Merge cherrypicks of ['googleplex-android-review.googlesource.com/27059672', 'googleplex-android-review.googlesource.com/27059673', 'googleplex-android-review.googlesource.com/27059674'] into security-aosp-tm-release.

Change-Id: I258b76a297137d025a8883a621164a6301aeed66
diff --git a/system/btif/src/btif_storage.cc b/system/btif/src/btif_storage.cc
index 41fa4df..ae81bd1 100644
--- a/system/btif/src/btif_storage.cc
+++ b/system/btif/src/btif_storage.cc
@@ -92,10 +92,13 @@
 #define BTIF_STORAGE_KEY_ADAPTER_SCANMODE "ScanMode"
 #define BTIF_STORAGE_KEY_LOCAL_IO_CAPS "LocalIOCaps"
 #define BTIF_STORAGE_KEY_LOCAL_IO_CAPS_BLE "LocalIOCapsBLE"
+#define BTIF_STORAGE_KEY_MAX_SESSION_KEY_SIZE "MaxSessionKeySize"
 #define BTIF_STORAGE_KEY_ADAPTER_DISC_TIMEOUT "DiscoveryTimeout"
 #define BTIF_STORAGE_KEY_GATT_CLIENT_SUPPORTED "GattClientSupportedFeatures"
 #define BTIF_STORAGE_KEY_GATT_CLIENT_DB_HASH "GattClientDatabaseHash"
 #define BTIF_STORAGE_KEY_GATT_SERVER_SUPPORTED "GattServerSupportedFeatures"
+#define BTIF_STORAGE_KEY_SECURE_CONNECTIONS_SUPPORTED \
+  "SecureConnectionsSupported"
 #define BTIF_STORAGE_DEVICE_GROUP_BIN "DeviceGroupBin"
 #define BTIF_STORAGE_CSIS_AUTOCONNECT "CsisAutoconnect"
 #define BTIF_STORAGE_CSIS_SET_INFO_BIN "CsisSetInfoBin"
@@ -281,6 +284,14 @@
       btif_config_set_int(bdstr, BT_CONFIG_KEY_REMOTE_VER_SUBVER,
                           info->sub_ver);
     } break;
+    case BT_PROPERTY_REMOTE_SECURE_CONNECTIONS_SUPPORTED:
+      btif_config_set_int(bdstr, BTIF_STORAGE_KEY_SECURE_CONNECTIONS_SUPPORTED,
+                          *(uint8_t*)prop->val);
+      break;
+    case BT_PROPERTY_REMOTE_MAX_SESSION_KEY_SIZE:
+      btif_config_set_int(bdstr, BTIF_STORAGE_KEY_MAX_SESSION_KEY_SIZE,
+                          *(uint8_t*)prop->val);
+      break;
 
     default:
       BTIF_TRACE_ERROR("Unknown prop type:%d", prop->type);
@@ -407,6 +418,26 @@
       }
     } break;
 
+    case BT_PROPERTY_REMOTE_SECURE_CONNECTIONS_SUPPORTED: {
+      int val;
+
+      if (prop->len >= (int)sizeof(uint8_t)) {
+        ret = btif_config_get_int(
+            bdstr, BTIF_STORAGE_KEY_SECURE_CONNECTIONS_SUPPORTED, &val);
+        *(uint8_t*)prop->val = (uint8_t)val;
+      }
+    } break;
+
+    case BT_PROPERTY_REMOTE_MAX_SESSION_KEY_SIZE: {
+      int val;
+
+      if (prop->len >= (int)sizeof(uint8_t)) {
+        ret = btif_config_get_int(bdstr, BTIF_STORAGE_KEY_MAX_SESSION_KEY_SIZE,
+                                  &val);
+        *(uint8_t*)prop->val = (uint8_t)val;
+      }
+    } break;
+
     default:
       BTIF_TRACE_ERROR("Unknow prop type:%d", prop->type);
       return false;
diff --git a/system/include/hardware/bluetooth.h b/system/include/hardware/bluetooth.h
index 96e425c..81a4108 100644
--- a/system/include/hardware/bluetooth.h
+++ b/system/include/hardware/bluetooth.h
@@ -339,6 +339,20 @@
    */
   BT_PROPERTY_REMOTE_IS_COORDINATED_SET_MEMBER,
 
