350 lines
10 KiB
C
350 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* System trusted keyring for trusted public keys
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*
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* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/cred.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/uidgid.h>
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#include <linux/verification.h>
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#include <keys/asymmetric-type.h>
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#include <keys/system_keyring.h>
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#include <crypto/pkcs7.h>
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static struct key *builtin_trusted_keys;
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#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
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static struct key *secondary_trusted_keys;
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#endif
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#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
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static struct key *machine_trusted_keys;
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#endif
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#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
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static struct key *platform_trusted_keys;
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#endif
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extern __initconst const u8 system_certificate_list[];
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extern __initconst const unsigned long system_certificate_list_size;
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extern __initconst const unsigned long module_cert_size;
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/**
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* restrict_link_by_builtin_trusted - Restrict keyring addition by built-in CA
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* @dest_keyring: Keyring being linked to.
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* @type: The type of key being added.
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* @payload: The payload of the new key.
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* @restriction_key: A ring of keys that can be used to vouch for the new cert.
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*
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* Restrict the addition of keys into a keyring based on the key-to-be-added
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* being vouched for by a key in the built in system keyring.
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*/
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int restrict_link_by_builtin_trusted(struct key *dest_keyring,
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const struct key_type *type,
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const union key_payload *payload,
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struct key *restriction_key)
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{
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return restrict_link_by_signature(dest_keyring, type, payload,
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builtin_trusted_keys);
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}
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#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
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/**
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* restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
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* addition by both built-in and secondary keyrings.
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* @dest_keyring: Keyring being linked to.
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* @type: The type of key being added.
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* @payload: The payload of the new key.
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* @restrict_key: A ring of keys that can be used to vouch for the new cert.
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*
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* Restrict the addition of keys into a keyring based on the key-to-be-added
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* being vouched for by a key in either the built-in or the secondary system
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* keyrings.
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*/
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int restrict_link_by_builtin_and_secondary_trusted(
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struct key *dest_keyring,
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const struct key_type *type,
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const union key_payload *payload,
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struct key *restrict_key)
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{
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/* If we have a secondary trusted keyring, then that contains a link
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* through to the builtin keyring and the search will follow that link.
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*/
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if (type == &key_type_keyring &&
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dest_keyring == secondary_trusted_keys &&
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payload == &builtin_trusted_keys->payload)
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/* Allow the builtin keyring to be added to the secondary */
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return 0;
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return restrict_link_by_signature(dest_keyring, type, payload,
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secondary_trusted_keys);
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}
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/*
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* Allocate a struct key_restriction for the "builtin and secondary trust"
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* keyring. Only for use in system_trusted_keyring_init().
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*/
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static __init struct key_restriction *get_builtin_and_secondary_restriction(void)
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{
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struct key_restriction *restriction;
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restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
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if (!restriction)
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panic("Can't allocate secondary trusted keyring restriction\n");
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if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING))
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restriction->check = restrict_link_by_builtin_secondary_and_machine;
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else
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restriction->check = restrict_link_by_builtin_and_secondary_trusted;
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return restriction;
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}
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#endif
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#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
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void __init set_machine_trusted_keys(struct key *keyring)
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{
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machine_trusted_keys = keyring;
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if (key_link(secondary_trusted_keys, machine_trusted_keys) < 0)
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panic("Can't link (machine) trusted keyrings\n");
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}
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/**
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* restrict_link_by_builtin_secondary_and_machine - Restrict keyring addition.
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* @dest_keyring: Keyring being linked to.
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* @type: The type of key being added.
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* @payload: The payload of the new key.
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* @restrict_key: A ring of keys that can be used to vouch for the new cert.
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*
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* Restrict the addition of keys into a keyring based on the key-to-be-added
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* being vouched for by a key in either the built-in, the secondary, or
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* the machine keyrings.
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*/
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int restrict_link_by_builtin_secondary_and_machine(
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struct key *dest_keyring,
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const struct key_type *type,
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const union key_payload *payload,
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struct key *restrict_key)
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{
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if (machine_trusted_keys && type == &key_type_keyring &&
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dest_keyring == secondary_trusted_keys &&
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payload == &machine_trusted_keys->payload)
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/* Allow the machine keyring to be added to the secondary */
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return 0;
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return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type,
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payload, restrict_key);
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}
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#endif
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/*
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* Create the trusted keyrings
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*/
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static __init int system_trusted_keyring_init(void)
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{
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pr_notice("Initialise system trusted keyrings\n");
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builtin_trusted_keys =
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keyring_alloc(".builtin_trusted_keys",
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GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(),
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((KEY_POS_ALL & ~KEY_POS_SETATTR) |
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KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
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KEY_ALLOC_NOT_IN_QUOTA,
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NULL, NULL);
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if (IS_ERR(builtin_trusted_keys))
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panic("Can't allocate builtin trusted keyring\n");
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#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
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secondary_trusted_keys =
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keyring_alloc(".secondary_trusted_keys",
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GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(),
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((KEY_POS_ALL & ~KEY_POS_SETATTR) |
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KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH |
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KEY_USR_WRITE),
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KEY_ALLOC_NOT_IN_QUOTA,
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get_builtin_and_secondary_restriction(),
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NULL);
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if (IS_ERR(secondary_trusted_keys))
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panic("Can't allocate secondary trusted keyring\n");
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if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)
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panic("Can't link trusted keyrings\n");
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#endif
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return 0;
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}
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/*
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* Must be initialised before we try and load the keys into the keyring.
