kernel/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                 skb_checksum_complete_unset(skb);
1720 #ifdef CONFIG_PPP_MULTILINK
1721                 /* XXX do channel-level decompression here */
1722                 if (PPP_PROTO(skb) == PPP_MP)
1723                         ppp_receive_mp_frame(ppp, skb, pch);
1724                 else
1725 #endif /* CONFIG_PPP_MULTILINK */
1726                         ppp_receive_nonmp_frame(ppp, skb);
1727         } else {
1728                 kfree_skb(skb);
1729                 ppp_receive_error(ppp);
1730         }
1731 }
1732
1733 static void
1734 ppp_receive_error(struct ppp *ppp)
1735 {
1736         ++ppp->dev->stats.rx_errors;
1737         if (ppp->vj)
1738                 slhc_toss(ppp->vj);
1739 }
1740
1741 static void
1742 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1743 {
1744         struct sk_buff *ns;
1745         int proto, len, npi;
1746
1747         /*
1748          * Decompress the frame, if compressed.
1749          * Note that some decompressors need to see uncompressed frames
1750          * that come in as well as compressed frames.
1751          */
1752         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN) &&
1753             (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1754                 skb = ppp_decompress_frame(ppp, skb);
1755
1756         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1757                 goto err;
1758
1759         proto = PPP_PROTO(skb);
1760         switch (proto) {
1761         case PPP_VJC_COMP:
1762                 /* decompress VJ compressed packets */
1763                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1764                         goto err;
1765
1766                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1767                         /* copy to a new sk_buff with more tailroom */
1768                         ns = dev_alloc_skb(skb->len + 128);
1769                         if (!ns) {
1770                                 netdev_err(ppp->dev, "PPP: no memory "
1771                                            "(VJ decomp)\n");
1772                                 goto err;
1773                         }
1774                         skb_reserve(ns, 2);
1775                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1776                         consume_skb(skb);
1777                         skb = ns;
1778                 }
1779                 else
1780                         skb->ip_summed = CHECKSUM_NONE;
1781
1782                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1783                 if (len <= 0) {
1784                         netdev_printk(KERN_DEBUG, ppp->dev,
1785                                       "PPP: VJ decompression error\n");
1786                         goto err;
1787                 }
1788                 len += 2;
1789                 if (len > skb->len)
1790                         skb_put(skb, len - skb->len);
1791                 else if (len < skb->len)
1792                         skb_trim(skb, len);
1793                 proto = PPP_IP;
1794                 break;
1795
1796         case PPP_VJC_UNCOMP:
1797                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1798                         goto err;
1799
1800                 /* Until we fix the decompressor need to make sure
1801                  * data portion is linear.
1802                  */
1803                 if (!pskb_may_pull(skb, skb->len))
1804                         goto err;
1805
1806                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1807                         netdev_err(ppp->dev, "PPP: VJ uncompressed error\n");
1808                         goto err;
1809                 }
1810                 proto = PPP_IP;
1811                 break;
1812
1813         case PPP_CCP:
1814                 ppp_ccp_peek(ppp, skb, 1);
1815                 break;
1816         }
1817
1818         ++ppp->stats64.rx_packets;
1819         ppp->stats64.rx_bytes += skb->len - 2;
1820
1821         npi = proto_to_npindex(proto);
1822         if (npi < 0) {
1823                 /* control or unknown frame - pass it to pppd */
1824                 skb_queue_tail(&ppp->file.rq, skb);
1825                 /* limit queue length by dropping old frames */
1826                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN &&
1827                        (skb = skb_dequeue(&ppp->file.rq)))
1828                         kfree_skb(skb);
1829                 /* wake up any process polling or blocking on read */
1830                 wake_up_interruptible(&ppp->file.rwait);
1831
1832         } else {
1833                 /* network protocol frame - give it to the kernel */
1834
1835 #ifdef CONFIG_PPP_FILTER
1836                 /* check if the packet passes the pass and active filters */
1837                 /* the filter instructions are constructed assuming
1838                    a four-byte PPP header on each packet */
1839                 if (ppp->pass_filter || ppp->active_filter) {
1840                         if (skb_unclone(skb, GFP_ATOMIC))
1841                                 goto err;
1842
1843                         *skb_push(skb, 2) = 0;
1844                         if (ppp->pass_filter &&
1845                             BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
1846                                 if (ppp->debug & 1)
1847                                         netdev_printk(KERN_DEBUG, ppp->dev,
1848                                                       "PPP: inbound frame "
1849                                                       "not passed\n");
1850                                 kfree_skb(skb);
1851                                 return;
1852                         }
1853                         if (!(ppp->active_filter &&
1854                               BPF_PROG_RUN(ppp->active_filter, skb) == 0))
1855                                 ppp->last_recv = jiffies;
1856                         __skb_pull(skb, 2);
1857                 } else
1858 #endif /* CONFIG_PPP_FILTER */
1859                         ppp->last_recv = jiffies;
1860
1861                 if ((ppp->dev->flags & IFF_UP) == 0 ||
1862                     ppp->npmode[npi] != NPMODE_PASS) {
1863                         kfree_skb(skb);
1864                 } else {
1865                         /* chop off protocol */
1866                         skb_pull_rcsum(skb, 2);
1867                         skb->dev = ppp->dev;
1868                         skb->protocol = htons(npindex_to_ethertype[npi]);
1869                         skb_reset_mac_header(skb);
1870                         netif_rx(skb);
1871                 }
1872         }
1873         return;
1874
1875  err:
1876         kfree_skb(skb);
1877         ppp_receive_error(ppp);
1878 }
1879
1880 static struct sk_buff *
1881 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1882 {
1883         int proto = PPP_PROTO(skb);
1884         struct sk_buff *ns;
1885         int len;
1886
1887         /* Until we fix all the decompressor's need to make sure
1888          * data portion is linear.
