xref: /openbmc/linux/net/ipv6/udp.c (revision 6774def6)
1 /*
2  *	UDP over IPv6
3  *	Linux INET6 implementation
4  *
5  *	Authors:
6  *	Pedro Roque		<roque@di.fc.ul.pt>
7  *
8  *	Based on linux/ipv4/udp.c
9  *
10  *	Fixes:
11  *	Hideaki YOSHIFUJI	:	sin6_scope_id support
12  *	YOSHIFUJI Hideaki @USAGI and:	Support IPV6_V6ONLY socket option, which
13  *	Alexey Kuznetsov		allow both IPv4 and IPv6 sockets to bind
14  *					a single port at the same time.
15  *      Kazunori MIYAZAWA @USAGI:       change process style to use ip6_append_data
16  *      YOSHIFUJI Hideaki @USAGI:	convert /proc/net/udp6 to seq_file.
17  *
18  *	This program is free software; you can redistribute it and/or
19  *      modify it under the terms of the GNU General Public License
20  *      as published by the Free Software Foundation; either version
21  *      2 of the License, or (at your option) any later version.
22  */
23 
24 #include <linux/errno.h>
25 #include <linux/types.h>
26 #include <linux/socket.h>
27 #include <linux/sockios.h>
28 #include <linux/net.h>
29 #include <linux/in6.h>
30 #include <linux/netdevice.h>
31 #include <linux/if_arp.h>
32 #include <linux/ipv6.h>
33 #include <linux/icmpv6.h>
34 #include <linux/init.h>
35 #include <linux/module.h>
36 #include <linux/skbuff.h>
37 #include <linux/slab.h>
38 #include <asm/uaccess.h>
39 
40 #include <net/ndisc.h>
41 #include <net/protocol.h>
42 #include <net/transp_v6.h>
43 #include <net/ip6_route.h>
44 #include <net/raw.h>
45 #include <net/tcp_states.h>
46 #include <net/ip6_checksum.h>
47 #include <net/xfrm.h>
48 #include <net/inet6_hashtables.h>
49 #include <net/busy_poll.h>
50 
51 #include <linux/proc_fs.h>
52 #include <linux/seq_file.h>
53 #include <trace/events/skb.h>
54 #include "udp_impl.h"
55 
56 static unsigned int udp6_ehashfn(struct net *net,
57 				  const struct in6_addr *laddr,
58 				  const u16 lport,
59 				  const struct in6_addr *faddr,
60 				  const __be16 fport)
61 {
62 	static u32 udp6_ehash_secret __read_mostly;
63 	static u32 udp_ipv6_hash_secret __read_mostly;
64 
65 	u32 lhash, fhash;
66 
67 	net_get_random_once(&udp6_ehash_secret,
68 			    sizeof(udp6_ehash_secret));
69 	net_get_random_once(&udp_ipv6_hash_secret,
70 			    sizeof(udp_ipv6_hash_secret));
71 
72 	lhash = (__force u32)laddr->s6_addr32[3];
73 	fhash = __ipv6_addr_jhash(faddr, udp_ipv6_hash_secret);
74 
75 	return __inet6_ehashfn(lhash, lport, fhash, fport,
76 			       udp_ipv6_hash_secret + net_hash_mix(net));
77 }
78 
79 int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2)
80 {
81 	const struct in6_addr *sk2_rcv_saddr6 = inet6_rcv_saddr(sk2);
82 	int sk2_ipv6only = inet_v6_ipv6only(sk2);
83 	int addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr);
84 	int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
85 
86 	/* if both are mapped, treat as IPv4 */
87 	if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED)
88 		return (!sk2_ipv6only &&
89 			(!sk->sk_rcv_saddr || !sk2->sk_rcv_saddr ||
90 			  sk->sk_rcv_saddr == sk2->sk_rcv_saddr));
91 
92 	if (addr_type2 == IPV6_ADDR_ANY &&
93 	    !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
94 		return 1;
95 
96 	if (addr_type == IPV6_ADDR_ANY &&
97 	    !(ipv6_only_sock(sk) && addr_type2 == IPV6_ADDR_MAPPED))
98 		return 1;
99 
100 	if (sk2_rcv_saddr6 &&
101 	    ipv6_addr_equal(&sk->sk_v6_rcv_saddr, sk2_rcv_saddr6))
102 		return 1;
103 
104 	return 0;
105 }
106 
107 static unsigned int udp6_portaddr_hash(struct net *net,
108 				       const struct in6_addr *addr6,
109 				       unsigned int port)
110 {
111 	unsigned int hash, mix = net_hash_mix(net);
112 
113 	if (ipv6_addr_any(addr6))
114 		hash = jhash_1word(0, mix);
115 	else if (ipv6_addr_v4mapped(addr6))
116 		hash = jhash_1word((__force u32)addr6->s6_addr32[3], mix);
117 	else
118 		hash = jhash2((__force u32 *)addr6->s6_addr32, 4, mix);
119 
120 	return hash ^ port;
121 }
122 
123 
124 int udp_v6_get_port(struct sock *sk, unsigned short snum)
125 {
126 	unsigned int hash2_nulladdr =
127 		udp6_portaddr_hash(sock_net(sk), &in6addr_any, snum);
128 	unsigned int hash2_partial =
129 		udp6_portaddr_hash(sock_net(sk), &sk->sk_v6_rcv_saddr, 0);
130 
131 	/* precompute partial secondary hash */
132 	udp_sk(sk)->udp_portaddr_hash = hash2_partial;
133 	return udp_lib_get_port(sk, snum, ipv6_rcv_saddr_equal, hash2_nulladdr);
134 }
135 
136 static void udp_v6_rehash(struct sock *sk)
137 {
138 	u16 new_hash = udp6_portaddr_hash(sock_net(sk),
139 					  &sk->sk_v6_rcv_saddr,
140 					  inet_sk(sk)->inet_num);
141 
142 	udp_lib_rehash(sk, new_hash);
143 }
144 
145 static inline int compute_score(struct sock *sk, struct net *net,
146 				unsigned short hnum,
147 				const struct in6_addr *saddr, __be16 sport,
148 				const struct in6_addr *daddr, __be16 dport,
149 				int dif)
150 {
151 	int score = -1;
152 
153 	if (net_eq(sock_net(sk), net) && udp_sk(sk)->udp_port_hash == hnum &&
154 			sk->sk_family == PF_INET6) {
155 		struct inet_sock *inet = inet_sk(sk);
156 
157 		score = 0;
158 		if (inet->inet_dport) {
159 			if (inet->inet_dport != sport)
160 				return -1;
161 			score++;
162 		}
163 		if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
164 			if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
165 				return -1;
166 			score++;
167 		}
168 		if (!ipv6_addr_any(&sk->sk_v6_daddr)) {
169 			if (!ipv6_addr_equal(&sk->sk_v6_daddr, saddr))
170 				return -1;
171 			score++;
172 		}
173 		if (sk->sk_bound_dev_if) {
174 			if (sk->sk_bound_dev_if != dif)
175 				return -1;
176 			score++;
177 		}
178 	}
179 	return score;
180 }
181 
182 #define SCORE2_MAX (1 + 1 + 1)
183 static inline int compute_score2(struct sock *sk, struct net *net,
184 				const struct in6_addr *saddr, __be16 sport,
185 				const struct in6_addr *daddr, unsigned short hnum,
