8518a2e58e5362254221ba11a0ba34146d84f47b
[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/smp_lock.h>
44 #include <linux/spinlock.h>
45 #include <linux/rwsem.h>
46 #include <linux/stddef.h>
47 #include <linux/device.h>
48 #include <linux/mutex.h>
49 #include <linux/slab.h>
50 #include <net/slhc_vj.h>
51 #include <asm/atomic.h>
52
53 #include <linux/nsproxy.h>
54 #include <net/net_namespace.h>
55 #include <net/netns/generic.h>
56
57 #define PPP_VERSION     "2.4.2"
58
59 /*
60  * Network protocols we support.
61  */
62 #define NP_IP   0               /* Internet Protocol V4 */
63 #define NP_IPV6 1               /* Internet Protocol V6 */
64 #define NP_IPX  2               /* IPX protocol */
65 #define NP_AT   3               /* Appletalk protocol */
66 #define NP_MPLS_UC 4            /* MPLS unicast */
67 #define NP_MPLS_MC 5            /* MPLS multicast */
68 #define NUM_NP  6               /* Number of NPs. */
69
70 #define MPHDRLEN        6       /* multilink protocol header length */
71 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
72 #define MIN_FRAG_SIZE   64
73
74 /*
75  * An instance of /dev/ppp can be associated with either a ppp
76  * interface unit or a ppp channel.  In both cases, file->private_data
77  * points to one of these.
78  */
79 struct ppp_file {
80         enum {
81                 INTERFACE=1, CHANNEL
82         }               kind;
83         struct sk_buff_head xq;         /* pppd transmit queue */
84         struct sk_buff_head rq;         /* receive queue for pppd */
85         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
86         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
87         int             hdrlen;         /* space to leave for headers */
88         int             index;          /* interface unit / channel number */
89         int             dead;           /* unit/channel has been shut down */
90 };
91
92 #define PF_TO_X(pf, X)          container_of(pf, X, file)
93
94 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
95 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
96
97 /*
98  * Data structure describing one ppp unit.
99  * A ppp unit corresponds to a ppp network interface device
100  * and represents a multilink bundle.
101  * It can have 0 or more ppp channels connected to it.
102  */
103 struct ppp {
104         struct ppp_file file;           /* stuff for read/write/poll 0 */
105         struct file     *owner;         /* file that owns this unit 48 */
106         struct list_head channels;      /* list of attached channels 4c */
107         int             n_channels;     /* how many channels are attached 54 */
108         spinlock_t      rlock;          /* lock for receive side 58 */
109         spinlock_t      wlock;          /* lock for transmit side 5c */
110         int             mru;            /* max receive unit 60 */
111         unsigned int    flags;          /* control bits 64 */
112         unsigned int    xstate;         /* transmit state bits 68 */
113         unsigned int    rstate;         /* receive state bits 6c */
114         int             debug;          /* debug flags 70 */
115         struct slcompress *vj;          /* state for VJ header compression */
116         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
117         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
118         struct compressor *xcomp;       /* transmit packet compressor 8c */
119         void            *xc_state;      /* its internal state 90 */
120         struct compressor *rcomp;       /* receive decompressor 94 */
121         void            *rc_state;      /* its internal state 98 */
122         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
123         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
124         struct net_device *dev;         /* network interface device a4 */
125         int             closing;        /* is device closing down? a8 */
126 #ifdef CONFIG_PPP_MULTILINK
127         int             nxchan;         /* next channel to send something on */
128         u32             nxseq;          /* next sequence number to send */
129         int             mrru;           /* MP: max reconst. receive unit */
130         u32             nextseq;        /* MP: seq no of next packet */
131         u32             minseq;         /* MP: min of most recent seqnos */
132         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
133 #endif /* CONFIG_PPP_MULTILINK */
134 #ifdef CONFIG_PPP_FILTER
135         struct sock_filter *pass_filter;        /* filter for packets to pass */
136         struct sock_filter *active_filter;/* filter for pkts to reset idle */
137         unsigned pass_len, active_len;
138 #endif /* CONFIG_PPP_FILTER */
139         struct net      *ppp_net;       /* the net we belong to */
140 };
141
142 /*
143  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
144  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
145  * SC_MUST_COMP
146  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
147  * Bits in xstate: SC_COMP_RUN
148  */
149 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
150                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
151                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
152
153 /*
154  * Private data structure for each channel.
155  * This includes the data structure used for multilink.
156  */
157 struct channel {
158         struct ppp_file file;           /* stuff for read/write/poll */
159         struct list_head list;          /* link in all/new_channels list */
160         struct ppp_channel *chan;       /* public channel data structure */
161         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
162         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
163         struct ppp      *ppp;           /* ppp unit we're connected to */
164         struct net      *chan_net;      /* the net channel belongs to */
165         struct list_head clist;         /* link in list of channels per unit */
166         rwlock_t        upl;            /* protects `ppp' */
167 #ifdef CONFIG_PPP_MULTILINK
168         u8              avail;          /* flag used in multilink stuff */
169         u8              had_frag;       /* >= 1 fragments have been sent */
170         u32             lastseq;        /* MP: last sequence # received */
171         int             speed;          /* speed of the corresponding ppp channel*/
172 #endif /* CONFIG_PPP_MULTILINK */
173 };
174
175 /*
176  * SMP locking issues:
177  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
178  * list and the ppp.n_channels field, you need to take both locks
179  * before you modify them.
180  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
181  * channel.downl.
182  */
183
184 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
185 static atomic_t channel_count = ATOMIC_INIT(0);
186
187 /* per-net private data for this module */
188 static int ppp_net_id __read_mostly;
189 struct ppp_net {
190         /* units to ppp mapping */
191         struct idr units_idr;
192
193         /*
194          * all_ppp_mutex protects the units_idr mapping.
195          * It also ensures that finding a ppp unit in the units_idr
196          * map and updating its file.refcnt field is atomic.
197          */
198         struct mutex all_ppp_mutex;
199
200         /* channels */
201         struct list_head all_channels;
202         struct list_head new_channels;
203         int last_channel_index;
204
205         /*
206          * all_channels_lock protects all_channels and
207          * last_channel_index, and the atomicity of find
208          * a channel and updating its file.refcnt field.
209          */
210         spinlock_t all_channels_lock;
211 };
212
213 /* Get the PPP protocol number from a skb */
214 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
215
216 /* We limit the length of ppp->file.rq to this (arbitrary) value */
217 #define PPP_MAX_RQLEN   32
218
219 /*
220  * Maximum number of multilink fragments queued up.
221  * This has to be large enough to cope with the maximum latency of
222  * the slowest channel relative to the others.  Strictly it should
223  * depend on the number of channels and their characteristics.
224  */
225 #define PPP_MP_MAX_QLEN 128
226
227 /* Multilink header bits. */
228 #define B       0x80            /* this fragment begins a packet */
229 #define E       0x40            /* this fragment ends a packet */
230
231 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
232 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
233 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
234
235 /* Prototypes. */
236 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
237                         struct file *file, unsigned int cmd, unsigned long arg);
238 static void ppp_xmit_process(struct ppp *ppp);
239 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
240 static void ppp_push(struct ppp *ppp);
241 static void ppp_channel_push(struct channel *pch);
242 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
243                               struct channel *pch);
244 static void ppp_receive_error(struct ppp *ppp);
245 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
246 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
247                                             struct sk_buff *skb);
248 #ifdef CONFIG_PPP_MULTILINK
249 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
250                                 struct channel *pch);
251 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
252 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
253 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
254 #endif /* CONFIG_PPP_MULTILINK */
255 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
256 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
257 static void ppp_ccp_closed(struct ppp *ppp);
258 static struct compressor *find_compressor(int type);
259 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
260 static struct ppp *ppp_create_interface(struct net *net, int unit, int *retp);
261 static void init_ppp_file(struct ppp_file *pf, int kind);
262 static void ppp_shutdown_interface(struct ppp *ppp);
263 static void ppp_destroy_interface(struct ppp *ppp);
264 static struct ppp *ppp_find_unit(struct ppp_net *pn, int unit);
265 static struct channel *ppp_find_channel(struct ppp_net *pn, int unit);
266 static int ppp_connect_channel(struct channel *pch, int unit);
267 static int ppp_disconnect_channel(struct channel *pch);
268 static void ppp_destroy_channel(struct channel *pch);
269 static int unit_get(struct idr *p, void *ptr);
270 static int unit_set(struct idr *p, void *ptr, int n);
271 static void unit_put(struct idr *p, int n);
272 static void *unit_find(struct idr *p, int n);
273
274 static struct class *ppp_class;
275
276 /* per net-namespace data */
277 static inline struct ppp_net *ppp_pernet(struct net *net)
278 {
279         BUG_ON(!net);
280
281         return net_generic(net, ppp_net_id);
282 }
283
284 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
285 static inline int proto_to_npindex(int proto)
286 {
287         switch (proto) {
288         case PPP_IP:
289                 return NP_IP;
290         case PPP_IPV6:
291                 return NP_IPV6;
292         case PPP_IPX:
293                 return NP_IPX;
294         case PPP_AT:
295                 return NP_AT;
296         case PPP_MPLS_UC:
297                 return NP_MPLS_UC;
298         case PPP_MPLS_MC:
299                 return NP_MPLS_MC;
300         }
301         return -EINVAL;
302 }
303
304 /* Translates an NP index into a PPP protocol number */
305 static const int npindex_to_proto[NUM_NP] = {
306         PPP_IP,
307         PPP_IPV6,
308         PPP_IPX,
309         PPP_AT,
310         PPP_MPLS_UC,
311         PPP_MPLS_MC,
312 };
313
314 /* Translates an ethertype into an NP index */
315 static inline int ethertype_to_npindex(int ethertype)
316 {
317         switch (ethertype) {
318         case ETH_P_IP:
319                 return NP_IP;
320         case ETH_P_IPV6:
321                 return NP_IPV6;
322         case ETH_P_IPX:
323                 return NP_IPX;
324         case ETH_P_PPPTALK:
325         case ETH_P_ATALK:
326                 return NP_AT;
327         case ETH_P_MPLS_UC:
328                 return NP_MPLS_UC;
329         case ETH_P_MPLS_MC:
330                 return NP_MPLS_MC;
331         }
332         return -1;
333 }
334
335 /* Translates an NP index into an ethertype */
336 static const int npindex_to_ethertype[NUM_NP] = {
337         ETH_P_IP,
338         ETH_P_IPV6,
339         ETH_P_IPX,
340         ETH_P_PPPTALK,
341         ETH_P_MPLS_UC,
342         ETH_P_MPLS_MC,
343 };
344
345 /*
346  * Locking shorthand.
347  */
348 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
349 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
350 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
351 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
352 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
353                                      ppp_recv_lock(ppp); } while (0)
354 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
355                                      ppp_xmit_unlock(ppp); } while (0)
356
357 /*
358  * /dev/ppp device routines.
359  * The /dev/ppp device is used by pppd to control the ppp unit.
360  * It supports the read, write, ioctl and poll functions.
361  * Open instances of /dev/ppp can be in one of three states:
362  * unattached, attached to a ppp unit, or attached to a ppp channel.
363  */
364 static int ppp_open(struct inode *inode, struct file *file)
365 {
366         cycle_kernel_lock();
367         /*
368          * This could (should?) be enforced by the permissions on /dev/ppp.
