[Trousers-scm] [GIT] Trousers master branch updated. TROUSERS_0_3_12-7-g88d6fbe

[Richard Maciel]

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- Log -----------------------------------------------------------------
http://trousers.git.sourceforge.net/git/gitweb.cgi?p=trousers/trousers;a=commitdiff;h=88d6fbe11807519a86c09ebea94878fcbff31e2f

commit 88d6fbe11807519a86c09ebea94878fcbff31e2f
Author: Richard Maciel <***@linux.vnet.ibm.com>
Date: Tue Feb 25 10:55:23 2014 -0300

Don't allow TrouSerS to wrap asymmetric key > 2048 bits

Previously the tspi layer accepted external asymmetric keys of any
size to be wrapped by the TPM, however it allocated buffers capable
of only holding private keys with at most 2048 bits.

A test was added to prevent this behavior, since the TPM 1.1b and
1.2 limits that size, according to the TPM_STORE_ASYMKEY structure.

Also, comments and defines were added to make the life of future
maintainers easier when debugging that function.

Signed-off-by: Richard Maciel <***@linux.vnet.ibm.com>

diff --git a/src/tspi/tspi_key.c b/src/tspi/tspi_key.c
index bfead42..aa4df50 100644
--- a/src/tspi/tspi_key.c
+++ b/src/tspi/tspi_key.c
@@ -23,6 +23,11 @@
#include "obj.h"
#include "authsess.h"

+#define TPM_STORE_ASYMKEY_LEN 214 /* Entire TPM_STORE_ASYMKEY length */
+#define USAGE_MIG_DIGEST_FLD_LEN 20 /* Usage, Migration and Digest lengths for
+ TPM_STORE_ASYMKEY */
+#define TPM_STORE_PRIVKEY_LEN 151 /* Extracted directly from TPM_STORE_ASYMKEY
+ field */

TSS_RESULT
Tspi_Key_UnloadKey(TSS_HKEY hKey) /* in */
@@ -343,9 +348,11 @@ Tspi_Key_WrapKey(TSS_HKEY hKey, /* in */
TSS_RESULT result;
BYTE *keyPrivBlob = NULL, *wrappingPubKey = NULL, *keyBlob = NULL;
UINT32 keyPrivBlobLen, wrappingPubKeyLen, keyBlobLen;
- BYTE newPrivKey[214]; /* its not magic, see TPM 1.1b spec p.71 */
+ BYTE newPrivKey[TPM_STORE_ASYMKEY_LEN]; /* This reflects the size of the
+ TPM_STORE_ASYMKEY structure
+ in both TPM 1.1b and 1.2 */
BYTE encPrivKey[256];
- UINT32 newPrivKeyLen = 214, encPrivKeyLen = 256;
+ UINT32 newPrivKeyLen = TPM_STORE_ASYMKEY_LEN, encPrivKeyLen = 256;
UINT64 offset;
TSS_KEY keyContainer;
TCPA_DIGEST digest;
@@ -363,6 +370,10 @@ Tspi_Key_WrapKey(TSS_HKEY hKey, /* in */
/* get the key to be wrapped's private key */
if ((result = obj_rsakey_get_priv_blob(hKey, &keyPrivBlobLen, &keyPrivBlob)))
goto done;
+ /* verify if its under the maximum size, according to the
+ * TPM_STORE_ASYMKEY specification */
+ if (keyPrivBlobLen > TPM_STORE_PRIVKEY_LEN)
+ return TSPERR(TSS_E_ENC_INVALID_LENGTH);

/* get the key to be wrapped's blob */
if ((result = obj_rsakey_get_blob(hKey, &keyBlobLen, &keyBlob)))
@@ -400,12 +411,16 @@ Tspi_Key_WrapKey(TSS_HKEY hKey, /* in */

free_key_refs(&keyContainer);

- /* create the plaintext private key blob */
+ /* create the plaintext private key blob. This is the point where the
+ * TPM structure TPM_STORE_ASYMKEY is crafted in the buffer */
offset = 0;
Trspi_LoadBlob_BYTE(&offset, TCPA_PT_ASYM, newPrivKey);
- Trspi_LoadBlob(&offset, 20, newPrivKey, usage.authdata);
- Trspi_LoadBlob(&offset, 20, newPrivKey, migration.authdata);
- Trspi_LoadBlob(&offset, 20, newPrivKey, digest.digest);
+ Trspi_LoadBlob(&offset, USAGE_MIG_DIGEST_FLD_LEN,
+ newPrivKey, usage.authdata);
+ Trspi_LoadBlob(&offset, USAGE_MIG_DIGEST_FLD_LEN,
+ newPrivKey, migration.authdata);
+ Trspi_LoadBlob(&offset, USAGE_MIG_DIGEST_FLD_LEN,
+ newPrivKey, digest.digest);
Trspi_LoadBlob_UINT32(&offset, keyPrivBlobLen, newPrivKey);
Trspi_LoadBlob(&offset, keyPrivBlobLen, newPrivKey, keyPrivBlob);
newPrivKeyLen = offset;

-----------------------------------------------------------------------

Summary of changes:
src/tspi/tspi_key.c | 27 +++++++++++++++++++++------
1 files changed, 21 insertions(+), 6 deletions(-)


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