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android / platform / external / avb / fa354e62fb3f9ab9de6241c1accf56e12672c523 / . / libavb / avb_slot_verify.c
blob: 0d75210fa70c82dca652ae52e9b17d8b3616b533 [file] [log] [blame]
/*
* 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_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)
static AvbSlotVerifyResult initialize_persistent_digest(
AvbOps* ops,
const char* part_name,
const char* persistent_value_name,
size_t digest_size,
const uint8_t* initial_digest,
uint8_t* out_digest);
/* 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;
}
/* Reads a persistent digest stored as a named persistent value corresponding to
* the given |part_name|. The value is returned in |out_digest| which must point
* to |expected_digest_size| bytes. If there is no digest stored for |part_name|
* it can be initialized by providing a non-NULL |initial_digest| of length
* |expected_digest_size|. This automatic initialization will only occur if the
* device is currently locked. The |initial_digest| may be NULL.
*
* Returns AVB_SLOT_VERIFY_RESULT_OK on success, otherwise returns an
* AVB_SLOT_VERIFY_RESULT_ERROR_* error code.
*
* If the value does not exist, is not supported, or is not populated, and
* |initial_digest| is NULL, returns
* AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA. If |expected_digest_size| does
* not match the stored digest size, also returns
* AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA.
*/
static AvbSlotVerifyResult read_persistent_digest(AvbOps* ops,
const char* part_name,
size_t expected_digest_size,
const uint8_t* initial_digest,
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);
// If no such named persistent value exists and an initial digest value was
// given, initialize the named persistent value with the given digest. If
// initialized successfully, this will recurse into this function but with a
// NULL initial_digest.
if (io_ret == AVB_IO_RESULT_ERROR_NO_SUCH_VALUE && initial_digest) {
AvbSlotVerifyResult ret =
initialize_persistent_digest(ops,
part_name,
persistent_value_name,
expected_digest_size,
initial_digest,
out_digest);
avb_free(persistent_value_name);
return ret;
}
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) {
// Treat a missing persistent value as a verification error, which is
// ignoreable, rather than a metadata error which is not.
avb_errorv(part_name, ": Persistent digest does not exist.\n", NULL);
return AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION;
} else if (io_ret == AVB_IO_RESULT_ERROR_INVALID_VALUE_SIZE ||
io_ret == AVB_IO_RESULT_ERROR_INSUFFICIENT_SPACE) {
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;
} else if (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;
}
return AVB_SLOT_VERIFY_RESULT_OK;
}
static AvbSlotVerifyResult initialize_persistent_digest(
AvbOps* ops,
const char* part_name,
const char* persistent_value_name,
size_t digest_size,
const uint8_t* initial_digest,
uint8_t* out_digest) {
AvbSlotVerifyResult ret;
AvbIOResult io_ret = AVB_IO_RESULT_OK;
bool is_device_unlocked = true;
io_ret = ops->read_is_device_unlocked(ops, &is_device_unlocked);
if (io_ret == AVB_IO_RESULT_ERROR_OOM) {
return AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
} else if (io_ret != AVB_IO_RESULT_OK) {
avb_error("Error getting device lock state.\n");
return AVB_SLOT_VERIFY_RESULT_ERROR_IO;
}
if (is_device_unlocked) {
avb_debugv(part_name,
": Digest does not exist, device unlocked so not initializing "
"digest.\n",
NULL);
return AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION;
}
// Device locked; initialize digest with given initial value.
avb_debugv(part_name,
": Digest does not exist, initializing persistent digest.\n",
NULL);
io_ret = ops->write_persistent_value(
ops, persistent_value_name, digest_size, initial_digest);
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 initializing persistent digest.\n", NULL);
return AVB_SLOT_VERIFY_RESULT_ERROR_IO;
}
// To ensure that the digest value was written successfully - and avoid a
// scenario where the digest is simply 'initialized' on every verify - recurse
// into read_persistent_digest to read back the written value. The NULL
// initial_digest ensures that this will not recurse again.
ret = read_persistent_digest(ops, part_name, digest_size, NULL, out_digest);
if (ret != AVB_SLOT_VERIFY_RESULT_OK) {
avb_errorv(part_name,
": Reading back initialized persistent digest failed!\n",
NULL);
}
return ret;
}
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) {
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;
}
// Although only one of the type might be used, we have to defined the
// structure here so that they would live outside the 'if/else' scope to be
// used later.
