1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Generic PPP layer for Linux.
4 *
5 * Copyright 1999-2002 Paul Mackerras.
6 *
7 * The generic PPP layer handles the PPP network interfaces, the
8 * /dev/ppp device, packet and VJ compression, and multilink.
9 * It talks to PPP `channels' via the interface defined in
10 * include/linux/ppp_channel.h.  Channels provide the basic means for
11 * sending and receiving PPP frames on some kind of communications
12 * channel.
13 *
14 * Part of the code in this driver was inspired by the old async-only
15 * PPP driver, written by Michael Callahan and Al Longyear, and
16 * subsequently hacked by Paul Mackerras.
17 *
18 * ==FILEVERSION 20041108==
19 */
20
21#include <linux/module.h>
22#include <linux/kernel.h>
23#include <linux/sched/signal.h>
24#include <linux/kmod.h>
25#include <linux/init.h>
26#include <linux/list.h>
27#include <linux/idr.h>
28#include <linux/netdevice.h>
29#include <linux/poll.h>
30#include <linux/ppp_defs.h>
31#include <linux/filter.h>
32#include <linux/ppp-ioctl.h>
33#include <linux/ppp_channel.h>
34#include <linux/ppp-comp.h>
35#include <linux/skbuff.h>
36#include <linux/rtnetlink.h>
37#include <linux/if_arp.h>
38#include <linux/ip.h>
39#include <linux/tcp.h>
40#include <linux/spinlock.h>
41#include <linux/rwsem.h>
42#include <linux/stddef.h>
43#include <linux/device.h>
44#include <linux/mutex.h>
45#include <linux/slab.h>
46#include <linux/file.h>
47#include <asm/unaligned.h>
48#include <net/slhc_vj.h>
49#include <linux/atomic.h>
50#include <linux/refcount.h>
51
52#include <linux/nsproxy.h>
53#include <net/net_namespace.h>
54#include <net/netns/generic.h>
55
56#define PPP_VERSION	"2.4.2"
57
58/*
59 * Network protocols we support.
60 */
61#define NP_IP	0		/* Internet Protocol V4 */
62#define NP_IPV6	1		/* Internet Protocol V6 */
63#define NP_IPX	2		/* IPX protocol */
64#define NP_AT	3		/* Appletalk protocol */
65#define NP_MPLS_UC 4		/* MPLS unicast */
66#define NP_MPLS_MC 5		/* MPLS multicast */
67#define NUM_NP	6		/* Number of NPs. */
68
69#define MPHDRLEN	6	/* multilink protocol header length */
70#define MPHDRLEN_SSN	4	/* ditto with short sequence numbers */
71
72#define PPP_PROTO_LEN	2
73
74/*
75 * An instance of /dev/ppp can be associated with either a ppp
76 * interface unit or a ppp channel.  In both cases, file->private_data
77 * points to one of these.
78 */
79struct ppp_file {
80	enum {
81		INTERFACE=1, CHANNEL
82	}		kind;
83	struct sk_buff_head xq;		/* pppd transmit queue */
84	struct sk_buff_head rq;		/* receive queue for pppd */
85	wait_queue_head_t rwait;	/* for poll on reading /dev/ppp */
86	refcount_t	refcnt;		/* # refs (incl /dev/ppp attached) */
87	int		hdrlen;		/* space to leave for headers */
88	int		index;		/* interface unit / channel number */
89	int		dead;		/* unit/channel has been shut down */
90};
91
92#define PF_TO_X(pf, X)		container_of(pf, X, file)
93
94#define PF_TO_PPP(pf)		PF_TO_X(pf, struct ppp)
95#define PF_TO_CHANNEL(pf)	PF_TO_X(pf, struct channel)
96
97/*
98 * Data structure to hold primary network stats for which
99 * we want to use 64 bit storage.  Other network stats
100 * are stored in dev->stats of the ppp strucute.
101 */
102struct ppp_link_stats {
103	u64 rx_packets;
104	u64 tx_packets;
105	u64 rx_bytes;
106	u64 tx_bytes;
107};
108
109/*
110 * Data structure describing one ppp unit.
111 * A ppp unit corresponds to a ppp network interface device
112 * and represents a multilink bundle.
113 * It can have 0 or more ppp channels connected to it.
114 */
115struct ppp {
116	struct ppp_file	file;		/* stuff for read/write/poll 0 */
117	struct file	*owner;		/* file that owns this unit 48 */
118	struct list_head channels;	/* list of attached channels 4c */
119	int		n_channels;	/* how many channels are attached 54 */
120	spinlock_t	rlock;		/* lock for receive side 58 */
121	spinlock_t	wlock;		/* lock for transmit side 5c */
122	int __percpu	*xmit_recursion; /* xmit recursion detect */
123	int		mru;		/* max receive unit 60 */
124	unsigned int	flags;		/* control bits 64 */
125	unsigned int	xstate;		/* transmit state bits 68 */
126	unsigned int	rstate;		/* receive state bits 6c */
127	int		debug;		/* debug flags 70 */
128	struct slcompress *vj;		/* state for VJ header compression */
129	enum NPmode	npmode[NUM_NP];	/* what to do with each net proto 78 */
130	struct sk_buff	*xmit_pending;	/* a packet ready to go out 88 */
131	struct compressor *xcomp;	/* transmit packet compressor 8c */
132	void		*xc_state;	/* its internal state 90 */
133	struct compressor *rcomp;	/* receive decompressor 94 */
134	void		*rc_state;	/* its internal state 98 */
135	unsigned long	last_xmit;	/* jiffies when last pkt sent 9c */
136	unsigned long	last_recv;	/* jiffies when last pkt rcvd a0 */
137	struct net_device *dev;		/* network interface device a4 */
138	int		closing;	/* is device closing down? a8 */
139#ifdef CONFIG_PPP_MULTILINK
140	int		nxchan;		/* next channel to send something on */
141	u32		nxseq;		/* next sequence number to send */
142	int		mrru;		/* MP: max reconst. receive unit */
143	u32		nextseq;	/* MP: seq no of next packet */
144	u32		minseq;		/* MP: min of most recent seqnos */
145	struct sk_buff_head mrq;	/* MP: receive reconstruction queue */
146#endif /* CONFIG_PPP_MULTILINK */
147#ifdef CONFIG_PPP_FILTER
148	struct bpf_prog *pass_filter;	/* filter for packets to pass */
149	struct bpf_prog *active_filter; /* filter for pkts to reset idle */
150#endif /* CONFIG_PPP_FILTER */
151	struct net	*ppp_net;	/* the net we belong to */
152	struct ppp_link_stats stats64;	/* 64 bit network stats */
153};
154
155/*
156 * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
157 * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
158 * SC_MUST_COMP
159 * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
160 * Bits in xstate: SC_COMP_RUN
161 */
162#define SC_FLAG_BITS	(SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
163			 |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
164			 |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
165
166/*
167 * Private data structure for each channel.
168 * This includes the data structure used for multilink.
169 */
170struct channel {
171	struct ppp_file	file;		/* stuff for read/write/poll */
172	struct list_head list;		/* link in all/new_channels list */
173	struct ppp_channel *chan;	/* public channel data structure */
174	struct rw_semaphore chan_sem;	/* protects `chan' during chan ioctl */
175	spinlock_t	downl;		/* protects `chan', file.xq dequeue */
176	struct ppp	*ppp;		/* ppp unit we're connected to */
177	struct net	*chan_net;	/* the net channel belongs to */
178	netns_tracker	ns_tracker;
179	struct list_head clist;		/* link in list of channels per unit */
180	rwlock_t	upl;		/* protects `ppp' and 'bridge' */
181	struct channel __rcu *bridge;	/* "bridged" ppp channel */
182#ifdef CONFIG_PPP_MULTILINK
183	u8		avail;		/* flag used in multilink stuff */
184	u8		had_frag;	/* >= 1 fragments have been sent */
185	u32		lastseq;	/* MP: last sequence # received */
186	int		speed;		/* speed of the corresponding ppp channel*/
187#endif /* CONFIG_PPP_MULTILINK */
188};
189
190struct ppp_config {
191	struct file *file;
192	s32 unit;
193	bool ifname_is_set;
194};
195
196/*
197 * SMP locking issues:
198 * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
199 * list and the ppp.n_channels field, you need to take both locks
200 * before you modify them.
201 * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
202 * channel.downl.
203 */
204
205static DEFINE_MUTEX(ppp_mutex);
206static atomic_t ppp_unit_count = ATOMIC_INIT(0);
207static atomic_t channel_count = ATOMIC_INIT(0);
208
209/* per-net private data for this module */
210static unsigned int ppp_net_id __read_mostly;
211struct ppp_net {
212	/* units to ppp mapping */
213	struct idr units_idr;
214
215	/*
216	 * all_ppp_mutex protects the units_idr mapping.
217	 * It also ensures that finding a ppp unit in the units_idr
218	 * map and updating its file.refcnt field is atomic.
219	 */
220	struct mutex all_ppp_mutex;
221
222	/* channels */
223	struct list_head all_channels;
224	struct list_head new_channels;
225	int last_channel_index;
226
227	/*
228	 * all_channels_lock protects all_channels and
229	 * last_channel_index, and the atomicity of find
230	 * a channel and updating its file.refcnt field.
231	 */
232	spinlock_t all_channels_lock;
233};
234
235/* Get the PPP protocol number from a skb */
236#define PPP_PROTO(skb)	get_unaligned_be16((skb)->data)
237
238/* We limit the length of ppp->file.rq to this (arbitrary) value */
239#define PPP_MAX_RQLEN	32
240
241/*
242 * Maximum number of multilink fragments queued up.
243 * This has to be large enough to cope with the maximum latency of
244 * the slowest channel relative to the others.  Strictly it should
245 * depend on the number of channels and their characteristics.
246 */
247#define PPP_MP_MAX_QLEN	128
248
249/* Multilink header bits. */
250#define B	0x80		/* this fragment begins a packet */
251#define E	0x40		/* this fragment ends a packet */
252
253/* Compare multilink sequence numbers (assumed to be 32 bits wide) */
254#define seq_before(a, b)	((s32)((a) - (b)) < 0)
255#define seq_after(a, b)		((s32)((a) - (b)) > 0)
256
257/* Prototypes. */
258static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
259			struct file *file, unsigned int cmd, unsigned long arg);
260static void ppp_xmit_process(struct ppp *ppp, struct sk_buff *skb);
261static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
262static void ppp_push(struct ppp *ppp);
263static void ppp_channel_push(struct channel *pch);
264static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
265			      struct channel *pch);
266static void ppp_receive_error(struct ppp *ppp);
267static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
268static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
269					    struct sk_buff *skb);
270#ifdef CONFIG_PPP_MULTILINK
271static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
272				struct channel *pch);
273static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
274static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
275static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
276#endif /* CONFIG_PPP_MULTILINK */
277static int ppp_set_compress(struct ppp *ppp, struct ppp_option_data *data);
278static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
279static void ppp_ccp_closed(struct ppp *ppp);
280static struct compressor *find_compressor(int type);
281static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
282static int ppp_create_interface(struct net *net, struct file *file, int *unit);
283static void init_ppp_file(struct ppp_file *pf, int kind);
284static void ppp_destroy_interface(struct ppp *ppp);
285static struct ppp *ppp_find_unit(struct ppp_net *pn, int unit);
286static struct channel *ppp_find_channel(struct ppp_net *pn, int unit);
287static int ppp_connect_channel(struct channel *pch, int unit);
288static int ppp_disconnect_channel(struct channel *pch);
289static void ppp_destroy_channel(struct channel *pch);
290static int unit_get(struct idr *p, void *ptr, int min);
291static int unit_set(struct idr *p, void *ptr, int n);
292static void unit_put(struct idr *p, int n);
293static void *unit_find(struct idr *p, int n);
294static void ppp_setup(struct net_device *dev);
295
296static const struct net_device_ops ppp_netdev_ops;
297
298static const struct class ppp_class = {
299	.name = "ppp",
300};
301
302/* per net-namespace data */
303static inline struct ppp_net *ppp_pernet(struct net *net)
304{
305	return net_generic(net, ppp_net_id);
306}
307
308/* Translates a PPP protocol number to a NP index (NP == network protocol) */
309static inline int proto_to_npindex(int proto)
310{
311	switch (proto) {
312	case PPP_IP:
313		return NP_IP;
314	case PPP_IPV6:
315		return NP_IPV6;
316	case PPP_IPX:
317		return NP_IPX;
318	case PPP_AT:
319		return NP_AT;
320	case PPP_MPLS_UC:
321		return NP_MPLS_UC;
322	case PPP_MPLS_MC:
323		return NP_MPLS_MC;
324	}
325	return -EINVAL;
326}
327
328/* Translates an NP index into a PPP protocol number */
329static const int npindex_to_proto[NUM_NP] = {
330	PPP_IP,
331	PPP_IPV6,
332	PPP_IPX,
333	PPP_AT,
334	PPP_MPLS_UC,
335	PPP_MPLS_MC,
336};
337
338/* Translates an ethertype into an NP index */
339static inline int ethertype_to_npindex(int ethertype)
340{
341	switch (ethertype) {
342	case ETH_P_IP:
343		return NP_IP;
344	case ETH_P_IPV6:
345		return NP_IPV6;
346	case ETH_P_IPX:
347		return NP_IPX;
348	case ETH_P_PPPTALK:
349	case ETH_P_ATALK:
350		return NP_AT;
351	case ETH_P_MPLS_UC:
352		return NP_MPLS_UC;
353	case ETH_P_MPLS_MC:
354		return NP_MPLS_MC;
355	}
356	return -1;
357}
358
359/* Translates an NP index into an ethertype */
360static const int npindex_to_ethertype[NUM_NP] = {
361	ETH_P_IP,
362	ETH_P_IPV6,
363	ETH_P_IPX,
364	ETH_P_PPPTALK,
365	ETH_P_MPLS_UC,
366	ETH_P_MPLS_MC,
367};
368
369/*
370 * Locking shorthand.
371 */
372#define ppp_xmit_lock(ppp)	spin_lock_bh(&(ppp)->wlock)
373#define ppp_xmit_unlock(ppp)	spin_unlock_bh(&(ppp)->wlock)
374#define ppp_recv_lock(ppp)	spin_lock_bh(&(ppp)->rlock)
375#define ppp_recv_unlock(ppp)	spin_unlock_bh(&(ppp)->rlock)
376#define ppp_lock(ppp)		do { ppp_xmit_lock(ppp); \
377				     ppp_recv_lock(ppp); } while (0)
378#define ppp_unlock(ppp)		do { ppp_recv_unlock(ppp); \
379				     ppp_xmit_unlock(ppp); } while (0)
380
381/*
382 * /dev/ppp device routines.
383 * The /dev/ppp device is used by pppd to control the ppp unit.
384 * It supports the read, write, ioctl and poll functions.
385 * Open instances of /dev/ppp can be in one of three states:
386 * unattached, attached to a ppp unit, or attached to a ppp channel.
387 */
388static int ppp_open(struct inode *inode, struct file *file)
389{
390	/*
391	 * This could (should?) be enforced by the permissions on /dev/ppp.
