767 lines
18 KiB
C
767 lines
18 KiB
C
/*
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* Copyright 2008 Red Hat, Inc. All rights reserved.
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* Copyright 2008 Ian Kent <raven@themaw.net>
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*
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* This file is part of the Linux kernel and is made available under
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* the terms of the GNU General Public License, version 2, or at your
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* option, any later version, incorporated herein by reference.
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*/
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#include <linux/module.h>
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#include <linux/vmalloc.h>
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#include <linux/miscdevice.h>
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#include <linux/init.h>
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#include <linux/wait.h>
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#include <linux/namei.h>
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#include <linux/fcntl.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/sched.h>
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#include <linux/compat.h>
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#include <linux/syscalls.h>
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#include <linux/magic.h>
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#include <linux/dcache.h>
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#include <linux/uaccess.h>
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#include <linux/slab.h>
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#include "autofs_i.h"
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/*
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* This module implements an interface for routing autofs ioctl control
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* commands via a miscellaneous device file.
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*
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* The alternate interface is needed because we need to be able open
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* an ioctl file descriptor on an autofs mount that may be covered by
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* another mount. This situation arises when starting automount(8)
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* or other user space daemon which uses direct mounts or offset
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* mounts (used for autofs lazy mount/umount of nested mount trees),
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* which have been left busy at at service shutdown.
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*/
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#define AUTOFS_DEV_IOCTL_SIZE sizeof(struct autofs_dev_ioctl)
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typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
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struct autofs_dev_ioctl *);
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static int check_name(const char *name)
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{
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if (!strchr(name, '/'))
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return -EINVAL;
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return 0;
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}
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/*
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* Check a string doesn't overrun the chunk of
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* memory we copied from user land.
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*/
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static int invalid_str(char *str, size_t size)
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{
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if (memchr(str, 0, size))
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return 0;
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return -EINVAL;
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}
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/*
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* Check that the user compiled against correct version of autofs
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* misc device code.
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*
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* As well as checking the version compatibility this always copies
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* the kernel interface version out.
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*/
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static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
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{
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int err = 0;
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if ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
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(AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
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AUTOFS_WARN("ioctl control interface version mismatch: "
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"kernel(%u.%u), user(%u.%u), cmd(%d)",
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AUTOFS_DEV_IOCTL_VERSION_MAJOR,
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AUTOFS_DEV_IOCTL_VERSION_MINOR,
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param->ver_major, param->ver_minor, cmd);
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err = -EINVAL;
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}
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/* Fill in the kernel version. */
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param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
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param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
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return err;
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}
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/*
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* Copy parameter control struct, including a possible path allocated
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* at the end of the struct.
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*/
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static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
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{
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struct autofs_dev_ioctl tmp, *ads;
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if (copy_from_user(&tmp, in, sizeof(tmp)))
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return ERR_PTR(-EFAULT);
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if (tmp.size < sizeof(tmp))
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return ERR_PTR(-EINVAL);
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ads = kmalloc(tmp.size, GFP_KERNEL);
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if (!ads)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(ads, in, tmp.size)) {
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kfree(ads);
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return ERR_PTR(-EFAULT);
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}
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return ads;
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}
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static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
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{
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kfree(param);
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return;
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}
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/*
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* Check sanity of parameter control fields and if a path is present
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* check that it is terminated and contains at least one "/".
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*/
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static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
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{
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int err;
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err = check_dev_ioctl_version(cmd, param);
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if (err) {
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AUTOFS_WARN("invalid device control module version "
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"supplied for cmd(0x%08x)", cmd);
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goto out;
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}
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if (param->size > sizeof(*param)) {
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err = invalid_str(param->path, param->size - sizeof(*param));
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if (err) {
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AUTOFS_WARN(
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"path string terminator missing for cmd(0x%08x)",
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cmd);
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goto out;
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}
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err = check_name(param->path);
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if (err) {
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AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
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cmd);
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goto out;
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}
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}
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err = 0;
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out:
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return err;
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}
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/*
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* Get the autofs super block info struct from the file opened on
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* the autofs mount point.
