1 /*
2 * Copyright (C) 2016 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 <errno.h>
18 #include <string.h>
19
20 #include "LeakPipe.h"
21
22 #include "log.h"
23
SendFd(int sock,int fd)24 bool LeakPipe::SendFd(int sock, int fd) {
25 struct msghdr hdr{};
26 struct iovec iov{};
27 unsigned int data = 0xfdfdfdfd;
28 alignas(struct cmsghdr) char cmsgbuf[CMSG_SPACE(sizeof(int))];
29
30 hdr.msg_iov = &iov;
31 hdr.msg_iovlen = 1;
32 iov.iov_base = &data;
33 iov.iov_len = sizeof(data);
34
35 hdr.msg_control = cmsgbuf;
36 hdr.msg_controllen = CMSG_LEN(sizeof(int));
37
38 struct cmsghdr* cmsg = CMSG_FIRSTHDR(&hdr);
39 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
40 cmsg->cmsg_level = SOL_SOCKET;
41 cmsg->cmsg_type = SCM_RIGHTS;
42
43 *(int*)CMSG_DATA(cmsg) = fd;
44
45 int ret = sendmsg(sock, &hdr, 0);
46 if (ret < 0) {
47 ALOGE("failed to send fd: %s", strerror(errno));
48 return false;
49 }
50 if (ret == 0) {
51 ALOGE("eof when sending fd");
52 return false;
53 }
54
55 return true;
56 }
57
ReceiveFd(int sock)58 int LeakPipe::ReceiveFd(int sock) {
59 struct msghdr hdr{};
60 struct iovec iov{};
61 unsigned int data;
62 alignas(struct cmsghdr) char cmsgbuf[CMSG_SPACE(sizeof(int))];
63
64 hdr.msg_iov = &iov;
65 hdr.msg_iovlen = 1;
66 iov.iov_base = &data;
67 iov.iov_len = sizeof(data);
68
69 hdr.msg_control = cmsgbuf;
70 hdr.msg_controllen = CMSG_LEN(sizeof(int));
71
72 int ret = recvmsg(sock, &hdr, 0);
73 if (ret < 0) {
74 ALOGE("failed to receive fd: %s", strerror(errno));
75 return -1;
76 }
77 if (ret == 0) {
78 ALOGE("eof when receiving fd");
79 return -1;
80 }
81
82 struct cmsghdr* cmsg = CMSG_FIRSTHDR(&hdr);
83 if (cmsg == NULL || cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
84 ALOGE("missing fd while receiving fd");
85 return -1;
86 }
87
88 return *(int*)CMSG_DATA(cmsg);
89 }
90