[mirror_ubuntu-bionic-kernel.git] / certs / system_keyring.c

/* System trusted keyring for trusted public keys
 *
 * Copyright (C) 2012 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.
 */

#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/verification.h>
#include <keys/asymmetric-type.h>
#include <keys/system_keyring.h>
#include <crypto/pkcs7.h>
#include "internal.h"

static struct key *builtin_trusted_keys;
#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
static struct key *secondary_trusted_keys;
#endif

extern __initconst const u8 system_certificate_list[];
extern __initconst const unsigned long system_certificate_list_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");

	restriction->check = restrict_link_by_builtin_and_secondary_trusted;

	return restriction;
}
#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",
			      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,
			      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",
			      KUIDT_INIT(0), KGIDT_INIT(0), 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);

/*
 * Load the compiled-in list of X.509 certificates.
 */
static __init int load_system_certificate_list(void)
{
	key_ref_t key;
	const u8 *p, *end;
	size_t plen;

	pr_notice("Loading compiled-in X.509 certificates\n");

	p = system_certificate_list;
	end = p + system_certificate_list_size;
	while (p < end) {
		/* Each cert begins with an ASN.1 SEQUENCE tag and must be more
		 * than 256 bytes in size.
		 */
		if (end - p < 4)
			goto dodgy_cert;
		if (p[0] != 0x30 &&
		    p[1] != 0x82)
			goto dodgy_cert;
		plen = (p[2] << 8) | p[3];
		plen += 4;
		if (plen > end - p)
			goto dodgy_cert;

		key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1),
					   "asymmetric",
					   NULL,
					   p,
					   plen,
					   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
					   KEY_USR_VIEW | KEY_USR_READ),
					   KEY_ALLOC_NOT_IN_QUOTA |
					   KEY_ALLOC_BUILT_IN |
					   KEY_ALLOC_BYPASS_RESTRICTION);
		if (IS_ERR(key)) {
			pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
			       PTR_ERR(key));
			WARN_ON_ONCE(1);
		} else {
			pr_notice("Loaded X.509 cert '%s'\n",
				  key_ref_to_ptr(key)->description);
			key_ref_put(key);
		}
		p += plen;
	}

	return 0;

dodgy_cert:
	pr_err("Problem parsing in-kernel X.509 certificate list\n");
	return 0;
}
late_initcall(load_system_certificate_list);

#ifdef CONFIG_SYSTEM_DATA_VERIFICATION

/**
 * 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);

	/* 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
	}
	ret = pkcs7_validate_trust(pkcs7, trusted_keys);
	if (ret < 0) {
		if (ret == -ENOKEY)
			pr_err("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:
	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_SECONDARY_TRUSTED_KEYRING
/**
 * add_trusted_secondary_key - Add to secondary keyring with no validation
 * @source: Source of key
 * @data: The blob holding the key
 * @len: The length of the data blob
 *
 * Add a key to the secondary keyring without checking its trust chain.  This
 * is available only during kernel initialisation.
 */
void __init add_trusted_secondary_key(const char *source,
				      const void *data, size_t len)
{
	key_ref_t key;

	key = key_create_or_update(make_key_ref(secondary_trusted_keys, 1),
				   "asymmetric",
				   NULL, data, len,
				   (KEY_POS_ALL & ~KEY_POS_SETATTR) |
				   KEY_USR_VIEW,
				   KEY_ALLOC_NOT_IN_QUOTA |
				   KEY_ALLOC_BYPASS_RESTRICTION);

