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; 44e9aba515SKonstantin Khlebnikov static int pty_reserve = NR_UNIX98_PTY_RESERVE; 45a4834c10SKonstantin Khlebnikov static int pty_limit_min; 46e9aba515SKonstantin Khlebnikov static int pty_limit_max = INT_MAX; 47a4834c10SKonstantin Khlebnikov static int pty_count; 48a4834c10SKonstantin Khlebnikov 49a4834c10SKonstantin Khlebnikov static struct ctl_table pty_table[] = { 50a4834c10SKonstantin Khlebnikov { 51a4834c10SKonstantin Khlebnikov .procname = "max", 52a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 53a4834c10SKonstantin Khlebnikov .mode = 0644, 54a4834c10SKonstantin Khlebnikov .data = &pty_limit, 55a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec_minmax, 56a4834c10SKonstantin Khlebnikov .extra1 = &pty_limit_min, 57a4834c10SKonstantin Khlebnikov .extra2 = &pty_limit_max, 58a4834c10SKonstantin Khlebnikov }, { 59e9aba515SKonstantin Khlebnikov .procname = "reserve", 60e9aba515SKonstantin Khlebnikov .maxlen = sizeof(int), 61e9aba515SKonstantin Khlebnikov .mode = 0644, 62e9aba515SKonstantin Khlebnikov .data = &pty_reserve, 63e9aba515SKonstantin Khlebnikov .proc_handler = proc_dointvec_minmax, 64e9aba515SKonstantin Khlebnikov .extra1 = &pty_limit_min, 65e9aba515SKonstantin Khlebnikov .extra2 = &pty_limit_max, 66e9aba515SKonstantin Khlebnikov }, { 67a4834c10SKonstantin Khlebnikov .procname = "nr", 68a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 69a4834c10SKonstantin Khlebnikov .mode = 0444, 70a4834c10SKonstantin Khlebnikov .data = &pty_count, 71a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec, 72a4834c10SKonstantin Khlebnikov }, 73a4834c10SKonstantin Khlebnikov {} 74a4834c10SKonstantin Khlebnikov }; 75a4834c10SKonstantin Khlebnikov 76a4834c10SKonstantin Khlebnikov static struct ctl_table pty_kern_table[] = { 77a4834c10SKonstantin Khlebnikov { 78a4834c10SKonstantin Khlebnikov .procname = "pty", 79a4834c10SKonstantin Khlebnikov .mode = 0555, 80a4834c10SKonstantin Khlebnikov .child = pty_table, 81a4834c10SKonstantin Khlebnikov }, 82a4834c10SKonstantin Khlebnikov {} 83a4834c10SKonstantin Khlebnikov }; 84a4834c10SKonstantin Khlebnikov 85a4834c10SKonstantin Khlebnikov static struct ctl_table pty_root_table[] = { 86a4834c10SKonstantin Khlebnikov { 87a4834c10SKonstantin Khlebnikov .procname = "kernel", 88a4834c10SKonstantin Khlebnikov .mode = 0555, 89a4834c10SKonstantin Khlebnikov .child = pty_kern_table, 90a4834c10SKonstantin Khlebnikov }, 91a4834c10SKonstantin Khlebnikov {} 92a4834c10SKonstantin Khlebnikov }; 93a4834c10SKonstantin Khlebnikov 94718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 95718a9163SSukadev Bhattiprolu 961da177e4SLinus Torvalds static struct vfsmount *devpts_mnt; 971da177e4SLinus Torvalds 9831af0abbSSukadev Bhattiprolu struct pts_mount_opts { 991da177e4SLinus Torvalds int setuid; 1001da177e4SLinus Torvalds int setgid; 1011da177e4SLinus Torvalds uid_t uid; 1021da177e4SLinus Torvalds gid_t gid; 1031da177e4SLinus Torvalds umode_t mode; 1041f8f1e29SSukadev Bhattiprolu umode_t ptmxmode; 1052a1b2dc0SSukadev Bhattiprolu int newinstance; 106e9aba515SKonstantin Khlebnikov int max; 10731af0abbSSukadev Bhattiprolu }; 1081da177e4SLinus Torvalds 1097a673c6bSDomen Puncer enum { 110e9aba515SKonstantin Khlebnikov Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max, 1117a673c6bSDomen Puncer Opt_err 1127a673c6bSDomen Puncer }; 1137a673c6bSDomen Puncer 114a447c093SSteven Whitehouse static const match_table_t tokens = { 1157a673c6bSDomen Puncer {Opt_uid, "uid=%u"}, 1167a673c6bSDomen Puncer {Opt_gid, "gid=%u"}, 1177a673c6bSDomen Puncer {Opt_mode, "mode=%o"}, 1181f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1191f8f1e29SSukadev Bhattiprolu {Opt_ptmxmode, "ptmxmode=%o"}, 1202a1b2dc0SSukadev Bhattiprolu {Opt_newinstance, "newinstance"}, 