2005-04-17 05:20:36 +07:00
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/*
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* linux/fs/namespace.c
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*
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* (C) Copyright Al Viro 2000, 2001
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* Released under GPL v2.
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*
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* Based on code from fs/super.c, copyright Linus Torvalds and others.
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* Heavily rewritten.
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*/
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#include <linux/config.h>
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#include <linux/syscalls.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/smp_lock.h>
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#include <linux/init.h>
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#include <linux/quotaops.h>
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#include <linux/acct.h>
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#include <linux/module.h>
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#include <linux/seq_file.h>
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#include <linux/namespace.h>
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#include <linux/namei.h>
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#include <linux/security.h>
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#include <linux/mount.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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extern int __init init_rootfs(void);
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#ifdef CONFIG_SYSFS
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extern int __init sysfs_init(void);
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#else
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static inline int sysfs_init(void)
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{
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return 0;
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}
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#endif
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/* spinlock for vfsmount related operations, inplace of dcache_lock */
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__cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
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static struct list_head *mount_hashtable;
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static int hash_mask, hash_bits;
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static kmem_cache_t *mnt_cache;
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static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
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{
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unsigned long tmp = ((unsigned long) mnt / L1_CACHE_BYTES);
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tmp += ((unsigned long) dentry / L1_CACHE_BYTES);
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tmp = tmp + (tmp >> hash_bits);
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return tmp & hash_mask;
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}
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struct vfsmount *alloc_vfsmnt(const char *name)
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{
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struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL);
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if (mnt) {
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memset(mnt, 0, sizeof(struct vfsmount));
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atomic_set(&mnt->mnt_count,1);
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INIT_LIST_HEAD(&mnt->mnt_hash);
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INIT_LIST_HEAD(&mnt->mnt_child);
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INIT_LIST_HEAD(&mnt->mnt_mounts);
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INIT_LIST_HEAD(&mnt->mnt_list);
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INIT_LIST_HEAD(&mnt->mnt_fslink);
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if (name) {
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int size = strlen(name)+1;
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char *newname = kmalloc(size, GFP_KERNEL);
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if (newname) {
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memcpy(newname, name, size);
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mnt->mnt_devname = newname;
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}
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}
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}
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return mnt;
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}
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void free_vfsmnt(struct vfsmount *mnt)
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{
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kfree(mnt->mnt_devname);
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kmem_cache_free(mnt_cache, mnt);
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}
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/*
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* Now, lookup_mnt increments the ref count before returning
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* the vfsmount struct.
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*/
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struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
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{
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struct list_head * head = mount_hashtable + hash(mnt, dentry);
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struct list_head * tmp = head;
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struct vfsmount *p, *found = NULL;
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spin_lock(&vfsmount_lock);
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for (;;) {
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tmp = tmp->next;
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p = NULL;
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if (tmp == head)
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break;
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p = list_entry(tmp, struct vfsmount, mnt_hash);
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if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) {
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found = mntget(p);
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break;
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}
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}
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spin_unlock(&vfsmount_lock);
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return found;
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}
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static inline int check_mnt(struct vfsmount *mnt)
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{
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return mnt->mnt_namespace == current->namespace;
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}
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static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd)
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{
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old_nd->dentry = mnt->mnt_mountpoint;
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old_nd->mnt = mnt->mnt_parent;
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mnt->mnt_parent = mnt;
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mnt->mnt_mountpoint = mnt->mnt_root;
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list_del_init(&mnt->mnt_child);
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list_del_init(&mnt->mnt_hash);
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old_nd->dentry->d_mounted--;
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}
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static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd)
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{
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mnt->mnt_parent = mntget(nd->mnt);
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mnt->mnt_mountpoint = dget(nd->dentry);
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list_add(&mnt->mnt_hash, mount_hashtable+hash(nd->mnt, nd->dentry));
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list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts);
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nd->dentry->d_mounted++;
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}
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static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root)
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{
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struct list_head *next = p->mnt_mounts.next;
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if (next == &p->mnt_mounts) {
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while (1) {
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if (p == root)
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return NULL;
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next = p->mnt_child.next;
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if (next != &p->mnt_parent->mnt_mounts)
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break;
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p = p->mnt_parent;
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}
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}
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return list_entry(next, struct vfsmount, mnt_child);
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}
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static struct vfsmount *
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clone_mnt(struct vfsmount *old, struct dentry *root)
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{
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struct super_block *sb = old->mnt_sb;
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struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
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if (mnt) {
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mnt->mnt_flags = old->mnt_flags;
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atomic_inc(&sb->s_active);
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mnt->mnt_sb = sb;
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mnt->mnt_root = dget(root);
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mnt->mnt_mountpoint = mnt->mnt_root;
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mnt->mnt_parent = mnt;
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mnt->mnt_namespace = old->mnt_namespace;
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/* stick the duplicate mount on the same expiry list
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* as the original if that was on one */
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spin_lock(&vfsmount_lock);
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if (!list_empty(&old->mnt_fslink))
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list_add(&mnt->mnt_fslink, &old->mnt_fslink);
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spin_unlock(&vfsmount_lock);
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}
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return mnt;
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}
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void __mntput(struct vfsmount *mnt)
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{
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struct super_block *sb = mnt->mnt_sb;
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dput(mnt->mnt_root);
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free_vfsmnt(mnt);
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deactivate_super(sb);
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}
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EXPORT_SYMBOL(__mntput);
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/* iterator */
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static void *m_start(struct seq_file *m, loff_t *pos)
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{
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struct namespace *n = m->private;
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struct list_head *p;
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loff_t l = *pos;
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down_read(&n->sem);
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list_for_each(p, &n->list)
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if (!l--)
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return list_entry(p, struct vfsmount, mnt_list);
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return NULL;
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}
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static void *m_next(struct seq_file *m, void *v, loff_t *pos)
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{
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struct namespace *n = m->private;
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struct list_head *p = ((struct vfsmount *)v)->mnt_list.next;
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(*pos)++;
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return p==&n->list ? NULL : list_entry(p, struct vfsmount, mnt_list);
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}
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static void m_stop(struct seq_file *m, void *v)
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{
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struct namespace *n = m->private;
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up_read(&n->sem);
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}
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static inline void mangle(struct seq_file *m, const char *s)
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{
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seq_escape(m, s, " \t\n\\");
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}
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static int show_vfsmnt(struct seq_file *m, void *v)
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{
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struct vfsmount *mnt = v;
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int err = 0;
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static struct proc_fs_info {
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int flag;
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char *str;
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} fs_info[] = {
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{ MS_SYNCHRONOUS, ",sync" },
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{ MS_DIRSYNC, ",dirsync" },
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{ MS_MANDLOCK, ",mand" },
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{ MS_NOATIME, ",noatime" },
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{ MS_NODIRATIME, ",nodiratime" },
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{ 0, NULL }
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};
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static struct proc_fs_info mnt_info[] = {
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{ MNT_NOSUID, ",nosuid" },
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{ MNT_NODEV, ",nodev" },
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{ MNT_NOEXEC, ",noexec" },
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{ 0, NULL }
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};
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struct proc_fs_info *fs_infop;
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mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
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seq_putc(m, ' ');
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seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
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seq_putc(m, ' ');
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mangle(m, mnt->mnt_sb->s_type->name);
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seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw");
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for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
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if (mnt->mnt_sb->s_flags & fs_infop->flag)
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seq_puts(m, fs_infop->str);
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}
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for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
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if (mnt->mnt_flags & fs_infop->flag)
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seq_puts(m, fs_infop->str);
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}
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if (mnt->mnt_sb->s_op->show_options)
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err = mnt->mnt_sb->s_op->show_options(m, mnt);
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seq_puts(m, " 0 0\n");
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return err;
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}
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struct seq_operations mounts_op = {
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.start = m_start,
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.next = m_next,
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.stop = m_stop,
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.show = show_vfsmnt
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};
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/**
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* may_umount_tree - check if a mount tree is busy
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* @mnt: root of mount tree
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*
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* This is called to check if a tree of mounts has any
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* open files, pwds, chroots or sub mounts that are
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* busy.
