11da177e4SLinus Torvalds /* -*- linux-c -*- --------------------------------------------------------- * 21da177e4SLinus Torvalds * 31da177e4SLinus Torvalds * linux/fs/devpts/inode.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * This file is part of the Linux kernel and is made available under 81da177e4SLinus Torvalds * the terms of the GNU General Public License, version 2, or at your 91da177e4SLinus Torvalds * option, any later version, incorporated herein by reference. 101da177e4SLinus Torvalds * 111da177e4SLinus Torvalds * ------------------------------------------------------------------------- */ 121da177e4SLinus Torvalds 131da177e4SLinus Torvalds #include <linux/module.h> 141da177e4SLinus Torvalds #include <linux/init.h> 151da177e4SLinus Torvalds #include <linux/fs.h> 161da177e4SLinus Torvalds #include <linux/sched.h> 171da177e4SLinus Torvalds #include <linux/namei.h> 181da177e4SLinus Torvalds #include <linux/mount.h> 191da177e4SLinus Torvalds #include <linux/tty.h> 20718a9163SSukadev Bhattiprolu #include <linux/mutex.h> 21718a9163SSukadev Bhattiprolu #include <linux/idr.h> 221da177e4SLinus Torvalds #include <linux/devpts_fs.h> 237a673c6bSDomen Puncer #include <linux/parser.h> 243972b7f6SFlorin Malita #include <linux/fsnotify.h> 25b87a267eSMiklos Szeredi #include <linux/seq_file.h> 261da177e4SLinus Torvalds 271da177e4SLinus Torvalds #define DEVPTS_SUPER_MAGIC 0x1cd1 281da177e4SLinus Torvalds 29b87a267eSMiklos Szeredi #define DEVPTS_DEFAULT_MODE 0600 30b87a267eSMiklos Szeredi 31718a9163SSukadev Bhattiprolu extern int pty_limit; /* Config limit on Unix98 ptys */ 32718a9163SSukadev Bhattiprolu static DEFINE_IDR(allocated_ptys); 33718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 34718a9163SSukadev Bhattiprolu 351da177e4SLinus Torvalds static struct vfsmount *devpts_mnt; 361da177e4SLinus Torvalds static struct dentry *devpts_root; 371da177e4SLinus Torvalds 381da177e4SLinus Torvalds static struct { 391da177e4SLinus Torvalds int setuid; 401da177e4SLinus Torvalds int setgid; 411da177e4SLinus Torvalds uid_t uid; 421da177e4SLinus Torvalds gid_t gid; 431da177e4SLinus Torvalds umode_t mode; 44b87a267eSMiklos Szeredi } config = {.mode = DEVPTS_DEFAULT_MODE}; 451da177e4SLinus Torvalds 467a673c6bSDomen Puncer enum { 477a673c6bSDomen Puncer Opt_uid, Opt_gid, Opt_mode, 487a673c6bSDomen Puncer Opt_err 497a673c6bSDomen Puncer }; 507a673c6bSDomen Puncer 517a673c6bSDomen Puncer static match_table_t tokens = { 527a673c6bSDomen Puncer {Opt_uid, "uid=%u"}, 537a673c6bSDomen Puncer {Opt_gid, "gid=%u"}, 547a673c6bSDomen Puncer {Opt_mode, "mode=%o"}, 557a673c6bSDomen Puncer {Opt_err, NULL} 567a673c6bSDomen Puncer }; 577a673c6bSDomen Puncer 581da177e4SLinus Torvalds static int devpts_remount(struct super_block *sb, int *flags, char *data) 591da177e4SLinus Torvalds { 607a673c6bSDomen Puncer char *p; 611da177e4SLinus Torvalds 627a673c6bSDomen Puncer config.setuid = 0; 637a673c6bSDomen Puncer config.setgid = 0; 647a673c6bSDomen Puncer config.uid = 0; 657a673c6bSDomen Puncer config.gid = 0; 66b87a267eSMiklos Szeredi config.mode = DEVPTS_DEFAULT_MODE; 677a673c6bSDomen Puncer 687a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 697a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 707a673c6bSDomen Puncer int token; 717a673c6bSDomen Puncer int option; 727a673c6bSDomen Puncer 737a673c6bSDomen Puncer if (!