/* * 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> #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(int level) { struct pid_namespace *ns; int i; ns = kmem_cache_alloc(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->last_pid = 0; ns->child_reaper = NULL; ns->level = level; 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++) { ns->pidmap[i].page = NULL; 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) { struct pid_namespace *new_ns; BUG_ON(!old_ns); new_ns = get_pid_ns(old_ns); if (!(flags & CLONE_NEWPID)) goto out; new_ns = ERR_PTR(-EINVAL); if (flags & CLONE_THREAD) goto out_put; new_ns = create_pid_namespace(old_ns->level + 1); if (!IS_ERR(new_ns)) new_ns->parent = get_pid_ns(old_ns); out_put: put_pid_ns(old_ns); out: return new_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; /* * 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) { kill_proc_info(SIGKILL, SEND_SIG_PRIV, nr); 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); /* Child reaper for the pid namespace is going away */ pid_ns->child_reaper = NULL; return; } static __init int pid_namespaces_init(void) { pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); return 0; } __initcall(pid_namespaces_init);