2 * This program is free software; you can redistribute it and/or
3 * modify it under the terms of the GNU General Public License as
4 * published by the Free Software Foundation, version 2 of the
8 #include <linux/export.h>
9 #include <linux/nsproxy.h>
10 #include <linux/slab.h>
11 #include <linux/user_namespace.h>
12 #include <linux/proc_fs.h>
13 #include <linux/highuid.h>
14 #include <linux/cred.h>
15 #include <linux/securebits.h>
16 #include <linux/keyctl.h>
17 #include <linux/key-type.h>
18 #include <keys/user-type.h>
19 #include <linux/seq_file.h>
21 #include <linux/uaccess.h>
22 #include <linux/ctype.h>
23 #include <linux/projid.h>
24 #include <linux/fs_struct.h>
26 static struct kmem_cache
*user_ns_cachep __read_mostly
;
28 static bool new_idmap_permitted(struct user_namespace
*ns
, int cap_setid
,
29 struct uid_gid_map
*map
);
31 static void set_cred_user_ns(struct cred
*cred
, struct user_namespace
*user_ns
)
33 /* Start with the same capabilities as init but useless for doing
34 * anything as the capabilities are bound to the new user namespace.
36 cred
->securebits
= SECUREBITS_DEFAULT
;
37 cred
->cap_inheritable
= CAP_EMPTY_SET
;
38 cred
->cap_permitted
= CAP_FULL_SET
;
39 cred
->cap_effective
= CAP_FULL_SET
;
40 cred
->cap_bset
= CAP_FULL_SET
;
42 key_put(cred
->request_key_auth
);
43 cred
->request_key_auth
= NULL
;
45 /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
46 cred
->user_ns
= user_ns
;
50 * Create a new user namespace, deriving the creator from the user in the
51 * passed credentials, and replacing that user with the new root user for the
54 * This is called by copy_creds(), which will finish setting the target task's
57 int create_user_ns(struct cred
*new)
59 struct user_namespace
*ns
, *parent_ns
= new->user_ns
;
60 kuid_t owner
= new->euid
;
61 kgid_t group
= new->egid
;
64 /* The creator needs a mapping in the parent user namespace
65 * or else we won't be able to reasonably tell userspace who
66 * created a user_namespace.
68 if (!kuid_has_mapping(parent_ns
, owner
) ||
69 !kgid_has_mapping(parent_ns
, group
))
72 ns
= kmem_cache_zalloc(user_ns_cachep
, GFP_KERNEL
);
76 ret
= proc_alloc_inum(&ns
->proc_inum
);
78 kmem_cache_free(user_ns_cachep
, ns
);
82 atomic_set(&ns
->count
, 1);
83 /* Leave the new->user_ns reference with the new user namespace. */
84 ns
->parent
= parent_ns
;
88 set_cred_user_ns(new, ns
);
93 int unshare_userns(unsigned long unshare_flags
, struct cred
**new_cred
)
97 if (!(unshare_flags
& CLONE_NEWUSER
))
100 cred
= prepare_creds();
105 return create_user_ns(cred
);
108 void free_user_ns(struct user_namespace
*ns
)
110 struct user_namespace
*parent
;
114 proc_free_inum(ns
->proc_inum
);
115 kmem_cache_free(user_ns_cachep
, ns
);
117 } while (atomic_dec_and_test(&parent
->count
));
119 EXPORT_SYMBOL(free_user_ns
);
121 static u32
map_id_range_down(struct uid_gid_map
*map
, u32 id
, u32 count
)
123 unsigned idx
, extents
;
124 u32 first
, last
, id2
;
126 id2
= id
+ count
- 1;
128 /* Find the matching extent */
129 extents
= map
->nr_extents
;
130 smp_read_barrier_depends();
131 for (idx
= 0; idx
< extents
; idx
++) {
132 first
= map
->extent
[idx
].first
;
133 last
= first
+ map
->extent
[idx
].count
- 1;
134 if (id
>= first
&& id
<= last
&&
135 (id2
>= first
&& id2
<= last
))
138 /* Map the id or note failure */
140 id
= (id
- first
) + map
->extent
[idx
].lower_first
;
147 static u32
map_id_down(struct uid_gid_map
*map
, u32 id
)
149 unsigned idx
, extents
;
152 /* Find the matching extent */
153 extents
= map
->nr_extents
;
154 smp_read_barrier_depends();
155 for (idx
= 0; idx
< extents
; idx
++) {
156 first
= map
->extent
[idx
].first
;
157 last
= first
+ map
->extent
[idx
].count
- 1;
158 if (id
>= first
&& id
<= last
)
161 /* Map the id or note failure */
163 id
= (id
- first
) + map
->extent
[idx
].lower_first
;
170 static u32
map_id_up(struct uid_gid_map
*map
, u32 id
)
172 unsigned idx
, extents
;
175 /* Find the matching extent */
176 extents
= map
->nr_extents
;
177 smp_read_barrier_depends();
178 for (idx
= 0; idx
< extents
; idx
++) {
179 first
= map
->extent
[idx
].lower_first
;
180 last
= first
+ map
->extent
[idx
].count
- 1;
181 if (id
>= first
&& id
<= last
)
184 /* Map the id or note failure */
186 id
= (id
- first
) + map
->extent
[idx
].first
;
194 * make_kuid - Map a user-namespace uid pair into a kuid.