*p) 741da177e4SLinus Torvalds continue; 757a673c6bSDomen Puncer 767a673c6bSDomen Puncer token = match_token(p, tokens, args); 777a673c6bSDomen Puncer switch (token) { 787a673c6bSDomen Puncer case Opt_uid: 797a673c6bSDomen Puncer if (match_int(&args[0], &option)) 807a673c6bSDomen Puncer return -EINVAL; 817a673c6bSDomen Puncer config.uid = option; 827a673c6bSDomen Puncer config.setuid = 1; 837a673c6bSDomen Puncer break; 847a673c6bSDomen Puncer case Opt_gid: 857a673c6bSDomen Puncer if (match_int(&args[0], &option)) 867a673c6bSDomen Puncer return -EINVAL; 877a673c6bSDomen Puncer config.gid = option; 887a673c6bSDomen Puncer config.setgid = 1; 897a673c6bSDomen Puncer break; 907a673c6bSDomen Puncer case Opt_mode: 917a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 927a673c6bSDomen Puncer return -EINVAL; 93b87a267eSMiklos Szeredi config.mode = option & S_IALLUGO; 947a673c6bSDomen Puncer break; 957a673c6bSDomen Puncer default: 967a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 971da177e4SLinus Torvalds return -EINVAL; 981da177e4SLinus Torvalds } 991da177e4SLinus Torvalds } 1001da177e4SLinus Torvalds 1011da177e4SLinus Torvalds return 0; 1021da177e4SLinus Torvalds } 1031da177e4SLinus Torvalds 104b87a267eSMiklos Szeredi static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) 105b87a267eSMiklos Szeredi { 106b87a267eSMiklos Szeredi if (config.setuid) 107b87a267eSMiklos Szeredi seq_printf(seq, ",uid=%u", config.uid); 108b87a267eSMiklos Szeredi if (config.setgid) 109b87a267eSMiklos Szeredi seq_printf(seq, ",gid=%u", config.gid); 110b87a267eSMiklos Szeredi seq_printf(seq, ",mode=%03o", config.mode); 111b87a267eSMiklos Szeredi 112b87a267eSMiklos Szeredi return 0; 113b87a267eSMiklos Szeredi } 114b87a267eSMiklos Szeredi 115ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 1161da177e4SLinus Torvalds .statfs = simple_statfs, 1171da177e4SLinus Torvalds .remount_fs = devpts_remount, 118b87a267eSMiklos Szeredi .show_options = devpts_show_options, 1191da177e4SLinus Torvalds }; 1201da177e4SLinus Torvalds 1211da177e4SLinus Torvalds static int 1221da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 1231da177e4SLinus Torvalds { 1241da177e4SLinus Torvalds struct inode * inode; 1251da177e4SLinus Torvalds 1261da177e4SLinus Torvalds s->s_blocksize = 1024; 1271da177e4SLinus Torvalds s->s_blocksize_bits = 10; 1281da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 1291da177e4SLinus Torvalds s->s_op = &devpts_sops; 1301da177e4SLinus Torvalds s->s_time_gran = 1; 1311da177e4SLinus Torvalds 1321da177e4SLinus Torvalds inode = new_inode(s); 1331da177e4SLinus Torvalds if (!inode) 1341da177e4SLinus Torvalds goto fail; 1351da177e4SLinus Torvalds inode->i_ino = 1; 1361da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 1371da177e4SLinus Torvalds inode->i_blocks = 0; 1381da177e4SLinus Torvalds inode->i_uid = inode->i_gid = 0; 1391da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 1401da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 1411da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 1421da177e4SLinus Torvalds inode->i_nlink = 2; 1431da177e4SLinus Torvalds 1441da177e4SLinus Torvalds devpts_root = s->s_root = d_alloc_root(inode); 1451da177e4SLinus Torvalds if (s->s_root) 1461da177e4SLinus Torvalds return 0; 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds printk("devpts: get root dentry failed\n"); 1491da177e4SLinus Torvalds iput(inode); 1501da177e4SLinus Torvalds fail: 1511da177e4SLinus Torvalds return -ENOMEM; 1521da177e4SLinus Torvalds } 1531da177e4SLinus Torvalds 154454e2398SDavid Howells static int devpts_get_sb(struct file_system_type *fs_type, 155454e2398SDavid Howells int flags, const char *dev_name, void *data, struct vfsmount *mnt) 1561da177e4SLinus Torvalds { 157454e2398SDavid Howells return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 1601da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 1611da177e4SLinus Torvalds .owner = THIS_MODULE, 1621da177e4SLinus Torvalds .name = "devpts", 1631da177e4SLinus Torvalds .get_sb = devpts_get_sb, 1641da177e4SLinus Torvalds .kill_sb = kill_anon_super, 1651da177e4SLinus Torvalds }; 1661da177e4SLinus Torvalds 1671da177e4SLinus Torvalds /* 1681da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 1691da177e4SLinus Torvalds * to the System V naming convention 1701da177e4SLinus Torvalds */ 1711da177e4SLinus Torvalds 1721da177e4SLinus Torvalds static struct dentry *get_node(int num) 1731da177e4SLinus Torvalds { 1741da177e4SLinus Torvalds char s[12]; 1751da177e4SLinus Torvalds struct dentry *root = devpts_root; 1761b1dcc1bSJes Sorensen mutex_lock(&root->d_inode->i_mutex); 1771da177e4SLinus Torvalds return lookup_one_len(s, root, sprintf(s, "%d", num)); 1781da177e4SLinus Torvalds } 1791da177e4SLinus Torvalds 180718a9163SSukadev Bhattiprolu int devpts_new_index(void) 181718a9163SSukadev Bhattiprolu { 182718a9163SSukadev Bhattiprolu int index; 183718a9163SSukadev Bhattiprolu int idr_ret; 184718a9163SSukadev Bhattiprolu 185718a9163SSukadev Bhattiprolu retry: 186718a9163SSukadev Bhattiprolu if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) { 187718a9163SSukadev Bhattiprolu return -ENOMEM; 188718a9163SSukadev Bhattiprolu } 189718a9163SSukadev Bhattiprolu 190718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 191718a9163SSukadev Bhattiprolu idr_ret = idr_get_new(&allocated_ptys, NULL, &index); 192718a9163SSukadev Bhattiprolu if (idr_ret < 0) { 193718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 194718a9163SSukadev Bhattiprolu if (idr_ret == -EAGAIN) 195718a9163SSukadev Bhattiprolu goto retry; 196718a9163SSukadev Bhattiprolu return -EIO; 197718a9163SSukadev Bhattiprolu } 198718a9163SSukadev Bhattiprolu 199718a9163SSukadev Bhattiprolu if (index >= pty_limit) { 200718a9163SSukadev Bhattiprolu idr_remove(&allocated_ptys, index); 201718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 202718a9163SSukadev Bhattiprolu return -EIO; 203718a9163SSukadev Bhattiprolu } 204718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 205718a9163SSukadev Bhattiprolu return index; 206718a9163SSukadev Bhattiprolu } 207718a9163SSukadev Bhattiprolu 208718a9163SSukadev Bhattiprolu void devpts_kill_index(int idx) 209718a9163SSukadev Bhattiprolu { 210718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 211718a9163SSukadev Bhattiprolu idr_remove(&allocated_ptys, idx); 212718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 213718a9163SSukadev Bhattiprolu } 214718a9163SSukadev Bhattiprolu 2151da177e4SLinus Torvalds int devpts_pty_new(struct tty_struct *tty) 2161da177e4SLinus Torvalds { 217718a9163SSukadev Bhattiprolu int number = tty->index; /* tty layer puts index from devpts_new_index() in here */ 2181da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 2191da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 2201da177e4SLinus Torvalds struct dentry *dentry; 2211da177e4SLinus Torvalds struct inode *inode = new_inode(devpts_mnt->mnt_sb); 2221da177e4SLinus Torvalds 2231da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 2241da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 