369          */
370         if (!capable(CAP_NET_ADMIN))
371                 return -EPERM;
372         return 0;
373 }
374
375 static int ppp_release(struct inode *unused, struct file *file)
376 {
377         struct ppp_file *pf = file->private_data;
378         struct ppp *ppp;
379
380         if (pf) {
381                 file->private_data = NULL;
382                 if (pf->kind == INTERFACE) {
383                         ppp = PF_TO_PPP(pf);
384                         if (file == ppp->owner)
385                                 ppp_shutdown_interface(ppp);
386                 }
387                 if (atomic_dec_and_test(&pf->refcnt)) {
388                         switch (pf->kind) {
389                         case INTERFACE:
390                                 ppp_destroy_interface(PF_TO_PPP(pf));
391                                 break;
392                         case CHANNEL:
393                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
394                                 break;
395                         }
396                 }
397         }
398         return 0;
399 }
400
401 static ssize_t ppp_read(struct file *file, char __user *buf,
402                         size_t count, loff_t *ppos)
403 {
404         struct ppp_file *pf = file->private_data;
405         DECLARE_WAITQUEUE(wait, current);
406         ssize_t ret;
407         struct sk_buff *skb = NULL;
408         struct iovec iov;
409
410         ret = count;
411
412         if (!pf)
413                 return -ENXIO;
414         add_wait_queue(&pf->rwait, &wait);
415         for (;;) {
416                 set_current_state(TASK_INTERRUPTIBLE);
417                 skb = skb_dequeue(&pf->rq);
418                 if (skb)
419                         break;
420                 ret = 0;
421                 if (pf->dead)
422                         break;
423                 if (pf->kind == INTERFACE) {
424                         /*
425                          * Return 0 (EOF) on an interface that has no
426                          * channels connected, unless it is looping
427                          * network traffic (demand mode).
428                          */
429                         struct ppp *ppp = PF_TO_PPP(pf);
430                         if (ppp->n_channels == 0 &&
431                             (ppp->flags & SC_LOOP_TRAFFIC) == 0)
432                                 break;
433                 }
434                 ret = -EAGAIN;
435                 if (file->f_flags & O_NONBLOCK)
436                         break;
437                 ret = -ERESTARTSYS;
438                 if (signal_pending(current))
439                         break;
440                 schedule();
441         }
442         set_current_state(TASK_RUNNING);
443         remove_wait_queue(&pf->rwait, &wait);
444
445         if (!skb)
446                 goto out;
447
448         ret = -EOVERFLOW;
449         if (skb->len > count)
450                 goto outf;
451         ret = -EFAULT;
452         iov.iov_base = buf;
453         iov.iov_len = count;
454         if (skb_copy_datagram_iovec(skb, 0, &iov, skb->len))
455                 goto outf;
456         ret = skb->len;
457
458  outf:
459         kfree_skb(skb);
460  out:
461         return ret;
462 }
463
464 static ssize_t ppp_write(struct file *file, const char __user *buf,
465                          size_t count, loff_t *ppos)
466 {
467         struct ppp_file *pf = file->private_data;
468         struct sk_buff *skb;
469         ssize_t ret;
470
471         if (!pf)
472                 return -ENXIO;
473         ret = -ENOMEM;
474         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
475         if (!skb)
476                 goto out;
477         skb_reserve(skb, pf->hdrlen);
478         ret = -EFAULT;
479         if (copy_from_user(skb_put(skb, count), buf, count)) {
480                 kfree_skb(skb);
481                 goto out;
482         }
483
484         skb_queue_tail(&pf->xq, skb);
485
486         switch (pf->kind) {
487         case INTERFACE:
488                 ppp_xmit_process(PF_TO_PPP(pf));
489                 break;
490         case CHANNEL:
491                 ppp_channel_push(PF_TO_CHANNEL(pf));
492                 break;
493         }
494
495         ret = count;
496
497  out:
498         return ret;
499 }
500
501 /* No kernel lock - fine */
502 static unsigned int ppp_poll(struct file *file, poll_table *wait)
503 {
504         struct ppp_file *pf = file->private_data;
505         unsigned int mask;
506
507         if (!pf)
508                 return 0;
509         poll_wait(file, &pf->rwait, wait);
510         mask = POLLOUT | POLLWRNORM;
511         if (skb_peek(&pf->rq))
512                 mask |= POLLIN | POLLRDNORM;
513         if (pf->dead)
514                 mask |= POLLHUP;
515         else if (pf->kind == INTERFACE) {
516                 /* see comment in ppp_read */
517                 struct ppp *ppp = PF_TO_PPP(pf);
518                 if (ppp->n_channels == 0 &&
519                     (ppp->flags & SC_LOOP_TRAFFIC) == 0)
520                         mask |= POLLIN | POLLRDNORM;
521         }
522
523         return mask;
524 }
525
526 #ifdef CONFIG_PPP_FILTER
527 static int get_filter(void __user *arg, struct sock_filter **p)
528 {
529         struct sock_fprog uprog;
530         struct sock_filter *code = NULL;
531         int len, err;
532
533         if (copy_from_user(&uprog, arg, sizeof(uprog)))
534                 return -EFAULT;
535
536         if (!uprog.len) {
537                 *p = NULL;
538                 return 0;
539         }
540
541         len = uprog.len * sizeof(struct sock_filter);
542         code = kmalloc(len, GFP_KERNEL);
543         if (code == NULL)
544                 return -ENOMEM;
545
546         if (copy_from_user(code, uprog.filter, len)) {
547                 kfree(code);
548                 return -EFAULT;
549         }
550
551         err = sk_chk_filter(code, uprog.len);
552         if (err) {
553                 kfree(code);
554                 return err;
555         }
556
557         *p = code;
558         return uprog.len;
559 }
560 #endif /* CONFIG_PPP_FILTER */
561
562 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
563 {
564         struct ppp_file *pf = file->private_data;
565         struct ppp *ppp;
566         int err = -EFAULT, val, val2, i;
567         struct ppp_idle idle;
568         struct npioctl npi;
569         int unit, cflags;
570         struct slcompress *vj;
571         void __user *argp = (void __user *)arg;
572         int __user *p = argp;
573
574         if (!pf)
575                 return ppp_unattached_ioctl(current->nsproxy->net_ns,
576                                         pf, file, cmd, arg);
577
578         if (cmd == PPPIOCDETACH) {
579                 /*
580                  * We have to be careful here... if the file descriptor
581                  * has been dup'd, we could have another process in the
582                  * middle of a poll using the same file *, so we had
583                  * better not free the interface data structures -
584                  * instead we fail the ioctl.  Even in this case, we
585                  * shut down the interface if we are the owner of it.
586                  * Actually, we should get rid of PPPIOCDETACH, userland
587                  * (i.e. pppd) could achieve the same effect by closing
588                  * this fd and reopening /dev/ppp.
589                  */
590                 err = -EINVAL;
591                 lock_kernel();
592                 if (pf->kind == INTERFACE) {
593                         ppp = PF_TO_PPP(pf);
594                         if (file == ppp->owner)
595                                 ppp_shutdown_interface(ppp);
596                 }
597                 if (atomic_long_read(&file->f_count) <= 2) {
598                         ppp_release(NULL, file);
599                         err = 0;
600                 } else
601                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
602                                atomic_long_read(&file->f_count));
603                 unlock_kernel();
604                 return err;
605         }
606
607         if (pf->kind == CHANNEL) {
608                 struct channel *pch;
609                 struct ppp_channel *chan;
610
611                 lock_kernel();
612                 pch = PF_TO_CHANNEL(pf);
613
614                 switch (cmd) {
615                 case PPPIOCCONNECT:
616                         if (get_user(unit, p))
617                                 break;
618                         err = ppp_connect_channel(pch, unit);
619                         break;
620
621                 case PPPIOCDISCONN:
622                         err = ppp_disconnect_channel(pch);
623                         break;
624
625                 default:
626                         down_read(&pch->chan_sem);
627                         chan = pch->chan;
628                         err = -ENOTTY;
629                         if (chan && chan->ops->ioctl)
630                                 err = chan->ops->ioctl(chan, cmd, arg);
631                         up_read(&pch->chan_sem);
632                 }
633                 unlock_kernel();
634                 return err;
635         }
636
637         if (pf->kind != INTERFACE) {
638                 /* can't happen */
639                 printk(KERN_ERR "PPP: not interface or channel??\n");
640                 return -EINVAL;
641         }
642
643         lock_kernel();
644         ppp = PF_TO_PPP(pf);
645         switch (cmd) {
646         case PPPIOCSMRU:
647                 if (get_user(val, p))
648                         break;
649                 ppp->mru = val;
650                 err = 0;
651                 break;
652
653         case PPPIOCSFLAGS:
654                 if (get_user(val, p))
655                         break;
656                 ppp_lock(ppp);
657                 cflags = ppp->flags & ~val;
658                 ppp->flags = val & SC_FLAG_BITS;
659                 ppp_unlock(ppp);
660                 if (cflags & SC_CCP_OPEN)
661                         ppp_ccp_closed(ppp);
662                 err = 0;
663                 break;
664
665         case PPPIOCGFLAGS:
666                 val = ppp->flags | ppp->xstate | ppp->rstate;
667                 if (put_user(val, p))
668                         break;
669                 err = 0;
670                 break;
671
672         case PPPIOCSCOMPRESS:
673                 err = ppp_set_compress(ppp, arg);
674                 break;
675
676         case PPPIOCGUNIT:
677                 if (put_user(ppp->file.index, p))
678                         break;
679                 err = 0;
680                 break;
681
682         case PPPIOCSDEBUG:
683                 if (get_user(val, p))
684                         break;
685                 ppp->debug = val;
686                 err = 0;
687                 break;
688
689         case PPPIOCGDEBUG:
690                 if (put_user(ppp->debug, p))
691                         break;
692                 err = 0;
693                 break;
694
695         case PPPIOCGIDLE:
696                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
697                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
698                 if (copy_to_user(argp, &idle, sizeof(idle)))
699                         break;
700                 err = 0;
701                 break;
702
703         case PPPIOCSMAXCID:
704                 if (get_user(val, p))
705                         break;
706                 val2 = 15;
707                 if ((val >> 16) != 0) {
708                         val2 = val >> 16;
709                         val &= 0xffff;
710                 }
711                 vj = slhc_init(val2+1, val+1);
712                 if (!vj) {
713                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
714                         err = -ENOMEM;
715                         break;
716                 }
717                 ppp_lock(ppp);
718                 if (ppp->vj)
719                         slhc_free(ppp->vj);
720                 ppp->vj = vj;
721                 ppp_unlock(ppp);
722                 err = 0;
723                 break;
724
725         case PPPIOCGNPMODE:
726         case PPPIOCSNPMODE:
727                 if (copy_from_user(&npi, argp, sizeof(npi)))
728                         break;
729                 err = proto_to_npindex(npi.protocol);
730                 if (err < 0)
731                         break;
732                 i = err;
733                 if (cmd == PPPIOCGNPMODE) {
734                         err = -EFAULT;
735                         npi.mode = ppp->npmode[i];
736                         if (copy_to_user(argp, &npi, sizeof(npi)))
737                                 break;
738                 } else {
739                         ppp->npmode[i] = npi.mode;
740                         /* we may be able to transmit more packets now (??) */
741                         netif_wake_queue(ppp->dev);
742                 }
743                 err = 0;
744                 break;
