tools/firmware-utils/src/mkrasimage.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * --- ZyXEL header format ---
   4  * Original Version by Benjamin Berg <benjamin@sipsolutions.net>
   5  * C implementation based on generation-script by Christian Lamparter <chunkeey@gmail.com>
   6  *
   7  * The firmware image prefixed with a header (which is written into the MTD device).
   8  * The header is one erase block (~64KiB) in size, but the checksum only convers the
   9  * first 2KiB. Padding is 0xff. All integers are in big-endian.
  10  *
  11  * The checksum is always a 16-Bit System V checksum (sum -s) stored in a 32-Bit integer.
  12  *
  13  *   4 bytes:  checksum of the rootfs image
  14  *   4 bytes:  length of the contained rootfs image file (big endian)
  15  *  32 bytes:  Firmware Version string (NUL terminated, 0xff padded)
  16  *   4 bytes:  checksum over the header partition (big endian - see below)
  17  *  64 bytes:  Model (e.g. "NBG6617", NUL termiated, 0xff padded)
  18  *   4 bytes:  checksum of the kernel partition
  19  *   4 bytes:  length of the contained kernel image file (big endian)
  20  *      rest:  0xff padding (To erase block size)
  21  *
  22  * The kernel partition checksum and length is not used for every device.
  23  * If it's notused, pad those 8 bytes with 0xFF.
  24  *
  25  * The checksums are calculated by adding up all bytes and if a 16bit
  26  * overflow occurs, one is added and the sum is masked to 16 bit:
  27  *   csum = csum + databyte; if (csum > 0xffff) { csum += 1; csum &= 0xffff };
  28  * Should the file have an odd number of bytes then the byte len-0x800 is
  29  * used additionally.
  30  *
  31  * The checksum for the header is calculated over the first 2048 bytes with
  32  * the rootfs image checksum as the placeholder during calculation.
  33  */
  34 #include <fcntl.h>
  35 #include <getopt.h>
  36 #include <libgen.h>
  37 #include <stdio.h>
  38 #include <string.h>
  39 #include <stdlib.h>
  40 #include <unistd.h>
  41
  42 #include <sys/mman.h>
  43 #include <sys/stat.h>
  44
  45 #include <arpa/inet.h>
  46
  47 #define VERSION_STRING_LEN 31
  48 #define ROOTFS_HEADER_LEN 40
  49
  50 #define KERNEL_HEADER_LEN 8
  51
  52 #define BOARD_NAME_LEN 64
  53 #define BOARD_HEADER_LEN 68
  54
  55 #define HEADER_PARTITION_CALC_LENGTH 2048
  56 #define HEADER_PARTITION_LENGTH 0x10000
  57
  58 struct file_info {
  59     char *name;    /* name of the file */
  60     char *data;    /* file content */
  61     size_t size;   /* length of the file */
  62 };
  63
  64 static char *progname;
  65
  66 static char *board_name = 0;
  67 static char *version_name = 0;
  68 static unsigned int rootfs_size = 0;
  69 static unsigned int header_length = HEADER_PARTITION_LENGTH;
  70
  71 static struct file_info kernel = { NULL, NULL, 0 };
  72 static struct file_info rootfs = { NULL, NULL, 0 };
  73 static struct file_info rootfs_out = { NULL, NULL, 0 };
  74 static struct file_info out = { NULL, NULL, 0 };
  75
  76 #define ERR(fmt, ...) do { \
  77     fprintf(stderr, "[%s] *** error: " fmt "\n", \
  78             progname, ## __VA_ARGS__ ); \
  79 } while (0)
  80
  81 void map_file(struct file_info *finfo)
  82 {
  83     struct stat file_stat = {0};
  84     int fd;
  85
  86     fd = open(finfo->name, O_RDONLY, (mode_t)0600);
  87     if (fd == -1) {
  88         ERR("Error while opening file %s.", finfo->name);
  89         exit(EXIT_FAILURE);
  90     }
  91
  92     if (fstat(fd, &file_stat) == -1) {
  93         ERR("Error getting file size for %s.", finfo->name);
  94         exit(EXIT_FAILURE);
  95     }
  96
  97     finfo->size = file_stat.st_size;
  98     finfo->data = mmap(0, finfo->size, PROT_READ, MAP_SHARED, fd, 0);
  99
 100     if (finfo->data == MAP_FAILED) {
 101         ERR("Error mapping file %s.", finfo->name);
 102         exit(EXIT_FAILURE);
 103     }
 104
 105     close(fd);
 106 }
 107
 108 void unmap_file(struct file_info *finfo)
 109 {
 110     if(munmap(finfo->data, finfo->size) == -1) {
 111         ERR("Error unmapping file %s.", finfo->name);
 112         exit(EXIT_FAILURE);
 113     }
 114 }
 115
 116 void write_file(struct file_info *finfo)
 117 {
 118     FILE *fout = fopen(finfo->name, "w");
 119
