net/ppp/ppp_deflate.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * ppp_deflate.c - interface the zlib procedures for Deflate compression
0004  * and decompression (as used by gzip) to the PPP code.
0005  *
0006  * Copyright 1994-1998 Paul Mackerras.
0007  */
0008
0009 #include <linux/module.h>
0010 #include <linux/slab.h>
0011 #include <linux/vmalloc.h>
0012 #include <linux/init.h>
0013 #include <linux/string.h>
0014
0015 #include <linux/ppp_defs.h>
0016 #include <linux/ppp-comp.h>
0017
0018 #include <linux/zlib.h>
0019 #include <asm/unaligned.h>
0020
0021 /*
0022  * State for a Deflate (de)compressor.
0023  */
0024 struct ppp_deflate_state {
0025     int     seqno;
0026     int     w_size;
0027     int     unit;
0028     int     mru;
0029     int     debug;
0030     z_stream    strm;
0031     struct compstat stats;
0032 };
0033
0034 #define DEFLATE_OVHD    2       /* Deflate overhead/packet */
0035
0036 static void *z_comp_alloc(unsigned char *options, int opt_len);
0037 static void *z_decomp_alloc(unsigned char *options, int opt_len);
0038 static void z_comp_free(void *state);
0039 static void z_decomp_free(void *state);
0040 static int  z_comp_init(void *state, unsigned char *options,
0041                  int opt_len,
0042                  int unit, int hdrlen, int debug);
0043 static int  z_decomp_init(void *state, unsigned char *options,
0044                    int opt_len,
0045                    int unit, int hdrlen, int mru, int debug);
0046 static int  z_compress(void *state, unsigned char *rptr,
0047                 unsigned char *obuf,
0048                 int isize, int osize);
0049 static void z_incomp(void *state, unsigned char *ibuf, int icnt);
0050 static int  z_decompress(void *state, unsigned char *ibuf,
0051                 int isize, unsigned char *obuf, int osize);
0052 static void z_comp_reset(void *state);
0053 static void z_decomp_reset(void *state);
0054 static void z_comp_stats(void *state, struct compstat *stats);
0055
0056 /**
0057  *  z_comp_free - free the memory used by a compressor
0058  *  @arg:   pointer to the private state for the compressor.
0059  */
0060 static void z_comp_free(void *arg)
0061 {
0062     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0063
0064     if (state) {
0065         zlib_deflateEnd(&state->strm);
0066         vfree(state->strm.workspace);
0067         kfree(state);
0068     }
0069 }
0070
0071 /**
0072  *  z_comp_alloc - allocate space for a compressor.
0073  *  @options: pointer to CCP option data
0074  *  @opt_len: length of the CCP option at @options.
0075  *
0076  *  The @options pointer points to the a buffer containing the
0077  *  CCP option data for the compression being negotiated.  It is
0078  *  formatted according to RFC1979, and describes the window
0079  *  size that the peer is requesting that we use in compressing
0080  *  data to be sent to it.
0081  *
0082  *  Returns the pointer to the private state for the compressor,
0083  *  or NULL if we could not allocate enough memory.
0084  */
0085 static void *z_comp_alloc(unsigned char *options, int opt_len)
0086 {
0087     struct ppp_deflate_state *state;
0088     int w_size;
0089
0090     if (opt_len != CILEN_DEFLATE ||
0091         (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
0092         options[1] != CILEN_DEFLATE ||
0093         DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
0094         options[3] != DEFLATE_CHK_SEQUENCE)
0095         return NULL;
0096     w_size = DEFLATE_SIZE(options[2]);
0097     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
0098         return NULL;
0099
0100     state = kzalloc(sizeof(*state),
0101                              GFP_KERNEL);
0102     if (state == NULL)
0103         return NULL;
0104
0105     state->strm.next_in   = NULL;
0106     state->w_size         = w_size;
0107     state->strm.workspace = vmalloc(zlib_deflate_workspacesize(-w_size, 8));
0108     if (state->strm.workspace == NULL)
0109         goto out_free;
0110
0111     if (zlib_deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION,
0112              DEFLATE_METHOD_VAL, -w_size, 8, Z_DEFAULT_STRATEGY)
0113         != Z_OK)
0114         goto out_free;
0115     return (void *) state;
0116
0117 out_free:
0118     z_comp_free(state);
0119     return NULL;
0120 }
0121
0122 /**
0123  *  z_comp_init - initialize a previously-allocated compressor.
