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Diffstat (limited to '')
| -rw-r--r-- | certs/system_keyring.c | 341 |
1 files changed, 341 insertions, 0 deletions
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 |