1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Establish a TLS session for a kernel socket consumer
4 * using the tlshd user space handler.
5 *
6 * Author: Chuck Lever <chuck.lever@oracle.com>
7 *
8 * Copyright (c) 2021-2023, Oracle and/or its affiliates.
9 */
10
11#include <linux/types.h>
12#include <linux/socket.h>
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/slab.h>
16#include <linux/key.h>
17
18#include <net/sock.h>
19#include <net/handshake.h>
20#include <net/genetlink.h>
21#include <net/tls_prot.h>
22
23#include <uapi/linux/keyctl.h>
24#include <uapi/linux/handshake.h>
25#include "handshake.h"
26
27struct tls_handshake_req {
28	void			(*th_consumer_done)(void *data, int status,
29						    key_serial_t peerid);
30	void			*th_consumer_data;
31
32	int			th_type;
33	unsigned int		th_timeout_ms;
34	int			th_auth_mode;
35	const char		*th_peername;
36	key_serial_t		th_keyring;
37	key_serial_t		th_certificate;
38	key_serial_t		th_privkey;
39
40	unsigned int		th_num_peerids;
41	key_serial_t		th_peerid[5];
42};
43
44static struct tls_handshake_req *
45tls_handshake_req_init(struct handshake_req *req,
46		       const struct tls_handshake_args *args)
47{
48	struct tls_handshake_req *treq = handshake_req_private(req);
49
50	treq->th_timeout_ms = args->ta_timeout_ms;
51	treq->th_consumer_done = args->ta_done;
52	treq->th_consumer_data = args->ta_data;
53	treq->th_peername = args->ta_peername;
54	treq->th_keyring = args->ta_keyring;
55	treq->th_num_peerids = 0;
56	treq->th_certificate = TLS_NO_CERT;
57	treq->th_privkey = TLS_NO_PRIVKEY;
58	return treq;
59}
60
61static void tls_handshake_remote_peerids(struct tls_handshake_req *treq,
62					 struct genl_info *info)
63{
64	struct nlattr *head = nlmsg_attrdata(info->nlhdr, GENL_HDRLEN);
65	int rem, len = nlmsg_attrlen(info->nlhdr, GENL_HDRLEN);
66	struct nlattr *nla;
67	unsigned int i;
68
69	i = 0;
70	nla_for_each_attr(nla, head, len, rem) {
71		if (nla_type(nla) == HANDSHAKE_A_DONE_REMOTE_AUTH)
72			i++;
73	}
74	if (!i)
75		return;
76	treq->th_num_peerids = min_t(unsigned int, i,
77				     ARRAY_SIZE(treq->th_peerid));
78
79	i = 0;
80	nla_for_each_attr(nla, head, len, rem) {
81		if (nla_type(nla) == HANDSHAKE_A_DONE_REMOTE_AUTH)
82			treq->th_peerid[i++] = nla_get_u32(nla);
83		if (i >= treq->th_num_peerids)
84			break;
85	}
86}
87
88/**
89 * tls_handshake_done - callback to handle a CMD_DONE request
90 * @req: socket on which the handshake was performed
91 * @status: session status code
92 * @info: full results of session establishment
93 *
94 */
95static void tls_handshake_done(struct handshake_req *req,
96			       unsigned int status, struct genl_info *info)
97{
98	struct tls_handshake_req *treq = handshake_req_private(req);
99
100	treq->th_peerid[0] = TLS_NO_PEERID;
101	if (info)
102		tls_handshake_remote_peerids(treq, info);
103
104	if (!status)
105		set_bit(HANDSHAKE_F_REQ_SESSION, &req->hr_flags);
106
107	treq->th_consumer_done(treq->th_consumer_data, -status,
108			       treq->th_peerid[0]);
109}
110
111#if IS_ENABLED(CONFIG_KEYS)
112static int tls_handshake_private_keyring(struct tls_handshake_req *treq)
113{
114	key_ref_t process_keyring_ref, keyring_ref;
115	int ret;
116
117	if (treq->th_keyring == TLS_NO_KEYRING)
118		return 0;
119
120	process_keyring_ref = lookup_user_key(KEY_SPEC_PROCESS_KEYRING,
121					      KEY_LOOKUP_CREATE,