195 * @ns: User namespace that the uid is in
196 * @uid: User identifier
198 * Maps a user-namespace uid pair into a kernel internal kuid,
199 * and returns that kuid.
201 * When there is no mapping defined for the user-namespace uid
202 * pair INVALID_UID is returned. Callers are expected to test
203 * for and handle handle INVALID_UID being returned. INVALID_UID
204 * may be tested for using uid_valid().
206 kuid_t
make_kuid(struct user_namespace
*ns
, uid_t uid
)
208 /* Map the uid to a global kernel uid */
209 return KUIDT_INIT(map_id_down(&ns
->uid_map
, uid
));
211 EXPORT_SYMBOL(make_kuid
);
214 * from_kuid - Create a uid from a kuid user-namespace pair.
215 * @targ: The user namespace we want a uid in.
216 * @kuid: The kernel internal uid to start with.
218 * Map @kuid into the user-namespace specified by @targ and
219 * return the resulting uid.
221 * There is always a mapping into the initial user_namespace.
223 * If @kuid has no mapping in @targ (uid_t)-1 is returned.
225 uid_t
from_kuid(struct user_namespace
*targ
, kuid_t kuid
)
227 /* Map the uid from a global kernel uid */
228 return map_id_up(&targ
->uid_map
, __kuid_val(kuid
));
230 EXPORT_SYMBOL(from_kuid
);
233 * from_kuid_munged - Create a uid from a kuid user-namespace pair.
234 * @targ: The user namespace we want a uid in.
235 * @kuid: The kernel internal uid to start with.
237 * Map @kuid into the user-namespace specified by @targ and
238 * return the resulting uid.
240 * There is always a mapping into the initial user_namespace.
242 * Unlike from_kuid from_kuid_munged never fails and always
243 * returns a valid uid. This makes from_kuid_munged appropriate
244 * for use in syscalls like stat and getuid where failing the
245 * system call and failing to provide a valid uid are not an
248 * If @kuid has no mapping in @targ overflowuid is returned.
250 uid_t
from_kuid_munged(struct user_namespace
*targ
, kuid_t kuid
)
253 uid
= from_kuid(targ
, kuid
);
255 if (uid
== (uid_t
) -1)
259 EXPORT_SYMBOL(from_kuid_munged
);
262 * make_kgid - Map a user-namespace gid pair into a kgid.
263 * @ns: User namespace that the gid is in
264 * @uid: group identifier
266 * Maps a user-namespace gid pair into a kernel internal kgid,
267 * and returns that kgid.
269 * When there is no mapping defined for the user-namespace gid
270 * pair INVALID_GID is returned. Callers are expected to test
271 * for and handle INVALID_GID being returned. INVALID_GID may be
272 * tested for using gid_valid().
274 kgid_t
make_kgid(struct user_namespace
*ns
, gid_t gid
)
276 /* Map the gid to a global kernel gid */
277 return KGIDT_INIT(map_id_down(&ns
->gid_map
, gid
));
279 EXPORT_SYMBOL(make_kgid
);
282 * from_kgid - Create a gid from a kgid user-namespace pair.
283 * @targ: The user namespace we want a gid in.
284 * @kgid: The kernel internal gid to start with.
