net/bridge/br_arp_nd_proxy.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Handle bridge arp/nd proxy/suppress
   4  *
   5  *  Copyright (C) 2017 Cumulus Networks
   6  *  Copyright (c) 2017 Roopa Prabhu <roopa@cumulusnetworks.com>
   7  *
   8  *  Authors:
   9  *      Roopa Prabhu <roopa@cumulusnetworks.com>
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/netdevice.h>
  14 #include <linux/etherdevice.h>
  15 #include <linux/neighbour.h>
  16 #include <net/arp.h>
  17 #include <linux/if_vlan.h>
  18 #include <linux/inetdevice.h>
  19 #include <net/addrconf.h>
  20 #include <net/ipv6_stubs.h>
  21 #if IS_ENABLED(CONFIG_IPV6)
  22 #include <net/ip6_checksum.h>
  23 #endif
  24
  25 #include "br_private.h"
  26
  27 void br_recalculate_neigh_suppress_enabled(struct net_bridge *br)
  28 {
  29         struct net_bridge_port *p;
  30         bool neigh_suppress = false;
  31
  32         list_for_each_entry(p, &br->port_list, list) {
  33                 if (p->flags & BR_NEIGH_SUPPRESS) {
  34                         neigh_suppress = true;
  35                         break;
  36                 }
  37         }
  38
  39         br_opt_toggle(br, BROPT_NEIGH_SUPPRESS_ENABLED, neigh_suppress);
  40 }
  41
  42 #if IS_ENABLED(CONFIG_INET)
  43 static void br_arp_send(struct net_bridge *br, struct net_bridge_port *p,
  44                         struct net_device *dev, __be32 dest_ip, __be32 src_ip,
  45                         const unsigned char *dest_hw,
  46                         const unsigned char *src_hw,
  47                         const unsigned char *target_hw,
  48                         __be16 vlan_proto, u16 vlan_tci)
  49 {
  50         struct net_bridge_vlan_group *vg;
  51         struct sk_buff *skb;
  52         u16 pvid;
  53
  54         netdev_dbg(dev, "arp send dev %s dst %pI4 dst_hw %pM src %pI4 src_hw %pM\n",
  55                    dev->name, &dest_ip, dest_hw, &src_ip, src_hw);
  56
  57         if (!vlan_tci) {
  58                 arp_send(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
  59                          dest_hw, src_hw, target_hw);
  60                 return;
  61         }
  62
  63         skb = arp_create(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
  64                          dest_hw, src_hw, target_hw);
  65         if (!skb)
  66                 return;
  67
  68         if (p)
  69                 vg = nbp_vlan_group_rcu(p);
  70         else
  71                 vg = br_vlan_group_rcu(br);
  72         pvid = br_get_pvid(vg);
  73         if (pvid == (vlan_tci & VLAN_VID_MASK))
  74                 vlan_tci = 0;
  75
  76         if (vlan_tci)
  77                 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
  78
  79         if (p) {
  80                 arp_xmit(skb);
  81         } else {
  82                 skb_reset_mac_header(skb);
  83                 __skb_pull(skb, skb_network_offset(skb));
  84                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  85                 skb->pkt_type = PACKET_HOST;
  86
  87                 netif_rx_ni(skb);
  88         }
  89 }
  90
  91 static int br_chk_addr_ip(struct net_device *dev, void *data)
  92 {
  93         __be32 ip = *(__be32 *)data;
  94         struct in_device *in_dev;
  95         __be32 addr = 0;
  96
  97         in_dev = __in_dev_get_rcu(dev);
  98         if (in_dev)
  99                 addr = inet_confirm_addr(dev_net(dev), in_dev, 0, ip,
 100                                          RT_SCOPE_HOST);
 101
 102         if (addr == ip)
 103                 return 1;
 104
 105         return 0;
 106 }
 107
 108 static bool br_is_local_ip(struct net_device *dev, __be32 ip)
 109 {
 110         if (br_chk_addr_ip(dev, &ip))
 111                 return true;
 112
 113         /* check if ip is configured on upper dev */
 114         if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip, &ip))
 115                 return true;
 116
 117         return false;
 118 }
 119
 120 void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
 121                               u16 vid, struct net_bridge_port *p)
 122 {
 123         struct net_device *dev = br->dev;
 124         struct net_device *vlandev = dev;
 125         struct neighbour *n;
 126         struct arphdr *parp;
 127         u8 *arpptr, *sha;
 128         __be32 sip, tip;
 129
 130         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
 131
 132         if ((dev->flags & IFF_NOARP) ||
 133             !pskb_may_pull(skb, arp_hdr_len(dev)))
