lib/decompress_unlzo.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * LZO decompressor for the Linux kernel. Code borrowed from the lzo
   4  * implementation by Markus Franz Xaver Johannes Oberhumer.
   5  *
   6  * Linux kernel adaptation:
   7  * Copyright (C) 2009
   8  * Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
   9  *
  10  * Original code:
  11  * Copyright (C) 1996-2005 Markus Franz Xaver Johannes Oberhumer
  12  * All Rights Reserved.
  13  *
  14  * Markus F.X.J. Oberhumer
  15  * <markus@oberhumer.com>
  16  * http://www.oberhumer.com/opensource/lzop/
  17  */
  18
  19 #ifdef STATIC
  20 #define PREBOOT
  21 #include "lzo/lzo1x_decompress_safe.c"
  22 #else
  23 #include <linux/decompress/unlzo.h>
  24 #endif
  25
  26 #include <linux/types.h>
  27 #include <linux/lzo.h>
  28 #include <linux/decompress/mm.h>
  29
  30 #include <linux/compiler.h>
  31 #include <linux/unaligned.h>
  32
  33 static const unsigned char lzop_magic[] = {
  34         0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a };
  35
  36 #define LZO_BLOCK_SIZE        (256*1024l)
  37 #define HEADER_HAS_FILTER      0x00000800L
  38 #define HEADER_SIZE_MIN       (9 + 7     + 4 + 8     + 1       + 4)
  39 #define HEADER_SIZE_MAX       (9 + 7 + 1 + 8 + 8 + 4 + 1 + 255 + 4)
  40
  41 STATIC inline long INIT parse_header(u8 *input, long *skip, long in_len)
  42 {
  43         int l;
  44         u8 *parse = input;
  45         u8 *end = input + in_len;
  46         u16 version;
  47
  48         /*
  49          * Check that there's enough input to possibly have a valid header.
  50          * Then it is possible to parse several fields until the minimum
  51          * size may have been used.
  52          */
  53         if (in_len < HEADER_SIZE_MIN)
  54                 return 0;
  55
  56         /* read magic: 9 first bits */
  57         for (l = 0; l < 9; l++) {
  58                 if (*parse++ != lzop_magic[l])
  59                         return 0;
  60         }
  61         /* get version (2bytes), skip library version (2),
  62          * 'need to be extracted' version (2) and
  63          * method (1) */
  64         version = get_unaligned_be16(parse);
  65         parse += 7;
  66         if (version >= 0x0940)
  67                 parse++;
  68         if (get_unaligned_be32(parse) & HEADER_HAS_FILTER)
  69                 parse += 8; /* flags + filter info */
  70         else
  71                 parse += 4; /* flags */
  72
  73         /*
  74          * At least mode, mtime_low, filename length, and checksum must
  75          * be left to be parsed. If also mtime_high is present, it's OK
  76          * because the next input buffer check is after reading the
  77          * filename length.
  78          */
  79         if (end - parse < 8 + 1 + 4)
  80                 return 0;
  81
  82         /* skip mode and mtime_low */
  83         parse += 8;
  84         if (version >= 0x0940)
  85                 parse += 4;     /* skip mtime_high */
  86
  87         l = *parse++;
  88         /* don't care about the file name, and skip checksum */
  89         if (end - parse < l + 4)
  90                 return 0;
  91         parse += l + 4;
  92
  93         *skip = parse - input;
  94         return 1;
  95 }
  96
  97 STATIC int INIT unlzo(u8 *input, long in_len,
  98                                 long (*fill)(void *, unsigned long),
  99                                 long (*flush)(void *, unsigned long),
 100                                 u8 *output, long *posp,
 101                                 void (*error) (char *x))
 102 {
 103         u8 r = 0;
 104         long skip = 0;
 105         u32 src_len, dst_len;
 106         size_t tmp;
 107         u8 *in_buf, *in_buf_save, *out_buf;
 108         int ret = -1;
 109
 110         if (output) {
 111                 out_buf = output;
 112         } else if (!flush) {
 113                 error("NULL output pointer and no flush function provided");
 114                 goto exit;
 115         } else {
 116                 out_buf = malloc(LZO_BLOCK_SIZE);
 117                 if (!out_buf) {
 118                         error("Could not allocate output buffer");
 119                         goto exit;
 120                 }
 121         }
 122
 123         if (input && fill) {
 124                 error("Both input pointer and fill function provided, don't know what to do");
 125                 goto exit_1;
 126         } else if (input) {
 127                 in_buf = input;
 128         } else if (!fill) {
 129                 error("NULL input pointer and missing fill function");
 130                 goto exit_1;
 131         } else {
 132                 in_buf = malloc(lzo1x_worst_compress(LZO_BLOCK_SIZE));
 133                 if (!in_buf) {
 134                         error("Could not allocate input buffer");
 135                         goto exit_1;
 136                 }
 137         }
 138         in_buf_save = in_buf;
 139
 140         if (posp)
 141                 *posp = 0;
 142
 143         if (fill) {
 144                 /*
 145                  * Start from in_buf + HEADER_SIZE_MAX to make it possible
 146                  * to use memcpy() to copy the unused data to the beginning
 147                  * of the buffer. This way memmove() isn't needed which
 148                  * is missing from pre-boot environments of most archs.
