net: ppp_generic - introduce net-namespace functionality v2
[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 <net/slhc_vj.h>
50 #include <asm/atomic.h>
51
52 #include <linux/nsproxy.h>
53 #include <net/net_namespace.h>
54 #include <net/netns/generic.h>
55
56 #define PPP_VERSION     "2.4.2"
57
58 /*
59  * Network protocols we support.
60  */
61 #define NP_IP   0               /* Internet Protocol V4 */
62 #define NP_IPV6 1               /* Internet Protocol V6 */
63 #define NP_IPX  2               /* IPX protocol */
64 #define NP_AT   3               /* Appletalk protocol */
65 #define NP_MPLS_UC 4            /* MPLS unicast */
66 #define NP_MPLS_MC 5            /* MPLS multicast */
67 #define NUM_NP  6               /* Number of NPs. */
68
69 #define MPHDRLEN        6       /* multilink protocol header length */
70 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
71 #define MIN_FRAG_SIZE   64
72
73 /*
74  * An instance of /dev/ppp can be associated with either a ppp
75  * interface unit or a ppp channel.  In both cases, file->private_data
76  * points to one of these.
77  */
78 struct ppp_file {
79         enum {
80                 INTERFACE=1, CHANNEL
81         }               kind;
82         struct sk_buff_head xq;         /* pppd transmit queue */
83         struct sk_buff_head rq;         /* receive queue for pppd */
84         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
85         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
86         int             hdrlen;         /* space to leave for headers */
87         int             index;          /* interface unit / channel number */
88         int             dead;           /* unit/channel has been shut down */
89 };
90
91 #define PF_TO_X(pf, X)          container_of(pf, X, file)
92
93 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
94 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
95
96 /*
97  * Data structure describing one ppp unit.
98  * A ppp unit corresponds to a ppp network interface device
99  * and represents a multilink bundle.
100  * It can have 0 or more ppp channels connected to it.
101  */
102 struct ppp {
103         struct ppp_file file;           /* stuff for read/write/poll 0 */
104         struct file     *owner;         /* file that owns this unit 48 */
105         struct list_head channels;      /* list of attached channels 4c */
106         int             n_channels;     /* how many channels are attached 54 */
107         spinlock_t      rlock;          /* lock for receive side 58 */
108         spinlock_t      wlock;          /* lock for transmit side 5c */
109         int             mru;            /* max receive unit 60 */
110         unsigned int    flags;          /* control bits 64 */
111         unsigned int    xstate;         /* transmit state bits 68 */
112         unsigned int    rstate;         /* receive state bits 6c */
113         int             debug;          /* debug flags 70 */
114         struct slcompress *vj;          /* state for VJ header compression */
115         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
116         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
117         struct compressor *xcomp;       /* transmit packet compressor 8c */
118         void            *xc_state;      /* its internal state 90 */
119         struct compressor *rcomp;       /* receive decompressor 94 */
120         void            *rc_state;      /* its internal state 98 */
121         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
122         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
123         struct net_device *dev;         /* network interface device a4 */
124         int             closing;        /* is device closing down? a8 */
125 #ifdef CONFIG_PPP_MULTILINK
126         int             nxchan;         /* next channel to send something on */
127         u32             nxseq;          /* next sequence number to send */
128         int             mrru;           /* MP: max reconst. receive unit */
129         u32             nextseq;        /* MP: seq no of next packet */
130         u32             minseq;         /* MP: min of most recent seqnos */
131         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
132 #endif /* CONFIG_PPP_MULTILINK */
133 #ifdef CONFIG_PPP_FILTER
134         struct sock_filter *pass_filter;        /* filter for packets to pass */
135         struct sock_filter *active_filter;/* filter for pkts to reset idle */
136         unsigned pass_len, active_len;
137 #endif /* CONFIG_PPP_FILTER */
138         struct net      *ppp_net;       /* the net we belong to */
139 };
140
141 /*
142  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
143  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
144  * SC_MUST_COMP
145  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
146  * Bits in xstate: SC_COMP_RUN
147  */
148 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
149                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
150                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
151
152 /*
153  * Private data structure for each channel.
154  * This includes the data structure used for multilink.
155  */
156 struct channel {
157         struct ppp_file file;           /* stuff for read/write/poll */
158         struct list_head list;          /* link in all/new_channels list */
159         struct ppp_channel *chan;       /* public channel data structure */
160         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
161         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
162         struct ppp      *ppp;           /* ppp unit we're connected to */
163         struct net      *chan_net;      /* the net channel belongs to */
164         struct list_head clist;         /* link in list of channels per unit */
165         rwlock_t        upl;            /* protects `ppp' */
166 #ifdef CONFIG_PPP_MULTILINK
167         u8              avail;          /* flag used in multilink stuff */
168         u8              had_frag;       /* >= 1 fragments have been sent */
169         u32             lastseq;        /* MP: last sequence # received */
170 #endif /* CONFIG_PPP_MULTILINK */
171 };
172
173 /*
174  * SMP locking issues:
175  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
176  * list and the ppp.n_channels field, you need to take both locks
177  * before you modify them.
178  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
179  * channel.downl.
180  */
181
182 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
183 static atomic_t channel_count = ATOMIC_INIT(0);
184
185 /* per-net private data for this module */
186 static unsigned int ppp_net_id;
187 struct ppp_net {
188         /* units to ppp mapping */
189         struct idr units_idr;
190
191         /*
192          * all_ppp_mutex protects the units_idr mapping.
193          * It also ensures that finding a ppp unit in the units_idr
194          * map and updating its file.refcnt field is atomic.
195          */
196         struct mutex all_ppp_mutex;
197
198         /* channels */
199         struct list_head all_channels;
200         struct list_head new_channels;
201         int last_channel_index;
202
203         /*
204          * all_channels_lock protects all_channels and
205          * last_channel_index, and the atomicity of find
206          * a channel and updating its file.refcnt field.
207          */
208         spinlock_t all_channels_lock;
209 };
210
211 /* Get the PPP protocol number from a skb */
212 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
213
214 /* We limit the length of ppp->file.rq to this (arbitrary) value */
215 #define PPP_MAX_RQLEN   32
216
217 /*
218  * Maximum number of multilink fragments queued up.
219  * This has to be large enough to cope with the maximum latency of
220  * the slowest channel relative to the others.  Strictly it should
221  * depend on the number of channels and their characteristics.
222  */
223 #define PPP_MP_MAX_QLEN 128
224
225 /* Multilink header bits. */
226 #define B       0x80            /* this fragment begins a packet */
227 #define E       0x40            /* this fragment ends a packet */
228
229 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
230 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
231 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
232
233 /* Prototypes. */
234 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
235                         struct file *file, unsigned int cmd, unsigned long arg);
236 static void ppp_xmit_process(struct ppp *ppp);
237 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
238 static void ppp_push(struct ppp *ppp);
239 static void ppp_channel_push(struct channel *pch);
240 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
241                               struct channel *pch);
242 static void ppp_receive_error(struct ppp *ppp);
243 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
244 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
245                                             struct sk_buff *skb);
246 #ifdef CONFIG_PPP_MULTILINK
247 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
248                                 struct channel *pch);
249 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
250 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
251 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
252 #endif /* CONFIG_PPP_MULTILINK */
253 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
254 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
255 static void ppp_ccp_closed(struct ppp *ppp);
256 static struct compressor *find_compressor(int type);
257 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
258 static struct ppp *ppp_create_interface(struct net *net, int unit, int *retp);
259 static void init_ppp_file(struct ppp_file *pf, int kind);
260 static void ppp_shutdown_interface(struct ppp *ppp);
261 static void ppp_destroy_interface(struct ppp *ppp);
262 static struct ppp *ppp_find_unit(struct ppp_net *pn, int unit);
263 static struct channel *ppp_find_channel(struct ppp_net *pn, int unit);
264 static int ppp_connect_channel(struct channel *pch, int unit);
265 static int ppp_disconnect_channel(struct channel *pch);
266 static void ppp_destroy_channel(struct channel *pch);
267 static int unit_get(struct idr *p, void *ptr);
268 static int unit_set(struct idr *p, void *ptr, int n);
269 static void unit_put(struct idr *p, int n);
270 static void *unit_find(struct idr *p, int n);
271
272 static struct class *ppp_class;
273
274 /* per net-namespace data */
275 static inline struct ppp_net *ppp_pernet(struct net *net)
276 {
277         BUG_ON(!net);
278
279         return net_generic(net, ppp_net_id);
280 }
281
282 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
283 static inline int proto_to_npindex(int proto)
284 {
285         switch (proto) {
286         case PPP_IP:
287                 return NP_IP;
288         case PPP_IPV6:
289                 return NP_IPV6;
290         case PPP_IPX:
291                 return NP_IPX;
292         case PPP_AT:
293                 return NP_AT;
294         case PPP_MPLS_UC:
295                 return NP_MPLS_UC;
296         case PPP_MPLS_MC:
297                 return NP_MPLS_MC;
298         }
299         return -EINVAL;
300 }
301
302 /* Translates an NP index into a PPP protocol number */
303 static const int npindex_to_proto[NUM_NP] = {
304         PPP_IP,
305         PPP_IPV6,
306         PPP_IPX,
307         PPP_AT,
308         PPP_MPLS_UC,
309         PPP_MPLS_MC,
310 };
311
312 /* Translates an ethertype into an NP index */
313 static inline int ethertype_to_npindex(int ethertype)
314 {
315         switch (ethertype) {
316         case ETH_P_IP:
317                 return NP_IP;
318         case ETH_P_IPV6:
319                 return NP_IPV6;
320         case ETH_P_IPX:
321                 return NP_IPX;
322         case ETH_P_PPPTALK:
323         case ETH_P_ATALK:
324                 return NP_AT;
325         case ETH_P_MPLS_UC:
326                 return NP_MPLS_UC;
327         case ETH_P_MPLS_MC:
328                 return NP_MPLS_MC;
329         }
330         return -1;
331 }
332
333 /* Translates an NP index into an ethertype */
334 static const int npindex_to_ethertype[NUM_NP] = {
335         ETH_P_IP,
336         ETH_P_IPV6,
337         ETH_P_IPX,
338         ETH_P_PPPTALK,
339         ETH_P_MPLS_UC,
340         ETH_P_MPLS_MC,
341 };
342
343 /*
344  * Locking shorthand.
345  */
346 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
347 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
348 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
349 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
350 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
351                                      ppp_recv_lock(ppp); } while (0)
352 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
353                                      ppp_xmit_unlock(ppp); } while (0)
354
355 /*
356  * /dev/ppp device routines.
357  * The /dev/ppp device is used by pppd to control the ppp unit.
358  * It supports the read, write, ioctl and poll functions.
359  * Open instances of /dev/ppp can be in one of three states:
360  * unattached, attached to a ppp unit, or attached to a ppp channel.
361  */
362 static int ppp_open(struct inode *inode, struct file *file)
363 {
364         cycle_kernel_lock();
365         /*
366          * This could (should?) be enforced by the permissions on /dev/ppp.