0124  *  @arg:   pointer to the private state for the compressor
0125  *  @options: pointer to the CCP option data describing the
0126  *      compression that was negotiated with the peer
0127  *  @opt_len: length of the CCP option data at @options
0128  *  @unit:  PPP unit number for diagnostic messages
0129  *  @hdrlen: ignored (present for backwards compatibility)
0130  *  @debug: debug flag; if non-zero, debug messages are printed.
0131  *
0132  *  The CCP options described by @options must match the options
0133  *  specified when the compressor was allocated.  The compressor
0134  *  history is reset.  Returns 0 for failure (CCP options don't
0135  *  match) or 1 for success.
0136  */
0137 static int z_comp_init(void *arg, unsigned char *options, int opt_len,
0138                int unit, int hdrlen, int debug)
0139 {
0140     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0141
0142     if (opt_len < CILEN_DEFLATE ||
0143         (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
0144         options[1] != CILEN_DEFLATE ||
0145         DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
0146         DEFLATE_SIZE(options[2]) != state->w_size ||
0147         options[3] != DEFLATE_CHK_SEQUENCE)
0148         return 0;
0149
0150     state->seqno = 0;
0151     state->unit  = unit;
0152     state->debug = debug;
0153
0154     zlib_deflateReset(&state->strm);
0155
0156     return 1;
0157 }
0158
0159 /**
0160  *  z_comp_reset - reset a previously-allocated compressor.
0161  *  @arg:   pointer to private state for the compressor.
0162  *
0163  *  This clears the history for the compressor and makes it
0164  *  ready to start emitting a new compressed stream.
0165  */
0166 static void z_comp_reset(void *arg)
0167 {
0168     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0169
0170     state->seqno = 0;
0171     zlib_deflateReset(&state->strm);
0172 }
0173
0174 /**
0175  *  z_compress - compress a PPP packet with Deflate compression.
0176  *  @arg:   pointer to private state for the compressor
0177  *  @rptr:  uncompressed packet (input)
0178  *  @obuf:  compressed packet (output)
0179  *  @isize: size of uncompressed packet
0180  *  @osize: space available at @obuf
0181  *
0182  *  Returns the length of the compressed packet, or 0 if the
0183  *  packet is incompressible.
0184  */
0185 static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,
0186            int isize, int osize)
0187 {
0188     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0189     int r, proto, off, olen, oavail;
0190     unsigned char *wptr;
0191
0192     /*
0193      * Check that the protocol is in the range we handle.
0194      */
0195     proto = PPP_PROTOCOL(rptr);
0196     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
0197         return 0;
0198
0199     /* Don't generate compressed packets which are larger than
0200        the uncompressed packet. */
0201     if (osize > isize)
0202         osize = isize;
0203
0204     wptr = obuf;
0205
0206     /*
0207      * Copy over the PPP header and store the 2-byte sequence number.
0208      */
0209     wptr[0] = PPP_ADDRESS(rptr);
0210     wptr[1] = PPP_CONTROL(rptr);
0211     put_unaligned_be16(PPP_COMP, wptr + 2);
0212     wptr += PPP_HDRLEN;
0213     put_unaligned_be16(state->seqno, wptr);
0214     wptr += DEFLATE_OVHD;
0215     olen = PPP_HDRLEN + DEFLATE_OVHD;
0216     state->strm.next_out = wptr;
0217     state->strm.avail_out = oavail = osize - olen;
0218     ++state->seqno;
0219
0220     off = (proto > 0xff) ? 2 : 3;   /* skip 1st proto byte if 0 */
0221     rptr += off;
0222     state->strm.next_in = rptr;
0223     state->strm.avail_in = (isize - off);
0224
0225     for (;;) {
0226         r = zlib_deflate(&state->strm, Z_PACKET_FLUSH);
0227         if (r != Z_OK) {
0228             if (state->debug)
0229                 printk(KERN_ERR
0230                        "z_compress: deflate returned %d\n", r);
0231             break;
0232         }
0233         if (state->strm.avail_out == 0) {
0234             olen += oavail;
0235             state->strm.next_out = NULL;
0236             state->strm.avail_out = oavail = 1000000;
0237         } else {
0238             break;      /* all done */
0239         }
0240     }
0241     olen += oavail - state->strm.avail_out;
0242
0243     /*
0244      * See if we managed to reduce the size of the packet.
0245      */
0246     if (olen < isize && olen <= osize) {
0247         state->stats.comp_bytes += olen;
0248         state->stats.comp_packets++;
0249     } else {
0250         state->stats.inc_bytes += isize;
0251         state->stats.inc_packets++;
0252         olen = 0;
0253     }
0254     state->stats.unc_bytes += isize;
0255     state->stats.unc_packets++;
0256
0257     return olen;
0258 }
0259
0260 /**
0261  *  z_comp_stats - return compression statistics for a compressor
0262  *      or decompressor.
