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F-5654 F-5719 F-5277 F-5122 F-4845 F-4955 - Harden fwTPM fixes per review

pull/518/head
aidan garske 2026-06-02 14:24:11 -07:00
parent 34930558e3
commit 5453e6ff26
3 changed files with 73 additions and 19 deletions
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82
src/fwtpm/fwtpm_command.c
View File

@ -866,8 +866,12 @@ static TPM_RC FwCmd_IncrementalSelfTest(FWTPM_CTX* ctx, TPM2_Packet* cmd,
}
if (rc == 0) {
TPM2_Packet_ParseU32(cmd, &toTestCount);
if (cmdSize < TPM2_HEADER_SIZE + 4 + (int)(toTestCount * sizeof(alg)))
/* Bound by division to avoid the count*size multiply overflowing and
* wrapping the size check (which would allow an unbounded loop). */
if (toTestCount > (UINT32)((cmdSize - (TPM2_HEADER_SIZE + 4)) /
(int)sizeof(alg))) {
rc = TPM_RC_COMMAND_SIZE;
}
}
if (rc == 0) {
for (i = 0; i < toTestCount; i++)
@ -6993,15 +6997,23 @@ static TPM_RC FwCmd_HMAC(FWTPM_CTX* ctx, TPM2_Packet* cmd,
/* Parse hashAlg */
TPM2_Packet_ParseU16(cmd, (UINT16*)&hashAlg);
/* NULL means use the key's HMAC scheme hash; a non-NULL value must
* match it (Part 3 Sec.17.4) rather than any wire-chosen hash. */
if (hashAlg == TPM_ALG_NULL) {
hashAlg = obj->pub.parameters.keyedHashDetail.scheme.details
.hmac.hashAlg;
/* If the key binds an HMAC scheme, a NULL wire hash uses it and a
* non-NULL wire hash must match it (Part 3 Sec.17.4). A key with an
* unbound (NULL) scheme lets the caller choose, defaulting to the
* key's nameAlg. */
if (obj->pub.parameters.keyedHashDetail.scheme.scheme
!= TPM_ALG_NULL) {
if (hashAlg == TPM_ALG_NULL) {
hashAlg = obj->pub.parameters.keyedHashDetail.scheme
.details.hmac.hashAlg;
}
else if (hashAlg != obj->pub.parameters.keyedHashDetail.scheme
.details.hmac.hashAlg) {
rc = TPM_RC_VALUE;
}
}
else if (hashAlg != obj->pub.parameters.keyedHashDetail.scheme
.details.hmac.hashAlg) {
rc = TPM_RC_VALUE;
else if (hashAlg == TPM_ALG_NULL) {
hashAlg = obj->pub.nameAlg;
}
ht = FwGetWcHashType(hashAlg);
@ -8962,10 +8974,21 @@ static TPM_RC FwCmd_PolicySecret(FWTPM_CTX* ctx, TPM2_Packet* cmd,
}
}
/* Bind the command to cpHashA so policy enforcement can verify it */
/* Bind the command to cpHashA so policy enforcement can verify it.
* Lock-once: if already bound, a different value must be rejected
* rather than silently replacing the earlier binding. */
if (rc == 0 && cpHashASz > 0) {
sess->cpHashA.size = cpHashASz;
XMEMCPY(sess->cpHashA.buffer, cpHashBuf, cpHashASz);
if (sess->cpHashA.size > 0) {
if (sess->cpHashA.size != cpHashASz ||
TPM2_ConstantCompare(sess->cpHashA.buffer, cpHashBuf,
cpHashASz) != 0) {
rc = TPM_RC_CPHASH;
}
}
else {
sess->cpHashA.size = cpHashASz;
XMEMCPY(sess->cpHashA.buffer, cpHashBuf, cpHashASz);
}
}
if (rc == 0) {
@ -9302,12 +9325,15 @@ static TPM_RC FwCmd_PolicyLocality(FWTPM_CTX* ctx, TPM2_Packet* cmd,
NULL, 0, 0) != 0) {
rc = TPM_RC_FAILURE;
}
/* Bind the locality constraint (intersect across calls) */
/* Bind the locality constraint (intersect across calls). A flag
* marks it present so a bitmap of 0 stays an unsatisfiable
* constraint rather than reading as "unset". */
if (rc == 0) {
if (sess->requiredLocality == 0)
if (!sess->hasRequiredLocality)
sess->requiredLocality = locality;
else
sess->requiredLocality &= locality;
sess->hasRequiredLocality = 1;
}
}
if (rc == 0) {
@ -9473,10 +9499,21 @@ static TPM_RC FwCmd_PolicySigned(FWTPM_CTX* ctx, TPM2_Packet* cmd,
}
}
/* Bind the command to cpHashA so policy enforcement can verify it */
/* Bind the command to cpHashA so policy enforcement can verify it.
* Lock-once: if already bound, a different value must be rejected
* rather than silently replacing the earlier binding. */
if (rc == 0 && cpHashASz > 0) {
sess->cpHashA.size = cpHashASz;
XMEMCPY(sess->cpHashA.buffer, cpHashBuf, cpHashASz);
if (sess->cpHashA.size > 0) {
if (sess->cpHashA.size != cpHashASz ||
TPM2_ConstantCompare(sess->cpHashA.buffer, cpHashBuf,
cpHashASz) != 0) {
rc = TPM_RC_CPHASH;
}
}
else {
sess->cpHashA.size = cpHashASz;
XMEMCPY(sess->cpHashA.buffer, cpHashBuf, cpHashASz);
}
}
if (rc == 0) {
@ -12723,6 +12760,11 @@ static TPM_RC FwCmd_MakeCredential(FWTPM_CTX* ctx, TPM2_Packet* cmd,
rc = TPM_RC_HANDLE;
}
}
/* Credential wrap/unwrap integrity is SHA-256 only; reject other
* nameAlgs rather than emit a mixed-hash (non-interoperable) blob. */
if (rc == 0 && keyObj->pub.nameAlg != TPM_ALG_SHA256) {
rc = TPM_RC_HASH;
}
/* MakeCredential has no auth area */
@ -12902,6 +12944,10 @@ static TPM_RC FwCmd_ActivateCredential(FWTPM_CTX* ctx, TPM2_Packet* cmd,
rc = TPM_RC_HANDLE;
}
}
/* Credential wrap/unwrap integrity is SHA-256 only (see MakeCredential) */
if (rc == 0 && keyObj->pub.nameAlg != TPM_ALG_SHA256) {
rc = TPM_RC_HASH;
}
/* Skip auth area */
if (rc == 0 && cmdTag == TPM_ST_SESSIONS) {
@ -15839,7 +15885,7 @@ int FWTPM_ProcessCommand(FWTPM_CTX* ctx,
return TPM_RC_SUCCESS;
}
/* Enforce any PolicyLocality constraint bound to the session */
if (pSess->requiredLocality != 0 &&
if (pSess->hasRequiredLocality &&
!((1 << ctx->activeLocality) & pSess->requiredLocality)) {
*rspSize = FwBuildErrorResponse(rspBuf,
TPM_ST_NO_SESSIONS, TPM_RC_LOCALITY);

