// SPDX-License-Identifier: GPL-2.0-only
/*
* ppp_deflate.c - interface the zlib procedures for Deflate compression
* and decompression (as used by gzip) to the PPP code.
*
* Copyright 1994-1998 Paul Mackerras.
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/ppp_defs.h>
#include <linux/ppp-comp.h>
#include <linux/zlib.h>
#include <linux/unaligned.h>
/*
* State for a Deflate (de)compressor.
*/
struct ppp_deflate_state {
int seqno;
int w_size;
int unit;
int mru;
int debug;
z_stream strm;
struct compstat stats;
};
#define DEFLATE_OVHD 2 /* Deflate overhead/packet */
static void *z_comp_alloc(unsigned char *options, int opt_len);
static void *z_decomp_alloc(unsigned char *options, int opt_len);
static void z_comp_free(void *state);
static void z_decomp_free(void *state);
static int z_comp_init(void *state, unsigned char *options,
int opt_len,
int unit, int hdrlen, int debug);
static int z_decomp_init(void *state, unsigned char *options,
int opt_len,
int unit, int hdrlen, int mru, int debug);
static int z_compress(void *state, unsigned char *rptr,
unsigned char *obuf,
int isize, int osize);
static void z_incomp(void *state, unsigned char *ibuf, int icnt);
static int z_decompress(void *state, unsigned char *ibuf,
int isize, unsigned char *obuf, int osize);
static void z_comp_reset(void *state);
static void z_decomp_reset(void *state);
static void z_comp_stats(void *state, struct compstat *stats);
/**
* z_comp_free - free the memory used by a compressor
* @arg: pointer to the private state for the compressor.
*/
static void z_comp_free(void *arg)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
if (state) {
zlib_deflateEnd(&state->strm);
vfree(state->strm.workspace);
kfree(state);
}
}
/**
* z_comp_alloc - allocate space for a compressor.
* @options: pointer to CCP option data
* @opt_len: length of the CCP option at @options.
*
* The @options pointer points to the a buffer containing the
* CCP option data for the compression being negotiated. It is
* formatted according to RFC1979, and describes the window
* size that the peer is requesting that we use in compressing
* data to be sent to it.
*
* Returns the pointer to the private state for the compressor,
* or NULL if we could not allocate enough memory.
*/
static void *z_comp_alloc(unsigned char *options, int opt_len)
{
struct ppp_deflate_state *state;
int w_size;
if (opt_len != CILEN_DEFLATE ||
(options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
options[1] != CILEN_DEFLATE ||
DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
options[3] != DEFLATE_CHK_SEQUENCE)
return NULL;
w_size = DEFLATE_SIZE(options[2]);
if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
return NULL;
state = kzalloc(sizeof(*state),
GFP_KERNEL);
if (state == NULL)
return NULL;
state->strm.next_in = NULL;
state->w_size = w_size;
state->strm.workspace = vmalloc(zlib_deflate_workspacesize(-w_size, 8));
if (state->strm.workspace == NULL)
goto out_free;
if (zlib_deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION,
DEFLATE_METHOD_VAL, -w_size, 8, Z_DEFAULT_STRATEGY)
!= Z_OK)
goto out_free;
return (void *) state;
out_free:
z_comp_free(state);
return NULL;
}
/**
* z_comp_init - initialize a previously-allocated compressor.
* @arg: pointer to the private state for the compressor
* @options: pointer to the CCP option data describing the
* compression that was negotiated with the peer
* @opt_len: length of the CCP option data at @options
* @unit: PPP unit number for diagnostic messages
* @hdrlen: ignored (present for backwards compatibility)
* @debug: debug flag; if non-zero, debug messages are printed.
*
* The CCP options described by @options must match the options
* specified when the compressor was allocated. The compressor
* history is reset. Returns 0 for failure (CCP options don't
* match) or 1 for success.
*/
static int z_comp_init(void *arg, unsigned char *options, int opt_len,
int unit, int hdrlen, int debug)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
if (opt_len < CILEN_DEFLATE ||
(options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
options[1] != CILEN_DEFLATE ||
DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
DEFLATE_SIZE(options[2]) != state->w_size ||
options[3] != DEFLATE_CHK_SEQUENCE)
return 0;
state->seqno = 0;
state->unit = unit;
state->debug = debug;
zlib_deflateReset(&state->strm);
return 1;
}
/**
* z_comp_reset - reset a previously-allocated compressor.
* @arg: pointer to private state for the compressor.
