#include <linux/rcupdate.h>
#include <linux/nsproxy.h>
#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/user_namespace.h>
+#include <linux/proc_fs.h>
#include "util.h"
-static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
+static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,
+ struct ipc_namespace *old_ns)
{
struct ipc_namespace *ns;
+ int err;
ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
if (ns == NULL)
return ERR_PTR(-ENOMEM);
+ 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);
- kref_init(&ns->kref);
+ /*
+ * 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);
+
+ ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
+
return ns;
}
-struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
+struct ipc_namespace *copy_ipcs(unsigned long flags,
+ struct task_struct *tsk)
{
- struct ipc_namespace *new_ns;
-
- BUG_ON(!ns);
- get_ipc_ns(ns);
+ struct ipc_namespace *ns = tsk->nsproxy->ipc_ns;
if (!(flags & CLONE_NEWIPC))
- return ns;
+ return get_ipc_ns(ns);
+ return create_ipc_ns(tsk, 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;
+
+ 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);
+ 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_user_ns(ns->user_ns);
kfree(ns);
}
+
+/*
+ * 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);
+ }
+}
+
+static void *ipcns_get(struct task_struct *task)
+{
+ struct ipc_namespace *ns = NULL;
+ struct nsproxy *nsproxy;
+
+ rcu_read_lock();
+ nsproxy = task_nsproxy(task);
+ if (nsproxy)
+ ns = get_ipc_ns(nsproxy->ipc_ns);
+ rcu_read_unlock();
+
+ return ns;
+}
+
+static void ipcns_put(void *ns)
+{
+ return put_ipc_ns(ns);
+}
+
+static int ipcns_install(struct nsproxy *nsproxy, void *ns)
+{
+ /* Ditch state from the old ipc namespace */
+ exit_sem(current);
+ put_ipc_ns(nsproxy->ipc_ns);
+ nsproxy->ipc_ns = get_ipc_ns(ns);
+ return 0;
+}
+
+const struct proc_ns_operations ipcns_operations = {
+ .name = "ipc",
+ .type = CLONE_NEWIPC,
+ .get = ipcns_get,
+ .put = ipcns_put,
+ .install = ipcns_install,
+};
Code Review / linux-2.6.git / blobdiff