 134                 return;
 135
 136         parp = arp_hdr(skb);
 137
 138         if (parp->ar_pro != htons(ETH_P_IP) ||
 139             parp->ar_hln != dev->addr_len ||
 140             parp->ar_pln != 4)
 141                 return;
 142
 143         arpptr = (u8 *)parp + sizeof(struct arphdr);
 144         sha = arpptr;
 145         arpptr += dev->addr_len;        /* sha */
 146         memcpy(&sip, arpptr, sizeof(sip));
 147         arpptr += sizeof(sip);
 148         arpptr += dev->addr_len;        /* tha */
 149         memcpy(&tip, arpptr, sizeof(tip));
 150
 151         if (ipv4_is_loopback(tip) ||
 152             ipv4_is_multicast(tip))
 153                 return;
 154
 155         if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED)) {
 156                 if (p && (p->flags & BR_NEIGH_SUPPRESS))
 157                         return;
 158                 if (ipv4_is_zeronet(sip) || sip == tip) {
 159                         /* prevent flooding to neigh suppress ports */
 160                         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 161                         return;
 162                 }
 163         }
 164
 165         if (parp->ar_op != htons(ARPOP_REQUEST))
 166                 return;
 167
 168         if (vid != 0) {
 169                 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
 170                                                    vid);
 171                 if (!vlandev)
 172                         return;
 173         }
 174
 175         if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
 176             br_is_local_ip(vlandev, tip)) {
 177                 /* its our local ip, so don't proxy reply
 178                  * and don't forward to neigh suppress ports
 179                  */
 180                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 181                 return;
 182         }
 183
 184         n = neigh_lookup(&arp_tbl, &tip, vlandev);
 185         if (n) {
 186                 struct net_bridge_fdb_entry *f;
 187
 188                 if (!(n->nud_state & NUD_VALID)) {
 189                         neigh_release(n);
 190                         return;
 191                 }
 192
 193                 f = br_fdb_find_rcu(br, n->ha, vid);
 194                 if (f) {
 195                         bool replied = false;
 196
 197                         if ((p && (p->flags & BR_PROXYARP)) ||
 198                             (f->dst && (f->dst->flags & (BR_PROXYARP_WIFI |
 199                                                          BR_NEIGH_SUPPRESS)))) {
 200                                 if (!vid)
 201                                         br_arp_send(br, p, skb->dev, sip, tip,
 202                                                     sha, n->ha, sha, 0, 0);
 203                                 else
 204                                         br_arp_send(br, p, skb->dev, sip, tip,
 205                                                     sha, n->ha, sha,
 206                                                     skb->vlan_proto,
 207                                                     skb_vlan_tag_get(skb));
 208                                 replied = true;
 209                         }
 210
 211                         /* If we have replied or as long as we know the
 212                          * mac, indicate to arp replied
 213                          */
 214                         if (replied ||
 215                             br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
 216                                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 217                 }
 218
 219                 neigh_release(n);
 220         }
 221 }
 222 #endif
 223
 224 #if IS_ENABLED(CONFIG_IPV6)
 225 struct nd_msg *br_is_nd_neigh_msg(struct sk_buff *skb, struct nd_msg *msg)
 226 {
 227         struct nd_msg *m;
 228
 229         m = skb_header_pointer(skb, skb_network_offset(skb) +
 230                                sizeof(struct ipv6hdr), sizeof(*msg), msg);
 231         if (!m)
 232                 return NULL;
 233
 234         if (m->icmph.icmp6_code != 0 ||
 235             (m->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION &&
 236              m->icmph.icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT))
 237                 return NULL;
 238
 239         return m;
 240 }
 241
 242 static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p,
 243                        struct sk_buff *request, struct neighbour *n,