 120     fwrite(finfo->data, finfo->size, 1, fout);
 121
 122     if (ferror(fout)) {
 123         ERR("Wanted to write, but something went wrong.");
 124         exit(EXIT_FAILURE);
 125     }
 126
 127     fclose(fout);
 128 }
 129
 130 void usage(int status)
 131 {
 132     FILE *stream = (status != EXIT_SUCCESS) ? stderr : stdout;
 133
 134     fprintf(stream, "Usage: %s [OPTIONS...]\n", progname);
 135     fprintf(stream,
 136             "\n"
 137             "Options:\n"
 138             "  -k <kernel>     path for kernel image\n"
 139             "  -r <rootfs>     path for rootfs image\n"
 140             "  -s <rfssize>    size of output rootfs\n"
 141             "  -v <version>    version string\n"
 142             "  -b <boardname>  name of board to generate image for\n"
 143             "  -o <out_name>   name of output image\n"
 144             "  -l <hdr_length> length of header, default 65536\n"
 145             "  -h              show this screen\n"
 146     );
 147
 148     exit(status);
 149 }
 150
 151 static int sysv_chksm(const unsigned char *data, int size)
 152 {
 153     int r;
 154     int checksum;
 155     unsigned int s = 0; /* The sum of all the input bytes, modulo (UINT_MAX + 1).  */
 156
 157
 158     for (int i = 0; i < size; i++) {
 159         s += data[i];
 160     }
 161
 162     r = (s & 0xffff) + ((s & 0xffffffff) >> 16);
 163     checksum = (r & 0xffff) + (r >> 16);
 164
 165     return checksum;
 166 }
 167
 168 static int zyxel_chksm(const unsigned char *data, int size)
 169 {
 170      return htonl(sysv_chksm(data, size));
 171 }
 172
 173 char *generate_rootfs_header(struct file_info filesystem, char *version)
 174 {
 175     size_t version_string_length;
 176     unsigned int chksm, size;
 177     char *rootfs_header;
 178     size_t ptr = 0;
 179
 180     rootfs_header = malloc(ROOTFS_HEADER_LEN);
 181     if (!rootfs_header) {
 182         ERR("Couldn't allocate memory for rootfs header!");
 183         exit(EXIT_FAILURE);
 184     }
 185
 186     /* Prepare padding for firmware-version string here */
 187     memset(rootfs_header, 0xff, ROOTFS_HEADER_LEN);
 188
 189     chksm = zyxel_chksm((const unsigned char *)filesystem.data, filesystem.size);
 190     size = htonl(filesystem.size);
 191
 192     /* 4 bytes:  checksum of the rootfs image */
 193     memcpy(rootfs_header + ptr, &chksm, 4);
 194     ptr += 4;
 195
 196     /* 4 bytes:  length of the contained rootfs image file (big endian) */
 197     memcpy(rootfs_header + ptr, &size, 4);
 198     ptr += 4;
 199
 200     /* 32 bytes:  Firmware Version string (NUL terminated, 0xff padded) */
 201     version_string_length = strlen(version) <= VERSION_STRING_LEN ? strlen(version) : VERSION_STRING_LEN;
 202     memcpy(rootfs_header + ptr, version, version_string_length);
 203     ptr += version_string_length;
 204     /* Add null-terminator */
 205     rootfs_header[ptr] = 0x0;
 206
 207     return rootfs_header;
 208 }
 209
 210 char *generate_kernel_header(struct file_info kernel)
 211 {
 212     unsigned int chksm, size;
 213     char *kernel_header;
 214     size_t ptr = 0;
 215
 216     kernel_header = malloc(KERNEL_HEADER_LEN);
 217     if (!kernel_header) {
 218         ERR("Couldn't allocate memory for kernel header!");
 219         exit(EXIT_FAILURE);
 220     }
 221
 222     chksm = zyxel_chksm((const unsigned char *)kernel.data, kernel.size);
 223     size = htonl(kernel.size);
 224
 225     /* 4 bytes:  checksum of the kernel image */
 226     memcpy(kernel_header + ptr, &chksm, 4);
 227     ptr += 4;
 228
 229     /* 4 bytes:  length of the contained kernel image file (big endian) */
 230     memcpy(kernel_header + ptr, &size, 4);
 231
 232     return kernel_header;
 233 }
 234
 235 unsigned int generate_board_header_checksum(char *kernel_hdr, char *rootfs_hdr, char *boardname)
 236 {
 237     char *board_hdr_tmp;
 238     unsigned int sum;
 239     size_t ptr = 0;
 240
 241     /*
 242      * The checksum of the board header is calculated over the first 2048 bytes of
 243      * the header partition with the rootfs checksum used as a placeholder for then
 244      * board checksum we calculate in this step. The checksum gained from this step
 245      * is then used for the final board header partition.
