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/syscalls.h> 121da177e4SLinus Torvalds #include <linux/slab.h> 131da177e4SLinus Torvalds #include <linux/sched.h> 141da177e4SLinus Torvalds #include <linux/smp_lock.h> 151da177e4SLinus Torvalds #include <linux/init.h> 1615a67dd8SRandy Dunlap #include <linux/kernel.h> 171da177e4SLinus Torvalds #include <linux/quotaops.h> 181da177e4SLinus Torvalds #include <linux/acct.h> 1916f7e0feSRandy Dunlap #include <linux/capability.h> 201da177e4SLinus Torvalds #include <linux/module.h> 21f20a9eadSAndrew Morton #include <linux/sysfs.h> 221da177e4SLinus Torvalds #include <linux/seq_file.h> 236b3286edSKirill Korotaev #include <linux/mnt_namespace.h> 241da177e4SLinus Torvalds #include <linux/namei.h> 251da177e4SLinus Torvalds #include <linux/security.h> 261da177e4SLinus Torvalds #include <linux/mount.h> 2707f3f05cSDavid Howells #include <linux/ramfs.h> 2813f14b4dSEric Dumazet #include <linux/log2.h> 291da177e4SLinus Torvalds #include <asm/uaccess.h> 301da177e4SLinus Torvalds #include <asm/unistd.h> 3107b20889SRam Pai #include "pnode.h" 32948730b0SAdrian Bunk #include "internal.h" 331da177e4SLinus Torvalds 3413f14b4dSEric Dumazet #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) 3513f14b4dSEric Dumazet #define HASH_SIZE (1UL << HASH_SHIFT) 3613f14b4dSEric Dumazet 371da177e4SLinus Torvalds /* spinlock for vfsmount related operations, inplace of dcache_lock */ 381da177e4SLinus Torvalds __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); 391da177e4SLinus Torvalds 405addc5ddSAl Viro static int event; 415addc5ddSAl Viro 42fa3536ccSEric Dumazet static struct list_head *mount_hashtable __read_mostly; 43e18b890bSChristoph Lameter static struct kmem_cache *mnt_cache __read_mostly; 44390c6843SRam Pai static struct rw_semaphore namespace_sem; 451da177e4SLinus Torvalds 46f87fd4c2SMiklos Szeredi /* /sys/fs */ 4700d26666SGreg Kroah-Hartman struct kobject *fs_kobj; 4800d26666SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(fs_kobj); 49f87fd4c2SMiklos Szeredi 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); 5413f14b4dSEric Dumazet tmp = tmp + (tmp >> HASH_SHIFT); 5513f14b4dSEric Dumazet return tmp & (HASH_SIZE - 1); 561da177e4SLinus Torvalds } 571da177e4SLinus Torvalds 581da177e4SLinus Torvalds struct vfsmount *alloc_vfsmnt(const char *name) 591da177e4SLinus Torvalds { 60c3762229SRobert P. J. Day struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); 611da177e4SLinus Torvalds if (mnt) { 621da177e4SLinus Torvalds atomic_set(&mnt->mnt_count, 1); 631da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_hash); 641da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_child); 651da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_mounts); 661da177e4SLinus Torvalds INIT_LIST_HEAD(&mnt->mnt_list); 6755e700b9SMiklos Szeredi INIT_LIST_HEAD(&mnt->mnt_expire); 6803e06e68SRam Pai INIT_LIST_HEAD(&mnt->mnt_share); 69a58b0eb8SRam Pai INIT_LIST_HEAD(&mnt->mnt_slave_list); 70a58b0eb8SRam Pai INIT_LIST_HEAD(&mnt->mnt_slave); 711da177e4SLinus Torvalds if (name) { 721da177e4SLinus Torvalds int size = strlen(name) + 1; 731da177e4SLinus Torvalds char *newname = kmalloc(size, GFP_KERNEL); 741da177e4SLinus Torvalds if (newname) { 751da177e4SLinus Torvalds memcpy(newname, name, size); 761da177e4SLinus Torvalds mnt->mnt_devname = newname; 771da177e4SLinus Torvalds } 781da177e4SLinus Torvalds } 791da177e4SLinus Torvalds } 801da177e4SLinus Torvalds return mnt; 811da177e4SLinus Torvalds } 821da177e4SLinus Torvalds 83454e2398SDavid Howells int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) 84454e2398SDavid Howells { 85454e2398SDavid Howells mnt->mnt_sb = sb; 86454e2398SDavid Howells mnt->mnt_root = dget(sb->s_root); 87454e2398SDavid Howells return 0; 88454e2398SDavid Howells } 89454e2398SDavid Howells 90454e2398SDavid Howells EXPORT_SYMBOL(simple_set_mnt); 91454e2398SDavid Howells 921da177e4SLinus Torvalds void free_vfsmnt(struct vfsmount *mnt) 931da177e4SLinus Torvalds { 941da177e4SLinus Torvalds kfree(mnt->mnt_devname); 951da177e4SLinus Torvalds kmem_cache_free(mnt_cache, mnt); 961da177e4SLinus Torvalds } 971da177e4SLinus Torvalds 981da177e4SLinus Torvalds /* 99a05964f3SRam Pai * find the first or last mount at @dentry on vfsmount @mnt depending on 100a05964f3SRam Pai * @dir. If @dir is set return the first mount else return the last mount. 1011da177e4SLinus Torvalds */ 102a05964f3SRam Pai struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, 103a05964f3SRam Pai int dir) 1041da177e4SLinus Torvalds { 1051da177e4SLinus Torvalds struct list_head *head = mount_hashtable + hash(mnt, dentry); 1061da177e4SLinus Torvalds struct list_head *tmp = head; 1071da177e4SLinus Torvalds struct vfsmount *p, *found = NULL; 1081da177e4SLinus Torvalds 1091da177e4SLinus Torvalds for (;;) { 110a05964f3SRam Pai tmp = dir ? tmp->next : tmp->prev; 1111da177e4SLinus Torvalds p = NULL; 1121da177e4SLinus Torvalds if (tmp == head) 1131da177e4SLinus Torvalds break; 1141da177e4SLinus Torvalds p = list_entry(tmp, struct vfsmount, mnt_hash); 1151da177e4SLinus Torvalds if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { 116a05964f3SRam Pai found = p; 1171da177e4SLinus Torvalds break; 1181da177e4SLinus Torvalds } 1191da177e4SLinus Torvalds } 1201da177e4SLinus Torvalds return found; 1211da177e4SLinus Torvalds } 1221da177e4SLinus Torvalds 123a05964f3SRam Pai /* 124a05964f3SRam Pai * lookup_mnt increments the ref count before returning 125a05964f3SRam Pai * the vfsmount struct. 126a05964f3SRam Pai */ 127a05964f3SRam Pai struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) 128a05964f3SRam Pai { 129a05964f3SRam Pai struct vfsmount *child_mnt; 130a05964f3SRam Pai spin_lock(&vfsmount_lock); 131a05964f3SRam Pai if ((child_mnt = __lookup_mnt(mnt, dentry, 1))) 132a05964f3SRam Pai mntget(child_mnt); 133a05964f3SRam Pai spin_unlock(&vfsmount_lock); 134a05964f3SRam Pai return child_mnt; 135a05964f3SRam Pai } 136a05964f3SRam Pai 1371da177e4SLinus Torvalds static inline int check_mnt(struct vfsmount *mnt) 1381da177e4SLinus Torvalds { 1396b3286edSKirill Korotaev return mnt->mnt_ns == current->nsproxy->mnt_ns; 1401da177e4SLinus Torvalds } 1411da177e4SLinus Torvalds 1426b3286edSKirill Korotaev static void touch_mnt_namespace(struct mnt_namespace *ns) 1435addc5ddSAl Viro { 1445addc5ddSAl Viro if (ns) { 1455addc5ddSAl Viro ns->event = ++event; 1465addc5ddSAl Viro wake_up_interruptible(&ns->poll); 1475addc5ddSAl Viro } 1485addc5ddSAl Viro } 1495addc5ddSAl Viro 1506b3286edSKirill Korotaev static void __touch_mnt_namespace(struct mnt_namespace *ns) 1515addc5ddSAl Viro { 1525addc5ddSAl Viro if (ns && ns->event != event) { 1535addc5ddSAl Viro ns->event = event; 1545addc5ddSAl Viro wake_up_interruptible(&ns->poll); 1555addc5ddSAl Viro } 1565addc5ddSAl Viro } 1575addc5ddSAl Viro 1581da177e4SLinus Torvalds static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) 1591da177e4SLinus Torvalds { 1601da177e4SLinus Torvalds old_nd->dentry = mnt->mnt_mountpoint; 1611da177e4SLinus Torvalds old_nd->mnt = mnt->mnt_parent; 1621da177e4SLinus Torvalds mnt->mnt_parent = mnt; 1631da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 1641da177e4SLinus Torvalds list_del_init(&mnt->mnt_child); 1651da177e4SLinus Torvalds list_del_init(&mnt->mnt_hash); 1661da177e4SLinus Torvalds old_nd->dentry->d_mounted--; 1671da177e4SLinus Torvalds } 1681da177e4SLinus Torvalds 169b90fa9aeSRam Pai void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, 170b90fa9aeSRam Pai struct vfsmount *child_mnt) 171b90fa9aeSRam Pai { 172b90fa9aeSRam Pai child_mnt->mnt_parent = mntget(mnt); 173b90fa9aeSRam Pai child_mnt->mnt_mountpoint = dget(dentry); 174b90fa9aeSRam Pai dentry->d_mounted++; 175b90fa9aeSRam Pai } 176b90fa9aeSRam Pai 1771da177e4SLinus Torvalds static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) 1781da177e4SLinus Torvalds { 179b90fa9aeSRam Pai mnt_set_mountpoint(nd->mnt, nd->dentry, mnt); 180b90fa9aeSRam Pai list_add_tail(&mnt->mnt_hash, mount_hashtable + 181b90fa9aeSRam Pai hash(nd->mnt, nd->dentry)); 1821da177e4SLinus Torvalds list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); 183b90fa9aeSRam Pai } 184b90fa9aeSRam Pai 185b90fa9aeSRam Pai /* 186b90fa9aeSRam Pai * the caller must hold vfsmount_lock 187b90fa9aeSRam Pai */ 188b90fa9aeSRam Pai static void commit_tree(struct vfsmount *mnt) 189b90fa9aeSRam Pai { 190b90fa9aeSRam Pai struct vfsmount *parent = mnt->mnt_parent; 191b90fa9aeSRam Pai struct vfsmount *m; 192b90fa9aeSRam Pai LIST_HEAD(head); 1936b3286edSKirill Korotaev struct mnt_namespace *n = parent->mnt_ns; 194b90fa9aeSRam Pai 195b90fa9aeSRam Pai BUG_ON(parent == mnt); 196b90fa9aeSRam Pai 197b90fa9aeSRam Pai list_add_tail(&head, &mnt->mnt_list); 198b90fa9aeSRam Pai list_for_each_entry(m, &head, mnt_list) 1996b3286edSKirill Korotaev m->mnt_ns = n; 200b90fa9aeSRam Pai list_splice(&head, n->list.prev); 201b90fa9aeSRam Pai 202b90fa9aeSRam Pai list_add_tail(&mnt->mnt_hash, mount_hashtable + 203b90fa9aeSRam Pai hash(parent, mnt->mnt_mountpoint)); 204b90fa9aeSRam Pai list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); 2056b3286edSKirill Korotaev touch_mnt_namespace(n); 2061da177e4SLinus Torvalds } 2071da177e4SLinus Torvalds 2081da177e4SLinus Torvalds static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) 2091da177e4SLinus Torvalds { 2101da177e4SLinus Torvalds struct list_head *next = p->mnt_mounts.next; 2111da177e4SLinus Torvalds if (next == &p->mnt_mounts) { 2121da177e4SLinus Torvalds while (1) { 2131da177e4SLinus Torvalds if (p == root) 2141da177e4SLinus Torvalds return NULL; 2151da177e4SLinus Torvalds next = p->mnt_child.next; 2161da177e4SLinus Torvalds if (next != &p->mnt_parent->mnt_mounts) 2171da177e4SLinus Torvalds break; 2181da177e4SLinus Torvalds p = p->mnt_parent; 2191da177e4SLinus Torvalds } 2201da177e4SLinus Torvalds } 2211da177e4SLinus Torvalds return list_entry(next, struct vfsmount, mnt_child); 2221da177e4SLinus Torvalds } 2231da177e4SLinus Torvalds 2249676f0c6SRam Pai static struct vfsmount *skip_mnt_tree(struct vfsmount *p) 2259676f0c6SRam Pai { 2269676f0c6SRam Pai struct list_head *prev = p->mnt_mounts.prev; 2279676f0c6SRam Pai while (prev != &p->mnt_mounts) { 2289676f0c6SRam Pai p = list_entry(prev, struct vfsmount, mnt_child); 2299676f0c6SRam Pai prev = p->mnt_mounts.prev; 2309676f0c6SRam Pai } 2319676f0c6SRam Pai return p; 2329676f0c6SRam Pai } 2339676f0c6SRam Pai 23436341f64SRam Pai static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, 23536341f64SRam Pai int flag) 2361da177e4SLinus Torvalds { 2371da177e4SLinus Torvalds struct super_block *sb = old->mnt_sb; 2381da177e4SLinus Torvalds struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); 2391da177e4SLinus Torvalds 2401da177e4SLinus Torvalds if (mnt) { 2411da177e4SLinus Torvalds mnt->mnt_flags = old->mnt_flags; 2421da177e4SLinus Torvalds atomic_inc(&sb->s_active); 2431da177e4SLinus Torvalds mnt->mnt_sb = sb; 2441da177e4SLinus Torvalds mnt->mnt_root = dget(root); 2451da177e4SLinus Torvalds mnt->mnt_mountpoint = mnt->mnt_root; 2461da177e4SLinus Torvalds mnt->mnt_parent = mnt; 247b90fa9aeSRam Pai 2485afe0022SRam Pai if (flag & CL_SLAVE) { 2495afe0022SRam Pai list_add(&mnt->mnt_slave, &old->mnt_slave_list); 2505afe0022SRam Pai mnt->mnt_master = old; 2515afe0022SRam Pai CLEAR_MNT_SHARED(mnt); 2528aec0809SAl Viro } else if (!