	if (IS_ERR(key))
		pr_err("Problem loading %s X.509 certificate (%ld)\n",
		       source, PTR_ERR(key));
	else
		pr_notice("Loaded %s cert '%s' linked to secondary sys keyring\n",
			  source, key_ref_to_ptr(key)->description);
}
#endif /* CONFIG_SECONDARY_TRUSTED_KEYRING */
Commit	Line	Data
b56e5a17 DH	1	/* System trusted keyring for trusted public keys
	2	*
	3	* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public Licence
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the Licence, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/export.h>
	13	#include <linux/kernel.h>
	14	#include <linux/sched.h>
	15	#include <linux/cred.h>
	16	#include <linux/err.h>
2b6aa412	17	#include <linux/slab.h>
c23268ec	18	#include <linux/verification.h>
b56e5a17 DH	19	#include <keys/asymmetric-type.h>
b56e5a17 DH	20	#include <keys/system_keyring.h>
091f6e26	21	#include <crypto/pkcs7.h>
373b0cb1	22	#include "internal.h"
b56e5a17	23
d3bfe841 DH	24	static struct key *builtin_trusted_keys;
	25	#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
	26	static struct key *secondary_trusted_keys;
	27	#endif
b56e5a17 DH	28
b56e5a17 DH	29	extern __initconst const u8 system_certificate_list[];
62226983	30	extern __initconst const unsigned long system_certificate_list_size;
b56e5a17	31
a511e1af	32	/**
d3bfe841	33	* restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
a511e1af DH	34	*
a511e1af DH	35	* Restrict the addition of keys into a keyring based on the key-to-be-added
d3bfe841	36	* being vouched for by a key in the built in system keyring.
a511e1af	37	*/
aaf66c88	38	int restrict_link_by_builtin_trusted(struct key *dest_keyring,
a511e1af	39	const struct key_type *type,
aaf66c88 MM	40	const union key_payload *payload,
aaf66c88 MM	41	struct key *restriction_key)
a511e1af	42	{
aaf66c88 MM	43	return restrict_link_by_signature(dest_keyring, type, payload,
aaf66c88 MM	44	builtin_trusted_keys);
a511e1af DH	45	}
a511e1af DH	46
d3bfe841 DH	47	#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
	48	/**
	49	* restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
	50	* addition by both builtin and secondary keyrings
	51	*
	52	* Restrict the addition of keys into a keyring based on the key-to-be-added
	53	* being vouched for by a key in either the built-in or the secondary system
	54	* keyrings.
	55	*/
	56	int restrict_link_by_builtin_and_secondary_trusted(
aaf66c88	57	struct key *dest_keyring,
d3bfe841	58	const struct key_type *type,
aaf66c88 MM	59	const union key_payload *payload,
aaf66c88 MM	60	struct key *restrict_key)
d3bfe841 DH	61	{
	62	/* If we have a secondary trusted keyring, then that contains a link
	63	* through to the builtin keyring and the search will follow that link.
	64	*/
	65	if (type == &key_type_keyring &&
aaf66c88	66	dest_keyring == secondary_trusted_keys &&
d3bfe841 DH	67	payload == &builtin_trusted_keys->payload)
	68	/* Allow the builtin keyring to be added to the secondary */
	69	return 0;
	70
aaf66c88 MM	71	return restrict_link_by_signature(dest_keyring, type, payload,
aaf66c88 MM	72	secondary_trusted_keys);
d3bfe841	73	}
2b6aa412 MM	74
	75	/**
	76	* Allocate a struct key_restriction for the "builtin and secondary trust"
	77	* keyring. Only for use in system_trusted_keyring_init().
	78	*/
	79	static __init struct key_restriction *get_builtin_and_secondary_restriction(void)
	80	{
	81	struct key_restriction *restriction;
	82
	83	restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
	84
	85	if (!restriction)
	86	panic("Can't allocate secondary trusted keyring restriction\n");
