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