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); 701da177e4SLinus Torvalds if (name) { 711da177e4SLinus Torvalds int size = strlen(name) + 1; 721da177e4SLinus Torvalds char *newname = kmalloc(size, GFP_KERNEL); 731da177e4SLinus Torvalds if (newname) { 741da177e4SLinus Torvalds memcpy(newname, name, size); 751da177e4SLinus Torvalds mnt->mnt_devname = newname; 761da177e4SLinus Torvalds } 771da177e4SLinus Torvalds } 781da177e4SLinus Torvalds } 791da177e4SLinus Torvalds return mnt; 801da177e4SLinus Torvalds } 811da177e4SLinus Torvalds 821da177e4SLinus Torvalds void free_vfsmnt(struct vfsmount *mnt) 831da177e4SLinus Torvalds { 841da177e4SLinus Torvalds kfree(mnt->mnt_devname); 851da177e4SLinus Torvalds kmem_cache_free(mnt_cache, mnt); 861da177e4SLinus Torvalds } 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* 891da177e4SLinus Torvalds * Now, lookup_mnt increments the ref count before returning 901da177e4SLinus Torvalds * the vfsmount struct. 911da177e4SLinus Torvalds */ 921da177e4SLinus Torvalds struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) 931da177e4SLinus Torvalds { 941da177e4SLinus Torvalds struct list_head *head = mount_hashtable + hash(mnt, dentry); 951da177e4SLinus Torvalds struct list_head *tmp = head; 961da177e4SLinus Torvalds struct vfsmount *p, *found = NULL; 971da177e4SLinus Torvalds 981da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 991da177e4SLinus Torvalds for (;;) { 1001da177e4SLinus Torvalds tmp = tmp->next; 1011da177e4SLinus Torvalds p = NULL; 1021da177e4SLinus Torvalds if (tmp == head) 1031da177e4SLinus Torvalds break; 1041da177e4SLinus Torvalds p = list_entry(tmp, struct vfsmount, mnt_hash); 1051da177e4SLinus Torvalds if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { 1061da177e4SLinus Torvalds found = mntget(p); 1071da177e4SLinus Torvalds break; 1081da177e4SLinus Torvalds } 1091da177e4SLinus Torvalds } 1101da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1111da177e4SLinus Torvalds return found; 1121da177e4SLinus Torvalds } 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds static inline int check_mnt(struct vfsmount *mnt) 1151da177e4SLinus Torvalds { 1161da177e4SLinus Torvalds return mnt->mnt_namespace == current->namespace; 1171da177e4SLinus Torvalds } 1181da177e4SLinus Torvalds 1195addc5ddSAl Viro static void touch_namespace(struct namespace *ns) 1205addc5ddSAl Viro { 1215addc5ddSAl Viro if (ns) { 1225addc5ddSAl Viro ns->event = ++event; 1235addc5ddSAl Viro wake_up_interruptible(&ns->poll); 1245addc5ddSAl Viro } 1255addc5ddSAl Viro } 1265addc5ddSAl Viro 1275addc5ddSAl Viro static void __touch_namespace(struct namespace *ns) 1285addc5ddSAl Viro { 1295addc5ddSAl Viro if (ns && ns->event != event) { 1305addc5ddSAl Viro ns->event = event; 1315addc5ddSAl Viro wake_up_interruptible(&ns->poll); 1325addc5ddSAl Viro } 1335addc5ddSAl Viro } 1345addc5ddSAl Viro 1351da177e4SLinus Torvalds static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) 1361da177e4SLinus Torvalds { 1371da177e4SLinus Torvalds old_nd->dentry = mnt->mnt_mountpoint; 1381da177e4SLinus Torvalds old_nd->mnt = mnt->mnt_parent; 1391da177e4SLinus Torvalds mnt->mnt_parent = mnt; 1401da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 1411da177e4SLinus Torvalds list_del_init(&mnt->mnt_child); 1421da177e4SLinus Torvalds list_del_init(&mnt->mnt_hash); 1431da177e4SLinus Torvalds old_nd->dentry->d_mounted--; 1441da177e4SLinus Torvalds } 1451da177e4SLinus Torvalds 146b90fa9aeSRam Pai void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, 147b90fa9aeSRam Pai struct vfsmount *child_mnt) 148b90fa9aeSRam Pai { 149b90fa9aeSRam Pai child_mnt->mnt_parent = mntget(mnt); 150b90fa9aeSRam Pai child_mnt->mnt_mountpoint = dget(dentry); 151b90fa9aeSRam Pai dentry->d_mounted++; 152b90fa9aeSRam Pai } 153b90fa9aeSRam Pai 1541da177e4SLinus Torvalds static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) 1551da177e4SLinus Torvalds { 156b90fa9aeSRam Pai mnt_set_mountpoint(nd->mnt, nd->dentry, mnt); 157b90fa9aeSRam Pai list_add_tail(&mnt->mnt_hash, mount_hashtable + 158b90fa9aeSRam Pai hash(nd->mnt, nd->dentry)); 1591da177e4SLinus Torvalds list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); 160b90fa9aeSRam Pai } 161b90fa9aeSRam Pai 162b90fa9aeSRam Pai /* 163b90fa9aeSRam Pai * the caller must hold vfsmount_lock 164b90fa9aeSRam Pai */ 165b90fa9aeSRam Pai static void commit_tree(struct vfsmount *mnt) 166b90fa9aeSRam Pai { 167b90fa9aeSRam Pai struct vfsmount *parent = mnt->mnt_parent; 168b90fa9aeSRam Pai struct vfsmount *m; 169b90fa9aeSRam Pai LIST_HEAD(head); 170b90fa9aeSRam Pai struct namespace *n = parent->mnt_namespace; 171b90fa9aeSRam Pai 172b90fa9aeSRam Pai BUG_ON(parent == mnt); 173b90fa9aeSRam Pai 174b90fa9aeSRam Pai list_add_tail(&head, &mnt->mnt_list); 175b90fa9aeSRam Pai list_for_each_entry(m, &head, mnt_list) 176b90fa9aeSRam Pai m->mnt_namespace = n; 177b90fa9aeSRam Pai list_splice(&head, n->list.prev); 178b90fa9aeSRam Pai 179b90fa9aeSRam Pai list_add_tail(&mnt->mnt_hash, mount_hashtable + 180b90fa9aeSRam Pai hash(parent, mnt->mnt_mountpoint)); 181b90fa9aeSRam Pai list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); 182b90fa9aeSRam Pai touch_namespace(n); 1831da177e4SLinus Torvalds } 1841da177e4SLinus Torvalds 1851da177e4SLinus Torvalds static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) 1861da177e4SLinus Torvalds { 1871da177e4SLinus Torvalds struct list_head *next = p->mnt_mounts.next; 1881da177e4SLinus Torvalds if (next == &p->mnt_mounts) { 1891da177e4SLinus Torvalds while (1) { 1901da177e4SLinus Torvalds if (p == root) 1911da177e4SLinus Torvalds return NULL; 1921da177e4SLinus Torvalds next = p->mnt_child.next; 1931da177e4SLinus Torvalds if (next != &p->mnt_parent->mnt_mounts) 1941da177e4SLinus Torvalds break; 1951da177e4SLinus Torvalds p = p->mnt_parent; 1961da177e4SLinus Torvalds } 1971da177e4SLinus Torvalds } 1981da177e4SLinus Torvalds return list_entry(next, struct vfsmount, mnt_child); 1991da177e4SLinus Torvalds } 2001da177e4SLinus Torvalds 20136341f64SRam Pai static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, 20236341f64SRam Pai int flag) 2031da177e4SLinus Torvalds { 2041da177e4SLinus Torvalds struct super_block *sb = old->mnt_sb; 2051da177e4SLinus Torvalds struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); 2061da177e4SLinus Torvalds 2071da177e4SLinus Torvalds if (mnt) { 2081da177e4SLinus Torvalds mnt->mnt_flags = old->mnt_flags; 2091da177e4SLinus Torvalds atomic_inc(&sb->s_active); 2101da177e4SLinus Torvalds mnt->mnt_sb = sb; 2111da177e4SLinus Torvalds mnt->mnt_root = dget(root); 2121da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 2131da177e4SLinus Torvalds mnt->mnt_parent = mnt; 214b90fa9aeSRam Pai 215b90fa9aeSRam Pai if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) 216b90fa9aeSRam Pai list_add(&mnt->mnt_share, &old->mnt_share); 217b90fa9aeSRam Pai if (flag & CL_MAKE_SHARED) 218b90fa9aeSRam Pai set_mnt_shared(mnt); 2191da177e4SLinus Torvalds 2201da177e4SLinus Torvalds /* stick the duplicate mount on the same expiry list 2211da177e4SLinus Torvalds * as the original if that was on one */ 22236341f64SRam Pai if (flag & CL_EXPIRE) { 2231da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 22455e700b9SMiklos Szeredi if (!list_empty(&old->mnt_expire)) 22555e700b9SMiklos Szeredi list_add(&mnt->mnt_expire, &old->mnt_expire); 2261da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 2271da177e4SLinus Torvalds } 22836341f64SRam Pai } 2291da177e4SLinus Torvalds return mnt; 2301da177e4SLinus Torvalds } 2311da177e4SLinus Torvalds 2327b7b1aceSAl Viro static inline void __mntput(struct vfsmount *mnt) 2331da177e4SLinus Torvalds { 2341da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 2351da177e4SLinus Torvalds dput(mnt->mnt_root); 2361da177e4SLinus Torvalds free_vfsmnt(mnt); 2371da177e4SLinus Torvalds deactivate_super(sb); 2381da177e4SLinus Torvalds } 2391da177e4SLinus Torvalds 2407b7b1aceSAl Viro void mntput_no_expire(struct vfsmount *mnt) 2417b7b1aceSAl Viro { 2427b7b1aceSAl Viro repeat: 2437b7b1aceSAl Viro if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { 2447b7b1aceSAl Viro if (likely(!mnt->mnt_pinned)) { 2457b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2467b7b1aceSAl Viro __mntput(mnt); 2477b7b1aceSAl Viro return; 2487b7b1aceSAl Viro } 2497b7b1aceSAl Viro atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); 2507b7b1aceSAl Viro mnt->mnt_pinned = 0; 2517b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2527b7b1aceSAl Viro acct_auto_close_mnt(mnt); 2537b7b1aceSAl Viro security_sb_umount_close(mnt); 2547b7b1aceSAl Viro goto repeat; 2557b7b1aceSAl Viro } 2567b7b1aceSAl Viro } 2577b7b1aceSAl Viro 2587b7b1aceSAl Viro EXPORT_SYMBOL(mntput_no_expire); 2597b7b1aceSAl Viro 2607b7b1aceSAl Viro void mnt_pin(struct vfsmount *mnt) 2617b7b1aceSAl Viro { 2627b7b1aceSAl Viro spin_lock(&vfsmount_lock); 2637b7b1aceSAl Viro mnt->mnt_pinned++; 2647b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2657b7b1aceSAl Viro } 2667b7b1aceSAl Viro 2677b7b1aceSAl Viro EXPORT_SYMBOL(mnt_pin); 2687b7b1aceSAl Viro 2697b7b1aceSAl Viro void mnt_unpin(struct vfsmount *mnt) 2707b7b1aceSAl Viro { 2717b7b1aceSAl Viro spin_lock(&vfsmount_lock); 2727b7b1aceSAl Viro if (mnt->mnt_pinned) { 2737b7b1aceSAl Viro atomic_inc(&mnt->mnt_count); 2747b7b1aceSAl Viro mnt->mnt_pinned--; 2757b7b1aceSAl Viro } 2767b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2777b7b1aceSAl Viro } 2787b7b1aceSAl Viro 2797b7b1aceSAl Viro EXPORT_SYMBOL(mnt_unpin); 2801da177e4SLinus Torvalds 2811da177e4SLinus Torvalds /* iterator */ 2821da177e4SLinus Torvalds static void *m_start(struct seq_file *m, loff_t *pos) 2831da177e4SLinus Torvalds { 2841da177e4SLinus Torvalds struct namespace *n = m->private; 2851da177e4SLinus Torvalds struct