xref: /linux/net/ipv6/datagram.c (revision d524dac9279b6a41ffdf7ff7958c577f2e387db6)
1 /*
2  *	common UDP/RAW code
3  *	Linux INET6 implementation
4  *
5  *	Authors:
6  *	Pedro Roque		<roque@di.fc.ul.pt>
7  *
8  *	This program is free software; you can redistribute it and/or
9  *      modify it under the terms of the GNU General Public License
10  *      as published by the Free Software Foundation; either version
11  *      2 of the License, or (at your option) any later version.
12  */
13 
14 #include <linux/capability.h>
15 #include <linux/errno.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/interrupt.h>
19 #include <linux/socket.h>
20 #include <linux/sockios.h>
21 #include <linux/in6.h>
22 #include <linux/ipv6.h>
23 #include <linux/route.h>
24 #include <linux/slab.h>
25 
26 #include <net/ipv6.h>
27 #include <net/ndisc.h>
28 #include <net/addrconf.h>
29 #include <net/transp_v6.h>
30 #include <net/ip6_route.h>
31 #include <net/tcp_states.h>
32 
33 #include <linux/errqueue.h>
34 #include <asm/uaccess.h>
35 
36 int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
37 {
38 	struct sockaddr_in6	*usin = (struct sockaddr_in6 *) uaddr;
39 	struct inet_sock      	*inet = inet_sk(sk);
40 	struct ipv6_pinfo      	*np = inet6_sk(sk);
41 	struct in6_addr		*daddr, *final_p, final;
42 	struct dst_entry	*dst;
43 	struct flowi		fl;
44 	struct ip6_flowlabel	*flowlabel = NULL;
45 	struct ipv6_txoptions   *opt;
46 	int			addr_type;
47 	int			err;
48 
49 	if (usin->sin6_family == AF_INET) {
50 		if (__ipv6_only_sock(sk))
51 			return -EAFNOSUPPORT;
52 		err = ip4_datagram_connect(sk, uaddr, addr_len);
53 		goto ipv4_connected;
54 	}
55 
56 	if (addr_len < SIN6_LEN_RFC2133)
57 		return -EINVAL;
58 
59 	if (usin->sin6_family != AF_INET6)
60 		return -EAFNOSUPPORT;
61 
62 	memset(&fl, 0, sizeof(fl));
63 	if (np->sndflow) {
64 		fl.fl6_flowlabel = usin->sin6_flowinfo&IPV6_FLOWINFO_MASK;
65 		if (fl.fl6_flowlabel&IPV6_FLOWLABEL_MASK) {
66 			flowlabel = fl6_sock_lookup(sk, fl.fl6_flowlabel);
67 			if (flowlabel == NULL)
68 				return -EINVAL;
69 			ipv6_addr_copy(&usin->sin6_addr, &flowlabel->dst);
70 		}
71 	}
72 
73 	addr_type = ipv6_addr_type(&usin->sin6_addr);
74 
75 	if (addr_type == IPV6_ADDR_ANY) {
76 		/*
77 		 *	connect to self
78 		 */
79 		usin->sin6_addr.s6_addr[15] = 0x01;
80 	}
81 
82 	daddr = &usin->sin6_addr;
83 
84 	if (addr_type == IPV6_ADDR_MAPPED) {
85 		struct sockaddr_in sin;
86 
87 		if (__ipv6_only_sock(sk)) {
88 			err = -ENETUNREACH;
89 			goto out;
90 		}
91 		sin.sin_family = AF_INET;
92 		sin.sin_addr.s_addr = daddr->s6_addr32[3];
93 		sin.sin_port = usin->sin6_port;
94 
95 		err = ip4_datagram_connect(sk,
96 					   (struct sockaddr*) &sin,
97 					   sizeof(sin));
98 
