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Linux/net/ipv4/ip_vti.c

  1 /*
  2  *      Linux NET3: IP/IP protocol decoder modified to support
  3  *                  virtual tunnel interface
  4  *
  5  *      Authors:
  6  *              Saurabh Mohan (saurabh.mohan@vyatta.com) 05/07/2012
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  *
 13  */
 14 
 15 /*
 16    This version of net/ipv4/ip_vti.c is cloned of net/ipv4/ipip.c
 17 
 18    For comments look at net/ipv4/ip_gre.c --ANK
 19  */
 20 
 21 
 22 #include <linux/capability.h>
 23 #include <linux/module.h>
 24 #include <linux/types.h>
 25 #include <linux/kernel.h>
 26 #include <linux/uaccess.h>
 27 #include <linux/skbuff.h>
 28 #include <linux/netdevice.h>
 29 #include <linux/in.h>
 30 #include <linux/tcp.h>
 31 #include <linux/udp.h>
 32 #include <linux/if_arp.h>
 33 #include <linux/init.h>
 34 #include <linux/netfilter_ipv4.h>
 35 #include <linux/if_ether.h>
 36 #include <linux/icmpv6.h>
 37 
 38 #include <net/sock.h>
 39 #include <net/ip.h>
 40 #include <net/icmp.h>
 41 #include <net/ip_tunnels.h>
 42 #include <net/inet_ecn.h>
 43 #include <net/xfrm.h>
 44 #include <net/net_namespace.h>
 45 #include <net/netns/generic.h>
 46 
 47 static struct rtnl_link_ops vti_link_ops __read_mostly;
 48 
 49 static int vti_net_id __read_mostly;
 50 static int vti_tunnel_init(struct net_device *dev);
 51 
 52 static int vti_input(struct sk_buff *skb, int nexthdr, __be32 spi,
 53                      int encap_type)
 54 {
 55         struct ip_tunnel *tunnel;
 56         const struct iphdr *iph = ip_hdr(skb);
 57         struct net *net = dev_net(skb->dev);
 58         struct ip_tunnel_net *itn = net_generic(net, vti_net_id);
 59 
 60         tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY,
 61                                   iph->saddr, iph->daddr, 0);
 62         if (tunnel) {
 63                 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 64                         goto drop;
 65 
 66                 XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = tunnel;
 67 
 68                 return xfrm_input(skb, nexthdr, spi, encap_type);
 69         }
 70 
 71         return -EINVAL;
 72 drop:
 73         kfree_skb(skb);
 74         return 0;
 75 }
 76 
 77 static int vti_rcv(struct sk_buff *skb)
 78 {
 79         XFRM_SPI_SKB_CB(skb)->family = AF_INET;
 80         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
 81 
 82         return vti_input(skb, ip_hdr(skb)->protocol, 0, 0);
 83 }
 84 
 85 static int vti_rcv_cb(struct sk_buff *skb, int err)
 86 {
 87         unsigned short family;
 88         struct net_device *dev;
 89         struct pcpu_sw_netstats *tstats;
 90         struct xfrm_state *x;
 91         struct ip_tunnel *tunnel = XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4;
 92         u32 orig_mark = skb->mark;
 93         int ret;
 94 
 95         if (!tunnel)
 96                 return 1;
 97 
 98         dev = tunnel->dev;
 99 
100         if (err) {
101                 dev->stats.rx_errors++;
102                 dev->stats.rx_dropped++;
103 
104                 return 0;
105         }
106 
107         x = xfrm_input_state(skb);
108         family = x->inner_mode->afinfo->family;
109 
110         skb->mark = be32_to_cpu(tunnel->parms.i_key);
111         ret = xfrm_policy_check(NULL, XFRM_POLICY_IN, skb, family);
112         skb->mark = orig_mark;
113 
114         if (!ret)
115                 return -EPERM;
116 
117         skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(skb->dev)));
118         skb->dev = dev;
119 
120         tstats = this_cpu_ptr(dev->tstats);
121 
122         u64_stats_update_begin(&tstats->syncp);
123         tstats->rx_packets++;
124         tstats->rx_bytes += skb->len;
125         u64_stats_update_end(&tstats->syncp);
126 
127         return 0;
128 }
129 
130 static bool vti_state_check(const struct xfrm_state *x, __be32 dst, __be32 src)
131 {
132         xfrm_address_t *daddr = (xfrm_address_t *)&dst;
133         xfrm_address_t *saddr = (xfrm_address_t *)&src;
134 
135         /* if there is no transform then this tunnel is not functional.