1889          */
1890         if (!pskb_may_pull(skb, skb->len))
1891                 goto err;
1892
1893         if (proto == PPP_COMP) {
1894                 int obuff_size;
1895
1896                 switch(ppp->rcomp->compress_proto) {
1897                 case CI_MPPE:
1898                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1899                         break;
1900                 default:
1901                         obuff_size = ppp->mru + PPP_HDRLEN;
1902                         break;
1903                 }
1904
1905                 ns = dev_alloc_skb(obuff_size);
1906                 if (!ns) {
1907                         netdev_err(ppp->dev, "ppp_decompress_frame: "
1908                                    "no memory\n");
1909                         goto err;
1910                 }
1911                 /* the decompressor still expects the A/C bytes in the hdr */
1912                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1913                                 skb->len + 2, ns->data, obuff_size);
1914                 if (len < 0) {
1915                         /* Pass the compressed frame to pppd as an
1916                            error indication. */
1917                         if (len == DECOMP_FATALERROR)
1918                                 ppp->rstate |= SC_DC_FERROR;
1919                         kfree_skb(ns);
1920                         goto err;
1921                 }
1922
1923                 consume_skb(skb);
1924                 skb = ns;
1925                 skb_put(skb, len);
1926                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1927
1928         } else {
1929                 /* Uncompressed frame - pass to decompressor so it
1930                    can update its dictionary if necessary. */
1931                 if (ppp->rcomp->incomp)
1932                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1933                                            skb->len + 2);
1934         }
1935
1936         return skb;
1937
1938  err:
1939         ppp->rstate |= SC_DC_ERROR;
1940         ppp_receive_error(ppp);
1941         return skb;
1942 }
1943
1944 #ifdef CONFIG_PPP_MULTILINK
1945 /*
1946  * Receive a multilink frame.
1947  * We put it on the reconstruction queue and then pull off
1948  * as many completed frames as we can.
1949  */
1950 static void
1951 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1952 {
1953         u32 mask, seq;
1954         struct channel *ch;
1955         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1956
1957         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1958                 goto err;               /* no good, throw it away */
1959
1960         /* Decode sequence number and begin/end bits */
1961         if (ppp->flags & SC_MP_SHORTSEQ) {
1962                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1963                 mask = 0xfff;
1964         } else {
1965                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1966                 mask = 0xffffff;
1967         }
1968         PPP_MP_CB(skb)->BEbits = skb->data[2];
1969         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1970
1971         /*
1972          * Do protocol ID decompression on the first fragment of each packet.
1973          */
1974         if ((PPP_MP_CB(skb)->BEbits & B) && (skb->data[0] & 1))
1975                 *skb_push(skb, 1) = 0;
1976
1977         /*
1978          * Expand sequence number to 32 bits, making it as close
1979          * as possible to ppp->minseq.
1980          */
1981         seq |= ppp->minseq & ~mask;
1982         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1983                 seq += mask + 1;
1984         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1985                 seq -= mask + 1;        /* should never happen */
1986         PPP_MP_CB(skb)->sequence = seq;
1987         pch->lastseq = seq;
1988
1989         /*
1990          * If this packet comes before the next one we were expecting,
1991          * drop it.
1992          */
1993         if (seq_before(seq, ppp->nextseq)) {
1994                 kfree_skb(skb);
1995                 ++ppp->dev->stats.rx_dropped;
1996                 ppp_receive_error(ppp);
1997                 return;
1998         }
1999
2000         /*
2001          * Reevaluate minseq, the minimum over all channels of the
2002          * last sequence number received on each channel.  Because of
2003          * the increasing sequence number rule, we know that any fragment
2004          * before `minseq' which hasn't arrived is never going to arrive.
2005          * The list of channels can't change because we have the receive
2006          * side of the ppp unit locked.
2007          */
2008         list_for_each_entry(ch, &ppp->channels, clist) {
2009                 if (seq_before(ch->lastseq, seq))
2010                         seq = ch->lastseq;
2011         }
2012         if (seq_before(ppp->minseq, seq))
2013                 ppp->minseq = seq;
2014
2015         /* Put the fragment on the reconstruction queue */
2016         ppp_mp_insert(ppp, skb);
2017
2018         /* If the queue is getting long, don't wait any longer for packets
2019            before the start of the queue. */
2020         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
2021                 struct sk_buff *mskb = skb_peek(&ppp->mrq);
2022                 if (seq_before(ppp->minseq, PPP_MP_CB(mskb)->sequence))
2023                         ppp->minseq = PPP_MP_CB(mskb)->sequence;
2024         }
2025
2026         /* Pull completed packets off the queue and receive them. */
2027         while ((skb = ppp_mp_reconstruct(ppp))) {
2028                 if (pskb_may_pull(skb, 2))
2029                         ppp_receive_nonmp_frame(ppp, skb);
2030                 else {
2031                         ++ppp->dev->stats.rx_length_errors;
2032                         kfree_skb(skb);
2033                         ppp_receive_error(ppp);
2034                 }
2035         }
2036
2037         return;
2038
2039  err:
2040         kfree_skb(skb);
2041         ppp_receive_error(ppp);
2042 }
2043
2044 /*
2045  * Insert a fragment on the MP reconstruction queue.
2046  * The queue is ordered by increasing sequence number.
