ta: avb: add support for named persistent values

Introduce support for named persistent values [1], that are mainly used
to store persistent digests.

Link: [1] https://android.googlesource.com/platform/external/avb/+/master/README.md#Named-Persistent-Values

Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Igor Opaniuk <igor.opaniuk@linaro.org>

2 files changed, 154 insertions, 15 deletions

diff --git a/ta/avb/entry.c b/ta/avb/entry.c
index 2e22518d..8f69e155 100644
--- a/ta/avb/entry.c
+++ b/ta/avb/entry.c
@@ -5,10 +5,14 @@
 #include <tee_internal_api.h>
 #include <tee_internal_api_extensions.h>
 
+#include <string.h>
+#include <util.h>
+
 #define DEFAULT_LOCK_STATE	0
 
 static const uint32_t storageid = TEE_STORAGE_PRIVATE_RPMB;
-static const char obj_name[] = "rb_state";
+static const char rb_obj_name[] = "rb_state";
+static const char *named_value_prefix = "named_value_";
 
 static TEE_Result get_slot_offset(size_t slot, size_t *offset)
 {
@@ -19,28 +23,51 @@ static TEE_Result get_slot_offset(size_t slot, size_t *offset)
 	return TEE_SUCCESS;
 }
 
-static TEE_Result create_state(uint32_t lock_state, TEE_ObjectHandle *h)
+static TEE_Result create_rb_state(uint32_t lock_state, TEE_ObjectHandle *h)
 {
 	const uint32_t flags = TEE_DATA_FLAG_ACCESS_READ |
 			       TEE_DATA_FLAG_ACCESS_WRITE |
 			       TEE_DATA_FLAG_OVERWRITE;
 
-	return TEE_CreatePersistentObject(storageid, obj_name, sizeof(obj_name),
-					  flags, NULL, &lock_state,
-					  sizeof(lock_state), h);
+	return TEE_CreatePersistentObject(storageid, rb_obj_name,
+					  sizeof(rb_obj_name), flags, NULL,
+					  &lock_state, sizeof(lock_state), h);
 }
 
-static TEE_Result open_state(uint32_t default_lock_state, TEE_ObjectHandle *h)
+static TEE_Result open_rb_state(uint32_t default_lock_state,
+				TEE_ObjectHandle *h)
 {
-	uint32_t flags = TEE_DATA_FLAG_ACCESS_READ | TEE_DATA_FLAG_ACCESS_WRITE;
+	uint32_t flags = TEE_DATA_FLAG_ACCESS_READ |
+			 TEE_DATA_FLAG_ACCESS_WRITE;
 	TEE_Result res;
 
-	res = TEE_OpenPersistentObject(storageid, obj_name,
-				       sizeof(obj_name), flags, h);
+	res = TEE_OpenPersistentObject(storageid, rb_obj_name,
+				       sizeof(rb_obj_name), flags, h);
 	if (!res)
 		return TEE_SUCCESS;
 
-	return create_state(default_lock_state, h);
+	return create_rb_state(default_lock_state, h);
+}
+
+static TEE_Result get_named_object_name(char *name_orig,
+					uint32_t name_orig_size,
+					char *name, uint32_t *name_size)
+{
+	size_t pref_len = strlen(named_value_prefix);
+
+	if (name_orig_size + pref_len >
+	    TEE_OBJECT_ID_MAX_LEN)
+		return TEE_ERROR_BAD_PARAMETERS;
+
+	/* Start with prefix */
+	TEE_MemMove(name, named_value_prefix, pref_len);
+
+	/* Concatenate provided object name */
+	TEE_MemMove(name + pref_len, name_orig, name_orig_size);
+
+	*name_size = name_orig_size + pref_len;
+
+	return TEE_SUCCESS;
 }
 
 static TEE_Result read_rb_idx(uint32_t pt, TEE_Param params[TEE_NUM_PARAMS])
@@ -62,7 +89,7 @@ static TEE_Result read_rb_idx(uint32_t pt, TEE_Param params[TEE_NUM_PARAMS])
 	if (res)
 		return res;
 
-	res = open_state(DEFAULT_LOCK_STATE, &h);
+	res = open_rb_state(DEFAULT_LOCK_STATE, &h);
 	if (res)
 		return res;
 
@@ -119,7 +146,7 @@ static TEE_Result write_rb_idx(uint32_t pt, TEE_Param params[TEE_NUM_PARAMS])
 		return res;
 	widx = ((uint64_t)params[1].value.a << 32) | params[1].value.b;
 
-	res = open_state(DEFAULT_LOCK_STATE, &h);
+	res = open_rb_state(DEFAULT_LOCK_STATE, &h);
 	if (res)
 		return res;
 
@@ -162,7 +189,7 @@ static TEE_Result read_lock_state(uint32_t pt, TEE_Param params[TEE_NUM_PARAMS])
 	if (pt != exp_pt)
 		return TEE_ERROR_BAD_PARAMETERS;
 
-	res = open_state(DEFAULT_LOCK_STATE, &h);
+	res = open_rb_state(DEFAULT_LOCK_STATE, &h);
 	if (res)
 		return res;
 
