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> 2707b20889SRam Pai #include "pnode.h" 281da177e4SLinus Torvalds 291da177e4SLinus Torvalds extern int __init init_rootfs(void); 301da177e4SLinus Torvalds 311da177e4SLinus Torvalds #ifdef CONFIG_SYSFS 321da177e4SLinus Torvalds extern int __init sysfs_init(void); 331da177e4SLinus Torvalds #else 341da177e4SLinus Torvalds static inline int sysfs_init(void) 351da177e4SLinus Torvalds { 361da177e4SLinus Torvalds return 0; 371da177e4SLinus Torvalds } 381da177e4SLinus Torvalds #endif 391da177e4SLinus Torvalds 401da177e4SLinus Torvalds /* spinlock for vfsmount related operations, inplace of dcache_lock */ 411da177e4SLinus Torvalds __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); 421da177e4SLinus Torvalds 435addc5ddSAl Viro static int event; 445addc5ddSAl Viro 451da177e4SLinus Torvalds static struct list_head *mount_hashtable; 466c231b7bSRavikiran G Thirumalai static int hash_mask __read_mostly, hash_bits __read_mostly; 471da177e4SLinus Torvalds static kmem_cache_t *mnt_cache; 48390c6843SRam Pai static struct rw_semaphore namespace_sem; 491da177e4SLinus Torvalds 501da177e4SLinus Torvalds static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) 511da177e4SLinus Torvalds { 521da177e4SLinus Torvalds unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); 531da177e4SLinus Torvalds tmp += ((unsigned long)dentry / L1_CACHE_BYTES); 541da177e4SLinus Torvalds tmp = tmp + (tmp >> hash_bits); 551da177e4SLinus Torvalds return tmp & hash_mask; 561da177e4SLinus Torvalds } 571da177e4SLinus Torvalds 581da177e4SLinus Torvalds struct vfsmount *alloc_vfsmnt(const char *name) 591da177e4SLinus Torvalds { 601da177e4SLinus Torvalds struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL); 611da177e4SLinus Torvalds if (mnt) { 621da177e4SLinus Torvalds memset(mnt, 0, sizeof(struct vfsmount)); 631da177e4SLinus Torvalds atomic_set(&mnt->mnt_count, 1); 641da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_hash); 651da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_child); 661da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_mounts); 671da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_list); 6855e700b9SMiklos Szeredi INIT_LIST_HEAD(&mnt->mnt_expire); 6903e06e68SRam Pai INIT_LIST_HEAD(&mnt->mnt_share); 70a58b0eb8SRam Pai INIT_LIST_HEAD(&mnt->mnt_slave_list); 71a58b0eb8SRam Pai INIT_LIST_HEAD(&mnt->mnt_slave); 721da177e4SLinus Torvalds if (name) { 731da177e4SLinus Torvalds int size = strlen(name) + 1; 741da177e4SLinus Torvalds char *newname = kmalloc(size, GFP_KERNEL); 751da177e4SLinus Torvalds if (newname) { 761da177e4SLinus Torvalds memcpy(newname, name, size); 771da177e4SLinus Torvalds mnt->mnt_devname = newname; 781da177e4SLinus Torvalds } 791da177e4SLinus Torvalds } 801da177e4SLinus Torvalds } 811da177e4SLinus Torvalds return mnt; 821da177e4SLinus Torvalds } 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds void free_vfsmnt(struct vfsmount *mnt) 851da177e4SLinus Torvalds { 861da177e4SLinus Torvalds kfree(mnt->mnt_devname); 871da177e4SLinus Torvalds kmem_cache_free(mnt_cache, mnt); 881da177e4SLinus Torvalds } 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* 91a05964f3SRam Pai * find the first or last mount at @dentry on vfsmount @mnt depending on 92a05964f3SRam Pai * @dir. If @dir is set return the first mount else return the last mount. 931da177e4SLinus Torvalds */ 94a05964f3SRam Pai struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, 95a05964f3SRam Pai int dir) 961da177e4SLinus Torvalds { 971da177e4SLinus Torvalds struct list_head *head = mount_hashtable + hash(mnt, dentry); 981da177e4SLinus Torvalds struct list_head *tmp = head; 991da177e4SLinus Torvalds struct vfsmount *p, *found = NULL; 1001da177e4SLinus Torvalds 1011da177e4SLinus Torvalds for (;;) { 102a05964f3SRam Pai tmp = dir ? tmp->next : tmp->prev; 1031da177e4SLinus Torvalds p = NULL; 1041da177e4SLinus Torvalds if (tmp == head) 1051da177e4SLinus Torvalds break; 1061da177e4SLinus Torvalds p = list_entry(tmp, struct vfsmount, mnt_hash); 1071da177e4SLinus Torvalds if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { 108a05964f3SRam Pai found = p; 1091da177e4SLinus Torvalds break; 1101da177e4SLinus Torvalds } 1111da177e4SLinus Torvalds } 1121da177e4SLinus Torvalds return found; 1131da177e4SLinus Torvalds } 1141da177e4SLinus Torvalds 115a05964f3SRam Pai /* 116a05964f3SRam Pai * lookup_mnt increments the ref count before returning 117a05964f3SRam Pai * the vfsmount struct. 118a05964f3SRam Pai */ 119a05964f3SRam Pai struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) 120a05964f3SRam Pai { 121a05964f3SRam Pai struct vfsmount *child_mnt; 122a05964f3SRam Pai spin_lock(&vfsmount_lock); 123a05964f3SRam Pai if ((child_mnt = __lookup_mnt(mnt, dentry, 1))) 124a05964f3SRam Pai mntget(child_mnt); 125a05964f3SRam Pai spin_unlock(&vfsmount_lock); 126a05964f3SRam Pai return child_mnt; 127a05964f3SRam Pai } 128a05964f3SRam Pai 1291da177e4SLinus Torvalds static inline int check_mnt(struct vfsmount *mnt) 1301da177e4SLinus Torvalds { 1311da177e4SLinus Torvalds return mnt->mnt_namespace == current->namespace; 1321da177e4SLinus Torvalds } 1331da177e4SLinus Torvalds 1345addc5ddSAl Viro static void touch_namespace(struct namespace *ns) 1355addc5ddSAl Viro { 1365addc5ddSAl Viro if (ns) { 1375addc5ddSAl Viro ns->event = ++event; 1385addc5ddSAl Viro wake_up_interruptible(&ns->poll); 1395addc5ddSAl Viro } 1405addc5ddSAl Viro } 1415addc5ddSAl Viro 1425addc5ddSAl Viro static void __touch_namespace(struct namespace *ns) 1435addc5ddSAl Viro { 1445addc5ddSAl Viro if (ns && ns->event != event) { 1455addc5ddSAl Viro ns->event = event; 1465addc5ddSAl Viro wake_up_interruptible(&ns->poll); 1475addc5ddSAl Viro } 1485addc5ddSAl Viro } 1495addc5ddSAl Viro 1501da177e4SLinus Torvalds static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) 1511da177e4SLinus Torvalds { 1521da177e4SLinus Torvalds old_nd->dentry = mnt->mnt_mountpoint; 1531da177e4SLinus Torvalds old_nd->mnt = mnt->mnt_parent; 1541da177e4SLinus Torvalds mnt->mnt_parent = mnt; 1551da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 1561da177e4SLinus Torvalds list_del_init(&mnt->mnt_child); 1571da177e4SLinus Torvalds list_del_init(&mnt->mnt_hash); 1581da177e4SLinus Torvalds old_nd->dentry->d_mounted--; 1591da177e4SLinus Torvalds } 1601da177e4SLinus Torvalds 161b90fa9aeSRam Pai void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, 162b90fa9aeSRam Pai struct vfsmount *child_mnt) 163b90fa9aeSRam Pai { 164b90fa9aeSRam Pai child_mnt->mnt_parent = mntget(mnt); 165b90fa9aeSRam Pai child_mnt->mnt_mountpoint = dget(dentry); 166b90fa9aeSRam Pai dentry->d_mounted++; 167b90fa9aeSRam Pai } 168b90fa9aeSRam Pai 1691da177e4SLinus Torvalds static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) 1701da177e4SLinus Torvalds { 171b90fa9aeSRam Pai mnt_set_mountpoint(nd->mnt, nd->dentry, mnt); 172b90fa9aeSRam Pai list_add_tail(&mnt->mnt_hash, mount_hashtable + 173b90fa9aeSRam Pai hash(nd->mnt, nd->dentry)); 1741da177e4SLinus Torvalds list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); 175b90fa9aeSRam Pai } 176b90fa9aeSRam Pai 177b90fa9aeSRam Pai /* 178b90fa9aeSRam Pai * the caller must hold vfsmount_lock 179b90fa9aeSRam Pai */ 180b90fa9aeSRam Pai static void commit_tree(struct vfsmount *mnt) 181b90fa9aeSRam Pai { 182b90fa9aeSRam Pai struct vfsmount *parent = mnt->mnt_parent; 183b90fa9aeSRam Pai struct vfsmount *m; 184b90fa9aeSRam Pai LIST_HEAD(head); 185b90fa9aeSRam Pai struct namespace *n = parent->mnt_namespace; 186b90fa9aeSRam Pai 187b90fa9aeSRam Pai BUG_ON(parent == mnt); 188b90fa9aeSRam Pai 189b90fa9aeSRam Pai list_add_tail(&head, &mnt->mnt_list); 190b90fa9aeSRam Pai list_for_each_entry(m, &head, mnt_list) 191b90fa9aeSRam Pai m->mnt_namespace = n; 192b90fa9aeSRam Pai list_splice(&head, n->list.prev); 193b90fa9aeSRam Pai 194b90fa9aeSRam Pai list_add_tail(&mnt->mnt_hash, mount_hashtable + 195b90fa9aeSRam Pai hash(parent, mnt->mnt_mountpoint)); 196b90fa9aeSRam Pai list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); 197b90fa9aeSRam Pai touch_namespace(n); 1981da177e4SLinus Torvalds } 1991da177e4SLinus Torvalds 2001da177e4SLinus Torvalds static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) 2011da177e4SLinus Torvalds { 2021da177e4SLinus Torvalds struct list_head *next = p->mnt_mounts.next; 2031da177e4SLinus Torvalds if (next == &p->mnt_mounts) { 2041da177e4SLinus Torvalds while (1) { 2051da177e4SLinus Torvalds if (p == root) 2061da177e4SLinus Torvalds return NULL; 2071da177e4SLinus Torvalds next = p->mnt_child.next; 2081da177e4SLinus Torvalds if (next != &p->mnt_parent->mnt_mounts) 2091da177e4SLinus Torvalds break; 2101da177e4SLinus Torvalds p = p->mnt_parent; 2111da177e4SLinus Torvalds } 2121da177e4SLinus Torvalds } 2131da177e4SLinus Torvalds return list_entry(next, struct vfsmount, mnt_child); 2141da177e4SLinus Torvalds } 2151da177e4SLinus Torvalds 21636341f64SRam Pai static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, 21736341f64SRam Pai int flag) 2181da177e4SLinus Torvalds { 2191da177e4SLinus Torvalds struct super_block *sb = old->mnt_sb; 2201da177e4SLinus Torvalds struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); 2211da177e4SLinus Torvalds 2221da177e4SLinus Torvalds if (mnt) { 2231da177e4SLinus Torvalds mnt->mnt_flags = old->mnt_flags; 2241da177e4SLinus Torvalds atomic_inc(&sb->s_active); 2251da177e4SLinus Torvalds mnt->mnt_sb = sb; 2261da177e4SLinus Torvalds mnt->mnt_root = dget(root); 2271da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 2281da177e4SLinus Torvalds mnt->mnt_parent = mnt; 229b90fa9aeSRam Pai 2305afe0022SRam Pai if (flag & CL_SLAVE) { 2315afe0022SRam Pai list_add(&mnt->mnt_slave, &old->mnt_slave_list); 2325afe0022SRam Pai mnt->mnt_master = old; 2335afe0022SRam Pai CLEAR_MNT_SHARED(mnt); 2345afe0022SRam Pai } else { 235b90fa9aeSRam Pai if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) 236b90fa9aeSRam Pai list_add(&mnt->mnt_share, &old->mnt_share); 2375afe0022SRam Pai if (IS_MNT_SLAVE(old)) 2385afe0022SRam Pai list_add(&mnt->mnt_slave, &old->mnt_slave); 2395afe0022SRam Pai mnt->mnt_master = old->mnt_master; 2405afe0022SRam Pai } 241b90fa9aeSRam Pai if (flag & CL_MAKE_SHARED) 242b90fa9aeSRam Pai set_mnt_shared(mnt); 2431da177e4SLinus Torvalds 2441da177e4SLinus Torvalds /* stick the duplicate mount on the same expiry list 2451da177e4SLinus