xref: /openbmc/linux/net/ipv6/ip6_output.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  *	IPv6 output functions
3  *	Linux INET6 implementation
4  *
5  *	Authors:
6  *	Pedro Roque		<roque@di.fc.ul.pt>
7  *
8  *	$Id: ip6_output.c,v 1.34 2002/02/01 22:01:04 davem Exp $
9  *
10  *	Based on linux/net/ipv4/ip_output.c
11  *
12  *	This program is free software; you can redistribute it and/or
13  *      modify it under the terms of the GNU General Public License
14  *      as published by the Free Software Foundation; either version
15  *      2 of the License, or (at your option) any later version.
16  *
17  *	Changes:
18  *	A.N.Kuznetsov	:	airthmetics in fragmentation.
19  *				extension headers are implemented.
20  *				route changes now work.
21  *				ip6_forward does not confuse sniffers.
22  *				etc.
23  *
24  *      H. von Brand    :       Added missing #include <linux/string.h>
25  *	Imran Patel	: 	frag id should be in NBO
26  *      Kazunori MIYAZAWA @USAGI
27  *			:       add ip6_append_data and related functions
28  *				for datagram xmit
29  */
30 
31 #include <linux/errno.h>
32 #include <linux/types.h>
33 #include <linux/string.h>
34 #include <linux/socket.h>
35 #include <linux/net.h>
36 #include <linux/netdevice.h>
37 #include <linux/if_arp.h>
38 #include <linux/in6.h>
39 #include <linux/tcp.h>
40 #include <linux/route.h>
41 #include <linux/module.h>
42 
43 #include <linux/netfilter.h>
44 #include <linux/netfilter_ipv6.h>
45 
46 #include <net/sock.h>
47 #include <net/snmp.h>
48 
49 #include <net/ipv6.h>
50 #include <net/ndisc.h>
51 #include <net/protocol.h>
52 #include <net/ip6_route.h>
53 #include <net/addrconf.h>
54 #include <net/rawv6.h>
55 #include <net/icmp.h>
56 #include <net/xfrm.h>
57 #include <net/checksum.h>
58 
59 static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *));
60 
61 static __inline__ void ipv6_select_ident(struct sk_buff *skb, struct frag_hdr *fhdr)
62 {
63 	static u32 ipv6_fragmentation_id = 1;
64 	static DEFINE_SPINLOCK(ip6_id_lock);
65 
66 	spin_lock_bh(&ip6_id_lock);
67 	fhdr->identification = htonl(ipv6_fragmentation_id);
68 	if (++ipv6_fragmentation_id == 0)
69 		ipv6_fragmentation_id = 1;
70 	spin_unlock_bh(&ip6_id_lock);
71 }
72 
73 static inline int ip6_output_finish(struct sk_buff *skb)
74 {
75 	struct dst_entry *dst = skb->dst;
76 
77 	if (dst->hh)
78 		return neigh_hh_output(dst->hh, skb);
79 	else if (dst->neighbour)
80 		return dst->neighbour->output(skb);
81 
82 	IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
83 	kfree_skb(skb);
84 	return -EINVAL;
85 
86 }
87 
88 /* dev_loopback_xmit for use with netfilter. */
89 static int ip6_dev_loopback_xmit(struct sk_buff *newskb)
90 {
91 	skb_reset_mac_header(newskb);
92 	__skb_pull(newskb, skb_network_offset(newskb));
93 	newskb->pkt_type = PACKET_LOOPBACK;
94 	newskb->ip_summed = CHECKSUM_UNNECESSARY;
95 	BUG_TRAP(newskb->dst);
96 
97 	netif_rx(newskb);
98 	return 0;
99 }
100 
101 
102 static int ip6_output2(struct sk_buff *skb)
103 {
104 	struct dst_entry *dst = skb->dst;
105 	struct net_device *dev = dst->dev;
106 
107 	skb->protocol = htons(ETH_P_IPV6);
108 	skb->dev = dev;
109 
110 	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
111 		struct ipv6_pinfo* np = skb->sk ? inet6_sk(skb->sk) : NULL;
112 		struct inet6_dev *idev = ip6_dst_idev(skb->dst);
113 
114 		if (!(dev->flags & IFF_LOOPBACK) && (!np || np->mc_loop) &&
115 		    ipv6_chk_mcast_addr(dev, &ipv6_hdr(skb)->daddr,
116 					&ipv6_hdr(skb)->saddr)) {
117 			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
118 
119 			/* Do not check for IFF_ALLMULTI; multicast routing
120 			   is not supported in any case.
121 			 */
122 			if (newskb)
123 				NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, newskb, NULL,
124 					newskb->dev,
125 					ip6_dev_loopback_xmit);
126 
127 			if (ipv6_hdr(skb)->hop_limit == 0) {
128 				IP6_INC_STATS(idev, IPSTATS_MIB_OUTDISCARDS);
129 				kfree_skb(skb);
130 				return 0;
131 			}
132 		}
133 
134 		IP6_INC_STATS(idev, IPSTATS_MIB_OUTMCASTPKTS);
135 	}
136 
137 	return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb,NULL, skb->dev,ip6_output_finish);
138 }
139 
140 static inline int ip6_skb_dst_mtu(struct sk_buff *skb)
141 {
142 	struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
143 
144 	return (np && np->pmtudisc == IPV6_PMTUDISC_PROBE) ?
145 	       skb->dst->dev->mtu : dst_mtu(skb->dst);
146 }
147 
148 int ip6_output(struct sk_buff *skb)
149 {
150 	if ((skb->len > ip6_skb_dst_mtu(skb) && !skb_is_gso(skb)) ||
151 				dst_allfrag(skb->dst))
152 		return ip6_fragment(skb, ip6_output2);
153 	else
154 		return ip6_output2(skb);
155 }
156 
157 /*
158  *	xmit an sk_buff (used by TCP)
159  */
160 
161 int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
162 	     struct ipv6_txoptions *opt, int ipfragok)
163 {
164 	struct ipv6_pinfo *np = inet6_sk(sk);
165 	struct in6_addr *first_hop = &fl->fl6_dst;
166 	struct dst_entry *dst = skb->dst;
167 	struct ipv6hdr *hdr;
168 	u8  proto = fl->proto;
169 	int seg_len = skb->len;
170 	int hlimit, tclass;
171 	u32 mtu;
172 
173 	if (opt) {
174 		int head_room;
175 
176 		/* First: exthdrs may take lots of space (~8K for now)
