| /* |
| * 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/user_namespace.h> |
| #include <linux/syscalls.h> |
| #include <linux/cred.h> |
| #include <linux/err.h> |
| #include <linux/acct.h> |
| #include <linux/slab.h> |
| #include <linux/proc_ns.h> |
| #include <linux/reboot.h> |
| #include <linux/export.h> |
| #include <linux/sched/task.h> |
| #include <linux/sched/signal.h> |
| |
| 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 void proc_cleanup_work(struct work_struct *work) |
| { |
| struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work); |
| pid_ns_release_proc(ns); |
| } |
| |
| /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */ |
| #define MAX_PID_NS_LEVEL 32 |
| |
| static struct ucounts *inc_pid_namespaces(struct user_namespace *ns) |
| { |
| return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES); |
| } |
| |
| static void dec_pid_namespaces(struct ucounts *ucounts) |
| { |
| dec_ucount(ucounts, UCOUNT_PID_NAMESPACES); |
| } |
| |
| static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns, |
| struct pid_namespace *parent_pid_ns) |
| { |
| struct pid_namespace *ns; |
| unsigned int level = parent_pid_ns->level + 1; |
| struct ucounts *ucounts; |
| int i; |
| int err; |
| |
| err = -ENOSPC; |
| if (level > MAX_PID_NS_LEVEL) |
| goto out; |
| ucounts = inc_pid_namespaces(user_ns); |
| if (!ucounts) |
| goto out; |
| |
| err = -ENOMEM; |
| ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); |
| if (ns == NULL) |
| goto out_dec; |
| |
| 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; |
| |
| err = ns_alloc_inum(&ns->ns); |
| if (err) |
| goto out_free_map; |
| ns->ns.ops = &pidns_operations; |
| |
| kref_init(&ns->kref); |
| ns->level = level; |
| ns->parent = get_pid_ns(parent_pid_ns); |
| ns->user_ns = get_user_ns(user_ns); |
| ns->ucounts = ucounts; |
| ns->nr_hashed = PIDNS_HASH_ADDING; |
| INIT_WORK(&ns->proc_work, proc_cleanup_work); |
| |
| 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_dec: |
| dec_pid_namespaces(ucounts); |
| out: |
| return ERR_PTR(err); |
| } |
| |
| static void delayed_free_pidns(struct rcu_head *p) |
| { |
| struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu); |
| |
| dec_pid_namespaces(ns->ucounts); |
| put_user_ns(ns->user_ns); |
| |
| kmem_cache_free(pid_ns_cachep, ns); |
| } |
| |
| static void destroy_pid_namespace(struct pid_namespace *ns) |
| { |
| int i; |
| |
| ns_free_inum(&ns->ns); |
| for (i = 0; i < PIDMAP_ENTRIES; i++) |
| kfree(ns->pidmap[i].page); |
| call_rcu(&ns->rcu, delayed_free_pidns); |
| } |
| |
| struct pid_namespace *copy_pid_ns(unsigned long flags, |
| struct user_namespace *user_ns, struct pid_namespace *old_ns) |
| { |
| if (!(flags & CLONE_NEWPID)) |
| return get_pid_ns(old_ns); |
| if (task_active_pid_ns(current) != old_ns) |
| return ERR_PTR(-EINVAL); |
| return create_pid_namespace(user_ns, old_ns); |
| } |
| |
| static void free_pid_ns(struct kref *kref) |
| { |
| struct pid_namespace *ns; |
| |
| ns = container_of(kref, struct pid_namespace, kref); |
| destroy_pid_namespace(ns); |
| } |
| |
| void put_pid_ns(struct pid_namespace *ns) |
| { |
| struct pid_namespace *parent; |
| |
| while (ns != &init_pid_ns) { |
| parent = ns->parent; |
| if (!kref_put(&ns->kref, free_pid_ns)) |
| break; |
| ns = parent; |
| } |
| } |
| EXPORT_SYMBOL_GPL(put_pid_ns); |
| |
| void zap_pid_ns_processes(struct pid_namespace *pid_ns) |
| { |
| int nr; |
| int rc; |
| struct task_struct *task, *me = current; |
| int init_pids = thread_group_leader(me) ? 1 : 2; |
| |
| /* Don't allow any more processes into the pid namespace */ |
| disable_pid_allocation(pid_ns); |
| |
| /* |
| * Ignore SIGCHLD causing any terminated children to autoreap. |
| * This speeds up the namespace shutdown, plus see the comment |
| * below. |
| */ |
| spin_lock_irq(&me->sighand->siglock); |
| me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN; |
| spin_unlock_irq(&me->sighand->siglock); |
| |
| /* |
| * 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(); |
| |
| task = pid_task(find_vpid(nr), PIDTYPE_PID); |
| if (task && !__fatal_signal_pending(task)) |
| send_sig_info(SIGKILL, SEND_SIG_FORCED, task); |
| |
| rcu_read_unlock(); |
| |
| nr = next_pidmap(pid_ns, nr); |
| } |
| read_unlock(&tasklist_lock); |
| |
| /* |
| * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD. |
| * sys_wait4() will also block until our children traced from the |
| * parent namespace are detached and become EXIT_DEAD. |
| */ |
| do { |
| clear_thread_flag(TIF_SIGPENDING); |
| rc = sys_wait4(-1, NULL, __WALL, NULL); |
| } while (rc != -ECHILD); |
| |
| /* |
| * sys_wait4() above can't reap the EXIT_DEAD children but we do not |
| * really care, we could reparent them to the global init. We could |
| * exit and reap ->child_reaper even if it is not the last thread in |
| * this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(), |
| * pid_ns can not go away until proc_kill_sb() drops the reference. |
| * |
