xref: /openbmc/linux/drivers/net/ppp/pppoe.c (revision 63dc02bd)
1 /** -*- linux-c -*- ***********************************************************
2  * Linux PPP over Ethernet (PPPoX/PPPoE) Sockets
3  *
4  * PPPoX --- Generic PPP encapsulation socket family
5  * PPPoE --- PPP over Ethernet (RFC 2516)
6  *
7  *
8  * Version:	0.7.0
9  *
10  * 070228 :	Fix to allow multiple sessions with same remote MAC and same
11  *		session id by including the local device ifindex in the
12  *		tuple identifying a session. This also ensures packets can't
13  *		be injected into a session from interfaces other than the one
14  *		specified by userspace. Florian Zumbiehl <florz@florz.de>
15  *		(Oh, BTW, this one is YYMMDD, in case you were wondering ...)
16  * 220102 :	Fix module use count on failure in pppoe_create, pppox_sk -acme
17  * 030700 :	Fixed connect logic to allow for disconnect.
18  * 270700 :	Fixed potential SMP problems; we must protect against
19  *		simultaneous invocation of ppp_input
20  *		and ppp_unregister_channel.
21  * 040800 :	Respect reference count mechanisms on net-devices.
22  * 200800 :	fix kfree(skb) in pppoe_rcv (acme)
23  *		Module reference count is decremented in the right spot now,
24  *		guards against sock_put not actually freeing the sk
25  *		in pppoe_release.
26  * 051000 :	Initialization cleanup.
27  * 111100 :	Fix recvmsg.
28  * 050101 :	Fix PADT procesing.
29  * 140501 :	Use pppoe_rcv_core to handle all backlog. (Alexey)
30  * 170701 :	Do not lock_sock with rwlock held. (DaveM)
31  *		Ignore discovery frames if user has socket
32  *		locked. (DaveM)
33  *		Ignore return value of dev_queue_xmit in __pppoe_xmit
34  *		or else we may kfree an SKB twice. (DaveM)
35  * 190701 :	When doing copies of skb's in __pppoe_xmit, always delete
36  *		the original skb that was passed in on success, never on
37  *		failure.  Delete the copy of the skb on failure to avoid
38  *		a memory leak.
39  * 081001 :	Misc. cleanup (licence string, non-blocking, prevent
40  *		reference of device on close).
41  * 121301 :	New ppp channels interface; cannot unregister a channel
42  *		from interrupts.  Thus, we mark the socket as a ZOMBIE
43  *		and do the unregistration later.
44  * 081002 :	seq_file support for proc stuff -acme
45  * 111602 :	Merge all 2.4 fixes into 2.5/2.6 tree.  Label 2.5/2.6
46  *		as version 0.7.  Spacing cleanup.
47  * Author:	Michal Ostrowski <mostrows@speakeasy.net>
48  * Contributors:
49  * 		Arnaldo Carvalho de Melo <acme@conectiva.com.br>
50  *		David S. Miller (davem@redhat.com)
51  *
52  * License:
53  *		This program is free software; you can redistribute it and/or
54  *		modify it under the terms of the GNU General Public License
55  *		as published by the Free Software Foundation; either version
56  *		2 of the License, or (at your option) any later version.
57  *
58  */
59 
60 #include <linux/string.h>
61 #include <linux/module.h>
62 #include <linux/kernel.h>
63 #include <linux/slab.h>
64 #include <linux/errno.h>
65 #include <linux/netdevice.h>
66 #include <linux/net.h>
67 #include <linux/inetdevice.h>
68 #include <linux/etherdevice.h>
69 #include <linux/skbuff.h>
70 #include <linux/init.h>
71 #include <linux/if_ether.h>
72 #include <linux/if_pppox.h>
73 #include <linux/ppp_channel.h>
74 #include <linux/ppp_defs.h>
75 #include <linux/ppp-ioctl.h>
76 #include <linux/notifier.h>
77 #include <linux/file.h>
78 #include <linux/proc_fs.h>
79 #include <linux/seq_file.h>
80 
81 #include <linux/nsproxy.h>
82 #include <net/net_namespace.h>
83 #include <net/netns/generic.h>
84 #include <net/sock.h>
85 
86 #include <asm/uaccess.h>
87 
88 #define PPPOE_HASH_BITS 4
89 #define PPPOE_HASH_SIZE (1 << PPPOE_HASH_BITS)
90 #define PPPOE_HASH_MASK	(PPPOE_HASH_SIZE - 1)
91 
92 static int __pppoe_xmit(struct sock *sk, struct sk_buff *skb);
93 
94 static const struct proto_ops pppoe_ops;
95 static const struct ppp_channel_ops pppoe_chan_ops;
96 
97 /* per-net private data for this module */
98 static int pppoe_net_id __read_mostly;
99 struct pppoe_net {
100 	/*
101 	 * we could use _single_ hash table for all
102 	 * nets by injecting net id into the hash but
103 	 * it would increase hash chains and add
104 	 * a few additional math comparations messy
105 	 * as well, moreover in case of SMP less locking
106 	 * controversy here
107 	 */
108 	struct pppox_sock *hash_table[PPPOE_HASH_SIZE];
109 	rwlock_t hash_lock;
110 };
111 
112 /*
113  * PPPoE could be in the following stages:
