// SPDX-License-Identifier: MIT /* * Copyright (C) 2016 The Android Open Source Project */ #include "avb_slot_verify.h" #include "avb_chain_partition_descriptor.h" #include "avb_cmdline.h" #include "avb_footer.h" #include "avb_hash_descriptor.h" #include "avb_hashtree_descriptor.h" #include "avb_kernel_cmdline_descriptor.h" #include "avb_sha.h" #include "avb_util.h" #include "avb_vbmeta_image.h" #include "avb_version.h" /* Maximum number of partitions that can be loaded with avb_slot_verify(). */ #define MAX_NUMBER_OF_LOADED_PARTITIONS 32 /* Maximum number of vbmeta images that can be loaded with avb_slot_verify(). */ #define MAX_NUMBER_OF_VBMETA_IMAGES 32 /* Maximum size of a vbmeta image - 64 KiB. */ #define VBMETA_MAX_SIZE (64 * 1024) /* Helper function to see if we should continue with verification in * allow_verification_error=true mode if something goes wrong. See the * comments for the avb_slot_verify() function for more information. */ static inline bool result_should_continue(AvbSlotVerifyResult result) { switch (result) { case AVB_SLOT_VERIFY_RESULT_ERROR_OOM: case AVB_SLOT_VERIFY_RESULT_ERROR_IO: case AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA: case AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION: case AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT: return false; case AVB_SLOT_VERIFY_RESULT_OK: case AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION: case AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX: case AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED: return true; } return false; } static AvbSlotVerifyResult load_full_partition(AvbOps* ops, const char* part_name, uint64_t image_size, uint8_t** out_image_buf, bool* out_image_preloaded) { size_t part_num_read; AvbIOResult io_ret; /* Make sure that we do not overwrite existing data. */ avb_assert(*out_image_buf == NULL); avb_assert(!*out_image_preloaded); /* We are going to implicitly cast image_size from uint64_t to size_t in the * following code, so we need to make sure that the cast is safe. */ if (image_size != (size_t)(image_size)) { avb_errorv(part_name, ": Partition size too large to load.\n", NULL); return AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; } /* Try use a preloaded one. */ if (ops->get_preloaded_partition != NULL) { io_ret = ops->get_preloaded_partition( ops, part_name, image_size, out_image_buf, &part_num_read); if (io_ret == AVB_IO_RESULT_ERROR_OOM) { return AVB_SLOT_VERIFY_RESULT_ERROR_OOM; } else if (io_ret != AVB_IO_RESULT_OK) { avb_errorv(part_name, ": Error loading data from partition.\n", NULL); return AVB_SLOT_VERIFY_RESULT_ERROR_IO; } if (*out_image_buf != NULL) { if (part_num_read != image_size) { avb_errorv(part_name, ": Read incorrect number of bytes.\n", NULL); return AVB_SLOT_VERIFY_RESULT_ERROR_IO; } *out_image_preloaded = true; } } /* Allocate and copy the partition. */ if (!*out_image_preloaded) { *out_image_buf = avb_malloc(image_size); if (*out_image_buf == NULL) { return AVB_SLOT_VERIFY_RESULT_ERROR_OOM; } io_ret = ops->read_from_partition(ops, part_name, 0 /* offset */, image_size, *out_image_buf, &part_num_read); if (io_ret == AVB_IO_RESULT_ERROR_OOM) { return AVB_SLOT_VERIFY_RESULT_ERROR_OOM; } else if (io_ret != AVB_IO_RESULT_OK) { avb_errorv(part_name, ": Error loading data from partition.\n", NULL); return AVB_SLOT_VERIFY_RESULT_ERROR_IO; } if (part_num_read != image_size) { avb_errorv(part_name, ": Read incorrect number of bytes.\n", NULL); return AVB_SLOT_VERIFY_RESULT_ERROR_IO; } } return AVB_SLOT_VERIFY_RESULT_OK; } static AvbSlotVerifyResult read_persistent_digest(AvbOps* ops, const char* part_name, size_t expected_digest_size, uint8_t* out_digest) { char* persistent_value_name = NULL; AvbIOResult io_ret = AVB_IO_RESULT_OK; size_t stored_digest_size = 0; if (ops->read_persistent_value == NULL) { avb_errorv(part_name, ": Persistent values are not implemented.\n", NULL); return AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; } persistent_value_name = avb_strdupv(AVB_NPV_PERSISTENT_DIGEST_PREFIX, part_name, NULL); if (persistent_value_name == NULL) { return AVB_SLOT_VERIFY_RESULT_ERROR_OOM; } io_ret = ops->read_persistent_value(ops, persistent_value_name, expected_digest_size, out_digest, &stored_digest_size); avb_free(persistent_value_name); if (io_ret == AVB_IO_RESULT_ERROR_OOM) { return AVB_SLOT_VERIFY_RESULT_ERROR_OOM; } else if (io_ret == AVB_IO_RESULT_ERROR_NO_SUCH_VALUE) { avb_errorv(part_name, ": Persistent digest does not exist.\n", NULL); return AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; } else if (io_ret == AVB_IO_RESULT_ERROR_INVALID_VALUE_SIZE || io_ret == AVB_IO_RESULT_ERROR_INSUFFICIENT_SPACE || expected_digest_size != stored_digest_size) { avb_errorv( part_name, ": Persistent digest is not of expected size.\n", NULL); return AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; } else if (io_ret != AVB_IO_RESULT_OK) { avb_errorv(part_name, ": Error reading persistent digest.