11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namespace.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * (C) Copyright Al Viro 2000, 2001 51da177e4SLinus Torvalds * Released under GPL v2. 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Based on code from fs/super.c, copyright Linus Torvalds and others. 81da177e4SLinus Torvalds * Heavily rewritten. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds #include <linux/config.h> 121da177e4SLinus Torvalds #include <linux/syscalls.h> 131da177e4SLinus Torvalds #include <linux/slab.h> 141da177e4SLinus Torvalds #include <linux/sched.h> 151da177e4SLinus Torvalds #include <linux/smp_lock.h> 161da177e4SLinus Torvalds #include <linux/init.h> 171da177e4SLinus Torvalds #include <linux/quotaops.h> 181da177e4SLinus Torvalds #include <linux/acct.h> 191da177e4SLinus Torvalds #include <linux/module.h> 201da177e4SLinus Torvalds #include <linux/seq_file.h> 211da177e4SLinus Torvalds #include <linux/namespace.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/security.h> 241da177e4SLinus Torvalds #include <linux/mount.h> 251da177e4SLinus Torvalds #include <asm/uaccess.h> 261da177e4SLinus Torvalds #include <asm/unistd.h> 271da177e4SLinus Torvalds 281da177e4SLinus Torvalds extern int __init init_rootfs(void); 291da177e4SLinus Torvalds 301da177e4SLinus Torvalds #ifdef CONFIG_SYSFS 311da177e4SLinus Torvalds extern int __init sysfs_init(void); 321da177e4SLinus Torvalds #else 331da177e4SLinus Torvalds static inline int sysfs_init(void) 341da177e4SLinus Torvalds { 351da177e4SLinus Torvalds return 0; 361da177e4SLinus Torvalds } 371da177e4SLinus Torvalds #endif 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds /* spinlock for vfsmount related operations, inplace of dcache_lock */ 401da177e4SLinus Torvalds __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); 411da177e4SLinus Torvalds 421da177e4SLinus Torvalds static struct list_head *mount_hashtable; 436c231b7bSRavikiran G Thirumalai static int hash_mask __read_mostly, hash_bits __read_mostly; 441da177e4SLinus Torvalds static kmem_cache_t *mnt_cache; 451da177e4SLinus Torvalds 461da177e4SLinus Torvalds static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) 471da177e4SLinus Torvalds { 481da177e4SLinus Torvalds unsigned long tmp = ((unsigned long) mnt / L1_CACHE_BYTES); 491da177e4SLinus Torvalds tmp += ((unsigned long) dentry / L1_CACHE_BYTES); 501da177e4SLinus Torvalds tmp = tmp + (tmp >> hash_bits); 511da177e4SLinus Torvalds return tmp & hash_mask; 521da177e4SLinus Torvalds } 531da177e4SLinus Torvalds 541da177e4SLinus Torvalds struct vfsmount *alloc_vfsmnt(const char *name) 551da177e4SLinus Torvalds { 561da177e4SLinus Torvalds struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL); 571da177e4SLinus Torvalds if (mnt) { 581da177e4SLinus Torvalds memset(mnt, 0, sizeof(struct vfsmount)); 591da177e4SLinus Torvalds atomic_set(&mnt->mnt_count,1); 601da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_hash); 611da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_child); 621da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_mounts); 631da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_list); 6455e700b9SMiklos Szeredi INIT_LIST_HEAD(&mnt->mnt_expire); 651da177e4SLinus Torvalds if (name) { 661da177e4SLinus Torvalds int size = strlen(name)+1; 671da177e4SLinus Torvalds char *newname = kmalloc(size, GFP_KERNEL); 681da177e4SLinus Torvalds if (newname) { 691da177e4SLinus Torvalds memcpy(newname, name, size); 701da177e4SLinus Torvalds mnt->mnt_devname = newname; 711da177e4SLinus Torvalds } 721da177e4SLinus Torvalds } 731da177e4SLinus Torvalds } 741da177e4SLinus Torvalds return mnt; 751da177e4SLinus Torvalds } 761da177e4SLinus Torvalds 771da177e4SLinus Torvalds void free_vfsmnt(struct vfsmount *mnt) 781da177e4SLinus Torvalds { 791da177e4SLinus Torvalds kfree(mnt->mnt_devname); 801da177e4SLinus Torvalds kmem_cache_free(mnt_cache, mnt); 811da177e4SLinus Torvalds } 821da177e4SLinus Torvalds 831da177e4SLinus Torvalds /* 841da177e4SLinus Torvalds * Now, lookup_mnt increments the ref count before returning 851da177e4SLinus Torvalds * the vfsmount struct. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) 881da177e4SLinus Torvalds { 891da177e4SLinus Torvalds struct list_head * head = mount_hashtable + hash(mnt, dentry); 901da177e4SLinus Torvalds struct list_head * tmp = head; 911da177e4SLinus Torvalds struct vfsmount *p, *found = NULL; 921da177e4SLinus Torvalds 931da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 941da177e4SLinus Torvalds for (;;) { 951da177e4SLinus Torvalds tmp = tmp->next; 961da177e4SLinus Torvalds p = NULL; 971da177e4SLinus Torvalds if (tmp == head) 981da177e4SLinus Torvalds break; 991da177e4SLinus Torvalds p = list_entry(tmp, struct vfsmount, mnt_hash); 1001da177e4SLinus Torvalds if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { 1011da177e4SLinus Torvalds found = mntget(p); 1021da177e4SLinus Torvalds break; 1031da177e4SLinus Torvalds } 1041da177e4SLinus Torvalds } 1051da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1061da177e4SLinus Torvalds return found; 1071da177e4SLinus Torvalds } 1081da177e4SLinus Torvalds 1091da177e4SLinus Torvalds static inline int check_mnt(struct vfsmount *mnt) 1101da177e4SLinus Torvalds { 1111da177e4SLinus Torvalds return mnt->mnt_namespace == current->namespace; 1121da177e4SLinus Torvalds } 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) 1151da177e4SLinus Torvalds { 1161da177e4SLinus Torvalds old_nd->dentry = mnt->mnt_mountpoint; 1171da177e4SLinus Torvalds old_nd->mnt = mnt->mnt_parent; 1181da177e4SLinus Torvalds mnt->mnt_parent = mnt; 1191da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 1201da177e4SLinus Torvalds list_del_init(&mnt->mnt_child); 1211da177e4SLinus Torvalds list_del_init(&mnt->mnt_hash); 1221da177e4SLinus Torvalds old_nd->dentry->d_mounted--; 1231da177e4SLinus Torvalds } 1241da177e4SLinus Torvalds 1251da177e4SLinus Torvalds static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) 1261da177e4SLinus Torvalds { 1271da177e4SLinus Torvalds mnt->mnt_parent = mntget(nd->mnt); 1281da177e4SLinus Torvalds mnt->mnt_mountpoint = dget(nd->dentry); 1291da177e4SLinus Torvalds list_add(&mnt->mnt_hash, mount_hashtable+hash(nd->mnt, nd->dentry)); 1301da177e4SLinus Torvalds list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); 1311da177e4SLinus Torvalds nd->dentry->d_mounted++; 1321da177e4SLinus Torvalds } 1331da177e4SLinus Torvalds 1341da177e4SLinus Torvalds static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) 1351da177e4SLinus Torvalds { 1361da177e4SLinus Torvalds struct list_head *next = p->mnt_mounts.next; 1371da177e4SLinus Torvalds if (next == &p->mnt_mounts) { 1381da177e4SLinus Torvalds while (1) { 1391da177e4SLinus Torvalds if (p == root) 1401da177e4SLinus Torvalds return NULL; 1411da177e4SLinus Torvalds next = p->mnt_child.next; 1421da177e4SLinus Torvalds if (next != &p->mnt_parent->mnt_mounts) 1431da177e4SLinus Torvalds break; 1441da177e4SLinus Torvalds p = p->mnt_parent; 1451da177e4SLinus Torvalds } 1461da177e4SLinus Torvalds } 1471da177e4SLinus Torvalds return list_entry(next, struct vfsmount, mnt_child); 1481da177e4SLinus Torvalds } 1491da177e4SLinus Torvalds 1501da177e4SLinus Torvalds static struct vfsmount * 1511da177e4SLinus Torvalds clone_mnt(struct vfsmount *old, struct dentry *root) 1521da177e4SLinus Torvalds { 1531da177e4SLinus Torvalds struct super_block *sb = old->mnt_sb; 1541da177e4SLinus Torvalds struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); 1551da177e4SLinus Torvalds 1561da177e4SLinus Torvalds if (mnt) { 1571da177e4SLinus Torvalds mnt->mnt_flags = old->mnt_flags; 1581da177e4SLinus Torvalds atomic_inc(&sb->s_active); 1591da177e4SLinus Torvalds mnt->mnt_sb = sb; 1601da177e4SLinus Torvalds mnt->mnt_root = dget(root); 1611da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 1621da177e4SLinus Torvalds mnt->mnt_parent = mnt; 16368b47139SMiklos Szeredi mnt->mnt_namespace = current->namespace; 1641da177e4SLinus Torvalds 1651da177e4SLinus Torvalds /* stick the duplicate mount on the same expiry list 1661da177e4SLinus Torvalds * as the original if that was on one */ 1671da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 16855e700b9SMiklos Szeredi if (!list_empty(&old->mnt_expire)) 16955e700b9SMiklos Szeredi list_add(&mnt->mnt_expire, &old->mnt_expire); 1701da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1711da177e4SLinus Torvalds } 1721da177e4SLinus Torvalds return mnt; 1731da177e4SLinus Torvalds } 1741da177e4SLinus Torvalds 175*7b7b1aceSAl Viro static inline void __mntput(struct vfsmount *mnt) 1761da177e4SLinus Torvalds { 1771da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 1781da177e4SLinus Torvalds dput(mnt->mnt_root); 1791da177e4SLinus Torvalds free_vfsmnt(mnt); 1801da177e4SLinus Torvalds deactivate_super(sb); 1811da177e4SLinus Torvalds } 1821da177e4SLinus Torvalds 183*7b7b1aceSAl Viro void mntput_no_expire(struct vfsmount *mnt) 184*7b7b1aceSAl Viro { 185*7b7b1aceSAl Viro repeat: 186*7b7b1aceSAl Viro if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { 187*7b7b1aceSAl Viro if (likely(!mnt->mnt_pinned)) { 188*7b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 189*7b7b1aceSAl Viro __mntput(mnt); 190*7b7b1aceSAl Viro return; 191*7b7b1aceSAl