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*/
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int may_umount_tree(struct vfsmount *mnt)
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{
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struct list_head *next;
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struct vfsmount *this_parent = mnt;
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int actual_refs;
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int minimum_refs;
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spin_lock(&vfsmount_lock);
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actual_refs = atomic_read(&mnt->mnt_count);
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minimum_refs = 2;
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repeat:
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next = this_parent->mnt_mounts.next;
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resume:
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while (next != &this_parent->mnt_mounts) {
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struct vfsmount *p = list_entry(next, struct vfsmount, mnt_child);
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next = next->next;
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actual_refs += atomic_read(&p->mnt_count);
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minimum_refs += 2;
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if (!list_empty(&p->mnt_mounts)) {
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this_parent = p;
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goto repeat;
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}
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}
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if (this_parent != mnt) {
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next = this_parent->mnt_child.next;
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this_parent = this_parent->mnt_parent;
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goto resume;
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}
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spin_unlock(&vfsmount_lock);
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if (actual_refs > minimum_refs)
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return -EBUSY;
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return 0;
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}
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EXPORT_SYMBOL(may_umount_tree);
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/**
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* may_umount - check if a mount point is busy
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* @mnt: root of mount
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*
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* This is called to check if a mount point has any
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* open files, pwds, chroots or sub mounts. If the
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* mount has sub mounts this will return busy
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* regardless of whether the sub mounts are busy.
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*
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* Doesn't take quota and stuff into account. IOW, in some cases it will
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* give false negatives. The main reason why it's here is that we need
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* a non-destructive way to look for easily umountable filesystems.
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*/
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int may_umount(struct vfsmount *mnt)
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{
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if (atomic_read(&mnt->mnt_count) > 2)
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return -EBUSY;
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return 0;
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}
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EXPORT_SYMBOL(may_umount);
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2005-06-24 12:05:33 +07:00
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static void umount_tree(struct vfsmount *mnt)
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2005-04-17 05:20:36 +07:00
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{
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struct vfsmount *p;
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LIST_HEAD(kill);
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for (p = mnt; p; p = next_mnt(p, mnt)) {
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list_del(&p->mnt_list);
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list_add(&p->mnt_list, &kill);
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}
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while (!list_empty(&kill)) {
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mnt = list_entry(kill.next, struct vfsmount, mnt_list);
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list_del_init(&mnt->mnt_list);
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list_del_init(&mnt->mnt_fslink);
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if (mnt->mnt_parent == mnt) {
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spin_unlock(&vfsmount_lock);
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} else {
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struct nameidata old_nd;
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detach_mnt(mnt, &old_nd);
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spin_unlock(&vfsmount_lock);
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path_release(&old_nd);
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}
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mntput(mnt);
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spin_lock(&vfsmount_lock);
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|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
static int do_umount(struct vfsmount *mnt, int flags)
|
|
|
|
{
|
|
|
|
struct super_block * sb = mnt->mnt_sb;
|
|
|
|
int retval;
|
|
|
|
|
|
|
|
retval = security_sb_umount(mnt, flags);
|
|
|
|
if (retval)
|
|
|
|
return retval;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Allow userspace to request a mountpoint be expired rather than
|
|
|
|
* unmounting unconditionally. Unmount only happens if:
|
|
|
|
* (1) the mark is already set (the mark is cleared by mntput())
|
|
|
|
* (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
|
|
|
|
*/
|
|
|
|
if (flags & MNT_EXPIRE) {
|
|
|
|
if (mnt == current->fs->rootmnt ||
|
|
|
|
flags & (MNT_FORCE | MNT_DETACH))
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
if (atomic_read(&mnt->mnt_count) != 2)
|
|
|
|
return -EBUSY;
|
|
|
|
|
|
|
|
if (!xchg(&mnt->mnt_expiry_mark, 1))
|
|
|
|
return -EAGAIN;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* If we may have to abort operations to get out of this
|
|
|
|
* mount, and they will themselves hold resources we must
|
|
|
|
* allow the fs to do things. In the Unix tradition of
|
|
|
|
* 'Gee thats tricky lets do it in userspace' the umount_begin
|
|
|
|
* might fail to complete on the first run through as other tasks
|
|
|
|
* must return, and the like. Thats for the mount program to worry
|
|
|
|
* about for the moment.
|
|
|
|
*/
|
|
|
|
|
|
|
|
lock_kernel();
|
|
|
|
if( (flags&MNT_FORCE) && sb->s_op->umount_begin)
|
|
|
|
sb->s_op->umount_begin(sb);
|
|
|
|
unlock_kernel();
|
|
|
|
|
|
|
|
/*
|
|
|
|
* No sense to grab the lock for this test, but test itself looks
|
|
|
|
* somewhat bogus. Suggestions for better replacement?
|
|
|
|
* Ho-hum... In principle, we might treat that as umount + switch
|
|
|
|
* to rootfs. GC would eventually take care of the old vfsmount.
|
|
|
|
* Actually it makes sense, especially if rootfs would contain a
|
|
|
|
* /reboot - static binary that would close all descriptors and
|
|
|
|
* call reboot(9). Then init(8) could umount root and exec /reboot.
|
|
|
|
*/
|
|
|
|
if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) {
|
|
|
|
/*
|
|
|
|
* Special case for "unmounting" root ...
|
|
|
|
* we just try to remount it readonly.
