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 "FwmarkClient.h"
18 
19 #include "FwmarkCommand.h"
20 
21 #include <errno.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <sys/socket.h>
25 #include <sys/un.h>
26 #include <unistd.h>
27 
28 namespace {
29 
30 const sockaddr_un FWMARK_SERVER_PATH = {AF_UNIX, "/dev/socket/fwmarkd"};
31 
32 }  // namespace
33 
shouldSetFwmark(int family)34 bool FwmarkClient::shouldSetFwmark(int family) {
35     return (family == AF_INET || family == AF_INET6) && !getenv("ANDROID_NO_USE_FWMARK_CLIENT");
36 }
37 
FwmarkClient()38 FwmarkClient::FwmarkClient() : mChannel(-1) {
39 }
40 
~FwmarkClient()41 FwmarkClient::~FwmarkClient() {
42     if (mChannel >= 0) {
43         close(mChannel);
44     }
45 }
46 
send(FwmarkCommand * data,int fd)47 int FwmarkClient::send(FwmarkCommand* data, int fd) {
48     mChannel = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
49     if (mChannel == -1) {
50         return -errno;
51     }
52 
53     if (TEMP_FAILURE_RETRY(connect(mChannel, reinterpret_cast<const sockaddr*>(&FWMARK_SERVER_PATH),
54                                    sizeof(FWMARK_SERVER_PATH))) == -1) {
55         // If we are unable to connect to the fwmark server, assume there's no error. This protects
56         // against future changes if the fwmark server goes away.
57         return 0;
58     }
59 
60     iovec iov;
61     iov.iov_base = data;
62     iov.iov_len = sizeof(*data);
63 
64     msghdr message;
65     memset(&message, 0, sizeof(message));
66     message.msg_iov = &iov;
67     message.msg_iovlen = 1;
68 
69     union {
70         cmsghdr cmh;
71         char cmsg[CMSG_SPACE(sizeof(fd))];
72     } cmsgu;
73 
74     if (data->cmdId != FwmarkCommand::QUERY_USER_ACCESS) {
75         memset(cmsgu.cmsg, 0, sizeof(cmsgu.cmsg));
76         message.msg_control = cmsgu.cmsg;
77         message.msg_controllen = sizeof(cmsgu.cmsg);
78 
79         cmsghdr* const cmsgh = CMSG_FIRSTHDR(&message);
80         cmsgh->cmsg_len = CMSG_LEN(sizeof(fd));
81         cmsgh->cmsg_level = SOL_SOCKET;
82         cmsgh->cmsg_type = SCM_RIGHTS;
83         memcpy(CMSG_DATA(cmsgh), &fd, sizeof(fd));
84     }
85 
86     if (TEMP_FAILURE_RETRY(sendmsg(mChannel, &message, 0)) == -1) {
87         return -errno;
88     }
89 
90     int error = 0;
91 
92     if (TEMP_FAILURE_RETRY(recv(mChannel, &error, sizeof(error), 0)) == -1) {
93         return -errno;
94     }
95 
96     return error;
97 }
98