11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namespace.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * (C) Copyright Al Viro 2000, 2001 51da177e4SLinus Torvalds * Released under GPL v2. 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Based on code from fs/super.c, copyright Linus Torvalds and others. 81da177e4SLinus Torvalds * Heavily rewritten. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds #include <linux/config.h> 121da177e4SLinus Torvalds #include <linux/syscalls.h> 131da177e4SLinus Torvalds #include <linux/slab.h> 141da177e4SLinus Torvalds #include <linux/sched.h> 151da177e4SLinus Torvalds #include <linux/smp_lock.h> 161da177e4SLinus Torvalds #include <linux/init.h> 171da177e4SLinus Torvalds #include <linux/quotaops.h> 181da177e4SLinus Torvalds #include <linux/acct.h> 191da177e4SLinus Torvalds #include <linux/module.h> 201da177e4SLinus Torvalds #include <linux/seq_file.h> 211da177e4SLinus Torvalds #include <linux/namespace.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/security.h> 241da177e4SLinus Torvalds #include <linux/mount.h> 251da177e4SLinus Torvalds #include <asm/uaccess.h> 261da177e4SLinus Torvalds #include <asm/unistd.h> 271da177e4SLinus Torvalds 281da177e4SLinus Torvalds extern int __init init_rootfs(void); 291da177e4SLinus Torvalds 301da177e4SLinus Torvalds #ifdef CONFIG_SYSFS 311da177e4SLinus Torvalds extern int __init sysfs_init(void); 321da177e4SLinus Torvalds #else 331da177e4SLinus Torvalds static inline int sysfs_init(void) 341da177e4SLinus Torvalds { 351da177e4SLinus Torvalds return 0; 361da177e4SLinus Torvalds } 371da177e4SLinus Torvalds #endif 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds /* spinlock for vfsmount related operations, inplace of dcache_lock */ 401da177e4SLinus Torvalds __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); 411da177e4SLinus Torvalds 425addc5ddSAl Viro static int event; 435addc5ddSAl Viro 441da177e4SLinus Torvalds static struct list_head *mount_hashtable; 456c231b7bSRavikiran G Thirumalai static int hash_mask __read_mostly, hash_bits __read_mostly; 461da177e4SLinus Torvalds static kmem_cache_t *mnt_cache; 471da177e4SLinus Torvalds 481da177e4SLinus Torvalds static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) 491da177e4SLinus Torvalds { 501da177e4SLinus Torvalds unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); 511da177e4SLinus Torvalds tmp += ((unsigned long)dentry / L1_CACHE_BYTES); 521da177e4SLinus Torvalds tmp = tmp + (tmp >> hash_bits); 531da177e4SLinus Torvalds return tmp & hash_mask; 541da177e4SLinus Torvalds } 551da177e4SLinus Torvalds 561da177e4SLinus Torvalds struct vfsmount *alloc_vfsmnt(const char *name) 571da177e4SLinus Torvalds { 581da177e4SLinus Torvalds struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL); 591da177e4SLinus Torvalds if (mnt) { 601da177e4SLinus Torvalds memset(mnt, 0, sizeof(struct vfsmount)); 611da177e4SLinus Torvalds atomic_set(&mnt->mnt_count, 1); 621da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_hash); 631da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_child); 641da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_mounts); 651da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_list); 6655e700b9SMiklos Szeredi INIT_LIST_HEAD(&mnt->mnt_expire); 671da177e4SLinus Torvalds if (name) { 681da177e4SLinus Torvalds int size = strlen(name) + 1; 691da177e4SLinus Torvalds char *newname = kmalloc(size, GFP_KERNEL); 701da177e4SLinus Torvalds if (newname) { 711da177e4SLinus Torvalds memcpy(newname, name, size); 721da177e4SLinus Torvalds mnt->mnt_devname = newname; 731da177e4SLinus Torvalds } 741da177e4SLinus Torvalds } 751da177e4SLinus Torvalds } 761da177e4SLinus Torvalds return mnt; 771da177e4SLinus Torvalds } 781da177e4SLinus Torvalds 791da177e4SLinus Torvalds void free_vfsmnt(struct vfsmount *mnt) 801da177e4SLinus Torvalds { 811da177e4SLinus Torvalds kfree(mnt->mnt_devname); 821da177e4SLinus Torvalds kmem_cache_free(mnt_cache, mnt); 831da177e4SLinus Torvalds } 841da177e4SLinus Torvalds 851da177e4SLinus Torvalds /* 861da177e4SLinus Torvalds * Now, lookup_mnt increments the ref count before returning 871da177e4SLinus Torvalds * the vfsmount struct. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) 901da177e4SLinus Torvalds { 911da177e4SLinus Torvalds struct list_head *head = mount_hashtable + hash(mnt, dentry); 921da177e4SLinus Torvalds struct list_head *tmp = head; 931da177e4SLinus Torvalds struct vfsmount *p, *found = NULL; 941da177e4SLinus Torvalds 951da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 961da177e4SLinus Torvalds for (;;) { 971da177e4SLinus Torvalds tmp = tmp->next; 981da177e4SLinus Torvalds p = NULL; 991da177e4SLinus Torvalds if (tmp == head) 1001da177e4SLinus Torvalds break; 1011da177e4SLinus Torvalds p = list_entry(tmp, struct vfsmount, mnt_hash); 1021da177e4SLinus Torvalds if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { 1031da177e4SLinus Torvalds found = mntget(p); 1041da177e4SLinus Torvalds break; 1051da177e4SLinus Torvalds } 1061da177e4SLinus Torvalds } 1071da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1081da177e4SLinus Torvalds return found; 1091da177e4SLinus Torvalds } 1101da177e4SLinus Torvalds 1111da177e4SLinus Torvalds static inline int check_mnt(struct vfsmount *mnt) 1121da177e4SLinus Torvalds { 1131da177e4SLinus Torvalds return mnt->mnt_namespace == current->namespace; 1141da177e4SLinus Torvalds } 1151da177e4SLinus Torvalds 1165addc5ddSAl Viro static void touch_namespace(struct namespace *ns) 1175addc5ddSAl Viro { 1185addc5ddSAl Viro if (ns) { 1195addc5ddSAl Viro ns->event = ++event; 1205addc5ddSAl Viro wake_up_interruptible(&ns->poll); 1215addc5ddSAl Viro } 1225addc5ddSAl Viro } 1235addc5ddSAl Viro 1245addc5ddSAl Viro static void __touch_namespace(struct namespace *ns) 1255addc5ddSAl Viro { 1265addc5ddSAl Viro if (ns && ns->event != event) { 1275addc5ddSAl Viro ns->event = event; 1285addc5ddSAl Viro wake_up_interruptible(&ns->poll); 1295addc5ddSAl Viro } 1305addc5ddSAl Viro } 1315addc5ddSAl Viro 1321da177e4SLinus Torvalds static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) 1331da177e4SLinus Torvalds { 1341da177e4SLinus Torvalds old_nd->dentry = mnt->mnt_mountpoint; 1351da177e4SLinus Torvalds old_nd->mnt = mnt->mnt_parent; 1361da177e4SLinus Torvalds mnt->mnt_parent = mnt; 1371da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 1381da177e4SLinus Torvalds list_del_init(&mnt->mnt_child); 1391da177e4SLinus Torvalds list_del_init(&mnt->mnt_hash); 1401da177e4SLinus Torvalds old_nd->dentry->d_mounted--; 1411da177e4SLinus Torvalds } 1421da177e4SLinus Torvalds 1431da177e4SLinus Torvalds static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) 1441da177e4SLinus Torvalds { 1451da177e4SLinus Torvalds mnt->mnt_parent = mntget(nd->mnt); 1461da177e4SLinus Torvalds mnt->mnt_mountpoint = dget(nd->dentry); 1471da177e4SLinus Torvalds list_add(&mnt->mnt_hash, mount_hashtable + hash(nd->mnt, nd->dentry)); 1481da177e4SLinus Torvalds list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); 1491da177e4SLinus Torvalds nd->dentry->d_mounted++; 1501da177e4SLinus Torvalds } 1511da177e4SLinus Torvalds 1521da177e4SLinus Torvalds static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) 1531da177e4SLinus Torvalds { 1541da177e4SLinus Torvalds struct list_head *next = p->mnt_mounts.next; 1551da177e4SLinus Torvalds if (next == &p->mnt_mounts) { 1561da177e4SLinus Torvalds while (1) { 1571da177e4SLinus Torvalds if (p == root) 1581da177e4SLinus Torvalds return NULL; 1591da177e4SLinus Torvalds next = p->mnt_child.next; 1601da177e4SLinus Torvalds if (next != &p->mnt_parent->mnt_mounts) 1611da177e4SLinus Torvalds break; 1621da177e4SLinus Torvalds p = p->mnt_parent; 1631da177e4SLinus Torvalds } 1641da177e4SLinus Torvalds } 1651da177e4SLinus Torvalds return list_entry(next, struct vfsmount, mnt_child); 1661da177e4SLinus Torvalds } 1671da177e4SLinus Torvalds 168b58fed8bSRam Pai static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root) 1691da177e4SLinus Torvalds { 1701da177e4SLinus Torvalds struct super_block *sb = old->mnt_sb; 1711da177e4SLinus Torvalds struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); 1721da177e4SLinus Torvalds 1731da177e4SLinus Torvalds if (mnt) { 1741da177e4SLinus Torvalds mnt->mnt_flags = old->mnt_flags; 1751da177e4SLinus Torvalds atomic_inc(&sb->s_active); 1761da177e4SLinus Torvalds mnt->mnt_sb = sb; 1771da177e4SLinus Torvalds mnt->mnt_root = dget(root); 1781da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 1791da177e4SLinus Torvalds mnt->mnt_parent = mnt; 18068b47139SMiklos Szeredi mnt->mnt_namespace = current->namespace; 1811da177e4SLinus Torvalds 1821da177e4SLinus Torvalds /* stick the duplicate mount on the same expiry list 1831da177e4SLinus Torvalds * as the original if that was on one */ 1841da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 18555e700b9SMiklos Szeredi if (!list_empty(&old->mnt_expire)) 18655e700b9SMiklos Szeredi list_add(&mnt->mnt_expire, &old->mnt_expire); 1871da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1881da177e4SLinus Torvalds } 1891da177e4SLinus Torvalds return mnt; 1901da177e4SLinus Torvalds } 1911da177e4SLinus Torvalds 1927b7b1aceSAl Viro static inline void __mntput(struct vfsmount *mnt) 1931da177e4SLinus Torvalds { 1941da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 1951da177e4SLinus Torvalds dput(mnt->mnt_root); 1961da177e4SLinus