122					      KEY_NEED_WRITE);
123	if (IS_ERR(process_keyring_ref)) {
124		ret = PTR_ERR(process_keyring_ref);
125		goto out;
126	}
127
128	keyring_ref = lookup_user_key(treq->th_keyring, KEY_LOOKUP_CREATE,
129				      KEY_NEED_LINK);
130	if (IS_ERR(keyring_ref)) {
131		ret = PTR_ERR(keyring_ref);
132		goto out_put_key;
133	}
134
135	ret = key_link(key_ref_to_ptr(process_keyring_ref),
136		       key_ref_to_ptr(keyring_ref));
137
138	key_ref_put(keyring_ref);
139out_put_key:
140	key_ref_put(process_keyring_ref);
141out:
142	return ret;
143}
144#else
145static int tls_handshake_private_keyring(struct tls_handshake_req *treq)
146{
147	return 0;
148}
149#endif
150
151static int tls_handshake_put_peer_identity(struct sk_buff *msg,
152					   struct tls_handshake_req *treq)
153{
154	unsigned int i;
155
156	for (i = 0; i < treq->th_num_peerids; i++)
157		if (nla_put_u32(msg, HANDSHAKE_A_ACCEPT_PEER_IDENTITY,
158				treq->th_peerid[i]) < 0)
159			return -EMSGSIZE;
160	return 0;
161}
162
163static int tls_handshake_put_certificate(struct sk_buff *msg,
164					 struct tls_handshake_req *treq)
165{
166	struct nlattr *entry_attr;
167
168	if (treq->th_certificate == TLS_NO_CERT &&
169	    treq->th_privkey == TLS_NO_PRIVKEY)
170		return 0;
171
172	entry_attr = nla_nest_start(msg, HANDSHAKE_A_ACCEPT_CERTIFICATE);
173	if (!entry_attr)
174		return -EMSGSIZE;
175
176	if (nla_put_s32(msg, HANDSHAKE_A_X509_CERT,
177			treq->th_certificate) ||
178	    nla_put_s32(msg, HANDSHAKE_A_X509_PRIVKEY,
179			treq->th_privkey)) {
180		nla_nest_cancel(msg, entry_attr);
181		return -EMSGSIZE;
182	}
183
184	nla_nest_end(msg, entry_attr);
185	return 0;
186}
187
188/**
189 * tls_handshake_accept - callback to construct a CMD_ACCEPT response
190 * @req: handshake parameters to return
191 * @info: generic netlink message context
192 * @fd: file descriptor to be returned
193 *
194 * Returns zero on success, or a negative errno on failure.
195 */
196static int tls_handshake_accept(struct handshake_req *req,
197				struct genl_info *info, int fd)
198{
199	struct tls_handshake_req *treq = handshake_req_private(req);
200	struct nlmsghdr *hdr;
201	struct sk_buff *msg;
202	int ret;
203
204	ret = tls_handshake_private_keyring(treq);
205	if (ret < 0)
206		goto out;
207
208	ret = -ENOMEM;
209	msg = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
210	if (!msg)
211		goto out;
212	hdr = handshake_genl_put(msg, info);
213	if (!hdr)
214		goto out_cancel;
215
216	ret = -EMSGSIZE;
217	ret = nla_put_s32(msg, HANDSHAKE_A_ACCEPT_SOCKFD, fd);
218	if (ret < 0)
219		goto out_cancel;
220	ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_MESSAGE_TYPE, treq->th_type);
221	if (ret < 0)
222		goto out_cancel;
223	if (treq->th_peername) {
224		ret = nla_put_string(msg, HANDSHAKE_A_ACCEPT_PEERNAME,
225				     treq->th_peername);
226		if (ret < 0)
227			goto out_cancel;
228	}
229	if (treq->th_timeout_ms) {
230		ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_TIMEOUT, treq->th_timeout_ms);
231		if (ret < 0)
232			goto out_cancel;
233	}
234
235	ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_AUTH_MODE,
236			  treq->th_auth_mode);
237	if (ret < 0)
238		goto out_cancel;
239	switch (treq->th_auth_mode) {
240	case HANDSHAKE_AUTH_PSK:
241		ret = tls_handshake_put_peer_identity(msg, treq);
242		if (ret < 0)
243			goto out_cancel;
244		break;
245	case HANDSHAKE_AUTH_X509:
