1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
/*
* Copyright (C) 2022 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.
*/
#include "OS.h"
#include <android-base/file.h>
#include <binder/RpcTransportRaw.h>
#include <log/log.h>
#include <string.h>
using android::base::ErrnoError;
using android::base::Result;
namespace android {
// Linux kernel supports up to 253 (from SCM_MAX_FD) for unix sockets.
constexpr size_t kMaxFdsPerMsg = 253;
Result<void> setNonBlocking(android::base::borrowed_fd fd) {
int flags = TEMP_FAILURE_RETRY(fcntl(fd.get(), F_GETFL));
if (flags == -1) {
return ErrnoError() << "Could not get flags for fd";
}
if (int ret = TEMP_FAILURE_RETRY(fcntl(fd.get(), F_SETFL, flags | O_NONBLOCK)); ret == -1) {
return ErrnoError() << "Could not set non-blocking flag for fd";
}
return {};
}
status_t getRandomBytes(uint8_t* data, size_t size) {
int ret = TEMP_FAILURE_RETRY(open("/dev/urandom", O_RDONLY | O_CLOEXEC | O_NOFOLLOW));
if (ret == -1) {
return -errno;
}
base::unique_fd fd(ret);
if (!base::ReadFully(fd, data, size)) {
return -errno;
}
return OK;
}
status_t dupFileDescriptor(int oldFd, int* newFd) {
int ret = fcntl(oldFd, F_DUPFD_CLOEXEC, 0);
if (ret < 0) {
return -errno;
}
*newFd = ret;
return OK;
}
std::unique_ptr<RpcTransportCtxFactory> makeDefaultRpcTransportCtxFactory() {
return RpcTransportCtxFactoryRaw::make();
}
ssize_t sendMessageOnSocket(
const RpcTransportFd& socket, iovec* iovs, int niovs,
const std::vector<std::variant<base::unique_fd, base::borrowed_fd>>* ancillaryFds) {
if (ancillaryFds != nullptr && !ancillaryFds->empty()) {
if (ancillaryFds->size() > kMaxFdsPerMsg) {
errno = EINVAL;
return -1;
}
// CMSG_DATA is not necessarily aligned, so we copy the FDs into a buffer and then
// use memcpy.
int fds[kMaxFdsPerMsg];
for (size_t i = 0; i < ancillaryFds->size(); i++) {
fds[i] = std::visit([](const auto& fd) { return fd.get(); }, ancillaryFds->at(i));
}
const size_t fdsByteSize = sizeof(int) * ancillaryFds->size();
alignas(struct cmsghdr) char msgControlBuf[CMSG_SPACE(sizeof(int) * kMaxFdsPerMsg)];
msghdr msg{
.msg_iov = iovs,
.msg_iovlen = static_cast<decltype(msg.msg_iovlen)>(niovs),
.msg_control = msgControlBuf,
.msg_controllen = sizeof(msgControlBuf),
};
cmsghdr* cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(fdsByteSize);
memcpy(CMSG_DATA(cmsg), fds, fdsByteSize);
msg.msg_controllen = CMSG_SPACE(fdsByteSize);
return TEMP_FAILURE_RETRY(sendmsg(socket.fd.get(), &msg, MSG_NOSIGNAL | MSG_CMSG_CLOEXEC));
}
msghdr msg{
.msg_iov = iovs,
// posix uses int, glibc uses size_t. niovs is a
// non-negative int and can be cast to either.
.msg_iovlen = static_cast<decltype(msg.msg_iovlen)>(niovs),
};
return TEMP_FAILURE_RETRY(sendmsg(socket.fd.get(), &msg, MSG_NOSIGNAL));
}
ssize_t receiveMessageFromSocket(
const RpcTransportFd& socket, iovec* iovs, int niovs,
std::vector<std::variant<base::unique_fd, base::borrowed_fd>>* ancillaryFds) {
if (ancillaryFds != nullptr) {
int fdBuffer[kMaxFdsPerMsg];
alignas(struct cmsghdr) char msgControlBuf[CMSG_SPACE(sizeof(fdBuffer))];
msghdr msg{
.msg_iov = iovs,
.msg_iovlen = static_cast<decltype(msg.msg_iovlen)>(niovs),
.msg_control = msgControlBuf,
.msg_controllen = sizeof(msgControlBuf),
};
ssize_t processSize = TEMP_FAILURE_RETRY(recvmsg(socket.fd.get(), &msg, MSG_NOSIGNAL));
if (processSize < 0) {
return -1;
}
for (cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); cmsg != nullptr; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
// NOTE: It is tempting to reinterpret_cast, but cmsg(3) explicitly asks
// application devs to memcpy the data to ensure memory alignment.
size_t dataLen = cmsg->cmsg_len - CMSG_LEN(0);
LOG_ALWAYS_FATAL_IF(dataLen > sizeof(fdBuffer)); // validity check
memcpy(fdBuffer, CMSG_DATA(cmsg), dataLen);
size_t fdCount = dataLen / sizeof(int);
ancillaryFds->reserve(ancillaryFds->size() + fdCount);
for (size_t i = 0; i < fdCount; i++) {
ancillaryFds->emplace_back(base::unique_fd(fdBuffer[i]));
}
break;
}
}
if (msg.msg_flags & MSG_CTRUNC) {
errno = EPIPE;
return -1;
}
return processSize;
}
msghdr msg{
.msg_iov = iovs,
// posix uses int, glibc uses size_t. niovs is a
// non-negative int and can be cast to either.
.msg_iovlen = static_cast<decltype(msg.msg_iovlen)>(niovs),
};
return TEMP_FAILURE_RETRY(recvmsg(socket.fd.get(), &msg, MSG_NOSIGNAL));
}
} // namespace android
|
