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1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (c) 2025 Christian Brauner <[email protected]> */
3
4#include <linux/nstree.h>
5#include <linux/proc_ns.h>
6#include <linux/rculist.h>
7#include <linux/vfsdebug.h>
8#include <linux/syscalls.h>
9#include <linux/user_namespace.h>
10
11static __cacheline_aligned_in_smp DEFINE_SEQLOCK(ns_tree_lock);
12
13DEFINE_LOCK_GUARD_0(ns_tree_writer,
14 write_seqlock(&ns_tree_lock),
15 write_sequnlock(&ns_tree_lock))
16
17DEFINE_LOCK_GUARD_0(ns_tree_locked_reader,
18 read_seqlock_excl(&ns_tree_lock),
19 read_sequnlock_excl(&ns_tree_lock))
20
21static struct ns_tree_root ns_unified_root = { /* protected by ns_tree_lock */
22 .ns_rb = RB_ROOT,
23 .ns_list_head = LIST_HEAD_INIT(ns_unified_root.ns_list_head),
24};
25
26struct ns_tree_root mnt_ns_tree = {
27 .ns_rb = RB_ROOT,
28 .ns_list_head = LIST_HEAD_INIT(mnt_ns_tree.ns_list_head),
29};
30
31struct ns_tree_root net_ns_tree = {
32 .ns_rb = RB_ROOT,
33 .ns_list_head = LIST_HEAD_INIT(net_ns_tree.ns_list_head),
34};
35EXPORT_SYMBOL_GPL(net_ns_tree);
36
37struct ns_tree_root uts_ns_tree = {
38 .ns_rb = RB_ROOT,
39 .ns_list_head = LIST_HEAD_INIT(uts_ns_tree.ns_list_head),
40};
41
42struct ns_tree_root user_ns_tree = {
43 .ns_rb = RB_ROOT,
44 .ns_list_head = LIST_HEAD_INIT(user_ns_tree.ns_list_head),
45};
46
47struct ns_tree_root ipc_ns_tree = {
48 .ns_rb = RB_ROOT,
49 .ns_list_head = LIST_HEAD_INIT(ipc_ns_tree.ns_list_head),
50};
51
52struct ns_tree_root pid_ns_tree = {
53 .ns_rb = RB_ROOT,
54 .ns_list_head = LIST_HEAD_INIT(pid_ns_tree.ns_list_head),
55};
56
57struct ns_tree_root cgroup_ns_tree = {
58 .ns_rb = RB_ROOT,
59 .ns_list_head = LIST_HEAD_INIT(cgroup_ns_tree.ns_list_head),
60};
61
62struct ns_tree_root time_ns_tree = {
63 .ns_rb = RB_ROOT,
64 .ns_list_head = LIST_HEAD_INIT(time_ns_tree.ns_list_head),
65};
66
67/**
68 * ns_tree_node_init - Initialize a namespace tree node
69 * @node: The node to initialize
70 *
71 * Initializes both the rbtree node and list entry.
72 */
73void ns_tree_node_init(struct ns_tree_node *node)
74{
75 RB_CLEAR_NODE(&node->ns_node);
76 INIT_LIST_HEAD(&node->ns_list_entry);
77}
78
79/**
80 * ns_tree_root_init - Initialize a namespace tree root
81 * @root: The root to initialize
82 *
83 * Initializes both the rbtree root and list head.
84 */
85void ns_tree_root_init(struct ns_tree_root *root)
86{
87 root->ns_rb = RB_ROOT;
88 INIT_LIST_HEAD(&root->ns_list_head);
89}
90
91/**
92 * ns_tree_node_empty - Check if a namespace tree node is empty
93 * @node: The node to check
94 *
95 * Returns true if the node is not in any tree.