	87
	88	restriction->check = restrict_link_by_builtin_and_secondary_trusted;
	89
	90	return restriction;
	91	}
d3bfe841 DH	92	#endif
d3bfe841 DH	93
b56e5a17	94	/*
d3bfe841	95	* Create the trusted keyrings
b56e5a17 DH	96	*/
	97	static __init int system_trusted_keyring_init(void)
	98	{
d3bfe841	99	pr_notice("Initialise system trusted keyrings\n");
b56e5a17	100
d3bfe841 DH	101	builtin_trusted_keys =
d3bfe841 DH	102	keyring_alloc(".builtin_trusted_keys",
b56e5a17 DH	103	KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
b56e5a17 DH	104	((KEY_POS_ALL & ~KEY_POS_SETATTR) \|
af34cb0c	105	KEY_USR_VIEW \| KEY_USR_READ \| KEY_USR_SEARCH),
5ac7eace	106	KEY_ALLOC_NOT_IN_QUOTA,
d3bfe841 DH	107	NULL, NULL);
	108	if (IS_ERR(builtin_trusted_keys))
	109	panic("Can't allocate builtin trusted keyring\n");
	110
	111	#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
	112	secondary_trusted_keys =
	113	keyring_alloc(".secondary_trusted_keys",
	114	KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
	115	((KEY_POS_ALL & ~KEY_POS_SETATTR) \|
	116	KEY_USR_VIEW \| KEY_USR_READ \| KEY_USR_SEARCH \|
	117	KEY_USR_WRITE),
	118	KEY_ALLOC_NOT_IN_QUOTA,
2b6aa412	119	get_builtin_and_secondary_restriction(),
d3bfe841 DH	120	NULL);
	121	if (IS_ERR(secondary_trusted_keys))
	122	panic("Can't allocate secondary trusted keyring\n");
	123
	124	if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)
	125	panic("Can't link trusted keyrings\n");
	126	#endif
	127
b56e5a17 DH	128	return 0;
	129	}
	130
	131	/*
	132	* Must be initialised before we try and load the keys into the keyring.
	133	*/
	134	device_initcall(system_trusted_keyring_init);
	135
	136	/*
	137	* Load the compiled-in list of X.509 certificates.
	138	*/
	139	static __init int load_system_certificate_list(void)
	140	{
	141	key_ref_t key;
	142	const u8 p, end;
	143	size_t plen;
	144
	145	pr_notice("Loading compiled-in X.509 certificates\n");
	146
b56e5a17	147	p = system_certificate_list;
62226983	148	end = p + system_certificate_list_size;
b56e5a17 DH	149	while (p < end) {
	150	/* Each cert begins with an ASN.1 SEQUENCE tag and must be more
	151	* than 256 bytes in size.
	152	*/
	153	if (end - p < 4)
	154	goto dodgy_cert;
	155	if (p[0] != 0x30 &&
	156	p[1] != 0x82)
	157	goto dodgy_cert;
	158	plen = (p[2] << 8) \| p[3];
	159	plen += 4;
	160	if (plen > end - p)
	161	goto dodgy_cert;
	162
d3bfe841	163	key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1),
b56e5a17 DH	164	"asymmetric",
	165	NULL,
	166	p,
	167	plen,
af34cb0c MZ	168	((KEY_POS_ALL & ~KEY_POS_SETATTR) \|
af34cb0c MZ	169	KEY_USR_VIEW \| KEY_USR_READ),
008643b8	170	KEY_ALLOC_NOT_IN_QUOTA \|
5ac7eace DH	171	KEY_ALLOC_BUILT_IN \|
5ac7eace DH	172	KEY_ALLOC_BYPASS_RESTRICTION);
b56e5a17 DH	173	if (IS_ERR(key)) {
	174	pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
	175	PTR_ERR(key));
2db68132	176	WARN_ON_ONCE(1);
b56e5a17 DH	177	} else {
	178	pr_notice("Loaded X.509 cert '%s'\n",
	179	key_ref_to_ptr(key)->description);
	180	key_ref_put(key);
	181	}
	182	p += plen;
	183	}
	184
	185	return 0;
	186
	187	dodgy_cert:
	188	pr_err("Problem parsing in-kernel X.509 certificate list\n");
	189	return 0;
	190	}
	191	late_initcall(load_system_certificate_list);
091f6e26 DH	192
	193	#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
	194
	195	/**
e68503bd DH	196	* verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
e68503bd DH	197	* @data: The data to be verified (NULL if expecting internal data).
091f6e26 DH	198	* @len: Size of @data.