Torvalds * as the original if that was on one */ 24636341f64SRam Pai if (flag & CL_EXPIRE) { 2471da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 24855e700b9SMiklos Szeredi if (!list_empty(&old->mnt_expire)) 24955e700b9SMiklos Szeredi list_add(&mnt->mnt_expire, &old->mnt_expire); 2501da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 2511da177e4SLinus Torvalds } 25236341f64SRam Pai } 2531da177e4SLinus Torvalds return mnt; 2541da177e4SLinus Torvalds } 2551da177e4SLinus Torvalds 2567b7b1aceSAl Viro static inline void __mntput(struct vfsmount *mnt) 2571da177e4SLinus Torvalds { 2581da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 2591da177e4SLinus Torvalds dput(mnt->mnt_root); 2601da177e4SLinus Torvalds free_vfsmnt(mnt); 2611da177e4SLinus Torvalds deactivate_super(sb); 2621da177e4SLinus Torvalds } 2631da177e4SLinus Torvalds 2647b7b1aceSAl Viro void mntput_no_expire(struct vfsmount *mnt) 2657b7b1aceSAl Viro { 2667b7b1aceSAl Viro repeat: 2677b7b1aceSAl Viro if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { 2687b7b1aceSAl Viro if (likely(!mnt->mnt_pinned)) { 2697b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2707b7b1aceSAl Viro __mntput(mnt); 2717b7b1aceSAl Viro return; 2727b7b1aceSAl Viro } 2737b7b1aceSAl Viro atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); 2747b7b1aceSAl Viro mnt->mnt_pinned = 0; 2757b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2767b7b1aceSAl Viro acct_auto_close_mnt(mnt); 2777b7b1aceSAl Viro security_sb_umount_close(mnt); 2787b7b1aceSAl Viro goto repeat; 2797b7b1aceSAl Viro } 2807b7b1aceSAl Viro } 2817b7b1aceSAl Viro 2827b7b1aceSAl Viro EXPORT_SYMBOL(mntput_no_expire); 2837b7b1aceSAl Viro 2847b7b1aceSAl Viro void mnt_pin(struct vfsmount *mnt) 2857b7b1aceSAl Viro { 2867b7b1aceSAl Viro spin_lock(&vfsmount_lock); 2877b7b1aceSAl Viro mnt->mnt_pinned++; 2887b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2897b7b1aceSAl Viro } 2907b7b1aceSAl Viro 2917b7b1aceSAl Viro EXPORT_SYMBOL(mnt_pin); 2927b7b1aceSAl Viro 2937b7b1aceSAl Viro void mnt_unpin(struct vfsmount *mnt) 2947b7b1aceSAl Viro { 2957b7b1aceSAl Viro spin_lock(&vfsmount_lock); 2967b7b1aceSAl Viro if (mnt->mnt_pinned) { 2977b7b1aceSAl Viro atomic_inc(&mnt->mnt_count); 2987b7b1aceSAl Viro mnt->mnt_pinned--; 2997b7b1aceSAl Viro } 3007b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 3017b7b1aceSAl Viro } 3027b7b1aceSAl Viro 3037b7b1aceSAl Viro EXPORT_SYMBOL(mnt_unpin); 3041da177e4SLinus Torvalds 3051da177e4SLinus Torvalds /* iterator */ 3061da177e4SLinus Torvalds static void *m_start(struct seq_file *m, loff_t *pos) 3071da177e4SLinus Torvalds { 3081da177e4SLinus Torvalds struct namespace *n = m->private; 3091da177e4SLinus Torvalds struct list_head *p; 3101da177e4SLinus Torvalds loff_t l = *pos; 3111da177e4SLinus Torvalds 312390c6843SRam Pai down_read(&namespace_sem); 3131da177e4SLinus Torvalds list_for_each(p, &n->list) 3141da177e4SLinus Torvalds if (!l--) 3151da177e4SLinus Torvalds return list_entry(p, struct vfsmount, mnt_list); 3161da177e4SLinus Torvalds return NULL; 3171da177e4SLinus Torvalds } 3181da177e4SLinus Torvalds 3191da177e4SLinus Torvalds static void *m_next(struct seq_file *m, void *v, loff_t *pos) 3201da177e4SLinus Torvalds { 3211da177e4SLinus Torvalds struct namespace *n = m->private; 3221da177e4SLinus Torvalds struct list_head *p = ((struct vfsmount *)v)->mnt_list.next; 3231da177e4SLinus Torvalds (*pos)++; 3241da177e4SLinus Torvalds return p == &n->list ? NULL : list_entry(p, struct vfsmount, mnt_list); 3251da177e4SLinus Torvalds } 3261da177e4SLinus Torvalds 3271da177e4SLinus Torvalds static void m_stop(struct seq_file *m, void *v) 3281da177e4SLinus Torvalds { 329390c6843SRam Pai up_read(&namespace_sem); 3301da177e4SLinus Torvalds } 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds static inline void mangle(struct seq_file *m, const char *s) 3331da177e4SLinus Torvalds { 3341da177e4SLinus Torvalds seq_escape(m, s, " \t\n\\"); 3351da177e4SLinus Torvalds } 3361da177e4SLinus Torvalds 3371da177e4SLinus Torvalds static int show_vfsmnt(struct seq_file *m, void *v) 3381da177e4SLinus Torvalds { 3391da177e4SLinus Torvalds struct vfsmount *mnt = v; 3401da177e4SLinus Torvalds int err = 0; 3411da177e4SLinus Torvalds static struct proc_fs_info { 3421da177e4SLinus Torvalds int flag; 3431da177e4SLinus Torvalds char *str; 3441da177e4SLinus Torvalds } fs_info[] = { 3451da177e4SLinus Torvalds { MS_SYNCHRONOUS, ",sync" }, 3461da177e4SLinus Torvalds { MS_DIRSYNC, ",dirsync" }, 3471da177e4SLinus Torvalds { MS_MANDLOCK, ",mand" }, 3481da177e4SLinus Torvalds { MS_NOATIME, ",noatime" }, 3491da177e4SLinus Torvalds { MS_NODIRATIME, ",nodiratime" }, 3501da177e4SLinus Torvalds { 0, NULL } 3511da177e4SLinus Torvalds }; 3521da177e4SLinus Torvalds static struct proc_fs_info mnt_info[] = { 3531da177e4SLinus Torvalds { MNT_NOSUID, ",nosuid" }, 3541da177e4SLinus Torvalds { MNT_NODEV, ",nodev" }, 3551da177e4SLinus Torvalds { MNT_NOEXEC, ",noexec" }, 3561da177e4SLinus Torvalds { 0, NULL } 3571da177e4SLinus Torvalds }; 3581da177e4SLinus Torvalds struct proc_fs_info *fs_infop; 3591da177e4SLinus Torvalds 3601da177e4SLinus Torvalds mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); 3611da177e4SLinus Torvalds seq_putc(m, ' '); 3621da177e4SLinus Torvalds seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); 3631da177e4SLinus Torvalds seq_putc(m, ' '); 3641da177e4SLinus Torvalds mangle(m, mnt->mnt_sb->s_type->name); 3651da177e4SLinus Torvalds seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); 3661da177e4SLinus Torvalds for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { 3671da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & fs_infop->flag) 3681da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 3691da177e4SLinus Torvalds } 3701da177e4SLinus Torvalds for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { 3711da177e4SLinus Torvalds if (mnt->mnt_flags & fs_infop->flag) 3721da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 3731da177e4SLinus Torvalds } 3741da177e4SLinus Torvalds if (mnt->mnt_sb->s_op->show_options) 3751da177e4SLinus Torvalds err = mnt->mnt_sb->s_op->show_options(m, mnt); 3761da177e4SLinus Torvalds seq_puts(m, " 0 0\n"); 3771da177e4SLinus Torvalds return err; 3781da177e4SLinus Torvalds } 3791da177e4SLinus Torvalds 3801da177e4SLinus Torvalds struct seq_operations mounts_op = { 3811da177e4SLinus Torvalds .start = m_start, 3821da177e4SLinus Torvalds .next = m_next, 3831da177e4SLinus Torvalds .stop = m_stop, 3841da177e4SLinus Torvalds .show = show_vfsmnt 3851da177e4SLinus Torvalds }; 3861da177e4SLinus Torvalds 3871da177e4SLinus Torvalds /** 3881da177e4SLinus Torvalds * may_umount_tree - check if a mount tree is busy 3891da177e4SLinus Torvalds * @mnt: root of mount tree 3901da177e4SLinus Torvalds * 3911da177e4SLinus Torvalds * This is called to check if a tree of mounts has any 3921da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts that are 3931da177e4SLinus Torvalds * busy. 3941da177e4SLinus Torvalds */ 3951da177e4SLinus Torvalds int may_umount_tree(struct vfsmount *mnt) 3961da177e4SLinus Torvalds { 39736341f64SRam Pai int actual_refs = 0; 39836341f64SRam Pai int minimum_refs = 0; 39936341f64SRam Pai struct vfsmount *p; 4001da177e4SLinus Torvalds 4011da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 40236341f64SRam Pai for (p = mnt; p; p = next_mnt(p, mnt)) { 4031da177e4SLinus Torvalds actual_refs += atomic_read(&p->mnt_count); 4041da177e4SLinus Torvalds minimum_refs += 2; 4051da177e4SLinus Torvalds } 4061da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 4071da177e4SLinus Torvalds 4081da177e4SLinus Torvalds if (actual_refs > minimum_refs) 4091da177e4SLinus Torvalds return -EBUSY; 4101da177e4SLinus Torvalds 4111da177e4SLinus Torvalds return 0; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4141da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount_tree); 4151da177e4SLinus Torvalds 4161da177e4SLinus Torvalds /** 4171da177e4SLinus Torvalds * may_umount - check if a mount point is busy 4181da177e4SLinus Torvalds * @mnt: root of mount 4191da177e4SLinus Torvalds * 4201da177e4SLinus Torvalds * This is called to check if a mount point has any 4211da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts. If the 4221da177e4SLinus Torvalds * mount has sub mounts this will return busy 4231da177e4SLinus Torvalds * regardless of whether the sub mounts are busy. 4241da177e4SLinus Torvalds * 4251da177e4SLinus Torvalds * Doesn't take quota and stuff into account. IOW, in some cases it will 4261da177e4SLinus Torvalds * give false negatives. The main reason why it's here is that we need 4271da177e4SLinus Torvalds * a non-destructive way to look for easily umountable filesystems. 4281da177e4SLinus Torvalds */ 4291da177e4SLinus Torvalds int may_umount(struct vfsmount *mnt) 4301da177e4SLinus Torvalds { 431a05964f3SRam Pai int ret = 0; 432a05964f3SRam Pai spin_lock(&vfsmount_lock); 433a05964f3SRam Pai if (propagate_mount_busy(mnt, 2)) 434a05964f3SRam Pai ret = -EBUSY; 435a05964f3SRam Pai spin_unlock(&vfsmount_lock); 436a05964f3SRam Pai return ret; 4371da177e4SLinus Torvalds } 4381da177e4SLinus Torvalds 4391da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount); 4401da177e4SLinus Torvalds 441b90fa9aeSRam Pai void release_mounts(struct list_head *head) 4421da177e4SLinus Torvalds { 44370fbcdf4SRam Pai struct vfsmount *mnt; 44470fbcdf4SRam Pai while(!list_empty(head)) { 44570fbcdf4SRam Pai mnt = list_entry(head->next, struct vfsmount, mnt_hash); 44670fbcdf4SRam Pai list_del_init(&mnt->mnt_hash); 44770fbcdf4SRam Pai if (mnt->mnt_parent != mnt) { 44870fbcdf4SRam Pai struct dentry *dentry; 44970fbcdf4SRam Pai struct vfsmount *m; 45070fbcdf4SRam Pai spin_lock(&vfsmount_lock); 45170fbcdf4SRam Pai dentry = mnt->mnt_mountpoint; 45270fbcdf4SRam Pai m = mnt->mnt_parent; 45370fbcdf4SRam Pai mnt->mnt_mountpoint = mnt->mnt_root; 45470fbcdf4SRam Pai mnt->mnt_parent = mnt; 4551da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 45670fbcdf4SRam Pai dput(dentry); 45770fbcdf4SRam Pai mntput(m); 4581da177e4SLinus Torvalds } 4591da177e4SLinus Torvalds mntput(mnt); 46070fbcdf4SRam Pai } 46170fbcdf4SRam Pai } 46270fbcdf4SRam Pai 463a05964f3SRam Pai void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) 46470fbcdf4SRam Pai { 46570fbcdf4SRam Pai struct vfsmount *p; 46670fbcdf4SRam Pai 46770fbcdf4SRam Pai for (p = mnt; p; p = next_mnt(p, mnt)) { 46870fbcdf4SRam Pai list_del(&p->mnt_hash); 46970fbcdf4SRam Pai list_add(&p->mnt_hash, kill); 47070fbcdf4SRam Pai } 47170fbcdf4SRam Pai 472a05964f3SRam Pai if (propagate) 473a05964f3SRam Pai propagate_umount(kill); 474a05964f3SRam Pai 47570fbcdf4SRam Pai list_for_each_entry(p, kill, mnt_hash) { 47670fbcdf4SRam Pai list_del_init(&p->mnt_expire); 47770fbcdf4SRam Pai list_del_init(&p->mnt_list); 47870fbcdf4SRam Pai __touch_namespace(p->mnt_namespace); 47970fbcdf4SRam Pai p->mnt_namespace = NULL; 48070fbcdf4SRam Pai list_del_init(&p->mnt_child); 48170fbcdf4SRam Pai if (p->mnt_parent != p) 48270fbcdf4SRam Pai mnt->mnt_mountpoint->d_mounted--; 483a05964f3SRam Pai change_mnt_propagation(p, MS_PRIVATE); 4841da177e4SLinus Torvalds } 4851da177e4SLinus Torvalds } 4861da177e4SLinus Torvalds 4871da177e4SLinus Torvalds static int do_umount(struct vfsmount *mnt, int flags) 4881da177e4SLinus Torvalds { 4891da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 4901da177e4SLinus Torvalds int retval; 49170fbcdf4SRam Pai LIST_HEAD(umount_list); 4921da177e4SLinus Torvalds 4931da177e4SLinus Torvalds retval = security_sb_umount(mnt, flags); 4941da177e4SLinus Torvalds if (retval) 4951da177e4SLinus Torvalds return retval; 4961da177e4SLinus Torvalds 4971da177e4SLinus Torvalds /* 4981da177e4SLinus Torvalds * Allow userspace to request a mountpoint be expired rather than 4991da177e4SLinus Torvalds * unmounting unconditionally. Unmount only happens if: 5001da177e4SLinus Torvalds * (1) the mark is already set (the mark is cleared by mntput()) 5011da177e4SLinus Torvalds * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] 5021da177e4SLinus Torvalds */ 5031da177e4SLinus Torvalds if (flags & MNT_EXPIRE) { 5041da177e4SLinus Torvalds if (mnt == current->fs->rootmnt || 5051da177e4SLinus Torvalds flags & (MNT_FORCE | MNT_DETACH)) 5061da177e4SLinus Torvalds return -EINVAL; 5071da177e4SLinus Torvalds 5081da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) != 2) 5091da177e4SLinus Torvalds return -EBUSY; 5101da177e4SLinus Torvalds 5111da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1)) 5121da177e4SLinus Torvalds return -EAGAIN; 5131da177e4SLinus Torvalds } 5141da177e4SLinus Torvalds 5151da177e4SLinus Torvalds /* 5161da177e4SLinus Torvalds * If we may have to abort operations to get out of this 5171da177e4SLinus Torvalds * mount, and they will themselves hold resources we must 5181da177e4SLinus Torvalds * allow the fs to do things. In the Unix tradition of 5191da177e4SLinus Torvalds * 'Gee thats tricky lets do it in userspace' the umount_begin 5201da177e4SLinus Torvalds * might fail to complete on the first run through as other tasks 5211da177e4SLinus Torvalds * must return, and the like. Thats for the mount program to worry 5221da177e4SLinus Torvalds * about for the moment. 5231da177e4SLinus Torvalds */ 5241da177e4SLinus Torvalds 5251da177e4SLinus Torvalds lock_kernel(); 5261da177e4SLinus Torvalds if ((flags & MNT_FORCE) && sb->s_op->umount_begin) 5271da177e4SLinus Torvalds sb->s_op->umount_begin(sb); 5281da177e4SLinus Torvalds unlock_kernel(); 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds /* 5311da177e4SLinus Torvalds * No sense to grab the lock for this test, but test itself looks 5321da177e4SLinus Torvalds * somewhat bogus. Suggestions for better replacement? 5331da177e4SLinus Torvalds * Ho-hum... In principle, we might treat that as umount + switch 5341da177e4SLinus Torvalds * to rootfs. GC would eventually take care of the old vfsmount. 5351da177e4SLinus Torvalds * Actually it makes sense, especially if rootfs would contain a 5361da177e4SLinus Torvalds * /reboot - static binary that would close all descriptors and 5371da177e4SLinus Torvalds * call reboot(9). Then init(8) could umount root and exec /reboot. 5381da177e4SLinus Torvalds */ 5391da177e4SLinus Torvalds if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { 5401da177e4SLinus Torvalds /* 5411da177e4SLinus Torvalds * Special case for "unmounting" root ... 5421da177e4SLinus Torvalds * we just try to remount it readonly. 5431da177e4SLinus Torvalds */ 5441da177e4SLinus Torvalds down_write(&sb->s_umount); 5451da177e4SLinus Torvalds if (!(sb->s_flags & MS_RDONLY)) { 5461da177e4SLinus Torvalds lock_kernel(); 5471da177e4SLinus Torvalds DQUOT_OFF(sb); 5481da177e4SLinus Torvalds retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); 5491da177e4SLinus Torvalds unlock_kernel(); 5501da177e4SLinus Torvalds } 5511da177e4SLinus Torvalds up_write(&sb->s_umount); 5521da177e4SLinus Torvalds return retval; 5531da177e4SLinus Torvalds } 5541da177e4SLinus Torvalds 555390c6843SRam Pai down_write(&namespace_sem); 5561da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 5575addc5ddSAl Viro event++; 5581da177e4SLinus Torvalds 5591da177e4SLinus Torvalds retval = -EBUSY; 560a05964f3SRam Pai if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { 5611da177e4SLinus Torvalds if (!list_empty(&mnt->mnt_list)) 562a05964f3SRam Pai umount_tree(mnt, 1, &umount_list); 5631da177e4SLinus Torvalds retval = 0; 5641da177e4SLinus Torvalds } 5651da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 5661da177e4SLinus Torvalds if (retval) 5671da177e4SLinus Torvalds security_sb_umount_busy(mnt); 568390c6843SRam Pai up_write(&namespace_sem); 56970fbcdf4SRam Pai release_mounts(&umount_list); 5701da177e4SLinus Torvalds return retval; 5711da177e4SLinus Torvalds } 5721da177e4SLinus Torvalds 5731da177e4SLinus Torvalds /* 5741da177e4SLinus Torvalds * Now umount can handle mount points as well as block devices. 5751da177e4SLinus Torvalds * This is important for filesystems which use unnamed block devices. 5761da177e4SLinus Torvalds * 5771da177e4SLinus Torvalds * We now support a flag for forced unmount like the other 'big iron' 5781da177e4SLinus Torvalds * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD 5791da177e4SLinus Torvalds */ 5801da177e4SLinus Torvalds 5811da177e4SLinus Torvalds asmlinkage long sys_umount(char __user * name, int flags) 5821da177e4SLinus Torvalds { 5831da177e4SLinus Torvalds struct nameidata nd; 5841da177e4SLinus Torvalds int retval; 5851da177e4SLinus Torvalds 5861da177e4SLinus Torvalds retval = __user_walk(name, LOOKUP_FOLLOW, &nd); 5871da177e4SLinus Torvalds if (retval) 5881da177e4SLinus Torvalds goto out; 5891da177e4SLinus Torvalds retval = -EINVAL; 5901da177e4SLinus Torvalds if (nd.dentry != nd.mnt->mnt_root) 5911da177e4SLinus Torvalds goto dput_and_out; 5921da177e4SLinus Torvalds if (!check_mnt(nd.mnt)) 5931da177e4SLinus Torvalds goto dput_and_out; 5941da177e4SLinus Torvalds 5951da177e4SLinus Torvalds retval = -EPERM; 5961da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 5971da177e4SLinus Torvalds goto dput_and_out; 5981da177e4SLinus Torvalds 5991da177e4SLinus Torvalds retval = do_umount(nd.mnt, flags); 6001da177e4SLinus Torvalds dput_and_out: 6011da177e4SLinus Torvalds path_release_on_umount(&nd); 6021da177e4SLinus Torvalds out: 6031da177e4SLinus Torvalds return retval; 6041da177e4SLinus Torvalds } 6051da177e4SLinus Torvalds 6061da177e4SLinus Torvalds #ifdef __ARCH_WANT_SYS_OLDUMOUNT 6071da177e4SLinus Torvalds 6081da177e4SLinus Torvalds /* 6091da177e4SLinus Torvalds * The 2.0 compatible umount. No flags. 6101da177e4SLinus Torvalds */ 6111da177e4SLinus Torvalds asmlinkage long sys_oldumount(char __user * name) 6121da177e4SLinus Torvalds { 6131da177e4SLinus Torvalds return sys_umount(name, 0); 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds 6161da177e4SLinus Torvalds #endif 6171da177e4SLinus Torvalds 6181da177e4SLinus Torvalds static int mount_is_safe(struct nameidata *nd) 6191da177e4SLinus Torvalds { 6201da177e4SLinus Torvalds if (capable(CAP_SYS_ADMIN)) 6211da177e4SLinus Torvalds return 0; 6221da177e4SLinus Torvalds return -EPERM; 6231da177e4SLinus Torvalds #ifdef notyet 6241da177e4SLinus Torvalds if (S_ISLNK(nd->dentry->d_inode->i_mode)) 6251da177e4SLinus Torvalds return -EPERM; 6261da177e4SLinus Torvalds if (nd->dentry->d_inode->i_mode & S_ISVTX) { 6271da177e4SLinus Torvalds if (current->uid != nd->dentry->d_inode->i_uid) 6281da177e4SLinus Torvalds return -EPERM; 6291da177e4SLinus Torvalds } 6301da177e4SLinus Torvalds if (permission(nd->dentry->d_inode, MAY_WRITE, nd)) 6311da177e4SLinus Torvalds return -EPERM; 6321da177e4SLinus Torvalds return 0; 6331da177e4SLinus Torvalds #endif 6341da177e4SLinus Torvalds } 6351da177e4SLinus Torvalds 636b58fed8bSRam Pai static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) 6371da177e4SLinus Torvalds { 6381da177e4SLinus Torvalds while (1) { 6391da177e4SLinus Torvalds if (d == dentry) 6401da177e4SLinus Torvalds return 1; 6411da177e4SLinus Torvalds if (d == NULL || d == d->d_parent) 6421da177e4SLinus Torvalds return 0; 6431da177e4SLinus Torvalds d = d->d_parent; 6441da177e4SLinus Torvalds } 6451da177e4SLinus Torvalds } 6461da177e4SLinus Torvalds 647b90fa9aeSRam Pai struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, 64836341f64SRam Pai int flag) 6491da177e4SLinus Torvalds { 6501da177e4SLinus Torvalds struct vfsmount *res, *p, *q, *r, *s; 6511da177e4SLinus Torvalds struct nameidata nd; 6521da177e4SLinus Torvalds 65336341f64SRam Pai res = q = clone_mnt(mnt, dentry, flag); 6541da177e4SLinus Torvalds if (!q) 6551da177e4SLinus Torvalds goto Enomem; 6561da177e4SLinus Torvalds q->mnt_mountpoint = mnt->mnt_mountpoint; 6571da177e4SLinus Torvalds 6581da177e4SLinus Torvalds p = mnt; 659fdadd65fSDomen Puncer list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { 6601da177e4SLinus Torvalds if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) 6611da177e4SLinus Torvalds continue; 6621da177e4SLinus Torvalds 6631da177e4SLinus Torvalds for (s = r; s; s = next_mnt(s, r)) { 6641da177e4SLinus Torvalds while (p != s->mnt_parent) { 6651da177e4SLinus Torvalds p = p->mnt_parent; 6661da177e4SLinus Torvalds q = q->mnt_parent; 6671da177e4SLinus Torvalds } 6681da177e4SLinus Torvalds p = s; 6691da177e4SLinus Torvalds nd.mnt = q; 6701da177e4SLinus Torvalds nd.dentry = p->mnt_mountpoint; 67136341f64SRam Pai q = clone_mnt(p, p->mnt_root, flag); 6721da177e4SLinus Torvalds if (!q) 6731da177e4SLinus Torvalds goto Enomem; 6741da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6751da177e4SLinus Torvalds list_add_tail(&q->mnt_list, &res->mnt_list); 6761da177e4SLinus Torvalds attach_mnt(q, &nd); 6771da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6781da177e4SLinus Torvalds } 6791da177e4SLinus Torvalds } 6801da177e4SLinus Torvalds return res; 6811da177e4SLinus Torvalds Enomem: 6821da177e4SLinus Torvalds if (res) { 68370fbcdf4SRam Pai LIST_HEAD(umount_list); 6841da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 685a05964f3SRam Pai umount_tree(res, 0, &umount_list); 6861da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 68770fbcdf4SRam Pai release_mounts(&umount_list); 6881da177e4SLinus Torvalds } 6891da177e4SLinus Torvalds return NULL; 6901da177e4SLinus Torvalds } 6911da177e4SLinus Torvalds 692b90fa9aeSRam Pai /* 693b90fa9aeSRam Pai * @source_mnt : mount tree to be attached 694b90fa9aeSRam Pai * @nd : place the mount tree @source_mnt is attached 69521444403SRam Pai * @parent_nd : if non-null, detach the source_mnt from its parent and 69621444403SRam Pai * store the parent mount and mountpoint dentry. 