177 		   MAX_HEADER is not enough.
178 		 */
179 		head_room = opt->opt_nflen + opt->opt_flen;
180 		seg_len += head_room;
181 		head_room += sizeof(struct ipv6hdr) + LL_RESERVED_SPACE(dst->dev);
182 
183 		if (skb_headroom(skb) < head_room) {
184 			struct sk_buff *skb2 = skb_realloc_headroom(skb, head_room);
185 			if (skb2 == NULL) {
186 				IP6_INC_STATS(ip6_dst_idev(skb->dst),
187 					      IPSTATS_MIB_OUTDISCARDS);
188 				kfree_skb(skb);
189 				return -ENOBUFS;
190 			}
191 			kfree_skb(skb);
192 			skb = skb2;
193 			if (sk)
194 				skb_set_owner_w(skb, sk);
195 		}
196 		if (opt->opt_flen)
197 			ipv6_push_frag_opts(skb, opt, &proto);
198 		if (opt->opt_nflen)
199 			ipv6_push_nfrag_opts(skb, opt, &proto, &first_hop);
200 	}
201 
202 	skb_push(skb, sizeof(struct ipv6hdr));
203 	skb_reset_network_header(skb);
204 	hdr = ipv6_hdr(skb);
205 
206 	/*
207 	 *	Fill in the IPv6 header
208 	 */
209 
210 	hlimit = -1;
211 	if (np)
212 		hlimit = np->hop_limit;
213 	if (hlimit < 0)
214 		hlimit = dst_metric(dst, RTAX_HOPLIMIT);
215 	if (hlimit < 0)
216 		hlimit = ipv6_get_hoplimit(dst->dev);
217 
218 	tclass = -1;
219 	if (np)
220 		tclass = np->tclass;
221 	if (tclass < 0)
222 		tclass = 0;
223 
224 	*(__be32 *)hdr = htonl(0x60000000 | (tclass << 20)) | fl->fl6_flowlabel;
225 
226 	hdr->payload_len = htons(seg_len);
227 	hdr->nexthdr = proto;
228 	hdr->hop_limit = hlimit;
229 
230 	ipv6_addr_copy(&hdr->saddr, &fl->fl6_src);
231 	ipv6_addr_copy(&hdr->daddr, first_hop);
232 
233 	skb->priority = sk->sk_priority;
234 
235 	mtu = dst_mtu(dst);
236 	if ((skb->len <= mtu) || ipfragok || skb_is_gso(skb)) {
237 		IP6_INC_STATS(ip6_dst_idev(skb->dst),
238 			      IPSTATS_MIB_OUTREQUESTS);
239 		return NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, dst->dev,
240 				dst_output);
241 	}
242 
243 	if (net_ratelimit())
244 		printk(KERN_DEBUG "IPv6: sending pkt_too_big to self\n");
245 	skb->dev = dst->dev;
246 	icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
247 	IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS);
248 	kfree_skb(skb);
249 	return -EMSGSIZE;
250 }
251 
252 EXPORT_SYMBOL(ip6_xmit);
253 
254 /*
255  *	To avoid extra problems ND packets are send through this
256  *	routine. It's code duplication but I really want to avoid
257  *	extra checks since ipv6_build_header is used by TCP (which
258  *	is for us performance critical)
259  */
260 
261 int ip6_nd_hdr(struct sock *sk, struct sk_buff *skb, struct net_device *dev,
262 	       struct in6_addr *saddr, struct in6_addr *daddr,
263 	       int proto, int len)
264 {
265 	struct ipv6_pinfo *np = inet6_sk(sk);
266 	struct ipv6hdr *hdr;
267 	int totlen;
268 
269 	skb->protocol = htons(ETH_P_IPV6);
270 	skb->dev = dev;
271 
272 	totlen = len + sizeof(struct ipv6hdr);
273 
274 	skb_reset_network_header(skb);
275 	skb_put(skb, sizeof(struct ipv6hdr));
276 	hdr = ipv6_hdr(skb);
277 
278 	*(__be32*)hdr = htonl(0x60000000);
279 
280 	hdr->payload_len = htons(len);
281 	hdr->nexthdr = proto;
282 	hdr->hop_limit = np->hop_limit;
283 
284 	ipv6_addr_copy(&hdr->saddr, saddr);
285 	ipv6_addr_copy(&hdr->daddr, daddr);
286 
287 	return 0;
288 }
289 
290 static int ip6_call_ra_chain(struct sk_buff *skb, int sel)
291 {
292 	struct ip6_ra_chain *ra;
293 	struct sock *last = NULL;
294 
295 	read_lock(&ip6_ra_lock);
296 	for (ra = ip6_ra_chain; ra; ra = ra->next) {
297 		struct sock *sk = ra->sk;
298 		if (sk && ra->sel == sel &&
299 		    (!sk->sk_bound_dev_if ||
300 		     sk->sk_bound_dev_if == skb->dev->ifindex)) {
301 			if (last) {
302 				struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
303 				if (skb2)
304 					rawv6_rcv(last, skb2);
305 			}
306 			last = sk;
307 		}
308 	}
309 
310 	if (last) {
311 		rawv6_rcv(last, skb);
312 		read_unlock(&ip6_ra_lock);
313 		return 1;
314 	}
315 	read_unlock(&ip6_ra_lock);
316 	return 0;
317 }
318 
319 static int ip6_forward_proxy_check(struct sk_buff *skb)
320 {
321 	struct ipv6hdr *hdr = ipv6_hdr(skb);
322 	u8 nexthdr = hdr->nexthdr;
323 	int offset;
324 
325 	if (ipv6_ext_hdr(nexthdr)) {
326 		offset = ipv6_skip_exthdr(skb, sizeof(*hdr), &nexthdr);
327 		if (offset < 0)
328 			return 0;
329 	} else
330 		offset = sizeof(struct ipv6hdr);
331 
332 	if (nexthdr == IPPROTO_ICMPV6) {
333 		struct icmp6hdr *icmp6;
334 
335 		if (!pskb_may_pull(skb, (skb_network_header(skb) +
336 					 offset + 1 - skb->data)))
337 			return 0;
338 
339 		icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
340 
341 		switch (icmp6->icmp6_type) {
342 		case NDISC_ROUTER_SOLICITATION:
343 		case NDISC_ROUTER_ADVERTISEMENT:
344 		case NDISC_NEIGHBOUR_SOLICITATION:
345 		case NDISC_NEIGHBOUR_ADVERTISEMENT:
346 		case NDISC_REDIRECT:
347 			/* For reaction involving unicast neighbor discovery
348 			 * message destined to the proxied address, pass it to
349 			 * input function.
350 			 */
351 			return 1;
352 		default:
353 			break;
354 		}
355 	}
356 
357 	/*
358 	 * The proxying router can't forward traffic sent to a link-local
359 	 * address, so signal the sender and discard the packet. This
360 	 * behavior is clarified by the MIPv6 specification.
