autofs_i.h

  1/* SPDX-License-Identifier: GPL-2.0-or-later */
  2/*
  3 *  Copyright 1997-1998 Transmeta Corporation - All Rights Reserved
  4 *  Copyright 2005-2006 Ian Kent <raven@themaw.net>
  5 */
  6
  7/* Internal header file for autofs */
  8
  9#include <linux/auto_fs.h>
 10#include <linux/auto_dev-ioctl.h>
 11
 12#include <linux/kernel.h>
 13#include <linux/slab.h>
 14#include <linux/time.h>
 15#include <linux/string.h>
 16#include <linux/wait.h>
 17#include <linux/sched.h>
 18#include <linux/sched/signal.h>
 19#include <uapi/linux/mount.h>
 20#include <linux/mount.h>
 21#include <linux/namei.h>
 22#include <linux/uaccess.h>
 23#include <linux/mutex.h>
 24#include <linux/spinlock.h>
 25#include <linux/list.h>
 26#include <linux/completion.h>
 27#include <linux/file.h>
 28#include <linux/magic.h>
 29#include <linux/fs_context.h>
 30#include <linux/fs_parser.h>
 31#include "../mount.h"
 32#include <linux/ns_common.h>
 33
 34
 35/* This is the range of ioctl() numbers we claim as ours */
 36#define AUTOFS_IOC_FIRST     AUTOFS_IOC_READY
 37#define AUTOFS_IOC_COUNT     32
 38
 39#define AUTOFS_DEV_IOCTL_IOC_FIRST	(AUTOFS_DEV_IOCTL_VERSION)
 40#define AUTOFS_DEV_IOCTL_IOC_COUNT \
 41	(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD - AUTOFS_DEV_IOCTL_VERSION_CMD)
 42
 43#ifdef pr_fmt
 44#undef pr_fmt
 45#endif
 46#define pr_fmt(fmt) KBUILD_MODNAME ":pid:%d:%s: " fmt, current->pid, __func__
 47
 48extern struct file_system_type autofs_fs_type;
 49
 50/*
 51 * Unified info structure.  This is pointed to by both the dentry and
 52 * inode structures.  Each file in the filesystem has an instance of this
 53 * structure.  It holds a reference to the dentry, so dentries are never
 54 * flushed while the file exists.  All name lookups are dealt with at the
 55 * dentry level, although the filesystem can interfere in the validation
 56 * process.  Readdir is implemented by traversing the dentry lists.
 57 */
 58struct autofs_info {
 59	struct dentry	*dentry;
 60	int		flags;
 61
 62	struct completion expire_complete;
 63
 64	struct list_head active;
 65
 66	struct list_head expiring;
 67
 68	struct autofs_sb_info *sbi;
 69	unsigned long exp_timeout;
 70	unsigned long last_used;
 71	int count;
 72
 73	kuid_t uid;
 74	kgid_t gid;
 75	struct rcu_head rcu;
 76};
 77
 78#define AUTOFS_INF_EXPIRING	(1<<0) /* dentry in the process of expiring */
 79#define AUTOFS_INF_WANT_EXPIRE	(1<<1) /* the dentry is being considered
 80					* for expiry, so RCU_walk is
 81					* not permitted.  If it progresses to
 82					* actual expiry attempt, the flag is
 83					* not cleared when EXPIRING is set -
 84					* in that case it gets cleared only
 85					* when it comes to clearing EXPIRING.
 86					*/
 87#define AUTOFS_INF_PENDING	(1<<2) /* dentry pending mount */
 88
 89#define AUTOFS_INF_EXPIRE_SET	(1<<3) /* per-dentry expire timeout set for
 90					  this mount point.
 91					*/
 92struct autofs_wait_queue {
 93	wait_queue_head_t queue;
 94	struct autofs_wait_queue *next;
 95	autofs_wqt_t wait_queue_token;
 96	/* We use the following to see what we are waiting for */
 97	struct qstr name;
 98	u32 offset;
 99	u32 dev;
100	u64 ino;
101	kuid_t uid;
102	kgid_t gid;
103	pid_t pid;
104	pid_t tgid;
105	/* This is for status reporting upon return */
106	int status;
107	unsigned int wait_ctr;
108};
109
110#define AUTOFS_SBI_MAGIC 0x6d4a556d
111
112#define AUTOFS_SBI_CATATONIC	0x0001
113#define AUTOFS_SBI_STRICTEXPIRE 0x0002
114#define AUTOFS_SBI_IGNORE	0x0004
115
116struct autofs_sb_info {
117	u32 magic;
118	int pipefd;
119	struct file *pipe;
120	struct pid *oz_pgrp;
121	u64 mnt_ns_id;
122	int version;
123	int sub_version;
124	int min_proto;
125	int max_proto;
126	unsigned int flags;
127	unsigned long exp_timeout;
128	unsigned int type;
129	struct super_block *sb;
130	struct mutex wq_mutex;
131	struct mutex pipe_mutex;
132	spinlock_t fs_lock;
133	struct autofs_wait_queue *queues; /* Wait queue pointer */
134	spinlock_t lookup_lock;
135	struct list_head active_list;
136	struct list_head expiring_list;
137	struct rcu_head rcu;
138};
139
140static inline struct autofs_sb_info *autofs_sbi(struct super_block *sb)
141{
142	return (struct autofs_sb_info *)(sb->s_fs_info);
143}
144
145static inline struct autofs_info *autofs_dentry_ino(struct dentry *dentry)
146{
147	return (struct autofs_info *)(dentry->d_fsdata);
148}
149
150/* autofs_oz_mode(): do we see the man behind the curtain?  (The
151 * processes which do manipulations for us in user space sees the raw
152 * filesystem without "magic".)
