blob: 06083885b21e85314e3a196d13c7822dcc7c6e9d [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/namespace.c
3 *
4 * (C) Copyright Al Viro 2000, 2001
5 * Released under GPL v2.
6 *
7 * Based on code from fs/super.c, copyright Linus Torvalds and others.
8 * Heavily rewritten.
9 */
10
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/syscalls.h>
12#include <linux/slab.h>
13#include <linux/sched.h>
14#include <linux/smp_lock.h>
15#include <linux/init.h>
Randy Dunlap15a67dd2006-09-29 01:58:57 -070016#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/quotaops.h>
18#include <linux/acct.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080019#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/module.h>
Andrew Mortonf20a9ea2006-08-14 22:43:23 -070021#include <linux/sysfs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/seq_file.h>
Kirill Korotaev6b3286e2006-12-08 02:37:56 -080023#include <linux/mnt_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/namei.h>
25#include <linux/security.h>
26#include <linux/mount.h>
David Howells07f3f052006-09-30 20:52:18 +020027#include <linux/ramfs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <asm/uaccess.h>
29#include <asm/unistd.h>
Ram Pai07b20882005-11-07 17:19:07 -050030#include "pnode.h"
Adrian Bunk948730b2007-07-15 23:41:25 -070031#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
Linus Torvalds1da177e2005-04-16 15:20:36 -070033/* spinlock for vfsmount related operations, inplace of dcache_lock */
Al Viro5addc5d2005-11-07 17:15:49 -050034__cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
35
36static int event;
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
Eric Dumazetfa3536c2006-03-26 01:37:24 -080038static struct list_head *mount_hashtable __read_mostly;
Ravikiran G Thirumalai6c231b72005-09-06 15:17:45 -070039static int hash_mask __read_mostly, hash_bits __read_mostly;
Christoph Lametere18b8902006-12-06 20:33:20 -080040static struct kmem_cache *mnt_cache __read_mostly;
Ram Pai390c6842005-11-07 17:17:51 -050041static struct rw_semaphore namespace_sem;
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
Miklos Szeredif87fd4c2006-01-16 22:14:23 -080043/* /sys/fs */
44decl_subsys(fs, NULL, NULL);
45EXPORT_SYMBOL_GPL(fs_subsys);
46
Linus Torvalds1da177e2005-04-16 15:20:36 -070047static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
48{
Ram Paib58fed82005-11-07 17:16:09 -050049 unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
50 tmp += ((unsigned long)dentry / L1_CACHE_BYTES);
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 tmp = tmp + (tmp >> hash_bits);
52 return tmp & hash_mask;
53}
54
55struct vfsmount *alloc_vfsmnt(const char *name)
56{
Robert P. J. Dayc3762222007-02-10 01:45:03 -080057 struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 if (mnt) {
Ram Paib58fed82005-11-07 17:16:09 -050059 atomic_set(&mnt->mnt_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 INIT_LIST_HEAD(&mnt->mnt_hash);
61 INIT_LIST_HEAD(&mnt->mnt_child);
62 INIT_LIST_HEAD(&mnt->mnt_mounts);
63 INIT_LIST_HEAD(&mnt->mnt_list);
Miklos Szeredi55e700b2005-07-07 17:57:30 -070064 INIT_LIST_HEAD(&mnt->mnt_expire);
Ram Pai03e06e62005-11-07 17:19:33 -050065 INIT_LIST_HEAD(&mnt->mnt_share);
Ram Paia58b0eb2005-11-07 17:20:48 -050066 INIT_LIST_HEAD(&mnt->mnt_slave_list);
67 INIT_LIST_HEAD(&mnt->mnt_slave);
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 if (name) {
Ram Paib58fed82005-11-07 17:16:09 -050069 int size = strlen(name) + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 char *newname = kmalloc(size, GFP_KERNEL);
71 if (newname) {
72 memcpy(newname, name, size);
73 mnt->mnt_devname = newname;
74 }
75 }
76 }
77 return mnt;
78}
79
David Howells454e2392006-06-23 02:02:57 -070080int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
81{
82 mnt->mnt_sb = sb;
83 mnt->mnt_root = dget(sb->s_root);
84 return 0;
85}
86
87EXPORT_SYMBOL(simple_set_mnt);
88
Linus Torvalds1da177e2005-04-16 15:20:36 -070089void free_vfsmnt(struct vfsmount *mnt)
90{
91 kfree(mnt->mnt_devname);
92 kmem_cache_free(mnt_cache, mnt);
93}
94
95/*
Ram Paia05964f2005-11-07 17:20:17 -050096 * find the first or last mount at @dentry on vfsmount @mnt depending on
97 * @dir. If @dir is set return the first mount else return the last mount.
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 */
Ram Paia05964f2005-11-07 17:20:17 -050099struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry,
100 int dir)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101{
Ram Paib58fed82005-11-07 17:16:09 -0500102 struct list_head *head = mount_hashtable + hash(mnt, dentry);
103 struct list_head *tmp = head;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 struct vfsmount *p, *found = NULL;
105
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 for (;;) {
Ram Paia05964f2005-11-07 17:20:17 -0500107 tmp = dir ? tmp->next : tmp->prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 p = NULL;
109 if (tmp == head)
110 break;
111 p = list_entry(tmp, struct vfsmount, mnt_hash);
112 if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) {
Ram Paia05964f2005-11-07 17:20:17 -0500113 found = p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 break;
115 }
116 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 return found;
118}
119
Ram Paia05964f2005-11-07 17:20:17 -0500120/*
121 * lookup_mnt increments the ref count before returning
122 * the vfsmount struct.
123 */
124struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
125{
126 struct vfsmount *child_mnt;
127 spin_lock(&vfsmount_lock);
128 if ((child_mnt = __lookup_mnt(mnt, dentry, 1)))
129 mntget(child_mnt);
130 spin_unlock(&vfsmount_lock);
131 return child_mnt;
132}
133
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134static inline int check_mnt(struct vfsmount *mnt)
135{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800136 return mnt->mnt_ns == current->nsproxy->mnt_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137}
138
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800139static void touch_mnt_namespace(struct mnt_namespace *ns)
Al Viro5addc5d2005-11-07 17:15:49 -0500140{
141 if (ns) {
142 ns->event = ++event;
143 wake_up_interruptible(&ns->poll);
144 }
145}
146
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800147static void __touch_mnt_namespace(struct mnt_namespace *ns)
Al Viro5addc5d2005-11-07 17:15:49 -0500148{
149 if (ns && ns->event != event) {
150 ns->event = event;
151 wake_up_interruptible(&ns->poll);
152 }
153}
154
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd)
156{
157 old_nd->dentry = mnt->mnt_mountpoint;
158 old_nd->mnt = mnt->mnt_parent;
159 mnt->mnt_parent = mnt;
160 mnt->mnt_mountpoint = mnt->mnt_root;
161 list_del_init(&mnt->mnt_child);
162 list_del_init(&mnt->mnt_hash);
163 old_nd->dentry->d_mounted--;
164}
165
Ram Paib90fa9a2005-11-07 17:19:50 -0500166void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
167 struct vfsmount *child_mnt)
168{
169 child_mnt->mnt_parent = mntget(mnt);
170 child_mnt->mnt_mountpoint = dget(dentry);
171 dentry->d_mounted++;
172}
173
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd)
175{
Ram Paib90fa9a2005-11-07 17:19:50 -0500176 mnt_set_mountpoint(nd->mnt, nd->dentry, mnt);
177 list_add_tail(&mnt->mnt_hash, mount_hashtable +
178 hash(nd->mnt, nd->dentry));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts);
Ram Paib90fa9a2005-11-07 17:19:50 -0500180}
181
182/*
183 * the caller must hold vfsmount_lock
184 */
185static void commit_tree(struct vfsmount *mnt)
186{
187 struct vfsmount *parent = mnt->mnt_parent;
188 struct vfsmount *m;
189 LIST_HEAD(head);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800190 struct mnt_namespace *n = parent->mnt_ns;
Ram Paib90fa9a2005-11-07 17:19:50 -0500191
192 BUG_ON(parent == mnt);
193
194 list_add_tail(&head, &mnt->mnt_list);
195 list_for_each_entry(m, &head, mnt_list)
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800196 m->mnt_ns = n;
Ram Paib90fa9a2005-11-07 17:19:50 -0500197 list_splice(&head, n->list.prev);
198
199 list_add_tail(&mnt->mnt_hash, mount_hashtable +
200 hash(parent, mnt->mnt_mountpoint));
201 list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800202 touch_mnt_namespace(n);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203}
204
205static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root)
206{
207 struct list_head *next = p->mnt_mounts.next;
208 if (next == &p->mnt_mounts) {
209 while (1) {
210 if (p == root)
211 return NULL;
212 next = p->mnt_child.next;
213 if (next != &p->mnt_parent->mnt_mounts)
214 break;
215 p = p->mnt_parent;