186 				int dif)
187 {
188 	int score = -1;
189 
190 	if (net_eq(sock_net(sk), net) && udp_sk(sk)->udp_port_hash == hnum &&
191 			sk->sk_family == PF_INET6) {
192 		struct inet_sock *inet = inet_sk(sk);
193 
194 		if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
195 			return -1;
196 		score = 0;
197 		if (inet->inet_dport) {
198 			if (inet->inet_dport != sport)
199 				return -1;
200 			score++;
201 		}
202 		if (!ipv6_addr_any(&sk->sk_v6_daddr)) {
203 			if (!ipv6_addr_equal(&sk->sk_v6_daddr, saddr))
204 				return -1;
205 			score++;
206 		}
207 		if (sk->sk_bound_dev_if) {
208 			if (sk->sk_bound_dev_if != dif)
209 				return -1;
210 			score++;
211 		}
212 	}
213 	return score;
214 }
215 
216 
217 /* called with read_rcu_lock() */
218 static struct sock *udp6_lib_lookup2(struct net *net,
219 		const struct in6_addr *saddr, __be16 sport,
220 		const struct in6_addr *daddr, unsigned int hnum, int dif,
221 		struct udp_hslot *hslot2, unsigned int slot2)
222 {
223 	struct sock *sk, *result;
224 	struct hlist_nulls_node *node;
225 	int score, badness, matches = 0, reuseport = 0;
226 	u32 hash = 0;
227 
228 begin:
229 	result = NULL;
230 	badness = -1;
231 	udp_portaddr_for_each_entry_rcu(sk, node, &hslot2->head) {
232 		score = compute_score2(sk, net, saddr, sport,
233 				      daddr, hnum, dif);
234 		if (score > badness) {
235 			result = sk;
236 			badness = score;
237 			reuseport = sk->sk_reuseport;
238 			if (reuseport) {
239 				hash = udp6_ehashfn(net, daddr, hnum,
240 						    saddr, sport);
241 				matches = 1;
242 			} else if (score == SCORE2_MAX)
243 				goto exact_match;
244 		} else if (score == badness && reuseport) {
245 			matches++;
246 			if (reciprocal_scale(hash, matches) == 0)
247 				result = sk;
248 			hash = next_pseudo_random32(hash);
249 		}
250 	}
251 	/*
252 	 * if the nulls value we got at the end of this lookup is
253 	 * not the expected one, we must restart lookup.
254 	 * We probably met an item that was moved to another chain.
255 	 */
256 	if (get_nulls_value(node) != slot2)
257 		goto begin;
258 
259 	if (result) {
260 exact_match:
261 		if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
262 			result = NULL;
263 		else if (unlikely(compute_score2(result, net, saddr, sport,
264 				  daddr, hnum, dif) < badness)) {
265 			sock_put(result);
266 			goto begin;
267 		}
268 	}
269 	return result;
270 }
271 
272 struct sock *__udp6_lib_lookup(struct net *net,
273 				      const struct in6_addr *saddr, __be16 sport,
274 				      const struct in6_addr *daddr, __be16 dport,
275 				      int dif, struct udp_table *udptable)
276 {
277 	struct sock *sk, *result;
278 	struct hlist_nulls_node *node;
279 	unsigned short hnum = ntohs(dport);
280 	unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask);
281 	struct udp_hslot *hslot2, *hslot = &udptable->hash[slot];
282 	int score, badness, matches = 0, reuseport = 0;
283 	u32 hash = 0;
284 
285 	rcu_read_lock();
286 	if (hslot->count > 10) {
287 		hash2 = udp6_portaddr_hash(net, daddr, hnum);
288 		slot2 = hash2 & udptable->mask;
289 		hslot2 = &udptable->hash2[slot2];
290 		if (hslot->count < hslot2->count)
291 			goto begin;
292 
293 		result = udp6_lib_lookup2(net, saddr, sport,
294 					  daddr, hnum, dif,
295 					  hslot2, slot2);
296 		if (!result) {
297 			hash2 = udp6_portaddr_hash(net, &in6addr_any, hnum);
298 			slot2 = hash2 & udptable->mask;
299 			hslot2 = &udptable->hash2[slot2];
300 			if (hslot->count < hslot2->count)
301 				goto begin;
302 
303 			result = udp6_lib_lookup2(net, saddr, sport,
304 						  &in6addr_any, hnum, dif,
305 						  hslot2, slot2);
306 		}
307 		rcu_read_unlock();
308 		return result;
309 	}
310 begin:
311 	result = NULL;
312 	badness = -1;
313 	sk_nulls_for_each_rcu(sk, node, &hslot->head) {
314 		score = compute_score(sk, net, hnum, saddr, sport, daddr, dport, dif);
315 		if (score > badness) {
316 			result = sk;
317 			badness = score;
318 			reuseport = sk->sk_reuseport;
319 			if (reuseport) {
320 				hash = udp6_ehashfn(net, daddr, hnum,
321 						    saddr, sport);
322 				matches = 1;
323 			}
324 		} else if (score == badness && reuseport) {
325 			matches++;
326 			if (reciprocal_scale(hash, matches) == 0)
327 				result = sk;
328 			hash = next_pseudo_random32(hash);
329 		}
330 	}
331 	/*
332 	 * if the nulls value we got at the end of this lookup is
333 	 * not the expected one, we must restart lookup.
334 	 * We probably met an item that was moved to another chain.
335 	 */
336 	if (get_nulls_value(node) != slot)
337 		goto begin;
338 
339 	if (result) {
340 		if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
341 			result = NULL;
342 		else if (unlikely(compute_score(result, net, hnum, saddr, sport,
343 					daddr, dport, dif) < badness)) {
344 			sock_put(result);
345 			goto begin;
346 		}
347 	}
348 	rcu_read_unlock();
349 	return result;
350 }
351 EXPORT_SYMBOL_GPL(__udp6_lib_lookup);
352 
353 static struct sock *__udp6_lib_lookup_skb(struct sk_buff *skb,
354 					  __be16 sport, __be16 dport,
355 					  struct udp_table *udptable)
356 {
357 	struct sock *sk;
358 	const struct ipv6hdr *iph = ipv6_hdr(skb);
359 
360 	if (unlikely(sk = skb_steal_sock(skb)))
361 		return sk;
362 	return __udp6_lib_lookup(dev_net(skb_dst(skb)->dev), &iph->saddr, sport,
363 				 &iph->daddr, dport, inet6_iif(skb),
364 				 udptable);
365 }
366 
367 struct sock *udp6_lib_lookup(struct net *net, const struct in6_addr *saddr, __be16 sport,
368 			     const struct in6_addr *daddr, __be16 dport, int dif)
369 {
370 	return __udp6_lib_lookup(net, saddr, sport, daddr, dport, dif, &udp_table);
371 }
372 EXPORT_SYMBOL_GPL(udp6_lib_lookup);
373 
374 
375 /*
376  *	This should be easy, if there is something there we
377  *	return it, otherwise we block.
