Version:  2.0.40 2.2.26 2.4.37 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5

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 bpf_prog *pass_filter;   /* filter for packets to pass */
147         struct bpf_prog *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,
273                                         struct file *file, int *retp);
274 static void init_ppp_file(struct ppp_file *pf, int kind);
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 const struct net_device_ops ppp_netdev_ops;
287 
288 static struct class *ppp_class;
289 
290 /* per net-namespace data */
291 static inline struct ppp_net *ppp_pernet(struct net *net)
292 {
293         BUG_ON(!net);
294 
295         return net_generic(net, ppp_net_id);
296 }
297 
298 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
299 static inline int proto_to_npindex(int proto)
300 {
301         switch (proto) {
302         case PPP_IP:
303                 return NP_IP;
304         case PPP_IPV6:
305                 return NP_IPV6;
306         case PPP_IPX:
307                 return NP_IPX;
308         case PPP_AT:
309                 return NP_AT;
310         case PPP_MPLS_UC:
311                 return NP_MPLS_UC;
312         case PPP_MPLS_MC:
313                 return NP_MPLS_MC;
314         }
315         return -EINVAL;
316 }
317 
318 /* Translates an NP index into a PPP protocol number */
319 static const int npindex_to_proto[NUM_NP] = {
320         PPP_IP,
321         PPP_IPV6,
322         PPP_IPX,
323         PPP_AT,
324         PPP_MPLS_UC,
325         PPP_MPLS_MC,
326 };
327 
328 /* Translates an ethertype into an NP index */
329 static inline int ethertype_to_npindex(int ethertype)
330 {
331         switch (ethertype) {
332         case ETH_P_IP:
333                 return NP_IP;
334         case ETH_P_IPV6:
335                 return NP_IPV6;
336         case ETH_P_IPX:
337                 return NP_IPX;
338         case ETH_P_PPPTALK:
339         case ETH_P_ATALK:
340                 return NP_AT;
341         case ETH_P_MPLS_UC:
342                 return NP_MPLS_UC;
343         case ETH_P_MPLS_MC:
344                 return NP_MPLS_MC;
345         }
346         return -1;
347 }
348 
349 /* Translates an NP index into an ethertype */
350 static const int npindex_to_ethertype[NUM_NP] = {
351         ETH_P_IP,
352         ETH_P_IPV6,
353         ETH_P_IPX,
354         ETH_P_PPPTALK,
355         ETH_P_MPLS_UC,
356         ETH_P_MPLS_MC,
357 };
358 
359 /*
360  * Locking shorthand.
361  */
362 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
363 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
364 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
365 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
366 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
367                                      ppp_recv_lock(ppp); } while (0)
368 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
369                                      ppp_xmit_unlock(ppp); } while (0)
370 
371 /*
372  * /dev/ppp device routines.
373  * The /dev/ppp device is used by pppd to control the ppp unit.
374  * It supports the read, write, ioctl and poll functions.
375  * Open instances of /dev/ppp can be in one of three states:
376  * unattached, attached to a ppp unit, or attached to a ppp channel.
377  */
378 static int ppp_open(struct inode *inode, struct file *file)
379 {
380         /*
381          * This could (should?) be enforced by the permissions on /dev/ppp.
382          */
383         if (!capable(CAP_NET_ADMIN))
384                 return -EPERM;
385         return 0;
386 }
387 
388 static int ppp_release(struct inode *unused, struct file *file)
389 {
390         struct ppp_file *pf = file->private_data;
391         struct ppp *ppp;
392 
393         if (pf) {
394                 file->private_data = NULL;
395                 if (pf->kind == INTERFACE) {
396                         ppp = PF_TO_PPP(pf);
397                         rtnl_lock();
398                         if (file == ppp->owner)
399                                 unregister_netdevice(ppp->dev);
400                         rtnl_unlock();
401                 }
402                 if (atomic_dec_and_test(&pf->refcnt)) {
403                         switch (pf->kind) {
404                         case INTERFACE:
405                                 ppp_destroy_interface(PF_TO_PPP(pf));
406                                 break;
407                         case CHANNEL:
408                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
409                                 break;
410                         }
411                 }
412         }
413         return 0;
414 }
415 
416 static ssize_t ppp_read(struct file *file, char __user *buf,
417                         size_t count, loff_t *ppos)
418 {
419         struct ppp_file *pf = file->private_data;
420         DECLARE_WAITQUEUE(wait, current);
421         ssize_t ret;
422         struct sk_buff *skb = NULL;
423         struct iovec iov;
424         struct iov_iter to;
425 
426         ret = count;
427 
428         if (!pf)
429                 return -ENXIO;
430         add_wait_queue(&pf->rwait, &wait);
431         for (;;) {
432                 set_current_state(TASK_INTERRUPTIBLE);
433                 skb = skb_dequeue(&pf->rq);
434                 if (skb)
435                         break;
436                 ret = 0;
437                 if (pf->dead)
438                         break;
439                 if (pf->kind == INTERFACE) {
440                         /*
441                          * Return 0 (EOF) on an interface that has no
442                          * channels connected, unless it is looping
443                          * network traffic (demand mode).
444                          */
445                         struct ppp *ppp = PF_TO_PPP(pf);
446 
447                         ppp_recv_lock(ppp);
448                         if (ppp->n_channels == 0 &&
449                             (ppp->flags & SC_LOOP_TRAFFIC) == 0) {
450                                 ppp_recv_unlock(ppp);
451                                 break;
452                         }
453                         ppp_recv_unlock(ppp);
454                 }
455                 ret = -EAGAIN;
456                 if (file->f_flags & O_NONBLOCK)
457                         break;
458                 ret = -ERESTARTSYS;
459                 if (signal_pending(current))
460                         break;
461                 schedule();
462         }
463         set_current_state(TASK_RUNNING);
464         remove_wait_queue(&pf->rwait, &wait);
465 
466         if (!skb)
467                 goto out;
468 
469         ret = -EOVERFLOW;
470         if (skb->len > count)
471                 goto outf;
472         ret = -EFAULT;
473         iov.iov_base = buf;
474         iov.iov_len = count;
475         iov_iter_init(&to, READ, &iov, 1, count);
476         if (skb_copy_datagram_iter(skb, 0, &to, skb->len))
477                 goto outf;
478         ret = skb->len;
479 
480  outf:
481         kfree_skb(skb);
482  out:
483         return ret;
484 }
485 
486 static ssize_t ppp_write(struct file *file, const char __user *buf,
487                          size_t count, loff_t *ppos)
488 {
489         struct ppp_file *pf = file->private_data;
490         struct sk_buff *skb;
491         ssize_t ret;
492 
493         if (!pf)
494                 return -ENXIO;
495         ret = -ENOMEM;
496         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
497         if (!skb)
498                 goto out;
499         skb_reserve(skb, pf->hdrlen);
500         ret = -EFAULT;
501         if (copy_from_user(skb_put(skb, count), buf, count)) {
502                 kfree_skb(skb);
503                 goto out;
504         }
505 
506         skb_queue_tail(&pf->xq, skb);
507 
508         switch (pf->kind) {
509         case INTERFACE:
510                 ppp_xmit_process(PF_TO_PPP(pf));
511                 break;
512         case CHANNEL:
513                 ppp_channel_push(PF_TO_CHANNEL(pf));
514                 break;
515         }
516 
517         ret = count;
518 
519  out:
520         return ret;
521 }
522 
523 /* No kernel lock - fine */
524 static unsigned int ppp_poll(struct file *file, poll_table *wait)
525 {
526         struct ppp_file *pf = file->private_data;
527         unsigned int mask;
528 
529         if (!pf)
530                 return 0;
531         poll_wait(file, &pf->rwait, wait);
532         mask = POLLOUT | POLLWRNORM;
533         if (skb_peek(&pf->rq))
534                 mask |= POLLIN | POLLRDNORM;
535         if (pf->dead)
536                 mask |= POLLHUP;
537         else if (pf->kind == INTERFACE) {
538                 /* see comment in ppp_read */
539                 struct ppp *ppp = PF_TO_PPP(pf);
540 
541                 ppp_recv_lock(ppp);
542                 if (ppp->n_channels == 0 &&
543                     (ppp->flags & SC_LOOP_TRAFFIC) == 0)
544                         mask |= POLLIN | POLLRDNORM;
545                 ppp_recv_unlock(ppp);
546         }
547 
548         return mask;
549 }
550 
551 #ifdef CONFIG_PPP_FILTER
552 static int get_filter(void __user *arg, struct sock_filter **p)
553 {
554         struct sock_fprog uprog;
555         struct sock_filter *code = NULL;
556         int len;
557 
558         if (copy_from_user(&uprog, arg, sizeof(uprog)))
559                 return -EFAULT;
560 
561         if (!uprog.len) {
562                 *p = NULL;
563                 return 0;
564         }
565 
566         len = uprog.len * sizeof(struct sock_filter);
567         code = memdup_user(uprog.filter, len);
568         if (IS_ERR(code))
569                 return PTR_ERR(code);
570 
571         *p = code;
572         return uprog.len;
573 }
574 #endif /* CONFIG_PPP_FILTER */
575 
576 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
577 {
578         struct ppp_file *pf = file->private_data;
579         struct ppp *ppp;
580         int err = -EFAULT, val, val2, i;
581         struct ppp_idle idle;
582         struct npioctl npi;
583         int unit, cflags;
584         struct slcompress *vj;
585         void __user *argp = (void __user *)arg;
586         int __user *p = argp;
587 
588         if (!pf)
589                 return ppp_unattached_ioctl(current->nsproxy->net_ns,
590                                         pf, file, cmd, arg);
591 
592         if (cmd == PPPIOCDETACH) {
593                 /*
594                  * We have to be careful here... if the file descriptor
595                  * has been dup'd, we could have another process in the
596                  * middle of a poll using the same file *, so we had
597                  * better not free the interface data structures -
598                  * instead we fail the ioctl.  Even in this case, we
599                  * shut down the interface if we are the owner of it.
600                  * Actually, we should get rid of PPPIOCDETACH, userland
601                  * (i.e. pppd) could achieve the same effect by closing
602                  * this fd and reopening /dev/ppp.