216 }
217 }
218 return list_entry(next, struct vfsmount, mnt_child);
219}
220
Ram Pai9676f0c2005-11-07 17:21:20 -0500221static struct vfsmount *skip_mnt_tree(struct vfsmount *p)
222{
223 struct list_head *prev = p->mnt_mounts.prev;
224 while (prev != &p->mnt_mounts) {
225 p = list_entry(prev, struct vfsmount, mnt_child);
226 prev = p->mnt_mounts.prev;
227 }
228 return p;
229}
230
Ram Pai36341f62005-11-07 17:17:22 -0500231static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
232 int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233{
234 struct super_block *sb = old->mnt_sb;
235 struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
236
237 if (mnt) {
238 mnt->mnt_flags = old->mnt_flags;
239 atomic_inc(&sb->s_active);
240 mnt->mnt_sb = sb;
241 mnt->mnt_root = dget(root);
242 mnt->mnt_mountpoint = mnt->mnt_root;
243 mnt->mnt_parent = mnt;
Ram Paib90fa9a2005-11-07 17:19:50 -0500244
Ram Pai5afe0022005-11-07 17:21:01 -0500245 if (flag & CL_SLAVE) {
246 list_add(&mnt->mnt_slave, &old->mnt_slave_list);
247 mnt->mnt_master = old;
248 CLEAR_MNT_SHARED(mnt);
Al Viro8aec0802007-06-07 12:20:32 -0400249 } else if (!(flag & CL_PRIVATE)) {
Ram Pai5afe0022005-11-07 17:21:01 -0500250 if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
251 list_add(&mnt->mnt_share, &old->mnt_share);
252 if (IS_MNT_SLAVE(old))
253 list_add(&mnt->mnt_slave, &old->mnt_slave);
254 mnt->mnt_master = old->mnt_master;
255 }
Ram Paib90fa9a2005-11-07 17:19:50 -0500256 if (flag & CL_MAKE_SHARED)
257 set_mnt_shared(mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
259 /* stick the duplicate mount on the same expiry list
260 * as the original if that was on one */
Ram Pai36341f62005-11-07 17:17:22 -0500261 if (flag & CL_EXPIRE) {
262 spin_lock(&vfsmount_lock);
263 if (!list_empty(&old->mnt_expire))
264 list_add(&mnt->mnt_expire, &old->mnt_expire);
265 spin_unlock(&vfsmount_lock);
266 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 }
268 return mnt;
269}
270
Al Viro7b7b1ac2005-11-07 17:13:39 -0500271static inline void __mntput(struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272{
273 struct super_block *sb = mnt->mnt_sb;
274 dput(mnt->mnt_root);
275 free_vfsmnt(mnt);
276 deactivate_super(sb);
277}
278
Al Viro7b7b1ac2005-11-07 17:13:39 -0500279void mntput_no_expire(struct vfsmount *mnt)
280{
281repeat:
282 if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) {
283 if (likely(!mnt->mnt_pinned)) {
284 spin_unlock(&vfsmount_lock);
285 __mntput(mnt);
286 return;
287 }
288 atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count);
289 mnt->mnt_pinned = 0;
290 spin_unlock(&vfsmount_lock);
291 acct_auto_close_mnt(mnt);
292 security_sb_umount_close(mnt);
293 goto repeat;
294 }
295}
296
297EXPORT_SYMBOL(mntput_no_expire);
298
299void mnt_pin(struct vfsmount *mnt)
300{
301 spin_lock(&vfsmount_lock);
302 mnt->mnt_pinned++;
303 spin_unlock(&vfsmount_lock);
304}
305
306EXPORT_SYMBOL(mnt_pin);
307
308void mnt_unpin(struct vfsmount *mnt)
309{
310 spin_lock(&vfsmount_lock);
311 if (mnt->mnt_pinned) {
312 atomic_inc(&mnt->mnt_count);
313 mnt->mnt_pinned--;
314 }
315 spin_unlock(&vfsmount_lock);
316}
317
318EXPORT_SYMBOL(mnt_unpin);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319
320/* iterator */
321static void *m_start(struct seq_file *m, loff_t *pos)
322{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800323 struct mnt_namespace *n = m->private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324
Ram Pai390c6842005-11-07 17:17:51 -0500325 down_read(&namespace_sem);
Pavel Emelianovb0765fb2007-07-15 23:39:55 -0700326 return seq_list_start(&n->list, *pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327}
328
329static void *m_next(struct seq_file *m, void *v, loff_t *pos)
330{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800331 struct mnt_namespace *n = m->private;
Pavel Emelianovb0765fb2007-07-15 23:39:55 -0700332
333 return seq_list_next(v, &n->list, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334}
335
336static void m_stop(struct seq_file *m, void *v)
337{
Ram Pai390c6842005-11-07 17:17:51 -0500338 up_read(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339}
340
341static inline void mangle(struct seq_file *m, const char *s)
342{
343 seq_escape(m, s, " \t\n\\");
344}
345
346static int show_vfsmnt(struct seq_file *m, void *v)
347{
Pavel Emelianovb0765fb2007-07-15 23:39:55 -0700348 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 int err = 0;
350 static struct proc_fs_info {
351 int flag;
352 char *str;
353 } fs_info[] = {
354 { MS_SYNCHRONOUS, ",sync" },
355 { MS_DIRSYNC, ",dirsync" },
356 { MS_MANDLOCK, ",mand" },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 { 0, NULL }
358 };
359 static struct proc_fs_info mnt_info[] = {
360 { MNT_NOSUID, ",nosuid" },
361 { MNT_NODEV, ",nodev" },
362 { MNT_NOEXEC, ",noexec" },
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -0800363 { MNT_NOATIME, ",noatime" },
364 { MNT_NODIRATIME, ",nodiratime" },
Valerie Henson47ae32d2006-12-13 00:34:34 -0800365 { MNT_RELATIME, ",relatime" },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 { 0, NULL }
367 };
368 struct proc_fs_info *fs_infop;
369
370 mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
371 seq_putc(m, ' ');
372 seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
373 seq_putc(m, ' ');
374 mangle(m, mnt->mnt_sb->s_type->name);
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -0700375 if (mnt->mnt_sb->s_subtype && mnt->mnt_sb->s_subtype[0]) {
376 seq_putc(m, '.');
377 mangle(m, mnt->mnt_sb->s_subtype);
378 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw");
380 for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
381 if (mnt->mnt_sb->s_flags & fs_infop->flag)
382 seq_puts(m, fs_infop->str);
383 }
384 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
385 if (mnt->mnt_flags & fs_infop->flag)
386 seq_puts(m, fs_infop->str);
387 }
388 if (mnt->mnt_sb->s_op->show_options)
389 err = mnt->mnt_sb->s_op->show_options(m, mnt);
390 seq_puts(m, " 0 0\n");
391 return err;
392}
393
394struct seq_operations mounts_op = {
395 .start = m_start,
396 .next = m_next,
397 .stop = m_stop,
398 .show = show_vfsmnt
399};
400
Chuck Leverb4629fe2006-03-20 13:44:12 -0500401static int show_vfsstat(struct seq_file *m, void *v)
402{
Pavel Emelianovb0765fb2007-07-15 23:39:55 -0700403 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
Chuck Leverb4629fe2006-03-20 13:44:12 -0500404 int err = 0;
405
406 /* device */
407 if (mnt->mnt_devname) {
408 seq_puts(m, "device ");
409 mangle(m, mnt->mnt_devname);
410 } else
411 seq_puts(m, "no device");
412
413 /* mount point */
414 seq_puts(m, " mounted on ");
415 seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
416 seq_putc(m, ' ');
417
418 /* file system type */
419 seq_puts(m, "with fstype ");
420 mangle(m, mnt->mnt_sb->s_type->name);
421
422 /* optional statistics */
423 if (mnt->mnt_sb->s_op->show_stats) {
424 seq_putc(m, ' ');
425 err = mnt->mnt_sb->s_op->show_stats(m, mnt);
426 }
427
428 seq_putc(m, '\n');
429 return err;
430}
431
432struct seq_operations mountstats_op = {
433 .start = m_start,
434 .next = m_next,
435 .stop = m_stop,
436 .show = show_vfsstat,
437};
438
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439/**
440 * may_umount_tree - check if a mount tree is busy
441 * @mnt: root of mount tree
442 *
443 * This is called to check if a tree of mounts has any
444 * open files, pwds, chroots or sub mounts that are
445 * busy.
446 */
447int may_umount_tree(struct vfsmount *mnt)
448{
Ram Pai36341f62005-11-07 17:17:22 -0500449 int actual_refs = 0;
450 int minimum_refs = 0;
451 struct vfsmount *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452
453 spin_lock(&vfsmount_lock);
Ram Pai36341f62005-11-07 17:17:22 -0500454 for (p = mnt; p; p = next_mnt(p, mnt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 actual_refs += atomic_read(&p->mnt_count);
456 minimum_refs += 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 }
458 spin_unlock(&vfsmount_lock);
459
460 if (actual_refs > minimum_refs)
Ian Kente3474a82006-03-27 01:14:51 -0800461 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462
Ian Kente3474a82006-03-27 01:14:51 -0800463 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464}
465
466EXPORT_SYMBOL(may_umount_tree);
467
468/**
469 * may_umount - check if a mount point is busy
470 * @mnt: root of mount
471 *
472 * This is called to check if a mount point has any
473 * open files, pwds, chroots or sub mounts. If the
474 * mount has sub mounts this will return busy
475 * regardless of whether the sub mounts are busy.
