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