|
|
|
|
*/
|
|
|
|
down_write(&sb->s_umount);
|
|
|
|
if (!(sb->s_flags & MS_RDONLY)) {
|
|
|
|
lock_kernel();
|
|
|
|
DQUOT_OFF(sb);
|
|
|
|
retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
|
|
|
|
unlock_kernel();
|
|
|
|
}
|
|
|
|
up_write(&sb->s_umount);
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
|
|
|
down_write(¤t->namespace->sem);
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
|
|
|
|
if (atomic_read(&sb->s_active) == 1) {
|
|
|
|
/* last instance - try to be smart */
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
lock_kernel();
|
|
|
|
DQUOT_OFF(sb);
|
|
|
|
acct_auto_close(sb);
|
|
|
|
unlock_kernel();
|
|
|
|
security_sb_umount_close(mnt);
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
}
|
|
|
|
retval = -EBUSY;
|
|
|
|
if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) {
|
|
|
|
if (!list_empty(&mnt->mnt_list))
|
|
|
|
umount_tree(mnt);
|
|
|
|
retval = 0;
|
|
|
|
}
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
if (retval)
|
|
|
|
security_sb_umount_busy(mnt);
|
|
|
|
up_write(¤t->namespace->sem);
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Now umount can handle mount points as well as block devices.
|
|
|
|
* This is important for filesystems which use unnamed block devices.
|
|
|
|
*
|
|
|
|
* We now support a flag for forced unmount like the other 'big iron'
|
|
|
|
* unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
|
|
|
|
*/
|
|
|
|
|
|
|
|
asmlinkage long sys_umount(char __user * name, int flags)
|
|
|
|
{
|
|
|
|
struct nameidata nd;
|
|
|
|
int retval;
|
|
|
|
|
|
|
|
retval = __user_walk(name, LOOKUP_FOLLOW, &nd);
|
|
|
|
if (retval)
|
|
|
|
goto out;
|
|
|
|
retval = -EINVAL;
|
|
|
|
if (nd.dentry != nd.mnt->mnt_root)
|
|
|
|
goto dput_and_out;
|
|
|
|
if (!check_mnt(nd.mnt))
|
|
|
|
goto dput_and_out;
|
|
|
|
|
|
|
|
retval = -EPERM;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
|
|
goto dput_and_out;
|
|
|
|
|
|
|
|
retval = do_umount(nd.mnt, flags);
|
|
|
|
dput_and_out:
|
|
|
|
path_release_on_umount(&nd);
|
|
|
|
out:
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
|
|
|
#ifdef __ARCH_WANT_SYS_OLDUMOUNT
|
|
|
|
|
|
|
|
/*
|
|
|
|
* The 2.0 compatible umount. No flags.
|
|
|
|
*/
|
|
|
|
|
|
|
|
asmlinkage long sys_oldumount(char __user * name)
|
|
|
|
{
|
|
|
|
return sys_umount(name,0);
|
|
|
|
}
|
|
|
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
static int mount_is_safe(struct nameidata *nd)
|
|
|
|
{
|
|
|
|
if (capable(CAP_SYS_ADMIN))
|
|
|
|
return 0;
|
|
|
|
return -EPERM;
|
|
|
|
#ifdef notyet
|
|
|
|
if (S_ISLNK(nd->dentry->d_inode->i_mode))
|
|
|
|
return -EPERM;
|
|
|
|
if (nd->dentry->d_inode->i_mode & S_ISVTX) {
|
|
|
|
if (current->uid != nd->dentry->d_inode->i_uid)
|
|
|
|
return -EPERM;
|
|
|
|
}
|
|
|
|
if (permission(nd->dentry->d_inode, MAY_WRITE, nd))
|
|
|
|
return -EPERM;
|
|
|
|
return 0;
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
|
|
|
|
static int
|
|
|
|
lives_below_in_same_fs(struct dentry *d, struct dentry *dentry)
|
|
|
|
{
|
|
|
|
while (1) {
|
|
|
|
if (d == dentry)
|
|
|
|
return 1;
|
|
|
|
if (d == NULL || d == d->d_parent)
|
|
|
|
return 0;
|
|
|
|
d = d->d_parent;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry)
|
|
|
|
{
|
|
|
|
struct vfsmount *res, *p, *q, *r, *s;
|
|
|
|
struct list_head *h;
|
|
|
|
struct nameidata nd;
|
|
|
|
|
|
|
|
res = q = clone_mnt(mnt, dentry);
|
|
|
|
if (!q)
|
|
|
|
goto Enomem;
|
|
|
|
q->mnt_mountpoint = mnt->mnt_mountpoint;
|
|
|
|
|
|
|
|
p = mnt;
|
|
|
|
for (h = mnt->mnt_mounts.next; h != &mnt->mnt_mounts; h = h->next) {
|
|
|
|
r = list_entry(h, struct vfsmount, mnt_child);
|
|
|
|
if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry))
|
|
|
|
continue;
|
|
|
|
|
|
|
|
for (s = r; s; s = next_mnt(s, r)) {
|
|
|
|
while (p != s->mnt_parent) {
|
|
|
|
p = p->mnt_parent;
|
|
|
|
q = q->mnt_parent;
|
|
|
|
}
|
|
|
|
p = s;
|
|
|
|
nd.mnt = q;
|
|
|
|
nd.dentry = p->mnt_mountpoint;
|
|
|
|
q = clone_mnt(p, p->mnt_root);
|
|
|
|
if (!q)
|
|
|
|
goto Enomem;
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
list_add_tail(&q->mnt_list, &res->mnt_list);
|
|
|
|
attach_mnt(q, &nd);
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
return res;
|
|
|
|
Enomem:
|
|
|
|
if (res) {
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
umount_tree(res);
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
}
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
|
|
|
|
{
|
|
|
|
int err;
|
|
|
|
if (mnt->mnt_sb->s_flags & MS_NOUSER)
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
|
|
|
|
S_ISDIR(mnt->mnt_root->d_inode->i_mode))
|
|
|
|
return -ENOTDIR;
|
|
|
|
|
|
|
|
err = -ENOENT;
|
|
|
|
down(&nd->dentry->d_inode->i_sem);
|
|
|
|
if (IS_DEADDIR(nd->dentry->d_inode))
|
|
|
|
goto out_unlock;
|
|
|
|
|
|
|
|
err = security_sb_check_sb(mnt, nd);
|
|
|
|
if (err)
|
|
|
|
goto out_unlock;
|
|
|
|
|
|
|
|
err = -ENOENT;
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) {
|
|
|
|
struct list_head head;
|
|
|
|
|
|
|
|
attach_mnt(mnt, nd);
|
|
|
|
list_add_tail(&head, &mnt->mnt_list);
|
|
|
|
list_splice(&head, current->namespace->list.prev);
|
|
|
|
mntget(mnt);
|
|
|
|
err = 0;
|
|
|
|
}
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
out_unlock:
|
|
|
|
up(&nd->dentry->d_inode->i_sem);
|
|
|
|
if (!err)
|
|
|
|
security_sb_post_addmount(mnt, nd);
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* do loopback mount.
