AVB version 1.1 introduces support for named persistent values that must be tamper evident and allows AVB to store arbitrary key-value pairs [1].

Introduce implementation of two additional AVB operations read_persistent_value()/write_persistent_value() for retrieving/storing named persistent values.

Correspondent pull request in the OP-TEE OS project repo [2].

[1]: https://android.googlesource.com/platform/external/avb/+/android-9.0.0_r22 [2]: https://github.com/OP-TEE/optee_os/pull/2699

Signed-off-by: Igor Opaniuk igor.opaniuk@linaro.org ---

Changes in v3: - fix possible mem lick in avb_read_persistent/avb_write_persistent - added additional sanity checks - covered avb read_pvalue/write_pvalue commands with python tests

Changes in v2: - fix output format for avb read_pvalue/write_pvalue commands - fix issue with named value buffer size

cmd/avb.c | 78 ++++++++++++++++++++++++++++ common/avb_verify.c | 125 +++++++++++++++++++++++++++++++++++++++++++++ include/tee.h | 2 + include/tee/optee_ta_avb.h | 16 ++++++ test/py/tests/test_avb.py | 16 ++++++ 5 files changed, 237 insertions(+)

diff --git a/cmd/avb.c b/cmd/avb.c index ff00be4..c5af4a2 100644 --- a/cmd/avb.c +++ b/cmd/avb.c @@ -340,6 +340,76 @@ int do_avb_is_unlocked(cmd_tbl_t *cmdtp, int flag, return CMD_RET_FAILURE; }

+int do_avb_read_pvalue(cmd_tbl_t *cmdtp, int flag, int argc, + char * const argv[]) +{ + const char *name; + size_t bytes; + size_t bytes_read; + void *buffer; + char *endp; + + if (!avb_ops) { + printf("AVB 2.0 is not initialized, run 'avb init' first\n"); + return CMD_RET_FAILURE; + } + + if (argc != 3) + return CMD_RET_USAGE; + + name = argv[1]; + bytes = simple_strtoul(argv[2], &endp, 10); + if (*endp && *endp != '\n') + return CMD_RET_USAGE; + + buffer = malloc(bytes); + if (!buffer) + return CMD_RET_FAILURE; + + if (avb_ops->read_persistent_value(avb_ops, name, bytes, buffer, + &bytes_read) == AVB_IO_RESULT_OK) { + printf("Read %ld bytes, value = %s\n", bytes_read, + (char *)buffer); + free(buffer); + return CMD_RET_SUCCESS; + } + + printf("Failed to read persistent value\n"); + + free(buffer); + + return CMD_RET_FAILURE; +} + +int do_avb_write_pvalue(cmd_tbl_t *cmdtp, int flag, int argc, + char * const argv[]) +{ + const char *name; + const char *value; + + if (!avb_ops) { + printf("AVB 2.0 is not initialized, run 'avb init' first\n"); + return CMD_RET_FAILURE; + } + + if (argc != 3) + return CMD_RET_USAGE; + + name = argv[1]; + value = argv[2]; + + if (avb_ops->write_persistent_value(avb_ops, name, strlen(value) + 1, + (const uint8_t *)value) == + AVB_IO_RESULT_OK) { + printf("Wrote %ld bytes\n", strlen(value) + 1); + return CMD_RET_SUCCESS; + } + + printf("Failed to write persistent value\n"); + + return CMD_RET_FAILURE; +} + static cmd_tbl_t cmd_avb[] = { U_BOOT_CMD_MKENT(init, 2, 0, do_avb_init, "", ""), U_BOOT_CMD_MKENT(read_rb, 2, 0, do_avb_read_rb, "", ""), @@ -350,6 +420,10 @@ static cmd_tbl_t cmd_avb[] = { U_BOOT_CMD_MKENT(read_part_hex, 4, 0, do_avb_read_part_hex, "", ""), U_BOOT_CMD_MKENT(write_part, 5, 0, do_avb_write_part, "", ""), U_BOOT_CMD_MKENT(verify, 1, 0, do_avb_verify_part, "", ""), +#ifdef CONFIG_OPTEE_TA_AVB + U_BOOT_CMD_MKENT(read_pvalue, 3, 0, do_avb_read_pvalue, "", ""), + U_BOOT_CMD_MKENT(write_pvalue, 3, 0, do_avb_write_pvalue, "", ""), +#endif };