	199	* @raw_pkcs7: The PKCS#7 message that is the signature.
	200	* @pkcs7_len: The size of @raw_pkcs7.
d3bfe841 DH	201	* @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
d3bfe841 DH	202	* (void *)1UL for all trusted keys).
99db4435	203	* @usage: The use to which the key is being put.
e68503bd DH	204	* @view_content: Callback to gain access to content.
e68503bd DH	205	* @ctx: Context for callback.
091f6e26	206	*/
e68503bd DH	207	int verify_pkcs7_signature(const void *data, size_t len,
	208	const void *raw_pkcs7, size_t pkcs7_len,
	209	struct key *trusted_keys,
e68503bd DH	210	enum key_being_used_for usage,
	211	int (view_content)(void ctx,
	212	const void *data, size_t len,
	213	size_t asn1hdrlen),
	214	void *ctx)
091f6e26 DH	215	{
091f6e26 DH	216	struct pkcs7_message *pkcs7;
091f6e26 DH	217	int ret;
	218
	219	pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
	220	if (IS_ERR(pkcs7))
	221	return PTR_ERR(pkcs7);
	222
	223	/* The data should be detached - so we need to supply it. */
e68503bd	224	if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
091f6e26 DH	225	pr_err("PKCS#7 signature with non-detached data\n");
	226	ret = -EBADMSG;
	227	goto error;
	228	}
	229
99db4435	230	ret = pkcs7_verify(pkcs7, usage);
091f6e26 DH	231	if (ret < 0)
	232	goto error;
	233
d3bfe841 DH	234	if (!trusted_keys) {
d3bfe841 DH	235	trusted_keys = builtin_trusted_keys;
c23268ec	236	} else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) {
d3bfe841 DH	237	#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
	238	trusted_keys = secondary_trusted_keys;
	239	#else
	240	trusted_keys = builtin_trusted_keys;
	241	#endif
	242	}
bda850cd DH	243	ret = pkcs7_validate_trust(pkcs7, trusted_keys);
	244	if (ret < 0) {
	245	if (ret == -ENOKEY)
	246	pr_err("PKCS#7 signature not signed with a trusted key\n");
e68503bd DH	247	goto error;
	248	}
	249
	250	if (view_content) {
	251	size_t asn1hdrlen;
	252
	253	ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
	254	if (ret < 0) {
	255	if (ret == -ENODATA)
	256	pr_devel("PKCS#7 message does not contain data\n");
	257	goto error;
	258	}
	259
	260	ret = view_content(ctx, data, len, asn1hdrlen);
091f6e26 DH	261	}
	262
	263	error:
	264	pkcs7_free_message(pkcs7);
	265	pr_devel("<==%s() = %d\n", __func__, ret);
	266	return ret;
	267	}
e68503bd	268	EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
091f6e26 DH	269
091f6e26 DH	270	#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
373b0cb1 DH	271
	272	#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
	273	/**
	274	* add_trusted_secondary_key - Add to secondary keyring with no validation
	275	* @source: Source of key
	276	* @data: The blob holding the key
	277	* @len: The length of the data blob
	278	*
	279	* Add a key to the secondary keyring without checking its trust chain. This
	280	* is available only during kernel initialisation.
	281	*/
	282	void __init add_trusted_secondary_key(const char *source,
	283	const void *data, size_t len)
	284	{
	285	key_ref_t key;
	286
	287	key = key_create_or_update(make_key_ref(secondary_trusted_keys, 1),
	288	"asymmetric",
	289	NULL, data, len,
	290	(KEY_POS_ALL & ~KEY_POS_SETATTR) \|
	291	KEY_USR_VIEW,
	292	KEY_ALLOC_NOT_IN_QUOTA \|
	293	KEY_ALLOC_BYPASS_RESTRICTION);
	294
	295	if (IS_ERR(key))
	296	pr_err("Problem loading %s X.509 certificate (%ld)\n",
	297	source, PTR_ERR(key));
	298	else
	299	pr_notice("Loaded %s cert '%s' linked to secondary sys keyring\n",
	300	source, key_ref_to_ptr(key)->description);
	301	}
	302	#endif /* CONFIG_SECONDARY_TRUSTED_KEYRING */