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 <[email protected]>
   7  *
   8  *  Authors:
   9  *      Roopa Prabhu <[email protected]>
  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,
  92                           struct netdev_nested_priv *priv)
  93 {
  94         __be32 ip = *(__be32 *)priv->data;
  95         struct in_device *in_dev;
  96         __be32 addr = 0;
  97
  98         in_dev = __in_dev_get_rcu(dev);
  99         if (in_dev)
 100                 addr = inet_confirm_addr(dev_net(dev), in_dev, 0, ip,
 101                                          RT_SCOPE_HOST);
 102
 103         if (addr == ip)
 104                 return 1;
 105
 106         return 0;
 107 }
 108
 109 static bool br_is_local_ip(struct net_device *dev, __be32 ip)
 110 {
 111         struct netdev_nested_priv priv = {
 112                 .data = (void *)&ip,
 113         };
 114
 115         if (br_chk_addr_ip(dev, &priv))
 116                 return true;
 117
 118         /* check if ip is configured on upper dev */
 119         if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip, &priv))
 120                 return true;
 121
 122         return false;
 123 }
 124
 125 void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
 126                               u16 vid, struct net_bridge_port *p)
 127 {
 128         struct net_device *dev = br->dev;
 129         struct net_device *vlandev = dev;
 130         struct neighbour *n;
 131         struct arphdr *parp;
 132         u8 *arpptr, *sha;
 133         __be32 sip, tip;
 134
 135         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
 136
 137         if ((dev->flags & IFF_NOARP) ||
 138             !pskb_may_pull(skb, arp_hdr_len(dev)))
 139                 return;
 140
 141         parp = arp_hdr(skb);
 142
 143         if (parp->ar_pro != htons(ETH_P_IP) ||
 144             parp->ar_hln != dev->addr_len ||
 145             parp->ar_pln != 4)
 146                 return;
 147
 148         arpptr = (u8 *)parp + sizeof(struct arphdr);
 149         sha = arpptr;
 150         arpptr += dev->addr_len;        /* sha */
 151         memcpy(&sip, arpptr, sizeof(sip));
 152         arpptr += sizeof(sip);
 153         arpptr += dev->addr_len;        /* tha */
 154         memcpy(&tip, arpptr, sizeof(tip));
 155
 156         if (ipv4_is_loopback(tip) ||
 157             ipv4_is_multicast(tip))
 158                 return;
 159
 160         if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED)) {
 161                 if (p && (p->flags & BR_NEIGH_SUPPRESS))
 162                         return;
 163                 if (parp->ar_op != htons(ARPOP_RREQUEST) &&
 164                     parp->ar_op != htons(ARPOP_RREPLY) &&
 165                     (ipv4_is_zeronet(sip) || sip == tip)) {
 166                         /* prevent flooding to neigh suppress ports */
 167                         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 168                         return;
 169                 }
 170         }
 171
 172         if (parp->ar_op != htons(ARPOP_REQUEST))
 173                 return;
 174
 175         if (vid != 0) {
 176                 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
 177                                                    vid);
 178                 if (!vlandev)
 179                         return;
 180         }
 181
 182         if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
 183             br_is_local_ip(vlandev, tip)) {
 184                 /* its our local ip, so don't proxy reply
 185                  * and don't forward to neigh suppress ports
 186                  */
 187                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 188                 return;
 189         }
 190
 191         n = neigh_lookup(&arp_tbl, &tip, vlandev);
 192         if (n) {
 193                 struct net_bridge_fdb_entry *f;
 194
 195                 if (!(n->nud_state & NUD_VALID)) {
 196                         neigh_release(n);
 197                         return;
 198                 }
 199
 200                 f = br_fdb_find_rcu(br, n->ha, vid);
 201                 if (f) {
 202                         bool replied = false;
 203
 204                         if ((p && (p->flags & BR_PROXYARP)) ||
 205                             (f->dst && (f->dst->flags & (BR_PROXYARP_WIFI |
 206                                                          BR_NEIGH_SUPPRESS)))) {
 207                                 if (!vid)
 208                                         br_arp_send(br, p, skb->dev, sip, tip,
 209                                                     sha, n->ha, sha, 0, 0);
 210                                 else
 211                                         br_arp_send(br, p, skb->dev, sip, tip,
 212                                                     sha, n->ha, sha,
 213                                                     skb->vlan_proto,
 214                                                     skb_vlan_tag_get(skb));
 215                                 replied = true;
 216                         }
 217
 218                         /* If we have replied or as long as we know the
 219                          * mac, indicate to arp replied