361 	 */
362 	if (ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) {
363 		dst_link_failure(skb);
364 		return -1;
365 	}
366 
367 	return 0;
368 }
369 
370 static inline int ip6_forward_finish(struct sk_buff *skb)
371 {
372 	return dst_output(skb);
373 }
374 
375 int ip6_forward(struct sk_buff *skb)
376 {
377 	struct dst_entry *dst = skb->dst;
378 	struct ipv6hdr *hdr = ipv6_hdr(skb);
379 	struct inet6_skb_parm *opt = IP6CB(skb);
380 
381 	if (ipv6_devconf.forwarding == 0)
382 		goto error;
383 
384 	if (!xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
385 		IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
386 		goto drop;
387 	}
388 
389 	skb_forward_csum(skb);
390 
391 	/*
392 	 *	We DO NOT make any processing on
393 	 *	RA packets, pushing them to user level AS IS
394 	 *	without ane WARRANTY that application will be able
395 	 *	to interpret them. The reason is that we
396 	 *	cannot make anything clever here.
397 	 *
398 	 *	We are not end-node, so that if packet contains
399 	 *	AH/ESP, we cannot make anything.
400 	 *	Defragmentation also would be mistake, RA packets
401 	 *	cannot be fragmented, because there is no warranty
402 	 *	that different fragments will go along one path. --ANK
403 	 */
404 	if (opt->ra) {
405 		u8 *ptr = skb_network_header(skb) + opt->ra;
406 		if (ip6_call_ra_chain(skb, (ptr[2]<<8) + ptr[3]))
407 			return 0;
408 	}
409 
410 	/*
411 	 *	check and decrement ttl
412 	 */
413 	if (hdr->hop_limit <= 1) {
414 		/* Force OUTPUT device used as source address */
415 		skb->dev = dst->dev;
416 		icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
417 			    0, skb->dev);
418 		IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
419 
420 		kfree_skb(skb);
421 		return -ETIMEDOUT;
422 	}
423 
424 	/* XXX: idev->cnf.proxy_ndp? */
425 	if (ipv6_devconf.proxy_ndp &&
426 	    pneigh_lookup(&nd_tbl, &hdr->daddr, skb->dev, 0)) {
427 		int proxied = ip6_forward_proxy_check(skb);
428 		if (proxied > 0)
429 			return ip6_input(skb);
430 		else if (proxied < 0) {
431 			IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
432 			goto drop;
433 		}
434 	}
435 
436 	if (!xfrm6_route_forward(skb)) {
437 		IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
438 		goto drop;
439 	}
440 	dst = skb->dst;
441 
442 	/* IPv6 specs say nothing about it, but it is clear that we cannot
443 	   send redirects to source routed frames.
444 	 */
445 	if (skb->dev == dst->dev && dst->neighbour && opt->srcrt == 0) {
446 		struct in6_addr *target = NULL;
447 		struct rt6_info *rt;
448 		struct neighbour *n = dst->neighbour;
449 
450 		/*
451 		 *	incoming and outgoing devices are the same
452 		 *	send a redirect.
453 		 */
454 
455 		rt = (struct rt6_info *) dst;
456 		if ((rt->rt6i_flags & RTF_GATEWAY))
457 			target = (struct in6_addr*)&n->primary_key;
458 		else
459 			target = &hdr->daddr;
460 
461 		/* Limit redirects both by destination (here)
462 		   and by source (inside ndisc_send_redirect)
463 		 */
464 		if (xrlim_allow(dst, 1*HZ))
465 			ndisc_send_redirect(skb, n, target);
466 	} else {
467 		int addrtype = ipv6_addr_type(&hdr->saddr);
468 
469 		/* This check is security critical. */
470 		if (addrtype & (IPV6_ADDR_MULTICAST|IPV6_ADDR_LOOPBACK))
471 			goto error;
472 		if (addrtype & IPV6_ADDR_LINKLOCAL) {
473 			icmpv6_send(skb, ICMPV6_DEST_UNREACH,
474 				ICMPV6_NOT_NEIGHBOUR, 0, skb->dev);
475 			goto error;
476 		}
477 	}
478 
479 	if (skb->len > dst_mtu(dst)) {
480 		/* Again, force OUTPUT device used as source address */
481 		skb->dev = dst->dev;
482 		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, dst_mtu(dst), skb->dev);
483 		IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_INTOOBIGERRORS);
484 		IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_FRAGFAILS);
485 		kfree_skb(skb);
486 		return -EMSGSIZE;
487 	}
488 
489 	if (skb_cow(skb, dst->dev->hard_header_len)) {
490 		IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS);
491 		goto drop;
492 	}
493 
494 	hdr = ipv6_hdr(skb);
495 
496 	/* Mangling hops number delayed to point after skb COW */
497 
498 	hdr->hop_limit--;
499 
500 	IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
501 	return NF_HOOK(PF_INET6,NF_IP6_FORWARD, skb, skb->dev, dst->dev, ip6_forward_finish);
502 
503 error:
504 	IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_INADDRERRORS);
505 drop:
506 	kfree_skb(skb);
507 	return -EINVAL;
508 }
509 
510 static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
511 {
512 	to->pkt_type = from->pkt_type;
513 	to->priority = from->priority;
514 	to->protocol = from->protocol;
515 	dst_release(to->dst);
516 	to->dst = dst_clone(from->dst);
517 	to->dev = from->dev;
518 	to->mark = from->mark;
519 
520 #ifdef CONFIG_NET_SCHED
521 	to->tc_index = from->tc_index;
522 #endif
523 	nf_copy(to, from);
524 	skb_copy_secmark(to, from);
525 }
526 
527 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
528 {
529 	u16 offset = sizeof(struct ipv6hdr);
530 	struct ipv6_opt_hdr *exthdr =
531 				(struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
532 	unsigned int packet_len = skb->tail - skb->network_header;
533 	int found_rhdr = 0;
534 	*nexthdr = &ipv6_hdr(skb)->nexthdr;
535 
536 	while (offset + 1 <= packet_len) {
537 
538 		switch (**nexthdr) {
539 
540 		case NEXTHDR_HOP:
541 			break;
542 		case NEXTHDR_ROUTING:
543 			found_rhdr = 1;
544 			break;
545 		case NEXTHDR_DEST:
546 #ifdef CONFIG_IPV6_MIP6
547 			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
548 				break;
549 #endif
550 			if (found_rhdr)
551 				return offset;
552 			break;
553 		default :
554 			return offset;
555 		}
556 
557 		offset += ipv6_optlen(exthdr);
558 		*nexthdr = &exthdr->nexthdr;
559 		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
560 						 offset);
561 	}
562 
563 	return offset;
564 }
565 EXPORT_SYMBOL_GPL(ip6_find_1stfragopt);
566 
567 static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
568 {
569 	struct net_device *dev;
570 	struct sk_buff *frag;
571 	struct rt6_info *rt = (struct rt6_info*)skb->dst;
572 	struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
573 	struct ipv6hdr *tmp_hdr;
574 	struct frag_hdr *fh;
575 	unsigned int mtu, hlen, left, len;
576 	__be32 frag_id = 0;
577 	int ptr, offset = 0, err=0;
578 	u8 *prevhdr, nexthdr = 0;
579 
580 	dev = rt->u.dst.dev;
581 	hlen = ip6_find_1stfragopt(skb, &prevhdr);
582 	nexthdr = *prevhdr;
583 
584 	mtu = ip6_skb_dst_mtu(skb);
585 
586 	/* We must not fragment if the socket is set to force MTU discovery
587 	 * or if the skb it not generated by a local socket.  (This last
588 	 * check should be redundant, but it's free.)
