1 /*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <regex>
18 #include <string>
19
20 #include <libgen.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <unistd.h>
25
26 #include <android-base/strings.h>
27
28 #define LOG_TAG "NetUtilsWrapper"
29 #include <cutils/log.h>
30
31 #include "NetUtilsWrapper.h"
32
33 #define SYSTEM_DIRNAME "/system/bin/"
34
35 #define OEM_IFACE "[^ ]*oem[0-9]+"
36 #define RMNET_IFACE "(r_)?rmnet_(data)?[0-9]+"
37 #define VENDOR_IFACE "(" OEM_IFACE "|" RMNET_IFACE ")"
38 #define VENDOR_CHAIN "(oem_.*|nm_.*|qcom_.*)"
39
40 // List of net utils wrapped by this program
41 // The list MUST be in descending order of string length
42 const char *netcmds[] = {
43 "ip6tables",
44 "iptables",
45 "ndc",
46 "tc",
47 "ip",
48 NULL,
49 };
50
51 // List of regular expressions of expected commands.
52 const char *EXPECTED_REGEXPS[] = {
53 #define CMD "^" SYSTEM_DIRNAME
54 // Create, delete, and manage OEM networks.
55 CMD "ndc network (create|destroy) oem[0-9]+( |$)",
56 CMD "ndc network interface (add|remove) oem[0-9]+ " VENDOR_IFACE,
57 CMD "ndc network route (add|remove) oem[0-9]+ ",
58 CMD "ndc ipfwd (enable|disable) ",
59 CMD "ndc ipfwd (add|remove) .*" VENDOR_IFACE,
60
61 // Manage vendor iptables rules.
62 CMD "ip(6)?tables -w.* (-A|-D|-F|-I|-N|-X) " VENDOR_CHAIN,
63 CMD "ip(6)?tables -w.* (-i|-o) " VENDOR_IFACE,
64
65 // Manage IPsec state.
66 CMD "ip xfrm .*",
67
68 // Manage vendor interfaces.
69 CMD "tc .* dev " VENDOR_IFACE,
70 CMD "ip( -4| -6)? (addr|address) (add|del|delete|flush).* dev " VENDOR_IFACE,
71
72 // Other activities observed on current devices. In future releases, these should be supported
73 // in a way that is less likely to interfere with general Android networking behaviour.
74 CMD "tc qdisc del dev root",
75 CMD "ip( -4| -6)? rule .* goto 13000 prio 11999",
76 CMD "ip( -4| -6)? rule .* prio 25000",
77 CMD "ip(6)?tables -w .* -j " VENDOR_CHAIN,
78 CMD "iptables -w -t mangle -[AD] PREROUTING -m socket --nowildcard --restore-skmark -j ACCEPT",
79 CMD "ndc network interface (add|remove) oem[0-9]+$", // Invalid command: no interface removed.
80 #undef CMD
81 };
82
checkExpectedCommand(int argc,char ** argv)83 bool checkExpectedCommand(int argc, char **argv) {
84 static bool loggedError = false;
85 std::vector<const char*> allArgs(argc);
86 for (int i = 0; i < argc; i++) {
87 allArgs[i] = argv[i];
88 }
89 std::string fullCmd = android::base::Join(allArgs, ' ');
90 for (size_t i = 0; i < ARRAY_SIZE(EXPECTED_REGEXPS); i++) {
91 const std::regex expectedRegexp(EXPECTED_REGEXPS[i], std::regex_constants::extended);
92 if (std::regex_search(fullCmd, expectedRegexp)) {
93 return true;
94 }
95 }
96 if (!loggedError) {
97 ALOGI("Unexpected command: %s", fullCmd.c_str());
98 fprintf(stderr, LOG_TAG ": Unexpected command: %s\n", fullCmd.c_str());
99 loggedError = true;
100 }
101 return false;
102 }
103
104
105 // This is the only gateway for vendor programs to reach net utils.
doMain(int argc,char ** argv)106 int doMain(int argc, char **argv) {
107 char *progname = argv[0];
108 char *basename = NULL;
109
110 basename = strrchr(progname, '/');
111 basename = basename ? basename + 1 : progname;
112
113 for (int i = 0; netcmds[i]; ++i) {
114 size_t len = strlen(netcmds[i]);
115 if (!strncmp(basename, netcmds[i], len)) {
116 // truncate to match netcmds[i]
117 basename[len] = '\0';
118
119 // hardcode the path to /system so it cannot be overwritten
120 char *cmd;
121 if (asprintf(&cmd, "%s%s", SYSTEM_DIRNAME, basename) == -1) {
122 perror("asprintf");
123 exit(EXIT_FAILURE);
124 }
125 argv[0] = cmd;
126 if (checkExpectedCommand(argc, argv)) {
127 execv(cmd, argv);
128 }
129 }
130 }
131
132 // Invalid command. Reject and fail.
133 exit(EXIT_FAILURE);
134 }
135