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/slab.h>
  17 #include <linux/export.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_ns.h>
  26 #include <linux/file.h>
  27 #include <linux/syscalls.h>
  28 #include <linux/cgroup.h>
  29
  30 static struct kmem_cache *nsproxy_cachep;
  31
  32 struct nsproxy init_nsproxy = {
  33         .count                  = ATOMIC_INIT(1),
  34         .uts_ns                 = &init_uts_ns,
  35 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
  36         .ipc_ns                 = &init_ipc_ns,
  37 #endif
  38         .mnt_ns                 = NULL,
  39         .pid_ns_for_children    = &init_pid_ns,
  40 #ifdef CONFIG_NET
  41         .net_ns                 = &init_net,
  42 #endif
  43 #ifdef CONFIG_CGROUPS
  44         .cgroup_ns              = &init_cgroup_ns,
  45 #endif
  46 };
  47
  48 static inline struct nsproxy *create_nsproxy(void)
  49 {
  50         struct nsproxy *nsproxy;
  51
  52         nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
  53         if (nsproxy)
  54                 atomic_set(&nsproxy->count, 1);
  55         return nsproxy;
  56 }
  57
  58 /*
  59  * Create new nsproxy and all of its the associated namespaces.
  60  * Return the newly created nsproxy.  Do not attach this to the task,
  61  * leave it to the caller to do proper locking and attach it to task.
  62  */
  63 static struct nsproxy *create_new_namespaces(unsigned long flags,
  64         struct task_struct *tsk, struct user_namespace *user_ns,
  65         struct fs_struct *new_fs)
  66 {
  67         struct nsproxy *new_nsp;
  68         int err;
  69
  70         new_nsp = create_nsproxy();
  71         if (!new_nsp)
  72                 return ERR_PTR(-ENOMEM);
  73
  74         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
  75         if (IS_ERR(new_nsp->mnt_ns)) {
  76                 err = PTR_ERR(new_nsp->mnt_ns);
  77                 goto out_ns;
  78         }
  79
  80         new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
  81         if (IS_ERR(new_nsp->uts_ns)) {
  82                 err = PTR_ERR(new_nsp->uts_ns);
  83                 goto out_uts;
  84         }
  85
  86         new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
  87         if (IS_ERR(new_nsp->ipc_ns)) {
  88                 err = PTR_ERR(new_nsp->ipc_ns);
  89                 goto out_ipc;
  90         }
  91
  92         new_nsp->pid_ns_for_children =
  93                 copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);
  94         if (IS_ERR(new_nsp->pid_ns_for_children)) {
  95                 err = PTR_ERR(new_nsp->pid_ns_for_children);
  96                 goto out_pid;
  97         }
  98
  99         new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns,
 100                                             tsk->nsproxy->cgroup_ns);
 101         if (IS_ERR(new_nsp->cgroup_ns)) {
 102                 err = PTR_ERR(new_nsp->cgroup_ns);
 103                 goto out_cgroup;
 104         }
 105
 106         new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
 107         if (IS_ERR(new_nsp->net_ns)) {
 108                 err = PTR_ERR(new_nsp->net_ns);
 109                 goto out_net;
 110         }
 111
 112         return new_nsp;
 113
 114 out_net:
 115         put_cgroup_ns(new_nsp->cgroup_ns);
 116 out_cgroup:
 117         if (new_nsp->pid_ns_for_children)
 118                 put_pid_ns(new_nsp->pid_ns_for_children);
 119 out_pid:
 120         if (new_nsp->ipc_ns)
 121                 put_ipc_ns(new_nsp->ipc_ns);
 122 out_ipc:
 123         if (new_nsp->uts_ns)
 124                 put_uts_ns(new_nsp->uts_ns);
 125 out_uts:
 126         if (new_nsp->mnt_ns)
 127                 put_mnt_ns(new_nsp->mnt_ns);
 128 out_ns:
 129         kmem_cache_free(nsproxy_cachep, new_nsp);
 130         return ERR_PTR(err);
 131 }
 132
 133 /*
 134  * called from clone.  This now handles copy for nsproxy and all
 135  * namespaces therein.