99 ipv4_connected:
100 		if (err)
101 			goto out;
102 
103 		ipv6_addr_set_v4mapped(inet->inet_daddr, &np->daddr);
104 
105 		if (ipv6_addr_any(&np->saddr))
106 			ipv6_addr_set_v4mapped(inet->inet_saddr, &np->saddr);
107 
108 		if (ipv6_addr_any(&np->rcv_saddr)) {
109 			ipv6_addr_set_v4mapped(inet->inet_rcv_saddr,
110 					       &np->rcv_saddr);
111 			if (sk->sk_prot->rehash)
112 				sk->sk_prot->rehash(sk);
113 		}
114 
115 		goto out;
116 	}
117 
118 	if (addr_type&IPV6_ADDR_LINKLOCAL) {
119 		if (addr_len >= sizeof(struct sockaddr_in6) &&
120 		    usin->sin6_scope_id) {
121 			if (sk->sk_bound_dev_if &&
122 			    sk->sk_bound_dev_if != usin->sin6_scope_id) {
123 				err = -EINVAL;
124 				goto out;
125 			}
126 			sk->sk_bound_dev_if = usin->sin6_scope_id;
127 		}
128 
129 		if (!sk->sk_bound_dev_if && (addr_type & IPV6_ADDR_MULTICAST))
130 			sk->sk_bound_dev_if = np->mcast_oif;
131 
132 		/* Connect to link-local address requires an interface */
133 		if (!sk->sk_bound_dev_if) {
134 			err = -EINVAL;
135 			goto out;
136 		}
137 	}
138 
139 	ipv6_addr_copy(&np->daddr, daddr);
140 	np->flow_label = fl.fl6_flowlabel;
141 
142 	inet->inet_dport = usin->sin6_port;
143 
144 	/*
145 	 *	Check for a route to destination an obtain the
146 	 *	destination cache for it.
147 	 */
148 
149 	fl.proto = sk->sk_protocol;
150 	ipv6_addr_copy(&fl.fl6_dst, &np->daddr);
151 	ipv6_addr_copy(&fl.fl6_src, &np->saddr);
152 	fl.oif = sk->sk_bound_dev_if;
153 	fl.mark = sk->sk_mark;
154 	fl.fl_ip_dport = inet->inet_dport;
155 	fl.fl_ip_sport = inet->inet_sport;
156 
157 	if (!fl.oif && (addr_type&IPV6_ADDR_MULTICAST))
158 		fl.oif = np->mcast_oif;
159 
160 	security_sk_classify_flow(sk, &fl);
161 
162 	opt = flowlabel ? flowlabel->opt : np->opt;
163 	final_p = fl6_update_dst(&fl, opt, &final);
164 
165 	err = ip6_dst_lookup(sk, &dst, &fl);
166 	if (err)
167 		goto out;
168 	if (final_p)
169 		ipv6_addr_copy(&fl.fl6_dst, final_p);
170 
171 	err = __xfrm_lookup(sock_net(sk), &dst, &fl, sk, XFRM_LOOKUP_WAIT);
172 	if (err < 0) {
173 		if (err == -EREMOTE)
174 			err = ip6_dst_blackhole(sk, &dst, &fl);
175 		if (err < 0)
176 			goto out;
177 	}
178 
179 	/* source address lookup done in ip6_dst_lookup */
180 
181 	if (ipv6_addr_any(&np->saddr))
182 		ipv6_addr_copy(&np->saddr, &fl.fl6_src);
183 
184 	if (ipv6_addr_any(&np->rcv_saddr)) {
185 		ipv6_addr_copy(&np->rcv_saddr, &fl.fl6_src);
186 		inet->inet_rcv_saddr = LOOPBACK4_IPV6;
187 		if (sk->sk_prot->rehash)
188 			sk->sk_prot->rehash(sk);
189 	}
190 
191 	ip6_dst_store(sk, dst,
192 		      ipv6_addr_equal(&fl.fl6_dst, &np->daddr) ?
193 		      &np->daddr : NULL,
194 #ifdef CONFIG_IPV6_SUBTREES
195 		      ipv6_addr_equal(&fl.fl6_src, &np->saddr) ?