0263  *  @arg:   pointer to private space for the (de)compressor
0264  *  @stats: pointer to a struct compstat to receive the result.
0265  */
0266 static void z_comp_stats(void *arg, struct compstat *stats)
0267 {
0268     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0269
0270     *stats = state->stats;
0271 }
0272
0273 /**
0274  *  z_decomp_free - Free the memory used by a decompressor.
0275  *  @arg:   pointer to private space for the decompressor.
0276  */
0277 static void z_decomp_free(void *arg)
0278 {
0279     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0280
0281     if (state) {
0282         vfree(state->strm.workspace);
0283         kfree(state);
0284     }
0285 }
0286
0287 /**
0288  *  z_decomp_alloc - allocate space for a decompressor.
0289  *  @options: pointer to CCP option data
0290  *  @opt_len: length of the CCP option at @options.
0291  *
0292  *  The @options pointer points to the a buffer containing the
0293  *  CCP option data for the compression being negotiated.  It is
0294  *  formatted according to RFC1979, and describes the window
0295  *  size that we are requesting the peer to use in compressing
0296  *  data to be sent to us.
0297  *
0298  *  Returns the pointer to the private state for the decompressor,
0299  *  or NULL if we could not allocate enough memory.
0300  */
0301 static void *z_decomp_alloc(unsigned char *options, int opt_len)
0302 {
0303     struct ppp_deflate_state *state;
0304     int w_size;
0305
0306     if (opt_len != CILEN_DEFLATE ||
0307         (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
0308         options[1] != CILEN_DEFLATE ||
0309         DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
0310         options[3] != DEFLATE_CHK_SEQUENCE)
0311         return NULL;
0312     w_size = DEFLATE_SIZE(options[2]);
0313     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
0314         return NULL;
0315
0316     state = kzalloc(sizeof(*state), GFP_KERNEL);
0317     if (state == NULL)
0318         return NULL;
0319
0320     state->w_size         = w_size;
0321     state->strm.next_out  = NULL;
0322     state->strm.workspace = vmalloc(zlib_inflate_workspacesize());
0323     if (state->strm.workspace == NULL)
0324         goto out_free;
0325
0326     if (zlib_inflateInit2(&state->strm, -w_size) != Z_OK)
0327         goto out_free;
0328     return (void *) state;
0329
0330 out_free:
0331     z_decomp_free(state);
0332     return NULL;
0333 }
0334
0335 /**
0336  *  z_decomp_init - initialize a previously-allocated decompressor.
0337  *  @arg:   pointer to the private state for the decompressor
0338  *  @options: pointer to the CCP option data describing the
0339  *      compression that was negotiated with the peer
0340  *  @opt_len: length of the CCP option data at @options
0341  *  @unit:  PPP unit number for diagnostic messages
0342  *  @hdrlen: ignored (present for backwards compatibility)
0343  *  @mru:   maximum length of decompressed packets
0344  *  @debug: debug flag; if non-zero, debug messages are printed.
0345  *
0346  *  The CCP options described by @options must match the options
0347  *  specified when the decompressor was allocated.  The decompressor
0348  *  history is reset.  Returns 0 for failure (CCP options don't
0349  *  match) or 1 for success.
0350  */
0351 static int z_decomp_init(void *arg, unsigned char *options, int opt_len,
0352              int unit, int hdrlen, int mru, int debug)
0353 {
0354     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0355
0356     if (opt_len < CILEN_DEFLATE ||
0357         (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
0358         options[1] != CILEN_DEFLATE ||
0359         DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
0360         DEFLATE_SIZE(options[2]) != state->w_size ||
0361         options[3] != DEFLATE_CHK_SEQUENCE)
0362         return 0;
0363
0364     state->seqno = 0;
0365     state->unit  = unit;
0366     state->debug = debug;
0367     state->mru   = mru;
0368
0369     zlib_inflateReset(&state->strm);
0370
0371     return 1;
0372 }
0373
0374 /**
0375  *  z_decomp_reset - reset a previously-allocated decompressor.
0376  *  @arg:   pointer to private state for the decompressor.
0377  *
0378  *  This clears the history for the decompressor and makes it
0379  *  ready to receive a new compressed stream.
0380  */
0381 static void z_decomp_reset(void *arg)
0382 {
0383     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0384
0385     state->seqno = 0;
0386     zlib_inflateReset(&state->strm);
0387 }
0388
0389 /**
0390  *  z_decompress - decompress a Deflate-compressed packet.