(flag & CL_PRIVATE)) { 253b90fa9aeSRam Pai if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) 254b90fa9aeSRam Pai list_add(&mnt->mnt_share, &old->mnt_share); 2555afe0022SRam Pai if (IS_MNT_SLAVE(old)) 2565afe0022SRam Pai list_add(&mnt->mnt_slave, &old->mnt_slave); 2575afe0022SRam Pai mnt->mnt_master = old->mnt_master; 2585afe0022SRam Pai } 259b90fa9aeSRam Pai if (flag & CL_MAKE_SHARED) 260b90fa9aeSRam Pai set_mnt_shared(mnt); 2611da177e4SLinus Torvalds 2621da177e4SLinus Torvalds /* stick the duplicate mount on the same expiry list 2631da177e4SLinus Torvalds * as the original if that was on one */ 26436341f64SRam Pai if (flag & CL_EXPIRE) { 2651da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 26655e700b9SMiklos Szeredi if (!list_empty(&old->mnt_expire)) 26755e700b9SMiklos Szeredi list_add(&mnt->mnt_expire, &old->mnt_expire); 2681da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 2691da177e4SLinus Torvalds } 27036341f64SRam Pai } 2711da177e4SLinus Torvalds return mnt; 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds 2747b7b1aceSAl Viro static inline void __mntput(struct vfsmount *mnt) 2751da177e4SLinus Torvalds { 2761da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 2771da177e4SLinus Torvalds dput(mnt->mnt_root); 2781da177e4SLinus Torvalds free_vfsmnt(mnt); 2791da177e4SLinus Torvalds deactivate_super(sb); 2801da177e4SLinus Torvalds } 2811da177e4SLinus Torvalds 2827b7b1aceSAl Viro void mntput_no_expire(struct vfsmount *mnt) 2837b7b1aceSAl Viro { 2847b7b1aceSAl Viro repeat: 2857b7b1aceSAl Viro if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { 2867b7b1aceSAl Viro if (likely(!mnt->mnt_pinned)) { 2877b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2887b7b1aceSAl Viro __mntput(mnt); 2897b7b1aceSAl Viro return; 2907b7b1aceSAl Viro } 2917b7b1aceSAl Viro atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); 2927b7b1aceSAl Viro mnt->mnt_pinned = 0; 2937b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 2947b7b1aceSAl Viro acct_auto_close_mnt(mnt); 2957b7b1aceSAl Viro security_sb_umount_close(mnt); 2967b7b1aceSAl Viro goto repeat; 2977b7b1aceSAl Viro } 2987b7b1aceSAl Viro } 2997b7b1aceSAl Viro 3007b7b1aceSAl Viro EXPORT_SYMBOL(mntput_no_expire); 3017b7b1aceSAl Viro 3027b7b1aceSAl Viro void mnt_pin(struct vfsmount *mnt) 3037b7b1aceSAl Viro { 3047b7b1aceSAl Viro spin_lock(&vfsmount_lock); 3057b7b1aceSAl Viro mnt->mnt_pinned++; 3067b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 3077b7b1aceSAl Viro } 3087b7b1aceSAl Viro 3097b7b1aceSAl Viro EXPORT_SYMBOL(mnt_pin); 3107b7b1aceSAl Viro 3117b7b1aceSAl Viro void mnt_unpin(struct vfsmount *mnt) 3127b7b1aceSAl Viro { 3137b7b1aceSAl Viro spin_lock(&vfsmount_lock); 3147b7b1aceSAl Viro if (mnt->mnt_pinned) { 3157b7b1aceSAl Viro atomic_inc(&mnt->mnt_count); 3167b7b1aceSAl Viro mnt->mnt_pinned--; 3177b7b1aceSAl Viro } 3187b7b1aceSAl Viro spin_unlock(&vfsmount_lock); 3197b7b1aceSAl Viro } 3207b7b1aceSAl Viro 3217b7b1aceSAl Viro EXPORT_SYMBOL(mnt_unpin); 3221da177e4SLinus Torvalds 3231da177e4SLinus Torvalds /* iterator */ 3241da177e4SLinus Torvalds static void *m_start(struct seq_file *m, loff_t *pos) 3251da177e4SLinus Torvalds { 3266b3286edSKirill Korotaev struct mnt_namespace *n = m->private; 3271da177e4SLinus Torvalds 328390c6843SRam Pai down_read(&namespace_sem); 329b0765fb8SPavel Emelianov return seq_list_start(&n->list, *pos); 3301da177e4SLinus Torvalds } 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds static void *m_next(struct seq_file *m, void *v, loff_t *pos) 3331da177e4SLinus Torvalds { 3346b3286edSKirill Korotaev struct mnt_namespace *n = m->private; 335b0765fb8SPavel Emelianov 336b0765fb8SPavel Emelianov return seq_list_next(v, &n->list, pos); 3371da177e4SLinus Torvalds } 3381da177e4SLinus Torvalds 3391da177e4SLinus Torvalds static void m_stop(struct seq_file *m, void *v) 3401da177e4SLinus Torvalds { 341390c6843SRam Pai up_read(&namespace_sem); 3421da177e4SLinus Torvalds } 3431da177e4SLinus Torvalds 3441da177e4SLinus Torvalds static inline void mangle(struct seq_file *m, const char *s) 3451da177e4SLinus Torvalds { 3461da177e4SLinus Torvalds seq_escape(m, s, " \t\n\\"); 3471da177e4SLinus Torvalds } 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds static int show_vfsmnt(struct seq_file *m, void *v) 3501da177e4SLinus Torvalds { 351b0765fb8SPavel Emelianov struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); 3521da177e4SLinus Torvalds int err = 0; 3531da177e4SLinus Torvalds static struct proc_fs_info { 3541da177e4SLinus Torvalds int flag; 3551da177e4SLinus Torvalds char *str; 3561da177e4SLinus Torvalds } fs_info[] = { 3571da177e4SLinus Torvalds { MS_SYNCHRONOUS, ",sync" }, 3581da177e4SLinus Torvalds { MS_DIRSYNC, ",dirsync" }, 3591da177e4SLinus Torvalds { MS_MANDLOCK, ",mand" }, 3601da177e4SLinus Torvalds { 0, NULL } 3611da177e4SLinus Torvalds }; 3621da177e4SLinus Torvalds static struct proc_fs_info mnt_info[] = { 3631da177e4SLinus Torvalds { MNT_NOSUID, ",nosuid" }, 3641da177e4SLinus Torvalds { MNT_NODEV, ",nodev" }, 3651da177e4SLinus Torvalds { MNT_NOEXEC, ",noexec" }, 366fc33a7bbSChristoph Hellwig { MNT_NOATIME, ",noatime" }, 367fc33a7bbSChristoph Hellwig { MNT_NODIRATIME, ",nodiratime" }, 36847ae32d6SValerie Henson { MNT_RELATIME, ",relatime" }, 3691da177e4SLinus Torvalds { 0, NULL } 3701da177e4SLinus Torvalds }; 3711da177e4SLinus Torvalds struct proc_fs_info *fs_infop; 3721da177e4SLinus Torvalds 3731da177e4SLinus Torvalds mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); 3741da177e4SLinus Torvalds seq_putc(m, ' '); 3751da177e4SLinus Torvalds seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); 3761da177e4SLinus Torvalds seq_putc(m, ' '); 3771da177e4SLinus Torvalds mangle(m, mnt->mnt_sb->s_type->name); 37879c0b2dfSMiklos Szeredi if (mnt->mnt_sb->s_subtype && mnt->mnt_sb->s_subtype[0]) { 37979c0b2dfSMiklos Szeredi seq_putc(m, '.'); 38079c0b2dfSMiklos Szeredi mangle(m, mnt->mnt_sb->s_subtype); 38179c0b2dfSMiklos Szeredi } 3821da177e4SLinus Torvalds seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); 3831da177e4SLinus Torvalds for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { 3841da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & fs_infop->flag) 3851da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 3861da177e4SLinus Torvalds } 3871da177e4SLinus Torvalds for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { 3881da177e4SLinus Torvalds if (mnt->mnt_flags & fs_infop->flag) 3891da177e4SLinus Torvalds seq_puts(m, fs_infop->str); 3901da177e4SLinus Torvalds } 3911da177e4SLinus Torvalds if (mnt->mnt_sb->s_op->show_options) 3921da177e4SLinus Torvalds err = mnt->mnt_sb->s_op->show_options(m, mnt); 3931da177e4SLinus Torvalds seq_puts(m, " 0 0\n"); 3941da177e4SLinus Torvalds return err; 3951da177e4SLinus Torvalds } 3961da177e4SLinus Torvalds 3971da177e4SLinus Torvalds struct seq_operations mounts_op = { 3981da177e4SLinus Torvalds .start = m_start, 3991da177e4SLinus Torvalds .next = m_next, 4001da177e4SLinus Torvalds .stop = m_stop, 4011da177e4SLinus Torvalds .show = show_vfsmnt 4021da177e4SLinus Torvalds }; 4031da177e4SLinus Torvalds 404b4629fe2SChuck Lever static int show_vfsstat(struct seq_file *m, void *v) 405b4629fe2SChuck Lever { 406b0765fb8SPavel Emelianov struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); 407b4629fe2SChuck Lever int err = 0; 408b4629fe2SChuck Lever 409b4629fe2SChuck Lever /* device */ 410b4629fe2SChuck Lever if (mnt->mnt_devname) { 411b4629fe2SChuck Lever seq_puts(m, "device "); 412b4629fe2SChuck Lever mangle(m, mnt->mnt_devname); 413b4629fe2SChuck Lever } else 414b4629fe2SChuck Lever seq_puts(m, "no device"); 415b4629fe2SChuck Lever 416b4629fe2SChuck Lever /* mount point */ 417b4629fe2SChuck Lever seq_puts(m, " mounted on "); 418b4629fe2SChuck Lever seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); 419b4629fe2SChuck Lever seq_putc(m, ' '); 420b4629fe2SChuck Lever 421b4629fe2SChuck Lever /* file system type */ 422b4629fe2SChuck Lever seq_puts(m, "with fstype "); 423b4629fe2SChuck Lever mangle(m, mnt->mnt_sb->s_type->name); 424b4629fe2SChuck Lever 425b4629fe2SChuck Lever /* optional statistics */ 426b4629fe2SChuck Lever if (mnt->mnt_sb->s_op->show_stats) { 427b4629fe2SChuck Lever seq_putc(m, ' '); 428b4629fe2SChuck Lever err = mnt->mnt_sb->s_op->show_stats(m, mnt); 429b4629fe2SChuck Lever } 430b4629fe2SChuck Lever 431b4629fe2SChuck Lever seq_putc(m, '\n'); 432b4629fe2SChuck Lever return err; 433b4629fe2SChuck Lever } 434b4629fe2SChuck Lever 435b4629fe2SChuck Lever struct seq_operations mountstats_op = { 436b4629fe2SChuck Lever .start = m_start, 437b4629fe2SChuck Lever .next = m_next, 438b4629fe2SChuck Lever .stop = m_stop, 439b4629fe2SChuck Lever .show = show_vfsstat, 440b4629fe2SChuck Lever }; 441b4629fe2SChuck Lever 4421da177e4SLinus Torvalds /** 4431da177e4SLinus Torvalds * may_umount_tree - check if a mount tree is busy 4441da177e4SLinus Torvalds * @mnt: root of mount tree 4451da177e4SLinus Torvalds * 4461da177e4SLinus Torvalds * This is called to check if a tree of mounts has any 4471da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts that are 4481da177e4SLinus Torvalds * busy. 4491da177e4SLinus Torvalds */ 4501da177e4SLinus Torvalds int may_umount_tree(struct vfsmount *mnt) 4511da177e4SLinus Torvalds { 45236341f64SRam Pai int actual_refs = 0; 45336341f64SRam Pai int minimum_refs = 0; 45436341f64SRam Pai struct vfsmount *p; 4551da177e4SLinus Torvalds 4561da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 45736341f64SRam Pai for (p = mnt; p; p = next_mnt(p, mnt)) { 4581da177e4SLinus Torvalds actual_refs += atomic_read(&p->mnt_count); 4591da177e4SLinus Torvalds minimum_refs += 2; 4601da177e4SLinus Torvalds } 4611da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 4621da177e4SLinus Torvalds 4631da177e4SLinus Torvalds if (actual_refs > minimum_refs) 4641da177e4SLinus Torvalds return 0; 465e3474a8eSIan Kent 466e3474a8eSIan Kent return 1; 4671da177e4SLinus Torvalds } 4681da177e4SLinus Torvalds 4691da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount_tree); 4701da177e4SLinus Torvalds 4711da177e4SLinus Torvalds /** 4721da177e4SLinus Torvalds * may_umount - check if a mount point is busy 4731da177e4SLinus Torvalds * @mnt: root of mount 4741da177e4SLinus Torvalds * 4751da177e4SLinus Torvalds * This is called to check if a mount point has any 4761da177e4SLinus Torvalds * open files, pwds, chroots or sub mounts. If the 4771da177e4SLinus Torvalds * mount has sub mounts this will return busy 4781da177e4SLinus Torvalds * regardless of whether the sub mounts are busy. 4791da177e4SLinus Torvalds * 4801da177e4SLinus Torvalds * Doesn't take quota and stuff into account. IOW, in some cases it will 4811da177e4SLinus Torvalds * give false negatives. The main reason why it's here is that we need 4821da177e4SLinus Torvalds * a non-destructive way to look for easily umountable filesystems. 