\n", NULL); return AVB_SLOT_VERIFY_RESULT_ERROR_IO; } return AVB_SLOT_VERIFY_RESULT_OK; } static AvbSlotVerifyResult load_and_verify_hash_partition( AvbOps* ops, const char* const* requested_partitions, const char* ab_suffix, bool allow_verification_error, const AvbDescriptor* descriptor, AvbSlotVerifyData* slot_data) { AvbHashDescriptor hash_desc; const uint8_t* desc_partition_name = NULL; const uint8_t* desc_salt; const uint8_t* desc_digest; char part_name[AVB_PART_NAME_MAX_SIZE]; AvbSlotVerifyResult ret; AvbIOResult io_ret; uint8_t* image_buf = NULL; bool image_preloaded = false; uint8_t* digest; size_t digest_len; const char* found; uint64_t image_size; size_t expected_digest_len = 0; uint8_t expected_digest_buf[AVB_SHA512_DIGEST_SIZE]; const uint8_t* expected_digest = NULL; if (!avb_hash_descriptor_validate_and_byteswap( (const AvbHashDescriptor*)descriptor, &hash_desc)) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } desc_partition_name = ((const uint8_t*)descriptor) + sizeof(AvbHashDescriptor); desc_salt = desc_partition_name + hash_desc.partition_name_len; desc_digest = desc_salt + hash_desc.salt_len; if (!avb_validate_utf8(desc_partition_name, hash_desc.partition_name_len)) { avb_error("Partition name is not valid UTF-8.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } /* Don't bother loading or validating unless the partition was * requested in the first place. */ found = avb_strv_find_str(requested_partitions, (const char*)desc_partition_name, hash_desc.partition_name_len); if (found == NULL) { ret = AVB_SLOT_VERIFY_RESULT_OK; goto out; } if ((hash_desc.flags & AVB_HASH_DESCRIPTOR_FLAGS_DO_NOT_USE_AB) != 0) { /* No ab_suffix, just copy the partition name as is. */ if (hash_desc.partition_name_len >= AVB_PART_NAME_MAX_SIZE) { avb_error("Partition name does not fit.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } avb_memcpy(part_name, desc_partition_name, hash_desc.partition_name_len); part_name[hash_desc.partition_name_len] = '\0'; } else if (hash_desc.digest_len == 0 && avb_strlen(ab_suffix) != 0) { /* No ab_suffix allowed for partitions without a digest in the descriptor * because these partitions hold data unique to this device and are not * updated using an A/B scheme. */ avb_error("Cannot use A/B with a persistent digest.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } else { /* Add ab_suffix to the partition name. */ if (!avb_str_concat(part_name, sizeof part_name, (const char*)desc_partition_name, hash_desc.partition_name_len, ab_suffix, avb_strlen(ab_suffix))) { avb_error("Partition name and suffix does not fit.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } } /* If we're allowing verification errors then hash_desc.image_size * may no longer match what's in the partition... so in this case * just load the entire partition. * * For example, this can happen if a developer does 'fastboot flash * boot /path/to/new/and/bigger/boot.img'. We want this to work * since it's such a common workflow. */ image_size = hash_desc.image_size; if (allow_verification_error) { if (ops->get_size_of_partition == NULL) { avb_errorv(part_name, ": The get_size_of_partition() operation is " "not implemented so we may not load the entire partition. " "Please implement.", NULL); } else { io_ret = ops->get_size_of_partition(ops, part_name, &image_size); if (io_ret == AVB_IO_RESULT_ERROR_OOM) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } else if (io_ret != AVB_IO_RESULT_OK) { avb_errorv(part_name, ": Error determining partition size.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; goto out; } avb_debugv(part_name, ": Loading entire partition.\n", NULL); } } ret = load_full_partition( ops, part_name, image_size, &image_buf, &image_preloaded); if (ret != AVB_SLOT_VERIFY_RESULT_OK) { goto out; } if (avb_strcmp((const char*)hash_desc.hash_algorithm, "sha256") == 0) { AvbSHA256Ctx sha256_ctx; avb_sha256_init(&sha256_ctx); avb_sha256_update(&sha256_ctx, desc_salt, hash_desc.salt_len); avb_sha256_update(&sha256_ctx, image_buf, hash_desc.image_size); digest = avb_sha256_final(&sha256_ctx); digest_len = AVB_SHA256_DIGEST_SIZE; } else if (avb_strcmp((const char*)hash_desc.hash_algorithm, "sha512") == 0) { AvbSHA512Ctx sha512_ctx; avb_sha512_init(&sha512_ctx); avb_sha512_update(&sha512_ctx, desc_salt, hash_desc.salt_len); avb_sha512_update(&sha512_ctx, image_buf, hash_desc.image_size); digest = avb_sha512_final(&sha512_ctx); digest_len = AVB_SHA512_DIGEST_SIZE; } else { avb_errorv(part_name, ": Unsupported hash algorithm.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } if (hash_desc.digest_len == 0) { // Expect a match to a persistent digest. avb_debugv(part_name, ": No digest, using persistent digest.