121e9aba515SKonstantin Khlebnikov {Opt_max, "max=%d"}, 1221f8f1e29SSukadev Bhattiprolu #endif 1237a673c6bSDomen Puncer {Opt_err, NULL} 1247a673c6bSDomen Puncer }; 1257a673c6bSDomen Puncer 126e76b7c01SSukadev Bhattiprolu struct pts_fs_info { 127e76b7c01SSukadev Bhattiprolu struct ida allocated_ptys; 12831af0abbSSukadev Bhattiprolu struct pts_mount_opts mount_opts; 1291f8f1e29SSukadev Bhattiprolu struct dentry *ptmx_dentry; 130e76b7c01SSukadev Bhattiprolu }; 131e76b7c01SSukadev Bhattiprolu 132e76b7c01SSukadev Bhattiprolu static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) 133e76b7c01SSukadev Bhattiprolu { 134e76b7c01SSukadev Bhattiprolu return sb->s_fs_info; 135e76b7c01SSukadev Bhattiprolu } 136e76b7c01SSukadev Bhattiprolu 13759e55e6cSSukadev Bhattiprolu static inline struct super_block *pts_sb_from_inode(struct inode *inode) 13859e55e6cSSukadev Bhattiprolu { 1392a1b2dc0SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 14059e55e6cSSukadev Bhattiprolu if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 14159e55e6cSSukadev Bhattiprolu return inode->i_sb; 1422a1b2dc0SSukadev Bhattiprolu #endif 14359e55e6cSSukadev Bhattiprolu return devpts_mnt->mnt_sb; 14459e55e6cSSukadev Bhattiprolu } 14559e55e6cSSukadev Bhattiprolu 1462a1b2dc0SSukadev Bhattiprolu #define PARSE_MOUNT 0 1472a1b2dc0SSukadev Bhattiprolu #define PARSE_REMOUNT 1 1482a1b2dc0SSukadev Bhattiprolu 1491f71ebedSSukadev Bhattiprolu /* 1501f71ebedSSukadev Bhattiprolu * parse_mount_options(): 1511f71ebedSSukadev Bhattiprolu * Set @opts to mount options specified in @data. If an option is not 1521f71ebedSSukadev Bhattiprolu * specified in @data, set it to its default value. The exception is 1531f71ebedSSukadev Bhattiprolu * 'newinstance' option which can only be set/cleared on a mount (i.e. 1541f71ebedSSukadev Bhattiprolu * cannot be changed during remount). 1551f71ebedSSukadev Bhattiprolu * 1561f71ebedSSukadev Bhattiprolu * Note: @data may be NULL (in which case all options are set to default). 1571f71ebedSSukadev Bhattiprolu */ 1582a1b2dc0SSukadev Bhattiprolu static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) 1591da177e4SLinus Torvalds { 1607a673c6bSDomen Puncer char *p; 1611da177e4SLinus Torvalds 16231af0abbSSukadev Bhattiprolu opts->setuid = 0; 16331af0abbSSukadev Bhattiprolu opts->setgid = 0; 16431af0abbSSukadev Bhattiprolu opts->uid = 0; 16531af0abbSSukadev Bhattiprolu opts->gid = 0; 16631af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 1671f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 168e9aba515SKonstantin Khlebnikov opts->max = NR_UNIX98_PTY_MAX; 1697a673c6bSDomen Puncer 1702a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 1712a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 1722a1b2dc0SSukadev Bhattiprolu opts->newinstance = 0; 1732a1b2dc0SSukadev Bhattiprolu 1747a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 1757a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 1767a673c6bSDomen Puncer int token; 1777a673c6bSDomen Puncer int option; 1787a673c6bSDomen Puncer 1797a673c6bSDomen Puncer if (!*p) 1801da177e4SLinus Torvalds continue; 1817a673c6bSDomen Puncer 1827a673c6bSDomen Puncer token = match_token(p, tokens, args); 1837a673c6bSDomen Puncer switch (token) { 1847a673c6bSDomen Puncer case Opt_uid: 1857a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1867a673c6bSDomen Puncer return -EINVAL; 18731af0abbSSukadev Bhattiprolu opts->uid = option; 18831af0abbSSukadev Bhattiprolu opts->setuid = 1; 1897a673c6bSDomen Puncer break; 1907a673c6bSDomen Puncer case Opt_gid: 1917a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1927a673c6bSDomen Puncer return -EINVAL; 19331af0abbSSukadev Bhattiprolu opts->gid = option; 19431af0abbSSukadev Bhattiprolu opts->setgid = 1; 1957a673c6bSDomen