted_keys->payload) + /* Allow the builtin keyring to be added to the secondary */ + return 0; + + return restrict_link_by_signature(dest_keyring, type, payload, + secondary_trusted_keys); +} + +/** + * Allocate a struct key_restriction for the "builtin and secondary trust" + * keyring. Only for use in system_trusted_keyring_init(). + */ +static __init struct key_restriction *get_builtin_and_secondary_restriction(void) +{ + struct key_restriction *restriction; + + restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL); + + if (!restriction) + panic("Can't allocate secondary trusted keyring restriction\n"); + + if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING)) + restriction->check = restrict_link_by_builtin_secondary_and_machine; + else + restriction->check = restrict_link_by_builtin_and_secondary_trusted; + + return restriction; +} +#endif +#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING +void __init set_machine_trusted_keys(struct key *keyring) +{ + machine_trusted_keys = keyring; + + if (key_link(secondary_trusted_keys, machine_trusted_keys) < 0) + panic("Can't link (machine) trusted keyrings\n"); +} + +/** + * restrict_link_by_builtin_secondary_and_machine - Restrict keyring addition. + * @dest_keyring: Keyring being linked to. + * @type: The type of key being added. + * @payload: The payload of the new key. + * @restrict_key: A ring of keys that can be used to vouch for the new cert. + * + * Restrict the addition of keys into a keyring based on the key-to-be-added + * being vouched for by a key in either the built-in, the secondary, or + * the machine keyrings. + */ +int restrict_link_by_builtin_secondary_and_machine( + struct key *dest_keyring, + const struct key_type *type, + const union key_payload *payload, + struct key *restrict_key) +{ + if (machine_trusted_keys && type == &key_type_keyring && + dest_keyring == secondary_trusted_keys && + payload == &machine_trusted_keys->payload) + /* Allow the machine keyring to be added to the secondary */ + return 0; + + return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type, + payload, restrict_key); +} +#endif + +/* + * Create the trusted keyrings + */ +static __init int system_trusted_keyring_init(void) +{ + pr_notice("Initialise system trusted keyrings\n"); + + builtin_trusted_keys = + keyring_alloc(".builtin_trusted_keys", + GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), + ((KEY_POS_ALL & ~KEY_POS_SETATTR) | + KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), + KEY_ALLOC_NOT_IN_QUOTA, + NULL, NULL); + if (IS_ERR(builtin_trusted_keys)) + panic("Can't allocate builtin trusted keyring\n"); + +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING + secondary_trusted_keys = + keyring_alloc(".secondary_trusted_keys", + GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), + ((KEY_POS_ALL & ~KEY_POS_SETATTR) | + KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | + KEY_USR_WRITE), + KEY_ALLOC_NOT_IN_QUOTA, + get_builtin_and_secondary_restriction(), + NULL); + if (IS_ERR(secondary_trusted_keys)) + panic("Can't allocate secondary trusted keyring\n"); + + if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) + panic("Can't link trusted keyrings\n"); +#endif + + return 0; +} + +/* + * Must be initialised before we try and load the keys into the keyring. + */ +device_initcall(system_trusted_keyring_init); + +__init int load_module_cert(struct key *keyring) +{ + if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG)) + return 0; + + pr_notice("Loading compiled-in module X.509 certificates\n"); + + return x509_load_certificate_list(system_certificate_list, + module_cert_size, keyring); +} + +/* + * Load the compiled-in list of X.509 certificates. + */ +static __init int load_system_certificate_list(void) +{ + const u8 *p; + unsigned long size; + + pr_notice("Loading compiled-in X.509 certificates\n"); + +#ifdef CONFIG_MODULE_SIG + p = system_certificate_list; + size = system_certificate_list_size; +#else + p = system_certificate_list + module_cert_size; + size = system_certificate_list_size - module_cert_size; +#endif + + return x509_load_certificate_list(p, size, builtin_trusted_keys); +} +late_initcall(load_system_certificate_list); + +#ifdef CONFIG_SYSTEM_DATA_VERIFICATION + +/** + * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data. + * @data: The data to be verified (NULL if expecting internal data). + * @len: Size of @data. + * @pkcs7: The PKCS#7 message that is the signature. + * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, + * (void *)1UL for all trusted keys). + * @usage: The use to which the key is being put. + * @view_content: Callback to gain access to content. + * @ctx: Context for callback. + */ +int verify_pkcs7_message_sig(const void *data, size_t len, + struct pkcs7_message *pkcs7, + struct key *trusted_keys, + enum key_being_used_for usage, + int (*view_content)(void *ctx, + const void *data, size_t len, + size_t asn1hdrlen), + void *ctx) +{ + int ret; + + /* The data should be detached - so we need to supply it. */ + if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { + pr_err("PKCS#7 signature with non-detached data\n"); + ret = -EBADMSG; + goto error; + } + + ret = pkcs7_verify(pkcs7, usage); + if (ret < 0) + goto error; + + if (!trusted_keys) { + trusted_keys = builtin_trusted_keys; + } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING + trusted_keys = secondary_trusted_keys; +#else + trusted_keys = builtin_trusted_keys; +#endif + } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { +#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING + trusted_keys = platform_trusted_keys; +#else + trusted_keys = NULL; +#endif + if (!trusted_keys) { + ret = -ENOKEY; + pr_devel("PKCS#7 platform keyring is not available\n"); + goto error; + } + + ret = is_key_on_revocation_list(pkcs7); + if (ret != -ENOKEY) { + pr_devel("PKCS#7 platform key is on revocation list\n"); + goto error; + } + } + ret = pkcs7_validate_trust(pkcs7, trusted_keys); + if (ret < 0) { + if (ret == -ENOKEY) + pr_devel("PKCS#7 signature not signed with a trusted key\n"); + goto error; + } + + if (view_content) { + size_t asn1hdrlen; + + ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); + if (ret < 0) { + if (ret == -ENODATA) + pr_devel("PKCS#7 message does not contain data\n"); + goto error; + } + + ret = view_content(ctx, data, len, asn1hdrlen); + } + +error: + pr_devel("<==%s() = %d\n", __func__, ret); + return ret; +} + +/** + * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. + * @data: The data to be verified (NULL if expecting internal data). + * @len: Size of @data. + * @raw_pkcs7: The PKCS#7 message that is the signature. + * @pkcs7_len: The size of @raw_pkcs7. + * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, + * (void *)1UL for all trusted keys). + * @usage: The use to which the key is being put. + * @view_content: Callback to gain access to content. + * @ctx: Context for callback. + */ +int verify_pkcs7_signature(const void *data, size_t len, + const void *raw_pkcs7, size_t pkcs7_len, + struct key *trusted_keys, + enum key_being_used_for usage, + int (*view_content)(void *ctx, + const void *data, size_t len, + size_t asn1hdrlen), + void *ctx) +{ + struct pkcs7_message *pkcs7; + int ret; + + pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); + if (IS_ERR(pkcs7)) + return PTR_ERR(pkcs7); + + ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage, + view_content, ctx); + + pkcs7_free_message(pkcs7); + pr_devel("<==%s() = %d\n", __func__, ret); + return ret; +} +EXPORT_SYMBOL_GPL(verify_pkcs7_signature); + +#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ + +#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING +void __init set_platform_trusted_keys(struct key *keyring) +{ + platform_trusted_keys = keyring; +} +#endif |