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Linux/net/netfilter/ipvs/ip_vs_xmit.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * ip_vs_xmit.c: various packet transmitters for IPVS
  4  *
  5  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
  6  *              Julian Anastasov <ja@ssi.bg>
  7  *
  8  * Changes:
  9  *
 10  * Description of forwarding methods:
 11  * - all transmitters are called from LOCAL_IN (remote clients) and
 12  * LOCAL_OUT (local clients) but for ICMP can be called from FORWARD
 13  * - not all connections have destination server, for example,
 14  * connections in backup server when fwmark is used
 15  * - bypass connections use daddr from packet
 16  * - we can use dst without ref while sending in RCU section, we use
 17  * ref when returning NF_ACCEPT for NAT-ed packet via loopback
 18  * LOCAL_OUT rules:
 19  * - skb->dev is NULL, skb->protocol is not set (both are set in POST_ROUTING)
 20  * - skb->pkt_type is not set yet
 21  * - the only place where we can see skb->sk != NULL
 22  */
 23 
 24 #define KMSG_COMPONENT "IPVS"
 25 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
 26 
 27 #include <linux/kernel.h>
 28 #include <linux/slab.h>
 29 #include <linux/tcp.h>                  /* for tcphdr */
 30 #include <net/ip.h>
 31 #include <net/gue.h>
 32 #include <net/gre.h>
 33 #include <net/tcp.h>                    /* for csum_tcpudp_magic */
 34 #include <net/udp.h>
 35 #include <net/icmp.h>                   /* for icmp_send */
 36 #include <net/route.h>                  /* for ip_route_output */
 37 #include <net/ipv6.h>
 38 #include <net/ip6_route.h>
 39 #include <net/ip_tunnels.h>
 40 #include <net/ip6_checksum.h>
 41 #include <net/addrconf.h>
 42 #include <linux/icmpv6.h>
 43 #include <linux/netfilter.h>
 44 #include <linux/netfilter_ipv4.h>
 45 
 46 #include <net/ip_vs.h>
 47 
 48 enum {
 49         IP_VS_RT_MODE_LOCAL     = 1, /* Allow local dest */
 50         IP_VS_RT_MODE_NON_LOCAL = 2, /* Allow non-local dest */
 51         IP_VS_RT_MODE_RDR       = 4, /* Allow redirect from remote daddr to
 52                                       * local
 53                                       */
 54         IP_VS_RT_MODE_CONNECT   = 8, /* Always bind route to saddr */
 55         IP_VS_RT_MODE_KNOWN_NH  = 16,/* Route via remote addr */
 56         IP_VS_RT_MODE_TUNNEL    = 32,/* Tunnel mode */
 57 };
 58 
 59 static inline struct ip_vs_dest_dst *ip_vs_dest_dst_alloc(void)
 60 {
 61         return kmalloc(sizeof(struct ip_vs_dest_dst), GFP_ATOMIC);
 62 }
 63 
 64 static inline void ip_vs_dest_dst_free(struct ip_vs_dest_dst *dest_dst)
 65 {
 66         kfree(dest_dst);
 67 }
 68 
 69 /*
 70  *      Destination cache to speed up outgoing route lookup
 71  */
 72 static inline void
 73 __ip_vs_dst_set(struct ip_vs_dest *dest, struct ip_vs_dest_dst *dest_dst,
 74                 struct dst_entry *dst, u32 dst_cookie)
 75 {
 76         struct ip_vs_dest_dst *old;
 77 
 78         old = rcu_dereference_protected(dest->dest_dst,
 79                                         lockdep_is_held(&dest->dst_lock));
 80 
 81         if (dest_dst) {
 82                 dest_dst->dst_cache = dst;
 83                 dest_dst->dst_cookie = dst_cookie;
 84         }
 85         rcu_assign_pointer(dest->dest_dst, dest_dst);
 86 
 87         if (old)
 88                 call_rcu(&old->rcu_head, ip_vs_dest_dst_rcu_free);
 89 }
 90 
 91 static inline struct ip_vs_dest_dst *
 92 __ip_vs_dst_check(struct ip_vs_dest *dest)
 93 {
 94         struct ip_vs_dest_dst *dest_dst = rcu_dereference(dest->dest_dst);
 95         struct dst_entry *dst;
 96 
 97         if (!dest_dst)
 98                 return NULL;
 99         dst = dest_dst->dst_cache;
100         if (dst->obsolete &&
101             dst->ops->check(dst, dest_dst->dst_cookie) == NULL)
102                 return NULL;
103         return dest_dst;
104 }
105 
106 static inline bool
107 __mtu_check_toobig_v6(const struct sk_buff *skb, u32 mtu)
108 {
109         if (IP6CB(skb)->frag_max_size) {
110                 /* frag_max_size tell us that, this packet have been
111                  * defragmented by netfilter IPv6 conntrack module.
112                  */
113                 if (IP6CB(skb)->frag_max_size > mtu)
114                         return true; /* largest fragment violate MTU */
115         }
116         else if (skb->len > mtu && !skb_is_gso(skb)) {
117                 return true; /* Packet size violate MTU size */
118         }
119         return false;
120 }
121 
122 /* Get route to daddr, update *saddr, optionally bind route to saddr */
123 static struct rtable *do_output_route4(struct net *net, __be32 daddr,
124                                        int rt_mode, __be32 *saddr)
125 {
126         struct flowi4 fl4;
127         struct rtable *rt;
128         bool loop = false;
129 
130         memset(&fl4, 0, sizeof(fl4));
131         fl4.daddr = daddr;
132         fl4.flowi4_flags = (rt_mode & IP_VS_RT_MODE_KNOWN_NH) ?
