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 301f8f1e29SSukadev Bhattiprolu /* 311f8f1e29SSukadev Bhattiprolu * ptmx is a new node in /dev/pts and will be unused in legacy (single- 321f8f1e29SSukadev Bhattiprolu * instance) mode. To prevent surprises in user space, set permissions of 331f8f1e29SSukadev Bhattiprolu * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful 341f8f1e29SSukadev Bhattiprolu * permissions. 351f8f1e29SSukadev Bhattiprolu */ 361f8f1e29SSukadev Bhattiprolu #define DEVPTS_DEFAULT_PTMX_MODE 0000 37527b3e47SSukadev Bhattiprolu #define PTMX_MINOR 2 38b87a267eSMiklos Szeredi 39718a9163SSukadev Bhattiprolu extern int pty_limit; /* Config limit on Unix98 ptys */ 40718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 41718a9163SSukadev Bhattiprolu 421da177e4SLinus Torvalds static struct vfsmount *devpts_mnt; 431da177e4SLinus Torvalds 4431af0abbSSukadev Bhattiprolu struct pts_mount_opts { 451da177e4SLinus Torvalds int setuid; 461da177e4SLinus Torvalds int setgid; 471da177e4SLinus Torvalds uid_t uid; 481da177e4SLinus Torvalds gid_t gid; 491da177e4SLinus Torvalds umode_t mode; 501f8f1e29SSukadev Bhattiprolu umode_t ptmxmode; 5131af0abbSSukadev Bhattiprolu }; 521da177e4SLinus Torvalds 537a673c6bSDomen Puncer enum { 541f8f1e29SSukadev Bhattiprolu Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, 557a673c6bSDomen Puncer Opt_err 567a673c6bSDomen Puncer }; 577a673c6bSDomen Puncer 58a447c093SSteven Whitehouse static const match_table_t tokens = { 597a673c6bSDomen Puncer {Opt_uid, "uid=%u"}, 607a673c6bSDomen Puncer {Opt_gid, "gid=%u"}, 617a673c6bSDomen Puncer {Opt_mode, "mode=%o"}, 621f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 631f8f1e29SSukadev Bhattiprolu {Opt_ptmxmode, "ptmxmode=%o"}, 641f8f1e29SSukadev Bhattiprolu #endif 657a673c6bSDomen Puncer {Opt_err, NULL} 667a673c6bSDomen Puncer }; 677a673c6bSDomen Puncer 68e76b7c01SSukadev Bhattiprolu struct pts_fs_info { 69e76b7c01SSukadev Bhattiprolu struct ida allocated_ptys; 7031af0abbSSukadev Bhattiprolu struct pts_mount_opts mount_opts; 711f8f1e29SSukadev Bhattiprolu struct dentry *ptmx_dentry; 72e76b7c01SSukadev Bhattiprolu }; 73e76b7c01SSukadev Bhattiprolu 74e76b7c01SSukadev Bhattiprolu static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) 75e76b7c01SSukadev Bhattiprolu { 76e76b7c01SSukadev Bhattiprolu return sb->s_fs_info; 77e76b7c01SSukadev Bhattiprolu } 78e76b7c01SSukadev Bhattiprolu 7959e55e6cSSukadev Bhattiprolu static inline struct super_block *pts_sb_from_inode(struct inode *inode) 8059e55e6cSSukadev Bhattiprolu { 8159e55e6cSSukadev Bhattiprolu if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 8259e55e6cSSukadev Bhattiprolu return inode->i_sb; 8359e55e6cSSukadev Bhattiprolu 8459e55e6cSSukadev Bhattiprolu return devpts_mnt->mnt_sb; 8559e55e6cSSukadev Bhattiprolu } 8659e55e6cSSukadev Bhattiprolu 8753af8ee4SSukadev Bhattiprolu static int parse_mount_options(char *data, struct pts_mount_opts *opts) 881da177e4SLinus Torvalds { 897a673c6bSDomen Puncer char *p; 901da177e4SLinus Torvalds 9131af0abbSSukadev Bhattiprolu opts->setuid = 0; 9231af0abbSSukadev Bhattiprolu opts->setgid = 0; 9331af0abbSSukadev Bhattiprolu opts->uid = 0; 9431af0abbSSukadev Bhattiprolu opts->gid = 0; 9531af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 961f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 977a673c6bSDomen Puncer 987a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 997a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 1007a673c6bSDomen Puncer int token; 1017a673c6bSDomen Puncer int option; 1027a673c6bSDomen Puncer 1037a673c6bSDomen Puncer if (!