src/core/loopback-setup.c - systemd-stable - Rivoreo Source Code Repositories

 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

 /***
   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 <sys/socket.h>
 #include <net/if.h>
 #include <asm/types.h>
 #include <netinet/in.h>
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>

 #include "util.h"
 #include "macro.h"
 #include "loopback-setup.h"
 #include "socket-util.h"

 #define NLMSG_TAIL(nmsg)                                                \
         ((struct rtattr *) (((uint8_t*) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))

 static int add_rtattr(struct nlmsghdr *n, size_t max_length, int type, const void *data, size_t data_length) {
         size_t length;
         struct rtattr *rta;

         length = RTA_LENGTH(data_length);

         if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length) > max_length)
                 return -E2BIG;

         rta = NLMSG_TAIL(n);
         rta->rta_type = type;
         rta->rta_len = length;
         memcpy(RTA_DATA(rta), data, data_length);
         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length);

         return 0;
 }

 static ssize_t sendto_loop(int fd, const void *buf, size_t buf_len, int flags, const struct sockaddr *sa, socklen_t sa_len) {

         for (;;) {
                 ssize_t l;

                 l = sendto(fd, buf, buf_len, flags, sa, sa_len);
                 if (l >= 0)
                         return l;

                 if (errno != EINTR)
                         return -errno;
         }
 }

 static ssize_t recvfrom_loop(int fd, void *buf, size_t buf_len, int flags, struct sockaddr *sa, socklen_t *sa_len) {

         for (;;) {
                 ssize_t l;

                 l = recvfrom(fd, buf, buf_len, flags, sa, sa_len);
                 if (l >= 0)
                         return l;

                 if (errno != EINTR)
                         return -errno;
         }
 }

 static int add_adresses(int fd, int if_loopback, unsigned *requests) {
         union {
                 struct sockaddr sa;
                 struct sockaddr_nl nl;
         } sa = {
                 .nl.nl_family = AF_NETLINK,
         };

         union {
                 struct nlmsghdr header;
                 uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
                             NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
                             RTA_LENGTH(sizeof(struct in6_addr))];
         } request = {
                 .header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)),
                 .header.nlmsg_type = RTM_NEWADDR,
                 .header.nlmsg_flags = NLM_F_REQUEST|NLM_F_CREATE|NLM_F_ACK,
                 .header.nlmsg_seq = *requests + 1,
         };

         struct ifaddrmsg *ifaddrmsg;
         uint32_t ipv4_address = htonl(INADDR_LOOPBACK);
         int r;

         ifaddrmsg = NLMSG_DATA(&request.header);
         ifaddrmsg->ifa_family = AF_INET;
         ifaddrmsg->ifa_prefixlen = 8;
         ifaddrmsg->ifa_flags = IFA_F_PERMANENT;
         ifaddrmsg->ifa_scope = RT_SCOPE_HOST;
         ifaddrmsg->ifa_index = if_loopback;

         r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL,
                        &ipv4_address, sizeof(ipv4_address));
         if (r < 0)
                 return r;

         if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0)
                 return -errno;
         (*requests)++;

         if (!socket_ipv6_is_supported())
                 return 0;

         request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
         request.header.nlmsg_seq = *requests + 1;

         ifaddrmsg->ifa_family = AF_INET6;
         ifaddrmsg->ifa_prefixlen = 128;

         r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL,
                        &in6addr_loopback, sizeof(in6addr_loopback));
         if (r < 0)
                 return r;

         if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0)
                 return -errno;
         (*requests)++;

         return 0;
 }

 static int start_interface(int fd, int if_loopback, unsigned *requests) {
         union {
                 struct sockaddr sa;
                 struct sockaddr_nl nl;
         } sa = {
                 .nl.nl_family = AF_NETLINK,
         };

         union {
                 struct nlmsghdr header;
                 uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
                             NLMSG_ALIGN(sizeof(struct ifinfomsg))];
         } request = {
                 .header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
                 .header.nlmsg_type = RTM_NEWLINK,
                 .header.nlmsg_flags = NLM_F_REQUEST|NLM_F_ACK,
                 .header.nlmsg_seq = *requests + 1,
         };

         struct ifinfomsg *ifinfomsg;

         ifinfomsg = NLMSG_DATA(&request.header);
         ifinfomsg->ifi_family = AF_UNSPEC;
         ifinfomsg->ifi_index = if_loopback;
         ifinfomsg->ifi_flags = IFF_UP;
         ifinfomsg->ifi_change = IFF_UP;

         if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0)
                 return -errno;

