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 1304541a2fSFabian Frederick #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 1404541a2fSFabian Frederick 151da177e4SLinus Torvalds #include <linux/module.h> 161da177e4SLinus Torvalds #include <linux/init.h> 171da177e4SLinus Torvalds #include <linux/fs.h> 181da177e4SLinus Torvalds #include <linux/sched.h> 191da177e4SLinus Torvalds #include <linux/namei.h> 205a0e3ad6STejun Heo #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/mount.h> 221da177e4SLinus Torvalds #include <linux/tty.h> 23718a9163SSukadev Bhattiprolu #include <linux/mutex.h> 241fd7317dSNick Black #include <linux/magic.h> 25718a9163SSukadev Bhattiprolu #include <linux/idr.h> 261da177e4SLinus Torvalds #include <linux/devpts_fs.h> 277a673c6bSDomen Puncer #include <linux/parser.h> 283972b7f6SFlorin Malita #include <linux/fsnotify.h> 29b87a267eSMiklos Szeredi #include <linux/seq_file.h> 301da177e4SLinus Torvalds 31b87a267eSMiklos Szeredi #define DEVPTS_DEFAULT_MODE 0600 321f8f1e29SSukadev Bhattiprolu /* 331f8f1e29SSukadev Bhattiprolu * ptmx is a new node in /dev/pts and will be unused in legacy (single- 341f8f1e29SSukadev Bhattiprolu * instance) mode. To prevent surprises in user space, set permissions of 351f8f1e29SSukadev Bhattiprolu * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful 361f8f1e29SSukadev Bhattiprolu * permissions. 371f8f1e29SSukadev Bhattiprolu */ 381f8f1e29SSukadev Bhattiprolu #define DEVPTS_DEFAULT_PTMX_MODE 0000 39527b3e47SSukadev Bhattiprolu #define PTMX_MINOR 2 40b87a267eSMiklos Szeredi 41a4834c10SKonstantin Khlebnikov /* 42a4834c10SKonstantin Khlebnikov * sysctl support for setting limits on the number of Unix98 ptys allocated. 43a4834c10SKonstantin Khlebnikov * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly. 44a4834c10SKonstantin Khlebnikov */ 45a4834c10SKonstantin Khlebnikov static int pty_limit = NR_UNIX98_PTY_DEFAULT; 46e9aba515SKonstantin Khlebnikov static int pty_reserve = NR_UNIX98_PTY_RESERVE; 47a4834c10SKonstantin Khlebnikov static int pty_limit_min; 48e9aba515SKonstantin Khlebnikov static int pty_limit_max = INT_MAX; 49a4834c10SKonstantin Khlebnikov static int pty_count; 50a4834c10SKonstantin Khlebnikov 51a4834c10SKonstantin Khlebnikov static struct ctl_table pty_table[] = { 52a4834c10SKonstantin Khlebnikov { 53a4834c10SKonstantin Khlebnikov .procname = "max", 54a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 55a4834c10SKonstantin Khlebnikov .mode = 0644, 56a4834c10SKonstantin Khlebnikov .data = &pty_limit, 57a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec_minmax, 58a4834c10SKonstantin Khlebnikov .extra1 = &pty_limit_min, 59a4834c10SKonstantin Khlebnikov .extra2 = &pty_limit_max, 60a4834c10SKonstantin Khlebnikov }, { 61e9aba515SKonstantin Khlebnikov .procname = "reserve", 62e9aba515SKonstantin Khlebnikov .maxlen = sizeof(int), 63e9aba515SKonstantin Khlebnikov .mode = 0644, 64e9aba515SKonstantin Khlebnikov .data = &pty_reserve, 65e9aba515SKonstantin Khlebnikov .proc_handler = proc_dointvec_minmax, 66e9aba515SKonstantin Khlebnikov .extra1 = &pty_limit_min, 67e9aba515SKonstantin Khlebnikov .extra2 = &pty_limit_max, 68e9aba515SKonstantin Khlebnikov }, { 69a4834c10SKonstantin Khlebnikov .procname = "nr", 70a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 71a4834c10SKonstantin Khlebnikov .mode = 0444, 72a4834c10SKonstantin Khlebnikov .data = &pty_count, 73a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec, 74a4834c10SKonstantin Khlebnikov }, 75a4834c10SKonstantin Khlebnikov {} 76a4834c10SKonstantin Khlebnikov }; 77a4834c10SKonstantin Khlebnikov 78a4834c10SKonstantin Khlebnikov static struct ctl_table pty_kern_table[] = { 79a4834c10SKonstantin Khlebnikov { 80a4834c10SKonstantin Khlebnikov .procname = "pty", 81a4834c10SKonstantin Khlebnikov .mode = 0555, 82a4834c10SKonstantin Khlebnikov .child = pty_table, 83a4834c10SKonstantin Khlebnikov }, 84a4834c10SKonstantin Khlebnikov {} 85a4834c10SKonstantin Khlebnikov }; 86a4834c10SKonstantin Khlebnikov 87a4834c10SKonstantin Khlebnikov static struct ctl_table pty_root_table[] = { 88a4834c10SKonstantin Khlebnikov { 89a4834c10SKonstantin Khlebnikov .procname = "kernel", 90a4834c10SKonstantin Khlebnikov .mode = 0555, 91a4834c10SKonstantin Khlebnikov .child = pty_kern_table, 92a4834c10SKonstantin Khlebnikov }, 93a4834c10SKonstantin Khlebnikov {} 94a4834c10SKonstantin Khlebnikov }; 95a4834c10SKonstantin Khlebnikov 96718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 97718a9163SSukadev Bhattiprolu 9831af0abbSSukadev Bhattiprolu struct pts_mount_opts { 991da177e4SLinus Torvalds int setuid; 1001da177e4SLinus Torvalds int setgid; 101f04c6ce2SEric W. Biederman kuid_t uid; 102f04c6ce2SEric W. Biederman kgid_t gid; 1031da177e4SLinus Torvalds umode_t mode; 1041f8f1e29SSukadev Bhattiprolu umode_t ptmxmode; 105eedf265aSEric W. Biederman int reserve; 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 {Opt_ptmxmode, "ptmxmode=%o"}, 1192a1b2dc0SSukadev Bhattiprolu {Opt_newinstance, "newinstance"}, 120e9aba515SKonstantin Khlebnikov {Opt_max, "max=%d"}, 1217a673c6bSDomen Puncer {Opt_err, NULL} 1227a673c6bSDomen Puncer }; 1237a673c6bSDomen Puncer 124e76b7c01SSukadev Bhattiprolu struct pts_fs_info { 125e76b7c01SSukadev Bhattiprolu struct ida allocated_ptys; 12631af0abbSSukadev Bhattiprolu struct pts_mount_opts mount_opts; 12767245ff3SLinus Torvalds struct super_block *sb; 1281f8f1e29SSukadev Bhattiprolu struct dentry *ptmx_dentry; 129e76b7c01SSukadev Bhattiprolu }; 130e76b7c01SSukadev Bhattiprolu 131e76b7c01SSukadev Bhattiprolu static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) 132e76b7c01SSukadev Bhattiprolu { 133e76b7c01SSukadev Bhattiprolu return sb->s_fs_info; 134e76b7c01SSukadev Bhattiprolu } 135e76b7c01SSukadev Bhattiprolu 136311fc65cSEric W. Biederman static int devpts_ptmx_path(struct path *path) 137311fc65cSEric W. Biederman { 138311fc65cSEric W. Biederman struct super_block *sb; 139311fc65cSEric W. Biederman int err; 140311fc65cSEric W. Biederman 141311fc65cSEric W. Biederman /* Is a devpts filesystem at "pts" in the same directory? */ 142311fc65cSEric W. Biederman err = path_pts(path); 143311fc65cSEric W. Biederman if (err) 144311fc65cSEric W. Biederman return err; 145311fc65cSEric W. Biederman 146311fc65cSEric W. Biederman /* Is the path the root of a devpts filesystem? */ 147311fc65cSEric W. Biederman sb = path->mnt->mnt_sb; 148311fc65cSEric W. Biederman if ((sb->s_magic != DEVPTS_SUPER_MAGIC) || 149311fc65cSEric W. Biederman (path->mnt->mnt_root != sb->s_root)) 150311fc65cSEric W. Biederman return -ENODEV; 151311fc65cSEric W. Biederman 152311fc65cSEric W. Biederman return 0; 153311fc65cSEric W. Biederman } 154311fc65cSEric W. Biederman 1554e15f760SChristian Brauner /* 1564e15f760SChristian Brauner * Try to find a suitable devpts filesystem. We support the following 1574e15f760SChristian Brauner * scenarios: 1584e15f760SChristian Brauner * - The ptmx device node is located in the same directory as the devpts 1594e15f760SChristian Brauner * mount where the pts device nodes are located. 1604e15f760SChristian Brauner * This is e.g. the case when calling open on the /dev/pts/ptmx device 1614e15f760SChristian Brauner * node when the devpts filesystem is mounted at /dev/pts. 1624e15f760SChristian Brauner * - The ptmx device node is located outside the devpts filesystem mount 1634e15f760SChristian Brauner * where the pts device nodes are located. For example, the ptmx device 1644e15f760SChristian Brauner * is a symlink, separate device node, or bind-mount. 