/*
* 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 <sys/uio.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/macros.h>
namespace android {
namespace fuse {
namespace {
constexpr useconds_t kRetrySleepForWriting = 1000; // 1 ms
template <typename T>
bool CheckHeaderLength(const FuseMessage<T>* self, const char* name, size_t max_size) {
const auto& header = static_cast<const T*>(self)->header;
if (header.len >= sizeof(header) && header.len <= max_size) {
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", sizeof(T))) {
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, const void* data,
size_t max_size) {
if (!CheckHeaderLength<T>(self, "Write", max_size)) {
return ResultOrAgain::kFailure;
}
const char* const buf = reinterpret_cast<const char*>(self);
const auto& header = static_cast<const T*>(self)->header;
while (true) {
int result;
if (sockflag) {
CHECK(data == nullptr);
result = TEMP_FAILURE_RETRY(send(fd, buf, header.len, sockflag));
} else if (data) {
const struct iovec vec[] = {{const_cast<char*>(buf), sizeof(header)},
{const_cast<void*>(data), header.len - sizeof(header)}};
result = TEMP_FAILURE_RETRY(writev(fd, vec, arraysize(vec)));
} else {
result = TEMP_FAILURE_RETRY(write(fd, buf, header.len));
}
if (result == -1) {
switch (errno) {
case ENOBUFS:
// When returning ENOBUFS, epoll still reports the FD is writable. Just usleep
// and retry again.
usleep(kRetrySleepForWriting);
continue;
case EAGAIN:
return ResultOrAgain::kAgain;
default:
PLOG(ERROR) << "Failed to write a FUSE message: "
<< "fd=" << fd << " "
<< "sockflag=" << sockflag << " "
<< "data=" << data;
return ResultOrAgain::kFailure;
}
}
if (static_cast<unsigned int>(result) != header.len) {
LOG(ERROR) << "Written bytes " << result << " is different from length in header "
<< header.len;
return ResultOrAgain::kFailure;
}
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, nullptr, sizeof(T)) == ResultOrAgain::kSuccess;
}
template <typename T>
bool FuseMessage<T>::WriteWithBody(int fd, size_t max_size, const void* data) const {
CHECK(data != nullptr);
return WriteInternal(this, fd, 0, data, max_size) == ResultOrAgain::kSuccess;
}
template <typename T>
ResultOrAgain FuseMessage<T>::WriteOrAgain(int fd) const {
return WriteInternal(this, fd, MSG_DONTWAIT, nullptr, sizeof(T));
}
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;
}
template <size_t N>
void FuseResponseBase<N>::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;
}
template <size_t N>
void FuseResponseBase<N>::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;
// Add volatile as a workaround for compiler issue which removes the temporary
// variable.
const volatile uint64_t unique = request.header.unique;
response.Reset(0, -ENOSYS, unique);
}
template class FuseMessage<FuseRequest>;
template class FuseMessage<FuseResponse>;
template class FuseMessage<FuseSimpleResponse>;
template struct FuseResponseBase<0u>;
template struct FuseResponseBase<kFuseMaxRead>;
} // namespace fuse
} // namespace android