mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-06 00:16:39 +07:00
f13b83580a
The Coverity checker spotted the following bug in dup_namespace(): <-- snip --> if (!new_ns->root) { up_write(&namespace_sem); kfree(new_ns); goto out; } ... out: return new_ns; <-- snip --> Callers expect a non-NULL result to not be freed. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1766 lines
44 KiB
C
1766 lines
44 KiB
C
/*
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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/capability.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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#include "pnode.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 int event;
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static struct list_head *mount_hashtable;
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static int hash_mask __read_mostly, hash_bits __read_mostly;
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static kmem_cache_t *mnt_cache;
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static struct rw_semaphore namespace_sem;
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/* /sys/fs */
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decl_subsys(fs, NULL, NULL);
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EXPORT_SYMBOL_GPL(fs_subsys);
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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_expire);
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INIT_LIST_HEAD(&mnt->mnt_share);
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INIT_LIST_HEAD(&mnt->mnt_slave_list);
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INIT_LIST_HEAD(&mnt->mnt_slave);
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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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* find the first or last mount at @dentry on vfsmount @mnt depending on
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* @dir. If @dir is set return the first mount else return the last mount.
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*/
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struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry,
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int dir)
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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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for (;;) {
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tmp = dir ? tmp->next : tmp->prev;
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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 = p;
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break;
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}
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}
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return found;
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}
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/*
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* 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 vfsmount *child_mnt;
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spin_lock(&vfsmount_lock);
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if ((child_mnt = __lookup_mnt(mnt, dentry, 1)))
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mntget(child_mnt);
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spin_unlock(&vfsmount_lock);
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return child_mnt;
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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 touch_namespace(struct namespace *ns)
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{
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if (ns) {
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ns->event = ++event;
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wake_up_interruptible(&ns->poll);
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}
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}
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static void __touch_namespace(struct namespace *ns)
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{
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if (ns && ns->event != event) {
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ns->event = event;
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wake_up_interruptible(&ns->poll);
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}
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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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void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
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struct vfsmount *child_mnt)
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{
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child_mnt->mnt_parent = mntget(mnt);
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child_mnt->mnt_mountpoint = dget(dentry);
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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_set_mountpoint(nd->mnt, nd->dentry, mnt);
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list_add_tail(&mnt->mnt_hash, mount_hashtable +
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hash(nd->mnt, nd->dentry));
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list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts);
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}
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/*
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* the caller must hold vfsmount_lock
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*/
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static void commit_tree(struct vfsmount *mnt)
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{
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struct vfsmount *parent = mnt->mnt_parent;
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struct vfsmount *m;
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LIST_HEAD(head);
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struct namespace *n = parent->mnt_namespace;
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BUG_ON(parent == mnt);
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list_add_tail(&head, &mnt->mnt_list);
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list_for_each_entry(m, &head, mnt_list)
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m->mnt_namespace = n;
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list_splice(&head, n->list.prev);
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list_add_tail(&mnt->mnt_hash, mount_hashtable +
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hash(parent, mnt->mnt_mountpoint));
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list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
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touch_namespace(n);
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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 *skip_mnt_tree(struct vfsmount *p)
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{
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struct list_head *prev = p->mnt_mounts.prev;
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while (prev != &p->mnt_mounts) {
