/********************************************************************************/ /* */ /* Manage the session context counter */ /* Written by Ken Goldman */ /* IBM Thomas J. Watson Research Center */ /* $Id: Session.c 1594 2020-03-26 22:15:48Z kgoldman $ */ /* */ /* Licenses and Notices */ /* */ /* 1. Copyright Licenses: */ /* */ /* - Trusted Computing Group (TCG) grants to the user of the source code in */ /* this specification (the "Source Code") a worldwide, irrevocable, */ /* nonexclusive, royalty free, copyright license to reproduce, create */ /* derivative works, distribute, display and perform the Source Code and */ /* derivative works thereof, and to grant others the rights granted herein. */ /* */ /* - The TCG grants to the user of the other parts of the specification */ /* (other than the Source Code) the rights to reproduce, distribute, */ /* display, and perform the specification solely for the purpose of */ /* developing products based on such documents. */ /* */ /* 2. 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At startup, all the in-memory session slots // are cleared and marked as not occupied for(i = 0; i < MAX_LOADED_SESSIONS; i++) s_sessions[i].occupied = FALSE; // session slot is not occupied // The free session slots the number of maximum allowed loaded sessions s_freeSessionSlots = MAX_LOADED_SESSIONS; // Initialize context ID data. On a ST_SAVE or hibernate sequence, it will // scan the saved array of session context counts, and clear any entry that // references a session that was in memory during the state save since that // memory was not preserved over the ST_SAVE. if(type == SU_RESUME || type == SU_RESTART) { // On ST_SAVE we preserve the contexts that were saved but not the ones // in memory for(i = 0; i < MAX_ACTIVE_SESSIONS; i++) { // If the array value is unused or references a loaded session then // that loaded session context is lost and the array entry is // reclaimed. if(gr.contextArray[i] <= MAX_LOADED_SESSIONS) gr.contextArray[i] = 0; } // Find the oldest session in context ID data and set it in // s_oldestSavedSession ContextIdSetOldest(); } else { // For STARTUP_CLEAR, clear out the contextArray for(i = 0; i < MAX_ACTIVE_SESSIONS; i++) gr.contextArray[i] = 0; // reset the context counter gr.contextCounter = MAX_LOADED_SESSIONS + 1; // Initialize oldest saved session s_oldestSavedSession = MAX_ACTIVE_SESSIONS + 1; } return TRUE; } /* 8.9.5 Access Functions */ /* 8.9.5.1 SessionIsLoaded() */ /* This function test a session handle references a loaded session. The handle must have previously been checked to make sure that it is a valid handle for an authorization session. */ /* NOTE: A PWAP authorization does not have a session. */ /* Return Values Meaning */ /* TRUE if session is loaded */ /* FALSE if it is not loaded */ BOOL SessionIsLoaded( TPM_HANDLE handle // IN: session handle ) { pAssert(HandleGetType(handle) == TPM_HT_POLICY_SESSION || HandleGetType(handle) == TPM_HT_HMAC_SESSION); handle = handle & HR_HANDLE_MASK; // if out of range of possible active session, or not assigned to a loaded // session return false if(handle >= MAX_ACTIVE_SESSIONS || gr.contextArray[handle] == 0 || gr.contextArray[handle] > MAX_LOADED_SESSIONS) return FALSE; return TRUE; } /* 8.9.5.2 SessionIsSaved() */ /* This function test a session handle references a saved session. The handle must have previously been checked to make sure that it is a valid handle for an authorization session. */ /* NOTE: A password authorization does not have a session. */ /* This function requires that the handle be a valid session handle. */ /* Return Values Meaning */ /* TRUE if session is saved */ /* FALSE if it is not saved */ BOOL SessionIsSaved( TPM_HANDLE handle // IN: session handle ) { pAssert(HandleGetType(handle) == TPM_HT_POLICY_SESSION || HandleGetType(handle) == TPM_HT_HMAC_SESSION); handle = handle & HR_HANDLE_MASK; // if out of range of possible active session, or not assigned, or // assigned to a loaded session, return false if(handle >= MAX_ACTIVE_SESSIONS || gr.contextArray[handle] == 0 || gr.contextArray[handle] <= MAX_LOADED_SESSIONS ) return FALSE; return TRUE; } /* 8.9.5.3 SequenceNumberForSavedContextIsValid() */ BOOL SequenceNumberForSavedContextIsValid( TPMS_CONTEXT *context // IN: pointer to a context // structure to be validated ) { #define MAX_CONTEXT_GAP ((UINT64)((CONTEXT_SLOT) ~0) + 1) TPM_HANDLE handle = context->savedHandle & HR_HANDLE_MASK; if(// Handle must be with the range of active sessions handle >= MAX_ACTIVE_SESSIONS // the array entry must be for a saved context || gr.contextArray[handle] <= MAX_LOADED_SESSIONS // the array entry must agree with the sequence number || gr.contextArray[handle] != (CONTEXT_SLOT)context->sequence // the provided sequence number has to be less than the current counter || context->sequence > gr.contextCounter // but not so much that it could not be a valid sequence number || gr.contextCounter - context->sequence > MAX_CONTEXT_GAP) return FALSE; return TRUE; } /* 8.9.5.4 SessionPCRValueIsCurrent() */ /* This function is used to check if PCR values have been updated since the last time they were checked in a policy session. */ /* This function requires the session is loaded. */ /* Return Values Meaning */ /* TRUE if PCR value is current */ /* FALSE if PCR value is not current */ BOOL SessionPCRValueIsCurrent( SESSION *session // IN: session structure ) { if(session->pcrCounter != 0 && session->pcrCounter != gr.pcrCounter ) return FALSE; else return TRUE; } /* 8.9.5.5 SessionGet() */ /* This function returns a pointer to the session object associated with a session handle. */ /* The function requires that the session is loaded. */ SESSION * SessionGet( TPM_HANDLE handle // IN: session handle ) { size_t slotIndex; CONTEXT_SLOT sessionIndex; pAssert(HandleGetType(handle) == TPM_HT_POLICY_SESSION || HandleGetType(handle) == TPM_HT_HMAC_SESSION ); slotIndex = handle & HR_HANDLE_MASK; pAssert(slotIndex < MAX_ACTIVE_SESSIONS); // get the contents of the session array. Because session is loaded, we // should always get a valid sessionIndex sessionIndex = gr.contextArray[slotIndex] - 1; pAssert(sessionIndex < MAX_LOADED_SESSIONS); return &s_sessions[sessionIndex].session; } /* 8.9.6 Utility Functions */ /* 8.9.6.1 ContextIdSessionCreate() */ /* This function is called when a session is created. It will check to see if the current gap would prevent a context from being saved. If so it will return TPM_RC_CONTEXT_GAP. Otherwise, it will try to find an open slot in contextArray, set contextArray to the slot. This routine requires that the caller has determined the session array index for the session. */ /* TPM_RC_CONTEXT_GAP can't assign a new contextID until the oldest saved session context is recycled */ /* TPM_RC_SESSION_HANDLE there is no slot available in the context array for tracking of this session context */ static TPM_RC ContextIdSessionCreate( TPM_HANDLE *handle, /* OUT: receives the assigned handle. This will be an index that must be adjusted by the caller according to the type of the session created */ UINT32 sessionIndex /* IN: The session context array entry that will be occupied by the created session */ ) { pAssert(sessionIndex < MAX_LOADED_SESSIONS); // check to see if creating the context is safe // Is this going to be an assignment for the last session context // array entry? If so, then there will be no room to recycle the // oldest context if needed. If the gap is not at maximum, then // it will be possible