*
* This clears the history for the compressor and makes it
* ready to start emitting a new compressed stream.
*/
static void z_comp_reset(void *arg)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
state->seqno = 0;
zlib_deflateReset(&state->strm);
}
/**
* z_compress - compress a PPP packet with Deflate compression.
* @arg: pointer to private state for the compressor
* @rptr: uncompressed packet (input)
* @obuf: compressed packet (output)
* @isize: size of uncompressed packet
* @osize: space available at @obuf
*
* Returns the length of the compressed packet, or 0 if the
* packet is incompressible.
*/
static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,
int isize, int osize)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
int r, proto, off, olen, oavail;
unsigned char *wptr;
/*
* Check that the protocol is in the range we handle.
*/
proto = PPP_PROTOCOL(rptr);
if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
return 0;
/* Don't generate compressed packets which are larger than
the uncompressed packet. */
if (osize > isize)
osize = isize;
wptr = obuf;
/*
* Copy over the PPP header and store the 2-byte sequence number.
*/
wptr[0] = PPP_ADDRESS(rptr);
wptr[1] = PPP_CONTROL(rptr);
put_unaligned_be16(PPP_COMP, wptr + 2);
wptr += PPP_HDRLEN;
put_unaligned_be16(state->seqno, wptr);
wptr += DEFLATE_OVHD;
olen = PPP_HDRLEN + DEFLATE_OVHD;
state->strm.next_out = wptr;
state->strm.avail_out = oavail = osize - olen;
++state->seqno;
off = (proto > 0xff) ? 2 : 3; /* skip 1st proto byte if 0 */
rptr += off;
state->strm.next_in = rptr;
state->strm.avail_in = (isize - off);
for (;;) {
r = zlib_deflate(&state->strm, Z_PACKET_FLUSH);
if (r != Z_OK) {
if (state->debug)
printk(KERN_ERR
"z_compress: deflate returned %d\n", r);
break;
}
if (state->strm.avail_out == 0) {
olen += oavail;
state->strm.next_out = NULL;
state->strm.avail_out = oavail = 1000000;
} else {
break; /* all done */
}
}
olen += oavail - state->strm.avail_out;
/*
* See if we managed to reduce the size of the packet.
*/
if (olen < isize && olen <= osize) {
state->stats.comp_bytes += olen;
state->stats.comp_packets++;
} else {
state->stats.inc_bytes += isize;
state->stats.inc_packets++;
olen = 0;
}
state->stats.unc_bytes += isize;
state->stats.unc_packets++;
return olen;
}
/**
* z_comp_stats - return compression statistics for a compressor
* or decompressor.
* @arg: pointer to private space for the (de)compressor
* @stats: pointer to a struct compstat to receive the result.
*/
static void z_comp_stats(void *arg, struct compstat *stats)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
*stats = state->stats;
}
/**
* z_decomp_free - Free the memory used by a decompressor.
* @arg: pointer to private space for the decompressor.
*/
static void z_decomp_free(void *arg)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
if (state) {
vfree(state->strm.workspace);
kfree(state);
}
}
/**
* z_decomp_alloc - allocate space for a decompressor.
* @options: pointer to CCP option data
* @opt_len: length of the CCP option at @options.
*
* The @options pointer points to the a buffer containing the
* CCP option data for the compression being negotiated. It is
* formatted according to RFC1979, and describes the window
* size that we are requesting the peer to use in compressing
* data to be sent to us.
*
* Returns the pointer to the private state for the decompressor,
* or NULL if we could not allocate enough memory.
*/
static void *z_decomp_alloc(unsigned char *options, int opt_len)
{
struct ppp_deflate_state *state;
int w_size;
if (opt_len != CILEN_DEFLATE ||
(options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
options[1] != CILEN_DEFLATE ||
DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
options[3] != DEFLATE_CHK_SEQUENCE)
return NULL;
w_size = DEFLATE_SIZE(options[2]);
if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
return NULL;
state = kzalloc(sizeof(*state), GFP_KERNEL);
if (state == NULL)
return NULL;
state->w_size = w_size;
state->strm.next_out = NULL;
state->strm.workspace = vmalloc(zlib_inflate_workspacesize());
if (state->strm.workspace == NULL)
goto out_free;
if (zlib_inflateInit2(&state->strm, -w_size) != Z_OK)
goto out_free;
return (void *) state;
out_free:
z_decomp_free(state);
return NULL;
}
/**
* z_decomp_init - initialize a previously-allocated decompressor.