 149                  */
 150                 in_buf += HEADER_SIZE_MAX;
 151                 in_len = fill(in_buf, HEADER_SIZE_MAX);
 152         }
 153
 154         if (!parse_header(in_buf, &skip, in_len)) {
 155                 error("invalid header");
 156                 goto exit_2;
 157         }
 158         in_buf += skip;
 159         in_len -= skip;
 160
 161         if (fill) {
 162                 /* Move the unused data to the beginning of the buffer. */
 163                 memcpy(in_buf_save, in_buf, in_len);
 164                 in_buf = in_buf_save;
 165         }
 166
 167         if (posp)
 168                 *posp = skip;
 169
 170         for (;;) {
 171                 /* read uncompressed block size */
 172                 if (fill && in_len < 4) {
 173                         skip = fill(in_buf + in_len, 4 - in_len);
 174                         if (skip > 0)
 175                                 in_len += skip;
 176                 }
 177                 if (in_len < 4) {
 178                         error("file corrupted");
 179                         goto exit_2;
 180                 }
 181                 dst_len = get_unaligned_be32(in_buf);
 182                 in_buf += 4;
 183                 in_len -= 4;
 184
 185                 /* exit if last block */
 186                 if (dst_len == 0) {
 187                         if (posp)
 188                                 *posp += 4;
 189                         break;
 190                 }
 191
 192                 if (dst_len > LZO_BLOCK_SIZE) {
 193                         error("dest len longer than block size");
 194                         goto exit_2;
 195                 }
 196
 197                 /* read compressed block size, and skip block checksum info */
 198                 if (fill && in_len < 8) {
 199                         skip = fill(in_buf + in_len, 8 - in_len);
 200                         if (skip > 0)
 201                                 in_len += skip;
 202                 }
 203                 if (in_len < 8) {
 204                         error("file corrupted");
 205                         goto exit_2;
 206                 }
 207                 src_len = get_unaligned_be32(in_buf);
 208                 in_buf += 8;
 209                 in_len -= 8;
 210
 211                 if (src_len <= 0 || src_len > dst_len) {
 212                         error("file corrupted");
 213                         goto exit_2;
 214                 }
 215
 216                 /* decompress */
 217                 if (fill && in_len < src_len) {
 218                         skip = fill(in_buf + in_len, src_len - in_len);
 219                         if (skip > 0)
 220                                 in_len += skip;
 221                 }
 222                 if (in_len < src_len) {
 223                         error("file corrupted");
 224                         goto exit_2;
 225                 }
 226                 tmp = dst_len;
 227
 228                 /* When the input data is not compressed at all,
 229                  * lzo1x_decompress_safe will fail, so call memcpy()
 230                  * instead */
 231                 if (unlikely(dst_len == src_len))
 232                         memcpy(out_buf, in_buf, src_len);
 233                 else {
 234                         r = lzo1x_decompress_safe((u8 *) in_buf, src_len,
 235                                                 out_buf, &tmp);
 236
 237                         if (r != LZO_E_OK || dst_len != tmp) {
 238                                 error("Compressed data violation");
 239                                 goto exit_2;
 240                         }
 241                 }
 242
 243                 if (flush && flush(out_buf, dst_len) != dst_len)
 244                         goto exit_2;
 245                 if (output)
 246                         out_buf += dst_len;
 247                 if (posp)
 248                         *posp += src_len + 12;
 249
 250                 in_buf += src_len;
 251                 in_len -= src_len;
 252                 if (fill) {
 253                         /*
 254                          * If there happens to still be unused data left in
 255                          * in_buf, move it to the beginning of the buffer.
 256                          * Use a loop to avoid memmove() dependency.
 257                          */
 258                         if (in_len > 0)
 259                                 for (skip = 0; skip < in_len; ++skip)
 260                                         in_buf_save[skip] = in_buf[skip];
 261                         in_buf = in_buf_save;
 262                 }
 263         }
 264
 265         ret = 0;
 266 exit_2:
 267         if (!input)
 268                 free(in_buf_save);
 269 exit_1:
 270         if (!output)
 271                 free(out_buf);
 272 exit:
 273         return ret;
 274 }
 275
 276 #ifdef PREBOOT
 277 STATIC int INIT __decompress(unsigned char *buf, long len,
 278                            long (*fill)(void*, unsigned long),
 279                            long (*flush)(void*, unsigned long),
 280                            unsigned char *out_buf, long olen,
 281                            long *pos,
 282                            void (*error)(char *x))
 283 {
 284         return unlzo(buf, len, fill, flush, out_buf, pos, error);
 285 }
 286 #endif