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> 185a0e3ad6STejun Heo #include <linux/slab.h> 191da177e4SLinus Torvalds #include <linux/mount.h> 201da177e4SLinus Torvalds #include <linux/tty.h> 21718a9163SSukadev Bhattiprolu #include <linux/mutex.h> 221fd7317dSNick Black #include <linux/magic.h> 23718a9163SSukadev Bhattiprolu #include <linux/idr.h> 241da177e4SLinus Torvalds #include <linux/devpts_fs.h> 257a673c6bSDomen Puncer #include <linux/parser.h> 263972b7f6SFlorin Malita #include <linux/fsnotify.h> 27b87a267eSMiklos Szeredi #include <linux/seq_file.h> 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 39a4834c10SKonstantin Khlebnikov /* 40a4834c10SKonstantin Khlebnikov * sysctl support for setting limits on the number of Unix98 ptys allocated. 41a4834c10SKonstantin Khlebnikov * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly. 42a4834c10SKonstantin Khlebnikov */ 43a4834c10SKonstantin Khlebnikov static int pty_limit = NR_UNIX98_PTY_DEFAULT; 44a4834c10SKonstantin Khlebnikov static int pty_limit_min; 45a4834c10SKonstantin Khlebnikov static int pty_limit_max = NR_UNIX98_PTY_MAX; 46a4834c10SKonstantin Khlebnikov static int pty_count; 47a4834c10SKonstantin Khlebnikov 48a4834c10SKonstantin Khlebnikov static struct ctl_table pty_table[] = { 49a4834c10SKonstantin Khlebnikov { 50a4834c10SKonstantin Khlebnikov .procname = "max", 51a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 52a4834c10SKonstantin Khlebnikov .mode = 0644, 53a4834c10SKonstantin Khlebnikov .data = &pty_limit, 54a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec_minmax, 55a4834c10SKonstantin Khlebnikov .extra1 = &pty_limit_min, 56a4834c10SKonstantin Khlebnikov .extra2 = &pty_limit_max, 57a4834c10SKonstantin Khlebnikov }, { 58a4834c10SKonstantin Khlebnikov .procname = "nr", 59a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 60a4834c10SKonstantin Khlebnikov .mode = 0444, 61a4834c10SKonstantin Khlebnikov .data = &pty_count, 62a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec, 63a4834c10SKonstantin Khlebnikov }, 64a4834c10SKonstantin Khlebnikov {} 65a4834c10SKonstantin Khlebnikov }; 66a4834c10SKonstantin Khlebnikov 67a4834c10SKonstantin Khlebnikov static struct ctl_table pty_kern_table[] = { 68a4834c10SKonstantin Khlebnikov { 69a4834c10SKonstantin Khlebnikov .procname = "pty", 70a4834c10SKonstantin Khlebnikov .mode = 0555, 71a4834c10SKonstantin Khlebnikov .child = pty_table, 72a4834c10SKonstantin Khlebnikov }, 73a4834c10SKonstantin Khlebnikov {} 74a4834c10SKonstantin Khlebnikov }; 75a4834c10SKonstantin Khlebnikov 76a4834c10SKonstantin Khlebnikov static struct ctl_table pty_root_table[] = { 77a4834c10SKonstantin Khlebnikov { 78a4834c10SKonstantin Khlebnikov .procname = "kernel", 79a4834c10SKonstantin Khlebnikov .mode = 0555, 80a4834c10SKonstantin Khlebnikov .child = pty_kern_table, 81a4834c10SKonstantin Khlebnikov }, 82a4834c10SKonstantin Khlebnikov {} 83a4834c10SKonstantin Khlebnikov }; 84a4834c10SKonstantin Khlebnikov 85718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 86718a9163SSukadev Bhattiprolu 871da177e4SLinus Torvalds static struct vfsmount *devpts_mnt; 881da177e4SLinus Torvalds 8931af0abbSSukadev Bhattiprolu struct pts_mount_opts { 901da177e4SLinus Torvalds int setuid; 911da177e4SLinus Torvalds int setgid; 921da177e4SLinus Torvalds uid_t uid; 931da177e4SLinus Torvalds gid_t gid; 941da177e4SLinus Torvalds umode_t mode; 951f8f1e29SSukadev Bhattiprolu umode_t ptmxmode; 962a1b2dc0SSukadev Bhattiprolu int newinstance; 9731af0abbSSukadev Bhattiprolu }; 981da177e4SLinus Torvalds 997a673c6bSDomen Puncer enum { 1002a1b2dc0SSukadev Bhattiprolu Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, 1017a673c6bSDomen Puncer Opt_err 