745
746 #ifdef CONFIG_PPP_FILTER
747         case PPPIOCSPASS:
748         {
749                 struct sock_filter *code;
750                 err = get_filter(argp, &code);
751                 if (err >= 0) {
752                         ppp_lock(ppp);
753                         kfree(ppp->pass_filter);
754                         ppp->pass_filter = code;
755                         ppp->pass_len = err;
756                         ppp_unlock(ppp);
757                         err = 0;
758                 }
759                 break;
760         }
761         case PPPIOCSACTIVE:
762         {
763                 struct sock_filter *code;
764                 err = get_filter(argp, &code);
765                 if (err >= 0) {
766                         ppp_lock(ppp);
767                         kfree(ppp->active_filter);
768                         ppp->active_filter = code;
769                         ppp->active_len = err;
770                         ppp_unlock(ppp);
771                         err = 0;
772                 }
773                 break;
774         }
775 #endif /* CONFIG_PPP_FILTER */
776
777 #ifdef CONFIG_PPP_MULTILINK
778         case PPPIOCSMRRU:
779                 if (get_user(val, p))
780                         break;
781                 ppp_recv_lock(ppp);
782                 ppp->mrru = val;
783                 ppp_recv_unlock(ppp);
784                 err = 0;
785                 break;
786 #endif /* CONFIG_PPP_MULTILINK */
787
788         default:
789                 err = -ENOTTY;
790         }
791         unlock_kernel();
792         return err;
793 }
794
795 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
796                         struct file *file, unsigned int cmd, unsigned long arg)
797 {
798         int unit, err = -EFAULT;
799         struct ppp *ppp;
800         struct channel *chan;
801         struct ppp_net *pn;
802         int __user *p = (int __user *)arg;
803
804         lock_kernel();
805         switch (cmd) {
806         case PPPIOCNEWUNIT:
807                 /* Create a new ppp unit */
808                 if (get_user(unit, p))
809                         break;
810                 ppp = ppp_create_interface(net, unit, &err);
811                 if (!ppp)
812                         break;
813                 file->private_data = &ppp->file;
814                 ppp->owner = file;
815                 err = -EFAULT;
816                 if (put_user(ppp->file.index, p))
817                         break;
818                 err = 0;
819                 break;
820
821         case PPPIOCATTACH:
822                 /* Attach to an existing ppp unit */
823                 if (get_user(unit, p))
824                         break;
825                 err = -ENXIO;
826                 pn = ppp_pernet(net);
827                 mutex_lock(&pn->all_ppp_mutex);
828                 ppp = ppp_find_unit(pn, unit);
829                 if (ppp) {
830                         atomic_inc(&ppp->file.refcnt);
831                         file->private_data = &ppp->file;
832                         err = 0;
833                 }
834                 mutex_unlock(&pn->all_ppp_mutex);
835                 break;
836
837         case PPPIOCATTCHAN:
838                 if (get_user(unit, p))
839                         break;
840                 err = -ENXIO;
841                 pn = ppp_pernet(net);
842                 spin_lock_bh(&pn->all_channels_lock);
843                 chan = ppp_find_channel(pn, unit);
844                 if (chan) {
845                         atomic_inc(&chan->file.refcnt);
846                         file->private_data = &chan->file;
847                         err = 0;
848                 }
849                 spin_unlock_bh(&pn->all_channels_lock);
850                 break;
851
852         default:
853                 err = -ENOTTY;
854         }
855         unlock_kernel();
856         return err;
857 }
858
859 static const struct file_operations ppp_device_fops = {
860         .owner          = THIS_MODULE,
861         .read           = ppp_read,
862         .write          = ppp_write,
863         .poll           = ppp_poll,
864         .unlocked_ioctl = ppp_ioctl,
865         .open           = ppp_open,
866         .release        = ppp_release
867 };
868
869 static __net_init int ppp_init_net(struct net *net)
870 {
871         struct ppp_net *pn = net_generic(net, ppp_net_id);
872
873         idr_init(&pn->units_idr);
874         mutex_init(&pn->all_ppp_mutex);
875
876         INIT_LIST_HEAD(&pn->all_channels);
877         INIT_LIST_HEAD(&pn->new_channels);
878
879         spin_lock_init(&pn->all_channels_lock);
880
881         return 0;
882 }
883
884 static __net_exit void ppp_exit_net(struct net *net)
885 {
886         struct ppp_net *pn = net_generic(net, ppp_net_id);
887
888         idr_destroy(&pn->units_idr);
889 }
890
891 static struct pernet_operations ppp_net_ops = {
892         .init = ppp_init_net,
893         .exit = ppp_exit_net,
894         .id   = &ppp_net_id,
895         .size = sizeof(struct ppp_net),
896 };
897
898 #define PPP_MAJOR       108
899
900 /* Called at boot time if ppp is compiled into the kernel,
901    or at module load time (from init_module) if compiled as a module. */
902 static int __init ppp_init(void)
903 {
904         int err;
905
906         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
907
908         err = register_pernet_device(&ppp_net_ops);
909         if (err) {
910                 printk(KERN_ERR "failed to register PPP pernet device (%d)\n", err);
911                 goto out;
912         }
913
914         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
915         if (err) {
916                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
917                 goto out_net;
918         }
919
920         ppp_class = class_create(THIS_MODULE, "ppp");
921         if (IS_ERR(ppp_class)) {
922                 err = PTR_ERR(ppp_class);
923                 goto out_chrdev;
924         }
925
926         /* not a big deal if we fail here :-) */
927         device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
928
929         return 0;
930
931 out_chrdev:
932         unregister_chrdev(PPP_MAJOR, "ppp");
933 out_net:
934         unregister_pernet_device(&ppp_net_ops);
935 out:
936         return err;
937 }
938
939 /*
940  * Network interface unit routines.
941  */
942 static netdev_tx_t
943 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
944 {
945         struct ppp *ppp = netdev_priv(dev);
946         int npi, proto;
947         unsigned char *pp;
948
949         npi = ethertype_to_npindex(ntohs(skb->protocol));
950         if (npi < 0)
951                 goto outf;
952
953         /* Drop, accept or reject the packet */
954         switch (ppp->npmode[npi]) {
955         case NPMODE_PASS:
956                 break;
957         case NPMODE_QUEUE:
958                 /* it would be nice to have a way to tell the network
959                    system to queue this one up for later. */
960                 goto outf;
961         case NPMODE_DROP:
962         case NPMODE_ERROR:
963                 goto outf;
964         }
965
966         /* Put the 2-byte PPP protocol number on the front,
967            making sure there is room for the address and control fields. */
968         if (skb_cow_head(skb, PPP_HDRLEN))
969                 goto outf;
970
971         pp = skb_push(skb, 2);
972         proto = npindex_to_proto[npi];
973         pp[0] = proto >> 8;
974         pp[1] = proto;
975
976         netif_stop_queue(dev);
977         skb_queue_tail(&ppp->file.xq, skb);
978         ppp_xmit_process(ppp);
979         return NETDEV_TX_OK;
980
981  outf:
982         kfree_skb(skb);
983         ++dev->stats.tx_dropped;
984         return NETDEV_TX_OK;
985 }
986
987 static int
988 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
989 {
990         struct ppp *ppp = netdev_priv(dev);
991         int err = -EFAULT;
992         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
993         struct ppp_stats stats;
994         struct ppp_comp_stats cstats;
995         char *vers;
996
997         switch (cmd) {
998         case SIOCGPPPSTATS:
999                 ppp_get_stats(ppp, &stats);
1000                 if (copy_to_user(addr, &stats, sizeof(stats)))
1001                         break;
1002                 err = 0;
1003                 break;
1004
1005         case SIOCGPPPCSTATS:
1006                 memset(&cstats, 0, sizeof(cstats));
1007                 if (ppp->xc_state)
1008                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
1009                 if (ppp->rc_state)
1010                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
1011                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
1012                         break;
1013                 err = 0;
1014                 break;
1015
1016         case SIOCGPPPVER:
1017                 vers = PPP_VERSION;
1018                 if (copy_to_user(addr, vers, strlen(vers) + 1))
1019                         break;
1020                 err = 0;
1021                 break;
1022
1023         default:
1024                 err = -EINVAL;
1025         }
1026
1027         return err;
1028 }
1029
1030 static const struct net_device_ops ppp_netdev_ops = {
1031         .ndo_start_xmit = ppp_start_xmit,
1032         .ndo_do_ioctl   = ppp_net_ioctl,
1033 };
1034
1035 static void ppp_setup(struct net_device *dev)
1036 {
1037         dev->netdev_ops = &ppp_netdev_ops;
1038         dev->hard_header_len = PPP_HDRLEN;
1039         dev->mtu = PPP_MTU;
1040         dev->addr_len = 0;
1041         dev->tx_queue_len = 3;
1042         dev->type = ARPHRD_PPP;
1043         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1044         dev->features |= NETIF_F_NETNS_LOCAL;
1045         dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
1046 }
1047
1048 /*
1049  * Transmit-side routines.
1050  */
1051
1052 /*
1053  * Called to do any work queued up on the transmit side
1054  * that can now be done.
1055  */
1056 static void
1057 ppp_xmit_process(struct ppp *ppp)
1058 {
1059         struct sk_buff *skb;
1060
1061         ppp_xmit_lock(ppp);
1062         if (!ppp->closing) {
1063                 ppp_push(ppp);
1064                 while (!ppp->xmit_pending &&
1065                        (skb = skb_dequeue(&ppp->file.xq)))
1066                         ppp_send_frame(ppp, skb);
1067                 /* If there's no work left to do, tell the core net
1068                    code that we can accept some more. */
1069                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1070                         netif_wake_queue(ppp->dev);
1071         }
1072         ppp_xmit_unlock(ppp);
1073 }
1074
1075 static inline struct sk_buff *
1076 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1077 {
1078         struct sk_buff *new_skb;
1079         int len;
1080         int new_skb_size = ppp->dev->mtu +
1081                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1082         int compressor_skb_size = ppp->dev->mtu +
1083                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1084         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1085         if (!new_skb) {
1086                 if (net_ratelimit())
1087                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1088                 return NULL;
1089         }
1090         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1091                 skb_reserve(new_skb,
1092                             ppp->dev->hard_header_len - PPP_HDRLEN);
1093
1094         /* compressor still expects A/C bytes in hdr */
1095         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1096                                    new_skb->data, skb->len + 2,
1097                                    compressor_skb_size);
1098         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1099                 kfree_skb(skb);
1100                 skb = new_skb;
1101                 skb_put(skb, len);
1102                 skb_pull(skb, 2);       /* pull off A/C bytes */
1103         } else if (len == 0) {
1104                 /* didn't compress, or CCP not up yet */
1105                 kfree_skb(new_skb);
1106                 new_skb = skb;
1107         } else {
1108                 /*
1109                  * (len < 0)
1110                  * MPPE requires that we do not send unencrypted
1111                  * frames.  The compressor will return -1 if we
1112                  * should drop the frame.  We cannot simply test
1113                  * the compress_proto because MPPE and MPPC share
1114                  * the same number.
1115                  */
1116                 if (net_ratelimit())
1117                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1118                 kfree_skb(skb);
1119                 kfree_skb(new_skb);
1120                 new_skb = NULL;
1121         }
1122         return new_skb;
1123 }
1124
1125 /*
1126  * Compress and send a frame.
1127  * The caller should have locked the xmit path,
1128  * and xmit_pending should be 0.
