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Linux/net/bridge/br_arp_nd_proxy.c

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  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] == ND_OPT_SOURCE_LL_ADDR) {
280                         daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
281                         break;
282                 }
283         }
284 
285         /* Ethernet header */
286         ether_addr_copy(eth_hdr(reply)->h_dest, daddr);
287         ether_addr_copy(eth_hdr(reply)->h_source, n->ha);
288         eth_hdr(reply)->h_proto = htons(ETH_P_IPV6);
289         reply->protocol = htons(ETH_P_IPV6);
290 
291         skb_pull(reply, sizeof(struct ethhdr));
292         skb_set_network_header(reply, 0);
293         skb_put(reply, sizeof(struct ipv6hdr));
294 
295         /* IPv6 header */
296         pip6 = ipv6_hdr(reply);
297         memset(pip6, 0, sizeof(struct ipv6hdr));
298         pip6->version = 6;
299         pip6->priority = ipv6_hdr(request)->priority;
300         pip6->nexthdr = IPPROTO_ICMPV6;
301         pip6->hop_limit = 255;
302         pip6->daddr = ipv6_hdr(request)->saddr;
303         pip6->saddr = *(struct in6_addr *)n->primary_key;
304 
305         skb_pull(reply, sizeof(struct ipv6hdr));
306         skb_set_transport_header(reply, 0);
307 
308         na = (struct nd_msg *)skb_put(reply, sizeof(*na) + na_olen);
309 
310         /* Neighbor Advertisement */
311         memset(na, 0, sizeof(*na) + na_olen);
312         na->icmph.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
313         na->icmph.icmp6_router = (n->flags & NTF_ROUTER) ? 1 : 0;
314         na->icmph.icmp6_override = 1;
315         na->icmph.icmp6_solicited = 1;
316         na->target = ns->target;
317         ether_addr_copy(&na->opt[2], n->ha);
318         na->opt[0] = ND_OPT_TARGET_LL_ADDR;
319         na->opt[1] = na_olen >> 3;
320 
321         na->icmph.icmp6_cksum = csum_ipv6_magic(&pip6->saddr,
322                                                 &pip6->daddr,
323                                                 sizeof(*na) + na_olen,
324                                                 IPPROTO_ICMPV6,
325                                                 csum_partial(na, sizeof(*na) + na_olen, 0));
326 
327         pip6->payload_len = htons(sizeof(*na) + na_olen);
328 
329         skb_push(reply, sizeof(struct ipv6hdr));
330         skb_push(reply, sizeof(struct ethhdr));
331 
332         reply->ip_summed = CHECKSUM_UNNECESSARY;
333 
334         if (p)
335                 vg = nbp_vlan_group_rcu(p);
336         else
337                 vg = br_vlan_group_rcu(br);
338         pvid = br_get_pvid(vg);
339         if (pvid == (vlan_tci & VLAN_VID_MASK))
340                 vlan_tci = 0;
341 
342         if (vlan_tci)
343                 __vlan_hwaccel_put_tag(reply, vlan_proto, vlan_tci);
344 
345         netdev_dbg(dev, "nd send dev %s dst %pI6 dst_hw %pM src %pI6 src_hw %pM\n",
346                    dev->name, &pip6->daddr, daddr, &pip6->saddr, n->ha);
347 
348         if (p) {
349                 dev_queue_xmit(reply);
350         } else {
351                 skb_reset_mac_header(reply);
352                 __skb_pull(reply, skb_network_offset(reply));
353                 reply->ip_summed = CHECKSUM_UNNECESSARY;
354                 reply->pkt_type = PACKET_HOST;
355 
356                 netif_rx_ni(reply);
357         }
358 }
359 
360 static int br_chk_addr_ip6(struct net_device *dev, void *data)
361 {
362         struct in6_addr *addr = (struct in6_addr *)data;
363 
364         if (ipv6_chk_addr(dev_net(dev), addr, dev, 0))
365                 return 1;
366 
367         return 0;
368 }
369 
370 static bool br_is_local_ip6(struct net_device *dev, struct in6_addr *addr)
371 
372 {
373         if (br_chk_addr_ip6(dev, addr))
374                 return true;
375 
376         /* check if ip is configured on upper dev */
377         if (netdev_walk_all_upper_dev_rcu(dev, br_chk_addr_ip6, addr))
378                 return true;
379 
380         return false;
381 }
382 
383 void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
384                        u16 vid, struct net_bridge_port *p, struct nd_msg *msg)
385 {
386         struct net_device *dev = br->dev;
387         struct net_device *vlandev = NULL;
388         struct in6_addr *saddr, *daddr;
389         struct ipv6hdr *iphdr;
390         struct neighbour *n;
391 
392         BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
393 
394         if (p && (p->flags & BR_NEIGH_SUPPRESS))
395                 return;
396 
397         if (msg->icmph.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT &&
398             !msg->icmph.icmp6_solicited) {
399                 /* prevent flooding to neigh suppress ports */
400                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
401                 return;
402         }
403 
404         if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
405                 return;
406 
407         iphdr = ipv6_hdr(skb);
408         saddr = &iphdr->saddr;
409         daddr = &iphdr->daddr;
410 
411         if (ipv6_addr_any(saddr) || !ipv6_addr_cmp(saddr, daddr)) {
412                 /* prevent flooding to neigh suppress ports */
413                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
414                 return;
415         }
416 
417         if (vid != 0) {
418                 /* build neigh table lookup on the vlan device */
419                 vlandev = __vlan_find_dev_deep_rcu(br->dev, skb->vlan_proto,
420                                                    vid);
421                 if (!vlandev)
422                         return;
423         } else {
424                 vlandev = dev;
425         }
426 
427         if (br_is_local_ip6(vlandev, &msg->target)) {
428                 /* its our own ip, so don't proxy reply
429                  * and don't forward to arp suppress ports
430                  */
431                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
432                 return;
433         }
434 
435         n = neigh_lookup(ipv6_stub->nd_tbl, &msg->target, vlandev);
436         if (n) {
437                 struct net_bridge_fdb_entry *f;
438 
439                 if (!(n->nud_state & NUD_VALID)) {
440                         neigh_release(n);
441                         return;
442                 }
443 
444                 f = br_fdb_find_rcu(br, n->ha, vid);
445                 if (f) {
446                         bool replied = false;
447 
448                         if (f->dst && (f->dst->flags & BR_NEIGH_SUPPRESS)) {
449                                 if (vid != 0)
450                                         br_nd_send(br, p, skb, n,
451                                                    skb->vlan_proto,
452                                                    skb_vlan_tag_get(skb), msg);
453                                 else
454                                         br_nd_send(br, p, skb, n, 0, 0, msg);
455                                 replied = true;
456                         }
457 
458                         /* If we have replied or as long as we know the
459                          * mac, indicate to NEIGH_SUPPRESS ports that we
460                          * have replied
461                          */
462                         if (replied ||
463                             br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
464                                 BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
465                 }
466                 neigh_release(n);
467         }
468 }
469 #endif
470 

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