/*
* Copyright (C) 2016 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.
*/
#include <regex>
#include <set>
#include <string>
#include <android-base/strings.h>
#include <android-base/stringprintf.h>
#define LOG_TAG "Netd"
#include <cutils/log.h>
#include "Controllers.h"
#include "IdletimerController.h"
#include "NetworkController.h"
#include "RouteController.h"
#include "Stopwatch.h"
#include "oem_iptables_hook.h"
#include "XfrmController.h"
namespace android {
namespace net {
using android::base::Join;
using android::base::StringPrintf;
using android::base::StringAppendF;
auto Controllers::execIptablesRestore = ::execIptablesRestore;
auto Controllers::execIptablesRestoreWithOutput = ::execIptablesRestoreWithOutput;
namespace {
/**
* List of module chains to be created, along with explicit ordering. ORDERING
* IS CRITICAL, AND SHOULD BE TRIPLE-CHECKED WITH EACH CHANGE.
*/
static const std::vector<const char*> FILTER_INPUT = {
// Bandwidth should always be early in input chain, to make sure we
// correctly count incoming traffic against data plan.
BandwidthController::LOCAL_INPUT,
FirewallController::LOCAL_INPUT,
};
static const std::vector<const char*> FILTER_FORWARD = {
OEM_IPTABLES_FILTER_FORWARD,
FirewallController::LOCAL_FORWARD,
BandwidthController::LOCAL_FORWARD,
TetherController::LOCAL_FORWARD,
};
static const std::vector<const char*> FILTER_OUTPUT = {
OEM_IPTABLES_FILTER_OUTPUT,
FirewallController::LOCAL_OUTPUT,
StrictController::LOCAL_OUTPUT,
BandwidthController::LOCAL_OUTPUT,
};
static const std::vector<const char*> RAW_PREROUTING = {
BandwidthController::LOCAL_RAW_PREROUTING,
IdletimerController::LOCAL_RAW_PREROUTING,
TetherController::LOCAL_RAW_PREROUTING,
};
static const std::vector<const char*> MANGLE_POSTROUTING = {
OEM_IPTABLES_MANGLE_POSTROUTING,
BandwidthController::LOCAL_MANGLE_POSTROUTING,
IdletimerController::LOCAL_MANGLE_POSTROUTING,
};
static const std::vector<const char*> MANGLE_INPUT = {
WakeupController::LOCAL_MANGLE_INPUT,
RouteController::LOCAL_MANGLE_INPUT,
};
static const std::vector<const char*> MANGLE_FORWARD = {
TetherController::LOCAL_MANGLE_FORWARD,
};
static const std::vector<const char*> NAT_PREROUTING = {
OEM_IPTABLES_NAT_PREROUTING,
};
static const std::vector<const char*> NAT_POSTROUTING = {
TetherController::LOCAL_NAT_POSTROUTING,
};
// Commands to create child chains and to match created chains in iptables -S output. Keep in sync.
static const char* CHILD_CHAIN_TEMPLATE = "-A %s -j %s\n";
static const std::regex CHILD_CHAIN_REGEX("^-A ([^ ]+) -j ([^ ]+)$",
std::regex_constants::extended);
} // namespace
/* static */
std::set<std::string> Controllers::findExistingChildChains(const IptablesTarget target,
const char* table,
const char* parentChain) {
if (target == V4V6) {
ALOGE("findExistingChildChains only supports one protocol at a time");
abort();
}
std::set<std::string> existing;
// List the current contents of parentChain.
//
// TODO: there is no guarantee that nothing else modifies the chain in the few milliseconds
// between when we list the existing rules and when we delete them. However:
// - Since this code is only run on startup, nothing else in netd will be running.
// - While vendor code is known to add its own rules to chains created by netd, it should never
// be modifying the rules in childChains or the rules that hook said chains into their parent
// chains.
std::string command = StringPrintf("*%s\n-S %s\nCOMMIT\n", table, parentChain);
std::string output;
if (Controllers::execIptablesRestoreWithOutput(target, command, &output) == -1) {
ALOGE("Error listing chain %s in table %s\n", parentChain, table);
return existing;
}
// The only rules added by createChildChains are of the simple form "-A <parent> -j <child>".
// Find those rules and add each one's child chain to existing.
std::smatch matches;
std::stringstream stream(output);
std::string rule;
while (std::getline(stream, rule, '\n')) {
if (std::regex_search(rule, matches, CHILD_CHAIN_REGEX) && matches[1] == parentChain) {
existing.insert(matches[2]);
}
}
return existing;
}
/* static */
void Controllers::createChildChains(IptablesTarget target, const char* table,
const char* parentChain,
const std::vector<const char*>& childChains,
bool exclusive) {
std::string command = StringPrintf("*%s\n", table);
// We cannot just clear all the chains we create because vendor code modifies filter OUTPUT and
// mangle POSTROUTING directly. So:
//
// - If we're the exclusive owner of this chain, simply clear it entirely.
// - If not, then list the chain's current contents to ensure that if we restart after a crash,
// we leave the existing rules alone in the positions they currently occupy. This is faster
// than blindly deleting our rules and recreating them, because deleting a rule that doesn't
// exists causes iptables-restore to quit, which takes ~30ms per delete. It's also more
// correct, because if we delete rules and re-add them, they'll be in the wrong position with
// regards to the vendor rules.