603                  */
604                 err = -EINVAL;
605                 mutex_lock(&ppp_mutex);
606                 if (pf->kind == INTERFACE) {
607                         ppp = PF_TO_PPP(pf);
608                         rtnl_lock();
609                         if (file == ppp->owner)
610                                 unregister_netdevice(ppp->dev);
611                         rtnl_unlock();
612                 }
613                 if (atomic_long_read(&file->f_count) < 2) {
614                         ppp_release(NULL, file);
615                         err = 0;
616                 } else
617                         pr_warn("PPPIOCDETACH file->f_count=%ld\n",
618                                 atomic_long_read(&file->f_count));
619                 mutex_unlock(&ppp_mutex);
620                 return err;
621         }
622 
623         if (pf->kind == CHANNEL) {
624                 struct channel *pch;
625                 struct ppp_channel *chan;
626 
627                 mutex_lock(&ppp_mutex);
628                 pch = PF_TO_CHANNEL(pf);
629 
630                 switch (cmd) {
631                 case PPPIOCCONNECT:
632                         if (get_user(unit, p))
633                                 break;
634                         err = ppp_connect_channel(pch, unit);
635                         break;
636 
637                 case PPPIOCDISCONN:
638                         err = ppp_disconnect_channel(pch);
639                         break;
640 
641                 default:
642                         down_read(&pch->chan_sem);
643                         chan = pch->chan;
644                         err = -ENOTTY;
645                         if (chan && chan->ops->ioctl)
646                                 err = chan->ops->ioctl(chan, cmd, arg);
647                         up_read(&pch->chan_sem);
648                 }
649                 mutex_unlock(&ppp_mutex);
650                 return err;
651         }
652 
653         if (pf->kind != INTERFACE) {
654                 /* can't happen */
655                 pr_err("PPP: not interface or channel??\n");
656                 return -EINVAL;
657         }
658 
659         mutex_lock(&ppp_mutex);
660         ppp = PF_TO_PPP(pf);
661         switch (cmd) {
662         case PPPIOCSMRU:
663                 if (get_user(val, p))
664                         break;
665                 ppp->mru = val;
666                 err = 0;
667                 break;
668 
669         case PPPIOCSFLAGS:
670                 if (get_user(val, p))
671                         break;
672                 ppp_lock(ppp);
673                 cflags = ppp->flags & ~val;
674 #ifdef CONFIG_PPP_MULTILINK
675                 if (!(ppp->flags & SC_MULTILINK) && (val & SC_MULTILINK))
676                         ppp->nextseq = 0;
677 #endif
678                 ppp->flags = val & SC_FLAG_BITS;
679                 ppp_unlock(ppp);
680                 if (cflags & SC_CCP_OPEN)
681                         ppp_ccp_closed(ppp);
682                 err = 0;
683                 break;
684 
685         case PPPIOCGFLAGS:
686                 val = ppp->flags | ppp->xstate | ppp->rstate;
687                 if (put_user(val, p))
688                         break;
689                 err = 0;
690                 break;
691 
692         case PPPIOCSCOMPRESS:
693                 err = ppp_set_compress(ppp, arg);
694                 break;
695 
696         case PPPIOCGUNIT:
697                 if (put_user(ppp->file.index, p))
698                         break;
699                 err = 0;
700                 break;
701 
702         case PPPIOCSDEBUG:
703                 if (get_user(val, p))
704                         break;
705                 ppp->debug = val;
706                 err = 0;
707                 break;
708 
709         case PPPIOCGDEBUG:
710                 if (put_user(ppp->debug, p))
711                         break;
712                 err = 0;
713                 break;
714 
715         case PPPIOCGIDLE:
716                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
717                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
718                 if (copy_to_user(argp, &idle, sizeof(idle)))
719                         break;
720                 err = 0;
721                 break;
722 
723         case PPPIOCSMAXCID:
724                 if (get_user(val, p))
725                         break;
726                 val2 = 15;
727                 if ((val >> 16) != 0) {
728                         val2 = val >> 16;
729                         val &= 0xffff;
730                 }
731                 vj = slhc_init(val2+1, val+1);
732                 if (IS_ERR(vj)) {
733                         err = PTR_ERR(vj);
734                         break;
735                 }
736                 ppp_lock(ppp);
737                 if (ppp->vj)
738                         slhc_free(ppp->vj);
739                 ppp->vj = vj;
740                 ppp_unlock(ppp);
741                 err = 0;
742                 break;
743 
744         case PPPIOCGNPMODE:
745         case PPPIOCSNPMODE:
746                 if (copy_from_user(&npi, argp, sizeof(npi)))
747                         break;
748                 err = proto_to_npindex(npi.protocol);
749                 if (err < 0)
750                         break;
751                 i = err;
752                 if (cmd == PPPIOCGNPMODE) {
753                         err = -EFAULT;
754                         npi.mode = ppp->npmode[i];
755                         if (copy_to_user(argp, &npi, sizeof(npi)))
756                                 break;
757                 } else {
758                         ppp->npmode[i] = npi.mode;
759                         /* we may be able to transmit more packets now (??) */
760                         netif_wake_queue(ppp->dev);
761                 }
762                 err = 0;
763                 break;
764 
765 #ifdef CONFIG_PPP_FILTER
766         case PPPIOCSPASS:
767         {
768                 struct sock_filter *code;
769 
770                 err = get_filter(argp, &code);
771                 if (err >= 0) {
772                         struct bpf_prog *pass_filter = NULL;
773                         struct sock_fprog_kern fprog = {
774                                 .len = err,
775                                 .filter = code,
776                         };
777 
778                         err = 0;
779                         if (fprog.filter)
780                                 err = bpf_prog_create(&pass_filter, &fprog);
781                         if (!err) {
782                                 ppp_lock(ppp);
783                                 if (ppp->pass_filter)
784                                         bpf_prog_destroy(ppp->pass_filter);
785                                 ppp->pass_filter = pass_filter;
786                                 ppp_unlock(ppp);
787                         }
788                         kfree(code);
789                 }
790                 break;
791         }
792         case PPPIOCSACTIVE:
793         {
794                 struct sock_filter *code;
795 
796                 err = get_filter(argp, &code);
797                 if (err >= 0) {
798                         struct bpf_prog *active_filter = NULL;
799                         struct sock_fprog_kern fprog = {
800                                 .len = err,
801                                 .filter = code,
802                         };
803 
804                         err = 0;
805                         if (fprog.filter)
806                                 err = bpf_prog_create(&active_filter, &fprog);
807                         if (!err) {
808                                 ppp_lock(ppp);
809                                 if (ppp->active_filter)
810                                         bpf_prog_destroy(ppp->active_filter);
811                                 ppp->active_filter = active_filter;
812                                 ppp_unlock(ppp);
813                         }
814                         kfree(code);
815                 }
816                 break;
817         }
818 #endif /* CONFIG_PPP_FILTER */
819 
820 #ifdef CONFIG_PPP_MULTILINK
821         case PPPIOCSMRRU:
822                 if (get_user(val, p))
823                         break;
824                 ppp_recv_lock(ppp);
825                 ppp->mrru = val;
826                 ppp_recv_unlock(ppp);
827                 err = 0;
828                 break;
829 #endif /* CONFIG_PPP_MULTILINK */
830 
831         default:
832                 err = -ENOTTY;
833         }
834         mutex_unlock(&ppp_mutex);
835         return err;
836 }
837 
838 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
839                         struct file *file, unsigned int cmd, unsigned long arg)
840 {
841         int unit, err = -EFAULT;
842         struct ppp *ppp;
843         struct channel *chan;
844         struct ppp_net *pn;
845         int __user *p = (int __user *)arg;
846 
847         mutex_lock(&ppp_mutex);
848         switch (cmd) {
849         case PPPIOCNEWUNIT:
850                 /* Create a new ppp unit */
851                 if (get_user(unit, p))
852                         break;
853                 ppp = ppp_create_interface(net, unit, file, &err);
854                 if (!ppp)
855                         break;
856                 file->private_data = &ppp->file;
857                 err = -EFAULT;
858                 if (put_user(ppp->file.index, p))
859                         break;
860                 err = 0;
861                 break;
862 
863         case PPPIOCATTACH:
864                 /* Attach to an existing ppp unit */
865                 if (get_user(unit, p))
866                         break;
867                 err = -ENXIO;
868                 pn = ppp_pernet(net);
869                 mutex_lock(&pn->all_ppp_mutex);
870                 ppp = ppp_find_unit(pn, unit);
871                 if (ppp) {
872                         atomic_inc(&ppp->file.refcnt);
873                         file->private_data = &ppp->file;
874                         err = 0;
875                 }
876                 mutex_unlock(&pn->all_ppp_mutex);
877                 break;
878 
879         case PPPIOCATTCHAN:
880                 if (get_user(unit, p))
881                         break;
882                 err = -ENXIO;
883                 pn = ppp_pernet(net);
884                 spin_lock_bh(&pn->all_channels_lock);
885                 chan = ppp_find_channel(pn, unit);
886                 if (chan) {
887                         atomic_inc(&chan->file.refcnt);
888                         file->private_data = &chan->file;
889                         err = 0;
890                 }
891                 spin_unlock_bh(&pn->all_channels_lock);
892                 break;
893 
894         default:
895                 err = -ENOTTY;
896         }
897         mutex_unlock(&ppp_mutex);
898         return err;
899 }
900 
901 static const struct file_operations ppp_device_fops = {
902         .owner          = THIS_MODULE,
903         .read           = ppp_read,
904         .write          = ppp_write,
905         .poll           = ppp_poll,
906         .unlocked_ioctl = ppp_ioctl,
907         .open           = ppp_open,
908         .release        = ppp_release,
909         .llseek         = noop_llseek,
910 };
911 
912 static __net_init int ppp_init_net(struct net *net)
913 {
914         struct ppp_net *pn = net_generic(net, ppp_net_id);
915 
916         idr_init(&pn->units_idr);
917         mutex_init(&pn->all_ppp_mutex);
918 
919         INIT_LIST_HEAD(&pn->all_channels);
920         INIT_LIST_HEAD(&pn->new_channels);
921 
922         spin_lock_init(&pn->all_channels_lock);
923 
924         return 0;
925 }
926 
927 static __net_exit void ppp_exit_net(struct net *net)
928 {
929         struct ppp_net *pn = net_generic(net, ppp_net_id);
930         struct net_device *dev;
931         struct net_device *aux;
932         struct ppp *ppp;
933         LIST_HEAD(list);
934         int id;
935 
936         rtnl_lock();
937         for_each_netdev_safe(net, dev, aux) {
938                 if (dev->netdev_ops == &ppp_netdev_ops)
939                         unregister_netdevice_queue(dev, &list);
940         }
941 
942         idr_for_each_entry(&pn->units_idr, ppp, id)
943                 /* Skip devices already unregistered by previous loop */
944                 if (!net_eq(dev_net(ppp->dev), net))
945                         unregister_netdevice_queue(ppp->dev, &list);
946 
947         unregister_netdevice_many(&list);
948         rtnl_unlock();
949 
950         idr_destroy(&pn->units_idr);
951 }
952 
953 static struct pernet_operations ppp_net_ops = {
954         .init = ppp_init_net,
955         .exit = ppp_exit_net,
956         .id   = &ppp_net_id,
957         .size = sizeof(struct ppp_net),
958 };
959 
960 #define PPP_MAJOR       108
961 
962 /* Called at boot time if ppp is compiled into the kernel,
963    or at module load time (from init_module) if compiled as a module. */
964 static int __init ppp_init(void)
965 {
966         int err;
967 
968         pr_info("PPP generic driver version " PPP_VERSION "\n");
969 
970         err = register_pernet_device(&ppp_net_ops);
971         if (err) {
972                 pr_err("failed to register PPP pernet device (%d)\n", err);
973                 goto out;
974         }
975 
976         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
977         if (err) {
978                 pr_err("failed to register PPP device (%d)\n", err);
979                 goto out_net;
980         }
981 
982         ppp_class = class_create(THIS_MODULE, "ppp");
983         if (IS_ERR(ppp_class)) {
984                 err = PTR_ERR(ppp_class);
985                 goto out_chrdev;
986         }
987 
988         /* not a big deal if we fail here :-) */
989         device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
990 
991         return 0;
992 
993 out_chrdev:
994         unregister_chrdev(PPP_MAJOR, "ppp");
995 out_net:
996         unregister_pernet_device(&ppp_net_ops);
997 out:
998         return err;
999 }
1000 
1001 /*
1002  * Network interface unit routines.
