/*
* Copyright (C) 2016 The Android Open Source Project
*
* 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 "avb_slot_verify.h"
#include "avb_chain_partition_descriptor.h"
#include "avb_footer.h"
#include "avb_hash_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 allow length (in bytes) of a partition name, including
* ab_suffix.
*/
#define PART_NAME_MAX_SIZE 32
/* 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:
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_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[PART_NAME_MAX_SIZE];
AvbSlotVerifyResult ret;
AvbIOResult io_ret;
uint8_t* image_buf = NULL;
size_t part_num_read;
uint8_t* digest;
size_t digest_len;
const char* found;
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;
}
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;
}
image_buf = avb_malloc(hash_desc.image_size);
if (image_buf == NULL) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto out;
}
io_ret = ops->read_from_partition(ops,
part_name,
0 /* offset */,
hash_desc.image_size,
image_buf,
&part_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(part_name, ": Error loading data from partition.\n", NULL);
ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO;
goto out;
}
if (part_num_read != hash_desc.image_size) {
avb_errorv(part_name, ": Read fewer than requested bytes.\n", NULL);
ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO;
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 (digest_len != hash_desc.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, desc_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 (ret == AVB_SLOT_VERIFY_RESULT_OK || result_should_continue(ret)) {
/* If this is the requested partition, copy to slot_data. */
found = avb_strv_find_str(requested_partitions,
(const char*)desc_partition_name,
hash_desc.partition_name_len);
if (found != 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 = hash_desc.image_size;
loaded_partition->data = image_buf;
image_buf = NULL;
}
}
fail:
if (image_buf != NULL) {
avb_free(image_buf);
}
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) {
char full_partition_name[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);
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;
/* 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.
*
* - 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 */);
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: <existing_cmdline> + ' ' + <newcmdline> + '\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;
/* Explicit fall-through */
case AVB_DESCRIPTOR_TAG_PROPERTY:
case AVB_DESCRIPTOR_TAG_HASHTREE:
/* 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;
}
#define NUM_GUIDS 3
/* Substitutes all variables (e.g. $(ANDROID_SYSTEM_PARTUUID)) with
* values. Returns NULL on OOM, otherwise the cmdline with values
* replaced.
*/
static char* sub_cmdline(AvbOps* ops,
const char* cmdline,
const char* ab_suffix,
bool using_boot_for_vbmeta) {
const char* part_name_str[NUM_GUIDS] = {"system", "boot", "vbmeta"};
const char* replace_str[NUM_GUIDS] = {"$(ANDROID_SYSTEM_PARTUUID)",
"$(ANDROID_BOOT_PARTUUID)",
"$(ANDROID_VBMETA_PARTUUID)"};
char* ret = NULL;
AvbIOResult io_ret;
/* Special-case for when the top-level vbmeta struct is in the boot
* partition.
*/
if (using_boot_for_vbmeta) {
part_name_str[2] = "boot";
}
/* Replace unique partition GUIDs */
for (size_t n = 0; n < NUM_GUIDS; n++) {
char part_name[PART_NAME_MAX_SIZE];
char guid_buf[37];
if (!avb_str_concat(part_name,
sizeof part_name,
part_name_str[n],
avb_strlen(part_name_str[n]),
ab_suffix,
avb_strlen(ab_suffix))) {
avb_error("Partition name and suffix does not fit.\n");
goto fail;
}
io_ret = ops->get_unique_guid_for_partition(
ops, part_name, guid_buf, sizeof guid_buf);
if (io_ret == AVB_IO_RESULT_ERROR_OOM) {
return NULL;
} else if (io_ret != AVB_IO_RESULT_OK) {
avb_error("Error getting unique GUID for partition.\n");
goto fail;
}
if (ret == NULL) {
ret = avb_replace(cmdline, replace_str[n], guid_buf);
} else {
char* new_ret = avb_replace(ret, replace_str[n], guid_buf);
avb_free(ret);
ret = new_ret;
}
if (ret == NULL) {
goto fail;
}
}
return ret;
fail:
if (ret != NULL) {
avb_free(ret);
}
return NULL;
}
static int cmdline_append_option(AvbSlotVerifyData* slot_data,
const char* key,
const char* value) {
size_t offset, key_len, value_len;
char* new_cmdline;
key_len = avb_strlen(key);
value_len = avb_strlen(value);
offset = 0;
if (slot_data->cmdline != NULL) {
offset = avb_strlen(slot_data->cmdline);
if (offset > 0) {
offset += 1;
}
}
new_cmdline = avb_calloc(offset + key_len + value_len + 2);
if (new_cmdline == NULL) {
return 0;
}
if (offset > 0) {
avb_memcpy(new_cmdline, slot_data->cmdline, offset - 1);
new_cmdline[offset - 1] = ' ';
}
avb_memcpy(new_cmdline + offset, key, key_len);
new_cmdline[offset + key_len] = '=';
avb_memcpy(new_cmdline + offset + key_len + 1, value, value_len);
if (slot_data->cmdline != NULL) {
avb_free(slot_data->cmdline);
}
slot_data->cmdline = new_cmdline;
return 1;
}
#define AVB_MAX_DIGITS_UINT64 32
/* Writes |value| to |digits| in base 10 followed by a NUL byte.