1654e15f760SChristian Brauner * A supported scenario is bind-mounting /dev/pts/ptmx to /dev/ptmx and 1664e15f760SChristian Brauner * then calling open on /dev/ptmx. In this case a suitable pts 1674e15f760SChristian Brauner * subdirectory can be found in the common parent directory /dev of the 1684e15f760SChristian Brauner * devpts mount and the ptmx bind-mount, after resolving the /dev/ptmx 1694e15f760SChristian Brauner * bind-mount. 1704e15f760SChristian Brauner * If no suitable pts subdirectory can be found this function will fail. 1714e15f760SChristian Brauner * This is e.g. the case when bind-mounting /dev/pts/ptmx to /ptmx. 1724e15f760SChristian Brauner */ 173311fc65cSEric W. Biederman struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) 174311fc65cSEric W. Biederman { 175311fc65cSEric W. Biederman struct path path; 1767d71109dSChristian Brauner int err = 0; 177311fc65cSEric W. Biederman 178311fc65cSEric W. Biederman path = filp->f_path; 179311fc65cSEric W. Biederman path_get(&path); 180311fc65cSEric W. Biederman 181a319b01dSChristian Brauner /* Walk upward while the start point is a bind mount of 182a319b01dSChristian Brauner * a single file. 183a319b01dSChristian Brauner */ 184a319b01dSChristian Brauner while (path.mnt->mnt_root == path.dentry) 185a319b01dSChristian Brauner if (follow_up(&path) == 0) 186a319b01dSChristian Brauner break; 187a319b01dSChristian Brauner 188a319b01dSChristian Brauner /* devpts_ptmx_path() finds a devpts fs or returns an error. */ 189a319b01dSChristian Brauner if ((path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) || 190a319b01dSChristian Brauner (DEVPTS_SB(path.mnt->mnt_sb) != fsi)) 191311fc65cSEric W. Biederman err = devpts_ptmx_path(&path); 192311fc65cSEric W. Biederman dput(path.dentry); 193a319b01dSChristian Brauner if (!err) { 194a319b01dSChristian Brauner if (DEVPTS_SB(path.mnt->mnt_sb) == fsi) 195a319b01dSChristian Brauner return path.mnt; 196a319b01dSChristian Brauner 197a319b01dSChristian Brauner err = -ENODEV; 198a319b01dSChristian Brauner } 199a319b01dSChristian Brauner 200311fc65cSEric W. Biederman mntput(path.mnt); 201c9cc8d01SEric Biggers return ERR_PTR(err); 202311fc65cSEric W. Biederman } 2037d71109dSChristian Brauner 204143c97ccSLinus Torvalds struct pts_fs_info *devpts_acquire(struct file *filp) 20559e55e6cSSukadev Bhattiprolu { 206eedf265aSEric W. Biederman struct pts_fs_info *result; 207eedf265aSEric W. Biederman struct path path; 208eedf265aSEric W. Biederman struct super_block *sb; 209eedf265aSEric W. Biederman 210eedf265aSEric W. Biederman path = filp->f_path; 211eedf265aSEric W. Biederman path_get(&path); 212eedf265aSEric W. Biederman 2137d71109dSChristian Brauner /* Has the devpts filesystem already been found? */ 2147d71109dSChristian Brauner if (path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) { 2157d71109dSChristian Brauner int err; 2167d71109dSChristian Brauner 217311fc65cSEric W. Biederman err = devpts_ptmx_path(&path); 218eedf265aSEric W. Biederman if (err) { 219eedf265aSEric W. Biederman result = ERR_PTR(err); 220eedf265aSEric W. Biederman goto out; 221eedf265aSEric W. Biederman } 2227d71109dSChristian Brauner } 223eedf265aSEric W. Biederman 224eedf265aSEric W. Biederman /* 225eedf265aSEric W. Biederman * pty code needs to hold extra references in case of last /dev/tty close 226eedf265aSEric W. Biederman */ 227311fc65cSEric W. Biederman sb = path.mnt->mnt_sb; 228eedf265aSEric W. Biederman atomic_inc(&sb->s_active); 229eedf265aSEric W. Biederman result = DEVPTS_SB(sb); 230eedf265aSEric W. Biederman 231eedf265aSEric W. Biederman out: 232eedf265aSEric W. Biederman path_put(&path); 233eedf265aSEric W. Biederman return result; 234eedf265aSEric W. Biederman } 235eedf265aSEric W. Biederman 236eedf265aSEric W. Biederman void devpts_release(struct pts_fs_info *fsi) 237eedf265aSEric W. Biederman { 238eedf265aSEric W. Biederman deactivate_super(fsi->sb); 23959e55e6cSSukadev Bhattiprolu } 24059e55e6cSSukadev Bhattiprolu 2412a1b2dc0SSukadev Bhattiprolu #define PARSE_MOUNT 0 2422a1b2dc0SSukadev Bhattiprolu #define PARSE_REMOUNT 1 2432a1b2dc0SSukadev Bhattiprolu 2441f71ebedSSukadev Bhattiprolu /* 2451f71ebedSSukadev Bhattiprolu * parse_mount_options(): 2461f71ebedSSukadev Bhattiprolu * Set @opts to mount options specified in @data. If an option is not 247eedf265aSEric W. Biederman * specified in @data, set it to its default value. 