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         mq_init_ns(ns);
  29
  30         /*
  31          * msgmni has already been computed for the new ipc ns.
  32          * Thus, do the ipcns creation notification before registering that
  33          * new ipcns in the chain.
  34          */
  35         ipcns_notify(IPCNS_CREATED);
  36         register_ipcns_notifier(ns);
  37
  38         kref_init(&ns->kref);
  39         return ns;
  40 }
  41
  42 struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
  43 {
  44         struct ipc_namespace *new_ns;
  45
  46         BUG_ON(!ns);
  47         get_ipc_ns(ns);
  48
  49         if (!(flags & CLONE_NEWIPC))
  50                 return ns;
  51
  52         new_ns = clone_ipc_ns(ns);
  53
  54         put_ipc_ns(ns);
  55         return new_ns;
  56 }
  57
  58 /*
  59  * free_ipcs - free all ipcs of one type
  60  * @ns:   the namespace to remove the ipcs from
  61  * @ids:  the table of ipcs to free
  62  * @free: the function called to free each individual ipc
  63  *
  64  * Called for each kind of ipc when an ipc_namespace exits.
  65  */
  66 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
  67                void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
  68 {
  69         struct kern_ipc_perm *perm;
  70         int next_id;
  71         int total, in_use;
  72
  73         down_write(&ids->rw_mutex);
  74
  75         in_use = ids->in_use;
  76
  77         for (total = 0, next_id = 0; total < in_use; next_id++) {
  78                 perm = idr_find(&ids->ipcs_idr, next_id);
  79                 if (perm == NULL)
  80                         continue;
  81                 ipc_lock_by_ptr(perm);
  82                 free(ns, perm);
  83                 total++;
  84         }
  85         up_write(&ids->rw_mutex);
  86 }
  87
  88 void free_ipc_ns(struct kref *kref)
  89 {
  90         struct ipc_namespace *ns;
  91
  92         ns = container_of(kref, struct ipc_namespace, kref);
  93         /*
  94          * Unregistering the hotplug notifier at the beginning guarantees
  95          * that the ipc namespace won't be freed while we are inside the
  96          * callback routine. Since the blocking_notifier_chain_XXX routines
  97          * hold a rw lock on the notifier list, unregister_ipcns_notifier()
  98          * won't take the rw lock before blocking_notifier_call_chain() has
  99          * released the rd lock.
 100          */
 101         unregister_ipcns_notifier(ns);
 102         sem_exit_ns(ns);
 103         msg_exit_ns(ns);
 104         shm_exit_ns(ns);
 105         mq_exit_ns(ns);
 106         kfree(ns);
 107         atomic_dec(&nr_ipc_ns);
 108
 109         /*
 110          * Do the ipcns removal notification after decrementing nr_ipc_ns in
 111          * order to have a correct value when recomputing msgmni.
 112          */
 113         ipcns_notify(IPCNS_REMOVED);
 114 }