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*/
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device_initcall(system_trusted_keyring_init);
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__init int load_module_cert(struct key *keyring)
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{
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if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG))
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return 0;
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pr_notice("Loading compiled-in module X.509 certificates\n");
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return x509_load_certificate_list(system_certificate_list,
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module_cert_size, keyring);
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}
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/*
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* Load the compiled-in list of X.509 certificates.
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*/
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static __init int load_system_certificate_list(void)
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{
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const u8 *p;
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unsigned long size;
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pr_notice("Loading compiled-in X.509 certificates\n");
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#ifdef CONFIG_MODULE_SIG
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p = system_certificate_list;
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size = system_certificate_list_size;
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#else
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p = system_certificate_list + module_cert_size;
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size = system_certificate_list_size - module_cert_size;
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#endif
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return x509_load_certificate_list(p, size, builtin_trusted_keys);
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}
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late_initcall(load_system_certificate_list);
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#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
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/**
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* verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data.
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* @data: The data to be verified (NULL if expecting internal data).
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* @len: Size of @data.
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* @pkcs7: The PKCS#7 message that is the signature.
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* @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
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* (void *)1UL for all trusted keys).
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* @usage: The use to which the key is being put.
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* @view_content: Callback to gain access to content.
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* @ctx: Context for callback.
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*/
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int verify_pkcs7_message_sig(const void *data, size_t len,
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struct pkcs7_message *pkcs7,
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struct key *trusted_keys,
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enum key_being_used_for usage,
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int (*view_content)(void *ctx,
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const void *data, size_t len,
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size_t asn1hdrlen),
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void *ctx)
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{
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int ret;
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/* The data should be detached - so we need to supply it. */
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if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
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pr_err("PKCS#7 signature with non-detached data\n");
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ret = -EBADMSG;
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goto error;
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}
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ret = pkcs7_verify(pkcs7, usage);
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if (ret < 0)
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goto error;
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if (!trusted_keys) {
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trusted_keys = builtin_trusted_keys;
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} else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) {
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#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
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trusted_keys = secondary_trusted_keys;
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#else
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trusted_keys = builtin_trusted_keys;
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#endif
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} else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) {
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#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
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trusted_keys = platform_trusted_keys;
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#else
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trusted_keys = NULL;
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#endif
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if (!trusted_keys) {
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ret = -ENOKEY;
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pr_devel("PKCS#7 platform keyring is not available\n");
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goto error;
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}
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ret = is_key_on_revocation_list(pkcs7);
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if (ret != -ENOKEY) {
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pr_devel("PKCS#7 platform key is on revocation list\n");
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goto error;
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}
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}
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ret = pkcs7_validate_trust(pkcs7, trusted_keys);
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if (ret < 0) {
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if (ret == -ENOKEY)
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pr_devel("PKCS#7 signature not signed with a trusted key\n");
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goto error;
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}
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if (view_content) {
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size_t asn1hdrlen;
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ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
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if (ret < 0) {
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if (ret == -ENODATA)
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pr_devel("PKCS#7 message does not contain data\n");
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goto error;
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}
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ret = view_content(ctx, data, len, asn1hdrlen);
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}
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error:
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pr_devel("<==%s() = %d\n", __func__, ret);
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return ret;
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}
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/**
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* verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
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* @data: The data to be verified (NULL if expecting internal data).
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* @len: Size of @data.
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* @raw_pkcs7: The PKCS#7 message that is the signature.
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* @pkcs7_len: The size of @raw_pkcs7.
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* @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
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* (void *)1UL for all trusted keys).
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* @usage: The use to which the key is being put.
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* @view_content: Callback to gain access to content.
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* @ctx: Context for callback.
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*/
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int verify_pkcs7_signature(const void *data, size_t len,
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const void *raw_pkcs7, size_t pkcs7_len,
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struct key *trusted_keys,
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enum key_being_used_for usage,
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int (*view_content)(void *ctx,
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const void *data, size_t len,
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size_t asn1hdrlen),
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void *ctx)
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{
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struct pkcs7_message *pkcs7;
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int ret;
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pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
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if (IS_ERR(pkcs7))
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return PTR_ERR(pkcs7);
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ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage,
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view_content, ctx);
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pkcs7_free_message(pkcs7);
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pr_devel("<==%s() = %d\n", __func__, ret);
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return ret;
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}
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EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
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#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
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#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
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void __init set_platform_trusted_keys(struct key *keyring)
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{
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platform_trusted_keys = keyring;
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}
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#endif
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