[PATCH] efi_loader: accept append write with valid size and data

[Masahisa Kojima]

Current "variables" efi_selftest result is inconsistent
between the U-Boot file storage and the tee-based StandaloneMM
RPMB secure storage.
U-Boot file storage implementation does not accept SetVariale
call to non-existent variable with EFI_VARIABLE_APPEND_WRITE
attribute and valid size and data, however it is accepted
in EDK II StandaloneMM implementation.

Since UEFI specification does not clearly describe the behavior
of the append write to non-existent variable, let's update
the U-Boot file storage implementation to get aligned with
the EDK II reference implementation.

Signed-off-by: Masahisa Kojima <kojima.masahisa at socionext.com>
---
 lib/efi_loader/efi_variable.c             | 13 +++++-----
 lib/efi_selftest/efi_selftest_variables.c | 30 +++++++++++++++++++++--
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index 40f7a0fb10..1693c3387b 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -282,11 +282,8 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
 		}
 		time = var->time;
 	} else {
-		if (delete || append)
-			/*
-			 * Trying to delete or to update a non-existent
-			 * variable.
-			 */
+		if (delete)
+			/* Trying to delete a non-existent variable. */
 			return EFI_NOT_FOUND;
 	}
 
@@ -329,7 +326,11 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
 		/* EFI_NOT_FOUND has been handled before */
 		attributes = var->attr;
 		ret = EFI_SUCCESS;
-	} else if (append) {
+	} else if (append && var) {
+		/*
+		 * data is appended if EFI_VARIABLE_APPEND_WRITE is set and
+		 * variable exists.
+		 */
 		u16 *old_data = var->name;
 
 		for (; *old_data; ++old_data)
diff --git a/lib/efi_selftest/efi_selftest_variables.c b/lib/efi_selftest/efi_selftest_variables.c
index c7a3fdbaa6..0c2c76599e 100644
--- a/lib/efi_selftest/efi_selftest_variables.c
+++ b/lib/efi_selftest/efi_selftest_variables.c
@@ -131,13 +131,39 @@ static int execute(void)
 			    (unsigned int)len);
 	if (memcmp(data, v, len))
 		efi_st_todo("GetVariable returned wrong value\n");
-	/* Append variable 2 */
+	/* Append variable 2, write to non-existent variable */
 	ret = runtime->set_variable(u"efi_none", &guid_vendor1,
 				    EFI_VARIABLE_BOOTSERVICE_ACCESS |
 				    EFI_VARIABLE_APPEND_WRITE,
 				    15, v);
+	if (ret != EFI_SUCCESS) {
+		efi_st_error("SetVariable(APPEND_WRITE) with valid size and data to non-existent variable must be succcessful\n");
+		return EFI_ST_FAILURE;
+	}
+	len = EFI_ST_MAX_DATA_SIZE;
+	ret = runtime->get_variable(u"efi_none", &guid_vendor1,
+				    &attr, &len, data);
+	if (ret != EFI_SUCCESS) {
+		efi_st_error("GetVariable failed\n");
+		return EFI_ST_FAILURE;
+	}
+	if (len != 15)
+		efi_st_todo("GetVariable returned wrong length %u\n",
+			    (unsigned int)len);
+	if (memcmp(data, v, len))
+		efi_st_todo("GetVariable returned wrong value\n");
+	/* Delete variable efi_none */
+	ret = runtime->set_variable(u"efi_none", &guid_vendor1,
+				    0, 0, NULL);
+	if (ret != EFI_SUCCESS) {
+		efi_st_error("SetVariable failed\n");
+		return EFI_ST_FAILURE;
+	}
+	len = EFI_ST_MAX_DATA_SIZE;
+	ret = runtime->get_variable(u"efi_none", &guid_vendor1,
+				    &attr, &len, data);
 	if (ret != EFI_NOT_FOUND) {
-		efi_st_error("SetVariable(APPEND_WRITE) with size 0 to non-existent variable returns wrong code\n");
+		efi_st_error("Variable was not deleted\n");
 		return EFI_ST_FAILURE;
 	}
 	/* Enumerate variables */
-- 
2.34.1