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p = list_entry(prev, struct vfsmount, mnt_child);
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prev = p->mnt_mounts.prev;
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}
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return p;
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}
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static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
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int flag)
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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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if (flag & CL_SLAVE) {
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list_add(&mnt->mnt_slave, &old->mnt_slave_list);
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mnt->mnt_master = old;
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CLEAR_MNT_SHARED(mnt);
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} else {
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if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
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list_add(&mnt->mnt_share, &old->mnt_share);
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if (IS_MNT_SLAVE(old))
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list_add(&mnt->mnt_slave, &old->mnt_slave);
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mnt->mnt_master = old->mnt_master;
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}
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if (flag & CL_MAKE_SHARED)
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set_mnt_shared(mnt);
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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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if (flag & CL_EXPIRE) {
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spin_lock(&vfsmount_lock);
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if (!list_empty(&old->mnt_expire))
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list_add(&mnt->mnt_expire, &old->mnt_expire);
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spin_unlock(&vfsmount_lock);
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}
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}
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return mnt;
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}
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static inline 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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void mntput_no_expire(struct vfsmount *mnt)
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{
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repeat:
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if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) {
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if (likely(!mnt->mnt_pinned)) {
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spin_unlock(&vfsmount_lock);
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__mntput(mnt);
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return;
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}
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atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count);
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mnt->mnt_pinned = 0;
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spin_unlock(&vfsmount_lock);
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acct_auto_close_mnt(mnt);
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security_sb_umount_close(mnt);
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goto repeat;
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}
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}
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EXPORT_SYMBOL(mntput_no_expire);
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void mnt_pin(struct vfsmount *mnt)
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{
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spin_lock(&vfsmount_lock);
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mnt->mnt_pinned++;
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spin_unlock(&vfsmount_lock);
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}
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EXPORT_SYMBOL(mnt_pin);
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void mnt_unpin(struct vfsmount *mnt)
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{
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spin_lock(&vfsmount_lock);
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if (mnt->mnt_pinned) {
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atomic_inc(&mnt->mnt_count);
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mnt->mnt_pinned--;
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}
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spin_unlock(&vfsmount_lock);
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}
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EXPORT_SYMBOL(mnt_unpin);
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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(&namespace_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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up_read(&namespace_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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{ 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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{ MNT_NOATIME, ",noatime" },
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{ MNT_NODIRATIME, ",nodiratime" },
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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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int actual_refs = 0;
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int minimum_refs = 0;
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struct vfsmount *p;
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spin_lock(&vfsmount_lock);
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for (p = mnt; p; p = next_mnt(p, mnt)) {
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actual_refs += atomic_read(&p->mnt_count);
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minimum_refs += 2;
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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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int ret = 0;
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spin_lock(&vfsmount_lock);
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if (propagate_mount_busy(mnt, 2))
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ret = -EBUSY;
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spin_unlock(&vfsmount_lock);
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return ret;
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}
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EXPORT_SYMBOL(may_umount);
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|
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void release_mounts(struct list_head *head)
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{
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struct vfsmount *mnt;
