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 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  */
  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  */
 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  */
 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  */
 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  */
 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  */
 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         int slot;
 239
 240         spin_lock(&rxnet->peer_hash_lock);
 241
 242         while (!list_empty(collector)) {
 243                 peer = list_entry(collector->next,
 244                                   struct rxrpc_peer, keepalive_link);
 245
 246                 list_del_init(&peer->keepalive_link);
 247                 if (!rxrpc_get_peer_maybe(peer, rxrpc_peer_get_keepalive))
 248                         continue;
 249
 250                 if (__rxrpc_use_local(peer->local, rxrpc_local_use_peer_keepalive)) {
 251                         spin_unlock(&rxnet->peer_hash_lock);
 252
 253                         keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME;
 254                         slot = keepalive_at - base;
 255                         _debug("%02x peer %u t=%d {%pISp}",
 256                                cursor, peer->debug_id, slot, &peer->srx.transport);
 257
 258                         if (keepalive_at <= base ||
 259                             keepalive_at > base + RXRPC_KEEPALIVE_TIME) {
 260                                 rxrpc_send_keepalive(peer);
 261                                 slot = RXRPC_KEEPALIVE_TIME;
 262                         }
 263
 264                         /* A transmission to this peer occurred since last we
 265                          * examined it so put it into the appropriate future
 266                          * bucket.
 267                          */
 268                         slot += cursor;
 269                         slot &= mask;
 270                         spin_lock(&rxnet->peer_hash_lock);
 271                         list_add_tail(&peer->keepalive_link,
 272                                       &rxnet->peer_keepalive[slot & mask]);
 273                         rxrpc_unuse_local(peer->local, rxrpc_local_unuse_peer_keepalive);
 274                 }
 275                 rxrpc_put_peer_locked(peer, rxrpc_peer_put_keepalive);
 276         }
 277
 278         spin_unlock(&rxnet->peer_hash_lock);
 279 }
 280
 281 /*
 282  * Perform keep-alive pings with VERSION packets to keep any NAT alive.
 283  */
 284 void rxrpc_peer_keepalive_worker(struct work_struct *work)
 285 {
 286         struct rxrpc_net *rxnet =
 287                 container_of(work, struct rxrpc_net, peer_keepalive_work);
 288         const u8 mask = ARRAY_SIZE(rxnet->peer_keepalive) - 1;
 289         time64_t base, now, delay;
 290         u8 cursor, stop;
 291         LIST_HEAD(collector);
 292
 293         now = ktime_get_seconds();
 294         base = rxnet->peer_keepalive_base;
 295         cursor = rxnet->peer_keepalive_cursor;
 296         _enter("%lld,%u", base - now, cursor);
 297
 298         if (!rxnet->live)
 299                 return;
 300
 301         /* Remove to a temporary list all the peers that are currently lodged
 302          * in expired buckets plus all new peers.
 303          *
 304          * Everything in the bucket at the cursor is processed this
 305          * second; the bucket at cursor + 1 goes at now + 1s and so
 306          * on...
 307          */
 308         spin_lock(&rxnet->peer_hash_lock);
 309         list_splice_init(&rxnet->peer_keepalive_new, &collector);
 310
 311         stop = cursor + ARRAY_SIZE(rxnet->peer_keepalive);
 312         while (base <= now && (s8)(cursor - stop) < 0) {
 313                 list_splice_tail_init(&rxnet->peer_keepalive[cursor & mask],
 314                                       &collector);
 315                 base++;
 316                 cursor++;
 317         }
 318
 319         base = now;
 320         spin_unlock(&rxnet->peer_hash_lock);
 321
 322         rxnet->peer_keepalive_base = base;
 323         rxnet->peer_keepalive_cursor = cursor;
 324         rxrpc_peer_keepalive_dispatch(rxnet, &collector, base, cursor);
 325         ASSERT(list_empty(&collector));
 326
 327         /* Schedule the timer for the next occupied timeslot. */
 328         cursor = rxnet->peer_keepalive_cursor;
 329         stop = cursor + RXRPC_KEEPALIVE_TIME - 1;
 330         for (; (s8)(cursor - stop) < 0; cursor++) {
 331                 if (!list_empty(&rxnet->peer_keepalive[cursor & mask]))
 332                         break;
 333                 base++;
 334         }
 335
 336         now = ktime_get_seconds();
 337         delay = base - now;
 338         if (delay < 1)
 339                 delay = 1;
 340         delay *= HZ;
 341         if (rxnet->live)
 342                 timer_reduce(&rxnet->peer_keepalive_timer, jiffies + delay);
 343
 344         _leave("");
 345 }