| * But this ns can also have other tasks injected by setns()+fork(). |
| * Again, ignoring the user visible semantics we do not really need |
| * to wait until they are all reaped, but they can be reparented to |
| * us and thus we need to ensure that pid->child_reaper stays valid |
| * until they all go away. See free_pid()->wake_up_process(). |
| * |
| * We rely on ignored SIGCHLD, an injected zombie must be autoreaped |
| * if reparented. |
| */ |
| for (;;) { |
| set_current_state(TASK_UNINTERRUPTIBLE); |
| if (pid_ns->nr_hashed == init_pids) |
| break; |
| schedule(); |
| } |
| __set_current_state(TASK_RUNNING); |
| |
| if (pid_ns->reboot) |
| current->signal->group_exit_code = pid_ns->reboot; |
| |
| acct_exit_ns(pid_ns); |
| return; |
| } |
| |
| #ifdef CONFIG_CHECKPOINT_RESTORE |
| static int pid_ns_ctl_handler(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, loff_t *ppos) |
| { |
| struct pid_namespace *pid_ns = task_active_pid_ns(current); |
| struct ctl_table tmp = *table; |
| |
| if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN)) |
| return -EPERM; |
| |
| /* |
| * Writing directly to ns' last_pid field is OK, since this field |
| * is volatile in a living namespace anyway and a code writing to |
| * it should synchronize its usage with external means. |
| */ |
| |
| tmp.data = &pid_ns->last_pid; |
| return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); |
| } |
| |
| extern int pid_max; |
| static int zero = 0; |
| static struct ctl_table pid_ns_ctl_table[] = { |
| { |
| .procname = "ns_last_pid", |
| .maxlen = sizeof(int), |
| .mode = 0666, /* permissions are checked in the handler */ |
| .proc_handler = pid_ns_ctl_handler, |
| .extra1 = &zero, |
| .extra2 = &pid_max, |
| }, |
| { } |
| }; |
| static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } }; |
| #endif /* CONFIG_CHECKPOINT_RESTORE */ |
| |
| int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd) |
| { |
| if (pid_ns == &init_pid_ns) |
| return 0; |
| |
| switch (cmd) { |
| case LINUX_REBOOT_CMD_RESTART2: |
| case LINUX_REBOOT_CMD_RESTART: |
| pid_ns->reboot = SIGHUP; |
| break; |
| |
| case LINUX_REBOOT_CMD_POWER_OFF: |
| case LINUX_REBOOT_CMD_HALT: |
| pid_ns->reboot = SIGINT; |
| break; |
| default: |
| return -EINVAL; |
| } |
| |
| read_lock(&tasklist_lock); |
| force_sig(SIGKILL, pid_ns->child_reaper); |
| read_unlock(&tasklist_lock); |
| |
| do_exit(0); |
| |
| /* Not reached */ |
| return 0; |
| } |
| |
| static inline struct pid_namespace *to_pid_ns(struct ns_common *ns) |
| { |
| return container_of(ns, struct pid_namespace, ns); |
| } |
| |
| static struct ns_common *pidns_get(struct task_struct *task) |
| { |
| struct pid_namespace *ns; |
| |
| rcu_read_lock(); |
| ns = task_active_pid_ns(task); |
| if (ns) |
| get_pid_ns(ns); |
| rcu_read_unlock(); |
| |
| return ns ? &ns->ns : NULL; |
| } |
| |
| static void pidns_put(struct ns_common *ns) |
| { |
| put_pid_ns(to_pid_ns(ns)); |
| } |
| |
| static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns) |
| { |
| struct pid_namespace *active = task_active_pid_ns(current); |
| struct pid_namespace *ancestor, *new = to_pid_ns(ns); |
| |
| if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) || |
| !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) |
| return -EPERM; |
| |
| /* |
| * Only allow entering the current active pid namespace |
| * or a child of the current active pid namespace. |
| * |
| * This is required for fork to return a usable pid value and |
| * this maintains the property that processes and their |
| * children can not escape their current pid namespace. |
| */ |
| if (new->level < active->level) |
| return -EINVAL; |
| |
| ancestor = new; |
| while (ancestor->level > active->level) |
| ancestor = ancestor->parent; |
| if (ancestor != active) |
| return -EINVAL; |
| |
| put_pid_ns(nsproxy->pid_ns_for_children); |
| nsproxy->pid_ns_for_children = get_pid_ns(new); |
| return 0; |
| } |
| |
| static struct ns_common *pidns_get_parent(struct ns_common *ns) |
| { |
| struct pid_namespace *active = task_active_pid_ns(current); |
| struct pid_namespace *pid_ns, *p; |
| |
| /* See if the parent is in the current namespace */ |
| pid_ns = p = to_pid_ns(ns)->parent; |
| for (;;) { |
| if (!p) |
| return ERR_PTR(-EPERM); |
| if (p == active) |
| break; |
| p = p->parent; |
| } |
| |
| return &get_pid_ns(pid_ns)->ns; |
| } |
| |
| static struct user_namespace *pidns_owner(struct ns_common *ns) |
| { |
| return to_pid_ns(ns)->user_ns; |
| } |
| |
| const struct proc_ns_operations pidns_operations = { |
| .name = "pid", |
| .type = CLONE_NEWPID, |
| .get = pidns_get, |
| .put = pidns_put, |
| .install = pidns_install, |
| .owner = pidns_owner, |
| .get_parent = pidns_get_parent, |
| }; |
| |
| static __init int pid_namespaces_init(void) |
| { |
| pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); |
| |
| #ifdef CONFIG_CHECKPOINT_RESTORE |
| register_sysctl_paths(kern_path, pid_ns_ctl_table); |
| #endif |
| return 0; |
| } |
| |
| __initcall(pid_namespaces_init); |