133                            FLOWI_FLAG_KNOWN_NH : 0;
134 
135 retry:
136         rt = ip_route_output_key(net, &fl4);
137         if (IS_ERR(rt)) {
138                 /* Invalid saddr ? */
139                 if (PTR_ERR(rt) == -EINVAL && *saddr &&
140                     rt_mode & IP_VS_RT_MODE_CONNECT && !loop) {
141                         *saddr = 0;
142                         flowi4_update_output(&fl4, 0, 0, daddr, 0);
143                         goto retry;
144                 }
145                 IP_VS_DBG_RL("ip_route_output error, dest: %pI4\n", &daddr);
146                 return NULL;
147         } else if (!*saddr && rt_mode & IP_VS_RT_MODE_CONNECT && fl4.saddr) {
148                 ip_rt_put(rt);
149                 *saddr = fl4.saddr;
150                 flowi4_update_output(&fl4, 0, 0, daddr, fl4.saddr);
151                 loop = true;
152                 goto retry;
153         }
154         *saddr = fl4.saddr;
155         return rt;
156 }
157 
158 #ifdef CONFIG_IP_VS_IPV6
159 static inline int __ip_vs_is_local_route6(struct rt6_info *rt)
160 {
161         return rt->dst.dev && rt->dst.dev->flags & IFF_LOOPBACK;
162 }
163 #endif
164 
165 static inline bool crosses_local_route_boundary(int skb_af, struct sk_buff *skb,
166                                                 int rt_mode,
167                                                 bool new_rt_is_local)
168 {
169         bool rt_mode_allow_local = !!(rt_mode & IP_VS_RT_MODE_LOCAL);
170         bool rt_mode_allow_non_local = !!(rt_mode & IP_VS_RT_MODE_NON_LOCAL);
171         bool rt_mode_allow_redirect = !!(rt_mode & IP_VS_RT_MODE_RDR);
172         bool source_is_loopback;
173         bool old_rt_is_local;
174 
175 #ifdef CONFIG_IP_VS_IPV6
176         if (skb_af == AF_INET6) {
177                 int addr_type = ipv6_addr_type(&ipv6_hdr(skb)->saddr);
178 
179                 source_is_loopback =
180                         (!skb->dev || skb->dev->flags & IFF_LOOPBACK) &&
181                         (addr_type & IPV6_ADDR_LOOPBACK);
182                 old_rt_is_local = __ip_vs_is_local_route6(
183                         (struct rt6_info *)skb_dst(skb));
184         } else
185 #endif
186         {
187                 source_is_loopback = ipv4_is_loopback(ip_hdr(skb)->saddr);
188                 old_rt_is_local = skb_rtable(skb)->rt_flags & RTCF_LOCAL;
189         }
190 
191         if (unlikely(new_rt_is_local)) {
192                 if (!rt_mode_allow_local)
193                         return true;
194                 if (!rt_mode_allow_redirect && !old_rt_is_local)
195                         return true;
196         } else {
197                 if (!rt_mode_allow_non_local)
198                         return true;
199                 if (source_is_loopback)
200                         return true;
201         }
202         return false;
203 }
204 
205 static inline void maybe_update_pmtu(int skb_af, struct sk_buff *skb, int mtu)
206 {
207         struct sock *sk = skb->sk;
208         struct rtable *ort = skb_rtable(skb);
209 
210         if (!skb->dev && sk && sk_fullsock(sk))
211                 ort->dst.ops->update_pmtu(&ort->dst, sk, NULL, mtu);
212 }
213 
214 static inline bool ensure_mtu_is_adequate(struct netns_ipvs *ipvs, int skb_af,
215                                           int rt_mode,
216                                           struct ip_vs_iphdr *ipvsh,
217                                           struct sk_buff *skb, int mtu)
218 {
219 #ifdef CONFIG_IP_VS_IPV6
220         if (skb_af == AF_INET6) {
221                 struct net *net = ipvs->net;
222 
223                 if (unlikely(__mtu_check_toobig_v6(skb, mtu))) {
224                         if (!skb->dev)
225                                 skb->dev = net->loopback_dev;
226                         /* only send ICMP too big on first fragment */
227                         if (!ipvsh->fragoffs && !ip_vs_iph_icmp(ipvsh))
228                                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
229                         IP_VS_DBG(1, "frag needed for %pI6c\n",
230                                   &ipv6_hdr(skb)->saddr);
231                         return false;
232                 }
233         } else
234 #endif
235         {
236                 /* If we're going to tunnel the packet and pmtu discovery
237                  * is disabled, we'll just fragment it anyway
238                  */
239                 if ((rt_mode & IP_VS_RT_MODE_TUNNEL) && !sysctl_pmtu_disc(ipvs))
240                         return true;
241 
242                 if (unlikely(ip_hdr(skb)->frag_off & htons(IP_DF) &&
243                              skb->len > mtu && !skb_is_gso(skb) &&
244                              !ip_vs_iph_icmp(ipvsh))) {
245                         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
246                                   htonl(mtu));
247                         IP_VS_DBG(1, "frag needed for %pI4\n",
248                                   &ip_hdr(skb)->saddr);
249                         return false;
250                 }
251         }
252 
253         return true;
254 }
255 
256 static inline bool decrement_ttl(struct netns_ipvs *ipvs,
257                                  int skb_af,
258                                  struct sk_buff *skb)
259 {
260         struct net *net = ipvs->net;
261 
262 #ifdef CONFIG_IP_VS_IPV6
263         if (skb_af == AF_INET6) {
264                 struct dst_entry *dst = skb_dst(skb);
265 
266                 /* check and decrement ttl */
267                 if (ipv6_hdr(skb)->hop_limit <= 1) {
268                         struct inet6_dev *idev = __in6_dev_get_safely(skb->dev);
269 
270                         /* Force OUTPUT device used as source address */
271                         skb->dev = dst->dev;
272                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
273                                     ICMPV6_EXC_HOPLIMIT, 0);
274                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
275 
276                         return false;
277                 }
278 
279                 /* don't propagate ttl change to cloned packets */
280                 if (skb_ensure_writable(skb, sizeof(struct ipv6hdr)))
281                         return false;
282 
283                 ipv6_hdr(skb)->hop_limit--;
284         } else
285 #endif
286         {
287                 if (ip_hdr(skb)->ttl <= 1) {
288                         /* Tell the sender its packet died... */
289                         __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
290                         icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0);
291                         return false;
292                 }
293 
294                 /* don't propagate ttl change to cloned packets */
295                 if (skb_ensure_writable(skb, sizeof(struct iphdr)))
296                         return false;
297 
298                 /* Decrease ttl */
299                 ip_decrease_ttl(ip_hdr(skb));
300         }
301 
302         return true;
303 }
304 
305 /* Get route to destination or remote server */
306 static int
307 __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
308                    struct ip_vs_dest *dest,
309                    __be32 daddr, int rt_mode, __be32 *ret_saddr,
310                    struct ip_vs_iphdr *ipvsh)
311 {
312         struct net *net = ipvs->net;
313         struct ip_vs_dest_dst *dest_dst;
314         struct rtable *rt;                      /* Route to the other host */
315         int mtu;
316         int local, noref = 1;
317 
318         if (dest) {
319                 dest_dst = __ip_vs_dst_check(dest);
320                 if (likely(dest_dst))
321                         rt = (struct rtable *) dest_dst->dst_cache;
322                 else {
323                         dest_dst = ip_vs_dest_dst_alloc();
324                         spin_lock_bh(&dest->dst_lock);
325                         if (!dest_dst) {
326                                 __ip_vs_dst_set(dest, NULL, NULL, 0);
327                                 spin_unlock_bh(&dest->dst_lock);
328                                 goto err_unreach;
329                         }
330                         rt = do_output_route4(net, dest->addr.ip, rt_mode,
331                                               &dest_dst->dst_saddr.ip);
332                         if (!rt) {
333                                 __ip_vs_dst_set(dest, NULL, NULL, 0);
334                                 spin_unlock_bh(&dest->dst_lock);
335                                 ip_vs_dest_dst_free(dest_dst);
336                                 goto err_unreach;
337                         }
338                         __ip_vs_dst_set(dest, dest_dst, &rt->dst, 0);
339                         spin_unlock_bh(&dest->dst_lock);
340                         IP_VS_DBG(10, "new dst %pI4, src %pI4, refcnt=%d\n",
341                                   &dest->addr.ip, &dest_dst->dst_saddr.ip,
342                                   atomic_read(&rt->dst.__refcnt));
343                 }
344                 if (ret_saddr)
345                         *ret_saddr = dest_dst->dst_saddr.ip;
346         } else {
347                 __be32 saddr = htonl(INADDR_ANY);
348 
349                 noref = 0;
350 
351                 /* For such unconfigured boxes avoid many route lookups
352                  * for performance reasons because we do not remember saddr
353                  */
354                 rt_mode &= ~IP_VS_RT_MODE_CONNECT;
355                 rt = do_output_route4(net, daddr, rt_mode, &saddr);
356                 if (!rt)
357                         goto err_unreach;
358                 if (ret_saddr)
359                         *ret_saddr = saddr;
