Version:  2.0.40 2.2.26 2.4.37 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 3.16

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;
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         *p = code;
558         return uprog.len;
559 }
560 #endif /* CONFIG_PPP_FILTER */
561 
562 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
563 {
564         struct ppp_file *pf = file->private_data;
565         struct ppp *ppp;
566         int err = -EFAULT, val, val2, i;
567         struct ppp_idle idle;
568         struct npioctl npi;
569         int unit, cflags;
570         struct slcompress *vj;
571         void __user *argp = (void __user *)arg;
572         int __user *p = argp;
573 
574         if (!pf)
575                 return ppp_unattached_ioctl(current->nsproxy->net_ns,
576                                         pf, file, cmd, arg);
577 
578         if (cmd == PPPIOCDETACH) {
579                 /*
580                  * We have to be careful here... if the file descriptor
581                  * has been dup'd, we could have another process in the
582                  * middle of a poll using the same file *, so we had
583                  * better not free the interface data structures -
584                  * instead we fail the ioctl.  Even in this case, we
585                  * shut down the interface if we are the owner of it.
586                  * Actually, we should get rid of PPPIOCDETACH, userland
587                  * (i.e. pppd) could achieve the same effect by closing
588                  * this fd and reopening /dev/ppp.
589                  */
590                 err = -EINVAL;
591                 mutex_lock(&ppp_mutex);
592                 if (pf->kind == INTERFACE) {
593                         ppp = PF_TO_PPP(pf);
594                         if (file == ppp->owner)
595                                 ppp_shutdown_interface(ppp);
596                 }
597                 if (atomic_long_read(&file->f_count) <= 2) {
598                         ppp_release(NULL, file);
599                         err = 0;
600                 } else
601                         pr_warn("PPPIOCDETACH file->f_count=%ld\n",
602                                 atomic_long_read(&file->f_count));
603                 mutex_unlock(&ppp_mutex);
604                 return err;
605         }
606 
607         if (pf->kind == CHANNEL) {
608                 struct channel *pch;
609                 struct ppp_channel *chan;
610 
611                 mutex_lock(&ppp_mutex);
612                 pch = PF_TO_CHANNEL(pf);
613 
614                 switch (cmd) {
615                 case PPPIOCCONNECT:
616                         if (get_user(unit, p))
617                                 break;
618                         err = ppp_connect_channel(pch, unit);
619                         break;
620 
621                 case PPPIOCDISCONN:
622                         err = ppp_disconnect_channel(pch);
623                         break;
624 
625                 default:
626                         down_read(&pch->chan_sem);
627                         chan = pch->chan;
628                         err = -ENOTTY;
629                         if (chan && chan->ops->ioctl)
630                                 err = chan->ops->ioctl(chan, cmd, arg);
631                         up_read(&pch->chan_sem);
632                 }
633                 mutex_unlock(&ppp_mutex);
634                 return err;
635         }
636 
637         if (pf->kind != INTERFACE) {
638                 /* can't happen */
639                 pr_err("PPP: not interface or channel??\n");
640                 return -EINVAL;
641         }
642 
643         mutex_lock(&ppp_mutex);
644         ppp = PF_TO_PPP(pf);
645         switch (cmd) {
646         case PPPIOCSMRU:
647                 if (get_user(val, p))
648                         break;
649                 ppp->mru = val;
650                 err = 0;
651                 break;
652 
653         case PPPIOCSFLAGS:
654                 if (get_user(val, p))
655                         break;
656                 ppp_lock(ppp);
657                 cflags = ppp->flags & ~val;
658                 ppp->flags = val & SC_FLAG_BITS;
659                 ppp_unlock(ppp);
660                 if (cflags & SC_CCP_OPEN)
661                         ppp_ccp_closed(ppp);
662                 err = 0;
663                 break;
664 
665         case PPPIOCGFLAGS:
666                 val = ppp->flags | ppp->xstate | ppp->rstate;
667                 if (put_user(val, p))
668                         break;
669                 err = 0;
670                 break;
671 
672         case PPPIOCSCOMPRESS:
673                 err = ppp_set_compress(ppp, arg);
674                 break;
675 
676         case PPPIOCGUNIT:
677                 if (put_user(ppp->file.index, p))
678                         break;
679                 err = 0;
680                 break;
681 
682         case PPPIOCSDEBUG:
683                 if (get_user(val, p))
684                         break;
685                 ppp->debug = val;
686                 err = 0;
687                 break;
688 
689         case PPPIOCGDEBUG:
690                 if (put_user(ppp->debug, p))
691                         break;
692                 err = 0;
693                 break;
694 
695         case PPPIOCGIDLE:
696                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
697                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
698                 if (copy_to_user(argp, &idle, sizeof(idle)))
699                         break;
700                 err = 0;
701                 break;
702 
703         case PPPIOCSMAXCID:
704                 if (get_user(val, p))
705                         break;
706                 val2 = 15;
707                 if ((val >> 16) != 0) {
708                         val2 = val >> 16;
709                         val &= 0xffff;
710                 }
711                 vj = slhc_init(val2+1, val+1);
712                 if (!vj) {
713                         netdev_err(ppp->dev,
714                                    "PPP: no memory (VJ compressor)\n");
715                         err = -ENOMEM;
716                         break;
717                 }
718                 ppp_lock(ppp);
719                 if (ppp->vj)
720                         slhc_free(ppp->vj);
721                 ppp->vj = vj;
722                 ppp_unlock(ppp);
723                 err = 0;
724                 break;
725 
726         case PPPIOCGNPMODE:
727         case PPPIOCSNPMODE:
728                 if (copy_from_user(&npi, argp, sizeof(npi)))
729                         break;
730                 err = proto_to_npindex(npi.protocol);
731                 if (err < 0)
732                         break;
733                 i = err;
734                 if (cmd == PPPIOCGNPMODE) {
735                         err = -EFAULT;
736                         npi.mode = ppp->npmode[i];
737                         if (copy_to_user(argp, &npi, sizeof(npi)))
738                                 break;
739                 } else {
740                         ppp->npmode[i] = npi.mode;
741                         /* we may be able to transmit more packets now (??) */
742                         netif_wake_queue(ppp->dev);
743                 }
744                 err = 0;
745                 break;
746 
747 #ifdef CONFIG_PPP_FILTER
748         case PPPIOCSPASS:
749         {
750                 struct sock_filter *code;
751 
752                 err = get_filter(argp, &code);
753                 if (err >= 0) {
754                         struct sock_fprog_kern fprog = {
755                                 .len = err,
756                                 .filter = code,
757                         };
758 
759                         ppp_lock(ppp);
760                         if (ppp->pass_filter) {
761                                 sk_unattached_filter_destroy(ppp->pass_filter);
762                                 ppp->pass_filter = NULL;
763                         }
764                         if (fprog.filter != NULL)
765                                 err = sk_unattached_filter_create(&ppp->pass_filter,
766                                                                   &fprog);
767                         else
768                                 err = 0;
769                         kfree(code);
770                         ppp_unlock(ppp);
771                 }
772                 break;
773         }
774         case PPPIOCSACTIVE:
775         {
776                 struct sock_filter *code;
777 
778                 err = get_filter(argp, &code);
779                 if (err >= 0) {
780                         struct sock_fprog_kern fprog = {
781                                 .len = err,
782                                 .filter = code,
783                         };
784 
785                         ppp_lock(ppp);
786                         if (ppp->active_filter) {
787                                 sk_unattached_filter_destroy(ppp->active_filter);
788                                 ppp->active_filter = NULL;
789                         }
790                         if (fprog.filter != NULL)
791                                 err = sk_unattached_filter_create(&ppp->active_filter,
792                                                                   &fprog);
793                         else
794                                 err = 0;
795                         kfree(code);
796                         ppp_unlock(ppp);
797                 }
798                 break;
799         }
800 #endif /* CONFIG_PPP_FILTER */
801 
802 #ifdef CONFIG_PPP_MULTILINK
803         case PPPIOCSMRRU:
804                 if (get_user(val, p))
805                         break;
806                 ppp_recv_lock(ppp);
807                 ppp->mrru = val;
808                 ppp_recv_unlock(ppp);
809                 err = 0;
810                 break;
811 #endif /* CONFIG_PPP_MULTILINK */
812 
813         default:
814                 err = -ENOTTY;
815         }
816         mutex_unlock(&ppp_mutex);
817         return err;
818 }
819 
820 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
821                         struct file *file, unsigned int cmd, unsigned long arg)
822 {
823         int unit, err = -EFAULT;
824         struct ppp *ppp;
825         struct channel *chan;
826         struct ppp_net *pn;
827         int __user *p = (int __user *)arg;
828 
829         mutex_lock(&ppp_mutex);
830         switch (cmd) {
831         case PPPIOCNEWUNIT:
832                 /* Create a new ppp unit */
833                 if (get_user(unit, p))
834                         break;
835                 ppp = ppp_create_interface(net, unit, &err);
836                 if (!ppp)
837                         break;
838                 file->private_data = &ppp->file;
839                 ppp->owner = file;
840                 err = -EFAULT;
841                 if (put_user(ppp->file.index, p))
842                         break;
843                 err = 0;
844                 break;
845 
846         case PPPIOCATTACH:
847                 /* Attach to an existing ppp unit */
848                 if (get_user(unit, p))
849                         break;
850                 err = -ENXIO;
851                 pn = ppp_pernet(net);
852                 mutex_lock(&pn->all_ppp_mutex);
853                 ppp = ppp_find_unit(pn, unit);
854                 if (ppp) {
855                         atomic_inc(&ppp->file.refcnt);
856                         file->private_data = &ppp->file;
857                         err = 0;
858                 }
859                 mutex_unlock(&pn->all_ppp_mutex);
860                 break;
861 
862         case PPPIOCATTCHAN:
863                 if (get_user(unit, p))
864                         break;
865                 err = -ENXIO;
866                 pn = ppp_pernet(net);
867                 spin_lock_bh(&pn->all_channels_lock);
868                 chan = ppp_find_channel(pn, unit);
869                 if (chan) {
870                         atomic_inc(&chan->file.refcnt);
871                         file->private_data = &chan->file;
872                         err = 0;
873                 }
874                 spin_unlock_bh(&pn->all_channels_lock);
875                 break;
876 
877         default:
878                 err = -ENOTTY;
879         }
880         mutex_unlock(&ppp_mutex);
881         return err;
882 }
883 
884 static const struct file_operations ppp_device_fops = {
885         .owner          = THIS_MODULE,
886         .read           = ppp_read,
887         .write          = ppp_write,
888         .poll           = ppp_poll,
889         .unlocked_ioctl = ppp_ioctl,
890         .open           = ppp_open,
891         .release        = ppp_release,
892         .llseek         = noop_llseek,
893 };
894 
895 static __net_init int ppp_init_net(struct net *net)
896 {
897         struct ppp_net *pn = net_generic(net, ppp_net_id);
898 
899         idr_init(&pn->units_idr);
900         mutex_init(&pn->all_ppp_mutex);
901 
902         INIT_LIST_HEAD(&pn->all_channels);
903         INIT_LIST_HEAD(&pn->new_channels);
904 
905         spin_lock_init(&pn->all_channels_lock);
906 
907         return 0;
908 }
909 
910 static __net_exit void ppp_exit_net(struct net *net)
911 {
912         struct ppp_net *pn = net_generic(net, ppp_net_id);
913 
914         idr_destroy(&pn->units_idr);
915 }
916 
917 static struct pernet_operations ppp_net_ops = {
918         .init = ppp_init_net,
919         .exit = ppp_exit_net,
920         .id   = &ppp_net_id,
921         .size = sizeof(struct ppp_net),
922 };
923 
924 #define PPP_MAJOR       108
925 
926 /* Called at boot time if ppp is compiled into the kernel,
927    or at module load time (from init_module) if compiled as a module. */
928 static int __init ppp_init(void)
929 {
930         int err;
931 
932         pr_info("PPP generic driver version " PPP_VERSION "\n");
933 
934         err = register_pernet_device(&ppp_net_ops);
935         if (err) {
936                 pr_err("failed to register PPP pernet device (%d)\n", err);
937                 goto out;
938         }
939 
940         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
941         if (err) {
942                 pr_err("failed to register PPP device (%d)\n", err);
943                 goto out_net;
944         }
945 
946         ppp_class = class_create(THIS_MODULE, "ppp");
947         if (IS_ERR(ppp_class)) {
948                 err = PTR_ERR(ppp_class);
949                 goto out_chrdev;
950         }
951 
952         /* not a big deal if we fail here :-) */
953         device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
954 
955         return 0;
956 
957 out_chrdev:
958         unregister_chrdev(PPP_MAJOR, "ppp");
959 out_net:
960         unregister_pernet_device(&ppp_net_ops);
961 out:
962         return err;
963 }
964 
965 /*
966  * Network interface unit routines.
