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 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 }