Puncer break; 1967a673c6bSDomen Puncer case Opt_mode: 1977a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 1987a673c6bSDomen Puncer return -EINVAL; 19931af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 2007a673c6bSDomen Puncer break; 2011f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 2021f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 2031f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 2041f8f1e29SSukadev Bhattiprolu return -EINVAL; 2051f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 2061f8f1e29SSukadev Bhattiprolu break; 2072a1b2dc0SSukadev Bhattiprolu case Opt_newinstance: 2082a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 2092a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 2102a1b2dc0SSukadev Bhattiprolu opts->newinstance = 1; 2112a1b2dc0SSukadev Bhattiprolu break; 212e9aba515SKonstantin Khlebnikov case Opt_max: 213e9aba515SKonstantin Khlebnikov if (match_int(&args[0], &option) || 214e9aba515SKonstantin Khlebnikov option < 0 || option > NR_UNIX98_PTY_MAX) 215e9aba515SKonstantin Khlebnikov return -EINVAL; 216e9aba515SKonstantin Khlebnikov opts->max = option; 217e9aba515SKonstantin Khlebnikov break; 2181f8f1e29SSukadev Bhattiprolu #endif 2197a673c6bSDomen Puncer default: 2207a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 2211da177e4SLinus Torvalds return -EINVAL; 2221da177e4SLinus Torvalds } 2231da177e4SLinus Torvalds } 2241da177e4SLinus Torvalds 2251da177e4SLinus Torvalds return 0; 2261da177e4SLinus Torvalds } 2271da177e4SLinus Torvalds 2281f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 2291f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 23053af8ee4SSukadev Bhattiprolu { 2311f8f1e29SSukadev Bhattiprolu int mode; 2321f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 2331f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 2341f8f1e29SSukadev Bhattiprolu struct inode *inode; 2351f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 23653af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 23753af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 23853af8ee4SSukadev Bhattiprolu 2391f8f1e29SSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 2401f8f1e29SSukadev Bhattiprolu 2411f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 2421f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2431f8f1e29SSukadev Bhattiprolu rc = 0; 2441f8f1e29SSukadev Bhattiprolu goto out; 2451f8f1e29SSukadev Bhattiprolu } 2461f8f1e29SSukadev Bhattiprolu 2471f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 2481f8f1e29SSukadev Bhattiprolu if (!dentry) { 2491f8f1e29SSukadev Bhattiprolu printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n"); 2501f8f1e29SSukadev Bhattiprolu goto out; 2511f8f1e29SSukadev Bhattiprolu } 2521f8f1e29SSukadev Bhattiprolu 2531f8f1e29SSukadev Bhattiprolu /* 2541f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 2551f8f1e29SSukadev Bhattiprolu */ 2561f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 2571f8f1e29SSukadev Bhattiprolu if (!inode) { 2581f8f1e29SSukadev Bhattiprolu printk(KERN_ERR "Unable to alloc inode for ptmx node\n"); 2591f8f1e29SSukadev Bhattiprolu dput(dentry); 2601f8f1e29SSukadev Bhattiprolu goto out; 2611f8f1e29SSukadev Bhattiprolu } 2621f8f1e29SSukadev Bhattiprolu 2631f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 2641f8f1e29SSukadev Bhattiprolu inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 2651f8f1e29SSukadev Bhattiprolu 2661f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 2671f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 2681f8f1e29SSukadev Bhattiprolu 2691f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 2701f8f1e29SSukadev Bhattiprolu 2711f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 2721f8f1e29SSukadev Bhattiprolu rc = 0; 