 246      */
 247
 248     board_hdr_tmp = malloc(HEADER_PARTITION_CALC_LENGTH);
 249     if (!board_hdr_tmp) {
 250         ERR("Couldn't allocate memory for temporary board header!");
 251         exit(EXIT_FAILURE);
 252     }
 253     memset(board_hdr_tmp, 0xff, HEADER_PARTITION_CALC_LENGTH);
 254
 255     /* 40 bytes:  RootFS header */
 256     memcpy(board_hdr_tmp, rootfs_hdr, ROOTFS_HEADER_LEN);
 257     ptr += ROOTFS_HEADER_LEN;
 258
 259     /* 4 bytes:  RootFS checksum (BE) as placeholder for board-header checksum */
 260     memcpy(board_hdr_tmp + ptr, rootfs_hdr, 4);
 261     ptr += 4;
 262
 263     /* 32 bytes:  Model (e.g. "NBG6617", NUL termiated, 0xff padded) */
 264     memcpy(board_hdr_tmp + ptr, boardname, strlen(boardname));
 265     ptr += strlen(boardname);
 266     /* Add null-terminator */
 267     board_hdr_tmp[ptr] = 0x0;
 268     ptr = ROOTFS_HEADER_LEN + 4 + BOARD_NAME_LEN;
 269
 270     /* 8 bytes:  Kernel header */
 271     if (kernel_hdr)
 272         memcpy(board_hdr_tmp + ptr, kernel_hdr, 8);
 273
 274     /* Calculate the checksum over the first 2048 bytes */
 275     sum = zyxel_chksm((const unsigned char *)board_hdr_tmp, HEADER_PARTITION_CALC_LENGTH);
 276     free(board_hdr_tmp);
 277     return sum;
 278 }
 279
 280 char *generate_board_header(char *kernel_hdr, char *rootfs_hdr, char *boardname)
 281 {
 282     unsigned int board_checksum;
 283     char *board_hdr;
 284
 285     board_hdr = malloc(BOARD_HEADER_LEN);
 286     if (!board_hdr) {
 287         ERR("Couldn't allocate memory for board header!");
 288         exit(EXIT_FAILURE);
 289     }
 290     memset(board_hdr, 0xff, BOARD_HEADER_LEN);
 291
 292     /* 4 bytes:  checksum over the header partition (big endian) */
 293     board_checksum = generate_board_header_checksum(kernel_hdr, rootfs_hdr, boardname);
 294     memcpy(board_hdr, &board_checksum, 4);
 295
 296     /* 32 bytes:  Model (e.g. "NBG6617", NUL termiated, 0xff padded) */
 297     memcpy(board_hdr + 4, boardname, strlen(boardname));
 298     board_hdr[4 + strlen(boardname)] = 0x0;
 299
 300     return board_hdr;
 301 }
 302
 303 int build_image()
 304 {
 305     char *rootfs_header = NULL;
 306     char *kernel_header = NULL;
 307     char *board_header = NULL;
 308
 309     size_t ptr;
 310
 311     /* Load files */
 312     if (kernel.name)
 313         map_file(&kernel);
 314     map_file(&rootfs);
 315
 316     /* As ZyXEL Web-GUI only accept images with a rootfs equal or larger than the first firmware shipped
 317      * for the device, we need to pad rootfs partition to this size. To perform further calculations, we
 318      * decide the size of this part here. In case the rootfs we want to integrate in our image is larger,
 319      * take it's size, otherwise the supplied size.
 320      *
 321      * Be careful! We rely on assertion of correct size to be performed beforehand. It is unknown if images
 322      * with a to large rootfs are accepted or not.