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while (!list_empty(head)) {
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mnt = list_entry(head->next, struct vfsmount, mnt_hash);
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list_del_init(&mnt->mnt_hash);
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if (mnt->mnt_parent != mnt) {
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struct dentry *dentry;
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struct vfsmount *m;
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spin_lock(&vfsmount_lock);
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dentry = mnt->mnt_mountpoint;
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m = mnt->mnt_parent;
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mnt->mnt_mountpoint = mnt->mnt_root;
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mnt->mnt_parent = mnt;
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spin_unlock(&vfsmount_lock);
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dput(dentry);
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mntput(m);
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}
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mntput(mnt);
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}
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}
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|
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void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
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{
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struct vfsmount *p;
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for (p = mnt; p; p = next_mnt(p, mnt)) {
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list_del(&p->mnt_hash);
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list_add(&p->mnt_hash, kill);
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}
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|
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if (propagate)
|
|
propagate_umount(kill);
|
|
|
|
list_for_each_entry(p, kill, mnt_hash) {
|
|
list_del_init(&p->mnt_expire);
|
|
list_del_init(&p->mnt_list);
|
|
__touch_namespace(p->mnt_namespace);
|
|
p->mnt_namespace = NULL;
|
|
list_del_init(&p->mnt_child);
|
|
if (p->mnt_parent != p)
|
|
p->mnt_mountpoint->d_mounted--;
|
|
change_mnt_propagation(p, MS_PRIVATE);
|
|
}
|
|
}
|
|
|
|
static int do_umount(struct vfsmount *mnt, int flags)
|
|
{
|
|
struct super_block *sb = mnt->mnt_sb;
|
|
int retval;
|
|
LIST_HEAD(umount_list);
|
|
|
|
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(&namespace_sem);
|
|
spin_lock(&vfsmount_lock);
|
|
event++;
|
|
|
|
retval = -EBUSY;
|
|
if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) {
|
|
if (!list_empty(&mnt->mnt_list))
|
|
umount_tree(mnt, 1, &umount_list);
|
|
retval = 0;
|
|
}
|
|
spin_unlock(&vfsmount_lock);
|
|
if (retval)
|
|
security_sb_umount_busy(mnt);
|
|
up_write(&namespace_sem);
|
|
release_mounts(&umount_list);
|
|
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 (vfs_permission(nd, MAY_WRITE))
|
|
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;
|
|
}
|
|
}
|
|
|
|
struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
|
|
int flag)
|
|
{
|
|
struct vfsmount *res, *p, *q, *r, *s;
|
|
struct nameidata nd;
|
|
|
|
if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
|
|
return NULL;
|
|
|
|
res = q = clone_mnt(mnt, dentry, flag);
|
|
if (!q)
|
|
goto Enomem;
|
|
q->mnt_mountpoint = mnt->mnt_mountpoint;
|
|
|
|
p = mnt;
|
|
list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
|
|
if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry))
|
|
continue;
|
|
|
|
for (s = r; s; s = next_mnt(s, r)) {
|
|
if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) {
|
|
s = skip_mnt_tree(s);
|
|
continue;
|
|
}
|
|
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, flag);
|
|
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) {
|
|
LIST_HEAD(umount_list);
|
|
spin_lock(&vfsmount_lock);
|
|
umount_tree(res, 0, &umount_list);
|
|
spin_unlock(&vfsmount_lock);
|
|
release_mounts(&umount_list);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* @source_mnt : mount tree to be attached
|
|
* @nd : place the mount tree @source_mnt is attached
|
|
* @parent_nd : if non-null, detach the source_mnt from its parent and
|
|
* store the parent mount and mountpoint dentry.
|
|
* (done when source_mnt is moved)
|
|
*
|
|
* NOTE: in the table below explains the semantics when a source mount
|
|
* of a given type is attached to a destination mount of a given type.
|
|
* ---------------------------------------------------------------------------
|
|
* | BIND MOUNT OPERATION |
|
|
* |**************************************************************************
|
|
* | source-->| shared | private | slave | unbindable |
|
|
* | dest | | | | |
|
|
* | | | | | | |
|
|
* | v | | | | |
|
|
* |**************************************************************************
|
|
* | shared | shared (++) | shared (+) | shared(+++)| invalid |
|
|
* | | | | | |
|
|
* |non-shared| shared (+) | private | slave (*) | invalid |
|
|
* ***************************************************************************
|
|
* A bind operation clones the source mount and mounts the clone on the
|
|
* destination mount.
|
|
*
|
|
* (++) the cloned mount is propagated to all the mounts in the propagation
|
|
* tree of the destination mount and the cloned mount is added to
|
|
* the peer group of the source mount.
|
|
* (+) the cloned mount is created under the destination mount and is marked
|
|
* as shared. The cloned mount is added to the peer group of the source
|
|
* mount.
|
|
* (+++) the mount is propagated to all the mounts in the propagation tree
|
|
* of the destination mount and the cloned mount is made slave
|
|
* of the same master as that of the source mount. The cloned mount
|
|
* is marked as 'shared and slave'.
|
|
* (*) the cloned mount is made a slave of the same master as that of the
|
|
* source mount.
|
|
*
|
|
* ---------------------------------------------------------------------------
|
|
* | MOVE MOUNT OPERATION |
|
|
* |**************************************************************************
|
|
* | source-->| shared | private | slave | unbindable |
|
|
* | dest | | | | |
|
|
* | | | | | | |
|
|
* | v | | | | |
|
|
* |**************************************************************************
|
|
* | shared | shared (+) | shared (+) | shared(+++) | invalid |
|
|
* | | | | | |
|
|
* |non-shared| shared (+*) | private | slave (*) | unbindable |
|
|
* ***************************************************************************
|
|
*
|
|
* (+) the mount is moved to the destination. And is then propagated to
|
|
* all the mounts in the propagation tree of the destination mount.
|
|
* (+*) the mount is moved to the destination.
|
|
* (+++) the mount is moved to the destination and is then propagated to
|
|
* all the mounts belonging to the destination mount's propagation tree.
|
|
* the mount is marked as 'shared and slave'.
|
|
* (*) the mount continues to be a slave at the new location.
|
|
*
|
|
* if the source mount is a tree, the operations explained above is
|
|
* applied to each mount in the tree.
|
|
* Must be called without spinlocks held, since this function can sleep
|
|
* in allocations.
