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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.
*/
#include <set>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cstdint>
#define LOG_TAG "FirewallController"
#define LOG_NDEBUG 0
#include <android-base/file.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <log/log.h>
#include "Controllers.h"
#include "FirewallController.h"
#include "NetdConstants.h"
using android::base::Join;
using android::base::StringAppendF;
using android::base::StringPrintf;
namespace android {
namespace net {
auto FirewallController::execIptablesRestore = ::execIptablesRestore;
const char* FirewallController::TABLE = "filter";
const char* FirewallController::LOCAL_INPUT = "fw_INPUT";
const char* FirewallController::LOCAL_OUTPUT = "fw_OUTPUT";
const char* FirewallController::LOCAL_FORWARD = "fw_FORWARD";
// ICMPv6 types that are required for any form of IPv6 connectivity to work. Note that because the
// fw_dozable chain is called from both INPUT and OUTPUT, this includes both packets that we need
// to be able to send (e.g., RS, NS), and packets that we need to receive (e.g., RA, NA).
const char* FirewallController::ICMPV6_TYPES[] = {
"packet-too-big",
"router-solicitation",
"router-advertisement",
"neighbour-solicitation",
"neighbour-advertisement",
"redirect",
};
FirewallController::FirewallController(void) {
// If no rules are set, it's in DENYLIST mode
mFirewallType = DENYLIST;
mIfaceRules = {};
}
int FirewallController::setupIptablesHooks(void) {
return flushRules();
}
int FirewallController::setFirewallType(FirewallType ftype) {
int res = 0;
if (mFirewallType != ftype) {
// flush any existing rules
resetFirewall();
if (ftype == ALLOWLIST) {
// create default rule to drop all traffic
std::string command =
"*filter\n"
"-A fw_INPUT -j DROP\n"
"-A fw_OUTPUT -j REJECT\n"
"-A fw_FORWARD -j REJECT\n"
"COMMIT\n";
res = execIptablesRestore(V4V6, command.c_str());
}
// Set this after calling disableFirewall(), since it defaults to ALLOWLIST there
mFirewallType = ftype;
}
return res ? -EREMOTEIO : 0;
}
int FirewallController::flushRules() {
std::string command =
"*filter\n"
":fw_INPUT -\n"
":fw_OUTPUT -\n"
":fw_FORWARD -\n"
"-6 -A fw_OUTPUT ! -o lo -s ::1 -j DROP\n"
"COMMIT\n";
return (execIptablesRestore(V4V6, command.c_str()) == 0) ? 0 : -EREMOTEIO;
}
int FirewallController::resetFirewall(void) {
mFirewallType = ALLOWLIST;
mIfaceRules.clear();
return flushRules();
}
int FirewallController::isFirewallEnabled(void) {
// TODO: verify that rules are still in place near top
return -1;
}
int FirewallController::setInterfaceRule(const char* iface, FirewallRule rule) {
if (mFirewallType == DENYLIST) {
// Unsupported in DENYLIST mode
return -EINVAL;
}
if (!isIfaceName(iface)) {
errno = ENOENT;
return -ENOENT;
}
// Only delete rules if we actually added them, because otherwise our iptables-restore
// processes will terminate with "no such rule" errors and cause latency penalties while we
// spin up new ones.
const char* op;
if (rule == ALLOW && mIfaceRules.find(iface) == mIfaceRules.end()) {
op = "-I";
mIfaceRules.insert(iface);
} else if (rule == DENY && mIfaceRules.find(iface) != mIfaceRules.end()) {
op = "-D";
mIfaceRules.erase(iface);
} else {
return 0;
}
std::string command = Join(std::vector<std::string> {
"*filter",
StringPrintf("%s fw_INPUT -i %s -j RETURN", op, iface),
StringPrintf("%s fw_OUTPUT -o %s -j RETURN", op, iface),
"COMMIT\n"
}, "\n");
return (execIptablesRestore(V4V6, command) == 0) ? 0 : -EREMOTEIO;
}
/* static */
std::string FirewallController::makeCriticalCommands(IptablesTarget target, const char* chainName) {
// Allow ICMPv6 packets necessary to make IPv6 connectivity work. http://b/23158230 .
std::string commands;
if (target == V6) {
for (size_t i = 0; i < ARRAY_SIZE(ICMPV6_TYPES); i++) {
StringAppendF(&commands, "-A %s -p icmpv6 --icmpv6-type %s -j RETURN\n",
chainName, ICMPV6_TYPES[i]);
}
}
return commands;
}
} // namespace net
} // namespace android
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