\n", NULL); expected_digest_len = digest_len; expected_digest = expected_digest_buf; avb_assert(expected_digest_len <= sizeof(expected_digest_buf)); ret = read_persistent_digest(ops, part_name, digest_len, expected_digest_buf); if (ret != AVB_SLOT_VERIFY_RESULT_OK) { goto out; } } else { // Expect a match to the digest in the descriptor. expected_digest_len = hash_desc.digest_len; expected_digest = desc_digest; } if (digest_len != expected_digest_len) { avb_errorv( part_name, ": Digest in descriptor not of expected size.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } if (avb_safe_memcmp(digest, expected_digest, digest_len) != 0) { avb_errorv(part_name, ": Hash of data does not match digest in descriptor.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION; goto out; } ret = AVB_SLOT_VERIFY_RESULT_OK; out: /* If it worked and something was loaded, copy to slot_data. */ if ((ret == AVB_SLOT_VERIFY_RESULT_OK || result_should_continue(ret)) && image_buf != NULL) { AvbPartitionData* loaded_partition; if (slot_data->num_loaded_partitions == MAX_NUMBER_OF_LOADED_PARTITIONS) { avb_errorv(part_name, ": Too many loaded partitions.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto fail; } loaded_partition = &slot_data->loaded_partitions[slot_data->num_loaded_partitions++]; loaded_partition->partition_name = avb_strdup(found); loaded_partition->data_size = image_size; loaded_partition->data = image_buf; loaded_partition->preloaded = image_preloaded; image_buf = NULL; } fail: if (image_buf != NULL && !image_preloaded) { avb_free(image_buf); } return ret; } static AvbSlotVerifyResult load_requested_partitions( AvbOps* ops, const char* const* requested_partitions, const char* ab_suffix, AvbSlotVerifyData* slot_data) { AvbSlotVerifyResult ret; uint8_t* image_buf = NULL; bool image_preloaded = false; size_t n; if (ops->get_size_of_partition == NULL) { avb_error("get_size_of_partition() not implemented.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT; goto out; } for (n = 0; requested_partitions[n] != NULL; n++) { char part_name[AVB_PART_NAME_MAX_SIZE]; AvbIOResult io_ret; uint64_t image_size; AvbPartitionData* loaded_partition; if (!avb_str_concat(part_name, sizeof part_name, requested_partitions[n], avb_strlen(requested_partitions[n]), ab_suffix, avb_strlen(ab_suffix))) { avb_error("Partition name and suffix does not fit.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } io_ret = ops->get_size_of_partition(ops, part_name, &image_size); if (io_ret == AVB_IO_RESULT_ERROR_OOM) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } else if (io_ret != AVB_IO_RESULT_OK) { avb_errorv(part_name, ": Error determining partition size.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; goto out; } avb_debugv(part_name, ": Loading entire partition.\n", NULL); ret = load_full_partition( ops, part_name, image_size, &image_buf, &image_preloaded); if (ret != AVB_SLOT_VERIFY_RESULT_OK) { goto out; } /* Move to slot_data. */ if (slot_data->num_loaded_partitions == MAX_NUMBER_OF_LOADED_PARTITIONS) { avb_errorv(part_name, ": Too many loaded partitions.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } loaded_partition = &slot_data->loaded_partitions[slot_data->num_loaded_partitions++]; loaded_partition->partition_name = avb_strdup(requested_partitions[n]); if (loaded_partition->partition_name == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } loaded_partition->data_size = image_size; loaded_partition->data = image_buf; /* Transferring the owner. */ loaded_partition->preloaded = image_preloaded; image_buf = NULL; image_preloaded = false; } ret = AVB_SLOT_VERIFY_RESULT_OK; out: /* Free the current buffer if any. */ if (image_buf != NULL && !image_preloaded) { avb_free(image_buf); } /* Buffers that are already saved in slot_data will be handled by the caller * even on failure. */ return ret; } static AvbSlotVerifyResult load_and_verify_vbmeta( AvbOps* ops, const char* const* requested_partitions, const char* ab_suffix, bool allow_verification_error, AvbVBMetaImageFlags toplevel_vbmeta_flags, int rollback_index_location, const char* partition_name, size_t partition_name_len, const uint8_t* expected_public_key, size_t expected_public_key_length, AvbSlotVerifyData* slot_data, AvbAlgorithmType* out_algorithm_type, AvbCmdlineSubstList* out_additional_cmdline_subst) { char full_partition_name[AVB_PART_NAME_MAX_SIZE]; AvbSlotVerifyResult ret; AvbIOResult io_ret; size_t vbmeta_offset; size_t vbmeta_size; uint8_t* vbmeta_buf = NULL; size_t vbmeta_num_read; AvbVBMetaVerifyResult vbmeta_ret; const uint8_t* pk_data; size_t pk_len; AvbVBMetaImageHeader vbmeta_header; uint64_t stored_rollback_index; const AvbDescriptor** descriptors = NULL; size_t num_descriptors; size_t n; bool is_main_vbmeta; bool is_vbmeta_partition; AvbVBMetaData* vbmeta_image_data = NULL; ret = AVB_SLOT_VERIFY_RESULT_OK; avb_assert(slot_data != NULL); /* Since we allow top-level vbmeta in 'boot', use * rollback_index_location to determine whether we're the main * vbmeta struct. */ is_main_vbmeta = (rollback_index_location == 0); is_vbmeta_partition = (avb_strcmp(partition_name, "vbmeta") == 0); if (!avb_validate_utf8((const uint8_t*)partition_name, partition_name_len)) { avb_error("Partition name is not valid UTF-8.