| /* |
| * Copyright 2018 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. |
| * |
| * main.c - main function |
| */ |
| |
| #include <errno.h> |
| #include <netinet/in.h> |
| #include <stdint.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <sys/capability.h> |
| #include <unistd.h> |
| |
| #include "resolv_netid.h" |
| |
| #include "clatd.h" |
| #include "common.h" |
| #include "config.h" |
| #include "logging.h" |
| #include "setif.h" |
| #include "tun.h" |
| |
| #define DEVICEPREFIX "v4-" |
| |
| /* function: print_help |
| * in case the user is running this on the command line |
| */ |
| void print_help() { |
| printf("android-clat arguments:\n"); |
| printf("-i [uplink interface]\n"); |
| printf("-p [plat prefix]\n"); |
| printf("-4 [IPv4 address]\n"); |
| printf("-6 [IPv6 address]\n"); |
| printf("-n [NetId]\n"); |
| printf("-m [socket mark]\n"); |
| } |
| |
| /* function: main |
| * allocate and setup the tun device, then run the event loop |
| */ |
| int main(int argc, char **argv) { |
| struct tun_data tunnel; |
| int opt; |
| char *uplink_interface = NULL, *plat_prefix = NULL, *net_id_str = NULL, *mark_str = NULL; |
| char *v4_addr = NULL, *v6_addr = NULL; |
| unsigned net_id = NETID_UNSET; |
| uint32_t mark = MARK_UNSET; |
| unsigned len; |
| |
| while ((opt = getopt(argc, argv, "i:p:4:6:n:m:h")) != -1) { |
| switch (opt) { |
| case 'i': |
| uplink_interface = optarg; |
| break; |
| case 'p': |
| plat_prefix = optarg; |
| break; |
| case '4': |
| v4_addr = optarg; |
| break; |
| case '6': |
| v6_addr = optarg; |
| break; |
| case 'n': |
| net_id_str = optarg; |
| break; |
| case 'm': |
| mark_str = optarg; |
| break; |
| case 'h': |
| print_help(); |
| exit(0); |
| default: |
| logmsg(ANDROID_LOG_FATAL, "Unknown option -%c. Exiting.", (char)optopt); |
| exit(1); |
| } |
| } |
| |
| if (uplink_interface == NULL) { |
| logmsg(ANDROID_LOG_FATAL, "clatd called without an interface"); |
| exit(1); |
| } |
| |
| if (net_id_str != NULL && !parse_unsigned(net_id_str, &net_id)) { |
| logmsg(ANDROID_LOG_FATAL, "invalid NetID %s", net_id_str); |
| exit(1); |
| } |
| |
| if (mark_str != NULL && !parse_unsigned(mark_str, &mark)) { |
| logmsg(ANDROID_LOG_FATAL, "invalid mark %s", mark_str); |
| exit(1); |
| } |
| |
| len = snprintf(tunnel.device4, sizeof(tunnel.device4), "%s%s", DEVICEPREFIX, uplink_interface); |
| if (len >= sizeof(tunnel.device4)) { |
| logmsg(ANDROID_LOG_FATAL, "interface name too long '%s'", tunnel.device4); |
| exit(1); |
| } |
| |
| logmsg(ANDROID_LOG_INFO, "Starting clat version %s on %s netid=%s mark=%s plat=%s v4=%s v6=%s", |
| CLATD_VERSION, uplink_interface, net_id_str ? net_id_str : "(none)", |
| mark_str ? mark_str : "(none)", plat_prefix ? plat_prefix : "(none)", |
| v4_addr ? v4_addr : "(none)", v6_addr ? v6_addr : "(none)"); |
| |
| // run under a regular user but keep needed capabilities |
| drop_root_but_keep_caps(); |
| |
| // open our raw sockets before dropping privs |
| open_sockets(&tunnel, mark); |
| |
| // keeps only admin capability |
| set_capability(1 << CAP_NET_ADMIN); |
| |
| // we can create tun devices as non-root because we're in the VPN group. |
| tunnel.fd4 = tun_open(); |
| if (tunnel.fd4 < 0) { |
| logmsg(ANDROID_LOG_FATAL, "tun_open4 failed: %s", strerror(errno)); |
| exit(1); |
| } |
| |
| // When run from netd, the environment variable ANDROID_DNS_MODE is set to |
| // "local", but that only works for the netd process itself. Removing the |
| // following line causes XLAT failure in permissive mode. |
| unsetenv("ANDROID_DNS_MODE"); |
| |
| configure_interface(uplink_interface, plat_prefix, v4_addr, v6_addr, &tunnel, net_id); |
| |
| // Drop all remaining capabilities. |
| set_capability(0); |
| |
| // Loop until someone sends us a signal or brings down the tun interface. |
| if (signal(SIGTERM, stop_loop) == SIG_ERR) { |
| logmsg(ANDROID_LOG_FATAL, "sigterm handler failed: %s", strerror(errno)); |
| exit(1); |
| } |
| |
| event_loop(&tunnel); |
| |
| logmsg(ANDROID_LOG_INFO, "Shutting down clat on %s", uplink_interface); |
| del_anycast_address(tunnel.write_fd6, &Global_Clatd_Config.ipv6_local_subnet); |
| |
| return 0; |
| } |