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![Christian Brauner](/assets/img/avatar_default.png)
So far setns() was missing time namespace support. This was partially due to it simply not being implemented but also because vdso_join_timens() could still fail which made switching to multiple namespaces atomically problematic. This is now fixed so support CLONE_NEWTIME with setns() Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Andrei Vagin <avagin@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Serge Hallyn <serge@hallyn.com> Cc: Dmitry Safonov <dima@arista.com> Link: https://lore.kernel.org/r/20200706154912.3248030-4-christian.brauner@ubuntu.com
578 lines
13 KiB
C
578 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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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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* 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/time_namespace.h>
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#include <linux/fs_struct.h>
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#include <linux/proc_fs.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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#include <linux/perf_event.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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#ifdef CONFIG_TIME_NS
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.time_ns = &init_time_ns,
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.time_ns_for_children = &init_time_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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new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns,
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tsk->nsproxy->time_ns_for_children);
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if (IS_ERR(new_nsp->time_ns_for_children)) {
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err = PTR_ERR(new_nsp->time_ns_for_children);
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goto out_time;
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}
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new_nsp->time_ns = get_time_ns(tsk->nsproxy->time_ns);
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return new_nsp;
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out_time:
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put_net(new_nsp->net_ns);
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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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int ret;
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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 | CLONE_NEWTIME)))) {
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if (likely(old_ns->time_ns_for_children == old_ns->time_ns)) {
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get_nsproxy(old_ns);
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return 0;
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}
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} else 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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ret = timens_on_fork(new_ns, tsk);
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if (ret) {
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free_nsproxy(new_ns);
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return ret;
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}
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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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if (ns->time_ns)
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put_time_ns(ns->time_ns);
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if (ns->time_ns_for_children)
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put_time_ns(ns->time_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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CLONE_NEWTIME)))
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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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static int check_setns_flags(unsigned long flags)
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{
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if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
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CLONE_NEWNET | CLONE_NEWTIME | CLONE_NEWUSER |
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CLONE_NEWPID | CLONE_NEWCGROUP)))
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return -EINVAL;
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#ifndef CONFIG_USER_NS
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if (flags & CLONE_NEWUSER)
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return -EINVAL;
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#endif
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#ifndef CONFIG_PID_NS
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if (flags & CLONE_NEWPID)
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return -EINVAL;
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#endif
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#ifndef CONFIG_UTS_NS
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if (flags & CLONE_NEWUTS)
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return -EINVAL;
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#endif
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#ifndef CONFIG_IPC_NS
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if (flags & CLONE_NEWIPC)
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return -EINVAL;
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#endif
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#ifndef CONFIG_CGROUPS
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if (flags & CLONE_NEWCGROUP)
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return -EINVAL;
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#endif
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#ifndef CONFIG_NET_NS
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if (flags & CLONE_NEWNET)
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return -EINVAL;
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#endif
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#ifndef CONFIG_TIME_NS
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if (flags & CLONE_NEWTIME)
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return -EINVAL;
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#endif
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return 0;
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}
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static void put_nsset(struct nsset *nsset)
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{
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unsigned flags = nsset->flags;
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if (flags & CLONE_NEWUSER)
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put_cred(nsset_cred(nsset));
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/*
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* We only created a temporary copy if we attached to more than just
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* the mount namespace.
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*/
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if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS))
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free_fs_struct(nsset->fs);
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if (nsset->nsproxy)
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free_nsproxy(nsset->nsproxy);
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}
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static int prepare_nsset(unsigned flags, struct nsset *nsset)
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{
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struct task_struct *me = current;
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nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs);
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if (IS_ERR(nsset->nsproxy))
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return PTR_ERR(nsset->nsproxy);
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if (flags & CLONE_NEWUSER)
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nsset->cred = prepare_creds();
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else
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nsset->cred = current_cred();
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if (!nsset->cred)
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goto out;
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/* Only create a temporary copy of fs_struct if we really need to. */
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if (flags == CLONE_NEWNS) {
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nsset->fs = me->fs;
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} else if (flags & CLONE_NEWNS) {
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nsset->fs = copy_fs_struct(me->fs);
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if (!nsset->fs)
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goto out;
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}
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nsset->flags = flags;
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return 0;
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out:
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put_nsset(nsset);
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return -ENOMEM;
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}
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static inline int validate_ns(struct nsset *nsset, struct ns_common *ns)
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{
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return ns->ops->install(nsset, ns);
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}
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/*
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* This is the inverse operation to unshare().
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* Ordering is equivalent to the standard ordering used everywhere else
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* during unshare and process creation. The switch to the new set of
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* namespaces occurs at the point of no return after installation of
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* all requested namespaces was successful in commit_nsset().
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*/
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static int validate_nsset(struct nsset *nsset, struct pid *pid)
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{
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int ret = 0;
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unsigned flags = nsset->flags;
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struct user_namespace *user_ns = NULL;
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struct pid_namespace *pid_ns = NULL;
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struct nsproxy *nsp;
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struct task_struct *tsk;
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/* Take a "snapshot" of the target task's namespaces. */
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rcu_read_lock();
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tsk = pid_task(pid, PIDTYPE_PID);
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if (!tsk) {
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rcu_read_unlock();
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return -ESRCH;
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}
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if (!ptrace_may_access(tsk, PTRACE_MODE_READ_REALCREDS)) {
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rcu_read_unlock();
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return -EPERM;
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}
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task_lock(tsk);
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nsp = tsk->nsproxy;
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if (nsp)
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get_nsproxy(nsp);
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task_unlock(tsk);
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if (!nsp) {
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rcu_read_unlock();
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return -ESRCH;
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}
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#ifdef CONFIG_PID_NS
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if (flags & CLONE_NEWPID) {
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pid_ns = task_active_pid_ns(tsk);
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if (unlikely(!pid_ns)) {
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rcu_read_unlock();
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ret = -ESRCH;
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goto out;
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}
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get_pid_ns(pid_ns);
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}
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#endif
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#ifdef CONFIG_USER_NS
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if (flags & CLONE_NEWUSER)
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user_ns = get_user_ns(__task_cred(tsk)->user_ns);
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#endif
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rcu_read_unlock();
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/*
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* Install requested namespaces. The caller will have
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* verified earlier that the requested namespaces are
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* supported on this kernel. We don't report errors here
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* if a namespace is requested that isn't supported.