392	 */
393	if (!ns_capable(file->f_cred->user_ns, CAP_NET_ADMIN))
394		return -EPERM;
395	return 0;
396}
397
398static int ppp_release(struct inode *unused, struct file *file)
399{
400	struct ppp_file *pf = file->private_data;
401	struct ppp *ppp;
402
403	if (pf) {
404		file->private_data = NULL;
405		if (pf->kind == INTERFACE) {
406			ppp = PF_TO_PPP(pf);
407			rtnl_lock();
408			if (file == ppp->owner)
409				unregister_netdevice(ppp->dev);
410			rtnl_unlock();
411		}
412		if (refcount_dec_and_test(&pf->refcnt)) {
413			switch (pf->kind) {
414			case INTERFACE:
415				ppp_destroy_interface(PF_TO_PPP(pf));
416				break;
417			case CHANNEL:
418				ppp_destroy_channel(PF_TO_CHANNEL(pf));
419				break;
420			}
421		}
422	}
423	return 0;
424}
425
426static ssize_t ppp_read(struct file *file, char __user *buf,
427			size_t count, loff_t *ppos)
428{
429	struct ppp_file *pf = file->private_data;
430	DECLARE_WAITQUEUE(wait, current);
431	ssize_t ret;
432	struct sk_buff *skb = NULL;
433	struct iovec iov;
434	struct iov_iter to;
435
436	ret = count;
437
438	if (!pf)
439		return -ENXIO;
440	add_wait_queue(&pf->rwait, &wait);
441	for (;;) {
442		set_current_state(TASK_INTERRUPTIBLE);
443		skb = skb_dequeue(&pf->rq);
444		if (skb)
445			break;
446		ret = 0;
447		if (pf->dead)
448			break;
449		if (pf->kind == INTERFACE) {
450			/*
451			 * Return 0 (EOF) on an interface that has no
452			 * channels connected, unless it is looping
453			 * network traffic (demand mode).
454			 */
455			struct ppp *ppp = PF_TO_PPP(pf);
456
457			ppp_recv_lock(ppp);
458			if (ppp->n_channels == 0 &&
459			    (ppp->flags & SC_LOOP_TRAFFIC) == 0) {
460				ppp_recv_unlock(ppp);
461				break;
462			}
463			ppp_recv_unlock(ppp);
464		}
465		ret = -EAGAIN;
466		if (file->f_flags & O_NONBLOCK)
467			break;
468		ret = -ERESTARTSYS;
469		if (signal_pending(current))
470			break;
471		schedule();
472	}
473	set_current_state(TASK_RUNNING);
474	remove_wait_queue(&pf->rwait, &wait);
475
476	if (!skb)
477		goto out;
478
479	ret = -EOVERFLOW;
480	if (skb->len > count)
481		goto outf;
482	ret = -EFAULT;
483	iov.iov_base = buf;
484	iov.iov_len = count;
485	iov_iter_init(&to, ITER_DEST, &iov, 1, count);
486	if (skb_copy_datagram_iter(skb, 0, &to, skb->len))
487		goto outf;
488	ret = skb->len;
489
490 outf:
491	kfree_skb(skb);
492 out:
493	return ret;
494}
495
496static ssize_t ppp_write(struct file *file, const char __user *buf,
497			 size_t count, loff_t *ppos)
498{
499	struct ppp_file *pf = file->private_data;
500	struct sk_buff *skb;
501	ssize_t ret;
502
503	if (!pf)
504		return -ENXIO;
505	/* All PPP packets should start with the 2-byte protocol */
506	if (count < PPP_PROTO_LEN)
507		return -EINVAL;
508	ret = -ENOMEM;
509	skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
510	if (!skb)
511		goto out;
512	skb_reserve(skb, pf->hdrlen);
513	ret = -EFAULT;
514	if (copy_from_user(skb_put(skb, count), buf, count)) {
515		kfree_skb(skb);
516		goto out;
517	}
518
519	switch (pf->kind) {
520	case INTERFACE:
521		ppp_xmit_process(PF_TO_PPP(pf), skb);
522		break;
523	case CHANNEL:
524		skb_queue_tail(&pf->xq, skb);
525		ppp_channel_push(PF_TO_CHANNEL(pf));
526		break;
527	}
528
529	ret = count;
530
531 out:
532	return ret;
533}
534
535/* No kernel lock - fine */
536static __poll_t ppp_poll(struct file *file, poll_table *wait)
537{
538	struct ppp_file *pf = file->private_data;
539	__poll_t mask;
540
541	if (!pf)
542		return 0;
543	poll_wait(file, &pf->rwait, wait);
544	mask = EPOLLOUT | EPOLLWRNORM;
545	if (skb_peek(&pf->rq))
546		mask |= EPOLLIN | EPOLLRDNORM;
547	if (pf->dead)
548		mask |= EPOLLHUP;
549	else if (pf->kind == INTERFACE) {
550		/* see comment in ppp_read */
551		struct ppp *ppp = PF_TO_PPP(pf);
552
553		ppp_recv_lock(ppp);
554		if (ppp->n_channels == 0 &&
555		    (ppp->flags & SC_LOOP_TRAFFIC) == 0)
556			mask |= EPOLLIN | EPOLLRDNORM;
557		ppp_recv_unlock(ppp);
558	}
559
560	return mask;
561}
562
563#ifdef CONFIG_PPP_FILTER
564static struct bpf_prog *get_filter(struct sock_fprog *uprog)
565{
566	struct sock_fprog_kern fprog;
567	struct bpf_prog *res = NULL;
568	int err;
569
570	if (!uprog->len)
571		return NULL;
572
573	/* uprog->len is unsigned short, so no overflow here */
574	fprog.len = uprog->len;
575	fprog.filter = memdup_array_user(uprog->filter,
576					 uprog->len, sizeof(struct sock_filter));
577	if (IS_ERR(fprog.filter))
578		return ERR_CAST(fprog.filter);
579
580	err = bpf_prog_create(&res, &fprog);
581	kfree(fprog.filter);
582
583	return err ? ERR_PTR(err) : res;
584}
585
586static struct bpf_prog *ppp_get_filter(struct sock_fprog __user *p)
587{
588	struct sock_fprog uprog;
589
590	if (copy_from_user(&uprog, p, sizeof(struct sock_fprog)))
591		return ERR_PTR(-EFAULT);
592	return get_filter(&uprog);
593}
594
595#ifdef CONFIG_COMPAT
596struct sock_fprog32 {
597	unsigned short len;
598	compat_caddr_t filter;
599};
600
601#define PPPIOCSPASS32		_IOW('t', 71, struct sock_fprog32)
602#define PPPIOCSACTIVE32		_IOW('t', 70, struct sock_fprog32)
603
604static struct bpf_prog *compat_ppp_get_filter(struct sock_fprog32 __user *p)
605{
606	struct sock_fprog32 uprog32;
607	struct sock_fprog uprog;
608
609	if (copy_from_user(&uprog32, p, sizeof(struct sock_fprog32)))
610		return ERR_PTR(-EFAULT);
611	uprog.len = uprog32.len;
612	uprog.filter = compat_ptr(uprog32.filter);
613	return get_filter(&uprog);
614}
615#endif
616#endif
617
618/* Bridge one PPP channel to another.
619 * When two channels are bridged, ppp_input on one channel is redirected to
620 * the other's ops->start_xmit handler.
621 * In order to safely bridge channels we must reject channels which are already
622 * part of a bridge instance, or which form part of an existing unit.
623 * Once successfully bridged, each channel holds a reference on the other
624 * to prevent it being freed while the bridge is extant.
625 */
626static int ppp_bridge_channels(struct channel *pch, struct channel *pchb)
627{
628	write_lock_bh(&pch->upl);
629	if (pch->ppp ||
630	    rcu_dereference_protected(pch->bridge, lockdep_is_held(&pch->upl))) {
631		write_unlock_bh(&pch->upl);
632		return -EALREADY;
633	}
634	refcount_inc(&pchb->file.refcnt);
635	rcu_assign_pointer(pch->bridge, pchb);
636	write_unlock_bh(&pch->upl);
637
638	write_lock_bh(&pchb->upl);
639	if (pchb->ppp ||
640	    rcu_dereference_protected(pchb->bridge, lockdep_is_held(&pchb->upl))) {
641		write_unlock_bh(&pchb->upl);
642		goto err_unset;
643	}
644	refcount_inc(&pch->file.refcnt);
645	rcu_assign_pointer(pchb->bridge, pch);
646	write_unlock_bh(&pchb->upl);
647
648	return 0;
649
650err_unset:
651	write_lock_bh(&pch->upl);
652	/* Re-read pch->bridge with upl held in case it was modified concurrently */
653	pchb = rcu_dereference_protected(pch->bridge, lockdep_is_held(&pch->upl));
654	RCU_INIT_POINTER(pch->bridge, NULL);
655	write_unlock_bh(&pch->upl);
656	synchronize_rcu();
657
658	if (pchb)
659		if (refcount_dec_and_test(&pchb->file.refcnt))
660			ppp_destroy_channel(pchb);
661
662	return -EALREADY;
663}
664
665static int ppp_unbridge_channels(struct channel *pch)
666{
667	struct channel *pchb, *pchbb;
668
669	write_lock_bh(&pch->upl);
670	pchb = rcu_dereference_protected(pch->bridge, lockdep_is_held(&pch->upl));
671	if (!pchb) {
672		write_unlock_bh(&pch->upl);
673		return -EINVAL;
674	}
675	RCU_INIT_POINTER(pch->bridge, NULL);
676	write_unlock_bh(&pch->upl);
677
678	/* Only modify pchb if phcb->bridge points back to pch.
679	 * If not, it implies that there has been a race unbridging (and possibly
680	 * even rebridging) pchb.  We should leave pchb alone to avoid either a
681	 * refcount underflow, or breaking another established bridge instance.
682	 */
683	write_lock_bh(&pchb->upl);
684	pchbb = rcu_dereference_protected(pchb->bridge, lockdep_is_held(&pchb->upl));
685	if (pchbb == pch)
686		RCU_INIT_POINTER(pchb->bridge, NULL);
687	write_unlock_bh(&pchb->upl);
688
689	synchronize_rcu();
690
691	if (pchbb == pch)
692		if (refcount_dec_and_test(&pch->file.refcnt))
693			ppp_destroy_channel(pch);
694
695	if (refcount_dec_and_test(&pchb->file.refcnt))
696		ppp_destroy_channel(pchb);
697
698	return 0;
699}
700
701static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
702{
703	struct ppp_file *pf;
704	struct ppp *ppp;
705	int err = -EFAULT, val, val2, i;
706	struct ppp_idle32 idle32;
707	struct ppp_idle64 idle64;
708	struct npioctl npi;
709	int unit, cflags;
710	struct slcompress *vj;
711	void __user *argp = (void __user *)arg;
712	int __user *p = argp;
713
714	mutex_lock(&ppp_mutex);
715
716	pf = file->private_data;
717	if (!pf) {
718		err = ppp_unattached_ioctl(current->nsproxy->net_ns,
719					   pf, file, cmd, arg);
720		goto out;
721	}
722
723	if (cmd == PPPIOCDETACH) {
724		/*
725		 * PPPIOCDETACH is no longer supported as it was heavily broken,
726		 * and is only known to have been used by pppd older than
727		 * ppp-2.4.2 (released November 2003).
728		 */
729		pr_warn_once("%s (%d) used obsolete PPPIOCDETACH ioctl\n",
730			     current->comm, current->pid);
731		err = -EINVAL;
732		goto out;
733	}
734
735	if (pf->kind == CHANNEL) {
736		struct channel *pch, *pchb;
737		struct ppp_channel *chan;
738		struct ppp_net *pn;
739
740		pch = PF_TO_CHANNEL(pf);
741
742		switch (cmd) {
743		case PPPIOCCONNECT:
744			if (get_user(unit, p))
745				break;
746			err = ppp_connect_channel(pch, unit);
747			break;
748
749		case PPPIOCDISCONN:
750			err = ppp_disconnect_channel(pch);
751			break;
752
753		case PPPIOCBRIDGECHAN:
754			if (get_user(unit, p))
755				break;
756			err = -ENXIO;
757			pn = ppp_pernet(current->nsproxy->net_ns);
758			spin_lock_bh(&pn->all_channels_lock);
759			pchb = ppp_find_channel(pn, unit);
760			/* Hold a reference to prevent pchb being freed while
761			 * we establish the bridge.
