xref: /openbmc/linux/net/ipv4/af_inet.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		PF_INET protocol family socket handler.
7  *
8  * Version:	$Id: af_inet.c,v 1.137 2002/02/01 22:01:03 davem Exp $
9  *
10  * Authors:	Ross Biro
11  *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12  *		Florian La Roche, <flla@stud.uni-sb.de>
13  *		Alan Cox, <A.Cox@swansea.ac.uk>
14  *
15  * Changes (see also sock.c)
16  *
17  *		piggy,
18  *		Karl Knutson	:	Socket protocol table
19  *		A.N.Kuznetsov	:	Socket death error in accept().
20  *		John Richardson :	Fix non blocking error in connect()
21  *					so sockets that fail to connect
22  *					don't return -EINPROGRESS.
23  *		Alan Cox	:	Asynchronous I/O support
24  *		Alan Cox	:	Keep correct socket pointer on sock
25  *					structures
26  *					when accept() ed
27  *		Alan Cox	:	Semantics of SO_LINGER aren't state
28  *					moved to close when you look carefully.
29  *					With this fixed and the accept bug fixed
30  *					some RPC stuff seems happier.
31  *		Niibe Yutaka	:	4.4BSD style write async I/O
32  *		Alan Cox,
33  *		Tony Gale 	:	Fixed reuse semantics.
34  *		Alan Cox	:	bind() shouldn't abort existing but dead
35  *					sockets. Stops FTP netin:.. I hope.
36  *		Alan Cox	:	bind() works correctly for RAW sockets.
37  *					Note that FreeBSD at least was broken
38  *					in this respect so be careful with
39  *					compatibility tests...
40  *		Alan Cox	:	routing cache support
41  *		Alan Cox	:	memzero the socket structure for
42  *					compactness.
43  *		Matt Day	:	nonblock connect error handler
44  *		Alan Cox	:	Allow large numbers of pending sockets
45  *					(eg for big web sites), but only if
46  *					specifically application requested.
47  *		Alan Cox	:	New buffering throughout IP. Used
48  *					dumbly.
49  *		Alan Cox	:	New buffering now used smartly.
50  *		Alan Cox	:	BSD rather than common sense
51  *					interpretation of listen.
52  *		Germano Caronni	:	Assorted small races.
53  *		Alan Cox	:	sendmsg/recvmsg basic support.
54  *		Alan Cox	:	Only sendmsg/recvmsg now supported.
55  *		Alan Cox	:	Locked down bind (see security list).
56  *		Alan Cox	:	Loosened bind a little.
57  *		Mike McLagan	:	ADD/DEL DLCI Ioctls
58  *	Willy Konynenberg	:	Transparent proxying support.
59  *		David S. Miller	:	New socket lookup architecture.
60  *					Some other random speedups.
61  *		Cyrus Durgin	:	Cleaned up file for kmod hacks.
62  *		Andi Kleen	:	Fix inet_stream_connect TCP race.
63  *
64  *		This program is free software; you can redistribute it and/or
65  *		modify it under the terms of the GNU General Public License
66  *		as published by the Free Software Foundation; either version
67  *		2 of the License, or (at your option) any later version.
68  */
69 
70 #include <linux/config.h>
71 #include <linux/errno.h>
72 #include <linux/types.h>
73 #include <linux/socket.h>
74 #include <linux/in.h>
75 #include <linux/kernel.h>
76 #include <linux/module.h>
77 #include <linux/sched.h>
78 #include <linux/timer.h>
79 #include <linux/string.h>
80 #include <linux/sockios.h>
81 #include <linux/net.h>
82 #include <linux/fcntl.h>
83 #include <linux/mm.h>
84 #include <linux/interrupt.h>
85 #include <linux/stat.h>
86 #include <linux/init.h>
87 #include <linux/poll.h>
88 #include <linux/netfilter_ipv4.h>
89 
90 #include <asm/uaccess.h>
91 #include <asm/system.h>
92 
93 #include <linux/smp_lock.h>
94 #include <linux/inet.h>
95 #include <linux/igmp.h>
96 #include <linux/netdevice.h>
97 #include <net/ip.h>
98 #include <net/protocol.h>
99 #include <net/arp.h>
100 #include <net/route.h>
101 #include <net/ip_fib.h>
102 #include <net/inet_connection_sock.h>
103 #include <net/tcp.h>
104 #include <net/udp.h>
105 #include <linux/skbuff.h>
106 #include <net/sock.h>
107 #include <net/raw.h>
108 #include <net/icmp.h>
109 #include <net/ipip.h>
110 #include <net/inet_common.h>
111 #include <net/xfrm.h>
112 #ifdef CONFIG_IP_MROUTE
113 #include <linux/mroute.h>
114 #endif
115 
116 DEFINE_SNMP_STAT(struct linux_mib, net_statistics) __read_mostly;
117 
118 extern void ip_mc_drop_socket(struct sock *sk);
119 
120 /* The inetsw table contains everything that inet_create needs to
121  * build a new socket.
122  */
123 static struct list_head inetsw[SOCK_MAX];
124 static DEFINE_SPINLOCK(inetsw_lock);
125 
126 /* New destruction routine */
127 
128 void inet_sock_destruct(struct sock *sk)
129 {
130 	struct inet_sock *inet = inet_sk(sk);
131 
132 	__skb_queue_purge(&sk->sk_receive_queue);
133 	__skb_queue_purge(&sk->sk_error_queue);
134 
135 	if (sk->sk_type == SOCK_STREAM && sk->sk_state != TCP_CLOSE) {
136 		printk("Attempt to release TCP socket in state %d %p\n",
137 		       sk->sk_state, sk);
138 		return;
139 	}
140 	if (!sock_flag(sk, SOCK_DEAD)) {
141 		printk("Attempt to release alive inet socket %p\n", sk);
142 		return;
143 	}
144 
145 	BUG_TRAP(!atomic_read(&sk->sk_rmem_alloc));
146 	BUG_TRAP(!atomic_read(&sk->sk_wmem_alloc));
147 	BUG_TRAP(!sk->sk_wmem_queued);
148 	BUG_TRAP(!sk->sk_forward_alloc);
149 
150 	if (inet->opt)
151 		kfree(inet->opt);
152 	dst_release(sk->sk_dst_cache);
153 	sk_refcnt_debug_dec(sk);
154 }
155 
156 /*
157  *	The routines beyond this point handle the behaviour of an AF_INET
158  *	socket object. Mostly it punts to the subprotocols of IP to do
159  *	the work.