|
|
*/
|
|
static int attach_recursive_mnt(struct vfsmount *source_mnt,
|
|
struct nameidata *nd, struct nameidata *parent_nd)
|
|
{
|
|
LIST_HEAD(tree_list);
|
|
struct vfsmount *dest_mnt = nd->mnt;
|
|
struct dentry *dest_dentry = nd->dentry;
|
|
struct vfsmount *child, *p;
|
|
|
|
if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list))
|
|
return -EINVAL;
|
|
|
|
if (IS_MNT_SHARED(dest_mnt)) {
|
|
for (p = source_mnt; p; p = next_mnt(p, source_mnt))
|
|
set_mnt_shared(p);
|
|
}
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
if (parent_nd) {
|
|
detach_mnt(source_mnt, parent_nd);
|
|
attach_mnt(source_mnt, nd);
|
|
touch_namespace(current->namespace);
|
|
} else {
|
|
mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
|
|
commit_tree(source_mnt);
|
|
}
|
|
|
|
list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
|
|
list_del_init(&child->mnt_hash);
|
|
commit_tree(child);
|
|
}
|
|
spin_unlock(&vfsmount_lock);
|
|
return 0;
|
|
}
|
|
|
|
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;
|
|
mutex_lock(&nd->dentry->d_inode->i_mutex);
|
|
if (IS_DEADDIR(nd->dentry->d_inode))
|
|
goto out_unlock;
|
|
|
|
err = security_sb_check_sb(mnt, nd);
|
|
if (err)
|
|
goto out_unlock;
|
|
|
|
err = -ENOENT;
|
|
if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry))
|
|
err = attach_recursive_mnt(mnt, nd, NULL);
|
|
out_unlock:
|
|
mutex_unlock(&nd->dentry->d_inode->i_mutex);
|
|
if (!err)
|
|
security_sb_post_addmount(mnt, nd);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* recursively change the type of the mountpoint.
|
|
*/
|
|
static int do_change_type(struct nameidata *nd, int flag)
|
|
{
|
|
struct vfsmount *m, *mnt = nd->mnt;
|
|
int recurse = flag & MS_REC;
|
|
int type = flag & ~MS_REC;
|
|
|
|
if (nd->dentry != nd->mnt->mnt_root)
|
|
return -EINVAL;
|
|
|
|
down_write(&namespace_sem);
|
|
spin_lock(&vfsmount_lock);
|
|
for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
|
|
change_mnt_propagation(m, type);
|
|
spin_unlock(&vfsmount_lock);
|
|
up_write(&namespace_sem);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* 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(&namespace_sem);
|
|
err = -EINVAL;
|
|
if (IS_MNT_UNBINDABLE(old_nd.mnt))
|
|
goto out;
|
|
|
|
if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
|
|
goto out;
|
|
|
|
err = -ENOMEM;
|
|
if (recurse)
|
|
mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0);
|
|
else
|
|
mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0);
|
|
|
|
if (!mnt)
|
|
goto out;
|
|
|
|
err = graft_tree(mnt, nd);
|
|
if (err) {
|
|
LIST_HEAD(umount_list);
|
|
spin_lock(&vfsmount_lock);
|
|
umount_tree(mnt, 0, &umount_list);
|
|
spin_unlock(&vfsmount_lock);
|
|
release_mounts(&umount_list);
|
|
}
|
|
|
|
out:
|
|
up_write(&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 inline int tree_contains_unbindable(struct vfsmount *mnt)
|
|
{
|
|
struct vfsmount *p;
|
|
for (p = mnt; p; p = next_mnt(p, mnt)) {
|
|
if (IS_MNT_UNBINDABLE(p))
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
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(&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;
|
|
mutex_lock(&nd->dentry->d_inode->i_mutex);
|
|
if (IS_DEADDIR(nd->dentry->d_inode))
|
|
goto out1;
|
|
|
|
if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry))
|
|
goto out1;
|
|
|
|
err = -EINVAL;
|
|
if (old_nd.dentry != old_nd.mnt->mnt_root)
|
|
goto out1;
|
|
|
|
if (old_nd.mnt == old_nd.mnt->mnt_parent)
|
|
goto out1;
|
|
|
|
if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
|
|
S_ISDIR(old_nd.dentry->d_inode->i_mode))
|
|
goto out1;
|
|
/*
|
|
* Don't move a mount residing in a shared parent.