360         }
361 
362         local = (rt->rt_flags & RTCF_LOCAL) ? 1 : 0;
363         if (unlikely(crosses_local_route_boundary(skb_af, skb, rt_mode,
364                                                   local))) {
365                 IP_VS_DBG_RL("We are crossing local and non-local addresses"
366                              " daddr=%pI4\n", &daddr);
367                 goto err_put;
368         }
369 
370         if (unlikely(local)) {
371                 /* skb to local stack, preserve old route */
372                 if (!noref)
373                         ip_rt_put(rt);
374                 return local;
375         }
376 
377         if (!decrement_ttl(ipvs, skb_af, skb))
378                 goto err_put;
379 
380         if (likely(!(rt_mode & IP_VS_RT_MODE_TUNNEL))) {
381                 mtu = dst_mtu(&rt->dst);
382         } else {
383                 mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
384                 if (!dest)
385                         goto err_put;
386                 if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
387                         mtu -= sizeof(struct udphdr) + sizeof(struct guehdr);
388                         if ((dest->tun_flags &
389                              IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
390                             skb->ip_summed == CHECKSUM_PARTIAL)
391                                 mtu -= GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
392                 } else if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
393                         __be16 tflags = 0;
394 
395                         if (dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
396                                 tflags |= TUNNEL_CSUM;
397                         mtu -= gre_calc_hlen(tflags);
398                 }
399                 if (mtu < 68) {
400                         IP_VS_DBG_RL("%s(): mtu less than 68\n", __func__);
401                         goto err_put;
402                 }
403                 maybe_update_pmtu(skb_af, skb, mtu);
404         }
405 
406         if (!ensure_mtu_is_adequate(ipvs, skb_af, rt_mode, ipvsh, skb, mtu))
407                 goto err_put;
408 
409         skb_dst_drop(skb);
410         if (noref) {
411                 if (!local)
412                         skb_dst_set_noref(skb, &rt->dst);
413                 else
414                         skb_dst_set(skb, dst_clone(&rt->dst));
415         } else
416                 skb_dst_set(skb, &rt->dst);
417 
418         return local;
419 
420 err_put:
421         if (!noref)
422                 ip_rt_put(rt);
423         return -1;
424 
425 err_unreach:
426         dst_link_failure(skb);
427         return -1;
428 }
429 
430 #ifdef CONFIG_IP_VS_IPV6
431 static struct dst_entry *
432 __ip_vs_route_output_v6(struct net *net, struct in6_addr *daddr,
433                         struct in6_addr *ret_saddr, int do_xfrm, int rt_mode)
434 {
435         struct dst_entry *dst;
436         struct flowi6 fl6 = {
437                 .daddr = *daddr,
438         };
439 
440         if (rt_mode & IP_VS_RT_MODE_KNOWN_NH)
441                 fl6.flowi6_flags = FLOWI_FLAG_KNOWN_NH;
442 
443         dst = ip6_route_output(net, NULL, &fl6);
444         if (dst->error)
445                 goto out_err;
446         if (!ret_saddr)
447                 return dst;
448         if (ipv6_addr_any(&fl6.saddr) &&
449             ipv6_dev_get_saddr(net, ip6_dst_idev(dst)->dev,
450                                &fl6.daddr, 0, &fl6.saddr) < 0)
451                 goto out_err;
452         if (do_xfrm) {
453                 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
454                 if (IS_ERR(dst)) {
455                         dst = NULL;
456                         goto out_err;
457                 }
458         }
459         *ret_saddr = fl6.saddr;
460         return dst;
461 
462 out_err:
463         dst_release(dst);
464         IP_VS_DBG_RL("ip6_route_output error, dest: %pI6\n", daddr);
465         return NULL;
466 }
467 
468 /*
469  * Get route to destination or remote server
470  */
471 static int
472 __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
473                       struct ip_vs_dest *dest,
474                       struct in6_addr *daddr, struct in6_addr *ret_saddr,
475                       struct ip_vs_iphdr *ipvsh, int do_xfrm, int rt_mode)
476 {
477         struct net *net = ipvs->net;
478         struct ip_vs_dest_dst *dest_dst;
479         struct rt6_info *rt;                    /* Route to the other host */
480         struct dst_entry *dst;
481         int mtu;
482         int local, noref = 1;
483 
484         if (dest) {
485                 dest_dst = __ip_vs_dst_check(dest);
486                 if (likely(dest_dst))
487                         rt = (struct rt6_info *) dest_dst->dst_cache;
488                 else {
489                         u32 cookie;
490 
491                         dest_dst = ip_vs_dest_dst_alloc();
492                         spin_lock_bh(&dest->dst_lock);
493                         if (!dest_dst) {
494                                 __ip_vs_dst_set(dest, NULL, NULL, 0);
495                                 spin_unlock_bh(&dest->dst_lock);
496                                 goto err_unreach;
497                         }
498                         dst = __ip_vs_route_output_v6(net, &dest->addr.in6,
499                                                       &dest_dst->dst_saddr.in6,
500                                                       do_xfrm, rt_mode);
501                         if (!dst) {
502                                 __ip_vs_dst_set(dest, NULL, NULL, 0);
503                                 spin_unlock_bh(&dest->dst_lock);
504                                 ip_vs_dest_dst_free(dest_dst);
505                                 goto err_unreach;
506                         }
507                         rt = (struct rt6_info *) dst;
508                         cookie = rt6_get_cookie(rt);
509                         __ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie);
510                         spin_unlock_bh(&dest->dst_lock);
511                         IP_VS_DBG(10, "new dst %pI6, src %pI6, refcnt=%d\n",
512                                   &dest->addr.in6, &dest_dst->dst_saddr.in6,
513                                   atomic_read(&rt->dst.__refcnt));
514                 }
515                 if (ret_saddr)
516                         *ret_saddr = dest_dst->dst_saddr.in6;
517         } else {
518                 noref = 0;
519                 dst = __ip_vs_route_output_v6(net, daddr, ret_saddr, do_xfrm,
520                                               rt_mode);
521                 if (!dst)
522                         goto err_unreach;
523                 rt = (struct rt6_info *) dst;
524         }
525 
526         local = __ip_vs_is_local_route6(rt);
527 
528         if (unlikely(crosses_local_route_boundary(skb_af, skb, rt_mode,
529                                                   local))) {
530                 IP_VS_DBG_RL("We are crossing local and non-local addresses"
531                              " daddr=%pI6\n", daddr);
532                 goto err_put;
533         }
534 
535         if (unlikely(local)) {
536                 /* skb to local stack, preserve old route */
537                 if (!noref)
538                         dst_release(&rt->dst);
539                 return local;
540         }
541 
542         if (!decrement_ttl(ipvs, skb_af, skb))
543                 goto err_put;
544 
545         /* MTU checking */
546         if (likely(!(rt_mode & IP_VS_RT_MODE_TUNNEL)))
547                 mtu = dst_mtu(&rt->dst);
548         else {
549                 mtu = dst_mtu(&rt->dst) - sizeof(struct ipv6hdr);
550                 if (!dest)
551                         goto err_put;
552                 if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
553                         mtu -= sizeof(struct udphdr) + sizeof(struct guehdr);
554                         if ((dest->tun_flags &
555                              IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
556                             skb->ip_summed == CHECKSUM_PARTIAL)
557                                 mtu -= GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
558                 } else if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
559                         __be16 tflags = 0;
560 
561                         if (dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
562                                 tflags |= TUNNEL_CSUM;
563                         mtu -= gre_calc_hlen(tflags);
564                 }
565                 if (mtu < IPV6_MIN_MTU) {
566                         IP_VS_DBG_RL("%s(): mtu less than %d\n", __func__,
567                                      IPV6_MIN_MTU);
568                         goto err_put;
569                 }
570                 maybe_update_pmtu(skb_af, skb, mtu);
571         }
572 
573         if (!ensure_mtu_is_adequate(ipvs, skb_af, rt_mode, ipvsh, skb, mtu))
574                 goto err_put;
575 
576         skb_dst_drop(skb);
577         if (noref) {
578                 if (!local)
579                         skb_dst_set_noref(skb, &rt->dst);
580                 else
581                         skb_dst_set(skb, dst_clone(&rt->dst));
582         } else
583                 skb_dst_set(skb, &rt->dst);
584 
585         return local;
586 
587 err_put:
588         if (!noref)
589                 dst_release(&rt->dst);
590         return -1;
591 
592 err_unreach:
593         /* The ip6_link_failure function requires the dev field to be set
594          * in order to get the net (further for the sake of fwmark
595          * reflection).
