avb: add support for named persistent values

AVB 2.0 spec. revision 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

Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Igor Opaniuk <igor.opaniuk@gmail.com>

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"
 	);

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;
 

drivers/tee/sandbox.c

@@ -14,6 +14,7 @@
  * available.
  */
 
+static const u32 pstorage_max = 16;
 /**
  * struct ta_entry - TA entries
  * @uuid:		UUID of an emulated TA
@@ -24,8 +25,11 @@
  */
 struct ta_entry {
 	struct tee_optee_ta_uuid uuid;
-	u32 (*open_session)(uint num_params, struct tee_param *params);
+	u32 (*open_session)(struct udevice *dev, uint num_params,
-	u32 (*invoke_func)(u32 func, uint num_params, struct tee_param *params);
+			    struct tee_param *params);
+	u32 (*invoke_func)(struct udevice *dev,
+			   u32 func, uint num_params,
+			   struct tee_param *params);
 };
 
 #ifdef CONFIG_OPTEE_TA_AVB
@@ -59,10 +63,8 @@ bad_params:
 	return TEE_ERROR_BAD_PARAMETERS;
 }
 
-static u64 ta_avb_rollback_indexes[TA_AVB_MAX_ROLLBACK_LOCATIONS];
+static u32 ta_avb_open_session(struct udevice *dev, uint num_params,
-static u32 ta_avb_lock_state;
+			       struct tee_param *params)
-
-static u32 ta_avb_open_session(uint num_params, struct tee_param *params)
 {
 	/*
 	 * We don't expect additional parameters when opening a session to
@@ -73,12 +75,17 @@ static u32 ta_avb_open_session(uint num_params, struct tee_param *params)
 			    num_params, params);
 }
 
-static u32 ta_avb_invoke_func(u32 func, uint num_params,
+static u32 ta_avb_invoke_func(struct udevice *dev, u32 func, uint num_params,
 			      struct tee_param *params)
 {
+	struct sandbox_tee_state *state = dev_get_priv(dev);
+	ENTRY e, *ep;
+	char *name;
 	u32 res;
 	uint slot;
 	u64 val;
+	char *value;
+	u32 value_sz;
 
 	switch (func) {
 	case TA_AVB_CMD_READ_ROLLBACK_INDEX:
@@ -91,12 +98,12 @@ static u32 ta_avb_invoke_func(u32 func, uint num_params,
 			return res;
 
 		slot = params[0].u.value.a;
-		if (slot >= ARRAY_SIZE(ta_avb_rollback_indexes)) {
+		if (slot >= ARRAY_SIZE(state->ta_avb_rollback_indexes)) {
 			printf("Rollback index slot out of bounds %u\n", slot);
 			return TEE_ERROR_BAD_PARAMETERS;
 		}
 
-		val = ta_avb_rollback_indexes[slot];
+		val = state->ta_avb_rollback_indexes[slot];
 		params[1].u.value.a = val >> 32;
 		params[1].u.value.b = val;
 		return TEE_SUCCESS;
@@ -111,16 +118,16 @@ static u32 ta_avb_invoke_func(u32 func, uint num_params,
 			return res;
 
 		slot = params[0].u.value.a;
-		if (slot >= ARRAY_SIZE(ta_avb_rollback_indexes)) {
+		if (slot >= ARRAY_SIZE(state->ta_avb_rollback_indexes)) {
 			printf("Rollback index slot out of bounds %u\n", slot);
 			return TEE_ERROR_BAD_PARAMETERS;
 		}
 
 		val = (u64)params[1].u.value.a << 32 | params[1].u.value.b;
-		if (val < ta_avb_rollback_indexes[slot])
+		if (val < state->ta_avb_rollback_indexes[slot])
 			return TEE_ERROR_SECURITY;
 
-		ta_avb_rollback_indexes[slot] = val;
+		state->ta_avb_rollback_indexes[slot] = val;
 		return TEE_SUCCESS;
 
 	case TA_AVB_CMD_READ_LOCK_STATE:
@@ -132,7 +139,7 @@ static u32 ta_avb_invoke_func(u32 func, uint num_params,
 		if (res)
 			return res;
 
-		params[0].u.value.a = ta_avb_lock_state;
+		params[0].u.value.a = state->ta_avb_lock_state;
 		return TEE_SUCCESS;
 
 	case TA_AVB_CMD_WRITE_LOCK_STATE:
@@ -144,13 +151,64 @@ static u32 ta_avb_invoke_func(u32 func, uint num_params,
 		if (res)
 			return res;
 