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*/
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static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
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{
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struct autofs_sb_info *sbi = NULL;
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struct inode *inode;
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if (f) {
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inode = f->f_path.dentry->d_inode;
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sbi = autofs4_sbi(inode->i_sb);
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}
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return sbi;
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}
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/* Return autofs module protocol version */
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static int autofs_dev_ioctl_protover(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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param->protover.version = sbi->version;
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return 0;
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}
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/* Return autofs module protocol sub version */
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static int autofs_dev_ioctl_protosubver(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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param->protosubver.sub_version = sbi->sub_version;
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return 0;
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}
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static int find_autofs_mount(const char *pathname,
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struct path *res,
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int test(struct path *path, void *data),
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void *data)
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{
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struct path path;
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int err = kern_path(pathname, 0, &path);
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if (err)
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return err;
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err = -ENOENT;
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while (path.dentry == path.mnt->mnt_root) {
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if (path.mnt->mnt_sb->s_magic == AUTOFS_SUPER_MAGIC) {
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if (test(&path, data)) {
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path_get(&path);
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if (!err) /* already found some */
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path_put(res);
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*res = path;
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err = 0;
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}
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}
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if (!follow_up(&path))
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break;
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}
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path_put(&path);
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return err;
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}
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static int test_by_dev(struct path *path, void *p)
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{
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return path->mnt->mnt_sb->s_dev == *(dev_t *)p;
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}
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static int test_by_type(struct path *path, void *p)
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{
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struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
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return ino && ino->sbi->type & *(unsigned *)p;
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}
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static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
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{
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struct files_struct *files = current->files;
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struct fdtable *fdt;
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spin_lock(&files->file_lock);
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fdt = files_fdtable(files);
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BUG_ON(fdt->fd[fd] != NULL);
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rcu_assign_pointer(fdt->fd[fd], file);
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FD_SET(fd, fdt->close_on_exec);
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spin_unlock(&files->file_lock);
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}
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/*
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* Open a file descriptor on the autofs mount point corresponding
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* to the given path and device number (aka. new_encode_dev(sb->s_dev)).
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*/
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static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
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{
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int err, fd;
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fd = get_unused_fd();
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if (likely(fd >= 0)) {
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struct file *filp;
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struct path path;
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err = find_autofs_mount(name, &path, test_by_dev, &devid);
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if (err)
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goto out;
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/*
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* Find autofs super block that has the device number
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* corresponding to the autofs fs we want to open.
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*/
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filp = dentry_open(path.dentry, path.mnt, O_RDONLY,
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current_cred());
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if (IS_ERR(filp)) {
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err = PTR_ERR(filp);
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goto out;
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}
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autofs_dev_ioctl_fd_install(fd, filp);
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}
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return fd;
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out:
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put_unused_fd(fd);
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return err;
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}
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/* Open a file descriptor on an autofs mount point */
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static int autofs_dev_ioctl_openmount(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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const char *path;
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dev_t devid;
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int err, fd;
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/* param->path has already been checked */
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if (!param->openmount.devid)
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return -EINVAL;
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param->ioctlfd = -1;
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path = param->path;
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devid = new_decode_dev(param->openmount.devid);
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err = 0;
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fd = autofs_dev_ioctl_open_mountpoint(path, devid);
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if (unlikely(fd < 0)) {
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err = fd;
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goto out;
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}
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param->ioctlfd = fd;
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out:
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return err;
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}
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/* Close file descriptor allocated above (user can also use close(2)). */
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static int autofs_dev_ioctl_closemount(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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return sys_close(param->ioctlfd);
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}
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/*
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* Send "ready" status for an existing wait (either a mount or an expire
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* request).
