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 3731af0abbSSukadev Bhattiprolu struct pts_mount_opts { 381da177e4SLinus Torvalds int setuid; 391da177e4SLinus Torvalds int setgid; 401da177e4SLinus Torvalds uid_t uid; 411da177e4SLinus Torvalds gid_t gid; 421da177e4SLinus Torvalds umode_t mode; 4331af0abbSSukadev Bhattiprolu }; 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; 5931af0abbSSukadev Bhattiprolu struct pts_mount_opts mount_opts; 60e76b7c01SSukadev Bhattiprolu }; 61e76b7c01SSukadev Bhattiprolu 62e76b7c01SSukadev Bhattiprolu static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) 63e76b7c01SSukadev Bhattiprolu { 64e76b7c01SSukadev Bhattiprolu return sb->s_fs_info; 65e76b7c01SSukadev Bhattiprolu } 66e76b7c01SSukadev Bhattiprolu 6759e55e6cSSukadev Bhattiprolu static inline struct super_block *pts_sb_from_inode(struct inode *inode) 6859e55e6cSSukadev Bhattiprolu { 6959e55e6cSSukadev Bhattiprolu if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 7059e55e6cSSukadev Bhattiprolu return inode->i_sb; 7159e55e6cSSukadev Bhattiprolu 7259e55e6cSSukadev Bhattiprolu return devpts_mnt->mnt_sb; 7359e55e6cSSukadev Bhattiprolu } 7459e55e6cSSukadev Bhattiprolu 751da177e4SLinus Torvalds static int devpts_remount(struct super_block *sb, int *flags, char *data) 761da177e4SLinus Torvalds { 777a673c6bSDomen Puncer char *p; 7831af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 7931af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 801da177e4SLinus Torvalds 8131af0abbSSukadev Bhattiprolu opts->setuid = 0; 8231af0abbSSukadev Bhattiprolu opts->setgid = 0; 8331af0abbSSukadev Bhattiprolu opts->uid = 0; 8431af0abbSSukadev Bhattiprolu opts->gid = 0; 8531af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 867a673c6bSDomen Puncer 877a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 887a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 897a673c6bSDomen Puncer int token; 907a673c6bSDomen Puncer int option; 917a673c6bSDomen Puncer 927a673c6bSDomen Puncer if (!*p) 931da177e4SLinus Torvalds continue; 947a673c6bSDomen Puncer 957a673c6bSDomen Puncer token = match_token(p, tokens, args); 967a673c6bSDomen Puncer switch (token) { 977a673c6bSDomen Puncer case Opt_uid: 987a673c6bSDomen Puncer if (match_int(&args[0], &option)) 997a673c6bSDomen Puncer return -EINVAL; 10031af0abbSSukadev Bhattiprolu opts->uid = option; 10131af0abbSSukadev Bhattiprolu opts->setuid = 1; 1027a673c6bSDomen Puncer break; 1037a673c6bSDomen Puncer case Opt_gid: 1047a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1057a673c6bSDomen Puncer return -EINVAL; 10631af0abbSSukadev Bhattiprolu opts->gid = option; 10731af0abbSSukadev Bhattiprolu opts->setgid = 1; 1087a673c6bSDomen Puncer break; 1097a673c6bSDomen Puncer case Opt_mode: 1107a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 1117a673c6bSDomen Puncer return -EINVAL; 11231af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 1137a673c6bSDomen Puncer break; 1147a673c6bSDomen Puncer default: 1157a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 1161da177e4SLinus Torvalds return -EINVAL; 1171da177e4SLinus Torvalds } 1181da177e4SLinus Torvalds } 1191da177e4SLinus Torvalds 1201da177e4SLinus Torvalds return 0; 1211da177e4SLinus Torvalds } 1221da177e4SLinus Torvalds 123b87a267eSMiklos Szeredi static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) 124b87a267eSMiklos Szeredi { 12531af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(vfs->mnt_sb); 12631af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 12731af0abbSSukadev Bhattiprolu 12831af0abbSSukadev Bhattiprolu if (opts->setuid) 12931af0abbSSukadev Bhattiprolu seq_printf(seq, ",uid=%u", opts->uid); 13031af0abbSSukadev Bhattiprolu if (opts->setgid) 13131af0abbSSukadev Bhattiprolu seq_printf(seq, ",gid=%u", opts->gid); 13231af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 133b87a267eSMiklos Szeredi 134b87a267eSMiklos Szeredi return 0; 135b87a267eSMiklos Szeredi } 136b87a267eSMiklos Szeredi 137ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 1381da177e4SLinus Torvalds .statfs = simple_statfs, 1391da177e4SLinus Torvalds .remount_fs = devpts_remount, 140b87a267eSMiklos Szeredi .show_options = devpts_show_options, 1411da177e4SLinus Torvalds }; 1421da177e4SLinus Torvalds 143e76b7c01SSukadev Bhattiprolu static void *new_pts_fs_info(void) 144e76b7c01SSukadev Bhattiprolu { 145e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 146e76b7c01SSukadev Bhattiprolu 147e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 148e76b7c01SSukadev Bhattiprolu if (!fsi) 149e76b7c01SSukadev Bhattiprolu return NULL; 150e76b7c01SSukadev Bhattiprolu 151e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 15231af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 153e76b7c01SSukadev Bhattiprolu 154e76b7c01SSukadev Bhattiprolu return fsi; 155e76b7c01SSukadev Bhattiprolu } 156e76b7c01SSukadev Bhattiprolu 