246		ret = tls_handshake_put_certificate(msg, treq);
247		if (ret < 0)
248			goto out_cancel;
249		break;
250	}
251
252	genlmsg_end(msg, hdr);
253	return genlmsg_reply(msg, info);
254
255out_cancel:
256	genlmsg_cancel(msg, hdr);
257out:
258	return ret;
259}
260
261static const struct handshake_proto tls_handshake_proto = {
262	.hp_handler_class	= HANDSHAKE_HANDLER_CLASS_TLSHD,
263	.hp_privsize		= sizeof(struct tls_handshake_req),
264	.hp_flags		= BIT(HANDSHAKE_F_PROTO_NOTIFY),
265
266	.hp_accept		= tls_handshake_accept,
267	.hp_done		= tls_handshake_done,
268};
269
270/**
271 * tls_client_hello_anon - request an anonymous TLS handshake on a socket
272 * @args: socket and handshake parameters for this request
273 * @flags: memory allocation control flags
274 *
275 * Return values:
276 *   %0: Handshake request enqueue; ->done will be called when complete
277 *   %-ESRCH: No user agent is available
278 *   %-ENOMEM: Memory allocation failed
279 */
280int tls_client_hello_anon(const struct tls_handshake_args *args, gfp_t flags)
281{
282	struct tls_handshake_req *treq;
283	struct handshake_req *req;
284
285	req = handshake_req_alloc(&tls_handshake_proto, flags);
286	if (!req)
287		return -ENOMEM;
288	treq = tls_handshake_req_init(req, args);
289	treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTHELLO;
290	treq->th_auth_mode = HANDSHAKE_AUTH_UNAUTH;
291
292	return handshake_req_submit(args->ta_sock, req, flags);
293}
294EXPORT_SYMBOL(tls_client_hello_anon);
295
296/**
297 * tls_client_hello_x509 - request an x.509-based TLS handshake on a socket
298 * @args: socket and handshake parameters for this request
299 * @flags: memory allocation control flags
300 *
301 * Return values:
302 *   %0: Handshake request enqueue; ->done will be called when complete
303 *   %-ESRCH: No user agent is available
304 *   %-ENOMEM: Memory allocation failed
305 */
306int tls_client_hello_x509(const struct tls_handshake_args *args, gfp_t flags)
307{
308	struct tls_handshake_req *treq;
309	struct handshake_req *req;
310
311	req = handshake_req_alloc(&tls_handshake_proto, flags);
312	if (!req)
313		return -ENOMEM;
314	treq = tls_handshake_req_init(req, args);
315	treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTHELLO;
316	treq->th_auth_mode = HANDSHAKE_AUTH_X509;
317	treq->th_certificate = args->ta_my_cert;
318	treq->th_privkey = args->ta_my_privkey;
319
320	return handshake_req_submit(args->ta_sock, req, flags);
321}
322EXPORT_SYMBOL(tls_client_hello_x509);
323
324/**
325 * tls_client_hello_psk - request a PSK-based TLS handshake on a socket
326 * @args: socket and handshake parameters for this request
327 * @flags: memory allocation control flags
328 *
329 * Return values:
330 *   %0: Handshake request enqueue; ->done will be called when complete
331 *   %-EINVAL: Wrong number of local peer IDs
332 *   %-ESRCH: No user agent is available
333 *   %-ENOMEM: Memory allocation failed
334 */
335int tls_client_hello_psk(const struct tls_handshake_args *args, gfp_t flags)
336{
337	struct tls_handshake_req *treq;
338	struct handshake_req *req;
339	unsigned int i;
340
341	if (!args->ta_num_peerids ||
342	    args->ta_num_peerids > ARRAY_SIZE(treq->th_peerid))
343		return -EINVAL;
344
345	req = handshake_req_alloc(&tls_handshake_proto, flags);
346	if (!req)
347		return -ENOMEM;
348	treq = tls_handshake_req_init(req, args);