0391  *  @arg:   pointer to private state for the decompressor
0392  *  @ibuf:  pointer to input (compressed) packet data
0393  *  @isize: length of input packet
0394  *  @obuf:  pointer to space for output (decompressed) packet
0395  *  @osize: amount of space available at @obuf
0396  *
0397  * Because of patent problems, we return DECOMP_ERROR for errors
0398  * found by inspecting the input data and for system problems, but
0399  * DECOMP_FATALERROR for any errors which could possibly be said to
0400  * be being detected "after" decompression.  For DECOMP_ERROR,
0401  * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
0402  * infringing a patent of Motorola's if we do, so we take CCP down
0403  * instead.
0404  *
0405  * Given that the frame has the correct sequence number and a good FCS,
0406  * errors such as invalid codes in the input most likely indicate a
0407  * bug, so we return DECOMP_FATALERROR for them in order to turn off
0408  * compression, even though they are detected by inspecting the input.
0409  */
0410 static int z_decompress(void *arg, unsigned char *ibuf, int isize,
0411          unsigned char *obuf, int osize)
0412 {
0413     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0414     int olen, seq, r;
0415     int decode_proto, overflow;
0416     unsigned char overflow_buf[1];
0417
0418     if (isize <= PPP_HDRLEN + DEFLATE_OVHD) {
0419         if (state->debug)
0420             printk(KERN_DEBUG "z_decompress%d: short pkt (%d)\n",
0421                    state->unit, isize);
0422         return DECOMP_ERROR;
0423     }
0424
0425     /* Check the sequence number. */
0426     seq = get_unaligned_be16(ibuf + PPP_HDRLEN);
0427     if (seq != (state->seqno & 0xffff)) {
0428         if (state->debug)
0429             printk(KERN_DEBUG "z_decompress%d: bad seq # %d, expected %d\n",
0430                    state->unit, seq, state->seqno & 0xffff);
0431         return DECOMP_ERROR;
0432     }
0433     ++state->seqno;
0434
0435     /*
0436      * Fill in the first part of the PPP header.  The protocol field
0437      * comes from the decompressed data.
0438      */
0439     obuf[0] = PPP_ADDRESS(ibuf);
0440     obuf[1] = PPP_CONTROL(ibuf);
0441     obuf[2] = 0;
0442
0443     /*
0444      * Set up to call inflate.  We set avail_out to 1 initially so we can
0445      * look at the first byte of the output and decide whether we have
0446      * a 1-byte or 2-byte protocol field.
0447      */
0448     state->strm.next_in = ibuf + PPP_HDRLEN + DEFLATE_OVHD;
0449     state->strm.avail_in = isize - (PPP_HDRLEN + DEFLATE_OVHD);
0450     state->strm.next_out = obuf + 3;
0451     state->strm.avail_out = 1;
0452     decode_proto = 1;
0453     overflow = 0;
0454
0455     /*
0456      * Call inflate, supplying more input or output as needed.
0457      */
0458     for (;;) {
0459         r = zlib_inflate(&state->strm, Z_PACKET_FLUSH);
0460         if (r != Z_OK) {
0461             if (state->debug)
0462                 printk(KERN_DEBUG "z_decompress%d: inflate returned %d (%s)\n",
0463                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
0464             return DECOMP_FATALERROR;
0465         }
0466         if (state->strm.avail_out != 0)
0467             break;      /* all done */
0468         if (decode_proto) {
0469             state->strm.avail_out = osize - PPP_HDRLEN;
0470             if ((obuf[3] & 1) == 0) {
0471                 /* 2-byte protocol field */
0472                 obuf[2] = obuf[3];
0473                 --state->strm.next_out;
0474                 ++state->strm.avail_out;
0475             }
0476             decode_proto = 0;
0477         } else if (!overflow) {
0478             /*
0479              * We've filled up the output buffer; the only way to
0480              * find out whether inflate has any more characters
0481              * left is to give it another byte of output space.
0482              */
0483             state->strm.next_out = overflow_buf;
0484             state->strm.avail_out = 1;
0485             overflow = 1;
0486         } else {
0487             if (state->debug)
0488                 printk(KERN_DEBUG "z_decompress%d: ran out of mru\n",
0489                        state->unit);
0490             return DECOMP_FATALERROR;
0491         }
0492     }
0493
0494     if (decode_proto) {
0495         if (state->debug)
0496             printk(KERN_DEBUG "z_decompress%d: didn't get proto\n",
0497                    state->unit);
0498         return DECOMP_ERROR;
0499     }
0500
0501     olen = osize + overflow - state->strm.avail_out;
0502     state->stats.unc_bytes += olen;
0503     state->stats.unc_packets++;
0504     state->stats.comp_bytes += isize;
0505     state->stats.comp_packets++;
0506
0507     return olen;
0508 }
0509
0510 /**
0511  *  z_incomp - add incompressible input data to the history.