762			 */
763			if (pchb)
764				refcount_inc(&pchb->file.refcnt);
765			spin_unlock_bh(&pn->all_channels_lock);
766			if (!pchb)
767				break;
768			err = ppp_bridge_channels(pch, pchb);
769			/* Drop earlier refcount now bridge establishment is complete */
770			if (refcount_dec_and_test(&pchb->file.refcnt))
771				ppp_destroy_channel(pchb);
772			break;
773
774		case PPPIOCUNBRIDGECHAN:
775			err = ppp_unbridge_channels(pch);
776			break;
777
778		default:
779			down_read(&pch->chan_sem);
780			chan = pch->chan;
781			err = -ENOTTY;
782			if (chan && chan->ops->ioctl)
783				err = chan->ops->ioctl(chan, cmd, arg);
784			up_read(&pch->chan_sem);
785		}
786		goto out;
787	}
788
789	if (pf->kind != INTERFACE) {
790		/* can't happen */
791		pr_err("PPP: not interface or channel??\n");
792		err = -EINVAL;
793		goto out;
794	}
795
796	ppp = PF_TO_PPP(pf);
797	switch (cmd) {
798	case PPPIOCSMRU:
799		if (get_user(val, p))
800			break;
801		ppp->mru = val;
802		err = 0;
803		break;
804
805	case PPPIOCSFLAGS:
806		if (get_user(val, p))
807			break;
808		ppp_lock(ppp);
809		cflags = ppp->flags & ~val;
810#ifdef CONFIG_PPP_MULTILINK
811		if (!(ppp->flags & SC_MULTILINK) && (val & SC_MULTILINK))
812			ppp->nextseq = 0;
813#endif
814		ppp->flags = val & SC_FLAG_BITS;
815		ppp_unlock(ppp);
816		if (cflags & SC_CCP_OPEN)
817			ppp_ccp_closed(ppp);
818		err = 0;
819		break;
820
821	case PPPIOCGFLAGS:
822		val = ppp->flags | ppp->xstate | ppp->rstate;
823		if (put_user(val, p))
824			break;
825		err = 0;
826		break;
827
828	case PPPIOCSCOMPRESS:
829	{
830		struct ppp_option_data data;
831		if (copy_from_user(&data, argp, sizeof(data)))
832			err = -EFAULT;
833		else
834			err = ppp_set_compress(ppp, &data);
835		break;
836	}
837	case PPPIOCGUNIT:
838		if (put_user(ppp->file.index, p))
839			break;
840		err = 0;
841		break;
842
843	case PPPIOCSDEBUG:
844		if (get_user(val, p))
845			break;
846		ppp->debug = val;
847		err = 0;
848		break;
849
850	case PPPIOCGDEBUG:
851		if (put_user(ppp->debug, p))
852			break;
853		err = 0;
854		break;
855
856	case PPPIOCGIDLE32:
857                idle32.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
858                idle32.recv_idle = (jiffies - ppp->last_recv) / HZ;
859                if (copy_to_user(argp, &idle32, sizeof(idle32)))
860			break;
861		err = 0;
862		break;
863
864	case PPPIOCGIDLE64:
865		idle64.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
866		idle64.recv_idle = (jiffies - ppp->last_recv) / HZ;
867		if (copy_to_user(argp, &idle64, sizeof(idle64)))
868			break;
869		err = 0;
870		break;
871
872	case PPPIOCSMAXCID:
873		if (get_user(val, p))
874			break;
875		val2 = 15;
876		if ((val >> 16) != 0) {
877			val2 = val >> 16;
878			val &= 0xffff;
879		}
880		vj = slhc_init(val2+1, val+1);
881		if (IS_ERR(vj)) {
882			err = PTR_ERR(vj);
883			break;
884		}
885		ppp_lock(ppp);
886		if (ppp->vj)
887			slhc_free(ppp->vj);
888		ppp->vj = vj;
889		ppp_unlock(ppp);
890		err = 0;
891		break;
892
893	case PPPIOCGNPMODE:
894	case PPPIOCSNPMODE:
895		if (copy_from_user(&npi, argp, sizeof(npi)))
896			break;
897		err = proto_to_npindex(npi.protocol);
898		if (err < 0)
899			break;
900		i = err;
901		if (cmd == PPPIOCGNPMODE) {
902			err = -EFAULT;
903			npi.mode = ppp->npmode[i];
904			if (copy_to_user(argp, &npi, sizeof(npi)))
905				break;
906		} else {
907			ppp->npmode[i] = npi.mode;
908			/* we may be able to transmit more packets now (??) */
909			netif_wake_queue(ppp->dev);
910		}
911		err = 0;
912		break;
913
914#ifdef CONFIG_PPP_FILTER
915	case PPPIOCSPASS:
916	case PPPIOCSACTIVE:
917	{
918		struct bpf_prog *filter = ppp_get_filter(argp);
919		struct bpf_prog **which;
920
921		if (IS_ERR(filter)) {
922			err = PTR_ERR(filter);
923			break;
924		}
925		if (cmd == PPPIOCSPASS)
926			which = &ppp->pass_filter;
927		else
928			which = &ppp->active_filter;
929		ppp_lock(ppp);
930		if (*which)
931			bpf_prog_destroy(*which);
932		*which = filter;
933		ppp_unlock(ppp);
934		err = 0;
935		break;
936	}
937#endif /* CONFIG_PPP_FILTER */
938
939#ifdef CONFIG_PPP_MULTILINK
940	case PPPIOCSMRRU:
941		if (get_user(val, p))
942			break;
943		ppp_recv_lock(ppp);
944		ppp->mrru = val;
945		ppp_recv_unlock(ppp);
946		err = 0;
947		break;
948#endif /* CONFIG_PPP_MULTILINK */
949
950	default:
951		err = -ENOTTY;
952	}
953
954out:
955	mutex_unlock(&ppp_mutex);
956
957	return err;
958}
959
960#ifdef CONFIG_COMPAT
961struct ppp_option_data32 {
962	compat_uptr_t		ptr;
963	u32			length;
964	compat_int_t		transmit;
965};
966#define PPPIOCSCOMPRESS32	_IOW('t', 77, struct ppp_option_data32)
967
968static long ppp_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
969{
970	struct ppp_file *pf;
971	int err = -ENOIOCTLCMD;
972	void __user *argp = (void __user *)arg;
973
974	mutex_lock(&ppp_mutex);
975
976	pf = file->private_data;
977	if (pf && pf->kind == INTERFACE) {
978		struct ppp *ppp = PF_TO_PPP(pf);
979		switch (cmd) {
980#ifdef CONFIG_PPP_FILTER
981		case PPPIOCSPASS32:
982		case PPPIOCSACTIVE32:
983		{
984			struct bpf_prog *filter = compat_ppp_get_filter(argp);
985			struct bpf_prog **which;
986
987			if (IS_ERR(filter)) {
988				err = PTR_ERR(filter);
989				break;
990			}
991			if (cmd == PPPIOCSPASS32)
992				which = &ppp->pass_filter;
993			else
994				which = &ppp->active_filter;
995			ppp_lock(ppp);
996			if (*which)
997				bpf_prog_destroy(*which);
998			*which = filter;
999			ppp_unlock(ppp);
1000			err = 0;
1001			break;
1002		}
1003#endif /* CONFIG_PPP_FILTER */
1004		case PPPIOCSCOMPRESS32:
1005		{
1006			struct ppp_option_data32 data32;
1007			if (copy_from_user(&data32, argp, sizeof(data32))) {
1008				err = -EFAULT;
1009			} else {
1010				struct ppp_option_data data = {
1011					.ptr = compat_ptr(data32.ptr),
1012					.length = data32.length,
1013					.transmit = data32.transmit
1014				};
1015				err = ppp_set_compress(ppp, &data);
1016			}
1017			break;
1018		}
1019		}
1020	}
1021	mutex_unlock(&ppp_mutex);
1022
1023	/* all other commands have compatible arguments */
1024	if (err == -ENOIOCTLCMD)
1025		err = ppp_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
1026
1027	return err;
1028}
1029#endif
1030
1031static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
1032			struct file *file, unsigned int cmd, unsigned long arg)
1033{
1034	int unit, err = -EFAULT;
1035	struct ppp *ppp;
1036	struct channel *chan;
1037	struct ppp_net *pn;
1038	int __user *p = (int __user *)arg;
1039
1040	switch (cmd) {
1041	case PPPIOCNEWUNIT:
1042		/* Create a new ppp unit */
1043		if (get_user(unit, p))
1044			break;
1045		err = ppp_create_interface(net, file, &unit);
1046		if (err < 0)
1047			break;
1048
1049		err = -EFAULT;
1050		if (put_user(unit, p))
1051			break;
1052		err = 0;
1053		break;
1054
1055	case PPPIOCATTACH:
1056		/* Attach to an existing ppp unit */
1057		if (get_user(unit, p))
1058			break;
1059		err = -ENXIO;
1060		pn = ppp_pernet(net);
1061		mutex_lock(&pn->all_ppp_mutex);
1062		ppp = ppp_find_unit(pn, unit);
1063		if (ppp) {
1064			refcount_inc(&ppp->file.refcnt);
1065			file->private_data = &ppp->file;
1066			err = 0;
1067		}
1068		mutex_unlock(&pn->all_ppp_mutex);
1069		break;
1070
1071	case PPPIOCATTCHAN:
1072		if (get_user(unit, p))
1073			break;
1074		err = -ENXIO;
1075		pn = ppp_pernet(net);
1076		spin_lock_bh(&pn->all_channels_lock);
1077		chan = ppp_find_channel(pn, unit);
1078		if (chan) {
1079			refcount_inc(&chan->file.refcnt);
1080			file->private_data = &chan->file;
1081			err = 0;
1082		}
1083		spin_unlock_bh(&pn->all_channels_lock);
1084		break;
1085
1086	default:
1087		err = -ENOTTY;
1088	}
1089
1090	return err;
1091}
1092
1093static const struct file_operations ppp_device_fops = {
1094	.owner		= THIS_MODULE,
1095	.read		= ppp_read,
1096	.write		= ppp_write,
1097	.poll		= ppp_poll,
1098	.unlocked_ioctl	= ppp_ioctl,
1099#ifdef CONFIG_COMPAT
1100	.compat_ioctl	= ppp_compat_ioctl,
1101#endif
1102	.open		= ppp_open,
1103	.release	= ppp_release,
1104	.llseek		= noop_llseek,
1105};
1106
1107static __net_init int ppp_init_net(struct net *net)
1108{
1109	struct ppp_net *pn = net_generic(net, ppp_net_id);
1110
1111	idr_init(&pn->units_idr);
1112	mutex_init(&pn->all_ppp_mutex);
1113
1114	INIT_LIST_HEAD(&pn->all_channels);
1115	INIT_LIST_HEAD(&pn->new_channels);
1116
1117	spin_lock_init(&pn->all_channels_lock);
1118
1119	return 0;
1120}
1121
1122static __net_exit void ppp_exit_net(struct net *net)
1123{
1124	struct ppp_net *pn = net_generic(net, ppp_net_id);
1125	struct net_device *dev;
1126	struct net_device *aux;
1127	struct ppp *ppp;
1128	LIST_HEAD(list);
1129	int id;
1130
1131	rtnl_lock();
1132	for_each_netdev_safe(net, dev, aux) {
1133		if (dev->netdev_ops == &ppp_netdev_ops)
1134			unregister_netdevice_queue(dev, &list);
1135	}
1136
1137	idr_for_each_entry(&pn->units_idr, ppp, id)
1138		/* Skip devices already unregistered by previous loop */
1139		if (!net_eq(dev_net(ppp->dev), net))
1140			unregister_netdevice_queue(ppp->dev, &list);
1141
1142	unregister_netdevice_many(&list);
1143	rtnl_unlock();
1144
1145	mutex_destroy(&pn->all_ppp_mutex);
1146	idr_destroy(&pn->units_idr);
1147	WARN_ON_ONCE(!list_empty(&pn->all_channels));
1148	WARN_ON_ONCE(!list_empty(&pn->new_channels));
1149}
1150
1151static struct pernet_operations ppp_net_ops = {
1152	.init = ppp_init_net,
1153	.exit = ppp_exit_net,
1154	.id   = &ppp_net_id,
1155	.size = sizeof(struct ppp_net),
1156};
1157
1158static int ppp_unit_register(struct ppp *ppp, int unit, bool ifname_is_set)
1159{
1160	struct ppp_net *pn = ppp_pernet(ppp->ppp_net);
1161	int ret;
1162
1163	mutex_lock(&pn->all_ppp_mutex);
1164
1165	if (unit < 0) {
1166		ret = unit_get(&pn->units_idr, ppp, 0);
1167		if (ret < 0)
1168			goto err;
1169		if (!ifname_is_set) {
1170			while (1) {
1171				snprintf(ppp->dev->name, IFNAMSIZ, "ppp%i", ret);
1172				if (!netdev_name_in_use(ppp->ppp_net, ppp->dev->name))
1173					break;
1174				unit_put(&pn->units_idr, ret);
1175				ret = unit_get(&pn->units_idr, ppp, ret + 1);
1176				if (ret < 0)
1177					goto err;
1178			}
1179		}
1180	} else {
1181		/* Caller asked for a specific unit number. Fail with -EEXIST
1182		 * if unavailable. For backward compatibility, return -EEXIST
1183		 * too if idr allocation fails; this makes pppd retry without
1184		 * requesting a specific unit number.
1185		 */
1186		if (unit_find(&pn->units_idr, unit)) {
1187			ret = -EEXIST;
1188			goto err;
1189		}
1190		ret = unit_set(&pn->units_idr, ppp, unit);
1191		if (ret < 0) {
1192			/* Rewrite error for backward compatibility */
1193			ret = -EEXIST;
1194			goto err;
1195		}
1196	}
1197	ppp->file.index = ret;
1198
1199	if (!ifname_is_set)
1200		snprintf(ppp->dev->name, IFNAMSIZ, "ppp%i", ppp->file.index);
1201
1202	mutex_unlock(&pn->all_ppp_mutex);
1203
1204	ret = register_netdevice(ppp->dev);
1205	if (ret < 0)
1206		goto err_unit;
1207
1208	atomic_inc(&ppp_unit_count);
1209
1210	return 0;
1211
1212err_unit:
1213	mutex_lock(&pn->all_ppp_mutex);
1214	unit_put(&pn->units_idr, ppp->file.index);
1215err:
1216	mutex_unlock(&pn->all_ppp_mutex);
1217
1218	return ret;
1219}
1220
1221static int ppp_dev_configure(struct net *src_net, struct net_device *dev,
1222			     const struct ppp_config *conf)
1223{
1224	struct ppp *ppp = netdev_priv(dev);
1225	int indx;
1226	int err;
1227	int cpu;
1228
1229	ppp->dev = dev;
1230	ppp->ppp_net = src_net;
1231	ppp->mru = PPP_MRU;
1232	ppp->owner = conf->file;
1233
1234	init_ppp_file(&ppp->file, INTERFACE);
1235	ppp->file.hdrlen = PPP_HDRLEN - 2; /* don't count proto bytes */
1236
1237	for (indx = 0; indx < NUM_NP; ++indx)
1238		ppp->npmode[indx] = NPMODE_PASS;
1239	INIT_LIST_HEAD(&ppp->channels);
1240	spin_lock_init(&ppp->rlock);
1241	spin_lock_init(&ppp->wlock);
1242
1243	ppp->xmit_recursion = alloc_percpu(int);
1244	if (!ppp->xmit_recursion) {
1245		err = -ENOMEM;
1246		goto err1;
1247	}
1248	for_each_possible_cpu(cpu)
1249		(*per_cpu_ptr(ppp->xmit_recursion, cpu)) = 0;
1250
1251#ifdef CONFIG_PPP_MULTILINK
1252	ppp->minseq = -1;
1253	skb_queue_head_init(&ppp->mrq);
1254#endif /* CONFIG_PPP_MULTILINK */
1255#ifdef CONFIG_PPP_FILTER
1256	ppp->pass_filter = NULL;
1257	ppp->active_filter = NULL;
1258#endif /* CONFIG_PPP_FILTER */
1259
1260	err = ppp_unit_register(ppp, conf->unit, conf->ifname_is_set);
1261	if (err < 0)
1262		goto err2;
1263
1264	conf->file->private_data = &ppp->file;
1265
1266	return 0;
1267err2:
1268	free_percpu(ppp->xmit_recursion);
1269err1:
1270	return err;
1271}
1272
1273static const struct nla_policy ppp_nl_policy[IFLA_PPP_MAX + 1] = {
1274	[IFLA_PPP_DEV_FD]	= { .type = NLA_S32 },
1275};
1276
1277static int ppp_nl_validate(struct nlattr *tb[], struct nlattr *data[],
1278			   struct netlink_ext_ack *extack)
1279{
1280	if (!data)
1281		return -EINVAL;
1282
1283	if (!data[IFLA_PPP_DEV_FD])
1284		return -EINVAL;
1285	if (nla_get_s32(data[IFLA_PPP_DEV_FD]) < 0)
1286		return -EBADF;
1287
1288	return 0;
1289}
1290
1291static int ppp_nl_newlink(struct net *src_net, struct net_device *dev,
1292			  struct nlattr *tb[], struct nlattr *data[],
1293			  struct netlink_ext_ack *extack)
1294{
1295	struct ppp_config conf = {
1296		.unit = -1,
1297		.ifname_is_set = true,
1298	};
1299	struct file *file;
1300	int err;
1301
1302	file = fget(nla_get_s32(data[IFLA_PPP_DEV_FD]));
1303	if (!file)
1304		return -EBADF;
1305
1306	/* rtnl_lock is already held here, but ppp_create_interface() locks
1307	 * ppp_mutex before holding rtnl_lock. Using mutex_trylock() avoids
1308	 * possible deadlock due to lock order inversion, at the cost of
1309	 * pushing the problem back to userspace.
