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![Aditya Kali](/assets/img/avatar_default.png)
Introduce the ability to create new cgroup namespace. The newly created cgroup namespace remembers the cgroup of the process at the point of creation of the cgroup namespace (referred as cgroupns-root). The main purpose of cgroup namespace is to virtualize the contents of /proc/self/cgroup file. Processes inside a cgroup namespace are only able to see paths relative to their namespace root (unless they are moved outside of their cgroupns-root, at which point they will see a relative path from their cgroupns-root). For a correctly setup container this enables container-tools (like libcontainer, lxc, lmctfy, etc.) to create completely virtualized containers without leaking system level cgroup hierarchy to the task. This patch only implements the 'unshare' part of the cgroupns. Signed-off-by: Aditya Kali <adityakali@google.com> Signed-off-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Tejun Heo <tj@kernel.org>
274 lines
6.4 KiB
C
274 lines
6.4 KiB
C
/*
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* Copyright (C) 2006 IBM Corporation
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*
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* Author: Serge Hallyn <serue@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*
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* Jun 2006 - namespaces support
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* OpenVZ, SWsoft Inc.
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* Pavel Emelianov <xemul@openvz.org>
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*/
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#include <linux/slab.h>
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#include <linux/export.h>
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#include <linux/nsproxy.h>
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#include <linux/init_task.h>
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#include <linux/mnt_namespace.h>
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#include <linux/utsname.h>
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#include <linux/pid_namespace.h>
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#include <net/net_namespace.h>
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#include <linux/ipc_namespace.h>
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#include <linux/proc_ns.h>
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#include <linux/file.h>
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#include <linux/syscalls.h>
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#include <linux/cgroup.h>
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static struct kmem_cache *nsproxy_cachep;
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struct nsproxy init_nsproxy = {
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.count = ATOMIC_INIT(1),
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.uts_ns = &init_uts_ns,
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#if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
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.ipc_ns = &init_ipc_ns,
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#endif
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.mnt_ns = NULL,
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.pid_ns_for_children = &init_pid_ns,
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#ifdef CONFIG_NET
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.net_ns = &init_net,
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#endif
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#ifdef CONFIG_CGROUPS
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.cgroup_ns = &init_cgroup_ns,
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#endif
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};
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static inline struct nsproxy *create_nsproxy(void)
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{
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struct nsproxy *nsproxy;
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nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
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if (nsproxy)
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atomic_set(&nsproxy->count, 1);
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return nsproxy;
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}
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/*
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* Create new nsproxy and all of its the associated namespaces.
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* Return the newly created nsproxy. Do not attach this to the task,
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* leave it to the caller to do proper locking and attach it to task.
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*/
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static struct nsproxy *create_new_namespaces(unsigned long flags,
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struct task_struct *tsk, struct user_namespace *user_ns,
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struct fs_struct *new_fs)
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{
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struct nsproxy *new_nsp;
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int err;
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new_nsp = create_nsproxy();
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if (!new_nsp)
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return ERR_PTR(-ENOMEM);
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new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
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if (IS_ERR(new_nsp->mnt_ns)) {
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err = PTR_ERR(new_nsp->mnt_ns);
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goto out_ns;
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}
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new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
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if (IS_ERR(new_nsp->uts_ns)) {
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err = PTR_ERR(new_nsp->uts_ns);
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goto out_uts;
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}
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new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
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if (IS_ERR(new_nsp->ipc_ns)) {
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err = PTR_ERR(new_nsp->ipc_ns);
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goto out_ipc;
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}
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new_nsp->pid_ns_for_children =
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copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);
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if (IS_ERR(new_nsp->pid_ns_for_children)) {
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err = PTR_ERR(new_nsp->pid_ns_for_children);
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goto out_pid;
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}
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new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns,
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tsk->nsproxy->cgroup_ns);
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if (IS_ERR(new_nsp->cgroup_ns)) {
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err = PTR_ERR(new_nsp->cgroup_ns);
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goto out_cgroup;
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}
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new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
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if (IS_ERR(new_nsp->net_ns)) {
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err = PTR_ERR(new_nsp->net_ns);
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goto out_net;
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}
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return new_nsp;
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out_net:
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put_cgroup_ns(new_nsp->cgroup_ns);
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out_cgroup:
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if (new_nsp->pid_ns_for_children)
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put_pid_ns(new_nsp->pid_ns_for_children);
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out_pid:
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if (new_nsp->ipc_ns)
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put_ipc_ns(new_nsp->ipc_ns);
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out_ipc:
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if (new_nsp->uts_ns)
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put_uts_ns(new_nsp->uts_ns);
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out_uts:
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if (new_nsp->mnt_ns)
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put_mnt_ns(new_nsp->mnt_ns);
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out_ns:
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kmem_cache_free(nsproxy_cachep, new_nsp);
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return ERR_PTR(err);
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}
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/*
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* called from clone. This now handles copy for nsproxy and all
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* namespaces therein.