160  */
161 
162 /*
163  *	Automatically bind an unbound socket.
164  */
165 
166 static int inet_autobind(struct sock *sk)
167 {
168 	struct inet_sock *inet;
169 	/* We may need to bind the socket. */
170 	lock_sock(sk);
171 	inet = inet_sk(sk);
172 	if (!inet->num) {
173 		if (sk->sk_prot->get_port(sk, 0)) {
174 			release_sock(sk);
175 			return -EAGAIN;
176 		}
177 		inet->sport = htons(inet->num);
178 	}
179 	release_sock(sk);
180 	return 0;
181 }
182 
183 /*
184  *	Move a socket into listening state.
185  */
186 int inet_listen(struct socket *sock, int backlog)
187 {
188 	struct sock *sk = sock->sk;
189 	unsigned char old_state;
190 	int err;
191 
192 	lock_sock(sk);
193 
194 	err = -EINVAL;
195 	if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
196 		goto out;
197 
198 	old_state = sk->sk_state;
199 	if (!((1 << old_state) & (TCPF_CLOSE | TCPF_LISTEN)))
200 		goto out;
201 
202 	/* Really, if the socket is already in listen state
203 	 * we can only allow the backlog to be adjusted.
204 	 */
205 	if (old_state != TCP_LISTEN) {
206 		err = inet_csk_listen_start(sk, TCP_SYNQ_HSIZE);
207 		if (err)
208 			goto out;
209 	}
210 	sk->sk_max_ack_backlog = backlog;
211 	err = 0;
212 
213 out:
214 	release_sock(sk);
215 	return err;
216 }
217 
218 /*
219  *	Create an inet socket.
220  */
221 
222 static int inet_create(struct socket *sock, int protocol)
223 {
224 	struct sock *sk;
225 	struct list_head *p;
226 	struct inet_protosw *answer;
227 	struct inet_sock *inet;
228 	struct proto *answer_prot;
229 	unsigned char answer_flags;
230 	char answer_no_check;
231 	int try_loading_module = 0;
232 	int err = -ESOCKTNOSUPPORT;
233 
234 	sock->state = SS_UNCONNECTED;
235 
236 	/* Look for the requested type/protocol pair. */
237 	answer = NULL;
238 lookup_protocol:
239 	rcu_read_lock();
240 	list_for_each_rcu(p, &inetsw[sock->type]) {
241 		answer = list_entry(p, struct inet_protosw, list);
242 
243 		/* Check the non-wild match. */
244 		if (protocol == answer->protocol) {
245 			if (protocol != IPPROTO_IP)
246 				break;
247 		} else {
248 			/* Check for the two wild cases. */
249 			if (IPPROTO_IP == protocol) {
250 				protocol = answer->protocol;
251 				break;
252 			}
253 			if (IPPROTO_IP == answer->protocol)
254 				break;
255 		}
256 		answer = NULL;
257 	}
258 
259 	if (unlikely(answer == NULL)) {
260 		if (try_loading_module < 2) {
261 			rcu_read_unlock();
262 			/*
263 			 * Be more specific, e.g. net-pf-2-proto-132-type-1
264 			 * (net-pf-PF_INET-proto-IPPROTO_SCTP-type-SOCK_STREAM)
265 			 */
266 			if (++try_loading_module == 1)
267 				request_module("net-pf-%d-proto-%d-type-%d",
268 					       PF_INET, protocol, sock->type);
269 			/*
270 			 * Fall back to generic, e.g. net-pf-2-proto-132
271 			 * (net-pf-PF_INET-proto-IPPROTO_SCTP)
272 			 */
273 			else
274 				request_module("net-pf-%d-proto-%d",
275 					       PF_INET, protocol);
276 			goto lookup_protocol;
277 		} else
278 			goto out_rcu_unlock;
279 	}
280 
281 	err = -EPERM;
282 	if (answer->capability > 0 && !capable(answer->capability))
283 		goto out_rcu_unlock;
284 	err = -EPROTONOSUPPORT;
285 	if (!protocol)
286 		goto out_rcu_unlock;
287 
288 	sock->ops = answer->ops;
289 	answer_prot = answer->prot;
290 	answer_no_check = answer->no_check;
291 	answer_flags = answer->flags;
292 	rcu_read_unlock();
293 
294 	BUG_TRAP(answer_prot->slab != NULL);
295 
296 	err = -ENOBUFS;
297 	sk = sk_alloc(PF_INET, GFP_KERNEL, answer_prot, 1);
298 	if (sk == NULL)
299 		goto out;
300 
301 	err = 0;
302 	sk->sk_no_check = answer_no_check;
303 	if (INET_PROTOSW_REUSE & answer_flags)
304 		sk->sk_reuse = 1;
305 
306 	inet = inet_sk(sk);
307 
308 	if (SOCK_RAW == sock->type) {
309 		inet->num = protocol;
310 		if (IPPROTO_RAW == protocol)
311 			inet->hdrincl = 1;
312 	}
313 
314 	if (ipv4_config.no_pmtu_disc)
315 		inet->pmtudisc = IP_PMTUDISC_DONT;
316 	else
317 		inet->pmtudisc = IP_PMTUDISC_WANT;
318 
319 	inet->id = 0;
320 
321 	sock_init_data(sock, sk);
322 
323 	sk->sk_destruct	   = inet_sock_destruct;
324 	sk->sk_family	   = PF_INET;
325 	sk->sk_protocol	   = protocol;
326 	sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
327 
328 	inet->uc_ttl	= -1;
329 	inet->mc_loop	= 1;
330 	inet->mc_ttl	= 1;
331 	inet->mc_index	= 0;
332 	inet->mc_list	= NULL;
333 
334 	sk_refcnt_debug_inc(sk);
335 
336 	if (inet->num) {
337 		/* It assumes that any protocol which allows
338 		 * the user to assign a number at socket
339 		 * creation time automatically
340 		 * shares.