1571da177e4SLinus Torvalds static int 1581da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 1591da177e4SLinus Torvalds { 1601da177e4SLinus Torvalds struct inode * inode; 1611da177e4SLinus Torvalds 1621da177e4SLinus Torvalds s->s_blocksize = 1024; 1631da177e4SLinus Torvalds s->s_blocksize_bits = 10; 1641da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 1651da177e4SLinus Torvalds s->s_op = &devpts_sops; 1661da177e4SLinus Torvalds s->s_time_gran = 1; 1671da177e4SLinus Torvalds 168e76b7c01SSukadev Bhattiprolu s->s_fs_info = new_pts_fs_info(); 169e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 170e76b7c01SSukadev Bhattiprolu goto fail; 171e76b7c01SSukadev Bhattiprolu 1721da177e4SLinus Torvalds inode = new_inode(s); 1731da177e4SLinus Torvalds if (!inode) 174e76b7c01SSukadev Bhattiprolu goto free_fsi; 1751da177e4SLinus Torvalds inode->i_ino = 1; 1761da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 1771da177e4SLinus Torvalds inode->i_blocks = 0; 1781da177e4SLinus Torvalds inode->i_uid = inode->i_gid = 0; 1791da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 1801da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 1811da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 1821da177e4SLinus Torvalds inode->i_nlink = 2; 1831da177e4SLinus Torvalds 18459e55e6cSSukadev Bhattiprolu s->s_root = d_alloc_root(inode); 1851da177e4SLinus Torvalds if (s->s_root) 1861da177e4SLinus Torvalds return 0; 1871da177e4SLinus Torvalds 1881da177e4SLinus Torvalds printk("devpts: get root dentry failed\n"); 1891da177e4SLinus Torvalds iput(inode); 190e76b7c01SSukadev Bhattiprolu 191e76b7c01SSukadev Bhattiprolu free_fsi: 192e76b7c01SSukadev Bhattiprolu kfree(s->s_fs_info); 1931da177e4SLinus Torvalds fail: 1941da177e4SLinus Torvalds return -ENOMEM; 1951da177e4SLinus Torvalds } 1961da177e4SLinus Torvalds 197454e2398SDavid Howells static int devpts_get_sb(struct file_system_type *fs_type, 198454e2398SDavid Howells int flags, const char *dev_name, void *data, struct vfsmount *mnt) 1991da177e4SLinus Torvalds { 200454e2398SDavid Howells return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); 2011da177e4SLinus Torvalds } 2021da177e4SLinus Torvalds 203e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 204e76b7c01SSukadev Bhattiprolu { 205e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 206e76b7c01SSukadev Bhattiprolu 207e76b7c01SSukadev Bhattiprolu kfree(fsi); 208e76b7c01SSukadev Bhattiprolu kill_anon_super(sb); 209e76b7c01SSukadev Bhattiprolu } 210e76b7c01SSukadev Bhattiprolu 2111da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 2121da177e4SLinus Torvalds .owner = THIS_MODULE, 2131da177e4SLinus Torvalds .name = "devpts", 2141da177e4SLinus Torvalds .get_sb = devpts_get_sb, 215e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 2161da177e4SLinus Torvalds }; 2171da177e4SLinus Torvalds 2181da177e4SLinus Torvalds /* 2191da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 2201da177e4SLinus Torvalds * to the System V naming convention 2211da177e4SLinus Torvalds */ 2221da177e4SLinus Torvalds 22315f1a633SSukadev Bhattiprolu int devpts_new_index(struct inode *ptmx_inode) 224718a9163SSukadev Bhattiprolu { 225e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 226e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 227718a9163SSukadev Bhattiprolu int index; 2287ee7c12bSAlexey Dobriyan int ida_ret; 229718a9163SSukadev Bhattiprolu 230718a9163SSukadev Bhattiprolu retry: 231e76b7c01SSukadev Bhattiprolu if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) { 232718a9163SSukadev Bhattiprolu return -ENOMEM; 233718a9163SSukadev Bhattiprolu } 234718a9163SSukadev Bhattiprolu 235718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 236e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 2377ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 238718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 2397ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 240718a9163SSukadev Bhattiprolu goto retry; 241718a9163SSukadev Bhattiprolu return -EIO; 242718a9163SSukadev Bhattiprolu } 243718a9163SSukadev Bhattiprolu 244718a9163SSukadev Bhattiprolu if (index >= pty_limit) { 245e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 246718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 247718a9163SSukadev Bhattiprolu return -EIO; 248718a9163SSukadev Bhattiprolu } 249718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 250718a9163SSukadev Bhattiprolu return index; 251718a9163SSukadev Bhattiprolu } 252718a9163SSukadev Bhattiprolu 25315f1a633SSukadev Bhattiprolu void devpts_kill_index(struct inode *ptmx_inode, int idx) 254718a9163SSukadev Bhattiprolu { 255e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 256e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 257e76b7c01SSukadev Bhattiprolu 258718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 259e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 