Viro } 192*7b7b1aceSAl Viro atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); 193*7b7b1aceSAl Viro mnt->mnt_pinned = 0; 194*7b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 195*7b7b1aceSAl Viro acct_auto_close_mnt(mnt); 196*7b7b1aceSAl Viro security_sb_umount_close(mnt); 197*7b7b1aceSAl Viro goto repeat; 198*7b7b1aceSAl Viro } 199*7b7b1aceSAl Viro } 200*7b7b1aceSAl Viro 201*7b7b1aceSAl Viro EXPORT_SYMBOL(mntput_no_expire); 202*7b7b1aceSAl Viro 203*7b7b1aceSAl Viro void mnt_pin(struct vfsmount *mnt) 204*7b7b1aceSAl Viro { 205*7b7b1aceSAl Viro spin_lock(&vfsmount_lock); 206*7b7b1aceSAl Viro mnt->mnt_pinned++; 207*7b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 208*7b7b1aceSAl Viro } 209*7b7b1aceSAl Viro 210*7b7b1aceSAl Viro EXPORT_SYMBOL(mnt_pin); 211*7b7b1aceSAl Viro 212*7b7b1aceSAl Viro void mnt_unpin(struct vfsmount *mnt) 213*7b7b1aceSAl Viro { 214*7b7b1aceSAl Viro spin_lock(&vfsmount_lock); 215*7b7b1aceSAl Viro if (mnt->mnt_pinned) { 216*7b7b1aceSAl Viro atomic_inc(&mnt->mnt_count); 217*7b7b1aceSAl Viro mnt->mnt_pinned--; 218*7b7b1aceSAl Viro } 219*7b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 220*7b7b1aceSAl Viro } 221*7b7b1aceSAl Viro 222*7b7b1aceSAl Viro EXPORT_SYMBOL(mnt_unpin); 2231da177e4SLinus Torvalds 2241da177e4SLinus Torvalds /* iterator */ 2251da177e4SLinus Torvalds static void *m_start(struct seq_file *m, loff_t *pos) 2261da177e4SLinus Torvalds { 2271da177e4SLinus Torvalds struct namespace *n = m->private; 2281da177e4SLinus Torvalds struct list_head *p; 2291da177e4SLinus Torvalds loff_t l = *pos; 2301da177e4SLinus Torvalds 2311da177e4SLinus Torvalds down_read(&n->sem); 2321da177e4SLinus Torvalds list_for_each(p, &n->list) 2331da177e4SLinus Torvalds if (!l--) 2341da177e4SLinus Torvalds return list_entry(p, struct vfsmount, mnt_list); 2351da177e4SLinus Torvalds return NULL; 2361da177e4SLinus Torvalds } 2371da177e4SLinus Torvalds 2381da177e4SLinus Torvalds static void *m_next(struct seq_file *m, void *v, loff_t *pos) 2391da177e4SLinus Torvalds { 2401da177e4SLinus Torvalds struct namespace *n = m->private; 2411da177e4SLinus Torvalds struct list_head *p = ((struct vfsmount *)v)->mnt_list.next; 2421da177e4SLinus Torvalds (*pos)++; 2431da177e4SLinus Torvalds return p==&n->list ? NULL : list_entry(p, struct vfsmount, mnt_list); 2441da177e4SLinus Torvalds } 2451da177e4SLinus Torvalds 2461da177e4SLinus Torvalds static void m_stop(struct seq_file *m, void *v) 2471da177e4SLinus Torvalds { 2481da177e4SLinus Torvalds struct namespace *n = m->private; 2491da177e4SLinus Torvalds up_read(&n->sem); 2501da177e4SLinus Torvalds } 2511da177e4SLinus Torvalds 2521da177e4SLinus Torvalds static inline void mangle(struct seq_file *m, const char *s) 2531da177e4SLinus Torvalds { 2541da177e4SLinus Torvalds seq_escape(m, s, " \t\n\\"); 2551da177e4SLinus Torvalds } 2561da177e4SLinus Torvalds 2571da177e4SLinus Torvalds static int show_vfsmnt(struct seq_file *m, void *v) 2581da177e4SLinus Torvalds { 2591da177e4SLinus Torvalds struct vfsmount *mnt = v; 2601da177e4SLinus Torvalds int err = 0; 2611da177e4SLinus Torvalds static struct proc_fs_info { 2621da177e4SLinus Torvalds int flag; 2631da177e4SLinus Torvalds char *str; 2641da177e4SLinus Torvalds } fs_info[] = { 2651da177e4SLinus Torvalds { MS_SYNCHRONOUS, ",sync" }, 2661da177e4SLinus Torvalds { MS_DIRSYNC, ",dirsync" }, 2671da177e4SLinus Torvalds { MS_MANDLOCK, ",mand" }, 2681da177e4SLinus Torvalds { MS_NOATIME, ",noatime" }, 2691da177e4SLinus Torvalds { MS_NODIRATIME, ",nodiratime" }, 2701da177e4SLinus Torvalds { 0, NULL } 2711da177e4SLinus Torvalds }; 2721da177e4SLinus Torvalds static struct proc_fs_info mnt_info[] = { 2731da177e4SLinus Torvalds { MNT_NOSUID, ",nosuid" }, 2741da177e4SLinus Torvalds { MNT_NODEV, ",nodev" }, 2751da177e4SLinus Torvalds { MNT_NOEXEC, ",noexec" }, 2761da177e4SLinus Torvalds { 0, NULL } 2771da177e4SLinus Torvalds }; 2781da177e4SLinus Torvalds struct proc_fs_info *fs_infop; 2791da177e4SLinus Torvalds 2801da177e4SLinus Torvalds mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); 2811da177e4SLinus Torvalds seq_putc(m, ' '); 2821da177e4SLinus Torvalds seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); 2831da177e4SLinus Torvalds seq_putc(m, ' '); 2841da177e4SLinus Torvalds mangle(m, mnt->mnt_sb->s_type->name); 2851da177e4SLinus Torvalds seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); 2861da177e4SLinus Torvalds for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { 2871da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & fs_infop->flag) 2881da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 2891da177e4SLinus Torvalds } 2901da177e4SLinus Torvalds for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { 2911da177e4SLinus Torvalds if (mnt->mnt_flags & fs_infop->flag) 2921da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 2931da177e4SLinus Torvalds } 2941da177e4SLinus Torvalds if (mnt->mnt_sb->s_op->show_options) 2951da177e4SLinus Torvalds err = mnt->mnt_sb->s_op->show_options(m, mnt); 2961da177e4SLinus Torvalds seq_puts(m, " 0 0\n"); 2971da177e4SLinus Torvalds return err; 2981da177e4SLinus Torvalds } 2991da177e4SLinus Torvalds 3001da177e4SLinus Torvalds struct seq_operations mounts_op = { 3011da177e4SLinus Torvalds .start = m_start, 3021da177e4SLinus Torvalds .next = m_next, 3031da177e4SLinus Torvalds .stop = m_stop, 3041da177e4SLinus Torvalds .show = show_vfsmnt 3051da177e4SLinus Torvalds }; 3061da177e4SLinus Torvalds 3071da177e4SLinus Torvalds /** 3081da177e4SLinus Torvalds * may_umount_tree - check if a mount tree is busy 3091da177e4SLinus Torvalds * @mnt: root of mount tree 3101da177e4SLinus Torvalds * 3111da177e4SLinus Torvalds * This is called to check if a tree of mounts has any 3121da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts that are 3131da177e4SLinus Torvalds * busy. 3141da177e4SLinus Torvalds */ 3151da177e4SLinus Torvalds int may_umount_tree(struct vfsmount *mnt) 3161da177e4SLinus Torvalds { 3171da177e4SLinus Torvalds struct list_head *next; 3181da177e4SLinus Torvalds struct vfsmount *this_parent = mnt; 3191da177e4SLinus Torvalds int actual_refs; 3201da177e4SLinus Torvalds int minimum_refs; 3211da177e4SLinus Torvalds 3221da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 3231da177e4SLinus Torvalds actual_refs = atomic_read(&mnt->mnt_count); 3241da177e4SLinus Torvalds minimum_refs = 2; 3251da177e4SLinus Torvalds repeat: 3261da177e4SLinus Torvalds next = this_parent->mnt_mounts.next; 3271da177e4SLinus Torvalds resume: 3281da177e4SLinus Torvalds while (next != &this_parent->mnt_mounts) { 3291da177e4SLinus Torvalds struct vfsmount *p = list_entry(next, struct vfsmount, mnt_child); 3301da177e4SLinus Torvalds 3311da177e4SLinus Torvalds next = next->next; 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds actual_refs += atomic_read(&p->mnt_count); 3341da177e4SLinus Torvalds minimum_refs += 2; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds if (!list_empty(&p->mnt_mounts)) { 3371da177e4SLinus Torvalds this_parent = p; 3381da177e4SLinus Torvalds goto repeat; 3391da177e4SLinus Torvalds } 3401da177e4SLinus Torvalds } 3411da177e4SLinus Torvalds 3421da177e4SLinus Torvalds if (this_parent != mnt) { 3431da177e4SLinus Torvalds next = this_parent->mnt_child.next; 3441da177e4SLinus Torvalds this_parent = this_parent->mnt_parent; 3451da177e4SLinus Torvalds goto resume; 3461da177e4SLinus Torvalds } 3471da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds if (actual_refs > minimum_refs) 3501da177e4SLinus Torvalds return -EBUSY; 3511da177e4SLinus Torvalds 3521da177e4SLinus Torvalds return 0; 3531da177e4SLinus Torvalds } 3541da177e4SLinus Torvalds 3551da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount_tree); 3561da177e4SLinus Torvalds 3571da177e4SLinus Torvalds /** 3581da177e4SLinus Torvalds * may_umount - check if a mount point is busy 3591da177e4SLinus Torvalds * @mnt: root of mount 3601da177e4SLinus Torvalds * 3611da177e4SLinus Torvalds * This is called to check if a mount point has any 3621da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts. If the 3631da177e4SLinus Torvalds * mount has sub mounts this will return busy 3641da177e4SLinus Torvalds * regardless of whether the sub mounts are busy. 3651da177e4SLinus Torvalds * 3661da177e4SLinus Torvalds * Doesn't take quota and stuff into account. IOW, in some cases it will 3671da177e4SLinus Torvalds * give false negatives. The main reason why it's here is that we need 3681da177e4SLinus Torvalds * a non-destructive way to look for easily umountable filesystems. 