1129  */
1130 static void
1131 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1132 {
1133         int proto = PPP_PROTO(skb);
1134         struct sk_buff *new_skb;
1135         int len;
1136         unsigned char *cp;
1137
1138         if (proto < 0x8000) {
1139 #ifdef CONFIG_PPP_FILTER
1140                 /* check if we should pass this packet */
1141                 /* the filter instructions are constructed assuming
1142                    a four-byte PPP header on each packet */
1143                 *skb_push(skb, 2) = 1;
1144                 if (ppp->pass_filter &&
1145                     sk_run_filter(skb, ppp->pass_filter,
1146                                   ppp->pass_len) == 0) {
1147                         if (ppp->debug & 1)
1148                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1149                         kfree_skb(skb);
1150                         return;
1151                 }
1152                 /* if this packet passes the active filter, record the time */
1153                 if (!(ppp->active_filter &&
1154                       sk_run_filter(skb, ppp->active_filter,
1155                                     ppp->active_len) == 0))
1156                         ppp->last_xmit = jiffies;
1157                 skb_pull(skb, 2);
1158 #else
1159                 /* for data packets, record the time */
1160                 ppp->last_xmit = jiffies;
1161 #endif /* CONFIG_PPP_FILTER */
1162         }
1163
1164         ++ppp->dev->stats.tx_packets;
1165         ppp->dev->stats.tx_bytes += skb->len - 2;
1166
1167         switch (proto) {
1168         case PPP_IP:
1169                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1170                         break;
1171                 /* try to do VJ TCP header compression */
1172                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1173                                     GFP_ATOMIC);
1174                 if (!new_skb) {
1175                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1176                         goto drop;
1177                 }
1178                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1179                 cp = skb->data + 2;
1180                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1181                                     new_skb->data + 2, &cp,
1182                                     !(ppp->flags & SC_NO_TCP_CCID));
1183                 if (cp == skb->data + 2) {
1184                         /* didn't compress */
1185                         kfree_skb(new_skb);
1186                 } else {
1187                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1188                                 proto = PPP_VJC_COMP;
1189                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1190                         } else {
1191                                 proto = PPP_VJC_UNCOMP;
1192                                 cp[0] = skb->data[2];
1193                         }
1194                         kfree_skb(skb);
1195                         skb = new_skb;
1196                         cp = skb_put(skb, len + 2);
1197                         cp[0] = 0;
1198                         cp[1] = proto;
1199                 }
1200                 break;
1201
1202         case PPP_CCP:
1203                 /* peek at outbound CCP frames */
1204                 ppp_ccp_peek(ppp, skb, 0);
1205                 break;
1206         }
1207
1208         /* try to do packet compression */
1209         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state &&
1210             proto != PPP_LCP && proto != PPP_CCP) {
1211                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1212                         if (net_ratelimit())
1213                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1214                         goto drop;
1215                 }
1216                 skb = pad_compress_skb(ppp, skb);
1217                 if (!skb)
1218                         goto drop;
1219         }
1220
1221         /*
1222          * If we are waiting for traffic (demand dialling),
1223          * queue it up for pppd to receive.
1224          */
1225         if (ppp->flags & SC_LOOP_TRAFFIC) {
1226                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1227                         goto drop;
1228                 skb_queue_tail(&ppp->file.rq, skb);
1229                 wake_up_interruptible(&ppp->file.rwait);
1230                 return;
1231         }
1232
1233         ppp->xmit_pending = skb;
1234         ppp_push(ppp);
1235         return;
1236
1237  drop:
1238         kfree_skb(skb);
1239         ++ppp->dev->stats.tx_errors;
1240 }
1241
1242 /*
1243  * Try to send the frame in xmit_pending.
1244  * The caller should have the xmit path locked.
1245  */
1246 static void
1247 ppp_push(struct ppp *ppp)
1248 {
1249         struct list_head *list;
1250         struct channel *pch;
1251         struct sk_buff *skb = ppp->xmit_pending;
1252
1253         if (!skb)
1254                 return;
1255
1256         list = &ppp->channels;
1257         if (list_empty(list)) {
1258                 /* nowhere to send the packet, just drop it */
1259                 ppp->xmit_pending = NULL;
1260                 kfree_skb(skb);
1261                 return;
1262         }
1263
1264         if ((ppp->flags & SC_MULTILINK) == 0) {
1265                 /* not doing multilink: send it down the first channel */
1266                 list = list->next;
1267                 pch = list_entry(list, struct channel, clist);
1268
1269                 spin_lock_bh(&pch->downl);
1270                 if (pch->chan) {
1271                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1272                                 ppp->xmit_pending = NULL;
1273                 } else {
1274                         /* channel got unregistered */
1275                         kfree_skb(skb);
1276                         ppp->xmit_pending = NULL;
1277                 }
1278                 spin_unlock_bh(&pch->downl);
1279                 return;
1280         }
1281
1282 #ifdef CONFIG_PPP_MULTILINK
1283         /* Multilink: fragment the packet over as many links
1284            as can take the packet at the moment. */
1285         if (!ppp_mp_explode(ppp, skb))
1286                 return;
1287 #endif /* CONFIG_PPP_MULTILINK */
1288
1289         ppp->xmit_pending = NULL;
1290         kfree_skb(skb);
1291 }
1292
1293 #ifdef CONFIG_PPP_MULTILINK
1294 /*
1295  * Divide a packet to be transmitted into fragments and
1296  * send them out the individual links.
1297  */
1298 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1299 {
1300         int len, totlen;
1301         int i, bits, hdrlen, mtu;
1302         int flen;
1303         int navail, nfree, nzero;
1304         int nbigger;
1305         int totspeed;
1306         int totfree;
1307         unsigned char *p, *q;
1308         struct list_head *list;
1309         struct channel *pch;
1310         struct sk_buff *frag;
1311         struct ppp_channel *chan;
1312
1313         totspeed = 0; /*total bitrate of the bundle*/
1314         nfree = 0; /* # channels which have no packet already queued */
1315         navail = 0; /* total # of usable channels (not deregistered) */
1316         nzero = 0; /* number of channels with zero speed associated*/
1317         totfree = 0; /*total # of channels available and
1318                                   *having no queued packets before
1319                                   *starting the fragmentation*/
1320
1321         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1322         i = 0;
1323         list_for_each_entry(pch, &ppp->channels, clist) {
1324                 navail += pch->avail = (pch->chan != NULL);
1325                 pch->speed = pch->chan->speed;
1326                 if (pch->avail) {
1327                         if (skb_queue_empty(&pch->file.xq) ||
1328                                 !pch->had_frag) {
1329                                         if (pch->speed == 0)
1330                                                 nzero++;
1331                                         else
1332                                                 totspeed += pch->speed;
1333
1334                                         pch->avail = 2;
1335                                         ++nfree;
1336                                         ++totfree;
1337                                 }
1338                         if (!pch->had_frag && i < ppp->nxchan)
1339                                 ppp->nxchan = i;
1340                 }
1341                 ++i;
1342         }
1343         /*
1344          * Don't start sending this packet unless at least half of
1345          * the channels are free.  This gives much better TCP
1346          * performance if we have a lot of channels.
1347          */
1348         if (nfree == 0 || nfree < navail / 2)
1349                 return 0; /* can't take now, leave it in xmit_pending */
1350
1351         /* Do protocol field compression (XXX this should be optional) */
1352         p = skb->data;
1353         len = skb->len;
1354         if (*p == 0) {
1355                 ++p;
1356                 --len;
1357         }
1358
1359         totlen = len;
1360         nbigger = len % nfree;
1361
1362         /* skip to the channel after the one we last used
1363            and start at that one */
1364         list = &ppp->channels;
1365         for (i = 0; i < ppp->nxchan; ++i) {
1366                 list = list->next;
1367                 if (list == &ppp->channels) {
1368                         i = 0;
1369                         break;
1370                 }
1371         }
1372
1373         /* create a fragment for each channel */
1374         bits = B;
1375         while (len > 0) {
1376                 list = list->next;
1377                 if (list == &ppp->channels) {
1378                         i = 0;
1379                         continue;
1380                 }
1381                 pch = list_entry(list, struct channel, clist);
1382                 ++i;
1383                 if (!pch->avail)
1384                         continue;
1385
1386                 /*
1387                  * Skip this channel if it has a fragment pending already and
1388                  * we haven't given a fragment to all of the free channels.
1389                  */
1390                 if (pch->avail == 1) {
1391                         if (nfree > 0)
1392                                 continue;
1393                 } else {
1394                         pch->avail = 1;
1395                 }
1396
1397                 /* check the channel's mtu and whether it is still attached. */
1398                 spin_lock_bh(&pch->downl);
1399                 if (pch->chan == NULL) {
1400                         /* can't use this channel, it's being deregistered */
1401                         if (pch->speed == 0)
1402                                 nzero--;
1403                         else
1404                                 totspeed -= pch->speed;
1405
1406                         spin_unlock_bh(&pch->downl);
1407                         pch->avail = 0;
1408                         totlen = len;
1409                         totfree--;
1410                         nfree--;
1411                         if (--navail == 0)
1412                                 break;
1413                         continue;
1414                 }
1415
1416                 /*
1417                 *if the channel speed is not set divide
1418                 *the packet evenly among the free channels;
1419                 *otherwise divide it according to the speed
1420                 *of the channel we are going to transmit on
1421                 */
1422                 flen = len;
1423                 if (nfree > 0) {
1424                         if (pch->speed == 0) {
1425                                 flen = totlen/nfree;
1426                                 if (nbigger > 0) {
1427                                         flen++;
1428                                         nbigger--;
1429                                 }
1430                         } else {
1431                                 flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
1432                                         ((totspeed*totfree)/pch->speed)) - hdrlen;
1433                                 if (nbigger > 0) {
1434                                         flen += ((totfree - nzero)*pch->speed)/totspeed;
1435                                         nbigger -= ((totfree - nzero)*pch->speed)/
1436                                                         totspeed;
1437                                 }
1438                         }
1439                         nfree--;
1440                 }
1441
1442                 /*
1443                  *check if we are on the last channel or
1444                  *we exceded the lenght of the data to
1445                  *fragment
1446                  */
1447                 if ((nfree <= 0) || (flen > len))
1448                         flen = len;
1449                 /*
1450                  *it is not worth to tx on slow channels:
1451                  *in that case from the resulting flen according to the
1452                  *above formula will be equal or less than zero.
1453                  *Skip the channel in this case
1454                  */
1455                 if (flen <= 0) {
1456                         pch->avail = 2;
1457                         spin_unlock_bh(&pch->downl);
1458                         continue;
1459                 }
1460
1461                 mtu = pch->chan->mtu - hdrlen;
1462                 if (mtu < 4)
1463                         mtu = 4;
1464                 if (flen > mtu)
1465                         flen = mtu;
1466                 if (flen == len)
1467                         bits |= E;
1468                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1469                 if (!frag)
1470                         goto noskb;
1471                 q = skb_put(frag, flen + hdrlen);
1472
1473                 /* make the MP header */
1474                 q[0] = PPP_MP >> 8;
1475                 q[1] = PPP_MP;
1476                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1477                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1478                         q[3] = ppp->nxseq;
1479                 } else {
1480                         q[2] = bits;
1481                         q[3] = ppp->nxseq >> 16;
1482                         q[4] = ppp->nxseq >> 8;
1483                         q[5] = ppp->nxseq;
1484                 }
1485
1486                 memcpy(q + hdrlen, p, flen);
1487
1488                 /* try to send it down the channel */
1489                 chan = pch->chan;
1490                 if (!skb_queue_empty(&pch->file.xq) ||
1491                         !chan->ops->start_xmit(chan, frag))
1492                         skb_queue_tail(&pch->file.xq, frag);
1493                 pch->had_frag = 1;
1494                 p += flen;
1495                 len -= flen;
1496                 ++ppp->nxseq;
1497                 bits = 0;
1498                 spin_unlock_bh(&pch->downl);
1499         }
1500         ppp->nxchan = i;
1501
1502         return 1;
1503
1504  noskb:
1505         spin_unlock_bh(&pch->downl);
1506         if (ppp->debug & 1)
1507                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1508         ++ppp->dev->stats.tx_errors;
1509         ++ppp->nxseq;
1510         return 1;       /* abandon the frame */
1511 }
1512 #endif /* CONFIG_PPP_MULTILINK */
1513
1514 /*
1515  * Try to send data out on a channel.