static int do_avb(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) @@ -384,6 +458,10 @@ U_BOOT_CMD( " partition <partname> and print to stdout\n" "avb write_part <partname> <offset> <num> <addr> - write <num> bytes to\n" " <partname> by <offset> using data from <addr>\n" +#ifdef CONFIG_OPTEE_TA_AVB + "avb read_pvalue <name> <bytes> - read a persistent value <name>\n" + "avb write_pvalue <name> <value> - write a persistent value <name>\n" +#endif "avb verify - run verification process using hash data\n" " from vbmeta structure\n" ); diff --git a/common/avb_verify.c b/common/avb_verify.c index a8c5a3e..584e235 100644 --- a/common/avb_verify.c +++ b/common/avb_verify.c @@ -647,6 +647,10 @@ static AvbIOResult invoke_func(struct AvbOpsData *ops_data, u32 func, return AVB_IO_RESULT_OK; case TEE_ERROR_OUT_OF_MEMORY: return AVB_IO_RESULT_ERROR_OOM; + case TEE_ERROR_STORAGE_NO_SPACE: + return AVB_IO_RESULT_ERROR_INSUFFICIENT_SPACE; + case TEE_ERROR_ITEM_NOT_FOUND: + return AVB_IO_RESULT_ERROR_NO_SUCH_VALUE; case TEE_ERROR_TARGET_DEAD: /* * The TA has paniced, close the session to reload the TA @@ -847,6 +851,123 @@ static AvbIOResult get_size_of_partition(AvbOps *ops, return AVB_IO_RESULT_OK; }

+static AvbIOResult read_persistent_value(AvbOps *ops, + const char *name, + size_t buffer_size, + u8 *out_buffer, + size_t *out_num_bytes_read) +{ + AvbIOResult rc; + struct tee_shm *shm_name; + struct tee_shm *shm_buf; + struct tee_param param[2]; + struct udevice *tee; + size_t name_size = strlen(name) + 1; + + if (get_open_session(ops->user_data)) + return AVB_IO_RESULT_ERROR_IO; + + tee = ((struct AvbOpsData *)ops->user_data)->tee; + + rc = tee_shm_alloc(tee, name_size, + TEE_SHM_ALLOC, &shm_name); + if (rc) + return AVB_IO_RESULT_ERROR_OOM; + + rc = tee_shm_alloc(tee, buffer_size, + TEE_SHM_ALLOC, &shm_buf); + if (rc) { + rc = AVB_IO_RESULT_ERROR_OOM; + goto free_name; + } + + memcpy(shm_name->addr, name, name_size); + + memset(param, 0, sizeof(param)); + param[0].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT; + param[0].u.memref.shm = shm_name; + param[0].u.memref.size = name_size;; + param[1].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT; + param[1].u.memref.shm = shm_buf; + param[1].u.memref.size = buffer_size; + + rc = invoke_func(ops->user_data, TA_AVB_CMD_READ_PERSIST_VALUE, + 2, param); + if (rc) + goto out; + + if (param[1].u.memref.size > buffer_size) { + rc = AVB_IO_RESULT_ERROR_NO_SUCH_VALUE; + goto out; + } + + *out_num_bytes_read = param[1].u.memref.size; + + memcpy(out_buffer, shm_buf->addr, *out_num_bytes_read); + +out: + tee_shm_free(shm_buf); +free_name: + tee_shm_free(shm_name); + + return rc; +} + +static AvbIOResult write_persistent_value(AvbOps *ops, + const char *name, + size_t value_size, + const u8 *value) +{ + AvbIOResult rc; + struct tee_shm *shm_name; + struct tee_shm *shm_buf; + struct tee_param param[2]; + struct udevice *tee; + size_t name_size = strlen(name) + 1; + + if (get_open_session(ops->user_data)) + return AVB_IO_RESULT_ERROR_IO; + + tee = ((struct AvbOpsData *)ops->user_data)->tee; + + if (!value_size) + return AVB_IO_RESULT_ERROR_NO_SUCH_VALUE; + + rc = tee_shm_alloc(tee, name_size, + TEE_SHM_ALLOC, &shm_name); + if (rc) + return AVB_IO_RESULT_ERROR_OOM; + + rc = tee_shm_alloc(tee, value_size, + TEE_SHM_ALLOC, &shm_buf); + if (rc) { + rc = AVB_IO_RESULT_ERROR_OOM; + goto free_name; + } + + memcpy(shm_name->addr, name, name_size); + memcpy(shm_buf->addr, value, value_size); + + memset(param, 0, sizeof(param)); + param[0].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT; + param[0].u.memref.shm = shm_name; + param[0].u.memref.size = name_size; + param[1].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT; + param[1].u.memref.shm = shm_buf; + param[1].u.memref.size = value_size; + + rc = invoke_func(ops->user_data, TA_AVB_CMD_WRITE_PERSIST_VALUE, + 2, param); + if (rc) + goto out; + +out: + tee_shm_free(shm_buf); +free_name: + tee_shm_free(shm_name); + + return rc; +} /** * ============================================================================ * AVB2.0 AvbOps alloc/initialisation/free @@ -870,6 +991,10 @@ AvbOps *avb_ops_alloc(int boot_device) ops_data->ops.read_is_device_unlocked = read_is_device_unlocked; ops_data->ops.get_unique_guid_for_partition = get_unique_guid_for_partition; +#ifdef CONFIG_OPTEE_TA_AVB + ops_data->ops.write_persistent_value = write_persistent_value; + ops_data->ops.read_persistent_value = read_persistent_value; +#endif ops_data->ops.get_size_of_partition = get_size_of_partition; ops_data->mmc_dev = boot_device;

