fs/devpts/inode.c - kernel/msm-4.19 - Gitiles

 /* -*- linux-c -*- --------------------------------------------------------- *
  *
  * linux/fs/devpts/inode.c
  *
  *  Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
  *
  * This file is part of the Linux kernel and is made available under
  * the terms of the GNU General Public License, version 2, or at your
  * option, any later version, incorporated herein by reference.
  *
  * ------------------------------------------------------------------------- */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/sched.h>
 #include <linux/namei.h>
 #include <linux/mount.h>
 #include <linux/tty.h>
 #include <linux/mutex.h>
 #include <linux/idr.h>
 #include <linux/devpts_fs.h>
 #include <linux/parser.h>
 #include <linux/fsnotify.h>
 #include <linux/seq_file.h>

 #define DEVPTS_SUPER_MAGIC 0x1cd1

 #define DEVPTS_DEFAULT_MODE 0600

 extern int pty_limit;			/* Config limit on Unix98 ptys */
 static DEFINE_IDA(allocated_ptys);
 static DEFINE_MUTEX(allocated_ptys_lock);

 static struct vfsmount *devpts_mnt;
 static struct dentry *devpts_root;

 static struct {
 	int setuid;
 	int setgid;
 	uid_t   uid;
 	gid_t   gid;
 	umode_t mode;
 } config = {.mode = DEVPTS_DEFAULT_MODE};

 enum {
 	Opt_uid, Opt_gid, Opt_mode,
 	Opt_err
 };

 static match_table_t tokens = {
 	{Opt_uid, "uid=%u"},
 	{Opt_gid, "gid=%u"},
 	{Opt_mode, "mode=%o"},
 	{Opt_err, NULL}
 };

 static int devpts_remount(struct super_block *sb, int *flags, char *data)
 {
 	char *p;

 	config.setuid  = 0;
 	config.setgid  = 0;
 	config.uid     = 0;
 	config.gid     = 0;
 	config.mode    = DEVPTS_DEFAULT_MODE;

 	while ((p = strsep(&data, ",")) != NULL) {
 		substring_t args[MAX_OPT_ARGS];
 		int token;
 		int option;

 		if (!*p)
 			continue;

 		token = match_token(p, tokens, args);
 		switch (token) {
 		case Opt_uid:
 			if (match_int(&args[0], &option))
 				return -EINVAL;
 			config.uid = option;
 			config.setuid = 1;
 			break;
 		case Opt_gid:
 			if (match_int(&args[0], &option))
 				return -EINVAL;
 			config.gid = option;
 			config.setgid = 1;
 			break;
 		case Opt_mode:
 			if (match_octal(&args[0], &option))
 				return -EINVAL;
 			config.mode = option & S_IALLUGO;
 			break;
 		default:
 			printk(KERN_ERR "devpts: called with bogus options\n");
 			return -EINVAL;
 		}
 	}

 	return 0;
 }

 static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs)
 {
 	if (config.setuid)
 		seq_printf(seq, ",uid=%u", config.uid);
 	if (config.setgid)
 		seq_printf(seq, ",gid=%u", config.gid);
 	seq_printf(seq, ",mode=%03o", config.mode);

 	return 0;
 }

 static const struct super_operations devpts_sops = {
 	.statfs		= simple_statfs,
 	.remount_fs	= devpts_remount,
 	.show_options	= devpts_show_options,
 };

 static int
 devpts_fill_super(struct super_block *s, void *data, int silent)
 {
 	struct inode * inode;

 	s->s_blocksize = 1024;
 	s->s_blocksize_bits = 10;
 	s->s_magic = DEVPTS_SUPER_MAGIC;
 	s->s_op = &devpts_sops;
 	s->s_time_gran = 1;

 	inode = new_inode(s);
 	if (!inode)
 		goto fail;
 	inode->i_ino = 1;
 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 	inode->i_blocks = 0;
 	inode->i_uid = inode->i_gid = 0;
 	inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
 	inode->i_op = &simple_dir_inode_operations;
 	inode->i_fop = &simple_dir_operations;
 	inode->i_nlink = 2;

 	devpts_root = s->s_root = d_alloc_root(inode);
 	if (s->s_root)
 		return 0;

 	printk("devpts: get root dentry failed\n");
 	iput(inode);
 fail:
 	return -ENOMEM;
 }

 static int devpts_get_sb(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
 	return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
 }

 static struct file_system_type devpts_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "devpts",
 	.get_sb		= devpts_get_sb,
 	.kill_sb	= kill_anon_super,
 };

