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![Minchan Kim](/assets/img/avatar_default.png)
process_madvise syscall needs pidfd_get_pid function to translate pidfd to pid so this patch move the function to kernel/pid.c. Suggested-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jann Horn <jannh@google.com> Cc: Brian Geffon <bgeffon@google.com> Cc: Daniel Colascione <dancol@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: John Dias <joaodias@google.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oleksandr Natalenko <oleksandr@redhat.com> Cc: Sandeep Patil <sspatil@google.com> Cc: SeongJae Park <sj38.park@gmail.com> Cc: SeongJae Park <sjpark@amazon.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sonny Rao <sonnyrao@google.com> Cc: Tim Murray <timmurray@google.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: <linux-man@vger.kernel.org> Link: http://lkml.kernel.org/r/20200302193630.68771-5-minchan@kernel.org Link: http://lkml.kernel.org/r/20200622192900.22757-3-minchan@kernel.org Link: https://lkml.kernel.org/r/20200901000633.1920247-3-minchan@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
705 lines
17 KiB
C
705 lines
17 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Generic pidhash and scalable, time-bounded PID allocator
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*
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* (C) 2002-2003 Nadia Yvette Chambers, IBM
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* (C) 2004 Nadia Yvette Chambers, Oracle
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* (C) 2002-2004 Ingo Molnar, Red Hat
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*
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* pid-structures are backing objects for tasks sharing a given ID to chain
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* against. There is very little to them aside from hashing them and
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* parking tasks using given ID's on a list.
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*
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* The hash is always changed with the tasklist_lock write-acquired,
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* and the hash is only accessed with the tasklist_lock at least
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* read-acquired, so there's no additional SMP locking needed here.
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*
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* We have a list of bitmap pages, which bitmaps represent the PID space.
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* Allocating and freeing PIDs is completely lockless. The worst-case
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* allocation scenario when all but one out of 1 million PIDs possible are
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* allocated already: the scanning of 32 list entries and at most PAGE_SIZE
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* bytes. The typical fastpath is a single successful setbit. Freeing is O(1).
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*
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* Pid namespaces:
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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/mm.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/rculist.h>
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#include <linux/memblock.h>
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#include <linux/pid_namespace.h>
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#include <linux/init_task.h>
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#include <linux/syscalls.h>
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#include <linux/proc_ns.h>
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#include <linux/refcount.h>
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#include <linux/anon_inodes.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task.h>
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#include <linux/idr.h>
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#include <net/sock.h>
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#include <uapi/linux/pidfd.h>
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struct pid init_struct_pid = {
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.count = REFCOUNT_INIT(1),
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.tasks = {
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{ .first = NULL },
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{ .first = NULL },
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{ .first = NULL },
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},
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.level = 0,
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.numbers = { {
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.nr = 0,
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.ns = &init_pid_ns,
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}, }
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};
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int pid_max = PID_MAX_DEFAULT;
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#define RESERVED_PIDS 300
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int pid_max_min = RESERVED_PIDS + 1;
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int pid_max_max = PID_MAX_LIMIT;
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/*
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* PID-map pages start out as NULL, they get allocated upon
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* first use and are never deallocated. This way a low pid_max
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* value does not cause lots of bitmaps to be allocated, but
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* the scheme scales to up to 4 million PIDs, runtime.
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*/
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struct pid_namespace init_pid_ns = {
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.kref = KREF_INIT(2),
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.idr = IDR_INIT(init_pid_ns.idr),
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.pid_allocated = PIDNS_ADDING,
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.level = 0,
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.child_reaper = &init_task,
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.user_ns = &init_user_ns,
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.ns.inum = PROC_PID_INIT_INO,
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#ifdef CONFIG_PID_NS
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.ns.ops = &pidns_operations,
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#endif
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};
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EXPORT_SYMBOL_GPL(init_pid_ns);
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/*
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* Note: disable interrupts while the pidmap_lock is held as an
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* interrupt might come in and do read_lock(&tasklist_lock).
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*
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* If we don't disable interrupts there is a nasty deadlock between
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* detach_pid()->free_pid() and another cpu that does
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* spin_lock(&pidmap_lock) followed by an interrupt routine that does
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* read_lock(&tasklist_lock);
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*
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* After we clean up the tasklist_lock and know there are no
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* irq handlers that take it we can leave the interrupts enabled.
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* For now it is easier to be safe than to prove it can't happen.