589 	 */
590 	if (!np || np->pmtudisc >= IPV6_PMTUDISC_DO) {
591 		skb->dev = skb->dst->dev;
592 		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
593 		IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS);
594 		kfree_skb(skb);
595 		return -EMSGSIZE;
596 	}
597 
598 	if (np && np->frag_size < mtu) {
599 		if (np->frag_size)
600 			mtu = np->frag_size;
601 	}
602 	mtu -= hlen + sizeof(struct frag_hdr);
603 
604 	if (skb_shinfo(skb)->frag_list) {
605 		int first_len = skb_pagelen(skb);
606 
607 		if (first_len - hlen > mtu ||
608 		    ((first_len - hlen) & 7) ||
609 		    skb_cloned(skb))
610 			goto slow_path;
611 
612 		for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
613 			/* Correct geometry. */
614 			if (frag->len > mtu ||
615 			    ((frag->len & 7) && frag->next) ||
616 			    skb_headroom(frag) < hlen)
617 			    goto slow_path;
618 
619 			/* Partially cloned skb? */
620 			if (skb_shared(frag))
621 				goto slow_path;
622 
623 			BUG_ON(frag->sk);
624 			if (skb->sk) {
625 				sock_hold(skb->sk);
626 				frag->sk = skb->sk;
627 				frag->destructor = sock_wfree;
628 				skb->truesize -= frag->truesize;
629 			}
630 		}
631 
632 		err = 0;
633 		offset = 0;
634 		frag = skb_shinfo(skb)->frag_list;
635 		skb_shinfo(skb)->frag_list = NULL;
636 		/* BUILD HEADER */
637 
638 		*prevhdr = NEXTHDR_FRAGMENT;
639 		tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC);
640 		if (!tmp_hdr) {
641 			IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS);
642 			return -ENOMEM;
643 		}
644 
645 		__skb_pull(skb, hlen);
646 		fh = (struct frag_hdr*)__skb_push(skb, sizeof(struct frag_hdr));
647 		__skb_push(skb, hlen);
648 		skb_reset_network_header(skb);
649 		memcpy(skb_network_header(skb), tmp_hdr, hlen);
650 
651 		ipv6_select_ident(skb, fh);
652 		fh->nexthdr = nexthdr;
653 		fh->reserved = 0;
654 		fh->frag_off = htons(IP6_MF);
655 		frag_id = fh->identification;
656 
657 		first_len = skb_pagelen(skb);
658 		skb->data_len = first_len - skb_headlen(skb);
659 		skb->len = first_len;
660 		ipv6_hdr(skb)->payload_len = htons(first_len -
661 						   sizeof(struct ipv6hdr));
662 
663 		dst_hold(&rt->u.dst);
664 
665 		for (;;) {
666 			/* Prepare header of the next frame,
667 			 * before previous one went down. */
668 			if (frag) {
669 				frag->ip_summed = CHECKSUM_NONE;
670 				skb_reset_transport_header(frag);
671 				fh = (struct frag_hdr*)__skb_push(frag, sizeof(struct frag_hdr));
672 				__skb_push(frag, hlen);
673 				skb_reset_network_header(frag);
674 				memcpy(skb_network_header(frag), tmp_hdr,
675 				       hlen);
676 				offset += skb->len - hlen - sizeof(struct frag_hdr);
677 				fh->nexthdr = nexthdr;
678 				fh->reserved = 0;
679 				fh->frag_off = htons(offset);
680 				if (frag->next != NULL)
681 					fh->frag_off |= htons(IP6_MF);
682 				fh->identification = frag_id;
683 				ipv6_hdr(frag)->payload_len =
684 						htons(frag->len -
685 						      sizeof(struct ipv6hdr));
686 				ip6_copy_metadata(frag, skb);
687 			}
688 
689 			err = output(skb);
690 			if(!err)
691 				IP6_INC_STATS(ip6_dst_idev(&rt->u.dst), IPSTATS_MIB_FRAGCREATES);
692 
693 			if (err || !frag)
694 				break;
695 
696 			skb = frag;
697 			frag = skb->next;
698 			skb->next = NULL;
699 		}
700 
701 		kfree(tmp_hdr);
702 
703 		if (err == 0) {
704 			IP6_INC_STATS(ip6_dst_idev(&rt->u.dst), IPSTATS_MIB_FRAGOKS);
705 			dst_release(&rt->u.dst);
706 			return 0;
707 		}
708 
709 		while (frag) {
710 			skb = frag->next;
711 			kfree_skb(frag);
712 			frag = skb;
713 		}
714 
715 		IP6_INC_STATS(ip6_dst_idev(&rt->u.dst), IPSTATS_MIB_FRAGFAILS);
716 		dst_release(&rt->u.dst);
717 		return err;
718 	}
719 
720 slow_path:
721 	left = skb->len - hlen;		/* Space per frame */
722 	ptr = hlen;			/* Where to start from */
723 
724 	/*
725 	 *	Fragment the datagram.
726 	 */
727 
728 	*prevhdr = NEXTHDR_FRAGMENT;
729 
730 	/*
731 	 *	Keep copying data until we run out.
732 	 */
733 	while(left > 0)	{
734 		len = left;
735 		/* IF: it doesn't fit, use 'mtu' - the data space left */
736 		if (len > mtu)
737 			len = mtu;
738 		/* IF: we are not sending upto and including the packet end
739 		   then align the next start on an eight byte boundary */
740 		if (len < left)	{
741 			len &= ~7;
742 		}
743 		/*
744 		 *	Allocate buffer.