2481f71ebedSSukadev Bhattiprolu * 2491f71ebedSSukadev Bhattiprolu * Note: @data may be NULL (in which case all options are set to default). 2501f71ebedSSukadev Bhattiprolu */ 2512a1b2dc0SSukadev Bhattiprolu static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) 2521da177e4SLinus Torvalds { 2537a673c6bSDomen Puncer char *p; 254f04c6ce2SEric W. Biederman kuid_t uid; 255f04c6ce2SEric W. Biederman kgid_t gid; 2561da177e4SLinus Torvalds 25731af0abbSSukadev Bhattiprolu opts->setuid = 0; 25831af0abbSSukadev Bhattiprolu opts->setgid = 0; 259f04c6ce2SEric W. Biederman opts->uid = GLOBAL_ROOT_UID; 260f04c6ce2SEric W. Biederman opts->gid = GLOBAL_ROOT_GID; 26131af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 2621f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 263e9aba515SKonstantin Khlebnikov opts->max = NR_UNIX98_PTY_MAX; 2647a673c6bSDomen Puncer 265eedf265aSEric W. Biederman /* Only allow instances mounted from the initial mount 266eedf265aSEric W. Biederman * namespace to tap the reserve pool of ptys. 267eedf265aSEric W. Biederman */ 2682a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 269eedf265aSEric W. Biederman opts->reserve = 270eedf265aSEric W. Biederman (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); 2712a1b2dc0SSukadev Bhattiprolu 2727a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 2737a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 2747a673c6bSDomen Puncer int token; 2757a673c6bSDomen Puncer int option; 2767a673c6bSDomen Puncer 2777a673c6bSDomen Puncer if (!*p) 2781da177e4SLinus Torvalds continue; 2797a673c6bSDomen Puncer 2807a673c6bSDomen Puncer token = match_token(p, tokens, args); 2817a673c6bSDomen Puncer switch (token) { 2827a673c6bSDomen Puncer case Opt_uid: 2837a673c6bSDomen Puncer if (match_int(&args[0], &option)) 2847a673c6bSDomen Puncer return -EINVAL; 285f04c6ce2SEric W. Biederman uid = make_kuid(current_user_ns(), option); 286f04c6ce2SEric W. Biederman if (!uid_valid(uid)) 287f04c6ce2SEric W. Biederman return -EINVAL; 288f04c6ce2SEric W. Biederman opts->uid = uid; 28931af0abbSSukadev Bhattiprolu opts->setuid = 1; 2907a673c6bSDomen Puncer break; 2917a673c6bSDomen Puncer case Opt_gid: 2927a673c6bSDomen Puncer if (match_int(&args[0], &option)) 2937a673c6bSDomen Puncer return -EINVAL; 294f04c6ce2SEric W. Biederman gid = make_kgid(current_user_ns(), option); 295f04c6ce2SEric W. Biederman if (!gid_valid(gid)) 296f04c6ce2SEric W. Biederman return -EINVAL; 297f04c6ce2SEric W. Biederman opts->gid = gid; 29831af0abbSSukadev Bhattiprolu opts->setgid = 1; 2997a673c6bSDomen Puncer break; 3007a673c6bSDomen Puncer case Opt_mode: 3017a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 3027a673c6bSDomen Puncer return -EINVAL; 30331af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 3047a673c6bSDomen Puncer break; 3051f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 3061f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 3071f8f1e29SSukadev Bhattiprolu return -EINVAL; 3081f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 3091f8f1e29SSukadev Bhattiprolu break; 3102a1b2dc0SSukadev Bhattiprolu case Opt_newinstance: 3112a1b2dc0SSukadev Bhattiprolu break; 312e9aba515SKonstantin Khlebnikov case Opt_max: 313e9aba515SKonstantin Khlebnikov if (match_int(&args[0], &option) || 