AvbSHA256Ctx sha256_ctx;
AvbSHA512Ctx sha512_ctx;
size_t image_size_to_hash = hash_desc.image_size;
// If we allow verification error and the whole partition is smaller than
// image size in hash descriptor, we just hash the whole partition.
if (image_size_to_hash > image_size) {
image_size_to_hash = image_size;
}
if (avb_strcmp((const char*)hash_desc.hash_algorithm, "sha256") == 0) {
avb_sha256_init(&sha256_ctx);
avb_sha256_update(&sha256_ctx, desc_salt, hash_desc.salt_len);
avb_sha256_update(&sha256_ctx, image_buf, image_size_to_hash);
digest = avb_sha256_final(&sha256_ctx);
digest_len = AVB_SHA256_DIGEST_SIZE;
} else if (avb_strcmp((const char*)hash_desc.hash_algorithm, "sha512") == 0) {
avb_sha512_init(&sha512_ctx);
avb_sha512_update(&sha512_ctx, desc_salt, hash_desc.salt_len);
avb_sha512_update(&sha512_ctx, image_buf, image_size_to_hash);
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));
/* Pass |digest| as the |initial_digest| so devices not yet initialized get
* initialized to the current partition digest.
*/
ret = read_persistent_digest(
ops, part_name, digest_len, digest, 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;
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,
AvbSlotVerifyFlags flags,
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;
uint64_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 look_for_vbmeta_footer;
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 = false;
if (rollback_index_location == 0) {
if ((flags & AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION) == 0) {
is_main_vbmeta = true;
}
}
/* Don't use footers for vbmeta partitions ('vbmeta' or
* 'vbmeta_<partition_name>').
*/
look_for_vbmeta_footer = true;
if (avb_strncmp(partition_name, "vbmeta", avb_strlen("vbmeta")) == 0) {
look_for_vbmeta_footer = false;
}
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 e.g. system_a. */
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;
}
/* If we're loading from the main vbmeta partition, the vbmeta struct is in
* the beginning. Otherwise we may have to locate it via a footer... if no
* footer is found, we look in the beginning to support e.g. vbmeta_<org>
* partitions holding data for e.g. super partitions (b/80195851 for
* rationale).
*/
vbmeta_offset = 0;
vbmeta_size = VBMETA_MAX_SIZE;
if (look_for_vbmeta_footer) {
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_debugv(full_partition_name, ": No footer detected.\n", NULL);
} else {
/* 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);
} else {
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;
}
if (vbmeta_offset != 0) {
avb_debugv("Loading vbmeta struct in footer from partition '",
full_partition_name,
"'.\n",
NULL);
} else {
avb_debugv("Loading vbmeta struct from partition '",
full_partition_name,
"'.\n",
NULL);
}
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 &&
!look_for_vbmeta_footer) {
avb_debugv(full_partition_name,
": No such partition. Trying 'boot' instead.\n",
NULL);
ret = load_and_verify_vbmeta(ops,
requested_partitions,
ab_suffix,
flags,
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;
}
}
uint32_t rollback_index_location_to_use = rollback_index_location;
/* 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;
}
// If we're not using a vbmeta partition, need to use another AvbOps...
if (flags & AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION) {
io_ret = ops->validate_public_key_for_partition(
ops,
full_partition_name,
pk_data,
pk_len,
pk_metadata,
pk_metadata_len,
&key_is_trusted,
&rollback_index_location_to_use);
} else {
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_to_use, &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 {
if (!(flags & AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION)) {
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,
flags,
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: <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;
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,
NULL /* initial_digest */,
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 < 0 ||
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;
}
static AvbIOResult avb_manage_hashtree_error_mode(
AvbOps* ops,
AvbSlotVerifyFlags flags,
AvbSlotVerifyData* data,
AvbHashtreeErrorMode* out_hashtree_error_mode) {
AvbHashtreeErrorMode ret = AVB_HASHTREE_ERROR_MODE_RESTART;
AvbIOResult io_ret = AVB_IO_RESULT_OK;
uint8_t vbmeta_digest_sha256[AVB_SHA256_DIGEST_SIZE];
uint8_t stored_vbmeta_digest_sha256[AVB_SHA256_DIGEST_SIZE];
size_t num_bytes_read;
avb_assert(out_hashtree_error_mode != NULL);
avb_assert(ops->read_persistent_value != NULL);
avb_assert(ops->write_persistent_value != NULL);
// If we're rebooting because of dm-verity corruption, make a note of
// the vbmeta hash so we can stay in 'eio' mode until things change.