*p) 1041da177e4SLinus Torvalds continue; 1057a673c6bSDomen Puncer 1067a673c6bSDomen Puncer token = match_token(p, tokens, args); 1077a673c6bSDomen Puncer switch (token) { 1087a673c6bSDomen Puncer case Opt_uid: 1097a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1107a673c6bSDomen Puncer return -EINVAL; 11131af0abbSSukadev Bhattiprolu opts->uid = option; 11231af0abbSSukadev Bhattiprolu opts->setuid = 1; 1137a673c6bSDomen Puncer break; 1147a673c6bSDomen Puncer case Opt_gid: 1157a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1167a673c6bSDomen Puncer return -EINVAL; 11731af0abbSSukadev Bhattiprolu opts->gid = option; 11831af0abbSSukadev Bhattiprolu opts->setgid = 1; 1197a673c6bSDomen Puncer break; 1207a673c6bSDomen Puncer case Opt_mode: 1217a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 1227a673c6bSDomen Puncer return -EINVAL; 12331af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 1247a673c6bSDomen Puncer break; 1251f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1261f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 1271f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 1281f8f1e29SSukadev Bhattiprolu return -EINVAL; 1291f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 1301f8f1e29SSukadev Bhattiprolu break; 1311f8f1e29SSukadev Bhattiprolu #endif 1327a673c6bSDomen Puncer default: 1337a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 1341da177e4SLinus Torvalds return -EINVAL; 1351da177e4SLinus Torvalds } 1361da177e4SLinus Torvalds } 1371da177e4SLinus Torvalds 1381da177e4SLinus Torvalds return 0; 1391da177e4SLinus Torvalds } 1401da177e4SLinus Torvalds 1411f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1421f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 14353af8ee4SSukadev Bhattiprolu { 1441f8f1e29SSukadev Bhattiprolu int mode; 1451f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 1461f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 1471f8f1e29SSukadev Bhattiprolu struct inode *inode; 1481f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 14953af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 15053af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 15153af8ee4SSukadev Bhattiprolu 1521f8f1e29SSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 1531f8f1e29SSukadev Bhattiprolu 1541f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 1551f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 1561f8f1e29SSukadev Bhattiprolu rc = 0; 1571f8f1e29SSukadev Bhattiprolu goto out; 1581f8f1e29SSukadev Bhattiprolu } 1591f8f1e29SSukadev Bhattiprolu 1601f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 1611f8f1e29SSukadev Bhattiprolu if (!dentry) { 1621f8f1e29SSukadev Bhattiprolu printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n"); 1631f8f1e29SSukadev Bhattiprolu goto out; 1641f8f1e29SSukadev Bhattiprolu } 1651f8f1e29SSukadev Bhattiprolu 1661f8f1e29SSukadev Bhattiprolu /* 1671f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 1681f8f1e29SSukadev Bhattiprolu */ 1691f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 1701f8f1e29SSukadev Bhattiprolu if (!inode) { 1711f8f1e29SSukadev Bhattiprolu printk(KERN_ERR "Unable to alloc inode for ptmx node\n"); 1721f8f1e29SSukadev Bhattiprolu dput(dentry); 1731f8f1e29SSukadev Bhattiprolu goto out; 1741f8f1e29SSukadev Bhattiprolu } 1751f8f1e29SSukadev Bhattiprolu 1761f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 1771f8f1e29SSukadev Bhattiprolu inode->i_uid = inode->i_gid = 0; 1781f8f1e29SSukadev Bhattiprolu inode->i_blocks = 0; 1791f8f1e29SSukadev Bhattiprolu inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 1801f8f1e29SSukadev Bhattiprolu 1811f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 1821f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 1831f8f1e29SSukadev Bhattiprolu 1841f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 1851f8f1e29SSukadev Bhattiprolu 1861f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 1871f8f1e29SSukadev Bhattiprolu rc = 0; 1881f8f1e29SSukadev Bhattiprolu 1891f8f1e29SSukadev Bhattiprolu printk(KERN_DEBUG "Created ptmx node in devpts ino %lu\n", 1901f8f1e29SSukadev Bhattiprolu inode->i_ino); 1911f8f1e29SSukadev Bhattiprolu out: 1921f8f1e29SSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 1931f8f1e29SSukadev Bhattiprolu return rc; 1941f8f1e29SSukadev Bhattiprolu } 1951f8f1e29SSukadev Bhattiprolu 1961f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 1971f8f1e29SSukadev Bhattiprolu { 1981f8f1e29SSukadev Bhattiprolu struct inode *inode; 