273 lines
7.0 KiB
C
273 lines
7.0 KiB
C
/*
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* Copyright (C) 2014-2017, Travelping GmbH <info@travelping.com>
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* Copyright (C) 2020, Harald Welte <laforge@gnumonks.org>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#if defined(__linux__)
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#ifndef _GNU_SOURCE
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# define _GNU_SOURCE
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#endif
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sched.h>
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#include <signal.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/socket.h>
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#include <sys/mount.h>
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#include <sys/param.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <osmocom/core/utils.h>
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#include "netns.h"
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#define NETNS_PATH "/var/run/netns"
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/*! default namespace of the GGSN process */
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static int default_nsfd = -1;
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/*! switch to a (non-default) namespace, store existing signal mask in oldmask.
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* \param[in] nsfd file descriptor representing the namespace to whch we shall switch
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* \param[out] oldmask caller-provided memory location to which old signal mask is stored
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* \ returns 0 on success or negative (errno) in case of error */
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int switch_ns(int nsfd, sigset_t *oldmask)
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{
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sigset_t intmask;
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int rc;
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OSMO_ASSERT(default_nsfd >= 0);
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if (sigfillset(&intmask) < 0)
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return -errno;
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if ((rc = sigprocmask(SIG_BLOCK, &intmask, oldmask)) != 0)
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return -rc;
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if (setns(nsfd, CLONE_NEWNET) < 0) {
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/* restore old mask if we couldn't switch the netns */
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sigprocmask(SIG_SETMASK, oldmask, NULL);
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return -errno;
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}
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return 0;
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}
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/*! switch back to the default namespace, restoring signal mask.
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* \param[in] oldmask signal mask to restore after returning to default namespace
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* \returns 0 on successs; negative errno value in case of error */
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int restore_ns(sigset_t *oldmask)
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{
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OSMO_ASSERT(default_nsfd >= 0);
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int rc;
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if (setns(default_nsfd, CLONE_NEWNET) < 0)
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return -errno;
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if ((rc = sigprocmask(SIG_SETMASK, oldmask, NULL)) != 0)
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return -rc;
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return 0;
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}
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/*! open a file from within specified network namespace */
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int open_ns(int nsfd, const char *pathname, int flags)
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{
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sigset_t intmask, oldmask;
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int ret;
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int fd = -1;
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int rc;
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OSMO_ASSERT(default_nsfd >= 0);
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/* mask off all signals, store old signal mask */
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if (sigfillset(&intmask) < 0)
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return -errno;
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if ((rc = sigprocmask(SIG_BLOCK, &intmask, &oldmask)) != 0)
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return -rc;
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/* associate the calling thread with namespace file descriptor */
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if (setns(nsfd, CLONE_NEWNET) < 0) {
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ret = -errno;
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goto restore_sigmask;
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}
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/* open the requested file/path */
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if ((fd = open(pathname, flags)) < 0) {
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ret = -errno;
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goto restore_defaultns;
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}
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ret = fd;
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restore_defaultns:
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/* return back to default namespace */
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if (setns(default_nsfd, CLONE_NEWNET) < 0) {
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if (fd >= 0)
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close(fd);
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return -errno;
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}
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restore_sigmask:
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/* restore process mask */
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if ((rc = sigprocmask(SIG_SETMASK, &oldmask, NULL)) != 0) {
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if (fd >= 0)
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close(fd);
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return -rc;
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}
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return ret;
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}
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/*! create a socket in another namespace.
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* Switches temporarily to namespace indicated by nsfd, creates a socket in
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* that namespace and then returns to the default namespace.
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* \param[in] nsfd File descriptor of the namspace in which to create socket
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* \param[in] domain Domain of the socket (AF_INET, ...)
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* \param[in] type Type of the socket (SOCK_STREAM, ...)
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* \param[in] protocol Protocol of the socket (IPPROTO_TCP, ...)