3691da177e4SLinus Torvalds */ 3701da177e4SLinus Torvalds int may_umount(struct vfsmount *mnt) 3711da177e4SLinus Torvalds { 3721da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) > 2) 3731da177e4SLinus Torvalds return -EBUSY; 3741da177e4SLinus Torvalds return 0; 3751da177e4SLinus Torvalds } 3761da177e4SLinus Torvalds 3771da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount); 3781da177e4SLinus Torvalds 37952c1da39SAdrian Bunk static void umount_tree(struct vfsmount *mnt) 3801da177e4SLinus Torvalds { 3811da177e4SLinus Torvalds struct vfsmount *p; 3821da177e4SLinus Torvalds LIST_HEAD(kill); 3831da177e4SLinus Torvalds 3841da177e4SLinus Torvalds for (p = mnt; p; p = next_mnt(p, mnt)) { 3851da177e4SLinus Torvalds list_del(&p->mnt_list); 3861da177e4SLinus Torvalds list_add(&p->mnt_list, &kill); 387202322e6SMiklos Szeredi p->mnt_namespace = NULL; 3881da177e4SLinus Torvalds } 3891da177e4SLinus Torvalds 3901da177e4SLinus Torvalds while (!list_empty(&kill)) { 3911da177e4SLinus Torvalds mnt = list_entry(kill.next, struct vfsmount, mnt_list); 3921da177e4SLinus Torvalds list_del_init(&mnt->mnt_list); 39355e700b9SMiklos Szeredi list_del_init(&mnt->mnt_expire); 3941da177e4SLinus Torvalds if (mnt->mnt_parent == mnt) { 3951da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 3961da177e4SLinus Torvalds } else { 3971da177e4SLinus Torvalds struct nameidata old_nd; 3981da177e4SLinus Torvalds detach_mnt(mnt, &old_nd); 3991da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 4001da177e4SLinus Torvalds path_release(&old_nd); 4011da177e4SLinus Torvalds } 4021da177e4SLinus Torvalds mntput(mnt); 4031da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 4041da177e4SLinus Torvalds } 4051da177e4SLinus Torvalds } 4061da177e4SLinus Torvalds 4071da177e4SLinus Torvalds static int do_umount(struct vfsmount *mnt, int flags) 4081da177e4SLinus Torvalds { 4091da177e4SLinus Torvalds struct super_block * sb = mnt->mnt_sb; 4101da177e4SLinus Torvalds int retval; 4111da177e4SLinus Torvalds 4121da177e4SLinus Torvalds retval = security_sb_umount(mnt, flags); 4131da177e4SLinus Torvalds if (retval) 4141da177e4SLinus Torvalds return retval; 4151da177e4SLinus Torvalds 4161da177e4SLinus Torvalds /* 4171da177e4SLinus Torvalds * Allow userspace to request a mountpoint be expired rather than 4181da177e4SLinus Torvalds * unmounting unconditionally. Unmount only happens if: 4191da177e4SLinus Torvalds * (1) the mark is already set (the mark is cleared by mntput()) 4201da177e4SLinus Torvalds * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] 4211da177e4SLinus Torvalds */ 4221da177e4SLinus Torvalds if (flags & MNT_EXPIRE) { 4231da177e4SLinus Torvalds if (mnt == current->fs->rootmnt || 4241da177e4SLinus Torvalds flags & (MNT_FORCE | MNT_DETACH)) 4251da177e4SLinus Torvalds return -EINVAL; 4261da177e4SLinus Torvalds 4271da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) != 2) 4281da177e4SLinus Torvalds return -EBUSY; 4291da177e4SLinus Torvalds 4301da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1)) 4311da177e4SLinus Torvalds return -EAGAIN; 4321da177e4SLinus Torvalds } 4331da177e4SLinus Torvalds 4341da177e4SLinus Torvalds /* 4351da177e4SLinus Torvalds * If we may have to abort operations to get out of this 4361da177e4SLinus Torvalds * mount, and they will themselves hold resources we must 4371da177e4SLinus Torvalds * allow the fs to do things. In the Unix tradition of 4381da177e4SLinus Torvalds * 'Gee thats tricky lets do it in userspace' the umount_begin 4391da177e4SLinus Torvalds * might fail to complete on the first run through as other tasks 4401da177e4SLinus Torvalds * must return, and the like. Thats for the mount program to worry 4411da177e4SLinus Torvalds * about for the moment. 4421da177e4SLinus Torvalds */ 4431da177e4SLinus Torvalds 4441da177e4SLinus Torvalds lock_kernel(); 4451da177e4SLinus Torvalds if( (flags&MNT_FORCE) && sb->s_op->umount_begin) 4461da177e4SLinus Torvalds sb->s_op->umount_begin(sb); 4471da177e4SLinus Torvalds unlock_kernel(); 4481da177e4SLinus Torvalds 4491da177e4SLinus Torvalds /* 4501da177e4SLinus Torvalds * No sense to grab the lock for this test, but test itself looks 4511da177e4SLinus Torvalds * somewhat bogus. Suggestions for better replacement? 4521da177e4SLinus Torvalds * Ho-hum... In principle, we might treat that as umount + switch 4531da177e4SLinus Torvalds * to rootfs. GC would eventually take care of the old vfsmount. 4541da177e4SLinus Torvalds * Actually it makes sense, especially if rootfs would contain a 4551da177e4SLinus Torvalds * /reboot - static binary that would close all descriptors and 4561da177e4SLinus Torvalds * call reboot(9). Then init(8) could umount root and exec /reboot. 4571da177e4SLinus Torvalds */ 4581da177e4SLinus Torvalds if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { 4591da177e4SLinus Torvalds /* 4601da177e4SLinus Torvalds * Special case for "unmounting" root ... 4611da177e4SLinus Torvalds * we just try to remount it readonly. 4621da177e4SLinus Torvalds */ 4631da177e4SLinus Torvalds down_write(&sb->s_umount); 4641da177e4SLinus Torvalds if (!(sb->s_flags & MS_RDONLY)) { 4651da177e4SLinus Torvalds lock_kernel(); 4661da177e4SLinus Torvalds DQUOT_OFF(sb); 4671da177e4SLinus Torvalds retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); 4681da177e4SLinus Torvalds unlock_kernel(); 4691da177e4SLinus Torvalds } 4701da177e4SLinus Torvalds up_write(&sb->s_umount); 4711da177e4SLinus Torvalds return retval; 4721da177e4SLinus Torvalds } 4731da177e4SLinus Torvalds 4741da177e4SLinus Torvalds down_write(¤t->namespace->sem); 4751da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 4761da177e4SLinus Torvalds 4771da177e4SLinus Torvalds retval = -EBUSY; 4781da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) { 4791da177e4SLinus Torvalds if (!list_empty(&mnt->mnt_list)) 4801da177e4SLinus Torvalds umount_tree(mnt); 4811da177e4SLinus Torvalds retval = 0; 4821da177e4SLinus Torvalds } 4831da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 4841da177e4SLinus Torvalds if (retval) 4851da177e4SLinus Torvalds security_sb_umount_busy(mnt); 4861da177e4SLinus Torvalds up_write(¤t->namespace->sem); 4871da177e4SLinus Torvalds return retval; 4881da177e4SLinus Torvalds } 4891da177e4SLinus Torvalds 4901da177e4SLinus Torvalds /* 4911da177e4SLinus Torvalds * Now umount can handle mount points as well as block devices. 4921da177e4SLinus Torvalds * This is important for filesystems which use unnamed block devices. 4931da177e4SLinus Torvalds * 4941da177e4SLinus Torvalds * We now support a flag for forced unmount like the other 'big iron' 4951da177e4SLinus Torvalds * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD 4961da177e4SLinus Torvalds */ 4971da177e4SLinus Torvalds 4981da177e4SLinus Torvalds asmlinkage long sys_umount(char __user * name, int flags) 4991da177e4SLinus Torvalds { 5001da177e4SLinus Torvalds struct nameidata nd; 5011da177e4SLinus Torvalds int retval; 5021da177e4SLinus Torvalds 5031da177e4SLinus Torvalds retval = __user_walk(name, LOOKUP_FOLLOW, &nd); 5041da177e4SLinus Torvalds if (retval) 5051da177e4SLinus Torvalds goto out; 5061da177e4SLinus Torvalds retval = -EINVAL; 5071da177e4SLinus Torvalds if (nd.dentry != nd.mnt->mnt_root) 5081da177e4SLinus Torvalds goto dput_and_out; 5091da177e4SLinus Torvalds if (!check_mnt(nd.mnt)) 5101da177e4SLinus Torvalds goto dput_and_out; 5111da177e4SLinus Torvalds 5121da177e4SLinus Torvalds retval = -EPERM; 5131da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 5141da177e4SLinus Torvalds goto dput_and_out; 5151da177e4SLinus Torvalds 5161da177e4SLinus Torvalds retval = do_umount(nd.mnt, flags); 5171da177e4SLinus Torvalds dput_and_out: 5181da177e4SLinus Torvalds path_release_on_umount(&nd); 5191da177e4SLinus Torvalds out: 5201da177e4SLinus Torvalds return retval; 5211da177e4SLinus Torvalds } 5221da177e4SLinus Torvalds 5231da177e4SLinus Torvalds #ifdef __ARCH_WANT_SYS_OLDUMOUNT 5241da177e4SLinus Torvalds 5251da177e4SLinus Torvalds /* 5261da177e4SLinus Torvalds * The 2.0 compatible umount. No flags. 5271da177e4SLinus Torvalds */ 5281da177e4SLinus Torvalds 5291da177e4SLinus Torvalds asmlinkage long sys_oldumount(char __user * name) 5301da177e4SLinus Torvalds { 5311da177e4SLinus Torvalds return sys_umount(name,0); 5321da177e4SLinus Torvalds } 5331da177e4SLinus Torvalds 5341da177e4SLinus Torvalds #endif 5351da177e4SLinus Torvalds 5361da177e4SLinus Torvalds static int mount_is_safe(struct nameidata *nd) 5371da177e4SLinus Torvalds { 5381da177e4SLinus Torvalds if (capable(CAP_SYS_ADMIN)) 5391da177e4SLinus Torvalds return 0; 5401da177e4SLinus Torvalds return -EPERM; 5411da177e4SLinus Torvalds #ifdef notyet 5421da177e4SLinus Torvalds if (S_ISLNK(nd->dentry->d_inode->i_mode)) 5431da177e4SLinus Torvalds return -EPERM; 5441da177e4SLinus Torvalds if (nd->dentry->d_inode->i_mode & S_ISVTX) { 5451da177e4SLinus Torvalds if (current->uid != nd->dentry->d_inode->i_uid) 5461da177e4SLinus Torvalds return -EPERM; 5471da177e4SLinus Torvalds } 5481da177e4SLinus Torvalds if (permission(nd->dentry->d_inode, MAY_WRITE, nd)) 5491da177e4SLinus Torvalds return -EPERM; 5501da177e4SLinus Torvalds return 0; 5511da177e4SLinus Torvalds #endif 5521da177e4SLinus Torvalds } 5531da177e4SLinus Torvalds 5541da177e4SLinus Torvalds static int 5551da177e4SLinus Torvalds lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) 5561da177e4SLinus Torvalds { 5571da177e4SLinus Torvalds while (1) { 5581da177e4SLinus Torvalds if (d == dentry) 5591da177e4SLinus Torvalds return 1; 5601da177e4SLinus Torvalds if (d == NULL || d == d->d_parent) 5611da177e4SLinus Torvalds return 0; 5621da177e4SLinus Torvalds d = d->d_parent; 5631da177e4SLinus Torvalds } 5641da177e4SLinus Torvalds } 5651da177e4SLinus Torvalds 5661da177e4SLinus Torvalds static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry) 5671da177e4SLinus Torvalds { 5681da177e4SLinus Torvalds struct vfsmount *res, *p, *q, *r, *s; 5691da177e4SLinus Torvalds struct nameidata nd; 5701da177e4SLinus Torvalds 5711da177e4SLinus Torvalds res = q = clone_mnt(mnt, dentry); 