1991f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2001f8f1e29SSukadev Bhattiprolu inode = fsi->ptmx_dentry->d_inode; 2011f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 2021f8f1e29SSukadev Bhattiprolu } 2031f8f1e29SSukadev Bhattiprolu } 2041f8f1e29SSukadev Bhattiprolu #else 2051f8f1e29SSukadev Bhattiprolu static inline void update_ptmx_mode(struct pts_fs_info *fsi) 2061f8f1e29SSukadev Bhattiprolu { 2071f8f1e29SSukadev Bhattiprolu return; 2081f8f1e29SSukadev Bhattiprolu } 2091f8f1e29SSukadev Bhattiprolu #endif 2101f8f1e29SSukadev Bhattiprolu 2111f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 2121f8f1e29SSukadev Bhattiprolu { 2131f8f1e29SSukadev Bhattiprolu int err; 2141f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 2151f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 2161f8f1e29SSukadev Bhattiprolu 2171f8f1e29SSukadev Bhattiprolu err = parse_mount_options(data, opts); 2181f8f1e29SSukadev Bhattiprolu 2191f8f1e29SSukadev Bhattiprolu /* 2201f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 2211f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 2221f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 2231f8f1e29SSukadev Bhattiprolu * so do this even on error return. 2241f8f1e29SSukadev Bhattiprolu */ 2251f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 2261f8f1e29SSukadev Bhattiprolu 2271f8f1e29SSukadev Bhattiprolu return err; 22853af8ee4SSukadev Bhattiprolu } 22953af8ee4SSukadev Bhattiprolu 230b87a267eSMiklos Szeredi static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) 231b87a267eSMiklos Szeredi { 23231af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(vfs->mnt_sb); 23331af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 23431af0abbSSukadev Bhattiprolu 23531af0abbSSukadev Bhattiprolu if (opts->setuid) 23631af0abbSSukadev Bhattiprolu seq_printf(seq, ",uid=%u", opts->uid); 23731af0abbSSukadev Bhattiprolu if (opts->setgid) 23831af0abbSSukadev Bhattiprolu seq_printf(seq, ",gid=%u", opts->gid); 23931af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 2401f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 2411f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 2421f8f1e29SSukadev Bhattiprolu #endif 243b87a267eSMiklos Szeredi 244b87a267eSMiklos Szeredi return 0; 245b87a267eSMiklos Szeredi } 246b87a267eSMiklos Szeredi 247ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 2481da177e4SLinus Torvalds .statfs = simple_statfs, 2491da177e4SLinus Torvalds .remount_fs = devpts_remount, 250b87a267eSMiklos Szeredi .show_options = devpts_show_options, 2511da177e4SLinus Torvalds }; 2521da177e4SLinus Torvalds 253e76b7c01SSukadev Bhattiprolu static void *new_pts_fs_info(void) 254e76b7c01SSukadev Bhattiprolu { 255e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 256e76b7c01SSukadev Bhattiprolu 257e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 258e76b7c01SSukadev Bhattiprolu if (!fsi) 259e76b7c01SSukadev Bhattiprolu return NULL; 260e76b7c01SSukadev Bhattiprolu 261e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 26231af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 2631f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 264e76b7c01SSukadev Bhattiprolu 265e76b7c01SSukadev Bhattiprolu return fsi; 266e76b7c01SSukadev Bhattiprolu } 267e76b7c01SSukadev Bhattiprolu 2681da177e4SLinus Torvalds static int 2691da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 2701da177e4SLinus Torvalds { 2711da177e4SLinus Torvalds struct inode *inode; 2721da177e4SLinus Torvalds 2731da177e4SLinus Torvalds s->s_blocksize = 1024; 2741da177e4SLinus Torvalds s->s_blocksize_bits = 10; 2751da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 2761da177e4SLinus Torvalds s->s_op = &devpts_sops; 2771da177e4SLinus Torvalds s->s_time_gran = 1; 2781da177e4SLinus Torvalds 279e76b7c01SSukadev Bhattiprolu s->s_fs_info = new_pts_fs_info(); 280e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 281e76b7c01SSukadev Bhattiprolu goto fail; 282e76b7c01SSukadev Bhattiprolu 2831da177e4SLinus Torvalds inode = new_inode(s); 2841da177e4SLinus Torvalds if (!inode) 285e76b7c01SSukadev