net/bridge/br_arp_nd_proxy.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  Handle bridge arp/nd proxy/suppress
0004  *
0005  *  Copyright (C) 2017 Cumulus Networks
0006  *  Copyright (c) 2017 Roopa Prabhu <roopa@cumulusnetworks.com>
0007  *
0008  *  Authors:
0009  *  Roopa Prabhu <roopa@cumulusnetworks.com>
0010  */
0011
0012 #include <linux/kernel.h>
0013 #include <linux/netdevice.h>
0014 #include <linux/etherdevice.h>
0015 #include <linux/neighbour.h>
0016 #include <net/arp.h>
0017 #include <linux/if_vlan.h>
0018 #include <linux/inetdevice.h>
0019 #include <net/addrconf.h>
0020 #include <net/ipv6_stubs.h>
0021 #if IS_ENABLED(CONFIG_IPV6)
0022 #include <net/ip6_checksum.h>
0023 #endif
0024
0025 #include "br_private.h"
0026
0027 void br_recalculate_neigh_suppress_enabled(struct net_bridge *br)
0028 {
0029     struct net_bridge_port *p;
0030     bool neigh_suppress = false;
0031
0032     list_for_each_entry(p, &br->port_list, list) {
0033         if (p->flags & BR_NEIGH_SUPPRESS) {
0034             neigh_suppress = true;
0035             break;
0036         }
0037     }
0038
0039     br_opt_toggle(br, BROPT_NEIGH_SUPPRESS_ENABLED, neigh_suppress);
0040 }
0041
0042 #if IS_ENABLED(CONFIG_INET)
0043 static void br_arp_send(struct net_bridge *br, struct net_bridge_port *p,
0044             struct net_device *dev, __be32 dest_ip, __be32 src_ip,
0045             const unsigned char *dest_hw,
0046             const unsigned char *src_hw,
0047             const unsigned char *target_hw,
0048             __be16 vlan_proto, u16 vlan_tci)
0049 {
0050     struct net_bridge_vlan_group *vg;
0051     struct sk_buff *skb;
0052     u16 pvid;
0053
0054     netdev_dbg(dev, "arp send dev %s dst %pI4 dst_hw %pM src %pI4 src_hw %pM\n",
0055            dev->name, &dest_ip, dest_hw, &src_ip, src_hw);
0056
0057     if (!vlan_tci) {
0058         arp_send(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
0059              dest_hw, src_hw, target_hw);
0060         return;
0061     }
0062
0063     skb = arp_create(ARPOP_REPLY, ETH_P_ARP, dest_ip, dev, src_ip,
0064              dest_hw, src_hw, target_hw);
0065     if (!skb)
0066         return;
0067
0068     if (p)
0069         vg = nbp_vlan_group_rcu(p);
0070     else
0071         vg = br_vlan_group_rcu(br);
0072     pvid = br_get_pvid(vg);
0073     if (pvid == (vlan_tci & VLAN_VID_MASK))
0074         vlan_tci = 0;
0075
0076     if (vlan_tci)
0077         __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
0078
0079     if (p) {
0080         arp_xmit(skb);
0081     } else {
0082         skb_reset_mac_header(skb);
0083         __skb_pull(skb, skb_network_offset(skb));
0084         skb->ip_summed = CHECKSUM_UNNECESSARY;
0085         skb->pkt_type = PACKET_HOST;
0086
0087         netif_rx(skb);
0088     }
0089 }
0090
0091 static int br_chk_addr_ip(struct net_device *dev,
0092               struct netdev_nested_priv *priv)
0093 {
0094     __be32 ip = *(__be32 *)priv->data;
0095     struct in_device *in_dev;
0096     __be32 addr = 0;
0097
0098     in_dev = __in_dev_get_rcu(dev);
0099     if (in_dev)
0100         addr = inet_confirm_addr(dev_net(dev), in_dev, 0, ip,
0101                      RT_SCOPE_HOST);
0102
0103     if (addr == ip)
0104         return 1;
0105
0106     return 0;
0107 }
0108
0109 static bool br_is_local_ip(struct net_device *dev, __be32 ip)
0110 {
0111     struct netdev_nested_priv priv = {
0112         .data = (void *)&ip,
0113     };
0114
0115     if (br_chk_addr_ip(dev, &priv))
0116         return true;
0117
0118     /* check if ip is configured on upper dev */
0119     if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip, &priv))
0120         return true;
0121
0122     return false;
0123 }
0124
0125 void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
0126                   u16 vid, struct net_bridge_port *p)
0127 {
0128     struct net_device *dev = br->dev;
0129     struct net_device *vlandev = dev;
0130     struct neighbour *n;
0131     struct arphdr *parp;
0132     u8 *arpptr, *sha;