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*/
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static int autofs_dev_ioctl_ready(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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autofs_wqt_t token;
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token = (autofs_wqt_t) param->ready.token;
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return autofs4_wait_release(sbi, token, 0);
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}
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/*
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* Send "fail" status for an existing wait (either a mount or an expire
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* request).
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*/
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static int autofs_dev_ioctl_fail(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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autofs_wqt_t token;
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int status;
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token = (autofs_wqt_t) param->fail.token;
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status = param->fail.status ? param->fail.status : -ENOENT;
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return autofs4_wait_release(sbi, token, status);
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}
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/*
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* Set the pipe fd for kernel communication to the daemon.
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*
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* Normally this is set at mount using an option but if we
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* are reconnecting to a busy mount then we need to use this
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* to tell the autofs mount about the new kernel pipe fd. In
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* order to protect mounts against incorrectly setting the
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* pipefd we also require that the autofs mount be catatonic.
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*
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* This also sets the process group id used to identify the
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* controlling process (eg. the owning automount(8) daemon).
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*/
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static int autofs_dev_ioctl_setpipefd(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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int pipefd;
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int err = 0;
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if (param->setpipefd.pipefd == -1)
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return -EINVAL;
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pipefd = param->setpipefd.pipefd;
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mutex_lock(&sbi->wq_mutex);
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if (!sbi->catatonic) {
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mutex_unlock(&sbi->wq_mutex);
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return -EBUSY;
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} else {
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struct file *pipe = fget(pipefd);
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if (!pipe->f_op || !pipe->f_op->write) {
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err = -EPIPE;
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fput(pipe);
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goto out;
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}
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sbi->oz_pgrp = task_pgrp_nr(current);
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sbi->pipefd = pipefd;
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sbi->pipe = pipe;
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sbi->catatonic = 0;
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}
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out:
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mutex_unlock(&sbi->wq_mutex);
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return err;
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}
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/*
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* Make the autofs mount point catatonic, no longer responsive to
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* mount requests. Also closes the kernel pipe file descriptor.
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*/
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static int autofs_dev_ioctl_catatonic(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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autofs4_catatonic_mode(sbi);
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return 0;
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}
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/* Set the autofs mount timeout */
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static int autofs_dev_ioctl_timeout(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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unsigned long timeout;
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timeout = param->timeout.timeout;
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param->timeout.timeout = sbi->exp_timeout / HZ;
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sbi->exp_timeout = timeout * HZ;
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return 0;
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}
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/*
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* Return the uid and gid of the last request for the mount
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*
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* When reconstructing an autofs mount tree with active mounts
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* we need to re-connect to mounts that may have used the original
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* process uid and gid (or string variations of them) for mount
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* lookups within the map entry.
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*/
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static int autofs_dev_ioctl_requester(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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struct autofs_info *ino;
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struct path path;
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dev_t devid;
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int err = -ENOENT;
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if (param->size <= sizeof(*param)) {
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err = -EINVAL;
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goto out;
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}
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devid = sbi->sb->s_dev;
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param->requester.uid = param->requester.gid = -1;
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err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
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if (err)
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goto out;
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ino = autofs4_dentry_ino(path.dentry);
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if (ino) {
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err = 0;
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autofs4_expire_wait(path.dentry);
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spin_lock(&sbi->fs_lock);
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param->requester.uid = ino->uid;
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param->requester.gid = ino->gid;
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spin_unlock(&sbi->fs_lock);
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}
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path_put(&path);
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out:
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return err;
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}
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/*
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* Call repeatedly until it returns -EAGAIN, meaning there's nothing
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* more that can be done.
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*/
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static int autofs_dev_ioctl_expire(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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struct vfsmount *mnt;
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int how;
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how = param->expire.how;
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mnt = fp->f_path.mnt;
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return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
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}
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/* Check if autofs mount point is in use */
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static int autofs_dev_ioctl_askumount(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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param->askumount.may_umount = 0;
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if (may_umount(fp->f_path.mnt))
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param->askumount.may_umount = 1;
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return 0;
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}
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/*
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* Check if the given path is a mountpoint.
