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TOMOYO Linux Cross Reference
Linux/net/ipv4/ip_gre.c

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  1 /*
  2  *      Linux NET3:     GRE over IP protocol decoder.
  3  *
  4  *      Authors: Alexey Kuznetsov (kuznet@ms2.inr.ac.ru)
  5  *
  6  *      This program is free software; you can redistribute it and/or
  7  *      modify it under the terms of the GNU General Public License
  8  *      as published by the Free Software Foundation; either version
  9  *      2 of the License, or (at your option) any later version.
 10  *
 11  */
 12 
 13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 14 
 15 #include <linux/capability.h>
 16 #include <linux/module.h>
 17 #include <linux/types.h>
 18 #include <linux/kernel.h>
 19 #include <linux/slab.h>
 20 #include <linux/uaccess.h>
 21 #include <linux/skbuff.h>
 22 #include <linux/netdevice.h>
 23 #include <linux/in.h>
 24 #include <linux/tcp.h>
 25 #include <linux/udp.h>
 26 #include <linux/if_arp.h>
 27 #include <linux/if_vlan.h>
 28 #include <linux/init.h>
 29 #include <linux/in6.h>
 30 #include <linux/inetdevice.h>
 31 #include <linux/igmp.h>
 32 #include <linux/netfilter_ipv4.h>
 33 #include <linux/etherdevice.h>
 34 #include <linux/if_ether.h>
 35 
 36 #include <net/sock.h>
 37 #include <net/ip.h>
 38 #include <net/icmp.h>
 39 #include <net/protocol.h>
 40 #include <net/ip_tunnels.h>
 41 #include <net/arp.h>
 42 #include <net/checksum.h>
 43 #include <net/dsfield.h>
 44 #include <net/inet_ecn.h>
 45 #include <net/xfrm.h>
 46 #include <net/net_namespace.h>
 47 #include <net/netns/generic.h>
 48 #include <net/rtnetlink.h>
 49 #include <net/gre.h>
 50 #include <net/dst_metadata.h>
 51 #include <net/erspan.h>
 52 
 53 /*
 54    Problems & solutions
 55    --------------------
 56 
 57    1. The most important issue is detecting local dead loops.
 58    They would cause complete host lockup in transmit, which
 59    would be "resolved" by stack overflow or, if queueing is enabled,
 60    with infinite looping in net_bh.
 61 
 62    We cannot track such dead loops during route installation,
 63    it is infeasible task. The most general solutions would be
 64    to keep skb->encapsulation counter (sort of local ttl),
 65    and silently drop packet when it expires. It is a good
 66    solution, but it supposes maintaining new variable in ALL
 67    skb, even if no tunneling is used.
 68 
 69    Current solution: xmit_recursion breaks dead loops. This is a percpu
 70    counter, since when we enter the first ndo_xmit(), cpu migration is
 71    forbidden. We force an exit if this counter reaches RECURSION_LIMIT
 72 
 73    2. Networking dead loops would not kill routers, but would really
 74    kill network. IP hop limit plays role of "t->recursion" in this case,
 75    if we copy it from packet being encapsulated to upper header.
 76    It is very good solution, but it introduces two problems:
 77 
 78    - Routing protocols, using packets with ttl=1 (OSPF, RIP2),
 79      do not work over tunnels.
 80    - traceroute does not work. I planned to relay ICMP from tunnel,
 81      so that this problem would be solved and traceroute output
 82      would even more informative. This idea appeared to be wrong:
 83      only Linux complies to rfc1812 now (yes, guys, Linux is the only
 84      true router now :-)), all routers (at least, in neighbourhood of mine)
 85      return only 8 bytes of payload. It is the end.
 86 
 87    Hence, if we want that OSPF worked or traceroute said something reasonable,
 88    we should search for another solution.
 89 
 90    One of them is to parse packet trying to detect inner encapsulation
 91    made by our node. It is difficult or even impossible, especially,
 92    taking into account fragmentation. TO be short, ttl is not solution at all.
 93 
 94    Current solution: The solution was UNEXPECTEDLY SIMPLE.
 95    We force DF flag on tunnels with preconfigured hop limit,
 96    that is ALL. :-) Well, it does not remove the problem completely,
 97    but exponential growth of network traffic is changed to linear
 98    (branches, that exceed pmtu are pruned) and tunnel mtu
 99    rapidly degrades to value <68, where looping stops.
100    Yes, it is not good if there exists a router in the loop,
101    which does not force DF, even when encapsulating packets have DF set.
102    But it is not our problem! Nobody could accuse us, we made
103    all that we could make. Even if it is your gated who injected
104    fatal route to network, even if it were you who configured
105    fatal static route: you are innocent. :-)
106 
107    Alexey Kuznetsov.
108  */
109 
110 static bool log_ecn_error = true;
111 module_param(log_ecn_error, bool, 0644);
112 MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
113 
114 static struct rtnl_link_ops ipgre_link_ops __read_mostly;
115 static int ipgre_tunnel_init(struct net_device *dev);
116 static void erspan_build_header(struct sk_buff *skb,
117                                 u32 id, u32 index,
118                                 bool truncate, bool is_ipv4);
119 
120 static unsigned int ipgre_net_id __read_mostly;
121 static unsigned int gre_tap_net_id __read_mostly;
122 static unsigned int erspan_net_id __read_mostly;
123 
124 static int ipgre_err(struct sk_buff *skb, u32 info,
125                      const struct tnl_ptk_info *tpi)
126 {
127 
128         /* All the routers (except for Linux) return only
129            8 bytes of packet payload. It means, that precise relaying of
130            ICMP in the real Internet is absolutely infeasible.
131 
132            Moreover, Cisco "wise men" put GRE key to the third word
133            in GRE header. It makes impossible maintaining even soft
134            state for keyed GRE tunnels with enabled checksum. Tell
135            them "thank you".
136 
137            Well, I wonder, rfc1812 was written by Cisco employee,
138            what the hell these idiots break standards established
139            by themselves???
140            */
141         struct net *net = dev_net(skb->dev);
142         struct ip_tunnel_net *itn;
143         const struct iphdr *iph;
144         const int type = icmp_hdr(skb)->type;
145         const int code = icmp_hdr(skb)->code;
146         unsigned int data_len = 0;
147         struct ip_tunnel *t;
148 
149         if (tpi->proto == htons(ETH_P_TEB))
150                 itn = net_generic(net, gre_tap_net_id);
151         else if (tpi->proto == htons(ETH_P_ERSPAN) ||
152                  tpi->proto == htons(ETH_P_ERSPAN2))
153                 itn = net_generic(net, erspan_net_id);
154         else
155                 itn = net_generic(net, ipgre_net_id);
156 
157         iph = (const struct iphdr *)(icmp_hdr(skb) + 1);
158         t = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
159                              iph->daddr, iph->saddr, tpi->key);
160 
161         if (!t)
162                 return -ENOENT;
163 
164         switch (type) {
165         default:
166         case ICMP_PARAMETERPROB:
167                 return 0;
168 
169         case ICMP_DEST_UNREACH:
170                 switch (code) {
171                 case ICMP_SR_FAILED:
172                 case ICMP_PORT_UNREACH:
173                         /* Impossible event. */
174                         return 0;
175                 default:
176                         /* All others are translated to HOST_UNREACH.
177                            rfc2003 contains "deep thoughts" about NET_UNREACH,
178                            I believe they are just ether pollution. --ANK
179                          */
180                         break;
181                 }
182                 break;
183 
184         case ICMP_TIME_EXCEEDED:
185                 if (code != ICMP_EXC_TTL)
186                         return 0;
187                 data_len = icmp_hdr(skb)->un.reserved[1] * 4; /* RFC 4884 4.1 */
188                 break;
189 
190         case ICMP_REDIRECT:
191                 break;
192         }
193 
194 #if IS_ENABLED(CONFIG_IPV6)
195        if (tpi->proto == htons(ETH_P_IPV6) &&
196            !ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4 + tpi->hdr_len,
197                                        type, data_len))
198                return 0;
199 #endif
200 
201         if (t->parms.iph.daddr == 0 ||
202             ipv4_is_multicast(t->parms.iph.daddr))
203                 return 0;
204 
205         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
206                 return 0;
207 
208         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
209                 t->err_count++;
210         else
211                 t->err_count = 1;
212         t->err_time = jiffies;
213 
214         return 0;
215 }
216 
217 static void gre_err(struct sk_buff *skb, u32 info)
218 {
219         /* All the routers (except for Linux) return only
220          * 8 bytes of packet payload. It means, that precise relaying of
221          * ICMP in the real Internet is absolutely infeasible.
222          *
223          * Moreover, Cisco "wise men" put GRE key to the third word
224          * in GRE header. It makes impossible maintaining even soft
225          * state for keyed
226          * GRE tunnels with enabled checksum. Tell them "thank you".