0133     __be32 sip, tip;
0134
0135     BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
0136
0137     if ((dev->flags & IFF_NOARP) ||
0138         !pskb_may_pull(skb, arp_hdr_len(dev)))
0139         return;
0140
0141     parp = arp_hdr(skb);
0142
0143     if (parp->ar_pro != htons(ETH_P_IP) ||
0144         parp->ar_hln != dev->addr_len ||
0145         parp->ar_pln != 4)
0146         return;
0147
0148     arpptr = (u8 *)parp + sizeof(struct arphdr);
0149     sha = arpptr;
0150     arpptr += dev->addr_len;    /* sha */
0151     memcpy(&sip, arpptr, sizeof(sip));
0152     arpptr += sizeof(sip);
0153     arpptr += dev->addr_len;    /* tha */
0154     memcpy(&tip, arpptr, sizeof(tip));
0155
0156     if (ipv4_is_loopback(tip) ||
0157         ipv4_is_multicast(tip))
0158         return;
0159
0160     if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED)) {
0161         if (p && (p->flags & BR_NEIGH_SUPPRESS))
0162             return;
0163         if (parp->ar_op != htons(ARPOP_RREQUEST) &&
0164             parp->ar_op != htons(ARPOP_RREPLY) &&
0165             (ipv4_is_zeronet(sip) || sip == tip)) {
0166             /* prevent flooding to neigh suppress ports */
0167             BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
0168             return;
0169         }
0170     }
0171
0172     if (parp->ar_op != htons(ARPOP_REQUEST))
0173         return;
0174
0175     if (vid != 0) {
0176         vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
0177                            vid);
0178         if (!vlandev)
0179             return;
0180     }
0181
0182     if (br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
0183         br_is_local_ip(vlandev, tip)) {
0184         /* its our local ip, so don't proxy reply
0185          * and don't forward to neigh suppress ports
0186          */
0187         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
0188         return;
0189     }
0190
0191     n = neigh_lookup(&arp_tbl, &tip, vlandev);
0192     if (n) {
0193         struct net_bridge_fdb_entry *f;
0194
0195         if (!(n->nud_state & NUD_VALID)) {
0196             neigh_release(n);
0197             return;
0198         }
0199
0200         f = br_fdb_find_rcu(br, n->ha, vid);
0201         if (f) {
0202             bool replied = false;
0203
0204             if ((p && (p->flags & BR_PROXYARP)) ||
0205                 (f->dst && (f->dst->flags & (BR_PROXYARP_WIFI |
0206                              BR_NEIGH_SUPPRESS)))) {
0207                 if (!vid)
0208                     br_arp_send(br, p, skb->dev, sip, tip,
0209                             sha, n->ha, sha, 0, 0);
0210                 else
0211                     br_arp_send(br, p, skb->dev, sip, tip,
0212                             sha, n->ha, sha,
0213                             skb->vlan_proto,
0214                             skb_vlan_tag_get(skb));
0215                 replied = true;
0216             }
0217
0218             /* If we have replied or as long as we know the
0219              * mac, indicate to arp replied
0220              */
0221             if (replied ||
0222                 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
0223                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
0224         }
0225
0226         neigh_release(n);
0227     }
0228 }
0229 #endif
0230
0231 #if IS_ENABLED(CONFIG_IPV6)
0232 struct nd_msg *br_is_nd_neigh_msg(struct sk_buff *skb, struct nd_msg *msg)
0233 {
0234     struct nd_msg *m;
0235
0236     m = skb_header_pointer(skb, skb_network_offset(skb) +
0237                    sizeof(struct ipv6hdr), sizeof(*msg), msg);
0238     if (!m)
0239         return NULL;
0240
0241     if (m->icmph.icmp6_code != 0 ||
0242         (m->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION &&
0243          m->icmph.icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT))
0244         return NULL;
0245
0246     return m;
0247 }
0248
0249 static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p,
