diff options
| -rw-r--r-- | fs/namespace.c | 63 |
1 files changed, 46 insertions, 17 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 9f5a084b239f..1487982dbc24 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -660,7 +660,10 @@ Enomem: /* * @source_mnt : mount tree to be attached - * @nd : place the mount tree @source_mnt is 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. @@ -685,6 +688,21 @@ Enomem: * (+) 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. + * --------------------------------------------- + * | MOVE MOUNT OPERATION | + * |******************************************** + * | source-->| shared | private | + * | dest | | | + * | | | | | + * | v | | | + * |******************************************** + * | shared | shared (+) | shared (+) | + * | | | | + * |non-shared| shared (+*) | private | + * ********************************************* + * (+) 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. * * if the source mount is a tree, the operations explained above is * applied to each mount in the tree. @@ -692,7 +710,7 @@ Enomem: * in allocations. */ static int attach_recursive_mnt(struct vfsmount *source_mnt, - struct nameidata *nd) + struct nameidata *nd, struct nameidata *parent_nd) { LIST_HEAD(tree_list); struct vfsmount *dest_mnt = nd->mnt; @@ -708,8 +726,14 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, } spin_lock(&vfsmount_lock); - mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); - commit_tree(source_mnt); + 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); @@ -740,7 +764,7 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) err = -ENOENT; if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) - err = attach_recursive_mnt(mnt, nd); + err = attach_recursive_mnt(mnt, nd, NULL); out_unlock: up(&nd->dentry->d_inode->i_sem); if (!err) @@ -869,35 +893,36 @@ static int do_move_mount(struct nameidata *nd, char *old_name) if (IS_DEADDIR(nd->dentry->d_inode)) goto out1; - spin_lock(&vfsmount_lock); if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) - goto out2; + goto out1; err = -EINVAL; if (old_nd.dentry != old_nd.mnt->mnt_root) - goto out2; + goto out1; if (old_nd.mnt == old_nd.mnt->mnt_parent) - goto out2; + goto out1; if (S_ISDIR(nd->dentry->d_inode->i_mode) != S_ISDIR(old_nd.dentry->d_inode->i_mode)) - goto out2; - + 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; err = -ELOOP; for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) if (p == old_nd.mnt) - goto out2; - err = 0; + goto out1; - detach_mnt(old_nd.mnt, &parent_nd); - attach_mnt(old_nd.mnt, nd); - touch_namespace(current->namespace); + 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); -out2: spin_unlock(&vfsmount_lock); out1: up(&nd->dentry->d_inode->i_sem); @@ -1467,6 +1492,10 @@ asmlinkage long sys_pivot_root(const char __user * new_root, down_write(&namespace_sem); down(&old_nd.dentry->d_inode->i_sem); 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; |