+++ /dev/null
-/*
- * linux/fs/namespace.c
- *
- * (C) Copyright Al Viro 2000, 2001
- * Released under GPL v2.
- *
- * Based on code from fs/super.c, copyright Linus Torvalds and others.
- * Heavily rewritten.
- */
-
-#include <linux/config.h>
-#include <linux/syscalls.h>
-#include <linux/slab.h>
-#include <linux/sched.h>
-#include <linux/smp_lock.h>
-#include <linux/init.h>
-#include <linux/quotaops.h>
-#include <linux/acct.h>
-#include <linux/module.h>
-#include <linux/seq_file.h>
-#include <linux/namespace.h>
-#include <linux/namei.h>
-#include <linux/security.h>
-#include <linux/mount.h>
-#include <linux/vserver/namespace.h>
-#include <linux/vserver/xid.h>
-
-#include <asm/uaccess.h>
-#include <asm/unistd.h>
-
-extern int __init init_rootfs(void);
-
-#ifdef CONFIG_SYSFS
-extern int __init sysfs_init(void);
-#else
-static inline int sysfs_init(void)
-{
- return 0;
-}
-#endif
-
-/* spinlock for vfsmount related operations, inplace of dcache_lock */
- __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
-
-static struct list_head *mount_hashtable;
-static int hash_mask, hash_bits;
-static kmem_cache_t *mnt_cache;
-
-static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
-{
- unsigned long tmp = ((unsigned long) mnt / L1_CACHE_BYTES);
- tmp += ((unsigned long) dentry / L1_CACHE_BYTES);
- tmp = tmp + (tmp >> hash_bits);
- return tmp & hash_mask;
-}
-
-struct vfsmount *alloc_vfsmnt(const char *name)
-{
- struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL);
- if (mnt) {
- memset(mnt, 0, sizeof(struct vfsmount));
- atomic_set(&mnt->mnt_count,1);
- INIT_LIST_HEAD(&mnt->mnt_hash);
- INIT_LIST_HEAD(&mnt->mnt_child);
- INIT_LIST_HEAD(&mnt->mnt_mounts);
- INIT_LIST_HEAD(&mnt->mnt_list);
- INIT_LIST_HEAD(&mnt->mnt_fslink);
- if (name) {
- int size = strlen(name)+1;
- char *newname = kmalloc(size, GFP_KERNEL);
- if (newname) {
- memcpy(newname, name, size);
- mnt->mnt_devname = newname;
- }
- }
- }
- return mnt;
-}
-
-void free_vfsmnt(struct vfsmount *mnt)
-{
- kfree(mnt->mnt_devname);
- kmem_cache_free(mnt_cache, mnt);
-}
-
-/*
- * Now, lookup_mnt increments the ref count before returning
- * the vfsmount struct.
- */
-struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
-{
- struct list_head * head = mount_hashtable + hash(mnt, dentry);
- struct list_head * tmp = head;
- struct vfsmount *p, *found = NULL;
-
- spin_lock(&vfsmount_lock);
- for (;;) {
- tmp = tmp->next;
- p = NULL;
- if (tmp == head)
- break;
- p = list_entry(tmp, struct vfsmount, mnt_hash);
- if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) {
- found = mntget(p);
- break;
- }
- }
- spin_unlock(&vfsmount_lock);
- return found;
-}
-
-static inline int check_mnt(struct vfsmount *mnt)
-{
- return mnt->mnt_namespace == current->namespace;
-}
-
-static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd)
-{
- old_nd->dentry = mnt->mnt_mountpoint;
- old_nd->mnt = mnt->mnt_parent;
- mnt->mnt_parent = mnt;
- mnt->mnt_mountpoint = mnt->mnt_root;
- list_del_init(&mnt->mnt_child);
- list_del_init(&mnt->mnt_hash);