378  */
379 
380 int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
381 		  struct msghdr *msg, size_t len,
382 		  int noblock, int flags, int *addr_len)
383 {
384 	struct ipv6_pinfo *np = inet6_sk(sk);
385 	struct inet_sock *inet = inet_sk(sk);
386 	struct sk_buff *skb;
387 	unsigned int ulen, copied;
388 	int peeked, off = 0;
389 	int err;
390 	int is_udplite = IS_UDPLITE(sk);
391 	int is_udp4;
392 	bool slow;
393 
394 	if (flags & MSG_ERRQUEUE)
395 		return ipv6_recv_error(sk, msg, len, addr_len);
396 
397 	if (np->rxpmtu && np->rxopt.bits.rxpmtu)
398 		return ipv6_recv_rxpmtu(sk, msg, len, addr_len);
399 
400 try_again:
401 	skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
402 				  &peeked, &off, &err);
403 	if (!skb)
404 		goto out;
405 
406 	ulen = skb->len - sizeof(struct udphdr);
407 	copied = len;
408 	if (copied > ulen)
409 		copied = ulen;
410 	else if (copied < ulen)
411 		msg->msg_flags |= MSG_TRUNC;
412 
413 	is_udp4 = (skb->protocol == htons(ETH_P_IP));
414 
415 	/*
416 	 * If checksum is needed at all, try to do it while copying the
417 	 * data.  If the data is truncated, or if we only want a partial
418 	 * coverage checksum (UDP-Lite), do it before the copy.
419 	 */
420 
421 	if (copied < ulen || UDP_SKB_CB(skb)->partial_cov) {
422 		if (udp_lib_checksum_complete(skb))
423 			goto csum_copy_err;
424 	}
425 
426 	if (skb_csum_unnecessary(skb))
427 		err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr),
428 					      msg->msg_iov, copied);
429 	else {
430 		err = skb_copy_and_csum_datagram_iovec(skb, sizeof(struct udphdr), msg->msg_iov);
431 		if (err == -EINVAL)
432 			goto csum_copy_err;
433 	}
434 	if (unlikely(err)) {
435 		trace_kfree_skb(skb, udpv6_recvmsg);
436 		if (!peeked) {
437 			atomic_inc(&sk->sk_drops);
438 			if (is_udp4)
439 				UDP_INC_STATS_USER(sock_net(sk),
440 						   UDP_MIB_INERRORS,
441 						   is_udplite);
442 			else
443 				UDP6_INC_STATS_USER(sock_net(sk),
444 						    UDP_MIB_INERRORS,
445 						    is_udplite);
446 		}
447 		goto out_free;
448 	}
449 	if (!peeked) {
450 		if (is_udp4)
451 			UDP_INC_STATS_USER(sock_net(sk),
452 					UDP_MIB_INDATAGRAMS, is_udplite);
453 		else
454 			UDP6_INC_STATS_USER(sock_net(sk),
455 					UDP_MIB_INDATAGRAMS, is_udplite);
456 	}
457 
458 	sock_recv_ts_and_drops(msg, sk, skb);
459 
460 	/* Copy the address. */
461 	if (msg->msg_name) {
462 		DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
463 		sin6->sin6_family = AF_INET6;
464 		sin6->sin6_port = udp_hdr(skb)->source;
465 		sin6->sin6_flowinfo = 0;
466 
467 		if (is_udp4) {
468 			ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr,
469 					       &sin6->sin6_addr);
470 			sin6->sin6_scope_id = 0;
471 		} else {
472 			sin6->sin6_addr = ipv6_hdr(skb)->saddr;
473 			sin6->sin6_scope_id =
474 				ipv6_iface_scope_id(&sin6->sin6_addr,
475 						    inet6_iif(skb));
476 		}
477 		*addr_len = sizeof(*sin6);
478 	}
479 
480 	if (np->rxopt.all)
481 		ip6_datagram_recv_common_ctl(sk, msg, skb);
482 
483 	if (is_udp4) {
484 		if (inet->cmsg_flags)
485 			ip_cmsg_recv(msg, skb);
486 	} else {
487 		if (np->rxopt.all)
488 			ip6_datagram_recv_specific_ctl(sk, msg, skb);
489 	}
490 
491 	err = copied;
492 	if (flags & MSG_TRUNC)
493 		err = ulen;
494 
495 out_free:
496 	skb_free_datagram_locked(sk, skb);
497 out:
498 	return err;
499 
500 csum_copy_err:
501 	slow = lock_sock_fast(sk);
502 	if (!skb_kill_datagram(sk, skb, flags)) {
503 		if (is_udp4) {
504 			UDP_INC_STATS_USER(sock_net(sk),
505 					UDP_MIB_CSUMERRORS, is_udplite);
506 			UDP_INC_STATS_USER(sock_net(sk),
507 					UDP_MIB_INERRORS, is_udplite);
508 		} else {
509 			UDP6_INC_STATS_USER(sock_net(sk),
510 					UDP_MIB_CSUMERRORS, is_udplite);
511 			UDP6_INC_STATS_USER(sock_net(sk),
512 					UDP_MIB_INERRORS, is_udplite);
513 		}
514 	}
515 	unlock_sock_fast(sk, slow);
516 
517 	if (noblock)
518 		return -EAGAIN;
519 
520 	/* starting over for a new packet */
521 	msg->msg_flags &= ~MSG_TRUNC;
522 	goto try_again;
523 }
524 
525 void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
526 		    u8 type, u8 code, int offset, __be32 info,
527 		    struct udp_table *udptable)
528 {
529 	struct ipv6_pinfo *np;
530 	const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;
531 	const struct in6_addr *saddr = &hdr->saddr;
532 	const struct in6_addr *daddr = &hdr->daddr;
533 	struct udphdr *uh = (struct udphdr *)(skb->data+offset);
534 	struct sock *sk;
535 	int err;
536 	struct net *net = dev_net(skb->dev);
537 
538 	sk = __udp6_lib_lookup(net, daddr, uh->dest,
539 			       saddr, uh->source, inet6_iif(skb), udptable);
540 	if (sk == NULL) {
541 		ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev),
542 				   ICMP6_MIB_INERRORS);
543 		return;
544 	}
545 
546 	if (type == ICMPV6_PKT_TOOBIG) {
547 		if (!ip6_sk_accept_pmtu(sk))
548 			goto out;
549 		ip6_sk_update_pmtu(skb, sk, info);
550 	}
551 	if (type == NDISC_REDIRECT) {
552 		ip6_sk_redirect(skb, sk);
553 		goto out;
554 	}
555 
556 	np = inet6_sk(sk);
557 
558 	if (!icmpv6_err_convert(type, code, &err) && !np->recverr)
559 		goto out;
560 
561 	if (sk->sk_state != TCP_ESTABLISHED && !np->recverr)
562 		goto out;
563 
564 	if (np->recverr)
565 		ipv6_icmp_error(sk, skb, err, uh->dest, ntohl(info), (u8 *)(uh+1));
566 
567 	sk->sk_err = err;
568 	sk->sk_error_report(sk);
569 out:
570 	sock_put(sk);
571 }
572 
573 static int __udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
574 {
575 	int rc;
576 
577 	if (!ipv6_addr_any(&sk->sk_v6_daddr)) {
578 		sock_rps_save_rxhash(sk, skb);
579 		sk_mark_napi_id(sk, skb);
580 	}
581 
582 	rc = sock_queue_rcv_skb(sk, skb);
583 	if (rc < 0) {
584 		int is_udplite = IS_UDPLITE(sk);
585 
586 		/* Note that an ENOMEM error is charged twice */
587 		if (rc == -ENOMEM)
588 			UDP6_INC_STATS_BH(sock_net(sk),
589 					UDP_MIB_RCVBUFERRORS, is_udplite);
590 		UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
591 		kfree_skb(skb);
592 		return -1;
593 	}
594 	return 0;
595 }
596 
597 static __inline__ void udpv6_err(struct sk_buff *skb,
598 				 struct inet6_skb_parm *opt, u8 type,
599 				 u8 code, int offset, __be32 info)
600 {
601 	__udp6_lib_err(skb, opt, type, code, offset, info, &udp_table);
602 }
603 
604 static struct static_key udpv6_encap_needed __read_mostly;
605 void udpv6_encap_enable(void)
606 {
607 	if (!static_key_enabled(&udpv6_encap_needed))
608 		static_key_slow_inc(&udpv6_encap_needed);
609 }
610 EXPORT_SYMBOL(udpv6_encap_enable);
611 
612 int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
613 {
614 	struct udp_sock *up = udp_sk(sk);
615 	int rc;
616 	int is_udplite = IS_UDPLITE(sk);
617 
618 	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
619 		goto drop;
620 
621 	if (static_key_false(&udpv6_encap_needed) && up->encap_type) {
622 		int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
623 
624 		/*
625 		 * This is an encapsulation socket so pass the skb to
626 		 * the socket's udp_encap_rcv() hook. Otherwise, just
627 		 * fall through and pass this up the UDP socket.