196 		      &np->saddr :
197 #endif
198 		      NULL);
199 
200 	sk->sk_state = TCP_ESTABLISHED;
201 out:
202 	fl6_sock_release(flowlabel);
203 	return err;
204 }
205 
206 void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err,
207 		     __be16 port, u32 info, u8 *payload)
208 {
209 	struct ipv6_pinfo *np  = inet6_sk(sk);
210 	struct icmp6hdr *icmph = icmp6_hdr(skb);
211 	struct sock_exterr_skb *serr;
212 
213 	if (!np->recverr)
214 		return;
215 
216 	skb = skb_clone(skb, GFP_ATOMIC);
217 	if (!skb)
218 		return;
219 
220 	skb->protocol = htons(ETH_P_IPV6);
221 
222 	serr = SKB_EXT_ERR(skb);
223 	serr->ee.ee_errno = err;
224 	serr->ee.ee_origin = SO_EE_ORIGIN_ICMP6;
225 	serr->ee.ee_type = icmph->icmp6_type;
226 	serr->ee.ee_code = icmph->icmp6_code;
227 	serr->ee.ee_pad = 0;
228 	serr->ee.ee_info = info;
229 	serr->ee.ee_data = 0;
230 	serr->addr_offset = (u8 *)&(((struct ipv6hdr *)(icmph + 1))->daddr) -
231 				  skb_network_header(skb);
232 	serr->port = port;
233 
234 	__skb_pull(skb, payload - skb->data);
235 	skb_reset_transport_header(skb);
236 
237 	if (sock_queue_err_skb(sk, skb))
238 		kfree_skb(skb);
239 }
240 
241 void ipv6_local_error(struct sock *sk, int err, struct flowi *fl, u32 info)
242 {
243 	struct ipv6_pinfo *np = inet6_sk(sk);
244 	struct sock_exterr_skb *serr;
245 	struct ipv6hdr *iph;
246 	struct sk_buff *skb;
247 
248 	if (!np->recverr)
249 		return;
250 
251 	skb = alloc_skb(sizeof(struct ipv6hdr), GFP_ATOMIC);
252 	if (!skb)
253 		return;
254 
255 	skb->protocol = htons(ETH_P_IPV6);
256 
257 	skb_put(skb, sizeof(struct ipv6hdr));
258 	skb_reset_network_header(skb);
259 	iph = ipv6_hdr(skb);
260 	ipv6_addr_copy(&iph->daddr, &fl->fl6_dst);
261 
262 	serr = SKB_EXT_ERR(skb);
263 	serr->ee.ee_errno = err;
264 	serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
265 	serr->ee.ee_type = 0;
266 	serr->ee.ee_code = 0;
267 	serr->ee.ee_pad = 0;
268 	serr->ee.ee_info = info;
269 	serr->ee.ee_data = 0;
270 	serr->addr_offset = (u8 *)&iph->daddr - skb_network_header(skb);
271 	serr->port = fl->fl_ip_dport;
272 
273 	__skb_pull(skb, skb_tail_pointer(skb) - skb->data);
274 	skb_reset_transport_header(skb);
275 
276 	if (sock_queue_err_skb(sk, skb))
277 		kfree_skb(skb);
278 }
279 
280 void ipv6_local_rxpmtu(struct sock *sk, struct flowi *fl, u32 mtu)
281 {
282 	struct ipv6_pinfo *np = inet6_sk(sk);
283 	struct ipv6hdr *iph;
284 	struct sk_buff *skb;
285 	struct ip6_mtuinfo *mtu_info;
286 
287 	if (!np->rxopt.bits.rxpmtu)
288 		return;
289 
290 	skb = alloc_skb(sizeof(struct ipv6hdr), GFP_ATOMIC);
291 	if (!skb)
292 		return;
293 
294 	skb_put(skb, sizeof(struct ipv6hdr));
295 	skb_reset_network_header(skb);
296 	iph = ipv6_hdr(skb);
297 	ipv6_addr_copy(&iph->daddr, &fl->fl6_dst);
298 
299 	mtu_info = IP6CBMTU(skb);
300 	if (!mtu_info) {
301 		kfree_skb(skb);
302 		return;
303 	}
304 
305 	mtu_info->ip6m_mtu = mtu;
306 	mtu_info->ip6m_addr.sin6_family = AF_INET6;
307 	mtu_info->ip6m_addr.sin6_port = 0;
308 	mtu_info->ip6m_addr.sin6_flowinfo = 0;
