drivers/net/ppp/ppp_generic.c

   1 /*
   2  * Generic PPP layer for Linux.
   3  *
   4  * Copyright 1999-2002 Paul Mackerras.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  * The generic PPP layer handles the PPP network interfaces, the
  12  * /dev/ppp device, packet and VJ compression, and multilink.
  13  * It talks to PPP `channels' via the interface defined in
  14  * include/linux/ppp_channel.h.  Channels provide the basic means for
  15  * sending and receiving PPP frames on some kind of communications
  16  * channel.
  17  *
  18  * Part of the code in this driver was inspired by the old async-only
  19  * PPP driver, written by Michael Callahan and Al Longyear, and
  20  * subsequently hacked by Paul Mackerras.
  21  *
  22  * ==FILEVERSION 20041108==
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/kernel.h>
  27 #include <linux/kmod.h>
  28 #include <linux/init.h>
  29 #include <linux/list.h>
  30 #include <linux/idr.h>
  31 #include <linux/netdevice.h>
  32 #include <linux/poll.h>
  33 #include <linux/ppp_defs.h>
  34 #include <linux/filter.h>
  35 #include <linux/ppp-ioctl.h>
  36 #include <linux/ppp_channel.h>
  37 #include <linux/ppp-comp.h>
  38 #include <linux/skbuff.h>
  39 #include <linux/rtnetlink.h>
  40 #include <linux/if_arp.h>
  41 #include <linux/ip.h>
  42 #include <linux/tcp.h>
  43 #include <linux/spinlock.h>
  44 #include <linux/rwsem.h>
  45 #include <linux/stddef.h>
  46 #include <linux/device.h>
  47 #include <linux/mutex.h>
  48 #include <linux/slab.h>
  49 #include <asm/unaligned.h>
  50 #include <net/slhc_vj.h>
  51 #include <linux/atomic.h>
  52
  53 #include <linux/nsproxy.h>
  54 #include <net/net_namespace.h>
  55 #include <net/netns/generic.h>
  56
  57 #define PPP_VERSION     "2.4.2"
  58
  59 /*
  60  * Network protocols we support.
  61  */
  62 #define NP_IP   0               /* Internet Protocol V4 */
  63 #define NP_IPV6 1               /* Internet Protocol V6 */
  64 #define NP_IPX  2               /* IPX protocol */
  65 #define NP_AT   3               /* Appletalk protocol */
  66 #define NP_MPLS_UC 4            /* MPLS unicast */
  67 #define NP_MPLS_MC 5            /* MPLS multicast */
  68 #define NUM_NP  6               /* Number of NPs. */
  69
  70 #define MPHDRLEN        6       /* multilink protocol header length */
  71 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
  72
  73 /*
  74  * An instance of /dev/ppp can be associated with either a ppp
  75  * interface unit or a ppp channel.  In both cases, file->private_data
  76  * points to one of these.
  77  */
  78 struct ppp_file {
  79         enum {
  80                 INTERFACE=1, CHANNEL
  81         }               kind;
  82         struct sk_buff_head xq;         /* pppd transmit queue */
  83         struct sk_buff_head rq;         /* receive queue for pppd */
  84         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
  85         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
  86         int             hdrlen;         /* space to leave for headers */
  87         int             index;          /* interface unit / channel number */
  88         int             dead;           /* unit/channel has been shut down */
  89 };
  90
  91 #define PF_TO_X(pf, X)          container_of(pf, X, file)
  92
  93 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
  94 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
  95
  96 /*
  97  * Data structure to hold primary network stats for which
  98  * we want to use 64 bit storage.  Other network stats
  99  * are stored in dev->stats of the ppp strucute.
 100  */
 101 struct ppp_link_stats {
 102         u64 rx_packets;
 103         u64 tx_packets;
 104         u64 rx_bytes;
 105         u64 tx_bytes;
 106 };
 107
 108 /*
 109  * Data structure describing one ppp unit.
 110  * A ppp unit corresponds to a ppp network interface device
 111  * and represents a multilink bundle.
 112  * It can have 0 or more ppp channels connected to it.
 113  */
 114 struct ppp {
 115         struct ppp_file file;           /* stuff for read/write/poll 0 */
 116         struct file     *owner;         /* file that owns this unit 48 */
 117         struct list_head channels;      /* list of attached channels 4c */
 118         int             n_channels;     /* how many channels are attached 54 */
 119         spinlock_t      rlock;          /* lock for receive side 58 */
 120         spinlock_t      wlock;          /* lock for transmit side 5c */
 121         int             mru;            /* max receive unit 60 */
 122         unsigned int    flags;          /* control bits 64 */
 123         unsigned int    xstate;         /* transmit state bits 68 */
 124         unsigned int    rstate;         /* receive state bits 6c */
 125         int             debug;          /* debug flags 70 */
 126         struct slcompress *vj;          /* state for VJ header compression */
 127         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
 128         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
 129         struct compressor *xcomp;       /* transmit packet compressor 8c */
 130         void            *xc_state;      /* its internal state 90 */
 131         struct compressor *rcomp;       /* receive decompressor 94 */
 132         void            *rc_state;      /* its internal state 98 */
 133         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
 134         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
 135         struct net_device *dev;         /* network interface device a4 */
 136         int             closing;        /* is device closing down? a8 */
 137 #ifdef CONFIG_PPP_MULTILINK
 138         int             nxchan;         /* next channel to send something on */
 139         u32             nxseq;          /* next sequence number to send */
 140         int             mrru;           /* MP: max reconst. receive unit */
 141         u32             nextseq;        /* MP: seq no of next packet */
 142         u32             minseq;         /* MP: min of most recent seqnos */
 143         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 144 #endif /* CONFIG_PPP_MULTILINK */
 145 #ifdef CONFIG_PPP_FILTER
 146         struct bpf_prog *pass_filter;   /* filter for packets to pass */
 147         struct bpf_prog *active_filter; /* filter for pkts to reset idle */
 148 #endif /* CONFIG_PPP_FILTER */
 149         struct net      *ppp_net;       /* the net we belong to */
 150         struct ppp_link_stats stats64;  /* 64 bit network stats */
 151 };
 152
 153 /*
 154  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 155  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 156  * SC_MUST_COMP
 157  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 158  * Bits in xstate: SC_COMP_RUN
 159  */
 160 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 161                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 162                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 163
 164 /*
 165  * Private data structure for each channel.
 166  * This includes the data structure used for multilink.
 167  */
 168 struct channel {
 169         struct ppp_file file;           /* stuff for read/write/poll */
 170         struct list_head list;          /* link in all/new_channels list */
 171         struct ppp_channel *chan;       /* public channel data structure */
 172         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 173         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 174         struct ppp      *ppp;           /* ppp unit we're connected to */
 175         struct net      *chan_net;      /* the net channel belongs to */
 176         struct list_head clist;         /* link in list of channels per unit */
 177         rwlock_t        upl;            /* protects `ppp' */
 178 #ifdef CONFIG_PPP_MULTILINK
 179         u8              avail;          /* flag used in multilink stuff */
 180         u8              had_frag;       /* >= 1 fragments have been sent */
 181         u32             lastseq;        /* MP: last sequence # received */
 182         int             speed;          /* speed of the corresponding ppp channel*/
 183 #endif /* CONFIG_PPP_MULTILINK */
 184 };
 185
 186 /*
 187  * SMP locking issues:
 188  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 189  * list and the ppp.n_channels field, you need to take both locks
 190  * before you modify them.
 191  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 192  * channel.downl.
 193  */
 194
 195 static DEFINE_MUTEX(ppp_mutex);
 196 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 197 static atomic_t channel_count = ATOMIC_INIT(0);
 198
 199 /* per-net private data for this module */
 200 static int ppp_net_id __read_mostly;
 201 struct ppp_net {
 202         /* units to ppp mapping */
 203         struct idr units_idr;
 204
 205         /*
 206          * all_ppp_mutex protects the units_idr mapping.
 207          * It also ensures that finding a ppp unit in the units_idr
 208          * map and updating its file.refcnt field is atomic.
 209          */
 210         struct mutex all_ppp_mutex;
 211
 212         /* channels */
 213         struct list_head all_channels;
 214         struct list_head new_channels;
 215         int last_channel_index;
 216
 217         /*
 218          * all_channels_lock protects all_channels and
 219          * last_channel_index, and the atomicity of find
 220          * a channel and updating its file.refcnt field.
 221          */
 222         spinlock_t all_channels_lock;
 223 };
 224
 225 /* Get the PPP protocol number from a skb */
 226 #define PPP_PROTO(skb)  get_unaligned_be16((skb)->data)
 227
 228 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 229 #define PPP_MAX_RQLEN   32
 230
 231 /*
 232  * Maximum number of multilink fragments queued up.
 233  * This has to be large enough to cope with the maximum latency of
 234  * the slowest channel relative to the others.  Strictly it should
 235  * depend on the number of channels and their characteristics.
 236  */
 237 #define PPP_MP_MAX_QLEN 128
 238
 239 /* Multilink header bits. */
 240 #define B       0x80            /* this fragment begins a packet */
 241 #define E       0x40            /* this fragment ends a packet */
 242
 243 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 244 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 245 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 246
 247 /* Prototypes. */
 248 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
 249                         struct file *file, unsigned int cmd, unsigned long arg);
 250 static void ppp_xmit_process(struct ppp *ppp);
 251 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 252 static void ppp_push(struct ppp *ppp);
 253 static void ppp_channel_push(struct channel *pch);
 254 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 255                               struct channel *pch);
 256 static void ppp_receive_error(struct ppp *ppp);
 257 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 258 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 259                                             struct sk_buff *skb);
 260 #ifdef CONFIG_PPP_MULTILINK
 261 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 262                                 struct channel *pch);
 263 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 264 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 265 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 266 #endif /* CONFIG_PPP_MULTILINK */
 267 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 268 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 269 static void ppp_ccp_closed(struct ppp *ppp);
 270 static struct compressor *find_compressor(int type);
 271 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 272 static struct ppp *ppp_create_interface(struct net *net, int unit,
 273                                         struct file *file, int *retp);
 274 static void init_ppp_file(struct ppp_file *pf, int kind);
 275 static void ppp_destroy_interface(struct ppp *ppp);
 276 static struct ppp *ppp_find_unit(struct ppp_net *pn, int unit);
 277 static struct channel *ppp_find_channel(struct ppp_net *pn, int unit);
 278 static int ppp_connect_channel(struct channel *pch, int unit);
 279 static int ppp_disconnect_channel(struct channel *pch);
 280 static void ppp_destroy_channel(struct channel *pch);
 281 static int unit_get(struct idr *p, void *ptr);
 282 static int unit_set(struct idr *p, void *ptr, int n);
 283 static void unit_put(struct idr *p, int n);
 284 static void *unit_find(struct idr *p, int n);
 285
 286 static 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                         rtnl_lock();
 396                         if (file == ppp->owner)
 397                                 unregister_netdevice(ppp->dev);
 398                         rtnl_unlock();
 399                 }
 400                 if (atomic_dec_and_test(&pf->refcnt)) {
 401                         switch (pf->kind) {
 402                         case INTERFACE:
 403                                 ppp_destroy_interface(PF_TO_PPP(pf));
 404                                 break;
 405                         case CHANNEL:
 406                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 407                                 break;
 408                         }
 409                 }
 410         }
 411         return 0;
 412 }
 413
 414 static ssize_t ppp_read(struct file *file, char __user *buf,
 415                         size_t count, loff_t *ppos)
 416 {
 417         struct ppp_file *pf = file->private_data;
 418         DECLARE_WAITQUEUE(wait, current);
 419         ssize_t ret;
 420         struct sk_buff *skb = NULL;
 421         struct iovec iov;
 422         struct iov_iter to;
 423
 424         ret = count;
 425
 426         if (!pf)
 427                 return -ENXIO;
 428         add_wait_queue(&pf->rwait, &wait);
 429         for (;;) {
 430                 set_current_state(TASK_INTERRUPTIBLE);
 431                 skb = skb_dequeue(&pf->rq);
 432                 if (skb)
 433                         break;
 434                 ret = 0;
 435                 if (pf->dead)
 436                         break;
 437                 if (pf->kind == INTERFACE) {
 438                         /*
 439                          * Return 0 (EOF) on an interface that has no
 440                          * channels connected, unless it is looping
 441                          * network traffic (demand mode).