967  */
968 static netdev_tx_t
969 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
970 {
971         struct ppp *ppp = netdev_priv(dev);
972         int npi, proto;
973         unsigned char *pp;
974 
975         npi = ethertype_to_npindex(ntohs(skb->protocol));
976         if (npi < 0)
977                 goto outf;
978 
979         /* Drop, accept or reject the packet */
980         switch (ppp->npmode[npi]) {
981         case NPMODE_PASS:
982                 break;
983         case NPMODE_QUEUE:
984                 /* it would be nice to have a way to tell the network
985                    system to queue this one up for later. */
986                 goto outf;
987         case NPMODE_DROP:
988         case NPMODE_ERROR:
989                 goto outf;
990         }
991 
992         /* Put the 2-byte PPP protocol number on the front,
993            making sure there is room for the address and control fields. */
994         if (skb_cow_head(skb, PPP_HDRLEN))
995                 goto outf;
996 
997         pp = skb_push(skb, 2);
998         proto = npindex_to_proto[npi];
999         put_unaligned_be16(proto, pp);
1000 
1001         skb_queue_tail(&ppp->file.xq, skb);
1002         ppp_xmit_process(ppp);
1003         return NETDEV_TX_OK;
1004 
1005  outf:
1006         kfree_skb(skb);
1007         ++dev->stats.tx_dropped;
1008         return NETDEV_TX_OK;
1009 }
1010 
1011 static int
1012 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
1013 {
1014         struct ppp *ppp = netdev_priv(dev);
1015         int err = -EFAULT;
1016         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
1017         struct ppp_stats stats;
1018         struct ppp_comp_stats cstats;
1019         char *vers;
1020 
1021         switch (cmd) {
1022         case SIOCGPPPSTATS:
1023                 ppp_get_stats(ppp, &stats);
1024                 if (copy_to_user(addr, &stats, sizeof(stats)))
1025                         break;
1026                 err = 0;
1027                 break;
1028 
1029         case SIOCGPPPCSTATS:
1030                 memset(&cstats, 0, sizeof(cstats));
1031                 if (ppp->xc_state)
1032                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
1033                 if (ppp->rc_state)
1034                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
1035                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
1036                         break;
1037                 err = 0;
1038                 break;
1039 
1040         case SIOCGPPPVER:
1041                 vers = PPP_VERSION;
1042                 if (copy_to_user(addr, vers, strlen(vers) + 1))
1043                         break;
1044                 err = 0;
1045                 break;
1046 
1047         default:
1048                 err = -EINVAL;
1049         }
1050 
1051         return err;
1052 }
1053 
1054 static struct rtnl_link_stats64*
1055 ppp_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats64)
1056 {
1057         struct ppp *ppp = netdev_priv(dev);
1058 
1059         ppp_recv_lock(ppp);
1060         stats64->rx_packets = ppp->stats64.rx_packets;
1061         stats64->rx_bytes   = ppp->stats64.rx_bytes;
1062         ppp_recv_unlock(ppp);
1063 
1064         ppp_xmit_lock(ppp);
1065         stats64->tx_packets = ppp->stats64.tx_packets;
1066         stats64->tx_bytes   = ppp->stats64.tx_bytes;
1067         ppp_xmit_unlock(ppp);
1068 
1069         stats64->rx_errors        = dev->stats.rx_errors;
1070         stats64->tx_errors        = dev->stats.tx_errors;
1071         stats64->rx_dropped       = dev->stats.rx_dropped;
1072         stats64->tx_dropped       = dev->stats.tx_dropped;
1073         stats64->rx_length_errors = dev->stats.rx_length_errors;
1074 
1075         return stats64;
1076 }
1077 
1078 static struct lock_class_key ppp_tx_busylock;
1079 static int ppp_dev_init(struct net_device *dev)
1080 {
1081         dev->qdisc_tx_busylock = &ppp_tx_busylock;
1082         return 0;
1083 }
1084 
1085 static const struct net_device_ops ppp_netdev_ops = {
1086         .ndo_init        = ppp_dev_init,
1087         .ndo_start_xmit  = ppp_start_xmit,
1088         .ndo_do_ioctl    = ppp_net_ioctl,
1089         .ndo_get_stats64 = ppp_get_stats64,
1090 };
1091 
1092 static void ppp_setup(struct net_device *dev)
1093 {
1094         dev->netdev_ops = &ppp_netdev_ops;
1095         dev->hard_header_len = PPP_HDRLEN;
1096         dev->mtu = PPP_MRU;
1097         dev->addr_len = 0;
1098         dev->tx_queue_len = 3;
1099         dev->type = ARPHRD_PPP;
1100         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1101         dev->features |= NETIF_F_NETNS_LOCAL;
1102         dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
1103 }
1104 
1105 /*
1106  * Transmit-side routines.
1107  */
1108 
1109 /*
1110  * Called to do any work queued up on the transmit side
1111  * that can now be done.
1112  */
1113 static void
1114 ppp_xmit_process(struct ppp *ppp)
1115 {
1116         struct sk_buff *skb;
1117 
1118         ppp_xmit_lock(ppp);
1119         if (!ppp->closing) {
1120                 ppp_push(ppp);
1121                 while (!ppp->xmit_pending &&
1122                        (skb = skb_dequeue(&ppp->file.xq)))
1123                         ppp_send_frame(ppp, skb);
1124                 /* If there's no work left to do, tell the core net
1125                    code that we can accept some more. */
1126                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1127                         netif_wake_queue(ppp->dev);
1128                 else
1129                         netif_stop_queue(ppp->dev);
1130         }
1131         ppp_xmit_unlock(ppp);
1132 }
1133 
1134 static inline struct sk_buff *
1135 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1136 {
1137         struct sk_buff *new_skb;
1138         int len;
1139         int new_skb_size = ppp->dev->mtu +
1140                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1141         int compressor_skb_size = ppp->dev->mtu +
1142                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1143         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1144         if (!new_skb) {
1145                 if (net_ratelimit())
1146                         netdev_err(ppp->dev, "PPP: no memory (comp pkt)\n");
1147                 return NULL;
1148         }
1149         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1150                 skb_reserve(new_skb,
1151                             ppp->dev->hard_header_len - PPP_HDRLEN);
1152 
1153         /* compressor still expects A/C bytes in hdr */
1154         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1155                                    new_skb->data, skb->len + 2,
1156                                    compressor_skb_size);
1157         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1158                 consume_skb(skb);
1159                 skb = new_skb;
1160                 skb_put(skb, len);
1161                 skb_pull(skb, 2);       /* pull off A/C bytes */
1162         } else if (len == 0) {
1163                 /* didn't compress, or CCP not up yet */
1164                 consume_skb(new_skb);
1165                 new_skb = skb;
1166         } else {
1167                 /*
1168                  * (len < 0)
1169                  * MPPE requires that we do not send unencrypted
1170                  * frames.  The compressor will return -1 if we
1171                  * should drop the frame.  We cannot simply test
1172                  * the compress_proto because MPPE and MPPC share
1173                  * the same number.
1174                  */
1175                 if (net_ratelimit())
1176                         netdev_err(ppp->dev, "ppp: compressor dropped pkt\n");
1177                 kfree_skb(skb);
1178                 consume_skb(new_skb);
1179                 new_skb = NULL;
1180         }
1181         return new_skb;
1182 }
1183 
1184 /*
1185  * Compress and send a frame.
1186  * The caller should have locked the xmit path,
1187  * and xmit_pending should be 0.
