/* Copyright 2021 The ChromiumOS Authors * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ #include #include #include #include #include #include #include #include #include "fmap.h" #include "futility.h" #include "gsc_ro.h" #include "host_key21.h" #include "host_keyblock.h" #include "host_misc.h" #include "host_signature.h" /* * for testing purposes let's use * - tests/devkeys/arv_root.vbprivk as the root private key * - tests/devkeys/arv_root.vbpubk as the root public key * used for signing of the platform public key * - tests/devkeys/arv_platform.vbprivk signing platform key * - tests/devkeys/arv_platform.vbpubk - public key used for signature * verification *------------ * Command to create the signed public key block in ~/tmp/packed: * ./build/futility/futility vbutil_keyblock --pack ~/tmp/packed \ --datapubkey tests/devkeys/arv_platform.vbpubk \ --signprivate tests/devkeys/arv_root.vbprivk *------------ * Command to fill RO_GSCVD FMAP area in an AP firmware file. The input AP * firmware file is ~/tmp/image-guybrush.serial.bin, the output signed * AP firmware file is ~/tmp/guybrush-signed: * ./build/futility/futility gscvd --outfile ~/tmp/guybrush-signed \ -R 818100:10000,f00000:100,f80000:2000,f8c000:1000,0x00804000:0x00000800 \ -k ~/tmp/packed -p tests/devkeys/arv_platform.vbprivk -b 5a5a4352 \ -r tests/devkeys/arv_root.vbpubk ~/tmp/image-guybrush.serial.bin *------------ * Command to validate a previously signed AP firmware file. The hash is the * sha256sum of tests/devkeys/kernel_subkey.vbpubk: * build/futility/futility gscvd ~/tmp/guybrush-signed \ 3d74429f35be8d34bcb425d4397e2218e6961afed456a78ce30047f5b54ed158 */ /* Command line options processing support. */ enum no_short_opts { OPT_OUTFILE = 1000, OPT_RO_GSCVD_FILE = 1001, }; static const struct option long_opts[] = { /* name hasarg *flag val */ {"add_gbb", 0, NULL, 'G'}, {"board_id", 1, NULL, 'b'}, {"help", 0, NULL, 'h'}, {"keyblock", 1, NULL, 'k'}, {"outfile", 1, NULL, OPT_OUTFILE}, {"platform_priv", 1, NULL, 'p'}, {"ranges", 1, NULL, 'R'}, {"gscvd_out", 1, NULL, OPT_RO_GSCVD_FILE}, {"root_pub_key", 1, NULL, 'r'}, {} }; static const char *short_opts = "R:Gb:hk:p:r:"; static const char usage[] = "\n" "This utility creates an RO verification space in the Chrome OS AP\n" "firmware image, allows to validate a previously prepared image\n" "containing the RO verification space, and prints out the hash of the\n" "payload of the root public key.\n\n" "Create a new GSCVD from scratch:\n" " "MYNAME" gscvd -R PARAMS \n\n" "Re-sign an existing GSCVD with new keys, preserving ranges:\n" " "MYNAME" gscvd PARAMS \n\n" "Validate an existing GSCVD with given root key hash:\n" " "MYNAME" gscvd []\n\n" "Print the hash of a public root key:\n" " "MYNAME" gscvd -r \n\n" "Required PARAMS:\n" " -b|--board_id The Board ID of the board for\n" " which the image is signed.\n" " Can be passed as a 4-letter\n" " string or a hexadecimal number.\n" " -r|--root_pub_key The main public key, in .vbpubk\n" " format, used to verify platform\n" " key\n" " -k|--keyblock Signed platform public key in\n" " .keyblock format, used for run\n" " time RO verifcation\n" " -p|--platform_priv Private platform key in .vbprivk\n" " format, used for signing RO\n" " verification data\n" "Optional PARAMS:\n" " -G|--add_gbb Add the `GBB` FMAP section to the\n" " ranges covered by the signature.\n" " This option takes special care\n" " to exclude the HWID (and its\n" " digest) from this range.\n" " -R|--ranges STRING Comma separated colon delimited\n" " hex tuples :, the\n" " areas of the RO covered by the\n" " signature, if omitted the\n" " ranges are expected to be\n" " present in the GSCVD section\n" " of the input file\n" " [--outfile] OUTFILE Output firmware image containing\n" " RO verification information\n" " [--gscvd_out] GSCVD_FILE A binary blob containing just the\n" " unpadded RO_GSCVD section\n" " -h|--help Print this message\n\n"; /* Structure helping to keep track of the file mapped into memory. */ struct file_buf { uint32_t len; uint8_t *data; int fd; FmapAreaHeader *ro_gscvd; /* Cached GBB information. */ const FmapAreaHeader *gbb_area; uint32_t gbb_maxlen; }; /* * Max number of RO ranges to cover. 