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  
21  static void rxrpc_store_error(struct rxrpc_peer *, struct sk_buff *);
22  static 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   */
rxrpc_lookup_peer_local_rcu(struct rxrpc_local * local,const struct sk_buff * skb,struct sockaddr_rxrpc * srx)28  static 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   */
rxrpc_adjust_mtu(struct rxrpc_peer * peer,unsigned int mtu)103  static 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   */
rxrpc_input_error(struct rxrpc_local * local,struct sk_buff * skb)134  void 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);
165  out:
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   */
rxrpc_store_error(struct rxrpc_peer * peer,struct sk_buff * skb)172  static 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   */
rxrpc_distribute_error(struct rxrpc_peer * peer,struct sk_buff * skb,enum rxrpc_call_completion compl,int err)202  static 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   */
rxrpc_peer_keepalive_dispatch(struct rxrpc_net * rxnet,struct list_head * collector,time64_t base,u8 cursor)230  static 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   */
rxrpc_peer_keepalive_worker(struct work_struct * work)288  void 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  }
350