745 		 */
746 
747 		if ((frag = alloc_skb(len+hlen+sizeof(struct frag_hdr)+LL_RESERVED_SPACE(rt->u.dst.dev), GFP_ATOMIC)) == NULL) {
748 			NETDEBUG(KERN_INFO "IPv6: frag: no memory for new fragment!\n");
749 			IP6_INC_STATS(ip6_dst_idev(skb->dst),
750 				      IPSTATS_MIB_FRAGFAILS);
751 			err = -ENOMEM;
752 			goto fail;
753 		}
754 
755 		/*
756 		 *	Set up data on packet
757 		 */
758 
759 		ip6_copy_metadata(frag, skb);
760 		skb_reserve(frag, LL_RESERVED_SPACE(rt->u.dst.dev));
761 		skb_put(frag, len + hlen + sizeof(struct frag_hdr));
762 		skb_reset_network_header(frag);
763 		fh = (struct frag_hdr *)(skb_network_header(frag) + hlen);
764 		frag->transport_header = (frag->network_header + hlen +
765 					  sizeof(struct frag_hdr));
766 
767 		/*
768 		 *	Charge the memory for the fragment to any owner
769 		 *	it might possess
770 		 */
771 		if (skb->sk)
772 			skb_set_owner_w(frag, skb->sk);
773 
774 		/*
775 		 *	Copy the packet header into the new buffer.
776 		 */
777 		skb_copy_from_linear_data(skb, skb_network_header(frag), hlen);
778 
779 		/*
780 		 *	Build fragment header.
781 		 */
782 		fh->nexthdr = nexthdr;
783 		fh->reserved = 0;
784 		if (!frag_id) {
785 			ipv6_select_ident(skb, fh);
786 			frag_id = fh->identification;
787 		} else
788 			fh->identification = frag_id;
789 
790 		/*
791 		 *	Copy a block of the IP datagram.
792 		 */
793 		if (skb_copy_bits(skb, ptr, skb_transport_header(skb), len))
794 			BUG();
795 		left -= len;
796 
797 		fh->frag_off = htons(offset);
798 		if (left > 0)
799 			fh->frag_off |= htons(IP6_MF);
800 		ipv6_hdr(frag)->payload_len = htons(frag->len -
801 						    sizeof(struct ipv6hdr));
802 
803 		ptr += len;
804 		offset += len;
805 
806 		/*
807 		 *	Put this fragment into the sending queue.
808 		 */
809 		err = output(frag);
810 		if (err)
811 			goto fail;
812 
813 		IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGCREATES);
814 	}
815 	IP6_INC_STATS(ip6_dst_idev(skb->dst),
816 		      IPSTATS_MIB_FRAGOKS);
817 	kfree_skb(skb);
818 	return err;
819 
820 fail:
821 	IP6_INC_STATS(ip6_dst_idev(skb->dst),
822 		      IPSTATS_MIB_FRAGFAILS);
823 	kfree_skb(skb);
824 	return err;
825 }
826 
827 static inline int ip6_rt_check(struct rt6key *rt_key,
828 			       struct in6_addr *fl_addr,
829 			       struct in6_addr *addr_cache)
830 {
831 	return ((rt_key->plen != 128 || !ipv6_addr_equal(fl_addr, &rt_key->addr)) &&
832 		(addr_cache == NULL || !ipv6_addr_equal(fl_addr, addr_cache)));
833 }
834 
835 static struct dst_entry *ip6_sk_dst_check(struct sock *sk,
836 					  struct dst_entry *dst,
837 					  struct flowi *fl)
838 {
839 	struct ipv6_pinfo *np = inet6_sk(sk);
840 	struct rt6_info *rt = (struct rt6_info *)dst;
841 
842 	if (!dst)
843 		goto out;
844 
845 	/* Yes, checking route validity in not connected
846 	 * case is not very simple. Take into account,
847 	 * that we do not support routing by source, TOS,
848 	 * and MSG_DONTROUTE 		--ANK (980726)
849 	 *
850 	 * 1. ip6_rt_check(): If route was host route,
851 	 *    check that cached destination is current.
852 	 *    If it is network route, we still may
853 	 *    check its validity using saved pointer
854 	 *    to the last used address: daddr_cache.
855 	 *    We do not want to save whole address now,
856 	 *    (because main consumer of this service
857 	 *    is tcp, which has not this problem),
858 	 *    so that the last trick works only on connected
859 	 *    sockets.
860 	 * 2. oif also should be the same.
861 	 */
862 	if (ip6_rt_check(&rt->rt6i_dst, &fl->fl6_dst, np->daddr_cache) ||
863 #ifdef CONFIG_IPV6_SUBTREES
864 	    ip6_rt_check(&rt->rt6i_src, &fl->fl6_src, np->saddr_cache) ||
865 #endif
866 	    (fl->oif && fl->oif != dst->dev->ifindex)) {
867 		dst_release(dst);
868 		dst = NULL;
869 	}
870 
871 out:
872 	return dst;
873 }
874 
875 static int ip6_dst_lookup_tail(struct sock *sk,
876 			       struct dst_entry **dst, struct flowi *fl)
877 {
878 	int err;
879 
880 	if (*dst == NULL)
881 		*dst = ip6_route_output(sk, fl);
882 
883 	if ((err = (*dst)->error))
884 		goto out_err_release;
885 
886 	if (ipv6_addr_any(&fl->fl6_src)) {
887 		err = ipv6_get_saddr(*dst, &fl->fl6_dst, &fl->fl6_src);
888 		if (err)
889 			goto out_err_release;
890 	}
891 
892 #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
893 		/*
894 		 * Here if the dst entry we've looked up
895 		 * has a neighbour entry that is in the INCOMPLETE
896 		 * state and the src address from the flow is
897 		 * marked as OPTIMISTIC, we release the found
898 		 * dst entry and replace it instead with the
899 		 * dst entry of the nexthop router
900 		 */
901 		if (!((*dst)->neighbour->nud_state & NUD_VALID)) {
902 			struct inet6_ifaddr *ifp;
903 			struct flowi fl_gw;
904 			int redirect;
905 
906 			ifp = ipv6_get_ifaddr(&fl->fl6_src, (*dst)->dev, 1);
907 
908 			redirect = (ifp && ifp->flags & IFA_F_OPTIMISTIC);
909 			if (ifp)
910 				in6_ifa_put(ifp);
911 
912 			if (redirect) {
913 				/*
914 				 * We need to get the dst entry for the
915 				 * default router instead
916 				 */
917 				dst_release(*dst);
918 				memcpy(&fl_gw, fl, sizeof(struct flowi));
919 				memset(&fl_gw.fl6_dst, 0, sizeof(struct in6_addr));
920 				*dst = ip6_route_output(sk, &fl_gw);
921 				if ((err = (*dst)->error))
922 					goto out_err_release;
923 			}
924 		}
925 #endif
926 
927 	return 0;
928 
929 out_err_release:
930 	dst_release(*dst);
931 	*dst = NULL;
932 	return err;
933 }
934 
935 /**
936  *	ip6_dst_lookup - perform route lookup on flow
937  *	@sk: socket which provides route info
938  *	@dst: pointer to dst_entry * for result
939  *	@fl: flow to lookup
940  *
941  *	This function performs a route lookup on the given flow.