341 		 */
342 		inet->sport = htons(inet->num);
343 		/* Add to protocol hash chains. */
344 		sk->sk_prot->hash(sk);
345 	}
346 
347 	if (sk->sk_prot->init) {
348 		err = sk->sk_prot->init(sk);
349 		if (err)
350 			sk_common_release(sk);
351 	}
352 out:
353 	return err;
354 out_rcu_unlock:
355 	rcu_read_unlock();
356 	goto out;
357 }
358 
359 
360 /*
361  *	The peer socket should always be NULL (or else). When we call this
362  *	function we are destroying the object and from then on nobody
363  *	should refer to it.
364  */
365 int inet_release(struct socket *sock)
366 {
367 	struct sock *sk = sock->sk;
368 
369 	if (sk) {
370 		long timeout;
371 
372 		/* Applications forget to leave groups before exiting */
373 		ip_mc_drop_socket(sk);
374 
375 		/* If linger is set, we don't return until the close
376 		 * is complete.  Otherwise we return immediately. The
377 		 * actually closing is done the same either way.
378 		 *
379 		 * If the close is due to the process exiting, we never
380 		 * linger..
381 		 */
382 		timeout = 0;
383 		if (sock_flag(sk, SOCK_LINGER) &&
384 		    !(current->flags & PF_EXITING))
385 			timeout = sk->sk_lingertime;
386 		sock->sk = NULL;
387 		sk->sk_prot->close(sk, timeout);
388 	}
389 	return 0;
390 }
391 
392 /* It is off by default, see below. */
393 int sysctl_ip_nonlocal_bind;
394 
395 int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
396 {
397 	struct sockaddr_in *addr = (struct sockaddr_in *)uaddr;
398 	struct sock *sk = sock->sk;
399 	struct inet_sock *inet = inet_sk(sk);
400 	unsigned short snum;
401 	int chk_addr_ret;
402 	int err;
403 
404 	/* If the socket has its own bind function then use it. (RAW) */
405 	if (sk->sk_prot->bind) {
406 		err = sk->sk_prot->bind(sk, uaddr, addr_len);
407 		goto out;
408 	}
409 	err = -EINVAL;
410 	if (addr_len < sizeof(struct sockaddr_in))
411 		goto out;
412 
413 	chk_addr_ret = inet_addr_type(addr->sin_addr.s_addr);
414 
415 	/* Not specified by any standard per-se, however it breaks too
416 	 * many applications when removed.  It is unfortunate since
417 	 * allowing applications to make a non-local bind solves
418 	 * several problems with systems using dynamic addressing.
419 	 * (ie. your servers still start up even if your ISDN link
420 	 *  is temporarily down)
421 	 */
422 	err = -EADDRNOTAVAIL;
423 	if (!sysctl_ip_nonlocal_bind &&
424 	    !inet->freebind &&
425 	    addr->sin_addr.s_addr != INADDR_ANY &&
426 	    chk_addr_ret != RTN_LOCAL &&
427 	    chk_addr_ret != RTN_MULTICAST &&
428 	    chk_addr_ret != RTN_BROADCAST)
429 		goto out;
430 
431 	snum = ntohs(addr->sin_port);
432 	err = -EACCES;
433 	if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
434 		goto out;
435 
436 	/*      We keep a pair of addresses. rcv_saddr is the one
437 	 *      used by hash lookups, and saddr is used for transmit.
438 	 *
439 	 *      In the BSD API these are the same except where it
440 	 *      would be illegal to use them (multicast/broadcast) in
441 	 *      which case the sending device address is used.
442 	 */
443 	lock_sock(sk);
444 
445 	/* Check these errors (active socket, double bind). */
446 	err = -EINVAL;
447 	if (sk->sk_state != TCP_CLOSE || inet->num)
448 		goto out_release_sock;
449 
450 	inet->rcv_saddr = inet->saddr = addr->sin_addr.s_addr;
451 	if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
452 		inet->saddr = 0;  /* Use device */
453 
454 	/* Make sure we are allowed to bind here. */
455 	if (sk->sk_prot->get_port(sk, snum)) {
456 		inet->saddr = inet->rcv_saddr = 0;
457 		err = -EADDRINUSE;
458 		goto out_release_sock;
459 	}
460 
461 	if (inet->rcv_saddr)
462 		sk->sk_userlocks |= SOCK_BINDADDR_LOCK;
463 	if (snum)
464 		sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
465 	inet->sport = htons(inet->num);
466 	inet->daddr = 0;
467 	inet->dport = 0;
468 	sk_dst_reset(sk);
469 	err = 0;
470 out_release_sock:
471 	release_sock(sk);
472 out:
473 	return err;
474 }
475 
476 int inet_dgram_connect(struct socket *sock, struct sockaddr * uaddr,
477 		       int addr_len, int flags)
478 {
479 	struct sock *sk = sock->sk;
480 
481 	if (uaddr->sa_family == AF_UNSPEC)
482 		return sk->sk_prot->disconnect(sk, flags);
483 
484 	if (!inet_sk(sk)->num && inet_autobind(sk))
485 		return -EAGAIN;
486 	return sk->sk_prot->connect(sk, (struct sockaddr *)uaddr, addr_len);
487 }
488 
489 static long inet_wait_for_connect(struct sock *sk, long timeo)
490 {
491 	DEFINE_WAIT(wait);
492 
493 	prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
494 
495 	/* Basic assumption: if someone sets sk->sk_err, he _must_
496 	 * change state of the socket from TCP_SYN_*.