1310	 */
1311	if (!mutex_trylock(&ppp_mutex)) {
1312		err = -EBUSY;
1313		goto out;
1314	}
1315
1316	if (file->f_op != &ppp_device_fops || file->private_data) {
1317		err = -EBADF;
1318		goto out_unlock;
1319	}
1320
1321	conf.file = file;
1322
1323	/* Don't use device name generated by the rtnetlink layer when ifname
1324	 * isn't specified. Let ppp_dev_configure() set the device name using
1325	 * the PPP unit identifer as suffix (i.e. ppp<unit_id>). This allows
1326	 * userspace to infer the device name using to the PPPIOCGUNIT ioctl.
1327	 */
1328	if (!tb[IFLA_IFNAME] || !nla_len(tb[IFLA_IFNAME]) || !*(char *)nla_data(tb[IFLA_IFNAME]))
1329		conf.ifname_is_set = false;
1330
1331	err = ppp_dev_configure(src_net, dev, &conf);
1332
1333out_unlock:
1334	mutex_unlock(&ppp_mutex);
1335out:
1336	fput(file);
1337
1338	return err;
1339}
1340
1341static void ppp_nl_dellink(struct net_device *dev, struct list_head *head)
1342{
1343	unregister_netdevice_queue(dev, head);
1344}
1345
1346static size_t ppp_nl_get_size(const struct net_device *dev)
1347{
1348	return 0;
1349}
1350
1351static int ppp_nl_fill_info(struct sk_buff *skb, const struct net_device *dev)
1352{
1353	return 0;
1354}
1355
1356static struct net *ppp_nl_get_link_net(const struct net_device *dev)
1357{
1358	struct ppp *ppp = netdev_priv(dev);
1359
1360	return ppp->ppp_net;
1361}
1362
1363static struct rtnl_link_ops ppp_link_ops __read_mostly = {
1364	.kind		= "ppp",
1365	.maxtype	= IFLA_PPP_MAX,
1366	.policy		= ppp_nl_policy,
1367	.priv_size	= sizeof(struct ppp),
1368	.setup		= ppp_setup,
1369	.validate	= ppp_nl_validate,
1370	.newlink	= ppp_nl_newlink,
1371	.dellink	= ppp_nl_dellink,
1372	.get_size	= ppp_nl_get_size,
1373	.fill_info	= ppp_nl_fill_info,
1374	.get_link_net	= ppp_nl_get_link_net,
1375};
1376
1377#define PPP_MAJOR	108
1378
1379/* Called at boot time if ppp is compiled into the kernel,
1380   or at module load time (from init_module) if compiled as a module. */
1381static int __init ppp_init(void)
1382{
1383	int err;
1384
1385	pr_info("PPP generic driver version " PPP_VERSION "\n");
1386
1387	err = register_pernet_device(&ppp_net_ops);
1388	if (err) {
1389		pr_err("failed to register PPP pernet device (%d)\n", err);
1390		goto out;
1391	}
1392
1393	err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
1394	if (err) {
1395		pr_err("failed to register PPP device (%d)\n", err);
1396		goto out_net;
1397	}
1398
1399	err = class_register(&ppp_class);
1400	if (err)
1401		goto out_chrdev;
1402
1403	err = rtnl_link_register(&ppp_link_ops);
1404	if (err) {
1405		pr_err("failed to register rtnetlink PPP handler\n");
1406		goto out_class;
1407	}
1408
1409	/* not a big deal if we fail here :-) */
1410	device_create(&ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
1411
1412	return 0;
1413
1414out_class:
1415	class_unregister(&ppp_class);
1416out_chrdev:
1417	unregister_chrdev(PPP_MAJOR, "ppp");
1418out_net:
1419	unregister_pernet_device(&ppp_net_ops);
1420out:
1421	return err;
1422}
1423
1424/*
1425 * Network interface unit routines.
1426 */
1427static netdev_tx_t
1428ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
1429{
1430	struct ppp *ppp = netdev_priv(dev);
1431	int npi, proto;
1432	unsigned char *pp;
1433
1434	npi = ethertype_to_npindex(ntohs(skb->protocol));
1435	if (npi < 0)
1436		goto outf;
1437
1438	/* Drop, accept or reject the packet */
1439	switch (ppp->npmode[npi]) {
1440	case NPMODE_PASS:
1441		break;
1442	case NPMODE_QUEUE:
1443		/* it would be nice to have a way to tell the network
1444		   system to queue this one up for later. */
1445		goto outf;
1446	case NPMODE_DROP:
1447	case NPMODE_ERROR:
1448		goto outf;
1449	}
1450
1451	/* Put the 2-byte PPP protocol number on the front,
1452	   making sure there is room for the address and control fields. */
1453	if (skb_cow_head(skb, PPP_HDRLEN))
1454		goto outf;
1455
1456	pp = skb_push(skb, 2);
1457	proto = npindex_to_proto[npi];
1458	put_unaligned_be16(proto, pp);
1459
1460	skb_scrub_packet(skb, !net_eq(ppp->ppp_net, dev_net(dev)));
1461	ppp_xmit_process(ppp, skb);
1462
1463	return NETDEV_TX_OK;
1464
1465 outf:
1466	kfree_skb(skb);
1467	++dev->stats.tx_dropped;
1468	return NETDEV_TX_OK;
1469}
1470
1471static int
1472ppp_net_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
1473		       void __user *addr, int cmd)
1474{
1475	struct ppp *ppp = netdev_priv(dev);
1476	int err = -EFAULT;
1477	struct ppp_stats stats;
1478	struct ppp_comp_stats cstats;
1479	char *vers;
1480
1481	switch (cmd) {
1482	case SIOCGPPPSTATS:
1483		ppp_get_stats(ppp, &stats);
1484		if (copy_to_user(addr, &stats, sizeof(stats)))
1485			break;
1486		err = 0;
1487		break;
1488
1489	case SIOCGPPPCSTATS:
1490		memset(&cstats, 0, sizeof(cstats));
1491		if (ppp->xc_state)
1492			ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
1493		if (ppp->rc_state)
1494			ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
1495		if (copy_to_user(addr, &cstats, sizeof(cstats)))
1496			break;
1497		err = 0;
1498		break;
1499
1500	case SIOCGPPPVER:
1501		vers = PPP_VERSION;
1502		if (copy_to_user(addr, vers, strlen(vers) + 1))
1503			break;
1504		err = 0;
1505		break;
1506
1507	default:
1508		err = -EINVAL;
1509	}
1510
1511	return err;
1512}
1513
1514static void
1515ppp_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats64)
1516{
1517	struct ppp *ppp = netdev_priv(dev);
1518
1519	ppp_recv_lock(ppp);
1520	stats64->rx_packets = ppp->stats64.rx_packets;
1521	stats64->rx_bytes   = ppp->stats64.rx_bytes;
1522	ppp_recv_unlock(ppp);
1523
1524	ppp_xmit_lock(ppp);
1525	stats64->tx_packets = ppp->stats64.tx_packets;
1526	stats64->tx_bytes   = ppp->stats64.tx_bytes;
1527	ppp_xmit_unlock(ppp);
1528
1529	stats64->rx_errors        = dev->stats.rx_errors;
1530	stats64->tx_errors        = dev->stats.tx_errors;
1531	stats64->rx_dropped       = dev->stats.rx_dropped;
1532	stats64->tx_dropped       = dev->stats.tx_dropped;
1533	stats64->rx_length_errors = dev->stats.rx_length_errors;
1534}
1535
1536static int ppp_dev_init(struct net_device *dev)
1537{
1538	struct ppp *ppp;
1539
1540	netdev_lockdep_set_classes(dev);
1541
1542	ppp = netdev_priv(dev);
1543	/* Let the netdevice take a reference on the ppp file. This ensures
1544	 * that ppp_destroy_interface() won't run before the device gets
1545	 * unregistered.
1546	 */
1547	refcount_inc(&ppp->file.refcnt);
1548
1549	return 0;
1550}
1551
1552static void ppp_dev_uninit(struct net_device *dev)
1553{
1554	struct ppp *ppp = netdev_priv(dev);
1555	struct ppp_net *pn = ppp_pernet(ppp->ppp_net);
1556
1557	ppp_lock(ppp);
1558	ppp->closing = 1;
1559	ppp_unlock(ppp);
1560
1561	mutex_lock(&pn->all_ppp_mutex);
1562	unit_put(&pn->units_idr, ppp->file.index);
1563	mutex_unlock(&pn->all_ppp_mutex);
1564
1565	ppp->owner = NULL;
1566
1567	ppp->file.dead = 1;
1568	wake_up_interruptible(&ppp->file.rwait);
1569}
1570
1571static void ppp_dev_priv_destructor(struct net_device *dev)
1572{
1573	struct ppp *ppp;
1574
1575	ppp = netdev_priv(dev);
1576	if (refcount_dec_and_test(&ppp->file.refcnt))
1577		ppp_destroy_interface(ppp);
1578}
1579
1580static int ppp_fill_forward_path(struct net_device_path_ctx *ctx,
1581				 struct net_device_path *path)
1582{
1583	struct ppp *ppp = netdev_priv(ctx->dev);
1584	struct ppp_channel *chan;
1585	struct channel *pch;
1586
1587	if (ppp->flags & SC_MULTILINK)
1588		return -EOPNOTSUPP;
1589
1590	if (list_empty(&ppp->channels))
1591		return -ENODEV;
1592
1593	pch = list_first_entry(&ppp->channels, struct channel, clist);
1594	chan = pch->chan;
1595	if (!chan->ops->fill_forward_path)
1596		return -EOPNOTSUPP;
1597
1598	return chan->ops->fill_forward_path(ctx, path, chan);
1599}
1600
1601static const struct net_device_ops ppp_netdev_ops = {
1602	.ndo_init	 = ppp_dev_init,
1603	.ndo_uninit      = ppp_dev_uninit,
1604	.ndo_start_xmit  = ppp_start_xmit,
1605	.ndo_siocdevprivate = ppp_net_siocdevprivate,
1606	.ndo_get_stats64 = ppp_get_stats64,
1607	.ndo_fill_forward_path = ppp_fill_forward_path,
1608};
1609
1610static const struct device_type ppp_type = {
1611	.name = "ppp",
1612};
1613
1614static void ppp_setup(struct net_device *dev)
1615{
1616	dev->netdev_ops = &ppp_netdev_ops;
1617	SET_NETDEV_DEVTYPE(dev, &ppp_type);
1618
1619	dev->features |= NETIF_F_LLTX;
1620
1621	dev->hard_header_len = PPP_HDRLEN;
1622	dev->mtu = PPP_MRU;
1623	dev->addr_len = 0;
1624	dev->tx_queue_len = 3;
1625	dev->type = ARPHRD_PPP;
1626	dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1627	dev->priv_destructor = ppp_dev_priv_destructor;
1628	netif_keep_dst(dev);
1629}
1630
1631/*
1632 * Transmit-side routines.
1633 */
1634
1635/* Called to do any work queued up on the transmit side that can now be done */
1636static void __ppp_xmit_process(struct ppp *ppp, struct sk_buff *skb)
1637{
1638	ppp_xmit_lock(ppp);
1639	if (!ppp->closing) {
1640		ppp_push(ppp);
1641
1642		if (skb)
1643			skb_queue_tail(&ppp->file.xq, skb);
1644		while (!ppp->xmit_pending &&
1645		       (skb = skb_dequeue(&ppp->file.xq)))
1646			ppp_send_frame(ppp, skb);
1647		/* If there's no work left to do, tell the core net
1648		   code that we can accept some more. */
1649		if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1650			netif_wake_queue(ppp->dev);
1651		else
1652			netif_stop_queue(ppp->dev);
1653	} else {
1654		kfree_skb(skb);
1655	}
1656	ppp_xmit_unlock(ppp);
1657}
1658
1659static void ppp_xmit_process(struct ppp *ppp, struct sk_buff *skb)
1660{
1661	local_bh_disable();
1662
1663	if (unlikely(*this_cpu_ptr(ppp->xmit_recursion)))
1664		goto err;
1665
1666	(*this_cpu_ptr(ppp->xmit_recursion))++;
1667	__ppp_xmit_process(ppp, skb);
1668	(*this_cpu_ptr(ppp->xmit_recursion))--;
1669
1670	local_bh_enable();
1671
1672	return;
1673
1674err:
1675	local_bh_enable();
1676
1677	kfree_skb(skb);
1678
1679	if (net_ratelimit())
1680		netdev_err(ppp->dev, "recursion detected\n");
1681}
1682
1683static inline struct sk_buff *
1684pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1685{
1686	struct sk_buff *new_skb;
1687	int len;
1688	int new_skb_size = ppp->dev->mtu +
1689		ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1690	int compressor_skb_size = ppp->dev->mtu +
1691		ppp->xcomp->comp_extra + PPP_HDRLEN;
1692	new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1693	if (!new_skb) {
1694		if (net_ratelimit())
1695			netdev_err(ppp->dev, "PPP: no memory (comp pkt)\n");
1696		return NULL;
1697	}
1698	if (ppp->dev->hard_header_len > PPP_HDRLEN)
1699		skb_reserve(new_skb,
1700			    ppp->dev->hard_header_len - PPP_HDRLEN);
1701
1702	/* compressor still expects A/C bytes in hdr */
1703	len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1704				   new_skb->data, skb->len + 2,
1705				   compressor_skb_size);
1706	if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1707		consume_skb(skb);
1708		skb = new_skb;
1709		skb_put(skb, len);
1710		skb_pull(skb, 2);	/* pull off A/C bytes */
1711	} else if (len == 0) {
1712		/* didn't compress, or CCP not up yet */
1713		consume_skb(new_skb);
1714		new_skb = skb;
1715	} else {
1716		/*
1717		 * (len < 0)
1718		 * MPPE requires that we do not send unencrypted
1719		 * frames.  The compressor will return -1 if we
1720		 * should drop the frame.  We cannot simply test
1721		 * the compress_proto because MPPE and MPPC share
1722		 * the same number.
1723		 */
1724		if (net_ratelimit())
1725			netdev_err(ppp->dev, "ppp: compressor dropped pkt\n");
1726		kfree_skb(skb);
1727		consume_skb(new_skb);
1728		new_skb = NULL;
1729	}
1730	return new_skb;
1731}
1732
1733/*
1734 * Compress and send a frame.
1735 * The caller should have locked the xmit path,
1736 * and xmit_pending should be 0.
