1 // This file was extracted from the TCG Published 2 // Trusted Platform Module Library 3 // Part 3: Commands 4 // Family "2.0" 5 // Level 00 Revision 01.16 6 // October 30, 2014 7 8 #include "InternalRoutines.h" 9 // 10 // This function is called to process a _TPM_Hash_Start() indication. 11 // 12 void 13 _TPM_Hash_Start( 14 void 15 ) 16 { 17 TPM_RC result; 18 TPMI_DH_OBJECT handle; 19 20 // If a DRTM sequence object exists, free it up 21 if(g_DRTMHandle != TPM_RH_UNASSIGNED) 22 { 23 ObjectFlush(g_DRTMHandle); 24 g_DRTMHandle = TPM_RH_UNASSIGNED; 25 } 26 27 // Create an event sequence object and store the handle in global 28 // g_DRTMHandle. A TPM_RC_OBJECT_MEMORY error may be returned at this point 29 // The null value for the 'auth' parameter will cause the sequence structure to 30 // be allocated without being set as present. This keeps the sequence from 31 // being left behind if the sequence is terminated early. 32 result = ObjectCreateEventSequence(NULL, &g_DRTMHandle); 33 34 // If a free slot was not available, then free up a slot. 35 if(result != TPM_RC_SUCCESS) 36 { 37 // An implementation does not need to have a fixed relationship between 38 // slot numbers and handle numbers. To handle the general case, scan for 39 // a handle that is assigned and free it for the DRTM sequence. 40 // In the reference implementation, the relationship between handles and 41 // slots is fixed. So, if the call to ObjectCreateEvenSequence() 42 // failed indicating that all slots are occupied, then the first handle we 43 // are going to check (TRANSIENT_FIRST) will be occupied. It will be freed 44 // so that it can be assigned for use as the DRTM sequence object. 45 for(handle = TRANSIENT_FIRST; handle < TRANSIENT_LAST; handle++) 46 { 47 // try to flush the first object 48 if(ObjectIsPresent(handle)) 49 break; 50 } 51 // If the first call to find a slot fails but none of the slots is occupied 52 // then there's a big problem 53 pAssert(handle < TRANSIENT_LAST); 54 55 // Free the slot 56 ObjectFlush(handle); 57 58 // Try to create an event sequence object again. This time, we must 59 // succeed. 60 result = ObjectCreateEventSequence(NULL, &g_DRTMHandle); 61 pAssert(result == TPM_RC_SUCCESS); 62 } 63 64 return; 65 } 66
