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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 
160         if (!dst) {
161                 dev->stats.tx_carrier_errors++;
162                 goto tx_error_icmp;
163         }
164 
165         dst_hold(dst);
166         dst = xfrm_lookup(tunnel->net, dst, fl, NULL, 0);
167         if (IS_ERR(dst)) {
168                 dev->stats.tx_carrier_errors++;
169                 goto tx_error_icmp;
170         }
171 
172         if (!vti_state_check(dst->xfrm, parms->iph.daddr, parms->iph.saddr)) {
173                 dev->stats.tx_carrier_errors++;
174                 dst_release(dst);
175                 goto tx_error_icmp;
176         }
177 
178         tdev = dst->dev;
179 
180         if (tdev == dev) {
181                 dst_release(dst);
182                 dev->stats.collisions++;
183                 goto tx_error;
184         }
185 
186         if (tunnel->err_count > 0) {
187                 if (time_before(jiffies,
188                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
189                         tunnel->err_count--;
190                         dst_link_failure(skb);
191                 } else
192                         tunnel->err_count = 0;
193         }
194 
195         skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(dev)));
196         skb_dst_set(skb, dst);
197         skb->dev = skb_dst(skb)->dev;
198 
199         err = dst_output(tunnel->net, skb->sk, skb);
200         if (net_xmit_eval(err) == 0)
201                 err = skb->len;
202         iptunnel_xmit_stats(dev, err);
203         return NETDEV_TX_OK;
204 
205 tx_error_icmp:
206         dst_link_failure(skb);
207 tx_error:
208         dev->stats.tx_errors++;
209         kfree_skb(skb);
210         return NETDEV_TX_OK;
211 }
212 
213 /* This function assumes it is being called from dev_queue_xmit()
214  * and that skb is filled properly by that function.
215  */
216 static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
217 {
218         struct ip_tunnel *tunnel = netdev_priv(dev);
219         struct flowi fl;
220 
221         memset(&fl, 0, sizeof(fl));
222 
223         switch (skb->protocol) {
224         case htons(ETH_P_IP):
225                 xfrm_decode_session(skb, &fl, AF_INET);
226                 memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
227                 break;
228         case htons(ETH_P_IPV6):
229                 xfrm_decode_session(skb, &fl, AF_INET6);
230                 memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
231                 break;
232         default:
233                 dev->stats.tx_errors++;
234                 dev_kfree_skb(skb);
235                 return NETDEV_TX_OK;
236         }
237 
238         /* override mark with tunnel output key */
239         fl.flowi_mark = be32_to_cpu(tunnel->parms.o_key);
240 
241         return vti_xmit(skb, dev, &fl);
242 }
243 
244 static int vti4_err(struct sk_buff *skb, u32 info)
245 {
246         __be32 spi;
247         __u32 mark;
248         struct xfrm_state *x;
249         struct ip_tunnel *tunnel;
250         struct ip_esp_hdr *esph;
251         struct ip_auth_hdr *ah ;
252         struct ip_comp_hdr *ipch;
253         struct net *net = dev_net(skb->dev);
254         const struct iphdr *iph = (const struct iphdr *)skb->data;
255         int protocol = iph->protocol;
256         struct ip_tunnel_net *itn = net_generic(net, vti_net_id);
257 
258         tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY,
259                                   iph->daddr, iph->saddr, 0);
260         if (!tunnel)
261                 return -1;
262 
263         mark = be32_to_cpu(tunnel->parms.o_key);
264 
265         switch (protocol) {
266         case IPPROTO_ESP:
267                 esph = (struct ip_esp_hdr *)(skb->data+(iph->ihl<<2));