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } /* Construct full partition name. */ if (!avb_str_concat(full_partition_name, sizeof full_partition_name, partition_name, partition_name_len, ab_suffix, avb_strlen(ab_suffix))) { avb_error("Partition name and suffix does not fit.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } avb_debugv("Loading vbmeta struct from partition '", full_partition_name, "'.\n", NULL); /* If we're loading from the main vbmeta partition, the vbmeta * struct is in the beginning. Otherwise we have to locate it via a * footer. */ if (is_vbmeta_partition) { vbmeta_offset = 0; vbmeta_size = VBMETA_MAX_SIZE; } else { uint8_t footer_buf[AVB_FOOTER_SIZE]; size_t footer_num_read; AvbFooter footer; io_ret = ops->read_from_partition(ops, full_partition_name, -AVB_FOOTER_SIZE, AVB_FOOTER_SIZE, footer_buf, &footer_num_read); if (io_ret == AVB_IO_RESULT_ERROR_OOM) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } else if (io_ret != AVB_IO_RESULT_OK) { avb_errorv(full_partition_name, ": Error loading footer.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; goto out; } avb_assert(footer_num_read == AVB_FOOTER_SIZE); if (!avb_footer_validate_and_byteswap((const AvbFooter*)footer_buf, &footer)) { avb_errorv(full_partition_name, ": Error validating footer.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } /* Basic footer sanity check since the data is untrusted. */ if (footer.vbmeta_size > VBMETA_MAX_SIZE) { avb_errorv( full_partition_name, ": Invalid vbmeta size in footer.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } vbmeta_offset = footer.vbmeta_offset; vbmeta_size = footer.vbmeta_size; } vbmeta_buf = avb_malloc(vbmeta_size); if (vbmeta_buf == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } io_ret = ops->read_from_partition(ops, full_partition_name, vbmeta_offset, vbmeta_size, vbmeta_buf, &vbmeta_num_read); if (io_ret == AVB_IO_RESULT_ERROR_OOM) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } else if (io_ret != AVB_IO_RESULT_OK) { /* If we're looking for 'vbmeta' but there is no such partition, * go try to get it from the boot partition instead. */ if (is_main_vbmeta && io_ret == AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION && is_vbmeta_partition) { avb_debugv(full_partition_name, ": No such partition. Trying 'boot' instead.\n", NULL); ret = load_and_verify_vbmeta(ops, requested_partitions, ab_suffix, allow_verification_error, 0 /* toplevel_vbmeta_flags */, 0 /* rollback_index_location */, "boot", avb_strlen("boot"), NULL /* expected_public_key */, 0 /* expected_public_key_length */, slot_data, out_algorithm_type, out_additional_cmdline_subst); goto out; } else { avb_errorv(full_partition_name, ": Error loading vbmeta data.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; goto out; } } avb_assert(vbmeta_num_read <= vbmeta_size); /* Check if the image is properly signed and get the public key used * to sign the image. */ vbmeta_ret = avb_vbmeta_image_verify(vbmeta_buf, vbmeta_num_read, &pk_data, &pk_len); switch (vbmeta_ret) { case AVB_VBMETA_VERIFY_RESULT_OK: avb_assert(pk_data != NULL && pk_len > 0); break; case AVB_VBMETA_VERIFY_RESULT_OK_NOT_SIGNED: case AVB_VBMETA_VERIFY_RESULT_HASH_MISMATCH: case AVB_VBMETA_VERIFY_RESULT_SIGNATURE_MISMATCH: ret = AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION; avb_errorv(full_partition_name, ": Error verifying vbmeta image: ", avb_vbmeta_verify_result_to_string(vbmeta_ret), "\n", NULL); if (!allow_verification_error) { goto out; } break; case AVB_VBMETA_VERIFY_RESULT_INVALID_VBMETA_HEADER: /* No way to continue this case. */ ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; avb_errorv(full_partition_name, ": Error verifying vbmeta image: invalid vbmeta header\n", NULL); goto out; case AVB_VBMETA_VERIFY_RESULT_UNSUPPORTED_VERSION: /* No way to continue this case. */ ret = AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION; avb_errorv(full_partition_name, ": Error verifying vbmeta image: unsupported AVB version\n", NULL); goto out; } /* Byteswap the header. */ avb_vbmeta_image_header_to_host_byte_order((AvbVBMetaImageHeader*)vbmeta_buf, &vbmeta_header); /* If we're the toplevel, assign flags so they'll be passed down. */ if (is_main_vbmeta) { toplevel_vbmeta_flags = (AvbVBMetaImageFlags)vbmeta_header.flags; } else { if (vbmeta_header.flags != 0) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; avb_errorv(full_partition_name, ": chained vbmeta image has non-zero flags\n", NULL); goto out; } } /* Check if key used to make signature matches what is expected. */ if (pk_data != NULL) { if (expected_public_key != NULL) { avb_assert(!is_main_vbmeta); if (expected_public_key_length != pk_len || avb_safe_memcmp(expected_public_key, pk_data, pk_len) != 0) { avb_errorv(full_partition_name, ": Public key used to sign data does not match key in chain " "partition descriptor.