32 is more than enough, this must be kept * in sync with APRO_MAX_NUM_RANGES declaration in * common/ap_ro_integrity_check.c in the Cr50 tree. */ #define MAX_RANGES 32 /* * Container keeping track of the set of ranges to include in hash * calculation. */ struct gscvd_ro_ranges { size_t range_count; struct gscvd_ro_range ranges[MAX_RANGES]; }; /** * Load the AP firmware file into memory. * * Map the requested file into memory, find RO_GSCVD area in the file, and * cache the information in the passed in file_buf structure. * * @param file_name name of the AP firmware file * @param file_buf pointer to the helper structure keeping information about * the file * * @return 0 on success 1 on failure. */ static int load_ap_firmware(const char *file_name, struct file_buf *file, int mode) { memset(file, 0, sizeof(*file)); if (futil_open_and_map_file(file_name, &file->fd, mode, &file->data, &file->len)) return 1; if (!fmap_find_by_name(file->data, file->len, NULL, "RO_GSCVD", &file->ro_gscvd)) { ERROR("Could not find RO_GSCVD in the FMAP\n"); futil_unmap_and_close_file(file->fd, mode, file->data, file->len); file->fd = -1; file->data = NULL; file->len = 0; return 1; } /* * Try finding FMAP gbb area and validating the GBB. It's not a * failure if GBB is not found, it might not be required after all. */ FmapAreaHeader *area; while (fmap_find_by_name(file->data, file->len, NULL, "GBB", &area)) { struct vb2_gbb_header *gbb; uint32_t maxlen; gbb = (void *)(file->data + area->area_offset); if (!futil_valid_gbb_header(gbb, area->area_size, &maxlen)) { ERROR("GBB is invalid.\n"); break; } /* * This implementation relies on the fact that no meaningful * fields come after the `hwid_digest` field in the header. If * we ever make new GBB versions that add more fields, the * code below and in add_gbb() needs to be adapted. Older * versions than 1.2 or GBBs with a bmpblk are not expected * with GSCVD images. */ if (gbb->major_version != 1 || gbb->minor_version != 2 || gbb->bmpfv_size != 0) { ERROR("Unsupported GBB version.\n"); break; } file->gbb_area = area; file->gbb_maxlen = maxlen; break; } return 0; } /** * Check if the passed in offset falls into the passed in FMAP area. */ static bool in_range(uint32_t offset, const FmapAreaHeader *ah) { return (offset >= ah->area_offset) && (offset <= (ah->area_offset + ah->area_size)); } /** * Check if the passed in range fits into the passed in FMAP area. */ static bool range_fits(const struct gscvd_ro_range *range, const FmapAreaHeader *ah) { if (in_range(range->offset, ah) && in_range(range->offset + range->size, ah)) return true; return false; } /** * Check if the passed in range overlaps with the area. * * @param range pointer to the range to check * @param offset offset of the area to check against * @param size size of the area to check against * * @return true if range overlaps with the area, false otherwise. */ static bool range_overlaps(const struct gscvd_ro_range *range, uint32_t offset, size_t size) { if (((range->offset + range->size) <= offset) || (offset + size) <= range->offset) return false; ERROR("Range %x..+%x overlaps with %x..+%zx\n", range->offset, range->size, offset, size); return true; } /* * Check validity of the passed in ranges. * * All ranges must * - fit into the WP_RO FMAP area * - not overlap with the RO_GSCVD FMAP area * - not overlap with each other * * @param ranges - pointer to the container of ranges to check * @param file - pointer to the file layout descriptor * * @return zero on success, -1 on failures */ static int verify_ranges(const struct gscvd_ro_ranges *ranges, const struct file_buf *file) { size_t i; FmapAreaHeader *wp_ro; FmapAreaHeader *si_all; int errorcount; if (!fmap_find_by_name(file->data, file->len, NULL, "WP_RO", &wp_ro)) { ERROR("Could not find WP_RO in the FMAP\n"); return 1; } /* Intel boards can have an SI_ALL region that's not in WP_RO but is protected by platform-specific mechanisms, and may still contain components that we want to protect from physical attack. */ if (!fmap_find_by_name(file->data, file->len, NULL, "SI_ALL", &si_all)) si_all = NULL; errorcount = 0; for (i = 0; i < ranges->range_count; i++) { size_t j; /* Must fit into WP_RO or SI_ALL. */ if (!range_fits(ranges->ranges + i, wp_ro) && (!si_all || !range_fits(ranges->ranges + i, si_all))) { ERROR("Range %#x..