|
|
|
|
*/
|
|
|
|
static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
|
|
|
|
{
|
|
|
|
struct nameidata old_nd;
|
|
|
|
struct vfsmount *mnt = NULL;
|
|
|
|
int err = mount_is_safe(nd);
|
|
|
|
if (err)
|
|
|
|
return err;
|
|
|
|
if (!old_name || !*old_name)
|
|
|
|
return -EINVAL;
|
|
|
|
err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
|
|
|
|
if (err)
|
|
|
|
return err;
|
|
|
|
|
|
|
|
down_write(¤t->namespace->sem);
|
|
|
|
err = -EINVAL;
|
|
|
|
if (check_mnt(nd->mnt) && (!recurse || check_mnt(old_nd.mnt))) {
|
|
|
|
err = -ENOMEM;
|
|
|
|
if (recurse)
|
|
|
|
mnt = copy_tree(old_nd.mnt, old_nd.dentry);
|
|
|
|
else
|
|
|
|
mnt = clone_mnt(old_nd.mnt, old_nd.dentry);
|
|
|
|
}
|
|
|
|
|
|
|
|
if (mnt) {
|
|
|
|
/* stop bind mounts from expiring */
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
list_del_init(&mnt->mnt_fslink);
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
|
|
|
|
err = graft_tree(mnt, nd);
|
|
|
|
if (err) {
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
umount_tree(mnt);
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
} else
|
|
|
|
mntput(mnt);
|
|
|
|
}
|
|
|
|
|
|
|
|
up_write(¤t->namespace->sem);
|
|
|
|
path_release(&old_nd);
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* change filesystem flags. dir should be a physical root of filesystem.
|
|
|
|
* If you've mounted a non-root directory somewhere and want to do remount
|
|
|
|
* on it - tough luck.
|
|
|
|
*/
|
|
|
|
|
|
|
|
static int do_remount(struct nameidata *nd, int flags, int mnt_flags,
|
|
|
|
void *data)
|
|
|
|
{
|
|
|
|
int err;
|
|
|
|
struct super_block * sb = nd->mnt->mnt_sb;
|
|
|
|
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
|
|
return -EPERM;
|
|
|
|
|
|
|
|
if (!check_mnt(nd->mnt))
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
if (nd->dentry != nd->mnt->mnt_root)
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
down_write(&sb->s_umount);
|
|
|
|
err = do_remount_sb(sb, flags, data, 0);
|
|
|
|
if (!err)
|
|
|
|
nd->mnt->mnt_flags=mnt_flags;
|
|
|
|
up_write(&sb->s_umount);
|
|
|
|
if (!err)
|
|
|
|
security_sb_post_remount(nd->mnt, flags, data);
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int do_move_mount(struct nameidata *nd, char *old_name)
|
|
|
|
{
|
|
|
|
struct nameidata old_nd, parent_nd;
|
|
|
|
struct vfsmount *p;
|
|
|
|
int err = 0;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
|
|
return -EPERM;
|
|
|
|
if (!old_name || !*old_name)
|
|
|
|
return -EINVAL;
|
|
|
|
err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
|
|
|
|
if (err)
|
|
|
|
return err;
|
|
|
|
|
|
|
|
down_write(¤t->namespace->sem);
|
|
|
|
while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
|
|
|
|
;
|
|
|
|
err = -EINVAL;
|
|
|
|
if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
|
|
|
|
goto out;
|
|
|
|
|
|
|
|
err = -ENOENT;
|
|
|
|
down(&nd->dentry->d_inode->i_sem);
|
|
|
|
if (IS_DEADDIR(nd->dentry->d_inode))
|
|
|
|
goto out1;
|
|
|
|
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry))
|
|
|
|
goto out2;
|
|
|
|
|
|
|
|
err = -EINVAL;
|
|
|
|
if (old_nd.dentry != old_nd.mnt->mnt_root)
|
|
|
|
goto out2;
|
|
|
|
|
|
|
|
if (old_nd.mnt == old_nd.mnt->mnt_parent)
|
|
|
|
goto out2;
|
|
|
|
|
|
|
|
if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
|
|
|
|
S_ISDIR(old_nd.dentry->d_inode->i_mode))
|
|
|
|
goto out2;
|
|
|
|
|
|
|
|
err = -ELOOP;
|
|
|
|
for (p = nd->mnt; p->mnt_parent!=p; p = p->mnt_parent)
|
|
|
|
if (p == old_nd.mnt)
|
|
|
|
goto out2;
|
|
|
|
err = 0;
|
|
|
|
|
|
|
|
detach_mnt(old_nd.mnt, &parent_nd);
|
|
|
|
attach_mnt(old_nd.mnt, nd);
|
|
|
|
|
|
|
|
/* if the mount is moved, it should no longer be expire
|
|
|
|
* automatically */
|
|
|
|
list_del_init(&old_nd.mnt->mnt_fslink);
|
|
|
|
out2:
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
out1:
|
|
|
|
up(&nd->dentry->d_inode->i_sem);
|
|
|
|
out:
|
|
|
|
up_write(¤t->namespace->sem);
|
|
|
|
if (!err)
|
|
|
|
path_release(&parent_nd);
|
|
|
|
path_release(&old_nd);
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* create a new mount for userspace and request it to be added into the
|
|
|
|
* namespace's tree
|
|
|
|
*/
|
|
|
|
static int do_new_mount(struct nameidata *nd, char *type, int flags,
|
|
|
|
int mnt_flags, char *name, void *data)
|
|
|
|
{
|
|
|
|
struct vfsmount *mnt;
|
|
|
|
|
|
|
|
if (!type || !memchr(type, 0, PAGE_SIZE))
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
/* we need capabilities... */
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
|
|
return -EPERM;
|
|
|
|
|
|
|
|
mnt = do_kern_mount(type, flags, name, data);
|
|
|
|
if (IS_ERR(mnt))
|
|
|
|
return PTR_ERR(mnt);
|
|
|
|
|
|
|
|
return do_add_mount(mnt, nd, mnt_flags, NULL);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* add a mount into a namespace's mount tree
|
|
|
|
* - provide the option of adding the new mount to an expiration list
|
|
|
|
*/
|
|
|
|
int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
|
|
|
|
int mnt_flags, struct list_head *fslist)
|
|
|
|
{
|
|
|
|
int err;
|
|
|
|
|
|
|
|
down_write(¤t->namespace->sem);
|
|
|
|
/* Something was mounted here while we slept */
|
|
|
|
while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
|
|
|
|
;
|
|
|
|
err = -EINVAL;
|
|
|
|
if (!check_mnt(nd->mnt))
|
|
|
|
goto unlock;
|
|
|
|
|
|
|
|
/* Refuse the same filesystem on the same mount point */
|
|
|
|
err = -EBUSY;
|
|
|
|
if (nd->mnt->mnt_sb == newmnt->mnt_sb &&
|
|
|
|
nd->mnt->mnt_root == nd->dentry)
|
|
|