list_head *p; 2861da177e4SLinus Torvalds loff_t l = *pos; 2871da177e4SLinus Torvalds 288390c6843SRam Pai down_read(&namespace_sem); 2891da177e4SLinus Torvalds list_for_each(p, &n->list) 2901da177e4SLinus Torvalds if (!l--) 2911da177e4SLinus Torvalds return list_entry(p, struct vfsmount, mnt_list); 2921da177e4SLinus Torvalds return NULL; 2931da177e4SLinus Torvalds } 2941da177e4SLinus Torvalds 2951da177e4SLinus Torvalds static void *m_next(struct seq_file *m, void *v, loff_t *pos) 2961da177e4SLinus Torvalds { 2971da177e4SLinus Torvalds struct namespace *n = m->private; 2981da177e4SLinus Torvalds struct list_head *p = ((struct vfsmount *)v)->mnt_list.next; 2991da177e4SLinus Torvalds (*pos)++; 3001da177e4SLinus Torvalds return p == &n->list ? NULL : list_entry(p, struct vfsmount, mnt_list); 3011da177e4SLinus Torvalds } 3021da177e4SLinus Torvalds 3031da177e4SLinus Torvalds static void m_stop(struct seq_file *m, void *v) 3041da177e4SLinus Torvalds { 305390c6843SRam Pai up_read(&namespace_sem); 3061da177e4SLinus Torvalds } 3071da177e4SLinus Torvalds 3081da177e4SLinus Torvalds static inline void mangle(struct seq_file *m, const char *s) 3091da177e4SLinus Torvalds { 3101da177e4SLinus Torvalds seq_escape(m, s, " \t\n\\"); 3111da177e4SLinus Torvalds } 3121da177e4SLinus Torvalds 3131da177e4SLinus Torvalds static int show_vfsmnt(struct seq_file *m, void *v) 3141da177e4SLinus Torvalds { 3151da177e4SLinus Torvalds struct vfsmount *mnt = v; 3161da177e4SLinus Torvalds int err = 0; 3171da177e4SLinus Torvalds static struct proc_fs_info { 3181da177e4SLinus Torvalds int flag; 3191da177e4SLinus Torvalds char *str; 3201da177e4SLinus Torvalds } fs_info[] = { 3211da177e4SLinus Torvalds { MS_SYNCHRONOUS, ",sync" }, 3221da177e4SLinus Torvalds { MS_DIRSYNC, ",dirsync" }, 3231da177e4SLinus Torvalds { MS_MANDLOCK, ",mand" }, 3241da177e4SLinus Torvalds { MS_NOATIME, ",noatime" }, 3251da177e4SLinus Torvalds { MS_NODIRATIME, ",nodiratime" }, 3261da177e4SLinus Torvalds { 0, NULL } 3271da177e4SLinus Torvalds }; 3281da177e4SLinus Torvalds static struct proc_fs_info mnt_info[] = { 3291da177e4SLinus Torvalds { MNT_NOSUID, ",nosuid" }, 3301da177e4SLinus Torvalds { MNT_NODEV, ",nodev" }, 3311da177e4SLinus Torvalds { MNT_NOEXEC, ",noexec" }, 3321da177e4SLinus Torvalds { 0, NULL } 3331da177e4SLinus Torvalds }; 3341da177e4SLinus Torvalds struct proc_fs_info *fs_infop; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); 3371da177e4SLinus Torvalds seq_putc(m, ' '); 3381da177e4SLinus Torvalds seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); 3391da177e4SLinus Torvalds seq_putc(m, ' '); 3401da177e4SLinus Torvalds mangle(m, mnt->mnt_sb->s_type->name); 3411da177e4SLinus Torvalds seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); 3421da177e4SLinus Torvalds for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { 3431da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & fs_infop->flag) 3441da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 3451da177e4SLinus Torvalds } 3461da177e4SLinus Torvalds for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { 3471da177e4SLinus Torvalds if (mnt->mnt_flags & fs_infop->flag) 3481da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 3491da177e4SLinus Torvalds } 3501da177e4SLinus Torvalds if (mnt->mnt_sb->s_op->show_options) 3511da177e4SLinus Torvalds err = mnt->mnt_sb->s_op->show_options(m, mnt); 3521da177e4SLinus Torvalds seq_puts(m, " 0 0\n"); 3531da177e4SLinus Torvalds return err; 3541da177e4SLinus Torvalds } 3551da177e4SLinus Torvalds 3561da177e4SLinus Torvalds struct seq_operations mounts_op = { 3571da177e4SLinus Torvalds .start = m_start, 3581da177e4SLinus Torvalds .next = m_next, 3591da177e4SLinus Torvalds .stop = m_stop, 3601da177e4SLinus Torvalds .show = show_vfsmnt 3611da177e4SLinus Torvalds }; 3621da177e4SLinus Torvalds 3631da177e4SLinus Torvalds /** 3641da177e4SLinus Torvalds * may_umount_tree - check if a mount tree is busy 3651da177e4SLinus Torvalds * @mnt: root of mount tree 3661da177e4SLinus Torvalds * 3671da177e4SLinus Torvalds * This is called to check if a tree of mounts has any 3681da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts that are 3691da177e4SLinus Torvalds * busy. 3701da177e4SLinus Torvalds */ 3711da177e4SLinus Torvalds int may_umount_tree(struct vfsmount *mnt) 3721da177e4SLinus Torvalds { 37336341f64SRam Pai int actual_refs = 0; 37436341f64SRam Pai int minimum_refs = 0; 37536341f64SRam Pai struct vfsmount *p; 3761da177e4SLinus Torvalds 3771da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 37836341f64SRam Pai for (p = mnt; p; p = next_mnt(p, mnt)) { 3791da177e4SLinus Torvalds actual_refs += atomic_read(&p->mnt_count); 3801da177e4SLinus Torvalds minimum_refs += 2; 3811da177e4SLinus Torvalds } 3821da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 3831da177e4SLinus Torvalds 3841da177e4SLinus Torvalds if (actual_refs > minimum_refs) 3851da177e4SLinus Torvalds return -EBUSY; 3861da177e4SLinus Torvalds 3871da177e4SLinus Torvalds return 0; 3881da177e4SLinus Torvalds } 3891da177e4SLinus Torvalds 3901da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount_tree); 3911da177e4SLinus Torvalds 3921da177e4SLinus Torvalds /** 3931da177e4SLinus Torvalds * may_umount - check if a mount point is busy 3941da177e4SLinus Torvalds * @mnt: root of mount 3951da177e4SLinus Torvalds * 3961da177e4SLinus Torvalds * This is called to check if a mount point has any 3971da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts. If the 3981da177e4SLinus Torvalds * mount has sub mounts this will return busy 3991da177e4SLinus Torvalds * regardless of whether the sub mounts are busy. 4001da177e4SLinus Torvalds * 4011da177e4SLinus Torvalds * Doesn't take quota and stuff into account. IOW, in some cases it will 4021da177e4SLinus Torvalds * give false negatives. The main reason why it's here is that we need 4031da177e4SLinus Torvalds * a non-destructive way to look for easily umountable filesystems. 4041da177e4SLinus Torvalds */ 4051da177e4SLinus Torvalds int may_umount(struct vfsmount *mnt) 4061da177e4SLinus Torvalds { 4071da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) > 2) 4081da177e4SLinus Torvalds return -EBUSY; 4091da177e4SLinus Torvalds return 0; 4101da177e4SLinus Torvalds } 4111da177e4SLinus Torvalds 4121da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount); 4131da177e4SLinus Torvalds 414b90fa9aeSRam Pai void release_mounts(struct list_head *head) 4151da177e4SLinus Torvalds { 41670fbcdf4SRam Pai struct vfsmount *mnt; 41770fbcdf4SRam Pai while(!list_empty(head)) { 41870fbcdf4SRam Pai mnt = list_entry(head->next, struct vfsmount, mnt_hash); 41970fbcdf4SRam Pai list_del_init(&mnt->mnt_hash); 42070fbcdf4SRam Pai if (mnt->mnt_parent != mnt) { 42170fbcdf4SRam Pai struct dentry *dentry; 42270fbcdf4SRam Pai struct vfsmount *m; 42370fbcdf4SRam Pai spin_lock(&vfsmount_lock); 42470fbcdf4SRam Pai dentry = mnt->mnt_mountpoint; 42570fbcdf4SRam Pai m = mnt->mnt_parent; 42670fbcdf4SRam Pai mnt->mnt_mountpoint = mnt->mnt_root; 42770fbcdf4SRam Pai mnt->mnt_parent = mnt; 4281da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 42970fbcdf4SRam Pai dput(dentry); 43070fbcdf4SRam Pai mntput(m); 4311da177e4SLinus Torvalds } 4321da177e4SLinus Torvalds mntput(mnt); 43370fbcdf4SRam Pai } 43470fbcdf4SRam Pai } 43570fbcdf4SRam Pai 436b90fa9aeSRam Pai void umount_tree(struct vfsmount *mnt, struct list_head *kill) 43770fbcdf4SRam Pai { 43870fbcdf4SRam Pai struct vfsmount *p; 43970fbcdf4SRam Pai 44070fbcdf4SRam Pai for (p = mnt; p; p = next_mnt(p, mnt)) { 44170fbcdf4SRam Pai list_del(&p->mnt_hash); 44270fbcdf4SRam Pai list_add(&p->mnt_hash, kill); 44370fbcdf4SRam Pai } 44470fbcdf4SRam Pai 44570fbcdf4SRam Pai list_for_each_entry(p, kill, mnt_hash) { 44670fbcdf4SRam Pai list_del_init(&p->mnt_expire); 44770fbcdf4SRam Pai list_del_init(&p->mnt_list); 44870fbcdf4SRam Pai __touch_namespace(p->mnt_namespace); 44970fbcdf4SRam Pai p->mnt_namespace = NULL; 45070fbcdf4SRam Pai list_del_init(&p->mnt_child); 45170fbcdf4SRam Pai if (p->mnt_parent != p) 45270fbcdf4SRam Pai mnt->mnt_mountpoint->d_mounted--; 4531da177e4SLinus Torvalds } 4541da177e4SLinus Torvalds } 4551da177e4SLinus Torvalds 4561da177e4SLinus Torvalds static int do_umount(struct vfsmount *mnt, int flags) 4571da177e4SLinus Torvalds { 4581da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 4591da177e4SLinus Torvalds int retval; 46070fbcdf4SRam Pai LIST_HEAD(umount_list); 4611da177e4SLinus Torvalds 4621da177e4SLinus Torvalds retval = security_sb_umount(mnt, flags); 4631da177e4SLinus Torvalds if (retval) 4641da177e4SLinus Torvalds return retval; 4651da177e4SLinus Torvalds 4661da177e4SLinus Torvalds /* 4671da177e4SLinus Torvalds * Allow userspace to request a mountpoint be expired rather than 4681da177e4SLinus Torvalds * unmounting unconditionally. Unmount only happens if: 4691da177e4SLinus Torvalds * (1) the mark is already set (the mark is cleared by mntput()) 4701da177e4SLinus Torvalds * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] 4711da177e4SLinus Torvalds */ 4721da177e4SLinus Torvalds if (flags & MNT_EXPIRE) { 4731da177e4SLinus Torvalds if (mnt == current->fs->rootmnt || 4741da177e4SLinus Torvalds flags & (MNT_FORCE | MNT_DETACH)) 4751da177e4SLinus Torvalds return -EINVAL; 4761da177e4SLinus Torvalds 4771da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) != 2) 4781da177e4SLinus Torvalds return -EBUSY; 4791da177e4SLinus Torvalds 4801da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1)) 4811da177e4SLinus Torvalds return -EAGAIN; 4821da177e4SLinus Torvalds } 4831da177e4SLinus Torvalds 4841da177e4SLinus Torvalds /* 4851da177e4SLinus Torvalds * If we may have to abort operations to get out of this 4861da177e4SLinus Torvalds * mount, and they will themselves hold resources we must 4871da177e4SLinus Torvalds * allow the fs to do things. In the Unix tradition of 4881da177e4SLinus Torvalds * 'Gee thats tricky lets do it in userspace' the umount_begin 4891da177e4SLinus Torvalds * might fail to complete on the first run through as other tasks 4901da177e4SLinus Torvalds * must return, and the like. Thats for the mount program to worry 4911da177e4SLinus Torvalds * about for the moment. 