4831da177e4SLinus Torvalds */ 4841da177e4SLinus Torvalds int may_umount(struct vfsmount *mnt) 4851da177e4SLinus Torvalds { 486e3474a8eSIan Kent int ret = 1; 487a05964f3SRam Pai spin_lock(&vfsmount_lock); 488a05964f3SRam Pai if (propagate_mount_busy(mnt, 2)) 489e3474a8eSIan Kent ret = 0; 490a05964f3SRam Pai spin_unlock(&vfsmount_lock); 491a05964f3SRam Pai return ret; 4921da177e4SLinus Torvalds } 4931da177e4SLinus Torvalds 4941da177e4SLinus Torvalds EXPORT_SYMBOL(may_umount); 4951da177e4SLinus Torvalds 496b90fa9aeSRam Pai void release_mounts(struct list_head *head) 4971da177e4SLinus Torvalds { 49870fbcdf4SRam Pai struct vfsmount *mnt; 49970fbcdf4SRam Pai while (!list_empty(head)) { 500b5e61818SPavel Emelianov mnt = list_first_entry(head, struct vfsmount, mnt_hash); 50170fbcdf4SRam Pai list_del_init(&mnt->mnt_hash); 50270fbcdf4SRam Pai if (mnt->mnt_parent != mnt) { 50370fbcdf4SRam Pai struct dentry *dentry; 50470fbcdf4SRam Pai struct vfsmount *m; 50570fbcdf4SRam Pai spin_lock(&vfsmount_lock); 50670fbcdf4SRam Pai dentry = mnt->mnt_mountpoint; 50770fbcdf4SRam Pai m = mnt->mnt_parent; 50870fbcdf4SRam Pai mnt->mnt_mountpoint = mnt->mnt_root; 50970fbcdf4SRam Pai mnt->mnt_parent = mnt; 5101da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 51170fbcdf4SRam Pai dput(dentry); 51270fbcdf4SRam Pai mntput(m); 5131da177e4SLinus Torvalds } 5141da177e4SLinus Torvalds mntput(mnt); 51570fbcdf4SRam Pai } 51670fbcdf4SRam Pai } 51770fbcdf4SRam Pai 518a05964f3SRam Pai void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) 51970fbcdf4SRam Pai { 52070fbcdf4SRam Pai struct vfsmount *p; 52170fbcdf4SRam Pai 5221bfba4e8SAkinobu Mita for (p = mnt; p; p = next_mnt(p, mnt)) 5231bfba4e8SAkinobu Mita list_move(&p->mnt_hash, kill); 52470fbcdf4SRam Pai 525a05964f3SRam Pai if (propagate) 526a05964f3SRam Pai propagate_umount(kill); 527a05964f3SRam Pai 52870fbcdf4SRam Pai list_for_each_entry(p, kill, mnt_hash) { 52970fbcdf4SRam Pai list_del_init(&p->mnt_expire); 53070fbcdf4SRam Pai list_del_init(&p->mnt_list); 5316b3286edSKirill Korotaev __touch_mnt_namespace(p->mnt_ns); 5326b3286edSKirill Korotaev p->mnt_ns = NULL; 53370fbcdf4SRam Pai list_del_init(&p->mnt_child); 53470fbcdf4SRam Pai if (p->mnt_parent != p) 535f30ac319SAl Viro p->mnt_mountpoint->d_mounted--; 536a05964f3SRam Pai change_mnt_propagation(p, MS_PRIVATE); 5371da177e4SLinus Torvalds } 5381da177e4SLinus Torvalds } 5391da177e4SLinus Torvalds 5401da177e4SLinus Torvalds static int do_umount(struct vfsmount *mnt, int flags) 5411da177e4SLinus Torvalds { 5421da177e4SLinus Torvalds struct super_block *sb = mnt->mnt_sb; 5431da177e4SLinus Torvalds int retval; 54470fbcdf4SRam Pai LIST_HEAD(umount_list); 5451da177e4SLinus Torvalds 5461da177e4SLinus Torvalds retval = security_sb_umount(mnt, flags); 5471da177e4SLinus Torvalds if (retval) 5481da177e4SLinus Torvalds return retval; 5491da177e4SLinus Torvalds 5501da177e4SLinus Torvalds /* 5511da177e4SLinus Torvalds * Allow userspace to request a mountpoint be expired rather than 5521da177e4SLinus Torvalds * unmounting unconditionally. Unmount only happens if: 5531da177e4SLinus Torvalds * (1) the mark is already set (the mark is cleared by mntput()) 5541da177e4SLinus Torvalds * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] 5551da177e4SLinus Torvalds */ 5561da177e4SLinus Torvalds if (flags & MNT_EXPIRE) { 5571da177e4SLinus Torvalds if (mnt == current->fs->rootmnt || 5581da177e4SLinus Torvalds flags & (MNT_FORCE | MNT_DETACH)) 5591da177e4SLinus Torvalds return -EINVAL; 5601da177e4SLinus Torvalds 5611da177e4SLinus Torvalds if (atomic_read(&mnt->mnt_count) != 2) 5621da177e4SLinus Torvalds return -EBUSY; 5631da177e4SLinus Torvalds 5641da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1)) 5651da177e4SLinus Torvalds return -EAGAIN; 5661da177e4SLinus Torvalds } 5671da177e4SLinus Torvalds 5681da177e4SLinus Torvalds /* 5691da177e4SLinus Torvalds * If we may have to abort operations to get out of this 5701da177e4SLinus Torvalds * mount, and they will themselves hold resources we must 5711da177e4SLinus Torvalds * allow the fs to do things. In the Unix tradition of 5721da177e4SLinus Torvalds * 'Gee thats tricky lets do it in userspace' the umount_begin 5731da177e4SLinus Torvalds * might fail to complete on the first run through as other tasks 5741da177e4SLinus Torvalds * must return, and the like. Thats for the mount program to worry 5751da177e4SLinus Torvalds * about for the moment. 5761da177e4SLinus Torvalds */ 5771da177e4SLinus Torvalds 5781da177e4SLinus Torvalds lock_kernel(); 5798b512d9aSTrond Myklebust if (sb->s_op->umount_begin) 5808b512d9aSTrond Myklebust sb->s_op->umount_begin(mnt, flags); 5811da177e4SLinus Torvalds unlock_kernel(); 5821da177e4SLinus Torvalds 5831da177e4SLinus Torvalds /* 5841da177e4SLinus Torvalds * No sense to grab the lock for this test, but test itself looks 5851da177e4SLinus Torvalds * somewhat bogus. Suggestions for better replacement? 5861da177e4SLinus Torvalds * Ho-hum... In principle, we might treat that as umount + switch 5871da177e4SLinus Torvalds * to rootfs. GC would eventually take care of the old vfsmount. 5881da177e4SLinus Torvalds * Actually it makes sense, especially if rootfs would contain a 5891da177e4SLinus Torvalds * /reboot - static binary that would close all descriptors and 5901da177e4SLinus Torvalds * call reboot(9). Then init(8) could umount root and exec /reboot. 5911da177e4SLinus Torvalds */ 5921da177e4SLinus Torvalds if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { 5931da177e4SLinus Torvalds /* 5941da177e4SLinus Torvalds * Special case for "unmounting" root ... 5951da177e4SLinus Torvalds * we just try to remount it readonly. 5961da177e4SLinus Torvalds */ 5971da177e4SLinus Torvalds down_write(&sb->s_umount); 5981da177e4SLinus Torvalds if (!(sb->s_flags & MS_RDONLY)) { 5991da177e4SLinus Torvalds lock_kernel(); 6001da177e4SLinus Torvalds DQUOT_OFF(sb); 6011da177e4SLinus Torvalds retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); 6021da177e4SLinus Torvalds unlock_kernel(); 6031da177e4SLinus Torvalds } 6041da177e4SLinus Torvalds up_write(&sb->s_umount); 6051da177e4SLinus Torvalds return retval; 6061da177e4SLinus Torvalds } 6071da177e4SLinus Torvalds 608390c6843SRam Pai down_write(&namespace_sem); 6091da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6105addc5ddSAl Viro event++; 6111da177e4SLinus Torvalds 6121da177e4SLinus Torvalds retval = -EBUSY; 613a05964f3SRam Pai if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { 6141da177e4SLinus Torvalds if (!list_empty(&mnt->mnt_list)) 615a05964f3SRam Pai umount_tree(mnt, 1, &umount_list); 6161da177e4SLinus Torvalds retval = 0; 6171da177e4SLinus Torvalds } 6181da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6191da177e4SLinus Torvalds if (retval) 6201da177e4SLinus Torvalds security_sb_umount_busy(mnt); 621390c6843SRam Pai up_write(&namespace_sem); 62270fbcdf4SRam Pai release_mounts(&umount_list); 6231da177e4SLinus Torvalds return retval; 6241da177e4SLinus Torvalds } 6251da177e4SLinus Torvalds 6261da177e4SLinus Torvalds /* 6271da177e4SLinus Torvalds * Now umount can handle mount points as well as block devices. 6281da177e4SLinus Torvalds * This is important for filesystems which use unnamed block devices. 6291da177e4SLinus Torvalds * 6301da177e4SLinus Torvalds * We now support a flag for forced unmount like the other 'big iron' 6311da177e4SLinus Torvalds * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD 6321da177e4SLinus Torvalds */ 6331da177e4SLinus Torvalds 6341da177e4SLinus Torvalds asmlinkage long sys_umount(char __user * name, int flags) 6351da177e4SLinus Torvalds { 6361da177e4SLinus Torvalds struct nameidata nd; 6371da177e4SLinus Torvalds int retval; 6381da177e4SLinus Torvalds 6391da177e4SLinus Torvalds retval = __user_walk(name, LOOKUP_FOLLOW, &nd); 6401da177e4SLinus Torvalds if (retval) 6411da177e4SLinus Torvalds goto out; 6421da177e4SLinus Torvalds retval = -EINVAL; 6431da177e4SLinus Torvalds if (nd.dentry != nd.mnt->mnt_root) 6441da177e4SLinus Torvalds goto dput_and_out; 6451da177e4SLinus Torvalds if (!check_mnt(nd.mnt)) 6461da177e4SLinus Torvalds goto dput_and_out; 6471da177e4SLinus Torvalds 6481da177e4SLinus Torvalds retval = -EPERM; 6491da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 6501da177e4SLinus Torvalds goto dput_and_out; 6511da177e4SLinus Torvalds 6521da177e4SLinus Torvalds retval = do_umount(nd.mnt, flags); 6531da177e4SLinus Torvalds dput_and_out: 6541da177e4SLinus Torvalds path_release_on_umount(&nd); 6551da177e4SLinus Torvalds out: 6561da177e4SLinus Torvalds return retval; 6571da177e4SLinus Torvalds } 6581da177e4SLinus Torvalds 6591da177e4SLinus Torvalds #ifdef __ARCH_WANT_SYS_OLDUMOUNT 6601da177e4SLinus Torvalds 6611da177e4SLinus Torvalds /* 6621da177e4SLinus Torvalds * The 2.0 compatible umount. No flags. 6631da177e4SLinus Torvalds */ 6641da177e4SLinus Torvalds asmlinkage long sys_oldumount(char __user * name) 6651da177e4SLinus Torvalds { 6661da177e4SLinus Torvalds return sys_umount(name, 0); 6671da177e4SLinus Torvalds } 6681da177e4SLinus Torvalds 6691da177e4SLinus Torvalds #endif 6701da177e4SLinus Torvalds 6711da177e4SLinus Torvalds static int mount_is_safe(struct nameidata *nd) 6721da177e4SLinus Torvalds { 6731da177e4SLinus Torvalds if (capable(CAP_SYS_ADMIN)) 6741da177e4SLinus Torvalds return 0; 6751da177e4SLinus Torvalds return -EPERM; 6761da177e4SLinus Torvalds #ifdef notyet 6771da177e4SLinus Torvalds if (S_ISLNK(nd->dentry->d_inode->i_mode)) 6781da177e4SLinus Torvalds return -EPERM; 6791da177e4SLinus Torvalds if (nd->dentry->d_inode->i_mode & S_ISVTX) { 6801da177e4SLinus Torvalds if (current->uid != nd->dentry->d_inode->i_uid) 6811da177e4SLinus Torvalds return -EPERM; 6821da177e4SLinus Torvalds } 683e4543eddSChristoph Hellwig if (vfs_permission(nd, MAY_WRITE)) 6841da177e4SLinus Torvalds return -EPERM; 6851da177e4SLinus Torvalds return 0; 6861da177e4SLinus Torvalds #endif 6871da177e4SLinus Torvalds } 6881da177e4SLinus Torvalds 689b58fed8bSRam Pai static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) 6901da177e4SLinus Torvalds { 6911da177e4SLinus Torvalds while (1) { 6921da177e4SLinus Torvalds if (d == dentry) 6931da177e4SLinus Torvalds return 1; 6941da177e4SLinus Torvalds if (d == NULL || d == d->d_parent) 6951da177e4SLinus Torvalds return 0; 6961da177e4SLinus Torvalds d = d->d_parent; 6971da177e4SLinus Torvalds } 6981da177e4SLinus Torvalds } 6991da177e4SLinus Torvalds 700b90fa9aeSRam Pai struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, 70136341f64SRam Pai int flag) 7021da177e4SLinus Torvalds { 7031da177e4SLinus Torvalds struct vfsmount *res, *p, *q, *r, *s; 7041da177e4SLinus Torvalds struct nameidata nd; 7051da177e4SLinus Torvalds 7069676f0c6SRam Pai if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) 7079676f0c6SRam Pai return NULL; 7089676f0c6SRam Pai 70936341f64SRam Pai res = q = clone_mnt(mnt, dentry, flag); 7101da177e4SLinus Torvalds if (!q) 7111da177e4SLinus Torvalds goto Enomem; 7121da177e4SLinus Torvalds q->mnt_mountpoint = mnt->mnt_mountpoint; 7131da177e4SLinus Torvalds 7141da177e4SLinus Torvalds p = mnt; 715fdadd65fSDomen Puncer list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { 7161da177e4SLinus Torvalds if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) 7171da177e4SLinus Torvalds continue; 7181da177e4SLinus Torvalds 7191da177e4SLinus Torvalds for (s = r; s; s = next_mnt(s, r)) { 7209676f0c6SRam Pai if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { 7219676f0c6SRam Pai s = skip_mnt_tree(s); 7229676f0c6SRam Pai continue; 7239676f0c6SRam Pai } 7241da177e4SLinus Torvalds while (p != s->mnt_parent) { 7251da177e4SLinus Torvalds p = p->mnt_parent; 7261da177e4SLinus Torvalds q = q->mnt_parent; 7271da177e4SLinus Torvalds } 7281da177e4SLinus Torvalds p = s; 7291da177e4SLinus Torvalds nd.mnt = q; 7301da177e4SLinus Torvalds nd.dentry = p->mnt_mountpoint; 73136341f64SRam Pai q = clone_mnt(p, p->mnt_root, flag); 7321da177e4SLinus Torvalds if (!q) 7331da177e4SLinus Torvalds goto Enomem; 7341da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7351da177e4SLinus Torvalds list_add_tail(&q->mnt_list, &res->mnt_list); 7361da177e4SLinus Torvalds attach_mnt(q, &nd); 