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![Tomas Bortoli](/assets/img/avatar_default.png)
The autofs subsystem does not check that the "path" parameter is present for all cases where it is required when it is passed in via the "param" struct. In particular it isn't checked for the AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ioctl command. To solve it, modify validate_dev_ioctl(function to check that a path has been provided for ioctl commands that require it. Link: http://lkml.kernel.org/r/153060031527.26631.18306637892746301555.stgit@pluto.themaw.net Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com> Signed-off-by: Ian Kent <raven@themaw.net> Reported-by: syzbot+60c837b428dc84e83a93@syzkaller.appspotmail.com Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
752 lines
18 KiB
C
752 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/miscdevice.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 "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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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 ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
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(param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
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pr_warn("ioctl control interface version mismatch: "
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"kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
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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 *
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copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
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{
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struct autofs_dev_ioctl tmp, *res;
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if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
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return ERR_PTR(-EFAULT);
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if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
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return ERR_PTR(-EINVAL);
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if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
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return ERR_PTR(-ENAMETOOLONG);
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res = memdup_user(in, tmp.size);
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if (!IS_ERR(res))
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res->size = tmp.size;
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return res;
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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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}
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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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pr_warn("invalid device control module version "
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"supplied for cmd(0x%08x)\n", cmd);
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goto out;
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}
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if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
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err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
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if (err) {
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pr_warn(
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"path string terminator missing for cmd(0x%08x)\n",
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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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pr_warn("invalid path supplied for cmd(0x%08x)\n",
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cmd);
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goto out;
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}
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} else {
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unsigned int inr = _IOC_NR(cmd);
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if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
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inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
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inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
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err = -EINVAL;
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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 = file_inode(f);
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sbi = autofs_sbi(inode->i_sb);
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}
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return sbi;
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}
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/* Return autofs dev ioctl version */
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static int autofs_dev_ioctl_version(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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/* This should have already been set. */
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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 0;
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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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/* Find the topmost mount satisfying test() */
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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(const 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;
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err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
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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.dentry->d_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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*res = path;
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err = 0;
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break;
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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(const struct path *path, void *p)
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{
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return path->dentry->d_sb->s_dev == *(dev_t *)p;
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}
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static int test_by_type(const struct path *path, void *p)
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{
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struct autofs_info *ino = autofs_dentry_ino(path->dentry);
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return ino && ino->sbi->type & *(unsigned *)p;
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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_flags(O_CLOEXEC);
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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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filp = dentry_open(&path, O_RDONLY, current_cred());
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path_put(&path);
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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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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 been checked in validate_dev_ioctl() */
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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 ksys_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 autofs_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 < 0 ? param->fail.status : -ENOENT;
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return autofs_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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struct pid *new_pid = NULL;
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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;
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new_pid = get_task_pid(current, PIDTYPE_PGID);
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if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
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pr_warn("not allowed to change PID namespace\n");
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err = -EINVAL;
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goto out;
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}
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pipe = fget(pipefd);
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if (!pipe) {
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err = -EBADF;
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goto out;
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}
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if (autofs_prepare_pipe(pipe) < 0) {
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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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swap(sbi->oz_pgrp, new_pid);
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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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put_pid(new_pid);
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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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autofs_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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/* param->path has been checked in validate_dev_ioctl() */
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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 = autofs_dentry_ino(path.dentry);
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if (ino) {
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err = 0;
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autofs_expire_wait(&path, 0);
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spin_lock(&sbi->fs_lock);
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param->requester.uid =
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from_kuid_munged(current_user_ns(), ino->uid);
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param->requester.gid =
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from_kgid_munged(current_user_ns(), 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 autofs_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 path and check if it is the root of a mount.
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* If a type is given we are looking for a particular autofs
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* mount and if we don't find a match we return fail. If the
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* located path is the root of a mount we return 1 along with
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* the super magic of the mount or 0 otherwise.