2731f8f1e29SSukadev Bhattiprolu out: 2741f8f1e29SSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 2751f8f1e29SSukadev Bhattiprolu return rc; 2761f8f1e29SSukadev Bhattiprolu } 2771f8f1e29SSukadev Bhattiprolu 2781f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 2791f8f1e29SSukadev Bhattiprolu { 2801f8f1e29SSukadev Bhattiprolu struct inode *inode; 2811f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2821f8f1e29SSukadev Bhattiprolu inode = fsi->ptmx_dentry->d_inode; 2831f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 2841f8f1e29SSukadev Bhattiprolu } 2851f8f1e29SSukadev Bhattiprolu } 2861f8f1e29SSukadev Bhattiprolu #else 2871f8f1e29SSukadev Bhattiprolu static inline void update_ptmx_mode(struct pts_fs_info *fsi) 2881f8f1e29SSukadev Bhattiprolu { 2891f8f1e29SSukadev Bhattiprolu return; 2901f8f1e29SSukadev Bhattiprolu } 2911f8f1e29SSukadev Bhattiprolu #endif 2921f8f1e29SSukadev Bhattiprolu 2931f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 2941f8f1e29SSukadev Bhattiprolu { 2951f8f1e29SSukadev Bhattiprolu int err; 2961f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 2971f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 2981f8f1e29SSukadev Bhattiprolu 2992a1b2dc0SSukadev Bhattiprolu err = parse_mount_options(data, PARSE_REMOUNT, opts); 3001f8f1e29SSukadev Bhattiprolu 3011f8f1e29SSukadev Bhattiprolu /* 3021f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 3031f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 3041f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 3051f8f1e29SSukadev Bhattiprolu * so do this even on error return. 3061f8f1e29SSukadev Bhattiprolu */ 3071f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 3081f8f1e29SSukadev Bhattiprolu 3091f8f1e29SSukadev Bhattiprolu return err; 31053af8ee4SSukadev Bhattiprolu } 31153af8ee4SSukadev Bhattiprolu 31234c80b1dSAl Viro static int devpts_show_options(struct seq_file *seq, struct dentry *root) 313b87a267eSMiklos Szeredi { 31434c80b1dSAl Viro struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); 31531af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 31631af0abbSSukadev Bhattiprolu 31731af0abbSSukadev Bhattiprolu if (opts->setuid) 31831af0abbSSukadev Bhattiprolu seq_printf(seq, ",uid=%u", opts->uid); 31931af0abbSSukadev Bhattiprolu if (opts->setgid) 32031af0abbSSukadev Bhattiprolu seq_printf(seq, ",gid=%u", opts->gid); 32131af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 3221f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 3231f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 324e9aba515SKonstantin Khlebnikov if (opts->max < NR_UNIX98_PTY_MAX) 325e9aba515SKonstantin Khlebnikov seq_printf(seq, ",max=%d", opts->max); 3261f8f1e29SSukadev Bhattiprolu #endif 327b87a267eSMiklos Szeredi 328b87a267eSMiklos Szeredi return 0; 329b87a267eSMiklos Szeredi } 330b87a267eSMiklos Szeredi 331ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 3321da177e4SLinus Torvalds .statfs = simple_statfs, 3331da177e4SLinus Torvalds .remount_fs = devpts_remount, 334b87a267eSMiklos Szeredi .show_options = devpts_show_options, 3351da177e4SLinus Torvalds }; 3361da177e4SLinus Torvalds 337e76b7c01SSukadev Bhattiprolu static void *new_pts_fs_info(void) 338e76b7c01SSukadev Bhattiprolu { 339e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 340e76b7c01SSukadev Bhattiprolu 341e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 342e76b7c01SSukadev Bhattiprolu if (!fsi) 343e76b7c01SSukadev Bhattiprolu return NULL; 344e76b7c01SSukadev Bhattiprolu 345e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 34631af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 3471f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 348e76b7c01SSukadev Bhattiprolu 349e76b7c01SSukadev Bhattiprolu return fsi; 350e76b7c01SSukadev