268                 spi = esph->spi;
269                 break;
270         case IPPROTO_AH:
271                 ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
272                 spi = ah->spi;
273                 break;
274         case IPPROTO_COMP:
275                 ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
276                 spi = htonl(ntohs(ipch->cpi));
277                 break;
278         default:
279                 return 0;
280         }
281 
282         switch (icmp_hdr(skb)->type) {
283         case ICMP_DEST_UNREACH:
284                 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
285                         return 0;
286         case ICMP_REDIRECT:
287                 break;
288         default:
289                 return 0;
290         }
291 
292         x = xfrm_state_lookup(net, mark, (const xfrm_address_t *)&iph->daddr,
293                               spi, protocol, AF_INET);
294         if (!x)
295                 return 0;
296 
297         if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
298                 ipv4_update_pmtu(skb, net, info, 0, 0, protocol, 0);
299         else
300                 ipv4_redirect(skb, net, 0, 0, protocol, 0);
301         xfrm_state_put(x);
302 
303         return 0;
304 }
305 
306 static int
307 vti_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
308 {
309         int err = 0;
310         struct ip_tunnel_parm p;
311 
312         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
313                 return -EFAULT;
314 
315         if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
316                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP ||
317                     p.iph.ihl != 5)
318                         return -EINVAL;
319         }
320 
321         if (!(p.i_flags & GRE_KEY))
322                 p.i_key = 0;
323         if (!(p.o_flags & GRE_KEY))
324                 p.o_key = 0;
325 
326         p.i_flags = VTI_ISVTI;
327 
328         err = ip_tunnel_ioctl(dev, &p, cmd);
329         if (err)
330                 return err;
331 
332         if (cmd != SIOCDELTUNNEL) {
333                 p.i_flags |= GRE_KEY;
334                 p.o_flags |= GRE_KEY;
335         }
336 
337         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
338                 return -EFAULT;
339         return 0;
340 }
341 
342 static const struct net_device_ops vti_netdev_ops = {
343         .ndo_init       = vti_tunnel_init,
344         .ndo_uninit     = ip_tunnel_uninit,
345         .ndo_start_xmit = vti_tunnel_xmit,
346         .ndo_do_ioctl   = vti_tunnel_ioctl,
347         .ndo_change_mtu = ip_tunnel_change_mtu,
348         .ndo_get_stats64 = ip_tunnel_get_stats64,
349         .ndo_get_iflink = ip_tunnel_get_iflink,
350 };
351 
352 static void vti_tunnel_setup(struct net_device *dev)
353 {
354         dev->netdev_ops         = &vti_netdev_ops;
355         dev->type               = ARPHRD_TUNNEL;
356         ip_tunnel_setup(dev, vti_net_id);
357 }
358 
359 static int vti_tunnel_init(struct net_device *dev)
360 {
361         struct ip_tunnel *tunnel = netdev_priv(dev);
362         struct iphdr *iph = &tunnel->parms.iph;
363 
364         memcpy(dev->dev_addr, &iph->saddr, 4);
365         memcpy(dev->broadcast, &iph->daddr, 4);
366 
367         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
368         dev->mtu                = ETH_DATA_LEN;
369         dev->flags              = IFF_NOARP;
370         dev->addr_len           = 4;
371         dev->features           |= NETIF_F_LLTX;
372         netif_keep_dst(dev);
373 
374         return ip_tunnel_init(dev);
375 }
376 
377 static void __net_init vti_fb_tunnel_init(struct net_device *dev)
378 {
379         struct ip_tunnel *tunnel = netdev_priv(dev);
380         struct iphdr *iph = &tunnel->parms.iph;
381 