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*
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* In both cases the the device number (as returned by
|
|
* new_encode_dev()) is also returned.
|
|
*/
|
|
static int autofs_dev_ioctl_ismountpoint(struct file *fp,
|
|
struct autofs_sb_info *sbi,
|
|
struct autofs_dev_ioctl *param)
|
|
{
|
|
struct path path;
|
|
const char *name;
|
|
unsigned int type;
|
|
unsigned int devid, magic;
|
|
int err = -ENOENT;
|
|
|
|
/* param->path has been checked in validate_dev_ioctl() */
|
|
|
|
name = param->path;
|
|
type = param->ismountpoint.in.type;
|
|
|
|
param->ismountpoint.out.devid = devid = 0;
|
|
param->ismountpoint.out.magic = magic = 0;
|
|
|
|
if (!fp || param->ioctlfd == -1) {
|
|
if (autofs_type_any(type))
|
|
err = kern_path_mountpoint(AT_FDCWD,
|
|
name, &path, LOOKUP_FOLLOW);
|
|
else
|
|
err = find_autofs_mount(name, &path,
|
|
test_by_type, &type);
|
|
if (err)
|
|
goto out;
|
|
devid = new_encode_dev(path.dentry->d_sb->s_dev);
|
|
err = 0;
|
|
if (path.mnt->mnt_root == path.dentry) {
|
|
err = 1;
|
|
magic = path.dentry->d_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 = path_has_submounts(&path);
|
|
|
|
if (follow_down_one(&path))
|
|
magic = path.dentry->d_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 ioctl_fn _ioctls[] = {
|
|
autofs_dev_ioctl_version,
|
|
autofs_dev_ioctl_protover,
|
|
autofs_dev_ioctl_protosubver,
|
|
autofs_dev_ioctl_openmount,
|
|
autofs_dev_ioctl_closemount,
|
|
autofs_dev_ioctl_ready,
|
|
autofs_dev_ioctl_fail,
|
|
autofs_dev_ioctl_setpipefd,
|
|
autofs_dev_ioctl_catatonic,
|
|
autofs_dev_ioctl_timeout,
|
|
autofs_dev_ioctl_requester,
|
|
autofs_dev_ioctl_expire,
|
|
autofs_dev_ioctl_askumount,
|
|
autofs_dev_ioctl_ismountpoint,
|
|
};
|
|
unsigned int idx = cmd_idx(cmd);
|
|
|
|
return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
|
|
}
|
|
|
|
/* 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;
|
|
|
|
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;
|
|
}
|
|
|
|
/* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
|
|
* and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
|
|
*/
|
|
if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
|
|
cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
|
|
!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
/* 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;
|
|
|
|
fn = lookup_dev_ioctl(cmd);
|
|
if (!fn) {
|
|
pr_warn("unknown command 0x%08x\n", command);
|
|
err = -ENOTTY;
|
|
goto out;
|
|
}
|
|
|
|
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,
|
|
* and the same for retrieving ioctl version.
|
|
*/
|
|
if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
|
|
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;
|
|
}
|
|
|
|
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 (!autofs_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);
|
|
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, unsigned int command,
|
|
unsigned long 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, unsigned int command,
|
|
unsigned long u)
|
|
{
|
|
return autofs_dev_ioctl(file, command, (unsigned long) 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,
|
|
.llseek = noop_llseek,
|
|
};
|
|
|
|
static struct miscdevice _autofs_dev_ioctl_misc = {
|
|
.minor = AUTOFS_MINOR,
|
|
.name = AUTOFS_DEVICE_NAME,
|
|
.fops = &_dev_ioctl_fops,
|
|
.mode = 0644,
|
|
};
|
|
|
|
MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
|
|
MODULE_ALIAS("devname:autofs");
|
|
|
|
/* Register/deregister misc character device */
|
|
int __init autofs_dev_ioctl_init(void)
|
|
{
|
|
int r;
|
|
|
|
r = misc_register(&_autofs_dev_ioctl_misc);
|
|
if (r) {
|
|
pr_err("misc_register failed for control device\n");
|
|
return r;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void autofs_dev_ioctl_exit(void)
|
|
{
|
|
misc_deregister(&_autofs_dev_ioctl_misc);
|
|
}
|