309 	mtu_info->ip6m_addr.sin6_scope_id = fl->oif;
310 	ipv6_addr_copy(&mtu_info->ip6m_addr.sin6_addr, &ipv6_hdr(skb)->daddr);
311 
312 	__skb_pull(skb, skb_tail_pointer(skb) - skb->data);
313 	skb_reset_transport_header(skb);
314 
315 	skb = xchg(&np->rxpmtu, skb);
316 	kfree_skb(skb);
317 }
318 
319 /*
320  *	Handle MSG_ERRQUEUE
321  */
322 int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len)
323 {
324 	struct ipv6_pinfo *np = inet6_sk(sk);
325 	struct sock_exterr_skb *serr;
326 	struct sk_buff *skb, *skb2;
327 	struct sockaddr_in6 *sin;
328 	struct {
329 		struct sock_extended_err ee;
330 		struct sockaddr_in6	 offender;
331 	} errhdr;
332 	int err;
333 	int copied;
334 
335 	err = -EAGAIN;
336 	skb = skb_dequeue(&sk->sk_error_queue);
337 	if (skb == NULL)
338 		goto out;
339 
340 	copied = skb->len;
341 	if (copied > len) {
342 		msg->msg_flags |= MSG_TRUNC;
343 		copied = len;
344 	}
345 	err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
346 	if (err)
347 		goto out_free_skb;
348 
349 	sock_recv_timestamp(msg, sk, skb);
350 
351 	serr = SKB_EXT_ERR(skb);
352 
353 	sin = (struct sockaddr_in6 *)msg->msg_name;
354 	if (sin) {
355 		const unsigned char *nh = skb_network_header(skb);
356 		sin->sin6_family = AF_INET6;
357 		sin->sin6_flowinfo = 0;
358 		sin->sin6_port = serr->port;
359 		sin->sin6_scope_id = 0;
360 		if (skb->protocol == htons(ETH_P_IPV6)) {
361 			ipv6_addr_copy(&sin->sin6_addr,
362 				  (struct in6_addr *)(nh + serr->addr_offset));
363 			if (np->sndflow)
364 				sin->sin6_flowinfo =
365 					(*(__be32 *)(nh + serr->addr_offset - 24) &
366 					 IPV6_FLOWINFO_MASK);
367 			if (ipv6_addr_type(&sin->sin6_addr) & IPV6_ADDR_LINKLOCAL)
368 				sin->sin6_scope_id = IP6CB(skb)->iif;
369 		} else {
370 			ipv6_addr_set_v4mapped(*(__be32 *)(nh + serr->addr_offset),
371 					       &sin->sin6_addr);
372 		}
373 	}
374 
375 	memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
376 	sin = &errhdr.offender;
377 	sin->sin6_family = AF_UNSPEC;
378 	if (serr->ee.ee_origin != SO_EE_ORIGIN_LOCAL) {
379 		sin->sin6_family = AF_INET6;
380 		sin->sin6_flowinfo = 0;
381 		sin->sin6_scope_id = 0;
382 		if (skb->protocol == htons(ETH_P_IPV6)) {
383 			ipv6_addr_copy(&sin->sin6_addr, &ipv6_hdr(skb)->saddr);
384 			if (np->rxopt.all)
385 				datagram_recv_ctl(sk, msg, skb);
386 			if (ipv6_addr_type(&sin->sin6_addr) & IPV6_ADDR_LINKLOCAL)
387 				sin->sin6_scope_id = IP6CB(skb)->iif;
388 		} else {
389 			struct inet_sock *inet = inet_sk(sk);
390 
391 			ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr,
392 					       &sin->sin6_addr);
393 			if (inet->cmsg_flags)
394 				ip_cmsg_recv(msg, skb);
395 		}
396 	}
397 
398 	put_cmsg(msg, SOL_IPV6, IPV6_RECVERR, sizeof(errhdr), &errhdr);
399 
400 	/* Now we could try to dump offended packet options */
401 
402 	msg->msg_flags |= MSG_ERRQUEUE;
403 	err = copied;
404 
405 	/* Reset and regenerate socket error */
406 	spin_lock_bh(&sk->sk_error_queue.lock);
407 	sk->sk_err = 0;
