net/bridge/br_arp_nd_proxy.c

   1 /*
   2  *  Handle bridge arp/nd proxy/suppress
   3  *
   4  *  Copyright (C) 2017 Cumulus Networks
   5  *  Copyright (c) 2017 Roopa Prabhu <roopa@cumulusnetworks.com>
   6  *
   7  *  Authors:
   8  *      Roopa Prabhu <roopa@cumulusnetworks.com>
   9  *
  10  *  This program is free software; you can redistribute it and/or
  11  *  modify it under the terms of the GNU General Public License
  12  *  as published by the Free Software Foundation; either version
  13  *  2 of the License, or (at your option) any later version.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/etherdevice.h>
  19 #include <linux/neighbour.h>
  20 #include <net/arp.h>
  21 #include <linux/if_vlan.h>
  22 #include <linux/inetdevice.h>
  23 #include <net/addrconf.h>
  24 #if IS_ENABLED(CONFIG_IPV6)
  25 #include <net/ip6_checksum.h>
  26 #endif
  27
  28 #include "br_private.h"
  29
  30 void br_recalculate_neigh_suppress_enabled(struct net_bridge *br)
  31 {
  32         struct net_bridge_port *p;
  33         bool neigh_suppress = false;
  34
  35         list_for_each_entry(p, &br->port_list, list) {
  36                 if (p->flags & BR_NEIGH_SUPPRESS) {
  37                         neigh_suppress = true;
  38                         break;
  39                 }
  40         }
  41
  42         br->neigh_suppress_enabled = neigh_suppress;
  43 }
  44
  45 #if IS_ENABLED(CONFIG_INET)
  46 static void br_arp_send(struct net_bridge *br, struct net_bridge_port *p,
  47                         struct net_device *dev, __be32 dest_ip, __be32 src_ip,
  48                         const unsigned char *dest_hw,
  49                         const unsigned char *src_hw,
  50                         const unsigned char *target_hw,
  51                         __be16 vlan_proto, u16 vlan_tci)
  52 {
  53         struct net_bridge_vlan_group *vg;
  54         struct sk_buff *skb;
  55         u16 pvid;
  56
  57         netdev_dbg(dev, "arp send dev %s dst %pI4 dst_hw %pM src %pI4 src_hw %pM\n",
  58                    dev->name, &dest_ip, dest_hw, &src_ip, src_hw);
  59
  60         if (!vlan_tci) {
  61                 arp_send(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
  62                          dest_hw, src_hw, target_hw);
  63                 return;
  64         }
  65
  66         skb = arp_create(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
  67                          dest_hw, src_hw, target_hw);
  68         if (!skb)
  69                 return;
  70
  71         if (p)
  72                 vg = nbp_vlan_group_rcu(p);
  73         else
  74                 vg = br_vlan_group_rcu(br);
  75         pvid = br_get_pvid(vg);
  76         if (pvid == (vlan_tci & VLAN_VID_MASK))
  77                 vlan_tci = 0;
  78
  79         if (vlan_tci)
  80                 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
  81
  82         if (p) {
  83                 arp_xmit(skb);
  84         } else {
  85                 skb_reset_mac_header(skb);
  86                 __skb_pull(skb, skb_network_offset(skb));
  87                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  88                 skb->pkt_type = PACKET_HOST;
  89
  90                 netif_rx_ni(skb);
  91         }
  92 }
  93
  94 static int br_chk_addr_ip(struct net_device *dev, void *data)
  95 {
  96         __be32 ip = *(__be32 *)data;
  97         struct in_device *in_dev;
  98         __be32 addr = 0;
  99
 100         in_dev = __in_dev_get_rcu(dev);
 101         if (in_dev)
 102                 addr = inet_confirm_addr(dev_net(dev), in_dev, 0, ip,
 103                                          RT_SCOPE_HOST);
 104
 105         if (addr == ip)
 106                 return 1;
 107
 108         return 0;
 109 }
 110
 111 static bool br_is_local_ip(struct net_device *dev, __be32 ip)
 112 {
 113         if (br_chk_addr_ip(dev, &ip))
 114                 return true;
 115
 116         /* check if ip is configured on upper dev */
 117         if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip, &ip))
 118                 return true;
 119
 120         return false;
 121 }
 122
 123 void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
 124                               u16 vid, struct net_bridge_port *p)
 125 {
 126         struct net_device *dev = br->dev;
 127         struct net_device *vlandev = dev;
 128         struct neighbour *n;
 129         struct arphdr *parp;
 130         u8 *arpptr, *sha;
 131         __be32 sip, tip;
 132
 133         BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
