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 
42 extern 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  */
52 struct 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 
82 struct 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 
106 struct 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 
autofs_sbi(struct super_block * sb)129 static inline struct autofs_sb_info *autofs_sbi(struct super_block *sb)
130 {
131 	return (struct autofs_sb_info *)(sb->s_fs_info);
132 }
133 
autofs_dentry_ino(struct dentry * dentry)134 static 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  */
autofs_oz_mode(struct autofs_sb_info * sbi)143 static 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 
autofs_empty(struct autofs_info * ino)149 static inline bool autofs_empty(struct autofs_info *ino)
150 {
151 	return ino->count < 2;
152 }
153 
154 struct inode *autofs_get_inode(struct super_block *, umode_t);
155 void autofs_free_ino(struct autofs_info *);
156 
157 /* Expiration */
158 int is_autofs_dentry(struct dentry *);
159 int autofs_expire_wait(const struct path *path, int rcu_walk);
160 int autofs_expire_run(struct super_block *, struct vfsmount *,
161 		      struct autofs_sb_info *,
162 		      struct autofs_packet_expire __user *);
163 int autofs_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
164 			   struct autofs_sb_info *sbi, unsigned int how);
165 int autofs_expire_multi(struct super_block *, struct vfsmount *,
166 			struct autofs_sb_info *, int __user *);
167 
168 /* Device node initialization */
169 
170 int autofs_dev_ioctl_init(void);
171 void autofs_dev_ioctl_exit(void);
172 
173 /* Operations structures */
174 
175 extern const struct inode_operations autofs_symlink_inode_operations;
176 extern const struct inode_operations autofs_dir_inode_operations;
177 extern const struct file_operations autofs_dir_operations;
178 extern const struct file_operations autofs_root_operations;
179 extern const struct dentry_operations autofs_dentry_operations;
180 
181 /* VFS automount flags management functions */
__managed_dentry_set_managed(struct dentry * dentry)182 static inline void __managed_dentry_set_managed(struct dentry *dentry)
183 {
184 	dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
185 }
186 
managed_dentry_set_managed(struct dentry * dentry)187 static 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 
__managed_dentry_clear_managed(struct dentry * dentry)194 static inline void __managed_dentry_clear_managed(struct dentry *dentry)
195 {
196 	dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
197 }
198 
managed_dentry_clear_managed(struct dentry * dentry)199 static 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 
208 int autofs_fill_super(struct super_block *, void *, int);
209 struct autofs_info *autofs_new_ino(struct autofs_sb_info *);
210 void autofs_clean_ino(struct autofs_info *);
211 
autofs_prepare_pipe(struct file * pipe)212 static 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 
227 int autofs_wait(struct autofs_sb_info *,
228 		 const struct path *, enum autofs_notify);
229 int autofs_wait_release(struct autofs_sb_info *, autofs_wqt_t, int);
230 void autofs_catatonic_mode(struct autofs_sb_info *);
231 
autofs_get_dev(struct autofs_sb_info * sbi)232 static inline u32 autofs_get_dev(struct autofs_sb_info *sbi)
233 {
234 	return new_encode_dev(sbi->sb->s_dev);
235 }
236 
autofs_get_ino(struct autofs_sb_info * sbi)237 static inline u64 autofs_get_ino(struct autofs_sb_info *sbi)
238 {
239 	return d_inode(sbi->sb->s_root)->i_ino;
240 }
241 
__autofs_add_expiring(struct dentry * dentry)242 static 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 
autofs_add_expiring(struct dentry * dentry)253 static 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 
autofs_del_expiring(struct dentry * dentry)266 static 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 
279 void autofs_kill_sb(struct super_block *);
280