 /*
  * The normal naming convention is simply /dev/pts/<number>; this conforms
  * to the System V naming convention
  */

 static struct dentry *get_node(int num)
 {
 	char s[12];
 	struct dentry *root = devpts_root;
 	mutex_lock(&root->d_inode->i_mutex);
 	return lookup_one_len(s, root, sprintf(s, "%d", num));
 }

 int devpts_new_index(void)
 {
 	int index;
 	int ida_ret;

 retry:
 	if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) {
 		return -ENOMEM;
 	}

 	mutex_lock(&allocated_ptys_lock);
 	ida_ret = ida_get_new(&allocated_ptys, &index);
 	if (ida_ret < 0) {
 		mutex_unlock(&allocated_ptys_lock);
 		if (ida_ret == -EAGAIN)
 			goto retry;
 		return -EIO;
 	}

 	if (index >= pty_limit) {
 		ida_remove(&allocated_ptys, index);
 		mutex_unlock(&allocated_ptys_lock);
 		return -EIO;
 	}
 	mutex_unlock(&allocated_ptys_lock);
 	return index;
 }

 void devpts_kill_index(int idx)
 {
 	mutex_lock(&allocated_ptys_lock);
 	ida_remove(&allocated_ptys, idx);
 	mutex_unlock(&allocated_ptys_lock);
 }

 int devpts_pty_new(struct tty_struct *tty)
 {
 	int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
 	struct tty_driver *driver = tty->driver;
 	dev_t device = MKDEV(driver->major, driver->minor_start+number);
 	struct dentry *dentry;
 	struct inode *inode = new_inode(devpts_mnt->mnt_sb);

 	/* We're supposed to be given the slave end of a pty */
 	BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
 	BUG_ON(driver->subtype != PTY_TYPE_SLAVE);

 	if (!inode)
 		return -ENOMEM;

 	inode->i_ino = number+2;
 	inode->i_uid = config.setuid ? config.uid : current->fsuid;
 	inode->i_gid = config.setgid ? config.gid : current->fsgid;
 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 	init_special_inode(inode, S_IFCHR|config.mode, device);
 	inode->i_private = tty;

 	dentry = get_node(number);
 	if (!IS_ERR(dentry) && !dentry->d_inode) {
 		d_instantiate(dentry, inode);
 		fsnotify_create(devpts_root->d_inode, dentry);
 	}

 	mutex_unlock(&devpts_root->d_inode->i_mutex);

 	return 0;
 }

 struct tty_struct *devpts_get_tty(int number)
 {
 	struct dentry *dentry = get_node(number);
 	struct tty_struct *tty;

 	tty = NULL;
 	if (!IS_ERR(dentry)) {
 		if (dentry->d_inode)
 			tty = dentry->d_inode->i_private;
 		dput(dentry);
 	}

 	mutex_unlock(&devpts_root->d_inode->i_mutex);

 	return tty;
 }

 void devpts_pty_kill(int number)
 {
 	struct dentry *dentry = get_node(number);

 	if (!IS_ERR(dentry)) {
 		struct inode *inode = dentry->d_inode;
 		if (inode) {
 			inode->i_nlink--;
 			d_delete(dentry);
 			dput(dentry);
 		}
 		dput(dentry);
 	}
 	mutex_unlock(&devpts_root->d_inode->i_mutex);
 }

 static int __init init_devpts_fs(void)
 {
 	int err = register_filesystem(&devpts_fs_type);
 	if (!err) {
 		devpts_mnt = kern_mount(&devpts_fs_type);
 		if (IS_ERR(devpts_mnt))
 			err = PTR_ERR(devpts_mnt);
 	}
 	return err;
 }

 static void __exit exit_devpts_fs(void)
 {
 	unregister_filesystem(&devpts_fs_type);
 	mntput(devpts_mnt);
 }

 module_init(init_devpts_fs)
 module_exit(exit_devpts_fs)
 MODULE_LICENSE("GPL");
	/* -- linux-c -- --------------------------------------------------------- *
	*
	* linux/fs/devpts/inode.c
	*
	* Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
	*
	* This file is part of the Linux kernel and is made available under
	* the terms of the GNU General Public License, version 2, or at your
	* option, any later version, incorporated herein by reference.
	*
	* ------------------------------------------------------------------------- */