Bhattiprolu goto free_fsi; 2861da177e4SLinus Torvalds inode->i_ino = 1; 2871da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 2881da177e4SLinus Torvalds inode->i_blocks = 0; 2891da177e4SLinus Torvalds inode->i_uid = inode->i_gid = 0; 2901da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 2911da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 2921da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 2931da177e4SLinus Torvalds inode->i_nlink = 2; 2941da177e4SLinus Torvalds 29559e55e6cSSukadev Bhattiprolu s->s_root = d_alloc_root(inode); 2961da177e4SLinus Torvalds if (s->s_root) 2971da177e4SLinus Torvalds return 0; 2981da177e4SLinus Torvalds 2991da177e4SLinus Torvalds printk("devpts: get root dentry failed\n"); 3001da177e4SLinus Torvalds iput(inode); 301e76b7c01SSukadev Bhattiprolu 302e76b7c01SSukadev Bhattiprolu free_fsi: 303e76b7c01SSukadev Bhattiprolu kfree(s->s_fs_info); 3041da177e4SLinus Torvalds fail: 3051da177e4SLinus Torvalds return -ENOMEM; 3061da177e4SLinus Torvalds } 3071da177e4SLinus Torvalds 308d4076ac5SSukadev Bhattiprolu static int compare_init_pts_sb(struct super_block *s, void *p) 309d4076ac5SSukadev Bhattiprolu { 310d4076ac5SSukadev Bhattiprolu if (devpts_mnt) 311d4076ac5SSukadev Bhattiprolu return devpts_mnt->mnt_sb == s; 312d4076ac5SSukadev Bhattiprolu 313d4076ac5SSukadev Bhattiprolu return 0; 314d4076ac5SSukadev Bhattiprolu } 315d4076ac5SSukadev Bhattiprolu 316d4076ac5SSukadev Bhattiprolu /* 317d4076ac5SSukadev Bhattiprolu * get_init_pts_sb() 318d4076ac5SSukadev Bhattiprolu * 319d4076ac5SSukadev Bhattiprolu * This interface is needed to support multiple namespace semantics in 320d4076ac5SSukadev Bhattiprolu * devpts while preserving backward compatibility of the current 'single- 321d4076ac5SSukadev Bhattiprolu * namespace' semantics. i.e all mounts of devpts without the 'newinstance' 322d4076ac5SSukadev Bhattiprolu * mount option should bind to the initial kernel mount, like 323d4076ac5SSukadev Bhattiprolu * get_sb_single(). 324d4076ac5SSukadev Bhattiprolu * 325d4076ac5SSukadev Bhattiprolu * Mounts with 'newinstance' option create a new private namespace. 326d4076ac5SSukadev Bhattiprolu * 327d4076ac5SSukadev Bhattiprolu * But for single-mount semantics, devpts cannot use get_sb_single(), 328d4076ac5SSukadev Bhattiprolu * because get_sb_single()/sget() find and use the super-block from 329d4076ac5SSukadev Bhattiprolu * the most recent mount of devpts. But that recent mount may be a 330d4076ac5SSukadev Bhattiprolu * 'newinstance' mount and get_sb_single() would pick the newinstance 331d4076ac5SSukadev Bhattiprolu * super-block instead of the initial super-block. 332d4076ac5SSukadev Bhattiprolu * 333d4076ac5SSukadev Bhattiprolu * This interface is identical to get_sb_single() except that it 334d4076ac5SSukadev Bhattiprolu * consistently selects the 'single-namespace' superblock even in the 335d4076ac5SSukadev Bhattiprolu * presence of the private namespace (i.e 'newinstance') super-blocks. 336d4076ac5SSukadev Bhattiprolu */ 337d4076ac5SSukadev Bhattiprolu static int get_init_pts_sb(struct file_system_type *fs_type, int flags, 338d4076ac5SSukadev Bhattiprolu void *data, struct vfsmount *mnt) 339d4076ac5SSukadev Bhattiprolu { 340d4076ac5SSukadev Bhattiprolu struct super_block *s; 341d4076ac5SSukadev Bhattiprolu int error; 342d4076ac5SSukadev Bhattiprolu 343d4076ac5SSukadev Bhattiprolu s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); 344d4076ac5SSukadev Bhattiprolu if (IS_ERR(s)) 345d4076ac5SSukadev Bhattiprolu return PTR_ERR(s); 346d4076ac5SSukadev Bhattiprolu 347d4076ac5SSukadev Bhattiprolu if (!s->s_root) { 348d4076ac5SSukadev Bhattiprolu s->s_flags = flags; 349d4076ac5SSukadev Bhattiprolu error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0); 350d4076ac5SSukadev Bhattiprolu if (error) { 351d4076ac5SSukadev Bhattiprolu up_write(&s->s_umount); 352d4076ac5SSukadev Bhattiprolu deactivate_super(s); 353d4076ac5SSukadev Bhattiprolu return error; 354d4076ac5SSukadev Bhattiprolu } 355d4076ac5SSukadev Bhattiprolu s->s_flags |= MS_ACTIVE; 356d4076ac5SSukadev