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/* bubblewrap
* Copyright (C) 2016 Alexander Larsson
*
* This program 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 of the License, or (at your option) any later version.
*
* This library 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 library. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "config.h"
#include <arpa/inet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <linux/loop.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include "utils.h"
#include "network.h"
static void *
add_rta (struct nlmsghdr *header,
int type,
size_t size)
{
struct rtattr *rta;
size_t rta_size = RTA_LENGTH (size);
rta = (struct rtattr *) ((char *) header + NLMSG_ALIGN (header->nlmsg_len));
rta->rta_type = type;
rta->rta_len = rta_size;
header->nlmsg_len = NLMSG_ALIGN (header->nlmsg_len) + rta_size;
return RTA_DATA (rta);
}
static int
rtnl_send_request (int rtnl_fd,
struct nlmsghdr *header)
{
struct sockaddr_nl dst_addr = { AF_NETLINK, 0 };
ssize_t sent;
sent = sendto (rtnl_fd, (void *) header, header->nlmsg_len, 0,
(struct sockaddr *) &dst_addr, sizeof (dst_addr));
if (sent < 0)
return -1;
return 0;
}
static int
rtnl_read_reply (int rtnl_fd,
int seq_nr)
{
char buffer[1024];
ssize_t received;
struct nlmsghdr *rheader;
while (1)
{
received = recv (rtnl_fd, buffer, sizeof (buffer), 0);
if (received < 0)
return -1;
rheader = (struct nlmsghdr *) buffer;
while (received >= NLMSG_HDRLEN)
{
if (rheader->nlmsg_seq != seq_nr)
return -1;
if (rheader->nlmsg_pid != getpid ())
return -1;
if (rheader->nlmsg_type == NLMSG_ERROR)
{
uint32_t *err = NLMSG_DATA (rheader);
if (*err == 0)
return 0;
return -1;
}
if (rheader->nlmsg_type == NLMSG_DONE)
return 0;
rheader = NLMSG_NEXT (rheader, received);
}
}
}
static int
rtnl_do_request (int rtnl_fd,
struct nlmsghdr *header)
{
if (rtnl_send_request (rtnl_fd, header) != 0)
return -1;
if (rtnl_read_reply (rtnl_fd, header->nlmsg_seq) != 0)
return -1;
return 0;
}
static struct nlmsghdr *
rtnl_setup_request (char *buffer,
int type,
int flags,
size_t size)
{
struct nlmsghdr *header;
size_t len = NLMSG_LENGTH (size);
static uint32_t counter = 0;
memset (buffer, 0, len);
header = (struct nlmsghdr *) buffer;
header->nlmsg_len = len;
header->nlmsg_type = type;
header->nlmsg_flags = flags | NLM_F_REQUEST;
header->nlmsg_seq = counter++;
header->nlmsg_pid = getpid ();
return (struct nlmsghdr *) header;
}
void
loopback_setup (void)
{
int r, if_loopback;
cleanup_fd int rtnl_fd = -1;
char buffer[1024];
struct sockaddr_nl src_addr = { AF_NETLINK, 0 };
struct nlmsghdr *header;
struct ifaddrmsg *addmsg;
struct ifinfomsg *infomsg;
struct in_addr *ip_addr;
src_addr.nl_pid = getpid ();
if_loopback = (int) if_nametoindex ("lo");
if (if_loopback <= 0)
die_with_error ("loopback: Failed to look up lo");
rtnl_fd = socket (PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
if (rtnl_fd < 0)
die_with_error ("loopback: Failed to create NETLINK_ROUTE socket");
r = bind (rtnl_fd, (struct sockaddr *) &src_addr, sizeof (src_addr));
if (r < 0)
die_with_error ("loopback: Failed to bind NETLINK_ROUTE socket");
header = rtnl_setup_request (buffer, RTM_NEWADDR,
NLM_F_CREATE | NLM_F_EXCL | NLM_F_ACK,
sizeof (struct ifaddrmsg));
addmsg = NLMSG_DATA (header);
addmsg->ifa_family = AF_INET;
addmsg->ifa_prefixlen = 8;
addmsg->ifa_flags = IFA_F_PERMANENT;
addmsg->ifa_scope = RT_SCOPE_HOST;
addmsg->ifa_index = if_loopback;
ip_addr = add_rta (header, IFA_LOCAL, sizeof (*ip_addr));
ip_addr->s_addr = htonl (INADDR_LOOPBACK);
ip_addr = add_rta (header, IFA_ADDRESS, sizeof (*ip_addr));
ip_addr->s_addr = htonl (INADDR_LOOPBACK);
assert (header->nlmsg_len < sizeof (buffer));
if (rtnl_do_request (rtnl_fd, header) != 0)
die_with_error ("loopback: Failed RTM_NEWADDR");
header = rtnl_setup_request (buffer, RTM_NEWLINK,
NLM_F_ACK,
sizeof (struct ifinfomsg));
infomsg = NLMSG_DATA (header);
infomsg->ifi_family = AF_UNSPEC;
infomsg->ifi_type = 0;
infomsg->ifi_index = if_loopback;
infomsg->ifi_flags = IFF_UP;
infomsg->ifi_change = IFF_UP;
assert (header->nlmsg_len < sizeof (buffer));
if (rtnl_do_request (rtnl_fd, header) != 0)
die_with_error ("loopback: Failed RTM_NEWLINK");
}
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