408 	if ((skb2 = skb_peek(&sk->sk_error_queue)) != NULL) {
409 		sk->sk_err = SKB_EXT_ERR(skb2)->ee.ee_errno;
410 		spin_unlock_bh(&sk->sk_error_queue.lock);
411 		sk->sk_error_report(sk);
412 	} else {
413 		spin_unlock_bh(&sk->sk_error_queue.lock);
414 	}
415 
416 out_free_skb:
417 	kfree_skb(skb);
418 out:
419 	return err;
420 }
421 
422 /*
423  *	Handle IPV6_RECVPATHMTU
424  */
425 int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len)
426 {
427 	struct ipv6_pinfo *np = inet6_sk(sk);
428 	struct sk_buff *skb;
429 	struct sockaddr_in6 *sin;
430 	struct ip6_mtuinfo mtu_info;
431 	int err;
432 	int copied;
433 
434 	err = -EAGAIN;
435 	skb = xchg(&np->rxpmtu, NULL);
436 	if (skb == NULL)
437 		goto out;
438 
439 	copied = skb->len;
440 	if (copied > len) {
441 		msg->msg_flags |= MSG_TRUNC;
442 		copied = len;
443 	}
444 	err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
445 	if (err)
446 		goto out_free_skb;
447 
448 	sock_recv_timestamp(msg, sk, skb);
449 
450 	memcpy(&mtu_info, IP6CBMTU(skb), sizeof(mtu_info));
451 
452 	sin = (struct sockaddr_in6 *)msg->msg_name;
453 	if (sin) {
454 		sin->sin6_family = AF_INET6;
455 		sin->sin6_flowinfo = 0;
456 		sin->sin6_port = 0;
457 		sin->sin6_scope_id = mtu_info.ip6m_addr.sin6_scope_id;
458 		ipv6_addr_copy(&sin->sin6_addr, &mtu_info.ip6m_addr.sin6_addr);
459 	}
460 
461 	put_cmsg(msg, SOL_IPV6, IPV6_PATHMTU, sizeof(mtu_info), &mtu_info);
462 
463 	err = copied;
464 
465 out_free_skb:
466 	kfree_skb(skb);
467 out:
468 	return err;
469 }
470 
471 
472 int datagram_recv_ctl(struct sock *sk, struct msghdr *msg, struct sk_buff *skb)
473 {
474 	struct ipv6_pinfo *np = inet6_sk(sk);
475 	struct inet6_skb_parm *opt = IP6CB(skb);
476 	unsigned char *nh = skb_network_header(skb);
477 
478 	if (np->rxopt.bits.rxinfo) {
479 		struct in6_pktinfo src_info;
480 
481 		src_info.ipi6_ifindex = opt->iif;
482 		ipv6_addr_copy(&src_info.ipi6_addr, &ipv6_hdr(skb)->daddr);
483 		put_cmsg(msg, SOL_IPV6, IPV6_PKTINFO, sizeof(src_info), &src_info);
484 	}
485 
486 	if (np->rxopt.bits.rxhlim) {
487 		int hlim = ipv6_hdr(skb)->hop_limit;
488 		put_cmsg(msg, SOL_IPV6, IPV6_HOPLIMIT, sizeof(hlim), &hlim);
489 	}
490 
491 	if (np->rxopt.bits.rxtclass) {
492 		int tclass = (ntohl(*(__be32 *)ipv6_hdr(skb)) >> 20) & 0xff;
493 		put_cmsg(msg, SOL_IPV6, IPV6_TCLASS, sizeof(tclass), &tclass);
494 	}
495 
496 	if (np->rxopt.bits.rxflow && (*(__be32 *)nh & IPV6_FLOWINFO_MASK)) {
497 		__be32 flowinfo = *(__be32 *)nh & IPV6_FLOWINFO_MASK;
498 		put_cmsg(msg, SOL_IPV6, IPV6_FLOWINFO, sizeof(flowinfo), &flowinfo);
499 	}
500 
501 	/* HbH is allowed only once */
502 	if (np->rxopt.bits.hopopts && opt->hop) {
503 		u8 *ptr = nh + opt->hop;
504 		put_cmsg(msg, SOL_IPV6, IPV6_HOPOPTS, (ptr[1]+1)<<3, ptr);
505 	}
506 
507 	if (opt->lastopt &&
508 	    (np->rxopt.bits.dstopts || np->rxopt.bits.srcrt)) {
509 		/*
510 		 * Silly enough, but we need to reparse in order to
511 		 * report extension headers (except for HbH)
512 		 * in order.