-		if (ta_avb_lock_state != params[0].u.value.a) {
+		if (state->ta_avb_lock_state != params[0].u.value.a) {
-			ta_avb_lock_state = params[0].u.value.a;
+			state->ta_avb_lock_state = params[0].u.value.a;
-			memset(ta_avb_rollback_indexes, 0,
+			memset(state->ta_avb_rollback_indexes, 0,
-			       sizeof(ta_avb_rollback_indexes));
+			       sizeof(state->ta_avb_rollback_indexes));
 		}
 
 		return TEE_SUCCESS;
+	case TA_AVB_CMD_READ_PERSIST_VALUE:
+		res = check_params(TEE_PARAM_ATTR_TYPE_MEMREF_INPUT,
+				   TEE_PARAM_ATTR_TYPE_MEMREF_INOUT,
+				   TEE_PARAM_ATTR_TYPE_NONE,
+				   TEE_PARAM_ATTR_TYPE_NONE,
+				   num_params, params);
+		if (res)
+			return res;
+
+		name = params[0].u.memref.shm->addr;
+
+		value = params[1].u.memref.shm->addr;
+		value_sz = params[1].u.memref.size;
+
+		e.key = name;
+		e.data = NULL;
+		hsearch_r(e, FIND, &ep, &state->pstorage_htab, 0);
+		if (!ep)
+			return TEE_ERROR_ITEM_NOT_FOUND;
+
+		value_sz = strlen(ep->data);
+		memcpy(value, ep->data, value_sz);
+
+		return TEE_SUCCESS;
+	case TA_AVB_CMD_WRITE_PERSIST_VALUE:
+		res = check_params(TEE_PARAM_ATTR_TYPE_MEMREF_INPUT,
+				   TEE_PARAM_ATTR_TYPE_MEMREF_INPUT,
+				   TEE_PARAM_ATTR_TYPE_NONE,
+				   TEE_PARAM_ATTR_TYPE_NONE,
+				   num_params, params);
+		if (res)
+			return res;
+
+		name = params[0].u.memref.shm->addr;
+
+		value = params[1].u.memref.shm->addr;
+		value_sz = params[1].u.memref.size;
+
+		e.key = name;
+		e.data = NULL;
+		hsearch_r(e, FIND, &ep, &state->pstorage_htab, 0);
+		if (ep)
+			hdelete_r(e.key, &state->pstorage_htab, 0);
+
+		e.key = name;
+		e.data = value;
+		hsearch_r(e, ENTER, &ep, &state->pstorage_htab, 0);
+		if (!ep)
+			return TEE_ERROR_OUT_OF_MEMORY;
+
+		return TEE_SUCCESS;
 
 	default:
 		return TEE_ERROR_NOT_SUPPORTED;
@@ -225,7 +283,7 @@ static int sandbox_tee_open_session(struct udevice *dev,
 		return 0;
 	}
 
-	arg->ret = ta->open_session(num_params, params);
+	arg->ret = ta->open_session(dev, num_params, params);
 	arg->ret_origin = TEE_ORIGIN_TRUSTED_APP;
 
 	if (!arg->ret) {
@@ -261,7 +319,7 @@ static int sandbox_tee_invoke_func(struct udevice *dev,
 		return -EINVAL;
 	}
 
-	arg->ret = ta->invoke_func(arg->func, num_params, params);
+	arg->ret = ta->invoke_func(dev, arg->func, num_params, params);
 	arg->ret_origin = TEE_ORIGIN_TRUSTED_APP;
 
 	return 0;
@@ -285,6 +343,29 @@ static int sandbox_tee_shm_unregister(struct udevice *dev, struct tee_shm *shm)
 	return 0;
 }
 
+static int sandbox_tee_remove(struct udevice *dev)
+{
+	struct sandbox_tee_state *state = dev_get_priv(dev);
+
+	hdestroy_r(&state->pstorage_htab);
+
+	return 0;
+}
+
+static int sandbox_tee_probe(struct udevice *dev)
+{
+	struct sandbox_tee_state *state = dev_get_priv(dev);
+	/*
+	 * With this hastable we emulate persistent storage,
+	 * which should contain persistent values
+	 * between different sessions/command invocations.
+	 */
+	if (!hcreate_r(pstorage_max, &state->pstorage_htab))
+		return TEE_ERROR_OUT_OF_MEMORY;
+
+	return 0;
+}
+
 static const struct tee_driver_ops sandbox_tee_ops = {
 	.get_version = sandbox_tee_get_version,
 	.open_session = sandbox_tee_open_session,
@@ -305,4 +386,6 @@ U_BOOT_DRIVER(sandbox_tee) = {
 	.of_match = sandbox_tee_match,
 	.ops = &sandbox_tee_ops,
 	.priv_auto_alloc_size = sizeof(struct sandbox_tee_state),
+	.probe = sandbox_tee_probe,
+	.remove = sandbox_tee_remove,
 };

include/sandboxtee.h

@@ -6,16 +6,25 @@
 #ifndef __SANDBOXTEE_H
 #define __SANDBOXTEE_H
 
+#include <search.h>
+#include <tee/optee_ta_avb.h>
+
 /**
  * struct sandbox_tee_state - internal state of the sandbox TEE
  * @session:			current open session
  * @num_shms:			number of registered shared memory objects
  * @ta:				Trusted Application of current session
+ * @ta_avb_rollback_indexes	TA avb rollback indexes storage
+ * @ta_avb_lock_state		TA avb lock state storage
+ * @pstorage_htab		named persistent values storage
  */
 struct sandbox_tee_state {
 	u32 session;
 	int num_shms;
 	void *ta;
+	u64 ta_avb_rollback_indexes[TA_AVB_MAX_ROLLBACK_LOCATIONS];
+	u32 ta_avb_lock_state;
+	struct hsearch_data pstorage_htab;
 };
 
 #endif /*__SANDBOXTEE_H*/

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

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 */

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'