 134
 135         if ((dev->flags & IFF_NOARP) ||
 136             !pskb_may_pull(skb, arp_hdr_len(dev)))
 137                 return;
 138
 139         parp = arp_hdr(skb);
 140
 141         if (parp->ar_pro != htons(ETH_P_IP) ||
 142             parp->ar_hln != dev->addr_len ||
 143             parp->ar_pln != 4)
 144                 return;
 145
 146         arpptr = (u8 *)parp + sizeof(struct arphdr);
 147         sha = arpptr;
 148         arpptr += dev->addr_len;        /* sha */
 149         memcpy(&sip, arpptr, sizeof(sip));
 150         arpptr += sizeof(sip);
 151         arpptr += dev->addr_len;        /* tha */
 152         memcpy(&tip, arpptr, sizeof(tip));
 153
 154         if (ipv4_is_loopback(tip) ||
 155             ipv4_is_multicast(tip))
 156                 return;
 157
 158         if (br->neigh_suppress_enabled) {
 159                 if (p && (p->flags & BR_NEIGH_SUPPRESS))
 160                         return;
 161                 if (parp->ar_op != htons(ARPOP_RREQUEST) &&
 162                     parp->ar_op != htons(ARPOP_RREPLY) &&
 163                     (ipv4_is_zeronet(sip) || sip == tip)) {
 164                         /* prevent flooding to neigh suppress ports */
 165                         BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
 166                         return;
 167                 }
 168         }
 169
 170         if (parp->ar_op != htons(ARPOP_REQUEST))
 171                 return;
 172
 173         if (vid != 0) {
 174                 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
 175                                                    vid);
 176                 if (!vlandev)
 177                         return;
 178         }
 179
 180         if (br->neigh_suppress_enabled && br_is_local_ip(vlandev, tip)) {
 181                 /* its our local ip, so don't proxy reply
 182                  * and don't forward to neigh suppress ports
 183                  */
 184                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
 185                 return;
 186         }
 187
 188         n = neigh_lookup(&arp_tbl, &tip, vlandev);
 189         if (n) {
 190                 struct net_bridge_fdb_entry *f;
 191
 192                 if (!(n->nud_state & NUD_VALID)) {
 193                         neigh_release(n);
 194                         return;
 195                 }
 196
 197                 f = br_fdb_find_rcu(br, n->ha, vid);
 198                 if (f) {
 199                         bool replied = false;
 200
 201                         if ((p && (p->flags & BR_PROXYARP)) ||
 202                             (f->dst && (f->dst->flags & (BR_PROXYARP_WIFI |
 203                                                          BR_NEIGH_SUPPRESS)))) {
 204                                 if (!vid)
 205                                         br_arp_send(br, p, skb->dev, sip, tip,
 206                                                     sha, n->ha, sha, 0, 0);
 207                                 else
 208                                         br_arp_send(br, p, skb->dev, sip, tip,
 209                                                     sha, n->ha, sha,
 210                                                     skb->vlan_proto,
 211                                                     skb_vlan_tag_get(skb));
 212                                 replied = true;
 213                         }
 214
 215                         /* If we have replied or as long as we know the
 216                          * mac, indicate to arp replied
 217                          */
 218                         if (replied || br->neigh_suppress_enabled)
 219                                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
 220                 }
 221
 222                 neigh_release(n);
 223         }
 224 }
 225 #endif
 226
 227 #if IS_ENABLED(CONFIG_IPV6)
 228 struct nd_msg *br_is_nd_neigh_msg(struct sk_buff *skb, struct nd_msg *msg)
 229 {
 230         struct nd_msg *m;
 231
 232         m = skb_header_pointer(skb, skb_network_offset(skb) +
 233                                sizeof(struct ipv6hdr), sizeof(*msg), msg);
 234         if (!m)
 235                 return NULL;
 236
 237         if (m->icmph.icmp6_code != 0 ||
 238             (m->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION &&
 239              m->icmph.icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT))
 240                 return NULL;
 241
 242         return m;
 243 }
 244
 245 static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p,