497 	 * Connect() does not allow to get error notifications
498 	 * without closing the socket.
499 	 */
500 	while ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
501 		release_sock(sk);
502 		timeo = schedule_timeout(timeo);
503 		lock_sock(sk);
504 		if (signal_pending(current) || !timeo)
505 			break;
506 		prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
507 	}
508 	finish_wait(sk->sk_sleep, &wait);
509 	return timeo;
510 }
511 
512 /*
513  *	Connect to a remote host. There is regrettably still a little
514  *	TCP 'magic' in here.
515  */
516 int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
517 			int addr_len, int flags)
518 {
519 	struct sock *sk = sock->sk;
520 	int err;
521 	long timeo;
522 
523 	lock_sock(sk);
524 
525 	if (uaddr->sa_family == AF_UNSPEC) {
526 		err = sk->sk_prot->disconnect(sk, flags);
527 		sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
528 		goto out;
529 	}
530 
531 	switch (sock->state) {
532 	default:
533 		err = -EINVAL;
534 		goto out;
535 	case SS_CONNECTED:
536 		err = -EISCONN;
537 		goto out;
538 	case SS_CONNECTING:
539 		err = -EALREADY;
540 		/* Fall out of switch with err, set for this state */
541 		break;
542 	case SS_UNCONNECTED:
543 		err = -EISCONN;
544 		if (sk->sk_state != TCP_CLOSE)
545 			goto out;
546 
547 		err = sk->sk_prot->connect(sk, uaddr, addr_len);
548 		if (err < 0)
549 			goto out;
550 
551   		sock->state = SS_CONNECTING;
552 
553 		/* Just entered SS_CONNECTING state; the only
554 		 * difference is that return value in non-blocking
555 		 * case is EINPROGRESS, rather than EALREADY.
556 		 */
557 		err = -EINPROGRESS;
558 		break;
559 	}
560 
561 	timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
562 
563 	if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
564 		/* Error code is set above */
565 		if (!timeo || !inet_wait_for_connect(sk, timeo))
566 			goto out;
567 
568 		err = sock_intr_errno(timeo);
569 		if (signal_pending(current))
570 			goto out;
571 	}
572 
573 	/* Connection was closed by RST, timeout, ICMP error
574 	 * or another process disconnected us.
575 	 */
576 	if (sk->sk_state == TCP_CLOSE)
577 		goto sock_error;
578 
579 	/* sk->sk_err may be not zero now, if RECVERR was ordered by user
580 	 * and error was received after socket entered established state.
581 	 * Hence, it is handled normally after connect() return successfully.
582 	 */
583 
584 	sock->state = SS_CONNECTED;
585 	err = 0;
586 out:
587 	release_sock(sk);
588 	return err;
589 
590 sock_error:
591 	err = sock_error(sk) ? : -ECONNABORTED;
592 	sock->state = SS_UNCONNECTED;
593 	if (sk->sk_prot->disconnect(sk, flags))
594 		sock->state = SS_DISCONNECTING;
595 	goto out;
596 }
597 
598 /*
599  *	Accept a pending connection. The TCP layer now gives BSD semantics.
600  */
601 
602 int inet_accept(struct socket *sock, struct socket *newsock, int flags)
603 {
604 	struct sock *sk1 = sock->sk;
605 	int err = -EINVAL;
606 	struct sock *sk2 = sk1->sk_prot->accept(sk1, flags, &err);
607 
608 	if (!sk2)
609 		goto do_err;
610 
611 	lock_sock(sk2);
612 
613 	BUG_TRAP((1 << sk2->sk_state) &
614 		 (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_CLOSE));
615 
616 	sock_graft(sk2, newsock);
617 
618 	newsock->state = SS_CONNECTED;
619 	err = 0;
620 	release_sock(sk2);
621 do_err:
622 	return err;
623 }
624 
625 
626 /*
627  *	This does both peername and sockname.
628  */
629 int inet_getname(struct socket *sock, struct sockaddr *uaddr,
630 			int *uaddr_len, int peer)
631 {
632 	struct sock *sk		= sock->sk;
633 	struct inet_sock *inet	= inet_sk(sk);
634 	struct sockaddr_in *sin	= (struct sockaddr_in *)uaddr;
635 
636 	sin->sin_family = AF_INET;
637 	if (peer) {
638 		if (!inet->dport ||
639 		    (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)) &&
640 		     peer == 1))
641 			return -ENOTCONN;
642 		sin->sin_port = inet->dport;
643 		sin->sin_addr.s_addr = inet->daddr;
644 	} else {
645 		__u32 addr = inet->rcv_saddr;
646 		if (!addr)
647 			addr = inet->saddr;
648 		sin->sin_port = inet->sport;
649 		sin->sin_addr.s_addr = addr;
650 	}
651 	memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
652 	*uaddr_len = sizeof(*sin);
653 	return 0;
654 }
655 
656 int inet_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
657 		 size_t size)
658 {
659 	struct sock *sk = sock->sk;
660 
661 	/* We may need to bind the socket. */
662 	if (!inet_sk(sk)->num && inet_autobind(sk))
663 		return -EAGAIN;
664 
665 	return sk->sk_prot->sendmsg(iocb, sk, msg, size);
666 }
667 
668 
669 static ssize_t inet_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags)
670 {
671 	struct sock *sk = sock->sk;
672 
673 	/* We may need to bind the socket. */
674 	if (!inet_sk(sk)->num && inet_autobind(sk))
675 		return -EAGAIN;
676 
677 	if (sk->sk_prot->sendpage)
678 		return sk->sk_prot->sendpage(sk, page, offset, size, flags);
679 	return sock_no_sendpage(sock, page, offset, size, flags);
680 }
681 
682 
683 int inet_shutdown(struct socket *sock, int how)
684 {
685 	struct sock *sk = sock->sk;
686 	int err = 0;
687 
688 	/* This should really check to make sure
689 	 * the socket is a TCP socket. (WHY AC...)
