linux-kernel - [PATCH v2] KEYS: trusted: tpm2: Fix migratable logic

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Date:   Tue, 07 Jun 2022 14:07:57 -0400
From:   david.safford@...il.com
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Ahmad Fatoum <a.fatoum@...gutronix.de>,
        James Bottomley <jejb@...ux.ibm.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        David Howells <dhowells@...hat.com>,
        James Morris <jmorris@...ei.org>,
        "SergeE.Hallyn" <serge@...lyn.com>
Cc:     linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] KEYS: trusted: tpm2: Fix migratable logic

When creating (sealing) a new trusted key, migratable
trusted keys have the FIXED_TPM and FIXED_PARENT attributes
set, and non-migratable keys don't. This is backwards, and
also causes creation to fail when creating a migratable key
under a migratable parent. (The TPM thinks you are trying to
seal a non-migratable blob under a migratable parent.)

The following simple patch fixes the logic, and has been
tested for all four combinations of migratable and non-migratable
trusted keys and parent storage keys. With this logic, you will
get a proper failure if you try to create a non-migratable
trusted key under a migratable parent storage key, and all other
combinations work correctly.

Fixes: e5fb5d2c5a03 ("security: keys: trusted: Make sealed key properly interoperable")
Signed-off-by: David Safford <david.safford@...il.com>
---
Changelog:
 * v2:
   * added Signed-off-by, Fixes, proper Subject and distribution
.
 security/keys/trusted-keys/trusted_tpm2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 0165da386289..2b2c8eb258d5 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -283,8 +283,8 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	/* key properties */
 	flags = 0;
 	flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
-	flags |= payload->migratable ? (TPM2_OA_FIXED_TPM |
-					TPM2_OA_FIXED_PARENT) : 0;
+	flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM |
+					    TPM2_OA_FIXED_PARENT);
 	tpm_buf_append_u32(&buf, flags);

 	/* policy */
--
2.36.1