Version:  2.0.40 2.2.26 2.4.37 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0

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, int *retp);
273 static void init_ppp_file(struct ppp_file *pf, int kind);
274 static void ppp_shutdown_interface(struct ppp *ppp);
275 static void ppp_destroy_interface(struct ppp *ppp);
276 static struct ppp *ppp_find_unit(struct ppp_net *pn, int unit);
277 static struct channel *ppp_find_channel(struct ppp_net *pn, int unit);
278 static int ppp_connect_channel(struct channel *pch, int unit);
279 static int ppp_disconnect_channel(struct channel *pch);
280 static void ppp_destroy_channel(struct channel *pch);
281 static int unit_get(struct idr *p, void *ptr);
282 static int unit_set(struct idr *p, void *ptr, int n);
283 static void unit_put(struct idr *p, int n);
284 static void *unit_find(struct idr *p, int n);
285 
286 static struct class *ppp_class;
287 
288 /* per net-namespace data */
289 static inline struct ppp_net *ppp_pernet(struct net *net)
290 {
291         BUG_ON(!net);
292 
293         return net_generic(net, ppp_net_id);
294 }
295 
296 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
297 static inline int proto_to_npindex(int proto)
298 {
299         switch (proto) {
300         case PPP_IP:
301                 return NP_IP;
302         case PPP_IPV6:
303                 return NP_IPV6;
304         case PPP_IPX:
305                 return NP_IPX;
306         case PPP_AT:
307                 return NP_AT;
308         case PPP_MPLS_UC:
309                 return NP_MPLS_UC;
310         case PPP_MPLS_MC:
311                 return NP_MPLS_MC;
312         }
313         return -EINVAL;
314 }
315 
316 /* Translates an NP index into a PPP protocol number */
317 static const int npindex_to_proto[NUM_NP] = {
318         PPP_IP,
319         PPP_IPV6,
320         PPP_IPX,
321         PPP_AT,
322         PPP_MPLS_UC,
323         PPP_MPLS_MC,
324 };
325 
326 /* Translates an ethertype into an NP index */
327 static inline int ethertype_to_npindex(int ethertype)
328 {
329         switch (ethertype) {
330         case ETH_P_IP:
331                 return NP_IP;
332         case ETH_P_IPV6:
333                 return NP_IPV6;
334         case ETH_P_IPX:
335                 return NP_IPX;
336         case ETH_P_PPPTALK:
337         case ETH_P_ATALK:
338                 return NP_AT;
339         case ETH_P_MPLS_UC:
340                 return NP_MPLS_UC;
341         case ETH_P_MPLS_MC:
342                 return NP_MPLS_MC;
343         }
344         return -1;
345 }
346 
347 /* Translates an NP index into an ethertype */
348 static const int npindex_to_ethertype[NUM_NP] = {
349         ETH_P_IP,
350         ETH_P_IPV6,
351         ETH_P_IPX,
352         ETH_P_PPPTALK,
353         ETH_P_MPLS_UC,
354         ETH_P_MPLS_MC,
355 };
356 
357 /*
358  * Locking shorthand.
359  */
360 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
361 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
362 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
363 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
364 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
365                                      ppp_recv_lock(ppp); } while (0)
366 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
367                                      ppp_xmit_unlock(ppp); } while (0)
368 
369 /*
370  * /dev/ppp device routines.
371  * The /dev/ppp device is used by pppd to control the ppp unit.
372  * It supports the read, write, ioctl and poll functions.
373  * Open instances of /dev/ppp can be in one of three states:
374  * unattached, attached to a ppp unit, or attached to a ppp channel.
375  */
376 static int ppp_open(struct inode *inode, struct file *file)
377 {
378         /*
379          * This could (should?) be enforced by the permissions on /dev/ppp.
380          */
381         if (!capable(CAP_NET_ADMIN))
382                 return -EPERM;
383         return 0;
384 }
385 
386 static int ppp_release(struct inode *unused, struct file *file)
387 {
388         struct ppp_file *pf = file->private_data;
389         struct ppp *ppp;
390 
391         if (pf) {
392                 file->private_data = NULL;
393                 if (pf->kind == INTERFACE) {
394                         ppp = PF_TO_PPP(pf);
395                         if (file == ppp->owner)
396                                 ppp_shutdown_interface(ppp);
397                 }
398                 if (atomic_dec_and_test(&pf->refcnt)) {
399                         switch (pf->kind) {
400                         case INTERFACE:
401                                 ppp_destroy_interface(PF_TO_PPP(pf));
402                                 break;
403                         case CHANNEL:
404                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
405                                 break;
406                         }
407                 }
408         }
409         return 0;
410 }
411 
412 static ssize_t ppp_read(struct file *file, char __user *buf,
413                         size_t count, loff_t *ppos)
414 {
415         struct ppp_file *pf = file->private_data;
416         DECLARE_WAITQUEUE(wait, current);
417         ssize_t ret;
418         struct sk_buff *skb = NULL;
419         struct iovec iov;
420         struct iov_iter to;
421 
422         ret = count;
423 
424         if (!pf)
425                 return -ENXIO;
426         add_wait_queue(&pf->rwait, &wait);
427         for (;;) {
428                 set_current_state(TASK_INTERRUPTIBLE);
429                 skb = skb_dequeue(&pf->rq);
430                 if (skb)
431                         break;
432                 ret = 0;
433                 if (pf->dead)
434                         break;
435                 if (pf->kind == INTERFACE) {
436                         /*
437                          * Return 0 (EOF) on an interface that has no
438                          * channels connected, unless it is looping
439                          * network traffic (demand mode).
440                          */
441                         struct ppp *ppp = PF_TO_PPP(pf);
442                         if (ppp->n_channels == 0 &&
443                             (ppp->flags & SC_LOOP_TRAFFIC) == 0)
444                                 break;
445                 }
446                 ret = -EAGAIN;
447                 if (file->f_flags & O_NONBLOCK)
448                         break;
449                 ret = -ERESTARTSYS;
450                 if (signal_pending(current))
451                         break;
452                 schedule();
453         }
454         set_current_state(TASK_RUNNING);
455         remove_wait_queue(&pf->rwait, &wait);
456 
457         if (!skb)
458                 goto out;
459 
460         ret = -EOVERFLOW;
461         if (skb->len > count)
462                 goto outf;
463         ret = -EFAULT;
464         iov.iov_base = buf;
465         iov.iov_len = count;
466         iov_iter_init(&to, READ, &iov, 1, count);
467         if (skb_copy_datagram_iter(skb, 0, &to, skb->len))
468                 goto outf;
469         ret = skb->len;
470 
471  outf:
472         kfree_skb(skb);
473  out:
474         return ret;
475 }
476 
477 static ssize_t ppp_write(struct file *file, const char __user *buf,
478                          size_t count, loff_t *ppos)
479 {
480         struct ppp_file *pf = file->private_data;
481         struct sk_buff *skb;
482         ssize_t ret;
483 
484         if (!pf)
485                 return -ENXIO;
486         ret = -ENOMEM;
487         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
488         if (!skb)
489                 goto out;
490         skb_reserve(skb, pf->hdrlen);
491         ret = -EFAULT;
492         if (copy_from_user(skb_put(skb, count), buf, count)) {
493                 kfree_skb(skb);
494                 goto out;
495         }
496 
497         skb_queue_tail(&pf->xq, skb);
498 
499         switch (pf->kind) {
500         case INTERFACE:
501                 ppp_xmit_process(PF_TO_PPP(pf));
502                 break;
503         case CHANNEL:
504                 ppp_channel_push(PF_TO_CHANNEL(pf));
505                 break;
506         }
507 
508         ret = count;
509 
510  out:
511         return ret;
512 }
513 
514 /* No kernel lock - fine */
515 static unsigned int ppp_poll(struct file *file, poll_table *wait)
516 {
517         struct ppp_file *pf = file->private_data;
518         unsigned int mask;
519 
520         if (!pf)
521                 return 0;
522         poll_wait(file, &pf->rwait, wait);
523         mask = POLLOUT | POLLWRNORM;
524         if (skb_peek(&pf->rq))
525                 mask |= POLLIN | POLLRDNORM;
526         if (pf->dead)
527                 mask |= POLLHUP;
528         else if (pf->kind == INTERFACE) {
529                 /* see comment in ppp_read */
530                 struct ppp *ppp = PF_TO_PPP(pf);
531                 if (ppp->n_channels == 0 &&
532                     (ppp->flags & SC_LOOP_TRAFFIC) == 0)
533                         mask |= POLLIN | POLLRDNORM;
534         }
535 
536         return mask;
537 }
538 
539 #ifdef CONFIG_PPP_FILTER
540 static int get_filter(void __user *arg, struct sock_filter **p)
541 {
542         struct sock_fprog uprog;
543         struct sock_filter *code = NULL;
544         int len;
545 
546         if (copy_from_user(&uprog, arg, sizeof(uprog)))
547                 return -EFAULT;
548 
549         if (!uprog.len) {
550                 *p = NULL;
551                 return 0;
552         }
553 
554         len = uprog.len * sizeof(struct sock_filter);
555         code = memdup_user(uprog.filter, len);
556         if (IS_ERR(code))
557                 return PTR_ERR(code);
558 
559         *p = code;
560         return uprog.len;
561 }
562 #endif /* CONFIG_PPP_FILTER */
563 
564 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
565 {
566         struct ppp_file *pf = file->private_data;
567         struct ppp *ppp;
568         int err = -EFAULT, val, val2, i;
569         struct ppp_idle idle;
570         struct npioctl npi;
571         int unit, cflags;
572         struct slcompress *vj;
573         void __user *argp = (void __user *)arg;
574         int __user *p = argp;
575 
576         if (!pf)
577                 return ppp_unattached_ioctl(current->nsproxy->net_ns,
578                                         pf, file, cmd, arg);
579 
580         if (cmd == PPPIOCDETACH) {
581                 /*
582                  * We have to be careful here... if the file descriptor
583                  * has been dup'd, we could have another process in the
584                  * middle of a poll using the same file *, so we had
585                  * better not free the interface data structures -
586                  * instead we fail the ioctl.  Even in this case, we
587                  * shut down the interface if we are the owner of it.
588                  * Actually, we should get rid of PPPIOCDETACH, userland
589                  * (i.e. pppd) could achieve the same effect by closing
590                  * this fd and reopening /dev/ppp.