Torvalds free_vfsmnt(mnt); 1971da177e4SLinus Torvalds deactivate_super(sb); 1981da177e4SLinus Torvalds } 1991da177e4SLinus Torvalds 2007b7b1aceSAl Viro void mntput_no_expire(struct vfsmount *mnt) 2017b7b1aceSAl Viro { 2027b7b1aceSAl Viro repeat: 2037b7b1aceSAl Viro if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { 2047b7b1aceSAl Viro if (likely(!mnt->mnt_pinned)) { 2057b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2067b7b1aceSAl Viro __mntput(mnt); 2077b7b1aceSAl Viro return; 2087b7b1aceSAl Viro } 2097b7b1aceSAl Viro atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); 2107b7b1aceSAl Viro mnt->mnt_pinned = 0; 2117b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2127b7b1aceSAl Viro acct_auto_close_mnt(mnt); 2137b7b1aceSAl Viro security_sb_umount_close(mnt); 2147b7b1aceSAl Viro goto repeat; 2157b7b1aceSAl Viro } 2167b7b1aceSAl Viro } 2177b7b1aceSAl Viro 2187b7b1aceSAl Viro EXPORT_SYMBOL(mntput_no_expire); 2197b7b1aceSAl Viro 2207b7b1aceSAl Viro void mnt_pin(struct vfsmount *mnt) 2217b7b1aceSAl Viro { 2227b7b1aceSAl Viro spin_lock(&vfsmount_lock); 2237b7b1aceSAl Viro mnt->mnt_pinned++; 2247b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2257b7b1aceSAl Viro } 2267b7b1aceSAl Viro 2277b7b1aceSAl Viro EXPORT_SYMBOL(mnt_pin); 2287b7b1aceSAl Viro 2297b7b1aceSAl Viro void mnt_unpin(struct vfsmount *mnt) 2307b7b1aceSAl Viro { 2317b7b1aceSAl Viro spin_lock(&vfsmount_lock); 2327b7b1aceSAl Viro if (mnt->mnt_pinned) { 2337b7b1aceSAl Viro atomic_inc(&mnt->mnt_count); 2347b7b1aceSAl Viro mnt->mnt_pinned--; 2357b7b1aceSAl Viro } 2367b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2377b7b1aceSAl Viro } 2387b7b1aceSAl Viro 2397b7b1aceSAl Viro EXPORT_SYMBOL(mnt_unpin); 2401da177e4SLinus Torvalds 2411da177e4SLinus Torvalds /* iterator */ 2421da177e4SLinus Torvalds static void *m_start(struct seq_file *m, loff_t *pos) 2431da177e4SLinus Torvalds { 2441da177e4SLinus Torvalds struct namespace *n = m->private; 2451da177e4SLinus Torvalds struct list_head *p; 2461da177e4SLinus Torvalds loff_t l = *pos; 2471da177e4SLinus Torvalds 2481da177e4SLinus Torvalds down_read(&n->sem); 2491da177e4SLinus Torvalds list_for_each(p, &n->list) 2501da177e4SLinus Torvalds if (!l--) 2511da177e4SLinus Torvalds return list_entry(p, struct vfsmount, mnt_list); 2521da177e4SLinus Torvalds return NULL; 2531da177e4SLinus Torvalds } 2541da177e4SLinus Torvalds 2551da177e4SLinus Torvalds static void *m_next(struct seq_file *m, void *v, loff_t *pos) 2561da177e4SLinus Torvalds { 2571da177e4SLinus Torvalds struct namespace *n = m->private; 2581da177e4SLinus Torvalds struct list_head *p = ((struct vfsmount *)v)->mnt_list.next; 2591da177e4SLinus Torvalds (*pos)++; 2601da177e4SLinus Torvalds return p == &n->list ? NULL : list_entry(p, struct vfsmount, mnt_list); 2611da177e4SLinus Torvalds } 2621da177e4SLinus Torvalds 2631da177e4SLinus Torvalds static void m_stop(struct seq_file *m, void *v) 2641da177e4SLinus Torvalds { 2651da177e4SLinus Torvalds struct namespace *n = m->private; 2661da177e4SLinus Torvalds up_read(&n->sem); 2671da177e4SLinus Torvalds } 2681da177e4SLinus Torvalds 2691da177e4SLinus Torvalds static inline void mangle(struct seq_file *m, const char *s) 2701da177e4SLinus Torvalds { 2711da177e4SLinus Torvalds seq_escape(m, s, " \t\n\\"); 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds 2741da177e4SLinus Torvalds static int show_vfsmnt(struct seq_file *m, void *v) 2751da177e4SLinus Torvalds { 2761da177e4SLinus Torvalds struct vfsmount *mnt = v; 2771da177e4SLinus Torvalds int err = 0; 2781da177e4SLinus Torvalds static struct proc_fs_info { 2791da177e4SLinus Torvalds int flag; 2801da177e4SLinus Torvalds char *str; 2811da177e4SLinus Torvalds } fs_info[] = { 2821da177e4SLinus Torvalds { MS_SYNCHRONOUS, ",sync" }, 2831da177e4SLinus Torvalds { MS_DIRSYNC, ",dirsync" }, 2841da177e4SLinus Torvalds { MS_MANDLOCK, ",mand" }, 2851da177e4SLinus Torvalds { MS_NOATIME, ",noatime" }, 2861da177e4SLinus Torvalds { MS_NODIRATIME, ",nodiratime" }, 2871da177e4SLinus Torvalds { 0, NULL } 2881da177e4SLinus Torvalds }; 2891da177e4SLinus Torvalds static struct proc_fs_info mnt_info[] = { 2901da177e4SLinus Torvalds { MNT_NOSUID, ",nosuid" }, 2911da177e4SLinus Torvalds { MNT_NODEV, ",nodev" }, 2921da177e4SLinus Torvalds { MNT_NOEXEC, ",noexec" }, 2931da177e4SLinus Torvalds { 0, NULL } 2941da177e4SLinus Torvalds }; 2951da177e4SLinus Torvalds struct proc_fs_info *fs_infop; 2961da177e4SLinus Torvalds 2971da177e4SLinus Torvalds mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); 2981da177e4SLinus Torvalds seq_putc(m, ' '); 2991da177e4SLinus Torvalds seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); 3001da177e4SLinus Torvalds seq_putc(m, ' '); 3011da177e4SLinus Torvalds mangle(m, mnt->mnt_sb->s_type->name); 3021da177e4SLinus Torvalds seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); 3031da177e4SLinus Torvalds for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { 3041da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & fs_infop->flag) 3051da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 3061da177e4SLinus Torvalds } 3071da177e4SLinus Torvalds for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { 3081da177e4SLinus Torvalds if (mnt->mnt_flags & fs_infop->flag) 3091da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 3101da177e4SLinus Torvalds } 3111da177e4SLinus Torvalds if (mnt->mnt_sb->s_op->show_options) 3121da177e4SLinus Torvalds err = mnt->mnt_sb->s_op->show_options(m, mnt); 3131da177e4SLinus Torvalds seq_puts(m, " 0 0\n"); 3141da177e4SLinus Torvalds return err; 3151da177e4SLinus Torvalds } 3161da177e4SLinus Torvalds 3171da177e4SLinus Torvalds struct seq_operations mounts_op = { 3181da177e4SLinus Torvalds .start = m_start, 3191da177e4SLinus Torvalds .next = m_next, 3201da177e4SLinus Torvalds .stop = m_stop, 3211da177e4SLinus Torvalds .show = show_vfsmnt 3221da177e4SLinus Torvalds }; 3231da177e4SLinus Torvalds 3241da177e4SLinus Torvalds /** 3251da177e4SLinus Torvalds * may_umount_tree - check if a mount tree is busy 3261da177e4SLinus Torvalds * @mnt: root of mount tree 3271da177e4SLinus Torvalds * 3281da177e4SLinus Torvalds * This is called to check if a tree of mounts has any 3291da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts that are 3301da177e4SLinus Torvalds * busy. 3311da177e4SLinus Torvalds */ 3321da177e4SLinus Torvalds int may_umount_tree(struct vfsmount *mnt) 3331da177e4SLinus Torvalds { 3341da177e4SLinus Torvalds struct list_head *next; 3351da177e4SLinus Torvalds struct vfsmount *this_parent = mnt; 3361da177e4SLinus Torvalds int actual_refs; 3371da177e4SLinus Torvalds int minimum_refs; 3381da177e4SLinus Torvalds 3391da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 3401da177e4SLinus Torvalds actual_refs = atomic_read(&mnt->mnt_count); 3411da177e4SLinus Torvalds minimum_refs = 2; 3421da177e4SLinus Torvalds repeat: 3431da177e4SLinus Torvalds next = this_parent->mnt_mounts.next; 3441da177e4SLinus Torvalds resume: 3451da177e4SLinus Torvalds while (next != &this_parent->mnt_mounts) { 346b58fed8bSRam Pai struct vfsmount *p = 347b58fed8bSRam Pai list_entry(next, struct vfsmount, mnt_child); 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds next = next->next; 3501da177e4SLinus Torvalds 3511da177e4SLinus Torvalds actual_refs += atomic_read(&p->mnt_count); 3521da177e4SLinus Torvalds minimum_refs += 2; 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds if (!list_empty(&p->mnt_mounts)) { 3551da177e4SLinus Torvalds this_parent = p; 3561da177e4SLinus Torvalds goto repeat; 3571da177e4SLinus Torvalds } 3581da177e4SLinus Torvalds } 3591da177e4SLinus Torvalds 3601da177e4SLinus Torvalds if (this_parent != mnt) { 3611da177e4SLinus Torvalds next = this_parent->mnt_child.next; 3621da177e4SLinus Torvalds this_parent = this_parent->mnt_parent; 3631da177e4SLinus Torvalds goto resume; 3641da177e4SLinus Torvalds } 3651da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 3661da177e4SLinus Torvalds 3671da177e4SLinus Torvalds if (actual_refs > minimum_refs) 3681da177e4SLinus Torvalds return -EBUSY; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return 0; 3711da177e4SLinus Torvalds } 3721da177e4SLinus Torvalds 3731da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount_tree); 3741da177e4SLinus Torvalds 3751da177e4SLinus Torvalds /** 3761da177e4SLinus Torvalds * may_umount - check if a mount point is busy 3771da177e4SLinus Torvalds * @mnt: root of mount 3781da177e4SLinus Torvalds * 3791da177e4SLinus Torvalds * This is called to check if a mount point has any 3801da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts. If the 3811da177e4SLinus Torvalds * mount has sub mounts this will return busy 3821da177e4SLinus Torvalds * regardless of whether the sub mounts are busy. 3831da177e4SLinus Torvalds * 3841da177e4SLinus Torvalds * Doesn't take quota and stuff into account. IOW, in some cases it will 3851da177e4SLinus Torvalds * give false negatives. The main reason why it's here is that we need 3861da177e4SLinus Torvalds * a non-destructive way to look for easily umountable filesystems. 