| // 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_by_builtin_trusted - Restrict keyring addition by built-in CA |
| * @dest_keyring: Keyring being linked to. |
| * @type: The type of key being added. |
| * @payload: The payload of the new key. |
| * @restriction_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 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 built-in and secondary keyrings. |
| * @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 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 |