4921da177e4SLinus Torvalds */ 4931da177e4SLinus Torvalds 4941da177e4SLinus Torvalds lock_kernel(); 4951da177e4SLinus Torvalds if ((flags & MNT_FORCE) && sb->s_op->umount_begin) 4961da177e4SLinus Torvalds sb->s_op->umount_begin(sb); 4971da177e4SLinus Torvalds unlock_kernel(); 4981da177e4SLinus Torvalds 4991da177e4SLinus Torvalds /* 5001da177e4SLinus Torvalds * No sense to grab the lock for this test, but test itself looks 5011da177e4SLinus Torvalds * somewhat bogus. Suggestions for better replacement? 5021da177e4SLinus Torvalds * Ho-hum... In principle, we might treat that as umount + switch 5031da177e4SLinus Torvalds * to rootfs. GC would eventually take care of the old vfsmount. 5041da177e4SLinus Torvalds * Actually it makes sense, especially if rootfs would contain a 5051da177e4SLinus Torvalds * /reboot - static binary that would close all descriptors and 5061da177e4SLinus Torvalds * call reboot(9). Then init(8) could umount root and exec /reboot. 5071da177e4SLinus Torvalds */ 5081da177e4SLinus Torvalds if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { 5091da177e4SLinus Torvalds /* 5101da177e4SLinus Torvalds * Special case for "unmounting" root ... 5111da177e4SLinus Torvalds * we just try to remount it readonly. 5121da177e4SLinus Torvalds */ 5131da177e4SLinus Torvalds down_write(&sb->s_umount); 5141da177e4SLinus Torvalds if (!(sb->s_flags & MS_RDONLY)) { 5151da177e4SLinus Torvalds lock_kernel(); 5161da177e4SLinus Torvalds DQUOT_OFF(sb); 5171da177e4SLinus Torvalds retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); 5181da177e4SLinus Torvalds unlock_kernel(); 5191da177e4SLinus Torvalds } 5201da177e4SLinus Torvalds up_write(&sb->s_umount); 5211da177e4SLinus Torvalds return retval; 5221da177e4SLinus Torvalds } 5231da177e4SLinus Torvalds 524390c6843SRam Pai down_write(&namespace_sem); 5251da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 5265addc5ddSAl Viro event++; 5271da177e4SLinus Torvalds 5281da177e4SLinus Torvalds retval = -EBUSY; 5291da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) { 5301da177e4SLinus Torvalds if (!list_empty(&mnt->mnt_list)) 53170fbcdf4SRam Pai umount_tree(mnt, &umount_list); 5321da177e4SLinus Torvalds retval = 0; 5331da177e4SLinus Torvalds } 5341da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 5351da177e4SLinus Torvalds if (retval) 5361da177e4SLinus Torvalds security_sb_umount_busy(mnt); 537390c6843SRam Pai up_write(&namespace_sem); 53870fbcdf4SRam Pai release_mounts(&umount_list); 5391da177e4SLinus Torvalds return retval; 5401da177e4SLinus Torvalds } 5411da177e4SLinus Torvalds 5421da177e4SLinus Torvalds /* 5431da177e4SLinus Torvalds * Now umount can handle mount points as well as block devices. 5441da177e4SLinus Torvalds * This is important for filesystems which use unnamed block devices. 5451da177e4SLinus Torvalds * 5461da177e4SLinus Torvalds * We now support a flag for forced unmount like the other 'big iron' 5471da177e4SLinus Torvalds * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD 5481da177e4SLinus Torvalds */ 5491da177e4SLinus Torvalds 5501da177e4SLinus Torvalds asmlinkage long sys_umount(char __user * name, int flags) 5511da177e4SLinus Torvalds { 5521da177e4SLinus Torvalds struct nameidata nd; 5531da177e4SLinus Torvalds int retval; 5541da177e4SLinus Torvalds 5551da177e4SLinus Torvalds retval = __user_walk(name, LOOKUP_FOLLOW, &nd); 5561da177e4SLinus Torvalds if (retval) 5571da177e4SLinus Torvalds goto out; 5581da177e4SLinus Torvalds retval = -EINVAL; 5591da177e4SLinus Torvalds if (nd.dentry != nd.mnt->mnt_root) 5601da177e4SLinus Torvalds goto dput_and_out; 5611da177e4SLinus Torvalds if (!check_mnt(nd.mnt)) 5621da177e4SLinus Torvalds goto dput_and_out; 5631da177e4SLinus Torvalds 5641da177e4SLinus Torvalds retval = -EPERM; 5651da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 5661da177e4SLinus Torvalds goto dput_and_out; 5671da177e4SLinus Torvalds 5681da177e4SLinus Torvalds retval = do_umount(nd.mnt, flags); 5691da177e4SLinus Torvalds dput_and_out: 5701da177e4SLinus Torvalds path_release_on_umount(&nd); 5711da177e4SLinus Torvalds out: 5721da177e4SLinus Torvalds return retval; 5731da177e4SLinus Torvalds } 5741da177e4SLinus Torvalds 5751da177e4SLinus Torvalds #ifdef __ARCH_WANT_SYS_OLDUMOUNT 5761da177e4SLinus Torvalds 5771da177e4SLinus Torvalds /* 5781da177e4SLinus Torvalds * The 2.0 compatible umount. No flags. 5791da177e4SLinus Torvalds */ 5801da177e4SLinus Torvalds asmlinkage long sys_oldumount(char __user * name) 5811da177e4SLinus Torvalds { 5821da177e4SLinus Torvalds return sys_umount(name, 0); 5831da177e4SLinus Torvalds } 5841da177e4SLinus Torvalds 5851da177e4SLinus Torvalds #endif 5861da177e4SLinus Torvalds 5871da177e4SLinus Torvalds static int mount_is_safe(struct nameidata *nd) 5881da177e4SLinus Torvalds { 5891da177e4SLinus Torvalds if (capable(CAP_SYS_ADMIN)) 5901da177e4SLinus Torvalds return 0; 5911da177e4SLinus Torvalds return -EPERM; 5921da177e4SLinus Torvalds #ifdef notyet 5931da177e4SLinus Torvalds if (S_ISLNK(nd->dentry->d_inode->i_mode)) 5941da177e4SLinus Torvalds return -EPERM; 5951da177e4SLinus Torvalds if (nd->dentry->d_inode->i_mode & S_ISVTX) { 5961da177e4SLinus Torvalds if (current->uid != nd->dentry->d_inode->i_uid) 5971da177e4SLinus Torvalds return -EPERM; 5981da177e4SLinus Torvalds } 5991da177e4SLinus Torvalds if (permission(nd->dentry->d_inode, MAY_WRITE, nd)) 6001da177e4SLinus Torvalds return -EPERM; 6011da177e4SLinus Torvalds return 0; 6021da177e4SLinus Torvalds #endif 6031da177e4SLinus Torvalds } 6041da177e4SLinus Torvalds 605b58fed8bSRam Pai static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) 6061da177e4SLinus Torvalds { 6071da177e4SLinus Torvalds while (1) { 6081da177e4SLinus Torvalds if (d == dentry) 6091da177e4SLinus Torvalds return 1; 6101da177e4SLinus Torvalds if (d == NULL || d == d->d_parent) 6111da177e4SLinus Torvalds return 0; 6121da177e4SLinus Torvalds d = d->d_parent; 6131da177e4SLinus Torvalds } 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds 616b90fa9aeSRam Pai struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, 61736341f64SRam Pai int flag) 6181da177e4SLinus Torvalds { 6191da177e4SLinus Torvalds struct vfsmount *res, *p, *q, *r, *s; 6201da177e4SLinus Torvalds struct nameidata nd; 6211da177e4SLinus Torvalds 62236341f64SRam Pai res = q = clone_mnt(mnt, dentry, flag); 6231da177e4SLinus Torvalds if (!q) 6241da177e4SLinus Torvalds goto Enomem; 6251da177e4SLinus Torvalds q->mnt_mountpoint = mnt->mnt_mountpoint; 6261da177e4SLinus Torvalds 6271da177e4SLinus Torvalds p = mnt; 628fdadd65fSDomen Puncer list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { 6291da177e4SLinus Torvalds if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) 6301da177e4SLinus Torvalds continue; 6311da177e4SLinus Torvalds 6321da177e4SLinus Torvalds for (s = r; s; s = next_mnt(s, r)) { 6331da177e4SLinus Torvalds while (p != s->mnt_parent) { 6341da177e4SLinus Torvalds p = p->mnt_parent; 6351da177e4SLinus Torvalds q = q->mnt_parent; 6361da177e4SLinus Torvalds } 6371da177e4SLinus Torvalds p = s; 6381da177e4SLinus Torvalds nd.mnt = q; 6391da177e4SLinus Torvalds nd.dentry = p->mnt_mountpoint; 64036341f64SRam Pai q = clone_mnt(p, p->mnt_root, flag); 6411da177e4SLinus Torvalds if (!q) 6421da177e4SLinus Torvalds goto Enomem; 6431da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6441da177e4SLinus Torvalds list_add_tail(&q->mnt_list, &res->mnt_list); 6451da177e4SLinus Torvalds attach_mnt(q, &nd); 6461da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6471da177e4SLinus Torvalds } 6481da177e4SLinus Torvalds } 6491da177e4SLinus Torvalds return res; 6501da177e4SLinus Torvalds Enomem: 6511da177e4SLinus Torvalds if (res) { 65270fbcdf4SRam Pai LIST_HEAD(umount_list); 6531da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 65470fbcdf4SRam Pai umount_tree(res, &umount_list); 6551da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 65670fbcdf4SRam Pai release_mounts(&umount_list); 6571da177e4SLinus Torvalds } 6581da177e4SLinus Torvalds return NULL; 6591da177e4SLinus Torvalds } 6601da177e4SLinus Torvalds 661b90fa9aeSRam Pai /* 662b90fa9aeSRam Pai * @source_mnt : mount tree to be attached 663b90fa9aeSRam Pai * @nd : place the mount tree @source_mnt is attached 66421444403SRam Pai * @parent_nd : if non-null, detach the source_mnt from its parent and 66521444403SRam Pai * store the parent mount and mountpoint dentry. 66621444403SRam Pai * (done when source_mnt is moved) 667b90fa9aeSRam Pai * 668b90fa9aeSRam Pai * NOTE: in the table below explains the semantics when a source mount 669b90fa9aeSRam Pai * of a given type is attached to a destination mount of a given type. 670b90fa9aeSRam Pai * --------------------------------------------- 671b90fa9aeSRam Pai * | BIND MOUNT OPERATION | 672b90fa9aeSRam Pai * |******************************************** 673b90fa9aeSRam Pai * | source-->| shared | private | 674b90fa9aeSRam Pai * | dest | | | 675b90fa9aeSRam Pai * | | | | | 676b90fa9aeSRam Pai * | v | | | 677b90fa9aeSRam Pai * |******************************************** 678b90fa9aeSRam Pai * | shared | shared (++) | shared (+) | 679b90fa9aeSRam Pai * | | | | 680b90fa9aeSRam Pai * |non-shared| shared (+) | private | 681b90fa9aeSRam Pai * ********************************************* 682b90fa9aeSRam Pai * A bind operation clones the source mount and mounts the clone on the 683b90fa9aeSRam Pai * destination mount. 