136          * Or if the xfrm is not mode tunnel.
137          */
138         if (!x || x->props.mode != XFRM_MODE_TUNNEL ||
139             x->props.family != AF_INET)
140                 return false;
141 
142         if (!dst)
143                 return xfrm_addr_equal(saddr, &x->props.saddr, AF_INET);
144 
145         if (!xfrm_state_addr_check(x, daddr, saddr, AF_INET))
146                 return false;
147 
148         return true;
149 }
150 
151 static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
152                             struct flowi *fl)
153 {
154         struct ip_tunnel *tunnel = netdev_priv(dev);
155         struct ip_tunnel_parm *parms = &tunnel->parms;
156         struct dst_entry *dst = skb_dst(skb);
157         struct net_device *tdev;        /* Device to other host */
158         int err;
159         int mtu;
160 
161         if (!dst) {
162                 dev->stats.tx_carrier_errors++;
163                 goto tx_error_icmp;
164         }
165 
166         dst_hold(dst);
167         dst = xfrm_lookup(tunnel->net, dst, fl, NULL, 0);
168         if (IS_ERR(dst)) {
169                 dev->stats.tx_carrier_errors++;
170                 goto tx_error_icmp;
171         }
172 
173         if (!vti_state_check(dst->xfrm, parms->iph.daddr, parms->iph.saddr)) {
174                 dev->stats.tx_carrier_errors++;
175                 dst_release(dst);
176                 goto tx_error_icmp;
177         }
178 
179         tdev = dst->dev;
180 
181         if (tdev == dev) {
182                 dst_release(dst);
183                 dev->stats.collisions++;
184                 goto tx_error;
185         }
186 
187         if (tunnel->err_count > 0) {
188                 if (time_before(jiffies,
189                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
190                         tunnel->err_count--;
191                         dst_link_failure(skb);
192                 } else
193                         tunnel->err_count = 0;
194         }
195 
196         mtu = dst_mtu(dst);
197         if (skb->len > mtu) {
198                 skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
199                 if (skb->protocol == htons(ETH_P_IP)) {
200                         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
201                                   htonl(mtu));
202                 } else {
203                         if (mtu < IPV6_MIN_MTU)
204                                 mtu = IPV6_MIN_MTU;
205 
206                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
207                 }
208 
209                 dst_release(dst);
210                 goto tx_error;
211         }
212 
213         skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(dev)));
214         skb_dst_set(skb, dst);
215         skb->dev = skb_dst(skb)->dev;
216 
217         err = dst_output(tunnel->net, skb->sk, skb);
218         if (net_xmit_eval(err) == 0)
219                 err = skb->len;
220         iptunnel_xmit_stats(dev, err);
221         return NETDEV_TX_OK;
222 
223 tx_error_icmp:
224         dst_link_failure(skb);
225 tx_error:
226         dev->stats.tx_errors++;
227         kfree_skb(skb);
228         return NETDEV_TX_OK;
229 }
230 
231 /* This function assumes it is being called from dev_queue_xmit()
232  * and that skb is filled properly by that function.