1003  */
1004 static netdev_tx_t
1005 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
1006 {
1007         struct ppp *ppp = netdev_priv(dev);
1008         int npi, proto;
1009         unsigned char *pp;
1010 
1011         npi = ethertype_to_npindex(ntohs(skb->protocol));
1012         if (npi < 0)
1013                 goto outf;
1014 
1015         /* Drop, accept or reject the packet */
1016         switch (ppp->npmode[npi]) {
1017         case NPMODE_PASS:
1018                 break;
1019         case NPMODE_QUEUE:
1020                 /* it would be nice to have a way to tell the network
1021                    system to queue this one up for later. */
1022                 goto outf;
1023         case NPMODE_DROP:
1024         case NPMODE_ERROR:
1025                 goto outf;
1026         }
1027 
1028         /* Put the 2-byte PPP protocol number on the front,
1029            making sure there is room for the address and control fields. */
1030         if (skb_cow_head(skb, PPP_HDRLEN))
1031                 goto outf;
1032 
1033         pp = skb_push(skb, 2);
1034         proto = npindex_to_proto[npi];
1035         put_unaligned_be16(proto, pp);
1036 
1037         skb_scrub_packet(skb, !net_eq(ppp->ppp_net, dev_net(dev)));
1038         skb_queue_tail(&ppp->file.xq, skb);
1039         ppp_xmit_process(ppp);
1040         return NETDEV_TX_OK;
1041 
1042  outf:
1043         kfree_skb(skb);
1044         ++dev->stats.tx_dropped;
1045         return NETDEV_TX_OK;
1046 }
1047 
1048 static int
1049 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
1050 {
1051         struct ppp *ppp = netdev_priv(dev);
1052         int err = -EFAULT;
1053         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
1054         struct ppp_stats stats;
1055         struct ppp_comp_stats cstats;
1056         char *vers;
1057 
1058         switch (cmd) {
1059         case SIOCGPPPSTATS:
1060                 ppp_get_stats(ppp, &stats);
1061                 if (copy_to_user(addr, &stats, sizeof(stats)))
1062                         break;
1063                 err = 0;
1064                 break;
1065 
1066         case SIOCGPPPCSTATS:
1067                 memset(&cstats, 0, sizeof(cstats));
1068                 if (ppp->xc_state)
1069                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
1070                 if (ppp->rc_state)
1071                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
1072                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
1073                         break;
1074                 err = 0;
1075                 break;
1076 
1077         case SIOCGPPPVER:
1078                 vers = PPP_VERSION;
1079                 if (copy_to_user(addr, vers, strlen(vers) + 1))
1080                         break;
1081                 err = 0;
1082                 break;
1083 
1084         default:
1085                 err = -EINVAL;
1086         }
1087 
1088         return err;
1089 }
1090 
1091 static struct rtnl_link_stats64*
1092 ppp_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats64)
1093 {
1094         struct ppp *ppp = netdev_priv(dev);
1095 
1096         ppp_recv_lock(ppp);
1097         stats64->rx_packets = ppp->stats64.rx_packets;
1098         stats64->rx_bytes   = ppp->stats64.rx_bytes;
1099         ppp_recv_unlock(ppp);
1100 
1101         ppp_xmit_lock(ppp);
1102         stats64->tx_packets = ppp->stats64.tx_packets;
1103         stats64->tx_bytes   = ppp->stats64.tx_bytes;
1104         ppp_xmit_unlock(ppp);
1105 
1106         stats64->rx_errors        = dev->stats.rx_errors;
1107         stats64->tx_errors        = dev->stats.tx_errors;
1108         stats64->rx_dropped       = dev->stats.rx_dropped;
1109         stats64->tx_dropped       = dev->stats.tx_dropped;
1110         stats64->rx_length_errors = dev->stats.rx_length_errors;
1111 
1112         return stats64;
1113 }
1114 
1115 static struct lock_class_key ppp_tx_busylock;
1116 static int ppp_dev_init(struct net_device *dev)
1117 {
1118         dev->qdisc_tx_busylock = &ppp_tx_busylock;
1119         return 0;
1120 }
1121 
1122 static void ppp_dev_uninit(struct net_device *dev)
1123 {
1124         struct ppp *ppp = netdev_priv(dev);
1125         struct ppp_net *pn = ppp_pernet(ppp->ppp_net);
1126 
1127         ppp_lock(ppp);
1128         ppp->closing = 1;
1129         ppp_unlock(ppp);
1130 
1131         mutex_lock(&pn->all_ppp_mutex);
1132         unit_put(&pn->units_idr, ppp->file.index);
1133         mutex_unlock(&pn->all_ppp_mutex);
1134 
1135         ppp->owner = NULL;
1136 
1137         ppp->file.dead = 1;
1138         wake_up_interruptible(&ppp->file.rwait);
1139 }
1140 
1141 static const struct net_device_ops ppp_netdev_ops = {
1142         .ndo_init        = ppp_dev_init,
1143         .ndo_uninit      = ppp_dev_uninit,
1144         .ndo_start_xmit  = ppp_start_xmit,
1145         .ndo_do_ioctl    = ppp_net_ioctl,
1146         .ndo_get_stats64 = ppp_get_stats64,
1147 };
1148 
1149 static struct device_type ppp_type = {
1150         .name = "ppp",
1151 };
1152 
1153 static void ppp_setup(struct net_device *dev)
1154 {
1155         dev->netdev_ops = &ppp_netdev_ops;
1156         SET_NETDEV_DEVTYPE(dev, &ppp_type);
1157 
1158         dev->hard_header_len = PPP_HDRLEN;
1159         dev->mtu = PPP_MRU;
1160         dev->addr_len = 0;
1161         dev->tx_queue_len = 3;
1162         dev->type = ARPHRD_PPP;
1163         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1164         netif_keep_dst(dev);
1165 }
1166 
1167 /*
1168  * Transmit-side routines.
1169  */
1170 
1171 /*
1172  * Called to do any work queued up on the transmit side
1173  * that can now be done.
1174  */
1175 static void
1176 ppp_xmit_process(struct ppp *ppp)
1177 {
1178         struct sk_buff *skb;
1179 
1180         ppp_xmit_lock(ppp);
1181         if (!ppp->closing) {
1182                 ppp_push(ppp);
1183                 while (!ppp->xmit_pending &&
1184                        (skb = skb_dequeue(&ppp->file.xq)))
1185                         ppp_send_frame(ppp, skb);
1186                 /* If there's no work left to do, tell the core net
1187                    code that we can accept some more. */
1188                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1189                         netif_wake_queue(ppp->dev);
1190                 else
1191                         netif_stop_queue(ppp->dev);
1192         }
1193         ppp_xmit_unlock(ppp);
1194 }
1195 
1196 static inline struct sk_buff *
1197 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1198 {
1199         struct sk_buff *new_skb;
1200         int len;
1201         int new_skb_size = ppp->dev->mtu +
1202                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1203         int compressor_skb_size = ppp->dev->mtu +
1204                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1205         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1206         if (!new_skb) {
1207                 if (net_ratelimit())
1208                         netdev_err(ppp->dev, "PPP: no memory (comp pkt)\n");
1209                 return NULL;
1210         }
1211         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1212                 skb_reserve(new_skb,
1213                             ppp->dev->hard_header_len - PPP_HDRLEN);
1214 
1215         /* compressor still expects A/C bytes in hdr */
1216         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1217                                    new_skb->data, skb->len + 2,
1218                                    compressor_skb_size);
1219         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1220                 consume_skb(skb);
1221                 skb = new_skb;
1222                 skb_put(skb, len);
1223                 skb_pull(skb, 2);       /* pull off A/C bytes */
1224         } else if (len == 0) {
1225                 /* didn't compress, or CCP not up yet */
1226                 consume_skb(new_skb);
1227                 new_skb = skb;
1228         } else {
1229                 /*
1230                  * (len < 0)
1231                  * MPPE requires that we do not send unencrypted
1232                  * frames.  The compressor will return -1 if we
1233                  * should drop the frame.  We cannot simply test
1234                  * the compress_proto because MPPE and MPPC share
1235                  * the same number.
1236                  */
1237                 if (net_ratelimit())
1238                         netdev_err(ppp->dev, "ppp: compressor dropped pkt\n");
1239                 kfree_skb(skb);
1240                 consume_skb(new_skb);
1241                 new_skb = NULL;
1242         }
1243         return new_skb;
1244 }
1245 
1246 /*
1247  * Compress and send a frame.
1248  * The caller should have locked the xmit path,
1249  * and xmit_pending should be 0.
1250  */
1251 static void
1252 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1253 {
1254         int proto = PPP_PROTO(skb);
1255         struct sk_buff *new_skb;
1256         int len;
1257         unsigned char *cp;
1258 
1259         if (proto < 0x8000) {
1260 #ifdef CONFIG_PPP_FILTER
1261                 /* check if we should pass this packet */
1262                 /* the filter instructions are constructed assuming
1263                    a four-byte PPP header on each packet */
1264                 *skb_push(skb, 2) = 1;
1265                 if (ppp->pass_filter &&
1266                     BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
1267                         if (ppp->debug & 1)
1268                                 netdev_printk(KERN_DEBUG, ppp->dev,
1269                                               "PPP: outbound frame "
1270                                               "not passed\n");
1271                         kfree_skb(skb);
1272                         return;
1273                 }
1274                 /* if this packet passes the active filter, record the time */
1275                 if (!(ppp->active_filter &&
1276                       BPF_PROG_RUN(ppp->active_filter, skb) == 0))
1277                         ppp->last_xmit = jiffies;
1278                 skb_pull(skb, 2);
1279 #else
1280                 /* for data packets, record the time */
1281                 ppp->last_xmit = jiffies;
1282 #endif /* CONFIG_PPP_FILTER */
1283         }
1284 
1285         ++ppp->stats64.tx_packets;
1286         ppp->stats64.tx_bytes += skb->len - 2;
1287 
1288         switch (proto) {
1289         case PPP_IP:
1290                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1291                         break;
1292                 /* try to do VJ TCP header compression */
1293                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1294                                     GFP_ATOMIC);
1295                 if (!new_skb) {
1296                         netdev_err(ppp->dev, "PPP: no memory (VJ comp pkt)\n");
1297                         goto drop;
1298                 }
1299                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1300                 cp = skb->data + 2;
1301                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1302                                     new_skb->data + 2, &cp,
1303                                     !(ppp->flags & SC_NO_TCP_CCID));
1304                 if (cp == skb->data + 2) {
1305                         /* didn't compress */
1306                         consume_skb(new_skb);
1307                 } else {
1308                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1309                                 proto = PPP_VJC_COMP;
1310                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1311                         } else {
1312                                 proto = PPP_VJC_UNCOMP;
1313                                 cp[0] = skb->data[2];
1314                         }
1315                         consume_skb(skb);
1316                         skb = new_skb;
1317                         cp = skb_put(skb, len + 2);
1318                         cp[0] = 0;
1319                         cp[1] = proto;
1320                 }
1321                 break;
1322 
1323         case PPP_CCP:
1324                 /* peek at outbound CCP frames */
1325                 ppp_ccp_peek(ppp, skb, 0);
1326                 break;
1327         }
1328 
1329         /* try to do packet compression */
1330         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state &&
1331             proto != PPP_LCP && proto != PPP_CCP) {
1332                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1333                         if (net_ratelimit())
1334                                 netdev_err(ppp->dev,
1335                                            "ppp: compression required but "
1336                                            "down - pkt dropped.\n");
1337                         goto drop;
1338                 }
1339                 skb = pad_compress_skb(ppp, skb);
1340                 if (!skb)
1341                         goto drop;
1342         }
1343 
1344         /*
1345          * If we are waiting for traffic (demand dialling),
1346          * queue it up for pppd to receive.
1347          */
1348         if (ppp->flags & SC_LOOP_TRAFFIC) {
1349                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1350                         goto drop;
1351                 skb_queue_tail(&ppp->file.rq, skb);
1352                 wake_up_interruptible(&ppp->file.rwait);
1353                 return;
1354         }
1355 
1356         ppp->xmit_pending = skb;
1357         ppp_push(ppp);
1358         return;
1359 
1360  drop:
1361         kfree_skb(skb);
1362         ++ppp->dev->stats.tx_errors;
1363 }
1364 
1365 /*
1366  * Try to send the frame in xmit_pending.
