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 #include "StartAuthSession_fp.h"
10 //
11 //
12 // Error Returns Meaning
13 //
14 // TPM_RC_ATTRIBUTES tpmKey does not reference a decrypt key
15 // TPM_RC_CONTEXT_GAP the difference between the most recently created active context and
16 // the oldest active context is at the limits of the TPM
17 // TPM_RC_HANDLE input decrypt key handle only has public portion loaded
18 // TPM_RC_MODE symmetric specifies a block cipher but the mode is not
19 // TPM_ALG_CFB.
20 // TPM_RC_SESSION_HANDLES no session handle is available
21 // TPM_RC_SESSION_MEMORY no more slots for loading a session
22 // TPM_RC_SIZE nonce less than 16 octets or greater than the size of the digest
23 // produced by authHash
24 // TPM_RC_VALUE secret size does not match decrypt key type; or the recovered secret
25 // is larger than the digest size of the nameAlg of tpmKey; or, for an
26 // RSA decrypt key, if encryptedSecret is greater than the public
27 // exponent of tpmKey.
28 //
29 TPM_RC
TPM2_StartAuthSession(StartAuthSession_In * in,StartAuthSession_Out * out)30 TPM2_StartAuthSession(
31 StartAuthSession_In *in, // IN: input parameter buffer
32 StartAuthSession_Out *out // OUT: output parameter buffer
33 )
34 {
35 TPM_RC result = TPM_RC_SUCCESS;
36 OBJECT *tpmKey; // TPM key for decrypt salt
37 SESSION *session; // session internal data
38 TPM2B_DATA salt;
39
40 // Input Validation
41
42 // Check input nonce size. IT should be at least 16 bytes but not larger
43 // than the digest size of session hash.
44 if( in->nonceCaller.t.size < 16
45 || in->nonceCaller.t.size > CryptGetHashDigestSize(in->authHash))
46 return TPM_RC_SIZE + RC_StartAuthSession_nonceCaller;
47
48 // If an decrypt key is passed in, check its validation
49 if(in->tpmKey != TPM_RH_NULL)
50 {
51 // secret size cannot be 0
52 if(in->encryptedSalt.t.size == 0)
53 return TPM_RC_VALUE + RC_StartAuthSession_encryptedSalt;
54
55 // Get pointer to loaded decrypt key
56 tpmKey = ObjectGet(in->tpmKey);
57
58 // Decrypting salt requires accessing the private portion of a key.
59 // Therefore, tmpKey can not be a key with only public portion loaded
60 if(tpmKey->attributes.publicOnly)
61 return TPM_RC_HANDLE + RC_StartAuthSession_tpmKey;
62
63 // HMAC session input handle check.
64 // tpmKey should be a decryption key
65 if(tpmKey->publicArea.objectAttributes.decrypt != SET)
66 return TPM_RC_ATTRIBUTES + RC_StartAuthSession_tpmKey;
67
68 // Secret Decryption. A TPM_RC_VALUE, TPM_RC_KEY or Unmarshal errors
69 // may be returned at this point
70 result = CryptSecretDecrypt(in->tpmKey, &in->nonceCaller, "SECRET",
71 &in->encryptedSalt, &salt);
72 if(result != TPM_RC_SUCCESS)
73 return TPM_RC_VALUE + RC_StartAuthSession_encryptedSalt;
74
75 }
76 else
77 {
78 // secret size must be 0
79 if(in->encryptedSalt.t.size != 0)
80 return TPM_RC_VALUE + RC_StartAuthSession_encryptedSalt;
81 salt.t.size = 0;
82 }
83 // If the bind handle references a transient object, make sure that the
84 // sensitive area is loaded so that the authValue can be accessed.
85 if( HandleGetType(in->bind) == TPM_HT_TRANSIENT
86 && ObjectGet(in->bind)->attributes.publicOnly == SET)
87 return TPM_RC_HANDLE + RC_StartAuthSession_bind;
88
89 // If 'symmetric' is a symmetric block cipher (not TPM_ALG_NULL or TPM_ALG_XOR)
90 // then the mode must be CFB.
91 if( in->symmetric.algorithm != TPM_ALG_NULL
92 && in->symmetric.algorithm != TPM_ALG_XOR
93 && in->symmetric.mode.sym != TPM_ALG_CFB)
94 return TPM_RC_MODE + RC_StartAuthSession_symmetric;
95
96 // Internal Data Update
97
98 // Create internal session structure. TPM_RC_CONTEXT_GAP, TPM_RC_NO_HANDLES
99 // or TPM_RC_SESSION_MEMORY errors may be returned returned at this point.
100 //
101 // The detailed actions for creating the session context are not shown here
102 // as the details are implementation dependent
103 // SessionCreate sets the output handle
104 result = SessionCreate(in->sessionType, in->authHash,
105 &in->nonceCaller, &in->symmetric,
106 in->bind, &salt, &out->sessionHandle);
107
108 if(result != TPM_RC_SUCCESS)
109 return result;
110
111 // Command Output
112
113 // Get session pointer
114 session = SessionGet(out->sessionHandle);
115
116 // Copy nonceTPM
117 out->nonceTPM = session->nonceTPM;
118
119 return TPM_RC_SUCCESS;
120 }
121