Version:  2.0.40 2.2.26 2.4.37 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15

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

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