5721da177e4SLinus Torvalds if (!q) 5731da177e4SLinus Torvalds goto Enomem; 5741da177e4SLinus Torvalds q->mnt_mountpoint = mnt->mnt_mountpoint; 5751da177e4SLinus Torvalds 5761da177e4SLinus Torvalds p = mnt; 577fdadd65fSDomen Puncer list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { 5781da177e4SLinus Torvalds if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) 5791da177e4SLinus Torvalds continue; 5801da177e4SLinus Torvalds 5811da177e4SLinus Torvalds for (s = r; s; s = next_mnt(s, r)) { 5821da177e4SLinus Torvalds while (p != s->mnt_parent) { 5831da177e4SLinus Torvalds p = p->mnt_parent; 5841da177e4SLinus Torvalds q = q->mnt_parent; 5851da177e4SLinus Torvalds } 5861da177e4SLinus Torvalds p = s; 5871da177e4SLinus Torvalds nd.mnt = q; 5881da177e4SLinus Torvalds nd.dentry = p->mnt_mountpoint; 5891da177e4SLinus Torvalds q = clone_mnt(p, p->mnt_root); 5901da177e4SLinus Torvalds if (!q) 5911da177e4SLinus Torvalds goto Enomem; 5921da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 5931da177e4SLinus Torvalds list_add_tail(&q->mnt_list, &res->mnt_list); 5941da177e4SLinus Torvalds attach_mnt(q, &nd); 5951da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 5961da177e4SLinus Torvalds } 5971da177e4SLinus Torvalds } 5981da177e4SLinus Torvalds return res; 5991da177e4SLinus Torvalds Enomem: 6001da177e4SLinus Torvalds if (res) { 6011da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6021da177e4SLinus Torvalds umount_tree(res); 6031da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6041da177e4SLinus Torvalds } 6051da177e4SLinus Torvalds return NULL; 6061da177e4SLinus Torvalds } 6071da177e4SLinus Torvalds 6081da177e4SLinus Torvalds static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) 6091da177e4SLinus Torvalds { 6101da177e4SLinus Torvalds int err; 6111da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & MS_NOUSER) 6121da177e4SLinus Torvalds return -EINVAL; 6131da177e4SLinus Torvalds 6141da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 6151da177e4SLinus Torvalds S_ISDIR(mnt->mnt_root->d_inode->i_mode)) 6161da177e4SLinus Torvalds return -ENOTDIR; 6171da177e4SLinus Torvalds 6181da177e4SLinus Torvalds err = -ENOENT; 6191da177e4SLinus Torvalds down(&nd->dentry->d_inode->i_sem); 6201da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 6211da177e4SLinus Torvalds goto out_unlock; 6221da177e4SLinus Torvalds 6231da177e4SLinus Torvalds err = security_sb_check_sb(mnt, nd); 6241da177e4SLinus Torvalds if (err) 6251da177e4SLinus Torvalds goto out_unlock; 6261da177e4SLinus Torvalds 6271da177e4SLinus Torvalds err = -ENOENT; 6281da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6291da177e4SLinus Torvalds if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) { 6301da177e4SLinus Torvalds struct list_head head; 6311da177e4SLinus Torvalds 6321da177e4SLinus Torvalds attach_mnt(mnt, nd); 6331da177e4SLinus Torvalds list_add_tail(&head, &mnt->mnt_list); 6341da177e4SLinus Torvalds list_splice(&head, current->namespace->list.prev); 6351da177e4SLinus Torvalds mntget(mnt); 6361da177e4SLinus Torvalds err = 0; 6371da177e4SLinus Torvalds } 6381da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6391da177e4SLinus Torvalds out_unlock: 6401da177e4SLinus Torvalds up(&nd->dentry->d_inode->i_sem); 6411da177e4SLinus Torvalds if (!err) 6421da177e4SLinus Torvalds security_sb_post_addmount(mnt, nd); 6431da177e4SLinus Torvalds return err; 6441da177e4SLinus Torvalds } 6451da177e4SLinus Torvalds 6461da177e4SLinus Torvalds /* 6471da177e4SLinus Torvalds * do loopback mount. 6481da177e4SLinus Torvalds */ 6491da177e4SLinus Torvalds static int do_loopback(struct nameidata *nd, char *old_name, int recurse) 6501da177e4SLinus Torvalds { 6511da177e4SLinus Torvalds struct nameidata old_nd; 6521da177e4SLinus Torvalds struct vfsmount *mnt = NULL; 6531da177e4SLinus Torvalds int err = mount_is_safe(nd); 6541da177e4SLinus Torvalds if (err) 6551da177e4SLinus Torvalds return err; 6561da177e4SLinus Torvalds if (!old_name || !*old_name) 6571da177e4SLinus Torvalds return -EINVAL; 6581da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 6591da177e4SLinus Torvalds if (err) 6601da177e4SLinus Torvalds return err; 6611da177e4SLinus Torvalds 6621da177e4SLinus Torvalds down_write(¤t->namespace->sem); 6631da177e4SLinus Torvalds err = -EINVAL; 6641da177e4SLinus Torvalds if (check_mnt(nd->mnt) && (!recurse || check_mnt(old_nd.mnt))) { 6651da177e4SLinus Torvalds err = -ENOMEM; 6661da177e4SLinus Torvalds if (recurse) 6671da177e4SLinus Torvalds mnt = copy_tree(old_nd.mnt, old_nd.dentry); 6681da177e4SLinus Torvalds else 6691da177e4SLinus Torvalds mnt = clone_mnt(old_nd.mnt, old_nd.dentry); 6701da177e4SLinus Torvalds } 6711da177e4SLinus Torvalds 6721da177e4SLinus Torvalds if (mnt) { 6731da177e4SLinus Torvalds /* stop bind mounts from expiring */ 6741da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 67555e700b9SMiklos Szeredi list_del_init(&mnt->mnt_expire); 6761da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6771da177e4SLinus Torvalds 6781da177e4SLinus Torvalds err = graft_tree(mnt, nd); 6791da177e4SLinus Torvalds if (err) { 6801da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6811da177e4SLinus Torvalds umount_tree(mnt); 6821da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6831da177e4SLinus Torvalds } else 6841da177e4SLinus Torvalds mntput(mnt); 6851da177e4SLinus Torvalds } 6861da177e4SLinus Torvalds 6871da177e4SLinus Torvalds up_write(¤t->namespace->sem); 6881da177e4SLinus Torvalds path_release(&old_nd); 6891da177e4SLinus Torvalds return err; 6901da177e4SLinus Torvalds } 6911da177e4SLinus Torvalds 6921da177e4SLinus Torvalds /* 6931da177e4SLinus Torvalds * change filesystem flags. dir should be a physical root of filesystem. 6941da177e4SLinus Torvalds * If you've mounted a non-root directory somewhere and want to do remount 6951da177e4SLinus Torvalds * on it - tough luck. 6961da177e4SLinus Torvalds */ 6971da177e4SLinus Torvalds 6981da177e4SLinus Torvalds static int do_remount(struct nameidata *nd, int flags, int mnt_flags, 6991da177e4SLinus Torvalds void *data) 7001da177e4SLinus Torvalds { 7011da177e4SLinus Torvalds int err; 7021da177e4SLinus Torvalds struct super_block * sb = nd->mnt->mnt_sb; 7031da177e4SLinus Torvalds 7041da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 7051da177e4SLinus Torvalds return -EPERM; 7061da177e4SLinus Torvalds 7071da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 7081da177e4SLinus Torvalds return -EINVAL; 7091da177e4SLinus Torvalds 7101da177e4SLinus Torvalds if (nd->dentry != nd->mnt->mnt_root) 7111da177e4SLinus Torvalds return -EINVAL; 7121da177e4SLinus Torvalds 7131da177e4SLinus Torvalds down_write(&sb->s_umount); 7141da177e4SLinus Torvalds err = do_remount_sb(sb, flags, data, 0); 7151da177e4SLinus Torvalds if (!err) 7161da177e4SLinus Torvalds nd->mnt->mnt_flags=mnt_flags; 7171da177e4SLinus Torvalds up_write(&sb->s_umount); 7181da177e4SLinus Torvalds if (!err) 7191da177e4SLinus Torvalds security_sb_post_remount(nd->mnt, flags, data); 7201da177e4SLinus Torvalds return err; 7211da177e4SLinus Torvalds } 7221da177e4SLinus Torvalds 7231da177e4SLinus Torvalds static int do_move_mount(struct nameidata *nd, char *old_name) 7241da177e4SLinus Torvalds { 7251da177e4SLinus Torvalds struct nameidata old_nd, parent_nd; 7261da177e4SLinus Torvalds struct vfsmount *p; 7271da177e4SLinus Torvalds int err = 0; 7281da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 7291da177e4SLinus Torvalds return -EPERM; 7301da177e4SLinus Torvalds if (!old_name || !*old_name) 7311da177e4SLinus Torvalds return -EINVAL; 7321da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 7331da177e4SLinus Torvalds if (err) 7341da177e4SLinus Torvalds return err; 7351da177e4SLinus Torvalds 7361da177e4SLinus Torvalds down_write(¤t->namespace->sem); 7371da177e4SLinus Torvalds while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 7381da177e4SLinus Torvalds ; 7391da177e4SLinus Torvalds err = -EINVAL; 7401da177e4SLinus Torvalds if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) 7411da177e4SLinus Torvalds goto out; 7421da177e4SLinus Torvalds 7431da177e4SLinus Torvalds err = -ENOENT; 7441da177e4SLinus Torvalds down(&nd->dentry->d_inode->i_sem); 7451da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 7461da177e4SLinus Torvalds goto out1; 7471da177e4SLinus Torvalds 7481da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7491da177e4SLinus Torvalds if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) 7501da177e4SLinus Torvalds goto out2; 7511da177e4SLinus Torvalds 7521da177e4SLinus Torvalds err = -EINVAL; 7531da177e4SLinus Torvalds if (old_nd.dentry != old_nd.mnt->mnt_root) 7541da177e4SLinus Torvalds goto out2; 7551da177e4SLinus Torvalds 7561da177e4SLinus Torvalds if (old_nd.mnt == old_nd.mnt->mnt_parent) 7571da177e4SLinus Torvalds goto out2; 7581da177e4SLinus Torvalds 7591da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 7601da177e4SLinus Torvalds S_ISDIR(old_nd.dentry->d_inode->i_mode)) 7611da177e4SLinus Torvalds goto out2; 7621da177e4SLinus Torvalds 7631da177e4SLinus Torvalds err = -ELOOP; 7641da177e4SLinus Torvalds for (p = nd->mnt; p->mnt_parent!