286 * Map @kgid into the user-namespace specified by @targ and
287 * return the resulting gid.
289 * There is always a mapping into the initial user_namespace.
291 * If @kgid has no mapping in @targ (gid_t)-1 is returned.
293 gid_t
from_kgid(struct user_namespace
*targ
, kgid_t kgid
)
295 /* Map the gid from a global kernel gid */
296 return map_id_up(&targ
->gid_map
, __kgid_val(kgid
));
298 EXPORT_SYMBOL(from_kgid
);
301 * from_kgid_munged - Create a gid from a kgid user-namespace pair.
302 * @targ: The user namespace we want a gid in.
303 * @kgid: The kernel internal gid to start with.
305 * Map @kgid into the user-namespace specified by @targ and
306 * return the resulting gid.
308 * There is always a mapping into the initial user_namespace.
310 * Unlike from_kgid from_kgid_munged never fails and always
311 * returns a valid gid. This makes from_kgid_munged appropriate
312 * for use in syscalls like stat and getgid where failing the
313 * system call and failing to provide a valid gid are not options.
315 * If @kgid has no mapping in @targ overflowgid is returned.
317 gid_t
from_kgid_munged(struct user_namespace
*targ
, kgid_t kgid
)
320 gid
= from_kgid(targ
, kgid
);
322 if (gid
== (gid_t
) -1)
326 EXPORT_SYMBOL(from_kgid_munged
);
329 * make_kprojid - Map a user-namespace projid pair into a kprojid.
330 * @ns: User namespace that the projid is in
331 * @projid: Project identifier
333 * Maps a user-namespace uid pair into a kernel internal kuid,
334 * and returns that kuid.
336 * When there is no mapping defined for the user-namespace projid
337 * pair INVALID_PROJID is returned. Callers are expected to test
338 * for and handle handle INVALID_PROJID being returned. INVALID_PROJID
339 * may be tested for using projid_valid().
341 kprojid_t
make_kprojid(struct user_namespace
*ns
, projid_t projid
)
343 /* Map the uid to a global kernel uid */
344 return KPROJIDT_INIT(map_id_down(&ns
->projid_map
, projid
));
346 EXPORT_SYMBOL(make_kprojid
);
349 * from_kprojid - Create a projid from a kprojid user-namespace pair.
350 * @targ: The user namespace we want a projid in.
351 * @kprojid: The kernel internal project identifier to start with.
353 * Map @kprojid into the user-namespace specified by @targ and
354 * return the resulting projid.
356 * There is always a mapping into the initial user_namespace.
358 * If @kprojid has no mapping in @targ (projid_t)-1 is returned.
360 projid_t
from_kprojid(struct user_namespace
*targ
, kprojid_t kprojid
)
362 /* Map the uid from a global kernel uid */
363 return map_id_up(&targ
->projid_map
, __kprojid_val(kprojid
));
365 EXPORT_SYMBOL(from_kprojid
);
368 * from_kprojid_munged - Create a projiid from a kprojid user-namespace pair.
369 * @targ: The user namespace we want a projid in.
370 * @kprojid: The kernel internal projid to start with.
372 * Map @kprojid into the user-namespace specified by @targ and
373 * return the resulting projid.
375 * There is always a mapping into the initial user_namespace.
377 * Unlike from_kprojid from_kprojid_munged never fails and always
378 * returns a valid projid. This makes from_kprojid_munged
379 * appropriate for use in syscalls like stat and where
380 * failing the system call and failing to provide a valid projid are
383 * If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned.
