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Linux/net/rxrpc/peer_event.c

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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 
 21 static void rxrpc_store_error(struct rxrpc_peer *, struct sock_exterr_skb *);
 22 static void rxrpc_distribute_error(struct rxrpc_peer *, int,
 23                                    enum rxrpc_call_completion);
 24 
 25 /*
 26  * Find the peer associated with an ICMP packet.
 27  */
 28 static struct rxrpc_peer *rxrpc_lookup_peer_icmp_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                         _net("Rx ICMP");
 52                         memcpy(&srx->transport.sin.sin_addr,
 53                                skb_network_header(skb) + serr->addr_offset,
 54                                sizeof(struct in_addr));
 55                         break;
 56                 case SO_EE_ORIGIN_ICMP6:
 57                         _net("Rx ICMP6 on v4 sock");
 58                         memcpy(&srx->transport.sin.sin_addr,
 59                                skb_network_header(skb) + serr->addr_offset + 12,
 60                                sizeof(struct in_addr));
 61                         break;
 62                 default:
 63                         memcpy(&srx->transport.sin.sin_addr, &ip_hdr(skb)->saddr,
 64                                sizeof(struct in_addr));
 65                         break;
 66                 }
 67                 break;
 68 
 69 #ifdef CONFIG_AF_RXRPC_IPV6
 70         case AF_INET6:
 71                 switch (serr->ee.ee_origin) {
 72                 case SO_EE_ORIGIN_ICMP6:
 73                         _net("Rx ICMP6");
 74                         srx->transport.sin6.sin6_port = serr->port;
 75                         memcpy(&srx->transport.sin6.sin6_addr,
 76                                skb_network_header(skb) + serr->addr_offset,
 77                                sizeof(struct in6_addr));
 78                         break;
 79                 case SO_EE_ORIGIN_ICMP:
 80                         _net("Rx ICMP on v6 sock");
 81                         srx->transport_len = sizeof(srx->transport.sin);
 82                         srx->transport.family = AF_INET;
 83                         srx->transport.sin.sin_port = serr->port;
 84                         memcpy(&srx->transport.sin.sin_addr,
 85                                skb_network_header(skb) + serr->addr_offset,
 86                                sizeof(struct in_addr));
 87                         break;
 88                 default:
 89                         memcpy(&srx->transport.sin6.sin6_addr,
 90                                &ipv6_hdr(skb)->saddr,
 91                                sizeof(struct in6_addr));
 92                         break;
 93                 }
 94                 break;
 95 #endif
 96 
 97         default:
 98                 BUG();
 99         }
100 
101         return rxrpc_lookup_peer_rcu(local, srx);
102 }
103 
104 /*
105  * Handle an MTU/fragmentation problem.
106  */
107 static void rxrpc_adjust_mtu(struct rxrpc_peer *peer, struct sock_exterr_skb *serr)
108 {
109         u32 mtu = serr->ee.ee_info;
110 
111         _net("Rx ICMP Fragmentation Needed (%d)", mtu);
112 
113         /* wind down the local interface MTU */
114         if (mtu > 0 && peer->if_mtu == 65535 && mtu < peer->if_mtu) {
115                 peer->if_mtu = mtu;
116                 _net("I/F MTU %u", mtu);
117         }
118 
119         if (mtu == 0) {
120                 /* they didn't give us a size, estimate one */
121                 mtu = peer->if_mtu;
122                 if (mtu > 1500) {
123                         mtu >>= 1;
124                         if (mtu < 1500)
125                                 mtu = 1500;
126                 } else {
127                         mtu -= 100;
128                         if (mtu < peer->hdrsize)
129                                 mtu = peer->hdrsize + 4;
130                 }
131         }
132 
133         if (mtu < peer->mtu) {
134                 spin_lock_bh(&peer->lock);
135                 peer->mtu = mtu;
136                 peer->maxdata = peer->mtu - peer->hdrsize;
137                 spin_unlock_bh(&peer->lock);
138                 _net("Net MTU %u (maxdata %u)",
139                      peer->mtu, peer->maxdata);
140         }
141 }
142 
143 /*
144  * Handle an error received on the local endpoint.
145  */
146 void rxrpc_error_report(struct sock *sk)
147 {
148         struct sock_exterr_skb *serr;
149         struct sockaddr_rxrpc srx;
150         struct rxrpc_local *local;
151         struct rxrpc_peer *peer;
152         struct sk_buff *skb;
153 
154         rcu_read_lock();
155         local = rcu_dereference_sk_user_data(sk);
156         if (unlikely(!local)) {
157                 rcu_read_unlock();
158                 return;
159         }
160         _enter("%p{%d}", sk, local->debug_id);
161 
162         /* Clear the outstanding error value on the socket so that it doesn't
163          * cause kernel_sendmsg() to return it later.