942  *
943  *	It returns zero on success, or a standard errno code on error.
944  */
945 int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
946 {
947 	*dst = NULL;
948 	return ip6_dst_lookup_tail(sk, dst, fl);
949 }
950 EXPORT_SYMBOL_GPL(ip6_dst_lookup);
951 
952 /**
953  *	ip6_sk_dst_lookup - perform socket cached route lookup on flow
954  *	@sk: socket which provides the dst cache and route info
955  *	@dst: pointer to dst_entry * for result
956  *	@fl: flow to lookup
957  *
958  *	This function performs a route lookup on the given flow with the
959  *	possibility of using the cached route in the socket if it is valid.
960  *	It will take the socket dst lock when operating on the dst cache.
961  *	As a result, this function can only be used in process context.
962  *
963  *	It returns zero on success, or a standard errno code on error.
964  */
965 int ip6_sk_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
966 {
967 	*dst = NULL;
968 	if (sk) {
969 		*dst = sk_dst_check(sk, inet6_sk(sk)->dst_cookie);
970 		*dst = ip6_sk_dst_check(sk, *dst, fl);
971 	}
972 
973 	return ip6_dst_lookup_tail(sk, dst, fl);
974 }
975 EXPORT_SYMBOL_GPL(ip6_sk_dst_lookup);
976 
977 static inline int ip6_ufo_append_data(struct sock *sk,
978 			int getfrag(void *from, char *to, int offset, int len,
979 			int odd, struct sk_buff *skb),
980 			void *from, int length, int hh_len, int fragheaderlen,
981 			int transhdrlen, int mtu,unsigned int flags)
982 
983 {
984 	struct sk_buff *skb;
985 	int err;
986 
987 	/* There is support for UDP large send offload by network
988 	 * device, so create one single skb packet containing complete
989 	 * udp datagram
990 	 */
991 	if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
992 		skb = sock_alloc_send_skb(sk,
993 			hh_len + fragheaderlen + transhdrlen + 20,
994 			(flags & MSG_DONTWAIT), &err);
995 		if (skb == NULL)
996 			return -ENOMEM;
997 
998 		/* reserve space for Hardware header */
999 		skb_reserve(skb, hh_len);
1000 
1001 		/* create space for UDP/IP header */
1002 		skb_put(skb,fragheaderlen + transhdrlen);
1003 
1004 		/* initialize network header pointer */
1005 		skb_reset_network_header(skb);
1006 
1007 		/* initialize protocol header pointer */
1008 		skb->transport_header = skb->network_header + fragheaderlen;
1009 
1010 		skb->ip_summed = CHECKSUM_PARTIAL;
1011 		skb->csum = 0;
1012 		sk->sk_sndmsg_off = 0;
1013 	}
1014 
1015 	err = skb_append_datato_frags(sk,skb, getfrag, from,
1016 				      (length - transhdrlen));
1017 	if (!err) {
1018 		struct frag_hdr fhdr;
1019 
1020 		/* specify the length of each IP datagram fragment*/
1021 		skb_shinfo(skb)->gso_size = mtu - fragheaderlen -
1022 					    sizeof(struct frag_hdr);
1023 		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1024 		ipv6_select_ident(skb, &fhdr);
1025 		skb_shinfo(skb)->ip6_frag_id = fhdr.identification;
1026 		__skb_queue_tail(&sk->sk_write_queue, skb);
1027 
1028 		return 0;
1029 	}
1030 	/* There is not enough support do UPD LSO,
1031 	 * so follow normal path
1032 	 */
1033 	kfree_skb(skb);
1034 
1035 	return err;
1036 }
1037 
1038 int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
1039 	int offset, int len, int odd, struct sk_buff *skb),
1040 	void *from, int length, int transhdrlen,
1041 	int hlimit, int tclass, struct ipv6_txoptions *opt, struct flowi *fl,
1042 	struct rt6_info *rt, unsigned int flags)
1043 {
1044 	struct inet_sock *inet = inet_sk(sk);
1045 	struct ipv6_pinfo *np = inet6_sk(sk);
1046 	struct sk_buff *skb;
1047 	unsigned int maxfraglen, fragheaderlen;
1048 	int exthdrlen;
1049 	int hh_len;
1050 	int mtu;
1051 	int copy;
1052 	int err;
1053 	int offset = 0;
1054 	int csummode = CHECKSUM_NONE;
1055 
1056 	if (flags&MSG_PROBE)
1057 		return 0;
1058 	if (skb_queue_empty(&sk->sk_write_queue)) {
1059 		/*
1060 		 * setup for corking
1061 		 */
1062 		if (opt) {
1063 			if (np->cork.opt == NULL) {
1064 				np->cork.opt = kmalloc(opt->tot_len,
1065 						       sk->sk_allocation);
1066 				if (unlikely(np->cork.opt == NULL))
1067 					return -ENOBUFS;
1068 			} else if (np->cork.opt->tot_len < opt->tot_len) {
1069 				printk(KERN_DEBUG "ip6_append_data: invalid option length\n");
1070 				return -EINVAL;
1071 			}
1072 			memcpy(np->cork.opt, opt, opt->tot_len);
1073 			inet->cork.flags |= IPCORK_OPT;
1074 			/* need source address above miyazawa*/
1075 		}
1076 		dst_hold(&rt->u.dst);
1077 		np->cork.rt = rt;
1078 		inet->cork.fl = *fl;
1079 		np->cork.hop_limit = hlimit;
1080 		np->cork.tclass = tclass;
1081 		mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
1082 		      rt->u.dst.dev->mtu : dst_mtu(rt->u.dst.path);
1083 		if (np->frag_size < mtu) {
1084 			if (np->frag_size)
1085 				mtu = np->frag_size;
1086 		}
1087 		inet->cork.fragsize = mtu;
1088 		if (dst_allfrag(rt->u.dst.path))
1089 			inet->cork.flags |= IPCORK_ALLFRAG;
1090 		inet->cork.length = 0;
1091 		sk->sk_sndmsg_page = NULL;
1092 		sk->sk_sndmsg_off = 0;
1093 		exthdrlen = rt->u.dst.header_len + (opt ? opt->opt_flen : 0);
1094 		length += exthdrlen;
1095 		transhdrlen += exthdrlen;
1096 	} else {
1097 		rt = np->cork.rt;
1098 		fl = &inet->cork.fl;
1099 		if (inet->cork.flags & IPCORK_OPT)
1100 			opt = np->cork.opt;
1101 		transhdrlen = 0;
1102 		exthdrlen = 0;
1103 		mtu = inet->cork.fragsize;
1104 	}
1105 
1106 	hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
1107 
1108 	fragheaderlen = sizeof(struct ipv6hdr) + rt->u.dst.nfheader_len + (opt ? opt->opt_nflen : 0);
1109 	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen - sizeof(struct frag_hdr);
1110 
1111 	if (mtu <= sizeof(struct ipv6hdr) + IPV6_MAXPLEN) {
1112 		if (inet->cork.length + length > sizeof(struct ipv6hdr) + IPV6_MAXPLEN - fragheaderlen) {
1113 			ipv6_local_error(sk, EMSGSIZE, fl, mtu-exthdrlen);
1114 			return -EMSGSIZE;
1115 		}
1116 	}
1117 
1118 	/*
1119 	 * Let's try using as much space as possible.