3871da177e4SLinus Torvalds */ 3881da177e4SLinus Torvalds int may_umount(struct vfsmount *mnt) 3891da177e4SLinus Torvalds { 3901da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) > 2) 3911da177e4SLinus Torvalds return -EBUSY; 3921da177e4SLinus Torvalds return 0; 3931da177e4SLinus Torvalds } 3941da177e4SLinus Torvalds 3951da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount); 3961da177e4SLinus Torvalds 39752c1da39SAdrian Bunk static void umount_tree(struct vfsmount *mnt) 3981da177e4SLinus Torvalds { 3991da177e4SLinus Torvalds struct vfsmount *p; 4001da177e4SLinus Torvalds LIST_HEAD(kill); 4011da177e4SLinus Torvalds 4021da177e4SLinus Torvalds for (p = mnt; p; p = next_mnt(p, mnt)) { 4031da177e4SLinus Torvalds list_del(&p->mnt_list); 4041da177e4SLinus Torvalds list_add(&p->mnt_list, &kill); 4055addc5ddSAl Viro __touch_namespace(p->mnt_namespace); 406202322e6SMiklos Szeredi p->mnt_namespace = NULL; 4071da177e4SLinus Torvalds } 4081da177e4SLinus Torvalds 4091da177e4SLinus Torvalds while (!list_empty(&kill)) { 4101da177e4SLinus Torvalds mnt = list_entry(kill.next, struct vfsmount, mnt_list); 4111da177e4SLinus Torvalds list_del_init(&mnt->mnt_list); 41255e700b9SMiklos Szeredi list_del_init(&mnt->mnt_expire); 4131da177e4SLinus Torvalds if (mnt->mnt_parent == mnt) { 4141da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 4151da177e4SLinus Torvalds } else { 4161da177e4SLinus Torvalds struct nameidata old_nd; 4171da177e4SLinus Torvalds detach_mnt(mnt, &old_nd); 4181da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 4191da177e4SLinus Torvalds path_release(&old_nd); 4201da177e4SLinus Torvalds } 4211da177e4SLinus Torvalds mntput(mnt); 4221da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 4231da177e4SLinus Torvalds } 4241da177e4SLinus Torvalds } 4251da177e4SLinus Torvalds 4261da177e4SLinus Torvalds static int do_umount(struct vfsmount *mnt, int flags) 4271da177e4SLinus Torvalds { 4281da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 4291da177e4SLinus Torvalds int retval; 4301da177e4SLinus Torvalds 4311da177e4SLinus Torvalds retval = security_sb_umount(mnt, flags); 4321da177e4SLinus Torvalds if (retval) 4331da177e4SLinus Torvalds return retval; 4341da177e4SLinus Torvalds 4351da177e4SLinus Torvalds /* 4361da177e4SLinus Torvalds * Allow userspace to request a mountpoint be expired rather than 4371da177e4SLinus Torvalds * unmounting unconditionally. Unmount only happens if: 4381da177e4SLinus Torvalds * (1) the mark is already set (the mark is cleared by mntput()) 4391da177e4SLinus Torvalds * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] 4401da177e4SLinus Torvalds */ 4411da177e4SLinus Torvalds if (flags & MNT_EXPIRE) { 4421da177e4SLinus Torvalds if (mnt == current->fs->rootmnt || 4431da177e4SLinus Torvalds flags & (MNT_FORCE | MNT_DETACH)) 4441da177e4SLinus Torvalds return -EINVAL; 4451da177e4SLinus Torvalds 4461da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) != 2) 4471da177e4SLinus Torvalds return -EBUSY; 4481da177e4SLinus Torvalds 4491da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1)) 4501da177e4SLinus Torvalds return -EAGAIN; 4511da177e4SLinus Torvalds } 4521da177e4SLinus Torvalds 4531da177e4SLinus Torvalds /* 4541da177e4SLinus Torvalds * If we may have to abort operations to get out of this 4551da177e4SLinus Torvalds * mount, and they will themselves hold resources we must 4561da177e4SLinus Torvalds * allow the fs to do things. In the Unix tradition of 4571da177e4SLinus Torvalds * 'Gee thats tricky lets do it in userspace' the umount_begin 4581da177e4SLinus Torvalds * might fail to complete on the first run through as other tasks 4591da177e4SLinus Torvalds * must return, and the like. Thats for the mount program to worry 4601da177e4SLinus Torvalds * about for the moment. 4611da177e4SLinus Torvalds */ 4621da177e4SLinus Torvalds 4631da177e4SLinus Torvalds lock_kernel(); 4641da177e4SLinus Torvalds if ((flags & MNT_FORCE) && sb->s_op->umount_begin) 4651da177e4SLinus Torvalds sb->s_op->umount_begin(sb); 4661da177e4SLinus Torvalds unlock_kernel(); 4671da177e4SLinus Torvalds 4681da177e4SLinus Torvalds /* 4691da177e4SLinus Torvalds * No sense to grab the lock for this test, but test itself looks 4701da177e4SLinus Torvalds * somewhat bogus. Suggestions for better replacement? 4711da177e4SLinus Torvalds * Ho-hum... In principle, we might treat that as umount + switch 4721da177e4SLinus Torvalds * to rootfs. GC would eventually take care of the old vfsmount. 4731da177e4SLinus Torvalds * Actually it makes sense, especially if rootfs would contain a 4741da177e4SLinus Torvalds * /reboot - static binary that would close all descriptors and 4751da177e4SLinus Torvalds * call reboot(9). Then init(8) could umount root and exec /reboot. 4761da177e4SLinus Torvalds */ 4771da177e4SLinus Torvalds if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { 4781da177e4SLinus Torvalds /* 4791da177e4SLinus Torvalds * Special case for "unmounting" root ... 4801da177e4SLinus Torvalds * we just try to remount it readonly. 4811da177e4SLinus Torvalds */ 4821da177e4SLinus Torvalds down_write(&sb->s_umount); 4831da177e4SLinus Torvalds if (!(sb->s_flags & MS_RDONLY)) { 4841da177e4SLinus Torvalds lock_kernel(); 4851da177e4SLinus Torvalds DQUOT_OFF(sb); 4861da177e4SLinus Torvalds retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); 4871da177e4SLinus Torvalds unlock_kernel(); 4881da177e4SLinus Torvalds } 4891da177e4SLinus Torvalds up_write(&sb->s_umount); 4901da177e4SLinus Torvalds return retval; 4911da177e4SLinus Torvalds } 4921da177e4SLinus Torvalds 4931da177e4SLinus Torvalds down_write(¤t->namespace->sem); 4941da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 4955addc5ddSAl Viro event++; 4961da177e4SLinus Torvalds 4971da177e4SLinus Torvalds retval = -EBUSY; 4981da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) { 4991da177e4SLinus Torvalds if (!list_empty(&mnt->mnt_list)) 5001da177e4SLinus Torvalds umount_tree(mnt); 5011da177e4SLinus Torvalds retval = 0; 5021da177e4SLinus Torvalds } 5031da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 5041da177e4SLinus Torvalds if (retval) 5051da177e4SLinus Torvalds security_sb_umount_busy(mnt); 5061da177e4SLinus Torvalds up_write(¤t->namespace->sem); 5071da177e4SLinus Torvalds return retval; 5081da177e4SLinus Torvalds } 5091da177e4SLinus Torvalds 5101da177e4SLinus Torvalds /* 5111da177e4SLinus Torvalds * Now umount can handle mount points as well as block devices. 5121da177e4SLinus Torvalds * This is important for filesystems which use unnamed block devices. 5131da177e4SLinus Torvalds * 5141da177e4SLinus Torvalds * We now support a flag for forced unmount like the other 'big iron' 5151da177e4SLinus Torvalds * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD 5161da177e4SLinus Torvalds */ 5171da177e4SLinus Torvalds 5181da177e4SLinus Torvalds asmlinkage long sys_umount(char __user * name, int flags) 5191da177e4SLinus Torvalds { 5201da177e4SLinus Torvalds struct nameidata nd; 5211da177e4SLinus Torvalds int retval; 5221da177e4SLinus Torvalds 5231da177e4SLinus Torvalds retval = __user_walk(name, LOOKUP_FOLLOW, &nd); 5241da177e4SLinus Torvalds if (retval) 5251da177e4SLinus Torvalds goto out; 5261da177e4SLinus Torvalds retval = -EINVAL; 5271da177e4SLinus Torvalds if (nd.dentry != nd.mnt->mnt_root) 5281da177e4SLinus Torvalds goto dput_and_out; 5291da177e4SLinus Torvalds if (!check_mnt(nd.mnt)) 5301da177e4SLinus Torvalds goto dput_and_out; 5311da177e4SLinus Torvalds 5321da177e4SLinus Torvalds retval = -EPERM; 5331da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 5341da177e4SLinus Torvalds goto dput_and_out; 5351da177e4SLinus Torvalds 5361da177e4SLinus Torvalds retval = do_umount(nd.mnt, flags); 5371da177e4SLinus Torvalds dput_and_out: 5381da177e4SLinus Torvalds path_release_on_umount(&nd); 5391da177e4SLinus Torvalds out: 5401da177e4SLinus Torvalds return retval; 5411da177e4SLinus Torvalds } 5421da177e4SLinus Torvalds 5431da177e4SLinus Torvalds #ifdef __ARCH_WANT_SYS_OLDUMOUNT 5441da177e4SLinus Torvalds 5451da177e4SLinus Torvalds /* 5461da177e4SLinus Torvalds * The 2.0 compatible umount. No flags. 5471da177e4SLinus Torvalds */ 5481da177e4SLinus Torvalds asmlinkage long sys_oldumount(char __user * name) 5491da177e4SLinus Torvalds { 5501da177e4SLinus Torvalds return sys_umount(name, 0); 5511da177e4SLinus Torvalds } 5521da177e4SLinus Torvalds 5531da177e4SLinus Torvalds #endif 5541da177e4SLinus Torvalds 5551da177e4SLinus Torvalds static int mount_is_safe(struct nameidata *nd) 5561da177e4SLinus Torvalds { 5571da177e4SLinus Torvalds if (capable(CAP_SYS_ADMIN)) 5581da177e4SLinus Torvalds return 0; 5591da177e4SLinus Torvalds return -EPERM; 5601da177e4SLinus Torvalds #ifdef notyet 5611da177e4SLinus Torvalds if (S_ISLNK(nd->dentry->d_inode->i_mode)) 5621da177e4SLinus Torvalds return -EPERM; 5631da177e4SLinus Torvalds if (nd->dentry->d_inode->i_mode & S_ISVTX) { 5641da177e4SLinus Torvalds if (current->uid != nd->dentry->d_inode->i_uid) 5651da177e4SLinus Torvalds return -EPERM; 5661da177e4SLinus Torvalds } 5671da177e4SLinus Torvalds if (permission(nd->dentry->d_inode, MAY_WRITE, nd)) 5681da177e4SLinus Torvalds return -EPERM; 5691da177e4SLinus Torvalds return 0; 5701da177e4SLinus Torvalds #endif 5711da177e4SLinus Torvalds } 5721da177e4SLinus Torvalds 573b58fed8bSRam Pai static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) 5741da177e4SLinus Torvalds { 5751da177e4SLinus Torvalds while (1) { 5761da177e4SLinus Torvalds if (d == dentry) 5771da177e4SLinus Torvalds return 1; 5781da177e4SLinus Torvalds if (d == NULL || d == d->d_parent) 5791da177e4SLinus Torvalds return 0; 5801da177e4SLinus Torvalds d = d->d_parent; 5811da177e4SLinus Torvalds } 5821da177e4SLinus Torvalds } 5831da177e4SLinus Torvalds 