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*/
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int copy_namespaces(unsigned long flags, struct task_struct *tsk)
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{
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struct nsproxy *old_ns = tsk->nsproxy;
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struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
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struct nsproxy *new_ns;
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if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
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CLONE_NEWPID | CLONE_NEWNET |
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CLONE_NEWCGROUP)))) {
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get_nsproxy(old_ns);
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return 0;
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}
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if (!ns_capable(user_ns, CAP_SYS_ADMIN))
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return -EPERM;
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/*
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* CLONE_NEWIPC must detach from the undolist: after switching
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* to a new ipc namespace, the semaphore arrays from the old
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* namespace are unreachable. In clone parlance, CLONE_SYSVSEM
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* means share undolist with parent, so we must forbid using
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* it along with CLONE_NEWIPC.
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*/
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if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
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(CLONE_NEWIPC | CLONE_SYSVSEM))
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return -EINVAL;
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new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
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if (IS_ERR(new_ns))
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return PTR_ERR(new_ns);
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tsk->nsproxy = new_ns;
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return 0;
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}
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void free_nsproxy(struct nsproxy *ns)
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{
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if (ns->mnt_ns)
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put_mnt_ns(ns->mnt_ns);
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if (ns->uts_ns)
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put_uts_ns(ns->uts_ns);
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if (ns->ipc_ns)
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put_ipc_ns(ns->ipc_ns);
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if (ns->pid_ns_for_children)
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put_pid_ns(ns->pid_ns_for_children);
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put_cgroup_ns(ns->cgroup_ns);
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put_net(ns->net_ns);
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kmem_cache_free(nsproxy_cachep, ns);
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}
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/*
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* Called from unshare. Unshare all the namespaces part of nsproxy.
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* On success, returns the new nsproxy.
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*/
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int unshare_nsproxy_namespaces(unsigned long unshare_flags,
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struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
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{
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struct user_namespace *user_ns;
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int err = 0;
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if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
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CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP)))
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return 0;
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user_ns = new_cred ? new_cred->user_ns : current_user_ns();
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if (!ns_capable(user_ns, CAP_SYS_ADMIN))
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return -EPERM;
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*new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
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new_fs ? new_fs : current->fs);
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if (IS_ERR(*new_nsp)) {
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err = PTR_ERR(*new_nsp);
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goto out;
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}
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out:
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return err;
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}
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void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
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{
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struct nsproxy *ns;
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might_sleep();
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task_lock(p);
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ns = p->nsproxy;
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p->nsproxy = new;
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task_unlock(p);
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if (ns && atomic_dec_and_test(&ns->count))
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free_nsproxy(ns);
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}
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void exit_task_namespaces(struct task_struct *p)
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{
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switch_task_namespaces(p, NULL);
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}
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SYSCALL_DEFINE2(setns, int, fd, int, nstype)
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{
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struct task_struct *tsk = current;
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struct nsproxy *new_nsproxy;
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struct file *file;
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struct ns_common *ns;
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int err;
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file = proc_ns_fget(fd);
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if (IS_ERR(file))
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return PTR_ERR(file);
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err = -EINVAL;
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ns = get_proc_ns(file_inode(file));
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if (nstype && (ns->ops->type != nstype))
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goto out;
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new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
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if (IS_ERR(new_nsproxy)) {
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err = PTR_ERR(new_nsproxy);
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goto out;
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}
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err = ns->ops->install(new_nsproxy, ns);
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if (err) {
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free_nsproxy(new_nsproxy);
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goto out;
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}
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switch_task_namespaces(tsk, new_nsproxy);
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out:
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fput(file);
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return err;
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}
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int __init nsproxy_cache_init(void)
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{
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nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
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return 0;
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}
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