linux/kernel/nsproxy.c
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   1/*
   2 *  Copyright (C) 2006 IBM Corporation
   3 *
   4 *  Author: Serge Hallyn <serue@us.ibm.com>
   5 *
   6 *  This program is free software; you can redistribute it and/or
   7 *  modify it under the terms of the GNU General Public License as
   8 *  published by the Free Software Foundation, version 2 of the
   9 *  License.
  10 *
  11 *  Jun 2006 - namespaces support
  12 *             OpenVZ, SWsoft Inc.
  13 *             Pavel Emelianov <xemul@openvz.org>
  14 */
  15
  16#include <linux/slab.h>
  17#include <linux/module.h>
  18#include <linux/nsproxy.h>
  19#include <linux/init_task.h>
  20#include <linux/mnt_namespace.h>
  21#include <linux/utsname.h>
  22#include <linux/pid_namespace.h>
  23#include <net/net_namespace.h>
  24#include <linux/ipc_namespace.h>
  25#include <linux/proc_fs.h>
  26#include <linux/file.h>
  27#include <linux/syscalls.h>
  28
  29static struct kmem_cache *nsproxy_cachep;
  30
  31struct nsproxy init_nsproxy = {
  32        .count  = ATOMIC_INIT(1),
  33        .uts_ns = &init_uts_ns,
  34#if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
  35        .ipc_ns = &init_ipc_ns,
  36#endif
  37        .mnt_ns = NULL,
  38        .pid_ns = &init_pid_ns,
  39#ifdef CONFIG_NET
  40        .net_ns = &init_net,
  41#endif
  42};
  43
  44static inline struct nsproxy *create_nsproxy(void)
  45{
  46        struct nsproxy *nsproxy;
  47
  48        nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
  49        if (nsproxy)
  50                atomic_set(&nsproxy->count, 1);
  51        return nsproxy;
  52}
  53
  54/*
  55 * Create new nsproxy and all of its the associated namespaces.
  56 * Return the newly created nsproxy.  Do not attach this to the task,
  57 * leave it to the caller to do proper locking and attach it to task.
  58 */
  59static struct nsproxy *create_new_namespaces(unsigned long flags,
  60                        struct task_struct *tsk, struct fs_struct *new_fs)
  61{
  62        struct nsproxy *new_nsp;
  63        int err;
  64
  65        new_nsp = create_nsproxy();
  66        if (!new_nsp)
  67                return ERR_PTR(-ENOMEM);
  68
  69        new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
  70        if (IS_ERR(new_nsp->mnt_ns)) {
  71                err = PTR_ERR(new_nsp->mnt_ns);
  72                goto out_ns;
  73        }
  74
  75        new_nsp->uts_ns = copy_utsname(flags, tsk);
  76        if (IS_ERR(new_nsp->uts_ns)) {
  77                err = PTR_ERR(new_nsp->uts_ns);
  78                goto out_uts;
  79        }
  80
  81        new_nsp->ipc_ns = copy_ipcs(flags, tsk);
  82        if (IS_ERR(new_nsp->ipc_ns)) {
  83                err = PTR_ERR(new_nsp->ipc_ns);
  84                goto out_ipc;
  85        }
  86
  87        new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
  88        if (IS_ERR(new_nsp->pid_ns)) {
  89                err = PTR_ERR(new_nsp->pid_ns);
  90                goto out_pid;
  91        }
  92
  93        new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns);
  94        if (IS_ERR(new_nsp->net_ns)) {
  95                err = PTR_ERR(new_nsp->net_ns);
  96                goto out_net;
  97        }
  98
  99        return new_nsp;
 100
 101out_net:
 102        if (new_nsp->pid_ns)
 103                put_pid_ns(new_nsp->pid_ns);
 104out_pid:
 105        if (new_nsp->ipc_ns)
 106                put_ipc_ns(new_nsp->ipc_ns);
 107out_ipc:
 108        if (new_nsp->uts_ns)
 109                put_uts_ns(new_nsp->uts_ns);
 110out_uts:
 111        if (new_nsp->mnt_ns)
 112                put_mnt_ns(new_nsp->mnt_ns);
 113out_ns:
 114        kmem_cache_free(nsproxy_cachep, new_nsp);
 115        return ERR_PTR(err);
 116}
 117
 118/*
 119 * called from clone.  This now handles copy for nsproxy and all
 120 * namespaces therein.
