1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* incoming call handling
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/module.h>
11 #include <linux/net.h>
12 #include <linux/skbuff.h>
13 #include <linux/errqueue.h>
14 #include <linux/udp.h>
15 #include <linux/in.h>
16 #include <linux/in6.h>
17 #include <linux/icmp.h>
18 #include <linux/gfp.h>
19 #include <linux/circ_buf.h>
20 #include <net/sock.h>
21 #include <net/af_rxrpc.h>
22 #include <net/ip.h>
23 #include "ar-internal.h"
24
rxrpc_dummy_notify(struct sock * sk,struct rxrpc_call * call,unsigned long user_call_ID)25 static void rxrpc_dummy_notify(struct sock *sk, struct rxrpc_call *call,
26 unsigned long user_call_ID)
27 {
28 }
29
30 /*
31 * Preallocate a single service call, connection and peer and, if possible,
32 * give them a user ID and attach the user's side of the ID to them.
33 */
rxrpc_service_prealloc_one(struct rxrpc_sock * rx,struct rxrpc_backlog * b,rxrpc_notify_rx_t notify_rx,unsigned long user_call_ID,gfp_t gfp,unsigned int debug_id)34 static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
35 struct rxrpc_backlog *b,
36 rxrpc_notify_rx_t notify_rx,
37 unsigned long user_call_ID, gfp_t gfp,
38 unsigned int debug_id)
39 {
40 struct rxrpc_call *call, *xcall;
41 struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
42 struct rb_node *parent, **pp;
43 int max, tmp;
44 unsigned int size = RXRPC_BACKLOG_MAX;
45 unsigned int head, tail, call_head, call_tail;
46
47 max = rx->sk.sk_max_ack_backlog;
48 tmp = rx->sk.sk_ack_backlog;
49 if (tmp >= max) {
50 _leave(" = -ENOBUFS [full %u]", max);
51 return -ENOBUFS;
52 }
53 max -= tmp;
54
55 /* We don't need more conns and peers than we have calls, but on the
56 * other hand, we shouldn't ever use more peers than conns or conns
57 * than calls.
58 */
59 call_head = b->call_backlog_head;
60 call_tail = READ_ONCE(b->call_backlog_tail);
61 tmp = CIRC_CNT(call_head, call_tail, size);
62 if (tmp >= max) {
63 _leave(" = -ENOBUFS [enough %u]", tmp);
64 return -ENOBUFS;
65 }
66 max = tmp + 1;
67
68 head = b->peer_backlog_head;
69 tail = READ_ONCE(b->peer_backlog_tail);
70 if (CIRC_CNT(head, tail, size) < max) {
71 struct rxrpc_peer *peer;
72
73 peer = rxrpc_alloc_peer(rx->local, gfp, rxrpc_peer_new_prealloc);
74 if (!peer)
75 return -ENOMEM;
76 b->peer_backlog[head] = peer;
77 smp_store_release(&b->peer_backlog_head,
78 (head + 1) & (size - 1));
79 }
80
81 head = b->conn_backlog_head;
82 tail = READ_ONCE(b->conn_backlog_tail);
83 if (CIRC_CNT(head, tail, size) < max) {
84 struct rxrpc_connection *conn;
85
86 conn = rxrpc_prealloc_service_connection(rxnet, gfp);
87 if (!conn)
88 return -ENOMEM;
89 b->conn_backlog[head] = conn;
90 smp_store_release(&b->conn_backlog_head,
91 (head + 1) & (size - 1));
92 }
93
94 /* Now it gets complicated, because calls get registered with the
95 * socket here, with a user ID preassigned by the user.