596          */
597         if (!skb->dev)
598                 skb->dev = skb_dst(skb)->dev;
599 
600         dst_link_failure(skb);
601         return -1;
602 }
603 #endif
604 
605 
606 /* return NF_ACCEPT to allow forwarding or other NF_xxx on error */
607 static inline int ip_vs_tunnel_xmit_prepare(struct sk_buff *skb,
608                                             struct ip_vs_conn *cp)
609 {
610         int ret = NF_ACCEPT;
611 
612         skb->ipvs_property = 1;
613         if (unlikely(cp->flags & IP_VS_CONN_F_NFCT))
614                 ret = ip_vs_confirm_conntrack(skb);
615         if (ret == NF_ACCEPT) {
616                 nf_reset(skb);
617                 skb_forward_csum(skb);
618         }
619         return ret;
620 }
621 
622 /* In the event of a remote destination, it's possible that we would have
623  * matches against an old socket (particularly a TIME-WAIT socket). This
624  * causes havoc down the line (ip_local_out et. al. expect regular sockets
625  * and invalid memory accesses will happen) so simply drop the association
626  * in this case.
627 */
628 static inline void ip_vs_drop_early_demux_sk(struct sk_buff *skb)
629 {
630         /* If dev is set, the packet came from the LOCAL_IN callback and
631          * not from a local TCP socket.
632          */
633         if (skb->dev)
634                 skb_orphan(skb);
635 }
636 
637 /* return NF_STOLEN (sent) or NF_ACCEPT if local=1 (not sent) */
638 static inline int ip_vs_nat_send_or_cont(int pf, struct sk_buff *skb,
639                                          struct ip_vs_conn *cp, int local)
640 {
641         int ret = NF_STOLEN;
642 
643         skb->ipvs_property = 1;
644         if (likely(!(cp->flags & IP_VS_CONN_F_NFCT)))
645                 ip_vs_notrack(skb);
646         else
647                 ip_vs_update_conntrack(skb, cp, 1);
648 
649         /* Remove the early_demux association unless it's bound for the
650          * exact same port and address on this host after translation.
651          */
652         if (!local || cp->vport != cp->dport ||
653             !ip_vs_addr_equal(cp->af, &cp->vaddr, &cp->daddr))
654                 ip_vs_drop_early_demux_sk(skb);
655 
656         if (!local) {
657                 skb_forward_csum(skb);
658                 NF_HOOK(pf, NF_INET_LOCAL_OUT, cp->ipvs->net, NULL, skb,
659                         NULL, skb_dst(skb)->dev, dst_output);
660         } else
661                 ret = NF_ACCEPT;
662 
663         return ret;
664 }
665 
666 /* return NF_STOLEN (sent) or NF_ACCEPT if local=1 (not sent) */
667 static inline int ip_vs_send_or_cont(int pf, struct sk_buff *skb,
668                                      struct ip_vs_conn *cp, int local)
669 {
670         int ret = NF_STOLEN;
671 
672         skb->ipvs_property = 1;
673         if (likely(!(cp->flags & IP_VS_CONN_F_NFCT)))
674                 ip_vs_notrack(skb);
675         if (!local) {
676                 ip_vs_drop_early_demux_sk(skb);
677                 skb_forward_csum(skb);
678                 NF_HOOK(pf, NF_INET_LOCAL_OUT, cp->ipvs->net, NULL, skb,
679                         NULL, skb_dst(skb)->dev, dst_output);
680         } else
681                 ret = NF_ACCEPT;
682         return ret;
683 }
684 
685 
686 /*
687  *      NULL transmitter (do nothing except return NF_ACCEPT)
688  */
689 int
690 ip_vs_null_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
691                 struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
692 {
693         /* we do not touch skb and do not need pskb ptr */
694         return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1);
695 }
696 
697 
698 /*
699  *      Bypass transmitter
700  *      Let packets bypass the destination when the destination is not
701  *      available, it may be only used in transparent cache cluster.
702  */
703 int
704 ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
705                   struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
706 {
707         struct iphdr  *iph = ip_hdr(skb);
708 
709         EnterFunction(10);
710 
711         if (__ip_vs_get_out_rt(cp->ipvs, cp->af, skb, NULL, iph->daddr,
712                                IP_VS_RT_MODE_NON_LOCAL, NULL, ipvsh) < 0)
713                 goto tx_error;
714 
715         ip_send_check(iph);
716 
717         /* Another hack: avoid icmp_send in ip_fragment */
718         skb->ignore_df = 1;
719 
720         ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 0);
721 
722         LeaveFunction(10);
723         return NF_STOLEN;
724 
725  tx_error:
726         kfree_skb(skb);
727         LeaveFunction(10);
728         return NF_STOLEN;
729 }
730 
731 #ifdef CONFIG_IP_VS_IPV6
732 int
733 ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
734                      struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
735 {
736         struct ipv6hdr *iph = ipv6_hdr(skb);
737 
738         EnterFunction(10);
739 
740         if (__ip_vs_get_out_rt_v6(cp->ipvs, cp->af, skb, NULL,
741                                   &iph->daddr, NULL,
742                                   ipvsh, 0, IP_VS_RT_MODE_NON_LOCAL) < 0)
743                 goto tx_error;
744 
745         /* Another hack: avoid icmp_send in ip_fragment */
746         skb->ignore_df = 1;
747 
748         ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 0);
749 
750         LeaveFunction(10);
751         return NF_STOLEN;
752 
753  tx_error:
754         kfree_skb(skb);
755         LeaveFunction(10);
756         return NF_STOLEN;
757 }
758 #endif
759 
760 /*
761  *      NAT transmitter (only for outside-to-inside nat forwarding)
762  *      Not used for related ICMP
763  */
764 int
765 ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
766                struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
767 {
768         struct rtable *rt;              /* Route to the other host */
769         int local, rc, was_input;
770 
771         EnterFunction(10);
772 
773         /* check if it is a connection of no-client-port */
774         if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT)) {
775                 __be16 _pt, *p;
776 
777                 p = skb_header_pointer(skb, ipvsh->len, sizeof(_pt), &_pt);
778                 if (p == NULL)
779                         goto tx_error;
780                 ip_vs_conn_fill_cport(cp, *p);
781                 IP_VS_DBG(10, "filled cport=%d\n", ntohs(*p));
782         }
783 
784         was_input = rt_is_input_route(skb_rtable(skb));
785         local = __ip_vs_get_out_rt(cp->ipvs, cp->af, skb, cp->dest, cp->daddr.ip,
786                                    IP_VS_RT_MODE_LOCAL |
787                                    IP_VS_RT_MODE_NON_LOCAL |
788                                    IP_VS_RT_MODE_RDR, NULL, ipvsh);
789         if (local < 0)
790                 goto tx_error;
791         rt = skb_rtable(skb);
792         /*
793          * Avoid duplicate tuple in reply direction for NAT traffic
794          * to local address when connection is sync-ed
795          */
796 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
797         if (cp->flags & IP_VS_CONN_F_SYNC && local) {
798                 enum ip_conntrack_info ctinfo;
799                 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
800 
801                 if (ct) {
802                         IP_VS_DBG_RL_PKT(10, AF_INET, pp, skb, ipvsh->off,
803                                          "ip_vs_nat_xmit(): "
804                                          "stopping DNAT to local address");
805                         goto tx_error;
806                 }
807         }
808 #endif
809 
810         /* From world but DNAT to loopback address? */
811         if (local && ipv4_is_loopback(cp->daddr.ip) && was_input) {
812                 IP_VS_DBG_RL_PKT(1, AF_INET, pp, skb, ipvsh->off,
813                                  "ip_vs_nat_xmit(): stopping DNAT to loopback "
814                                  "address");
815                 goto tx_error;
816         }
817 
818         /* copy-on-write the packet before mangling it */
819         if (skb_ensure_writable(skb, sizeof(struct iphdr)))
820                 goto tx_error;
821 
822         if (skb_cow(skb, rt->dst.dev->hard_header_len))
823                 goto tx_error;
824 
825         /* mangle the packet */
826         if (pp->dnat_handler && !pp->dnat_handler(skb, pp, cp, ipvsh))