=p; p = p->mnt_parent) 7651da177e4SLinus Torvalds if (p == old_nd.mnt) 7661da177e4SLinus Torvalds goto out2; 7671da177e4SLinus Torvalds err = 0; 7681da177e4SLinus Torvalds 7691da177e4SLinus Torvalds detach_mnt(old_nd.mnt, &parent_nd); 7701da177e4SLinus Torvalds attach_mnt(old_nd.mnt, nd); 7711da177e4SLinus Torvalds 7721da177e4SLinus Torvalds /* if the mount is moved, it should no longer be expire 7731da177e4SLinus Torvalds * automatically */ 77455e700b9SMiklos Szeredi list_del_init(&old_nd.mnt->mnt_expire); 7751da177e4SLinus Torvalds out2: 7761da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7771da177e4SLinus Torvalds out1: 7781da177e4SLinus Torvalds up(&nd->dentry->d_inode->i_sem); 7791da177e4SLinus Torvalds out: 7801da177e4SLinus Torvalds up_write(¤t->namespace->sem); 7811da177e4SLinus Torvalds if (!err) 7821da177e4SLinus Torvalds path_release(&parent_nd); 7831da177e4SLinus Torvalds path_release(&old_nd); 7841da177e4SLinus Torvalds return err; 7851da177e4SLinus Torvalds } 7861da177e4SLinus Torvalds 7871da177e4SLinus Torvalds /* 7881da177e4SLinus Torvalds * create a new mount for userspace and request it to be added into the 7891da177e4SLinus Torvalds * namespace's tree 7901da177e4SLinus Torvalds */ 7911da177e4SLinus Torvalds static int do_new_mount(struct nameidata *nd, char *type, int flags, 7921da177e4SLinus Torvalds int mnt_flags, char *name, void *data) 7931da177e4SLinus Torvalds { 7941da177e4SLinus Torvalds struct vfsmount *mnt; 7951da177e4SLinus Torvalds 7961da177e4SLinus Torvalds if (!type || !memchr(type, 0, PAGE_SIZE)) 7971da177e4SLinus Torvalds return -EINVAL; 7981da177e4SLinus Torvalds 7991da177e4SLinus Torvalds /* we need capabilities... */ 8001da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 8011da177e4SLinus Torvalds return -EPERM; 8021da177e4SLinus Torvalds 8031da177e4SLinus Torvalds mnt = do_kern_mount(type, flags, name, data); 8041da177e4SLinus Torvalds if (IS_ERR(mnt)) 8051da177e4SLinus Torvalds return PTR_ERR(mnt); 8061da177e4SLinus Torvalds 8071da177e4SLinus Torvalds return do_add_mount(mnt, nd, mnt_flags, NULL); 8081da177e4SLinus Torvalds } 8091da177e4SLinus Torvalds 8101da177e4SLinus Torvalds /* 8111da177e4SLinus Torvalds * add a mount into a namespace's mount tree 8121da177e4SLinus Torvalds * - provide the option of adding the new mount to an expiration list 8131da177e4SLinus Torvalds */ 8141da177e4SLinus Torvalds int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, 8151da177e4SLinus Torvalds int mnt_flags, struct list_head *fslist) 8161da177e4SLinus Torvalds { 8171da177e4SLinus Torvalds int err; 8181da177e4SLinus Torvalds 8191da177e4SLinus Torvalds down_write(¤t->namespace->sem); 8201da177e4SLinus Torvalds /* Something was mounted here while we slept */ 8211da177e4SLinus Torvalds while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 8221da177e4SLinus Torvalds ; 8231da177e4SLinus Torvalds err = -EINVAL; 8241da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 8251da177e4SLinus Torvalds goto unlock; 8261da177e4SLinus Torvalds 8271da177e4SLinus Torvalds /* Refuse the same filesystem on the same mount point */ 8281da177e4SLinus Torvalds err = -EBUSY; 8291da177e4SLinus Torvalds if (nd->mnt->mnt_sb == newmnt->mnt_sb && 8301da177e4SLinus Torvalds nd->mnt->mnt_root == nd->dentry) 8311da177e4SLinus Torvalds goto unlock; 8321da177e4SLinus Torvalds 8331da177e4SLinus Torvalds err = -EINVAL; 8341da177e4SLinus Torvalds if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) 8351da177e4SLinus Torvalds goto unlock; 8361da177e4SLinus Torvalds 8371da177e4SLinus Torvalds newmnt->mnt_flags = mnt_flags; 838484e389cSMiklos Szeredi newmnt->mnt_namespace = current->namespace; 8391da177e4SLinus Torvalds err = graft_tree(newmnt, nd); 8401da177e4SLinus Torvalds 8411da177e4SLinus Torvalds if (err == 0 && fslist) { 8421da177e4SLinus Torvalds /* add to the specified expiration list */ 8431da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 84455e700b9SMiklos Szeredi list_add_tail(&newmnt->mnt_expire, fslist); 8451da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 8461da177e4SLinus Torvalds } 8471da177e4SLinus Torvalds 8481da177e4SLinus Torvalds unlock: 8491da177e4SLinus Torvalds up_write(¤t->namespace->sem); 8501da177e4SLinus Torvalds mntput(newmnt); 8511da177e4SLinus Torvalds return err; 8521da177e4SLinus Torvalds } 8531da177e4SLinus Torvalds 8541da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(do_add_mount); 8551da177e4SLinus Torvalds 85624ca2af1SMiklos Szeredi static void expire_mount(struct vfsmount *mnt, struct list_head *mounts) 85724ca2af1SMiklos Szeredi { 85824ca2af1SMiklos Szeredi spin_lock(&vfsmount_lock); 85924ca2af1SMiklos Szeredi 86024ca2af1SMiklos Szeredi /* 861ed42c879SMiklos Szeredi * Check if mount is still attached, if not, let whoever holds it deal 862ed42c879SMiklos Szeredi * with the sucker 863ed42c879SMiklos Szeredi */ 864ed42c879SMiklos Szeredi if (mnt->mnt_parent == mnt) { 865ed42c879SMiklos Szeredi spin_unlock(&vfsmount_lock); 866ed42c879SMiklos Szeredi return; 867ed42c879SMiklos Szeredi } 868ed42c879SMiklos Szeredi 869ed42c879SMiklos Szeredi /* 87024ca2af1SMiklos Szeredi * Check that it is still dead: the count should now be 2 - as 87124ca2af1SMiklos Szeredi * contributed by the vfsmount parent and the mntget above 87224ca2af1SMiklos Szeredi */ 87324ca2af1SMiklos Szeredi if (atomic_read(&mnt->mnt_count) == 2) { 87424ca2af1SMiklos Szeredi struct nameidata old_nd; 87524ca2af1SMiklos Szeredi 87624ca2af1SMiklos Szeredi /* delete from the namespace */ 87724ca2af1SMiklos Szeredi list_del_init(&mnt->mnt_list); 878ac081153SMiklos Szeredi mnt->mnt_namespace = NULL; 87924ca2af1SMiklos Szeredi detach_mnt(mnt, &old_nd); 88024ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 88124ca2af1SMiklos Szeredi path_release(&old_nd); 88224ca2af1SMiklos Szeredi mntput(mnt); 88324ca2af1SMiklos Szeredi } else { 88424ca2af1SMiklos Szeredi /* 88524ca2af1SMiklos Szeredi * Someone brought it back to life whilst we didn't have any 88624ca2af1SMiklos Szeredi * locks held so return it to the expiration list 88724ca2af1SMiklos Szeredi */ 88855e700b9SMiklos Szeredi list_add_tail(&mnt->mnt_expire, mounts); 88924ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 89024ca2af1SMiklos Szeredi } 89124ca2af1SMiklos Szeredi } 89224ca2af1SMiklos Szeredi 8931da177e4SLinus Torvalds /* 8941da177e4SLinus Torvalds * process a list of expirable mountpoints with the intent of discarding any 8951da177e4SLinus Torvalds * mountpoints that aren't in use and haven't been touched since last we came 8961da177e4SLinus Torvalds * here 8971da177e4SLinus Torvalds */ 8981da177e4SLinus Torvalds void mark_mounts_for_expiry(struct list_head *mounts) 8991da177e4SLinus Torvalds { 9001da177e4SLinus Torvalds struct namespace *namespace; 9011da177e4SLinus Torvalds struct vfsmount *mnt, *next; 9021da177e4SLinus Torvalds LIST_HEAD(graveyard); 9031da177e4SLinus Torvalds 9041da177e4SLinus Torvalds if (list_empty(mounts)) 9051da177e4SLinus Torvalds return; 9061da177e4SLinus Torvalds 9071da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 9081da177e4SLinus Torvalds 9091da177e4SLinus Torvalds /* extract from the expiration list every vfsmount that matches the 9101da177e4SLinus Torvalds * following criteria: 9111da177e4SLinus Torvalds * - only referenced by its parent vfsmount 9121da177e4SLinus Torvalds * - still marked for expiry (marked on the last call here; marks are 9131da177e4SLinus Torvalds * cleared by mntput()) 9141da177e4SLinus Torvalds */ 91555e700b9SMiklos Szeredi list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { 9161da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1) || 9171da177e4SLinus Torvalds atomic_read(&mnt->mnt_count) != 1) 9181da177e4SLinus Torvalds continue; 9191da177e4SLinus Torvalds 9201da177e4SLinus Torvalds mntget(mnt); 92155e700b9SMiklos Szeredi list_move(&mnt->mnt_expire, &graveyard); 9221da177e4SLinus Torvalds } 9231da177e4SLinus Torvalds 9241da177e4SLinus Torvalds /* 9251da177e4SLinus Torvalds * go through the vfsmounts we've just consigned to the graveyard to 9261da177e4SLinus Torvalds * - check that they're still dead 9271da177e4SLinus Torvalds * - delete the vfsmount from the appropriate namespace under lock 9281da177e4SLinus Torvalds * - dispose of the corpse 9291da177e4SLinus Torvalds */ 9301da177e4SLinus Torvalds while (!list_empty(&graveyard)) { 93155e700b9SMiklos Szeredi mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire); 93255e700b9SMiklos Szeredi list_del_init(&mnt->mnt_expire); 9331da177e4SLinus Torvalds 9341da177e4SLinus Torvalds /* don't do anything if the namespace is dead - all the 9351da177e4SLinus Torvalds * vfsmounts from it are going away anyway */ 9361da177e4SLinus Torvalds namespace = mnt->mnt_namespace; 9371ce88cf4SMiklos Szeredi if (!namespace || !namespace->root) 9381da177e4SLinus Torvalds continue; 9391da177e4SLinus Torvalds get_namespace(namespace); 9401da177e4SLinus Torvalds 9411da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 9421da177e4SLinus Torvalds down_write(&namespace->sem); 94324ca2af1SMiklos Szeredi expire_mount(mnt, mounts); 9441da177e4SLinus Torvalds up_write(&namespace->sem); 9451da177e4SLinus Torvalds 9461da177e4SLinus Torvalds mntput(mnt); 9471da177e4SLinus Torvalds put_namespace(namespace); 9481da177e4SLinus Torvalds 9491da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 9501da177e4SLinus Torvalds } 9511da177e4SLinus Torvalds 