| /* |
| * linux/ipc/namespace.c |
| * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc. |
| */ |
| |
| #include <linux/ipc.h> |
| #include <linux/msg.h> |
| #include <linux/ipc_namespace.h> |
| #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_ns.h> |
| |
| #include "util.h" |
| |
| static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns, |
| 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); |
| |
| err = proc_alloc_inum(&ns->proc_inum); |
| if (err) { |
| kfree(ns); |
| return ERR_PTR(err); |
| } |
| |
| atomic_set(&ns->count, 1); |
| err = mq_init_ns(ns); |
| if (err) { |
| proc_free_inum(ns->proc_inum); |
| 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); |
| |
| ns->user_ns = get_user_ns(user_ns); |
| |
| return ns; |
| } |
| |
| struct ipc_namespace *copy_ipcs(unsigned long flags, |
| struct user_namespace *user_ns, struct ipc_namespace *ns) |
| { |
| if (!(flags & CLONE_NEWIPC)) |
| return get_ipc_ns(ns); |
| return create_ipc_ns(user_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; |
| |
| down_write(&ids->rwsem); |
| |
| in_use = ids->in_use; |
| |
| for (total = 0, next_id = 0; total < in_use; next_id++) { |
| perm = idr_find(&ids->ipcs_idr, next_id); |
| if (perm == NULL) |
| continue; |
| rcu_read_lock(); |
| ipc_lock_object(perm); |
| free(ns, perm); |
| total++; |
| } |
| up_write(&ids->rwsem); |
| } |
| |
| static void free_ipc_ns(struct ipc_namespace *ns) |
| { |
| /* |
| * 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); |
| proc_free_inum(ns->proc_inum); |
| 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 *new) |
| { |
| struct ipc_namespace *ns = new; |
| if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) || |
| !nsown_capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| |
| /* 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; |
| } |
| |
| static unsigned int ipcns_inum(void *vp) |
| { |
| struct ipc_namespace *ns = vp; |
| |
| return ns->proc_inum; |
| } |
| |
| const struct proc_ns_operations ipcns_operations = { |
| .name = "ipc", |
| .type = CLONE_NEWIPC, |
| .get = ipcns_get, |
| .put = ipcns_put, |
| .install = ipcns_install, |
| .inum = ipcns_inum, |
| }; |