kernel/nsproxy.c

   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/module.h>
  17 #include <linux/version.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
  26 static struct kmem_cache *nsproxy_cachep;
  27
  28 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
  29
  30 /*
  31  * creates a copy of "orig" with refcount 1.
  32  */
  33 static inline struct nsproxy *clone_nsproxy(struct nsproxy *orig)
  34 {
  35         struct nsproxy *ns;
  36
  37         ns = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
  38         if (ns) {
  39                 memcpy(ns, orig, sizeof(struct nsproxy));
  40                 atomic_set(&ns->count, 1);
  41         }
  42         return ns;
  43 }
  44
  45 /*
  46  * Create new nsproxy and all of its the associated namespaces.
  47  * Return the newly created nsproxy.  Do not attach this to the task,
  48  * leave it to the caller to do proper locking and attach it to task.
  49  */
  50 static struct nsproxy *create_new_namespaces(unsigned long flags,
  51                         struct task_struct *tsk, struct fs_struct *new_fs)
  52 {
  53         struct nsproxy *new_nsp;
  54         int err;
  55
  56         new_nsp = clone_nsproxy(tsk->nsproxy);
  57         if (!new_nsp)
  58                 return ERR_PTR(-ENOMEM);
  59
  60         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
  61         if (IS_ERR(new_nsp->mnt_ns)) {
  62                 err = PTR_ERR(new_nsp->mnt_ns);
  63                 goto out_ns;
  64         }
  65
  66         new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
  67         if (IS_ERR(new_nsp->uts_ns)) {
  68                 err = PTR_ERR(new_nsp->uts_ns);
  69                 goto out_uts;
  70         }
  71
  72         new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
  73         if (IS_ERR(new_nsp->ipc_ns)) {
  74                 err = PTR_ERR(new_nsp->ipc_ns);
  75                 goto out_ipc;
  76         }
  77
  78         new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
  79         if (IS_ERR(new_nsp->pid_ns)) {
  80                 err = PTR_ERR(new_nsp->pid_ns);
  81                 goto out_pid;
  82         }
  83
  84         new_nsp->user_ns = copy_user_ns(flags, tsk->nsproxy->user_ns);
  85         if (IS_ERR(new_nsp->user_ns)) {
  86                 err = PTR_ERR(new_nsp->user_ns);
  87                 goto out_user;
  88         }
  89
  90         new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns);
  91         if (IS_ERR(new_nsp->net_ns)) {
  92                 err = PTR_ERR(new_nsp->net_ns);
  93                 goto out_net;
  94         }
  95
  96         return new_nsp;
  97
  98 out_net:
  99         if (new_nsp->user_ns)
 100                 put_user_ns(new_nsp->user_ns);
 101 out_user:
 102         if (new_nsp->pid_ns)
 103                 put_pid_ns(new_nsp->pid_ns);
 104 out_pid:
 105         if (new_nsp->ipc_ns)
 106                 put_ipc_ns(new_nsp->ipc_ns);
 107 out_ipc:
 108         if (new_nsp->uts_ns)
 109                 put_uts_ns(new_nsp->uts_ns);
 110 out_uts:
 111         if (new_nsp->mnt_ns)
 112                 put_mnt_ns(new_nsp->mnt_ns);
 113 out_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  */
 122 int 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_NEWUSER | 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         err = ns_cgroup_clone(tsk);
 161         if (err) {
 162                 put_nsproxy(new_ns);
 163                 goto out;
 164         }
 165
 166         tsk->nsproxy = new_ns;
 167
 168 out:
 169         put_nsproxy(old_ns);
 170         return err;
 171 }
 172
 173 void free_nsproxy(struct nsproxy *ns)
 174 {
 175         if (ns->mnt_ns)
 176                 put_mnt_ns(ns->mnt_ns);
 177         if (ns->uts_ns)
 178                 put_uts_ns(ns->uts_ns);
 179         if (ns->ipc_ns)
 180                 put_ipc_ns(ns->ipc_ns);
 181         if (ns->pid_ns)
 182                 put_pid_ns(ns->pid_ns);
 183         if (ns->user_ns)
 184                 put_user_ns(ns->user_ns);
 185         put_net(ns->net_ns);
 186         kmem_cache_free(nsproxy_cachep, ns);
 187 }
 188
 189 /*
 190  * Called from unshare. Unshare all the namespaces part of nsproxy.
 191  * On success, returns the new nsproxy.
 192  */
 193 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 194                 struct nsproxy **new_nsp, struct fs_struct *new_fs)
 195 {
 196         int err = 0;
 197
 198         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 199                                CLONE_NEWUSER | CLONE_NEWNET)))
 200                 return 0;
 201
 202         if (!capable(CAP_SYS_ADMIN))
 203                 return -EPERM;
 204
 205         *new_nsp = create_new_namespaces(unshare_flags, current,
 206                                 new_fs ? new_fs : current->fs);
 207         if (IS_ERR(*new_nsp)) {
 208                 err = PTR_ERR(*new_nsp);
 209                 goto out;
 210         }
 211
 212         err = ns_cgroup_clone(current);
 213         if (err)
 214                 put_nsproxy(*new_nsp);
 215
 216 out:
 217         return err;
 218 }
 219
 220 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
 221 {
 222         struct nsproxy *ns;
 223
 224         might_sleep();
 225
 226         ns = p->nsproxy;
 227
 228         rcu_assign_pointer(p->nsproxy, new);
 229
 230         if (ns && atomic_dec_and_test(&ns->count)) {
 231                 /*
 232                  * wait for others to get what they want from this nsproxy.
 233                  *
 234                  * cannot release this nsproxy via the call_rcu() since
 235                  * put_mnt_ns() will want to sleep
 236                  */
 237                 synchronize_rcu();
 238                 free_nsproxy(ns);
 239         }
 240 }
 241
 242 void exit_task_namespaces(struct task_struct *p)
 243 {
 244         switch_task_namespaces(p, NULL);
 245 }
 246
 247 static int __init nsproxy_cache_init(void)
 248 {
 249         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
 250         return 0;
 251 }
 252
 253 module_init(nsproxy_cache_init);