|
|
*/
|
|
if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent))
|
|
goto out1;
|
|
/*
|
|
* Don't move a mount tree containing unbindable mounts to a destination
|
|
* mount which is shared.
|
|
*/
|
|
if (IS_MNT_SHARED(nd->mnt) && tree_contains_unbindable(old_nd.mnt))
|
|
goto out1;
|
|
err = -ELOOP;
|
|
for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent)
|
|
if (p == old_nd.mnt)
|
|
goto out1;
|
|
|
|
if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd)))
|
|
goto out1;
|
|
|
|
spin_lock(&vfsmount_lock);
|
|
/* if the mount is moved, it should no longer be expire
|
|
* automatically */
|
|
list_del_init(&old_nd.mnt->mnt_expire);
|
|
spin_unlock(&vfsmount_lock);
|
|
out1:
|
|
mutex_unlock(&nd->dentry->d_inode->i_mutex);
|
|
out:
|
|
up_write(&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(&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;
|
|
if ((err = graft_tree(newmnt, nd)))
|
|
goto unlock;
|
|
|
|
if (fslist) {
|
|
/* add to the specified expiration list */
|
|
spin_lock(&vfsmount_lock);
|
|
list_add_tail(&newmnt->mnt_expire, fslist);
|
|
spin_unlock(&vfsmount_lock);
|
|
}
|
|
up_write(&namespace_sem);
|
|
return 0;
|
|
|
|
unlock:
|
|
up_write(&namespace_sem);
|
|
mntput(newmnt);
|
|
return err;
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(do_add_mount);
|
|
|
|
static void expire_mount(struct vfsmount *mnt, struct list_head *mounts,
|
|
struct list_head *umounts)
|
|
{
|
|
spin_lock(&vfsmount_lock);
|
|
|
|
/*
|
|
* Check if mount is still attached, if not, let whoever holds it deal
|
|
* with the sucker
|
|
*/
|
|
if (mnt->mnt_parent == mnt) {
|
|
spin_unlock(&vfsmount_lock);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Check that it is still dead: the count should now be 2 - as
|
|
* contributed by the vfsmount parent and the mntget above
|
|
*/
|
|
if (!propagate_mount_busy(mnt, 2)) {
|
|
/* delete from the namespace */
|
|
touch_namespace(mnt->mnt_namespace);
|
|
list_del_init(&mnt->mnt_list);
|
|
mnt->mnt_namespace = NULL;
|
|
umount_tree(mnt, 1, umounts);
|
|
spin_unlock(&vfsmount_lock);
|
|
} 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_expire, mounts);
|
|
spin_unlock(&vfsmount_lock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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_expire) {
|
|
if (!xchg(&mnt->mnt_expiry_mark, 1) ||
|
|
atomic_read(&mnt->mnt_count) != 1)
|
|
continue;
|
|
|
|
mntget(mnt);
|
|
list_move(&mnt->mnt_expire, &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)) {
|
|
LIST_HEAD(umounts);
|
|
mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire);
|
|
list_del_init(&mnt->mnt_expire);
|
|
|
|
/* don't do anything if the namespace is dead - all the
|
|
* vfsmounts from it are going away anyway */
|
|
namespace = mnt->mnt_namespace;
|
|
if (!namespace || !namespace->root)
|
|
continue;
|
|
get_namespace(namespace);
|
|
|
|
spin_unlock(&vfsmount_lock);
|
|
down_write(&namespace_sem);
|
|
expire_mount(mnt, mounts, &umounts);
|
|
up_write(&namespace_sem);
|
|
release_mounts(&umounts);
|
|
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;
|
|
if (flags & MS_NOATIME)
|
|
mnt_flags |= MNT_NOATIME;
|
|
if (flags & MS_NODIRATIME)
|
|
mnt_flags |= MNT_NODIRATIME;
|
|
|
|
flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
|
|
MS_NOATIME | MS_NODIRATIME);
|
|
|
|
/* ... 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_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
|
|
retval = do_change_type(&nd, flags);
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* Allocate a new namespace structure and populate it with contents
|
|
* copied from the namespace of the passed in task structure.
