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
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
|
/*
* Copyright (C) 2016 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 specic language governing permissions and
* limitations under the License.
*/
#include "libappfuse/FuseBuffer.h"
#include <inttypes.h>
#include <string.h>
#include <unistd.h>
#include <algorithm>
#include <type_traits>
#include <sys/socket.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/macros.h>
namespace android {
namespace fuse {
namespace {
template <typename T>
bool CheckHeaderLength(const FuseMessage<T>* self, const char* name) {
const auto& header = static_cast<const T*>(self)->header;
if (header.len >= sizeof(header) && header.len <= sizeof(T)) {
return true;
} else {
LOG(ERROR) << "Invalid header length is found in " << name << ": " << header.len;
return false;
}
}
template <typename T>
ResultOrAgain ReadInternal(FuseMessage<T>* self, int fd, int sockflag) {
char* const buf = reinterpret_cast<char*>(self);
const ssize_t result = sockflag ? TEMP_FAILURE_RETRY(recv(fd, buf, sizeof(T), sockflag))
: TEMP_FAILURE_RETRY(read(fd, buf, sizeof(T)));
switch (result) {
case 0:
// Expected EOF.
return ResultOrAgain::kFailure;
case -1:
if (errno == EAGAIN) {
return ResultOrAgain::kAgain;
}
PLOG(ERROR) << "Failed to read a FUSE message";
return ResultOrAgain::kFailure;
}
const auto& header = static_cast<const T*>(self)->header;
if (result < static_cast<ssize_t>(sizeof(header))) {
LOG(ERROR) << "Read bytes " << result << " are shorter than header size " << sizeof(header);
return ResultOrAgain::kFailure;
}
if (!CheckHeaderLength<T>(self, "Read")) {
return ResultOrAgain::kFailure;
}
if (static_cast<uint32_t>(result) != header.len) {
LOG(ERROR) << "Read bytes " << result << " are different from header.len " << header.len;
return ResultOrAgain::kFailure;
}
return ResultOrAgain::kSuccess;
}
template <typename T>
ResultOrAgain WriteInternal(const FuseMessage<T>* self, int fd, int sockflag) {
if (!CheckHeaderLength<T>(self, "Write")) {
return ResultOrAgain::kFailure;
}
const char* const buf = reinterpret_cast<const char*>(self);
const auto& header = static_cast<const T*>(self)->header;
const int result = sockflag ? TEMP_FAILURE_RETRY(send(fd, buf, header.len, sockflag))
: TEMP_FAILURE_RETRY(write(fd, buf, header.len));
if (result == -1) {
if (errno == EAGAIN) {
return ResultOrAgain::kAgain;
}
PLOG(ERROR) << "Failed to write a FUSE message";
return ResultOrAgain::kFailure;
}
CHECK(static_cast<uint32_t>(result) == header.len);
return ResultOrAgain::kSuccess;
}
}
static_assert(std::is_standard_layout<FuseBuffer>::value,
"FuseBuffer must be standard layout union.");
bool SetupMessageSockets(base::unique_fd (*result)[2]) {
base::unique_fd fds[2];
{
int raw_fds[2];
if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, raw_fds) == -1) {
PLOG(ERROR) << "Failed to create sockets for proxy";
return false;
}
fds[0].reset(raw_fds[0]);
fds[1].reset(raw_fds[1]);
}
constexpr int kMaxMessageSize = sizeof(FuseBuffer);
if (setsockopt(fds[0], SOL_SOCKET, SO_SNDBUF, &kMaxMessageSize, sizeof(int)) != 0 ||
setsockopt(fds[1], SOL_SOCKET, SO_SNDBUF, &kMaxMessageSize, sizeof(int)) != 0) {
PLOG(ERROR) << "Failed to update buffer size for socket";
return false;
}
(*result)[0] = std::move(fds[0]);
(*result)[1] = std::move(fds[1]);
return true;
}
template <typename T>
bool FuseMessage<T>::Read(int fd) {
return ReadInternal(this, fd, 0) == ResultOrAgain::kSuccess;
}
template <typename T>
ResultOrAgain FuseMessage<T>::ReadOrAgain(int fd) {
return ReadInternal(this, fd, MSG_DONTWAIT);
}
template <typename T>
bool FuseMessage<T>::Write(int fd) const {
return WriteInternal(this, fd, 0) == ResultOrAgain::kSuccess;
}
template <typename T>
ResultOrAgain FuseMessage<T>::WriteOrAgain(int fd) const {
return WriteInternal(this, fd, MSG_DONTWAIT);
}
template class FuseMessage<FuseRequest>;
template class FuseMessage<FuseResponse>;
void FuseRequest::Reset(
uint32_t data_length, uint32_t opcode, uint64_t unique) {
memset(this, 0, sizeof(fuse_in_header) + data_length);
header.len = sizeof(fuse_in_header) + data_length;
header.opcode = opcode;
header.unique = unique;
}
void FuseResponse::ResetHeader(
uint32_t data_length, int32_t error, uint64_t unique) {
CHECK_LE(error, 0) << "error should be zero or negative.";
header.len = sizeof(fuse_out_header) + data_length;
header.error = error;
header.unique = unique;
}
void FuseResponse::Reset(uint32_t data_length, int32_t error, uint64_t unique) {
memset(this, 0, sizeof(fuse_out_header) + data_length);
ResetHeader(data_length, error, unique);
}
void FuseBuffer::HandleInit() {
const fuse_init_in* const in = &request.init_in;
// Before writing |out|, we need to copy data from |in|.
const uint64_t unique = request.header.unique;
const uint32_t minor = in->minor;
const uint32_t max_readahead = in->max_readahead;
// Kernel 2.6.16 is the first stable kernel with struct fuse_init_out
// defined (fuse version 7.6). The structure is the same from 7.6 through
// 7.22. Beginning with 7.23, the structure increased in size and added
// new parameters.
if (in->major != FUSE_KERNEL_VERSION || in->minor < 6) {
LOG(ERROR) << "Fuse kernel version mismatch: Kernel version " << in->major
<< "." << in->minor << " Expected at least " << FUSE_KERNEL_VERSION
<< ".6";
response.Reset(0, -EPERM, unique);
return;
}
// We limit ourselves to minor=15 because we don't handle BATCH_FORGET yet.
// Thus we need to use FUSE_COMPAT_22_INIT_OUT_SIZE.
#if defined(FUSE_COMPAT_22_INIT_OUT_SIZE)
// FUSE_KERNEL_VERSION >= 23.
const size_t response_size = FUSE_COMPAT_22_INIT_OUT_SIZE;
#else
const size_t response_size = sizeof(fuse_init_out);
#endif
response.Reset(response_size, kFuseSuccess, unique);
fuse_init_out* const out = &response.init_out;
out->major = FUSE_KERNEL_VERSION;
out->minor = std::min(minor, 15u);
out->max_readahead = max_readahead;
out->flags = FUSE_ATOMIC_O_TRUNC | FUSE_BIG_WRITES;
out->max_background = 32;
out->congestion_threshold = 32;
out->max_write = kFuseMaxWrite;
}
void FuseBuffer::HandleNotImpl() {
LOG(VERBOSE) << "NOTIMPL op=" << request.header.opcode << " uniq="
<< request.header.unique << " nid=" << request.header.nodeid;
const uint64_t unique = request.header.unique;
response.Reset(0, -ENOSYS, unique);
}
} // namespace fuse
} // namespace android
|