Bhattiprolu } 351e76b7c01SSukadev Bhattiprolu 3521da177e4SLinus Torvalds static int 3531da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 3541da177e4SLinus Torvalds { 3551da177e4SLinus Torvalds struct inode *inode; 3561da177e4SLinus Torvalds 3571da177e4SLinus Torvalds s->s_blocksize = 1024; 3581da177e4SLinus Torvalds s->s_blocksize_bits = 10; 3591da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 3601da177e4SLinus Torvalds s->s_op = &devpts_sops; 3611da177e4SLinus Torvalds s->s_time_gran = 1; 3621da177e4SLinus Torvalds 363e76b7c01SSukadev Bhattiprolu s->s_fs_info = new_pts_fs_info(); 364e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 365e76b7c01SSukadev Bhattiprolu goto fail; 366e76b7c01SSukadev Bhattiprolu 3671da177e4SLinus Torvalds inode = new_inode(s); 3681da177e4SLinus Torvalds if (!inode) 3693850aba7SAl Viro goto fail; 3701da177e4SLinus Torvalds inode->i_ino = 1; 3711da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 3721da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 3731da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 3741da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 375bfe86848SMiklos Szeredi set_nlink(inode, 2); 3761da177e4SLinus Torvalds 37759e55e6cSSukadev Bhattiprolu s->s_root = d_alloc_root(inode); 3781da177e4SLinus Torvalds if (s->s_root) 3791da177e4SLinus Torvalds return 0; 3801da177e4SLinus Torvalds 381835aa440SAlan Cox printk(KERN_ERR "devpts: get root dentry failed\n"); 3821da177e4SLinus Torvalds iput(inode); 383e76b7c01SSukadev Bhattiprolu 3841da177e4SLinus Torvalds fail: 3851da177e4SLinus Torvalds return -ENOMEM; 3861da177e4SLinus Torvalds } 3871da177e4SLinus Torvalds 3888c056e5bSAndrew Morton #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 389d4076ac5SSukadev Bhattiprolu static int compare_init_pts_sb(struct super_block *s, void *p) 390d4076ac5SSukadev Bhattiprolu { 391d4076ac5SSukadev Bhattiprolu if (devpts_mnt) 392d4076ac5SSukadev Bhattiprolu return devpts_mnt->mnt_sb == s; 3932a1b2dc0SSukadev Bhattiprolu return 0; 3942a1b2dc0SSukadev Bhattiprolu } 3952a1b2dc0SSukadev Bhattiprolu 3962a1b2dc0SSukadev Bhattiprolu /* 397fc14f2feSAl Viro * devpts_mount() 398289f00e2SSukadev Bhattiprolu * 3991bd79035SSukadev Bhattiprolu * If the '-o newinstance' mount option was specified, mount a new 4001bd79035SSukadev Bhattiprolu * (private) instance of devpts. PTYs created in this instance are 4011bd79035SSukadev Bhattiprolu * independent of the PTYs in other devpts instances. 402d4076ac5SSukadev Bhattiprolu * 4031bd79035SSukadev Bhattiprolu * If the '-o newinstance' option was not specified, mount/remount the 4041bd79035SSukadev Bhattiprolu * initial kernel mount of devpts. This type of mount gives the 4051bd79035SSukadev Bhattiprolu * legacy, single-instance semantics. 406d4076ac5SSukadev Bhattiprolu * 4071bd79035SSukadev Bhattiprolu * The 'newinstance' option is needed to support multiple namespace 4081bd79035SSukadev Bhattiprolu * semantics in devpts while preserving backward compatibility of the 4091bd79035SSukadev Bhattiprolu * current 'single-namespace' semantics. i.e all mounts of devpts 4101bd79035SSukadev Bhattiprolu * without the 'newinstance' mount option should bind to the initial 411fc14f2feSAl Viro * kernel mount, like mount_single(). 412d4076ac5SSukadev Bhattiprolu * 4131bd79035SSukadev Bhattiprolu * Mounts with 'newinstance' option create a new, private namespace. 4141bd79035SSukadev Bhattiprolu * 4151bd79035SSukadev Bhattiprolu * NOTE: 4161bd79035SSukadev Bhattiprolu * 417fc14f2feSAl Viro * For single-mount semantics, devpts cannot use mount_single(), 418fc14f2feSAl Viro * because mount_single()/sget() find and use the super-block from 419d4076ac5SSukadev Bhattiprolu * the most recent mount of devpts. But that recent mount may be a 420fc14f2feSAl Viro * 'newinstance' mount and mount_single() would pick the newinstance 421d4076ac5SSukadev Bhattiprolu * super-block instead of the initial super-block. 