to save a context if it becomes necessary. if(s_oldestSavedSession < MAX_ACTIVE_SESSIONS && s_freeSessionSlots == 1) { // See if the gap is at maximum // The current value of the contextCounter will be assigned to the next // saved context. If the value to be assigned would make the same as an // existing context, then we can't use it because of the ambiguity it would // create. if((CONTEXT_SLOT)gr.contextCounter == gr.contextArray[s_oldestSavedSession]) return TPM_RC_CONTEXT_GAP; } // Find an unoccupied entry in the contextArray for(*handle = 0; *handle < MAX_ACTIVE_SESSIONS; (*handle)++) { if(gr.contextArray[*handle] == 0) { // indicate that the session associated with this handle // references a loaded session gr.contextArray[*handle] = (CONTEXT_SLOT)(sessionIndex + 1); return TPM_RC_SUCCESS; } } return TPM_RC_SESSION_HANDLES; } /* 8.9.6.2 SessionCreate() */ /* This function does the detailed work for starting an authorization session. This is done in a support routine rather than in the action code because the session management may differ in implementations. This implementation uses a fixed memory allocation to hold sessions and a fixed allocation to hold the contextID for the saved contexts. */ /* Error Returns Meaning */ /* TPM_RC_CONTEXT_GAP need to recycle sessions */ /* TPM_RC_SESSION_HANDLE active session space is full */ /* TPM_RC_SESSION_MEMORY loaded session space is full */ TPM_RC SessionCreate( TPM_SE sessionType, // IN: the session type TPMI_ALG_HASH authHash, // IN: the hash algorithm TPM2B_NONCE *nonceCaller, // IN: initial nonceCaller TPMT_SYM_DEF *symmetric, // IN: the symmetric algorithm TPMI_DH_ENTITY bind, // IN: the bind object TPM2B_DATA *seed, // IN: seed data TPM_HANDLE *sessionHandle, // OUT: the session handle TPM2B_NONCE *nonceTpm // OUT: the session nonce ) { TPM_RC result = TPM_RC_SUCCESS; CONTEXT_SLOT slotIndex; SESSION *session = NULL; pAssert(sessionType == TPM_SE_HMAC || sessionType == TPM_SE_POLICY || sessionType == TPM_SE_TRIAL); // If there are no open spots in the session array, then no point in searching if(s_freeSessionSlots == 0) return TPM_RC_SESSION_MEMORY; // Find a space for loading a session for(slotIndex = 0; slotIndex < MAX_LOADED_SESSIONS; slotIndex++) { // Is this available? if(s_sessions[slotIndex].occupied == FALSE) { session = &s_sessions[slotIndex].session; break; } } // if no spot found, then this is an internal error if(slotIndex >= MAX_LOADED_SESSIONS) FAIL(FATAL_ERROR_INTERNAL); // Call context ID function to get a handle. TPM_RC_SESSION_HANDLE may be // returned from ContextIdHandelAssign() result = ContextIdSessionCreate(sessionHandle, slotIndex); if(result != TPM_RC_SUCCESS) return result; //*** Only return from this point on is TPM_RC_SUCCESS // Can now indicate that the session array entry is occupied. s_freeSessionSlots--; s_sessions[slotIndex].occupied = TRUE; // Initialize the session data MemorySet(session, 0, sizeof(SESSION)); // Initialize internal session data session->authHashAlg = authHash; // Initialize session type if(sessionType == TPM_SE_HMAC) { *sessionHandle += HMAC_SESSION_FIRST; } else { *sessionHandle += POLICY_SESSION_FIRST; // For TPM_SE_POLICY or TPM_SE_TRIAL session->attributes.isPolicy = SET; if(sessionType == TPM_SE_TRIAL) session->attributes.isTrialPolicy = SET; SessionSetStartTime(session); // Initialize policyDigest. policyDigest is initialized with a string of 0 // of session algorithm digest size. Since the session is already clear. // Just need to set the size session->u2.policyDigest.t.size = CryptHashGetDigestSize(session->authHashAlg); } // Create initial session nonce session->nonceTPM.t.size = nonceCaller->t.size; CryptRandomGenerate(session->nonceTPM.t.size, session->nonceTPM.t.buffer); MemoryCopy2B(&nonceTpm->b, &session->nonceTPM.b, sizeof(nonceTpm->t.buffer)); // Set