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![Ingo Molnar](/assets/img/avatar_default.png)
Instead of including the full <linux/signal.h>, we are going to include the types-only <linux/signal_types.h> header in <linux/sched.h>, to further decouple the scheduler header from the signal headers. This means that various files which relied on the full <linux/signal.h> need to be updated to gain an explicit dependency on it. Update the code that relies on sched.h's inclusion of the <linux/signal.h> header. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
456 lines
11 KiB
C
456 lines
11 KiB
C
/*
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* Pid namespaces
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*
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* Authors:
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* (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
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* (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
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* Many thanks to Oleg Nesterov for comments and help
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*
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*/
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#include <linux/pid.h>
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#include <linux/pid_namespace.h>
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#include <linux/user_namespace.h>
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#include <linux/syscalls.h>
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#include <linux/cred.h>
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#include <linux/err.h>
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#include <linux/acct.h>
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#include <linux/slab.h>
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#include <linux/proc_ns.h>
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#include <linux/reboot.h>
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#include <linux/export.h>
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#include <linux/sched/task.h>
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#include <linux/sched/signal.h>
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struct pid_cache {
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int nr_ids;
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char name[16];
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struct kmem_cache *cachep;
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struct list_head list;
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};
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static LIST_HEAD(pid_caches_lh);
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static DEFINE_MUTEX(pid_caches_mutex);
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static struct kmem_cache *pid_ns_cachep;
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/*
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* creates the kmem cache to allocate pids from.
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* @nr_ids: the number of numerical ids this pid will have to carry
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*/
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static struct kmem_cache *create_pid_cachep(int nr_ids)
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{
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struct pid_cache *pcache;
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struct kmem_cache *cachep;
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mutex_lock(&pid_caches_mutex);
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list_for_each_entry(pcache, &pid_caches_lh, list)
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if (pcache->nr_ids == nr_ids)
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goto out;
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pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
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if (pcache == NULL)
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goto err_alloc;
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snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
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cachep = kmem_cache_create(pcache->name,
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sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
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0, SLAB_HWCACHE_ALIGN, NULL);
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if (cachep == NULL)
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goto err_cachep;
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pcache->nr_ids = nr_ids;
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pcache->cachep = cachep;
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list_add(&pcache->list, &pid_caches_lh);
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out:
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mutex_unlock(&pid_caches_mutex);
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return pcache->cachep;
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err_cachep:
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kfree(pcache);
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err_alloc:
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mutex_unlock(&pid_caches_mutex);
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return NULL;
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}
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static void proc_cleanup_work(struct work_struct *work)
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{
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struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work);
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pid_ns_release_proc(ns);
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}
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/* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
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#define MAX_PID_NS_LEVEL 32
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static struct ucounts *inc_pid_namespaces(struct user_namespace *ns)
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{
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return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES);
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}
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static void dec_pid_namespaces(struct ucounts *ucounts)
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{
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dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);
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}
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static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
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struct pid_namespace *parent_pid_ns)
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{
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struct pid_namespace *ns;
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unsigned int level = parent_pid_ns->level + 1;
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struct ucounts *ucounts;
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int i;
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int err;
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err = -ENOSPC;
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if (level > MAX_PID_NS_LEVEL)
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goto out;
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ucounts = inc_pid_namespaces(user_ns);
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if (!ucounts)
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goto out;
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err = -ENOMEM;
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ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
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if (ns == NULL)
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goto out_dec;
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ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
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if (!ns->pidmap[0].page)
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goto out_free;
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ns->pid_cachep = create_pid_cachep(level + 1);
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if (ns->pid_cachep == NULL)
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goto out_free_map;
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err = ns_alloc_inum(&ns->ns);
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if (err)
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goto out_free_map;
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ns->ns.ops = &pidns_operations;
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kref_init(&ns->kref);
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ns->level = level;
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ns->parent = get_pid_ns(parent_pid_ns);
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ns->user_ns = get_user_ns(user_ns);
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ns->ucounts = ucounts;
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ns->nr_hashed = PIDNS_HASH_ADDING;
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INIT_WORK(&ns->proc_work, proc_cleanup_work);
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set_bit(0, ns->pidmap[0].page);
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atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