690 	 */
691 	how++; /* maps 0->1 has the advantage of making bit 1 rcvs and
692 		       1->2 bit 2 snds.
693 		       2->3 */
694 	if ((how & ~SHUTDOWN_MASK) || !how)	/* MAXINT->0 */
695 		return -EINVAL;
696 
697 	lock_sock(sk);
698 	if (sock->state == SS_CONNECTING) {
699 		if ((1 << sk->sk_state) &
700 		    (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE))
701 			sock->state = SS_DISCONNECTING;
702 		else
703 			sock->state = SS_CONNECTED;
704 	}
705 
706 	switch (sk->sk_state) {
707 	case TCP_CLOSE:
708 		err = -ENOTCONN;
709 		/* Hack to wake up other listeners, who can poll for
710 		   POLLHUP, even on eg. unconnected UDP sockets -- RR */
711 	default:
712 		sk->sk_shutdown |= how;
713 		if (sk->sk_prot->shutdown)
714 			sk->sk_prot->shutdown(sk, how);
715 		break;
716 
717 	/* Remaining two branches are temporary solution for missing
718 	 * close() in multithreaded environment. It is _not_ a good idea,
719 	 * but we have no choice until close() is repaired at VFS level.
720 	 */
721 	case TCP_LISTEN:
722 		if (!(how & RCV_SHUTDOWN))
723 			break;
724 		/* Fall through */
725 	case TCP_SYN_SENT:
726 		err = sk->sk_prot->disconnect(sk, O_NONBLOCK);
727 		sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
728 		break;
729 	}
730 
731 	/* Wake up anyone sleeping in poll. */
732 	sk->sk_state_change(sk);
733 	release_sock(sk);
734 	return err;
735 }
736 
737 /*
738  *	ioctl() calls you can issue on an INET socket. Most of these are
739  *	device configuration and stuff and very rarely used. Some ioctls
740  *	pass on to the socket itself.
741  *
742  *	NOTE: I like the idea of a module for the config stuff. ie ifconfig
743  *	loads the devconfigure module does its configuring and unloads it.
744  *	There's a good 20K of config code hanging around the kernel.
745  */
746 
747 int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
748 {
749 	struct sock *sk = sock->sk;
750 	int err = 0;
751 
752 	switch (cmd) {
753 		case SIOCGSTAMP:
754 			err = sock_get_timestamp(sk, (struct timeval __user *)arg);
755 			break;
756 		case SIOCADDRT:
757 		case SIOCDELRT:
758 		case SIOCRTMSG:
759 			err = ip_rt_ioctl(cmd, (void __user *)arg);
760 			break;
761 		case SIOCDARP:
762 		case SIOCGARP:
763 		case SIOCSARP:
764 			err = arp_ioctl(cmd, (void __user *)arg);
765 			break;
766 		case SIOCGIFADDR:
767 		case SIOCSIFADDR:
768 		case SIOCGIFBRDADDR:
769 		case SIOCSIFBRDADDR:
770 		case SIOCGIFNETMASK:
771 		case SIOCSIFNETMASK:
772 		case SIOCGIFDSTADDR:
773 		case SIOCSIFDSTADDR:
774 		case SIOCSIFPFLAGS:
775 		case SIOCGIFPFLAGS:
776 		case SIOCSIFFLAGS:
777 			err = devinet_ioctl(cmd, (void __user *)arg);
778 			break;
779 		default:
780 			if (!sk->sk_prot->ioctl ||
781 			    (err = sk->sk_prot->ioctl(sk, cmd, arg)) ==
782 			    					-ENOIOCTLCMD)
783 				err = dev_ioctl(cmd, (void __user *)arg);
784 			break;
785 	}
786 	return err;
787 }
788 
789 struct proto_ops inet_stream_ops = {
790 	.family =	PF_INET,
791 	.owner =	THIS_MODULE,
792 	.release =	inet_release,
793 	.bind =		inet_bind,
794 	.connect =	inet_stream_connect,
795 	.socketpair =	sock_no_socketpair,
796 	.accept =	inet_accept,
797 	.getname =	inet_getname,
798 	.poll =		tcp_poll,
799 	.ioctl =	inet_ioctl,
800 	.listen =	inet_listen,
801 	.shutdown =	inet_shutdown,
802 	.setsockopt =	sock_common_setsockopt,
803 	.getsockopt =	sock_common_getsockopt,
804 	.sendmsg =	inet_sendmsg,
805 	.recvmsg =	sock_common_recvmsg,
806 	.mmap =		sock_no_mmap,
807 	.sendpage =	tcp_sendpage
808 };
809 
810 struct proto_ops inet_dgram_ops = {
811 	.family =	PF_INET,
812 	.owner =	THIS_MODULE,
813 	.release =	inet_release,
814 	.bind =		inet_bind,
815 	.connect =	inet_dgram_connect,
816 	.socketpair =	sock_no_socketpair,
817 	.accept =	sock_no_accept,
818 	.getname =	inet_getname,
819 	.poll =		udp_poll,
820 	.ioctl =	inet_ioctl,
821 	.listen =	sock_no_listen,
822 	.shutdown =	inet_shutdown,
823 	.setsockopt =	sock_common_setsockopt,
824 	.getsockopt =	sock_common_getsockopt,
825 	.sendmsg =	inet_sendmsg,
826 	.recvmsg =	sock_common_recvmsg,
827 	.mmap =		sock_no_mmap,
828 	.sendpage =	inet_sendpage,
829 };
830 
831 /*
832  * For SOCK_RAW sockets; should be the same as inet_dgram_ops but without
833  * udp_poll
834  */
835 static struct proto_ops inet_sockraw_ops = {
836 	.family =	PF_INET,
837 	.owner =	THIS_MODULE,
838 	.release =	inet_release,
839 	.bind =		inet_bind,
840 	.connect =	inet_dgram_connect,
841 	.socketpair =	sock_no_socketpair,
842 	.accept =	sock_no_accept,
843 	.getname =	inet_getname,
844 	.poll =		datagram_poll,
845 	.ioctl =	inet_ioctl,
846 	.listen =	sock_no_listen,
847 	.shutdown =	inet_shutdown,
848 	.setsockopt =	sock_common_setsockopt,
849 	.getsockopt =	sock_common_getsockopt,
850 	.sendmsg =	inet_sendmsg,
851 	.recvmsg =	sock_common_recvmsg,
852 	.mmap =		sock_no_mmap,
853 	.sendpage =	inet_sendpage,
854 };
855 
856 static struct net_proto_family inet_family_ops = {
857 	.family = PF_INET,
858 	.create = inet_create,
859 	.owner	= THIS_MODULE,
860 };
861 
862 /* Upon startup we insert all the elements in inetsw_array[] into
863  * the linked list inetsw.
