/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *  Copyright 1997-1998 Transmeta Corporation - All Rights Reserved
 *  Copyright 2005-2006 Ian Kent <raven@themaw.net>
 */

/* Internal header file for autofs */

#include <linux/auto_fs.h>
#include <linux/auto_dev-ioctl.h>

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/string.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
#include <uapi/linux/mount.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/uaccess.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/completion.h>
#include <linux/file.h>
#include <linux/magic.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include "../mount.h"
#include <linux/ns_common.h>


/* This is the range of ioctl() numbers we claim as ours */
#define AUTOFS_IOC_FIRST     AUTOFS_IOC_READY
#define AUTOFS_IOC_COUNT     32

#define AUTOFS_DEV_IOCTL_IOC_FIRST      (AUTOFS_DEV_IOCTL_VERSION)
#define AUTOFS_DEV_IOCTL_IOC_COUNT \
        (AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD - AUTOFS_DEV_IOCTL_VERSION_CMD)

#ifdef pr_fmt
#undef pr_fmt
#endif
#define pr_fmt(fmt) KBUILD_MODNAME ":pid:%d:%s: " fmt, current->pid, __func__

extern struct file_system_type autofs_fs_type;

/*
 * Unified info structure.  This is pointed to by both the dentry and
 * inode structures.  Each file in the filesystem has an instance of this
 * structure.  It holds a reference to the dentry, so dentries are never
 * flushed while the file exists.  All name lookups are dealt with at the
 * dentry level, although the filesystem can interfere in the validation
 * process.  Readdir is implemented by traversing the dentry lists.
 */
struct autofs_info {
        struct dentry   *dentry;
        int             flags;

        struct completion expire_complete;

        struct list_head active;

        struct list_head expiring;

        struct autofs_sb_info *sbi;
        unsigned long exp_timeout;
        unsigned long last_used;
        int count;

        kuid_t uid;
        kgid_t gid;
        struct rcu_head rcu;
};

#define AUTOFS_INF_EXPIRING     (1<<0) /* dentry in the process of expiring */
#define AUTOFS_INF_WANT_EXPIRE  (1<<1) /* the dentry is being considered
                                        * for expiry, so RCU_walk is
                                        * not permitted.  If it progresses to
                                        * actual expiry attempt, the flag is
                                        * not cleared when EXPIRING is set -
                                        * in that case it gets cleared only
                                        * when it comes to clearing EXPIRING.
                                        */
#define AUTOFS_INF_PENDING      (1<<2) /* dentry pending mount */

#define AUTOFS_INF_EXPIRE_SET   (1<<3) /* per-dentry expire timeout set for
                                          this mount point.
                                        */
struct autofs_wait_queue {
        wait_queue_head_t queue;
        struct autofs_wait_queue *next;
        autofs_wqt_t wait_queue_token;
        /* We use the following to see what we are waiting for */
        struct qstr name;
        u32 offset;
        u32 dev;
        u64 ino;
        kuid_t uid;
        kgid_t gid;
        pid_t pid;
        pid_t tgid;
        /* This is for status reporting upon return */
        int status;
        unsigned int wait_ctr;
};

#define AUTOFS_SBI_MAGIC 0x6d4a556d

#define AUTOFS_SBI_CATATONIC    0x0001
#define AUTOFS_SBI_STRICTEXPIRE 0x0002
#define AUTOFS_SBI_IGNORE       0x0004

struct autofs_sb_info {
        u32 magic;
        int pipefd;
        struct file *pipe;
        struct pid *oz_pgrp;
        u64 mnt_ns_id;
        int version;
        int sub_version;
        int min_proto;
        int max_proto;
        unsigned int flags;
        unsigned long exp_timeout;
        unsigned int type;
        struct super_block *sb;
        struct mutex wq_mutex;
        struct mutex pipe_mutex;
        spinlock_t fs_lock;
        struct autofs_wait_queue *queues; /* Wait queue pointer */
        spinlock_t lookup_lock;
        struct list_head active_list;
        struct list_head expiring_list;
        struct rcu_head rcu;
};

static inline struct autofs_sb_info *autofs_sbi(struct super_block *sb)
{
        return (struct autofs_sb_info *)(sb->s_fs_info);
}

static inline struct autofs_info *autofs_dentry_ino(struct dentry *dentry)
{
        return (struct autofs_info *)(dentry->d_fsdata);
}

/* autofs_oz_mode(): do we see the man behind the curtain?  (The
 * processes which do manipulations for us in user space sees the raw
 * filesystem without "magic".)
 */
static inline int autofs_oz_mode(struct autofs_sb_info *sbi)
{
        return ((sbi->flags & AUTOFS_SBI_CATATONIC) ||
                 task_pgrp(current) == sbi->oz_pgrp);
}

static inline bool autofs_empty(struct autofs_info *ino)
{
        return ino->count < 2;
}

struct inode *autofs_get_inode(struct super_block *, umode_t);
void autofs_free_ino(struct autofs_info *);