1188  */
1189 static void
1190 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1191 {
1192         int proto = PPP_PROTO(skb);
1193         struct sk_buff *new_skb;
1194         int len;
1195         unsigned char *cp;
1196 
1197         if (proto < 0x8000) {
1198 #ifdef CONFIG_PPP_FILTER
1199                 /* check if we should pass this packet */
1200                 /* the filter instructions are constructed assuming
1201                    a four-byte PPP header on each packet */
1202                 *skb_push(skb, 2) = 1;
1203                 if (ppp->pass_filter &&
1204                     SK_RUN_FILTER(ppp->pass_filter, skb) == 0) {
1205                         if (ppp->debug & 1)
1206                                 netdev_printk(KERN_DEBUG, ppp->dev,
1207                                               "PPP: outbound frame "
1208                                               "not passed\n");
1209                         kfree_skb(skb);
1210                         return;
1211                 }
1212                 /* if this packet passes the active filter, record the time */
1213                 if (!(ppp->active_filter &&
1214                       SK_RUN_FILTER(ppp->active_filter, skb) == 0))
1215                         ppp->last_xmit = jiffies;
1216                 skb_pull(skb, 2);
1217 #else
1218                 /* for data packets, record the time */
1219                 ppp->last_xmit = jiffies;
1220 #endif /* CONFIG_PPP_FILTER */
1221         }
1222 
1223         ++ppp->stats64.tx_packets;
1224         ppp->stats64.tx_bytes += skb->len - 2;
1225 
1226         switch (proto) {
1227         case PPP_IP:
1228                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1229                         break;
1230                 /* try to do VJ TCP header compression */
1231                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1232                                     GFP_ATOMIC);
1233                 if (!new_skb) {
1234                         netdev_err(ppp->dev, "PPP: no memory (VJ comp pkt)\n");
1235                         goto drop;
1236                 }
1237                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1238                 cp = skb->data + 2;
1239                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1240                                     new_skb->data + 2, &cp,
1241                                     !(ppp->flags & SC_NO_TCP_CCID));
1242                 if (cp == skb->data + 2) {
1243                         /* didn't compress */
1244                         consume_skb(new_skb);
1245                 } else {
1246                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1247                                 proto = PPP_VJC_COMP;
1248                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1249                         } else {
1250                                 proto = PPP_VJC_UNCOMP;
1251                                 cp[0] = skb->data[2];
1252                         }
1253                         consume_skb(skb);
1254                         skb = new_skb;
1255                         cp = skb_put(skb, len + 2);
1256                         cp[0] = 0;
1257                         cp[1] = proto;
1258                 }
1259                 break;
1260 
1261         case PPP_CCP:
1262                 /* peek at outbound CCP frames */
1263                 ppp_ccp_peek(ppp, skb, 0);
1264                 break;
1265         }
1266 
1267         /* try to do packet compression */
1268         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state &&
1269             proto != PPP_LCP && proto != PPP_CCP) {
1270                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1271                         if (net_ratelimit())
1272                                 netdev_err(ppp->dev,
1273                                            "ppp: compression required but "
1274                                            "down - pkt dropped.\n");
1275                         goto drop;
1276                 }
1277                 skb = pad_compress_skb(ppp, skb);
1278                 if (!skb)
1279                         goto drop;
1280         }
1281 
1282         /*
1283          * If we are waiting for traffic (demand dialling),
1284          * queue it up for pppd to receive.
1285          */
1286         if (ppp->flags & SC_LOOP_TRAFFIC) {
1287                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1288                         goto drop;
1289                 skb_queue_tail(&ppp->file.rq, skb);
1290                 wake_up_interruptible(&ppp->file.rwait);
1291                 return;
1292         }
1293 
1294         ppp->xmit_pending = skb;
1295         ppp_push(ppp);
1296         return;
1297 
1298  drop:
1299         kfree_skb(skb);
1300         ++ppp->dev->stats.tx_errors;
1301 }
1302 
1303 /*
1304  * Try to send the frame in xmit_pending.
1305  * The caller should have the xmit path locked.
1306  */
1307 static void
1308 ppp_push(struct ppp *ppp)
1309 {
1310         struct list_head *list;
1311         struct channel *pch;
1312         struct sk_buff *skb = ppp->xmit_pending;
1313 
1314         if (!skb)
1315                 return;
1316 
1317         list = &ppp->channels;
1318         if (list_empty(list)) {
1319                 /* nowhere to send the packet, just drop it */
1320                 ppp->xmit_pending = NULL;
1321                 kfree_skb(skb);
1322                 return;
1323         }
1324 
1325         if ((ppp->flags & SC_MULTILINK) == 0) {
1326                 /* not doing multilink: send it down the first channel */
1327                 list = list->next;
1328                 pch = list_entry(list, struct channel, clist);
1329 
1330                 spin_lock_bh(&pch->downl);
1331                 if (pch->chan) {
1332                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1333                                 ppp->xmit_pending = NULL;
1334                 } else {
1335                         /* channel got unregistered */
1336                         kfree_skb(skb);
1337                         ppp->xmit_pending = NULL;
1338                 }
1339                 spin_unlock_bh(&pch->downl);
1340                 return;
1341         }
1342 
1343 #ifdef CONFIG_PPP_MULTILINK
1344         /* Multilink: fragment the packet over as many links
1345            as can take the packet at the moment. */
1346         if (!ppp_mp_explode(ppp, skb))
1347                 return;
1348 #endif /* CONFIG_PPP_MULTILINK */
1349 
1350         ppp->xmit_pending = NULL;
1351         kfree_skb(skb);
1352 }
1353 
1354 #ifdef CONFIG_PPP_MULTILINK
1355 static bool mp_protocol_compress __read_mostly = true;
1356 module_param(mp_protocol_compress, bool, S_IRUGO | S_IWUSR);
1357 MODULE_PARM_DESC(mp_protocol_compress,
1358                  "compress protocol id in multilink fragments");
1359 
1360 /*
1361  * Divide a packet to be transmitted into fragments and
1362  * send them out the individual links.
1363  */
1364 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1365 {
1366         int len, totlen;
1367         int i, bits, hdrlen, mtu;
1368         int flen;
1369         int navail, nfree, nzero;
1370         int nbigger;
1371         int totspeed;
1372         int totfree;
1373         unsigned char *p, *q;
1374         struct list_head *list;
1375         struct channel *pch;
1376         struct sk_buff *frag;
1377         struct ppp_channel *chan;
1378 
1379         totspeed = 0; /*total bitrate of the bundle*/
1380         nfree = 0; /* # channels which have no packet already queued */
1381         navail = 0; /* total # of usable channels (not deregistered) */
1382         nzero = 0; /* number of channels with zero speed associated*/
1383         totfree = 0; /*total # of channels available and
1384                                   *having no queued packets before
1385                                   *starting the fragmentation*/
1386 
1387         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1388         i = 0;
1389         list_for_each_entry(pch, &ppp->channels, clist) {
1390                 if (pch->chan) {
1391                         pch->avail = 1;
1392                         navail++;
1393                         pch->speed = pch->chan->speed;
1394                 } else {
1395                         pch->avail = 0;
1396                 }
1397                 if (pch->avail) {
1398                         if (skb_queue_empty(&pch->file.xq) ||
1399                                 !pch->had_frag) {
1400                                         if (pch->speed == 0)
1401                                                 nzero++;
1402                                         else
1403                                                 totspeed += pch->speed;
1404 
1405                                         pch->avail = 2;
1406                                         ++nfree;
1407                                         ++totfree;
1408                                 }
1409                         if (!pch->had_frag && i < ppp->nxchan)
1410                                 ppp->nxchan = i;
1411                 }
1412                 ++i;
1413         }
1414         /*
1415          * Don't start sending this packet unless at least half of
1416          * the channels are free.  This gives much better TCP
1417          * performance if we have a lot of channels.
1418          */
1419         if (nfree == 0 || nfree < navail / 2)
1420                 return 0; /* can't take now, leave it in xmit_pending */
1421 
1422         /* Do protocol field compression */
1423         p = skb->data;
1424         len = skb->len;
1425         if (*p == 0 && mp_protocol_compress) {
1426                 ++p;
1427                 --len;
1428         }
1429 
1430         totlen = len;
1431         nbigger = len % nfree;
1432 
1433         /* skip to the channel after the one we last used
1434            and start at that one */
1435         list = &ppp->channels;
1436         for (i = 0; i < ppp->nxchan; ++i) {
1437                 list = list->next;
1438                 if (list == &ppp->channels) {
1439                         i = 0;
1440                         break;
1441                 }
1442         }
1443 
1444         /* create a fragment for each channel */
1445         bits = B;
1446         while (len > 0) {
1447                 list = list->next;
1448                 if (list == &ppp->channels) {
1449                         i = 0;
1450                         continue;
1451                 }
1452                 pch = list_entry(list, struct channel, clist);
1453                 ++i;
1454                 if (!pch->avail)
1455                         continue;
1456 
1457                 /*
1458                  * Skip this channel if it has a fragment pending already and
1459                  * we haven't given a fragment to all of the free channels.
1460                  */
1461                 if (pch->avail == 1) {
1462                         if (nfree > 0)
1463                                 continue;
1464                 } else {
1465                         pch->avail = 1;
1466                 }
1467 
1468                 /* check the channel's mtu and whether it is still attached. */
1469                 spin_lock_bh(&pch->downl);
1470                 if (pch->chan == NULL) {
1471                         /* can't use this channel, it's being deregistered */
1472                         if (pch->speed == 0)
1473                                 nzero--;
1474                         else
1475                                 totspeed -= pch->speed;
1476 
1477                         spin_unlock_bh(&pch->downl);
1478                         pch->avail = 0;
1479                         totlen = len;
1480                         totfree--;
1481                         nfree--;
1482                         if (--navail == 0)
1483                                 break;
1484                         continue;
1485                 }
1486 
1487                 /*
1488                 *if the channel speed is not set divide
1489                 *the packet evenly among the free channels;
1490                 *otherwise divide it according to the speed
1491                 *of the channel we are going to transmit on
1492                 */
1493                 flen = len;
1494                 if (nfree > 0) {
1495                         if (pch->speed == 0) {
1496                                 flen = len/nfree;
1497                                 if (nbigger > 0) {
1498                                         flen++;
1499                                         nbigger--;
1500                                 }
1501                         } else {
1502                                 flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
1503                                         ((totspeed*totfree)/pch->speed)) - hdrlen;
1504                                 if (nbigger > 0) {
1505                                         flen += ((totfree - nzero)*pch->speed)/totspeed;
1506                                         nbigger -= ((totfree - nzero)*pch->speed)/
1507                                                         totspeed;
1508                                 }
1509                         }
1510                         nfree--;
1511                 }
1512 
1513                 /*
1514                  *check if we are on the last channel or
1515                  *we exceded the length of the data to
1516                  *fragment
1517                  */
1518                 if ((nfree <= 0) || (flen > len))
1519                         flen = len;
1520                 /*
1521                  *it is not worth to tx on slow channels:
1522                  *in that case from the resulting flen according to the
1523                  *above formula will be equal or less than zero.