864  */
865 static struct inet_protosw inetsw_array[] =
866 {
867         {
868                 .type =       SOCK_STREAM,
869                 .protocol =   IPPROTO_TCP,
870                 .prot =       &tcp_prot,
871                 .ops =        &inet_stream_ops,
872                 .capability = -1,
873                 .no_check =   0,
874                 .flags =      INET_PROTOSW_PERMANENT,
875         },
876 
877         {
878                 .type =       SOCK_DGRAM,
879                 .protocol =   IPPROTO_UDP,
880                 .prot =       &udp_prot,
881                 .ops =        &inet_dgram_ops,
882                 .capability = -1,
883                 .no_check =   UDP_CSUM_DEFAULT,
884                 .flags =      INET_PROTOSW_PERMANENT,
885        },
886 
887 
888        {
889                .type =       SOCK_RAW,
890                .protocol =   IPPROTO_IP,	/* wild card */
891                .prot =       &raw_prot,
892                .ops =        &inet_sockraw_ops,
893                .capability = CAP_NET_RAW,
894                .no_check =   UDP_CSUM_DEFAULT,
895                .flags =      INET_PROTOSW_REUSE,
896        }
897 };
898 
899 #define INETSW_ARRAY_LEN (sizeof(inetsw_array) / sizeof(struct inet_protosw))
900 
901 void inet_register_protosw(struct inet_protosw *p)
902 {
903 	struct list_head *lh;
904 	struct inet_protosw *answer;
905 	int protocol = p->protocol;
906 	struct list_head *last_perm;
907 
908 	spin_lock_bh(&inetsw_lock);
909 
910 	if (p->type >= SOCK_MAX)
911 		goto out_illegal;
912 
913 	/* If we are trying to override a permanent protocol, bail. */
914 	answer = NULL;
915 	last_perm = &inetsw[p->type];
916 	list_for_each(lh, &inetsw[p->type]) {
917 		answer = list_entry(lh, struct inet_protosw, list);
918 
919 		/* Check only the non-wild match. */
920 		if (INET_PROTOSW_PERMANENT & answer->flags) {
921 			if (protocol == answer->protocol)
922 				break;
923 			last_perm = lh;
924 		}
925 
926 		answer = NULL;
927 	}
928 	if (answer)
929 		goto out_permanent;
930 
931 	/* Add the new entry after the last permanent entry if any, so that
932 	 * the new entry does not override a permanent entry when matched with
933 	 * a wild-card protocol. But it is allowed to override any existing
934 	 * non-permanent entry.  This means that when we remove this entry, the
935 	 * system automatically returns to the old behavior.
936 	 */
937 	list_add_rcu(&p->list, last_perm);
938 out:
939 	spin_unlock_bh(&inetsw_lock);
940 
941 	synchronize_net();
942 
943 	return;
944 
945 out_permanent:
946 	printk(KERN_ERR "Attempt to override permanent protocol %d.\n",
947 	       protocol);
948 	goto out;
949 
950 out_illegal:
951 	printk(KERN_ERR
952 	       "Ignoring attempt to register invalid socket type %d.\n",
953 	       p->type);
954 	goto out;
955 }
956 
957 void inet_unregister_protosw(struct inet_protosw *p)
958 {
959 	if (INET_PROTOSW_PERMANENT & p->flags) {
960 		printk(KERN_ERR
961 		       "Attempt to unregister permanent protocol %d.\n",
962 		       p->protocol);
963 	} else {
964 		spin_lock_bh(&inetsw_lock);
965 		list_del_rcu(&p->list);
966 		spin_unlock_bh(&inetsw_lock);
967 
968 		synchronize_net();
969 	}
970 }
971 
972 /*
973  *      Shall we try to damage output packets if routing dev changes?
