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/*
* 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 <sys/types.h>
#include <mutex>
#include <set>
#include <string>
#include <vector>
#include "android/net/INetd.h"
#include "NetdConstants.h"
#include "bpf/BpfUtils.h"
namespace android {
namespace net {
enum FirewallRule { ALLOW = INetd::FIREWALL_RULE_ALLOW, DENY = INetd::FIREWALL_RULE_DENY };
// ALLOWLIST means the firewall denies all by default, uids must be explicitly ALLOWed
// DENYLIST means the firewall allows all by default, uids must be explicitly DENYed
enum FirewallType { ALLOWLIST = INetd::FIREWALL_ALLOWLIST, DENYLIST = INetd::FIREWALL_DENYLIST };
enum ChildChain {
NONE = INetd::FIREWALL_CHAIN_NONE,
DOZABLE = INetd::FIREWALL_CHAIN_DOZABLE,
STANDBY = INetd::FIREWALL_CHAIN_STANDBY,
POWERSAVE = INetd::FIREWALL_CHAIN_POWERSAVE,
RESTRICTED = INetd::FIREWALL_CHAIN_RESTRICTED,
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 setFirewallType(FirewallType);
int resetFirewall(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 uid_t discoverMaximumValidUid(const std::string& fileName);
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* LOCAL_RESTRICTED;
static const char* ICMPV6_TYPES[];
std::mutex lock;
protected:
friend class FirewallControllerTest;
std::string makeUidRules(IptablesTarget target, const char* name, bool isAllowlist,
const std::vector<int32_t>& uids);
static int (*execIptablesRestore)(IptablesTarget target, const std::string& commands);
private:
// Netd supports two cases, in both of which mMaxUid that derives from the uid mapping is const:
// - netd runs in a root namespace which contains all UIDs.
// - netd runs in a user namespace where the uid mapping is written once before netd starts.
// In that case, an attempt to write more than once to a uid_map file in a user namespace
// fails with EPERM. Netd can therefore assumes the max valid uid to be const.
const uid_t mMaxUid;
FirewallType mFirewallType;
bool mUseBpfOwnerMatch;
std::set<std::string> mIfaceRules;
int flushRules(void);
int attachChain(const char*, const char*);
int detachChain(const char*, const char*);
int createChain(const char*, FirewallType);
FirewallType getFirewallType(ChildChain);
};
} // namespace net
} // namespace android
#endif
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