//
// TODO: Make all chains exclusive once vendor code uses the oem_* rules.
std::set<std::string> existingChildChains;
if (exclusive) {
// Just running ":chain -" flushes user-defined chains, but not built-in chains like INPUT.
// Since at this point we don't know if parentChain is a built-in chain, do both.
StringAppendF(&command, ":%s -\n", parentChain);
StringAppendF(&command, "-F %s\n", parentChain);
} else {
existingChildChains = findExistingChildChains(target, table, parentChain);
}
for (const auto& childChain : childChains) {
// Always clear the child chain.
StringAppendF(&command, ":%s -\n", childChain);
// But only add it to the parent chain if it's not already there.
if (existingChildChains.find(childChain) == existingChildChains.end()) {
StringAppendF(&command, CHILD_CHAIN_TEMPLATE, parentChain, childChain);
}
}
command += "COMMIT\n";
execIptablesRestore(target, command);
}
Controllers::Controllers()
: clatdCtrl(&netCtrl),
wakeupCtrl(
[this](const WakeupController::ReportArgs& args) {
const auto listener = eventReporter.getNetdEventListener();
if (listener == nullptr) {
ALOGE("getNetdEventListener() returned nullptr. dropping wakeup event");
return;
}
String16 prefix = String16(args.prefix.c_str());
String16 srcIp = String16(args.srcIp.c_str());
String16 dstIp = String16(args.dstIp.c_str());
listener->onWakeupEvent(prefix, args.uid, args.ethertype, args.ipNextHeader,
args.dstHw, srcIp, dstIp, args.srcPort, args.dstPort,
args.timestampNs);
},
&iptablesRestoreCtrl) {
InterfaceController::initializeAll();
}
void Controllers::initChildChains() {
/*
* This is the only time we touch top-level chains in iptables; controllers
* should only mutate rules inside of their children chains, as created by
* the constants above.
*
* Modules should never ACCEPT packets (except in well-justified cases);
* they should instead defer to any remaining modules using RETURN, or
* otherwise DROP/REJECT.
*/
// Create chains for child modules.
createChildChains(V4V6, "filter", "INPUT", FILTER_INPUT, true);
createChildChains(V4V6, "filter", "FORWARD", FILTER_FORWARD, true);
createChildChains(V4V6, "raw", "PREROUTING", RAW_PREROUTING, true);
createChildChains(V4V6, "mangle", "FORWARD", MANGLE_FORWARD, true);
createChildChains(V4V6, "mangle", "INPUT", MANGLE_INPUT, true);
createChildChains(V4, "nat", "PREROUTING", NAT_PREROUTING, true);
createChildChains(V4, "nat", "POSTROUTING", NAT_POSTROUTING, true);
createChildChains(V4, "filter", "OUTPUT", FILTER_OUTPUT, false);
createChildChains(V6, "filter", "OUTPUT", FILTER_OUTPUT, false);
createChildChains(V4, "mangle", "POSTROUTING", MANGLE_POSTROUTING, false);
createChildChains(V6, "mangle", "POSTROUTING", MANGLE_POSTROUTING, false);
}
void Controllers::initIptablesRules() {
Stopwatch s;
initChildChains();
ALOGI("Creating child chains: %.1fms", s.getTimeAndReset());
// Let each module setup their child chains
setupOemIptablesHook();
ALOGI("Setting up OEM hooks: %.1fms", s.getTimeAndReset());
/* When enabled, DROPs all packets except those matching rules. */
firewallCtrl.setupIptablesHooks();
ALOGI("Setting up FirewallController hooks: %.1fms", s.getTimeAndReset());
/* Does DROPs in FORWARD by default */
tetherCtrl.setupIptablesHooks();
ALOGI("Setting up TetherController hooks: %.1fms", s.getTimeAndReset());
/*
* Does REJECT in INPUT, OUTPUT. Does counting also.
* No DROP/REJECT allowed later in netfilter-flow hook order.
*/
bandwidthCtrl.setupIptablesHooks();
ALOGI("Setting up BandwidthController hooks: %.1fms", s.getTimeAndReset());
/*
* Counts in nat: PREROUTING, POSTROUTING.
* No DROP/REJECT allowed later in netfilter-flow hook order.
*/
idletimerCtrl.setupIptablesHooks();
ALOGI("Setting up IdletimerController hooks: %.1fms", s.getTimeAndReset());
}
void Controllers::init() {
initIptablesRules();
Stopwatch s;
netdutils::Status tcStatus = trafficCtrl.start();
if (!isOk(tcStatus)) {
ALOGE("failed to start trafficcontroller: (%s)", toString(tcStatus).c_str());
}
ALOGI("initializing traffic control: %.1fms", s.getTimeAndReset());
bandwidthCtrl.enableBandwidthControl(false);
ALOGI("Disabling bandwidth control: %.1fms", s.getTimeAndReset());
if (int ret = RouteController::Init(NetworkController::LOCAL_NET_ID)) {
ALOGE("failed to initialize RouteController (%s)", strerror(-ret));
}
ALOGI("Initializing RouteController: %.1fms", s.getTimeAndReset());
netdutils::Status xStatus = XfrmController::Init();
if (!isOk(xStatus)) {
ALOGE("Failed to initialize XfrmController (%s)", netdutils::toString(xStatus).c_str());
};
ALOGI("Initializing XfrmController: %.1fms", s.getTimeAndReset());
}
Controllers* gCtls = nullptr;
} // namespace net
} // namespace android