- old_nd->dentry->d_mounted--;
-}
-
-static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd)
-{
- mnt->mnt_parent = mntget(nd->mnt);
- mnt->mnt_mountpoint = dget(nd->dentry);
- list_add(&mnt->mnt_hash, mount_hashtable+hash(nd->mnt, nd->dentry));
- list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts);
- nd->dentry->d_mounted++;
-}
-
-static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root)
-{
- struct list_head *next = p->mnt_mounts.next;
- if (next == &p->mnt_mounts) {
- while (1) {
- if (p == root)
- return NULL;
- next = p->mnt_child.next;
- if (next != &p->mnt_parent->mnt_mounts)
- break;
- p = p->mnt_parent;
- }
- }
- return list_entry(next, struct vfsmount, mnt_child);
-}
-
-static struct vfsmount *
-clone_mnt(struct vfsmount *old, struct dentry *root)
-{
- struct super_block *sb = old->mnt_sb;
- struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
-
- if (mnt) {
- mnt->mnt_flags = old->mnt_flags;
- atomic_inc(&sb->s_active);
- mnt->mnt_sb = sb;
- mnt->mnt_root = dget(root);
- mnt->mnt_mountpoint = mnt->mnt_root;
- mnt->mnt_parent = mnt;
- mnt->mnt_namespace = old->mnt_namespace;
- mnt->mnt_xid = old->mnt_xid;
-
- /* stick the duplicate mount on the same expiry list
- * as the original if that was on one */
- spin_lock(&vfsmount_lock);
- if (!list_empty(&old->mnt_fslink))
- list_add(&mnt->mnt_fslink, &old->mnt_fslink);
- spin_unlock(&vfsmount_lock);
- }
- return mnt;
-}
-
-void __mntput(struct vfsmount *mnt)
-{
- struct super_block *sb = mnt->mnt_sb;
- dput(mnt->mnt_root);
- free_vfsmnt(mnt);
- deactivate_super(sb);
-}
-
-EXPORT_SYMBOL(__mntput);
-
-/* iterator */
-static void *m_start(struct seq_file *m, loff_t *pos)
-{
- struct namespace *n = m->private;
- struct list_head *p;
- loff_t l = *pos;
-
- down_read(&n->sem);
- list_for_each(p, &n->list)
- if (!l--)
- return list_entry(p, struct vfsmount, mnt_list);
- return NULL;
-}
-
-static void *m_next(struct seq_file *m, void *v, loff_t *pos)
-{
- struct namespace *n = m->private;
- struct list_head *p = ((struct vfsmount *)v)->mnt_list.next;
- (*pos)++;
- return p==&n->list ? NULL : list_entry(p, struct vfsmount, mnt_list);
-}
-
-static void m_stop(struct seq_file *m, void *v)
-{
- struct namespace *n = m->private;
- up_read(&n->sem);
-}
-
-static inline void mangle(struct seq_file *m, const char *s)
-{
- seq_escape(m, s, " \t\n\\");
-}
-
-static int mnt_is_reachable(struct vfsmount *mnt)
-{
- struct vfsmount *root_mnt;
- struct dentry *root, *point;
- int ret;
-
- if (!mnt)
- return 1;
- if (mnt == mnt->mnt_namespace->root)
- return 1;
-
- spin_lock(&dcache_lock);
- root_mnt = current->fs->rootmnt;
- root = current->fs->root;
- point = root;
-
- while ((mnt != mnt->mnt_parent) && (mnt != root_mnt)) {
- point = mnt->mnt_mountpoint;
- mnt = mnt->mnt_parent;
- }
-
- ret = (mnt == root_mnt) && is_subdir(point, root);
-
- spin_unlock(&dcache_lock);
-
- return ret;
-}
-
-static int show_vfsmnt(struct seq_file *m, void *v)
-{
- struct vfsmount *mnt = v;
- int err = 0;
- static struct proc_fs_info {
- int flag;
- char *str;
