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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,
 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
486 

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