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systemd/SOURCES/0618-tpm2-handle-older-tpm-...

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From 9935268b03aa24fbf0e70eaa42ee58db94f237d3 Mon Sep 17 00:00:00 2001
From: Dan Streetman <ddstreet@ieee.org>
Date: Fri, 14 Jul 2023 13:15:48 -0400
Subject: [PATCH] tpm2: handle older tpm enrollments without a saved pcr bank
Older code did not save the pcr bank (i.e. pcr hash algorithm), and instead let
tpm2_unseal() find the best pcr bank to use. In commit
2cd9d57548b0dadd52523df486d33aa4cf7c3b84 we changed tpm2_unseal() to no longer
handle an unset pcr bank. This adds back in the handling of an unset pcr_bank
so older sealed data should continue to work.
(cherry picked from commit 730d6ab9302f42a2d49355ec8851bd5e3929b36d)
Related: RHEL-16182
---
src/shared/tpm2-util.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/src/shared/tpm2-util.c b/src/shared/tpm2-util.c
index ffadfa1498..e743dad392 100644
--- a/src/shared/tpm2-util.c
+++ b/src/shared/tpm2-util.c
@@ -4078,6 +4078,14 @@ int tpm2_unseal(const char *device,
if (r < 0)
return r;
+ /* Older code did not save the pcr_bank, and unsealing needed to detect the best pcr bank to use,
+ * so we need to handle that legacy situation. */
+ if (pcr_bank == UINT16_MAX) {
+ r = tpm2_get_best_pcr_bank(c, hash_pcr_mask|pubkey_pcr_mask, &pcr_bank);
+ if (r < 0)
+ return r;
+ }
+
_cleanup_(tpm2_handle_freep) Tpm2Handle *primary_handle = NULL;
if (srk_buf) {
r = tpm2_deserialize(c, srk_buf, srk_buf_size, &primary_handle);