 220                          */
 221                         if (replied ||
 222                             br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
 223                                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 224                 }
 225
 226                 neigh_release(n);
 227         }
 228 }
 229 #endif
 230
 231 #if IS_ENABLED(CONFIG_IPV6)
 232 struct nd_msg *br_is_nd_neigh_msg(struct sk_buff *skb, struct nd_msg *msg)
 233 {
 234         struct nd_msg *m;
 235
 236         m = skb_header_pointer(skb, skb_network_offset(skb) +
 237                                sizeof(struct ipv6hdr), sizeof(*msg), msg);
 238         if (!m)
 239                 return NULL;
 240
 241         if (m->icmph.icmp6_code != 0 ||
 242             (m->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION &&
 243              m->icmph.icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT))
 244                 return NULL;
 245
 246         return m;
 247 }
 248
 249 static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p,
 250                        struct sk_buff *request, struct neighbour *n,
 251                        __be16 vlan_proto, u16 vlan_tci, struct nd_msg *ns)
 252 {
 253         struct net_device *dev = request->dev;
 254         struct net_bridge_vlan_group *vg;
 255         struct sk_buff *reply;
 256         struct nd_msg *na;
 257         struct ipv6hdr *pip6;
 258         int na_olen = 8; /* opt hdr + ETH_ALEN for target */
 259         int ns_olen;
 260         int i, len;
 261         u8 *daddr;
 262         u16 pvid;
 263
 264         if (!dev)
 265                 return;
 266
 267         len = LL_RESERVED_SPACE(dev) + sizeof(struct ipv6hdr) +
 268                 sizeof(*na) + na_olen + dev->needed_tailroom;
 269
 270         reply = alloc_skb(len, GFP_ATOMIC);
 271         if (!reply)
 272                 return;
 273
 274         reply->protocol = htons(ETH_P_IPV6);
 275         reply->dev = dev;
 276         skb_reserve(reply, LL_RESERVED_SPACE(dev));
 277         skb_push(reply, sizeof(struct ethhdr));
 278         skb_set_mac_header(reply, 0);
 279
 280         daddr = eth_hdr(request)->h_source;
 281
 282         /* Do we need option processing ? */
 283         ns_olen = request->len - (skb_network_offset(request) +
 284                                   sizeof(struct ipv6hdr)) - sizeof(*ns);
 285         for (i = 0; i < ns_olen - 1; i += (ns->opt[i + 1] << 3)) {
 286                 if (!ns->opt[i + 1]) {
 287                         kfree_skb(reply);
 288                         return;
 289                 }
 290                 if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) {
 291                         daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
 292                         break;
 293                 }
 294         }
 295
 296         /* Ethernet header */
 297         ether_addr_copy(eth_hdr(reply)->h_dest, daddr);
 298         ether_addr_copy(eth_hdr(reply)->h_source, n->ha);
 299         eth_hdr(reply)->h_proto = htons(ETH_P_IPV6);
 300         reply->protocol = htons(ETH_P_IPV6);
 301
 302         skb_pull(reply, sizeof(struct ethhdr));
 303         skb_set_network_header(reply, 0);
 304         skb_put(reply, sizeof(struct ipv6hdr));
 305
 306         /* IPv6 header */
 307         pip6 = ipv6_hdr(reply);
 308         memset(pip6, 0, sizeof(struct ipv6hdr));
 309         pip6->version = 6;
 310         pip6->priority = ipv6_hdr(request)->priority;
 311         pip6->nexthdr = IPPROTO_ICMPV6;
 312         pip6->hop_limit = 255;
 313         pip6->daddr = ipv6_hdr(request)->saddr;
 314         pip6->saddr = *(struct in6_addr *)n->primary_key;
 315
 316         skb_pull(reply, sizeof(struct ipv6hdr));
 317         skb_set_transport_header(reply, 0);
 318
 319         na = (struct nd_msg *)skb_put(reply, sizeof(*na) + na_olen);
 320
 321         /* Neighbor Advertisement */
 322         memset(na, 0, sizeof(*na) + na_olen);
 323         na->icmph.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
 324         na->icmph.icmp6_router = (n->flags & NTF_ROUTER) ? 1 : 0;
 325         na->icmph.icmp6_override = 1;
 326         na->icmph.icmp6_solicited = 1;
 327         na->target = ns->target;
 328         ether_addr_copy(&na->opt[2], n->ha);
 329         na->opt[0] = ND_OPT_TARGET_LL_ADDR;
 330         na->opt[1] = na_olen >> 3;
 331
 332         na->icmph.icmp6_cksum = csum_ipv6_magic(&pip6->saddr,
 333                                                 &pip6->daddr,
 334                                                 sizeof(*na) + na_olen,
 335                                                 IPPROTO_ICMPV6,
 336                                                 csum_partial(na, sizeof(*na) + na_olen, 0));
 337
 338         pip6->payload_len = htons(sizeof(*na) + na_olen);
 339
 340         skb_push(reply, sizeof(struct ipv6hdr));
 341         skb_push(reply, sizeof(struct ethhdr));
 342
 343         reply->ip_summed = CHECKSUM_UNNECESSARY;
 344
 345         if (p)
 346                 vg = nbp_vlan_group_rcu(p);
 347         else
 348                 vg = br_vlan_group_rcu(br);
 349         pvid = br_get_pvid(vg);
