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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Peer event handling, typically ICMP messages.
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/module.h>
9#include <linux/net.h>
10#include <linux/skbuff.h>
11#include <linux/errqueue.h>
12#include <linux/udp.h>
13#include <linux/in.h>
14#include <linux/in6.h>
15#include <linux/icmp.h>
16#include <net/sock.h>
17#include <net/af_rxrpc.h>
18#include <net/ip.h>
19#include "ar-internal.h"
20
21static void rxrpc_store_error(struct rxrpc_peer *, struct sk_buff *);
22static void rxrpc_distribute_error(struct rxrpc_peer *, struct sk_buff *,
23 enum rxrpc_call_completion, int);
24
25/*
26 * Find the peer associated with a local error.
27 */
28static struct rxrpc_peer *rxrpc_lookup_peer_local_rcu(struct rxrpc_local *local,
29 const struct sk_buff *skb,
30 struct sockaddr_rxrpc *srx)
31{
32 struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
33
34 _enter("");
35
36 memset(srx, 0, sizeof(*srx));
37 srx->transport_type = local->srx.transport_type;
38 srx->transport_len = local->srx.transport_len;
39 srx->transport.family = local->srx.transport.family;
40
41 /* Can we see an ICMP4 packet on an ICMP6 listening socket? and vice
42 * versa?
43 */
44 switch (srx->transport.family) {
45 case AF_INET:
46 srx->transport_len = sizeof(srx->transport.sin);
47 srx->transport.family = AF_INET;
48 srx->transport.sin.sin_port = serr->port;
49 switch (serr->ee.ee_origin) {
50 case SO_EE_ORIGIN_ICMP:
51 memcpy(&srx->transport.sin.sin_addr,
52 skb_network_header(skb) + serr->addr_offset,
53 sizeof(struct in_addr));
54 break;
55 case SO_EE_ORIGIN_ICMP6:
56 memcpy(&srx->transport.sin.sin_addr,
57 skb_network_header(skb) + serr->addr_offset + 12,
58 sizeof(struct in_addr));
59 break;
60 default:
61 memcpy(&srx->transport.sin.sin_addr, &ip_hdr(skb)->saddr,
62 sizeof(struct in_addr));
63 break;
64 }
65 break;
66
67#ifdef CONFIG_AF_RXRPC_IPV6
68 case AF_INET6:
69 switch (serr->ee.ee_origin) {
70 case SO_EE_ORIGIN_ICMP6:
71 srx->transport.sin6.sin6_port = serr->port;
72 memcpy(&srx->transport.sin6.sin6_addr,
73 skb_network_header(skb) + serr->addr_offset,
74 sizeof(struct in6_addr));
75 break;
76 case SO_EE_ORIGIN_ICMP:
77 srx->transport_len = sizeof(srx->transport.sin);
78 srx->transport.family = AF_INET;
79 srx->transport.sin.sin_port = serr->port;
80 memcpy(&srx->transport.sin.sin_addr,
81 skb_network_header(skb) + serr->addr_offset,
82 sizeof(struct in_addr));
83 break;
84 default:
85 memcpy(&srx->transport.sin6.sin6_addr,
86 &ipv6_hdr(skb)->saddr,
87 sizeof(struct in6_addr));
88 break;
89 }
90 break;
91#endif
92
93 default:
94 BUG();
95 }
96
97 return rxrpc_lookup_peer_rcu(local, srx);
98}
99
100/*
101 * Handle an MTU/fragmentation problem.
102 */
103static void rxrpc_adjust_mtu(struct rxrpc_peer *peer, unsigned int mtu)
104{
105 /* wind down the local interface MTU */
106 if (mtu > 0 && peer->if_mtu == 65535 && mtu < peer->if_mtu)
107 peer->if_mtu = mtu;
108
109 if (mtu == 0) {
110 /* they didn't give us a size, estimate one */
111 mtu = peer->if_mtu;
112 if (mtu > 1500) {
113 mtu >>= 1;
114 if (mtu < 1500)
115 mtu = 1500;
116 } else {
117 mtu -= 100;
118 if (mtu < peer->hdrsize)
119 mtu = peer->hdrsize + 4;
120 }
121 }
122
123 if (mtu < peer->mtu) {
124 spin_lock(&peer->lock);
125 peer->mtu = mtu;
126 peer->maxdata = peer->mtu - peer->hdrsize;
127 spin_unlock(&peer->lock);
128 }
129}
130
131/*
132 * Handle an error received on the local endpoint.