513 		 *
514 		 * Also note that IPV6_RECVRTHDRDSTOPTS is NOT
515 		 * (and WILL NOT be) defined because
516 		 * IPV6_RECVDSTOPTS is more generic. --yoshfuji
517 		 */
518 		unsigned int off = sizeof(struct ipv6hdr);
519 		u8 nexthdr = ipv6_hdr(skb)->nexthdr;
520 
521 		while (off <= opt->lastopt) {
522 			unsigned len;
523 			u8 *ptr = nh + off;
524 
525 			switch(nexthdr) {
526 			case IPPROTO_DSTOPTS:
527 				nexthdr = ptr[0];
528 				len = (ptr[1] + 1) << 3;
529 				if (np->rxopt.bits.dstopts)
530 					put_cmsg(msg, SOL_IPV6, IPV6_DSTOPTS, len, ptr);
531 				break;
532 			case IPPROTO_ROUTING:
533 				nexthdr = ptr[0];
534 				len = (ptr[1] + 1) << 3;
535 				if (np->rxopt.bits.srcrt)
536 					put_cmsg(msg, SOL_IPV6, IPV6_RTHDR, len, ptr);
537 				break;
538 			case IPPROTO_AH:
539 				nexthdr = ptr[0];
540 				len = (ptr[1] + 2) << 2;
541 				break;
542 			default:
543 				nexthdr = ptr[0];
544 				len = (ptr[1] + 1) << 3;
545 				break;
546 			}
547 
548 			off += len;
549 		}
550 	}
551 
552 	/* socket options in old style */
553 	if (np->rxopt.bits.rxoinfo) {
554 		struct in6_pktinfo src_info;
555 
556 		src_info.ipi6_ifindex = opt->iif;
557 		ipv6_addr_copy(&src_info.ipi6_addr, &ipv6_hdr(skb)->daddr);
558 		put_cmsg(msg, SOL_IPV6, IPV6_2292PKTINFO, sizeof(src_info), &src_info);
559 	}
560 	if (np->rxopt.bits.rxohlim) {
561 		int hlim = ipv6_hdr(skb)->hop_limit;
562 		put_cmsg(msg, SOL_IPV6, IPV6_2292HOPLIMIT, sizeof(hlim), &hlim);
563 	}
564 	if (np->rxopt.bits.ohopopts && opt->hop) {
565 		u8 *ptr = nh + opt->hop;
566 		put_cmsg(msg, SOL_IPV6, IPV6_2292HOPOPTS, (ptr[1]+1)<<3, ptr);
567 	}
568 	if (np->rxopt.bits.odstopts && opt->dst0) {
569 		u8 *ptr = nh + opt->dst0;
570 		put_cmsg(msg, SOL_IPV6, IPV6_2292DSTOPTS, (ptr[1]+1)<<3, ptr);
571 	}
572 	if (np->rxopt.bits.osrcrt && opt->srcrt) {
573 		struct ipv6_rt_hdr *rthdr = (struct ipv6_rt_hdr *)(nh + opt->srcrt);
574 		put_cmsg(msg, SOL_IPV6, IPV6_2292RTHDR, (rthdr->hdrlen+1) << 3, rthdr);
575 	}
576 	if (np->rxopt.bits.odstopts && opt->dst1) {
577 		u8 *ptr = nh + opt->dst1;
578 		put_cmsg(msg, SOL_IPV6, IPV6_2292DSTOPTS, (ptr[1]+1)<<3, ptr);
579 	}
580 	if (np->rxopt.bits.rxorigdstaddr) {
581 		struct sockaddr_in6 sin6;
582 		u16 *ports = (u16 *) skb_transport_header(skb);
583 
584 		if (skb_transport_offset(skb) + 4 <= skb->len) {
585 			/* All current transport protocols have the port numbers in the
586 			 * first four bytes of the transport header and this function is
587 			 * written with this assumption in mind.