7
tests/fwtpm_unit_tests.c
View File

@ -8115,6 +8115,13 @@ static void test_fwtpm_incremental_selftest_truncated_returns_cmd_size(void)
FWTPM_ProcessCommand(&ctx, gCmd, 10, gRsp, &rspSize, 0);
AssertIntEQ(GetRspRC(gRsp), TPM_RC_COMMAND_SIZE);
/* Overflow case: a huge count must be rejected, not wrap the size check */
BuildCmdHeader(gCmd, TPM_ST_NO_SESSIONS, 14, TPM_CC_IncrementalSelfTest);
PutU32BE(gCmd + 10, 0xFFFFFFFFu);
rspSize = 0;
FWTPM_ProcessCommand(&ctx, gCmd, 14, gRsp, &rspSize, 0);
AssertIntEQ(GetRspRC(gRsp), TPM_RC_COMMAND_SIZE);
FWTPM_Cleanup(&ctx);
printf("Test fwTPM:\tIncrementalSelfTest truncated (CMD_SIZE):\tPassed\n");
}

3
wolftpm/fwtpm/fwtpm.h
View File

@ -529,7 +529,8 @@ typedef struct FWTPM_Session {
TPM2B_DIGEST cpHashA; /* PolicyCpHash: locked once set */
TPM2B_DIGEST nameHash; /* PolicyNameHash: locked once set */
int isPPRequired; /* PolicyPhysicalPresence flag */
int requiredLocality; /* PolicyLocality bitmap (0 = unset) */
int requiredLocality; /* PolicyLocality bitmap */
int hasRequiredLocality; /* 1 once PolicyLocality has been called */
} FWTPM_Session;
/* NV index slot (user NV RAM) */