133 */
134void rxrpc_input_error(struct rxrpc_local *local, struct sk_buff *skb)
135{
136 struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
137 struct sockaddr_rxrpc srx;
138 struct rxrpc_peer *peer = NULL;
139
140 _enter("L=%x", local->debug_id);
141
142 if (!skb->len && serr->ee.ee_origin == SO_EE_ORIGIN_TIMESTAMPING) {
143 _leave("UDP empty message");
144 return;
145 }
146
147 rcu_read_lock();
148 peer = rxrpc_lookup_peer_local_rcu(local, skb, &srx);
149 if (peer && !rxrpc_get_peer_maybe(peer, rxrpc_peer_get_input_error))
150 peer = NULL;
151 rcu_read_unlock();
152 if (!peer)
153 return;
154
155 trace_rxrpc_rx_icmp(peer, &serr->ee, &srx);
156
157 if ((serr->ee.ee_origin == SO_EE_ORIGIN_ICMP &&
158 serr->ee.ee_type == ICMP_DEST_UNREACH &&
159 serr->ee.ee_code == ICMP_FRAG_NEEDED)) {
160 rxrpc_adjust_mtu(peer, serr->ee.ee_info);
161 goto out;
162 }
163
164 rxrpc_store_error(peer, skb);
165out:
166 rxrpc_put_peer(peer, rxrpc_peer_put_input_error);
167}
168
169/*
170 * Map an error report to error codes on the peer record.
171 */
172static void rxrpc_store_error(struct rxrpc_peer *peer, struct sk_buff *skb)
173{
174 enum rxrpc_call_completion compl = RXRPC_CALL_NETWORK_ERROR;
175 struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
176 struct sock_extended_err *ee = &serr->ee;
177 int err = ee->ee_errno;
178
179 _enter("");
180
181 switch (ee->ee_origin) {
182 case SO_EE_ORIGIN_NONE:
183 case SO_EE_ORIGIN_LOCAL:
184 compl = RXRPC_CALL_LOCAL_ERROR;
185 break;
186
187 case SO_EE_ORIGIN_ICMP6:
188 if (err == EACCES)
189 err = EHOSTUNREACH;
190 fallthrough;
191 case SO_EE_ORIGIN_ICMP:
192 default:
193 break;
194 }
195
196 rxrpc_distribute_error(peer, skb, compl, err);
197}
198
199/*
200 * Distribute an error that occurred on a peer.
201 */
202static void rxrpc_distribute_error(struct rxrpc_peer *peer, struct sk_buff *skb,
203 enum rxrpc_call_completion compl, int err)
204{
205 struct rxrpc_call *call;
206 HLIST_HEAD(error_targets);
207
208 spin_lock(&peer->lock);
209 hlist_move_list(&peer->error_targets, &error_targets);
210
211 while (!hlist_empty(&error_targets)) {
212 call = hlist_entry(error_targets.first,
213 struct rxrpc_call, error_link);
214 hlist_del_init(&call->error_link);
215 spin_unlock(&peer->lock);
216
217 rxrpc_see_call(call, rxrpc_call_see_distribute_error);
218 rxrpc_set_call_completion(call, compl, 0, -err);
219 rxrpc_input_call_event(call, skb);
220
221 spin_lock(&peer->lock);
222 }
223
224 spin_unlock(&peer->lock);
225}
226
227/*
228 * Perform keep-alive pings.