233  */
234 static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
235 {
236         struct ip_tunnel *tunnel = netdev_priv(dev);
237         struct flowi fl;
238 
239         memset(&fl, 0, sizeof(fl));
240 
241         switch (skb->protocol) {
242         case htons(ETH_P_IP):
243                 xfrm_decode_session(skb, &fl, AF_INET);
244                 memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
245                 break;
246         case htons(ETH_P_IPV6):
247                 xfrm_decode_session(skb, &fl, AF_INET6);
248                 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
249                 break;
250         default:
251                 dev->stats.tx_errors++;
252                 dev_kfree_skb(skb);
253                 return NETDEV_TX_OK;
254         }
255 
256         /* override mark with tunnel output key */
257         fl.flowi_mark = be32_to_cpu(tunnel->parms.o_key);
258 
259         return vti_xmit(skb, dev, &fl);
260 }
261 
262 static int vti4_err(struct sk_buff *skb, u32 info)
263 {
264         __be32 spi;
265         __u32 mark;
266         struct xfrm_state *x;
267         struct ip_tunnel *tunnel;
268         struct ip_esp_hdr *esph;
269         struct ip_auth_hdr *ah ;
270         struct ip_comp_hdr *ipch;
271         struct net *net = dev_net(skb->dev);
272         const struct iphdr *iph = (const struct iphdr *)skb->data;
273         int protocol = iph->protocol;
274         struct ip_tunnel_net *itn = net_generic(net, vti_net_id);
275 
276         tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY,
277                                   iph->daddr, iph->saddr, 0);
278         if (!tunnel)
279                 return -1;
280 
281         mark = be32_to_cpu(tunnel->parms.o_key);
282 
283         switch (protocol) {
284         case IPPROTO_ESP:
285                 esph = (struct ip_esp_hdr *)(skb->data+(iph->ihl<<2));
286                 spi = esph->spi;
287                 break;
288         case IPPROTO_AH:
289                 ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
290                 spi = ah->spi;
291                 break;
292         case IPPROTO_COMP:
293                 ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
294                 spi = htonl(ntohs(ipch->cpi));
295                 break;
296         default:
297                 return 0;
298         }
299 
300         switch (icmp_hdr(skb)->type) {
301         case ICMP_DEST_UNREACH:
302                 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
303                         return 0;
304         case ICMP_REDIRECT:
305                 break;
306         default:
307                 return 0;
308         }
309 
310         x = xfrm_state_lookup(net, mark, (const xfrm_address_t *)&iph->daddr,
311                               spi, protocol, AF_INET);
312         if (!x)
313                 return 0;
314 
315         if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
316                 ipv4_update_pmtu(skb, net, info, 0, 0, protocol, 0);
317         else
318                 ipv4_redirect(skb, net, 0, 0, protocol, 0);
319         xfrm_state_put(x);
320 
321         return 0;
322 }
323 
324 static int
325 vti_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
326 {
327         int err = 0;
328         struct ip_tunnel_parm p;
329 
330         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
331                 return -EFAULT;
332 
333         if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
334                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP ||
335                     p.iph.ihl != 5)
336                         return -EINVAL;
337         }
338 
339         if (!(p.i_flags & GRE_KEY))
340                 p.i_key = 0;
341         if (!(p.o_flags & GRE_KEY))
342                 p.o_key = 0;
343 
344         p.i_flags = VTI_ISVTI;
345 
346         err = ip_tunnel_ioctl(dev, &p, cmd);
347         if (err)
348                 return err;
349 
350         if (cmd != SIOCDELTUNNEL) {
351                 p.i_flags |= GRE_KEY;
352                 p.o_flags |= GRE_KEY;
353         }
354 
355         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
356                 return -EFAULT;
357         return 0;
358 }
359 
360 static const struct net_device_ops vti_netdev_ops = {
361         .ndo_init       = vti_tunnel_init,
362         .ndo_uninit     = ip_tunnel_uninit,
363         .ndo_start_xmit = vti_tunnel_xmit,
