blob: 5ef336c1103c2c4a4ecbb5c9bf96cf8923e15454 [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"
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
Linus Torvalds1da177e2005-04-16 15:20:36 -070032/* spinlock for vfsmount related operations, inplace of dcache_lock */
Al Viro5addc5d2005-11-07 17:15:49 -050033__cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
34
35static int event;
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
Eric Dumazetfa3536c2006-03-26 01:37:24 -080037static struct list_head *mount_hashtable __read_mostly;
Ravikiran G Thirumalai6c231b72005-09-06 15:17:45 -070038static int hash_mask __read_mostly, hash_bits __read_mostly;
Christoph Lametere18b8902006-12-06 20:33:20 -080039static struct kmem_cache *mnt_cache __read_mostly;
Ram Pai390c6842005-11-07 17:17:51 -050040static struct rw_semaphore namespace_sem;
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
Miklos Szeredif87fd4c2006-01-16 22:14:23 -080042/* /sys/fs */
43decl_subsys(fs, NULL, NULL);
44EXPORT_SYMBOL_GPL(fs_subsys);
45
Linus Torvalds1da177e2005-04-16 15:20:36 -070046static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
47{
Ram Paib58fed82005-11-07 17:16:09 -050048 unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
49 tmp += ((unsigned long)dentry / L1_CACHE_BYTES);
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 tmp = tmp + (tmp >> hash_bits);
51 return tmp & hash_mask;
52}
53
54struct vfsmount *alloc_vfsmnt(const char *name)
55{
Ram Paib58fed82005-11-07 17:16:09 -050056 struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 if (mnt) {
58 memset(mnt, 0, sizeof(struct vfsmount));
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);
249 } else {
250 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 struct list_head *p;
325 loff_t l = *pos;
326
Ram Pai390c6842005-11-07 17:17:51 -0500327 down_read(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 list_for_each(p, &n->list)
329 if (!l--)
330 return list_entry(p, struct vfsmount, mnt_list);
331 return NULL;
332}
333
334static void *m_next(struct seq_file *m, void *v, loff_t *pos)
335{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800336 struct mnt_namespace *n = m->private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 struct list_head *p = ((struct vfsmount *)v)->mnt_list.next;
338 (*pos)++;
Ram Paib58fed82005-11-07 17:16:09 -0500339 return p == &n->list ? NULL : list_entry(p, struct vfsmount, mnt_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340}
341
342static void m_stop(struct seq_file *m, void *v)
343{
Ram Pai390c6842005-11-07 17:17:51 -0500344 up_read(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345}
346
347static inline void mangle(struct seq_file *m, const char *s)
348{
349 seq_escape(m, s, " \t\n\\");
350}
351
352static int show_vfsmnt(struct seq_file *m, void *v)
353{
354 struct vfsmount *mnt = v;
355 int err = 0;
356 static struct proc_fs_info {
357 int flag;
358 char *str;
359 } fs_info[] = {
360 { MS_SYNCHRONOUS, ",sync" },
361 { MS_DIRSYNC, ",dirsync" },
362 { MS_MANDLOCK, ",mand" },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 { 0, NULL }
364 };
365 static struct proc_fs_info mnt_info[] = {
366 { MNT_NOSUID, ",nosuid" },
367 { MNT_NODEV, ",nodev" },
368 { MNT_NOEXEC, ",noexec" },
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -0800369 { MNT_NOATIME, ",noatime" },
370 { MNT_NODIRATIME, ",nodiratime" },
Valerie Henson47ae32d2006-12-13 00:34:34 -0800371 { MNT_RELATIME, ",relatime" },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 { 0, NULL }
373 };
374 struct proc_fs_info *fs_infop;
375
376 mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
377 seq_putc(m, ' ');
378 seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
379 seq_putc(m, ' ');
380 mangle(m, mnt->mnt_sb->s_type->name);
381 seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw");
382 for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
383 if (mnt->mnt_sb->s_flags & fs_infop->flag)
384 seq_puts(m, fs_infop->str);
385 }
386 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
387 if (mnt->mnt_flags & fs_infop->flag)
388 seq_puts(m, fs_infop->str);
389 }
390 if (mnt->mnt_sb->s_op->show_options)
391 err = mnt->mnt_sb->s_op->show_options(m, mnt);
392 seq_puts(m, " 0 0\n");
393 return err;
394}
395
396struct seq_operations mounts_op = {
397 .start = m_start,
398 .next = m_next,
399 .stop = m_stop,
400 .show = show_vfsmnt
401};
402
Chuck Leverb4629fe2006-03-20 13:44:12 -0500403static int show_vfsstat(struct seq_file *m, void *v)
404{
405 struct vfsmount *mnt = v;
406 int err = 0;
407
408 /* device */
409 if (mnt->mnt_devname) {
410 seq_puts(m, "device ");
411 mangle(m, mnt->mnt_devname);
412 } else
413 seq_puts(m, "no device");
414
415 /* mount point */
416 seq_puts(m, " mounted on ");
417 seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
418 seq_putc(m, ' ');
419
420 /* file system type */
421 seq_puts(m, "with fstype ");
422 mangle(m, mnt->mnt_sb->s_type->name);
423
424 /* optional statistics */
425 if (mnt->mnt_sb->s_op->show_stats) {
426 seq_putc(m, ' ');
427 err = mnt->mnt_sb->s_op->show_stats(m, mnt);
428 }
429
430 seq_putc(m, '\n');
431 return err;
432}
433
434struct seq_operations mountstats_op = {
435 .start = m_start,
436 .next = m_next,
437 .stop = m_stop,
438 .show = show_vfsstat,
439};
440
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441/**
442 * may_umount_tree - check if a mount tree is busy
443 * @mnt: root of mount tree
444 *
445 * This is called to check if a tree of mounts has any
446 * open files, pwds, chroots or sub mounts that are
447 * busy.
448 */
449int may_umount_tree(struct vfsmount *mnt)
450{
Ram Pai36341f62005-11-07 17:17:22 -0500451 int actual_refs = 0;
452 int minimum_refs = 0;
453 struct vfsmount *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454
455 spin_lock(&vfsmount_lock);
Ram Pai36341f62005-11-07 17:17:22 -0500456 for (p = mnt; p; p = next_mnt(p, mnt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 actual_refs += atomic_read(&p->mnt_count);
458 minimum_refs += 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 }
460 spin_unlock(&vfsmount_lock);
461
462 if (actual_refs > minimum_refs)
Ian Kente3474a82006-03-27 01:14:51 -0800463 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464
Ian Kente3474a82006-03-27 01:14:51 -0800465 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466}
467
468EXPORT_SYMBOL(may_umount_tree);
469
470/**
471 * may_umount - check if a mount point is busy
472 * @mnt: root of mount
473 *
474 * This is called to check if a mount point has any
475 * open files, pwds, chroots or sub mounts. If the
476 * mount has sub mounts this will return busy
477 * regardless of whether the sub mounts are busy.
478 *
479 * Doesn't take quota and stuff into account. IOW, in some cases it will
480 * give false negatives. The main reason why it's here is that we need
481 * a non-destructive way to look for easily umountable filesystems.