114  * 1) Discovery stage (to obtain remote MAC and Session ID)
115  * 2) Session stage (MAC and SID are known)
116  *
117  * Ethernet frames have a special tag for this but
118  * we use simpler approach based on session id
119  */
120 static inline bool stage_session(__be16 sid)
121 {
122 	return sid != 0;
123 }
124 
125 static inline struct pppoe_net *pppoe_pernet(struct net *net)
126 {
127 	BUG_ON(!net);
128 
129 	return net_generic(net, pppoe_net_id);
130 }
131 
132 static inline int cmp_2_addr(struct pppoe_addr *a, struct pppoe_addr *b)
133 {
134 	return a->sid == b->sid && !memcmp(a->remote, b->remote, ETH_ALEN);
135 }
136 
137 static inline int cmp_addr(struct pppoe_addr *a, __be16 sid, char *addr)
138 {
139 	return a->sid == sid && !memcmp(a->remote, addr, ETH_ALEN);
140 }
141 
142 #if 8 % PPPOE_HASH_BITS
143 #error 8 must be a multiple of PPPOE_HASH_BITS
144 #endif
145 
146 static int hash_item(__be16 sid, unsigned char *addr)
147 {
148 	unsigned char hash = 0;
149 	unsigned int i;
150 
151 	for (i = 0; i < ETH_ALEN; i++)
152 		hash ^= addr[i];
153 	for (i = 0; i < sizeof(sid_t) * 8; i += 8)
154 		hash ^= (__force __u32)sid >> i;
155 	for (i = 8; (i >>= 1) >= PPPOE_HASH_BITS;)
156 		hash ^= hash >> i;
157 
158 	return hash & PPPOE_HASH_MASK;
159 }
160 
161 /**********************************************************************
162  *
163  *  Set/get/delete/rehash items  (internal versions)
164  *
165  **********************************************************************/
166 static struct pppox_sock *__get_item(struct pppoe_net *pn, __be16 sid,
167 				unsigned char *addr, int ifindex)
168 {
169 	int hash = hash_item(sid, addr);
170 	struct pppox_sock *ret;
171 
172 	ret = pn->hash_table[hash];
173 	while (ret) {
174 		if (cmp_addr(&ret->pppoe_pa, sid, addr) &&
175 		    ret->pppoe_ifindex == ifindex)
176 			return ret;
177 
178 		ret = ret->next;
179 	}
180 
181 	return NULL;
182 }
183 
184 static int __set_item(struct pppoe_net *pn, struct pppox_sock *po)
185 {
186 	int hash = hash_item(po->pppoe_pa.sid, po->pppoe_pa.remote);
187 	struct pppox_sock *ret;
188 
189 	ret = pn->hash_table[hash];
190 	while (ret) {
191 		if (cmp_2_addr(&ret->pppoe_pa, &po->pppoe_pa) &&
192 		    ret->pppoe_ifindex == po->pppoe_ifindex)
193 			return -EALREADY;
194 
195 		ret = ret->next;
196 	}
197 
198 	po->next = pn->hash_table[hash];
199 	pn->hash_table[hash] = po;
200 
201 	return 0;
202 }
203 
204 static struct pppox_sock *__delete_item(struct pppoe_net *pn, __be16 sid,
205 					char *addr, int ifindex)
206 {
207 	int hash = hash_item(sid, addr);
208 	struct pppox_sock *ret, **src;
209 
210 	ret = pn->hash_table[hash];
211 	src = &pn->hash_table[hash];
212 
213 	while (ret) {
214 		if (cmp_addr(&ret->pppoe_pa, sid, addr) &&
215 		    ret->pppoe_ifindex == ifindex) {
216 			*src = ret->next;
217 			break;
218 		}
219 
220 		src = &ret->next;
221 		ret = ret->next;
222 	}
223 
224 	return ret;
225 }
226 
227 /**********************************************************************
228  *
229  *  Set/get/delete/rehash items
230  *
231  **********************************************************************/
232 static inline struct pppox_sock *get_item(struct pppoe_net *pn, __be16 sid,
233 					unsigned char *addr, int ifindex)
234 {
235 	struct pppox_sock *po;
236 
237 	read_lock_bh(&pn->hash_lock);
238 	po = __get_item(pn, sid, addr, ifindex);
239 	if (po)
240 		sock_hold(sk_pppox(po));
241 	read_unlock_bh(&pn->hash_lock);
242 
243 	return po;
244 }
245 
246 static inline struct pppox_sock *get_item_by_addr(struct net *net,
247 						struct sockaddr_pppox *sp)
248 {
249 	struct net_device *dev;
250 	struct pppoe_net *pn;
251 	struct pppox_sock *pppox_sock = NULL;
252 
253 	int ifindex;
254 
255 	rcu_read_lock();
256 	dev = dev_get_by_name_rcu(net, sp->sa_addr.pppoe.dev);
257 	if (dev) {
258 		ifindex = dev->ifindex;
259 		pn = pppoe_pernet(net);
260 		pppox_sock = get_item(pn, sp->sa_addr.pppoe.sid,
261 				sp->sa_addr.pppoe.remote, ifindex);
262 	}
263 	rcu_read_unlock();
264 	return pppox_sock;
265 }
266 
267 static inline struct pppox_sock *delete_item(struct pppoe_net *pn, __be16 sid,
268 					char *addr, int ifindex)
269 {
270 	struct pppox_sock *ret;
271 
272 	write_lock_bh(&pn->hash_lock);
273 	ret = __delete_item(pn, sid, addr, ifindex);
274 	write_unlock_bh(&pn->hash_lock);
275 
276 	return ret;
277 }
278 
279 /***************************************************************************
280  *
281  *  Handler for device events.