* @arg: pointer to the private state for the decompressor
* @options: pointer to the CCP option data describing the
* compression that was negotiated with the peer
* @opt_len: length of the CCP option data at @options
* @unit: PPP unit number for diagnostic messages
* @hdrlen: ignored (present for backwards compatibility)
* @mru: maximum length of decompressed packets
* @debug: debug flag; if non-zero, debug messages are printed.
*
* The CCP options described by @options must match the options
* specified when the decompressor was allocated. The decompressor
* history is reset. Returns 0 for failure (CCP options don't
* match) or 1 for success.
*/
static int z_decomp_init(void *arg, unsigned char *options, int opt_len,
int unit, int hdrlen, int mru, int debug)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
if (opt_len < CILEN_DEFLATE ||
(options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
options[1] != CILEN_DEFLATE ||
DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
DEFLATE_SIZE(options[2]) != state->w_size ||
options[3] != DEFLATE_CHK_SEQUENCE)
return 0;
state->seqno = 0;
state->unit = unit;
state->debug = debug;
state->mru = mru;
zlib_inflateReset(&state->strm);
return 1;
}
/**
* z_decomp_reset - reset a previously-allocated decompressor.
* @arg: pointer to private state for the decompressor.
*
* This clears the history for the decompressor and makes it
* ready to receive a new compressed stream.
*/
static void z_decomp_reset(void *arg)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
state->seqno = 0;
zlib_inflateReset(&state->strm);
}
/**
* z_decompress - decompress a Deflate-compressed packet.
* @arg: pointer to private state for the decompressor
* @ibuf: pointer to input (compressed) packet data
* @isize: length of input packet
* @obuf: pointer to space for output (decompressed) packet
* @osize: amount of space available at @obuf
*
* Because of patent problems, we return DECOMP_ERROR for errors
* found by inspecting the input data and for system problems, but
* DECOMP_FATALERROR for any errors which could possibly be said to
* be being detected "after" decompression. For DECOMP_ERROR,
* we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
* infringing a patent of Motorola's if we do, so we take CCP down
* instead.
*
* Given that the frame has the correct sequence number and a good FCS,
* errors such as invalid codes in the input most likely indicate a
* bug, so we return DECOMP_FATALERROR for them in order to turn off
* compression, even though they are detected by inspecting the input.
*/
static int z_decompress(void *arg, unsigned char *ibuf, int isize,
unsigned char *obuf, int osize)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
int olen, seq, r;
int decode_proto, overflow;
unsigned char overflow_buf[1];
if (isize <= PPP_HDRLEN + DEFLATE_OVHD) {
if (state->debug)
printk(KERN_DEBUG "z_decompress%d: short pkt (%d)\n",
state->unit, isize);
return DECOMP_ERROR;
}
/* Check the sequence number. */
seq = get_unaligned_be16(ibuf + PPP_HDRLEN);
if (seq != (state->seqno & 0xffff)) {
if (state->debug)
printk(KERN_DEBUG "z_decompress%d: bad seq # %d, expected %d\n",
state->unit, seq, state->seqno & 0xffff);
return DECOMP_ERROR;
}
++state->seqno;
/*
* Fill in the first part of the PPP header. The protocol field
* comes from the decompressed data.
*/
obuf[0] = PPP_ADDRESS(ibuf);
obuf[1] = PPP_CONTROL(ibuf);
obuf[2] = 0;
/*
* Set up to call inflate. We set avail_out to 1 initially so we can
* look at the first byte of the output and decide whether we have
* a 1-byte or 2-byte protocol field.
*/
state->strm.next_in = ibuf + PPP_HDRLEN + DEFLATE_OVHD;
state->strm.avail_in = isize - (PPP_HDRLEN + DEFLATE_OVHD);
state->strm.next_out = obuf + 3;
state->strm.avail_out = 1;
decode_proto = 1;
overflow = 0;
/*
* Call inflate, supplying more input or output as needed.
*/
for (;;) {
r = zlib_inflate(&state->strm, Z_PACKET_FLUSH);
if (r != Z_OK) {
if (state->debug)
printk(KERN_DEBUG "z_decompress%d: inflate returned %d (%s)\n",
state->unit, r, (state->strm.msg? state->strm.msg: ""));
return DECOMP_FATALERROR;
}
if (state->strm.avail_out != 0)
break; /* all done */
if (decode_proto) {
state->strm.avail_out = osize - PPP_HDRLEN;
if ((obuf[3] & 1) == 0) {
/* 2-byte protocol field */
obuf[2] = obuf[3];
--state->strm.next_out;
++state->strm.avail_out;
}
decode_proto = 0;
} else if (!overflow) {
/*
* We've filled up the output buffer; the only way to
* find out whether inflate has any more characters
* left is to give it another byte of output space.