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/fs.h>
	#include <linux/sched.h>
	#include <linux/namei.h>
	#include <linux/mount.h>
	#include <linux/tty.h>
	#include <linux/mutex.h>
	#include <linux/idr.h>
	#include <linux/devpts_fs.h>
	#include <linux/parser.h>
	#include <linux/fsnotify.h>
	#include <linux/seq_file.h>

	#define DEVPTS_SUPER_MAGIC 0x1cd1

	#define DEVPTS_DEFAULT_MODE 0600

	extern int pty_limit; /* Config limit on Unix98 ptys */
	static DEFINE_IDA(allocated_ptys);
	static DEFINE_MUTEX(allocated_ptys_lock);

	static struct vfsmount *devpts_mnt;
	static struct dentry *devpts_root;

	static struct {
	int setuid;
	int setgid;
	uid_t uid;
	gid_t gid;
	umode_t mode;
	} config = {.mode = DEVPTS_DEFAULT_MODE};

	enum {
	Opt_uid, Opt_gid, Opt_mode,
	Opt_err
	};

	static match_table_t tokens = {
	{Opt_uid, "uid=%u"},
	{Opt_gid, "gid=%u"},
	{Opt_mode, "mode=%o"},
	{Opt_err, NULL}
	};

	static int devpts_remount(struct super_block sb, int flags, char *data)
	{
	char *p;

	config.setuid = 0;
	config.setgid = 0;
	config.uid = 0;
	config.gid = 0;
	config.mode = DEVPTS_DEFAULT_MODE;

	while ((p = strsep(&data, ",")) != NULL) {
	substring_t args[MAX_OPT_ARGS];
	int token;
	int option;

	if (!*p)
	continue;

	token = match_token(p, tokens, args);
	switch (token) {
	case Opt_uid:
	if (match_int(&args[0], &option))
	return -EINVAL;
	config.uid = option;
	config.setuid = 1;
	break;
	case Opt_gid:
	if (match_int(&args[0], &option))
	return -EINVAL;
	config.gid = option;
	config.setgid = 1;
	break;
	case Opt_mode:
	if (match_octal(&args[0], &option))
	return -EINVAL;
	config.mode = option & S_IALLUGO;
	break;
	default:
	printk(KERN_ERR "devpts: called with bogus options\n");
	return -EINVAL;
	}
	}

	return 0;
	}

	static int devpts_show_options(struct seq_file seq, struct vfsmount vfs)
	{
	if (config.setuid)
	seq_printf(seq, ",uid=%u", config.uid);
	if (config.setgid)
	seq_printf(seq, ",gid=%u", config.gid);
	seq_printf(seq, ",mode=%03o", config.mode);

	return 0;
	}

	static const struct super_operations devpts_sops = {
	.statfs = simple_statfs,
	.remount_fs = devpts_remount,
	.show_options = devpts_show_options,
	};

	static int
	devpts_fill_super(struct super_block s, void data, int silent)
	{
	struct inode * inode;

	s->s_blocksize = 1024;
	s->s_blocksize_bits = 10;
	s->s_magic = DEVPTS_SUPER_MAGIC;
	s->s_op = &devpts_sops;
	s->s_time_gran = 1;

	inode = new_inode(s);
	if (!inode)
	goto fail;
	inode->i_ino = 1;
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	inode->i_blocks = 0;
	inode->i_uid = inode->i_gid = 0;
	inode->i_mode = S_IFDIR \| S_IRUGO \| S_IXUGO \| S_IWUSR;
	inode->i_op = &simple_dir_inode_operations;
	inode->i_fop = &simple_dir_operations;
	inode->i_nlink = 2;

	devpts_root = s->s_root = d_alloc_root(inode);
	if (s->s_root)
	return 0;

	printk("devpts: get root dentry failed\n");
	iput(inode);
	fail:
	return -ENOMEM;
	}

	static int devpts_get_sb(struct file_system_type *fs_type,
	int flags, const char dev_name, void data, struct vfsmount *mnt)
	{
	return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
	}

	static struct file_system_type devpts_fs_type = {
	.owner = THIS_MODULE,
	.name = "devpts",
	.get_sb = devpts_get_sb,
	.kill_sb = kill_anon_super,
	};