96 */
97bool ns_tree_node_empty(const struct ns_tree_node *node)
98{
99 return RB_EMPTY_NODE(&node->ns_node);
100}
101
102/**
103 * ns_tree_node_add - Add a node to a namespace tree
104 * @node: The node to add
105 * @root: The tree root to add to
106 * @cmp: Comparison function for rbtree insertion
107 *
108 * Adds the node to both the rbtree and the list, maintaining sorted order.
109 * The list is maintained in the same order as the rbtree to enable efficient
110 * iteration.
111 *
112 * Returns: NULL if insertion succeeded, existing node if duplicate found
113 */
114struct rb_node *ns_tree_node_add(struct ns_tree_node *node,
115 struct ns_tree_root *root,
116 int (*cmp)(struct rb_node *, const struct rb_node *))
117{
118 struct rb_node *ret, *prev;
119
120 /* Add to rbtree */
121 ret = rb_find_add_rcu(&node->ns_node, &root->ns_rb, cmp);
122
123 /* Add to list in sorted order */
124 prev = rb_prev(&node->ns_node);
125 if (!prev) {
126 /* No previous node, add at head */
127 list_add_rcu(&node->ns_list_entry, &root->ns_list_head);
128 } else {
129 /* Add after previous node */
130 struct ns_tree_node *prev_node;
131 prev_node = rb_entry(prev, struct ns_tree_node, ns_node);
132 list_add_rcu(&node->ns_list_entry, &prev_node->ns_list_entry);
133 }
134
135 return ret;
136}
137
138/**
139 * ns_tree_node_del - Remove a node from a namespace tree
140 * @node: The node to remove
141 * @root: The tree root to remove from
142 *
143 * Removes the node from both the rbtree and the list atomically.
144 */
145void ns_tree_node_del(struct ns_tree_node *node, struct ns_tree_root *root)
146{
147 rb_erase(&node->ns_node, &root->ns_rb);
148 RB_CLEAR_NODE(&node->ns_node);
149 list_bidir_del_rcu(&node->ns_list_entry);
150}
151
152static inline struct ns_common *node_to_ns(const struct rb_node *node)
153{
154 if (!node)
155 return NULL;
156 return rb_entry(node, struct ns_common, ns_tree_node.ns_node);
157}
158
159static inline struct ns_common *node_to_ns_unified(const struct rb_node *node)
160{
161 if (!node)
162 return NULL;
163 return rb_entry(node, struct ns_common, ns_unified_node.ns_node);
164}
165
166static inline struct ns_common *node_to_ns_owner(const struct rb_node *node)
167{
168 if (!node)
169 return NULL;
170 return rb_entry(node, struct ns_common, ns_owner_node.ns_node);
171}
172
173static int ns_id_cmp(u64 id_a, u64 id_b)
174{
175 if (id_a < id_b)
176 return -1;
177 if (id_a > id_b)
178 return 1;
179 return 0;
180}
181
182static int ns_cmp(struct rb_node *a, const struct rb_node *b)
183{
184 return ns_id_cmp(node_to_ns(a)->ns_id, node_to_ns(b)->ns_id);
185}
186
187static int ns_cmp_unified(struct rb_node *a, const struct rb_node *b)
188{
189 return ns_id_cmp(node_to_ns_unified(a)->ns_id, node_to_ns_unified(b)->ns_id);
190}
191
192static int ns_cmp_owner(struct rb_node *a, const struct rb_node *b)
193{
194 return ns_id_cmp(node_to_ns_owner(a)->ns_id, node_to_ns_owner(b)->ns_id);
195}
196
197void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree_root *ns_tree)
198{
199 struct rb_node *node;
200 const struct proc_ns_operations *ops = ns->ops;
201
202 VFS_WARN_ON_ONCE(!ns->ns_id);
203
204 guard(ns_tree_writer)();
205
206 /* Add to per-type tree and list */
207 node = ns_tree_node_add(&ns->ns_tree_node, ns_tree, ns_cmp);