 442                          */
 443                         struct ppp *ppp = PF_TO_PPP(pf);
 444                         if (ppp->n_channels == 0 &&
 445                             (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 446                                 break;
 447                 }
 448                 ret = -EAGAIN;
 449                 if (file->f_flags & O_NONBLOCK)
 450                         break;
 451                 ret = -ERESTARTSYS;
 452                 if (signal_pending(current))
 453                         break;
 454                 schedule();
 455         }
 456         set_current_state(TASK_RUNNING);
 457         remove_wait_queue(&pf->rwait, &wait);
 458
 459         if (!skb)
 460                 goto out;
 461
 462         ret = -EOVERFLOW;
 463         if (skb->len > count)
 464                 goto outf;
 465         ret = -EFAULT;
 466         iov.iov_base = buf;
 467         iov.iov_len = count;
 468         iov_iter_init(&to, READ, &iov, 1, count);
 469         if (skb_copy_datagram_iter(skb, 0, &to, skb->len))
 470                 goto outf;
 471         ret = skb->len;
 472
 473  outf:
 474         kfree_skb(skb);
 475  out:
 476         return ret;
 477 }
 478
 479 static ssize_t ppp_write(struct file *file, const char __user *buf,
 480                          size_t count, loff_t *ppos)
 481 {
 482         struct ppp_file *pf = file->private_data;
 483         struct sk_buff *skb;
 484         ssize_t ret;
 485
 486         if (!pf)
 487                 return -ENXIO;
 488         ret = -ENOMEM;
 489         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 490         if (!skb)
 491                 goto out;
 492         skb_reserve(skb, pf->hdrlen);
 493         ret = -EFAULT;
 494         if (copy_from_user(skb_put(skb, count), buf, count)) {
 495                 kfree_skb(skb);
 496                 goto out;
 497         }
 498
 499         skb_queue_tail(&pf->xq, skb);
 500
 501         switch (pf->kind) {
 502         case INTERFACE:
 503                 ppp_xmit_process(PF_TO_PPP(pf));
 504                 break;
 505         case CHANNEL:
 506                 ppp_channel_push(PF_TO_CHANNEL(pf));
 507                 break;
 508         }
 509
 510         ret = count;
 511
 512  out:
 513         return ret;
 514 }
 515
 516 /* No kernel lock - fine */
 517 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 518 {
 519         struct ppp_file *pf = file->private_data;
 520         unsigned int mask;
 521
 522         if (!pf)
 523                 return 0;
 524         poll_wait(file, &pf->rwait, wait);
 525         mask = POLLOUT | POLLWRNORM;
 526         if (skb_peek(&pf->rq))
 527                 mask |= POLLIN | POLLRDNORM;
 528         if (pf->dead)
 529                 mask |= POLLHUP;
 530         else if (pf->kind == INTERFACE) {
 531                 /* see comment in ppp_read */
 532                 struct ppp *ppp = PF_TO_PPP(pf);
 533                 if (ppp->n_channels == 0 &&
 534                     (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 535                         mask |= POLLIN | POLLRDNORM;
 536         }
 537
 538         return mask;
 539 }
 540
 541 #ifdef CONFIG_PPP_FILTER
 542 static int get_filter(void __user *arg, struct sock_filter **p)
 543 {
 544         struct sock_fprog uprog;
 545         struct sock_filter *code = NULL;
 546         int len;
 547
 548         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 549                 return -EFAULT;
 550
 551         if (!uprog.len) {
 552                 *p = NULL;
 553                 return 0;
 554         }
 555
 556         len = uprog.len * sizeof(struct sock_filter);
 557         code = memdup_user(uprog.filter, len);
 558         if (IS_ERR(code))
 559                 return PTR_ERR(code);
 560
 561         *p = code;
 562         return uprog.len;
 563 }
 564 #endif /* CONFIG_PPP_FILTER */
 565
 566 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 567 {
 568         struct ppp_file *pf = file->private_data;
 569         struct ppp *ppp;
 570         int err = -EFAULT, val, val2, i;
 571         struct ppp_idle idle;
 572         struct npioctl npi;
 573         int unit, cflags;
 574         struct slcompress *vj;
 575         void __user *argp = (void __user *)arg;
 576         int __user *p = argp;
 577
 578         if (!pf)
 579                 return ppp_unattached_ioctl(current->nsproxy->net_ns,
 580                                         pf, file, cmd, arg);
 581
 582         if (cmd == PPPIOCDETACH) {
 583                 /*
 584                  * We have to be careful here... if the file descriptor
 585                  * has been dup'd, we could have another process in the
 586                  * middle of a poll using the same file *, so we had
 587                  * better not free the interface data structures -
 588                  * instead we fail the ioctl.  Even in this case, we
 589                  * shut down the interface if we are the owner of it.
 590                  * Actually, we should get rid of PPPIOCDETACH, userland
 591                  * (i.e. pppd) could achieve the same effect by closing
 592                  * this fd and reopening /dev/ppp.
 593                  */
 594                 err = -EINVAL;
 595                 mutex_lock(&ppp_mutex);
 596                 if (pf->kind == INTERFACE) {
 597                         ppp = PF_TO_PPP(pf);
 598                         rtnl_lock();
 599                         if (file == ppp->owner)
 600                                 unregister_netdevice(ppp->dev);
 601                         rtnl_unlock();
 602                 }
 603                 if (atomic_long_read(&file->f_count) < 2) {
 604                         ppp_release(NULL, file);
 605                         err = 0;
 606                 } else
 607                         pr_warn("PPPIOCDETACH file->f_count=%ld\n",
 608                                 atomic_long_read(&file->f_count));
 609                 mutex_unlock(&ppp_mutex);
 610                 return err;
 611         }
 612
 613         if (pf->kind == CHANNEL) {
 614                 struct channel *pch;
 615                 struct ppp_channel *chan;
 616
 617                 mutex_lock(&ppp_mutex);
 618                 pch = PF_TO_CHANNEL(pf);
 619
 620                 switch (cmd) {
 621                 case PPPIOCCONNECT:
 622                         if (get_user(unit, p))
 623                                 break;
 624                         err = ppp_connect_channel(pch, unit);
 625                         break;
 626
 627                 case PPPIOCDISCONN:
 628                         err = ppp_disconnect_channel(pch);
 629                         break;
 630
 631                 default:
 632                         down_read(&pch->chan_sem);
 633                         chan = pch->chan;
 634                         err = -ENOTTY;
 635                         if (chan && chan->ops->ioctl)
 636                                 err = chan->ops->ioctl(chan, cmd, arg);
 637                         up_read(&pch->chan_sem);
 638                 }
 639                 mutex_unlock(&ppp_mutex);
 640                 return err;
 641         }
 642
 643         if (pf->kind != INTERFACE) {
 644                 /* can't happen */
 645                 pr_err("PPP: not interface or channel??\n");
 646                 return -EINVAL;
 647         }
 648
 649         mutex_lock(&ppp_mutex);
 650         ppp = PF_TO_PPP(pf);
 651         switch (cmd) {
 652         case PPPIOCSMRU:
 653                 if (get_user(val, p))
 654                         break;
 655                 ppp->mru = val;
 656                 err = 0;
 657                 break;
 658
 659         case PPPIOCSFLAGS:
 660                 if (get_user(val, p))
 661                         break;
 662                 ppp_lock(ppp);
 663                 cflags = ppp->flags & ~val;
 664 #ifdef CONFIG_PPP_MULTILINK
 665                 if (!(ppp->flags & SC_MULTILINK) && (val & SC_MULTILINK))
 666                         ppp->nextseq = 0;
 667 #endif
 668                 ppp->flags = val & SC_FLAG_BITS;
 669                 ppp_unlock(ppp);
 670                 if (cflags & SC_CCP_OPEN)
 671                         ppp_ccp_closed(ppp);
 672                 err = 0;
 673                 break;
 674
 675         case PPPIOCGFLAGS:
 676                 val = ppp->flags | ppp->xstate | ppp->rstate;
 677                 if (put_user(val, p))
 678                         break;
 679                 err = 0;
 680                 break;
 681
 682         case PPPIOCSCOMPRESS:
 683                 err = ppp_set_compress(ppp, arg);
 684                 break;
 685
 686         case PPPIOCGUNIT:
 687                 if (put_user(ppp->file.index, p))
 688                         break;
 689                 err = 0;
 690                 break;
 691
 692         case PPPIOCSDEBUG:
 693                 if (get_user(val, p))
 694                         break;
 695                 ppp->debug = val;
 696                 err = 0;
 697                 break;
 698
 699         case PPPIOCGDEBUG:
 700                 if (put_user(ppp->debug, p))
 701                         break;
 702                 err = 0;
 703                 break;
 704
 705         case PPPIOCGIDLE:
 706                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 707                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 708                 if (copy_to_user(argp, &idle, sizeof(idle)))
 709                         break;
 710                 err = 0;
 711                 break;
 712
 713         case PPPIOCSMAXCID:
 714                 if (get_user(val, p))
 715                         break;
 716                 val2 = 15;
 717                 if ((val >> 16) != 0) {
 718                         val2 = val >> 16;
 719                         val &= 0xffff;
 720                 }
 721                 vj = slhc_init(val2+1, val+1);
 722                 if (!vj) {
 723                         netdev_err(ppp->dev,
 724                                    "PPP: no memory (VJ compressor)\n");
 725                         err = -ENOMEM;
 726                         break;
 727                 }
 728                 ppp_lock(ppp);
 729                 if (ppp->vj)
 730                         slhc_free(ppp->vj);
 731                 ppp->vj = vj;
 732                 ppp_unlock(ppp);
 733                 err = 0;
 734                 break;
 735
 736         case PPPIOCGNPMODE:
 737         case PPPIOCSNPMODE:
 738                 if (copy_from_user(&npi, argp, sizeof(npi)))
 739                         break;
 740                 err = proto_to_npindex(npi.protocol);
 741                 if (err < 0)
 742                         break;
 743                 i = err;
 744                 if (cmd == PPPIOCGNPMODE) {
 745                         err = -EFAULT;
 746                         npi.mode = ppp->npmode[i];
 747                         if (copy_to_user(argp, &npi, sizeof(npi)))
 748                                 break;
 749                 } else {
 750                         ppp->npmode[i] = npi.mode;
 751                         /* we may be able to transmit more packets now (??) */
 752                         netif_wake_queue(ppp->dev);
 753                 }
 754                 err = 0;
 755                 break;
 756
 757 #ifdef CONFIG_PPP_FILTER
 758         case PPPIOCSPASS:
 759         {
 760                 struct sock_filter *code;
 761
 762                 err = get_filter(argp, &code);
 763                 if (err >= 0) {
 764                         struct bpf_prog *pass_filter = NULL;
 765                         struct sock_fprog_kern fprog = {
 766                                 .len = err,
 767                                 .filter = code,
 768                         };
 769
 770                         err = 0;
 771                         if (fprog.filter)
 772                                 err = bpf_prog_create(&pass_filter, &fprog);
 773                         if (!err) {
 774                                 ppp_lock(ppp);
 775                                 if (ppp->pass_filter)
 776                                         bpf_prog_destroy(ppp->pass_filter);
 777                                 ppp->pass_filter = pass_filter;
 778                                 ppp_unlock(ppp);
 779                         }
 780                         kfree(code);
 781                 }
 782                 break;
 783         }
 784         case PPPIOCSACTIVE:
 785         {
 786                 struct sock_filter *code;
 787
 788                 err = get_filter(argp, &code);
 789                 if (err >= 0) {
 790                         struct bpf_prog *active_filter = NULL;
 791                         struct sock_fprog_kern fprog = {
 792                                 .len = err,
 793                                 .filter = code,
 794                         };
 795
 796                         err = 0;
 797                         if (fprog.filter)
 798                                 err = bpf_prog_create(&active_filter, &fprog);
 799                         if (!err) {
 800                                 ppp_lock(ppp);
 801                                 if (ppp->active_filter)
 802                                         bpf_prog_destroy(ppp->active_filter);
 803                                 ppp->active_filter = active_filter;
 804                                 ppp_unlock(ppp);
 805                         }
 806                         kfree(code);
 807                 }
 808                 break;
 809         }
 810 #endif /* CONFIG_PPP_FILTER */
 811
 812 #ifdef CONFIG_PPP_MULTILINK
 813         case PPPIOCSMRRU:
 814                 if (get_user(val, p))