if (flags & AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION) {
avb_debug(
"Rebooting because of dm-verity corruption - "
"recording OS instance and using 'eio' mode.\n");
avb_slot_verify_data_calculate_vbmeta_digest(
data, AVB_DIGEST_TYPE_SHA256, vbmeta_digest_sha256);
io_ret = ops->write_persistent_value(ops,
AVB_NPV_MANAGED_VERITY_MODE,
AVB_SHA256_DIGEST_SIZE,
vbmeta_digest_sha256);
if (io_ret != AVB_IO_RESULT_OK) {
avb_error("Error writing to " AVB_NPV_MANAGED_VERITY_MODE ".\n");
goto out;
}
ret = AVB_HASHTREE_ERROR_MODE_EIO;
io_ret = AVB_IO_RESULT_OK;
goto out;
}
// See if we're in 'eio' mode.
io_ret = ops->read_persistent_value(ops,
AVB_NPV_MANAGED_VERITY_MODE,
AVB_SHA256_DIGEST_SIZE,
stored_vbmeta_digest_sha256,
&num_bytes_read);
if (io_ret == AVB_IO_RESULT_ERROR_NO_SUCH_VALUE ||
(io_ret == AVB_IO_RESULT_OK && num_bytes_read == 0)) {
// This is the usual case ('eio' mode not set).
avb_debug("No dm-verity corruption - using in 'restart' mode.\n");
ret = AVB_HASHTREE_ERROR_MODE_RESTART;
io_ret = AVB_IO_RESULT_OK;
goto out;
} else if (io_ret != AVB_IO_RESULT_OK) {
avb_error("Error reading from " AVB_NPV_MANAGED_VERITY_MODE ".\n");
goto out;
}
if (num_bytes_read != AVB_SHA256_DIGEST_SIZE) {
avb_error(
"Unexpected number of bytes read from " AVB_NPV_MANAGED_VERITY_MODE
".\n");
io_ret = AVB_IO_RESULT_ERROR_IO;
goto out;
}
// OK, so we're currently in 'eio' mode and the vbmeta digest of the OS
// that caused this is in |stored_vbmeta_digest_sha256| ... now see if
// the OS we're dealing with now is the same.
avb_slot_verify_data_calculate_vbmeta_digest(
data, AVB_DIGEST_TYPE_SHA256, vbmeta_digest_sha256);
if (avb_memcmp(vbmeta_digest_sha256,
stored_vbmeta_digest_sha256,
AVB_SHA256_DIGEST_SIZE) == 0) {
// It's the same so we're still in 'eio' mode.
avb_debug("Same OS instance detected - staying in 'eio' mode.\n");
ret = AVB_HASHTREE_ERROR_MODE_EIO;
io_ret = AVB_IO_RESULT_OK;
} else {
// It did change!
avb_debug(
"New OS instance detected - changing from 'eio' to 'restart' mode.\n");
io_ret =
ops->write_persistent_value(ops,
AVB_NPV_MANAGED_VERITY_MODE,
0, // This clears the persistent property.