1737 */
1738static void
1739ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1740{
1741	int proto = PPP_PROTO(skb);
1742	struct sk_buff *new_skb;
1743	int len;
1744	unsigned char *cp;
1745
1746	skb->dev = ppp->dev;
1747
1748	if (proto < 0x8000) {
1749#ifdef CONFIG_PPP_FILTER
1750		/* check if we should pass this packet */
1751		/* the filter instructions are constructed assuming
1752		   a four-byte PPP header on each packet */
1753		*(u8 *)skb_push(skb, 2) = 1;
1754		if (ppp->pass_filter &&
1755		    bpf_prog_run(ppp->pass_filter, skb) == 0) {
1756			if (ppp->debug & 1)
1757				netdev_printk(KERN_DEBUG, ppp->dev,
1758					      "PPP: outbound frame "
1759					      "not passed\n");
1760			kfree_skb(skb);
1761			return;
1762		}
1763		/* if this packet passes the active filter, record the time */
1764		if (!(ppp->active_filter &&
1765		      bpf_prog_run(ppp->active_filter, skb) == 0))
1766			ppp->last_xmit = jiffies;
1767		skb_pull(skb, 2);
1768#else
1769		/* for data packets, record the time */
1770		ppp->last_xmit = jiffies;
1771#endif /* CONFIG_PPP_FILTER */
1772	}
1773
1774	++ppp->stats64.tx_packets;
1775	ppp->stats64.tx_bytes += skb->len - PPP_PROTO_LEN;
1776
1777	switch (proto) {
1778	case PPP_IP:
1779		if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1780			break;
1781		/* try to do VJ TCP header compression */
1782		new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1783				    GFP_ATOMIC);
1784		if (!new_skb) {
1785			netdev_err(ppp->dev, "PPP: no memory (VJ comp pkt)\n");
1786			goto drop;
1787		}
1788		skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1789		cp = skb->data + 2;
1790		len = slhc_compress(ppp->vj, cp, skb->len - 2,
1791				    new_skb->data + 2, &cp,
1792				    !(ppp->flags & SC_NO_TCP_CCID));
1793		if (cp == skb->data + 2) {
1794			/* didn't compress */
1795			consume_skb(new_skb);
1796		} else {
1797			if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1798				proto = PPP_VJC_COMP;
1799				cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1800			} else {
1801				proto = PPP_VJC_UNCOMP;
1802				cp[0] = skb->data[2];
1803			}
1804			consume_skb(skb);
1805			skb = new_skb;
1806			cp = skb_put(skb, len + 2);
1807			cp[0] = 0;
1808			cp[1] = proto;
1809		}
1810		break;
1811
1812	case PPP_CCP:
1813		/* peek at outbound CCP frames */
1814		ppp_ccp_peek(ppp, skb, 0);
1815		break;
1816	}
1817
1818	/* try to do packet compression */
1819	if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state &&
1820	    proto != PPP_LCP && proto != PPP_CCP) {
1821		if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1822			if (net_ratelimit())
1823				netdev_err(ppp->dev,
1824					   "ppp: compression required but "
1825					   "down - pkt dropped.\n");
1826			goto drop;
1827		}
1828		skb = pad_compress_skb(ppp, skb);
1829		if (!skb)
1830			goto drop;
1831	}
1832
1833	/*
1834	 * If we are waiting for traffic (demand dialling),
1835	 * queue it up for pppd to receive.
1836	 */
1837	if (ppp->flags & SC_LOOP_TRAFFIC) {
1838		if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1839			goto drop;
1840		skb_queue_tail(&ppp->file.rq, skb);
1841		wake_up_interruptible(&ppp->file.rwait);
1842		return;
1843	}
1844
1845	ppp->xmit_pending = skb;
1846	ppp_push(ppp);
1847	return;
1848
1849 drop:
1850	kfree_skb(skb);
1851	++ppp->dev->stats.tx_errors;
1852}
1853
1854/*
1855 * Try to send the frame in xmit_pending.
1856 * The caller should have the xmit path locked.
1857 */
1858static void
1859ppp_push(struct ppp *ppp)
1860{
1861	struct list_head *list;
1862	struct channel *pch;
1863	struct sk_buff *skb = ppp->xmit_pending;
1864
1865	if (!skb)
1866		return;
1867
1868	list = &ppp->channels;
1869	if (list_empty(list)) {
1870		/* nowhere to send the packet, just drop it */
1871		ppp->xmit_pending = NULL;
1872		kfree_skb(skb);
1873		return;
1874	}
1875
1876	if ((ppp->flags & SC_MULTILINK) == 0) {
1877		/* not doing multilink: send it down the first channel */
1878		list = list->next;
1879		pch = list_entry(list, struct channel, clist);
1880
1881		spin_lock(&pch->downl);
1882		if (pch->chan) {
1883			if (pch->chan->ops->start_xmit(pch->chan, skb))
1884				ppp->xmit_pending = NULL;
1885		} else {
1886			/* channel got unregistered */
1887			kfree_skb(skb);
1888			ppp->xmit_pending = NULL;
1889		}
1890		spin_unlock(&pch->downl);
1891		return;
1892	}
1893
1894#ifdef CONFIG_PPP_MULTILINK
1895	/* Multilink: fragment the packet over as many links
1896	   as can take the packet at the moment. */
1897	if (!ppp_mp_explode(ppp, skb))
1898		return;
1899#endif /* CONFIG_PPP_MULTILINK */
1900
1901	ppp->xmit_pending = NULL;
1902	kfree_skb(skb);
1903}
1904
1905#ifdef CONFIG_PPP_MULTILINK
1906static bool mp_protocol_compress __read_mostly = true;
1907module_param(mp_protocol_compress, bool, 0644);
1908MODULE_PARM_DESC(mp_protocol_compress,
1909		 "compress protocol id in multilink fragments");
1910
1911/*
1912 * Divide a packet to be transmitted into fragments and
1913 * send them out the individual links.
1914 */
1915static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1916{
1917	int len, totlen;
1918	int i, bits, hdrlen, mtu;
1919	int flen;
1920	int navail, nfree, nzero;
1921	int nbigger;
1922	int totspeed;
1923	int totfree;
1924	unsigned char *p, *q;
1925	struct list_head *list;
1926	struct channel *pch;
1927	struct sk_buff *frag;
1928	struct ppp_channel *chan;
1929
1930	totspeed = 0; /*total bitrate of the bundle*/
1931	nfree = 0; /* # channels which have no packet already queued */
1932	navail = 0; /* total # of usable channels (not deregistered) */
1933	nzero = 0; /* number of channels with zero speed associated*/
1934	totfree = 0; /*total # of channels available and
1935				  *having no queued packets before
1936				  *starting the fragmentation*/
1937
1938	hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1939	i = 0;
1940	list_for_each_entry(pch, &ppp->channels, clist) {
1941		if (pch->chan) {
1942			pch->avail = 1;
1943			navail++;
1944			pch->speed = pch->chan->speed;
1945		} else {
1946			pch->avail = 0;
1947		}
1948		if (pch->avail) {
1949			if (skb_queue_empty(&pch->file.xq) ||
1950				!pch->had_frag) {
1951					if (pch->speed == 0)
1952						nzero++;
1953					else
1954						totspeed += pch->speed;
1955
1956					pch->avail = 2;
1957					++nfree;
1958					++totfree;
1959				}
1960			if (!pch->had_frag && i < ppp->nxchan)
1961				ppp->nxchan = i;
1962		}
1963		++i;
1964	}
1965	/*
1966	 * Don't start sending this packet unless at least half of
1967	 * the channels are free.  This gives much better TCP
1968	 * performance if we have a lot of channels.
1969	 */
1970	if (nfree == 0 || nfree < navail / 2)
1971		return 0; /* can't take now, leave it in xmit_pending */
1972
1973	/* Do protocol field compression */
1974	p = skb->data;
1975	len = skb->len;
1976	if (*p == 0 && mp_protocol_compress) {
1977		++p;
1978		--len;
1979	}
1980
1981	totlen = len;
1982	nbigger = len % nfree;
1983
1984	/* skip to the channel after the one we last used
1985	   and start at that one */
1986	list = &ppp->channels;
1987	for (i = 0; i < ppp->nxchan; ++i) {
1988		list = list->next;
1989		if (list == &ppp->channels) {
1990			i = 0;
1991			break;
1992		}
1993	}
1994
1995	/* create a fragment for each channel */
1996	bits = B;
1997	while (len > 0) {
1998		list = list->next;
1999		if (list == &ppp->channels) {
2000			i = 0;
2001			continue;
2002		}
2003		pch = list_entry(list, struct channel, clist);
2004		++i;
2005		if (!pch->avail)
2006			continue;
2007
2008		/*
2009		 * Skip this channel if it has a fragment pending already and
2010		 * we haven't given a fragment to all of the free channels.
2011		 */
2012		if (pch->avail == 1) {
2013			if (nfree > 0)
2014				continue;
2015		} else {
2016			pch->avail = 1;
2017		}
2018
2019		/* check the channel's mtu and whether it is still attached. */
2020		spin_lock(&pch->downl);
2021		if (pch->chan == NULL) {
2022			/* can't use this channel, it's being deregistered */
2023			if (pch->speed == 0)
2024				nzero--;
2025			else
2026				totspeed -= pch->speed;
2027
2028			spin_unlock(&pch->downl);
2029			pch->avail = 0;
2030			totlen = len;
2031			totfree--;
2032			nfree--;
2033			if (--navail == 0)
2034				break;
2035			continue;
2036		}
2037
2038		/*
2039		*if the channel speed is not set divide
2040		*the packet evenly among the free channels;
2041		*otherwise divide it according to the speed
2042		*of the channel we are going to transmit on
2043		*/
2044		flen = len;
2045		if (nfree > 0) {
2046			if (pch->speed == 0) {
2047				flen = len/nfree;
2048				if (nbigger > 0) {
2049					flen++;
2050					nbigger--;
2051				}
2052			} else {
2053				flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
2054					((totspeed*totfree)/pch->speed)) - hdrlen;
2055				if (nbigger > 0) {
2056					flen += ((totfree - nzero)*pch->speed)/totspeed;
2057					nbigger -= ((totfree - nzero)*pch->speed)/
2058							totspeed;
2059				}
2060			}
2061			nfree--;
2062		}
2063
2064		/*
2065		 *check if we are on the last channel or
2066		 *we exceded the length of the data to
2067		 *fragment
2068		 */
2069		if ((nfree <= 0) || (flen > len))
2070			flen = len;
2071		/*
2072		 *it is not worth to tx on slow channels:
2073		 *in that case from the resulting flen according to the
2074		 *above formula will be equal or less than zero.
2075		 *Skip the channel in this case
2076		 */
2077		if (flen <= 0) {
2078			pch->avail = 2;
2079			spin_unlock(&pch->downl);
2080			continue;
2081		}
2082
2083		/*
2084		 * hdrlen includes the 2-byte PPP protocol field, but the
2085		 * MTU counts only the payload excluding the protocol field.
2086		 * (RFC1661 Section 2)
2087		 */
2088		mtu = pch->chan->mtu - (hdrlen - 2);
2089		if (mtu < 4)
2090			mtu = 4;
2091		if (flen > mtu)
2092			flen = mtu;
2093		if (flen == len)
2094			bits |= E;
2095		frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
2096		if (!frag)
2097			goto noskb;
2098		q = skb_put(frag, flen + hdrlen);
2099
2100		/* make the MP header */
2101		put_unaligned_be16(PPP_MP, q);
2102		if (ppp->flags & SC_MP_XSHORTSEQ) {
2103			q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
2104			q[3] = ppp->nxseq;
2105		} else {
2106			q[2] = bits;
2107			q[3] = ppp->nxseq >> 16;
2108			q[4] = ppp->nxseq >> 8;
2109			q[5] = ppp->nxseq;
2110		}
2111
2112		memcpy(q + hdrlen, p, flen);
2113
2114		/* try to send it down the channel */
2115		chan = pch->chan;
2116		if (!skb_queue_empty(&pch->file.xq) ||
2117			!chan->ops->start_xmit(chan, frag))
2118			skb_queue_tail(&pch->file.xq, frag);
2119		pch->had_frag = 1;
2120		p += flen;
2121		len -= flen;
2122		++ppp->nxseq;
2123		bits = 0;
2124		spin_unlock(&pch->downl);
2125	}
2126	ppp->nxchan = i;
2127
2128	return 1;
2129
2130 noskb:
2131	spin_unlock(&pch->downl);
2132	if (ppp->debug & 1)
2133		netdev_err(ppp->dev, "PPP: no memory (fragment)\n");
2134	++ppp->dev->stats.tx_errors;
2135	++ppp->nxseq;
2136	return 1;	/* abandon the frame */
2137}
2138#endif /* CONFIG_PPP_MULTILINK */
2139
2140/* Try to send data out on a channel */
2141static void __ppp_channel_push(struct channel *pch)
2142{
2143	struct sk_buff *skb;
2144	struct ppp *ppp;
2145
2146	spin_lock(&pch->downl);
2147	if (pch->chan) {
2148		while (!skb_queue_empty(&pch->file.xq)) {
2149			skb = skb_dequeue(&pch->file.xq);
2150			if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
2151				/* put the packet back and try again later */
2152				skb_queue_head(&pch->file.xq, skb);
2153				break;
2154			}
2155		}
2156	} else {
2157		/* channel got deregistered */
2158		skb_queue_purge(&pch->file.xq);
2159	}
2160	spin_unlock(&pch->downl);
2161	/* see if there is anything from the attached unit to be sent */
2162	if (skb_queue_empty(&pch->file.xq)) {
2163		ppp = pch->ppp;
2164		if (ppp)
2165			__ppp_xmit_process(ppp, NULL);
2166	}
2167}
2168
2169static void ppp_channel_push(struct channel *pch)
2170{
2171	read_lock_bh(&pch->upl);
2172	if (pch->ppp) {
2173		(*this_cpu_ptr(pch->ppp->xmit_recursion))++;
2174		__ppp_channel_push(pch);
2175		(*this_cpu_ptr(pch->ppp->xmit_recursion))--;
2176	} else {
2177		__ppp_channel_push(pch);
2178	}
2179	read_unlock_bh(&pch->upl);
2180}
2181
2182/*
2183 * Receive-side routines.
2184 */
2185
2186struct ppp_mp_skb_parm {
2187	u32		sequence;
2188	u8		BEbits;
2189};
2190#define PPP_MP_CB(skb)	((struct ppp_mp_skb_parm *)((skb)->cb))
2191
2192static inline void
2193ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
2194{
2195	ppp_recv_lock(ppp);
2196	if (!ppp->closing)
2197		ppp_receive_frame(ppp, skb, pch);
2198	else
2199		kfree_skb(skb);
2200	ppp_recv_unlock(ppp);
2201}
2202
2203/**
2204 * __ppp_decompress_proto - Decompress protocol field, slim version.
2205 * @skb: Socket buffer where protocol field should be decompressed. It must have
2206 *	 at least 1 byte of head room and 1 byte of linear data. First byte of
2207 *	 data must be a protocol field byte.
2208 *
2209 * Decompress protocol field in PPP header if it's compressed, e.g. when
2210 * Protocol-Field-Compression (PFC) was negotiated. No checks w.r.t. skb data
2211 * length are done in this function.
2212 */
2213static void __ppp_decompress_proto(struct sk_buff *skb)
2214{
2215	if (skb->data[0] & 0x01)
2216		*(u8 *)skb_push(skb, 1) = 0x00;
2217}
2218
2219/**
2220 * ppp_decompress_proto - Check skb data room and decompress protocol field.
2221 * @skb: Socket buffer where protocol field should be decompressed. First byte
2222 *	 of data must be a protocol field byte.
2223 *
2224 * Decompress protocol field in PPP header if it's compressed, e.g. when
2225 * Protocol-Field-Compression (PFC) was negotiated. This function also makes
2226 * sure that skb data room is sufficient for Protocol field, before and after
2227 * decompression.
2228 *
2229 * Return: true - decompressed successfully, false - not enough room in skb.