482 */
483int may_umount(struct vfsmount *mnt)
484{
Ian Kente3474a82006-03-27 01:14:51 -0800485 int ret = 1;
Ram Paia05964f2005-11-07 17:20:17 -0500486 spin_lock(&vfsmount_lock);
487 if (propagate_mount_busy(mnt, 2))
Ian Kente3474a82006-03-27 01:14:51 -0800488 ret = 0;
Ram Paia05964f2005-11-07 17:20:17 -0500489 spin_unlock(&vfsmount_lock);
490 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491}
492
493EXPORT_SYMBOL(may_umount);
494
Ram Paib90fa9a2005-11-07 17:19:50 -0500495void release_mounts(struct list_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496{
Ram Pai70fbcdf2005-11-07 17:17:04 -0500497 struct vfsmount *mnt;
Miklos Szeredibf066c72006-01-08 01:03:19 -0800498 while (!list_empty(head)) {
Ram Pai70fbcdf2005-11-07 17:17:04 -0500499 mnt = list_entry(head->next, struct vfsmount, mnt_hash);
500 list_del_init(&mnt->mnt_hash);
501 if (mnt->mnt_parent != mnt) {
502 struct dentry *dentry;
503 struct vfsmount *m;
504 spin_lock(&vfsmount_lock);
505 dentry = mnt->mnt_mountpoint;
506 m = mnt->mnt_parent;
507 mnt->mnt_mountpoint = mnt->mnt_root;
508 mnt->mnt_parent = mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500510 dput(dentry);
511 mntput(m);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 }
513 mntput(mnt);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500514 }
515}
516
Ram Paia05964f2005-11-07 17:20:17 -0500517void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
Ram Pai70fbcdf2005-11-07 17:17:04 -0500518{
519 struct vfsmount *p;
520
Akinobu Mita1bfba4e2006-06-26 00:24:40 -0700521 for (p = mnt; p; p = next_mnt(p, mnt))
522 list_move(&p->mnt_hash, kill);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500523
Ram Paia05964f2005-11-07 17:20:17 -0500524 if (propagate)
525 propagate_umount(kill);
526
Ram Pai70fbcdf2005-11-07 17:17:04 -0500527 list_for_each_entry(p, kill, mnt_hash) {
528 list_del_init(&p->mnt_expire);
529 list_del_init(&p->mnt_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800530 __touch_mnt_namespace(p->mnt_ns);
531 p->mnt_ns = NULL;
Ram Pai70fbcdf2005-11-07 17:17:04 -0500532 list_del_init(&p->mnt_child);
533 if (p->mnt_parent != p)
Al Virof30ac312006-02-01 07:53:21 -0500534 p->mnt_mountpoint->d_mounted--;
Ram Paia05964f2005-11-07 17:20:17 -0500535 change_mnt_propagation(p, MS_PRIVATE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 }
537}
538
539static int do_umount(struct vfsmount *mnt, int flags)
540{
Ram Paib58fed82005-11-07 17:16:09 -0500541 struct super_block *sb = mnt->mnt_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 int retval;
Ram Pai70fbcdf2005-11-07 17:17:04 -0500543 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544
545 retval = security_sb_umount(mnt, flags);
546 if (retval)
547 return retval;
548
549 /*
550 * Allow userspace to request a mountpoint be expired rather than
551 * unmounting unconditionally. Unmount only happens if:
552 * (1) the mark is already set (the mark is cleared by mntput())
553 * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
554 */
555 if (flags & MNT_EXPIRE) {
556 if (mnt == current->fs->rootmnt ||
557 flags & (MNT_FORCE | MNT_DETACH))
558 return -EINVAL;
559
560 if (atomic_read(&mnt->mnt_count) != 2)
561 return -EBUSY;
562
563 if (!xchg(&mnt->mnt_expiry_mark, 1))
564 return -EAGAIN;
565 }
566
567 /*
568 * If we may have to abort operations to get out of this
569 * mount, and they will themselves hold resources we must
570 * allow the fs to do things. In the Unix tradition of
571 * 'Gee thats tricky lets do it in userspace' the umount_begin
572 * might fail to complete on the first run through as other tasks
573 * must return, and the like. Thats for the mount program to worry
574 * about for the moment.
575 */
576
577 lock_kernel();
Trond Myklebust8b512d92006-06-09 09:34:18 -0400578 if (sb->s_op->umount_begin)
579 sb->s_op->umount_begin(mnt, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 unlock_kernel();
581
582 /*
583 * No sense to grab the lock for this test, but test itself looks
584 * somewhat bogus. Suggestions for better replacement?
585 * Ho-hum... In principle, we might treat that as umount + switch
586 * to rootfs. GC would eventually take care of the old vfsmount.
587 * Actually it makes sense, especially if rootfs would contain a
588 * /reboot - static binary that would close all descriptors and
589 * call reboot(9). Then init(8) could umount root and exec /reboot.
590 */
591 if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) {
592 /*
593 * Special case for "unmounting" root ...
594 * we just try to remount it readonly.
595 */
596 down_write(&sb->s_umount);
597 if (!(sb->s_flags & MS_RDONLY)) {
598 lock_kernel();
599 DQUOT_OFF(sb);
600 retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
601 unlock_kernel();
602 }
603 up_write(&sb->s_umount);
604 return retval;
605 }
606
Ram Pai390c6842005-11-07 17:17:51 -0500607 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 spin_lock(&vfsmount_lock);
Al Viro5addc5d2005-11-07 17:15:49 -0500609 event++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 retval = -EBUSY;
Ram Paia05964f2005-11-07 17:20:17 -0500612 if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613 if (!list_empty(&mnt->mnt_list))
Ram Paia05964f2005-11-07 17:20:17 -0500614 umount_tree(mnt, 1, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 retval = 0;
616 }
617 spin_unlock(&vfsmount_lock);
618 if (retval)
619 security_sb_umount_busy(mnt);
Ram Pai390c6842005-11-07 17:17:51 -0500620 up_write(&namespace_sem);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500621 release_mounts(&umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 return retval;
623}
624
625/*
626 * Now umount can handle mount points as well as block devices.
627 * This is important for filesystems which use unnamed block devices.