476 *
477 * Doesn't take quota and stuff into account. IOW, in some cases it will
478 * give false negatives. The main reason why it's here is that we need
479 * a non-destructive way to look for easily umountable filesystems.
480 */
481int may_umount(struct vfsmount *mnt)
482{
Ian Kente3474a82006-03-27 01:14:51 -0800483 int ret = 1;
Ram Paia05964f2005-11-07 17:20:17 -0500484 spin_lock(&vfsmount_lock);
485 if (propagate_mount_busy(mnt, 2))
Ian Kente3474a82006-03-27 01:14:51 -0800486 ret = 0;
Ram Paia05964f2005-11-07 17:20:17 -0500487 spin_unlock(&vfsmount_lock);
488 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489}
490
491EXPORT_SYMBOL(may_umount);
492
Ram Paib90fa9a2005-11-07 17:19:50 -0500493void release_mounts(struct list_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494{
Ram Pai70fbcdf2005-11-07 17:17:04 -0500495 struct vfsmount *mnt;
Miklos Szeredibf066c72006-01-08 01:03:19 -0800496 while (!list_empty(head)) {
Pavel Emelianovb5e61812007-05-08 00:30:19 -0700497 mnt = list_first_entry(head, struct vfsmount, mnt_hash);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500498 list_del_init(&mnt->mnt_hash);
499 if (mnt->mnt_parent != mnt) {
500 struct dentry *dentry;
501 struct vfsmount *m;
502 spin_lock(&vfsmount_lock);
503 dentry = mnt->mnt_mountpoint;
504 m = mnt->mnt_parent;
505 mnt->mnt_mountpoint = mnt->mnt_root;
506 mnt->mnt_parent = mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500508 dput(dentry);
509 mntput(m);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 }
511 mntput(mnt);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500512 }
513}
514
Ram Paia05964f2005-11-07 17:20:17 -0500515void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
Ram Pai70fbcdf2005-11-07 17:17:04 -0500516{
517 struct vfsmount *p;
518
Akinobu Mita1bfba4e2006-06-26 00:24:40 -0700519 for (p = mnt; p; p = next_mnt(p, mnt))
520 list_move(&p->mnt_hash, kill);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500521
Ram Paia05964f2005-11-07 17:20:17 -0500522 if (propagate)
523 propagate_umount(kill);
524
Ram Pai70fbcdf2005-11-07 17:17:04 -0500525 list_for_each_entry(p, kill, mnt_hash) {
526 list_del_init(&p->mnt_expire);
527 list_del_init(&p->mnt_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800528 __touch_mnt_namespace(p->mnt_ns);
529 p->mnt_ns = NULL;
Ram Pai70fbcdf2005-11-07 17:17:04 -0500530 list_del_init(&p->mnt_child);
531 if (p->mnt_parent != p)
Al Virof30ac312006-02-01 07:53:21 -0500532 p->mnt_mountpoint->d_mounted--;
Ram Paia05964f2005-11-07 17:20:17 -0500533 change_mnt_propagation(p, MS_PRIVATE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 }
535}
536
537static int do_umount(struct vfsmount *mnt, int flags)
538{
Ram Paib58fed82005-11-07 17:16:09 -0500539 struct super_block *sb = mnt->mnt_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 int retval;
Ram Pai70fbcdf2005-11-07 17:17:04 -0500541 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542
543 retval = security_sb_umount(mnt, flags);
544 if (retval)
545 return retval;
546
547 /*
548 * Allow userspace to request a mountpoint be expired rather than
549 * unmounting unconditionally. Unmount only happens if:
550 * (1) the mark is already set (the mark is cleared by mntput())
551 * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
552 */
553 if (flags & MNT_EXPIRE) {
554 if (mnt == current->fs->rootmnt ||
555 flags & (MNT_FORCE | MNT_DETACH))
556 return -EINVAL;
557
558 if (atomic_read(&mnt->mnt_count) != 2)
559 return -EBUSY;
560
561 if (!xchg(&mnt->mnt_expiry_mark, 1))
562 return -EAGAIN;
563 }
564
565 /*
566 * If we may have to abort operations to get out of this
567 * mount, and they will themselves hold resources we must
568 * allow the fs to do things. In the Unix tradition of
569 * 'Gee thats tricky lets do it in userspace' the umount_begin
570 * might fail to complete on the first run through as other tasks
571 * must return, and the like. Thats for the mount program to worry
572 * about for the moment.
573 */
574
575 lock_kernel();
Trond Myklebust8b512d92006-06-09 09:34:18 -0400576 if (sb->s_op->umount_begin)
577 sb->s_op->umount_begin(mnt, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 unlock_kernel();
579
580 /*
581 * No sense to grab the lock for this test, but test itself looks
582 * somewhat bogus. Suggestions for better replacement?
583 * Ho-hum... In principle, we might treat that as umount + switch
584 * to rootfs. GC would eventually take care of the old vfsmount.
585 * Actually it makes sense, especially if rootfs would contain a
586 * /reboot - static binary that would close all descriptors and
587 * call reboot(9). Then init(8) could umount root and exec /reboot.
588 */
589 if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) {
590 /*
591 * Special case for "unmounting" root ...
592 * we just try to remount it readonly.
593 */
594 down_write(&sb->s_umount);
595 if (!(sb->s_flags & MS_RDONLY)) {
596 lock_kernel();
597 DQUOT_OFF(sb);
598 retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
599 unlock_kernel();
600 }
601 up_write(&sb->s_umount);
602 return retval;
603 }
604
Ram Pai390c6842005-11-07 17:17:51 -0500605 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 spin_lock(&vfsmount_lock);
Al Viro5addc5d2005-11-07 17:15:49 -0500607 event++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 retval = -EBUSY;
Ram Paia05964f2005-11-07 17:20:17 -0500610 if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 if (!list_empty(&mnt->mnt_list))
Ram Paia05964f2005-11-07 17:20:17 -0500612 umount_tree(mnt, 1, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613 retval = 0;
614 }
615 spin_unlock(&vfsmount_lock);
616 if (retval)
617 security_sb_umount_busy(mnt);
Ram Pai390c6842005-11-07 17:17:51 -0500618 up_write(&namespace_sem);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500619 release_mounts(&umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 return retval;
621}
622
623/*
624 * Now umount can handle mount points as well as block devices.
625 * This is important for filesystems which use unnamed block devices.