9521da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 9531da177e4SLinus Torvalds } 9541da177e4SLinus Torvalds 9551da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); 9561da177e4SLinus Torvalds 9571da177e4SLinus Torvalds /* 9581da177e4SLinus Torvalds * Some copy_from_user() implementations do not return the exact number of 9591da177e4SLinus Torvalds * bytes remaining to copy on a fault. But copy_mount_options() requires that. 9601da177e4SLinus Torvalds * Note that this function differs from copy_from_user() in that it will oops 9611da177e4SLinus Torvalds * on bad values of `to', rather than returning a short copy. 9621da177e4SLinus Torvalds */ 9631da177e4SLinus Torvalds static long 9641da177e4SLinus Torvalds exact_copy_from_user(void *to, const void __user *from, unsigned long n) 9651da177e4SLinus Torvalds { 9661da177e4SLinus Torvalds char *t = to; 9671da177e4SLinus Torvalds const char __user *f = from; 9681da177e4SLinus Torvalds char c; 9691da177e4SLinus Torvalds 9701da177e4SLinus Torvalds if (!access_ok(VERIFY_READ, from, n)) 9711da177e4SLinus Torvalds return n; 9721da177e4SLinus Torvalds 9731da177e4SLinus Torvalds while (n) { 9741da177e4SLinus Torvalds if (__get_user(c, f)) { 9751da177e4SLinus Torvalds memset(t, 0, n); 9761da177e4SLinus Torvalds break; 9771da177e4SLinus Torvalds } 9781da177e4SLinus Torvalds *t++ = c; 9791da177e4SLinus Torvalds f++; 9801da177e4SLinus Torvalds n--; 9811da177e4SLinus Torvalds } 9821da177e4SLinus Torvalds return n; 9831da177e4SLinus Torvalds } 9841da177e4SLinus Torvalds 9851da177e4SLinus Torvalds int copy_mount_options(const void __user *data, unsigned long *where) 9861da177e4SLinus Torvalds { 9871da177e4SLinus Torvalds int i; 9881da177e4SLinus Torvalds unsigned long page; 9891da177e4SLinus Torvalds unsigned long size; 9901da177e4SLinus Torvalds 9911da177e4SLinus Torvalds *where = 0; 9921da177e4SLinus Torvalds if (!data) 9931da177e4SLinus Torvalds return 0; 9941da177e4SLinus Torvalds 9951da177e4SLinus Torvalds if (!(page = __get_free_page(GFP_KERNEL))) 9961da177e4SLinus Torvalds return -ENOMEM; 9971da177e4SLinus Torvalds 9981da177e4SLinus Torvalds /* We only care that *some* data at the address the user 9991da177e4SLinus Torvalds * gave us is valid. Just in case, we'll zero 10001da177e4SLinus Torvalds * the remainder of the page. 10011da177e4SLinus Torvalds */ 10021da177e4SLinus Torvalds /* copy_from_user cannot cross TASK_SIZE ! */ 10031da177e4SLinus Torvalds size = TASK_SIZE - (unsigned long)data; 10041da177e4SLinus Torvalds if (size > PAGE_SIZE) 10051da177e4SLinus Torvalds size = PAGE_SIZE; 10061da177e4SLinus Torvalds 10071da177e4SLinus Torvalds i = size - exact_copy_from_user((void *)page, data, size); 10081da177e4SLinus Torvalds if (!i) { 10091da177e4SLinus Torvalds free_page(page); 10101da177e4SLinus Torvalds return -EFAULT; 10111da177e4SLinus Torvalds } 10121da177e4SLinus Torvalds if (i != PAGE_SIZE) 10131da177e4SLinus Torvalds memset((char *)page + i, 0, PAGE_SIZE - i); 10141da177e4SLinus Torvalds *where = page; 10151da177e4SLinus Torvalds return 0; 10161da177e4SLinus Torvalds } 10171da177e4SLinus Torvalds 10181da177e4SLinus Torvalds /* 10191da177e4SLinus Torvalds * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to 10201da177e4SLinus Torvalds * be given to the mount() call (ie: read-only, no-dev, no-suid etc). 10211da177e4SLinus Torvalds * 10221da177e4SLinus Torvalds * data is a (void *) that can point to any structure up to 10231da177e4SLinus Torvalds * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent 10241da177e4SLinus Torvalds * information (or be NULL). 10251da177e4SLinus Torvalds * 10261da177e4SLinus Torvalds * Pre-0.97 versions of mount() didn't have a flags word. 10271da177e4SLinus Torvalds * When the flags word was introduced its top half was required 10281da177e4SLinus Torvalds * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. 10291da177e4SLinus Torvalds * Therefore, if this magic number is present, it carries no information 10301da177e4SLinus Torvalds * and must be discarded. 10311da177e4SLinus Torvalds */ 10321da177e4SLinus Torvalds long do_mount(char * dev_name, char * dir_name, char *type_page, 10331da177e4SLinus Torvalds unsigned long flags, void *data_page) 10341da177e4SLinus Torvalds { 10351da177e4SLinus Torvalds struct nameidata nd; 10361da177e4SLinus Torvalds int retval = 0; 10371da177e4SLinus Torvalds int mnt_flags = 0; 10381da177e4SLinus Torvalds 10391da177e4SLinus Torvalds /* Discard magic */ 10401da177e4SLinus Torvalds if ((flags & MS_MGC_MSK) == MS_MGC_VAL) 10411da177e4SLinus Torvalds flags &= ~MS_MGC_MSK; 10421da177e4SLinus Torvalds 10431da177e4SLinus Torvalds /* Basic sanity checks */ 10441da177e4SLinus Torvalds 10451da177e4SLinus Torvalds if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) 10461da177e4SLinus Torvalds return -EINVAL; 10471da177e4SLinus Torvalds if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) 10481da177e4SLinus Torvalds return -EINVAL; 10491da177e4SLinus Torvalds 10501da177e4SLinus Torvalds if (data_page) 10511da177e4SLinus Torvalds ((char *)data_page)[PAGE_SIZE - 1] = 0; 10521da177e4SLinus Torvalds 10531da177e4SLinus Torvalds /* Separate the per-mountpoint flags */ 10541da177e4SLinus Torvalds if (flags & MS_NOSUID) 10551da177e4SLinus Torvalds mnt_flags |= MNT_NOSUID; 10561da177e4SLinus Torvalds if (flags & MS_NODEV) 10571da177e4SLinus Torvalds mnt_flags |= MNT_NODEV; 10581da177e4SLinus Torvalds if (flags & MS_NOEXEC) 10591da177e4SLinus Torvalds mnt_flags |= MNT_NOEXEC; 10601da177e4SLinus Torvalds flags &= ~(MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_ACTIVE); 10611da177e4SLinus Torvalds 10621da177e4SLinus Torvalds /* ... and get the mountpoint */ 10631da177e4SLinus Torvalds retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); 10641da177e4SLinus Torvalds if (retval) 10651da177e4SLinus Torvalds return retval; 10661da177e4SLinus Torvalds 10671da177e4SLinus Torvalds retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); 10681da177e4SLinus Torvalds if (retval) 10691da177e4SLinus Torvalds goto dput_out; 10701da177e4SLinus Torvalds 10711da177e4SLinus Torvalds if (flags & MS_REMOUNT) 10721da177e4SLinus Torvalds retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, 10731da177e4SLinus Torvalds data_page); 10741da177e4SLinus Torvalds else if (flags & MS_BIND) 10751da177e4SLinus Torvalds retval = do_loopback(&nd, dev_name, flags & MS_REC); 10761da177e4SLinus Torvalds else if (flags & MS_MOVE) 10771da177e4SLinus Torvalds retval = do_move_mount(&nd, dev_name); 10781da177e4SLinus Torvalds else 10791da177e4SLinus Torvalds retval = do_new_mount(&nd, type_page, flags, mnt_flags, 10801da177e4SLinus Torvalds dev_name, data_page); 10811da177e4SLinus Torvalds dput_out: 10821da177e4SLinus Torvalds path_release(&nd); 10831da177e4SLinus Torvalds return retval; 10841da177e4SLinus Torvalds } 10851da177e4SLinus Torvalds 10861da177e4SLinus Torvalds int copy_namespace(int flags, struct task_struct *tsk) 10871da177e4SLinus Torvalds { 10881da177e4SLinus Torvalds struct namespace *namespace = tsk->namespace; 10891da177e4SLinus Torvalds struct namespace *new_ns; 10901da177e4SLinus Torvalds struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; 10911da177e4SLinus Torvalds struct fs_struct *fs = tsk->fs; 10921da177e4SLinus Torvalds struct vfsmount *p, *q; 10931da177e4SLinus Torvalds 10941da177e4SLinus Torvalds if (!namespace) 10951da177e4SLinus Torvalds return 0; 10961da177e4SLinus Torvalds 10971da177e4SLinus Torvalds get_namespace(namespace); 10981da177e4SLinus Torvalds 10991da177e4SLinus Torvalds if (!(flags & CLONE_NEWNS)) 11001da177e4SLinus Torvalds return 0; 11011da177e4SLinus Torvalds 11021da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) { 11031da177e4SLinus Torvalds put_namespace(namespace); 11041da177e4SLinus Torvalds return -EPERM; 11051da177e4SLinus Torvalds } 11061da177e4SLinus Torvalds 11071da177e4SLinus Torvalds new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL); 11081da177e4SLinus Torvalds if (!new_ns) 11091da177e4SLinus Torvalds goto out; 11101da177e4SLinus Torvalds 11111da177e4SLinus Torvalds atomic_set(&new_ns->count, 1); 11121da177e4SLinus Torvalds init_rwsem(&new_ns->sem); 11131da177e4SLinus Torvalds INIT_LIST_HEAD(&new_ns->list); 11141da177e4SLinus Torvalds 11151da177e4SLinus Torvalds down_write(&tsk->namespace->sem); 11161da177e4SLinus Torvalds /* First pass: copy the tree topology */ 11171da177e4SLinus Torvalds new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root); 11181da177e4SLinus Torvalds if (!new_ns->root) { 11191da177e4SLinus Torvalds up_write(&tsk->namespace->sem); 11201da177e4SLinus Torvalds kfree(new_ns); 11211da177e4SLinus Torvalds goto out; 11221da177e4SLinus Torvalds } 11231da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 11241da177e4SLinus Torvalds list_add_tail(&new_ns->list, &new_ns->root->mnt_list); 11251da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 11261da177e4SLinus Torvalds 11271da177e4SLinus Torvalds /* 11281da177e4SLinus Torvalds * Second pass: switch the tsk->fs->* elements and mark new vfsmounts 11291da177e4SLinus Torvalds * as belonging to new namespace. We have already acquired a private 11301da177e4SLinus Torvalds * fs_struct, so tsk->fs->lock is not needed. 