684b90fa9aeSRam Pai * 685b90fa9aeSRam Pai * (++) the cloned mount is propagated to all the mounts in the propagation 686b90fa9aeSRam Pai * tree of the destination mount and the cloned mount is added to 687b90fa9aeSRam Pai * the peer group of the source mount. 688b90fa9aeSRam Pai * (+) the cloned mount is created under the destination mount and is marked 689b90fa9aeSRam Pai * as shared. The cloned mount is added to the peer group of the source 690b90fa9aeSRam Pai * mount. 69121444403SRam Pai * --------------------------------------------- 69221444403SRam Pai * | MOVE MOUNT OPERATION | 69321444403SRam Pai * |******************************************** 69421444403SRam Pai * | source-->| shared | private | 69521444403SRam Pai * | dest | | | 69621444403SRam Pai * | | | | | 69721444403SRam Pai * | v | | | 69821444403SRam Pai * |******************************************** 69921444403SRam Pai * | shared | shared (+) | shared (+) | 70021444403SRam Pai * | | | | 70121444403SRam Pai * |non-shared| shared (+*) | private | 70221444403SRam Pai * ********************************************* 70321444403SRam Pai * (+) the mount is moved to the destination. And is then propagated to all 70421444403SRam Pai * the mounts in the propagation tree of the destination mount. 70521444403SRam Pai * (+*) the mount is moved to the destination. 706b90fa9aeSRam Pai * 707b90fa9aeSRam Pai * if the source mount is a tree, the operations explained above is 708b90fa9aeSRam Pai * applied to each mount in the tree. 709b90fa9aeSRam Pai * Must be called without spinlocks held, since this function can sleep 710b90fa9aeSRam Pai * in allocations. 711b90fa9aeSRam Pai */ 712b90fa9aeSRam Pai static int attach_recursive_mnt(struct vfsmount *source_mnt, 71321444403SRam Pai struct nameidata *nd, struct nameidata *parent_nd) 714b90fa9aeSRam Pai { 715b90fa9aeSRam Pai LIST_HEAD(tree_list); 716b90fa9aeSRam Pai struct vfsmount *dest_mnt = nd->mnt; 717b90fa9aeSRam Pai struct dentry *dest_dentry = nd->dentry; 718b90fa9aeSRam Pai struct vfsmount *child, *p; 719b90fa9aeSRam Pai 720b90fa9aeSRam Pai if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) 721b90fa9aeSRam Pai return -EINVAL; 722b90fa9aeSRam Pai 723b90fa9aeSRam Pai if (IS_MNT_SHARED(dest_mnt)) { 724b90fa9aeSRam Pai for (p = source_mnt; p; p = next_mnt(p, source_mnt)) 725b90fa9aeSRam Pai set_mnt_shared(p); 726b90fa9aeSRam Pai } 727b90fa9aeSRam Pai 728b90fa9aeSRam Pai spin_lock(&vfsmount_lock); 72921444403SRam Pai if (parent_nd) { 73021444403SRam Pai detach_mnt(source_mnt, parent_nd); 73121444403SRam Pai attach_mnt(source_mnt, nd); 73221444403SRam Pai touch_namespace(current->namespace); 73321444403SRam Pai } else { 734b90fa9aeSRam Pai mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); 735b90fa9aeSRam Pai commit_tree(source_mnt); 73621444403SRam Pai } 737b90fa9aeSRam Pai 738b90fa9aeSRam Pai list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { 739b90fa9aeSRam Pai list_del_init(&child->mnt_hash); 740b90fa9aeSRam Pai commit_tree(child); 741b90fa9aeSRam Pai } 742b90fa9aeSRam Pai spin_unlock(&vfsmount_lock); 743b90fa9aeSRam Pai return 0; 744b90fa9aeSRam Pai } 745b90fa9aeSRam Pai 7461da177e4SLinus Torvalds static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) 7471da177e4SLinus Torvalds { 7481da177e4SLinus Torvalds int err; 7491da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & MS_NOUSER) 7501da177e4SLinus Torvalds return -EINVAL; 7511da177e4SLinus Torvalds 7521da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 7531da177e4SLinus Torvalds S_ISDIR(mnt->mnt_root->d_inode->i_mode)) 7541da177e4SLinus Torvalds return -ENOTDIR; 7551da177e4SLinus Torvalds 7561da177e4SLinus Torvalds err = -ENOENT; 7571da177e4SLinus Torvalds down(&nd->dentry->d_inode->i_sem); 7581da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 7591da177e4SLinus Torvalds goto out_unlock; 7601da177e4SLinus Torvalds 7611da177e4SLinus Torvalds err = security_sb_check_sb(mnt, nd); 7621da177e4SLinus Torvalds if (err) 7631da177e4SLinus Torvalds goto out_unlock; 7641da177e4SLinus Torvalds 7651da177e4SLinus Torvalds err = -ENOENT; 766b90fa9aeSRam Pai if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) 76721444403SRam Pai err = attach_recursive_mnt(mnt, nd, NULL); 7681da177e4SLinus Torvalds out_unlock: 7691da177e4SLinus Torvalds up(&nd->dentry->d_inode->i_sem); 7701da177e4SLinus Torvalds if (!err) 7711da177e4SLinus Torvalds security_sb_post_addmount(mnt, nd); 7721da177e4SLinus Torvalds return err; 7731da177e4SLinus Torvalds } 7741da177e4SLinus Torvalds 7751da177e4SLinus Torvalds /* 77607b20889SRam Pai * recursively change the type of the mountpoint. 77707b20889SRam Pai */ 77807b20889SRam Pai static int do_change_type(struct nameidata *nd, int flag) 77907b20889SRam Pai { 78007b20889SRam Pai struct vfsmount *m, *mnt = nd->mnt; 78107b20889SRam Pai int recurse = flag & MS_REC; 78207b20889SRam Pai int type = flag & ~MS_REC; 78307b20889SRam Pai 78407b20889SRam Pai if (nd->dentry != nd->mnt->mnt_root) 78507b20889SRam Pai return -EINVAL; 78607b20889SRam Pai 78707b20889SRam Pai down_write(&namespace_sem); 78807b20889SRam Pai spin_lock(&vfsmount_lock); 78907b20889SRam Pai for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) 79007b20889SRam Pai change_mnt_propagation(m, type); 79107b20889SRam Pai spin_unlock(&vfsmount_lock); 79207b20889SRam Pai up_write(&namespace_sem); 79307b20889SRam Pai return 0; 79407b20889SRam Pai } 79507b20889SRam Pai 79607b20889SRam Pai /* 7971da177e4SLinus Torvalds * do loopback mount. 7981da177e4SLinus Torvalds */ 7991da177e4SLinus Torvalds static int do_loopback(struct nameidata *nd, char *old_name, int recurse) 8001da177e4SLinus Torvalds { 8011da177e4SLinus Torvalds struct nameidata old_nd; 8021da177e4SLinus Torvalds struct vfsmount *mnt = NULL; 8031da177e4SLinus Torvalds int err = mount_is_safe(nd); 8041da177e4SLinus Torvalds if (err) 8051da177e4SLinus Torvalds return err; 8061da177e4SLinus Torvalds if (!old_name || !*old_name) 8071da177e4SLinus Torvalds return -EINVAL; 8081da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 8091da177e4SLinus Torvalds if (err) 8101da177e4SLinus Torvalds return err; 8111da177e4SLinus Torvalds 812390c6843SRam Pai down_write(&namespace_sem); 8131da177e4SLinus Torvalds err = -EINVAL; 814ccd48bc7SAl Viro if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) 815ccd48bc7SAl Viro goto out; 816ccd48bc7SAl Viro 8171da177e4SLinus Torvalds err = -ENOMEM; 8181da177e4SLinus Torvalds if (recurse) 81936341f64SRam Pai mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0); 8201da177e4SLinus Torvalds else 82136341f64SRam Pai mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0); 8221da177e4SLinus Torvalds 823ccd48bc7SAl Viro if (!mnt) 824ccd48bc7SAl Viro goto out; 825ccd48bc7SAl Viro 8261da177e4SLinus Torvalds err = graft_tree(mnt, nd); 8271da177e4SLinus Torvalds if (err) { 82870fbcdf4SRam Pai LIST_HEAD(umount_list); 8291da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 83070fbcdf4SRam Pai umount_tree(mnt, &umount_list); 8311da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 83270fbcdf4SRam Pai release_mounts(&umount_list); 8335b83d2c5SRam Pai } 8341da177e4SLinus Torvalds 835ccd48bc7SAl Viro out: 836390c6843SRam Pai up_write(&namespace_sem); 8371da177e4SLinus Torvalds path_release(&old_nd); 8381da177e4SLinus Torvalds return err; 8391da177e4SLinus Torvalds } 8401da177e4SLinus Torvalds 8411da177e4SLinus Torvalds /* 8421da177e4SLinus Torvalds * change filesystem flags. dir should be a physical root of filesystem. 8431da177e4SLinus Torvalds * If you've mounted a non-root directory somewhere and want to do remount 8441da177e4SLinus Torvalds * on it - tough luck. 8451da177e4SLinus Torvalds */ 8461da177e4SLinus Torvalds static int do_remount(struct nameidata *nd, int flags, int mnt_flags, 8471da177e4SLinus Torvalds void *data) 8481da177e4SLinus Torvalds { 8491da177e4SLinus Torvalds int err; 8501da177e4SLinus Torvalds struct super_block *sb = nd->mnt->mnt_sb; 8511da177e4SLinus Torvalds 8521da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 8531da177e4SLinus Torvalds return -EPERM; 8541da177e4SLinus Torvalds 8551da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 8561da177e4SLinus Torvalds return -EINVAL; 8571da177e4SLinus Torvalds 8581da177e4SLinus Torvalds if (nd->dentry != nd->mnt->mnt_root) 8591da177e4SLinus Torvalds return -EINVAL; 8601da177e4SLinus Torvalds 8611da177e4SLinus Torvalds down_write(&sb->s_umount); 8621da177e4SLinus Torvalds err = do_remount_sb(sb, flags, data, 0); 8631da177e4SLinus Torvalds if (!err) 8641da177e4SLinus Torvalds nd->mnt->mnt_flags = mnt_flags; 8651da177e4SLinus Torvalds up_write(&sb->s_umount); 8661da177e4SLinus Torvalds if (!err) 8671da177e4SLinus Torvalds security_sb_post_remount(nd->mnt, flags, data); 8681da177e4SLinus Torvalds return err; 8691da177e4SLinus Torvalds } 8701da177e4SLinus Torvalds 8711da177e4SLinus Torvalds static int do_move_mount(struct nameidata *nd, char *old_name) 8721da177e4SLinus Torvalds { 8731da177e4SLinus Torvalds struct nameidata old_nd, parent_nd; 8741da177e4SLinus Torvalds struct vfsmount *p; 8751da177e4SLinus Torvalds int err = 0; 8761da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 8771da177e4SLinus Torvalds return -EPERM; 8781da177e4SLinus Torvalds if (!old_name || !