keyring.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (c) 2023 Hannes Reinecke, SUSE Labs
  4 */
  5
  6#include <linux/module.h>
  7#include <linux/seq_file.h>
  8#include <linux/key-type.h>
  9#include <keys/user-type.h>
 10#include <linux/nvme.h>
 11#include <linux/nvme-tcp.h>
 12#include <linux/nvme-keyring.h>
 13
 14static struct key *nvme_keyring;
 15
 16key_serial_t nvme_keyring_id(void)
 17{
 18	return nvme_keyring->serial;
 19}
 20EXPORT_SYMBOL_GPL(nvme_keyring_id);
 21
 22static bool nvme_tls_psk_revoked(struct key *psk)
 23{
 24	return test_bit(KEY_FLAG_REVOKED, &psk->flags) ||
 25		test_bit(KEY_FLAG_INVALIDATED, &psk->flags);
 26}
 27
 28struct key *nvme_tls_key_lookup(key_serial_t key_id)
 29{
 30	struct key *key = key_lookup(key_id);
 31
 32	if (IS_ERR(key)) {
 33		pr_err("key id %08x not found\n", key_id);
 34		return key;
 35	}
 36	if (nvme_tls_psk_revoked(key)) {
 37		pr_err("key id %08x revoked\n", key_id);
 38		return ERR_PTR(-EKEYREVOKED);
 39	}
 40	return key;
 41}
 42EXPORT_SYMBOL_GPL(nvme_tls_key_lookup);
 43
 44static void nvme_tls_psk_describe(const struct key *key, struct seq_file *m)
 45{
 46	seq_puts(m, key->description);
 47	seq_printf(m, ": %u", key->datalen);
 48}
 49
 50static bool nvme_tls_psk_match(const struct key *key,
 51			       const struct key_match_data *match_data)
 52{
 53	const char *match_id;
 54	size_t match_len;
 55
 56	if (!key->description) {
 57		pr_debug("%s: no key description\n", __func__);
 58		return false;
 59	}
 60	if (!match_data->raw_data) {
 61		pr_debug("%s: no match data\n", __func__);
 62		return false;
 63	}
 64	match_id = match_data->raw_data;
 65	match_len = strlen(match_id);
 66	pr_debug("%s: match '%s' '%s' len %zd\n",
 67		 __func__, match_id, key->description, match_len);
 68	return !memcmp(key->description, match_id, match_len);
 69}
 70
 71static int nvme_tls_psk_match_preparse(struct key_match_data *match_data)
 72{
 73	match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
 74	match_data->cmp = nvme_tls_psk_match;
 75	return 0;
 76}
 77
 78static struct key_type nvme_tls_psk_key_type = {
 79	.name           = "psk",
 80	.flags          = KEY_TYPE_NET_DOMAIN,
 81	.preparse       = user_preparse,
 82	.free_preparse  = user_free_preparse,
 83	.match_preparse = nvme_tls_psk_match_preparse,
 84	.instantiate    = generic_key_instantiate,
 85	.revoke         = user_revoke,
 86	.destroy        = user_destroy,
 87	.describe       = nvme_tls_psk_describe,
 88	.read           = user_read,
 89};
 90
 91static struct key *nvme_tls_psk_lookup(struct key *keyring,
 92		const char *hostnqn, const char *subnqn,
 93		u8 hmac, u8 psk_ver, bool generated)
 94{
 95	char *identity;
 96	size_t identity_len = (NVMF_NQN_SIZE) * 2 + 11;
 97	key_ref_t keyref;
 98	key_serial_t keyring_id;
 99
100	identity = kzalloc(identity_len, GFP_KERNEL);
101	if (!identity)
102		return ERR_PTR(-ENOMEM);
103
104	snprintf(identity, identity_len, "NVMe%u%c%02u %s %s",
105		 psk_ver, generated ? 'G' : 'R', hmac, hostnqn, subnqn);
106
107	if (!keyring)
108		keyring = nvme_keyring;
109	keyring_id = key_serial(keyring);
110	pr_debug("keyring %x lookup tls psk '%s'\n",
111		 keyring_id, identity);
112	keyref = keyring_search(make_key_ref(keyring, true),
113				&nvme_tls_psk_key_type,
114				identity, false);
115	if (IS_ERR(keyref)) {
116		pr_debug("lookup tls psk '%s' failed, error %ld\n",
117			 identity, PTR_ERR(keyref));
118		kfree(identity);
119		return ERR_PTR(-ENOKEY);
120	}
121	kfree(identity);
122
123	return key_ref_to_ptr(keyref);
124}
125
126/**
127 * nvme_tls_psk_refresh - Refresh TLS PSK
128 * @keyring: Keyring holding the TLS PSK
129 * @hostnqn: Host NQN to use
130 * @subnqn: Subsystem NQN to use
131 * @hmac_id: Hash function identifier
132 * @data: TLS PSK key material
133 * @data_len: Length of @data
134 * @digest: TLS PSK digest
135 *
136 * Refresh a generated version 1 TLS PSK with the identity generated
137 * from @hmac_id, @hostnqn, @subnqn, and @digest in the keyring given
138 * by @keyring.
139 *
140 * Returns the updated key success or an error pointer otherwise.
