LXR linux/fs/autofs/autofs

   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        struct inode    *inode;
  55
  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
  84struct 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 dev;
  91        u64 ino;
  92        kuid_t uid;
  93        kgid_t gid;
  94        pid_t pid;
  95        pid_t tgid;
  96        /* This is for status reporting upon return */
  97        int status;
  98        unsigned int wait_ctr;
  99};
 100
 101#define AUTOFS_SBI_MAGIC 0x6d4a556d
 102
 103#define AUTOFS_SBI_CATATONIC    0x0001
 104#define AUTOFS_SBI_STRICTEXPIRE 0x0002
 105#define AUTOFS_SBI_IGNORE       0x0004
 106
 107struct autofs_sb_info {
 108        u32 magic;
 109        int pipefd;
 110        struct file *pipe;
 111        struct pid *oz_pgrp;
 112        int version;
 113        int sub_version;
 114        int min_proto;
 115        int max_proto;
 116        unsigned int flags;
 117        unsigned long exp_timeout;
 118        unsigned int type;
 119        struct super_block *sb;
 120        struct mutex wq_mutex;
 121        struct mutex pipe_mutex;
 122        spinlock_t fs_lock;
 123        struct autofs_wait_queue *queues; /* Wait queue pointer */
 124        spinlock_t lookup_lock;
 125        struct list_head active_list;
 126        struct list_head expiring_list;
 127        struct rcu_head rcu;
 128};
 129
 130static inline struct autofs_sb_info *autofs_sbi(struct super_block *sb)
 131{
 132        return (struct autofs_sb_info *)(sb->s_fs_info);
 133}
 134
 135static inline struct autofs_info *autofs_dentry_ino(struct dentry *dentry)
 136{
 137        return (struct autofs_info *)(dentry->d_fsdata);
 138}
 139
 140/* autofs_oz_mode(): do we see the man behind the curtain?  (The
 141 * processes which do manipulations for us in user space sees the raw
 142 * filesystem without "magic".)
 143 */
 144static inline int autofs_oz_mode(struct autofs_sb_info *sbi)
 145{
 146        return ((sbi->flags & AUTOFS_SBI_CATATONIC) ||
 147                 task_pgrp(current) == sbi->oz_pgrp);
 148}
 149
 150struct inode *autofs_get_inode(struct super_block *, umode_t);
 151void autofs_free_ino(struct autofs_info *);
 152
 153/* Expiration */
 154int is_autofs_dentry(struct dentry *);
 155int autofs_expire_wait(const struct path *path, int rcu_walk);
 156int autofs_expire_run(struct super_block *, struct vfsmount *,
 157                      struct autofs_sb_info *,
 158                      struct autofs_packet_expire __user *);
 159int autofs_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
 160                           struct autofs_sb_info *sbi, unsigned int how);
 161int autofs_expire_multi(struct super_block *, struct vfsmount *,
 162                        struct autofs_sb_info *, int __user *);
 163
 164/* Device node initialization */
 165
 166int autofs_dev_ioctl_init(void);
 167void autofs_dev_ioctl_exit(void);
 168
 169/* Operations structures */
 170
 171extern const struct inode_operations autofs_symlink_inode_operations;
 172extern const struct inode_operations autofs_dir_inode_operations;
 173extern const struct file_operations autofs_dir_operations;
 174extern const struct file_operations autofs_root_operations;
 175extern const struct dentry_operations autofs_dentry_operations;
 176
 177/* VFS automount flags management functions */
 178static inline void __managed_dentry_set_managed(struct dentry *dentry)
 179{
 180        dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
 181}
 182
 183static inline void managed_dentry_set_managed(struct dentry *dentry)
 184{
 185        spin_lock(&dentry->d_lock);
 186        __managed_dentry_set_managed(dentry);
 187        spin_unlock(&dentry->d_lock);
 188}
 189
 190static inline void __managed_dentry_clear_managed(struct dentry *dentry)
 191{
 192        dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
 193}
 194
 195static inline void managed_dentry_clear_managed(struct dentry *dentry)
 196{
 197        spin_lock(&dentry->d_lock);
 198        __managed_dentry_clear_managed(dentry);
 199        spin_unlock(&dentry->d_lock);
 200}
 201
 202/* Initializing function */
 203
 204int autofs_fill_super(struct super_block *, void *, int);
 205struct autofs_info *autofs_new_ino(struct autofs_sb_info *);
 206void autofs_clean_ino(struct autofs_info *);
 207
 208static inline int autofs_prepare_pipe(struct file *pipe)
 209{
 210        if (!(pipe->f_mode & FMODE_CAN_WRITE))
 211                return -EINVAL;
 212        if (!S_ISFIFO(file_inode(pipe)->i_mode))
 213                return -EINVAL;
 214        /* We want a packet pipe */
 215        pipe->f_flags |= O_DIRECT;
 216        /* We don't expect -EAGAIN */
 217        pipe->f_flags &= ~O_NONBLOCK;
 218        return 0;
 219}
 220
 221/* Queue management functions */
 222
 223int autofs_wait(struct autofs_sb_info *,
 224                 const struct path *, enum autofs_notify);
 225int autofs_wait_release(struct autofs_sb_info *, autofs_wqt_t, int);
 226void autofs_catatonic_mode(struct autofs_sb_info *);
 227
 228static inline u32 autofs_get_dev(struct autofs_sb_info *sbi)
 229{
 230        return new_encode_dev(sbi->sb->s_dev);
 231}
 232
 233static inline u64 autofs_get_ino(struct autofs_sb_info *sbi)
 234{
 235        return d_inode(sbi->sb->s_root)->i_ino;
 236}
 237
 238static inline void __autofs_add_expiring(struct dentry *dentry)
 239{
 240        struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
 241        struct autofs_info *ino = autofs_dentry_ino(dentry);
 242
 243        if (ino) {
 244                if (list_empty(&ino->expiring))
 245                        list_add(&ino->expiring, &sbi->expiring_list);
 246        }
 247}
 248
 249static inline void autofs_add_expiring(struct dentry *dentry)
 250{
 251        struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
 252        struct autofs_info *ino = autofs_dentry_ino(dentry);
 253
 254        if (ino) {
 255                spin_lock(&sbi->lookup_lock);
 256                if (list_empty(&ino->expiring))
 257                        list_add(&ino->expiring, &sbi->expiring_list);
 258                spin_unlock(&sbi->lookup_lock);
 259        }
 260}
 261
 262static inline void autofs_del_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                spin_lock(&sbi->lookup_lock);
 269                if (!list_empty(&ino->expiring))
 270                        list_del_init(&ino->expiring);
 271                spin_unlock(&sbi->lookup_lock);
 272        }
 273}
 274
 275void autofs_kill_sb(struct super_block *);
 276