227          *
228          * Well, I wonder, rfc1812 was written by Cisco employee,
229          * what the hell these idiots break standards established
230          * by themselves???
231          */
232 
233         const struct iphdr *iph = (struct iphdr *)skb->data;
234         const int type = icmp_hdr(skb)->type;
235         const int code = icmp_hdr(skb)->code;
236         struct tnl_ptk_info tpi;
237 
238         if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IP),
239                              iph->ihl * 4) < 0)
240                 return;
241 
242         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
243                 ipv4_update_pmtu(skb, dev_net(skb->dev), info,
244                                  skb->dev->ifindex, IPPROTO_GRE);
245                 return;
246         }
247         if (type == ICMP_REDIRECT) {
248                 ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex,
249                               IPPROTO_GRE);
250                 return;
251         }
252 
253         ipgre_err(skb, info, &tpi);
254 }
255 
256 static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi,
257                       int gre_hdr_len)
258 {
259         struct net *net = dev_net(skb->dev);
260         struct metadata_dst *tun_dst = NULL;
261         struct erspan_base_hdr *ershdr;
262         struct ip_tunnel_net *itn;
263         struct ip_tunnel *tunnel;
264         const struct iphdr *iph;
265         struct erspan_md2 *md2;
266         int ver;
267         int len;
268 
269         itn = net_generic(net, erspan_net_id);
270 
271         iph = ip_hdr(skb);
272         ershdr = (struct erspan_base_hdr *)(skb->data + gre_hdr_len);
273         ver = ershdr->ver;
274 
275         tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex,
276                                   tpi->flags | TUNNEL_KEY,
277                                   iph->saddr, iph->daddr, tpi->key);
278 
279         if (tunnel) {
280                 len = gre_hdr_len + erspan_hdr_len(ver);
281                 if (unlikely(!pskb_may_pull(skb, len)))
282                         return PACKET_REJECT;
283 
284                 if (__iptunnel_pull_header(skb,
285                                            len,
286                                            htons(ETH_P_TEB),
287                                            false, false) < 0)
288                         goto drop;
289 
290                 if (tunnel->collect_md) {
291                         struct erspan_metadata *pkt_md, *md;
292                         struct ip_tunnel_info *info;
293                         unsigned char *gh;
294                         __be64 tun_id;
295                         __be16 flags;
296 
297                         tpi->flags |= TUNNEL_KEY;
298                         flags = tpi->flags;
299                         tun_id = key32_to_tunnel_id(tpi->key);
300 
301                         tun_dst = ip_tun_rx_dst(skb, flags,
302                                                 tun_id, sizeof(*md));
303                         if (!tun_dst)
304                                 return PACKET_REJECT;
305 
306                         /* skb can be uncloned in __iptunnel_pull_header, so
307                          * old pkt_md is no longer valid and we need to reset
308                          * it
309                          */
310                         gh = skb_network_header(skb) +
311                              skb_network_header_len(skb);
312                         pkt_md = (struct erspan_metadata *)(gh + gre_hdr_len +
313                                                             sizeof(*ershdr));
314                         md = ip_tunnel_info_opts(&tun_dst->u.tun_info);
315                         md->version = ver;
316                         md2 = &md->u.md2;
317                         memcpy(md2, pkt_md, ver == 1 ? ERSPAN_V1_MDSIZE :
318                                                        ERSPAN_V2_MDSIZE);
319 
320                         info = &tun_dst->u.tun_info;
321                         info->key.tun_flags |= TUNNEL_ERSPAN_OPT;
322                         info->options_len = sizeof(*md);
323                 }
324 
325                 skb_reset_mac_header(skb);
326                 ip_tunnel_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);
327                 return PACKET_RCVD;
328         }
329         return PACKET_REJECT;
330 
331 drop:
332         kfree_skb(skb);
333         return PACKET_RCVD;
334 }
335 
336 static int __ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
337                        struct ip_tunnel_net *itn, int hdr_len, bool raw_proto)
338 {
339         struct metadata_dst *tun_dst = NULL;
340         const struct iphdr *iph;
341         struct ip_tunnel *tunnel;
342 
343         iph = ip_hdr(skb);
344         tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
345                                   iph->saddr, iph->daddr, tpi->key);
346 
347         if (tunnel) {
348                 if (__iptunnel_pull_header(skb, hdr_len, tpi->proto,
349                                            raw_proto, false) < 0)
350                         goto drop;
351 
352                 if (tunnel->dev->type != ARPHRD_NONE)
353                         skb_pop_mac_header(skb);
354                 else
355                         skb_reset_mac_header(skb);
356                 if (tunnel->collect_md) {
357                         __be16 flags;
358                         __be64 tun_id;
359 
360                         flags = tpi->flags & (TUNNEL_CSUM | TUNNEL_KEY);
361                         tun_id = key32_to_tunnel_id(tpi->key);
362                         tun_dst = ip_tun_rx_dst(skb, flags, tun_id, 0);
363                         if (!tun_dst)
364                                 return PACKET_REJECT;
365                 }
366 
367                 ip_tunnel_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);
368                 return PACKET_RCVD;
369         }
370         return PACKET_NEXT;
371 
372 drop:
373         kfree_skb(skb);
374         return PACKET_RCVD;
375 }
376 
377 static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
378                      int hdr_len)
379 {
380         struct net *net = dev_net(skb->dev);
381         struct ip_tunnel_net *itn;
382         int res;
383 
384         if (tpi->proto == htons(ETH_P_TEB))
385                 itn = net_generic(net, gre_tap_net_id);
386         else
387                 itn = net_generic(net, ipgre_net_id);
388 
389         res = __ipgre_rcv(skb, tpi, itn, hdr_len, false);
390         if (res == PACKET_NEXT && tpi->proto == htons(ETH_P_TEB)) {
391                 /* ipgre tunnels in collect metadata mode should receive
392                  * also ETH_P_TEB traffic.
393                  */
394                 itn = net_generic(net, ipgre_net_id);
395                 res = __ipgre_rcv(skb, tpi, itn, hdr_len, true);
396         }
397         return res;
398 }
399 
400 static int gre_rcv(struct sk_buff *skb)
401 {
402         struct tnl_ptk_info tpi;
403         bool csum_err = false;
404         int hdr_len;
405 
406 #ifdef CONFIG_NET_IPGRE_BROADCAST
407         if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
408                 /* Looped back packet, drop it! */
409                 if (rt_is_output_route(skb_rtable(skb)))
410                         goto drop;
411         }
412 #endif
413 
414         hdr_len = gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP), 0);
415         if (hdr_len < 0)
416                 goto drop;
417 
418         if (unlikely(tpi.proto == htons(ETH_P_ERSPAN) ||
419                      tpi.proto == htons(ETH_P_ERSPAN2))) {
420                 if (erspan_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
421                         return 0;
422                 goto out;
423         }
424 
425         if (ipgre_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
426                 return 0;
427 
428 out:
429         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
430 drop:
431         kfree_skb(skb);
432         return 0;
433 }
434 
435 static void __gre_xmit(struct sk_buff *skb, struct net_device *dev,
436                        const struct iphdr *tnl_params,
437                        __be16 proto)
438 {
439         struct ip_tunnel *tunnel = netdev_priv(dev);
440 
441         if (tunnel->parms.o_flags & TUNNEL_SEQ)
442                 tunnel->o_seqno++;
443 
444         /* Push GRE header. */
445         gre_build_header(skb, tunnel->tun_hlen,
446                          tunnel->parms.o_flags, proto, tunnel->parms.o_key,
447                          htonl(tunnel->o_seqno));
448 
449         ip_tunnel_xmit(skb, dev, tnl_params, tnl_params->protocol);
450 }
451 
452 static int gre_handle_offloads(struct sk_buff *skb, bool csum)
453 {
454         return iptunnel_handle_offloads(skb, csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE);