+  /**
+   * Description - Whether remote device supports Secure Connections mode
+   * Access mode - GET and SET.
+   * Data Type - uint8_t.
+   */
+  BT_PROPERTY_REMOTE_SECURE_CONNECTIONS_SUPPORTED,
+
+  /**
+   * Description - Maximum observed session key for remote device
+   * Access mode - GET and SET.
+   * Data Type - uint8_t.
+   */
+  BT_PROPERTY_REMOTE_MAX_SESSION_KEY_SIZE,
+
   BT_PROPERTY_REMOTE_DEVICE_TIMESTAMP = 0xFF,
 } bt_property_type_t;
 
diff --git a/system/service/logging_helpers.cc b/system/service/logging_helpers.cc
index 78a24e6..0c3644d 100644
--- a/system/service/logging_helpers.cc
+++ b/system/service/logging_helpers.cc
@@ -118,6 +118,8 @@
     CASE_RETURN_TEXT(BT_PROPERTY_REMOTE_VERSION_INFO);
     CASE_RETURN_TEXT(BT_PROPERTY_LOCAL_LE_FEATURES);
     CASE_RETURN_TEXT(BT_PROPERTY_REMOTE_DEVICE_TIMESTAMP);
+    CASE_RETURN_TEXT(BT_PROPERTY_REMOTE_SECURE_CONNECTIONS_SUPPORTED);
+    CASE_RETURN_TEXT(BT_PROPERTY_REMOTE_MAX_SESSION_KEY_SIZE);
     default:
       return "Invalid property";
   }
diff --git a/system/stack/btm/btm_sec.cc b/system/stack/btm/btm_sec.cc
index 6ec6d16..73c98aa 100644
--- a/system/stack/btm/btm_sec.cc
+++ b/system/stack/btm/btm_sec.cc
@@ -209,6 +209,109 @@
 
 /*******************************************************************************
  *
+ * Function         btm_sec_is_device_sc_downgrade
+ *
+ * Description      Check for a stored device record matching the candidate
+ *                  device, and return true if the stored device has reported
+ *                  that it supports Secure Connections mode and the candidate
+ *                  device reports that it does not.  Otherwise, return false.
+ *
+ * Returns          bool
+ *
+ ******************************************************************************/
+static bool btm_sec_is_device_sc_downgrade(uint16_t hci_handle,
+                                           bool secure_connections_supported) {
+  if (secure_connections_supported) return false;
+
+  tBTM_SEC_DEV_REC* p_dev_rec = btm_find_dev_by_handle(hci_handle);
+  if (p_dev_rec == nullptr) return false;
+
+  uint8_t property_val = 0;
+  bt_property_t property = {
+      .type = BT_PROPERTY_REMOTE_SECURE_CONNECTIONS_SUPPORTED,
+      .len = sizeof(uint8_t),
+      .val = &property_val};
+
+  bt_status_t cached =
+      btif_storage_get_remote_device_property(&p_dev_rec->bd_addr, &property);
+
+  if (cached == BT_STATUS_FAIL) return false;
+
+  return (bool)property_val;
+}
+
+/*******************************************************************************
+ *
+ * Function         btm_sec_store_device_sc_support
+ *
+ * Description      Save Secure Connections support for this device to file
+ *
+ ******************************************************************************/
+
+static void btm_sec_store_device_sc_support(uint16_t hci_handle,
+                                            bool secure_connections_supported) {
+  tBTM_SEC_DEV_REC* p_dev_rec = btm_find_dev_by_handle(hci_handle);
+  if (p_dev_rec == nullptr) return;
+
+  uint8_t property_val = (uint8_t)secure_connections_supported;
+  bt_property_t property = {
+      .type = BT_PROPERTY_REMOTE_SECURE_CONNECTIONS_SUPPORTED,
+      .len = sizeof(uint8_t),
+      .val = &property_val};
+
+  btif_storage_set_remote_device_property(&p_dev_rec->bd_addr, &property);
+}
+
+/*******************************************************************************
+ *
+ * Function         btm_sec_is_session_key_size_downgrade
+ *
+ * Description      Check if there is a stored device record matching this
+ *                  handle, and return true if the stored record has a lower
+ *                  session key size than the candidate device.
+ *
+ * Returns          bool
+ *
+ ******************************************************************************/
+bool btm_sec_is_session_key_size_downgrade(uint16_t hci_handle,
+                                           uint8_t key_size) {
+  tBTM_SEC_DEV_REC* p_dev_rec = btm_find_dev_by_handle(hci_handle);
+  if (p_dev_rec == nullptr) return false;
+
+  uint8_t property_val = 0;
+  bt_property_t property = {.type = BT_PROPERTY_REMOTE_MAX_SESSION_KEY_SIZE,
+                            .len = sizeof(uint8_t),
+                            .val = &property_val};
+
+  bt_status_t cached =
+      btif_storage_get_remote_device_property(&p_dev_rec->bd_addr, &property);
+
+  if (cached == BT_STATUS_FAIL) return false;
+
+  return property_val > key_size;
+}
+
+/*******************************************************************************
+ *
+ * Function         btm_sec_update_session_key_size
+ *
+ * Description      Store the max session key size to disk, if possible.
+ *
+ ******************************************************************************/
+void btm_sec_update_session_key_size(uint16_t hci_handle, uint8_t key_size) {
+  tBTM_SEC_DEV_REC* p_dev_rec = btm_find_dev_by_handle(hci_handle);
+  if (p_dev_rec == nullptr) return;
+
+  uint8_t property_val = key_size;
+  bt_property_t property = {.type = BT_PROPERTY_REMOTE_MAX_SESSION_KEY_SIZE,
+                            .len = sizeof(uint8_t),
+                            .val = &property_val};
+
+  btif_storage_set_remote_device_property(&p_dev_rec->bd_addr, &property);
+}
+
+/*******************************************************************************
+ *
  * Function         access_secure_service_from_temp_bond
  *
  * Description      a utility function to test whether an access to
@@ -3974,6 +4077,13 @@
     }
   }
 
