[U-Boot] [RFC PATCH] cmd: avb: Support A/B slots

[Sam Protsenko]

Hi Igor, Jens,

Can you please comments on next topics:
  1. With enabled A/B partitions, we have boot_a/boot_b,
     system_a/system_b, vendor_a/vendor_b partitions. Therefore
     requested_partitions[] should be slotted (which is done in this RFC
     patch). But this patch doesn' handle item (2) below.
  2. With dynamic partitions enabled, we don't have system/vendor
     anymore; instead we have single "super" partitions. Therefore
     requested_partitions[] table contains wrong partitions list for
     that particular case.

Question: can we allow user to select which partition to verify, instead
of trying to verify hard-coded partitions from requested_partitions[]
table? This would solve both (1) and (2) items. But I'm not sure about
next possible issues:
  a. Wouldn't it break chain of trust somehow?
  b. Is it ok to run avb_slot_verify() several times (one time per one
     partition?

If (a) or (b) is of any concern, then maybe we can provide a way for the
user to pass any number of arguments to 'avb verify', like this:

    => avb verify boot_a super_a dtbo_a

so help synopsis for 'avb verify' can be like this:

    avb verify <partition> ...

What do you think about this? Which would be the best course of action
to fix both issues (1) and (2)?

Thanks.

Signed-off-by: Sam Protsenko <semen.protsenko at linaro.org>
---
 cmd/avb.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/cmd/avb.c b/cmd/avb.c
index 3f6fd763a0..d1942d6605 100644
--- a/cmd/avb.c
+++ b/cmd/avb.c
@@ -235,6 +235,7 @@ int do_avb_verify_part(cmd_tbl_t *cmdtp, int flag,
 	AvbSlotVerifyData *out_data;
 	char *cmdline;
 	char *extra_args;
+	char *slot_suffix = "";
 
 	bool unlocked = false;
 	int res = CMD_RET_FAILURE;
@@ -244,9 +245,12 @@ int do_avb_verify_part(cmd_tbl_t *cmdtp, int flag,
 		return CMD_RET_FAILURE;
 	}
 
-	if (argc != 1)
+	if (argc < 1 || argc > 2)
 		return CMD_RET_USAGE;
 
+	if (argc == 2)
+		slot_suffix = argv[1];
+
 	printf("## Android Verified Boot 2.0 version %s\n",
 	       avb_version_string());
 
@@ -259,7 +263,7 @@ int do_avb_verify_part(cmd_tbl_t *cmdtp, int flag,
 	slot_result =
 		avb_slot_verify(avb_ops,
 				requested_partitions,
-				"",
+				slot_suffix,
 				unlocked,
 				AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE,
 				&out_data);
@@ -419,7 +423,7 @@ static cmd_tbl_t cmd_avb[] = {
 	U_BOOT_CMD_MKENT(read_part, 5, 0, do_avb_read_part, "", ""),
 	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, "", ""),
+	U_BOOT_CMD_MKENT(verify, 2, 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, "", ""),
@@ -462,6 +466,7 @@ U_BOOT_CMD(
 	"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"
+	"avb verify [slot_suffix] - run verification process using hash data\n"
 	"    from vbmeta structure\n"
+	"    [slot_suffix] - _a, _b, etc (if vbmeta partition is slotted)\n"
 	);
-- 
2.20.1