0250                struct sk_buff *request, struct neighbour *n,
0251                __be16 vlan_proto, u16 vlan_tci, struct nd_msg *ns)
0252 {
0253     struct net_device *dev = request->dev;
0254     struct net_bridge_vlan_group *vg;
0255     struct sk_buff *reply;
0256     struct nd_msg *na;
0257     struct ipv6hdr *pip6;
0258     int na_olen = 8; /* opt hdr + ETH_ALEN for target */
0259     int ns_olen;
0260     int i, len;
0261     u8 *daddr;
0262     u16 pvid;
0263
0264     if (!dev)
0265         return;
0266
0267     len = LL_RESERVED_SPACE(dev) + sizeof(struct ipv6hdr) +
0268         sizeof(*na) + na_olen + dev->needed_tailroom;
0269
0270     reply = alloc_skb(len, GFP_ATOMIC);
0271     if (!reply)
0272         return;
0273
0274     reply->protocol = htons(ETH_P_IPV6);
0275     reply->dev = dev;
0276     skb_reserve(reply, LL_RESERVED_SPACE(dev));
0277     skb_push(reply, sizeof(struct ethhdr));
0278     skb_set_mac_header(reply, 0);
0279
0280     daddr = eth_hdr(request)->h_source;
0281
0282     /* Do we need option processing ? */
0283     ns_olen = request->len - (skb_network_offset(request) +
0284                   sizeof(struct ipv6hdr)) - sizeof(*ns);
0285     for (i = 0; i < ns_olen - 1; i += (ns->opt[i + 1] << 3)) {
0286         if (!ns->opt[i + 1]) {
0287             kfree_skb(reply);
0288             return;
0289         }
0290         if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) {
0291             daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
0292             break;
0293         }
0294     }
0295
0296     /* Ethernet header */
0297     ether_addr_copy(eth_hdr(reply)->h_dest, daddr);
0298     ether_addr_copy(eth_hdr(reply)->h_source, n->ha);
0299     eth_hdr(reply)->h_proto = htons(ETH_P_IPV6);
0300     reply->protocol = htons(ETH_P_IPV6);
0301
0302     skb_pull(reply, sizeof(struct ethhdr));
0303     skb_set_network_header(reply, 0);
0304     skb_put(reply, sizeof(struct ipv6hdr));
0305
0306     /* IPv6 header */
0307     pip6 = ipv6_hdr(reply);
0308     memset(pip6, 0, sizeof(struct ipv6hdr));
0309     pip6->version = 6;
0310     pip6->priority = ipv6_hdr(request)->priority;
0311     pip6->nexthdr = IPPROTO_ICMPV6;
0312     pip6->hop_limit = 255;
0313     pip6->daddr = ipv6_hdr(request)->saddr;
0314     pip6->saddr = *(struct in6_addr *)n->primary_key;
0315
0316     skb_pull(reply, sizeof(struct ipv6hdr));
0317     skb_set_transport_header(reply, 0);
0318
0319     na = (struct nd_msg *)skb_put(reply, sizeof(*na) + na_olen);
0320
0321     /* Neighbor Advertisement */
0322     memset(na, 0, sizeof(*na) + na_olen);
0323     na->icmph.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
0324     na->icmph.icmp6_router = (n->flags & NTF_ROUTER) ? 1 : 0;
0325     na->icmph.icmp6_override = 1;
0326     na->icmph.icmp6_solicited = 1;
0327     na->target = ns->target;
0328     ether_addr_copy(&na->opt[2], n->ha);
0329     na->opt[0] = ND_OPT_TARGET_LL_ADDR;
0330     na->opt[1] = na_olen >> 3;
0331
0332     na->icmph.icmp6_cksum = csum_ipv6_magic(&pip6->saddr,
0333                         &pip6->daddr,
0334                         sizeof(*na) + na_olen,
0335                         IPPROTO_ICMPV6,
0336                         csum_partial(na, sizeof(*na) + na_olen, 0));
0337
0338     pip6->payload_len = htons(sizeof(*na) + na_olen);
0339
0340     skb_push(reply, sizeof(struct ipv6hdr));
0341     skb_push(reply, sizeof(struct ethhdr));
0342
0343     reply->ip_summed = CHECKSUM_UNNECESSARY;
0344
0345     if (p)
0346         vg = nbp_vlan_group_rcu(p);
0347     else
0348         vg = br_vlan_group_rcu(br);
0349     pvid = br_get_pvid(vg);
0350     if (pvid == (vlan_tci & VLAN_VID_MASK))
0351         vlan_tci = 0;
0352
0353     if (vlan_tci)
0354         __vlan_hwaccel_put_tag(reply, vlan_proto, vlan_tci);
0355
0356     netdev_dbg(dev, "nd send dev %s dst %pI6 dst_hw %pM src %pI6 src_hw %pM\n",
0357            dev->name, &pip6->daddr, daddr, &pip6->saddr, n->ha);
0358
0359     if (p) {
0360         dev_queue_xmit(reply);
0361     } else {