1027a673c6bSDomen Puncer }; 1037a673c6bSDomen Puncer 104a447c093SSteven Whitehouse static const match_table_t tokens = { 1057a673c6bSDomen Puncer {Opt_uid, "uid=%u"}, 1067a673c6bSDomen Puncer {Opt_gid, "gid=%u"}, 1077a673c6bSDomen Puncer {Opt_mode, "mode=%o"}, 1081f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1091f8f1e29SSukadev Bhattiprolu {Opt_ptmxmode, "ptmxmode=%o"}, 1102a1b2dc0SSukadev Bhattiprolu {Opt_newinstance, "newinstance"}, 1111f8f1e29SSukadev Bhattiprolu #endif 1127a673c6bSDomen Puncer {Opt_err, NULL} 1137a673c6bSDomen Puncer }; 1147a673c6bSDomen Puncer 115e76b7c01SSukadev Bhattiprolu struct pts_fs_info { 116e76b7c01SSukadev Bhattiprolu struct ida allocated_ptys; 11731af0abbSSukadev Bhattiprolu struct pts_mount_opts mount_opts; 1181f8f1e29SSukadev Bhattiprolu struct dentry *ptmx_dentry; 119e76b7c01SSukadev Bhattiprolu }; 120e76b7c01SSukadev Bhattiprolu 121e76b7c01SSukadev Bhattiprolu static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) 122e76b7c01SSukadev Bhattiprolu { 123e76b7c01SSukadev Bhattiprolu return sb->s_fs_info; 124e76b7c01SSukadev Bhattiprolu } 125e76b7c01SSukadev Bhattiprolu 12659e55e6cSSukadev Bhattiprolu static inline struct super_block *pts_sb_from_inode(struct inode *inode) 12759e55e6cSSukadev Bhattiprolu { 1282a1b2dc0SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 12959e55e6cSSukadev Bhattiprolu if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 13059e55e6cSSukadev Bhattiprolu return inode->i_sb; 1312a1b2dc0SSukadev Bhattiprolu #endif 13259e55e6cSSukadev Bhattiprolu return devpts_mnt->mnt_sb; 13359e55e6cSSukadev Bhattiprolu } 13459e55e6cSSukadev Bhattiprolu 1352a1b2dc0SSukadev Bhattiprolu #define PARSE_MOUNT 0 1362a1b2dc0SSukadev Bhattiprolu #define PARSE_REMOUNT 1 1372a1b2dc0SSukadev Bhattiprolu 1381f71ebedSSukadev Bhattiprolu /* 1391f71ebedSSukadev Bhattiprolu * parse_mount_options(): 1401f71ebedSSukadev Bhattiprolu * Set @opts to mount options specified in @data. If an option is not 1411f71ebedSSukadev Bhattiprolu * specified in @data, set it to its default value. The exception is 1421f71ebedSSukadev Bhattiprolu * 'newinstance' option which can only be set/cleared on a mount (i.e. 1431f71ebedSSukadev Bhattiprolu * cannot be changed during remount). 1441f71ebedSSukadev Bhattiprolu * 1451f71ebedSSukadev Bhattiprolu * Note: @data may be NULL (in which case all options are set to default). 1461f71ebedSSukadev Bhattiprolu */ 1472a1b2dc0SSukadev Bhattiprolu static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) 1481da177e4SLinus Torvalds { 1497a673c6bSDomen Puncer char *p; 1501da177e4SLinus Torvalds 15131af0abbSSukadev Bhattiprolu opts->setuid = 0; 15231af0abbSSukadev Bhattiprolu opts->setgid = 0; 15331af0abbSSukadev Bhattiprolu opts->uid = 0; 15431af0abbSSukadev Bhattiprolu opts->gid = 0; 15531af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 1561f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 1577a673c6bSDomen Puncer 1582a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 1592a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 1602a1b2dc0SSukadev Bhattiprolu opts->newinstance = 0; 1612a1b2dc0SSukadev Bhattiprolu 1627a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 1637a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 1647a673c6bSDomen Puncer int token; 1657a673c6bSDomen Puncer int option; 1667a673c6bSDomen Puncer 1677a673c6bSDomen Puncer if (!