 815                         break;
 816                 ppp_recv_lock(ppp);
 817                 ppp->mrru = val;
 818                 ppp_recv_unlock(ppp);
 819                 err = 0;
 820                 break;
 821 #endif /* CONFIG_PPP_MULTILINK */
 822
 823         default:
 824                 err = -ENOTTY;
 825         }
 826         mutex_unlock(&ppp_mutex);
 827         return err;
 828 }
 829
 830 static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
 831                         struct file *file, unsigned int cmd, unsigned long arg)
 832 {
 833         int unit, err = -EFAULT;
 834         struct ppp *ppp;
 835         struct channel *chan;
 836         struct ppp_net *pn;
 837         int __user *p = (int __user *)arg;
 838
 839         mutex_lock(&ppp_mutex);
 840         switch (cmd) {
 841         case PPPIOCNEWUNIT:
 842                 /* Create a new ppp unit */
 843                 if (get_user(unit, p))
 844                         break;
 845                 ppp = ppp_create_interface(net, unit, file, &err);
 846                 if (!ppp)
 847                         break;
 848                 file->private_data = &ppp->file;
 849                 err = -EFAULT;
 850                 if (put_user(ppp->file.index, p))
 851                         break;
 852                 err = 0;
 853                 break;
 854
 855         case PPPIOCATTACH:
 856                 /* Attach to an existing ppp unit */
 857                 if (get_user(unit, p))
 858                         break;
 859                 err = -ENXIO;
 860                 pn = ppp_pernet(net);
 861                 mutex_lock(&pn->all_ppp_mutex);
 862                 ppp = ppp_find_unit(pn, unit);
 863                 if (ppp) {
 864                         atomic_inc(&ppp->file.refcnt);
 865                         file->private_data = &ppp->file;
 866                         err = 0;
 867                 }
 868                 mutex_unlock(&pn->all_ppp_mutex);
 869                 break;
 870
 871         case PPPIOCATTCHAN:
 872                 if (get_user(unit, p))
 873                         break;
 874                 err = -ENXIO;
 875                 pn = ppp_pernet(net);
 876                 spin_lock_bh(&pn->all_channels_lock);
 877                 chan = ppp_find_channel(pn, unit);
 878                 if (chan) {
 879                         atomic_inc(&chan->file.refcnt);
 880                         file->private_data = &chan->file;
 881                         err = 0;
 882                 }
 883                 spin_unlock_bh(&pn->all_channels_lock);
 884                 break;
 885
 886         default:
 887                 err = -ENOTTY;
 888         }
 889         mutex_unlock(&ppp_mutex);
 890         return err;
 891 }
 892
 893 static const struct file_operations ppp_device_fops = {
 894         .owner          = THIS_MODULE,
 895         .read           = ppp_read,
 896         .write          = ppp_write,
 897         .poll           = ppp_poll,
 898         .unlocked_ioctl = ppp_ioctl,
 899         .open           = ppp_open,
 900         .release        = ppp_release,
 901         .llseek         = noop_llseek,
 902 };
 903
 904 static __net_init int ppp_init_net(struct net *net)
 905 {
 906         struct ppp_net *pn = net_generic(net, ppp_net_id);
 907
 908         idr_init(&pn->units_idr);
 909         mutex_init(&pn->all_ppp_mutex);
 910
 911         INIT_LIST_HEAD(&pn->all_channels);
 912         INIT_LIST_HEAD(&pn->new_channels);
 913
 914         spin_lock_init(&pn->all_channels_lock);
 915
 916         return 0;
 917 }
 918
 919 static __net_exit void ppp_exit_net(struct net *net)
 920 {
 921         struct ppp_net *pn = net_generic(net, ppp_net_id);
 922         struct ppp *ppp;
 923         LIST_HEAD(list);
 924         int id;
 925
 926         rtnl_lock();
 927         idr_for_each_entry(&pn->units_idr, ppp, id)
 928                 unregister_netdevice_queue(ppp->dev, &list);
 929
 930         unregister_netdevice_many(&list);
 931         rtnl_unlock();
 932
 933         idr_destroy(&pn->units_idr);
 934 }
 935
 936 static struct pernet_operations ppp_net_ops = {
 937         .init = ppp_init_net,
 938         .exit = ppp_exit_net,
 939         .id   = &ppp_net_id,
 940         .size = sizeof(struct ppp_net),
 941 };
 942
 943 #define PPP_MAJOR       108
 944
 945 /* Called at boot time if ppp is compiled into the kernel,
 946    or at module load time (from init_module) if compiled as a module. */
 947 static int __init ppp_init(void)
 948 {
 949         int err;
 950
 951         pr_info("PPP generic driver version " PPP_VERSION "\n");
 952
 953         err = register_pernet_device(&ppp_net_ops);
 954         if (err) {
 955                 pr_err("failed to register PPP pernet device (%d)\n", err);
 956                 goto out;
 957         }
 958
 959         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 960         if (err) {
 961                 pr_err("failed to register PPP device (%d)\n", err);
 962                 goto out_net;
 963         }
 964
 965         ppp_class = class_create(THIS_MODULE, "ppp");
 966         if (IS_ERR(ppp_class)) {
 967                 err = PTR_ERR(ppp_class);
 968                 goto out_chrdev;
 969         }
 970
 971         /* not a big deal if we fail here :-) */
 972         device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
 973
 974         return 0;
 975
 976 out_chrdev:
 977         unregister_chrdev(PPP_MAJOR, "ppp");
 978 out_net:
 979         unregister_pernet_device(&ppp_net_ops);
 980 out:
 981         return err;
 982 }
 983
 984 /*
 985  * Network interface unit routines.
 986  */
 987 static netdev_tx_t
 988 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 989 {
 990         struct ppp *ppp = netdev_priv(dev);
 991         int npi, proto;
 992         unsigned char *pp;
 993
 994         npi = ethertype_to_npindex(ntohs(skb->protocol));
 995         if (npi < 0)
 996                 goto outf;
 997
 998         /* Drop, accept or reject the packet */
 999         switch (ppp->npmode[npi]) {
1000         case NPMODE_PASS:
1001                 break;
1002         case NPMODE_QUEUE:
1003                 /* it would be nice to have a way to tell the network
1004                    system to queue this one up for later. */
1005                 goto outf;
1006         case NPMODE_DROP:
1007         case NPMODE_ERROR:
1008                 goto outf;
1009         }
1010
1011         /* Put the 2-byte PPP protocol number on the front,
1012            making sure there is room for the address and control fields. */
1013         if (skb_cow_head(skb, PPP_HDRLEN))
1014                 goto outf;
1015
1016         pp = skb_push(skb, 2);
1017         proto = npindex_to_proto[npi];
1018         put_unaligned_be16(proto, pp);
1019
1020         skb_queue_tail(&ppp->file.xq, skb);
1021         ppp_xmit_process(ppp);
1022         return NETDEV_TX_OK;
1023
1024  outf:
1025         kfree_skb(skb);
1026         ++dev->stats.tx_dropped;
1027         return NETDEV_TX_OK;
1028 }
1029
1030 static int
1031 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
1032 {
1033         struct ppp *ppp = netdev_priv(dev);
1034         int err = -EFAULT;
1035         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
1036         struct ppp_stats stats;
1037         struct ppp_comp_stats cstats;
1038         char *vers;
1039
1040         switch (cmd) {
1041         case SIOCGPPPSTATS:
1042                 ppp_get_stats(ppp, &stats);
1043                 if (copy_to_user(addr, &stats, sizeof(stats)))
1044                         break;
1045                 err = 0;
1046                 break;
1047
1048         case SIOCGPPPCSTATS:
1049                 memset(&cstats, 0, sizeof(cstats));
1050                 if (ppp->xc_state)
1051                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
1052                 if (ppp->rc_state)
1053                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
1054                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
1055                         break;
1056                 err = 0;
1057                 break;
1058
1059         case SIOCGPPPVER:
1060                 vers = PPP_VERSION;
1061                 if (copy_to_user(addr, vers, strlen(vers) + 1))
1062                         break;
1063                 err = 0;
1064                 break;
1065
1066         default:
1067                 err = -EINVAL;
1068         }
1069
1070         return err;
1071 }
1072
1073 static struct rtnl_link_stats64*
1074 ppp_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats64)
1075 {
1076         struct ppp *ppp = netdev_priv(dev);
1077
1078         ppp_recv_lock(ppp);
1079         stats64->rx_packets = ppp->stats64.rx_packets;
1080         stats64->rx_bytes   = ppp->stats64.rx_bytes;
1081         ppp_recv_unlock(ppp);
1082
1083         ppp_xmit_lock(ppp);
1084         stats64->tx_packets = ppp->stats64.tx_packets;
1085         stats64->tx_bytes   = ppp->stats64.tx_bytes;
1086         ppp_xmit_unlock(ppp);
1087
1088         stats64->rx_errors        = dev->stats.rx_errors;
1089         stats64->tx_errors        = dev->stats.tx_errors;
1090         stats64->rx_dropped       = dev->stats.rx_dropped;
1091         stats64->tx_dropped       = dev->stats.tx_dropped;
1092         stats64->rx_length_errors = dev->stats.rx_length_errors;
1093
1094         return stats64;
1095 }
1096
1097 static struct lock_class_key ppp_tx_busylock;
1098 static int ppp_dev_init(struct net_device *dev)
1099 {
1100         dev->qdisc_tx_busylock = &ppp_tx_busylock;
1101         return 0;
1102 }
1103
1104 static void ppp_dev_uninit(struct net_device *dev)
1105 {
1106         struct ppp *ppp = netdev_priv(dev);
1107         struct ppp_net *pn = ppp_pernet(ppp->ppp_net);
1108
1109         ppp_lock(ppp);
1110         ppp->closing = 1;
1111         ppp_unlock(ppp);
1112
1113         mutex_lock(&pn->all_ppp_mutex);
1114         unit_put(&pn->units_idr, ppp->file.index);
1115         mutex_unlock(&pn->all_ppp_mutex);
1116
1117         ppp->owner = NULL;
1118
1119         ppp->file.dead = 1;
1120         wake_up_interruptible(&ppp->file.rwait);
1121 }
1122
1123 static const struct net_device_ops ppp_netdev_ops = {
1124         .ndo_init        = ppp_dev_init,
1125         .ndo_uninit      = ppp_dev_uninit,
1126         .ndo_start_xmit  = ppp_start_xmit,
1127         .ndo_do_ioctl    = ppp_net_ioctl,
1128         .ndo_get_stats64 = ppp_get_stats64,
1129 };
1130
1131 static void ppp_setup(struct net_device *dev)
1132 {
1133         dev->netdev_ops = &ppp_netdev_ops;
1134         dev->hard_header_len = PPP_HDRLEN;
1135         dev->mtu = PPP_MRU;
1136         dev->addr_len = 0;
1137         dev->tx_queue_len = 3;
1138         dev->type = ARPHRD_PPP;
1139         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1140         dev->features |= NETIF_F_NETNS_LOCAL;
1141         netif_keep_dst(dev);
1142 }
1143
1144 /*
1145  * Transmit-side routines.
1146  */
1147
1148 /*
1149  * Called to do any work queued up on the transmit side
1150  * that can now be done.
1151  */
1152 static void
1153 ppp_xmit_process(struct ppp *ppp)
1154 {
1155         struct sk_buff *skb;
1156
1157         ppp_xmit_lock(ppp);
1158         if (!ppp->closing) {
1159                 ppp_push(ppp);
1160                 while (!ppp->xmit_pending &&
1161                        (skb = skb_dequeue(&ppp->file.xq)))
1162                         ppp_send_frame(ppp, skb);
1163                 /* If there's no work left to do, tell the core net
1164                    code that we can accept some more. */
1165                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1166                         netif_wake_queue(ppp->dev);
1167                 else
1168                         netif_stop_queue(ppp->dev);
1169         }
1170         ppp_xmit_unlock(ppp);
1171 }
1172
1173 static inline struct sk_buff *
1174 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1175 {
1176         struct sk_buff *new_skb;
1177         int len;
1178         int new_skb_size = ppp->dev->mtu +
1179                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1180         int compressor_skb_size = ppp->dev->mtu +
1181                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1182         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1183         if (!new_skb) {
1184                 if (net_ratelimit())
1185                         netdev_err(ppp->dev, "PPP: no memory (comp pkt)\n");
1186                 return NULL;
1187         }
1188         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1189                 skb_reserve(new_skb,
1190                             ppp->dev->hard_header_len - PPP_HDRLEN);
1191
1192         /* compressor still expects A/C bytes in hdr */
1193         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1194                                    new_skb->data, skb->len + 2,
1195                                    compressor_skb_size);
1196         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1197                 consume_skb(skb);
1198                 skb = new_skb;
1199                 skb_put(skb, len);
1200                 skb_pull(skb, 2);       /* pull off A/C bytes */
1201         } else if (len == 0) {
1202                 /* didn't compress, or CCP not up yet */
1203                 consume_skb(new_skb);
1204                 new_skb = skb;
1205         } else {
1206                 /*
1207                  * (len < 0)
1208                  * MPPE requires that we do not send unencrypted
1209                  * frames.  The compressor will return -1 if we
1210                  * should drop the frame.  We cannot simply test
1211                  * the compress_proto because MPPE and MPPC share
1212                  * the same number.