367          */
368         if (!capable(CAP_NET_ADMIN))
369                 return -EPERM;
370         return 0;
371 }
372
373 static int ppp_release(struct inode *unused, struct file *file)
374 {
375         struct ppp_file *pf = file->private_data;
376         struct ppp *ppp;
377
378         if (pf) {
379                 file->private_data = NULL;
380                 if (pf->kind == INTERFACE) {
381                         ppp = PF_TO_PPP(pf);
382                         if (file == ppp->owner)
383                                 ppp_shutdown_interface(ppp);
384                 }
385                 if (atomic_dec_and_test(&pf->refcnt)) {
386                         switch (pf->kind) {
387                         case INTERFACE:
388                                 ppp_destroy_interface(PF_TO_PPP(pf));
389                                 break;
390                         case CHANNEL:
391                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
392                                 break;
393                         }
394                 }
395         }
396         return 0;
397 }
398
399 static ssize_t ppp_read(struct file *file, char __user *buf,
400                         size_t count, loff_t *ppos)
401 {
402         struct ppp_file *pf = file->private_data;
403         DECLARE_WAITQUEUE(wait, current);
404         ssize_t ret;
405         struct sk_buff *skb = NULL;
406
407         ret = count;
408
409         if (!pf)
410                 return -ENXIO;
411         add_wait_queue(&pf->rwait, &wait);
412         for (;;) {
413                 set_current_state(TASK_INTERRUPTIBLE);
414                 skb = skb_dequeue(&pf->rq);
415                 if (skb)
416                         break;
417                 ret = 0;
418                 if (pf->dead)
419                         break;
420                 if (pf->kind == INTERFACE) {
421                         /*
422                          * Return 0 (EOF) on an interface that has no
423                          * channels connected, unless it is looping
424                          * network traffic (demand mode).
425                          */
426                         struct ppp *ppp = PF_TO_PPP(pf);
427                         if (ppp->n_channels == 0
428                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
429                                 break;
430                 }
431                 ret = -EAGAIN;
432                 if (file->f_flags & O_NONBLOCK)
433                         break;
434                 ret = -ERESTARTSYS;
435                 if (signal_pending(current))
436                         break;
437                 schedule();
438         }
439         set_current_state(TASK_RUNNING);
440         remove_wait_queue(&pf->rwait, &wait);
441
442         if (!skb)
443                 goto out;
444
445         ret = -EOVERFLOW;
446         if (skb->len > count)
447                 goto outf;
448         ret = -EFAULT;
449         if (copy_to_user(buf, skb->data, skb->len))
450                 goto outf;
451         ret = skb->len;
452
453  outf:
454         kfree_skb(skb);
455  out:
456         return ret;
457 }
458
459 static ssize_t ppp_write(struct file *file, const char __user *buf,
460                          size_t count, loff_t *ppos)
461 {
462         struct ppp_file *pf = file->private_data;
463         struct sk_buff *skb;
464         ssize_t ret;
465
466         if (!pf)
467                 return -ENXIO;
468         ret = -ENOMEM;
469         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
470         if (!skb)
471                 goto out;
472         skb_reserve(skb, pf->hdrlen);
473         ret = -EFAULT;
474         if (copy_from_user(skb_put(skb, count), buf, count)) {
475                 kfree_skb(skb);
476                 goto out;
477         }
478
479         skb_queue_tail(&pf->xq, skb);
480
481         switch (pf->kind) {
482         case INTERFACE:
483                 ppp_xmit_process(PF_TO_PPP(pf));
484                 break;
485         case CHANNEL:
486                 ppp_channel_push(PF_TO_CHANNEL(pf));
487                 break;
488         }
489
490         ret = count;
491
492  out:
493         return ret;
494 }
495
496 /* No kernel lock - fine */
497 static unsigned int ppp_poll(struct file *file, poll_table *wait)
498 {
499         struct ppp_file *pf = file->private_data;
500         unsigned int mask;
501
502         if (!pf)
503                 return 0;
504         poll_wait(file, &pf->rwait, wait);
505         mask = POLLOUT | POLLWRNORM;
506         if (skb_peek(&pf->rq))
507                 mask |= POLLIN | POLLRDNORM;
508         if (pf->dead)
509                 mask |= POLLHUP;
510         else if (pf->kind == INTERFACE) {
511                 /* see comment in ppp_read */
512                 struct ppp *ppp = PF_TO_PPP(pf);
513                 if (ppp->n_channels == 0
514                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
515                         mask |= POLLIN | POLLRDNORM;
516         }
517
518         return mask;
519 }
520
521 #ifdef CONFIG_PPP_FILTER
522 static int get_filter(void __user *arg, struct sock_filter **p)
523 {
524         struct sock_fprog uprog;
525         struct sock_filter *code = NULL;
526         int len, err;
527
528         if (copy_from_user(&uprog, arg, sizeof(uprog)))
529                 return -EFAULT;
530
531         if (!uprog.len) {
532                 *p = NULL;
533                 return 0;
534         }
535
536         len = uprog.len * sizeof(struct sock_filter);
537         code = kmalloc(len, GFP_KERNEL);
538         if (code == NULL)
539                 return -ENOMEM;
540
541         if (copy_from_user(code, uprog.filter, len)) {
542                 kfree(code);
543                 return -EFAULT;
544         }
545
546         err = sk_chk_filter(code, uprog.len);
547         if (err) {
548                 kfree(code);
549                 return err;
550         }
551
552         *p = code;
553         return uprog.len;
554 }
555 #endif /* CONFIG_PPP_FILTER */
556
557 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
558 {
559         struct ppp_file *pf = file->private_data;
560         struct ppp *ppp;
561         int err = -EFAULT, val, val2, i;
562         struct ppp_idle idle;
563         struct npioctl npi;
564         int unit, cflags;
565         struct slcompress *vj;
566         void __user *argp = (void __user *)arg;
567         int __user *p = argp;
568
569         if (!pf)
570                 return ppp_unattached_ioctl(current->nsproxy->net_ns,
571                                         pf, file, cmd, arg);
572
573         if (cmd == PPPIOCDETACH) {
574                 /*
575                  * We have to be careful here... if the file descriptor
576                  * has been dup'd, we could have another process in the
577                  * middle of a poll using the same file *, so we had
578                  * better not free the interface data structures -
579                  * instead we fail the ioctl.  Even in this case, we
580                  * shut down the interface if we are the owner of it.
581                  * Actually, we should get rid of PPPIOCDETACH, userland
582                  * (i.e. pppd) could achieve the same effect by closing
583                  * this fd and reopening /dev/ppp.
584                  */
585                 err = -EINVAL;
586                 lock_kernel();
587                 if (pf->kind == INTERFACE) {
588                         ppp = PF_TO_PPP(pf);
589                         if (file == ppp->owner)
590                                 ppp_shutdown_interface(ppp);
591                 }
592                 if (atomic_long_read(&file->f_count) <= 2) {
593                         ppp_release(NULL, file);
594                         err = 0;
595                 } else
596                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
597                                atomic_long_read(&file->f_count));
598                 unlock_kernel();
599                 return err;
600         }
601
602         if (pf->kind == CHANNEL) {
603                 struct channel *pch;
604                 struct ppp_channel *chan;
605
606                 lock_kernel();
607                 pch = PF_TO_CHANNEL(pf);
608
609                 switch (cmd) {
610                 case PPPIOCCONNECT:
611                         if (get_user(unit, p))
612                                 break;
613                         err = ppp_connect_channel(pch, unit);
614                         break;
615
616                 case PPPIOCDISCONN:
617                         err = ppp_disconnect_channel(pch);
618                         break;
619
620                 default:
621                         down_read(&pch->chan_sem);
622                         chan = pch->chan;
623                         err = -ENOTTY;
624                         if (chan && chan->ops->ioctl)
625                                 err = chan->ops->ioctl(chan, cmd, arg);
626                         up_read(&pch->chan_sem);
627                 }
628                 unlock_kernel();
629                 return err;
630         }
631
632         if (pf->kind != INTERFACE) {
633                 /* can't happen */
634                 printk(KERN_ERR "PPP: not interface or channel??\n");
635                 return -EINVAL;
636         }
637
638         lock_kernel();
639         ppp = PF_TO_PPP(pf);
640         switch (cmd) {
641         case PPPIOCSMRU:
642                 if (get_user(val, p))
643                         break;
644                 ppp->mru = val;
645                 err = 0;
646                 break;
647
648         case PPPIOCSFLAGS:
649                 if (get_user(val, p))
650                         break;
651                 ppp_lock(ppp);
652                 cflags = ppp->flags & ~val;
653                 ppp->flags = val & SC_FLAG_BITS;
654                 ppp_unlock(ppp);
655                 if (cflags & SC_CCP_OPEN)
656                         ppp_ccp_closed(ppp);
657                 err = 0;
658                 break;
659
660         case PPPIOCGFLAGS:
661                 val = ppp->flags | ppp->xstate | ppp->rstate;
662                 if (put_user(val, p))
663                         break;
664                 err = 0;
665                 break;
666
667         case PPPIOCSCOMPRESS:
668                 err = ppp_set_compress(ppp, arg);
669                 break;
670
671         case PPPIOCGUNIT:
672                 if (put_user(ppp->file.index, p))
673                         break;
674                 err = 0;
675                 break;
676
677         case PPPIOCSDEBUG:
678                 if (get_user(val, p))
679                         break;
680                 ppp->debug = val;
681                 err = 0;
682                 break;
683
684         case PPPIOCGDEBUG:
685                 if (put_user(ppp->debug, p))
686                         break;
687                 err = 0;
688                 break;
689
690         case PPPIOCGIDLE:
691                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
692                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
693                 if (copy_to_user(argp, &idle, sizeof(idle)))
694                         break;
695                 err = 0;
696                 break;
697
698         case PPPIOCSMAXCID:
699                 if (get_user(val, p))
700                         break;
701                 val2 = 15;
702                 if ((val >> 16) != 0) {
703                         val2 = val >> 16;
704                         val &= 0xffff;
705                 }
706                 vj = slhc_init(val2+1, val+1);
707                 if (!vj) {
708                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
709                         err = -ENOMEM;
710                         break;
711                 }
712                 ppp_lock(ppp);
713                 if (ppp->vj)
714                         slhc_free(ppp->vj);
715                 ppp->vj = vj;
716                 ppp_unlock(ppp);
717                 err = 0;
718                 break;
719
720         case PPPIOCGNPMODE:
721         case PPPIOCSNPMODE:
722                 if (copy_from_user(&npi, argp, sizeof(npi)))
723                         break;
724                 err = proto_to_npindex(npi.protocol);
725                 if (err < 0)
726                         break;
727                 i = err;
728                 if (cmd == PPPIOCGNPMODE) {
729                         err = -EFAULT;
730                         npi.mode = ppp->npmode[i];
731                         if (copy_to_user(argp, &npi, sizeof(npi)))
732                                 break;
733                 } else {
734                         ppp->npmode[i] = npi.mode;
735                         /* we may be able to transmit more packets now (??) */
736                         netif_wake_queue(ppp->dev);
737                 }
738                 err = 0;
739                 break;
740
741 #ifdef CONFIG_PPP_FILTER
742         case PPPIOCSPASS:
743         {