*p) 1681da177e4SLinus Torvalds continue; 1697a673c6bSDomen Puncer 1707a673c6bSDomen Puncer token = match_token(p, tokens, args); 1717a673c6bSDomen Puncer switch (token) { 1727a673c6bSDomen Puncer case Opt_uid: 1737a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1747a673c6bSDomen Puncer return -EINVAL; 17531af0abbSSukadev Bhattiprolu opts->uid = option; 17631af0abbSSukadev Bhattiprolu opts->setuid = 1; 1777a673c6bSDomen Puncer break; 1787a673c6bSDomen Puncer case Opt_gid: 1797a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1807a673c6bSDomen Puncer return -EINVAL; 18131af0abbSSukadev Bhattiprolu opts->gid = option; 18231af0abbSSukadev Bhattiprolu opts->setgid = 1; 1837a673c6bSDomen Puncer break; 1847a673c6bSDomen Puncer case Opt_mode: 1857a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 1867a673c6bSDomen Puncer return -EINVAL; 18731af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 1887a673c6bSDomen Puncer break; 1891f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1901f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 1911f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 1921f8f1e29SSukadev Bhattiprolu return -EINVAL; 1931f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 1941f8f1e29SSukadev Bhattiprolu break; 1952a1b2dc0SSukadev Bhattiprolu case Opt_newinstance: 1962a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 1972a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 1982a1b2dc0SSukadev Bhattiprolu opts->newinstance = 1; 1992a1b2dc0SSukadev Bhattiprolu break; 2001f8f1e29SSukadev Bhattiprolu #endif 2017a673c6bSDomen Puncer default: 2027a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 2031da177e4SLinus Torvalds return -EINVAL; 2041da177e4SLinus Torvalds } 2051da177e4SLinus Torvalds } 2061da177e4SLinus Torvalds 2071da177e4SLinus Torvalds return 0; 2081da177e4SLinus Torvalds } 2091da177e4SLinus Torvalds 2101f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 2111f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 21253af8ee4SSukadev Bhattiprolu { 2131f8f1e29SSukadev Bhattiprolu int mode; 2141f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 2151f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 2161f8f1e29SSukadev Bhattiprolu struct inode *inode; 2171f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 21853af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 21953af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 22053af8ee4SSukadev Bhattiprolu 2211f8f1e29SSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 2221f8f1e29SSukadev Bhattiprolu 2231f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 2241f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2251f8f1e29SSukadev Bhattiprolu rc = 0; 2261f8f1e29SSukadev Bhattiprolu goto out; 2271f8f1e29SSukadev Bhattiprolu } 2281f8f1e29SSukadev Bhattiprolu 2291f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 2301f8f1e29SSukadev Bhattiprolu if (!dentry) { 2311f8f1e29SSukadev Bhattiprolu printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n"); 2321f8f1e29SSukadev Bhattiprolu goto out; 2331f8f1e29SSukadev Bhattiprolu } 2341f8f1e29SSukadev Bhattiprolu 2351f8f1e29SSukadev Bhattiprolu /* 2361f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 2371f8f1e29SSukadev Bhattiprolu */ 2381f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 2391f8f1e29SSukadev Bhattiprolu if (!inode) { 2401f8f1e29SSukadev Bhattiprolu printk(KERN_ERR "Unable to alloc inode for ptmx node\n"); 2411f8f1e29SSukadev Bhattiprolu dput(dentry); 2421f8f1e29SSukadev Bhattiprolu goto out; 2431f8f1e29SSukadev Bhattiprolu } 2441f8f1e29SSukadev Bhattiprolu 2451f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 2461f8f1e29SSukadev Bhattiprolu inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 2471f8f1e29SSukadev Bhattiprolu 2481f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 2491f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 2501f8f1e29SSukadev Bhattiprolu 2511f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 