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>

1 files changed, 78 insertions, 0 deletions

diff --git a/cmd/avb.c b/cmd/avb.c
index ff00be4cee..c5af4a2e46 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"
 	);