2230 */
2231static bool ppp_decompress_proto(struct sk_buff *skb)
2232{
2233	/* At least one byte should be present (if protocol is compressed) */
2234	if (!pskb_may_pull(skb, 1))
2235		return false;
2236
2237	__ppp_decompress_proto(skb);
2238
2239	/* Protocol field should occupy 2 bytes when not compressed */
2240	return pskb_may_pull(skb, 2);
2241}
2242
2243/* Attempt to handle a frame via. a bridged channel, if one exists.
2244 * If the channel is bridged, the frame is consumed by the bridge.
2245 * If not, the caller must handle the frame by normal recv mechanisms.
2246 * Returns true if the frame is consumed, false otherwise.
2247 */
2248static bool ppp_channel_bridge_input(struct channel *pch, struct sk_buff *skb)
2249{
2250	struct channel *pchb;
2251
2252	rcu_read_lock();
2253	pchb = rcu_dereference(pch->bridge);
2254	if (!pchb)
2255		goto out_rcu;
2256
2257	spin_lock(&pchb->downl);
2258	if (!pchb->chan) {
2259		/* channel got unregistered */
2260		kfree_skb(skb);
2261		goto outl;
2262	}
2263
2264	skb_scrub_packet(skb, !net_eq(pch->chan_net, pchb->chan_net));
2265	if (!pchb->chan->ops->start_xmit(pchb->chan, skb))
2266		kfree_skb(skb);
2267
2268outl:
2269	spin_unlock(&pchb->downl);
2270out_rcu:
2271	rcu_read_unlock();
2272
2273	/* If pchb is set then we've consumed the packet */
2274	return !!pchb;
2275}
2276
2277void
2278ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
2279{
2280	struct channel *pch = chan->ppp;
2281	int proto;
2282
2283	if (!pch) {
2284		kfree_skb(skb);
2285		return;
2286	}
2287
2288	/* If the channel is bridged, transmit via. bridge */
2289	if (ppp_channel_bridge_input(pch, skb))
2290		return;
2291
2292	read_lock_bh(&pch->upl);
2293	if (!ppp_decompress_proto(skb)) {
2294		kfree_skb(skb);
2295		if (pch->ppp) {
2296			++pch->ppp->dev->stats.rx_length_errors;
2297			ppp_receive_error(pch->ppp);
2298		}
2299		goto done;
2300	}
2301
2302	proto = PPP_PROTO(skb);
2303	if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
2304		/* put it on the channel queue */
2305		skb_queue_tail(&pch->file.rq, skb);
2306		/* drop old frames if queue too long */
2307		while (pch->file.rq.qlen > PPP_MAX_RQLEN &&
2308		       (skb = skb_dequeue(&pch->file.rq)))
2309			kfree_skb(skb);
2310		wake_up_interruptible(&pch->file.rwait);
2311	} else {
2312		ppp_do_recv(pch->ppp, skb, pch);
2313	}
2314
2315done:
2316	read_unlock_bh(&pch->upl);
2317}
2318
2319/* Put a 0-length skb in the receive queue as an error indication */
2320void
2321ppp_input_error(struct ppp_channel *chan, int code)
2322{
2323	struct channel *pch = chan->ppp;
2324	struct sk_buff *skb;
2325
2326	if (!pch)
2327		return;
2328
2329	read_lock_bh(&pch->upl);
2330	if (pch->ppp) {
2331		skb = alloc_skb(0, GFP_ATOMIC);
2332		if (skb) {
2333			skb->len = 0;		/* probably unnecessary */
2334			skb->cb[0] = code;
2335			ppp_do_recv(pch->ppp, skb, pch);
2336		}
2337	}
2338	read_unlock_bh(&pch->upl);
2339}
2340
2341/*
2342 * We come in here to process a received frame.
2343 * The receive side of the ppp unit is locked.
2344 */
2345static void
2346ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
2347{
2348	/* note: a 0-length skb is used as an error indication */
2349	if (skb->len > 0) {
2350		skb_checksum_complete_unset(skb);
2351#ifdef CONFIG_PPP_MULTILINK
2352		/* XXX do channel-level decompression here */
2353		if (PPP_PROTO(skb) == PPP_MP)
2354			ppp_receive_mp_frame(ppp, skb, pch);
2355		else
2356#endif /* CONFIG_PPP_MULTILINK */
2357			ppp_receive_nonmp_frame(ppp, skb);
2358	} else {
2359		kfree_skb(skb);
2360		ppp_receive_error(ppp);
2361	}
2362}
2363
2364static void
2365ppp_receive_error(struct ppp *ppp)
2366{
2367	++ppp->dev->stats.rx_errors;
2368	if (ppp->vj)
2369		slhc_toss(ppp->vj);
2370}
2371
2372static void
2373ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
2374{
2375	struct sk_buff *ns;
2376	int proto, len, npi;
2377
2378	/*
2379	 * Decompress the frame, if compressed.
2380	 * Note that some decompressors need to see uncompressed frames
2381	 * that come in as well as compressed frames.
2382	 */
2383	if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN) &&
2384	    (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
2385		skb = ppp_decompress_frame(ppp, skb);
2386
2387	if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
2388		goto err;
2389
2390	/* At this point the "Protocol" field MUST be decompressed, either in
2391	 * ppp_input(), ppp_decompress_frame() or in ppp_receive_mp_frame().
2392	 */
2393	proto = PPP_PROTO(skb);
2394	switch (proto) {
2395	case PPP_VJC_COMP:
2396		/* decompress VJ compressed packets */
2397		if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
2398			goto err;
2399
2400		if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
2401			/* copy to a new sk_buff with more tailroom */
2402			ns = dev_alloc_skb(skb->len + 128);
2403			if (!ns) {
2404				netdev_err(ppp->dev, "PPP: no memory "
2405					   "(VJ decomp)\n");
2406				goto err;
2407			}
2408			skb_reserve(ns, 2);
2409			skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
2410			consume_skb(skb);
2411			skb = ns;
2412		}
2413		else
2414			skb->ip_summed = CHECKSUM_NONE;
2415
2416		len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
2417		if (len <= 0) {
2418			netdev_printk(KERN_DEBUG, ppp->dev,
2419				      "PPP: VJ decompression error\n");
2420			goto err;
2421		}
2422		len += 2;
2423		if (len > skb->len)
2424			skb_put(skb, len - skb->len);
2425		else if (len < skb->len)
2426			skb_trim(skb, len);
2427		proto = PPP_IP;
2428		break;
2429
2430	case PPP_VJC_UNCOMP:
2431		if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
2432			goto err;
2433
2434		/* Until we fix the decompressor need to make sure
2435		 * data portion is linear.
2436		 */
2437		if (!pskb_may_pull(skb, skb->len))
2438			goto err;
2439
2440		if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
2441			netdev_err(ppp->dev, "PPP: VJ uncompressed error\n");
2442			goto err;
2443		}
2444		proto = PPP_IP;
2445		break;
2446
2447	case PPP_CCP:
2448		ppp_ccp_peek(ppp, skb, 1);
2449		break;
2450	}
2451
2452	++ppp->stats64.rx_packets;
2453	ppp->stats64.rx_bytes += skb->len - 2;
2454
2455	npi = proto_to_npindex(proto);
2456	if (npi < 0) {
2457		/* control or unknown frame - pass it to pppd */
2458		skb_queue_tail(&ppp->file.rq, skb);
2459		/* limit queue length by dropping old frames */
2460		while (ppp->file.rq.qlen > PPP_MAX_RQLEN &&
2461		       (skb = skb_dequeue(&ppp->file.rq)))
2462			kfree_skb(skb);
2463		/* wake up any process polling or blocking on read */
2464		wake_up_interruptible(&ppp->file.rwait);
2465
2466	} else {
2467		/* network protocol frame - give it to the kernel */
2468
2469#ifdef CONFIG_PPP_FILTER
2470		/* check if the packet passes the pass and active filters */
2471		/* the filter instructions are constructed assuming
2472		   a four-byte PPP header on each packet */
2473		if (ppp->pass_filter || ppp->active_filter) {
2474			if (skb_unclone(skb, GFP_ATOMIC))
2475				goto err;
2476
2477			*(u8 *)skb_push(skb, 2) = 0;
2478			if (ppp->pass_filter &&
2479			    bpf_prog_run(ppp->pass_filter, skb) == 0) {
2480				if (ppp->debug & 1)
2481					netdev_printk(KERN_DEBUG, ppp->dev,
2482						      "PPP: inbound frame "
2483						      "not passed\n");
2484				kfree_skb(skb);
2485				return;
2486			}
2487			if (!(ppp->active_filter &&
2488			      bpf_prog_run(ppp->active_filter, skb) == 0))
2489				ppp->last_recv = jiffies;
2490			__skb_pull(skb, 2);
2491		} else
2492#endif /* CONFIG_PPP_FILTER */
2493			ppp->last_recv = jiffies;
2494
2495		if ((ppp->dev->flags & IFF_UP) == 0 ||
2496		    ppp->npmode[npi] != NPMODE_PASS) {
2497			kfree_skb(skb);
2498		} else {
2499			/* chop off protocol */
2500			skb_pull_rcsum(skb, 2);
2501			skb->dev = ppp->dev;
2502			skb->protocol = htons(npindex_to_ethertype[npi]);
2503			skb_reset_mac_header(skb);
2504			skb_scrub_packet(skb, !net_eq(ppp->ppp_net,
2505						      dev_net(ppp->dev)));
2506			netif_rx(skb);
2507		}
2508	}
2509	return;
2510
2511 err:
2512	kfree_skb(skb);
2513	ppp_receive_error(ppp);
2514}
2515
2516static struct sk_buff *
2517ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
2518{
2519	int proto = PPP_PROTO(skb);
2520	struct sk_buff *ns;
2521	int len;
2522
2523	/* Until we fix all the decompressor's need to make sure
2524	 * data portion is linear.
2525	 */
2526	if (!pskb_may_pull(skb, skb->len))
2527		goto err;
2528
2529	if (proto == PPP_COMP) {
2530		int obuff_size;
2531
2532		switch(ppp->rcomp->compress_proto) {
2533		case CI_MPPE:
2534			obuff_size = ppp->mru + PPP_HDRLEN + 1;
2535			break;
2536		default:
2537			obuff_size = ppp->mru + PPP_HDRLEN;
2538			break;
2539		}
2540
2541		ns = dev_alloc_skb(obuff_size);
2542		if (!ns) {
2543			netdev_err(ppp->dev, "ppp_decompress_frame: "
2544				   "no memory\n");
2545			goto err;
2546		}
2547		/* the decompressor still expects the A/C bytes in the hdr */
2548		len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
2549				skb->len + 2, ns->data, obuff_size);
2550		if (len < 0) {
2551			/* Pass the compressed frame to pppd as an
2552			   error indication. */
2553			if (len == DECOMP_FATALERROR)
2554				ppp->rstate |= SC_DC_FERROR;
2555			kfree_skb(ns);
2556			goto err;
2557		}
2558
2559		consume_skb(skb);
2560		skb = ns;
2561		skb_put(skb, len);
2562		skb_pull(skb, 2);	/* pull off the A/C bytes */
2563
2564		/* Don't call __ppp_decompress_proto() here, but instead rely on
2565		 * corresponding algo (mppe/bsd/deflate) to decompress it.
2566		 */
2567	} else {
2568		/* Uncompressed frame - pass to decompressor so it
2569		   can update its dictionary if necessary. */
2570		if (ppp->rcomp->incomp)
2571			ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
2572					   skb->len + 2);
2573	}
2574
2575	return skb;
2576
2577 err:
2578	ppp->rstate |= SC_DC_ERROR;
2579	ppp_receive_error(ppp);
2580	return skb;
2581}
2582
2583#ifdef CONFIG_PPP_MULTILINK
2584/*
2585 * Receive a multilink frame.
2586 * We put it on the reconstruction queue and then pull off
2587 * as many completed frames as we can.
2588 */
2589static void
2590ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
2591{
2592	u32 mask, seq;
2593	struct channel *ch;
2594	int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
2595
2596	if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
2597		goto err;		/* no good, throw it away */
2598
2599	/* Decode sequence number and begin/end bits */
2600	if (ppp->flags & SC_MP_SHORTSEQ) {
2601		seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
2602		mask = 0xfff;
2603	} else {
2604		seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
2605		mask = 0xffffff;
2606	}
2607	PPP_MP_CB(skb)->BEbits = skb->data[2];
2608	skb_pull(skb, mphdrlen);	/* pull off PPP and MP headers */
2609
2610	/*
2611	 * Do protocol ID decompression on the first fragment of each packet.
2612	 * We have to do that here, because ppp_receive_nonmp_frame() expects
2613	 * decompressed protocol field.
2614	 */
2615	if (PPP_MP_CB(skb)->BEbits & B)
2616		__ppp_decompress_proto(skb);
2617
2618	/*
2619	 * Expand sequence number to 32 bits, making it as close
2620	 * as possible to ppp->minseq.
2621	 */
2622	seq |= ppp->minseq & ~mask;
2623	if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
2624		seq += mask + 1;
2625	else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
2626		seq -= mask + 1;	/* should never happen */
2627	PPP_MP_CB(skb)->sequence = seq;
2628	pch->lastseq = seq;
2629
2630	/*
2631	 * If this packet comes before the next one we were expecting,
2632	 * drop it.
2633	 */
2634	if (seq_before(seq, ppp->nextseq)) {
2635		kfree_skb(skb);
2636		++ppp->dev->stats.rx_dropped;
2637		ppp_receive_error(ppp);
2638		return;
2639	}
2640
2641	/*
2642	 * Reevaluate minseq, the minimum over all channels of the
2643	 * last sequence number received on each channel.  Because of
2644	 * the increasing sequence number rule, we know that any fragment
2645	 * before `minseq' which hasn't arrived is never going to arrive.
2646	 * The list of channels can't change because we have the receive
2647	 * side of the ppp unit locked.
2648	 */
2649	list_for_each_entry(ch, &ppp->channels, clist) {
2650		if (seq_before(ch->lastseq, seq))
2651			seq = ch->lastseq;
2652	}
2653	if (seq_before(ppp->minseq, seq))
2654		ppp->minseq = seq;
2655
2656	/* Put the fragment on the reconstruction queue */
2657	ppp_mp_insert(ppp, skb);
2658
2659	/* If the queue is getting long, don't wait any longer for packets
2660	   before the start of the queue. */
2661	if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
2662		struct sk_buff *mskb = skb_peek(&ppp->mrq);
2663		if (seq_before(ppp->minseq, PPP_MP_CB(mskb)->sequence))
2664			ppp->minseq = PPP_MP_CB(mskb)->sequence;
2665	}
2666
2667	/* Pull completed packets off the queue and receive them. */
2668	while ((skb = ppp_mp_reconstruct(ppp))) {
2669		if (pskb_may_pull(skb, 2))
2670			ppp_receive_nonmp_frame(ppp, skb);
2671		else {
2672			++ppp->dev->stats.rx_length_errors;
2673			kfree_skb(skb);
2674			ppp_receive_error(ppp);
2675		}
2676	}
2677
2678	return;
2679
2680 err:
2681	kfree_skb(skb);
2682	ppp_receive_error(ppp);
2683}
2684
2685/*
2686 * Insert a fragment on the MP reconstruction queue.
2687 * The queue is ordered by increasing sequence number.