164          */
165         sock_error(sk);
166 
167         skb = sock_dequeue_err_skb(sk);
168         if (!skb) {
169                 rcu_read_unlock();
170                 _leave("UDP socket errqueue empty");
171                 return;
172         }
173         rxrpc_new_skb(skb, rxrpc_skb_received);
174         serr = SKB_EXT_ERR(skb);
175         if (!skb->len && serr->ee.ee_origin == SO_EE_ORIGIN_TIMESTAMPING) {
176                 _leave("UDP empty message");
177                 rcu_read_unlock();
178                 rxrpc_free_skb(skb, rxrpc_skb_freed);
179                 return;
180         }
181 
182         peer = rxrpc_lookup_peer_icmp_rcu(local, skb, &srx);
183         if (peer && !rxrpc_get_peer_maybe(peer))
184                 peer = NULL;
185         if (!peer) {
186                 rcu_read_unlock();
187                 rxrpc_free_skb(skb, rxrpc_skb_freed);
188                 _leave(" [no peer]");
189                 return;
190         }
191 
192         trace_rxrpc_rx_icmp(peer, &serr->ee, &srx);
193 
194         if ((serr->ee.ee_origin == SO_EE_ORIGIN_ICMP &&
195              serr->ee.ee_type == ICMP_DEST_UNREACH &&
196              serr->ee.ee_code == ICMP_FRAG_NEEDED)) {
197                 rxrpc_adjust_mtu(peer, serr);
198                 rcu_read_unlock();
199                 rxrpc_free_skb(skb, rxrpc_skb_freed);
200                 rxrpc_put_peer(peer);
201                 _leave(" [MTU update]");
202                 return;
203         }
204 
205         rxrpc_store_error(peer, serr);
206         rcu_read_unlock();
207         rxrpc_free_skb(skb, rxrpc_skb_freed);
208         rxrpc_put_peer(peer);
209 
210         _leave("");
211 }
212 
213 /*
214  * Map an error report to error codes on the peer record.
215  */
216 static void rxrpc_store_error(struct rxrpc_peer *peer,
217                               struct sock_exterr_skb *serr)
218 {
219         enum rxrpc_call_completion compl = RXRPC_CALL_NETWORK_ERROR;
220         struct sock_extended_err *ee;
221         int err;
222 
223         _enter("");
224 
225         ee = &serr->ee;
226 
227         err = ee->ee_errno;
228 
229         switch (ee->ee_origin) {
230         case SO_EE_ORIGIN_ICMP:
231                 switch (ee->ee_type) {
232                 case ICMP_DEST_UNREACH:
233                         switch (ee->ee_code) {
234                         case ICMP_NET_UNREACH:
235                                 _net("Rx Received ICMP Network Unreachable");
236                                 break;
237                         case ICMP_HOST_UNREACH:
238                                 _net("Rx Received ICMP Host Unreachable");
239                                 break;
240                         case ICMP_PORT_UNREACH:
241                                 _net("Rx Received ICMP Port Unreachable");
242                                 break;
243                         case ICMP_NET_UNKNOWN:
244                                 _net("Rx Received ICMP Unknown Network");
245                                 break;
246                         case ICMP_HOST_UNKNOWN:
247                                 _net("Rx Received ICMP Unknown Host");
248                                 break;
249                         default:
250                                 _net("Rx Received ICMP DestUnreach code=%u",
251                                      ee->ee_code);
252                                 break;
253                         }
254                         break;
255 
256                 case ICMP_TIME_EXCEEDED:
257                         _net("Rx Received ICMP TTL Exceeded");
258                         break;
259 
260                 default:
261                         _proto("Rx Received ICMP error { type=%u code=%u }",
262                                ee->ee_type, ee->ee_code);
263                         break;
264                 }
265                 break;
266 
267         case SO_EE_ORIGIN_NONE:
268         case SO_EE_ORIGIN_LOCAL:
269                 _proto("Rx Received local error { error=%d }", err);
270                 compl = RXRPC_CALL_LOCAL_ERROR;
271                 break;
272 
273         case SO_EE_ORIGIN_ICMP6:
274                 if (err == EACCES)
275                         err = EHOSTUNREACH;
276                 fallthrough;
277         default:
278                 _proto("Rx Received error report { orig=%u }", ee->ee_origin);
279                 break;
280         }
281 
282         rxrpc_distribute_error(peer, err, compl);
283 }
284 
285 /*
286  * Distribute an error that occurred on a peer.