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* \returns 0 on success; negative errno in case of error */
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int socket_ns(int nsfd, int domain, int type, int protocol)
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{
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sigset_t intmask, oldmask;
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int ret;
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int sk = -1;
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int rc;
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OSMO_ASSERT(default_nsfd >= 0);
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/* mask off all signals, store old signal mask */
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if (sigfillset(&intmask) < 0)
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return -errno;
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if ((rc = sigprocmask(SIG_BLOCK, &intmask, &oldmask)) != 0)
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return -rc;
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/* associate the calling thread with namespace file descriptor */
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if (setns(nsfd, CLONE_NEWNET) < 0) {
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ret = -errno;
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goto restore_sigmask;
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}
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/* create socket of requested domain/type/proto */
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if ((sk = socket(domain, type, protocol)) < 0) {
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ret = -errno;
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goto restore_defaultns;
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}
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ret = sk;
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restore_defaultns:
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/* return back to default namespace */
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if (setns(default_nsfd, CLONE_NEWNET) < 0) {
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if (sk >= 0)
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close(sk);
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return -errno;
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}
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restore_sigmask:
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/* restore process mask */
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if ((rc = sigprocmask(SIG_SETMASK, &oldmask, NULL)) != 0) {
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if (sk >= 0)
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close(sk);
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return -rc;
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}
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return ret;
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}
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/*! initialize this network namespace helper module.
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* Must be called before using any other functions of this file.
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* \returns 0 on success; negative errno in case of error */
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int init_netns()
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{
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/* store the default namespace for later reference */
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if ((default_nsfd = open("/proc/self/ns/net", O_RDONLY)) < 0)
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return -errno;
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return 0;
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}
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/*! create obtain file descriptor for network namespace of give name.
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* Creates /var/run/netns if it doesn't exist already.
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* \param[in] name Name of the network namespace (in /var/run/netns/)
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* \returns File descriptor of network namespace; negative errno in case of error */
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int get_nsfd(const char *name)
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{
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int ret = 0;
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int rc;
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int fd;
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sigset_t intmask, oldmask;
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char path[MAXPATHLEN] = NETNS_PATH;
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OSMO_ASSERT(default_nsfd >= 0);
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/* create /var/run/netns, if it doesn't exist already */
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rc = mkdir(path, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
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if (rc < 0 && errno != EEXIST)
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return rc;
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/* create /var/run/netns/[name], if it doesn't exist already */
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snprintf(path, sizeof(path), "%s/%s", NETNS_PATH, name);
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fd = open(path, O_RDONLY|O_CREAT|O_EXCL, 0);
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if (fd < 0) {
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if (errno == EEXIST) {
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if ((fd = open(path, O_RDONLY)) < 0)
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return -errno;
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return fd;
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}
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return -errno;
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}
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if (close(fd) < 0)
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return -errno;
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/* mask off all signals, store old signal mask */
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if (sigfillset(&intmask) < 0)
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return -errno;
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if ((rc = sigprocmask(SIG_BLOCK, &intmask, &oldmask)) != 0)
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return -rc;
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/* create a new network namespace */
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if (unshare(CLONE_NEWNET) < 0) {
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ret = -errno;
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goto restore_sigmask;
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}
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if (mount("/proc/self/ns/net", path, "none", MS_BIND, NULL) < 0)
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ret = -errno;
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/* switch back to default namespace */
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if (setns(default_nsfd, CLONE_NEWNET) < 0)
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return -errno;
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restore_sigmask:
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/* restore process mask */
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if ((rc = sigprocmask(SIG_SETMASK, &oldmask, NULL)) != 0)
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return -rc;
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/* might have been set above in case mount fails */
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if (ret < 0)
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return ret;
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/* finally, open the created namespace file descriptor from default ns */
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if ((fd = open(path, O_RDONLY)) < 0)
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return -errno;
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return fd;
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}
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#endif
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