*old_name) 8791da177e4SLinus Torvalds return -EINVAL; 8801da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 8811da177e4SLinus Torvalds if (err) 8821da177e4SLinus Torvalds return err; 8831da177e4SLinus Torvalds 884390c6843SRam Pai down_write(&namespace_sem); 8851da177e4SLinus Torvalds while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 8861da177e4SLinus Torvalds ; 8871da177e4SLinus Torvalds err = -EINVAL; 8881da177e4SLinus Torvalds if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) 8891da177e4SLinus Torvalds goto out; 8901da177e4SLinus Torvalds 8911da177e4SLinus Torvalds err = -ENOENT; 8921da177e4SLinus Torvalds down(&nd->dentry->d_inode->i_sem); 8931da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 8941da177e4SLinus Torvalds goto out1; 8951da177e4SLinus Torvalds 8961da177e4SLinus Torvalds if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) 89721444403SRam Pai goto out1; 8981da177e4SLinus Torvalds 8991da177e4SLinus Torvalds err = -EINVAL; 9001da177e4SLinus Torvalds if (old_nd.dentry != old_nd.mnt->mnt_root) 90121444403SRam Pai goto out1; 9021da177e4SLinus Torvalds 9031da177e4SLinus Torvalds if (old_nd.mnt == old_nd.mnt->mnt_parent) 90421444403SRam Pai goto out1; 9051da177e4SLinus Torvalds 9061da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 9071da177e4SLinus Torvalds S_ISDIR(old_nd.dentry->d_inode->i_mode)) 90821444403SRam Pai goto out1; 90921444403SRam Pai /* 91021444403SRam Pai * Don't move a mount residing in a shared parent. 91121444403SRam Pai */ 91221444403SRam Pai if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent)) 91321444403SRam Pai goto out1; 9141da177e4SLinus Torvalds err = -ELOOP; 9151da177e4SLinus Torvalds for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) 9161da177e4SLinus Torvalds if (p == old_nd.mnt) 91721444403SRam Pai goto out1; 9181da177e4SLinus Torvalds 91921444403SRam Pai if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd))) 92021444403SRam Pai goto out1; 9211da177e4SLinus Torvalds 92221444403SRam Pai spin_lock(&vfsmount_lock); 9231da177e4SLinus Torvalds /* if the mount is moved, it should no longer be expire 9241da177e4SLinus Torvalds * automatically */ 92555e700b9SMiklos Szeredi list_del_init(&old_nd.mnt->mnt_expire); 9261da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 9271da177e4SLinus Torvalds out1: 9281da177e4SLinus Torvalds up(&nd->dentry->d_inode->i_sem); 9291da177e4SLinus Torvalds out: 930390c6843SRam Pai up_write(&namespace_sem); 9311da177e4SLinus Torvalds if (!err) 9321da177e4SLinus Torvalds path_release(&parent_nd); 9331da177e4SLinus Torvalds path_release(&old_nd); 9341da177e4SLinus Torvalds return err; 9351da177e4SLinus Torvalds } 9361da177e4SLinus Torvalds 9371da177e4SLinus Torvalds /* 9381da177e4SLinus Torvalds * create a new mount for userspace and request it to be added into the 9391da177e4SLinus Torvalds * namespace's tree 9401da177e4SLinus Torvalds */ 9411da177e4SLinus Torvalds static int do_new_mount(struct nameidata *nd, char *type, int flags, 9421da177e4SLinus Torvalds int mnt_flags, char *name, void *data) 9431da177e4SLinus Torvalds { 9441da177e4SLinus Torvalds struct vfsmount *mnt; 9451da177e4SLinus Torvalds 9461da177e4SLinus Torvalds if (!type || !memchr(type, 0, PAGE_SIZE)) 9471da177e4SLinus Torvalds return -EINVAL; 9481da177e4SLinus Torvalds 9491da177e4SLinus Torvalds /* we need capabilities... */ 9501da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 9511da177e4SLinus Torvalds return -EPERM; 9521da177e4SLinus Torvalds 9531da177e4SLinus Torvalds mnt = do_kern_mount(type, flags, name, data); 9541da177e4SLinus Torvalds if (IS_ERR(mnt)) 9551da177e4SLinus Torvalds return PTR_ERR(mnt); 9561da177e4SLinus Torvalds 9571da177e4SLinus Torvalds return do_add_mount(mnt, nd, mnt_flags, NULL); 9581da177e4SLinus Torvalds } 9591da177e4SLinus Torvalds 9601da177e4SLinus Torvalds /* 9611da177e4SLinus Torvalds * add a mount into a namespace's mount tree 9621da177e4SLinus Torvalds * - provide the option of adding the new mount to an expiration list 9631da177e4SLinus Torvalds */ 9641da177e4SLinus Torvalds int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, 9651da177e4SLinus Torvalds int mnt_flags, struct list_head *fslist) 9661da177e4SLinus Torvalds { 9671da177e4SLinus Torvalds int err; 9681da177e4SLinus Torvalds 969390c6843SRam Pai down_write(&namespace_sem); 9701da177e4SLinus Torvalds /* Something was mounted here while we slept */ 9711da177e4SLinus Torvalds while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 9721da177e4SLinus Torvalds ; 9731da177e4SLinus Torvalds err = -EINVAL; 9741da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 9751da177e4SLinus Torvalds goto unlock; 9761da177e4SLinus Torvalds 9771da177e4SLinus Torvalds /* Refuse the same filesystem on the same mount point */ 9781da177e4SLinus Torvalds err = -EBUSY; 9791da177e4SLinus Torvalds if (nd->mnt->mnt_sb == newmnt->mnt_sb && 9801da177e4SLinus Torvalds nd->mnt->mnt_root == nd->dentry) 9811da177e4SLinus Torvalds goto unlock; 9821da177e4SLinus Torvalds 9831da177e4SLinus Torvalds err = -EINVAL; 9841da177e4SLinus Torvalds if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) 9851da177e4SLinus Torvalds goto unlock; 9861da177e4SLinus Torvalds 9871da177e4SLinus Torvalds newmnt->mnt_flags = mnt_flags; 9885b83d2c5SRam Pai if ((err = graft_tree(newmnt, nd))) 9895b83d2c5SRam Pai goto unlock; 9901da177e4SLinus Torvalds 9915b83d2c5SRam Pai if (fslist) { 9921da177e4SLinus Torvalds /* add to the specified expiration list */ 9931da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 99455e700b9SMiklos Szeredi list_add_tail(&newmnt->mnt_expire, fslist); 9951da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 9961da177e4SLinus Torvalds } 997390c6843SRam Pai up_write(&namespace_sem); 9985b83d2c5SRam Pai return 0; 9991da177e4SLinus Torvalds 10001da177e4SLinus Torvalds unlock: 1001390c6843SRam Pai up_write(&namespace_sem); 10021da177e4SLinus Torvalds mntput(newmnt); 10031da177e4SLinus Torvalds return err; 10041da177e4SLinus Torvalds } 10051da177e4SLinus Torvalds 10061da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(do_add_mount); 10071da177e4SLinus Torvalds 100870fbcdf4SRam Pai static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, 100970fbcdf4SRam Pai struct list_head *umounts) 101024ca2af1SMiklos Szeredi { 101124ca2af1SMiklos Szeredi spin_lock(&vfsmount_lock); 101224ca2af1SMiklos Szeredi 101324ca2af1SMiklos Szeredi /* 1014ed42c879SMiklos Szeredi * Check if mount is still attached, if not, let whoever holds it deal 1015ed42c879SMiklos Szeredi * with the sucker 1016ed42c879SMiklos Szeredi */ 1017ed42c879SMiklos Szeredi if (mnt->mnt_parent == mnt) { 1018ed42c879SMiklos Szeredi spin_unlock(&vfsmount_lock); 1019ed42c879SMiklos Szeredi return; 1020ed42c879SMiklos Szeredi } 1021ed42c879SMiklos Szeredi 1022ed42c879SMiklos Szeredi /* 102324ca2af1SMiklos Szeredi * Check that it is still dead: the count should now be 2 - as 102424ca2af1SMiklos Szeredi * contributed by the vfsmount parent and the mntget above 102524ca2af1SMiklos Szeredi */ 102624ca2af1SMiklos Szeredi if (atomic_read(&mnt->mnt_count) == 2) { 102724ca2af1SMiklos Szeredi /* delete from the namespace */ 10285addc5ddSAl Viro touch_namespace(mnt->mnt_namespace); 102924ca2af1SMiklos Szeredi list_del_init(&mnt->mnt_list); 1030ac081153SMiklos Szeredi mnt->mnt_namespace = NULL; 103170fbcdf4SRam Pai umount_tree(mnt, umounts); 103224ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 103324ca2af1SMiklos Szeredi } else { 103424ca2af1SMiklos Szeredi /* 103524ca2af1SMiklos Szeredi * Someone brought it back to life whilst we didn't have any 103624ca2af1SMiklos Szeredi * locks held so return it to the expiration list 103724ca2af1SMiklos Szeredi */ 103855e700b9SMiklos Szeredi list_add_tail(&mnt->mnt_expire, mounts); 103924ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 104024ca2af1SMiklos Szeredi } 104124ca2af1SMiklos Szeredi } 104224ca2af1SMiklos Szeredi 10431da177e4SLinus Torvalds /* 10441da177e4SLinus Torvalds * process a list of expirable mountpoints with the intent of discarding any 10451da177e4SLinus Torvalds * mountpoints that aren't in use and haven't been touched since last we came 10461da177e4SLinus Torvalds * here 10471da177e4SLinus Torvalds */ 10481da177e4SLinus Torvalds void mark_mounts_for_expiry(struct list_head *mounts) 10491da177e4SLinus Torvalds { 10501da177e4SLinus Torvalds struct namespace *namespace; 10511da177e4SLinus Torvalds struct vfsmount *mnt, *next; 10521da177e4SLinus Torvalds LIST_HEAD(graveyard); 10531da177e4SLinus Torvalds 10541da177e4SLinus Torvalds if (list_empty(mounts)) 10551da177e4SLinus Torvalds return; 10561da177e4SLinus Torvalds 10571da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 10581da177e4SLinus Torvalds 10591da177e4SLinus Torvalds /* extract from the expiration list every vfsmount that matches the 10601da177e4SLinus Torvalds * following criteria: 10611da177e4SLinus Torvalds * - only referenced by its parent vfsmount 10621da177e4SLinus Torvalds * - still marked for expiry (marked on the last call here; marks are 10631da177e4SLinus Torvalds * cleared by mntput()) 10641da177e4SLinus Torvalds */ 106555e700b9SMiklos Szeredi list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { 10661da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1) || 10671da177e4SLinus Torvalds atomic_read(&mnt->mnt_count) != 1) 10681da177e4SLinus Torvalds continue; 10691da177e4SLinus Torvalds 10701da177e4SLinus Torvalds mntget(mnt); 107155e700b9SMiklos Szeredi list_move(&mnt->mnt_expire, &graveyard); 10721da177e4SLinus Torvalds } 10731da177e4SLinus Torvalds 10741da177e4SLinus Torvalds /* 10751da177e4SLinus Torvalds * go through the vfsmounts we've just consigned to the graveyard to 10761da177e4SLinus Torvalds * - check that they're still dead 10771da177e4SLinus Torvalds * - delete the vfsmount from the appropriate namespace under lock 10781da177e4SLinus Torvalds * - dispose of the corpse 10791da177e4SLinus Torvalds */ 10801da177e4SLinus Torvalds while (!list_empty(&graveyard)) { 108170fbcdf4SRam Pai LIST_HEAD(umounts); 108255e700b9SMiklos Szeredi mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire); 108355e700b9SMiklos Szeredi list_del_init(&mnt->mnt_expire); 10841da177e4SLinus Torvalds 