827                 goto tx_error;
828         ip_hdr(skb)->daddr = cp->daddr.ip;
829         ip_send_check(ip_hdr(skb));
830 
831         IP_VS_DBG_PKT(10, AF_INET, pp, skb, ipvsh->off, "After DNAT");
832 
833         /* FIXME: when application helper enlarges the packet and the length
834            is larger than the MTU of outgoing device, there will be still
835            MTU problem. */
836 
837         /* Another hack: avoid icmp_send in ip_fragment */
838         skb->ignore_df = 1;
839 
840         rc = ip_vs_nat_send_or_cont(NFPROTO_IPV4, skb, cp, local);
841 
842         LeaveFunction(10);
843         return rc;
844 
845   tx_error:
846         kfree_skb(skb);
847         LeaveFunction(10);
848         return NF_STOLEN;
849 }
850 
851 #ifdef CONFIG_IP_VS_IPV6
852 int
853 ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
854                   struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
855 {
856         struct rt6_info *rt;            /* Route to the other host */
857         int local, rc;
858 
859         EnterFunction(10);
860 
861         /* check if it is a connection of no-client-port */
862         if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT && !ipvsh->fragoffs)) {
863                 __be16 _pt, *p;
864                 p = skb_header_pointer(skb, ipvsh->len, sizeof(_pt), &_pt);
865                 if (p == NULL)
866                         goto tx_error;
867                 ip_vs_conn_fill_cport(cp, *p);
868                 IP_VS_DBG(10, "filled cport=%d\n", ntohs(*p));
869         }
870 
871         local = __ip_vs_get_out_rt_v6(cp->ipvs, cp->af, skb, cp->dest,
872                                       &cp->daddr.in6,
873                                       NULL, ipvsh, 0,
874                                       IP_VS_RT_MODE_LOCAL |
875                                       IP_VS_RT_MODE_NON_LOCAL |
876                                       IP_VS_RT_MODE_RDR);
877         if (local < 0)
878                 goto tx_error;
879         rt = (struct rt6_info *) skb_dst(skb);
880         /*
881          * Avoid duplicate tuple in reply direction for NAT traffic
882          * to local address when connection is sync-ed
883          */
884 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
885         if (cp->flags & IP_VS_CONN_F_SYNC && local) {
886                 enum ip_conntrack_info ctinfo;
887                 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
888 
889                 if (ct) {
890                         IP_VS_DBG_RL_PKT(10, AF_INET6, pp, skb, ipvsh->off,
891                                          "ip_vs_nat_xmit_v6(): "
892                                          "stopping DNAT to local address");
893                         goto tx_error;
894                 }
895         }
896 #endif
897 
898         /* From world but DNAT to loopback address? */
899         if (local && skb->dev && !(skb->dev->flags & IFF_LOOPBACK) &&
900             ipv6_addr_type(&cp->daddr.in6) & IPV6_ADDR_LOOPBACK) {
901                 IP_VS_DBG_RL_PKT(1, AF_INET6, pp, skb, ipvsh->off,
902                                  "ip_vs_nat_xmit_v6(): "
903                                  "stopping DNAT to loopback address");
904                 goto tx_error;
905         }
906 
907         /* copy-on-write the packet before mangling it */
908         if (skb_ensure_writable(skb, sizeof(struct ipv6hdr)))
909                 goto tx_error;
910 
911         if (skb_cow(skb, rt->dst.dev->hard_header_len))
912                 goto tx_error;
913 
914         /* mangle the packet */
915         if (pp->dnat_handler && !pp->dnat_handler(skb, pp, cp, ipvsh))
916                 goto tx_error;
917         ipv6_hdr(skb)->daddr = cp->daddr.in6;
918 
919         IP_VS_DBG_PKT(10, AF_INET6, pp, skb, ipvsh->off, "After DNAT");
920 
921         /* FIXME: when application helper enlarges the packet and the length
922            is larger than the MTU of outgoing device, there will be still
923            MTU problem. */
924 
925         /* Another hack: avoid icmp_send in ip_fragment */
926         skb->ignore_df = 1;
927 
928         rc = ip_vs_nat_send_or_cont(NFPROTO_IPV6, skb, cp, local);
929 
930         LeaveFunction(10);
931         return rc;
932 
933 tx_error:
934         LeaveFunction(10);
935         kfree_skb(skb);
936         return NF_STOLEN;
937 }
938 #endif
939 
940 /* When forwarding a packet, we must ensure that we've got enough headroom
941  * for the encapsulation packet in the skb.  This also gives us an
942  * opportunity to figure out what the payload_len, dsfield, ttl, and df
943  * values should be, so that we won't need to look at the old ip header
944  * again
945  */
946 static struct sk_buff *
947 ip_vs_prepare_tunneled_skb(struct sk_buff *skb, int skb_af,
948                            unsigned int max_headroom, __u8 *next_protocol,
949                            __u32 *payload_len, __u8 *dsfield, __u8 *ttl,
950                            __be16 *df)
951 {
952         struct sk_buff *new_skb = NULL;
953         struct iphdr *old_iph = NULL;
954         __u8 old_dsfield;
955 #ifdef CONFIG_IP_VS_IPV6
956         struct ipv6hdr *old_ipv6h = NULL;
957 #endif
958 
959         ip_vs_drop_early_demux_sk(skb);
960 
961         if (skb_headroom(skb) < max_headroom || skb_cloned(skb)) {
962                 new_skb = skb_realloc_headroom(skb, max_headroom);
963                 if (!new_skb)
964                         goto error;
965                 if (skb->sk)
966                         skb_set_owner_w(new_skb, skb->sk);
967                 consume_skb(skb);
968                 skb = new_skb;
969         }
970 
971 #ifdef CONFIG_IP_VS_IPV6
972         if (skb_af == AF_INET6) {
973                 old_ipv6h = ipv6_hdr(skb);
974                 *next_protocol = IPPROTO_IPV6;
975                 if (payload_len)
976                         *payload_len =
977                                 ntohs(old_ipv6h->payload_len) +
978                                 sizeof(*old_ipv6h);
979                 old_dsfield = ipv6_get_dsfield(old_ipv6h);
980                 *ttl = old_ipv6h->hop_limit;
981                 if (df)
982                         *df = 0;
983         } else
984 #endif
985         {
986                 old_iph = ip_hdr(skb);
987                 /* Copy DF, reset fragment offset and MF */
988                 if (df)
989                         *df = (old_iph->frag_off & htons(IP_DF));
990                 *next_protocol = IPPROTO_IPIP;
991 
992                 /* fix old IP header checksum */
993                 ip_send_check(old_iph);
994                 old_dsfield = ipv4_get_dsfield(old_iph);
995                 *ttl = old_iph->ttl;
996                 if (payload_len)
997                         *payload_len = ntohs(old_iph->tot_len);
998         }
999 
1000         /* Implement full-functionality option for ECN encapsulation */
1001         *dsfield = INET_ECN_encapsulate(old_dsfield, old_dsfield);
1002 
1003         return skb;
1004 error:
1005         kfree_skb(skb);
1006         return ERR_PTR(-ENOMEM);
1007 }
1008 
1009 static inline int __tun_gso_type_mask(int encaps_af, int orig_af)
1010 {
1011         switch (encaps_af) {
1012         case AF_INET:
1013                 return SKB_GSO_IPXIP4;
1014         case AF_INET6:
1015                 return SKB_GSO_IPXIP6;
1016         default:
1017                 return 0;
1018         }
1019 }
1020 
1021 static int
1022 ipvs_gue_encap(struct net *net, struct sk_buff *skb,
1023                struct ip_vs_conn *cp, __u8 *next_protocol)
1024 {
1025         __be16 dport;
1026         __be16 sport = udp_flow_src_port(net, skb, 0, 0, false);
1027         struct udphdr  *udph;   /* Our new UDP header */
1028         struct guehdr  *gueh;   /* Our new GUE header */
1029         size_t hdrlen, optlen = 0;
1030         void *data;
1031         bool need_priv = false;
1032 
1033         if ((cp->dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
1034             skb->ip_summed == CHECKSUM_PARTIAL) {
1035                 optlen += GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
1036                 need_priv = true;
1037         }
1038 
1039         hdrlen = sizeof(struct guehdr) + optlen;
1040 
1041         skb_push(skb, hdrlen);
1042 
1043         gueh = (struct guehdr *)skb->data;
1044 
1045         gueh->control = 0;
1046         gueh->version = 0;