364         .ndo_do_ioctl   = vti_tunnel_ioctl,
365         .ndo_change_mtu = ip_tunnel_change_mtu,
366         .ndo_get_stats64 = ip_tunnel_get_stats64,
367         .ndo_get_iflink = ip_tunnel_get_iflink,
368 };
369 
370 static void vti_tunnel_setup(struct net_device *dev)
371 {
372         dev->netdev_ops         = &vti_netdev_ops;
373         dev->type               = ARPHRD_TUNNEL;
374         ip_tunnel_setup(dev, vti_net_id);
375 }
376 
377 static int vti_tunnel_init(struct net_device *dev)
378 {
379         struct ip_tunnel *tunnel = netdev_priv(dev);
380         struct iphdr *iph = &tunnel->parms.iph;
381 
382         memcpy(dev->dev_addr, &iph->saddr, 4);
383         memcpy(dev->broadcast, &iph->daddr, 4);
384 
385         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
386         dev->mtu                = ETH_DATA_LEN;
387         dev->flags              = IFF_NOARP;
388         dev->addr_len           = 4;
389         dev->features           |= NETIF_F_LLTX;
390         netif_keep_dst(dev);
391 
392         return ip_tunnel_init(dev);
393 }
394 
395 static void __net_init vti_fb_tunnel_init(struct net_device *dev)
396 {
397         struct ip_tunnel *tunnel = netdev_priv(dev);
398         struct iphdr *iph = &tunnel->parms.iph;
399 
400         iph->version            = 4;
401         iph->protocol           = IPPROTO_IPIP;
402         iph->ihl                = 5;
403 }
404 
405 static struct xfrm4_protocol vti_esp4_protocol __read_mostly = {
406         .handler        =       vti_rcv,
407         .input_handler  =       vti_input,
408         .cb_handler     =       vti_rcv_cb,
409         .err_handler    =       vti4_err,
410         .priority       =       100,
411 };
412 
413 static struct xfrm4_protocol vti_ah4_protocol __read_mostly = {
414         .handler        =       vti_rcv,
415         .input_handler  =       vti_input,
416         .cb_handler     =       vti_rcv_cb,
417         .err_handler    =       vti4_err,
418         .priority       =       100,
419 };
420 
421 static struct xfrm4_protocol vti_ipcomp4_protocol __read_mostly = {
422         .handler        =       vti_rcv,
423         .input_handler  =       vti_input,
424         .cb_handler     =       vti_rcv_cb,
425         .err_handler    =       vti4_err,
426         .priority       =       100,
427 };
428 
429 static int __net_init vti_init_net(struct net *net)
430 {
431         int err;
432         struct ip_tunnel_net *itn;
433 
434         err = ip_tunnel_init_net(net, vti_net_id, &vti_link_ops, "ip_vti0");
435         if (err)
436                 return err;
437         itn = net_generic(net, vti_net_id);
438         vti_fb_tunnel_init(itn->fb_tunnel_dev);
439         return 0;
440 }
441 
442 static void __net_exit vti_exit_net(struct net *net)
443 {
444         struct ip_tunnel_net *itn = net_generic(net, vti_net_id);
445         ip_tunnel_delete_net(itn, &vti_link_ops);
446 }
447 
448 static struct pernet_operations vti_net_ops = {
449         .init = vti_init_net,
450         .exit = vti_exit_net,
451         .id   = &vti_net_id,
452         .size = sizeof(struct ip_tunnel_net),
453 };
454 
455 static int vti_tunnel_validate(struct nlattr *tb[], struct nlattr *data[])
456 {
457         return 0;
458 }
459 
460 static void vti_netlink_parms(struct nlattr *data[],
461                               struct ip_tunnel_parm *parms)
462 {
463         memset(parms, 0, sizeof(*parms));
464 
465         parms->iph.protocol = IPPROTO_IPIP;
466 
467         if (!data)
468                 return;
469 
470         parms->i_flags = VTI_ISVTI;
471 
472         if (data[IFLA_VTI_LINK])
473                 parms->link = nla_get_u32(data[IFLA_VTI_LINK]);
474 
475         if (data[IFLA_VTI_IKEY])
476                 parms->i_key = nla_get_be32(data[IFLA_VTI_IKEY]);
477 
478         if (data[IFLA_VTI_OKEY])
479                 parms->o_key = nla_get_be32(data[IFLA_VTI_OKEY]);
480 
481         if (data[IFLA_VTI_LOCAL])
482                 parms->iph.saddr = nla_get_in_addr(data[IFLA_VTI_LOCAL]);
483 
484         if (data[IFLA_VTI_REMOTE])
485                 parms->iph.daddr = nla_get_in_addr(data[IFLA_VTI_REMOTE]);
486 
487 }
488 
489 static int vti_newlink(struct net *src_net, struct net_device *dev,
490                        struct nlattr *tb[], struct nlattr *data[])
491 {
492         struct ip_tunnel_parm parms;
493 
494         vti_netlink_parms(data, &parms);
495         return ip_tunnel_newlink(dev, tb, &parms);
496 }