1367  * The caller should have the xmit path locked.
1368  */
1369 static void
1370 ppp_push(struct ppp *ppp)
1371 {
1372         struct list_head *list;
1373         struct channel *pch;
1374         struct sk_buff *skb = ppp->xmit_pending;
1375 
1376         if (!skb)
1377                 return;
1378 
1379         list = &ppp->channels;
1380         if (list_empty(list)) {
1381                 /* nowhere to send the packet, just drop it */
1382                 ppp->xmit_pending = NULL;
1383                 kfree_skb(skb);
1384                 return;
1385         }
1386 
1387         if ((ppp->flags & SC_MULTILINK) == 0) {
1388                 /* not doing multilink: send it down the first channel */
1389                 list = list->next;
1390                 pch = list_entry(list, struct channel, clist);
1391 
1392                 spin_lock_bh(&pch->downl);
1393                 if (pch->chan) {
1394                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1395                                 ppp->xmit_pending = NULL;
1396                 } else {
1397                         /* channel got unregistered */
1398                         kfree_skb(skb);
1399                         ppp->xmit_pending = NULL;
1400                 }
1401                 spin_unlock_bh(&pch->downl);
1402                 return;
1403         }
1404 
1405 #ifdef CONFIG_PPP_MULTILINK
1406         /* Multilink: fragment the packet over as many links
1407            as can take the packet at the moment. */
1408         if (!ppp_mp_explode(ppp, skb))
1409                 return;
1410 #endif /* CONFIG_PPP_MULTILINK */
1411 
1412         ppp->xmit_pending = NULL;
1413         kfree_skb(skb);
1414 }
1415 
1416 #ifdef CONFIG_PPP_MULTILINK
1417 static bool mp_protocol_compress __read_mostly = true;
1418 module_param(mp_protocol_compress, bool, S_IRUGO | S_IWUSR);
1419 MODULE_PARM_DESC(mp_protocol_compress,
1420                  "compress protocol id in multilink fragments");
1421 
1422 /*
1423  * Divide a packet to be transmitted into fragments and
1424  * send them out the individual links.
1425  */
1426 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1427 {
1428         int len, totlen;
1429         int i, bits, hdrlen, mtu;
1430         int flen;
1431         int navail, nfree, nzero;
1432         int nbigger;
1433         int totspeed;
1434         int totfree;
1435         unsigned char *p, *q;
1436         struct list_head *list;
1437         struct channel *pch;
1438         struct sk_buff *frag;
1439         struct ppp_channel *chan;
1440 
1441         totspeed = 0; /*total bitrate of the bundle*/
1442         nfree = 0; /* # channels which have no packet already queued */
1443         navail = 0; /* total # of usable channels (not deregistered) */
1444         nzero = 0; /* number of channels with zero speed associated*/
1445         totfree = 0; /*total # of channels available and
1446                                   *having no queued packets before
1447                                   *starting the fragmentation*/
1448 
1449         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1450         i = 0;
1451         list_for_each_entry(pch, &ppp->channels, clist) {
1452                 if (pch->chan) {
1453                         pch->avail = 1;
1454                         navail++;
1455                         pch->speed = pch->chan->speed;
1456                 } else {
1457                         pch->avail = 0;
1458                 }
1459                 if (pch->avail) {
1460                         if (skb_queue_empty(&pch->file.xq) ||
1461                                 !pch->had_frag) {
1462                                         if (pch->speed == 0)
1463                                                 nzero++;
1464                                         else
1465                                                 totspeed += pch->speed;
1466 
1467                                         pch->avail = 2;
1468                                         ++nfree;
1469                                         ++totfree;
1470                                 }
1471                         if (!pch->had_frag && i < ppp->nxchan)
1472                                 ppp->nxchan = i;
1473                 }
1474                 ++i;
1475         }
1476         /*
1477          * Don't start sending this packet unless at least half of
1478          * the channels are free.  This gives much better TCP
1479          * performance if we have a lot of channels.
1480          */
1481         if (nfree == 0 || nfree < navail / 2)
1482                 return 0; /* can't take now, leave it in xmit_pending */
1483 
1484         /* Do protocol field compression */
1485         p = skb->data;
1486         len = skb->len;
1487         if (*p == 0 && mp_protocol_compress) {
1488                 ++p;
1489                 --len;
1490         }
1491 
1492         totlen = len;
1493         nbigger = len % nfree;
1494 
1495         /* skip to the channel after the one we last used
1496            and start at that one */
1497         list = &ppp->channels;
1498         for (i = 0; i < ppp->nxchan; ++i) {
1499                 list = list->next;
1500                 if (list == &ppp->channels) {
1501                         i = 0;
1502                         break;
1503                 }
1504         }
1505 
1506         /* create a fragment for each channel */
1507         bits = B;
1508         while (len > 0) {
1509                 list = list->next;
1510                 if (list == &ppp->channels) {
1511                         i = 0;
1512                         continue;
1513                 }
1514                 pch = list_entry(list, struct channel, clist);
1515                 ++i;
1516                 if (!pch->avail)
1517                         continue;
1518 
1519                 /*
1520                  * Skip this channel if it has a fragment pending already and
1521                  * we haven't given a fragment to all of the free channels.
1522                  */
1523                 if (pch->avail == 1) {
1524                         if (nfree > 0)
1525                                 continue;
1526                 } else {
1527                         pch->avail = 1;
1528                 }
1529 
1530                 /* check the channel's mtu and whether it is still attached. */
1531                 spin_lock_bh(&pch->downl);
1532                 if (pch->chan == NULL) {
1533                         /* can't use this channel, it's being deregistered */
1534                         if (pch->speed == 0)
1535                                 nzero--;
1536                         else
1537                                 totspeed -= pch->speed;
1538 
1539                         spin_unlock_bh(&pch->downl);
1540                         pch->avail = 0;
1541                         totlen = len;
1542                         totfree--;
1543                         nfree--;
1544                         if (--navail == 0)
1545                                 break;
1546                         continue;
1547                 }
1548 
1549                 /*
1550                 *if the channel speed is not set divide
1551                 *the packet evenly among the free channels;
1552                 *otherwise divide it according to the speed
1553                 *of the channel we are going to transmit on
1554                 */
1555                 flen = len;
1556                 if (nfree > 0) {
1557                         if (pch->speed == 0) {
1558                                 flen = len/nfree;
1559                                 if (nbigger > 0) {
1560                                         flen++;
1561                                         nbigger--;
1562                                 }
1563                         } else {
1564                                 flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
1565                                         ((totspeed*totfree)/pch->speed)) - hdrlen;
1566                                 if (nbigger > 0) {
1567                                         flen += ((totfree - nzero)*pch->speed)/totspeed;
1568                                         nbigger -= ((totfree - nzero)*pch->speed)/
1569                                                         totspeed;
1570                                 }
1571                         }
1572                         nfree--;
1573                 }
1574 
1575                 /*
1576                  *check if we are on the last channel or
1577                  *we exceded the length of the data to
1578                  *fragment
1579                  */
1580                 if ((nfree <= 0) || (flen > len))
1581                         flen = len;
1582                 /*
1583                  *it is not worth to tx on slow channels:
1584                  *in that case from the resulting flen according to the
1585                  *above formula will be equal or less than zero.
1586                  *Skip the channel in this case
1587                  */
1588                 if (flen <= 0) {
1589                         pch->avail = 2;
1590                         spin_unlock_bh(&pch->downl);
1591                         continue;
1592                 }
1593 
1594                 /*
1595                  * hdrlen includes the 2-byte PPP protocol field, but the
1596                  * MTU counts only the payload excluding the protocol field.
1597                  * (RFC1661 Section 2)
1598                  */
1599                 mtu = pch->chan->mtu - (hdrlen - 2);
1600                 if (mtu < 4)
1601                         mtu = 4;
1602                 if (flen > mtu)
1603                         flen = mtu;
1604                 if (flen == len)
1605                         bits |= E;
1606                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1607                 if (!frag)
1608                         goto noskb;
1609                 q = skb_put(frag, flen + hdrlen);
1610 
1611                 /* make the MP header */
1612                 put_unaligned_be16(PPP_MP, q);
1613                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1614                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1615                         q[3] = ppp->nxseq;
1616                 } else {
1617                         q[2] = bits;
1618                         q[3] = ppp->nxseq >> 16;
1619                         q[4] = ppp->nxseq >> 8;
1620                         q[5] = ppp->nxseq;
1621                 }
1622 
1623                 memcpy(q + hdrlen, p, flen);
1624 
1625                 /* try to send it down the channel */
1626                 chan = pch->chan;
1627                 if (!skb_queue_empty(&pch->file.xq) ||
1628                         !chan->ops->start_xmit(chan, frag))
1629                         skb_queue_tail(&pch->file.xq, frag);
1630                 pch->had_frag = 1;
1631                 p += flen;
1632                 len -= flen;
1633                 ++ppp->nxseq;
1634                 bits = 0;
1635                 spin_unlock_bh(&pch->downl);
1636         }
1637         ppp->nxchan = i;
1638 
1639         return 1;
1640 
1641  noskb:
1642         spin_unlock_bh(&pch->downl);
1643         if (ppp->debug & 1)
1644                 netdev_err(ppp->dev, "PPP: no memory (fragment)\n");
1645         ++ppp->dev->stats.tx_errors;
1646         ++ppp->nxseq;
1647         return 1;       /* abandon the frame */
1648 }
1649 #endif /* CONFIG_PPP_MULTILINK */
1650 
1651 /*
1652  * Try to send data out on a channel.
1653  */
1654 static void
1655 ppp_channel_push(struct channel *pch)
1656 {
1657         struct sk_buff *skb;
1658         struct ppp *ppp;
1659 
1660         spin_lock_bh(&pch->downl);
1661         if (pch->chan) {
1662                 while (!skb_queue_empty(&pch->file.xq)) {
1663                         skb = skb_dequeue(&pch->file.xq);
1664                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1665                                 /* put the packet back and try again later */
1666                                 skb_queue_head(&pch->file.xq, skb);
1667                                 break;
1668                         }
1669                 }
1670         } else {
1671                 /* channel got deregistered */
1672                 skb_queue_purge(&pch->file.xq);
1673         }
1674         spin_unlock_bh(&pch->downl);
1675         /* see if there is anything from the attached unit to be sent */
1676         if (skb_queue_empty(&pch->file.xq)) {
1677                 read_lock_bh(&pch->upl);
1678                 ppp = pch->ppp;
1679                 if (ppp)
1680                         ppp_xmit_process(ppp);
1681                 read_unlock_bh(&pch->upl);
1682         }
1683 }
1684 
1685 /*
1686  * Receive-side routines.