2688 */
2689static void
2690ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
2691{
2692	struct sk_buff *p;
2693	struct sk_buff_head *list = &ppp->mrq;
2694	u32 seq = PPP_MP_CB(skb)->sequence;
2695
2696	/* N.B. we don't need to lock the list lock because we have the
2697	   ppp unit receive-side lock. */
2698	skb_queue_walk(list, p) {
2699		if (seq_before(seq, PPP_MP_CB(p)->sequence))
2700			break;
2701	}
2702	__skb_queue_before(list, p, skb);
2703}
2704
2705/*
2706 * Reconstruct a packet from the MP fragment queue.
2707 * We go through increasing sequence numbers until we find a
2708 * complete packet, or we get to the sequence number for a fragment
2709 * which hasn't arrived but might still do so.
2710 */
2711static struct sk_buff *
2712ppp_mp_reconstruct(struct ppp *ppp)
2713{
2714	u32 seq = ppp->nextseq;
2715	u32 minseq = ppp->minseq;
2716	struct sk_buff_head *list = &ppp->mrq;
2717	struct sk_buff *p, *tmp;
2718	struct sk_buff *head, *tail;
2719	struct sk_buff *skb = NULL;
2720	int lost = 0, len = 0;
2721
2722	if (ppp->mrru == 0)	/* do nothing until mrru is set */
2723		return NULL;
2724	head = __skb_peek(list);
2725	tail = NULL;
2726	skb_queue_walk_safe(list, p, tmp) {
2727	again:
2728		if (seq_before(PPP_MP_CB(p)->sequence, seq)) {
2729			/* this can't happen, anyway ignore the skb */
2730			netdev_err(ppp->dev, "ppp_mp_reconstruct bad "
2731				   "seq %u < %u\n",
2732				   PPP_MP_CB(p)->sequence, seq);
2733			__skb_unlink(p, list);
2734			kfree_skb(p);
2735			continue;
2736		}
2737		if (PPP_MP_CB(p)->sequence != seq) {
2738			u32 oldseq;
2739			/* Fragment `seq' is missing.  If it is after
2740			   minseq, it might arrive later, so stop here. */
2741			if (seq_after(seq, minseq))
2742				break;
2743			/* Fragment `seq' is lost, keep going. */
2744			lost = 1;
2745			oldseq = seq;
2746			seq = seq_before(minseq, PPP_MP_CB(p)->sequence)?
2747				minseq + 1: PPP_MP_CB(p)->sequence;
2748
2749			if (ppp->debug & 1)
2750				netdev_printk(KERN_DEBUG, ppp->dev,
2751					      "lost frag %u..%u\n",
2752					      oldseq, seq-1);
2753
2754			goto again;
2755		}
2756
2757		/*
2758		 * At this point we know that all the fragments from
2759		 * ppp->nextseq to seq are either present or lost.
2760		 * Also, there are no complete packets in the queue
2761		 * that have no missing fragments and end before this
2762		 * fragment.
2763		 */
2764
2765		/* B bit set indicates this fragment starts a packet */
2766		if (PPP_MP_CB(p)->BEbits & B) {
2767			head = p;
2768			lost = 0;
2769			len = 0;
2770		}
2771
2772		len += p->len;
2773
2774		/* Got a complete packet yet? */
2775		if (lost == 0 && (PPP_MP_CB(p)->BEbits & E) &&
2776		    (PPP_MP_CB(head)->BEbits & B)) {
2777			if (len > ppp->mrru + 2) {
2778				++ppp->dev->stats.rx_length_errors;
2779				netdev_printk(KERN_DEBUG, ppp->dev,
2780					      "PPP: reconstructed packet"
2781					      " is too long (%d)\n", len);
2782			} else {
2783				tail = p;
2784				break;
2785			}
2786			ppp->nextseq = seq + 1;
2787		}
2788
2789		/*
2790		 * If this is the ending fragment of a packet,
2791		 * and we haven't found a complete valid packet yet,
2792		 * we can discard up to and including this fragment.
2793		 */
2794		if (PPP_MP_CB(p)->BEbits & E) {
2795			struct sk_buff *tmp2;
2796
2797			skb_queue_reverse_walk_from_safe(list, p, tmp2) {
2798				if (ppp->debug & 1)
2799					netdev_printk(KERN_DEBUG, ppp->dev,
2800						      "discarding frag %u\n",
2801						      PPP_MP_CB(p)->sequence);
2802				__skb_unlink(p, list);
2803				kfree_skb(p);
2804			}
2805			head = skb_peek(list);
2806			if (!head)
2807				break;
2808		}
2809		++seq;
2810	}
2811
2812	/* If we have a complete packet, copy it all into one skb. */
2813	if (tail != NULL) {
2814		/* If we have discarded any fragments,
2815		   signal a receive error. */
2816		if (PPP_MP_CB(head)->sequence != ppp->nextseq) {
2817			skb_queue_walk_safe(list, p, tmp) {
2818				if (p == head)
2819					break;
2820				if (ppp->debug & 1)
2821					netdev_printk(KERN_DEBUG, ppp->dev,
2822						      "discarding frag %u\n",
2823						      PPP_MP_CB(p)->sequence);
2824				__skb_unlink(p, list);
2825				kfree_skb(p);
2826			}
2827
2828			if (ppp->debug & 1)
2829				netdev_printk(KERN_DEBUG, ppp->dev,
2830					      "  missed pkts %u..%u\n",
2831					      ppp->nextseq,
2832					      PPP_MP_CB(head)->sequence-1);
2833			++ppp->dev->stats.rx_dropped;
2834			ppp_receive_error(ppp);
2835		}
2836
2837		skb = head;
2838		if (head != tail) {
2839			struct sk_buff **fragpp = &skb_shinfo(skb)->frag_list;
2840			p = skb_queue_next(list, head);
2841			__skb_unlink(skb, list);
2842			skb_queue_walk_from_safe(list, p, tmp) {
2843				__skb_unlink(p, list);
2844				*fragpp = p;
2845				p->next = NULL;
2846				fragpp = &p->next;
2847
2848				skb->len += p->len;
2849				skb->data_len += p->len;
2850				skb->truesize += p->truesize;
2851
2852				if (p == tail)
2853					break;
2854			}
2855		} else {
2856			__skb_unlink(skb, list);
2857		}
2858
2859		ppp->nextseq = PPP_MP_CB(tail)->sequence + 1;
2860	}
2861
2862	return skb;
2863}
2864#endif /* CONFIG_PPP_MULTILINK */
2865
2866/*
2867 * Channel interface.
2868 */
2869
2870/* Create a new, unattached ppp channel. */
2871int ppp_register_channel(struct ppp_channel *chan)
2872{
2873	return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2874}
2875
2876/* Create a new, unattached ppp channel for specified net. */
2877int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2878{
2879	struct channel *pch;
2880	struct ppp_net *pn;
2881
2882	pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2883	if (!pch)
2884		return -ENOMEM;
2885
2886	pn = ppp_pernet(net);
2887
2888	pch->ppp = NULL;
2889	pch->chan = chan;
2890	pch->chan_net = get_net_track(net, &pch->ns_tracker, GFP_KERNEL);
2891	chan->ppp = pch;
2892	init_ppp_file(&pch->file, CHANNEL);
2893	pch->file.hdrlen = chan->hdrlen;
2894#ifdef CONFIG_PPP_MULTILINK
2895	pch->lastseq = -1;
2896#endif /* CONFIG_PPP_MULTILINK */
2897	init_rwsem(&pch->chan_sem);
2898	spin_lock_init(&pch->downl);
2899	rwlock_init(&pch->upl);
2900
2901	spin_lock_bh(&pn->all_channels_lock);
2902	pch->file.index = ++pn->last_channel_index;
2903	list_add(&pch->list, &pn->new_channels);
2904	atomic_inc(&channel_count);
2905	spin_unlock_bh(&pn->all_channels_lock);
2906
2907	return 0;
2908}
2909
2910/*
2911 * Return the index of a channel.
2912 */
2913int ppp_channel_index(struct ppp_channel *chan)
2914{
2915	struct channel *pch = chan->ppp;
2916
2917	if (pch)
2918		return pch->file.index;
2919	return -1;
2920}
2921
2922/*
2923 * Return the PPP unit number to which a channel is connected.
2924 */
2925int ppp_unit_number(struct ppp_channel *chan)
2926{
2927	struct channel *pch = chan->ppp;
2928	int unit = -1;
2929
2930	if (pch) {
2931		read_lock_bh(&pch->upl);
2932		if (pch->ppp)
2933			unit = pch->ppp->file.index;
2934		read_unlock_bh(&pch->upl);
2935	}
2936	return unit;
2937}
2938
2939/*
2940 * Return the PPP device interface name of a channel.
2941 */
2942char *ppp_dev_name(struct ppp_channel *chan)
2943{
2944	struct channel *pch = chan->ppp;
2945	char *name = NULL;
2946
2947	if (pch) {
2948		read_lock_bh(&pch->upl);
2949		if (pch->ppp && pch->ppp->dev)
2950			name = pch->ppp->dev->name;
2951		read_unlock_bh(&pch->upl);
2952	}
2953	return name;
2954}
2955
2956
2957/*
2958 * Disconnect a channel from the generic layer.
2959 * This must be called in process context.
2960 */
2961void
2962ppp_unregister_channel(struct ppp_channel *chan)
2963{
2964	struct channel *pch = chan->ppp;
2965	struct ppp_net *pn;
2966
2967	if (!pch)
2968		return;		/* should never happen */
2969
2970	chan->ppp = NULL;
2971
2972	/*
2973	 * This ensures that we have returned from any calls into
2974	 * the channel's start_xmit or ioctl routine before we proceed.
2975	 */
2976	down_write(&pch->chan_sem);
2977	spin_lock_bh(&pch->downl);
2978	pch->chan = NULL;
2979	spin_unlock_bh(&pch->downl);
2980	up_write(&pch->chan_sem);
2981	ppp_disconnect_channel(pch);
2982
2983	pn = ppp_pernet(pch->chan_net);
2984	spin_lock_bh(&pn->all_channels_lock);
2985	list_del(&pch->list);
2986	spin_unlock_bh(&pn->all_channels_lock);
2987
2988	ppp_unbridge_channels(pch);
2989
2990	pch->file.dead = 1;
2991	wake_up_interruptible(&pch->file.rwait);
2992
2993	if (refcount_dec_and_test(&pch->file.refcnt))
2994		ppp_destroy_channel(pch);
2995}
2996
2997/*
2998 * Callback from a channel when it can accept more to transmit.
2999 * This should be called at BH/softirq level, not interrupt level.
3000 */
3001void
3002ppp_output_wakeup(struct ppp_channel *chan)
3003{
3004	struct channel *pch = chan->ppp;
3005
3006	if (!pch)
3007		return;
3008	ppp_channel_push(pch);
3009}
3010
3011/*
3012 * Compression control.
3013 */
3014
3015/* Process the PPPIOCSCOMPRESS ioctl. */
3016static int
3017ppp_set_compress(struct ppp *ppp, struct ppp_option_data *data)
3018{
3019	int err = -EFAULT;
3020	struct compressor *cp, *ocomp;
3021	void *state, *ostate;
3022	unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
3023
3024	if (data->length > CCP_MAX_OPTION_LENGTH)
3025		goto out;
3026	if (copy_from_user(ccp_option, data->ptr, data->length))
3027		goto out;
3028
3029	err = -EINVAL;
3030	if (data->length < 2 || ccp_option[1] < 2 || ccp_option[1] > data->length)
3031		goto out;
3032
3033	cp = try_then_request_module(
3034		find_compressor(ccp_option[0]),
3035		"ppp-compress-%d", ccp_option[0]);
3036	if (!cp)
3037		goto out;
3038
3039	err = -ENOBUFS;
3040	if (data->transmit) {
3041		state = cp->comp_alloc(ccp_option, data->length);
3042		if (state) {
3043			ppp_xmit_lock(ppp);
3044			ppp->xstate &= ~SC_COMP_RUN;
3045			ocomp = ppp->xcomp;
3046			ostate = ppp->xc_state;
3047			ppp->xcomp = cp;
3048			ppp->xc_state = state;
3049			ppp_xmit_unlock(ppp);
3050			if (ostate) {
3051				ocomp->comp_free(ostate);
3052				module_put(ocomp->owner);
3053			}
3054			err = 0;
3055		} else
3056			module_put(cp->owner);
3057
3058	} else {
3059		state = cp->decomp_alloc(ccp_option, data->length);
3060		if (state) {
3061			ppp_recv_lock(ppp);
3062			ppp->rstate &= ~SC_DECOMP_RUN;
3063			ocomp = ppp->rcomp;
3064			ostate = ppp->rc_state;
3065			ppp->rcomp = cp;
3066			ppp->rc_state = state;
3067			ppp_recv_unlock(ppp);
3068			if (ostate) {
3069				ocomp->decomp_free(ostate);
3070				module_put(ocomp->owner);
3071			}
3072			err = 0;
3073		} else
3074			module_put(cp->owner);
3075	}
3076
3077 out:
3078	return err;
3079}
3080
3081/*
3082 * Look at a CCP packet and update our state accordingly.
3083 * We assume the caller has the xmit or recv path locked.
3084 */
3085static void
3086ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
3087{
3088	unsigned char *dp;
3089	int len;
3090
3091	if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
3092		return;	/* no header */
3093	dp = skb->data + 2;
3094
3095	switch (CCP_CODE(dp)) {
3096	case CCP_CONFREQ:
3097
3098		/* A ConfReq starts negotiation of compression
3099		 * in one direction of transmission,
3100		 * and hence brings it down...but which way?