96 */
97 call = rxrpc_alloc_call(rx, gfp, debug_id);
98 if (!call)
99 return -ENOMEM;
100 call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
101 rxrpc_set_call_state(call, RXRPC_CALL_SERVER_PREALLOC);
102 __set_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events);
103
104 trace_rxrpc_call(call->debug_id, refcount_read(&call->ref),
105 user_call_ID, rxrpc_call_new_prealloc_service);
106
107 write_lock(&rx->call_lock);
108
109 /* Check the user ID isn't already in use */
110 pp = &rx->calls.rb_node;
111 parent = NULL;
112 while (*pp) {
113 parent = *pp;
114 xcall = rb_entry(parent, struct rxrpc_call, sock_node);
115 if (user_call_ID < xcall->user_call_ID)
116 pp = &(*pp)->rb_left;
117 else if (user_call_ID > xcall->user_call_ID)
118 pp = &(*pp)->rb_right;
119 else
120 goto id_in_use;
121 }
122
123 call->user_call_ID = user_call_ID;
124 call->notify_rx = notify_rx;
125 if (rx->app_ops &&
126 rx->app_ops->user_attach_call) {
127 rxrpc_get_call(call, rxrpc_call_get_kernel_service);
128 rx->app_ops->user_attach_call(call, user_call_ID);
129 }
130
131 rxrpc_get_call(call, rxrpc_call_get_userid);
132 rb_link_node(&call->sock_node, parent, pp);
133 rb_insert_color(&call->sock_node, &rx->calls);
134 set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
135
136 list_add(&call->sock_link, &rx->sock_calls);
137
138 write_unlock(&rx->call_lock);
139
140 rxnet = call->rxnet;
141 spin_lock(&rxnet->call_lock);
142 list_add_tail_rcu(&call->link, &rxnet->calls);
143 spin_unlock(&rxnet->call_lock);
144
145 b->call_backlog[call_head] = call;
146 smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
147 _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
148 return 0;
149
150 id_in_use:
151 write_unlock(&rx->call_lock);
152 rxrpc_prefail_call(call, RXRPC_CALL_LOCAL_ERROR, -EBADSLT);
153 rxrpc_cleanup_call(call);
154 _leave(" = -EBADSLT");
155 return -EBADSLT;
156 }
157
158 /*
159 * Allocate the preallocation buffers for incoming service calls. These must
160 * be charged manually.
161 */
rxrpc_service_prealloc(struct rxrpc_sock * rx,gfp_t gfp)162 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
163 {
164 struct rxrpc_backlog *b = rx->backlog;
165
166 if (!b) {
167 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
168 if (!b)
169 return -ENOMEM;
170 rx->backlog = b;
171 }
172
173 return 0;
174 }
175
176 /*
177 * Discard the preallocation on a service.
178 */
rxrpc_discard_prealloc(struct rxrpc_sock * rx)179 void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
180 {
181 struct rxrpc_backlog *b = rx->backlog;
182 struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
183 unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
184
185 if (!b)
186 return;
187 rx->backlog = NULL;
188
189 /* Make sure that there aren't any incoming calls in progress before we
190 * clear the preallocation buffers.
191 */
192 spin_lock_irq(&rx->incoming_lock);
193 spin_unlock_irq(&rx->incoming_lock);
194
195 head = b->peer_backlog_head;
196 tail = b->peer_backlog_tail;
197 while (CIRC_CNT(head, tail, size) > 0) {
198 struct rxrpc_peer *peer = b->peer_backlog[tail];
199 rxrpc_put_local(peer->local, rxrpc_local_put_prealloc_peer);
200 kfree(peer);
201 tail = (tail + 1) & (size - 1);
202 }
203
204 head = b->conn_backlog_head;
205 tail = b->conn_backlog_tail;
206 while (CIRC_CNT(head, tail, size) > 0) {
207 struct rxrpc_connection *conn = b->conn_backlog[tail];
208 write_lock(&rxnet->conn_lock);
209 list_del(&conn->link);
210 list_del(&conn->proc_link);
211 write_unlock(&rxnet->conn_lock);
212 kfree(conn);
213 if (atomic_dec_and_test(&rxnet->nr_conns))
214 wake_up_var(&rxnet->nr_conns);
215 tail = (tail + 1) & (size - 1);
216 }
217
218 head = b->call_backlog_head;
219 tail = b->call_backlog_tail;
220 while (CIRC_CNT(head, tail, size) > 0) {
221 struct rxrpc_call *call = b->call_backlog[tail];
222 rxrpc_see_call(call, rxrpc_call_see_discard);
223 rcu_assign_pointer(call->socket, rx);
224 if (rx->app_ops &&
225 rx->app_ops->discard_new_call) {
226 _debug("discard %lx", call->user_call_ID);
227 rx->app_ops->discard_new_call(call, call->user_call_ID);
228 if (call->notify_rx)
229 call->notify_rx = rxrpc_dummy_notify;
230 rxrpc_put_call(call, rxrpc_call_put_kernel);
231 }
232 rxrpc_call_completed(call);
233 rxrpc_release_call(rx, call);
234 rxrpc_put_call(call, rxrpc_call_put_discard_prealloc);
235 tail = (tail + 1) & (size - 1);
236 }
237
238 kfree(b);
239 }
240
241 /*
242 * Allocate a new incoming call from the prealloc pool, along with a connection
243 * and a peer as necessary.