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*
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* If we are supplied with the file descriptor of an autofs
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* mount we're looking for a specific mount. In this case
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* the path is considered a mountpoint if it is itself a
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* mountpoint or contains a mount, such as a multi-mount
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* without a root mount. In this case we return 1 if the
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* path is a mount point and the super magic of the covering
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* mount if there is one or 0 if it isn't a mountpoint.
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*
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* If we aren't supplied with a file descriptor then we
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* lookup the nameidata of the path and check if it is the
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* root of a mount. If a type is given we are looking for
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* a particular autofs mount and if we don't find a match
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* we return fail. If the located nameidata path is the
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* root of a mount we return 1 along with the super magic
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* of the mount or 0 otherwise.
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*
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* In both cases the the device number (as returned by
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* new_encode_dev()) is also returned.
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*/
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static int autofs_dev_ioctl_ismountpoint(struct file *fp,
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struct autofs_sb_info *sbi,
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struct autofs_dev_ioctl *param)
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{
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struct path path;
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const char *name;
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unsigned int type;
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unsigned int devid, magic;
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int err = -ENOENT;
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if (param->size <= sizeof(*param)) {
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err = -EINVAL;
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goto out;
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}
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name = param->path;
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type = param->ismountpoint.in.type;
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param->ismountpoint.out.devid = devid = 0;
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param->ismountpoint.out.magic = magic = 0;
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if (!fp || param->ioctlfd == -1) {
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if (autofs_type_any(type))
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err = kern_path(name, LOOKUP_FOLLOW, &path);
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else
|
|
err = find_autofs_mount(name, &path, test_by_type, &type);
|
|
if (err)
|
|
goto out;
|
|
devid = new_encode_dev(path.mnt->mnt_sb->s_dev);
|
|
err = 0;
|
|
if (path.mnt->mnt_root == path.dentry) {
|
|
err = 1;
|
|
magic = path.mnt->mnt_sb->s_magic;
|
|
}
|
|
} else {
|
|
dev_t dev = sbi->sb->s_dev;
|
|
|
|
err = find_autofs_mount(name, &path, test_by_dev, &dev);
|
|
if (err)
|
|
goto out;
|
|
|
|
devid = new_encode_dev(dev);
|
|
|
|
err = have_submounts(path.dentry);
|
|
|
|
if (follow_down(&path))
|
|
magic = path.mnt->mnt_sb->s_magic;
|
|
}
|
|
|
|
param->ismountpoint.out.devid = devid;
|
|
param->ismountpoint.out.magic = magic;
|
|
path_put(&path);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Our range of ioctl numbers isn't 0 based so we need to shift
|
|
* the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
|
|
* lookup.
