xref: /openbmc/linux/drivers/net/ppp/ppp_generic.c (revision 6774def6)
1 /*
2  * Generic PPP layer for Linux.
3  *
4  * Copyright 1999-2002 Paul Mackerras.
5  *
6  *  This program is free software; you can redistribute it and/or
7  *  modify it under the terms of the GNU General Public License
8  *  as published by the Free Software Foundation; either version
9  *  2 of the License, or (at your option) any later version.
10  *
11  * The generic PPP layer handles the PPP network interfaces, the
12  * /dev/ppp device, packet and VJ compression, and multilink.
13  * It talks to PPP `channels' via the interface defined in
14  * include/linux/ppp_channel.h.  Channels provide the basic means for
15  * sending and receiving PPP frames on some kind of communications
16  * channel.
17  *
18  * Part of the code in this driver was inspired by the old async-only
19  * PPP driver, written by Michael Callahan and Al Longyear, and
20  * subsequently hacked by Paul Mackerras.
21  *
22  * ==FILEVERSION 20041108==
23  */
24 
25 #include <linux/module.h>
26 #include <linux/kernel.h>
27 #include <linux/kmod.h>
28 #include <linux/init.h>
29 #include <linux/list.h>
30 #include <linux/idr.h>
31 #include <linux/netdevice.h>
32 #include <linux/poll.h>
33 #include <linux/ppp_defs.h>
34 #include <linux/filter.h>
35 #include <linux/ppp-ioctl.h>
36 #include <linux/ppp_channel.h>
37 #include <linux/ppp-comp.h>
38 #include <linux/skbuff.h>
39 #include <linux/rtnetlink.h>
40 #include <linux/if_arp.h>
41 #include <linux/ip.h>
42 #include <linux/tcp.h>
43 #include <linux/spinlock.h>
44 #include <linux/rwsem.h>
45 #include <linux/stddef.h>
46 #include <linux/device.h>
47 #include <linux/mutex.h>
48 #include <linux/slab.h>
49 #include <asm/unaligned.h>
50 #include <net/slhc_vj.h>
51 #include <linux/atomic.h>
52 
53 #include <linux/nsproxy.h>
54 #include <net/net_namespace.h>
55 #include <net/netns/generic.h>
56 
57 #define PPP_VERSION	"2.4.2"
58 
59 /*
60  * Network protocols we support.
61  */
62 #define NP_IP	0		/* Internet Protocol V4 */
63 #define NP_IPV6	1		/* Internet Protocol V6 */
64 #define NP_IPX	2		/* IPX protocol */
65 #define NP_AT	3		/* Appletalk protocol */
66 #define NP_MPLS_UC 4		/* MPLS unicast */
67 #define NP_MPLS_MC 5		/* MPLS multicast */
68 #define NUM_NP	6		/* Number of NPs. */
69 
70 #define MPHDRLEN	6	/* multilink protocol header length */
71 #define MPHDRLEN_SSN	4	/* ditto with short sequence numbers */
72 
73 /*
74  * An instance of /dev/ppp can be associated with either a ppp
75  * interface unit or a ppp channel.  In both cases, file->private_data
76  * points to one of these.
77  */
78 struct ppp_file {
79 	enum {
80 		INTERFACE=1, CHANNEL
81 	}		kind;
82 	struct sk_buff_head xq;		/* pppd transmit queue */
83 	struct sk_buff_head rq;		/* receive queue for pppd */
84 	wait_queue_head_t rwait;	/* for poll on reading /dev/ppp */
85 	atomic_t	refcnt;		/* # refs (incl /dev/ppp attached) */
86 	int		hdrlen;		/* space to leave for headers */
87 	int		index;		/* interface unit / channel number */
88 	int		dead;		/* unit/channel has been shut down */
89 };
90 
91 #define PF_TO_X(pf, X)		container_of(pf, X, file)
92 
93 #define PF_TO_PPP(pf)		PF_TO_X(pf, struct ppp)
94 #define PF_TO_CHANNEL(pf)	PF_TO_X(pf, struct channel)
95 
96 /*
97  * Data structure to hold primary network stats for which
98  * we want to use 64 bit storage.  Other network stats
99  * are stored in dev->stats of the ppp strucute.
100  */
101 struct ppp_link_stats {
102 	u64 rx_packets;
103 	u64 tx_packets;
104 	u64 rx_bytes;
105 	u64 tx_bytes;
106 };
107 
108 /*
109  * Data structure describing one ppp unit.
110  * A ppp unit corresponds to a ppp network interface device
111  * and represents a multilink bundle.
112  * It can have 0 or more ppp channels connected to it.
113  */
114 struct ppp {
115 	struct ppp_file	file;		/* stuff for read/write/poll 0 */
116 	struct file	*owner;		/* file that owns this unit 48 */
117 	struct list_head channels;	/* list of attached channels 4c */
118 	int		n_channels;	/* how many channels are attached 54 */
119 	spinlock_t	rlock;		/* lock for receive side 58 */
120 	spinlock_t	wlock;		/* lock for transmit side 5c */
121 	int		mru;		/* max receive unit 60 */
122 	unsigned int	flags;		/* control bits 64 */
123 	unsigned int	xstate;		/* transmit state bits 68 */
124 	unsigned int	rstate;		/* receive state bits 6c */
125 	int		debug;		/* debug flags 70 */
126 	struct slcompress *vj;		/* state for VJ header compression */
127 	enum NPmode	npmode[NUM_NP];	/* what to do with each net proto 78 */
128 	struct sk_buff	*xmit_pending;	/* a packet ready to go out 88 */
129 	struct compressor *xcomp;	/* transmit packet compressor 8c */
130 	void		*xc_state;	/* its internal state 90 */
131 	struct compressor *rcomp;	/* receive decompressor 94 */
132 	void		*rc_state;	/* its internal state 98 */
133 	unsigned long	last_xmit;	/* jiffies when last pkt sent 9c */
134 	unsigned long	last_recv;	/* jiffies when last pkt rcvd a0 */
135 	struct net_device *dev;		/* network interface device a4 */
136 	int		closing;	/* is device closing down? a8 */
137 #ifdef CONFIG_PPP_MULTILINK
138 	int		nxchan;		/* next channel to send something on */
139 	u32		nxseq;		/* next sequence number to send */
140 	int		mrru;		/* MP: max reconst. receive unit */
141 	u32		nextseq;	/* MP: seq no of next packet */
142 	u32		minseq;		/* MP: min of most recent seqnos */
143 	struct sk_buff_head mrq;	/* MP: receive reconstruction queue */
144 #endif /* CONFIG_PPP_MULTILINK */
145 #ifdef CONFIG_PPP_FILTER
146 	struct bpf_prog *pass_filter;	/* filter for packets to pass */
147 	struct bpf_prog *active_filter; /* filter for pkts to reset idle */
148 #endif /* CONFIG_PPP_FILTER */
149 	struct net	*ppp_net;	/* the net we belong to */
150 	struct ppp_link_stats stats64;	/* 64 bit network stats */
151 };
152 
153 /*
154  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
155  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
156  * SC_MUST_COMP
157  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
158  * Bits in xstate: SC_COMP_RUN
159  */
160 #define SC_FLAG_BITS	(SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
161 			 |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
162 			 |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
163 
164 /*
165  * Private data structure for each channel.
166  * This includes the data structure used for multilink.
167  */
168 struct channel {
169 	struct ppp_file	file;		/* stuff for read/write/poll */
170 	struct list_head list;		/* link in all/new_channels list */
171 	struct ppp_channel *chan;	/* public channel data structure */
172 	struct rw_semaphore chan_sem;	/* protects `chan' during chan ioctl */
173 	spinlock_t	downl;		/* protects `chan', file.xq dequeue */
174 	struct ppp	*ppp;		/* ppp unit we're connected to */
175 	struct net	*chan_net;	/* the net channel belongs to */
176 	struct list_head clist;		/* link in list of channels per unit */
177 	rwlock_t	upl;		/* protects `ppp' */
178 #ifdef CONFIG_PPP_MULTILINK
179 	u8		avail;		/* flag used in multilink stuff */
180 	u8		had_frag;	/* >= 1 fragments have been sent */
181 	u32		lastseq;	/* MP: last sequence # received */
182 	int		speed;		/* speed of the corresponding ppp channel*/
183 #endif /* CONFIG_PPP_MULTILINK */
184 };
185 
186 /*
187  * SMP locking issues:
188  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
189  * list and the ppp.n_channels field, you need to take both locks
190  * before you modify them.
191  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
192  * channel.downl.
193  */
194 
195 static DEFINE_MUTEX(ppp_mutex);
196 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
197 static atomic_t channel_count = ATOMIC_INIT(0);
198 
199 /* per-net private data for this module */
200 static int ppp_net_id __read_mostly;
201 struct ppp_net {
202 	/* units to ppp mapping */
203 	struct idr units_idr;
204 
205 	/*
206 	 * all_ppp_mutex protects the units_idr mapping.
207 	 * It also ensures that finding a ppp unit in the units_idr
208 	 * map and updating its file.refcnt field is atomic.
209 	 */
210 	struct mutex all_ppp_mutex;
211 
212 	/* channels */
213 	struct list_head all_channels;
214 	struct list_head new_channels;
215 	int last_channel_index;
216 
217 	/*
218 	 * all_channels_lock protects all_channels and
219 	 * last_channel_index, and the atomicity of find
220 	 * a channel and updating its file.refcnt field.
221 	 */
222 	spinlock_t all_channels_lock;
223 };
224 
225 /* Get the PPP protocol number from a skb */
226 #define PPP_PROTO(skb)	get_unaligned_be16((skb)->data)
227 
228 /* We limit the length of ppp->file.rq to this (arbitrary) value */
229 #define PPP_MAX_RQLEN	32
230 
231 /*
232  * Maximum number of multilink fragments queued up.
233  * This has to be large enough to cope with the maximum latency of
234  * the slowest channel relative to the others.  Strictly it should
235  * depend on the number of channels and their characteristics.
236  */
237 #define PPP_MP_MAX_QLEN	128
238 
239 /* Multilink header bits. */
240 #define B	0x80		/* this fragment begins a packet */
241 #define E	0x40		/* this fragment ends a packet */
242 
243 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
244 #define seq_before(a, b)	((s32)((a) - (b)) < 0)
245 #define seq_after(a, b)		((s32)((a) - (b)) > 0)
246 
247 /* Prototypes. */
248 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
249 			struct file *file, unsigned int cmd, unsigned long arg);
250 static void ppp_xmit_process(struct ppp *ppp);
251 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
252 static void ppp_push(struct ppp *ppp);
253 static void ppp_channel_push(struct channel *pch);
254 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
255 			      struct channel *pch);
256 static void ppp_receive_error(struct ppp *ppp);
257 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
258 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
259 					    struct sk_buff *skb);
260 #ifdef CONFIG_PPP_MULTILINK
261 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
262 				struct channel *pch);
263 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
264 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
265 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
266 #endif /* CONFIG_PPP_MULTILINK */
267 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
268 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
269 static void ppp_ccp_closed(struct ppp *ppp);
270 static struct compressor *find_compressor(int type);
271 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
272 static struct ppp *ppp_create_interface(struct net *net, int unit, int *retp);
273 static void init_ppp_file(struct ppp_file *pf, int kind);
274 static void ppp_shutdown_interface(struct ppp *ppp);
275 static void ppp_destroy_interface(struct ppp *ppp);
276 static struct ppp *ppp_find_unit(struct ppp_net *pn, int unit);
277 static struct channel *ppp_find_channel(struct ppp_net *pn, int unit);
278 static int ppp_connect_channel(struct channel *pch, int unit);
279 static int ppp_disconnect_channel(struct channel *pch);
280 static void ppp_destroy_channel(struct channel *pch);
281 static int unit_get(struct idr *p, void *ptr);
282 static int unit_set(struct idr *p, void *ptr, int n);
283 static void unit_put(struct idr *p, int n);
284 static void *unit_find(struct idr *p, int n);
285 
286 static struct class *ppp_class;
287 
288 /* per net-namespace data */
289 static inline struct ppp_net *ppp_pernet(struct net *net)
290 {
291 	BUG_ON(!net);
292 
293 	return net_generic(net, ppp_net_id);
294 }
295 
296 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
297 static inline int proto_to_npindex(int proto)
298 {
299 	switch (proto) {
300 	case PPP_IP:
301 		return NP_IP;
302 	case PPP_IPV6:
303 		return NP_IPV6;
304 	case PPP_IPX:
305 		return NP_IPX;
306 	case PPP_AT:
307 		return NP_AT;
308 	case PPP_MPLS_UC:
309 		return NP_MPLS_UC;
310 	case PPP_MPLS_MC:
311 		return NP_MPLS_MC;
312 	}
313 	return -EINVAL;
314 }
315 
316 /* Translates an NP index into a PPP protocol number */
317 static const int npindex_to_proto[NUM_NP] = {
318 	PPP_IP,
319 	PPP_IPV6,
320 	PPP_IPX,
321 	PPP_AT,
322 	PPP_MPLS_UC,
323 	PPP_MPLS_MC,
324 };
325 
326 /* Translates an ethertype into an NP index */
327 static inline int ethertype_to_npindex(int ethertype)
328 {
329 	switch (ethertype) {
330 	case ETH_P_IP:
331 		return NP_IP;
332 	case ETH_P_IPV6:
333 		return NP_IPV6;
334 	case ETH_P_IPX:
335 		return NP_IPX;
336 	case ETH_P_PPPTALK:
337 	case ETH_P_ATALK:
338 		return NP_AT;
339 	case ETH_P_MPLS_UC:
340 		return NP_MPLS_UC;
341 	case ETH_P_MPLS_MC:
342 		return NP_MPLS_MC;
343 	}
344 	return -1;
345 }
346 
347 /* Translates an NP index into an ethertype */
348 static const int npindex_to_ethertype[NUM_NP] = {
349 	ETH_P_IP,
350 	ETH_P_IPV6,
351 	ETH_P_IPX,
352 	ETH_P_PPPTALK,
353 	ETH_P_MPLS_UC,
354 	ETH_P_MPLS_MC,
355 };
356 
357 /*
358  * Locking shorthand.