314e9aba515SKonstantin Khlebnikov option < 0 || option > NR_UNIX98_PTY_MAX) 315e9aba515SKonstantin Khlebnikov return -EINVAL; 316e9aba515SKonstantin Khlebnikov opts->max = option; 317e9aba515SKonstantin Khlebnikov break; 3187a673c6bSDomen Puncer default: 31904541a2fSFabian Frederick pr_err("called with bogus options\n"); 3201da177e4SLinus Torvalds return -EINVAL; 3211da177e4SLinus Torvalds } 3221da177e4SLinus Torvalds } 3231da177e4SLinus Torvalds 3241da177e4SLinus Torvalds return 0; 3251da177e4SLinus Torvalds } 3261da177e4SLinus Torvalds 3271f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 32853af8ee4SSukadev Bhattiprolu { 3291f8f1e29SSukadev Bhattiprolu int mode; 3301f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 3311f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 3321f8f1e29SSukadev Bhattiprolu struct inode *inode; 3331f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 33453af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 33553af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 336e98d4137SEric W. Biederman kuid_t ptmx_uid = current_fsuid(); 337e98d4137SEric W. Biederman kgid_t ptmx_gid = current_fsgid(); 33853af8ee4SSukadev Bhattiprolu 3395955102cSAl Viro inode_lock(d_inode(root)); 3401f8f1e29SSukadev Bhattiprolu 3411f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 3421f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 3431f8f1e29SSukadev Bhattiprolu rc = 0; 3441f8f1e29SSukadev Bhattiprolu goto out; 3451f8f1e29SSukadev Bhattiprolu } 3461f8f1e29SSukadev Bhattiprolu 3471f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 3481f8f1e29SSukadev Bhattiprolu if (!dentry) { 34904541a2fSFabian Frederick pr_err("Unable to alloc dentry for ptmx node\n"); 3501f8f1e29SSukadev Bhattiprolu goto out; 3511f8f1e29SSukadev Bhattiprolu } 3521f8f1e29SSukadev Bhattiprolu 3531f8f1e29SSukadev Bhattiprolu /* 3541f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 3551f8f1e29SSukadev Bhattiprolu */ 3561f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 3571f8f1e29SSukadev Bhattiprolu if (!inode) { 35804541a2fSFabian Frederick pr_err("Unable to alloc inode for ptmx node\n"); 3591f8f1e29SSukadev Bhattiprolu dput(dentry); 3601f8f1e29SSukadev Bhattiprolu goto out; 3611f8f1e29SSukadev Bhattiprolu } 3621f8f1e29SSukadev Bhattiprolu 3631f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 364078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 3651f8f1e29SSukadev Bhattiprolu 3661f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 3671f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 368e98d4137SEric W. Biederman inode->i_uid = ptmx_uid; 369e98d4137SEric W. Biederman inode->i_gid = ptmx_gid; 3701f8f1e29SSukadev Bhattiprolu 3711f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 3721f8f1e29SSukadev Bhattiprolu 3731f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 3741f8f1e29SSukadev Bhattiprolu rc = 0; 3751f8f1e29SSukadev Bhattiprolu out: 3765955102cSAl Viro inode_unlock(d_inode(root)); 3771f8f1e29SSukadev Bhattiprolu return rc; 3781f8f1e29SSukadev Bhattiprolu } 3791f8f1e29SSukadev Bhattiprolu 3801f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 3811f8f1e29SSukadev Bhattiprolu { 3821f8f1e29SSukadev Bhattiprolu struct inode *inode; 3831f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 3842b0143b5SDavid Howells inode = d_inode(fsi->ptmx_dentry); 3851f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 3861f8f1e29SSukadev Bhattiprolu } 3871f8f1e29SSukadev Bhattiprolu } 3881f8f1e29SSukadev Bhattiprolu 3891f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 3901f8f1e29SSukadev Bhattiprolu { 3911f8f1e29SSukadev Bhattiprolu int err; 3921f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 3931f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 3941f8f1e29SSukadev Bhattiprolu 3952a1b2dc0SSukadev Bhattiprolu err = parse_mount_options(data, PARSE_REMOUNT, opts); 3961f8f1e29SSukadev Bhattiprolu 3971f8f1e29SSukadev Bhattiprolu /* 3981f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 3991f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 4001f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 4011f8f1e29SSukadev Bhattiprolu * so do this even on error return. 