382         iph->version            = 4;
383         iph->protocol           = IPPROTO_IPIP;
384         iph->ihl                = 5;
385 }
386 
387 static struct xfrm4_protocol vti_esp4_protocol __read_mostly = {
388         .handler        =       vti_rcv,
389         .input_handler  =       vti_input,
390         .cb_handler     =       vti_rcv_cb,
391         .err_handler    =       vti4_err,
392         .priority       =       100,
393 };
394 
395 static struct xfrm4_protocol vti_ah4_protocol __read_mostly = {
396         .handler        =       vti_rcv,
397         .input_handler  =       vti_input,
398         .cb_handler     =       vti_rcv_cb,
399         .err_handler    =       vti4_err,
400         .priority       =       100,
401 };
402 
403 static struct xfrm4_protocol vti_ipcomp4_protocol __read_mostly = {
404         .handler        =       vti_rcv,
405         .input_handler  =       vti_input,
406         .cb_handler     =       vti_rcv_cb,
407         .err_handler    =       vti4_err,
408         .priority       =       100,
409 };
410 
411 static int __net_init vti_init_net(struct net *net)
412 {
413         int err;
414         struct ip_tunnel_net *itn;
415 
416         err = ip_tunnel_init_net(net, vti_net_id, &vti_link_ops, "ip_vti0");
417         if (err)
418                 return err;
419         itn = net_generic(net, vti_net_id);
420         vti_fb_tunnel_init(itn->fb_tunnel_dev);
421         return 0;
422 }
423 
424 static void __net_exit vti_exit_net(struct net *net)
425 {
426         struct ip_tunnel_net *itn = net_generic(net, vti_net_id);
427         ip_tunnel_delete_net(itn, &vti_link_ops);
428 }
429 
430 static struct pernet_operations vti_net_ops = {
431         .init = vti_init_net,
432         .exit = vti_exit_net,
433         .id   = &vti_net_id,
434         .size = sizeof(struct ip_tunnel_net),
435 };
436 
437 static int vti_tunnel_validate(struct nlattr *tb[], struct nlattr *data[])
438 {
439         return 0;
440 }
441 
442 static void vti_netlink_parms(struct nlattr *data[],
443                               struct ip_tunnel_parm *parms)
444 {
445         memset(parms, 0, sizeof(*parms));
446 
447         parms->iph.protocol = IPPROTO_IPIP;
448 
449         if (!data)
450                 return;
451 
452         parms->i_flags = VTI_ISVTI;
453 
454         if (data[IFLA_VTI_LINK])
455                 parms->link = nla_get_u32(data[IFLA_VTI_LINK]);
456 
457         if (data[IFLA_VTI_IKEY])
458                 parms->i_key = nla_get_be32(data[IFLA_VTI_IKEY]);
459 
460         if (data[IFLA_VTI_OKEY])
461                 parms->o_key = nla_get_be32(data[IFLA_VTI_OKEY]);
462 
463         if (data[IFLA_VTI_LOCAL])
464                 parms->iph.saddr = nla_get_in_addr(data[IFLA_VTI_LOCAL]);
465 
466         if (data[IFLA_VTI_REMOTE])
467                 parms->iph.daddr = nla_get_in_addr(data[IFLA_VTI_REMOTE]);
468 
469 }
470 
471 static int vti_newlink(struct net *src_net, struct net_device *dev,
472                        struct nlattr *tb[], struct nlattr *data[])
473 {
474         struct ip_tunnel_parm parms;
475 
476         vti_netlink_parms(data, &parms);
477         return ip_tunnel_newlink(dev, tb, &parms);
478 }
479 
480 static int vti_changelink(struct net_device *dev, struct nlattr *tb[],
481                           struct nlattr *data[])
482 {
483         struct ip_tunnel_parm p;
484 
485         vti_netlink_parms(data, &p);
486         return ip_tunnel_changelink(dev, tb, &p);
487 }
488 
489 static size_t vti_get_size(const struct net_device *dev)
490 {
491         return
492                 /* IFLA_VTI_LINK */
493                 nla_total_size(4) +
494                 /* IFLA_VTI_IKEY */
495                 nla_total_size(4) +
496                 /* IFLA_VTI_OKEY */
497                 nla_total_size(4) +
498                 /* IFLA_VTI_LOCAL */