1524                  *Skip the channel in this case
1525                  */
1526                 if (flen <= 0) {
1527                         pch->avail = 2;
1528                         spin_unlock_bh(&pch->downl);
1529                         continue;
1530                 }
1531 
1532                 /*
1533                  * hdrlen includes the 2-byte PPP protocol field, but the
1534                  * MTU counts only the payload excluding the protocol field.
1535                  * (RFC1661 Section 2)
1536                  */
1537                 mtu = pch->chan->mtu - (hdrlen - 2);
1538                 if (mtu < 4)
1539                         mtu = 4;
1540                 if (flen > mtu)
1541                         flen = mtu;
1542                 if (flen == len)
1543                         bits |= E;
1544                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1545                 if (!frag)
1546                         goto noskb;
1547                 q = skb_put(frag, flen + hdrlen);
1548 
1549                 /* make the MP header */
1550                 put_unaligned_be16(PPP_MP, q);
1551                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1552                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1553                         q[3] = ppp->nxseq;
1554                 } else {
1555                         q[2] = bits;
1556                         q[3] = ppp->nxseq >> 16;
1557                         q[4] = ppp->nxseq >> 8;
1558                         q[5] = ppp->nxseq;
1559                 }
1560 
1561                 memcpy(q + hdrlen, p, flen);
1562 
1563                 /* try to send it down the channel */
1564                 chan = pch->chan;
1565                 if (!skb_queue_empty(&pch->file.xq) ||
1566                         !chan->ops->start_xmit(chan, frag))
1567                         skb_queue_tail(&pch->file.xq, frag);
1568                 pch->had_frag = 1;
1569                 p += flen;
1570                 len -= flen;
1571                 ++ppp->nxseq;
1572                 bits = 0;
1573                 spin_unlock_bh(&pch->downl);
1574         }
1575         ppp->nxchan = i;
1576 
1577         return 1;
1578 
1579  noskb:
1580         spin_unlock_bh(&pch->downl);
1581         if (ppp->debug & 1)
1582                 netdev_err(ppp->dev, "PPP: no memory (fragment)\n");
1583         ++ppp->dev->stats.tx_errors;
1584         ++ppp->nxseq;
1585         return 1;       /* abandon the frame */
1586 }
1587 #endif /* CONFIG_PPP_MULTILINK */
1588 
1589 /*
1590  * Try to send data out on a channel.
1591  */
1592 static void
1593 ppp_channel_push(struct channel *pch)
1594 {
1595         struct sk_buff *skb;
1596         struct ppp *ppp;
1597 
1598         spin_lock_bh(&pch->downl);
1599         if (pch->chan) {
1600                 while (!skb_queue_empty(&pch->file.xq)) {
1601                         skb = skb_dequeue(&pch->file.xq);
1602                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1603                                 /* put the packet back and try again later */
1604                                 skb_queue_head(&pch->file.xq, skb);
1605                                 break;
1606                         }
1607                 }
1608         } else {
1609                 /* channel got deregistered */
1610                 skb_queue_purge(&pch->file.xq);
1611         }
1612         spin_unlock_bh(&pch->downl);
1613         /* see if there is anything from the attached unit to be sent */
1614         if (skb_queue_empty(&pch->file.xq)) {
1615                 read_lock_bh(&pch->upl);
1616                 ppp = pch->ppp;
1617                 if (ppp)
1618                         ppp_xmit_process(ppp);
1619                 read_unlock_bh(&pch->upl);
1620         }
1621 }
1622 
1623 /*
1624  * Receive-side routines.
1625  */
1626 
1627 struct ppp_mp_skb_parm {
1628         u32             sequence;
1629         u8              BEbits;
1630 };
1631 #define PPP_MP_CB(skb)  ((struct ppp_mp_skb_parm *)((skb)->cb))
1632 
1633 static inline void
1634 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1635 {
1636         ppp_recv_lock(ppp);
1637         if (!ppp->closing)
1638                 ppp_receive_frame(ppp, skb, pch);
1639         else
1640                 kfree_skb(skb);
1641         ppp_recv_unlock(ppp);
1642 }
1643 
1644 void
1645 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1646 {
1647         struct channel *pch = chan->ppp;
1648         int proto;
1649 
1650         if (!pch) {
1651                 kfree_skb(skb);
1652                 return;
1653         }
1654 
1655         read_lock_bh(&pch->upl);
1656         if (!pskb_may_pull(skb, 2)) {
1657                 kfree_skb(skb);
1658                 if (pch->ppp) {
1659                         ++pch->ppp->dev->stats.rx_length_errors;
1660                         ppp_receive_error(pch->ppp);
1661                 }
1662                 goto done;
1663         }
1664 
1665         proto = PPP_PROTO(skb);
1666         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1667                 /* put it on the channel queue */
1668                 skb_queue_tail(&pch->file.rq, skb);
1669                 /* drop old frames if queue too long */
1670                 while (pch->file.rq.qlen > PPP_MAX_RQLEN &&
1671                        (skb = skb_dequeue(&pch->file.rq)))
1672                         kfree_skb(skb);
1673                 wake_up_interruptible(&pch->file.rwait);
1674         } else {
1675                 ppp_do_recv(pch->ppp, skb, pch);
1676         }
1677 
1678 done:
1679         read_unlock_bh(&pch->upl);
1680 }
1681 
1682 /* Put a 0-length skb in the receive queue as an error indication */
1683 void
1684 ppp_input_error(struct ppp_channel *chan, int code)
1685 {
1686         struct channel *pch = chan->ppp;
1687         struct sk_buff *skb;
1688 
1689         if (!pch)
1690                 return;
1691 
1692         read_lock_bh(&pch->upl);
1693         if (pch->ppp) {
1694                 skb = alloc_skb(0, GFP_ATOMIC);
1695                 if (skb) {
1696                         skb->len = 0;           /* probably unnecessary */
1697                         skb->cb[0] = code;
1698                         ppp_do_recv(pch->ppp, skb, pch);
1699                 }
1700         }
1701         read_unlock_bh(&pch->upl);
1702 }
1703 
1704 /*
1705  * We come in here to process a received frame.
1706  * The receive side of the ppp unit is locked.
1707  */
1708 static void
1709 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1710 {
1711         /* note: a 0-length skb is used as an error indication */
1712         if (skb->len > 0) {
1713 #ifdef CONFIG_PPP_MULTILINK
1714                 /* XXX do channel-level decompression here */
1715                 if (PPP_PROTO(skb) == PPP_MP)
1716                         ppp_receive_mp_frame(ppp, skb, pch);
1717                 else
1718 #endif /* CONFIG_PPP_MULTILINK */
1719                         ppp_receive_nonmp_frame(ppp, skb);
1720         } else {
1721                 kfree_skb(skb);
1722                 ppp_receive_error(ppp);
1723         }
1724 }
1725 
1726 static void
1727 ppp_receive_error(struct ppp *ppp)
1728 {
1729         ++ppp->dev->stats.rx_errors;
1730         if (ppp->vj)
1731                 slhc_toss(ppp->vj);
1732 }
1733 
1734 static void
1735 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1736 {
1737         struct sk_buff *ns;
1738         int proto, len, npi;
1739 
1740         /*
1741          * Decompress the frame, if compressed.
1742          * Note that some decompressors need to see uncompressed frames
1743          * that come in as well as compressed frames.
1744          */
1745         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN) &&
1746             (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1747                 skb = ppp_decompress_frame(ppp, skb);
1748 
1749         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1750                 goto err;
1751 
1752         proto = PPP_PROTO(skb);
1753         switch (proto) {
1754         case PPP_VJC_COMP:
1755                 /* decompress VJ compressed packets */
1756                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1757                         goto err;
1758 
1759                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1760                         /* copy to a new sk_buff with more tailroom */
1761                         ns = dev_alloc_skb(skb->len + 128);
1762                         if (!ns) {
1763                                 netdev_err(ppp->dev, "PPP: no memory "
1764                                            "(VJ decomp)\n");
1765                                 goto err;
1766                         }
1767                         skb_reserve(ns, 2);
1768                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1769                         consume_skb(skb);
1770                         skb = ns;
1771                 }
1772                 else
1773                         skb->ip_summed = CHECKSUM_NONE;
1774 
1775                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1776                 if (len <= 0) {
1777                         netdev_printk(KERN_DEBUG, ppp->dev,
1778                                       "PPP: VJ decompression error\n");
1779                         goto err;
1780                 }
1781                 len += 2;
1782                 if (len > skb->len)
1783                         skb_put(skb, len - skb->len);
1784                 else if (len < skb->len)
1785                         skb_trim(skb, len);
1786                 proto = PPP_IP;
1787                 break;
1788 
1789         case PPP_VJC_UNCOMP:
1790                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1791                         goto err;
1792 
1793                 /* Until we fix the decompressor need to make sure
1794                  * data portion is linear.