up session parameter encryption algorithm session->symmetric = *symmetric; // If there is a bind object or a session secret, then need to compute // a sessionKey. if(bind != TPM_RH_NULL || seed->t.size != 0) { // sessionKey = KDFa(hash, (authValue || seed), "ATH", nonceTPM, // nonceCaller, bits) // The HMAC key for generating the sessionSecret can be the concatenation // of an authorization value and a seed value TPM2B_TYPE(KEY, (sizeof(TPMT_HA) + sizeof(seed->t.buffer))); TPM2B_KEY key; // Get hash size, which is also the length of sessionKey session->sessionKey.t.size = CryptHashGetDigestSize(session->authHashAlg); // Get authValue of associated entity EntityGetAuthValue(bind, (TPM2B_AUTH *)&key); pAssert(key.t.size + seed->t.size <= sizeof(key.t.buffer)); // Concatenate authValue and seed MemoryConcat2B(&key.b, &seed->b, sizeof(key.t.buffer)); // Compute the session key CryptKDFa(session->authHashAlg, &key.b, SESSION_KEY, &session->nonceTPM.b, &nonceCaller->b, session->sessionKey.t.size * 8, session->sessionKey.t.buffer, NULL, FALSE); } // Copy the name of the entity that the HMAC session is bound to // Policy session is not bound to an entity if(bind != TPM_RH_NULL && sessionType == TPM_SE_HMAC) { session->attributes.isBound = SET; SessionComputeBoundEntity(bind, &session->u1.boundEntity); } // If there is a bind object and it is subject to DA, then use of this session // is subject to DA regardless of how it is used. session->attributes.isDaBound = (bind != TPM_RH_NULL) && (IsDAExempted(bind) == FALSE); // If the session is bound, then check to see if it is bound to lockoutAuth session->attributes.isLockoutBound = (session->attributes.isDaBound == SET) && (bind == TPM_RH_LOCKOUT); return TPM_RC_SUCCESS; } /* 8.9.6.3 SessionContextSave() */ /* This function is called when a session context is to be saved. The contextID of the saved session is returned. If no contextID can be assigned, then the routine returns TPM_RC_CONTEXT_GAP. If the function completes normally, the session slot will be freed. */ /* This function requires that handle references a loaded session. Otherwise, it should not be called at the first place. */ /* Error Returns Meaning */ /* TPM_RC_CONTEXT_GAP a contextID could not be assigned. */ /* TPM_RC_TOO_MANY_CONTEXTS the counter maxed out */ TPM_RC SessionContextSave( TPM_HANDLE handle, // IN: session handle CONTEXT_COUNTER *contextID // OUT: assigned contextID ) { UINT32 contextIndex; CONTEXT_SLOT slotIndex; pAssert(SessionIsLoaded(handle)); // check to see if the gap is already maxed out // Need to have a saved session if(s_oldestSavedSession < MAX_ACTIVE_SESSIONS // if the oldest saved session has the same value as the low bits // of the contextCounter, then the GAP is maxed out. && gr.contextArray[s_oldestSavedSession] == (CONTEXT_SLOT)gr.contextCounter) return TPM_RC_CONTEXT_GAP; // if the caller wants the context counter, set it if(contextID != NULL) *contextID = gr.contextCounter; contextIndex = handle & HR_HANDLE_MASK; pAssert(contextIndex < MAX_ACTIVE_SESSIONS); // Extract the session slot number referenced by the contextArray // because we are going to overwrite this with the low order // contextID value. slotIndex = gr.contextArray[contextIndex] - 1; // Set the contextID for the contextArray gr.contextArray[contextIndex] = (CONTEXT_SLOT)gr.contextCounter; // Increment the counter gr.contextCounter++; // In the unlikely event that the 64-bit context counter rolls over... if(gr.contextCounter == 0) { // back it up gr.contextCounter--; // return an error return TPM_RC_TOO_MANY_CONTEXTS; } // if the low-order bits wrapped, need to advance the value to skip over // the values used to indicate that