974  */
975 
976 int sysctl_ip_dynaddr;
977 
978 static int inet_sk_reselect_saddr(struct sock *sk)
979 {
980 	struct inet_sock *inet = inet_sk(sk);
981 	int err;
982 	struct rtable *rt;
983 	__u32 old_saddr = inet->saddr;
984 	__u32 new_saddr;
985 	__u32 daddr = inet->daddr;
986 
987 	if (inet->opt && inet->opt->srr)
988 		daddr = inet->opt->faddr;
989 
990 	/* Query new route. */
991 	err = ip_route_connect(&rt, daddr, 0,
992 			       RT_CONN_FLAGS(sk),
993 			       sk->sk_bound_dev_if,
994 			       sk->sk_protocol,
995 			       inet->sport, inet->dport, sk);
996 	if (err)
997 		return err;
998 
999 	sk_setup_caps(sk, &rt->u.dst);
1000 
1001 	new_saddr = rt->rt_src;
1002 
1003 	if (new_saddr == old_saddr)
1004 		return 0;
1005 
1006 	if (sysctl_ip_dynaddr > 1) {
1007 		printk(KERN_INFO "%s(): shifting inet->"
1008 				 "saddr from %d.%d.%d.%d to %d.%d.%d.%d\n",
1009 		       __FUNCTION__,
1010 		       NIPQUAD(old_saddr),
1011 		       NIPQUAD(new_saddr));
1012 	}
1013 
1014 	inet->saddr = inet->rcv_saddr = new_saddr;
1015 
1016 	/*
1017 	 * XXX The only one ugly spot where we need to
1018 	 * XXX really change the sockets identity after
1019 	 * XXX it has entered the hashes. -DaveM
1020 	 *
1021 	 * Besides that, it does not check for connection
1022 	 * uniqueness. Wait for troubles.
1023 	 */
1024 	__sk_prot_rehash(sk);
1025 	return 0;
1026 }
1027 
1028 int inet_sk_rebuild_header(struct sock *sk)
1029 {
1030 	struct inet_sock *inet = inet_sk(sk);
1031 	struct rtable *rt = (struct rtable *)__sk_dst_check(sk, 0);
1032 	u32 daddr;
1033 	int err;
1034 
1035 	/* Route is OK, nothing to do. */
1036 	if (rt)
1037 		return 0;
1038 
1039 	/* Reroute. */
1040 	daddr = inet->daddr;
1041 	if (inet->opt && inet->opt->srr)
1042 		daddr = inet->opt->faddr;
1043 {
1044 	struct flowi fl = {
1045 		.oif = sk->sk_bound_dev_if,
1046 		.nl_u = {
1047 			.ip4_u = {
1048 				.daddr	= daddr,
1049 				.saddr	= inet->saddr,
1050 				.tos	= RT_CONN_FLAGS(sk),
1051 			},
1052 		},
1053 		.proto = sk->sk_protocol,
1054 		.uli_u = {
1055 			.ports = {
1056 				.sport = inet->sport,
1057 				.dport = inet->dport,
1058 			},
1059 		},
1060 	};
1061 
1062 	err = ip_route_output_flow(&rt, &fl, sk, 0);
1063 }
1064 	if (!err)
1065 		sk_setup_caps(sk, &rt->u.dst);
1066 	else {
1067 		/* Routing failed... */
1068 		sk->sk_route_caps = 0;
1069 		/*
1070 		 * Other protocols have to map its equivalent state to TCP_SYN_SENT.
1071 		 * DCCP maps its DCCP_REQUESTING state to TCP_SYN_SENT. -acme
1072 		 */
1073 		if (!sysctl_ip_dynaddr ||
1074 		    sk->sk_state != TCP_SYN_SENT ||
1075 		    (sk->sk_userlocks & SOCK_BINDADDR_LOCK) ||
1076 		    (err = inet_sk_reselect_saddr(sk)) != 0)
1077 			sk->sk_err_soft = -err;
1078 	}
1079 
1080 	return err;
1081 }
1082 
1083 EXPORT_SYMBOL(inet_sk_rebuild_header);
1084 
1085 #ifdef CONFIG_IP_MULTICAST
1086 static struct net_protocol igmp_protocol = {
1087 	.handler =	igmp_rcv,
1088 };
1089 #endif
1090 
1091 static struct net_protocol tcp_protocol = {
1092 	.handler =	tcp_v4_rcv,
1093 	.err_handler =	tcp_v4_err,
1094 	.no_policy =	1,
1095 };
1096 
1097 static struct net_protocol udp_protocol = {
1098 	.handler =	udp_rcv,
1099 	.err_handler =	udp_err,
1100 	.no_policy =	1,
1101 };
1102 
1103 static struct net_protocol icmp_protocol = {
1104 	.handler =	icmp_rcv,
1105 };
1106 
1107 static int __init init_ipv4_mibs(void)
1108 {
1109 	net_statistics[0] = alloc_percpu(struct linux_mib);
1110 	net_statistics[1] = alloc_percpu(struct linux_mib);
1111 	ip_statistics[0] = alloc_percpu(struct ipstats_mib);
1112 	ip_statistics[1] = alloc_percpu(struct ipstats_mib);
1113 	icmp_statistics[0] = alloc_percpu(struct icmp_mib);
1114 	icmp_statistics[1] = alloc_percpu(struct icmp_mib);
1115 	tcp_statistics[0] = alloc_percpu(struct tcp_mib);
1116 	tcp_statistics[1] = alloc_percpu(struct tcp_mib);
1117 	udp_statistics[0] = alloc_percpu(struct udp_mib);
1118 	udp_statistics[1] = alloc_percpu(struct udp_mib);
1119 	if (!
1120 	    (net_statistics[0] && net_statistics[1] && ip_statistics[0]
1121 	     && ip_statistics[1] && tcp_statistics[0] && tcp_statistics[1]
1122 	     && udp_statistics[0] && udp_statistics[1]))
1123 		return -ENOMEM;
1124 
1125 	(void) tcp_mib_init();
1126 
1127 	return 0;
1128 }
1129 
1130 static int ipv4_proc_init(void);
1131 
1132 /*
1133  *	IP protocol layer initialiser
1134  */
1135 
1136 static struct packet_type ip_packet_type = {
1137 	.type = __constant_htons(ETH_P_IP),
1138 	.func = ip_rcv,
1139 };
1140 
1141 static int __init inet_init(void)
1142 {
1143 	struct sk_buff *dummy_skb;
1144 	struct inet_protosw *q;
1145 	struct list_head *r;
1146 	int rc = -EINVAL;
1147 
1148 	if (sizeof(struct inet_skb_parm) > sizeof(dummy_skb->cb)) {
1149 		printk(KERN_CRIT "%s: panic\n", __FUNCTION__);
1150 		goto out;
1151 	}
1152 
1153 	rc = proto_register(&tcp_prot, 1);
1154 	if (rc)
1155 		goto out;
1156 
1157 	rc = proto_register(&udp_prot, 1);
1158 	if (rc)
1159 		goto out_unregister_tcp_proto;
1160 
1161 	rc = proto_register(&raw_prot, 1);
1162 	if (rc)
1163 		goto out_unregister_udp_proto;
1164 
1165 	/*
1166 	 *	Tell SOCKET that we are alive...
