| /* -*- 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 |
| #define PTMX_MINOR 2 |
| |
| 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(struct inode *ptmx_inode) |
| { |
| 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(struct inode *ptmx_inode, int idx) |
| { |
| mutex_lock(&allocated_ptys_lock); |
| ida_remove(&allocated_ptys, idx); |
| mutex_unlock(&allocated_ptys_lock); |
| } |
| |
| int devpts_pty_new(struct inode *ptmx_inode, 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); |
| char s[12]; |
| |
| /* 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; |
| |
| sprintf(s, "%d", number); |
| |
| mutex_lock(&devpts_root->d_inode->i_mutex); |
| |
| dentry = d_alloc_name(devpts_root, s); |
| if (!IS_ERR(dentry)) { |
| d_add(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(struct inode *pts_inode, int number) |
| { |
| BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); |
| |
| if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) |
| return (struct tty_struct *)pts_inode->i_private; |
| return NULL; |
| } |
| |
| void devpts_pty_kill(struct tty_struct *tty) |
| { |
| int number = tty->index; |
| 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"); |