244 */
rxrpc_alloc_incoming_call(struct rxrpc_sock * rx,struct rxrpc_local * local,struct rxrpc_peer * peer,struct rxrpc_connection * conn,const struct rxrpc_security * sec,struct sockaddr_rxrpc * peer_srx,struct sk_buff * skb)245 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
246 struct rxrpc_local *local,
247 struct rxrpc_peer *peer,
248 struct rxrpc_connection *conn,
249 const struct rxrpc_security *sec,
250 struct sockaddr_rxrpc *peer_srx,
251 struct sk_buff *skb)
252 {
253 struct rxrpc_backlog *b = rx->backlog;
254 struct rxrpc_call *call;
255 unsigned short call_head, conn_head, peer_head;
256 unsigned short call_tail, conn_tail, peer_tail;
257 unsigned short call_count, conn_count;
258
259 if (!b)
260 return NULL;
261
262 /* #calls >= #conns >= #peers must hold true. */
263 call_head = smp_load_acquire(&b->call_backlog_head);
264 call_tail = b->call_backlog_tail;
265 call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
266 conn_head = smp_load_acquire(&b->conn_backlog_head);
267 conn_tail = b->conn_backlog_tail;
268 conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
269 ASSERTCMP(conn_count, >=, call_count);
270 peer_head = smp_load_acquire(&b->peer_backlog_head);
271 peer_tail = b->peer_backlog_tail;
272 ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
273 conn_count);
274
275 if (call_count == 0)
276 return NULL;
277
278 if (!conn) {
279 if (peer && !rxrpc_get_peer_maybe(peer, rxrpc_peer_get_service_conn))
280 peer = NULL;
281 if (!peer) {
282 peer = b->peer_backlog[peer_tail];
283 peer->srx = *peer_srx;
284 b->peer_backlog[peer_tail] = NULL;
285 smp_store_release(&b->peer_backlog_tail,
286 (peer_tail + 1) &
287 (RXRPC_BACKLOG_MAX - 1));
288
289 rxrpc_new_incoming_peer(local, peer);
290 }
291
292 /* Now allocate and set up the connection */
293 conn = b->conn_backlog[conn_tail];
294 b->conn_backlog[conn_tail] = NULL;
295 smp_store_release(&b->conn_backlog_tail,
296 (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
297 conn->local = rxrpc_get_local(local, rxrpc_local_get_prealloc_conn);
298 conn->peer = peer;
299 rxrpc_see_connection(conn, rxrpc_conn_see_new_service_conn);
300 rxrpc_new_incoming_connection(rx, conn, sec, skb);
301 } else {
302 rxrpc_get_connection(conn, rxrpc_conn_get_service_conn);
303 atomic_inc(&conn->active);
304 }
305
306 /* And now we can allocate and set up a new call */
307 call = b->call_backlog[call_tail];
308 b->call_backlog[call_tail] = NULL;
309 smp_store_release(&b->call_backlog_tail,
310 (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
311
312 rxrpc_see_call(call, rxrpc_call_see_accept);
313 call->local = rxrpc_get_local(conn->local, rxrpc_local_get_call);
314 call->conn = conn;
315 call->security = conn->security;
316 call->security_ix = conn->security_ix;
317 call->peer = rxrpc_get_peer(conn->peer, rxrpc_peer_get_accept);
318 call->dest_srx = peer->srx;
319 call->cong_ssthresh = call->peer->cong_ssthresh;
320 call->tx_last_sent = ktime_get_real();
321 return call;
322 }
323
324 /*
325 * Set up a new incoming call. Called from the I/O thread.
326 *
327 * If this is for a kernel service, when we allocate the call, it will have
328 * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
329 * retainer ref obtained from the backlog buffer. Prealloc calls for userspace
330 * services only have the ref from the backlog buffer.
331 *
332 * If we want to report an error, we mark the skb with the packet type and
333 * abort code and return false.
334 */
rxrpc_new_incoming_call(struct rxrpc_local * local,struct rxrpc_peer * peer,struct rxrpc_connection * conn,struct sockaddr_rxrpc * peer_srx,struct sk_buff * skb)335 bool rxrpc_new_incoming_call(struct rxrpc_local *local,
336 struct rxrpc_peer *peer,
337 struct rxrpc_connection *conn,
338 struct sockaddr_rxrpc *peer_srx,
339 struct sk_buff *skb)
340 {
341 const struct rxrpc_security *sec = NULL;
342 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
343 struct rxrpc_call *call = NULL;
344 struct rxrpc_sock *rx;
345
346 _enter("");
347
348 /* Don't set up a call for anything other than a DATA packet. */
349 if (sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
350 return rxrpc_protocol_error(skb, rxrpc_eproto_no_service_call);
351
352 read_lock_irq(&local->services_lock);
353
354 /* Weed out packets to services we're not offering. Packets that would
355 * begin a call are explicitly rejected and the rest are just
356 * discarded.
