NetdClient.cpp revision 31f4210e6fc5c9b749468a2af0bac94992352010 
1/*
2 * Copyright (C) 2014 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 "NetdClient.h"
18
19#include "FwmarkClient.h"
20#include "FwmarkCommand.h"
21#include "resolv_netid.h"
22
23#include <atomic>
24#include <sys/socket.h>
25#include <unistd.h>
26
27namespace {
28
29std::atomic_uint netIdForProcess(NETID_UNSET);
30std::atomic_uint netIdForResolv(NETID_UNSET);
31
32typedef int (*Accept4FunctionType)(int, sockaddr*, socklen_t*, int);
33typedef int (*ConnectFunctionType)(int, const sockaddr*, socklen_t);
34typedef int (*SocketFunctionType)(int, int, int);
35typedef unsigned (*NetIdForResolvFunctionType)(unsigned);
36
37// These variables are only modified at startup (when libc.so is loaded) and never afterwards, so
38// it's okay that they are read later at runtime without a lock.
39Accept4FunctionType libcAccept4 = 0;
40ConnectFunctionType libcConnect = 0;
41SocketFunctionType libcSocket = 0;
42
43int closeFdAndSetErrno(int fd, int error) {
44    close(fd);
45    errno = error;
46    return -1;
47}
48
49int netdClientAccept4(int sockfd, sockaddr* addr, socklen_t* addrlen, int flags) {
50    int acceptedSocket = libcAccept4(sockfd, addr, addrlen, flags);
51    if (acceptedSocket == -1) {
52        return -1;
53    }
54    int family;
55    if (addr) {
56        family = addr->sa_family;
57    } else {
58        socklen_t familyLen = sizeof(family);
59        if (getsockopt(acceptedSocket, SOL_SOCKET, SO_DOMAIN, &family, &familyLen) == -1) {
60            return closeFdAndSetErrno(acceptedSocket, errno);
61        }
62    }
63    if (FwmarkClient::shouldSetFwmark(family)) {
64        FwmarkCommand command = {FwmarkCommand::ON_ACCEPT, 0};
65        int error = FwmarkClient().send(&command, sizeof(command), acceptedSocket);
66        if (error) {
67            return closeFdAndSetErrno(acceptedSocket, error);
68        }
69    }
70    return acceptedSocket;
71}
72
73int netdClientConnect(int sockfd, const sockaddr* addr, socklen_t addrlen) {
74    if (sockfd >= 0 && addr && FwmarkClient::shouldSetFwmark(addr->sa_family)) {
75        FwmarkCommand command = {FwmarkCommand::ON_CONNECT, 0};
76        int error = FwmarkClient().send(&command, sizeof(command), sockfd);
77        if (error) {
78            errno = error;
79            return -1;
80        }
81    }
82    return libcConnect(sockfd, addr, addrlen);
83}
84
85int netdClientSocket(int domain, int type, int protocol) {
86    int socketFd = libcSocket(domain, type, protocol);
87    if (socketFd == -1) {
88        return -1;
89    }
90    unsigned netId = netIdForProcess;
91    if (netId != NETID_UNSET && FwmarkClient::shouldSetFwmark(domain)) {
92        int error = setNetworkForSocket(netId, socketFd);
93        if (error) {
94            return closeFdAndSetErrno(socketFd, error);
95        }
96    }
97    return socketFd;
98}
99
100unsigned getNetworkForResolv(unsigned netId) {
101    if (netId != NETID_UNSET) {
102        return netId;
103    }
104    netId = netIdForProcess;
105    if (netId != NETID_UNSET) {
106        return netId;
107    }
108    return netIdForResolv;
109}
110
111int setNetworkForTarget(unsigned netId, std::atomic_uint* target) {
112    if (netId == NETID_UNSET) {
113        *target = netId;
114        return 0;
115    }
116    // Verify that we are allowed to use |netId|, by creating a socket and trying to have it marked
117    // with the netId. Call libcSocket() directly; else the socket creation (via netdClientSocket())
118    // might itself cause another check with the fwmark server, which would be wasteful.
119    int socketFd;
120    if (libcSocket) {
121        socketFd = libcSocket(AF_INET6, SOCK_DGRAM, 0);
122    } else {
123        socketFd = socket(AF_INET6, SOCK_DGRAM, 0);
124    }
125    if (socketFd < 0) {
126        return errno;
127    }
128    int error = setNetworkForSocket(netId, socketFd);
129    if (!error) {
130        *target = netId;
131    }
132    close(socketFd);
133    return error;
134}
135
136}  // namespace
137
138// accept() just calls accept4(..., 0), so there's no need to handle accept() separately.
139extern "C" void netdClientInitAccept4(Accept4FunctionType* function) {
140    if (function && *function) {
141        libcAccept4 = *function;
142        *function = netdClientAccept4;
143    }
144}
145
146extern "C" void netdClientInitConnect(ConnectFunctionType* function) {
147    if (function && *function) {
148        libcConnect = *function;
149        *function = netdClientConnect;
150    }
151}
152
153extern "C" void netdClientInitSocket(SocketFunctionType* function) {
154    if (function && *function) {
155        libcSocket = *function;
156        *function = netdClientSocket;
157    }
158}
159
160extern "C" void netdClientInitNetIdForResolv(NetIdForResolvFunctionType* function) {
161    if (function) {
162        *function = getNetworkForResolv;
163    }
164}
165
166extern "C" unsigned getNetworkForProcess() {
167    return netIdForProcess;
168}
169
170extern "C" int setNetworkForSocket(unsigned netId, int socketFd) {
171    if (socketFd < 0) {
172        return EBADF;
173    }
174    FwmarkCommand command = {FwmarkCommand::SELECT_NETWORK, netId};
175    return FwmarkClient().send(&command, sizeof(command), socketFd);
176}
177
178extern "C" int setNetworkForProcess(unsigned netId) {
179    return setNetworkForTarget(netId, &netIdForProcess);
180}
181
182extern "C" int setNetworkForResolv(unsigned netId) {
183    return setNetworkForTarget(netId, &netIdForResolv);
184}
185
186extern "C" int protectFromVpn(int socketFd) {
187    if (socketFd < 0) {
188        return EBADF;
189    }
190    FwmarkCommand command = {FwmarkCommand::PROTECT_FROM_VPN, 0};
191    return FwmarkClient().send(&command, sizeof(command), socketFd);
192}
193