1047         gueh->hlen = optlen >> 2;
1048         gueh->flags = 0;
1049         gueh->proto_ctype = *next_protocol;
1050 
1051         data = &gueh[1];
1052 
1053         if (need_priv) {
1054                 __be32 *flags = data;
1055                 u16 csum_start = skb_checksum_start_offset(skb);
1056                 __be16 *pd;
1057 
1058                 gueh->flags |= GUE_FLAG_PRIV;
1059                 *flags = 0;
1060                 data += GUE_LEN_PRIV;
1061 
1062                 if (csum_start < hdrlen)
1063                         return -EINVAL;
1064 
1065                 csum_start -= hdrlen;
1066                 pd = data;
1067                 pd[0] = htons(csum_start);
1068                 pd[1] = htons(csum_start + skb->csum_offset);
1069 
1070                 if (!skb_is_gso(skb)) {
1071                         skb->ip_summed = CHECKSUM_NONE;
1072                         skb->encapsulation = 0;
1073                 }
1074 
1075                 *flags |= GUE_PFLAG_REMCSUM;
1076                 data += GUE_PLEN_REMCSUM;
1077         }
1078 
1079         skb_push(skb, sizeof(struct udphdr));
1080         skb_reset_transport_header(skb);
1081 
1082         udph = udp_hdr(skb);
1083 
1084         dport = cp->dest->tun_port;
1085         udph->dest = dport;
1086         udph->source = sport;
1087         udph->len = htons(skb->len);
1088         udph->check = 0;
1089 
1090         *next_protocol = IPPROTO_UDP;
1091 
1092         return 0;
1093 }
1094 
1095 static void
1096 ipvs_gre_encap(struct net *net, struct sk_buff *skb,
1097                struct ip_vs_conn *cp, __u8 *next_protocol)
1098 {
1099         __be16 proto = *next_protocol == IPPROTO_IPIP ?
1100                                 htons(ETH_P_IP) : htons(ETH_P_IPV6);
1101         __be16 tflags = 0;
1102         size_t hdrlen;
1103 
1104         if (cp->dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
1105                 tflags |= TUNNEL_CSUM;
1106 
1107         hdrlen = gre_calc_hlen(tflags);
1108         gre_build_header(skb, hdrlen, tflags, proto, 0, 0);
1109 
1110         *next_protocol = IPPROTO_GRE;
1111 }
1112 
1113 /*
1114  *   IP Tunneling transmitter
1115  *
1116  *   This function encapsulates the packet in a new IP packet, its
1117  *   destination will be set to cp->daddr. Most code of this function
1118  *   is taken from ipip.c.
1119  *
1120  *   It is used in VS/TUN cluster. The load balancer selects a real
1121  *   server from a cluster based on a scheduling algorithm,
1122  *   encapsulates the request packet and forwards it to the selected
1123  *   server. For example, all real servers are configured with
1124  *   "ifconfig tunl0 <Virtual IP Address> up". When the server receives
1125  *   the encapsulated packet, it will decapsulate the packet, processe
1126  *   the request and return the response packets directly to the client
1127  *   without passing the load balancer. This can greatly increase the
1128  *   scalability of virtual server.
1129  *
1130  *   Used for ANY protocol
1131  */
1132 int
1133 ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
1134                   struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
1135 {
1136         struct netns_ipvs *ipvs = cp->ipvs;
1137         struct net *net = ipvs->net;
1138         struct rtable *rt;                      /* Route to the other host */
1139         __be32 saddr;                           /* Source for tunnel */
1140         struct net_device *tdev;                /* Device to other host */
1141         __u8 next_protocol = 0;
1142         __u8 dsfield = 0;
1143         __u8 ttl = 0;
1144         __be16 df = 0;
1145         __be16 *dfp = NULL;
1146         struct iphdr  *iph;                     /* Our new IP header */
1147         unsigned int max_headroom;              /* The extra header space needed */
1148         int ret, local;
1149         int tun_type, gso_type;
1150         int tun_flags;
1151 
1152         EnterFunction(10);
1153 
1154         local = __ip_vs_get_out_rt(ipvs, cp->af, skb, cp->dest, cp->daddr.ip,
1155                                    IP_VS_RT_MODE_LOCAL |
1156                                    IP_VS_RT_MODE_NON_LOCAL |
1157                                    IP_VS_RT_MODE_CONNECT |
1158                                    IP_VS_RT_MODE_TUNNEL, &saddr, ipvsh);
1159         if (local < 0)
1160                 goto tx_error;
1161         if (local)
1162                 return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1);
1163 
1164         rt = skb_rtable(skb);
1165         tdev = rt->dst.dev;
1166 
1167         /*
1168          * Okay, now see if we can stuff it in the buffer as-is.
1169          */
1170         max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct iphdr);
1171 
1172         tun_type = cp->dest->tun_type;
1173         tun_flags = cp->dest->tun_flags;
1174 
1175         if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
1176                 size_t gue_hdrlen, gue_optlen = 0;
1177 
1178                 if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
1179                     skb->ip_summed == CHECKSUM_PARTIAL) {
1180                         gue_optlen += GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
1181                 }
1182                 gue_hdrlen = sizeof(struct guehdr) + gue_optlen;
1183 
1184                 max_headroom += sizeof(struct udphdr) + gue_hdrlen;
1185         } else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
1186                 size_t gre_hdrlen;
1187                 __be16 tflags = 0;
1188 
1189                 if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
1190                         tflags |= TUNNEL_CSUM;
1191                 gre_hdrlen = gre_calc_hlen(tflags);
1192 
1193                 max_headroom += gre_hdrlen;
1194         }
1195 
1196         /* We only care about the df field if sysctl_pmtu_disc(ipvs) is set */
1197         dfp = sysctl_pmtu_disc(ipvs) ? &df : NULL;
1198         skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom,
1199                                          &next_protocol, NULL, &dsfield,
1200                                          &ttl, dfp);
1201         if (IS_ERR(skb))
1202                 goto tx_error;
1203 
1204         gso_type = __tun_gso_type_mask(AF_INET, cp->af);
1205         if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
1206                 if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM) ||
1207                     (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM))
1208                         gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
1209                 else
1210                         gso_type |= SKB_GSO_UDP_TUNNEL;
1211                 if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
1212                     skb->ip_summed == CHECKSUM_PARTIAL) {
1213                         gso_type |= SKB_GSO_TUNNEL_REMCSUM;
1214                 }
1215         } else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
1216                 if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
1217                         gso_type |= SKB_GSO_GRE_CSUM;
1218                 else
1219                         gso_type |= SKB_GSO_GRE;
1220         }
1221 
1222         if (iptunnel_handle_offloads(skb, gso_type))
1223                 goto tx_error;
1224 
1225         skb->transport_header = skb->network_header;
1226 
1227         skb_set_inner_ipproto(skb, next_protocol);
1228 
1229         if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
1230                 bool check = false;
1231 
1232                 if (ipvs_gue_encap(net, skb, cp, &next_protocol))
1233                         goto tx_error;
1234 
1235                 if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM) ||
1236                     (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM))
1237                         check = true;
1238 
1239                 udp_set_csum(!check, skb, saddr, cp->daddr.ip, skb->len);
1240         } else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE)
1241                 ipvs_gre_encap(net, skb, cp, &next_protocol);
1242 
1243         skb_push(skb, sizeof(struct iphdr));
1244         skb_reset_network_header(skb);
1245         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1246 
1247         /*
1248          *      Push down and install the IPIP header.