499                 nla_total_size(4) +
500                 /* IFLA_VTI_REMOTE */
501                 nla_total_size(4) +
502                 0;
503 }
504 
505 static int vti_fill_info(struct sk_buff *skb, const struct net_device *dev)
506 {
507         struct ip_tunnel *t = netdev_priv(dev);
508         struct ip_tunnel_parm *p = &t->parms;
509 
510         nla_put_u32(skb, IFLA_VTI_LINK, p->link);
511         nla_put_be32(skb, IFLA_VTI_IKEY, p->i_key);
512         nla_put_be32(skb, IFLA_VTI_OKEY, p->o_key);
513         nla_put_in_addr(skb, IFLA_VTI_LOCAL, p->iph.saddr);
514         nla_put_in_addr(skb, IFLA_VTI_REMOTE, p->iph.daddr);
515 
516         return 0;
517 }
518 
519 static const struct nla_policy vti_policy[IFLA_VTI_MAX + 1] = {
520         [IFLA_VTI_LINK]         = { .type = NLA_U32 },
521         [IFLA_VTI_IKEY]         = { .type = NLA_U32 },
522         [IFLA_VTI_OKEY]         = { .type = NLA_U32 },
523         [IFLA_VTI_LOCAL]        = { .len = FIELD_SIZEOF(struct iphdr, saddr) },
524         [IFLA_VTI_REMOTE]       = { .len = FIELD_SIZEOF(struct iphdr, daddr) },
525 };
526 
527 static struct rtnl_link_ops vti_link_ops __read_mostly = {
528         .kind           = "vti",
529         .maxtype        = IFLA_VTI_MAX,
530         .policy         = vti_policy,
531         .priv_size      = sizeof(struct ip_tunnel),
532         .setup          = vti_tunnel_setup,
533         .validate       = vti_tunnel_validate,
534         .newlink        = vti_newlink,
535         .changelink     = vti_changelink,
536         .dellink        = ip_tunnel_dellink,
537         .get_size       = vti_get_size,
538         .fill_info      = vti_fill_info,
539         .get_link_net   = ip_tunnel_get_link_net,
540 };
541 
542 static int __init vti_init(void)
543 {
544         const char *msg;
545         int err;
546 
547         pr_info("IPv4 over IPsec tunneling driver\n");
548 
549         msg = "tunnel device";
550         err = register_pernet_device(&vti_net_ops);
551         if (err < 0)
552                 goto pernet_dev_failed;
553 
554         msg = "tunnel protocols";
555         err = xfrm4_protocol_register(&vti_esp4_protocol, IPPROTO_ESP);
556         if (err < 0)
557                 goto xfrm_proto_esp_failed;
558         err = xfrm4_protocol_register(&vti_ah4_protocol, IPPROTO_AH);
559         if (err < 0)
560                 goto xfrm_proto_ah_failed;
561         err = xfrm4_protocol_register(&vti_ipcomp4_protocol, IPPROTO_COMP);
562         if (err < 0)
563                 goto xfrm_proto_comp_failed;
564 
565         msg = "netlink interface";
566         err = rtnl_link_register(&vti_link_ops);
567         if (err < 0)
568                 goto rtnl_link_failed;
569 
570         return err;
571 
572 rtnl_link_failed:
573         xfrm4_protocol_deregister(&vti_ipcomp4_protocol, IPPROTO_COMP);
574 xfrm_proto_comp_failed:
575         xfrm4_protocol_deregister(&vti_ah4_protocol, IPPROTO_AH);
576 xfrm_proto_ah_failed:
577         xfrm4_protocol_deregister(&vti_esp4_protocol, IPPROTO_ESP);
578 xfrm_proto_esp_failed:
579         unregister_pernet_device(&vti_net_ops);
580 pernet_dev_failed:
581         pr_err("vti init: failed to register %s\n", msg);
582         return err;
583 }
584 
585 static void __exit vti_fini(void)
586 {
587         rtnl_link_unregister(&vti_link_ops);
588         xfrm4_protocol_deregister(&vti_ipcomp4_protocol, IPPROTO_COMP);
589         xfrm4_protocol_deregister(&vti_ah4_protocol, IPPROTO_AH);
590         xfrm4_protocol_deregister(&vti_esp4_protocol, IPPROTO_ESP);
591         unregister_pernet_device(&vti_net_ops);
592 }
593 
594 module_init(vti_init);
595 module_exit(vti_fini);
596 MODULE_LICENSE("GPL");
597 MODULE_ALIAS_RTNL_LINK("vti");
598 MODULE_ALIAS_NETDEV("ip_vti0");
599 

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