359  */
360 #define ppp_xmit_lock(ppp)	spin_lock_bh(&(ppp)->wlock)
361 #define ppp_xmit_unlock(ppp)	spin_unlock_bh(&(ppp)->wlock)
362 #define ppp_recv_lock(ppp)	spin_lock_bh(&(ppp)->rlock)
363 #define ppp_recv_unlock(ppp)	spin_unlock_bh(&(ppp)->rlock)
364 #define ppp_lock(ppp)		do { ppp_xmit_lock(ppp); \
365 				     ppp_recv_lock(ppp); } while (0)
366 #define ppp_unlock(ppp)		do { ppp_recv_unlock(ppp); \
367 				     ppp_xmit_unlock(ppp); } while (0)
368 
369 /*
370  * /dev/ppp device routines.
371  * The /dev/ppp device is used by pppd to control the ppp unit.
372  * It supports the read, write, ioctl and poll functions.
373  * Open instances of /dev/ppp can be in one of three states:
374  * unattached, attached to a ppp unit, or attached to a ppp channel.
375  */
376 static int ppp_open(struct inode *inode, struct file *file)
377 {
378 	/*
379 	 * This could (should?) be enforced by the permissions on /dev/ppp.
380 	 */
381 	if (!capable(CAP_NET_ADMIN))
382 		return -EPERM;
383 	return 0;
384 }
385 
386 static int ppp_release(struct inode *unused, struct file *file)
387 {
388 	struct ppp_file *pf = file->private_data;
389 	struct ppp *ppp;
390 
391 	if (pf) {
392 		file->private_data = NULL;
393 		if (pf->kind == INTERFACE) {
394 			ppp = PF_TO_PPP(pf);
395 			if (file == ppp->owner)
396 				ppp_shutdown_interface(ppp);
397 		}
398 		if (atomic_dec_and_test(&pf->refcnt)) {
399 			switch (pf->kind) {
400 			case INTERFACE:
401 				ppp_destroy_interface(PF_TO_PPP(pf));
402 				break;
403 			case CHANNEL:
404 				ppp_destroy_channel(PF_TO_CHANNEL(pf));
405 				break;
406 			}
407 		}
408 	}
409 	return 0;
410 }
411 
412 static ssize_t ppp_read(struct file *file, char __user *buf,
413 			size_t count, loff_t *ppos)
414 {
415 	struct ppp_file *pf = file->private_data;
416 	DECLARE_WAITQUEUE(wait, current);
417 	ssize_t ret;
418 	struct sk_buff *skb = NULL;
419 	struct iovec iov;
420 
421 	ret = count;
422 
423 	if (!pf)
424 		return -ENXIO;
425 	add_wait_queue(&pf->rwait, &wait);
426 	for (;;) {
427 		set_current_state(TASK_INTERRUPTIBLE);
428 		skb = skb_dequeue(&pf->rq);
429 		if (skb)
430 			break;
431 		ret = 0;
432 		if (pf->dead)
433 			break;
434 		if (pf->kind == INTERFACE) {
435 			/*
436 			 * Return 0 (EOF) on an interface that has no
437 			 * channels connected, unless it is looping
438 			 * network traffic (demand mode).
439 			 */
440 			struct ppp *ppp = PF_TO_PPP(pf);
441 			if (ppp->n_channels == 0 &&
442 			    (ppp->flags & SC_LOOP_TRAFFIC) == 0)
443 				break;
444 		}
445 		ret = -EAGAIN;
446 		if (file->f_flags & O_NONBLOCK)
447 			break;
448 		ret = -ERESTARTSYS;
449 		if (signal_pending(current))
450 			break;
451 		schedule();
452 	}
453 	set_current_state(TASK_RUNNING);
454 	remove_wait_queue(&pf->rwait, &wait);
455 
456 	if (!skb)
457 		goto out;
458 
459 	ret = -EOVERFLOW;
460 	if (skb->len > count)
461 		goto outf;
462 	ret = -EFAULT;
463 	iov.iov_base = buf;
464 	iov.iov_len = count;
465 	if (skb_copy_datagram_iovec(skb, 0, &iov, skb->len))
466 		goto outf;
467 	ret = skb->len;
468 
469  outf:
470 	kfree_skb(skb);
471  out:
472 	return ret;
473 }
474 
475 static ssize_t ppp_write(struct file *file, const char __user *buf,
476 			 size_t count, loff_t *ppos)
477 {
478 	struct ppp_file *pf = file->private_data;
479 	struct sk_buff *skb;
480 	ssize_t ret;
481 
482 	if (!pf)
483 		return -ENXIO;
484 	ret = -ENOMEM;
485 	skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
486 	if (!skb)
487 		goto out;
488 	skb_reserve(skb, pf->hdrlen);
489 	ret = -EFAULT;
490 	if (copy_from_user(skb_put(skb, count), buf, count)) {
491 		kfree_skb(skb);
492 		goto out;
493 	}
494 
495 	skb_queue_tail(&pf->xq, skb);
496 
497 	switch (pf->kind) {
498 	case INTERFACE:
499 		ppp_xmit_process(PF_TO_PPP(pf));
500 		break;
501 	case CHANNEL:
502 		ppp_channel_push(PF_TO_CHANNEL(pf));
503 		break;
504 	}
505 
506 	ret = count;
507 
508  out:
509 	return ret;
510 }
511 
512 /* No kernel lock - fine */
513 static unsigned int ppp_poll(struct file *file, poll_table *wait)
514 {
515 	struct ppp_file *pf = file->private_data;
516 	unsigned int mask;
517 
518 	if (!pf)
519 		return 0;
520 	poll_wait(file, &pf->rwait, wait);
521 	mask = POLLOUT | POLLWRNORM;
522 	if (skb_peek(&pf->rq))
523 		mask |= POLLIN | POLLRDNORM;
524 	if (pf->dead)
525 		mask |= POLLHUP;
526 	else if (pf->kind == INTERFACE) {
527 		/* see comment in ppp_read */
528 		struct ppp *ppp = PF_TO_PPP(pf);
529 		if (ppp->n_channels == 0 &&
530 		    (ppp->flags & SC_LOOP_TRAFFIC) == 0)
531 			mask |= POLLIN | POLLRDNORM;
532 	}
533 
534 	return mask;
535 }
536 
537 #ifdef CONFIG_PPP_FILTER
538 static int get_filter(void __user *arg, struct sock_filter **p)
539 {
540 	struct sock_fprog uprog;
541 	struct sock_filter *code = NULL;
542 	int len;
543 
544 	if (copy_from_user(&uprog, arg, sizeof(uprog)))
545 		return -EFAULT;
546 
547 	if (!uprog.len) {
548 		*p = NULL;
549 		return 0;
550 	}
551 
552 	len = uprog.len * sizeof(struct sock_filter);
553 	code = memdup_user(uprog.filter, len);
554 	if (IS_ERR(code))
555 		return PTR_ERR(code);
556 
557 	*p = code;
558 	return uprog.len;
559 }
560 #endif /* CONFIG_PPP_FILTER */
561 
562 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
563 {
564 	struct ppp_file *pf = file->private_data;
565 	struct ppp *ppp;
566 	int err = -EFAULT, val, val2, i;
567 	struct ppp_idle idle;
568 	struct npioctl npi;
569 	int unit, cflags;
570 	struct slcompress *vj;
571 	void __user *argp = (void __user *)arg;
572 	int __user *p = argp;
573 
574 	if (!pf)
575 		return ppp_unattached_ioctl(current->nsproxy->net_ns,
576 					pf, file, cmd, arg);
577 
578 	if (cmd == PPPIOCDETACH) {
579 		/*
580 		 * We have to be careful here... if the file descriptor
581 		 * has been dup'd, we could have another process in the
582 		 * middle of a poll using the same file *, so we had
583 		 * better not free the interface data structures -
584 		 * instead we fail the ioctl.  Even in this case, we
585 		 * shut down the interface if we are the owner of it.
586 		 * Actually, we should get rid of PPPIOCDETACH, userland
587 		 * (i.e. pppd) could achieve the same effect by closing
588 		 * this fd and reopening /dev/ppp.
589 		 */
590 		err = -EINVAL;
591 		mutex_lock(&ppp_mutex);
592 		if (pf->kind == INTERFACE) {
593 			ppp = PF_TO_PPP(pf);
594 			if (file == ppp->owner)
595 				ppp_shutdown_interface(ppp);
596 		}
597 		if (atomic_long_read(&file->f_count) < 2) {
598 			ppp_release(NULL, file);
599 			err = 0;
600 		} else
601 			pr_warn("PPPIOCDETACH file->f_count=%ld\n",
602 				atomic_long_read(&file->f_count));
603 		mutex_unlock(&ppp_mutex);
604 		return err;
605 	}
606 
607 	if (pf->kind == CHANNEL) {
608 		struct channel *pch;
609 		struct ppp_channel *chan;
610 
611 		mutex_lock(&ppp_mutex);
612 		pch = PF_TO_CHANNEL(pf);
613 
614 		switch (cmd) {
615 		case PPPIOCCONNECT:
616 			if (get_user(unit, p))
617 				break;
618 			err = ppp_connect_channel(pch, unit);
619 			break;
620 
621 		case PPPIOCDISCONN:
622 			err = ppp_disconnect_channel(pch);
623 			break;
624 
625 		default:
626 			down_read(&pch->chan_sem);
627 			chan = pch->chan;
628 			err = -ENOTTY;
629 			if (chan && chan->ops->ioctl)
630 				err = chan->ops->ioctl(chan, cmd, arg);
631 			up_read(&pch->chan_sem);
632 		}
633 		mutex_unlock(&ppp_mutex);
634 		return err;
635 	}
636 
637 	if (pf->kind != INTERFACE) {
638 		/* can't happen */
639 		pr_err("PPP: not interface or channel??\n");
640 		return -EINVAL;
641 	}
642 
643 	mutex_lock(&ppp_mutex);
644 	ppp = PF_TO_PPP(pf);
645 	switch (cmd) {
646 	case PPPIOCSMRU:
647 		if (get_user(val, p))
648 			break;
649 		ppp->mru = val;
650 		err = 0;
651 		break;
652 
653 	case PPPIOCSFLAGS:
654 		if (get_user(val, p))
655 			break;
656 		ppp_lock(ppp);
657 		cflags = ppp->flags & ~val;
658 #ifdef CONFIG_PPP_MULTILINK
659 		if (!(ppp->flags & SC_MULTILINK) && (val & SC_MULTILINK))
660 			ppp->nextseq = 0;
661 #endif
662 		ppp->flags = val & SC_FLAG_BITS;
663 		ppp_unlock(ppp);
664 		if (cflags & SC_CCP_OPEN)
665 			ppp_ccp_closed(ppp);
666 		err = 0;
667 		break;
668 
669 	case PPPIOCGFLAGS:
670 		val = ppp->flags | ppp->xstate | ppp->rstate;
671 		if (put_user(val, p))
672 			break;
673 		err = 0;
674 		break;
675 
676 	case PPPIOCSCOMPRESS:
677 		err = ppp_set_compress(ppp, arg);
678 		break;
679 
680 	case PPPIOCGUNIT:
681 		if (put_user(ppp->file.index, p))
682 			break;
683 		err = 0;
684 		break;
685 
686 	case PPPIOCSDEBUG:
687 		if (get_user(val, p))
688 			break;
689 		ppp->debug = val;
690 		err = 0;
691 		break;
692 
693 	case PPPIOCGDEBUG:
694 		if (put_user(ppp->debug, p))
695 			break;
696 		err = 0;
697 		break;
698 
699 	case PPPIOCGIDLE:
700 		idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
701 		idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
702 		if (copy_to_user(argp, &idle, sizeof(idle)))
703 			break;
704 		err = 0;
705 		break;
706 
707 	case PPPIOCSMAXCID:
708 		if (get_user(val, p))
709 			break;
710 		val2 = 15;
711 		if ((val >> 16) != 0) {
712 			val2 = val >> 16;
713 			val &= 0xffff;
714 		}
715 		vj = slhc_init(val2+1, val+1);
716 		if (!vj) {
717 			netdev_err(ppp->dev,
718 				   "PPP: no memory (VJ compressor)\n");
719 			err = -ENOMEM;
720 			break;
721 		}
722 		ppp_lock(ppp);
723 		if (ppp->vj)
724 			slhc_free(ppp->vj);
725 		ppp->vj = vj;
726 		ppp_unlock(ppp);
727 		err = 0;
728 		break;
729 
730 	case PPPIOCGNPMODE:
731 	case PPPIOCSNPMODE:
732 		if (copy_from_user(&npi, argp, sizeof(npi)))
733 			break;
734 		err = proto_to_npindex(npi.protocol);
735 		if (err < 0)
736 			break;
737 		i = err;
738 		if (cmd == PPPIOCGNPMODE) {