3101		 *
3102		 * Remember:
3103		 * A ConfReq indicates what the sender would like to receive
3104		 */
3105		if(inbound)
3106			/* He is proposing what I should send */
3107			ppp->xstate &= ~SC_COMP_RUN;
3108		else
3109			/* I am proposing to what he should send */
3110			ppp->rstate &= ~SC_DECOMP_RUN;
3111
3112		break;
3113
3114	case CCP_TERMREQ:
3115	case CCP_TERMACK:
3116		/*
3117		 * CCP is going down, both directions of transmission
3118		 */
3119		ppp->rstate &= ~SC_DECOMP_RUN;
3120		ppp->xstate &= ~SC_COMP_RUN;
3121		break;
3122
3123	case CCP_CONFACK:
3124		if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
3125			break;
3126		len = CCP_LENGTH(dp);
3127		if (!pskb_may_pull(skb, len + 2))
3128			return;		/* too short */
3129		dp += CCP_HDRLEN;
3130		len -= CCP_HDRLEN;
3131		if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
3132			break;
3133		if (inbound) {
3134			/* we will start receiving compressed packets */
3135			if (!ppp->rc_state)
3136				break;
3137			if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
3138					ppp->file.index, 0, ppp->mru, ppp->debug)) {
3139				ppp->rstate |= SC_DECOMP_RUN;
3140				ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
3141			}
3142		} else {
3143			/* we will soon start sending compressed packets */
3144			if (!ppp->xc_state)
3145				break;
3146			if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
3147					ppp->file.index, 0, ppp->debug))
3148				ppp->xstate |= SC_COMP_RUN;
3149		}
3150		break;
3151
3152	case CCP_RESETACK:
3153		/* reset the [de]compressor */
3154		if ((ppp->flags & SC_CCP_UP) == 0)
3155			break;
3156		if (inbound) {
3157			if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
3158				ppp->rcomp->decomp_reset(ppp->rc_state);
3159				ppp->rstate &= ~SC_DC_ERROR;
3160			}
3161		} else {
3162			if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
3163				ppp->xcomp->comp_reset(ppp->xc_state);
3164		}
3165		break;
3166	}
3167}
3168
3169/* Free up compression resources. */
3170static void
3171ppp_ccp_closed(struct ppp *ppp)
3172{
3173	void *xstate, *rstate;
3174	struct compressor *xcomp, *rcomp;
3175
3176	ppp_lock(ppp);
3177	ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
3178	ppp->xstate = 0;
3179	xcomp = ppp->xcomp;
3180	xstate = ppp->xc_state;
3181	ppp->xc_state = NULL;
3182	ppp->rstate = 0;
3183	rcomp = ppp->rcomp;
3184	rstate = ppp->rc_state;
3185	ppp->rc_state = NULL;
3186	ppp_unlock(ppp);
3187
3188	if (xstate) {
3189		xcomp->comp_free(xstate);
3190		module_put(xcomp->owner);
3191	}
3192	if (rstate) {
3193		rcomp->decomp_free(rstate);
3194		module_put(rcomp->owner);
3195	}
3196}
3197
3198/* List of compressors. */
3199static LIST_HEAD(compressor_list);
3200static DEFINE_SPINLOCK(compressor_list_lock);
3201
3202struct compressor_entry {
3203	struct list_head list;
3204	struct compressor *comp;
3205};
3206
3207static struct compressor_entry *
3208find_comp_entry(int proto)
3209{
3210	struct compressor_entry *ce;
3211
3212	list_for_each_entry(ce, &compressor_list, list) {
3213		if (ce->comp->compress_proto == proto)
3214			return ce;
3215	}
3216	return NULL;
3217}
3218
3219/* Register a compressor */
3220int
3221ppp_register_compressor(struct compressor *cp)
3222{
3223	struct compressor_entry *ce;
3224	int ret;
3225	spin_lock(&compressor_list_lock);
3226	ret = -EEXIST;
3227	if (find_comp_entry(cp->compress_proto))
3228		goto out;
3229	ret = -ENOMEM;
3230	ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
3231	if (!ce)
3232		goto out;
3233	ret = 0;
3234	ce->comp = cp;
3235	list_add(&ce->list, &compressor_list);
3236 out:
3237	spin_unlock(&compressor_list_lock);
3238	return ret;
3239}
3240
3241/* Unregister a compressor */
3242void
3243ppp_unregister_compressor(struct compressor *cp)
3244{
3245	struct compressor_entry *ce;
3246
3247	spin_lock(&compressor_list_lock);
3248	ce = find_comp_entry(cp->compress_proto);
3249	if (ce && ce->comp == cp) {
3250		list_del(&ce->list);
3251		kfree(ce);
3252	}
3253	spin_unlock(&compressor_list_lock);
3254}
3255
3256/* Find a compressor. */
3257static struct compressor *
3258find_compressor(int type)
3259{
3260	struct compressor_entry *ce;
3261	struct compressor *cp = NULL;
3262
3263	spin_lock(&compressor_list_lock);
3264	ce = find_comp_entry(type);
3265	if (ce) {
3266		cp = ce->comp;
3267		if (!try_module_get(cp->owner))
3268			cp = NULL;
3269	}
3270	spin_unlock(&compressor_list_lock);
3271	return cp;
3272}
3273
3274/*
3275 * Miscelleneous stuff.
3276 */
3277
3278static void
3279ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
3280{
3281	struct slcompress *vj = ppp->vj;
3282
3283	memset(st, 0, sizeof(*st));
3284	st->p.ppp_ipackets = ppp->stats64.rx_packets;
3285	st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
3286	st->p.ppp_ibytes = ppp->stats64.rx_bytes;
3287	st->p.ppp_opackets = ppp->stats64.tx_packets;
3288	st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
3289	st->p.ppp_obytes = ppp->stats64.tx_bytes;
3290	if (!vj)
3291		return;
3292	st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
3293	st->vj.vjs_compressed = vj->sls_o_compressed;
3294	st->vj.vjs_searches = vj->sls_o_searches;
3295	st->vj.vjs_misses = vj->sls_o_misses;
3296	st->vj.vjs_errorin = vj->sls_i_error;
3297	st->vj.vjs_tossed = vj->sls_i_tossed;
3298	st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
3299	st->vj.vjs_compressedin = vj->sls_i_compressed;
3300}
3301
3302/*
3303 * Stuff for handling the lists of ppp units and channels
3304 * and for initialization.
3305 */
3306
3307/*
3308 * Create a new ppp interface unit.  Fails if it can't allocate memory
3309 * or if there is already a unit with the requested number.
3310 * unit == -1 means allocate a new number.
3311 */
3312static int ppp_create_interface(struct net *net, struct file *file, int *unit)
3313{
3314	struct ppp_config conf = {
3315		.file = file,
3316		.unit = *unit,
3317		.ifname_is_set = false,
3318	};
3319	struct net_device *dev;
3320	struct ppp *ppp;
3321	int err;
3322
3323	dev = alloc_netdev(sizeof(struct ppp), "", NET_NAME_ENUM, ppp_setup);
3324	if (!dev) {
3325		err = -ENOMEM;
3326		goto err;
3327	}
3328	dev_net_set(dev, net);
3329	dev->rtnl_link_ops = &ppp_link_ops;
3330
3331	rtnl_lock();
3332
3333	err = ppp_dev_configure(net, dev, &conf);
3334	if (err < 0)
3335		goto err_dev;
3336	ppp = netdev_priv(dev);
3337	*unit = ppp->file.index;
3338
3339	rtnl_unlock();
3340
3341	return 0;
3342
3343err_dev:
3344	rtnl_unlock();
3345	free_netdev(dev);
3346err:
3347	return err;
3348}
3349
3350/*
3351 * Initialize a ppp_file structure.
3352 */
3353static void
3354init_ppp_file(struct ppp_file *pf, int kind)
3355{
3356	pf->kind = kind;
3357	skb_queue_head_init(&pf->xq);
3358	skb_queue_head_init(&pf->rq);
3359	refcount_set(&pf->refcnt, 1);
3360	init_waitqueue_head(&pf->rwait);
3361}
3362
3363/*
3364 * Free the memory used by a ppp unit.  This is only called once
3365 * there are no channels connected to the unit and no file structs
3366 * that reference the unit.
3367 */
3368static void ppp_destroy_interface(struct ppp *ppp)
3369{
3370	atomic_dec(&ppp_unit_count);
3371
3372	if (!ppp->file.dead || ppp->n_channels) {
3373		/* "can't happen" */
3374		netdev_err(ppp->dev, "ppp: destroying ppp struct %p "
3375			   "but dead=%d n_channels=%d !\n",
3376			   ppp, ppp->file.dead, ppp->n_channels);
3377		return;
3378	}
3379
3380	ppp_ccp_closed(ppp);
3381	if (ppp->vj) {
3382		slhc_free(ppp->vj);
3383		ppp->vj = NULL;
3384	}
3385	skb_queue_purge(&ppp->file.xq);
3386	skb_queue_purge(&ppp->file.rq);
3387#ifdef CONFIG_PPP_MULTILINK
3388	skb_queue_purge(&ppp->mrq);
3389#endif /* CONFIG_PPP_MULTILINK */
3390#ifdef CONFIG_PPP_FILTER
3391	if (ppp->pass_filter) {
3392		bpf_prog_destroy(ppp->pass_filter);
3393		ppp->pass_filter = NULL;
3394	}
3395
3396	if (ppp->active_filter) {
3397		bpf_prog_destroy(ppp->active_filter);
3398		ppp->active_filter = NULL;
3399	}
3400#endif /* CONFIG_PPP_FILTER */
3401
3402	kfree_skb(ppp->xmit_pending);
3403	free_percpu(ppp->xmit_recursion);
3404
3405	free_netdev(ppp->dev);
3406}
3407
3408/*
3409 * Locate an existing ppp unit.
3410 * The caller should have locked the all_ppp_mutex.
3411 */
3412static struct ppp *
3413ppp_find_unit(struct ppp_net *pn, int unit)
3414{
3415	return unit_find(&pn->units_idr, unit);
3416}
3417
3418/*
3419 * Locate an existing ppp channel.
3420 * The caller should have locked the all_channels_lock.
3421 * First we look in the new_channels list, then in the
3422 * all_channels list.  If found in the new_channels list,
3423 * we move it to the all_channels list.  This is for speed
3424 * when we have a lot of channels in use.
3425 */
3426static struct channel *
3427ppp_find_channel(struct ppp_net *pn, int unit)
3428{
3429	struct channel *pch;
3430
3431	list_for_each_entry(pch, &pn->new_channels, list) {
3432		if (pch->file.index == unit) {
3433			list_move(&pch->list, &pn->all_channels);
3434			return pch;
3435		}
3436	}
3437
3438	list_for_each_entry(pch, &pn->all_channels, list) {
3439		if (pch->file.index == unit)
3440			return pch;
3441	}
3442
3443	return NULL;
3444}
3445
3446/*
3447 * Connect a PPP channel to a PPP interface unit.
3448 */
3449static int
3450ppp_connect_channel(struct channel *pch, int unit)
3451{
3452	struct ppp *ppp;
3453	struct ppp_net *pn;
3454	int ret = -ENXIO;
3455	int hdrlen;
3456
3457	pn = ppp_pernet(pch->chan_net);
3458
3459	mutex_lock(&pn->all_ppp_mutex);
3460	ppp = ppp_find_unit(pn, unit);
3461	if (!ppp)
3462		goto out;
3463	write_lock_bh(&pch->upl);
3464	ret = -EINVAL;
3465	if (pch->ppp ||
3466	    rcu_dereference_protected(pch->bridge, lockdep_is_held(&pch->upl)))
3467		goto outl;
3468
3469	ppp_lock(ppp);
3470	spin_lock_bh(&pch->downl);
3471	if (!pch->chan) {
3472		/* Don't connect unregistered channels */
3473		spin_unlock_bh(&pch->downl);
3474		ppp_unlock(ppp);
3475		ret = -ENOTCONN;
3476		goto outl;
3477	}
3478	spin_unlock_bh(&pch->downl);
3479	if (pch->file.hdrlen > ppp->file.hdrlen)
3480		ppp->file.hdrlen = pch->file.hdrlen;
3481	hdrlen = pch->file.hdrlen + 2;	/* for protocol bytes */
3482	if (hdrlen > ppp->dev->hard_header_len)
3483		ppp->dev->hard_header_len = hdrlen;
3484	list_add_tail(&pch->clist, &ppp->channels);
3485	++ppp->n_channels;
3486	pch->ppp = ppp;
3487	refcount_inc(&ppp->file.refcnt);
3488	ppp_unlock(ppp);
3489	ret = 0;
3490
3491 outl:
3492	write_unlock_bh(&pch->upl);
3493 out:
3494	mutex_unlock(&pn->all_ppp_mutex);
3495	return ret;
3496}
3497
3498/*
3499 * Disconnect a channel from its ppp unit.
3500 */
3501static int
3502ppp_disconnect_channel(struct channel *pch)
3503{
3504	struct ppp *ppp;
3505	int err = -EINVAL;
3506
3507	write_lock_bh(&pch->upl);
3508	ppp = pch->ppp;
3509	pch->ppp = NULL;
3510	write_unlock_bh(&pch->upl);
3511	if (ppp) {
3512		/* remove it from the ppp unit's list */
3513		ppp_lock(ppp);
3514		list_del(&pch->clist);
3515		if (--ppp->n_channels == 0)
3516			wake_up_interruptible(&ppp->file.rwait);
3517		ppp_unlock(ppp);
3518		if (refcount_dec_and_test(&ppp->file.refcnt))
3519			ppp_destroy_interface(ppp);
3520		err = 0;
3521	}
3522	return err;
3523}
3524
3525/*
3526 * Free up the resources used by a ppp channel.
3527 */
3528static void ppp_destroy_channel(struct channel *pch)
3529{
3530	put_net_track(pch->chan_net, &pch->ns_tracker);
3531	pch->chan_net = NULL;
3532
3533	atomic_dec(&channel_count);
3534
3535	if (!pch->file.dead) {
3536		/* "can't happen" */
3537		pr_err("ppp: destroying undead channel %p !\n", pch);
3538		return;
3539	}
3540	skb_queue_purge(&pch->file.xq);
3541	skb_queue_purge(&pch->file.rq);
3542	kfree(pch);
3543}
3544
3545static void __exit ppp_cleanup(void)
3546{
3547	/* should never happen */
3548	if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
3549		pr_err("PPP: removing module but units remain!\n");
3550	rtnl_link_unregister(&ppp_link_ops);
3551	unregister_chrdev(PPP_MAJOR, "ppp");
3552	device_destroy(&ppp_class, MKDEV(PPP_MAJOR, 0));
3553	class_unregister(&ppp_class);
3554	unregister_pernet_device(&ppp_net_ops);
3555}
3556
3557/*
3558 * Units handling. Caller must protect concurrent access
3559 * by holding all_ppp_mutex
3560 */
3561
3562/* associate pointer with specified number */
3563static int unit_set(struct idr *p, void *ptr, int n)
3564{
3565	int unit;
3566
3567	unit = idr_alloc(p, ptr, n, n + 1, GFP_KERNEL);
3568	if (unit == -ENOSPC)
3569		unit = -EINVAL;
3570	return unit;
3571}
3572
3573/* get new free unit number and associate pointer with it */
3574static int unit_get(struct idr *p, void *ptr, int min)
3575{
3576	return idr_alloc(p, ptr, min, 0, GFP_KERNEL);
3577}
3578
3579/* put unit number back to a pool */
3580static void unit_put(struct idr *p, int n)
3581{
3582	idr_remove(p, n);
3583}
3584
3585/* get pointer associated with the number */
3586static void *unit_find(struct idr *p, int n)
3587{
3588	return idr_find(p, n);
3589}
3590
3591/* Module/initialization stuff */
3592
3593module_init(ppp_init);
3594module_exit(ppp_cleanup);
3595
3596EXPORT_SYMBOL(ppp_register_net_channel);
3597EXPORT_SYMBOL(ppp_register_channel);
3598EXPORT_SYMBOL(ppp_unregister_channel);
3599EXPORT_SYMBOL(ppp_channel_index);
3600EXPORT_SYMBOL(ppp_unit_number);
3601EXPORT_SYMBOL(ppp_dev_name);
3602EXPORT_SYMBOL(ppp_input);
3603EXPORT_SYMBOL(ppp_input_error);
3604EXPORT_SYMBOL(ppp_output_wakeup);
3605EXPORT_SYMBOL(ppp_register_compressor);
3606EXPORT_SYMBOL(ppp_unregister_compressor);
3607MODULE_DESCRIPTION("Generic PPP layer driver");
3608MODULE_LICENSE("GPL");
3609MODULE_ALIAS_CHARDEV(PPP_MAJOR, 0);
3610MODULE_ALIAS_RTNL_LINK("ppp");
3611MODULE_ALIAS("devname:ppp");
3612