455 }
456 
457 static struct rtable *gre_get_rt(struct sk_buff *skb,
458                                  struct net_device *dev,
459                                  struct flowi4 *fl,
460                                  const struct ip_tunnel_key *key)
461 {
462         struct net *net = dev_net(dev);
463 
464         memset(fl, 0, sizeof(*fl));
465         fl->daddr = key->u.ipv4.dst;
466         fl->saddr = key->u.ipv4.src;
467         fl->flowi4_tos = RT_TOS(key->tos);
468         fl->flowi4_mark = skb->mark;
469         fl->flowi4_proto = IPPROTO_GRE;
470 
471         return ip_route_output_key(net, fl);
472 }
473 
474 static struct rtable *prepare_fb_xmit(struct sk_buff *skb,
475                                       struct net_device *dev,
476                                       struct flowi4 *fl,
477                                       int tunnel_hlen)
478 {
479         struct ip_tunnel_info *tun_info;
480         const struct ip_tunnel_key *key;
481         struct rtable *rt = NULL;
482         int min_headroom;
483         bool use_cache;
484         int err;
485 
486         tun_info = skb_tunnel_info(skb);
487         key = &tun_info->key;
488         use_cache = ip_tunnel_dst_cache_usable(skb, tun_info);
489 
490         if (use_cache)
491                 rt = dst_cache_get_ip4(&tun_info->dst_cache, &fl->saddr);
492         if (!rt) {
493                 rt = gre_get_rt(skb, dev, fl, key);
494                 if (IS_ERR(rt))
495                         goto err_free_skb;
496                 if (use_cache)
497                         dst_cache_set_ip4(&tun_info->dst_cache, &rt->dst,
498                                           fl->saddr);
499         }
500 
501         min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
502                         + tunnel_hlen + sizeof(struct iphdr);
503         if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
504                 int head_delta = SKB_DATA_ALIGN(min_headroom -
505                                                 skb_headroom(skb) +
506                                                 16);
507                 err = pskb_expand_head(skb, max_t(int, head_delta, 0),
508                                        0, GFP_ATOMIC);
509                 if (unlikely(err))
510                         goto err_free_rt;
511         }
512         return rt;
513 
514 err_free_rt:
515         ip_rt_put(rt);
516 err_free_skb:
517         kfree_skb(skb);
518         dev->stats.tx_dropped++;
519         return NULL;
520 }
521 
522 static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev,
523                         __be16 proto)
524 {
525         struct ip_tunnel *tunnel = netdev_priv(dev);
526         struct ip_tunnel_info *tun_info;
527         const struct ip_tunnel_key *key;
528         struct rtable *rt = NULL;
529         struct flowi4 fl;
530         int tunnel_hlen;
531         __be16 df, flags;
532 
533         tun_info = skb_tunnel_info(skb);
534         if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
535                      ip_tunnel_info_af(tun_info) != AF_INET))
536                 goto err_free_skb;
537 
538         key = &tun_info->key;
539         tunnel_hlen = gre_calc_hlen(key->tun_flags);
540 
541         rt = prepare_fb_xmit(skb, dev, &fl, tunnel_hlen);
542         if (!rt)
543                 return;
544 
545         /* Push Tunnel header. */
546         if (gre_handle_offloads(skb, !!(tun_info->key.tun_flags & TUNNEL_CSUM)))
547                 goto err_free_rt;
548 
549         flags = tun_info->key.tun_flags &
550                 (TUNNEL_CSUM | TUNNEL_KEY | TUNNEL_SEQ);
551         gre_build_header(skb, tunnel_hlen, flags, proto,
552                          tunnel_id_to_key32(tun_info->key.tun_id),
553                          (flags & TUNNEL_SEQ) ? htonl(tunnel->o_seqno++) : 0);
554 
555         df = key->tun_flags & TUNNEL_DONT_FRAGMENT ?  htons(IP_DF) : 0;
556 
557         iptunnel_xmit(skb->sk, rt, skb, fl.saddr, key->u.ipv4.dst, IPPROTO_GRE,
558                       key->tos, key->ttl, df, false);
559         return;
560 
561 err_free_rt:
562         ip_rt_put(rt);
563 err_free_skb:
564         kfree_skb(skb);
565         dev->stats.tx_dropped++;
566 }
567 
568 static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev)
569 {
570         struct ip_tunnel *tunnel = netdev_priv(dev);
571         struct ip_tunnel_info *tun_info;
572         const struct ip_tunnel_key *key;
573         struct erspan_metadata *md;
574         struct rtable *rt = NULL;
575         bool truncate = false;
576         __be16 df, proto;
577         struct flowi4 fl;
578         int tunnel_hlen;
579         int version;
580         int nhoff;
581         int thoff;
582 
583         tun_info = skb_tunnel_info(skb);
584         if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
585                      ip_tunnel_info_af(tun_info) != AF_INET))
586                 goto err_free_skb;
587 
588         key = &tun_info->key;
589         if (!(tun_info->key.tun_flags & TUNNEL_ERSPAN_OPT))
590                 goto err_free_rt;
591         md = ip_tunnel_info_opts(tun_info);
592         if (!md)
593                 goto err_free_rt;
594 
595         /* ERSPAN has fixed 8 byte GRE header */
596         version = md->version;
597         tunnel_hlen = 8 + erspan_hdr_len(version);
598 
599         rt = prepare_fb_xmit(skb, dev, &fl, tunnel_hlen);
600         if (!rt)
601                 return;
602 
603         if (gre_handle_offloads(skb, false))
604                 goto err_free_rt;
605 
606         if (skb->len > dev->mtu + dev->hard_header_len) {
607                 pskb_trim(skb, dev->mtu + dev->hard_header_len);
608                 truncate = true;
609         }
610 
611         nhoff = skb_network_header(skb) - skb_mac_header(skb);
612         if (skb->protocol == htons(ETH_P_IP) &&
613             (ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff))
614                 truncate = true;
615 
616         thoff = skb_transport_header(skb) - skb_mac_header(skb);
617         if (skb->protocol == htons(ETH_P_IPV6) &&
618             (ntohs(ipv6_hdr(skb)->payload_len) > skb->len - thoff))
619                 truncate = true;
620 
621         if (version == 1) {
622                 erspan_build_header(skb, ntohl(tunnel_id_to_key32(key->tun_id)),
623                                     ntohl(md->u.index), truncate, true);
624                 proto = htons(ETH_P_ERSPAN);
625         } else if (version == 2) {
626                 erspan_build_header_v2(skb,
627                                        ntohl(tunnel_id_to_key32(key->tun_id)),
628                                        md->u.md2.dir,
629                                        get_hwid(&md->u.md2),
630                                        truncate, true);
631                 proto = htons(ETH_P_ERSPAN2);
632         } else {
633                 goto err_free_rt;
634         }
635 
636         gre_build_header(skb, 8, TUNNEL_SEQ,
637                          proto, 0, htonl(tunnel->o_seqno++));
638 
639         df = key->tun_flags & TUNNEL_DONT_FRAGMENT ?  htons(IP_DF) : 0;
640 
641         iptunnel_xmit(skb->sk, rt, skb, fl.saddr, key->u.ipv4.dst, IPPROTO_GRE,
642                       key->tos, key->ttl, df, false);
643         return;
644 
645 err_free_rt:
646         ip_rt_put(rt);
647 err_free_skb:
648         kfree_skb(skb);
649         dev->stats.tx_dropped++;
650 }
651 
652 static int gre_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
653 {
654         struct ip_tunnel_info *info = skb_tunnel_info(skb);
655         struct rtable *rt;
656         struct flowi4 fl4;
657 
658         if (ip_tunnel_info_af(info) != AF_INET)
659                 return -EINVAL;
660 
661         rt = gre_get_rt(skb, dev, &fl4, &info->key);
662         if (IS_ERR(rt))
663                 return PTR_ERR(rt);
664 
665         ip_rt_put(rt);
666         info->key.u.ipv4.src = fl4.saddr;
667         return 0;
668 }
669 
670 static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
671                               struct net_device *dev)
672 {
673         struct ip_tunnel *tunnel = netdev_priv(dev);
674         const struct iphdr *tnl_params;
675 
676         if (!pskb_inet_may_pull(skb))
677                 goto free_skb;
678 
679         if (tunnel->collect_md) {
680                 gre_fb_xmit(skb, dev, skb->protocol);
681                 return NETDEV_TX_OK;
682         }
683 
684         if (dev->header_ops) {
685                 /* Need space for new headers */
686                 if (skb_cow_head(skb, dev->needed_headroom -
687                                       (tunnel->hlen + sizeof(struct iphdr))))
688                         goto free_skb;
689 
690                 tnl_params = (const struct iphdr *)skb->data;
691 
692                 /* Pull skb since ip_tunnel_xmit() needs skb->data pointing
693                  * to gre header.