744                 struct sock_filter *code;
745                 err = get_filter(argp, &code);
746                 if (err >= 0) {
747                         ppp_lock(ppp);
748                         kfree(ppp->pass_filter);
749                         ppp->pass_filter = code;
750                         ppp->pass_len = err;
751                         ppp_unlock(ppp);
752                         err = 0;
753                 }
754                 break;
755         }
756         case PPPIOCSACTIVE:
757         {
758                 struct sock_filter *code;
759                 err = get_filter(argp, &code);
760                 if (err >= 0) {
761                         ppp_lock(ppp);
762                         kfree(ppp->active_filter);
763                         ppp->active_filter = code;
764                         ppp->active_len = err;
765                         ppp_unlock(ppp);
766                         err = 0;
767                 }
768                 break;
769         }
770 #endif /* CONFIG_PPP_FILTER */
771
772 #ifdef CONFIG_PPP_MULTILINK
773         case PPPIOCSMRRU:
774                 if (get_user(val, p))
775                         break;
776                 ppp_recv_lock(ppp);
777                 ppp->mrru = val;
778                 ppp_recv_unlock(ppp);
779                 err = 0;
780                 break;
781 #endif /* CONFIG_PPP_MULTILINK */
782
783         default:
784                 err = -ENOTTY;
785         }
786         unlock_kernel();
787         return err;
788 }
789
790 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
791                         struct file *file, unsigned int cmd, unsigned long arg)
792 {
793         int unit, err = -EFAULT;
794         struct ppp *ppp;
795         struct channel *chan;
796         struct ppp_net *pn;
797         int __user *p = (int __user *)arg;
798
799         lock_kernel();
800         switch (cmd) {
801         case PPPIOCNEWUNIT:
802                 /* Create a new ppp unit */
803                 if (get_user(unit, p))
804                         break;
805                 ppp = ppp_create_interface(net, unit, &err);
806                 if (!ppp)
807                         break;
808                 file->private_data = &ppp->file;
809                 ppp->owner = file;
810                 err = -EFAULT;
811                 if (put_user(ppp->file.index, p))
812                         break;
813                 err = 0;
814                 break;
815
816         case PPPIOCATTACH:
817                 /* Attach to an existing ppp unit */
818                 if (get_user(unit, p))
819                         break;
820                 err = -ENXIO;
821                 pn = ppp_pernet(net);
822                 mutex_lock(&pn->all_ppp_mutex);
823                 ppp = ppp_find_unit(pn, unit);
824                 if (ppp) {
825                         atomic_inc(&ppp->file.refcnt);
826                         file->private_data = &ppp->file;
827                         err = 0;
828                 }
829                 mutex_unlock(&pn->all_ppp_mutex);
830                 break;
831
832         case PPPIOCATTCHAN:
833                 if (get_user(unit, p))
834                         break;
835                 err = -ENXIO;
836                 pn = ppp_pernet(net);
837                 spin_lock_bh(&pn->all_channels_lock);
838                 chan = ppp_find_channel(pn, unit);
839                 if (chan) {
840                         atomic_inc(&chan->file.refcnt);
841                         file->private_data = &chan->file;
842                         err = 0;
843                 }
844                 spin_unlock_bh(&pn->all_channels_lock);
845                 break;
846
847         default:
848                 err = -ENOTTY;
849         }
850         unlock_kernel();
851         return err;
852 }
853
854 static const struct file_operations ppp_device_fops = {
855         .owner          = THIS_MODULE,
856         .read           = ppp_read,
857         .write          = ppp_write,
858         .poll           = ppp_poll,
859         .unlocked_ioctl = ppp_ioctl,
860         .open           = ppp_open,
861         .release        = ppp_release
862 };
863
864 static __net_init int ppp_init_net(struct net *net)
865 {
866         struct ppp_net *pn;
867         int err;
868
869         pn = kzalloc(sizeof(*pn), GFP_KERNEL);
870         if (!pn)
871                 return -ENOMEM;
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         err = net_assign_generic(net, ppp_net_id, pn);
882         if (err) {
883                 kfree(pn);
884                 return err;
885         }
886
887         return 0;
888 }
889
890 static __net_exit void ppp_exit_net(struct net *net)
891 {
892         struct ppp_net *pn;
893
894         pn = net_generic(net, ppp_net_id);
895         idr_destroy(&pn->units_idr);
896         /*
897          * if someone has cached our net then
898          * further net_generic call will return NULL
899          */
900         net_assign_generic(net, ppp_net_id, NULL);
901         kfree(pn);
902 }
903
904 static __net_initdata struct pernet_operations ppp_net_ops = {
905         .init = ppp_init_net,
906         .exit = ppp_exit_net,
907 };
908
909 #define PPP_MAJOR       108
910
911 /* Called at boot time if ppp is compiled into the kernel,
912    or at module load time (from init_module) if compiled as a module. */
913 static int __init ppp_init(void)
914 {
915         int err;
916
917         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
918
919         err = register_pernet_gen_device(&ppp_net_id, &ppp_net_ops);
920         if (err) {
921                 printk(KERN_ERR "failed to register PPP pernet device (%d)\n", err);
922                 goto out;
923         }
924
925         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
926         if (err) {
927                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
928                 goto out_net;
929         }
930
931         ppp_class = class_create(THIS_MODULE, "ppp");
932         if (IS_ERR(ppp_class)) {
933                 err = PTR_ERR(ppp_class);
934                 goto out_chrdev;
935         }
936
937         /* not a big deal if we fail here :-) */
938         device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
939
940         return 0;
941
942 out_chrdev:
943         unregister_chrdev(PPP_MAJOR, "ppp");
944 out_net:
945         unregister_pernet_gen_device(ppp_net_id, &ppp_net_ops);
946 out:
947         return err;
948 }
949
950 /*
951  * Network interface unit routines.
952  */
953 static int
954 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
955 {
956         struct ppp *ppp = netdev_priv(dev);
957         int npi, proto;
958         unsigned char *pp;
959
960         npi = ethertype_to_npindex(ntohs(skb->protocol));
961         if (npi < 0)
962                 goto outf;
963
964         /* Drop, accept or reject the packet */
965         switch (ppp->npmode[npi]) {
966         case NPMODE_PASS:
967                 break;
968         case NPMODE_QUEUE:
969                 /* it would be nice to have a way to tell the network
970                    system to queue this one up for later. */
971                 goto outf;
972         case NPMODE_DROP:
973         case NPMODE_ERROR:
974                 goto outf;
975         }
976
977         /* Put the 2-byte PPP protocol number on the front,
978            making sure there is room for the address and control fields. */
979         if (skb_cow_head(skb, PPP_HDRLEN))
980                 goto outf;
981
982         pp = skb_push(skb, 2);
983         proto = npindex_to_proto[npi];
984         pp[0] = proto >> 8;
985         pp[1] = proto;
986
987         netif_stop_queue(dev);
988         skb_queue_tail(&ppp->file.xq, skb);
989         ppp_xmit_process(ppp);
990         return 0;
991
992  outf:
993         kfree_skb(skb);
994         ++ppp->dev->stats.tx_dropped;
995         return 0;
996 }
997
998 static int
999 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
1000 {
1001         struct ppp *ppp = netdev_priv(dev);
1002         int err = -EFAULT;
1003         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
1004         struct ppp_stats stats;
1005         struct ppp_comp_stats cstats;
1006         char *vers;
1007
1008         switch (cmd) {
1009         case SIOCGPPPSTATS:
1010                 ppp_get_stats(ppp, &stats);
1011                 if (copy_to_user(addr, &stats, sizeof(stats)))
1012                         break;
1013                 err = 0;
1014                 break;
1015
1016         case SIOCGPPPCSTATS:
1017                 memset(&cstats, 0, sizeof(cstats));
1018                 if (ppp->xc_state)
1019                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
1020                 if (ppp->rc_state)
1021                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
1022                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
1023                         break;
1024                 err = 0;
1025                 break;
1026
1027         case SIOCGPPPVER:
1028                 vers = PPP_VERSION;
1029                 if (copy_to_user(addr, vers, strlen(vers) + 1))
1030                         break;
1031                 err = 0;
1032                 break;
1033
1034         default:
1035                 err = -EINVAL;
1036         }
1037
1038         return err;
1039 }
1040
1041 static const struct net_device_ops ppp_netdev_ops = {
1042         .ndo_start_xmit = ppp_start_xmit,
1043         .ndo_do_ioctl   = ppp_net_ioctl,
1044 };
1045
1046 static void ppp_setup(struct net_device *dev)
1047 {
1048         dev->netdev_ops = &ppp_netdev_ops;
1049         dev->hard_header_len = PPP_HDRLEN;
1050         dev->mtu = PPP_MTU;
1051         dev->addr_len = 0;
1052         dev->tx_queue_len = 3;
1053         dev->type = ARPHRD_PPP;
1054         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1055         dev->features |= NETIF_F_NETNS_LOCAL;
1056 }
1057
1058 /*
1059  * Transmit-side routines.
1060  */
1061
1062 /*
1063  * Called to do any work queued up on the transmit side
1064  * that can now be done.
1065  */
1066 static void
1067 ppp_xmit_process(struct ppp *ppp)
1068 {
1069         struct sk_buff *skb;
1070
1071         ppp_xmit_lock(ppp);
1072         if (!ppp->closing) {
1073                 ppp_push(ppp);
1074                 while (!ppp->xmit_pending
1075                        && (skb = skb_dequeue(&ppp->file.xq)))
1076                         ppp_send_frame(ppp, skb);
1077                 /* If there's no work left to do, tell the core net
1078                    code that we can accept some more. */
1079                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1080                         netif_wake_queue(ppp->dev);
1081         }
1082         ppp_xmit_unlock(ppp);
1083 }
1084
1085 static inline struct sk_buff *
1086 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1087 {
1088         struct sk_buff *new_skb;
1089         int len;
1090         int new_skb_size = ppp->dev->mtu +
1091                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1092         int compressor_skb_size = ppp->dev->mtu +
1093                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1094         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1095         if (!new_skb) {
1096                 if (net_ratelimit())
1097                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1098                 return NULL;
1099         }
1100         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1101                 skb_reserve(new_skb,
1102                             ppp->dev->hard_header_len - PPP_HDRLEN);
1103
1104         /* compressor still expects A/C bytes in hdr */
1105         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1106                                    new_skb->data, skb->len + 2,
1107                                    compressor_skb_size);
1108         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1109                 kfree_skb(skb);
1110                 skb = new_skb;
1111                 skb_put(skb, len);
1112                 skb_pull(skb, 2);       /* pull off A/C bytes */
1113         } else if (len == 0) {
1114                 /* didn't compress, or CCP not up yet */
1115                 kfree_skb(new_skb);
1116                 new_skb = skb;
1117         } else {
1118                 /*
1119                  * (len < 0)
1120                  * MPPE requires that we do not send unencrypted
1121                  * frames.  The compressor will return -1 if we
1122                  * should drop the frame.  We cannot simply test
1123                  * the compress_proto because MPPE and MPPC share
1124                  * the same number.
1125                  */
1126                 if (net_ratelimit())
1127                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1128                 kfree_skb(skb);
1129                 kfree_skb(new_skb);
1130                 new_skb = NULL;
1131         }
1132         return new_skb;
1133 }
1134
1135 /*
1136  * Compress and send a frame.