2521f8f1e29SSukadev Bhattiprolu 2531f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 2541f8f1e29SSukadev Bhattiprolu rc = 0; 2551f8f1e29SSukadev Bhattiprolu out: 2561f8f1e29SSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 2571f8f1e29SSukadev Bhattiprolu return rc; 2581f8f1e29SSukadev Bhattiprolu } 2591f8f1e29SSukadev Bhattiprolu 2601f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 2611f8f1e29SSukadev Bhattiprolu { 2621f8f1e29SSukadev Bhattiprolu struct inode *inode; 2631f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2641f8f1e29SSukadev Bhattiprolu inode = fsi->ptmx_dentry->d_inode; 2651f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 2661f8f1e29SSukadev Bhattiprolu } 2671f8f1e29SSukadev Bhattiprolu } 2681f8f1e29SSukadev Bhattiprolu #else 2691f8f1e29SSukadev Bhattiprolu static inline void update_ptmx_mode(struct pts_fs_info *fsi) 2701f8f1e29SSukadev Bhattiprolu { 2711f8f1e29SSukadev Bhattiprolu return; 2721f8f1e29SSukadev Bhattiprolu } 2731f8f1e29SSukadev Bhattiprolu #endif 2741f8f1e29SSukadev Bhattiprolu 2751f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 2761f8f1e29SSukadev Bhattiprolu { 2771f8f1e29SSukadev Bhattiprolu int err; 2781f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 2791f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 2801f8f1e29SSukadev Bhattiprolu 2812a1b2dc0SSukadev Bhattiprolu err = parse_mount_options(data, PARSE_REMOUNT, opts); 2821f8f1e29SSukadev Bhattiprolu 2831f8f1e29SSukadev Bhattiprolu /* 2841f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 2851f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 2861f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 2871f8f1e29SSukadev Bhattiprolu * so do this even on error return. 2881f8f1e29SSukadev Bhattiprolu */ 2891f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 2901f8f1e29SSukadev Bhattiprolu 2911f8f1e29SSukadev Bhattiprolu return err; 29253af8ee4SSukadev Bhattiprolu } 29353af8ee4SSukadev Bhattiprolu 29434c80b1dSAl Viro static int devpts_show_options(struct seq_file *seq, struct dentry *root) 295b87a267eSMiklos Szeredi { 29634c80b1dSAl Viro struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); 29731af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 29831af0abbSSukadev Bhattiprolu 29931af0abbSSukadev Bhattiprolu if (opts->setuid) 30031af0abbSSukadev Bhattiprolu seq_printf(seq, ",uid=%u", opts->uid); 30131af0abbSSukadev Bhattiprolu if (opts->setgid) 30231af0abbSSukadev Bhattiprolu seq_printf(seq, ",gid=%u", opts->gid); 30331af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 3041f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 3051f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 3061f8f1e29SSukadev Bhattiprolu #endif 307b87a267eSMiklos Szeredi 308b87a267eSMiklos Szeredi return 0; 309b87a267eSMiklos Szeredi } 310b87a267eSMiklos Szeredi 311ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 3121da177e4SLinus Torvalds .statfs = simple_statfs, 3131da177e4SLinus Torvalds .remount_fs = devpts_remount, 314b87a267eSMiklos Szeredi .show_options = devpts_show_options, 3151da177e4SLinus Torvalds }; 3161da177e4SLinus Torvalds 317e76b7c01SSukadev Bhattiprolu static void *new_pts_fs_info(void) 318e76b7c01SSukadev Bhattiprolu { 319e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 320e76b7c01SSukadev Bhattiprolu 321e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 322e76b7c01SSukadev Bhattiprolu if (!fsi) 323e76b7c01SSukadev Bhattiprolu return NULL; 324e76b7c01SSukadev Bhattiprolu 325e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 32631af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 3271f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 328e76b7c01SSukadev Bhattiprolu 