628 *
629 * We now support a flag for forced unmount like the other 'big iron'
630 * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
631 */
632
633asmlinkage long sys_umount(char __user * name, int flags)
634{
635 struct nameidata nd;
636 int retval;
637
638 retval = __user_walk(name, LOOKUP_FOLLOW, &nd);
639 if (retval)
640 goto out;
641 retval = -EINVAL;
642 if (nd.dentry != nd.mnt->mnt_root)
643 goto dput_and_out;
644 if (!check_mnt(nd.mnt))
645 goto dput_and_out;
646
647 retval = -EPERM;
648 if (!capable(CAP_SYS_ADMIN))
649 goto dput_and_out;
650
651 retval = do_umount(nd.mnt, flags);
652dput_and_out:
653 path_release_on_umount(&nd);
654out:
655 return retval;
656}
657
658#ifdef __ARCH_WANT_SYS_OLDUMOUNT
659
660/*
Ram Paib58fed82005-11-07 17:16:09 -0500661 * The 2.0 compatible umount. No flags.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663asmlinkage long sys_oldumount(char __user * name)
664{
Ram Paib58fed82005-11-07 17:16:09 -0500665 return sys_umount(name, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666}
667
668#endif
669
670static int mount_is_safe(struct nameidata *nd)
671{
672 if (capable(CAP_SYS_ADMIN))
673 return 0;
674 return -EPERM;
675#ifdef notyet
676 if (S_ISLNK(nd->dentry->d_inode->i_mode))
677 return -EPERM;
678 if (nd->dentry->d_inode->i_mode & S_ISVTX) {
679 if (current->uid != nd->dentry->d_inode->i_uid)
680 return -EPERM;
681 }
Christoph Hellwige4543ed2005-11-08 21:35:04 -0800682 if (vfs_permission(nd, MAY_WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 return -EPERM;
684 return 0;
685#endif
686}
687
Ram Paib58fed82005-11-07 17:16:09 -0500688static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689{
690 while (1) {
691 if (d == dentry)
692 return 1;
693 if (d == NULL || d == d->d_parent)
694 return 0;
695 d = d->d_parent;
696 }
697}
698
Ram Paib90fa9a2005-11-07 17:19:50 -0500699struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
Ram Pai36341f62005-11-07 17:17:22 -0500700 int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701{
702 struct vfsmount *res, *p, *q, *r, *s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 struct nameidata nd;
704
Ram Pai9676f0c2005-11-07 17:21:20 -0500705 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
706 return NULL;
707
Ram Pai36341f62005-11-07 17:17:22 -0500708 res = q = clone_mnt(mnt, dentry, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709 if (!q)
710 goto Enomem;
711 q->mnt_mountpoint = mnt->mnt_mountpoint;
712
713 p = mnt;
Domen Puncerfdadd652005-09-10 00:27:07 -0700714 list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry))
716 continue;
717
718 for (s = r; s; s = next_mnt(s, r)) {
Ram Pai9676f0c2005-11-07 17:21:20 -0500719 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) {
720 s = skip_mnt_tree(s);
721 continue;
722 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 while (p != s->mnt_parent) {
724 p = p->mnt_parent;
725 q = q->mnt_parent;
726 }
727 p = s;
728 nd.mnt = q;
729 nd.dentry = p->mnt_mountpoint;
Ram Pai36341f62005-11-07 17:17:22 -0500730 q = clone_mnt(p, p->mnt_root, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 if (!q)
732 goto Enomem;
733 spin_lock(&vfsmount_lock);
734 list_add_tail(&q->mnt_list, &res->mnt_list);
735 attach_mnt(q, &nd);
736 spin_unlock(&vfsmount_lock);
737 }
738 }
739 return res;
Ram Paib58fed82005-11-07 17:16:09 -0500740Enomem:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 if (res) {
Ram Pai70fbcdf2005-11-07 17:17:04 -0500742 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -0500744 umount_tree(res, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500746 release_mounts(&umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 }
748 return NULL;
749}
750
Ram Paib90fa9a2005-11-07 17:19:50 -0500751/*
752 * @source_mnt : mount tree to be attached
Ram Pai21444402005-11-07 17:20:03 -0500753 * @nd : place the mount tree @source_mnt is attached
754 * @parent_nd : if non-null, detach the source_mnt from its parent and
755 * store the parent mount and mountpoint dentry.
756 * (done when source_mnt is moved)
Ram Paib90fa9a2005-11-07 17:19:50 -0500757 *
758 * NOTE: in the table below explains the semantics when a source mount
759 * of a given type is attached to a destination mount of a given type.
Ram Pai9676f0c2005-11-07 17:21:20 -0500760 * ---------------------------------------------------------------------------
761 * | BIND MOUNT OPERATION |
762 * |**************************************************************************
763 * | source-->| shared | private | slave | unbindable |
764 * | dest | | | | |
765 * | | | | | | |
766 * | v | | | | |
767 * |**************************************************************************
768 * | shared | shared (++) | shared (+) | shared(+++)| invalid |
769 * | | | | | |
770 * |non-shared| shared (+) | private | slave (*) | invalid |
771 * ***************************************************************************
Ram Paib90fa9a2005-11-07 17:19:50 -0500772 * A bind operation clones the source mount and mounts the clone on the
773 * destination mount.
774 *
775 * (++) the cloned mount is propagated to all the mounts in the propagation
776 * tree of the destination mount and the cloned mount is added to
777 * the peer group of the source mount.
778 * (+) the cloned mount is created under the destination mount and is marked
779 * as shared. The cloned mount is added to the peer group of the source
780 * mount.
Ram Pai5afe0022005-11-07 17:21:01 -0500781 * (+++) the mount is propagated to all the mounts in the propagation tree
782 * of the destination mount and the cloned mount is made slave
783 * of the same master as that of the source mount. The cloned mount
784 * is marked as 'shared and slave'.
785 * (*) the cloned mount is made a slave of the same master as that of the
786 * source mount.
787 *
Ram Pai9676f0c2005-11-07 17:21:20 -0500788 * ---------------------------------------------------------------------------
789 * | MOVE MOUNT OPERATION |
790 * |**************************************************************************
791 * | source-->| shared | private | slave | unbindable |
792 * | dest | | | | |
793 * | | | | | | |
794 * | v | | | | |
795 * |**************************************************************************
796 * | shared | shared (+) | shared (+) | shared(+++) | invalid |
797 * | | | | | |
798 * |non-shared| shared (+*) | private | slave (*) | unbindable |
799 * ***************************************************************************
Ram Pai5afe0022005-11-07 17:21:01 -0500800 *
801 * (+) the mount is moved to the destination. And is then propagated to
802 * all the mounts in the propagation tree of the destination mount.
Ram Pai21444402005-11-07 17:20:03 -0500803 * (+*) the mount is moved to the destination.
Ram Pai5afe0022005-11-07 17:21:01 -0500804 * (+++) the mount is moved to the destination and is then propagated to
805 * all the mounts belonging to the destination mount's propagation tree.
806 * the mount is marked as 'shared and slave'.
807 * (*) the mount continues to be a slave at the new location.
Ram Paib90fa9a2005-11-07 17:19:50 -0500808 *
809 * if the source mount is a tree, the operations explained above is
810 * applied to each mount in the tree.
811 * Must be called without spinlocks held, since this function can sleep
812 * in allocations.
813 */
814static int attach_recursive_mnt(struct vfsmount *source_mnt,
Ram Pai21444402005-11-07 17:20:03 -0500815 struct nameidata *nd, struct nameidata *parent_nd)
Ram Paib90fa9a2005-11-07 17:19:50 -0500816{
817 LIST_HEAD(tree_list);
818 struct vfsmount *dest_mnt = nd->mnt;
819 struct dentry *dest_dentry = nd->dentry;
820 struct vfsmount *child, *p;
821
822 if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list))
823 return -EINVAL;
824
825 if (IS_MNT_SHARED(dest_mnt)) {
826 for (p = source_mnt; p; p = next_mnt(p, source_mnt))
827 set_mnt_shared(p);
828 }
829
830 spin_lock(&vfsmount_lock);
Ram Pai21444402005-11-07 17:20:03 -0500831 if (parent_nd) {
832 detach_mnt(source_mnt, parent_nd);
833 attach_mnt(source_mnt, nd);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800834 touch_mnt_namespace(current->nsproxy->mnt_ns);
Ram Pai21444402005-11-07 17:20:03 -0500835 } else {
836 mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
837 commit_tree(source_mnt);
838 }
Ram Paib90fa9a2005-11-07 17:19:50 -0500839
840 list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
841 list_del_init(&child->mnt_hash);
842 commit_tree(child);
843 }
844 spin_unlock(&vfsmount_lock);
845 return 0;
846}
847
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
849{
850 int err;
851 if (mnt->mnt_sb->s_flags & MS_NOUSER)
852 return -EINVAL;
853
854 if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
855 S_ISDIR(mnt->mnt_root->d_inode->i_mode))
856 return -ENOTDIR;
857
858 err = -ENOENT;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800859 mutex_lock(&nd->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860 if (IS_DEADDIR(nd->dentry->d_inode))
861 goto out_unlock;
862
863 err = security_sb_check_sb(mnt, nd);
864 if (err)
865 goto out_unlock;
866
867 err = -ENOENT;
Ram Paib90fa9a2005-11-07 17:19:50 -0500868 if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry))
Ram Pai21444402005-11-07 17:20:03 -0500869 err = attach_recursive_mnt(mnt, nd, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870out_unlock:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800871 mutex_unlock(&nd->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 if (!err)
873 security_sb_post_addmount(mnt, nd);
874 return err;
875}
876
877/*
Ram Pai07b20882005-11-07 17:19:07 -0500878 * recursively change the type of the mountpoint.