1795                  */
1796                 if (!pskb_may_pull(skb, skb->len))
1797                         goto err;
1798 
1799                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1800                         netdev_err(ppp->dev, "PPP: VJ uncompressed error\n");
1801                         goto err;
1802                 }
1803                 proto = PPP_IP;
1804                 break;
1805 
1806         case PPP_CCP:
1807                 ppp_ccp_peek(ppp, skb, 1);
1808                 break;
1809         }
1810 
1811         ++ppp->stats64.rx_packets;
1812         ppp->stats64.rx_bytes += skb->len - 2;
1813 
1814         npi = proto_to_npindex(proto);
1815         if (npi < 0) {
1816                 /* control or unknown frame - pass it to pppd */
1817                 skb_queue_tail(&ppp->file.rq, skb);
1818                 /* limit queue length by dropping old frames */
1819                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN &&
1820                        (skb = skb_dequeue(&ppp->file.rq)))
1821                         kfree_skb(skb);
1822                 /* wake up any process polling or blocking on read */
1823                 wake_up_interruptible(&ppp->file.rwait);
1824 
1825         } else {
1826                 /* network protocol frame - give it to the kernel */
1827 
1828 #ifdef CONFIG_PPP_FILTER
1829                 /* check if the packet passes the pass and active filters */
1830                 /* the filter instructions are constructed assuming
1831                    a four-byte PPP header on each packet */
1832                 if (ppp->pass_filter || ppp->active_filter) {
1833                         if (skb_unclone(skb, GFP_ATOMIC))
1834                                 goto err;
1835 
1836                         *skb_push(skb, 2) = 0;
1837                         if (ppp->pass_filter &&
1838                             SK_RUN_FILTER(ppp->pass_filter, skb) == 0) {
1839                                 if (ppp->debug & 1)
1840                                         netdev_printk(KERN_DEBUG, ppp->dev,
1841                                                       "PPP: inbound frame "
1842                                                       "not passed\n");
1843                                 kfree_skb(skb);
1844                                 return;
1845                         }
1846                         if (!(ppp->active_filter &&
1847                               SK_RUN_FILTER(ppp->active_filter, skb) == 0))
1848                                 ppp->last_recv = jiffies;
1849                         __skb_pull(skb, 2);
1850                 } else
1851 #endif /* CONFIG_PPP_FILTER */
1852                         ppp->last_recv = jiffies;
1853 
1854                 if ((ppp->dev->flags & IFF_UP) == 0 ||
1855                     ppp->npmode[npi] != NPMODE_PASS) {
1856                         kfree_skb(skb);
1857                 } else {
1858                         /* chop off protocol */
1859                         skb_pull_rcsum(skb, 2);
1860                         skb->dev = ppp->dev;
1861                         skb->protocol = htons(npindex_to_ethertype[npi]);
1862                         skb_reset_mac_header(skb);
1863                         netif_rx(skb);
1864                 }
1865         }
1866         return;
1867 
1868  err:
1869         kfree_skb(skb);
1870         ppp_receive_error(ppp);
1871 }
1872 
1873 static struct sk_buff *
1874 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1875 {
1876         int proto = PPP_PROTO(skb);
1877         struct sk_buff *ns;
1878         int len;
1879 
1880         /* Until we fix all the decompressor's need to make sure
1881          * data portion is linear.
1882          */
1883         if (!pskb_may_pull(skb, skb->len))
1884                 goto err;
1885 
1886         if (proto == PPP_COMP) {
1887                 int obuff_size;
1888 
1889                 switch(ppp->rcomp->compress_proto) {
1890                 case CI_MPPE:
1891                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1892                         break;
1893                 default:
1894                         obuff_size = ppp->mru + PPP_HDRLEN;
1895                         break;
1896                 }
1897 
1898                 ns = dev_alloc_skb(obuff_size);
1899                 if (!ns) {
1900                         netdev_err(ppp->dev, "ppp_decompress_frame: "
1901                                    "no memory\n");
1902                         goto err;
1903                 }
1904                 /* the decompressor still expects the A/C bytes in the hdr */
1905                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1906                                 skb->len + 2, ns->data, obuff_size);
1907                 if (len < 0) {
1908                         /* Pass the compressed frame to pppd as an
1909                            error indication. */
1910                         if (len == DECOMP_FATALERROR)
1911                                 ppp->rstate |= SC_DC_FERROR;
1912                         kfree_skb(ns);
1913                         goto err;
1914                 }
1915 
1916                 consume_skb(skb);
1917                 skb = ns;
1918                 skb_put(skb, len);
1919                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1920 
1921         } else {
1922                 /* Uncompressed frame - pass to decompressor so it
1923                    can update its dictionary if necessary. */
1924                 if (ppp->rcomp->incomp)
1925                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1926                                            skb->len + 2);
1927         }
1928 
1929         return skb;
1930 
1931  err:
1932         ppp->rstate |= SC_DC_ERROR;
1933         ppp_receive_error(ppp);
1934         return skb;
1935 }
1936 
1937 #ifdef CONFIG_PPP_MULTILINK
1938 /*
1939  * Receive a multilink frame.
1940  * We put it on the reconstruction queue and then pull off
1941  * as many completed frames as we can.
1942  */
1943 static void
1944 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1945 {
1946         u32 mask, seq;
1947         struct channel *ch;
1948         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1949 
1950         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1951                 goto err;               /* no good, throw it away */
1952 
1953         /* Decode sequence number and begin/end bits */
1954         if (ppp->flags & SC_MP_SHORTSEQ) {
1955                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1956                 mask = 0xfff;
1957         } else {
1958                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1959                 mask = 0xffffff;
1960         }
1961         PPP_MP_CB(skb)->BEbits = skb->data[2];
1962         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1963 
1964         /*
1965          * Do protocol ID decompression on the first fragment of each packet.
1966          */
1967         if ((PPP_MP_CB(skb)->BEbits & B) && (skb->data[0] & 1))
1968                 *skb_push(skb, 1) = 0;
1969 
1970         /*
1971          * Expand sequence number to 32 bits, making it as close
1972          * as possible to ppp->minseq.
1973          */
1974         seq |= ppp->minseq & ~mask;
1975         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1976                 seq += mask + 1;
1977         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1978                 seq -= mask + 1;        /* should never happen */
1979         PPP_MP_CB(skb)->sequence = seq;
1980         pch->lastseq = seq;
1981 
1982         /*
1983          * If this packet comes before the next one we were expecting,
1984          * drop it.
1985          */
1986         if (seq_before(seq, ppp->nextseq)) {
1987                 kfree_skb(skb);
1988                 ++ppp->dev->stats.rx_dropped;
1989                 ppp_receive_error(ppp);
1990                 return;
1991         }
1992 
1993         /*
1994          * Reevaluate minseq, the minimum over all channels of the
1995          * last sequence number received on each channel.  Because of
1996          * the increasing sequence number rule, we know that any fragment
1997          * before `minseq' which hasn't arrived is never going to arrive.
1998          * The list of channels can't change because we have the receive
1999          * side of the ppp unit locked.
2000          */
2001         list_for_each_entry(ch, &ppp->channels, clist) {
2002                 if (seq_before(ch->lastseq, seq))
2003                         seq = ch->lastseq;
2004         }
2005         if (seq_before(ppp->minseq, seq))
2006                 ppp->minseq = seq;
2007 
2008         /* Put the fragment on the reconstruction queue */
2009         ppp_mp_insert(ppp, skb);
2010 
2011         /* If the queue is getting long, don't wait any longer for packets
2012            before the start of the queue. */
2013         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
2014                 struct sk_buff *mskb = skb_peek(&ppp->mrq);
2015                 if (seq_before(ppp->minseq, PPP_MP_CB(mskb)->sequence))
2016                         ppp->minseq = PPP_MP_CB(mskb)->sequence;
2017         }
2018 
2019         /* Pull completed packets off the queue and receive them. */
2020         while ((skb = ppp_mp_reconstruct(ppp))) {
2021                 if (pskb_may_pull(skb, 2))
2022                         ppp_receive_nonmp_frame(ppp, skb);
2023                 else {
2024                         ++ppp->dev->stats.rx_length_errors;
2025                         kfree_skb(skb);
2026                         ppp_receive_error(ppp);
2027                 }
2028         }
2029 
2030         return;
2031 
2032  err:
2033         kfree_skb(skb);
2034         ppp_receive_error(ppp);
2035 }
2036 
2037 /*
2038  * Insert a fragment on the MP reconstruction queue.
2039  * The queue is ordered by increasing sequence number.
2040  */
2041 static void
2042 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
2043 {
2044         struct sk_buff *p;
2045         struct sk_buff_head *list = &ppp->mrq;
2046         u32 seq = PPP_MP_CB(skb)->sequence;
2047 
2048         /* N.B. we don't need to lock the list lock because we have the
2049            ppp unit receive-side lock. */
2050         skb_queue_walk(list, p) {
2051                 if (seq_before(seq, PPP_MP_CB(p)->sequence))
2052                         break;
2053         }
2054         __skb_queue_before(list, p, skb);
2055 }
2056 
2057 /*
2058  * Reconstruct a packet from the MP fragment queue.
2059  * We go through increasing sequence numbers until we find a
2060  * complete packet, or we get to the sequence number for a fragment
2061  * which hasn't arrived but might still do so.
2062  */
2063 static struct sk_buff *
2064 ppp_mp_reconstruct(struct ppp *ppp)
2065 {
2066         u32 seq = ppp->nextseq;
2067         u32 minseq = ppp->minseq;
2068         struct sk_buff_head *list = &ppp->mrq;
2069         struct sk_buff *p, *tmp;
2070         struct sk_buff *head, *tail;
2071         struct sk_buff *skb = NULL;
2072         int lost = 0, len = 0;
2073 
2074         if (ppp->mrru == 0)     /* do nothing until mrru is set */
2075                 return NULL;
2076         head = list->next;
2077         tail = NULL;
2078         skb_queue_walk_safe(list, p, tmp) {
2079         again:
2080                 if (seq_before(PPP_MP_CB(p)->sequence, seq)) {
2081                         /* this can't happen, anyway ignore the skb */
2082                         netdev_err(ppp->dev, "ppp_mp_reconstruct bad "
2083                                    "seq %u < %u\n",
2084                                    PPP_MP_CB(p)->sequence, seq);
2085                         __skb_unlink(p, list);
2086                         kfree_skb(p);
2087                         continue;
2088                 }
2089                 if (PPP_MP_CB(p)->sequence != seq) {
2090                         u32 oldseq;
2091                         /* Fragment `seq' is missing.  If it is after
2092                            minseq, it might arrive later, so stop here. */
2093                         if (seq_after(seq, minseq))
2094                                 break;
2095                         /* Fragment `seq' is lost, keep going. */
2096                         lost = 1;
2097                         oldseq = seq;
2098                         seq = seq_before(minseq, PPP_MP_CB(p)->sequence)?
2099                                 minseq + 1: PPP_MP_CB(p)->sequence;
2100 
2101                         if (ppp->debug & 1)
2102                                 netdev_printk(KERN_DEBUG, ppp->dev,
2103                                               "lost frag %u..%u\n",
2104                                               oldseq, seq-1);
2105 
2106                         goto again;
2107                 }
2108 
2109                 /*
2110                  * At this point we know that all the fragments from
2111                  * ppp->nextseq to seq are either present or lost.
2112                  * Also, there are no complete packets in the queue
2113                  * that have no missing fragments and end before this
2114                  * fragment.