588 			 */
589 
590 			sin6.sin6_family = AF_INET6;
591 			ipv6_addr_copy(&sin6.sin6_addr, &ipv6_hdr(skb)->daddr);
592 			sin6.sin6_port = ports[1];
593 			sin6.sin6_flowinfo = 0;
594 			sin6.sin6_scope_id = 0;
595 
596 			put_cmsg(msg, SOL_IPV6, IPV6_ORIGDSTADDR, sizeof(sin6), &sin6);
597 		}
598 	}
599 	return 0;
600 }
601 
602 int datagram_send_ctl(struct net *net,
603 		      struct msghdr *msg, struct flowi *fl,
604 		      struct ipv6_txoptions *opt,
605 		      int *hlimit, int *tclass, int *dontfrag)
606 {
607 	struct in6_pktinfo *src_info;
608 	struct cmsghdr *cmsg;
609 	struct ipv6_rt_hdr *rthdr;
610 	struct ipv6_opt_hdr *hdr;
611 	int len;
612 	int err = 0;
613 
614 	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
615 		int addr_type;
616 
617 		if (!CMSG_OK(msg, cmsg)) {
618 			err = -EINVAL;
619 			goto exit_f;
620 		}
621 
622 		if (cmsg->cmsg_level != SOL_IPV6)
623 			continue;
624 
625 		switch (cmsg->cmsg_type) {
626 		case IPV6_PKTINFO:
627 		case IPV6_2292PKTINFO:
628 		    {
629 			struct net_device *dev = NULL;
630 
631 			if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct in6_pktinfo))) {
632 				err = -EINVAL;
633 				goto exit_f;
634 			}
635 
636 			src_info = (struct in6_pktinfo *)CMSG_DATA(cmsg);
637 
638 			if (src_info->ipi6_ifindex) {
639 				if (fl->oif && src_info->ipi6_ifindex != fl->oif)
640 					return -EINVAL;
641 				fl->oif = src_info->ipi6_ifindex;
642 			}
643 
644 			addr_type = __ipv6_addr_type(&src_info->ipi6_addr);
645 
646 			rcu_read_lock();
647 			if (fl->oif) {
648 				dev = dev_get_by_index_rcu(net, fl->oif);
649 				if (!dev) {
650 					rcu_read_unlock();
651 					return -ENODEV;
652 				}
653 			} else if (addr_type & IPV6_ADDR_LINKLOCAL) {
654 				rcu_read_unlock();
655 				return -EINVAL;
656 			}
657 
658 			if (addr_type != IPV6_ADDR_ANY) {
659 				int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;
660 				if (!ipv6_chk_addr(net, &src_info->ipi6_addr,
661 						   strict ? dev : NULL, 0))
662 					err = -EINVAL;
663 				else
664 					ipv6_addr_copy(&fl->fl6_src, &src_info->ipi6_addr);
665 			}
666 
667 			rcu_read_unlock();
668 
669 			if (err)
670 				goto exit_f;
671 
672 			break;
673 		    }
674 
675 		case IPV6_FLOWINFO:
676 			if (cmsg->cmsg_len < CMSG_LEN(4)) {
677 				err = -EINVAL;
678 				goto exit_f;
679 			}
680 
681 			if (fl->fl6_flowlabel&IPV6_FLOWINFO_MASK) {
682 				if ((fl->fl6_flowlabel^*(__be32 *)CMSG_DATA(cmsg))&~IPV6_FLOWINFO_MASK) {
683 					err = -EINVAL;
684 					goto exit_f;
685 				}
686 			}
687 			fl->fl6_flowlabel = IPV6_FLOWINFO_MASK & *(__be32 *)CMSG_DATA(cmsg);
688 			break;
689 
690 		case IPV6_2292HOPOPTS:
691 		case IPV6_HOPOPTS:
692 			if (opt->hopopt || cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
693 				err = -EINVAL;
694 				goto exit_f;
695 			}
696 
697 			hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
698 			len = ((hdr->hdrlen + 1) << 3);
699 			if (cmsg->cmsg_len < CMSG_LEN(len)) {
700 				err = -EINVAL;
701 				goto exit_f;
702 			}
703 			if (!capable(CAP_NET_RAW)) {
704 				err = -EPERM;
705 				goto exit_f;
706 			}
707 			opt->opt_nflen += len;
708 			opt->hopopt = hdr;
709 			break;
710 
711 		case IPV6_2292DSTOPTS:
712 			if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
713 				err = -EINVAL;
714 				goto exit_f;
715 			}
716 
717 			hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
718 			len = ((hdr->hdrlen + 1) << 3);
719 			if (cmsg->cmsg_len < CMSG_LEN(len)) {