1213                  */
1214                 if (net_ratelimit())
1215                         netdev_err(ppp->dev, "ppp: compressor dropped pkt\n");
1216                 kfree_skb(skb);
1217                 consume_skb(new_skb);
1218                 new_skb = NULL;
1219         }
1220         return new_skb;
1221 }
1222
1223 /*
1224  * Compress and send a frame.
1225  * The caller should have locked the xmit path,
1226  * and xmit_pending should be 0.
1227  */
1228 static void
1229 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1230 {
1231         int proto = PPP_PROTO(skb);
1232         struct sk_buff *new_skb;
1233         int len;
1234         unsigned char *cp;
1235
1236         if (proto < 0x8000) {
1237 #ifdef CONFIG_PPP_FILTER
1238                 /* check if we should pass this packet */
1239                 /* the filter instructions are constructed assuming
1240                    a four-byte PPP header on each packet */
1241                 *skb_push(skb, 2) = 1;
1242                 if (ppp->pass_filter &&
1243                     BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
1244                         if (ppp->debug & 1)
1245                                 netdev_printk(KERN_DEBUG, ppp->dev,
1246                                               "PPP: outbound frame "
1247                                               "not passed\n");
1248                         kfree_skb(skb);
1249                         return;
1250                 }
1251                 /* if this packet passes the active filter, record the time */
1252                 if (!(ppp->active_filter &&
1253                       BPF_PROG_RUN(ppp->active_filter, skb) == 0))
1254                         ppp->last_xmit = jiffies;
1255                 skb_pull(skb, 2);
1256 #else
1257                 /* for data packets, record the time */
1258                 ppp->last_xmit = jiffies;
1259 #endif /* CONFIG_PPP_FILTER */
1260         }
1261
1262         ++ppp->stats64.tx_packets;
1263         ppp->stats64.tx_bytes += skb->len - 2;
1264
1265         switch (proto) {
1266         case PPP_IP:
1267                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1268                         break;
1269                 /* try to do VJ TCP header compression */
1270                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1271                                     GFP_ATOMIC);
1272                 if (!new_skb) {
1273                         netdev_err(ppp->dev, "PPP: no memory (VJ comp pkt)\n");
1274                         goto drop;
1275                 }
1276                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1277                 cp = skb->data + 2;
1278                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1279                                     new_skb->data + 2, &cp,
1280                                     !(ppp->flags & SC_NO_TCP_CCID));
1281                 if (cp == skb->data + 2) {
1282                         /* didn't compress */
1283                         consume_skb(new_skb);
1284                 } else {
1285                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1286                                 proto = PPP_VJC_COMP;
1287                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1288                         } else {
1289                                 proto = PPP_VJC_UNCOMP;
1290                                 cp[0] = skb->data[2];
1291                         }
1292                         consume_skb(skb);
1293                         skb = new_skb;
1294                         cp = skb_put(skb, len + 2);
1295                         cp[0] = 0;
1296                         cp[1] = proto;
1297                 }
1298                 break;
1299
1300         case PPP_CCP:
1301                 /* peek at outbound CCP frames */
1302                 ppp_ccp_peek(ppp, skb, 0);
1303                 break;
1304         }
1305
1306         /* try to do packet compression */
1307         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state &&
1308             proto != PPP_LCP && proto != PPP_CCP) {
1309                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1310                         if (net_ratelimit())
1311                                 netdev_err(ppp->dev,
1312                                            "ppp: compression required but "
1313                                            "down - pkt dropped.\n");
1314                         goto drop;
1315                 }
1316                 skb = pad_compress_skb(ppp, skb);
1317                 if (!skb)
1318                         goto drop;
1319         }
1320
1321         /*
1322          * If we are waiting for traffic (demand dialling),
1323          * queue it up for pppd to receive.
1324          */
1325         if (ppp->flags & SC_LOOP_TRAFFIC) {
1326                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1327                         goto drop;
1328                 skb_queue_tail(&ppp->file.rq, skb);
1329                 wake_up_interruptible(&ppp->file.rwait);
1330                 return;
1331         }
1332
1333         ppp->xmit_pending = skb;
1334         ppp_push(ppp);
1335         return;
1336
1337  drop:
1338         kfree_skb(skb);
1339         ++ppp->dev->stats.tx_errors;
1340 }
1341
1342 /*
1343  * Try to send the frame in xmit_pending.
1344  * The caller should have the xmit path locked.
1345  */
1346 static void
1347 ppp_push(struct ppp *ppp)
1348 {
1349         struct list_head *list;
1350         struct channel *pch;
1351         struct sk_buff *skb = ppp->xmit_pending;
1352
1353         if (!skb)
1354                 return;
1355
1356         list = &ppp->channels;
1357         if (list_empty(list)) {
1358                 /* nowhere to send the packet, just drop it */
1359                 ppp->xmit_pending = NULL;
1360                 kfree_skb(skb);
1361                 return;
1362         }
1363
1364         if ((ppp->flags & SC_MULTILINK) == 0) {
1365                 /* not doing multilink: send it down the first channel */
1366                 list = list->next;
1367                 pch = list_entry(list, struct channel, clist);
1368
1369                 spin_lock_bh(&pch->downl);
1370                 if (pch->chan) {
1371                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1372                                 ppp->xmit_pending = NULL;
1373                 } else {
1374                         /* channel got unregistered */
1375                         kfree_skb(skb);
1376                         ppp->xmit_pending = NULL;
1377                 }
1378                 spin_unlock_bh(&pch->downl);
1379                 return;
1380         }
1381
1382 #ifdef CONFIG_PPP_MULTILINK
1383         /* Multilink: fragment the packet over as many links
1384            as can take the packet at the moment. */
1385         if (!ppp_mp_explode(ppp, skb))
1386                 return;
1387 #endif /* CONFIG_PPP_MULTILINK */
1388
1389         ppp->xmit_pending = NULL;
1390         kfree_skb(skb);
1391 }
1392
1393 #ifdef CONFIG_PPP_MULTILINK
1394 static bool mp_protocol_compress __read_mostly = true;
1395 module_param(mp_protocol_compress, bool, S_IRUGO | S_IWUSR);
1396 MODULE_PARM_DESC(mp_protocol_compress,
1397                  "compress protocol id in multilink fragments");
1398
1399 /*
1400  * Divide a packet to be transmitted into fragments and
1401  * send them out the individual links.
1402  */
1403 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1404 {
1405         int len, totlen;
1406         int i, bits, hdrlen, mtu;
1407         int flen;
1408         int navail, nfree, nzero;
1409         int nbigger;
1410         int totspeed;
1411         int totfree;
1412         unsigned char *p, *q;
1413         struct list_head *list;
1414         struct channel *pch;
1415         struct sk_buff *frag;
1416         struct ppp_channel *chan;
1417
1418         totspeed = 0; /*total bitrate of the bundle*/
1419         nfree = 0; /* # channels which have no packet already queued */
1420         navail = 0; /* total # of usable channels (not deregistered) */
1421         nzero = 0; /* number of channels with zero speed associated*/
1422         totfree = 0; /*total # of channels available and
1423                                   *having no queued packets before
1424                                   *starting the fragmentation*/
1425
1426         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1427         i = 0;
1428         list_for_each_entry(pch, &ppp->channels, clist) {
1429                 if (pch->chan) {
1430                         pch->avail = 1;
1431                         navail++;
1432                         pch->speed = pch->chan->speed;
1433                 } else {
1434                         pch->avail = 0;
1435                 }
1436                 if (pch->avail) {
1437                         if (skb_queue_empty(&pch->file.xq) ||
1438                                 !pch->had_frag) {
1439                                         if (pch->speed == 0)
1440                                                 nzero++;
1441                                         else
1442                                                 totspeed += pch->speed;
1443
1444                                         pch->avail = 2;
1445                                         ++nfree;
1446                                         ++totfree;
1447                                 }
1448                         if (!pch->had_frag && i < ppp->nxchan)
1449                                 ppp->nxchan = i;
1450                 }
1451                 ++i;
1452         }
1453         /*
1454          * Don't start sending this packet unless at least half of
1455          * the channels are free.  This gives much better TCP
1456          * performance if we have a lot of channels.
1457          */
1458         if (nfree == 0 || nfree < navail / 2)
1459                 return 0; /* can't take now, leave it in xmit_pending */
1460
1461         /* Do protocol field compression */
1462         p = skb->data;
1463         len = skb->len;
1464         if (*p == 0 && mp_protocol_compress) {
1465                 ++p;
1466                 --len;
1467         }
1468
1469         totlen = len;
1470         nbigger = len % nfree;
1471
1472         /* skip to the channel after the one we last used
1473            and start at that one */
1474         list = &ppp->channels;
1475         for (i = 0; i < ppp->nxchan; ++i) {
1476                 list = list->next;
1477                 if (list == &ppp->channels) {
1478                         i = 0;
1479                         break;
1480                 }
1481         }
1482
1483         /* create a fragment for each channel */
1484         bits = B;
1485         while (len > 0) {
1486                 list = list->next;
1487                 if (list == &ppp->channels) {
1488                         i = 0;
1489                         continue;
1490                 }
1491                 pch = list_entry(list, struct channel, clist);
1492                 ++i;
1493                 if (!pch->avail)
1494                         continue;
1495
1496                 /*
1497                  * Skip this channel if it has a fragment pending already and
1498                  * we haven't given a fragment to all of the free channels.
1499                  */
1500                 if (pch->avail == 1) {
1501                         if (nfree > 0)
1502                                 continue;
1503                 } else {
1504                         pch->avail = 1;
1505                 }
1506
1507                 /* check the channel's mtu and whether it is still attached. */
1508                 spin_lock_bh(&pch->downl);
1509                 if (pch->chan == NULL) {
1510                         /* can't use this channel, it's being deregistered */
1511                         if (pch->speed == 0)
1512                                 nzero--;
1513                         else
1514                                 totspeed -= pch->speed;
1515
1516                         spin_unlock_bh(&pch->downl);
1517                         pch->avail = 0;
1518                         totlen = len;
1519                         totfree--;
1520                         nfree--;
1521                         if (--navail == 0)
1522                                 break;
1523                         continue;
1524                 }
1525
1526                 /*
1527                 *if the channel speed is not set divide
1528                 *the packet evenly among the free channels;
1529                 *otherwise divide it according to the speed
1530                 *of the channel we are going to transmit on
1531                 */
1532                 flen = len;
1533                 if (nfree > 0) {
1534                         if (pch->speed == 0) {
1535                                 flen = len/nfree;
1536                                 if (nbigger > 0) {
1537                                         flen++;
1538                                         nbigger--;
1539                                 }
1540                         } else {
1541                                 flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
1542                                         ((totspeed*totfree)/pch->speed)) - hdrlen;
1543                                 if (nbigger > 0) {
1544                                         flen += ((totfree - nzero)*pch->speed)/totspeed;
1545                                         nbigger -= ((totfree - nzero)*pch->speed)/
1546                                                         totspeed;
1547                                 }
1548                         }
1549                         nfree--;
1550                 }
1551
1552                 /*
1553                  *check if we are on the last channel or
1554                  *we exceded the length of the data to
1555                  *fragment
1556                  */
1557                 if ((nfree <= 0) || (flen > len))
1558                         flen = len;
1559                 /*
1560                  *it is not worth to tx on slow channels:
1561                  *in that case from the resulting flen according to the
1562                  *above formula will be equal or less than zero.
1563                  *Skip the channel in this case
1564                  */
1565                 if (flen <= 0) {
1566                         pch->avail = 2;
1567                         spin_unlock_bh(&pch->downl);
1568                         continue;
1569                 }
1570
1571                 /*
1572                  * hdrlen includes the 2-byte PPP protocol field, but the
1573                  * MTU counts only the payload excluding the protocol field.
