src/basic/socket-label.c

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <errno.h>
#include <netinet/in.h>
#include <stdbool.h>
#include <stddef.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>

#include "alloc-util.h"
#include "fd-util.h"
#include "log.h"
#include "macro.h"
#include "missing.h"
#include "mkdir.h"
#include "selinux-util.h"
#include "socket-util.h"
#include "umask-util.h"

int socket_address_listen(
                const SocketAddress *a,
                int flags,
                int backlog,
                SocketAddressBindIPv6Only only,
                const char *bind_to_device,
                bool reuse_port,
                bool free_bind,
                bool transparent,
                mode_t directory_mode,
                mode_t socket_mode,
                const char *label) {

        _cleanup_close_ int fd = -1;
        int r, one;

        assert(a);

        r = socket_address_verify(a);
        if (r < 0)
                return r;

        if (socket_address_family(a) == AF_INET6 && !socket_ipv6_is_supported())
                return -EAFNOSUPPORT;

        if (label) {
                r = mac_selinux_create_socket_prepare(label);
                if (r < 0)
                        return r;
        }

        fd = socket(socket_address_family(a), a->type | flags, a->protocol);
        r = fd < 0 ? -errno : 0;

        if (label)
                mac_selinux_create_socket_clear();

        if (r < 0)
                return r;

        if (socket_address_family(a) == AF_INET6 && only != SOCKET_ADDRESS_DEFAULT) {
                int flag = only == SOCKET_ADDRESS_IPV6_ONLY;

                if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &flag, sizeof(flag)) < 0)
                        return -errno;
        }

        if (IN_SET(socket_address_family(a), AF_INET, AF_INET6)) {
                if (bind_to_device)
                        if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, bind_to_device, strlen(bind_to_device)+1) < 0)
                                return -errno;

                if (reuse_port) {
                        one = 1;
                        if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one)) < 0)
                                log_warning_errno(errno, "SO_REUSEPORT failed: %m");
                }

                if (free_bind) {
                        one = 1;
                        if (setsockopt(fd, IPPROTO_IP, IP_FREEBIND, &one, sizeof(one)) < 0)
                                log_warning_errno(errno, "IP_FREEBIND failed: %m");
                }

                if (transparent) {
                        one = 1;
                        if (setsockopt(fd, IPPROTO_IP, IP_TRANSPARENT, &one, sizeof(one)) < 0)
                                log_warning_errno(errno, "IP_TRANSPARENT failed: %m");
                }
        }

        one = 1;
        if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) < 0)
                return -errno;

        if (socket_address_family(a) == AF_UNIX && a->sockaddr.un.sun_path[0] != 0) {
                /* Create parents */
                (void) mkdir_parents_label(a->sockaddr.un.sun_path, directory_mode);

                /* Enforce the right access mode for the socket */
                RUN_WITH_UMASK(~socket_mode) {
                        r = mac_selinux_bind(fd, &a->sockaddr.sa, a->size);
                        if (r == -EADDRINUSE) {
                                /* Unlink and try again */
                                unlink(a->sockaddr.un.sun_path);
                                if (bind(fd, &a->sockaddr.sa, a->size) < 0)
                                        return -errno;
                        } else if (r < 0)
                                return r;
                }
        } else {
                if (bind(fd, &a->sockaddr.sa, a->size) < 0)
                        return -errno;
        }

        if (socket_address_can_accept(a))
                if (listen(fd, backlog) < 0)
                        return -errno;

        r = fd;
        fd = -1;

        return r;
}

int make_socket_fd(int log_level, const char* address, int type, int flags) {
        SocketAddress a;
        int fd, r;

        r = socket_address_parse(&a, address);
        if (r < 0)
                return log_error_errno(r, "Failed to parse socket address \"%s\": %m", address);

        a.type = type;

        fd = socket_address_listen(&a, type | flags, SOMAXCONN, SOCKET_ADDRESS_DEFAULT,
                                   NULL, false, false, false, 0755, 0644, NULL);
        if (fd < 0 || log_get_max_level() >= log_level) {
                _cleanup_free_ char *p = NULL;

                r = socket_address_print(&a, &p);
                if (r < 0)
                        return log_error_errno(r, "socket_address_print(): %m");

                if (fd < 0)
                        log_error_errno(fd, "Failed to listen on %s: %m", p);
                else
                        log_full(log_level, "Listening on %s", p);
        }

        return fd;
}