879 */
880static int do_change_type(struct nameidata *nd, int flag)
881{
882 struct vfsmount *m, *mnt = nd->mnt;
883 int recurse = flag & MS_REC;
884 int type = flag & ~MS_REC;
885
886 if (nd->dentry != nd->mnt->mnt_root)
887 return -EINVAL;
888
889 down_write(&namespace_sem);
890 spin_lock(&vfsmount_lock);
891 for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
892 change_mnt_propagation(m, type);
893 spin_unlock(&vfsmount_lock);
894 up_write(&namespace_sem);
895 return 0;
896}
897
898/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 * do loopback mount.
900 */
Andrew Mortoneee391a2006-05-15 09:44:30 -0700901static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902{
903 struct nameidata old_nd;
904 struct vfsmount *mnt = NULL;
905 int err = mount_is_safe(nd);
906 if (err)
907 return err;
908 if (!old_name || !*old_name)
909 return -EINVAL;
910 err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
911 if (err)
912 return err;
913
Ram Pai390c6842005-11-07 17:17:51 -0500914 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 err = -EINVAL;
Ram Pai9676f0c2005-11-07 17:21:20 -0500916 if (IS_MNT_UNBINDABLE(old_nd.mnt))
917 goto out;
918
Al Viroccd48bc2005-11-07 17:15:04 -0500919 if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
920 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921
Al Viroccd48bc2005-11-07 17:15:04 -0500922 err = -ENOMEM;
923 if (recurse)
Ram Pai36341f62005-11-07 17:17:22 -0500924 mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0);
Al Viroccd48bc2005-11-07 17:15:04 -0500925 else
Ram Pai36341f62005-11-07 17:17:22 -0500926 mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0);
Al Viroccd48bc2005-11-07 17:15:04 -0500927
928 if (!mnt)
929 goto out;
930
Al Viroccd48bc2005-11-07 17:15:04 -0500931 err = graft_tree(mnt, nd);
932 if (err) {
Ram Pai70fbcdf2005-11-07 17:17:04 -0500933 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -0500935 umount_tree(mnt, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500937 release_mounts(&umount_list);
Ram Pai5b83d2c2005-11-07 17:16:29 -0500938 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939
Al Viroccd48bc2005-11-07 17:15:04 -0500940out:
Ram Pai390c6842005-11-07 17:17:51 -0500941 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 path_release(&old_nd);
943 return err;
944}
945
946/*
947 * change filesystem flags. dir should be a physical root of filesystem.
948 * If you've mounted a non-root directory somewhere and want to do remount
949 * on it - tough luck.
950 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951static int do_remount(struct nameidata *nd, int flags, int mnt_flags,
952 void *data)
953{
954 int err;
Ram Paib58fed82005-11-07 17:16:09 -0500955 struct super_block *sb = nd->mnt->mnt_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956
957 if (!capable(CAP_SYS_ADMIN))
958 return -EPERM;
959
960 if (!check_mnt(nd->mnt))
961 return -EINVAL;
962
963 if (nd->dentry != nd->mnt->mnt_root)
964 return -EINVAL;
965
966 down_write(&sb->s_umount);
967 err = do_remount_sb(sb, flags, data, 0);
968 if (!err)
Ram Paib58fed82005-11-07 17:16:09 -0500969 nd->mnt->mnt_flags = mnt_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 up_write(&sb->s_umount);
971 if (!err)
972 security_sb_post_remount(nd->mnt, flags, data);
973 return err;
974}
975
Ram Pai9676f0c2005-11-07 17:21:20 -0500976static inline int tree_contains_unbindable(struct vfsmount *mnt)
977{
978 struct vfsmount *p;
979 for (p = mnt; p; p = next_mnt(p, mnt)) {
980 if (IS_MNT_UNBINDABLE(p))
981 return 1;
982 }
983 return 0;
984}
985
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986static int do_move_mount(struct nameidata *nd, char *old_name)
987{
988 struct nameidata old_nd, parent_nd;
989 struct vfsmount *p;
990 int err = 0;
991 if (!capable(CAP_SYS_ADMIN))
992 return -EPERM;
993 if (!old_name || !*old_name)
994 return -EINVAL;
995 err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
996 if (err)
997 return err;
998
Ram Pai390c6842005-11-07 17:17:51 -0500999 down_write(&namespace_sem);
Ram Paib58fed82005-11-07 17:16:09 -05001000 while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 ;
1002 err = -EINVAL;
1003 if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
1004 goto out;
1005
1006 err = -ENOENT;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001007 mutex_lock(&nd->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008 if (IS_DEADDIR(nd->dentry->d_inode))
1009 goto out1;
1010
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011 if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry))
Ram Pai21444402005-11-07 17:20:03 -05001012 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013
1014 err = -EINVAL;
1015 if (old_nd.dentry != old_nd.mnt->mnt_root)
Ram Pai21444402005-11-07 17:20:03 -05001016 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017
1018 if (old_nd.mnt == old_nd.mnt->mnt_parent)
Ram Pai21444402005-11-07 17:20:03 -05001019 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020
1021 if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
1022 S_ISDIR(old_nd.dentry->d_inode->i_mode))
Ram Pai21444402005-11-07 17:20:03 -05001023 goto out1;
1024 /*
1025 * Don't move a mount residing in a shared parent.
1026 */
1027 if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent))
1028 goto out1;
Ram Pai9676f0c2005-11-07 17:21:20 -05001029 /*
1030 * Don't move a mount tree containing unbindable mounts to a destination
1031 * mount which is shared.