694                  */
695                 skb_pull(skb, tunnel->hlen + sizeof(struct iphdr));
696                 skb_reset_mac_header(skb);
697         } else {
698                 if (skb_cow_head(skb, dev->needed_headroom))
699                         goto free_skb;
700 
701                 tnl_params = &tunnel->parms.iph;
702         }
703 
704         if (gre_handle_offloads(skb, !!(tunnel->parms.o_flags & TUNNEL_CSUM)))
705                 goto free_skb;
706 
707         __gre_xmit(skb, dev, tnl_params, skb->protocol);
708         return NETDEV_TX_OK;
709 
710 free_skb:
711         kfree_skb(skb);
712         dev->stats.tx_dropped++;
713         return NETDEV_TX_OK;
714 }
715 
716 static netdev_tx_t erspan_xmit(struct sk_buff *skb,
717                                struct net_device *dev)
718 {
719         struct ip_tunnel *tunnel = netdev_priv(dev);
720         bool truncate = false;
721         __be16 proto;
722 
723         if (!pskb_inet_may_pull(skb))
724                 goto free_skb;
725 
726         if (tunnel->collect_md) {
727                 erspan_fb_xmit(skb, dev);
728                 return NETDEV_TX_OK;
729         }
730 
731         if (gre_handle_offloads(skb, false))
732                 goto free_skb;
733 
734         if (skb_cow_head(skb, dev->needed_headroom))
735                 goto free_skb;
736 
737         if (skb->len > dev->mtu + dev->hard_header_len) {
738                 pskb_trim(skb, dev->mtu + dev->hard_header_len);
739                 truncate = true;
740         }
741 
742         /* Push ERSPAN header */
743         if (tunnel->erspan_ver == 1) {
744                 erspan_build_header(skb, ntohl(tunnel->parms.o_key),
745                                     tunnel->index,
746                                     truncate, true);
747                 proto = htons(ETH_P_ERSPAN);
748         } else if (tunnel->erspan_ver == 2) {
749                 erspan_build_header_v2(skb, ntohl(tunnel->parms.o_key),
750                                        tunnel->dir, tunnel->hwid,
751                                        truncate, true);
752                 proto = htons(ETH_P_ERSPAN2);
753         } else {
754                 goto free_skb;
755         }
756 
757         tunnel->parms.o_flags &= ~TUNNEL_KEY;
758         __gre_xmit(skb, dev, &tunnel->parms.iph, proto);
759         return NETDEV_TX_OK;
760 
761 free_skb:
762         kfree_skb(skb);
763         dev->stats.tx_dropped++;
764         return NETDEV_TX_OK;
765 }
766 
767 static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,
768                                 struct net_device *dev)
769 {
770         struct ip_tunnel *tunnel = netdev_priv(dev);
771 
772         if (!pskb_inet_may_pull(skb))
773                 goto free_skb;
774 
775         if (tunnel->collect_md) {
776                 gre_fb_xmit(skb, dev, htons(ETH_P_TEB));
777                 return NETDEV_TX_OK;
778         }
779 
780         if (gre_handle_offloads(skb, !!(tunnel->parms.o_flags & TUNNEL_CSUM)))
781                 goto free_skb;
782 
783         if (skb_cow_head(skb, dev->needed_headroom))
784                 goto free_skb;
785 
786         __gre_xmit(skb, dev, &tunnel->parms.iph, htons(ETH_P_TEB));
787         return NETDEV_TX_OK;
788 
789 free_skb:
790         kfree_skb(skb);
791         dev->stats.tx_dropped++;
792         return NETDEV_TX_OK;
793 }
794 
795 static void ipgre_link_update(struct net_device *dev, bool set_mtu)
796 {
797         struct ip_tunnel *tunnel = netdev_priv(dev);
798         int len;
799 
800         len = tunnel->tun_hlen;
801         tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
802         len = tunnel->tun_hlen - len;
803         tunnel->hlen = tunnel->hlen + len;
804 
805         dev->needed_headroom = dev->needed_headroom + len;
806         if (set_mtu)
807                 dev->mtu = max_t(int, dev->mtu - len, 68);
808 
809         if (!(tunnel->parms.o_flags & TUNNEL_SEQ)) {
810                 if (!(tunnel->parms.o_flags & TUNNEL_CSUM) ||
811                     tunnel->encap.type == TUNNEL_ENCAP_NONE) {
812                         dev->features |= NETIF_F_GSO_SOFTWARE;
813                         dev->hw_features |= NETIF_F_GSO_SOFTWARE;
814                 } else {
815                         dev->features &= ~NETIF_F_GSO_SOFTWARE;
816                         dev->hw_features &= ~NETIF_F_GSO_SOFTWARE;
817                 }
818                 dev->features |= NETIF_F_LLTX;
819         } else {
820                 dev->hw_features &= ~NETIF_F_GSO_SOFTWARE;
821                 dev->features &= ~(NETIF_F_LLTX | NETIF_F_GSO_SOFTWARE);
822         }
823 }
824 
825 static int ipgre_tunnel_ioctl(struct net_device *dev,
826                               struct ifreq *ifr, int cmd)
827 {
828         struct ip_tunnel_parm p;
829         int err;
830 
831         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
832                 return -EFAULT;
833 
834         if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
835                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_GRE ||
836                     p.iph.ihl != 5 || (p.iph.frag_off & htons(~IP_DF)) ||
837                     ((p.i_flags | p.o_flags) & (GRE_VERSION | GRE_ROUTING)))
838                         return -EINVAL;
839         }
840 
841         p.i_flags = gre_flags_to_tnl_flags(p.i_flags);
842         p.o_flags = gre_flags_to_tnl_flags(p.o_flags);
843 
844         err = ip_tunnel_ioctl(dev, &p, cmd);
845         if (err)
846                 return err;
847 
848         if (cmd == SIOCCHGTUNNEL) {
849                 struct ip_tunnel *t = netdev_priv(dev);
850 
851                 t->parms.i_flags = p.i_flags;
852                 t->parms.o_flags = p.o_flags;
853 
854                 if (strcmp(dev->rtnl_link_ops->kind, "erspan"))
855                         ipgre_link_update(dev, true);
856         }
857 
858         p.i_flags = gre_tnl_flags_to_gre_flags(p.i_flags);
859         p.o_flags = gre_tnl_flags_to_gre_flags(p.o_flags);
860 
861         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
862                 return -EFAULT;
863 
864         return 0;
865 }
866 
867 /* Nice toy. Unfortunately, useless in real life :-)
868    It allows to construct virtual multiprotocol broadcast "LAN"
869    over the Internet, provided multicast routing is tuned.
870 
871 
872    I have no idea was this bicycle invented before me,
873    so that I had to set ARPHRD_IPGRE to a random value.
874    I have an impression, that Cisco could make something similar,
875    but this feature is apparently missing in IOS<=11.2(8).
876 
877    I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks
878    with broadcast 224.66.66.66. If you have access to mbone, play with me :-)
879 
880    ping -t 255 224.66.66.66
881 
882    If nobody answers, mbone does not work.
883 
884    ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255
885    ip addr add 10.66.66.<somewhat>/24 dev Universe
886    ifconfig Universe up
887    ifconfig Universe add fe80::<Your_real_addr>/10
888    ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96
889    ftp 10.66.66.66
890    ...
891    ftp fec0:6666:6666::193.233.7.65
892    ...
893  */
894 static int ipgre_header(struct sk_buff *skb, struct net_device *dev,
895                         unsigned short type,
896                         const void *daddr, const void *saddr, unsigned int len)
897 {
898         struct ip_tunnel *t = netdev_priv(dev);
899         struct iphdr *iph;
900         struct gre_base_hdr *greh;
901 
902         iph = skb_push(skb, t->hlen + sizeof(*iph));
903         greh = (struct gre_base_hdr *)(iph+1);
904         greh->flags = gre_tnl_flags_to_gre_flags(t->parms.o_flags);
905         greh->protocol = htons(type);
906 
907         memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
908 
909         /* Set the source hardware address. */
910         if (saddr)
911                 memcpy(&iph->saddr, saddr, 4);
912         if (daddr)
913                 memcpy(&iph->daddr, daddr, 4);
914         if (iph->daddr)
915                 return t->hlen + sizeof(*iph);
916 
917         return -(t->hlen + sizeof(*iph));
918 }
919 
920 static int ipgre_header_parse(const struct sk_buff *skb, unsigned char *haddr)
921 {
922         const struct iphdr *iph = (const struct iphdr *) skb_mac_header(skb);
923         memcpy(haddr, &iph->saddr, 4);
924         return 4;
925 }
926 
927 static const struct header_ops ipgre_header_ops = {
928         .create = ipgre_header,
929         .parse  = ipgre_header_parse,
930 };
931 
932 #ifdef CONFIG_NET_IPGRE_BROADCAST
933 static int ipgre_open(struct net_device *dev)
934 {
935         struct ip_tunnel *t = netdev_priv(dev);
936 
937         if (ipv4_is_multicast(t->parms.iph.daddr)) {
938                 struct flowi4 fl4;
939                 struct rtable *rt;
940 
941                 rt = ip_route_output_gre(t->net, &fl4,
942                                          t->parms.iph.daddr,
943                                          t->parms.iph.saddr,
944                                          t->parms.o_key,
945                                          RT_TOS(t->parms.iph.tos),
946                                          t->parms.link);
947                 if (IS_ERR(rt))
948                         return -EADDRNOTAVAIL;
949                 dev = rt->dst.dev;
950                 ip_rt_put(rt);
951                 if (!__in_dev_get_rtnl(dev))
952                         return -EADDRNOTAVAIL;
953                 t->mlink = dev->ifindex;
954                 ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);
955         }
956         return 0;
957 }
958 
959 static int ipgre_close(struct net_device *dev)
960 {
961         struct ip_tunnel *t = netdev_priv(dev);
962 
963         if (ipv4_is_multicast(t->parms.iph.daddr) && t->mlink) {
964                 struct in_device *in_dev;
965                 in_dev = inetdev_by_index(t->net, t->mlink);
966                 if (in_dev)
967                         ip_mc_dec_group(in_dev, t->parms.iph.daddr);
968         }
969         return 0;
970 }
971 #endif
972 
973 static const struct net_device_ops ipgre_netdev_ops = {
974         .ndo_init               = ipgre_tunnel_init,
975         .ndo_uninit             = ip_tunnel_uninit,
976 #ifdef CONFIG_NET_IPGRE_BROADCAST
977         .ndo_open               = ipgre_open,
978         .ndo_stop               = ipgre_close,
979 #endif
980         .ndo_start_xmit         = ipgre_xmit,
981         .ndo_do_ioctl           = ipgre_tunnel_ioctl,
982         .ndo_change_mtu         = ip_tunnel_change_mtu,
983         .ndo_get_stats64        = ip_tunnel_get_stats64,
984         .ndo_get_iflink         = ip_tunnel_get_iflink,
985 };
986 
987 #define GRE_FEATURES (NETIF_F_SG |              \
988                       NETIF_F_FRAGLIST |        \
989                       NETIF_F_HIGHDMA |         \
990                       NETIF_F_HW_CSUM)
991 
992 static void ipgre_tunnel_setup(struct net_device *dev)
993 {
994         dev->netdev_ops         = &ipgre_netdev_ops;
995         dev->type               = ARPHRD_IPGRE;
996         ip_tunnel_setup(dev, ipgre_net_id);
997 }
998 
999 static void __gre_tunnel_init(struct net_device *dev)
1000 {
1001         struct ip_tunnel *tunnel;
1002 
1003         tunnel = netdev_priv(dev);
1004         tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
1005         tunnel->parms.iph.protocol = IPPROTO_GRE;
1006 
1007         tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;
1008 
1009         dev->features           |= GRE_FEATURES;
1010         dev->hw_features        |= GRE_FEATURES;
1011 
1012         if (!(tunnel->parms.o_flags & TUNNEL_SEQ)) {
1013                 /* TCP offload with GRE SEQ is not supported, nor
1014                  * can we support 2 levels of outer headers requiring
1015                  * an update.