739 			err = -EFAULT;
740 			npi.mode = ppp->npmode[i];
741 			if (copy_to_user(argp, &npi, sizeof(npi)))
742 				break;
743 		} else {
744 			ppp->npmode[i] = npi.mode;
745 			/* we may be able to transmit more packets now (??) */
746 			netif_wake_queue(ppp->dev);
747 		}
748 		err = 0;
749 		break;
750 
751 #ifdef CONFIG_PPP_FILTER
752 	case PPPIOCSPASS:
753 	{
754 		struct sock_filter *code;
755 
756 		err = get_filter(argp, &code);
757 		if (err >= 0) {
758 			struct bpf_prog *pass_filter = NULL;
759 			struct sock_fprog_kern fprog = {
760 				.len = err,
761 				.filter = code,
762 			};
763 
764 			err = 0;
765 			if (fprog.filter)
766 				err = bpf_prog_create(&pass_filter, &fprog);
767 			if (!err) {
768 				ppp_lock(ppp);
769 				if (ppp->pass_filter)
770 					bpf_prog_destroy(ppp->pass_filter);
771 				ppp->pass_filter = pass_filter;
772 				ppp_unlock(ppp);
773 			}
774 			kfree(code);
775 		}
776 		break;
777 	}
778 	case PPPIOCSACTIVE:
779 	{
780 		struct sock_filter *code;
781 
782 		err = get_filter(argp, &code);
783 		if (err >= 0) {
784 			struct bpf_prog *active_filter = NULL;
785 			struct sock_fprog_kern fprog = {
786 				.len = err,
787 				.filter = code,
788 			};
789 
790 			err = 0;
791 			if (fprog.filter)
792 				err = bpf_prog_create(&active_filter, &fprog);
793 			if (!err) {
794 				ppp_lock(ppp);
795 				if (ppp->active_filter)
796 					bpf_prog_destroy(ppp->active_filter);
797 				ppp->active_filter = active_filter;
798 				ppp_unlock(ppp);
799 			}
800 			kfree(code);
801 		}
802 		break;
803 	}
804 #endif /* CONFIG_PPP_FILTER */
805 
806 #ifdef CONFIG_PPP_MULTILINK
807 	case PPPIOCSMRRU:
808 		if (get_user(val, p))
809 			break;
810 		ppp_recv_lock(ppp);
811 		ppp->mrru = val;
812 		ppp_recv_unlock(ppp);
813 		err = 0;
814 		break;
815 #endif /* CONFIG_PPP_MULTILINK */
816 
817 	default:
818 		err = -ENOTTY;
819 	}
820 	mutex_unlock(&ppp_mutex);
821 	return err;
822 }
823 
824 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
825 			struct file *file, unsigned int cmd, unsigned long arg)
826 {
827 	int unit, err = -EFAULT;
828 	struct ppp *ppp;
829 	struct channel *chan;
830 	struct ppp_net *pn;
831 	int __user *p = (int __user *)arg;
832 
833 	mutex_lock(&ppp_mutex);
834 	switch (cmd) {
835 	case PPPIOCNEWUNIT:
836 		/* Create a new ppp unit */
837 		if (get_user(unit, p))
838 			break;
839 		ppp = ppp_create_interface(net, unit, &err);
840 		if (!ppp)
841 			break;
842 		file->private_data = &ppp->file;
843 		ppp->owner = file;
844 		err = -EFAULT;
845 		if (put_user(ppp->file.index, p))
846 			break;
847 		err = 0;
848 		break;
849 
850 	case PPPIOCATTACH:
851 		/* Attach to an existing ppp unit */
852 		if (get_user(unit, p))
853 			break;
854 		err = -ENXIO;
855 		pn = ppp_pernet(net);
856 		mutex_lock(&pn->all_ppp_mutex);
857 		ppp = ppp_find_unit(pn, unit);
858 		if (ppp) {
859 			atomic_inc(&ppp->file.refcnt);
860 			file->private_data = &ppp->file;
861 			err = 0;
862 		}
863 		mutex_unlock(&pn->all_ppp_mutex);
864 		break;
865 
866 	case PPPIOCATTCHAN:
867 		if (get_user(unit, p))
868 			break;
869 		err = -ENXIO;
870 		pn = ppp_pernet(net);
871 		spin_lock_bh(&pn->all_channels_lock);
872 		chan = ppp_find_channel(pn, unit);
873 		if (chan) {
874 			atomic_inc(&chan->file.refcnt);
875 			file->private_data = &chan->file;
876 			err = 0;
877 		}
878 		spin_unlock_bh(&pn->all_channels_lock);
879 		break;
880 
881 	default:
882 		err = -ENOTTY;
883 	}
884 	mutex_unlock(&ppp_mutex);
885 	return err;
886 }
887 
888 static const struct file_operations ppp_device_fops = {
889 	.owner		= THIS_MODULE,
890 	.read		= ppp_read,
891 	.write		= ppp_write,
892 	.poll		= ppp_poll,
893 	.unlocked_ioctl	= ppp_ioctl,
894 	.open		= ppp_open,
895 	.release	= ppp_release,
896 	.llseek		= noop_llseek,
897 };
898 
899 static __net_init int ppp_init_net(struct net *net)
900 {
901 	struct ppp_net *pn = net_generic(net, ppp_net_id);
902 
903 	idr_init(&pn->units_idr);
904 	mutex_init(&pn->all_ppp_mutex);
905 
906 	INIT_LIST_HEAD(&pn->all_channels);
907 	INIT_LIST_HEAD(&pn->new_channels);
908 
909 	spin_lock_init(&pn->all_channels_lock);
910 
911 	return 0;
912 }
913 
914 static __net_exit void ppp_exit_net(struct net *net)
915 {
916 	struct ppp_net *pn = net_generic(net, ppp_net_id);
917 
918 	idr_destroy(&pn->units_idr);
919 }
920 
921 static struct pernet_operations ppp_net_ops = {
922 	.init = ppp_init_net,
923 	.exit = ppp_exit_net,
924 	.id   = &ppp_net_id,
925 	.size = sizeof(struct ppp_net),
926 };
927 
928 #define PPP_MAJOR	108
929 
930 /* Called at boot time if ppp is compiled into the kernel,
931    or at module load time (from init_module) if compiled as a module. */
932 static int __init ppp_init(void)
933 {
934 	int err;
935 
936 	pr_info("PPP generic driver version " PPP_VERSION "\n");
937 
938 	err = register_pernet_device(&ppp_net_ops);
939 	if (err) {
940 		pr_err("failed to register PPP pernet device (%d)\n", err);
941 		goto out;
942 	}
943 
944 	err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
945 	if (err) {
946 		pr_err("failed to register PPP device (%d)\n", err);
947 		goto out_net;
948 	}
949 
950 	ppp_class = class_create(THIS_MODULE, "ppp");
951 	if (IS_ERR(ppp_class)) {
952 		err = PTR_ERR(ppp_class);
953 		goto out_chrdev;
954 	}
955 
956 	/* not a big deal if we fail here :-) */
957 	device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
958 
959 	return 0;
960 
961 out_chrdev:
962 	unregister_chrdev(PPP_MAJOR, "ppp");
963 out_net:
964 	unregister_pernet_device(&ppp_net_ops);
965 out:
966 	return err;
967 }
968 
969 /*
970  * Network interface unit routines.
971  */
972 static netdev_tx_t
973 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
974 {
975 	struct ppp *ppp = netdev_priv(dev);
976 	int npi, proto;
977 	unsigned char *pp;
978 
979 	npi = ethertype_to_npindex(ntohs(skb->protocol));
980 	if (npi < 0)
981 		goto outf;
982 
983 	/* Drop, accept or reject the packet */
984 	switch (ppp->npmode[npi]) {
985 	case NPMODE_PASS:
986 		break;
987 	case NPMODE_QUEUE:
988 		/* it would be nice to have a way to tell the network
989 		   system to queue this one up for later. */
990 		goto outf;
991 	case NPMODE_DROP:
992 	case NPMODE_ERROR:
993 		goto outf;
994 	}
995 
996 	/* Put the 2-byte PPP protocol number on the front,
997 	   making sure there is room for the address and control fields. */
998 	if (skb_cow_head(skb, PPP_HDRLEN))
999 		goto outf;
1000 
1001 	pp = skb_push(skb, 2);
1002 	proto = npindex_to_proto[npi];
1003 	put_unaligned_be16(proto, pp);
1004 
1005 	skb_queue_tail(&ppp->file.xq, skb);
1006 	ppp_xmit_process(ppp);
1007 	return NETDEV_TX_OK;
1008 
1009  outf:
1010 	kfree_skb(skb);
1011 	++dev->stats.tx_dropped;
1012 	return NETDEV_TX_OK;
1013 }
1014 
1015 static int
1016 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
1017 {
1018 	struct ppp *ppp = netdev_priv(dev);
1019 	int err = -EFAULT;
1020 	void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
1021 	struct ppp_stats stats;
1022 	struct ppp_comp_stats cstats;
1023 	char *vers;
1024 
1025 	switch (cmd) {
1026 	case SIOCGPPPSTATS:
1027 		ppp_get_stats(ppp, &stats);
1028 		if (copy_to_user(addr, &stats, sizeof(stats)))
1029 			break;
1030 		err = 0;
1031 		break;
1032 
1033 	case SIOCGPPPCSTATS:
1034 		memset(&cstats, 0, sizeof(cstats));
1035 		if (ppp->xc_state)
1036 			ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
1037 		if (ppp->rc_state)
1038 			ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
1039 		if (copy_to_user(addr, &cstats, sizeof(cstats)))
1040 			break;
1041 		err = 0;
1042 		break;
1043 
1044 	case SIOCGPPPVER:
1045 		vers = PPP_VERSION;
1046 		if (copy_to_user(addr, vers, strlen(vers) + 1))
1047 			break;
1048 		err = 0;
1049 		break;
1050 
1051 	default:
1052 		err = -EINVAL;
1053 	}
1054 
1055 	return err;
1056 }
1057 
1058 static struct rtnl_link_stats64*
1059 ppp_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats64)
1060 {
1061 	struct ppp *ppp = netdev_priv(dev);
1062 
1063 	ppp_recv_lock(ppp);
1064 	stats64->rx_packets = ppp->stats64.rx_packets;
1065 	stats64->rx_bytes   = ppp->stats64.rx_bytes;
1066 	ppp_recv_unlock(ppp);
1067 
1068 	ppp_xmit_lock(ppp);
1069 	stats64->tx_packets = ppp->stats64.tx_packets;
1070 	stats64->tx_bytes   = ppp->stats64.tx_bytes;
1071 	ppp_xmit_unlock(ppp);
1072 
1073 	stats64->rx_errors        = dev->stats.rx_errors;
1074 	stats64->tx_errors        = dev->stats.tx_errors;
1075 	stats64->rx_dropped       = dev->stats.rx_dropped;
1076 	stats64->tx_dropped       = dev->stats.tx_dropped;
1077 	stats64->rx_length_errors = dev->stats.rx_length_errors;
1078 
1079 	return stats64;
1080 }
1081 
1082 static struct lock_class_key ppp_tx_busylock;
1083 static int ppp_dev_init(struct net_device *dev)
1084 {
1085 	dev->qdisc_tx_busylock = &ppp_tx_busylock;
1086 	return 0;
1087 }
1088 
1089 static const struct net_device_ops ppp_netdev_ops = {
1090 	.ndo_init	 = ppp_dev_init,
1091 	.ndo_start_xmit  = ppp_start_xmit,
1092 	.ndo_do_ioctl    = ppp_net_ioctl,
1093 	.ndo_get_stats64 = ppp_get_stats64,
1094 };
1095 
1096 static void ppp_setup(struct net_device *dev)
1097 {
1098 	dev->netdev_ops = &ppp_netdev_ops;
1099 	dev->hard_header_len = PPP_HDRLEN;
1100 	dev->mtu = PPP_MRU;
1101 	dev->addr_len = 0;
1102 	dev->tx_queue_len = 3;
1103 	dev->type = ARPHRD_PPP;
1104 	dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1105 	dev->features |= NETIF_F_NETNS_LOCAL;
1106 	netif_keep_dst(dev);
1107 }
1108 
1109 /*
1110  * Transmit-side routines.
1111  */
1112 
1113 /*
1114  * Called to do any work queued up on the transmit side
1115  * that can now be done.
