| /* |
| * Copyright (C) 2008 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. |
| */ |
| |
| #define LOG_NDEBUG 0 |
| |
| #include <stdlib.h> |
| #include <errno.h> |
| #include <sys/socket.h> |
| #include <sys/stat.h> |
| #include <sys/wait.h> |
| #include <fcntl.h> |
| #include <netinet/in.h> |
| #include <arpa/inet.h> |
| #include <string.h> |
| #include <cutils/properties.h> |
| |
| #define LOG_TAG "NatController" |
| #include <android-base/stringprintf.h> |
| #include <cutils/log.h> |
| #include <logwrap/logwrap.h> |
| |
| #include "NetdConstants.h" |
| #include "NatController.h" |
| #include "NetdConstants.h" |
| #include "RouteController.h" |
| |
| using android::base::StringPrintf; |
| |
| const char* NatController::LOCAL_FORWARD = "natctrl_FORWARD"; |
| const char* NatController::LOCAL_MANGLE_FORWARD = "natctrl_mangle_FORWARD"; |
| const char* NatController::LOCAL_NAT_POSTROUTING = "natctrl_nat_POSTROUTING"; |
| const char* NatController::LOCAL_RAW_PREROUTING = "natctrl_raw_PREROUTING"; |
| const char* NatController::LOCAL_TETHER_COUNTERS_CHAIN = "natctrl_tether_counters"; |
| |
| auto NatController::execFunction = android_fork_execvp; |
| auto NatController::iptablesRestoreFunction = execIptablesRestore; |
| |
| NatController::NatController() { |
| } |
| |
| NatController::~NatController() { |
| } |
| |
| struct CommandsAndArgs { |
| /* The array size doesn't really matter as the compiler will barf if too many initializers are specified. */ |
| const char *cmd[32]; |
| bool checkRes; |
| }; |
| |
| int NatController::runCmd(int argc, const char **argv) { |
| int res; |
| |
| res = execFunction(argc, (char **)argv, NULL, false, false); |
| |
| #if !LOG_NDEBUG |
| std::string full_cmd = argv[0]; |
| argc--; argv++; |
| /* |
| * HACK: Sometimes runCmd() is called with a ridcously large value (32) |
| * and it works because the argv[] contains a NULL after the last |
| * true argv. So here we use the NULL argv[] to terminate when the argc |
| * is horribly wrong, and argc for the normal cases. |
| */ |
| for (; argc && argv[0]; argc--, argv++) { |
| full_cmd += " "; |
| full_cmd += argv[0]; |
| } |
| ALOGV("runCmd(%s) res=%d", full_cmd.c_str(), res); |
| #endif |
| return res; |
| } |
| |
| int NatController::setupIptablesHooks() { |
| int res; |
| res = setDefaults(); |
| if (res < 0) { |
| return res; |
| } |
| |
| // Used to limit downstream mss to the upstream pmtu so we don't end up fragmenting every large |
| // packet tethered devices send. This is IPv4-only, because in IPv6 we send the MTU in the RA. |
| // This is no longer optional and tethering will fail to start if it fails. |
| std::string mssRewriteCommand = StringPrintf( |
| "*mangle\n" |
| "-A %s -p tcp --tcp-flags SYN SYN -j TCPMSS --clamp-mss-to-pmtu\n" |
| "COMMIT\n", LOCAL_MANGLE_FORWARD); |
| |
| // This is for tethering counters. This chain is reached via --goto, and then RETURNS. |
| std::string defaultCommands = StringPrintf( |
| "*filter\n" |
| ":%s -\n" |
| "COMMIT\n", LOCAL_TETHER_COUNTERS_CHAIN); |
| |
| res = iptablesRestoreFunction(V4, mssRewriteCommand); |
| if (res < 0) { |
| return res; |
| } |
| |
| res = iptablesRestoreFunction(V4V6, defaultCommands); |
| if (res < 0) { |
| return res; |
| } |
| |
| ifacePairList.clear(); |
| |
| return 0; |
| } |
| |
| int NatController::setDefaults() { |
| std::string v4Cmd = StringPrintf( |