 121 */
 122int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 123{
 124        struct nsproxy *old_ns = tsk->nsproxy;
 125        struct nsproxy *new_ns;
 126        int err = 0;
 127
 128        if (!old_ns)
 129                return 0;
 130
 131        get_nsproxy(old_ns);
 132
 133        if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 134                                CLONE_NEWPID | CLONE_NEWNET)))
 135                return 0;
 136
 137        if (!capable(CAP_SYS_ADMIN)) {
 138                err = -EPERM;
 139                goto out;
 140        }
 141
 142        /*
 143         * CLONE_NEWIPC must detach from the undolist: after switching
 144         * to a new ipc namespace, the semaphore arrays from the old
 145         * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
 146         * means share undolist with parent, so we must forbid using
 147         * it along with CLONE_NEWIPC.
 148         */
 149        if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
 150                err = -EINVAL;
 151                goto out;
 152        }
 153
 154        new_ns = create_new_namespaces(flags, tsk, tsk->fs);
 155        if (IS_ERR(new_ns)) {
 156                err = PTR_ERR(new_ns);
 157                goto out;
 158        }
 159
 160        tsk->nsproxy = new_ns;
 161
 162out:
 163        put_nsproxy(old_ns);
 164        return err;
 165}
 166
 167void free_nsproxy(struct nsproxy *ns)
 168{
 169        if (ns->mnt_ns)
 170                put_mnt_ns(ns->mnt_ns);
 171        if (ns->uts_ns)
 172                put_uts_ns(ns->uts_ns);
 173        if (ns->ipc_ns)
 174                put_ipc_ns(ns->ipc_ns);
 175        if (ns->pid_ns)
 176                put_pid_ns(ns->pid_ns);
 177        put_net(ns->net_ns);
 178        kmem_cache_free(nsproxy_cachep, ns);
 179}
 180
 181/*
 182 * Called from unshare. Unshare all the namespaces part of nsproxy.
 183 * On success, returns the new nsproxy.
 184 */
 185int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 186                struct nsproxy **new_nsp, struct fs_struct *new_fs)
 187{
 188        int err = 0;
 189
 190        if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 191                               CLONE_NEWNET)))
 192                return 0;
 193
 194        if (!capable(CAP_SYS_ADMIN))
 195                return -EPERM;
 196
 197        *new_nsp = create_new_namespaces(unshare_flags, current,
 198                                new_fs ? new_fs : current->fs);
 199        if (IS_ERR(*new_nsp)) {
 200                err = PTR_ERR(*new_nsp);
 201                goto out;
 202        }
 203
 204out:
 205        return err;
 206}
 207
 208void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
 209{
 210        struct nsproxy *ns;
 211
 212        might_sleep();
 213
 214        ns = p->nsproxy;
 215
 216        rcu_assign_pointer(p->nsproxy, new);
 217
 218        if (ns && atomic_dec_and_test(&ns->count)) {
 219                /*
 220                 * wait for others to get what they want from this nsproxy.
 221                 *
 222                 * cannot release this nsproxy via the call_rcu() since
 223                 * put_mnt_ns() will want to sleep
 224                 */
 225                synchronize_rcu();
 226                free_nsproxy(ns);
 227        }
 228}
 229
 230void exit_task_namespaces(struct task_struct *p)
 231{
 232        switch_task_namespaces(p, NULL);
 233}
 234
 235SYSCALL_DEFINE2(setns, int, fd, int, nstype)
 236{
 237        const struct proc_ns_operations *ops;
 238        struct task_struct *tsk = current;
 239        struct nsproxy *new_nsproxy;
 240        struct proc_inode *ei;
 241        struct file *file;
 242        int err;
 243
 244        if (!capable(CAP_SYS_ADMIN))
 245                return -EPERM;
 246
 247        file = proc_ns_fget(fd);
 248        if (IS_ERR(file))
 249                return PTR_ERR(file);
 250
 251        err = -EINVAL;
 252        ei = PROC_I(file->f_dentry->d_inode);
 253        ops = ei->ns_ops;
 254        if (nstype && (ops->type != nstype))
 255                goto out;
 256
 257        new_nsproxy = create_new_namespaces(0, tsk, tsk->fs);
 258        if (IS_ERR(new_nsproxy)) {
 259                err = PTR_ERR(new_nsproxy);
 260                goto out;
 261        }
 262
 263        err = ops->install(new_nsproxy, ei->ns);
 264        if (err) {
 265                free_nsproxy(new_nsproxy);
 266                goto out;
 267        }
 268        switch_task_namespaces(tsk, new_nsproxy);
 269out:
 270        fput(file);
 271        return err;
 272}
 273
 274int __init nsproxy_cache_init(void)
 275{
 276        nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
 277        return 0;
 278}
 279
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