626 *
627 * We now support a flag for forced unmount like the other 'big iron'
628 * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
629 */
630
631asmlinkage long sys_umount(char __user * name, int flags)
632{
633 struct nameidata nd;
634 int retval;
635
636 retval = __user_walk(name, LOOKUP_FOLLOW, &nd);
637 if (retval)
638 goto out;
639 retval = -EINVAL;
640 if (nd.dentry != nd.mnt->mnt_root)
641 goto dput_and_out;
642 if (!check_mnt(nd.mnt))
643 goto dput_and_out;
644
645 retval = -EPERM;
646 if (!capable(CAP_SYS_ADMIN))
647 goto dput_and_out;
648
649 retval = do_umount(nd.mnt, flags);
650dput_and_out:
651 path_release_on_umount(&nd);
652out:
653 return retval;
654}
655
656#ifdef __ARCH_WANT_SYS_OLDUMOUNT
657
658/*
Ram Paib58fed82005-11-07 17:16:09 -0500659 * The 2.0 compatible umount. No flags.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661asmlinkage long sys_oldumount(char __user * name)
662{
Ram Paib58fed82005-11-07 17:16:09 -0500663 return sys_umount(name, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664}
665
666#endif
667
668static int mount_is_safe(struct nameidata *nd)
669{
670 if (capable(CAP_SYS_ADMIN))
671 return 0;
672 return -EPERM;
673#ifdef notyet
674 if (S_ISLNK(nd->dentry->d_inode->i_mode))
675 return -EPERM;
676 if (nd->dentry->d_inode->i_mode & S_ISVTX) {
677 if (current->uid != nd->dentry->d_inode->i_uid)
678 return -EPERM;
679 }
Christoph Hellwige4543ed2005-11-08 21:35:04 -0800680 if (vfs_permission(nd, MAY_WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 return -EPERM;
682 return 0;
683#endif
684}
685
Ram Paib58fed82005-11-07 17:16:09 -0500686static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687{
688 while (1) {
689 if (d == dentry)
690 return 1;
691 if (d == NULL || d == d->d_parent)
692 return 0;
693 d = d->d_parent;
694 }
695}
696
Ram Paib90fa9a2005-11-07 17:19:50 -0500697struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
Ram Pai36341f62005-11-07 17:17:22 -0500698 int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699{
700 struct vfsmount *res, *p, *q, *r, *s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701 struct nameidata nd;
702
Ram Pai9676f0c2005-11-07 17:21:20 -0500703 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
704 return NULL;
705
Ram Pai36341f62005-11-07 17:17:22 -0500706 res = q = clone_mnt(mnt, dentry, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707 if (!q)
708 goto Enomem;
709 q->mnt_mountpoint = mnt->mnt_mountpoint;
710
711 p = mnt;
Domen Puncerfdadd652005-09-10 00:27:07 -0700712 list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713 if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry))
714 continue;
715
716 for (s = r; s; s = next_mnt(s, r)) {
Ram Pai9676f0c2005-11-07 17:21:20 -0500717 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) {
718 s = skip_mnt_tree(s);
719 continue;
720 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 while (p != s->mnt_parent) {
722 p = p->mnt_parent;
723 q = q->mnt_parent;
724 }
725 p = s;
726 nd.mnt = q;
727 nd.dentry = p->mnt_mountpoint;
Ram Pai36341f62005-11-07 17:17:22 -0500728 q = clone_mnt(p, p->mnt_root, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 if (!q)
730 goto Enomem;
731 spin_lock(&vfsmount_lock);
732 list_add_tail(&q->mnt_list, &res->mnt_list);
733 attach_mnt(q, &nd);
734 spin_unlock(&vfsmount_lock);
735 }
736 }
737 return res;
Ram Paib58fed82005-11-07 17:16:09 -0500738Enomem:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 if (res) {
Ram Pai70fbcdf2005-11-07 17:17:04 -0500740 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -0500742 umount_tree(res, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500744 release_mounts(&umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 }
746 return NULL;
747}
748
Al Viro8aec0802007-06-07 12:20:32 -0400749struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry)
750{
751 struct vfsmount *tree;
752 down_read(&namespace_sem);
753 tree = copy_tree(mnt, dentry, CL_COPY_ALL | CL_PRIVATE);
754 up_read(&namespace_sem);
755 return tree;
756}
757
758void drop_collected_mounts(struct vfsmount *mnt)
759{
760 LIST_HEAD(umount_list);
761 down_read(&namespace_sem);
762 spin_lock(&vfsmount_lock);
763 umount_tree(mnt, 0, &umount_list);
764 spin_unlock(&vfsmount_lock);
765 up_read(&namespace_sem);
766 release_mounts(&umount_list);
767}
768
Ram Paib90fa9a2005-11-07 17:19:50 -0500769/*
770 * @source_mnt : mount tree to be attached
Ram Pai21444402005-11-07 17:20:03 -0500771 * @nd : place the mount tree @source_mnt is attached
772 * @parent_nd : if non-null, detach the source_mnt from its parent and
773 * store the parent mount and mountpoint dentry.
774 * (done when source_mnt is moved)
Ram Paib90fa9a2005-11-07 17:19:50 -0500775 *
776 * NOTE: in the table below explains the semantics when a source mount
777 * of a given type is attached to a destination mount of a given type.
Ram Pai9676f0c2005-11-07 17:21:20 -0500778 * ---------------------------------------------------------------------------
779 * | BIND MOUNT OPERATION |
780 * |**************************************************************************
781 * | source-->| shared | private | slave | unbindable |
782 * | dest | | | | |
783 * | | | | | | |
784 * | v | | | | |
785 * |**************************************************************************
786 * | shared | shared (++) | shared (+) | shared(+++)| invalid |
787 * | | | | | |
788 * |non-shared| shared (+) | private | slave (*) | invalid |
789 * ***************************************************************************
Ram Paib90fa9a2005-11-07 17:19:50 -0500790 * A bind operation clones the source mount and mounts the clone on the
791 * destination mount.
792 *
793 * (++) the cloned mount is propagated to all the mounts in the propagation
794 * tree of the destination mount and the cloned mount is added to
795 * the peer group of the source mount.
796 * (+) the cloned mount is created under the destination mount and is marked
797 * as shared. The cloned mount is added to the peer group of the source
798 * mount.
Ram Pai5afe0022005-11-07 17:21:01 -0500799 * (+++) the mount is propagated to all the mounts in the propagation tree
800 * of the destination mount and the cloned mount is made slave
801 * of the same master as that of the source mount. The cloned mount
802 * is marked as 'shared and slave'.
803 * (*) the cloned mount is made a slave of the same master as that of the
804 * source mount.
805 *
Ram Pai9676f0c2005-11-07 17:21:20 -0500806 * ---------------------------------------------------------------------------
807 * | MOVE MOUNT OPERATION |
808 * |**************************************************************************
809 * | source-->| shared | private | slave | unbindable |
810 * | dest | | | | |
811 * | | | | | | |
812 * | v | | | | |
813 * |**************************************************************************
814 * | shared | shared (+) | shared (+) | shared(+++) | invalid |
815 * | | | | | |
816 * |non-shared| shared (+*) | private | slave (*) | unbindable |
817 * ***************************************************************************
Ram Pai5afe0022005-11-07 17:21:01 -0500818 *
819 * (+) the mount is moved to the destination. And is then propagated to
820 * all the mounts in the propagation tree of the destination mount.
Ram Pai21444402005-11-07 17:20:03 -0500821 * (+*) the mount is moved to the destination.
Ram Pai5afe0022005-11-07 17:21:01 -0500822 * (+++) the mount is moved to the destination and is then propagated to
823 * all the mounts belonging to the destination mount's propagation tree.
824 * the mount is marked as 'shared and slave'.
825 * (*) the mount continues to be a slave at the new location.
Ram Paib90fa9a2005-11-07 17:19:50 -0500826 *
827 * if the source mount is a tree, the operations explained above is
828 * applied to each mount in the tree.
829 * Must be called without spinlocks held, since this function can sleep
830 * in allocations.
831 */
832static int attach_recursive_mnt(struct vfsmount *source_mnt,
Ram Pai21444402005-11-07 17:20:03 -0500833 struct nameidata *nd, struct nameidata *parent_nd)
Ram Paib90fa9a2005-11-07 17:19:50 -0500834{
835 LIST_HEAD(tree_list);
836 struct vfsmount *dest_mnt = nd->mnt;
837 struct dentry *dest_dentry = nd->dentry;
838 struct vfsmount *child, *p;
839
840 if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list))
841 return -EINVAL;
842
843 if (IS_MNT_SHARED(dest_mnt)) {
844 for (p = source_mnt; p; p = next_mnt(p, source_mnt))
845 set_mnt_shared(p);
846 }
847
848 spin_lock(&vfsmount_lock);
Ram Pai21444402005-11-07 17:20:03 -0500849 if (parent_nd) {
850 detach_mnt(source_mnt, parent_nd);
851 attach_mnt(source_mnt, nd);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800852 touch_mnt_namespace(current->nsproxy->mnt_ns);
Ram Pai21444402005-11-07 17:20:03 -0500853 } else {
854 mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
855 commit_tree(source_mnt);
856 }
Ram Paib90fa9a2005-11-07 17:19:50 -0500857
858 list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
859 list_del_init(&child->mnt_hash);
860 commit_tree(child);
861 }
862 spin_unlock(&vfsmount_lock);
863 return 0;
864}
865
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
867{
868 int err;
869 if (mnt->mnt_sb->s_flags & MS_NOUSER)
870 return -EINVAL;
871
872 if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
873 S_ISDIR(mnt->mnt_root->d_inode->i_mode))
874 return -ENOTDIR;
875
876 err = -ENOENT;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800877 mutex_lock(&nd->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878 if (IS_DEADDIR(nd->dentry->d_inode))
879 goto out_unlock;
880
881 err = security_sb_check_sb(mnt, nd);
882 if (err)
883 goto out_unlock;
884
885 err = -ENOENT;
Ram Paib90fa9a2005-11-07 17:19:50 -0500886 if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry))
Ram Pai21444402005-11-07 17:20:03 -0500887 err = attach_recursive_mnt(mnt, nd, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888out_unlock:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800889 mutex_unlock(&nd->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890 if (!err)
891 security_sb_post_addmount(mnt, nd);
892 return err;
893}
894
895/*
Ram Pai07b20882005-11-07 17:19:07 -0500896 * recursively change the type of the mountpoint.
897 */
898static int do_change_type(struct nameidata *nd, int flag)
899{
900 struct vfsmount *m, *mnt = nd->mnt;
901 int recurse = flag & MS_REC;
902 int type = flag & ~MS_REC;
903
Miklos Szerediee6f9582007-05-08 00:30:40 -0700904 if (!capable(CAP_SYS_ADMIN))
905 return -EPERM;
906
Ram Pai07b20882005-11-07 17:19:07 -0500907 if (nd->dentry != nd->mnt->mnt_root)
908 return -EINVAL;
909
910 down_write(&namespace_sem);
911 spin_lock(&vfsmount_lock);
912 for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
913 change_mnt_propagation(m, type);
914 spin_unlock(&vfsmount_lock);
915 up_write(&namespace_sem);
916 return 0;
917}
918
919/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 * do loopback mount.