1016                  */
1017                 if (!(tunnel->parms.o_flags & TUNNEL_CSUM) ||
1018                     (tunnel->encap.type == TUNNEL_ENCAP_NONE)) {
1019                         dev->features    |= NETIF_F_GSO_SOFTWARE;
1020                         dev->hw_features |= NETIF_F_GSO_SOFTWARE;
1021                 }
1022 
1023                 /* Can use a lockless transmit, unless we generate
1024                  * output sequences
1025                  */
1026                 dev->features |= NETIF_F_LLTX;
1027         }
1028 }
1029 
1030 static int ipgre_tunnel_init(struct net_device *dev)
1031 {
1032         struct ip_tunnel *tunnel = netdev_priv(dev);
1033         struct iphdr *iph = &tunnel->parms.iph;
1034 
1035         __gre_tunnel_init(dev);
1036 
1037         memcpy(dev->dev_addr, &iph->saddr, 4);
1038         memcpy(dev->broadcast, &iph->daddr, 4);
1039 
1040         dev->flags              = IFF_NOARP;
1041         netif_keep_dst(dev);
1042         dev->addr_len           = 4;
1043 
1044         if (iph->daddr && !tunnel->collect_md) {
1045 #ifdef CONFIG_NET_IPGRE_BROADCAST
1046                 if (ipv4_is_multicast(iph->daddr)) {
1047                         if (!iph->saddr)
1048                                 return -EINVAL;
1049                         dev->flags = IFF_BROADCAST;
1050                         dev->header_ops = &ipgre_header_ops;
1051                 }
1052 #endif
1053         } else if (!tunnel->collect_md) {
1054                 dev->header_ops = &ipgre_header_ops;
1055         }
1056 
1057         return ip_tunnel_init(dev);
1058 }
1059 
1060 static const struct gre_protocol ipgre_protocol = {
1061         .handler     = gre_rcv,
1062         .err_handler = gre_err,
1063 };
1064 
1065 static int __net_init ipgre_init_net(struct net *net)
1066 {
1067         return ip_tunnel_init_net(net, ipgre_net_id, &ipgre_link_ops, NULL);
1068 }
1069 
1070 static void __net_exit ipgre_exit_batch_net(struct list_head *list_net)
1071 {
1072         ip_tunnel_delete_nets(list_net, ipgre_net_id, &ipgre_link_ops);
1073 }
1074 
1075 static struct pernet_operations ipgre_net_ops = {
1076         .init = ipgre_init_net,
1077         .exit_batch = ipgre_exit_batch_net,
1078         .id   = &ipgre_net_id,
1079         .size = sizeof(struct ip_tunnel_net),
1080 };
1081 
1082 static int ipgre_tunnel_validate(struct nlattr *tb[], struct nlattr *data[],
1083                                  struct netlink_ext_ack *extack)
1084 {
1085         __be16 flags;
1086 
1087         if (!data)
1088                 return 0;
1089 
1090         flags = 0;
1091         if (data[IFLA_GRE_IFLAGS])
1092                 flags |= nla_get_be16(data[IFLA_GRE_IFLAGS]);
1093         if (data[IFLA_GRE_OFLAGS])
1094                 flags |= nla_get_be16(data[IFLA_GRE_OFLAGS]);
1095         if (flags & (GRE_VERSION|GRE_ROUTING))
1096                 return -EINVAL;
1097 
1098         if (data[IFLA_GRE_COLLECT_METADATA] &&
1099             data[IFLA_GRE_ENCAP_TYPE] &&
1100             nla_get_u16(data[IFLA_GRE_ENCAP_TYPE]) != TUNNEL_ENCAP_NONE)
1101                 return -EINVAL;
1102 
1103         return 0;
1104 }
1105 
1106 static int ipgre_tap_validate(struct nlattr *tb[], struct nlattr *data[],
1107                               struct netlink_ext_ack *extack)
1108 {
1109         __be32 daddr;
1110 
1111         if (tb[IFLA_ADDRESS]) {
1112                 if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
1113                         return -EINVAL;
1114                 if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
1115                         return -EADDRNOTAVAIL;
1116         }
1117 
1118         if (!data)
1119                 goto out;
1120 
1121         if (data[IFLA_GRE_REMOTE]) {
1122                 memcpy(&daddr, nla_data(data[IFLA_GRE_REMOTE]), 4);
1123                 if (!daddr)
1124                         return -EINVAL;
1125         }
1126 
1127 out:
1128         return ipgre_tunnel_validate(tb, data, extack);
1129 }
1130 
1131 static int erspan_validate(struct nlattr *tb[], struct nlattr *data[],
1132                            struct netlink_ext_ack *extack)
1133 {
1134         __be16 flags = 0;
1135         int ret;
1136 
1137         if (!data)
1138                 return 0;
1139 
1140         ret = ipgre_tap_validate(tb, data, extack);
1141         if (ret)
1142                 return ret;
1143 
1144         /* ERSPAN should only have GRE sequence and key flag */
1145         if (data[IFLA_GRE_OFLAGS])
1146                 flags |= nla_get_be16(data[IFLA_GRE_OFLAGS]);
1147         if (data[IFLA_GRE_IFLAGS])
1148                 flags |= nla_get_be16(data[IFLA_GRE_IFLAGS]);
1149         if (!data[IFLA_GRE_COLLECT_METADATA] &&
1150             flags != (GRE_SEQ | GRE_KEY))
1151                 return -EINVAL;
1152 
1153         /* ERSPAN Session ID only has 10-bit. Since we reuse
1154          * 32-bit key field as ID, check it's range.