385 projid_t
from_kprojid_munged(struct user_namespace
*targ
, kprojid_t kprojid
)
388 projid
= from_kprojid(targ
, kprojid
);
390 if (projid
== (projid_t
) -1)
391 projid
= OVERFLOW_PROJID
;
394 EXPORT_SYMBOL(from_kprojid_munged
);
397 static int uid_m_show(struct seq_file
*seq
, void *v
)
399 struct user_namespace
*ns
= seq
->private;
400 struct uid_gid_extent
*extent
= v
;
401 struct user_namespace
*lower_ns
;
404 lower_ns
= seq_user_ns(seq
);
405 if ((lower_ns
== ns
) && lower_ns
->parent
)
406 lower_ns
= lower_ns
->parent
;
408 lower
= from_kuid(lower_ns
, KUIDT_INIT(extent
->lower_first
));
410 seq_printf(seq
, "%10u %10u %10u\n",
418 static int gid_m_show(struct seq_file
*seq
, void *v
)
420 struct user_namespace
*ns
= seq
->private;
421 struct uid_gid_extent
*extent
= v
;
422 struct user_namespace
*lower_ns
;
425 lower_ns
= seq_user_ns(seq
);
426 if ((lower_ns
== ns
) && lower_ns
->parent
)
427 lower_ns
= lower_ns
->parent
;
429 lower
= from_kgid(lower_ns
, KGIDT_INIT(extent
->lower_first
));
431 seq_printf(seq
, "%10u %10u %10u\n",
439 static int projid_m_show(struct seq_file
*seq
, void *v
)
441 struct user_namespace
*ns
= seq
->private;
442 struct uid_gid_extent
*extent
= v
;
443 struct user_namespace
*lower_ns
;
446 lower_ns
= seq_user_ns(seq
);
447 if ((lower_ns
== ns
) && lower_ns
->parent
)
448 lower_ns
= lower_ns
->parent
;
450 lower
= from_kprojid(lower_ns
, KPROJIDT_INIT(extent
->lower_first
));
452 seq_printf(seq
, "%10u %10u %10u\n",
460 static void *m_start(struct seq_file
*seq
, loff_t
*ppos
, struct uid_gid_map
*map
)
462 struct uid_gid_extent
*extent
= NULL
;
465 if (pos
< map
->nr_extents
)
466 extent
= &map
->extent
[pos
];
471 static void *uid_m_start(struct seq_file
*seq
, loff_t
*ppos
)
473 struct user_namespace
*ns
= seq
->private;
475 return m_start(seq
, ppos
, &ns
->uid_map
);
478 static void *gid_m_start(struct seq_file
*seq
, loff_t
*ppos
)
480 struct user_namespace
*ns
= seq
->private;
482 return m_start(seq
, ppos
, &ns
->gid_map
);
485 static void *projid_m_start(struct seq_file
*seq
, loff_t
*ppos
)
487 struct user_namespace
*ns
= seq
->private;
489 return m_start(seq
, ppos
, &ns
->projid_map
);
492 static void *m_next(struct seq_file
*seq
, void *v
, loff_t
*pos
)
495 return seq
->op
->start(seq
, pos
);
498 static void m_stop(struct seq_file
*seq
, void *v
)
503 struct seq_operations proc_uid_seq_operations
= {
504 .start
= uid_m_start
,
510 struct seq_operations proc_gid_seq_operations
= {
511 .start
= gid_m_start
,
517 struct seq_operations proc_projid_seq_operations
= {
518 .start
= projid_m_start
,
521 .show
= projid_m_show
,
524 static bool mappings_overlap(struct uid_gid_map
*new_map
, struct uid_gid_extent
*extent
)
526 u32 upper_first
, lower_first
, upper_last
, lower_last
;
529 upper_first
= extent
->first
;
530 lower_first
= extent
->lower_first
;
531 upper_last
= upper_first
+ extent
->count
- 1;
532 lower_last
= lower_first
+ extent
->count
- 1;
534 for (idx
= 0; idx
< new_map
->nr_extents
; idx
++) {
535 u32 prev_upper_first
, prev_lower_first
;
536 u32 prev_upper_last
, prev_lower_last
;
537 struct uid_gid_extent
*prev
;
539 prev
= &new_map
->extent
[idx
];
541 prev_upper_first
= prev
->first
;
542 prev_lower_first
= prev
->lower_first
;
543 prev_upper_last
= prev_upper_first
+ prev
->count
- 1;
544 prev_lower_last
= prev_lower_first
+ prev
->count
- 1;
546 /* Does the upper range intersect a previous extent? */
547 if ((prev_upper_first
<= upper_last
) &&
548 (prev_upper_last
>= upper_first
))
551 /* Does the lower range intersect a previous extent? */
552 if ((prev_lower_first
<= lower_last
) &&
553 (prev_lower_last
>= lower_first
))
560 static DEFINE_MUTEX(id_map_mutex
);
562 static ssize_t
map_write(struct file
*file
, const char __user
*buf
,
563 size_t count
, loff_t
*ppos
,
565 struct uid_gid_map
*map
,
566 struct uid_gid_map
*parent_map
)
568 struct seq_file
*seq
= file
->private_data
;
569 struct user_namespace
*ns
= seq
->private;
570 struct uid_gid_map new_map
;
572 struct uid_gid_extent
*extent
= NULL
;
573 unsigned long page
= 0;
574 char *kbuf
, *pos
, *next_line
;
575 ssize_t ret
= -EINVAL
;
578 * The id_map_mutex serializes all writes to any given map.