1120 	 * Use MTU if total length of the message fits into the MTU.
1121 	 * Otherwise, we need to reserve fragment header and
1122 	 * fragment alignment (= 8-15 octects, in total).
1123 	 *
1124 	 * Note that we may need to "move" the data from the tail of
1125 	 * of the buffer to the new fragment when we split
1126 	 * the message.
1127 	 *
1128 	 * FIXME: It may be fragmented into multiple chunks
1129 	 *        at once if non-fragmentable extension headers
1130 	 *        are too large.
1131 	 * --yoshfuji
1132 	 */
1133 
1134 	inet->cork.length += length;
1135 	if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&
1136 	    (rt->u.dst.dev->features & NETIF_F_UFO)) {
1137 
1138 		err = ip6_ufo_append_data(sk, getfrag, from, length, hh_len,
1139 					  fragheaderlen, transhdrlen, mtu,
1140 					  flags);
1141 		if (err)
1142 			goto error;
1143 		return 0;
1144 	}
1145 
1146 	if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1147 		goto alloc_new_skb;
1148 
1149 	while (length > 0) {
1150 		/* Check if the remaining data fits into current packet. */
1151 		copy = (inet->cork.length <= mtu && !(inet->cork.flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - skb->len;
1152 		if (copy < length)
1153 			copy = maxfraglen - skb->len;
1154 
1155 		if (copy <= 0) {
1156 			char *data;
1157 			unsigned int datalen;
1158 			unsigned int fraglen;
1159 			unsigned int fraggap;
1160 			unsigned int alloclen;
1161 			struct sk_buff *skb_prev;
1162 alloc_new_skb:
1163 			skb_prev = skb;
1164 
1165 			/* There's no room in the current skb */
1166 			if (skb_prev)
1167 				fraggap = skb_prev->len - maxfraglen;
1168 			else
1169 				fraggap = 0;
1170 
1171 			/*
1172 			 * If remaining data exceeds the mtu,
1173 			 * we know we need more fragment(s).
1174 			 */
1175 			datalen = length + fraggap;
1176 			if (datalen > (inet->cork.length <= mtu && !(inet->cork.flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
1177 				datalen = maxfraglen - fragheaderlen;
1178 
1179 			fraglen = datalen + fragheaderlen;
1180 			if ((flags & MSG_MORE) &&
1181 			    !(rt->u.dst.dev->features&NETIF_F_SG))
1182 				alloclen = mtu;
1183 			else
1184 				alloclen = datalen + fragheaderlen;
1185 
1186 			/*
1187 			 * The last fragment gets additional space at tail.
1188 			 * Note: we overallocate on fragments with MSG_MODE
1189 			 * because we have no idea if we're the last one.
1190 			 */
1191 			if (datalen == length + fraggap)
1192 				alloclen += rt->u.dst.trailer_len;
1193 
1194 			/*
1195 			 * We just reserve space for fragment header.
1196 			 * Note: this may be overallocation if the message
1197 			 * (without MSG_MORE) fits into the MTU.
1198 			 */
1199 			alloclen += sizeof(struct frag_hdr);
1200 
1201 			if (transhdrlen) {
1202 				skb = sock_alloc_send_skb(sk,
1203 						alloclen + hh_len,
1204 						(flags & MSG_DONTWAIT), &err);
1205 			} else {
1206 				skb = NULL;
1207 				if (atomic_read(&sk->sk_wmem_alloc) <=
1208 				    2 * sk->sk_sndbuf)
1209 					skb = sock_wmalloc(sk,
1210 							   alloclen + hh_len, 1,
1211 							   sk->sk_allocation);
1212 				if (unlikely(skb == NULL))
1213 					err = -ENOBUFS;
1214 			}
1215 			if (skb == NULL)
1216 				goto error;
1217 			/*
1218 			 *	Fill in the control structures
1219 			 */
1220 			skb->ip_summed = csummode;
1221 			skb->csum = 0;
1222 			/* reserve for fragmentation */
1223 			skb_reserve(skb, hh_len+sizeof(struct frag_hdr));
1224 
1225 			/*
1226 			 *	Find where to start putting bytes
1227 			 */
1228 			data = skb_put(skb, fraglen);
1229 			skb_set_network_header(skb, exthdrlen);
1230 			data += fragheaderlen;
1231 			skb->transport_header = (skb->network_header +
1232 						 fragheaderlen);
1233 			if (fraggap) {
1234 				skb->csum = skb_copy_and_csum_bits(
1235 					skb_prev, maxfraglen,
1236 					data + transhdrlen, fraggap, 0);
1237 				skb_prev->csum = csum_sub(skb_prev->csum,
1238 							  skb->csum);
1239 				data += fraggap;
1240 				pskb_trim_unique(skb_prev, maxfraglen);
1241 			}
1242 			copy = datalen - transhdrlen - fraggap;
1243 			if (copy < 0) {
1244 				err = -EINVAL;
1245 				kfree_skb(skb);
1246 				goto error;
1247 			} else if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1248 				err = -EFAULT;
1249 				kfree_skb(skb);
1250 				goto error;
1251 			}
1252 
1253 			offset += copy;
1254 			length -= datalen - fraggap;
1255 			transhdrlen = 0;
1256 			exthdrlen = 0;
1257 			csummode = CHECKSUM_NONE;
1258 
1259 			/*
1260 			 * Put the packet on the pending queue
1261 			 */
1262 			__skb_queue_tail(&sk->sk_write_queue, skb);
1263 			continue;
1264 		}
1265 
1266 		if (copy > length)
1267 			copy = length;
1268 
1269 		if (!(rt->u.dst.dev->features&NETIF_F_SG)) {
1270 			unsigned int off;
1271 
1272 			off = skb->len;
1273 			if (getfrag(from, skb_put(skb, copy),
1274 						offset, copy, off, skb) < 0) {
1275 				__skb_trim(skb, off);
1276 				err = -EFAULT;
1277 				goto error;
1278 			}
1279 		} else {
1280 			int i = skb_shinfo(skb)->nr_frags;