1574                  * (RFC1661 Section 2)
1575                  */
1576                 mtu = pch->chan->mtu - (hdrlen - 2);
1577                 if (mtu < 4)
1578                         mtu = 4;
1579                 if (flen > mtu)
1580                         flen = mtu;
1581                 if (flen == len)
1582                         bits |= E;
1583                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1584                 if (!frag)
1585                         goto noskb;
1586                 q = skb_put(frag, flen + hdrlen);
1587
1588                 /* make the MP header */
1589                 put_unaligned_be16(PPP_MP, q);
1590                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1591                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1592                         q[3] = ppp->nxseq;
1593                 } else {
1594                         q[2] = bits;
1595                         q[3] = ppp->nxseq >> 16;
1596                         q[4] = ppp->nxseq >> 8;
1597                         q[5] = ppp->nxseq;
1598                 }
1599
1600                 memcpy(q + hdrlen, p, flen);
1601
1602                 /* try to send it down the channel */
1603                 chan = pch->chan;
1604                 if (!skb_queue_empty(&pch->file.xq) ||
1605                         !chan->ops->start_xmit(chan, frag))
1606                         skb_queue_tail(&pch->file.xq, frag);
1607                 pch->had_frag = 1;
1608                 p += flen;
1609                 len -= flen;
1610                 ++ppp->nxseq;
1611                 bits = 0;
1612                 spin_unlock_bh(&pch->downl);
1613         }
1614         ppp->nxchan = i;
1615
1616         return 1;
1617
1618  noskb:
1619         spin_unlock_bh(&pch->downl);
1620         if (ppp->debug & 1)
1621                 netdev_err(ppp->dev, "PPP: no memory (fragment)\n");
1622         ++ppp->dev->stats.tx_errors;
1623         ++ppp->nxseq;
1624         return 1;       /* abandon the frame */
1625 }
1626 #endif /* CONFIG_PPP_MULTILINK */
1627
1628 /*
1629  * Try to send data out on a channel.
1630  */
1631 static void
1632 ppp_channel_push(struct channel *pch)
1633 {
1634         struct sk_buff *skb;
1635         struct ppp *ppp;
1636
1637         spin_lock_bh(&pch->downl);
1638         if (pch->chan) {
1639                 while (!skb_queue_empty(&pch->file.xq)) {
1640                         skb = skb_dequeue(&pch->file.xq);
1641                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1642                                 /* put the packet back and try again later */
1643                                 skb_queue_head(&pch->file.xq, skb);
1644                                 break;
1645                         }
1646                 }
1647         } else {
1648                 /* channel got deregistered */
1649                 skb_queue_purge(&pch->file.xq);
1650         }
1651         spin_unlock_bh(&pch->downl);
1652         /* see if there is anything from the attached unit to be sent */
1653         if (skb_queue_empty(&pch->file.xq)) {
1654                 read_lock_bh(&pch->upl);
1655                 ppp = pch->ppp;
1656                 if (ppp)
1657                         ppp_xmit_process(ppp);
1658                 read_unlock_bh(&pch->upl);
1659         }
1660 }
1661
1662 /*
1663  * Receive-side routines.
1664  */
1665
1666 struct ppp_mp_skb_parm {
1667         u32             sequence;
1668         u8              BEbits;
1669 };
1670 #define PPP_MP_CB(skb)  ((struct ppp_mp_skb_parm *)((skb)->cb))
1671
1672 static inline void
1673 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1674 {
1675         ppp_recv_lock(ppp);
1676         if (!ppp->closing)
1677                 ppp_receive_frame(ppp, skb, pch);
1678         else
1679                 kfree_skb(skb);
1680         ppp_recv_unlock(ppp);
1681 }
1682
1683 void
1684 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1685 {
1686         struct channel *pch = chan->ppp;
1687         int proto;
1688
1689         if (!pch) {
1690                 kfree_skb(skb);
1691                 return;
1692         }
1693
1694         read_lock_bh(&pch->upl);
1695         if (!pskb_may_pull(skb, 2)) {
1696                 kfree_skb(skb);
1697                 if (pch->ppp) {
1698                         ++pch->ppp->dev->stats.rx_length_errors;
1699                         ppp_receive_error(pch->ppp);
1700                 }
1701                 goto done;
1702         }
1703
1704         proto = PPP_PROTO(skb);
1705         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1706                 /* put it on the channel queue */
1707                 skb_queue_tail(&pch->file.rq, skb);
1708                 /* drop old frames if queue too long */
1709                 while (pch->file.rq.qlen > PPP_MAX_RQLEN &&
1710                        (skb = skb_dequeue(&pch->file.rq)))
1711                         kfree_skb(skb);
1712                 wake_up_interruptible(&pch->file.rwait);
1713         } else {
1714                 ppp_do_recv(pch->ppp, skb, pch);
1715         }
1716
1717 done:
1718         read_unlock_bh(&pch->upl);
1719 }
1720
1721 /* Put a 0-length skb in the receive queue as an error indication */
1722 void
1723 ppp_input_error(struct ppp_channel *chan, int code)
1724 {
1725         struct channel *pch = chan->ppp;
1726         struct sk_buff *skb;
1727
1728         if (!pch)
1729                 return;
1730
1731         read_lock_bh(&pch->upl);
1732         if (pch->ppp) {
1733                 skb = alloc_skb(0, GFP_ATOMIC);
1734                 if (skb) {
1735                         skb->len = 0;           /* probably unnecessary */
1736                         skb->cb[0] = code;
1737                         ppp_do_recv(pch->ppp, skb, pch);
1738                 }
1739         }
1740         read_unlock_bh(&pch->upl);
1741 }
1742
1743 /*
1744  * We come in here to process a received frame.
1745  * The receive side of the ppp unit is locked.
1746  */
1747 static void
1748 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1749 {
1750         /* note: a 0-length skb is used as an error indication */
1751         if (skb->len > 0) {
1752                 skb_checksum_complete_unset(skb);
1753 #ifdef CONFIG_PPP_MULTILINK
1754                 /* XXX do channel-level decompression here */
1755                 if (PPP_PROTO(skb) == PPP_MP)
1756                         ppp_receive_mp_frame(ppp, skb, pch);
1757                 else
1758 #endif /* CONFIG_PPP_MULTILINK */
1759                         ppp_receive_nonmp_frame(ppp, skb);
1760         } else {
1761                 kfree_skb(skb);
1762                 ppp_receive_error(ppp);
1763         }
1764 }
1765
1766 static void
1767 ppp_receive_error(struct ppp *ppp)
1768 {
1769         ++ppp->dev->stats.rx_errors;
1770         if (ppp->vj)
1771                 slhc_toss(ppp->vj);
1772 }
1773
1774 static void
1775 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1776 {
1777         struct sk_buff *ns;
1778         int proto, len, npi;
1779
1780         /*
1781          * Decompress the frame, if compressed.
1782          * Note that some decompressors need to see uncompressed frames
1783          * that come in as well as compressed frames.
1784          */
1785         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN) &&
1786             (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1787                 skb = ppp_decompress_frame(ppp, skb);
1788
1789         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1790                 goto err;
1791
1792         proto = PPP_PROTO(skb);
1793         switch (proto) {
1794         case PPP_VJC_COMP:
1795                 /* decompress VJ compressed packets */
1796                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1797                         goto err;
1798
1799                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1800                         /* copy to a new sk_buff with more tailroom */
1801                         ns = dev_alloc_skb(skb->len + 128);
1802                         if (!ns) {
1803                                 netdev_err(ppp->dev, "PPP: no memory "
1804                                            "(VJ decomp)\n");
1805                                 goto err;
1806                         }
1807                         skb_reserve(ns, 2);
1808                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1809                         consume_skb(skb);
1810                         skb = ns;
1811                 }
1812                 else
1813                         skb->ip_summed = CHECKSUM_NONE;
1814
1815                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1816                 if (len <= 0) {
1817                         netdev_printk(KERN_DEBUG, ppp->dev,
1818                                       "PPP: VJ decompression error\n");
1819                         goto err;
1820                 }
1821                 len += 2;
1822                 if (len > skb->len)
1823                         skb_put(skb, len - skb->len);
1824                 else if (len < skb->len)
1825                         skb_trim(skb, len);
1826                 proto = PPP_IP;
1827                 break;
1828
1829         case PPP_VJC_UNCOMP:
1830                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1831                         goto err;
1832
1833                 /* Until we fix the decompressor need to make sure
1834                  * data portion is linear.
1835                  */
1836                 if (!pskb_may_pull(skb, skb->len))
1837                         goto err;
1838
1839                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1840                         netdev_err(ppp->dev, "PPP: VJ uncompressed error\n");
1841                         goto err;
1842                 }
1843                 proto = PPP_IP;
1844                 break;
1845
1846         case PPP_CCP:
1847                 ppp_ccp_peek(ppp, skb, 1);
1848                 break;
1849         }
1850
1851         ++ppp->stats64.rx_packets;
1852         ppp->stats64.rx_bytes += skb->len - 2;
1853
1854         npi = proto_to_npindex(proto);
1855         if (npi < 0) {
1856                 /* control or unknown frame - pass it to pppd */
1857                 skb_queue_tail(&ppp->file.rq, skb);
1858                 /* limit queue length by dropping old frames */
1859                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN &&
1860                        (skb = skb_dequeue(&ppp->file.rq)))
1861                         kfree_skb(skb);
1862                 /* wake up any process polling or blocking on read */
1863                 wake_up_interruptible(&ppp->file.rwait);
1864
1865         } else {
1866                 /* network protocol frame - give it to the kernel */
1867
1868 #ifdef CONFIG_PPP_FILTER
1869                 /* check if the packet passes the pass and active filters */
1870                 /* the filter instructions are constructed assuming
1871                    a four-byte PPP header on each packet */
1872                 if (ppp->pass_filter || ppp->active_filter) {
1873                         if (skb_unclone(skb, GFP_ATOMIC))
1874                                 goto err;
1875
1876                         *skb_push(skb, 2) = 0;
1877                         if (ppp->pass_filter &&
1878                             BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
1879                                 if (ppp->debug & 1)
1880                                         netdev_printk(KERN_DEBUG, ppp->dev,
1881                                                       "PPP: inbound frame "
1882                                                       "not passed\n");
1883                                 kfree_skb(skb);
1884                                 return;
1885                         }
1886                         if (!(ppp->active_filter &&
1887                               BPF_PROG_RUN(ppp->active_filter, skb) == 0))
1888                                 ppp->last_recv = jiffies;
1889                         __skb_pull(skb, 2);
1890                 } else
1891 #endif /* CONFIG_PPP_FILTER */
1892                         ppp->last_recv = jiffies;
1893
1894                 if ((ppp->dev->flags & IFF_UP) == 0 ||
1895                     ppp->npmode[npi] != NPMODE_PASS) {
1896                         kfree_skb(skb);
1897                 } else {
1898                         /* chop off protocol */
1899                         skb_pull_rcsum(skb, 2);
1900                         skb->dev = ppp->dev;
1901                         skb->protocol = htons(npindex_to_ethertype[npi]);
1902                         skb_reset_mac_header(skb);
1903                         netif_rx(skb);
1904                 }
1905         }
1906         return;
1907
1908  err:
1909         kfree_skb(skb);
1910         ppp_receive_error(ppp);
1911 }
1912
1913 static struct sk_buff *
1914 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1915 {
1916         int proto = PPP_PROTO(skb);
1917         struct sk_buff *ns;
1918         int len;
1919
1920         /* Until we fix all the decompressor's need to make sure
1921          * data portion is linear.