* Returns number of characters written excluding the NUL byte.
*/
static size_t uint64_to_base10(uint64_t value,
char digits[AVB_MAX_DIGITS_UINT64]) {
char rev_digits[AVB_MAX_DIGITS_UINT64];
size_t n, num_digits;
for (num_digits = 0; num_digits < AVB_MAX_DIGITS_UINT64 - 1;) {
rev_digits[num_digits++] = (value % 10) + '0';
value /= 10;
if (value == 0) {
break;
}
}
for (n = 0; n < num_digits; n++) {
digits[n] = rev_digits[num_digits - 1 - n];
}
digits[n] = '\0';
return n;
}
static int cmdline_append_version(AvbSlotVerifyData* slot_data,
const char* key,
uint64_t major_version,
uint64_t minor_version) {
char major_digits[AVB_MAX_DIGITS_UINT64];
char minor_digits[AVB_MAX_DIGITS_UINT64];
char combined[AVB_MAX_DIGITS_UINT64 * 2 + 1];
size_t num_major_digits, num_minor_digits;
num_major_digits = uint64_to_base10(major_version, major_digits);
num_minor_digits = uint64_to_base10(minor_version, minor_digits);
avb_memcpy(combined, major_digits, num_major_digits);
combined[num_major_digits] = '.';
avb_memcpy(combined + num_major_digits + 1, minor_digits, num_minor_digits);
combined[num_major_digits + 1 + num_minor_digits] = '\0';
return cmdline_append_option(slot_data, key, combined);
}
static int cmdline_append_uint64_base10(AvbSlotVerifyData* slot_data,
const char* key,
uint64_t value) {
char digits[AVB_MAX_DIGITS_UINT64];
uint64_to_base10(value, digits);
return cmdline_append_option(slot_data, key, digits);
}
static int cmdline_append_hex(AvbSlotVerifyData* slot_data,
const char* key,
const uint8_t* data,
size_t data_len) {
char hex_digits[17] = "0123456789abcdef";
char* hex_data;
int ret;
size_t n;
hex_data = avb_malloc(data_len * 2 + 1);
if (hex_data == NULL) {
return 0;
}
for (n = 0; n < data_len; n++) {
hex_data[n * 2] = hex_digits[data[n] >> 4];
hex_data[n * 2 + 1] = hex_digits[data[n] & 0x0f];
}
hex_data[n * 2] = '\0';
ret = cmdline_append_option(slot_data, key, hex_data);
avb_free(hex_data);
return ret;
}
AvbSlotVerifyResult avb_slot_verify(AvbOps* ops,
const char* const* requested_partitions,
const char* ab_suffix,
bool allow_verification_error,
AvbSlotVerifyData** out_data) {
AvbSlotVerifyResult ret;
AvbSlotVerifyData* slot_data = NULL;
AvbAlgorithmType algorithm_type = AVB_ALGORITHM_TYPE_NONE;
AvbIOResult io_ret;
bool using_boot_for_vbmeta = false;
if (out_data != NULL) {
*out_data = NULL;
}
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;
}
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);
if (!allow_verification_error && ret != AVB_SLOT_VERIFY_RESULT_OK) {
goto fail;
}
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;
}
/* If things check out, mangle the kernel command-line as needed. */
if (result_should_continue(ret)) {
/* 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;
}
/* Add androidboot.vbmeta.device option. */
if (!cmdline_append_option(slot_data,
"androidboot.vbmeta.device",
"PARTUUID=$(ANDROID_VBMETA_PARTUUID)")) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto fail;
}
/* Add androidboot.vbmeta.avb_version option. */
if (!cmdline_append_version(slot_data,
"androidboot.vbmeta.avb_version",
AVB_VERSION_MAJOR,
AVB_VERSION_MINOR)) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto fail;