921 */
Andrew Mortoneee391a2006-05-15 09:44:30 -0700922static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923{
924 struct nameidata old_nd;
925 struct vfsmount *mnt = NULL;
926 int err = mount_is_safe(nd);
927 if (err)
928 return err;
929 if (!old_name || !*old_name)
930 return -EINVAL;
931 err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
932 if (err)
933 return err;
934
Ram Pai390c6842005-11-07 17:17:51 -0500935 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936 err = -EINVAL;
Ram Pai9676f0c2005-11-07 17:21:20 -0500937 if (IS_MNT_UNBINDABLE(old_nd.mnt))
938 goto out;
939
Al Viroccd48bc2005-11-07 17:15:04 -0500940 if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
941 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942
Al Viroccd48bc2005-11-07 17:15:04 -0500943 err = -ENOMEM;
944 if (recurse)
Ram Pai36341f62005-11-07 17:17:22 -0500945 mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0);
Al Viroccd48bc2005-11-07 17:15:04 -0500946 else
Ram Pai36341f62005-11-07 17:17:22 -0500947 mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0);
Al Viroccd48bc2005-11-07 17:15:04 -0500948
949 if (!mnt)
950 goto out;
951
Al Viroccd48bc2005-11-07 17:15:04 -0500952 err = graft_tree(mnt, nd);
953 if (err) {
Ram Pai70fbcdf2005-11-07 17:17:04 -0500954 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700955 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -0500956 umount_tree(mnt, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500958 release_mounts(&umount_list);
Ram Pai5b83d2c5c2005-11-07 17:16:29 -0500959 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960
Al Viroccd48bc2005-11-07 17:15:04 -0500961out:
Ram Pai390c6842005-11-07 17:17:51 -0500962 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963 path_release(&old_nd);
964 return err;
965}
966
967/*
968 * change filesystem flags. dir should be a physical root of filesystem.
969 * If you've mounted a non-root directory somewhere and want to do remount
970 * on it - tough luck.
971 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972static int do_remount(struct nameidata *nd, int flags, int mnt_flags,
973 void *data)
974{
975 int err;
Ram Paib58fed82005-11-07 17:16:09 -0500976 struct super_block *sb = nd->mnt->mnt_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977
978 if (!capable(CAP_SYS_ADMIN))
979 return -EPERM;
980
981 if (!check_mnt(nd->mnt))
982 return -EINVAL;
983
984 if (nd->dentry != nd->mnt->mnt_root)
985 return -EINVAL;
986
987 down_write(&sb->s_umount);
988 err = do_remount_sb(sb, flags, data, 0);
989 if (!err)
Ram Paib58fed82005-11-07 17:16:09 -0500990 nd->mnt->mnt_flags = mnt_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 up_write(&sb->s_umount);
992 if (!err)
993 security_sb_post_remount(nd->mnt, flags, data);
994 return err;
995}
996
Ram Pai9676f0c2005-11-07 17:21:20 -0500997static inline int tree_contains_unbindable(struct vfsmount *mnt)
998{
999 struct vfsmount *p;
1000 for (p = mnt; p; p = next_mnt(p, mnt)) {
1001 if (IS_MNT_UNBINDABLE(p))
1002 return 1;
1003 }
1004 return 0;
1005}
1006
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007static int do_move_mount(struct nameidata *nd, char *old_name)
1008{
1009 struct nameidata old_nd, parent_nd;
1010 struct vfsmount *p;
1011 int err = 0;
1012 if (!capable(CAP_SYS_ADMIN))
1013 return -EPERM;
1014 if (!old_name || !*old_name)
1015 return -EINVAL;
1016 err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
1017 if (err)
1018 return err;
1019
Ram Pai390c6842005-11-07 17:17:51 -05001020 down_write(&namespace_sem);
Ram Paib58fed82005-11-07 17:16:09 -05001021 while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 ;
1023 err = -EINVAL;
1024 if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
1025 goto out;
1026
1027 err = -ENOENT;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001028 mutex_lock(&nd->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 if (IS_DEADDIR(nd->dentry->d_inode))
1030 goto out1;
1031
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032 if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry))
Ram Pai21444402005-11-07 17:20:03 -05001033 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034
1035 err = -EINVAL;
1036 if (old_nd.dentry != old_nd.mnt->mnt_root)
Ram Pai21444402005-11-07 17:20:03 -05001037 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038
1039 if (old_nd.mnt == old_nd.mnt->mnt_parent)
Ram Pai21444402005-11-07 17:20:03 -05001040 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041
1042 if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
1043 S_ISDIR(old_nd.dentry->d_inode->i_mode))
Ram Pai21444402005-11-07 17:20:03 -05001044 goto out1;
1045 /*
1046 * Don't move a mount residing in a shared parent.
1047 */
1048 if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent))
1049 goto out1;
Ram Pai9676f0c2005-11-07 17:21:20 -05001050 /*
1051 * Don't move a mount tree containing unbindable mounts to a destination
1052 * mount which is shared.
1053 */
1054 if (IS_MNT_SHARED(nd->mnt) && tree_contains_unbindable(old_nd.mnt))
1055 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 err = -ELOOP;
Ram Paib58fed82005-11-07 17:16:09 -05001057 for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 if (p == old_nd.mnt)
Ram Pai21444402005-11-07 17:20:03 -05001059 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060
Ram Pai21444402005-11-07 17:20:03 -05001061 if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd)))
1062 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063
Ram Pai21444402005-11-07 17:20:03 -05001064 spin_lock(&vfsmount_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 /* if the mount is moved, it should no longer be expire
1066 * automatically */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001067 list_del_init(&old_nd.mnt->mnt_expire);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068 spin_unlock(&vfsmount_lock);
1069out1:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001070 mutex_unlock(&nd->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071out:
Ram Pai390c6842005-11-07 17:17:51 -05001072 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073 if (!err)
1074 path_release(&parent_nd);
1075 path_release(&old_nd);
1076 return err;
1077}
1078
1079/*
1080 * create a new mount for userspace and request it to be added into the
1081 * namespace's tree
1082 */
1083static int do_new_mount(struct nameidata *nd, char *type, int flags,
1084 int mnt_flags, char *name, void *data)
1085{
1086 struct vfsmount *mnt;
1087
1088 if (!type || !memchr(type, 0, PAGE_SIZE))
1089 return -EINVAL;
1090
1091 /* we need capabilities... */
1092 if (!capable(CAP_SYS_ADMIN))
1093 return -EPERM;
1094
1095 mnt = do_kern_mount(type, flags, name, data);
1096 if (IS_ERR(mnt))
1097 return PTR_ERR(mnt);
1098
1099 return do_add_mount(mnt, nd, mnt_flags, NULL);
1100}
1101
1102/*
1103 * add a mount into a namespace's mount tree
1104 * - provide the option of adding the new mount to an expiration list
1105 */
1106int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
1107 int mnt_flags, struct list_head *fslist)
1108{
1109 int err;
1110
Ram Pai390c6842005-11-07 17:17:51 -05001111 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112 /* Something was mounted here while we slept */
Ram Paib58fed82005-11-07 17:16:09 -05001113 while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114 ;
1115 err = -EINVAL;
1116 if (!check_mnt(nd->mnt))
1117 goto unlock;
1118
1119 /* Refuse the same filesystem on the same mount point */
1120 err = -EBUSY;
1121 if (nd->mnt->mnt_sb == newmnt->mnt_sb &&
1122 nd->mnt->mnt_root == nd->dentry)
1123 goto unlock;
1124
1125 err = -EINVAL;
1126 if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
1127 goto unlock;
1128
1129 newmnt->mnt_flags = mnt_flags;
Ram Pai5b83d2c5c2005-11-07 17:16:29 -05001130 if ((err = graft_tree(newmnt, nd)))
1131 goto unlock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132
Ram Pai5b83d2c5c2005-11-07 17:16:29 -05001133 if (fslist) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 /* add to the specified expiration list */
1135 spin_lock(&vfsmount_lock);
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001136 list_add_tail(&newmnt->mnt_expire, fslist);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 spin_unlock(&vfsmount_lock);
1138 }
Ram Pai390c6842005-11-07 17:17:51 -05001139 up_write(&namespace_sem);
Ram Pai5b83d2c5c2005-11-07 17:16:29 -05001140 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141
1142unlock:
Ram Pai390c6842005-11-07 17:17:51 -05001143 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144 mntput(newmnt);
1145 return err;
1146}
1147
1148EXPORT_SYMBOL_GPL(do_add_mount);
1149
Ram Pai70fbcdf2005-11-07 17:17:04 -05001150static void expire_mount(struct vfsmount *mnt, struct list_head *mounts,
1151 struct list_head *umounts)
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001152{
1153 spin_lock(&vfsmount_lock);