1922          */
1923         if (!pskb_may_pull(skb, skb->len))
1924                 goto err;
1925
1926         if (proto == PPP_COMP) {
1927                 int obuff_size;
1928
1929                 switch(ppp->rcomp->compress_proto) {
1930                 case CI_MPPE:
1931                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1932                         break;
1933                 default:
1934                         obuff_size = ppp->mru + PPP_HDRLEN;
1935                         break;
1936                 }
1937
1938                 ns = dev_alloc_skb(obuff_size);
1939                 if (!ns) {
1940                         netdev_err(ppp->dev, "ppp_decompress_frame: "
1941                                    "no memory\n");
1942                         goto err;
1943                 }
1944                 /* the decompressor still expects the A/C bytes in the hdr */
1945                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1946                                 skb->len + 2, ns->data, obuff_size);
1947                 if (len < 0) {
1948                         /* Pass the compressed frame to pppd as an
1949                            error indication. */
1950                         if (len == DECOMP_FATALERROR)
1951                                 ppp->rstate |= SC_DC_FERROR;
1952                         kfree_skb(ns);
1953                         goto err;
1954                 }
1955
1956                 consume_skb(skb);
1957                 skb = ns;
1958                 skb_put(skb, len);
1959                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1960
1961         } else {
1962                 /* Uncompressed frame - pass to decompressor so it
1963                    can update its dictionary if necessary. */
1964                 if (ppp->rcomp->incomp)
1965                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1966                                            skb->len + 2);
1967         }
1968
1969         return skb;
1970
1971  err:
1972         ppp->rstate |= SC_DC_ERROR;
1973         ppp_receive_error(ppp);
1974         return skb;
1975 }
1976
1977 #ifdef CONFIG_PPP_MULTILINK
1978 /*
1979  * Receive a multilink frame.
1980  * We put it on the reconstruction queue and then pull off
1981  * as many completed frames as we can.
1982  */
1983 static void
1984 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1985 {
1986         u32 mask, seq;
1987         struct channel *ch;
1988         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1989
1990         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1991                 goto err;               /* no good, throw it away */
1992
1993         /* Decode sequence number and begin/end bits */
1994         if (ppp->flags & SC_MP_SHORTSEQ) {
1995                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1996                 mask = 0xfff;
1997         } else {
1998                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1999                 mask = 0xffffff;
2000         }
2001         PPP_MP_CB(skb)->BEbits = skb->data[2];
2002         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
2003
2004         /*
2005          * Do protocol ID decompression on the first fragment of each packet.
2006          */
2007         if ((PPP_MP_CB(skb)->BEbits & B) && (skb->data[0] & 1))
2008                 *skb_push(skb, 1) = 0;
2009
2010         /*
2011          * Expand sequence number to 32 bits, making it as close
2012          * as possible to ppp->minseq.
2013          */
2014         seq |= ppp->minseq & ~mask;
2015         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
2016                 seq += mask + 1;
2017         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
2018                 seq -= mask + 1;        /* should never happen */
2019         PPP_MP_CB(skb)->sequence = seq;
2020         pch->lastseq = seq;
2021
2022         /*
2023          * If this packet comes before the next one we were expecting,
2024          * drop it.
2025          */
2026         if (seq_before(seq, ppp->nextseq)) {
2027                 kfree_skb(skb);
2028                 ++ppp->dev->stats.rx_dropped;
2029                 ppp_receive_error(ppp);
2030                 return;
2031         }
2032
2033         /*
2034          * Reevaluate minseq, the minimum over all channels of the
2035          * last sequence number received on each channel.  Because of
2036          * the increasing sequence number rule, we know that any fragment
2037          * before `minseq' which hasn't arrived is never going to arrive.
2038          * The list of channels can't change because we have the receive
2039          * side of the ppp unit locked.
2040          */
2041         list_for_each_entry(ch, &ppp->channels, clist) {
2042                 if (seq_before(ch->lastseq, seq))
2043                         seq = ch->lastseq;
2044         }
2045         if (seq_before(ppp->minseq, seq))
2046                 ppp->minseq = seq;
2047
2048         /* Put the fragment on the reconstruction queue */
2049         ppp_mp_insert(ppp, skb);
2050
2051         /* If the queue is getting long, don't wait any longer for packets
2052            before the start of the queue. */
2053         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
2054                 struct sk_buff *mskb = skb_peek(&ppp->mrq);
2055                 if (seq_before(ppp->minseq, PPP_MP_CB(mskb)->sequence))
2056                         ppp->minseq = PPP_MP_CB(mskb)->sequence;
2057         }
2058
2059         /* Pull completed packets off the queue and receive them. */
2060         while ((skb = ppp_mp_reconstruct(ppp))) {
2061                 if (pskb_may_pull(skb, 2))
2062                         ppp_receive_nonmp_frame(ppp, skb);
2063                 else {
2064                         ++ppp->dev->stats.rx_length_errors;
2065                         kfree_skb(skb);
2066                         ppp_receive_error(ppp);
2067                 }
2068         }
2069
2070         return;
2071
2072  err:
2073         kfree_skb(skb);
2074         ppp_receive_error(ppp);
2075 }
2076
2077 /*
2078  * Insert a fragment on the MP reconstruction queue.
2079  * The queue is ordered by increasing sequence number.
2080  */
2081 static void
2082 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
2083 {
2084         struct sk_buff *p;
2085         struct sk_buff_head *list = &ppp->mrq;
2086         u32 seq = PPP_MP_CB(skb)->sequence;
2087
2088         /* N.B. we don't need to lock the list lock because we have the
2089            ppp unit receive-side lock. */
2090         skb_queue_walk(list, p) {
2091                 if (seq_before(seq, PPP_MP_CB(p)->sequence))
2092                         break;
2093         }
2094         __skb_queue_before(list, p, skb);
2095 }
2096
2097 /*
2098  * Reconstruct a packet from the MP fragment queue.
2099  * We go through increasing sequence numbers until we find a
2100  * complete packet, or we get to the sequence number for a fragment
2101  * which hasn't arrived but might still do so.
2102  */
2103 static struct sk_buff *
2104 ppp_mp_reconstruct(struct ppp *ppp)
2105 {
2106         u32 seq = ppp->nextseq;
2107         u32 minseq = ppp->minseq;
2108         struct sk_buff_head *list = &ppp->mrq;
2109         struct sk_buff *p, *tmp;
2110         struct sk_buff *head, *tail;
2111         struct sk_buff *skb = NULL;
2112         int lost = 0, len = 0;
2113
2114         if (ppp->mrru == 0)     /* do nothing until mrru is set */
2115                 return NULL;
2116         head = list->next;
2117         tail = NULL;
2118         skb_queue_walk_safe(list, p, tmp) {
2119         again:
2120                 if (seq_before(PPP_MP_CB(p)->sequence, seq)) {
2121                         /* this can't happen, anyway ignore the skb */
2122                         netdev_err(ppp->dev, "ppp_mp_reconstruct bad "
2123                                    "seq %u < %u\n",
2124                                    PPP_MP_CB(p)->sequence, seq);
2125                         __skb_unlink(p, list);
2126                         kfree_skb(p);
2127                         continue;
2128                 }
2129                 if (PPP_MP_CB(p)->sequence != seq) {
2130                         u32 oldseq;
2131                         /* Fragment `seq' is missing.  If it is after
2132                            minseq, it might arrive later, so stop here. */
2133                         if (seq_after(seq, minseq))
2134                                 break;
2135                         /* Fragment `seq' is lost, keep going. */
2136                         lost = 1;
2137                         oldseq = seq;
2138                         seq = seq_before(minseq, PPP_MP_CB(p)->sequence)?
2139                                 minseq + 1: PPP_MP_CB(p)->sequence;
2140
2141                         if (ppp->debug & 1)
2142                                 netdev_printk(KERN_DEBUG, ppp->dev,
2143                                               "lost frag %u..%u\n",
2144                                               oldseq, seq-1);
2145
2146                         goto again;
2147                 }
2148
2149                 /*
2150                  * At this point we know that all the fragments from
2151                  * ppp->nextseq to seq are either present or lost.
2152                  * Also, there are no complete packets in the queue
2153                  * that have no missing fragments and end before this
2154                  * fragment.
2155                  */
2156
2157                 /* B bit set indicates this fragment starts a packet */
2158                 if (PPP_MP_CB(p)->BEbits & B) {
2159                         head = p;
2160                         lost = 0;
2161                         len = 0;
2162                 }
2163
2164                 len += p->len;
2165
2166                 /* Got a complete packet yet? */
2167                 if (lost == 0 && (PPP_MP_CB(p)->BEbits & E) &&
2168                     (PPP_MP_CB(head)->BEbits & B)) {
2169                         if (len > ppp->mrru + 2) {
2170                                 ++ppp->dev->stats.rx_length_errors;
2171                                 netdev_printk(KERN_DEBUG, ppp->dev,
2172                                               "PPP: reconstructed packet"
2173                                               " is too long (%d)\n", len);
2174                         } else {
2175                                 tail = p;
2176                                 break;
2177                         }
2178                         ppp->nextseq = seq + 1;
2179                 }
2180
2181                 /*
2182                  * If this is the ending fragment of a packet,
2183                  * and we haven't found a complete valid packet yet,
2184                  * we can discard up to and including this fragment.
2185                  */
2186                 if (PPP_MP_CB(p)->BEbits & E) {
2187                         struct sk_buff *tmp2;
2188
2189                         skb_queue_reverse_walk_from_safe(list, p, tmp2) {
2190                                 if (ppp->debug & 1)
2191                                         netdev_printk(KERN_DEBUG, ppp->dev,
2192                                                       "discarding frag %u\n",
2193                                                       PPP_MP_CB(p)->sequence);
2194                                 __skb_unlink(p, list);
2195                                 kfree_skb(p);
2196                         }
2197                         head = skb_peek(list);
2198                         if (!head)
2199                                 break;
2200                 }
2201                 ++seq;
2202         }
2203
2204         /* If we have a complete packet, copy it all into one skb. */
2205         if (tail != NULL) {
2206                 /* If we have discarded any fragments,
2207                    signal a receive error. */
2208                 if (PPP_MP_CB(head)->sequence != ppp->nextseq) {
2209                         skb_queue_walk_safe(list, p, tmp) {
2210                                 if (p == head)
2211                                         break;
2212                                 if (ppp->debug & 1)
2213                                         netdev_printk(KERN_DEBUG, ppp->dev,
2214                                                       "discarding frag %u\n",
2215                                                       PPP_MP_CB(p)->sequence);
2216                                 __skb_unlink(p, list);
2217                                 kfree_skb(p);
2218                         }
2219
2220                         if (ppp->debug & 1)
2221                                 netdev_printk(KERN_DEBUG, ppp->dev,
2222                                               "  missed pkts %u..%u\n",
2223                                               ppp->nextseq,
2224                                               PPP_MP_CB(head)->sequence-1);
2225                         ++ppp->dev->stats.rx_dropped;
2226                         ppp_receive_error(ppp);
2227                 }
2228
2229                 skb = head;
2230                 if (head != tail) {
2231                         struct sk_buff **fragpp = &skb_shinfo(skb)->frag_list;
2232                         p = skb_queue_next(list, head);
2233                         __skb_unlink(skb, list);
2234                         skb_queue_walk_from_safe(list, p, tmp) {
2235                                 __skb_unlink(p, list);
2236                                 *fragpp = p;
2237                                 p->next = NULL;
2238                                 fragpp = &p->next;
2239
2240                                 skb->len += p->len;
2241                                 skb->data_len += p->len;
2242                                 skb->truesize += p->truesize;
2243
2244                                 if (p == tail)
2245                                         break;
2246                         }
2247                 } else {
2248                         __skb_unlink(skb, list);
2249                 }
2250
2251                 ppp->nextseq = PPP_MP_CB(tail)->sequence + 1;
2252         }
2253
2254         return skb;
2255 }
2256 #endif /* CONFIG_PPP_MULTILINK */
2257
2258 /*
2259  * Channel interface.
2260  */
2261
2262 /* Create a new, unattached ppp channel. */
2263 int ppp_register_channel(struct ppp_channel *chan)
2264 {
2265         return ppp_register_net_channel(current->nsproxy->net_ns, chan);
2266 }
2267
2268 /* Create a new, unattached ppp channel for specified net. */
2269 int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
2270 {
2271         struct channel *pch;
2272         struct ppp_net *pn;
2273
2274         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2275         if (!pch)
2276                 return -ENOMEM;
2277
2278         pn = ppp_pernet(net);
2279
2280         pch->ppp = NULL;
2281         pch->chan = chan;
2282         pch->chan_net = net;
2283         chan->ppp = pch;
2284         init_ppp_file(&pch->file, CHANNEL);
2285         pch->file.hdrlen = chan->hdrlen;
2286 #ifdef CONFIG_PPP_MULTILINK
2287         pch->lastseq = -1;
2288 #endif /* CONFIG_PPP_MULTILINK */
2289         init_rwsem(&pch->chan_sem);
2290         spin_lock_init(&pch->downl);
2291         rwlock_init(&pch->upl);
2292
2293         spin_lock_bh(&pn->all_channels_lock);
2294         pch->file.index = ++pn->last_channel_index;
2295         list_add(&pch->list, &pn->new_channels);
2296         atomic_inc(&channel_count);
2297         spin_unlock_bh(&pn->all_channels_lock);
2298
2299         return 0;
2300 }
2301
2302 /*
2303  * Return the index of a channel.
