/* * Pid namespaces * * Authors: * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc. * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM * Many thanks to Oleg Nesterov for comments and help * */ #include <linux/pid.h> #include <linux/pid_namespace.h> #include <linux/syscalls.h> #include <linux/err.h> #include <linux/acct.h> #define BITS_PER_PAGE (PAGE_SIZE*8) struct pid_cache { int nr_ids; char name[16]; struct kmem_cache *cachep; struct list_head list; }; static LIST_HEAD(pid_caches_lh); static DEFINE_MUTEX(pid_caches_mutex); static struct kmem_cache *pid_ns_cachep; /* * creates the kmem cache to allocate pids from. * @nr_ids: the number of numerical ids this pid will have to carry */ static struct kmem_cache *create_pid_cachep(int nr_ids) { struct pid_cache *pcache; struct kmem_cache *cachep; mutex_lock(&pid_caches_mutex); list_for_each_entry(pcache, &pid_caches_lh, list) if (pcache->nr_ids == nr_ids) goto out; pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL); if (pcache == NULL) goto err_alloc; snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids); cachep = kmem_cache_create(pcache->name, sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid), 0, SLAB_HWCACHE_ALIGN, NULL); if (cachep == NULL) goto err_cachep; pcache->nr_ids = nr_ids; pcache->cachep = cachep; list_add(&pcache->list, &pid_caches_lh); out: mutex_unlock(&pid_caches_mutex); return pcache->cachep; err_cachep: kfree(pcache); err_alloc: mutex_unlock(&pid_caches_mutex); return NULL; } static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns) { struct pid_namespace *ns; unsigned int level = parent_pid_ns->level + 1; int i; ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); if (ns == NULL) goto out; ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); if (!ns->pidmap[0].page) goto out_free; ns->pid_cachep = create_pid_cachep(level + 1); if (ns->pid_cachep == NULL) goto out_free_map; kref_init(&ns->kref); ns->level = level; ns->parent = get_pid_ns(parent_pid_ns); set_bit(0, ns->pidmap[0].page); atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1); for (i = 1; i < PIDMAP_ENTRIES; i++) atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE); return ns; out_free_map: kfree(ns->pidmap[0].page); out_free: kmem_cache_free(pid_ns_cachep, ns); out: return ERR_PTR(-ENOMEM); } static void destroy_pid_namespace(struct pid_namespace *ns) { int i; for (i = 0; i < PIDMAP_ENTRIES; i++) kfree(ns->pidmap[i].page); kmem_cache_free(pid_ns_cachep, ns); } struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns) { if (!(flags & CLONE_NEWPID)) return get_pid_ns(old_ns); if (flags & (CLONE_THREAD|CLONE_PARENT)) return ERR_PTR(-EINVAL); return create_pid_namespace(old_ns); } void free_pid_ns(struct kref *kref) { struct pid_namespace *ns, *parent; ns = container_of(kref, struct pid_namespace, kref); parent = ns->parent; destroy_pid_namespace(ns); if (parent != NULL) put_pid_ns(parent); } void zap_pid_ns_processes(struct pid_namespace *pid_ns) { int nr; int rc; struct task_struct *task; /* * The last thread in the cgroup-init thread group is terminating. * Find remaining pid_ts in the namespace, signal and wait for them * to exit. * * Note: This signals each threads in the namespace - even those that * belong to the same thread group, To avoid this, we would have * to walk the entire tasklist looking a processes in this * namespace, but that could be unnecessarily expensive if the * pid namespace has just a few processes. Or we need to * maintain a tasklist for each pid namespace. * */ read_lock(&tasklist_lock); nr = next_pidmap(pid_ns, 1); while (nr > 0) { rcu_read_lock(); /* * Use force_sig() since it clears SIGNAL_UNKILLABLE ensuring * any nested-container's init processes don't ignore the * signal */ task = pid_task(find_vpid(nr), PIDTYPE_PID); if (task) force_sig(SIGKILL, task); rcu_read_unlock(); nr = next_pidmap(pid_ns, nr); } read_unlock(&tasklist_lock); do { clear_thread_flag(TIF_SIGPENDING); rc = sys_wait4(-1, NULL, __WALL, NULL); } while (rc != -ECHILD); acct_exit_ns(pid_ns); return; } static __init int pid_namespaces_init(void) { pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); return 0; } __initcall(pid_namespaces_init);