5841da177e4SLinus Torvalds static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry) 5851da177e4SLinus Torvalds { 5861da177e4SLinus Torvalds struct vfsmount *res, *p, *q, *r, *s; 5871da177e4SLinus Torvalds struct nameidata nd; 5881da177e4SLinus Torvalds 5891da177e4SLinus Torvalds res = q = clone_mnt(mnt, dentry); 5901da177e4SLinus Torvalds if (!q) 5911da177e4SLinus Torvalds goto Enomem; 5921da177e4SLinus Torvalds q->mnt_mountpoint = mnt->mnt_mountpoint; 5931da177e4SLinus Torvalds 5941da177e4SLinus Torvalds p = mnt; 595fdadd65fSDomen Puncer list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { 5961da177e4SLinus Torvalds if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) 5971da177e4SLinus Torvalds continue; 5981da177e4SLinus Torvalds 5991da177e4SLinus Torvalds for (s = r; s; s = next_mnt(s, r)) { 6001da177e4SLinus Torvalds while (p != s->mnt_parent) { 6011da177e4SLinus Torvalds p = p->mnt_parent; 6021da177e4SLinus Torvalds q = q->mnt_parent; 6031da177e4SLinus Torvalds } 6041da177e4SLinus Torvalds p = s; 6051da177e4SLinus Torvalds nd.mnt = q; 6061da177e4SLinus Torvalds nd.dentry = p->mnt_mountpoint; 6071da177e4SLinus Torvalds q = clone_mnt(p, p->mnt_root); 6081da177e4SLinus Torvalds if (!q) 6091da177e4SLinus Torvalds goto Enomem; 6101da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6111da177e4SLinus Torvalds list_add_tail(&q->mnt_list, &res->mnt_list); 6121da177e4SLinus Torvalds attach_mnt(q, &nd); 6131da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds } 6161da177e4SLinus Torvalds return res; 6171da177e4SLinus Torvalds Enomem: 6181da177e4SLinus Torvalds if (res) { 6191da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6201da177e4SLinus Torvalds umount_tree(res); 6211da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6221da177e4SLinus Torvalds } 6231da177e4SLinus Torvalds return NULL; 6241da177e4SLinus Torvalds } 6251da177e4SLinus Torvalds 6261da177e4SLinus Torvalds static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) 6271da177e4SLinus Torvalds { 6281da177e4SLinus Torvalds int err; 6291da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & MS_NOUSER) 6301da177e4SLinus Torvalds return -EINVAL; 6311da177e4SLinus Torvalds 6321da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 6331da177e4SLinus Torvalds S_ISDIR(mnt->mnt_root->d_inode->i_mode)) 6341da177e4SLinus Torvalds return -ENOTDIR; 6351da177e4SLinus Torvalds 6361da177e4SLinus Torvalds err = -ENOENT; 6371da177e4SLinus Torvalds down(&nd->dentry->d_inode->i_sem); 6381da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 6391da177e4SLinus Torvalds goto out_unlock; 6401da177e4SLinus Torvalds 6411da177e4SLinus Torvalds err = security_sb_check_sb(mnt, nd); 6421da177e4SLinus Torvalds if (err) 6431da177e4SLinus Torvalds goto out_unlock; 6441da177e4SLinus Torvalds 6451da177e4SLinus Torvalds err = -ENOENT; 6461da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6471da177e4SLinus Torvalds if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) { 6481da177e4SLinus Torvalds struct list_head head; 6491da177e4SLinus Torvalds 6501da177e4SLinus Torvalds attach_mnt(mnt, nd); 6511da177e4SLinus Torvalds list_add_tail(&head, &mnt->mnt_list); 6521da177e4SLinus Torvalds list_splice(&head, current->namespace->list.prev); 6531da177e4SLinus Torvalds mntget(mnt); 6541da177e4SLinus Torvalds err = 0; 6555addc5ddSAl Viro touch_namespace(current->namespace); 6561da177e4SLinus Torvalds } 6571da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6581da177e4SLinus Torvalds out_unlock: 6591da177e4SLinus Torvalds up(&nd->dentry->d_inode->i_sem); 6601da177e4SLinus Torvalds if (!err) 6611da177e4SLinus Torvalds security_sb_post_addmount(mnt, nd); 6621da177e4SLinus Torvalds return err; 6631da177e4SLinus Torvalds } 6641da177e4SLinus Torvalds 6651da177e4SLinus Torvalds /* 6661da177e4SLinus Torvalds * do loopback mount. 6671da177e4SLinus Torvalds */ 6681da177e4SLinus Torvalds static int do_loopback(struct nameidata *nd, char *old_name, int recurse) 6691da177e4SLinus Torvalds { 6701da177e4SLinus Torvalds struct nameidata old_nd; 6711da177e4SLinus Torvalds struct vfsmount *mnt = NULL; 6721da177e4SLinus Torvalds int err = mount_is_safe(nd); 6731da177e4SLinus Torvalds if (err) 6741da177e4SLinus Torvalds return err; 6751da177e4SLinus Torvalds if (!old_name || !*old_name) 6761da177e4SLinus Torvalds return -EINVAL; 6771da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 6781da177e4SLinus Torvalds if (err) 6791da177e4SLinus Torvalds return err; 6801da177e4SLinus Torvalds 6811da177e4SLinus Torvalds down_write(¤t->namespace->sem); 6821da177e4SLinus Torvalds err = -EINVAL; 683ccd48bc7SAl Viro if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) 684ccd48bc7SAl Viro goto out; 685ccd48bc7SAl Viro 6861da177e4SLinus Torvalds err = -ENOMEM; 6871da177e4SLinus Torvalds if (recurse) 6881da177e4SLinus Torvalds mnt = copy_tree(old_nd.mnt, old_nd.dentry); 6891da177e4SLinus Torvalds else 6901da177e4SLinus Torvalds mnt = clone_mnt(old_nd.mnt, old_nd.dentry); 6911da177e4SLinus Torvalds 692ccd48bc7SAl Viro if (!mnt) 693ccd48bc7SAl Viro goto out; 694ccd48bc7SAl Viro 6951da177e4SLinus Torvalds /* stop bind mounts from expiring */ 6961da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 69755e700b9SMiklos Szeredi list_del_init(&mnt->mnt_expire); 6981da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6991da177e4SLinus Torvalds 7001da177e4SLinus Torvalds err = graft_tree(mnt, nd); 7011da177e4SLinus Torvalds if (err) { 7021da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7031da177e4SLinus Torvalds umount_tree(mnt); 7041da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7051da177e4SLinus Torvalds } else 7061da177e4SLinus Torvalds mntput(mnt); 7071da177e4SLinus Torvalds 708ccd48bc7SAl Viro out: 7091da177e4SLinus Torvalds up_write(¤t->namespace->sem); 7101da177e4SLinus Torvalds path_release(&old_nd); 7111da177e4SLinus Torvalds return err; 7121da177e4SLinus Torvalds } 7131da177e4SLinus Torvalds 7141da177e4SLinus Torvalds /* 7151da177e4SLinus Torvalds * change filesystem flags. dir should be a physical root of filesystem. 7161da177e4SLinus Torvalds * If you've mounted a non-root directory somewhere and want to do remount 7171da177e4SLinus Torvalds * on it - tough luck. 7181da177e4SLinus Torvalds */ 7191da177e4SLinus Torvalds static int do_remount(struct nameidata *nd, int flags, int mnt_flags, 7201da177e4SLinus Torvalds void *data) 7211da177e4SLinus Torvalds { 7221da177e4SLinus Torvalds int err; 7231da177e4SLinus Torvalds struct super_block *sb = nd->mnt->mnt_sb; 7241da177e4SLinus Torvalds 7251da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 7261da177e4SLinus Torvalds return -EPERM; 7271da177e4SLinus Torvalds 7281da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 7291da177e4SLinus Torvalds return -EINVAL; 7301da177e4SLinus Torvalds 7311da177e4SLinus Torvalds if (nd->dentry != nd->mnt->mnt_root) 7321da177e4SLinus Torvalds return -EINVAL; 7331da177e4SLinus Torvalds 7341da177e4SLinus Torvalds down_write(&sb->s_umount); 7351da177e4SLinus Torvalds err = do_remount_sb(sb, flags, data, 0); 7361da177e4SLinus Torvalds if (!err) 7371da177e4SLinus Torvalds nd->mnt->mnt_flags = mnt_flags; 7381da177e4SLinus Torvalds up_write(&sb->s_umount); 7391da177e4SLinus Torvalds if (!err) 7401da177e4SLinus Torvalds security_sb_post_remount(nd->mnt, flags, data); 7411da177e4SLinus Torvalds return err; 7421da177e4SLinus Torvalds } 7431da177e4SLinus Torvalds 7441da177e4SLinus Torvalds static int do_move_mount(struct nameidata *nd, char *old_name) 7451da177e4SLinus Torvalds { 7461da177e4SLinus Torvalds struct nameidata old_nd, parent_nd; 7471da177e4SLinus Torvalds struct vfsmount *p; 7481da177e4SLinus Torvalds int err = 0; 7491da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 7501da177e4SLinus Torvalds return -EPERM; 7511da177e4SLinus Torvalds if (!old_name || !*old_name) 7521da177e4SLinus Torvalds return -EINVAL; 7531da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 7541da177e4SLinus Torvalds if (err) 7551da177e4SLinus Torvalds return err; 7561da177e4SLinus Torvalds 7571da177e4SLinus Torvalds down_write(¤t->namespace->sem); 7581da177e4SLinus Torvalds while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 7591da177e4SLinus Torvalds ; 7601da177e4SLinus Torvalds err = -EINVAL; 7611da177e4SLinus Torvalds if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) 7621da177e4SLinus Torvalds goto out; 7631da177e4SLinus Torvalds 7641da177e4SLinus Torvalds err = -ENOENT; 7651da177e4SLinus Torvalds down(&nd->dentry->d_inode->i_sem); 7661da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 7671da177e4SLinus Torvalds goto out1; 7681da177e4SLinus Torvalds 7691da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7701da177e4SLinus Torvalds if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) 7711da177e4SLinus Torvalds goto out2; 7721da177e4SLinus Torvalds 7731da177e4SLinus Torvalds err = -EINVAL; 7741da177e4SLinus Torvalds if (old_nd.dentry != old_nd.mnt->mnt_root) 7751da177e4SLinus Torvalds goto out2; 7761da177e4SLinus Torvalds 7771da177e4SLinus Torvalds if (old_nd.mnt == old_nd.mnt->mnt_parent) 7781da177e4SLinus Torvalds goto out2; 7791da177e4SLinus Torvalds 7801da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 7811da177e4SLinus Torvalds S_ISDIR(old_nd.dentry->d_inode->i_mode)) 7821da177e4SLinus Torvalds goto out2; 7831da177e4SLinus Torvalds 7841da177e4SLinus Torvalds err = -ELOOP; 