1687  */
1688 
1689 struct ppp_mp_skb_parm {
1690         u32             sequence;
1691         u8              BEbits;
1692 };
1693 #define PPP_MP_CB(skb)  ((struct ppp_mp_skb_parm *)((skb)->cb))
1694 
1695 static inline void
1696 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1697 {
1698         ppp_recv_lock(ppp);
1699         if (!ppp->closing)
1700                 ppp_receive_frame(ppp, skb, pch);
1701         else
1702                 kfree_skb(skb);
1703         ppp_recv_unlock(ppp);
1704 }
1705 
1706 void
1707 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1708 {
1709         struct channel *pch = chan->ppp;
1710         int proto;
1711 
1712         if (!pch) {
1713                 kfree_skb(skb);
1714                 return;
1715         }
1716 
1717         read_lock_bh(&pch->upl);
1718         if (!pskb_may_pull(skb, 2)) {
1719                 kfree_skb(skb);
1720                 if (pch->ppp) {
1721                         ++pch->ppp->dev->stats.rx_length_errors;
1722                         ppp_receive_error(pch->ppp);
1723                 }
1724                 goto done;
1725         }
1726 
1727         proto = PPP_PROTO(skb);
1728         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1729                 /* put it on the channel queue */
1730                 skb_queue_tail(&pch->file.rq, skb);
1731                 /* drop old frames if queue too long */
1732                 while (pch->file.rq.qlen > PPP_MAX_RQLEN &&
1733                        (skb = skb_dequeue(&pch->file.rq)))
1734                         kfree_skb(skb);
1735                 wake_up_interruptible(&pch->file.rwait);
1736         } else {
1737                 ppp_do_recv(pch->ppp, skb, pch);
1738         }
1739 
1740 done:
1741         read_unlock_bh(&pch->upl);
1742 }
1743 
1744 /* Put a 0-length skb in the receive queue as an error indication */
1745 void
1746 ppp_input_error(struct ppp_channel *chan, int code)
1747 {
1748         struct channel *pch = chan->ppp;
1749         struct sk_buff *skb;
1750 
1751         if (!pch)
1752                 return;
1753 
1754         read_lock_bh(&pch->upl);
1755         if (pch->ppp) {
1756                 skb = alloc_skb(0, GFP_ATOMIC);
1757                 if (skb) {
1758                         skb->len = 0;           /* probably unnecessary */
1759                         skb->cb[0] = code;
1760                         ppp_do_recv(pch->ppp, skb, pch);
1761                 }
1762         }
1763         read_unlock_bh(&pch->upl);
1764 }
1765 
1766 /*
1767  * We come in here to process a received frame.
1768  * The receive side of the ppp unit is locked.
1769  */
1770 static void
1771 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1772 {
1773         /* note: a 0-length skb is used as an error indication */
1774         if (skb->len > 0) {
1775                 skb_checksum_complete_unset(skb);
1776 #ifdef CONFIG_PPP_MULTILINK
1777                 /* XXX do channel-level decompression here */
1778                 if (PPP_PROTO(skb) == PPP_MP)
1779                         ppp_receive_mp_frame(ppp, skb, pch);
1780                 else
1781 #endif /* CONFIG_PPP_MULTILINK */
1782                         ppp_receive_nonmp_frame(ppp, skb);
1783         } else {
1784                 kfree_skb(skb);
1785                 ppp_receive_error(ppp);
1786         }
1787 }
1788 
1789 static void
1790 ppp_receive_error(struct ppp *ppp)
1791 {
1792         ++ppp->dev->stats.rx_errors;
1793         if (ppp->vj)
1794                 slhc_toss(ppp->vj);
1795 }
1796 
1797 static void
1798 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1799 {
1800         struct sk_buff *ns;
1801         int proto, len, npi;
1802 
1803         /*
1804          * Decompress the frame, if compressed.
1805          * Note that some decompressors need to see uncompressed frames
1806          * that come in as well as compressed frames.
1807          */
1808         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN) &&
1809             (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1810                 skb = ppp_decompress_frame(ppp, skb);
1811 
1812         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1813                 goto err;
1814 
1815         proto = PPP_PROTO(skb);
1816         switch (proto) {
1817         case PPP_VJC_COMP:
1818                 /* decompress VJ compressed packets */
1819                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1820                         goto err;
1821 
1822                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1823                         /* copy to a new sk_buff with more tailroom */
1824                         ns = dev_alloc_skb(skb->len + 128);
1825                         if (!ns) {
1826                                 netdev_err(ppp->dev, "PPP: no memory "
1827                                            "(VJ decomp)\n");
1828                                 goto err;
1829                         }
1830                         skb_reserve(ns, 2);
1831                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1832                         consume_skb(skb);
1833                         skb = ns;
1834                 }
1835                 else
1836                         skb->ip_summed = CHECKSUM_NONE;
1837 
1838                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1839                 if (len <= 0) {
1840                         netdev_printk(KERN_DEBUG, ppp->dev,
1841                                       "PPP: VJ decompression error\n");
1842                         goto err;
1843                 }
1844                 len += 2;
1845                 if (len > skb->len)
1846                         skb_put(skb, len - skb->len);
1847                 else if (len < skb->len)
1848                         skb_trim(skb, len);
1849                 proto = PPP_IP;
1850                 break;
1851 
1852         case PPP_VJC_UNCOMP:
1853                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1854                         goto err;
1855 
1856                 /* Until we fix the decompressor need to make sure
1857                  * data portion is linear.
1858                  */
1859                 if (!pskb_may_pull(skb, skb->len))
1860                         goto err;
1861 
1862                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1863                         netdev_err(ppp->dev, "PPP: VJ uncompressed error\n");
1864                         goto err;
1865                 }
1866                 proto = PPP_IP;
1867                 break;
1868 
1869         case PPP_CCP:
1870                 ppp_ccp_peek(ppp, skb, 1);
1871                 break;
1872         }
1873 
1874         ++ppp->stats64.rx_packets;
1875         ppp->stats64.rx_bytes += skb->len - 2;
1876 
1877         npi = proto_to_npindex(proto);
1878         if (npi < 0) {
1879                 /* control or unknown frame - pass it to pppd */
1880                 skb_queue_tail(&ppp->file.rq, skb);
1881                 /* limit queue length by dropping old frames */
1882                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN &&
1883                        (skb = skb_dequeue(&ppp->file.rq)))
1884                         kfree_skb(skb);
1885                 /* wake up any process polling or blocking on read */
1886                 wake_up_interruptible(&ppp->file.rwait);
1887 
1888         } else {
1889                 /* network protocol frame - give it to the kernel */
1890 
1891 #ifdef CONFIG_PPP_FILTER
1892                 /* check if the packet passes the pass and active filters */
1893                 /* the filter instructions are constructed assuming
1894                    a four-byte PPP header on each packet */
1895                 if (ppp->pass_filter || ppp->active_filter) {
1896                         if (skb_unclone(skb, GFP_ATOMIC))
1897                                 goto err;
1898 
1899                         *skb_push(skb, 2) = 0;
1900                         if (ppp->pass_filter &&
1901                             BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
1902                                 if (ppp->debug & 1)
1903                                         netdev_printk(KERN_DEBUG, ppp->dev,
1904                                                       "PPP: inbound frame "
1905                                                       "not passed\n");
1906                                 kfree_skb(skb);
1907                                 return;
1908                         }
1909                         if (!(ppp->active_filter &&
1910                               BPF_PROG_RUN(ppp->active_filter, skb) == 0))
1911                                 ppp->last_recv = jiffies;
1912                         __skb_pull(skb, 2);
1913                 } else
1914 #endif /* CONFIG_PPP_FILTER */
1915                         ppp->last_recv = jiffies;
1916 
1917                 if ((ppp->dev->flags & IFF_UP) == 0 ||
1918                     ppp->npmode[npi] != NPMODE_PASS) {
1919                         kfree_skb(skb);
1920                 } else {
1921                         /* chop off protocol */
1922                         skb_pull_rcsum(skb, 2);
1923                         skb->dev = ppp->dev;
1924                         skb->protocol = htons(npindex_to_ethertype[npi]);
1925                         skb_reset_mac_header(skb);
1926                         skb_scrub_packet(skb, !net_eq(ppp->ppp_net,
1927                                                       dev_net(ppp->dev)));
1928                         netif_rx(skb);
1929                 }
1930         }
1931         return;
1932 
1933  err:
1934         kfree_skb(skb);
1935         ppp_receive_error(ppp);
1936 }
1937 
1938 static struct sk_buff *
1939 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1940 {
1941         int proto = PPP_PROTO(skb);
1942         struct sk_buff *ns;
1943         int len;
1944 
1945         /* Until we fix all the decompressor's need to make sure
1946          * data portion is linear.
1947          */
1948         if (!pskb_may_pull(skb, skb->len))
1949                 goto err;
1950 
1951         if (proto == PPP_COMP) {
1952                 int obuff_size;
1953 
1954                 switch(ppp->rcomp->compress_proto) {
1955                 case CI_MPPE:
1956                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1957                         break;
1958                 default:
1959                         obuff_size = ppp->mru + PPP_HDRLEN;
1960                         break;
1961                 }
1962 
1963                 ns = dev_alloc_skb(obuff_size);
1964                 if (!ns) {
1965                         netdev_err(ppp->dev, "ppp_decompress_frame: "
1966                                    "no memory\n");
1967                         goto err;
1968                 }
1969                 /* the decompressor still expects the A/C bytes in the hdr */
1970                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1971                                 skb->len + 2, ns->data, obuff_size);
1972                 if (len < 0) {
1973                         /* Pass the compressed frame to pppd as an
1974                            error indication. */
1975                         if (len == DECOMP_FATALERROR)
1976                                 ppp->rstate |= SC_DC_FERROR;
1977                         kfree_skb(ns);
1978                         goto err;
1979                 }
1980 
1981                 consume_skb(skb);
1982                 skb = ns;
1983                 skb_put(skb, len);
1984                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1985 
1986         } else {
1987                 /* Uncompressed frame - pass to decompressor so it
1988                    can update its dictionary if necessary. */
1989                 if (ppp->rcomp->incomp)
1990                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1991                                            skb->len + 2);
1992         }
1993 
1994         return skb;
1995 
1996  err:
1997         ppp->rstate |= SC_DC_ERROR;
1998         ppp_receive_error(ppp);
1999         return skb;
2000 }
2001 
2002 #ifdef CONFIG_PPP_MULTILINK
2003 /*
2004  * Receive a multilink frame.
2005  * We put it on the reconstruction queue and then pull off
2006  * as many completed frames as we can.
2007  */
2008 static void
2009 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
2010 {
2011         u32 mask, seq;
2012         struct channel *ch;
2013         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
2014 
2015         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
2016                 goto err;               /* no good, throw it away */
2017 
2018         /* Decode sequence number and begin/end bits */
2019         if (ppp->flags & SC_MP_SHORTSEQ) {
2020                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
2021                 mask = 0xfff;
2022         } else {
2023                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
2024                 mask = 0xffffff;
2025         }
2026         PPP_MP_CB(skb)->BEbits = skb->data[2];
2027         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
2028 
2029         /*
2030          * Do protocol ID decompression on the first fragment of each packet.
2031          */
2032         if ((PPP_MP_CB(skb)->BEbits & B) && (skb->data[0] & 1))
2033                 *skb_push(skb, 1) = 0;
2034 
2035         /*
2036          * Expand sequence number to 32 bits, making it as close
2037          * as possible to ppp->minseq.
2038          */
2039         seq |= ppp->minseq & ~mask;
2040         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
2041                 seq += mask + 1;
2042         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
2043                 seq -= mask + 1;        /* should never happen */
2044         PPP_MP_CB(skb)->sequence = seq;
2045         pch->lastseq = seq;
2046 
2047         /*
2048          * If this packet comes before the next one we were expecting,
2049          * drop it.
2050          */
2051         if (seq_before(seq, ppp->nextseq)) {
2052                 kfree_skb(skb);
2053                 ++ppp->dev->stats.rx_dropped;
2054                 ppp_receive_error(ppp);
2055                 return;
2056         }
2057 
2058         /*
2059          * Reevaluate minseq, the minimum over all channels of the
2060          * last sequence number received on each channel.  Because of
2061          * the increasing sequence number rule, we know that any fragment
2062          * before `minseq' which hasn't arrived is never going to arrive.