1155          */
1156         if (data[IFLA_GRE_IKEY] &&
1157             (ntohl(nla_get_be32(data[IFLA_GRE_IKEY])) & ~ID_MASK))
1158                 return -EINVAL;
1159 
1160         if (data[IFLA_GRE_OKEY] &&
1161             (ntohl(nla_get_be32(data[IFLA_GRE_OKEY])) & ~ID_MASK))
1162                 return -EINVAL;
1163 
1164         return 0;
1165 }
1166 
1167 static int ipgre_netlink_parms(struct net_device *dev,
1168                                 struct nlattr *data[],
1169                                 struct nlattr *tb[],
1170                                 struct ip_tunnel_parm *parms,
1171                                 __u32 *fwmark)
1172 {
1173         struct ip_tunnel *t = netdev_priv(dev);
1174 
1175         memset(parms, 0, sizeof(*parms));
1176 
1177         parms->iph.protocol = IPPROTO_GRE;
1178 
1179         if (!data)
1180                 return 0;
1181 
1182         if (data[IFLA_GRE_LINK])
1183                 parms->link = nla_get_u32(data[IFLA_GRE_LINK]);
1184 
1185         if (data[IFLA_GRE_IFLAGS])
1186                 parms->i_flags = gre_flags_to_tnl_flags(nla_get_be16(data[IFLA_GRE_IFLAGS]));
1187 
1188         if (data[IFLA_GRE_OFLAGS])
1189                 parms->o_flags = gre_flags_to_tnl_flags(nla_get_be16(data[IFLA_GRE_OFLAGS]));
1190 
1191         if (data[IFLA_GRE_IKEY])
1192                 parms->i_key = nla_get_be32(data[IFLA_GRE_IKEY]);
1193 
1194         if (data[IFLA_GRE_OKEY])
1195                 parms->o_key = nla_get_be32(data[IFLA_GRE_OKEY]);
1196 
1197         if (data[IFLA_GRE_LOCAL])
1198                 parms->iph.saddr = nla_get_in_addr(data[IFLA_GRE_LOCAL]);
1199 
1200         if (data[IFLA_GRE_REMOTE])
1201                 parms->iph.daddr = nla_get_in_addr(data[IFLA_GRE_REMOTE]);
1202 
1203         if (data[IFLA_GRE_TTL])
1204                 parms->iph.ttl = nla_get_u8(data[IFLA_GRE_TTL]);
1205 
1206         if (data[IFLA_GRE_TOS])
1207                 parms->iph.tos = nla_get_u8(data[IFLA_GRE_TOS]);
1208 
1209         if (!data[IFLA_GRE_PMTUDISC] || nla_get_u8(data[IFLA_GRE_PMTUDISC])) {
1210                 if (t->ignore_df)
1211                         return -EINVAL;
1212                 parms->iph.frag_off = htons(IP_DF);
1213         }
1214 
1215         if (data[IFLA_GRE_COLLECT_METADATA]) {
1216                 t->collect_md = true;
1217                 if (dev->type == ARPHRD_IPGRE)
1218                         dev->type = ARPHRD_NONE;
1219         }
1220 
1221         if (data[IFLA_GRE_IGNORE_DF]) {
1222                 if (nla_get_u8(data[IFLA_GRE_IGNORE_DF])
1223                   && (parms->iph.frag_off & htons(IP_DF)))
1224                         return -EINVAL;
1225                 t->ignore_df = !!nla_get_u8(data[IFLA_GRE_IGNORE_DF]);
1226         }
1227 
1228         if (data[IFLA_GRE_FWMARK])
1229                 *fwmark = nla_get_u32(data[IFLA_GRE_FWMARK]);
1230 
1231         if (data[IFLA_GRE_ERSPAN_VER]) {
1232                 t->erspan_ver = nla_get_u8(data[IFLA_GRE_ERSPAN_VER]);
1233 
1234                 if (t->erspan_ver != 1 && t->erspan_ver != 2)
1235                         return -EINVAL;
1236         }
1237 
1238         if (t->erspan_ver == 1) {
1239                 if (data[IFLA_GRE_ERSPAN_INDEX]) {
1240                         t->index = nla_get_u32(data[IFLA_GRE_ERSPAN_INDEX]);
1241                         if (t->index & ~INDEX_MASK)
1242                                 return -EINVAL;
1243                 }
1244         } else if (t->erspan_ver == 2) {
1245                 if (data[IFLA_GRE_ERSPAN_DIR]) {
1246                         t->dir = nla_get_u8(data[IFLA_GRE_ERSPAN_DIR]);
1247                         if (t->dir & ~(DIR_MASK >> DIR_OFFSET))
1248                                 return -EINVAL;
1249                 }
1250                 if (data[IFLA_GRE_ERSPAN_HWID]) {
1251                         t->hwid = nla_get_u16(data[IFLA_GRE_ERSPAN_HWID]);
1252                         if (t->hwid & ~(HWID_MASK >> HWID_OFFSET))
1253                                 return -EINVAL;
1254                 }
1255         }
1256 
1257         return 0;
1258 }
1259 
1260 /* This function returns true when ENCAP attributes are present in the nl msg */
1261 static bool ipgre_netlink_encap_parms(struct nlattr *data[],
1262                                       struct ip_tunnel_encap *ipencap)
1263 {
1264         bool ret = false;
1265 
1266         memset(ipencap, 0, sizeof(*ipencap));
1267 
1268         if (!data)
1269                 return ret;
1270 
1271         if (data[IFLA_GRE_ENCAP_TYPE]) {
1272                 ret = true;
1273                 ipencap->type = nla_get_u16(data[IFLA_GRE_ENCAP_TYPE]);
1274         }
1275 
1276         if (data[IFLA_GRE_ENCAP_FLAGS]) {
1277                 ret = true;
1278                 ipencap->flags = nla_get_u16(data[IFLA_GRE_ENCAP_FLAGS]);
1279         }
1280 
1281         if (data[IFLA_GRE_ENCAP_SPORT]) {
1282                 ret = true;
1283                 ipencap->sport = nla_get_be16(data[IFLA_GRE_ENCAP_SPORT]);
1284         }
1285 
1286         if (data[IFLA_GRE_ENCAP_DPORT]) {
1287                 ret = true;
1288                 ipencap->dport = nla_get_be16(data[IFLA_GRE_ENCAP_DPORT]);
1289         }
1290 
1291         return ret;
1292 }
1293 
1294 static int gre_tap_init(struct net_device *dev)
1295 {
1296         __gre_tunnel_init(dev);
1297         dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
1298         netif_keep_dst(dev);
1299 
1300         return ip_tunnel_init(dev);
1301 }
1302 
1303 static const struct net_device_ops gre_tap_netdev_ops = {
1304         .ndo_init               = gre_tap_init,
1305         .ndo_uninit             = ip_tunnel_uninit,
1306         .ndo_start_xmit         = gre_tap_xmit,
1307         .ndo_set_mac_address    = eth_mac_addr,
1308         .ndo_validate_addr      = eth_validate_addr,
1309         .ndo_change_mtu         = ip_tunnel_change_mtu,
1310         .ndo_get_stats64        = ip_tunnel_get_stats64,
1311         .ndo_get_iflink         = ip_tunnel_get_iflink,
1312         .ndo_fill_metadata_dst  = gre_fill_metadata_dst,
1313 };
1314 
1315 static int erspan_tunnel_init(struct net_device *dev)
1316 {
1317         struct ip_tunnel *tunnel = netdev_priv(dev);
1318 
1319         tunnel->tun_hlen = 8;
1320         tunnel->parms.iph.protocol = IPPROTO_GRE;
1321         tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen +
1322                        erspan_hdr_len(tunnel->erspan_ver);
1323 
1324         dev->features           |= GRE_FEATURES;
1325         dev->hw_features        |= GRE_FEATURES;
1326         dev->priv_flags         |= IFF_LIVE_ADDR_CHANGE;
1327         netif_keep_dst(dev);
1328 
1329         return ip_tunnel_init(dev);
1330 }
1331 
1332 static const struct net_device_ops erspan_netdev_ops = {
1333         .ndo_init               = erspan_tunnel_init,
1334         .ndo_uninit             = ip_tunnel_uninit,
1335         .ndo_start_xmit         = erspan_xmit,
1336         .ndo_set_mac_address    = eth_mac_addr,
1337         .ndo_validate_addr      = eth_validate_addr,
1338         .ndo_change_mtu         = ip_tunnel_change_mtu,
1339         .ndo_get_stats64        = ip_tunnel_get_stats64,
1340         .ndo_get_iflink         = ip_tunnel_get_iflink,
1341         .ndo_fill_metadata_dst  = gre_fill_metadata_dst,
1342 };
1343 
1344 static void ipgre_tap_setup(struct net_device *dev)
1345 {
1346         ether_setup(dev);
1347         dev->max_mtu = 0;
1348         dev->netdev_ops = &gre_tap_netdev_ops;
1349         dev->priv_flags &= ~IFF_TX_SKB_SHARING;
1350         dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
1351         ip_tunnel_setup(dev, gre_tap_net_id);
1352 }
1353 
1354 static int ipgre_newlink(struct net *src_net, struct net_device *dev,
1355                          struct nlattr *tb[], struct nlattr *data[],
