| /* |
| * Copyright (c) 2014 Travis Geiselbrecht |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining |
| * a copy of this software and associated documentation files |
| * (the "Software"), to deal in the Software without restriction, |
| * including without limitation the rights to use, copy, modify, merge, |
| * publish, distribute, sublicense, and/or sell copies of the Software, |
| * and to permit persons to whom the Software is furnished to do so, |
| * subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be |
| * included in all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| */ |
| |
| #include <lib/bootimage.h> |
| #include <trace.h> |
| #include <err.h> |
| #include <debug.h> |
| #include <stdlib.h> |
| #include <string.h> |
| |
| #include <lib/bootimage_struct.h> |
| #include <lib/mincrypt/sha256.h> |
| |
| #define LOCAL_TRACE 1 |
| |
| struct bootimage { |
| const uint8_t *ptr; |
| size_t len; |
| }; |
| |
| static status_t validate_bootimage(bootimage_t *bi) |
| { |
| if (!bi) |
| return ERR_INVALID_ARGS; |
| |
| /* is it large enough to hold the first entry */ |
| if (bi->len < 4096) { |
| LTRACEF("bootentry too short\n"); |
| return ERR_BAD_LEN; |
| } |
| |
| bootentry *be = (bootentry *)bi->ptr; |
| |
| /* check that the first entry is a file, type boot info, and is 4096 bytes at offset 0 */ |
| if (be->kind != KIND_FILE || |
| be->file.type != TYPE_BOOT_IMAGE || |
| be->file.offset != 0 || |
| be->file.length != 4096 || |
| memcmp(be->file.name, BOOT_MAGIC, sizeof(be->file.name))) { |
| LTRACEF("invalid first entry\n"); |
| return ERR_INVALID_ARGS; |
| } |
| |
| /* check the sha256 of the rest of the first page */ |
| SHA256_CTX ctx; |
| SHA256_init(&ctx); |
| |
| SHA256_update(&ctx, be + 1, 4096 - sizeof(bootentry)); |
| const uint8_t *hash = SHA256_final(&ctx); |
| |
| if (memcmp(hash, be->file.sha256, sizeof(be->file.sha256)) != 0) { |
| LTRACEF("bad hash of first section\n"); |
| |
| return ERR_CHECKSUM_FAIL; |
| } |
| |
| /* look at the second entry, which should be a boot info structure */ |
| if (be[1].kind != KIND_BOOT_INFO) { |
| LTRACEF("second entry not boot info\n"); |
| return ERR_INVALID_ARGS; |
| } |
| |
| bootentry_info *info = &be[1].info; |
| |
| /* is the image a handled version */ |
| if (info->version > BOOT_VERSION) { |
| LTRACEF("unhandled version 0x%x\n", info->version); |
| return ERR_INVALID_ARGS; |
| } |
| |
| /* is the image the right size? */ |
| if (info->image_size > bi->len) { |
| LTRACEF("boot image block says image is too big (0x%x bytes)\n", info->image_size); |
| return ERR_INVALID_ARGS; |
| } |
| |
| /* trim the len to what the info block says */ |
| bi->len = info->image_size; |
| |
| /* iterate over the remaining entries in the list */ |
| for (size_t i = 2; i < info->entry_count; i++) { |
| if (be[i].kind == 0) |
| break; |
| |
| LTRACEF("%u: kind 0x%x\n", i, be[i].kind); |
| |
| switch (be[i].kind) { |
| case KIND_BOOT_INFO: |
| break; |
| case KIND_BOARD: |
| break; |
| case KIND_BUILD: |
| break; |
| case KIND_FILE: { |
| LTRACEF("\ttype %c%c%c%c offset 0x%x, length 0x%x\n", |
| (be[i].file.type >> 0) & 0xff, (be[i].file.type >> 8) & 0xff, |
| (be[i].file.type >> 16) & 0xff, (be[i].file.type >> 24) & 0xff, |
| be[i].file.offset, be[i].file.length); |
| |
| /* check that the file section is inside the overall image */ |
| uint32_t end = be[i].file.offset + be[i].file.length; |
| if (end < be[i].file.offset || end > info->image_size) { |
| LTRACEF("bad file section, size too large\n"); |
| return ERR_INVALID_ARGS; |
| } |
| |
| /* check the sha256 hash */ |
| SHA256_init(&ctx); |
| |
| LTRACEF("\tvalidating SHA256 hash\n"); |
| SHA256_update(&ctx, (const uint8_t *)bi->ptr + be[i].file.offset, be[i].file.length); |
| const uint8_t *hash = SHA256_final(&ctx); |
| |
| if (memcmp(hash, be[i].file.sha256, sizeof(be[i].file.sha256)) != 0) { |
| LTRACEF("bad hash of file section\n"); |
| |
| return ERR_CHECKSUM_FAIL; |
| } |
| |
| break; |
| } |
| default: |
| LTRACEF("unknown kind 0x%x\n", be[i].kind); |
| return ERR_INVALID_ARGS; |
| } |
| } |
| |
| LTRACEF("image good\n"); |
| return NO_ERROR; |
| } |
| |
| status_t bootimage_open(const void *ptr, size_t len, bootimage_t **bi) |
| { |
| LTRACEF("ptr %p, len %zu\n", ptr, len); |
| |
| if (!bi) |
| return ERR_INVALID_ARGS; |
| |
| *bi = calloc(1, sizeof(bootimage_t)); |
| if (!*bi) |
| return ERR_NO_MEMORY; |
| |
| (*bi)->ptr = ptr; |
| (*bi)->len = len; |
| |
| /* try to validate it */ |
| status_t err = validate_bootimage(*bi); |
| if (err < 0) { |
| bootimage_close(*bi); |
| return err; |
| } |
| |
| return NO_ERROR; |
| } |
| |
| status_t bootimage_close(bootimage_t *bi) |
| { |
| if (bi) |
| free(bi); |
| |
| return NO_ERROR; |
| } |
| |
| status_t bootimage_get_range(bootimage_t *bi, const void **ptr, size_t *len) |
| { |
| if (!bi) |
| return ERR_INVALID_ARGS; |
| |
| if (ptr) |
| *ptr = bi->ptr; |
| if (len) |
| *len = bi->len; |
| |
| return NO_ERROR; |
| } |
| |
| status_t bootimage_get_file_section(bootimage_t *bi, uint32_t type, const void **ptr, size_t *len) |
| { |
| if (!bi) |
| return ERR_INVALID_ARGS; |
| |
| bootentry *be = (bootentry *)bi->ptr; |
| bootentry_info *info = &be[1].info; |
| |
| for (size_t i = 2; i < info->entry_count; i++) { |
| if (be[i].kind == 0) |
| break; |
| |
| if (be[i].kind != KIND_FILE) |
| continue; |
| |
| if (type == be[i].file.type) { |
| if (ptr) |
| *ptr = bi->ptr + be[i].file.offset; |
| if (len) |
| *len = be[i].file.length; |
| return NO_ERROR; |
| } |
| } |
| |
| return ERR_NOT_FOUND; |
| } |
| |