1516  */
1517 static void
1518 ppp_channel_push(struct channel *pch)
1519 {
1520         struct sk_buff *skb;
1521         struct ppp *ppp;
1522
1523         spin_lock_bh(&pch->downl);
1524         if (pch->chan) {
1525                 while (!skb_queue_empty(&pch->file.xq)) {
1526                         skb = skb_dequeue(&pch->file.xq);
1527                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1528                                 /* put the packet back and try again later */
1529                                 skb_queue_head(&pch->file.xq, skb);
1530                                 break;
1531                         }
1532                 }
1533         } else {
1534                 /* channel got deregistered */
1535                 skb_queue_purge(&pch->file.xq);
1536         }
1537         spin_unlock_bh(&pch->downl);
1538         /* see if there is anything from the attached unit to be sent */
1539         if (skb_queue_empty(&pch->file.xq)) {
1540                 read_lock_bh(&pch->upl);
1541                 ppp = pch->ppp;
1542                 if (ppp)
1543                         ppp_xmit_process(ppp);
1544                 read_unlock_bh(&pch->upl);
1545         }
1546 }
1547
1548 /*
1549  * Receive-side routines.
1550  */
1551
1552 /* misuse a few fields of the skb for MP reconstruction */
1553 #define sequence        priority
1554 #define BEbits          cb[0]
1555
1556 static inline void
1557 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1558 {
1559         ppp_recv_lock(ppp);
1560         if (!ppp->closing)
1561                 ppp_receive_frame(ppp, skb, pch);
1562         else
1563                 kfree_skb(skb);
1564         ppp_recv_unlock(ppp);
1565 }
1566
1567 void
1568 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1569 {
1570         struct channel *pch = chan->ppp;
1571         int proto;
1572
1573         if (!pch) {
1574                 kfree_skb(skb);
1575                 return;
1576         }
1577
1578         read_lock_bh(&pch->upl);
1579         if (!pskb_may_pull(skb, 2)) {
1580                 kfree_skb(skb);
1581                 if (pch->ppp) {
1582                         ++pch->ppp->dev->stats.rx_length_errors;
1583                         ppp_receive_error(pch->ppp);
1584                 }
1585                 goto done;
1586         }
1587
1588         proto = PPP_PROTO(skb);
1589         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1590                 /* put it on the channel queue */
1591                 skb_queue_tail(&pch->file.rq, skb);
1592                 /* drop old frames if queue too long */
1593                 while (pch->file.rq.qlen > PPP_MAX_RQLEN &&
1594                        (skb = skb_dequeue(&pch->file.rq)))
1595                         kfree_skb(skb);
1596                 wake_up_interruptible(&pch->file.rwait);
1597         } else {
1598                 ppp_do_recv(pch->ppp, skb, pch);
1599         }
1600
1601 done:
1602         read_unlock_bh(&pch->upl);
1603 }
1604
1605 /* Put a 0-length skb in the receive queue as an error indication */
1606 void
1607 ppp_input_error(struct ppp_channel *chan, int code)
1608 {
1609         struct channel *pch = chan->ppp;
1610         struct sk_buff *skb;
1611
1612         if (!pch)
1613                 return;
1614
1615         read_lock_bh(&pch->upl);
1616         if (pch->ppp) {
1617                 skb = alloc_skb(0, GFP_ATOMIC);
1618                 if (skb) {
1619                         skb->len = 0;           /* probably unnecessary */
1620                         skb->cb[0] = code;
1621                         ppp_do_recv(pch->ppp, skb, pch);
1622                 }
1623         }
1624         read_unlock_bh(&pch->upl);
1625 }
1626
1627 /*
1628  * We come in here to process a received frame.
1629  * The receive side of the ppp unit is locked.
1630  */
1631 static void
1632 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1633 {
1634         /* note: a 0-length skb is used as an error indication */
1635         if (skb->len > 0) {
1636 #ifdef CONFIG_PPP_MULTILINK
1637                 /* XXX do channel-level decompression here */
1638                 if (PPP_PROTO(skb) == PPP_MP)
1639                         ppp_receive_mp_frame(ppp, skb, pch);
1640                 else
1641 #endif /* CONFIG_PPP_MULTILINK */
1642                         ppp_receive_nonmp_frame(ppp, skb);
1643         } else {
1644                 kfree_skb(skb);
1645                 ppp_receive_error(ppp);
1646         }
1647 }
1648
1649 static void
1650 ppp_receive_error(struct ppp *ppp)
1651 {
1652         ++ppp->dev->stats.rx_errors;
1653         if (ppp->vj)
1654                 slhc_toss(ppp->vj);
1655 }
1656
1657 static void
1658 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1659 {
1660         struct sk_buff *ns;
1661         int proto, len, npi;
1662
1663         /*
1664          * Decompress the frame, if compressed.
1665          * Note that some decompressors need to see uncompressed frames
1666          * that come in as well as compressed frames.
1667          */
1668         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN) &&
1669             (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1670                 skb = ppp_decompress_frame(ppp, skb);
1671
1672         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1673                 goto err;
1674
1675         proto = PPP_PROTO(skb);
1676         switch (proto) {
1677         case PPP_VJC_COMP:
1678                 /* decompress VJ compressed packets */
1679                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1680                         goto err;
1681
1682                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1683                         /* copy to a new sk_buff with more tailroom */
1684                         ns = dev_alloc_skb(skb->len + 128);
1685                         if (!ns) {
1686                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1687                                 goto err;
1688                         }
1689                         skb_reserve(ns, 2);
1690                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1691                         kfree_skb(skb);
1692                         skb = ns;
1693                 }
1694                 else
1695                         skb->ip_summed = CHECKSUM_NONE;
1696
1697                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1698                 if (len <= 0) {
1699                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1700                         goto err;
1701                 }
1702                 len += 2;
1703                 if (len > skb->len)
1704                         skb_put(skb, len - skb->len);
1705                 else if (len < skb->len)
1706                         skb_trim(skb, len);
1707                 proto = PPP_IP;
1708                 break;
1709
1710         case PPP_VJC_UNCOMP:
1711                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1712                         goto err;
1713
1714                 /* Until we fix the decompressor need to make sure
1715                  * data portion is linear.
1716                  */
1717                 if (!pskb_may_pull(skb, skb->len))
1718                         goto err;
1719
1720                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1721                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1722                         goto err;
1723                 }
1724                 proto = PPP_IP;
1725                 break;
1726
1727         case PPP_CCP:
1728                 ppp_ccp_peek(ppp, skb, 1);
1729                 break;
1730         }
1731
1732         ++ppp->dev->stats.rx_packets;
1733         ppp->dev->stats.rx_bytes += skb->len - 2;
1734
1735         npi = proto_to_npindex(proto);
1736         if (npi < 0) {
1737                 /* control or unknown frame - pass it to pppd */
1738                 skb_queue_tail(&ppp->file.rq, skb);
1739                 /* limit queue length by dropping old frames */
1740                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN &&
1741                        (skb = skb_dequeue(&ppp->file.rq)))
1742                         kfree_skb(skb);
1743                 /* wake up any process polling or blocking on read */
1744                 wake_up_interruptible(&ppp->file.rwait);
1745
1746         } else {
1747                 /* network protocol frame - give it to the kernel */
1748
1749 #ifdef CONFIG_PPP_FILTER
1750                 /* check if the packet passes the pass and active filters */
1751                 /* the filter instructions are constructed assuming
1752                    a four-byte PPP header on each packet */
1753                 if (ppp->pass_filter || ppp->active_filter) {
1754                         if (skb_cloned(skb) &&
1755                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1756                                 goto err;
1757
1758                         *skb_push(skb, 2) = 0;
1759                         if (ppp->pass_filter &&
1760                             sk_run_filter(skb, ppp->pass_filter,
1761                                           ppp->pass_len) == 0) {
1762                                 if (ppp->debug & 1)
1763                                         printk(KERN_DEBUG "PPP: inbound frame "
1764                                                "not passed\n");
1765                                 kfree_skb(skb);
1766                                 return;
1767                         }
1768                         if (!(ppp->active_filter &&
1769                               sk_run_filter(skb, ppp->active_filter,
1770                                             ppp->active_len) == 0))
1771                                 ppp->last_recv = jiffies;
1772                         __skb_pull(skb, 2);
1773                 } else
1774 #endif /* CONFIG_PPP_FILTER */
1775                         ppp->last_recv = jiffies;
1776
1777                 if ((ppp->dev->flags & IFF_UP) == 0 ||
1778                     ppp->npmode[npi] != NPMODE_PASS) {
1779                         kfree_skb(skb);
1780                 } else {
1781                         /* chop off protocol */
1782                         skb_pull_rcsum(skb, 2);
1783                         skb->dev = ppp->dev;
1784                         skb->protocol = htons(npindex_to_ethertype[npi]);
1785                         skb_reset_mac_header(skb);
1786                         netif_rx(skb);
1787                 }
1788         }
1789         return;
1790
1791  err:
1792         kfree_skb(skb);
1793         ppp_receive_error(ppp);
1794 }
1795
1796 static struct sk_buff *
1797 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1798 {
1799         int proto = PPP_PROTO(skb);
1800         struct sk_buff *ns;
1801         int len;
1802
1803         /* Until we fix all the decompressor's need to make sure
1804          * data portion is linear.
1805          */
1806         if (!pskb_may_pull(skb, skb->len))
1807                 goto err;
1808
1809         if (proto == PPP_COMP) {
1810                 int obuff_size;
1811
1812                 switch(ppp->rcomp->compress_proto) {
1813                 case CI_MPPE:
1814                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1815                         break;
1816                 default:
1817                         obuff_size = ppp->mru + PPP_HDRLEN;
1818                         break;
1819                 }
1820
1821                 ns = dev_alloc_skb(obuff_size);
1822                 if (!ns) {
1823                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1824                         goto err;
1825                 }
1826                 /* the decompressor still expects the A/C bytes in the hdr */
1827                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1828                                 skb->len + 2, ns->data, obuff_size);
1829                 if (len < 0) {
1830                         /* Pass the compressed frame to pppd as an
1831                            error indication. */
1832                         if (len == DECOMP_FATALERROR)
1833                                 ppp->rstate |= SC_DC_FERROR;
1834                         kfree_skb(ns);
1835                         goto err;
1836                 }
1837
1838                 kfree_skb(skb);
1839                 skb = ns;
1840                 skb_put(skb, len);
1841                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1842
1843         } else {
1844                 /* Uncompressed frame - pass to decompressor so it
1845                    can update its dictionary if necessary. */
1846                 if (ppp->rcomp->incomp)
1847                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1848                                            skb->len + 2);
1849         }
1850
1851         return skb;
1852
1853  err:
1854         ppp->rstate |= SC_DC_ERROR;
1855         ppp_receive_error(ppp);
1856         return skb;
1857 }
1858
1859 #ifdef CONFIG_PPP_MULTILINK
1860 /*
1861  * Receive a multilink frame.
