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 30527b3e47SSukadev Bhattiprolu #define PTMX_MINOR 2 31b87a267eSMiklos Szeredi 32718a9163SSukadev Bhattiprolu extern int pty_limit; /* Config limit on Unix98 ptys */ 337ee7c12bSAlexey Dobriyan static DEFINE_IDA(allocated_ptys); 34718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 35718a9163SSukadev Bhattiprolu 361da177e4SLinus Torvalds static struct vfsmount *devpts_mnt; 371da177e4SLinus Torvalds static struct dentry *devpts_root; 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds static struct { 401da177e4SLinus Torvalds int setuid; 411da177e4SLinus Torvalds int setgid; 421da177e4SLinus Torvalds uid_t uid; 431da177e4SLinus Torvalds gid_t gid; 441da177e4SLinus Torvalds umode_t mode; 45b87a267eSMiklos Szeredi } config = {.mode = DEVPTS_DEFAULT_MODE}; 461da177e4SLinus Torvalds 477a673c6bSDomen Puncer enum { 487a673c6bSDomen Puncer Opt_uid, Opt_gid, Opt_mode, 497a673c6bSDomen Puncer Opt_err 507a673c6bSDomen Puncer }; 517a673c6bSDomen Puncer 527a673c6bSDomen Puncer static match_table_t tokens = { 537a673c6bSDomen Puncer {Opt_uid, "uid=%u"}, 547a673c6bSDomen Puncer {Opt_gid, "gid=%u"}, 557a673c6bSDomen Puncer {Opt_mode, "mode=%o"}, 567a673c6bSDomen Puncer {Opt_err, NULL} 577a673c6bSDomen Puncer }; 587a673c6bSDomen Puncer 591da177e4SLinus Torvalds static int devpts_remount(struct super_block *sb, int *flags, char *data) 601da177e4SLinus Torvalds { 617a673c6bSDomen Puncer char *p; 621da177e4SLinus Torvalds 637a673c6bSDomen Puncer config.setuid = 0; 647a673c6bSDomen Puncer config.setgid = 0; 657a673c6bSDomen Puncer config.uid = 0; 667a673c6bSDomen Puncer config.gid = 0; 67b87a267eSMiklos Szeredi config.mode = DEVPTS_DEFAULT_MODE; 687a673c6bSDomen Puncer 697a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 707a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 717a673c6bSDomen Puncer int token; 727a673c6bSDomen Puncer int option; 737a673c6bSDomen Puncer 747a673c6bSDomen Puncer if (!*p) 751da177e4SLinus Torvalds continue; 767a673c6bSDomen Puncer 777a673c6bSDomen Puncer token = match_token(p, tokens, args); 787a673c6bSDomen Puncer switch (token) { 797a673c6bSDomen Puncer case Opt_uid: 807a673c6bSDomen Puncer if (match_int(&args[0], &option)) 817a673c6bSDomen Puncer return -EINVAL; 827a673c6bSDomen Puncer config.uid = option; 837a673c6bSDomen Puncer config.setuid = 1; 847a673c6bSDomen Puncer break; 857a673c6bSDomen Puncer case Opt_gid: 867a673c6bSDomen Puncer if (match_int(&args[0], &option)) 877a673c6bSDomen Puncer return -EINVAL; 887a673c6bSDomen Puncer config.gid = option; 897a673c6bSDomen Puncer config.setgid = 1; 907a673c6bSDomen Puncer break; 917a673c6bSDomen Puncer case Opt_mode: 927a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 937a673c6bSDomen Puncer return -EINVAL; 94b87a267eSMiklos Szeredi config.mode = option & S_IALLUGO; 957a673c6bSDomen Puncer break; 967a673c6bSDomen Puncer default: 977a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 981da177e4SLinus Torvalds return -EINVAL; 991da177e4SLinus Torvalds } 1001da177e4SLinus Torvalds } 1011da177e4SLinus Torvalds 1021da177e4SLinus Torvalds return 0; 1031da177e4SLinus Torvalds } 1041da177e4SLinus Torvalds 105b87a267eSMiklos Szeredi static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) 106b87a267eSMiklos Szeredi { 107b87a267eSMiklos Szeredi if (config.setuid) 108b87a267eSMiklos Szeredi seq_printf(seq, ",uid=%u", config.uid); 109b87a267eSMiklos Szeredi if (config.setgid) 110b87a267eSMiklos Szeredi seq_printf(seq, ",gid=%u", config.gid); 111b87a267eSMiklos Szeredi seq_printf(seq, ",mode=%03o", config.mode); 112b87a267eSMiklos Szeredi 113b87a267eSMiklos Szeredi return 0; 114b87a267eSMiklos Szeredi } 115b87a267eSMiklos Szeredi 116ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 1171da177e4SLinus Torvalds .statfs = simple_statfs, 1181da177e4SLinus Torvalds .remount_fs = devpts_remount, 119b87a267eSMiklos Szeredi .show_options = devpts_show_options, 1201da177e4SLinus Torvalds }; 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds static int 1231da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 1241da177e4SLinus Torvalds { 1251da177e4SLinus Torvalds struct inode * inode; 1261da177e4SLinus Torvalds 1271da177e4SLinus Torvalds s->s_blocksize = 1024; 1281da177e4SLinus Torvalds s->s_blocksize_bits = 10; 1291da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 1301da177e4SLinus Torvalds s->s_op = &devpts_sops; 1311da177e4SLinus Torvalds s->s_time_gran = 1; 1321da177e4SLinus Torvalds 1331da177e4SLinus Torvalds inode = new_inode(s); 1341da177e4SLinus Torvalds if (!inode) 1351da177e4SLinus Torvalds goto fail; 1361da177e4SLinus Torvalds inode->i_ino = 1; 1371da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 1381da177e4SLinus Torvalds inode->i_blocks = 0; 1391da177e4SLinus Torvalds inode->i_uid = inode->i_gid = 0; 1401da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 1411da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 1421da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 1431da177e4SLinus Torvalds inode->i_nlink = 2; 1441da177e4SLinus Torvalds 1451da177e4SLinus Torvalds devpts_root = s->s_root = d_alloc_root(inode); 1461da177e4SLinus Torvalds if (s->s_root) 1471da177e4SLinus Torvalds return 0; 1481da177e4SLinus Torvalds 1491da177e4SLinus Torvalds printk("devpts: get root dentry failed\n"); 1501da177e4SLinus Torvalds iput(inode); 1511da177e4SLinus Torvalds fail: 1521da177e4SLinus Torvalds return -ENOMEM; 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds 155454e2398SDavid Howells static int devpts_get_sb(struct file_system_type *fs_type, 156454e2398SDavid Howells int flags, const char *dev_name, void *data, struct vfsmount *mnt) 1571da177e4SLinus Torvalds { 158454e2398SDavid Howells return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); 1591da177e4SLinus Torvalds } 1601da177e4SLinus Torvalds 1611da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 1621da177e4SLinus Torvalds .owner = THIS_MODULE, 1631da177e4SLinus Torvalds .name = "devpts", 1641da177e4SLinus Torvalds .get_sb = devpts_get_sb, 1651da177e4SLinus Torvalds .kill_sb = kill_anon_super, 1661da177e4SLinus Torvalds }; 1671da177e4SLinus Torvalds 1681da177e4SLinus Torvalds /* 1691da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 1701da177e4SLinus Torvalds * to the System V naming convention 1711da177e4SLinus Torvalds */ 1721da177e4SLinus Torvalds 1731da177e4SLinus Torvalds static struct dentry *get_node(int num) 1741da177e4SLinus Torvalds { 1751da177e4SLinus Torvalds char s[12]; 1761da177e4SLinus Torvalds struct dentry *root = devpts_root; 1771b1dcc1bSJes Sorensen mutex_lock(&root->d_inode->i_mutex); 1781da177e4SLinus Torvalds return lookup_one_len(s, root, sprintf(s, "%d", num)); 1791da177e4SLinus Torvalds } 1801da177e4SLinus Torvalds 18115f1a633SSukadev Bhattiprolu int devpts_new_index(struct inode *ptmx_inode) 182718a9163SSukadev Bhattiprolu { 183718a9163SSukadev Bhattiprolu int index; 1847ee7c12bSAlexey Dobriyan int ida_ret; 185718a9163SSukadev Bhattiprolu 186718a9163SSukadev Bhattiprolu retry: 1877ee7c12bSAlexey Dobriyan if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) { 188718a9163SSukadev Bhattiprolu return -ENOMEM; 189718a9163SSukadev Bhattiprolu } 190718a9163SSukadev Bhattiprolu 191718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 1927ee7c12bSAlexey Dobriyan ida_ret = ida_get_new(&allocated_ptys, &index); 1937ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 194718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 1957ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 196718a9163SSukadev Bhattiprolu goto retry; 197718a9163SSukadev Bhattiprolu return -EIO; 198718a9163SSukadev Bhattiprolu } 199718a9163SSukadev Bhattiprolu 200718a9163SSukadev Bhattiprolu if (index >= pty_limit) { 2017ee7c12bSAlexey Dobriyan ida_remove(&allocated_ptys, index); 202718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 203718a9163SSukadev Bhattiprolu return -EIO; 204718a9163SSukadev Bhattiprolu } 205718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 206718a9163SSukadev Bhattiprolu return index; 207718a9163SSukadev Bhattiprolu } 208718a9163SSukadev Bhattiprolu 20915f1a633SSukadev Bhattiprolu void devpts_kill_index(struct inode *ptmx_inode, int idx) 210718a9163SSukadev Bhattiprolu { 211718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 2127ee7c12bSAlexey Dobriyan ida_remove(&allocated_ptys, idx); 213718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 214718a9163SSukadev Bhattiprolu } 