*/
state->strm.next_out = overflow_buf;
state->strm.avail_out = 1;
overflow = 1;
} else {
if (state->debug)
printk(KERN_DEBUG "z_decompress%d: ran out of mru\n",
state->unit);
return DECOMP_FATALERROR;
}
}
if (decode_proto) {
if (state->debug)
printk(KERN_DEBUG "z_decompress%d: didn't get proto\n",
state->unit);
return DECOMP_ERROR;
}
olen = osize + overflow - state->strm.avail_out;
state->stats.unc_bytes += olen;
state->stats.unc_packets++;
state->stats.comp_bytes += isize;
state->stats.comp_packets++;
return olen;
}
/**
* z_incomp - add incompressible input data to the history.
* @arg: pointer to private state for the decompressor
* @ibuf: pointer to input packet data
* @icnt: length of input data.
*/
static void z_incomp(void *arg, unsigned char *ibuf, int icnt)
{
struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
int proto, r;
/*
* Check that the protocol is one we handle.
*/
proto = PPP_PROTOCOL(ibuf);
if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
return;
++state->seqno;
/*
* We start at the either the 1st or 2nd byte of the protocol field,
* depending on whether the protocol value is compressible.
*/
state->strm.next_in = ibuf + 3;
state->strm.avail_in = icnt - 3;
if (proto > 0xff) {
--state->strm.next_in;
++state->strm.avail_in;
}
r = zlib_inflateIncomp(&state->strm);
if (r != Z_OK) {
/* gak! */
if (state->debug) {
printk(KERN_DEBUG "z_incomp%d: inflateIncomp returned %d (%s)\n",
state->unit, r, (state->strm.msg? state->strm.msg: ""));
}
return;
}
/*
* Update stats.
*/
state->stats.inc_bytes += icnt;
state->stats.inc_packets++;
state->stats.unc_bytes += icnt;
state->stats.unc_packets++;
}
/*************************************************************
* Module interface table
*************************************************************/
/* These are in ppp_generic.c */
extern int ppp_register_compressor (struct compressor *cp);
extern void ppp_unregister_compressor (struct compressor *cp);
/*
* Procedures exported to if_ppp.c.
*/
static struct compressor ppp_deflate = {
.compress_proto = CI_DEFLATE,
.comp_alloc = z_comp_alloc,
.comp_free = z_comp_free,
.comp_init = z_comp_init,
.comp_reset = z_comp_reset,
.compress = z_compress,
.comp_stat = z_comp_stats,
.decomp_alloc = z_decomp_alloc,
.decomp_free = z_decomp_free,
.decomp_init = z_decomp_init,
.decomp_reset = z_decomp_reset,
.decompress = z_decompress,
.incomp = z_incomp,
.decomp_stat = z_comp_stats,
.owner = THIS_MODULE
};
static struct compressor ppp_deflate_draft = {
.compress_proto = CI_DEFLATE_DRAFT,
.comp_alloc = z_comp_alloc,
.comp_free = z_comp_free,
.comp_init = z_comp_init,
.comp_reset = z_comp_reset,
.compress = z_compress,
.comp_stat = z_comp_stats,
.decomp_alloc = z_decomp_alloc,
.decomp_free = z_decomp_free,
.decomp_init = z_decomp_init,
.decomp_reset = z_decomp_reset,
.decompress = z_decompress,
.incomp = z_incomp,
.decomp_stat = z_comp_stats,
.owner = THIS_MODULE
};
static int __init deflate_init(void)
{
int rc;
rc = ppp_register_compressor(&ppp_deflate);
if (rc)
return rc;
rc = ppp_register_compressor(&ppp_deflate_draft);
if (rc) {
ppp_unregister_compressor(&ppp_deflate);
return rc;
}
pr_info("PPP Deflate Compression module registered\n");
return 0;
}
static void __exit deflate_cleanup(void)
{
ppp_unregister_compressor(&ppp_deflate);
ppp_unregister_compressor(&ppp_deflate_draft);
}
module_init(deflate_init);
module_exit(deflate_cleanup);
MODULE_DESCRIPTION("PPP Deflate compression module");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE));
MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE_DRAFT));
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