282  *  Certain device events require that sockets be unconnected.
283  *
284  **************************************************************************/
285 
286 static void pppoe_flush_dev(struct net_device *dev)
287 {
288 	struct pppoe_net *pn;
289 	int i;
290 
291 	pn = pppoe_pernet(dev_net(dev));
292 	write_lock_bh(&pn->hash_lock);
293 	for (i = 0; i < PPPOE_HASH_SIZE; i++) {
294 		struct pppox_sock *po = pn->hash_table[i];
295 		struct sock *sk;
296 
297 		while (po) {
298 			while (po && po->pppoe_dev != dev) {
299 				po = po->next;
300 			}
301 
302 			if (!po)
303 				break;
304 
305 			sk = sk_pppox(po);
306 
307 			/* We always grab the socket lock, followed by the
308 			 * hash_lock, in that order.  Since we should hold the
309 			 * sock lock while doing any unbinding, we need to
310 			 * release the lock we're holding.  Hold a reference to
311 			 * the sock so it doesn't disappear as we're jumping
312 			 * between locks.
313 			 */
314 
315 			sock_hold(sk);
316 			write_unlock_bh(&pn->hash_lock);
317 			lock_sock(sk);
318 
319 			if (po->pppoe_dev == dev &&
320 			    sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND | PPPOX_ZOMBIE)) {
321 				pppox_unbind_sock(sk);
322 				sk->sk_state = PPPOX_ZOMBIE;
323 				sk->sk_state_change(sk);
324 				po->pppoe_dev = NULL;
325 				dev_put(dev);
326 			}
327 
328 			release_sock(sk);
329 			sock_put(sk);
330 
331 			/* Restart the process from the start of the current
332 			 * hash chain. We dropped locks so the world may have
333 			 * change from underneath us.
334 			 */
335 
336 			BUG_ON(pppoe_pernet(dev_net(dev)) == NULL);
337 			write_lock_bh(&pn->hash_lock);
338 			po = pn->hash_table[i];
339 		}
340 	}
341 	write_unlock_bh(&pn->hash_lock);
342 }
343 
344 static int pppoe_device_event(struct notifier_block *this,
345 			      unsigned long event, void *ptr)
346 {
347 	struct net_device *dev = (struct net_device *)ptr;
348 
349 	/* Only look at sockets that are using this specific device. */
350 	switch (event) {
351 	case NETDEV_CHANGEADDR:
352 	case NETDEV_CHANGEMTU:
353 		/* A change in mtu or address is a bad thing, requiring
354 		 * LCP re-negotiation.
355 		 */
356 
357 	case NETDEV_GOING_DOWN:
358 	case NETDEV_DOWN:
359 		/* Find every socket on this device and kill it. */
360 		pppoe_flush_dev(dev);
361 		break;
362 
363 	default:
364 		break;
365 	}
366 
367 	return NOTIFY_DONE;
368 }
369 
370 static struct notifier_block pppoe_notifier = {
371 	.notifier_call = pppoe_device_event,
372 };
373 
374 /************************************************************************
375  *
376  * Do the real work of receiving a PPPoE Session frame.
377  *
378  ***********************************************************************/
379 static int pppoe_rcv_core(struct sock *sk, struct sk_buff *skb)
380 {
381 	struct pppox_sock *po = pppox_sk(sk);
382 	struct pppox_sock *relay_po;
383 
384 	/* Backlog receive. Semantics of backlog rcv preclude any code from
385 	 * executing in lock_sock()/release_sock() bounds; meaning sk->sk_state
386 	 * can't change.
387 	 */
388 
389 	if (sk->sk_state & PPPOX_BOUND) {
390 		ppp_input(&po->chan, skb);
391 	} else if (sk->sk_state & PPPOX_RELAY) {
392 		relay_po = get_item_by_addr(sock_net(sk),
393 					    &po->pppoe_relay);
394 		if (relay_po == NULL)
395 			goto abort_kfree;
396 
397 		if ((sk_pppox(relay_po)->sk_state & PPPOX_CONNECTED) == 0)
398 			goto abort_put;
399 
400 		if (!__pppoe_xmit(sk_pppox(relay_po), skb))
401 			goto abort_put;
402 	} else {
403 		if (sock_queue_rcv_skb(sk, skb))
404 			goto abort_kfree;
405 	}
406 
407 	return NET_RX_SUCCESS;
408 
409 abort_put:
410 	sock_put(sk_pppox(relay_po));
411 
412 abort_kfree:
413 	kfree_skb(skb);
414 	return NET_RX_DROP;
415 }
416 
417 /************************************************************************
418  *
419  * Receive wrapper called in BH context.
420  *
421  ***********************************************************************/
422 static int pppoe_rcv(struct sk_buff *skb, struct net_device *dev,
423 		     struct packet_type *pt, struct net_device *orig_dev)
424 {
425 	struct pppoe_hdr *ph;
426 	struct pppox_sock *po;
427 	struct pppoe_net *pn;
428 	int len;
429 
430 	skb = skb_share_check(skb, GFP_ATOMIC);
431 	if (!skb)
432 		goto out;
433 
434 	if (!pskb_may_pull(skb, sizeof(struct pppoe_hdr)))
435 		goto drop;
436 
437 	ph = pppoe_hdr(skb);
438 	len = ntohs(ph->length);
439 
440 	skb_pull_rcsum(skb, sizeof(*ph));
441 	if (skb->len < len)
442 		goto drop;
443 
444 	if (pskb_trim_rcsum(skb, len))
445 		goto drop;
446 
447 	pn = pppoe_pernet(dev_net(dev));
448 
449 	/* Note that get_item does a sock_hold(), so sk_pppox(po)
450 	 * is known to be safe.