	/*
	* The normal naming convention is simply /dev/pts/<number>; this conforms
	* to the System V naming convention
	*/

	static struct dentry *get_node(int num)
	{
	char s[12];
	struct dentry *root = devpts_root;
	mutex_lock(&root->d_inode->i_mutex);
	return lookup_one_len(s, root, sprintf(s, "%d", num));
	}

	int devpts_new_index(void)
	{
	int index;
	int ida_ret;

	retry:
	if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) {
	return -ENOMEM;
	}

	mutex_lock(&allocated_ptys_lock);
	ida_ret = ida_get_new(&allocated_ptys, &index);
	if (ida_ret < 0) {
	mutex_unlock(&allocated_ptys_lock);
	if (ida_ret == -EAGAIN)
	goto retry;
	return -EIO;
	}

	if (index >= pty_limit) {
	ida_remove(&allocated_ptys, index);
	mutex_unlock(&allocated_ptys_lock);
	return -EIO;
	}
	mutex_unlock(&allocated_ptys_lock);
	return index;
	}

	void devpts_kill_index(int idx)
	{
	mutex_lock(&allocated_ptys_lock);
	ida_remove(&allocated_ptys, idx);
	mutex_unlock(&allocated_ptys_lock);
	}

	int devpts_pty_new(struct tty_struct *tty)
	{
	int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
	struct tty_driver *driver = tty->driver;
	dev_t device = MKDEV(driver->major, driver->minor_start+number);
	struct dentry *dentry;
	struct inode *inode = new_inode(devpts_mnt->mnt_sb);

	/* We're supposed to be given the slave end of a pty */
	BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
	BUG_ON(driver->subtype != PTY_TYPE_SLAVE);

	if (!inode)
	return -ENOMEM;

	inode->i_ino = number+2;
	inode->i_uid = config.setuid ? config.uid : current->fsuid;
	inode->i_gid = config.setgid ? config.gid : current->fsgid;
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	init_special_inode(inode, S_IFCHR\|config.mode, device);
	inode->i_private = tty;

	dentry = get_node(number);
	if (!IS_ERR(dentry) && !dentry->d_inode) {
	d_instantiate(dentry, inode);
	fsnotify_create(devpts_root->d_inode, dentry);
	}

	mutex_unlock(&devpts_root->d_inode->i_mutex);

	return 0;
	}

	struct tty_struct *devpts_get_tty(int number)
	{
	struct dentry *dentry = get_node(number);
	struct tty_struct *tty;

	tty = NULL;
	if (!IS_ERR(dentry)) {
	if (dentry->d_inode)
	tty = dentry->d_inode->i_private;
	dput(dentry);
	}

	mutex_unlock(&devpts_root->d_inode->i_mutex);

	return tty;
	}

	void devpts_pty_kill(int number)
	{
	struct dentry *dentry = get_node(number);

	if (!IS_ERR(dentry)) {
	struct inode *inode = dentry->d_inode;
	if (inode) {
	inode->i_nlink--;
	d_delete(dentry);
	dput(dentry);
	}
	dput(dentry);
	}
	mutex_unlock(&devpts_root->d_inode->i_mutex);
	}

	static int __init init_devpts_fs(void)
	{
	int err = register_filesystem(&devpts_fs_type);
	if (!err) {
	devpts_mnt = kern_mount(&devpts_fs_type);
	if (IS_ERR(devpts_mnt))
	err = PTR_ERR(devpts_mnt);
	}
	return err;
	}

	static void __exit exit_devpts_fs(void)
	{
	unregister_filesystem(&devpts_fs_type);
	mntput(devpts_mnt);
	}

	module_init(init_devpts_fs)
	module_exit(exit_devpts_fs)
	MODULE_LICENSE("GPL");