[PATCH v2 1/4] tpm: fix: keep auth session intact after unseal operation

Jarkko Sakkinen
2016-02-13T13:47:29Z

The behavior of policy based unseal operation is not consistent:

* When there is an error in TPM2_Unseal operation, the session object
stays in the TPM transient memory.
* When the unseal is succesful, the TPM automatically removes the
session object.

This patch sets the continueSession attribute to keep the session intact
after a successful unseal operation thus making the behavior consistent.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Fixes: 5beb0c435b ("keys, trusted: seal with a TPM2 authorization policy")
---
drivers/char/tpm/tpm2-cmd.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 66e04b4..b28e4da 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -20,7 +20,11 @@
#include <keys/trusted-type.h>

enum tpm2_object_attributes {
- TPM2_ATTR_USER_WITH_AUTH = BIT(6),
+ TPM2_OA_USER_WITH_AUTH = BIT(6),
+};
+
+enum tpm2_session_attributes {
+ TPM2_SA_CONTINUE_SESSION = BIT(0),
};

struct tpm2_startup_in {
@@ -489,7 +493,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
tpm_buf_append(&buf, options->policydigest,
options->policydigest_len);
} else {
- tpm_buf_append_u32(&buf, TPM2_ATTR_USER_WITH_AUTH);
+ tpm_buf_append_u32(&buf, TPM2_OA_USER_WITH_AUTH);
tpm_buf_append_u16(&buf, 0);
}

@@ -627,7 +631,7 @@ static int tpm2_unseal(struct tpm_chip *chip,
options->policyhandle ?
options->policyhandle : TPM2_RS_PW,
NULL /* nonce */, 0,
- 0 /* session_attributes */,
+ TPM2_SA_CONTINUE_SESSION,
options->blobauth /* hmac */,
TPM_DIGEST_SIZE);

--
2.7.0