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      1 //
      2 // Copyright (C) 2015 The Android Open Source Project
      3 //
      4 // Licensed under the Apache License, Version 2.0 (the "License");
      5 // you may not use this file except in compliance with the License.
      6 // You may obtain a copy of the License at
      7 //
      8 //      http://www.apache.org/licenses/LICENSE-2.0
      9 //
     10 // Unless required by applicable law or agreed to in writing, software
     11 // distributed under the License is distributed on an "AS IS" BASIS,
     12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13 // See the License for the specific language governing permissions and
     14 // limitations under the License.
     15 //
     16 
     17 #include "tpm_manager/server/tpm_status_impl.h"
     18 
     19 #include <vector>
     20 
     21 #include <base/logging.h>
     22 #include <trousers/tss.h>
     23 #include <trousers/trousers.h>  // NOLINT(build/include_alpha)
     24 
     25 namespace tpm_manager {
     26 
     27 // Minimum size of TPM_DA_INFO struct.
     28 const size_t kMinimumDaInfoSize = 21;
     29 
     30 bool TpmStatusImpl::IsTpmEnabled() {
     31   if (!is_enable_initialized_) {
     32     RefreshOwnedEnabledInfo();
     33   }
     34   return is_enabled_;
     35 }
     36 
     37 bool TpmStatusImpl::IsTpmOwned() {
     38   if (!is_owned_) {
     39     RefreshOwnedEnabledInfo();
     40   }
     41   return is_owned_;
     42 }
     43 
     44 bool TpmStatusImpl::GetDictionaryAttackInfo(int* counter,
     45                                             int* threshold,
     46                                             bool* lockout,
     47                                             int* seconds_remaining) {
     48   std::string capability_data;
     49   if (!GetCapability(TSS_TPMCAP_DA_LOGIC, TPM_ET_KEYHANDLE,
     50                      &capability_data, nullptr) ||
     51       capability_data.size() < kMinimumDaInfoSize) {
     52     LOG(ERROR) << "Error getting tpm capability data.";
     53     return false;
     54   }
     55   if (static_cast<uint16_t>(capability_data[1]) == TPM_TAG_DA_INFO) {
     56     TPM_DA_INFO da_info;
     57     uint64_t offset = 0;
     58     std::vector<BYTE> bytes(capability_data.begin(), capability_data.end());
     59     Trspi_UnloadBlob_DA_INFO(&offset, bytes.data(), &da_info);
     60     if (counter) { *counter = da_info.currentCount; }
     61     if (threshold) { *threshold = da_info.thresholdCount; }
     62     if (lockout) { *lockout = (da_info.state == TPM_DA_STATE_ACTIVE); }
     63     if (seconds_remaining) { *seconds_remaining = da_info.actionDependValue; }
     64   }
     65   return true;
     66 }
     67 
     68 void TpmStatusImpl::RefreshOwnedEnabledInfo() {
     69   TSS_RESULT result;
     70   std::string capability_data;
     71   if (!GetCapability(TSS_TPMCAP_PROPERTY, TSS_TPMCAP_PROP_OWNER,
     72                      &capability_data, &result)) {
     73     if (ERROR_CODE(result) == TPM_E_DISABLED) {
     74       is_enable_initialized_ = true;
     75       is_enabled_ = false;
     76     }
     77   } else {
     78     is_enable_initialized_ = true;
     79     is_enabled_ = true;
     80     // |capability_data| should be populated with a TSS_BOOL which is true iff
     81     // the Tpm is owned.
     82     if (capability_data.size() != sizeof(TSS_BOOL)) {
     83       LOG(ERROR) << "Error refreshing Tpm ownership information.";
     84       return;
     85     }
     86     is_owned_ = (capability_data[0] != 0);
     87   }
     88 }
     89 
     90 bool TpmStatusImpl::GetCapability(uint32_t capability,
     91                                   uint32_t sub_capability,
     92                                   std::string* data,
     93                                   TSS_RESULT* tpm_result) {
     94   CHECK(data);
     95   TSS_HTPM tpm_handle = tpm_connection_.GetTpm();
     96   if (tpm_handle == 0) {
     97     return false;
     98   }
     99   uint32_t length = 0;
    100   trousers::ScopedTssMemory buf(tpm_connection_.GetContext());
    101   TSS_RESULT result = Tspi_TPM_GetCapability(
    102       tpm_handle, capability, sizeof(uint32_t),
    103       reinterpret_cast<BYTE*>(&sub_capability),
    104       &length, buf.ptr());
    105   if (tpm_result) {
    106     *tpm_result = result;
    107   }
    108   if (TPM_ERROR(result)) {
    109     LOG(ERROR) << "Error getting TPM capability data.";
    110     return false;
    111   }
    112   data->assign(buf.value(), buf.value() + length);
    113   return true;
    114 }
    115 
    116 }  // namespace tpm_manager
    117