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED; if (!allow_verification_error) { goto out; } } } else { bool key_is_trusted = false; const uint8_t* pk_metadata = NULL; size_t pk_metadata_len = 0; if (vbmeta_header.public_key_metadata_size > 0) { pk_metadata = vbmeta_buf + sizeof(AvbVBMetaImageHeader) + vbmeta_header.authentication_data_block_size + vbmeta_header.public_key_metadata_offset; pk_metadata_len = vbmeta_header.public_key_metadata_size; } avb_assert(is_main_vbmeta); io_ret = ops->validate_vbmeta_public_key( ops, pk_data, pk_len, pk_metadata, pk_metadata_len, &key_is_trusted); if (io_ret == AVB_IO_RESULT_ERROR_OOM) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } else if (io_ret != AVB_IO_RESULT_OK) { avb_errorv(full_partition_name, ": Error while checking public key used to sign data.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; goto out; } if (!key_is_trusted) { avb_errorv(full_partition_name, ": Public key used to sign data rejected.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED; if (!allow_verification_error) { goto out; } } } } /* Check rollback index. */ io_ret = ops->read_rollback_index( ops, rollback_index_location, &stored_rollback_index); if (io_ret == AVB_IO_RESULT_ERROR_OOM) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } else if (io_ret != AVB_IO_RESULT_OK) { avb_errorv(full_partition_name, ": Error getting rollback index for location.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; goto out; } if (vbmeta_header.rollback_index < stored_rollback_index) { avb_errorv( full_partition_name, ": Image rollback index is less than the stored rollback index.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX; if (!allow_verification_error) { goto out; } } /* Copy vbmeta to vbmeta_images before recursing. */ if (is_main_vbmeta) { avb_assert(slot_data->num_vbmeta_images == 0); } else { avb_assert(slot_data->num_vbmeta_images > 0); } if (slot_data->num_vbmeta_images == MAX_NUMBER_OF_VBMETA_IMAGES) { avb_errorv(full_partition_name, ": Too many vbmeta images.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } vbmeta_image_data = &slot_data->vbmeta_images[slot_data->num_vbmeta_images++]; vbmeta_image_data->partition_name = avb_strdup(partition_name); vbmeta_image_data->vbmeta_data = vbmeta_buf; /* Note that |vbmeta_buf| is actually |vbmeta_num_read| bytes long * and this includes data past the end of the image. Pass the * actual size of the vbmeta image. Also, no need to use * avb_safe_add() since the header has already been verified. */ vbmeta_image_data->vbmeta_size = sizeof(AvbVBMetaImageHeader) + vbmeta_header.authentication_data_block_size + vbmeta_header.auxiliary_data_block_size; vbmeta_image_data->verify_result = vbmeta_ret; /* If verification has been disabled by setting a bit in the image, * we're done... except that we need to load the entirety of the * requested partitions. */ if (vbmeta_header.flags & AVB_VBMETA_IMAGE_FLAGS_VERIFICATION_DISABLED) { AvbSlotVerifyResult sub_ret; avb_debugv( full_partition_name, ": VERIFICATION_DISABLED bit is set.\n", NULL); /* If load_requested_partitions() fail it is always a fatal * failure (e.g. ERROR_INVALID_ARGUMENT, ERROR_OOM, etc.) rather * than recoverable (e.g. one where result_should_continue() * returns true) and we want to convey that error. */ sub_ret = load_requested_partitions( ops, requested_partitions, ab_suffix, slot_data); if (sub_ret != AVB_SLOT_VERIFY_RESULT_OK) { ret = sub_ret; } goto out; } /* Now go through all descriptors and take the appropriate action: * * - hash descriptor: Load data from partition, calculate hash, and * checks that it matches what's in the hash descriptor. * * - hashtree descriptor: Do nothing since verification happens * on-the-fly from within the OS. (Unless the descriptor uses a * persistent digest, in which case we need to find it). * * - chained partition descriptor: Load the footer, load the vbmeta * image, verify vbmeta image (includes rollback checks, hash * checks, bail on chained partitions). */ descriptors = avb_descriptor_get_all(vbmeta_buf, vbmeta_num_read, &num_descriptors); for (n = 0; n < num_descriptors; n++) { AvbDescriptor desc; if (!avb_descriptor_validate_and_byteswap(descriptors[n], &desc)) { avb_errorv(full_partition_name, ": Descriptor is invalid.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } switch (desc.tag) { case AVB_DESCRIPTOR_TAG_HASH: { AvbSlotVerifyResult sub_ret; sub_ret = load_and_verify_hash_partition(ops, requested_partitions, ab_suffix, allow_verification_error, descriptors[n], slot_data); if (sub_ret != AVB_SLOT_VERIFY_RESULT_OK) { ret = sub_ret; if (!allow_verification_error || !result_should_continue(ret)) { goto out; } } } break; case AVB_DESCRIPTOR_TAG_CHAIN_PARTITION: { AvbSlotVerifyResult sub_ret; AvbChainPartitionDescriptor chain_desc; const uint8_t* chain_partition_name; const uint8_t* chain_public_key; /* Only allow CHAIN_PARTITION descriptors in the main vbmeta image. */ if (!is_main_vbmeta) { avb_errorv(full_partition_name, ": Encountered chain descriptor not in main image.