0362         skb_reset_mac_header(reply);
0363         __skb_pull(reply, skb_network_offset(reply));
0364         reply->ip_summed = CHECKSUM_UNNECESSARY;
0365         reply->pkt_type = PACKET_HOST;
0366
0367         netif_rx(reply);
0368     }
0369 }
0370
0371 static int br_chk_addr_ip6(struct net_device *dev,
0372                struct netdev_nested_priv *priv)
0373 {
0374     struct in6_addr *addr = (struct in6_addr *)priv->data;
0375
0376     if (ipv6_chk_addr(dev_net(dev), addr, dev, 0))
0377         return 1;
0378
0379     return 0;
0380 }
0381
0382 static bool br_is_local_ip6(struct net_device *dev, struct in6_addr *addr)
0383
0384 {
0385     struct netdev_nested_priv priv = {
0386         .data = (void *)addr,
0387     };
0388
0389     if (br_chk_addr_ip6(dev, &priv))
0390         return true;
0391
0392     /* check if ip is configured on upper dev */
0393     if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip6, &priv))
0394         return true;
0395
0396     return false;
0397 }
0398
0399 void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
0400                u16 vid, struct net_bridge_port *p, struct nd_msg *msg)
0401 {
0402     struct net_device *dev = br->dev;
0403     struct net_device *vlandev = NULL;
0404     struct in6_addr *saddr, *daddr;
0405     struct ipv6hdr *iphdr;
0406     struct neighbour *n;
0407
0408     BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
0409
0410     if (p && (p->flags & BR_NEIGH_SUPPRESS))
0411         return;
0412
0413     if (msg->icmph.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT &&
0414         !msg->icmph.icmp6_solicited) {
0415         /* prevent flooding to neigh suppress ports */
0416         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
0417         return;
0418     }
0419
0420     if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
0421         return;
0422
0423     iphdr = ipv6_hdr(skb);
0424     saddr = &iphdr->saddr;
0425     daddr = &iphdr->daddr;
0426
0427     if (ipv6_addr_any(saddr) || !ipv6_addr_cmp(saddr, daddr)) {
0428         /* prevent flooding to neigh suppress ports */
0429         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
0430         return;
0431     }
0432
0433     if (vid != 0) {
0434         /* build neigh table lookup on the vlan device */
0435         vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
0436                            vid);
0437         if (!vlandev)
0438             return;
0439     } else {
0440         vlandev = dev;
0441     }
0442
0443     if (br_is_local_ip6(vlandev, &msg->target)) {
0444         /* its our own ip, so don't proxy reply
0445          * and don't forward to arp suppress ports
0446          */
0447         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
0448         return;
0449     }
0450
0451     n = neigh_lookup(ipv6_stub->nd_tbl, &msg->target, vlandev);
0452     if (n) {
0453         struct net_bridge_fdb_entry *f;
0454
0455         if (!(n->nud_state & NUD_VALID)) {
0456             neigh_release(n);
0457             return;
0458         }
0459
0460         f = br_fdb_find_rcu(br, n->ha, vid);
0461         if (f) {
0462             bool replied = false;
0463
0464             if (f->dst && (f->dst->flags & BR_NEIGH_SUPPRESS)) {
0465                 if (vid != 0)
0466                     br_nd_send(br, p, skb, n,
0467                            skb->vlan_proto,
0468                            skb_vlan_tag_get(skb), msg);
0469                 else
0470                     br_nd_send(br, p, skb, n, 0, 0, msg);
0471                 replied = true;
0472             }
0473
0474             /* If we have replied or as long as we know the
0475              * mac, indicate to NEIGH_SUPPRESS ports that we
0476              * have replied
0477              */
0478             if (replied ||
0479                 br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
0480                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
0481         }
0482         neigh_release(n);
0483     }
0484 }
0485 #endif