ipc/namespace.c

   1 /*
   2  * linux/ipc/namespace.c
   3  * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
   4  */
   5
   6 #include <linux/ipc.h>
   7 #include <linux/msg.h>
   8 #include <linux/ipc_namespace.h>
   9 #include <linux/rcupdate.h>
  10 #include <linux/nsproxy.h>
  11 #include <linux/slab.h>
  12
  13 #include "util.h"
  14
  15 static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
  16 {
  17         struct ipc_namespace *ns;
  18
  19         ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
  20         if (ns == NULL)
  21                 return ERR_PTR(-ENOMEM);
  22
  23         atomic_inc(&nr_ipc_ns);
  24
  25         sem_init_ns(ns);
  26         msg_init_ns(ns);
  27         shm_init_ns(ns);
  28
  29         register_ipcns_notifier(ns);
  30
  31         kref_init(&ns->kref);
  32         return ns;
  33 }
  34
  35 struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
  36 {
  37         struct ipc_namespace *new_ns;
  38
  39         BUG_ON(!ns);
  40         get_ipc_ns(ns);
  41
  42         if (!(flags & CLONE_NEWIPC))
  43                 return ns;
  44
  45         new_ns = clone_ipc_ns(ns);
  46
  47         put_ipc_ns(ns);
  48         return new_ns;
  49 }
  50
  51 /*
  52  * free_ipcs - free all ipcs of one type
  53  * @ns:   the namespace to remove the ipcs from
  54  * @ids:  the table of ipcs to free
  55  * @free: the function called to free each individual ipc
  56  *
  57  * Called for each kind of ipc when an ipc_namespace exits.
  58  */
  59 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
  60                void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
  61 {
  62         struct kern_ipc_perm *perm;
  63         int next_id;
  64         int total, in_use;
  65
  66         down_write(&ids->rw_mutex);
  67
  68         in_use = ids->in_use;
  69
  70         for (total = 0, next_id = 0; total < in_use; next_id++) {
  71                 perm = idr_find(&ids->ipcs_idr, next_id);
  72                 if (perm == NULL)
  73                         continue;
  74                 ipc_lock_by_ptr(perm);
  75                 free(ns, perm);
  76                 total++;
  77         }
  78         up_write(&ids->rw_mutex);
  79 }
  80
  81 void free_ipc_ns(struct kref *kref)
  82 {
  83         struct ipc_namespace *ns;
  84
  85         ns = container_of(kref, struct ipc_namespace, kref);
  86         /*
  87          * Unregistering the hotplug notifier at the beginning guarantees
  88          * that the ipc namespace won't be freed while we are inside the
  89          * callback routine. Since the blocking_notifier_chain_XXX routines
  90          * hold a rw lock on the notifier list, unregister_ipcns_notifier()
  91          * won't take the rw lock before blocking_notifier_call_chain() has
  92          * released the rd lock.
  93          */
  94         unregister_ipcns_notifier(ns);
  95         sem_exit_ns(ns);
  96         msg_exit_ns(ns);
  97         shm_exit_ns(ns);
  98         kfree(ns);
  99         atomic_dec(&nr_ipc_ns);
 100 }