10851da177e4SLinus Torvalds /* don't do anything if the namespace is dead - all the 10861da177e4SLinus Torvalds * vfsmounts from it are going away anyway */ 10871da177e4SLinus Torvalds namespace = mnt->mnt_namespace; 10881ce88cf4SMiklos Szeredi if (!namespace || !namespace->root) 10891da177e4SLinus Torvalds continue; 10901da177e4SLinus Torvalds get_namespace(namespace); 10911da177e4SLinus Torvalds 10921da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1093390c6843SRam Pai down_write(&namespace_sem); 109470fbcdf4SRam Pai expire_mount(mnt, mounts, &umounts); 1095390c6843SRam Pai up_write(&namespace_sem); 109670fbcdf4SRam Pai release_mounts(&umounts); 10971da177e4SLinus Torvalds mntput(mnt); 10981da177e4SLinus Torvalds put_namespace(namespace); 10991da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 11001da177e4SLinus Torvalds } 11011da177e4SLinus Torvalds 11021da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 11031da177e4SLinus Torvalds } 11041da177e4SLinus Torvalds 11051da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); 11061da177e4SLinus Torvalds 11071da177e4SLinus Torvalds /* 11081da177e4SLinus Torvalds * Some copy_from_user() implementations do not return the exact number of 11091da177e4SLinus Torvalds * bytes remaining to copy on a fault. But copy_mount_options() requires that. 11101da177e4SLinus Torvalds * Note that this function differs from copy_from_user() in that it will oops 11111da177e4SLinus Torvalds * on bad values of `to', rather than returning a short copy. 11121da177e4SLinus Torvalds */ 1113b58fed8bSRam Pai static long exact_copy_from_user(void *to, const void __user * from, 1114b58fed8bSRam Pai unsigned long n) 11151da177e4SLinus Torvalds { 11161da177e4SLinus Torvalds char *t = to; 11171da177e4SLinus Torvalds const char __user *f = from; 11181da177e4SLinus Torvalds char c; 11191da177e4SLinus Torvalds 11201da177e4SLinus Torvalds if (!access_ok(VERIFY_READ, from, n)) 11211da177e4SLinus Torvalds return n; 11221da177e4SLinus Torvalds 11231da177e4SLinus Torvalds while (n) { 11241da177e4SLinus Torvalds if (__get_user(c, f)) { 11251da177e4SLinus Torvalds memset(t, 0, n); 11261da177e4SLinus Torvalds break; 11271da177e4SLinus Torvalds } 11281da177e4SLinus Torvalds *t++ = c; 11291da177e4SLinus Torvalds f++; 11301da177e4SLinus Torvalds n--; 11311da177e4SLinus Torvalds } 11321da177e4SLinus Torvalds return n; 11331da177e4SLinus Torvalds } 11341da177e4SLinus Torvalds 11351da177e4SLinus Torvalds int copy_mount_options(const void __user * data, unsigned long *where) 11361da177e4SLinus Torvalds { 11371da177e4SLinus Torvalds int i; 11381da177e4SLinus Torvalds unsigned long page; 11391da177e4SLinus Torvalds unsigned long size; 11401da177e4SLinus Torvalds 11411da177e4SLinus Torvalds *where = 0; 11421da177e4SLinus Torvalds if (!data) 11431da177e4SLinus Torvalds return 0; 11441da177e4SLinus Torvalds 11451da177e4SLinus Torvalds if (!(page = __get_free_page(GFP_KERNEL))) 11461da177e4SLinus Torvalds return -ENOMEM; 11471da177e4SLinus Torvalds 11481da177e4SLinus Torvalds /* We only care that *some* data at the address the user 11491da177e4SLinus Torvalds * gave us is valid. Just in case, we'll zero 11501da177e4SLinus Torvalds * the remainder of the page. 11511da177e4SLinus Torvalds */ 11521da177e4SLinus Torvalds /* copy_from_user cannot cross TASK_SIZE ! */ 11531da177e4SLinus Torvalds size = TASK_SIZE - (unsigned long)data; 11541da177e4SLinus Torvalds if (size > PAGE_SIZE) 11551da177e4SLinus Torvalds size = PAGE_SIZE; 11561da177e4SLinus Torvalds 11571da177e4SLinus Torvalds i = size - exact_copy_from_user((void *)page, data, size); 11581da177e4SLinus Torvalds if (!i) { 11591da177e4SLinus Torvalds free_page(page); 11601da177e4SLinus Torvalds return -EFAULT; 11611da177e4SLinus Torvalds } 11621da177e4SLinus Torvalds if (i != PAGE_SIZE) 11631da177e4SLinus Torvalds memset((char *)page + i, 0, PAGE_SIZE - i); 11641da177e4SLinus Torvalds *where = page; 11651da177e4SLinus Torvalds return 0; 11661da177e4SLinus Torvalds } 11671da177e4SLinus Torvalds 11681da177e4SLinus Torvalds /* 11691da177e4SLinus Torvalds * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to 11701da177e4SLinus Torvalds * be given to the mount() call (ie: read-only, no-dev, no-suid etc). 11711da177e4SLinus Torvalds * 11721da177e4SLinus Torvalds * data is a (void *) that can point to any structure up to 11731da177e4SLinus Torvalds * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent 11741da177e4SLinus Torvalds * information (or be NULL). 11751da177e4SLinus Torvalds * 11761da177e4SLinus Torvalds * Pre-0.97 versions of mount() didn't have a flags word. 11771da177e4SLinus Torvalds * When the flags word was introduced its top half was required 11781da177e4SLinus Torvalds * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. 11791da177e4SLinus Torvalds * Therefore, if this magic number is present, it carries no information 11801da177e4SLinus Torvalds * and must be discarded. 11811da177e4SLinus Torvalds */ 11821da177e4SLinus Torvalds long do_mount(char *dev_name, char *dir_name, char *type_page, 11831da177e4SLinus Torvalds unsigned long flags, void *data_page) 11841da177e4SLinus Torvalds { 11851da177e4SLinus Torvalds struct nameidata nd; 11861da177e4SLinus Torvalds int retval = 0; 11871da177e4SLinus Torvalds int mnt_flags = 0; 11881da177e4SLinus Torvalds 11891da177e4SLinus Torvalds /* Discard magic */ 11901da177e4SLinus Torvalds if ((flags & MS_MGC_MSK) == MS_MGC_VAL) 11911da177e4SLinus Torvalds flags &= ~MS_MGC_MSK; 11921da177e4SLinus Torvalds 11931da177e4SLinus Torvalds /* Basic sanity checks */ 11941da177e4SLinus Torvalds 11951da177e4SLinus Torvalds if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) 11961da177e4SLinus Torvalds return -EINVAL; 11971da177e4SLinus Torvalds if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) 11981da177e4SLinus Torvalds return -EINVAL; 11991da177e4SLinus Torvalds 12001da177e4SLinus Torvalds if (data_page) 12011da177e4SLinus Torvalds ((char *)data_page)[PAGE_SIZE - 1] = 0; 12021da177e4SLinus Torvalds 12031da177e4SLinus Torvalds /* Separate the per-mountpoint flags */ 12041da177e4SLinus Torvalds if (flags & MS_NOSUID) 12051da177e4SLinus Torvalds mnt_flags |= MNT_NOSUID; 12061da177e4SLinus Torvalds if (flags & MS_NODEV) 12071da177e4SLinus Torvalds mnt_flags |= MNT_NODEV; 12081da177e4SLinus Torvalds if (flags & MS_NOEXEC) 12091da177e4SLinus Torvalds mnt_flags |= MNT_NOEXEC; 12101da177e4SLinus Torvalds flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE); 12111da177e4SLinus Torvalds 12121da177e4SLinus Torvalds /* ... and get the mountpoint */ 12131da177e4SLinus Torvalds retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); 12141da177e4SLinus Torvalds if (retval) 12151da177e4SLinus Torvalds return retval; 12161da177e4SLinus Torvalds 12171da177e4SLinus Torvalds retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); 12181da177e4SLinus Torvalds if (retval) 12191da177e4SLinus Torvalds goto dput_out; 12201da177e4SLinus Torvalds 12211da177e4SLinus Torvalds if (flags & MS_REMOUNT) 12221da177e4SLinus Torvalds retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, 12231da177e4SLinus Torvalds data_page); 12241da177e4SLinus Torvalds else if (flags & MS_BIND) 12251da177e4SLinus Torvalds retval = do_loopback(&nd, dev_name, flags & MS_REC); 122603e06e68SRam Pai else if (flags & (MS_SHARED | MS_PRIVATE)) 122707b20889SRam Pai retval = do_change_type(&nd, flags); 12281da177e4SLinus Torvalds else if (flags & MS_MOVE) 12291da177e4SLinus Torvalds retval = do_move_mount(&nd, dev_name); 12301da177e4SLinus Torvalds else 12311da177e4SLinus Torvalds retval = do_new_mount(&nd, type_page, flags, mnt_flags, 12321da177e4SLinus Torvalds dev_name, data_page); 12331da177e4SLinus Torvalds dput_out: 12341da177e4SLinus Torvalds path_release(&nd); 12351da177e4SLinus Torvalds return retval; 12361da177e4SLinus Torvalds } 12371da177e4SLinus Torvalds 12381da177e4SLinus Torvalds int copy_namespace(int flags, struct task_struct *tsk) 12391da177e4SLinus Torvalds { 12401da177e4SLinus Torvalds struct namespace *namespace = tsk->namespace; 12411da177e4SLinus Torvalds struct namespace *new_ns; 12421da177e4SLinus Torvalds struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; 12431da177e4SLinus Torvalds struct fs_struct *fs = tsk->fs; 12441da177e4SLinus Torvalds struct vfsmount *p, *q; 12451da177e4SLinus Torvalds 12461da177e4SLinus Torvalds if (!namespace) 12471da177e4SLinus Torvalds return 0; 12481da177e4SLinus Torvalds 12491da177e4SLinus Torvalds get_namespace(namespace); 12501da177e4SLinus Torvalds 12511da177e4SLinus Torvalds if (!(flags & CLONE_NEWNS)) 12521da177e4SLinus Torvalds return 0; 12531da177e4SLinus Torvalds 12541da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) { 12551da177e4SLinus Torvalds put_namespace(namespace); 12561da177e4SLinus Torvalds return -EPERM; 12571da177e4SLinus Torvalds } 12581da177e4SLinus Torvalds 12591da177e4SLinus Torvalds new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL); 12601da177e4SLinus Torvalds if (!new_ns) 12611da177e4SLinus Torvalds goto out; 12621da177e4SLinus Torvalds 12631da177e4SLinus Torvalds atomic_set(&new_ns->count, 1); 12641da177e4SLinus Torvalds INIT_LIST_HEAD(&new_ns->list); 12655addc5ddSAl Viro init_waitqueue_head(&new_ns->poll); 12665addc5ddSAl Viro new_ns->event = 0; 12671da177e4SLinus Torvalds 1268390c6843SRam Pai down_write(&namespace_sem); 12691da177e4SLinus Torvalds /* First pass: copy the tree topology */ 127036341f64SRam Pai new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root, 127136341f64SRam Pai CL_EXPIRE); 12721da177e4SLinus Torvalds if (!new_ns->root) { 1273390c6843SRam Pai up_write(&namespace_sem); 12741da177e4SLinus Torvalds kfree(new_ns); 12751da177e4SLinus Torvalds goto out; 12761da177e4SLinus Torvalds } 12771da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 12781da177e4SLinus Torvalds list_add_tail(&new_ns->list, &new_ns->root->mnt_list); 12791da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 12801da177e4SLinus Torvalds 12811da177e4SLinus Torvalds /* 12821da177e4SLinus Torvalds * Second pass: switch the tsk->fs->* elements and mark new vfsmounts 12831da177e4SLinus Torvalds * as belonging to new namespace. We have already acquired a private 12841da177e4SLinus Torvalds * fs_struct, so tsk->fs->lock is not needed. 