497 
498 static int vti_changelink(struct net_device *dev, struct nlattr *tb[],
499                           struct nlattr *data[])
500 {
501         struct ip_tunnel_parm p;
502 
503         vti_netlink_parms(data, &p);
504         return ip_tunnel_changelink(dev, tb, &p);
505 }
506 
507 static size_t vti_get_size(const struct net_device *dev)
508 {
509         return
510                 /* IFLA_VTI_LINK */
511                 nla_total_size(4) +
512                 /* IFLA_VTI_IKEY */
513                 nla_total_size(4) +
514                 /* IFLA_VTI_OKEY */
515                 nla_total_size(4) +
516                 /* IFLA_VTI_LOCAL */
517                 nla_total_size(4) +
518                 /* IFLA_VTI_REMOTE */
519                 nla_total_size(4) +
520                 0;
521 }
522 
523 static int vti_fill_info(struct sk_buff *skb, const struct net_device *dev)
524 {
525         struct ip_tunnel *t = netdev_priv(dev);
526         struct ip_tunnel_parm *p = &t->parms;
527 
528         nla_put_u32(skb, IFLA_VTI_LINK, p->link);
529         nla_put_be32(skb, IFLA_VTI_IKEY, p->i_key);
530         nla_put_be32(skb, IFLA_VTI_OKEY, p->o_key);
531         nla_put_in_addr(skb, IFLA_VTI_LOCAL, p->iph.saddr);
532         nla_put_in_addr(skb, IFLA_VTI_REMOTE, p->iph.daddr);
533 
534         return 0;
535 }
536 
537 static const struct nla_policy vti_policy[IFLA_VTI_MAX + 1] = {
538         [IFLA_VTI_LINK]         = { .type = NLA_U32 },
539         [IFLA_VTI_IKEY]         = { .type = NLA_U32 },
540         [IFLA_VTI_OKEY]         = { .type = NLA_U32 },
541         [IFLA_VTI_LOCAL]        = { .len = FIELD_SIZEOF(struct iphdr, saddr) },
542         [IFLA_VTI_REMOTE]       = { .len = FIELD_SIZEOF(struct iphdr, daddr) },
543 };
544 
545 static struct rtnl_link_ops vti_link_ops __read_mostly = {
546         .kind           = "vti",
547         .maxtype        = IFLA_VTI_MAX,
548         .policy         = vti_policy,
549         .priv_size      = sizeof(struct ip_tunnel),
550         .setup          = vti_tunnel_setup,
551         .validate       = vti_tunnel_validate,
552         .newlink        = vti_newlink,
553         .changelink     = vti_changelink,
554         .dellink        = ip_tunnel_dellink,
555         .get_size       = vti_get_size,
556         .fill_info      = vti_fill_info,
557         .get_link_net   = ip_tunnel_get_link_net,
558 };
559 
560 static int __init vti_init(void)
561 {
562         const char *msg;
563         int err;
564 
565         pr_info("IPv4 over IPsec tunneling driver\n");
566 
567         msg = "tunnel device";
568         err = register_pernet_device(&vti_net_ops);
569         if (err < 0)
570                 goto pernet_dev_failed;
571 
572         msg = "tunnel protocols";
573         err = xfrm4_protocol_register(&vti_esp4_protocol, IPPROTO_ESP);
574         if (err < 0)
575                 goto xfrm_proto_esp_failed;
576         err = xfrm4_protocol_register(&vti_ah4_protocol, IPPROTO_AH);
577         if (err < 0)
578                 goto xfrm_proto_ah_failed;
579         err = xfrm4_protocol_register(&vti_ipcomp4_protocol, IPPROTO_COMP);
580         if (err < 0)
581                 goto xfrm_proto_comp_failed;
582 
583         msg = "netlink interface";
584         err = rtnl_link_register(&vti_link_ops);
585         if (err < 0)
586                 goto rtnl_link_failed;
587 
588         return err;
589 
590 rtnl_link_failed:
591         xfrm4_protocol_deregister(&vti_ipcomp4_protocol, IPPROTO_COMP);
592 xfrm_proto_comp_failed:
593         xfrm4_protocol_deregister(&vti_ah4_protocol, IPPROTO_AH);
594 xfrm_proto_ah_failed:
595         xfrm4_protocol_deregister(&vti_esp4_protocol, IPPROTO_ESP);
596 xfrm_proto_esp_failed:
597         unregister_pernet_device(&vti_net_ops);
598 pernet_dev_failed:
599         pr_err("vti init: failed to register %s\n", msg);
600         return err;
601 }
602 
603 static void __exit vti_fini(void)
604 {
605         rtnl_link_unregister(&vti_link_ops);
606         xfrm4_protocol_deregister(&vti_ipcomp4_protocol, IPPROTO_COMP);
607         xfrm4_protocol_deregister(&vti_ah4_protocol, IPPROTO_AH);
608         xfrm4_protocol_deregister(&vti_esp4_protocol, IPPROTO_ESP);
609         unregister_pernet_device(&vti_net_ops);
610 }
611 
612 module_init(vti_init);
613 module_exit(vti_fini);
614 MODULE_LICENSE("GPL");
615 MODULE_ALIAS_RTNL_LINK("vti");
616 MODULE_ALIAS_NETDEV("ip_vti0");
617 

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