diff --git a/include/tee.h b/include/tee.h index edd9f9b..02bcd9e 100644 --- a/include/tee.h +++ b/include/tee.h @@ -43,7 +43,9 @@ #define TEE_ERROR_COMMUNICATION 0xffff000e #define TEE_ERROR_SECURITY 0xffff000f #define TEE_ERROR_OUT_OF_MEMORY 0xffff000c +#define TEE_ERROR_OVERFLOW 0xffff300f #define TEE_ERROR_TARGET_DEAD 0xffff3024 +#define TEE_ERROR_STORAGE_NO_SPACE 0xffff3041

#define TEE_ORIGIN_COMMS 0x00000002 #define TEE_ORIGIN_TEE 0x00000003 diff --git a/include/tee/optee_ta_avb.h b/include/tee/optee_ta_avb.h index 074386a..949875a 100644 --- a/include/tee/optee_ta_avb.h +++ b/include/tee/optee_ta_avb.h @@ -45,4 +45,20 @@ */ #define TA_AVB_CMD_WRITE_LOCK_STATE 3

+/* + * Reads a persistent value corresponding to the given name. + * + * in params[0].u.memref: persistent value name + * out params[1].u.memref: read persistent value buffer + */ +#define TA_AVB_CMD_READ_PERSIST_VALUE 4 + +/* + * Writes a persistent value corresponding to the given name. + * + * in params[0].u.memref: persistent value name + * in params[1].u.memref: persistent value buffer to write + */ +#define TA_AVB_CMD_WRITE_PERSIST_VALUE 5 + #endif /* __TA_AVB_H */ diff --git a/test/py/tests/test_avb.py b/test/py/tests/test_avb.py index e70a010..2bb75ed 100644 --- a/test/py/tests/test_avb.py +++ b/test/py/tests/test_avb.py @@ -116,3 +116,19 @@ def test_avb_mmc_read(u_boot_console): response = u_boot_console.run_command('cmp 0x%x 0x%x 40' % (temp_addr, temp_addr2)) assert response.find('64 word') + + +@pytest.mark.buildconfigspec('cmd_avb') +@pytest.mark.buildconfigspec('optee_ta_avb') +def test_avb_persistent_values(u_boot_console): + """Test reading/writing persistent storage to avb + """ + + response = u_boot_console.run_command('avb init %s' % str(mmc_dev)) + assert response == '' + + response = u_boot_console.run_command('avb write_pvalue test value_value') + assert response == 'Wrote 12 bytes' + + response = u_boot_console.run_command('avb read_pvalue test 12') + assert response == 'Read 12 bytes, value = value_value'