Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl
[linux-2.6.git] / drivers / net / ppp_generic.c
1 /*
2  * Generic PPP layer for Linux.
3  *
4  * Copyright 1999-2002 Paul Mackerras.
5  *
6  *  This program is free software; you can redistribute it and/or
7  *  modify it under the terms of the GNU General Public License
8  *  as published by the Free Software Foundation; either version
9  *  2 of the License, or (at your option) any later version.
10  *
11  * The generic PPP layer handles the PPP network interfaces, the
12  * /dev/ppp device, packet and VJ compression, and multilink.
13  * It talks to PPP `channels' via the interface defined in
14  * include/linux/ppp_channel.h.  Channels provide the basic means for
15  * sending and receiving PPP frames on some kind of communications
16  * channel.
17  *
18  * Part of the code in this driver was inspired by the old async-only
19  * PPP driver, written by Michael Callahan and Al Longyear, and
20  * subsequently hacked by Paul Mackerras.
21  *
22  * ==FILEVERSION 20041108==
23  */
24
25 #include <linux/module.h>
26 #include <linux/kernel.h>
27 #include <linux/kmod.h>
28 #include <linux/init.h>
29 #include <linux/list.h>
30 #include <linux/idr.h>
31 #include <linux/netdevice.h>
32 #include <linux/poll.h>
33 #include <linux/ppp_defs.h>
34 #include <linux/filter.h>
35 #include <linux/if_ppp.h>
36 #include <linux/ppp_channel.h>
37 #include <linux/ppp-comp.h>
38 #include <linux/skbuff.h>
39 #include <linux/rtnetlink.h>
40 #include <linux/if_arp.h>
41 #include <linux/ip.h>
42 #include <linux/tcp.h>
43 #include <linux/spinlock.h>
44 #include <linux/rwsem.h>
45 #include <linux/stddef.h>
46 #include <linux/device.h>
47 #include <linux/mutex.h>
48 #include <linux/slab.h>
49 #include <net/slhc_vj.h>
50 #include <asm/atomic.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 /*
73  * An instance of /dev/ppp can be associated with either a ppp
74  * interface unit or a ppp channel.  In both cases, file->private_data
75  * points to one of these.
76  */
77 struct ppp_file {
78         enum {
79                 INTERFACE=1, CHANNEL
80         }               kind;
81         struct sk_buff_head xq;         /* pppd transmit queue */
82         struct sk_buff_head rq;         /* receive queue for pppd */
83         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
84         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
85         int             hdrlen;         /* space to leave for headers */
86         int             index;          /* interface unit / channel number */
87         int             dead;           /* unit/channel has been shut down */
88 };
89
90 #define PF_TO_X(pf, X)          container_of(pf, X, file)
91
92 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
93 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
94
95 /*
96  * Data structure describing one ppp unit.
97  * A ppp unit corresponds to a ppp network interface device
98  * and represents a multilink bundle.
99  * It can have 0 or more ppp channels connected to it.
100  */
101 struct ppp {
102         struct ppp_file file;           /* stuff for read/write/poll 0 */
103         struct file     *owner;         /* file that owns this unit 48 */
104         struct list_head channels;      /* list of attached channels 4c */
105         int             n_channels;     /* how many channels are attached 54 */
106         spinlock_t      rlock;          /* lock for receive side 58 */
107         spinlock_t      wlock;          /* lock for transmit side 5c */
108         int             mru;            /* max receive unit 60 */
109         unsigned int    flags;          /* control bits 64 */
110         unsigned int    xstate;         /* transmit state bits 68 */
111         unsigned int    rstate;         /* receive state bits 6c */
112         int             debug;          /* debug flags 70 */
113         struct slcompress *vj;          /* state for VJ header compression */
114         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
115         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
116         struct compressor *xcomp;       /* transmit packet compressor 8c */
117         void            *xc_state;      /* its internal state 90 */
118         struct compressor *rcomp;       /* receive decompressor 94 */
119         void            *rc_state;      /* its internal state 98 */
120         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
121         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
122         struct net_device *dev;         /* network interface device a4 */
123         int             closing;        /* is device closing down? a8 */
124 #ifdef CONFIG_PPP_MULTILINK
125         int             nxchan;         /* next channel to send something on */
126         u32             nxseq;          /* next sequence number to send */
127         int             mrru;           /* MP: max reconst. receive unit */
128         u32             nextseq;        /* MP: seq no of next packet */
129         u32             minseq;         /* MP: min of most recent seqnos */
130         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
131 #endif /* CONFIG_PPP_MULTILINK */
132 #ifdef CONFIG_PPP_FILTER
133         struct sock_filter *pass_filter;        /* filter for packets to pass */
134         struct sock_filter *active_filter;/* filter for pkts to reset idle */
135         unsigned pass_len, active_len;
136 #endif /* CONFIG_PPP_FILTER */
137         struct net      *ppp_net;       /* the net we belong to */
138 };
139
140 /*
141  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
142  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
143  * SC_MUST_COMP
144  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
145  * Bits in xstate: SC_COMP_RUN
146  */
147 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
148                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
149                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
150
151 /*
152  * Private data structure for each channel.
153  * This includes the data structure used for multilink.
154  */
155 struct channel {
156         struct ppp_file file;           /* stuff for read/write/poll */
157         struct list_head list;          /* link in all/new_channels list */
158         struct ppp_channel *chan;       /* public channel data structure */
159         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
160         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
161         struct ppp      *ppp;           /* ppp unit we're connected to */
162         struct net      *chan_net;      /* the net channel belongs to */
163         struct list_head clist;         /* link in list of channels per unit */
164         rwlock_t        upl;            /* protects `ppp' */
165 #ifdef CONFIG_PPP_MULTILINK
166         u8              avail;          /* flag used in multilink stuff */
167         u8              had_frag;       /* >= 1 fragments have been sent */
168         u32             lastseq;        /* MP: last sequence # received */
169         int             speed;          /* speed of the corresponding ppp channel*/
170 #endif /* CONFIG_PPP_MULTILINK */
171 };
172
173 /*
174  * SMP locking issues:
175  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
176  * list and the ppp.n_channels field, you need to take both locks
177  * before you modify them.
178  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
179  * channel.downl.
180  */
181
182 static DEFINE_MUTEX(ppp_mutex);
183 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
184 static atomic_t channel_count = ATOMIC_INIT(0);
185
186 /* per-net private data for this module */
187 static int ppp_net_id __read_mostly;
188 struct ppp_net {
189         /* units to ppp mapping */
190         struct idr units_idr;
191
192         /*
193          * all_ppp_mutex protects the units_idr mapping.
194          * It also ensures that finding a ppp unit in the units_idr
195          * map and updating its file.refcnt field is atomic.
196          */
197         struct mutex all_ppp_mutex;
198
199         /* channels */
200         struct list_head all_channels;
201         struct list_head new_channels;
202         int last_channel_index;
203
204         /*
205          * all_channels_lock protects all_channels and
206          * last_channel_index, and the atomicity of find
207          * a channel and updating its file.refcnt field.
208          */
209         spinlock_t all_channels_lock;
210 };
211
212 /* Get the PPP protocol number from a skb */
213 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
214
215 /* We limit the length of ppp->file.rq to this (arbitrary) value */
216 #define PPP_MAX_RQLEN   32
217
218 /*
219  * Maximum number of multilink fragments queued up.
220  * This has to be large enough to cope with the maximum latency of
221  * the slowest channel relative to the others.  Strictly it should
222  * depend on the number of channels and their characteristics.
223  */
224 #define PPP_MP_MAX_QLEN 128
225
226 /* Multilink header bits. */
227 #define B       0x80            /* this fragment begins a packet */
228 #define E       0x40            /* this fragment ends a packet */
229
230 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
231 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
232 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
233
234 /* Prototypes. */
235 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
236                         struct file *file, unsigned int cmd, unsigned long arg);
237 static void ppp_xmit_process(struct ppp *ppp);
238 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
239 static void ppp_push(struct ppp *ppp);
240 static void ppp_channel_push(struct channel *pch);
241 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
242                               struct channel *pch);
243 static void ppp_receive_error(struct ppp *ppp);
244 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
245 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
246                                             struct sk_buff *skb);
247 #ifdef CONFIG_PPP_MULTILINK
248 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
249                                 struct channel *pch);
250 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
251 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
252 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
253 #endif /* CONFIG_PPP_MULTILINK */
254 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
255 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
256 static void ppp_ccp_closed(struct ppp *ppp);
257 static struct compressor *find_compressor(int type);
258 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
259 static struct ppp *ppp_create_interface(struct net *net, int unit, int *retp);
260 static void init_ppp_file(struct ppp_file *pf, int kind);
261 static void ppp_shutdown_interface(struct ppp *ppp);
262 static void ppp_destroy_interface(struct ppp *ppp);
263 static struct ppp *ppp_find_unit(struct ppp_net *pn, int unit);
264 static struct channel *ppp_find_channel(struct ppp_net *pn, int unit);
265 static int ppp_connect_channel(struct channel *pch, int unit);
266 static int ppp_disconnect_channel(struct channel *pch);
267 static void ppp_destroy_channel(struct channel *pch);
268 static int unit_get(struct idr *p, void *ptr);
269 static int unit_set(struct idr *p, void *ptr, int n);
270 static void unit_put(struct idr *p, int n);
271 static void *unit_find(struct idr *p, int n);
272
273 static struct class *ppp_class;
274
275 /* per net-namespace data */
276 static inline struct ppp_net *ppp_pernet(struct net *net)
277 {
278         BUG_ON(!net);
279
280         return net_generic(net, ppp_net_id);
281 }
282
283 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
284 static inline int proto_to_npindex(int proto)
285 {
286         switch (proto) {
287         case PPP_IP:
288                 return NP_IP;
289         case PPP_IPV6:
290                 return NP_IPV6;
291         case PPP_IPX:
292                 return NP_IPX;
293         case PPP_AT:
294                 return NP_AT;
295         case PPP_MPLS_UC:
296                 return NP_MPLS_UC;
297         case PPP_MPLS_MC:
298                 return NP_MPLS_MC;
299         }
300         return -EINVAL;
301 }
302
303 /* Translates an NP index into a PPP protocol number */
304 static const int npindex_to_proto[NUM_NP] = {
305         PPP_IP,
306         PPP_IPV6,
307         PPP_IPX,
308         PPP_AT,
309         PPP_MPLS_UC,
310         PPP_MPLS_MC,
311 };
312
313 /* Translates an ethertype into an NP index */
314 static inline int ethertype_to_npindex(int ethertype)
315 {
316         switch (ethertype) {
317         case ETH_P_IP:
318                 return NP_IP;
319         case ETH_P_IPV6:
320                 return NP_IPV6;
321         case ETH_P_IPX:
322                 return NP_IPX;
323         case ETH_P_PPPTALK:
324         case ETH_P_ATALK:
325                 return NP_AT;
326         case ETH_P_MPLS_UC:
327                 return NP_MPLS_UC;
328         case ETH_P_MPLS_MC:
329                 return NP_MPLS_MC;
330         }
331         return -1;
332 }
333
334 /* Translates an NP index into an ethertype */
335 static const int npindex_to_ethertype[NUM_NP] = {
336         ETH_P_IP,
337         ETH_P_IPV6,
338         ETH_P_IPX,
339         ETH_P_PPPTALK,
340         ETH_P_MPLS_UC,
341         ETH_P_MPLS_MC,
342 };
343
344 /*
345  * Locking shorthand.
346  */
347 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
348 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
349 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
350 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
351 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
352                                      ppp_recv_lock(ppp); } while (0)
353 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
354                                      ppp_xmit_unlock(ppp); } while (0)
355
356 /*
357  * /dev/ppp device routines.