Bhattiprolu } 357d4076ac5SSukadev Bhattiprolu do_remount_sb(s, flags, data, 0); 358d4076ac5SSukadev Bhattiprolu return simple_set_mnt(mnt, s); 359d4076ac5SSukadev Bhattiprolu } 360d4076ac5SSukadev Bhattiprolu 361454e2398SDavid Howells static int devpts_get_sb(struct file_system_type *fs_type, 362454e2398SDavid Howells int flags, const char *dev_name, void *data, struct vfsmount *mnt) 3631da177e4SLinus Torvalds { 364d4076ac5SSukadev Bhattiprolu return get_init_pts_sb(fs_type, flags, data, mnt); 3651da177e4SLinus Torvalds } 3661da177e4SLinus Torvalds 367e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 368e76b7c01SSukadev Bhattiprolu { 369e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 370e76b7c01SSukadev Bhattiprolu 371e76b7c01SSukadev Bhattiprolu kfree(fsi); 3721f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 373e76b7c01SSukadev Bhattiprolu } 374e76b7c01SSukadev Bhattiprolu 3751da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 3761da177e4SLinus Torvalds .owner = THIS_MODULE, 3771da177e4SLinus Torvalds .name = "devpts", 3781da177e4SLinus Torvalds .get_sb = devpts_get_sb, 379e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 3801da177e4SLinus Torvalds }; 3811da177e4SLinus Torvalds 3821da177e4SLinus Torvalds /* 3831da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 3841da177e4SLinus Torvalds * to the System V naming convention 3851da177e4SLinus Torvalds */ 3861da177e4SLinus Torvalds 38715f1a633SSukadev Bhattiprolu int devpts_new_index(struct inode *ptmx_inode) 388718a9163SSukadev Bhattiprolu { 389e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 390e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 391718a9163SSukadev Bhattiprolu int index; 3927ee7c12bSAlexey Dobriyan int ida_ret; 393718a9163SSukadev Bhattiprolu 394718a9163SSukadev Bhattiprolu retry: 395e76b7c01SSukadev Bhattiprolu if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) { 396718a9163SSukadev Bhattiprolu return -ENOMEM; 397718a9163SSukadev Bhattiprolu } 398718a9163SSukadev Bhattiprolu 399718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 400e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 4017ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 402718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 4037ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 404718a9163SSukadev Bhattiprolu goto retry; 405718a9163SSukadev Bhattiprolu return -EIO; 406718a9163SSukadev Bhattiprolu } 407718a9163SSukadev Bhattiprolu 408718a9163SSukadev Bhattiprolu if (index >= pty_limit) { 409e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 410718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 411718a9163SSukadev Bhattiprolu return -EIO; 412718a9163SSukadev Bhattiprolu } 413718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 414718a9163SSukadev Bhattiprolu return index; 415718a9163SSukadev Bhattiprolu } 416718a9163SSukadev Bhattiprolu 41715f1a633SSukadev Bhattiprolu void devpts_kill_index(struct inode *ptmx_inode, int idx) 418718a9163SSukadev Bhattiprolu { 419e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 420e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 421e76b7c01SSukadev Bhattiprolu 422718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 423e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 424718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 425718a9163SSukadev Bhattiprolu } 426718a9163SSukadev Bhattiprolu 42715f1a633SSukadev Bhattiprolu int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) 4281da177e4SLinus Torvalds { 429718a9163SSukadev Bhattiprolu int number = tty->index; /* tty layer puts index from devpts_new_index() in here */ 4301da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 4311da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 4321da177e4SLinus Torvalds struct dentry *dentry; 43359e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 43459e55e6cSSukadev Bhattiprolu struct inode *inode = new_inode(sb); 43559e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 43631af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 