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*/
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static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
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void put_pid(struct pid *pid)
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{
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struct pid_namespace *ns;
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if (!pid)
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return;
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ns = pid->numbers[pid->level].ns;
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if (refcount_dec_and_test(&pid->count)) {
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kmem_cache_free(ns->pid_cachep, pid);
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put_pid_ns(ns);
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}
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}
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EXPORT_SYMBOL_GPL(put_pid);
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static void delayed_put_pid(struct rcu_head *rhp)
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{
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struct pid *pid = container_of(rhp, struct pid, rcu);
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put_pid(pid);
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}
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void free_pid(struct pid *pid)
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{
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/* We can be called with write_lock_irq(&tasklist_lock) held */
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int i;
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unsigned long flags;
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spin_lock_irqsave(&pidmap_lock, flags);
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for (i = 0; i <= pid->level; i++) {
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struct upid *upid = pid->numbers + i;
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struct pid_namespace *ns = upid->ns;
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switch (--ns->pid_allocated) {
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case 2:
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case 1:
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/* When all that is left in the pid namespace
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* is the reaper wake up the reaper. The reaper
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* may be sleeping in zap_pid_ns_processes().
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*/
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wake_up_process(ns->child_reaper);
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break;
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case PIDNS_ADDING:
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/* Handle a fork failure of the first process */
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WARN_ON(ns->child_reaper);
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ns->pid_allocated = 0;
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break;
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}
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idr_remove(&ns->idr, upid->nr);
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}
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spin_unlock_irqrestore(&pidmap_lock, flags);
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call_rcu(&pid->rcu, delayed_put_pid);
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}
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struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
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size_t set_tid_size)
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{
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struct pid *pid;
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enum pid_type type;
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int i, nr;
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struct pid_namespace *tmp;
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struct upid *upid;
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int retval = -ENOMEM;
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/*
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* set_tid_size contains the size of the set_tid array. Starting at
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* the most nested currently active PID namespace it tells alloc_pid()
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* which PID to set for a process in that most nested PID namespace
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* up to set_tid_size PID namespaces. It does not have to set the PID
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* for a process in all nested PID namespaces but set_tid_size must
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* never be greater than the current ns->level + 1.
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*/
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if (set_tid_size > ns->level + 1)
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return ERR_PTR(-EINVAL);
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pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
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if (!pid)
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return ERR_PTR(retval);
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tmp = ns;
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pid->level = ns->level;
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for (i = ns->level; i >= 0; i--) {
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int tid = 0;
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if (set_tid_size) {
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tid = set_tid[ns->level - i];
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retval = -EINVAL;
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if (tid < 1 || tid >= pid_max)
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goto out_free;
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/*
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* Also fail if a PID != 1 is requested and
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* no PID 1 exists.
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*/
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if (tid != 1 && !tmp->child_reaper)
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goto out_free;
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retval = -EPERM;
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if (!checkpoint_restore_ns_capable(tmp->user_ns))
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goto out_free;
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set_tid_size--;
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}
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idr_preload(GFP_KERNEL);
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spin_lock_irq(&pidmap_lock);
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if (tid) {
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nr = idr_alloc(&tmp->idr, NULL, tid,
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tid + 1, GFP_ATOMIC);
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/*
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* If ENOSPC is returned it means that the PID is
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* alreay in use. Return EEXIST in that case.
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*/
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if (nr == -ENOSPC)
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nr = -EEXIST;
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} else {
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int pid_min = 1;
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/*
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* init really needs pid 1, but after reaching the
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* maximum wrap back to RESERVED_PIDS
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*/
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if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS)
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pid_min = RESERVED_PIDS;
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/*
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* Store a null pointer so find_pid_ns does not find
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* a partially initialized PID (see below).
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*/
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nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
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pid_max, GFP_ATOMIC);
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}
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spin_unlock_irq(&pidmap_lock);
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idr_preload_end();
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if (nr < 0) {
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retval = (nr == -ENOSPC) ? -EAGAIN : nr;
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goto out_free;
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}
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pid->numbers[i].nr = nr;
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pid->numbers[i].ns = tmp;
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tmp = tmp->parent;
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}
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/*
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* ENOMEM is not the most obvious choice especially for the case
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* where the child subreaper has already exited and the pid
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* namespace denies the creation of any new processes. But ENOMEM
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* is what we have exposed to userspace for a long time and it is
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* documented behavior for pid namespaces. So we can't easily
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* change it even if there were an error code better suited.