358  * The /dev/ppp device is used by pppd to control the ppp unit.
359  * It supports the read, write, ioctl and poll functions.
360  * Open instances of /dev/ppp can be in one of three states:
361  * unattached, attached to a ppp unit, or attached to a ppp channel.
362  */
363 static int ppp_open(struct inode *inode, struct file *file)
364 {
365         /*
366          * This could (should?) be enforced by the permissions on /dev/ppp.
367          */
368         if (!capable(CAP_NET_ADMIN))
369                 return -EPERM;
370         return 0;
371 }
372
373 static int ppp_release(struct inode *unused, struct file *file)
374 {
375         struct ppp_file *pf = file->private_data;
376         struct ppp *ppp;
377
378         if (pf) {
379                 file->private_data = NULL;
380                 if (pf->kind == INTERFACE) {
381                         ppp = PF_TO_PPP(pf);
382                         if (file == ppp->owner)
383                                 ppp_shutdown_interface(ppp);
384                 }
385                 if (atomic_dec_and_test(&pf->refcnt)) {
386                         switch (pf->kind) {
387                         case INTERFACE:
388                                 ppp_destroy_interface(PF_TO_PPP(pf));
389                                 break;
390                         case CHANNEL:
391                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
392                                 break;
393                         }
394                 }
395         }
396         return 0;
397 }
398
399 static ssize_t ppp_read(struct file *file, char __user *buf,
400                         size_t count, loff_t *ppos)
401 {
402         struct ppp_file *pf = file->private_data;
403         DECLARE_WAITQUEUE(wait, current);
404         ssize_t ret;
405         struct sk_buff *skb = NULL;
406         struct iovec iov;
407
408         ret = count;
409
410         if (!pf)
411                 return -ENXIO;
412         add_wait_queue(&pf->rwait, &wait);
413         for (;;) {
414                 set_current_state(TASK_INTERRUPTIBLE);
415                 skb = skb_dequeue(&pf->rq);
416                 if (skb)
417                         break;
418                 ret = 0;
419                 if (pf->dead)
420                         break;
421                 if (pf->kind == INTERFACE) {
422                         /*
423                          * Return 0 (EOF) on an interface that has no
424                          * channels connected, unless it is looping
425                          * network traffic (demand mode).
426                          */
427                         struct ppp *ppp = PF_TO_PPP(pf);
428                         if (ppp->n_channels == 0 &&
429                             (ppp->flags & SC_LOOP_TRAFFIC) == 0)
430                                 break;
431                 }
432                 ret = -EAGAIN;
433                 if (file->f_flags & O_NONBLOCK)
434                         break;
435                 ret = -ERESTARTSYS;
436                 if (signal_pending(current))
437                         break;
438                 schedule();
439         }
440         set_current_state(TASK_RUNNING);
441         remove_wait_queue(&pf->rwait, &wait);
442
443         if (!skb)
444                 goto out;
445
446         ret = -EOVERFLOW;
447         if (skb->len > count)
448                 goto outf;
449         ret = -EFAULT;
450         iov.iov_base = buf;
451         iov.iov_len = count;
452         if (skb_copy_datagram_iovec(skb, 0, &iov, skb->len))
453                 goto outf;
454         ret = skb->len;
455
456  outf:
457         kfree_skb(skb);
458  out:
459         return ret;
460 }
461
462 static ssize_t ppp_write(struct file *file, const char __user *buf,
463                          size_t count, loff_t *ppos)
464 {
465         struct ppp_file *pf = file->private_data;
466         struct sk_buff *skb;
467         ssize_t ret;
468
469         if (!pf)
470                 return -ENXIO;
471         ret = -ENOMEM;
472         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
473         if (!skb)
474                 goto out;
475         skb_reserve(skb, pf->hdrlen);
476         ret = -EFAULT;
477         if (copy_from_user(skb_put(skb, count), buf, count)) {
478                 kfree_skb(skb);
479                 goto out;
480         }
481
482         skb_queue_tail(&pf->xq, skb);
483
484         switch (pf->kind) {
485         case INTERFACE:
486                 ppp_xmit_process(PF_TO_PPP(pf));
487                 break;
488         case CHANNEL:
489                 ppp_channel_push(PF_TO_CHANNEL(pf));
490                 break;
491         }
492
493         ret = count;
494
495  out:
496         return ret;
497 }
498
499 /* No kernel lock - fine */
500 static unsigned int ppp_poll(struct file *file, poll_table *wait)
501 {
502         struct ppp_file *pf = file->private_data;
503         unsigned int mask;
504
505         if (!pf)
506                 return 0;
507         poll_wait(file, &pf->rwait, wait);
508         mask = POLLOUT | POLLWRNORM;
509         if (skb_peek(&pf->rq))
510                 mask |= POLLIN | POLLRDNORM;
511         if (pf->dead)
512                 mask |= POLLHUP;
513         else if (pf->kind == INTERFACE) {
514                 /* see comment in ppp_read */
515                 struct ppp *ppp = PF_TO_PPP(pf);
516                 if (ppp->n_channels == 0 &&
517                     (ppp->flags & SC_LOOP_TRAFFIC) == 0)
518                         mask |= POLLIN | POLLRDNORM;
519         }
520
521         return mask;
522 }
523
524 #ifdef CONFIG_PPP_FILTER
525 static int get_filter(void __user *arg, struct sock_filter **p)
526 {
527         struct sock_fprog uprog;
528         struct sock_filter *code = NULL;
529         int len, err;
530
531         if (copy_from_user(&uprog, arg, sizeof(uprog)))
532                 return -EFAULT;
533
534         if (!uprog.len) {
535                 *p = NULL;
536                 return 0;
537         }
538
539         len = uprog.len * sizeof(struct sock_filter);
540         code = memdup_user(uprog.filter, len);
541         if (IS_ERR(code))
542                 return PTR_ERR(code);
543
544         err = sk_chk_filter(code, uprog.len);
545         if (err) {
546                 kfree(code);
547                 return err;
548         }
549
550         *p = code;
551         return uprog.len;
552 }
553 #endif /* CONFIG_PPP_FILTER */
554
555 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
556 {
557         struct ppp_file *pf = file->private_data;
558         struct ppp *ppp;
559         int err = -EFAULT, val, val2, i;
560         struct ppp_idle idle;
561         struct npioctl npi;
562         int unit, cflags;
563         struct slcompress *vj;
564         void __user *argp = (void __user *)arg;
565         int __user *p = argp;
566
567         if (!pf)
568                 return ppp_unattached_ioctl(current->nsproxy->net_ns,
569                                         pf, file, cmd, arg);
570
571         if (cmd == PPPIOCDETACH) {
572                 /*
573                  * We have to be careful here... if the file descriptor
574                  * has been dup'd, we could have another process in the
575                  * middle of a poll using the same file *, so we had
576                  * better not free the interface data structures -
577                  * instead we fail the ioctl.  Even in this case, we
578                  * shut down the interface if we are the owner of it.
579                  * Actually, we should get rid of PPPIOCDETACH, userland
580                  * (i.e. pppd) could achieve the same effect by closing
581                  * this fd and reopening /dev/ppp.
582                  */
583                 err = -EINVAL;
584                 mutex_lock(&ppp_mutex);
585                 if (pf->kind == INTERFACE) {
586                         ppp = PF_TO_PPP(pf);
587                         if (file == ppp->owner)
588                                 ppp_shutdown_interface(ppp);
589                 }
590                 if (atomic_long_read(&file->f_count) <= 2) {
591                         ppp_release(NULL, file);
592                         err = 0;
593                 } else
594                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
595                                atomic_long_read(&file->f_count));
596                 mutex_unlock(&ppp_mutex);
597                 return err;
598         }
599
600         if (pf->kind == CHANNEL) {
601                 struct channel *pch;
602                 struct ppp_channel *chan;
603
604                 mutex_lock(&ppp_mutex);
605                 pch = PF_TO_CHANNEL(pf);
606
607                 switch (cmd) {
608                 case PPPIOCCONNECT:
609                         if (get_user(unit, p))
610                                 break;
611                         err = ppp_connect_channel(pch, unit);
612                         break;
613
614                 case PPPIOCDISCONN:
615                         err = ppp_disconnect_channel(pch);
616                         break;
617
618                 default:
619                         down_read(&pch->chan_sem);
620                         chan = pch->chan;
621                         err = -ENOTTY;
622                         if (chan && chan->ops->ioctl)
623                                 err = chan->ops->ioctl(chan, cmd, arg);
624                         up_read(&pch->chan_sem);
625                 }
626                 mutex_unlock(&ppp_mutex);
627                 return err;
628         }
629
630         if (pf->kind != INTERFACE) {
631                 /* can't happen */
632                 printk(KERN_ERR "PPP: not interface or channel??\n");
633                 return -EINVAL;
634         }
635
636         mutex_lock(&ppp_mutex);
637         ppp = PF_TO_PPP(pf);
638         switch (cmd) {
639         case PPPIOCSMRU:
640                 if (get_user(val, p))
641                         break;
642                 ppp->mru = val;
643                 err = 0;
644                 break;
645
646         case PPPIOCSFLAGS:
647                 if (get_user(val, p))
648                         break;
649                 ppp_lock(ppp);
650                 cflags = ppp->flags & ~val;
651                 ppp->flags = val & SC_FLAG_BITS;
652                 ppp_unlock(ppp);
653                 if (cflags & SC_CCP_OPEN)
654                         ppp_ccp_closed(ppp);
655                 err = 0;
656                 break;
657
658         case PPPIOCGFLAGS:
659                 val = ppp->flags | ppp->xstate | ppp->rstate;
660                 if (put_user(val, p))
661                         break;
662                 err = 0;
663                 break;
664
665         case PPPIOCSCOMPRESS:
666                 err = ppp_set_compress(ppp, arg);
667                 break;
668
669         case PPPIOCGUNIT:
670                 if (put_user(ppp->file.index, p))
671                         break;
672                 err = 0;
673                 break;
674
675         case PPPIOCSDEBUG:
676                 if (get_user(val, p))
677                         break;
678                 ppp->debug = val;
679                 err = 0;
680                 break;
681
682         case PPPIOCGDEBUG:
683                 if (put_user(ppp->debug, p))
684                         break;
685                 err = 0;
686                 break;
687
688         case PPPIOCGIDLE:
689                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
690                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
691                 if (copy_to_user(argp, &idle, sizeof(idle)))
692                         break;
693                 err = 0;
694                 break;
695
696         case PPPIOCSMAXCID:
697                 if (get_user(val, p))
698                         break;
699                 val2 = 15;
700                 if ((val >> 16) != 0) {
701                         val2 = val >> 16;
702                         val &= 0xffff;
703                 }
704                 vj = slhc_init(val2+1, val+1);
705                 if (!vj) {
706                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
707                         err = -ENOMEM;
708                         break;
709                 }
710                 ppp_lock(ppp);
711                 if (ppp->vj)
712                         slhc_free(ppp->vj);
713                 ppp->vj = vj;
714                 ppp_unlock(ppp);
715                 err = 0;
716                 break;
717
718         case PPPIOCGNPMODE:
719         case PPPIOCSNPMODE:
720                 if (copy_from_user(&npi, argp, sizeof(npi)))
721                         break;
722                 err = proto_to_npindex(npi.protocol);
723                 if (err < 0)
724                         break;
725                 i = err;
726                 if (cmd == PPPIOCGNPMODE) {
727                         err = -EFAULT;
728                         npi.mode = ppp->npmode[i];
729                         if (copy_to_user(argp, &npi, sizeof(npi)))
730                                 break;
731                 } else {
732                         ppp->npmode[i] = npi.mode;