591                  */
592                 err = -EINVAL;
593                 mutex_lock(&ppp_mutex);
594                 if (pf->kind == INTERFACE) {
595                         ppp = PF_TO_PPP(pf);
596                         if (file == ppp->owner)
597                                 ppp_shutdown_interface(ppp);
598                 }
599                 if (atomic_long_read(&file->f_count) < 2) {
600                         ppp_release(NULL, file);
601                         err = 0;
602                 } else
603                         pr_warn("PPPIOCDETACH file->f_count=%ld\n",
604                                 atomic_long_read(&file->f_count));
605                 mutex_unlock(&ppp_mutex);
606                 return err;
607         }
608 
609         if (pf->kind == CHANNEL) {
610                 struct channel *pch;
611                 struct ppp_channel *chan;
612 
613                 mutex_lock(&ppp_mutex);
614                 pch = PF_TO_CHANNEL(pf);
615 
616                 switch (cmd) {
617                 case PPPIOCCONNECT:
618                         if (get_user(unit, p))
619                                 break;
620                         err = ppp_connect_channel(pch, unit);
621                         break;
622 
623                 case PPPIOCDISCONN:
624                         err = ppp_disconnect_channel(pch);
625                         break;
626 
627                 default:
628                         down_read(&pch->chan_sem);
629                         chan = pch->chan;
630                         err = -ENOTTY;
631                         if (chan && chan->ops->ioctl)
632                                 err = chan->ops->ioctl(chan, cmd, arg);
633                         up_read(&pch->chan_sem);
634                 }
635                 mutex_unlock(&ppp_mutex);
636                 return err;
637         }
638 
639         if (pf->kind != INTERFACE) {
640                 /* can't happen */
641                 pr_err("PPP: not interface or channel??\n");
642                 return -EINVAL;
643         }
644 
645         mutex_lock(&ppp_mutex);
646         ppp = PF_TO_PPP(pf);
647         switch (cmd) {
648         case PPPIOCSMRU:
649                 if (get_user(val, p))
650                         break;
651                 ppp->mru = val;
652                 err = 0;
653                 break;
654 
655         case PPPIOCSFLAGS:
656                 if (get_user(val, p))
657                         break;
658                 ppp_lock(ppp);
659                 cflags = ppp->flags & ~val;
660 #ifdef CONFIG_PPP_MULTILINK
661                 if (!(ppp->flags & SC_MULTILINK) && (val & SC_MULTILINK))
662                         ppp->nextseq = 0;
663 #endif
664                 ppp->flags = val & SC_FLAG_BITS;
665                 ppp_unlock(ppp);
666                 if (cflags & SC_CCP_OPEN)
667                         ppp_ccp_closed(ppp);
668                 err = 0;
669                 break;
670 
671         case PPPIOCGFLAGS:
672                 val = ppp->flags | ppp->xstate | ppp->rstate;
673                 if (put_user(val, p))
674                         break;
675                 err = 0;
676                 break;
677 
678         case PPPIOCSCOMPRESS:
679                 err = ppp_set_compress(ppp, arg);
680                 break;
681 
682         case PPPIOCGUNIT:
683                 if (put_user(ppp->file.index, p))
684                         break;
685                 err = 0;
686                 break;
687 
688         case PPPIOCSDEBUG:
689                 if (get_user(val, p))
690                         break;
691                 ppp->debug = val;
692                 err = 0;
693                 break;
694 
695         case PPPIOCGDEBUG:
696                 if (put_user(ppp->debug, p))
697                         break;
698                 err = 0;
699                 break;
700 
701         case PPPIOCGIDLE:
702                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
703                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
704                 if (copy_to_user(argp, &idle, sizeof(idle)))
705                         break;
706                 err = 0;
707                 break;
708 
709         case PPPIOCSMAXCID:
710                 if (get_user(val, p))
711                         break;
712                 val2 = 15;
713                 if ((val >> 16) != 0) {
714                         val2 = val >> 16;
715                         val &= 0xffff;
716                 }
717                 vj = slhc_init(val2+1, val+1);
718                 if (!vj) {
719                         netdev_err(ppp->dev,
720                                    "PPP: no memory (VJ compressor)\n");
721                         err = -ENOMEM;
722                         break;
723                 }
724                 ppp_lock(ppp);
725                 if (ppp->vj)
726                         slhc_free(ppp->vj);
727                 ppp->vj = vj;
728                 ppp_unlock(ppp);
729                 err = 0;
730                 break;
731 
732         case PPPIOCGNPMODE:
733         case PPPIOCSNPMODE:
734                 if (copy_from_user(&npi, argp, sizeof(npi)))
735                         break;
736                 err = proto_to_npindex(npi.protocol);
737                 if (err < 0)
738                         break;
739                 i = err;
740                 if (cmd == PPPIOCGNPMODE) {
741                         err = -EFAULT;
742                         npi.mode = ppp->npmode[i];
743                         if (copy_to_user(argp, &npi, sizeof(npi)))
744                                 break;
745                 } else {
746                         ppp->npmode[i] = npi.mode;
747                         /* we may be able to transmit more packets now (??) */
748                         netif_wake_queue(ppp->dev);
749                 }
750                 err = 0;
751                 break;
752 
753 #ifdef CONFIG_PPP_FILTER
754         case PPPIOCSPASS:
755         {
756                 struct sock_filter *code;
757 
758                 err = get_filter(argp, &code);
759                 if (err >= 0) {
760                         struct bpf_prog *pass_filter = NULL;
761                         struct sock_fprog_kern fprog = {
762                                 .len = err,
763                                 .filter = code,
764                         };
765 
766                         err = 0;
767                         if (fprog.filter)
768                                 err = bpf_prog_create(&pass_filter, &fprog);
769                         if (!err) {
770                                 ppp_lock(ppp);
771                                 if (ppp->pass_filter)
772                                         bpf_prog_destroy(ppp->pass_filter);
773                                 ppp->pass_filter = pass_filter;
774                                 ppp_unlock(ppp);
775                         }
776                         kfree(code);
777                 }
778                 break;
779         }
780         case PPPIOCSACTIVE:
781         {
782                 struct sock_filter *code;
783 
784                 err = get_filter(argp, &code);
785                 if (err >= 0) {
786                         struct bpf_prog *active_filter = NULL;
787                         struct sock_fprog_kern fprog = {
788                                 .len = err,
789                                 .filter = code,
790                         };
791 
792                         err = 0;
793                         if (fprog.filter)
794                                 err = bpf_prog_create(&active_filter, &fprog);
795                         if (!err) {
796                                 ppp_lock(ppp);
797                                 if (ppp->active_filter)
798                                         bpf_prog_destroy(ppp->active_filter);
799                                 ppp->active_filter = active_filter;
800                                 ppp_unlock(ppp);
801                         }
802                         kfree(code);
803                 }
804                 break;
805         }
806 #endif /* CONFIG_PPP_FILTER */
807 
808 #ifdef CONFIG_PPP_MULTILINK
809         case PPPIOCSMRRU:
810                 if (get_user(val, p))
811                         break;
812                 ppp_recv_lock(ppp);
813                 ppp->mrru = val;
814                 ppp_recv_unlock(ppp);
815                 err = 0;
816                 break;
817 #endif /* CONFIG_PPP_MULTILINK */
818 
819         default:
820                 err = -ENOTTY;
821         }
822         mutex_unlock(&ppp_mutex);
823         return err;
824 }
825 
826 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
827                         struct file *file, unsigned int cmd, unsigned long arg)
828 {
829         int unit, err = -EFAULT;
830         struct ppp *ppp;
831         struct channel *chan;
832         struct ppp_net *pn;
833         int __user *p = (int __user *)arg;
834 
835         mutex_lock(&ppp_mutex);
836         switch (cmd) {
837         case PPPIOCNEWUNIT:
838                 /* Create a new ppp unit */
839                 if (get_user(unit, p))
840                         break;
841                 ppp = ppp_create_interface(net, unit, &err);
842                 if (!ppp)
843                         break;
844                 file->private_data = &ppp->file;
845                 ppp->owner = file;
846                 err = -EFAULT;
847                 if (put_user(ppp->file.index, p))
848                         break;
849                 err = 0;
850                 break;
851 
852         case PPPIOCATTACH:
853                 /* Attach to an existing ppp unit */
854                 if (get_user(unit, p))
855                         break;
856                 err = -ENXIO;
857                 pn = ppp_pernet(net);
858                 mutex_lock(&pn->all_ppp_mutex);
859                 ppp = ppp_find_unit(pn, unit);
860                 if (ppp) {
861                         atomic_inc(&ppp->file.refcnt);
862                         file->private_data = &ppp->file;
863                         err = 0;
864                 }
865                 mutex_unlock(&pn->all_ppp_mutex);
866                 break;
867 
868         case PPPIOCATTCHAN:
869                 if (get_user(unit, p))
870                         break;
871                 err = -ENXIO;
872                 pn = ppp_pernet(net);
873                 spin_lock_bh(&pn->all_channels_lock);
874                 chan = ppp_find_channel(pn, unit);
875                 if (chan) {
876                         atomic_inc(&chan->file.refcnt);
877                         file->private_data = &chan->file;
878                         err = 0;
879                 }
880                 spin_unlock_bh(&pn->all_channels_lock);
881                 break;
882 
883         default:
884                 err = -ENOTTY;
885         }
886         mutex_unlock(&ppp_mutex);
887         return err;
888 }
889 
890 static const struct file_operations ppp_device_fops = {
891         .owner          = THIS_MODULE,
892         .read           = ppp_read,
893         .write          = ppp_write,
894         .poll           = ppp_poll,
895         .unlocked_ioctl = ppp_ioctl,
896         .open           = ppp_open,
897         .release        = ppp_release,
898         .llseek         = noop_llseek,
899 };
900 
901 static __net_init int ppp_init_net(struct net *net)
902 {
903         struct ppp_net *pn = net_generic(net, ppp_net_id);
904 
905         idr_init(&pn->units_idr);
906         mutex_init(&pn->all_ppp_mutex);
907 
908         INIT_LIST_HEAD(&pn->all_channels);
909         INIT_LIST_HEAD(&pn->new_channels);
910 
911         spin_lock_init(&pn->all_channels_lock);
912 
913         return 0;
914 }
915 
916 static __net_exit void ppp_exit_net(struct net *net)
917 {
918         struct ppp_net *pn = net_generic(net, ppp_net_id);
919 
920         idr_destroy(&pn->units_idr);
921 }
922 
923 static struct pernet_operations ppp_net_ops = {
924         .init = ppp_init_net,
925         .exit = ppp_exit_net,
926         .id   = &ppp_net_id,
927         .size = sizeof(struct ppp_net),
928 };
929 
930 #define PPP_MAJOR       108
931 
932 /* Called at boot time if ppp is compiled into the kernel,
933    or at module load time (from init_module) if compiled as a module. */
934 static int __init ppp_init(void)
935 {
936         int err;
937 
938         pr_info("PPP generic driver version " PPP_VERSION "\n");
939 
940         err = register_pernet_device(&ppp_net_ops);
941         if (err) {
942                 pr_err("failed to register PPP pernet device (%d)\n", err);
943                 goto out;
944         }
945 
946         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
947         if (err) {
948                 pr_err("failed to register PPP device (%d)\n", err);
949                 goto out_net;
950         }
951 
952         ppp_class = class_create(THIS_MODULE, "ppp");
953         if (IS_ERR(ppp_class)) {
954                 err = PTR_ERR(ppp_class);
955                 goto out_chrdev;
956         }
957 
958         /* not a big deal if we fail here :-) */
959         device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
960 
961         return 0;
962 
963 out_chrdev:
964         unregister_chrdev(PPP_MAJOR, "ppp");
965 out_net:
966         unregister_pernet_device(&ppp_net_ops);
967 out:
968         return err;
969 }
970 
971 /*
972  * Network interface unit routines.