628 		 * up->encap_rcv() returns the following value:
629 		 * =0 if skb was successfully passed to the encap
630 		 *    handler or was discarded by it.
631 		 * >0 if skb should be passed on to UDP.
632 		 * <0 if skb should be resubmitted as proto -N
633 		 */
634 
635 		/* if we're overly short, let UDP handle it */
636 		encap_rcv = ACCESS_ONCE(up->encap_rcv);
637 		if (skb->len > sizeof(struct udphdr) && encap_rcv != NULL) {
638 			int ret;
639 
640 			/* Verify checksum before giving to encap */
641 			if (udp_lib_checksum_complete(skb))
642 				goto csum_error;
643 
644 			ret = encap_rcv(sk, skb);
645 			if (ret <= 0) {
646 				UDP_INC_STATS_BH(sock_net(sk),
647 						 UDP_MIB_INDATAGRAMS,
648 						 is_udplite);
649 				return -ret;
650 			}
651 		}
652 
653 		/* FALLTHROUGH -- it's a UDP Packet */
654 	}
655 
656 	/*
657 	 * UDP-Lite specific tests, ignored on UDP sockets (see net/ipv4/udp.c).
658 	 */
659 	if ((is_udplite & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {
660 
661 		if (up->pcrlen == 0) {          /* full coverage was set  */
662 			LIMIT_NETDEBUG(KERN_WARNING "UDPLITE6: partial coverage"
663 				" %d while full coverage %d requested\n",
664 				UDP_SKB_CB(skb)->cscov, skb->len);
665 			goto drop;
666 		}
667 		if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
668 			LIMIT_NETDEBUG(KERN_WARNING "UDPLITE6: coverage %d "
669 						    "too small, need min %d\n",
670 				       UDP_SKB_CB(skb)->cscov, up->pcrlen);
671 			goto drop;
672 		}
673 	}
674 
675 	if (rcu_access_pointer(sk->sk_filter)) {
676 		if (udp_lib_checksum_complete(skb))
677 			goto csum_error;
678 	}
679 
680 	if (sk_rcvqueues_full(sk, sk->sk_rcvbuf)) {
681 		UDP6_INC_STATS_BH(sock_net(sk),
682 				  UDP_MIB_RCVBUFERRORS, is_udplite);
683 		goto drop;
684 	}
685 
686 	skb_dst_drop(skb);
687 
688 	bh_lock_sock(sk);
689 	rc = 0;
690 	if (!sock_owned_by_user(sk))
691 		rc = __udpv6_queue_rcv_skb(sk, skb);
692 	else if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) {
693 		bh_unlock_sock(sk);
694 		goto drop;
695 	}
696 	bh_unlock_sock(sk);
697 
698 	return rc;
699 
700 csum_error:
701 	UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
702 drop:
703 	UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
704 	atomic_inc(&sk->sk_drops);
705 	kfree_skb(skb);
706 	return -1;
707 }
708 
709 static bool __udp_v6_is_mcast_sock(struct net *net, struct sock *sk,
710 				   __be16 loc_port, const struct in6_addr *loc_addr,
711 				   __be16 rmt_port, const struct in6_addr *rmt_addr,
712 				   int dif, unsigned short hnum)
713 {
714 	struct inet_sock *inet = inet_sk(sk);
715 
716 	if (!net_eq(sock_net(sk), net))
717 		return false;
718 
719 	if (udp_sk(sk)->udp_port_hash != hnum ||
720 	    sk->sk_family != PF_INET6 ||
721 	    (inet->inet_dport && inet->inet_dport != rmt_port) ||
722 	    (!ipv6_addr_any(&sk->sk_v6_daddr) &&
723 		    !ipv6_addr_equal(&sk->sk_v6_daddr, rmt_addr)) ||
724 	    (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
725 		return false;
726 	if (!inet6_mc_check(sk, loc_addr, rmt_addr))
727 		return false;
728 	return true;
729 }
730 
731 static void flush_stack(struct sock **stack, unsigned int count,
732 			struct sk_buff *skb, unsigned int final)
733 {
734 	struct sk_buff *skb1 = NULL;
735 	struct sock *sk;
736 	unsigned int i;
737 
738 	for (i = 0; i < count; i++) {
739 		sk = stack[i];
740 		if (likely(skb1 == NULL))
741 			skb1 = (i == final) ? skb : skb_clone(skb, GFP_ATOMIC);
742 		if (!skb1) {
743 			atomic_inc(&sk->sk_drops);
744 			UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_RCVBUFERRORS,
745 					  IS_UDPLITE(sk));
746 			UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS,
747 					  IS_UDPLITE(sk));
748 		}
749 
750 		if (skb1 && udpv6_queue_rcv_skb(sk, skb1) <= 0)
751 			skb1 = NULL;
752 		sock_put(sk);
753 	}
754 	if (unlikely(skb1))
755 		kfree_skb(skb1);
756 }
757 
758 static void udp6_csum_zero_error(struct sk_buff *skb)
759 {
760 	/* RFC 2460 section 8.1 says that we SHOULD log
761 	 * this error. Well, it is reasonable.
762 	 */
763 	LIMIT_NETDEBUG(KERN_INFO "IPv6: udp checksum is 0 for [%pI6c]:%u->[%pI6c]:%u\n",
764 		       &ipv6_hdr(skb)->saddr, ntohs(udp_hdr(skb)->source),
765 		       &ipv6_hdr(skb)->daddr, ntohs(udp_hdr(skb)->dest));
766 }
767 
768 /*
769  * Note: called only from the BH handler context,
770  * so we don't need to lock the hashes.