+%#x does not fit in WP_RO/SI_ALL\n", ranges->ranges[i].offset, ranges->ranges[i].size); errorcount++; } /* Must not overlap with RO_GSCVD. */ if (range_overlaps(ranges->ranges + i, file->ro_gscvd->area_offset, file->ro_gscvd->area_size)) errorcount++; /* The last range is nothing to compare against. */ if (i == ranges->range_count - 1) break; /* Must not overlap with all following ranges. */ for (j = i + 1; j < ranges->range_count; j++) if (range_overlaps(ranges->ranges + i, ranges->ranges[j].offset, ranges->ranges[j].size)) errorcount++; } return errorcount ? -1 : 0; } /** * Parse range specification supplied by the user. * * The input is a string of the following format: * :[,:[,...]] * * @param input user input, part of the command line * @param output pointer to the ranges container * * @return zero on success, -1 on failure */ static int parse_ranges(const char *input, struct gscvd_ro_ranges *output) { char *cursor; char *delim; char *str = strdup(input); int rv = 0; if (!str) { ERROR("Failed to allocate memory for ranges string copy!\n"); return -1; } cursor = str; do { char *colon; char *e; if (output->range_count >= ARRAY_SIZE(output->ranges)) { ERROR("Too many ranges!\n"); rv = -1; break; } delim = strchr(cursor, ','); if (delim) *delim = '\0'; colon = strchr(cursor, ':'); if (!colon) { rv = -1; break; } *colon = '\0'; errno = 0; output->ranges[output->range_count].offset = strtol(cursor, &e, 16); if (errno || *e) { rv = -1; break; } output->ranges[output->range_count].size = strtol(colon + 1, &e, 16); if (errno || *e) { rv = -1; break; } output->range_count++; cursor = delim + 1; /* Iterate until there is no more commas. */ } while (delim); free(str); if (rv) ERROR("Misformatted ranges string\n"); return rv; } /** * Add GBB to ranges. * * Splits the `GBB` FMAP section into separate ranges to exclude the HWID string * and the `hwid_digest` field in the header. Will also exclude the empty area * behind the end of the actual GBB data. * * @param ranges pointer to the ranges container * @param file pointer to the AP firmware file layout descriptor */ static int add_gbb(struct gscvd_ro_ranges *ranges, const struct file_buf *file) { if (!file->gbb_area) { ERROR("Could not find a GBB area in the FMAP.\n"); return 1; } const struct vb2_gbb_header *gbb = (void *)(file->data + file->gbb_area->area_offset); uint32_t lower_key_offset = VB2_MIN(gbb->rootkey_offset, gbb->recovery_key_offset); if (gbb->hwid_offset > lower_key_offset) { ERROR("Weird GBB layout (HWID should come first)\n"); return 1; } if (ranges->range_count >= ARRAY_SIZE(ranges->ranges) - 2) { ERROR("Too many ranges, can't fit GBB!\n"); return 1; } ranges->ranges[ranges->range_count].offset = file->gbb_area->area_offset; ranges->ranges[ranges->range_count].size = offsetof(struct vb2_gbb_header, hwid_digest); ranges->range_count++; ranges->ranges[ranges->range_count].offset = file->gbb_area->area_offset + lower_key_offset; ranges->ranges[ranges->range_count].size = file->gbb_maxlen - lower_key_offset; ranges->range_count++; return 0; } /** * Extend AP RO hash digest with data from an address range. * * If the flags_offset value is non zero and happens to fall into the passed * in range, do not read values from flash in the flags_offset..+flags_size * range, instead feed zeros to the hashing function. * * NOTE that flags are expected to fully fit into the range, cases of overlap * are not supported. * * @param ap_firmware_file pointer to the AP firmware file layout descriptor * @param dc pointer to the hash calculating context * @param offset offset of the beginning of the range in AP SPI flash * @param size size of the range * @param flags_offset if nonzero - offset of the GBB flags field in * AP SPI flash * * @return VB2_SUCCESS or digest extension error, if any. */ static vb2_error_t extend_digest(const struct file_buf *ap_firmware_file, struct vb2_digest_context *dc, uint32_t offset, uint32_t size, uint32_t flags_offset) { /* Define it as array to simplify calling vb2_digest_extend() below. */ const uint8_t flags[sizeof(vb2_gbb_flags_t)] = {0}; VB2_DEBUG("%s: %#x..