720 				err = -EINVAL;
721 				goto exit_f;
722 			}
723 			if (!capable(CAP_NET_RAW)) {
724 				err = -EPERM;
725 				goto exit_f;
726 			}
727 			if (opt->dst1opt) {
728 				err = -EINVAL;
729 				goto exit_f;
730 			}
731 			opt->opt_flen += len;
732 			opt->dst1opt = hdr;
733 			break;
734 
735 		case IPV6_DSTOPTS:
736 		case IPV6_RTHDRDSTOPTS:
737 			if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
738 				err = -EINVAL;
739 				goto exit_f;
740 			}
741 
742 			hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
743 			len = ((hdr->hdrlen + 1) << 3);
744 			if (cmsg->cmsg_len < CMSG_LEN(len)) {
745 				err = -EINVAL;
746 				goto exit_f;
747 			}
748 			if (!capable(CAP_NET_RAW)) {
749 				err = -EPERM;
750 				goto exit_f;
751 			}
752 			if (cmsg->cmsg_type == IPV6_DSTOPTS) {
753 				opt->opt_flen += len;
754 				opt->dst1opt = hdr;
755 			} else {
756 				opt->opt_nflen += len;
757 				opt->dst0opt = hdr;
758 			}
759 			break;
760 
761 		case IPV6_2292RTHDR:
762 		case IPV6_RTHDR:
763 			if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_rt_hdr))) {
764 				err = -EINVAL;
765 				goto exit_f;
766 			}
767 
768 			rthdr = (struct ipv6_rt_hdr *)CMSG_DATA(cmsg);
769 
770 			switch (rthdr->type) {
771 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
772 			case IPV6_SRCRT_TYPE_2:
773 				if (rthdr->hdrlen != 2 ||
774 				    rthdr->segments_left != 1) {
775 					err = -EINVAL;
776 					goto exit_f;
777 				}
778 				break;
779 #endif
780 			default:
781 				err = -EINVAL;
782 				goto exit_f;
783 			}
784 
785 			len = ((rthdr->hdrlen + 1) << 3);
786 
787 			if (cmsg->cmsg_len < CMSG_LEN(len)) {
788 				err = -EINVAL;
789 				goto exit_f;
790 			}
791 
792 			/* segments left must also match */
793 			if ((rthdr->hdrlen >> 1) != rthdr->segments_left) {
794 				err = -EINVAL;
795 				goto exit_f;
796 			}
797 
798 			opt->opt_nflen += len;
799 			opt->srcrt = rthdr;
800 
801 			if (cmsg->cmsg_type == IPV6_2292RTHDR && opt->dst1opt) {
802 				int dsthdrlen = ((opt->dst1opt->hdrlen+1)<<3);
803 
804 				opt->opt_nflen += dsthdrlen;
805 				opt->dst0opt = opt->dst1opt;
806 				opt->dst1opt = NULL;
807 				opt->opt_flen -= dsthdrlen;
808 			}
809 
810 			break;
811 
812 		case IPV6_2292HOPLIMIT:
813 		case IPV6_HOPLIMIT:
814 			if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
815 				err = -EINVAL;
816 				goto exit_f;
817 			}
818 
819 			*hlimit = *(int *)CMSG_DATA(cmsg);
820 			if (*hlimit < -1 || *hlimit > 0xff) {
821 				err = -EINVAL;
822 				goto exit_f;
823 			}
824 
825 			break;
826 
827 		case IPV6_TCLASS:
828 		    {
829 			int tc;
830 
831 			err = -EINVAL;
832 			if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
833 				goto exit_f;
834 			}
835 
836 			tc = *(int *)CMSG_DATA(cmsg);
837 			if (tc < -1 || tc > 0xff)
838 				goto exit_f;
839 
840 			err = 0;
841 			*tclass = tc;
842 
843 			break;
844 		    }
845 
846 		case IPV6_DONTFRAG:
847 		    {
848 			int df;
849 
850 			err = -EINVAL;
851 			if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
852 				goto exit_f;
853 			}
854 
855 			df = *(int *)CMSG_DATA(cmsg);
856 			if (df < 0 || df > 1)
857 				goto exit_f;
858 
859 			err = 0;
860 			*dontfrag = df;
861 
862 			break;
863 		    }
864 		default:
865 			LIMIT_NETDEBUG(KERN_DEBUG "invalid cmsg type: %d\n",
866 				       cmsg->cmsg_type);
867 			err = -EINVAL;
868 			goto exit_f;
869 		}
870 	}
871 
872 exit_f:
873 	return err;
874 }
875