771  */
772 static int __udp6_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
773 		const struct in6_addr *saddr, const struct in6_addr *daddr,
774 		struct udp_table *udptable)
775 {
776 	struct sock *sk, *stack[256 / sizeof(struct sock *)];
777 	const struct udphdr *uh = udp_hdr(skb);
778 	struct hlist_nulls_node *node;
779 	unsigned short hnum = ntohs(uh->dest);
780 	struct udp_hslot *hslot = udp_hashslot(udptable, net, hnum);
781 	int dif = inet6_iif(skb);
782 	unsigned int count = 0, offset = offsetof(typeof(*sk), sk_nulls_node);
783 	unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10);
784 
785 	if (use_hash2) {
786 		hash2_any = udp6_portaddr_hash(net, &in6addr_any, hnum) &
787 			    udp_table.mask;
788 		hash2 = udp6_portaddr_hash(net, daddr, hnum) & udp_table.mask;
789 start_lookup:
790 		hslot = &udp_table.hash2[hash2];
791 		offset = offsetof(typeof(*sk), __sk_common.skc_portaddr_node);
792 	}
793 
794 	spin_lock(&hslot->lock);
795 	sk_nulls_for_each_entry_offset(sk, node, &hslot->head, offset) {
796 		if (__udp_v6_is_mcast_sock(net, sk,
797 					   uh->dest, daddr,
798 					   uh->source, saddr,
799 					   dif, hnum) &&
800 		    /* If zero checksum and no_check is not on for
801 		     * the socket then skip it.
802 		     */
803 		    (uh->check || udp_sk(sk)->no_check6_rx)) {
804 			if (unlikely(count == ARRAY_SIZE(stack))) {
805 				flush_stack(stack, count, skb, ~0);
806 				count = 0;
807 			}
808 			stack[count++] = sk;
809 			sock_hold(sk);
810 		}
811 	}
812 
813 	spin_unlock(&hslot->lock);
814 
815 	/* Also lookup *:port if we are using hash2 and haven't done so yet. */
816 	if (use_hash2 && hash2 != hash2_any) {
817 		hash2 = hash2_any;
818 		goto start_lookup;
819 	}
820 
821 	if (count) {
822 		flush_stack(stack, count, skb, count - 1);
823 	} else {
824 		kfree_skb(skb);
825 	}
826 	return 0;
827 }
828 
829 int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
830 		   int proto)
831 {
832 	struct net *net = dev_net(skb->dev);
833 	struct sock *sk;
834 	struct udphdr *uh;
835 	const struct in6_addr *saddr, *daddr;
836 	u32 ulen = 0;
837 
838 	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
839 		goto discard;
840 
841 	saddr = &ipv6_hdr(skb)->saddr;
842 	daddr = &ipv6_hdr(skb)->daddr;
843 	uh = udp_hdr(skb);
844 
845 	ulen = ntohs(uh->len);
846 	if (ulen > skb->len)
847 		goto short_packet;
848 
849 	if (proto == IPPROTO_UDP) {
850 		/* UDP validates ulen. */
851 
852 		/* Check for jumbo payload */
853 		if (ulen == 0)
854 			ulen = skb->len;
855 
856 		if (ulen < sizeof(*uh))
857 			goto short_packet;
858 
859 		if (ulen < skb->len) {
860 			if (pskb_trim_rcsum(skb, ulen))
861 				goto short_packet;
862 			saddr = &ipv6_hdr(skb)->saddr;
863 			daddr = &ipv6_hdr(skb)->daddr;
864 			uh = udp_hdr(skb);
865 		}
866 	}
867 
868 	if (udp6_csum_init(skb, uh, proto))
869 		goto csum_error;
870 
871 	/*
872 	 *	Multicast receive code
873 	 */
874 	if (ipv6_addr_is_multicast(daddr))
875 		return __udp6_lib_mcast_deliver(net, skb,
876 				saddr, daddr, udptable);
877 
878 	/* Unicast */
879 
880 	/*
881 	 * check socket cache ... must talk to Alan about his plans
882 	 * for sock caches... i'll skip this for now.
883 	 */
884 	sk = __udp6_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
885 	if (sk != NULL) {
886 		int ret;
887 
888 		if (!uh->check && !udp_sk(sk)->no_check6_rx) {
889 			sock_put(sk);
890 			udp6_csum_zero_error(skb);
891 			goto csum_error;
892 		}
893 
894 		if (udp_sk(sk)->convert_csum && uh->check && !IS_UDPLITE(sk))
895 			skb_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
896 						 ip6_compute_pseudo);
897 
898 		ret = udpv6_queue_rcv_skb(sk, skb);
899 		sock_put(sk);
900 
901 		/* a return value > 0 means to resubmit the input, but
902 		 * it wants the return to be -protocol, or 0
903 		 */
904 		if (ret > 0)
905 			return -ret;
906 
907 		return 0;
908 	}
909 
910 	if (!uh->check) {
911 		udp6_csum_zero_error(skb);
912 		goto csum_error;
913 	}
914 
915 	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
916 		goto discard;
917 
918 	if (udp_lib_checksum_complete(skb))
919 		goto csum_error;
920 
921 	UDP6_INC_STATS_BH(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
922 	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
923 
924 	kfree_skb(skb);
925 	return 0;
926 
927 short_packet:
928 	LIMIT_NETDEBUG(KERN_DEBUG "UDP%sv6: short packet: From [%pI6c]:%u %d/%d to [%pI6c]:%u\n",
929 		       proto == IPPROTO_UDPLITE ? "-Lite" : "",
930 		       saddr,
931 		       ntohs(uh->source),
932 		       ulen,
933 		       skb->len,
934 		       daddr,
935 		       ntohs(uh->dest));
936 	goto discard;
937 csum_error:
938 	UDP6_INC_STATS_BH(net, UDP_MIB_CSUMERRORS, proto == IPPROTO_UDPLITE);
939 discard:
940 	UDP6_INC_STATS_BH(net, UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);
941 	kfree_skb(skb);
942 	return 0;
943 }
944 
945 static __inline__ int udpv6_rcv(struct sk_buff *skb)
946 {
947 	return __udp6_lib_rcv(skb, &udp_table, IPPROTO_UDP);
948 }
949 
950 /*
951  * Throw away all pending data and cancel the corking. Socket is locked.