287  */
288 static void rxrpc_distribute_error(struct rxrpc_peer *peer, int error,
289                                    enum rxrpc_call_completion compl)
290 {
291         struct rxrpc_call *call;
292 
293         hlist_for_each_entry_rcu(call, &peer->error_targets, error_link) {
294                 rxrpc_see_call(call);
295                 rxrpc_set_call_completion(call, compl, 0, -error);
296         }
297 }
298 
299 /*
300  * Perform keep-alive pings.
301  */
302 static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet,
303                                           struct list_head *collector,
304                                           time64_t base,
305                                           u8 cursor)
306 {
307         struct rxrpc_peer *peer;
308         const u8 mask = ARRAY_SIZE(rxnet->peer_keepalive) - 1;
309         time64_t keepalive_at;
310         int slot;
311 
312         spin_lock_bh(&rxnet->peer_hash_lock);
313 
314         while (!list_empty(collector)) {
315                 peer = list_entry(collector->next,
316                                   struct rxrpc_peer, keepalive_link);
317 
318                 list_del_init(&peer->keepalive_link);
319                 if (!rxrpc_get_peer_maybe(peer))
320                         continue;
321 
322                 if (__rxrpc_use_local(peer->local)) {
323                         spin_unlock_bh(&rxnet->peer_hash_lock);
324 
325                         keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME;
326                         slot = keepalive_at - base;
327                         _debug("%02x peer %u t=%d {%pISp}",
328                                cursor, peer->debug_id, slot, &peer->srx.transport);
329 
330                         if (keepalive_at <= base ||
331                             keepalive_at > base + RXRPC_KEEPALIVE_TIME) {
332                                 rxrpc_send_keepalive(peer);
333                                 slot = RXRPC_KEEPALIVE_TIME;
334                         }
335 
336                         /* A transmission to this peer occurred since last we
337                          * examined it so put it into the appropriate future
338                          * bucket.
339                          */
340                         slot += cursor;
341                         slot &= mask;
342                         spin_lock_bh(&rxnet->peer_hash_lock);
343                         list_add_tail(&peer->keepalive_link,
344                                       &rxnet->peer_keepalive[slot & mask]);
345                         rxrpc_unuse_local(peer->local);
346                 }
347                 rxrpc_put_peer_locked(peer);
348         }
349 
350         spin_unlock_bh(&rxnet->peer_hash_lock);
351 }
352 
353 /*
354  * Perform keep-alive pings with VERSION packets to keep any NAT alive.
355  */
356 void rxrpc_peer_keepalive_worker(struct work_struct *work)
357 {
358         struct rxrpc_net *rxnet =
359                 container_of(work, struct rxrpc_net, peer_keepalive_work);
360         const u8 mask = ARRAY_SIZE(rxnet->peer_keepalive) - 1;
361         time64_t base, now, delay;
362         u8 cursor, stop;
363         LIST_HEAD(collector);
364 
365         now = ktime_get_seconds();
366         base = rxnet->peer_keepalive_base;
367         cursor = rxnet->peer_keepalive_cursor;
368         _enter("%lld,%u", base - now, cursor);
369 
370         if (!rxnet->live)
371                 return;
372 
373         /* Remove to a temporary list all the peers that are currently lodged
374          * in expired buckets plus all new peers.
375          *
376          * Everything in the bucket at the cursor is processed this
377          * second; the bucket at cursor + 1 goes at now + 1s and so
378          * on...
379          */
380         spin_lock_bh(&rxnet->peer_hash_lock);
381         list_splice_init(&rxnet->peer_keepalive_new, &collector);
382 
383         stop = cursor + ARRAY_SIZE(rxnet->peer_keepalive);
384         while (base <= now && (s8)(cursor - stop) < 0) {
385                 list_splice_tail_init(&rxnet->peer_keepalive[cursor & mask],
386                                       &collector);
387                 base++;
388                 cursor++;
389         }
390 
391         base = now;
392         spin_unlock_bh(&rxnet->peer_hash_lock);
393 
394         rxnet->peer_keepalive_base = base;
395         rxnet->peer_keepalive_cursor = cursor;
396         rxrpc_peer_keepalive_dispatch(rxnet, &collector, base, cursor);
397         ASSERT(list_empty(&collector));
398 
399         /* Schedule the timer for the next occupied timeslot. */
400         cursor = rxnet->peer_keepalive_cursor;
401         stop = cursor + RXRPC_KEEPALIVE_TIME - 1;
402         for (; (s8)(cursor - stop) < 0; cursor++) {
403                 if (!list_empty(&rxnet->peer_keepalive[cursor & mask]))
404                         break;
405                 base++;
406         }
407 
408         now = ktime_get_seconds();
409         delay = base - now;
410         if (delay < 1)
411                 delay = 1;
412         delay *= HZ;
413         if (rxnet->live)
414                 timer_reduce(&rxnet->peer_keepalive_timer, jiffies + delay);
415 
416         _leave("");
417 }
418 

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