 246                        struct sk_buff *request, struct neighbour *n,
 247                        __be16 vlan_proto, u16 vlan_tci, struct nd_msg *ns)
 248 {
 249         struct net_device *dev = request->dev;
 250         struct net_bridge_vlan_group *vg;
 251         struct sk_buff *reply;
 252         struct nd_msg *na;
 253         struct ipv6hdr *pip6;
 254         int na_olen = 8; /* opt hdr + ETH_ALEN for target */
 255         int ns_olen;
 256         int i, len;
 257         u8 *daddr;
 258         u16 pvid;
 259
 260         if (!dev)
 261                 return;
 262
 263         len = LL_RESERVED_SPACE(dev) + sizeof(struct ipv6hdr) +
 264                 sizeof(*na) + na_olen + dev->needed_tailroom;
 265
 266         reply = alloc_skb(len, GFP_ATOMIC);
 267         if (!reply)
 268                 return;
 269
 270         reply->protocol = htons(ETH_P_IPV6);
 271         reply->dev = dev;
 272         skb_reserve(reply, LL_RESERVED_SPACE(dev));
 273         skb_push(reply, sizeof(struct ethhdr));
 274         skb_set_mac_header(reply, 0);
 275
 276         daddr = eth_hdr(request)->h_source;
 277
 278         /* Do we need option processing ? */
 279         ns_olen = request->len - (skb_network_offset(request) +
 280                                   sizeof(struct ipv6hdr)) - sizeof(*ns);
 281         for (i = 0; i < ns_olen - 1; i += (ns->opt[i + 1] << 3)) {
 282                 if (!ns->opt[i + 1]) {
 283                         kfree_skb(reply);
 284                         return;
 285                 }
 286                 if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) {
 287                         daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
 288                         break;
 289                 }
 290         }
 291
 292         /* Ethernet header */
 293         ether_addr_copy(eth_hdr(reply)->h_dest, daddr);
 294         ether_addr_copy(eth_hdr(reply)->h_source, n->ha);
 295         eth_hdr(reply)->h_proto = htons(ETH_P_IPV6);
 296         reply->protocol = htons(ETH_P_IPV6);
 297
 298         skb_pull(reply, sizeof(struct ethhdr));
 299         skb_set_network_header(reply, 0);
 300         skb_put(reply, sizeof(struct ipv6hdr));
 301
 302         /* IPv6 header */
 303         pip6 = ipv6_hdr(reply);
 304         memset(pip6, 0, sizeof(struct ipv6hdr));
 305         pip6->version = 6;
 306         pip6->priority = ipv6_hdr(request)->priority;
 307         pip6->nexthdr = IPPROTO_ICMPV6;
 308         pip6->hop_limit = 255;
 309         pip6->daddr = ipv6_hdr(request)->saddr;
 310         pip6->saddr = *(struct in6_addr *)n->primary_key;
 311
 312         skb_pull(reply, sizeof(struct ipv6hdr));
 313         skb_set_transport_header(reply, 0);
 314
 315         na = (struct nd_msg *)skb_put(reply, sizeof(*na) + na_olen);
 316
 317         /* Neighbor Advertisement */
 318         memset(na, 0, sizeof(*na) + na_olen);
 319         na->icmph.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
 320         na->icmph.icmp6_router = (n->flags & NTF_ROUTER) ? 1 : 0;
 321         na->icmph.icmp6_override = 1;
 322         na->icmph.icmp6_solicited = 1;
 323         na->target = ns->target;
 324         ether_addr_copy(&na->opt[2], n->ha);
 325         na->opt[0] = ND_OPT_TARGET_LL_ADDR;
 326         na->opt[1] = na_olen >> 3;
 327
 328         na->icmph.icmp6_cksum = csum_ipv6_magic(&pip6->saddr,
 329                                                 &pip6->daddr,
 330                                                 sizeof(*na) + na_olen,
 331                                                 IPPROTO_ICMPV6,
 332                                                 csum_partial(na, sizeof(*na) + na_olen, 0));
 333
 334         pip6->payload_len = htons(sizeof(*na) + na_olen);
 335
 336         skb_push(reply, sizeof(struct ipv6hdr));
 337         skb_push(reply, sizeof(struct ethhdr));
 338
 339         reply->ip_summed = CHECKSUM_UNNECESSARY;
 340
 341         if (p)
 342                 vg = nbp_vlan_group_rcu(p);
 343         else
 344                 vg = br_vlan_group_rcu(br);
 345         pvid = br_get_pvid(vg);
 346         if (pvid == (vlan_tci & VLAN_VID_MASK))
 347                 vlan_tci = 0;
 348
 349         if (vlan_tci)
 350                 __vlan_hwaccel_put_tag(reply, vlan_proto, vlan_tci);
 351
 352         netdev_dbg(dev, "nd send dev %s dst %pI6 dst_hw %pM src %pI6 src_hw %pM\n",
 353                    dev->name, &pip6->daddr, daddr, &pip6->saddr, n->ha);
 354
 355         if (p) {
 356                 dev_queue_xmit(reply);
