linux/certs/blacklist.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* System hash blacklist.
 *
 * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 */

#define pr_fmt(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 …

#define BLACKLIST_KEY_PERM …

static const char tbs_prefix[] = …;
static const char bin_prefix[] = …;

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)
{ … }

static int blacklist_key_instantiate(struct key *key,
		struct key_preparsed_payload *prep)
{ … }

static int blacklist_key_update(struct key *key,
		struct key_preparsed_payload *prep)
{ … }

static void blacklist_describe(const struct key *key, struct seq_file *m)
{ … }

static struct key_type key_type_blacklist = …;

static char *get_raw_hash(const u8 *hash, size_t hash_len,
		enum blacklist_hash_type hash_type)
{ … }

/**
 * 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)
{ … }

int mark_hash_blacklisted(const u8 *hash, size_t hash_len,
		enum blacklist_hash_type hash_type)
{ … }

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

int is_binary_blacklisted(const u8 *hash, size_t hash_len)
{ … }
EXPORT_SYMBOL_GPL(…);

#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)
{ … }

/**
 * 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)
{ … }
#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)
{ … }

/*
 * 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)
{ … }

/*
 * 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)
{ … }
late_initcall(load_revocation_certificate_list);
#endif