2063          * The list of channels can't change because we have the receive
2064          * side of the ppp unit locked.
2065          */
2066         list_for_each_entry(ch, &ppp->channels, clist) {
2067                 if (seq_before(ch->lastseq, seq))
2068                         seq = ch->lastseq;
2069         }
2070         if (seq_before(ppp->minseq, seq))
2071                 ppp->minseq = seq;
2072 
2073         /* Put the fragment on the reconstruction queue */
2074         ppp_mp_insert(ppp, skb);
2075 
2076         /* If the queue is getting long, don't wait any longer for packets
2077            before the start of the queue. */
2078         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
2079                 struct sk_buff *mskb = skb_peek(&ppp->mrq);
2080                 if (seq_before(ppp->minseq, PPP_MP_CB(mskb)->sequence))
2081                         ppp->minseq = PPP_MP_CB(mskb)->sequence;
2082         }
2083 
2084         /* Pull completed packets off the queue and receive them. */
2085         while ((skb = ppp_mp_reconstruct(ppp))) {
2086                 if (pskb_may_pull(skb, 2))
2087                         ppp_receive_nonmp_frame(ppp, skb);
2088                 else {
2089                         ++ppp->dev->stats.rx_length_errors;
2090                         kfree_skb(skb);
2091                         ppp_receive_error(ppp);
2092                 }
2093         }
2094 
2095         return;
2096 
2097  err:
2098         kfree_skb(skb);
2099         ppp_receive_error(ppp);
2100 }
2101 
2102 /*
2103  * Insert a fragment on the MP reconstruction queue.
2104  * The queue is ordered by increasing sequence number.
2105  */
2106 static void
2107 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
2108 {
2109         struct sk_buff *p;
2110         struct sk_buff_head *list = &ppp->mrq;
2111         u32 seq = PPP_MP_CB(skb)->sequence;
2112 
2113         /* N.B. we don't need to lock the list lock because we have the
2114            ppp unit receive-side lock. */
2115         skb_queue_walk(list, p) {
2116                 if (seq_before(seq, PPP_MP_CB(p)->sequence))
2117                         break;
2118         }
2119         __skb_queue_before(list, p, skb);
2120 }
2121 
2122 /*
2123  * Reconstruct a packet from the MP fragment queue.
2124  * We go through increasing sequence numbers until we find a
2125  * complete packet, or we get to the sequence number for a fragment
2126  * which hasn't arrived but might still do so.
2127  */
2128 static struct sk_buff *
2129 ppp_mp_reconstruct(struct ppp *ppp)
2130 {
2131         u32 seq = ppp->nextseq;
2132         u32 minseq = ppp->minseq;
2133         struct sk_buff_head *list = &ppp->mrq;
2134         struct sk_buff *p, *tmp;
2135         struct sk_buff *head, *tail;
2136         struct sk_buff *skb = NULL;
2137         int lost = 0, len = 0;
2138 
2139         if (ppp->mrru == 0)     /* do nothing until mrru is set */
2140                 return NULL;
2141         head = list->next;
2142         tail = NULL;
2143         skb_queue_walk_safe(list, p, tmp) {
2144         again:
2145                 if (seq_before(PPP_MP_CB(p)->sequence, seq)) {
2146                         /* this can't happen, anyway ignore the skb */
2147                         netdev_err(ppp->dev, "ppp_mp_reconstruct bad "
2148                                    "seq %u < %u\n",
2149                                    PPP_MP_CB(p)->sequence, seq);
2150                         __skb_unlink(p, list);
2151                         kfree_skb(p);
2152                         continue;
2153                 }
2154                 if (PPP_MP_CB(p)->sequence != seq) {
2155                         u32 oldseq;
2156                         /* Fragment `seq' is missing.  If it is after
2157                            minseq, it might arrive later, so stop here. */
2158                         if (seq_after(seq, minseq))
2159                                 break;
2160                         /* Fragment `seq' is lost, keep going. */
2161                         lost = 1;
2162                         oldseq = seq;
2163                         seq = seq_before(minseq, PPP_MP_CB(p)->sequence)?
2164                                 minseq + 1: PPP_MP_CB(p)->sequence;
2165 
2166                         if (ppp->debug & 1)
2167                                 netdev_printk(KERN_DEBUG, ppp->dev,
2168                                               "lost frag %u..%u\n",
2169                                               oldseq, seq-1);
2170 
2171                         goto again;
2172                 }
2173 
2174                 /*
2175                  * At this point we know that all the fragments from
2176                  * ppp->nextseq to seq are either present or lost.
2177                  * Also, there are no complete packets in the queue
2178                  * that have no missing fragments and end before this
2179                  * fragment.
2180                  */
2181 
2182                 /* B bit set indicates this fragment starts a packet */
2183                 if (PPP_MP_CB(p)->BEbits & B) {
2184                         head = p;
2185                         lost = 0;
2186                         len = 0;
2187                 }
2188 
2189                 len += p->len;
2190 
2191                 /* Got a complete packet yet? */
2192                 if (lost == 0 && (PPP_MP_CB(p)->BEbits & E) &&
2193                     (PPP_MP_CB(head)->BEbits & B)) {
2194                         if (len > ppp->mrru + 2) {
2195                                 ++ppp->dev->stats.rx_length_errors;
2196                                 netdev_printk(KERN_DEBUG, ppp->dev,
2197                                               "PPP: reconstructed packet"
2198                                               " is too long (%d)\n", len);
2199                         } else {
2200                                 tail = p;
2201                                 break;
2202                         }
2203                         ppp->nextseq = seq + 1;
2204                 }
2205 
2206                 /*
2207                  * If this is the ending fragment of a packet,
2208                  * and we haven't found a complete valid packet yet,
2209                  * we can discard up to and including this fragment.
2210                  */
2211                 if (PPP_MP_CB(p)->BEbits & E) {
2212                         struct sk_buff *tmp2;
2213 
2214                         skb_queue_reverse_walk_from_safe(list, p, tmp2) {
2215                                 if (ppp->debug & 1)
2216                                         netdev_printk(KERN_DEBUG, ppp->dev,
2217                                                       "discarding frag %u\n",
2218                                                       PPP_MP_CB(p)->sequence);
2219                                 __skb_unlink(p, list);
2220                                 kfree_skb(p);
2221                         }
2222                         head = skb_peek(list);
2223                         if (!head)
2224                                 break;
2225                 }
2226                 ++seq;
2227         }
2228 
2229         /* If we have a complete packet, copy it all into one skb. */
2230         if (tail != NULL) {
2231                 /* If we have discarded any fragments,
2232                    signal a receive error. */
2233                 if (PPP_MP_CB(head)->sequence != ppp->nextseq) {
2234                         skb_queue_walk_safe(list, p, tmp) {
2235                                 if (p == head)
2236                                         break;
2237                                 if (ppp->debug & 1)
2238                                         netdev_printk(KERN_DEBUG, ppp->dev,
2239                                                       "discarding frag %u\n",
2240                                                       PPP_MP_CB(p)->sequence);
2241                                 __skb_unlink(p, list);
2242                                 kfree_skb(p);
2243                         }
2244 
2245                         if (ppp->debug & 1)
2246                                 netdev_printk(KERN_DEBUG, ppp->dev,
2247                                               "  missed pkts %u..%u\n",
2248                                               ppp->nextseq,
2249                                               PPP_MP_CB(head)->sequence-1);
2250                         ++ppp->dev->stats.rx_dropped;
2251                         ppp_receive_error(ppp);
2252                 }
2253 
2254                 skb = head;
2255                 if (head != tail) {
2256                         struct sk_buff **fragpp = &skb_shinfo(skb)->frag_list;
2257                         p = skb_queue_next(list, head);
2258                         __skb_unlink(skb, list);
2259                         skb_queue_walk_from_safe(list, p, tmp) {
2260                                 __skb_unlink(p, list);
2261                                 *fragpp = p;
2262                                 p->next = NULL;
2263                                 fragpp = &p->next;
2264 
2265                                 skb->len += p->len;
2266                                 skb->data_len += p->len;
2267                                 skb->truesize += p->truesize;
2268 
2269                                 if (p == tail)
2270                                         break;
2271                         }
2272                 } else {
2273                         __skb_unlink(skb, list);
2274                 }
2275 
2276                 ppp->nextseq = PPP_MP_CB(tail)->sequence + 1;
2277         }
2278 
2279         return skb;
2280 }
2281 #endif /* CONFIG_PPP_MULTILINK */
2282 
2283 /*
2284  * Channel interface.
2285  */
2286 
2287 /* Create a new, unattached ppp channel. */
2288 int ppp_register_channel(struct ppp_channel *chan)
2289 {
2290         return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2291 }
2292 
2293 /* Create a new, unattached ppp channel for specified net. */
2294 int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2295 {
2296         struct channel *pch;
2297         struct ppp_net *pn;
2298 
2299         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2300         if (!pch)
2301                 return -ENOMEM;
2302 
2303         pn = ppp_pernet(net);
2304 
2305         pch->ppp = NULL;
2306         pch->chan = chan;
2307         pch->chan_net = net;
2308         chan->ppp = pch;
2309         init_ppp_file(&pch->file, CHANNEL);
2310         pch->file.hdrlen = chan->hdrlen;
2311 #ifdef CONFIG_PPP_MULTILINK
2312         pch->lastseq = -1;
2313 #endif /* CONFIG_PPP_MULTILINK */
2314         init_rwsem(&pch->chan_sem);
2315         spin_lock_init(&pch->downl);
2316         rwlock_init(&pch->upl);
2317 
2318         spin_lock_bh(&pn->all_channels_lock);
2319         pch->file.index = ++pn->last_channel_index;
2320         list_add(&pch->list, &pn->new_channels);
2321         atomic_inc(&channel_count);
2322         spin_unlock_bh(&pn->all_channels_lock);
2323 
2324         return 0;
2325 }
2326 
2327 /*
2328  * Return the index of a channel.
2329  */
2330 int ppp_channel_index(struct ppp_channel *chan)
2331 {
2332         struct channel *pch = chan->ppp;
2333 
2334         if (pch)
2335                 return pch->file.index;
2336         return -1;
2337 }
2338 
2339 /*
2340  * Return the PPP unit number to which a channel is connected.
2341  */
2342 int ppp_unit_number(struct ppp_channel *chan)
2343 {
2344         struct channel *pch = chan->ppp;
2345         int unit = -1;
2346 
2347         if (pch) {
2348                 read_lock_bh(&pch->upl);
2349                 if (pch->ppp)
2350                         unit = pch->ppp->file.index;
2351                 read_unlock_bh(&pch->upl);
2352         }
2353         return unit;
2354 }
2355 
2356 /*
2357  * Return the PPP device interface name of a channel.
2358  */
2359 char *ppp_dev_name(struct ppp_channel *chan)
2360 {
2361         struct channel *pch = chan->ppp;
2362         char *name = NULL;
2363 
2364         if (pch) {
2365                 read_lock_bh(&pch->upl);
2366                 if (pch->ppp && pch->ppp->dev)
2367                         name = pch->ppp->dev->name;
2368                 read_unlock_bh(&pch->upl);
2369         }
2370         return name;
2371 }
2372 
2373 
2374 /*
2375  * Disconnect a channel from the generic layer.
2376  * This must be called in process context.
2377  */
2378 void
2379 ppp_unregister_channel(struct ppp_channel *chan)
2380 {
2381         struct channel *pch = chan->ppp;
2382         struct ppp_net *pn;
2383 
2384         if (!pch)
2385                 return;         /* should never happen */
2386 
2387         chan->ppp = NULL;
2388 
2389         /*
2390          * This ensures that we have returned from any calls into the
2391          * the channel's start_xmit or ioctl routine before we proceed.