329e76b7c01SSukadev Bhattiprolu return fsi; 330e76b7c01SSukadev Bhattiprolu } 331e76b7c01SSukadev Bhattiprolu 3321da177e4SLinus Torvalds static int 3331da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 3341da177e4SLinus Torvalds { 3351da177e4SLinus Torvalds struct inode *inode; 3361da177e4SLinus Torvalds 3371da177e4SLinus Torvalds s->s_blocksize = 1024; 3381da177e4SLinus Torvalds s->s_blocksize_bits = 10; 3391da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 3401da177e4SLinus Torvalds s->s_op = &devpts_sops; 3411da177e4SLinus Torvalds s->s_time_gran = 1; 3421da177e4SLinus Torvalds 343e76b7c01SSukadev Bhattiprolu s->s_fs_info = new_pts_fs_info(); 344e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 345e76b7c01SSukadev Bhattiprolu goto fail; 346e76b7c01SSukadev Bhattiprolu 3471da177e4SLinus Torvalds inode = new_inode(s); 3481da177e4SLinus Torvalds if (!inode) 3493850aba7SAl Viro goto fail; 3501da177e4SLinus Torvalds inode->i_ino = 1; 3511da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 3521da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 3531da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 3541da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 355bfe86848SMiklos Szeredi set_nlink(inode, 2); 3561da177e4SLinus Torvalds 35759e55e6cSSukadev Bhattiprolu s->s_root = d_alloc_root(inode); 3581da177e4SLinus Torvalds if (s->s_root) 3591da177e4SLinus Torvalds return 0; 3601da177e4SLinus Torvalds 361835aa440SAlan Cox printk(KERN_ERR "devpts: get root dentry failed\n"); 3621da177e4SLinus Torvalds iput(inode); 363e76b7c01SSukadev Bhattiprolu 3641da177e4SLinus Torvalds fail: 3651da177e4SLinus Torvalds return -ENOMEM; 3661da177e4SLinus Torvalds } 3671da177e4SLinus Torvalds 3688c056e5bSAndrew Morton #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 369d4076ac5SSukadev Bhattiprolu static int compare_init_pts_sb(struct super_block *s, void *p) 370d4076ac5SSukadev Bhattiprolu { 371d4076ac5SSukadev Bhattiprolu if (devpts_mnt) 372d4076ac5SSukadev Bhattiprolu return devpts_mnt->mnt_sb == s; 3732a1b2dc0SSukadev Bhattiprolu return 0; 3742a1b2dc0SSukadev Bhattiprolu } 3752a1b2dc0SSukadev Bhattiprolu 3762a1b2dc0SSukadev Bhattiprolu /* 377fc14f2feSAl Viro * devpts_mount() 378289f00e2SSukadev Bhattiprolu * 3791bd79035SSukadev Bhattiprolu * If the '-o newinstance' mount option was specified, mount a new 3801bd79035SSukadev Bhattiprolu * (private) instance of devpts. PTYs created in this instance are 3811bd79035SSukadev Bhattiprolu * independent of the PTYs in other devpts instances. 382d4076ac5SSukadev Bhattiprolu * 3831bd79035SSukadev Bhattiprolu * If the '-o newinstance' option was not specified, mount/remount the 3841bd79035SSukadev Bhattiprolu * initial kernel mount of devpts. This type of mount gives the 3851bd79035SSukadev Bhattiprolu * legacy, single-instance semantics. 386d4076ac5SSukadev Bhattiprolu * 3871bd79035SSukadev Bhattiprolu * The 'newinstance' option is needed to support multiple namespace 3881bd79035SSukadev Bhattiprolu * semantics in devpts while preserving backward compatibility of the 3891bd79035SSukadev Bhattiprolu * current 'single-namespace' semantics. i.e all mounts of devpts 3901bd79035SSukadev Bhattiprolu * without the 'newinstance' mount option should bind to the initial 391fc14f2feSAl Viro * kernel mount, like mount_single(). 392d4076ac5SSukadev Bhattiprolu * 3931bd79035SSukadev Bhattiprolu * Mounts with 'newinstance' option create a new, private namespace. 