1032 */
1033 if (IS_MNT_SHARED(nd->mnt) && tree_contains_unbindable(old_nd.mnt))
1034 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 err = -ELOOP;
Ram Paib58fed82005-11-07 17:16:09 -05001036 for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037 if (p == old_nd.mnt)
Ram Pai21444402005-11-07 17:20:03 -05001038 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039
Ram Pai21444402005-11-07 17:20:03 -05001040 if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd)))
1041 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042
Ram Pai21444402005-11-07 17:20:03 -05001043 spin_lock(&vfsmount_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 /* if the mount is moved, it should no longer be expire
1045 * automatically */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001046 list_del_init(&old_nd.mnt->mnt_expire);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047 spin_unlock(&vfsmount_lock);
1048out1:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001049 mutex_unlock(&nd->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050out:
Ram Pai390c6842005-11-07 17:17:51 -05001051 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052 if (!err)
1053 path_release(&parent_nd);
1054 path_release(&old_nd);
1055 return err;
1056}
1057
1058/*
1059 * create a new mount for userspace and request it to be added into the
1060 * namespace's tree
1061 */
1062static int do_new_mount(struct nameidata *nd, char *type, int flags,
1063 int mnt_flags, char *name, void *data)
1064{
1065 struct vfsmount *mnt;
1066
1067 if (!type || !memchr(type, 0, PAGE_SIZE))
1068 return -EINVAL;
1069
1070 /* we need capabilities... */
1071 if (!capable(CAP_SYS_ADMIN))
1072 return -EPERM;
1073
1074 mnt = do_kern_mount(type, flags, name, data);
1075 if (IS_ERR(mnt))
1076 return PTR_ERR(mnt);
1077
1078 return do_add_mount(mnt, nd, mnt_flags, NULL);
1079}
1080
1081/*
1082 * add a mount into a namespace's mount tree
1083 * - provide the option of adding the new mount to an expiration list
1084 */
1085int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
1086 int mnt_flags, struct list_head *fslist)
1087{
1088 int err;
1089
Ram Pai390c6842005-11-07 17:17:51 -05001090 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091 /* Something was mounted here while we slept */
Ram Paib58fed82005-11-07 17:16:09 -05001092 while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001093 ;
1094 err = -EINVAL;
1095 if (!check_mnt(nd->mnt))
1096 goto unlock;
1097
1098 /* Refuse the same filesystem on the same mount point */
1099 err = -EBUSY;
1100 if (nd->mnt->mnt_sb == newmnt->mnt_sb &&
1101 nd->mnt->mnt_root == nd->dentry)
1102 goto unlock;
1103
1104 err = -EINVAL;
1105 if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
1106 goto unlock;
1107
1108 newmnt->mnt_flags = mnt_flags;
Ram Pai5b83d2c2005-11-07 17:16:29 -05001109 if ((err = graft_tree(newmnt, nd)))
1110 goto unlock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111
Ram Pai5b83d2c2005-11-07 17:16:29 -05001112 if (fslist) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 /* add to the specified expiration list */
1114 spin_lock(&vfsmount_lock);
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001115 list_add_tail(&newmnt->mnt_expire, fslist);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116 spin_unlock(&vfsmount_lock);
1117 }
Ram Pai390c6842005-11-07 17:17:51 -05001118 up_write(&namespace_sem);
Ram Pai5b83d2c2005-11-07 17:16:29 -05001119 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120
1121unlock:
Ram Pai390c6842005-11-07 17:17:51 -05001122 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123 mntput(newmnt);
1124 return err;
1125}
1126
1127EXPORT_SYMBOL_GPL(do_add_mount);
1128
Ram Pai70fbcdf2005-11-07 17:17:04 -05001129static void expire_mount(struct vfsmount *mnt, struct list_head *mounts,
1130 struct list_head *umounts)
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001131{
1132 spin_lock(&vfsmount_lock);
1133
1134 /*
Miklos Szeredied42c872005-07-07 17:57:26 -07001135 * Check if mount is still attached, if not, let whoever holds it deal
1136 * with the sucker
1137 */
1138 if (mnt->mnt_parent == mnt) {
1139 spin_unlock(&vfsmount_lock);
1140 return;
1141 }
1142
1143 /*
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001144 * Check that it is still dead: the count should now be 2 - as
1145 * contributed by the vfsmount parent and the mntget above
1146 */
Ram Paia05964f2005-11-07 17:20:17 -05001147 if (!propagate_mount_busy(mnt, 2)) {
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001148 /* delete from the namespace */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001149 touch_mnt_namespace(mnt->mnt_ns);
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001150 list_del_init(&mnt->mnt_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001151 mnt->mnt_ns = NULL;
Ram Paia05964f2005-11-07 17:20:17 -05001152 umount_tree(mnt, 1, umounts);
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001153 spin_unlock(&vfsmount_lock);
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001154 } else {
1155 /*
1156 * Someone brought it back to life whilst we didn't have any
1157 * locks held so return it to the expiration list
1158 */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001159 list_add_tail(&mnt->mnt_expire, mounts);
Miklos Szeredi24ca2af2005-07-07 17:57:25 -07001160 spin_unlock(&vfsmount_lock);
1161 }
1162}
1163
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164/*
Trond Myklebust5528f9112006-06-09 09:34:17 -04001165 * go through the vfsmounts we've just consigned to the graveyard to
1166 * - check that they're still dead
1167 * - delete the vfsmount from the appropriate namespace under lock
1168 * - dispose of the corpse
1169 */
1170static void expire_mount_list(struct list_head *graveyard, struct list_head *mounts)
1171{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001172 struct mnt_namespace *ns;
Trond Myklebust5528f9112006-06-09 09:34:17 -04001173 struct vfsmount *mnt;
1174
1175 while (!list_empty(graveyard)) {
1176 LIST_HEAD(umounts);
1177 mnt = list_entry(graveyard->next, struct vfsmount, mnt_expire);
1178 list_del_init(&mnt->mnt_expire);
1179
1180 /* don't do anything if the namespace is dead - all the
1181 * vfsmounts from it are going away anyway */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001182 ns = mnt->mnt_ns;
1183 if (!ns || !ns->root)
Trond Myklebust5528f9112006-06-09 09:34:17 -04001184 continue;
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001185 get_mnt_ns(ns);
Trond Myklebust5528f9112006-06-09 09:34:17 -04001186
1187 spin_unlock(&vfsmount_lock);
1188 down_write(&namespace_sem);
1189 expire_mount(mnt, mounts, &umounts);
1190 up_write(&namespace_sem);
1191 release_mounts(&umounts);
1192 mntput(mnt);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001193 put_mnt_ns(ns);
Trond Myklebust5528f9112006-06-09 09:34:17 -04001194 spin_lock(&vfsmount_lock);
1195 }
1196}
1197
1198/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199 * process a list of expirable mountpoints with the intent of discarding any
1200 * mountpoints that aren't in use and haven't been touched since last we came
1201 * here
1202 */
1203void mark_mounts_for_expiry(struct list_head *mounts)
1204{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 struct vfsmount *mnt, *next;
1206 LIST_HEAD(graveyard);
1207
1208 if (list_empty(mounts))
1209 return;
1210
1211 spin_lock(&vfsmount_lock);
1212
1213 /* extract from the expiration list every vfsmount that matches the
1214 * following criteria:
1215 * - only referenced by its parent vfsmount
1216 * - still marked for expiry (marked on the last call here; marks are
1217 * cleared by mntput())
1218 */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001219 list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 if (!xchg(&mnt->mnt_expiry_mark, 1) ||
1221 atomic_read(&mnt->mnt_count) != 1)
1222 continue;
1223
1224 mntget(mnt);
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001225 list_move(&mnt->mnt_expire, &graveyard);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226 }
1227
Trond Myklebust5528f9112006-06-09 09:34:17 -04001228 expire_mount_list(&graveyard, mounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229
1230 spin_unlock(&vfsmount_lock);
1231}
1232
1233EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
1234
1235/*
Trond Myklebust5528f9112006-06-09 09:34:17 -04001236 * Ripoff of 'select_parent()'
1237 *
1238 * search the list of submounts for a given mountpoint, and move any
1239 * shrinkable submounts to the 'graveyard' list.
1240 */
1241static int select_submounts(struct vfsmount *parent, struct list_head *graveyard)
1242{
1243 struct vfsmount *this_parent = parent;
1244 struct list_head *next;
1245 int found = 0;
1246
1247repeat:
1248 next = this_parent->mnt_mounts.next;
1249resume:
1250 while (next != &this_parent->mnt_mounts) {
1251 struct list_head *tmp = next;
1252 struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child);
1253
1254 next = tmp->next;
1255 if (!(mnt->mnt_flags & MNT_SHRINKABLE))
1256 continue;
1257 /*
1258 * Descend a level if the d_mounts list is non-empty.
