fs/autofs/autofs_i.h

   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 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                                         */
  88 struct 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
 112 struct 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
 135 static inline struct autofs_sb_info *autofs_sbi(struct super_block *sb)
 136 {
 137         return (struct autofs_sb_info *)(sb->s_fs_info);
 138 }
 139
 140 static 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  */
 149 static 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
 155 static inline bool autofs_empty(struct autofs_info *ino)
 156 {
 157         return ino->count < 2;
 158 }
 159
 160 struct inode *autofs_get_inode(struct super_block *, umode_t);
 161 void autofs_free_ino(struct autofs_info *);
 162
 163 /* Expiration */
 164 int is_autofs_dentry(struct dentry *);
 165 int autofs_expire_wait(const struct path *path, int rcu_walk);
 166 int autofs_expire_run(struct super_block *, struct vfsmount *,
 167                       struct autofs_sb_info *,
 168                       struct autofs_packet_expire __user *);
 169 int autofs_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
 170                            struct autofs_sb_info *sbi, unsigned int how);
 171 int autofs_expire_multi(struct super_block *, struct vfsmount *,
 172                         struct autofs_sb_info *, int __user *);
 173
 174 /* Device node initialization */
 175
 176 int autofs_dev_ioctl_init(void);
 177 void autofs_dev_ioctl_exit(void);
 178
 179 /* Operations structures */
 180
 181 extern const struct inode_operations autofs_symlink_inode_operations;
 182 extern const struct inode_operations autofs_dir_inode_operations;
 183 extern const struct file_operations autofs_dir_operations;
 184 extern const struct file_operations autofs_root_operations;
 185 extern const struct dentry_operations autofs_dentry_operations;
 186
 187 /* VFS automount flags management functions */
 188 static inline void __managed_dentry_set_managed(struct dentry *dentry)
 189 {
 190         dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
 191 }
 192
 193 static 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
 200 static inline void __managed_dentry_clear_managed(struct dentry *dentry)
 201 {
 202         dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
 203 }
 204
 205 static 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
 214 extern const struct fs_parameter_spec autofs_param_specs[];
 215 int autofs_init_fs_context(struct fs_context *fc);
 216 struct autofs_info *autofs_new_ino(struct autofs_sb_info *);
 217 void autofs_clean_ino(struct autofs_info *);
 218
 219 static 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
 228 static 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
 236 static 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
 247 int autofs_wait(struct autofs_sb_info *,
 248                  const struct path *, enum autofs_notify);
 249 int autofs_wait_release(struct autofs_sb_info *, autofs_wqt_t, int);
 250 void autofs_catatonic_mode(struct autofs_sb_info *);
 251
 252 static inline u32 autofs_get_dev(struct autofs_sb_info *sbi)
 253 {
 254         return new_encode_dev(sbi->sb->s_dev);
 255 }
 256
 257 static inline u64 autofs_get_ino(struct autofs_sb_info *sbi)
 258 {
 259         return d_inode(sbi->sb->s_root)->i_ino;
 260 }
 261
 262 static 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
 273 static 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
 286 static 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
 299 void autofs_kill_sb(struct super_block *);