 136  */
 137 int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 138 {
 139         struct nsproxy *old_ns = tsk->nsproxy;
 140         struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
 141         struct nsproxy *new_ns;
 142
 143         if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 144                               CLONE_NEWPID | CLONE_NEWNET |
 145                               CLONE_NEWCGROUP)))) {
 146                 get_nsproxy(old_ns);
 147                 return 0;
 148         }
 149
 150         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 151                 return -EPERM;
 152
 153         /*
 154          * CLONE_NEWIPC must detach from the undolist: after switching
 155          * to a new ipc namespace, the semaphore arrays from the old
 156          * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
 157          * means share undolist with parent, so we must forbid using
 158          * it along with CLONE_NEWIPC.
 159          */
 160         if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
 161                 (CLONE_NEWIPC | CLONE_SYSVSEM))
 162                 return -EINVAL;
 163
 164         new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
 165         if (IS_ERR(new_ns))
 166                 return  PTR_ERR(new_ns);
 167
 168         tsk->nsproxy = new_ns;
 169         return 0;
 170 }
 171
 172 void free_nsproxy(struct nsproxy *ns)
 173 {
 174         if (ns->mnt_ns)
 175                 put_mnt_ns(ns->mnt_ns);
 176         if (ns->uts_ns)
 177                 put_uts_ns(ns->uts_ns);
 178         if (ns->ipc_ns)
 179                 put_ipc_ns(ns->ipc_ns);
 180         if (ns->pid_ns_for_children)
 181                 put_pid_ns(ns->pid_ns_for_children);
 182         put_cgroup_ns(ns->cgroup_ns);
 183         put_net(ns->net_ns);
 184         kmem_cache_free(nsproxy_cachep, ns);
 185 }
 186
 187 /*
 188  * Called from unshare. Unshare all the namespaces part of nsproxy.
 189  * On success, returns the new nsproxy.
 190  */
 191 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 192         struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
 193 {
 194         struct user_namespace *user_ns;
 195         int err = 0;
 196
 197         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 198                                CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP)))
 199                 return 0;
 200
 201         user_ns = new_cred ? new_cred->user_ns : current_user_ns();
 202         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 203                 return -EPERM;
 204
 205         *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
 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 out:
 213         return err;
 214 }
 215
 216 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
 217 {
 218         struct nsproxy *ns;
 219
 220         might_sleep();
 221
 222         task_lock(p);
 223         ns = p->nsproxy;
 224         p->nsproxy = new;
 225         task_unlock(p);
 226
 227         if (ns && atomic_dec_and_test(&ns->count))
 228                 free_nsproxy(ns);
 229 }
 230
 231 void exit_task_namespaces(struct task_struct *p)
 232 {
 233         switch_task_namespaces(p, NULL);
 234 }
 235
 236 SYSCALL_DEFINE2(setns, int, fd, int, nstype)
 237 {
 238         struct task_struct *tsk = current;
 239         struct nsproxy *new_nsproxy;
 240         struct file *file;
 241         struct ns_common *ns;
 242         int err;
 243
 244         file = proc_ns_fget(fd);
 245         if (IS_ERR(file))
 246                 return PTR_ERR(file);
 247
 248         err = -EINVAL;
 249         ns = get_proc_ns(file_inode(file));
 250         if (nstype && (ns->ops->type != nstype))
 251                 goto out;
 252
 253         new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
 254         if (IS_ERR(new_nsproxy)) {
 255                 err = PTR_ERR(new_nsproxy);
 256                 goto out;
 257         }
 258
 259         err = ns->ops->install(new_nsproxy, ns);
 260         if (err) {
 261                 free_nsproxy(new_nsproxy);
 262                 goto out;
 263         }
 264         switch_task_namespaces(tsk, new_nsproxy);
 265 out:
 266         fput(file);
 267         return err;
 268 }
 269
 270 int __init nsproxy_cache_init(void)
 271 {
 272         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
 273         return 0;
 274 }