2047  */
2048 static void
2049 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
2050 {
2051         struct sk_buff *p;
2052         struct sk_buff_head *list = &ppp->mrq;
2053         u32 seq = PPP_MP_CB(skb)->sequence;
2054
2055         /* N.B. we don't need to lock the list lock because we have the
2056            ppp unit receive-side lock. */
2057         skb_queue_walk(list, p) {
2058                 if (seq_before(seq, PPP_MP_CB(p)->sequence))
2059                         break;
2060         }
2061         __skb_queue_before(list, p, skb);
2062 }
2063
2064 /*
2065  * Reconstruct a packet from the MP fragment queue.
2066  * We go through increasing sequence numbers until we find a
2067  * complete packet, or we get to the sequence number for a fragment
2068  * which hasn't arrived but might still do so.
2069  */
2070 static struct sk_buff *
2071 ppp_mp_reconstruct(struct ppp *ppp)
2072 {
2073         u32 seq = ppp->nextseq;
2074         u32 minseq = ppp->minseq;
2075         struct sk_buff_head *list = &ppp->mrq;
2076         struct sk_buff *p, *tmp;
2077         struct sk_buff *head, *tail;
2078         struct sk_buff *skb = NULL;
2079         int lost = 0, len = 0;
2080
2081         if (ppp->mrru == 0)     /* do nothing until mrru is set */
2082                 return NULL;
2083         head = list->next;
2084         tail = NULL;
2085         skb_queue_walk_safe(list, p, tmp) {
2086         again:
2087                 if (seq_before(PPP_MP_CB(p)->sequence, seq)) {
2088                         /* this can't happen, anyway ignore the skb */
2089                         netdev_err(ppp->dev, "ppp_mp_reconstruct bad "
2090                                    "seq %u < %u\n",
2091                                    PPP_MP_CB(p)->sequence, seq);
2092                         __skb_unlink(p, list);
2093                         kfree_skb(p);
2094                         continue;
2095                 }
2096                 if (PPP_MP_CB(p)->sequence != seq) {
2097                         u32 oldseq;
2098                         /* Fragment `seq' is missing.  If it is after
2099                            minseq, it might arrive later, so stop here. */
2100                         if (seq_after(seq, minseq))
2101                                 break;
2102                         /* Fragment `seq' is lost, keep going. */
2103                         lost = 1;
2104                         oldseq = seq;
2105                         seq = seq_before(minseq, PPP_MP_CB(p)->sequence)?
2106                                 minseq + 1: PPP_MP_CB(p)->sequence;
2107
2108                         if (ppp->debug & 1)
2109                                 netdev_printk(KERN_DEBUG, ppp->dev,
2110                                               "lost frag %u..%u\n",
2111                                               oldseq, seq-1);
2112
2113                         goto again;
2114                 }
2115
2116                 /*
2117                  * At this point we know that all the fragments from
2118                  * ppp->nextseq to seq are either present or lost.
2119                  * Also, there are no complete packets in the queue
2120                  * that have no missing fragments and end before this
2121                  * fragment.
2122                  */
2123
2124                 /* B bit set indicates this fragment starts a packet */
2125                 if (PPP_MP_CB(p)->BEbits & B) {
2126                         head = p;
2127                         lost = 0;
2128                         len = 0;
2129                 }
2130
2131                 len += p->len;
2132
2133                 /* Got a complete packet yet? */
2134                 if (lost == 0 && (PPP_MP_CB(p)->BEbits & E) &&
2135                     (PPP_MP_CB(head)->BEbits & B)) {
2136                         if (len > ppp->mrru + 2) {
2137                                 ++ppp->dev->stats.rx_length_errors;
2138                                 netdev_printk(KERN_DEBUG, ppp->dev,
2139                                               "PPP: reconstructed packet"
2140                                               " is too long (%d)\n", len);
2141                         } else {
2142                                 tail = p;
2143                                 break;
2144                         }
2145                         ppp->nextseq = seq + 1;
2146                 }
2147
2148                 /*
2149                  * If this is the ending fragment of a packet,
2150                  * and we haven't found a complete valid packet yet,
2151                  * we can discard up to and including this fragment.
2152                  */
2153                 if (PPP_MP_CB(p)->BEbits & E) {
2154                         struct sk_buff *tmp2;
2155
2156                         skb_queue_reverse_walk_from_safe(list, p, tmp2) {
2157                                 if (ppp->debug & 1)
2158                                         netdev_printk(KERN_DEBUG, ppp->dev,
2159                                                       "discarding frag %u\n",
2160                                                       PPP_MP_CB(p)->sequence);
2161                                 __skb_unlink(p, list);
2162                                 kfree_skb(p);
2163                         }
2164                         head = skb_peek(list);
2165                         if (!head)
2166                                 break;
2167                 }
2168                 ++seq;
2169         }
2170
2171         /* If we have a complete packet, copy it all into one skb. */
2172         if (tail != NULL) {
2173                 /* If we have discarded any fragments,
2174                    signal a receive error. */
2175                 if (PPP_MP_CB(head)->sequence != ppp->nextseq) {
2176                         skb_queue_walk_safe(list, p, tmp) {
2177                                 if (p == head)
2178                                         break;
2179                                 if (ppp->debug & 1)
2180                                         netdev_printk(KERN_DEBUG, ppp->dev,
2181                                                       "discarding frag %u\n",
2182                                                       PPP_MP_CB(p)->sequence);
2183                                 __skb_unlink(p, list);
2184                                 kfree_skb(p);
2185                         }
2186
2187                         if (ppp->debug & 1)
2188                                 netdev_printk(KERN_DEBUG, ppp->dev,
2189                                               "  missed pkts %u..%u\n",
2190                                               ppp->nextseq,
2191                                               PPP_MP_CB(head)->sequence-1);
2192                         ++ppp->dev->stats.rx_dropped;
2193                         ppp_receive_error(ppp);
2194                 }
2195
2196                 skb = head;
2197                 if (head != tail) {
2198                         struct sk_buff **fragpp = &skb_shinfo(skb)->frag_list;
2199                         p = skb_queue_next(list, head);
2200                         __skb_unlink(skb, list);
2201                         skb_queue_walk_from_safe(list, p, tmp) {
2202                                 __skb_unlink(p, list);
2203                                 *fragpp = p;
2204                                 p->next = NULL;
2205                                 fragpp = &p->next;
2206
2207                                 skb->len += p->len;
2208                                 skb->data_len += p->len;
2209                                 skb->truesize += p->truesize;
2210
2211                                 if (p == tail)
2212                                         break;
2213                         }
2214                 } else {
2215                         __skb_unlink(skb, list);
2216                 }
2217
2218                 ppp->nextseq = PPP_MP_CB(tail)->sequence + 1;
2219         }
2220
2221         return skb;
2222 }
2223 #endif /* CONFIG_PPP_MULTILINK */
2224
2225 /*
2226  * Channel interface.
