Added pausable to Pool actions and aTokens at transfer, triggered by LendingPoolConfigurator. Added basic test to aToken transfer.

contracts/interfaces/ILendingPool.sol

@@ -129,6 +129,15 @@ interface ILendingPool {
     address liquidator,
     bool receiveAToken
   );
+  /**
+   * @dev Emitted when the pause is triggered by `account`.
+   */
+  event Paused(address account);
+
+  /**
+   * @dev Emitted when the pause is lifted by `account`.
+   */
+  event Unpaused(address account);
 
   /**
    * @dev deposits The underlying asset into the reserve. A corresponding amount of the overlying asset (aTokens)
@@ -374,4 +383,10 @@ interface ILendingPool {
   ) external view returns (bool);
 
   function getReserves() external view returns (address[] memory);
+
+  function pause() external;
+
+  function unpause() external;
+
+  function isPaused() external view returns (bool);
 }

contracts/lendingpool/LendingPool.sol

@@ -4,6 +4,7 @@ pragma experimental ABIEncoderV2;
 
 import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';
 import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';
+import {Pausable} from '@openzeppelin/contracts/utils/Pausable.sol';
 import {
   VersionedInitializable
 } from '../libraries/openzeppelin-upgradeability/VersionedInitializable.sol';
@@ -31,7 +32,7 @@ import {ILendingPool} from '../interfaces/ILendingPool.sol';
  * @author Aave
  **/
 
-contract LendingPool is VersionedInitializable, ILendingPool {
+contract LendingPool is VersionedInitializable, Pausable, ILendingPool {
   using SafeMath for uint256;
   using WadRayMath for uint256;
   using ReserveLogic for ReserveLogic.ReserveData;
@@ -93,7 +94,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     uint256 amount,
     address onBehalfOf,
     uint16 referralCode
-  ) external override {
+  ) external override whenNotPaused {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     ValidationLogic.validateDeposit(reserve, amount);
@@ -121,7 +122,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
    * @param asset the address of the reserve
    * @param amount the underlying amount to be redeemed
    **/
-  function withdraw(address asset, uint256 amount) external override {
+  function withdraw(address asset, uint256 amount) external override whenNotPaused {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     address aToken = reserve.aTokenAddress;
@@ -172,7 +173,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     uint256 amount,
     uint256 interestRateMode,
     uint16 referralCode
-  ) external override {
+  ) external override whenNotPaused {
     _executeBorrow(
       ExecuteBorrowParams(
         asset,
@@ -199,7 +200,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     uint256 amount,
     uint256 rateMode,
     address onBehalfOf
-  ) external override {
+  ) external override whenNotPaused {
     _executeRepay(asset, msg.sender, amount, rateMode, onBehalfOf);
   }
 
@@ -260,7 +261,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
    * @param asset the address of the reserve on which the user borrowed
    * @param rateMode the rate mode that the user wants to swap
    **/
-  function swapBorrowRateMode(address asset, uint256 rateMode) external override {
+  function swapBorrowRateMode(address asset, uint256 rateMode) external override whenNotPaused {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     (uint256 stableDebt, uint256 variableDebt) = Helpers.getUserCurrentDebt(msg.sender, reserve);
@@ -303,7 +304,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
    * @param asset the address of the reserve
    * @param user the address of the user to be rebalanced
    **/
-  function rebalanceStableBorrowRate(address asset, address user) external override {
+  function rebalanceStableBorrowRate(address asset, address user) external override whenNotPaused {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     IStableDebtToken stableDebtToken = IStableDebtToken(reserve.stableDebtTokenAddress);
@@ -348,7 +349,11 @@ contract LendingPool is VersionedInitializable, ILendingPool {
    * @param asset the address of the reserve
    * @param useAsCollateral true if the user wants to user the deposit as collateral, false otherwise.
    **/
-  function setUserUseReserveAsCollateral(address asset, bool useAsCollateral) external override {
+  function setUserUseReserveAsCollateral(address asset, bool useAsCollateral)
+    external
+    override
+    whenNotPaused
+  {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
 
     ValidationLogic.validateSetUseReserveAsCollateral(
@@ -384,7 +389,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     address user,
     uint256 purchaseAmount,
     bool receiveAToken
-  ) external override {
+  ) external override whenNotPaused {
     address liquidationManager = _addressesProvider.getLendingPoolLiquidationManager();
 
     //solium-disable-next-line
@@ -440,7 +445,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     uint256 principalAmount,
     address receiver,
     bytes calldata params
-  ) external override {
+  ) external override whenNotPaused {
     require(!_flashLiquidationLocked, Errors.REENTRANCY_NOT_ALLOWED);
     _flashLiquidationLocked = true;
 