1249          */
1250         iph                     =       ip_hdr(skb);
1251         iph->version            =       4;
1252         iph->ihl                =       sizeof(struct iphdr)>>2;
1253         iph->frag_off           =       df;
1254         iph->protocol           =       next_protocol;
1255         iph->tos                =       dsfield;
1256         iph->daddr              =       cp->daddr.ip;
1257         iph->saddr              =       saddr;
1258         iph->ttl                =       ttl;
1259         ip_select_ident(net, skb, NULL);
1260 
1261         /* Another hack: avoid icmp_send in ip_fragment */
1262         skb->ignore_df = 1;
1263 
1264         ret = ip_vs_tunnel_xmit_prepare(skb, cp);
1265         if (ret == NF_ACCEPT)
1266                 ip_local_out(net, skb->sk, skb);
1267         else if (ret == NF_DROP)
1268                 kfree_skb(skb);
1269 
1270         LeaveFunction(10);
1271 
1272         return NF_STOLEN;
1273 
1274   tx_error:
1275         if (!IS_ERR(skb))
1276                 kfree_skb(skb);
1277         LeaveFunction(10);
1278         return NF_STOLEN;
1279 }
1280 
1281 #ifdef CONFIG_IP_VS_IPV6
1282 int
1283 ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
1284                      struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
1285 {
1286         struct netns_ipvs *ipvs = cp->ipvs;
1287         struct net *net = ipvs->net;
1288         struct rt6_info *rt;            /* Route to the other host */
1289         struct in6_addr saddr;          /* Source for tunnel */
1290         struct net_device *tdev;        /* Device to other host */
1291         __u8 next_protocol = 0;
1292         __u32 payload_len = 0;
1293         __u8 dsfield = 0;
1294         __u8 ttl = 0;
1295         struct ipv6hdr  *iph;           /* Our new IP header */
1296         unsigned int max_headroom;      /* The extra header space needed */
1297         int ret, local;
1298         int tun_type, gso_type;
1299         int tun_flags;
1300 
1301         EnterFunction(10);
1302 
1303         local = __ip_vs_get_out_rt_v6(ipvs, cp->af, skb, cp->dest,
1304                                       &cp->daddr.in6,
1305                                       &saddr, ipvsh, 1,
1306                                       IP_VS_RT_MODE_LOCAL |
1307                                       IP_VS_RT_MODE_NON_LOCAL |
1308                                       IP_VS_RT_MODE_TUNNEL);
1309         if (local < 0)
1310                 goto tx_error;
1311         if (local)
1312                 return ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 1);
1313 
1314         rt = (struct rt6_info *) skb_dst(skb);
1315         tdev = rt->dst.dev;
1316 
1317         /*
1318          * Okay, now see if we can stuff it in the buffer as-is.
1319          */
1320         max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct ipv6hdr);
1321 
1322         tun_type = cp->dest->tun_type;
1323         tun_flags = cp->dest->tun_flags;
1324 
1325         if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
1326                 size_t gue_hdrlen, gue_optlen = 0;
1327 
1328                 if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
1329                     skb->ip_summed == CHECKSUM_PARTIAL) {
1330                         gue_optlen += GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
1331                 }
1332                 gue_hdrlen = sizeof(struct guehdr) + gue_optlen;
1333 
1334                 max_headroom += sizeof(struct udphdr) + gue_hdrlen;
1335         } else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
1336                 size_t gre_hdrlen;
1337                 __be16 tflags = 0;
1338 
1339                 if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
1340                         tflags |= TUNNEL_CSUM;
1341                 gre_hdrlen = gre_calc_hlen(tflags);
1342 
1343                 max_headroom += gre_hdrlen;
1344         }
1345 
1346         skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom,
1347                                          &next_protocol, &payload_len,
1348                                          &dsfield, &ttl, NULL);
1349         if (IS_ERR(skb))
1350                 goto tx_error;
1351 
1352         gso_type = __tun_gso_type_mask(AF_INET6, cp->af);
1353         if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
1354                 if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM) ||
1355                     (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM))
1356                         gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
1357                 else
1358                         gso_type |= SKB_GSO_UDP_TUNNEL;
1359                 if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
1360                     skb->ip_summed == CHECKSUM_PARTIAL) {
1361                         gso_type |= SKB_GSO_TUNNEL_REMCSUM;
1362                 }
1363         } else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
1364                 if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
1365                         gso_type |= SKB_GSO_GRE_CSUM;
1366                 else
1367                         gso_type |= SKB_GSO_GRE;
1368         }
1369 
1370         if (iptunnel_handle_offloads(skb, gso_type))
1371                 goto tx_error;
1372 
1373         skb->transport_header = skb->network_header;
1374 
1375         skb_set_inner_ipproto(skb, next_protocol);
1376 
1377         if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
1378                 bool check = false;
1379 
1380                 if (ipvs_gue_encap(net, skb, cp, &next_protocol))
1381                         goto tx_error;
1382 
1383                 if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM) ||
1384                     (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM))
1385                         check = true;
1386 
1387                 udp6_set_csum(!check, skb, &saddr, &cp->daddr.in6, skb->len);
1388         } else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE)
1389                 ipvs_gre_encap(net, skb, cp, &next_protocol);
1390 
1391         skb_push(skb, sizeof(struct ipv6hdr));
1392         skb_reset_network_header(skb);
1393         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1394 
1395         /*
1396          *      Push down and install the IPIP header.
