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