2115                  */
2116 
2117                 /* B bit set indicates this fragment starts a packet */
2118                 if (PPP_MP_CB(p)->BEbits & B) {
2119                         head = p;
2120                         lost = 0;
2121                         len = 0;
2122                 }
2123 
2124                 len += p->len;
2125 
2126                 /* Got a complete packet yet? */
2127                 if (lost == 0 && (PPP_MP_CB(p)->BEbits & E) &&
2128                     (PPP_MP_CB(head)->BEbits & B)) {
2129                         if (len > ppp->mrru + 2) {
2130                                 ++ppp->dev->stats.rx_length_errors;
2131                                 netdev_printk(KERN_DEBUG, ppp->dev,
2132                                               "PPP: reconstructed packet"
2133                                               " is too long (%d)\n", len);
2134                         } else {
2135                                 tail = p;
2136                                 break;
2137                         }
2138                         ppp->nextseq = seq + 1;
2139                 }
2140 
2141                 /*
2142                  * If this is the ending fragment of a packet,
2143                  * and we haven't found a complete valid packet yet,
2144                  * we can discard up to and including this fragment.
2145                  */
2146                 if (PPP_MP_CB(p)->BEbits & E) {
2147                         struct sk_buff *tmp2;
2148 
2149                         skb_queue_reverse_walk_from_safe(list, p, tmp2) {
2150                                 if (ppp->debug & 1)
2151                                         netdev_printk(KERN_DEBUG, ppp->dev,
2152                                                       "discarding frag %u\n",
2153                                                       PPP_MP_CB(p)->sequence);
2154                                 __skb_unlink(p, list);
2155                                 kfree_skb(p);
2156                         }
2157                         head = skb_peek(list);
2158                         if (!head)
2159                                 break;
2160                 }
2161                 ++seq;
2162         }
2163 
2164         /* If we have a complete packet, copy it all into one skb. */
2165         if (tail != NULL) {
2166                 /* If we have discarded any fragments,
2167                    signal a receive error. */
2168                 if (PPP_MP_CB(head)->sequence != ppp->nextseq) {
2169                         skb_queue_walk_safe(list, p, tmp) {
2170                                 if (p == head)
2171                                         break;
2172                                 if (ppp->debug & 1)
2173                                         netdev_printk(KERN_DEBUG, ppp->dev,
2174                                                       "discarding frag %u\n",
2175                                                       PPP_MP_CB(p)->sequence);
2176                                 __skb_unlink(p, list);
2177                                 kfree_skb(p);
2178                         }
2179 
2180                         if (ppp->debug & 1)
2181                                 netdev_printk(KERN_DEBUG, ppp->dev,
2182                                               "  missed pkts %u..%u\n",
2183                                               ppp->nextseq,
2184                                               PPP_MP_CB(head)->sequence-1);
2185                         ++ppp->dev->stats.rx_dropped;
2186                         ppp_receive_error(ppp);
2187                 }
2188 
2189                 skb = head;
2190                 if (head != tail) {
2191                         struct sk_buff **fragpp = &skb_shinfo(skb)->frag_list;
2192                         p = skb_queue_next(list, head);
2193                         __skb_unlink(skb, list);
2194                         skb_queue_walk_from_safe(list, p, tmp) {
2195                                 __skb_unlink(p, list);
2196                                 *fragpp = p;
2197                                 p->next = NULL;
2198                                 fragpp = &p->next;
2199 
2200                                 skb->len += p->len;
2201                                 skb->data_len += p->len;
2202                                 skb->truesize += p->truesize;
2203 
2204                                 if (p == tail)
2205                                         break;
2206                         }
2207                 } else {
2208                         __skb_unlink(skb, list);
2209                 }
2210 
2211                 ppp->nextseq = PPP_MP_CB(tail)->sequence + 1;
2212         }
2213 
2214         return skb;
2215 }
2216 #endif /* CONFIG_PPP_MULTILINK */
2217 
2218 /*
2219  * Channel interface.
2220  */
2221 
2222 /* Create a new, unattached ppp channel. */
2223 int ppp_register_channel(struct ppp_channel *chan)
2224 {
2225         return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2226 }
2227 
2228 /* Create a new, unattached ppp channel for specified net. */
2229 int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2230 {
2231         struct channel *pch;
2232         struct ppp_net *pn;
2233 
2234         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2235         if (!pch)
2236                 return -ENOMEM;
2237 
2238         pn = ppp_pernet(net);
2239 
2240         pch->ppp = NULL;
2241         pch->chan = chan;
2242         pch->chan_net = net;
2243         chan->ppp = pch;
2244         init_ppp_file(&pch->file, CHANNEL);
2245         pch->file.hdrlen = chan->hdrlen;
2246 #ifdef CONFIG_PPP_MULTILINK
2247         pch->lastseq = -1;
2248 #endif /* CONFIG_PPP_MULTILINK */
2249         init_rwsem(&pch->chan_sem);
2250         spin_lock_init(&pch->downl);
2251         rwlock_init(&pch->upl);
2252 
2253         spin_lock_bh(&pn->all_channels_lock);
2254         pch->file.index = ++pn->last_channel_index;
2255         list_add(&pch->list, &pn->new_channels);
2256         atomic_inc(&channel_count);
2257         spin_unlock_bh(&pn->all_channels_lock);
2258 
2259         return 0;
2260 }
2261 
2262 /*
2263  * Return the index of a channel.
2264  */
2265 int ppp_channel_index(struct ppp_channel *chan)
2266 {
2267         struct channel *pch = chan->ppp;
2268 
2269         if (pch)
2270                 return pch->file.index;
2271         return -1;
2272 }
2273 
2274 /*
2275  * Return the PPP unit number to which a channel is connected.
2276  */
2277 int ppp_unit_number(struct ppp_channel *chan)
2278 {
2279         struct channel *pch = chan->ppp;
2280         int unit = -1;
2281 
2282         if (pch) {
2283                 read_lock_bh(&pch->upl);
2284                 if (pch->ppp)
2285                         unit = pch->ppp->file.index;
2286                 read_unlock_bh(&pch->upl);
2287         }
2288         return unit;
2289 }
2290 
2291 /*
2292  * Return the PPP device interface name of a channel.
2293  */
2294 char *ppp_dev_name(struct ppp_channel *chan)
2295 {
2296         struct channel *pch = chan->ppp;
2297         char *name = NULL;
2298 
2299         if (pch) {
2300                 read_lock_bh(&pch->upl);
2301                 if (pch->ppp && pch->ppp->dev)
2302                         name = pch->ppp->dev->name;
2303                 read_unlock_bh(&pch->upl);
2304         }
2305         return name;
2306 }
2307 
2308 
2309 /*
2310  * Disconnect a channel from the generic layer.
2311  * This must be called in process context.
2312  */
2313 void
2314 ppp_unregister_channel(struct ppp_channel *chan)
2315 {
2316         struct channel *pch = chan->ppp;
2317         struct ppp_net *pn;
2318 
2319         if (!pch)
2320                 return;         /* should never happen */
2321 
2322         chan->ppp = NULL;
2323 
2324         /*
2325          * This ensures that we have returned from any calls into the
2326          * the channel's start_xmit or ioctl routine before we proceed.
2327          */
2328         down_write(&pch->chan_sem);
2329         spin_lock_bh(&pch->downl);
2330         pch->chan = NULL;
2331         spin_unlock_bh(&pch->downl);
2332         up_write(&pch->chan_sem);
2333         ppp_disconnect_channel(pch);
2334 
2335         pn = ppp_pernet(pch->chan_net);
2336         spin_lock_bh(&pn->all_channels_lock);
2337         list_del(&pch->list);
2338         spin_unlock_bh(&pn->all_channels_lock);
2339 
2340         pch->file.dead = 1;
2341         wake_up_interruptible(&pch->file.rwait);
2342         if (atomic_dec_and_test(&pch->file.refcnt))
2343                 ppp_destroy_channel(pch);
2344 }
2345 
2346 /*
2347  * Callback from a channel when it can accept more to transmit.
2348  * This should be called at BH/softirq level, not interrupt level.
2349  */
2350 void
2351 ppp_output_wakeup(struct ppp_channel *chan)
2352 {
2353         struct channel *pch = chan->ppp;
2354 
2355         if (!pch)
2356                 return;
2357         ppp_channel_push(pch);
2358 }
2359 
2360 /*
2361  * Compression control.
2362  */
2363 
2364 /* Process the PPPIOCSCOMPRESS ioctl. */
2365 static int
2366 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2367 {
2368         int err;
2369         struct compressor *cp, *ocomp;
2370         struct ppp_option_data data;
2371         void *state, *ostate;
2372         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2373 
2374         err = -EFAULT;
2375         if (copy_from_user(&data, (void __user *) arg, sizeof(data)) ||
2376             (data.length <= CCP_MAX_OPTION_LENGTH &&
2377              copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2378                 goto out;
2379         err = -EINVAL;
2380         if (data.length > CCP_MAX_OPTION_LENGTH ||
2381             ccp_option[1] < 2 || ccp_option[1] > data.length)
2382                 goto out;
2383 
2384         cp = try_then_request_module(
2385                 find_compressor(ccp_option[0]),
2386                 "ppp-compress-%d", ccp_option[0]);
2387         if (!cp)
2388                 goto out;
2389 
2390         err = -ENOBUFS;
2391         if (data.transmit) {
2392                 state = cp->comp_alloc(ccp_option, data.length);
2393                 if (state) {
2394                         ppp_xmit_lock(ppp);
2395                         ppp->xstate &= ~SC_COMP_RUN;
2396                         ocomp = ppp->xcomp;
2397                         ostate = ppp->xc_state;
2398                         ppp->xcomp = cp;
2399                         ppp->xc_state = state;
2400                         ppp_xmit_unlock(ppp);
2401                         if (ostate) {
2402                                 ocomp->comp_free(ostate);
2403                                 module_put(ocomp->owner);
2404                         }
2405                         err = 0;
2406                 } else
2407                         module_put(cp->owner);
2408 
2409         } else {
2410                 state = cp->decomp_alloc(ccp_option, data.length);
2411                 if (state) {
2412                         ppp_recv_lock(ppp);
2413                         ppp->rstate &= ~SC_DECOMP_RUN;
2414                         ocomp = ppp->rcomp;
2415                         ostate = ppp->rc_state;
2416                         ppp->rcomp = cp;
2417                         ppp->rc_state = state;
2418                         ppp_recv_unlock(ppp);
2419                         if (ostate) {
2420                                 ocomp->decomp_free(ostate);
2421                                 module_put(ocomp->owner);
2422                         }
2423                         err = 0;
2424                 } else
2425                         module_put(cp->owner);
2426         }
2427 
2428  out:
2429         return err;
2430 }
2431 
2432 /*
2433  * Look at a CCP packet and update our state accordingly.