215718a9163SSukadev Bhattiprolu 21615f1a633SSukadev Bhattiprolu int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) 2171da177e4SLinus Torvalds { 218718a9163SSukadev Bhattiprolu int number = tty->index; /* tty layer puts index from devpts_new_index() in here */ 2191da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 2201da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 2211da177e4SLinus Torvalds struct dentry *dentry; 2221da177e4SLinus Torvalds struct inode *inode = new_inode(devpts_mnt->mnt_sb); 22389a52e10SSukadev Bhattiprolu char s[12]; 2241da177e4SLinus Torvalds 2251da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 2261da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 2271da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 2281da177e4SLinus Torvalds 2291da177e4SLinus Torvalds if (!inode) 2301da177e4SLinus Torvalds return -ENOMEM; 2311da177e4SLinus Torvalds 2321da177e4SLinus Torvalds inode->i_ino = number+2; 2331da177e4SLinus Torvalds inode->i_uid = config.setuid ? config.uid : current->fsuid; 2341da177e4SLinus Torvalds inode->i_gid = config.setgid ? config.gid : current->fsgid; 2351da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 2361da177e4SLinus Torvalds init_special_inode(inode, S_IFCHR|config.mode, device); 2378e18e294STheodore Ts'o inode->i_private = tty; 2381da177e4SLinus Torvalds 23989a52e10SSukadev Bhattiprolu sprintf(s, "%d", number); 24089a52e10SSukadev Bhattiprolu 24189a52e10SSukadev Bhattiprolu mutex_lock(&devpts_root->d_inode->i_mutex); 24289a52e10SSukadev Bhattiprolu 24389a52e10SSukadev Bhattiprolu dentry = d_alloc_name(devpts_root, s); 24489a52e10SSukadev Bhattiprolu if (!IS_ERR(dentry)) { 24589a52e10SSukadev Bhattiprolu d_add(dentry, inode); 2463972b7f6SFlorin Malita fsnotify_create(devpts_root->d_inode, dentry); 2473972b7f6SFlorin Malita } 2481da177e4SLinus Torvalds 2491b1dcc1bSJes Sorensen mutex_unlock(&devpts_root->d_inode->i_mutex); 2501da177e4SLinus Torvalds 2511da177e4SLinus Torvalds return 0; 2521da177e4SLinus Torvalds } 2531da177e4SLinus Torvalds 25415f1a633SSukadev Bhattiprolu struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) 2551da177e4SLinus Torvalds { 256527b3e47SSukadev Bhattiprolu BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 2571da177e4SLinus Torvalds 258527b3e47SSukadev Bhattiprolu if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 259527b3e47SSukadev Bhattiprolu return (struct tty_struct *)pts_inode->i_private; 260527b3e47SSukadev Bhattiprolu return NULL; 2611da177e4SLinus Torvalds } 2621da177e4SLinus Torvalds 26315f1a633SSukadev Bhattiprolu void devpts_pty_kill(struct tty_struct *tty) 2641da177e4SLinus Torvalds { 26515f1a633SSukadev Bhattiprolu int number = tty->index; 2661da177e4SLinus Torvalds struct dentry *dentry = get_node(number); 2671da177e4SLinus Torvalds 2681da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 2691da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 2701da177e4SLinus Torvalds if (inode) { 2711da177e4SLinus Torvalds inode->i_nlink--; 2721da177e4SLinus Torvalds d_delete(dentry); 2731da177e4SLinus Torvalds dput(dentry); 2741da177e4SLinus Torvalds } 2751da177e4SLinus Torvalds dput(dentry); 2761da177e4SLinus Torvalds } 2771b1dcc1bSJes Sorensen mutex_unlock(&devpts_root->d_inode->i_mutex); 2781da177e4SLinus Torvalds } 2791da177e4SLinus Torvalds 2801da177e4SLinus Torvalds static int __init init_devpts_fs(void) 2811da177e4SLinus Torvalds { 2821da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 2831da177e4SLinus Torvalds if (!err) { 2841da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 2851da177e4SLinus Torvalds if (IS_ERR(devpts_mnt)) 2861da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 2871da177e4SLinus Torvalds } 2881da177e4SLinus Torvalds return err; 2891da177e4SLinus Torvalds } 2901da177e4SLinus Torvalds 2911da177e4SLinus Torvalds static void __exit exit_devpts_fs(void) 2921da177e4SLinus Torvalds { 2931da177e4SLinus Torvalds unregister_filesystem(&devpts_fs_type); 2941da177e4SLinus Torvalds mntput(devpts_mnt); 2951da177e4SLinus Torvalds } 2961da177e4SLinus Torvalds 2971da177e4SLinus Torvalds module_init(init_devpts_fs) 2981da177e4SLinus Torvalds module_exit(exit_devpts_fs) 2991da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 300