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*/
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retval = -ENOMEM;
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get_pid_ns(ns);
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refcount_set(&pid->count, 1);
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spin_lock_init(&pid->lock);
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for (type = 0; type < PIDTYPE_MAX; ++type)
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INIT_HLIST_HEAD(&pid->tasks[type]);
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init_waitqueue_head(&pid->wait_pidfd);
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INIT_HLIST_HEAD(&pid->inodes);
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upid = pid->numbers + ns->level;
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spin_lock_irq(&pidmap_lock);
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if (!(ns->pid_allocated & PIDNS_ADDING))
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goto out_unlock;
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for ( ; upid >= pid->numbers; --upid) {
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/* Make the PID visible to find_pid_ns. */
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idr_replace(&upid->ns->idr, pid, upid->nr);
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upid->ns->pid_allocated++;
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}
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spin_unlock_irq(&pidmap_lock);
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return pid;
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out_unlock:
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spin_unlock_irq(&pidmap_lock);
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put_pid_ns(ns);
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out_free:
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spin_lock_irq(&pidmap_lock);
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while (++i <= ns->level) {
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upid = pid->numbers + i;
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idr_remove(&upid->ns->idr, upid->nr);
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}
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/* On failure to allocate the first pid, reset the state */
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if (ns->pid_allocated == PIDNS_ADDING)
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idr_set_cursor(&ns->idr, 0);
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spin_unlock_irq(&pidmap_lock);
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kmem_cache_free(ns->pid_cachep, pid);
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return ERR_PTR(retval);
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}
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void disable_pid_allocation(struct pid_namespace *ns)
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{
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spin_lock_irq(&pidmap_lock);
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ns->pid_allocated &= ~PIDNS_ADDING;
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spin_unlock_irq(&pidmap_lock);
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}
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struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
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{
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return idr_find(&ns->idr, nr);
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}
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EXPORT_SYMBOL_GPL(find_pid_ns);
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struct pid *find_vpid(int nr)
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{
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return find_pid_ns(nr, task_active_pid_ns(current));
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}
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EXPORT_SYMBOL_GPL(find_vpid);
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static struct pid **task_pid_ptr(struct task_struct *task, enum pid_type type)
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{
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return (type == PIDTYPE_PID) ?
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&task->thread_pid :
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&task->signal->pids[type];
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}
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/*
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* attach_pid() must be called with the tasklist_lock write-held.
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*/
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void attach_pid(struct task_struct *task, enum pid_type type)
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{
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struct pid *pid = *task_pid_ptr(task, type);
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hlist_add_head_rcu(&task->pid_links[type], &pid->tasks[type]);
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}
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static void __change_pid(struct task_struct *task, enum pid_type type,
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struct pid *new)
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{
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struct pid **pid_ptr = task_pid_ptr(task, type);
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struct pid *pid;
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int tmp;
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pid = *pid_ptr;
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hlist_del_rcu(&task->pid_links[type]);
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*pid_ptr = new;
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for (tmp = PIDTYPE_MAX; --tmp >= 0; )
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if (pid_has_task(pid, tmp))
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return;
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free_pid(pid);
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}
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void detach_pid(struct task_struct *task, enum pid_type type)
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{
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__change_pid(task, type, NULL);
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}
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void change_pid(struct task_struct *task, enum pid_type type,
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struct pid *pid)
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{
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__change_pid(task, type, pid);
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attach_pid(task, type);
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}
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void exchange_tids(struct task_struct *left, struct task_struct *right)
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{
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struct pid *pid1 = left->thread_pid;
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struct pid *pid2 = right->thread_pid;
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struct hlist_head *head1 = &pid1->tasks[PIDTYPE_PID];
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struct hlist_head *head2 = &pid2->tasks[PIDTYPE_PID];
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/* Swap the single entry tid lists */
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hlists_swap_heads_rcu(head1, head2);
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/* Swap the per task_struct pid */
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rcu_assign_pointer(left->thread_pid, pid2);
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rcu_assign_pointer(right->thread_pid, pid1);
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/* Swap the cached value */
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WRITE_ONCE(left->pid, pid_nr(pid2));
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WRITE_ONCE(right->pid, pid_nr(pid1));
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}
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/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
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void transfer_pid(struct task_struct *old, struct task_struct *new,
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enum pid_type type)
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{
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if (type == PIDTYPE_PID)
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new->thread_pid = old->thread_pid;
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hlist_replace_rcu(&old->pid_links[type], &new->pid_links[type]);
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}
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struct task_struct *pid_task(struct pid *pid, enum pid_type type)
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{
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struct task_struct *result = NULL;
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if (pid) {
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struct hlist_node *first;
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first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
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lockdep_tasklist_lock_is_held());
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if (first)
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result = hlist_entry(first, struct task_struct, pid_links[(type)]);
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}
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return result;
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}
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EXPORT_SYMBOL(pid_task);
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/*
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* Must be called under rcu_read_lock().