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } if (!avb_chain_partition_descriptor_validate_and_byteswap( (AvbChainPartitionDescriptor*)descriptors[n], &chain_desc)) { avb_errorv(full_partition_name, ": Chain partition descriptor is invalid.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } if (chain_desc.rollback_index_location == 0) { avb_errorv(full_partition_name, ": Chain partition has invalid " "rollback_index_location field.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } chain_partition_name = ((const uint8_t*)descriptors[n]) + sizeof(AvbChainPartitionDescriptor); chain_public_key = chain_partition_name + chain_desc.partition_name_len; sub_ret = load_and_verify_vbmeta(ops, requested_partitions, ab_suffix, allow_verification_error, toplevel_vbmeta_flags, chain_desc.rollback_index_location, (const char*)chain_partition_name, chain_desc.partition_name_len, chain_public_key, chain_desc.public_key_len, slot_data, NULL, /* out_algorithm_type */ NULL /* out_additional_cmdline_subst */); if (sub_ret != AVB_SLOT_VERIFY_RESULT_OK) { ret = sub_ret; if (!result_should_continue(ret)) { goto out; } } } break; case AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE: { const uint8_t* kernel_cmdline; AvbKernelCmdlineDescriptor kernel_cmdline_desc; bool apply_cmdline; if (!avb_kernel_cmdline_descriptor_validate_and_byteswap( (AvbKernelCmdlineDescriptor*)descriptors[n], &kernel_cmdline_desc)) { avb_errorv(full_partition_name, ": Kernel cmdline descriptor is invalid.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } kernel_cmdline = ((const uint8_t*)descriptors[n]) + sizeof(AvbKernelCmdlineDescriptor); if (!avb_validate_utf8(kernel_cmdline, kernel_cmdline_desc.kernel_cmdline_length)) { avb_errorv(full_partition_name, ": Kernel cmdline is not valid UTF-8.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } /* Compare the flags for top-level VBMeta struct with flags in * the command-line descriptor so command-line snippets only * intended for a certain mode (dm-verity enabled/disabled) * are skipped if applicable. */ apply_cmdline = true; if (toplevel_vbmeta_flags & AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED) { if (kernel_cmdline_desc.flags & AVB_KERNEL_CMDLINE_FLAGS_USE_ONLY_IF_HASHTREE_NOT_DISABLED) { apply_cmdline = false; } } else { if (kernel_cmdline_desc.flags & AVB_KERNEL_CMDLINE_FLAGS_USE_ONLY_IF_HASHTREE_DISABLED) { apply_cmdline = false; } } if (apply_cmdline) { if (slot_data->cmdline == NULL) { slot_data->cmdline = avb_calloc(kernel_cmdline_desc.kernel_cmdline_length + 1); if (slot_data->cmdline == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } avb_memcpy(slot_data->cmdline, kernel_cmdline, kernel_cmdline_desc.kernel_cmdline_length); } else { /* new cmdline is: + ' ' + + '\0' */ size_t orig_size = avb_strlen(slot_data->cmdline); size_t new_size = orig_size + 1 + kernel_cmdline_desc.kernel_cmdline_length + 1; char* new_cmdline = avb_calloc(new_size); if (new_cmdline == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto out; } avb_memcpy(new_cmdline, slot_data->cmdline, orig_size); new_cmdline[orig_size] = ' '; avb_memcpy(new_cmdline + orig_size + 1, kernel_cmdline, kernel_cmdline_desc.kernel_cmdline_length); avb_free(slot_data->cmdline); slot_data->cmdline = new_cmdline; } } } break; case AVB_DESCRIPTOR_TAG_HASHTREE: { AvbHashtreeDescriptor hashtree_desc; if (!avb_hashtree_descriptor_validate_and_byteswap( (AvbHashtreeDescriptor*)descriptors[n], &hashtree_desc)) { avb_errorv( full_partition_name, ": Hashtree descriptor is invalid.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } /* We only need to continue when there is no digest in the descriptor. * This is because the only processing here is to find the digest and * make it available on the kernel command line. */ if (hashtree_desc.root_digest_len == 0) { char part_name[AVB_PART_NAME_MAX_SIZE]; size_t digest_len = 0; uint8_t digest_buf[AVB_SHA512_DIGEST_SIZE]; const uint8_t* desc_partition_name = ((const uint8_t*)descriptors[n]) + sizeof(AvbHashtreeDescriptor); if (!avb_validate_utf8(desc_partition_name, hashtree_desc.partition_name_len)) { avb_error("Partition name is not valid UTF-8.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } /* No ab_suffix for partitions without a digest in the descriptor * because these partitions hold data unique to this device and are * not updated using an A/B scheme. */ if ((hashtree_desc.flags & AVB_HASHTREE_DESCRIPTOR_FLAGS_DO_NOT_USE_AB) == 0 && avb_strlen(ab_suffix) != 0) { avb_error("Cannot use A/B with a persistent root digest.