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 */ 33718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 34718a9163SSukadev Bhattiprolu 351da177e4SLinus Torvalds static struct vfsmount *devpts_mnt; 361da177e4SLinus Torvalds 371da177e4SLinus Torvalds static struct { 381da177e4SLinus Torvalds int setuid; 391da177e4SLinus Torvalds int setgid; 401da177e4SLinus Torvalds uid_t uid; 411da177e4SLinus Torvalds gid_t gid; 421da177e4SLinus Torvalds umode_t mode; 43b87a267eSMiklos Szeredi } config = {.mode = DEVPTS_DEFAULT_MODE}; 441da177e4SLinus Torvalds 457a673c6bSDomen Puncer enum { 467a673c6bSDomen Puncer Opt_uid, Opt_gid, Opt_mode, 477a673c6bSDomen Puncer Opt_err 487a673c6bSDomen Puncer }; 497a673c6bSDomen Puncer 50a447c093SSteven Whitehouse static const match_table_t tokens = { 517a673c6bSDomen Puncer {Opt_uid, "uid=%u"}, 527a673c6bSDomen Puncer {Opt_gid, "gid=%u"}, 537a673c6bSDomen Puncer {Opt_mode, "mode=%o"}, 547a673c6bSDomen Puncer {Opt_err, NULL} 557a673c6bSDomen Puncer }; 567a673c6bSDomen Puncer 57e76b7c01SSukadev Bhattiprolu struct pts_fs_info { 58e76b7c01SSukadev Bhattiprolu struct ida allocated_ptys; 59e76b7c01SSukadev Bhattiprolu }; 60e76b7c01SSukadev Bhattiprolu 61e76b7c01SSukadev Bhattiprolu static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) 62e76b7c01SSukadev Bhattiprolu { 63e76b7c01SSukadev Bhattiprolu return sb->s_fs_info; 64e76b7c01SSukadev Bhattiprolu } 65e76b7c01SSukadev Bhattiprolu 6659e55e6cSSukadev Bhattiprolu static inline struct super_block *pts_sb_from_inode(struct inode *inode) 6759e55e6cSSukadev Bhattiprolu { 6859e55e6cSSukadev Bhattiprolu if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 6959e55e6cSSukadev Bhattiprolu return inode->i_sb; 7059e55e6cSSukadev Bhattiprolu 7159e55e6cSSukadev Bhattiprolu return devpts_mnt->mnt_sb; 7259e55e6cSSukadev Bhattiprolu } 7359e55e6cSSukadev Bhattiprolu 741da177e4SLinus Torvalds static int devpts_remount(struct super_block *sb, int *flags, char *data) 751da177e4SLinus Torvalds { 767a673c6bSDomen Puncer char *p; 771da177e4SLinus Torvalds 787a673c6bSDomen Puncer config.setuid = 0; 797a673c6bSDomen Puncer config.setgid = 0; 807a673c6bSDomen Puncer config.uid = 0; 817a673c6bSDomen Puncer config.gid = 0; 82b87a267eSMiklos Szeredi config.mode = DEVPTS_DEFAULT_MODE; 837a673c6bSDomen Puncer 847a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 857a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 867a673c6bSDomen Puncer int token; 877a673c6bSDomen Puncer int option; 887a673c6bSDomen Puncer 897a673c6bSDomen Puncer if (!*p) 901da177e4SLinus Torvalds continue; 917a673c6bSDomen Puncer 927a673c6bSDomen Puncer token = match_token(p, tokens, args); 937a673c6bSDomen Puncer switch (token) { 947a673c6bSDomen Puncer case Opt_uid: 957a673c6bSDomen Puncer if (match_int(&args[0], &option)) 967a673c6bSDomen Puncer return -EINVAL; 977a673c6bSDomen Puncer config.uid = option; 987a673c6bSDomen Puncer config.setuid = 1; 997a673c6bSDomen Puncer break; 1007a673c6bSDomen Puncer case Opt_gid: 1017a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1027a673c6bSDomen Puncer return -EINVAL; 1037a673c6bSDomen Puncer config.gid = option; 1047a673c6bSDomen Puncer config.setgid = 1; 1057a673c6bSDomen Puncer break; 1067a673c6bSDomen Puncer case Opt_mode: 1077a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 1087a673c6bSDomen Puncer return -EINVAL; 109b87a267eSMiklos Szeredi config.mode = option & S_IALLUGO; 1107a673c6bSDomen Puncer break; 1117a673c6bSDomen Puncer default: 1127a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 1131da177e4SLinus Torvalds return -EINVAL; 1141da177e4SLinus Torvalds } 1151da177e4SLinus Torvalds } 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds return 0; 1181da177e4SLinus Torvalds } 1191da177e4SLinus Torvalds 120b87a267eSMiklos Szeredi static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) 121b87a267eSMiklos Szeredi { 122b87a267eSMiklos Szeredi if (config.setuid) 123b87a267eSMiklos Szeredi seq_printf(seq, ",uid=%u", config.uid); 124b87a267eSMiklos Szeredi if (config.setgid) 125b87a267eSMiklos Szeredi seq_printf(seq, ",gid=%u", config.gid); 126b87a267eSMiklos Szeredi seq_printf(seq, ",mode=%03o", config.mode); 127b87a267eSMiklos Szeredi 128b87a267eSMiklos Szeredi return 0; 129b87a267eSMiklos Szeredi } 130b87a267eSMiklos Szeredi 131ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 1321da177e4SLinus Torvalds .statfs = simple_statfs, 1331da177e4SLinus Torvalds .remount_fs = devpts_remount, 134b87a267eSMiklos Szeredi .show_options = devpts_show_options, 1351da177e4SLinus Torvalds }; 1361da177e4SLinus Torvalds 137e76b7c01SSukadev Bhattiprolu static void *new_pts_fs_info(void) 138e76b7c01SSukadev Bhattiprolu { 139e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 140e76b7c01SSukadev Bhattiprolu 141e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 142e76b7c01SSukadev Bhattiprolu if (!fsi) 143e76b7c01SSukadev Bhattiprolu return NULL; 144e76b7c01SSukadev Bhattiprolu 145e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 146e76b7c01SSukadev Bhattiprolu 147e76b7c01SSukadev Bhattiprolu return fsi; 148e76b7c01SSukadev Bhattiprolu } 149e76b7c01SSukadev Bhattiprolu 1501da177e4SLinus Torvalds static int 1511da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 1521da177e4SLinus Torvalds { 1531da177e4SLinus Torvalds struct inode * inode; 1541da177e4SLinus Torvalds 1551da177e4SLinus Torvalds s->s_blocksize = 1024; 1561da177e4SLinus Torvalds s->s_blocksize_bits = 10; 1571da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 1581da177e4SLinus Torvalds s->s_op = &devpts_sops; 1591da177e4SLinus Torvalds s->s_time_gran = 1; 1601da177e4SLinus Torvalds 161e76b7c01SSukadev Bhattiprolu s->s_fs_info = new_pts_fs_info(); 162e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 163e76b7c01SSukadev Bhattiprolu goto fail; 164e76b7c01SSukadev Bhattiprolu 1651da177e4SLinus Torvalds inode = new_inode(s); 1661da177e4SLinus Torvalds if (!inode) 167e76b7c01SSukadev Bhattiprolu goto free_fsi; 1681da177e4SLinus Torvalds inode->i_ino = 1; 1691da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 1701da177e4SLinus Torvalds inode->i_blocks = 0; 1711da177e4SLinus Torvalds inode->i_uid = inode->i_gid = 0; 1721da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 1731da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 1741da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 1751da177e4SLinus Torvalds inode->i_nlink = 2; 1761da177e4SLinus Torvalds 17759e55e6cSSukadev Bhattiprolu s->s_root = d_alloc_root(inode); 1781da177e4SLinus Torvalds if (s->s_root) 1791da177e4SLinus Torvalds return 0; 1801da177e4SLinus Torvalds 1811da177e4SLinus Torvalds printk("devpts: get root dentry failed\n"); 1821da177e4SLinus Torvalds iput(inode); 183e76b7c01SSukadev Bhattiprolu 184e76b7c01SSukadev Bhattiprolu free_fsi: 185e76b7c01SSukadev Bhattiprolu kfree(s->s_fs_info); 1861da177e4SLinus Torvalds fail: 1871da177e4SLinus Torvalds return -ENOMEM; 1881da177e4SLinus Torvalds } 1891da177e4SLinus Torvalds 190454e2398SDavid Howells static int devpts_get_sb(struct file_system_type *fs_type, 191454e2398SDavid Howells int flags, const char *dev_name, void *data, struct vfsmount *mnt) 1921da177e4SLinus Torvalds { 193454e2398SDavid Howells return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); 1941da177e4SLinus Torvalds } 1951da177e4SLinus Torvalds 196e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 