7851da177e4SLinus Torvalds for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) 7861da177e4SLinus Torvalds if (p == old_nd.mnt) 7871da177e4SLinus Torvalds goto out2; 7881da177e4SLinus Torvalds err = 0; 7891da177e4SLinus Torvalds 7901da177e4SLinus Torvalds detach_mnt(old_nd.mnt, &parent_nd); 7911da177e4SLinus Torvalds attach_mnt(old_nd.mnt, nd); 7925addc5ddSAl Viro touch_namespace(current->namespace); 7931da177e4SLinus Torvalds 7941da177e4SLinus Torvalds /* if the mount is moved, it should no longer be expire 7951da177e4SLinus Torvalds * automatically */ 79655e700b9SMiklos Szeredi list_del_init(&old_nd.mnt->mnt_expire); 7971da177e4SLinus Torvalds out2: 7981da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7991da177e4SLinus Torvalds out1: 8001da177e4SLinus Torvalds up(&nd->dentry->d_inode->i_sem); 8011da177e4SLinus Torvalds out: 8021da177e4SLinus Torvalds up_write(¤t->namespace->sem); 8031da177e4SLinus Torvalds if (!err) 8041da177e4SLinus Torvalds path_release(&parent_nd); 8051da177e4SLinus Torvalds path_release(&old_nd); 8061da177e4SLinus Torvalds return err; 8071da177e4SLinus Torvalds } 8081da177e4SLinus Torvalds 8091da177e4SLinus Torvalds /* 8101da177e4SLinus Torvalds * create a new mount for userspace and request it to be added into the 8111da177e4SLinus Torvalds * namespace's tree 8121da177e4SLinus Torvalds */ 8131da177e4SLinus Torvalds static int do_new_mount(struct nameidata *nd, char *type, int flags, 8141da177e4SLinus Torvalds int mnt_flags, char *name, void *data) 8151da177e4SLinus Torvalds { 8161da177e4SLinus Torvalds struct vfsmount *mnt; 8171da177e4SLinus Torvalds 8181da177e4SLinus Torvalds if (!type || !memchr(type, 0, PAGE_SIZE)) 8191da177e4SLinus Torvalds return -EINVAL; 8201da177e4SLinus Torvalds 8211da177e4SLinus Torvalds /* we need capabilities... */ 8221da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 8231da177e4SLinus Torvalds return -EPERM; 8241da177e4SLinus Torvalds 8251da177e4SLinus Torvalds mnt = do_kern_mount(type, flags, name, data); 8261da177e4SLinus Torvalds if (IS_ERR(mnt)) 8271da177e4SLinus Torvalds return PTR_ERR(mnt); 8281da177e4SLinus Torvalds 8291da177e4SLinus Torvalds return do_add_mount(mnt, nd, mnt_flags, NULL); 8301da177e4SLinus Torvalds } 8311da177e4SLinus Torvalds 8321da177e4SLinus Torvalds /* 8331da177e4SLinus Torvalds * add a mount into a namespace's mount tree 8341da177e4SLinus Torvalds * - provide the option of adding the new mount to an expiration list 8351da177e4SLinus Torvalds */ 8361da177e4SLinus Torvalds int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, 8371da177e4SLinus Torvalds int mnt_flags, struct list_head *fslist) 8381da177e4SLinus Torvalds { 8391da177e4SLinus Torvalds int err; 8401da177e4SLinus Torvalds 8411da177e4SLinus Torvalds down_write(¤t->namespace->sem); 8421da177e4SLinus Torvalds /* Something was mounted here while we slept */ 8431da177e4SLinus Torvalds while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 8441da177e4SLinus Torvalds ; 8451da177e4SLinus Torvalds err = -EINVAL; 8461da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 8471da177e4SLinus Torvalds goto unlock; 8481da177e4SLinus Torvalds 8491da177e4SLinus Torvalds /* Refuse the same filesystem on the same mount point */ 8501da177e4SLinus Torvalds err = -EBUSY; 8511da177e4SLinus Torvalds if (nd->mnt->mnt_sb == newmnt->mnt_sb && 8521da177e4SLinus Torvalds nd->mnt->mnt_root == nd->dentry) 8531da177e4SLinus Torvalds goto unlock; 8541da177e4SLinus Torvalds 8551da177e4SLinus Torvalds err = -EINVAL; 8561da177e4SLinus Torvalds if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) 8571da177e4SLinus Torvalds goto unlock; 8581da177e4SLinus Torvalds 8591da177e4SLinus Torvalds newmnt->mnt_flags = mnt_flags; 860484e389cSMiklos Szeredi newmnt->mnt_namespace = current->namespace; 8611da177e4SLinus Torvalds err = graft_tree(newmnt, nd); 8621da177e4SLinus Torvalds 8631da177e4SLinus Torvalds if (err == 0 && fslist) { 8641da177e4SLinus Torvalds /* add to the specified expiration list */ 8651da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 86655e700b9SMiklos Szeredi list_add_tail(&newmnt->mnt_expire, fslist); 8671da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 8681da177e4SLinus Torvalds } 8691da177e4SLinus Torvalds 8701da177e4SLinus Torvalds unlock: 8711da177e4SLinus Torvalds up_write(¤t->namespace->sem); 8721da177e4SLinus Torvalds mntput(newmnt); 8731da177e4SLinus Torvalds return err; 8741da177e4SLinus Torvalds } 8751da177e4SLinus Torvalds 8761da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(do_add_mount); 8771da177e4SLinus Torvalds 87824ca2af1SMiklos Szeredi static void expire_mount(struct vfsmount *mnt, struct list_head *mounts) 87924ca2af1SMiklos Szeredi { 88024ca2af1SMiklos Szeredi spin_lock(&vfsmount_lock); 88124ca2af1SMiklos Szeredi 88224ca2af1SMiklos Szeredi /* 883ed42c879SMiklos Szeredi * Check if mount is still attached, if not, let whoever holds it deal 884ed42c879SMiklos Szeredi * with the sucker 885ed42c879SMiklos Szeredi */ 886ed42c879SMiklos Szeredi if (mnt->mnt_parent == mnt) { 887ed42c879SMiklos Szeredi spin_unlock(&vfsmount_lock); 888ed42c879SMiklos Szeredi return; 889ed42c879SMiklos Szeredi } 890ed42c879SMiklos Szeredi 891ed42c879SMiklos Szeredi /* 89224ca2af1SMiklos Szeredi * Check that it is still dead: the count should now be 2 - as 89324ca2af1SMiklos Szeredi * contributed by the vfsmount parent and the mntget above 89424ca2af1SMiklos Szeredi */ 89524ca2af1SMiklos Szeredi if (atomic_read(&mnt->mnt_count) == 2) { 89624ca2af1SMiklos Szeredi struct nameidata old_nd; 89724ca2af1SMiklos Szeredi 89824ca2af1SMiklos Szeredi /* delete from the namespace */ 8995addc5ddSAl Viro touch_namespace(mnt->mnt_namespace); 90024ca2af1SMiklos Szeredi list_del_init(&mnt->mnt_list); 901ac081153SMiklos Szeredi mnt->mnt_namespace = NULL; 90224ca2af1SMiklos Szeredi detach_mnt(mnt, &old_nd); 90324ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 90424ca2af1SMiklos Szeredi path_release(&old_nd); 90524ca2af1SMiklos Szeredi mntput(mnt); 90624ca2af1SMiklos Szeredi } else { 90724ca2af1SMiklos Szeredi /* 90824ca2af1SMiklos Szeredi * Someone brought it back to life whilst we didn't have any 90924ca2af1SMiklos Szeredi * locks held so return it to the expiration list 91024ca2af1SMiklos Szeredi */ 91155e700b9SMiklos Szeredi list_add_tail(&mnt->mnt_expire, mounts); 91224ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 91324ca2af1SMiklos Szeredi } 91424ca2af1SMiklos Szeredi } 91524ca2af1SMiklos Szeredi 9161da177e4SLinus Torvalds /* 9171da177e4SLinus Torvalds * process a list of expirable mountpoints with the intent of discarding any 9181da177e4SLinus Torvalds * mountpoints that aren't in use and haven't been touched since last we came 9191da177e4SLinus Torvalds * here 9201da177e4SLinus Torvalds */ 9211da177e4SLinus Torvalds void mark_mounts_for_expiry(struct list_head *mounts) 9221da177e4SLinus Torvalds { 9231da177e4SLinus Torvalds struct namespace *namespace; 9241da177e4SLinus Torvalds struct vfsmount *mnt, *next; 9251da177e4SLinus Torvalds LIST_HEAD(graveyard); 9261da177e4SLinus Torvalds 9271da177e4SLinus Torvalds if (list_empty(mounts)) 9281da177e4SLinus Torvalds return; 9291da177e4SLinus Torvalds 9301da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 9311da177e4SLinus Torvalds 9321da177e4SLinus Torvalds /* extract from the expiration list every vfsmount that matches the 9331da177e4SLinus Torvalds * following criteria: 9341da177e4SLinus Torvalds * - only referenced by its parent vfsmount 9351da177e4SLinus Torvalds * - still marked for expiry (marked on the last call here; marks are 9361da177e4SLinus Torvalds * cleared by mntput()) 9371da177e4SLinus Torvalds */ 93855e700b9SMiklos Szeredi list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { 9391da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1) || 9401da177e4SLinus Torvalds atomic_read(&mnt->mnt_count) != 1) 9411da177e4SLinus Torvalds continue; 9421da177e4SLinus Torvalds 9431da177e4SLinus Torvalds mntget(mnt); 94455e700b9SMiklos Szeredi list_move(&mnt->mnt_expire, &graveyard); 9451da177e4SLinus Torvalds } 9461da177e4SLinus Torvalds 9471da177e4SLinus Torvalds /* 9481da177e4SLinus Torvalds * go through the vfsmounts we've just consigned to the graveyard to 9491da177e4SLinus Torvalds * - check that they're still dead 9501da177e4SLinus Torvalds * - delete the vfsmount from the appropriate namespace under lock 9511da177e4SLinus Torvalds * - dispose of the corpse 9521da177e4SLinus Torvalds */ 9531da177e4SLinus Torvalds while (!list_empty(&graveyard)) { 95455e700b9SMiklos Szeredi mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire); 95555e700b9SMiklos Szeredi list_del_init(&mnt->mnt_expire); 9561da177e4SLinus Torvalds 9571da177e4SLinus Torvalds /* don't do anything if the namespace is dead - all the 9581da177e4SLinus Torvalds * vfsmounts from it are going away anyway */ 9591da177e4SLinus Torvalds namespace = mnt->mnt_namespace; 9601ce88cf4SMiklos Szeredi if (!namespace || !namespace->root) 9611da177e4SLinus Torvalds continue; 9621da177e4SLinus Torvalds get_namespace(namespace); 9631da177e4SLinus Torvalds 9641da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 9651da177e4SLinus Torvalds down_write(&namespace->sem); 96624ca2af1SMiklos Szeredi expire_mount(mnt, mounts); 9671da177e4SLinus Torvalds up_write(&namespace->sem); 9681da177e4SLinus Torvalds 9691da177e4SLinus Torvalds mntput(mnt); 9701da177e4SLinus Torvalds