1137  * The caller should have locked the xmit path,
1138  * and xmit_pending should be 0.
1139  */
1140 static void
1141 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1142 {
1143         int proto = PPP_PROTO(skb);
1144         struct sk_buff *new_skb;
1145         int len;
1146         unsigned char *cp;
1147
1148         if (proto < 0x8000) {
1149 #ifdef CONFIG_PPP_FILTER
1150                 /* check if we should pass this packet */
1151                 /* the filter instructions are constructed assuming
1152                    a four-byte PPP header on each packet */
1153                 *skb_push(skb, 2) = 1;
1154                 if (ppp->pass_filter
1155                     && sk_run_filter(skb, ppp->pass_filter,
1156                                      ppp->pass_len) == 0) {
1157                         if (ppp->debug & 1)
1158                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1159                         kfree_skb(skb);
1160                         return;
1161                 }
1162                 /* if this packet passes the active filter, record the time */
1163                 if (!(ppp->active_filter
1164                       && sk_run_filter(skb, ppp->active_filter,
1165                                        ppp->active_len) == 0))
1166                         ppp->last_xmit = jiffies;
1167                 skb_pull(skb, 2);
1168 #else
1169                 /* for data packets, record the time */
1170                 ppp->last_xmit = jiffies;
1171 #endif /* CONFIG_PPP_FILTER */
1172         }
1173
1174         ++ppp->dev->stats.tx_packets;
1175         ppp->dev->stats.tx_bytes += skb->len - 2;
1176
1177         switch (proto) {
1178         case PPP_IP:
1179                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1180                         break;
1181                 /* try to do VJ TCP header compression */
1182                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1183                                     GFP_ATOMIC);
1184                 if (!new_skb) {
1185                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1186                         goto drop;
1187                 }
1188                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1189                 cp = skb->data + 2;
1190                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1191                                     new_skb->data + 2, &cp,
1192                                     !(ppp->flags & SC_NO_TCP_CCID));
1193                 if (cp == skb->data + 2) {
1194                         /* didn't compress */
1195                         kfree_skb(new_skb);
1196                 } else {
1197                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1198                                 proto = PPP_VJC_COMP;
1199                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1200                         } else {
1201                                 proto = PPP_VJC_UNCOMP;
1202                                 cp[0] = skb->data[2];
1203                         }
1204                         kfree_skb(skb);
1205                         skb = new_skb;
1206                         cp = skb_put(skb, len + 2);
1207                         cp[0] = 0;
1208                         cp[1] = proto;
1209                 }
1210                 break;
1211
1212         case PPP_CCP:
1213                 /* peek at outbound CCP frames */
1214                 ppp_ccp_peek(ppp, skb, 0);
1215                 break;
1216         }
1217
1218         /* try to do packet compression */
1219         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state
1220             && proto != PPP_LCP && proto != PPP_CCP) {
1221                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1222                         if (net_ratelimit())
1223                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1224                         goto drop;
1225                 }
1226                 skb = pad_compress_skb(ppp, skb);
1227                 if (!skb)
1228                         goto drop;
1229         }
1230
1231         /*
1232          * If we are waiting for traffic (demand dialling),
1233          * queue it up for pppd to receive.
1234          */
1235         if (ppp->flags & SC_LOOP_TRAFFIC) {
1236                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1237                         goto drop;
1238                 skb_queue_tail(&ppp->file.rq, skb);
1239                 wake_up_interruptible(&ppp->file.rwait);
1240                 return;
1241         }
1242
1243         ppp->xmit_pending = skb;
1244         ppp_push(ppp);
1245         return;
1246
1247  drop:
1248         if (skb)
1249                 kfree_skb(skb);
1250         ++ppp->dev->stats.tx_errors;
1251 }
1252
1253 /*
1254  * Try to send the frame in xmit_pending.
1255  * The caller should have the xmit path locked.
1256  */
1257 static void
1258 ppp_push(struct ppp *ppp)
1259 {
1260         struct list_head *list;
1261         struct channel *pch;
1262         struct sk_buff *skb = ppp->xmit_pending;
1263
1264         if (!skb)
1265                 return;
1266
1267         list = &ppp->channels;
1268         if (list_empty(list)) {
1269                 /* nowhere to send the packet, just drop it */
1270                 ppp->xmit_pending = NULL;
1271                 kfree_skb(skb);
1272                 return;
1273         }
1274
1275         if ((ppp->flags & SC_MULTILINK) == 0) {
1276                 /* not doing multilink: send it down the first channel */
1277                 list = list->next;
1278                 pch = list_entry(list, struct channel, clist);
1279
1280                 spin_lock_bh(&pch->downl);
1281                 if (pch->chan) {
1282                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1283                                 ppp->xmit_pending = NULL;
1284                 } else {
1285                         /* channel got unregistered */
1286                         kfree_skb(skb);
1287                         ppp->xmit_pending = NULL;
1288                 }
1289                 spin_unlock_bh(&pch->downl);
1290                 return;
1291         }
1292
1293 #ifdef CONFIG_PPP_MULTILINK
1294         /* Multilink: fragment the packet over as many links
1295            as can take the packet at the moment. */
1296         if (!ppp_mp_explode(ppp, skb))
1297                 return;
1298 #endif /* CONFIG_PPP_MULTILINK */
1299
1300         ppp->xmit_pending = NULL;
1301         kfree_skb(skb);
1302 }
1303
1304 #ifdef CONFIG_PPP_MULTILINK
1305 /*
1306  * Divide a packet to be transmitted into fragments and
1307  * send them out the individual links.
1308  */
1309 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1310 {
1311         int len, fragsize;
1312         int i, bits, hdrlen, mtu;
1313         int flen;
1314         int navail, nfree;
1315         int nbigger;
1316         unsigned char *p, *q;
1317         struct list_head *list;
1318         struct channel *pch;
1319         struct sk_buff *frag;
1320         struct ppp_channel *chan;
1321
1322         nfree = 0;      /* # channels which have no packet already queued */
1323         navail = 0;     /* total # of usable channels (not deregistered) */
1324         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1325         i = 0;
1326         list_for_each_entry(pch, &ppp->channels, clist) {
1327                 navail += pch->avail = (pch->chan != NULL);
1328                 if (pch->avail) {
1329                         if (skb_queue_empty(&pch->file.xq) ||
1330                             !pch->had_frag) {
1331                                 pch->avail = 2;
1332                                 ++nfree;
1333                         }
1334                         if (!pch->had_frag && i < ppp->nxchan)
1335                                 ppp->nxchan = i;
1336                 }
1337                 ++i;
1338         }
1339
1340         /*
1341          * Don't start sending this packet unless at least half of
1342          * the channels are free.  This gives much better TCP
1343          * performance if we have a lot of channels.
1344          */
1345         if (nfree == 0 || nfree < navail / 2)
1346                 return 0;       /* can't take now, leave it in xmit_pending */
1347
1348         /* Do protocol field compression (XXX this should be optional) */
1349         p = skb->data;
1350         len = skb->len;
1351         if (*p == 0) {
1352                 ++p;
1353                 --len;
1354         }
1355
1356         /*
1357          * Decide on fragment size.
1358          * We create a fragment for each free channel regardless of
1359          * how small they are (i.e. even 0 length) in order to minimize
1360          * the time that it will take to detect when a channel drops
1361          * a fragment.
1362          */
1363         fragsize = len;
1364         if (nfree > 1)
1365                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1366         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1367            except if nbigger==0, then they all get fragsize. */
1368         nbigger = len % nfree;
1369
1370         /* skip to the channel after the one we last used
1371            and start at that one */
1372         list = &ppp->channels;
1373         for (i = 0; i < ppp->nxchan; ++i) {
1374                 list = list->next;
1375                 if (list == &ppp->channels) {
1376                         i = 0;
1377                         break;
1378                 }
1379         }
1380
1381         /* create a fragment for each channel */
1382         bits = B;
1383         while (nfree > 0 || len > 0) {
1384                 list = list->next;
1385                 if (list == &ppp->channels) {
1386                         i = 0;
1387                         continue;
1388                 }
1389                 pch = list_entry(list, struct channel, clist);
1390                 ++i;
1391                 if (!pch->avail)
1392                         continue;
1393
1394                 /*
1395                  * Skip this channel if it has a fragment pending already and
1396                  * we haven't given a fragment to all of the free channels.
1397                  */
1398                 if (pch->avail == 1) {
1399                         if (nfree > 0)
1400                                 continue;
1401                 } else {
1402                         --nfree;
1403                         pch->avail = 1;
1404                 }
1405
1406                 /* check the channel's mtu and whether it is still attached. */
1407                 spin_lock_bh(&pch->downl);
1408                 if (pch->chan == NULL) {
1409                         /* can't use this channel, it's being deregistered */
1410                         spin_unlock_bh(&pch->downl);
1411                         pch->avail = 0;
1412                         if (--navail == 0)
1413                                 break;
1414                         continue;
1415                 }
1416
1417                 /*
1418                  * Create a fragment for this channel of
1419                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1420                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1421                  * MTU, so we use mtu = 2 + hdrlen.
1422                  */
1423                 if (fragsize > len)
1424                         fragsize = len;
1425                 flen = fragsize;
1426                 mtu = pch->chan->mtu + 2 - hdrlen;
1427                 if (mtu < 4)
1428                         mtu = 4;
1429                 if (flen > mtu)
1430                         flen = mtu;
1431                 if (flen == len && nfree == 0)
1432                         bits |= E;
1433                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1434                 if (!frag)
1435                         goto noskb;
1436                 q = skb_put(frag, flen + hdrlen);
1437
1438                 /* make the MP header */
1439                 q[0] = PPP_MP >> 8;
1440                 q[1] = PPP_MP;
1441                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1442                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1443                         q[3] = ppp->nxseq;
1444                 } else {
1445                         q[2] = bits;
1446                         q[3] = ppp->nxseq >> 16;
1447                         q[4] = ppp->nxseq >> 8;
1448                         q[5] = ppp->nxseq;
1449                 }
1450
1451                 /*
1452                  * Copy the data in.
1453                  * Unfortunately there is a bug in older versions of
1454                  * the Linux PPP multilink reconstruction code where it
1455                  * drops 0-length fragments.  Therefore we make sure the
1456                  * fragment has at least one byte of data.  Any bytes
1457                  * we add in this situation will end up as padding on the
1458                  * end of the reconstructed packet.
1459                  */
1460                 if (flen == 0)
1461                         *skb_put(frag, 1) = 0;
1462                 else
1463                         memcpy(q + hdrlen, p, flen);
1464
1465                 /* try to send it down the channel */
1466                 chan = pch->chan;
1467                 if (!skb_queue_empty(&pch->file.xq) ||
1468                     !chan->ops->start_xmit(chan, frag))
1469                         skb_queue_tail(&pch->file.xq, frag);
1470                 pch->had_frag = 1;
1471                 p += flen;
1472                 len -= flen;
1473                 ++ppp->nxseq;
1474                 bits = 0;
1475                 spin_unlock_bh(&pch->downl);
1476
1477                 if (--nbigger == 0 && fragsize > 0)
1478                         --fragsize;
1479         }
1480         ppp->nxchan = i;
1481
1482         return 1;
1483
1484  noskb:
1485         spin_unlock_bh(&pch->downl);
1486         if (ppp->debug & 1)
1487                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1488         ++ppp->dev->stats.tx_errors;
1489         ++ppp->nxseq;
1490         return 1;       /* abandon the frame */
1491 }
1492 #endif /* CONFIG_PPP_MULTILINK */
1493
1494 /*
1495  * Try to send data out on a channel.