43731af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 43889a52e10SSukadev Bhattiprolu char s[12]; 4391da177e4SLinus Torvalds 4401da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 4411da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 4421da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 4431da177e4SLinus Torvalds 4441da177e4SLinus Torvalds if (!inode) 4451da177e4SLinus Torvalds return -ENOMEM; 4461da177e4SLinus Torvalds 4471da177e4SLinus Torvalds inode->i_ino = number+2; 448ec4c2aacSDavid Howells inode->i_uid = config.setuid ? config.uid : current_fsuid(); 449ec4c2aacSDavid Howells inode->i_gid = config.setgid ? config.gid : current_fsgid(); 4501da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 45131af0abbSSukadev Bhattiprolu init_special_inode(inode, S_IFCHR|opts->mode, device); 4528e18e294STheodore Ts'o inode->i_private = tty; 453a6f37daaSSukadev Bhattiprolu tty->driver_data = inode; 4541da177e4SLinus Torvalds 45589a52e10SSukadev Bhattiprolu sprintf(s, "%d", number); 45689a52e10SSukadev Bhattiprolu 45759e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 45889a52e10SSukadev Bhattiprolu 45959e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 46089a52e10SSukadev Bhattiprolu if (!IS_ERR(dentry)) { 46189a52e10SSukadev Bhattiprolu d_add(dentry, inode); 46259e55e6cSSukadev Bhattiprolu fsnotify_create(root->d_inode, dentry); 4633972b7f6SFlorin Malita } 4641da177e4SLinus Torvalds 46559e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 4661da177e4SLinus Torvalds 4671da177e4SLinus Torvalds return 0; 4681da177e4SLinus Torvalds } 4691da177e4SLinus Torvalds 47015f1a633SSukadev Bhattiprolu struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) 4711da177e4SLinus Torvalds { 472527b3e47SSukadev Bhattiprolu BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 4731da177e4SLinus Torvalds 474527b3e47SSukadev Bhattiprolu if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 475527b3e47SSukadev Bhattiprolu return (struct tty_struct *)pts_inode->i_private; 476527b3e47SSukadev Bhattiprolu return NULL; 4771da177e4SLinus Torvalds } 4781da177e4SLinus Torvalds 47915f1a633SSukadev Bhattiprolu void devpts_pty_kill(struct tty_struct *tty) 4801da177e4SLinus Torvalds { 481a6f37daaSSukadev Bhattiprolu struct inode *inode = tty->driver_data; 48259e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(inode); 48359e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 484a6f37daaSSukadev Bhattiprolu struct dentry *dentry; 4851da177e4SLinus Torvalds 486a6f37daaSSukadev Bhattiprolu BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 487a6f37daaSSukadev Bhattiprolu 48859e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 489a6f37daaSSukadev Bhattiprolu 490a6f37daaSSukadev Bhattiprolu dentry = d_find_alias(inode); 491a6f37daaSSukadev Bhattiprolu if (dentry && !IS_ERR(dentry)) { 4921da177e4SLinus Torvalds inode->i_nlink--; 4931da177e4SLinus Torvalds d_delete(dentry); 4941da177e4SLinus Torvalds dput(dentry); 4951da177e4SLinus Torvalds } 496a6f37daaSSukadev Bhattiprolu 49759e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 4981da177e4SLinus Torvalds } 4991da177e4SLinus Torvalds 5001da177e4SLinus Torvalds static int __init init_devpts_fs(void) 5011da177e4SLinus Torvalds { 5021da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 5031da177e4SLinus Torvalds if (!err) { 5041da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 5051da177e4SLinus Torvalds if (IS_ERR(devpts_mnt)) 5061da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 5071da177e4SLinus Torvalds } 5081da177e4SLinus Torvalds return err; 5091da177e4SLinus Torvalds } 5101da177e4SLinus Torvalds 5111da177e4SLinus Torvalds static void __exit exit_devpts_fs(void) 5121da177e4SLinus Torvalds { 5131da177e4SLinus Torvalds unregister_filesystem(&devpts_fs_type); 5141da177e4SLinus Torvalds mntput(devpts_mnt); 5151da177e4SLinus Torvalds } 5161da177e4SLinus Torvalds 5171da177e4SLinus Torvalds module_init(init_devpts_fs) 5181da177e4SLinus Torvalds module_exit(exit_devpts_fs) 5191da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 520