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 } 113