+%#x\n", __func__, offset, size); if (flags_offset && (flags_offset >= offset) && (flags_offset < (offset + size))) { uint32_t flags_size; vb2_error_t rv; /* * This range includes GBB flags, which need to be zeroized. * * First get the hash of up to the flags. */ rv = vb2_digest_extend(dc, ap_firmware_file->data + offset, flags_offset - offset); if (rv != VB2_SUCCESS) return rv; size -= flags_offset - offset; offset = flags_offset; /* Now hash the flag space, maybe partially. */ flags_size = VB2_MIN(size, sizeof(flags)); rv = vb2_digest_extend(dc, flags, flags_size); if (rv != VB2_SUCCESS) return rv; /* Update size and offset to cover the rest of the range. */ size -= flags_size; offset += flags_size; } return vb2_digest_extend(dc,ap_firmware_file->data + offset, size); } /** * Calculate hash of the RO ranges. * * @param ap_firmware_file pointer to the AP firmware file layout descriptor * @param ranges pointer to the container of ranges to include in hash * calculation * @param hash_alg algorithm to use for hashing * @param digest memory to copy the calculated hash to * @param digest_ size requested size of the digest, padded with zeros if the * SHA digest size is smaller than digest_size * @param override_gbb_flags if true, replace GBB flags value with zero * * @return zero on success, -1 on failure. */ static int calculate_ranges_digest(const struct file_buf *ap_firmware_file, const struct gscvd_ro_ranges *ranges, enum vb2_hash_algorithm hash_alg, void *digest, size_t digest_size, bool override_gbb_flags) { struct vb2_digest_context dc; size_t i; uint32_t flags_offset = 0; if (override_gbb_flags && ap_firmware_file->gbb_area) flags_offset = offsetof(struct vb2_gbb_header, flags) + ap_firmware_file->gbb_area->area_offset; /* Calculate the ranges digest. */ if (vb2_digest_init(&dc, false, hash_alg, 0) != VB2_SUCCESS) { ERROR("Failed to init digest!\n"); return 1; } for (i = 0; i < ranges->range_count; i++) { if (extend_digest(ap_firmware_file, &dc, ranges->ranges[i].offset, ranges->ranges[i].size, flags_offset) != VB2_SUCCESS) { ERROR("Failed to extend digest!\n"); return -1; } } memset(digest, 0, digest_size); if (vb2_digest_finalize(&dc, digest, digest_size) != VB2_SUCCESS) { ERROR("Failed to finalize digest!\n"); return -1; } return 0; } /** * Build GSC verification data. * * Calculate size of the structure including the signature and the root key, * allocate memory, fill up the structure, calculate AP RO ranges digest and * then the GVD signature. * * @param ap_firmware_file pointer to the AP firmware file layout descriptor * @param ranges pointer to the container of ranges to include in verification * @param root_pubk pointer to the root pubk container * @param privk pointer to the private key to use for signing * @param board_id Board ID value to use. * * @return pointer to the created GVD (to be freed by the caller) on success, * NULL on failure. */ static struct gsc_verification_data *create_gvd(struct file_buf *ap_firmware_file, struct gscvd_ro_ranges *ranges, const struct vb2_packed_key *root_pubk, const struct vb2_private_key *privk, uint32_t board_id) { struct gsc_verification_data *gvd; size_t total_size; size_t sig_size; size_t ranges_size; struct vb2_signature *sig; const FmapHeader *fmh; sig_size = vb2_rsa_sig_size(privk->sig_alg); ranges_size = ranges->range_count * sizeof(struct gscvd_ro_range); total_size = sizeof(struct gsc_verification_data) + root_pubk->key_size + sig_size + ranges_size; gvd = calloc(total_size, 1); if (!gvd) { ERROR("Failed to allocate %zd bytes for gvd\n", total_size); return NULL; } gvd->gv_magic = GSC_VD_MAGIC; gvd->size = total_size; gvd->gsc_board_id = board_id; gvd->rollback_counter = GSC_VD_ROLLBACK_COUNTER; /* Guaranteed to succeed. */ fmh = fmap_find(ap_firmware_file->data, ap_firmware_file->len); gvd->fmap_location = (uintptr_t)fmh - (uintptr_t)ap_firmware_file->data; gvd->hash_alg = VB2_HASH_SHA256; if (calculate_ranges_digest(ap_firmware_file, ranges, gvd->hash_alg, gvd->ranges_digest, sizeof(gvd->ranges_digest), true)) { free(gvd); return NULL; } /* Prepare signature header. */ vb2_init_signature(&gvd->sig_header, (uint8_t *)(gvd + 1) + ranges_size, sig_size, sizeof(struct gsc_verification_data) + ranges_size); /* Copy root key into the structure. */ vb2_init_packed_key(&gvd->root_key_header, (uint8_t *)(gvd + 1) + ranges_size + sig_size, root_pubk->key_size); vb2_copy_packed_key(&gvd->root_key_header, root_pubk); /* Copy ranges into the ranges section. */ gvd->range_count = ranges->range_count; memcpy(gvd->ranges, ranges->ranges, ranges_size); sig = vb2_calculate_signature((uint8_t *)gvd, sizeof(struct gsc_verification_data) + ranges_size, privk); if (!sig) { ERROR("Failed to calculate signature\n"); free(gvd); return NULL; } /* Copy signature body into GVD after some basic checks. */ if ((sig_size == sig->sig_size) && (gvd->sig_header.data_size == sig->data_size)) { vb2_copy_signature(&gvd->sig_header, sig); } else { ERROR("Inconsistent signature headers\n"); free(sig); free(gvd); return NULL; } free(sig); return gvd; } /** * Fill RO_GSCVD FMAP area. * * All trust chain components have been verified, AP RO sections digest * calculated, and GVD signature created; put it all together in the dedicated * FMAP area and save in a binary blob if requested. * * @param ap_firmware_file pointer to the AP firmware file layout descriptor * @param gvd pointer to the GVD header * @param keyblock pointer to the keyblock container * @param gscvd_file_name if not NULL the name of the file to save the * RO_GSCVD section in. * @return zero on success, -1 on failure */ static int fill_gvd_area(struct file_buf *ap_firmware_file, struct gsc_verification_data *gvd, struct vb2_keyblock *keyblock, const char *gscvd_file_name) { size_t total; uint8_t *cursor; /* How much room is needed for the whole thing? */ total = gvd->size + keyblock->keyblock_size; if (total > ap_firmware_file->ro_gscvd->area_size) { ERROR("GVD section does not fit, %zd > %d\n", total, ap_firmware_file->ro_gscvd->area_size); return -1; } cursor = ap_firmware_file->data + ap_firmware_file->ro_gscvd->area_offset; /* Copy GSC verification data */ memcpy(cursor, gvd, gvd->size); cursor += gvd->size; /* Keyblock, size includes everything. */ memcpy(cursor, keyblock, keyblock->keyblock_size); if (gscvd_file_name) { if (vb2_write_file(gscvd_file_name, cursor - gvd->size, total) != VB2_SUCCESS) return -1; } return 0; } /** * Initialize a work buffer structure. * * Embedded vboot reference code does not use malloc/free, it uses the so * called work buffer structure to provide a poor man's memory management * tool. This program uses some of the embedded library functions, let's * implement work buffer support to keep the embedded code happy. * * @param wb pointer to the workubffer structure to initialize * @param size size of the buffer to allocate * * @return pointer to the allocated buffer on success, NULL on failure. */ static void *init_wb(struct vb2_workbuf *wb, size_t size) { void *buf = malloc(size); if (!buf) ERROR("Failed to allocate workblock of %zd\n", size); else vb2_workbuf_init(wb, buf, size); return buf; } /** * Validate that platform key keyblock was signed by the root key. * * This function performs the same step the GSC is supposed to perform: * validate the platform key keyblock signature using the root public key. * * @param root_pubk pointer to the root public key container * @param kblock pointer to the platform public key keyblock * * @return 0 on success, -1 on failure */ static int validate_pubk_signature(const struct vb2_packed_key *root_pubk, struct vb2_keyblock *kblock) { struct vb2_public_key pubk; struct vb2_workbuf wb; uint32_t kbsize; int rv; void *buf; if (vb2_unpack_key(&pubk, root_pubk) != VB2_SUCCESS) { ERROR("Failed to unpack public key\n"); return -1; } /* Let's create an ample sized work buffer. */ buf = init_wb(&wb, 8192); if (!buf) return -1; rv = -1; do { void *work; kbsize = kblock->keyblock_size; work = vb2_workbuf_alloc(&wb, kbsize); if (!work) { ERROR("Failed to allocate workblock space %d\n", kbsize); break; } memcpy(work, kblock, kbsize); if (vb2_verify_keyblock(work, kbsize, &pubk, &wb) != VB2_SUCCESS) { ERROR("Root and keyblock mismatch\n"); break; } rv = 0; } while (false); free(buf); return rv; } /** * Validate that private