1496  */
1497 static void
1498 ppp_channel_push(struct channel *pch)
1499 {
1500         struct sk_buff *skb;
1501         struct ppp *ppp;
1502
1503         spin_lock_bh(&pch->downl);
1504         if (pch->chan) {
1505                 while (!skb_queue_empty(&pch->file.xq)) {
1506                         skb = skb_dequeue(&pch->file.xq);
1507                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1508                                 /* put the packet back and try again later */
1509                                 skb_queue_head(&pch->file.xq, skb);
1510                                 break;
1511                         }
1512                 }
1513         } else {
1514                 /* channel got deregistered */
1515                 skb_queue_purge(&pch->file.xq);
1516         }
1517         spin_unlock_bh(&pch->downl);
1518         /* see if there is anything from the attached unit to be sent */
1519         if (skb_queue_empty(&pch->file.xq)) {
1520                 read_lock_bh(&pch->upl);
1521                 ppp = pch->ppp;
1522                 if (ppp)
1523                         ppp_xmit_process(ppp);
1524                 read_unlock_bh(&pch->upl);
1525         }
1526 }
1527
1528 /*
1529  * Receive-side routines.
1530  */
1531
1532 /* misuse a few fields of the skb for MP reconstruction */
1533 #define sequence        priority
1534 #define BEbits          cb[0]
1535
1536 static inline void
1537 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1538 {
1539         ppp_recv_lock(ppp);
1540         if (!ppp->closing)
1541                 ppp_receive_frame(ppp, skb, pch);
1542         else
1543                 kfree_skb(skb);
1544         ppp_recv_unlock(ppp);
1545 }
1546
1547 void
1548 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1549 {
1550         struct channel *pch = chan->ppp;
1551         int proto;
1552
1553         if (!pch || skb->len == 0) {
1554                 kfree_skb(skb);
1555                 return;
1556         }
1557
1558         proto = PPP_PROTO(skb);
1559         read_lock_bh(&pch->upl);
1560         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1561                 /* put it on the channel queue */
1562                 skb_queue_tail(&pch->file.rq, skb);
1563                 /* drop old frames if queue too long */
1564                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1565                        && (skb = skb_dequeue(&pch->file.rq)))
1566                         kfree_skb(skb);
1567                 wake_up_interruptible(&pch->file.rwait);
1568         } else {
1569                 ppp_do_recv(pch->ppp, skb, pch);
1570         }
1571         read_unlock_bh(&pch->upl);
1572 }
1573
1574 /* Put a 0-length skb in the receive queue as an error indication */
1575 void
1576 ppp_input_error(struct ppp_channel *chan, int code)
1577 {
1578         struct channel *pch = chan->ppp;
1579         struct sk_buff *skb;
1580
1581         if (!pch)
1582                 return;
1583
1584         read_lock_bh(&pch->upl);
1585         if (pch->ppp) {
1586                 skb = alloc_skb(0, GFP_ATOMIC);
1587                 if (skb) {
1588                         skb->len = 0;           /* probably unnecessary */
1589                         skb->cb[0] = code;
1590                         ppp_do_recv(pch->ppp, skb, pch);
1591                 }
1592         }
1593         read_unlock_bh(&pch->upl);
1594 }
1595
1596 /*
1597  * We come in here to process a received frame.
1598  * The receive side of the ppp unit is locked.
1599  */
1600 static void
1601 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1602 {
1603         if (pskb_may_pull(skb, 2)) {
1604 #ifdef CONFIG_PPP_MULTILINK
1605                 /* XXX do channel-level decompression here */
1606                 if (PPP_PROTO(skb) == PPP_MP)
1607                         ppp_receive_mp_frame(ppp, skb, pch);
1608                 else
1609 #endif /* CONFIG_PPP_MULTILINK */
1610                         ppp_receive_nonmp_frame(ppp, skb);
1611                 return;
1612         }
1613
1614         if (skb->len > 0)
1615                 /* note: a 0-length skb is used as an error indication */
1616                 ++ppp->dev->stats.rx_length_errors;
1617
1618         kfree_skb(skb);
1619         ppp_receive_error(ppp);
1620 }
1621
1622 static void
1623 ppp_receive_error(struct ppp *ppp)
1624 {
1625         ++ppp->dev->stats.rx_errors;
1626         if (ppp->vj)
1627                 slhc_toss(ppp->vj);
1628 }
1629
1630 static void
1631 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1632 {
1633         struct sk_buff *ns;
1634         int proto, len, npi;
1635
1636         /*
1637          * Decompress the frame, if compressed.
1638          * Note that some decompressors need to see uncompressed frames
1639          * that come in as well as compressed frames.
1640          */
1641         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)
1642             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1643                 skb = ppp_decompress_frame(ppp, skb);
1644
1645         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1646                 goto err;
1647
1648         proto = PPP_PROTO(skb);
1649         switch (proto) {
1650         case PPP_VJC_COMP:
1651                 /* decompress VJ compressed packets */
1652                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1653                         goto err;
1654
1655                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1656                         /* copy to a new sk_buff with more tailroom */
1657                         ns = dev_alloc_skb(skb->len + 128);
1658                         if (!ns) {
1659                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1660                                 goto err;
1661                         }
1662                         skb_reserve(ns, 2);
1663                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1664                         kfree_skb(skb);
1665                         skb = ns;
1666                 }
1667                 else
1668                         skb->ip_summed = CHECKSUM_NONE;
1669
1670                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1671                 if (len <= 0) {
1672                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1673                         goto err;
1674                 }
1675                 len += 2;
1676                 if (len > skb->len)
1677                         skb_put(skb, len - skb->len);
1678                 else if (len < skb->len)
1679                         skb_trim(skb, len);
1680                 proto = PPP_IP;
1681                 break;
1682
1683         case PPP_VJC_UNCOMP:
1684                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1685                         goto err;
1686
1687                 /* Until we fix the decompressor need to make sure
1688                  * data portion is linear.
1689                  */
1690                 if (!pskb_may_pull(skb, skb->len))
1691                         goto err;
1692
1693                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1694                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1695                         goto err;
1696                 }
1697                 proto = PPP_IP;
1698                 break;
1699
1700         case PPP_CCP:
1701                 ppp_ccp_peek(ppp, skb, 1);
1702                 break;
1703         }
1704
1705         ++ppp->dev->stats.rx_packets;
1706         ppp->dev->stats.rx_bytes += skb->len - 2;
1707
1708         npi = proto_to_npindex(proto);
1709         if (npi < 0) {
1710                 /* control or unknown frame - pass it to pppd */
1711                 skb_queue_tail(&ppp->file.rq, skb);
1712                 /* limit queue length by dropping old frames */
1713                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1714                        && (skb = skb_dequeue(&ppp->file.rq)))
1715                         kfree_skb(skb);
1716                 /* wake up any process polling or blocking on read */
1717                 wake_up_interruptible(&ppp->file.rwait);
1718
1719         } else {
1720                 /* network protocol frame - give it to the kernel */
1721
1722 #ifdef CONFIG_PPP_FILTER
1723                 /* check if the packet passes the pass and active filters */
1724                 /* the filter instructions are constructed assuming
1725                    a four-byte PPP header on each packet */
1726                 if (ppp->pass_filter || ppp->active_filter) {
1727                         if (skb_cloned(skb) &&
1728                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1729                                 goto err;
1730
1731                         *skb_push(skb, 2) = 0;
1732                         if (ppp->pass_filter
1733                             && sk_run_filter(skb, ppp->pass_filter,
1734                                              ppp->pass_len) == 0) {
1735                                 if (ppp->debug & 1)
1736                                         printk(KERN_DEBUG "PPP: inbound frame "
1737                                                "not passed\n");
1738                                 kfree_skb(skb);
1739                                 return;
1740                         }
1741                         if (!(ppp->active_filter
1742                               && sk_run_filter(skb, ppp->active_filter,
1743                                                ppp->active_len) == 0))
1744                                 ppp->last_recv = jiffies;
1745                         __skb_pull(skb, 2);
1746                 } else
1747 #endif /* CONFIG_PPP_FILTER */
1748                         ppp->last_recv = jiffies;
1749
1750                 if ((ppp->dev->flags & IFF_UP) == 0
1751                     || ppp->npmode[npi] != NPMODE_PASS) {
1752                         kfree_skb(skb);
1753                 } else {
1754                         /* chop off protocol */
1755                         skb_pull_rcsum(skb, 2);
1756                         skb->dev = ppp->dev;
1757                         skb->protocol = htons(npindex_to_ethertype[npi]);
1758                         skb_reset_mac_header(skb);
1759                         netif_rx(skb);
1760                 }
1761         }
1762         return;
1763
1764  err:
1765         kfree_skb(skb);
1766         ppp_receive_error(ppp);
1767 }
1768
1769 static struct sk_buff *
1770 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1771 {
1772         int proto = PPP_PROTO(skb);
1773         struct sk_buff *ns;
1774         int len;
1775
1776         /* Until we fix all the decompressor's need to make sure
1777          * data portion is linear.
1778          */
1779         if (!pskb_may_pull(skb, skb->len))
1780                 goto err;
1781
1782         if (proto == PPP_COMP) {
1783                 int obuff_size;
1784
1785                 switch(ppp->rcomp->compress_proto) {
1786                 case CI_MPPE:
1787                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1788                         break;
1789                 default:
1790                         obuff_size = ppp->mru + PPP_HDRLEN;
1791                         break;
1792                 }
1793
1794                 ns = dev_alloc_skb(obuff_size);
1795                 if (!ns) {
1796                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1797                         goto err;
1798                 }
1799                 /* the decompressor still expects the A/C bytes in the hdr */
1800                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1801                                 skb->len + 2, ns->data, obuff_size);
1802                 if (len < 0) {
1803                         /* Pass the compressed frame to pppd as an
1804                            error indication. */
1805                         if (len == DECOMP_FATALERROR)
1806                                 ppp->rstate |= SC_DC_FERROR;
1807                         kfree_skb(ns);
1808                         goto err;
1809                 }
1810
1811                 kfree_skb(skb);
1812                 skb = ns;
1813                 skb_put(skb, len);
1814                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1815
1816         } else {
1817                 /* Uncompressed frame - pass to decompressor so it
1818                    can update its dictionary if necessary. */
1819                 if (ppp->rcomp->incomp)
1820                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1821                                            skb->len + 2);
1822         }
1823
1824         return skb;
1825
1826  err:
1827         ppp->rstate |= SC_DC_ERROR;
1828         ppp_receive_error(ppp);
1829         return skb;
1830 }
1831
1832 #ifdef CONFIG_PPP_MULTILINK
1833 /*
1834  * Receive a multilink frame.
1835  * We put it on the reconstruction queue and then pull off
1836  * as many completed frames as we can.