1154
1155 /*
Miklos Szeredied42c872005-07-07 17:57:26 -07001156 * Check if mount is still attached, if not, let whoever holds it deal
1157 * with the sucker
1158 */
1159 if (mnt->mnt_parent == mnt) {
1160 spin_unlock(&vfsmount_lock);
1161 return;
1162 }
1163
1164 /*
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001165 * Check that it is still dead: the count should now be 2 - as
1166 * contributed by the vfsmount parent and the mntget above
1167 */
Ram Paia05964f2005-11-07 17:20:17 -05001168 if (!propagate_mount_busy(mnt, 2)) {
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001169 /* delete from the namespace */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001170 touch_mnt_namespace(mnt->mnt_ns);
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001171 list_del_init(&mnt->mnt_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001172 mnt->mnt_ns = NULL;
Ram Paia05964f2005-11-07 17:20:17 -05001173 umount_tree(mnt, 1, umounts);
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001174 spin_unlock(&vfsmount_lock);
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001175 } else {
1176 /*
1177 * Someone brought it back to life whilst we didn't have any
1178 * locks held so return it to the expiration list
1179 */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001180 list_add_tail(&mnt->mnt_expire, mounts);
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001181 spin_unlock(&vfsmount_lock);
1182 }
1183}
1184
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185/*
Trond Myklebust5528f9112006-06-09 09:34:17 -04001186 * go through the vfsmounts we've just consigned to the graveyard to
1187 * - check that they're still dead
1188 * - delete the vfsmount from the appropriate namespace under lock
1189 * - dispose of the corpse
1190 */
1191static void expire_mount_list(struct list_head *graveyard, struct list_head *mounts)
1192{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001193 struct mnt_namespace *ns;
Trond Myklebust5528f9112006-06-09 09:34:17 -04001194 struct vfsmount *mnt;
1195
1196 while (!list_empty(graveyard)) {
1197 LIST_HEAD(umounts);
Pavel Emelianovb5e61812007-05-08 00:30:19 -07001198 mnt = list_first_entry(graveyard, struct vfsmount, mnt_expire);
Trond Myklebust5528f9112006-06-09 09:34:17 -04001199 list_del_init(&mnt->mnt_expire);
1200
1201 /* don't do anything if the namespace is dead - all the
1202 * vfsmounts from it are going away anyway */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001203 ns = mnt->mnt_ns;
1204 if (!ns || !ns->root)
Trond Myklebust5528f9112006-06-09 09:34:17 -04001205 continue;
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001206 get_mnt_ns(ns);
Trond Myklebust5528f9112006-06-09 09:34:17 -04001207
1208 spin_unlock(&vfsmount_lock);
1209 down_write(&namespace_sem);
1210 expire_mount(mnt, mounts, &umounts);
1211 up_write(&namespace_sem);
1212 release_mounts(&umounts);
1213 mntput(mnt);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001214 put_mnt_ns(ns);
Trond Myklebust5528f9112006-06-09 09:34:17 -04001215 spin_lock(&vfsmount_lock);
1216 }
1217}
1218
1219/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 * process a list of expirable mountpoints with the intent of discarding any
1221 * mountpoints that aren't in use and haven't been touched since last we came
1222 * here
1223 */
1224void mark_mounts_for_expiry(struct list_head *mounts)
1225{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226 struct vfsmount *mnt, *next;
1227 LIST_HEAD(graveyard);
1228
1229 if (list_empty(mounts))
1230 return;
1231
1232 spin_lock(&vfsmount_lock);
1233
1234 /* extract from the expiration list every vfsmount that matches the
1235 * following criteria:
1236 * - only referenced by its parent vfsmount
1237 * - still marked for expiry (marked on the last call here; marks are
1238 * cleared by mntput())
1239 */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001240 list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241 if (!xchg(&mnt->mnt_expiry_mark, 1) ||
1242 atomic_read(&mnt->mnt_count) != 1)
1243 continue;
1244
1245 mntget(mnt);
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001246 list_move(&mnt->mnt_expire, &graveyard);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001247 }
1248
Trond Myklebust5528f9112006-06-09 09:34:17 -04001249 expire_mount_list(&graveyard, mounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250
1251 spin_unlock(&vfsmount_lock);
1252}
1253
1254EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
1255
1256/*
Trond Myklebust5528f9112006-06-09 09:34:17 -04001257 * Ripoff of 'select_parent()'
1258 *
1259 * search the list of submounts for a given mountpoint, and move any
1260 * shrinkable submounts to the 'graveyard' list.
1261 */
1262static int select_submounts(struct vfsmount *parent, struct list_head *graveyard)
1263{
1264 struct vfsmount *this_parent = parent;
1265 struct list_head *next;
1266 int found = 0;
1267
1268repeat:
1269 next = this_parent->mnt_mounts.next;
1270resume:
1271 while (next != &this_parent->mnt_mounts) {
1272 struct list_head *tmp = next;
1273 struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child);
1274
1275 next = tmp->next;
1276 if (!(mnt->mnt_flags & MNT_SHRINKABLE))
1277 continue;
1278 /*
1279 * Descend a level if the d_mounts list is non-empty.
1280 */
1281 if (!list_empty(&mnt->mnt_mounts)) {
1282 this_parent = mnt;
1283 goto repeat;
1284 }
1285
1286 if (!propagate_mount_busy(mnt, 1)) {
1287 mntget(mnt);
1288 list_move_tail(&mnt->mnt_expire, graveyard);
1289 found++;
1290 }
1291 }
1292 /*
1293 * All done at this level ... ascend and resume the search
1294 */
1295 if (this_parent != parent) {
1296 next = this_parent->mnt_child.next;
1297 this_parent = this_parent->mnt_parent;
1298 goto resume;
1299 }
1300 return found;
1301}
1302
1303/*
1304 * process a list of expirable mountpoints with the intent of discarding any
1305 * submounts of a specific parent mountpoint
1306 */
1307void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts)
1308{
1309 LIST_HEAD(graveyard);
1310 int found;
1311
1312 spin_lock(&vfsmount_lock);
1313
1314 /* extract submounts of 'mountpoint' from the expiration list */
1315 while ((found = select_submounts(mountpoint, &graveyard)) != 0)
1316 expire_mount_list(&graveyard, mounts);
1317
1318 spin_unlock(&vfsmount_lock);
1319}
1320
1321EXPORT_SYMBOL_GPL(shrink_submounts);
1322
1323/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324 * Some copy_from_user() implementations do not return the exact number of
1325 * bytes remaining to copy on a fault. But copy_mount_options() requires that.
1326 * Note that this function differs from copy_from_user() in that it will oops
1327 * on bad values of `to', rather than returning a short copy.
1328 */
Ram Paib58fed82005-11-07 17:16:09 -05001329static long exact_copy_from_user(void *to, const void __user * from,
1330 unsigned long n)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331{
1332 char *t = to;
1333 const char __user *f = from;
1334 char c;
1335
1336 if (!access_ok(VERIFY_READ, from, n))
1337 return n;
1338
1339 while (n) {
1340 if (__get_user(c, f)) {
1341 memset(t, 0, n);
1342 break;
1343 }
1344 *t++ = c;
1345 f++;
1346 n--;
1347 }
1348 return n;
1349}
1350
Ram Paib58fed82005-11-07 17:16:09 -05001351int copy_mount_options(const void __user * data, unsigned long *where)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352{
1353 int i;
1354 unsigned long page;
1355 unsigned long size;
Ram Paib58fed82005-11-07 17:16:09 -05001356
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 *where = 0;
1358 if (!data)
1359 return 0;
1360
1361 if (!(page = __get_free_page(GFP_KERNEL)))
1362 return -ENOMEM;
1363
1364 /* We only care that *some* data at the address the user
1365 * gave us is valid. Just in case, we'll zero
1366 * the remainder of the page.
1367 */
1368 /* copy_from_user cannot cross TASK_SIZE ! */
1369 size = TASK_SIZE - (unsigned long)data;
1370 if (size > PAGE_SIZE)
1371 size = PAGE_SIZE;
1372
1373 i = size - exact_copy_from_user((void *)page, data, size);
1374 if (!i) {
Ram Paib58fed82005-11-07 17:16:09 -05001375 free_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 return -EFAULT;
1377 }
1378 if (i != PAGE_SIZE)
1379 memset((char *)page + i, 0, PAGE_SIZE - i);
1380 *where = page;
1381 return 0;
1382}
1383
1384/*
1385 * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
1386 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
1387 *
1388 * data is a (void *) that can point to any structure up to
1389 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
1390 * information (or be NULL).
1391 *
1392 * Pre-0.97 versions of mount() didn't have a flags word.
1393 * When the flags word was introduced its top half was required
1394 * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
1395 * Therefore, if this magic number is present, it carries no information
1396 * and must be discarded.
