server/FirewallController.h

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef _FIREWALL_CONTROLLER_H
#define _FIREWALL_CONTROLLER_H

#include <mutex>
#include <set>
#include <string>
#include <vector>

#include "NetdConstants.h"

enum FirewallRule { DENY, ALLOW };

// WHITELIST means the firewall denies all by default, uids must be explicitly ALLOWed
// BLACKLIST means the firewall allows all by default, uids must be explicitly DENYed

enum FirewallType { WHITELIST, BLACKLIST };

enum ChildChain { NONE, DOZABLE, STANDBY, POWERSAVE, INVALID_CHAIN };

/*
 * Simple firewall that drops all packets except those matching explicitly
 * defined ALLOW rules.
 *
 * Methods in this class must be called when holding a write lock on |lock|, and may not call
 * any other controller without explicitly managing that controller's lock. There are currently
 * no such methods.
 */
class FirewallController {
public:
    FirewallController();

    int setupIptablesHooks(void);

    int enableFirewall(FirewallType);
    int disableFirewall(void);
    int isFirewallEnabled(void);

    /* Match traffic going in/out over the given iface. */
    int setInterfaceRule(const char*, FirewallRule);
    /* Match traffic owned by given UID. This is specific to a particular chain. */
    int setUidRule(ChildChain, int, FirewallRule);

    int enableChildChains(ChildChain, bool);

    int replaceUidChain(const std::string&, bool, const std::vector<int32_t>&);

    static std::string makeCriticalCommands(IptablesTarget target, const char* chainName);

    static const char* TABLE;

    static const char* LOCAL_INPUT;
    static const char* LOCAL_OUTPUT;
    static const char* LOCAL_FORWARD;

    static const char* LOCAL_DOZABLE;
    static const char* LOCAL_STANDBY;
    static const char* LOCAL_POWERSAVE;

    static const char* ICMPV6_TYPES[];

    std::mutex lock;

protected:
    friend class FirewallControllerTest;
    std::string makeUidRules(IptablesTarget target, const char *name, bool isWhitelist,
                             const std::vector<int32_t>& uids);
    static int (*execIptablesRestore)(IptablesTarget target, const std::string& commands);

private:
    FirewallType mFirewallType;
    bool mUseBpfOwnerMatch;
    std::set<std::string> mIfaceRules;
    int attachChain(const char*, const char*);
    int detachChain(const char*, const char*);
    int createChain(const char*, FirewallType);
    FirewallType getFirewallType(ChildChain);
};

#endif