3941bd79035SSukadev Bhattiprolu * 3951bd79035SSukadev Bhattiprolu * NOTE: 3961bd79035SSukadev Bhattiprolu * 397fc14f2feSAl Viro * For single-mount semantics, devpts cannot use mount_single(), 398fc14f2feSAl Viro * because mount_single()/sget() find and use the super-block from 399d4076ac5SSukadev Bhattiprolu * the most recent mount of devpts. But that recent mount may be a 400fc14f2feSAl Viro * 'newinstance' mount and mount_single() would pick the newinstance 401d4076ac5SSukadev Bhattiprolu * super-block instead of the initial super-block. 402d4076ac5SSukadev Bhattiprolu */ 403fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, 404fc14f2feSAl Viro int flags, const char *dev_name, void *data) 4051da177e4SLinus Torvalds { 406482984f0SSukadev Bhattiprolu int error; 407482984f0SSukadev Bhattiprolu struct pts_mount_opts opts; 4081bd79035SSukadev Bhattiprolu struct super_block *s; 4092a1b2dc0SSukadev Bhattiprolu 410482984f0SSukadev Bhattiprolu error = parse_mount_options(data, PARSE_MOUNT, &opts); 411482984f0SSukadev Bhattiprolu if (error) 412fc14f2feSAl Viro return ERR_PTR(error); 413482984f0SSukadev Bhattiprolu 414482984f0SSukadev Bhattiprolu if (opts.newinstance) 4151bd79035SSukadev Bhattiprolu s = sget(fs_type, NULL, set_anon_super, NULL); 416482984f0SSukadev Bhattiprolu else 4171bd79035SSukadev Bhattiprolu s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); 418945cf2c7SSukadev Bhattiprolu 4191bd79035SSukadev Bhattiprolu if (IS_ERR(s)) 420fc14f2feSAl Viro return ERR_CAST(s); 4211bd79035SSukadev Bhattiprolu 4221bd79035SSukadev Bhattiprolu if (!s->s_root) { 4231bd79035SSukadev Bhattiprolu s->s_flags = flags; 4241bd79035SSukadev Bhattiprolu error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0); 425945cf2c7SSukadev Bhattiprolu if (error) 4261bd79035SSukadev Bhattiprolu goto out_undo_sget; 4271bd79035SSukadev Bhattiprolu s->s_flags |= MS_ACTIVE; 4281bd79035SSukadev Bhattiprolu } 429945cf2c7SSukadev Bhattiprolu 4301bd79035SSukadev Bhattiprolu memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts)); 4311bd79035SSukadev Bhattiprolu 4321bd79035SSukadev Bhattiprolu error = mknod_ptmx(s); 433945cf2c7SSukadev Bhattiprolu if (error) 43489468071SAl Viro goto out_undo_sget; 43589468071SAl Viro 436fc14f2feSAl Viro return dget(s->s_root); 437945cf2c7SSukadev Bhattiprolu 4381bd79035SSukadev Bhattiprolu out_undo_sget: 4396f5bbff9SAl Viro deactivate_locked_super(s); 440fc14f2feSAl Viro return ERR_PTR(error); 441482984f0SSukadev Bhattiprolu } 442482984f0SSukadev Bhattiprolu 4432a1b2dc0SSukadev Bhattiprolu #else 4442a1b2dc0SSukadev Bhattiprolu /* 4452a1b2dc0SSukadev Bhattiprolu * This supports only the legacy single-instance semantics (no 4462a1b2dc0SSukadev Bhattiprolu * multiple-instance semantics) 4472a1b2dc0SSukadev Bhattiprolu */ 448fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, int flags, 449fc14f2feSAl Viro const char *dev_name, void *data) 4502a1b2dc0SSukadev Bhattiprolu { 451fc14f2feSAl Viro return mount_single(fs_type, flags, data, devpts_fill_super); 4522a1b2dc0SSukadev Bhattiprolu } 4532a1b2dc0SSukadev Bhattiprolu #endif 4541da177e4SLinus Torvalds 455e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 456e76b7c01SSukadev Bhattiprolu { 457e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 458e76b7c01SSukadev Bhattiprolu 459e76b7c01SSukadev Bhattiprolu kfree(fsi); 4601f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 461e76b7c01SSukadev Bhattiprolu } 462e76b7c01SSukadev Bhattiprolu 4631da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 4641da177e4SLinus Torvalds .name = "devpts", 465fc14f2feSAl Viro .mount = devpts_mount, 466e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 4671da177e4SLinus Torvalds }; 4681da177e4SLinus Torvalds 4691da177e4SLinus Torvalds /* 4701da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 4711da177e4SLinus Torvalds * to the System V naming convention 4721da177e4SLinus Torvalds */ 4731da177e4SLinus