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 #include <net/ipv6_stubs.h>
  25 #if IS_ENABLED(CONFIG_IPV6)
  26 #include <net/ip6_checksum.h>
  27 #endif
  28
  29 #include "br_private.h"
  30
  31 void br_recalculate_neigh_suppress_enabled(struct net_bridge *br)
  32 {
  33         struct net_bridge_port *p;
  34         bool neigh_suppress = false;
  35
  36         list_for_each_entry(p, &br->port_list, list) {
  37                 if (p->flags & BR_NEIGH_SUPPRESS) {
  38                         neigh_suppress = true;
  39                         break;
  40                 }
  41         }
  42
  43         br_opt_toggle(br, BROPT_NEIGH_SUPPRESS_ENABLED, neigh_suppress);
  44 }
  45
  46 #if IS_ENABLED(CONFIG_INET)
  47 static void br_arp_send(struct net_bridge *br, struct net_bridge_port *p,
  48                         struct net_device *dev, __be32 dest_ip, __be32 src_ip,
  49                         const unsigned char *dest_hw,
  50                         const unsigned char *src_hw,
  51                         const unsigned char *target_hw,
  52                         __be16 vlan_proto, u16 vlan_tci)
  53 {
  54         struct net_bridge_vlan_group *vg;
  55         struct sk_buff *skb;
  56         u16 pvid;
  57
  58         netdev_dbg(dev, "arp send dev %s dst %pI4 dst_hw %pM src %pI4 src_hw %pM\n",
  59                    dev->name, &dest_ip, dest_hw, &src_ip, src_hw);
  60
  61         if (!vlan_tci) {
  62                 arp_send(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
  63                          dest_hw, src_hw, target_hw);
  64                 return;
  65         }
  66
  67         skb = arp_create(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
  68                          dest_hw, src_hw, target_hw);
  69         if (!skb)
  70                 return;
  71
  72         if (p)
  73                 vg = nbp_vlan_group_rcu(p);
  74         else
  75                 vg = br_vlan_group_rcu(br);
  76         pvid = br_get_pvid(vg);
  77         if (pvid == (vlan_tci & VLAN_VID_MASK))
  78                 vlan_tci = 0;
  79
  80         if (vlan_tci)
  81                 __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
  82
  83         if (p) {
  84                 arp_xmit(skb);
  85         } else {
  86                 skb_reset_mac_header(skb);
  87                 __skb_pull(skb, skb_network_offset(skb));
  88                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  89                 skb->pkt_type = PACKET_HOST;
  90
  91                 netif_rx_ni(skb);
  92         }
  93 }
  94
  95 static int br_chk_addr_ip(struct net_device *dev, void *data)
  96 {
  97         __be32 ip = *(__be32 *)data;
  98         struct in_device *in_dev;
  99         __be32 addr = 0;
 100
 101         in_dev = __in_dev_get_rcu(dev);
 102         if (in_dev)
 103                 addr = inet_confirm_addr(dev_net(dev), in_dev, 0, ip,
 104                                          RT_SCOPE_HOST);
 105
 106         if (addr == ip)
 107                 return 1;
 108
 109         return 0;
 110 }
 111
 112 static bool br_is_local_ip(struct net_device *dev, __be32 ip)
 113 {
 114         if (br_chk_addr_ip(dev, &ip))
 115                 return true;
 116
 117         /* check if ip is configured on upper dev */
 118         if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip, &ip))
 119                 return true;
 120
 121         return false;
 122 }
 123
 124 void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
 125                               u16 vid, struct net_bridge_port *p)
 126 {
 127         struct net_device *dev = br->dev;
 128         struct net_device *vlandev = dev;
 129         struct neighbour *n;
 130         struct arphdr *parp;
 131         u8 *arpptr, *sha;
 132         __be32 sip, tip;
 133
 134         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
 135
 136         if ((dev->flags & IFF_NOARP) ||
 137             !pskb_may_pull(skb, arp_hdr_len(dev)))
 138                 return;
 139
 140         parp = arp_hdr(skb);
 141