733                         /* we may be able to transmit more packets now (??) */
734                         netif_wake_queue(ppp->dev);
735                 }
736                 err = 0;
737                 break;
738
739 #ifdef CONFIG_PPP_FILTER
740         case PPPIOCSPASS:
741         {
742                 struct sock_filter *code;
743                 err = get_filter(argp, &code);
744                 if (err >= 0) {
745                         ppp_lock(ppp);
746                         kfree(ppp->pass_filter);
747                         ppp->pass_filter = code;
748                         ppp->pass_len = err;
749                         ppp_unlock(ppp);
750                         err = 0;
751                 }
752                 break;
753         }
754         case PPPIOCSACTIVE:
755         {
756                 struct sock_filter *code;
757                 err = get_filter(argp, &code);
758                 if (err >= 0) {
759                         ppp_lock(ppp);
760                         kfree(ppp->active_filter);
761                         ppp->active_filter = code;
762                         ppp->active_len = err;
763                         ppp_unlock(ppp);
764                         err = 0;
765                 }
766                 break;
767         }
768 #endif /* CONFIG_PPP_FILTER */
769
770 #ifdef CONFIG_PPP_MULTILINK
771         case PPPIOCSMRRU:
772                 if (get_user(val, p))
773                         break;
774                 ppp_recv_lock(ppp);
775                 ppp->mrru = val;
776                 ppp_recv_unlock(ppp);
777                 err = 0;
778                 break;
779 #endif /* CONFIG_PPP_MULTILINK */
780
781         default:
782                 err = -ENOTTY;
783         }
784         mutex_unlock(&ppp_mutex);
785         return err;
786 }
787
788 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
789                         struct file *file, unsigned int cmd, unsigned long arg)
790 {
791         int unit, err = -EFAULT;
792         struct ppp *ppp;
793         struct channel *chan;
794         struct ppp_net *pn;
795         int __user *p = (int __user *)arg;
796
797         mutex_lock(&ppp_mutex);
798         switch (cmd) {
799         case PPPIOCNEWUNIT:
800                 /* Create a new ppp unit */
801                 if (get_user(unit, p))
802                         break;
803                 ppp = ppp_create_interface(net, unit, &err);
804                 if (!ppp)
805                         break;
806                 file->private_data = &ppp->file;
807                 ppp->owner = file;
808                 err = -EFAULT;
809                 if (put_user(ppp->file.index, p))
810                         break;
811                 err = 0;
812                 break;
813
814         case PPPIOCATTACH:
815                 /* Attach to an existing ppp unit */
816                 if (get_user(unit, p))
817                         break;
818                 err = -ENXIO;
819                 pn = ppp_pernet(net);
820                 mutex_lock(&pn->all_ppp_mutex);
821                 ppp = ppp_find_unit(pn, unit);
822                 if (ppp) {
823                         atomic_inc(&ppp->file.refcnt);
824                         file->private_data = &ppp->file;
825                         err = 0;
826                 }
827                 mutex_unlock(&pn->all_ppp_mutex);
828                 break;
829
830         case PPPIOCATTCHAN:
831                 if (get_user(unit, p))
832                         break;
833                 err = -ENXIO;
834                 pn = ppp_pernet(net);
835                 spin_lock_bh(&pn->all_channels_lock);
836                 chan = ppp_find_channel(pn, unit);
837                 if (chan) {
838                         atomic_inc(&chan->file.refcnt);
839                         file->private_data = &chan->file;
840                         err = 0;
841                 }
842                 spin_unlock_bh(&pn->all_channels_lock);
843                 break;
844
845         default:
846                 err = -ENOTTY;
847         }
848         mutex_unlock(&ppp_mutex);
849         return err;
850 }
851
852 static const struct file_operations ppp_device_fops = {
853         .owner          = THIS_MODULE,
854         .read           = ppp_read,
855         .write          = ppp_write,
856         .poll           = ppp_poll,
857         .unlocked_ioctl = ppp_ioctl,
858         .open           = ppp_open,
859         .release        = ppp_release,
860         .llseek         = noop_llseek,
861 };
862
863 static __net_init int ppp_init_net(struct net *net)
864 {
865         struct ppp_net *pn = net_generic(net, ppp_net_id);
866
867         idr_init(&pn->units_idr);
868         mutex_init(&pn->all_ppp_mutex);
869
870         INIT_LIST_HEAD(&pn->all_channels);
871         INIT_LIST_HEAD(&pn->new_channels);
872
873         spin_lock_init(&pn->all_channels_lock);
874
875         return 0;
876 }
877
878 static __net_exit void ppp_exit_net(struct net *net)
879 {
880         struct ppp_net *pn = net_generic(net, ppp_net_id);
881
882         idr_destroy(&pn->units_idr);
883 }
884
885 static struct pernet_operations ppp_net_ops = {
886         .init = ppp_init_net,
887         .exit = ppp_exit_net,
888         .id   = &ppp_net_id,
889         .size = sizeof(struct ppp_net),
890 };
891
892 #define PPP_MAJOR       108
893
894 /* Called at boot time if ppp is compiled into the kernel,
895    or at module load time (from init_module) if compiled as a module. */
896 static int __init ppp_init(void)
897 {
898         int err;
899
900         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
901
902         err = register_pernet_device(&ppp_net_ops);
903         if (err) {
904                 printk(KERN_ERR "failed to register PPP pernet device (%d)\n", err);
905                 goto out;
906         }
907
908         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
909         if (err) {
910                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
911                 goto out_net;
912         }
913
914         ppp_class = class_create(THIS_MODULE, "ppp");
915         if (IS_ERR(ppp_class)) {
916                 err = PTR_ERR(ppp_class);
917                 goto out_chrdev;
918         }
919
920         /* not a big deal if we fail here :-) */
921         device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
922
923         return 0;
924
925 out_chrdev:
926         unregister_chrdev(PPP_MAJOR, "ppp");
927 out_net:
928         unregister_pernet_device(&ppp_net_ops);
929 out:
930         return err;
931 }
932
933 /*
934  * Network interface unit routines.
935  */
936 static netdev_tx_t
937 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
938 {
939         struct ppp *ppp = netdev_priv(dev);
940         int npi, proto;
941         unsigned char *pp;
942
943         npi = ethertype_to_npindex(ntohs(skb->protocol));
944         if (npi < 0)
945                 goto outf;
946
947         /* Drop, accept or reject the packet */
948         switch (ppp->npmode[npi]) {
949         case NPMODE_PASS:
950                 break;
951         case NPMODE_QUEUE:
952                 /* it would be nice to have a way to tell the network
953                    system to queue this one up for later. */
954                 goto outf;
955         case NPMODE_DROP:
956         case NPMODE_ERROR:
957                 goto outf;
958         }
959
960         /* Put the 2-byte PPP protocol number on the front,
961            making sure there is room for the address and control fields. */
962         if (skb_cow_head(skb, PPP_HDRLEN))
963                 goto outf;
964
965         pp = skb_push(skb, 2);
966         proto = npindex_to_proto[npi];
967         pp[0] = proto >> 8;
968         pp[1] = proto;
969
970         netif_stop_queue(dev);
971         skb_queue_tail(&ppp->file.xq, skb);
972         ppp_xmit_process(ppp);
973         return NETDEV_TX_OK;
974
975  outf:
976         kfree_skb(skb);
977         ++dev->stats.tx_dropped;
978         return NETDEV_TX_OK;
979 }
980
981 static int
982 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
983 {
984         struct ppp *ppp = netdev_priv(dev);
985         int err = -EFAULT;
986         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
987         struct ppp_stats stats;
988         struct ppp_comp_stats cstats;
989         char *vers;
990
991         switch (cmd) {
992         case SIOCGPPPSTATS:
993                 ppp_get_stats(ppp, &stats);
994                 if (copy_to_user(addr, &stats, sizeof(stats)))
995                         break;
996                 err = 0;
997                 break;
998
999         case SIOCGPPPCSTATS:
1000                 memset(&cstats, 0, sizeof(cstats));
1001                 if (ppp->xc_state)
1002                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
1003                 if (ppp->rc_state)
1004                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
1005                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
1006                         break;
1007                 err = 0;
1008                 break;
1009
1010         case SIOCGPPPVER:
1011                 vers = PPP_VERSION;
1012                 if (copy_to_user(addr, vers, strlen(vers) + 1))
1013                         break;
1014                 err = 0;
1015                 break;
1016
1017         default:
1018                 err = -EINVAL;
1019         }
1020
1021         return err;
1022 }
1023
1024 static const struct net_device_ops ppp_netdev_ops = {
1025         .ndo_start_xmit = ppp_start_xmit,
1026         .ndo_do_ioctl   = ppp_net_ioctl,
1027 };
1028
1029 static void ppp_setup(struct net_device *dev)
1030 {
1031         dev->netdev_ops = &ppp_netdev_ops;
1032         dev->hard_header_len = PPP_HDRLEN;
1033         dev->mtu = PPP_MTU;
1034         dev->addr_len = 0;
1035         dev->tx_queue_len = 3;
1036         dev->type = ARPHRD_PPP;
1037         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1038         dev->features |= NETIF_F_NETNS_LOCAL;
1039         dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
1040 }
1041
1042 /*
1043  * Transmit-side routines.
1044  */
1045
1046 /*
1047  * Called to do any work queued up on the transmit side
1048  * that can now be done.
1049  */
1050 static void
1051 ppp_xmit_process(struct ppp *ppp)
1052 {
1053         struct sk_buff *skb;
1054
1055         ppp_xmit_lock(ppp);
1056         if (!ppp->closing) {
1057                 ppp_push(ppp);
1058                 while (!ppp->xmit_pending &&
1059                        (skb = skb_dequeue(&ppp->file.xq)))
1060                         ppp_send_frame(ppp, skb);
1061                 /* If there's no work left to do, tell the core net
1062                    code that we can accept some more. */
1063                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1064                         netif_wake_queue(ppp->dev);
1065         }
1066         ppp_xmit_unlock(ppp);
1067 }
1068
1069 static inline struct sk_buff *
1070 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1071 {
1072         struct sk_buff *new_skb;
1073         int len;
1074         int new_skb_size = ppp->dev->mtu +
1075                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1076         int compressor_skb_size = ppp->dev->mtu +
1077                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1078         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1079         if (!new_skb) {
1080                 if (net_ratelimit())
1081                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1082                 return NULL;
1083         }
1084         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1085                 skb_reserve(new_skb,
1086                             ppp->dev->hard_header_len - PPP_HDRLEN);
1087
1088         /* compressor still expects A/C bytes in hdr */
1089         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1090                                    new_skb->data, skb->len + 2,
1091                                    compressor_skb_size);
1092         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1093                 kfree_skb(skb);
1094                 skb = new_skb;
1095                 skb_put(skb, len);
1096                 skb_pull(skb, 2);       /* pull off A/C bytes */
1097         } else if (len == 0) {
1098                 /* didn't compress, or CCP not up yet */
1099                 kfree_skb(new_skb);
1100                 new_skb = skb;
1101         } else {
1102                 /*
1103                  * (len < 0)
1104                  * MPPE requires that we do not send unencrypted
1105                  * frames.  The compressor will return -1 if we
1106                  * should drop the frame.  We cannot simply test
1107                  * the compress_proto because MPPE and MPPC share
1108                  * the same number.
1109                  */
1110                 if (net_ratelimit())
1111                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1112                 kfree_skb(skb);
1113                 kfree_skb(new_skb);
1114                 new_skb = NULL;
1115         }
1116         return new_skb;
1117 }
1118
1119 /*
1120  * Compress and send a frame.