422d4076ac5SSukadev Bhattiprolu */ 423fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, 424fc14f2feSAl Viro int flags, const char *dev_name, void *data) 4251da177e4SLinus Torvalds { 426482984f0SSukadev Bhattiprolu int error; 427482984f0SSukadev Bhattiprolu struct pts_mount_opts opts; 4281bd79035SSukadev Bhattiprolu struct super_block *s; 4292a1b2dc0SSukadev Bhattiprolu 430482984f0SSukadev Bhattiprolu error = parse_mount_options(data, PARSE_MOUNT, &opts); 431482984f0SSukadev Bhattiprolu if (error) 432fc14f2feSAl Viro return ERR_PTR(error); 433482984f0SSukadev Bhattiprolu 434482984f0SSukadev Bhattiprolu if (opts.newinstance) 4351bd79035SSukadev Bhattiprolu s = sget(fs_type, NULL, set_anon_super, NULL); 436482984f0SSukadev Bhattiprolu else 4371bd79035SSukadev Bhattiprolu s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); 438945cf2c7SSukadev Bhattiprolu 4391bd79035SSukadev Bhattiprolu if (IS_ERR(s)) 440fc14f2feSAl Viro return ERR_CAST(s); 4411bd79035SSukadev Bhattiprolu 4421bd79035SSukadev Bhattiprolu if (!s->s_root) { 4431bd79035SSukadev Bhattiprolu s->s_flags = flags; 4441bd79035SSukadev Bhattiprolu error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0); 445945cf2c7SSukadev Bhattiprolu if (error) 4461bd79035SSukadev Bhattiprolu goto out_undo_sget; 4471bd79035SSukadev Bhattiprolu s->s_flags |= MS_ACTIVE; 4481bd79035SSukadev Bhattiprolu } 449945cf2c7SSukadev Bhattiprolu 4501bd79035SSukadev Bhattiprolu memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts)); 4511bd79035SSukadev Bhattiprolu 4521bd79035SSukadev Bhattiprolu error = mknod_ptmx(s); 453945cf2c7SSukadev Bhattiprolu if (error) 45489468071SAl Viro goto out_undo_sget; 45589468071SAl Viro 456fc14f2feSAl Viro return dget(s->s_root); 457945cf2c7SSukadev Bhattiprolu 4581bd79035SSukadev Bhattiprolu out_undo_sget: 4596f5bbff9SAl Viro deactivate_locked_super(s); 460fc14f2feSAl Viro return ERR_PTR(error); 461482984f0SSukadev Bhattiprolu } 462482984f0SSukadev Bhattiprolu 4632a1b2dc0SSukadev Bhattiprolu #else 4642a1b2dc0SSukadev Bhattiprolu /* 4652a1b2dc0SSukadev Bhattiprolu * This supports only the legacy single-instance semantics (no 4662a1b2dc0SSukadev Bhattiprolu * multiple-instance semantics) 4672a1b2dc0SSukadev Bhattiprolu */ 468fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, int flags, 469fc14f2feSAl Viro const char *dev_name, void *data) 4702a1b2dc0SSukadev Bhattiprolu { 471fc14f2feSAl Viro return mount_single(fs_type, flags, data, devpts_fill_super); 4722a1b2dc0SSukadev Bhattiprolu } 4732a1b2dc0SSukadev Bhattiprolu #endif 4741da177e4SLinus Torvalds 475e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 476e76b7c01SSukadev Bhattiprolu { 477e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 478e76b7c01SSukadev Bhattiprolu 479e76b7c01SSukadev Bhattiprolu kfree(fsi); 4801f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 481e76b7c01SSukadev Bhattiprolu } 482e76b7c01SSukadev Bhattiprolu 4831da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 4841da177e4SLinus Torvalds .name = "devpts", 485fc14f2feSAl Viro .mount = devpts_mount, 486e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 4871da177e4SLinus Torvalds }; 4881da177e4SLinus Torvalds 4891da177e4SLinus Torvalds /* 4901da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 4911da177e4SLinus Torvalds * to the System V naming convention 4921da177e4SLinus Torvalds */ 4931da177e4SLinus Torvalds 49415f1a633SSukadev Bhattiprolu int devpts_new_index(struct inode *ptmx_inode) 495718a9163SSukadev Bhattiprolu { 496e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 497e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 