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// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ipc/unix_domain_socket_util.h"
#include <errno.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/files/scoped_file.h"
#include "base/logging.h"
#include "base/posix/eintr_wrapper.h"
#include "build/build_config.h"
namespace IPC {
// Verify that kMaxSocketNameLength is a decent size.
static_assert(sizeof(((sockaddr_un*)0)->sun_path) >= kMaxSocketNameLength,
"sun_path is too long.");
namespace {
// This function fills in |unix_addr| with the appropriate data for the socket,
// and sets |unix_addr_len| to the length of the data therein.
// Returns true on success, or false on failure (typically because |socket_name|
// violated the naming rules).
bool MakeUnixAddrForPath(const std::string& socket_name,
struct sockaddr_un* unix_addr,
size_t* unix_addr_len) {
DCHECK(unix_addr);
DCHECK(unix_addr_len);
if (socket_name.length() == 0) {
LOG(ERROR) << "Empty socket name provided for unix socket address.";
return false;
}
// We reject socket_name.length() == kMaxSocketNameLength to make room for
// the NUL terminator at the end of the string.
if (socket_name.length() >= kMaxSocketNameLength) {
LOG(ERROR) << "Socket name too long: " << socket_name;
return false;
}
// Create unix_addr structure.
memset(unix_addr, 0, sizeof(struct sockaddr_un));
unix_addr->sun_family = AF_UNIX;
strncpy(unix_addr->sun_path, socket_name.c_str(), kMaxSocketNameLength);
*unix_addr_len =
offsetof(struct sockaddr_un, sun_path) + socket_name.length();
return true;
}
// This functions creates a unix domain socket, and set it as non-blocking.
// If successful, |out_fd| will be set to the new file descriptor, and the
// function will return true. Otherwise returns false.
bool CreateUnixDomainSocket(base::ScopedFD* out_fd) {
DCHECK(out_fd);
// Create the unix domain socket.
base::ScopedFD fd(socket(AF_UNIX, SOCK_STREAM, 0));
if (!fd.is_valid()) {
PLOG(ERROR) << "Failed to create AF_UNIX socket.";
return false;
}
// Now set it as non-blocking.
if (!base::SetNonBlocking(fd.get())) {
PLOG(ERROR) << "base::SetNonBlocking() failed " << fd.get();
return false;
}
fd.swap(*out_fd);
return true;
}
bool IsRecoverableError() {
return errno == ECONNABORTED || errno == EMFILE || errno == ENFILE ||
errno == ENOMEM || errno == ENOBUFS;
}
} // namespace
bool CreateServerUnixDomainSocket(const base::FilePath& socket_path,
int* server_listen_fd) {
DCHECK(server_listen_fd);
// Make sure the path we need exists.
base::FilePath socket_dir = socket_path.DirName();
if (!base::CreateDirectory(socket_dir)) {
LOG(ERROR) << "Couldn't create directory: " << socket_dir.value();
return false;
}
const std::string socket_name = socket_path.value();
// Delete any old FS instances.
if (unlink(socket_name.c_str()) < 0 && errno != ENOENT) {
PLOG(ERROR) << "unlink " << socket_name;
return false;
}
struct sockaddr_un unix_addr;
size_t unix_addr_len;
if (!MakeUnixAddrForPath(socket_name, &unix_addr, &unix_addr_len))
return false;
base::ScopedFD fd;
if (!CreateUnixDomainSocket(&fd))
return false;
// Bind the socket.
if (bind(fd.get(), reinterpret_cast<const sockaddr*>(&unix_addr),
unix_addr_len) < 0) {
PLOG(ERROR) << "bind " << socket_name;
return false;
}
// Start listening on the socket.
if (listen(fd.get(), SOMAXCONN) < 0) {
PLOG(ERROR) << "listen " << socket_name;
unlink(socket_name.c_str());
return false;
}
*server_listen_fd = fd.release();
return true;
}
bool CreateClientUnixDomainSocket(const base::FilePath& socket_path,
int* client_socket) {
DCHECK(client_socket);
struct sockaddr_un unix_addr;
size_t unix_addr_len;
if (!MakeUnixAddrForPath(socket_path.value(), &unix_addr, &unix_addr_len))
return false;
base::ScopedFD fd;
if (!CreateUnixDomainSocket(&fd))
return false;
if (HANDLE_EINTR(connect(fd.get(), reinterpret_cast<sockaddr*>(&unix_addr),
unix_addr_len)) < 0) {
PLOG(ERROR) << "connect " << socket_path.value();
return false;
}
*client_socket = fd.release();
return true;
}
bool GetPeerEuid(int fd, uid_t* peer_euid) {
DCHECK(peer_euid);
#if defined(OS_MACOSX) || defined(OS_OPENBSD) || defined(OS_FREEBSD)
uid_t socket_euid;
gid_t socket_gid;
if (getpeereid(fd, &socket_euid, &socket_gid) < 0) {
PLOG(ERROR) << "getpeereid " << fd;
return false;
}
*peer_euid = socket_euid;
return true;
#else
struct ucred cred;
socklen_t cred_len = sizeof(cred);
if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &cred_len) < 0) {
PLOG(ERROR) << "getsockopt " << fd;
return false;
}
if (static_cast<unsigned>(cred_len) < sizeof(cred)) {
NOTREACHED() << "Truncated ucred from SO_PEERCRED?";
return false;
}
*peer_euid = cred.uid;
return true;
#endif
}
bool IsPeerAuthorized(int peer_fd) {
uid_t peer_euid;
if (!GetPeerEuid(peer_fd, &peer_euid))
return false;
if (peer_euid != geteuid()) {
DLOG(ERROR) << "Client euid is not authorised";
return false;
}
return true;
}
bool ServerAcceptConnection(int server_listen_fd, int* server_socket) {
DCHECK(server_socket);
*server_socket = -1;
base::ScopedFD accept_fd(HANDLE_EINTR(accept(server_listen_fd, NULL, 0)));
if (!accept_fd.is_valid())
return IsRecoverableError();
if (!base::SetNonBlocking(accept_fd.get())) {
PLOG(ERROR) << "base::SetNonBlocking() failed " << accept_fd.get();
// It's safe to keep listening on |server_listen_fd| even if the attempt to
// set O_NONBLOCK failed on the client fd.
return true;
}
*server_socket = accept_fd.release();
return true;
}
} // namespace IPC
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