1121  * The caller should have locked the xmit path,
1122  * and xmit_pending should be 0.
1123  */
1124 static void
1125 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1126 {
1127         int proto = PPP_PROTO(skb);
1128         struct sk_buff *new_skb;
1129         int len;
1130         unsigned char *cp;
1131
1132         if (proto < 0x8000) {
1133 #ifdef CONFIG_PPP_FILTER
1134                 /* check if we should pass this packet */
1135                 /* the filter instructions are constructed assuming
1136                    a four-byte PPP header on each packet */
1137                 *skb_push(skb, 2) = 1;
1138                 if (ppp->pass_filter &&
1139                     sk_run_filter(skb, ppp->pass_filter,
1140                                   ppp->pass_len) == 0) {
1141                         if (ppp->debug & 1)
1142                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1143                         kfree_skb(skb);
1144                         return;
1145                 }
1146                 /* if this packet passes the active filter, record the time */
1147                 if (!(ppp->active_filter &&
1148                       sk_run_filter(skb, ppp->active_filter,
1149                                     ppp->active_len) == 0))
1150                         ppp->last_xmit = jiffies;
1151                 skb_pull(skb, 2);
1152 #else
1153                 /* for data packets, record the time */
1154                 ppp->last_xmit = jiffies;
1155 #endif /* CONFIG_PPP_FILTER */
1156         }
1157
1158         ++ppp->dev->stats.tx_packets;
1159         ppp->dev->stats.tx_bytes += skb->len - 2;
1160
1161         switch (proto) {
1162         case PPP_IP:
1163                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1164                         break;
1165                 /* try to do VJ TCP header compression */
1166                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1167                                     GFP_ATOMIC);
1168                 if (!new_skb) {
1169                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1170                         goto drop;
1171                 }
1172                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1173                 cp = skb->data + 2;
1174                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1175                                     new_skb->data + 2, &cp,
1176                                     !(ppp->flags & SC_NO_TCP_CCID));
1177                 if (cp == skb->data + 2) {
1178                         /* didn't compress */
1179                         kfree_skb(new_skb);
1180                 } else {
1181                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1182                                 proto = PPP_VJC_COMP;
1183                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1184                         } else {
1185                                 proto = PPP_VJC_UNCOMP;
1186                                 cp[0] = skb->data[2];
1187                         }
1188                         kfree_skb(skb);
1189                         skb = new_skb;
1190                         cp = skb_put(skb, len + 2);
1191                         cp[0] = 0;
1192                         cp[1] = proto;
1193                 }
1194                 break;
1195
1196         case PPP_CCP:
1197                 /* peek at outbound CCP frames */
1198                 ppp_ccp_peek(ppp, skb, 0);
1199                 break;
1200         }
1201
1202         /* try to do packet compression */
1203         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state &&
1204             proto != PPP_LCP && proto != PPP_CCP) {
1205                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1206                         if (net_ratelimit())
1207                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1208                         goto drop;
1209                 }
1210                 skb = pad_compress_skb(ppp, skb);
1211                 if (!skb)
1212                         goto drop;
1213         }
1214
1215         /*
1216          * If we are waiting for traffic (demand dialling),
1217          * queue it up for pppd to receive.
1218          */
1219         if (ppp->flags & SC_LOOP_TRAFFIC) {
1220                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1221                         goto drop;
1222                 skb_queue_tail(&ppp->file.rq, skb);
1223                 wake_up_interruptible(&ppp->file.rwait);
1224                 return;
1225         }
1226
1227         ppp->xmit_pending = skb;
1228         ppp_push(ppp);
1229         return;
1230
1231  drop:
1232         kfree_skb(skb);
1233         ++ppp->dev->stats.tx_errors;
1234 }
1235
1236 /*
1237  * Try to send the frame in xmit_pending.
1238  * The caller should have the xmit path locked.
1239  */
1240 static void
1241 ppp_push(struct ppp *ppp)
1242 {
1243         struct list_head *list;
1244         struct channel *pch;
1245         struct sk_buff *skb = ppp->xmit_pending;
1246
1247         if (!skb)
1248                 return;
1249
1250         list = &ppp->channels;
1251         if (list_empty(list)) {
1252                 /* nowhere to send the packet, just drop it */
1253                 ppp->xmit_pending = NULL;
1254                 kfree_skb(skb);
1255                 return;
1256         }
1257
1258         if ((ppp->flags & SC_MULTILINK) == 0) {
1259                 /* not doing multilink: send it down the first channel */
1260                 list = list->next;
1261                 pch = list_entry(list, struct channel, clist);
1262
1263                 spin_lock_bh(&pch->downl);
1264                 if (pch->chan) {
1265                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1266                                 ppp->xmit_pending = NULL;
1267                 } else {
1268                         /* channel got unregistered */
1269                         kfree_skb(skb);
1270                         ppp->xmit_pending = NULL;
1271                 }
1272                 spin_unlock_bh(&pch->downl);
1273                 return;
1274         }
1275
1276 #ifdef CONFIG_PPP_MULTILINK
1277         /* Multilink: fragment the packet over as many links
1278            as can take the packet at the moment. */
1279         if (!ppp_mp_explode(ppp, skb))
1280                 return;
1281 #endif /* CONFIG_PPP_MULTILINK */
1282
1283         ppp->xmit_pending = NULL;
1284         kfree_skb(skb);
1285 }
1286
1287 #ifdef CONFIG_PPP_MULTILINK
1288 /*
1289  * Divide a packet to be transmitted into fragments and
1290  * send them out the individual links.
1291  */
1292 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1293 {
1294         int len, totlen;
1295         int i, bits, hdrlen, mtu;
1296         int flen;
1297         int navail, nfree, nzero;
1298         int nbigger;
1299         int totspeed;
1300         int totfree;
1301         unsigned char *p, *q;
1302         struct list_head *list;
1303         struct channel *pch;
1304         struct sk_buff *frag;
1305         struct ppp_channel *chan;
1306
1307         totspeed = 0; /*total bitrate of the bundle*/
1308         nfree = 0; /* # channels which have no packet already queued */
1309         navail = 0; /* total # of usable channels (not deregistered) */
1310         nzero = 0; /* number of channels with zero speed associated*/
1311         totfree = 0; /*total # of channels available and
1312                                   *having no queued packets before
1313                                   *starting the fragmentation*/
1314
1315         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1316         i = 0;
1317         list_for_each_entry(pch, &ppp->channels, clist) {
1318                 if (pch->chan) {
1319                         pch->avail = 1;
1320                         navail++;
1321                         pch->speed = pch->chan->speed;
1322                 } else {
1323                         pch->avail = 0;
1324                 }
1325                 if (pch->avail) {
1326                         if (skb_queue_empty(&pch->file.xq) ||
1327                                 !pch->had_frag) {
1328                                         if (pch->speed == 0)
1329                                                 nzero++;
1330                                         else
1331                                                 totspeed += pch->speed;
1332
1333                                         pch->avail = 2;
1334                                         ++nfree;
1335                                         ++totfree;
1336                                 }
1337                         if (!pch->had_frag && i < ppp->nxchan)
1338                                 ppp->nxchan = i;
1339                 }
1340                 ++i;
1341         }
1342         /*
1343          * Don't start sending this packet unless at least half of
1344          * the channels are free.  This gives much better TCP
1345          * performance if we have a lot of channels.
1346          */
1347         if (nfree == 0 || nfree < navail / 2)
1348                 return 0; /* can't take now, leave it in xmit_pending */
1349
1350         /* Do protocol field compression (XXX this should be optional) */
1351         p = skb->data;
1352         len = skb->len;
1353         if (*p == 0) {
1354                 ++p;
1355                 --len;
1356         }
1357
1358         totlen = len;
1359         nbigger = len % nfree;
1360
1361         /* skip to the channel after the one we last used
1362            and start at that one */
1363         list = &ppp->channels;
1364         for (i = 0; i < ppp->nxchan; ++i) {
1365                 list = list->next;
1366                 if (list == &ppp->channels) {
1367                         i = 0;
1368                         break;
1369                 }
1370         }
1371
1372         /* create a fragment for each channel */
1373         bits = B;
1374         while (len > 0) {
1375                 list = list->next;
1376                 if (list == &ppp->channels) {
1377                         i = 0;
1378                         continue;
1379                 }
1380                 pch = list_entry(list, struct channel, clist);
1381                 ++i;
1382                 if (!pch->avail)
1383                         continue;
1384
1385                 /*
1386                  * Skip this channel if it has a fragment pending already and
1387                  * we haven't given a fragment to all of the free channels.
1388                  */
1389                 if (pch->avail == 1) {
1390                         if (nfree > 0)
1391                                 continue;
1392                 } else {
1393                         pch->avail = 1;
1394                 }
1395
1396                 /* check the channel's mtu and whether it is still attached. */
1397                 spin_lock_bh(&pch->downl);
1398                 if (pch->chan == NULL) {
1399                         /* can't use this channel, it's being deregistered */
1400                         if (pch->speed == 0)
1401                                 nzero--;
1402                         else
1403                                 totspeed -= pch->speed;
1404
1405                         spin_unlock_bh(&pch->downl);
1406                         pch->avail = 0;
1407                         totlen = len;
1408                         totfree--;
1409                         nfree--;
1410                         if (--navail == 0)
1411                                 break;
1412                         continue;
1413                 }
1414
1415                 /*
1416                 *if the channel speed is not set divide
1417                 *the packet evenly among the free channels;
1418                 *otherwise divide it according to the speed
1419                 *of the channel we are going to transmit on
1420                 */
1421                 flen = len;
1422                 if (nfree > 0) {
1423                         if (pch->speed == 0) {
1424                                 flen = len/nfree;
1425                                 if (nbigger > 0) {
1426                                         flen++;
1427                                         nbigger--;
1428                                 }
1429                         } else {
1430                                 flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
1431                                         ((totspeed*totfree)/pch->speed)) - hdrlen;
1432                                 if (nbigger > 0) {
1433                                         flen += ((totfree - nzero)*pch->speed)/totspeed;
1434                                         nbigger -= ((totfree - nzero)*pch->speed)/
1435                                                         totspeed;
1436                                 }
1437                         }
1438                         nfree--;
1439                 }
1440
1441                 /*
1442                  *check if we are on the last channel or
1443                  *we exceded the lenght of the data to
1444                  *fragment
1445                  */
1446                 if ((nfree <= 0) || (flen > len))
1447                         flen = len;
1448                 /*
1449                  *it is not worth to tx on slow channels:
1450                  *in that case from the resulting flen according to the
1451                  *above formula will be equal or less than zero.
1452                  *Skip the channel in this case
1453                  */
1454                 if (flen <= 0) {
1455                         pch->avail = 2;
1456                         spin_unlock_bh(&pch->downl);
1457                         continue;
1458                 }
1459
1460                 mtu = pch->chan->mtu - hdrlen;
1461                 if (mtu < 4)
1462                         mtu = 4;
1463                 if (flen > mtu)
1464                         flen = mtu;
1465                 if (flen == len)
1466                         bits |= E;
1467                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1468                 if (!frag)
1469                         goto noskb;
1470                 q = skb_put(frag, flen + hdrlen);
1471
1472                 /* make the MP header */
1473                 q[0] = PPP_MP >> 8;
1474                 q[1] = PPP_MP;
1475                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1476                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1477                         q[3] = ppp->nxseq;
1478                 } else {
1479                         q[2] = bits;
1480                         q[3] = ppp->nxseq >> 16;
1481                         q[4] = ppp->nxseq >> 8;
1482                         q[5] = ppp->nxseq;
1483                 }
1484
1485                 memcpy(q + hdrlen, p, flen);
1486
1487                 /* try to send it down the channel */
1488                 chan = pch->chan;
1489                 if (!skb_queue_empty(&pch->file.xq) ||
1490                         !chan->ops->start_xmit(chan, frag))
1491                         skb_queue_tail(&pch->file.xq, frag);
1492                 pch->had_frag = 1;
1493                 p += flen;
1494                 len -= flen;
1495                 ++ppp->nxseq;
1496                 bits = 0;
1497                 spin_unlock_bh(&pch->downl);
1498         }
1499         ppp->nxchan = i;
1500
1501         return 1;
1502
1503  noskb:
1504         spin_unlock_bh(&pch->downl);
1505         if (ppp->debug & 1)
1506                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1507         ++ppp->dev->stats.tx_errors;
1508         ++ppp->nxseq;
1509         return 1;       /* abandon the frame */
1510 }
1511 #endif /* CONFIG_PPP_MULTILINK */
1512
1513 /*
1514  * Try to send data out on a channel.