2251da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 2261da177e4SLinus Torvalds 2271da177e4SLinus Torvalds if (!inode) 2281da177e4SLinus Torvalds return -ENOMEM; 2291da177e4SLinus Torvalds 2301da177e4SLinus Torvalds inode->i_ino = number+2; 2311da177e4SLinus Torvalds inode->i_uid = config.setuid ? config.uid : current->fsuid; 2321da177e4SLinus Torvalds inode->i_gid = config.setgid ? config.gid : current->fsgid; 2331da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 2341da177e4SLinus Torvalds init_special_inode(inode, S_IFCHR|config.mode, device); 2358e18e294STheodore Ts'o inode->i_private = tty; 2361da177e4SLinus Torvalds 2371da177e4SLinus Torvalds dentry = get_node(number); 2383972b7f6SFlorin Malita if (!IS_ERR(dentry) && !dentry->d_inode) { 2391da177e4SLinus Torvalds d_instantiate(dentry, inode); 2403972b7f6SFlorin Malita fsnotify_create(devpts_root->d_inode, dentry); 2413972b7f6SFlorin Malita } 2421da177e4SLinus Torvalds 2431b1dcc1bSJes Sorensen mutex_unlock(&devpts_root->d_inode->i_mutex); 2441da177e4SLinus Torvalds 2451da177e4SLinus Torvalds return 0; 2461da177e4SLinus Torvalds } 2471da177e4SLinus Torvalds 2481da177e4SLinus Torvalds struct tty_struct *devpts_get_tty(int number) 2491da177e4SLinus Torvalds { 2501da177e4SLinus Torvalds struct dentry *dentry = get_node(number); 2511da177e4SLinus Torvalds struct tty_struct *tty; 2521da177e4SLinus Torvalds 2531da177e4SLinus Torvalds tty = NULL; 2541da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 2551da177e4SLinus Torvalds if (dentry->d_inode) 2568e18e294STheodore Ts'o tty = dentry->d_inode->i_private; 2571da177e4SLinus Torvalds dput(dentry); 2581da177e4SLinus Torvalds } 2591da177e4SLinus Torvalds 2601b1dcc1bSJes Sorensen mutex_unlock(&devpts_root->d_inode->i_mutex); 2611da177e4SLinus Torvalds 2621da177e4SLinus Torvalds return tty; 2631da177e4SLinus Torvalds } 2641da177e4SLinus Torvalds 2651da177e4SLinus Torvalds void devpts_pty_kill(int number) 2661da177e4SLinus Torvalds { 2671da177e4SLinus Torvalds struct dentry *dentry = get_node(number); 2681da177e4SLinus Torvalds 2691da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 2701da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 2711da177e4SLinus Torvalds if (inode) { 2721da177e4SLinus Torvalds inode->i_nlink--; 2731da177e4SLinus Torvalds d_delete(dentry); 2741da177e4SLinus Torvalds dput(dentry); 2751da177e4SLinus Torvalds } 2761da177e4SLinus Torvalds dput(dentry); 2771da177e4SLinus Torvalds } 2781b1dcc1bSJes Sorensen mutex_unlock(&devpts_root->d_inode->i_mutex); 2791da177e4SLinus Torvalds } 2801da177e4SLinus Torvalds 2811da177e4SLinus Torvalds static int __init init_devpts_fs(void) 2821da177e4SLinus Torvalds { 2831da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 2841da177e4SLinus Torvalds if (!err) { 2851da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 2861da177e4SLinus Torvalds if (IS_ERR(devpts_mnt)) 2871da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 2881da177e4SLinus Torvalds } 2891da177e4SLinus Torvalds return err; 2901da177e4SLinus Torvalds } 2911da177e4SLinus Torvalds 2921da177e4SLinus Torvalds static void __exit exit_devpts_fs(void) 2931da177e4SLinus Torvalds { 2941da177e4SLinus Torvalds unregister_filesystem(&devpts_fs_type); 2951da177e4SLinus Torvalds mntput(devpts_mnt); 2961da177e4SLinus Torvalds } 2971da177e4SLinus Torvalds 2981da177e4SLinus Torvalds module_init(init_devpts_fs) 2991da177e4SLinus Torvalds module_exit(exit_devpts_fs) 3001da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 301