+  if (p_dev_rec->is_bond_type_persistent() &&
+      (p_dev_rec->is_device_type_br_edr() ||
+       p_dev_rec->is_device_type_dual_mode())) {
+    btm_sec_store_device_sc_support(p_dev_rec->get_br_edr_hci_handle(),
+                                    p_dev_rec->SupportsSecureConnections());
+  }
+
   /* If name is not known at this point delay calling callback until the name is
    */
   /* resolved. Unless it is a HID Device and we really need to send all link
@@ -5050,6 +5160,16 @@
   tBTM_SEC_DEV_REC* p_dev_rec = btm_find_dev_by_handle(hci_handle);
   if (p_dev_rec == nullptr) return;
 
+  // Drop the connection here if the remote attempts to downgrade from Secure
+  // Connections mode.
+  if (btm_sec_is_device_sc_downgrade(hci_handle, sc_supported)) {
+    acl_set_disconnect_reason(HCI_ERR_HOST_REJECT_SECURITY);
+    btm_sec_send_hci_disconnect(
+        p_dev_rec, HCI_ERR_AUTH_FAILURE, hci_handle,
+        "attempted to downgrade from Secure Connections mode");
+    return;
+  }
+
   p_dev_rec->remote_feature_received = true;
   p_dev_rec->remote_supports_hci_role_switch = hci_role_switch_supported;
 
diff --git a/system/stack/btm/btm_sec.h b/system/stack/btm/btm_sec.h
index 8b92d5d..a48dbb2 100644
--- a/system/stack/btm/btm_sec.h
+++ b/system/stack/btm/btm_sec.h
@@ -805,5 +805,28 @@
 void btm_sec_cr_loc_oob_data_cback_event(const RawAddress& address,
                                          tSMP_LOC_OOB_DATA loc_oob_data);
 