7371da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7381da177e4SLinus Torvalds } 7391da177e4SLinus Torvalds } 7401da177e4SLinus Torvalds return res; 7411da177e4SLinus Torvalds Enomem: 7421da177e4SLinus Torvalds if (res) { 74370fbcdf4SRam Pai LIST_HEAD(umount_list); 7441da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 745a05964f3SRam Pai umount_tree(res, 0, &umount_list); 7461da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 74770fbcdf4SRam Pai release_mounts(&umount_list); 7481da177e4SLinus Torvalds } 7491da177e4SLinus Torvalds return NULL; 7501da177e4SLinus Torvalds } 7511da177e4SLinus Torvalds 7528aec0809SAl Viro struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry) 7538aec0809SAl Viro { 7548aec0809SAl Viro struct vfsmount *tree; 7558aec0809SAl Viro down_read(&namespace_sem); 7568aec0809SAl Viro tree = copy_tree(mnt, dentry, CL_COPY_ALL | CL_PRIVATE); 7578aec0809SAl Viro up_read(&namespace_sem); 7588aec0809SAl Viro return tree; 7598aec0809SAl Viro } 7608aec0809SAl Viro 7618aec0809SAl Viro void drop_collected_mounts(struct vfsmount *mnt) 7628aec0809SAl Viro { 7638aec0809SAl Viro LIST_HEAD(umount_list); 7648aec0809SAl Viro down_read(&namespace_sem); 7658aec0809SAl Viro spin_lock(&vfsmount_lock); 7668aec0809SAl Viro umount_tree(mnt, 0, &umount_list); 7678aec0809SAl Viro spin_unlock(&vfsmount_lock); 7688aec0809SAl Viro up_read(&namespace_sem); 7698aec0809SAl Viro release_mounts(&umount_list); 7708aec0809SAl Viro } 7718aec0809SAl Viro 772b90fa9aeSRam Pai /* 773b90fa9aeSRam Pai * @source_mnt : mount tree to be attached 774b90fa9aeSRam Pai * @nd : place the mount tree @source_mnt is attached 77521444403SRam Pai * @parent_nd : if non-null, detach the source_mnt from its parent and 77621444403SRam Pai * store the parent mount and mountpoint dentry. 77721444403SRam Pai * (done when source_mnt is moved) 778b90fa9aeSRam Pai * 779b90fa9aeSRam Pai * NOTE: in the table below explains the semantics when a source mount 780b90fa9aeSRam Pai * of a given type is attached to a destination mount of a given type. 7819676f0c6SRam Pai * --------------------------------------------------------------------------- 782b90fa9aeSRam Pai * | BIND MOUNT OPERATION | 7839676f0c6SRam Pai * |************************************************************************** 7849676f0c6SRam Pai * | source-->| shared | private | slave | unbindable | 7859676f0c6SRam Pai * | dest | | | | | 7869676f0c6SRam Pai * | | | | | | | 7879676f0c6SRam Pai * | v | | | | | 7889676f0c6SRam Pai * |************************************************************************** 7899676f0c6SRam Pai * | shared | shared (++) | shared (+) | shared(+++)| invalid | 7905afe0022SRam Pai * | | | | | | 7919676f0c6SRam Pai * |non-shared| shared (+) | private | slave (*) | invalid | 7929676f0c6SRam Pai * *************************************************************************** 793b90fa9aeSRam Pai * A bind operation clones the source mount and mounts the clone on the 794b90fa9aeSRam Pai * destination mount. 795b90fa9aeSRam Pai * 796b90fa9aeSRam Pai * (++) the cloned mount is propagated to all the mounts in the propagation 797b90fa9aeSRam Pai * tree of the destination mount and the cloned mount is added to 798b90fa9aeSRam Pai * the peer group of the source mount. 799b90fa9aeSRam Pai * (+) the cloned mount is created under the destination mount and is marked 800b90fa9aeSRam Pai * as shared. The cloned mount is added to the peer group of the source 801b90fa9aeSRam Pai * mount. 8025afe0022SRam Pai * (+++) the mount is propagated to all the mounts in the propagation tree 8035afe0022SRam Pai * of the destination mount and the cloned mount is made slave 8045afe0022SRam Pai * of the same master as that of the source mount. The cloned mount 8055afe0022SRam Pai * is marked as 'shared and slave'. 8065afe0022SRam Pai * (*) the cloned mount is made a slave of the same master as that of the 8075afe0022SRam Pai * source mount. 8085afe0022SRam Pai * 8099676f0c6SRam Pai * --------------------------------------------------------------------------- 81021444403SRam Pai * | MOVE MOUNT OPERATION | 8119676f0c6SRam Pai * |************************************************************************** 8129676f0c6SRam Pai * | source-->| shared | private | slave | unbindable | 8139676f0c6SRam Pai * | dest | | | | | 8149676f0c6SRam Pai * | | | | | | | 8159676f0c6SRam Pai * | v | | | | | 8169676f0c6SRam Pai * |************************************************************************** 8179676f0c6SRam Pai * | shared | shared (+) | shared (+) | shared(+++) | invalid | 8185afe0022SRam Pai * | | | | | | 8199676f0c6SRam Pai * |non-shared| shared (+*) | private | slave (*) | unbindable | 8209676f0c6SRam Pai * *************************************************************************** 8215afe0022SRam Pai * 8225afe0022SRam Pai * (+) the mount is moved to the destination. And is then propagated to 8235afe0022SRam Pai * all the mounts in the propagation tree of the destination mount. 82421444403SRam Pai * (+*) the mount is moved to the destination. 8255afe0022SRam Pai * (+++) the mount is moved to the destination and is then propagated to 8265afe0022SRam Pai * all the mounts belonging to the destination mount's propagation tree. 8275afe0022SRam Pai * the mount is marked as 'shared and slave'. 8285afe0022SRam Pai * (*) the mount continues to be a slave at the new location. 829b90fa9aeSRam Pai * 830b90fa9aeSRam Pai * if the source mount is a tree, the operations explained above is 831b90fa9aeSRam Pai * applied to each mount in the tree. 832b90fa9aeSRam Pai * Must be called without spinlocks held, since this function can sleep 833b90fa9aeSRam Pai * in allocations. 834b90fa9aeSRam Pai */ 835b90fa9aeSRam Pai static int attach_recursive_mnt(struct vfsmount *source_mnt, 83621444403SRam Pai struct nameidata *nd, struct nameidata *parent_nd) 837b90fa9aeSRam Pai { 838b90fa9aeSRam Pai LIST_HEAD(tree_list); 839b90fa9aeSRam Pai struct vfsmount *dest_mnt = nd->mnt; 840b90fa9aeSRam Pai struct dentry *dest_dentry = nd->dentry; 841b90fa9aeSRam Pai struct vfsmount *child, *p; 842b90fa9aeSRam Pai 843b90fa9aeSRam Pai if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) 844b90fa9aeSRam Pai return -EINVAL; 845b90fa9aeSRam Pai 846b90fa9aeSRam Pai if (IS_MNT_SHARED(dest_mnt)) { 847b90fa9aeSRam Pai for (p = source_mnt; p; p = next_mnt(p, source_mnt)) 848b90fa9aeSRam Pai set_mnt_shared(p); 849b90fa9aeSRam Pai } 850b90fa9aeSRam Pai 851b90fa9aeSRam Pai spin_lock(&vfsmount_lock); 85221444403SRam Pai if (parent_nd) { 85321444403SRam Pai detach_mnt(source_mnt, parent_nd); 85421444403SRam Pai attach_mnt(source_mnt, nd); 8556b3286edSKirill Korotaev touch_mnt_namespace(current->nsproxy->mnt_ns); 85621444403SRam Pai } else { 857b90fa9aeSRam Pai mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); 858b90fa9aeSRam Pai commit_tree(source_mnt); 85921444403SRam Pai } 860b90fa9aeSRam Pai 861b90fa9aeSRam Pai list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { 862b90fa9aeSRam Pai list_del_init(&child->mnt_hash); 863b90fa9aeSRam Pai commit_tree(child); 864b90fa9aeSRam Pai } 865b90fa9aeSRam Pai spin_unlock(&vfsmount_lock); 866b90fa9aeSRam Pai return 0; 867b90fa9aeSRam Pai } 868b90fa9aeSRam Pai 8691da177e4SLinus Torvalds static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) 8701da177e4SLinus Torvalds { 8711da177e4SLinus Torvalds int err; 8721da177e4SLinus Torvalds if (mnt->mnt_sb->s_flags & MS_NOUSER) 8731da177e4SLinus Torvalds return -EINVAL; 8741da177e4SLinus Torvalds 8751da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 8761da177e4SLinus Torvalds S_ISDIR(mnt->mnt_root->d_inode->i_mode)) 8771da177e4SLinus Torvalds return -ENOTDIR; 8781da177e4SLinus Torvalds 8791da177e4SLinus Torvalds err = -ENOENT; 8801b1dcc1bSJes Sorensen mutex_lock(&nd->dentry->d_inode->i_mutex); 8811da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 8821da177e4SLinus Torvalds goto out_unlock; 8831da177e4SLinus Torvalds 8841da177e4SLinus Torvalds err = security_sb_check_sb(mnt, nd); 8851da177e4SLinus Torvalds if (err) 8861da177e4SLinus Torvalds goto out_unlock; 8871da177e4SLinus Torvalds 8881da177e4SLinus Torvalds err = -ENOENT; 889b90fa9aeSRam Pai if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) 89021444403SRam Pai err = attach_recursive_mnt(mnt, nd, NULL); 8911da177e4SLinus Torvalds out_unlock: 8921b1dcc1bSJes Sorensen mutex_unlock(&nd->dentry->d_inode->i_mutex); 8931da177e4SLinus Torvalds if (!err) 8941da177e4SLinus Torvalds security_sb_post_addmount(mnt, nd); 8951da177e4SLinus Torvalds return err; 8961da177e4SLinus Torvalds } 8971da177e4SLinus Torvalds 8981da177e4SLinus Torvalds /* 89907b20889SRam Pai * recursively change the type of the mountpoint. 90007b20889SRam Pai */ 90107b20889SRam Pai static int do_change_type(struct nameidata *nd, int flag) 90207b20889SRam Pai { 90307b20889SRam Pai struct vfsmount *m, *mnt = nd->mnt; 90407b20889SRam Pai int recurse = flag & MS_REC; 90507b20889SRam Pai int type = flag & ~MS_REC; 90607b20889SRam Pai 907ee6f9582SMiklos Szeredi if (!capable(CAP_SYS_ADMIN)) 908ee6f9582SMiklos Szeredi return -EPERM; 909ee6f9582SMiklos Szeredi 91007b20889SRam Pai if (nd->dentry != nd->mnt->mnt_root) 91107b20889SRam Pai return -EINVAL; 91207b20889SRam Pai 91307b20889SRam Pai down_write(&namespace_sem); 91407b20889SRam Pai spin_lock(&vfsmount_lock); 91507b20889SRam Pai for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) 91607b20889SRam Pai change_mnt_propagation(m, type); 91707b20889SRam Pai spin_unlock(&vfsmount_lock); 91807b20889SRam Pai up_write(&namespace_sem); 91907b20889SRam Pai return 0; 92007b20889SRam Pai } 92107b20889SRam Pai 92207b20889SRam Pai /* 9231da177e4SLinus Torvalds * do loopback mount. 9241da177e4SLinus Torvalds */ 925eee391a6SAndrew Morton static int do_loopback(struct nameidata *nd, char *old_name, int recurse) 9261da177e4SLinus Torvalds { 9271da177e4SLinus Torvalds struct nameidata old_nd; 9281da177e4SLinus Torvalds struct vfsmount *mnt = NULL; 9291da177e4SLinus Torvalds int err = mount_is_safe(nd); 9301da177e4SLinus Torvalds if (err) 9311da177e4SLinus Torvalds return err; 9321da177e4SLinus Torvalds if (!old_name || !*old_name) 9331da177e4SLinus Torvalds return -EINVAL; 9341da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 9351da177e4SLinus Torvalds if (err) 9361da177e4SLinus Torvalds return err; 9371da177e4SLinus Torvalds 938390c6843SRam Pai down_write(&namespace_sem); 9391da177e4SLinus Torvalds err = -EINVAL; 9409676f0c6SRam Pai if (IS_MNT_UNBINDABLE(old_nd.mnt)) 9419676f0c6SRam Pai goto out; 9429676f0c6SRam Pai 943ccd48bc7SAl Viro if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) 944ccd48bc7SAl Viro goto out; 945ccd48bc7SAl Viro 9461da177e4SLinus Torvalds err = -ENOMEM; 9471da177e4SLinus Torvalds if (recurse) 94836341f64SRam Pai mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0); 9491da177e4SLinus Torvalds else 95036341f64SRam Pai mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0); 9511da177e4SLinus Torvalds 952ccd48bc7SAl Viro if (!mnt) 953ccd48bc7SAl Viro goto out; 954ccd48bc7SAl Viro 9551da177e4SLinus Torvalds err = graft_tree(mnt, nd); 9561da177e4SLinus Torvalds if (err) { 95770fbcdf4SRam Pai LIST_HEAD(umount_list); 9581da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 959a05964f3SRam Pai umount_tree(mnt, 0, &umount_list); 9601da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 96170fbcdf4SRam Pai release_mounts(&umount_list); 9625b83d2c5SRam Pai } 9631da177e4SLinus Torvalds 964ccd48bc7SAl Viro out: 965390c6843SRam Pai up_write(&namespace_sem); 9661da177e4SLinus Torvalds path_release(&old_nd); 9671da177e4SLinus Torvalds return err; 9681da177e4SLinus Torvalds } 9691da177e4SLinus Torvalds 9701da177e4SLinus Torvalds /* 9711da177e4SLinus Torvalds * change filesystem flags. dir should be a physical root of filesystem. 