// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright 2008 Red Hat, Inc. All rights reserved. * Copyright 2008 Ian Kent <[email protected]> */ #include <linux/module.h> #include <linux/miscdevice.h> #include <linux/compat.h> #include <linux/fdtable.h> #include <linux/magic.h> #include <linux/nospec.h> #include "autofs_i.h" /* * This module implements an interface for routing autofs ioctl control * commands via a miscellaneous device file. * * The alternate interface is needed because we need to be able open * an ioctl file descriptor on an autofs mount that may be covered by * another mount. This situation arises when starting automount(8) * or other user space daemon which uses direct mounts or offset * mounts (used for autofs lazy mount/umount of nested mount trees), * which have been left busy at service shutdown. */ ioctl_fn; static int check_name(const char *name) { … } /* * Check a string doesn't overrun the chunk of * memory we copied from user land. */ static int invalid_str(char *str, size_t size) { … } /* * Check that the user compiled against correct version of autofs * misc device code. * * As well as checking the version compatibility this always copies * the kernel interface version out. */ static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param) { … } /* * Copy parameter control struct, including a possible path allocated * at the end of the struct. */ static struct autofs_dev_ioctl * copy_dev_ioctl(struct autofs_dev_ioctl __user *in) { … } static inline void free_dev_ioctl(struct autofs_dev_ioctl *param) { … } /* * Check sanity of parameter control fields and if a path is present * check that it is terminated and contains at least one "/". */ static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param) { … } /* Return autofs dev ioctl version */ static int autofs_dev_ioctl_version(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* Return autofs module protocol version */ static int autofs_dev_ioctl_protover(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* Return autofs module protocol sub version */ static int autofs_dev_ioctl_protosubver(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* Find the topmost mount satisfying test() */ static int find_autofs_mount(const char *pathname, struct path *res, int test(const struct path *path, void *data), void *data) { … } static int test_by_dev(const struct path *path, void *p) { … } static int test_by_type(const struct path *path, void *p) { … } /* * Open a file descriptor on the autofs mount point corresponding * to the given path and device number (aka. new_encode_dev(sb->s_dev)). */ static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid) { … } /* Open a file descriptor on an autofs mount point */ static int autofs_dev_ioctl_openmount(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* Close file descriptor allocated above (user can also use close(2)). */ static int autofs_dev_ioctl_closemount(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* * Send "ready" status for an existing wait (either a mount or an expire * request). */ static int autofs_dev_ioctl_ready(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* * Send "fail" status for an existing wait (either a mount or an expire * request). */ static int autofs_dev_ioctl_fail(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* * Set the pipe fd for kernel communication to the daemon. * * Normally this is set at mount using an option but if we * are reconnecting to a busy mount then we need to use this * to tell the autofs mount about the new kernel pipe fd. In * order to protect mounts against incorrectly setting the * pipefd we also require that the autofs mount be catatonic. * * This also sets the process group id used to identify the * controlling process (eg. the owning automount(8) daemon). */ static int autofs_dev_ioctl_setpipefd(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* * Make the autofs mount point catatonic, no longer responsive to * mount requests. Also closes the kernel pipe file descriptor. */ static int autofs_dev_ioctl_catatonic(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* Set the autofs mount timeout */ static int autofs_dev_ioctl_timeout(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* * Return the uid and gid of the last request for the mount * * When reconstructing an autofs mount tree with active mounts * we need to re-connect to mounts that may have used the original * process uid and gid (or string variations of them) for mount * lookups within the map entry. */ static int autofs_dev_ioctl_requester(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* * Call repeatedly until it returns -EAGAIN, meaning there's nothing * more that can be done. */ static int autofs_dev_ioctl_expire(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* Check if autofs mount point is in use */ static int autofs_dev_ioctl_askumount(struct file *fp, struct autofs_sb_info *sbi, struct autofs_dev_ioctl *param) { … } /* * Check if the given path is a mountpoint. * * If we are supplied with the file descriptor of an autofs * mount we're looking for a specific mount. In this case * the path is considered a mountpoint if it is itself a * mountpoint or contains a mount, such as a multi-mount * without a root mount. In this case we return 1 if the * path is a mount point and the super magic of the covering * mount if there is one or 0 if it isn't a mountpoint. * * If we aren't supplied with a file descriptor then we * lookup the path and check if it is the root of a mount. * If a type is given we are looking for a particular autofs * mount and if we don't find a match we return fail. If the * located path is the root of a mount we return 1 along with * the super magic of the mount or 0 otherwise. * * In both cases 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) { … } /* * 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) … static ioctl_fn lookup_dev_ioctl(unsigned int cmd) { … } /* ioctl dispatcher */ static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user) { … } static long autofs_dev_ioctl(struct file *file, unsigned int command, unsigned long u) { … } #ifdef CONFIG_COMPAT static long autofs_dev_ioctl_compat(struct file *file, unsigned int command, unsigned long u) { … } #else #define autofs_dev_ioctl_compat … #endif static const struct file_operations _dev_ioctl_fops = …; static struct miscdevice _autofs_dev_ioctl_misc = …; MODULE_ALIAS_MISCDEV(…); MODULE_ALIAS(…) …; /* Register/deregister misc character device */ int __init autofs_dev_ioctl_init(void) { … } void autofs_dev_ioctl_exit(void) { … }
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