vbmeta_digest_sha256);
if (io_ret != AVB_IO_RESULT_OK) {
avb_error("Error clearing " AVB_NPV_MANAGED_VERITY_MODE ".\n");
goto out;
}
ret = AVB_HASHTREE_ERROR_MODE_RESTART;
io_ret = AVB_IO_RESULT_OK;
}
out:
*out_hashtree_error_mode = ret;
return io_ret;
}
static bool has_system_partition(AvbOps* ops, const char* ab_suffix) {
char part_name[AVB_PART_NAME_MAX_SIZE];
char* system_part_name = "system";
char guid_buf[37];
AvbIOResult io_ret;
if (!avb_str_concat(part_name,
sizeof part_name,
system_part_name,
avb_strlen(system_part_name),
ab_suffix,
avb_strlen(ab_suffix))) {
avb_error("System partition name and suffix does not fit.\n");
return false;
}
io_ret = ops->get_unique_guid_for_partition(
ops, part_name, guid_buf, sizeof guid_buf);
if (io_ret == AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION) {
avb_debug("No system partition.\n");
return false;
} else if (io_ret != AVB_IO_RESULT_OK) {
avb_error("Error getting unique GUID for system partition.\n");
return false;
}
return true;
}
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. */
avb_assert(ops->read_is_device_unlocked != NULL);
avb_assert(ops->read_from_partition != NULL);
avb_assert(ops->get_size_of_partition != 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;
}
/* Make sure passed-in AvbOps support persistent values if
* asking for libavb to manage verity state.
*/
if (hashtree_error_mode == AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO) {
if (ops->read_persistent_value == NULL ||
ops->write_persistent_value == NULL) {
avb_error(
"Persistent values required for "
"AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO "
"but are not implemented in given AvbOps.\n");
ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT;
goto fail;
}
}
/* Make sure passed-in AvbOps support verifying public keys and getting
* rollback index location if not using a vbmeta partition.
*/
if (flags & AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION) {
if (ops->validate_public_key_for_partition == NULL) {
avb_error(
"AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION was passed but the "
"validate_public_key_for_partition() operation isn't implemented.\n");
ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT;
goto fail;
}
} else {
avb_assert(ops->validate_vbmeta_public_key != 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;
}
additional_cmdline_subst = avb_new_cmdline_subst_list();
if (additional_cmdline_subst == NULL) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto fail;
}
if (flags & AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION) {
if (requested_partitions == NULL || requested_partitions[0] == NULL) {
avb_fatal(
"Requested partitions cannot be empty when using "
"AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION");
ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT;
goto fail;
}
/* No vbmeta partition, go through each of the requested partitions... */
for (size_t n = 0; requested_partitions[n] != NULL; n++) {
ret = load_and_verify_vbmeta(ops,
requested_partitions,
ab_suffix,
flags,
allow_verification_error,
0 /* toplevel_vbmeta_flags */,
0 /* rollback_index_location */,
requested_partitions[n],
avb_strlen(requested_partitions[n]),
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;
}
}
} else {
/* Usual path, load "vbmeta"... */
ret = load_and_verify_vbmeta(ops,
requested_partitions,
ab_suffix,
flags,
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 (!result_should_continue(ret)) {
goto fail;
}
/* If things check out, mangle the kernel command-line as needed. */
if (!(flags & AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION)) {
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);
// Devices with dynamic partitions won't have system partition.
// Instead, it has a large super partition to accommodate *.img files.
// See b/119551429 for details.
if (has_system_partition(ops, ab_suffix)) {
slot_data->cmdline =
avb_strdup("root=PARTUUID=$(ANDROID_SYSTEM_PARTUUID)");
} else {
// The |cmdline| field should be a NUL-terminated string.
slot_data->cmdline = avb_strdup("");
}
if (slot_data->cmdline == NULL) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
goto fail;
}
} else {
/* If requested, manage dm-verity mode... */
AvbHashtreeErrorMode resolved_hashtree_error_mode = hashtree_error_mode;
if (hashtree_error_mode ==
AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO) {
AvbIOResult io_ret;
io_ret = avb_manage_hashtree_error_mode(
ops, flags, slot_data, &resolved_hashtree_error_mode);
if (io_ret != AVB_IO_RESULT_OK) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO;
if (io_ret == AVB_IO_RESULT_ERROR_OOM) {
ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM;
}
goto fail;
}
}
slot_data->resolved_hashtree_error_mode = resolved_hashtree_error_mode;
/* Add options... */
AvbSlotVerifyResult sub_ret;
sub_ret = avb_append_options(ops,
flags,
slot_data,
&toplevel_vbmeta,
algorithm_type,
hashtree_error_mode,
resolved_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 && avb_strlen(slot_data->cmdline) != 0) {
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");
}
}