1397 */
Ram Paib58fed82005-11-07 17:16:09 -05001398long do_mount(char *dev_name, char *dir_name, char *type_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 unsigned long flags, void *data_page)
1400{
1401 struct nameidata nd;
1402 int retval = 0;
1403 int mnt_flags = 0;
1404
1405 /* Discard magic */
1406 if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
1407 flags &= ~MS_MGC_MSK;
1408
1409 /* Basic sanity checks */
1410
1411 if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
1412 return -EINVAL;
1413 if (dev_name && !memchr(dev_name, 0, PAGE_SIZE))
1414 return -EINVAL;
1415
1416 if (data_page)
1417 ((char *)data_page)[PAGE_SIZE - 1] = 0;
1418
1419 /* Separate the per-mountpoint flags */
1420 if (flags & MS_NOSUID)
1421 mnt_flags |= MNT_NOSUID;
1422 if (flags & MS_NODEV)
1423 mnt_flags |= MNT_NODEV;
1424 if (flags & MS_NOEXEC)
1425 mnt_flags |= MNT_NOEXEC;
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -08001426 if (flags & MS_NOATIME)
1427 mnt_flags |= MNT_NOATIME;
1428 if (flags & MS_NODIRATIME)
1429 mnt_flags |= MNT_NODIRATIME;
Valerie Henson47ae32d2006-12-13 00:34:34 -08001430 if (flags & MS_RELATIME)
1431 mnt_flags |= MNT_RELATIME;
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -08001432
1433 flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001434 MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435
1436 /* ... and get the mountpoint */
1437 retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
1438 if (retval)
1439 return retval;
1440
1441 retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page);
1442 if (retval)
1443 goto dput_out;
1444
1445 if (flags & MS_REMOUNT)
1446 retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags,
1447 data_page);
1448 else if (flags & MS_BIND)
Andrew Mortoneee391a2006-05-15 09:44:30 -07001449 retval = do_loopback(&nd, dev_name, flags & MS_REC);
Ram Pai9676f0c2005-11-07 17:21:20 -05001450 else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
Ram Pai07b20882005-11-07 17:19:07 -05001451 retval = do_change_type(&nd, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 else if (flags & MS_MOVE)
1453 retval = do_move_mount(&nd, dev_name);
1454 else
1455 retval = do_new_mount(&nd, type_page, flags, mnt_flags,
1456 dev_name, data_page);
1457dput_out:
1458 path_release(&nd);
1459 return retval;
1460}
1461
JANAK DESAI741a2952006-02-07 12:59:00 -08001462/*
1463 * Allocate a new namespace structure and populate it with contents
1464 * copied from the namespace of the passed in task structure.
1465 */
Badari Pulavartye3222c42007-05-08 00:25:21 -07001466static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001467 struct fs_struct *fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001469 struct mnt_namespace *new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 struct vfsmount *p, *q;
1472
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001473 new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474 if (!new_ns)
Cedric Le Goater467e9f42007-07-15 23:41:06 -07001475 return ERR_PTR(-ENOMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476
1477 atomic_set(&new_ns->count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478 INIT_LIST_HEAD(&new_ns->list);
Al Viro5addc5d2005-11-07 17:15:49 -05001479 init_waitqueue_head(&new_ns->poll);
1480 new_ns->event = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001481
Ram Pai390c6842005-11-07 17:17:51 -05001482 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483 /* First pass: copy the tree topology */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001484 new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root,
Ram Pai9676f0c2005-11-07 17:21:20 -05001485 CL_COPY_ALL | CL_EXPIRE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 if (!new_ns->root) {
Ram Pai390c6842005-11-07 17:17:51 -05001487 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488 kfree(new_ns);
Cedric Le Goater467e9f42007-07-15 23:41:06 -07001489 return ERR_PTR(-ENOMEM);;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 }
1491 spin_lock(&vfsmount_lock);
1492 list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
1493 spin_unlock(&vfsmount_lock);
1494
1495 /*
1496 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
1497 * as belonging to new namespace. We have already acquired a private
1498 * fs_struct, so tsk->fs->lock is not needed.
1499 */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001500 p = mnt_ns->root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001501 q = new_ns->root;
1502 while (p) {
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001503 q->mnt_ns = new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504 if (fs) {
1505 if (p == fs->rootmnt) {
1506 rootmnt = p;
1507 fs->rootmnt = mntget(q);
1508 }
1509 if (p == fs->pwdmnt) {
1510 pwdmnt = p;
1511 fs->pwdmnt = mntget(q);
1512 }
1513 if (p == fs->altrootmnt) {
1514 altrootmnt = p;
1515 fs->altrootmnt = mntget(q);
1516 }
1517 }
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001518 p = next_mnt(p, mnt_ns->root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519 q = next_mnt(q, new_ns->root);
1520 }
Ram Pai390c6842005-11-07 17:17:51 -05001521 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523 if (rootmnt)
1524 mntput(rootmnt);
1525 if (pwdmnt)
1526 mntput(pwdmnt);
1527 if (altrootmnt)
1528 mntput(altrootmnt);
1529
JANAK DESAI741a2952006-02-07 12:59:00 -08001530 return new_ns;
1531}
1532
Eric W. Biederman213dd262007-07-15 23:41:15 -07001533struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
Badari Pulavartye3222c42007-05-08 00:25:21 -07001534 struct fs_struct *new_fs)
JANAK DESAI741a2952006-02-07 12:59:00 -08001535{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001536 struct mnt_namespace *new_ns;
JANAK DESAI741a2952006-02-07 12:59:00 -08001537
Badari Pulavartye3222c42007-05-08 00:25:21 -07001538 BUG_ON(!ns);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001539 get_mnt_ns(ns);
JANAK DESAI741a2952006-02-07 12:59:00 -08001540
1541 if (!(flags & CLONE_NEWNS))
Badari Pulavartye3222c42007-05-08 00:25:21 -07001542 return ns;
JANAK DESAI741a2952006-02-07 12:59:00 -08001543
Badari Pulavartye3222c42007-05-08 00:25:21 -07001544 new_ns = dup_mnt_ns(ns, new_fs);
JANAK DESAI741a2952006-02-07 12:59:00 -08001545
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001546 put_mnt_ns(ns);
Badari Pulavartye3222c42007-05-08 00:25:21 -07001547 return new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548}
1549
1550asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name,
1551 char __user * type, unsigned long flags,
1552 void __user * data)
1553{
1554 int retval;
1555 unsigned long data_page;
1556 unsigned long type_page;
1557 unsigned long dev_page;
1558 char *dir_page;
1559
Ram Paib58fed82005-11-07 17:16:09 -05001560 retval = copy_mount_options(type, &type_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561 if (retval < 0)
1562 return retval;
1563
1564 dir_page = getname(dir_name);
1565 retval = PTR_ERR(dir_page);
1566 if (IS_ERR(dir_page))
1567 goto out1;
1568
Ram Paib58fed82005-11-07 17:16:09 -05001569 retval = copy_mount_options(dev_name, &dev_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570 if (retval < 0)
1571 goto out2;
1572
Ram Paib58fed82005-11-07 17:16:09 -05001573 retval = copy_mount_options(data, &data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 if (retval < 0)
1575 goto out3;
1576
1577 lock_kernel();
Ram Paib58fed82005-11-07 17:16:09 -05001578 retval = do_mount((char *)dev_page, dir_page, (char *)type_page,
1579 flags, (void *)data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001580 unlock_kernel();
1581 free_page(data_page);
1582
1583out3:
1584 free_page(dev_page);
1585out2:
1586 putname(dir_page);
1587out1:
1588 free_page(type_page);
1589 return retval;
1590}
1591
1592/*
1593 * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
1594 * It can block. Requires the big lock held.
1595 */
1596void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt,
1597 struct dentry *dentry)
1598{
1599 struct dentry *old_root;
1600 struct vfsmount *old_rootmnt;
1601 write_lock(&fs->lock);
1602 old_root = fs->root;
1603 old_rootmnt = fs->rootmnt;
1604 fs->rootmnt = mntget(mnt);
1605 fs->root = dget(dentry);
1606 write_unlock(&fs->lock);
1607 if (old_root) {
1608 dput(old_root);
1609 mntput(old_rootmnt);
1610 }
1611}
1612
1613/*
1614 * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
1615 * It can block. Requires the big lock held.
1616 */
1617void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt,
1618 struct dentry *dentry)
1619{
1620 struct dentry *old_pwd;
1621 struct vfsmount *old_pwdmnt;
1622
1623 write_lock(&fs->lock);
1624 old_pwd = fs->pwd;
1625 old_pwdmnt = fs->pwdmnt;
1626 fs->pwdmnt = mntget(mnt);
1627 fs->pwd = dget(dentry);
1628 write_unlock(&fs->lock);
1629
1630 if (old_pwd) {
1631 dput(old_pwd);
1632 mntput(old_pwdmnt);
1633 }
1634}
1635
1636static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
1637{
1638 struct task_struct *g, *p;
1639 struct fs_struct *fs;
1640
1641 read_lock(&tasklist_lock);
1642 do_each_thread(g, p) {
1643 task_lock(p);
1644 fs = p->fs;
1645 if (fs) {
1646 atomic_inc(&fs->count);
1647 task_unlock(p);
Ram Paib58fed82005-11-07 17:16:09 -05001648 if (fs->root == old_nd->dentry
1649 && fs->rootmnt == old_nd->mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 set_fs_root(fs, new_nd->mnt, new_nd->dentry);
Ram Paib58fed82005-11-07 17:16:09 -05001651 if (fs->pwd == old_nd->dentry
1652 && fs->pwdmnt == old_nd->mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001653 set_fs_pwd(fs, new_nd->mnt, new_nd->dentry);
1654 put_fs_struct(fs);
1655 } else
1656 task_unlock(p);
1657 } while_each_thread(g, p);
1658 read_unlock(&tasklist_lock);
1659}
1660
1661/*
1662 * pivot_root Semantics:
1663 * Moves the root file system of the current process to the directory put_old,
1664 * makes new_root as the new root file system of the current process, and sets
1665 * root/cwd of all processes which had them on the current root to new_root.