Torvalds 47415f1a633SSukadev Bhattiprolu int devpts_new_index(struct inode *ptmx_inode) 475718a9163SSukadev Bhattiprolu { 476e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 477e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 478718a9163SSukadev Bhattiprolu int index; 4797ee7c12bSAlexey Dobriyan int ida_ret; 480718a9163SSukadev Bhattiprolu 481718a9163SSukadev Bhattiprolu retry: 482835aa440SAlan Cox if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) 483718a9163SSukadev Bhattiprolu return -ENOMEM; 484718a9163SSukadev Bhattiprolu 485718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 486e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 4877ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 488718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 4897ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 490718a9163SSukadev Bhattiprolu goto retry; 491718a9163SSukadev Bhattiprolu return -EIO; 492718a9163SSukadev Bhattiprolu } 493718a9163SSukadev Bhattiprolu 494718a9163SSukadev Bhattiprolu if (index >= pty_limit) { 495e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 496718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 497718a9163SSukadev Bhattiprolu return -EIO; 498718a9163SSukadev Bhattiprolu } 499a4834c10SKonstantin Khlebnikov pty_count++; 500718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 501718a9163SSukadev Bhattiprolu return index; 502718a9163SSukadev Bhattiprolu } 503718a9163SSukadev Bhattiprolu 50415f1a633SSukadev Bhattiprolu void devpts_kill_index(struct inode *ptmx_inode, int idx) 505718a9163SSukadev Bhattiprolu { 506e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 507e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 508e76b7c01SSukadev Bhattiprolu 509718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 510e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 511a4834c10SKonstantin Khlebnikov pty_count--; 512718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 513718a9163SSukadev Bhattiprolu } 514718a9163SSukadev Bhattiprolu 51515f1a633SSukadev Bhattiprolu int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) 5161da177e4SLinus Torvalds { 517835aa440SAlan Cox /* tty layer puts index from devpts_new_index() in here */ 518835aa440SAlan Cox int number = tty->index; 5191da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 5201da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 5211da177e4SLinus Torvalds struct dentry *dentry; 52259e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 52359e55e6cSSukadev Bhattiprolu struct inode *inode = new_inode(sb); 52459e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 52531af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 52631af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 527aa597bc1SAndrey Vagin int ret = 0; 52889a52e10SSukadev Bhattiprolu char s[12]; 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 5311da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 5321da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 5331da177e4SLinus Torvalds 5341da177e4SLinus Torvalds if (!inode) 5351da177e4SLinus Torvalds return -ENOMEM; 5361da177e4SLinus Torvalds 537d0eafc7dSDavid Howells inode->i_ino = number + 3; 538d0eafc7dSDavid Howells inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); 539d0eafc7dSDavid Howells inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); 5401da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 54131af0abbSSukadev Bhattiprolu init_special_inode(inode, S_IFCHR|opts->mode, device); 5428e18e294STheodore Ts'o inode->i_private = tty; 543a6f37daaSSukadev Bhattiprolu tty->driver_data = inode; 5441da177e4SLinus Torvalds 54589a52e10SSukadev Bhattiprolu