|
|
*/
|
|
struct namespace *dup_namespace(struct task_struct *tsk, struct fs_struct *fs)
|
|
{
|
|
struct namespace *namespace = tsk->namespace;
|
|
struct namespace *new_ns;
|
|
struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL;
|
|
struct vfsmount *p, *q;
|
|
|
|
new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL);
|
|
if (!new_ns)
|
|
return NULL;
|
|
|
|
atomic_set(&new_ns->count, 1);
|
|
INIT_LIST_HEAD(&new_ns->list);
|
|
init_waitqueue_head(&new_ns->poll);
|
|
new_ns->event = 0;
|
|
|
|
down_write(&namespace_sem);
|
|
/* First pass: copy the tree topology */
|
|
new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root,
|
|
CL_COPY_ALL | CL_EXPIRE);
|
|
if (!new_ns->root) {
|
|
up_write(&namespace_sem);
|
|
kfree(new_ns);
|
|
return NULL;
|
|
}
|
|
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(&namespace_sem);
|
|
|
|
if (rootmnt)
|
|
mntput(rootmnt);
|
|
if (pwdmnt)
|
|
mntput(pwdmnt);
|
|
if (altrootmnt)
|
|
mntput(altrootmnt);
|
|
|
|
return new_ns;
|
|
}
|
|
|
|
int copy_namespace(int flags, struct task_struct *tsk)
|
|
{
|
|
struct namespace *namespace = tsk->namespace;
|
|
struct namespace *new_ns;
|
|
int err = 0;
|
|
|
|
if (!namespace)
|
|
return 0;
|
|
|
|
get_namespace(namespace);
|
|
|
|
if (!(flags & CLONE_NEWNS))
|
|
return 0;
|
|
|
|
if (!capable(CAP_SYS_ADMIN)) {
|
|
err = -EPERM;
|
|
goto out;
|
|
}
|
|
|
|
new_ns = dup_namespace(tsk, tsk->fs);
|
|
if (!new_ns) {
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
tsk->namespace = new_ns;
|
|
|
|
out:
|
|
put_namespace(namespace);
|
|
return err;
|
|
}
|
|
|
|
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.
|
|
*
|
|
* Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
|
|
* See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
|
|
* in this situation.
|
|
*
|
|
* 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(&namespace_sem);
|
|
mutex_lock(&old_nd.dentry->d_inode->i_mutex);
|
|
error = -EINVAL;
|
|
if (IS_MNT_SHARED(old_nd.mnt) ||
|
|
IS_MNT_SHARED(new_nd.mnt->mnt_parent) ||
|
|
IS_MNT_SHARED(user_nd.mnt->mnt_parent))
|
|
goto out2;
|
|
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 (user_nd.mnt->mnt_parent == user_nd.mnt)
|
|
goto out2; /* not attached */
|
|
if (new_nd.mnt->mnt_root != new_nd.dentry)
|
|
goto out2; /* not a mountpoint */
|
|
if (new_nd.mnt->mnt_parent == new_nd.mnt)
|
|
goto out2; /* not attached */
|
|
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 / */
|
|
touch_namespace(current->namespace);
|
|
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:
|
|
mutex_unlock(&old_nd.dentry->d_inode->i_mutex);
|
|
up_write(&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_waitqueue_head(&namespace->poll);
|
|
namespace->event = 0;
|
|
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;
|
|
|
|
init_rwsem(&namespace_sem);
|
|
|
|
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();
|
|
subsystem_register(&fs_subsys);
|
|
init_rootfs();
|
|
init_mount_tree();
|
|
}
|
|
|
|
void __put_namespace(struct namespace *namespace)
|
|
{
|
|
struct vfsmount *root = namespace->root;
|
|
LIST_HEAD(umount_list);
|
|
namespace->root = NULL;
|
|
spin_unlock(&vfsmount_lock);
|
|
down_write(&namespace_sem);
|
|
spin_lock(&vfsmount_lock);
|
|
umount_tree(root, 0, &umount_list);
|
|
spin_unlock(&vfsmount_lock);
|
|
up_write(&namespace_sem);
|
|
release_mounts(&umount_list);
|
|
kfree(namespace);
|
|
}
|