@@ -202,7 +229,7 @@ static TEE_Result write_lock_state(uint32_t pt,
 
 	wlock_state = params[0].value.a;
 
-	res = open_state(wlock_state, &h);
+	res = open_rb_state(wlock_state, &h);
 	if (res)
 		return res;
 
@@ -212,9 +239,101 @@ static TEE_Result write_lock_state(uint32_t pt,
 	if (count == sizeof(lock_state) && lock_state == wlock_state)
 		goto out;
 
-	res = create_state(wlock_state, &h);
+	res = create_rb_state(wlock_state, &h);
+out:
+	TEE_CloseObject(h);
+	return res;
+}
+
+static TEE_Result write_persist_value(uint32_t pt,
+				      TEE_Param params[TEE_NUM_PARAMS])
+{
+	const uint32_t exp_pt = TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_INPUT,
+						TEE_PARAM_TYPE_MEMREF_INPUT,
+						TEE_PARAM_TYPE_NONE,
+						TEE_PARAM_TYPE_NONE);
+	const uint32_t flags = TEE_DATA_FLAG_ACCESS_READ |
+			       TEE_DATA_FLAG_ACCESS_WRITE |
+			       TEE_DATA_FLAG_OVERWRITE;
+	TEE_Result res;
+	TEE_ObjectHandle h;
+
+	char name_full[TEE_OBJECT_ID_MAX_LEN];
+	uint32_t name_full_sz;
+
+	if (pt != exp_pt)
+		return TEE_ERROR_BAD_PARAMETERS;
+
+	char *name_buf = params[0].memref.buffer;
+	uint32_t name_buf_sz = params[0].memref.size;
+
+	char *value = params[1].memref.buffer;
+	uint32_t value_sz = params[1].memref.size;
+
+	res = get_named_object_name(name_buf, name_buf_sz,
+				    name_full, &name_full_sz);
+	if (res)
+		return res;
+
+	res = TEE_CreatePersistentObject(storageid, name_full,
+					 name_full_sz,
+					 flags, NULL, value,
+					 value_sz, &h);
+	if (res)
+		EMSG("Can't create named object value, res = 0x%x", res);
+
+	TEE_CloseObject(h);
+
+	return res;
+}
+
+static TEE_Result read_persist_value(uint32_t pt,
+				      TEE_Param params[TEE_NUM_PARAMS])
+{
+	const uint32_t exp_pt = TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_INPUT,
+						TEE_PARAM_TYPE_MEMREF_INOUT,
+						TEE_PARAM_TYPE_NONE,
+						TEE_PARAM_TYPE_NONE);
+	uint32_t flags = TEE_DATA_FLAG_ACCESS_READ |
+			 TEE_DATA_FLAG_ACCESS_WRITE;
+	TEE_Result res;
+	TEE_ObjectHandle h;
+
+	char name_full[TEE_OBJECT_ID_MAX_LEN];
+	uint32_t name_full_sz;
+	uint32_t count;
+
+	if (pt != exp_pt)
+		return TEE_ERROR_BAD_PARAMETERS;
+
+	char *name_buf = params[0].memref.buffer;
+	uint32_t name_buf_sz = params[0].memref.size;
+
+	char *value = params[1].memref.buffer;
+	uint32_t value_sz = params[1].memref.size;
+
+	res = get_named_object_name(name_buf, name_buf_sz,
+				    name_full, &name_full_sz);
+	if (res)
+		return res;
+
+	res = TEE_OpenPersistentObject(storageid, name_full,
+				       name_full_sz, flags, &h);
+	if (res) {
+		EMSG("Can't open named object value, res = 0x%x", res);
+		return res;
+	}
+
+	res =  TEE_ReadObjectData(h, value, value_sz, &count);
+	if (res) {
+		EMSG("Can't read named object value, res = 0x%x", res);
+		goto out;
+	}
+
+	params[1].memref.size = count;
 out:
 	TEE_CloseObject(h);
+
 	return res;
 }
 
@@ -251,6 +370,10 @@ TEE_Result TA_InvokeCommandEntryPoint(void *sess __unused, uint32_t cmd,
 		return read_lock_state(pt, params);
 	case TA_AVB_CMD_WRITE_LOCK_STATE:
 		return write_lock_state(pt, params);
+	case TA_AVB_CMD_READ_PERSIST_VALUE:
+		return read_persist_value(pt, params);
+	case TA_AVB_CMD_WRITE_PERSIST_VALUE:
+		return write_persist_value(pt, params);
 	default:
 		EMSG("Command ID 0x%x is not supported", cmd);
 		return TEE_ERROR_NOT_SUPPORTED;
diff --git a/ta/avb/include/ta_avb.h b/ta/avb/include/ta_avb.h
index 0e1da084..45521f75 100644
--- a/ta/avb/include/ta_avb.h
+++ b/ta/avb/include/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].memref:	persistent value name
+ * out	params[1].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].memref:	persistent value name
+ * in	params[1].memref:	persistent value buffer to write
+ */
+#define TA_AVB_CMD_WRITE_PERSIST_VALUE	5
+
 #endif /*__TA_AVB_H*/