- } fs_info[] = {
- { MS_SYNCHRONOUS, ",sync" },
- { MS_DIRSYNC, ",dirsync" },
- { MS_MANDLOCK, ",mand" },
- { MS_NOATIME, ",noatime" },
- { MS_NODIRATIME, ",nodiratime" },
- { MS_TAGXID, ",tagxid" },
- { 0, NULL }
- };
- static struct proc_fs_info mnt_info[] = {
- { MNT_NOSUID, ",nosuid" },
- { MNT_NODEV, ",nodev" },
- { MNT_NOEXEC, ",noexec" },
- { 0, NULL }
- };
- struct proc_fs_info *fs_infop;
-
- if (vx_flags(VXF_HIDE_MOUNT, 0))
- return 0;
- if (!mnt_is_reachable(mnt))
- return 0;
-
- if (!vx_check(0, VX_ADMIN|VX_WATCH) &&
- mnt == current->fs->rootmnt) {
- seq_puts(m, "/dev/root / ");
- } else {
- mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
- seq_putc(m, ' ');
- seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
- seq_putc(m, ' ');
- }
- mangle(m, mnt->mnt_sb->s_type->name);
- seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw");
- for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
- if (mnt->mnt_sb->s_flags & fs_infop->flag)
- seq_puts(m, fs_infop->str);
- }
- for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
- if (mnt->mnt_flags & fs_infop->flag)
- seq_puts(m, fs_infop->str);
- }
- if (mnt->mnt_flags & MNT_XID)
- seq_printf(m, ",xid=%d", mnt->mnt_xid);
- if (mnt->mnt_sb->s_op->show_options)
- err = mnt->mnt_sb->s_op->show_options(m, mnt);
- seq_puts(m, " 0 0\n");
- return err;
-}
-
-struct seq_operations mounts_op = {
- .start = m_start,
- .next = m_next,
- .stop = m_stop,
- .show = show_vfsmnt
-};
-
-/**
- * may_umount_tree - check if a mount tree is busy
- * @mnt: root of mount tree
- *
- * This is called to check if a tree of mounts has any
- * open files, pwds, chroots or sub mounts that are
- * busy.
- */
-int may_umount_tree(struct vfsmount *mnt)
-{
- struct list_head *next;
- struct vfsmount *this_parent = mnt;
- int actual_refs;
- int minimum_refs;
-
- spin_lock(&vfsmount_lock);
- actual_refs = atomic_read(&mnt->mnt_count);
- minimum_refs = 2;
-repeat:
- next = this_parent->mnt_mounts.next;
-resume:
- while (next != &this_parent->mnt_mounts) {
- struct vfsmount *p = list_entry(next, struct vfsmount, mnt_child);
-
- next = next->next;
-
- actual_refs += atomic_read(&p->mnt_count);
- minimum_refs += 2;
-
- if (!list_empty(&p->mnt_mounts)) {
- this_parent = p;
- goto repeat;
- }
- }
-
- if (this_parent != mnt) {
- next = this_parent->mnt_child.next;
- this_parent = this_parent->mnt_parent;
- goto resume;
- }
- spin_unlock(&vfsmount_lock);
-
- if (actual_refs > minimum_refs)
- return -EBUSY;
-
- return 0;
-}
-
-EXPORT_SYMBOL(may_umount_tree);
-
-/**
- * may_umount - check if a mount point is busy
- * @mnt: root of mount
- *
- * This is called to check if a mount point has any
- * open files, pwds, chroots or sub mounts. If the
- * mount has sub mounts this will return busy
- * regardless of whether the sub mounts are busy.
- *
- * Doesn't take quota and stuff into account. IOW, in some cases it will
- * give false negatives. The main reason why it's here is that we need
- * a non-destructive way to look for easily umountable filesystems.