1356                          struct netlink_ext_ack *extack)
1357 {
1358         struct ip_tunnel_parm p;
1359         struct ip_tunnel_encap ipencap;
1360         __u32 fwmark = 0;
1361         int err;
1362 
1363         if (ipgre_netlink_encap_parms(data, &ipencap)) {
1364                 struct ip_tunnel *t = netdev_priv(dev);
1365                 err = ip_tunnel_encap_setup(t, &ipencap);
1366 
1367                 if (err < 0)
1368                         return err;
1369         }
1370 
1371         err = ipgre_netlink_parms(dev, data, tb, &p, &fwmark);
1372         if (err < 0)
1373                 return err;
1374         return ip_tunnel_newlink(dev, tb, &p, fwmark);
1375 }
1376 
1377 static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
1378                             struct nlattr *data[],
1379                             struct netlink_ext_ack *extack)
1380 {
1381         struct ip_tunnel *t = netdev_priv(dev);
1382         struct ip_tunnel_encap ipencap;
1383         __u32 fwmark = t->fwmark;
1384         struct ip_tunnel_parm p;
1385         int err;
1386 
1387         if (ipgre_netlink_encap_parms(data, &ipencap)) {
1388                 err = ip_tunnel_encap_setup(t, &ipencap);
1389 
1390                 if (err < 0)
1391                         return err;
1392         }
1393 
1394         err = ipgre_netlink_parms(dev, data, tb, &p, &fwmark);
1395         if (err < 0)
1396                 return err;
1397 
1398         err = ip_tunnel_changelink(dev, tb, &p, fwmark);
1399         if (err < 0)
1400                 return err;
1401 
1402         t->parms.i_flags = p.i_flags;
1403         t->parms.o_flags = p.o_flags;
1404 
1405         if (strcmp(dev->rtnl_link_ops->kind, "erspan"))
1406                 ipgre_link_update(dev, !tb[IFLA_MTU]);
1407 
1408         return 0;
1409 }
1410 
1411 static size_t ipgre_get_size(const struct net_device *dev)
1412 {
1413         return
1414                 /* IFLA_GRE_LINK */
1415                 nla_total_size(4) +
1416                 /* IFLA_GRE_IFLAGS */
1417                 nla_total_size(2) +
1418                 /* IFLA_GRE_OFLAGS */
1419                 nla_total_size(2) +
1420                 /* IFLA_GRE_IKEY */
1421                 nla_total_size(4) +
1422                 /* IFLA_GRE_OKEY */
1423                 nla_total_size(4) +
1424                 /* IFLA_GRE_LOCAL */
1425                 nla_total_size(4) +
1426                 /* IFLA_GRE_REMOTE */
1427                 nla_total_size(4) +
1428                 /* IFLA_GRE_TTL */
1429                 nla_total_size(1) +
1430                 /* IFLA_GRE_TOS */
1431                 nla_total_size(1) +
1432                 /* IFLA_GRE_PMTUDISC */
1433                 nla_total_size(1) +
1434                 /* IFLA_GRE_ENCAP_TYPE */
1435                 nla_total_size(2) +
1436                 /* IFLA_GRE_ENCAP_FLAGS */
1437                 nla_total_size(2) +
1438                 /* IFLA_GRE_ENCAP_SPORT */
1439                 nla_total_size(2) +
1440                 /* IFLA_GRE_ENCAP_DPORT */
1441                 nla_total_size(2) +
1442                 /* IFLA_GRE_COLLECT_METADATA */
1443                 nla_total_size(0) +
1444                 /* IFLA_GRE_IGNORE_DF */
1445                 nla_total_size(1) +
1446                 /* IFLA_GRE_FWMARK */
1447                 nla_total_size(4) +
1448                 /* IFLA_GRE_ERSPAN_INDEX */
1449                 nla_total_size(4) +
1450                 /* IFLA_GRE_ERSPAN_VER */
1451                 nla_total_size(1) +
1452                 /* IFLA_GRE_ERSPAN_DIR */
1453                 nla_total_size(1) +
1454                 /* IFLA_GRE_ERSPAN_HWID */
1455                 nla_total_size(2) +
1456                 0;
1457 }
1458 
1459 static int ipgre_fill_info(struct sk_buff *skb, const struct net_device *dev)
1460 {
1461         struct ip_tunnel *t = netdev_priv(dev);
1462         struct ip_tunnel_parm *p = &t->parms;
1463         __be16 o_flags = p->o_flags;
1464 
1465         if (t->erspan_ver == 1 || t->erspan_ver == 2) {
1466                 if (!t->collect_md)
1467                         o_flags |= TUNNEL_KEY;
1468 
1469                 if (nla_put_u8(skb, IFLA_GRE_ERSPAN_VER, t->erspan_ver))
1470                         goto nla_put_failure;
1471 
1472                 if (t->erspan_ver == 1) {
1473                         if (nla_put_u32(skb, IFLA_GRE_ERSPAN_INDEX, t->index))
1474                                 goto nla_put_failure;
1475                 } else {
1476                         if (nla_put_u8(skb, IFLA_GRE_ERSPAN_DIR, t->dir))
1477                                 goto nla_put_failure;
1478                         if (nla_put_u16(skb, IFLA_GRE_ERSPAN_HWID, t->hwid))
1479                                 goto nla_put_failure;
1480                 }
1481         }
1482 
1483         if (nla_put_u32(skb, IFLA_GRE_LINK, p->link) ||
1484             nla_put_be16(skb, IFLA_GRE_IFLAGS,
1485                          gre_tnl_flags_to_gre_flags(p->i_flags)) ||
1486             nla_put_be16(skb, IFLA_GRE_OFLAGS,
1487                          gre_tnl_flags_to_gre_flags(o_flags)) ||
1488             nla_put_be32(skb, IFLA_GRE_IKEY, p->i_key) ||
1489             nla_put_be32(skb, IFLA_GRE_OKEY, p->o_key) ||
1490             nla_put_in_addr(skb, IFLA_GRE_LOCAL, p->iph.saddr) ||
1491             nla_put_in_addr(skb, IFLA_GRE_REMOTE, p->iph.daddr) ||
1492             nla_put_u8(skb, IFLA_GRE_TTL, p->iph.ttl) ||
1493             nla_put_u8(skb, IFLA_GRE_TOS, p->iph.tos) ||
1494             nla_put_u8(skb, IFLA_GRE_PMTUDISC,
1495                        !!(p->iph.frag_off & htons(IP_DF))) ||
1496             nla_put_u32(skb, IFLA_GRE_FWMARK, t->fwmark))
1497                 goto nla_put_failure;
1498 
1499         if (nla_put_u16(skb, IFLA_GRE_ENCAP_TYPE,
1500                         t->encap.type) ||
1501             nla_put_be16(skb, IFLA_GRE_ENCAP_SPORT,
1502                          t->encap.sport) ||
1503             nla_put_be16(skb, IFLA_GRE_ENCAP_DPORT,
1504                          t->encap.dport) ||
1505             nla_put_u16(skb, IFLA_GRE_ENCAP_FLAGS,
1506                         t->encap.flags))
1507                 goto nla_put_failure;
1508 
1509         if (nla_put_u8(skb, IFLA_GRE_IGNORE_DF, t->ignore_df))
1510                 goto nla_put_failure;
1511 
1512         if (t->collect_md) {
1513                 if (nla_put_flag(skb, IFLA_GRE_COLLECT_METADATA))
1514                         goto nla_put_failure;
1515         }
1516 
1517         return 0;
1518 
1519 nla_put_failure:
1520         return -EMSGSIZE;
1521 }
1522 
1523 static void erspan_setup(struct net_device *dev)
1524 {
1525         struct ip_tunnel *t = netdev_priv(dev);
1526 
1527         ether_setup(dev);
1528         dev->netdev_ops = &erspan_netdev_ops;
1529         dev->priv_flags &= ~IFF_TX_SKB_SHARING;
1530         dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
1531         ip_tunnel_setup(dev, erspan_net_id);
1532         t->erspan_ver = 1;
1533 }
1534 
1535 static const struct nla_policy ipgre_policy[IFLA_GRE_MAX + 1] = {
1536         [IFLA_GRE_LINK]         = { .type = NLA_U32 },
1537         [IFLA_GRE_IFLAGS]       = { .type = NLA_U16 },
1538         [IFLA_GRE_OFLAGS]       = { .type = NLA_U16 },
1539         [IFLA_GRE_IKEY]         = { .type = NLA_U32 },
1540         [IFLA_GRE_OKEY]         = { .type = NLA_U32 },
1541         [IFLA_GRE_LOCAL]        = { .len = FIELD_SIZEOF(struct iphdr, saddr) },
1542         [IFLA_GRE_REMOTE]       = { .len = FIELD_SIZEOF(struct iphdr, daddr) },
1543         [IFLA_GRE_TTL]          = { .type = NLA_U8 },
1544         [IFLA_GRE_TOS]          = { .type = NLA_U8 },
1545         [IFLA_GRE_PMTUDISC]     = { .type = NLA_U8 },
1546         [IFLA_GRE_ENCAP_TYPE]   = { .type = NLA_U16 },