1837  */
1838 static void
1839 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1840 {
1841         u32 mask, seq;
1842         struct channel *ch;
1843         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1844
1845         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1846                 goto err;               /* no good, throw it away */
1847
1848         /* Decode sequence number and begin/end bits */
1849         if (ppp->flags & SC_MP_SHORTSEQ) {
1850                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1851                 mask = 0xfff;
1852         } else {
1853                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1854                 mask = 0xffffff;
1855         }
1856         skb->BEbits = skb->data[2];
1857         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1858
1859         /*
1860          * Do protocol ID decompression on the first fragment of each packet.
1861          */
1862         if ((skb->BEbits & B) && (skb->data[0] & 1))
1863                 *skb_push(skb, 1) = 0;
1864
1865         /*
1866          * Expand sequence number to 32 bits, making it as close
1867          * as possible to ppp->minseq.
1868          */
1869         seq |= ppp->minseq & ~mask;
1870         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1871                 seq += mask + 1;
1872         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1873                 seq -= mask + 1;        /* should never happen */
1874         skb->sequence = seq;
1875         pch->lastseq = seq;
1876
1877         /*
1878          * If this packet comes before the next one we were expecting,
1879          * drop it.
1880          */
1881         if (seq_before(seq, ppp->nextseq)) {
1882                 kfree_skb(skb);
1883                 ++ppp->dev->stats.rx_dropped;
1884                 ppp_receive_error(ppp);
1885                 return;
1886         }
1887
1888         /*
1889          * Reevaluate minseq, the minimum over all channels of the
1890          * last sequence number received on each channel.  Because of
1891          * the increasing sequence number rule, we know that any fragment
1892          * before `minseq' which hasn't arrived is never going to arrive.
1893          * The list of channels can't change because we have the receive
1894          * side of the ppp unit locked.
1895          */
1896         list_for_each_entry(ch, &ppp->channels, clist) {
1897                 if (seq_before(ch->lastseq, seq))
1898                         seq = ch->lastseq;
1899         }
1900         if (seq_before(ppp->minseq, seq))
1901                 ppp->minseq = seq;
1902
1903         /* Put the fragment on the reconstruction queue */
1904         ppp_mp_insert(ppp, skb);
1905
1906         /* If the queue is getting long, don't wait any longer for packets
1907            before the start of the queue. */
1908         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
1909                 struct sk_buff *skb = skb_peek(&ppp->mrq);
1910                 if (seq_before(ppp->minseq, skb->sequence))
1911                         ppp->minseq = skb->sequence;
1912         }
1913
1914         /* Pull completed packets off the queue and receive them. */
1915         while ((skb = ppp_mp_reconstruct(ppp)))
1916                 ppp_receive_nonmp_frame(ppp, skb);
1917
1918         return;
1919
1920  err:
1921         kfree_skb(skb);
1922         ppp_receive_error(ppp);
1923 }
1924
1925 /*
1926  * Insert a fragment on the MP reconstruction queue.
1927  * The queue is ordered by increasing sequence number.
1928  */
1929 static void
1930 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1931 {
1932         struct sk_buff *p;
1933         struct sk_buff_head *list = &ppp->mrq;
1934         u32 seq = skb->sequence;
1935
1936         /* N.B. we don't need to lock the list lock because we have the
1937            ppp unit receive-side lock. */
1938         skb_queue_walk(list, p) {
1939                 if (seq_before(seq, p->sequence))
1940                         break;
1941         }
1942         __skb_queue_before(list, p, skb);
1943 }
1944
1945 /*
1946  * Reconstruct a packet from the MP fragment queue.
1947  * We go through increasing sequence numbers until we find a
1948  * complete packet, or we get to the sequence number for a fragment
1949  * which hasn't arrived but might still do so.
1950  */
1951 static struct sk_buff *
1952 ppp_mp_reconstruct(struct ppp *ppp)
1953 {
1954         u32 seq = ppp->nextseq;
1955         u32 minseq = ppp->minseq;
1956         struct sk_buff_head *list = &ppp->mrq;
1957         struct sk_buff *p, *next;
1958         struct sk_buff *head, *tail;
1959         struct sk_buff *skb = NULL;
1960         int lost = 0, len = 0;
1961
1962         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1963                 return NULL;
1964         head = list->next;
1965         tail = NULL;
1966         for (p = head; p != (struct sk_buff *) list; p = next) {
1967                 next = p->next;
1968                 if (seq_before(p->sequence, seq)) {
1969                         /* this can't happen, anyway ignore the skb */
1970                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1971                                p->sequence, seq);
1972                         head = next;
1973                         continue;
1974                 }
1975                 if (p->sequence != seq) {
1976                         /* Fragment `seq' is missing.  If it is after
1977                            minseq, it might arrive later, so stop here. */
1978                         if (seq_after(seq, minseq))
1979                                 break;
1980                         /* Fragment `seq' is lost, keep going. */
1981                         lost = 1;
1982                         seq = seq_before(minseq, p->sequence)?
1983                                 minseq + 1: p->sequence;
1984                         next = p;
1985                         continue;
1986                 }
1987
1988                 /*
1989                  * At this point we know that all the fragments from
1990                  * ppp->nextseq to seq are either present or lost.
1991                  * Also, there are no complete packets in the queue
1992                  * that have no missing fragments and end before this
1993                  * fragment.
1994                  */
1995
1996                 /* B bit set indicates this fragment starts a packet */
1997                 if (p->BEbits & B) {
1998                         head = p;
1999                         lost = 0;
2000                         len = 0;
2001                 }
2002
2003                 len += p->len;
2004
2005                 /* Got a complete packet yet? */
2006                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
2007                         if (len > ppp->mrru + 2) {
2008                                 ++ppp->dev->stats.rx_length_errors;
2009                                 printk(KERN_DEBUG "PPP: reconstructed packet"
2010                                        " is too long (%d)\n", len);
2011                         } else if (p == head) {
2012                                 /* fragment is complete packet - reuse skb */
2013                                 tail = p;
2014                                 skb = skb_get(p);
2015                                 break;
2016                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
2017                                 ++ppp->dev->stats.rx_missed_errors;
2018                                 printk(KERN_DEBUG "PPP: no memory for "
2019                                        "reconstructed packet");
2020                         } else {
2021                                 tail = p;
2022                                 break;
2023                         }
2024                         ppp->nextseq = seq + 1;
2025                 }
2026
2027                 /*
2028                  * If this is the ending fragment of a packet,
2029                  * and we haven't found a complete valid packet yet,
2030                  * we can discard up to and including this fragment.
2031                  */
2032                 if (p->BEbits & E)
2033                         head = next;
2034
2035                 ++seq;
2036         }
2037
2038         /* If we have a complete packet, copy it all into one skb. */
2039         if (tail != NULL) {
2040                 /* If we have discarded any fragments,
2041                    signal a receive error. */
2042                 if (head->sequence != ppp->nextseq) {
2043                         if (ppp->debug & 1)
2044                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
2045                                        ppp->nextseq, head->sequence-1);
2046                         ++ppp->dev->stats.rx_dropped;
2047                         ppp_receive_error(ppp);
2048                 }
2049
2050                 if (head != tail)
2051                         /* copy to a single skb */
2052                         for (p = head; p != tail->next; p = p->next)
2053                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
2054                 ppp->nextseq = tail->sequence + 1;
2055                 head = tail->next;
2056         }
2057
2058         /* Discard all the skbuffs that we have copied the data out of
2059            or that we can't use. */
2060         while ((p = list->next) != head) {
2061                 __skb_unlink(p, list);
2062                 kfree_skb(p);
2063         }
2064
2065         return skb;
2066 }
2067 #endif /* CONFIG_PPP_MULTILINK */
2068
2069 /*
2070  * Channel interface.
2071  */
2072
2073 /* Create a new, unattached ppp channel. */
2074 int ppp_register_channel(struct ppp_channel *chan)
2075 {
2076         return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2077 }
2078
2079 /* Create a new, unattached ppp channel for specified net. */
2080 int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2081 {
2082         struct channel *pch;
2083         struct ppp_net *pn;
2084
2085         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2086         if (!pch)
2087                 return -ENOMEM;
2088
2089         pn = ppp_pernet(net);
2090
2091         pch->ppp = NULL;
2092         pch->chan = chan;
2093         pch->chan_net = net;
2094         chan->ppp = pch;
2095         init_ppp_file(&pch->file, CHANNEL);
2096         pch->file.hdrlen = chan->hdrlen;
2097 #ifdef CONFIG_PPP_MULTILINK
2098         pch->lastseq = -1;
2099 #endif /* CONFIG_PPP_MULTILINK */
2100         init_rwsem(&pch->chan_sem);
2101         spin_lock_init(&pch->downl);
2102         rwlock_init(&pch->upl);
2103
2104         spin_lock_bh(&pn->all_channels_lock);
2105         pch->file.index = ++pn->last_channel_index;
2106         list_add(&pch->list, &pn->new_channels);
2107         atomic_inc(&channel_count);
2108         spin_unlock_bh(&pn->all_channels_lock);
2109
2110         return 0;
2111 }
2112
2113 /*
2114  * Return the index of a channel.
2115  */
2116 int ppp_channel_index(struct ppp_channel *chan)
2117 {
2118         struct channel *pch = chan->ppp;
2119
2120         if (pch)
2121                 return pch->file.index;
2122         return -1;
2123 }
2124
2125 /*
2126  * Return the PPP unit number to which a channel is connected.
2127  */
2128 int ppp_unit_number(struct ppp_channel *chan)
2129 {
2130         struct channel *pch = chan->ppp;
2131         int unit = -1;
2132
2133         if (pch) {
2134                 read_lock_bh(&pch->upl);
2135                 if (pch->ppp)
2136                         unit = pch->ppp->file.index;
2137                 read_unlock_bh(&pch->upl);
2138         }
2139         return unit;
2140 }
2141
2142 /*
2143  * Disconnect a channel from the generic layer.
2144  * This must be called in process context.
2145  */
2146 void
2147 ppp_unregister_channel(struct ppp_channel *chan)
2148 {
2149         struct channel *pch = chan->ppp;
2150         struct ppp_net *pn;
2151
2152         if (!pch)
2153                 return;         /* should never happen */
2154
2155         chan->ppp = NULL;
2156
2157         /*
2158          * This ensures that we have returned from any calls into the
2159          * the channel's start_xmit or ioctl routine before we proceed.
2160          */
2161         down_write(&pch->chan_sem);
2162         spin_lock_bh(&pch->downl);
2163         pch->chan = NULL;
2164         spin_unlock_bh(&pch->downl);
2165         up_write(&pch->chan_sem);
2166         ppp_disconnect_channel(pch);
2167
2168         pn = ppp_pernet(pch->chan_net);
2169         spin_lock_bh(&pn->all_channels_lock);
2170         list_del(&pch->list);
2171         spin_unlock_bh(&pn->all_channels_lock);
2172
2173         pch->file.dead = 1;
2174         wake_up_interruptible(&pch->file.rwait);
2175         if (atomic_dec_and_test(&pch->file.refcnt))
2176                 ppp_destroy_channel(pch);
2177 }
2178
2179 /*
2180  * Callback from a channel when it can accept more to transmit.
2181  * This should be called at BH/softirq level, not interrupt level.