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } if (hashtree_desc.partition_name_len >= AVB_PART_NAME_MAX_SIZE) { avb_error("Partition name does not fit.\n"); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } avb_memcpy( part_name, desc_partition_name, hashtree_desc.partition_name_len); part_name[hashtree_desc.partition_name_len] = '\0'; /* Determine the expected digest size from the hash algorithm. */ if (avb_strcmp((const char*)hashtree_desc.hash_algorithm, "sha1") == 0) { digest_len = AVB_SHA1_DIGEST_SIZE; } else if (avb_strcmp((const char*)hashtree_desc.hash_algorithm, "sha256") == 0) { digest_len = AVB_SHA256_DIGEST_SIZE; } else if (avb_strcmp((const char*)hashtree_desc.hash_algorithm, "sha512") == 0) { digest_len = AVB_SHA512_DIGEST_SIZE; } else { avb_errorv(part_name, ": Unsupported hash algorithm.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } ret = read_persistent_digest(ops, part_name, digest_len, digest_buf); if (ret != AVB_SLOT_VERIFY_RESULT_OK) { goto out; } if (out_additional_cmdline_subst) { ret = avb_add_root_digest_substitution(part_name, digest_buf, digest_len, out_additional_cmdline_subst); if (ret != AVB_SLOT_VERIFY_RESULT_OK) { goto out; } } } } break; case AVB_DESCRIPTOR_TAG_PROPERTY: /* Do nothing. */ break; } } if (rollback_index_location >= AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_LOCATIONS) { avb_errorv( full_partition_name, ": Invalid rollback_index_location.\n", NULL); ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; goto out; } slot_data->rollback_indexes[rollback_index_location] = vbmeta_header.rollback_index; if (out_algorithm_type != NULL) { *out_algorithm_type = (AvbAlgorithmType)vbmeta_header.algorithm_type; } out: /* If |vbmeta_image_data| isn't NULL it means that it adopted * |vbmeta_buf| so in that case don't free it here. */ if (vbmeta_image_data == NULL) { if (vbmeta_buf != NULL) { avb_free(vbmeta_buf); } } if (descriptors != NULL) { avb_free(descriptors); } return ret; } AvbSlotVerifyResult avb_slot_verify(AvbOps* ops, const char* const* requested_partitions, const char* ab_suffix, AvbSlotVerifyFlags flags, AvbHashtreeErrorMode hashtree_error_mode, AvbSlotVerifyData** out_data) { AvbSlotVerifyResult ret; AvbSlotVerifyData* slot_data = NULL; AvbAlgorithmType algorithm_type = AVB_ALGORITHM_TYPE_NONE; bool using_boot_for_vbmeta = false; AvbVBMetaImageHeader toplevel_vbmeta; bool allow_verification_error = (flags & AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR); AvbCmdlineSubstList* additional_cmdline_subst = NULL; /* Fail early if we're missing the AvbOps needed for slot verification. * * For now, handle get_size_of_partition() not being implemented. In * a later release we may change that. */ avb_assert(ops->read_is_device_unlocked != NULL); avb_assert(ops->read_from_partition != NULL); avb_assert(ops->validate_vbmeta_public_key != NULL); avb_assert(ops->read_rollback_index != NULL); avb_assert(ops->get_unique_guid_for_partition != NULL); if (out_data != NULL) { *out_data = NULL; } /* Allowing dm-verity errors defeats the purpose of verified boot so * only allow this if set up to allow verification errors * (e.g. typically only UNLOCKED mode). */ if (hashtree_error_mode == AVB_HASHTREE_ERROR_MODE_LOGGING && !allow_verification_error) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT; goto fail; } slot_data = avb_calloc(sizeof(AvbSlotVerifyData)); if (slot_data == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto fail; } slot_data->vbmeta_images = avb_calloc(sizeof(AvbVBMetaData) * MAX_NUMBER_OF_VBMETA_IMAGES); if (slot_data->vbmeta_images == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto fail; } slot_data->loaded_partitions = avb_calloc(sizeof(AvbPartitionData) * MAX_NUMBER_OF_LOADED_PARTITIONS); if (slot_data->loaded_partitions == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto fail; } additional_cmdline_subst = avb_new_cmdline_subst_list(); if (additional_cmdline_subst == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto fail; } ret = load_and_verify_vbmeta(ops, requested_partitions, ab_suffix, allow_verification_error, 0 /* toplevel_vbmeta_flags */, 0 /* rollback_index_location */, "vbmeta", avb_strlen("vbmeta"), NULL /* expected_public_key */, 0 /* expected_public_key_length */, slot_data, &algorithm_type, additional_cmdline_subst); if (!allow_verification_error && ret != AVB_SLOT_VERIFY_RESULT_OK) { goto fail; } /* If things check out, mangle the kernel command-line as needed. */ if (result_should_continue(ret)) { if (avb_strcmp(slot_data->vbmeta_images[0].partition_name, "vbmeta") != 0) { avb_assert( avb_strcmp(slot_data->vbmeta_images[0].partition_name, "boot") == 0); using_boot_for_vbmeta = true; } /* Byteswap top-level vbmeta header since we'll need it below. */ avb_vbmeta_image_header_to_host_byte_order( (const AvbVBMetaImageHeader*)slot_data->vbmeta_images[0].vbmeta_data, &toplevel_vbmeta); /* Fill in |ab_suffix| field. */ slot_data->ab_suffix = avb_strdup(ab_suffix); if (slot_data->ab_suffix == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto fail; } /* If verification is disabled, we are done ... we specifically * don't want to add any androidboot.