973  */
974 static netdev_tx_t
975 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
976 {
977         struct ppp *ppp = netdev_priv(dev);
978         int npi, proto;
979         unsigned char *pp;
980 
981         npi = ethertype_to_npindex(ntohs(skb->protocol));
982         if (npi < 0)
983                 goto outf;
984 
985         /* Drop, accept or reject the packet */
986         switch (ppp->npmode[npi]) {
987         case NPMODE_PASS:
988                 break;
989         case NPMODE_QUEUE:
990                 /* it would be nice to have a way to tell the network
991                    system to queue this one up for later. */
992                 goto outf;
993         case NPMODE_DROP:
994         case NPMODE_ERROR:
995                 goto outf;
996         }
997 
998         /* Put the 2-byte PPP protocol number on the front,
999            making sure there is room for the address and control fields. */
1000         if (skb_cow_head(skb, PPP_HDRLEN))
1001                 goto outf;
1002 
1003         pp = skb_push(skb, 2);
1004         proto = npindex_to_proto[npi];
1005         put_unaligned_be16(proto, pp);
1006 
1007         skb_queue_tail(&ppp->file.xq, skb);
1008         ppp_xmit_process(ppp);
1009         return NETDEV_TX_OK;
1010 
1011  outf:
1012         kfree_skb(skb);
1013         ++dev->stats.tx_dropped;
1014         return NETDEV_TX_OK;
1015 }
1016 
1017 static int
1018 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
1019 {
1020         struct ppp *ppp = netdev_priv(dev);
1021         int err = -EFAULT;
1022         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
1023         struct ppp_stats stats;
1024         struct ppp_comp_stats cstats;
1025         char *vers;
1026 
1027         switch (cmd) {
1028         case SIOCGPPPSTATS:
1029                 ppp_get_stats(ppp, &stats);
1030                 if (copy_to_user(addr, &stats, sizeof(stats)))
1031                         break;
1032                 err = 0;
1033                 break;
1034 
1035         case SIOCGPPPCSTATS:
1036                 memset(&cstats, 0, sizeof(cstats));
1037                 if (ppp->xc_state)
1038                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
1039                 if (ppp->rc_state)
1040                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
1041                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
1042                         break;
1043                 err = 0;
1044                 break;
1045 
1046         case SIOCGPPPVER:
1047                 vers = PPP_VERSION;
1048                 if (copy_to_user(addr, vers, strlen(vers) + 1))
1049                         break;
1050                 err = 0;
1051                 break;
1052 
1053         default:
1054                 err = -EINVAL;
1055         }
1056 
1057         return err;
1058 }
1059 
1060 static struct rtnl_link_stats64*
1061 ppp_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats64)
1062 {
1063         struct ppp *ppp = netdev_priv(dev);
1064 
1065         ppp_recv_lock(ppp);
1066         stats64->rx_packets = ppp->stats64.rx_packets;
1067         stats64->rx_bytes   = ppp->stats64.rx_bytes;
1068         ppp_recv_unlock(ppp);
1069 
1070         ppp_xmit_lock(ppp);
1071         stats64->tx_packets = ppp->stats64.tx_packets;
1072         stats64->tx_bytes   = ppp->stats64.tx_bytes;
1073         ppp_xmit_unlock(ppp);
1074 
1075         stats64->rx_errors        = dev->stats.rx_errors;
1076         stats64->tx_errors        = dev->stats.tx_errors;
1077         stats64->rx_dropped       = dev->stats.rx_dropped;
1078         stats64->tx_dropped       = dev->stats.tx_dropped;
1079         stats64->rx_length_errors = dev->stats.rx_length_errors;
1080 
1081         return stats64;
1082 }
1083 
1084 static struct lock_class_key ppp_tx_busylock;
1085 static int ppp_dev_init(struct net_device *dev)
1086 {
1087         dev->qdisc_tx_busylock = &ppp_tx_busylock;
1088         return 0;
1089 }
1090 
1091 static const struct net_device_ops ppp_netdev_ops = {
1092         .ndo_init        = ppp_dev_init,
1093         .ndo_start_xmit  = ppp_start_xmit,
1094         .ndo_do_ioctl    = ppp_net_ioctl,
1095         .ndo_get_stats64 = ppp_get_stats64,
1096 };
1097 
1098 static void ppp_setup(struct net_device *dev)
1099 {
1100         dev->netdev_ops = &ppp_netdev_ops;
1101         dev->hard_header_len = PPP_HDRLEN;
1102         dev->mtu = PPP_MRU;
1103         dev->addr_len = 0;
1104         dev->tx_queue_len = 3;
1105         dev->type = ARPHRD_PPP;
1106         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1107         dev->features |= NETIF_F_NETNS_LOCAL;
1108         netif_keep_dst(dev);
1109 }
1110 
1111 /*
1112  * Transmit-side routines.
1113  */
1114 
1115 /*
1116  * Called to do any work queued up on the transmit side
1117  * that can now be done.
1118  */
1119 static void
1120 ppp_xmit_process(struct ppp *ppp)
1121 {
1122         struct sk_buff *skb;
1123 
1124         ppp_xmit_lock(ppp);
1125         if (!ppp->closing) {
1126                 ppp_push(ppp);
1127                 while (!ppp->xmit_pending &&
1128                        (skb = skb_dequeue(&ppp->file.xq)))
1129                         ppp_send_frame(ppp, skb);
1130                 /* If there's no work left to do, tell the core net
1131                    code that we can accept some more. */
1132                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1133                         netif_wake_queue(ppp->dev);
1134                 else
1135                         netif_stop_queue(ppp->dev);
1136         }
1137         ppp_xmit_unlock(ppp);
1138 }
1139 
1140 static inline struct sk_buff *
1141 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1142 {
1143         struct sk_buff *new_skb;
1144         int len;
1145         int new_skb_size = ppp->dev->mtu +
1146                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1147         int compressor_skb_size = ppp->dev->mtu +
1148                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1149         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1150         if (!new_skb) {
1151                 if (net_ratelimit())
1152                         netdev_err(ppp->dev, "PPP: no memory (comp pkt)\n");
1153                 return NULL;
1154         }
1155         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1156                 skb_reserve(new_skb,
1157                             ppp->dev->hard_header_len - PPP_HDRLEN);
1158 
1159         /* compressor still expects A/C bytes in hdr */
1160         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1161                                    new_skb->data, skb->len + 2,
1162                                    compressor_skb_size);
1163         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1164                 consume_skb(skb);
1165                 skb = new_skb;
1166                 skb_put(skb, len);
1167                 skb_pull(skb, 2);       /* pull off A/C bytes */
1168         } else if (len == 0) {
1169                 /* didn't compress, or CCP not up yet */
1170                 consume_skb(new_skb);
1171                 new_skb = skb;
1172         } else {
1173                 /*
1174                  * (len < 0)
1175                  * MPPE requires that we do not send unencrypted
1176                  * frames.  The compressor will return -1 if we
1177                  * should drop the frame.  We cannot simply test
1178                  * the compress_proto because MPPE and MPPC share
1179                  * the same number.
1180                  */
1181                 if (net_ratelimit())
1182                         netdev_err(ppp->dev, "ppp: compressor dropped pkt\n");
1183                 kfree_skb(skb);
1184                 consume_skb(new_skb);
1185                 new_skb = NULL;
1186         }
1187         return new_skb;
1188 }
1189 
1190 /*
1191  * Compress and send a frame.
1192  * The caller should have locked the xmit path,
1193  * and xmit_pending should be 0.
1194  */
1195 static void
1196 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1197 {
1198         int proto = PPP_PROTO(skb);
1199         struct sk_buff *new_skb;
1200         int len;
1201         unsigned char *cp;
1202 
1203         if (proto < 0x8000) {
1204 #ifdef CONFIG_PPP_FILTER
1205                 /* check if we should pass this packet */
1206                 /* the filter instructions are constructed assuming
1207                    a four-byte PPP header on each packet */
1208                 *skb_push(skb, 2) = 1;
1209                 if (ppp->pass_filter &&
1210                     BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
1211                         if (ppp->debug & 1)
1212                                 netdev_printk(KERN_DEBUG, ppp->dev,
1213                                               "PPP: outbound frame "
1214                                               "not passed\n");
1215                         kfree_skb(skb);
1216                         return;
1217                 }
1218                 /* if this packet passes the active filter, record the time */
1219                 if (!(ppp->active_filter &&
1220                       BPF_PROG_RUN(ppp->active_filter, skb) == 0))
1221                         ppp->last_xmit = jiffies;
1222                 skb_pull(skb, 2);
1223 #else
1224                 /* for data packets, record the time */
1225                 ppp->last_xmit = jiffies;
1226 #endif /* CONFIG_PPP_FILTER */
1227         }
1228 
1229         ++ppp->stats64.tx_packets;
1230         ppp->stats64.tx_bytes += skb->len - 2;
1231 
1232         switch (proto) {
1233         case PPP_IP:
1234                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1235                         break;
1236                 /* try to do VJ TCP header compression */
1237                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1238                                     GFP_ATOMIC);
1239                 if (!new_skb) {
1240                         netdev_err(ppp->dev, "PPP: no memory (VJ comp pkt)\n");
1241                         goto drop;
1242                 }
1243                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1244                 cp = skb->data + 2;
1245                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1246                                     new_skb->data + 2, &cp,
1247                                     !(ppp->flags & SC_NO_TCP_CCID));
1248                 if (cp == skb->data + 2) {
1249                         /* didn't compress */
1250                         consume_skb(new_skb);
1251                 } else {
1252                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1253                                 proto = PPP_VJC_COMP;
1254                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1255                         } else {
1256                                 proto = PPP_VJC_UNCOMP;
1257                                 cp[0] = skb->data[2];
1258                         }
1259                         consume_skb(skb);
1260                         skb = new_skb;
1261                         cp = skb_put(skb, len + 2);
1262                         cp[0] = 0;
1263                         cp[1] = proto;
1264                 }
1265                 break;
1266 
1267         case PPP_CCP:
1268                 /* peek at outbound CCP frames */
1269                 ppp_ccp_peek(ppp, skb, 0);
1270                 break;
1271         }
1272 
1273         /* try to do packet compression */
1274         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state &&
1275             proto != PPP_LCP && proto != PPP_CCP) {
1276                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1277                         if (net_ratelimit())
1278                                 netdev_err(ppp->dev,
1279                                            "ppp: compression required but "
1280                                            "down - pkt dropped.\n");
1281                         goto drop;
1282                 }
1283                 skb = pad_compress_skb(ppp, skb);
1284                 if (!skb)
1285                         goto drop;
1286         }
1287 
1288         /*
1289          * If we are waiting for traffic (demand dialling),
1290          * queue it up for pppd to receive.
1291          */
1292         if (ppp->flags & SC_LOOP_TRAFFIC) {
1293                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1294                         goto drop;
1295                 skb_queue_tail(&ppp->file.rq, skb);
1296                 wake_up_interruptible(&ppp->file.rwait);
1297                 return;
1298         }
1299 
1300         ppp->xmit_pending = skb;
1301         ppp_push(ppp);
1302         return;
1303 
1304  drop:
1305         kfree_skb(skb);
1306         ++ppp->dev->stats.tx_errors;
1307 }
1308 
1309 /*
1310  * Try to send the frame in xmit_pending.
1311  * The caller should have the xmit path locked.