11311da177e4SLinus Torvalds */ 11321da177e4SLinus Torvalds p = namespace->root; 11331da177e4SLinus Torvalds q = new_ns->root; 11341da177e4SLinus Torvalds while (p) { 11351da177e4SLinus Torvalds q->mnt_namespace = new_ns; 11361da177e4SLinus Torvalds if (fs) { 11371da177e4SLinus Torvalds if (p == fs->rootmnt) { 11381da177e4SLinus Torvalds rootmnt = p; 11391da177e4SLinus Torvalds fs->rootmnt = mntget(q); 11401da177e4SLinus Torvalds } 11411da177e4SLinus Torvalds if (p == fs->pwdmnt) { 11421da177e4SLinus Torvalds pwdmnt = p; 11431da177e4SLinus Torvalds fs->pwdmnt = mntget(q); 11441da177e4SLinus Torvalds } 11451da177e4SLinus Torvalds if (p == fs->altrootmnt) { 11461da177e4SLinus Torvalds altrootmnt = p; 11471da177e4SLinus Torvalds fs->altrootmnt = mntget(q); 11481da177e4SLinus Torvalds } 11491da177e4SLinus Torvalds } 11501da177e4SLinus Torvalds p = next_mnt(p, namespace->root); 11511da177e4SLinus Torvalds q = next_mnt(q, new_ns->root); 11521da177e4SLinus Torvalds } 11531da177e4SLinus Torvalds up_write(&tsk->namespace->sem); 11541da177e4SLinus Torvalds 11551da177e4SLinus Torvalds tsk->namespace = new_ns; 11561da177e4SLinus Torvalds 11571da177e4SLinus Torvalds if (rootmnt) 11581da177e4SLinus Torvalds mntput(rootmnt); 11591da177e4SLinus Torvalds if (pwdmnt) 11601da177e4SLinus Torvalds mntput(pwdmnt); 11611da177e4SLinus Torvalds if (altrootmnt) 11621da177e4SLinus Torvalds mntput(altrootmnt); 11631da177e4SLinus Torvalds 11641da177e4SLinus Torvalds put_namespace(namespace); 11651da177e4SLinus Torvalds return 0; 11661da177e4SLinus Torvalds 11671da177e4SLinus Torvalds out: 11681da177e4SLinus Torvalds put_namespace(namespace); 11691da177e4SLinus Torvalds return -ENOMEM; 11701da177e4SLinus Torvalds } 11711da177e4SLinus Torvalds 11721da177e4SLinus Torvalds asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, 11731da177e4SLinus Torvalds char __user * type, unsigned long flags, 11741da177e4SLinus Torvalds void __user * data) 11751da177e4SLinus Torvalds { 11761da177e4SLinus Torvalds int retval; 11771da177e4SLinus Torvalds unsigned long data_page; 11781da177e4SLinus Torvalds unsigned long type_page; 11791da177e4SLinus Torvalds unsigned long dev_page; 11801da177e4SLinus Torvalds char *dir_page; 11811da177e4SLinus Torvalds 11821da177e4SLinus Torvalds retval = copy_mount_options (type, &type_page); 11831da177e4SLinus Torvalds if (retval < 0) 11841da177e4SLinus Torvalds return retval; 11851da177e4SLinus Torvalds 11861da177e4SLinus Torvalds dir_page = getname(dir_name); 11871da177e4SLinus Torvalds retval = PTR_ERR(dir_page); 11881da177e4SLinus Torvalds if (IS_ERR(dir_page)) 11891da177e4SLinus Torvalds goto out1; 11901da177e4SLinus Torvalds 11911da177e4SLinus Torvalds retval = copy_mount_options (dev_name, &dev_page); 11921da177e4SLinus Torvalds if (retval < 0) 11931da177e4SLinus Torvalds goto out2; 11941da177e4SLinus Torvalds 11951da177e4SLinus Torvalds retval = copy_mount_options (data, &data_page); 11961da177e4SLinus Torvalds if (retval < 0) 11971da177e4SLinus Torvalds goto out3; 11981da177e4SLinus Torvalds 11991da177e4SLinus Torvalds lock_kernel(); 12001da177e4SLinus Torvalds retval = do_mount((char*)dev_page, dir_page, (char*)type_page, 12011da177e4SLinus Torvalds flags, (void*)data_page); 12021da177e4SLinus Torvalds unlock_kernel(); 12031da177e4SLinus Torvalds free_page(data_page); 12041da177e4SLinus Torvalds 12051da177e4SLinus Torvalds out3: 12061da177e4SLinus Torvalds free_page(dev_page); 12071da177e4SLinus Torvalds out2: 12081da177e4SLinus Torvalds putname(dir_page); 12091da177e4SLinus Torvalds out1: 12101da177e4SLinus Torvalds free_page(type_page); 12111da177e4SLinus Torvalds return retval; 12121da177e4SLinus Torvalds } 12131da177e4SLinus Torvalds 12141da177e4SLinus Torvalds /* 12151da177e4SLinus Torvalds * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. 12161da177e4SLinus Torvalds * It can block. Requires the big lock held. 12171da177e4SLinus Torvalds */ 12181da177e4SLinus Torvalds void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, 12191da177e4SLinus Torvalds struct dentry *dentry) 12201da177e4SLinus Torvalds { 12211da177e4SLinus Torvalds struct dentry *old_root; 12221da177e4SLinus Torvalds struct vfsmount *old_rootmnt; 12231da177e4SLinus Torvalds write_lock(&fs->lock); 12241da177e4SLinus Torvalds old_root = fs->root; 12251da177e4SLinus Torvalds old_rootmnt = fs->rootmnt; 12261da177e4SLinus Torvalds fs->rootmnt = mntget(mnt); 12271da177e4SLinus Torvalds fs->root = dget(dentry); 12281da177e4SLinus Torvalds write_unlock(&fs->lock); 12291da177e4SLinus Torvalds if (old_root) { 12301da177e4SLinus Torvalds dput(old_root); 12311da177e4SLinus Torvalds mntput(old_rootmnt); 12321da177e4SLinus Torvalds } 12331da177e4SLinus Torvalds } 12341da177e4SLinus Torvalds 12351da177e4SLinus Torvalds /* 12361da177e4SLinus Torvalds * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. 12371da177e4SLinus Torvalds * It can block. Requires the big lock held. 12381da177e4SLinus Torvalds */ 12391da177e4SLinus Torvalds void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, 12401da177e4SLinus Torvalds struct dentry *dentry) 12411da177e4SLinus Torvalds { 12421da177e4SLinus Torvalds struct dentry *old_pwd; 12431da177e4SLinus Torvalds struct vfsmount *old_pwdmnt; 12441da177e4SLinus Torvalds 12451da177e4SLinus Torvalds write_lock(&fs->lock); 12461da177e4SLinus Torvalds old_pwd = fs->pwd; 12471da177e4SLinus Torvalds old_pwdmnt = fs->pwdmnt; 12481da177e4SLinus Torvalds fs->pwdmnt = mntget(mnt); 12491da177e4SLinus Torvalds fs->pwd = dget(dentry); 12501da177e4SLinus Torvalds write_unlock(&fs->lock); 12511da177e4SLinus Torvalds 12521da177e4SLinus Torvalds if (old_pwd) { 12531da177e4SLinus Torvalds dput(old_pwd); 12541da177e4SLinus Torvalds mntput(old_pwdmnt); 12551da177e4SLinus Torvalds } 12561da177e4SLinus Torvalds } 12571da177e4SLinus Torvalds 12581da177e4SLinus Torvalds static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) 12591da177e4SLinus Torvalds { 12601da177e4SLinus Torvalds struct task_struct *g, *p; 12611da177e4SLinus Torvalds struct fs_struct *fs; 12621da177e4SLinus Torvalds 12631da177e4SLinus Torvalds read_lock(&tasklist_lock); 12641da177e4SLinus Torvalds do_each_thread(g, p) { 12651da177e4SLinus Torvalds task_lock(p); 12661da177e4SLinus Torvalds fs = p->fs; 12671da177e4SLinus Torvalds if (fs) { 12681da177e4SLinus Torvalds atomic_inc(&fs->count); 12691da177e4SLinus Torvalds task_unlock(p); 12701da177e4SLinus Torvalds if (fs->root==old_nd->dentry&&fs->rootmnt==old_nd->mnt) 12711da177e4SLinus Torvalds set_fs_root(fs, new_nd->mnt, new_nd->dentry); 12721da177e4SLinus Torvalds if (fs->pwd==old_nd->dentry&&fs->pwdmnt==old_nd->mnt) 12731da177e4SLinus Torvalds set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); 12741da177e4SLinus Torvalds put_fs_struct(fs); 12751da177e4SLinus Torvalds } else 12761da177e4SLinus Torvalds task_unlock(p); 12771da177e4SLinus Torvalds } while_each_thread(g, p); 12781da177e4SLinus Torvalds read_unlock(&tasklist_lock); 12791da177e4SLinus Torvalds } 12801da177e4SLinus Torvalds 12811da177e4SLinus Torvalds /* 12821da177e4SLinus Torvalds * pivot_root Semantics: 12831da177e4SLinus Torvalds * Moves the root file system of the current process to the directory put_old, 12841da177e4SLinus Torvalds * makes new_root as the new root file system of the current process, and sets 12851da177e4SLinus Torvalds * root/cwd of all processes which had them on the current root to new_root. 12861da177e4SLinus Torvalds * 12871da177e4SLinus Torvalds * Restrictions: 12881da177e4SLinus Torvalds * The new_root and put_old must be directories, and must not be on the 12891da177e4SLinus Torvalds * same file system as the current process root. The put_old must be 12901da177e4SLinus Torvalds * underneath new_root, i.e. adding a non-zero number of /.. to the string 12911da177e4SLinus Torvalds * pointed to by put_old must yield the same directory as new_root. No other 12921da177e4SLinus Torvalds * file system may be mounted on put_old. After all, new_root is a mountpoint. 12931da177e4SLinus Torvalds * 12941da177e4SLinus Torvalds * Notes: 12951da177e4SLinus Torvalds * - we don't move root/cwd if they are not at the root (reason: if something 12961da177e4SLinus Torvalds * cared enough to change them, it's probably wrong to force them elsewhere) 12971da177e4SLinus Torvalds * - it's okay to pick a root that isn't the root of a file system, e.g. 12981da177e4SLinus Torvalds * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, 12991da177e4SLinus Torvalds * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root 13001da177e4SLinus Torvalds * first. 