and public parts of the platform key match. * * This is a fairly routine validation, the N components of the private and * public RSA keys are compared. * * @param keyblock pointer to the keyblock containing the public key * @param plat_privk pointer to the matching private key * * @return 0 on success, nonzero on failure */ static int validate_privk(struct vb2_keyblock *kblock, struct vb2_private_key *plat_privk) { const BIGNUM *privn; BIGNUM *pubn; struct vb2_public_key pubk; int rv; privn = pubn = NULL; RSA_get0_key(plat_privk->rsa_private_key, &privn, NULL, NULL); if (vb2_unpack_key(&pubk, &kblock->data_key) != VB2_SUCCESS) { ERROR("Failed to unpack public key\n"); return -1; } pubn = BN_new(); pubn = BN_lebin2bn((uint8_t *)pubk.n, vb2_rsa_sig_size(pubk.sig_alg), pubn); rv = BN_cmp(pubn, privn); if (rv) ERROR("Public/private key N mismatch!\n"); BN_free(pubn); return rv; } /** * Copy ranges from AP firmware file into gscvd_ro_ranges container * * While copying the ranges verify that they do not overlap. * * @param ap_firmware_file pointer to the AP firmware file layout descriptor * @param gvd pointer to the GVD header followed by the ranges * @param ranges pointer to the ranges container to copy ranges to * * @return 0 on successful copy nonzero on errors. */ static int copy_ranges(const struct file_buf *ap_firmware_file, const struct gsc_verification_data *gvd, struct gscvd_ro_ranges *ranges) { ranges->range_count = gvd->range_count; memcpy(ranges->ranges, gvd->ranges, sizeof(ranges->ranges[0]) * ranges->range_count); return verify_ranges(ranges, ap_firmware_file); } /** * Basic validation of GVD included in a AP firmware file. * * This is not a cryptographic verification, just a check that the structure * makes sense and the expected values are found in certain fields. * * @param gvd pointer to the GVD header followed by the ranges * @param ap_firmware_file pointer to the AP firmware file layout descriptor * * @return zero on success, -1 on failure. */ static int validate_gvd(const struct gsc_verification_data *gvd, const struct file_buf *ap_firmware_file) { const FmapHeader *fmh; if (gvd->gv_magic != GSC_VD_MAGIC) { ERROR("Incorrect gscvd magic %x\n", gvd->gv_magic); return -1; } if (!gvd->range_count || (gvd->range_count > MAX_RANGES)) { ERROR("Incorrect gscvd range count %d\n", gvd->range_count); return -1; } /* Guaranteed to succeed. */ fmh = fmap_find(ap_firmware_file->data, ap_firmware_file->len); if (gvd->fmap_location != ((uintptr_t)fmh - (uintptr_t)ap_firmware_file->data)) { ERROR("Incorrect gscvd fmap offset %x\n", gvd->fmap_location); return -1; } /* Make sure signature and root key fit. */ if (vb2_verify_signature_inside(gvd, gvd->size, &gvd->sig_header) != VB2_SUCCESS) { ERROR("Corrupted signature header in GVD\n"); return -1; } if (vb2_verify_packed_key_inside(gvd, gvd->size, &gvd->root_key_header) != VB2_SUCCESS) { ERROR("Corrupted root key header in GVD\n"); return -1; } return 0; } /** * Validate GVD signature. * * Given the entire GVD space (header plus ranges array), the signature and * the public key, verify that the signature matches. * * @param gvd pointer to gsc_verification_data followed by the ranges array * @param gvd_signature pointer to the vb2 signature container * @param packedk pointer to the keyblock containing the public key * * @return zero on success, non-zero on failure */ static int validate_gvd_signature(struct gsc_verification_data *gvd, const struct vb2_packed_key *packedk) { struct vb2_workbuf wb; void *buf; int rv; struct vb2_public_key pubk; size_t signed_size; /* Extract public key from the public key keyblock. */ if (vb2_unpack_key(&pubk, packedk) != VB2_SUCCESS) { ERROR("Failed to unpack public key\n"); return -1; } /* Let's create an ample sized work buffer. */ buf = init_wb(&wb, 8192); if (!buf) return -1; signed_size = sizeof(struct gsc_verification_data) + gvd->range_count * sizeof(gvd->ranges[0]); rv = vb2_verify_data((const uint8_t *)gvd, signed_size, &gvd->sig_header, &pubk, &wb); free(buf); return rv; } /* * Try retrieving GVD ranges from the passed in AP firmware file. * * The passed in ranges structure is set to the set of ranges retrieved from * the