2392          */
2393         down_write(&pch->chan_sem);
2394         spin_lock_bh(&pch->downl);
2395         pch->chan = NULL;
2396         spin_unlock_bh(&pch->downl);
2397         up_write(&pch->chan_sem);
2398         ppp_disconnect_channel(pch);
2399 
2400         pn = ppp_pernet(pch->chan_net);
2401         spin_lock_bh(&pn->all_channels_lock);
2402         list_del(&pch->list);
2403         spin_unlock_bh(&pn->all_channels_lock);
2404 
2405         pch->file.dead = 1;
2406         wake_up_interruptible(&pch->file.rwait);
2407         if (atomic_dec_and_test(&pch->file.refcnt))
2408                 ppp_destroy_channel(pch);
2409 }
2410 
2411 /*
2412  * Callback from a channel when it can accept more to transmit.
2413  * This should be called at BH/softirq level, not interrupt level.
2414  */
2415 void
2416 ppp_output_wakeup(struct ppp_channel *chan)
2417 {
2418         struct channel *pch = chan->ppp;
2419 
2420         if (!pch)
2421                 return;
2422         ppp_channel_push(pch);
2423 }
2424 
2425 /*
2426  * Compression control.
2427  */
2428 
2429 /* Process the PPPIOCSCOMPRESS ioctl. */
2430 static int
2431 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2432 {
2433         int err;
2434         struct compressor *cp, *ocomp;
2435         struct ppp_option_data data;
2436         void *state, *ostate;
2437         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2438 
2439         err = -EFAULT;
2440         if (copy_from_user(&data, (void __user *) arg, sizeof(data)) ||
2441             (data.length <= CCP_MAX_OPTION_LENGTH &&
2442              copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2443                 goto out;
2444         err = -EINVAL;
2445         if (data.length > CCP_MAX_OPTION_LENGTH ||
2446             ccp_option[1] < 2 || ccp_option[1] > data.length)
2447                 goto out;
2448 
2449         cp = try_then_request_module(
2450                 find_compressor(ccp_option[0]),
2451                 "ppp-compress-%d", ccp_option[0]);
2452         if (!cp)
2453                 goto out;
2454 
2455         err = -ENOBUFS;
2456         if (data.transmit) {
2457                 state = cp->comp_alloc(ccp_option, data.length);
2458                 if (state) {
2459                         ppp_xmit_lock(ppp);
2460                         ppp->xstate &= ~SC_COMP_RUN;
2461                         ocomp = ppp->xcomp;
2462                         ostate = ppp->xc_state;
2463                         ppp->xcomp = cp;
2464                         ppp->xc_state = state;
2465                         ppp_xmit_unlock(ppp);
2466                         if (ostate) {
2467                                 ocomp->comp_free(ostate);
2468                                 module_put(ocomp->owner);
2469                         }
2470                         err = 0;
2471                 } else
2472                         module_put(cp->owner);
2473 
2474         } else {
2475                 state = cp->decomp_alloc(ccp_option, data.length);
2476                 if (state) {
2477                         ppp_recv_lock(ppp);
2478                         ppp->rstate &= ~SC_DECOMP_RUN;
2479                         ocomp = ppp->rcomp;
2480                         ostate = ppp->rc_state;
2481                         ppp->rcomp = cp;
2482                         ppp->rc_state = state;
2483                         ppp_recv_unlock(ppp);
2484                         if (ostate) {
2485                                 ocomp->decomp_free(ostate);
2486                                 module_put(ocomp->owner);
2487                         }
2488                         err = 0;
2489                 } else
2490                         module_put(cp->owner);
2491         }
2492 
2493  out:
2494         return err;
2495 }
2496 
2497 /*
2498  * Look at a CCP packet and update our state accordingly.
2499  * We assume the caller has the xmit or recv path locked.
2500  */
2501 static void
2502 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2503 {
2504         unsigned char *dp;
2505         int len;
2506 
2507         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2508                 return; /* no header */
2509         dp = skb->data + 2;
2510 
2511         switch (CCP_CODE(dp)) {
2512         case CCP_CONFREQ:
2513 
2514                 /* A ConfReq starts negotiation of compression
2515                  * in one direction of transmission,
2516                  * and hence brings it down...but which way?
2517                  *
2518                  * Remember:
2519                  * A ConfReq indicates what the sender would like to receive
2520                  */
2521                 if(inbound)
2522                         /* He is proposing what I should send */
2523                         ppp->xstate &= ~SC_COMP_RUN;
2524                 else
2525                         /* I am proposing to what he should send */
2526                         ppp->rstate &= ~SC_DECOMP_RUN;
2527 
2528                 break;
2529 
2530         case CCP_TERMREQ:
2531         case CCP_TERMACK:
2532                 /*
2533                  * CCP is going down, both directions of transmission
2534                  */
2535                 ppp->rstate &= ~SC_DECOMP_RUN;
2536                 ppp->xstate &= ~SC_COMP_RUN;
2537                 break;
2538 
2539         case CCP_CONFACK:
2540                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2541                         break;
2542                 len = CCP_LENGTH(dp);
2543                 if (!pskb_may_pull(skb, len + 2))
2544                         return;         /* too short */
2545                 dp += CCP_HDRLEN;
2546                 len -= CCP_HDRLEN;
2547                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2548                         break;
2549                 if (inbound) {
2550                         /* we will start receiving compressed packets */
2551                         if (!ppp->rc_state)
2552                                 break;
2553                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2554                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2555                                 ppp->rstate |= SC_DECOMP_RUN;
2556                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2557                         }
2558                 } else {
2559                         /* we will soon start sending compressed packets */
2560                         if (!ppp->xc_state)
2561                                 break;
2562                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2563                                         ppp->file.index, 0, ppp->debug))
2564                                 ppp->xstate |= SC_COMP_RUN;
2565                 }
2566                 break;
2567 
2568         case CCP_RESETACK:
2569                 /* reset the [de]compressor */
2570                 if ((ppp->flags & SC_CCP_UP) == 0)
2571                         break;
2572                 if (inbound) {
2573                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2574                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2575                                 ppp->rstate &= ~SC_DC_ERROR;
2576                         }
2577                 } else {
2578                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2579                                 ppp->xcomp->comp_reset(ppp->xc_state);
2580                 }
2581                 break;
2582         }
2583 }
2584 
2585 /* Free up compression resources. */
2586 static void
2587 ppp_ccp_closed(struct ppp *ppp)
2588 {
2589         void *xstate, *rstate;
2590         struct compressor *xcomp, *rcomp;
2591 
2592         ppp_lock(ppp);
2593         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2594         ppp->xstate = 0;
2595         xcomp = ppp->xcomp;
2596         xstate = ppp->xc_state;
2597         ppp->xc_state = NULL;
2598         ppp->rstate = 0;
2599         rcomp = ppp->rcomp;
2600         rstate = ppp->rc_state;
2601         ppp->rc_state = NULL;
2602         ppp_unlock(ppp);
2603 
2604         if (xstate) {
2605                 xcomp->comp_free(xstate);
2606                 module_put(xcomp->owner);
2607         }
2608         if (rstate) {
2609                 rcomp->decomp_free(rstate);
2610                 module_put(rcomp->owner);
2611         }
2612 }
2613 
2614 /* List of compressors. */
2615 static LIST_HEAD(compressor_list);
2616 static DEFINE_SPINLOCK(compressor_list_lock);
2617 
2618 struct compressor_entry {
2619         struct list_head list;
2620         struct compressor *comp;
2621 };
2622 
2623 static struct compressor_entry *
2624 find_comp_entry(int proto)
2625 {
2626         struct compressor_entry *ce;
2627 
2628         list_for_each_entry(ce, &compressor_list, list) {
2629                 if (ce->comp->compress_proto == proto)
2630                         return ce;
2631         }
2632         return NULL;
2633 }
2634 
2635 /* Register a compressor */
2636 int
2637 ppp_register_compressor(struct compressor *cp)
2638 {
2639         struct compressor_entry *ce;
2640         int ret;
2641         spin_lock(&compressor_list_lock);
2642         ret = -EEXIST;
2643         if (find_comp_entry(cp->compress_proto))
2644                 goto out;
2645         ret = -ENOMEM;
2646         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2647         if (!ce)
2648                 goto out;
2649         ret = 0;
2650         ce->comp = cp;
2651         list_add(&ce->list, &compressor_list);
2652  out:
2653         spin_unlock(&compressor_list_lock);
2654         return ret;
2655 }
2656 
2657 /* Unregister a compressor */
2658 void
2659 ppp_unregister_compressor(struct compressor *cp)
2660 {
2661         struct compressor_entry *ce;
2662 
2663         spin_lock(&compressor_list_lock);
2664         ce = find_comp_entry(cp->compress_proto);
2665         if (ce && ce->comp == cp) {
2666                 list_del(&ce->list);
2667                 kfree(ce);
2668         }
2669         spin_unlock(&compressor_list_lock);
2670 }
2671 
2672 /* Find a compressor. */
2673 static struct compressor *
2674 find_compressor(int type)
2675 {
2676         struct compressor_entry *ce;
2677         struct compressor *cp = NULL;
2678 
2679         spin_lock(&compressor_list_lock);
2680         ce = find_comp_entry(type);
2681         if (ce) {
2682                 cp = ce->comp;
2683                 if (!try_module_get(cp->owner))
2684                         cp = NULL;
2685         }
2686         spin_unlock(&compressor_list_lock);
2687         return cp;
2688 }
2689 
2690 /*
2691  * Miscelleneous stuff.
2692  */
2693 
2694 static void
2695 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2696 {
2697         struct slcompress *vj = ppp->vj;
2698 
2699         memset(st, 0, sizeof(*st));
2700         st->p.ppp_ipackets = ppp->stats64.rx_packets;
2701         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2702         st->p.ppp_ibytes = ppp->stats64.rx_bytes;
2703         st->p.ppp_opackets = ppp->stats64.tx_packets;
2704         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2705         st->p.ppp_obytes = ppp->stats64.tx_bytes;
2706         if (!vj)
2707                 return;
2708         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2709         st->vj.vjs_compressed = vj->sls_o_compressed;
2710         st->vj.vjs_searches = vj->sls_o_searches;
2711         st->vj.vjs_misses = vj->sls_o_misses;
2712         st->vj.vjs_errorin = vj->sls_i_error;
2713         st->vj.vjs_tossed = vj->sls_i_tossed;
2714         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2715         st->vj.vjs_compressedin = vj->sls_i_compressed;
2716 }
2717 
2718 /*
2719  * Stuff for handling the lists of ppp units and channels
2720  * and for initialization.
2721  */
2722 
2723 /*
2724  * Create a new ppp interface unit.  Fails if it can't allocate memory
2725  * or if there is already a unit with the requested number.
2726  * unit == -1 means allocate a new number.