13011da177e4SLinus Torvalds */ 13021da177e4SLinus Torvalds 13031da177e4SLinus Torvalds asmlinkage long sys_pivot_root(const char __user *new_root, const char __user *put_old) 13041da177e4SLinus Torvalds { 13051da177e4SLinus Torvalds struct vfsmount *tmp; 13061da177e4SLinus Torvalds struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; 13071da177e4SLinus Torvalds int error; 13081da177e4SLinus Torvalds 13091da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 13101da177e4SLinus Torvalds return -EPERM; 13111da177e4SLinus Torvalds 13121da177e4SLinus Torvalds lock_kernel(); 13131da177e4SLinus Torvalds 13141da177e4SLinus Torvalds error = __user_walk(new_root, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &new_nd); 13151da177e4SLinus Torvalds if (error) 13161da177e4SLinus Torvalds goto out0; 13171da177e4SLinus Torvalds error = -EINVAL; 13181da177e4SLinus Torvalds if (!check_mnt(new_nd.mnt)) 13191da177e4SLinus Torvalds goto out1; 13201da177e4SLinus Torvalds 13211da177e4SLinus Torvalds error = __user_walk(put_old, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &old_nd); 13221da177e4SLinus Torvalds if (error) 13231da177e4SLinus Torvalds goto out1; 13241da177e4SLinus Torvalds 13251da177e4SLinus Torvalds error = security_sb_pivotroot(&old_nd, &new_nd); 13261da177e4SLinus Torvalds if (error) { 13271da177e4SLinus Torvalds path_release(&old_nd); 13281da177e4SLinus Torvalds goto out1; 13291da177e4SLinus Torvalds } 13301da177e4SLinus Torvalds 13311da177e4SLinus Torvalds read_lock(¤t->fs->lock); 13321da177e4SLinus Torvalds user_nd.mnt = mntget(current->fs->rootmnt); 13331da177e4SLinus Torvalds user_nd.dentry = dget(current->fs->root); 13341da177e4SLinus Torvalds read_unlock(¤t->fs->lock); 13351da177e4SLinus Torvalds down_write(¤t->namespace->sem); 13361da177e4SLinus Torvalds down(&old_nd.dentry->d_inode->i_sem); 13371da177e4SLinus Torvalds error = -EINVAL; 13381da177e4SLinus Torvalds if (!check_mnt(user_nd.mnt)) 13391da177e4SLinus Torvalds goto out2; 13401da177e4SLinus Torvalds error = -ENOENT; 13411da177e4SLinus Torvalds if (IS_DEADDIR(new_nd.dentry->d_inode)) 13421da177e4SLinus Torvalds goto out2; 13431da177e4SLinus Torvalds if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) 13441da177e4SLinus Torvalds goto out2; 13451da177e4SLinus Torvalds if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) 13461da177e4SLinus Torvalds goto out2; 13471da177e4SLinus Torvalds error = -EBUSY; 13481da177e4SLinus Torvalds if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) 13491da177e4SLinus Torvalds goto out2; /* loop, on the same file system */ 13501da177e4SLinus Torvalds error = -EINVAL; 13511da177e4SLinus Torvalds if (user_nd.mnt->mnt_root != user_nd.dentry) 13521da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 13530bb6fcc1SMiklos Szeredi if (user_nd.mnt->mnt_parent == user_nd.mnt) 13540bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 13551da177e4SLinus Torvalds if (new_nd.mnt->mnt_root != new_nd.dentry) 13561da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 13570bb6fcc1SMiklos Szeredi if (new_nd.mnt->mnt_parent == new_nd.mnt) 13580bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 13591da177e4SLinus Torvalds tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ 13601da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 13611da177e4SLinus Torvalds if (tmp != new_nd.mnt) { 13621da177e4SLinus Torvalds for (;;) { 13631da177e4SLinus Torvalds if (tmp->mnt_parent == tmp) 13641da177e4SLinus Torvalds goto out3; /* already mounted on put_old */ 13651da177e4SLinus Torvalds if (tmp->mnt_parent == new_nd.mnt) 13661da177e4SLinus Torvalds break; 13671da177e4SLinus Torvalds tmp = tmp->mnt_parent; 13681da177e4SLinus Torvalds } 13691da177e4SLinus Torvalds if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) 13701da177e4SLinus Torvalds goto out3; 13711da177e4SLinus Torvalds } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) 13721da177e4SLinus Torvalds goto out3; 13731da177e4SLinus Torvalds detach_mnt(new_nd.mnt, &parent_nd); 13741da177e4SLinus Torvalds detach_mnt(user_nd.mnt, &root_parent); 13751da177e4SLinus Torvalds attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ 13761da177e4SLinus Torvalds attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ 13771da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 13781da177e4SLinus Torvalds chroot_fs_refs(&user_nd, &new_nd); 13791da177e4SLinus Torvalds security_sb_post_pivotroot(&user_nd, &new_nd); 13801da177e4SLinus Torvalds error = 0; 13811da177e4SLinus Torvalds path_release(&root_parent); 13821da177e4SLinus Torvalds path_release(&parent_nd); 13831da177e4SLinus Torvalds out2: 13841da177e4SLinus Torvalds up(&old_nd.dentry->d_inode->i_sem); 13851da177e4SLinus Torvalds up_write(¤t->namespace->sem); 13861da177e4SLinus Torvalds path_release(&user_nd); 13871da177e4SLinus Torvalds path_release(&old_nd); 13881da177e4SLinus Torvalds out1: 13891da177e4SLinus Torvalds path_release(&new_nd); 13901da177e4SLinus Torvalds out0: 13911da177e4SLinus Torvalds unlock_kernel(); 13921da177e4SLinus Torvalds return error; 13931da177e4SLinus Torvalds out3: 13941da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 13951da177e4SLinus Torvalds goto out2; 13961da177e4SLinus Torvalds } 13971da177e4SLinus Torvalds 13981da177e4SLinus Torvalds static void __init init_mount_tree(void) 13991da177e4SLinus Torvalds { 14001da177e4SLinus Torvalds struct vfsmount *mnt; 14011da177e4SLinus Torvalds struct namespace *namespace; 14021da177e4SLinus Torvalds struct task_struct *g, *p; 14031da177e4SLinus Torvalds 14041da177e4SLinus Torvalds mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); 14051da177e4SLinus Torvalds if (IS_ERR(mnt)) 14061da177e4SLinus Torvalds panic("Can't create rootfs"); 14071da177e4SLinus Torvalds namespace = kmalloc(sizeof(*namespace), GFP_KERNEL); 14081da177e4SLinus Torvalds if (!namespace) 14091da177e4SLinus Torvalds panic("Can't allocate initial namespace"); 14101da177e4SLinus Torvalds atomic_set(&namespace->count, 1); 14111da177e4SLinus Torvalds INIT_LIST_HEAD(&namespace->list); 14121da177e4SLinus Torvalds init_rwsem(&namespace->sem); 14131da177e4SLinus Torvalds list_add(&mnt->mnt_list, &namespace->list); 14141da177e4SLinus Torvalds namespace->root = mnt; 14151da177e4SLinus Torvalds mnt->mnt_namespace = namespace; 14161da177e4SLinus Torvalds 14171da177e4SLinus Torvalds init_task.namespace = namespace; 14181da177e4SLinus Torvalds read_lock(&tasklist_lock); 14191da177e4SLinus Torvalds do_each_thread(g, p) { 14201da177e4SLinus Torvalds get_namespace(namespace); 14211da177e4SLinus Torvalds p->namespace = namespace; 14221da177e4SLinus Torvalds } while_each_thread(g, p); 14231da177e4SLinus Torvalds read_unlock(&tasklist_lock); 14241da177e4SLinus Torvalds 14251da177e4SLinus Torvalds set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root); 14261da177e4SLinus Torvalds set_fs_root(current->fs, namespace->root, namespace->root->mnt_root); 14271da177e4SLinus Torvalds } 14281da177e4SLinus Torvalds 14291da177e4SLinus Torvalds void __init mnt_init(unsigned long mempages) 14301da177e4SLinus Torvalds { 14311da177e4SLinus Torvalds struct list_head *d; 14321da177e4SLinus Torvalds unsigned int nr_hash; 14331da177e4SLinus Torvalds int i; 14341da177e4SLinus Torvalds 14351da177e4SLinus Torvalds mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), 14361da177e4SLinus Torvalds 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 14371da177e4SLinus Torvalds 14381da177e4SLinus Torvalds mount_hashtable = (struct list_head *) 14391da177e4SLinus Torvalds __get_free_page(GFP_ATOMIC); 14401da177e4SLinus Torvalds 14411da177e4SLinus Torvalds if (!mount_hashtable) 14421da177e4SLinus Torvalds panic("Failed to allocate mount hash table\n"); 14431da177e4SLinus Torvalds 14441da177e4SLinus Torvalds /* 14451da177e4SLinus Torvalds * Find the power-of-two list-heads that can fit into the allocation.. 14461da177e4SLinus Torvalds * We don't guarantee that "sizeof(struct list_head)" is necessarily 14471da177e4SLinus Torvalds * a power-of-two. 14481da177e4SLinus Torvalds */ 14491da177e4SLinus Torvalds nr_hash = PAGE_SIZE / sizeof(struct list_head); 14501da177e4SLinus Torvalds hash_bits = 0; 14511da177e4SLinus Torvalds do { 14521da177e4SLinus Torvalds hash_bits++; 14531da177e4SLinus Torvalds } while ((nr_hash >> hash_bits) != 0); 14541da177e4SLinus Torvalds hash_bits--; 14551da177e4SLinus Torvalds 14561da177e4SLinus Torvalds /* 14571da177e4SLinus Torvalds * Re-calculate the actual number of entries and the mask 14581da177e4SLinus Torvalds * from the number of bits we can fit. 14591da177e4SLinus Torvalds */ 14601da177e4SLinus Torvalds nr_hash = 1UL << hash_bits; 14611da177e4SLinus Torvalds hash_mask = nr_hash-1; 14621da177e4SLinus Torvalds 14631da177e4SLinus Torvalds printk("Mount-cache hash table entries: %d\n", nr_hash); 14641da177e4SLinus Torvalds 14651da177e4SLinus Torvalds /* And initialize the newly allocated array */ 14661da177e4SLinus Torvalds d = mount_hashtable; 14671da177e4SLinus Torvalds i = nr_hash; 14681da177e4SLinus Torvalds do { 14691da177e4SLinus Torvalds INIT_LIST_HEAD(d); 14701da177e4SLinus Torvalds d++; 14711da177e4SLinus Torvalds i--; 14721da177e4SLinus Torvalds } while (i); 14731da177e4SLinus Torvalds sysfs_init(); 14741da177e4SLinus Torvalds init_rootfs(); 14751da177e4SLinus Torvalds init_mount_tree(); 14761da177e4SLinus Torvalds } 14771da177e4SLinus Torvalds 14781da177e4SLinus Torvalds void __put_namespace(struct namespace *namespace) 14791da177e4SLinus Torvalds { 14801ce88cf4SMiklos Szeredi struct vfsmount *root = namespace->root; 14811ce88cf4SMiklos Szeredi namespace->root = NULL; 14821ce88cf4SMiklos Szeredi spin_unlock(&vfsmount_lock); 14831da177e4SLinus Torvalds down_write(&namespace->sem); 14841da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 14851ce88cf4SMiklos Szeredi umount_tree(root); 14861da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 14871da177e4SLinus Torvalds up_write(&namespace->sem); 14881da177e4SLinus Torvalds kfree(namespace); 14891da177e4SLinus Torvalds } 1490