|
goto unlock;
|
|
|
|
|
|
|
|
err = -EINVAL;
|
|
|
|
if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
|
|
|
|
goto unlock;
|
|
|
|
|
|
|
|
newmnt->mnt_flags = mnt_flags;
|
|
|
|
err = graft_tree(newmnt, nd);
|
|
|
|
|
|
|
|
if (err == 0 && fslist) {
|
|
|
|
/* add to the specified expiration list */
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
list_add_tail(&newmnt->mnt_fslink, fslist);
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
}
|
|
|
|
|
|
|
|
unlock:
|
|
|
|
up_write(¤t->namespace->sem);
|
|
|
|
mntput(newmnt);
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
EXPORT_SYMBOL_GPL(do_add_mount);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* process a list of expirable mountpoints with the intent of discarding any
|
|
|
|
* mountpoints that aren't in use and haven't been touched since last we came
|
|
|
|
* here
|
|
|
|
*/
|
|
|
|
void mark_mounts_for_expiry(struct list_head *mounts)
|
|
|
|
{
|
|
|
|
struct namespace *namespace;
|
|
|
|
struct vfsmount *mnt, *next;
|
|
|
|
LIST_HEAD(graveyard);
|
|
|
|
|
|
|
|
if (list_empty(mounts))
|
|
|
|
return;
|
|
|
|
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
|
|
|
|
/* extract from the expiration list every vfsmount that matches the
|
|
|
|
* following criteria:
|
|
|
|
* - only referenced by its parent vfsmount
|
|
|
|
* - still marked for expiry (marked on the last call here; marks are
|
|
|
|
* cleared by mntput())
|
|
|
|
*/
|
|
|
|
list_for_each_entry_safe(mnt, next, mounts, mnt_fslink) {
|
|
|
|
if (!xchg(&mnt->mnt_expiry_mark, 1) ||
|
|
|
|
atomic_read(&mnt->mnt_count) != 1)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
mntget(mnt);
|
|
|
|
list_move(&mnt->mnt_fslink, &graveyard);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* go through the vfsmounts we've just consigned to the graveyard to
|
|
|
|
* - check that they're still dead
|
|
|
|
* - delete the vfsmount from the appropriate namespace under lock
|
|
|
|
* - dispose of the corpse
|
|
|
|
*/
|
|
|
|
while (!list_empty(&graveyard)) {
|
|
|
|
mnt = list_entry(graveyard.next, struct vfsmount, mnt_fslink);
|
|
|
|
list_del_init(&mnt->mnt_fslink);
|
|
|
|
|
|
|
|
/* don't do anything if the namespace is dead - all the
|
|
|
|
* vfsmounts from it are going away anyway */
|
|
|
|
namespace = mnt->mnt_namespace;
|
|
|
|
if (!namespace || atomic_read(&namespace->count) <= 0)
|
|
|
|
continue;
|
|
|
|
get_namespace(namespace);
|
|
|
|
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
down_write(&namespace->sem);
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
|
|
|
|
/* check that it is still dead: the count should now be 2 - as
|
|
|
|
* contributed by the vfsmount parent and the mntget above */
|
|
|
|
if (atomic_read(&mnt->mnt_count) == 2) {
|
|
|
|
struct vfsmount *xdmnt;
|
|
|
|
struct dentry *xdentry;
|
|
|
|
|
|
|
|
/* delete from the namespace */
|
|
|
|
list_del_init(&mnt->mnt_list);
|
|
|
|
list_del_init(&mnt->mnt_child);
|
|
|
|
list_del_init(&mnt->mnt_hash);
|
|
|
|
mnt->mnt_mountpoint->d_mounted--;
|
|
|
|
|
|
|
|
xdentry = mnt->mnt_mountpoint;
|
|
|
|
mnt->mnt_mountpoint = mnt->mnt_root;
|
|
|
|
xdmnt = mnt->mnt_parent;
|
|
|
|
mnt->mnt_parent = mnt;
|
|
|
|
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
|
|
|
|
mntput(xdmnt);
|
|
|
|
dput(xdentry);
|
|
|
|
|
|
|
|
/* now lay it to rest if this was the last ref on the
|
|
|
|
* superblock */
|
|
|
|
if (atomic_read(&mnt->mnt_sb->s_active) == 1) {
|
|
|
|
/* last instance - try to be smart */
|
|
|
|
lock_kernel();
|
|
|
|
DQUOT_OFF(mnt->mnt_sb);
|
|
|
|
acct_auto_close(mnt->mnt_sb);
|
|
|
|
unlock_kernel();
|
|
|
|
}
|
|
|
|
|
|
|
|
mntput(mnt);
|
|
|
|
} else {
|
|
|
|
/* someone brought it back to life whilst we didn't
|
|
|
|
* have any locks held so return it to the expiration
|
|
|
|
* list */
|
|
|
|
list_add_tail(&mnt->mnt_fslink, mounts);
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
}
|
|
|
|
|
|
|
|
up_write(&namespace->sem);
|
|
|
|
|
|
|
|
mntput(mnt);
|
|
|
|
put_namespace(namespace);
|
|
|
|
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
}
|
|
|
|
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
}
|
|
|
|
|
|
|
|
EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Some copy_from_user() implementations do not return the exact number of
|
|
|
|
* bytes remaining to copy on a fault. But copy_mount_options() requires that.
|
|
|
|
* Note that this function differs from copy_from_user() in that it will oops
|
|
|
|
* on bad values of `to', rather than returning a short copy.
|
|
|
|
*/
|
|
|
|
static long
|
|
|
|
exact_copy_from_user(void *to, const void __user *from, unsigned long n)
|
|
|
|
{
|
|
|
|
char *t = to;
|
|
|
|
const char __user *f = from;
|
|
|
|
char c;
|
|
|
|
|
|
|
|
if (!access_ok(VERIFY_READ, from, n))
|
|
|
|
return n;
|
|
|
|
|
|
|
|
while (n) {
|
|
|
|
if (__get_user(c, f)) {
|
|
|
|
memset(t, 0, n);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
*t++ = c;
|
|
|
|
f++;
|
|
|
|
n--;
|
|
|
|
}
|
|
|
|
return n;
|
|
|
|
}
|
|
|
|
|
|
|
|
int copy_mount_options(const void __user *data, unsigned long *where)
|
|
|
|
{
|
|
|
|
int i;
|
|
|
|
unsigned long page;
|
|
|
|
unsigned long size;
|
|
|
|
|
|
|
|
*where = 0;
|
|
|
|
if (!data)
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
if (!(page = __get_free_page(GFP_KERNEL)))
|
|
|
|
return -ENOMEM;
|
|
|
|
|
|
|
|
/* We only care that *some* data at the address the user
|
|
|
|
* gave us is valid. Just in case, we'll zero
|
|
|
|
* the remainder of the page.