 323      */
 324     rootfs_out.size = rootfs_size < rootfs.size ? rootfs.size : rootfs_size;
 325
 326     /*
 327      * Allocate memory and copy input rootfs for temporary output rootfs.
 328      * This is important as we have to generate the rootfs checksum over the
 329      * entire rootfs partition. As we might have to pad the partition to allow
 330      * for flashing via ZyXEL's Web-GUI, we prepare the rootfs partition for the
 331      * output image here (and also use it for calculating the rootfs checksum).
 332      *
 333      * The roofs padding has to be done with 0x00.
 334      */
 335     rootfs_out.data = calloc(rootfs_out.size, sizeof(char));
 336     memcpy(rootfs_out.data, rootfs.data, rootfs.size);
 337
 338     /* Prepare headers */
 339     rootfs_header = generate_rootfs_header(rootfs_out, version_name);
 340     if (kernel.name)
 341         kernel_header = generate_kernel_header(kernel);
 342     board_header = generate_board_header(kernel_header, rootfs_header, board_name);
 343
 344     /* Prepare output file */
 345     out.size = header_length + rootfs_out.size;
 346     if (kernel.name)
 347         out.size += kernel.size;
 348     out.data = malloc(out.size);
 349     memset(out.data, 0xFF, out.size);
 350
 351     /* Build output image */
 352     memcpy(out.data, rootfs_header, ROOTFS_HEADER_LEN);
 353     memcpy(out.data + ROOTFS_HEADER_LEN, board_header, BOARD_HEADER_LEN);
 354     if (kernel.name)
 355         memcpy(out.data + ROOTFS_HEADER_LEN + BOARD_HEADER_LEN, kernel_header, KERNEL_HEADER_LEN);
 356     ptr = header_length;
 357     memcpy(out.data + ptr, rootfs_out.data, rootfs_out.size);
 358     ptr += rootfs_out.size;
 359     if (kernel.name)
 360         memcpy(out.data + ptr, kernel.data, kernel.size);
 361
 362     /* Write back output image */
 363     write_file(&out);
 364
 365     /* Free allocated memory */
 366     if (kernel.name)
 367         unmap_file(&kernel);
 368     unmap_file(&rootfs);
 369     free(out.data);
 370     free(rootfs_out.data);
 371
 372     free(rootfs_header);
 373     if (kernel.name)
 374         free(kernel_header);
 375     free(board_header);
 376
 377     return 0;
 378 }
 379
 380 int check_options()
 381 {
 382     if (!rootfs.name) {
 383         ERR("No rootfs filename supplied");
 384         return -2;
 385     }
 386
 387     if (!out.name) {
 388         ERR("No output filename supplied");
 389         return -3;
 390     }
 391
 392     if (!board_name) {
 393         ERR("No board-name supplied");
 394         return -4;
 395     }
 396
 397     if (!version_name) {
 398         ERR("No version supplied");
 399         return -5;
 400     }
 401
 402     if (rootfs_size <= 0) {
 403         ERR("Invalid rootfs size supplied");
 404         return -6;
 405     }
 406
 407     if (strlen(board_name) > 31) {
 408         ERR("Board name is to long");
 409         return -7;
 410     }
 411     return 0;
 412 }
 413
 414 int main(int argc, char *argv[])
 415 {
 416     int ret;
 417     progname = basename(argv[0]);
 418     while (1) {
 419         int c;
 420
 421         c = getopt(argc, argv, "b:k:o:r:s:v:l:h");
 422         if (c == -1)
 423             break;
 424
 425         switch (c) {
 426             case 'b':
 427                 board_name = optarg;
 428                 break;
 429             case 'h':
 430                 usage(EXIT_SUCCESS);
 431                 break;
 432             case 'k':
 433                 kernel.name = optarg;
 434                 break;
 435             case 'o':
 436                 out.name = optarg;
 437                 break;
 438             case 'r':
 439                 rootfs.name = optarg;
 440                 break;
 441             case 's':
 442                 sscanf(optarg, "%u", &rootfs_size);
 443                 break;
 444             case 'v':
 445                 version_name = optarg;
 446                 break;
 447             case 'l':
 448                 sscanf(optarg, "%u", &header_length);
 449                 break;
 450             default:
 451                 usage(EXIT_FAILURE);
 452                 break;
 453         }
 454     }
 455
 456     ret = check_options();
 457     if (ret)
 458         usage(EXIT_FAILURE);
 459
 460     return build_image();
 461 }