1515  */
1516 static void
1517 ppp_channel_push(struct channel *pch)
1518 {
1519         struct sk_buff *skb;
1520         struct ppp *ppp;
1521
1522         spin_lock_bh(&pch->downl);
1523         if (pch->chan) {
1524                 while (!skb_queue_empty(&pch->file.xq)) {
1525                         skb = skb_dequeue(&pch->file.xq);
1526                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1527                                 /* put the packet back and try again later */
1528                                 skb_queue_head(&pch->file.xq, skb);
1529                                 break;
1530                         }
1531                 }
1532         } else {
1533                 /* channel got deregistered */
1534                 skb_queue_purge(&pch->file.xq);
1535         }
1536         spin_unlock_bh(&pch->downl);
1537         /* see if there is anything from the attached unit to be sent */
1538         if (skb_queue_empty(&pch->file.xq)) {
1539                 read_lock_bh(&pch->upl);
1540                 ppp = pch->ppp;
1541                 if (ppp)
1542                         ppp_xmit_process(ppp);
1543                 read_unlock_bh(&pch->upl);
1544         }
1545 }
1546
1547 /*
1548  * Receive-side routines.
1549  */
1550
1551 /* misuse a few fields of the skb for MP reconstruction */
1552 #define sequence        priority
1553 #define BEbits          cb[0]
1554
1555 static inline void
1556 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1557 {
1558         ppp_recv_lock(ppp);
1559         if (!ppp->closing)
1560                 ppp_receive_frame(ppp, skb, pch);
1561         else
1562                 kfree_skb(skb);
1563         ppp_recv_unlock(ppp);
1564 }
1565
1566 void
1567 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1568 {
1569         struct channel *pch = chan->ppp;
1570         int proto;
1571
1572         if (!pch) {
1573                 kfree_skb(skb);
1574                 return;
1575         }
1576
1577         read_lock_bh(&pch->upl);
1578         if (!pskb_may_pull(skb, 2)) {
1579                 kfree_skb(skb);
1580                 if (pch->ppp) {
1581                         ++pch->ppp->dev->stats.rx_length_errors;
1582                         ppp_receive_error(pch->ppp);
1583                 }
1584                 goto done;
1585         }
1586
1587         proto = PPP_PROTO(skb);
1588         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1589                 /* put it on the channel queue */
1590                 skb_queue_tail(&pch->file.rq, skb);
1591                 /* drop old frames if queue too long */
1592                 while (pch->file.rq.qlen > PPP_MAX_RQLEN &&
1593                        (skb = skb_dequeue(&pch->file.rq)))
1594                         kfree_skb(skb);
1595                 wake_up_interruptible(&pch->file.rwait);
1596         } else {
1597                 ppp_do_recv(pch->ppp, skb, pch);
1598         }
1599
1600 done:
1601         read_unlock_bh(&pch->upl);
1602 }
1603
1604 /* Put a 0-length skb in the receive queue as an error indication */
1605 void
1606 ppp_input_error(struct ppp_channel *chan, int code)
1607 {
1608         struct channel *pch = chan->ppp;
1609         struct sk_buff *skb;
1610
1611         if (!pch)
1612                 return;
1613
1614         read_lock_bh(&pch->upl);
1615         if (pch->ppp) {
1616                 skb = alloc_skb(0, GFP_ATOMIC);
1617                 if (skb) {
1618                         skb->len = 0;           /* probably unnecessary */
1619                         skb->cb[0] = code;
1620                         ppp_do_recv(pch->ppp, skb, pch);
1621                 }
1622         }
1623         read_unlock_bh(&pch->upl);
1624 }
1625
1626 /*
1627  * We come in here to process a received frame.
1628  * The receive side of the ppp unit is locked.
1629  */
1630 static void
1631 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1632 {
1633         /* note: a 0-length skb is used as an error indication */
1634         if (skb->len > 0) {
1635 #ifdef CONFIG_PPP_MULTILINK
1636                 /* XXX do channel-level decompression here */
1637                 if (PPP_PROTO(skb) == PPP_MP)
1638                         ppp_receive_mp_frame(ppp, skb, pch);
1639                 else
1640 #endif /* CONFIG_PPP_MULTILINK */
1641                         ppp_receive_nonmp_frame(ppp, skb);
1642         } else {
1643                 kfree_skb(skb);
1644                 ppp_receive_error(ppp);
1645         }
1646 }
1647
1648 static void
1649 ppp_receive_error(struct ppp *ppp)
1650 {
1651         ++ppp->dev->stats.rx_errors;
1652         if (ppp->vj)
1653                 slhc_toss(ppp->vj);
1654 }
1655
1656 static void
1657 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1658 {
1659         struct sk_buff *ns;
1660         int proto, len, npi;
1661
1662         /*
1663          * Decompress the frame, if compressed.
1664          * Note that some decompressors need to see uncompressed frames
1665          * that come in as well as compressed frames.
1666          */
1667         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN) &&
1668             (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1669                 skb = ppp_decompress_frame(ppp, skb);
1670
1671         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1672                 goto err;
1673
1674         proto = PPP_PROTO(skb);
1675         switch (proto) {
1676         case PPP_VJC_COMP:
1677                 /* decompress VJ compressed packets */
1678                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1679                         goto err;
1680
1681                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1682                         /* copy to a new sk_buff with more tailroom */
1683                         ns = dev_alloc_skb(skb->len + 128);
1684                         if (!ns) {
1685                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1686                                 goto err;
1687                         }
1688                         skb_reserve(ns, 2);
1689                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1690                         kfree_skb(skb);
1691                         skb = ns;
1692                 }
1693                 else
1694                         skb->ip_summed = CHECKSUM_NONE;
1695
1696                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1697                 if (len <= 0) {
1698                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1699                         goto err;
1700                 }
1701                 len += 2;
1702                 if (len > skb->len)
1703                         skb_put(skb, len - skb->len);
1704                 else if (len < skb->len)
1705                         skb_trim(skb, len);
1706                 proto = PPP_IP;
1707                 break;
1708
1709         case PPP_VJC_UNCOMP:
1710                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1711                         goto err;
1712
1713                 /* Until we fix the decompressor need to make sure
1714                  * data portion is linear.
1715                  */
1716                 if (!pskb_may_pull(skb, skb->len))
1717                         goto err;
1718
1719                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1720                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1721                         goto err;
1722                 }
1723                 proto = PPP_IP;
1724                 break;
1725
1726         case PPP_CCP:
1727                 ppp_ccp_peek(ppp, skb, 1);
1728                 break;
1729         }
1730
1731         ++ppp->dev->stats.rx_packets;
1732         ppp->dev->stats.rx_bytes += skb->len - 2;
1733
1734         npi = proto_to_npindex(proto);
1735         if (npi < 0) {
1736                 /* control or unknown frame - pass it to pppd */
1737                 skb_queue_tail(&ppp->file.rq, skb);
1738                 /* limit queue length by dropping old frames */
1739                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN &&
1740                        (skb = skb_dequeue(&ppp->file.rq)))
1741                         kfree_skb(skb);
1742                 /* wake up any process polling or blocking on read */
1743                 wake_up_interruptible(&ppp->file.rwait);
1744
1745         } else {
1746                 /* network protocol frame - give it to the kernel */
1747
1748 #ifdef CONFIG_PPP_FILTER
1749                 /* check if the packet passes the pass and active filters */
1750                 /* the filter instructions are constructed assuming
1751                    a four-byte PPP header on each packet */
1752                 if (ppp->pass_filter || ppp->active_filter) {
1753                         if (skb_cloned(skb) &&
1754                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1755                                 goto err;
1756
1757                         *skb_push(skb, 2) = 0;
1758                         if (ppp->pass_filter &&
1759                             sk_run_filter(skb, ppp->pass_filter,
1760                                           ppp->pass_len) == 0) {
1761                                 if (ppp->debug & 1)
1762                                         printk(KERN_DEBUG "PPP: inbound frame "
1763                                                "not passed\n");
1764                                 kfree_skb(skb);
1765                                 return;
1766                         }
1767                         if (!(ppp->active_filter &&
1768                               sk_run_filter(skb, ppp->active_filter,
1769                                             ppp->active_len) == 0))
1770                                 ppp->last_recv = jiffies;
1771                         __skb_pull(skb, 2);
1772                 } else
1773 #endif /* CONFIG_PPP_FILTER */
1774                         ppp->last_recv = jiffies;
1775
1776                 if ((ppp->dev->flags & IFF_UP) == 0 ||
1777                     ppp->npmode[npi] != NPMODE_PASS) {
1778                         kfree_skb(skb);
1779                 } else {
1780                         /* chop off protocol */
1781                         skb_pull_rcsum(skb, 2);
1782                         skb->dev = ppp->dev;
1783                         skb->protocol = htons(npindex_to_ethertype[npi]);
1784                         skb_reset_mac_header(skb);
1785                         netif_rx(skb);
1786                 }
1787         }
1788         return;
1789
1790  err:
1791         kfree_skb(skb);
1792         ppp_receive_error(ppp);
1793 }
1794
1795 static struct sk_buff *
1796 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1797 {
1798         int proto = PPP_PROTO(skb);
1799         struct sk_buff *ns;
1800         int len;
1801
1802         /* Until we fix all the decompressor's need to make sure
1803          * data portion is linear.
1804          */
1805         if (!pskb_may_pull(skb, skb->len))
1806                 goto err;
1807
1808         if (proto == PPP_COMP) {
1809                 int obuff_size;
1810
1811                 switch(ppp->rcomp->compress_proto) {
1812                 case CI_MPPE:
1813                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1814                         break;
1815                 default:
1816                         obuff_size = ppp->mru + PPP_HDRLEN;
1817                         break;
1818                 }
1819
1820                 ns = dev_alloc_skb(obuff_size);
1821                 if (!ns) {
1822                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1823                         goto err;
1824                 }
1825                 /* the decompressor still expects the A/C bytes in the hdr */
1826                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1827                                 skb->len + 2, ns->data, obuff_size);
1828                 if (len < 0) {
1829                         /* Pass the compressed frame to pppd as an
1830                            error indication. */
1831                         if (len == DECOMP_FATALERROR)
1832                                 ppp->rstate |= SC_DC_FERROR;
1833                         kfree_skb(ns);
1834                         goto err;
1835                 }
1836
1837                 kfree_skb(skb);
1838                 skb = ns;
1839                 skb_put(skb, len);
1840                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1841
1842         } else {
1843                 /* Uncompressed frame - pass to decompressor so it
1844                    can update its dictionary if necessary. */
1845                 if (ppp->rcomp->incomp)
1846                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1847                                            skb->len + 2);
1848         }
1849
1850         return skb;
1851
1852  err:
1853         ppp->rstate |= SC_DC_ERROR;
1854         ppp_receive_error(ppp);
1855         return skb;
1856 }
1857
1858 #ifdef CONFIG_PPP_MULTILINK
1859 /*
1860  * Receive a multilink frame.