69721444403SRam Pai * (done when source_mnt is moved) 698b90fa9aeSRam Pai * 699b90fa9aeSRam Pai * NOTE: in the table below explains the semantics when a source mount 700b90fa9aeSRam Pai * of a given type is attached to a destination mount of a given type. 7015afe0022SRam Pai * ------------------------------------------------------------- 702b90fa9aeSRam Pai * | BIND MOUNT OPERATION | 7035afe0022SRam Pai * |************************************************************* 7045afe0022SRam Pai * | source-->| shared | private | slave | 7055afe0022SRam Pai * | dest | | | | 7065afe0022SRam Pai * | | | | | | 7075afe0022SRam Pai * | v | | | | 7085afe0022SRam Pai * |************************************************************* 7095afe0022SRam Pai * | shared | shared (++) | shared (+) | shared(+++)| 710b90fa9aeSRam Pai * | | | | | 7115afe0022SRam Pai * |non-shared| shared (+) | private | slave (*) | 7125afe0022SRam Pai * ************************************************************** 713b90fa9aeSRam Pai * A bind operation clones the source mount and mounts the clone on the 714b90fa9aeSRam Pai * destination mount. 715b90fa9aeSRam Pai * 716b90fa9aeSRam Pai * (++) the cloned mount is propagated to all the mounts in the propagation 717b90fa9aeSRam Pai * tree of the destination mount and the cloned mount is added to 718b90fa9aeSRam Pai * the peer group of the source mount. 719b90fa9aeSRam Pai * (+) the cloned mount is created under the destination mount and is marked 720b90fa9aeSRam Pai * as shared. The cloned mount is added to the peer group of the source 721b90fa9aeSRam Pai * mount. 7225afe0022SRam Pai * (+++) the mount is propagated to all the mounts in the propagation tree 7235afe0022SRam Pai * of the destination mount and the cloned mount is made slave 7245afe0022SRam Pai * of the same master as that of the source mount. The cloned mount 7255afe0022SRam Pai * is marked as 'shared and slave'. 7265afe0022SRam Pai * (*) the cloned mount is made a slave of the same master as that of the 7275afe0022SRam Pai * source mount. 7285afe0022SRam Pai * 7295afe0022SRam Pai * -------------------------------------------------------------- 73021444403SRam Pai * | MOVE MOUNT OPERATION | 7315afe0022SRam Pai * |************************************************************* 7325afe0022SRam Pai * | source-->| shared | private | slave | 7335afe0022SRam Pai * | dest | | | | 7345afe0022SRam Pai * | | | | | | 7355afe0022SRam Pai * | v | | | | 7365afe0022SRam Pai * |************************************************************* 7375afe0022SRam Pai * | shared | shared (+) | shared (+) | shared(+++) | 73821444403SRam Pai * | | | | | 7395afe0022SRam Pai * |non-shared| shared (+*) | private | slave (*) | 7405afe0022SRam Pai * ************************************************************** 7415afe0022SRam Pai * 7425afe0022SRam Pai * (+) the mount is moved to the destination. And is then propagated to 7435afe0022SRam Pai * all the mounts in the propagation tree of the destination mount. 74421444403SRam Pai * (+*) the mount is moved to the destination. 7455afe0022SRam Pai * (+++) the mount is moved to the destination and is then propagated to 7465afe0022SRam Pai * all the mounts belonging to the destination mount's propagation tree. 7475afe0022SRam Pai * the mount is marked as 'shared and slave'. 7485afe0022SRam Pai * (*) the mount continues to be a slave at the new location. 749b90fa9aeSRam Pai * 750b90fa9aeSRam Pai * if the source mount is a tree, the operations explained above is 751b90fa9aeSRam Pai * applied to each mount in the tree. 752b90fa9aeSRam Pai * Must be called without spinlocks held, since this function can sleep 753b90fa9aeSRam Pai * in allocations. 754b90fa9aeSRam Pai */ 755b90fa9aeSRam Pai static int attach_recursive_mnt(struct vfsmount *source_mnt, 75621444403SRam Pai struct nameidata *nd, struct nameidata *parent_nd) 757b90fa9aeSRam Pai { 758b90fa9aeSRam Pai LIST_HEAD(tree_list); 759b90fa9aeSRam Pai struct vfsmount *dest_mnt = nd->mnt; 760b90fa9aeSRam Pai struct dentry *dest_dentry = nd->dentry; 761b90fa9aeSRam Pai struct vfsmount *child, *p; 762b90fa9aeSRam Pai 763b90fa9aeSRam Pai if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) 764b90fa9aeSRam Pai return -EINVAL; 765b90fa9aeSRam Pai 766b90fa9aeSRam Pai if (IS_MNT_SHARED(dest_mnt)) { 767b90fa9aeSRam Pai for (p = source_mnt; p; p = next_mnt(p, source_mnt)) 768b90fa9aeSRam Pai set_mnt_shared(p); 769b90fa9aeSRam Pai } 770b90fa9aeSRam Pai 771b90fa9aeSRam Pai spin_lock(&vfsmount_lock); 77221444403SRam Pai if (parent_nd) { 77321444403SRam Pai detach_mnt(source_mnt, parent_nd); 77421444403SRam Pai attach_mnt(source_mnt, nd); 77521444403SRam Pai touch_namespace(current->namespace); 77621444403SRam Pai } else { 777b90fa9aeSRam Pai mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); 778b90fa9aeSRam Pai commit_tree(source_mnt); 77921444403SRam Pai } 780b90fa9aeSRam Pai 781b90fa9aeSRam Pai list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { 782b90fa9aeSRam Pai list_del_init(&child->mnt_hash); 783b90fa9aeSRam Pai commit_tree(child); 784b90fa9aeSRam Pai } 785b90fa9aeSRam Pai spin_unlock(&vfsmount_lock); 786b90fa9aeSRam Pai return 0; 787b90fa9aeSRam Pai } 788b90fa9aeSRam Pai 7891da177e4SLinus Torvalds static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) 7901da177e4SLinus Torvalds { 7911da177e4SLinus Torvalds int err; 7921da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & MS_NOUSER) 7931da177e4SLinus Torvalds return -EINVAL; 7941da177e4SLinus Torvalds 7951da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 7961da177e4SLinus Torvalds S_ISDIR(mnt->mnt_root->d_inode->i_mode)) 7971da177e4SLinus Torvalds return -ENOTDIR; 7981da177e4SLinus Torvalds 7991da177e4SLinus Torvalds err = -ENOENT; 8001da177e4SLinus Torvalds down(&nd->dentry->d_inode->i_sem); 8011da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 8021da177e4SLinus Torvalds goto out_unlock; 8031da177e4SLinus Torvalds 8041da177e4SLinus Torvalds err = security_sb_check_sb(mnt, nd); 8051da177e4SLinus Torvalds if (err) 8061da177e4SLinus Torvalds goto out_unlock; 8071da177e4SLinus Torvalds 8081da177e4SLinus Torvalds err = -ENOENT; 809b90fa9aeSRam Pai if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) 81021444403SRam Pai err = attach_recursive_mnt(mnt, nd, NULL); 8111da177e4SLinus Torvalds out_unlock: 8121da177e4SLinus Torvalds up(&nd->dentry->d_inode->i_sem); 8131da177e4SLinus Torvalds if (!err) 8141da177e4SLinus Torvalds security_sb_post_addmount(mnt, nd); 8151da177e4SLinus Torvalds return err; 8161da177e4SLinus Torvalds } 8171da177e4SLinus Torvalds 8181da177e4SLinus Torvalds /* 81907b20889SRam Pai * recursively change the type of the mountpoint. 82007b20889SRam Pai */ 82107b20889SRam Pai static int do_change_type(struct nameidata *nd, int flag) 82207b20889SRam Pai { 82307b20889SRam Pai struct vfsmount *m, *mnt = nd->mnt; 82407b20889SRam Pai int recurse = flag & MS_REC; 82507b20889SRam Pai int type = flag & ~MS_REC; 82607b20889SRam Pai 82707b20889SRam Pai if (nd->dentry != nd->mnt->mnt_root) 82807b20889SRam Pai return -EINVAL; 82907b20889SRam Pai 83007b20889SRam Pai down_write(&namespace_sem); 83107b20889SRam Pai spin_lock(&vfsmount_lock); 83207b20889SRam Pai for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) 83307b20889SRam Pai change_mnt_propagation(m, type); 83407b20889SRam Pai spin_unlock(&vfsmount_lock); 83507b20889SRam Pai up_write(&namespace_sem); 83607b20889SRam Pai return 0; 83707b20889SRam Pai } 83807b20889SRam Pai 83907b20889SRam Pai /* 8401da177e4SLinus Torvalds * do loopback mount. 8411da177e4SLinus Torvalds */ 8421da177e4SLinus Torvalds static int do_loopback(struct nameidata *nd, char *old_name, int recurse) 8431da177e4SLinus Torvalds { 8441da177e4SLinus Torvalds struct nameidata old_nd; 8451da177e4SLinus Torvalds struct vfsmount *mnt = NULL; 8461da177e4SLinus Torvalds int err = mount_is_safe(nd); 8471da177e4SLinus Torvalds if (err) 8481da177e4SLinus Torvalds return err; 8491da177e4SLinus Torvalds if (!old_name || !*old_name) 8501da177e4SLinus Torvalds return -EINVAL; 8511da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 8521da177e4SLinus Torvalds if (err) 8531da177e4SLinus Torvalds return err; 8541da177e4SLinus Torvalds 855390c6843SRam Pai down_write(&namespace_sem); 8561da177e4SLinus Torvalds err = -EINVAL; 857ccd48bc7SAl Viro if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) 858ccd48bc7SAl Viro goto out; 859ccd48bc7SAl Viro 8601da177e4SLinus Torvalds err = -ENOMEM; 8611da177e4SLinus Torvalds if (recurse) 86236341f64SRam Pai mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0); 8631da177e4SLinus Torvalds else 86436341f64SRam Pai mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0); 8651da177e4SLinus Torvalds 866ccd48bc7SAl Viro if (!mnt) 867ccd48bc7SAl Viro goto out; 868ccd48bc7SAl Viro 8691da177e4SLinus Torvalds err = graft_tree(mnt, nd); 8701da177e4SLinus Torvalds if (err) { 87170fbcdf4SRam Pai LIST_HEAD(umount_list); 8721da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 873a05964f3SRam Pai umount_tree(mnt, 0, &umount_list); 8741da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 87570fbcdf4SRam Pai release_mounts(&umount_list); 8765b83d2c5SRam Pai } 8771da177e4SLinus Torvalds 878ccd48bc7SAl Viro out: 879390c6843SRam Pai up_write(&namespace_sem); 8801da177e4SLinus Torvalds path_release(&old_nd); 8811da177e4SLinus Torvalds return err; 8821da177e4SLinus Torvalds } 8831da177e4SLinus Torvalds 8841da177e4SLinus Torvalds /* 8851da177e4SLinus Torvalds * change filesystem flags. dir should be a physical root of filesystem. 