153 */
154static inline int autofs_oz_mode(struct autofs_sb_info *sbi)
155{
156	return ((sbi->flags & AUTOFS_SBI_CATATONIC) ||
157		 task_pgrp(current) == sbi->oz_pgrp);
158}
159
160static inline bool autofs_empty(struct autofs_info *ino)
161{
162	return ino->count < 2;
163}
164
165struct inode *autofs_get_inode(struct super_block *, umode_t);
166void autofs_free_ino(struct autofs_info *);
167
168/* Expiration */
169int is_autofs_dentry(struct dentry *);
170int autofs_expire_wait(const struct path *path, int rcu_walk);
171int autofs_expire_run(struct super_block *, struct vfsmount *,
172		      struct autofs_sb_info *,
173		      struct autofs_packet_expire __user *);
174int autofs_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
175			   struct autofs_sb_info *sbi, unsigned int how);
176int autofs_expire_multi(struct super_block *, struct vfsmount *,
177			struct autofs_sb_info *, int __user *);
178
179/* Device node initialization */
180
181int autofs_dev_ioctl_init(void);
182void autofs_dev_ioctl_exit(void);
183
184/* Operations structures */
185
186extern const struct inode_operations autofs_symlink_inode_operations;
187extern const struct inode_operations autofs_dir_inode_operations;
188extern const struct file_operations autofs_dir_operations;
189extern const struct file_operations autofs_root_operations;
190extern const struct dentry_operations autofs_dentry_operations;
191
192/* VFS automount flags management functions */
193static inline void __managed_dentry_set_managed(struct dentry *dentry)
194{
195	dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
196}
197
198static inline void managed_dentry_set_managed(struct dentry *dentry)
199{
200	spin_lock(&dentry->d_lock);
201	__managed_dentry_set_managed(dentry);
202	spin_unlock(&dentry->d_lock);
203}
204
205static inline void __managed_dentry_clear_managed(struct dentry *dentry)
206{
207	dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
208}
209
210static inline void managed_dentry_clear_managed(struct dentry *dentry)
211{
212	spin_lock(&dentry->d_lock);
213	__managed_dentry_clear_managed(dentry);
214	spin_unlock(&dentry->d_lock);
215}
216
217/* Initializing function */
218
219extern const struct fs_parameter_spec autofs_param_specs[];
220int autofs_init_fs_context(struct fs_context *fc);
221struct autofs_info *autofs_new_ino(struct autofs_sb_info *);
222void autofs_clean_ino(struct autofs_info *);
223
224static inline int autofs_check_pipe(struct file *pipe)
225{
226	if (pipe->f_mode & FMODE_PATH)
227		return -EINVAL;
228	if (!(pipe->f_mode & FMODE_CAN_WRITE))
229		return -EINVAL;
230	if (!S_ISFIFO(file_inode(pipe)->i_mode))
231		return -EINVAL;
232	return 0;
233}
234
235static inline void autofs_set_packet_pipe_flags(struct file *pipe)
236{
237	/* We want a packet pipe */
238	pipe->f_flags |= O_DIRECT;
239	/* We don't expect -EAGAIN */
240	pipe->f_flags &= ~O_NONBLOCK;
241}
242
243static inline int autofs_prepare_pipe(struct file *pipe)
244{
245	int ret = autofs_check_pipe(pipe);
246	if (ret < 0)
247		return ret;
248	autofs_set_packet_pipe_flags(pipe);
249	return 0;
250}
251
252/* Queue management functions */
253
254int autofs_wait(struct autofs_sb_info *,
255		 const struct path *, enum autofs_notify);
256int autofs_wait_release(struct autofs_sb_info *, autofs_wqt_t, int);
257void autofs_catatonic_mode(struct autofs_sb_info *);
258
259static inline u32 autofs_get_dev(struct autofs_sb_info *sbi)
260{
261	return new_encode_dev(sbi->sb->s_dev);
262}
263
264static inline u64 autofs_get_ino(struct autofs_sb_info *sbi)
265{
266	return d_inode(sbi->sb->s_root)->i_ino;
267}
268
269static inline void __autofs_add_expiring(struct dentry *dentry)
270{
271	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
272	struct autofs_info *ino = autofs_dentry_ino(dentry);
273
274	if (ino) {
275		if (list_empty(&ino->expiring))
276			list_add(&ino->expiring, &sbi->expiring_list);
277	}
278}
279
280static inline void autofs_add_expiring(struct dentry *dentry)
281{
282	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
283	struct autofs_info *ino = autofs_dentry_ino(dentry);
284
285	if (ino) {
286		spin_lock(&sbi->lookup_lock);
287		if (list_empty(&ino->expiring))
288			list_add(&ino->expiring, &sbi->expiring_list);
289		spin_unlock(&sbi->lookup_lock);
290	}
291}
292
293static inline void autofs_del_expiring(struct dentry *dentry)
294{
295	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
296	struct autofs_info *ino = autofs_dentry_ino(dentry);
297
298	if (ino) {
299		spin_lock(&sbi->lookup_lock);
300		if (!list_empty(&ino->expiring))
301			list_del_init(&ino->expiring);
302		spin_unlock(&sbi->lookup_lock);
303	}
304}
305
306void autofs_kill_sb(struct super_block *);