1861  * We put it on the reconstruction queue and then pull off
1862  * as many completed frames as we can.
1863  */
1864 static void
1865 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1866 {
1867         u32 mask, seq;
1868         struct channel *ch;
1869         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1870
1871         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1872                 goto err;               /* no good, throw it away */
1873
1874         /* Decode sequence number and begin/end bits */
1875         if (ppp->flags & SC_MP_SHORTSEQ) {
1876                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1877                 mask = 0xfff;
1878         } else {
1879                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1880                 mask = 0xffffff;
1881         }
1882         skb->BEbits = skb->data[2];
1883         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1884
1885         /*
1886          * Do protocol ID decompression on the first fragment of each packet.
1887          */
1888         if ((skb->BEbits & B) && (skb->data[0] & 1))
1889                 *skb_push(skb, 1) = 0;
1890
1891         /*
1892          * Expand sequence number to 32 bits, making it as close
1893          * as possible to ppp->minseq.
1894          */
1895         seq |= ppp->minseq & ~mask;
1896         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1897                 seq += mask + 1;
1898         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1899                 seq -= mask + 1;        /* should never happen */
1900         skb->sequence = seq;
1901         pch->lastseq = seq;
1902
1903         /*
1904          * If this packet comes before the next one we were expecting,
1905          * drop it.
1906          */
1907         if (seq_before(seq, ppp->nextseq)) {
1908                 kfree_skb(skb);
1909                 ++ppp->dev->stats.rx_dropped;
1910                 ppp_receive_error(ppp);
1911                 return;
1912         }
1913
1914         /*
1915          * Reevaluate minseq, the minimum over all channels of the
1916          * last sequence number received on each channel.  Because of
1917          * the increasing sequence number rule, we know that any fragment
1918          * before `minseq' which hasn't arrived is never going to arrive.
1919          * The list of channels can't change because we have the receive
1920          * side of the ppp unit locked.
1921          */
1922         list_for_each_entry(ch, &ppp->channels, clist) {
1923                 if (seq_before(ch->lastseq, seq))
1924                         seq = ch->lastseq;
1925         }
1926         if (seq_before(ppp->minseq, seq))
1927                 ppp->minseq = seq;
1928
1929         /* Put the fragment on the reconstruction queue */
1930         ppp_mp_insert(ppp, skb);
1931
1932         /* If the queue is getting long, don't wait any longer for packets
1933            before the start of the queue. */
1934         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
1935                 struct sk_buff *mskb = skb_peek(&ppp->mrq);
1936                 if (seq_before(ppp->minseq, mskb->sequence))
1937                         ppp->minseq = mskb->sequence;
1938         }
1939
1940         /* Pull completed packets off the queue and receive them. */
1941         while ((skb = ppp_mp_reconstruct(ppp))) {
1942                 if (pskb_may_pull(skb, 2))
1943                         ppp_receive_nonmp_frame(ppp, skb);
1944                 else {
1945                         ++ppp->dev->stats.rx_length_errors;
1946                         kfree_skb(skb);
1947                         ppp_receive_error(ppp);
1948                 }
1949         }
1950
1951         return;
1952
1953  err:
1954         kfree_skb(skb);
1955         ppp_receive_error(ppp);
1956 }
1957
1958 /*
1959  * Insert a fragment on the MP reconstruction queue.
1960  * The queue is ordered by increasing sequence number.
1961  */
1962 static void
1963 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1964 {
1965         struct sk_buff *p;
1966         struct sk_buff_head *list = &ppp->mrq;
1967         u32 seq = skb->sequence;
1968
1969         /* N.B. we don't need to lock the list lock because we have the
1970            ppp unit receive-side lock. */
1971         skb_queue_walk(list, p) {
1972                 if (seq_before(seq, p->sequence))
1973                         break;
1974         }
1975         __skb_queue_before(list, p, skb);
1976 }
1977
1978 /*
1979  * Reconstruct a packet from the MP fragment queue.
1980  * We go through increasing sequence numbers until we find a
1981  * complete packet, or we get to the sequence number for a fragment
1982  * which hasn't arrived but might still do so.
1983  */
1984 static struct sk_buff *
1985 ppp_mp_reconstruct(struct ppp *ppp)
1986 {
1987         u32 seq = ppp->nextseq;
1988         u32 minseq = ppp->minseq;
1989         struct sk_buff_head *list = &ppp->mrq;
1990         struct sk_buff *p, *next;
1991         struct sk_buff *head, *tail;
1992         struct sk_buff *skb = NULL;
1993         int lost = 0, len = 0;
1994
1995         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1996                 return NULL;
1997         head = list->next;
1998         tail = NULL;
1999         for (p = head; p != (struct sk_buff *) list; p = next) {
2000                 next = p->next;
2001                 if (seq_before(p->sequence, seq)) {
2002                         /* this can't happen, anyway ignore the skb */
2003                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
2004                                p->sequence, seq);
2005                         head = next;
2006                         continue;
2007                 }
2008                 if (p->sequence != seq) {
2009                         /* Fragment `seq' is missing.  If it is after
2010                            minseq, it might arrive later, so stop here. */
2011                         if (seq_after(seq, minseq))
2012                                 break;
2013                         /* Fragment `seq' is lost, keep going. */
2014                         lost = 1;
2015                         seq = seq_before(minseq, p->sequence)?
2016                                 minseq + 1: p->sequence;
2017                         next = p;
2018                         continue;
2019                 }
2020
2021                 /*
2022                  * At this point we know that all the fragments from
2023                  * ppp->nextseq to seq are either present or lost.
2024                  * Also, there are no complete packets in the queue
2025                  * that have no missing fragments and end before this
2026                  * fragment.
2027                  */
2028
2029                 /* B bit set indicates this fragment starts a packet */
2030                 if (p->BEbits & B) {
2031                         head = p;
2032                         lost = 0;
2033                         len = 0;
2034                 }
2035
2036                 len += p->len;
2037
2038                 /* Got a complete packet yet? */
2039                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
2040                         if (len > ppp->mrru + 2) {
2041                                 ++ppp->dev->stats.rx_length_errors;
2042                                 printk(KERN_DEBUG "PPP: reconstructed packet"
2043                                        " is too long (%d)\n", len);
2044                         } else if (p == head) {
2045                                 /* fragment is complete packet - reuse skb */
2046                                 tail = p;
2047                                 skb = skb_get(p);
2048                                 break;
2049                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
2050                                 ++ppp->dev->stats.rx_missed_errors;
2051                                 printk(KERN_DEBUG "PPP: no memory for "
2052                                        "reconstructed packet");
2053                         } else {
2054                                 tail = p;
2055                                 break;
2056                         }
2057                         ppp->nextseq = seq + 1;
2058                 }
2059
2060                 /*
2061                  * If this is the ending fragment of a packet,
2062                  * and we haven't found a complete valid packet yet,
2063                  * we can discard up to and including this fragment.
2064                  */
2065                 if (p->BEbits & E)
2066                         head = next;
2067
2068                 ++seq;
2069         }
2070
2071         /* If we have a complete packet, copy it all into one skb. */
2072         if (tail != NULL) {
2073                 /* If we have discarded any fragments,
2074                    signal a receive error. */
2075                 if (head->sequence != ppp->nextseq) {
2076                         if (ppp->debug & 1)
2077                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
2078                                        ppp->nextseq, head->sequence-1);
2079                         ++ppp->dev->stats.rx_dropped;
2080                         ppp_receive_error(ppp);
2081                 }
2082
2083                 if (head != tail)
2084                         /* copy to a single skb */
2085                         for (p = head; p != tail->next; p = p->next)
2086                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
2087                 ppp->nextseq = tail->sequence + 1;
2088                 head = tail->next;
2089         }
2090
2091         /* Discard all the skbuffs that we have copied the data out of
2092            or that we can't use. */
2093         while ((p = list->next) != head) {
2094                 __skb_unlink(p, list);
2095                 kfree_skb(p);
2096         }
2097
2098         return skb;
2099 }
2100 #endif /* CONFIG_PPP_MULTILINK */
2101
2102 /*
2103  * Channel interface.
2104  */
2105
2106 /* Create a new, unattached ppp channel. */
2107 int ppp_register_channel(struct ppp_channel *chan)
2108 {
2109         return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2110 }
2111
2112 /* Create a new, unattached ppp channel for specified net. */
2113 int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2114 {
2115         struct channel *pch;
2116         struct ppp_net *pn;
2117
2118         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2119         if (!pch)
2120                 return -ENOMEM;
2121
2122         pn = ppp_pernet(net);
2123
2124         pch->ppp = NULL;
2125         pch->chan = chan;
2126         pch->chan_net = net;
2127         chan->ppp = pch;
2128         init_ppp_file(&pch->file, CHANNEL);
2129         pch->file.hdrlen = chan->hdrlen;
2130 #ifdef CONFIG_PPP_MULTILINK
2131         pch->lastseq = -1;
2132 #endif /* CONFIG_PPP_MULTILINK */
2133         init_rwsem(&pch->chan_sem);
2134         spin_lock_init(&pch->downl);
2135         rwlock_init(&pch->upl);
2136
2137         spin_lock_bh(&pn->all_channels_lock);
2138         pch->file.index = ++pn->last_channel_index;
2139         list_add(&pch->list, &pn->new_channels);
2140         atomic_inc(&channel_count);
2141         spin_unlock_bh(&pn->all_channels_lock);
2142
2143         return 0;
2144 }
2145
2146 /*
2147  * Return the index of a channel.
2148  */
2149 int ppp_channel_index(struct ppp_channel *chan)
2150 {
2151         struct channel *pch = chan->ppp;
2152
2153         if (pch)
2154                 return pch->file.index;
2155         return -1;
2156 }
2157
2158 /*
2159  * Return the PPP unit number to which a channel is connected.
2160  */
2161 int ppp_unit_number(struct ppp_channel *chan)
2162 {
2163         struct channel *pch = chan->ppp;
2164         int unit = -1;
2165
2166         if (pch) {
2167                 read_lock_bh(&pch->upl);
2168                 if (pch->ppp)
2169                         unit = pch->ppp->file.index;
2170                 read_unlock_bh(&pch->upl);
2171         }
2172         return unit;
2173 }
2174
2175 /*
2176  * Return the PPP device interface name of a channel.
2177  */
2178 char *ppp_dev_name(struct ppp_channel *chan)
2179 {
2180         struct channel *pch = chan->ppp;
2181         char *name = NULL;
2182
2183         if (pch) {
2184                 read_lock_bh(&pch->upl);
2185                 if (pch->ppp && pch->ppp->dev)
2186                         name = pch->ppp->dev->name;
2187                 read_unlock_bh(&pch->upl);
2188         }
2189         return name;
2190 }
2191
2192
2193 /*
2194  * Disconnect a channel from the generic layer.
2195  * This must be called in process context.
2196  */
2197 void
2198 ppp_unregister_channel(struct ppp_channel *chan)
2199 {
2200         struct channel *pch = chan->ppp;
2201         struct ppp_net *pn;
2202
2203         if (!pch)
2204                 return;         /* should never happen */
2205
2206         chan->ppp = NULL;
2207
2208         /*
2209          * This ensures that we have returned from any calls into the
2210          * the channel's start_xmit or ioctl routine before we proceed.
