package/system/mtd/src/wrg.c

   1 /*
   2  * wrg.c
   3  *
   4  * Copyright (C) 2005 Mike Baker
   5  * Copyright (C) 2008 Felix Fietkau <nbd@nbd.name>
   6  * Copyright (C) 2011-2012 Gabor Juhos <juhosg@openwrt.org>
   7  * Copyright (C) 2016 Stijn Tintel <stijn@linux-ipv6.be>
   8  * Copyright (C) 2017 George Hopkins <george-hopkins@null.net>
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  23  */
  24
  25 #include <byteswap.h>
  26 #include <endian.h>
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29 #include <stddef.h>
  30 #include <unistd.h>
  31 #include <fcntl.h>
  32 #include <sys/mman.h>
  33 #include <sys/stat.h>
  34 #include <string.h>
  35 #include <errno.h>
  36 #include <arpa/inet.h>
  37
  38 #include <sys/ioctl.h>
  39 #include <mtd/mtd-user.h>
  40 #include "mtd.h"
  41 #include "md5.h"
  42
  43 #if !defined(__BYTE_ORDER)
  44 #error "Unknown byte order"
  45 #endif
  46
  47 #if __BYTE_ORDER == __BIG_ENDIAN
  48 #define cpu_to_le32(x)  bswap_32(x)
  49 #define le32_to_cpu(x)  bswap_32(x)
  50 #elif __BYTE_ORDER == __LITTLE_ENDIAN
  51 #define cpu_to_le32(x)  (x)
  52 #define le32_to_cpu(x)  (x)
  53 #else
  54 #error "Unsupported endianness"
  55 #endif
  56
  57 #define WRG_MAGIC       0x20040220
  58
  59 struct wrg_header {
  60         char            signature[32];
  61         uint32_t        magic1;
  62         uint32_t        magic2;
  63         uint32_t        size;
  64         uint32_t        offset;
  65         char            devname[32];
  66         char            digest[16];
  67 } __attribute__ ((packed));
  68
  69 ssize_t pread(int fd, void *buf, size_t count, off_t offset);
  70 ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);
  71
  72 int
  73 wrg_fix_md5(struct wrg_header *shdr, int fd, size_t data_offset, size_t data_size)
  74 {
  75         char *buf;
  76         ssize_t res;
  77         MD5_CTX ctx;
  78         unsigned char digest[16];
  79         int i;
  80         int err = 0;
  81
  82         buf = malloc(data_size);
  83         if (!buf) {
  84                 err = -ENOMEM;
  85                 goto err_out;
  86         }
  87
  88         res = pread(fd, buf, data_size, data_offset);
  89         if (res != data_size) {
  90                 perror("pread");
  91                 err = -EIO;
  92                 goto err_free;
  93         }
  94
  95         MD5_Init(&ctx);
  96         MD5_Update(&ctx, (char *)&shdr->offset, sizeof(shdr->offset));
  97         MD5_Update(&ctx, (char *)&shdr->devname, sizeof(shdr->devname));
  98         MD5_Update(&ctx, buf, data_size);
  99         MD5_Final(digest, &ctx);
 100
 101         if (!memcmp(digest, shdr->digest, sizeof(digest))) {
 102                 if (quiet < 2)
 103                         fprintf(stderr, "the header is fixed already\n");
 104                 return -1;
 105         }
 106
 107         if (quiet < 2) {
 108                 fprintf(stderr, "new size: %u, new MD5: ", data_size);
 109                 for (i = 0; i < sizeof(digest); i++)
 110                         fprintf(stderr, "%02x", digest[i]);
 111
 112                 fprintf(stderr, "\n");
 113         }
 114
 115         /* update the size in the image */
 116         shdr->size = cpu_to_le32(data_size);
 117
 118         /* update the checksum in the image */
 119         memcpy(shdr->digest, digest, sizeof(digest));
 120
 121 err_free:
 122         free(buf);
 123 err_out:
 124         return err;
 125 }
 126
 127 int
 128 mtd_fixwrg(const char *mtd, size_t offset, size_t data_size)
 129 {
 130         int fd;
 131         char *first_block;
 132         ssize_t res;
 133         size_t block_offset;
 134         size_t data_offset;
 135         struct wrg_header *shdr;
 136
 137         if (quiet < 2)
 138                 fprintf(stderr, "Trying to fix WRG header in %s at 0x%x...\n",
 139                         mtd, offset);
 140
 141         block_offset = offset & ~(erasesize - 1);
 142         offset -= block_offset;
 143
 144         fd = mtd_check_open(mtd);
 145         if(fd < 0) {
 146                 fprintf(stderr, "Could not open mtd device: %s\n", mtd);
 147                 exit(1);
 148         }
 149
 150         if (block_offset + erasesize > mtdsize) {
 151                 fprintf(stderr, "Offset too large, device size 0x%x\n",
 152                         mtdsize);
 153                 exit(1);
 154         }
 155
 156         first_block = malloc(erasesize);
 157         if (!first_block) {
 158                 perror("malloc");
 159                 exit(1);
 160         }
 161
 162         res = pread(fd, first_block, erasesize, block_offset);
 163         if (res != erasesize) {
 164                 perror("pread");
 165                 exit(1);
 166         }
 167
 168         shdr = (struct wrg_header *)(first_block + offset);
 169         if (le32_to_cpu(shdr->magic1) != WRG_MAGIC) {
 170                 fprintf(stderr, "No WRG header found (%08x != %08x)\n",
 171                         le32_to_cpu(shdr->magic1), WRG_MAGIC);
 172                 exit(1);
 173         } else if (!le32_to_cpu(shdr->size)) {
 174                 fprintf(stderr, "WRG entity with empty image\n");
 175                 exit(1);
 176         }
 177
 178         data_offset = offset + sizeof(struct wrg_header);
 179         if (!data_size)
 180                 data_size = mtdsize - data_offset;
 181         if (data_size > le32_to_cpu(shdr->size))
 182                 data_size = le32_to_cpu(shdr->size);
 183         if (wrg_fix_md5(shdr, fd, data_offset, data_size))
 184                 goto out;
 185
 186         if (mtd_erase_block(fd, block_offset)) {
 187                 fprintf(stderr, "Can't erease block at 0x%x (%s)\n",
 188                         block_offset, strerror(errno));
 189                 exit(1);
 190         }
 191
 192         if (quiet < 2)
 193                 fprintf(stderr, "Rewriting block at 0x%x\n", block_offset);
 194
 195         if (pwrite(fd, first_block, erasesize, block_offset) != erasesize) {
 196                 fprintf(stderr, "Error writing block (%s)\n", strerror(errno));
 197                 exit(1);
 198         }
 199
 200         if (quiet < 2)
 201                 fprintf(stderr, "Done.\n");
 202
 203 out:
 204         close (fd);
 205         sync();
 206
 207         return 0;
 208 }