1259 */
1260 if (!list_empty(&mnt->mnt_mounts)) {
1261 this_parent = mnt;
1262 goto repeat;
1263 }
1264
1265 if (!propagate_mount_busy(mnt, 1)) {
1266 mntget(mnt);
1267 list_move_tail(&mnt->mnt_expire, graveyard);
1268 found++;
1269 }
1270 }
1271 /*
1272 * All done at this level ... ascend and resume the search
1273 */
1274 if (this_parent != parent) {
1275 next = this_parent->mnt_child.next;
1276 this_parent = this_parent->mnt_parent;
1277 goto resume;
1278 }
1279 return found;
1280}
1281
1282/*
1283 * process a list of expirable mountpoints with the intent of discarding any
1284 * submounts of a specific parent mountpoint
1285 */
1286void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts)
1287{
1288 LIST_HEAD(graveyard);
1289 int found;
1290
1291 spin_lock(&vfsmount_lock);
1292
1293 /* extract submounts of 'mountpoint' from the expiration list */
1294 while ((found = select_submounts(mountpoint, &graveyard)) != 0)
1295 expire_mount_list(&graveyard, mounts);
1296
1297 spin_unlock(&vfsmount_lock);
1298}
1299
1300EXPORT_SYMBOL_GPL(shrink_submounts);
1301
1302/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303 * Some copy_from_user() implementations do not return the exact number of
1304 * bytes remaining to copy on a fault. But copy_mount_options() requires that.
1305 * Note that this function differs from copy_from_user() in that it will oops
1306 * on bad values of `to', rather than returning a short copy.
1307 */
Ram Paib58fed82005-11-07 17:16:09 -05001308static long exact_copy_from_user(void *to, const void __user * from,
1309 unsigned long n)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310{
1311 char *t = to;
1312 const char __user *f = from;
1313 char c;
1314
1315 if (!access_ok(VERIFY_READ, from, n))
1316 return n;
1317
1318 while (n) {
1319 if (__get_user(c, f)) {
1320 memset(t, 0, n);
1321 break;
1322 }
1323 *t++ = c;
1324 f++;
1325 n--;
1326 }
1327 return n;
1328}
1329
Ram Paib58fed82005-11-07 17:16:09 -05001330int copy_mount_options(const void __user * data, unsigned long *where)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331{
1332 int i;
1333 unsigned long page;
1334 unsigned long size;
Ram Paib58fed82005-11-07 17:16:09 -05001335
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336 *where = 0;
1337 if (!data)
1338 return 0;
1339
1340 if (!(page = __get_free_page(GFP_KERNEL)))
1341 return -ENOMEM;
1342
1343 /* We only care that *some* data at the address the user
1344 * gave us is valid. Just in case, we'll zero
1345 * the remainder of the page.
1346 */
1347 /* copy_from_user cannot cross TASK_SIZE ! */
1348 size = TASK_SIZE - (unsigned long)data;
1349 if (size > PAGE_SIZE)
1350 size = PAGE_SIZE;
1351
1352 i = size - exact_copy_from_user((void *)page, data, size);
1353 if (!i) {
Ram Paib58fed82005-11-07 17:16:09 -05001354 free_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 return -EFAULT;
1356 }
1357 if (i != PAGE_SIZE)
1358 memset((char *)page + i, 0, PAGE_SIZE - i);
1359 *where = page;
1360 return 0;
1361}
1362
1363/*
1364 * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
1365 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
1366 *
1367 * data is a (void *) that can point to any structure up to
1368 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
1369 * information (or be NULL).
1370 *
1371 * Pre-0.97 versions of mount() didn't have a flags word.
1372 * When the flags word was introduced its top half was required
1373 * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
1374 * Therefore, if this magic number is present, it carries no information
1375 * and must be discarded.
1376 */
Ram Paib58fed82005-11-07 17:16:09 -05001377long do_mount(char *dev_name, char *dir_name, char *type_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378 unsigned long flags, void *data_page)
1379{
1380 struct nameidata nd;
1381 int retval = 0;
1382 int mnt_flags = 0;
1383
1384 /* Discard magic */
1385 if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
1386 flags &= ~MS_MGC_MSK;
1387
1388 /* Basic sanity checks */
1389
1390 if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
1391 return -EINVAL;
1392 if (dev_name && !memchr(dev_name, 0, PAGE_SIZE))
1393 return -EINVAL;
1394
1395 if (data_page)
1396 ((char *)data_page)[PAGE_SIZE - 1] = 0;
1397
1398 /* Separate the per-mountpoint flags */
1399 if (flags & MS_NOSUID)
1400 mnt_flags |= MNT_NOSUID;
1401 if (flags & MS_NODEV)
1402 mnt_flags |= MNT_NODEV;
1403 if (flags & MS_NOEXEC)
1404 mnt_flags |= MNT_NOEXEC;
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -08001405 if (flags & MS_NOATIME)
1406 mnt_flags |= MNT_NOATIME;
1407 if (flags & MS_NODIRATIME)
1408 mnt_flags |= MNT_NODIRATIME;
Valerie Henson47ae32d2006-12-13 00:34:34 -08001409 if (flags & MS_RELATIME)
1410 mnt_flags |= MNT_RELATIME;
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -08001411
1412 flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
Valerie Henson47ae32d2006-12-13 00:34:34 -08001413 MS_NOATIME | MS_NODIRATIME | MS_RELATIME);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414
1415 /* ... and get the mountpoint */
1416 retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
1417 if (retval)
1418 return retval;
1419
1420 retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page);
1421 if (retval)
1422 goto dput_out;
1423
1424 if (flags & MS_REMOUNT)
1425 retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags,
1426 data_page);
1427 else if (flags & MS_BIND)
Andrew Mortoneee391a2006-05-15 09:44:30 -07001428 retval = do_loopback(&nd, dev_name, flags & MS_REC);
Ram Pai9676f0c2005-11-07 17:21:20 -05001429 else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
Ram Pai07b20882005-11-07 17:19:07 -05001430 retval = do_change_type(&nd, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431 else if (flags & MS_MOVE)
1432 retval = do_move_mount(&nd, dev_name);
1433 else
1434 retval = do_new_mount(&nd, type_page, flags, mnt_flags,
1435 dev_name, data_page);
1436dput_out:
1437 path_release(&nd);
1438 return retval;
1439}
1440
JANAK DESAI741a2952006-02-07 12:59:00 -08001441/*
1442 * Allocate a new namespace structure and populate it with contents
1443 * copied from the namespace of the passed in task structure.
1444 */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001445struct mnt_namespace *dup_mnt_ns(struct task_struct *tsk,
1446 struct fs_struct *fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001448 struct mnt_namespace *mnt_ns = tsk->nsproxy->mnt_ns;
1449 struct mnt_namespace *new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451 struct vfsmount *p, *q;
1452
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001453 new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001454 if (!new_ns)
Adrian Bunkf13b8352006-03-15 17:37:32 +01001455 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001456
1457 atomic_set(&new_ns->count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 INIT_LIST_HEAD(&new_ns->list);
Al Viro5addc5d2005-11-07 17:15:49 -05001459 init_waitqueue_head(&new_ns->poll);
1460 new_ns->event = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461
Ram Pai390c6842005-11-07 17:17:51 -05001462 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463 /* First pass: copy the tree topology */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001464 new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root,
Ram Pai9676f0c2005-11-07 17:21:20 -05001465 CL_COPY_ALL | CL_EXPIRE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 if (!new_ns->root) {
Ram Pai390c6842005-11-07 17:17:51 -05001467 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468 kfree(new_ns);
Adrian Bunkf13b8352006-03-15 17:37:32 +01001469 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 }
1471 spin_lock(&vfsmount_lock);
1472 list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
1473 spin_unlock(&vfsmount_lock);
1474
1475 /*
1476 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
1477 * as belonging to new namespace. We have already acquired a private
1478 * fs_struct, so tsk->fs->lock is not needed.