sprintf(s, "%d", number); 54689a52e10SSukadev Bhattiprolu 54759e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 54889a52e10SSukadev Bhattiprolu 54959e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 550b12d1259SAndrey Vagin if (dentry) { 55189a52e10SSukadev Bhattiprolu d_add(dentry, inode); 55259e55e6cSSukadev Bhattiprolu fsnotify_create(root->d_inode, dentry); 553aa597bc1SAndrey Vagin } else { 554aa597bc1SAndrey Vagin iput(inode); 555aa597bc1SAndrey Vagin ret = -ENOMEM; 5563972b7f6SFlorin Malita } 5571da177e4SLinus Torvalds 55859e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 5591da177e4SLinus Torvalds 560aa597bc1SAndrey Vagin return ret; 5611da177e4SLinus Torvalds } 5621da177e4SLinus Torvalds 56315f1a633SSukadev Bhattiprolu struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) 5641da177e4SLinus Torvalds { 565edfacdd6SSukadev Bhattiprolu struct dentry *dentry; 566edfacdd6SSukadev Bhattiprolu struct tty_struct *tty; 567edfacdd6SSukadev Bhattiprolu 568527b3e47SSukadev Bhattiprolu BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 5691da177e4SLinus Torvalds 570edfacdd6SSukadev Bhattiprolu /* Ensure dentry has not been deleted by devpts_pty_kill() */ 571edfacdd6SSukadev Bhattiprolu dentry = d_find_alias(pts_inode); 572edfacdd6SSukadev Bhattiprolu if (!dentry) 573527b3e47SSukadev Bhattiprolu return NULL; 574edfacdd6SSukadev Bhattiprolu 575edfacdd6SSukadev Bhattiprolu tty = NULL; 576edfacdd6SSukadev Bhattiprolu if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 577edfacdd6SSukadev Bhattiprolu tty = (struct tty_struct *)pts_inode->i_private; 578edfacdd6SSukadev Bhattiprolu 579edfacdd6SSukadev Bhattiprolu dput(dentry); 580edfacdd6SSukadev Bhattiprolu 581edfacdd6SSukadev Bhattiprolu return tty; 5821da177e4SLinus Torvalds } 5831da177e4SLinus Torvalds 58415f1a633SSukadev Bhattiprolu void devpts_pty_kill(struct tty_struct *tty) 5851da177e4SLinus Torvalds { 586a6f37daaSSukadev Bhattiprolu struct inode *inode = tty->driver_data; 58759e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(inode); 58859e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 589a6f37daaSSukadev Bhattiprolu struct dentry *dentry; 5901da177e4SLinus Torvalds 591a6f37daaSSukadev Bhattiprolu BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 592a6f37daaSSukadev Bhattiprolu 59359e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 594a6f37daaSSukadev Bhattiprolu 595a6f37daaSSukadev Bhattiprolu dentry = d_find_alias(inode); 5962a1b2dc0SSukadev Bhattiprolu 5976d6b77f1SMiklos Szeredi drop_nlink(inode); 5981da177e4SLinus Torvalds d_delete(dentry); 599835aa440SAlan Cox dput(dentry); /* d_alloc_name() in devpts_pty_new() */ 600835aa440SAlan Cox dput(dentry); /* d_find_alias above */ 601aa597bc1SAndrey Vagin 60259e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 6031da177e4SLinus Torvalds } 6041da177e4SLinus Torvalds 6051da177e4SLinus Torvalds static int __init init_devpts_fs(void) 6061da177e4SLinus Torvalds { 6071da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 608a4834c10SKonstantin Khlebnikov struct ctl_table_header *table; 609a4834c10SKonstantin Khlebnikov 6101da177e4SLinus Torvalds if (!err) { 611a4834c10SKonstantin Khlebnikov table = register_sysctl_table(pty_root_table); 6121da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 61393d5581eSAlan Cox if (IS_ERR(devpts_mnt)) { 6141da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 61593d5581eSAlan Cox unregister_filesystem(&devpts_fs_type); 616a4834c10SKonstantin Khlebnikov unregister_sysctl_table(table); 61793d5581eSAlan Cox } 6181da177e4SLinus Torvalds } 6191da177e4SLinus Torvalds return err; 6201da177e4SLinus Torvalds } 6211da177e4SLinus Torvalds module_init(init_devpts_fs) 622