451 	 */
452 	po = get_item(pn, ph->sid, eth_hdr(skb)->h_source, dev->ifindex);
453 	if (!po)
454 		goto drop;
455 
456 	return sk_receive_skb(sk_pppox(po), skb, 0);
457 
458 drop:
459 	kfree_skb(skb);
460 out:
461 	return NET_RX_DROP;
462 }
463 
464 /************************************************************************
465  *
466  * Receive a PPPoE Discovery frame.
467  * This is solely for detection of PADT frames
468  *
469  ***********************************************************************/
470 static int pppoe_disc_rcv(struct sk_buff *skb, struct net_device *dev,
471 			  struct packet_type *pt, struct net_device *orig_dev)
472 
473 {
474 	struct pppoe_hdr *ph;
475 	struct pppox_sock *po;
476 	struct pppoe_net *pn;
477 
478 	skb = skb_share_check(skb, GFP_ATOMIC);
479 	if (!skb)
480 		goto out;
481 
482 	if (!pskb_may_pull(skb, sizeof(struct pppoe_hdr)))
483 		goto abort;
484 
485 	ph = pppoe_hdr(skb);
486 	if (ph->code != PADT_CODE)
487 		goto abort;
488 
489 	pn = pppoe_pernet(dev_net(dev));
490 	po = get_item(pn, ph->sid, eth_hdr(skb)->h_source, dev->ifindex);
491 	if (po) {
492 		struct sock *sk = sk_pppox(po);
493 
494 		bh_lock_sock(sk);
495 
496 		/* If the user has locked the socket, just ignore
497 		 * the packet.  With the way two rcv protocols hook into
498 		 * one socket family type, we cannot (easily) distinguish
499 		 * what kind of SKB it is during backlog rcv.
500 		 */
501 		if (sock_owned_by_user(sk) == 0) {
502 			/* We're no longer connect at the PPPOE layer,
503 			 * and must wait for ppp channel to disconnect us.
504 			 */
505 			sk->sk_state = PPPOX_ZOMBIE;
506 		}
507 
508 		bh_unlock_sock(sk);
509 		sock_put(sk);
510 	}
511 
512 abort:
513 	kfree_skb(skb);
514 out:
515 	return NET_RX_SUCCESS; /* Lies... :-) */
516 }
517 
518 static struct packet_type pppoes_ptype __read_mostly = {
519 	.type	= cpu_to_be16(ETH_P_PPP_SES),
520 	.func	= pppoe_rcv,
521 };
522 
523 static struct packet_type pppoed_ptype __read_mostly = {
524 	.type	= cpu_to_be16(ETH_P_PPP_DISC),
525 	.func	= pppoe_disc_rcv,
526 };
527 
528 static struct proto pppoe_sk_proto __read_mostly = {
529 	.name	  = "PPPOE",
530 	.owner	  = THIS_MODULE,
531 	.obj_size = sizeof(struct pppox_sock),
532 };
533 
534 /***********************************************************************
535  *
536  * Initialize a new struct sock.
537  *
538  **********************************************************************/
539 static int pppoe_create(struct net *net, struct socket *sock)
540 {
541 	struct sock *sk;
542 
543 	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pppoe_sk_proto);
544 	if (!sk)
545 		return -ENOMEM;
546 
547 	sock_init_data(sock, sk);
548 
549 	sock->state	= SS_UNCONNECTED;
550 	sock->ops	= &pppoe_ops;
551 
552 	sk->sk_backlog_rcv	= pppoe_rcv_core;
553 	sk->sk_state		= PPPOX_NONE;
554 	sk->sk_type		= SOCK_STREAM;
555 	sk->sk_family		= PF_PPPOX;
556 	sk->sk_protocol		= PX_PROTO_OE;
557 
558 	return 0;
559 }
560 
561 static int pppoe_release(struct socket *sock)
562 {
563 	struct sock *sk = sock->sk;
564 	struct pppox_sock *po;
565 	struct pppoe_net *pn;
566 	struct net *net = NULL;
567 
568 	if (!sk)
569 		return 0;
570 
571 	lock_sock(sk);
572 	if (sock_flag(sk, SOCK_DEAD)) {
573 		release_sock(sk);
574 		return -EBADF;
575 	}
576 
577 	po = pppox_sk(sk);
578 
579 	if (sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND)) {
580 		dev_put(po->pppoe_dev);
581 		po->pppoe_dev = NULL;
582 	}
583 
584 	pppox_unbind_sock(sk);
585 
586 	/* Signal the death of the socket. */
587 	sk->sk_state = PPPOX_DEAD;
588 
589 	net = sock_net(sk);
590 	pn = pppoe_pernet(net);
591 
592 	/*
593 	 * protect "po" from concurrent updates
594 	 * on pppoe_flush_dev
595 	 */
596 	delete_item(pn, po->pppoe_pa.sid, po->pppoe_pa.remote,
597 		    po->pppoe_ifindex);
598 
599 	sock_orphan(sk);
600 	sock->sk = NULL;
601 
602 	skb_queue_purge(&sk->sk_receive_queue);
603 	release_sock(sk);