1116  */
1117 static void
1118 ppp_xmit_process(struct ppp *ppp)
1119 {
1120 	struct sk_buff *skb;
1121 
1122 	ppp_xmit_lock(ppp);
1123 	if (!ppp->closing) {
1124 		ppp_push(ppp);
1125 		while (!ppp->xmit_pending &&
1126 		       (skb = skb_dequeue(&ppp->file.xq)))
1127 			ppp_send_frame(ppp, skb);
1128 		/* If there's no work left to do, tell the core net
1129 		   code that we can accept some more. */
1130 		if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1131 			netif_wake_queue(ppp->dev);
1132 		else
1133 			netif_stop_queue(ppp->dev);
1134 	}
1135 	ppp_xmit_unlock(ppp);
1136 }
1137 
1138 static inline struct sk_buff *
1139 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1140 {
1141 	struct sk_buff *new_skb;
1142 	int len;
1143 	int new_skb_size = ppp->dev->mtu +
1144 		ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1145 	int compressor_skb_size = ppp->dev->mtu +
1146 		ppp->xcomp->comp_extra + PPP_HDRLEN;
1147 	new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1148 	if (!new_skb) {
1149 		if (net_ratelimit())
1150 			netdev_err(ppp->dev, "PPP: no memory (comp pkt)\n");
1151 		return NULL;
1152 	}
1153 	if (ppp->dev->hard_header_len > PPP_HDRLEN)
1154 		skb_reserve(new_skb,
1155 			    ppp->dev->hard_header_len - PPP_HDRLEN);
1156 
1157 	/* compressor still expects A/C bytes in hdr */
1158 	len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1159 				   new_skb->data, skb->len + 2,
1160 				   compressor_skb_size);
1161 	if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1162 		consume_skb(skb);
1163 		skb = new_skb;
1164 		skb_put(skb, len);
1165 		skb_pull(skb, 2);	/* pull off A/C bytes */
1166 	} else if (len == 0) {
1167 		/* didn't compress, or CCP not up yet */
1168 		consume_skb(new_skb);
1169 		new_skb = skb;
1170 	} else {
1171 		/*
1172 		 * (len < 0)
1173 		 * MPPE requires that we do not send unencrypted
1174 		 * frames.  The compressor will return -1 if we
1175 		 * should drop the frame.  We cannot simply test
1176 		 * the compress_proto because MPPE and MPPC share
1177 		 * the same number.
1178 		 */
1179 		if (net_ratelimit())
1180 			netdev_err(ppp->dev, "ppp: compressor dropped pkt\n");
1181 		kfree_skb(skb);
1182 		consume_skb(new_skb);
1183 		new_skb = NULL;
1184 	}
1185 	return new_skb;
1186 }
1187 
1188 /*
1189  * Compress and send a frame.
1190  * The caller should have locked the xmit path,
1191  * and xmit_pending should be 0.
1192  */
1193 static void
1194 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1195 {
1196 	int proto = PPP_PROTO(skb);
1197 	struct sk_buff *new_skb;
1198 	int len;
1199 	unsigned char *cp;
1200 
1201 	if (proto < 0x8000) {
1202 #ifdef CONFIG_PPP_FILTER
1203 		/* check if we should pass this packet */
1204 		/* the filter instructions are constructed assuming
1205 		   a four-byte PPP header on each packet */
1206 		*skb_push(skb, 2) = 1;
1207 		if (ppp->pass_filter &&
1208 		    BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
1209 			if (ppp->debug & 1)
1210 				netdev_printk(KERN_DEBUG, ppp->dev,
1211 					      "PPP: outbound frame "
1212 					      "not passed\n");
1213 			kfree_skb(skb);
1214 			return;
1215 		}
1216 		/* if this packet passes the active filter, record the time */
1217 		if (!(ppp->active_filter &&
1218 		      BPF_PROG_RUN(ppp->active_filter, skb) == 0))
1219 			ppp->last_xmit = jiffies;
1220 		skb_pull(skb, 2);
1221 #else
1222 		/* for data packets, record the time */
1223 		ppp->last_xmit = jiffies;
1224 #endif /* CONFIG_PPP_FILTER */
1225 	}
1226 
1227 	++ppp->stats64.tx_packets;
1228 	ppp->stats64.tx_bytes += skb->len - 2;
1229 
1230 	switch (proto) {
1231 	case PPP_IP:
1232 		if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1233 			break;
1234 		/* try to do VJ TCP header compression */
1235 		new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1236 				    GFP_ATOMIC);
1237 		if (!new_skb) {
1238 			netdev_err(ppp->dev, "PPP: no memory (VJ comp pkt)\n");
1239 			goto drop;
1240 		}
1241 		skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1242 		cp = skb->data + 2;
1243 		len = slhc_compress(ppp->vj, cp, skb->len - 2,
1244 				    new_skb->data + 2, &cp,
1245 				    !(ppp->flags & SC_NO_TCP_CCID));
1246 		if (cp == skb->data + 2) {
1247 			/* didn't compress */
1248 			consume_skb(new_skb);
1249 		} else {
1250 			if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1251 				proto = PPP_VJC_COMP;
1252 				cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1253 			} else {
1254 				proto = PPP_VJC_UNCOMP;
1255 				cp[0] = skb->data[2];
1256 			}
1257 			consume_skb(skb);
1258 			skb = new_skb;
1259 			cp = skb_put(skb, len + 2);
1260 			cp[0] = 0;
1261 			cp[1] = proto;
1262 		}
1263 		break;
1264 
1265 	case PPP_CCP:
1266 		/* peek at outbound CCP frames */
1267 		ppp_ccp_peek(ppp, skb, 0);
1268 		break;
1269 	}
1270 
1271 	/* try to do packet compression */
1272 	if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state &&
1273 	    proto != PPP_LCP && proto != PPP_CCP) {
1274 		if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1275 			if (net_ratelimit())
1276 				netdev_err(ppp->dev,
1277 					   "ppp: compression required but "
1278 					   "down - pkt dropped.\n");
1279 			goto drop;
1280 		}
1281 		skb = pad_compress_skb(ppp, skb);
1282 		if (!skb)
1283 			goto drop;
1284 	}
1285 
1286 	/*
1287 	 * If we are waiting for traffic (demand dialling),
1288 	 * queue it up for pppd to receive.
1289 	 */
1290 	if (ppp->flags & SC_LOOP_TRAFFIC) {
1291 		if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1292 			goto drop;
1293 		skb_queue_tail(&ppp->file.rq, skb);
1294 		wake_up_interruptible(&ppp->file.rwait);
1295 		return;
1296 	}
1297 
1298 	ppp->xmit_pending = skb;
1299 	ppp_push(ppp);
1300 	return;
1301 
1302  drop:
1303 	kfree_skb(skb);
1304 	++ppp->dev->stats.tx_errors;
1305 }
1306 
1307 /*
1308  * Try to send the frame in xmit_pending.
1309  * The caller should have the xmit path locked.
1310  */
1311 static void
1312 ppp_push(struct ppp *ppp)
1313 {
1314 	struct list_head *list;
1315 	struct channel *pch;
1316 	struct sk_buff *skb = ppp->xmit_pending;
1317 
1318 	if (!skb)
1319 		return;
1320 
1321 	list = &ppp->channels;
1322 	if (list_empty(list)) {
1323 		/* nowhere to send the packet, just drop it */
1324 		ppp->xmit_pending = NULL;
1325 		kfree_skb(skb);
1326 		return;
1327 	}
1328 
1329 	if ((ppp->flags & SC_MULTILINK) == 0) {
1330 		/* not doing multilink: send it down the first channel */
1331 		list = list->next;
1332 		pch = list_entry(list, struct channel, clist);
1333 
1334 		spin_lock_bh(&pch->downl);
1335 		if (pch->chan) {
1336 			if (pch->chan->ops->start_xmit(pch->chan, skb))
1337 				ppp->xmit_pending = NULL;
1338 		} else {
1339 			/* channel got unregistered */
1340 			kfree_skb(skb);
1341 			ppp->xmit_pending = NULL;
1342 		}
1343 		spin_unlock_bh(&pch->downl);
1344 		return;
1345 	}
1346 
1347 #ifdef CONFIG_PPP_MULTILINK
1348 	/* Multilink: fragment the packet over as many links
1349 	   as can take the packet at the moment. */
1350 	if (!ppp_mp_explode(ppp, skb))
1351 		return;
1352 #endif /* CONFIG_PPP_MULTILINK */
1353 
1354 	ppp->xmit_pending = NULL;
1355 	kfree_skb(skb);
1356 }
1357 
1358 #ifdef CONFIG_PPP_MULTILINK
1359 static bool mp_protocol_compress __read_mostly = true;
1360 module_param(mp_protocol_compress, bool, S_IRUGO | S_IWUSR);
1361 MODULE_PARM_DESC(mp_protocol_compress,
1362 		 "compress protocol id in multilink fragments");
1363 
1364 /*
1365  * Divide a packet to be transmitted into fragments and
1366  * send them out the individual links.
1367  */
1368 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1369 {
1370 	int len, totlen;
1371 	int i, bits, hdrlen, mtu;
1372 	int flen;
1373 	int navail, nfree, nzero;
1374 	int nbigger;
1375 	int totspeed;
1376 	int totfree;
1377 	unsigned char *p, *q;
1378 	struct list_head *list;
1379 	struct channel *pch;
1380 	struct sk_buff *frag;
1381 	struct ppp_channel *chan;
1382 
1383 	totspeed = 0; /*total bitrate of the bundle*/
1384 	nfree = 0; /* # channels which have no packet already queued */
1385 	navail = 0; /* total # of usable channels (not deregistered) */
1386 	nzero = 0; /* number of channels with zero speed associated*/
1387 	totfree = 0; /*total # of channels available and
1388 				  *having no queued packets before
1389 				  *starting the fragmentation*/
1390 
1391 	hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1392 	i = 0;
1393 	list_for_each_entry(pch, &ppp->channels, clist) {
1394 		if (pch->chan) {
1395 			pch->avail = 1;
1396 			navail++;
1397 			pch->speed = pch->chan->speed;
1398 		} else {
1399 			pch->avail = 0;
1400 		}
1401 		if (pch->avail) {
1402 			if (skb_queue_empty(&pch->file.xq) ||
1403 				!pch->had_frag) {
1404 					if (pch->speed == 0)
1405 						nzero++;
1406 					else
1407 						totspeed += pch->speed;
1408 
1409 					pch->avail = 2;
1410 					++nfree;
1411 					++totfree;
1412 				}
1413 			if (!pch->had_frag && i < ppp->nxchan)
1414 				ppp->nxchan = i;
1415 		}
1416 		++i;
1417 	}
1418 	/*
1419 	 * Don't start sending this packet unless at least half of
1420 	 * the channels are free.  This gives much better TCP
1421 	 * performance if we have a lot of channels.
1422 	 */
1423 	if (nfree == 0 || nfree < navail / 2)
1424 		return 0; /* can't take now, leave it in xmit_pending */
1425 
1426 	/* Do protocol field compression */
1427 	p = skb->data;
1428 	len = skb->len;
1429 	if (*p == 0 && mp_protocol_compress) {
1430 		++p;
1431 		--len;
1432 	}
1433 
1434 	totlen = len;
1435 	nbigger = len % nfree;
1436 
1437 	/* skip to the channel after the one we last used
1438 	   and start at that one */
1439 	list = &ppp->channels;
1440 	for (i = 0; i < ppp->nxchan; ++i) {
1441 		list = list->next;
1442 		if (list == &ppp->channels) {
1443 			i = 0;
1444 			break;
1445 		}
1446 	}
1447 
1448 	/* create a fragment for each channel */
1449 	bits = B;
1450 	while (len > 0) {
1451 		list = list->next;
1452 		if (list == &ppp->channels) {
1453 			i = 0;
1454 			continue;
1455 		}
1456 		pch = list_entry(list, struct channel, clist);
1457 		++i;
1458 		if (!pch->avail)
1459 			continue;
1460 
1461 		/*
1462 		 * Skip this channel if it has a fragment pending already and
1463 		 * we haven't given a fragment to all of the free channels.
1464 		 */
1465 		if (pch->avail == 1) {
1466 			if (nfree > 0)
1467 				continue;
1468 		} else {
1469 			pch->avail = 1;
1470 		}
1471 
1472 		/* check the channel's mtu and whether it is still attached. */
1473 		spin_lock_bh(&pch->downl);
1474 		if (pch->chan == NULL) {
1475 			/* can't use this channel, it's being deregistered */
1476 			if (pch->speed == 0)
1477 				nzero--;
1478 			else
1479 				totspeed -= pch->speed;
1480 
1481 			spin_unlock_bh(&pch->downl);
1482 			pch->avail = 0;
1483 			totlen = len;
1484 			totfree--;
1485 			nfree--;
1486 			if (--navail == 0)
1487 				break;
1488 			continue;
1489 		}
1490 
1491 		/*
1492 		*if the channel speed is not set divide
1493 		*the packet evenly among the free channels;
1494 		*otherwise divide it according to the speed
1495 		*of the channel we are going to transmit on
1496 		*/
1497 		flen = len;
1498 		if (nfree > 0) {
1499 			if (pch->speed == 0) {
1500 				flen = len/nfree;
1501 				if (nbigger > 0) {
1502 					flen++;
1503 					nbigger--;
1504 				}
1505 			} else {
1506 				flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
1507 					((totspeed*totfree)/pch->speed)) - hdrlen;
1508 				if (nbigger > 0) {
1509 					flen += ((totfree - nzero)*pch->speed)/totspeed;
1510 					nbigger -= ((totfree - nzero)*pch->speed)/
1511 							totspeed;
1512 				}
1513 			}
1514 			nfree--;
1515 		}
1516 
1517 		/*
1518 		 *check if we are on the last channel or
1519 		 *we exceded the length of the data to
1520 		 *fragment
1521 		 */
1522 		if ((nfree <= 0) || (flen > len))
1523 			flen = len;
1524 		/*
1525 		 *it is not worth to tx on slow channels:
1526 		 *in that case from the resulting flen according to the
1527 		 *above formula will be equal or less than zero.