1312  */
1313 static void
1314 ppp_push(struct ppp *ppp)
1315 {
1316         struct list_head *list;
1317         struct channel *pch;
1318         struct sk_buff *skb = ppp->xmit_pending;
1319 
1320         if (!skb)
1321                 return;
1322 
1323         list = &ppp->channels;
1324         if (list_empty(list)) {
1325                 /* nowhere to send the packet, just drop it */
1326                 ppp->xmit_pending = NULL;
1327                 kfree_skb(skb);
1328                 return;
1329         }
1330 
1331         if ((ppp->flags & SC_MULTILINK) == 0) {
1332                 /* not doing multilink: send it down the first channel */
1333                 list = list->next;
1334                 pch = list_entry(list, struct channel, clist);
1335 
1336                 spin_lock_bh(&pch->downl);
1337                 if (pch->chan) {
1338                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1339                                 ppp->xmit_pending = NULL;
1340                 } else {
1341                         /* channel got unregistered */
1342                         kfree_skb(skb);
1343                         ppp->xmit_pending = NULL;
1344                 }
1345                 spin_unlock_bh(&pch->downl);
1346                 return;
1347         }
1348 
1349 #ifdef CONFIG_PPP_MULTILINK
1350         /* Multilink: fragment the packet over as many links
1351            as can take the packet at the moment. */
1352         if (!ppp_mp_explode(ppp, skb))
1353                 return;
1354 #endif /* CONFIG_PPP_MULTILINK */
1355 
1356         ppp->xmit_pending = NULL;
1357         kfree_skb(skb);
1358 }
1359 
1360 #ifdef CONFIG_PPP_MULTILINK
1361 static bool mp_protocol_compress __read_mostly = true;
1362 module_param(mp_protocol_compress, bool, S_IRUGO | S_IWUSR);
1363 MODULE_PARM_DESC(mp_protocol_compress,
1364                  "compress protocol id in multilink fragments");
1365 
1366 /*
1367  * Divide a packet to be transmitted into fragments and
1368  * send them out the individual links.
1369  */
1370 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1371 {
1372         int len, totlen;
1373         int i, bits, hdrlen, mtu;
1374         int flen;
1375         int navail, nfree, nzero;
1376         int nbigger;
1377         int totspeed;
1378         int totfree;
1379         unsigned char *p, *q;
1380         struct list_head *list;
1381         struct channel *pch;
1382         struct sk_buff *frag;
1383         struct ppp_channel *chan;
1384 
1385         totspeed = 0; /*total bitrate of the bundle*/
1386         nfree = 0; /* # channels which have no packet already queued */
1387         navail = 0; /* total # of usable channels (not deregistered) */
1388         nzero = 0; /* number of channels with zero speed associated*/
1389         totfree = 0; /*total # of channels available and
1390                                   *having no queued packets before
1391                                   *starting the fragmentation*/
1392 
1393         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1394         i = 0;
1395         list_for_each_entry(pch, &ppp->channels, clist) {
1396                 if (pch->chan) {
1397                         pch->avail = 1;
1398                         navail++;
1399                         pch->speed = pch->chan->speed;
1400                 } else {
1401                         pch->avail = 0;
1402                 }
1403                 if (pch->avail) {
1404                         if (skb_queue_empty(&pch->file.xq) ||
1405                                 !pch->had_frag) {
1406                                         if (pch->speed == 0)
1407                                                 nzero++;
1408                                         else
1409                                                 totspeed += pch->speed;
1410 
1411                                         pch->avail = 2;
1412                                         ++nfree;
1413                                         ++totfree;
1414                                 }
1415                         if (!pch->had_frag && i < ppp->nxchan)
1416                                 ppp->nxchan = i;
1417                 }
1418                 ++i;
1419         }
1420         /*
1421          * Don't start sending this packet unless at least half of
1422          * the channels are free.  This gives much better TCP
1423          * performance if we have a lot of channels.
1424          */
1425         if (nfree == 0 || nfree < navail / 2)
1426                 return 0; /* can't take now, leave it in xmit_pending */
1427 
1428         /* Do protocol field compression */
1429         p = skb->data;
1430         len = skb->len;
1431         if (*p == 0 && mp_protocol_compress) {
1432                 ++p;
1433                 --len;
1434         }
1435 
1436         totlen = len;
1437         nbigger = len % nfree;
1438 
1439         /* skip to the channel after the one we last used
1440            and start at that one */
1441         list = &ppp->channels;
1442         for (i = 0; i < ppp->nxchan; ++i) {
1443                 list = list->next;
1444                 if (list == &ppp->channels) {
1445                         i = 0;
1446                         break;
1447                 }
1448         }
1449 
1450         /* create a fragment for each channel */
1451         bits = B;
1452         while (len > 0) {
1453                 list = list->next;
1454                 if (list == &ppp->channels) {
1455                         i = 0;
1456                         continue;
1457                 }
1458                 pch = list_entry(list, struct channel, clist);
1459                 ++i;
1460                 if (!pch->avail)
1461                         continue;
1462 
1463                 /*
1464                  * Skip this channel if it has a fragment pending already and
1465                  * we haven't given a fragment to all of the free channels.
1466                  */
1467                 if (pch->avail == 1) {
1468                         if (nfree > 0)
1469                                 continue;
1470                 } else {
1471                         pch->avail = 1;
1472                 }
1473 
1474                 /* check the channel's mtu and whether it is still attached. */
1475                 spin_lock_bh(&pch->downl);
1476                 if (pch->chan == NULL) {
1477                         /* can't use this channel, it's being deregistered */
1478                         if (pch->speed == 0)
1479                                 nzero--;
1480                         else
1481                                 totspeed -= pch->speed;
1482 
1483                         spin_unlock_bh(&pch->downl);
1484                         pch->avail = 0;
1485                         totlen = len;
1486                         totfree--;
1487                         nfree--;
1488                         if (--navail == 0)
1489                                 break;
1490                         continue;
1491                 }
1492 
1493                 /*
1494                 *if the channel speed is not set divide
1495                 *the packet evenly among the free channels;
1496                 *otherwise divide it according to the speed
1497                 *of the channel we are going to transmit on
1498                 */
1499                 flen = len;
1500                 if (nfree > 0) {
1501                         if (pch->speed == 0) {
1502                                 flen = len/nfree;
1503                                 if (nbigger > 0) {
1504                                         flen++;
1505                                         nbigger--;
1506                                 }
1507                         } else {
1508                                 flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
1509                                         ((totspeed*totfree)/pch->speed)) - hdrlen;
1510                                 if (nbigger > 0) {
1511                                         flen += ((totfree - nzero)*pch->speed)/totspeed;
1512                                         nbigger -= ((totfree - nzero)*pch->speed)/
1513                                                         totspeed;
1514                                 }
1515                         }
1516                         nfree--;
1517                 }
1518 
1519                 /*
1520                  *check if we are on the last channel or
1521                  *we exceded the length of the data to
1522                  *fragment
1523                  */
1524                 if ((nfree <= 0) || (flen > len))
1525                         flen = len;
1526                 /*
1527                  *it is not worth to tx on slow channels:
1528                  *in that case from the resulting flen according to the
1529                  *above formula will be equal or less than zero.
1530                  *Skip the channel in this case
1531                  */
1532                 if (flen <= 0) {
1533                         pch->avail = 2;
1534                         spin_unlock_bh(&pch->downl);
1535                         continue;
1536                 }
1537 
1538                 /*
1539                  * hdrlen includes the 2-byte PPP protocol field, but the
1540                  * MTU counts only the payload excluding the protocol field.
1541                  * (RFC1661 Section 2)
1542                  */
1543                 mtu = pch->chan->mtu - (hdrlen - 2);
1544                 if (mtu < 4)
1545                         mtu = 4;
1546                 if (flen > mtu)
1547                         flen = mtu;
1548                 if (flen == len)
1549                         bits |= E;
1550                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1551                 if (!frag)
1552                         goto noskb;
1553                 q = skb_put(frag, flen + hdrlen);
1554 
1555                 /* make the MP header */
1556                 put_unaligned_be16(PPP_MP, q);
1557                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1558                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1559                         q[3] = ppp->nxseq;
1560                 } else {
1561                         q[2] = bits;
1562                         q[3] = ppp->nxseq >> 16;
1563                         q[4] = ppp->nxseq >> 8;
1564                         q[5] = ppp->nxseq;
1565                 }
1566 
1567                 memcpy(q + hdrlen, p, flen);
1568 
1569                 /* try to send it down the channel */
1570                 chan = pch->chan;
1571                 if (!skb_queue_empty(&pch->file.xq) ||
1572                         !chan->ops->start_xmit(chan, frag))
1573                         skb_queue_tail(&pch->file.xq, frag);
1574                 pch->had_frag = 1;
1575                 p += flen;
1576                 len -= flen;
1577                 ++ppp->nxseq;
1578                 bits = 0;
1579                 spin_unlock_bh(&pch->downl);
1580         }
1581         ppp->nxchan = i;
1582 
1583         return 1;
1584 
1585  noskb:
1586         spin_unlock_bh(&pch->downl);
1587         if (ppp->debug & 1)
1588                 netdev_err(ppp->dev, "PPP: no memory (fragment)\n");
1589         ++ppp->dev->stats.tx_errors;
1590         ++ppp->nxseq;
1591         return 1;       /* abandon the frame */
1592 }
1593 #endif /* CONFIG_PPP_MULTILINK */
1594 
1595 /*
1596  * Try to send data out on a channel.
1597  */
1598 static void
1599 ppp_channel_push(struct channel *pch)
1600 {
1601         struct sk_buff *skb;
1602         struct ppp *ppp;
1603 
1604         spin_lock_bh(&pch->downl);
1605         if (pch->chan) {
1606                 while (!skb_queue_empty(&pch->file.xq)) {
1607                         skb = skb_dequeue(&pch->file.xq);
1608                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1609                                 /* put the packet back and try again later */
1610                                 skb_queue_head(&pch->file.xq, skb);
1611                                 break;
1612                         }
1613                 }
1614         } else {
1615                 /* channel got deregistered */
1616                 skb_queue_purge(&pch->file.xq);
1617         }
1618         spin_unlock_bh(&pch->downl);
1619         /* see if there is anything from the attached unit to be sent */
1620         if (skb_queue_empty(&pch->file.xq)) {
1621                 read_lock_bh(&pch->upl);
1622                 ppp = pch->ppp;
1623                 if (ppp)
1624                         ppp_xmit_process(ppp);
1625                 read_unlock_bh(&pch->upl);
1626         }
1627 }
1628 
1629 /*
1630  * Receive-side routines.
1631  */
1632 
1633 struct ppp_mp_skb_parm {
1634         u32             sequence;
1635         u8              BEbits;
1636 };
1637 #define PPP_MP_CB(skb)  ((struct ppp_mp_skb_parm *)((skb)->cb))
1638 
1639 static inline void
1640 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1641 {
1642         ppp_recv_lock(ppp);
1643         if (!ppp->closing)
1644                 ppp_receive_frame(ppp, skb, pch);
1645         else
1646                 kfree_skb(skb);
1647         ppp_recv_unlock(ppp);
1648 }
1649 
1650 void
1651 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1652 {
1653         struct channel *pch = chan->ppp;
1654         int proto;
1655 
1656         if (!pch) {
1657                 kfree_skb(skb);
1658                 return;
1659         }
1660 
1661         read_lock_bh(&pch->upl);
1662         if (!pskb_may_pull(skb, 2)) {
1663                 kfree_skb(skb);
1664                 if (pch->ppp) {
1665                         ++pch->ppp->dev->stats.rx_length_errors;
1666                         ppp_receive_error(pch->ppp);
1667                 }
1668                 goto done;
1669         }
1670 
1671         proto = PPP_PROTO(skb);
1672         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1673                 /* put it on the channel queue */
1674                 skb_queue_tail(&pch->file.rq, skb);
1675                 /* drop old frames if queue too long */
1676                 while (pch->file.rq.qlen > PPP_MAX_RQLEN &&
1677                        (skb = skb_dequeue(&pch->file.rq)))
1678                         kfree_skb(skb);
1679                 wake_up_interruptible(&pch->file.rwait);
1680         } else {
1681                 ppp_do_recv(pch->ppp, skb, pch);
1682         }
1683 
1684 done:
1685         read_unlock_bh(&pch->upl);
1686 }
1687 
1688 /* Put a 0-length skb in the receive queue as an error indication */
1689 void
1690 ppp_input_error(struct ppp_channel *chan, int code)
1691 {
1692         struct channel *pch = chan->ppp;
1693         struct sk_buff *skb;
1694 
1695         if (!pch)
1696                 return;
1697 
1698         read_lock_bh(&pch->upl);
1699         if (pch->ppp) {
1700                 skb = alloc_skb(0, GFP_ATOMIC);
1701                 if (skb) {
1702                         skb->len = 0;           /* probably unnecessary */
1703                         skb->cb[0] = code;
1704                         ppp_do_recv(pch->ppp, skb, pch);
1705                 }
1706         }
1707         read_unlock_bh(&pch->upl);
1708 }
1709 
1710 /*
1711  * We come in here to process a received frame.