 244                        __be16 vlan_proto, u16 vlan_tci, struct nd_msg *ns)
 245 {
 246         struct net_device *dev = request->dev;
 247         struct net_bridge_vlan_group *vg;
 248         struct sk_buff *reply;
 249         struct nd_msg *na;
 250         struct ipv6hdr *pip6;
 251         int na_olen = 8; /* opt hdr + ETH_ALEN for target */
 252         int ns_olen;
 253         int i, len;
 254         u8 *daddr;
 255         u16 pvid;
 256
 257         if (!dev)
 258                 return;
 259
 260         len = LL_RESERVED_SPACE(dev) + sizeof(struct ipv6hdr) +
 261                 sizeof(*na) + na_olen + dev->needed_tailroom;
 262
 263         reply = alloc_skb(len, GFP_ATOMIC);
 264         if (!reply)
 265                 return;
 266
 267         reply->protocol = htons(ETH_P_IPV6);
 268         reply->dev = dev;
 269         skb_reserve(reply, LL_RESERVED_SPACE(dev));
 270         skb_push(reply, sizeof(struct ethhdr));
 271         skb_set_mac_header(reply, 0);
 272
 273         daddr = eth_hdr(request)->h_source;
 274
 275         /* Do we need option processing ? */
 276         ns_olen = request->len - (skb_network_offset(request) +
 277                                   sizeof(struct ipv6hdr)) - sizeof(*ns);
 278         for (i = 0; i < ns_olen - 1; i += (ns->opt[i + 1] << 3)) {
 279                 if (!ns->opt[i + 1]) {
 280                         kfree_skb(reply);
 281                         return;
 282                 }
 283                 if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) {
 284                         daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
 285                         break;
 286                 }
 287         }
 288
 289         /* Ethernet header */
 290         ether_addr_copy(eth_hdr(reply)->h_dest, daddr);
 291         ether_addr_copy(eth_hdr(reply)->h_source, n->ha);
 292         eth_hdr(reply)->h_proto = htons(ETH_P_IPV6);
 293         reply->protocol = htons(ETH_P_IPV6);
 294
 295         skb_pull(reply, sizeof(struct ethhdr));
 296         skb_set_network_header(reply, 0);
 297         skb_put(reply, sizeof(struct ipv6hdr));
 298
 299         /* IPv6 header */
 300         pip6 = ipv6_hdr(reply);
 301         memset(pip6, 0, sizeof(struct ipv6hdr));
 302         pip6->version = 6;
 303         pip6->priority = ipv6_hdr(request)->priority;
 304         pip6->nexthdr = IPPROTO_ICMPV6;
 305         pip6->hop_limit = 255;
 306         pip6->daddr = ipv6_hdr(request)->saddr;
 307         pip6->saddr = *(struct in6_addr *)n->primary_key;
 308
 309         skb_pull(reply, sizeof(struct ipv6hdr));
 310         skb_set_transport_header(reply, 0);
 311
 312         na = (struct nd_msg *)skb_put(reply, sizeof(*na) + na_olen);
 313
 314         /* Neighbor Advertisement */
 315         memset(na, 0, sizeof(*na) + na_olen);
 316         na->icmph.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
 317         na->icmph.icmp6_router = (n->flags & NTF_ROUTER) ? 1 : 0;
 318         na->icmph.icmp6_override = 1;
 319         na->icmph.icmp6_solicited = 1;
 320         na->target = ns->target;
 321         ether_addr_copy(&na->opt[2], n->ha);
 322         na->opt[0] = ND_OPT_TARGET_LL_ADDR;
 323         na->opt[1] = na_olen >> 3;
 324
 325         na->icmph.icmp6_cksum = csum_ipv6_magic(&pip6->saddr,
 326                                                 &pip6->daddr,
 327                                                 sizeof(*na) + na_olen,
 328                                                 IPPROTO_ICMPV6,
 329                                                 csum_partial(na, sizeof(*na) + na_olen, 0));
 330
 331         pip6->payload_len = htons(sizeof(*na) + na_olen);
 332
 333         skb_push(reply, sizeof(struct ipv6hdr));
 334         skb_push(reply, sizeof(struct ethhdr));
 335
 336         reply->ip_summed = CHECKSUM_UNNECESSARY;
 337
 338         if (p)
 339                 vg = nbp_vlan_group_rcu(p);
 340         else
 341                 vg = br_vlan_group_rcu(br);
 342         pvid = br_get_pvid(vg);
 343         if (pvid == (vlan_tci & VLAN_VID_MASK))
 344                 vlan_tci = 0;
 345
 346         if (vlan_tci)
 347                 __vlan_hwaccel_put_tag(reply, vlan_proto, vlan_tci);
 348
 349         netdev_dbg(dev, "nd send dev %s dst %pI6 dst_hw %pM src %pI6 src_hw %pM\n",
 350                    dev->name, &pip6->daddr, daddr, &pip6->saddr, n->ha);
 351
 352         if (p) {
 353                 dev_queue_xmit(reply);
 354         } else {
 355                 skb_reset_mac_header(reply);