- */
-int may_umount(struct vfsmount *mnt)
-{
- if (atomic_read(&mnt->mnt_count) > 2)
- return -EBUSY;
- return 0;
-}
-
-EXPORT_SYMBOL(may_umount);
-
-static inline void __umount_list(struct list_head *kill)
-{
- struct vfsmount *mnt;
-
- while (!list_empty(kill)) {
- mnt = list_entry(kill->next, struct vfsmount, mnt_list);
- list_del_init(&mnt->mnt_list);
- list_del_init(&mnt->mnt_fslink);
- if (mnt->mnt_parent == mnt) {
- spin_unlock(&vfsmount_lock);
- } else {
- struct nameidata old_nd;
- detach_mnt(mnt, &old_nd);
- spin_unlock(&vfsmount_lock);
- path_release(&old_nd);
- }
- mntput(mnt);
- spin_lock(&vfsmount_lock);
- }
-}
-
-void umount_tree(struct vfsmount *mnt)
-{
- struct vfsmount *p;
- LIST_HEAD(kill);
-
- for (p = mnt; p; p = next_mnt(p, mnt)) {
- list_del(&p->mnt_list);
- list_add(&p->mnt_list, &kill);
- }
- __umount_list(&kill);
-}
-
-void umount_unused(struct vfsmount *mnt, struct fs_struct *fs)
-{
- struct vfsmount *p;
- LIST_HEAD(kill);
-
- for (p = mnt; p; p = next_mnt(p, mnt)) {
- if (p == fs->rootmnt || p == fs->pwdmnt)
- continue;
- list_del(&p->mnt_list);
- list_add(&p->mnt_list, &kill);
- }
- __umount_list(&kill);
-}
-
-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) && !vx_ccaps(VXC_SECURE_MOUNT))
- 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;
- if (vx_ccaps(VXC_SECURE_MOUNT))
- 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, xid_t xid, int flags)
-{
- struct nameidata old_nd;
- struct vfsmount *mnt = NULL;
- int err = mount_is_safe(nd);
- int recurse = flags & MS_REC;
- 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);
-
- if (flags & MS_XID) {
- mnt->mnt_xid = xid;
- mnt->mnt_flags |= MNT_XID;
- }
- 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, xid_t xid)
-{
- int err;
- struct super_block * sb = nd->mnt->mnt_sb;
-
- if (!capable(CAP_SYS_ADMIN) && !vx_ccaps(VXC_SECURE_REMOUNT))
- return -EPERM;
-
- if (!check_mnt(nd->mnt))
- return -EINVAL;
-
- if (nd->dentry != nd->mnt->mnt_root)
- return -EINVAL;
-
- if (vx_ccaps(VXC_SECURE_REMOUNT))
- mnt_flags |= MNT_NODEV;
- down_write(&sb->s_umount);
- err = do_remount_sb(sb, flags, data, 0);
- if (!err) {
- nd->mnt->mnt_flags=mnt_flags;
- if (flags & MS_XID)
- nd->mnt->mnt_xid = xid;
- }
- 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) && !vx_ccaps(VXC_SECURE_MOUNT))
- 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) && !vx_ccaps(VXC_SECURE_MOUNT))
- 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;
- xid_t xid = 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;
-
- retval = vx_parse_xid(data_page, &xid, 1);
- if (retval) {
- mnt_flags |= MNT_XID;
- /* bind and re-mounts get xid flag */
- if (flags & (MS_BIND|MS_REMOUNT))
- flags |= MS_XID;
- }
-
- /* 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);
-
- if (vx_ccaps(VXC_SECURE_MOUNT))
- mnt_flags |= MNT_NODEV;
-
- /* ... 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, xid);
- else if (flags & MS_BIND)
- retval = do_loopback(&nd, dev_name, xid, 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;
-}
-
-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) && !vx_ccaps(VXC_SECURE_MOUNT)) {
- 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);
-}
-
-/*
- * Moves the current root to put_root, and sets root/cwd of all processes
- * which had them on the old root to new_root.
- *
- * Note:
- * - 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 */
- error = -EINVAL;
- if (user_nd.mnt->mnt_root != user_nd.dentry)
- goto out2;
- 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;
- 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);
- attach_mnt(new_nd.mnt, &root_parent);
- 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 long order;
- unsigned int nr_hash;
- int i;
-
- mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
- 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
-
- order = 0;
- mount_hashtable = (struct list_head *)
- __get_free_pages(GFP_ATOMIC, order);
-
- 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 = (1UL << order) * 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 (order: %ld, %ld bytes)\n",
- nr_hash, order, (PAGE_SIZE << order));
-
- /* 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);
-}
git://git.onelab.eu / linux-2.6.git / commitdiff