| "*filter\n" |
| ":%s -\n" |
| "-A %s -j DROP\n" |
| "COMMIT\n" |
| "*nat\n" |
| ":%s -\n" |
| "COMMIT\n", LOCAL_FORWARD, LOCAL_FORWARD, LOCAL_NAT_POSTROUTING); |
| |
| std::string v6Cmd = StringPrintf( |
| "*filter\n" |
| ":%s -\n" |
| "COMMIT\n" |
| "*raw\n" |
| ":%s -\n" |
| "COMMIT\n", LOCAL_FORWARD, LOCAL_RAW_PREROUTING); |
| |
| int res = iptablesRestoreFunction(V4, v4Cmd); |
| if (res < 0) { |
| return res; |
| } |
| |
| res = iptablesRestoreFunction(V6, v6Cmd); |
| if (res < 0) { |
| return res; |
| } |
| |
| natCount = 0; |
| |
| return 0; |
| } |
| |
| int NatController::enableNat(const char* intIface, const char* extIface) { |
| ALOGV("enableNat(intIface=<%s>, extIface=<%s>)",intIface, extIface); |
| |
| if (!isIfaceName(intIface) || !isIfaceName(extIface)) { |
| errno = ENODEV; |
| return -1; |
| } |
| |
| /* Bug: b/9565268. "enableNat wlan0 wlan0". For now we fail until java-land is fixed */ |
| if (!strcmp(intIface, extIface)) { |
| ALOGE("Duplicate interface specified: %s %s", intIface, extIface); |
| errno = EINVAL; |
| return -1; |
| } |
| |
| // add this if we are the first added nat |
| if (natCount == 0) { |
| const char *v4Cmd[] = { |
| IPTABLES_PATH, |
| "-w", |
| "-t", |
| "nat", |
| "-A", |
| LOCAL_NAT_POSTROUTING, |
| "-o", |
| extIface, |
| "-j", |
| "MASQUERADE" |
| }; |
| |
| /* |
| * IPv6 tethering doesn't need the state-based conntrack rules, so |
| * it unconditionally jumps to the tether counters chain all the time. |
| */ |
| const char *v6Cmd[] = {IP6TABLES_PATH, "-w", "-A", LOCAL_FORWARD, |
| "-g", LOCAL_TETHER_COUNTERS_CHAIN}; |
| |
| if (runCmd(ARRAY_SIZE(v4Cmd), v4Cmd) || runCmd(ARRAY_SIZE(v6Cmd), v6Cmd)) { |
| ALOGE("Error setting postroute rule: iface=%s", extIface); |
| // unwind what's been done, but don't care about success - what more could we do? |
| setDefaults(); |
| return -1; |
| } |
| } |
| |
| if (setForwardRules(true, intIface, extIface) != 0) { |
| ALOGE("Error setting forward rules"); |
| if (natCount == 0) { |
| setDefaults(); |
| } |
| errno = ENODEV; |
| return -1; |
| } |
| |
| /* Always make sure the drop rule is at the end */ |
| const char *cmd1[] = { |
| IPTABLES_PATH, |
| "-w", |
| "-D", |
| LOCAL_FORWARD, |
| "-j", |
| "DROP" |
| }; |
| runCmd(ARRAY_SIZE(cmd1), cmd1); |
| const char *cmd2[] = { |
| IPTABLES_PATH, |
| "-w", |
| "-A", |
| LOCAL_FORWARD, |
| "-j", |
| "DROP" |
| }; |
| runCmd(ARRAY_SIZE(cmd2), cmd2); |
| |
| natCount++; |
| return 0; |
| } |
| |
| bool NatController::checkTetherCountingRuleExist(const char *pair_name) { |
| std::list<std::string>::iterator it; |
| |
| for (it = ifacePairList.begin(); it != ifacePairList.end(); it++) { |
| if (*it == pair_name) { |
| /* We already have this counter */ |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| int NatController::setTetherCountingRules(bool add, const char *intIface, const char *extIface) { |
| |
| /* We only ever add tethering quota rules so that they stick. */ |
| if (!add) { |
| return 0; |
| } |
| char *pair_name; |
| asprintf(&pair_name, "%s_%s", intIface, extIface); |
| |
| if (checkTetherCountingRuleExist(pair_name)) { |
| free(pair_name); |
| return 0; |
| } |
| const char *cmd2b[] = { |
| IPTABLES_PATH, |
| "-w", "-A", LOCAL_TETHER_COUNTERS_CHAIN, "-i", intIface, "-o", extIface, "-j", "RETURN" |
| }; |
| |
| const char *cmd2c[] = { |