208
209 /* Add to unified tree and list */
210 ns_tree_node_add(&ns->ns_unified_node, &ns_unified_root, ns_cmp_unified);
211
212 /* Add to owner's tree if applicable */
213 if (ops) {
214 struct user_namespace *user_ns;
215
216 VFS_WARN_ON_ONCE(!ops->owner);
217 user_ns = ops->owner(ns);
218 if (user_ns) {
219 struct ns_common *owner = &user_ns->ns;
220 VFS_WARN_ON_ONCE(owner->ns_type != CLONE_NEWUSER);
221
222 /* Insert into owner's tree and list */
223 ns_tree_node_add(&ns->ns_owner_node, &owner->ns_owner_root, ns_cmp_owner);
224 } else {
225 /* Only the initial user namespace doesn't have an owner. */
226 VFS_WARN_ON_ONCE(ns != to_ns_common(&init_user_ns));
227 }
228 }
229
230 VFS_WARN_ON_ONCE(node);
231}
232
233void __ns_tree_remove(struct ns_common *ns, struct ns_tree_root *ns_tree)
234{
235 const struct proc_ns_operations *ops = ns->ops;
236 struct user_namespace *user_ns;
237
238 VFS_WARN_ON_ONCE(ns_tree_node_empty(&ns->ns_tree_node));
239 VFS_WARN_ON_ONCE(list_empty(&ns->ns_tree_node.ns_list_entry));
240
241 write_seqlock(&ns_tree_lock);
242
243 /* Remove from per-type tree and list */
244 ns_tree_node_del(&ns->ns_tree_node, ns_tree);
245
246 /* Remove from unified tree and list */
247 ns_tree_node_del(&ns->ns_unified_node, &ns_unified_root);
248
249 /* Remove from owner's tree if applicable */
250 if (ops) {
251 user_ns = ops->owner(ns);
252 if (user_ns) {
253 struct ns_common *owner = &user_ns->ns;
254 ns_tree_node_del(&ns->ns_owner_node, &owner->ns_owner_root);
255 }
256 }
257
258 write_sequnlock(&ns_tree_lock);
259}
260EXPORT_SYMBOL_GPL(__ns_tree_remove);
261
262static int ns_find(const void *key, const struct rb_node *node)
263{
264 const u64 ns_id = *(u64 *)key;
265 const struct ns_common *ns = node_to_ns(node);
266
267 if (ns_id < ns->ns_id)
268 return -1;
269 if (ns_id > ns->ns_id)
270 return 1;
271 return 0;
272}
273
274static int ns_find_unified(const void *key, const struct rb_node *node)
275{
276 const u64 ns_id = *(u64 *)key;
277 const struct ns_common *ns = node_to_ns_unified(node);
278
279 if (ns_id < ns->ns_id)
280 return -1;
281 if (ns_id > ns->ns_id)
282 return 1;
283 return 0;
284}
285
286static struct ns_tree_root *ns_tree_from_type(int ns_type)
287{
288 switch (ns_type) {
289 case CLONE_NEWCGROUP:
290 return &cgroup_ns_tree;
291 case CLONE_NEWIPC:
292 return &ipc_ns_tree;
293 case CLONE_NEWNS:
294 return &mnt_ns_tree;
295 case CLONE_NEWNET:
296 return &net_ns_tree;
297 case CLONE_NEWPID:
298 return &pid_ns_tree;
299 case CLONE_NEWUSER:
300 return &user_ns_tree;
301 case CLONE_NEWUTS:
302 return &uts_ns_tree;
303 case CLONE_NEWTIME:
304 return &time_ns_tree;
305 }
306
307 return NULL;
308}
309
310static struct ns_common *__ns_unified_tree_lookup_rcu(u64 ns_id)
311{
312 struct rb_node *node;
313 unsigned int seq;
314
315 do {
316 seq = read_seqbegin(&ns_tree_lock);
317 node = rb_find_rcu(&ns_id, &ns_unified_root.ns_rb, ns_find_unified);
318 if (node)
319 break;
320 } while (read_seqretry(&ns_tree_lock, seq));
321
322 return node_to_ns_unified(node);
323}
324
325static struct ns_common *__ns_tree_lookup_rcu(u64 ns_id, int ns_type)
326{
327 struct ns_tree_root *ns_tree;
328 struct rb_node *node;
329 unsigned int seq;
330