9721da177e4SLinus Torvalds * If you've mounted a non-root directory somewhere and want to do remount 9731da177e4SLinus Torvalds * on it - tough luck. 9741da177e4SLinus Torvalds */ 9751da177e4SLinus Torvalds static int do_remount(struct nameidata *nd, int flags, int mnt_flags, 9761da177e4SLinus Torvalds void *data) 9771da177e4SLinus Torvalds { 9781da177e4SLinus Torvalds int err; 9791da177e4SLinus Torvalds struct super_block *sb = nd->mnt->mnt_sb; 9801da177e4SLinus Torvalds 9811da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 9821da177e4SLinus Torvalds return -EPERM; 9831da177e4SLinus Torvalds 9841da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 9851da177e4SLinus Torvalds return -EINVAL; 9861da177e4SLinus Torvalds 9871da177e4SLinus Torvalds if (nd->dentry != nd->mnt->mnt_root) 9881da177e4SLinus Torvalds return -EINVAL; 9891da177e4SLinus Torvalds 9901da177e4SLinus Torvalds down_write(&sb->s_umount); 9911da177e4SLinus Torvalds err = do_remount_sb(sb, flags, data, 0); 9921da177e4SLinus Torvalds if (!err) 9931da177e4SLinus Torvalds nd->mnt->mnt_flags = mnt_flags; 9941da177e4SLinus Torvalds up_write(&sb->s_umount); 9951da177e4SLinus Torvalds if (!err) 9961da177e4SLinus Torvalds security_sb_post_remount(nd->mnt, flags, data); 9971da177e4SLinus Torvalds return err; 9981da177e4SLinus Torvalds } 9991da177e4SLinus Torvalds 10009676f0c6SRam Pai static inline int tree_contains_unbindable(struct vfsmount *mnt) 10019676f0c6SRam Pai { 10029676f0c6SRam Pai struct vfsmount *p; 10039676f0c6SRam Pai for (p = mnt; p; p = next_mnt(p, mnt)) { 10049676f0c6SRam Pai if (IS_MNT_UNBINDABLE(p)) 10059676f0c6SRam Pai return 1; 10069676f0c6SRam Pai } 10079676f0c6SRam Pai return 0; 10089676f0c6SRam Pai } 10099676f0c6SRam Pai 10101da177e4SLinus Torvalds static int do_move_mount(struct nameidata *nd, char *old_name) 10111da177e4SLinus Torvalds { 10121da177e4SLinus Torvalds struct nameidata old_nd, parent_nd; 10131da177e4SLinus Torvalds struct vfsmount *p; 10141da177e4SLinus Torvalds int err = 0; 10151da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 10161da177e4SLinus Torvalds return -EPERM; 10171da177e4SLinus Torvalds if (!old_name || !*old_name) 10181da177e4SLinus Torvalds return -EINVAL; 10191da177e4SLinus Torvalds err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); 10201da177e4SLinus Torvalds if (err) 10211da177e4SLinus Torvalds return err; 10221da177e4SLinus Torvalds 1023390c6843SRam Pai down_write(&namespace_sem); 10241da177e4SLinus Torvalds while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 10251da177e4SLinus Torvalds ; 10261da177e4SLinus Torvalds err = -EINVAL; 10271da177e4SLinus Torvalds if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) 10281da177e4SLinus Torvalds goto out; 10291da177e4SLinus Torvalds 10301da177e4SLinus Torvalds err = -ENOENT; 10311b1dcc1bSJes Sorensen mutex_lock(&nd->dentry->d_inode->i_mutex); 10321da177e4SLinus Torvalds if (IS_DEADDIR(nd->dentry->d_inode)) 10331da177e4SLinus Torvalds goto out1; 10341da177e4SLinus Torvalds 10351da177e4SLinus Torvalds if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) 103621444403SRam Pai goto out1; 10371da177e4SLinus Torvalds 10381da177e4SLinus Torvalds err = -EINVAL; 10391da177e4SLinus Torvalds if (old_nd.dentry != old_nd.mnt->mnt_root) 104021444403SRam Pai goto out1; 10411da177e4SLinus Torvalds 10421da177e4SLinus Torvalds if (old_nd.mnt == old_nd.mnt->mnt_parent) 104321444403SRam Pai goto out1; 10441da177e4SLinus Torvalds 10451da177e4SLinus Torvalds if (S_ISDIR(nd->dentry->d_inode->i_mode) != 10461da177e4SLinus Torvalds S_ISDIR(old_nd.dentry->d_inode->i_mode)) 104721444403SRam Pai goto out1; 104821444403SRam Pai /* 104921444403SRam Pai * Don't move a mount residing in a shared parent. 105021444403SRam Pai */ 105121444403SRam Pai if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent)) 105221444403SRam Pai goto out1; 10539676f0c6SRam Pai /* 10549676f0c6SRam Pai * Don't move a mount tree containing unbindable mounts to a destination 10559676f0c6SRam Pai * mount which is shared. 10569676f0c6SRam Pai */ 10579676f0c6SRam Pai if (IS_MNT_SHARED(nd->mnt) && tree_contains_unbindable(old_nd.mnt)) 10589676f0c6SRam Pai goto out1; 10591da177e4SLinus Torvalds err = -ELOOP; 10601da177e4SLinus Torvalds for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) 10611da177e4SLinus Torvalds if (p == old_nd.mnt) 106221444403SRam Pai goto out1; 10631da177e4SLinus Torvalds 106421444403SRam Pai if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd))) 106521444403SRam Pai goto out1; 10661da177e4SLinus Torvalds 106721444403SRam Pai spin_lock(&vfsmount_lock); 10681da177e4SLinus Torvalds /* if the mount is moved, it should no longer be expire 10691da177e4SLinus Torvalds * automatically */ 107055e700b9SMiklos Szeredi list_del_init(&old_nd.mnt->mnt_expire); 10711da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 10721da177e4SLinus Torvalds out1: 10731b1dcc1bSJes Sorensen mutex_unlock(&nd->dentry->d_inode->i_mutex); 10741da177e4SLinus Torvalds out: 1075390c6843SRam Pai up_write(&namespace_sem); 10761da177e4SLinus Torvalds if (!err) 10771da177e4SLinus Torvalds path_release(&parent_nd); 10781da177e4SLinus Torvalds path_release(&old_nd); 10791da177e4SLinus Torvalds return err; 10801da177e4SLinus Torvalds } 10811da177e4SLinus Torvalds 10821da177e4SLinus Torvalds /* 10831da177e4SLinus Torvalds * create a new mount for userspace and request it to be added into the 10841da177e4SLinus Torvalds * namespace's tree 10851da177e4SLinus Torvalds */ 10861da177e4SLinus Torvalds static int do_new_mount(struct nameidata *nd, char *type, int flags, 10871da177e4SLinus Torvalds int mnt_flags, char *name, void *data) 10881da177e4SLinus Torvalds { 10891da177e4SLinus Torvalds struct vfsmount *mnt; 10901da177e4SLinus Torvalds 10911da177e4SLinus Torvalds if (!type || !memchr(type, 0, PAGE_SIZE)) 10921da177e4SLinus Torvalds return -EINVAL; 10931da177e4SLinus Torvalds 10941da177e4SLinus Torvalds /* we need capabilities... */ 10951da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 10961da177e4SLinus Torvalds return -EPERM; 10971da177e4SLinus Torvalds 10981da177e4SLinus Torvalds mnt = do_kern_mount(type, flags, name, data); 10991da177e4SLinus Torvalds if (IS_ERR(mnt)) 11001da177e4SLinus Torvalds return PTR_ERR(mnt); 11011da177e4SLinus Torvalds 11021da177e4SLinus Torvalds return do_add_mount(mnt, nd, mnt_flags, NULL); 11031da177e4SLinus Torvalds } 11041da177e4SLinus Torvalds 11051da177e4SLinus Torvalds /* 11061da177e4SLinus Torvalds * add a mount into a namespace's mount tree 11071da177e4SLinus Torvalds * - provide the option of adding the new mount to an expiration list 11081da177e4SLinus Torvalds */ 11091da177e4SLinus Torvalds int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, 11101da177e4SLinus Torvalds int mnt_flags, struct list_head *fslist) 11111da177e4SLinus Torvalds { 11121da177e4SLinus Torvalds int err; 11131da177e4SLinus Torvalds 1114390c6843SRam Pai down_write(&namespace_sem); 11151da177e4SLinus Torvalds /* Something was mounted here while we slept */ 11161da177e4SLinus Torvalds while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) 11171da177e4SLinus Torvalds ; 11181da177e4SLinus Torvalds err = -EINVAL; 11191da177e4SLinus Torvalds if (!check_mnt(nd->mnt)) 11201da177e4SLinus Torvalds goto unlock; 11211da177e4SLinus Torvalds 11221da177e4SLinus Torvalds /* Refuse the same filesystem on the same mount point */ 11231da177e4SLinus Torvalds err = -EBUSY; 11241da177e4SLinus Torvalds if (nd->mnt->mnt_sb == newmnt->mnt_sb && 11251da177e4SLinus Torvalds nd->mnt->mnt_root == nd->dentry) 11261da177e4SLinus Torvalds goto unlock; 11271da177e4SLinus Torvalds 11281da177e4SLinus Torvalds err = -EINVAL; 11291da177e4SLinus Torvalds if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) 11301da177e4SLinus Torvalds goto unlock; 11311da177e4SLinus Torvalds 11321da177e4SLinus Torvalds newmnt->mnt_flags = mnt_flags; 11335b83d2c5SRam Pai if ((err = graft_tree(newmnt, nd))) 11345b83d2c5SRam Pai goto unlock; 11351da177e4SLinus Torvalds 11365b83d2c5SRam Pai if (fslist) { 11371da177e4SLinus Torvalds /* add to the specified expiration list */ 11381da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 113955e700b9SMiklos Szeredi list_add_tail(&newmnt->mnt_expire, fslist); 11401da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 11411da177e4SLinus Torvalds } 1142390c6843SRam Pai up_write(&namespace_sem); 11435b83d2c5SRam Pai return 0; 11441da177e4SLinus Torvalds 11451da177e4SLinus Torvalds unlock: 1146390c6843SRam Pai up_write(&namespace_sem); 11471da177e4SLinus Torvalds mntput(newmnt); 11481da177e4SLinus Torvalds return err; 11491da177e4SLinus Torvalds } 11501da177e4SLinus Torvalds 11511da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(do_add_mount); 11521da177e4SLinus Torvalds 115370fbcdf4SRam Pai static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, 115470fbcdf4SRam Pai struct list_head *umounts) 115524ca2af1SMiklos Szeredi { 115624ca2af1SMiklos Szeredi spin_lock(&vfsmount_lock); 115724ca2af1SMiklos Szeredi 115824ca2af1SMiklos Szeredi /* 1159ed42c879SMiklos Szeredi * Check if mount is still attached, if not, let whoever holds it deal 1160ed42c879SMiklos Szeredi * with the sucker 1161ed42c879SMiklos Szeredi */ 1162ed42c879SMiklos Szeredi if (mnt->mnt_parent == mnt) { 1163ed42c879SMiklos Szeredi spin_unlock(&vfsmount_lock); 1164ed42c879SMiklos Szeredi return; 1165ed42c879SMiklos Szeredi } 1166ed42c879SMiklos Szeredi 1167ed42c879SMiklos Szeredi /* 116824ca2af1SMiklos Szeredi * Check that it is still dead: the count should now be 2 - as 116924ca2af1SMiklos Szeredi * contributed by the vfsmount parent and the mntget above 117024ca2af1SMiklos Szeredi */ 1171a05964f3SRam Pai if (!propagate_mount_busy(mnt, 2)) { 117224ca2af1SMiklos Szeredi /* delete from the namespace */ 11736b3286edSKirill Korotaev touch_mnt_namespace(mnt->mnt_ns); 117424ca2af1SMiklos Szeredi list_del_init(&mnt->mnt_list); 11756b3286edSKirill Korotaev mnt->mnt_ns = NULL; 1176a05964f3SRam Pai umount_tree(mnt, 1, umounts); 117724ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 117824ca2af1SMiklos Szeredi } else { 117924ca2af1SMiklos Szeredi /* 118024ca2af1SMiklos Szeredi * Someone brought it back to life whilst we didn't have any 118124ca2af1SMiklos Szeredi * locks held so return it to the expiration list 118224ca2af1SMiklos Szeredi */ 118355e700b9SMiklos Szeredi list_add_tail(&mnt->mnt_expire, mounts); 118424ca2af1SMiklos Szeredi spin_unlock(&vfsmount_lock); 118524ca2af1SMiklos Szeredi } 118624ca2af1SMiklos Szeredi } 118724ca2af1SMiklos Szeredi 11881da177e4SLinus Torvalds /* 11895528f911STrond Myklebust * go through the vfsmounts we've just consigned to the graveyard to 11905528f911STrond Myklebust * - check that they're still dead 11915528f911STrond Myklebust * - delete the vfsmount from the appropriate namespace under lock 11925528f911STrond Myklebust * - dispose of the corpse 11935528f911STrond Myklebust */ 11945528f911STrond Myklebust static void expire_mount_list(struct list_head *graveyard, struct list_head *mounts) 11955528f911STrond Myklebust { 11966b3286edSKirill Korotaev struct mnt_namespace *ns; 11975528f911STrond Myklebust struct vfsmount *mnt; 11985528f911STrond Myklebust 11995528f911STrond Myklebust while (!list_empty(graveyard)) { 12005528f911STrond Myklebust LIST_HEAD(umounts); 1201b5e61818SPavel Emelianov mnt = list_first_entry(graveyard, struct vfsmount, mnt_expire); 12025528f911STrond Myklebust list_del_init(&mnt->mnt_expire); 12035528f911STrond Myklebust 12045528f911STrond Myklebust /* don't do anything if the namespace is dead - all the 12055528f911STrond Myklebust * vfsmounts from it are going away anyway */ 12066b3286edSKirill Korotaev ns = mnt->mnt_ns; 12076b3286edSKirill Korotaev if (!ns || !ns->root) 12085528f911STrond Myklebust continue; 12096b3286edSKirill Korotaev get_mnt_ns(ns); 12105528f911STrond Myklebust 12115528f911STrond Myklebust spin_unlock(&vfsmount_lock); 12125528f911STrond Myklebust down_write(&namespace_sem); 12135528f911STrond Myklebust expire_mount(mnt, mounts, &umounts); 12145528f911STrond Myklebust up_write(&namespace_sem); 12155528f911STrond Myklebust release_mounts(&umounts); 12165528f911STrond Myklebust mntput(mnt); 12176b3286edSKirill Korotaev put_mnt_ns(ns); 12185528f911STrond Myklebust spin_lock(&vfsmount_lock); 12195528f911STrond Myklebust } 12205528f911STrond Myklebust } 12215528f911STrond Myklebust 12225528f911STrond Myklebust /* 12231da177e4SLinus Torvalds * process a list of expirable mountpoints with the intent of discarding any 12241da177e4SLinus Torvalds * mountpoints that aren't in use and haven't been touched since last we came 12251da177e4SLinus Torvalds * here 12261da177e4SLinus Torvalds */ 12271da177e4SLinus Torvalds void mark_mounts_for_expiry(struct list_head *mounts) 12281da177e4SLinus Torvalds { 12291da177e4SLinus Torvalds struct vfsmount *mnt, *next; 12301da177e4SLinus Torvalds LIST_HEAD(graveyard); 12311da177e4SLinus Torvalds 12321da177e4SLinus Torvalds if (list_empty(mounts)) 12331da177e4SLinus Torvalds return; 12341da177e4SLinus Torvalds 12351da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 12361da177e4SLinus Torvalds 12371da177e4SLinus Torvalds /* extract from the expiration list every vfsmount that matches the 12381da177e4SLinus Torvalds * following criteria: 12391da177e4SLinus Torvalds * - only referenced by its parent vfsmount 12401da177e4SLinus Torvalds * - still marked for expiry (marked on the last call here; marks are 12411da177e4SLinus Torvalds * cleared by mntput()) 12421da177e4SLinus Torvalds */ 124355e700b9SMiklos Szeredi list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { 12441da177e4SLinus Torvalds if (!xchg(&mnt->mnt_expiry_mark, 1) || 12451da177e4SLinus Torvalds atomic_read(&mnt->mnt_count) != 1) 12461da177e4SLinus Torvalds continue; 12471da177e4SLinus Torvalds 12481da177e4SLinus Torvalds mntget(mnt); 124955e700b9SMiklos Szeredi list_move(&mnt->mnt_expire, &graveyard); 12501da177e4SLinus Torvalds } 12511da177e4SLinus Torvalds 12525528f911STrond Myklebust expire_mount_list(&graveyard, mounts); 12531da177e4SLinus Torvalds 12541da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 12551da177e4SLinus Torvalds } 12561da177e4SLinus Torvalds 12571da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); 12581da177e4SLinus Torvalds 12591da177e4SLinus Torvalds /* 12605528f911STrond Myklebust * Ripoff of 'select_parent()' 12615528f911STrond Myklebust * 12625528f911STrond Myklebust * search the list of submounts for a given mountpoint, and move any 12635528f911STrond Myklebust * shrinkable submounts to the 'graveyard' list. 12645528f911STrond Myklebust */ 12655528f911STrond Myklebust static int select_submounts(struct vfsmount *parent, struct list_head *graveyard) 12665528f911STrond Myklebust { 12675528f911STrond Myklebust struct vfsmount *this_parent = parent; 12685528f911STrond Myklebust struct list_head *next; 12695528f911STrond Myklebust int found = 0; 12705528f911STrond Myklebust 12715528f911STrond Myklebust repeat: 12725528f911STrond Myklebust next = this_parent->mnt_mounts.next; 12735528f911STrond Myklebust resume: 12745528f911STrond Myklebust while (next != &this_parent->mnt_mounts) { 12755528f911STrond Myklebust struct list_head *tmp = next; 12765528f911STrond Myklebust struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child); 12775528f911STrond Myklebust 12785528f911STrond Myklebust next = tmp->next; 12795528f911STrond Myklebust if (!(mnt->mnt_flags & MNT_SHRINKABLE)) 12805528f911STrond Myklebust continue; 12815528f911STrond Myklebust /* 12825528f911STrond Myklebust * Descend a level if the d_mounts list is non-empty. 12835528f911STrond Myklebust */ 12845528f911STrond Myklebust if (!list_empty(&mnt->mnt_mounts)) { 12855528f911STrond Myklebust this_parent = mnt; 12865528f911STrond Myklebust goto repeat; 12875528f911STrond Myklebust } 12885528f911STrond Myklebust 12895528f911STrond Myklebust if (!propagate_mount_busy(mnt, 1)) { 12905528f911STrond Myklebust mntget(mnt); 12915528f911STrond Myklebust list_move_tail(&mnt->mnt_expire, graveyard); 12925528f911STrond Myklebust found++; 12935528f911STrond Myklebust } 12945528f911STrond Myklebust } 12955528f911STrond Myklebust /* 12965528f911STrond Myklebust * All done at this level ... ascend and resume the search 12975528f911STrond Myklebust */ 12985528f911STrond Myklebust if (this_parent != parent) { 12995528f911STrond Myklebust next = this_parent->mnt_child.next; 13005528f911STrond Myklebust this_parent = this_parent->mnt_parent; 13015528f911STrond Myklebust goto resume; 13025528f911STrond Myklebust } 13035528f911STrond Myklebust return found; 13045528f911STrond Myklebust } 13055528f911STrond Myklebust 13065528f911STrond Myklebust /* 13075528f911STrond Myklebust * process a list of expirable mountpoints with the intent of discarding any 13085528f911STrond Myklebust * submounts of a specific parent mountpoint 13095528f911STrond Myklebust */ 13105528f911STrond Myklebust void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts) 13115528f911STrond Myklebust { 13125528f911STrond Myklebust LIST_HEAD(graveyard); 13135528f911STrond Myklebust int found; 13145528f911STrond Myklebust 13155528f911STrond Myklebust spin_lock(&vfsmount_lock); 13165528f911STrond Myklebust 13175528f911STrond Myklebust /* extract submounts of 'mountpoint' from the expiration list */ 13185528f911STrond Myklebust while ((found = select_submounts(mountpoint, &graveyard)) != 0) 13195528f911STrond Myklebust expire_mount_list(&graveyard, mounts); 13205528f911STrond Myklebust 13215528f911STrond Myklebust spin_unlock(&vfsmount_lock); 13225528f911STrond Myklebust } 13235528f911STrond Myklebust 13245528f911STrond Myklebust EXPORT_SYMBOL_GPL(shrink_submounts); 13255528f911STrond Myklebust 13265528f911STrond Myklebust /* 13271da177e4SLinus Torvalds * Some copy_from_user() implementations do not return the exact number of 13281da177e4SLinus Torvalds * bytes remaining to copy on a fault. But copy_mount_options() requires that. 13291da177e4SLinus Torvalds * Note that this function differs from copy_from_user() in that it will oops 13301da177e4SLinus Torvalds * on bad values of `to', rather than returning a short copy. 13311da177e4SLinus Torvalds */ 1332b58fed8bSRam Pai static long exact_copy_from_user(void *to, const void __user * from, 1333b58fed8bSRam Pai unsigned long n) 13341da177e4SLinus Torvalds { 13351da177e4SLinus Torvalds char *t = to; 13361da177e4SLinus Torvalds const char __user *f = from; 13371da177e4SLinus Torvalds char c; 13381da177e4SLinus Torvalds 13391da177e4SLinus Torvalds if (!access_ok(VERIFY_READ, from, n)) 13401da177e4SLinus Torvalds return n; 13411da177e4SLinus Torvalds 13421da177e4SLinus Torvalds while (n) { 13431da177e4SLinus Torvalds if (__get_user(c, f)) { 13441da177e4SLinus Torvalds memset(t, 0, n); 13451da177e4SLinus Torvalds break; 13461da177e4SLinus Torvalds } 13471da177e4SLinus Torvalds *t++ = c; 13481da177e4SLinus Torvalds f++; 13491da177e4SLinus Torvalds n--; 13501da177e4SLinus Torvalds } 13511da177e4SLinus Torvalds return n; 13521da177e4SLinus Torvalds } 13531da177e4SLinus Torvalds 13541da177e4SLinus Torvalds int copy_mount_options(const void __user * data, unsigned long *where) 13551da177e4SLinus Torvalds { 13561da177e4SLinus Torvalds int i; 13571da177e4SLinus Torvalds unsigned long page; 13581da177e4SLinus Torvalds unsigned long size; 13591da177e4SLinus Torvalds 13601da177e4SLinus Torvalds *where = 0; 13611da177e4SLinus Torvalds if (!data) 13621da177e4SLinus Torvalds return 0; 13631da177e4SLinus Torvalds 13641da177e4SLinus Torvalds if (!(page = __get_free_page(GFP_KERNEL))) 13651da177e4SLinus Torvalds return -ENOMEM; 13661da177e4SLinus Torvalds 13671da177e4SLinus Torvalds /* We only care that *some* data at the address the user 13681da177e4SLinus Torvalds * gave us is valid. Just in case, we'll zero 13691da177e4SLinus Torvalds * the remainder of the page. 13701da177e4SLinus Torvalds */ 13711da177e4SLinus Torvalds /* copy_from_user cannot cross TASK_SIZE ! */ 13721da177e4SLinus Torvalds size = TASK_SIZE - (unsigned long)data; 13731da177e4SLinus Torvalds if (size > PAGE_SIZE) 13741da177e4SLinus Torvalds size = PAGE_SIZE; 13751da177e4SLinus Torvalds 13761da177e4SLinus Torvalds i = size - exact_copy_from_user((void *)page, data, size); 13771da177e4SLinus Torvalds if (!i) { 13781da177e4SLinus Torvalds free_page(page); 13791da177e4SLinus Torvalds return -EFAULT; 13801da177e4SLinus Torvalds } 13811da177e4SLinus Torvalds if (i != PAGE_SIZE) 13821da177e4SLinus Torvalds memset((char *)page + i, 0, PAGE_SIZE - i); 13831da177e4SLinus Torvalds *where = page; 13841da177e4SLinus Torvalds return 0; 13851da177e4SLinus Torvalds } 13861da177e4SLinus Torvalds 13871da177e4SLinus Torvalds /* 13881da177e4SLinus Torvalds * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to 13891da177e4SLinus Torvalds * be given to the mount() call (ie: read-only, no-dev, no-suid etc). 13901da177e4SLinus Torvalds * 13911da177e4SLinus Torvalds * data is a (void *) that can point to any structure up to 13921da177e4SLinus Torvalds * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent 13931da177e4SLinus Torvalds * information (or be NULL). 13941da177e4SLinus Torvalds * 13951da177e4SLinus Torvalds * Pre-0.97 versions of mount() didn't have a flags word. 13961da177e4SLinus Torvalds * When the flags word was introduced its top half was required 13971da177e4SLinus Torvalds * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. 13981da177e4SLinus Torvalds * Therefore, if this magic number is present, it carries no information 13991da177e4SLinus Torvalds * and must be discarded. 