604 	sock_put(sk);
605 
606 	return 0;
607 }
608 
609 static int pppoe_connect(struct socket *sock, struct sockaddr *uservaddr,
610 		  int sockaddr_len, int flags)
611 {
612 	struct sock *sk = sock->sk;
613 	struct sockaddr_pppox *sp = (struct sockaddr_pppox *)uservaddr;
614 	struct pppox_sock *po = pppox_sk(sk);
615 	struct net_device *dev = NULL;
616 	struct pppoe_net *pn;
617 	struct net *net = NULL;
618 	int error;
619 
620 	lock_sock(sk);
621 
622 	error = -EINVAL;
623 	if (sp->sa_protocol != PX_PROTO_OE)
624 		goto end;
625 
626 	/* Check for already bound sockets */
627 	error = -EBUSY;
628 	if ((sk->sk_state & PPPOX_CONNECTED) &&
629 	     stage_session(sp->sa_addr.pppoe.sid))
630 		goto end;
631 
632 	/* Check for already disconnected sockets, on attempts to disconnect */
633 	error = -EALREADY;
634 	if ((sk->sk_state & PPPOX_DEAD) &&
635 	     !stage_session(sp->sa_addr.pppoe.sid))
636 		goto end;
637 
638 	error = 0;
639 
640 	/* Delete the old binding */
641 	if (stage_session(po->pppoe_pa.sid)) {
642 		pppox_unbind_sock(sk);
643 		pn = pppoe_pernet(sock_net(sk));
644 		delete_item(pn, po->pppoe_pa.sid,
645 			    po->pppoe_pa.remote, po->pppoe_ifindex);
646 		if (po->pppoe_dev) {
647 			dev_put(po->pppoe_dev);
648 			po->pppoe_dev = NULL;
649 		}
650 
651 		memset(sk_pppox(po) + 1, 0,
652 		       sizeof(struct pppox_sock) - sizeof(struct sock));
653 		sk->sk_state = PPPOX_NONE;
654 	}
655 
656 	/* Re-bind in session stage only */
657 	if (stage_session(sp->sa_addr.pppoe.sid)) {
658 		error = -ENODEV;
659 		net = sock_net(sk);
660 		dev = dev_get_by_name(net, sp->sa_addr.pppoe.dev);
661 		if (!dev)
662 			goto err_put;
663 
664 		po->pppoe_dev = dev;
665 		po->pppoe_ifindex = dev->ifindex;
666 		pn = pppoe_pernet(net);
667 		if (!(dev->flags & IFF_UP)) {
668 			goto err_put;
669 		}
670 
671 		memcpy(&po->pppoe_pa,
672 		       &sp->sa_addr.pppoe,
673 		       sizeof(struct pppoe_addr));
674 
675 		write_lock_bh(&pn->hash_lock);
676 		error = __set_item(pn, po);
677 		write_unlock_bh(&pn->hash_lock);
678 		if (error < 0)
679 			goto err_put;
680 
681 		po->chan.hdrlen = (sizeof(struct pppoe_hdr) +
682 				   dev->hard_header_len);
683 
684 		po->chan.mtu = dev->mtu - sizeof(struct pppoe_hdr);
685 		po->chan.private = sk;
686 		po->chan.ops = &pppoe_chan_ops;
687 
688 		error = ppp_register_net_channel(dev_net(dev), &po->chan);
689 		if (error) {
690 			delete_item(pn, po->pppoe_pa.sid,
691 				    po->pppoe_pa.remote, po->pppoe_ifindex);
692 			goto err_put;
693 		}
694 
695 		sk->sk_state = PPPOX_CONNECTED;
696 	}
697 
698 	po->num = sp->sa_addr.pppoe.sid;
699 
700 end:
701 	release_sock(sk);
702 	return error;
703 err_put:
704 	if (po->pppoe_dev) {
705 		dev_put(po->pppoe_dev);
706 		po->pppoe_dev = NULL;
707 	}
708 	goto end;
709 }
710 
711 static int pppoe_getname(struct socket *sock, struct sockaddr *uaddr,
712 		  int *usockaddr_len, int peer)
713 {
714 	int len = sizeof(struct sockaddr_pppox);
715 	struct sockaddr_pppox sp;
716 
717 	sp.sa_family	= AF_PPPOX;
718 	sp.sa_protocol	= PX_PROTO_OE;
719 	memcpy(&sp.sa_addr.pppoe, &pppox_sk(sock->sk)->pppoe_pa,
720 	       sizeof(struct pppoe_addr));
721 
722 	memcpy(uaddr, &sp, len);
723 
724 	*usockaddr_len = len;
725 
726 	return 0;
727 }
728 
729 static int pppoe_ioctl(struct socket *sock, unsigned int cmd,
730 		unsigned long arg)
731 {
732 	struct sock *sk = sock->sk;
733 	struct pppox_sock *po = pppox_sk(sk);
734 	int val;
735 	int err;
736 
737 	switch (cmd) {
738 	case PPPIOCGMRU:
739 		err = -ENXIO;
740 		if (!(sk->sk_state & PPPOX_CONNECTED))
741 			break;
742 
743 		err = -EFAULT;
744 		if (put_user(po->pppoe_dev->mtu -
745 			     sizeof(struct pppoe_hdr) -
746 			     PPP_HDRLEN,
747 			     (int __user *)arg))
748 			break;
749 		err = 0;
750 		break;
751 
752 	case PPPIOCSMRU:
753 		err = -ENXIO;
754 		if (!(sk->sk_state & PPPOX_CONNECTED))
755 			break;
756 
757 		err = -EFAULT;