197e76b7c01SSukadev Bhattiprolu { 198e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 199e76b7c01SSukadev Bhattiprolu 200e76b7c01SSukadev Bhattiprolu kfree(fsi); 201e76b7c01SSukadev Bhattiprolu kill_anon_super(sb); 202e76b7c01SSukadev Bhattiprolu } 203e76b7c01SSukadev Bhattiprolu 2041da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 2051da177e4SLinus Torvalds .owner = THIS_MODULE, 2061da177e4SLinus Torvalds .name = "devpts", 2071da177e4SLinus Torvalds .get_sb = devpts_get_sb, 208e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 2091da177e4SLinus Torvalds }; 2101da177e4SLinus Torvalds 2111da177e4SLinus Torvalds /* 2121da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 2131da177e4SLinus Torvalds * to the System V naming convention 2141da177e4SLinus Torvalds */ 2151da177e4SLinus Torvalds 21615f1a633SSukadev Bhattiprolu int devpts_new_index(struct inode *ptmx_inode) 217718a9163SSukadev Bhattiprolu { 218e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 219e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 220718a9163SSukadev Bhattiprolu int index; 2217ee7c12bSAlexey Dobriyan int ida_ret; 222718a9163SSukadev Bhattiprolu 223718a9163SSukadev Bhattiprolu retry: 224e76b7c01SSukadev Bhattiprolu if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) { 225718a9163SSukadev Bhattiprolu return -ENOMEM; 226718a9163SSukadev Bhattiprolu } 227718a9163SSukadev Bhattiprolu 228718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 229e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 2307ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 231718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 2327ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 233718a9163SSukadev Bhattiprolu goto retry; 234718a9163SSukadev Bhattiprolu return -EIO; 235718a9163SSukadev Bhattiprolu } 236718a9163SSukadev Bhattiprolu 237718a9163SSukadev Bhattiprolu if (index >= pty_limit) { 238e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 239718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 240718a9163SSukadev Bhattiprolu return -EIO; 241718a9163SSukadev Bhattiprolu } 242718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 243718a9163SSukadev Bhattiprolu return index; 244718a9163SSukadev Bhattiprolu } 245718a9163SSukadev Bhattiprolu 24615f1a633SSukadev Bhattiprolu void devpts_kill_index(struct inode *ptmx_inode, int idx) 247718a9163SSukadev Bhattiprolu { 248e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 249e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 250e76b7c01SSukadev Bhattiprolu 251718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 252e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 253718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 254718a9163SSukadev Bhattiprolu } 255718a9163SSukadev Bhattiprolu 25615f1a633SSukadev Bhattiprolu int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) 2571da177e4SLinus Torvalds { 258718a9163SSukadev Bhattiprolu int number = tty->index; /* tty layer puts index from devpts_new_index() in here */ 2591da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 2601da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 2611da177e4SLinus Torvalds struct dentry *dentry; 26259e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 26359e55e6cSSukadev Bhattiprolu struct inode *inode = new_inode(sb); 26459e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 26589a52e10SSukadev Bhattiprolu char s[12]; 2661da177e4SLinus Torvalds 2671da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 2681da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 2691da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 2701da177e4SLinus Torvalds 2711da177e4SLinus Torvalds if (!inode) 2721da177e4SLinus Torvalds return -ENOMEM; 2731da177e4SLinus Torvalds 2741da177e4SLinus Torvalds inode->i_ino = number+2; 275ec4c2aacSDavid Howells inode->i_uid = config.setuid ? config.uid : current_fsuid(); 276ec4c2aacSDavid Howells inode->i_gid = config.setgid ? config.gid : current_fsgid(); 2771da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 2781da177e4SLinus Torvalds init_special_inode(inode, S_IFCHR|config.mode, device); 2798e18e294STheodore Ts'o inode->i_private = tty; 280a6f37daaSSukadev Bhattiprolu tty->driver_data = inode; 2811da177e4SLinus Torvalds 28289a52e10SSukadev Bhattiprolu sprintf(s, "%d", number); 28389a52e10SSukadev Bhattiprolu 28459e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 28589a52e10SSukadev Bhattiprolu 28659e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 28789a52e10SSukadev Bhattiprolu if (!IS_ERR(dentry)) { 28889a52e10SSukadev Bhattiprolu d_add(dentry, inode); 28959e55e6cSSukadev Bhattiprolu fsnotify_create(root->d_inode, dentry); 2903972b7f6SFlorin Malita } 2911da177e4SLinus Torvalds 29259e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 2931da177e4SLinus Torvalds 2941da177e4SLinus Torvalds return 0; 2951da177e4SLinus Torvalds } 2961da177e4SLinus Torvalds 29715f1a633SSukadev Bhattiprolu struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) 2981da177e4SLinus Torvalds { 299527b3e47SSukadev Bhattiprolu BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 3001da177e4SLinus Torvalds 301527b3e47SSukadev Bhattiprolu if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 302527b3e47SSukadev Bhattiprolu return (struct tty_struct *)pts_inode->i_private; 303527b3e47SSukadev Bhattiprolu return NULL; 3041da177e4SLinus Torvalds } 3051da177e4SLinus Torvalds 30615f1a633SSukadev Bhattiprolu void devpts_pty_kill(struct tty_struct *tty) 3071da177e4SLinus Torvalds { 308a6f37daaSSukadev Bhattiprolu struct inode *inode = tty->driver_data; 30959e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(inode); 31059e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 311a6f37daaSSukadev Bhattiprolu struct dentry *dentry; 3121da177e4SLinus Torvalds 313a6f37daaSSukadev Bhattiprolu BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 314a6f37daaSSukadev Bhattiprolu 31559e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 316a6f37daaSSukadev Bhattiprolu 317a6f37daaSSukadev Bhattiprolu dentry = d_find_alias(inode); 318a6f37daaSSukadev Bhattiprolu if (dentry && !IS_ERR(dentry)) { 3191da177e4SLinus Torvalds inode->i_nlink--; 3201da177e4SLinus Torvalds d_delete(dentry); 3211da177e4SLinus Torvalds dput(dentry); 3221da177e4SLinus Torvalds } 323a6f37daaSSukadev Bhattiprolu 32459e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 3251da177e4SLinus Torvalds } 3261da177e4SLinus Torvalds 3271da177e4SLinus Torvalds static int __init init_devpts_fs(void) 3281da177e4SLinus Torvalds { 3291da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 3301da177e4SLinus Torvalds if (!err) { 3311da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 3321da177e4SLinus Torvalds if (IS_ERR(devpts_mnt)) 3331da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 3341da177e4SLinus Torvalds } 3351da177e4SLinus Torvalds return err; 3361da177e4SLinus Torvalds } 3371da177e4SLinus Torvalds 3381da177e4SLinus Torvalds static void __exit exit_devpts_fs(void) 3391da177e4SLinus Torvalds { 3401da177e4SLinus Torvalds unregister_filesystem(&devpts_fs_type); 3411da177e4SLinus Torvalds mntput(devpts_mnt); 3421da177e4SLinus Torvalds } 3431da177e4SLinus Torvalds 3441da177e4SLinus Torvalds module_init(init_devpts_fs) 3451da177e4SLinus Torvalds module_exit(exit_devpts_fs) 3461da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 347