firmware file, if any. */ static void try_retrieving_ranges_from_the_image(const char *file_name, struct gscvd_ro_ranges *ranges, struct file_buf *ap_firmware_file) { struct gsc_verification_data *gvd; size_t i; ranges->range_count = 0; /* Look for ranges in GVD and copy them if found. */ gvd = (struct gsc_verification_data *)(ap_firmware_file->data + ap_firmware_file->ro_gscvd->area_offset); if (validate_gvd(gvd, ap_firmware_file)) return; if (copy_ranges(ap_firmware_file, gvd, ranges)) return; if (!ranges->range_count) { printf("No ranges found in the input file\n"); } else { printf("Will re-sign the following %zd ranges:\n", ranges->range_count); for (i = 0; i < ranges->range_count; i++) { printf("%08x:%08x\n", ranges->ranges[i].offset, ranges->ranges[i].size); } } } /* * Calculate ranges digest and compare it with the value stored in gvd, with * or without ignoring GBB flags, as requested by the caller. * * @return zero on success, nonzero on failure. */ static int validate_digest(struct file_buf *ap_firmware_file, const struct gscvd_ro_ranges *ranges, const struct gsc_verification_data *gvd, bool override_gbb_flags) { uint8_t digest[sizeof(gvd->ranges_digest)]; if (calculate_ranges_digest(ap_firmware_file, ranges, gvd->hash_alg, digest, sizeof(digest), override_gbb_flags)) { return 1; } return memcmp(digest, gvd->ranges_digest, sizeof(digest)); } /* * Validate GVD of the passed in AP firmware file and possibly the root key hash * * The input parameters are the subset of the command line, the first argv * string is the AP firmware file name, the second string, if present, is the * hash of the root public key included in the RO_GSCVD area of the AP * firmware file. * * @return zero on success, nonzero on failure. */ static int validate_gscvd(int argc, char *argv[]) { struct file_buf ap_firmware_file; int rv; struct gscvd_ro_ranges ranges; struct gsc_verification_data *gvd; const char *file_name; struct vb2_hash root_key_digest = { .algo = VB2_HASH_SHA256 }; /* Guaranteed to be available. */ file_name = argv[0]; if (argc > 1) parse_digest_or_die(root_key_digest.sha256, sizeof(root_key_digest.sha256), argv[1]); do { struct vb2_keyblock *kblock; rv = -1; /* Speculative, will be cleared on success. */ if (load_ap_firmware(file_name, &ap_firmware_file, FILE_RO)) break; /* Copy ranges from gscvd to local structure. */ gvd = (struct gsc_verification_data *)(ap_firmware_file.data + ap_firmware_file.ro_gscvd->area_offset); if (validate_gvd(gvd, &ap_firmware_file)) break; if (copy_ranges(&ap_firmware_file, gvd, &ranges)) break; /* First try validating without ignoring GBB flags. */ if (validate_digest(&ap_firmware_file, &ranges, gvd, false)) { /* It failed, maybe GBB flags are not cleared yet. */ if (validate_digest(&ap_firmware_file, &ranges, gvd, true)) { ERROR("Ranges digest mismatch\n"); break; } WARN("Ranges digest matches with zeroed GBB flags\n"); } /* Find the keyblock. */ kblock = (struct vb2_keyblock *)((uintptr_t)gvd + gvd->size); if ((argc > 1) && (vb2_hash_verify(false, vb2_packed_key_data(&gvd->root_key_header), gvd->root_key_header.key_size, &root_key_digest) != VB2_SUCCESS)) { ERROR("Sha256 mismatch\n"); break; } if (validate_pubk_signature(&gvd->root_key_header, kblock)) { ERROR("Keyblock not signed by root key\n"); break; } if (validate_gvd_signature(gvd, &kblock->data_key)) { ERROR("GVD not signed by platform key\n"); break; } rv = 0; } while (false); if (ap_firmware_file.fd != -1) futil_unmap_and_close_file(ap_firmware_file.fd, FILE_RO, ap_firmware_file.data, ap_firmware_file.len); return rv; } /** * Calculate and report sha256 hash of the public key body. * * The hash will be incorporated into GVC firmware to allow it to validate the * root key. * * @param pubk pointer to the public key to process. */ static void dump_pubk_hash(const struct vb2_packed_key *pubk) { struct vb2_hash hash; size_t i; vb2_hash_calculate(false, vb2_packed_key_data(pubk), pubk->key_size, VB2_HASH_SHA256, &hash); printf("Root key body sha256 hash:\n"); for (i = 0; i < sizeof(hash.sha256); i++) printf("%02x", hash.sha256[i]); printf("\n"); } /** * The main function of this futilty option. * * See the usage string for input