2227  */
2228
2229 /* Create a new, unattached ppp channel. */
2230 int ppp_register_channel(struct ppp_channel *chan)
2231 {
2232         return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2233 }
2234
2235 /* Create a new, unattached ppp channel for specified net. */
2236 int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2237 {
2238         struct channel *pch;
2239         struct ppp_net *pn;
2240
2241         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2242         if (!pch)
2243                 return -ENOMEM;
2244
2245         pn = ppp_pernet(net);
2246
2247         pch->ppp = NULL;
2248         pch->chan = chan;
2249         pch->chan_net = net;
2250         chan->ppp = pch;
2251         init_ppp_file(&pch->file, CHANNEL);
2252         pch->file.hdrlen = chan->hdrlen;
2253 #ifdef CONFIG_PPP_MULTILINK
2254         pch->lastseq = -1;
2255 #endif /* CONFIG_PPP_MULTILINK */
2256         init_rwsem(&pch->chan_sem);
2257         spin_lock_init(&pch->downl);
2258         rwlock_init(&pch->upl);
2259
2260         spin_lock_bh(&pn->all_channels_lock);
2261         pch->file.index = ++pn->last_channel_index;
2262         list_add(&pch->list, &pn->new_channels);
2263         atomic_inc(&channel_count);
2264         spin_unlock_bh(&pn->all_channels_lock);
2265
2266         return 0;
2267 }
2268
2269 /*
2270  * Return the index of a channel.
2271  */
2272 int ppp_channel_index(struct ppp_channel *chan)
2273 {
2274         struct channel *pch = chan->ppp;
2275
2276         if (pch)
2277                 return pch->file.index;
2278         return -1;
2279 }
2280
2281 /*
2282  * Return the PPP unit number to which a channel is connected.
2283  */
2284 int ppp_unit_number(struct ppp_channel *chan)
2285 {
2286         struct channel *pch = chan->ppp;
2287         int unit = -1;
2288
2289         if (pch) {
2290                 read_lock_bh(&pch->upl);
2291                 if (pch->ppp)
2292                         unit = pch->ppp->file.index;
2293                 read_unlock_bh(&pch->upl);
2294         }
2295         return unit;
2296 }
2297
2298 /*
2299  * Return the PPP device interface name of a channel.
2300  */
2301 char *ppp_dev_name(struct ppp_channel *chan)
2302 {
2303         struct channel *pch = chan->ppp;
2304         char *name = NULL;
2305
2306         if (pch) {
2307                 read_lock_bh(&pch->upl);
2308                 if (pch->ppp && pch->ppp->dev)
2309                         name = pch->ppp->dev->name;
2310                 read_unlock_bh(&pch->upl);
2311         }
2312         return name;
2313 }
2314
2315
2316 /*
2317  * Disconnect a channel from the generic layer.
2318  * This must be called in process context.
2319  */
2320 void
2321 ppp_unregister_channel(struct ppp_channel *chan)
2322 {
2323         struct channel *pch = chan->ppp;
2324         struct ppp_net *pn;
2325
2326         if (!pch)
2327                 return;         /* should never happen */
2328
2329         chan->ppp = NULL;
2330
2331         /*
2332          * This ensures that we have returned from any calls into the
2333          * the channel's start_xmit or ioctl routine before we proceed.
2334          */
2335         down_write(&pch->chan_sem);
2336         spin_lock_bh(&pch->downl);
2337         pch->chan = NULL;
2338         spin_unlock_bh(&pch->downl);
2339         up_write(&pch->chan_sem);
2340         ppp_disconnect_channel(pch);
2341
2342         pn = ppp_pernet(pch->chan_net);
2343         spin_lock_bh(&pn->all_channels_lock);
2344         list_del(&pch->list);
2345         spin_unlock_bh(&pn->all_channels_lock);
2346
2347         pch->file.dead = 1;
2348         wake_up_interruptible(&pch->file.rwait);
2349         if (atomic_dec_and_test(&pch->file.refcnt))
2350                 ppp_destroy_channel(pch);
2351 }
2352
2353 /*
2354  * Callback from a channel when it can accept more to transmit.
2355  * This should be called at BH/softirq level, not interrupt level.
2356  */
2357 void
2358 ppp_output_wakeup(struct ppp_channel *chan)
2359 {
2360         struct channel *pch = chan->ppp;
2361
2362         if (!pch)
2363                 return;
2364         ppp_channel_push(pch);
2365 }
2366
2367 /*
2368  * Compression control.