1712  * The receive side of the ppp unit is locked.
1713  */
1714 static void
1715 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1716 {
1717         /* note: a 0-length skb is used as an error indication */
1718         if (skb->len > 0) {
1719 #ifdef CONFIG_PPP_MULTILINK
1720                 /* XXX do channel-level decompression here */
1721                 if (PPP_PROTO(skb) == PPP_MP)
1722                         ppp_receive_mp_frame(ppp, skb, pch);
1723                 else
1724 #endif /* CONFIG_PPP_MULTILINK */
1725                         ppp_receive_nonmp_frame(ppp, skb);
1726         } else {
1727                 kfree_skb(skb);
1728                 ppp_receive_error(ppp);
1729         }
1730 }
1731 
1732 static void
1733 ppp_receive_error(struct ppp *ppp)
1734 {
1735         ++ppp->dev->stats.rx_errors;
1736         if (ppp->vj)
1737                 slhc_toss(ppp->vj);
1738 }
1739 
1740 static void
1741 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1742 {
1743         struct sk_buff *ns;
1744         int proto, len, npi;
1745 
1746         /*
1747          * Decompress the frame, if compressed.
1748          * Note that some decompressors need to see uncompressed frames
1749          * that come in as well as compressed frames.
1750          */
1751         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN) &&
1752             (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1753                 skb = ppp_decompress_frame(ppp, skb);
1754 
1755         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1756                 goto err;
1757 
1758         proto = PPP_PROTO(skb);
1759         switch (proto) {
1760         case PPP_VJC_COMP:
1761                 /* decompress VJ compressed packets */
1762                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1763                         goto err;
1764 
1765                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1766                         /* copy to a new sk_buff with more tailroom */
1767                         ns = dev_alloc_skb(skb->len + 128);
1768                         if (!ns) {
1769                                 netdev_err(ppp->dev, "PPP: no memory "
1770                                            "(VJ decomp)\n");
1771                                 goto err;
1772                         }
1773                         skb_reserve(ns, 2);
1774                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1775                         consume_skb(skb);
1776                         skb = ns;
1777                 }
1778                 else
1779                         skb->ip_summed = CHECKSUM_NONE;
1780 
1781                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1782                 if (len <= 0) {
1783                         netdev_printk(KERN_DEBUG, ppp->dev,
1784                                       "PPP: VJ decompression error\n");
1785                         goto err;
1786                 }
1787                 len += 2;
1788                 if (len > skb->len)
1789                         skb_put(skb, len - skb->len);
1790                 else if (len < skb->len)
1791                         skb_trim(skb, len);
1792                 proto = PPP_IP;
1793                 break;
1794 
1795         case PPP_VJC_UNCOMP:
1796                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1797                         goto err;
1798 
1799                 /* Until we fix the decompressor need to make sure
1800                  * data portion is linear.
1801                  */
1802                 if (!pskb_may_pull(skb, skb->len))
1803                         goto err;
1804 
1805                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1806                         netdev_err(ppp->dev, "PPP: VJ uncompressed error\n");
1807                         goto err;
1808                 }
1809                 proto = PPP_IP;
1810                 break;
1811 
1812         case PPP_CCP:
1813                 ppp_ccp_peek(ppp, skb, 1);
1814                 break;
1815         }
1816 
1817         ++ppp->stats64.rx_packets;
1818         ppp->stats64.rx_bytes += skb->len - 2;
1819 
1820         npi = proto_to_npindex(proto);
1821         if (npi < 0) {
1822                 /* control or unknown frame - pass it to pppd */
1823                 skb_queue_tail(&ppp->file.rq, skb);
1824                 /* limit queue length by dropping old frames */
1825                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN &&
1826                        (skb = skb_dequeue(&ppp->file.rq)))
1827                         kfree_skb(skb);
1828                 /* wake up any process polling or blocking on read */
1829                 wake_up_interruptible(&ppp->file.rwait);
1830 
1831         } else {
1832                 /* network protocol frame - give it to the kernel */
1833 
1834 #ifdef CONFIG_PPP_FILTER
1835                 /* check if the packet passes the pass and active filters */
1836                 /* the filter instructions are constructed assuming
1837                    a four-byte PPP header on each packet */
1838                 if (ppp->pass_filter || ppp->active_filter) {
1839                         if (skb_unclone(skb, GFP_ATOMIC))
1840                                 goto err;
1841 
1842                         *skb_push(skb, 2) = 0;
1843                         if (ppp->pass_filter &&
1844                             BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
1845                                 if (ppp->debug & 1)
1846                                         netdev_printk(KERN_DEBUG, ppp->dev,
1847                                                       "PPP: inbound frame "
1848                                                       "not passed\n");
1849                                 kfree_skb(skb);
1850                                 return;
1851                         }
1852                         if (!(ppp->active_filter &&
1853                               BPF_PROG_RUN(ppp->active_filter, skb) == 0))
1854                                 ppp->last_recv = jiffies;
1855                         __skb_pull(skb, 2);
1856                 } else
1857 #endif /* CONFIG_PPP_FILTER */
1858                         ppp->last_recv = jiffies;
1859 
1860                 if ((ppp->dev->flags & IFF_UP) == 0 ||
1861                     ppp->npmode[npi] != NPMODE_PASS) {
1862                         kfree_skb(skb);
1863                 } else {
1864                         /* chop off protocol */
1865                         skb_pull_rcsum(skb, 2);
1866                         skb->dev = ppp->dev;
1867                         skb->protocol = htons(npindex_to_ethertype[npi]);
1868                         skb_reset_mac_header(skb);
1869                         netif_rx(skb);
1870                 }
1871         }
1872         return;
1873 
1874  err:
1875         kfree_skb(skb);
1876         ppp_receive_error(ppp);
1877 }
1878 
1879 static struct sk_buff *
1880 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1881 {
1882         int proto = PPP_PROTO(skb);
1883         struct sk_buff *ns;
1884         int len;
1885 
1886         /* Until we fix all the decompressor's need to make sure
1887          * data portion is linear.
1888          */
1889         if (!pskb_may_pull(skb, skb->len))
1890                 goto err;
1891 
1892         if (proto == PPP_COMP) {
1893                 int obuff_size;
1894 
1895                 switch(ppp->rcomp->compress_proto) {
1896                 case CI_MPPE:
1897                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1898                         break;
1899                 default:
1900                         obuff_size = ppp->mru + PPP_HDRLEN;
1901                         break;
1902                 }
1903 
1904                 ns = dev_alloc_skb(obuff_size);
1905                 if (!ns) {
1906                         netdev_err(ppp->dev, "ppp_decompress_frame: "
1907                                    "no memory\n");
1908                         goto err;
1909                 }
1910                 /* the decompressor still expects the A/C bytes in the hdr */
1911                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1912                                 skb->len + 2, ns->data, obuff_size);
1913                 if (len < 0) {
1914                         /* Pass the compressed frame to pppd as an
1915                            error indication. */
1916                         if (len == DECOMP_FATALERROR)
1917                                 ppp->rstate |= SC_DC_FERROR;
1918                         kfree_skb(ns);
1919                         goto err;
1920                 }
1921 
1922                 consume_skb(skb);
1923                 skb = ns;
1924                 skb_put(skb, len);
1925                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1926 
1927         } else {
1928                 /* Uncompressed frame - pass to decompressor so it
1929                    can update its dictionary if necessary. */
1930                 if (ppp->rcomp->incomp)
1931                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1932                                            skb->len + 2);
1933         }
1934 
1935         return skb;
1936 
1937  err:
1938         ppp->rstate |= SC_DC_ERROR;
1939         ppp_receive_error(ppp);
1940         return skb;
1941 }
1942 
1943 #ifdef CONFIG_PPP_MULTILINK
1944 /*
1945  * Receive a multilink frame.
1946  * We put it on the reconstruction queue and then pull off
1947  * as many completed frames as we can.
1948  */
1949 static void
1950 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1951 {
1952         u32 mask, seq;
1953         struct channel *ch;
1954         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1955 
1956         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1957                 goto err;               /* no good, throw it away */
1958 
1959         /* Decode sequence number and begin/end bits */
1960         if (ppp->flags & SC_MP_SHORTSEQ) {
1961                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1962                 mask = 0xfff;
1963         } else {
1964                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1965                 mask = 0xffffff;
1966         }
1967         PPP_MP_CB(skb)->BEbits = skb->data[2];
1968         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1969 
1970         /*
1971          * Do protocol ID decompression on the first fragment of each packet.
1972          */
1973         if ((PPP_MP_CB(skb)->BEbits & B) && (skb->data[0] & 1))
1974                 *skb_push(skb, 1) = 0;
1975 
1976         /*
1977          * Expand sequence number to 32 bits, making it as close
1978          * as possible to ppp->minseq.
1979          */
1980         seq |= ppp->minseq & ~mask;
1981         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1982                 seq += mask + 1;
1983         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1984                 seq -= mask + 1;        /* should never happen */
1985         PPP_MP_CB(skb)->sequence = seq;
1986         pch->lastseq = seq;
1987 
1988         /*
1989          * If this packet comes before the next one we were expecting,
1990          * drop it.
1991          */
1992         if (seq_before(seq, ppp->nextseq)) {
1993                 kfree_skb(skb);
1994                 ++ppp->dev->stats.rx_dropped;
1995                 ppp_receive_error(ppp);
1996                 return;
1997         }
1998 
1999         /*
2000          * Reevaluate minseq, the minimum over all channels of the
2001          * last sequence number received on each channel.  Because of
2002          * the increasing sequence number rule, we know that any fragment
2003          * before `minseq' which hasn't arrived is never going to arrive.
2004          * The list of channels can't change because we have the receive
2005          * side of the ppp unit locked.
2006          */
2007         list_for_each_entry(ch, &ppp->channels, clist) {
2008                 if (seq_before(ch->lastseq, seq))
2009                         seq = ch->lastseq;
2010         }
2011         if (seq_before(ppp->minseq, seq))
2012                 ppp->minseq = seq;
2013 
2014         /* Put the fragment on the reconstruction queue */
2015         ppp_mp_insert(ppp, skb);
2016 
2017         /* If the queue is getting long, don't wait any longer for packets
2018            before the start of the queue. */
2019         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
2020                 struct sk_buff *mskb = skb_peek(&ppp->mrq);
2021                 if (seq_before(ppp->minseq, PPP_MP_CB(mskb)->sequence))
2022                         ppp->minseq = PPP_MP_CB(mskb)->sequence;
2023         }
2024 
2025         /* Pull completed packets off the queue and receive them. */
2026         while ((skb = ppp_mp_reconstruct(ppp))) {
2027                 if (pskb_may_pull(skb, 2))
2028                         ppp_receive_nonmp_frame(ppp, skb);
2029                 else {
2030                         ++ppp->dev->stats.rx_length_errors;
2031                         kfree_skb(skb);
2032                         ppp_receive_error(ppp);
2033                 }
2034         }
2035 
2036         return;
2037 
2038  err:
2039         kfree_skb(skb);
2040         ppp_receive_error(ppp);
2041 }
2042 
2043 /*
2044  * Insert a fragment on the MP reconstruction queue.