 356                 __skb_pull(reply, skb_network_offset(reply));
 357                 reply->ip_summed = CHECKSUM_UNNECESSARY;
 358                 reply->pkt_type = PACKET_HOST;
 359
 360                 netif_rx_ni(reply);
 361         }
 362 }
 363
 364 static int br_chk_addr_ip6(struct net_device *dev, void *data)
 365 {
 366         struct in6_addr *addr = (struct in6_addr *)data;
 367
 368         if (ipv6_chk_addr(dev_net(dev), addr, dev, 0))
 369                 return 1;
 370
 371         return 0;
 372 }
 373
 374 static bool br_is_local_ip6(struct net_device *dev, struct in6_addr *addr)
 375
 376 {
 377         if (br_chk_addr_ip6(dev, addr))
 378                 return true;
 379
 380         /* check if ip is configured on upper dev */
 381         if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip6, addr))
 382                 return true;
 383
 384         return false;
 385 }
 386
 387 void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
 388                        u16 vid, struct net_bridge_port *p, struct nd_msg *msg)
 389 {
 390         struct net_device *dev = br->dev;
 391         struct net_device *vlandev = NULL;
 392         struct in6_addr *saddr, *daddr;
 393         struct ipv6hdr *iphdr;
 394         struct neighbour *n;
 395
 396         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
 397
 398         if (p && (p->flags & BR_NEIGH_SUPPRESS))
 399                 return;
 400
 401         if (msg->icmph.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT &&
 402             !msg->icmph.icmp6_solicited) {
 403                 /* prevent flooding to neigh suppress ports */
 404                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 405                 return;
 406         }
 407
 408         if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
 409                 return;
 410
 411         iphdr = ipv6_hdr(skb);
 412         saddr = &iphdr->saddr;
 413         daddr = &iphdr->daddr;
 414
 415         if (ipv6_addr_any(saddr) || !ipv6_addr_cmp(saddr, daddr)) {
 416                 /* prevent flooding to neigh suppress ports */
 417                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 418                 return;
 419         }
 420
 421         if (vid != 0) {
 422                 /* build neigh table lookup on the vlan device */
 423                 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
 424                                                    vid);
 425                 if (!vlandev)
 426                         return;
 427         } else {
 428                 vlandev = dev;
 429         }
 430
 431         if (br_is_local_ip6(vlandev, &msg->target)) {
 432                 /* its our own ip, so don't proxy reply
 433                  * and don't forward to arp suppress ports
 434                  */
 435                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 436                 return;
 437         }
 438
 439         n = neigh_lookup(ipv6_stub->nd_tbl, &msg->target, vlandev);
 440         if (n) {
 441                 struct net_bridge_fdb_entry *f;
 442
 443                 if (!(n->nud_state & NUD_VALID)) {
 444                         neigh_release(n);
 445                         return;
 446                 }
 447
 448                 f = br_fdb_find_rcu(br, n->ha, vid);
 449                 if (f) {
 450                         bool replied = false;
 451
 452                         if (f->dst && (f->dst->flags & BR_NEIGH_SUPPRESS)) {
 453                                 if (vid != 0)
 454                                         br_nd_send(br, p, skb, n,
 455                                                    skb->vlan_proto,
 456                                                    skb_vlan_tag_get(skb), msg);
 457                                 else
 458                                         br_nd_send(br, p, skb, n, 0, 0, msg);
 459                                 replied = true;
 460                         }
 461
 462                         /* If we have replied or as long as we know the
 463                          * mac, indicate to NEIGH_SUPPRESS ports that we
 464                          * have replied
 465                          */
 466                         if (replied ||
 467                             br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
 468                                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 469                 }
 470                 neigh_release(n);
 471         }
 472 }
 473 #endif