If some entity is snooping the TPM bus, the can see the data going in
to be sealed and the data coming out as it is unsealed. Add parameter
and response encryption to these cases to ensure that no secrets are
leaked even if the bus is snooped.
As part of doing this conversion it was discovered that policy
sessions can't work with HMAC protected authority because of missing
pieces (the tpm Nonce). I've added code to work the same way as
before, which will result in potential authority exposure (while still
adding security for the command and the returned blob), and a fixme to
redo the API to get rid of this security hole.
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
---
security/keys/trusted-keys/trusted_tpm2.c | 81 ++++++++++++++++-------
1 file changed, 57 insertions(+), 24 deletions(-)
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 2b2c8eb258d5..006c419b89c6 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -230,6 +230,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
{
int blob_len = 0;
struct tpm_buf buf;
+ struct tpm2_auth *auth;
u32 hash;
u32 flags;
int i;
@@ -252,18 +253,19 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
if (rc)
return rc;
+ rc = tpm2_start_auth_session(chip, &auth);
+ if (rc)
+ goto out_put;
+
rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
if (rc) {
- tpm_put_ops(chip);
- return rc;
+ tpm2_end_auth_session(auth);
+ goto out_put;
}
- tpm_buf_append_u32(&buf, options->keyhandle);
- tpm2_buf_append_auth(&buf, TPM2_RS_PW,
- NULL /* nonce */, 0,
- 0 /* session_attributes */,
- options->keyauth /* hmac */,
- TPM_DIGEST_SIZE);
+ tpm_buf_append_name(&buf, auth, options->keyhandle, NULL);
+ tpm_buf_append_hmac_session(&buf, auth, TPM2_SA_DECRYPT,
+ options->keyauth, TPM_DIGEST_SIZE);
/* sensitive */
tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len);
@@ -308,7 +310,11 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
goto out;
}
+ tpm_buf_fill_hmac_session(&buf, auth);
rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data");
+ if (rc)
+ goto out;
+ rc = tpm_buf_check_hmac_response(&buf, auth, rc);
if (rc)
goto out;
@@ -340,6 +346,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
else
payload->blob_len = blob_len;
+out_put:
tpm_put_ops(chip);
return rc;
}
@@ -363,6 +370,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
u32 *blob_handle)
{
struct tpm_buf buf;
+ struct tpm2_auth *auth;
unsigned int private_len;
unsigned int public_len;
unsigned int blob_len;
@@ -409,16 +417,19 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
if (blob_len > payload->blob_len)
return -E2BIG;
- rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+ rc = tpm2_start_auth_session(chip, &auth);
if (rc)
return rc;
- tpm_buf_append_u32(&buf, options->keyhandle);
- tpm2_buf_append_auth(&buf, TPM2_RS_PW,
- NULL /* nonce */, 0,
- 0 /* session_attributes */,
- options->keyauth /* hmac */,
- TPM_DIGEST_SIZE);
+ rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+ if (rc) {
+ tpm2_end_auth_session(auth);
+ return rc;
+ }
+
+ tpm_buf_append_name(&buf, auth, options->keyhandle, NULL);
+ tpm_buf_append_hmac_session(&buf, auth, 0, options->keyauth,
+ TPM_DIGEST_SIZE);
tpm_buf_append(&buf, blob, blob_len);
@@ -427,7 +438,9 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
goto out;
}
+ tpm_buf_fill_hmac_session(&buf, auth);
rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob");
+ rc = tpm_buf_check_hmac_response(&buf, auth, rc);
if (!rc)
*blob_handle = be32_to_cpup(
(__be32 *) &buf.data[TPM_HEADER_SIZE]);
@@ -461,24 +474,44 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
u32 blob_handle)
{
struct tpm_buf buf;
+ struct tpm2_auth *auth;
u16 data_len;
u8 *data;
int rc;
- rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
+ rc = tpm2_start_auth_session(chip, &auth);
if (rc)
return rc;
- tpm_buf_append_u32(&buf, blob_handle);
- tpm2_buf_append_auth(&buf,
- options->policyhandle ?
- options->policyhandle : TPM2_RS_PW,
- NULL /* nonce */, 0,
- TPM2_SA_CONTINUE_SESSION,
- options->blobauth /* hmac */,
- options->blobauth_len);
+ rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
+ if (rc) {
+ tpm2_end_auth_session(auth);
+ return rc;
+ }
+
+ tpm_buf_append_name(&buf, auth, blob_handle, NULL);
+
+ if (!options->policyhandle) {
+ tpm_buf_append_hmac_session(&buf, auth, TPM2_SA_ENCRYPT,
+ options->blobauth, TPM_DIGEST_SIZE);
+ } else {
+ /*
+ * FIXME: if we generated the policyhandle, we know the nonce
+ * and therefore could use it for session encryption, but we
+ * can't for the external policy handle case, so we treat both
+ * the same here.
+ */
+ tpm2_buf_append_auth(&buf, options->policyhandle,
+ NULL /* nonce */, 0, 0,
+ options->blobauth /* hmac */,
+ TPM_DIGEST_SIZE);
+ tpm_buf_append_hmac_session_opt(&buf, auth, TPM2_SA_ENCRYPT,
+ NULL, 0);
+ }
+ tpm_buf_fill_hmac_session(&buf, auth);
rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
+ rc = tpm_buf_check_hmac_response(&buf, auth, rc);
if (rc > 0)
rc = -EPERM;
--
2.35.3