952  */
953 static void udp_v6_flush_pending_frames(struct sock *sk)
954 {
955 	struct udp_sock *up = udp_sk(sk);
956 
957 	if (up->pending == AF_INET)
958 		udp_flush_pending_frames(sk);
959 	else if (up->pending) {
960 		up->len = 0;
961 		up->pending = 0;
962 		ip6_flush_pending_frames(sk);
963 	}
964 }
965 
966 /**
967  *	udp6_hwcsum_outgoing  -  handle outgoing HW checksumming
968  *	@sk:	socket we are sending on
969  *	@skb:	sk_buff containing the filled-in UDP header
970  *		(checksum field must be zeroed out)
971  */
972 static void udp6_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
973 				 const struct in6_addr *saddr,
974 				 const struct in6_addr *daddr, int len)
975 {
976 	unsigned int offset;
977 	struct udphdr *uh = udp_hdr(skb);
978 	__wsum csum = 0;
979 
980 	if (skb_queue_len(&sk->sk_write_queue) == 1) {
981 		/* Only one fragment on the socket.  */
982 		skb->csum_start = skb_transport_header(skb) - skb->head;
983 		skb->csum_offset = offsetof(struct udphdr, check);
984 		uh->check = ~csum_ipv6_magic(saddr, daddr, len, IPPROTO_UDP, 0);
985 	} else {
986 		/*
987 		 * HW-checksum won't work as there are two or more
988 		 * fragments on the socket so that all csums of sk_buffs
989 		 * should be together
990 		 */
991 		offset = skb_transport_offset(skb);
992 		skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
993 
994 		skb->ip_summed = CHECKSUM_NONE;
995 
996 		skb_queue_walk(&sk->sk_write_queue, skb) {
997 			csum = csum_add(csum, skb->csum);
998 		}
999 
1000 		uh->check = csum_ipv6_magic(saddr, daddr, len, IPPROTO_UDP,
1001 					    csum);
1002 		if (uh->check == 0)
1003 			uh->check = CSUM_MANGLED_0;
1004 	}
1005 }
1006 
1007 /*
1008  *	Sending
1009  */
1010 
1011 static int udp_v6_push_pending_frames(struct sock *sk)
1012 {
1013 	struct sk_buff *skb;
1014 	struct udphdr *uh;
1015 	struct udp_sock  *up = udp_sk(sk);
1016 	struct inet_sock *inet = inet_sk(sk);
1017 	struct flowi6 *fl6;
1018 	int err = 0;
1019 	int is_udplite = IS_UDPLITE(sk);
1020 	__wsum csum = 0;
1021 
1022 	if (up->pending == AF_INET)
1023 		return udp_push_pending_frames(sk);
1024 
1025 	fl6 = &inet->cork.fl.u.ip6;
1026 
1027 	/* Grab the skbuff where UDP header space exists. */
1028 	if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
1029 		goto out;
1030 
1031 	/*
1032 	 * Create a UDP header
1033 	 */
1034 	uh = udp_hdr(skb);
1035 	uh->source = fl6->fl6_sport;
1036 	uh->dest = fl6->fl6_dport;
1037 	uh->len = htons(up->len);
1038 	uh->check = 0;
1039 
1040 	if (is_udplite)
1041 		csum = udplite_csum_outgoing(sk, skb);
1042 	else if (up->no_check6_tx) {   /* UDP csum disabled */
1043 		skb->ip_summed = CHECKSUM_NONE;
1044 		goto send;
1045 	} else if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */
1046 		udp6_hwcsum_outgoing(sk, skb, &fl6->saddr, &fl6->daddr,
1047 				     up->len);
1048 		goto send;
1049 	} else
1050 		csum = udp_csum_outgoing(sk, skb);
1051 
1052 	/* add protocol-dependent pseudo-header */
1053 	uh->check = csum_ipv6_magic(&fl6->saddr, &fl6->daddr,
1054 				    up->len, fl6->flowi6_proto, csum);
1055 	if (uh->check == 0)
1056 		uh->check = CSUM_MANGLED_0;
1057 
1058 send:
1059 	err = ip6_push_pending_frames(sk);
1060 	if (err) {
1061 		if (err == -ENOBUFS && !inet6_sk(sk)->recverr) {
1062 			UDP6_INC_STATS_USER(sock_net(sk),
1063 					    UDP_MIB_SNDBUFERRORS, is_udplite);
1064 			err = 0;
1065 		}
1066 	} else
1067 		UDP6_INC_STATS_USER(sock_net(sk),
1068 				    UDP_MIB_OUTDATAGRAMS, is_udplite);
1069 out:
1070 	up->len = 0;
1071 	up->pending = 0;
1072 	return err;
1073 }
1074 
1075 int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
1076 		  struct msghdr *msg, size_t len)
1077 {
1078 	struct ipv6_txoptions opt_space;
1079 	struct udp_sock *up = udp_sk(sk);
1080 	struct inet_sock *inet = inet_sk(sk);
1081 	struct ipv6_pinfo *np = inet6_sk(sk);
1082 	DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
1083 	struct in6_addr *daddr, *final_p, final;
1084 	struct ipv6_txoptions *opt = NULL;
1085 	struct ip6_flowlabel *flowlabel = NULL;
1086 	struct flowi6 fl6;
1087 	struct dst_entry *dst;
1088 	int addr_len = msg->msg_namelen;
1089 	int ulen = len;
1090 	int hlimit = -1;
1091 	int tclass = -1;
1092 	int dontfrag = -1;
1093 	int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
1094 	int err;
1095 	int connected = 0;
1096 	int is_udplite = IS_UDPLITE(sk);
1097 	int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
1098 
1099 	/* destination address check */
1100 	if (sin6) {
1101 		if (addr_len < offsetof(struct sockaddr, sa_data))
1102 			return -EINVAL;
1103 
1104 		switch (sin6->sin6_family) {
1105 		case AF_INET6:
1106 			if (addr_len < SIN6_LEN_RFC2133)
1107 				return -EINVAL;
1108 			daddr = &sin6->sin6_addr;
1109 			break;
1110 		case AF_INET:
1111 			goto do_udp_sendmsg;
1112 		case AF_UNSPEC:
1113 			msg->msg_name = sin6 = NULL;
1114 			msg->msg_namelen = addr_len = 0;
1115 			daddr = NULL;
1116 			break;
1117 		default:
1118 			return -EINVAL;
1119 		}
1120 	} else if (!up->pending) {
1121 		if (sk->sk_state != TCP_ESTABLISHED)
1122 			return -EDESTADDRREQ;
1123 		daddr = &sk->sk_v6_daddr;
1124 	} else
1125 		daddr = NULL;
1126 
1127 	if (daddr) {
1128 		if (ipv6_addr_v4mapped(daddr)) {
1129 			struct sockaddr_in sin;
1130 			sin.sin_family = AF_INET;
1131 			sin.sin_port = sin6 ? sin6->sin6_port : inet->inet_dport;
1132 			sin.sin_addr.s_addr = daddr->s6_addr32[3];
1133 			msg->msg_name = &sin;
1134 			msg->msg_namelen = sizeof(sin);
1135 do_udp_sendmsg:
1136 			if (__ipv6_only_sock(sk))
1137 				return -ENETUNREACH;
1138 			return udp_sendmsg(iocb, sk, msg, len);
1139 		}
1140 	}
1141 
1142 	if (up->pending == AF_INET)
1143 		return udp_sendmsg(iocb, sk, msg, len);
1144 
1145 	/* Rough check on arithmetic overflow,
1146 	   better check is made in ip6_append_data().
1147 	   */
1148 	if (len > INT_MAX - sizeof(struct udphdr))
1149 		return -EMSGSIZE;
1150 
1151 	if (up->pending) {
1152 		/*
1153 		 * There are pending frames.
1154 		 * The socket lock must be held while it's corked.
1155 		 */
1156 		lock_sock(sk);
1157 		if (likely(up->pending)) {
1158 			if (unlikely(up->pending != AF_INET6)) {
1159 				release_sock(sk);
1160 				return -EAFNOSUPPORT;
1161 			}
1162 			dst = NULL;
1163 			goto do_append_data;
1164 		}
1165 		release_sock(sk);
1166 	}
1167 	ulen += sizeof(struct udphdr);
1168 
1169 	memset(&fl6, 0, sizeof(fl6));
1170 
1171 	if (sin6) {
1172 		if (sin6->sin6_port == 0)
1173 			return -EINVAL;
1174 
1175 		fl6.fl6_dport = sin6->sin6_port;
1176 		daddr = &sin6->sin6_addr;
1177 
1178 		if (np->sndflow) {
1179 			fl6.flowlabel = sin6->sin6_flowinfo&IPV6_FLOWINFO_MASK;
1180 			if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
1181 				flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
1182 				if (flowlabel == NULL)
1183 					return -EINVAL;
1184 			}
1185 		}
1186 
1187 		/*
1188 		 * Otherwise it will be difficult to maintain
1189 		 * sk->sk_dst_cache.