|
|
*/
|
|
#define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
|
|
|
|
static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
|
|
{
|
|
static struct {
|
|
int cmd;
|
|
ioctl_fn fn;
|
|
} _ioctls[] = {
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
|
|
autofs_dev_ioctl_protover},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
|
|
autofs_dev_ioctl_protosubver},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
|
|
autofs_dev_ioctl_openmount},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
|
|
autofs_dev_ioctl_closemount},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
|
|
autofs_dev_ioctl_ready},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
|
|
autofs_dev_ioctl_fail},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
|
|
autofs_dev_ioctl_setpipefd},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
|
|
autofs_dev_ioctl_catatonic},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
|
|
autofs_dev_ioctl_timeout},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
|
|
autofs_dev_ioctl_requester},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
|
|
autofs_dev_ioctl_expire},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
|
|
autofs_dev_ioctl_askumount},
|
|
{cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
|
|
autofs_dev_ioctl_ismountpoint}
|
|
};
|
|
unsigned int idx = cmd_idx(cmd);
|
|
|
|
return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
|
|
}
|
|
|
|
/* ioctl dispatcher */
|
|
static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
|
|
{
|
|
struct autofs_dev_ioctl *param;
|
|
struct file *fp;
|
|
struct autofs_sb_info *sbi;
|
|
unsigned int cmd_first, cmd;
|
|
ioctl_fn fn = NULL;
|
|
int err = 0;
|
|
|
|
/* only root can play with this */
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
|
|
cmd = _IOC_NR(command);
|
|
|
|
if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
|
|
cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
|
|
return -ENOTTY;
|
|
}
|
|
|
|
/* Copy the parameters into kernel space. */
|
|
param = copy_dev_ioctl(user);
|
|
if (IS_ERR(param))
|
|
return PTR_ERR(param);
|
|
|
|
err = validate_dev_ioctl(command, param);
|
|
if (err)
|
|
goto out;
|
|
|
|
/* The validate routine above always sets the version */
|
|
if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
|
|
goto done;
|
|
|
|
fn = lookup_dev_ioctl(cmd);
|
|
if (!fn) {
|
|
AUTOFS_WARN("unknown command 0x%08x", command);
|
|
return -ENOTTY;
|
|
}
|
|
|
|
fp = NULL;
|
|
sbi = NULL;
|
|
|
|
/*
|
|
* For obvious reasons the openmount can't have a file
|
|
* descriptor yet. We don't take a reference to the
|
|
* file during close to allow for immediate release.
|
|
*/
|
|
if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
|
|
cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
|
|
fp = fget(param->ioctlfd);
|
|
if (!fp) {
|
|
if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
|
|
goto cont;
|
|
err = -EBADF;
|
|
goto out;
|
|
}
|
|
|
|
if (!fp->f_op) {
|
|
err = -ENOTTY;
|
|
fput(fp);
|
|
goto out;
|
|
}
|
|
|
|
sbi = autofs_dev_ioctl_sbi(fp);
|
|
if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
|
|
err = -EINVAL;
|
|
fput(fp);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Admin needs to be able to set the mount catatonic in
|
|
* order to be able to perform the re-open.
|
|
*/
|
|
if (!autofs4_oz_mode(sbi) &&
|
|
cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
|
|
err = -EACCES;
|
|
fput(fp);
|
|
goto out;
|
|
}
|
|
}
|
|
cont:
|
|
err = fn(fp, sbi, param);
|
|
|
|
if (fp)
|
|
fput(fp);
|
|
done:
|
|
if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
|
|
err = -EFAULT;
|
|
out:
|
|
free_dev_ioctl(param);
|
|
return err;
|
|
}
|
|
|
|
static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
|
|
{
|
|
int err;
|
|
err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
|
|
return (long) err;
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
|
|
{
|
|
return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
|
|
}
|
|
#else
|
|
#define autofs_dev_ioctl_compat NULL
|
|
#endif
|
|
|
|
static const struct file_operations _dev_ioctl_fops = {
|
|
.unlocked_ioctl = autofs_dev_ioctl,
|
|
.compat_ioctl = autofs_dev_ioctl_compat,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
static struct miscdevice _autofs_dev_ioctl_misc = {
|
|
.minor = AUTOFS_MINOR,
|
|
.name = AUTOFS_DEVICE_NAME,
|
|
.fops = &_dev_ioctl_fops
|
|
};
|
|
|
|
MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
|
|
MODULE_ALIAS("devname:autofs");
|
|
|
|
/* Register/deregister misc character device */
|
|
int autofs_dev_ioctl_init(void)
|
|
{
|
|
int r;
|
|
|
|
r = misc_register(&_autofs_dev_ioctl_misc);
|
|
if (r) {
|
|
AUTOFS_ERROR("misc_register failed for control device");
|
|
return r;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void autofs_dev_ioctl_exit(void)
|
|
{
|
|
misc_deregister(&_autofs_dev_ioctl_misc);
|
|
return;
|
|
}
|
|
|