| IP6TABLES_PATH, |
| "-w", "-A", LOCAL_TETHER_COUNTERS_CHAIN, "-i", intIface, "-o", extIface, "-j", "RETURN" |
| }; |
| |
| if (runCmd(ARRAY_SIZE(cmd2b), cmd2b) || runCmd(ARRAY_SIZE(cmd2c), cmd2c)) { |
| free(pair_name); |
| return -1; |
| } |
| ifacePairList.push_front(pair_name); |
| free(pair_name); |
| |
| asprintf(&pair_name, "%s_%s", extIface, intIface); |
| if (checkTetherCountingRuleExist(pair_name)) { |
| free(pair_name); |
| return 0; |
| } |
| |
| const char *cmd3b[] = { |
| IPTABLES_PATH, |
| "-w", "-A", LOCAL_TETHER_COUNTERS_CHAIN, "-i", extIface, "-o", intIface, "-j", "RETURN" |
| }; |
| |
| const char *cmd3c[] = { |
| IP6TABLES_PATH, |
| "-w", "-A", LOCAL_TETHER_COUNTERS_CHAIN, "-i", extIface, "-o", intIface, "-j", "RETURN" |
| }; |
| |
| if (runCmd(ARRAY_SIZE(cmd3b), cmd3b) || runCmd(ARRAY_SIZE(cmd3c), cmd3c)) { |
| // unwind what's been done, but don't care about success - what more could we do? |
| free(pair_name); |
| return -1; |
| } |
| ifacePairList.push_front(pair_name); |
| free(pair_name); |
| return 0; |
| } |
| |
| int NatController::setForwardRules(bool add, const char *intIface, const char *extIface) { |
| const char *cmd1[] = { |
| IPTABLES_PATH, |
| "-w", |
| add ? "-A" : "-D", |
| LOCAL_FORWARD, |
| "-i", |
| extIface, |
| "-o", |
| intIface, |
| "-m", |
| "state", |
| "--state", |
| "ESTABLISHED,RELATED", |
| "-g", |
| LOCAL_TETHER_COUNTERS_CHAIN |
| }; |
| int rc = 0; |
| |
| if (runCmd(ARRAY_SIZE(cmd1), cmd1) && add) { |
| return -1; |
| } |
| |
| const char *cmd2[] = { |
| IPTABLES_PATH, |
| "-w", |
| add ? "-A" : "-D", |
| LOCAL_FORWARD, |
| "-i", |
| intIface, |
| "-o", |
| extIface, |
| "-m", |
| "state", |
| "--state", |
| "INVALID", |
| "-j", |
| "DROP" |
| }; |
| |
| const char *cmd3[] = { |
| IPTABLES_PATH, |
| "-w", |
| add ? "-A" : "-D", |
| LOCAL_FORWARD, |
| "-i", |
| intIface, |
| "-o", |
| extIface, |
| "-g", |
| LOCAL_TETHER_COUNTERS_CHAIN |
| }; |
| |
| const char *cmd4[] = { |
| IP6TABLES_PATH, |
| "-w", |
| "-t", |
| "raw", |
| add ? "-A" : "-D", |
| LOCAL_RAW_PREROUTING, |
| "-i", |
| intIface, |
| "-m", |
| "rpfilter", |
| "--invert", |
| "!", |
| "-s", |
| "fe80::/64", |
| "-j", |
| "DROP" |
| }; |
| |
| if (runCmd(ARRAY_SIZE(cmd2), cmd2) && add) { |
| // bail on error, but only if adding |
| rc = -1; |
| goto err_invalid_drop; |
| } |
| |
| if (runCmd(ARRAY_SIZE(cmd3), cmd3) && add) { |
| // unwind what's been done, but don't care about success - what more could we do? |
| rc = -1; |
| goto err_return; |
| } |
| |
| if (runCmd(ARRAY_SIZE(cmd4), cmd4) && add) { |
| rc = -1; |
| goto err_rpfilter; |
| } |
| |
| if (setTetherCountingRules(add, intIface, extIface) && add) { |
| rc = -1; |
| goto err_return; |
| } |
| |
| return 0; |
| |
| err_rpfilter: |
| cmd3[2] = "-D"; |
| runCmd(ARRAY_SIZE(cmd3), cmd3); |
| err_return: |
| cmd2[2] = "-D"; |
| runCmd(ARRAY_SIZE(cmd2), cmd2); |
| err_invalid_drop: |
| cmd1[2] = "-D"; |
| runCmd(ARRAY_SIZE(cmd1), cmd1); |
| return rc; |
| } |
| |
| int NatController::disableNat(const char* intIface, const char* extIface) { |
| if (!isIfaceName(intIface) || !isIfaceName(extIface)) { |
| errno = ENODEV; |
| return -1; |
| } |
| |
| setForwardRules(false, intIface, extIface); |
| if (--natCount <= 0) { |
| // handle decrement to 0 case (do reset to defaults) and erroneous dec below 0 |
| setDefaults(); |
| } |
| return 0; |
| } |