glibc/support/support_enter_network_namespace.c

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/* Enter a network namespace.
Copyright (C) 2016-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library 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.
The GNU C 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 the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <support/namespace.h>
#include <net/if.h>
#include <sched.h>
#include <stdio.h>
#include <string.h>
#include <support/check.h>
#include <support/xsocket.h>
#include <support/xunistd.h>
#include <sys/ioctl.h>
#include <unistd.h>
static bool in_uts_namespace;
bool
support_enter_network_namespace (void)
{
#ifdef CLONE_NEWUTS
if (unshare (CLONE_NEWUTS) == 0)
in_uts_namespace = true;
else
printf ("warning: unshare (CLONE_NEWUTS) failed: %m\n");
#endif
#ifdef CLONE_NEWNET
if (unshare (CLONE_NEWNET) == 0)
{
/* Bring up the loopback interface. */
int fd = xsocket (AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
struct ifreq req;
strcpy (req.ifr_name, "lo");
TEST_VERIFY_EXIT (ioctl (fd, SIOCGIFFLAGS, &req) == 0);
bool already_up = req.ifr_flags & IFF_UP;
if (already_up)
/* This means that we likely have not achieved isolation from
the parent namespace. */
printf ("warning: loopback interface already exists"
" in new network namespace\n");
else
{
req.ifr_flags |= IFF_UP | IFF_RUNNING;
TEST_VERIFY_EXIT (ioctl (fd, SIOCSIFFLAGS, &req) == 0);
}
xclose (fd);
return !already_up;
}
#endif
printf ("warning: could not enter network namespace\n");
return false;
}
bool
support_in_uts_namespace (void)
{
return in_uts_namespace;
}