|
|
|
|
*/
|
|
|
|
/* copy_from_user cannot cross TASK_SIZE ! */
|
|
|
|
size = TASK_SIZE - (unsigned long)data;
|
|
|
|
if (size > PAGE_SIZE)
|
|
|
|
size = PAGE_SIZE;
|
|
|
|
|
|
|
|
i = size - exact_copy_from_user((void *)page, data, size);
|
|
|
|
if (!i) {
|
|
|
|
free_page(page);
|
|
|
|
return -EFAULT;
|
|
|
|
}
|
|
|
|
if (i != PAGE_SIZE)
|
|
|
|
memset((char *)page + i, 0, PAGE_SIZE - i);
|
|
|
|
*where = page;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
|
|
|
|
* be given to the mount() call (ie: read-only, no-dev, no-suid etc).
|
|
|
|
*
|
|
|
|
* data is a (void *) that can point to any structure up to
|
|
|
|
* PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
|
|
|
|
* information (or be NULL).
|
|
|
|
*
|
|
|
|
* Pre-0.97 versions of mount() didn't have a flags word.
|
|
|
|
* When the flags word was introduced its top half was required
|
|
|
|
* to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
|
|
|
|
* Therefore, if this magic number is present, it carries no information
|
|
|
|
* and must be discarded.
|
|
|
|
*/
|
|
|
|
long do_mount(char * dev_name, char * dir_name, char *type_page,
|
|
|
|
unsigned long flags, void *data_page)
|
|
|
|
{
|
|
|
|
struct nameidata nd;
|
|
|
|
int retval = 0;
|
|
|
|
int mnt_flags = 0;
|
|
|
|
|
|
|
|
/* Discard magic */
|
|
|
|
if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
|
|
|
|
flags &= ~MS_MGC_MSK;
|
|
|
|
|
|
|
|
/* Basic sanity checks */
|
|
|
|
|
|
|
|
if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
|
|
|
|
return -EINVAL;
|
|
|
|
if (dev_name && !memchr(dev_name, 0, PAGE_SIZE))
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
if (data_page)
|
|
|
|
((char *)data_page)[PAGE_SIZE - 1] = 0;
|
|
|
|
|
|
|
|
/* Separate the per-mountpoint flags */
|
|
|
|
if (flags & MS_NOSUID)
|
|
|
|
mnt_flags |= MNT_NOSUID;
|
|
|
|
if (flags & MS_NODEV)
|
|
|
|
mnt_flags |= MNT_NODEV;
|
|
|
|
if (flags & MS_NOEXEC)
|
|
|
|
mnt_flags |= MNT_NOEXEC;
|
|
|
|
flags &= ~(MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_ACTIVE);
|
|
|
|
|
|
|
|
/* ... and get the mountpoint */
|
|
|
|
retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
|
|
|
|
if (retval)
|
|
|
|
return retval;
|
|
|
|
|
|
|
|
retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page);
|
|
|
|
if (retval)
|
|
|
|
goto dput_out;
|
|
|
|
|
|
|
|
if (flags & MS_REMOUNT)
|
|
|
|
retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags,
|
|
|
|
data_page);
|
|
|
|
else if (flags & MS_BIND)
|
|
|
|
retval = do_loopback(&nd, dev_name, flags & MS_REC);
|
|
|
|
else if (flags & MS_MOVE)
|
|
|
|
retval = do_move_mount(&nd, dev_name);
|
|
|
|
else
|
|
|
|
retval = do_new_mount(&nd, type_page, flags, mnt_flags,
|
|
|
|
dev_name, data_page);
|
|
|
|
dput_out:
|
|
|
|
path_release(&nd);
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
|
|
|
int copy_namespace(int flags, struct task_struct *tsk)
|
|
|
|
{
|
|
|
|
struct namespace *namespace = tsk->namespace;
|
|
|
|
struct namespace *new_ns;
|
|
|
|
struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL;
|
|
|
|
struct fs_struct *fs = tsk->fs;
|
|
|
|
struct vfsmount *p, *q;
|
|
|
|
|
|
|
|
if (!namespace)
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
get_namespace(namespace);
|
|
|
|
|
|
|
|
if (!(flags & CLONE_NEWNS))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
if (!capable(CAP_SYS_ADMIN)) {
|
|
|
|
put_namespace(namespace);
|
|
|
|
return -EPERM;
|
|
|
|
}
|
|
|
|
|
|
|
|
new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL);
|
|
|
|
if (!new_ns)
|
|
|
|
goto out;
|
|
|
|
|
|
|
|
atomic_set(&new_ns->count, 1);
|
|
|
|
init_rwsem(&new_ns->sem);
|
|
|
|
INIT_LIST_HEAD(&new_ns->list);
|
|
|
|
|
|
|
|
down_write(&tsk->namespace->sem);
|
|
|
|
/* First pass: copy the tree topology */
|
|
|
|
new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root);
|
|
|
|
if (!new_ns->root) {
|
|
|
|
up_write(&tsk->namespace->sem);
|
|
|
|
kfree(new_ns);
|
|
|
|
goto out;
|
|
|
|
}
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Second pass: switch the tsk->fs->* elements and mark new vfsmounts
|
|
|
|
* as belonging to new namespace. We have already acquired a private
|
|
|
|
* fs_struct, so tsk->fs->lock is not needed.