details. * * @return zero on success, nonzero on failure. */ static int do_gscvd(int argc, char *argv[]) { int i; int longindex; bool do_gbb = false; char *infile = NULL; char *outfile = NULL; char *work_file = NULL; struct gscvd_ro_ranges ranges; int errorcount = 0; struct vb2_packed_key *root_pubk = NULL; struct vb2_keyblock *kblock = NULL; struct vb2_private_key *plat_privk = NULL; struct gsc_verification_data *gvd = NULL; struct file_buf ap_firmware_file = { .fd = -1 }; uint32_t board_id = UINT32_MAX; char *ro_gscvd_file = NULL; int rv = 0; ranges.range_count = 0; while ((i = getopt_long(argc, argv, short_opts, long_opts, &longindex)) != -1) { switch (i) { case OPT_OUTFILE: outfile = optarg; break; case OPT_RO_GSCVD_FILE: ro_gscvd_file = optarg; break; case 'R': if (parse_ranges(optarg, &ranges)) { ERROR("Could not parse ranges\n"); /* Error message has been already printed. */ errorcount++; } break; case 'G': do_gbb = true; break; case 'b': { char *e; long long bid; if (strlen(optarg) == 4) { board_id = optarg[0] << 24 | optarg[1] << 16 | optarg[2] << 8 | optarg[3]; break; } bid = strtoull(optarg, &e, 16); if (*e || (bid >= UINT32_MAX)) { ERROR("Cannot parse Board ID '%s'\n", optarg); errorcount++; } else { board_id = (uint32_t)bid; } break; } case 'r': root_pubk = vb2_read_packed_key(optarg); if (!root_pubk) { ERROR("Could not read %s\n", optarg); errorcount++; } break; case 'k': kblock = vb2_read_keyblock(optarg); if (!kblock) { ERROR("Could not read %s\n", optarg); errorcount++; } break; case 'p': plat_privk = vb2_read_private_key(optarg); if (!plat_privk) { ERROR("Could not read %s\n", optarg); errorcount++; } break; case 'h': printf("%s", usage); return 0; case '?': if (optopt) ERROR("Unrecognized option: -%c\n", optopt); else ERROR("Unrecognized option: %s\n", argv[optind - 1]); errorcount++; break; case ':': ERROR("Missing argument to -%c\n", optopt); errorcount++; break; case 0: /* handled option */ break; default: FATAL("Unrecognized getopt output: %d\n", i); } } if ((optind == 1) && (argc > 1)) { if (ro_gscvd_file) { ERROR("Unexpected --gscvd_out in command line\n"); goto usage_out; } /* This must be a validation request. */ return validate_gscvd(argc - 1, argv + 1); } if (errorcount) /* Error message(s) should have been printed by now. */ goto usage_out; if (!root_pubk) { ERROR("Missing --root_pub_key argument\n"); goto usage_out; } else if (argc == 3) { if (ro_gscvd_file) { ERROR("Unexpected --gscvd_out in command line\n"); goto usage_out; } /* * This is a request to print out the hash of the root pub key * payload. */ dump_pubk_hash(root_pubk); return 0; } if (optind != (argc - 1)) { ERROR("Misformatted command line\n"); goto usage_out; } infile = argv[optind]; if (!kblock) { ERROR("Missing --keyblock argument\n"); goto usage_out; } if (!plat_privk) { ERROR("Missing --platform_priv argument\n"); goto usage_out; } if (board_id == UINT32_MAX) { ERROR("Missing --board_id argument\n"); goto usage_out; } if (outfile) { if (futil_copy_file(infile, outfile) < 0) exit(1); work_file = outfile; } else { work_file = infile; } do { rv = 1; /* Speculative, will be cleared on success. */ if (validate_pubk_signature(root_pubk, kblock)) break; if (validate_privk(kblock, plat_privk)) break; if (load_ap_firmware(work_file, &ap_firmware_file, FILE_RW)) break; if (!ranges.range_count) try_retrieving_ranges_from_the_image(infile, &ranges, &ap_firmware_file); if (!ranges.range_count && !do_gbb) { ERROR("Missing --ranges argument and no ranges in the input file\n"); break; } if (do_gbb && add_gbb(&ranges, &ap_firmware_file)) break; if (verify_ranges(&ranges, &ap_firmware_file)) break; gvd = create_gvd(&ap_firmware_file, &ranges, root_pubk, plat_privk, board_id); if (!gvd) break; if (fill_gvd_area(&ap_firmware_file, gvd, kblock, ro_gscvd_file)) break; rv = 0; } while (false); free(gvd); free(root_pubk); free(kblock); vb2_private_key_free(plat_privk); if (ap_firmware_file.fd != -1) futil_unmap_and_close_file(ap_firmware_file.fd, FILE_RW, ap_firmware_file.data, ap_firmware_file.len); return rv; usage_out: fputs(usage, stderr); return 1; } DECLARE_FUTIL_COMMAND(gscvd, do_gscvd, VBOOT_VERSION_2_1, "Create RO verification structure");