331 ns_tree = ns_tree_from_type(ns_type);
332 if (!ns_tree)
333 return NULL;
334
335 do {
336 seq = read_seqbegin(&ns_tree_lock);
337 node = rb_find_rcu(&ns_id, &ns_tree->ns_rb, ns_find);
338 if (node)
339 break;
340 } while (read_seqretry(&ns_tree_lock, seq));
341
342 return node_to_ns(node);
343}
344
345struct ns_common *ns_tree_lookup_rcu(u64 ns_id, int ns_type)
346{
347 RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "suspicious ns_tree_lookup_rcu() usage");
348
349 if (ns_type)
350 return __ns_tree_lookup_rcu(ns_id, ns_type);
351
352 return __ns_unified_tree_lookup_rcu(ns_id);
353}
354
355/**
356 * __ns_tree_adjoined_rcu - find the next/previous namespace in the same
357 * tree
358 * @ns: namespace to start from
359 * @ns_tree: namespace tree to search in
360 * @previous: if true find the previous namespace, otherwise the next
361 *
362 * Find the next or previous namespace in the same tree as @ns. If
363 * there is no next/previous namespace, -ENOENT is returned.
364 */
365struct ns_common *__ns_tree_adjoined_rcu(struct ns_common *ns,
366 struct ns_tree_root *ns_tree, bool previous)
367{
368 struct list_head *list;
369
370 RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "suspicious ns_tree_adjoined_rcu() usage");
371
372 if (previous)
373 list = rcu_dereference(list_bidir_prev_rcu(&ns->ns_tree_node.ns_list_entry));
374 else
375 list = rcu_dereference(list_next_rcu(&ns->ns_tree_node.ns_list_entry));
376 if (list_is_head(list, &ns_tree->ns_list_head))
377 return ERR_PTR(-ENOENT);
378
379 return list_entry_rcu(list, struct ns_common, ns_tree_node.ns_list_entry);
380}
381
382/**
383 * __ns_tree_gen_id - generate a new namespace id
384 * @ns: namespace to generate id for
385 * @id: if non-zero, this is the initial namespace and this is a fixed id
386 *
387 * Generates a new namespace id and assigns it to the namespace. All
388 * namespaces types share the same id space and thus can be compared
389 * directly. IOW, when two ids of two namespace are equal, they are
390 * identical.
391 */
392u64 __ns_tree_gen_id(struct ns_common *ns, u64 id)
393{
394 static atomic64_t namespace_cookie = ATOMIC64_INIT(NS_LAST_INIT_ID + 1);
395
396 if (id)
397 ns->ns_id = id;
398 else
399 ns->ns_id = atomic64_inc_return(&namespace_cookie);
400 return ns->ns_id;
401}
402
403struct klistns {
404 u64 __user *uns_ids;
405 u32 nr_ns_ids;
406 u64 last_ns_id;
407 u64 user_ns_id;
408 u32 ns_type;
409 struct user_namespace *user_ns;
410 bool userns_capable;
411 struct ns_common *first_ns;
412};
413
414static void __free_klistns_free(const struct klistns *kls)
415{
416 if (kls->user_ns_id != LISTNS_CURRENT_USER)
417 put_user_ns(kls->user_ns);
418 if (kls->first_ns && kls->first_ns->ops)
419 kls->first_ns->ops->put(kls->first_ns);
420}
421
422#define NS_ALL (PID_NS | USER_NS | MNT_NS | UTS_NS | IPC_NS | NET_NS | CGROUP_NS | TIME_NS)
423
424static int copy_ns_id_req(const struct ns_id_req __user *req,
425 struct ns_id_req *kreq)
426{
427 int ret;
428 size_t usize;
429
430 BUILD_BUG_ON(sizeof(struct ns_id_req) != NS_ID_REQ_SIZE_VER0);
431
432 ret = get_user(usize, &req->size);
433 if (ret)
434 return -EFAULT;
435 if (unlikely(usize > PAGE_SIZE))
436 return -E2BIG;
437 if (unlikely(usize < NS_ID_REQ_SIZE_VER0))
438 return -EINVAL;
