Line data    Source code

       1             : /*
       2             :  *  Copyright (C) 2004 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             : 
      12             : #include <linux/export.h>
      13             : #include <linux/uts.h>
      14             : #include <linux/utsname.h>
      15             : #include <linux/err.h>
      16             : #include <linux/slab.h>
      17             : #include <linux/user_namespace.h>
      18             : #include <linux/proc_ns.h>
      19             : 
      20           0 : static struct uts_namespace *create_uts_ns(void)
      21             : {
      22             :         struct uts_namespace *uts_ns;
      23             : 
      24             :         uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
      25           0 :         if (uts_ns)
      26             :                 kref_init(&uts_ns->kref);
      27           0 :         return uts_ns;
      28             : }
      29             : 
      30             : /*
      31             :  * Clone a new ns copying an original utsname, setting refcount to 1
      32             :  * @old_ns: namespace to clone
      33             :  * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
      34             :  */
      35           0 : static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
      36             :                                           struct uts_namespace *old_ns)
      37             : {
      38             :         struct uts_namespace *ns;
      39             :         int err;
      40             : 
      41           0 :         ns = create_uts_ns();
      42           0 :         if (!ns)
      43             :                 return ERR_PTR(-ENOMEM);
      44             : 
      45             :         err = ns_alloc_inum(&ns->ns);
      46           0 :         if (err) {
      47           0 :                 kfree(ns);
      48             :                 return ERR_PTR(err);
      49             :         }
      50             : 
      51           0 :         ns->ns.ops = &utsns_operations;
      52             : 
      53           0 :         down_read(&uts_sem);
      54           0 :         memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
      55           0 :         ns->user_ns = get_user_ns(user_ns);
      56           0 :         up_read(&uts_sem);
      57             :         return ns;
      58             : }
      59             : 
      60             : /*
      61             :  * Copy task tsk's utsname namespace, or clone it if flags
      62             :  * specifies CLONE_NEWUTS.  In latter case, changes to the
      63             :  * utsname of this process won't be seen by parent, and vice
      64             :  * versa.
      65             :  */
      66           1 : struct uts_namespace *copy_utsname(unsigned long flags,
      67             :         struct user_namespace *user_ns, struct uts_namespace *old_ns)
      68             : {
      69             :         struct uts_namespace *new_ns;
      70             : 
      71             :         BUG_ON(!old_ns);
      72             :         get_uts_ns(old_ns);
      73             : 
      74           1 :         if (!(flags & CLONE_NEWUTS))
      75             :                 return old_ns;
      76             : 
      77           0 :         new_ns = clone_uts_ns(user_ns, old_ns);
      78             : 
      79             :         put_uts_ns(old_ns);
      80           0 :         return new_ns;
      81             : }
      82             : 
      83           0 : void free_uts_ns(struct kref *kref)
      84             : {
      85             :         struct uts_namespace *ns;
      86             : 
      87             :         ns = container_of(kref, struct uts_namespace, kref);
      88             :         put_user_ns(ns->user_ns);
      89           0 :         ns_free_inum(&ns->ns);
      90           0 :         kfree(ns);
      91           0 : }
      92             : 
      93             : static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
      94             : {
      95             :         return container_of(ns, struct uts_namespace, ns);
      96             : }
      97             : 
      98           0 : static struct ns_common *utsns_get(struct task_struct *task)
      99             : {
     100             :         struct uts_namespace *ns = NULL;
     101             :         struct nsproxy *nsproxy;
     102             : 
     103             :         task_lock(task);
     104           0 :         nsproxy = task->nsproxy;
     105           0 :         if (nsproxy) {
     106           0 :                 ns = nsproxy->uts_ns;
     107             :                 get_uts_ns(ns);
     108             :         }
     109             :         task_unlock(task);
     110             : 
     111           0 :         return ns ? &ns->ns : NULL;
     112             : }
     113             : 
     114           0 : static void utsns_put(struct ns_common *ns)
     115             : {
     116             :         put_uts_ns(to_uts_ns(ns));
     117           0 : }
     118             : 
     119           0 : static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
     120             : {
     121           0 :         struct uts_namespace *ns = to_uts_ns(new);
     122             : 
     123           0 :         if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
     124           0 :             !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
     125             :                 return -EPERM;
     126             : 
     127             :         get_uts_ns(ns);
     128           0 :         put_uts_ns(nsproxy->uts_ns);
     129           0 :         nsproxy->uts_ns = ns;
     130           0 :         return 0;
     131             : }
     132             : 
     133             : const struct proc_ns_operations utsns_operations = {
     134             :         .name           = "uts",
     135             :         .type           = CLONE_NEWUTS,
     136             :         .get            = utsns_get,
     137             :         .put            = utsns_put,
     138             :         .install        = utsns_install,
     139             : };