1528 		 *Skip the channel in this case
1529 		 */
1530 		if (flen <= 0) {
1531 			pch->avail = 2;
1532 			spin_unlock_bh(&pch->downl);
1533 			continue;
1534 		}
1535 
1536 		/*
1537 		 * hdrlen includes the 2-byte PPP protocol field, but the
1538 		 * MTU counts only the payload excluding the protocol field.
1539 		 * (RFC1661 Section 2)
1540 		 */
1541 		mtu = pch->chan->mtu - (hdrlen - 2);
1542 		if (mtu < 4)
1543 			mtu = 4;
1544 		if (flen > mtu)
1545 			flen = mtu;
1546 		if (flen == len)
1547 			bits |= E;
1548 		frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1549 		if (!frag)
1550 			goto noskb;
1551 		q = skb_put(frag, flen + hdrlen);
1552 
1553 		/* make the MP header */
1554 		put_unaligned_be16(PPP_MP, q);
1555 		if (ppp->flags & SC_MP_XSHORTSEQ) {
1556 			q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1557 			q[3] = ppp->nxseq;
1558 		} else {
1559 			q[2] = bits;
1560 			q[3] = ppp->nxseq >> 16;
1561 			q[4] = ppp->nxseq >> 8;
1562 			q[5] = ppp->nxseq;
1563 		}
1564 
1565 		memcpy(q + hdrlen, p, flen);
1566 
1567 		/* try to send it down the channel */
1568 		chan = pch->chan;
1569 		if (!skb_queue_empty(&pch->file.xq) ||
1570 			!chan->ops->start_xmit(chan, frag))
1571 			skb_queue_tail(&pch->file.xq, frag);
1572 		pch->had_frag = 1;
1573 		p += flen;
1574 		len -= flen;
1575 		++ppp->nxseq;
1576 		bits = 0;
1577 		spin_unlock_bh(&pch->downl);
1578 	}
1579 	ppp->nxchan = i;
1580 
1581 	return 1;
1582 
1583  noskb:
1584 	spin_unlock_bh(&pch->downl);
1585 	if (ppp->debug & 1)
1586 		netdev_err(ppp->dev, "PPP: no memory (fragment)\n");
1587 	++ppp->dev->stats.tx_errors;
1588 	++ppp->nxseq;
1589 	return 1;	/* abandon the frame */
1590 }
1591 #endif /* CONFIG_PPP_MULTILINK */
1592 
1593 /*
1594  * Try to send data out on a channel.
1595  */
1596 static void
1597 ppp_channel_push(struct channel *pch)
1598 {
1599 	struct sk_buff *skb;
1600 	struct ppp *ppp;
1601 
1602 	spin_lock_bh(&pch->downl);
1603 	if (pch->chan) {
1604 		while (!skb_queue_empty(&pch->file.xq)) {
1605 			skb = skb_dequeue(&pch->file.xq);
1606 			if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1607 				/* put the packet back and try again later */
1608 				skb_queue_head(&pch->file.xq, skb);
1609 				break;
1610 			}
1611 		}
1612 	} else {
1613 		/* channel got deregistered */
1614 		skb_queue_purge(&pch->file.xq);
1615 	}
1616 	spin_unlock_bh(&pch->downl);
1617 	/* see if there is anything from the attached unit to be sent */
1618 	if (skb_queue_empty(&pch->file.xq)) {
1619 		read_lock_bh(&pch->upl);
1620 		ppp = pch->ppp;
1621 		if (ppp)
1622 			ppp_xmit_process(ppp);
1623 		read_unlock_bh(&pch->upl);
1624 	}
1625 }
1626 
1627 /*
1628  * Receive-side routines.
1629  */
1630 
1631 struct ppp_mp_skb_parm {
1632 	u32		sequence;
1633 	u8		BEbits;
1634 };
1635 #define PPP_MP_CB(skb)	((struct ppp_mp_skb_parm *)((skb)->cb))
1636 
1637 static inline void
1638 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1639 {
1640 	ppp_recv_lock(ppp);
1641 	if (!ppp->closing)
1642 		ppp_receive_frame(ppp, skb, pch);
1643 	else
1644 		kfree_skb(skb);
1645 	ppp_recv_unlock(ppp);
1646 }
1647 
1648 void
1649 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1650 {
1651 	struct channel *pch = chan->ppp;
1652 	int proto;
1653 
1654 	if (!pch) {
1655 		kfree_skb(skb);
1656 		return;
1657 	}
1658 
1659 	read_lock_bh(&pch->upl);
1660 	if (!pskb_may_pull(skb, 2)) {
1661 		kfree_skb(skb);
1662 		if (pch->ppp) {
1663 			++pch->ppp->dev->stats.rx_length_errors;
1664 			ppp_receive_error(pch->ppp);
1665 		}
1666 		goto done;
1667 	}
1668 
1669 	proto = PPP_PROTO(skb);
1670 	if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1671 		/* put it on the channel queue */
1672 		skb_queue_tail(&pch->file.rq, skb);
1673 		/* drop old frames if queue too long */
1674 		while (pch->file.rq.qlen > PPP_MAX_RQLEN &&
1675 		       (skb = skb_dequeue(&pch->file.rq)))
1676 			kfree_skb(skb);
1677 		wake_up_interruptible(&pch->file.rwait);
1678 	} else {
1679 		ppp_do_recv(pch->ppp, skb, pch);
1680 	}
1681 
1682 done:
1683 	read_unlock_bh(&pch->upl);
1684 }
1685 
1686 /* Put a 0-length skb in the receive queue as an error indication */
1687 void
1688 ppp_input_error(struct ppp_channel *chan, int code)
1689 {
1690 	struct channel *pch = chan->ppp;
1691 	struct sk_buff *skb;
1692 
1693 	if (!pch)
1694 		return;
1695 
1696 	read_lock_bh(&pch->upl);
1697 	if (pch->ppp) {
1698 		skb = alloc_skb(0, GFP_ATOMIC);
1699 		if (skb) {
1700 			skb->len = 0;		/* probably unnecessary */
1701 			skb->cb[0] = code;
1702 			ppp_do_recv(pch->ppp, skb, pch);
1703 		}
1704 	}
1705 	read_unlock_bh(&pch->upl);
1706 }
1707 
1708 /*
1709  * We come in here to process a received frame.
1710  * The receive side of the ppp unit is locked.
1711  */
1712 static void
1713 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1714 {
1715 	/* note: a 0-length skb is used as an error indication */
1716 	if (skb->len > 0) {
1717 #ifdef CONFIG_PPP_MULTILINK
1718 		/* XXX do channel-level decompression here */
1719 		if (PPP_PROTO(skb) == PPP_MP)
1720 			ppp_receive_mp_frame(ppp, skb, pch);
1721 		else
1722 #endif /* CONFIG_PPP_MULTILINK */
1723 			ppp_receive_nonmp_frame(ppp, skb);
1724 	} else {
1725 		kfree_skb(skb);
1726 		ppp_receive_error(ppp);
1727 	}
1728 }
1729 
1730 static void
1731 ppp_receive_error(struct ppp *ppp)
1732 {
1733 	++ppp->dev->stats.rx_errors;
1734 	if (ppp->vj)
1735 		slhc_toss(ppp->vj);
1736 }
1737 
1738 static void
1739 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1740 {
1741 	struct sk_buff *ns;
1742 	int proto, len, npi;
1743 
1744 	/*
1745 	 * Decompress the frame, if compressed.
1746 	 * Note that some decompressors need to see uncompressed frames
1747 	 * that come in as well as compressed frames.
1748 	 */
1749 	if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN) &&
1750 	    (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1751 		skb = ppp_decompress_frame(ppp, skb);
1752 
1753 	if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1754 		goto err;
1755 
1756 	proto = PPP_PROTO(skb);
1757 	switch (proto) {
1758 	case PPP_VJC_COMP:
1759 		/* decompress VJ compressed packets */
1760 		if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1761 			goto err;
1762 
1763 		if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1764 			/* copy to a new sk_buff with more tailroom */
1765 			ns = dev_alloc_skb(skb->len + 128);
1766 			if (!ns) {
1767 				netdev_err(ppp->dev, "PPP: no memory "
1768 					   "(VJ decomp)\n");
1769 				goto err;
1770 			}
1771 			skb_reserve(ns, 2);
1772 			skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1773 			consume_skb(skb);
1774 			skb = ns;
1775 		}
1776 		else
1777 			skb->ip_summed = CHECKSUM_NONE;
1778 
1779 		len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1780 		if (len <= 0) {
1781 			netdev_printk(KERN_DEBUG, ppp->dev,
1782 				      "PPP: VJ decompression error\n");
1783 			goto err;
1784 		}
1785 		len += 2;
1786 		if (len > skb->len)
1787 			skb_put(skb, len - skb->len);
1788 		else if (len < skb->len)
1789 			skb_trim(skb, len);
1790 		proto = PPP_IP;
1791 		break;
1792 
1793 	case PPP_VJC_UNCOMP:
1794 		if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1795 			goto err;
1796 
1797 		/* Until we fix the decompressor need to make sure
1798 		 * data portion is linear.
1799 		 */
1800 		if (!pskb_may_pull(skb, skb->len))
1801 			goto err;
1802 
1803 		if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1804 			netdev_err(ppp->dev, "PPP: VJ uncompressed error\n");
1805 			goto err;
1806 		}
1807 		proto = PPP_IP;
1808 		break;
1809 
1810 	case PPP_CCP:
1811 		ppp_ccp_peek(ppp, skb, 1);
1812 		break;
1813 	}
1814 
1815 	++ppp->stats64.rx_packets;
1816 	ppp->stats64.rx_bytes += skb->len - 2;
1817 
1818 	npi = proto_to_npindex(proto);
1819 	if (npi < 0) {
1820 		/* control or unknown frame - pass it to pppd */
1821 		skb_queue_tail(&ppp->file.rq, skb);
1822 		/* limit queue length by dropping old frames */
1823 		while (ppp->file.rq.qlen > PPP_MAX_RQLEN &&
1824 		       (skb = skb_dequeue(&ppp->file.rq)))
1825 			kfree_skb(skb);
1826 		/* wake up any process polling or blocking on read */
1827 		wake_up_interruptible(&ppp->file.rwait);
1828 
1829 	} else {
1830 		/* network protocol frame - give it to the kernel */
1831 
1832 #ifdef CONFIG_PPP_FILTER
1833 		/* check if the packet passes the pass and active filters */
1834 		/* the filter instructions are constructed assuming
1835 		   a four-byte PPP header on each packet */
1836 		if (ppp->pass_filter || ppp->active_filter) {
1837 			if (skb_unclone(skb, GFP_ATOMIC))
1838 				goto err;
1839 
1840 			*skb_push(skb, 2) = 0;
1841 			if (ppp->pass_filter &&
1842 			    BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
1843 				if (ppp->debug & 1)
1844 					netdev_printk(KERN_DEBUG, ppp->dev,
1845 						      "PPP: inbound frame "
1846 						      "not passed\n");
1847 				kfree_skb(skb);
1848 				return;
1849 			}
1850 			if (!(ppp->active_filter &&
1851 			      BPF_PROG_RUN(ppp->active_filter, skb) == 0))
1852 				ppp->last_recv = jiffies;
1853 			__skb_pull(skb, 2);
1854 		} else
1855 #endif /* CONFIG_PPP_FILTER */
1856 			ppp->last_recv = jiffies;
1857 
1858 		if ((ppp->dev->flags & IFF_UP) == 0 ||
1859 		    ppp->npmode[npi] != NPMODE_PASS) {
1860 			kfree_skb(skb);
1861 		} else {
1862 			/* chop off protocol */
1863 			skb_pull_rcsum(skb, 2);
1864 			skb->dev = ppp->dev;
1865 			skb->protocol = htons(npindex_to_ethertype[npi]);
1866 			skb_reset_mac_header(skb);
1867 			netif_rx(skb);
1868 		}
1869 	}
1870 	return;
1871 
1872  err:
1873 	kfree_skb(skb);
1874 	ppp_receive_error(ppp);
1875 }
1876 
1877 static struct sk_buff *
1878 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1879 {
1880 	int proto = PPP_PROTO(skb);
1881 	struct sk_buff *ns;
1882 	int len;
1883 
1884 	/* Until we fix all the decompressor's need to make sure
1885 	 * data portion is linear.