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for (i = 1; i < PIDMAP_ENTRIES; i++)
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atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
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return ns;
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out_free_map:
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kfree(ns->pidmap[0].page);
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out_free:
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kmem_cache_free(pid_ns_cachep, ns);
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out_dec:
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dec_pid_namespaces(ucounts);
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out:
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return ERR_PTR(err);
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}
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static void delayed_free_pidns(struct rcu_head *p)
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{
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struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu);
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dec_pid_namespaces(ns->ucounts);
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put_user_ns(ns->user_ns);
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kmem_cache_free(pid_ns_cachep, ns);
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}
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static void destroy_pid_namespace(struct pid_namespace *ns)
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{
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int i;
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ns_free_inum(&ns->ns);
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for (i = 0; i < PIDMAP_ENTRIES; i++)
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kfree(ns->pidmap[i].page);
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call_rcu(&ns->rcu, delayed_free_pidns);
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}
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struct pid_namespace *copy_pid_ns(unsigned long flags,
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struct user_namespace *user_ns, struct pid_namespace *old_ns)
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{
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if (!(flags & CLONE_NEWPID))
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return get_pid_ns(old_ns);
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if (task_active_pid_ns(current) != old_ns)
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return ERR_PTR(-EINVAL);
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return create_pid_namespace(user_ns, old_ns);
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}
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static void free_pid_ns(struct kref *kref)
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{
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struct pid_namespace *ns;
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ns = container_of(kref, struct pid_namespace, kref);
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destroy_pid_namespace(ns);
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}
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void put_pid_ns(struct pid_namespace *ns)
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{
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struct pid_namespace *parent;
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while (ns != &init_pid_ns) {
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parent = ns->parent;
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if (!kref_put(&ns->kref, free_pid_ns))
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break;
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ns = parent;
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}
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}
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EXPORT_SYMBOL_GPL(put_pid_ns);
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void zap_pid_ns_processes(struct pid_namespace *pid_ns)
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{
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int nr;
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int rc;
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struct task_struct *task, *me = current;
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int init_pids = thread_group_leader(me) ? 1 : 2;
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/* Don't allow any more processes into the pid namespace */
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disable_pid_allocation(pid_ns);
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/*
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* Ignore SIGCHLD causing any terminated children to autoreap.
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* This speeds up the namespace shutdown, plus see the comment
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* below.
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*/
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spin_lock_irq(&me->sighand->siglock);
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me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
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spin_unlock_irq(&me->sighand->siglock);
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/*
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* The last thread in the cgroup-init thread group is terminating.
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* Find remaining pid_ts in the namespace, signal and wait for them
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* to exit.
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*
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* Note: This signals each threads in the namespace - even those that
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* belong to the same thread group, To avoid this, we would have
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* to walk the entire tasklist looking a processes in this
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* namespace, but that could be unnecessarily expensive if the
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* pid namespace has just a few processes. Or we need to
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* maintain a tasklist for each pid namespace.
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*
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*/
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read_lock(&tasklist_lock);
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nr = next_pidmap(pid_ns, 1);
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while (nr > 0) {
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rcu_read_lock();
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task = pid_task(find_vpid(nr), PIDTYPE_PID);
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if (task && !__fatal_signal_pending(task))
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send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
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rcu_read_unlock();
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nr = next_pidmap(pid_ns, nr);
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}
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read_unlock(&tasklist_lock);
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/*
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* Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
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* sys_wait4() will also block until our children traced from the
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* parent namespace are detached and become EXIT_DEAD.
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*/
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do {
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clear_thread_flag(TIF_SIGPENDING);
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rc = sys_wait4(-1, NULL, __WALL, NULL);
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} while (rc != -ECHILD);
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/*
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* sys_wait4() above can't reap the EXIT_DEAD children but we do not
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* really care, we could reparent them to the global init. We could
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* exit and reap ->child_reaper even if it is not the last thread in
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* this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
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* pid_ns can not go away until proc_kill_sb() drops the reference.
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*
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* But this ns can also have other tasks injected by setns()+fork().
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* Again, ignoring the user visible semantics we do not really need
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* to wait until they are all reaped, but they can be reparented to
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* us and thus we need to ensure that pid->child_reaper stays valid
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* until they all go away. See free_pid()->wake_up_process().
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*
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* We rely on ignored SIGCHLD, an injected zombie must be autoreaped
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* if reparented.
