#include #include #include #include #include #include struct gpt_table_header { // the head char signature[8]; uint32_t revision; uint32_t header_size; uint32_t crc32; uint32_t _reserved0; // the partitioning info uint64_t my_lba; uint64_t alternate_lba; uint64_t first_usable_lba; uint64_t last_usable_lba; // the guid uint64_t disk_guid[2]; // entries related uint64_t partition_entry_lba; uint32_t number_of_partition_entries; uint32_t size_of_partition_entry; uint32_t partition_entry_array_crc32; } __attribute__((packed)); struct gpt_entry { uint64_t partition_type_guid[2]; uint64_t unique_partition_guid[2]; uint64_t starting_lba; uint64_t ending_lba; uint64_t attributes; uint16_t partition_name[36]; } __attribute__((packed)); // This table from https://web.mit.edu/freebsd/head/sys/libkern/crc32.c const uint32_t crc32_table[] = { 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d }; static uint32_t crc32(void *_stream, size_t len) { uint8_t *stream = _stream; uint32_t ret = 0xffffffff; for (size_t i = 0; i < len; i++) { ret = (ret >> 8) ^ crc32_table[(ret ^ stream[i]) & 0xff]; } ret ^= 0xffffffff; return ret; } int main(int argc, char *argv[]) { int ok = 1; FILE *bootloader_file = NULL, *device = NULL; uint8_t *bootloader_img = NULL; uint8_t orig_mbr[70], timestamp[6]; if (argc < 3) { printf("Usage: %s [GPT partition index]\n", argv[0]); return 1; } bootloader_file = fopen(argv[1], "rb"); if (bootloader_file == NULL) { perror("Error: "); return 1; } fseek(bootloader_file, 0, SEEK_END); size_t bootloader_file_size = ftell(bootloader_file); bootloader_img = malloc(bootloader_file_size); if (bootloader_img == NULL) { perror("Error: "); goto cleanup; } // Load in bootloader image fseek(bootloader_file, 0, SEEK_SET); fread(bootloader_img, 1, bootloader_file_size, bootloader_file); device = fopen(argv[2], "r+b"); if (device == NULL) { perror("Error: "); goto cleanup; } // Probe for GPT and logical block size int gpt = 0; struct gpt_table_header gpt_header; uint64_t lb_guesses[] = { 512, 4096 }; uint64_t lb_size; for (size_t i = 0; i < sizeof(lb_guesses) / sizeof(uint64_t); i++) { fseek(device, lb_guesses[i], SEEK_SET); fread(&gpt_header, sizeof(struct gpt_table_header), 1, device); if (!strncmp(gpt_header.signature, "EFI PART", 8)) { gpt = 1; lb_size = lb_guesses[i]; fprintf(stderr, "Installing to GPT. Logical block size of %" PRIu64 " bytes.\n", lb_guesses[i]); break; } } struct gpt_table_header secondary_gpt_header; if (gpt) { fprintf(stderr, "Secondary header at LBA 0x%" PRIx64 ".\n", gpt_header.alternate_lba); fseek(device, lb_size * gpt_header.alternate_lba, SEEK_SET); fread(&secondary_gpt_header, sizeof(struct gpt_table_header), 1, device); if (!strncmp(secondary_gpt_header.signature, "EFI PART", 8)) { fprintf(stderr, "Secondary header valid.\n"); } else { fprintf(stderr, "Secondary header not valid, aborting.\n"); goto cleanup; } } size_t stage2_size = bootloader_file_size - 512; uint16_t stage2_size_a = stage2_size / 2 + stage2_size % 2; uint16_t stage2_size_b = stage2_size / 2; // Default split of stage2 for MBR (consecutive in post MBR gap) uint64_t stage2_loc_a = 512; uint64_t stage2_loc_b = stage2_loc_a + stage2_size_a; if (stage2_loc_b & (512 - 1)) stage2_loc_b = (stage2_loc_b + 512) & ~(512 - 1); if (gpt) { if (argc > 3) { uint32_t partition_num; sscanf(argv[3], "%" SCNu32, &partition_num); partition_num--; if (partition_num > gpt_header.number_of_partition_entries) { fprintf(stderr, "error: Partition number is too large.\n"); goto cleanup; } struct gpt_entry gpt_entry; fseek(device, (gpt_header.partition_entry_lba * lb_size) + (partition_num * sizeof(struct gpt_entry)), SEEK_SET); fread(&gpt_entry, sizeof(struct gpt_entry), 1, device); if (gpt_entry.unique_partition_guid[0] == 0 && gpt_entry.unique_partition_guid[1] == 0) { fprintf(stderr, "error: No such partition.\n"); goto cleanup; } fprintf(stderr, "GPT partition specified. Installing there instead of embedding.