a session is loaded if(((CONTEXT_SLOT)gr.contextCounter) == 0) gr.contextCounter += MAX_LOADED_SESSIONS + 1; // If no other sessions are saved, this is now the oldest. if(s_oldestSavedSession >= MAX_ACTIVE_SESSIONS) s_oldestSavedSession = contextIndex; // Mark the session slot as unoccupied s_sessions[slotIndex].occupied = FALSE; // and indicate that there is an additional open slot s_freeSessionSlots++; return TPM_RC_SUCCESS; } /* 8.9.6.4 SessionContextLoad() */ /* This function is used to load a session from saved context. The session handle must be for a saved context. */ /* If the gap is at a maximum, then the only session that can be loaded is the oldest session, otherwise TPM_RC_CONTEXT_GAP is returned. */ /* This function requires that handle references a valid saved session. */ /* Error Returns Meaning */ /* TPM_RC_SESSION_MEMORY no free session slots */ /* TPM_RC_CONTEXT_GAP the gap count is maximum and this is not the oldest saved context */ TPM_RC SessionContextLoad( SESSION_BUF *session, // IN: session structure from saved context TPM_HANDLE *handle // IN/OUT: session handle ) { UINT32 contextIndex; CONTEXT_SLOT slotIndex; pAssert(HandleGetType(*handle) == TPM_HT_POLICY_SESSION || HandleGetType(*handle) == TPM_HT_HMAC_SESSION); // Don't bother looking if no openings if(s_freeSessionSlots == 0) return TPM_RC_SESSION_MEMORY; // Find a free session slot to load the session for(slotIndex = 0; slotIndex < MAX_LOADED_SESSIONS; slotIndex++) if(s_sessions[slotIndex].occupied == FALSE) break; // if no spot found, then this is an internal error pAssert(slotIndex < MAX_LOADED_SESSIONS); contextIndex = *handle & HR_HANDLE_MASK; // extract the index // If there is only one slot left, and the gap is at maximum, the only session // context that we can safely load is the oldest one. if(s_oldestSavedSession < MAX_ACTIVE_SESSIONS && s_freeSessionSlots == 1 && (CONTEXT_SLOT)gr.contextCounter == gr.contextArray[s_oldestSavedSession] && contextIndex != s_oldestSavedSession) return TPM_RC_CONTEXT_GAP; pAssert(contextIndex < MAX_ACTIVE_SESSIONS); // set the contextArray value to point to the session slot where // the context is loaded gr.contextArray[contextIndex] = slotIndex + 1; // if this was the oldest context, find the new oldest if(contextIndex == s_oldestSavedSession) ContextIdSetOldest(); // Copy session data to session slot MemoryCopy(&s_sessions[slotIndex].session, session, sizeof(SESSION)); // Set session slot as occupied s_sessions[slotIndex].occupied = TRUE; // Reduce the number of open spots s_freeSessionSlots--; return TPM_RC_SUCCESS; } /* 8.9.6.5 SessionFlush() */ /* This function is used to flush a session referenced by its handle. If the session associated with handle is loaded, the session array entry is marked as available. */ /* This function requires that handle be a valid active session. */ void SessionFlush( TPM_HANDLE handle // IN: loaded or saved session handle ) { CONTEXT_SLOT slotIndex; UINT32 contextIndex; // Index into contextArray pAssert((HandleGetType(handle) == TPM_HT_POLICY_SESSION || HandleGetType(handle) == TPM_HT_HMAC_SESSION ) && (SessionIsLoaded(handle) || SessionIsSaved(handle)) ); // Flush context ID of this session // Convert handle to an index into the contextArray contextIndex = handle & HR_HANDLE_MASK; pAssert(contextIndex < sizeof(gr.contextArray) / sizeof(gr.contextArray[0])); // Get the current contents of the array slotIndex = gr.contextArray[contextIndex]; // Mark context array entry as available gr.contextArray[contextIndex] = 0; // Is this a saved session being flushed if(slotIndex > MAX_LOADED_SESSIONS) { // Flushing the oldest session? if(contextIndex == s_oldestSavedSession) // If so, find a new value for oldest. ContextIdSetOldest(); } else { // Adjust