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*/
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for (;;) {
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set_current_state(TASK_UNINTERRUPTIBLE);
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if (pid_ns->nr_hashed == init_pids)
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break;
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schedule();
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}
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__set_current_state(TASK_RUNNING);
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if (pid_ns->reboot)
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current->signal->group_exit_code = pid_ns->reboot;
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acct_exit_ns(pid_ns);
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return;
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}
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#ifdef CONFIG_CHECKPOINT_RESTORE
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static int pid_ns_ctl_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct pid_namespace *pid_ns = task_active_pid_ns(current);
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struct ctl_table tmp = *table;
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if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
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return -EPERM;
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/*
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* Writing directly to ns' last_pid field is OK, since this field
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* is volatile in a living namespace anyway and a code writing to
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* it should synchronize its usage with external means.
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*/
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tmp.data = &pid_ns->last_pid;
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return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
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}
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extern int pid_max;
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static int zero = 0;
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static struct ctl_table pid_ns_ctl_table[] = {
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{
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.procname = "ns_last_pid",
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.maxlen = sizeof(int),
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.mode = 0666, /* permissions are checked in the handler */
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.proc_handler = pid_ns_ctl_handler,
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.extra1 = &zero,
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.extra2 = &pid_max,
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},
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{ }
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};
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static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
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#endif /* CONFIG_CHECKPOINT_RESTORE */
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int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
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{
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if (pid_ns == &init_pid_ns)
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return 0;
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switch (cmd) {
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case LINUX_REBOOT_CMD_RESTART2:
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case LINUX_REBOOT_CMD_RESTART:
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pid_ns->reboot = SIGHUP;
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break;
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case LINUX_REBOOT_CMD_POWER_OFF:
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case LINUX_REBOOT_CMD_HALT:
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pid_ns->reboot = SIGINT;
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break;
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default:
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return -EINVAL;
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}
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read_lock(&tasklist_lock);
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force_sig(SIGKILL, pid_ns->child_reaper);
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read_unlock(&tasklist_lock);
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do_exit(0);
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/* Not reached */
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return 0;
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}
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static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
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{
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return container_of(ns, struct pid_namespace, ns);
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}
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static struct ns_common *pidns_get(struct task_struct *task)
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{
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struct pid_namespace *ns;
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rcu_read_lock();
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ns = task_active_pid_ns(task);
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if (ns)
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get_pid_ns(ns);
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rcu_read_unlock();
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return ns ? &ns->ns : NULL;
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}
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static void pidns_put(struct ns_common *ns)
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{
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put_pid_ns(to_pid_ns(ns));
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}
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static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
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{
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struct pid_namespace *active = task_active_pid_ns(current);
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struct pid_namespace *ancestor, *new = to_pid_ns(ns);
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if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
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!ns_capable(current_user_ns(), CAP_SYS_ADMIN))
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return -EPERM;
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/*
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* Only allow entering the current active pid namespace
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* or a child of the current active pid namespace.
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*
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* This is required for fork to return a usable pid value and
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* this maintains the property that processes and their
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* children can not escape their current pid namespace.
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*/
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if (new->level < active->level)
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return -EINVAL;
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ancestor = new;
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while (ancestor->level > active->level)
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ancestor = ancestor->parent;
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if (ancestor != active)
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return -EINVAL;
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put_pid_ns(nsproxy->pid_ns_for_children);
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nsproxy->pid_ns_for_children = get_pid_ns(new);
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return 0;
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}
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static struct ns_common *pidns_get_parent(struct ns_common *ns)
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{
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struct pid_namespace *active = task_active_pid_ns(current);
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struct pid_namespace *pid_ns, *p;
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/* See if the parent is in the current namespace */
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pid_ns = p = to_pid_ns(ns)->parent;
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for (;;) {
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if (!p)
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return ERR_PTR(-EPERM);
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if (p == active)
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break;
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p = p->parent;
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}
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return &get_pid_ns(pid_ns)->ns;
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}
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static struct user_namespace *pidns_owner(struct ns_common *ns)
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{
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return to_pid_ns(ns)->user_ns;
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}
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const struct proc_ns_operations pidns_operations = {
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.name = "pid",
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.type = CLONE_NEWPID,
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.get = pidns_get,
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.put = pidns_put,
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.install = pidns_install,
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.owner = pidns_owner,
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.get_parent = pidns_get_parent,
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};
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static __init int pid_namespaces_init(void)
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{
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pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
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#ifdef CONFIG_CHECKPOINT_RESTORE
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register_sysctl_paths(kern_path, pid_ns_ctl_table);
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#endif
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return 0;
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}
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__initcall(pid_namespaces_init);
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