758 		if (get_user(val, (int __user *)arg))
759 			break;
760 
761 		if (val < (po->pppoe_dev->mtu
762 			   - sizeof(struct pppoe_hdr)
763 			   - PPP_HDRLEN))
764 			err = 0;
765 		else
766 			err = -EINVAL;
767 		break;
768 
769 	case PPPIOCSFLAGS:
770 		err = -EFAULT;
771 		if (get_user(val, (int __user *)arg))
772 			break;
773 		err = 0;
774 		break;
775 
776 	case PPPOEIOCSFWD:
777 	{
778 		struct pppox_sock *relay_po;
779 
780 		err = -EBUSY;
781 		if (sk->sk_state & (PPPOX_BOUND | PPPOX_ZOMBIE | PPPOX_DEAD))
782 			break;
783 
784 		err = -ENOTCONN;
785 		if (!(sk->sk_state & PPPOX_CONNECTED))
786 			break;
787 
788 		/* PPPoE address from the user specifies an outbound
789 		   PPPoE address which frames are forwarded to */
790 		err = -EFAULT;
791 		if (copy_from_user(&po->pppoe_relay,
792 				   (void __user *)arg,
793 				   sizeof(struct sockaddr_pppox)))
794 			break;
795 
796 		err = -EINVAL;
797 		if (po->pppoe_relay.sa_family != AF_PPPOX ||
798 		    po->pppoe_relay.sa_protocol != PX_PROTO_OE)
799 			break;
800 
801 		/* Check that the socket referenced by the address
802 		   actually exists. */
803 		relay_po = get_item_by_addr(sock_net(sk), &po->pppoe_relay);
804 		if (!relay_po)
805 			break;
806 
807 		sock_put(sk_pppox(relay_po));
808 		sk->sk_state |= PPPOX_RELAY;
809 		err = 0;
810 		break;
811 	}
812 
813 	case PPPOEIOCDFWD:
814 		err = -EALREADY;
815 		if (!(sk->sk_state & PPPOX_RELAY))
816 			break;
817 
818 		sk->sk_state &= ~PPPOX_RELAY;
819 		err = 0;
820 		break;
821 
822 	default:
823 		err = -ENOTTY;
824 	}
825 
826 	return err;
827 }
828 
829 static int pppoe_sendmsg(struct kiocb *iocb, struct socket *sock,
830 		  struct msghdr *m, size_t total_len)
831 {
832 	struct sk_buff *skb;
833 	struct sock *sk = sock->sk;
834 	struct pppox_sock *po = pppox_sk(sk);
835 	int error;
836 	struct pppoe_hdr hdr;
837 	struct pppoe_hdr *ph;
838 	struct net_device *dev;
839 	char *start;
840 
841 	lock_sock(sk);
842 	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED)) {
843 		error = -ENOTCONN;
844 		goto end;
845 	}
846 
847 	hdr.ver = 1;
848 	hdr.type = 1;
849 	hdr.code = 0;
850 	hdr.sid = po->num;
851 
852 	dev = po->pppoe_dev;
853 
854 	error = -EMSGSIZE;
855 	if (total_len > (dev->mtu + dev->hard_header_len))
856 		goto end;
857 
858 
859 	skb = sock_wmalloc(sk, total_len + dev->hard_header_len + 32,
860 			   0, GFP_KERNEL);
861 	if (!skb) {
862 		error = -ENOMEM;
863 		goto end;
864 	}
865 
866 	/* Reserve space for headers. */
867 	skb_reserve(skb, dev->hard_header_len);
868 	skb_reset_network_header(skb);
869 
870 	skb->dev = dev;
871 
872 	skb->priority = sk->sk_priority;
873 	skb->protocol = cpu_to_be16(ETH_P_PPP_SES);
874 
875 	ph = (struct pppoe_hdr *)skb_put(skb, total_len + sizeof(struct pppoe_hdr));
876 	start = (char *)&ph->tag[0];
877 
878 	error = memcpy_fromiovec(start, m->msg_iov, total_len);
879 	if (error < 0) {
880 		kfree_skb(skb);
881 		goto end;
882 	}
883 
884 	error = total_len;
885 	dev_hard_header(skb, dev, ETH_P_PPP_SES,
886 			po->pppoe_pa.remote, NULL, total_len);
887 
888 	memcpy(ph, &hdr, sizeof(struct pppoe_hdr));
889 
890 	ph->length = htons(total_len);
891 
892 	dev_queue_xmit(skb);
893 
894 end:
895 	release_sock(sk);
896 	return error;
897 }
898 
899 /************************************************************************
900  *
901  * xmit function for internal use.
902  *
903  ***********************************************************************/
904 static int __pppoe_xmit(struct sock *sk, struct sk_buff *skb)
905 {
906 	struct pppox_sock *po = pppox_sk(sk);
907 	struct net_device *dev = po->pppoe_dev;
908 	struct pppoe_hdr *ph;
909 	int data_len = skb->len;
910 
911 	/* The higher-level PPP code (ppp_unregister_channel()) ensures the PPP
912 	 * xmit operations conclude prior to an unregistration call.  Thus
913 	 * sk->sk_state cannot change, so we don't need to do lock_sock().