slot index to point to session array index slotIndex -= 1; // Free session array index s_sessions[slotIndex].occupied = FALSE; s_freeSessionSlots++; } return; } /* 8.9.6.6 SessionComputeBoundEntity() */ /* This function computes the binding value for a session. The binding value for a reserved handle is the handle itself. For all the other entities, the authValue at the time of binding is included to prevent squatting. For those values, the Name and the authValue are concatenated into the bind buffer. If they will not both fit, the will be overlapped by XORing() bytes. If XOR is required, the bind value will be full. */ void SessionComputeBoundEntity( TPMI_DH_ENTITY entityHandle, // IN: handle of entity TPM2B_NAME *bind // OUT: binding value ) { TPM2B_AUTH auth; BYTE *pAuth = auth.t.buffer; UINT16 i; // Get name EntityGetName(entityHandle, bind); // // The bound value of a reserved handle is the handle itself // if(bind->t.size == sizeof(TPM_HANDLE)) return; // For all the other entities, concatenate the authorization value to the name. // Get a local copy of the authorization value because some overlapping // may be necessary. EntityGetAuthValue(entityHandle, &auth); // Make sure that the extra space is zeroed MemorySet(&bind->t.name[bind->t.size], 0, sizeof(bind->t.name) - bind->t.size); // XOR the authValue at the end of the name for(i = sizeof(bind->t.name) - auth.t.size; i < sizeof(bind->t.name); i++) bind->t.name[i] ^= *pAuth++; // Set the bind value to the maximum size bind->t.size = sizeof(bind->t.name); return; } /* 8.9.6.7 SessionSetStartTime() */ /* This function is used to initialize the session timing */ void SessionSetStartTime( SESSION *session // IN: the session to update ) { session->startTime = g_time; session->epoch = g_timeEpoch; session->timeout = 0; } /* 8.9.6.8 SessionResetPolicyData() */ /* This function is used to reset the policy data without changing the nonce or the start time of the session. */ void SessionResetPolicyData( SESSION *session // IN: the session to reset ) { SESSION_ATTRIBUTES oldAttributes; pAssert(session != NULL); // Will need later oldAttributes = session->attributes; // No command session->commandCode = 0; // No locality selected MemorySet(&session->commandLocality, 0, sizeof(session->commandLocality)); // The cpHash size to zero session->u1.cpHash.b.size = 0; // No timeout session->timeout = 0; // Reset the pcrCounter session->pcrCounter = 0; // Reset the policy hash MemorySet(&session->u2.policyDigest.t.buffer, 0, session->u2.policyDigest.t.size); // Reset the session attributes MemorySet(&session->attributes, 0, sizeof(SESSION_ATTRIBUTES)); // Restore the policy attributes session->attributes.isPolicy = SET; session->attributes.isTrialPolicy = oldAttributes.isTrialPolicy; // Restore the bind attributes session->attributes.isDaBound = oldAttributes.isDaBound; session->attributes.isLockoutBound = oldAttributes.isLockoutBound; } /* 8.9.6.9 SessionCapGetLoaded() */ /* This function returns a list of handles of loaded session, started from input handle */ /* Handle must be in valid loaded session handle range, but does not have to point to a loaded session. */ /* Return Values Meaning */ /* YES if there are more handles available */ /* NO all the available handles has been returned */ TPMI_YES_NO SessionCapGetLoaded( TPMI_SH_POLICY handle, // IN: start handle UINT32 count, // IN: count of returned handles TPML_HANDLE *handleList // OUT: list of handle ) { TPMI_YES_NO more = NO; UINT32 i; pAssert(HandleGetType(handle) == TPM_HT_LOADED_SESSION); // Initialize output handle list handleList->count = 0; // The maximum count of handles we may return is MAX_CAP_HANDLES if(count > MAX_CAP_HANDLES) count = MAX_CAP_HANDLES; // Iterate session context ID slots