X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=ipc%2Fnamespace.c;h=a1094ff0befa2775c5e9023c44c1520ff813ad04;hb=dbb6be6d5e974c42bbecd183effaa0df69e1dd8b;hp=cef1139e6c96f49162cff04e32026257597d6f2d;hpb=ae5e1b22f17983da929a0d0178896269e19da186;p=safe%2Fjmp%2Flinux-2.6

diff --git a/ipc/namespace.c b/ipc/namespace.c
index cef1139..a1094ff 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -9,65 +9,126 @@
 #include <linux/rcupdate.h>
 #include <linux/nsproxy.h>
 #include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
 
 #include "util.h"
 
-static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
+static struct ipc_namespace *create_ipc_ns(void)
 {
-	int err;
 	struct ipc_namespace *ns;
+	int err;
 
-	err = -ENOMEM;
 	ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
 	if (ns == NULL)
-		goto err_mem;
-
-	err = sem_init_ns(ns);
-	if (err)
-		goto err_sem;
-	err = msg_init_ns(ns);
-	if (err)
-		goto err_msg;
-	err = shm_init_ns(ns);
-	if (err)
-		goto err_shm;
-
-	kref_init(&ns->kref);
-	return ns;
+		return ERR_PTR(-ENOMEM);
 
-err_shm:
-	msg_exit_ns(ns);
-err_msg:
-	sem_exit_ns(ns);
-err_sem:
-	kfree(ns);
-err_mem:
-	return ERR_PTR(err);
+	atomic_set(&ns->count, 1);
+	err = mq_init_ns(ns);
+	if (err) {
+		kfree(ns);
+		return ERR_PTR(err);
+	}
+	atomic_inc(&nr_ipc_ns);
+
+	sem_init_ns(ns);
+	msg_init_ns(ns);
+	shm_init_ns(ns);
+
+	/*
+	 * msgmni has already been computed for the new ipc ns.
+	 * Thus, do the ipcns creation notification before registering that
+	 * new ipcns in the chain.
+	 */
+	ipcns_notify(IPCNS_CREATED);
+	register_ipcns_notifier(ns);
+
+	return ns;
 }
 
 struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
 {
-	struct ipc_namespace *new_ns;
+	if (!(flags & CLONE_NEWIPC))
+		return get_ipc_ns(ns);
+	return create_ipc_ns();
+}
 
-	BUG_ON(!ns);
-	get_ipc_ns(ns);
+/*
+ * free_ipcs - free all ipcs of one type
+ * @ns:   the namespace to remove the ipcs from
+ * @ids:  the table of ipcs to free
+ * @free: the function called to free each individual ipc
+ *
+ * Called for each kind of ipc when an ipc_namespace exits.
+ */
+void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
+	       void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
+{
+	struct kern_ipc_perm *perm;
+	int next_id;
+	int total, in_use;
 
-	if (!(flags & CLONE_NEWIPC))
-		return ns;
+	down_write(&ids->rw_mutex);
 
-	new_ns = clone_ipc_ns(ns);
+	in_use = ids->in_use;
 
-	put_ipc_ns(ns);
-	return new_ns;
+	for (total = 0, next_id = 0; total < in_use; next_id++) {
+		perm = idr_find(&ids->ipcs_idr, next_id);
+		if (perm == NULL)
+			continue;
+		ipc_lock_by_ptr(perm);
+		free(ns, perm);
+		total++;
+	}
+	up_write(&ids->rw_mutex);
 }
 
-void free_ipc_ns(struct kref *kref)
+static void free_ipc_ns(struct ipc_namespace *ns)
 {
-	struct ipc_namespace *ns;
-
-	ns = container_of(kref, struct ipc_namespace, kref);
+	/*
+	 * Unregistering the hotplug notifier at the beginning guarantees
+	 * that the ipc namespace won't be freed while we are inside the
+	 * callback routine. Since the blocking_notifier_chain_XXX routines
+	 * hold a rw lock on the notifier list, unregister_ipcns_notifier()
+	 * won't take the rw lock before blocking_notifier_call_chain() has
+	 * released the rd lock.
+	 */
+	unregister_ipcns_notifier(ns);
 	sem_exit_ns(ns);
 	msg_exit_ns(ns);
 	shm_exit_ns(ns);
 	kfree(ns);
+	atomic_dec(&nr_ipc_ns);
+
+	/*
+	 * Do the ipcns removal notification after decrementing nr_ipc_ns in
+	 * order to have a correct value when recomputing msgmni.
+	 */
+	ipcns_notify(IPCNS_REMOVED);
+}
+
+/*
+ * put_ipc_ns - drop a reference to an ipc namespace.
+ * @ns: the namespace to put
+ *
+ * If this is the last task in the namespace exiting, and
+ * it is dropping the refcount to 0, then it can race with
+ * a task in another ipc namespace but in a mounts namespace
+ * which has this ipcns's mqueuefs mounted, doing some action
+ * with one of the mqueuefs files.  That can raise the refcount.
+ * So dropping the refcount, and raising the refcount when
+ * accessing it through the VFS, are protected with mq_lock.
+ *
+ * (Clearly, a task raising the refcount on its own ipc_ns
+ * needn't take mq_lock since it can't race with the last task
+ * in the ipcns exiting).
+ */
+void put_ipc_ns(struct ipc_namespace *ns)
+{
+	if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
+		mq_clear_sbinfo(ns);
+		spin_unlock(&mq_lock);
+		mq_put_mnt(ns);
+		free_ipc_ns(ns);
+	}
 }