/*
* Copyright © 2014 Canonical Ltd.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see .
*
* Authored by: Kevin DuBois
*/
#include "anbox/network/fd_socket_transmission.h"
#include "anbox/common/variable_length_array.h"
#include
#include
#include
#include
#include
#include
namespace anbox {
socket_error::socket_error(std::string const& message)
: std::system_error(errno, std::system_category(), message) {}
socket_disconnected_error::socket_disconnected_error(std::string const& message)
: std::system_error(errno, std::system_category(), message) {}
fd_reception_error::fd_reception_error(std::string const& message)
: std::runtime_error(message) {}
void send_fds(Fd const& socket, std::vector const& fds) {
if (fds.size() > 0) {
// We send dummy data
struct iovec iov;
char dummy_iov_data = 'M';
iov.iov_base = &dummy_iov_data;
iov.iov_len = 1;
// Allocate space for control message
static auto const builtin_n_fds = 5;
static auto const builtin_cmsg_space =
CMSG_SPACE(builtin_n_fds * sizeof(int));
auto const fds_bytes = fds.size() * sizeof(int);
VariableLengthArray control{CMSG_SPACE(fds_bytes)};
// Silence valgrind uninitialized memory complaint
memset(control.data(), 0, control.size());
// Message to send
struct msghdr header;
header.msg_name = NULL;
header.msg_namelen = 0;
header.msg_iov = &iov;
header.msg_iovlen = 1;
header.msg_controllen = control.size();
header.msg_control = control.data();
header.msg_flags = 0;
// Control message contains file descriptors
struct cmsghdr* message = CMSG_FIRSTHDR(&header);
message->cmsg_len = CMSG_LEN(fds_bytes);
message->cmsg_level = SOL_SOCKET;
message->cmsg_type = SCM_RIGHTS;
int* const data = reinterpret_cast(CMSG_DATA(message));
int i = 0;
for (auto& fd : fds) data[i++] = fd;
auto const sent = sendmsg(socket, &header, MSG_NOSIGNAL);
if (sent < 0)
BOOST_THROW_EXCEPTION(std::runtime_error("Failed to send fds: " +
std::string(strerror(errno))));
}
}
bool socket_error_is_transient(int error_code) { return (error_code == EINTR); }
void receive_data(Fd const& socket, void* buffer, size_t bytes_requested,
std::vector& fds) {
if (bytes_requested == 0)
BOOST_THROW_EXCEPTION(std::logic_error("Attempted to receive 0 bytes"));
size_t bytes_read{0};
unsigned fds_read{0};
while (bytes_read < bytes_requested) {
// Store the data in the buffer requested
struct iovec iov;
iov.iov_base = static_cast(buffer) + bytes_read;
iov.iov_len = bytes_requested - bytes_read;
// Allocate space for control message
static auto const builtin_n_fds = 5;
static auto const builtin_cmsg_space =
CMSG_SPACE(builtin_n_fds * sizeof(int));
auto const fds_bytes = (fds.size() - fds_read) * sizeof(int);
VariableLengthArray control{CMSG_SPACE(fds_bytes)};
// Message to read
struct msghdr header;
header.msg_name = NULL;
header.msg_namelen = 0;
header.msg_iov = &iov;
header.msg_iovlen = 1;
header.msg_controllen = control.size();
header.msg_control = control.data();
header.msg_flags = 0;
ssize_t const result = recvmsg(socket, &header, MSG_NOSIGNAL | MSG_WAITALL);
if (result == 0)
BOOST_THROW_EXCEPTION(socket_disconnected_error(
"Failed to read message from server: server has shutdown"));
if (result < 0) {
if (socket_error_is_transient(errno)) continue;
if (errno == EAGAIN) continue;
if (errno == EPIPE)
BOOST_THROW_EXCEPTION(
boost::enable_error_info(
socket_disconnected_error("Failed to read message from server"))
<< boost::errinfo_errno(errno));
BOOST_THROW_EXCEPTION(boost::enable_error_info(socket_error(
"Failed to read message from server"))
<< boost::errinfo_errno(errno));
}
bytes_read += result;
// If we get a proper control message, copy the received
// file descriptors back to the caller
struct cmsghdr const* const cmsg = CMSG_FIRSTHDR(&header);
if (cmsg) {
if ((cmsg->cmsg_level == SOL_SOCKET) &&
(cmsg->cmsg_type == SCM_CREDENTIALS))
BOOST_THROW_EXCEPTION(
fd_reception_error("received SCM_CREDENTIALS when expecting fd"));
if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS)
BOOST_THROW_EXCEPTION(fd_reception_error(
"Invalid control message for receiving file descriptors"));
int const* const data = reinterpret_cast CMSG_DATA(cmsg);
ptrdiff_t const header_size = reinterpret_cast(data) -
reinterpret_cast(cmsg);
int const nfds = (cmsg->cmsg_len - header_size) / sizeof(int);
// NOTE: This relies on the file descriptor cmsg being read
// (and written) atomically.
if (cmsg->cmsg_len > CMSG_LEN(fds_bytes) ||
(header.msg_flags & MSG_CTRUNC)) {
for (int i = 0; i < nfds; i++) ::close(data[i]);
BOOST_THROW_EXCEPTION(
std::runtime_error("Received more fds than expected"));
}
// We can't properly pass Fds through google::protobuf::Message,
// which is where these get shoved.
//
// When we have our own RPC generator plugin and aren't using deprecated
// Protobuf features this can go away.
for (int i = 0; i < nfds; i++)
fds[fds_read + i] = Fd{IntOwnedFd{data[i]}};
fds_read += nfds;
}
}
if (fds_read < fds.size()) {
for (auto fd : fds)
if (fd >= 0) ::close(fd);
fds.clear();
BOOST_THROW_EXCEPTION(
std::runtime_error("Received fewer fds than expected"));
}
}
} // namespace anbox