KEYS: Add a system blacklist keyring

	  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> should

	  be a string of hex digits.

endmenu

#

obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o

obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist.o

ifneq ($(CONFIG_SYSTEM_BLACKLIST_HASH_LIST),"")

obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_hashes.o

else

obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_nohashes.o

endif

ifeq ($(CONFIG_SYSTEM_TRUSTED_KEYRING),y)

/* System hash blacklist.

 *

 * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.

 * Written by David Howells (dhowells@redhat.com)

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public Licence

 * as published by the Free Software Foundation; either version

 * 2 of the Licence, or (at your option) any later version.

 */

#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 <keys/system_keyring.h>

#include "blacklist.h"

static struct key *blacklist_keyring;

/*

 * 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 n = 0;

	if (*desc == ':')

		return -EINVAL;

	for (; *desc; desc++)

		if (*desc == ':')

			goto found_colon;

	return -EINVAL;

found_colon:

	desc++;

	for (; *desc; desc++) {

		if (!isxdigit(*desc))

			return -EINVAL;

		n++;

	}

	if (n == 0 || n & 1)

		return -EINVAL;

	return 0;

}

/*

 * The hash to be blacklisted is expected to be in the description.  There will

 * be no payload.

 */

static int blacklist_preparse(struct key_preparsed_payload *prep)

{

	if (prep->datalen > 0)

		return -EINVAL;

	return 0;

}

static void blacklist_free_preparse(struct key_preparsed_payload *prep)

{

}

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,

	.preparse		= blacklist_preparse,

	.free_preparse		= blacklist_free_preparse,

	.instantiate		= generic_key_instantiate,

	.describe		= blacklist_describe,

};

/**

 * mark_hash_blacklisted - Add a hash to the system blacklist

 * @hash - The hash as a hex string with a type prefix (eg. "tbs:23aa429783")

 */

int mark_hash_blacklisted(const char *hash)

{

	key_ref_t key;

	key = key_create_or_update(make_key_ref(blacklist_keyring, true),

				   "blacklist",

				   hash,

				   NULL,

				   0,

				   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |

				    KEY_USR_VIEW),

				   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;

}

/**

 * 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

 * @type: Type of hash

 */

int is_hash_blacklisted(const u8 *hash, size_t hash_len, const char *type)

{

	key_ref_t kref;

	size_t type_len = strlen(type);

	char *buffer, *p;

	int ret = 0;

	buffer = kmalloc(type_len + 1 + hash_len * 2 + 1, GFP_KERNEL);

	if (!buffer)

		return -ENOMEM;

	p = memcpy(buffer, type, type_len);

	p += type_len;

	*p++ = ':';

	bin2hex(p, hash, hash_len);

	p += hash_len * 2;

	*p = 0;

	kref = keyring_search(make_key_ref(blacklist_keyring, true),

			      &key_type_blacklist, buffer);

	if (!IS_ERR(kref)) {

		key_ref_put(kref);

		ret = -EKEYREJECTED;

	}

	kfree(buffer);

	return ret;

}

EXPORT_SYMBOL_GPL(is_hash_blacklisted);

/*

 * Intialise the blacklist

 */

static int __init blacklist_init(void)

{

	const char *const *bl;

	if (register_key_type(&key_type_blacklist) < 0)

		panic("Can't allocate system blacklist key type\n");

	blacklist_keyring =

		keyring_alloc(".blacklist",

			      KUIDT_INIT(0), KGIDT_INIT(0),

			      current_cred(),

			      (KEY_POS_ALL & ~KEY_POS_SETATTR) |

			      KEY_USR_VIEW | KEY_USR_READ |

			      KEY_USR_SEARCH,

			      KEY_ALLOC_NOT_IN_QUOTA |

			      KEY_FLAG_KEEP,

			      NULL, NULL);

	if (IS_ERR(blacklist_keyring))

		panic("Can't allocate system blacklist keyring\n");

	for (bl = blacklist_hashes; *bl; bl++)

		if (mark_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);

#include <linux/kernel.h>

extern const char __initdata *const blacklist_hashes[];

#include "blacklist.h"

const char __initdata *const blacklist_hashes[] = {

#include CONFIG_SYSTEM_BLACKLIST_HASH_LIST

	, NULL

};