to get loaded session handles for(i = handle & HR_HANDLE_MASK; i < MAX_ACTIVE_SESSIONS; i++) { // If session is active if(gr.contextArray[i] != 0) { // If session is loaded if(gr.contextArray[i] <= MAX_LOADED_SESSIONS) { if(handleList->count < count) { SESSION *session; // If we have not filled up the return list, add this // session handle to it // assume that this is going to be an HMAC session handle = i + HMAC_SESSION_FIRST; session = SessionGet(handle); if(session->attributes.isPolicy) handle = i + POLICY_SESSION_FIRST; handleList->handle[handleList->count] = handle; handleList->count++; } else { // If the return list is full but we still have loaded object // available, report this and stop iterating more = YES; break; } } } } return more; } /* 8.9.6.10 SessionCapGetSaved() */ /* This function returns a list of handles for saved session, starting at handle. */ /* Handle must be in a valid handle range, but does not have to point to a saved session */ /* Return Values Meaning */ /* YES if there are more handles available */ /* NO all the available handles has been returned */ TPMI_YES_NO SessionCapGetSaved( TPMI_SH_HMAC handle, // IN: start handle UINT32 count, // IN: count of returned handles TPML_HANDLE *handleList // OUT: list of handle ) { TPMI_YES_NO more = NO; UINT32 i; #ifdef TPM_HT_SAVED_SESSION pAssert(HandleGetType(handle) == TPM_HT_SAVED_SESSION); #else pAssert(HandleGetType(handle) == TPM_HT_ACTIVE_SESSION); #endif // Initialize output handle list handleList->count = 0; // The maximum count of handles we may return is MAX_CAP_HANDLES if(count > MAX_CAP_HANDLES) count = MAX_CAP_HANDLES; // Iterate session context ID slots to get loaded session handles for(i = handle & HR_HANDLE_MASK; i < MAX_ACTIVE_SESSIONS; i++) { // If session is active if(gr.contextArray[i] != 0) { // If session is saved if(gr.contextArray[i] > MAX_LOADED_SESSIONS) { if(handleList->count < count) { // If we have not filled up the return list, add this // session handle to it handleList->handle[handleList->count] = i + HMAC_SESSION_FIRST; handleList->count++; } else { // If the return list is full but we still have loaded object // available, report this and stop iterating more = YES; break; } } } } return more; } /* 8.9.6.11 SessionCapGetLoadedNumber() */ /* This function return the number of authorization sessions currently loaded into TPM RAM. */ UINT32 SessionCapGetLoadedNumber( void ) { return MAX_LOADED_SESSIONS - s_freeSessionSlots; } /* 8.9.6.12 SessionCapGetLoadedAvail() */ /* This function returns the number of additional authorization sessions, of any type, that could be loaded into TPM RAM. */ /* NOTE: In other implementations, this number may just be an estimate. The only requirement for the estimate is, if it is one or more, then at least one session must be loadable. */ UINT32 SessionCapGetLoadedAvail( void ) { return s_freeSessionSlots; } /* 8.9.6.13 SessionCapGetActiveNumber() */ /* This function returns the number of active authorization sessions currently being tracked by the TPM. */ UINT32 SessionCapGetActiveNumber( void ) { UINT32 i; UINT32 num = 0; // Iterate the context array to find the number of non-zero slots for(i = 0; i < MAX_ACTIVE_SESSIONS; i++) { if(gr.contextArray[i] != 0) num++; } return num; } /* 8.9.6.14 SessionCapGetActiveAvail() */ /* This function returns the number of additional authorization sessions, of any type, that could be created. This not the number of slots for sessions, but the number of additional sessions that the TPM is capable of tracking. */ UINT32 SessionCapGetActiveAvail( void ) { UINT32 i; UINT32 num = 0; // Iterate the context array to find the number of zero slots for(i = 0; i < MAX_ACTIVE_SESSIONS; i++) { if(gr.contextArray[i] == 0) num++; } return num; }