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

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