1479 */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001480 p = mnt_ns->root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001481 q = new_ns->root;
1482 while (p) {
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001483 q->mnt_ns = new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484 if (fs) {
1485 if (p == fs->rootmnt) {
1486 rootmnt = p;
1487 fs->rootmnt = mntget(q);
1488 }
1489 if (p == fs->pwdmnt) {
1490 pwdmnt = p;
1491 fs->pwdmnt = mntget(q);
1492 }
1493 if (p == fs->altrootmnt) {
1494 altrootmnt = p;
1495 fs->altrootmnt = mntget(q);
1496 }
1497 }
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001498 p = next_mnt(p, mnt_ns->root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499 q = next_mnt(q, new_ns->root);
1500 }
Ram Pai390c6842005-11-07 17:17:51 -05001501 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503 if (rootmnt)
1504 mntput(rootmnt);
1505 if (pwdmnt)
1506 mntput(pwdmnt);
1507 if (altrootmnt)
1508 mntput(altrootmnt);
1509
JANAK DESAI741a2952006-02-07 12:59:00 -08001510 return new_ns;
1511}
1512
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001513int copy_mnt_ns(int flags, struct task_struct *tsk)
JANAK DESAI741a2952006-02-07 12:59:00 -08001514{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001515 struct mnt_namespace *ns = tsk->nsproxy->mnt_ns;
1516 struct mnt_namespace *new_ns;
JANAK DESAI741a2952006-02-07 12:59:00 -08001517 int err = 0;
1518
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001519 if (!ns)
JANAK DESAI741a2952006-02-07 12:59:00 -08001520 return 0;
1521
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001522 get_mnt_ns(ns);
JANAK DESAI741a2952006-02-07 12:59:00 -08001523
1524 if (!(flags & CLONE_NEWNS))
1525 return 0;
1526
1527 if (!capable(CAP_SYS_ADMIN)) {
1528 err = -EPERM;
1529 goto out;
1530 }
1531
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001532 new_ns = dup_mnt_ns(tsk, tsk->fs);
JANAK DESAI741a2952006-02-07 12:59:00 -08001533 if (!new_ns) {
1534 err = -ENOMEM;
1535 goto out;
1536 }
1537
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001538 tsk->nsproxy->mnt_ns = new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539
1540out:
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001541 put_mnt_ns(ns);
JANAK DESAI741a2952006-02-07 12:59:00 -08001542 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543}
1544
1545asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name,
1546 char __user * type, unsigned long flags,
1547 void __user * data)
1548{
1549 int retval;
1550 unsigned long data_page;
1551 unsigned long type_page;
1552 unsigned long dev_page;
1553 char *dir_page;
1554
Ram Paib58fed82005-11-07 17:16:09 -05001555 retval = copy_mount_options(type, &type_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 if (retval < 0)
1557 return retval;
1558
1559 dir_page = getname(dir_name);
1560 retval = PTR_ERR(dir_page);
1561 if (IS_ERR(dir_page))
1562 goto out1;
1563
Ram Paib58fed82005-11-07 17:16:09 -05001564 retval = copy_mount_options(dev_name, &dev_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565 if (retval < 0)
1566 goto out2;
1567
Ram Paib58fed82005-11-07 17:16:09 -05001568 retval = copy_mount_options(data, &data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001569 if (retval < 0)
1570 goto out3;
1571
1572 lock_kernel();
Ram Paib58fed82005-11-07 17:16:09 -05001573 retval = do_mount((char *)dev_page, dir_page, (char *)type_page,
1574 flags, (void *)data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575 unlock_kernel();
1576 free_page(data_page);
1577
1578out3:
1579 free_page(dev_page);
1580out2:
1581 putname(dir_page);
1582out1:
1583 free_page(type_page);
1584 return retval;
1585}
1586
1587/*
1588 * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
1589 * It can block. Requires the big lock held.
1590 */
1591void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt,
1592 struct dentry *dentry)
1593{
1594 struct dentry *old_root;
1595 struct vfsmount *old_rootmnt;
1596 write_lock(&fs->lock);
1597 old_root = fs->root;
1598 old_rootmnt = fs->rootmnt;
1599 fs->rootmnt = mntget(mnt);
1600 fs->root = dget(dentry);
1601 write_unlock(&fs->lock);
1602 if (old_root) {
1603 dput(old_root);
1604 mntput(old_rootmnt);
1605 }
1606}
1607
1608/*
1609 * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
1610 * It can block. Requires the big lock held.
1611 */
1612void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt,
1613 struct dentry *dentry)
1614{
1615 struct dentry *old_pwd;
1616 struct vfsmount *old_pwdmnt;
1617
1618 write_lock(&fs->lock);
1619 old_pwd = fs->pwd;
1620 old_pwdmnt = fs->pwdmnt;
1621 fs->pwdmnt = mntget(mnt);
1622 fs->pwd = dget(dentry);
1623 write_unlock(&fs->lock);
1624
1625 if (old_pwd) {
1626 dput(old_pwd);
1627 mntput(old_pwdmnt);
1628 }
1629}
1630
1631static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
1632{
1633 struct task_struct *g, *p;
1634 struct fs_struct *fs;
1635
1636 read_lock(&tasklist_lock);
1637 do_each_thread(g, p) {
1638 task_lock(p);
1639 fs = p->fs;
1640 if (fs) {
1641 atomic_inc(&fs->count);
1642 task_unlock(p);
Ram Paib58fed82005-11-07 17:16:09 -05001643 if (fs->root == old_nd->dentry
1644 && fs->rootmnt == old_nd->mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 set_fs_root(fs, new_nd->mnt, new_nd->dentry);
Ram Paib58fed82005-11-07 17:16:09 -05001646 if (fs->pwd == old_nd->dentry
1647 && fs->pwdmnt == old_nd->mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648 set_fs_pwd(fs, new_nd->mnt, new_nd->dentry);
1649 put_fs_struct(fs);
1650 } else
1651 task_unlock(p);
1652 } while_each_thread(g, p);
1653 read_unlock(&tasklist_lock);
1654}
1655
1656/*
1657 * pivot_root Semantics:
1658 * Moves the root file system of the current process to the directory put_old,
1659 * makes new_root as the new root file system of the current process, and sets
1660 * root/cwd of all processes which had them on the current root to new_root.
1661 *
1662 * Restrictions:
1663 * The new_root and put_old must be directories, and must not be on the
1664 * same file system as the current process root. The put_old must be
1665 * underneath new_root, i.e. adding a non-zero number of /.. to the string
1666 * pointed to by put_old must yield the same directory as new_root. No other
1667 * file system may be mounted on put_old. After all, new_root is a mountpoint.
1668 *
Neil Brown4a0d11f2006-01-08 01:03:18 -08001669 * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
1670 * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
1671 * in this situation.
1672 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 * Notes:
1674 * - we don't move root/cwd if they are not at the root (reason: if something
1675 * cared enough to change them, it's probably wrong to force them elsewhere)
1676 * - it's okay to pick a root that isn't the root of a file system, e.g.
1677 * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
1678 * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
1679 * first.