2304  */
2305 int ppp_channel_index(struct ppp_channel *chan)
2306 {
2307         struct channel *pch = chan->ppp;
2308
2309         if (pch)
2310                 return pch->file.index;
2311         return -1;
2312 }
2313
2314 /*
2315  * Return the PPP unit number to which a channel is connected.
2316  */
2317 int ppp_unit_number(struct ppp_channel *chan)
2318 {
2319         struct channel *pch = chan->ppp;
2320         int unit = -1;
2321
2322         if (pch) {
2323                 read_lock_bh(&pch->upl);
2324                 if (pch->ppp)
2325                         unit = pch->ppp->file.index;
2326                 read_unlock_bh(&pch->upl);
2327         }
2328         return unit;
2329 }
2330
2331 /*
2332  * Return the PPP device interface name of a channel.
2333  */
2334 char *ppp_dev_name(struct ppp_channel *chan)
2335 {
2336         struct channel *pch = chan->ppp;
2337         char *name = NULL;
2338
2339         if (pch) {
2340                 read_lock_bh(&pch->upl);
2341                 if (pch->ppp && pch->ppp->dev)
2342                         name = pch->ppp->dev->name;
2343                 read_unlock_bh(&pch->upl);
2344         }
2345         return name;
2346 }
2347
2348
2349 /*
2350  * Disconnect a channel from the generic layer.
2351  * This must be called in process context.
2352  */
2353 void
2354 ppp_unregister_channel(struct ppp_channel *chan)
2355 {
2356         struct channel *pch = chan->ppp;
2357         struct ppp_net *pn;
2358
2359         if (!pch)
2360                 return;         /* should never happen */
2361
2362         chan->ppp = NULL;
2363
2364         /*
2365          * This ensures that we have returned from any calls into the
2366          * the channel's start_xmit or ioctl routine before we proceed.
2367          */
2368         down_write(&pch->chan_sem);
2369         spin_lock_bh(&pch->downl);
2370         pch->chan = NULL;
2371         spin_unlock_bh(&pch->downl);
2372         up_write(&pch->chan_sem);
2373         ppp_disconnect_channel(pch);
2374
2375         pn = ppp_pernet(pch->chan_net);
2376         spin_lock_bh(&pn->all_channels_lock);
2377         list_del(&pch->list);
2378         spin_unlock_bh(&pn->all_channels_lock);
2379
2380         pch->file.dead = 1;
2381         wake_up_interruptible(&pch->file.rwait);
2382         if (atomic_dec_and_test(&pch->file.refcnt))
2383                 ppp_destroy_channel(pch);
2384 }
2385
2386 /*
2387  * Callback from a channel when it can accept more to transmit.
2388  * This should be called at BH/softirq level, not interrupt level.
2389  */
2390 void
2391 ppp_output_wakeup(struct ppp_channel *chan)
2392 {
2393         struct channel *pch = chan->ppp;
2394
2395         if (!pch)
2396                 return;
2397         ppp_channel_push(pch);
2398 }
2399
2400 /*
2401  * Compression control.
2402  */
2403
2404 /* Process the PPPIOCSCOMPRESS ioctl. */
2405 static int
2406 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2407 {
2408         int err;
2409         struct compressor *cp, *ocomp;
2410         struct ppp_option_data data;
2411         void *state, *ostate;
2412         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2413
2414         err = -EFAULT;
2415         if (copy_from_user(&data, (void __user *) arg, sizeof(data)) ||
2416             (data.length <= CCP_MAX_OPTION_LENGTH &&
2417              copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2418                 goto out;
2419         err = -EINVAL;
2420         if (data.length > CCP_MAX_OPTION_LENGTH ||
2421             ccp_option[1] < 2 || ccp_option[1] > data.length)
2422                 goto out;
2423
2424         cp = try_then_request_module(
2425                 find_compressor(ccp_option[0]),
2426                 "ppp-compress-%d", ccp_option[0]);
2427         if (!cp)
2428                 goto out;
2429
2430         err = -ENOBUFS;
2431         if (data.transmit) {
2432                 state = cp->comp_alloc(ccp_option, data.length);
2433                 if (state) {
2434                         ppp_xmit_lock(ppp);
2435                         ppp->xstate &= ~SC_COMP_RUN;
2436                         ocomp = ppp->xcomp;
2437                         ostate = ppp->xc_state;
2438                         ppp->xcomp = cp;
2439                         ppp->xc_state = state;
2440                         ppp_xmit_unlock(ppp);
2441                         if (ostate) {
2442                                 ocomp->comp_free(ostate);
2443                                 module_put(ocomp->owner);
2444                         }
2445                         err = 0;
2446                 } else
2447                         module_put(cp->owner);
2448
2449         } else {
2450                 state = cp->decomp_alloc(ccp_option, data.length);
2451                 if (state) {
2452                         ppp_recv_lock(ppp);
2453                         ppp->rstate &= ~SC_DECOMP_RUN;
2454                         ocomp = ppp->rcomp;
2455                         ostate = ppp->rc_state;
2456                         ppp->rcomp = cp;
2457                         ppp->rc_state = state;
2458                         ppp_recv_unlock(ppp);
2459                         if (ostate) {
2460                                 ocomp->decomp_free(ostate);
2461                                 module_put(ocomp->owner);
2462                         }
2463                         err = 0;
2464                 } else
2465                         module_put(cp->owner);
2466         }
2467
2468  out:
2469         return err;
2470 }
2471
2472 /*
2473  * Look at a CCP packet and update our state accordingly.
2474  * We assume the caller has the xmit or recv path locked.
2475  */
2476 static void
2477 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2478 {
2479         unsigned char *dp;
2480         int len;
2481
2482         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2483                 return; /* no header */
2484         dp = skb->data + 2;
2485
2486         switch (CCP_CODE(dp)) {
2487         case CCP_CONFREQ:
2488
2489                 /* A ConfReq starts negotiation of compression
2490                  * in one direction of transmission,
2491                  * and hence brings it down...but which way?
2492                  *
2493                  * Remember:
2494                  * A ConfReq indicates what the sender would like to receive
2495                  */
2496                 if(inbound)
2497                         /* He is proposing what I should send */
2498                         ppp->xstate &= ~SC_COMP_RUN;
2499                 else
2500                         /* I am proposing to what he should send */
2501                         ppp->rstate &= ~SC_DECOMP_RUN;
2502
2503                 break;
2504
2505         case CCP_TERMREQ:
2506         case CCP_TERMACK:
2507                 /*
2508                  * CCP is going down, both directions of transmission
2509                  */
2510                 ppp->rstate &= ~SC_DECOMP_RUN;
2511                 ppp->xstate &= ~SC_COMP_RUN;
2512                 break;
2513
2514         case CCP_CONFACK:
2515                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2516                         break;
2517                 len = CCP_LENGTH(dp);
2518                 if (!pskb_may_pull(skb, len + 2))
2519                         return;         /* too short */
2520                 dp += CCP_HDRLEN;
2521                 len -= CCP_HDRLEN;
2522                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2523                         break;
2524                 if (inbound) {
2525                         /* we will start receiving compressed packets */
2526                         if (!ppp->rc_state)
2527                                 break;
2528                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2529                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2530                                 ppp->rstate |= SC_DECOMP_RUN;
2531                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2532                         }
2533                 } else {
2534                         /* we will soon start sending compressed packets */
2535                         if (!ppp->xc_state)
2536                                 break;
2537                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2538                                         ppp->file.index, 0, ppp->debug))
2539                                 ppp->xstate |= SC_COMP_RUN;
2540                 }
2541                 break;
2542
2543         case CCP_RESETACK:
2544                 /* reset the [de]compressor */
2545                 if ((ppp->flags & SC_CCP_UP) == 0)
2546                         break;
2547                 if (inbound) {
2548                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2549                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2550                                 ppp->rstate &= ~SC_DC_ERROR;
2551                         }
2552                 } else {
2553                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2554                                 ppp->xcomp->comp_reset(ppp->xc_state);
2555                 }
2556                 break;
2557         }
2558 }
2559
2560 /* Free up compression resources. */
2561 static void
2562 ppp_ccp_closed(struct ppp *ppp)
2563 {
2564         void *xstate, *rstate;
2565         struct compressor *xcomp, *rcomp;
2566
2567         ppp_lock(ppp);
2568         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2569         ppp->xstate = 0;
2570         xcomp = ppp->xcomp;
2571         xstate = ppp->xc_state;
2572         ppp->xc_state = NULL;
2573         ppp->rstate = 0;
2574         rcomp = ppp->rcomp;
2575         rstate = ppp->rc_state;
2576         ppp->rc_state = NULL;
2577         ppp_unlock(ppp);
2578
2579         if (xstate) {
2580                 xcomp->comp_free(xstate);
2581                 module_put(xcomp->owner);
2582         }
2583         if (rstate) {
2584                 rcomp->decomp_free(rstate);
2585                 module_put(rcomp->owner);
2586         }
2587 }
2588
2589 /* List of compressors. */
2590 static LIST_HEAD(compressor_list);
2591 static DEFINE_SPINLOCK(compressor_list_lock);
2592
2593 struct compressor_entry {
2594         struct list_head list;
2595         struct compressor *comp;
2596 };
2597
2598 static struct compressor_entry *
2599 find_comp_entry(int proto)
2600 {
2601         struct compressor_entry *ce;
2602
2603         list_for_each_entry(ce, &compressor_list, list) {
2604                 if (ce->comp->compress_proto == proto)
2605                         return ce;
2606         }
2607         return NULL;
2608 }
2609
2610 /* Register a compressor */
2611 int
2612 ppp_register_compressor(struct compressor *cp)
2613 {
2614         struct compressor_entry *ce;
2615         int ret;
2616         spin_lock(&compressor_list_lock);
2617         ret = -EEXIST;
2618         if (find_comp_entry(cp->compress_proto))
2619                 goto out;
2620         ret = -ENOMEM;
2621         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2622         if (!ce)
2623                 goto out;
2624         ret = 0;
2625         ce->comp = cp;
2626         list_add(&ce->list, &compressor_list);
2627  out:
2628         spin_unlock(&compressor_list_lock);
2629         return ret;
2630 }
2631
2632 /* Unregister a compressor */
2633 void
2634 ppp_unregister_compressor(struct compressor *cp)
2635 {
2636         struct compressor_entry *ce;
2637
2638         spin_lock(&compressor_list_lock);
2639         ce = find_comp_entry(cp->compress_proto);
2640         if (ce && ce->comp == cp) {
2641                 list_del(&ce->list);
2642                 kfree(ce);
2643         }
2644         spin_unlock(&compressor_list_lock);
2645 }
2646
2647 /* Find a compressor. */
2648 static struct compressor *
2649 find_compressor(int type)
2650 {
2651         struct compressor_entry *ce;
2652         struct compressor *cp = NULL;
2653
2654         spin_lock(&compressor_list_lock);
2655         ce = find_comp_entry(type);
2656         if (ce) {
2657                 cp = ce->comp;
2658                 if (!try_module_get(cp->owner))
2659                         cp = NULL;
2660         }
2661         spin_unlock(&compressor_list_lock);
2662         return cp;
2663 }
2664
2665 /*
2666  * Miscelleneous stuff.
2667  */
2668
2669 static void
2670 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2671 {
2672         struct slcompress *vj = ppp->vj;
2673
2674         memset(st, 0, sizeof(*st));
2675         st->p.ppp_ipackets = ppp->stats64.rx_packets;
2676         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2677         st->p.ppp_ibytes = ppp->stats64.rx_bytes;
2678         st->p.ppp_opackets = ppp->stats64.tx_packets;
2679         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2680         st->p.ppp_obytes = ppp->stats64.tx_bytes;
2681         if (!vj)
2682                 return;
2683         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2684         st->vj.vjs_compressed = vj->sls_o_compressed;
2685         st->vj.vjs_searches = vj->sls_o_searches;
2686         st->vj.vjs_misses = vj->sls_o_misses;
2687         st->vj.vjs_errorin = vj->sls_i_error;
2688         st->vj.vjs_tossed = vj->sls_i_tossed;
2689         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2690         st->vj.vjs_compressedin = vj->sls_i_compressed;
2691 }
2692
2693 /*
2694  * Stuff for handling the lists of ppp units and channels
2695  * and for initialization.