         (*requests)++;

         return 0;
 }

 static int read_response(int fd, unsigned requests_max) {
         union {
                 struct sockaddr sa;
                 struct sockaddr_nl nl;
         } sa;
         union {
                 struct nlmsghdr header;
                 uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
                             NLMSG_ALIGN(sizeof(struct nlmsgerr))];
         } response;

         ssize_t l;
         socklen_t sa_len = sizeof(sa);
         struct nlmsgerr *nlmsgerr;

         l = recvfrom_loop(fd, &response, sizeof(response), 0, &sa.sa, &sa_len);
         if (l < 0)
                 return -errno;

         if (sa_len != sizeof(sa.nl) ||
             sa.nl.nl_family != AF_NETLINK)
                 return -EIO;

         if (sa.nl.nl_pid != 0)
                 return 0;

         if ((size_t) l < sizeof(struct nlmsghdr))
                 return -EIO;

         if (response.header.nlmsg_type != NLMSG_ERROR ||
             (pid_t) response.header.nlmsg_pid != getpid() ||
             response.header.nlmsg_seq >= requests_max)
                 return 0;

         if ((size_t) l < NLMSG_LENGTH(sizeof(struct nlmsgerr)) ||
             response.header.nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
                 return -EIO;

         nlmsgerr = NLMSG_DATA(&response.header);

         if (nlmsgerr->error < 0 && nlmsgerr->error != -EEXIST)
                 return nlmsgerr->error;

         return response.header.nlmsg_seq;
 }

 static int check_loopback(void) {
         int r;
         _cleanup_close_ int fd;
         union {
                 struct sockaddr sa;
                 struct sockaddr_in in;
         } sa = {
                 .in.sin_family = AF_INET,
                 .in.sin_addr.s_addr = INADDR_LOOPBACK,
         };

         /* If we failed to set up the loop back device, check whether
          * it might already be set up */

         fd = socket(AF_INET, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
         if (fd < 0)
                 return -errno;

         if (bind(fd, &sa.sa, sizeof(sa.in)) >= 0)
                 r = 1;
         else
                 r = errno == EADDRNOTAVAIL ? 0 : -errno;

         return r;
 }

 int loopback_setup(void) {
         int r, if_loopback;
         union {
                 struct sockaddr sa;
                 struct sockaddr_nl nl;
         } sa = {
                 .nl.nl_family = AF_NETLINK,
         };
         unsigned requests = 0, i;
         _cleanup_close_ int fd = -1;
         bool eperm = false;

         errno = 0;
         if_loopback = (int) if_nametoindex("lo");
         if (if_loopback <= 0)
                 return errno ? -errno : -ENODEV;

         fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
         if (fd < 0)
                 return -errno;

         if (bind(fd, &sa.sa, sizeof(sa)) < 0) {
                 r = -errno;
                 goto error;
         }

         r = add_adresses(fd, if_loopback, &requests);
         if (r < 0)
                 goto error;

         r = start_interface(fd, if_loopback, &requests);
         if (r < 0)
                 goto error;

         for (i = 0; i < requests; i++) {
                 r = read_response(fd, requests);

                 if (r == -EPERM)
                         eperm = true;
                 else if (r  < 0)
                         goto error;
         }

         if (eperm && check_loopback() < 0) {
                 r = -EPERM;
                 goto error;
         }

         return 0;

 error:
         log_warning("Failed to configure loopback device: %s", strerror(-r));
         return r;
 }
	/-- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil --/