0512  *  @arg:   pointer to private state for the decompressor
0513  *  @ibuf:  pointer to input packet data
0514  *  @icnt:  length of input data.
0515  */
0516 static void z_incomp(void *arg, unsigned char *ibuf, int icnt)
0517 {
0518     struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
0519     int proto, r;
0520
0521     /*
0522      * Check that the protocol is one we handle.
0523      */
0524     proto = PPP_PROTOCOL(ibuf);
0525     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
0526         return;
0527
0528     ++state->seqno;
0529
0530     /*
0531      * We start at the either the 1st or 2nd byte of the protocol field,
0532      * depending on whether the protocol value is compressible.
0533      */
0534     state->strm.next_in = ibuf + 3;
0535     state->strm.avail_in = icnt - 3;
0536     if (proto > 0xff) {
0537         --state->strm.next_in;
0538         ++state->strm.avail_in;
0539     }
0540
0541     r = zlib_inflateIncomp(&state->strm);
0542     if (r != Z_OK) {
0543         /* gak! */
0544         if (state->debug) {
0545             printk(KERN_DEBUG "z_incomp%d: inflateIncomp returned %d (%s)\n",
0546                    state->unit, r, (state->strm.msg? state->strm.msg: ""));
0547         }
0548         return;
0549     }
0550
0551     /*
0552      * Update stats.
0553      */
0554     state->stats.inc_bytes += icnt;
0555     state->stats.inc_packets++;
0556     state->stats.unc_bytes += icnt;
0557     state->stats.unc_packets++;
0558 }
0559
0560 /*************************************************************
0561  * Module interface table
0562  *************************************************************/
0563
0564 /* These are in ppp_generic.c */
0565 extern int  ppp_register_compressor   (struct compressor *cp);
0566 extern void ppp_unregister_compressor (struct compressor *cp);
0567
0568 /*
0569  * Procedures exported to if_ppp.c.
0570  */
0571 static struct compressor ppp_deflate = {
0572     .compress_proto =   CI_DEFLATE,
0573     .comp_alloc =       z_comp_alloc,
0574     .comp_free =        z_comp_free,
0575     .comp_init =        z_comp_init,
0576     .comp_reset =       z_comp_reset,
0577     .compress =     z_compress,
0578     .comp_stat =        z_comp_stats,
0579     .decomp_alloc =     z_decomp_alloc,
0580     .decomp_free =      z_decomp_free,
0581     .decomp_init =      z_decomp_init,
0582     .decomp_reset =     z_decomp_reset,
0583     .decompress =       z_decompress,
0584     .incomp =       z_incomp,
0585     .decomp_stat =      z_comp_stats,
0586     .owner =        THIS_MODULE
0587 };
0588
0589 static struct compressor ppp_deflate_draft = {
0590     .compress_proto =   CI_DEFLATE_DRAFT,
0591     .comp_alloc =       z_comp_alloc,
0592     .comp_free =        z_comp_free,
0593     .comp_init =        z_comp_init,
0594     .comp_reset =       z_comp_reset,
0595     .compress =     z_compress,
0596     .comp_stat =        z_comp_stats,
0597     .decomp_alloc =     z_decomp_alloc,
0598     .decomp_free =      z_decomp_free,
0599     .decomp_init =      z_decomp_init,
0600     .decomp_reset =     z_decomp_reset,
0601     .decompress =       z_decompress,
0602     .incomp =       z_incomp,
0603     .decomp_stat =      z_comp_stats,
0604     .owner =        THIS_MODULE
0605 };
0606
0607 static int __init deflate_init(void)
0608 {
0609     int rc;
0610
0611     rc = ppp_register_compressor(&ppp_deflate);
0612     if (rc)
0613         return rc;
0614
0615     rc = ppp_register_compressor(&ppp_deflate_draft);
0616     if (rc) {
0617         ppp_unregister_compressor(&ppp_deflate);
0618         return rc;
0619     }
0620
0621     pr_info("PPP Deflate Compression module registered\n");
0622     return 0;
0623 }
0624
0625 static void __exit deflate_cleanup(void)
0626 {
0627     ppp_unregister_compressor(&ppp_deflate);
0628     ppp_unregister_compressor(&ppp_deflate_draft);
0629 }
0630
0631 module_init(deflate_init);
0632 module_exit(deflate_cleanup);
0633 MODULE_LICENSE("Dual BSD/GPL");
0634 MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE));
0635 MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE_DRAFT));