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*/
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#ifdef CONFIG_USER_NS
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if (flags & CLONE_NEWUSER) {
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ret = validate_ns(nsset, &user_ns->ns);
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if (ret)
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goto out;
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}
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#endif
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if (flags & CLONE_NEWNS) {
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ret = validate_ns(nsset, from_mnt_ns(nsp->mnt_ns));
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if (ret)
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goto out;
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}
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#ifdef CONFIG_UTS_NS
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if (flags & CLONE_NEWUTS) {
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ret = validate_ns(nsset, &nsp->uts_ns->ns);
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if (ret)
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goto out;
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}
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#endif
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#ifdef CONFIG_IPC_NS
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if (flags & CLONE_NEWIPC) {
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ret = validate_ns(nsset, &nsp->ipc_ns->ns);
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if (ret)
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goto out;
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}
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#endif
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#ifdef CONFIG_PID_NS
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if (flags & CLONE_NEWPID) {
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ret = validate_ns(nsset, &pid_ns->ns);
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if (ret)
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goto out;
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}
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#endif
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#ifdef CONFIG_CGROUPS
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if (flags & CLONE_NEWCGROUP) {
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ret = validate_ns(nsset, &nsp->cgroup_ns->ns);
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if (ret)
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goto out;
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}
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#endif
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#ifdef CONFIG_NET_NS
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if (flags & CLONE_NEWNET) {
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ret = validate_ns(nsset, &nsp->net_ns->ns);
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if (ret)
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goto out;
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}
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#endif
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#ifdef CONFIG_TIME_NS
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if (flags & CLONE_NEWTIME) {
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ret = validate_ns(nsset, &nsp->time_ns->ns);
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if (ret)
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goto out;
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}
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#endif
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out:
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if (pid_ns)
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put_pid_ns(pid_ns);
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if (nsp)
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put_nsproxy(nsp);
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put_user_ns(user_ns);
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return ret;
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}
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/*
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* This is the point of no return. There are just a few namespaces
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* that do some actual work here and it's sufficiently minimal that
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* a separate ns_common operation seems unnecessary for now.
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* Unshare is doing the same thing. If we'll end up needing to do
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* more in a given namespace or a helper here is ultimately not
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* exported anymore a simple commit handler for each namespace
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* should be added to ns_common.
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*/
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static void commit_nsset(struct nsset *nsset)
|
|
{
|
|
unsigned flags = nsset->flags;
|
|
struct task_struct *me = current;
|
|
|
|
#ifdef CONFIG_USER_NS
|
|
if (flags & CLONE_NEWUSER) {
|
|
/* transfer ownership */
|
|
commit_creds(nsset_cred(nsset));
|
|
nsset->cred = NULL;
|
|
}
|
|
#endif
|
|
|
|
/* We only need to commit if we have used a temporary fs_struct. */
|
|
if ((flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) {
|
|
set_fs_root(me->fs, &nsset->fs->root);
|
|
set_fs_pwd(me->fs, &nsset->fs->pwd);
|
|
}
|
|
|
|
#ifdef CONFIG_IPC_NS
|
|
if (flags & CLONE_NEWIPC)
|
|
exit_sem(me);
|
|
#endif
|
|
|
|
#ifdef CONFIG_TIME_NS
|
|
if (flags & CLONE_NEWTIME)
|
|
timens_commit(me, nsset->nsproxy->time_ns);
|
|
#endif
|
|
|
|
/* transfer ownership */
|
|
switch_task_namespaces(me, nsset->nsproxy);
|
|
nsset->nsproxy = NULL;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(setns, int, fd, int, flags)
|
|
{
|
|
struct file *file;
|
|
struct ns_common *ns = NULL;
|
|
struct nsset nsset = {};
|
|
int err = 0;
|
|
|
|
file = fget(fd);
|
|
if (!file)
|
|
return -EBADF;
|
|
|
|
if (proc_ns_file(file)) {
|
|
ns = get_proc_ns(file_inode(file));
|
|
if (flags && (ns->ops->type != flags))
|
|
err = -EINVAL;
|
|
flags = ns->ops->type;
|
|
} else if (!IS_ERR(pidfd_pid(file))) {
|
|
err = check_setns_flags(flags);
|
|
} else {
|
|
err = -EINVAL;
|
|
}
|
|
if (err)
|
|
goto out;
|
|
|
|
err = prepare_nsset(flags, &nsset);
|
|
if (err)
|
|
goto out;
|
|
|
|
if (proc_ns_file(file))
|
|
err = validate_ns(&nsset, ns);
|
|
else
|
|
err = validate_nsset(&nsset, file->private_data);
|
|
if (!err) {
|
|
commit_nsset(&nsset);
|
|
perf_event_namespaces(current);
|
|
}
|
|
put_nsset(&nsset);
|
|
out:
|
|
fput(file);
|
|
return err;
|
|
}
|
|
|
|
int __init nsproxy_cache_init(void)
|
|
{
|
|
nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
|
|
return 0;
|
|
}
|