12851da177e4SLinus Torvalds */ 12861da177e4SLinus Torvalds p = namespace->root; 12871da177e4SLinus Torvalds q = new_ns->root; 12881da177e4SLinus Torvalds while (p) { 12891da177e4SLinus Torvalds q->mnt_namespace = new_ns; 12901da177e4SLinus Torvalds if (fs) { 12911da177e4SLinus Torvalds if (p == fs->rootmnt) { 12921da177e4SLinus Torvalds rootmnt = p; 12931da177e4SLinus Torvalds fs->rootmnt = mntget(q); 12941da177e4SLinus Torvalds } 12951da177e4SLinus Torvalds if (p == fs->pwdmnt) { 12961da177e4SLinus Torvalds pwdmnt = p; 12971da177e4SLinus Torvalds fs->pwdmnt = mntget(q); 12981da177e4SLinus Torvalds } 12991da177e4SLinus Torvalds if (p == fs->altrootmnt) { 13001da177e4SLinus Torvalds altrootmnt = p; 13011da177e4SLinus Torvalds fs->altrootmnt = mntget(q); 13021da177e4SLinus Torvalds } 13031da177e4SLinus Torvalds } 13041da177e4SLinus Torvalds p = next_mnt(p, namespace->root); 13051da177e4SLinus Torvalds q = next_mnt(q, new_ns->root); 13061da177e4SLinus Torvalds } 1307390c6843SRam Pai up_write(&namespace_sem); 13081da177e4SLinus Torvalds 13091da177e4SLinus Torvalds tsk->namespace = new_ns; 13101da177e4SLinus Torvalds 13111da177e4SLinus Torvalds if (rootmnt) 13121da177e4SLinus Torvalds mntput(rootmnt); 13131da177e4SLinus Torvalds if (pwdmnt) 13141da177e4SLinus Torvalds mntput(pwdmnt); 13151da177e4SLinus Torvalds if (altrootmnt) 13161da177e4SLinus Torvalds mntput(altrootmnt); 13171da177e4SLinus Torvalds 13181da177e4SLinus Torvalds put_namespace(namespace); 13191da177e4SLinus Torvalds return 0; 13201da177e4SLinus Torvalds 13211da177e4SLinus Torvalds out: 13221da177e4SLinus Torvalds put_namespace(namespace); 13231da177e4SLinus Torvalds return -ENOMEM; 13241da177e4SLinus Torvalds } 13251da177e4SLinus Torvalds 13261da177e4SLinus Torvalds asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, 13271da177e4SLinus Torvalds char __user * type, unsigned long flags, 13281da177e4SLinus Torvalds void __user * data) 13291da177e4SLinus Torvalds { 13301da177e4SLinus Torvalds int retval; 13311da177e4SLinus Torvalds unsigned long data_page; 13321da177e4SLinus Torvalds unsigned long type_page; 13331da177e4SLinus Torvalds unsigned long dev_page; 13341da177e4SLinus Torvalds char *dir_page; 13351da177e4SLinus Torvalds 13361da177e4SLinus Torvalds retval = copy_mount_options(type, &type_page); 13371da177e4SLinus Torvalds if (retval < 0) 13381da177e4SLinus Torvalds return retval; 13391da177e4SLinus Torvalds 13401da177e4SLinus Torvalds dir_page = getname(dir_name); 13411da177e4SLinus Torvalds retval = PTR_ERR(dir_page); 13421da177e4SLinus Torvalds if (IS_ERR(dir_page)) 13431da177e4SLinus Torvalds goto out1; 13441da177e4SLinus Torvalds 13451da177e4SLinus Torvalds retval = copy_mount_options(dev_name, &dev_page); 13461da177e4SLinus Torvalds if (retval < 0) 13471da177e4SLinus Torvalds goto out2; 13481da177e4SLinus Torvalds 13491da177e4SLinus Torvalds retval = copy_mount_options(data, &data_page); 13501da177e4SLinus Torvalds if (retval < 0) 13511da177e4SLinus Torvalds goto out3; 13521da177e4SLinus Torvalds 13531da177e4SLinus Torvalds lock_kernel(); 13541da177e4SLinus Torvalds retval = do_mount((char *)dev_page, dir_page, (char *)type_page, 13551da177e4SLinus Torvalds flags, (void *)data_page); 13561da177e4SLinus Torvalds unlock_kernel(); 13571da177e4SLinus Torvalds free_page(data_page); 13581da177e4SLinus Torvalds 13591da177e4SLinus Torvalds out3: 13601da177e4SLinus Torvalds free_page(dev_page); 13611da177e4SLinus Torvalds out2: 13621da177e4SLinus Torvalds putname(dir_page); 13631da177e4SLinus Torvalds out1: 13641da177e4SLinus Torvalds free_page(type_page); 13651da177e4SLinus Torvalds return retval; 13661da177e4SLinus Torvalds } 13671da177e4SLinus Torvalds 13681da177e4SLinus Torvalds /* 13691da177e4SLinus Torvalds * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. 13701da177e4SLinus Torvalds * It can block. Requires the big lock held. 13711da177e4SLinus Torvalds */ 13721da177e4SLinus Torvalds void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, 13731da177e4SLinus Torvalds struct dentry *dentry) 13741da177e4SLinus Torvalds { 13751da177e4SLinus Torvalds struct dentry *old_root; 13761da177e4SLinus Torvalds struct vfsmount *old_rootmnt; 13771da177e4SLinus Torvalds write_lock(&fs->lock); 13781da177e4SLinus Torvalds old_root = fs->root; 13791da177e4SLinus Torvalds old_rootmnt = fs->rootmnt; 13801da177e4SLinus Torvalds fs->rootmnt = mntget(mnt); 13811da177e4SLinus Torvalds fs->root = dget(dentry); 13821da177e4SLinus Torvalds write_unlock(&fs->lock); 13831da177e4SLinus Torvalds if (old_root) { 13841da177e4SLinus Torvalds dput(old_root); 13851da177e4SLinus Torvalds mntput(old_rootmnt); 13861da177e4SLinus Torvalds } 13871da177e4SLinus Torvalds } 13881da177e4SLinus Torvalds 13891da177e4SLinus Torvalds /* 13901da177e4SLinus Torvalds * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. 13911da177e4SLinus Torvalds * It can block. Requires the big lock held. 13921da177e4SLinus Torvalds */ 13931da177e4SLinus Torvalds void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, 13941da177e4SLinus Torvalds struct dentry *dentry) 13951da177e4SLinus Torvalds { 13961da177e4SLinus Torvalds struct dentry *old_pwd; 13971da177e4SLinus Torvalds struct vfsmount *old_pwdmnt; 13981da177e4SLinus Torvalds 13991da177e4SLinus Torvalds write_lock(&fs->lock); 14001da177e4SLinus Torvalds old_pwd = fs->pwd; 14011da177e4SLinus Torvalds old_pwdmnt = fs->pwdmnt; 14021da177e4SLinus Torvalds fs->pwdmnt = mntget(mnt); 14031da177e4SLinus Torvalds fs->pwd = dget(dentry); 14041da177e4SLinus Torvalds write_unlock(&fs->lock); 14051da177e4SLinus Torvalds 14061da177e4SLinus Torvalds if (old_pwd) { 14071da177e4SLinus Torvalds dput(old_pwd); 14081da177e4SLinus Torvalds mntput(old_pwdmnt); 14091da177e4SLinus Torvalds } 14101da177e4SLinus Torvalds } 14111da177e4SLinus Torvalds 14121da177e4SLinus Torvalds static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) 14131da177e4SLinus Torvalds { 14141da177e4SLinus Torvalds struct task_struct *g, *p; 14151da177e4SLinus Torvalds struct fs_struct *fs; 14161da177e4SLinus Torvalds 14171da177e4SLinus Torvalds read_lock(&tasklist_lock); 14181da177e4SLinus Torvalds do_each_thread(g, p) { 14191da177e4SLinus Torvalds task_lock(p); 14201da177e4SLinus Torvalds fs = p->fs; 14211da177e4SLinus Torvalds if (fs) { 14221da177e4SLinus Torvalds atomic_inc(&fs->count); 14231da177e4SLinus Torvalds task_unlock(p); 1424b58fed8bSRam Pai if (fs->root == old_nd->dentry 1425b58fed8bSRam Pai && fs->rootmnt == old_nd->mnt) 14261da177e4SLinus Torvalds set_fs_root(fs, new_nd->mnt, new_nd->dentry); 1427b58fed8bSRam Pai if (fs->pwd == old_nd->dentry 1428b58fed8bSRam Pai && fs->pwdmnt == old_nd->mnt) 14291da177e4SLinus Torvalds set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); 14301da177e4SLinus Torvalds put_fs_struct(fs); 14311da177e4SLinus Torvalds } else 14321da177e4SLinus Torvalds task_unlock(p); 14331da177e4SLinus Torvalds } while_each_thread(g, p); 14341da177e4SLinus Torvalds read_unlock(&tasklist_lock); 14351da177e4SLinus Torvalds } 14361da177e4SLinus Torvalds 14371da177e4SLinus Torvalds /* 14381da177e4SLinus Torvalds * pivot_root Semantics: 14391da177e4SLinus Torvalds * Moves the root file system of the current process to the directory put_old, 14401da177e4SLinus Torvalds * makes new_root as the new root file system of the current process, and sets 14411da177e4SLinus Torvalds * root/cwd of all processes which had them on the current root to new_root. 14421da177e4SLinus Torvalds * 14431da177e4SLinus Torvalds * Restrictions: 14441da177e4SLinus Torvalds * The new_root and put_old must be directories, and must not be on the 14451da177e4SLinus Torvalds * same file system as the current process root. The put_old must be 14461da177e4SLinus Torvalds * underneath new_root, i.e. adding a non-zero number of /.. to the string 14471da177e4SLinus Torvalds * pointed to by put_old must yield the same directory as new_root. No other 14481da177e4SLinus Torvalds * file system may be mounted on put_old. After all, new_root is a mountpoint. 14491da177e4SLinus Torvalds * 14501da177e4SLinus Torvalds * Notes: 14511da177e4SLinus Torvalds * - we don't move root/cwd if they are not at the root (reason: if something 14521da177e4SLinus Torvalds * cared enough to change them, it's probably wrong to force them elsewhere) 14531da177e4SLinus Torvalds * - it's okay to pick a root that isn't the root of a file system, e.g. 14541da177e4SLinus Torvalds * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, 14551da177e4SLinus Torvalds * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root 14561da177e4SLinus Torvalds * first. 