1397          */
1398         iph                     =       ipv6_hdr(skb);
1399         iph->version            =       6;
1400         iph->nexthdr            =       next_protocol;
1401         iph->payload_len        =       htons(payload_len);
1402         memset(&iph->flow_lbl, 0, sizeof(iph->flow_lbl));
1403         ipv6_change_dsfield(iph, 0, dsfield);
1404         iph->daddr = cp->daddr.in6;
1405         iph->saddr = saddr;
1406         iph->hop_limit          =       ttl;
1407 
1408         /* Another hack: avoid icmp_send in ip_fragment */
1409         skb->ignore_df = 1;
1410 
1411         ret = ip_vs_tunnel_xmit_prepare(skb, cp);
1412         if (ret == NF_ACCEPT)
1413                 ip6_local_out(net, skb->sk, skb);
1414         else if (ret == NF_DROP)
1415                 kfree_skb(skb);
1416 
1417         LeaveFunction(10);
1418 
1419         return NF_STOLEN;
1420 
1421 tx_error:
1422         if (!IS_ERR(skb))
1423                 kfree_skb(skb);
1424         LeaveFunction(10);
1425         return NF_STOLEN;
1426 }
1427 #endif
1428 
1429 
1430 /*
1431  *      Direct Routing transmitter
1432  *      Used for ANY protocol
1433  */
1434 int
1435 ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
1436               struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
1437 {
1438         int local;
1439 
1440         EnterFunction(10);
1441 
1442         local = __ip_vs_get_out_rt(cp->ipvs, cp->af, skb, cp->dest, cp->daddr.ip,
1443                                    IP_VS_RT_MODE_LOCAL |
1444                                    IP_VS_RT_MODE_NON_LOCAL |
1445                                    IP_VS_RT_MODE_KNOWN_NH, NULL, ipvsh);
1446         if (local < 0)
1447                 goto tx_error;
1448         if (local)
1449                 return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1);
1450 
1451         ip_send_check(ip_hdr(skb));
1452 
1453         /* Another hack: avoid icmp_send in ip_fragment */
1454         skb->ignore_df = 1;
1455 
1456         ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 0);
1457 
1458         LeaveFunction(10);
1459         return NF_STOLEN;
1460 
1461   tx_error:
1462         kfree_skb(skb);
1463         LeaveFunction(10);
1464         return NF_STOLEN;
1465 }
1466 
1467 #ifdef CONFIG_IP_VS_IPV6
1468 int
1469 ip_vs_dr_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
1470                  struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
1471 {
1472         int local;
1473 
1474         EnterFunction(10);
1475 
1476         local = __ip_vs_get_out_rt_v6(cp->ipvs, cp->af, skb, cp->dest,
1477                                       &cp->daddr.in6,
1478                                       NULL, ipvsh, 0,
1479                                       IP_VS_RT_MODE_LOCAL |
1480                                       IP_VS_RT_MODE_NON_LOCAL |
1481                                       IP_VS_RT_MODE_KNOWN_NH);
1482         if (local < 0)
1483                 goto tx_error;
1484         if (local)
1485                 return ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 1);
1486 
1487         /* Another hack: avoid icmp_send in ip_fragment */
1488         skb->ignore_df = 1;
1489 
1490         ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 0);
1491 
1492         LeaveFunction(10);
1493         return NF_STOLEN;
1494 
1495 tx_error:
1496         kfree_skb(skb);
1497         LeaveFunction(10);
1498         return NF_STOLEN;
1499 }
1500 #endif
1501 
1502 
1503 /*
1504  *      ICMP packet transmitter
1505  *      called by the ip_vs_in_icmp
1506  */
1507 int
1508 ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
1509                 struct ip_vs_protocol *pp, int offset, unsigned int hooknum,
1510                 struct ip_vs_iphdr *iph)
1511 {
1512         struct rtable   *rt;    /* Route to the other host */
1513         int rc;
1514         int local;
1515         int rt_mode, was_input;
1516 
1517         EnterFunction(10);
1518 
1519         /* The ICMP packet for VS/TUN, VS/DR and LOCALNODE will be
1520            forwarded directly here, because there is no need to
1521            translate address/port back */
1522         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) {
1523                 if (cp->packet_xmit)
1524                         rc = cp->packet_xmit(skb, cp, pp, iph);
1525                 else
1526                         rc = NF_ACCEPT;
1527                 /* do not touch skb anymore */
1528                 atomic_inc(&cp->in_pkts);
1529                 goto out;
1530         }
1531 
1532         /*
1533          * mangle and send the packet here (only for VS/NAT)
1534          */
1535         was_input = rt_is_input_route(skb_rtable(skb));
1536 
1537         /* LOCALNODE from FORWARD hook is not supported */
1538         rt_mode = (hooknum != NF_INET_FORWARD) ?
1539                   IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL |
1540                   IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL;
1541         local = __ip_vs_get_out_rt(cp->ipvs, cp->af, skb, cp->dest, cp->daddr.ip, rt_mode,
1542                                    NULL, iph);
1543         if (local < 0)
1544                 goto tx_error;
1545         rt = skb_rtable(skb);
1546 
1547         /*
1548          * Avoid duplicate tuple in reply direction for NAT traffic
1549          * to local address when connection is sync-ed
1550          */
1551 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
1552         if (cp->flags & IP_VS_CONN_F_SYNC && local) {
1553                 enum ip_conntrack_info ctinfo;
1554                 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1555 
1556                 if (ct) {
1557                         IP_VS_DBG(10, "%s(): "
1558                                   "stopping DNAT to local address %pI4\n",
1559                                   __func__, &cp->daddr.ip);
1560                         goto tx_error;
1561                 }
1562         }
1563 #endif
1564 
1565         /* From world but DNAT to loopback address? */
1566         if (local && ipv4_is_loopback(cp->daddr.ip) && was_input) {
1567                 IP_VS_DBG(1, "%s(): "
1568                           "stopping DNAT to loopback %pI4\n",
1569                           __func__, &cp->daddr.ip);
1570                 goto tx_error;
1571         }
1572 
1573         /* copy-on-write the packet before mangling it */
1574         if (skb_ensure_writable(skb, offset))
1575                 goto tx_error;
1576 
1577         if (skb_cow(skb, rt->dst.dev->hard_header_len))
1578                 goto tx_error;
1579 
1580         ip_vs_nat_icmp(skb, pp, cp, 0);
1581 
1582         /* Another hack: avoid icmp_send in ip_fragment */
1583         skb->ignore_df = 1;
1584 
1585         rc = ip_vs_nat_send_or_cont(NFPROTO_IPV4, skb, cp, local);
1586         goto out;
1587 
1588   tx_error:
1589         kfree_skb(skb);
1590         rc = NF_STOLEN;
1591   out:
1592         LeaveFunction(10);
1593         return rc;
1594 }
1595 
1596 #ifdef CONFIG_IP_VS_IPV6
1597 int
1598 ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
1599                 struct ip_vs_protocol *pp, int offset, unsigned int hooknum,
1600                 struct ip_vs_iphdr *ipvsh)
1601 {
1602         struct rt6_info *rt;    /* Route to the other host */
1603         int rc;
1604         int local;
1605         int rt_mode;
1606 
1607         EnterFunction(10);
1608 
1609         /* The ICMP packet for VS/TUN, VS/DR and LOCALNODE will be
1610            forwarded directly here, because there is no need to
1611            translate address/port back */
1612         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) {
1613                 if (cp->packet_xmit)
1614                         rc = cp->packet_xmit(skb, cp, pp, ipvsh);
1615                 else
1616                         rc = NF_ACCEPT;
1617                 /* do not touch skb anymore */
1618                 atomic_inc(&cp->in_pkts);
1619                 goto out;
1620         }
1621 
1622         /*
1623          * mangle and send the packet here (only for VS/NAT)
1624          */
1625 
1626         /* LOCALNODE from FORWARD hook is not supported */
1627         rt_mode = (hooknum != NF_INET_FORWARD) ?
1628                   IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL |
1629                   IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL;
1630         local = __ip_vs_get_out_rt_v6(cp->ipvs, cp->af, skb, cp->dest,
1631                                       &cp->daddr.in6, NULL, ipvsh, 0, rt_mode);
1632         if (local < 0)
1633                 goto tx_error;
1634         rt = (struct rt6_info *) skb_dst(skb);
1635         /*
1636          * Avoid duplicate tuple in reply direction for NAT traffic
1637          * to local address when connection is sync-ed
1638          */
1639 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
1640         if (cp->flags & IP_VS_CONN_F_SYNC && local) {
1641                 enum ip_conntrack_info ctinfo;
1642                 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1643 
1644                 if (ct) {
1645                         IP_VS_DBG(10, "%s(): "
1646                                   "stopping DNAT to local address %pI6\n",
1647                                   __func__, &cp->daddr.in6);
1648                         goto tx_error;
1649                 }
1650         }
1651 #endif
1652 
1653         /* From world but DNAT to loopback address? */
1654         if (local && skb->dev && !(skb->dev->flags & IFF_LOOPBACK) &&
1655             ipv6_addr_type(&cp->daddr.in6) & IPV6_ADDR_LOOPBACK) {
1656                 IP_VS_DBG(1, "%s(): "
1657                           "stopping DNAT to loopback %pI6\n",
1658                           __func__, &cp->daddr.in6);
1659                 goto tx_error;
1660         }
1661 
1662         /* copy-on-write the packet before mangling it */
1663         if (skb_ensure_writable(skb, offset))
1664                 goto tx_error;
1665 
1666         if (skb_cow(skb, rt->dst.dev->hard_header_len))
1667                 goto tx_error;
1668 
1669         ip_vs_nat_icmp_v6(skb, pp, cp, 0);
1670 
1671         /* Another hack: avoid icmp_send in ip_fragment */
1672         skb->ignore_df = 1;
1673 
1674         rc = ip_vs_nat_send_or_cont(NFPROTO_IPV6, skb, cp, local);
1675         goto out;
1676 
1677 tx_error:
1678         kfree_skb(skb);
1679         rc = NF_STOLEN;
1680 out:
1681         LeaveFunction(10);
1682         return rc;
1683 }
1684 #endif
1685 

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