439 memset(kreq, 0, sizeof(*kreq));
440 ret = copy_struct_from_user(kreq, sizeof(*kreq), req, usize);
441 if (ret)
442 return ret;
443 if (kreq->spare != 0)
444 return -EINVAL;
445 if (kreq->ns_type & ~NS_ALL)
446 return -EOPNOTSUPP;
447 return 0;
448}
449
450static inline int prepare_klistns(struct klistns *kls, struct ns_id_req *kreq,
451 u64 __user *ns_ids, size_t nr_ns_ids)
452{
453 kls->last_ns_id = kreq->ns_id;
454 kls->user_ns_id = kreq->user_ns_id;
455 kls->nr_ns_ids = nr_ns_ids;
456 kls->ns_type = kreq->ns_type;
457 kls->uns_ids = ns_ids;
458 return 0;
459}
460
461/*
462 * Lookup a namespace owned by owner with id >= ns_id.
463 * Returns the namespace with the smallest id that is >= ns_id.
464 */
465static struct ns_common *lookup_ns_owner_at(u64 ns_id, struct ns_common *owner)
466{
467 struct ns_common *ret = NULL;
468 struct rb_node *node;
469
470 VFS_WARN_ON_ONCE(owner->ns_type != CLONE_NEWUSER);
471
472 guard(ns_tree_locked_reader)();
473
474 node = owner->ns_owner_root.ns_rb.rb_node;
475 while (node) {
476 struct ns_common *ns;
477
478 ns = node_to_ns_owner(node);
479 if (ns_id <= ns->ns_id) {
480 ret = ns;
481 if (ns_id == ns->ns_id)
482 break;
483 node = node->rb_left;
484 } else {
485 node = node->rb_right;
486 }
487 }
488
489 if (ret)
490 ret = ns_get_unless_inactive(ret);
491 return ret;
492}
493
494static struct ns_common *lookup_ns_id(u64 mnt_ns_id, int ns_type)
495{
496 struct ns_common *ns;
497
498 guard(rcu)();
499 ns = ns_tree_lookup_rcu(mnt_ns_id, ns_type);
500 if (!ns)
501 return NULL;
502
503 if (!ns_get_unless_inactive(ns))
504 return NULL;
505
506 return ns;
507}
508
509static inline bool __must_check ns_requested(const struct klistns *kls,
510 const struct ns_common *ns)
511{
512 return !kls->ns_type || (kls->ns_type & ns->ns_type);
513}
514
515static inline bool __must_check may_list_ns(const struct klistns *kls,
516 struct ns_common *ns)
517{
518 if (kls->user_ns && kls->userns_capable)
519 return true;
520 if (is_current_namespace(ns))
521 return true;
522 return may_see_all_namespaces();
523}
524
525static inline void ns_put(struct ns_common *ns)
526{
527 if (ns && ns->ops)
528 ns->ops->put(ns);
529}
530
531DEFINE_FREE(ns_put, struct ns_common *, if (!IS_ERR_OR_NULL(_T)) ns_put(_T))
532
533static inline struct ns_common *__must_check legitimize_ns(const struct klistns *kls,
534 struct ns_common *candidate)
535{
536 if (!ns_requested(kls, candidate))
537 return NULL;
538
539 if (!may_list_ns(kls, candidate))
540 return NULL;
541
542 return ns_get_unless_inactive(candidate);
543}
544
545static ssize_t do_listns_userns(struct klistns *kls)
546{
547 u64 __user *ns_ids = kls->uns_ids;
548 size_t nr_ns_ids = kls->nr_ns_ids;
549 struct ns_common *ns = NULL, *first_ns = NULL, *prev = NULL;
550 const struct list_head *head;
551 ssize_t ret;
552
553 VFS_WARN_ON_ONCE(!kls->user_ns_id);
554
555 if (kls->user_ns_id == LISTNS_CURRENT_USER)
556 ns = to_ns_common(current_user_ns());
557 else if (kls->user_ns_id)
558 ns = lookup_ns_id(kls->user_ns_id, CLONE_NEWUSER);
559 if (!ns)
560 return -EINVAL;
561 kls->user_ns = to_user_ns(ns);
562
563 /*
564 * Use the rbtree to find the first namespace we care about and
565 * then use it's list entry to iterate from there.