 357         } else {
 358                 skb_reset_mac_header(reply);
 359                 __skb_pull(reply, skb_network_offset(reply));
 360                 reply->ip_summed = CHECKSUM_UNNECESSARY;
 361                 reply->pkt_type = PACKET_HOST;
 362
 363                 netif_rx_ni(reply);
 364         }
 365 }
 366
 367 static int br_chk_addr_ip6(struct net_device *dev, void *data)
 368 {
 369         struct in6_addr *addr = (struct in6_addr *)data;
 370
 371         if (ipv6_chk_addr(dev_net(dev), addr, dev, 0))
 372                 return 1;
 373
 374         return 0;
 375 }
 376
 377 static bool br_is_local_ip6(struct net_device *dev, struct in6_addr *addr)
 378
 379 {
 380         if (br_chk_addr_ip6(dev, addr))
 381                 return true;
 382
 383         /* check if ip is configured on upper dev */
 384         if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip6, addr))
 385                 return true;
 386
 387         return false;
 388 }
 389
 390 void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
 391                        u16 vid, struct net_bridge_port *p, struct nd_msg *msg)
 392 {
 393         struct net_device *dev = br->dev;
 394         struct net_device *vlandev = NULL;
 395         struct in6_addr *saddr, *daddr;
 396         struct ipv6hdr *iphdr;
 397         struct neighbour *n;
 398
 399         BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
 400
 401         if (p && (p->flags & BR_NEIGH_SUPPRESS))
 402                 return;
 403
 404         if (msg->icmph.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT &&
 405             !msg->icmph.icmp6_solicited) {
 406                 /* prevent flooding to neigh suppress ports */
 407                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
 408                 return;
 409         }
 410
 411         if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
 412                 return;
 413
 414         iphdr = ipv6_hdr(skb);
 415         saddr = &iphdr->saddr;
 416         daddr = &iphdr->daddr;
 417
 418         if (ipv6_addr_any(saddr) || !ipv6_addr_cmp(saddr, daddr)) {
 419                 /* prevent flooding to neigh suppress ports */
 420                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
 421                 return;
 422         }
 423
 424         if (vid != 0) {
 425                 /* build neigh table lookup on the vlan device */
 426                 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
 427                                                    vid);
 428                 if (!vlandev)
 429                         return;
 430         } else {
 431                 vlandev = dev;
 432         }
 433
 434         if (br_is_local_ip6(vlandev, &msg->target)) {
 435                 /* its our own ip, so don't proxy reply
 436                  * and don't forward to arp suppress ports
 437                  */
 438                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
 439                 return;
 440         }
 441
 442         n = neigh_lookup(ipv6_stub->nd_tbl, &msg->target, vlandev);
 443         if (n) {
 444                 struct net_bridge_fdb_entry *f;
 445
 446                 if (!(n->nud_state & NUD_VALID)) {
 447                         neigh_release(n);
 448                         return;
 449                 }
 450
 451                 f = br_fdb_find_rcu(br, n->ha, vid);
 452                 if (f) {
 453                         bool replied = false;
 454
 455                         if (f->dst && (f->dst->flags & BR_NEIGH_SUPPRESS)) {
 456                                 if (vid != 0)
 457                                         br_nd_send(br, p, skb, n,
 458                                                    skb->vlan_proto,
 459                                                    skb_vlan_tag_get(skb), msg);
 460                                 else
 461                                         br_nd_send(br, p, skb, n, 0, 0, msg);
 462                                 replied = true;
 463                         }
 464
 465                         /* If we have replied or as long as we know the
 466                          * mac, indicate to NEIGH_SUPPRESS ports that we
 467                          * have replied
 468                          */
 469                         if (replied || br->neigh_suppress_enabled)
 470                                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
 471                 }
 472                 neigh_release(n);
 473         }
 474 }
 475 #endif