8861da177e4SLinus Torvalds * If you've mounted a non-root directory somewhere and want to do remount 8871da177e4SLinus Torvalds * on it - tough luck. 8881da177e4SLinus Torvalds */ 8891da177e4SLinus Torvalds static int do_remount(struct nameidata *nd, int flags, int mnt_flags, 8901da177e4SLinus Torvalds void *data) 8911da177e4SLinus Torvalds { 8921da177e4SLinus Torvalds int err; 8931da177e4SLinus Torvalds struct super_block *sb = nd->mnt->mnt_sb; 8941da177e4SLinus Torvalds 8951da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 8961da177e4SLinus Torvalds return -EPERM; 8971da177e4SLinus Torvalds 8981da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 8991da177e4SLinus Torvalds return -EINVAL; 9001da177e4SLinus Torvalds 9011da177e4SLinus Torvalds if (nd->dentry != nd->mnt->mnt_root) 9021da177e4SLinus Torvalds return -EINVAL; 9031da177e4SLinus Torvalds 9041da177e4SLinus Torvalds down_write(&sb->s_umount); 9051da177e4SLinus Torvalds err = do_remount_sb(sb, flags, data, 0); 9061da177e4SLinus Torvalds if (!err) 9071da177e4SLinus Torvalds nd->mnt->mnt_flags = mnt_flags; 9081da177e4SLinus Torvalds up_write(&sb->s_umount); 9091da177e4SLinus Torvalds if (!err) 9101da177e4SLinus Torvalds security_sb_post_remount(nd->mnt, flags, data); 9111da177e4SLinus Torvalds return err; 9121da177e4SLinus Torvalds } 9131da177e4SLinus Torvalds 9141da177e4SLinus Torvalds static int do_move_mount(struct nameidata *nd, char *old_name) 9151da177e4SLinus Torvalds { 9161da177e4SLinus Torvalds struct nameidata old_nd, parent_nd; 9171da177e4SLinus Torvalds struct vfsmount *p; 9181da177e4SLinus Torvalds int err = 0; 9191da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 9201da177e4SLinus Torvalds return -EPERM; 9211da177e4SLinus Torvalds if (!old_name || !*old_name) 9221da177e4SLinus Torvalds return -EINVAL; 9231da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 9241da177e4SLinus Torvalds if (err) 9251da177e4SLinus Torvalds return err; 9261da177e4SLinus Torvalds 927390c6843SRam Pai down_write(&namespace_sem); 9281da177e4SLinus Torvalds while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 9291da177e4SLinus Torvalds ; 9301da177e4SLinus Torvalds err = -EINVAL; 9311da177e4SLinus Torvalds if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) 9321da177e4SLinus Torvalds goto out; 9331da177e4SLinus Torvalds 9341da177e4SLinus Torvalds err = -ENOENT; 9351da177e4SLinus Torvalds down(&nd->dentry->d_inode->i_sem); 9361da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 9371da177e4SLinus Torvalds goto out1; 9381da177e4SLinus Torvalds 9391da177e4SLinus Torvalds if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) 94021444403SRam Pai goto out1; 9411da177e4SLinus Torvalds 9421da177e4SLinus Torvalds err = -EINVAL; 9431da177e4SLinus Torvalds if (old_nd.dentry != old_nd.mnt->mnt_root) 94421444403SRam Pai goto out1; 9451da177e4SLinus Torvalds 9461da177e4SLinus Torvalds if (old_nd.mnt == old_nd.mnt->mnt_parent) 94721444403SRam Pai goto out1; 9481da177e4SLinus Torvalds 9491da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 9501da177e4SLinus Torvalds S_ISDIR(old_nd.dentry->d_inode->i_mode)) 95121444403SRam Pai goto out1; 95221444403SRam Pai /* 95321444403SRam Pai * Don't move a mount residing in a shared parent. 95421444403SRam Pai */ 95521444403SRam Pai if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent)) 95621444403SRam Pai goto out1; 9571da177e4SLinus Torvalds err = -ELOOP; 9581da177e4SLinus Torvalds for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) 9591da177e4SLinus Torvalds if (p == old_nd.mnt) 96021444403SRam Pai goto out1; 9611da177e4SLinus Torvalds 96221444403SRam Pai if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd))) 96321444403SRam Pai goto out1; 9641da177e4SLinus Torvalds 96521444403SRam Pai spin_lock(&vfsmount_lock); 9661da177e4SLinus Torvalds /* if the mount is moved, it should no longer be expire 9671da177e4SLinus Torvalds * automatically */ 96855e700b9SMiklos Szeredi list_del_init(&old_nd.mnt->mnt_expire); 9691da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 9701da177e4SLinus Torvalds out1: 9711da177e4SLinus Torvalds up(&nd->dentry->d_inode->i_sem); 9721da177e4SLinus Torvalds out: 973390c6843SRam Pai up_write(&namespace_sem); 9741da177e4SLinus Torvalds if (!err) 9751da177e4SLinus Torvalds path_release(&parent_nd); 9761da177e4SLinus Torvalds path_release(&old_nd); 9771da177e4SLinus Torvalds return err; 9781da177e4SLinus Torvalds } 9791da177e4SLinus Torvalds 9801da177e4SLinus Torvalds /* 9811da177e4SLinus Torvalds * create a new mount for userspace and request it to be added into the 9821da177e4SLinus Torvalds * namespace's tree 9831da177e4SLinus Torvalds */ 9841da177e4SLinus Torvalds static int do_new_mount(struct nameidata *nd, char *type, int flags, 9851da177e4SLinus Torvalds int mnt_flags, char *name, void *data) 9861da177e4SLinus Torvalds { 9871da177e4SLinus Torvalds struct vfsmount *mnt; 9881da177e4SLinus Torvalds 9891da177e4SLinus Torvalds if (!type || !memchr(type, 0, PAGE_SIZE)) 9901da177e4SLinus Torvalds return -EINVAL; 9911da177e4SLinus Torvalds 9921da177e4SLinus Torvalds /* we need capabilities... */ 9931da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 9941da177e4SLinus Torvalds return -EPERM; 9951da177e4SLinus Torvalds 9961da177e4SLinus Torvalds mnt = do_kern_mount(type, flags, name, data); 9971da177e4SLinus Torvalds if (IS_ERR(mnt)) 9981da177e4SLinus Torvalds return PTR_ERR(mnt); 9991da177e4SLinus Torvalds 10001da177e4SLinus Torvalds return do_add_mount(mnt, nd, mnt_flags, NULL); 10011da177e4SLinus Torvalds } 10021da177e4SLinus Torvalds 10031da177e4SLinus Torvalds /* 10041da177e4SLinus Torvalds * add a mount into a namespace's mount tree 10051da177e4SLinus Torvalds * - provide the option of adding the new mount to an expiration list 10061da177e4SLinus Torvalds */ 10071da177e4SLinus Torvalds int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, 10081da177e4SLinus Torvalds int mnt_flags, struct list_head *fslist) 10091da177e4SLinus Torvalds { 10101da177e4SLinus Torvalds int err; 10111da177e4SLinus Torvalds 1012390c6843SRam Pai down_write(&namespace_sem); 10131da177e4SLinus Torvalds /* Something was mounted here while we slept */ 10141da177e4SLinus Torvalds while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 10151da177e4SLinus Torvalds ; 10161da177e4SLinus Torvalds err = -EINVAL; 10171da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 10181da177e4SLinus Torvalds goto unlock; 10191da177e4SLinus Torvalds 10201da177e4SLinus Torvalds /* Refuse the same filesystem on the same mount point */ 10211da177e4SLinus Torvalds err = -EBUSY; 10221da177e4SLinus Torvalds if (nd->mnt->mnt_sb == newmnt->mnt_sb && 10231da177e4SLinus Torvalds nd->mnt->mnt_root == nd->dentry) 10241da177e4SLinus Torvalds goto unlock; 10251da177e4SLinus Torvalds 10261da177e4SLinus Torvalds err = -EINVAL; 10271da177e4SLinus Torvalds if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) 10281da177e4SLinus Torvalds goto unlock; 10291da177e4SLinus Torvalds 10301da177e4SLinus Torvalds newmnt->mnt_flags = mnt_flags; 10315b83d2c5SRam Pai if ((err = graft_tree(newmnt, nd))) 10325b83d2c5SRam Pai goto unlock; 10331da177e4SLinus Torvalds 10345b83d2c5SRam Pai if (fslist) { 10351da177e4SLinus Torvalds /* add to the specified expiration list */ 10361da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 103755e700b9SMiklos Szeredi list_add_tail(&newmnt->mnt_expire, fslist); 10381da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 10391da177e4SLinus Torvalds } 1040390c6843SRam Pai up_write(&namespace_sem); 10415b83d2c5SRam Pai return 0; 10421da177e4SLinus Torvalds 10431da177e4SLinus Torvalds unlock: 1044390c6843SRam Pai up_write(&namespace_sem); 10451da177e4SLinus Torvalds mntput(newmnt); 10461da177e4SLinus Torvalds return err; 10471da177e4SLinus Torvalds } 10481da177e4SLinus Torvalds 10491da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(do_add_mount); 10501da177e4SLinus Torvalds 105170fbcdf4SRam Pai static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, 105270fbcdf4SRam Pai struct list_head *umounts) 105324ca2af1SMiklos Szeredi { 105424ca2af1SMiklos Szeredi spin_lock(&vfsmount_lock); 105524ca2af1SMiklos Szeredi 105624ca2af1SMiklos Szeredi /* 1057ed42c879SMiklos Szeredi * Check if mount is still attached, if not, let whoever holds it deal 1058ed42c879SMiklos Szeredi * with the sucker 1059ed42c879SMiklos Szeredi */ 1060ed42c879SMiklos Szeredi if (mnt->mnt_parent == mnt) { 1061ed42c879SMiklos Szeredi spin_unlock(&vfsmount_lock); 1062ed42c879SMiklos Szeredi return; 1063ed42c879SMiklos Szeredi } 1064ed42c879SMiklos Szeredi 1065ed42c879SMiklos Szeredi /* 106624ca2af1SMiklos Szeredi * Check that it is still dead: the count should now be 2 - as 106724ca2af1SMiklos Szeredi * contributed by the vfsmount parent and the mntget above 106824ca2af1SMiklos Szeredi */ 1069a05964f3SRam Pai if (!propagate_mount_busy(mnt, 2)) { 107024ca2af1SMiklos Szeredi /* delete from the namespace */ 10715addc5ddSAl Viro touch_namespace(mnt->mnt_namespace); 107224ca2af1SMiklos Szeredi list_del_init(&mnt->mnt_list); 1073ac081153SMiklos Szeredi mnt->mnt_namespace = NULL; 1074a05964f3SRam Pai umount_tree(mnt, 1, umounts); 107524ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 107624ca2af1SMiklos Szeredi } else { 107724ca2af1SMiklos Szeredi /* 107824ca2af1SMiklos Szeredi * Someone brought it back to life whilst we didn't have any 107924ca2af1SMiklos Szeredi * locks held so return it to the expiration list 108024ca2af1SMiklos Szeredi */ 108155e700b9SMiklos Szeredi list_add_tail(&mnt->mnt_expire, mounts); 108224ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 108324ca2af1SMiklos Szeredi } 108424ca2af1SMiklos Szeredi } 108524ca2af1SMiklos Szeredi 10861da177e4SLinus Torvalds /* 10871da177e4SLinus Torvalds * process a list of expirable mountpoints with the intent of discarding any 10881da177e4SLinus Torvalds * mountpoints that aren't in use and haven't been touched since last we came 10891da177e4SLinus Torvalds * here 10901da177e4SLinus Torvalds */ 10911da177e4SLinus Torvalds void mark_mounts_for_expiry(struct list_head *mounts) 10921da177e4SLinus Torvalds { 10931da177e4SLinus Torvalds struct namespace *namespace; 10941da177e4SLinus Torvalds struct vfsmount *mnt, *next; 10951da177e4SLinus Torvalds