498718a9163SSukadev Bhattiprolu int index; 4997ee7c12bSAlexey Dobriyan int ida_ret; 500718a9163SSukadev Bhattiprolu 501718a9163SSukadev Bhattiprolu retry: 502835aa440SAlan Cox if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) 503718a9163SSukadev Bhattiprolu return -ENOMEM; 504718a9163SSukadev Bhattiprolu 505718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 506e9aba515SKonstantin Khlebnikov if (pty_count >= pty_limit - 507e9aba515SKonstantin Khlebnikov (fsi->mount_opts.newinstance ? pty_reserve : 0)) { 508e9aba515SKonstantin Khlebnikov mutex_unlock(&allocated_ptys_lock); 509e9aba515SKonstantin Khlebnikov return -ENOSPC; 510e9aba515SKonstantin Khlebnikov } 511e9aba515SKonstantin Khlebnikov 512e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 5137ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 514718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 5157ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 516718a9163SSukadev Bhattiprolu goto retry; 517718a9163SSukadev Bhattiprolu return -EIO; 518718a9163SSukadev Bhattiprolu } 519718a9163SSukadev Bhattiprolu 520e9aba515SKonstantin Khlebnikov if (index >= fsi->mount_opts.max) { 521e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 522718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 523e9aba515SKonstantin Khlebnikov return -ENOSPC; 524718a9163SSukadev Bhattiprolu } 525a4834c10SKonstantin Khlebnikov pty_count++; 526718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 527718a9163SSukadev Bhattiprolu return index; 528718a9163SSukadev Bhattiprolu } 529718a9163SSukadev Bhattiprolu 53015f1a633SSukadev Bhattiprolu void devpts_kill_index(struct inode *ptmx_inode, int idx) 531718a9163SSukadev Bhattiprolu { 532e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 533e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 534e76b7c01SSukadev Bhattiprolu 535718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 536e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 537a4834c10SKonstantin Khlebnikov pty_count--; 538718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 539718a9163SSukadev Bhattiprolu } 540718a9163SSukadev Bhattiprolu 54115f1a633SSukadev Bhattiprolu int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) 5421da177e4SLinus Torvalds { 543835aa440SAlan Cox /* tty layer puts index from devpts_new_index() in here */ 544835aa440SAlan Cox int number = tty->index; 5451da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 5461da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 5471da177e4SLinus Torvalds struct dentry *dentry; 54859e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 54959e55e6cSSukadev Bhattiprolu struct inode *inode = new_inode(sb); 55059e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 55131af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 55231af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 553aa597bc1SAndrey Vagin int ret = 0; 55489a52e10SSukadev Bhattiprolu char s[12]; 5551da177e4SLinus Torvalds 5561da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 5571da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 5581da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 5591da177e4SLinus Torvalds 5601da177e4SLinus Torvalds if (!inode) 5611da177e4SLinus Torvalds return -ENOMEM; 5621da177e4SLinus Torvalds 563d0eafc7dSDavid Howells inode->i_ino = number + 3; 564d0eafc7dSDavid Howells inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); 565d0eafc7dSDavid Howells inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); 5661da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 56731af0abbSSukadev Bhattiprolu init_special_inode(inode, S_IFCHR|opts->mode, device); 5688e18e294STheodore Ts'o inode->i_private = tty; 569a6f37daaSSukadev Bhattiprolu tty->driver_data = inode; 5701da177e4SLinus Torvalds 57189a52e10SSukadev Bhattiprolu sprintf(s, "%d", number); 57289a52e10SSukadev Bhattiprolu 57359e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 57489a52e10SSukadev Bhattiprolu 57559e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 576b12d1259SAndrey Vagin if (dentry) { 57789a52e10SSukadev Bhattiprolu d_add(dentry, inode); 57859e55e6cSSukadev Bhattiprolu fsnotify_create(root->d_inode, dentry); 579aa597bc1SAndrey Vagin } else { 580aa597bc1SAndrey Vagin iput(inode); 581aa597bc1SAndrey Vagin ret = -ENOMEM; 5823972b7f6SFlorin Malita } 5831da177e4SLinus Torvalds 58459e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 5851da177e4SLinus Torvalds 586aa597bc1SAndrey Vagin return ret; 5871da177e4SLinus Torvalds } 5881da177e4SLinus Torvalds 58915f1a633SSukadev Bhattiprolu struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) 5901da177e4SLinus Torvalds { 591edfacdd6SSukadev Bhattiprolu struct dentry *dentry; 592edfacdd6SSukadev Bhattiprolu struct tty_struct *tty; 593edfacdd6SSukadev Bhattiprolu 594527b3e47SSukadev Bhattiprolu BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 5951da177e4SLinus Torvalds 596edfacdd6SSukadev Bhattiprolu /* Ensure dentry has not been deleted by devpts_pty_kill() */ 597edfacdd6SSukadev Bhattiprolu dentry = d_find_alias(pts_inode); 598edfacdd6SSukadev Bhattiprolu if (!dentry) 599527b3e47SSukadev Bhattiprolu return NULL; 600edfacdd6SSukadev Bhattiprolu 601edfacdd6SSukadev Bhattiprolu tty = NULL; 602edfacdd6SSukadev Bhattiprolu if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 603edfacdd6SSukadev Bhattiprolu tty = (struct tty_struct *)pts_inode->i_private; 604edfacdd6SSukadev Bhattiprolu 605edfacdd6SSukadev Bhattiprolu dput(dentry); 606edfacdd6SSukadev Bhattiprolu 607edfacdd6SSukadev Bhattiprolu return tty; 6081da177e4SLinus Torvalds } 6091da177e4SLinus Torvalds 61015f1a633SSukadev Bhattiprolu void devpts_pty_kill(struct tty_struct *tty) 6111da177e4SLinus Torvalds { 612a6f37daaSSukadev Bhattiprolu struct inode *inode = tty->driver_data; 61359e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(inode); 61459e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 615a6f37daaSSukadev Bhattiprolu struct dentry *dentry; 6161da177e4SLinus Torvalds 617a6f37daaSSukadev Bhattiprolu BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 618a6f37daaSSukadev Bhattiprolu 61959e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 620a6f37daaSSukadev Bhattiprolu 621a6f37daaSSukadev Bhattiprolu dentry = d_find_alias(inode); 6222a1b2dc0SSukadev Bhattiprolu 6236d6b77f1SMiklos Szeredi drop_nlink(inode); 6241da177e4SLinus Torvalds d_delete(dentry); 625835aa440SAlan Cox dput(dentry); /* d_alloc_name() in devpts_pty_new() */ 626835aa440SAlan Cox dput(dentry); /* d_find_alias above */ 627aa597bc1SAndrey Vagin 62859e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 6291da177e4SLinus Torvalds } 6301da177e4SLinus Torvalds 6311da177e4SLinus Torvalds static int __init init_devpts_fs(void) 6321da177e4SLinus Torvalds { 6331da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 634a4834c10SKonstantin Khlebnikov struct ctl_table_header *table; 635a4834c10SKonstantin Khlebnikov 6361da177e4SLinus Torvalds if (!err) { 637a4834c10SKonstantin Khlebnikov table = register_sysctl_table(pty_root_table); 6381da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 63993d5581eSAlan Cox if (IS_ERR(devpts_mnt)) { 6401da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 64193d5581eSAlan Cox unregister_filesystem(&devpts_fs_type); 642a4834c10SKonstantin Khlebnikov unregister_sysctl_table(table); 64393d5581eSAlan Cox } 6441da177e4SLinus Torvalds } 6451da177e4SLinus Torvalds return err; 6461da177e4SLinus Torvalds } 6471da177e4SLinus Torvalds module_init(init_devpts_fs) 648