2434  * We assume the caller has the xmit or recv path locked.
2435  */
2436 static void
2437 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2438 {
2439         unsigned char *dp;
2440         int len;
2441 
2442         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2443                 return; /* no header */
2444         dp = skb->data + 2;
2445 
2446         switch (CCP_CODE(dp)) {
2447         case CCP_CONFREQ:
2448 
2449                 /* A ConfReq starts negotiation of compression
2450                  * in one direction of transmission,
2451                  * and hence brings it down...but which way?
2452                  *
2453                  * Remember:
2454                  * A ConfReq indicates what the sender would like to receive
2455                  */
2456                 if(inbound)
2457                         /* He is proposing what I should send */
2458                         ppp->xstate &= ~SC_COMP_RUN;
2459                 else
2460                         /* I am proposing to what he should send */
2461                         ppp->rstate &= ~SC_DECOMP_RUN;
2462 
2463                 break;
2464 
2465         case CCP_TERMREQ:
2466         case CCP_TERMACK:
2467                 /*
2468                  * CCP is going down, both directions of transmission
2469                  */
2470                 ppp->rstate &= ~SC_DECOMP_RUN;
2471                 ppp->xstate &= ~SC_COMP_RUN;
2472                 break;
2473 
2474         case CCP_CONFACK:
2475                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2476                         break;
2477                 len = CCP_LENGTH(dp);
2478                 if (!pskb_may_pull(skb, len + 2))
2479                         return;         /* too short */
2480                 dp += CCP_HDRLEN;
2481                 len -= CCP_HDRLEN;
2482                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2483                         break;
2484                 if (inbound) {
2485                         /* we will start receiving compressed packets */
2486                         if (!ppp->rc_state)
2487                                 break;
2488                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2489                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2490                                 ppp->rstate |= SC_DECOMP_RUN;
2491                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2492                         }
2493                 } else {
2494                         /* we will soon start sending compressed packets */
2495                         if (!ppp->xc_state)
2496                                 break;
2497                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2498                                         ppp->file.index, 0, ppp->debug))
2499                                 ppp->xstate |= SC_COMP_RUN;
2500                 }
2501                 break;
2502 
2503         case CCP_RESETACK:
2504                 /* reset the [de]compressor */
2505                 if ((ppp->flags & SC_CCP_UP) == 0)
2506                         break;
2507                 if (inbound) {
2508                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2509                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2510                                 ppp->rstate &= ~SC_DC_ERROR;
2511                         }
2512                 } else {
2513                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2514                                 ppp->xcomp->comp_reset(ppp->xc_state);
2515                 }
2516                 break;
2517         }
2518 }
2519 
2520 /* Free up compression resources. */
2521 static void
2522 ppp_ccp_closed(struct ppp *ppp)
2523 {
2524         void *xstate, *rstate;
2525         struct compressor *xcomp, *rcomp;
2526 
2527         ppp_lock(ppp);
2528         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2529         ppp->xstate = 0;
2530         xcomp = ppp->xcomp;
2531         xstate = ppp->xc_state;
2532         ppp->xc_state = NULL;
2533         ppp->rstate = 0;
2534         rcomp = ppp->rcomp;
2535         rstate = ppp->rc_state;
2536         ppp->rc_state = NULL;
2537         ppp_unlock(ppp);
2538 
2539         if (xstate) {
2540                 xcomp->comp_free(xstate);
2541                 module_put(xcomp->owner);
2542         }
2543         if (rstate) {
2544                 rcomp->decomp_free(rstate);
2545                 module_put(rcomp->owner);
2546         }
2547 }
2548 
2549 /* List of compressors. */
2550 static LIST_HEAD(compressor_list);
2551 static DEFINE_SPINLOCK(compressor_list_lock);
2552 
2553 struct compressor_entry {
2554         struct list_head list;
2555         struct compressor *comp;
2556 };
2557 
2558 static struct compressor_entry *
2559 find_comp_entry(int proto)
2560 {
2561         struct compressor_entry *ce;
2562 
2563         list_for_each_entry(ce, &compressor_list, list) {
2564                 if (ce->comp->compress_proto == proto)
2565                         return ce;
2566         }
2567         return NULL;
2568 }
2569 
2570 /* Register a compressor */
2571 int
2572 ppp_register_compressor(struct compressor *cp)
2573 {
2574         struct compressor_entry *ce;
2575         int ret;
2576         spin_lock(&compressor_list_lock);
2577         ret = -EEXIST;
2578         if (find_comp_entry(cp->compress_proto))
2579                 goto out;
2580         ret = -ENOMEM;
2581         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2582         if (!ce)
2583                 goto out;
2584         ret = 0;
2585         ce->comp = cp;
2586         list_add(&ce->list, &compressor_list);
2587  out:
2588         spin_unlock(&compressor_list_lock);
2589         return ret;
2590 }
2591 
2592 /* Unregister a compressor */
2593 void
2594 ppp_unregister_compressor(struct compressor *cp)
2595 {
2596         struct compressor_entry *ce;
2597 
2598         spin_lock(&compressor_list_lock);
2599         ce = find_comp_entry(cp->compress_proto);
2600         if (ce && ce->comp == cp) {
2601                 list_del(&ce->list);
2602                 kfree(ce);
2603         }
2604         spin_unlock(&compressor_list_lock);
2605 }
2606 
2607 /* Find a compressor. */
2608 static struct compressor *
2609 find_compressor(int type)
2610 {
2611         struct compressor_entry *ce;
2612         struct compressor *cp = NULL;
2613 
2614         spin_lock(&compressor_list_lock);
2615         ce = find_comp_entry(type);
2616         if (ce) {
2617                 cp = ce->comp;
2618                 if (!try_module_get(cp->owner))
2619                         cp = NULL;
2620         }
2621         spin_unlock(&compressor_list_lock);
2622         return cp;
2623 }
2624 
2625 /*
2626  * Miscelleneous stuff.
2627  */
2628 
2629 static void
2630 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2631 {
2632         struct slcompress *vj = ppp->vj;
2633 
2634         memset(st, 0, sizeof(*st));
2635         st->p.ppp_ipackets = ppp->stats64.rx_packets;
2636         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2637         st->p.ppp_ibytes = ppp->stats64.rx_bytes;
2638         st->p.ppp_opackets = ppp->stats64.tx_packets;
2639         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2640         st->p.ppp_obytes = ppp->stats64.tx_bytes;
2641         if (!vj)
2642                 return;
2643         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2644         st->vj.vjs_compressed = vj->sls_o_compressed;
2645         st->vj.vjs_searches = vj->sls_o_searches;
2646         st->vj.vjs_misses = vj->sls_o_misses;
2647         st->vj.vjs_errorin = vj->sls_i_error;
2648         st->vj.vjs_tossed = vj->sls_i_tossed;
2649         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2650         st->vj.vjs_compressedin = vj->sls_i_compressed;
2651 }
2652 
2653 /*
2654  * Stuff for handling the lists of ppp units and channels
2655  * and for initialization.
2656  */
2657 
2658 /*
2659  * Create a new ppp interface unit.  Fails if it can't allocate memory
2660  * or if there is already a unit with the requested number.
2661  * unit == -1 means allocate a new number.
2662  */
2663 static struct ppp *
2664 ppp_create_interface(struct net *net, int unit, int *retp)
2665 {
2666         struct ppp *ppp;
2667         struct ppp_net *pn;
2668         struct net_device *dev = NULL;
2669         int ret = -ENOMEM;
2670         int i;
2671 
2672         dev = alloc_netdev(sizeof(struct ppp), "", ppp_setup);
2673         if (!dev)
2674                 goto out1;
2675 
2676         pn = ppp_pernet(net);
2677 
2678         ppp = netdev_priv(dev);
2679         ppp->dev = dev;
2680         ppp->mru = PPP_MRU;
2681         init_ppp_file(&ppp->file, INTERFACE);
2682         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2683         for (i = 0; i < NUM_NP; ++i)
2684                 ppp->npmode[i] = NPMODE_PASS;
2685         INIT_LIST_HEAD(&ppp->channels);
2686         spin_lock_init(&ppp->rlock);
2687         spin_lock_init(&ppp->wlock);
2688 #ifdef CONFIG_PPP_MULTILINK
2689         ppp->minseq = -1;
2690         skb_queue_head_init(&ppp->mrq);
2691 #endif /* CONFIG_PPP_MULTILINK */
2692 #ifdef CONFIG_PPP_FILTER
2693         ppp->pass_filter = NULL;
2694         ppp->active_filter = NULL;
2695 #endif /* CONFIG_PPP_FILTER */
2696 
2697         /*
2698          * drum roll: don't forget to set
2699          * the net device is belong to
2700          */
2701         dev_net_set(dev, net);
2702 
2703         mutex_lock(&pn->all_ppp_mutex);
2704 
2705         if (unit < 0) {
2706                 unit = unit_get(&pn->units_idr, ppp);
2707                 if (unit < 0) {
2708                         ret = unit;
2709                         goto out2;
2710                 }
2711         } else {
2712                 ret = -EEXIST;
2713                 if (unit_find(&pn->units_idr, unit))
2714                         goto out2; /* unit already exists */
2715                 /*
2716                  * if caller need a specified unit number
2717                  * lets try to satisfy him, otherwise --
2718                  * he should better ask us for new unit number
2719                  *
2720                  * NOTE: yes I know that returning EEXIST it's not
2721                  * fair but at least pppd will ask us to allocate
2722                  * new unit in this case so user is happy :)
2723                  */
2724                 unit = unit_set(&pn->units_idr, ppp, unit);
2725                 if (unit < 0)
2726                         goto out2;
2727         }
2728 
2729         /* Initialize the new ppp unit */
2730         ppp->file.index = unit;
2731         sprintf(dev->name, "ppp%d", unit);
2732 
2733         ret = register_netdev(dev);
2734         if (ret != 0) {
2735                 unit_put(&pn->units_idr, unit);
2736                 netdev_err(ppp->dev, "PPP: couldn't register device %s (%d)\n",
2737                            dev->name, ret);
2738                 goto out2;
2739         }
2740 
2741         ppp->ppp_net = net;
2742 
2743         atomic_inc(&ppp_unit_count);
2744         mutex_unlock(&pn->all_ppp_mutex);
2745 
2746         *retp = 0;
2747         return ppp;
2748 
2749 out2:
2750         mutex_unlock(&pn->all_ppp_mutex);
2751         free_netdev(dev);
2752 out1:
2753         *retp = ret;
2754         return NULL;
2755 }
2756 
2757 /*
2758  * Initialize a ppp_file structure.