1190 		 */
1191 		if (sk->sk_state == TCP_ESTABLISHED &&
1192 		    ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
1193 			daddr = &sk->sk_v6_daddr;
1194 
1195 		if (addr_len >= sizeof(struct sockaddr_in6) &&
1196 		    sin6->sin6_scope_id &&
1197 		    __ipv6_addr_needs_scope_id(__ipv6_addr_type(daddr)))
1198 			fl6.flowi6_oif = sin6->sin6_scope_id;
1199 	} else {
1200 		if (sk->sk_state != TCP_ESTABLISHED)
1201 			return -EDESTADDRREQ;
1202 
1203 		fl6.fl6_dport = inet->inet_dport;
1204 		daddr = &sk->sk_v6_daddr;
1205 		fl6.flowlabel = np->flow_label;
1206 		connected = 1;
1207 	}
1208 
1209 	if (!fl6.flowi6_oif)
1210 		fl6.flowi6_oif = sk->sk_bound_dev_if;
1211 
1212 	if (!fl6.flowi6_oif)
1213 		fl6.flowi6_oif = np->sticky_pktinfo.ipi6_ifindex;
1214 
1215 	fl6.flowi6_mark = sk->sk_mark;
1216 
1217 	if (msg->msg_controllen) {
1218 		opt = &opt_space;
1219 		memset(opt, 0, sizeof(struct ipv6_txoptions));
1220 		opt->tot_len = sizeof(*opt);
1221 
1222 		err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
1223 					    &hlimit, &tclass, &dontfrag);
1224 		if (err < 0) {
1225 			fl6_sock_release(flowlabel);
1226 			return err;
1227 		}
1228 		if ((fl6.flowlabel&IPV6_FLOWLABEL_MASK) && !flowlabel) {
1229 			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
1230 			if (flowlabel == NULL)
1231 				return -EINVAL;
1232 		}
1233 		if (!(opt->opt_nflen|opt->opt_flen))
1234 			opt = NULL;
1235 		connected = 0;
1236 	}
1237 	if (opt == NULL)
1238 		opt = np->opt;
1239 	if (flowlabel)
1240 		opt = fl6_merge_options(&opt_space, flowlabel, opt);
1241 	opt = ipv6_fixup_options(&opt_space, opt);
1242 
1243 	fl6.flowi6_proto = sk->sk_protocol;
1244 	if (!ipv6_addr_any(daddr))
1245 		fl6.daddr = *daddr;
1246 	else
1247 		fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
1248 	if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
1249 		fl6.saddr = np->saddr;
1250 	fl6.fl6_sport = inet->inet_sport;
1251 
1252 	final_p = fl6_update_dst(&fl6, opt, &final);
1253 	if (final_p)
1254 		connected = 0;
1255 
1256 	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr)) {
1257 		fl6.flowi6_oif = np->mcast_oif;
1258 		connected = 0;
1259 	} else if (!fl6.flowi6_oif)
1260 		fl6.flowi6_oif = np->ucast_oif;
1261 
1262 	security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
1263 
1264 	dst = ip6_sk_dst_lookup_flow(sk, &fl6, final_p);
1265 	if (IS_ERR(dst)) {
1266 		err = PTR_ERR(dst);
1267 		dst = NULL;
1268 		goto out;
1269 	}
1270 
1271 	if (hlimit < 0)
1272 		hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
1273 
1274 	if (tclass < 0)
1275 		tclass = np->tclass;
1276 
1277 	if (msg->msg_flags&MSG_CONFIRM)
1278 		goto do_confirm;
1279 back_from_confirm:
1280 
1281 	lock_sock(sk);
1282 	if (unlikely(up->pending)) {
1283 		/* The socket is already corked while preparing it. */
1284 		/* ... which is an evident application bug. --ANK */
1285 		release_sock(sk);
1286 
1287 		LIMIT_NETDEBUG(KERN_DEBUG "udp cork app bug 2\n");
1288 		err = -EINVAL;
1289 		goto out;
1290 	}
1291 
1292 	up->pending = AF_INET6;
1293 
1294 do_append_data:
1295 	if (dontfrag < 0)
1296 		dontfrag = np->dontfrag;
1297 	up->len += ulen;
1298 	getfrag  =  is_udplite ?  udplite_getfrag : ip_generic_getfrag;
1299 	err = ip6_append_data(sk, getfrag, msg->msg_iov, ulen,
1300 		sizeof(struct udphdr), hlimit, tclass, opt, &fl6,
1301 		(struct rt6_info *)dst,
1302 		corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags, dontfrag);
1303 	if (err)
1304 		udp_v6_flush_pending_frames(sk);
1305 	else if (!corkreq)
1306 		err = udp_v6_push_pending_frames(sk);
1307 	else if (unlikely(skb_queue_empty(&sk->sk_write_queue)))
1308 		up->pending = 0;
1309 
1310 	if (dst) {
1311 		if (connected) {
1312 			ip6_dst_store(sk, dst,
1313 				      ipv6_addr_equal(&fl6.daddr, &sk->sk_v6_daddr) ?
1314 				      &sk->sk_v6_daddr : NULL,
1315 #ifdef CONFIG_IPV6_SUBTREES
1316 				      ipv6_addr_equal(&fl6.saddr, &np->saddr) ?
1317 				      &np->saddr :
1318 #endif
1319 				      NULL);
1320 		} else {
1321 			dst_release(dst);
1322 		}
1323 		dst = NULL;
1324 	}
1325 
1326 	if (err > 0)
1327 		err = np->recverr ? net_xmit_errno(err) : 0;
1328 	release_sock(sk);
1329 out:
1330 	dst_release(dst);
1331 	fl6_sock_release(flowlabel);
1332 	if (!err)
1333 		return len;
1334 	/*
1335 	 * ENOBUFS = no kernel mem, SOCK_NOSPACE = no sndbuf space.  Reporting
1336 	 * ENOBUFS might not be good (it's not tunable per se), but otherwise
1337 	 * we don't have a good statistic (IpOutDiscards but it can be too many
1338 	 * things).  We could add another new stat but at least for now that
1339 	 * seems like overkill.