4021f8f1e29SSukadev Bhattiprolu */ 4031f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 4041f8f1e29SSukadev Bhattiprolu 4051f8f1e29SSukadev Bhattiprolu return err; 40653af8ee4SSukadev Bhattiprolu } 40753af8ee4SSukadev Bhattiprolu 40834c80b1dSAl Viro static int devpts_show_options(struct seq_file *seq, struct dentry *root) 409b87a267eSMiklos Szeredi { 41034c80b1dSAl Viro struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); 41131af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 41231af0abbSSukadev Bhattiprolu 41331af0abbSSukadev Bhattiprolu if (opts->setuid) 41404541a2fSFabian Frederick seq_printf(seq, ",uid=%u", 41504541a2fSFabian Frederick from_kuid_munged(&init_user_ns, opts->uid)); 41631af0abbSSukadev Bhattiprolu if (opts->setgid) 41704541a2fSFabian Frederick seq_printf(seq, ",gid=%u", 41804541a2fSFabian Frederick from_kgid_munged(&init_user_ns, opts->gid)); 41931af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 4201f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 421e9aba515SKonstantin Khlebnikov if (opts->max < NR_UNIX98_PTY_MAX) 422e9aba515SKonstantin Khlebnikov seq_printf(seq, ",max=%d", opts->max); 423b87a267eSMiklos Szeredi 424b87a267eSMiklos Szeredi return 0; 425b87a267eSMiklos Szeredi } 426b87a267eSMiklos Szeredi 427ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 4281da177e4SLinus Torvalds .statfs = simple_statfs, 4291da177e4SLinus Torvalds .remount_fs = devpts_remount, 430b87a267eSMiklos Szeredi .show_options = devpts_show_options, 4311da177e4SLinus Torvalds }; 4321da177e4SLinus Torvalds 43367245ff3SLinus Torvalds static void *new_pts_fs_info(struct super_block *sb) 434e76b7c01SSukadev Bhattiprolu { 435e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 436e76b7c01SSukadev Bhattiprolu 437e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 438e76b7c01SSukadev Bhattiprolu if (!fsi) 439e76b7c01SSukadev Bhattiprolu return NULL; 440e76b7c01SSukadev Bhattiprolu 441e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 44231af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 4431f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 44467245ff3SLinus Torvalds fsi->sb = sb; 445e76b7c01SSukadev Bhattiprolu 446e76b7c01SSukadev Bhattiprolu return fsi; 447e76b7c01SSukadev Bhattiprolu } 448e76b7c01SSukadev Bhattiprolu 4491da177e4SLinus Torvalds static int 4501da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 4511da177e4SLinus Torvalds { 4521da177e4SLinus Torvalds struct inode *inode; 453dee87d47SEric W. Biederman int error; 4541da177e4SLinus Torvalds 455cc50a07aSEric W. Biederman s->s_iflags &= ~SB_I_NODEV; 4561da177e4SLinus Torvalds s->s_blocksize = 1024; 4571da177e4SLinus Torvalds s->s_blocksize_bits = 10; 4581da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 4591da177e4SLinus Torvalds s->s_op = &devpts_sops; 4601da177e4SLinus Torvalds s->s_time_gran = 1; 4611da177e4SLinus Torvalds 462dee87d47SEric W. Biederman error = -ENOMEM; 46367245ff3SLinus Torvalds s->s_fs_info = new_pts_fs_info(s); 464e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 465e76b7c01SSukadev Bhattiprolu goto fail; 466e76b7c01SSukadev Bhattiprolu 467dee87d47SEric W. Biederman error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts); 468dee87d47SEric W. Biederman if (error) 469dee87d47SEric W. Biederman goto fail; 470dee87d47SEric W. Biederman 471dee87d47SEric W. Biederman error = -ENOMEM; 