566 */
567 if (kls->last_ns_id) {
568 kls->first_ns = lookup_ns_owner_at(kls->last_ns_id + 1, ns);
569 if (!kls->first_ns)
570 return -ENOENT;
571 first_ns = kls->first_ns;
572 }
573
574 ret = 0;
575 head = &to_ns_common(kls->user_ns)->ns_owner_root.ns_list_head;
576 kls->userns_capable = may_see_all_namespaces();
577
578 rcu_read_lock();
579
580 if (!first_ns)
581 first_ns = list_entry_rcu(head->next, typeof(*first_ns), ns_owner_node.ns_list_entry);
582
583 ns = first_ns;
584 list_for_each_entry_from_rcu(ns, head, ns_owner_node.ns_list_entry) {
585 struct ns_common *valid;
586
587 if (!nr_ns_ids)
588 break;
589
590 valid = legitimize_ns(kls, ns);
591 if (!valid)
592 continue;
593
594 rcu_read_unlock();
595
596 ns_put(prev);
597 prev = valid;
598
599 if (put_user(valid->ns_id, ns_ids + ret)) {
600 ns_put(prev);
601 return -EFAULT;
602 }
603
604 nr_ns_ids--;
605 ret++;
606
607 rcu_read_lock();
608 }
609
610 rcu_read_unlock();
611 ns_put(prev);
612 return ret;
613}
614
615/*
616 * Lookup a namespace with id >= ns_id in either the unified tree or a type-specific tree.
617 * Returns the namespace with the smallest id that is >= ns_id.
618 */
619static struct ns_common *lookup_ns_id_at(u64 ns_id, int ns_type)
620{
621 struct ns_common *ret = NULL;
622 struct ns_tree_root *ns_tree = NULL;
623 struct rb_node *node;
624
625 if (ns_type) {
626 ns_tree = ns_tree_from_type(ns_type);
627 if (!ns_tree)
628 return NULL;
629 }
630
631 guard(ns_tree_locked_reader)();
632
633 if (ns_tree)
634 node = ns_tree->ns_rb.rb_node;
635 else
636 node = ns_unified_root.ns_rb.rb_node;
637
638 while (node) {
639 struct ns_common *ns;
640
641 if (ns_type)
642 ns = node_to_ns(node);
643 else
644 ns = node_to_ns_unified(node);
645
646 if (ns_id <= ns->ns_id) {
647 if (ns_type)
648 ret = node_to_ns(node);
649 else
650 ret = node_to_ns_unified(node);
651 if (ns_id == ns->ns_id)
652 break;
653 node = node->rb_left;
654 } else {
655 node = node->rb_right;
656 }
657 }
658
659 if (ret)
660 ret = ns_get_unless_inactive(ret);
661 return ret;
662}
663
664static inline struct ns_common *first_ns_common(const struct list_head *head,
665 struct ns_tree_root *ns_tree)
666{
667 if (ns_tree)
668 return list_entry_rcu(head->next, struct ns_common, ns_tree_node.ns_list_entry);
669 return list_entry_rcu(head->next, struct ns_common, ns_unified_node.ns_list_entry);
670}
671
672static inline struct ns_common *next_ns_common(struct ns_common *ns,
673 struct ns_tree_root *ns_tree)
674{
675 if (ns_tree)
676 return list_entry_rcu(ns->ns_tree_node.ns_list_entry.next, struct ns_common, ns_tree_node.ns_list_entry);