2369  */
2370
2371 /* Process the PPPIOCSCOMPRESS ioctl. */
2372 static int
2373 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2374 {
2375         int err;
2376         struct compressor *cp, *ocomp;
2377         struct ppp_option_data data;
2378         void *state, *ostate;
2379         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2380
2381         err = -EFAULT;
2382         if (copy_from_user(&data, (void __user *) arg, sizeof(data)) ||
2383             (data.length <= CCP_MAX_OPTION_LENGTH &&
2384              copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2385                 goto out;
2386         err = -EINVAL;
2387         if (data.length > CCP_MAX_OPTION_LENGTH ||
2388             ccp_option[1] < 2 || ccp_option[1] > data.length)
2389                 goto out;
2390
2391         cp = try_then_request_module(
2392                 find_compressor(ccp_option[0]),
2393                 "ppp-compress-%d", ccp_option[0]);
2394         if (!cp)
2395                 goto out;
2396
2397         err = -ENOBUFS;
2398         if (data.transmit) {
2399                 state = cp->comp_alloc(ccp_option, data.length);
2400                 if (state) {
2401                         ppp_xmit_lock(ppp);
2402                         ppp->xstate &= ~SC_COMP_RUN;
2403                         ocomp = ppp->xcomp;
2404                         ostate = ppp->xc_state;
2405                         ppp->xcomp = cp;
2406                         ppp->xc_state = state;
2407                         ppp_xmit_unlock(ppp);
2408                         if (ostate) {
2409                                 ocomp->comp_free(ostate);
2410                                 module_put(ocomp->owner);
2411                         }
2412                         err = 0;
2413                 } else
2414                         module_put(cp->owner);
2415
2416         } else {
2417                 state = cp->decomp_alloc(ccp_option, data.length);
2418                 if (state) {
2419                         ppp_recv_lock(ppp);
2420                         ppp->rstate &= ~SC_DECOMP_RUN;
2421                         ocomp = ppp->rcomp;
2422                         ostate = ppp->rc_state;
2423                         ppp->rcomp = cp;
2424                         ppp->rc_state = state;
2425                         ppp_recv_unlock(ppp);
2426                         if (ostate) {
2427                                 ocomp->decomp_free(ostate);
2428                                 module_put(ocomp->owner);
2429                         }
2430                         err = 0;
2431                 } else
2432                         module_put(cp->owner);
2433         }
2434
2435  out:
2436         return err;
2437 }
2438
2439 /*
2440  * Look at a CCP packet and update our state accordingly.
2441  * We assume the caller has the xmit or recv path locked.
2442  */
2443 static void
2444 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2445 {
2446         unsigned char *dp;
2447         int len;
2448
2449         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2450                 return; /* no header */
2451         dp = skb->data + 2;
2452
2453         switch (CCP_CODE(dp)) {
2454         case CCP_CONFREQ:
2455
2456                 /* A ConfReq starts negotiation of compression
2457                  * in one direction of transmission,
2458                  * and hence brings it down...but which way?
2459                  *
2460                  * Remember:
2461                  * A ConfReq indicates what the sender would like to receive
2462                  */
2463                 if(inbound)
2464                         /* He is proposing what I should send */
2465                         ppp->xstate &= ~SC_COMP_RUN;
2466                 else
2467                         /* I am proposing to what he should send */
2468                         ppp->rstate &= ~SC_DECOMP_RUN;
2469
2470                 break;
2471
2472         case CCP_TERMREQ:
2473         case CCP_TERMACK:
2474                 /*
2475                  * CCP is going down, both directions of transmission
2476                  */
2477                 ppp->rstate &= ~SC_DECOMP_RUN;
2478                 ppp->xstate &= ~SC_COMP_RUN;
2479                 break;
2480
2481         case CCP_CONFACK:
2482                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2483                         break;
2484                 len = CCP_LENGTH(dp);
2485                 if (!pskb_may_pull(skb, len + 2))
2486                         return;         /* too short */
2487                 dp += CCP_HDRLEN;
2488                 len -= CCP_HDRLEN;
2489                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2490                         break;
2491                 if (inbound) {
2492                         /* we will start receiving compressed packets */
2493                         if (!ppp->rc_state)
2494                                 break;
2495                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2496                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2497                                 ppp->rstate |= SC_DECOMP_RUN;
2498                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2499                         }
2500                 } else {
2501                         /* we will soon start sending compressed packets */
2502                         if (!ppp->xc_state)
2503                                 break;
2504                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2505                                         ppp->file.index, 0, ppp->debug))
2506                                 ppp->xstate |= SC_COMP_RUN;
2507                 }
2508                 break;
2509
2510         case CCP_RESETACK:
2511                 /* reset the [de]compressor */
2512                 if ((ppp->flags & SC_CCP_UP) == 0)
2513                         break;
2514                 if (inbound) {
2515                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2516                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2517                                 ppp->rstate &= ~SC_DC_ERROR;
2518                         }
2519                 } else {
2520                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2521                                 ppp->xcomp->comp_reset(ppp->xc_state);
2522                 }
2523                 break;
2524         }
2525 }
2526
2527 /* Free up compression resources. */
2528 static void
2529 ppp_ccp_closed(struct ppp *ppp)
2530 {
2531         void *xstate, *rstate;
2532         struct compressor *xcomp, *rcomp;
2533
2534         ppp_lock(ppp);
2535         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2536         ppp->xstate = 0;
2537         xcomp = ppp->xcomp;
2538         xstate = ppp->xc_state;
2539         ppp->xc_state = NULL;
2540         ppp->rstate = 0;
2541         rcomp = ppp->rcomp;
2542         rstate = ppp->rc_state;
2543         ppp->rc_state = NULL;
2544         ppp_unlock(ppp);
2545
2546         if (xstate) {
2547                 xcomp->comp_free(xstate);