LIST_HEAD(graveyard); 10961da177e4SLinus Torvalds 10971da177e4SLinus Torvalds if (list_empty(mounts)) 10981da177e4SLinus Torvalds return; 10991da177e4SLinus Torvalds 11001da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 11011da177e4SLinus Torvalds 11021da177e4SLinus Torvalds /* extract from the expiration list every vfsmount that matches the 11031da177e4SLinus Torvalds * following criteria: 11041da177e4SLinus Torvalds * - only referenced by its parent vfsmount 11051da177e4SLinus Torvalds * - still marked for expiry (marked on the last call here; marks are 11061da177e4SLinus Torvalds * cleared by mntput()) 11071da177e4SLinus Torvalds */ 110855e700b9SMiklos Szeredi list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { 11091da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1) || 11101da177e4SLinus Torvalds atomic_read(&mnt->mnt_count) != 1) 11111da177e4SLinus Torvalds continue; 11121da177e4SLinus Torvalds 11131da177e4SLinus Torvalds mntget(mnt); 111455e700b9SMiklos Szeredi list_move(&mnt->mnt_expire, &graveyard); 11151da177e4SLinus Torvalds } 11161da177e4SLinus Torvalds 11171da177e4SLinus Torvalds /* 11181da177e4SLinus Torvalds * go through the vfsmounts we've just consigned to the graveyard to 11191da177e4SLinus Torvalds * - check that they're still dead 11201da177e4SLinus Torvalds * - delete the vfsmount from the appropriate namespace under lock 11211da177e4SLinus Torvalds * - dispose of the corpse 11221da177e4SLinus Torvalds */ 11231da177e4SLinus Torvalds while (!list_empty(&graveyard)) { 112470fbcdf4SRam Pai LIST_HEAD(umounts); 112555e700b9SMiklos Szeredi mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire); 112655e700b9SMiklos Szeredi list_del_init(&mnt->mnt_expire); 11271da177e4SLinus Torvalds 11281da177e4SLinus Torvalds /* don't do anything if the namespace is dead - all the 11291da177e4SLinus Torvalds * vfsmounts from it are going away anyway */ 11301da177e4SLinus Torvalds namespace = mnt->mnt_namespace; 11311ce88cf4SMiklos Szeredi if (!namespace || !namespace->root) 11321da177e4SLinus Torvalds continue; 11331da177e4SLinus Torvalds get_namespace(namespace); 11341da177e4SLinus Torvalds 11351da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1136390c6843SRam Pai down_write(&namespace_sem); 113770fbcdf4SRam Pai expire_mount(mnt, mounts, &umounts); 1138390c6843SRam Pai up_write(&namespace_sem); 113970fbcdf4SRam Pai release_mounts(&umounts); 11401da177e4SLinus Torvalds mntput(mnt); 11411da177e4SLinus Torvalds put_namespace(namespace); 11421da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 11431da177e4SLinus Torvalds } 11441da177e4SLinus Torvalds 11451da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 11461da177e4SLinus Torvalds } 11471da177e4SLinus Torvalds 11481da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); 11491da177e4SLinus Torvalds 11501da177e4SLinus Torvalds /* 11511da177e4SLinus Torvalds * Some copy_from_user() implementations do not return the exact number of 11521da177e4SLinus Torvalds * bytes remaining to copy on a fault. But copy_mount_options() requires that. 11531da177e4SLinus Torvalds * Note that this function differs from copy_from_user() in that it will oops 11541da177e4SLinus Torvalds * on bad values of `to', rather than returning a short copy. 11551da177e4SLinus Torvalds */ 1156b58fed8bSRam Pai static long exact_copy_from_user(void *to, const void __user * from, 1157b58fed8bSRam Pai unsigned long n) 11581da177e4SLinus Torvalds { 11591da177e4SLinus Torvalds char *t = to; 11601da177e4SLinus Torvalds const char __user *f = from; 11611da177e4SLinus Torvalds char c; 11621da177e4SLinus Torvalds 11631da177e4SLinus Torvalds if (!access_ok(VERIFY_READ, from, n)) 11641da177e4SLinus Torvalds return n; 11651da177e4SLinus Torvalds 11661da177e4SLinus Torvalds while (n) { 11671da177e4SLinus Torvalds if (__get_user(c, f)) { 11681da177e4SLinus Torvalds memset(t, 0, n); 11691da177e4SLinus Torvalds break; 11701da177e4SLinus Torvalds } 11711da177e4SLinus Torvalds *t++ = c; 11721da177e4SLinus Torvalds f++; 11731da177e4SLinus Torvalds n--; 11741da177e4SLinus Torvalds } 11751da177e4SLinus Torvalds return n; 11761da177e4SLinus Torvalds } 11771da177e4SLinus Torvalds 11781da177e4SLinus Torvalds int copy_mount_options(const void __user * data, unsigned long *where) 11791da177e4SLinus Torvalds { 11801da177e4SLinus Torvalds int i; 11811da177e4SLinus Torvalds unsigned long page; 11821da177e4SLinus Torvalds unsigned long size; 11831da177e4SLinus Torvalds 11841da177e4SLinus Torvalds *where = 0; 11851da177e4SLinus Torvalds if (!data) 11861da177e4SLinus Torvalds return 0; 11871da177e4SLinus Torvalds 11881da177e4SLinus Torvalds if (!(page = __get_free_page(GFP_KERNEL))) 11891da177e4SLinus Torvalds return -ENOMEM; 11901da177e4SLinus Torvalds 11911da177e4SLinus Torvalds /* We only care that *some* data at the address the user 11921da177e4SLinus Torvalds * gave us is valid. Just in case, we'll zero 11931da177e4SLinus Torvalds * the remainder of the page. 11941da177e4SLinus Torvalds */ 11951da177e4SLinus Torvalds /* copy_from_user cannot cross TASK_SIZE ! */ 11961da177e4SLinus Torvalds size = TASK_SIZE - (unsigned long)data; 11971da177e4SLinus Torvalds if (size > PAGE_SIZE) 11981da177e4SLinus Torvalds size = PAGE_SIZE; 11991da177e4SLinus Torvalds 12001da177e4SLinus Torvalds i = size - exact_copy_from_user((void *)page, data, size); 12011da177e4SLinus Torvalds if (!i) { 12021da177e4SLinus Torvalds free_page(page); 12031da177e4SLinus Torvalds return -EFAULT; 12041da177e4SLinus Torvalds } 12051da177e4SLinus Torvalds if (i != PAGE_SIZE) 12061da177e4SLinus Torvalds memset((char *)page + i, 0, PAGE_SIZE - i); 12071da177e4SLinus Torvalds *where = page; 12081da177e4SLinus Torvalds return 0; 12091da177e4SLinus Torvalds } 12101da177e4SLinus Torvalds 12111da177e4SLinus Torvalds /* 12121da177e4SLinus Torvalds * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to 12131da177e4SLinus Torvalds * be given to the mount() call (ie: read-only, no-dev, no-suid etc). 12141da177e4SLinus Torvalds * 12151da177e4SLinus Torvalds * data is a (void *) that can point to any structure up to 12161da177e4SLinus Torvalds * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent 12171da177e4SLinus Torvalds * information (or be NULL). 12181da177e4SLinus Torvalds * 12191da177e4SLinus Torvalds * Pre-0.97 versions of mount() didn't have a flags word. 12201da177e4SLinus Torvalds * When the flags word was introduced its top half was required 12211da177e4SLinus Torvalds * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. 12221da177e4SLinus Torvalds * Therefore, if this magic number is present, it carries no information 12231da177e4SLinus Torvalds * and must be discarded. 12241da177e4SLinus Torvalds */ 12251da177e4SLinus Torvalds long do_mount(char *dev_name, char *dir_name, char *type_page, 12261da177e4SLinus Torvalds unsigned long flags, void *data_page) 12271da177e4SLinus Torvalds { 12281da177e4SLinus Torvalds struct nameidata nd; 12291da177e4SLinus Torvalds int retval = 0; 12301da177e4SLinus Torvalds int mnt_flags = 0; 12311da177e4SLinus Torvalds 12321da177e4SLinus Torvalds /* Discard magic */ 12331da177e4SLinus Torvalds if ((flags & MS_MGC_MSK) == MS_MGC_VAL) 12341da177e4SLinus Torvalds flags &= ~MS_MGC_MSK; 12351da177e4SLinus Torvalds 12361da177e4SLinus Torvalds /* Basic sanity checks */ 12371da177e4SLinus Torvalds 12381da177e4SLinus Torvalds if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) 12391da177e4SLinus Torvalds return -EINVAL; 12401da177e4SLinus Torvalds if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) 12411da177e4SLinus Torvalds return -EINVAL; 12421da177e4SLinus Torvalds 12431da177e4SLinus Torvalds if (data_page) 12441da177e4SLinus Torvalds ((char *)data_page)[PAGE_SIZE - 1] = 0; 12451da177e4SLinus Torvalds 12461da177e4SLinus Torvalds /* Separate the per-mountpoint flags */ 12471da177e4SLinus Torvalds if (flags & MS_NOSUID) 12481da177e4SLinus Torvalds mnt_flags |= MNT_NOSUID; 12491da177e4SLinus Torvalds if (flags & MS_NODEV) 12501da177e4SLinus Torvalds mnt_flags |= MNT_NODEV; 12511da177e4SLinus Torvalds if (flags & MS_NOEXEC) 12521da177e4SLinus Torvalds mnt_flags |= MNT_NOEXEC; 12531da177e4SLinus Torvalds flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE); 12541da177e4SLinus Torvalds 12551da177e4SLinus Torvalds /* ... and get the mountpoint */ 12561da177e4SLinus Torvalds retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); 12571da177e4SLinus Torvalds if (retval) 12581da177e4SLinus Torvalds return retval; 12591da177e4SLinus Torvalds 12601da177e4SLinus Torvalds retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); 12611da177e4SLinus Torvalds if (retval) 12621da177e4SLinus Torvalds goto dput_out; 12631da177e4SLinus Torvalds 12641da177e4SLinus Torvalds if (flags & MS_REMOUNT) 12651da177e4SLinus Torvalds retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, 12661da177e4SLinus Torvalds data_page); 12671da177e4SLinus Torvalds else if (flags & MS_BIND) 12681da177e4SLinus Torvalds retval = do_loopback(&nd, dev_name, flags & MS_REC); 1269a58b0eb8SRam Pai else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE)) 127007b20889SRam Pai retval = do_change_type(&nd, flags); 12711da177e4SLinus Torvalds else if (flags & MS_MOVE) 12721da177e4SLinus Torvalds retval = do_move_mount(&nd, dev_name); 12731da177e4SLinus Torvalds else 12741da177e4SLinus Torvalds retval = do_new_mount(&nd, type_page, flags, mnt_flags, 12751da177e4SLinus Torvalds dev_name, data_page); 12761da177e4SLinus Torvalds dput_out: 12771da177e4SLinus Torvalds path_release(&nd); 12781da177e4SLinus Torvalds return retval; 12791da177e4SLinus Torvalds } 12801da177e4SLinus Torvalds 12811da177e4SLinus Torvalds int copy_namespace(int flags, struct task_struct *tsk) 12821da177e4SLinus Torvalds { 12831da177e4SLinus Torvalds struct namespace *namespace = tsk->namespace; 12841da177e4SLinus Torvalds struct namespace *new_ns; 12851da177e4SLinus Torvalds struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; 12861da177e4SLinus Torvalds struct fs_struct *fs = tsk->fs; 12871da177e4SLinus Torvalds struct vfsmount *p, *q; 12881da177e4SLinus Torvalds 12891da177e4SLinus Torvalds if (!namespace) 12901da177e4SLinus Torvalds return 0; 12911da177e4SLinus Torvalds 12921da177e4SLinus Torvalds get_namespace(namespace); 12931da177e4SLinus Torvalds 12941da177e4SLinus Torvalds if (!