677 return list_entry_rcu(ns->ns_unified_node.ns_list_entry.next, struct ns_common, ns_unified_node.ns_list_entry);
678}
679
680static inline bool ns_common_is_head(struct ns_common *ns,
681 const struct list_head *head,
682 struct ns_tree_root *ns_tree)
683{
684 if (ns_tree)
685 return &ns->ns_tree_node.ns_list_entry == head;
686 return &ns->ns_unified_node.ns_list_entry == head;
687}
688
689static ssize_t do_listns(struct klistns *kls)
690{
691 u64 __user *ns_ids = kls->uns_ids;
692 size_t nr_ns_ids = kls->nr_ns_ids;
693 struct ns_common *ns, *first_ns = NULL, *prev = NULL;
694 struct ns_tree_root *ns_tree = NULL;
695 const struct list_head *head;
696 u32 ns_type;
697 ssize_t ret;
698
699 if (hweight32(kls->ns_type) == 1)
700 ns_type = kls->ns_type;
701 else
702 ns_type = 0;
703
704 if (ns_type) {
705 ns_tree = ns_tree_from_type(ns_type);
706 if (!ns_tree)
707 return -EINVAL;
708 }
709
710 if (kls->last_ns_id) {
711 kls->first_ns = lookup_ns_id_at(kls->last_ns_id + 1, ns_type);
712 if (!kls->first_ns)
713 return -ENOENT;
714 first_ns = kls->first_ns;
715 }
716
717 ret = 0;
718 if (ns_tree)
719 head = &ns_tree->ns_list_head;
720 else
721 head = &ns_unified_root.ns_list_head;
722
723 rcu_read_lock();
724
725 if (!first_ns)
726 first_ns = first_ns_common(head, ns_tree);
727
728 for (ns = first_ns; !ns_common_is_head(ns, head, ns_tree) && nr_ns_ids;
729 ns = next_ns_common(ns, ns_tree)) {
730 struct ns_common *valid;
731
732 valid = legitimize_ns(kls, ns);
733 if (!valid)
734 continue;
735
736 rcu_read_unlock();
737
738 ns_put(prev);
739 prev = valid;
740
741 if (put_user(valid->ns_id, ns_ids + ret)) {
742 ns_put(prev);
743 return -EFAULT;
744 }
745
746 nr_ns_ids--;
747 ret++;
748
749 rcu_read_lock();
750 }
751
752 rcu_read_unlock();
753 ns_put(prev);
754 return ret;
755}
756
757SYSCALL_DEFINE4(listns, const struct ns_id_req __user *, req,
758 u64 __user *, ns_ids, size_t, nr_ns_ids, unsigned int, flags)
759{
760 struct klistns klns __free(klistns_free) = {};
761 const size_t maxcount = 1000000;
762 struct ns_id_req kreq;
763 ssize_t ret;
764
765 if (flags)
766 return -EINVAL;
767
768 if (unlikely(nr_ns_ids > maxcount))
769 return -EOVERFLOW;
770
771 if (!access_ok(ns_ids, nr_ns_ids * sizeof(*ns_ids)))
772 return -EFAULT;
773
774 ret = copy_ns_id_req(req, &kreq);
775 if (ret)
776 return ret;
777
778 ret = prepare_klistns(&klns, &kreq, ns_ids, nr_ns_ids);
779 if (ret)
780 return ret;
781
782 if (kreq.user_ns_id)
783 return do_listns_userns(&klns);
784
785 return do_listns(&klns);
786}