/*
* 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 <cutils/log.h>
#include <logwrap/logwrap.h>
#include "NatController.h"
#include "SecondaryTableController.h"
#include "NetdConstants.h"
const char* NatController::LOCAL_FORWARD = "natctrl_FORWARD";
const char* NatController::LOCAL_NAT_POSTROUTING = "natctrl_nat_POSTROUTING";
const char* NatController::LOCAL_TETHER_COUNTERS_CHAIN = "natctrl_tether_counters";
NatController::NatController(SecondaryTableController *ctrl) {
secondaryTableCtrl = ctrl;
}
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 = android_fork_execvp(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;
}
struct CommandsAndArgs defaultCommands[] = {
/*
* Chain for tethering counters.
* This chain is reached via --goto, and then RETURNS.
*/
{{IPTABLES_PATH, "-F", LOCAL_TETHER_COUNTERS_CHAIN,}, 0},
{{IPTABLES_PATH, "-X", LOCAL_TETHER_COUNTERS_CHAIN,}, 0},
{{IPTABLES_PATH, "-N", LOCAL_TETHER_COUNTERS_CHAIN,}, 1},
};
for (unsigned int cmdNum = 0; cmdNum < ARRAY_SIZE(defaultCommands); cmdNum++) {
if (runCmd(ARRAY_SIZE(defaultCommands[cmdNum].cmd), defaultCommands[cmdNum].cmd) &&
defaultCommands[cmdNum].checkRes) {
return -1;
}
}
return 0;
}
int NatController::setDefaults() {
/*
* The following only works because:
* - the defaultsCommands[].cmd array is padded with NULL, and
* - the 1st argc of runCmd() will just be the max for the CommandsAndArgs[].cmd, and
* - internally it will be memcopied to an array and terminated with a NULL.
*/
struct CommandsAndArgs defaultCommands[] = {
{{IPTABLES_PATH, "-F", LOCAL_FORWARD,}, 1},
{{IPTABLES_PATH, "-A", LOCAL_FORWARD, "-j", "DROP"}, 1},
{{IPTABLES_PATH, "-t", "nat", "-F", LOCAL_NAT_POSTROUTING}, 1},
{{IP_PATH, "rule", "flush"}, 0},
{{IP_PATH, "-6", "rule", "flush"}, 0},
{{IP_PATH, "rule", "add", "from", "all", "lookup", "default", "prio", "32767"}, 0},
{{IP_PATH, "rule", "add", "from", "all", "lookup", "main", "prio", "32766"}, 0},
{{IP_PATH, "-6", "rule", "add", "from", "all", "lookup", "default", "prio", "32767"}, 0},
{{IP_PATH, "-6", "rule", "add", "from", "all", "lookup", "main", "prio", "32766"}, 0},
{{IP_PATH, "route", "flush", "cache"}, 0},
};
for (unsigned int cmdNum = 0; cmdNum < ARRAY_SIZE(defaultCommands); cmdNum++) {
if (runCmd(ARRAY_SIZE(defaultCommands[cmdNum].cmd), defaultCommands[cmdNum].cmd) &&
defaultCommands[cmdNum].checkRes) {
return -1;
}
}
natCount = 0;
return 0;
}
bool NatController::checkInterface(const char *iface) {
if (strlen(iface) > IFNAMSIZ) return false;
return true;
}
int NatController::routesOp(bool add, const char *intIface, const char *extIface, char **argv, int addrCount) {
int tableNumber = secondaryTableCtrl->findTableNumber(extIface);
int ret = 0;
if (tableNumber != -1) {
for (int i = 0; i < addrCount; i++) {
if (add) {
ret |= secondaryTableCtrl->modifyFromRule(tableNumber, ADD, argv[5+i]);
ret |= secondaryTableCtrl->modifyLocalRoute(tableNumber, ADD, intIface, argv[5+i]);
} else {
ret |= secondaryTableCtrl->modifyLocalRoute(tableNumber, DEL, intIface, argv[5+i]);
ret |= secondaryTableCtrl->modifyFromRule(tableNumber, DEL, argv[5+i]);
}
}
const char *cmd[] = {
IP_PATH,
"route",
"flush",
"cache"
};
runCmd(ARRAY_SIZE(cmd), cmd);
}
return ret;
}
// 0 1 2 3 4 5
// nat enable intface extface addrcnt nated-ipaddr/prelength
int NatController::enableNat(const int argc, char **argv) {
int i;
int addrCount = atoi(argv[4]);
const char *intIface = argv[2];
const char *extIface = argv[3];
int tableNumber;
ALOGV("enableNat(intIface=<%s>, extIface=<%s>)",intIface, extIface);
if (!checkInterface(intIface) || !checkInterface(extIface)) {
ALOGE("Invalid interface specified");
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;
}
if (argc < 5 + addrCount) {
ALOGE("Missing Argument");
errno = EINVAL;
return -1;
}
if (routesOp(true, intIface, extIface, argv, addrCount)) {
ALOGE("Error setting route rules");
routesOp(false, intIface, extIface, argv, addrCount);
errno = ENODEV;
return -1;
}
// add this if we are the first added nat
if (natCount == 0) {
const char *cmd[] = {
IPTABLES_PATH,
"-t",
"nat",
"-A",
LOCAL_NAT_POSTROUTING,
"-o",
extIface,
"-j",
"MASQUERADE"
};
if (runCmd(ARRAY_SIZE(cmd), cmd)) {
ALOGE("Error seting postroute rule: iface=%s", extIface);
// unwind what's been done, but don't care about success - what more could we do?