(flags & CLONE_NEWNS)) 12951da177e4SLinus Torvalds return 0; 12961da177e4SLinus Torvalds 12971da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) { 12981da177e4SLinus Torvalds put_namespace(namespace); 12991da177e4SLinus Torvalds return -EPERM; 13001da177e4SLinus Torvalds } 13011da177e4SLinus Torvalds 13021da177e4SLinus Torvalds new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL); 13031da177e4SLinus Torvalds if (!new_ns) 13041da177e4SLinus Torvalds goto out; 13051da177e4SLinus Torvalds 13061da177e4SLinus Torvalds atomic_set(&new_ns->count, 1); 13071da177e4SLinus Torvalds INIT_LIST_HEAD(&new_ns->list); 13085addc5ddSAl Viro init_waitqueue_head(&new_ns->poll); 13095addc5ddSAl Viro new_ns->event = 0; 13101da177e4SLinus Torvalds 1311390c6843SRam Pai down_write(&namespace_sem); 13121da177e4SLinus Torvalds /* First pass: copy the tree topology */ 131336341f64SRam Pai new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root, 131436341f64SRam Pai CL_EXPIRE); 13151da177e4SLinus Torvalds if (!new_ns->root) { 1316390c6843SRam Pai up_write(&namespace_sem); 13171da177e4SLinus Torvalds kfree(new_ns); 13181da177e4SLinus Torvalds goto out; 13191da177e4SLinus Torvalds } 13201da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 13211da177e4SLinus Torvalds list_add_tail(&new_ns->list, &new_ns->root->mnt_list); 13221da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 13231da177e4SLinus Torvalds 13241da177e4SLinus Torvalds /* 13251da177e4SLinus Torvalds * Second pass: switch the tsk->fs->* elements and mark new vfsmounts 13261da177e4SLinus Torvalds * as belonging to new namespace. We have already acquired a private 13271da177e4SLinus Torvalds * fs_struct, so tsk->fs->lock is not needed. 13281da177e4SLinus Torvalds */ 13291da177e4SLinus Torvalds p = namespace->root; 13301da177e4SLinus Torvalds q = new_ns->root; 13311da177e4SLinus Torvalds while (p) { 13321da177e4SLinus Torvalds q->mnt_namespace = new_ns; 13331da177e4SLinus Torvalds if (fs) { 13341da177e4SLinus Torvalds if (p == fs->rootmnt) { 13351da177e4SLinus Torvalds rootmnt = p; 13361da177e4SLinus Torvalds fs->rootmnt = mntget(q); 13371da177e4SLinus Torvalds } 13381da177e4SLinus Torvalds if (p == fs->pwdmnt) { 13391da177e4SLinus Torvalds pwdmnt = p; 13401da177e4SLinus Torvalds fs->pwdmnt = mntget(q); 13411da177e4SLinus Torvalds } 13421da177e4SLinus Torvalds if (p == fs->altrootmnt) { 13431da177e4SLinus Torvalds altrootmnt = p; 13441da177e4SLinus Torvalds fs->altrootmnt = mntget(q); 13451da177e4SLinus Torvalds } 13461da177e4SLinus Torvalds } 13471da177e4SLinus Torvalds p = next_mnt(p, namespace->root); 13481da177e4SLinus Torvalds q = next_mnt(q, new_ns->root); 13491da177e4SLinus Torvalds } 1350390c6843SRam Pai up_write(&namespace_sem); 13511da177e4SLinus Torvalds 13521da177e4SLinus Torvalds tsk->namespace = new_ns; 13531da177e4SLinus Torvalds 13541da177e4SLinus Torvalds if (rootmnt) 13551da177e4SLinus Torvalds mntput(rootmnt); 13561da177e4SLinus Torvalds if (pwdmnt) 13571da177e4SLinus Torvalds mntput(pwdmnt); 13581da177e4SLinus Torvalds if (altrootmnt) 13591da177e4SLinus Torvalds mntput(altrootmnt); 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds put_namespace(namespace); 13621da177e4SLinus Torvalds return 0; 13631da177e4SLinus Torvalds 13641da177e4SLinus Torvalds out: 13651da177e4SLinus Torvalds put_namespace(namespace); 13661da177e4SLinus Torvalds return -ENOMEM; 13671da177e4SLinus Torvalds } 13681da177e4SLinus Torvalds 13691da177e4SLinus Torvalds asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, 13701da177e4SLinus Torvalds char __user * type, unsigned long flags, 13711da177e4SLinus Torvalds void __user * data) 13721da177e4SLinus Torvalds { 13731da177e4SLinus Torvalds int retval; 13741da177e4SLinus Torvalds unsigned long data_page; 13751da177e4SLinus Torvalds unsigned long type_page; 13761da177e4SLinus Torvalds unsigned long dev_page; 13771da177e4SLinus Torvalds char *dir_page; 13781da177e4SLinus Torvalds 13791da177e4SLinus Torvalds retval = copy_mount_options(type, &type_page); 13801da177e4SLinus Torvalds if (retval < 0) 13811da177e4SLinus Torvalds return retval; 13821da177e4SLinus Torvalds 13831da177e4SLinus Torvalds dir_page = getname(dir_name); 13841da177e4SLinus Torvalds retval = PTR_ERR(dir_page); 13851da177e4SLinus Torvalds if (IS_ERR(dir_page)) 13861da177e4SLinus Torvalds goto out1; 13871da177e4SLinus Torvalds 13881da177e4SLinus Torvalds retval = copy_mount_options(dev_name, &dev_page); 13891da177e4SLinus Torvalds if (retval < 0) 13901da177e4SLinus Torvalds goto out2; 13911da177e4SLinus Torvalds 13921da177e4SLinus Torvalds retval = copy_mount_options(data, &data_page); 13931da177e4SLinus Torvalds if (retval < 0) 13941da177e4SLinus Torvalds goto out3; 13951da177e4SLinus Torvalds 13961da177e4SLinus Torvalds lock_kernel(); 13971da177e4SLinus Torvalds retval = do_mount((char *)dev_page, dir_page, (char *)type_page, 13981da177e4SLinus Torvalds flags, (void *)data_page); 13991da177e4SLinus Torvalds unlock_kernel(); 14001da177e4SLinus Torvalds free_page(data_page); 14011da177e4SLinus Torvalds 14021da177e4SLinus Torvalds out3: 14031da177e4SLinus Torvalds free_page(dev_page); 14041da177e4SLinus Torvalds out2: 14051da177e4SLinus Torvalds putname(dir_page); 14061da177e4SLinus Torvalds out1: 14071da177e4SLinus Torvalds free_page(type_page); 14081da177e4SLinus Torvalds return retval; 14091da177e4SLinus Torvalds } 14101da177e4SLinus Torvalds 14111da177e4SLinus Torvalds /* 14121da177e4SLinus Torvalds * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. 14131da177e4SLinus Torvalds * It can block. Requires the big lock held. 14141da177e4SLinus Torvalds */ 14151da177e4SLinus Torvalds void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, 14161da177e4SLinus Torvalds struct dentry *dentry) 14171da177e4SLinus Torvalds { 14181da177e4SLinus Torvalds struct dentry *old_root; 14191da177e4SLinus Torvalds struct vfsmount *old_rootmnt; 14201da177e4SLinus Torvalds write_lock(&fs->lock); 14211da177e4SLinus Torvalds old_root = fs->root; 14221da177e4SLinus Torvalds old_rootmnt = fs->rootmnt; 14231da177e4SLinus Torvalds fs->rootmnt = mntget(mnt); 14241da177e4SLinus Torvalds fs->root = dget(dentry); 14251da177e4SLinus Torvalds write_unlock(&fs->lock); 14261da177e4SLinus Torvalds if (old_root) { 14271da177e4SLinus Torvalds dput(old_root); 14281da177e4SLinus Torvalds mntput(old_rootmnt); 14291da177e4SLinus Torvalds } 14301da177e4SLinus Torvalds } 14311da177e4SLinus Torvalds 14321da177e4SLinus Torvalds /* 14331da177e4SLinus Torvalds * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. 14341da177e4SLinus Torvalds * It can block. Requires the big lock held. 14351da177e4SLinus Torvalds */ 14361da177e4SLinus Torvalds void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, 14371da177e4SLinus Torvalds struct dentry *dentry) 14381da177e4SLinus Torvalds { 14391da177e4SLinus Torvalds struct dentry *old_pwd; 14401da177e4SLinus Torvalds struct vfsmount *old_pwdmnt; 14411da177e4SLinus Torvalds 14421da177e4SLinus Torvalds write_lock(&fs->lock); 14431da177e4SLinus Torvalds old_pwd = fs->pwd; 14441da177e4SLinus Torvalds old_pwdmnt = fs->pwdmnt; 14451da177e4SLinus Torvalds fs->pwdmnt = mntget(mnt); 14461da177e4SLinus Torvalds fs->pwd = dget(dentry); 14471da177e4SLinus Torvalds write_unlock(&fs->lock); 14481da177e4SLinus Torvalds 14491da177e4SLinus Torvalds if (old_pwd) { 14501da177e4SLinus Torvalds dput(old_pwd); 14511da177e4SLinus Torvalds mntput(old_pwdmnt); 14521da177e4SLinus Torvalds } 14531da177e4SLinus Torvalds } 14541da177e4SLinus Torvalds 14551da177e4SLinus Torvalds static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) 14561da177e4SLinus Torvalds { 14571da177e4SLinus Torvalds struct task_struct *g, *p; 14581da177e4SLinus Torvalds struct fs_struct *fs; 14591da177e4SLinus Torvalds 14601da177e4SLinus Torvalds read_lock(&tasklist_lock); 14611da177e4SLinus Torvalds do_each_thread(g, p) { 14621da177e4SLinus Torvalds task_lock(p); 14631da177e4SLinus Torvalds fs = p->fs; 14641da177e4SLinus Torvalds if (fs) { 14651da177e4SLinus Torvalds atomic_inc(&fs->count); 14661da177e4SLinus Torvalds task_unlock(p); 1467b58fed8bSRam Pai if (fs->root == old_nd->dentry 1468b58fed8bSRam Pai && fs->rootmnt == old_nd->mnt) 14691da177e4SLinus Torvalds set_fs_root(fs, new_nd->mnt, new_nd->dentry); 1470b58fed8bSRam Pai if (fs->pwd == old_nd->dentry 1471b58fed8bSRam Pai && fs->pwdmnt == old_nd->mnt) 14721da177e4SLinus Torvalds set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); 14731da177e4SLinus Torvalds put_fs_struct(fs); 14741da177e4SLinus Torvalds } else 14751da177e4SLinus Torvalds task_unlock(p); 14761da177e4SLinus Torvalds } while_each_thread(g, p); 14771da177e4SLinus Torvalds read_unlock(&tasklist_lock); 14781da177e4SLinus Torvalds } 14791da177e4SLinus Torvalds 14801da177e4SLinus Torvalds /* 14811da177e4SLinus Torvalds * pivot_root Semantics: 14821da177e4SLinus Torvalds * Moves the root file system of the current process to the directory put_old, 14831da177e4SLinus Torvalds * makes new_root as the new root file system of the current process, and sets 14841da177e4SLinus Torvalds * root/cwd of all processes which had them on the current root to new_root. 14851da177e4SLinus Torvalds * 14861da177e4SLinus Torvalds * Restrictions: 14871da177e4SLinus Torvalds * The new_root and put_old must be directories, and must not be on the 14881da177e4SLinus Torvalds * same file system as the current process root. The put_old must be 14891da177e4SLinus Torvalds * underneath new_root, i.e. adding a non-zero number of /.. to the string 14901da177e4SLinus Torvalds * pointed to by put_old must yield the same directory as new_root. No other 14911da177e4SLinus Torvalds * file system may be mounted on put_old. After all, new_root is a mountpoint. 14921da177e4SLinus Torvalds * 14931da177e4SLinus Torvalds * Notes: 14941da177e4SLinus Torvalds * - we don't move root/cwd if they are not at the root (reason: if something 14951da177e4SLinus Torvalds * cared enough to change them, it's probably wrong to force them elsewhere) 14961da177e4SLinus Torvalds * - it's okay to pick a root that isn't the root of a file system, e.g. 14971da177e4SLinus Torvalds * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, 14981da177e4SLinus Torvalds * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root 14991da177e4SLinus Torvalds * first. 