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/nsproxy.h>
  18 #include <linux/init_task.h>
  19 #include <linux/mnt_namespace.h>
  20 #include <linux/utsname.h>
  21 #include <linux/pid_namespace.h>
  22 #include <net/net_namespace.h>
  23 #include <linux/ipc_namespace.h>
  24
  25 static struct kmem_cache *nsproxy_cachep;
  26
  27 struct nsproxy init_nsproxy = {
  28         .count  = ATOMIC_INIT(1),
  29         .uts_ns = &init_uts_ns,
  30 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
  31         .ipc_ns = &init_ipc_ns,
  32 #endif
  33         .mnt_ns = NULL,
  34         .pid_ns = &init_pid_ns,
  35 #ifdef CONFIG_NET
  36         .net_ns = &init_net,
  37 #endif
  38 };
  39
  40 static inline struct nsproxy *create_nsproxy(void)
  41 {
  42         struct nsproxy *nsproxy;
  43
  44         nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
  45         if (nsproxy)
  46                 atomic_set(&nsproxy->count, 1);
  47         return nsproxy;
  48 }
  49
  50 /*
  51  * Create new nsproxy and all of its the associated namespaces.
  52  * Return the newly created nsproxy.  Do not attach this to the task,
  53  * leave it to the caller to do proper locking and attach it to task.
  54  */
  55 static struct nsproxy *create_new_namespaces(unsigned long flags,
  56                         struct task_struct *tsk, struct fs_struct *new_fs)
  57 {
  58         struct nsproxy *new_nsp;
  59         int err;
  60
  61         new_nsp = create_nsproxy();
  62         if (!new_nsp)
  63                 return ERR_PTR(-ENOMEM);
  64
  65         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
  66         if (IS_ERR(new_nsp->mnt_ns)) {
  67                 err = PTR_ERR(new_nsp->mnt_ns);
  68                 goto out_ns;
  69         }
  70
  71         new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
  72         if (IS_ERR(new_nsp->uts_ns)) {
  73                 err = PTR_ERR(new_nsp->uts_ns);
  74                 goto out_uts;
  75         }
  76
  77         new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
  78         if (IS_ERR(new_nsp->ipc_ns)) {
  79                 err = PTR_ERR(new_nsp->ipc_ns);
  80                 goto out_ipc;
  81         }
  82
  83         new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
  84         if (IS_ERR(new_nsp->pid_ns)) {
  85                 err = PTR_ERR(new_nsp->pid_ns);
  86                 goto out_pid;
  87         }
  88
  89         new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns);
  90         if (IS_ERR(new_nsp->net_ns)) {
  91                 err = PTR_ERR(new_nsp->net_ns);
  92                 goto out_net;
  93         }
  94
  95         return new_nsp;
  96
  97 out_net:
  98         if (new_nsp->pid_ns)
  99                 put_pid_ns(new_nsp->pid_ns);
 100 out_pid:
 101         if (new_nsp->ipc_ns)
 102                 put_ipc_ns(new_nsp->ipc_ns);
 103 out_ipc:
 104         if (new_nsp->uts_ns)
 105                 put_uts_ns(new_nsp->uts_ns);
 106 out_uts:
 107         if (new_nsp->mnt_ns)
 108                 put_mnt_ns(new_nsp->mnt_ns);
 109 out_ns:
 110         kmem_cache_free(nsproxy_cachep, new_nsp);
 111         return ERR_PTR(err);
 112 }
 113
 114 /*
 115  * called from clone.  This now handles copy for nsproxy and all
 116  * namespaces therein.
 117  */
 118 int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 119 {
 120         struct nsproxy *old_ns = tsk->nsproxy;
 121         struct nsproxy *new_ns;
 122         int err = 0;
 123
 124         if (!old_ns)
 125                 return 0;
 126
 127         get_nsproxy(old_ns);
 128
 129         if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 130                                 CLONE_NEWPID | CLONE_NEWNET)))
 131                 return 0;
 132
 133         if (!capable(CAP_SYS_ADMIN)) {
 134                 err = -EPERM;
 135                 goto out;
 136         }
 137
 138         /*
 139          * CLONE_NEWIPC must detach from the undolist: after switching
 140          * to a new ipc namespace, the semaphore arrays from the old
 141          * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
 142          * means share undolist with parent, so we must forbid using
 143          * it along with CLONE_NEWIPC.
 144          */
 145         if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
 146                 err = -EINVAL;
 147                 goto out;
 148         }
 149
 150         new_ns = create_new_namespaces(flags, tsk, tsk->fs);
 151         if (IS_ERR(new_ns)) {
 152                 err = PTR_ERR(new_ns);
 153                 goto out;
 154         }
 155
 156         tsk->nsproxy = new_ns;
 157
 158 out:
 159         put_nsproxy(old_ns);
 160         return err;
 161 }
 162
 163 void free_nsproxy(struct nsproxy *ns)
 164 {
 165         if (ns->mnt_ns)
 166                 put_mnt_ns(ns->mnt_ns);
 167         if (ns->uts_ns)
 168                 put_uts_ns(ns->uts_ns);
 169         if (ns->ipc_ns)
 170                 put_ipc_ns(ns->ipc_ns);
 171         if (ns->pid_ns)
 172                 put_pid_ns(ns->pid_ns);
 173         put_net(ns->net_ns);
 174         kmem_cache_free(nsproxy_cachep, ns);
 175 }
 176
 177 /*
 178  * Called from unshare. Unshare all the namespaces part of nsproxy.
 179  * On success, returns the new nsproxy.
 180  */
 181 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 182                 struct nsproxy **new_nsp, struct fs_struct *new_fs)
 183 {
 184         int err = 0;
 185
 186         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 187                                CLONE_NEWNET)))
 188                 return 0;
 189
 190         if (!capable(CAP_SYS_ADMIN))
 191                 return -EPERM;
 192
 193         *new_nsp = create_new_namespaces(unshare_flags, current,
 194                                 new_fs ? new_fs : current->fs);
 195         if (IS_ERR(*new_nsp)) {
 196                 err = PTR_ERR(*new_nsp);
 197                 goto out;
 198         }
 199
 200         err = ns_cgroup_clone(current, task_pid(current));
 201         if (err)
 202                 put_nsproxy(*new_nsp);
 203
 204 out:
 205         return err;
 206 }
 207
 208 void 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
 230 void exit_task_namespaces(struct task_struct *p)
 231 {
 232         switch_task_namespaces(p, NULL);
 233 }
 234
 235 static int __init nsproxy_cache_init(void)
 236 {
 237         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
 238         return 0;
 239 }
 240
 241 module_init(nsproxy_cache_init);