|
|
|
|
*/
|
|
|
|
p = namespace->root;
|
|
|
|
q = new_ns->root;
|
|
|
|
while (p) {
|
|
|
|
q->mnt_namespace = new_ns;
|
|
|
|
if (fs) {
|
|
|
|
if (p == fs->rootmnt) {
|
|
|
|
rootmnt = p;
|
|
|
|
fs->rootmnt = mntget(q);
|
|
|
|
}
|
|
|
|
if (p == fs->pwdmnt) {
|
|
|
|
pwdmnt = p;
|
|
|
|
fs->pwdmnt = mntget(q);
|
|
|
|
}
|
|
|
|
if (p == fs->altrootmnt) {
|
|
|
|
altrootmnt = p;
|
|
|
|
fs->altrootmnt = mntget(q);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
p = next_mnt(p, namespace->root);
|
|
|
|
q = next_mnt(q, new_ns->root);
|
|
|
|
}
|
|
|
|
up_write(&tsk->namespace->sem);
|
|
|
|
|
|
|
|
tsk->namespace = new_ns;
|
|
|
|
|
|
|
|
if (rootmnt)
|
|
|
|
mntput(rootmnt);
|
|
|
|
if (pwdmnt)
|
|
|
|
mntput(pwdmnt);
|
|
|
|
if (altrootmnt)
|
|
|
|
mntput(altrootmnt);
|
|
|
|
|
|
|
|
put_namespace(namespace);
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
out:
|
|
|
|
put_namespace(namespace);
|
|
|
|
return -ENOMEM;
|
|
|
|
}
|
|
|
|
|
|
|
|
asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name,
|
|
|
|
char __user * type, unsigned long flags,
|
|
|
|
void __user * data)
|
|
|
|
{
|
|
|
|
int retval;
|
|
|
|
unsigned long data_page;
|
|
|
|
unsigned long type_page;
|
|
|
|
unsigned long dev_page;
|
|
|
|
char *dir_page;
|
|
|
|
|
|
|
|
retval = copy_mount_options (type, &type_page);
|
|
|
|
if (retval < 0)
|
|
|
|
return retval;
|
|
|
|
|
|
|
|
dir_page = getname(dir_name);
|
|
|
|
retval = PTR_ERR(dir_page);
|
|
|
|
if (IS_ERR(dir_page))
|
|
|
|
goto out1;
|
|
|
|
|
|
|
|
retval = copy_mount_options (dev_name, &dev_page);
|
|
|
|
if (retval < 0)
|
|
|
|
goto out2;
|
|
|
|
|
|
|
|
retval = copy_mount_options (data, &data_page);
|
|
|
|
if (retval < 0)
|
|
|
|
goto out3;
|
|
|
|
|
|
|
|
lock_kernel();
|
|
|
|
retval = do_mount((char*)dev_page, dir_page, (char*)type_page,
|
|
|
|
flags, (void*)data_page);
|
|
|
|
unlock_kernel();
|
|
|
|
free_page(data_page);
|
|
|
|
|
|
|
|
out3:
|
|
|
|
free_page(dev_page);
|
|
|
|
out2:
|
|
|
|
putname(dir_page);
|
|
|
|
out1:
|
|
|
|
free_page(type_page);
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
|
|
|
|
* It can block. Requires the big lock held.
|
|
|
|
*/
|
|
|
|
void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt,
|
|
|
|
struct dentry *dentry)
|
|
|
|
{
|
|
|
|
struct dentry *old_root;
|
|
|
|
struct vfsmount *old_rootmnt;
|
|
|
|
write_lock(&fs->lock);
|
|
|
|
old_root = fs->root;
|
|
|
|
old_rootmnt = fs->rootmnt;
|
|
|
|
fs->rootmnt = mntget(mnt);
|
|
|
|
fs->root = dget(dentry);
|
|
|
|
write_unlock(&fs->lock);
|
|
|
|
if (old_root) {
|
|
|
|
dput(old_root);
|
|
|
|
mntput(old_rootmnt);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
|
|
|
|
* It can block. Requires the big lock held.
|
|
|
|
*/
|
|
|
|
void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt,
|
|
|
|
struct dentry *dentry)
|
|
|
|
{
|
|
|
|
struct dentry *old_pwd;
|
|
|
|
struct vfsmount *old_pwdmnt;
|
|
|
|
|
|
|
|
write_lock(&fs->lock);
|
|
|
|
old_pwd = fs->pwd;
|
|
|
|
old_pwdmnt = fs->pwdmnt;
|
|
|
|
fs->pwdmnt = mntget(mnt);
|
|
|
|
fs->pwd = dget(dentry);
|
|
|
|
write_unlock(&fs->lock);
|
|
|
|
|
|
|
|
if (old_pwd) {
|
|
|
|
dput(old_pwd);
|
|
|
|
mntput(old_pwdmnt);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
|
|
|
|
{
|
|
|
|
struct task_struct *g, *p;
|
|
|
|
struct fs_struct *fs;
|
|
|
|
|
|
|
|
read_lock(&tasklist_lock);
|
|
|
|
do_each_thread(g, p) {
|
|
|
|
task_lock(p);
|
|
|
|
fs = p->fs;
|
|
|
|
if (fs) {
|
|
|
|
atomic_inc(&fs->count);
|
|
|
|
task_unlock(p);
|
|
|
|
if (fs->root==old_nd->dentry&&fs->rootmnt==old_nd->mnt)
|
|
|
|
set_fs_root(fs, new_nd->mnt, new_nd->dentry);
|
|
|
|
if (fs->pwd==old_nd->dentry&&fs->pwdmnt==old_nd->mnt)
|
|
|
|
set_fs_pwd(fs, new_nd->mnt, new_nd->dentry);
|
|
|
|
put_fs_struct(fs);
|
|
|
|
} else
|
|
|
|
task_unlock(p);
|
|
|
|
} while_each_thread(g, p);
|
|
|
|
read_unlock(&tasklist_lock);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* pivot_root Semantics:
|
|
|
|
* Moves the root file system of the current process to the directory put_old,
|
|
|
|
* makes new_root as the new root file system of the current process, and sets
|
|
|
|
* root/cwd of all processes which had them on the current root to new_root.
|
|
|
|
*
|
|
|
|
* Restrictions:
|
|
|
|
* The new_root and put_old must be directories, and must not be on the
|
|
|
|
* same file system as the current process root. The put_old must be
|
|
|
|
* underneath new_root, i.e. adding a non-zero number of /.. to the string
|
|
|
|
* pointed to by put_old must yield the same directory as new_root. No other
|
|
|
|
* file system may be mounted on put_old. After all, new_root is a mountpoint.
|
|
|
|
*
|
|
|
|
* Notes:
|
|
|
|
* - we don't move root/cwd if they are not at the root (reason: if something
|
|
|
|
* cared enough to change them, it's probably wrong to force them elsewhere)
|
|
|
|
* - it's okay to pick a root that isn't the root of a file system, e.g.
|
|
|
|
* /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
|
|
|
|
* though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
|
|
|
|
* first.