2182  */
2183 void
2184 ppp_output_wakeup(struct ppp_channel *chan)
2185 {
2186         struct channel *pch = chan->ppp;
2187
2188         if (!pch)
2189                 return;
2190         ppp_channel_push(pch);
2191 }
2192
2193 /*
2194  * Compression control.
2195  */
2196
2197 /* Process the PPPIOCSCOMPRESS ioctl. */
2198 static int
2199 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2200 {
2201         int err;
2202         struct compressor *cp, *ocomp;
2203         struct ppp_option_data data;
2204         void *state, *ostate;
2205         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2206
2207         err = -EFAULT;
2208         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2209             || (data.length <= CCP_MAX_OPTION_LENGTH
2210                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2211                 goto out;
2212         err = -EINVAL;
2213         if (data.length > CCP_MAX_OPTION_LENGTH
2214             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2215                 goto out;
2216
2217         cp = try_then_request_module(
2218                 find_compressor(ccp_option[0]),
2219                 "ppp-compress-%d", ccp_option[0]);
2220         if (!cp)
2221                 goto out;
2222
2223         err = -ENOBUFS;
2224         if (data.transmit) {
2225                 state = cp->comp_alloc(ccp_option, data.length);
2226                 if (state) {
2227                         ppp_xmit_lock(ppp);
2228                         ppp->xstate &= ~SC_COMP_RUN;
2229                         ocomp = ppp->xcomp;
2230                         ostate = ppp->xc_state;
2231                         ppp->xcomp = cp;
2232                         ppp->xc_state = state;
2233                         ppp_xmit_unlock(ppp);
2234                         if (ostate) {
2235                                 ocomp->comp_free(ostate);
2236                                 module_put(ocomp->owner);
2237                         }
2238                         err = 0;
2239                 } else
2240                         module_put(cp->owner);
2241
2242         } else {
2243                 state = cp->decomp_alloc(ccp_option, data.length);
2244                 if (state) {
2245                         ppp_recv_lock(ppp);
2246                         ppp->rstate &= ~SC_DECOMP_RUN;
2247                         ocomp = ppp->rcomp;
2248                         ostate = ppp->rc_state;
2249                         ppp->rcomp = cp;
2250                         ppp->rc_state = state;
2251                         ppp_recv_unlock(ppp);
2252                         if (ostate) {
2253                                 ocomp->decomp_free(ostate);
2254                                 module_put(ocomp->owner);
2255                         }
2256                         err = 0;
2257                 } else
2258                         module_put(cp->owner);
2259         }
2260
2261  out:
2262         return err;
2263 }
2264
2265 /*
2266  * Look at a CCP packet and update our state accordingly.
2267  * We assume the caller has the xmit or recv path locked.
2268  */
2269 static void
2270 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2271 {
2272         unsigned char *dp;
2273         int len;
2274
2275         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2276                 return; /* no header */
2277         dp = skb->data + 2;
2278
2279         switch (CCP_CODE(dp)) {
2280         case CCP_CONFREQ:
2281
2282                 /* A ConfReq starts negotiation of compression
2283                  * in one direction of transmission,
2284                  * and hence brings it down...but which way?
2285                  *
2286                  * Remember:
2287                  * A ConfReq indicates what the sender would like to receive
2288                  */
2289                 if(inbound)
2290                         /* He is proposing what I should send */
2291                         ppp->xstate &= ~SC_COMP_RUN;
2292                 else
2293                         /* I am proposing to what he should send */
2294                         ppp->rstate &= ~SC_DECOMP_RUN;
2295
2296                 break;
2297
2298         case CCP_TERMREQ:
2299         case CCP_TERMACK:
2300                 /*
2301                  * CCP is going down, both directions of transmission
2302                  */
2303                 ppp->rstate &= ~SC_DECOMP_RUN;
2304                 ppp->xstate &= ~SC_COMP_RUN;
2305                 break;
2306
2307         case CCP_CONFACK:
2308                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2309                         break;
2310                 len = CCP_LENGTH(dp);
2311                 if (!pskb_may_pull(skb, len + 2))
2312                         return;         /* too short */
2313                 dp += CCP_HDRLEN;
2314                 len -= CCP_HDRLEN;
2315                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2316                         break;
2317                 if (inbound) {
2318                         /* we will start receiving compressed packets */
2319                         if (!ppp->rc_state)
2320                                 break;
2321                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2322                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2323                                 ppp->rstate |= SC_DECOMP_RUN;
2324                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2325                         }
2326                 } else {
2327                         /* we will soon start sending compressed packets */
2328                         if (!ppp->xc_state)
2329                                 break;
2330                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2331                                         ppp->file.index, 0, ppp->debug))
2332                                 ppp->xstate |= SC_COMP_RUN;
2333                 }
2334                 break;
2335
2336         case CCP_RESETACK:
2337                 /* reset the [de]compressor */
2338                 if ((ppp->flags & SC_CCP_UP) == 0)
2339                         break;
2340                 if (inbound) {
2341                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2342                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2343                                 ppp->rstate &= ~SC_DC_ERROR;
2344                         }
2345                 } else {
2346                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2347                                 ppp->xcomp->comp_reset(ppp->xc_state);
2348                 }
2349                 break;
2350         }
2351 }
2352
2353 /* Free up compression resources. */
2354 static void
2355 ppp_ccp_closed(struct ppp *ppp)
2356 {
2357         void *xstate, *rstate;
2358         struct compressor *xcomp, *rcomp;
2359
2360         ppp_lock(ppp);
2361         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2362         ppp->xstate = 0;
2363         xcomp = ppp->xcomp;
2364         xstate = ppp->xc_state;
2365         ppp->xc_state = NULL;
2366         ppp->rstate = 0;
2367         rcomp = ppp->rcomp;
2368         rstate = ppp->rc_state;
2369         ppp->rc_state = NULL;
2370         ppp_unlock(ppp);
2371
2372         if (xstate) {
2373                 xcomp->comp_free(xstate);
2374                 module_put(xcomp->owner);
2375         }
2376         if (rstate) {
2377                 rcomp->decomp_free(rstate);
2378                 module_put(rcomp->owner);
2379         }
2380 }
2381
2382 /* List of compressors. */
2383 static LIST_HEAD(compressor_list);
2384 static DEFINE_SPINLOCK(compressor_list_lock);
2385
2386 struct compressor_entry {
2387         struct list_head list;
2388         struct compressor *comp;
2389 };
2390
2391 static struct compressor_entry *
2392 find_comp_entry(int proto)
2393 {
2394         struct compressor_entry *ce;
2395
2396         list_for_each_entry(ce, &compressor_list, list) {
2397                 if (ce->comp->compress_proto == proto)
2398                         return ce;
2399         }
2400         return NULL;
2401 }
2402
2403 /* Register a compressor */
2404 int
2405 ppp_register_compressor(struct compressor *cp)
2406 {
2407         struct compressor_entry *ce;
2408         int ret;
2409         spin_lock(&compressor_list_lock);
2410         ret = -EEXIST;
2411         if (find_comp_entry(cp->compress_proto))
2412                 goto out;
2413         ret = -ENOMEM;
2414         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2415         if (!ce)
2416                 goto out;
2417         ret = 0;
2418         ce->comp = cp;
2419         list_add(&ce->list, &compressor_list);
2420  out:
2421         spin_unlock(&compressor_list_lock);
2422         return ret;
2423 }
2424
2425 /* Unregister a compressor */
2426 void
2427 ppp_unregister_compressor(struct compressor *cp)
2428 {
2429         struct compressor_entry *ce;
2430
2431         spin_lock(&compressor_list_lock);
2432         ce = find_comp_entry(cp->compress_proto);
2433         if (ce && ce->comp == cp) {
2434                 list_del(&ce->list);
2435                 kfree(ce);
2436         }
2437         spin_unlock(&compressor_list_lock);
2438 }
2439
2440 /* Find a compressor. */
2441 static struct compressor *
2442 find_compressor(int type)
2443 {
2444         struct compressor_entry *ce;
2445         struct compressor *cp = NULL;
2446
2447         spin_lock(&compressor_list_lock);
2448         ce = find_comp_entry(type);
2449         if (ce) {
2450                 cp = ce->comp;
2451                 if (!try_module_get(cp->owner))
2452                         cp = NULL;
2453         }
2454         spin_unlock(&compressor_list_lock);
2455         return cp;
2456 }
2457
2458 /*
2459  * Miscelleneous stuff.
2460  */
2461
2462 static void
2463 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2464 {
2465         struct slcompress *vj = ppp->vj;
2466
2467         memset(st, 0, sizeof(*st));
2468         st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
2469         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2470         st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
2471         st->p.ppp_opackets = ppp->dev->stats.tx_packets;
2472         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2473         st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
2474         if (!vj)
2475                 return;
2476         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2477         st->vj.vjs_compressed = vj->sls_o_compressed;
2478         st->vj.vjs_searches = vj->sls_o_searches;
2479         st->vj.vjs_misses = vj->sls_o_misses;
2480         st->vj.vjs_errorin = vj->sls_i_error;
2481         st->vj.vjs_tossed = vj->sls_i_tossed;
2482         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2483         st->vj.vjs_compressedin = vj->sls_i_compressed;
2484 }
2485
2486 /*
2487  * Stuff for handling the lists of ppp units and channels
2488  * and for initialization.
2489  */
2490
2491 /*
2492  * Create a new ppp interface unit.  Fails if it can't allocate memory
2493  * or if there is already a unit with the requested number.
2494  * unit == -1 means allocate a new number.
2495  */
2496 static struct ppp *
2497 ppp_create_interface(struct net *net, int unit, int *retp)
2498 {
2499         struct ppp *ppp;
2500         struct ppp_net *pn;
2501         struct net_device *dev = NULL;
2502         int ret = -ENOMEM;
2503         int i;
2504
2505         dev = alloc_netdev(sizeof(struct ppp), "", ppp_setup);
2506         if (!dev)
2507                 goto out1;
2508
2509         pn = ppp_pernet(net);
2510
2511         ppp = netdev_priv(dev);
2512         ppp->dev = dev;
2513         ppp->mru = PPP_MRU;
2514         init_ppp_file(&ppp->file, INTERFACE);
2515         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2516         for (i = 0; i < NUM_NP; ++i)
2517                 ppp->npmode[i] = NPMODE_PASS;
2518         INIT_LIST_HEAD(&ppp->channels);
2519         spin_lock_init(&ppp->rlock);
2520         spin_lock_init(&ppp->wlock);
2521 #ifdef CONFIG_PPP_MULTILINK
2522         ppp->minseq = -1;
2523         skb_queue_head_init(&ppp->mrq);
2524 #endif /* CONFIG_PPP_MULTILINK */
2525
2526         /*
2527          * drum roll: don't forget to set
2528          * the net device is belong to
2529          */
2530         dev_net_set(dev, net);
2531
2532         ret = -EEXIST;
2533         mutex_lock(&pn->all_ppp_mutex);
2534
2535         if (unit < 0) {
2536                 unit = unit_get(&pn->units_idr, ppp);
2537                 if (unit < 0) {
2538                         *retp = unit;
2539                         goto out2;
2540                 }
2541         } else {
2542                 if (unit_find(&pn->units_idr, unit))
2543                         goto out2; /* unit already exists */
2544                 /*
2545                  * if caller need a specified unit number
2546                  * lets try to satisfy him, otherwise --
2547                  * he should better ask us for new unit number
2548                  *
2549                  * NOTE: yes I know that returning EEXIST it's not
2550                  * fair but at least pppd will ask us to allocate
2551                  * new unit in this case so user is happy :)
2552                  */
2553                 unit = unit_set(&pn->units_idr, ppp, unit);
2554                 if (unit < 0)
2555                         goto out2;
2556         }
2557
2558         /* Initialize the new ppp unit */
2559         ppp->file.index = unit;
2560         sprintf(dev->name, "ppp%d", unit);
2561
2562         ret = register_netdev(dev);
2563         if (ret != 0) {
2564                 unit_put(&pn->units_idr, unit);
2565                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2566                        dev->name, ret);
2567                 goto out2;
2568         }
2569
2570         ppp->ppp_net = net;
2571
2572         atomic_inc(&ppp_unit_count);
2573         mutex_unlock(&pn->all_ppp_mutex);
2574
2575         *retp = 0;
2576         return ppp;
2577
2578 out2:
2579         mutex_unlock(&pn->all_ppp_mutex);
2580         free_netdev(dev);
2581 out1:
2582         *retp = ret;
2583         return NULL;
2584 }
2585
2586 /*
2587  * Initialize a ppp_file structure.