2045  * The queue is ordered by increasing sequence number.
2046  */
2047 static void
2048 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
2049 {
2050         struct sk_buff *p;
2051         struct sk_buff_head *list = &ppp->mrq;
2052         u32 seq = PPP_MP_CB(skb)->sequence;
2053 
2054         /* N.B. we don't need to lock the list lock because we have the
2055            ppp unit receive-side lock. */
2056         skb_queue_walk(list, p) {
2057                 if (seq_before(seq, PPP_MP_CB(p)->sequence))
2058                         break;
2059         }
2060         __skb_queue_before(list, p, skb);
2061 }
2062 
2063 /*
2064  * Reconstruct a packet from the MP fragment queue.
2065  * We go through increasing sequence numbers until we find a
2066  * complete packet, or we get to the sequence number for a fragment
2067  * which hasn't arrived but might still do so.
2068  */
2069 static struct sk_buff *
2070 ppp_mp_reconstruct(struct ppp *ppp)
2071 {
2072         u32 seq = ppp->nextseq;
2073         u32 minseq = ppp->minseq;
2074         struct sk_buff_head *list = &ppp->mrq;
2075         struct sk_buff *p, *tmp;
2076         struct sk_buff *head, *tail;
2077         struct sk_buff *skb = NULL;
2078         int lost = 0, len = 0;
2079 
2080         if (ppp->mrru == 0)     /* do nothing until mrru is set */
2081                 return NULL;
2082         head = list->next;
2083         tail = NULL;
2084         skb_queue_walk_safe(list, p, tmp) {
2085         again:
2086                 if (seq_before(PPP_MP_CB(p)->sequence, seq)) {
2087                         /* this can't happen, anyway ignore the skb */
2088                         netdev_err(ppp->dev, "ppp_mp_reconstruct bad "
2089                                    "seq %u < %u\n",
2090                                    PPP_MP_CB(p)->sequence, seq);
2091                         __skb_unlink(p, list);
2092                         kfree_skb(p);
2093                         continue;
2094                 }
2095                 if (PPP_MP_CB(p)->sequence != seq) {
2096                         u32 oldseq;
2097                         /* Fragment `seq' is missing.  If it is after
2098                            minseq, it might arrive later, so stop here. */
2099                         if (seq_after(seq, minseq))
2100                                 break;
2101                         /* Fragment `seq' is lost, keep going. */
2102                         lost = 1;
2103                         oldseq = seq;
2104                         seq = seq_before(minseq, PPP_MP_CB(p)->sequence)?
2105                                 minseq + 1: PPP_MP_CB(p)->sequence;
2106 
2107                         if (ppp->debug & 1)
2108                                 netdev_printk(KERN_DEBUG, ppp->dev,
2109                                               "lost frag %u..%u\n",
2110                                               oldseq, seq-1);
2111 
2112                         goto again;
2113                 }
2114 
2115                 /*
2116                  * At this point we know that all the fragments from
2117                  * ppp->nextseq to seq are either present or lost.
2118                  * Also, there are no complete packets in the queue
2119                  * that have no missing fragments and end before this
2120                  * fragment.
2121                  */
2122 
2123                 /* B bit set indicates this fragment starts a packet */
2124                 if (PPP_MP_CB(p)->BEbits & B) {
2125                         head = p;
2126                         lost = 0;
2127                         len = 0;
2128                 }
2129 
2130                 len += p->len;
2131 
2132                 /* Got a complete packet yet? */
2133                 if (lost == 0 && (PPP_MP_CB(p)->BEbits & E) &&
2134                     (PPP_MP_CB(head)->BEbits & B)) {
2135                         if (len > ppp->mrru + 2) {
2136                                 ++ppp->dev->stats.rx_length_errors;
2137                                 netdev_printk(KERN_DEBUG, ppp->dev,
2138                                               "PPP: reconstructed packet"
2139                                               " is too long (%d)\n", len);
2140                         } else {
2141                                 tail = p;
2142                                 break;
2143                         }
2144                         ppp->nextseq = seq + 1;
2145                 }
2146 
2147                 /*
2148                  * If this is the ending fragment of a packet,
2149                  * and we haven't found a complete valid packet yet,
2150                  * we can discard up to and including this fragment.
2151                  */
2152                 if (PPP_MP_CB(p)->BEbits & E) {
2153                         struct sk_buff *tmp2;
2154 
2155                         skb_queue_reverse_walk_from_safe(list, p, tmp2) {
2156                                 if (ppp->debug & 1)
2157                                         netdev_printk(KERN_DEBUG, ppp->dev,
2158                                                       "discarding frag %u\n",
2159                                                       PPP_MP_CB(p)->sequence);
2160                                 __skb_unlink(p, list);
2161                                 kfree_skb(p);
2162                         }
2163                         head = skb_peek(list);
2164                         if (!head)
2165                                 break;
2166                 }
2167                 ++seq;
2168         }
2169 
2170         /* If we have a complete packet, copy it all into one skb. */
2171         if (tail != NULL) {
2172                 /* If we have discarded any fragments,
2173                    signal a receive error. */
2174                 if (PPP_MP_CB(head)->sequence != ppp->nextseq) {
2175                         skb_queue_walk_safe(list, p, tmp) {
2176                                 if (p == head)
2177                                         break;
2178                                 if (ppp->debug & 1)
2179                                         netdev_printk(KERN_DEBUG, ppp->dev,
2180                                                       "discarding frag %u\n",
2181                                                       PPP_MP_CB(p)->sequence);
2182                                 __skb_unlink(p, list);
2183                                 kfree_skb(p);
2184                         }
2185 
2186                         if (ppp->debug & 1)
2187                                 netdev_printk(KERN_DEBUG, ppp->dev,
2188                                               "  missed pkts %u..%u\n",
2189                                               ppp->nextseq,
2190                                               PPP_MP_CB(head)->sequence-1);
2191                         ++ppp->dev->stats.rx_dropped;
2192                         ppp_receive_error(ppp);
2193                 }
2194 
2195                 skb = head;
2196                 if (head != tail) {
2197                         struct sk_buff **fragpp = &skb_shinfo(skb)->frag_list;
2198                         p = skb_queue_next(list, head);
2199                         __skb_unlink(skb, list);
2200                         skb_queue_walk_from_safe(list, p, tmp) {
2201                                 __skb_unlink(p, list);
2202                                 *fragpp = p;
2203                                 p->next = NULL;
2204                                 fragpp = &p->next;
2205 
2206                                 skb->len += p->len;
2207                                 skb->data_len += p->len;
2208                                 skb->truesize += p->truesize;
2209 
2210                                 if (p == tail)
2211                                         break;
2212                         }
2213                 } else {
2214                         __skb_unlink(skb, list);
2215                 }
2216 
2217                 ppp->nextseq = PPP_MP_CB(tail)->sequence + 1;
2218         }
2219 
2220         return skb;
2221 }
2222 #endif /* CONFIG_PPP_MULTILINK */
2223 
2224 /*
2225  * Channel interface.
2226  */
2227 
2228 /* Create a new, unattached ppp channel. */
2229 int ppp_register_channel(struct ppp_channel *chan)
2230 {
2231         return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2232 }
2233 
2234 /* Create a new, unattached ppp channel for specified net. */
2235 int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2236 {
2237         struct channel *pch;
2238         struct ppp_net *pn;
2239 
2240         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2241         if (!pch)
2242                 return -ENOMEM;
2243 
2244         pn = ppp_pernet(net);
2245 
2246         pch->ppp = NULL;
2247         pch->chan = chan;
2248         pch->chan_net = net;
2249         chan->ppp = pch;
2250         init_ppp_file(&pch->file, CHANNEL);
2251         pch->file.hdrlen = chan->hdrlen;
2252 #ifdef CONFIG_PPP_MULTILINK
2253         pch->lastseq = -1;
2254 #endif /* CONFIG_PPP_MULTILINK */
2255         init_rwsem(&pch->chan_sem);
2256         spin_lock_init(&pch->downl);
2257         rwlock_init(&pch->upl);
2258 
2259         spin_lock_bh(&pn->all_channels_lock);
2260         pch->file.index = ++pn->last_channel_index;
2261         list_add(&pch->list, &pn->new_channels);
2262         atomic_inc(&channel_count);
2263         spin_unlock_bh(&pn->all_channels_lock);
2264 
2265         return 0;
2266 }
2267 
2268 /*
2269  * Return the index of a channel.
2270  */
2271 int ppp_channel_index(struct ppp_channel *chan)
2272 {
2273         struct channel *pch = chan->ppp;
2274 
2275         if (pch)
2276                 return pch->file.index;
2277         return -1;
2278 }
2279 
2280 /*
2281  * Return the PPP unit number to which a channel is connected.
2282  */
2283 int ppp_unit_number(struct ppp_channel *chan)
2284 {
2285         struct channel *pch = chan->ppp;
2286         int unit = -1;
2287 
2288         if (pch) {
2289                 read_lock_bh(&pch->upl);
2290                 if (pch->ppp)
2291                         unit = pch->ppp->file.index;
2292                 read_unlock_bh(&pch->upl);
2293         }
2294         return unit;
2295 }
2296 
2297 /*
2298  * Return the PPP device interface name of a channel.
2299  */
2300 char *ppp_dev_name(struct ppp_channel *chan)
2301 {
2302         struct channel *pch = chan->ppp;
2303         char *name = NULL;
2304 
2305         if (pch) {
2306                 read_lock_bh(&pch->upl);
2307                 if (pch->ppp && pch->ppp->dev)
2308                         name = pch->ppp->dev->name;
2309                 read_unlock_bh(&pch->upl);
2310         }
2311         return name;
2312 }
2313 
2314 
2315 /*
2316  * Disconnect a channel from the generic layer.
2317  * This must be called in process context.
2318  */
2319 void
2320 ppp_unregister_channel(struct ppp_channel *chan)
2321 {
2322         struct channel *pch = chan->ppp;
2323         struct ppp_net *pn;
2324 
2325         if (!pch)
2326                 return;         /* should never happen */
2327 
2328         chan->ppp = NULL;
2329 
2330         /*
2331          * This ensures that we have returned from any calls into the
2332          * the channel's start_xmit or ioctl routine before we proceed.
2333          */
2334         down_write(&pch->chan_sem);
2335         spin_lock_bh(&pch->downl);
2336         pch->chan = NULL;
2337         spin_unlock_bh(&pch->downl);
2338         up_write(&pch->chan_sem);
2339         ppp_disconnect_channel(pch);
2340 
2341         pn = ppp_pernet(pch->chan_net);
2342         spin_lock_bh(&pn->all_channels_lock);
2343         list_del(&pch->list);
2344         spin_unlock_bh(&pn->all_channels_lock);
2345 
2346         pch->file.dead = 1;
2347         wake_up_interruptible(&pch->file.rwait);
2348         if (atomic_dec_and_test(&pch->file.refcnt))
2349                 ppp_destroy_channel(pch);
2350 }
2351 
2352 /*
2353  * Callback from a channel when it can accept more to transmit.
2354  * This should be called at BH/softirq level, not interrupt level.
