net/rxrpc/peer_event.c

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