914 	 * But, we also can't do a lock_sock since that introduces a potential
915 	 * deadlock as we'd reverse the lock ordering used when calling
916 	 * ppp_unregister_channel().
917 	 */
918 
919 	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
920 		goto abort;
921 
922 	if (!dev)
923 		goto abort;
924 
925 	/* Copy the data if there is no space for the header or if it's
926 	 * read-only.
927 	 */
928 	if (skb_cow_head(skb, sizeof(*ph) + dev->hard_header_len))
929 		goto abort;
930 
931 	__skb_push(skb, sizeof(*ph));
932 	skb_reset_network_header(skb);
933 
934 	ph = pppoe_hdr(skb);
935 	ph->ver	= 1;
936 	ph->type = 1;
937 	ph->code = 0;
938 	ph->sid	= po->num;
939 	ph->length = htons(data_len);
940 
941 	skb->protocol = cpu_to_be16(ETH_P_PPP_SES);
942 	skb->dev = dev;
943 
944 	dev_hard_header(skb, dev, ETH_P_PPP_SES,
945 			po->pppoe_pa.remote, NULL, data_len);
946 
947 	dev_queue_xmit(skb);
948 	return 1;
949 
950 abort:
951 	kfree_skb(skb);
952 	return 1;
953 }
954 
955 /************************************************************************
956  *
957  * xmit function called by generic PPP driver
958  * sends PPP frame over PPPoE socket
959  *
960  ***********************************************************************/
961 static int pppoe_xmit(struct ppp_channel *chan, struct sk_buff *skb)
962 {
963 	struct sock *sk = (struct sock *)chan->private;
964 	return __pppoe_xmit(sk, skb);
965 }
966 
967 static const struct ppp_channel_ops pppoe_chan_ops = {
968 	.start_xmit = pppoe_xmit,
969 };
970 
971 static int pppoe_recvmsg(struct kiocb *iocb, struct socket *sock,
972 		  struct msghdr *m, size_t total_len, int flags)
973 {
974 	struct sock *sk = sock->sk;
975 	struct sk_buff *skb;
976 	int error = 0;
977 
978 	if (sk->sk_state & PPPOX_BOUND) {
979 		error = -EIO;
980 		goto end;
981 	}
982 
983 	skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT,
984 				flags & MSG_DONTWAIT, &error);
985 	if (error < 0)
986 		goto end;
987 
988 	m->msg_namelen = 0;
989 
990 	if (skb) {
991 		total_len = min_t(size_t, total_len, skb->len);
992 		error = skb_copy_datagram_iovec(skb, 0, m->msg_iov, total_len);
993 		if (error == 0)
994 			error = total_len;
995 	}
996 
997 	kfree_skb(skb);
998 end:
999 	return error;
1000 }
1001 
1002 #ifdef CONFIG_PROC_FS
1003 static int pppoe_seq_show(struct seq_file *seq, void *v)
1004 {
1005 	struct pppox_sock *po;
1006 	char *dev_name;
1007 
1008 	if (v == SEQ_START_TOKEN) {
1009 		seq_puts(seq, "Id       Address              Device\n");
1010 		goto out;
1011 	}
1012 
1013 	po = v;
1014 	dev_name = po->pppoe_pa.dev;
1015 
1016 	seq_printf(seq, "%08X %pM %8s\n",
1017 		po->pppoe_pa.sid, po->pppoe_pa.remote, dev_name);
1018 out:
1019 	return 0;
1020 }
1021 
1022 static inline struct pppox_sock *pppoe_get_idx(struct pppoe_net *pn, loff_t pos)
1023 {
1024 	struct pppox_sock *po;
1025 	int i;
1026 
1027 	for (i = 0; i < PPPOE_HASH_SIZE; i++) {
1028 		po = pn->hash_table[i];
1029 		while (po) {
1030 			if (!pos--)
1031 				goto out;
1032 			po = po->next;
1033 		}
1034 	}
1035 
1036 out:
1037 	return po;
1038 }
1039 
1040 static void *pppoe_seq_start(struct seq_file *seq, loff_t *pos)
1041 	__acquires(pn->hash_lock)
1042 {
1043 	struct pppoe_net *pn = pppoe_pernet(seq_file_net(seq));
1044 	loff_t l = *pos;
1045 
1046 	read_lock_bh(&pn->hash_lock);
1047 	return l ? pppoe_get_idx(pn, --l) : SEQ_START_TOKEN;
1048 }
1049 
1050 static void *pppoe_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1051 {
1052 	struct pppoe_net *pn = pppoe_pernet(seq_file_net(seq));
1053 	struct pppox_sock *po;
1054 
1055 	++*pos;
1056 	if (v == SEQ_START_TOKEN) {
1057 		po = pppoe_get_idx(pn, 0);
1058 		goto out;
1059 	}
1060 	po = v;
1061 	if (po->next)
1062 		po = po->next;
1063 	else {
1064 		int hash = hash_item(po->pppoe_pa.sid, po->pppoe_pa.remote);