1886 	 */
1887 	if (!pskb_may_pull(skb, skb->len))
1888 		goto err;
1889 
1890 	if (proto == PPP_COMP) {
1891 		int obuff_size;
1892 
1893 		switch(ppp->rcomp->compress_proto) {
1894 		case CI_MPPE:
1895 			obuff_size = ppp->mru + PPP_HDRLEN + 1;
1896 			break;
1897 		default:
1898 			obuff_size = ppp->mru + PPP_HDRLEN;
1899 			break;
1900 		}
1901 
1902 		ns = dev_alloc_skb(obuff_size);
1903 		if (!ns) {
1904 			netdev_err(ppp->dev, "ppp_decompress_frame: "
1905 				   "no memory\n");
1906 			goto err;
1907 		}
1908 		/* the decompressor still expects the A/C bytes in the hdr */
1909 		len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1910 				skb->len + 2, ns->data, obuff_size);
1911 		if (len < 0) {
1912 			/* Pass the compressed frame to pppd as an
1913 			   error indication. */
1914 			if (len == DECOMP_FATALERROR)
1915 				ppp->rstate |= SC_DC_FERROR;
1916 			kfree_skb(ns);
1917 			goto err;
1918 		}
1919 
1920 		consume_skb(skb);
1921 		skb = ns;
1922 		skb_put(skb, len);
1923 		skb_pull(skb, 2);	/* pull off the A/C bytes */
1924 
1925 	} else {
1926 		/* Uncompressed frame - pass to decompressor so it
1927 		   can update its dictionary if necessary. */
1928 		if (ppp->rcomp->incomp)
1929 			ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1930 					   skb->len + 2);
1931 	}
1932 
1933 	return skb;
1934 
1935  err:
1936 	ppp->rstate |= SC_DC_ERROR;
1937 	ppp_receive_error(ppp);
1938 	return skb;
1939 }
1940 
1941 #ifdef CONFIG_PPP_MULTILINK
1942 /*
1943  * Receive a multilink frame.
1944  * We put it on the reconstruction queue and then pull off
1945  * as many completed frames as we can.
1946  */
1947 static void
1948 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1949 {
1950 	u32 mask, seq;
1951 	struct channel *ch;
1952 	int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1953 
1954 	if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1955 		goto err;		/* no good, throw it away */
1956 
1957 	/* Decode sequence number and begin/end bits */
1958 	if (ppp->flags & SC_MP_SHORTSEQ) {
1959 		seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1960 		mask = 0xfff;
1961 	} else {
1962 		seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1963 		mask = 0xffffff;
1964 	}
1965 	PPP_MP_CB(skb)->BEbits = skb->data[2];
1966 	skb_pull(skb, mphdrlen);	/* pull off PPP and MP headers */
1967 
1968 	/*
1969 	 * Do protocol ID decompression on the first fragment of each packet.
1970 	 */
1971 	if ((PPP_MP_CB(skb)->BEbits & B) && (skb->data[0] & 1))
1972 		*skb_push(skb, 1) = 0;
1973 
1974 	/*
1975 	 * Expand sequence number to 32 bits, making it as close
1976 	 * as possible to ppp->minseq.
1977 	 */
1978 	seq |= ppp->minseq & ~mask;
1979 	if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1980 		seq += mask + 1;
1981 	else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1982 		seq -= mask + 1;	/* should never happen */
1983 	PPP_MP_CB(skb)->sequence = seq;
1984 	pch->lastseq = seq;
1985 
1986 	/*
1987 	 * If this packet comes before the next one we were expecting,
1988 	 * drop it.
1989 	 */
1990 	if (seq_before(seq, ppp->nextseq)) {
1991 		kfree_skb(skb);
1992 		++ppp->dev->stats.rx_dropped;
1993 		ppp_receive_error(ppp);
1994 		return;
1995 	}
1996 
1997 	/*
1998 	 * Reevaluate minseq, the minimum over all channels of the
1999 	 * last sequence number received on each channel.  Because of
2000 	 * the increasing sequence number rule, we know that any fragment
2001 	 * before `minseq' which hasn't arrived is never going to arrive.
2002 	 * The list of channels can't change because we have the receive
2003 	 * side of the ppp unit locked.
2004 	 */
2005 	list_for_each_entry(ch, &ppp->channels, clist) {
2006 		if (seq_before(ch->lastseq, seq))
2007 			seq = ch->lastseq;
2008 	}
2009 	if (seq_before(ppp->minseq, seq))
2010 		ppp->minseq = seq;
2011 
2012 	/* Put the fragment on the reconstruction queue */
2013 	ppp_mp_insert(ppp, skb);
2014 
2015 	/* If the queue is getting long, don't wait any longer for packets
2016 	   before the start of the queue. */
2017 	if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
2018 		struct sk_buff *mskb = skb_peek(&ppp->mrq);
2019 		if (seq_before(ppp->minseq, PPP_MP_CB(mskb)->sequence))
2020 			ppp->minseq = PPP_MP_CB(mskb)->sequence;
2021 	}
2022 
2023 	/* Pull completed packets off the queue and receive them. */
2024 	while ((skb = ppp_mp_reconstruct(ppp))) {
2025 		if (pskb_may_pull(skb, 2))
2026 			ppp_receive_nonmp_frame(ppp, skb);
2027 		else {
2028 			++ppp->dev->stats.rx_length_errors;
2029 			kfree_skb(skb);
2030 			ppp_receive_error(ppp);
2031 		}
2032 	}
2033 
2034 	return;
2035 
2036  err:
2037 	kfree_skb(skb);
2038 	ppp_receive_error(ppp);
2039 }
2040 
2041 /*
2042  * Insert a fragment on the MP reconstruction queue.
2043  * The queue is ordered by increasing sequence number.
2044  */
2045 static void
2046 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
2047 {
2048 	struct sk_buff *p;
2049 	struct sk_buff_head *list = &ppp->mrq;
2050 	u32 seq = PPP_MP_CB(skb)->sequence;
2051 
2052 	/* N.B. we don't need to lock the list lock because we have the
2053 	   ppp unit receive-side lock. */
2054 	skb_queue_walk(list, p) {
2055 		if (seq_before(seq, PPP_MP_CB(p)->sequence))
2056 			break;
2057 	}
2058 	__skb_queue_before(list, p, skb);
2059 }
2060 
2061 /*
2062  * Reconstruct a packet from the MP fragment queue.
2063  * We go through increasing sequence numbers until we find a
2064  * complete packet, or we get to the sequence number for a fragment
2065  * which hasn't arrived but might still do so.
2066  */
2067 static struct sk_buff *
2068 ppp_mp_reconstruct(struct ppp *ppp)
2069 {
2070 	u32 seq = ppp->nextseq;
2071 	u32 minseq = ppp->minseq;
2072 	struct sk_buff_head *list = &ppp->mrq;
2073 	struct sk_buff *p, *tmp;
2074 	struct sk_buff *head, *tail;
2075 	struct sk_buff *skb = NULL;
2076 	int lost = 0, len = 0;
2077 
2078 	if (ppp->mrru == 0)	/* do nothing until mrru is set */
2079 		return NULL;
2080 	head = list->next;
2081 	tail = NULL;
2082 	skb_queue_walk_safe(list, p, tmp) {
2083 	again:
2084 		if (seq_before(PPP_MP_CB(p)->sequence, seq)) {
2085 			/* this can't happen, anyway ignore the skb */
2086 			netdev_err(ppp->dev, "ppp_mp_reconstruct bad "
2087 				   "seq %u < %u\n",
2088 				   PPP_MP_CB(p)->sequence, seq);
2089 			__skb_unlink(p, list);
2090 			kfree_skb(p);
2091 			continue;
2092 		}
2093 		if (PPP_MP_CB(p)->sequence != seq) {
2094 			u32 oldseq;
2095 			/* Fragment `seq' is missing.  If it is after
2096 			   minseq, it might arrive later, so stop here. */
2097 			if (seq_after(seq, minseq))
2098 				break;
2099 			/* Fragment `seq' is lost, keep going. */
2100 			lost = 1;
2101 			oldseq = seq;
2102 			seq = seq_before(minseq, PPP_MP_CB(p)->sequence)?
2103 				minseq + 1: PPP_MP_CB(p)->sequence;
2104 
2105 			if (ppp->debug & 1)
2106 				netdev_printk(KERN_DEBUG, ppp->dev,
2107 					      "lost frag %u..%u\n",
2108 					      oldseq, seq-1);
2109 
2110 			goto again;
2111 		}
2112 
2113 		/*
2114 		 * At this point we know that all the fragments from
2115 		 * ppp->nextseq to seq are either present or lost.
2116 		 * Also, there are no complete packets in the queue
2117 		 * that have no missing fragments and end before this
2118 		 * fragment.
2119 		 */
2120 
2121 		/* B bit set indicates this fragment starts a packet */
2122 		if (PPP_MP_CB(p)->BEbits & B) {
2123 			head = p;
2124 			lost = 0;
2125 			len = 0;
2126 		}
2127 
2128 		len += p->len;
2129 
2130 		/* Got a complete packet yet? */
2131 		if (lost == 0 && (PPP_MP_CB(p)->BEbits & E) &&
2132 		    (PPP_MP_CB(head)->BEbits & B)) {
2133 			if (len > ppp->mrru + 2) {
2134 				++ppp->dev->stats.rx_length_errors;
2135 				netdev_printk(KERN_DEBUG, ppp->dev,
2136 					      "PPP: reconstructed packet"
2137 					      " is too long (%d)\n", len);
2138 			} else {
2139 				tail = p;
2140 				break;
2141 			}
2142 			ppp->nextseq = seq + 1;
2143 		}
2144 
2145 		/*
2146 		 * If this is the ending fragment of a packet,
2147 		 * and we haven't found a complete valid packet yet,
2148 		 * we can discard up to and including this fragment.
2149 		 */
2150 		if (PPP_MP_CB(p)->BEbits & E) {
2151 			struct sk_buff *tmp2;
2152 
2153 			skb_queue_reverse_walk_from_safe(list, p, tmp2) {
2154 				if (ppp->debug & 1)
2155 					netdev_printk(KERN_DEBUG, ppp->dev,
2156 						      "discarding frag %u\n",
2157 						      PPP_MP_CB(p)->sequence);
2158 				__skb_unlink(p, list);
2159 				kfree_skb(p);
2160 			}
2161 			head = skb_peek(list);
2162 			if (!head)
2163 				break;
2164 		}
2165 		++seq;
2166 	}
2167 
2168 	/* If we have a complete packet, copy it all into one skb. */
2169 	if (tail != NULL) {
2170 		/* If we have discarded any fragments,
2171 		   signal a receive error. */
2172 		if (PPP_MP_CB(head)->sequence != ppp->nextseq) {
2173 			skb_queue_walk_safe(list, p, tmp) {
2174 				if (p == head)
2175 					break;
2176 				if (ppp->debug & 1)
2177 					netdev_printk(KERN_DEBUG, ppp->dev,
2178 						      "discarding frag %u\n",
2179 						      PPP_MP_CB(p)->sequence);
2180 				__skb_unlink(p, list);
2181 				kfree_skb(p);
2182 			}
2183 
2184 			if (ppp->debug & 1)
2185 				netdev_printk(KERN_DEBUG, ppp->dev,
2186 					      "  missed pkts %u..%u\n",
2187 					      ppp->nextseq,
2188 					      PPP_MP_CB(head)->sequence-1);
2189 			++ppp->dev->stats.rx_dropped;
2190 			ppp_receive_error(ppp);
2191 		}
2192 
2193 		skb = head;
2194 		if (head != tail) {
2195 			struct sk_buff **fragpp = &skb_shinfo(skb)->frag_list;
2196 			p = skb_queue_next(list, head);
2197 			__skb_unlink(skb, list);
2198 			skb_queue_walk_from_safe(list, p, tmp) {
2199 				__skb_unlink(p, list);
2200 				*fragpp = p;
2201 				p->next = NULL;
2202 				fragpp = &p->next;
2203 
2204 				skb->len += p->len;
2205 				skb->data_len += p->len;
2206 				skb->truesize += p->truesize;
2207 
2208 				if (p == tail)
2209 					break;
2210 			}
2211 		} else {
2212 			__skb_unlink(skb, list);
2213 		}
2214 
2215 		ppp->nextseq = PPP_MP_CB(tail)->sequence + 1;
2216 	}
2217 
2218 	return skb;
2219 }
2220 #endif /* CONFIG_PPP_MULTILINK */
2221 
2222 /*
2223  * Channel interface.
2224  */
2225 
2226 /* Create a new, unattached ppp channel. */
2227 int ppp_register_channel(struct ppp_channel *chan)
2228 {
2229 	return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2230 }
2231 
2232 /* Create a new, unattached ppp channel for specified net. */
2233 int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2234 {
2235 	struct channel *pch;
2236 	struct ppp_net *pn;
2237 
2238 	pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2239 	if (!pch)
2240 		return -ENOMEM;
2241 
2242 	pn = ppp_pernet(net);
2243 
2244 	pch->ppp = NULL;
2245 	pch->chan = chan;
2246 	pch->chan_net = net;
2247 	chan->ppp = pch;
2248 	init_ppp_file(&pch->file, CHANNEL);
2249 	pch->file.hdrlen = chan->hdrlen;
2250 #ifdef CONFIG_PPP_MULTILINK
2251 	pch->lastseq = -1;
2252 #endif /* CONFIG_PPP_MULTILINK */
2253 	init_rwsem(&pch->chan_sem);
2254 	spin_lock_init(&pch->downl);
2255 	rwlock_init(&pch->upl);
2256 
2257 	spin_lock_bh(&pn->all_channels_lock);
2258 	pch->file.index = ++pn->last_channel_index;
2259 	list_add(&pch->list, &pn->new_channels);
2260 	atomic_inc(&channel_count);
2261 	spin_unlock_bh(&pn->all_channels_lock);
2262 
2263 	return 0;
2264 }
2265 
2266 /*
2267  * Return the index of a channel.