4721da177e4SLinus Torvalds inode = new_inode(s); 4731da177e4SLinus Torvalds if (!inode) 4743850aba7SAl Viro goto fail; 4751da177e4SLinus Torvalds inode->i_ino = 1; 476078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 4771da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 4781da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 4791da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 480bfe86848SMiklos Szeredi set_nlink(inode, 2); 4811da177e4SLinus Torvalds 48248fde701SAl Viro s->s_root = d_make_root(inode); 483180d9044SEric W. Biederman if (!s->s_root) { 48404541a2fSFabian Frederick pr_err("get root dentry failed\n"); 485180d9044SEric W. Biederman goto fail; 486180d9044SEric W. Biederman } 487e76b7c01SSukadev Bhattiprolu 488180d9044SEric W. Biederman error = mknod_ptmx(s); 489180d9044SEric W. Biederman if (error) 490180d9044SEric W. Biederman goto fail_dput; 491180d9044SEric W. Biederman 492180d9044SEric W. Biederman return 0; 493180d9044SEric W. Biederman fail_dput: 494180d9044SEric W. Biederman dput(s->s_root); 495180d9044SEric W. Biederman s->s_root = NULL; 4961da177e4SLinus Torvalds fail: 497dee87d47SEric W. Biederman return error; 4981da177e4SLinus Torvalds } 4991da177e4SLinus Torvalds 5002a1b2dc0SSukadev Bhattiprolu /* 501fc14f2feSAl Viro * devpts_mount() 502289f00e2SSukadev Bhattiprolu * 503eedf265aSEric W. Biederman * Mount a new (private) instance of devpts. PTYs created in this 504eedf265aSEric W. Biederman * instance are independent of the PTYs in other devpts instances. 505d4076ac5SSukadev Bhattiprolu */ 506fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, 507fc14f2feSAl Viro int flags, const char *dev_name, void *data) 5081da177e4SLinus Torvalds { 509c1b241f0SEric W. Biederman return mount_nodev(fs_type, flags, data, devpts_fill_super); 510482984f0SSukadev Bhattiprolu } 511482984f0SSukadev Bhattiprolu 512e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 513e76b7c01SSukadev Bhattiprolu { 514e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 515e76b7c01SSukadev Bhattiprolu 51640b320e1SEric W. Biederman if (fsi) 51766da0e1fSIlija Hadzic ida_destroy(&fsi->allocated_ptys); 518e76b7c01SSukadev Bhattiprolu kfree(fsi); 5191f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 520e76b7c01SSukadev Bhattiprolu } 521e76b7c01SSukadev Bhattiprolu 5221da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 5231da177e4SLinus Torvalds .name = "devpts", 524fc14f2feSAl Viro .mount = devpts_mount, 525e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 526cc50a07aSEric W. Biederman .fs_flags = FS_USERNS_MOUNT, 5271da177e4SLinus Torvalds }; 5281da177e4SLinus Torvalds 5291da177e4SLinus Torvalds /* 5301da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 5311da177e4SLinus Torvalds * to the System V naming convention 5321da177e4SLinus Torvalds */ 5331da177e4SLinus Torvalds 53467245ff3SLinus Torvalds int devpts_new_index(struct pts_fs_info *fsi) 535718a9163SSukadev Bhattiprolu { 536718a9163SSukadev Bhattiprolu int index; 5377ee7c12bSAlexey Dobriyan int ida_ret; 538718a9163SSukadev Bhattiprolu 539718a9163SSukadev Bhattiprolu retry: 540835aa440SAlan Cox if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) 541718a9163SSukadev Bhattiprolu return -ENOMEM; 542718a9163SSukadev Bhattiprolu 543718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 544eedf265aSEric W. Biederman if (pty_count >= (pty_limit - 545eedf265aSEric W. Biederman (fsi->mount_opts.reserve ? 