580 * Any map is only ever written once.
582 * An id map fits within 1 cache line on most architectures.
584 * On read nothing needs to be done unless you are on an
585 * architecture with a crazy cache coherency model like alpha.
587 * There is a one time data dependency between reading the
588 * count of the extents and the values of the extents. The
589 * desired behavior is to see the values of the extents that
590 * were written before the count of the extents.
592 * To achieve this smp_wmb() is used on guarantee the write
593 * order and smp_read_barrier_depends() is guaranteed that we
594 * don't have crazy architectures returning stale data.
597 mutex_lock(&id_map_mutex
);
600 /* Only allow one successful write to the map */
601 if (map
->nr_extents
!= 0)
604 /* Require the appropriate privilege CAP_SETUID or CAP_SETGID
605 * over the user namespace in order to set the id mapping.
607 if (cap_valid(cap_setid
) && !ns_capable(ns
, cap_setid
))
612 page
= __get_free_page(GFP_TEMPORARY
);
613 kbuf
= (char *) page
;
617 /* Only allow <= page size writes at the beginning of the file */
619 if ((*ppos
!= 0) || (count
>= PAGE_SIZE
))
622 /* Slurp in the user data */
624 if (copy_from_user(kbuf
, buf
, count
))
628 /* Parse the user data */
631 new_map
.nr_extents
= 0;
632 for (;pos
; pos
= next_line
) {
633 extent
= &new_map
.extent
[new_map
.nr_extents
];
635 /* Find the end of line and ensure I don't look past it */
636 next_line
= strchr(pos
, '\n');
640 if (*next_line
== '\0')
644 pos
= skip_spaces(pos
);
645 extent
->first
= simple_strtoul(pos
, &pos
, 10);
649 pos
= skip_spaces(pos
);
650 extent
->lower_first
= simple_strtoul(pos
, &pos
, 10);
654 pos
= skip_spaces(pos
);
655 extent
->count
= simple_strtoul(pos
, &pos
, 10);
656 if (*pos
&& !isspace(*pos
))
659 /* Verify there is not trailing junk on the line */
660 pos
= skip_spaces(pos
);
664 /* Verify we have been given valid starting values */
665 if ((extent
->first
== (u32
) -1) ||
666 (extent
->lower_first
== (u32
) -1 ))
669 /* Verify count is not zero and does not cause the extent to wrap */
670 if ((extent
->first
+ extent
->count
) <= extent
->first
)
672 if ((extent
->lower_first
+ extent
->count
) <= extent
->lower_first
)
675 /* Do the ranges in extent overlap any previous extents? */
676 if (mappings_overlap(&new_map
, extent
))
679 new_map
.nr_extents
++;
681 /* Fail if the file contains too many extents */
682 if ((new_map
.nr_extents
== UID_GID_MAP_MAX_EXTENTS
) &&
686 /* Be very certaint the new map actually exists */
687 if (new_map
.nr_extents
== 0)
691 /* Validate the user is allowed to use user id's mapped to. */
692 if (!new_idmap_permitted(ns
, cap_setid
, &new_map
))
695 /* Map the lower ids from the parent user namespace to the
696 * kernel global id space.
698 for (idx
= 0; idx
< new_map
.nr_extents
; idx
++) {
700 extent
= &new_map
.extent
[idx
];
702 lower_first
= map_id_range_down(parent_map
,
706 /* Fail if we can not map the specified extent to
707 * the kernel global id space.