2548                 module_put(xcomp->owner);
2549         }
2550         if (rstate) {
2551                 rcomp->decomp_free(rstate);
2552                 module_put(rcomp->owner);
2553         }
2554 }
2555
2556 /* List of compressors. */
2557 static LIST_HEAD(compressor_list);
2558 static DEFINE_SPINLOCK(compressor_list_lock);
2559
2560 struct compressor_entry {
2561         struct list_head list;
2562         struct compressor *comp;
2563 };
2564
2565 static struct compressor_entry *
2566 find_comp_entry(int proto)
2567 {
2568         struct compressor_entry *ce;
2569
2570         list_for_each_entry(ce, &compressor_list, list) {
2571                 if (ce->comp->compress_proto == proto)
2572                         return ce;
2573         }
2574         return NULL;
2575 }
2576
2577 /* Register a compressor */
2578 int
2579 ppp_register_compressor(struct compressor *cp)
2580 {
2581         struct compressor_entry *ce;
2582         int ret;
2583         spin_lock(&compressor_list_lock);
2584         ret = -EEXIST;
2585         if (find_comp_entry(cp->compress_proto))
2586                 goto out;
2587         ret = -ENOMEM;
2588         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2589         if (!ce)
2590                 goto out;
2591         ret = 0;
2592         ce->comp = cp;
2593         list_add(&ce->list, &compressor_list);
2594  out:
2595         spin_unlock(&compressor_list_lock);
2596         return ret;
2597 }
2598
2599 /* Unregister a compressor */
2600 void
2601 ppp_unregister_compressor(struct compressor *cp)
2602 {
2603         struct compressor_entry *ce;
2604
2605         spin_lock(&compressor_list_lock);
2606         ce = find_comp_entry(cp->compress_proto);
2607         if (ce && ce->comp == cp) {
2608                 list_del(&ce->list);
2609                 kfree(ce);
2610         }
2611         spin_unlock(&compressor_list_lock);
2612 }
2613
2614 /* Find a compressor. */
2615 static struct compressor *
2616 find_compressor(int type)
2617 {
2618         struct compressor_entry *ce;
2619         struct compressor *cp = NULL;
2620
2621         spin_lock(&compressor_list_lock);
2622         ce = find_comp_entry(type);
2623         if (ce) {
2624                 cp = ce->comp;
2625                 if (!try_module_get(cp->owner))
2626                         cp = NULL;
2627         }
2628         spin_unlock(&compressor_list_lock);
2629         return cp;
2630 }
2631
2632 /*
2633  * Miscelleneous stuff.
2634  */
2635
2636 static void
2637 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2638 {
2639         struct slcompress *vj = ppp->vj;
2640
2641         memset(st, 0, sizeof(*st));
2642         st->p.ppp_ipackets = ppp->stats64.rx_packets;
2643         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2644         st->p.ppp_ibytes = ppp->stats64.rx_bytes;
2645         st->p.ppp_opackets = ppp->stats64.tx_packets;
2646         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2647         st->p.ppp_obytes = ppp->stats64.tx_bytes;
2648         if (!vj)
2649                 return;
2650         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2651         st->vj.vjs_compressed = vj->sls_o_compressed;
2652         st->vj.vjs_searches = vj->sls_o_searches;
2653         st->vj.vjs_misses = vj->sls_o_misses;
2654         st->vj.vjs_errorin = vj->sls_i_error;
2655         st->vj.vjs_tossed = vj->sls_i_tossed;
2656         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2657         st->vj.vjs_compressedin = vj->sls_i_compressed;
2658 }
2659
2660 /*
2661  * Stuff for handling the lists of ppp units and channels
2662  * and for initialization.
2663  */
2664
2665 /*
2666  * Create a new ppp interface unit.  Fails if it can't allocate memory
2667  * or if there is already a unit with the requested number.
2668  * unit == -1 means allocate a new number.
2669  */
2670 static struct ppp *
2671 ppp_create_interface(struct net *net, int unit, int *retp)
2672 {
2673         struct ppp *ppp;
2674         struct ppp_net *pn;
2675         struct net_device *dev = NULL;
2676         int ret = -ENOMEM;
2677         int i;
2678
2679         dev = alloc_netdev(sizeof(struct ppp), "", NET_NAME_UNKNOWN,
2680                            ppp_setup);
2681         if (!dev)
2682                 goto out1;
2683
2684         pn = ppp_pernet(net);
2685
2686         ppp = netdev_priv(dev);
2687         ppp->dev = dev;
2688         ppp->mru = PPP_MRU;
2689         init_ppp_file(&ppp->file, INTERFACE);
2690         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2691         for (i = 0; i < NUM_NP; ++i)
2692                 ppp->npmode[i] = NPMODE_PASS;
2693         INIT_LIST_HEAD(&ppp->channels);
2694         spin_lock_init(&ppp->rlock);
2695         spin_lock_init(&ppp->wlock);
2696 #ifdef CONFIG_PPP_MULTILINK
2697         ppp->minseq = -1;
2698         skb_queue_head_init(&ppp->mrq);
2699 #endif /* CONFIG_PPP_MULTILINK */
2700 #ifdef CONFIG_PPP_FILTER
2701         ppp->pass_filter = NULL;
2702         ppp->active_filter = NULL;
2703 #endif /* CONFIG_PPP_FILTER */
2704
2705         /*
2706          * drum roll: don't forget to set
2707          * the net device is belong to
2708          */
2709         dev_net_set(dev, net);
2710
2711         mutex_lock(&pn->all_ppp_mutex);
2712
2713         if (unit < 0) {
2714                 unit = unit_get(&pn->units_idr, ppp);
2715                 if (unit < 0) {
2716                         ret = unit;
2717                         goto out2;
2718                 }
2719         } else {
2720                 ret = -EEXIST;
2721                 if (unit_find(&pn->units_idr, unit))
2722                         goto out2; /* unit already exists */
2723                 /*
2724                  * if caller need a specified unit number
2725                  * lets try to satisfy him, otherwise --
2726                  * he should better ask us for new unit number
2727                  *
2728                  * NOTE: yes I know that returning EEXIST it's not
2729                  * fair but at least pppd will ask us to allocate
2730                  * new unit in this case so user is happy :)
2731                  */
2732                 unit = unit_set(&pn->units_idr, ppp, unit);
2733                 if (unit < 0)
2734                         goto out2;
2735         }
2736
2737         /* Initialize the new ppp unit */
2738         ppp->file.index = unit;
2739         sprintf(dev->name, "ppp%d", unit);
2740
2741         ret = register_netdev(dev);
2742         if (ret != 0) {
2743                 unit_put(&pn->units_idr, unit);
2744                 netdev_err(ppp->dev, "PPP: couldn't register device %s (%d)\n",
2745                            dev->name, ret);
2746                 goto out2;
2747         }
2748
2749         ppp->ppp_net = net;
2750
2751         atomic_inc(&ppp_unit_count);
2752         mutex_unlock(&pn->all_ppp_mutex);
2753
2754         *retp = 0;
2755         return ppp;
2756
2757 out2:
2758         mutex_unlock(&pn->all_ppp_mutex);
2759         free_netdev(dev);
2760 out1:
2761         *retp = ret;
2762         return NULL;
2763 }
2764
2765 /*
2766  * Initialize a ppp_file structure.