349	treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTHELLO;
350	treq->th_auth_mode = HANDSHAKE_AUTH_PSK;
351	treq->th_num_peerids = args->ta_num_peerids;
352	for (i = 0; i < args->ta_num_peerids; i++)
353		treq->th_peerid[i] = args->ta_my_peerids[i];
354
355	return handshake_req_submit(args->ta_sock, req, flags);
356}
357EXPORT_SYMBOL(tls_client_hello_psk);
358
359/**
360 * tls_server_hello_x509 - request a server TLS handshake on a socket
361 * @args: socket and handshake parameters for this request
362 * @flags: memory allocation control flags
363 *
364 * Return values:
365 *   %0: Handshake request enqueue; ->done will be called when complete
366 *   %-ESRCH: No user agent is available
367 *   %-ENOMEM: Memory allocation failed
368 */
369int tls_server_hello_x509(const struct tls_handshake_args *args, gfp_t flags)
370{
371	struct tls_handshake_req *treq;
372	struct handshake_req *req;
373
374	req = handshake_req_alloc(&tls_handshake_proto, flags);
375	if (!req)
376		return -ENOMEM;
377	treq = tls_handshake_req_init(req, args);
378	treq->th_type = HANDSHAKE_MSG_TYPE_SERVERHELLO;
379	treq->th_auth_mode = HANDSHAKE_AUTH_X509;
380	treq->th_certificate = args->ta_my_cert;
381	treq->th_privkey = args->ta_my_privkey;
382
383	return handshake_req_submit(args->ta_sock, req, flags);
384}
385EXPORT_SYMBOL(tls_server_hello_x509);
386
387/**
388 * tls_server_hello_psk - request a server TLS handshake on a socket
389 * @args: socket and handshake parameters for this request
390 * @flags: memory allocation control flags
391 *
392 * Return values:
393 *   %0: Handshake request enqueue; ->done will be called when complete
394 *   %-ESRCH: No user agent is available
395 *   %-ENOMEM: Memory allocation failed
396 */
397int tls_server_hello_psk(const struct tls_handshake_args *args, gfp_t flags)
398{
399	struct tls_handshake_req *treq;
400	struct handshake_req *req;
401
402	req = handshake_req_alloc(&tls_handshake_proto, flags);
403	if (!req)
404		return -ENOMEM;
405	treq = tls_handshake_req_init(req, args);
406	treq->th_type = HANDSHAKE_MSG_TYPE_SERVERHELLO;
407	treq->th_auth_mode = HANDSHAKE_AUTH_PSK;
408	treq->th_num_peerids = 1;
409	treq->th_peerid[0] = args->ta_my_peerids[0];
410
411	return handshake_req_submit(args->ta_sock, req, flags);
412}
413EXPORT_SYMBOL(tls_server_hello_psk);
414
415/**
416 * tls_handshake_cancel - cancel a pending handshake
417 * @sk: socket on which there is an ongoing handshake
418 *
419 * Request cancellation races with request completion. To determine
420 * who won, callers examine the return value from this function.
421 *
422 * Return values:
423 *   %true - Uncompleted handshake request was canceled
424 *   %false - Handshake request already completed or not found
425 */
426bool tls_handshake_cancel(struct sock *sk)
427{
428	return handshake_req_cancel(sk);
429}
430EXPORT_SYMBOL(tls_handshake_cancel);
431
432/**
433 * tls_handshake_close - send a Closure alert
434 * @sock: an open socket
435 *
436 */
437void tls_handshake_close(struct socket *sock)
438{
439	struct handshake_req *req;
440
441	req = handshake_req_hash_lookup(sock->sk);
442	if (!req)
443		return;
444	if (!test_and_clear_bit(HANDSHAKE_F_REQ_SESSION, &req->hr_flags))
445		return;
446	tls_alert_send(sock, TLS_ALERT_LEVEL_WARNING,
447		       TLS_ALERT_DESC_CLOSE_NOTIFY);
448}
449EXPORT_SYMBOL(tls_handshake_close);
450