141 */
142struct key *nvme_tls_psk_refresh(struct key *keyring,
143		const char *hostnqn, const char *subnqn, u8 hmac_id,
144		u8 *data, size_t data_len, const char *digest)
145{
146	key_perm_t keyperm =
147		KEY_POS_SEARCH | KEY_POS_VIEW | KEY_POS_READ |
148		KEY_POS_WRITE | KEY_POS_LINK | KEY_POS_SETATTR |
149		KEY_USR_SEARCH | KEY_USR_VIEW | KEY_USR_READ;
150	char *identity;
151	key_ref_t keyref;
152	key_serial_t keyring_id;
153	struct key *key;
154
155	if (!hostnqn || !subnqn || !data || !data_len)
156		return ERR_PTR(-EINVAL);
157
158	identity = kasprintf(GFP_KERNEL, "NVMe1G%02d %s %s %s",
159		 hmac_id, hostnqn, subnqn, digest);
160	if (!identity)
161		return ERR_PTR(-ENOMEM);
162
163	if (!keyring)
164		keyring = nvme_keyring;
165	keyring_id = key_serial(keyring);
166	pr_debug("keyring %x refresh tls psk '%s'\n",
167		 keyring_id, identity);
168	keyref = key_create_or_update(make_key_ref(keyring, true),
169				"psk", identity, data, data_len,
170				keyperm, KEY_ALLOC_NOT_IN_QUOTA |
171				      KEY_ALLOC_BUILT_IN |
172				      KEY_ALLOC_BYPASS_RESTRICTION);
173	if (IS_ERR(keyref)) {
174		pr_debug("refresh tls psk '%s' failed, error %ld\n",
175			 identity, PTR_ERR(keyref));
176		kfree(identity);
177		return ERR_PTR(-ENOKEY);
178	}
179	kfree(identity);
180	/*
181	 * Set the default timeout to 1 hour
182	 * as suggested in TP8018.
183	 */
184	key = key_ref_to_ptr(keyref);
185	key_set_timeout(key, 3600);
186	return key;
187}
188EXPORT_SYMBOL_GPL(nvme_tls_psk_refresh);
189
190/*
191 * NVMe PSK priority list
192 *
193 * 'Retained' PSKs (ie 'generated == false') should be preferred to 'generated'
194 * PSKs, PSKs with hash (psk_ver 1) should be preferred to PSKs without hash
195 * (psk_ver 0), and SHA-384 should be preferred to SHA-256.
196 */
197static struct nvme_tls_psk_priority_list {
198	bool generated;
199	u8 psk_ver;
200	enum nvme_tcp_tls_cipher cipher;
201} nvme_tls_psk_prio[] = {
202	{ .generated = false,
203	  .psk_ver = 1,
204	  .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
205	{ .generated = false,
206	  .psk_ver = 1,
207	  .cipher = NVME_TCP_TLS_CIPHER_SHA256, },
208	{ .generated = false,
209	  .psk_ver = 0,
210	  .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
211	{ .generated = false,
212	  .psk_ver = 0,
213	  .cipher = NVME_TCP_TLS_CIPHER_SHA256, },
214	{ .generated = true,
215	  .psk_ver = 1,
216	  .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
217	{ .generated = true,
218	  .psk_ver = 1,
219	  .cipher = NVME_TCP_TLS_CIPHER_SHA256, },
220	{ .generated = true,
221	  .psk_ver = 0,
222	  .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
223	{ .generated = true,
224	  .psk_ver = 0,
225	  .cipher = NVME_TCP_TLS_CIPHER_SHA256, },
226};
227
228/*
229 * nvme_tls_psk_default - Return the preferred PSK to use for TLS ClientHello
230 */
231key_serial_t nvme_tls_psk_default(struct key *keyring,
232		      const char *hostnqn, const char *subnqn)
233{
234	struct key *tls_key;
235	key_serial_t tls_key_id;
236	int prio;
237
238	for (prio = 0; prio < ARRAY_SIZE(nvme_tls_psk_prio); prio++) {
239		bool generated = nvme_tls_psk_prio[prio].generated;
240		u8 ver = nvme_tls_psk_prio[prio].psk_ver;
241		enum nvme_tcp_tls_cipher cipher = nvme_tls_psk_prio[prio].cipher;
242
243		tls_key = nvme_tls_psk_lookup(keyring, hostnqn, subnqn,
244					      cipher, ver, generated);
245		if (!IS_ERR(tls_key)) {
246			tls_key_id = tls_key->serial;
247			key_put(tls_key);
248			return tls_key_id;
249		}
250	}
251	return 0;
252}
253EXPORT_SYMBOL_GPL(nvme_tls_psk_default);
254
255static int __init nvme_keyring_init(void)
256{
257	int err;
258
259	nvme_keyring = keyring_alloc(".nvme",
260				     GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
261				     current_cred(),
262				     (KEY_POS_ALL & ~KEY_POS_SETATTR) |
263				     (KEY_USR_ALL & ~KEY_USR_SETATTR),
264				     KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
265	if (IS_ERR(nvme_keyring))
266		return PTR_ERR(nvme_keyring);
267
268	err = register_key_type(&nvme_tls_psk_key_type);
269	if (err) {
270		key_put(nvme_keyring);
271		return err;
272	}
273	return 0;
274}
275
276static void __exit nvme_keyring_exit(void)
277{
278	unregister_key_type(&nvme_tls_psk_key_type);
279	key_revoke(nvme_keyring);
280	key_put(nvme_keyring);
281}
282
283MODULE_LICENSE("GPL v2");
284MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
285MODULE_DESCRIPTION("NVMe Keyring implementation");
286module_init(nvme_keyring_init);
287module_exit(nvme_keyring_exit);