@@ -487,7 +492,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     uint256 mode,
     bytes calldata params,
     uint16 referralCode
-  ) external override {
+  ) external override whenNotPaused {
     ReserveLogic.ReserveData storage reserve = _reserves[asset];
     FlashLoanLocalVars memory vars;
 
@@ -706,7 +711,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     address stableDebtAddress,
     address variableDebtAddress,
     address interestRateStrategyAddress
-  ) external override onlyLendingPoolConfigurator {
+  ) external override onlyLendingPoolConfigurator whenNotPaused {
     _reserves[asset].init(
       aTokenAddress,
       stableDebtAddress,
@@ -726,6 +731,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     external
     override
     onlyLendingPoolConfigurator
+    whenNotPaused
   {
     _reserves[asset].interestRateStrategyAddress = rateStrategyAddress;
   }
@@ -908,4 +914,25 @@ contract LendingPool is VersionedInitializable, ILendingPool {
   function getAddressesProvider() external view returns (ILendingPoolAddressesProvider) {
     return _addressesProvider;
   }
+
+  /**
+   * @dev pause all the Lending Pool actions
+   */
+  function pause() external override onlyLendingPoolConfigurator {
+    _pause();
+  }
+
+  /**
+   * @dev unpause all the Lending Pool actions
+   */
+  function unpause() external override onlyLendingPoolConfigurator {
+    _unpause();
+  }
+
+  /**
+   * @dev Returns true if the contract is paused, and false otherwise.
+   */
+  function isPaused() public override view returns (bool) {
+    return Pausable.paused();
+  }
 }

contracts/lendingpool/LendingPoolConfigurator.sol

@@ -582,4 +582,18 @@ contract LendingPoolConfigurator is VersionedInitializable {
 
     proxy.upgradeToAndCall(implementation, params);
   }
+
+  /**
+   * @dev pauses LendingPool actions
+   **/
+  function pausePool() external onlyLendingPoolManager {
+    pool.pause();
+  }
+
+  /**
+   * @dev unpauses LendingPool actions
+   **/
+  function unpausePool() external onlyLendingPoolManager {
+    pool.unpause();
+  }
 }

contracts/tokenization/AToken.sol

@@ -67,7 +67,6 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     uint256 amount,
     uint256 index
   ) external override onlyLendingPool {
-
     uint256 currentBalance = balanceOf(user);
 
     require(amount <= currentBalance, Errors.INVALID_ATOKEN_BALANCE);
@@ -79,7 +78,6 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     //transfers the underlying to the target
     ERC20(UNDERLYING_ASSET_ADDRESS).safeTransfer(receiverOfUnderlying, amount);
 
-
     emit Burn(msg.sender, receiverOfUnderlying, amount, index);
   }
 
@@ -89,13 +87,15 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
    * @param user the address receiving the minted tokens
    * @param amount the amount of tokens to mint
    */
-  function mint(address user, uint256 amount, uint256 index) external override onlyLendingPool {
-
-
+  function mint(
+    address user,
+    uint256 amount,
+    uint256 index
+  ) external override onlyLendingPool {
     uint256 scaledAmount = amount.rayDiv(index);
- 
+
     //mint an equivalent amount of tokens to cover the new deposit
-    _mint(user,scaledAmount);
+    _mint(user, scaledAmount);
 
     emit Mint(user, amount, index);
   }
@@ -119,7 +119,7 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
 
   /**
    * @dev calculates the balance of the user, which is the
-   * principal balance + interest generated by the principal balance 
+   * principal balance + interest generated by the principal balance
    * @param user the user for which the balance is being calculated
    * @return the total balance of the user
    **/
@@ -150,9 +150,7 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
       return 0;
     }
 
-    return
-      currentSupplyScaled
-        .rayMul(POOL.getReserveNormalizedIncome(UNDERLYING_ASSET_ADDRESS));
+    return currentSupplyScaled.rayMul(POOL.getReserveNormalizedIncome(UNDERLYING_ASSET_ADDRESS));
   }
 
   /**
@@ -162,16 +160,16 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
    * @return true if the user can transfer amount, false otherwise
    **/
   function isTransferAllowed(address user, uint256 amount) public override view returns (bool) {
-    return POOL.balanceDecreaseAllowed(UNDERLYING_ASSET_ADDRESS, user, amount);
+    return !POOL.isPaused() && POOL.balanceDecreaseAllowed(UNDERLYING_ASSET_ADDRESS, user, amount);
   }
 