2268  */
2269 int ppp_channel_index(struct ppp_channel *chan)
2270 {
2271 	struct channel *pch = chan->ppp;
2272 
2273 	if (pch)
2274 		return pch->file.index;
2275 	return -1;
2276 }
2277 
2278 /*
2279  * Return the PPP unit number to which a channel is connected.
2280  */
2281 int ppp_unit_number(struct ppp_channel *chan)
2282 {
2283 	struct channel *pch = chan->ppp;
2284 	int unit = -1;
2285 
2286 	if (pch) {
2287 		read_lock_bh(&pch->upl);
2288 		if (pch->ppp)
2289 			unit = pch->ppp->file.index;
2290 		read_unlock_bh(&pch->upl);
2291 	}
2292 	return unit;
2293 }
2294 
2295 /*
2296  * Return the PPP device interface name of a channel.
2297  */
2298 char *ppp_dev_name(struct ppp_channel *chan)
2299 {
2300 	struct channel *pch = chan->ppp;
2301 	char *name = NULL;
2302 
2303 	if (pch) {
2304 		read_lock_bh(&pch->upl);
2305 		if (pch->ppp && pch->ppp->dev)
2306 			name = pch->ppp->dev->name;
2307 		read_unlock_bh(&pch->upl);
2308 	}
2309 	return name;
2310 }
2311 
2312 
2313 /*
2314  * Disconnect a channel from the generic layer.
2315  * This must be called in process context.
2316  */
2317 void
2318 ppp_unregister_channel(struct ppp_channel *chan)
2319 {
2320 	struct channel *pch = chan->ppp;
2321 	struct ppp_net *pn;
2322 
2323 	if (!pch)
2324 		return;		/* should never happen */
2325 
2326 	chan->ppp = NULL;
2327 
2328 	/*
2329 	 * This ensures that we have returned from any calls into the
2330 	 * the channel's start_xmit or ioctl routine before we proceed.
2331 	 */
2332 	down_write(&pch->chan_sem);
2333 	spin_lock_bh(&pch->downl);
2334 	pch->chan = NULL;
2335 	spin_unlock_bh(&pch->downl);
2336 	up_write(&pch->chan_sem);
2337 	ppp_disconnect_channel(pch);
2338 
2339 	pn = ppp_pernet(pch->chan_net);
2340 	spin_lock_bh(&pn->all_channels_lock);
2341 	list_del(&pch->list);
2342 	spin_unlock_bh(&pn->all_channels_lock);
2343 
2344 	pch->file.dead = 1;
2345 	wake_up_interruptible(&pch->file.rwait);
2346 	if (atomic_dec_and_test(&pch->file.refcnt))
2347 		ppp_destroy_channel(pch);
2348 }
2349 
2350 /*
2351  * Callback from a channel when it can accept more to transmit.
2352  * This should be called at BH/softirq level, not interrupt level.
2353  */
2354 void
2355 ppp_output_wakeup(struct ppp_channel *chan)
2356 {
2357 	struct channel *pch = chan->ppp;
2358 
2359 	if (!pch)
2360 		return;
2361 	ppp_channel_push(pch);
2362 }
2363 
2364 /*
2365  * Compression control.
2366  */
2367 
2368 /* Process the PPPIOCSCOMPRESS ioctl. */
2369 static int
2370 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2371 {
2372 	int err;
2373 	struct compressor *cp, *ocomp;
2374 	struct ppp_option_data data;
2375 	void *state, *ostate;
2376 	unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2377 
2378 	err = -EFAULT;
2379 	if (copy_from_user(&data, (void __user *) arg, sizeof(data)) ||
2380 	    (data.length <= CCP_MAX_OPTION_LENGTH &&
2381 	     copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2382 		goto out;
2383 	err = -EINVAL;
2384 	if (data.length > CCP_MAX_OPTION_LENGTH ||
2385 	    ccp_option[1] < 2 || ccp_option[1] > data.length)
2386 		goto out;
2387 
2388 	cp = try_then_request_module(
2389 		find_compressor(ccp_option[0]),
2390 		"ppp-compress-%d", ccp_option[0]);
2391 	if (!cp)
2392 		goto out;
2393 
2394 	err = -ENOBUFS;
2395 	if (data.transmit) {
2396 		state = cp->comp_alloc(ccp_option, data.length);
2397 		if (state) {
2398 			ppp_xmit_lock(ppp);
2399 			ppp->xstate &= ~SC_COMP_RUN;
2400 			ocomp = ppp->xcomp;
2401 			ostate = ppp->xc_state;
2402 			ppp->xcomp = cp;
2403 			ppp->xc_state = state;
2404 			ppp_xmit_unlock(ppp);
2405 			if (ostate) {
2406 				ocomp->comp_free(ostate);
2407 				module_put(ocomp->owner);
2408 			}
2409 			err = 0;
2410 		} else
2411 			module_put(cp->owner);
2412 
2413 	} else {
2414 		state = cp->decomp_alloc(ccp_option, data.length);
2415 		if (state) {
2416 			ppp_recv_lock(ppp);
2417 			ppp->rstate &= ~SC_DECOMP_RUN;
2418 			ocomp = ppp->rcomp;
2419 			ostate = ppp->rc_state;
2420 			ppp->rcomp = cp;
2421 			ppp->rc_state = state;
2422 			ppp_recv_unlock(ppp);
2423 			if (ostate) {
2424 				ocomp->decomp_free(ostate);
2425 				module_put(ocomp->owner);
2426 			}
2427 			err = 0;
2428 		} else
2429 			module_put(cp->owner);
2430 	}
2431 
2432  out:
2433 	return err;
2434 }
2435 
2436 /*
2437  * Look at a CCP packet and update our state accordingly.
2438  * We assume the caller has the xmit or recv path locked.
2439  */
2440 static void
2441 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2442 {
2443 	unsigned char *dp;
2444 	int len;
2445 
2446 	if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2447 		return;	/* no header */
2448 	dp = skb->data + 2;
2449 
2450 	switch (CCP_CODE(dp)) {
2451 	case CCP_CONFREQ:
2452 
2453 		/* A ConfReq starts negotiation of compression
2454 		 * in one direction of transmission,
2455 		 * and hence brings it down...but which way?
2456 		 *
2457 		 * Remember:
2458 		 * A ConfReq indicates what the sender would like to receive
2459 		 */
2460 		if(inbound)
2461 			/* He is proposing what I should send */
2462 			ppp->xstate &= ~SC_COMP_RUN;
2463 		else
2464 			/* I am proposing to what he should send */
2465 			ppp->rstate &= ~SC_DECOMP_RUN;
2466 
2467 		break;
2468 
2469 	case CCP_TERMREQ:
2470 	case CCP_TERMACK:
2471 		/*
2472 		 * CCP is going down, both directions of transmission
2473 		 */
2474 		ppp->rstate &= ~SC_DECOMP_RUN;
2475 		ppp->xstate &= ~SC_COMP_RUN;
2476 		break;
2477 
2478 	case CCP_CONFACK:
2479 		if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2480 			break;
2481 		len = CCP_LENGTH(dp);
2482 		if (!pskb_may_pull(skb, len + 2))
2483 			return;		/* too short */
2484 		dp += CCP_HDRLEN;
2485 		len -= CCP_HDRLEN;
2486 		if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2487 			break;
2488 		if (inbound) {
2489 			/* we will start receiving compressed packets */
2490 			if (!ppp->rc_state)
2491 				break;
2492 			if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2493 					ppp->file.index, 0, ppp->mru, ppp->debug)) {
2494 				ppp->rstate |= SC_DECOMP_RUN;
2495 				ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2496 			}
2497 		} else {
2498 			/* we will soon start sending compressed packets */
2499 			if (!ppp->xc_state)
2500 				break;
2501 			if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2502 					ppp->file.index, 0, ppp->debug))
2503 				ppp->xstate |= SC_COMP_RUN;
2504 		}
2505 		break;
2506 
2507 	case CCP_RESETACK:
2508 		/* reset the [de]compressor */
2509 		if ((ppp->flags & SC_CCP_UP) == 0)
2510 			break;
2511 		if (inbound) {
2512 			if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2513 				ppp->rcomp->decomp_reset(ppp->rc_state);
2514 				ppp->rstate &= ~SC_DC_ERROR;
2515 			}
2516 		} else {
2517 			if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2518 				ppp->xcomp->comp_reset(ppp->xc_state);
2519 		}
2520 		break;
2521 	}
2522 }
2523 
2524 /* Free up compression resources. */
2525 static void
2526 ppp_ccp_closed(struct ppp *ppp)
2527 {
2528 	void *xstate, *rstate;
2529 	struct compressor *xcomp, *rcomp;
2530 
2531 	ppp_lock(ppp);
2532 	ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2533 	ppp->xstate = 0;
2534 	xcomp = ppp->xcomp;
2535 	xstate = ppp->xc_state;
2536 	ppp->xc_state = NULL;
2537 	ppp->rstate = 0;
2538 	rcomp = ppp->rcomp;
2539 	rstate = ppp->rc_state;
2540 	ppp->rc_state = NULL;
2541 	ppp_unlock(ppp);
2542 
2543 	if (xstate) {
2544 		xcomp->comp_free(xstate);
2545 		module_put(xcomp->owner);
2546 	}
2547 	if (rstate) {
2548 		rcomp->decomp_free(rstate);
2549 		module_put(rcomp->owner);
2550 	}
2551 }
2552 
2553 /* List of compressors. */
2554 static LIST_HEAD(compressor_list);
2555 static DEFINE_SPINLOCK(compressor_list_lock);
2556 
2557 struct compressor_entry {
2558 	struct list_head list;
2559 	struct compressor *comp;
2560 };
2561 
2562 static struct compressor_entry *
2563 find_comp_entry(int proto)
2564 {
2565 	struct compressor_entry *ce;
2566 
2567 	list_for_each_entry(ce, &compressor_list, list) {
2568 		if (ce->comp->compress_proto == proto)
2569 			return ce;
2570 	}
2571 	return NULL;
2572 }
2573 
2574 /* Register a compressor */
2575 int
2576 ppp_register_compressor(struct compressor *cp)
2577 {
2578 	struct compressor_entry *ce;
2579 	int ret;
2580 	spin_lock(&compressor_list_lock);
2581 	ret = -EEXIST;
2582 	if (find_comp_entry(cp->compress_proto))
2583 		goto out;
2584 	ret = -ENOMEM;
2585 	ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2586 	if (!ce)
2587 		goto out;
2588 	ret = 0;
2589 	ce->comp = cp;
2590 	list_add(&ce->list, &compressor_list);
2591  out:
2592 	spin_unlock(&compressor_list_lock);
2593 	return ret;
2594 }
2595 
2596 /* Unregister a compressor */
2597 void
2598 ppp_unregister_compressor(struct compressor *cp)
2599 {
2600 	struct compressor_entry *ce;
2601 
2602 	spin_lock(&compressor_list_lock);
2603 	ce = find_comp_entry(cp->compress_proto);
2604 	if (ce && ce->comp == cp) {
2605 		list_del(&ce->list);
2606 		kfree(ce);
2607 	}
2608 	spin_unlock(&compressor_list_lock);
2609 }
2610 
2611 /* Find a compressor. */
2612 static struct compressor *
2613 find_compressor(int type)
2614 {
2615 	struct compressor_entry *ce;
2616 	struct compressor *cp = NULL;
2617 
2618 	spin_lock(&compressor_list_lock);
2619 	ce = find_comp_entry(type);
2620 	if (ce) {
2621 		cp = ce->comp;
2622 		if (!try_module_get(cp->owner))
2623 			cp = NULL;
2624 	}
2625 	spin_unlock(&compressor_list_lock);
2626 	return cp;
2627 }
2628 
2629 /*
2630  * Miscelleneous stuff.
2631  */
2632 
2633 static void
2634 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2635 {
2636 	struct slcompress *vj = ppp->vj;
2637 
2638 	memset(st, 0, sizeof(*st));
2639 	st->p.ppp_ipackets = ppp->stats64.rx_packets;
2640 	st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2641 	st->p.ppp_ibytes = ppp->stats64.rx_bytes;
2642 	st->p.ppp_opackets = ppp->stats64.tx_packets;
2643 	st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2644 	st->p.ppp_obytes = ppp->stats64.tx_bytes;
2645 	if (!vj)
2646 		return;
2647 	st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2648 	st->vj.vjs_compressed = vj->sls_o_compressed;
2649 	st->vj.vjs_searches = vj->sls_o_searches;
2650 	st->vj.vjs_misses = vj->sls_o_misses;
2651 	st->vj.vjs_errorin = vj->sls_i_error;
2652 	st->vj.vjs_tossed = vj->sls_i_tossed;
2653 	st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2654 	st->vj.vjs_compressedin = vj->sls_i_compressed;
2655 }
2656 
2657 /*
2658  * Stuff for handling the lists of ppp units and channels
2659  * and for initialization.
2660  */
2661 
2662 /*
2663  * Create a new ppp interface unit.  Fails if it can't allocate memory
2664  * or if there is already a unit with the requested number.
2665  * unit == -1 means allocate a new number.