put_namespace(namespace); 9711da177e4SLinus Torvalds 9721da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 9731da177e4SLinus Torvalds } 9741da177e4SLinus Torvalds 9751da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 9761da177e4SLinus Torvalds } 9771da177e4SLinus Torvalds 9781da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); 9791da177e4SLinus Torvalds 9801da177e4SLinus Torvalds /* 9811da177e4SLinus Torvalds * Some copy_from_user() implementations do not return the exact number of 9821da177e4SLinus Torvalds * bytes remaining to copy on a fault. But copy_mount_options() requires that. 9831da177e4SLinus Torvalds * Note that this function differs from copy_from_user() in that it will oops 9841da177e4SLinus Torvalds * on bad values of `to', rather than returning a short copy. 9851da177e4SLinus Torvalds */ 986b58fed8bSRam Pai static long exact_copy_from_user(void *to, const void __user * from, 987b58fed8bSRam Pai unsigned long n) 9881da177e4SLinus Torvalds { 9891da177e4SLinus Torvalds char *t = to; 9901da177e4SLinus Torvalds const char __user *f = from; 9911da177e4SLinus Torvalds char c; 9921da177e4SLinus Torvalds 9931da177e4SLinus Torvalds if (!access_ok(VERIFY_READ, from, n)) 9941da177e4SLinus Torvalds return n; 9951da177e4SLinus Torvalds 9961da177e4SLinus Torvalds while (n) { 9971da177e4SLinus Torvalds if (__get_user(c, f)) { 9981da177e4SLinus Torvalds memset(t, 0, n); 9991da177e4SLinus Torvalds break; 10001da177e4SLinus Torvalds } 10011da177e4SLinus Torvalds *t++ = c; 10021da177e4SLinus Torvalds f++; 10031da177e4SLinus Torvalds n--; 10041da177e4SLinus Torvalds } 10051da177e4SLinus Torvalds return n; 10061da177e4SLinus Torvalds } 10071da177e4SLinus Torvalds 10081da177e4SLinus Torvalds int copy_mount_options(const void __user * data, unsigned long *where) 10091da177e4SLinus Torvalds { 10101da177e4SLinus Torvalds int i; 10111da177e4SLinus Torvalds unsigned long page; 10121da177e4SLinus Torvalds unsigned long size; 10131da177e4SLinus Torvalds 10141da177e4SLinus Torvalds *where = 0; 10151da177e4SLinus Torvalds if (!data) 10161da177e4SLinus Torvalds return 0; 10171da177e4SLinus Torvalds 10181da177e4SLinus Torvalds if (!(page = __get_free_page(GFP_KERNEL))) 10191da177e4SLinus Torvalds return -ENOMEM; 10201da177e4SLinus Torvalds 10211da177e4SLinus Torvalds /* We only care that *some* data at the address the user 10221da177e4SLinus Torvalds * gave us is valid. Just in case, we'll zero 10231da177e4SLinus Torvalds * the remainder of the page. 10241da177e4SLinus Torvalds */ 10251da177e4SLinus Torvalds /* copy_from_user cannot cross TASK_SIZE ! */ 10261da177e4SLinus Torvalds size = TASK_SIZE - (unsigned long)data; 10271da177e4SLinus Torvalds if (size > PAGE_SIZE) 10281da177e4SLinus Torvalds size = PAGE_SIZE; 10291da177e4SLinus Torvalds 10301da177e4SLinus Torvalds i = size - exact_copy_from_user((void *)page, data, size); 10311da177e4SLinus Torvalds if (!i) { 10321da177e4SLinus Torvalds free_page(page); 10331da177e4SLinus Torvalds return -EFAULT; 10341da177e4SLinus Torvalds } 10351da177e4SLinus Torvalds if (i != PAGE_SIZE) 10361da177e4SLinus Torvalds memset((char *)page + i, 0, PAGE_SIZE - i); 10371da177e4SLinus Torvalds *where = page; 10381da177e4SLinus Torvalds return 0; 10391da177e4SLinus Torvalds } 10401da177e4SLinus Torvalds 10411da177e4SLinus Torvalds /* 10421da177e4SLinus Torvalds * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to 10431da177e4SLinus Torvalds * be given to the mount() call (ie: read-only, no-dev, no-suid etc). 10441da177e4SLinus Torvalds * 10451da177e4SLinus Torvalds * data is a (void *) that can point to any structure up to 10461da177e4SLinus Torvalds * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent 10471da177e4SLinus Torvalds * information (or be NULL). 10481da177e4SLinus Torvalds * 10491da177e4SLinus Torvalds * Pre-0.97 versions of mount() didn't have a flags word. 10501da177e4SLinus Torvalds * When the flags word was introduced its top half was required 10511da177e4SLinus Torvalds * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. 10521da177e4SLinus Torvalds * Therefore, if this magic number is present, it carries no information 10531da177e4SLinus Torvalds * and must be discarded. 10541da177e4SLinus Torvalds */ 10551da177e4SLinus Torvalds long do_mount(char *dev_name, char *dir_name, char *type_page, 10561da177e4SLinus Torvalds unsigned long flags, void *data_page) 10571da177e4SLinus Torvalds { 10581da177e4SLinus Torvalds struct nameidata nd; 10591da177e4SLinus Torvalds int retval = 0; 10601da177e4SLinus Torvalds int mnt_flags = 0; 10611da177e4SLinus Torvalds 10621da177e4SLinus Torvalds /* Discard magic */ 10631da177e4SLinus Torvalds if ((flags & MS_MGC_MSK) == MS_MGC_VAL) 10641da177e4SLinus Torvalds flags &= ~MS_MGC_MSK; 10651da177e4SLinus Torvalds 10661da177e4SLinus Torvalds /* Basic sanity checks */ 10671da177e4SLinus Torvalds 10681da177e4SLinus Torvalds if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) 10691da177e4SLinus Torvalds return -EINVAL; 10701da177e4SLinus Torvalds if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) 10711da177e4SLinus Torvalds return -EINVAL; 10721da177e4SLinus Torvalds 10731da177e4SLinus Torvalds if (data_page) 10741da177e4SLinus Torvalds ((char *)data_page)[PAGE_SIZE - 1] = 0; 10751da177e4SLinus Torvalds 10761da177e4SLinus Torvalds /* Separate the per-mountpoint flags */ 10771da177e4SLinus Torvalds if (flags & MS_NOSUID) 10781da177e4SLinus Torvalds mnt_flags |= MNT_NOSUID; 10791da177e4SLinus Torvalds if (flags & MS_NODEV) 10801da177e4SLinus Torvalds mnt_flags |= MNT_NODEV; 10811da177e4SLinus Torvalds if (flags & MS_NOEXEC) 10821da177e4SLinus Torvalds mnt_flags |= MNT_NOEXEC; 10831da177e4SLinus Torvalds flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE); 10841da177e4SLinus Torvalds 10851da177e4SLinus Torvalds /* ... and get the mountpoint */ 10861da177e4SLinus Torvalds retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); 10871da177e4SLinus Torvalds if (retval) 10881da177e4SLinus Torvalds return retval; 10891da177e4SLinus Torvalds 10901da177e4SLinus Torvalds retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); 10911da177e4SLinus Torvalds if (retval) 10921da177e4SLinus Torvalds goto dput_out; 10931da177e4SLinus Torvalds 10941da177e4SLinus Torvalds if (flags & MS_REMOUNT) 10951da177e4SLinus Torvalds retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, 10961da177e4SLinus Torvalds data_page); 10971da177e4SLinus Torvalds else if (flags & MS_BIND) 10981da177e4SLinus Torvalds retval = do_loopback(&nd, dev_name, flags & MS_REC); 10991da177e4SLinus Torvalds else if (flags & MS_MOVE) 11001da177e4SLinus Torvalds retval = do_move_mount(&nd, dev_name); 11011da177e4SLinus Torvalds else 11021da177e4SLinus Torvalds retval = do_new_mount(&nd, type_page, flags, mnt_flags, 11031da177e4SLinus Torvalds dev_name, data_page); 11041da177e4SLinus Torvalds dput_out: 11051da177e4SLinus Torvalds path_release(&nd); 11061da177e4SLinus Torvalds return retval; 11071da177e4SLinus Torvalds } 11081da177e4SLinus Torvalds 11091da177e4SLinus Torvalds int copy_namespace(int flags, struct task_struct *tsk) 11101da177e4SLinus Torvalds { 11111da177e4SLinus Torvalds struct namespace *namespace = tsk->namespace; 11121da177e4SLinus Torvalds struct namespace *new_ns; 11131da177e4SLinus Torvalds struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; 11141da177e4SLinus Torvalds struct fs_struct *fs = tsk->fs; 11151da177e4SLinus Torvalds struct vfsmount *p, *q; 11161da177e4SLinus Torvalds 11171da177e4SLinus Torvalds if (!namespace) 11181da177e4SLinus Torvalds return 0; 11191da177e4SLinus Torvalds 11201da177e4SLinus Torvalds get_namespace(namespace); 11211da177e4SLinus Torvalds 11221da177e4SLinus Torvalds if (!(flags & CLONE_NEWNS)) 11231da177e4SLinus Torvalds return 0; 11241da177e4SLinus Torvalds 11251da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) { 11261da177e4SLinus Torvalds put_namespace(namespace); 11271da177e4SLinus Torvalds return -EPERM; 11281da177e4SLinus Torvalds } 11291da177e4SLinus Torvalds 11301da177e4SLinus Torvalds new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL); 11311da177e4SLinus Torvalds if (!new_ns) 11321da177e4SLinus Torvalds goto out; 11331da177e4SLinus Torvalds 11341da177e4SLinus Torvalds atomic_set(&new_ns->count, 1); 11351da177e4SLinus Torvalds init_rwsem(&new_ns->sem); 11361da177e4SLinus Torvalds INIT_LIST_HEAD(&new_ns->list); 11375addc5ddSAl Viro init_waitqueue_head(&new_ns->poll); 11385addc5ddSAl Viro new_ns->event = 0; 11391da177e4SLinus Torvalds 11401da177e4SLinus Torvalds down_write(&tsk->namespace->sem); 11411da177e4SLinus Torvalds /* First pass: copy the tree topology */ 11421da177e4SLinus Torvalds new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root); 11431da177e4SLinus Torvalds if (!new_ns->root) { 11441da177e4SLinus Torvalds up_write(&tsk->namespace->sem); 11451da177e4SLinus Torvalds kfree(new_ns); 11461da177e4SLinus Torvalds goto out; 11471da177e4SLinus Torvalds } 11481da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 11491da177e4SLinus Torvalds list_add_tail(&new_ns->list, &new_ns->root->mnt_list); 11501da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 11511da177e4SLinus Torvalds 11521da177e4SLinus Torvalds /* 11531da177e4SLinus Torvalds * Second pass: switch the tsk->fs->* elements and mark new vfsmounts 11541da177e4SLinus Torvalds * as belonging to new namespace. We have already acquired a private 11551da177e4SLinus Torvalds * fs_struct, so tsk->fs->lock is not needed. 