}
/* Substitute $(ANDROID_SYSTEM_PARTUUID) and friends. */
if (slot_data->cmdline != NULL) {
char* new_cmdline;
new_cmdline = sub_cmdline(
ops, slot_data->cmdline, ab_suffix, using_boot_for_vbmeta);
if (new_cmdline == NULL) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto fail;
}
avb_free(slot_data->cmdline);
slot_data->cmdline = new_cmdline;
}
/* Set androidboot.avb.device_state to "locked" or "unlocked". */
bool is_device_unlocked;
io_ret = ops->read_is_device_unlocked(ops, &is_device_unlocked);
if (io_ret == AVB_IO_RESULT_ERROR_OOM) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto fail;
} else if (io_ret != AVB_IO_RESULT_OK) {
avb_error("Error getting device state.\n");
ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO;
goto fail;
}
if (!cmdline_append_option(slot_data,
"androidboot.vbmeta.device_state",
is_device_unlocked ? "unlocked" : "locked")) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto fail;
}
/* Set androidboot.vbmeta.{hash_alg, size, digest} - use same hash
* function as is used to sign vbmeta.
*/
switch (algorithm_type) {
/* Explicit fallthrough. */
case AVB_ALGORITHM_TYPE_NONE:
case AVB_ALGORITHM_TYPE_SHA256_RSA2048:
case AVB_ALGORITHM_TYPE_SHA256_RSA4096:
case AVB_ALGORITHM_TYPE_SHA256_RSA8192: {
AvbSHA256Ctx ctx;
size_t n, total_size = 0;
avb_sha256_init(&ctx);
for (n = 0; n < slot_data->num_vbmeta_images; n++) {
avb_sha256_update(&ctx,
slot_data->vbmeta_images[n].vbmeta_data,
slot_data->vbmeta_images[n].vbmeta_size);
total_size += slot_data->vbmeta_images[n].vbmeta_size;
}
if (!cmdline_append_option(
slot_data, "androidboot.vbmeta.hash_alg", "sha256") ||
!cmdline_append_uint64_base10(
slot_data, "androidboot.vbmeta.size", total_size) ||
!cmdline_append_hex(slot_data,
"androidboot.vbmeta.digest",
avb_sha256_final(&ctx),
AVB_SHA256_DIGEST_SIZE)) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto fail;
}
} break;
/* Explicit fallthrough. */
case AVB_ALGORITHM_TYPE_SHA512_RSA2048:
case AVB_ALGORITHM_TYPE_SHA512_RSA4096:
case AVB_ALGORITHM_TYPE_SHA512_RSA8192: {
AvbSHA512Ctx ctx;
size_t n, total_size = 0;
avb_sha512_init(&ctx);
for (n = 0; n < slot_data->num_vbmeta_images; n++) {
avb_sha512_update(&ctx,
slot_data->vbmeta_images[n].vbmeta_data,
slot_data->vbmeta_images[n].vbmeta_size);
total_size += slot_data->vbmeta_images[n].vbmeta_size;
}
if (!cmdline_append_option(
slot_data, "androidboot.vbmeta.hash_alg", "sha512") ||
!cmdline_append_uint64_base10(
slot_data, "androidboot.vbmeta.size", total_size) ||
!cmdline_append_hex(slot_data,
"androidboot.vbmeta.digest",
avb_sha512_final(&ctx),
AVB_SHA512_DIGEST_SIZE)) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto fail;
}
} break;
case _AVB_ALGORITHM_NUM_TYPES:
avb_assert_not_reached();
break;
}
if (out_data != NULL) {
*out_data = slot_data;
} else {
avb_slot_verify_data_free(slot_data);
}
}
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);
}
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) {
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;
/* Do not add a 'default:' case here because of -Wswitch. */
}
if (ret == NULL) {
avb_error("Unknown AvbSlotVerifyResult value.\n");
ret = "(unknown)";
}
return ret;
}