229 */
230static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet,
231 struct list_head *collector,
232 time64_t base,
233 u8 cursor)
234{
235 struct rxrpc_peer *peer;
236 const u8 mask = ARRAY_SIZE(rxnet->peer_keepalive) - 1;
237 time64_t keepalive_at;
238 bool use;
239 int slot;
240
241 spin_lock(&rxnet->peer_hash_lock);
242
243 while (!list_empty(collector)) {
244 peer = list_entry(collector->next,
245 struct rxrpc_peer, keepalive_link);
246
247 list_del_init(&peer->keepalive_link);
248 if (!rxrpc_get_peer_maybe(peer, rxrpc_peer_get_keepalive))
249 continue;
250
251 use = __rxrpc_use_local(peer->local, rxrpc_local_use_peer_keepalive);
252 spin_unlock(&rxnet->peer_hash_lock);
253
254 if (use) {
255 keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME;
256 slot = keepalive_at - base;
257 _debug("%02x peer %u t=%d {%pISp}",
258 cursor, peer->debug_id, slot, &peer->srx.transport);
259
260 if (keepalive_at <= base ||
261 keepalive_at > base + RXRPC_KEEPALIVE_TIME) {
262 rxrpc_send_keepalive(peer);
263 slot = RXRPC_KEEPALIVE_TIME;
264 }
265
266 /* A transmission to this peer occurred since last we
267 * examined it so put it into the appropriate future
268 * bucket.
269 */
270 slot += cursor;
271 slot &= mask;
272 spin_lock(&rxnet->peer_hash_lock);
273 list_add_tail(&peer->keepalive_link,
274 &rxnet->peer_keepalive[slot & mask]);
275 spin_unlock(&rxnet->peer_hash_lock);
276 rxrpc_unuse_local(peer->local, rxrpc_local_unuse_peer_keepalive);
277 }
278 rxrpc_put_peer(peer, rxrpc_peer_put_keepalive);
279 spin_lock(&rxnet->peer_hash_lock);
280 }
281
282 spin_unlock(&rxnet->peer_hash_lock);
283}
284
285/*
286 * Perform keep-alive pings with VERSION packets to keep any NAT alive.
287 */
288void rxrpc_peer_keepalive_worker(struct work_struct *work)
289{
290 struct rxrpc_net *rxnet =
291 container_of(work, struct rxrpc_net, peer_keepalive_work);
292 const u8 mask = ARRAY_SIZE(rxnet->peer_keepalive) - 1;
293 time64_t base, now, delay;
294 u8 cursor, stop;
295 LIST_HEAD(collector);
296
297 now = ktime_get_seconds();
298 base = rxnet->peer_keepalive_base;
299 cursor = rxnet->peer_keepalive_cursor;
300 _enter("%lld,%u", base - now, cursor);
301
302 if (!rxnet->live)
303 return;
304
305 /* Remove to a temporary list all the peers that are currently lodged
306 * in expired buckets plus all new peers.
307 *
308 * Everything in the bucket at the cursor is processed this
309 * second; the bucket at cursor + 1 goes at now + 1s and so
310 * on...
311 */
312 spin_lock(&rxnet->peer_hash_lock);
313 list_splice_init(&rxnet->peer_keepalive_new, &collector);
314
315 stop = cursor + ARRAY_SIZE(rxnet->peer_keepalive);
316 while (base <= now && (s8)(cursor - stop) < 0) {
317 list_splice_tail_init(&rxnet->peer_keepalive[cursor & mask],
318 &collector);
319 base++;
320 cursor++;
321 }
322
323 base = now;
324 spin_unlock(&rxnet->peer_hash_lock);
325
326 rxnet->peer_keepalive_base = base;
327 rxnet->peer_keepalive_cursor = cursor;
328 rxrpc_peer_keepalive_dispatch(rxnet, &collector, base, cursor);
329 ASSERT(list_empty(&collector));
330
331 /* Schedule the timer for the next occupied timeslot. */
332 cursor = rxnet->peer_keepalive_cursor;
333 stop = cursor + RXRPC_KEEPALIVE_TIME - 1;
334 for (; (s8)(cursor - stop) < 0; cursor++) {
335 if (!list_empty(&rxnet->peer_keepalive[cursor & mask]))
336 break;
337 base++;
338 }
339
340 now = ktime_get_seconds();
341 delay = base - now;
342 if (delay < 1)
343 delay = 1;
344 delay *= HZ;
345 if (rxnet->live)
346 timer_reduce(&rxnet->peer_keepalive_timer, jiffies + delay);
347
348 _leave("");
349}