1680 */
Ram Paib58fed82005-11-07 17:16:09 -05001681asmlinkage long sys_pivot_root(const char __user * new_root,
1682 const char __user * put_old)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683{
1684 struct vfsmount *tmp;
1685 struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd;
1686 int error;
1687
1688 if (!capable(CAP_SYS_ADMIN))
1689 return -EPERM;
1690
1691 lock_kernel();
1692
Ram Paib58fed82005-11-07 17:16:09 -05001693 error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
1694 &new_nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 if (error)
1696 goto out0;
1697 error = -EINVAL;
1698 if (!check_mnt(new_nd.mnt))
1699 goto out1;
1700
Ram Paib58fed82005-11-07 17:16:09 -05001701 error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 if (error)
1703 goto out1;
1704
1705 error = security_sb_pivotroot(&old_nd, &new_nd);
1706 if (error) {
1707 path_release(&old_nd);
1708 goto out1;
1709 }
1710
1711 read_lock(&current->fs->lock);
1712 user_nd.mnt = mntget(current->fs->rootmnt);
1713 user_nd.dentry = dget(current->fs->root);
1714 read_unlock(&current->fs->lock);
Ram Pai390c6842005-11-07 17:17:51 -05001715 down_write(&namespace_sem);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001716 mutex_lock(&old_nd.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717 error = -EINVAL;
Ram Pai21444402005-11-07 17:20:03 -05001718 if (IS_MNT_SHARED(old_nd.mnt) ||
1719 IS_MNT_SHARED(new_nd.mnt->mnt_parent) ||
1720 IS_MNT_SHARED(user_nd.mnt->mnt_parent))
1721 goto out2;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722 if (!check_mnt(user_nd.mnt))
1723 goto out2;
1724 error = -ENOENT;
1725 if (IS_DEADDIR(new_nd.dentry->d_inode))
1726 goto out2;
1727 if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry))
1728 goto out2;
1729 if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry))
1730 goto out2;
1731 error = -EBUSY;
1732 if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt)
1733 goto out2; /* loop, on the same file system */
1734 error = -EINVAL;
1735 if (user_nd.mnt->mnt_root != user_nd.dentry)
1736 goto out2; /* not a mountpoint */
Miklos Szeredi0bb6fcc2005-09-06 15:19:36 -07001737 if (user_nd.mnt->mnt_parent == user_nd.mnt)
1738 goto out2; /* not attached */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739 if (new_nd.mnt->mnt_root != new_nd.dentry)
1740 goto out2; /* not a mountpoint */
Miklos Szeredi0bb6fcc2005-09-06 15:19:36 -07001741 if (new_nd.mnt->mnt_parent == new_nd.mnt)
1742 goto out2; /* not attached */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743 tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */
1744 spin_lock(&vfsmount_lock);
1745 if (tmp != new_nd.mnt) {
1746 for (;;) {
1747 if (tmp->mnt_parent == tmp)
1748 goto out3; /* already mounted on put_old */
1749 if (tmp->mnt_parent == new_nd.mnt)
1750 break;
1751 tmp = tmp->mnt_parent;
1752 }
1753 if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry))
1754 goto out3;
1755 } else if (!is_subdir(old_nd.dentry, new_nd.dentry))
1756 goto out3;
1757 detach_mnt(new_nd.mnt, &parent_nd);
1758 detach_mnt(user_nd.mnt, &root_parent);
1759 attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */
1760 attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001761 touch_mnt_namespace(current->nsproxy->mnt_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762 spin_unlock(&vfsmount_lock);
1763 chroot_fs_refs(&user_nd, &new_nd);
1764 security_sb_post_pivotroot(&user_nd, &new_nd);
1765 error = 0;
1766 path_release(&root_parent);
1767 path_release(&parent_nd);
1768out2:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001769 mutex_unlock(&old_nd.dentry->d_inode->i_mutex);
Ram Pai390c6842005-11-07 17:17:51 -05001770 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 path_release(&user_nd);
1772 path_release(&old_nd);
1773out1:
1774 path_release(&new_nd);
1775out0:
1776 unlock_kernel();
1777 return error;
1778out3:
1779 spin_unlock(&vfsmount_lock);
1780 goto out2;
1781}
1782
1783static void __init init_mount_tree(void)
1784{
1785 struct vfsmount *mnt;
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001786 struct mnt_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787
1788 mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
1789 if (IS_ERR(mnt))
1790 panic("Can't create rootfs");
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001791 ns = kmalloc(sizeof(*ns), GFP_KERNEL);
1792 if (!ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793 panic("Can't allocate initial namespace");
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001794 atomic_set(&ns->count, 1);
1795 INIT_LIST_HEAD(&ns->list);
1796 init_waitqueue_head(&ns->poll);
1797 ns->event = 0;
1798 list_add(&mnt->mnt_list, &ns->list);
1799 ns->root = mnt;
1800 mnt->mnt_ns = ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001802 init_task.nsproxy->mnt_ns = ns;
1803 get_mnt_ns(ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001805 set_fs_pwd(current->fs, ns->root, ns->root->mnt_root);
1806 set_fs_root(current->fs, ns->root, ns->root->mnt_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807}
1808
1809void __init mnt_init(unsigned long mempages)
1810{
1811 struct list_head *d;
1812 unsigned int nr_hash;
1813 int i;
Randy Dunlap15a67dd2006-09-29 01:58:57 -07001814 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815
Ram Pai390c6842005-11-07 17:17:51 -05001816 init_rwsem(&namespace_sem);
1817
Linus Torvalds1da177e2005-04-16 15:20:36 -07001818 mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
Ram Paib58fed82005-11-07 17:16:09 -05001819 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820
Ram Paib58fed82005-11-07 17:16:09 -05001821 mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001822
1823 if (!mount_hashtable)
1824 panic("Failed to allocate mount hash table\n");
1825
1826 /*
1827 * Find the power-of-two list-heads that can fit into the allocation..
1828 * We don't guarantee that "sizeof(struct list_head)" is necessarily
1829 * a power-of-two.
1830 */
1831 nr_hash = PAGE_SIZE / sizeof(struct list_head);
1832 hash_bits = 0;
1833 do {
1834 hash_bits++;
1835 } while ((nr_hash >> hash_bits) != 0);
1836 hash_bits--;
1837
1838 /*
1839 * Re-calculate the actual number of entries and the mask
1840 * from the number of bits we can fit.
1841 */
1842 nr_hash = 1UL << hash_bits;
Ram Paib58fed82005-11-07 17:16:09 -05001843 hash_mask = nr_hash - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844
1845 printk("Mount-cache hash table entries: %d\n", nr_hash);
1846
1847 /* And initialize the newly allocated array */
1848 d = mount_hashtable;
1849 i = nr_hash;
1850 do {
1851 INIT_LIST_HEAD(d);
1852 d++;
1853 i--;
1854 } while (i);
Randy Dunlap15a67dd2006-09-29 01:58:57 -07001855 err = sysfs_init();
1856 if (err)
1857 printk(KERN_WARNING "%s: sysfs_init error: %d\n",
1858 __FUNCTION__, err);
1859 err = subsystem_register(&fs_subsys);
1860 if (err)
1861 printk(KERN_WARNING "%s: subsystem_register error: %d\n",
1862 __FUNCTION__, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 init_rootfs();
1864 init_mount_tree();
1865}
1866
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001867void __put_mnt_ns(struct mnt_namespace *ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001869 struct vfsmount *root = ns->root;
Ram Pai70fbcdf2005-11-07 17:17:04 -05001870 LIST_HEAD(umount_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001871 ns->root = NULL;
Miklos Szeredi1ce88cf2005-07-07 17:57:24 -07001872 spin_unlock(&vfsmount_lock);
Ram Pai390c6842005-11-07 17:17:51 -05001873 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -05001875 umount_tree(root, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876 spin_unlock(&vfsmount_lock);
Ram Pai390c6842005-11-07 17:17:51 -05001877 up_write(&namespace_sem);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001878 release_mounts(&umount_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001879 kfree(ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880}