2355  */
2356 void
2357 ppp_output_wakeup(struct ppp_channel *chan)
2358 {
2359         struct channel *pch = chan->ppp;
2360 
2361         if (!pch)
2362                 return;
2363         ppp_channel_push(pch);
2364 }
2365 
2366 /*
2367  * Compression control.
2368  */
2369 
2370 /* Process the PPPIOCSCOMPRESS ioctl. */
2371 static int
2372 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2373 {
2374         int err;
2375         struct compressor *cp, *ocomp;
2376         struct ppp_option_data data;
2377         void *state, *ostate;
2378         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2379 
2380         err = -EFAULT;
2381         if (copy_from_user(&data, (void __user *) arg, sizeof(data)) ||
2382             (data.length <= CCP_MAX_OPTION_LENGTH &&
2383              copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2384                 goto out;
2385         err = -EINVAL;
2386         if (data.length > CCP_MAX_OPTION_LENGTH ||
2387             ccp_option[1] < 2 || ccp_option[1] > data.length)
2388                 goto out;
2389 
2390         cp = try_then_request_module(
2391                 find_compressor(ccp_option[0]),
2392                 "ppp-compress-%d", ccp_option[0]);
2393         if (!cp)
2394                 goto out;
2395 
2396         err = -ENOBUFS;
2397         if (data.transmit) {
2398                 state = cp->comp_alloc(ccp_option, data.length);
2399                 if (state) {
2400                         ppp_xmit_lock(ppp);
2401                         ppp->xstate &= ~SC_COMP_RUN;
2402                         ocomp = ppp->xcomp;
2403                         ostate = ppp->xc_state;
2404                         ppp->xcomp = cp;
2405                         ppp->xc_state = state;
2406                         ppp_xmit_unlock(ppp);
2407                         if (ostate) {
2408                                 ocomp->comp_free(ostate);
2409                                 module_put(ocomp->owner);
2410                         }
2411                         err = 0;
2412                 } else
2413                         module_put(cp->owner);
2414 
2415         } else {
2416                 state = cp->decomp_alloc(ccp_option, data.length);
2417                 if (state) {
2418                         ppp_recv_lock(ppp);
2419                         ppp->rstate &= ~SC_DECOMP_RUN;
2420                         ocomp = ppp->rcomp;
2421                         ostate = ppp->rc_state;
2422                         ppp->rcomp = cp;
2423                         ppp->rc_state = state;
2424                         ppp_recv_unlock(ppp);
2425                         if (ostate) {
2426                                 ocomp->decomp_free(ostate);
2427                                 module_put(ocomp->owner);
2428                         }
2429                         err = 0;
2430                 } else
2431                         module_put(cp->owner);
2432         }
2433 
2434  out:
2435         return err;
2436 }
2437 
2438 /*
2439  * Look at a CCP packet and update our state accordingly.
2440  * We assume the caller has the xmit or recv path locked.
2441  */
2442 static void
2443 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2444 {
2445         unsigned char *dp;
2446         int len;
2447 
2448         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2449                 return; /* no header */
2450         dp = skb->data + 2;
2451 
2452         switch (CCP_CODE(dp)) {
2453         case CCP_CONFREQ:
2454 
2455                 /* A ConfReq starts negotiation of compression
2456                  * in one direction of transmission,
2457                  * and hence brings it down...but which way?
2458                  *
2459                  * Remember:
2460                  * A ConfReq indicates what the sender would like to receive
2461                  */
2462                 if(inbound)
2463                         /* He is proposing what I should send */
2464                         ppp->xstate &= ~SC_COMP_RUN;
2465                 else
2466                         /* I am proposing to what he should send */
2467                         ppp->rstate &= ~SC_DECOMP_RUN;
2468 
2469                 break;
2470 
2471         case CCP_TERMREQ:
2472         case CCP_TERMACK:
2473                 /*
2474                  * CCP is going down, both directions of transmission
2475                  */
2476                 ppp->rstate &= ~SC_DECOMP_RUN;
2477                 ppp->xstate &= ~SC_COMP_RUN;
2478                 break;
2479 
2480         case CCP_CONFACK:
2481                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2482                         break;
2483                 len = CCP_LENGTH(dp);
2484                 if (!pskb_may_pull(skb, len + 2))
2485                         return;         /* too short */
2486                 dp += CCP_HDRLEN;
2487                 len -= CCP_HDRLEN;
2488                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2489                         break;
2490                 if (inbound) {
2491                         /* we will start receiving compressed packets */
2492                         if (!ppp->rc_state)
2493                                 break;
2494                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2495                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2496                                 ppp->rstate |= SC_DECOMP_RUN;
2497                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2498                         }
2499                 } else {
2500                         /* we will soon start sending compressed packets */
2501                         if (!ppp->xc_state)
2502                                 break;
2503                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2504                                         ppp->file.index, 0, ppp->debug))
2505                                 ppp->xstate |= SC_COMP_RUN;
2506                 }
2507                 break;
2508 
2509         case CCP_RESETACK:
2510                 /* reset the [de]compressor */
2511                 if ((ppp->flags & SC_CCP_UP) == 0)
2512                         break;
2513                 if (inbound) {
2514                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2515                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2516                                 ppp->rstate &= ~SC_DC_ERROR;
2517                         }
2518                 } else {
2519                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2520                                 ppp->xcomp->comp_reset(ppp->xc_state);
2521                 }
2522                 break;
2523         }
2524 }
2525 
2526 /* Free up compression resources. */
2527 static void
2528 ppp_ccp_closed(struct ppp *ppp)
2529 {
2530         void *xstate, *rstate;
2531         struct compressor *xcomp, *rcomp;
2532 
2533         ppp_lock(ppp);
2534         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2535         ppp->xstate = 0;
2536         xcomp = ppp->xcomp;
2537         xstate = ppp->xc_state;
2538         ppp->xc_state = NULL;
2539         ppp->rstate = 0;
2540         rcomp = ppp->rcomp;
2541         rstate = ppp->rc_state;
2542         ppp->rc_state = NULL;
2543         ppp_unlock(ppp);
2544 
2545         if (xstate) {
2546                 xcomp->comp_free(xstate);
2547                 module_put(xcomp->owner);
2548         }
2549         if (rstate) {
2550                 rcomp->decomp_free(rstate);
2551                 module_put(rcomp->owner);
2552         }
2553 }
2554 
2555 /* List of compressors. */
2556 static LIST_HEAD(compressor_list);
2557 static DEFINE_SPINLOCK(compressor_list_lock);
2558 
2559 struct compressor_entry {
2560         struct list_head list;
2561         struct compressor *comp;
2562 };
2563 
2564 static struct compressor_entry *
2565 find_comp_entry(int proto)
2566 {
2567         struct compressor_entry *ce;
2568 
2569         list_for_each_entry(ce, &compressor_list, list) {
2570                 if (ce->comp->compress_proto == proto)
2571                         return ce;
2572         }
2573         return NULL;
2574 }
2575 
2576 /* Register a compressor */
2577 int
2578 ppp_register_compressor(struct compressor *cp)
2579 {
2580         struct compressor_entry *ce;
2581         int ret;
2582         spin_lock(&compressor_list_lock);
2583         ret = -EEXIST;
2584         if (find_comp_entry(cp->compress_proto))
2585                 goto out;
2586         ret = -ENOMEM;
2587         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2588         if (!ce)
2589                 goto out;
2590         ret = 0;
2591         ce->comp = cp;
2592         list_add(&ce->list, &compressor_list);
2593  out:
2594         spin_unlock(&compressor_list_lock);
2595         return ret;
2596 }
2597 
2598 /* Unregister a compressor */
2599 void
2600 ppp_unregister_compressor(struct compressor *cp)
2601 {
2602         struct compressor_entry *ce;
2603 
2604         spin_lock(&compressor_list_lock);
2605         ce = find_comp_entry(cp->compress_proto);
2606         if (ce && ce->comp == cp) {
2607                 list_del(&ce->list);
2608                 kfree(ce);
2609         }
2610         spin_unlock(&compressor_list_lock);
2611 }
2612 
2613 /* Find a compressor. */
2614 static struct compressor *
2615 find_compressor(int type)
2616 {
2617         struct compressor_entry *ce;
2618         struct compressor *cp = NULL;
2619 
2620         spin_lock(&compressor_list_lock);
2621         ce = find_comp_entry(type);
2622         if (ce) {
2623                 cp = ce->comp;
2624                 if (!try_module_get(cp->owner))
2625                         cp = NULL;
2626         }
2627         spin_unlock(&compressor_list_lock);
2628         return cp;
2629 }
2630 
2631 /*
2632  * Miscelleneous stuff.
2633  */
2634 
2635 static void
2636 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2637 {
2638         struct slcompress *vj = ppp->vj;
2639 
2640         memset(st, 0, sizeof(*st));
2641         st->p.ppp_ipackets = ppp->stats64.rx_packets;
2642         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2643         st->p.ppp_ibytes = ppp->stats64.rx_bytes;
2644         st->p.ppp_opackets = ppp->stats64.tx_packets;
2645         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2646         st->p.ppp_obytes = ppp->stats64.tx_bytes;
2647         if (!vj)
2648                 return;
2649         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2650         st->vj.vjs_compressed = vj->sls_o_compressed;
2651         st->vj.vjs_searches = vj->sls_o_searches;
2652         st->vj.vjs_misses = vj->sls_o_misses;
2653         st->vj.vjs_errorin = vj->sls_i_error;
2654         st->vj.vjs_tossed = vj->sls_i_tossed;
2655         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2656         st->vj.vjs_compressedin = vj->sls_i_compressed;
2657 }
2658 
2659 /*
2660  * Stuff for handling the lists of ppp units and channels
2661  * and for initialization.
2662  */
2663 
2664 /*
2665  * Create a new ppp interface unit.  Fails if it can't allocate memory
2666  * or if there is already a unit with the requested number.
2667  * unit == -1 means allocate a new number.