/* Expiration */
int is_autofs_dentry(struct dentry *);
int autofs_expire_wait(const struct path *path, int rcu_walk);
int autofs_expire_run(struct super_block *, struct vfsmount *,
                      struct autofs_sb_info *,
                      struct autofs_packet_expire __user *);
int autofs_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
                           struct autofs_sb_info *sbi, unsigned int how);
int autofs_expire_multi(struct super_block *, struct vfsmount *,
                        struct autofs_sb_info *, int __user *);

/* Device node initialization */

int autofs_dev_ioctl_init(void);
void autofs_dev_ioctl_exit(void);

/* Operations structures */

extern const struct inode_operations autofs_symlink_inode_operations;
extern const struct inode_operations autofs_dir_inode_operations;
extern const struct file_operations autofs_dir_operations;
extern const struct file_operations autofs_root_operations;
extern const struct dentry_operations autofs_dentry_operations;

/* VFS automount flags management functions */
static inline void __managed_dentry_set_managed(struct dentry *dentry)
{
        dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
}

static inline void managed_dentry_set_managed(struct dentry *dentry)
{
        spin_lock(&dentry->d_lock);
        __managed_dentry_set_managed(dentry);
        spin_unlock(&dentry->d_lock);
}

static inline void __managed_dentry_clear_managed(struct dentry *dentry)
{
        dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT);
}

static inline void managed_dentry_clear_managed(struct dentry *dentry)
{
        spin_lock(&dentry->d_lock);
        __managed_dentry_clear_managed(dentry);
        spin_unlock(&dentry->d_lock);
}

/* Initializing function */

extern const struct fs_parameter_spec autofs_param_specs[];
int autofs_init_fs_context(struct fs_context *fc);
struct autofs_info *autofs_new_ino(struct autofs_sb_info *);
void autofs_clean_ino(struct autofs_info *);

static inline int autofs_check_pipe(struct file *pipe)
{
        if (pipe->f_mode & FMODE_PATH)
                return -EINVAL;
        if (!(pipe->f_mode & FMODE_CAN_WRITE))
                return -EINVAL;
        if (!S_ISFIFO(file_inode(pipe)->i_mode))
                return -EINVAL;
        return 0;
}

static inline void autofs_set_packet_pipe_flags(struct file *pipe)
{
        /* We want a packet pipe */
        pipe->f_flags |= O_DIRECT;
        /* We don't expect -EAGAIN */
        pipe->f_flags &= ~O_NONBLOCK;
}

static inline int autofs_prepare_pipe(struct file *pipe)
{
        int ret = autofs_check_pipe(pipe);
        if (ret < 0)
                return ret;
        autofs_set_packet_pipe_flags(pipe);
        return 0;
}

/* Queue management functions */

int autofs_wait(struct autofs_sb_info *,
                 const struct path *, enum autofs_notify);
int autofs_wait_release(struct autofs_sb_info *, autofs_wqt_t, int);
void autofs_catatonic_mode(struct autofs_sb_info *);

static inline u32 autofs_get_dev(struct autofs_sb_info *sbi)
{
        return new_encode_dev(sbi->sb->s_dev);
}

static inline u64 autofs_get_ino(struct autofs_sb_info *sbi)
{
        return d_inode(sbi->sb->s_root)->i_ino;
}

static inline void __autofs_add_expiring(struct dentry *dentry)
{
        struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
        struct autofs_info *ino = autofs_dentry_ino(dentry);

        if (ino) {
                if (list_empty(&ino->expiring))
                        list_add(&ino->expiring, &sbi->expiring_list);
        }
}

static inline void autofs_add_expiring(struct dentry *dentry)
{
        struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
        struct autofs_info *ino = autofs_dentry_ino(dentry);

        if (ino) {
                spin_lock(&sbi->lookup_lock);
                if (list_empty(&ino->expiring))
                        list_add(&ino->expiring, &sbi->expiring_list);
                spin_unlock(&sbi->lookup_lock);
        }
}

static inline void autofs_del_expiring(struct dentry *dentry)
{
        struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
        struct autofs_info *ino = autofs_dentry_ino(dentry);

        if (ino) {
                spin_lock(&sbi->lookup_lock);
                if (!list_empty(&ino->expiring))
                        list_del_init(&ino->expiring);
                spin_unlock(&sbi->lookup_lock);
        }
}

void autofs_kill_sb(struct super_block *);