\n"); stage2_loc_a = gpt_entry.starting_lba * lb_size; stage2_loc_b = stage2_loc_a + stage2_size_a; if (stage2_loc_b & (lb_size - 1)) stage2_loc_b = (stage2_loc_b + lb_size) & ~(lb_size - 1); } else { fprintf(stderr, "GPT partition NOT specified. Attempting GPT embedding.\n"); ssize_t max_partition_entry_used = -1; for (ssize_t i = 0; i < gpt_header.number_of_partition_entries; i++) { struct gpt_entry gpt_entry; fseek(device, (gpt_header.partition_entry_lba * lb_size) + (i * sizeof(struct gpt_entry)), SEEK_SET); fread(&gpt_entry, sizeof(struct gpt_entry), 1, device); if (gpt_entry.unique_partition_guid[0] != 0 || gpt_entry.unique_partition_guid[1] != 0) { if (i > max_partition_entry_used) max_partition_entry_used = i; } } stage2_loc_a = (gpt_header.partition_entry_lba + 32) * lb_size; stage2_loc_a -= stage2_size_a; stage2_loc_a &= ~(lb_size - 1); stage2_loc_b = (secondary_gpt_header.partition_entry_lba + 32) * lb_size; stage2_loc_b -= stage2_size_b; stage2_loc_b &= ~(lb_size - 1); size_t partition_entries_per_lb = lb_size / gpt_header.size_of_partition_entry; size_t new_partition_array_lba_size = stage2_loc_a / lb_size - gpt_header.partition_entry_lba; size_t new_partition_entry_count = new_partition_array_lba_size * partition_entries_per_lb; if ((ssize_t)new_partition_array_lba_size <= max_partition_entry_used) { fprintf(stderr, "error: Cannot embed because there are too many used partition entries.\n"); goto cleanup; } uint8_t *partition_array = malloc(new_partition_entry_count * gpt_header.size_of_partition_entry); if (partition_array == NULL) { perror("Error: "); goto cleanup; } fseek(device, gpt_header.partition_entry_lba * lb_size, SEEK_SET); fread(partition_array, new_partition_entry_count * gpt_header.size_of_partition_entry, 1, device); uint32_t crc32_partition_array = crc32(partition_array, new_partition_entry_count * gpt_header.size_of_partition_entry); free(partition_array); gpt_header.partition_entry_array_crc32 = crc32_partition_array; gpt_header.number_of_partition_entries = new_partition_entry_count; gpt_header.crc32 = 0; gpt_header.crc32 = crc32(&gpt_header, sizeof(struct gpt_table_header)); fseek(device, lb_size, SEEK_SET); fwrite(&gpt_header, sizeof(struct gpt_table_header), 1, device); secondary_gpt_header.partition_entry_array_crc32 = crc32_partition_array; secondary_gpt_header.number_of_partition_entries = new_partition_entry_count; secondary_gpt_header.crc32 = 0; secondary_gpt_header.crc32 = crc32(&secondary_gpt_header, sizeof(struct gpt_table_header)); fseek(device, lb_size * gpt_header.alternate_lba, SEEK_SET); fwrite(&secondary_gpt_header, sizeof(struct gpt_table_header), 1, device); } } else { fprintf(stderr, "Installing to MBR.\n"); } fprintf(stderr, "Stage 2 to be located at 0x%" PRIx64 " and 0x%" PRIx64 ".\n", stage2_loc_a, stage2_loc_b); // Save original timestamp fseek(device, 218, SEEK_SET); fread(timestamp, 1, 6, device); // Save the original partition table of the device fseek(device, 440, SEEK_SET); fread(orig_mbr, 1, 70, device); // Write the bootsector from the bootloader to the device fseek(device, 0, SEEK_SET); fwrite(&bootloader_img[0], 1, 512, device); // Write the rest of stage 2 to the device fseek(device, stage2_loc_a, SEEK_SET); fwrite(&bootloader_img[512], 1, stage2_size_a, device); fseek(device, stage2_loc_b, SEEK_SET); fwrite(&bootloader_img[512 + stage2_size_a], 1, stage2_size_b, device); // Hardcode in the bootsector the location of stage 2 halves fseek(device, 0x1a4, SEEK_SET); fwrite(&stage2_size_a, 1, sizeof(uint16_t), device); fwrite(&stage2_size_b, 1, sizeof(uint16_t), device); fwrite(&stage2_loc_a, 1, sizeof(uint64_t), device); fwrite(&stage2_loc_b, 1, sizeof(uint64_t), device); // Write back timestamp fseek(device, 218, SEEK_SET); fwrite(timestamp, 1, 6, device); // Write back the saved partition table to the device fseek(device, 440, SEEK_SET); fwrite(orig_mbr, 1, 70, device); ok = 0; cleanup: if (device) fclose(device); if (bootloader_file) fclose(bootloader_file); if (bootloader_img) free(bootloader_img); return ok; }