2588  */
2589 static void
2590 init_ppp_file(struct ppp_file *pf, int kind)
2591 {
2592         pf->kind = kind;
2593         skb_queue_head_init(&pf->xq);
2594         skb_queue_head_init(&pf->rq);
2595         atomic_set(&pf->refcnt, 1);
2596         init_waitqueue_head(&pf->rwait);
2597 }
2598
2599 /*
2600  * Take down a ppp interface unit - called when the owning file
2601  * (the one that created the unit) is closed or detached.
2602  */
2603 static void ppp_shutdown_interface(struct ppp *ppp)
2604 {
2605         struct ppp_net *pn;
2606
2607         pn = ppp_pernet(ppp->ppp_net);
2608         mutex_lock(&pn->all_ppp_mutex);
2609
2610         /* This will call dev_close() for us. */
2611         ppp_lock(ppp);
2612         if (!ppp->closing) {
2613                 ppp->closing = 1;
2614                 ppp_unlock(ppp);
2615                 unregister_netdev(ppp->dev);
2616         } else
2617                 ppp_unlock(ppp);
2618
2619         unit_put(&pn->units_idr, ppp->file.index);
2620         ppp->file.dead = 1;
2621         ppp->owner = NULL;
2622         wake_up_interruptible(&ppp->file.rwait);
2623
2624         mutex_unlock(&pn->all_ppp_mutex);
2625 }
2626
2627 /*
2628  * Free the memory used by a ppp unit.  This is only called once
2629  * there are no channels connected to the unit and no file structs
2630  * that reference the unit.
2631  */
2632 static void ppp_destroy_interface(struct ppp *ppp)
2633 {
2634         atomic_dec(&ppp_unit_count);
2635
2636         if (!ppp->file.dead || ppp->n_channels) {
2637                 /* "can't happen" */
2638                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2639                        "n_channels=%d !\n", ppp, ppp->file.dead,
2640                        ppp->n_channels);
2641                 return;
2642         }
2643
2644         ppp_ccp_closed(ppp);
2645         if (ppp->vj) {
2646                 slhc_free(ppp->vj);
2647                 ppp->vj = NULL;
2648         }
2649         skb_queue_purge(&ppp->file.xq);
2650         skb_queue_purge(&ppp->file.rq);
2651 #ifdef CONFIG_PPP_MULTILINK
2652         skb_queue_purge(&ppp->mrq);
2653 #endif /* CONFIG_PPP_MULTILINK */
2654 #ifdef CONFIG_PPP_FILTER
2655         kfree(ppp->pass_filter);
2656         ppp->pass_filter = NULL;
2657         kfree(ppp->active_filter);
2658         ppp->active_filter = NULL;
2659 #endif /* CONFIG_PPP_FILTER */
2660
2661         if (ppp->xmit_pending)
2662                 kfree_skb(ppp->xmit_pending);
2663
2664         free_netdev(ppp->dev);
2665 }
2666
2667 /*
2668  * Locate an existing ppp unit.
2669  * The caller should have locked the all_ppp_mutex.
2670  */
2671 static struct ppp *
2672 ppp_find_unit(struct ppp_net *pn, int unit)
2673 {
2674         return unit_find(&pn->units_idr, unit);
2675 }
2676
2677 /*
2678  * Locate an existing ppp channel.
2679  * The caller should have locked the all_channels_lock.
2680  * First we look in the new_channels list, then in the
2681  * all_channels list.  If found in the new_channels list,
2682  * we move it to the all_channels list.  This is for speed
2683  * when we have a lot of channels in use.
2684  */
2685 static struct channel *
2686 ppp_find_channel(struct ppp_net *pn, int unit)
2687 {
2688         struct channel *pch;
2689
2690         list_for_each_entry(pch, &pn->new_channels, list) {
2691                 if (pch->file.index == unit) {
2692                         list_move(&pch->list, &pn->all_channels);
2693                         return pch;
2694                 }
2695         }
2696
2697         list_for_each_entry(pch, &pn->all_channels, list) {
2698                 if (pch->file.index == unit)
2699                         return pch;
2700         }
2701
2702         return NULL;
2703 }
2704
2705 /*
2706  * Connect a PPP channel to a PPP interface unit.
2707  */
2708 static int
2709 ppp_connect_channel(struct channel *pch, int unit)
2710 {
2711         struct ppp *ppp;
2712         struct ppp_net *pn;
2713         int ret = -ENXIO;
2714         int hdrlen;
2715
2716         pn = ppp_pernet(pch->chan_net);
2717
2718         mutex_lock(&pn->all_ppp_mutex);
2719         ppp = ppp_find_unit(pn, unit);
2720         if (!ppp)
2721                 goto out;
2722         write_lock_bh(&pch->upl);
2723         ret = -EINVAL;
2724         if (pch->ppp)
2725                 goto outl;
2726
2727         ppp_lock(ppp);
2728         if (pch->file.hdrlen > ppp->file.hdrlen)
2729                 ppp->file.hdrlen = pch->file.hdrlen;
2730         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2731         if (hdrlen > ppp->dev->hard_header_len)
2732                 ppp->dev->hard_header_len = hdrlen;
2733         list_add_tail(&pch->clist, &ppp->channels);
2734         ++ppp->n_channels;
2735         pch->ppp = ppp;
2736         atomic_inc(&ppp->file.refcnt);
2737         ppp_unlock(ppp);
2738         ret = 0;
2739
2740  outl:
2741         write_unlock_bh(&pch->upl);
2742  out:
2743         mutex_unlock(&pn->all_ppp_mutex);
2744         return ret;
2745 }
2746
2747 /*
2748  * Disconnect a channel from its ppp unit.
2749  */
2750 static int
2751 ppp_disconnect_channel(struct channel *pch)
2752 {
2753         struct ppp *ppp;
2754         int err = -EINVAL;
2755
2756         write_lock_bh(&pch->upl);
2757         ppp = pch->ppp;
2758         pch->ppp = NULL;
2759         write_unlock_bh(&pch->upl);
2760         if (ppp) {
2761                 /* remove it from the ppp unit's list */
2762                 ppp_lock(ppp);
2763                 list_del(&pch->clist);
2764                 if (--ppp->n_channels == 0)
2765                         wake_up_interruptible(&ppp->file.rwait);
2766                 ppp_unlock(ppp);
2767                 if (atomic_dec_and_test(&ppp->file.refcnt))
2768                         ppp_destroy_interface(ppp);
2769                 err = 0;
2770         }
2771         return err;
2772 }
2773
2774 /*
2775  * Free up the resources used by a ppp channel.
2776  */
2777 static void ppp_destroy_channel(struct channel *pch)
2778 {
2779         atomic_dec(&channel_count);
2780
2781         if (!pch->file.dead) {
2782                 /* "can't happen" */
2783                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2784                        pch);
2785                 return;
2786         }
2787         skb_queue_purge(&pch->file.xq);
2788         skb_queue_purge(&pch->file.rq);
2789         kfree(pch);
2790 }
2791
2792 static void __exit ppp_cleanup(void)
2793 {
2794         /* should never happen */
2795         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2796                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2797         unregister_chrdev(PPP_MAJOR, "ppp");
2798         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2799         class_destroy(ppp_class);
2800         unregister_pernet_gen_device(ppp_net_id, &ppp_net_ops);
2801 }
2802
2803 /*
2804  * Units handling. Caller must protect concurrent access
2805  * by holding all_ppp_mutex
2806  */
2807
2808 /* associate pointer with specified number */
2809 static int unit_set(struct idr *p, void *ptr, int n)
2810 {
2811         int unit, err;
2812
2813 again:
2814         if (!idr_pre_get(p, GFP_KERNEL)) {
2815                 printk(KERN_ERR "PPP: No free memory for idr\n");
2816                 return -ENOMEM;
2817         }
2818
2819         err = idr_get_new_above(p, ptr, n, &unit);
2820         if (err == -EAGAIN)
2821                 goto again;
2822
2823         if (unit != n) {
2824                 idr_remove(p, unit);
2825                 return -EINVAL;
2826         }
2827
2828         return unit;
2829 }
2830
2831 /* get new free unit number and associate pointer with it */
2832 static int unit_get(struct idr *p, void *ptr)
2833 {
2834         int unit, err;
2835
2836 again:
2837         if (!idr_pre_get(p, GFP_KERNEL)) {
2838                 printk(KERN_ERR "PPP: No free memory for idr\n");
2839                 return -ENOMEM;
2840         }
2841
2842         err = idr_get_new_above(p, ptr, 0, &unit);
2843         if (err == -EAGAIN)
2844                 goto again;
2845
2846         return unit;
2847 }
2848
2849 /* put unit number back to a pool */
2850 static void unit_put(struct idr *p, int n)
2851 {
2852         idr_remove(p, n);
2853 }
2854
2855 /* get pointer associated with the number */
2856 static void *unit_find(struct idr *p, int n)
2857 {
2858         return idr_find(p, n);
2859 }
2860
2861 /* Module/initialization stuff */
2862
2863 module_init(ppp_init);
2864 module_exit(ppp_cleanup);
2865
2866 EXPORT_SYMBOL(ppp_register_net_channel);
2867 EXPORT_SYMBOL(ppp_register_channel);
2868 EXPORT_SYMBOL(ppp_unregister_channel);
2869 EXPORT_SYMBOL(ppp_channel_index);
2870 EXPORT_SYMBOL(ppp_unit_number);
2871 EXPORT_SYMBOL(ppp_input);
2872 EXPORT_SYMBOL(ppp_input_error);
2873 EXPORT_SYMBOL(ppp_output_wakeup);
2874 EXPORT_SYMBOL(ppp_register_compressor);
2875 EXPORT_SYMBOL(ppp_unregister_compressor);
2876 MODULE_LICENSE("GPL");
2877 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2878 MODULE_ALIAS("/dev/ppp");