14571da177e4SLinus Torvalds */ 1458b58fed8bSRam Pai asmlinkage long sys_pivot_root(const char __user * new_root, 1459b58fed8bSRam Pai const char __user * put_old) 14601da177e4SLinus Torvalds { 14611da177e4SLinus Torvalds struct vfsmount *tmp; 14621da177e4SLinus Torvalds struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; 14631da177e4SLinus Torvalds int error; 14641da177e4SLinus Torvalds 14651da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 14661da177e4SLinus Torvalds return -EPERM; 14671da177e4SLinus Torvalds 14681da177e4SLinus Torvalds lock_kernel(); 14691da177e4SLinus Torvalds 1470b58fed8bSRam Pai error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, 1471b58fed8bSRam Pai &new_nd); 14721da177e4SLinus Torvalds if (error) 14731da177e4SLinus Torvalds goto out0; 14741da177e4SLinus Torvalds error = -EINVAL; 14751da177e4SLinus Torvalds if (!check_mnt(new_nd.mnt)) 14761da177e4SLinus Torvalds goto out1; 14771da177e4SLinus Torvalds 14781da177e4SLinus Torvalds error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd); 14791da177e4SLinus Torvalds if (error) 14801da177e4SLinus Torvalds goto out1; 14811da177e4SLinus Torvalds 14821da177e4SLinus Torvalds error = security_sb_pivotroot(&old_nd, &new_nd); 14831da177e4SLinus Torvalds if (error) { 14841da177e4SLinus Torvalds path_release(&old_nd); 14851da177e4SLinus Torvalds goto out1; 14861da177e4SLinus Torvalds } 14871da177e4SLinus Torvalds 14881da177e4SLinus Torvalds read_lock(¤t->fs->lock); 14891da177e4SLinus Torvalds user_nd.mnt = mntget(current->fs->rootmnt); 14901da177e4SLinus Torvalds user_nd.dentry = dget(current->fs->root); 14911da177e4SLinus Torvalds read_unlock(¤t->fs->lock); 1492390c6843SRam Pai down_write(&namespace_sem); 14931da177e4SLinus Torvalds down(&old_nd.dentry->d_inode->i_sem); 14941da177e4SLinus Torvalds error = -EINVAL; 149521444403SRam Pai if (IS_MNT_SHARED(old_nd.mnt) || 149621444403SRam Pai IS_MNT_SHARED(new_nd.mnt->mnt_parent) || 149721444403SRam Pai IS_MNT_SHARED(user_nd.mnt->mnt_parent)) 149821444403SRam Pai goto out2; 14991da177e4SLinus Torvalds if (!check_mnt(user_nd.mnt)) 15001da177e4SLinus Torvalds goto out2; 15011da177e4SLinus Torvalds error = -ENOENT; 15021da177e4SLinus Torvalds if (IS_DEADDIR(new_nd.dentry->d_inode)) 15031da177e4SLinus Torvalds goto out2; 15041da177e4SLinus Torvalds if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) 15051da177e4SLinus Torvalds goto out2; 15061da177e4SLinus Torvalds if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) 15071da177e4SLinus Torvalds goto out2; 15081da177e4SLinus Torvalds error = -EBUSY; 15091da177e4SLinus Torvalds if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) 15101da177e4SLinus Torvalds goto out2; /* loop, on the same file system */ 15111da177e4SLinus Torvalds error = -EINVAL; 15121da177e4SLinus Torvalds if (user_nd.mnt->mnt_root != user_nd.dentry) 15131da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 15140bb6fcc1SMiklos Szeredi if (user_nd.mnt->mnt_parent == user_nd.mnt) 15150bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 15161da177e4SLinus Torvalds if (new_nd.mnt->mnt_root != new_nd.dentry) 15171da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 15180bb6fcc1SMiklos Szeredi if (new_nd.mnt->mnt_parent == new_nd.mnt) 15190bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 15201da177e4SLinus Torvalds tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ 15211da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 15221da177e4SLinus Torvalds if (tmp != new_nd.mnt) { 15231da177e4SLinus Torvalds for (;;) { 15241da177e4SLinus Torvalds if (tmp->mnt_parent == tmp) 15251da177e4SLinus Torvalds goto out3; /* already mounted on put_old */ 15261da177e4SLinus Torvalds if (tmp->mnt_parent == new_nd.mnt) 15271da177e4SLinus Torvalds break; 15281da177e4SLinus Torvalds tmp = tmp->mnt_parent; 15291da177e4SLinus Torvalds } 15301da177e4SLinus Torvalds if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) 15311da177e4SLinus Torvalds goto out3; 15321da177e4SLinus Torvalds } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) 15331da177e4SLinus Torvalds goto out3; 15341da177e4SLinus Torvalds detach_mnt(new_nd.mnt, &parent_nd); 15351da177e4SLinus Torvalds detach_mnt(user_nd.mnt, &root_parent); 15361da177e4SLinus Torvalds attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ 15371da177e4SLinus Torvalds attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ 15385addc5ddSAl Viro touch_namespace(current->namespace); 15391da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 15401da177e4SLinus Torvalds chroot_fs_refs(&user_nd, &new_nd); 15411da177e4SLinus Torvalds security_sb_post_pivotroot(&user_nd, &new_nd); 15421da177e4SLinus Torvalds error = 0; 15431da177e4SLinus Torvalds path_release(&root_parent); 15441da177e4SLinus Torvalds path_release(&parent_nd); 15451da177e4SLinus Torvalds out2: 15461da177e4SLinus Torvalds up(&old_nd.dentry->d_inode->i_sem); 1547390c6843SRam Pai up_write(&namespace_sem); 15481da177e4SLinus Torvalds path_release(&user_nd); 15491da177e4SLinus Torvalds path_release(&old_nd); 15501da177e4SLinus Torvalds out1: 15511da177e4SLinus Torvalds path_release(&new_nd); 15521da177e4SLinus Torvalds out0: 15531da177e4SLinus Torvalds unlock_kernel(); 15541da177e4SLinus Torvalds return error; 15551da177e4SLinus Torvalds out3: 15561da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 15571da177e4SLinus Torvalds goto out2; 15581da177e4SLinus Torvalds } 15591da177e4SLinus Torvalds 15601da177e4SLinus Torvalds static void __init init_mount_tree(void) 15611da177e4SLinus Torvalds { 15621da177e4SLinus Torvalds struct vfsmount *mnt; 15631da177e4SLinus Torvalds struct namespace *namespace; 15641da177e4SLinus Torvalds struct task_struct *g, *p; 15651da177e4SLinus Torvalds 15661da177e4SLinus Torvalds mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); 15671da177e4SLinus Torvalds if (IS_ERR(mnt)) 15681da177e4SLinus Torvalds panic("Can't create rootfs"); 15691da177e4SLinus Torvalds namespace = kmalloc(sizeof(*namespace), GFP_KERNEL); 15701da177e4SLinus Torvalds if (!namespace) 15711da177e4SLinus Torvalds panic("Can't allocate initial namespace"); 15721da177e4SLinus Torvalds atomic_set(&namespace->count, 1); 15731da177e4SLinus Torvalds INIT_LIST_HEAD(&namespace->list); 15745addc5ddSAl Viro init_waitqueue_head(&namespace->poll); 15755addc5ddSAl Viro namespace->event = 0; 15761da177e4SLinus Torvalds list_add(&mnt->mnt_list, &namespace->list); 15771da177e4SLinus Torvalds namespace->root = mnt; 15781da177e4SLinus Torvalds mnt->mnt_namespace = namespace; 15791da177e4SLinus Torvalds 15801da177e4SLinus Torvalds init_task.namespace = namespace; 15811da177e4SLinus Torvalds read_lock(&tasklist_lock); 15821da177e4SLinus Torvalds do_each_thread(g, p) { 15831da177e4SLinus Torvalds get_namespace(namespace); 15841da177e4SLinus Torvalds p->namespace = namespace; 15851da177e4SLinus Torvalds } while_each_thread(g, p); 15861da177e4SLinus Torvalds read_unlock(&tasklist_lock); 15871da177e4SLinus Torvalds 15881da177e4SLinus Torvalds set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root); 15891da177e4SLinus Torvalds set_fs_root(current->fs, namespace->root, namespace->root->mnt_root); 15901da177e4SLinus Torvalds } 15911da177e4SLinus Torvalds 15921da177e4SLinus Torvalds void __init mnt_init(unsigned long mempages) 15931da177e4SLinus Torvalds { 15941da177e4SLinus Torvalds struct list_head *d; 15951da177e4SLinus Torvalds unsigned int nr_hash; 15961da177e4SLinus Torvalds int i; 15971da177e4SLinus Torvalds 1598390c6843SRam Pai init_rwsem(&namespace_sem); 1599390c6843SRam Pai 16001da177e4SLinus Torvalds mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), 16011da177e4SLinus Torvalds 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL, NULL); 16021da177e4SLinus Torvalds 1603b58fed8bSRam Pai mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); 16041da177e4SLinus Torvalds 16051da177e4SLinus Torvalds if (!mount_hashtable) 16061da177e4SLinus Torvalds panic("Failed to allocate mount hash table\n"); 16071da177e4SLinus Torvalds 16081da177e4SLinus Torvalds /* 16091da177e4SLinus Torvalds * Find the power-of-two list-heads that can fit into the allocation.. 16101da177e4SLinus Torvalds * We don't guarantee that "sizeof(struct list_head)" is necessarily 16111da177e4SLinus Torvalds * a power-of-two. 16121da177e4SLinus Torvalds */ 16131da177e4SLinus Torvalds nr_hash = PAGE_SIZE / sizeof(struct list_head); 16141da177e4SLinus Torvalds hash_bits = 0; 16151da177e4SLinus Torvalds do { 16161da177e4SLinus Torvalds hash_bits++; 16171da177e4SLinus Torvalds } while ((nr_hash >> hash_bits) != 0); 16181da177e4SLinus Torvalds hash_bits--; 16191da177e4SLinus Torvalds 16201da177e4SLinus Torvalds /* 16211da177e4SLinus Torvalds * Re-calculate the actual number of entries and the mask 16221da177e4SLinus Torvalds * from the number of bits we can fit. 16231da177e4SLinus Torvalds */ 16241da177e4SLinus Torvalds nr_hash = 1UL << hash_bits; 16251da177e4SLinus Torvalds hash_mask = nr_hash - 1; 16261da177e4SLinus Torvalds 16271da177e4SLinus Torvalds printk("Mount-cache hash table entries: %d\n", nr_hash); 16281da177e4SLinus Torvalds 16291da177e4SLinus Torvalds /* And initialize the newly allocated array */ 16301da177e4SLinus Torvalds d = mount_hashtable; 16311da177e4SLinus Torvalds i = nr_hash; 16321da177e4SLinus Torvalds do { 16331da177e4SLinus Torvalds INIT_LIST_HEAD(d); 16341da177e4SLinus Torvalds d++; 16351da177e4SLinus Torvalds i--; 16361da177e4SLinus Torvalds } while (i); 16371da177e4SLinus Torvalds sysfs_init(); 16381da177e4SLinus Torvalds init_rootfs(); 16391da177e4SLinus Torvalds init_mount_tree(); 16401da177e4SLinus Torvalds } 16411da177e4SLinus Torvalds 16421da177e4SLinus Torvalds void __put_namespace(struct namespace *namespace) 16431da177e4SLinus Torvalds { 16441ce88cf4SMiklos Szeredi struct vfsmount *root = namespace->root; 164570fbcdf4SRam Pai LIST_HEAD(umount_list); 16461ce88cf4SMiklos Szeredi namespace->root = NULL; 16471ce88cf4SMiklos Szeredi spin_unlock(&vfsmount_lock); 1648390c6843SRam Pai down_write(&namespace_sem); 16491da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 165070fbcdf4SRam Pai umount_tree(root, &umount_list); 16511da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1652390c6843SRam Pai up_write(&namespace_sem); 165370fbcdf4SRam Pai release_mounts(&umount_list); 16541da177e4SLinus Torvalds kfree(namespace); 16551da177e4SLinus Torvalds } 1656