routesOp(false, intIface, extIface, argv, addrCount);
setDefaults();
return -1;
}
}
if (setForwardRules(true, intIface, extIface) != 0) {
ALOGE("Error setting forward rules");
routesOp(false, intIface, extIface, argv, addrCount);
if (natCount == 0) {
setDefaults();
}
errno = ENODEV;
return -1;
}
/* Always make sure the drop rule is at the end */
const char *cmd1[] = {
IPTABLES_PATH,
"-D",
LOCAL_FORWARD,
"-j",
"DROP"
};
runCmd(ARRAY_SIZE(cmd1), cmd1);
const char *cmd2[] = {
IPTABLES_PATH,
"-A",
LOCAL_FORWARD,
"-j",
"DROP"
};
runCmd(ARRAY_SIZE(cmd2), cmd2);
natCount++;
return 0;
}
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 *quota_name, *proc_path;
int quota_fd;
asprintf("a_name, "%s_%s", intIface, extIface);
asprintf(&proc_path, "/proc/net/xt_quota/%s", quota_name);
quota_fd = open(proc_path, O_RDONLY);
if (quota_fd >= 0) {
/* quota for iface pair already exists */
free(proc_path);
free(quota_name);
return 0;
}
close(quota_fd);
free(proc_path);
const char *cmd2b[] = {
IPTABLES_PATH,
"-A",
LOCAL_TETHER_COUNTERS_CHAIN,
"-i",
intIface,
"-o",
extIface,
"-m",
"quota2",
"--name",
quota_name,
"--grow",
"-j",
"RETURN"
};
if (runCmd(ARRAY_SIZE(cmd2b), cmd2b) && add) {
free(quota_name);
return -1;
}
free(quota_name);
asprintf("a_name, "%s_%s", extIface, intIface);
asprintf(&proc_path, "/proc/net/xt_quota/%s", quota_name);
quota_fd = open(proc_path, O_RDONLY);
if (quota_fd >= 0) {
/* quota for iface pair already exists */
free(proc_path);
free(quota_name);
return 0;
}
close(quota_fd);
free(proc_path);
const char *cmd3b[] = {
IPTABLES_PATH,
"-A",
LOCAL_TETHER_COUNTERS_CHAIN,
"-i",
extIface,
"-o",
intIface,
"-m",
"quota2",
"--name",
quota_name,
"--grow",
"-j",
"RETURN"
};
if (runCmd(ARRAY_SIZE(cmd3b), cmd3b) && add) {
// unwind what's been done, but don't care about success - what more could we do?
free(quota_name);
return -1;
}
free(quota_name);
return 0;
}
int NatController::setForwardRules(bool add, const char *intIface, const char *extIface) {
const char *cmd1[] = {
IPTABLES_PATH,
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,
add ? "-A" : "-D",
LOCAL_FORWARD,
"-i",
intIface,
"-o",
extIface,
"-m",
"state",
"--state",
"INVALID",
"-j",
"DROP"
};
const char *cmd3[] = {
IPTABLES_PATH,
add ? "-A" : "-D",
LOCAL_FORWARD,
"-i",
intIface,
"-o",
extIface,
"-g",
LOCAL_TETHER_COUNTERS_CHAIN
};
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 (setTetherCountingRules(add, intIface, extIface) && add) {
rc = -1;
goto err_return;
}
return 0;
err_return:
cmd2[1] = "-D";
runCmd(ARRAY_SIZE(cmd2), cmd2);
err_invalid_drop:
cmd1[1] = "-D";
runCmd(ARRAY_SIZE(cmd1), cmd1);
return rc;
}
// nat disable intface extface
// 0 1 2 3 4 5
// nat enable intface extface addrcnt nated-ipaddr/prelength
int NatController::disableNat(const int argc, char **argv) {
int i;
int addrCount = atoi(argv[4]);
const char *intIface = argv[2];
const char *extIface = argv[3];
int tableNumber;
if (!checkInterface(intIface) || !checkInterface(extIface)) {
ALOGE("Invalid interface specified");
errno = ENODEV;
return -1;
}
if (argc < 5 + addrCount) {
ALOGE("Missing Argument");
errno = EINVAL;
return -1;
}
setForwardRules(false, intIface, extIface);
routesOp(false, intIface, extIface, argv, addrCount);
if (--natCount <= 0) {
// handle decrement to 0 case (do reset to defaults) and erroneous dec below 0
setDefaults();
}
return 0;
}