	/***
	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 <sys/socket.h>
	#include <net/if.h>
	#include <asm/types.h>
	#include <netinet/in.h>
	#include <string.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <linux/netlink.h>
	#include <linux/rtnetlink.h>

	#include "util.h"
	#include "macro.h"
	#include "loopback-setup.h"
	#include "socket-util.h"

	#define NLMSG_TAIL(nmsg) \
	((struct rtattr ) (((uint8_t) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))

	static int add_rtattr(struct nlmsghdr n, size_t max_length, int type, const void data, size_t data_length) {
	size_t length;
	struct rtattr *rta;

	length = RTA_LENGTH(data_length);

	if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length) > max_length)
	return -E2BIG;

	rta = NLMSG_TAIL(n);
	rta->rta_type = type;
	rta->rta_len = length;
	memcpy(RTA_DATA(rta), data, data_length);
	n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length);

	return 0;
	}

	static ssize_t sendto_loop(int fd, const void buf, size_t buf_len, int flags, const struct sockaddr sa, socklen_t sa_len) {

	for (;;) {
	ssize_t l;

	l = sendto(fd, buf, buf_len, flags, sa, sa_len);
	if (l >= 0)
	return l;

	if (errno != EINTR)
	return -errno;
	}
	}

	static ssize_t recvfrom_loop(int fd, void buf, size_t buf_len, int flags, struct sockaddr sa, socklen_t *sa_len) {

	for (;;) {
	ssize_t l;

	l = recvfrom(fd, buf, buf_len, flags, sa, sa_len);
	if (l >= 0)
	return l;

	if (errno != EINTR)
	return -errno;
	}
	}

	static int add_adresses(int fd, int if_loopback, unsigned *requests) {
	union {
	struct sockaddr sa;
	struct sockaddr_nl nl;
	} sa = {
	.nl.nl_family = AF_NETLINK,
	};

	union {
	struct nlmsghdr header;
	uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
	NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
	RTA_LENGTH(sizeof(struct in6_addr))];
	} request = {
	.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)),
	.header.nlmsg_type = RTM_NEWADDR,
	.header.nlmsg_flags = NLM_F_REQUEST\|NLM_F_CREATE\|NLM_F_ACK,
	.header.nlmsg_seq = *requests + 1,
	};

	struct ifaddrmsg *ifaddrmsg;
	uint32_t ipv4_address = htonl(INADDR_LOOPBACK);
	int r;

	ifaddrmsg = NLMSG_DATA(&request.header);
	ifaddrmsg->ifa_family = AF_INET;
	ifaddrmsg->ifa_prefixlen = 8;
	ifaddrmsg->ifa_flags = IFA_F_PERMANENT;
	ifaddrmsg->ifa_scope = RT_SCOPE_HOST;
	ifaddrmsg->ifa_index = if_loopback;

	r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL,
	&ipv4_address, sizeof(ipv4_address));
	if (r < 0)
	return r;

	if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0)
	return -errno;
	(*requests)++;

	if (!socket_ipv6_is_supported())
	return 0;

	request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
	request.header.nlmsg_seq = *requests + 1;

	ifaddrmsg->ifa_family = AF_INET6;
	ifaddrmsg->ifa_prefixlen = 128;

	r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL,
	&in6addr_loopback, sizeof(in6addr_loopback));
	if (r < 0)
	return r;

	if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0)
	return -errno;
	(*requests)++;

	return 0;
	}

	static int start_interface(int fd, int if_loopback, unsigned *requests) {
	union {
	struct sockaddr sa;
	struct sockaddr_nl nl;
	} sa = {
	.nl.nl_family = AF_NETLINK,
	};

	union {
	struct nlmsghdr header;
	uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
	NLMSG_ALIGN(sizeof(struct ifinfomsg))];
	} request = {
	.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
	.header.nlmsg_type = RTM_NEWLINK,
	.header.nlmsg_flags = NLM_F_REQUEST\|NLM_F_ACK,
	.header.nlmsg_seq = *requests + 1,
	};

	struct ifinfomsg *ifinfomsg;

	ifinfomsg = NLMSG_DATA(&request.header);
	ifinfomsg->ifi_family = AF_UNSPEC;
	ifinfomsg->ifi_index = if_loopback;
	ifinfomsg->ifi_flags = IFF_UP;
	ifinfomsg->ifi_change = IFF_UP;

	if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0)
	return -errno;

