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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}