+/*******************************************************************************
+ *
+ * Function         btm_sec_is_session_key_size_downgrade
+ *
+ * Description      Check if there is a stored device record matching this
+ *                  handle, and return true if the stored record has a lower
+ *                  session key size than the candidate device.
+ *
+ * Returns          bool
+ *
+ ******************************************************************************/
+bool btm_sec_is_session_key_size_downgrade(uint16_t hci_handle,
+                                           uint8_t key_size);
+
+/*******************************************************************************
+ *
+ * Function         btm_sec_update_session_key_size
+ *
+ * Description      Store the max session key size to disk, if possible.
+ *
+ ******************************************************************************/
+void btm_sec_update_session_key_size(uint16_t hci_handle, uint8_t key_size);
+
 // Return DEV_CLASS (uint8_t[3]) of bda. If record doesn't exist, create one.
 const uint8_t* btm_get_dev_class(const RawAddress& bda);
diff --git a/system/stack/btu/btu_hcif.cc b/system/stack/btu/btu_hcif.cc
index 9c31772..6a4aecd 100644
--- a/system/stack/btu/btu_hcif.cc
+++ b/system/stack/btu/btu_hcif.cc
@@ -1038,6 +1038,20 @@
     return;
   }
 
+  if (btm_sec_is_session_key_size_downgrade(handle, key_size)) {
+    LOG_ERROR(
+        "encryption key size lower than cached value, disconnecting. "
+        "handle: 0x%x attempted key size: %d",
+        handle, key_size);
+    acl_disconnect_from_handle(
+        handle, HCI_ERR_HOST_REJECT_SECURITY,
+        "stack::btu::btu_hcif::read_encryption_key_size_complete_after_"
+        "encryption_change Key Size Downgrade");
+    return;
+  }
+
+  btm_sec_update_session_key_size(handle, key_size);
+
   // good key size - succeed
   btm_acl_encrypt_change(handle, static_cast<tHCI_STATUS>(status),
                          1 /* enable */);
diff --git a/system/stack/include/sec_hci_link_interface.h b/system/stack/include/sec_hci_link_interface.h
index b5dda7f..6d859fd 100644
--- a/system/stack/include/sec_hci_link_interface.h
+++ b/system/stack/include/sec_hci_link_interface.h
@@ -37,6 +37,8 @@
 void btm_sec_disconnected(uint16_t handle, tHCI_STATUS reason, std::string);
 void btm_sec_encrypt_change(uint16_t handle, tHCI_STATUS status,
                             uint8_t encr_enable);
+bool btm_sec_is_session_key_size_downgrade(uint16_t hci_handle,
+                                           uint8_t key_size);
 void btm_sec_link_key_notification(const RawAddress& p_bda,
                                    const Octet16& link_key, uint8_t key_type);
 void btm_sec_link_key_request(const uint8_t* p_event);
@@ -46,4 +48,5 @@
                                        const uint8_t* bd_name,
                                        tHCI_STATUS status);
 void btm_sec_update_clock_offset(uint16_t handle, uint16_t clock_offset);
+void btm_sec_update_session_key_size(uint16_t hci_handle, uint8_t key_size);
 void btm_simple_pair_complete(const uint8_t* p);
diff --git a/system/test/mock/mock_stack_btm_sec.cc b/system/test/mock/mock_stack_btm_sec.cc
index 56a0db1..7b5f9e4 100644
--- a/system/test/mock/mock_stack_btm_sec.cc
+++ b/system/test/mock/mock_stack_btm_sec.cc
@@ -113,6 +113,11 @@
   mock_function_count_map[__func__]++;
   return false;
 }
+bool btm_sec_is_session_key_size_downgrade(uint16_t hci_handle,
+                                           uint8_t key_size) {
+  mock_function_count_map[__func__]++;
+  return false;
+}
 bool is_sec_state_equal(void* data, void* context) {
   mock_function_count_map[__func__]++;
   return false;
@@ -313,6 +318,9 @@
 void btm_sec_update_clock_offset(uint16_t handle, uint16_t clock_offset) {
   mock_function_count_map[__func__]++;
 }
+void btm_sec_update_session_key_size(uint16_t hci_handle, uint8_t key_size) {
+  mock_function_count_map[__func__]++;
+}
 void btm_simple_pair_complete(const uint8_t* p) {
   mock_function_count_map[__func__]++;
 }