357 */
358 rx = local->service;
359 if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
360 sp->hdr.serviceId != rx->second_service)
361 ) {
362 if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
363 sp->hdr.seq == 1)
364 goto unsupported_service;
365 goto discard;
366 }
367
368 if (!conn) {
369 sec = rxrpc_get_incoming_security(rx, skb);
370 if (!sec)
371 goto unsupported_security;
372 }
373
374 spin_lock(&rx->incoming_lock);
375 if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
376 rx->sk.sk_state == RXRPC_CLOSE) {
377 rxrpc_direct_conn_abort(skb, rxrpc_abort_shut_down,
378 RX_INVALID_OPERATION, -ESHUTDOWN);
379 goto no_call;
380 }
381
382 call = rxrpc_alloc_incoming_call(rx, local, peer, conn, sec, peer_srx,
383 skb);
384 if (!call) {
385 skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
386 goto no_call;
387 }
388
389 trace_rxrpc_receive(call, rxrpc_receive_incoming,
390 sp->hdr.serial, sp->hdr.seq);
391
392 /* Make the call live. */
393 rxrpc_incoming_call(rx, call, skb);
394 conn = call->conn;
395
396 if (rx->app_ops &&
397 rx->app_ops->notify_new_call)
398 rx->app_ops->notify_new_call(&rx->sk, call, call->user_call_ID);
399
400 spin_lock(&conn->state_lock);
401 if (conn->state == RXRPC_CONN_SERVICE_UNSECURED) {
402 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
403 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
404 rxrpc_queue_conn(call->conn, rxrpc_conn_queue_challenge);
405 }
406 spin_unlock(&conn->state_lock);
407
408 spin_unlock(&rx->incoming_lock);
409 read_unlock_irq(&local->services_lock);
410 rxrpc_assess_MTU_size(local, call->peer);
411
412 if (hlist_unhashed(&call->error_link)) {
413 spin_lock_irq(&call->peer->lock);
414 hlist_add_head(&call->error_link, &call->peer->error_targets);
415 spin_unlock_irq(&call->peer->lock);
416 }
417
418 _leave(" = %p{%d}", call, call->debug_id);
419 rxrpc_queue_rx_call_packet(call, skb);
420 rxrpc_put_call(call, rxrpc_call_put_input);
421 return true;
422
423 unsupported_service:
424 read_unlock_irq(&local->services_lock);
425 return rxrpc_direct_conn_abort(skb, rxrpc_abort_service_not_offered,
426 RX_INVALID_OPERATION, -EOPNOTSUPP);
427 unsupported_security:
428 read_unlock_irq(&local->services_lock);
429 return rxrpc_direct_conn_abort(skb, rxrpc_abort_service_not_offered,
430 RX_INVALID_OPERATION, -EKEYREJECTED);
431 no_call:
432 spin_unlock(&rx->incoming_lock);
433 read_unlock_irq(&local->services_lock);
434 _leave(" = f [%u]", skb->mark);
435 return false;
436 discard:
437 read_unlock_irq(&local->services_lock);
438 return true;
439 }
440
441 /*
442 * Charge up socket with preallocated calls, attaching user call IDs.
443 */
rxrpc_user_charge_accept(struct rxrpc_sock * rx,unsigned long user_call_ID)444 int rxrpc_user_charge_accept(struct rxrpc_sock *rx, unsigned long user_call_ID)
445 {
446 struct rxrpc_backlog *b = rx->backlog;
447
448 if (rx->sk.sk_state == RXRPC_CLOSE)
449 return -ESHUTDOWN;
450
451 return rxrpc_service_prealloc_one(rx, b, NULL, user_call_ID, GFP_KERNEL,
452 atomic_inc_return(&rxrpc_debug_id));
453 }
454
455 /*
456 * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
457 * @sock: The socket on which to preallocate
458 * @notify_rx: Event notification function for the call
459 * @user_call_ID: The tag to attach to the preallocated call
460 * @gfp: The allocation conditions.
461 * @debug_id: The tracing debug ID.
462 *
463 * Charge up the socket with preallocated calls, each with a user ID. The
464 * ->user_attach_call() callback function should be provided to effect the
465 * attachment from the user's side. The user is given a ref to hold on the
466 * call.
467 *
468 * Note that the call may be come connected before this function returns.
469 */
rxrpc_kernel_charge_accept(struct socket * sock,rxrpc_notify_rx_t notify_rx,unsigned long user_call_ID,gfp_t gfp,unsigned int debug_id)470 int rxrpc_kernel_charge_accept(struct socket *sock, rxrpc_notify_rx_t notify_rx,
471 unsigned long user_call_ID, gfp_t gfp,
472 unsigned int debug_id)
473 {
474 struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
475 struct rxrpc_backlog *b = rx->backlog;
476
477 if (sock->sk->sk_state == RXRPC_CLOSE)
478 return -ESHUTDOWN;
479
480 return rxrpc_service_prealloc_one(rx, b, notify_rx, user_call_ID,
481 gfp, debug_id);
482 }
483 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);
484