* options since verification * is disabled. */ if (toplevel_vbmeta.flags & AVB_VBMETA_IMAGE_FLAGS_VERIFICATION_DISABLED) { /* Since verification is disabled we didn't process any * descriptors and thus there's no cmdline... so set root= such * that the system partition is mounted. */ avb_assert(slot_data->cmdline == NULL); slot_data->cmdline = avb_strdup("root=PARTUUID=$(ANDROID_SYSTEM_PARTUUID)"); if (slot_data->cmdline == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto fail; } } else { /* Add options - any failure in avb_append_options() is either an * I/O or OOM error. */ AvbSlotVerifyResult sub_ret = avb_append_options(ops, slot_data, &toplevel_vbmeta, algorithm_type, hashtree_error_mode); if (sub_ret != AVB_SLOT_VERIFY_RESULT_OK) { ret = sub_ret; goto fail; } } /* Substitute $(ANDROID_SYSTEM_PARTUUID) and friends. */ if (slot_data->cmdline != NULL) { char* new_cmdline; new_cmdline = avb_sub_cmdline(ops, slot_data->cmdline, ab_suffix, using_boot_for_vbmeta, additional_cmdline_subst); if (new_cmdline != slot_data->cmdline) { if (new_cmdline == NULL) { ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; goto fail; } avb_free(slot_data->cmdline); slot_data->cmdline = new_cmdline; } } if (out_data != NULL) { *out_data = slot_data; } else { avb_slot_verify_data_free(slot_data); } } avb_free_cmdline_subst_list(additional_cmdline_subst); additional_cmdline_subst = NULL; if (!allow_verification_error) { avb_assert(ret == AVB_SLOT_VERIFY_RESULT_OK); } return ret; fail: if (slot_data != NULL) { avb_slot_verify_data_free(slot_data); } if (additional_cmdline_subst != NULL) { avb_free_cmdline_subst_list(additional_cmdline_subst); } return ret; } void avb_slot_verify_data_free(AvbSlotVerifyData* data) { if (data->ab_suffix != NULL) { avb_free(data->ab_suffix); } if (data->cmdline != NULL) { avb_free(data->cmdline); } if (data->vbmeta_images != NULL) { size_t n; for (n = 0; n < data->num_vbmeta_images; n++) { AvbVBMetaData* vbmeta_image = &data->vbmeta_images[n]; if (vbmeta_image->partition_name != NULL) { avb_free(vbmeta_image->partition_name); } if (vbmeta_image->vbmeta_data != NULL) { avb_free(vbmeta_image->vbmeta_data); } } avb_free(data->vbmeta_images); } if (data->loaded_partitions != NULL) { size_t n; for (n = 0; n < data->num_loaded_partitions; n++) { AvbPartitionData* loaded_partition = &data->loaded_partitions[n]; if (loaded_partition->partition_name != NULL) { avb_free(loaded_partition->partition_name); } if (loaded_partition->data != NULL && !loaded_partition->preloaded) { avb_free(loaded_partition->data); } } avb_free(data->loaded_partitions); } avb_free(data); } const char* avb_slot_verify_result_to_string(AvbSlotVerifyResult result) { const char* ret = NULL; switch (result) { case AVB_SLOT_VERIFY_RESULT_OK: ret = "OK"; break; case AVB_SLOT_VERIFY_RESULT_ERROR_OOM: ret = "ERROR_OOM"; break; case AVB_SLOT_VERIFY_RESULT_ERROR_IO: ret = "ERROR_IO"; break; case AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION: ret = "ERROR_VERIFICATION"; break; case AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX: ret = "ERROR_ROLLBACK_INDEX"; break; case AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED: ret = "ERROR_PUBLIC_KEY_REJECTED"; break; case AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA: ret = "ERROR_INVALID_METADATA"; break; case AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION: ret = "ERROR_UNSUPPORTED_VERSION"; break; case AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT: ret = "ERROR_INVALID_ARGUMENT"; break; /* Do not add a 'default:' case here because of -Wswitch. */ } if (ret == NULL) { avb_error("Unknown AvbSlotVerifyResult value.\n"); ret = "(unknown)"; } return ret; } void avb_slot_verify_data_calculate_vbmeta_digest(AvbSlotVerifyData* data, AvbDigestType digest_type, uint8_t* out_digest) { bool ret = false; size_t n; switch (digest_type) { case AVB_DIGEST_TYPE_SHA256: { AvbSHA256Ctx ctx; avb_sha256_init(&ctx); for (n = 0; n < data->num_vbmeta_images; n++) { avb_sha256_update(&ctx, data->vbmeta_images[n].vbmeta_data, data->vbmeta_images[n].vbmeta_size); } avb_memcpy(out_digest, avb_sha256_final(&ctx), AVB_SHA256_DIGEST_SIZE); ret = true; } break; case AVB_DIGEST_TYPE_SHA512: { AvbSHA512Ctx ctx; avb_sha512_init(&ctx); for (n = 0; n < data->num_vbmeta_images; n++) { avb_sha512_update(&ctx, data->vbmeta_images[n].vbmeta_data, data->vbmeta_images[n].vbmeta_size); } avb_memcpy(out_digest, avb_sha512_final(&ctx), AVB_SHA512_DIGEST_SIZE); ret = true; } break; /* Do not add a 'default:' case here because of -Wswitch. */ } if (!ret) { avb_fatal("Unknown digest type"); } }