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
44 extern 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 */
54 struct 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 last_used;
66 int count;
67
68 kuid_t uid;
69 kgid_t gid;
70 struct rcu_head rcu;
71 };
72
73 #define AUTOFS_INF_EXPIRING (1<<0) /* dentry in the process of expiring */
74 #define AUTOFS_INF_WANT_EXPIRE (1<<1) /* the dentry is being considered
75 * for expiry, so RCU_walk is
76 * not permitted. If it progresses to
77 * actual expiry attempt, the flag is
78 * not cleared when EXPIRING is set -
79 * in that case it gets cleared only
80 * when it comes to clearing EXPIRING.
81 */
82 #define AUTOFS_INF_PENDING (1<<2) /* dentry pending mount */
83
84 struct autofs_wait_queue {
85 wait_queue_head_t queue;
86 struct autofs_wait_queue *next;
87 autofs_wqt_t wait_queue_token;
88 /* We use the following to see what we are waiting for */
89 struct qstr name;
90 u32 offset;
91 u32 dev;
92 u64 ino;
93 kuid_t uid;
94 kgid_t gid;
95 pid_t pid;
96 pid_t tgid;
97 /* This is for status reporting upon return */
98 int status;
99 unsigned int wait_ctr;
100 };
101
102 #define AUTOFS_SBI_MAGIC 0x6d4a556d
103
104 #define AUTOFS_SBI_CATATONIC 0x0001
105 #define AUTOFS_SBI_STRICTEXPIRE 0x0002
106 #define AUTOFS_SBI_IGNORE 0x0004
107
108 struct autofs_sb_info {
109 u32 magic;
110 int pipefd;
111 struct file *pipe;
112 struct pid *oz_pgrp;
113 int version;
114 int sub_version;
115 int min_proto;
116 int max_proto;
117 unsigned int flags;
118 unsigned long exp_timeout;
119 unsigned int type;
120 struct super_block *sb;
121 struct mutex wq_mutex;
122 struct mutex pipe_mutex;
123 spinlock_t fs_lock;
124 struct autofs_wait_queue *queues; /* Wait queue pointer */
125 spinlock_t lookup_lock;
126 struct list_head active_list;
127 struct list_head expiring_list;
128 struct rcu_head rcu;
129 };
130
131 static inline struct autofs_sb_info *autofs_sbi(struct super_block *sb)
132 {
133 return (struct autofs_sb_info *)(sb->s_fs_info);
134 }
135
136 static inline struct autofs_info *autofs_dentry_ino(struct dentry *dentry)
137 {
138 return (struct autofs_info *)(dentry->d_fsdata);
139 }
140
141 /* autofs_oz_mode(): do we see the man behind the curtain? (The
142 * processes which do manipulations for us in user space sees the raw
143 * filesystem without "magic".)
144 */
145 static inline int autofs_oz_mode(struct autofs_sb_info *sbi)
146 {
147 return ((sbi->flags & AUTOFS_SBI_CATATONIC) ||
148 task_pgrp(current) == sbi->oz_pgrp);
149 }
150
151 static inline bool autofs_empty(struct autofs_info *ino)
152 {
153 return ino->count < 2;
154 }
155
156 struct inode *autofs_get_inode(struct super_block *, umode_t);
157 void autofs_free_ino(struct autofs_info *);
158
159 /* Expiration */
160 int is_autofs_dentry(struct dentry *);
161 int autofs_expire_wait(const struct path *path, int rcu_walk);
162 int autofs_expire_run(struct super_block *, struct vfsmount *,
163 struct autofs_sb_info *,
164 struct autofs_packet_expire __user *);
165 int autofs_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
166 struct autofs_sb_info *sbi, unsigned int how);
167 int autofs_expire_multi(struct super_block *, struct vfsmount *,
168 struct autofs_sb_info *, int __user *);
169
170 /* Device node initialization */
171
172 int autofs_dev_ioctl_init(void);
173 void autofs_dev_ioctl_exit(void);
174
175 /* Operations structures */
176
177 extern const struct inode_operations autofs_symlink_inode_operations;