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*/
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struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
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{
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RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
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"find_task_by_pid_ns() needs rcu_read_lock() protection");
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return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
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}
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struct task_struct *find_task_by_vpid(pid_t vnr)
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{
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return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
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}
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struct task_struct *find_get_task_by_vpid(pid_t nr)
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{
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struct task_struct *task;
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rcu_read_lock();
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task = find_task_by_vpid(nr);
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if (task)
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get_task_struct(task);
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rcu_read_unlock();
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return task;
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}
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struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
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{
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struct pid *pid;
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rcu_read_lock();
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pid = get_pid(rcu_dereference(*task_pid_ptr(task, type)));
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rcu_read_unlock();
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return pid;
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}
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EXPORT_SYMBOL_GPL(get_task_pid);
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struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
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{
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struct task_struct *result;
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rcu_read_lock();
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result = pid_task(pid, type);
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if (result)
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get_task_struct(result);
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rcu_read_unlock();
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return result;
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}
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EXPORT_SYMBOL_GPL(get_pid_task);
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struct pid *find_get_pid(pid_t nr)
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{
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struct pid *pid;
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rcu_read_lock();
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pid = get_pid(find_vpid(nr));
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rcu_read_unlock();
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return pid;
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}
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EXPORT_SYMBOL_GPL(find_get_pid);
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pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
|
|
{
|
|
struct upid *upid;
|
|
pid_t nr = 0;
|
|
|
|
if (pid && ns->level <= pid->level) {
|
|
upid = &pid->numbers[ns->level];
|
|
if (upid->ns == ns)
|
|
nr = upid->nr;
|
|
}
|
|
return nr;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pid_nr_ns);
|
|
|
|
pid_t pid_vnr(struct pid *pid)
|
|
{
|
|
return pid_nr_ns(pid, task_active_pid_ns(current));
|
|
}
|
|
EXPORT_SYMBOL_GPL(pid_vnr);
|
|
|
|
pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
|
|
struct pid_namespace *ns)
|
|
{
|
|
pid_t nr = 0;
|
|
|
|
rcu_read_lock();
|
|
if (!ns)
|
|
ns = task_active_pid_ns(current);
|
|
nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns);
|
|
rcu_read_unlock();
|
|
|
|
return nr;
|
|
}
|
|
EXPORT_SYMBOL(__task_pid_nr_ns);
|
|
|
|
struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
|
|
{
|
|
return ns_of_pid(task_pid(tsk));
|
|
}
|
|
EXPORT_SYMBOL_GPL(task_active_pid_ns);
|
|
|
|
/*
|
|
* Used by proc to find the first pid that is greater than or equal to nr.
|
|
*
|
|
* If there is a pid at nr this function is exactly the same as find_pid_ns.
|
|
*/
|
|
struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
|
|
{
|
|
return idr_get_next(&ns->idr, &nr);
|
|
}
|
|
|
|
struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags)
|
|
{
|
|
struct fd f;
|
|
struct pid *pid;
|
|
|
|
f = fdget(fd);
|
|
if (!f.file)
|
|
return ERR_PTR(-EBADF);
|
|
|
|
pid = pidfd_pid(f.file);
|
|
if (!IS_ERR(pid)) {
|
|
get_pid(pid);
|
|
*flags = f.file->f_flags;
|
|
}
|
|
|
|
fdput(f);
|
|
return pid;
|
|
}
|
|
|
|
/**
|
|
* pidfd_create() - Create a new pid file descriptor.
|
|
*
|
|
* @pid: struct pid that the pidfd will reference
|
|
* @flags: flags to pass
|
|
*
|
|
* This creates a new pid file descriptor with the O_CLOEXEC flag set.
|
|
*
|
|
* Note, that this function can only be called after the fd table has
|
|
* been unshared to avoid leaking the pidfd to the new process.
|
|
*
|
|
* Return: On success, a cloexec pidfd is returned.
|
|
* On error, a negative errno number will be returned.
|
|
*/
|
|
static int pidfd_create(struct pid *pid, unsigned int flags)
|
|
{
|
|
int fd;
|
|
|
|
fd = anon_inode_getfd("[pidfd]", &pidfd_fops, get_pid(pid),
|
|
flags | O_RDWR | O_CLOEXEC);
|
|
if (fd < 0)
|
|
put_pid(pid);
|
|
|
|
return fd;
|
|
}
|
|
|
|
/**
|
|
* pidfd_open() - Open new pid file descriptor.