1547         [IFLA_GRE_ENCAP_FLAGS]  = { .type = NLA_U16 },
1548         [IFLA_GRE_ENCAP_SPORT]  = { .type = NLA_U16 },
1549         [IFLA_GRE_ENCAP_DPORT]  = { .type = NLA_U16 },
1550         [IFLA_GRE_COLLECT_METADATA]     = { .type = NLA_FLAG },
1551         [IFLA_GRE_IGNORE_DF]    = { .type = NLA_U8 },
1552         [IFLA_GRE_FWMARK]       = { .type = NLA_U32 },
1553         [IFLA_GRE_ERSPAN_INDEX] = { .type = NLA_U32 },
1554         [IFLA_GRE_ERSPAN_VER]   = { .type = NLA_U8 },
1555         [IFLA_GRE_ERSPAN_DIR]   = { .type = NLA_U8 },
1556         [IFLA_GRE_ERSPAN_HWID]  = { .type = NLA_U16 },
1557 };
1558 
1559 static struct rtnl_link_ops ipgre_link_ops __read_mostly = {
1560         .kind           = "gre",
1561         .maxtype        = IFLA_GRE_MAX,
1562         .policy         = ipgre_policy,
1563         .priv_size      = sizeof(struct ip_tunnel),
1564         .setup          = ipgre_tunnel_setup,
1565         .validate       = ipgre_tunnel_validate,
1566         .newlink        = ipgre_newlink,
1567         .changelink     = ipgre_changelink,
1568         .dellink        = ip_tunnel_dellink,
1569         .get_size       = ipgre_get_size,
1570         .fill_info      = ipgre_fill_info,
1571         .get_link_net   = ip_tunnel_get_link_net,
1572 };
1573 
1574 static struct rtnl_link_ops ipgre_tap_ops __read_mostly = {
1575         .kind           = "gretap",
1576         .maxtype        = IFLA_GRE_MAX,
1577         .policy         = ipgre_policy,
1578         .priv_size      = sizeof(struct ip_tunnel),
1579         .setup          = ipgre_tap_setup,
1580         .validate       = ipgre_tap_validate,
1581         .newlink        = ipgre_newlink,
1582         .changelink     = ipgre_changelink,
1583         .dellink        = ip_tunnel_dellink,
1584         .get_size       = ipgre_get_size,
1585         .fill_info      = ipgre_fill_info,
1586         .get_link_net   = ip_tunnel_get_link_net,
1587 };
1588 
1589 static struct rtnl_link_ops erspan_link_ops __read_mostly = {
1590         .kind           = "erspan",
1591         .maxtype        = IFLA_GRE_MAX,
1592         .policy         = ipgre_policy,
1593         .priv_size      = sizeof(struct ip_tunnel),
1594         .setup          = erspan_setup,
1595         .validate       = erspan_validate,
1596         .newlink        = ipgre_newlink,
1597         .changelink     = ipgre_changelink,
1598         .dellink        = ip_tunnel_dellink,
1599         .get_size       = ipgre_get_size,
1600         .fill_info      = ipgre_fill_info,
1601         .get_link_net   = ip_tunnel_get_link_net,
1602 };
1603 
1604 struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
1605                                         u8 name_assign_type)
1606 {
1607         struct nlattr *tb[IFLA_MAX + 1];
1608         struct net_device *dev;
1609         LIST_HEAD(list_kill);
1610         struct ip_tunnel *t;
1611         int err;
1612 
1613         memset(&tb, 0, sizeof(tb));
1614 
1615         dev = rtnl_create_link(net, name, name_assign_type,
1616                                &ipgre_tap_ops, tb, NULL);
1617         if (IS_ERR(dev))
1618                 return dev;
1619 
1620         /* Configure flow based GRE device. */
1621         t = netdev_priv(dev);
1622         t->collect_md = true;
1623 
1624         err = ipgre_newlink(net, dev, tb, NULL, NULL);
1625         if (err < 0) {
1626                 free_netdev(dev);
1627                 return ERR_PTR(err);
1628         }
1629 
1630         /* openvswitch users expect packet sizes to be unrestricted,
1631          * so set the largest MTU we can.
1632          */
1633         err = __ip_tunnel_change_mtu(dev, IP_MAX_MTU, false);
1634         if (err)
1635                 goto out;
1636 
1637         err = rtnl_configure_link(dev, NULL);
1638         if (err < 0)
1639                 goto out;
1640 
1641         return dev;
1642 out:
1643         ip_tunnel_dellink(dev, &list_kill);
1644         unregister_netdevice_many(&list_kill);
1645         return ERR_PTR(err);
1646 }
1647 EXPORT_SYMBOL_GPL(gretap_fb_dev_create);
1648 
1649 static int __net_init ipgre_tap_init_net(struct net *net)
1650 {
1651         return ip_tunnel_init_net(net, gre_tap_net_id, &ipgre_tap_ops, "gretap0");
1652 }
1653 
1654 static void __net_exit ipgre_tap_exit_batch_net(struct list_head *list_net)
1655 {
1656         ip_tunnel_delete_nets(list_net, gre_tap_net_id, &ipgre_tap_ops);
1657 }
1658 
1659 static struct pernet_operations ipgre_tap_net_ops = {
1660         .init = ipgre_tap_init_net,
1661         .exit_batch = ipgre_tap_exit_batch_net,
1662         .id   = &gre_tap_net_id,
1663         .size = sizeof(struct ip_tunnel_net),
1664 };
1665 
1666 static int __net_init erspan_init_net(struct net *net)
1667 {
1668         return ip_tunnel_init_net(net, erspan_net_id,
1669                                   &erspan_link_ops, "erspan0");
1670 }
1671 
1672 static void __net_exit erspan_exit_batch_net(struct list_head *net_list)
1673 {
1674         ip_tunnel_delete_nets(net_list, erspan_net_id, &erspan_link_ops);
1675 }
1676 
1677 static struct pernet_operations erspan_net_ops = {
1678         .init = erspan_init_net,
1679         .exit_batch = erspan_exit_batch_net,
1680         .id   = &erspan_net_id,
1681         .size = sizeof(struct ip_tunnel_net),
1682 };
1683 
1684 static int __init ipgre_init(void)
1685 {
1686         int err;
1687 
1688         pr_info("GRE over IPv4 tunneling driver\n");
1689 
1690         err = register_pernet_device(&ipgre_net_ops);
1691         if (err < 0)
1692                 return err;
1693 
1694         err = register_pernet_device(&ipgre_tap_net_ops);
1695         if (err < 0)
1696                 goto pnet_tap_failed;
1697 
1698         err = register_pernet_device(&erspan_net_ops);
1699         if (err < 0)
1700                 goto pnet_erspan_failed;
1701 
1702         err = gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO);
1703         if (err < 0) {
1704                 pr_info("%s: can't add protocol\n", __func__);
1705                 goto add_proto_failed;
1706         }
1707 
1708         err = rtnl_link_register(&ipgre_link_ops);
1709         if (err < 0)
1710                 goto rtnl_link_failed;
1711 
1712         err = rtnl_link_register(&ipgre_tap_ops);
1713         if (err < 0)
1714                 goto tap_ops_failed;
1715 
1716         err = rtnl_link_register(&erspan_link_ops);
1717         if (err < 0)
1718                 goto erspan_link_failed;
1719 
1720         return 0;
1721 
1722 erspan_link_failed:
1723         rtnl_link_unregister(&ipgre_tap_ops);
1724 tap_ops_failed:
1725         rtnl_link_unregister(&ipgre_link_ops);
1726 rtnl_link_failed:
1727         gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
1728 add_proto_failed:
1729         unregister_pernet_device(&erspan_net_ops);
1730 pnet_erspan_failed:
1731         unregister_pernet_device(&ipgre_tap_net_ops);
1732 pnet_tap_failed:
1733         unregister_pernet_device(&ipgre_net_ops);
1734         return err;
1735 }
1736 
1737 static void __exit ipgre_fini(void)
1738 {
1739         rtnl_link_unregister(&ipgre_tap_ops);
1740         rtnl_link_unregister(&ipgre_link_ops);
1741         rtnl_link_unregister(&erspan_link_ops);
1742         gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
1743         unregister_pernet_device(&ipgre_tap_net_ops);
1744         unregister_pernet_device(&ipgre_net_ops);
1745         unregister_pernet_device(&erspan_net_ops);
1746 }
1747 
1748 module_init(ipgre_init);
1749 module_exit(ipgre_fini);
1750 MODULE_LICENSE("GPL");
1751 MODULE_ALIAS_RTNL_LINK("gre");
1752 MODULE_ALIAS_RTNL_LINK("gretap");
1753 MODULE_ALIAS_RTNL_LINK("erspan");
1754 MODULE_ALIAS_NETDEV("gre0");
1755 MODULE_ALIAS_NETDEV("gretap0");
1756 MODULE_ALIAS_NETDEV("erspan0");
1757 

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