2759  */
2760 static void
2761 init_ppp_file(struct ppp_file *pf, int kind)
2762 {
2763         pf->kind = kind;
2764         skb_queue_head_init(&pf->xq);
2765         skb_queue_head_init(&pf->rq);
2766         atomic_set(&pf->refcnt, 1);
2767         init_waitqueue_head(&pf->rwait);
2768 }
2769 
2770 /*
2771  * Take down a ppp interface unit - called when the owning file
2772  * (the one that created the unit) is closed or detached.
2773  */
2774 static void ppp_shutdown_interface(struct ppp *ppp)
2775 {
2776         struct ppp_net *pn;
2777 
2778         pn = ppp_pernet(ppp->ppp_net);
2779         mutex_lock(&pn->all_ppp_mutex);
2780 
2781         /* This will call dev_close() for us. */
2782         ppp_lock(ppp);
2783         if (!ppp->closing) {
2784                 ppp->closing = 1;
2785                 ppp_unlock(ppp);
2786                 unregister_netdev(ppp->dev);
2787                 unit_put(&pn->units_idr, ppp->file.index);
2788         } else
2789                 ppp_unlock(ppp);
2790 
2791         ppp->file.dead = 1;
2792         ppp->owner = NULL;
2793         wake_up_interruptible(&ppp->file.rwait);
2794 
2795         mutex_unlock(&pn->all_ppp_mutex);
2796 }
2797 
2798 /*
2799  * Free the memory used by a ppp unit.  This is only called once
2800  * there are no channels connected to the unit and no file structs
2801  * that reference the unit.
2802  */
2803 static void ppp_destroy_interface(struct ppp *ppp)
2804 {
2805         atomic_dec(&ppp_unit_count);
2806 
2807         if (!ppp->file.dead || ppp->n_channels) {
2808                 /* "can't happen" */
2809                 netdev_err(ppp->dev, "ppp: destroying ppp struct %p "
2810                            "but dead=%d n_channels=%d !\n",
2811                            ppp, ppp->file.dead, ppp->n_channels);
2812                 return;
2813         }
2814 
2815         ppp_ccp_closed(ppp);
2816         if (ppp->vj) {
2817                 slhc_free(ppp->vj);
2818                 ppp->vj = NULL;
2819         }
2820         skb_queue_purge(&ppp->file.xq);
2821         skb_queue_purge(&ppp->file.rq);
2822 #ifdef CONFIG_PPP_MULTILINK
2823         skb_queue_purge(&ppp->mrq);
2824 #endif /* CONFIG_PPP_MULTILINK */
2825 #ifdef CONFIG_PPP_FILTER
2826         if (ppp->pass_filter) {
2827                 sk_unattached_filter_destroy(ppp->pass_filter);
2828                 ppp->pass_filter = NULL;
2829         }
2830 
2831         if (ppp->active_filter) {
2832                 sk_unattached_filter_destroy(ppp->active_filter);
2833                 ppp->active_filter = NULL;
2834         }
2835 #endif /* CONFIG_PPP_FILTER */
2836 
2837         kfree_skb(ppp->xmit_pending);
2838 
2839         free_netdev(ppp->dev);
2840 }
2841 
2842 /*
2843  * Locate an existing ppp unit.
2844  * The caller should have locked the all_ppp_mutex.
2845  */
2846 static struct ppp *
2847 ppp_find_unit(struct ppp_net *pn, int unit)
2848 {
2849         return unit_find(&pn->units_idr, unit);
2850 }
2851 
2852 /*
2853  * Locate an existing ppp channel.
2854  * The caller should have locked the all_channels_lock.
2855  * First we look in the new_channels list, then in the
2856  * all_channels list.  If found in the new_channels list,
2857  * we move it to the all_channels list.  This is for speed
2858  * when we have a lot of channels in use.
2859  */
2860 static struct channel *
2861 ppp_find_channel(struct ppp_net *pn, int unit)
2862 {
2863         struct channel *pch;
2864 
2865         list_for_each_entry(pch, &pn->new_channels, list) {
2866                 if (pch->file.index == unit) {
2867                         list_move(&pch->list, &pn->all_channels);
2868                         return pch;
2869                 }
2870         }
2871 
2872         list_for_each_entry(pch, &pn->all_channels, list) {
2873                 if (pch->file.index == unit)
2874                         return pch;
2875         }
2876 
2877         return NULL;
2878 }
2879 
2880 /*
2881  * Connect a PPP channel to a PPP interface unit.
2882  */
2883 static int
2884 ppp_connect_channel(struct channel *pch, int unit)
2885 {
2886         struct ppp *ppp;
2887         struct ppp_net *pn;
2888         int ret = -ENXIO;
2889         int hdrlen;
2890 
2891         pn = ppp_pernet(pch->chan_net);
2892 
2893         mutex_lock(&pn->all_ppp_mutex);
2894         ppp = ppp_find_unit(pn, unit);
2895         if (!ppp)
2896                 goto out;
2897         write_lock_bh(&pch->upl);
2898         ret = -EINVAL;
2899         if (pch->ppp)
2900                 goto outl;
2901 
2902         ppp_lock(ppp);
2903         if (pch->file.hdrlen > ppp->file.hdrlen)
2904                 ppp->file.hdrlen = pch->file.hdrlen;
2905         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2906         if (hdrlen > ppp->dev->hard_header_len)
2907                 ppp->dev->hard_header_len = hdrlen;
2908         list_add_tail(&pch->clist, &ppp->channels);
2909         ++ppp->n_channels;
2910         pch->ppp = ppp;
2911         atomic_inc(&ppp->file.refcnt);
2912         ppp_unlock(ppp);
2913         ret = 0;
2914 
2915  outl:
2916         write_unlock_bh(&pch->upl);
2917  out:
2918         mutex_unlock(&pn->all_ppp_mutex);
2919         return ret;
2920 }
2921 
2922 /*
2923  * Disconnect a channel from its ppp unit.
2924  */
2925 static int
2926 ppp_disconnect_channel(struct channel *pch)
2927 {
2928         struct ppp *ppp;
2929         int err = -EINVAL;
2930 
2931         write_lock_bh(&pch->upl);
2932         ppp = pch->ppp;
2933         pch->ppp = NULL;
2934         write_unlock_bh(&pch->upl);
2935         if (ppp) {
2936                 /* remove it from the ppp unit's list */
2937                 ppp_lock(ppp);
2938                 list_del(&pch->clist);
2939                 if (--ppp->n_channels == 0)
2940                         wake_up_interruptible(&ppp->file.rwait);
2941                 ppp_unlock(ppp);
2942                 if (atomic_dec_and_test(&ppp->file.refcnt))
2943                         ppp_destroy_interface(ppp);
2944                 err = 0;
2945         }
2946         return err;
2947 }
2948 
2949 /*
2950  * Free up the resources used by a ppp channel.
2951  */
2952 static void ppp_destroy_channel(struct channel *pch)
2953 {
2954         atomic_dec(&channel_count);
2955 
2956         if (!pch->file.dead) {
2957                 /* "can't happen" */
2958                 pr_err("ppp: destroying undead channel %p !\n", pch);
2959                 return;
2960         }
2961         skb_queue_purge(&pch->file.xq);
2962         skb_queue_purge(&pch->file.rq);
2963         kfree(pch);
2964 }
2965 
2966 static void __exit ppp_cleanup(void)
2967 {
2968         /* should never happen */
2969         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2970                 pr_err("PPP: removing module but units remain!\n");
2971         unregister_chrdev(PPP_MAJOR, "ppp");
2972         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2973         class_destroy(ppp_class);
2974         unregister_pernet_device(&ppp_net_ops);
2975 }
2976 
2977 /*
2978  * Units handling. Caller must protect concurrent access
2979  * by holding all_ppp_mutex
2980  */
2981 
2982 /* associate pointer with specified number */
2983 static int unit_set(struct idr *p, void *ptr, int n)
2984 {
2985         int unit;
2986 
2987         unit = idr_alloc(p, ptr, n, n + 1, GFP_KERNEL);
2988         if (unit == -ENOSPC)
2989                 unit = -EINVAL;
2990         return unit;
2991 }
2992 
2993 /* get new free unit number and associate pointer with it */
2994 static int unit_get(struct idr *p, void *ptr)
2995 {
2996         return idr_alloc(p, ptr, 0, 0, GFP_KERNEL);
2997 }
2998 
2999 /* put unit number back to a pool */
3000 static void unit_put(struct idr *p, int n)
3001 {
3002         idr_remove(p, n);
3003 }
3004 
3005 /* get pointer associated with the number */
3006 static void *unit_find(struct idr *p, int n)
3007 {
3008         return idr_find(p, n);
3009 }
3010 
3011 /* Module/initialization stuff */
3012 
3013 module_init(ppp_init);
3014 module_exit(ppp_cleanup);
3015 
3016 EXPORT_SYMBOL(ppp_register_net_channel);
3017 EXPORT_SYMBOL(ppp_register_channel);
3018 EXPORT_SYMBOL(ppp_unregister_channel);
3019 EXPORT_SYMBOL(ppp_channel_index);
3020 EXPORT_SYMBOL(ppp_unit_number);
3021 EXPORT_SYMBOL(ppp_dev_name);
3022 EXPORT_SYMBOL(ppp_input);
3023 EXPORT_SYMBOL(ppp_input_error);
3024 EXPORT_SYMBOL(ppp_output_wakeup);
3025 EXPORT_SYMBOL(ppp_register_compressor);
3026 EXPORT_SYMBOL(ppp_unregister_compressor);
3027 MODULE_LICENSE("GPL");
3028 MODULE_ALIAS_CHARDEV(PPP_MAJOR, 0);
3029 MODULE_ALIAS("devname:ppp");
3030 

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