2211          */
2212         down_write(&pch->chan_sem);
2213         spin_lock_bh(&pch->downl);
2214         pch->chan = NULL;
2215         spin_unlock_bh(&pch->downl);
2216         up_write(&pch->chan_sem);
2217         ppp_disconnect_channel(pch);
2218
2219         pn = ppp_pernet(pch->chan_net);
2220         spin_lock_bh(&pn->all_channels_lock);
2221         list_del(&pch->list);
2222         spin_unlock_bh(&pn->all_channels_lock);
2223
2224         pch->file.dead = 1;
2225         wake_up_interruptible(&pch->file.rwait);
2226         if (atomic_dec_and_test(&pch->file.refcnt))
2227                 ppp_destroy_channel(pch);
2228 }
2229
2230 /*
2231  * Callback from a channel when it can accept more to transmit.
2232  * This should be called at BH/softirq level, not interrupt level.
2233  */
2234 void
2235 ppp_output_wakeup(struct ppp_channel *chan)
2236 {
2237         struct channel *pch = chan->ppp;
2238
2239         if (!pch)
2240                 return;
2241         ppp_channel_push(pch);
2242 }
2243
2244 /*
2245  * Compression control.
2246  */
2247
2248 /* Process the PPPIOCSCOMPRESS ioctl. */
2249 static int
2250 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2251 {
2252         int err;
2253         struct compressor *cp, *ocomp;
2254         struct ppp_option_data data;
2255         void *state, *ostate;
2256         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2257
2258         err = -EFAULT;
2259         if (copy_from_user(&data, (void __user *) arg, sizeof(data)) ||
2260             (data.length <= CCP_MAX_OPTION_LENGTH &&
2261              copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2262                 goto out;
2263         err = -EINVAL;
2264         if (data.length > CCP_MAX_OPTION_LENGTH ||
2265             ccp_option[1] < 2 || ccp_option[1] > data.length)
2266                 goto out;
2267
2268         cp = try_then_request_module(
2269                 find_compressor(ccp_option[0]),
2270                 "ppp-compress-%d", ccp_option[0]);
2271         if (!cp)
2272                 goto out;
2273
2274         err = -ENOBUFS;
2275         if (data.transmit) {
2276                 state = cp->comp_alloc(ccp_option, data.length);
2277                 if (state) {
2278                         ppp_xmit_lock(ppp);
2279                         ppp->xstate &= ~SC_COMP_RUN;
2280                         ocomp = ppp->xcomp;
2281                         ostate = ppp->xc_state;
2282                         ppp->xcomp = cp;
2283                         ppp->xc_state = state;
2284                         ppp_xmit_unlock(ppp);
2285                         if (ostate) {
2286                                 ocomp->comp_free(ostate);
2287                                 module_put(ocomp->owner);
2288                         }
2289                         err = 0;
2290                 } else
2291                         module_put(cp->owner);
2292
2293         } else {
2294                 state = cp->decomp_alloc(ccp_option, data.length);
2295                 if (state) {
2296                         ppp_recv_lock(ppp);
2297                         ppp->rstate &= ~SC_DECOMP_RUN;
2298                         ocomp = ppp->rcomp;
2299                         ostate = ppp->rc_state;
2300                         ppp->rcomp = cp;
2301                         ppp->rc_state = state;
2302                         ppp_recv_unlock(ppp);
2303                         if (ostate) {
2304                                 ocomp->decomp_free(ostate);
2305                                 module_put(ocomp->owner);
2306                         }
2307                         err = 0;
2308                 } else
2309                         module_put(cp->owner);
2310         }
2311
2312  out:
2313         return err;
2314 }
2315
2316 /*
2317  * Look at a CCP packet and update our state accordingly.
2318  * We assume the caller has the xmit or recv path locked.
2319  */
2320 static void
2321 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2322 {
2323         unsigned char *dp;
2324         int len;
2325
2326         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2327                 return; /* no header */
2328         dp = skb->data + 2;
2329
2330         switch (CCP_CODE(dp)) {
2331         case CCP_CONFREQ:
2332
2333                 /* A ConfReq starts negotiation of compression
2334                  * in one direction of transmission,
2335                  * and hence brings it down...but which way?
2336                  *
2337                  * Remember:
2338                  * A ConfReq indicates what the sender would like to receive
2339                  */
2340                 if(inbound)
2341                         /* He is proposing what I should send */
2342                         ppp->xstate &= ~SC_COMP_RUN;
2343                 else
2344                         /* I am proposing to what he should send */
2345                         ppp->rstate &= ~SC_DECOMP_RUN;
2346
2347                 break;
2348
2349         case CCP_TERMREQ:
2350         case CCP_TERMACK:
2351                 /*
2352                  * CCP is going down, both directions of transmission
2353                  */
2354                 ppp->rstate &= ~SC_DECOMP_RUN;
2355                 ppp->xstate &= ~SC_COMP_RUN;
2356                 break;
2357
2358         case CCP_CONFACK:
2359                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2360                         break;
2361                 len = CCP_LENGTH(dp);
2362                 if (!pskb_may_pull(skb, len + 2))
2363                         return;         /* too short */
2364                 dp += CCP_HDRLEN;
2365                 len -= CCP_HDRLEN;
2366                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2367                         break;
2368                 if (inbound) {
2369                         /* we will start receiving compressed packets */
2370                         if (!ppp->rc_state)
2371                                 break;
2372                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2373                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2374                                 ppp->rstate |= SC_DECOMP_RUN;
2375                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2376                         }
2377                 } else {
2378                         /* we will soon start sending compressed packets */
2379                         if (!ppp->xc_state)
2380                                 break;
2381                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2382                                         ppp->file.index, 0, ppp->debug))
2383                                 ppp->xstate |= SC_COMP_RUN;
2384                 }
2385                 break;
2386
2387         case CCP_RESETACK:
2388                 /* reset the [de]compressor */
2389                 if ((ppp->flags & SC_CCP_UP) == 0)
2390                         break;
2391                 if (inbound) {
2392                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2393                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2394                                 ppp->rstate &= ~SC_DC_ERROR;
2395                         }
2396                 } else {
2397                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2398                                 ppp->xcomp->comp_reset(ppp->xc_state);
2399                 }
2400                 break;
2401         }
2402 }
2403
2404 /* Free up compression resources. */
2405 static void
2406 ppp_ccp_closed(struct ppp *ppp)
2407 {
2408         void *xstate, *rstate;
2409         struct compressor *xcomp, *rcomp;
2410
2411         ppp_lock(ppp);
2412         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2413         ppp->xstate = 0;
2414         xcomp = ppp->xcomp;
2415         xstate = ppp->xc_state;
2416         ppp->xc_state = NULL;
2417         ppp->rstate = 0;
2418         rcomp = ppp->rcomp;
2419         rstate = ppp->rc_state;
2420         ppp->rc_state = NULL;
2421         ppp_unlock(ppp);
2422
2423         if (xstate) {
2424                 xcomp->comp_free(xstate);
2425                 module_put(xcomp->owner);
2426         }
2427         if (rstate) {
2428                 rcomp->decomp_free(rstate);
2429                 module_put(rcomp->owner);
2430         }
2431 }
2432
2433 /* List of compressors. */
2434 static LIST_HEAD(compressor_list);
2435 static DEFINE_SPINLOCK(compressor_list_lock);
2436
2437 struct compressor_entry {
2438         struct list_head list;
2439         struct compressor *comp;
2440 };
2441
2442 static struct compressor_entry *
2443 find_comp_entry(int proto)
2444 {
2445         struct compressor_entry *ce;
2446
2447         list_for_each_entry(ce, &compressor_list, list) {
2448                 if (ce->comp->compress_proto == proto)
2449                         return ce;
2450         }
2451         return NULL;
2452 }
2453
2454 /* Register a compressor */
2455 int
2456 ppp_register_compressor(struct compressor *cp)
2457 {
2458         struct compressor_entry *ce;
2459         int ret;
2460         spin_lock(&compressor_list_lock);
2461         ret = -EEXIST;
2462         if (find_comp_entry(cp->compress_proto))
2463                 goto out;
2464         ret = -ENOMEM;
2465         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2466         if (!ce)
2467                 goto out;
2468         ret = 0;
2469         ce->comp = cp;
2470         list_add(&ce->list, &compressor_list);
2471  out:
2472         spin_unlock(&compressor_list_lock);
2473         return ret;
2474 }
2475
2476 /* Unregister a compressor */
2477 void
2478 ppp_unregister_compressor(struct compressor *cp)
2479 {
2480         struct compressor_entry *ce;
2481
2482         spin_lock(&compressor_list_lock);
2483         ce = find_comp_entry(cp->compress_proto);
2484         if (ce && ce->comp == cp) {
2485                 list_del(&ce->list);
2486                 kfree(ce);
2487         }
2488         spin_unlock(&compressor_list_lock);
2489 }
2490
2491 /* Find a compressor. */
2492 static struct compressor *
2493 find_compressor(int type)
2494 {
2495         struct compressor_entry *ce;
2496         struct compressor *cp = NULL;
2497
2498         spin_lock(&compressor_list_lock);
2499         ce = find_comp_entry(type);
2500         if (ce) {
2501                 cp = ce->comp;
2502                 if (!try_module_get(cp->owner))
2503                         cp = NULL;
2504         }
2505         spin_unlock(&compressor_list_lock);
2506         return cp;
2507 }
2508
2509 /*
2510  * Miscelleneous stuff.
2511  */
2512
2513 static void
2514 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2515 {
2516         struct slcompress *vj = ppp->vj;
2517
2518         memset(st, 0, sizeof(*st));
2519         st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
2520         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2521         st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
2522         st->p.ppp_opackets = ppp->dev->stats.tx_packets;
2523         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2524         st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
2525         if (!vj)
2526                 return;
2527         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2528         st->vj.vjs_compressed = vj->sls_o_compressed;
2529         st->vj.vjs_searches = vj->sls_o_searches;
2530         st->vj.vjs_misses = vj->sls_o_misses;
2531         st->vj.vjs_errorin = vj->sls_i_error;
2532         st->vj.vjs_tossed = vj->sls_i_tossed;
2533         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2534         st->vj.vjs_compressedin = vj->sls_i_compressed;
2535 }
2536
2537 /*
2538  * Stuff for handling the lists of ppp units and channels
2539  * and for initialization.
2540  */
2541
2542 /*
2543  * Create a new ppp interface unit.  Fails if it can't allocate memory
2544  * or if there is already a unit with the requested number.
2545  * unit == -1 means allocate a new number.