1167 	 */
1168 
1169   	(void)sock_register(&inet_family_ops);
1170 
1171 	/*
1172 	 *	Add all the base protocols.
1173 	 */
1174 
1175 	if (inet_add_protocol(&icmp_protocol, IPPROTO_ICMP) < 0)
1176 		printk(KERN_CRIT "inet_init: Cannot add ICMP protocol\n");
1177 	if (inet_add_protocol(&udp_protocol, IPPROTO_UDP) < 0)
1178 		printk(KERN_CRIT "inet_init: Cannot add UDP protocol\n");
1179 	if (inet_add_protocol(&tcp_protocol, IPPROTO_TCP) < 0)
1180 		printk(KERN_CRIT "inet_init: Cannot add TCP protocol\n");
1181 #ifdef CONFIG_IP_MULTICAST
1182 	if (inet_add_protocol(&igmp_protocol, IPPROTO_IGMP) < 0)
1183 		printk(KERN_CRIT "inet_init: Cannot add IGMP protocol\n");
1184 #endif
1185 
1186 	/* Register the socket-side information for inet_create. */
1187 	for (r = &inetsw[0]; r < &inetsw[SOCK_MAX]; ++r)
1188 		INIT_LIST_HEAD(r);
1189 
1190 	for (q = inetsw_array; q < &inetsw_array[INETSW_ARRAY_LEN]; ++q)
1191 		inet_register_protosw(q);
1192 
1193 	/*
1194 	 *	Set the ARP module up
1195 	 */
1196 
1197 	arp_init();
1198 
1199   	/*
1200   	 *	Set the IP module up
1201   	 */
1202 
1203 	ip_init();
1204 
1205 	tcp_v4_init(&inet_family_ops);
1206 
1207 	/* Setup TCP slab cache for open requests. */
1208 	tcp_init();
1209 
1210 
1211 	/*
1212 	 *	Set the ICMP layer up
1213 	 */
1214 
1215 	icmp_init(&inet_family_ops);
1216 
1217 	/*
1218 	 *	Initialise the multicast router
1219 	 */
1220 #if defined(CONFIG_IP_MROUTE)
1221 	ip_mr_init();
1222 #endif
1223 	/*
1224 	 *	Initialise per-cpu ipv4 mibs
1225 	 */
1226 
1227 	if(init_ipv4_mibs())
1228 		printk(KERN_CRIT "inet_init: Cannot init ipv4 mibs\n"); ;
1229 
1230 	ipv4_proc_init();
1231 
1232 	ipfrag_init();
1233 
1234 	dev_add_pack(&ip_packet_type);
1235 
1236 	rc = 0;
1237 out:
1238 	return rc;
1239 out_unregister_tcp_proto:
1240 	proto_unregister(&tcp_prot);
1241 out_unregister_udp_proto:
1242 	proto_unregister(&udp_prot);
1243 	goto out;
1244 }
1245 
1246 module_init(inet_init);
1247 
1248 /* ------------------------------------------------------------------------ */
1249 
1250 #ifdef CONFIG_PROC_FS
1251 static int __init ipv4_proc_init(void)
1252 {
1253 	int rc = 0;
1254 
1255 	if (raw_proc_init())
1256 		goto out_raw;
1257 	if (tcp4_proc_init())
1258 		goto out_tcp;
1259 	if (udp4_proc_init())
1260 		goto out_udp;
1261 	if (fib_proc_init())
1262 		goto out_fib;
1263 	if (ip_misc_proc_init())
1264 		goto out_misc;
1265 out:
1266 	return rc;
1267 out_misc:
1268 	fib_proc_exit();
1269 out_fib:
1270 	udp4_proc_exit();
1271 out_udp:
1272 	tcp4_proc_exit();
1273 out_tcp:
1274 	raw_proc_exit();
1275 out_raw:
1276 	rc = -ENOMEM;
1277 	goto out;
1278 }
1279 
1280 #else /* CONFIG_PROC_FS */
1281 static int __init ipv4_proc_init(void)
1282 {
1283 	return 0;
1284 }
1285 #endif /* CONFIG_PROC_FS */
1286 
1287 MODULE_ALIAS_NETPROTO(PF_INET);
1288 
1289 EXPORT_SYMBOL(inet_accept);
1290 EXPORT_SYMBOL(inet_bind);
1291 EXPORT_SYMBOL(inet_dgram_connect);
1292 EXPORT_SYMBOL(inet_dgram_ops);
1293 EXPORT_SYMBOL(inet_getname);
1294 EXPORT_SYMBOL(inet_ioctl);
1295 EXPORT_SYMBOL(inet_listen);
1296 EXPORT_SYMBOL(inet_register_protosw);
1297 EXPORT_SYMBOL(inet_release);
1298 EXPORT_SYMBOL(inet_sendmsg);
1299 EXPORT_SYMBOL(inet_shutdown);
1300 EXPORT_SYMBOL(inet_sock_destruct);
1301 EXPORT_SYMBOL(inet_stream_connect);
1302 EXPORT_SYMBOL(inet_stream_ops);
1303 EXPORT_SYMBOL(inet_unregister_protosw);
1304 EXPORT_SYMBOL(net_statistics);
1305 EXPORT_SYMBOL(sysctl_ip_nonlocal_bind);
1306