1340 	 */
1341 	if (err == -ENOBUFS || test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
1342 		UDP6_INC_STATS_USER(sock_net(sk),
1343 				UDP_MIB_SNDBUFERRORS, is_udplite);
1344 	}
1345 	return err;
1346 
1347 do_confirm:
1348 	dst_confirm(dst);
1349 	if (!(msg->msg_flags&MSG_PROBE) || len)
1350 		goto back_from_confirm;
1351 	err = 0;
1352 	goto out;
1353 }
1354 
1355 void udpv6_destroy_sock(struct sock *sk)
1356 {
1357 	struct udp_sock *up = udp_sk(sk);
1358 	lock_sock(sk);
1359 	udp_v6_flush_pending_frames(sk);
1360 	release_sock(sk);
1361 
1362 	if (static_key_false(&udpv6_encap_needed) && up->encap_type) {
1363 		void (*encap_destroy)(struct sock *sk);
1364 		encap_destroy = ACCESS_ONCE(up->encap_destroy);
1365 		if (encap_destroy)
1366 			encap_destroy(sk);
1367 	}
1368 
1369 	inet6_destroy_sock(sk);
1370 }
1371 
1372 /*
1373  *	Socket option code for UDP
1374  */
1375 int udpv6_setsockopt(struct sock *sk, int level, int optname,
1376 		     char __user *optval, unsigned int optlen)
1377 {
1378 	if (level == SOL_UDP  ||  level == SOL_UDPLITE)
1379 		return udp_lib_setsockopt(sk, level, optname, optval, optlen,
1380 					  udp_v6_push_pending_frames);
1381 	return ipv6_setsockopt(sk, level, optname, optval, optlen);
1382 }
1383 
1384 #ifdef CONFIG_COMPAT
1385 int compat_udpv6_setsockopt(struct sock *sk, int level, int optname,
1386 			    char __user *optval, unsigned int optlen)
1387 {
1388 	if (level == SOL_UDP  ||  level == SOL_UDPLITE)
1389 		return udp_lib_setsockopt(sk, level, optname, optval, optlen,
1390 					  udp_v6_push_pending_frames);
1391 	return compat_ipv6_setsockopt(sk, level, optname, optval, optlen);
1392 }
1393 #endif
1394 
1395 int udpv6_getsockopt(struct sock *sk, int level, int optname,
1396 		     char __user *optval, int __user *optlen)
1397 {
1398 	if (level == SOL_UDP  ||  level == SOL_UDPLITE)
1399 		return udp_lib_getsockopt(sk, level, optname, optval, optlen);
1400 	return ipv6_getsockopt(sk, level, optname, optval, optlen);
1401 }
1402 
1403 #ifdef CONFIG_COMPAT
1404 int compat_udpv6_getsockopt(struct sock *sk, int level, int optname,
1405 			    char __user *optval, int __user *optlen)
1406 {
1407 	if (level == SOL_UDP  ||  level == SOL_UDPLITE)
1408 		return udp_lib_getsockopt(sk, level, optname, optval, optlen);
1409 	return compat_ipv6_getsockopt(sk, level, optname, optval, optlen);
1410 }
1411 #endif
1412 
1413 static const struct inet6_protocol udpv6_protocol = {
1414 	.handler	=	udpv6_rcv,
1415 	.err_handler	=	udpv6_err,
1416 	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
1417 };
1418 
1419 /* ------------------------------------------------------------------------ */
1420 #ifdef CONFIG_PROC_FS
1421 int udp6_seq_show(struct seq_file *seq, void *v)
1422 {
1423 	if (v == SEQ_START_TOKEN) {
1424 		seq_puts(seq, IPV6_SEQ_DGRAM_HEADER);
1425 	} else {
1426 		int bucket = ((struct udp_iter_state *)seq->private)->bucket;
1427 		struct inet_sock *inet = inet_sk(v);
1428 		__u16 srcp = ntohs(inet->inet_sport);
1429 		__u16 destp = ntohs(inet->inet_dport);
1430 		ip6_dgram_sock_seq_show(seq, v, srcp, destp, bucket);
1431 	}
1432 	return 0;
1433 }
1434 
1435 static const struct file_operations udp6_afinfo_seq_fops = {
1436 	.owner    = THIS_MODULE,
1437 	.open     = udp_seq_open,
1438 	.read     = seq_read,
1439 	.llseek   = seq_lseek,
1440 	.release  = seq_release_net
1441 };
1442 
1443 static struct udp_seq_afinfo udp6_seq_afinfo = {
1444 	.name		= "udp6",
1445 	.family		= AF_INET6,
1446 	.udp_table	= &udp_table,
1447 	.seq_fops	= &udp6_afinfo_seq_fops,
1448 	.seq_ops	= {
1449 		.show		= udp6_seq_show,
1450 	},
1451 };
1452 
1453 int __net_init udp6_proc_init(struct net *net)
1454 {
1455 	return udp_proc_register(net, &udp6_seq_afinfo);
1456 }
1457 
1458 void udp6_proc_exit(struct net *net) {
1459 	udp_proc_unregister(net, &udp6_seq_afinfo);
1460 }
1461 #endif /* CONFIG_PROC_FS */
1462 
1463 void udp_v6_clear_sk(struct sock *sk, int size)
1464 {
1465 	struct inet_sock *inet = inet_sk(sk);
1466 
1467 	/* we do not want to clear pinet6 field, because of RCU lookups */
1468 	sk_prot_clear_portaddr_nulls(sk, offsetof(struct inet_sock, pinet6));
1469 
1470 	size -= offsetof(struct inet_sock, pinet6) + sizeof(inet->pinet6);
1471 	memset(&inet->pinet6 + 1, 0, size);
1472 }
1473 
1474 /* ------------------------------------------------------------------------ */
1475 
1476 struct proto udpv6_prot = {
1477 	.name		   = "UDPv6",
1478 	.owner		   = THIS_MODULE,
1479 	.close		   = udp_lib_close,
1480 	.connect	   = ip6_datagram_connect,
1481 	.disconnect	   = udp_disconnect,
1482 	.ioctl		   = udp_ioctl,
1483 	.destroy	   = udpv6_destroy_sock,
1484 	.setsockopt	   = udpv6_setsockopt,
1485 	.getsockopt	   = udpv6_getsockopt,
1486 	.sendmsg	   = udpv6_sendmsg,
1487 	.recvmsg	   = udpv6_recvmsg,
1488 	.backlog_rcv	   = __udpv6_queue_rcv_skb,
1489 	.hash		   = udp_lib_hash,
1490 	.unhash		   = udp_lib_unhash,
1491 	.rehash		   = udp_v6_rehash,
1492 	.get_port	   = udp_v6_get_port,
1493 	.memory_allocated  = &udp_memory_allocated,
1494 	.sysctl_mem	   = sysctl_udp_mem,
1495 	.sysctl_wmem	   = &sysctl_udp_wmem_min,
1496 	.sysctl_rmem	   = &sysctl_udp_rmem_min,
1497 	.obj_size	   = sizeof(struct udp6_sock),
1498 	.slab_flags	   = SLAB_DESTROY_BY_RCU,
1499 	.h.udp_table	   = &udp_table,
1500 #ifdef CONFIG_COMPAT
1501 	.compat_setsockopt = compat_udpv6_setsockopt,
1502 	.compat_getsockopt = compat_udpv6_getsockopt,
1503 #endif
1504 	.clear_sk	   = udp_v6_clear_sk,
1505 };
1506 
1507 static struct inet_protosw udpv6_protosw = {
1508 	.type =      SOCK_DGRAM,
1509 	.protocol =  IPPROTO_UDP,
1510 	.prot =      &udpv6_prot,
1511 	.ops =       &inet6_dgram_ops,
1512 	.flags =     INET_PROTOSW_PERMANENT,
1513 };
1514 
1515 
1516 int __init udpv6_init(void)
1517 {
1518 	int ret;
1519 
1520 	ret = inet6_add_protocol(&udpv6_protocol, IPPROTO_UDP);
1521 	if (ret)
1522 		goto out;
1523 
1524 	ret = inet6_register_protosw(&udpv6_protosw);
1525 	if (ret)
1526 		goto out_udpv6_protocol;
1527 out:
1528 	return ret;
1529 
1530 out_udpv6_protocol:
1531 	inet6_del_protocol(&udpv6_protocol, IPPROTO_UDP);
1532 	goto out;
1533 }
1534 
1535 void udpv6_exit(void)
1536 {
1537 	inet6_unregister_protosw(&udpv6_protosw);
1538 	inet6_del_protocol(&udpv6_protocol, IPPROTO_UDP);
1539 }
1540