1862  * We put it on the reconstruction queue and then pull off
1863  * as many completed frames as we can.
1864  */
1865 static void
1866 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1867 {
1868         u32 mask, seq;
1869         struct channel *ch;
1870         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1871
1872         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1873                 goto err;               /* no good, throw it away */
1874
1875         /* Decode sequence number and begin/end bits */
1876         if (ppp->flags & SC_MP_SHORTSEQ) {
1877                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1878                 mask = 0xfff;
1879         } else {
1880                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1881                 mask = 0xffffff;
1882         }
1883         skb->BEbits = skb->data[2];
1884         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1885
1886         /*
1887          * Do protocol ID decompression on the first fragment of each packet.
1888          */
1889         if ((skb->BEbits & B) && (skb->data[0] & 1))
1890                 *skb_push(skb, 1) = 0;
1891
1892         /*
1893          * Expand sequence number to 32 bits, making it as close
1894          * as possible to ppp->minseq.
1895          */
1896         seq |= ppp->minseq & ~mask;
1897         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1898                 seq += mask + 1;
1899         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1900                 seq -= mask + 1;        /* should never happen */
1901         skb->sequence = seq;
1902         pch->lastseq = seq;
1903
1904         /*
1905          * If this packet comes before the next one we were expecting,
1906          * drop it.
1907          */
1908         if (seq_before(seq, ppp->nextseq)) {
1909                 kfree_skb(skb);
1910                 ++ppp->dev->stats.rx_dropped;
1911                 ppp_receive_error(ppp);
1912                 return;
1913         }
1914
1915         /*
1916          * Reevaluate minseq, the minimum over all channels of the
1917          * last sequence number received on each channel.  Because of
1918          * the increasing sequence number rule, we know that any fragment
1919          * before `minseq' which hasn't arrived is never going to arrive.
1920          * The list of channels can't change because we have the receive
1921          * side of the ppp unit locked.
1922          */
1923         list_for_each_entry(ch, &ppp->channels, clist) {
1924                 if (seq_before(ch->lastseq, seq))
1925                         seq = ch->lastseq;
1926         }
1927         if (seq_before(ppp->minseq, seq))
1928                 ppp->minseq = seq;
1929
1930         /* Put the fragment on the reconstruction queue */
1931         ppp_mp_insert(ppp, skb);
1932
1933         /* If the queue is getting long, don't wait any longer for packets
1934            before the start of the queue. */
1935         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
1936                 struct sk_buff *skb = skb_peek(&ppp->mrq);
1937                 if (seq_before(ppp->minseq, skb->sequence))
1938                         ppp->minseq = skb->sequence;
1939         }
1940
1941         /* Pull completed packets off the queue and receive them. */
1942         while ((skb = ppp_mp_reconstruct(ppp))) {
1943                 if (pskb_may_pull(skb, 2))
1944                         ppp_receive_nonmp_frame(ppp, skb);
1945                 else {
1946                         ++ppp->dev->stats.rx_length_errors;
1947                         kfree_skb(skb);
1948                         ppp_receive_error(ppp);
1949                 }
1950         }
1951
1952         return;
1953
1954  err:
1955         kfree_skb(skb);
1956         ppp_receive_error(ppp);
1957 }
1958
1959 /*
1960  * Insert a fragment on the MP reconstruction queue.
1961  * The queue is ordered by increasing sequence number.
1962  */
1963 static void
1964 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1965 {
1966         struct sk_buff *p;
1967         struct sk_buff_head *list = &ppp->mrq;
1968         u32 seq = skb->sequence;
1969
1970         /* N.B. we don't need to lock the list lock because we have the
1971            ppp unit receive-side lock. */
1972         skb_queue_walk(list, p) {
1973                 if (seq_before(seq, p->sequence))
1974                         break;
1975         }
1976         __skb_queue_before(list, p, skb);
1977 }
1978
1979 /*
1980  * Reconstruct a packet from the MP fragment queue.
1981  * We go through increasing sequence numbers until we find a
1982  * complete packet, or we get to the sequence number for a fragment
1983  * which hasn't arrived but might still do so.
1984  */
1985 static struct sk_buff *
1986 ppp_mp_reconstruct(struct ppp *ppp)
1987 {
1988         u32 seq = ppp->nextseq;
1989         u32 minseq = ppp->minseq;
1990         struct sk_buff_head *list = &ppp->mrq;
1991         struct sk_buff *p, *next;
1992         struct sk_buff *head, *tail;
1993         struct sk_buff *skb = NULL;
1994         int lost = 0, len = 0;
1995
1996         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1997                 return NULL;
1998         head = list->next;
1999         tail = NULL;
2000         for (p = head; p != (struct sk_buff *) list; p = next) {
2001                 next = p->next;
2002                 if (seq_before(p->sequence, seq)) {
2003                         /* this can't happen, anyway ignore the skb */
2004                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
2005                                p->sequence, seq);
2006                         head = next;
2007                         continue;
2008                 }
2009                 if (p->sequence != seq) {
2010                         /* Fragment `seq' is missing.  If it is after
2011                            minseq, it might arrive later, so stop here. */
2012                         if (seq_after(seq, minseq))
2013                                 break;
2014                         /* Fragment `seq' is lost, keep going. */
2015                         lost = 1;
2016                         seq = seq_before(minseq, p->sequence)?
2017                                 minseq + 1: p->sequence;
2018                         next = p;
2019                         continue;
2020                 }
2021
2022                 /*
2023                  * At this point we know that all the fragments from
2024                  * ppp->nextseq to seq are either present or lost.
2025                  * Also, there are no complete packets in the queue
2026                  * that have no missing fragments and end before this
2027                  * fragment.
2028                  */
2029
2030                 /* B bit set indicates this fragment starts a packet */
2031                 if (p->BEbits & B) {
2032                         head = p;
2033                         lost = 0;
2034                         len = 0;
2035                 }
2036
2037                 len += p->len;
2038
2039                 /* Got a complete packet yet? */
2040                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
2041                         if (len > ppp->mrru + 2) {
2042                                 ++ppp->dev->stats.rx_length_errors;
2043                                 printk(KERN_DEBUG "PPP: reconstructed packet"
2044                                        " is too long (%d)\n", len);
2045                         } else if (p == head) {
2046                                 /* fragment is complete packet - reuse skb */
2047                                 tail = p;
2048                                 skb = skb_get(p);
2049                                 break;
2050                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
2051                                 ++ppp->dev->stats.rx_missed_errors;
2052                                 printk(KERN_DEBUG "PPP: no memory for "
2053                                        "reconstructed packet");
2054                         } else {
2055                                 tail = p;
2056                                 break;
2057                         }
2058                         ppp->nextseq = seq + 1;
2059                 }
2060
2061                 /*
2062                  * If this is the ending fragment of a packet,
2063                  * and we haven't found a complete valid packet yet,
2064                  * we can discard up to and including this fragment.
2065                  */
2066                 if (p->BEbits & E)
2067                         head = next;
2068
2069                 ++seq;
2070         }
2071
2072         /* If we have a complete packet, copy it all into one skb. */
2073         if (tail != NULL) {
2074                 /* If we have discarded any fragments,
2075                    signal a receive error. */
2076                 if (head->sequence != ppp->nextseq) {
2077                         if (ppp->debug & 1)
2078                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
2079                                        ppp->nextseq, head->sequence-1);
2080                         ++ppp->dev->stats.rx_dropped;
2081                         ppp_receive_error(ppp);
2082                 }
2083
2084                 if (head != tail)
2085                         /* copy to a single skb */
2086                         for (p = head; p != tail->next; p = p->next)
2087                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
2088                 ppp->nextseq = tail->sequence + 1;
2089                 head = tail->next;
2090         }
2091
2092         /* Discard all the skbuffs that we have copied the data out of
2093            or that we can't use. */
2094         while ((p = list->next) != head) {
2095                 __skb_unlink(p, list);
2096                 kfree_skb(p);
2097         }
2098
2099         return skb;
2100 }
2101 #endif /* CONFIG_PPP_MULTILINK */
2102
2103 /*
2104  * Channel interface.
2105  */
2106
2107 /* Create a new, unattached ppp channel. */
2108 int ppp_register_channel(struct ppp_channel *chan)
2109 {
2110         return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2111 }
2112
2113 /* Create a new, unattached ppp channel for specified net. */
2114 int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2115 {
2116         struct channel *pch;
2117         struct ppp_net *pn;
2118
2119         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2120         if (!pch)
2121                 return -ENOMEM;
2122
2123         pn = ppp_pernet(net);
2124
2125         pch->ppp = NULL;
2126         pch->chan = chan;
2127         pch->chan_net = net;
2128         chan->ppp = pch;
2129         init_ppp_file(&pch->file, CHANNEL);
2130         pch->file.hdrlen = chan->hdrlen;
2131 #ifdef CONFIG_PPP_MULTILINK
2132         pch->lastseq = -1;
2133 #endif /* CONFIG_PPP_MULTILINK */
2134         init_rwsem(&pch->chan_sem);
2135         spin_lock_init(&pch->downl);
2136         rwlock_init(&pch->upl);
2137
2138         spin_lock_bh(&pn->all_channels_lock);
2139         pch->file.index = ++pn->last_channel_index;
2140         list_add(&pch->list, &pn->new_channels);
2141         atomic_inc(&channel_count);
2142         spin_unlock_bh(&pn->all_channels_lock);
2143
2144         return 0;
2145 }
2146
2147 /*
2148  * Return the index of a channel.
2149  */
2150 int ppp_channel_index(struct ppp_channel *chan)
2151 {
2152         struct channel *pch = chan->ppp;
2153
2154         if (pch)
2155                 return pch->file.index;
2156         return -1;
2157 }
2158
2159 /*
2160  * Return the PPP unit number to which a channel is connected.
2161  */
2162 int ppp_unit_number(struct ppp_channel *chan)
2163 {
2164         struct channel *pch = chan->ppp;
2165         int unit = -1;
2166
2167         if (pch) {
2168                 read_lock_bh(&pch->upl);
2169                 if (pch->ppp)
2170                         unit = pch->ppp->file.index;
2171                 read_unlock_bh(&pch->upl);
2172         }
2173         return unit;
2174 }
2175
2176 /*
2177  * Disconnect a channel from the generic layer.
2178  * This must be called in process context.
2179  */
2180 void
2181 ppp_unregister_channel(struct ppp_channel *chan)
2182 {
2183         struct channel *pch = chan->ppp;
2184         struct ppp_net *pn;
2185
2186         if (!pch)
2187                 return;         /* should never happen */
2188
2189         chan->ppp = NULL;
2190
2191         /*
2192          * This ensures that we have returned from any calls into the
2193          * the channel's start_xmit or ioctl routine before we proceed.
2194          */
2195         down_write(&pch->chan_sem);
2196         spin_lock_bh(&pch->downl);
2197         pch->chan = NULL;
2198         spin_unlock_bh(&pch->downl);
2199         up_write(&pch->chan_sem);
2200         ppp_disconnect_channel(pch);
2201
2202         pn = ppp_pernet(pch->chan_net);
2203         spin_lock_bh(&pn->all_channels_lock);
2204         list_del(&pch->list);
2205         spin_unlock_bh(&pn->all_channels_lock);
2206
2207         pch->file.dead = 1;
2208         wake_up_interruptible(&pch->file.rwait);
2209         if (atomic_dec_and_test(&pch->file.refcnt))
2210                 ppp_destroy_channel(pch);
2211 }
2212
2213 /*
2214  * Callback from a channel when it can accept more to transmit.
