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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * 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>
 #include <linux/idr.h>
 
 static DEFINE_MUTEX(pid_caches_mutex);
 static struct kmem_cache *pid_ns_cachep;
 /* Write once array, filled from the beginning. */
 static struct kmem_cache *pid_cache[MAX_PID_NS_LEVEL];
 
 /*
  * creates the kmem cache to allocate pids from.
  * @level: pid namespace level
  */
 
 static struct kmem_cache *create_pid_cachep(unsigned int level)
 {
     /* Level 0 is init_pid_ns.pid_cachep */
     struct kmem_cache **pkc = &pid_cache[level - 1];
     struct kmem_cache *kc;
     char name[4 + 10 + 1];
     unsigned int len;
 
     kc = READ_ONCE(*pkc);
     if (kc)
         return kc;
 
     snprintf(name, sizeof(name), "pid_%u", level + 1);
     len = sizeof(struct pid) + level * sizeof(struct upid);
     mutex_lock(&pid_caches_mutex);
     /* Name collision forces to do allocation under mutex. */
     if (!*pkc)
         *pkc = kmem_cache_create(name, len, 0,
                      SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT, NULL);
     mutex_unlock(&pid_caches_mutex);
     /* current can fail, but someone else can succeed. */
     return READ_ONCE(*pkc);
 }
 
 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 err;
 
     err = -EINVAL;
     if (!in_userns(parent_pid_ns->user_ns, user_ns))
         goto out;
 
     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;
 
     idr_init(&ns->idr);
 
     ns->pid_cachep = create_pid_cachep(level);
     if (ns->pid_cachep == NULL)
         goto out_free_idr;
 
     err = ns_alloc_inum(&ns->ns);
     if (err)
         goto out_free_idr;
     ns->ns.ops = &pidns_operations;
 
     refcount_set(&ns->ns.count, 1);
     ns->level = level;
     ns->parent = get_pid_ns(parent_pid_ns);
     ns->user_ns = get_user_ns(user_ns);
     ns->ucounts = ucounts;
     ns->pid_allocated = PIDNS_ADDING;
 
     return ns;
 
 out_free_idr:
     idr_destroy(&ns->idr);
     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)
 {
     ns_free_inum(&ns->ns);
 
     idr_destroy(&ns->idr);
     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);
 }
 
 void put_pid_ns(struct pid_namespace *ns)
 {
     struct pid_namespace *parent;
 
     while (ns != &init_pid_ns) {
         parent = ns->parent;
         if (!refcount_dec_and_test(&ns->ns.count))
             break;
         destroy_pid_namespace(ns);
         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;
     struct pid *pid;
 
     /* 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.
      *
      */
     rcu_read_lock();
     read_lock(&tasklist_lock);
     nr = 2;
     idr_for_each_entry_continue(&pid_ns->idr, pid, nr) {
         task = pid_task(pid, PIDTYPE_PID);
         if (task && !__fatal_signal_pending(task))
             group_send_sig_info(SIGKILL, SEND_SIG_PRIV, task, PIDTYPE_MAX);
     }
     read_unlock(&tasklist_lock);
     rcu_read_unlock();
 
     /*
      * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
      * kernel_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 = kernel_wait4(-1, NULL, __WALL, NULL);
     } while (rc != -ECHILD);
 
     /*
      * kernel_wait4() misses EXIT_DEAD children, and EXIT_ZOMBIE
      * process whose parents processes are outside of the pid
      * namespace.  Such processes are created with setns()+fork().
      *
      * If those EXIT_ZOMBIE processes are not reaped by their
      * parents before their parents exit, they will be reparented
      * to pid_ns->child_reaper.  Thus pidns->child_reaper needs to
      * stay valid until they all go away.
      *
      * The code relies on the pid_ns->child_reaper ignoring
      * SIGCHILD to cause those EXIT_ZOMBIE processes to be
      * autoreaped if reparented.
      *
      * Semantically it is also desirable to wait for EXIT_ZOMBIE
      * processes before allowing the child_reaper to be reaped, as
      * that gives the invariant that when the init process of a
      * pid namespace is reaped all of the processes in the pid
      * namespace are gone.
      *
      * Once all of the other tasks are gone from the pid_namespace
      * free_pid() will awaken this task.
      */
     for (;;) {
         set_current_state(TASK_INTERRUPTIBLE);
         if (pid_ns->pid_allocated == 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 *buffer, size_t *lenp, loff_t *ppos)
 {
     struct pid_namespace *pid_ns = task_active_pid_ns(current);
     struct ctl_table tmp = *table;
     int ret, next;
 
     if (write && !checkpoint_restore_ns_capable(pid_ns->user_ns))
         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.
      */
 
     next = idr_get_cursor(&pid_ns->idr) - 1;
 
     tmp.data = &next;
     ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
     if (!ret && write)
         idr_set_cursor(&pid_ns->idr, next + 1);
 
     return ret;
 }
 
 extern int pid_max;
 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 = SYSCTL_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);
     send_sig(SIGKILL, pid_ns->child_reaper, 1);
     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 struct ns_common *pidns_for_children_get(struct task_struct *task)
 {
     struct pid_namespace *ns = NULL;
 
     task_lock(task);
     if (task->nsproxy) {
         ns = task->nsproxy->pid_ns_for_children;
         get_pid_ns(ns);
     }
     task_unlock(task);
 
     if (ns) {
         read_lock(&tasklist_lock);
         if (!ns->child_reaper) {
             put_pid_ns(ns);
             ns = NULL;
         }
         read_unlock(&tasklist_lock);
     }
 
     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 nsset *nsset, struct ns_common *ns)
 {
     struct nsproxy *nsproxy = nsset->nsproxy;
     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(nsset->cred->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,
 };
 
 const struct proc_ns_operations pidns_for_children_operations = {
     .name       = "pid_for_children",
     .real_ns_name   = "pid",
     .type       = CLONE_NEWPID,
     .get        = pidns_for_children_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 | SLAB_ACCOUNT);
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
     register_sysctl_paths(kern_path, pid_ns_ctl_table);
 #endif
     return 0;
 }
 
 __initcall(pid_namespaces_init);

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