|
|
|
|
*/
|
|
|
|
|
|
|
|
asmlinkage long sys_pivot_root(const char __user *new_root, const char __user *put_old)
|
|
|
|
{
|
|
|
|
struct vfsmount *tmp;
|
|
|
|
struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd;
|
|
|
|
int error;
|
|
|
|
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
|
|
return -EPERM;
|
|
|
|
|
|
|
|
lock_kernel();
|
|
|
|
|
|
|
|
error = __user_walk(new_root, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &new_nd);
|
|
|
|
if (error)
|
|
|
|
goto out0;
|
|
|
|
error = -EINVAL;
|
|
|
|
if (!check_mnt(new_nd.mnt))
|
|
|
|
goto out1;
|
|
|
|
|
|
|
|
error = __user_walk(put_old, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &old_nd);
|
|
|
|
if (error)
|
|
|
|
goto out1;
|
|
|
|
|
|
|
|
error = security_sb_pivotroot(&old_nd, &new_nd);
|
|
|
|
if (error) {
|
|
|
|
path_release(&old_nd);
|
|
|
|
goto out1;
|
|
|
|
}
|
|
|
|
|
|
|
|
read_lock(¤t->fs->lock);
|
|
|
|
user_nd.mnt = mntget(current->fs->rootmnt);
|
|
|
|
user_nd.dentry = dget(current->fs->root);
|
|
|
|
read_unlock(¤t->fs->lock);
|
|
|
|
down_write(¤t->namespace->sem);
|
|
|
|
down(&old_nd.dentry->d_inode->i_sem);
|
|
|
|
error = -EINVAL;
|
|
|
|
if (!check_mnt(user_nd.mnt))
|
|
|
|
goto out2;
|
|
|
|
error = -ENOENT;
|
|
|
|
if (IS_DEADDIR(new_nd.dentry->d_inode))
|
|
|
|
goto out2;
|
|
|
|
if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry))
|
|
|
|
goto out2;
|
|
|
|
if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry))
|
|
|
|
goto out2;
|
|
|
|
error = -EBUSY;
|
|
|
|
if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt)
|
|
|
|
goto out2; /* loop, on the same file system */
|
|
|
|
error = -EINVAL;
|
|
|
|
if (user_nd.mnt->mnt_root != user_nd.dentry)
|
|
|
|
goto out2; /* not a mountpoint */
|
|
|
|
if (new_nd.mnt->mnt_root != new_nd.dentry)
|
|
|
|
goto out2; /* not a mountpoint */
|
|
|
|
tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
if (tmp != new_nd.mnt) {
|
|
|
|
for (;;) {
|
|
|
|
if (tmp->mnt_parent == tmp)
|
|
|
|
goto out3; /* already mounted on put_old */
|
|
|
|
if (tmp->mnt_parent == new_nd.mnt)
|
|
|
|
break;
|
|
|
|
tmp = tmp->mnt_parent;
|
|
|
|
}
|
|
|
|
if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry))
|
|
|
|
goto out3;
|
|
|
|
} else if (!is_subdir(old_nd.dentry, new_nd.dentry))
|
|
|
|
goto out3;
|
|
|
|
detach_mnt(new_nd.mnt, &parent_nd);
|
|
|
|
detach_mnt(user_nd.mnt, &root_parent);
|
|
|
|
attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */
|
|
|
|
attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
chroot_fs_refs(&user_nd, &new_nd);
|
|
|
|
security_sb_post_pivotroot(&user_nd, &new_nd);
|
|
|
|
error = 0;
|
|
|
|
path_release(&root_parent);
|
|
|
|
path_release(&parent_nd);
|
|
|
|
out2:
|
|
|
|
up(&old_nd.dentry->d_inode->i_sem);
|
|
|
|
up_write(¤t->namespace->sem);
|
|
|
|
path_release(&user_nd);
|
|
|
|
path_release(&old_nd);
|
|
|
|
out1:
|
|
|
|
path_release(&new_nd);
|
|
|
|
out0:
|
|
|
|
unlock_kernel();
|
|
|
|
return error;
|
|
|
|
out3:
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
goto out2;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void __init init_mount_tree(void)
|
|
|
|
{
|
|
|
|
struct vfsmount *mnt;
|
|
|
|
struct namespace *namespace;
|
|
|
|
struct task_struct *g, *p;
|
|
|
|
|
|
|
|
mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
|
|
|
|
if (IS_ERR(mnt))
|
|
|
|
panic("Can't create rootfs");
|
|
|
|
namespace = kmalloc(sizeof(*namespace), GFP_KERNEL);
|
|
|
|
if (!namespace)
|
|
|
|
panic("Can't allocate initial namespace");
|
|
|
|
atomic_set(&namespace->count, 1);
|
|
|
|
INIT_LIST_HEAD(&namespace->list);
|
|
|
|
init_rwsem(&namespace->sem);
|
|
|
|
list_add(&mnt->mnt_list, &namespace->list);
|
|
|
|
namespace->root = mnt;
|
|
|
|
mnt->mnt_namespace = namespace;
|
|
|
|
|
|
|
|
init_task.namespace = namespace;
|
|
|
|
read_lock(&tasklist_lock);
|
|
|
|
do_each_thread(g, p) {
|
|
|
|
get_namespace(namespace);
|
|
|
|
p->namespace = namespace;
|
|
|
|
} while_each_thread(g, p);
|
|
|
|
read_unlock(&tasklist_lock);
|
|
|
|
|
|
|
|
set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root);
|
|
|
|
set_fs_root(current->fs, namespace->root, namespace->root->mnt_root);
|
|
|
|
}
|
|
|
|
|
|
|
|
void __init mnt_init(unsigned long mempages)
|
|
|
|
{
|
|
|
|
struct list_head *d;
|
|
|
|
unsigned int nr_hash;
|
|
|
|
int i;
|
|
|
|
|
|
|
|
mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
|
|
|
|
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
|
|
|
|
|
|
|
|
mount_hashtable = (struct list_head *)
|
|
|
|
__get_free_page(GFP_ATOMIC);
|
|
|
|
|
|
|
|
if (!mount_hashtable)
|
|
|
|
panic("Failed to allocate mount hash table\n");
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Find the power-of-two list-heads that can fit into the allocation..
|
|
|
|
* We don't guarantee that "sizeof(struct list_head)" is necessarily
|
|
|
|
* a power-of-two.
|
|
|
|
*/
|
|
|
|
nr_hash = PAGE_SIZE / sizeof(struct list_head);
|
|
|
|
hash_bits = 0;
|
|
|
|
do {
|
|
|
|
hash_bits++;
|
|
|
|
} while ((nr_hash >> hash_bits) != 0);
|
|
|
|
hash_bits--;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Re-calculate the actual number of entries and the mask
|
|
|
|
* from the number of bits we can fit.
|
|
|
|
*/
|
|
|
|
nr_hash = 1UL << hash_bits;
|
|
|
|
hash_mask = nr_hash-1;
|
|
|
|
|
|
|
|
printk("Mount-cache hash table entries: %d\n", nr_hash);
|
|
|
|
|
|
|
|
/* And initialize the newly allocated array */
|
|
|
|
d = mount_hashtable;
|
|
|
|
i = nr_hash;
|
|
|
|
do {
|
|
|
|
INIT_LIST_HEAD(d);
|
|
|
|
d++;
|
|
|
|
i--;
|
|
|
|
} while (i);
|
|
|
|
sysfs_init();
|
|
|
|
init_rootfs();
|
|
|
|
init_mount_tree();
|
|
|
|
}
|
|
|
|
|
|
|
|
void __put_namespace(struct namespace *namespace)
|
|
|
|
{
|
|
|
|
struct vfsmount *mnt;
|
|
|
|
|
|
|
|
down_write(&namespace->sem);
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
|
|
|
|
list_for_each_entry(mnt, &namespace->list, mnt_list) {
|
|
|
|
mnt->mnt_namespace = NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
umount_tree(namespace->root);
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
|
|
up_write(&namespace->sem);
|
|
|
|
kfree(namespace);
|
|
|
|
}
|