11561da177e4SLinus Torvalds */ 11571da177e4SLinus Torvalds p = namespace->root; 11581da177e4SLinus Torvalds q = new_ns->root; 11591da177e4SLinus Torvalds while (p) { 11601da177e4SLinus Torvalds q->mnt_namespace = new_ns; 11611da177e4SLinus Torvalds if (fs) { 11621da177e4SLinus Torvalds if (p == fs->rootmnt) { 11631da177e4SLinus Torvalds rootmnt = p; 11641da177e4SLinus Torvalds fs->rootmnt = mntget(q); 11651da177e4SLinus Torvalds } 11661da177e4SLinus Torvalds if (p == fs->pwdmnt) { 11671da177e4SLinus Torvalds pwdmnt = p; 11681da177e4SLinus Torvalds fs->pwdmnt = mntget(q); 11691da177e4SLinus Torvalds } 11701da177e4SLinus Torvalds if (p == fs->altrootmnt) { 11711da177e4SLinus Torvalds altrootmnt = p; 11721da177e4SLinus Torvalds fs->altrootmnt = mntget(q); 11731da177e4SLinus Torvalds } 11741da177e4SLinus Torvalds } 11751da177e4SLinus Torvalds p = next_mnt(p, namespace->root); 11761da177e4SLinus Torvalds q = next_mnt(q, new_ns->root); 11771da177e4SLinus Torvalds } 11781da177e4SLinus Torvalds up_write(&tsk->namespace->sem); 11791da177e4SLinus Torvalds 11801da177e4SLinus Torvalds tsk->namespace = new_ns; 11811da177e4SLinus Torvalds 11821da177e4SLinus Torvalds if (rootmnt) 11831da177e4SLinus Torvalds mntput(rootmnt); 11841da177e4SLinus Torvalds if (pwdmnt) 11851da177e4SLinus Torvalds mntput(pwdmnt); 11861da177e4SLinus Torvalds if (altrootmnt) 11871da177e4SLinus Torvalds mntput(altrootmnt); 11881da177e4SLinus Torvalds 11891da177e4SLinus Torvalds put_namespace(namespace); 11901da177e4SLinus Torvalds return 0; 11911da177e4SLinus Torvalds 11921da177e4SLinus Torvalds out: 11931da177e4SLinus Torvalds put_namespace(namespace); 11941da177e4SLinus Torvalds return -ENOMEM; 11951da177e4SLinus Torvalds } 11961da177e4SLinus Torvalds 11971da177e4SLinus Torvalds asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, 11981da177e4SLinus Torvalds char __user * type, unsigned long flags, 11991da177e4SLinus Torvalds void __user * data) 12001da177e4SLinus Torvalds { 12011da177e4SLinus Torvalds int retval; 12021da177e4SLinus Torvalds unsigned long data_page; 12031da177e4SLinus Torvalds unsigned long type_page; 12041da177e4SLinus Torvalds unsigned long dev_page; 12051da177e4SLinus Torvalds char *dir_page; 12061da177e4SLinus Torvalds 12071da177e4SLinus Torvalds retval = copy_mount_options(type, &type_page); 12081da177e4SLinus Torvalds if (retval < 0) 12091da177e4SLinus Torvalds return retval; 12101da177e4SLinus Torvalds 12111da177e4SLinus Torvalds dir_page = getname(dir_name); 12121da177e4SLinus Torvalds retval = PTR_ERR(dir_page); 12131da177e4SLinus Torvalds if (IS_ERR(dir_page)) 12141da177e4SLinus Torvalds goto out1; 12151da177e4SLinus Torvalds 12161da177e4SLinus Torvalds retval = copy_mount_options(dev_name, &dev_page); 12171da177e4SLinus Torvalds if (retval < 0) 12181da177e4SLinus Torvalds goto out2; 12191da177e4SLinus Torvalds 12201da177e4SLinus Torvalds retval = copy_mount_options(data, &data_page); 12211da177e4SLinus Torvalds if (retval < 0) 12221da177e4SLinus Torvalds goto out3; 12231da177e4SLinus Torvalds 12241da177e4SLinus Torvalds lock_kernel(); 12251da177e4SLinus Torvalds retval = do_mount((char *)dev_page, dir_page, (char *)type_page, 12261da177e4SLinus Torvalds flags, (void *)data_page); 12271da177e4SLinus Torvalds unlock_kernel(); 12281da177e4SLinus Torvalds free_page(data_page); 12291da177e4SLinus Torvalds 12301da177e4SLinus Torvalds out3: 12311da177e4SLinus Torvalds free_page(dev_page); 12321da177e4SLinus Torvalds out2: 12331da177e4SLinus Torvalds putname(dir_page); 12341da177e4SLinus Torvalds out1: 12351da177e4SLinus Torvalds free_page(type_page); 12361da177e4SLinus Torvalds return retval; 12371da177e4SLinus Torvalds } 12381da177e4SLinus Torvalds 12391da177e4SLinus Torvalds /* 12401da177e4SLinus Torvalds * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. 12411da177e4SLinus Torvalds * It can block. Requires the big lock held. 12421da177e4SLinus Torvalds */ 12431da177e4SLinus Torvalds void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, 12441da177e4SLinus Torvalds struct dentry *dentry) 12451da177e4SLinus Torvalds { 12461da177e4SLinus Torvalds struct dentry *old_root; 12471da177e4SLinus Torvalds struct vfsmount *old_rootmnt; 12481da177e4SLinus Torvalds write_lock(&fs->lock); 12491da177e4SLinus Torvalds old_root = fs->root; 12501da177e4SLinus Torvalds old_rootmnt = fs->rootmnt; 12511da177e4SLinus Torvalds fs->rootmnt = mntget(mnt); 12521da177e4SLinus Torvalds fs->root = dget(dentry); 12531da177e4SLinus Torvalds write_unlock(&fs->lock); 12541da177e4SLinus Torvalds if (old_root) { 12551da177e4SLinus Torvalds dput(old_root); 12561da177e4SLinus Torvalds mntput(old_rootmnt); 12571da177e4SLinus Torvalds } 12581da177e4SLinus Torvalds } 12591da177e4SLinus Torvalds 12601da177e4SLinus Torvalds /* 12611da177e4SLinus Torvalds * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. 12621da177e4SLinus Torvalds * It can block. Requires the big lock held. 12631da177e4SLinus Torvalds */ 12641da177e4SLinus Torvalds void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, 12651da177e4SLinus Torvalds struct dentry *dentry) 12661da177e4SLinus Torvalds { 12671da177e4SLinus Torvalds struct dentry *old_pwd; 12681da177e4SLinus Torvalds struct vfsmount *old_pwdmnt; 12691da177e4SLinus Torvalds 12701da177e4SLinus Torvalds write_lock(&fs->lock); 12711da177e4SLinus Torvalds old_pwd = fs->pwd; 12721da177e4SLinus Torvalds old_pwdmnt = fs->pwdmnt; 12731da177e4SLinus Torvalds fs->pwdmnt = mntget(mnt); 12741da177e4SLinus Torvalds fs->pwd = dget(dentry); 12751da177e4SLinus Torvalds write_unlock(&fs->lock); 12761da177e4SLinus Torvalds 12771da177e4SLinus Torvalds if (old_pwd) { 12781da177e4SLinus Torvalds dput(old_pwd); 12791da177e4SLinus Torvalds mntput(old_pwdmnt); 12801da177e4SLinus Torvalds } 12811da177e4SLinus Torvalds } 12821da177e4SLinus Torvalds 12831da177e4SLinus Torvalds static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) 12841da177e4SLinus Torvalds { 12851da177e4SLinus Torvalds struct task_struct *g, *p; 12861da177e4SLinus Torvalds struct fs_struct *fs; 12871da177e4SLinus Torvalds 12881da177e4SLinus Torvalds read_lock(&tasklist_lock); 12891da177e4SLinus Torvalds do_each_thread(g, p) { 12901da177e4SLinus Torvalds task_lock(p); 12911da177e4SLinus Torvalds fs = p->fs; 12921da177e4SLinus Torvalds if (fs) { 12931da177e4SLinus Torvalds atomic_inc(&fs->count); 12941da177e4SLinus Torvalds task_unlock(p); 1295b58fed8bSRam Pai if (fs->root == old_nd->dentry 1296b58fed8bSRam Pai && fs->rootmnt == old_nd->mnt) 12971da177e4SLinus Torvalds set_fs_root(fs, new_nd->mnt, new_nd->dentry); 1298b58fed8bSRam Pai if (fs->pwd == old_nd->dentry 1299b58fed8bSRam Pai && fs->pwdmnt == old_nd->mnt) 13001da177e4SLinus Torvalds set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); 13011da177e4SLinus Torvalds put_fs_struct(fs); 13021da177e4SLinus Torvalds } else 13031da177e4SLinus Torvalds task_unlock(p); 13041da177e4SLinus Torvalds } while_each_thread(g, p); 13051da177e4SLinus Torvalds read_unlock(&tasklist_lock); 13061da177e4SLinus Torvalds } 13071da177e4SLinus Torvalds 13081da177e4SLinus Torvalds /* 13091da177e4SLinus Torvalds * pivot_root Semantics: 13101da177e4SLinus Torvalds * Moves the root file system of the current process to the directory put_old, 13111da177e4SLinus Torvalds * makes new_root as the new root file system of the current process, and sets 13121da177e4SLinus Torvalds * root/cwd of all processes which had them on the current root to new_root. 13131da177e4SLinus Torvalds * 13141da177e4SLinus Torvalds * Restrictions: 13151da177e4SLinus Torvalds * The new_root and put_old must be directories, and must not be on the 13161da177e4SLinus Torvalds * same file system as the current process root. The put_old must be 13171da177e4SLinus Torvalds * underneath new_root, i.e. adding a non-zero number of /.. to the string 13181da177e4SLinus Torvalds * pointed to by put_old must yield the same directory as new_root. No other 13191da177e4SLinus Torvalds * file system may be mounted on put_old. After all, new_root is a mountpoint. 13201da177e4SLinus Torvalds * 13211da177e4SLinus Torvalds * Notes: 13221da177e4SLinus Torvalds * - we don't move root/cwd if they are not at the root (reason: if something 13231da177e4SLinus Torvalds * cared enough to change them, it's probably wrong to force them elsewhere) 13241da177e4SLinus Torvalds * - it's okay to pick a root that isn't the root of a file system, e.g. 13251da177e4SLinus Torvalds * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, 13261da177e4SLinus Torvalds * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root 13271da177e4SLinus Torvalds * first. 