|
|
*
|
|
* @pid: pid for which to retrieve a pidfd
|
|
* @flags: flags to pass
|
|
*
|
|
* This creates a new pid file descriptor with the O_CLOEXEC flag set for
|
|
* the process identified by @pid. Currently, the process identified by
|
|
* @pid must be a thread-group leader. This restriction currently exists
|
|
* for all aspects of pidfds including pidfd creation (CLONE_PIDFD cannot
|
|
* be used with CLONE_THREAD) and pidfd polling (only supports thread group
|
|
* leaders).
|
|
*
|
|
* Return: On success, a cloexec pidfd is returned.
|
|
* On error, a negative errno number will be returned.
|
|
*/
|
|
SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags)
|
|
{
|
|
int fd;
|
|
struct pid *p;
|
|
|
|
if (flags & ~PIDFD_NONBLOCK)
|
|
return -EINVAL;
|
|
|
|
if (pid <= 0)
|
|
return -EINVAL;
|
|
|
|
p = find_get_pid(pid);
|
|
if (!p)
|
|
return -ESRCH;
|
|
|
|
if (pid_has_task(p, PIDTYPE_TGID))
|
|
fd = pidfd_create(p, flags);
|
|
else
|
|
fd = -EINVAL;
|
|
|
|
put_pid(p);
|
|
return fd;
|
|
}
|
|
|
|
void __init pid_idr_init(void)
|
|
{
|
|
/* Verify no one has done anything silly: */
|
|
BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_ADDING);
|
|
|
|
/* bump default and minimum pid_max based on number of cpus */
|
|
pid_max = min(pid_max_max, max_t(int, pid_max,
|
|
PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
|
|
pid_max_min = max_t(int, pid_max_min,
|
|
PIDS_PER_CPU_MIN * num_possible_cpus());
|
|
pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);
|
|
|
|
idr_init(&init_pid_ns.idr);
|
|
|
|
init_pid_ns.pid_cachep = KMEM_CACHE(pid,
|
|
SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
|
|
}
|
|
|
|
static struct file *__pidfd_fget(struct task_struct *task, int fd)
|
|
{
|
|
struct file *file;
|
|
int ret;
|
|
|
|
ret = mutex_lock_killable(&task->signal->exec_update_mutex);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
|
|
if (ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS))
|
|
file = fget_task(task, fd);
|
|
else
|
|
file = ERR_PTR(-EPERM);
|
|
|
|
mutex_unlock(&task->signal->exec_update_mutex);
|
|
|
|
return file ?: ERR_PTR(-EBADF);
|
|
}
|
|
|
|
static int pidfd_getfd(struct pid *pid, int fd)
|
|
{
|
|
struct task_struct *task;
|
|
struct file *file;
|
|
int ret;
|
|
|
|
task = get_pid_task(pid, PIDTYPE_PID);
|
|
if (!task)
|
|
return -ESRCH;
|
|
|
|
file = __pidfd_fget(task, fd);
|
|
put_task_struct(task);
|
|
if (IS_ERR(file))
|
|
return PTR_ERR(file);
|
|
|
|
ret = receive_fd(file, O_CLOEXEC);
|
|
fput(file);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sys_pidfd_getfd() - Get a file descriptor from another process
|
|
*
|
|
* @pidfd: the pidfd file descriptor of the process
|
|
* @fd: the file descriptor number to get
|
|
* @flags: flags on how to get the fd (reserved)
|
|
*
|
|
* This syscall gets a copy of a file descriptor from another process
|
|
* based on the pidfd, and file descriptor number. It requires that
|
|
* the calling process has the ability to ptrace the process represented
|
|
* by the pidfd. The process which is having its file descriptor copied
|
|
* is otherwise unaffected.
|
|
*
|
|
* Return: On success, a cloexec file descriptor is returned.
|
|
* On error, a negative errno number will be returned.
|
|
*/
|
|
SYSCALL_DEFINE3(pidfd_getfd, int, pidfd, int, fd,
|
|
unsigned int, flags)
|
|
{
|
|
struct pid *pid;
|
|
struct fd f;
|
|
int ret;
|
|
|
|
/* flags is currently unused - make sure it's unset */
|
|
if (flags)
|
|
return -EINVAL;
|
|
|
|
f = fdget(pidfd);
|
|
if (!f.file)
|
|
return -EBADF;
|
|
|
|
pid = pidfd_pid(f.file);
|
|
if (IS_ERR(pid))
|
|
ret = PTR_ERR(pid);
|
|
else
|
|
ret = pidfd_getfd(pid, fd);
|
|
|
|
fdput(f);
|
|
return ret;
|
|
}
|