2696  */
2697
2698 /*
2699  * Create a new ppp interface unit.  Fails if it can't allocate memory
2700  * or if there is already a unit with the requested number.
2701  * unit == -1 means allocate a new number.
2702  */
2703 static struct ppp *ppp_create_interface(struct net *net, int unit,
2704                                         struct file *file, int *retp)
2705 {
2706         struct ppp *ppp;
2707         struct ppp_net *pn;
2708         struct net_device *dev = NULL;
2709         int ret = -ENOMEM;
2710         int i;
2711
2712         dev = alloc_netdev(sizeof(struct ppp), "", NET_NAME_UNKNOWN,
2713                            ppp_setup);
2714         if (!dev)
2715                 goto out1;
2716
2717         pn = ppp_pernet(net);
2718
2719         ppp = netdev_priv(dev);
2720         ppp->dev = dev;
2721         ppp->mru = PPP_MRU;
2722         init_ppp_file(&ppp->file, INTERFACE);
2723         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2724         ppp->owner = file;
2725         for (i = 0; i < NUM_NP; ++i)
2726                 ppp->npmode[i] = NPMODE_PASS;
2727         INIT_LIST_HEAD(&ppp->channels);
2728         spin_lock_init(&ppp->rlock);
2729         spin_lock_init(&ppp->wlock);
2730 #ifdef CONFIG_PPP_MULTILINK
2731         ppp->minseq = -1;
2732         skb_queue_head_init(&ppp->mrq);
2733 #endif /* CONFIG_PPP_MULTILINK */
2734 #ifdef CONFIG_PPP_FILTER
2735         ppp->pass_filter = NULL;
2736         ppp->active_filter = NULL;
2737 #endif /* CONFIG_PPP_FILTER */
2738
2739         /*
2740          * drum roll: don't forget to set
2741          * the net device is belong to
2742          */
2743         dev_net_set(dev, net);
2744
2745         mutex_lock(&pn->all_ppp_mutex);
2746
2747         if (unit < 0) {
2748                 unit = unit_get(&pn->units_idr, ppp);
2749                 if (unit < 0) {
2750                         ret = unit;
2751                         goto out2;
2752                 }
2753         } else {
2754                 ret = -EEXIST;
2755                 if (unit_find(&pn->units_idr, unit))
2756                         goto out2; /* unit already exists */
2757                 /*
2758                  * if caller need a specified unit number
2759                  * lets try to satisfy him, otherwise --
2760                  * he should better ask us for new unit number
2761                  *
2762                  * NOTE: yes I know that returning EEXIST it's not
2763                  * fair but at least pppd will ask us to allocate
2764                  * new unit in this case so user is happy :)
2765                  */
2766                 unit = unit_set(&pn->units_idr, ppp, unit);
2767                 if (unit < 0)
2768                         goto out2;
2769         }
2770
2771         /* Initialize the new ppp unit */
2772         ppp->file.index = unit;
2773         sprintf(dev->name, "ppp%d", unit);
2774
2775         ret = register_netdev(dev);
2776         if (ret != 0) {
2777                 unit_put(&pn->units_idr, unit);
2778                 netdev_err(ppp->dev, "PPP: couldn't register device %s (%d)\n",
2779                            dev->name, ret);
2780                 goto out2;
2781         }
2782
2783         ppp->ppp_net = net;
2784
2785         atomic_inc(&ppp_unit_count);
2786         mutex_unlock(&pn->all_ppp_mutex);
2787
2788         *retp = 0;
2789         return ppp;
2790
2791 out2:
2792         mutex_unlock(&pn->all_ppp_mutex);
2793         free_netdev(dev);
2794 out1:
2795         *retp = ret;
2796         return NULL;
2797 }
2798
2799 /*
2800  * Initialize a ppp_file structure.
2801  */
2802 static void
2803 init_ppp_file(struct ppp_file *pf, int kind)
2804 {
2805         pf->kind = kind;
2806         skb_queue_head_init(&pf->xq);
2807         skb_queue_head_init(&pf->rq);
2808         atomic_set(&pf->refcnt, 1);
2809         init_waitqueue_head(&pf->rwait);
2810 }
2811
2812 /*
2813  * Free the memory used by a ppp unit.  This is only called once
2814  * there are no channels connected to the unit and no file structs
2815  * that reference the unit.
2816  */
2817 static void ppp_destroy_interface(struct ppp *ppp)
2818 {
2819         atomic_dec(&ppp_unit_count);
2820
2821         if (!ppp->file.dead || ppp->n_channels) {
2822                 /* "can't happen" */
2823                 netdev_err(ppp->dev, "ppp: destroying ppp struct %p "
2824                            "but dead=%d n_channels=%d !\n",
2825                            ppp, ppp->file.dead, ppp->n_channels);
2826                 return;
2827         }
2828
2829         ppp_ccp_closed(ppp);
2830         if (ppp->vj) {
2831                 slhc_free(ppp->vj);
2832                 ppp->vj = NULL;
2833         }
2834         skb_queue_purge(&ppp->file.xq);
2835         skb_queue_purge(&ppp->file.rq);
2836 #ifdef CONFIG_PPP_MULTILINK
2837         skb_queue_purge(&ppp->mrq);
2838 #endif /* CONFIG_PPP_MULTILINK */
2839 #ifdef CONFIG_PPP_FILTER
2840         if (ppp->pass_filter) {
2841                 bpf_prog_destroy(ppp->pass_filter);
2842                 ppp->pass_filter = NULL;
2843         }
2844
2845         if (ppp->active_filter) {
2846                 bpf_prog_destroy(ppp->active_filter);
2847                 ppp->active_filter = NULL;
2848         }
2849 #endif /* CONFIG_PPP_FILTER */
2850
2851         kfree_skb(ppp->xmit_pending);
2852
2853         free_netdev(ppp->dev);
2854 }
2855
2856 /*
2857  * Locate an existing ppp unit.
2858  * The caller should have locked the all_ppp_mutex.
2859  */
2860 static struct ppp *
2861 ppp_find_unit(struct ppp_net *pn, int unit)
2862 {
2863         return unit_find(&pn->units_idr, unit);
2864 }
2865
2866 /*
2867  * Locate an existing ppp channel.
2868  * The caller should have locked the all_channels_lock.
2869  * First we look in the new_channels list, then in the
2870  * all_channels list.  If found in the new_channels list,
2871  * we move it to the all_channels list.  This is for speed
2872  * when we have a lot of channels in use.
2873  */
2874 static struct channel *
2875 ppp_find_channel(struct ppp_net *pn, int unit)
2876 {
2877         struct channel *pch;
2878
2879         list_for_each_entry(pch, &pn->new_channels, list) {
2880                 if (pch->file.index == unit) {
2881                         list_move(&pch->list, &pn->all_channels);
2882                         return pch;
2883                 }
2884         }
2885
2886         list_for_each_entry(pch, &pn->all_channels, list) {
2887                 if (pch->file.index == unit)
2888                         return pch;
2889         }
2890
2891         return NULL;
2892 }
2893
2894 /*
2895  * Connect a PPP channel to a PPP interface unit.
2896  */
2897 static int
2898 ppp_connect_channel(struct channel *pch, int unit)
2899 {
2900         struct ppp *ppp;
2901         struct ppp_net *pn;
2902         int ret = -ENXIO;
2903         int hdrlen;
2904
2905         pn = ppp_pernet(pch->chan_net);
2906
2907         mutex_lock(&pn->all_ppp_mutex);
2908         ppp = ppp_find_unit(pn, unit);
2909         if (!ppp)
2910                 goto out;
2911         write_lock_bh(&pch->upl);
2912         ret = -EINVAL;
2913         if (pch->ppp)
2914                 goto outl;
2915
2916         ppp_lock(ppp);
2917         if (pch->file.hdrlen > ppp->file.hdrlen)
2918                 ppp->file.hdrlen = pch->file.hdrlen;
2919         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2920         if (hdrlen > ppp->dev->hard_header_len)
2921                 ppp->dev->hard_header_len = hdrlen;
2922         list_add_tail(&pch->clist, &ppp->channels);
2923         ++ppp->n_channels;
2924         pch->ppp = ppp;
2925         atomic_inc(&ppp->file.refcnt);
2926         ppp_unlock(ppp);
2927         ret = 0;
2928
2929  outl:
2930         write_unlock_bh(&pch->upl);
2931  out:
2932         mutex_unlock(&pn->all_ppp_mutex);
2933         return ret;
2934 }
2935
2936 /*
2937  * Disconnect a channel from its ppp unit.
2938  */
2939 static int
2940 ppp_disconnect_channel(struct channel *pch)
2941 {
2942         struct ppp *ppp;
2943         int err = -EINVAL;
2944
2945         write_lock_bh(&pch->upl);
2946         ppp = pch->ppp;
2947         pch->ppp = NULL;
2948         write_unlock_bh(&pch->upl);
2949         if (ppp) {
2950                 /* remove it from the ppp unit's list */
2951                 ppp_lock(ppp);
2952                 list_del(&pch->clist);
2953                 if (--ppp->n_channels == 0)
2954                         wake_up_interruptible(&ppp->file.rwait);
2955                 ppp_unlock(ppp);
2956                 if (atomic_dec_and_test(&ppp->file.refcnt))
2957                         ppp_destroy_interface(ppp);
2958                 err = 0;
2959         }
2960         return err;
2961 }
2962
2963 /*
2964  * Free up the resources used by a ppp channel.
2965  */
2966 static void ppp_destroy_channel(struct channel *pch)
2967 {
2968         atomic_dec(&channel_count);
2969
2970         if (!pch->file.dead) {
2971                 /* "can't happen" */
2972                 pr_err("ppp: destroying undead channel %p !\n", pch);
2973                 return;
2974         }
2975         skb_queue_purge(&pch->file.xq);
2976         skb_queue_purge(&pch->file.rq);
2977         kfree(pch);
2978 }
2979
2980 static void __exit ppp_cleanup(void)
2981 {
2982         /* should never happen */
2983         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2984                 pr_err("PPP: removing module but units remain!\n");
2985         unregister_chrdev(PPP_MAJOR, "ppp");
2986         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2987         class_destroy(ppp_class);
2988         unregister_pernet_device(&ppp_net_ops);
2989 }
2990
2991 /*
2992  * Units handling. Caller must protect concurrent access
2993  * by holding all_ppp_mutex
2994  */
2995
2996 /* associate pointer with specified number */
2997 static int unit_set(struct idr *p, void *ptr, int n)
2998 {
2999         int unit;
3000
3001         unit = idr_alloc(p, ptr, n, n + 1, GFP_KERNEL);
3002         if (unit == -ENOSPC)
3003                 unit = -EINVAL;
3004         return unit;
3005 }
3006
3007 /* get new free unit number and associate pointer with it */
3008 static int unit_get(struct idr *p, void *ptr)
3009 {
3010         return idr_alloc(p, ptr, 0, 0, GFP_KERNEL);
3011 }
3012
3013 /* put unit number back to a pool */
3014 static void unit_put(struct idr *p, int n)
3015 {
3016         idr_remove(p, n);
3017 }
3018
3019 /* get pointer associated with the number */
3020 static void *unit_find(struct idr *p, int n)
3021 {
3022         return idr_find(p, n);
3023 }
3024
3025 /* Module/initialization stuff */
3026
3027 module_init(ppp_init);
3028 module_exit(ppp_cleanup);
3029
3030 EXPORT_SYMBOL(ppp_register_net_channel);
3031 EXPORT_SYMBOL(ppp_register_channel);
3032 EXPORT_SYMBOL(ppp_unregister_channel);
3033 EXPORT_SYMBOL(ppp_channel_index);
3034 EXPORT_SYMBOL(ppp_unit_number);
3035 EXPORT_SYMBOL(ppp_dev_name);
3036 EXPORT_SYMBOL(ppp_input);
3037 EXPORT_SYMBOL(ppp_input_error);
3038 EXPORT_SYMBOL(ppp_output_wakeup);
3039 EXPORT_SYMBOL(ppp_register_compressor);
3040 EXPORT_SYMBOL(ppp_unregister_compressor);
3041 MODULE_LICENSE("GPL");
3042 MODULE_ALIAS_CHARDEV(PPP_MAJOR, 0);
3043 MODULE_ALIAS("devname:ppp");