709 if (lower_first
== (u32
) -1)
712 extent
->lower_first
= lower_first
;
715 /* Install the map */
716 memcpy(map
->extent
, new_map
.extent
,
717 new_map
.nr_extents
*sizeof(new_map
.extent
[0]));
719 map
->nr_extents
= new_map
.nr_extents
;
724 mutex_unlock(&id_map_mutex
);
730 ssize_t
proc_uid_map_write(struct file
*file
, const char __user
*buf
, size_t size
, loff_t
*ppos
)
732 struct seq_file
*seq
= file
->private_data
;
733 struct user_namespace
*ns
= seq
->private;
734 struct user_namespace
*seq_ns
= seq_user_ns(seq
);
739 if ((seq_ns
!= ns
) && (seq_ns
!= ns
->parent
))
742 return map_write(file
, buf
, size
, ppos
, CAP_SETUID
,
743 &ns
->uid_map
, &ns
->parent
->uid_map
);
746 ssize_t
proc_gid_map_write(struct file
*file
, const char __user
*buf
, size_t size
, loff_t
*ppos
)
748 struct seq_file
*seq
= file
->private_data
;
749 struct user_namespace
*ns
= seq
->private;
750 struct user_namespace
*seq_ns
= seq_user_ns(seq
);
755 if ((seq_ns
!= ns
) && (seq_ns
!= ns
->parent
))
758 return map_write(file
, buf
, size
, ppos
, CAP_SETGID
,
759 &ns
->gid_map
, &ns
->parent
->gid_map
);
762 ssize_t
proc_projid_map_write(struct file
*file
, const char __user
*buf
, size_t size
, loff_t
*ppos
)
764 struct seq_file
*seq
= file
->private_data
;
765 struct user_namespace
*ns
= seq
->private;
766 struct user_namespace
*seq_ns
= seq_user_ns(seq
);
771 if ((seq_ns
!= ns
) && (seq_ns
!= ns
->parent
))
774 /* Anyone can set any valid project id no capability needed */
775 return map_write(file
, buf
, size
, ppos
, -1,
776 &ns
->projid_map
, &ns
->parent
->projid_map
);
779 static bool new_idmap_permitted(struct user_namespace
*ns
, int cap_setid
,
780 struct uid_gid_map
*new_map
)
782 /* Allow mapping to your own filesystem ids */
783 if ((new_map
->nr_extents
== 1) && (new_map
->extent
[0].count
== 1)) {
784 u32 id
= new_map
->extent
[0].lower_first
;
785 if (cap_setid
== CAP_SETUID
) {
786 kuid_t uid
= make_kuid(ns
->parent
, id
);
787 if (uid_eq(uid
, current_fsuid()))
790 else if (cap_setid
== CAP_SETGID
) {
791 kgid_t gid
= make_kgid(ns
->parent
, id
);
792 if (gid_eq(gid
, current_fsgid()))
797 /* Allow anyone to set a mapping that doesn't require privilege */
798 if (!cap_valid(cap_setid
))
801 /* Allow the specified ids if we have the appropriate capability
802 * (CAP_SETUID or CAP_SETGID) over the parent user namespace.
804 if (ns_capable(ns
->parent
, cap_setid
))
810 static void *userns_get(struct task_struct
*task
)
812 struct user_namespace
*user_ns
;
815 user_ns
= get_user_ns(__task_cred(task
)->user_ns
);
821 static void userns_put(void *ns
)
826 static int userns_install(struct nsproxy
*nsproxy
, void *ns
)
828 struct user_namespace
*user_ns
= ns
;
831 /* Don't allow gaining capabilities by reentering
832 * the same user namespace.
834 if (user_ns
== current_user_ns())
837 /* Threaded processes may not enter a different user namespace */
838 if (atomic_read(¤t
->mm
->mm_users
) > 1)
841 if (current
->fs
->users
!= 1)
844 if (!ns_capable(user_ns
, CAP_SYS_ADMIN
))
847 cred
= prepare_creds();
851 put_user_ns(cred
->user_ns
);
852 set_cred_user_ns(cred
, get_user_ns(user_ns
));
854 return commit_creds(cred
);
857 static unsigned int userns_inum(void *ns
)
859 struct user_namespace
*user_ns
= ns
;
860 return user_ns
->proc_inum
;
863 const struct proc_ns_operations userns_operations
= {
865 .type
= CLONE_NEWUSER
,
868 .install
= userns_install
,
872 static __init
int user_namespaces_init(void)
874 user_ns_cachep
= KMEM_CACHE(user_namespace
, SLAB_PANIC
);
877 module_init(user_namespaces_init
);