13281da177e4SLinus Torvalds */ 1329b58fed8bSRam Pai asmlinkage long sys_pivot_root(const char __user * new_root, 1330b58fed8bSRam Pai const char __user * put_old) 13311da177e4SLinus Torvalds { 13321da177e4SLinus Torvalds struct vfsmount *tmp; 13331da177e4SLinus Torvalds struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; 13341da177e4SLinus Torvalds int error; 13351da177e4SLinus Torvalds 13361da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 13371da177e4SLinus Torvalds return -EPERM; 13381da177e4SLinus Torvalds 13391da177e4SLinus Torvalds lock_kernel(); 13401da177e4SLinus Torvalds 1341b58fed8bSRam Pai error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, 1342b58fed8bSRam Pai &new_nd); 13431da177e4SLinus Torvalds if (error) 13441da177e4SLinus Torvalds goto out0; 13451da177e4SLinus Torvalds error = -EINVAL; 13461da177e4SLinus Torvalds if (!check_mnt(new_nd.mnt)) 13471da177e4SLinus Torvalds goto out1; 13481da177e4SLinus Torvalds 13491da177e4SLinus Torvalds error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd); 13501da177e4SLinus Torvalds if (error) 13511da177e4SLinus Torvalds goto out1; 13521da177e4SLinus Torvalds 13531da177e4SLinus Torvalds error = security_sb_pivotroot(&old_nd, &new_nd); 13541da177e4SLinus Torvalds if (error) { 13551da177e4SLinus Torvalds path_release(&old_nd); 13561da177e4SLinus Torvalds goto out1; 13571da177e4SLinus Torvalds } 13581da177e4SLinus Torvalds 13591da177e4SLinus Torvalds read_lock(¤t->fs->lock); 13601da177e4SLinus Torvalds user_nd.mnt = mntget(current->fs->rootmnt); 13611da177e4SLinus Torvalds user_nd.dentry = dget(current->fs->root); 13621da177e4SLinus Torvalds read_unlock(¤t->fs->lock); 13631da177e4SLinus Torvalds down_write(¤t->namespace->sem); 13641da177e4SLinus Torvalds down(&old_nd.dentry->d_inode->i_sem); 13651da177e4SLinus Torvalds error = -EINVAL; 13661da177e4SLinus Torvalds if (!check_mnt(user_nd.mnt)) 13671da177e4SLinus Torvalds goto out2; 13681da177e4SLinus Torvalds error = -ENOENT; 13691da177e4SLinus Torvalds if (IS_DEADDIR(new_nd.dentry->d_inode)) 13701da177e4SLinus Torvalds goto out2; 13711da177e4SLinus Torvalds if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) 13721da177e4SLinus Torvalds goto out2; 13731da177e4SLinus Torvalds if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) 13741da177e4SLinus Torvalds goto out2; 13751da177e4SLinus Torvalds error = -EBUSY; 13761da177e4SLinus Torvalds if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) 13771da177e4SLinus Torvalds goto out2; /* loop, on the same file system */ 13781da177e4SLinus Torvalds error = -EINVAL; 13791da177e4SLinus Torvalds if (user_nd.mnt->mnt_root != user_nd.dentry) 13801da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 13810bb6fcc1SMiklos Szeredi if (user_nd.mnt->mnt_parent == user_nd.mnt) 13820bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 13831da177e4SLinus Torvalds if (new_nd.mnt->mnt_root != new_nd.dentry) 13841da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 13850bb6fcc1SMiklos Szeredi if (new_nd.mnt->mnt_parent == new_nd.mnt) 13860bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 13871da177e4SLinus Torvalds tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ 13881da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 13891da177e4SLinus Torvalds if (tmp != new_nd.mnt) { 13901da177e4SLinus Torvalds for (;;) { 13911da177e4SLinus Torvalds if (tmp->mnt_parent == tmp) 13921da177e4SLinus Torvalds goto out3; /* already mounted on put_old */ 13931da177e4SLinus Torvalds if (tmp->mnt_parent == new_nd.mnt) 13941da177e4SLinus Torvalds break; 13951da177e4SLinus Torvalds tmp = tmp->mnt_parent; 13961da177e4SLinus Torvalds } 13971da177e4SLinus Torvalds if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) 13981da177e4SLinus Torvalds goto out3; 13991da177e4SLinus Torvalds } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) 14001da177e4SLinus Torvalds goto out3; 14011da177e4SLinus Torvalds detach_mnt(new_nd.mnt, &parent_nd); 14021da177e4SLinus Torvalds detach_mnt(user_nd.mnt, &root_parent); 14031da177e4SLinus Torvalds attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ 14041da177e4SLinus Torvalds attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ 14055addc5ddSAl Viro touch_namespace(current->namespace); 14061da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 14071da177e4SLinus Torvalds chroot_fs_refs(&user_nd, &new_nd); 14081da177e4SLinus Torvalds security_sb_post_pivotroot(&user_nd, &new_nd); 14091da177e4SLinus Torvalds error = 0; 14101da177e4SLinus Torvalds path_release(&root_parent); 14111da177e4SLinus Torvalds path_release(&parent_nd); 14121da177e4SLinus Torvalds out2: 14131da177e4SLinus Torvalds up(&old_nd.dentry->d_inode->i_sem); 14141da177e4SLinus Torvalds up_write(¤t->namespace->sem); 14151da177e4SLinus Torvalds path_release(&user_nd); 14161da177e4SLinus Torvalds path_release(&old_nd); 14171da177e4SLinus Torvalds out1: 14181da177e4SLinus Torvalds path_release(&new_nd); 14191da177e4SLinus Torvalds out0: 14201da177e4SLinus Torvalds unlock_kernel(); 14211da177e4SLinus Torvalds return error; 14221da177e4SLinus Torvalds out3: 14231da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 14241da177e4SLinus Torvalds goto out2; 14251da177e4SLinus Torvalds } 14261da177e4SLinus Torvalds 14271da177e4SLinus Torvalds static void __init init_mount_tree(void) 14281da177e4SLinus Torvalds { 14291da177e4SLinus Torvalds struct vfsmount *mnt; 14301da177e4SLinus Torvalds struct namespace *namespace; 14311da177e4SLinus Torvalds struct task_struct *g, *p; 14321da177e4SLinus Torvalds 14331da177e4SLinus Torvalds mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); 14341da177e4SLinus Torvalds if (IS_ERR(mnt)) 14351da177e4SLinus Torvalds panic("Can't create rootfs"); 14361da177e4SLinus Torvalds namespace = kmalloc(sizeof(*namespace), GFP_KERNEL); 14371da177e4SLinus Torvalds if (!namespace) 14381da177e4SLinus Torvalds panic("Can't allocate initial namespace"); 14391da177e4SLinus Torvalds atomic_set(&namespace->count, 1); 14401da177e4SLinus Torvalds INIT_LIST_HEAD(&namespace->list); 14411da177e4SLinus Torvalds init_rwsem(&namespace->sem); 14425addc5ddSAl Viro init_waitqueue_head(&namespace->poll); 14435addc5ddSAl Viro namespace->event = 0; 14441da177e4SLinus Torvalds list_add(&mnt->mnt_list, &namespace->list); 14451da177e4SLinus Torvalds namespace->root = mnt; 14461da177e4SLinus Torvalds mnt->mnt_namespace = namespace; 14471da177e4SLinus Torvalds 14481da177e4SLinus Torvalds init_task.namespace = namespace; 14491da177e4SLinus Torvalds read_lock(&tasklist_lock); 14501da177e4SLinus Torvalds do_each_thread(g, p) { 14511da177e4SLinus Torvalds get_namespace(namespace); 14521da177e4SLinus Torvalds p->namespace = namespace; 14531da177e4SLinus Torvalds } while_each_thread(g, p); 14541da177e4SLinus Torvalds read_unlock(&tasklist_lock); 14551da177e4SLinus Torvalds 14561da177e4SLinus Torvalds set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root); 14571da177e4SLinus Torvalds set_fs_root(current->fs, namespace->root, namespace->root->mnt_root); 14581da177e4SLinus Torvalds } 14591da177e4SLinus Torvalds 14601da177e4SLinus Torvalds void __init mnt_init(unsigned long mempages) 14611da177e4SLinus Torvalds { 14621da177e4SLinus Torvalds struct list_head *d; 14631da177e4SLinus Torvalds unsigned int nr_hash; 14641da177e4SLinus Torvalds int i; 14651da177e4SLinus Torvalds 14661da177e4SLinus Torvalds mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), 14671da177e4SLinus Torvalds 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL, NULL); 14681da177e4SLinus Torvalds 1469b58fed8bSRam Pai mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); 14701da177e4SLinus Torvalds 14711da177e4SLinus Torvalds if (!mount_hashtable) 14721da177e4SLinus Torvalds panic("Failed to allocate mount hash table\n"); 14731da177e4SLinus Torvalds 14741da177e4SLinus Torvalds /* 14751da177e4SLinus Torvalds * Find the power-of-two list-heads that can fit into the allocation.. 14761da177e4SLinus Torvalds * We don't guarantee that "sizeof(struct list_head)" is necessarily 14771da177e4SLinus Torvalds * a power-of-two. 14781da177e4SLinus Torvalds */ 14791da177e4SLinus Torvalds nr_hash = PAGE_SIZE / sizeof(struct list_head); 14801da177e4SLinus Torvalds hash_bits = 0; 14811da177e4SLinus Torvalds do { 14821da177e4SLinus Torvalds hash_bits++; 14831da177e4SLinus Torvalds } while ((nr_hash >> hash_bits) != 0); 14841da177e4SLinus Torvalds hash_bits--; 14851da177e4SLinus Torvalds 14861da177e4SLinus Torvalds /* 14871da177e4SLinus Torvalds * Re-calculate the actual number of entries and the mask 14881da177e4SLinus Torvalds * from the number of bits we can fit. 14891da177e4SLinus Torvalds */ 14901da177e4SLinus Torvalds nr_hash = 1UL << hash_bits; 14911da177e4SLinus Torvalds hash_mask = nr_hash - 1; 14921da177e4SLinus Torvalds 14931da177e4SLinus Torvalds printk("Mount-cache hash table entries: %d\n", nr_hash); 14941da177e4SLinus Torvalds 14951da177e4SLinus Torvalds /* And initialize the newly allocated array */ 14961da177e4SLinus Torvalds d = mount_hashtable; 14971da177e4SLinus Torvalds i = nr_hash; 14981da177e4SLinus Torvalds do { 14991da177e4SLinus Torvalds INIT_LIST_HEAD(d); 15001da177e4SLinus Torvalds d++; 15011da177e4SLinus Torvalds i--; 15021da177e4SLinus Torvalds } while (i); 15031da177e4SLinus Torvalds sysfs_init(); 15041da177e4SLinus Torvalds init_rootfs(); 15051da177e4SLinus Torvalds init_mount_tree(); 15061da177e4SLinus Torvalds } 15071da177e4SLinus Torvalds 15081da177e4SLinus Torvalds void __put_namespace(struct namespace *namespace) 15091da177e4SLinus Torvalds { 15101ce88cf4SMiklos Szeredi struct vfsmount *root = namespace->root; 15111ce88cf4SMiklos Szeredi namespace->root = NULL; 15121ce88cf4SMiklos Szeredi spin_unlock(&vfsmount_lock); 15131da177e4SLinus Torvalds down_write(&namespace->sem); 15141da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 15151ce88cf4SMiklos Szeredi umount_tree(root); 15161da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 15171da177e4SLinus Torvalds up_write(&namespace->sem); 15181da177e4SLinus Torvalds kfree(namespace); 15191da177e4SLinus Torvalds } 1520