 142         if (parp->ar_pro != htons(ETH_P_IP) ||
 143             parp->ar_hln != dev->addr_len ||
 144             parp->ar_pln != 4)
 145                 return;
 146
 147         arpptr = (u8 *)parp + sizeof(struct arphdr);
 148         sha = arpptr;
 149         arpptr += dev->addr_len;        /* sha */
 150         memcpy(&sip, arpptr, sizeof(sip));
 151         arpptr += sizeof(sip);
 152         arpptr += dev->addr_len;        /* tha */
 153         memcpy(&tip, arpptr, sizeof(tip));
 154
 155         if (ipv4_is_loopback(tip) ||
 156             ipv4_is_multicast(tip))
 157                 return;
 158
 159         if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED)) {
 160                 if (p && (p->flags & BR_NEIGH_SUPPRESS))
 161                         return;
 162                 if (ipv4_is_zeronet(sip) || sip == tip) {
 163                         /* prevent flooding to neigh suppress ports */
 164                         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 165                         return;
 166                 }
 167         }
 168
 169         if (parp->ar_op != htons(ARPOP_REQUEST))
 170                 return;
 171
 172         if (vid != 0) {
 173                 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
 174                                                    vid);
 175                 if (!vlandev)
 176                         return;
 177         }
 178
 179         if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
 180             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 = 1;
 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 ||
 219                             br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
 220                                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
 221                 }
 222
 223                 neigh_release(n);
 224         }
 225 }
 226 #endif
 227
 228 #if IS_ENABLED(CONFIG_IPV6)
 229 struct nd_msg *br_is_nd_neigh_msg(struct sk_buff *skb, struct nd_msg *msg)
 230 {
 231         struct nd_msg *m;
 232
 233         m = skb_header_pointer(skb, skb_network_offset(skb) +
 234                                sizeof(struct ipv6hdr), sizeof(*msg), msg);
 235         if (!m)
 236                 return NULL;
 237
 238         if (m->icmph.icmp6_code != 0 ||
 239             (m->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION &&
 240              m->icmph.icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT))
 241                 return NULL;
 242
 243         return m;
 244 }
 245
 246 static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p,
 247                        struct sk_buff *request, struct neighbour *n,
 248                        __be16 vlan_proto, u16 vlan_tci, struct nd_msg *ns)
 249 {
 250         struct net_device *dev = request->dev;
 251         struct net_bridge_vlan_group *vg;
 252         struct sk_buff *reply;
 253         struct nd_msg *na;
 254         struct ipv6hdr *pip6;
 255         int na_olen = 8; /* opt hdr + ETH_ALEN for target */
 256         int ns_olen;
 257         int i, len;
 258         u8 *daddr;
 259         u16 pvid;
 260
 261         if (!dev)
 262                 return;
 263
 264         len = LL_RESERVED_SPACE(dev) + sizeof(struct ipv6hdr) +
 265                 sizeof(*na) + na_olen + dev->needed_tailroom;
 266
 267         reply = alloc_skb(len, GFP_ATOMIC);
 268         if (!reply)
 269                 return;
 270
 271         reply->protocol = htons(ETH_P_IPV6);
 272         reply->dev = dev;
 273         skb_reserve(reply, LL_RESERVED_SPACE(dev));
 274         skb_push(reply, sizeof(struct ethhdr));
 275         skb_set_mac_header(reply, 0);
 276
 277         daddr = eth_hdr(request)->h_source;
 278
 279         /* Do we need option processing ? */
 280         ns_olen = request->len - (skb_network_offset(request) +
 281                                   sizeof(struct ipv6hdr)) - sizeof(*ns);
 282         for (i = 0; i < ns_olen - 1; i += (ns->opt[i + 1] << 3)) {
 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