2215  * This should be called at BH/softirq level, not interrupt level.
2216  */
2217 void
2218 ppp_output_wakeup(struct ppp_channel *chan)
2219 {
2220         struct channel *pch = chan->ppp;
2221
2222         if (!pch)
2223                 return;
2224         ppp_channel_push(pch);
2225 }
2226
2227 /*
2228  * Compression control.
2229  */
2230
2231 /* Process the PPPIOCSCOMPRESS ioctl. */
2232 static int
2233 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2234 {
2235         int err;
2236         struct compressor *cp, *ocomp;
2237         struct ppp_option_data data;
2238         void *state, *ostate;
2239         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2240
2241         err = -EFAULT;
2242         if (copy_from_user(&data, (void __user *) arg, sizeof(data)) ||
2243             (data.length <= CCP_MAX_OPTION_LENGTH &&
2244              copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2245                 goto out;
2246         err = -EINVAL;
2247         if (data.length > CCP_MAX_OPTION_LENGTH ||
2248             ccp_option[1] < 2 || ccp_option[1] > data.length)
2249                 goto out;
2250
2251         cp = try_then_request_module(
2252                 find_compressor(ccp_option[0]),
2253                 "ppp-compress-%d", ccp_option[0]);
2254         if (!cp)
2255                 goto out;
2256
2257         err = -ENOBUFS;
2258         if (data.transmit) {
2259                 state = cp->comp_alloc(ccp_option, data.length);
2260                 if (state) {
2261                         ppp_xmit_lock(ppp);
2262                         ppp->xstate &= ~SC_COMP_RUN;
2263                         ocomp = ppp->xcomp;
2264                         ostate = ppp->xc_state;
2265                         ppp->xcomp = cp;
2266                         ppp->xc_state = state;
2267                         ppp_xmit_unlock(ppp);
2268                         if (ostate) {
2269                                 ocomp->comp_free(ostate);
2270                                 module_put(ocomp->owner);
2271                         }
2272                         err = 0;
2273                 } else
2274                         module_put(cp->owner);
2275
2276         } else {
2277                 state = cp->decomp_alloc(ccp_option, data.length);
2278                 if (state) {
2279                         ppp_recv_lock(ppp);
2280                         ppp->rstate &= ~SC_DECOMP_RUN;
2281                         ocomp = ppp->rcomp;
2282                         ostate = ppp->rc_state;
2283                         ppp->rcomp = cp;
2284                         ppp->rc_state = state;
2285                         ppp_recv_unlock(ppp);
2286                         if (ostate) {
2287                                 ocomp->decomp_free(ostate);
2288                                 module_put(ocomp->owner);
2289                         }
2290                         err = 0;
2291                 } else
2292                         module_put(cp->owner);
2293         }
2294
2295  out:
2296         return err;
2297 }
2298
2299 /*
2300  * Look at a CCP packet and update our state accordingly.
2301  * We assume the caller has the xmit or recv path locked.
2302  */
2303 static void
2304 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2305 {
2306         unsigned char *dp;
2307         int len;
2308
2309         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2310                 return; /* no header */
2311         dp = skb->data + 2;
2312
2313         switch (CCP_CODE(dp)) {
2314         case CCP_CONFREQ:
2315
2316                 /* A ConfReq starts negotiation of compression
2317                  * in one direction of transmission,
2318                  * and hence brings it down...but which way?
2319                  *
2320                  * Remember:
2321                  * A ConfReq indicates what the sender would like to receive
2322                  */
2323                 if(inbound)
2324                         /* He is proposing what I should send */
2325                         ppp->xstate &= ~SC_COMP_RUN;
2326                 else
2327                         /* I am proposing to what he should send */
2328                         ppp->rstate &= ~SC_DECOMP_RUN;
2329
2330                 break;
2331
2332         case CCP_TERMREQ:
2333         case CCP_TERMACK:
2334                 /*
2335                  * CCP is going down, both directions of transmission
2336                  */
2337                 ppp->rstate &= ~SC_DECOMP_RUN;
2338                 ppp->xstate &= ~SC_COMP_RUN;
2339                 break;
2340
2341         case CCP_CONFACK:
2342                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2343                         break;
2344                 len = CCP_LENGTH(dp);
2345                 if (!pskb_may_pull(skb, len + 2))
2346                         return;         /* too short */
2347                 dp += CCP_HDRLEN;
2348                 len -= CCP_HDRLEN;
2349                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2350                         break;
2351                 if (inbound) {
2352                         /* we will start receiving compressed packets */
2353                         if (!ppp->rc_state)
2354                                 break;
2355                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2356                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2357                                 ppp->rstate |= SC_DECOMP_RUN;
2358                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2359                         }
2360                 } else {
2361                         /* we will soon start sending compressed packets */
2362                         if (!ppp->xc_state)
2363                                 break;
2364                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2365                                         ppp->file.index, 0, ppp->debug))
2366                                 ppp->xstate |= SC_COMP_RUN;
2367                 }
2368                 break;
2369
2370         case CCP_RESETACK:
2371                 /* reset the [de]compressor */
2372                 if ((ppp->flags & SC_CCP_UP) == 0)
2373                         break;
2374                 if (inbound) {
2375                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2376                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2377                                 ppp->rstate &= ~SC_DC_ERROR;
2378                         }
2379                 } else {
2380                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2381                                 ppp->xcomp->comp_reset(ppp->xc_state);
2382                 }
2383                 break;
2384         }
2385 }
2386
2387 /* Free up compression resources. */
2388 static void
2389 ppp_ccp_closed(struct ppp *ppp)
2390 {
2391         void *xstate, *rstate;
2392         struct compressor *xcomp, *rcomp;
2393
2394         ppp_lock(ppp);
2395         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2396         ppp->xstate = 0;
2397         xcomp = ppp->xcomp;
2398         xstate = ppp->xc_state;
2399         ppp->xc_state = NULL;
2400         ppp->rstate = 0;
2401         rcomp = ppp->rcomp;
2402         rstate = ppp->rc_state;
2403         ppp->rc_state = NULL;
2404         ppp_unlock(ppp);
2405
2406         if (xstate) {
2407                 xcomp->comp_free(xstate);
2408                 module_put(xcomp->owner);
2409         }
2410         if (rstate) {
2411                 rcomp->decomp_free(rstate);
2412                 module_put(rcomp->owner);
2413         }
2414 }
2415
2416 /* List of compressors. */
2417 static LIST_HEAD(compressor_list);
2418 static DEFINE_SPINLOCK(compressor_list_lock);
2419
2420 struct compressor_entry {
2421         struct list_head list;
2422         struct compressor *comp;
2423 };
2424
2425 static struct compressor_entry *
2426 find_comp_entry(int proto)
2427 {
2428         struct compressor_entry *ce;
2429
2430         list_for_each_entry(ce, &compressor_list, list) {
2431                 if (ce->comp->compress_proto == proto)
2432                         return ce;
2433         }
2434         return NULL;
2435 }
2436
2437 /* Register a compressor */
2438 int
2439 ppp_register_compressor(struct compressor *cp)
2440 {
2441         struct compressor_entry *ce;
2442         int ret;
2443         spin_lock(&compressor_list_lock);
2444         ret = -EEXIST;
2445         if (find_comp_entry(cp->compress_proto))
2446                 goto out;
2447         ret = -ENOMEM;
2448         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2449         if (!ce)
2450                 goto out;
2451         ret = 0;
2452         ce->comp = cp;
2453         list_add(&ce->list, &compressor_list);
2454  out:
2455         spin_unlock(&compressor_list_lock);
2456         return ret;
2457 }
2458
2459 /* Unregister a compressor */
2460 void
2461 ppp_unregister_compressor(struct compressor *cp)
2462 {
2463         struct compressor_entry *ce;
2464
2465         spin_lock(&compressor_list_lock);
2466         ce = find_comp_entry(cp->compress_proto);
2467         if (ce && ce->comp == cp) {
2468                 list_del(&ce->list);
2469                 kfree(ce);
2470         }
2471         spin_unlock(&compressor_list_lock);
2472 }
2473
2474 /* Find a compressor. */
2475 static struct compressor *
2476 find_compressor(int type)
2477 {
2478         struct compressor_entry *ce;
2479         struct compressor *cp = NULL;
2480
2481         spin_lock(&compressor_list_lock);
2482         ce = find_comp_entry(type);
2483         if (ce) {
2484                 cp = ce->comp;
2485                 if (!try_module_get(cp->owner))
2486                         cp = NULL;
2487         }
2488         spin_unlock(&compressor_list_lock);
2489         return cp;
2490 }
2491
2492 /*
2493  * Miscelleneous stuff.
2494  */
2495
2496 static void
2497 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2498 {
2499         struct slcompress *vj = ppp->vj;
2500
2501         memset(st, 0, sizeof(*st));
2502         st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
2503         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2504         st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
2505         st->p.ppp_opackets = ppp->dev->stats.tx_packets;
2506         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2507         st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
2508         if (!vj)
2509                 return;
2510         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2511         st->vj.vjs_compressed = vj->sls_o_compressed;
2512         st->vj.vjs_searches = vj->sls_o_searches;
2513         st->vj.vjs_misses = vj->sls_o_misses;
2514         st->vj.vjs_errorin = vj->sls_i_error;
2515         st->vj.vjs_tossed = vj->sls_i_tossed;
2516         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2517         st->vj.vjs_compressedin = vj->sls_i_compressed;
2518 }
2519
2520 /*
2521  * Stuff for handling the lists of ppp units and channels
2522  * and for initialization.
2523  */
2524
2525 /*
2526  * Create a new ppp interface unit.  Fails if it can't allocate memory
2527  * or if there is already a unit with the requested number.
2528  * unit == -1 means allocate a new number.