260718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 261718a9163SSukadev Bhattiprolu } 262718a9163SSukadev Bhattiprolu 26315f1a633SSukadev Bhattiprolu int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) 2641da177e4SLinus Torvalds { 265718a9163SSukadev Bhattiprolu int number = tty->index; /* tty layer puts index from devpts_new_index() in here */ 2661da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 2671da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 2681da177e4SLinus Torvalds struct dentry *dentry; 26959e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 27059e55e6cSSukadev Bhattiprolu struct inode *inode = new_inode(sb); 27159e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 27231af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 27331af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 27489a52e10SSukadev Bhattiprolu char s[12]; 2751da177e4SLinus Torvalds 2761da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 2771da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 2781da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 2791da177e4SLinus Torvalds 2801da177e4SLinus Torvalds if (!inode) 2811da177e4SLinus Torvalds return -ENOMEM; 2821da177e4SLinus Torvalds 2831da177e4SLinus Torvalds inode->i_ino = number+2; 284ec4c2aacSDavid Howells inode->i_uid = config.setuid ? config.uid : current_fsuid(); 285ec4c2aacSDavid Howells inode->i_gid = config.setgid ? config.gid : current_fsgid(); 2861da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 28731af0abbSSukadev Bhattiprolu init_special_inode(inode, S_IFCHR|opts->mode, device); 2888e18e294STheodore Ts'o inode->i_private = tty; 289a6f37daaSSukadev Bhattiprolu tty->driver_data = inode; 2901da177e4SLinus Torvalds 29189a52e10SSukadev Bhattiprolu sprintf(s, "%d", number); 29289a52e10SSukadev Bhattiprolu 29359e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 29489a52e10SSukadev Bhattiprolu 29559e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 29689a52e10SSukadev Bhattiprolu if (!IS_ERR(dentry)) { 29789a52e10SSukadev Bhattiprolu d_add(dentry, inode); 29859e55e6cSSukadev Bhattiprolu fsnotify_create(root->d_inode, dentry); 2993972b7f6SFlorin Malita } 3001da177e4SLinus Torvalds 30159e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 3021da177e4SLinus Torvalds 3031da177e4SLinus Torvalds return 0; 3041da177e4SLinus Torvalds } 3051da177e4SLinus Torvalds 30615f1a633SSukadev Bhattiprolu struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) 3071da177e4SLinus Torvalds { 308527b3e47SSukadev Bhattiprolu BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 3091da177e4SLinus Torvalds 310527b3e47SSukadev Bhattiprolu if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 311527b3e47SSukadev Bhattiprolu return (struct tty_struct *)pts_inode->i_private; 312527b3e47SSukadev Bhattiprolu return NULL; 3131da177e4SLinus Torvalds } 3141da177e4SLinus Torvalds 31515f1a633SSukadev Bhattiprolu void devpts_pty_kill(struct tty_struct *tty) 3161da177e4SLinus Torvalds { 317a6f37daaSSukadev Bhattiprolu struct inode *inode = tty->driver_data; 31859e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(inode); 31959e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 320a6f37daaSSukadev Bhattiprolu struct dentry *dentry; 3211da177e4SLinus Torvalds 322a6f37daaSSukadev Bhattiprolu BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 323a6f37daaSSukadev Bhattiprolu 32459e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 325a6f37daaSSukadev Bhattiprolu 326a6f37daaSSukadev Bhattiprolu dentry = d_find_alias(inode); 327a6f37daaSSukadev Bhattiprolu if (dentry && !IS_ERR(dentry)) { 3281da177e4SLinus Torvalds inode->i_nlink--; 3291da177e4SLinus Torvalds d_delete(dentry); 3301da177e4SLinus Torvalds dput(dentry); 3311da177e4SLinus Torvalds } 332a6f37daaSSukadev Bhattiprolu 33359e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 3341da177e4SLinus Torvalds } 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds static int __init init_devpts_fs(void) 3371da177e4SLinus Torvalds { 3381da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 3391da177e4SLinus Torvalds if (!err) { 3401da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 3411da177e4SLinus Torvalds if (IS_ERR(devpts_mnt)) 3421da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 3431da177e4SLinus Torvalds } 3441da177e4SLinus Torvalds return err; 3451da177e4SLinus Torvalds } 3461da177e4SLinus Torvalds 3471da177e4SLinus Torvalds static void __exit exit_devpts_fs(void) 3481da177e4SLinus Torvalds { 3491da177e4SLinus Torvalds unregister_filesystem(&devpts_fs_type); 3501da177e4SLinus Torvalds mntput(devpts_mnt); 3511da177e4SLinus Torvalds } 3521da177e4SLinus Torvalds 3531da177e4SLinus Torvalds module_init(init_devpts_fs) 3541da177e4SLinus Torvalds module_exit(exit_devpts_fs) 3551da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 356