14001da177e4SLinus Torvalds */ 14011da177e4SLinus Torvalds long do_mount(char *dev_name, char *dir_name, char *type_page, 14021da177e4SLinus Torvalds unsigned long flags, void *data_page) 14031da177e4SLinus Torvalds { 14041da177e4SLinus Torvalds struct nameidata nd; 14051da177e4SLinus Torvalds int retval = 0; 14061da177e4SLinus Torvalds int mnt_flags = 0; 14071da177e4SLinus Torvalds 14081da177e4SLinus Torvalds /* Discard magic */ 14091da177e4SLinus Torvalds if ((flags & MS_MGC_MSK) == MS_MGC_VAL) 14101da177e4SLinus Torvalds flags &= ~MS_MGC_MSK; 14111da177e4SLinus Torvalds 14121da177e4SLinus Torvalds /* Basic sanity checks */ 14131da177e4SLinus Torvalds 14141da177e4SLinus Torvalds if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) 14151da177e4SLinus Torvalds return -EINVAL; 14161da177e4SLinus Torvalds if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) 14171da177e4SLinus Torvalds return -EINVAL; 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds if (data_page) 14201da177e4SLinus Torvalds ((char *)data_page)[PAGE_SIZE - 1] = 0; 14211da177e4SLinus Torvalds 14221da177e4SLinus Torvalds /* Separate the per-mountpoint flags */ 14231da177e4SLinus Torvalds if (flags & MS_NOSUID) 14241da177e4SLinus Torvalds mnt_flags |= MNT_NOSUID; 14251da177e4SLinus Torvalds if (flags & MS_NODEV) 14261da177e4SLinus Torvalds mnt_flags |= MNT_NODEV; 14271da177e4SLinus Torvalds if (flags & MS_NOEXEC) 14281da177e4SLinus Torvalds mnt_flags |= MNT_NOEXEC; 1429fc33a7bbSChristoph Hellwig if (flags & MS_NOATIME) 1430fc33a7bbSChristoph Hellwig mnt_flags |= MNT_NOATIME; 1431fc33a7bbSChristoph Hellwig if (flags & MS_NODIRATIME) 1432fc33a7bbSChristoph Hellwig mnt_flags |= MNT_NODIRATIME; 143347ae32d6SValerie Henson if (flags & MS_RELATIME) 143447ae32d6SValerie Henson mnt_flags |= MNT_RELATIME; 1435fc33a7bbSChristoph Hellwig 1436fc33a7bbSChristoph Hellwig flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | 14378bf9725cSPavel Emelyanov MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT); 14381da177e4SLinus Torvalds 14391da177e4SLinus Torvalds /* ... and get the mountpoint */ 14401da177e4SLinus Torvalds retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); 14411da177e4SLinus Torvalds if (retval) 14421da177e4SLinus Torvalds return retval; 14431da177e4SLinus Torvalds 14441da177e4SLinus Torvalds retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); 14451da177e4SLinus Torvalds if (retval) 14461da177e4SLinus Torvalds goto dput_out; 14471da177e4SLinus Torvalds 14481da177e4SLinus Torvalds if (flags & MS_REMOUNT) 14491da177e4SLinus Torvalds retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, 14501da177e4SLinus Torvalds data_page); 14511da177e4SLinus Torvalds else if (flags & MS_BIND) 1452eee391a6SAndrew Morton retval = do_loopback(&nd, dev_name, flags & MS_REC); 14539676f0c6SRam Pai else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) 145407b20889SRam Pai retval = do_change_type(&nd, flags); 14551da177e4SLinus Torvalds else if (flags & MS_MOVE) 14561da177e4SLinus Torvalds retval = do_move_mount(&nd, dev_name); 14571da177e4SLinus Torvalds else 14581da177e4SLinus Torvalds retval = do_new_mount(&nd, type_page, flags, mnt_flags, 14591da177e4SLinus Torvalds dev_name, data_page); 14601da177e4SLinus Torvalds dput_out: 14611da177e4SLinus Torvalds path_release(&nd); 14621da177e4SLinus Torvalds return retval; 14631da177e4SLinus Torvalds } 14641da177e4SLinus Torvalds 1465741a2951SJANAK DESAI /* 1466741a2951SJANAK DESAI * Allocate a new namespace structure and populate it with contents 1467741a2951SJANAK DESAI * copied from the namespace of the passed in task structure. 1468741a2951SJANAK DESAI */ 1469e3222c4eSBadari Pulavarty static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, 14706b3286edSKirill Korotaev struct fs_struct *fs) 14711da177e4SLinus Torvalds { 14726b3286edSKirill Korotaev struct mnt_namespace *new_ns; 14731da177e4SLinus Torvalds struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; 14741da177e4SLinus Torvalds struct vfsmount *p, *q; 14751da177e4SLinus Torvalds 14766b3286edSKirill Korotaev new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); 14771da177e4SLinus Torvalds if (!new_ns) 1478467e9f4bSCedric Le Goater return ERR_PTR(-ENOMEM); 14791da177e4SLinus Torvalds 14801da177e4SLinus Torvalds atomic_set(&new_ns->count, 1); 14811da177e4SLinus Torvalds INIT_LIST_HEAD(&new_ns->list); 14825addc5ddSAl Viro init_waitqueue_head(&new_ns->poll); 14835addc5ddSAl Viro new_ns->event = 0; 14841da177e4SLinus Torvalds 1485390c6843SRam Pai down_write(&namespace_sem); 14861da177e4SLinus Torvalds /* First pass: copy the tree topology */ 14876b3286edSKirill Korotaev new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root, 14889676f0c6SRam Pai CL_COPY_ALL | CL_EXPIRE); 14891da177e4SLinus Torvalds if (!new_ns->root) { 1490390c6843SRam Pai up_write(&namespace_sem); 14911da177e4SLinus Torvalds kfree(new_ns); 1492467e9f4bSCedric Le Goater return ERR_PTR(-ENOMEM);; 14931da177e4SLinus Torvalds } 14941da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 14951da177e4SLinus Torvalds list_add_tail(&new_ns->list, &new_ns->root->mnt_list); 14961da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 14971da177e4SLinus Torvalds 14981da177e4SLinus Torvalds /* 14991da177e4SLinus Torvalds * Second pass: switch the tsk->fs->* elements and mark new vfsmounts 15001da177e4SLinus Torvalds * as belonging to new namespace. We have already acquired a private 15011da177e4SLinus Torvalds * fs_struct, so tsk->fs->lock is not needed. 15021da177e4SLinus Torvalds */ 15036b3286edSKirill Korotaev p = mnt_ns->root; 15041da177e4SLinus Torvalds q = new_ns->root; 15051da177e4SLinus Torvalds while (p) { 15066b3286edSKirill Korotaev q->mnt_ns = new_ns; 15071da177e4SLinus Torvalds if (fs) { 15081da177e4SLinus Torvalds if (p == fs->rootmnt) { 15091da177e4SLinus Torvalds rootmnt = p; 15101da177e4SLinus Torvalds fs->rootmnt = mntget(q); 15111da177e4SLinus Torvalds } 15121da177e4SLinus Torvalds if (p == fs->pwdmnt) { 15131da177e4SLinus Torvalds pwdmnt = p; 15141da177e4SLinus Torvalds fs->pwdmnt = mntget(q); 15151da177e4SLinus Torvalds } 15161da177e4SLinus Torvalds if (p == fs->altrootmnt) { 15171da177e4SLinus Torvalds altrootmnt = p; 15181da177e4SLinus Torvalds fs->altrootmnt = mntget(q); 15191da177e4SLinus Torvalds } 15201da177e4SLinus Torvalds } 15216b3286edSKirill Korotaev p = next_mnt(p, mnt_ns->root); 15221da177e4SLinus Torvalds q = next_mnt(q, new_ns->root); 15231da177e4SLinus Torvalds } 1524390c6843SRam Pai up_write(&namespace_sem); 15251da177e4SLinus Torvalds 15261da177e4SLinus Torvalds if (rootmnt) 15271da177e4SLinus Torvalds mntput(rootmnt); 15281da177e4SLinus Torvalds if (pwdmnt) 15291da177e4SLinus Torvalds mntput(pwdmnt); 15301da177e4SLinus Torvalds if (altrootmnt) 15311da177e4SLinus Torvalds mntput(altrootmnt); 15321da177e4SLinus Torvalds 1533741a2951SJANAK DESAI return new_ns; 1534741a2951SJANAK DESAI } 1535741a2951SJANAK DESAI 1536213dd266SEric W. Biederman struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, 1537e3222c4eSBadari Pulavarty struct fs_struct *new_fs) 1538741a2951SJANAK DESAI { 15396b3286edSKirill Korotaev struct mnt_namespace *new_ns; 1540741a2951SJANAK DESAI 1541e3222c4eSBadari Pulavarty BUG_ON(!ns); 15426b3286edSKirill Korotaev get_mnt_ns(ns); 1543741a2951SJANAK DESAI 1544741a2951SJANAK DESAI if (!(flags & CLONE_NEWNS)) 1545e3222c4eSBadari Pulavarty return ns; 1546741a2951SJANAK DESAI 1547e3222c4eSBadari Pulavarty new_ns = dup_mnt_ns(ns, new_fs); 1548741a2951SJANAK DESAI 15496b3286edSKirill Korotaev put_mnt_ns(ns); 1550e3222c4eSBadari Pulavarty return new_ns; 15511da177e4SLinus Torvalds } 15521da177e4SLinus Torvalds 15531da177e4SLinus Torvalds asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, 15541da177e4SLinus Torvalds char __user * type, unsigned long flags, 15551da177e4SLinus Torvalds void __user * data) 15561da177e4SLinus Torvalds { 15571da177e4SLinus Torvalds int retval; 15581da177e4SLinus Torvalds unsigned long data_page; 15591da177e4SLinus Torvalds unsigned long type_page; 15601da177e4SLinus Torvalds unsigned long dev_page; 15611da177e4SLinus Torvalds char *dir_page; 15621da177e4SLinus Torvalds 15631da177e4SLinus Torvalds retval = copy_mount_options(type, &type_page); 15641da177e4SLinus Torvalds if (retval < 0) 15651da177e4SLinus Torvalds return retval; 15661da177e4SLinus Torvalds 15671da177e4SLinus Torvalds dir_page = getname(dir_name); 15681da177e4SLinus Torvalds retval = PTR_ERR(dir_page); 15691da177e4SLinus Torvalds if (IS_ERR(dir_page)) 15701da177e4SLinus Torvalds goto out1; 15711da177e4SLinus Torvalds 15721da177e4SLinus Torvalds retval = copy_mount_options(dev_name, &dev_page); 15731da177e4SLinus Torvalds if (retval < 0) 15741da177e4SLinus Torvalds goto out2; 15751da177e4SLinus Torvalds 15761da177e4SLinus Torvalds retval = copy_mount_options(data, &data_page); 15771da177e4SLinus Torvalds if (retval < 0) 15781da177e4SLinus Torvalds goto out3; 15791da177e4SLinus Torvalds 15801da177e4SLinus Torvalds lock_kernel(); 15811da177e4SLinus Torvalds retval = do_mount((char *)dev_page, dir_page, (char *)type_page, 15821da177e4SLinus Torvalds flags, (void *)data_page); 15831da177e4SLinus Torvalds unlock_kernel(); 15841da177e4SLinus Torvalds free_page(data_page); 15851da177e4SLinus Torvalds 15861da177e4SLinus Torvalds out3: 15871da177e4SLinus Torvalds free_page(dev_page); 15881da177e4SLinus Torvalds out2: 15891da177e4SLinus Torvalds putname(dir_page); 15901da177e4SLinus Torvalds out1: 15911da177e4SLinus Torvalds free_page(type_page); 15921da177e4SLinus Torvalds return retval; 15931da177e4SLinus Torvalds } 15941da177e4SLinus Torvalds 15951da177e4SLinus Torvalds /* 15961da177e4SLinus Torvalds * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. 15971da177e4SLinus Torvalds * It can block. Requires the big lock held. 15981da177e4SLinus Torvalds */ 15991da177e4SLinus Torvalds void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, 16001da177e4SLinus Torvalds struct dentry *dentry) 16011da177e4SLinus Torvalds { 16021da177e4SLinus Torvalds struct dentry *old_root; 16031da177e4SLinus Torvalds struct vfsmount *old_rootmnt; 16041da177e4SLinus Torvalds write_lock(&fs->lock); 16051da177e4SLinus Torvalds old_root = fs->root; 16061da177e4SLinus Torvalds old_rootmnt = fs->rootmnt; 16071da177e4SLinus Torvalds fs->rootmnt = mntget(mnt); 16081da177e4SLinus Torvalds fs->root = dget(dentry); 16091da177e4SLinus Torvalds write_unlock(&fs->lock); 16101da177e4SLinus Torvalds if (old_root) { 16111da177e4SLinus Torvalds dput(old_root); 16121da177e4SLinus Torvalds mntput(old_rootmnt); 16131da177e4SLinus Torvalds } 16141da177e4SLinus Torvalds } 16151da177e4SLinus Torvalds 16161da177e4SLinus Torvalds /* 16171da177e4SLinus Torvalds * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. 16181da177e4SLinus Torvalds * It can block. Requires the big lock held. 16191da177e4SLinus Torvalds */ 16201da177e4SLinus Torvalds void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, 16211da177e4SLinus Torvalds struct dentry *dentry) 16221da177e4SLinus Torvalds { 16231da177e4SLinus Torvalds struct dentry *old_pwd; 16241da177e4SLinus Torvalds struct vfsmount *old_pwdmnt; 16251da177e4SLinus Torvalds 16261da177e4SLinus Torvalds write_lock(&fs->lock); 16271da177e4SLinus Torvalds old_pwd = fs->pwd; 16281da177e4SLinus Torvalds old_pwdmnt = fs->pwdmnt; 16291da177e4SLinus Torvalds fs->pwdmnt = mntget(mnt); 16301da177e4SLinus Torvalds fs->pwd = dget(dentry); 16311da177e4SLinus Torvalds write_unlock(&fs->lock); 16321da177e4SLinus Torvalds 16331da177e4SLinus Torvalds if (old_pwd) { 16341da177e4SLinus Torvalds dput(old_pwd); 16351da177e4SLinus Torvalds mntput(old_pwdmnt); 16361da177e4SLinus Torvalds } 16371da177e4SLinus Torvalds } 16381da177e4SLinus Torvalds 16391da177e4SLinus Torvalds static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) 16401da177e4SLinus Torvalds { 16411da177e4SLinus Torvalds struct task_struct *g, *p; 16421da177e4SLinus Torvalds struct fs_struct *fs; 16431da177e4SLinus Torvalds 16441da177e4SLinus Torvalds read_lock(&tasklist_lock); 16451da177e4SLinus Torvalds do_each_thread(g, p) { 16461da177e4SLinus Torvalds task_lock(p); 16471da177e4SLinus Torvalds fs = p->fs; 16481da177e4SLinus Torvalds if (fs) { 16491da177e4SLinus Torvalds atomic_inc(&fs->count); 16501da177e4SLinus Torvalds task_unlock(p); 1651b58fed8bSRam Pai if (fs->root == old_nd->dentry 1652b58fed8bSRam Pai && fs->rootmnt == old_nd->mnt) 16531da177e4SLinus Torvalds set_fs_root(fs, new_nd->mnt, new_nd->dentry); 1654b58fed8bSRam Pai if (fs->pwd == old_nd->dentry 1655b58fed8bSRam Pai && fs->pwdmnt == old_nd->mnt) 16561da177e4SLinus Torvalds set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); 16571da177e4SLinus Torvalds put_fs_struct(fs); 16581da177e4SLinus Torvalds } else 16591da177e4SLinus Torvalds task_unlock(p); 16601da177e4SLinus Torvalds } while_each_thread(g, p); 16611da177e4SLinus Torvalds read_unlock(&tasklist_lock); 16621da177e4SLinus Torvalds } 16631da177e4SLinus Torvalds 16641da177e4SLinus Torvalds /* 16651da177e4SLinus Torvalds * pivot_root Semantics: 16661da177e4SLinus Torvalds * Moves the root file system of the current process to the directory put_old, 16671da177e4SLinus Torvalds * makes new_root as the new root file system of the current process, and sets 16681da177e4SLinus Torvalds * root/cwd of all processes which had them on the current root to new_root. 16691da177e4SLinus Torvalds * 16701da177e4SLinus Torvalds * Restrictions: 16711da177e4SLinus Torvalds * The new_root and put_old must be directories, and must not be on the 16721da177e4SLinus Torvalds * same file system as the current process root. The put_old must be 16731da177e4SLinus Torvalds * underneath new_root, i.e. adding a non-zero number of /.. to the string 16741da177e4SLinus Torvalds * pointed to by put_old must yield the same directory as new_root. No other 16751da177e4SLinus Torvalds * file system may be mounted on put_old. After all, new_root is a mountpoint. 