2546  */
2547 static struct ppp *
2548 ppp_create_interface(struct net *net, int unit, int *retp)
2549 {
2550         struct ppp *ppp;
2551         struct ppp_net *pn;
2552         struct net_device *dev = NULL;
2553         int ret = -ENOMEM;
2554         int i;
2555
2556         dev = alloc_netdev(sizeof(struct ppp), "", ppp_setup);
2557         if (!dev)
2558                 goto out1;
2559
2560         pn = ppp_pernet(net);
2561
2562         ppp = netdev_priv(dev);
2563         ppp->dev = dev;
2564         ppp->mru = PPP_MRU;
2565         init_ppp_file(&ppp->file, INTERFACE);
2566         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2567         for (i = 0; i < NUM_NP; ++i)
2568                 ppp->npmode[i] = NPMODE_PASS;
2569         INIT_LIST_HEAD(&ppp->channels);
2570         spin_lock_init(&ppp->rlock);
2571         spin_lock_init(&ppp->wlock);
2572 #ifdef CONFIG_PPP_MULTILINK
2573         ppp->minseq = -1;
2574         skb_queue_head_init(&ppp->mrq);
2575 #endif /* CONFIG_PPP_MULTILINK */
2576
2577         /*
2578          * drum roll: don't forget to set
2579          * the net device is belong to
2580          */
2581         dev_net_set(dev, net);
2582
2583         ret = -EEXIST;
2584         mutex_lock(&pn->all_ppp_mutex);
2585
2586         if (unit < 0) {
2587                 unit = unit_get(&pn->units_idr, ppp);
2588                 if (unit < 0) {
2589                         *retp = unit;
2590                         goto out2;
2591                 }
2592         } else {
2593                 if (unit_find(&pn->units_idr, unit))
2594                         goto out2; /* unit already exists */
2595                 /*
2596                  * if caller need a specified unit number
2597                  * lets try to satisfy him, otherwise --
2598                  * he should better ask us for new unit number
2599                  *
2600                  * NOTE: yes I know that returning EEXIST it's not
2601                  * fair but at least pppd will ask us to allocate
2602                  * new unit in this case so user is happy :)
2603                  */
2604                 unit = unit_set(&pn->units_idr, ppp, unit);
2605                 if (unit < 0)
2606                         goto out2;
2607         }
2608
2609         /* Initialize the new ppp unit */
2610         ppp->file.index = unit;
2611         sprintf(dev->name, "ppp%d", unit);
2612
2613         ret = register_netdev(dev);
2614         if (ret != 0) {
2615                 unit_put(&pn->units_idr, unit);
2616                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2617                        dev->name, ret);
2618                 goto out2;
2619         }
2620
2621         ppp->ppp_net = net;
2622
2623         atomic_inc(&ppp_unit_count);
2624         mutex_unlock(&pn->all_ppp_mutex);
2625
2626         *retp = 0;
2627         return ppp;
2628
2629 out2:
2630         mutex_unlock(&pn->all_ppp_mutex);
2631         free_netdev(dev);
2632 out1:
2633         *retp = ret;
2634         return NULL;
2635 }
2636
2637 /*
2638  * Initialize a ppp_file structure.
2639  */
2640 static void
2641 init_ppp_file(struct ppp_file *pf, int kind)
2642 {
2643         pf->kind = kind;
2644         skb_queue_head_init(&pf->xq);
2645         skb_queue_head_init(&pf->rq);
2646         atomic_set(&pf->refcnt, 1);
2647         init_waitqueue_head(&pf->rwait);
2648 }
2649
2650 /*
2651  * Take down a ppp interface unit - called when the owning file
2652  * (the one that created the unit) is closed or detached.
2653  */
2654 static void ppp_shutdown_interface(struct ppp *ppp)
2655 {
2656         struct ppp_net *pn;
2657
2658         pn = ppp_pernet(ppp->ppp_net);
2659         mutex_lock(&pn->all_ppp_mutex);
2660
2661         /* This will call dev_close() for us. */
2662         ppp_lock(ppp);
2663         if (!ppp->closing) {
2664                 ppp->closing = 1;
2665                 ppp_unlock(ppp);
2666                 unregister_netdev(ppp->dev);
2667         } else
2668                 ppp_unlock(ppp);
2669
2670         unit_put(&pn->units_idr, ppp->file.index);
2671         ppp->file.dead = 1;
2672         ppp->owner = NULL;
2673         wake_up_interruptible(&ppp->file.rwait);
2674
2675         mutex_unlock(&pn->all_ppp_mutex);
2676 }
2677
2678 /*
2679  * Free the memory used by a ppp unit.  This is only called once
2680  * there are no channels connected to the unit and no file structs
2681  * that reference the unit.
2682  */
2683 static void ppp_destroy_interface(struct ppp *ppp)
2684 {
2685         atomic_dec(&ppp_unit_count);
2686
2687         if (!ppp->file.dead || ppp->n_channels) {
2688                 /* "can't happen" */
2689                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2690                        "n_channels=%d !\n", ppp, ppp->file.dead,
2691                        ppp->n_channels);
2692                 return;
2693         }
2694
2695         ppp_ccp_closed(ppp);
2696         if (ppp->vj) {
2697                 slhc_free(ppp->vj);
2698                 ppp->vj = NULL;
2699         }
2700         skb_queue_purge(&ppp->file.xq);
2701         skb_queue_purge(&ppp->file.rq);
2702 #ifdef CONFIG_PPP_MULTILINK
2703         skb_queue_purge(&ppp->mrq);
2704 #endif /* CONFIG_PPP_MULTILINK */
2705 #ifdef CONFIG_PPP_FILTER
2706         kfree(ppp->pass_filter);
2707         ppp->pass_filter = NULL;
2708         kfree(ppp->active_filter);
2709         ppp->active_filter = NULL;
2710 #endif /* CONFIG_PPP_FILTER */
2711
2712         kfree_skb(ppp->xmit_pending);
2713
2714         free_netdev(ppp->dev);
2715 }
2716
2717 /*
2718  * Locate an existing ppp unit.
2719  * The caller should have locked the all_ppp_mutex.
2720  */
2721 static struct ppp *
2722 ppp_find_unit(struct ppp_net *pn, int unit)
2723 {
2724         return unit_find(&pn->units_idr, unit);
2725 }
2726
2727 /*
2728  * Locate an existing ppp channel.
2729  * The caller should have locked the all_channels_lock.
2730  * First we look in the new_channels list, then in the
2731  * all_channels list.  If found in the new_channels list,
2732  * we move it to the all_channels list.  This is for speed
2733  * when we have a lot of channels in use.
2734  */
2735 static struct channel *
2736 ppp_find_channel(struct ppp_net *pn, int unit)
2737 {
2738         struct channel *pch;
2739
2740         list_for_each_entry(pch, &pn->new_channels, list) {
2741                 if (pch->file.index == unit) {
2742                         list_move(&pch->list, &pn->all_channels);
2743                         return pch;
2744                 }
2745         }
2746
2747         list_for_each_entry(pch, &pn->all_channels, list) {
2748                 if (pch->file.index == unit)
2749                         return pch;
2750         }
2751
2752         return NULL;
2753 }
2754
2755 /*
2756  * Connect a PPP channel to a PPP interface unit.
2757  */
2758 static int
2759 ppp_connect_channel(struct channel *pch, int unit)
2760 {
2761         struct ppp *ppp;
2762         struct ppp_net *pn;
2763         int ret = -ENXIO;
2764         int hdrlen;
2765
2766         pn = ppp_pernet(pch->chan_net);
2767
2768         mutex_lock(&pn->all_ppp_mutex);
2769         ppp = ppp_find_unit(pn, unit);
2770         if (!ppp)
2771                 goto out;
2772         write_lock_bh(&pch->upl);
2773         ret = -EINVAL;
2774         if (pch->ppp)
2775                 goto outl;
2776
2777         ppp_lock(ppp);
2778         if (pch->file.hdrlen > ppp->file.hdrlen)
2779                 ppp->file.hdrlen = pch->file.hdrlen;
2780         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2781         if (hdrlen > ppp->dev->hard_header_len)
2782                 ppp->dev->hard_header_len = hdrlen;
2783         list_add_tail(&pch->clist, &ppp->channels);
2784         ++ppp->n_channels;
2785         pch->ppp = ppp;
2786         atomic_inc(&ppp->file.refcnt);
2787         ppp_unlock(ppp);
2788         ret = 0;
2789
2790  outl:
2791         write_unlock_bh(&pch->upl);
2792  out:
2793         mutex_unlock(&pn->all_ppp_mutex);
2794         return ret;
2795 }
2796
2797 /*
2798  * Disconnect a channel from its ppp unit.
2799  */
2800 static int
2801 ppp_disconnect_channel(struct channel *pch)
2802 {
2803         struct ppp *ppp;
2804         int err = -EINVAL;
2805
2806         write_lock_bh(&pch->upl);
2807         ppp = pch->ppp;
2808         pch->ppp = NULL;
2809         write_unlock_bh(&pch->upl);
2810         if (ppp) {
2811                 /* remove it from the ppp unit's list */
2812                 ppp_lock(ppp);
2813                 list_del(&pch->clist);
2814                 if (--ppp->n_channels == 0)
2815                         wake_up_interruptible(&ppp->file.rwait);
2816                 ppp_unlock(ppp);
2817                 if (atomic_dec_and_test(&ppp->file.refcnt))
2818                         ppp_destroy_interface(ppp);
2819                 err = 0;
2820         }
2821         return err;
2822 }
2823
2824 /*
2825  * Free up the resources used by a ppp channel.
2826  */
2827 static void ppp_destroy_channel(struct channel *pch)
2828 {
2829         atomic_dec(&channel_count);
2830
2831         if (!pch->file.dead) {
2832                 /* "can't happen" */
2833                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2834                        pch);
2835                 return;
2836         }
2837         skb_queue_purge(&pch->file.xq);
2838         skb_queue_purge(&pch->file.rq);
2839         kfree(pch);
2840 }
2841
2842 static void __exit ppp_cleanup(void)
2843 {
2844         /* should never happen */
2845         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2846                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2847         unregister_chrdev(PPP_MAJOR, "ppp");
2848         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2849         class_destroy(ppp_class);
2850         unregister_pernet_device(&ppp_net_ops);
2851 }
2852
2853 /*
2854  * Units handling. Caller must protect concurrent access
2855  * by holding all_ppp_mutex
2856  */
2857
2858 /* associate pointer with specified number */
2859 static int unit_set(struct idr *p, void *ptr, int n)
2860 {
2861         int unit, err;
2862
2863 again:
2864         if (!idr_pre_get(p, GFP_KERNEL)) {
2865                 printk(KERN_ERR "PPP: No free memory for idr\n");
2866                 return -ENOMEM;
2867         }
2868
2869         err = idr_get_new_above(p, ptr, n, &unit);
2870         if (err == -EAGAIN)
2871                 goto again;
2872
2873         if (unit != n) {
2874                 idr_remove(p, unit);
2875                 return -EINVAL;
2876         }
2877
2878         return unit;
2879 }
2880
2881 /* get new free unit number and associate pointer with it */
2882 static int unit_get(struct idr *p, void *ptr)
2883 {
2884         int unit, err;
2885
2886 again:
2887         if (!idr_pre_get(p, GFP_KERNEL)) {
2888                 printk(KERN_ERR "PPP: No free memory for idr\n");
2889                 return -ENOMEM;
2890         }
2891
2892         err = idr_get_new_above(p, ptr, 0, &unit);
2893         if (err == -EAGAIN)
2894                 goto again;
2895
2896         return unit;
2897 }
2898
2899 /* put unit number back to a pool */
2900 static void unit_put(struct idr *p, int n)
2901 {
2902         idr_remove(p, n);
2903 }
2904
2905 /* get pointer associated with the number */
2906 static void *unit_find(struct idr *p, int n)
2907 {
2908         return idr_find(p, n);
2909 }
2910
2911 /* Module/initialization stuff */
2912
2913 module_init(ppp_init);
2914 module_exit(ppp_cleanup);
2915
2916 EXPORT_SYMBOL(ppp_register_net_channel);
2917 EXPORT_SYMBOL(ppp_register_channel);
2918 EXPORT_SYMBOL(ppp_unregister_channel);
2919 EXPORT_SYMBOL(ppp_channel_index);
2920 EXPORT_SYMBOL(ppp_unit_number);
2921 EXPORT_SYMBOL(ppp_dev_name);
2922 EXPORT_SYMBOL(ppp_input);
2923 EXPORT_SYMBOL(ppp_input_error);
2924 EXPORT_SYMBOL(ppp_output_wakeup);
2925 EXPORT_SYMBOL(ppp_register_compressor);
2926 EXPORT_SYMBOL(ppp_unregister_compressor);
2927 MODULE_LICENSE("GPL");
2928 MODULE_ALIAS_CHARDEV(PPP_MAJOR, 0);
2929 MODULE_ALIAS("devname:ppp");