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