1281 			skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
1282 			struct page *page = sk->sk_sndmsg_page;
1283 			int off = sk->sk_sndmsg_off;
1284 			unsigned int left;
1285 
1286 			if (page && (left = PAGE_SIZE - off) > 0) {
1287 				if (copy >= left)
1288 					copy = left;
1289 				if (page != frag->page) {
1290 					if (i == MAX_SKB_FRAGS) {
1291 						err = -EMSGSIZE;
1292 						goto error;
1293 					}
1294 					get_page(page);
1295 					skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
1296 					frag = &skb_shinfo(skb)->frags[i];
1297 				}
1298 			} else if(i < MAX_SKB_FRAGS) {
1299 				if (copy > PAGE_SIZE)
1300 					copy = PAGE_SIZE;
1301 				page = alloc_pages(sk->sk_allocation, 0);
1302 				if (page == NULL) {
1303 					err = -ENOMEM;
1304 					goto error;
1305 				}
1306 				sk->sk_sndmsg_page = page;
1307 				sk->sk_sndmsg_off = 0;
1308 
1309 				skb_fill_page_desc(skb, i, page, 0, 0);
1310 				frag = &skb_shinfo(skb)->frags[i];
1311 				skb->truesize += PAGE_SIZE;
1312 				atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
1313 			} else {
1314 				err = -EMSGSIZE;
1315 				goto error;
1316 			}
1317 			if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1318 				err = -EFAULT;
1319 				goto error;
1320 			}
1321 			sk->sk_sndmsg_off += copy;
1322 			frag->size += copy;
1323 			skb->len += copy;
1324 			skb->data_len += copy;
1325 		}
1326 		offset += copy;
1327 		length -= copy;
1328 	}
1329 	return 0;
1330 error:
1331 	inet->cork.length -= length;
1332 	IP6_INC_STATS(rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
1333 	return err;
1334 }
1335 
1336 int ip6_push_pending_frames(struct sock *sk)
1337 {
1338 	struct sk_buff *skb, *tmp_skb;
1339 	struct sk_buff **tail_skb;
1340 	struct in6_addr final_dst_buf, *final_dst = &final_dst_buf;
1341 	struct inet_sock *inet = inet_sk(sk);
1342 	struct ipv6_pinfo *np = inet6_sk(sk);
1343 	struct ipv6hdr *hdr;
1344 	struct ipv6_txoptions *opt = np->cork.opt;
1345 	struct rt6_info *rt = np->cork.rt;
1346 	struct flowi *fl = &inet->cork.fl;
1347 	unsigned char proto = fl->proto;
1348 	int err = 0;
1349 
1350 	if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1351 		goto out;
1352 	tail_skb = &(skb_shinfo(skb)->frag_list);
1353 
1354 	/* move skb->data to ip header from ext header */
1355 	if (skb->data < skb_network_header(skb))
1356 		__skb_pull(skb, skb_network_offset(skb));
1357 	while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1358 		__skb_pull(tmp_skb, skb_network_header_len(skb));
1359 		*tail_skb = tmp_skb;
1360 		tail_skb = &(tmp_skb->next);
1361 		skb->len += tmp_skb->len;
1362 		skb->data_len += tmp_skb->len;
1363 		skb->truesize += tmp_skb->truesize;
1364 		__sock_put(tmp_skb->sk);
1365 		tmp_skb->destructor = NULL;
1366 		tmp_skb->sk = NULL;
1367 	}
1368 
1369 	ipv6_addr_copy(final_dst, &fl->fl6_dst);
1370 	__skb_pull(skb, skb_network_header_len(skb));
1371 	if (opt && opt->opt_flen)
1372 		ipv6_push_frag_opts(skb, opt, &proto);
1373 	if (opt && opt->opt_nflen)
1374 		ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst);
1375 
1376 	skb_push(skb, sizeof(struct ipv6hdr));
1377 	skb_reset_network_header(skb);
1378 	hdr = ipv6_hdr(skb);
1379 
1380 	*(__be32*)hdr = fl->fl6_flowlabel |
1381 		     htonl(0x60000000 | ((int)np->cork.tclass << 20));
1382 
1383 	if (skb->len <= sizeof(struct ipv6hdr) + IPV6_MAXPLEN)
1384 		hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
1385 	else
1386 		hdr->payload_len = 0;
1387 	hdr->hop_limit = np->cork.hop_limit;
1388 	hdr->nexthdr = proto;
1389 	ipv6_addr_copy(&hdr->saddr, &fl->fl6_src);
1390 	ipv6_addr_copy(&hdr->daddr, final_dst);
1391 
1392 	skb->priority = sk->sk_priority;
1393 
1394 	skb->dst = dst_clone(&rt->u.dst);
1395 	IP6_INC_STATS(rt->rt6i_idev, IPSTATS_MIB_OUTREQUESTS);
1396 	err = NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, skb->dst->dev, dst_output);
1397 	if (err) {
1398 		if (err > 0)
1399 			err = np->recverr ? net_xmit_errno(err) : 0;
1400 		if (err)
1401 			goto error;
1402 	}
1403 
1404 out:
1405 	inet->cork.flags &= ~IPCORK_OPT;
1406 	kfree(np->cork.opt);
1407 	np->cork.opt = NULL;
1408 	if (np->cork.rt) {
1409 		dst_release(&np->cork.rt->u.dst);
1410 		np->cork.rt = NULL;
1411 		inet->cork.flags &= ~IPCORK_ALLFRAG;
1412 	}
1413 	memset(&inet->cork.fl, 0, sizeof(inet->cork.fl));
1414 	return err;
1415 error:
1416 	goto out;
1417 }
1418 
1419 void ip6_flush_pending_frames(struct sock *sk)
1420 {
1421 	struct inet_sock *inet = inet_sk(sk);
1422 	struct ipv6_pinfo *np = inet6_sk(sk);
1423 	struct sk_buff *skb;
1424 
1425 	while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) {
1426 		IP6_INC_STATS(ip6_dst_idev(skb->dst),
1427 			      IPSTATS_MIB_OUTDISCARDS);
1428 		kfree_skb(skb);
1429 	}
1430 
1431 	inet->cork.flags &= ~IPCORK_OPT;
1432 
1433 	kfree(np->cork.opt);
1434 	np->cork.opt = NULL;
1435 	if (np->cork.rt) {
1436 		dst_release(&np->cork.rt->u.dst);
1437 		np->cork.rt = NULL;
1438 		inet->cork.flags &= ~IPCORK_ALLFRAG;
1439 	}
1440 	memset(&inet->cork.fl, 0, sizeof(inet->cork.fl));
1441 }
1442