   /**
-  * @dev transfers the underlying asset to the target. Used by the lendingpool to transfer
-  * assets in borrow(), redeem() and flashLoan()
-  * @param target the target of the transfer
-  * @param amount the amount to transfer
-  * @return the amount transferred
-  **/
+   * @dev transfers the underlying asset to the target. Used by the lendingpool to transfer
+   * assets in borrow(), redeem() and flashLoan()
+   * @param target the target of the transfer
+   * @param amount the amount to transfer
+   * @return the amount transferred
+   **/
   function transferUnderlyingTo(address target, uint256 amount)
     external
     override
@@ -187,8 +185,8 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     address to,
     uint256 amount,
     bool validate
-  ) internal  {
-    if(validate){
+  ) internal {
+    if (validate) {
       require(isTransferAllowed(from, amount), Errors.TRANSFER_NOT_ALLOWED);
     }
 
@@ -199,17 +197,16 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     super._transfer(from, to, scaledAmount);
 
     emit BalanceTransfer(from, to, amount, index);
-
   }
-  
+
   function _transfer(
     address from,
     address to,
     uint256 amount
-    ) internal override {
-
-      _transfer(from, to, amount, true);
+  ) internal override {
+    _transfer(from, to, amount, true);
   }
+
   /**
    * @dev aTokens should not receive ETH
    **/

package.json

@@ -15,6 +15,7 @@
     "test-scenarios": "buidler test test/__setup.spec.ts test/scenario.spec.ts",
     "test-repay-with-collateral": "buidler test test/__setup.spec.ts test/repay-with-collateral.spec.ts",
     "test-liquidate-with-collateral": "buidler test test/__setup.spec.ts test/flash-liquidation-with-collateral.spec.ts",
+    "test-transfers": "buidler test test/__setup.spec.ts test/atoken-transfer.spec.ts",
     "test-flash": "buidler test test/__setup.spec.ts test/flashloan.spec.ts",
     "dev:coverage": "buidler coverage --network coverage",
     "dev:deployment": "buidler dev-deployment",

test/atoken-transfer.spec.ts

@@ -45,7 +45,6 @@ makeSuite('AToken: Transfer', (testEnv: TestEnv) => {
     );
   });
 
-
   it('User 0 deposits 1 WETH and user 1 tries to borrow, but the aTokens received as a transfer are not available as collateral (revert expected)', async () => {
     const {users, pool, weth} = testEnv;
     const userAddress = await pool.signer.getAddress();
@@ -81,4 +80,58 @@ makeSuite('AToken: Transfer', (testEnv: TestEnv) => {
     ).to.be.revertedWith(TRANSFER_NOT_ALLOWED);
   });
 
+  it('User 0 deposits 1000 DAI. Configurator pauses pool. Transfers to user 1 reverts. Configurator unpauses the network and next transfer succees', async () => {
+    const {users, pool, dai, aDai, configurator} = testEnv;
+
+    const amountDAItoDeposit = await convertToCurrencyDecimals(dai.address, '1000');
+
+    await dai.connect(users[0].signer).mint(amountDAItoDeposit);
+
+    // user 0 deposits 1000 DAI
+    await dai.connect(users[0].signer).approve(pool.address, APPROVAL_AMOUNT_LENDING_POOL);
+    await pool
+      .connect(users[0].signer)
+      .deposit(dai.address, amountDAItoDeposit, users[0].address, '0');
+
+    const user0Balance = await aDai.balanceOf(users[0].address);
+    const user1Balance = await aDai.balanceOf(users[1].address);
+
+    // Configurator pauses the pool
+    await configurator.pausePool();
+
+    // User 0 tries the transfer to User 1
+    await expect(
+      aDai.connect(users[0].signer).transfer(users[1].address, amountDAItoDeposit)
+    ).to.revertedWith(TRANSFER_NOT_ALLOWED);
+
+    const pausedFromBalance = await aDai.balanceOf(users[0].address);
+    const pausedToBalance = await aDai.balanceOf(users[1].address);
+
+    expect(pausedFromBalance).to.be.equal(
+      user0Balance.toString(),
+      INVALID_TO_BALANCE_AFTER_TRANSFER
+    );
+    expect(pausedToBalance.toString()).to.be.equal(
+      user1Balance.toString(),
+      INVALID_FROM_BALANCE_AFTER_TRANSFER
+    );
+
+    // Configurator unpauses the pool
+    await configurator.unpausePool();
+
+    // User 0 succeeds transfer to User 1
+    await aDai.connect(users[0].signer).transfer(users[1].address, amountDAItoDeposit);
+
+    const fromBalance = await aDai.balanceOf(users[0].address);
+    const toBalance = await aDai.balanceOf(users[1].address);
+
+    expect(fromBalance.toString()).to.be.equal(
+      user0Balance.sub(amountDAItoDeposit),
+      INVALID_FROM_BALANCE_AFTER_TRANSFER
+    );
+    expect(toBalance.toString()).to.be.equal(
+      user1Balance.add(amountDAItoDeposit),
+      INVALID_TO_BALANCE_AFTER_TRANSFER
+    );
+  });
 });