2529  */
2530 static struct ppp *
2531 ppp_create_interface(struct net *net, int unit, int *retp)
2532 {
2533         struct ppp *ppp;
2534         struct ppp_net *pn;
2535         struct net_device *dev = NULL;
2536         int ret = -ENOMEM;
2537         int i;
2538
2539         dev = alloc_netdev(sizeof(struct ppp), "", ppp_setup);
2540         if (!dev)
2541                 goto out1;
2542
2543         pn = ppp_pernet(net);
2544
2545         ppp = netdev_priv(dev);
2546         ppp->dev = dev;
2547         ppp->mru = PPP_MRU;
2548         init_ppp_file(&ppp->file, INTERFACE);
2549         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2550         for (i = 0; i < NUM_NP; ++i)
2551                 ppp->npmode[i] = NPMODE_PASS;
2552         INIT_LIST_HEAD(&ppp->channels);
2553         spin_lock_init(&ppp->rlock);
2554         spin_lock_init(&ppp->wlock);
2555 #ifdef CONFIG_PPP_MULTILINK
2556         ppp->minseq = -1;
2557         skb_queue_head_init(&ppp->mrq);
2558 #endif /* CONFIG_PPP_MULTILINK */
2559
2560         /*
2561          * drum roll: don't forget to set
2562          * the net device is belong to
2563          */
2564         dev_net_set(dev, net);
2565
2566         ret = -EEXIST;
2567         mutex_lock(&pn->all_ppp_mutex);
2568
2569         if (unit < 0) {
2570                 unit = unit_get(&pn->units_idr, ppp);
2571                 if (unit < 0) {
2572                         *retp = unit;
2573                         goto out2;
2574                 }
2575         } else {
2576                 if (unit_find(&pn->units_idr, unit))
2577                         goto out2; /* unit already exists */
2578                 /*
2579                  * if caller need a specified unit number
2580                  * lets try to satisfy him, otherwise --
2581                  * he should better ask us for new unit number
2582                  *
2583                  * NOTE: yes I know that returning EEXIST it's not
2584                  * fair but at least pppd will ask us to allocate
2585                  * new unit in this case so user is happy :)
2586                  */
2587                 unit = unit_set(&pn->units_idr, ppp, unit);
2588                 if (unit < 0)
2589                         goto out2;
2590         }
2591
2592         /* Initialize the new ppp unit */
2593         ppp->file.index = unit;
2594         sprintf(dev->name, "ppp%d", unit);
2595
2596         ret = register_netdev(dev);
2597         if (ret != 0) {
2598                 unit_put(&pn->units_idr, unit);
2599                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2600                        dev->name, ret);
2601                 goto out2;
2602         }
2603
2604         ppp->ppp_net = net;
2605
2606         atomic_inc(&ppp_unit_count);
2607         mutex_unlock(&pn->all_ppp_mutex);
2608
2609         *retp = 0;
2610         return ppp;
2611
2612 out2:
2613         mutex_unlock(&pn->all_ppp_mutex);
2614         free_netdev(dev);
2615 out1:
2616         *retp = ret;
2617         return NULL;
2618 }
2619
2620 /*
2621  * Initialize a ppp_file structure.
2622  */
2623 static void
2624 init_ppp_file(struct ppp_file *pf, int kind)
2625 {
2626         pf->kind = kind;
2627         skb_queue_head_init(&pf->xq);
2628         skb_queue_head_init(&pf->rq);
2629         atomic_set(&pf->refcnt, 1);
2630         init_waitqueue_head(&pf->rwait);
2631 }
2632
2633 /*
2634  * Take down a ppp interface unit - called when the owning file
2635  * (the one that created the unit) is closed or detached.
2636  */
2637 static void ppp_shutdown_interface(struct ppp *ppp)
2638 {
2639         struct ppp_net *pn;
2640
2641         pn = ppp_pernet(ppp->ppp_net);
2642         mutex_lock(&pn->all_ppp_mutex);
2643
2644         /* This will call dev_close() for us. */
2645         ppp_lock(ppp);
2646         if (!ppp->closing) {
2647                 ppp->closing = 1;
2648                 ppp_unlock(ppp);
2649                 unregister_netdev(ppp->dev);
2650         } else
2651                 ppp_unlock(ppp);
2652
2653         unit_put(&pn->units_idr, ppp->file.index);
2654         ppp->file.dead = 1;
2655         ppp->owner = NULL;
2656         wake_up_interruptible(&ppp->file.rwait);
2657
2658         mutex_unlock(&pn->all_ppp_mutex);
2659 }
2660
2661 /*
2662  * Free the memory used by a ppp unit.  This is only called once
2663  * there are no channels connected to the unit and no file structs
2664  * that reference the unit.
2665  */
2666 static void ppp_destroy_interface(struct ppp *ppp)
2667 {
2668         atomic_dec(&ppp_unit_count);
2669
2670         if (!ppp->file.dead || ppp->n_channels) {
2671                 /* "can't happen" */
2672                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2673                        "n_channels=%d !\n", ppp, ppp->file.dead,
2674                        ppp->n_channels);
2675                 return;
2676         }
2677
2678         ppp_ccp_closed(ppp);
2679         if (ppp->vj) {
2680                 slhc_free(ppp->vj);
2681                 ppp->vj = NULL;
2682         }
2683         skb_queue_purge(&ppp->file.xq);
2684         skb_queue_purge(&ppp->file.rq);
2685 #ifdef CONFIG_PPP_MULTILINK
2686         skb_queue_purge(&ppp->mrq);
2687 #endif /* CONFIG_PPP_MULTILINK */
2688 #ifdef CONFIG_PPP_FILTER
2689         kfree(ppp->pass_filter);
2690         ppp->pass_filter = NULL;
2691         kfree(ppp->active_filter);
2692         ppp->active_filter = NULL;
2693 #endif /* CONFIG_PPP_FILTER */
2694
2695         kfree_skb(ppp->xmit_pending);
2696
2697         free_netdev(ppp->dev);
2698 }
2699
2700 /*
2701  * Locate an existing ppp unit.
2702  * The caller should have locked the all_ppp_mutex.
2703  */
2704 static struct ppp *
2705 ppp_find_unit(struct ppp_net *pn, int unit)
2706 {
2707         return unit_find(&pn->units_idr, unit);
2708 }
2709
2710 /*
2711  * Locate an existing ppp channel.
2712  * The caller should have locked the all_channels_lock.
2713  * First we look in the new_channels list, then in the
2714  * all_channels list.  If found in the new_channels list,
2715  * we move it to the all_channels list.  This is for speed
2716  * when we have a lot of channels in use.
2717  */
2718 static struct channel *
2719 ppp_find_channel(struct ppp_net *pn, int unit)
2720 {
2721         struct channel *pch;
2722
2723         list_for_each_entry(pch, &pn->new_channels, list) {
2724                 if (pch->file.index == unit) {
2725                         list_move(&pch->list, &pn->all_channels);
2726                         return pch;
2727                 }
2728         }
2729
2730         list_for_each_entry(pch, &pn->all_channels, list) {
2731                 if (pch->file.index == unit)
2732                         return pch;
2733         }
2734
2735         return NULL;
2736 }
2737
2738 /*
2739  * Connect a PPP channel to a PPP interface unit.
2740  */
2741 static int
2742 ppp_connect_channel(struct channel *pch, int unit)
2743 {
2744         struct ppp *ppp;
2745         struct ppp_net *pn;
2746         int ret = -ENXIO;
2747         int hdrlen;
2748
2749         pn = ppp_pernet(pch->chan_net);
2750
2751         mutex_lock(&pn->all_ppp_mutex);
2752         ppp = ppp_find_unit(pn, unit);
2753         if (!ppp)
2754                 goto out;
2755         write_lock_bh(&pch->upl);
2756         ret = -EINVAL;
2757         if (pch->ppp)
2758                 goto outl;
2759
2760         ppp_lock(ppp);
2761         if (pch->file.hdrlen > ppp->file.hdrlen)
2762                 ppp->file.hdrlen = pch->file.hdrlen;
2763         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2764         if (hdrlen > ppp->dev->hard_header_len)
2765                 ppp->dev->hard_header_len = hdrlen;
2766         list_add_tail(&pch->clist, &ppp->channels);
2767         ++ppp->n_channels;
2768         pch->ppp = ppp;
2769         atomic_inc(&ppp->file.refcnt);
2770         ppp_unlock(ppp);
2771         ret = 0;
2772
2773  outl:
2774         write_unlock_bh(&pch->upl);
2775  out:
2776         mutex_unlock(&pn->all_ppp_mutex);
2777         return ret;
2778 }
2779
2780 /*
2781  * Disconnect a channel from its ppp unit.
2782  */
2783 static int
2784 ppp_disconnect_channel(struct channel *pch)
2785 {
2786         struct ppp *ppp;
2787         int err = -EINVAL;
2788
2789         write_lock_bh(&pch->upl);
2790         ppp = pch->ppp;
2791         pch->ppp = NULL;
2792         write_unlock_bh(&pch->upl);
2793         if (ppp) {
2794                 /* remove it from the ppp unit's list */
2795                 ppp_lock(ppp);
2796                 list_del(&pch->clist);
2797                 if (--ppp->n_channels == 0)
2798                         wake_up_interruptible(&ppp->file.rwait);
2799                 ppp_unlock(ppp);
2800                 if (atomic_dec_and_test(&ppp->file.refcnt))
2801                         ppp_destroy_interface(ppp);
2802                 err = 0;
2803         }
2804         return err;
2805 }
2806
2807 /*
2808  * Free up the resources used by a ppp channel.
2809  */
2810 static void ppp_destroy_channel(struct channel *pch)
2811 {
2812         atomic_dec(&channel_count);
2813
2814         if (!pch->file.dead) {
2815                 /* "can't happen" */
2816                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2817                        pch);
2818                 return;
2819         }
2820         skb_queue_purge(&pch->file.xq);
2821         skb_queue_purge(&pch->file.rq);
2822         kfree(pch);
2823 }
2824
2825 static void __exit ppp_cleanup(void)
2826 {
2827         /* should never happen */
2828         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2829                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2830         unregister_chrdev(PPP_MAJOR, "ppp");
2831         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2832         class_destroy(ppp_class);
2833         unregister_pernet_device(&ppp_net_ops);
2834 }
2835
2836 /*
2837  * Units handling. Caller must protect concurrent access
2838  * by holding all_ppp_mutex
2839  */
2840
2841 /* associate pointer with specified number */
2842 static int unit_set(struct idr *p, void *ptr, int n)
2843 {
2844         int unit, err;
2845
2846 again:
2847         if (!idr_pre_get(p, GFP_KERNEL)) {
2848                 printk(KERN_ERR "PPP: No free memory for idr\n");
2849                 return -ENOMEM;
2850         }
2851
2852         err = idr_get_new_above(p, ptr, n, &unit);
2853         if (err == -EAGAIN)
2854                 goto again;
2855
2856         if (unit != n) {
2857                 idr_remove(p, unit);
2858                 return -EINVAL;
2859         }
2860
2861         return unit;
2862 }
2863
2864 /* get new free unit number and associate pointer with it */
2865 static int unit_get(struct idr *p, void *ptr)
2866 {
2867         int unit, err;
2868
2869 again:
2870         if (!idr_pre_get(p, GFP_KERNEL)) {
2871                 printk(KERN_ERR "PPP: No free memory for idr\n");
2872                 return -ENOMEM;
2873         }
2874
2875         err = idr_get_new_above(p, ptr, 0, &unit);
2876         if (err == -EAGAIN)
2877                 goto again;
2878
2879         return unit;
2880 }
2881
2882 /* put unit number back to a pool */
2883 static void unit_put(struct idr *p, int n)
2884 {
2885         idr_remove(p, n);
2886 }
2887
2888 /* get pointer associated with the number */
2889 static void *unit_find(struct idr *p, int n)
2890 {
2891         return idr_find(p, n);
2892 }
2893
2894 /* Module/initialization stuff */
2895
2896 module_init(ppp_init);
2897 module_exit(ppp_cleanup);
2898
2899 EXPORT_SYMBOL(ppp_register_net_channel);
2900 EXPORT_SYMBOL(ppp_register_channel);
2901 EXPORT_SYMBOL(ppp_unregister_channel);
2902 EXPORT_SYMBOL(ppp_channel_index);
2903 EXPORT_SYMBOL(ppp_unit_number);
2904 EXPORT_SYMBOL(ppp_input);
2905 EXPORT_SYMBOL(ppp_input_error);
2906 EXPORT_SYMBOL(ppp_output_wakeup);
2907 EXPORT_SYMBOL(ppp_register_compressor);
2908 EXPORT_SYMBOL(ppp_unregister_compressor);
2909 MODULE_LICENSE("GPL");
2910 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2911 MODULE_ALIAS("/dev/ppp");