2668  */
2669 static struct ppp *
2670 ppp_create_interface(struct net *net, int unit, int *retp)
2671 {
2672         struct ppp *ppp;
2673         struct ppp_net *pn;
2674         struct net_device *dev = NULL;
2675         int ret = -ENOMEM;
2676         int i;
2677 
2678         dev = alloc_netdev(sizeof(struct ppp), "", NET_NAME_UNKNOWN,
2679                            ppp_setup);
2680         if (!dev)
2681                 goto out1;
2682 
2683         pn = ppp_pernet(net);
2684 
2685         ppp = netdev_priv(dev);
2686         ppp->dev = dev;
2687         ppp->mru = PPP_MRU;
2688         init_ppp_file(&ppp->file, INTERFACE);
2689         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2690         for (i = 0; i < NUM_NP; ++i)
2691                 ppp->npmode[i] = NPMODE_PASS;
2692         INIT_LIST_HEAD(&ppp->channels);
2693         spin_lock_init(&ppp->rlock);
2694         spin_lock_init(&ppp->wlock);
2695 #ifdef CONFIG_PPP_MULTILINK
2696         ppp->minseq = -1;
2697         skb_queue_head_init(&ppp->mrq);
2698 #endif /* CONFIG_PPP_MULTILINK */
2699 #ifdef CONFIG_PPP_FILTER
2700         ppp->pass_filter = NULL;
2701         ppp->active_filter = NULL;
2702 #endif /* CONFIG_PPP_FILTER */
2703 
2704         /*
2705          * drum roll: don't forget to set
2706          * the net device is belong to
2707          */
2708         dev_net_set(dev, net);
2709 
2710         mutex_lock(&pn->all_ppp_mutex);
2711 
2712         if (unit < 0) {
2713                 unit = unit_get(&pn->units_idr, ppp);
2714                 if (unit < 0) {
2715                         ret = unit;
2716                         goto out2;
2717                 }
2718         } else {
2719                 ret = -EEXIST;
2720                 if (unit_find(&pn->units_idr, unit))
2721                         goto out2; /* unit already exists */
2722                 /*
2723                  * if caller need a specified unit number
2724                  * lets try to satisfy him, otherwise --
2725                  * he should better ask us for new unit number
2726                  *
2727                  * NOTE: yes I know that returning EEXIST it's not
2728                  * fair but at least pppd will ask us to allocate
2729                  * new unit in this case so user is happy :)
2730                  */
2731                 unit = unit_set(&pn->units_idr, ppp, unit);
2732                 if (unit < 0)
2733                         goto out2;
2734         }
2735 
2736         /* Initialize the new ppp unit */
2737         ppp->file.index = unit;
2738         sprintf(dev->name, "ppp%d", unit);
2739 
2740         ret = register_netdev(dev);
2741         if (ret != 0) {
2742                 unit_put(&pn->units_idr, unit);
2743                 netdev_err(ppp->dev, "PPP: couldn't register device %s (%d)\n",
2744                            dev->name, ret);
2745                 goto out2;
2746         }
2747 
2748         ppp->ppp_net = net;
2749 
2750         atomic_inc(&ppp_unit_count);
2751         mutex_unlock(&pn->all_ppp_mutex);
2752 
2753         *retp = 0;
2754         return ppp;
2755 
2756 out2:
2757         mutex_unlock(&pn->all_ppp_mutex);
2758         free_netdev(dev);
2759 out1:
2760         *retp = ret;
2761         return NULL;
2762 }
2763 
2764 /*
2765  * Initialize a ppp_file structure.
2766  */
2767 static void
2768 init_ppp_file(struct ppp_file *pf, int kind)
2769 {
2770         pf->kind = kind;
2771         skb_queue_head_init(&pf->xq);
2772         skb_queue_head_init(&pf->rq);
2773         atomic_set(&pf->refcnt, 1);
2774         init_waitqueue_head(&pf->rwait);
2775 }
2776 
2777 /*
2778  * Take down a ppp interface unit - called when the owning file
2779  * (the one that created the unit) is closed or detached.
2780  */
2781 static void ppp_shutdown_interface(struct ppp *ppp)
2782 {
2783         struct ppp_net *pn;
2784 
2785         pn = ppp_pernet(ppp->ppp_net);
2786         mutex_lock(&pn->all_ppp_mutex);
2787 
2788         /* This will call dev_close() for us. */
2789         ppp_lock(ppp);
2790         if (!ppp->closing) {
2791                 ppp->closing = 1;
2792                 ppp_unlock(ppp);
2793                 unregister_netdev(ppp->dev);
2794                 unit_put(&pn->units_idr, ppp->file.index);
2795         } else
2796                 ppp_unlock(ppp);
2797 
2798         ppp->file.dead = 1;
2799         ppp->owner = NULL;
2800         wake_up_interruptible(&ppp->file.rwait);
2801 
2802         mutex_unlock(&pn->all_ppp_mutex);
2803 }
2804 
2805 /*
2806  * Free the memory used by a ppp unit.  This is only called once
2807  * there are no channels connected to the unit and no file structs
2808  * that reference the unit.
2809  */
2810 static void ppp_destroy_interface(struct ppp *ppp)
2811 {
2812         atomic_dec(&ppp_unit_count);
2813 
2814         if (!ppp->file.dead || ppp->n_channels) {
2815                 /* "can't happen" */
2816                 netdev_err(ppp->dev, "ppp: destroying ppp struct %p "
2817                            "but dead=%d n_channels=%d !\n",
2818                            ppp, ppp->file.dead, ppp->n_channels);
2819                 return;
2820         }
2821 
2822         ppp_ccp_closed(ppp);
2823         if (ppp->vj) {
2824                 slhc_free(ppp->vj);
2825                 ppp->vj = NULL;
2826         }
2827         skb_queue_purge(&ppp->file.xq);
2828         skb_queue_purge(&ppp->file.rq);
2829 #ifdef CONFIG_PPP_MULTILINK
2830         skb_queue_purge(&ppp->mrq);
2831 #endif /* CONFIG_PPP_MULTILINK */
2832 #ifdef CONFIG_PPP_FILTER
2833         if (ppp->pass_filter) {
2834                 bpf_prog_destroy(ppp->pass_filter);
2835                 ppp->pass_filter = NULL;
2836         }
2837 
2838         if (ppp->active_filter) {
2839                 bpf_prog_destroy(ppp->active_filter);
2840                 ppp->active_filter = NULL;
2841         }
2842 #endif /* CONFIG_PPP_FILTER */
2843 
2844         kfree_skb(ppp->xmit_pending);
2845 
2846         free_netdev(ppp->dev);
2847 }
2848 
2849 /*
2850  * Locate an existing ppp unit.
2851  * The caller should have locked the all_ppp_mutex.
2852  */
2853 static struct ppp *
2854 ppp_find_unit(struct ppp_net *pn, int unit)
2855 {
2856         return unit_find(&pn->units_idr, unit);
2857 }
2858 
2859 /*
2860  * Locate an existing ppp channel.
2861  * The caller should have locked the all_channels_lock.
2862  * First we look in the new_channels list, then in the
2863  * all_channels list.  If found in the new_channels list,
2864  * we move it to the all_channels list.  This is for speed
2865  * when we have a lot of channels in use.
2866  */
2867 static struct channel *
2868 ppp_find_channel(struct ppp_net *pn, int unit)
2869 {
2870         struct channel *pch;
2871 
2872         list_for_each_entry(pch, &pn->new_channels, list) {
2873                 if (pch->file.index == unit) {
2874                         list_move(&pch->list, &pn->all_channels);
2875                         return pch;
2876                 }
2877         }
2878 
2879         list_for_each_entry(pch, &pn->all_channels, list) {
2880                 if (pch->file.index == unit)
2881                         return pch;
2882         }
2883 
2884         return NULL;
2885 }
2886 
2887 /*
2888  * Connect a PPP channel to a PPP interface unit.
2889  */
2890 static int
2891 ppp_connect_channel(struct channel *pch, int unit)
2892 {
2893         struct ppp *ppp;
2894         struct ppp_net *pn;
2895         int ret = -ENXIO;
2896         int hdrlen;
2897 
2898         pn = ppp_pernet(pch->chan_net);
2899 
2900         mutex_lock(&pn->all_ppp_mutex);
2901         ppp = ppp_find_unit(pn, unit);
2902         if (!ppp)
2903                 goto out;
2904         write_lock_bh(&pch->upl);
2905         ret = -EINVAL;
2906         if (pch->ppp)
2907                 goto outl;
2908 
2909         ppp_lock(ppp);
2910         if (pch->file.hdrlen > ppp->file.hdrlen)
2911                 ppp->file.hdrlen = pch->file.hdrlen;
2912         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2913         if (hdrlen > ppp->dev->hard_header_len)
2914                 ppp->dev->hard_header_len = hdrlen;
2915         list_add_tail(&pch->clist, &ppp->channels);
2916         ++ppp->n_channels;
2917         pch->ppp = ppp;
2918         atomic_inc(&ppp->file.refcnt);
2919         ppp_unlock(ppp);
2920         ret = 0;
2921 
2922  outl:
2923         write_unlock_bh(&pch->upl);
2924  out:
2925         mutex_unlock(&pn->all_ppp_mutex);
2926         return ret;
2927 }
2928 
2929 /*
2930  * Disconnect a channel from its ppp unit.
2931  */
2932 static int
2933 ppp_disconnect_channel(struct channel *pch)
2934 {
2935         struct ppp *ppp;
2936         int err = -EINVAL;
2937 
2938         write_lock_bh(&pch->upl);
2939         ppp = pch->ppp;
2940         pch->ppp = NULL;
2941         write_unlock_bh(&pch->upl);
2942         if (ppp) {
2943                 /* remove it from the ppp unit's list */
2944                 ppp_lock(ppp);
2945                 list_del(&pch->clist);
2946                 if (--ppp->n_channels == 0)
2947                         wake_up_interruptible(&ppp->file.rwait);
2948                 ppp_unlock(ppp);
2949                 if (atomic_dec_and_test(&ppp->file.refcnt))
2950                         ppp_destroy_interface(ppp);
2951                 err = 0;
2952         }
2953         return err;
2954 }
2955 
2956 /*
2957  * Free up the resources used by a ppp channel.
2958  */
2959 static void ppp_destroy_channel(struct channel *pch)
2960 {
2961         atomic_dec(&channel_count);
2962 
2963         if (!pch->file.dead) {
2964                 /* "can't happen" */
2965                 pr_err("ppp: destroying undead channel %p !\n", pch);
2966                 return;
2967         }
2968         skb_queue_purge(&pch->file.xq);
2969         skb_queue_purge(&pch->file.rq);
2970         kfree(pch);
2971 }
2972 
2973 static void __exit ppp_cleanup(void)
2974 {
2975         /* should never happen */
2976         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2977                 pr_err("PPP: removing module but units remain!\n");
2978         unregister_chrdev(PPP_MAJOR, "ppp");
2979         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2980         class_destroy(ppp_class);
2981         unregister_pernet_device(&ppp_net_ops);
2982 }
2983 
2984 /*
2985  * Units handling. Caller must protect concurrent access
2986  * by holding all_ppp_mutex
2987  */
2988 
2989 /* associate pointer with specified number */
2990 static int unit_set(struct idr *p, void *ptr, int n)
2991 {
2992         int unit;
2993 
2994         unit = idr_alloc(p, ptr, n, n + 1, GFP_KERNEL);
2995         if (unit == -ENOSPC)
2996                 unit = -EINVAL;
2997         return unit;
2998 }
2999 
3000 /* get new free unit number and associate pointer with it */
3001 static int unit_get(struct idr *p, void *ptr)
3002 {
3003         return idr_alloc(p, ptr, 0, 0, GFP_KERNEL);
3004 }
3005 
3006 /* put unit number back to a pool */
3007 static void unit_put(struct idr *p, int n)
3008 {
3009         idr_remove(p, n);
3010 }
3011 
3012 /* get pointer associated with the number */
3013 static void *unit_find(struct idr *p, int n)
3014 {
3015         return idr_find(p, n);
3016 }
3017 
3018 /* Module/initialization stuff */
3019 
3020 module_init(ppp_init);
3021 module_exit(ppp_cleanup);
3022 
3023 EXPORT_SYMBOL(ppp_register_net_channel);
3024 EXPORT_SYMBOL(ppp_register_channel);
3025 EXPORT_SYMBOL(ppp_unregister_channel);
3026 EXPORT_SYMBOL(ppp_channel_index);
3027 EXPORT_SYMBOL(ppp_unit_number);
3028 EXPORT_SYMBOL(ppp_dev_name);
3029 EXPORT_SYMBOL(ppp_input);
3030 EXPORT_SYMBOL(ppp_input_error);
3031 EXPORT_SYMBOL(ppp_output_wakeup);
3032 EXPORT_SYMBOL(ppp_register_compressor);
3033 EXPORT_SYMBOL(ppp_unregister_compressor);
3034 MODULE_LICENSE("GPL");
3035 MODULE_ALIAS_CHARDEV(PPP_MAJOR, 0);
3036 MODULE_ALIAS("devname:ppp");
3037 

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