2727  */
2728 static struct ppp *ppp_create_interface(struct net *net, int unit,
2729                                         struct file *file, int *retp)
2730 {
2731         struct ppp *ppp;
2732         struct ppp_net *pn;
2733         struct net_device *dev = NULL;
2734         int ret = -ENOMEM;
2735         int i;
2736 
2737         dev = alloc_netdev(sizeof(struct ppp), "", NET_NAME_ENUM, ppp_setup);
2738         if (!dev)
2739                 goto out1;
2740 
2741         pn = ppp_pernet(net);
2742 
2743         ppp = netdev_priv(dev);
2744         ppp->dev = dev;
2745         ppp->mru = PPP_MRU;
2746         init_ppp_file(&ppp->file, INTERFACE);
2747         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2748         ppp->owner = file;
2749         for (i = 0; i < NUM_NP; ++i)
2750                 ppp->npmode[i] = NPMODE_PASS;
2751         INIT_LIST_HEAD(&ppp->channels);
2752         spin_lock_init(&ppp->rlock);
2753         spin_lock_init(&ppp->wlock);
2754 #ifdef CONFIG_PPP_MULTILINK
2755         ppp->minseq = -1;
2756         skb_queue_head_init(&ppp->mrq);
2757 #endif /* CONFIG_PPP_MULTILINK */
2758 #ifdef CONFIG_PPP_FILTER
2759         ppp->pass_filter = NULL;
2760         ppp->active_filter = NULL;
2761 #endif /* CONFIG_PPP_FILTER */
2762 
2763         /*
2764          * drum roll: don't forget to set
2765          * the net device is belong to
2766          */
2767         dev_net_set(dev, net);
2768 
2769         rtnl_lock();
2770         mutex_lock(&pn->all_ppp_mutex);
2771 
2772         if (unit < 0) {
2773                 unit = unit_get(&pn->units_idr, ppp);
2774                 if (unit < 0) {
2775                         ret = unit;
2776                         goto out2;
2777                 }
2778         } else {
2779                 ret = -EEXIST;
2780                 if (unit_find(&pn->units_idr, unit))
2781                         goto out2; /* unit already exists */
2782                 /*
2783                  * if caller need a specified unit number
2784                  * lets try to satisfy him, otherwise --
2785                  * he should better ask us for new unit number
2786                  *
2787                  * NOTE: yes I know that returning EEXIST it's not
2788                  * fair but at least pppd will ask us to allocate
2789                  * new unit in this case so user is happy :)
2790                  */
2791                 unit = unit_set(&pn->units_idr, ppp, unit);
2792                 if (unit < 0)
2793                         goto out2;
2794         }
2795 
2796         /* Initialize the new ppp unit */
2797         ppp->file.index = unit;
2798         sprintf(dev->name, "ppp%d", unit);
2799 
2800         ret = register_netdevice(dev);
2801         if (ret != 0) {
2802                 unit_put(&pn->units_idr, unit);
2803                 netdev_err(ppp->dev, "PPP: couldn't register device %s (%d)\n",
2804                            dev->name, ret);
2805                 goto out2;
2806         }
2807 
2808         ppp->ppp_net = net;
2809 
2810         atomic_inc(&ppp_unit_count);
2811         mutex_unlock(&pn->all_ppp_mutex);
2812         rtnl_unlock();
2813 
2814         *retp = 0;
2815         return ppp;
2816 
2817 out2:
2818         mutex_unlock(&pn->all_ppp_mutex);
2819         rtnl_unlock();
2820         free_netdev(dev);
2821 out1:
2822         *retp = ret;
2823         return NULL;
2824 }
2825 
2826 /*
2827  * Initialize a ppp_file structure.
2828  */
2829 static void
2830 init_ppp_file(struct ppp_file *pf, int kind)
2831 {
2832         pf->kind = kind;
2833         skb_queue_head_init(&pf->xq);
2834         skb_queue_head_init(&pf->rq);
2835         atomic_set(&pf->refcnt, 1);
2836         init_waitqueue_head(&pf->rwait);
2837 }
2838 
2839 /*
2840  * Free the memory used by a ppp unit.  This is only called once
2841  * there are no channels connected to the unit and no file structs
2842  * that reference the unit.
2843  */
2844 static void ppp_destroy_interface(struct ppp *ppp)
2845 {
2846         atomic_dec(&ppp_unit_count);
2847 
2848         if (!ppp->file.dead || ppp->n_channels) {
2849                 /* "can't happen" */
2850                 netdev_err(ppp->dev, "ppp: destroying ppp struct %p "
2851                            "but dead=%d n_channels=%d !\n",
2852                            ppp, ppp->file.dead, ppp->n_channels);
2853                 return;
2854         }
2855 
2856         ppp_ccp_closed(ppp);
2857         if (ppp->vj) {
2858                 slhc_free(ppp->vj);
2859                 ppp->vj = NULL;
2860         }
2861         skb_queue_purge(&ppp->file.xq);
2862         skb_queue_purge(&ppp->file.rq);
2863 #ifdef CONFIG_PPP_MULTILINK
2864         skb_queue_purge(&ppp->mrq);
2865 #endif /* CONFIG_PPP_MULTILINK */
2866 #ifdef CONFIG_PPP_FILTER
2867         if (ppp->pass_filter) {
2868                 bpf_prog_destroy(ppp->pass_filter);
2869                 ppp->pass_filter = NULL;
2870         }
2871 
2872         if (ppp->active_filter) {
2873                 bpf_prog_destroy(ppp->active_filter);
2874                 ppp->active_filter = NULL;
2875         }
2876 #endif /* CONFIG_PPP_FILTER */
2877 
2878         kfree_skb(ppp->xmit_pending);
2879 
2880         free_netdev(ppp->dev);
2881 }
2882 
2883 /*
2884  * Locate an existing ppp unit.
2885  * The caller should have locked the all_ppp_mutex.
2886  */
2887 static struct ppp *
2888 ppp_find_unit(struct ppp_net *pn, int unit)
2889 {
2890         return unit_find(&pn->units_idr, unit);
2891 }
2892 
2893 /*
2894  * Locate an existing ppp channel.
2895  * The caller should have locked the all_channels_lock.
2896  * First we look in the new_channels list, then in the
2897  * all_channels list.  If found in the new_channels list,
2898  * we move it to the all_channels list.  This is for speed
2899  * when we have a lot of channels in use.
2900  */
2901 static struct channel *
2902 ppp_find_channel(struct ppp_net *pn, int unit)
2903 {
2904         struct channel *pch;
2905 
2906         list_for_each_entry(pch, &pn->new_channels, list) {
2907                 if (pch->file.index == unit) {
2908                         list_move(&pch->list, &pn->all_channels);
2909                         return pch;
2910                 }
2911         }
2912 
2913         list_for_each_entry(pch, &pn->all_channels, list) {
2914                 if (pch->file.index == unit)
2915                         return pch;
2916         }
2917 
2918         return NULL;
2919 }
2920 
2921 /*
2922  * Connect a PPP channel to a PPP interface unit.
2923  */
2924 static int
2925 ppp_connect_channel(struct channel *pch, int unit)
2926 {
2927         struct ppp *ppp;
2928         struct ppp_net *pn;
2929         int ret = -ENXIO;
2930         int hdrlen;
2931 
2932         pn = ppp_pernet(pch->chan_net);
2933 
2934         mutex_lock(&pn->all_ppp_mutex);
2935         ppp = ppp_find_unit(pn, unit);
2936         if (!ppp)
2937                 goto out;
2938         write_lock_bh(&pch->upl);
2939         ret = -EINVAL;
2940         if (pch->ppp)
2941                 goto outl;
2942 
2943         ppp_lock(ppp);
2944         if (pch->file.hdrlen > ppp->file.hdrlen)
2945                 ppp->file.hdrlen = pch->file.hdrlen;
2946         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2947         if (hdrlen > ppp->dev->hard_header_len)
2948                 ppp->dev->hard_header_len = hdrlen;
2949         list_add_tail(&pch->clist, &ppp->channels);
2950         ++ppp->n_channels;
2951         pch->ppp = ppp;
2952         atomic_inc(&ppp->file.refcnt);
2953         ppp_unlock(ppp);
2954         ret = 0;
2955 
2956  outl:
2957         write_unlock_bh(&pch->upl);
2958  out:
2959         mutex_unlock(&pn->all_ppp_mutex);
2960         return ret;
2961 }
2962 
2963 /*
2964  * Disconnect a channel from its ppp unit.
2965  */
2966 static int
2967 ppp_disconnect_channel(struct channel *pch)
2968 {
2969         struct ppp *ppp;
2970         int err = -EINVAL;
2971 
2972         write_lock_bh(&pch->upl);
2973         ppp = pch->ppp;
2974         pch->ppp = NULL;
2975         write_unlock_bh(&pch->upl);
2976         if (ppp) {
2977                 /* remove it from the ppp unit's list */
2978                 ppp_lock(ppp);
2979                 list_del(&pch->clist);
2980                 if (--ppp->n_channels == 0)
2981                         wake_up_interruptible(&ppp->file.rwait);
2982                 ppp_unlock(ppp);
2983                 if (atomic_dec_and_test(&ppp->file.refcnt))
2984                         ppp_destroy_interface(ppp);
2985                 err = 0;
2986         }
2987         return err;
2988 }
2989 
2990 /*
2991  * Free up the resources used by a ppp channel.
2992  */
2993 static void ppp_destroy_channel(struct channel *pch)
2994 {
2995         atomic_dec(&channel_count);
2996 
2997         if (!pch->file.dead) {
2998                 /* "can't happen" */
2999                 pr_err("ppp: destroying undead channel %p !\n", pch);
3000                 return;
3001         }
3002         skb_queue_purge(&pch->file.xq);
3003         skb_queue_purge(&pch->file.rq);
3004         kfree(pch);
3005 }
3006 
3007 static void __exit ppp_cleanup(void)
3008 {
3009         /* should never happen */
3010         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
3011                 pr_err("PPP: removing module but units remain!\n");
3012         unregister_chrdev(PPP_MAJOR, "ppp");
3013         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
3014         class_destroy(ppp_class);
3015         unregister_pernet_device(&ppp_net_ops);
3016 }
3017 
3018 /*
3019  * Units handling. Caller must protect concurrent access
3020  * by holding all_ppp_mutex
3021  */
3022 
3023 /* associate pointer with specified number */
3024 static int unit_set(struct idr *p, void *ptr, int n)
3025 {
3026         int unit;
3027 
3028         unit = idr_alloc(p, ptr, n, n + 1, GFP_KERNEL);
3029         if (unit == -ENOSPC)
3030                 unit = -EINVAL;
3031         return unit;
3032 }
3033 
3034 /* get new free unit number and associate pointer with it */
3035 static int unit_get(struct idr *p, void *ptr)
3036 {
3037         return idr_alloc(p, ptr, 0, 0, GFP_KERNEL);
3038 }
3039 
3040 /* put unit number back to a pool */
3041 static void unit_put(struct idr *p, int n)
3042 {
3043         idr_remove(p, n);
3044 }
3045 
3046 /* get pointer associated with the number */
3047 static void *unit_find(struct idr *p, int n)
3048 {
3049         return idr_find(p, n);
3050 }
3051 
3052 /* Module/initialization stuff */
3053 
3054 module_init(ppp_init);
3055 module_exit(ppp_cleanup);
3056 
3057 EXPORT_SYMBOL(ppp_register_net_channel);
3058 EXPORT_SYMBOL(ppp_register_channel);
3059 EXPORT_SYMBOL(ppp_unregister_channel);
3060 EXPORT_SYMBOL(ppp_channel_index);
3061 EXPORT_SYMBOL(ppp_unit_number);
3062 EXPORT_SYMBOL(ppp_dev_name);
3063 EXPORT_SYMBOL(ppp_input);
3064 EXPORT_SYMBOL(ppp_input_error);
3065 EXPORT_SYMBOL(ppp_output_wakeup);
3066 EXPORT_SYMBOL(ppp_register_compressor);
3067 EXPORT_SYMBOL(ppp_unregister_compressor);
3068 MODULE_LICENSE("GPL");
3069 MODULE_ALIAS_CHARDEV(PPP_MAJOR, 0);
3070 MODULE_ALIAS("devname:ppp");
3071 

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