1666 *
1667 * Restrictions:
1668 * The new_root and put_old must be directories, and must not be on the
1669 * same file system as the current process root. The put_old must be
1670 * underneath new_root, i.e. adding a non-zero number of /.. to the string
1671 * pointed to by put_old must yield the same directory as new_root. No other
1672 * file system may be mounted on put_old. After all, new_root is a mountpoint.
1673 *
Neil Brown4a0d11f2006-01-08 01:03:18 -08001674 * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
1675 * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
1676 * in this situation.
1677 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678 * Notes:
1679 * - we don't move root/cwd if they are not at the root (reason: if something
1680 * cared enough to change them, it's probably wrong to force them elsewhere)
1681 * - it's okay to pick a root that isn't the root of a file system, e.g.
1682 * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
1683 * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
1684 * first.
1685 */
Ram Paib58fed82005-11-07 17:16:09 -05001686asmlinkage long sys_pivot_root(const char __user * new_root,
1687 const char __user * put_old)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688{
1689 struct vfsmount *tmp;
1690 struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd;
1691 int error;
1692
1693 if (!capable(CAP_SYS_ADMIN))
1694 return -EPERM;
1695
1696 lock_kernel();
1697
Ram Paib58fed82005-11-07 17:16:09 -05001698 error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
1699 &new_nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001700 if (error)
1701 goto out0;
1702 error = -EINVAL;
1703 if (!check_mnt(new_nd.mnt))
1704 goto out1;
1705
Ram Paib58fed82005-11-07 17:16:09 -05001706 error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707 if (error)
1708 goto out1;
1709
1710 error = security_sb_pivotroot(&old_nd, &new_nd);
1711 if (error) {
1712 path_release(&old_nd);
1713 goto out1;
1714 }
1715
1716 read_lock(&current->fs->lock);
1717 user_nd.mnt = mntget(current->fs->rootmnt);
1718 user_nd.dentry = dget(current->fs->root);
1719 read_unlock(&current->fs->lock);
Ram Pai390c6842005-11-07 17:17:51 -05001720 down_write(&namespace_sem);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001721 mutex_lock(&old_nd.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722 error = -EINVAL;
Ram Pai21444402005-11-07 17:20:03 -05001723 if (IS_MNT_SHARED(old_nd.mnt) ||
1724 IS_MNT_SHARED(new_nd.mnt->mnt_parent) ||
1725 IS_MNT_SHARED(user_nd.mnt->mnt_parent))
1726 goto out2;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727 if (!check_mnt(user_nd.mnt))
1728 goto out2;
1729 error = -ENOENT;
1730 if (IS_DEADDIR(new_nd.dentry->d_inode))
1731 goto out2;
1732 if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry))
1733 goto out2;
1734 if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry))
1735 goto out2;
1736 error = -EBUSY;
1737 if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt)
1738 goto out2; /* loop, on the same file system */
1739 error = -EINVAL;
1740 if (user_nd.mnt->mnt_root != user_nd.dentry)
1741 goto out2; /* not a mountpoint */
Miklos Szeredi0bb6fcc2005-09-06 15:19:36 -07001742 if (user_nd.mnt->mnt_parent == user_nd.mnt)
1743 goto out2; /* not attached */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 if (new_nd.mnt->mnt_root != new_nd.dentry)
1745 goto out2; /* not a mountpoint */
Miklos Szeredi0bb6fcc2005-09-06 15:19:36 -07001746 if (new_nd.mnt->mnt_parent == new_nd.mnt)
1747 goto out2; /* not attached */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */
1749 spin_lock(&vfsmount_lock);
1750 if (tmp != new_nd.mnt) {
1751 for (;;) {
1752 if (tmp->mnt_parent == tmp)
1753 goto out3; /* already mounted on put_old */
1754 if (tmp->mnt_parent == new_nd.mnt)
1755 break;
1756 tmp = tmp->mnt_parent;
1757 }
1758 if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry))
1759 goto out3;
1760 } else if (!is_subdir(old_nd.dentry, new_nd.dentry))
1761 goto out3;
1762 detach_mnt(new_nd.mnt, &parent_nd);
1763 detach_mnt(user_nd.mnt, &root_parent);
1764 attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */
1765 attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001766 touch_mnt_namespace(current->nsproxy->mnt_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 spin_unlock(&vfsmount_lock);
1768 chroot_fs_refs(&user_nd, &new_nd);
1769 security_sb_post_pivotroot(&user_nd, &new_nd);
1770 error = 0;
1771 path_release(&root_parent);
1772 path_release(&parent_nd);
1773out2:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001774 mutex_unlock(&old_nd.dentry->d_inode->i_mutex);
Ram Pai390c6842005-11-07 17:17:51 -05001775 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001776 path_release(&user_nd);
1777 path_release(&old_nd);
1778out1:
1779 path_release(&new_nd);
1780out0:
1781 unlock_kernel();
1782 return error;
1783out3:
1784 spin_unlock(&vfsmount_lock);
1785 goto out2;
1786}
1787
1788static void __init init_mount_tree(void)
1789{
1790 struct vfsmount *mnt;
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001791 struct mnt_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792
1793 mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
1794 if (IS_ERR(mnt))
1795 panic("Can't create rootfs");
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001796 ns = kmalloc(sizeof(*ns), GFP_KERNEL);
1797 if (!ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798 panic("Can't allocate initial namespace");
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001799 atomic_set(&ns->count, 1);
1800 INIT_LIST_HEAD(&ns->list);
1801 init_waitqueue_head(&ns->poll);
1802 ns->event = 0;
1803 list_add(&mnt->mnt_list, &ns->list);
1804 ns->root = mnt;
1805 mnt->mnt_ns = ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001806
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001807 init_task.nsproxy->mnt_ns = ns;
1808 get_mnt_ns(ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001809
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001810 set_fs_pwd(current->fs, ns->root, ns->root->mnt_root);
1811 set_fs_root(current->fs, ns->root, ns->root->mnt_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001812}
1813
Denis Cheng74bf17c2007-10-16 23:26:30 -07001814void __init mnt_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815{
1816 struct list_head *d;
1817 unsigned int nr_hash;
1818 int i;
Randy Dunlap15a67dd2006-09-29 01:58:57 -07001819 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820
Ram Pai390c6842005-11-07 17:17:51 -05001821 init_rwsem(&namespace_sem);
1822
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823 mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
Paul Mundt20c2df82007-07-20 10:11:58 +09001824 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825
Ram Paib58fed82005-11-07 17:16:09 -05001826 mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827
1828 if (!mount_hashtable)
1829 panic("Failed to allocate mount hash table\n");
1830
1831 /*
1832 * Find the power-of-two list-heads that can fit into the allocation..
1833 * We don't guarantee that "sizeof(struct list_head)" is necessarily
1834 * a power-of-two.
1835 */
1836 nr_hash = PAGE_SIZE / sizeof(struct list_head);
1837 hash_bits = 0;
1838 do {
1839 hash_bits++;
1840 } while ((nr_hash >> hash_bits) != 0);
1841 hash_bits--;
1842
1843 /*
1844 * Re-calculate the actual number of entries and the mask
1845 * from the number of bits we can fit.
1846 */
1847 nr_hash = 1UL << hash_bits;
Ram Paib58fed82005-11-07 17:16:09 -05001848 hash_mask = nr_hash - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849
1850 printk("Mount-cache hash table entries: %d\n", nr_hash);
1851
1852 /* And initialize the newly allocated array */
1853 d = mount_hashtable;
1854 i = nr_hash;
1855 do {
1856 INIT_LIST_HEAD(d);
1857 d++;
1858 i--;
1859 } while (i);
Randy Dunlap15a67dd2006-09-29 01:58:57 -07001860 err = sysfs_init();
1861 if (err)
1862 printk(KERN_WARNING "%s: sysfs_init error: %d\n",
1863 __FUNCTION__, err);
1864 err = subsystem_register(&fs_subsys);
1865 if (err)
1866 printk(KERN_WARNING "%s: subsystem_register error: %d\n",
1867 __FUNCTION__, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868 init_rootfs();
1869 init_mount_tree();
1870}
1871
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001872void __put_mnt_ns(struct mnt_namespace *ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001874 struct vfsmount *root = ns->root;
Ram Pai70fbcdf2005-11-07 17:17:04 -05001875 LIST_HEAD(umount_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001876 ns->root = NULL;
Miklos Szeredi1ce88cf2005-07-07 17:57:24 -07001877 spin_unlock(&vfsmount_lock);
Ram Pai390c6842005-11-07 17:17:51 -05001878 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -05001880 umount_tree(root, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001881 spin_unlock(&vfsmount_lock);
Ram Pai390c6842005-11-07 17:17:51 -05001882 up_write(&namespace_sem);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001883 release_mounts(&umount_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001884 kfree(ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885}