 350         if (pvid == (vlan_tci & VLAN_VID_MASK))
 351                 vlan_tci = 0;
 352
 353         if (vlan_tci)
 354                 __vlan_hwaccel_put_tag(reply, vlan_proto, vlan_tci);
 355
 356         netdev_dbg(dev, "nd send dev %s dst %pI6 dst_hw %pM src %pI6 src_hw %pM\n",
 357                    dev->name, &pip6->daddr, daddr, &pip6->saddr, n->ha);
 358
 359         if (p) {
 360                 dev_queue_xmit(reply);
 361         } else {
 362                 skb_reset_mac_header(reply);
 363                 __skb_pull(reply, skb_network_offset(reply));
 364                 reply->ip_summed = CHECKSUM_UNNECESSARY;
 365                 reply->pkt_type = PACKET_HOST;
 366
 367                 netif_rx_ni(reply);
 368         }
 369 }
 370
 371 static int br_chk_addr_ip6(struct net_device *dev,
 372                            struct netdev_nested_priv *priv)
 373 {
 374         struct in6_addr *addr = (struct in6_addr *)priv->data;
 375
 376         if (ipv6_chk_addr(dev_net(dev), addr, dev, 0))
 377                 return 1;
 378
 379         return 0;
 380 }
 381
 382 static bool br_is_local_ip6(struct net_device *dev, struct in6_addr *addr)
 383
 384 {
 385         struct netdev_nested_priv priv = {
 386                 .data = (void *)addr,
 387         };
 388
 389         if (br_chk_addr_ip6(dev, &priv))
 390                 return true;
 391
 392         /* check if ip is configured on upper dev */
 393         if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip6, &priv))
 394                 return true;
 395
 396         return false;
 397 }
 398
 399 void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
 400                        u16 vid, struct net_bridge_port *p, struct nd_msg *msg)
 401 {
 402         struct net_device *dev = br->dev;
 403         struct net_device *vlandev = NULL;
 404         struct in6_addr *saddr, *daddr;
 405         struct ipv6hdr *iphdr;
 406         struct neighbour *n;
 407
 408         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
 409
 410         if (p && (p->flags & BR_NEIGH_SUPPRESS))
 411                 return;
 412
 413         if (msg->icmph.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT &&
 414             !msg->icmph.icmp6_solicited) {
 415                 /* prevent flooding to neigh suppress ports */
 416                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 417                 return;
 418         }
 419
 420         if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
 421                 return;
 422
 423         iphdr = ipv6_hdr(skb);
 424         saddr = &iphdr->saddr;
 425         daddr = &iphdr->daddr;
 426
 427         if (ipv6_addr_any(saddr) || !ipv6_addr_cmp(saddr, daddr)) {
 428                 /* prevent flooding to neigh suppress ports */
 429                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 430                 return;
 431         }
 432
 433         if (vid != 0) {
 434                 /* build neigh table lookup on the vlan device */
 435                 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
 436                                                    vid);
 437                 if (!vlandev)
 438                         return;
 439         } else {
 440                 vlandev = dev;
 441         }
 442
 443         if (br_is_local_ip6(vlandev, &msg->target)) {
 444                 /* its our own ip, so don't proxy reply
 445                  * and don't forward to arp suppress ports
 446                  */
 447                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 448                 return;
 449         }
 450
 451         n = neigh_lookup(ipv6_stub->nd_tbl, &msg->target, vlandev);
 452         if (n) {
 453                 struct net_bridge_fdb_entry *f;
 454
 455                 if (!(n->nud_state & NUD_VALID)) {
 456                         neigh_release(n);
 457                         return;
 458                 }
 459
 460                 f = br_fdb_find_rcu(br, n->ha, vid);
 461                 if (f) {
 462                         bool replied = false;
 463
 464                         if (f->dst && (f->dst->flags & BR_NEIGH_SUPPRESS)) {
 465                                 if (vid != 0)
 466                                         br_nd_send(br, p, skb, n,
 467                                                    skb->vlan_proto,
 468                                                    skb_vlan_tag_get(skb), msg);
 469                                 else
 470                                         br_nd_send(br, p, skb, n, 0, 0, msg);
 471                                 replied = true;
 472                         }
 473
 474                         /* If we have replied or as long as we know the
 475                          * mac, indicate to NEIGH_SUPPRESS ports that we
 476                          * have replied
 477                          */
 478                         if (replied ||
 479                             br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
 480                                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 481                 }
 482                 neigh_release(n);
 483         }
 484 }
 485 #endif