2666  */
2667 static struct ppp *
2668 ppp_create_interface(struct net *net, int unit, int *retp)
2669 {
2670 	struct ppp *ppp;
2671 	struct ppp_net *pn;
2672 	struct net_device *dev = NULL;
2673 	int ret = -ENOMEM;
2674 	int i;
2675 
2676 	dev = alloc_netdev(sizeof(struct ppp), "", NET_NAME_UNKNOWN,
2677 			   ppp_setup);
2678 	if (!dev)
2679 		goto out1;
2680 
2681 	pn = ppp_pernet(net);
2682 
2683 	ppp = netdev_priv(dev);
2684 	ppp->dev = dev;
2685 	ppp->mru = PPP_MRU;
2686 	init_ppp_file(&ppp->file, INTERFACE);
2687 	ppp->file.hdrlen = PPP_HDRLEN - 2;	/* don't count proto bytes */
2688 	for (i = 0; i < NUM_NP; ++i)
2689 		ppp->npmode[i] = NPMODE_PASS;
2690 	INIT_LIST_HEAD(&ppp->channels);
2691 	spin_lock_init(&ppp->rlock);
2692 	spin_lock_init(&ppp->wlock);
2693 #ifdef CONFIG_PPP_MULTILINK
2694 	ppp->minseq = -1;
2695 	skb_queue_head_init(&ppp->mrq);
2696 #endif /* CONFIG_PPP_MULTILINK */
2697 #ifdef CONFIG_PPP_FILTER
2698 	ppp->pass_filter = NULL;
2699 	ppp->active_filter = NULL;
2700 #endif /* CONFIG_PPP_FILTER */
2701 
2702 	/*
2703 	 * drum roll: don't forget to set
2704 	 * the net device is belong to
2705 	 */
2706 	dev_net_set(dev, net);
2707 
2708 	mutex_lock(&pn->all_ppp_mutex);
2709 
2710 	if (unit < 0) {
2711 		unit = unit_get(&pn->units_idr, ppp);
2712 		if (unit < 0) {
2713 			ret = unit;
2714 			goto out2;
2715 		}
2716 	} else {
2717 		ret = -EEXIST;
2718 		if (unit_find(&pn->units_idr, unit))
2719 			goto out2; /* unit already exists */
2720 		/*
2721 		 * if caller need a specified unit number
2722 		 * lets try to satisfy him, otherwise --
2723 		 * he should better ask us for new unit number
2724 		 *
2725 		 * NOTE: yes I know that returning EEXIST it's not
2726 		 * fair but at least pppd will ask us to allocate
2727 		 * new unit in this case so user is happy :)
2728 		 */
2729 		unit = unit_set(&pn->units_idr, ppp, unit);
2730 		if (unit < 0)
2731 			goto out2;
2732 	}
2733 
2734 	/* Initialize the new ppp unit */
2735 	ppp->file.index = unit;
2736 	sprintf(dev->name, "ppp%d", unit);
2737 
2738 	ret = register_netdev(dev);
2739 	if (ret != 0) {
2740 		unit_put(&pn->units_idr, unit);
2741 		netdev_err(ppp->dev, "PPP: couldn't register device %s (%d)\n",
2742 			   dev->name, ret);
2743 		goto out2;
2744 	}
2745 
2746 	ppp->ppp_net = net;
2747 
2748 	atomic_inc(&ppp_unit_count);
2749 	mutex_unlock(&pn->all_ppp_mutex);
2750 
2751 	*retp = 0;
2752 	return ppp;
2753 
2754 out2:
2755 	mutex_unlock(&pn->all_ppp_mutex);
2756 	free_netdev(dev);
2757 out1:
2758 	*retp = ret;
2759 	return NULL;
2760 }
2761 
2762 /*
2763  * Initialize a ppp_file structure.
2764  */
2765 static void
2766 init_ppp_file(struct ppp_file *pf, int kind)
2767 {
2768 	pf->kind = kind;
2769 	skb_queue_head_init(&pf->xq);
2770 	skb_queue_head_init(&pf->rq);
2771 	atomic_set(&pf->refcnt, 1);
2772 	init_waitqueue_head(&pf->rwait);
2773 }
2774 
2775 /*
2776  * Take down a ppp interface unit - called when the owning file
2777  * (the one that created the unit) is closed or detached.
2778  */
2779 static void ppp_shutdown_interface(struct ppp *ppp)
2780 {
2781 	struct ppp_net *pn;
2782 
2783 	pn = ppp_pernet(ppp->ppp_net);
2784 	mutex_lock(&pn->all_ppp_mutex);
2785 
2786 	/* This will call dev_close() for us. */
2787 	ppp_lock(ppp);
2788 	if (!ppp->closing) {
2789 		ppp->closing = 1;
2790 		ppp_unlock(ppp);
2791 		unregister_netdev(ppp->dev);
2792 		unit_put(&pn->units_idr, ppp->file.index);
2793 	} else
2794 		ppp_unlock(ppp);
2795 
2796 	ppp->file.dead = 1;
2797 	ppp->owner = NULL;
2798 	wake_up_interruptible(&ppp->file.rwait);
2799 
2800 	mutex_unlock(&pn->all_ppp_mutex);
2801 }
2802 
2803 /*
2804  * Free the memory used by a ppp unit.  This is only called once
2805  * there are no channels connected to the unit and no file structs
2806  * that reference the unit.
2807  */
2808 static void ppp_destroy_interface(struct ppp *ppp)
2809 {
2810 	atomic_dec(&ppp_unit_count);
2811 
2812 	if (!ppp->file.dead || ppp->n_channels) {
2813 		/* "can't happen" */
2814 		netdev_err(ppp->dev, "ppp: destroying ppp struct %p "
2815 			   "but dead=%d n_channels=%d !\n",
2816 			   ppp, ppp->file.dead, ppp->n_channels);
2817 		return;
2818 	}
2819 
2820 	ppp_ccp_closed(ppp);
2821 	if (ppp->vj) {
2822 		slhc_free(ppp->vj);
2823 		ppp->vj = NULL;
2824 	}
2825 	skb_queue_purge(&ppp->file.xq);
2826 	skb_queue_purge(&ppp->file.rq);
2827 #ifdef CONFIG_PPP_MULTILINK
2828 	skb_queue_purge(&ppp->mrq);
2829 #endif /* CONFIG_PPP_MULTILINK */
2830 #ifdef CONFIG_PPP_FILTER
2831 	if (ppp->pass_filter) {
2832 		bpf_prog_destroy(ppp->pass_filter);
2833 		ppp->pass_filter = NULL;
2834 	}
2835 
2836 	if (ppp->active_filter) {
2837 		bpf_prog_destroy(ppp->active_filter);
2838 		ppp->active_filter = NULL;
2839 	}
2840 #endif /* CONFIG_PPP_FILTER */
2841 
2842 	kfree_skb(ppp->xmit_pending);
2843 
2844 	free_netdev(ppp->dev);
2845 }
2846 
2847 /*
2848  * Locate an existing ppp unit.
2849  * The caller should have locked the all_ppp_mutex.
2850  */
2851 static struct ppp *
2852 ppp_find_unit(struct ppp_net *pn, int unit)
2853 {
2854 	return unit_find(&pn->units_idr, unit);
2855 }
2856 
2857 /*
2858  * Locate an existing ppp channel.
2859  * The caller should have locked the all_channels_lock.
2860  * First we look in the new_channels list, then in the
2861  * all_channels list.  If found in the new_channels list,
2862  * we move it to the all_channels list.  This is for speed
2863  * when we have a lot of channels in use.
2864  */
2865 static struct channel *
2866 ppp_find_channel(struct ppp_net *pn, int unit)
2867 {
2868 	struct channel *pch;
2869 
2870 	list_for_each_entry(pch, &pn->new_channels, list) {
2871 		if (pch->file.index == unit) {
2872 			list_move(&pch->list, &pn->all_channels);
2873 			return pch;
2874 		}
2875 	}
2876 
2877 	list_for_each_entry(pch, &pn->all_channels, list) {
2878 		if (pch->file.index == unit)
2879 			return pch;
2880 	}
2881 
2882 	return NULL;
2883 }
2884 
2885 /*
2886  * Connect a PPP channel to a PPP interface unit.
2887  */
2888 static int
2889 ppp_connect_channel(struct channel *pch, int unit)
2890 {
2891 	struct ppp *ppp;
2892 	struct ppp_net *pn;
2893 	int ret = -ENXIO;
2894 	int hdrlen;
2895 
2896 	pn = ppp_pernet(pch->chan_net);
2897 
2898 	mutex_lock(&pn->all_ppp_mutex);
2899 	ppp = ppp_find_unit(pn, unit);
2900 	if (!ppp)
2901 		goto out;
2902 	write_lock_bh(&pch->upl);
2903 	ret = -EINVAL;
2904 	if (pch->ppp)
2905 		goto outl;
2906 
2907 	ppp_lock(ppp);
2908 	if (pch->file.hdrlen > ppp->file.hdrlen)
2909 		ppp->file.hdrlen = pch->file.hdrlen;
2910 	hdrlen = pch->file.hdrlen + 2;	/* for protocol bytes */
2911 	if (hdrlen > ppp->dev->hard_header_len)
2912 		ppp->dev->hard_header_len = hdrlen;
2913 	list_add_tail(&pch->clist, &ppp->channels);
2914 	++ppp->n_channels;
2915 	pch->ppp = ppp;
2916 	atomic_inc(&ppp->file.refcnt);
2917 	ppp_unlock(ppp);
2918 	ret = 0;
2919 
2920  outl:
2921 	write_unlock_bh(&pch->upl);
2922  out:
2923 	mutex_unlock(&pn->all_ppp_mutex);
2924 	return ret;
2925 }
2926 
2927 /*
2928  * Disconnect a channel from its ppp unit.
2929  */
2930 static int
2931 ppp_disconnect_channel(struct channel *pch)
2932 {
2933 	struct ppp *ppp;
2934 	int err = -EINVAL;
2935 
2936 	write_lock_bh(&pch->upl);
2937 	ppp = pch->ppp;
2938 	pch->ppp = NULL;
2939 	write_unlock_bh(&pch->upl);
2940 	if (ppp) {
2941 		/* remove it from the ppp unit's list */
2942 		ppp_lock(ppp);
2943 		list_del(&pch->clist);
2944 		if (--ppp->n_channels == 0)
2945 			wake_up_interruptible(&ppp->file.rwait);
2946 		ppp_unlock(ppp);
2947 		if (atomic_dec_and_test(&ppp->file.refcnt))
2948 			ppp_destroy_interface(ppp);
2949 		err = 0;
2950 	}
2951 	return err;
2952 }
2953 
2954 /*
2955  * Free up the resources used by a ppp channel.
2956  */
2957 static void ppp_destroy_channel(struct channel *pch)
2958 {
2959 	atomic_dec(&channel_count);
2960 
2961 	if (!pch->file.dead) {
2962 		/* "can't happen" */
2963 		pr_err("ppp: destroying undead channel %p !\n", pch);
2964 		return;
2965 	}
2966 	skb_queue_purge(&pch->file.xq);
2967 	skb_queue_purge(&pch->file.rq);
2968 	kfree(pch);
2969 }
2970 
2971 static void __exit ppp_cleanup(void)
2972 {
2973 	/* should never happen */
2974 	if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2975 		pr_err("PPP: removing module but units remain!\n");
2976 	unregister_chrdev(PPP_MAJOR, "ppp");
2977 	device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2978 	class_destroy(ppp_class);
2979 	unregister_pernet_device(&ppp_net_ops);
2980 }
2981 
2982 /*
2983  * Units handling. Caller must protect concurrent access
2984  * by holding all_ppp_mutex
2985  */
2986 
2987 /* associate pointer with specified number */
2988 static int unit_set(struct idr *p, void *ptr, int n)
2989 {
2990 	int unit;
2991 
2992 	unit = idr_alloc(p, ptr, n, n + 1, GFP_KERNEL);
2993 	if (unit == -ENOSPC)
2994 		unit = -EINVAL;
2995 	return unit;
2996 }
2997 
2998 /* get new free unit number and associate pointer with it */
2999 static int unit_get(struct idr *p, void *ptr)
3000 {
3001 	return idr_alloc(p, ptr, 0, 0, GFP_KERNEL);
3002 }
3003 
3004 /* put unit number back to a pool */
3005 static void unit_put(struct idr *p, int n)
3006 {
3007 	idr_remove(p, n);
3008 }
3009 
3010 /* get pointer associated with the number */
3011 static void *unit_find(struct idr *p, int n)
3012 {
3013 	return idr_find(p, n);
3014 }
3015 
3016 /* Module/initialization stuff */
3017 
3018 module_init(ppp_init);
3019 module_exit(ppp_cleanup);
3020 
3021 EXPORT_SYMBOL(ppp_register_net_channel);
3022 EXPORT_SYMBOL(ppp_register_channel);
3023 EXPORT_SYMBOL(ppp_unregister_channel);
3024 EXPORT_SYMBOL(ppp_channel_index);
3025 EXPORT_SYMBOL(ppp_unit_number);
3026 EXPORT_SYMBOL(ppp_dev_name);
3027 EXPORT_SYMBOL(ppp_input);
3028 EXPORT_SYMBOL(ppp_input_error);
3029 EXPORT_SYMBOL(ppp_output_wakeup);
3030 EXPORT_SYMBOL(ppp_register_compressor);
3031 EXPORT_SYMBOL(ppp_unregister_compressor);
3032 MODULE_LICENSE("GPL");
3033 MODULE_ALIAS_CHARDEV(PPP_MAJOR, 0);
3034 MODULE_ALIAS("devname:ppp");
3035