2767  */
2768 static void
2769 init_ppp_file(struct ppp_file *pf, int kind)
2770 {
2771         pf->kind = kind;
2772         skb_queue_head_init(&pf->xq);
2773         skb_queue_head_init(&pf->rq);
2774         atomic_set(&pf->refcnt, 1);
2775         init_waitqueue_head(&pf->rwait);
2776 }
2777
2778 /*
2779  * Take down a ppp interface unit - called when the owning file
2780  * (the one that created the unit) is closed or detached.
2781  */
2782 static void ppp_shutdown_interface(struct ppp *ppp)
2783 {
2784         struct ppp_net *pn;
2785
2786         pn = ppp_pernet(ppp->ppp_net);
2787         mutex_lock(&pn->all_ppp_mutex);
2788
2789         /* This will call dev_close() for us. */
2790         ppp_lock(ppp);
2791         if (!ppp->closing) {
2792                 ppp->closing = 1;
2793                 ppp_unlock(ppp);
2794                 unregister_netdev(ppp->dev);
2795                 unit_put(&pn->units_idr, ppp->file.index);
2796         } else
2797                 ppp_unlock(ppp);
2798
2799         ppp->file.dead = 1;
2800         ppp->owner = NULL;
2801         wake_up_interruptible(&ppp->file.rwait);
2802
2803         mutex_unlock(&pn->all_ppp_mutex);
2804 }
2805
2806 /*
2807  * Free the memory used by a ppp unit.  This is only called once
2808  * there are no channels connected to the unit and no file structs
2809  * that reference the unit.
2810  */
2811 static void ppp_destroy_interface(struct ppp *ppp)
2812 {
2813         atomic_dec(&ppp_unit_count);
2814
2815         if (!ppp->file.dead || ppp->n_channels) {
2816                 /* "can't happen" */
2817                 netdev_err(ppp->dev, "ppp: destroying ppp struct %p "
2818                            "but dead=%d n_channels=%d !\n",
2819                            ppp, ppp->file.dead, ppp->n_channels);
2820                 return;
2821         }
2822
2823         ppp_ccp_closed(ppp);
2824         if (ppp->vj) {
2825                 slhc_free(ppp->vj);
2826                 ppp->vj = NULL;
2827         }
2828         skb_queue_purge(&ppp->file.xq);
2829         skb_queue_purge(&ppp->file.rq);
2830 #ifdef CONFIG_PPP_MULTILINK
2831         skb_queue_purge(&ppp->mrq);
2832 #endif /* CONFIG_PPP_MULTILINK */
2833 #ifdef CONFIG_PPP_FILTER
2834         if (ppp->pass_filter) {
2835                 bpf_prog_destroy(ppp->pass_filter);
2836                 ppp->pass_filter = NULL;
2837         }
2838
2839         if (ppp->active_filter) {
2840                 bpf_prog_destroy(ppp->active_filter);
2841                 ppp->active_filter = NULL;
2842         }
2843 #endif /* CONFIG_PPP_FILTER */
2844
2845         kfree_skb(ppp->xmit_pending);
2846
2847         free_netdev(ppp->dev);
2848 }
2849
2850 /*
2851  * Locate an existing ppp unit.
2852  * The caller should have locked the all_ppp_mutex.
2853  */
2854 static struct ppp *
2855 ppp_find_unit(struct ppp_net *pn, int unit)
2856 {
2857         return unit_find(&pn->units_idr, unit);
2858 }
2859
2860 /*
2861  * Locate an existing ppp channel.
2862  * The caller should have locked the all_channels_lock.
2863  * First we look in the new_channels list, then in the
2864  * all_channels list.  If found in the new_channels list,
2865  * we move it to the all_channels list.  This is for speed
2866  * when we have a lot of channels in use.