15001da177e4SLinus Torvalds */ 1501b58fed8bSRam Pai asmlinkage long sys_pivot_root(const char __user * new_root, 1502b58fed8bSRam Pai const char __user * put_old) 15031da177e4SLinus Torvalds { 15041da177e4SLinus Torvalds struct vfsmount *tmp; 15051da177e4SLinus Torvalds struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; 15061da177e4SLinus Torvalds int error; 15071da177e4SLinus Torvalds 15081da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 15091da177e4SLinus Torvalds return -EPERM; 15101da177e4SLinus Torvalds 15111da177e4SLinus Torvalds lock_kernel(); 15121da177e4SLinus Torvalds 1513b58fed8bSRam Pai error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, 1514b58fed8bSRam Pai &new_nd); 15151da177e4SLinus Torvalds if (error) 15161da177e4SLinus Torvalds goto out0; 15171da177e4SLinus Torvalds error = -EINVAL; 15181da177e4SLinus Torvalds if (!check_mnt(new_nd.mnt)) 15191da177e4SLinus Torvalds goto out1; 15201da177e4SLinus Torvalds 15211da177e4SLinus Torvalds error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd); 15221da177e4SLinus Torvalds if (error) 15231da177e4SLinus Torvalds goto out1; 15241da177e4SLinus Torvalds 15251da177e4SLinus Torvalds error = security_sb_pivotroot(&old_nd, &new_nd); 15261da177e4SLinus Torvalds if (error) { 15271da177e4SLinus Torvalds path_release(&old_nd); 15281da177e4SLinus Torvalds goto out1; 15291da177e4SLinus Torvalds } 15301da177e4SLinus Torvalds 15311da177e4SLinus Torvalds read_lock(¤t->fs->lock); 15321da177e4SLinus Torvalds user_nd.mnt = mntget(current->fs->rootmnt); 15331da177e4SLinus Torvalds user_nd.dentry = dget(current->fs->root); 15341da177e4SLinus Torvalds read_unlock(¤t->fs->lock); 1535390c6843SRam Pai down_write(&namespace_sem); 15361da177e4SLinus Torvalds down(&old_nd.dentry->d_inode->i_sem); 15371da177e4SLinus Torvalds error = -EINVAL; 153821444403SRam Pai if (IS_MNT_SHARED(old_nd.mnt) || 153921444403SRam Pai IS_MNT_SHARED(new_nd.mnt->mnt_parent) || 154021444403SRam Pai IS_MNT_SHARED(user_nd.mnt->mnt_parent)) 154121444403SRam Pai goto out2; 15421da177e4SLinus Torvalds if (!check_mnt(user_nd.mnt)) 15431da177e4SLinus Torvalds goto out2; 15441da177e4SLinus Torvalds error = -ENOENT; 15451da177e4SLinus Torvalds if (IS_DEADDIR(new_nd.dentry->d_inode)) 15461da177e4SLinus Torvalds goto out2; 15471da177e4SLinus Torvalds if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) 15481da177e4SLinus Torvalds goto out2; 15491da177e4SLinus Torvalds if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) 15501da177e4SLinus Torvalds goto out2; 15511da177e4SLinus Torvalds error = -EBUSY; 15521da177e4SLinus Torvalds if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) 15531da177e4SLinus Torvalds goto out2; /* loop, on the same file system */ 15541da177e4SLinus Torvalds error = -EINVAL; 15551da177e4SLinus Torvalds if (user_nd.mnt->mnt_root != user_nd.dentry) 15561da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 15570bb6fcc1SMiklos Szeredi if (user_nd.mnt->mnt_parent == user_nd.mnt) 15580bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 15591da177e4SLinus Torvalds if (new_nd.mnt->mnt_root != new_nd.dentry) 15601da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 15610bb6fcc1SMiklos Szeredi if (new_nd.mnt->mnt_parent == new_nd.mnt) 15620bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 15631da177e4SLinus Torvalds tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ 15641da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 15651da177e4SLinus Torvalds if (tmp != new_nd.mnt) { 15661da177e4SLinus Torvalds for (;;) { 15671da177e4SLinus Torvalds if (tmp->mnt_parent == tmp) 15681da177e4SLinus Torvalds goto out3; /* already mounted on put_old */ 15691da177e4SLinus Torvalds if (tmp->mnt_parent == new_nd.mnt) 15701da177e4SLinus Torvalds break; 15711da177e4SLinus Torvalds tmp = tmp->mnt_parent; 15721da177e4SLinus Torvalds } 15731da177e4SLinus Torvalds if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) 15741da177e4SLinus Torvalds goto out3; 15751da177e4SLinus Torvalds } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) 15761da177e4SLinus Torvalds goto out3; 15771da177e4SLinus Torvalds detach_mnt(new_nd.mnt, &parent_nd); 15781da177e4SLinus Torvalds detach_mnt(user_nd.mnt, &root_parent); 15791da177e4SLinus Torvalds attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ 15801da177e4SLinus Torvalds attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ 15815addc5ddSAl Viro touch_namespace(current->namespace); 15821da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 15831da177e4SLinus Torvalds chroot_fs_refs(&user_nd, &new_nd); 15841da177e4SLinus Torvalds security_sb_post_pivotroot(&user_nd, &new_nd); 15851da177e4SLinus Torvalds error = 0; 15861da177e4SLinus Torvalds path_release(&root_parent); 15871da177e4SLinus Torvalds path_release(&parent_nd); 15881da177e4SLinus Torvalds out2: 15891da177e4SLinus Torvalds up(&old_nd.dentry->d_inode->i_sem); 1590390c6843SRam Pai up_write(&namespace_sem); 15911da177e4SLinus Torvalds path_release(&user_nd); 15921da177e4SLinus Torvalds path_release(&old_nd); 15931da177e4SLinus Torvalds out1: 15941da177e4SLinus Torvalds path_release(&new_nd); 15951da177e4SLinus Torvalds out0: 15961da177e4SLinus Torvalds unlock_kernel(); 15971da177e4SLinus Torvalds return error; 15981da177e4SLinus Torvalds out3: 15991da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 16001da177e4SLinus Torvalds goto out2; 16011da177e4SLinus Torvalds } 16021da177e4SLinus Torvalds 16031da177e4SLinus Torvalds static void __init init_mount_tree(void) 16041da177e4SLinus Torvalds { 16051da177e4SLinus Torvalds struct vfsmount *mnt; 16061da177e4SLinus Torvalds struct namespace *namespace; 16071da177e4SLinus Torvalds struct task_struct *g, *p; 16081da177e4SLinus Torvalds 16091da177e4SLinus Torvalds mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); 16101da177e4SLinus Torvalds if (IS_ERR(mnt)) 16111da177e4SLinus Torvalds panic("Can't create rootfs"); 16121da177e4SLinus Torvalds namespace = kmalloc(sizeof(*namespace), GFP_KERNEL); 16131da177e4SLinus Torvalds if (!namespace) 16141da177e4SLinus Torvalds panic("Can't allocate initial namespace"); 16151da177e4SLinus Torvalds atomic_set(&namespace->count, 1); 16161da177e4SLinus Torvalds INIT_LIST_HEAD(&namespace->list); 16175addc5ddSAl Viro init_waitqueue_head(&namespace->poll); 16185addc5ddSAl Viro namespace->event = 0; 16191da177e4SLinus Torvalds list_add(&mnt->mnt_list, &namespace->list); 16201da177e4SLinus Torvalds namespace->root = mnt; 16211da177e4SLinus Torvalds mnt->mnt_namespace = namespace; 16221da177e4SLinus Torvalds 16231da177e4SLinus Torvalds init_task.namespace = namespace; 16241da177e4SLinus Torvalds read_lock(&tasklist_lock); 16251da177e4SLinus Torvalds do_each_thread(g, p) { 16261da177e4SLinus Torvalds get_namespace(namespace); 16271da177e4SLinus Torvalds p->namespace = namespace; 16281da177e4SLinus Torvalds } while_each_thread(g, p); 16291da177e4SLinus Torvalds read_unlock(&tasklist_lock); 16301da177e4SLinus Torvalds 16311da177e4SLinus Torvalds set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root); 16321da177e4SLinus Torvalds set_fs_root(current->fs, namespace->root, namespace->root->mnt_root); 16331da177e4SLinus Torvalds } 16341da177e4SLinus Torvalds 16351da177e4SLinus Torvalds void __init mnt_init(unsigned long mempages) 16361da177e4SLinus Torvalds { 16371da177e4SLinus Torvalds struct list_head *d; 16381da177e4SLinus Torvalds unsigned int nr_hash; 16391da177e4SLinus Torvalds int i; 16401da177e4SLinus Torvalds 1641390c6843SRam Pai init_rwsem(&namespace_sem); 1642390c6843SRam Pai 16431da177e4SLinus Torvalds mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), 16441da177e4SLinus Torvalds 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL, NULL); 16451da177e4SLinus Torvalds 1646b58fed8bSRam Pai mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); 16471da177e4SLinus Torvalds 16481da177e4SLinus Torvalds if (!mount_hashtable) 16491da177e4SLinus Torvalds panic("Failed to allocate mount hash table\n"); 16501da177e4SLinus Torvalds 16511da177e4SLinus Torvalds /* 16521da177e4SLinus Torvalds * Find the power-of-two list-heads that can fit into the allocation.. 16531da177e4SLinus Torvalds * We don't guarantee that "sizeof(struct list_head)" is necessarily 16541da177e4SLinus Torvalds * a power-of-two. 16551da177e4SLinus Torvalds */ 16561da177e4SLinus Torvalds nr_hash = PAGE_SIZE / sizeof(struct list_head); 16571da177e4SLinus Torvalds hash_bits = 0; 16581da177e4SLinus Torvalds do { 16591da177e4SLinus Torvalds hash_bits++; 16601da177e4SLinus Torvalds } while ((nr_hash >> hash_bits) != 0); 16611da177e4SLinus Torvalds hash_bits--; 16621da177e4SLinus Torvalds 16631da177e4SLinus Torvalds /* 16641da177e4SLinus Torvalds * Re-calculate the actual number of entries and the mask 16651da177e4SLinus Torvalds * from the number of bits we can fit. 16661da177e4SLinus Torvalds */ 16671da177e4SLinus Torvalds nr_hash = 1UL << hash_bits; 16681da177e4SLinus Torvalds hash_mask = nr_hash - 1; 16691da177e4SLinus Torvalds 16701da177e4SLinus Torvalds printk("Mount-cache hash table entries: %d\n", nr_hash); 16711da177e4SLinus Torvalds 16721da177e4SLinus Torvalds /* And initialize the newly allocated array */ 16731da177e4SLinus Torvalds d = mount_hashtable; 16741da177e4SLinus Torvalds i = nr_hash; 16751da177e4SLinus Torvalds do { 16761da177e4SLinus Torvalds INIT_LIST_HEAD(d); 16771da177e4SLinus Torvalds d++; 16781da177e4SLinus Torvalds i--; 16791da177e4SLinus Torvalds } while (i); 16801da177e4SLinus Torvalds sysfs_init(); 16811da177e4SLinus Torvalds init_rootfs(); 16821da177e4SLinus Torvalds init_mount_tree(); 16831da177e4SLinus Torvalds } 16841da177e4SLinus Torvalds 16851da177e4SLinus Torvalds void __put_namespace(struct namespace *namespace) 16861da177e4SLinus Torvalds { 16871ce88cf4SMiklos Szeredi struct vfsmount *root = namespace->root; 168870fbcdf4SRam Pai LIST_HEAD(umount_list); 16891ce88cf4SMiklos Szeredi namespace->root = NULL; 16901ce88cf4SMiklos Szeredi spin_unlock(&vfsmount_lock); 1691390c6843SRam Pai down_write(&namespace_sem); 16921da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 1693a05964f3SRam Pai umount_tree(root, 0, &umount_list); 16941da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1695390c6843SRam Pai up_write(&namespace_sem); 169670fbcdf4SRam Pai release_mounts(&umount_list); 16971da177e4SLinus Torvalds kfree(namespace); 16981da177e4SLinus Torvalds } 1699