1065 
1066 		po = NULL;
1067 		while (++hash < PPPOE_HASH_SIZE) {
1068 			po = pn->hash_table[hash];
1069 			if (po)
1070 				break;
1071 		}
1072 	}
1073 
1074 out:
1075 	return po;
1076 }
1077 
1078 static void pppoe_seq_stop(struct seq_file *seq, void *v)
1079 	__releases(pn->hash_lock)
1080 {
1081 	struct pppoe_net *pn = pppoe_pernet(seq_file_net(seq));
1082 	read_unlock_bh(&pn->hash_lock);
1083 }
1084 
1085 static const struct seq_operations pppoe_seq_ops = {
1086 	.start		= pppoe_seq_start,
1087 	.next		= pppoe_seq_next,
1088 	.stop		= pppoe_seq_stop,
1089 	.show		= pppoe_seq_show,
1090 };
1091 
1092 static int pppoe_seq_open(struct inode *inode, struct file *file)
1093 {
1094 	return seq_open_net(inode, file, &pppoe_seq_ops,
1095 			sizeof(struct seq_net_private));
1096 }
1097 
1098 static const struct file_operations pppoe_seq_fops = {
1099 	.owner		= THIS_MODULE,
1100 	.open		= pppoe_seq_open,
1101 	.read		= seq_read,
1102 	.llseek		= seq_lseek,
1103 	.release	= seq_release_net,
1104 };
1105 
1106 #endif /* CONFIG_PROC_FS */
1107 
1108 static const struct proto_ops pppoe_ops = {
1109 	.family		= AF_PPPOX,
1110 	.owner		= THIS_MODULE,
1111 	.release	= pppoe_release,
1112 	.bind		= sock_no_bind,
1113 	.connect	= pppoe_connect,
1114 	.socketpair	= sock_no_socketpair,
1115 	.accept		= sock_no_accept,
1116 	.getname	= pppoe_getname,
1117 	.poll		= datagram_poll,
1118 	.listen		= sock_no_listen,
1119 	.shutdown	= sock_no_shutdown,
1120 	.setsockopt	= sock_no_setsockopt,
1121 	.getsockopt	= sock_no_getsockopt,
1122 	.sendmsg	= pppoe_sendmsg,
1123 	.recvmsg	= pppoe_recvmsg,
1124 	.mmap		= sock_no_mmap,
1125 	.ioctl		= pppox_ioctl,
1126 };
1127 
1128 static const struct pppox_proto pppoe_proto = {
1129 	.create	= pppoe_create,
1130 	.ioctl	= pppoe_ioctl,
1131 	.owner	= THIS_MODULE,
1132 };
1133 
1134 static __net_init int pppoe_init_net(struct net *net)
1135 {
1136 	struct pppoe_net *pn = pppoe_pernet(net);
1137 	struct proc_dir_entry *pde;
1138 
1139 	rwlock_init(&pn->hash_lock);
1140 
1141 	pde = proc_net_fops_create(net, "pppoe", S_IRUGO, &pppoe_seq_fops);
1142 #ifdef CONFIG_PROC_FS
1143 	if (!pde)
1144 		return -ENOMEM;
1145 #endif
1146 
1147 	return 0;
1148 }
1149 
1150 static __net_exit void pppoe_exit_net(struct net *net)
1151 {
1152 	proc_net_remove(net, "pppoe");
1153 }
1154 
1155 static struct pernet_operations pppoe_net_ops = {
1156 	.init = pppoe_init_net,
1157 	.exit = pppoe_exit_net,
1158 	.id   = &pppoe_net_id,
1159 	.size = sizeof(struct pppoe_net),
1160 };
1161 
1162 static int __init pppoe_init(void)
1163 {
1164 	int err;
1165 
1166 	err = register_pernet_device(&pppoe_net_ops);
1167 	if (err)
1168 		goto out;
1169 
1170 	err = proto_register(&pppoe_sk_proto, 0);
1171 	if (err)
1172 		goto out_unregister_net_ops;
1173 
1174 	err = register_pppox_proto(PX_PROTO_OE, &pppoe_proto);
1175 	if (err)
1176 		goto out_unregister_pppoe_proto;
1177 
1178 	dev_add_pack(&pppoes_ptype);
1179 	dev_add_pack(&pppoed_ptype);
1180 	register_netdevice_notifier(&pppoe_notifier);
1181 
1182 	return 0;
1183 
1184 out_unregister_pppoe_proto:
1185 	proto_unregister(&pppoe_sk_proto);
1186 out_unregister_net_ops:
1187 	unregister_pernet_device(&pppoe_net_ops);
1188 out:
1189 	return err;
1190 }
1191 
1192 static void __exit pppoe_exit(void)
1193 {
1194 	unregister_netdevice_notifier(&pppoe_notifier);
1195 	dev_remove_pack(&pppoed_ptype);
1196 	dev_remove_pack(&pppoes_ptype);
1197 	unregister_pppox_proto(PX_PROTO_OE);
1198 	proto_unregister(&pppoe_sk_proto);
1199 	unregister_pernet_device(&pppoe_net_ops);
1200 }
1201 
1202 module_init(pppoe_init);
1203 module_exit(pppoe_exit);
1204 
1205 MODULE_AUTHOR("Michal Ostrowski <mostrows@speakeasy.net>");
1206 MODULE_DESCRIPTION("PPP over Ethernet driver");
1207 MODULE_LICENSE("GPL");
1208 MODULE_ALIAS_NETPROTO(PF_PPPOX);
1209