16761da177e4SLinus Torvalds * 16774a0d11faSNeil Brown * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. 16784a0d11faSNeil Brown * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives 16794a0d11faSNeil Brown * in this situation. 16804a0d11faSNeil Brown * 16811da177e4SLinus Torvalds * Notes: 16821da177e4SLinus Torvalds * - we don't move root/cwd if they are not at the root (reason: if something 16831da177e4SLinus Torvalds * cared enough to change them, it's probably wrong to force them elsewhere) 16841da177e4SLinus Torvalds * - it's okay to pick a root that isn't the root of a file system, e.g. 16851da177e4SLinus Torvalds * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, 16861da177e4SLinus Torvalds * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root 16871da177e4SLinus Torvalds * first. 16881da177e4SLinus Torvalds */ 1689b58fed8bSRam Pai asmlinkage long sys_pivot_root(const char __user * new_root, 1690b58fed8bSRam Pai const char __user * put_old) 16911da177e4SLinus Torvalds { 16921da177e4SLinus Torvalds struct vfsmount *tmp; 16931da177e4SLinus Torvalds struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; 16941da177e4SLinus Torvalds int error; 16951da177e4SLinus Torvalds 16961da177e4SLinus Torvalds if (!capable(CAP_SYS_ADMIN)) 16971da177e4SLinus Torvalds return -EPERM; 16981da177e4SLinus Torvalds 16991da177e4SLinus Torvalds lock_kernel(); 17001da177e4SLinus Torvalds 1701b58fed8bSRam Pai error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, 1702b58fed8bSRam Pai &new_nd); 17031da177e4SLinus Torvalds if (error) 17041da177e4SLinus Torvalds goto out0; 17051da177e4SLinus Torvalds error = -EINVAL; 17061da177e4SLinus Torvalds if (!check_mnt(new_nd.mnt)) 17071da177e4SLinus Torvalds goto out1; 17081da177e4SLinus Torvalds 17091da177e4SLinus Torvalds error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd); 17101da177e4SLinus Torvalds if (error) 17111da177e4SLinus Torvalds goto out1; 17121da177e4SLinus Torvalds 17131da177e4SLinus Torvalds error = security_sb_pivotroot(&old_nd, &new_nd); 17141da177e4SLinus Torvalds if (error) { 17151da177e4SLinus Torvalds path_release(&old_nd); 17161da177e4SLinus Torvalds goto out1; 17171da177e4SLinus Torvalds } 17181da177e4SLinus Torvalds 17191da177e4SLinus Torvalds read_lock(¤t->fs->lock); 17201da177e4SLinus Torvalds user_nd.mnt = mntget(current->fs->rootmnt); 17211da177e4SLinus Torvalds user_nd.dentry = dget(current->fs->root); 17221da177e4SLinus Torvalds read_unlock(¤t->fs->lock); 1723390c6843SRam Pai down_write(&namespace_sem); 17241b1dcc1bSJes Sorensen mutex_lock(&old_nd.dentry->d_inode->i_mutex); 17251da177e4SLinus Torvalds error = -EINVAL; 172621444403SRam Pai if (IS_MNT_SHARED(old_nd.mnt) || 172721444403SRam Pai IS_MNT_SHARED(new_nd.mnt->mnt_parent) || 172821444403SRam Pai IS_MNT_SHARED(user_nd.mnt->mnt_parent)) 172921444403SRam Pai goto out2; 17301da177e4SLinus Torvalds if (!check_mnt(user_nd.mnt)) 17311da177e4SLinus Torvalds goto out2; 17321da177e4SLinus Torvalds error = -ENOENT; 17331da177e4SLinus Torvalds if (IS_DEADDIR(new_nd.dentry->d_inode)) 17341da177e4SLinus Torvalds goto out2; 17351da177e4SLinus Torvalds if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) 17361da177e4SLinus Torvalds goto out2; 17371da177e4SLinus Torvalds if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) 17381da177e4SLinus Torvalds goto out2; 17391da177e4SLinus Torvalds error = -EBUSY; 17401da177e4SLinus Torvalds if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) 17411da177e4SLinus Torvalds goto out2; /* loop, on the same file system */ 17421da177e4SLinus Torvalds error = -EINVAL; 17431da177e4SLinus Torvalds if (user_nd.mnt->mnt_root != user_nd.dentry) 17441da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 17450bb6fcc1SMiklos Szeredi if (user_nd.mnt->mnt_parent == user_nd.mnt) 17460bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 17471da177e4SLinus Torvalds if (new_nd.mnt->mnt_root != new_nd.dentry) 17481da177e4SLinus Torvalds goto out2; /* not a mountpoint */ 17490bb6fcc1SMiklos Szeredi if (new_nd.mnt->mnt_parent == new_nd.mnt) 17500bb6fcc1SMiklos Szeredi goto out2; /* not attached */ 17511da177e4SLinus Torvalds tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ 17521da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 17531da177e4SLinus Torvalds if (tmp != new_nd.mnt) { 17541da177e4SLinus Torvalds for (;;) { 17551da177e4SLinus Torvalds if (tmp->mnt_parent == tmp) 17561da177e4SLinus Torvalds goto out3; /* already mounted on put_old */ 17571da177e4SLinus Torvalds if (tmp->mnt_parent == new_nd.mnt) 17581da177e4SLinus Torvalds break; 17591da177e4SLinus Torvalds tmp = tmp->mnt_parent; 17601da177e4SLinus Torvalds } 17611da177e4SLinus Torvalds if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) 17621da177e4SLinus Torvalds goto out3; 17631da177e4SLinus Torvalds } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) 17641da177e4SLinus Torvalds goto out3; 17651da177e4SLinus Torvalds detach_mnt(new_nd.mnt, &parent_nd); 17661da177e4SLinus Torvalds detach_mnt(user_nd.mnt, &root_parent); 17671da177e4SLinus Torvalds attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ 17681da177e4SLinus Torvalds attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ 17696b3286edSKirill Korotaev touch_mnt_namespace(current->nsproxy->mnt_ns); 17701da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 17711da177e4SLinus Torvalds chroot_fs_refs(&user_nd, &new_nd); 17721da177e4SLinus Torvalds security_sb_post_pivotroot(&user_nd, &new_nd); 17731da177e4SLinus Torvalds error = 0; 17741da177e4SLinus Torvalds path_release(&root_parent); 17751da177e4SLinus Torvalds path_release(&parent_nd); 17761da177e4SLinus Torvalds out2: 17771b1dcc1bSJes Sorensen mutex_unlock(&old_nd.dentry->d_inode->i_mutex); 1778390c6843SRam Pai up_write(&namespace_sem); 17791da177e4SLinus Torvalds path_release(&user_nd); 17801da177e4SLinus Torvalds path_release(&old_nd); 17811da177e4SLinus Torvalds out1: 17821da177e4SLinus Torvalds path_release(&new_nd); 17831da177e4SLinus Torvalds out0: 17841da177e4SLinus Torvalds unlock_kernel(); 17851da177e4SLinus Torvalds return error; 17861da177e4SLinus Torvalds out3: 17871da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 17881da177e4SLinus Torvalds goto out2; 17891da177e4SLinus Torvalds } 17901da177e4SLinus Torvalds 17911da177e4SLinus Torvalds static void __init init_mount_tree(void) 17921da177e4SLinus Torvalds { 17931da177e4SLinus Torvalds struct vfsmount *mnt; 17946b3286edSKirill Korotaev struct mnt_namespace *ns; 17951da177e4SLinus Torvalds 17961da177e4SLinus Torvalds mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); 17971da177e4SLinus Torvalds if (IS_ERR(mnt)) 17981da177e4SLinus Torvalds panic("Can't create rootfs"); 17996b3286edSKirill Korotaev ns = kmalloc(sizeof(*ns), GFP_KERNEL); 18006b3286edSKirill Korotaev if (!ns) 18011da177e4SLinus Torvalds panic("Can't allocate initial namespace"); 18026b3286edSKirill Korotaev atomic_set(&ns->count, 1); 18036b3286edSKirill Korotaev INIT_LIST_HEAD(&ns->list); 18046b3286edSKirill Korotaev init_waitqueue_head(&ns->poll); 18056b3286edSKirill Korotaev ns->event = 0; 18066b3286edSKirill Korotaev list_add(&mnt->mnt_list, &ns->list); 18076b3286edSKirill Korotaev ns->root = mnt; 18086b3286edSKirill Korotaev mnt->mnt_ns = ns; 18091da177e4SLinus Torvalds 18106b3286edSKirill Korotaev init_task.nsproxy->mnt_ns = ns; 18116b3286edSKirill Korotaev get_mnt_ns(ns); 18121da177e4SLinus Torvalds 18136b3286edSKirill Korotaev set_fs_pwd(current->fs, ns->root, ns->root->mnt_root); 18146b3286edSKirill Korotaev set_fs_root(current->fs, ns->root, ns->root->mnt_root); 18151da177e4SLinus Torvalds } 18161da177e4SLinus Torvalds 181774bf17cfSDenis Cheng void __init mnt_init(void) 18181da177e4SLinus Torvalds { 181913f14b4dSEric Dumazet unsigned u; 182015a67dd8SRandy Dunlap int err; 18211da177e4SLinus Torvalds 1822390c6843SRam Pai init_rwsem(&namespace_sem); 1823390c6843SRam Pai 18241da177e4SLinus Torvalds mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), 182520c2df83SPaul Mundt 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); 18261da177e4SLinus Torvalds 1827b58fed8bSRam Pai mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); 18281da177e4SLinus Torvalds 18291da177e4SLinus Torvalds if (!mount_hashtable) 18301da177e4SLinus Torvalds panic("Failed to allocate mount hash table\n"); 18311da177e4SLinus Torvalds 183213f14b4dSEric Dumazet printk("Mount-cache hash table entries: %lu\n", HASH_SIZE); 18331da177e4SLinus Torvalds 183413f14b4dSEric Dumazet for (u = 0; u < HASH_SIZE; u++) 183513f14b4dSEric Dumazet INIT_LIST_HEAD(&mount_hashtable[u]); 18361da177e4SLinus Torvalds 183715a67dd8SRandy Dunlap err = sysfs_init(); 183815a67dd8SRandy Dunlap if (err) 183915a67dd8SRandy Dunlap printk(KERN_WARNING "%s: sysfs_init error: %d\n", 184015a67dd8SRandy Dunlap __FUNCTION__, err); 184100d26666SGreg Kroah-Hartman fs_kobj = kobject_create_and_add("fs", NULL); 184200d26666SGreg Kroah-Hartman if (!fs_kobj) 184300d26666SGreg Kroah-Hartman printk(KERN_WARNING "%s: kobj create error\n", __FUNCTION__); 18441da177e4SLinus Torvalds init_rootfs(); 18451da177e4SLinus Torvalds init_mount_tree(); 18461da177e4SLinus Torvalds } 18471da177e4SLinus Torvalds 18486b3286edSKirill Korotaev void __put_mnt_ns(struct mnt_namespace *ns) 18491da177e4SLinus Torvalds { 18506b3286edSKirill Korotaev struct vfsmount *root = ns->root; 185170fbcdf4SRam Pai LIST_HEAD(umount_list); 18526b3286edSKirill Korotaev ns->root = NULL; 18531ce88cf4SMiklos Szeredi spin_unlock(&vfsmount_lock); 1854390c6843SRam Pai down_write(&namespace_sem); 18551da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 1856a05964f3SRam Pai umount_tree(root, 0, &umount_list); 18571da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 1858390c6843SRam Pai up_write(&namespace_sem); 185970fbcdf4SRam Pai release_mounts(&umount_list); 18606b3286edSKirill Korotaev kfree(ns); 18611da177e4SLinus Torvalds } 1862