	(*requests)++;

	return 0;
	}

	static int read_response(int fd, unsigned requests_max) {
	union {
	struct sockaddr sa;
	struct sockaddr_nl nl;
	} sa;
	union {
	struct nlmsghdr header;
	uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
	NLMSG_ALIGN(sizeof(struct nlmsgerr))];
	} response;

	ssize_t l;
	socklen_t sa_len = sizeof(sa);
	struct nlmsgerr *nlmsgerr;

	l = recvfrom_loop(fd, &response, sizeof(response), 0, &sa.sa, &sa_len);
	if (l < 0)
	return -errno;

	if (sa_len != sizeof(sa.nl) \|\|
	sa.nl.nl_family != AF_NETLINK)
	return -EIO;

	if (sa.nl.nl_pid != 0)
	return 0;

	if ((size_t) l < sizeof(struct nlmsghdr))
	return -EIO;

	if (response.header.nlmsg_type != NLMSG_ERROR \|\|
	(pid_t) response.header.nlmsg_pid != getpid() \|\|
	response.header.nlmsg_seq >= requests_max)
	return 0;

	if ((size_t) l < NLMSG_LENGTH(sizeof(struct nlmsgerr)) \|\|
	response.header.nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
	return -EIO;

	nlmsgerr = NLMSG_DATA(&response.header);

	if (nlmsgerr->error < 0 && nlmsgerr->error != -EEXIST)
	return nlmsgerr->error;

	return response.header.nlmsg_seq;
	}

	static int check_loopback(void) {
	int r;
	_cleanup_close_ int fd;
	union {
	struct sockaddr sa;
	struct sockaddr_in in;
	} sa = {
	.in.sin_family = AF_INET,
	.in.sin_addr.s_addr = INADDR_LOOPBACK,
	};

	/* If we failed to set up the loop back device, check whether
	* it might already be set up */

	fd = socket(AF_INET, SOCK_DGRAM\|SOCK_NONBLOCK\|SOCK_CLOEXEC, 0);
	if (fd < 0)
	return -errno;

	if (bind(fd, &sa.sa, sizeof(sa.in)) >= 0)
	r = 1;
	else
	r = errno == EADDRNOTAVAIL ? 0 : -errno;

	return r;
	}

	int loopback_setup(void) {
	int r, if_loopback;
	union {
	struct sockaddr sa;
	struct sockaddr_nl nl;
	} sa = {
	.nl.nl_family = AF_NETLINK,
	};
	unsigned requests = 0, i;
	_cleanup_close_ int fd = -1;
	bool eperm = false;

	errno = 0;
	if_loopback = (int) if_nametoindex("lo");
	if (if_loopback <= 0)
	return errno ? -errno : -ENODEV;

	fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (fd < 0)
	return -errno;

	if (bind(fd, &sa.sa, sizeof(sa)) < 0) {
	r = -errno;
	goto error;
	}

	r = add_adresses(fd, if_loopback, &requests);
	if (r < 0)
	goto error;

	r = start_interface(fd, if_loopback, &requests);
	if (r < 0)
	goto error;

	for (i = 0; i < requests; i++) {
	r = read_response(fd, requests);

	if (r == -EPERM)
	eperm = true;
	else if (r < 0)
	goto error;
	}

	if (eperm && check_loopback() < 0) {
	r = -EPERM;
	goto error;
	}

	return 0;

	error:
	log_warning("Failed to configure loopback device: %s", strerror(-r));
	return r;
	}