2867  */
2868 static struct channel *
2869 ppp_find_channel(struct ppp_net *pn, int unit)
2870 {
2871         struct channel *pch;
2872
2873         list_for_each_entry(pch, &pn->new_channels, list) {
2874                 if (pch->file.index == unit) {
2875                         list_move(&pch->list, &pn->all_channels);
2876                         return pch;
2877                 }
2878         }
2879
2880         list_for_each_entry(pch, &pn->all_channels, list) {
2881                 if (pch->file.index == unit)
2882                         return pch;
2883         }
2884
2885         return NULL;
2886 }
2887
2888 /*
2889  * Connect a PPP channel to a PPP interface unit.
2890  */
2891 static int
2892 ppp_connect_channel(struct channel *pch, int unit)
2893 {
2894         struct ppp *ppp;
2895         struct ppp_net *pn;
2896         int ret = -ENXIO;
2897         int hdrlen;
2898
2899         pn = ppp_pernet(pch->chan_net);
2900
2901         mutex_lock(&pn->all_ppp_mutex);
2902         ppp = ppp_find_unit(pn, unit);
2903         if (!ppp)
2904                 goto out;
2905         write_lock_bh(&pch->upl);
2906         ret = -EINVAL;
2907         if (pch->ppp)
2908                 goto outl;
2909
2910         ppp_lock(ppp);
2911         if (pch->file.hdrlen > ppp->file.hdrlen)
2912                 ppp->file.hdrlen = pch->file.hdrlen;
2913         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2914         if (hdrlen > ppp->dev->hard_header_len)
2915                 ppp->dev->hard_header_len = hdrlen;
2916         list_add_tail(&pch->clist, &ppp->channels);
2917         ++ppp->n_channels;
2918         pch->ppp = ppp;
2919         atomic_inc(&ppp->file.refcnt);
2920         ppp_unlock(ppp);
2921         ret = 0;
2922
2923  outl:
2924         write_unlock_bh(&pch->upl);
2925  out:
2926         mutex_unlock(&pn->all_ppp_mutex);
2927         return ret;
2928 }
2929
2930 /*
2931  * Disconnect a channel from its ppp unit.
2932  */
2933 static int
2934 ppp_disconnect_channel(struct channel *pch)
2935 {
2936         struct ppp *ppp;
2937         int err = -EINVAL;
2938
2939         write_lock_bh(&pch->upl);
2940         ppp = pch->ppp;
2941         pch->ppp = NULL;
2942         write_unlock_bh(&pch->upl);
2943         if (ppp) {
2944                 /* remove it from the ppp unit's list */
2945                 ppp_lock(ppp);
2946                 list_del(&pch->clist);
2947                 if (--ppp->n_channels == 0)
2948                         wake_up_interruptible(&ppp->file.rwait);
2949                 ppp_unlock(ppp);
2950                 if (atomic_dec_and_test(&ppp->file.refcnt))
2951                         ppp_destroy_interface(ppp);
2952                 err = 0;
2953         }
2954         return err;
2955 }
2956
2957 /*
2958  * Free up the resources used by a ppp channel.
2959  */
2960 static void ppp_destroy_channel(struct channel *pch)
2961 {
2962         atomic_dec(&channel_count);
2963
2964         if (!pch->file.dead) {
2965                 /* "can't happen" */
2966                 pr_err("ppp: destroying undead channel %p !\n", pch);
2967                 return;
2968         }
2969         skb_queue_purge(&pch->file.xq);
2970         skb_queue_purge(&pch->file.rq);
2971         kfree(pch);
2972 }
2973
2974 static void __exit ppp_cleanup(void)
2975 {
2976         /* should never happen */
2977         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2978                 pr_err("PPP: removing module but units remain!\n");
2979         unregister_chrdev(PPP_MAJOR, "ppp");
2980         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2981         class_destroy(ppp_class);
2982         unregister_pernet_device(&ppp_net_ops);
2983 }
2984
2985 /*
2986  * Units handling. Caller must protect concurrent access
2987  * by holding all_ppp_mutex
2988  */
2989
2990 /* associate pointer with specified number */
2991 static int unit_set(struct idr *p, void *ptr, int n)
2992 {
2993         int unit;
2994
2995         unit = idr_alloc(p, ptr, n, n + 1, GFP_KERNEL);
2996         if (unit == -ENOSPC)
2997                 unit = -EINVAL;
2998         return unit;
2999 }
3000
3001 /* get new free unit number and associate pointer with it */
3002 static int unit_get(struct idr *p, void *ptr)
3003 {
3004         return idr_alloc(p, ptr, 0, 0, GFP_KERNEL);
3005 }
3006
3007 /* put unit number back to a pool */
3008 static void unit_put(struct idr *p, int n)
3009 {
3010         idr_remove(p, n);
3011 }
3012
3013 /* get pointer associated with the number */
3014 static void *unit_find(struct idr *p, int n)
3015 {
3016         return idr_find(p, n);
3017 }
3018
3019 /* Module/initialization stuff */
3020
3021 module_init(ppp_init);
3022 module_exit(ppp_cleanup);
3023
3024 EXPORT_SYMBOL(ppp_register_net_channel);
3025 EXPORT_SYMBOL(ppp_register_channel);
3026 EXPORT_SYMBOL(ppp_unregister_channel);
3027 EXPORT_SYMBOL(ppp_channel_index);
3028 EXPORT_SYMBOL(ppp_unit_number);
3029 EXPORT_SYMBOL(ppp_dev_name);
3030 EXPORT_SYMBOL(ppp_input);
3031 EXPORT_SYMBOL(ppp_input_error);
3032 EXPORT_SYMBOL(ppp_output_wakeup);
3033 EXPORT_SYMBOL(ppp_register_compressor);
3034 EXPORT_SYMBOL(ppp_unregister_compressor);
3035 MODULE_LICENSE("GPL");
3036 MODULE_ALIAS_CHARDEV(PPP_MAJOR, 0);
3037 MODULE_ALIAS("devname:ppp");