178 extern const struct inode_operations autofs_dir_inode_operations;
179 extern const struct file_operations autofs_dir_operations;
180 extern const struct file_operations autofs_root_operations;
181 extern const struct dentry_operations autofs_dentry_operations;
182
183 /* VFS automount flags management functions */
184 static inline void __managed_dentry_set_managed(struct dentry *dentry)
185 {
186 dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
187 }
188
189 static inline void managed_dentry_set_managed(struct dentry *dentry)
190 {
191 spin_lock(&dentry->d_lock);
192 __managed_dentry_set_managed(dentry);
193 spin_unlock(&dentry->d_lock);
194 }
195
196 static inline void __managed_dentry_clear_managed(struct dentry *dentry)
197 {
198 dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
199 }
200
201 static inline void managed_dentry_clear_managed(struct dentry *dentry)
202 {
203 spin_lock(&dentry->d_lock);
204 __managed_dentry_clear_managed(dentry);
205 spin_unlock(&dentry->d_lock);
206 }
207
208 /* Initializing function */
209
210 extern const struct fs_parameter_spec autofs_param_specs[];
211 int autofs_init_fs_context(struct fs_context *fc);
212 struct autofs_info *autofs_new_ino(struct autofs_sb_info *);
213 void autofs_clean_ino(struct autofs_info *);
214
215 static inline int autofs_check_pipe(struct file *pipe)
216 {
217 if (!(pipe->f_mode & FMODE_CAN_WRITE))
218 return -EINVAL;
219 if (!S_ISFIFO(file_inode(pipe)->i_mode))
220 return -EINVAL;
221 return 0;
222 }
223
224 static inline void autofs_set_packet_pipe_flags(struct file *pipe)
225 {
226 /* We want a packet pipe */
227 pipe->f_flags |= O_DIRECT;
228 /* We don't expect -EAGAIN */
229 pipe->f_flags &= ~O_NONBLOCK;
230 }
231
232 static inline int autofs_prepare_pipe(struct file *pipe)
233 {
234 int ret = autofs_check_pipe(pipe);
235 if (ret < 0)
236 return ret;
237 autofs_set_packet_pipe_flags(pipe);
238 return 0;
239 }
240
241 /* Queue management functions */
242
243 int autofs_wait(struct autofs_sb_info *,
244 const struct path *, enum autofs_notify);
245 int autofs_wait_release(struct autofs_sb_info *, autofs_wqt_t, int);
246 void autofs_catatonic_mode(struct autofs_sb_info *);
247
248 static inline u32 autofs_get_dev(struct autofs_sb_info *sbi)
249 {
250 return new_encode_dev(sbi->sb->s_dev);
251 }
252
253 static inline u64 autofs_get_ino(struct autofs_sb_info *sbi)
254 {
255 return d_inode(sbi->sb->s_root)->i_ino;
256 }
257
258 static inline void __autofs_add_expiring(struct dentry *dentry)
259 {
260 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
261 struct autofs_info *ino = autofs_dentry_ino(dentry);
262
263 if (ino) {
264 if (list_empty(&ino->expiring))
265 list_add(&ino->expiring, &sbi->expiring_list);
266 }
267 }
268
269 static 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 spin_lock(&sbi->lookup_lock);
276 if (list_empty(&ino->expiring))
277 list_add(&ino->expiring, &sbi->expiring_list);
278 spin_unlock(&sbi->lookup_lock);
279 }
280 }
281
282 static inline void autofs_del_expiring(struct dentry *dentry)
283 {
284 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
285 struct autofs_info *ino = autofs_dentry_ino(dentry);
286
287 if (ino) {
288 spin_lock(&sbi->lookup_lock);
289 if (!list_empty(&ino->expiring))
290 list_del_init(&ino->expiring);
291 spin_unlock(&sbi->lookup_lock);
292 }
293 }
294
295 void autofs_kill_sb(struct super_block *);
296
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