0 : pty_reserve))) { 546e9aba515SKonstantin Khlebnikov mutex_unlock(&allocated_ptys_lock); 547e9aba515SKonstantin Khlebnikov return -ENOSPC; 548e9aba515SKonstantin Khlebnikov } 549e9aba515SKonstantin Khlebnikov 550e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 5517ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 552718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 5537ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 554718a9163SSukadev Bhattiprolu goto retry; 555718a9163SSukadev Bhattiprolu return -EIO; 556718a9163SSukadev Bhattiprolu } 557718a9163SSukadev Bhattiprolu 558e9aba515SKonstantin Khlebnikov if (index >= fsi->mount_opts.max) { 559e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 560718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 561e9aba515SKonstantin Khlebnikov return -ENOSPC; 562718a9163SSukadev Bhattiprolu } 563a4834c10SKonstantin Khlebnikov pty_count++; 564718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 565718a9163SSukadev Bhattiprolu return index; 566718a9163SSukadev Bhattiprolu } 567718a9163SSukadev Bhattiprolu 56867245ff3SLinus Torvalds void devpts_kill_index(struct pts_fs_info *fsi, int idx) 569718a9163SSukadev Bhattiprolu { 570718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 571e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 572a4834c10SKonstantin Khlebnikov pty_count--; 573718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 574718a9163SSukadev Bhattiprolu } 575718a9163SSukadev Bhattiprolu 5761dcb8e6dSJiri Slaby /** 5771dcb8e6dSJiri Slaby * devpts_pty_new -- create a new inode in /dev/pts/ 5781dcb8e6dSJiri Slaby * @ptmx_inode: inode of the master 5791dcb8e6dSJiri Slaby * @device: major+minor of the node to be created 5801dcb8e6dSJiri Slaby * @index: used as a name of the node 5811dcb8e6dSJiri Slaby * @priv: what's given back by devpts_get_priv 5821dcb8e6dSJiri Slaby * 5831dcb8e6dSJiri Slaby * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill. 5841dcb8e6dSJiri Slaby */ 5858ead9dd5SLinus Torvalds struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) 5861da177e4SLinus Torvalds { 5871da177e4SLinus Torvalds struct dentry *dentry; 588eedf265aSEric W. Biederman struct super_block *sb = fsi->sb; 589162b97cfSJiri Slaby struct inode *inode; 5909ce71148SJosh Triplett struct dentry *root; 5919ce71148SJosh Triplett struct pts_mount_opts *opts; 59289a52e10SSukadev Bhattiprolu char s[12]; 5931da177e4SLinus Torvalds 5949ce71148SJosh Triplett root = sb->s_root; 5959ce71148SJosh Triplett opts = &fsi->mount_opts; 5969ce71148SJosh Triplett 597162b97cfSJiri Slaby inode = new_inode(sb); 5981da177e4SLinus Torvalds if (!inode) 599162b97cfSJiri Slaby return ERR_PTR(-ENOMEM); 6001da177e4SLinus Torvalds 601f11afb61SJiri Slaby inode->i_ino = index + 3; 602d0eafc7dSDavid Howells inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); 603d0eafc7dSDavid Howells inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); 604078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 6058ead9dd5SLinus Torvalds init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index)); 6061da177e4SLinus Torvalds 607f11afb61SJiri Slaby sprintf(s, "%d", index); 60889a52e10SSukadev Bhattiprolu 60959e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 610b12d1259SAndrey Vagin if (dentry) { 6118ead9dd5SLinus Torvalds dentry->d_fsdata = priv; 61289a52e10SSukadev Bhattiprolu d_add(dentry, inode); 6132b0143b5SDavid Howells fsnotify_create(d_inode(root), dentry); 614aa597bc1SAndrey Vagin } else { 615aa597bc1SAndrey Vagin iput(inode); 6168ead9dd5SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 6173972b7f6SFlorin Malita } 6181da177e4SLinus Torvalds 6198ead9dd5SLinus Torvalds return dentry; 6201da177e4SLinus Torvalds } 6211da177e4SLinus Torvalds 6221dcb8e6dSJiri Slaby /** 6231dcb8e6dSJiri Slaby * devpts_get_priv -- get private data for a slave 6241dcb8e6dSJiri Slaby * @pts_inode: inode of the slave 6251dcb8e6dSJiri Slaby * 6261dcb8e6dSJiri Slaby * Returns whatever was passed as priv in devpts_pty_new for a given inode. 6271dcb8e6dSJiri Slaby */ 6288ead9dd5SLinus Torvalds void *devpts_get_priv(struct dentry *dentry) 6291da177e4SLinus Torvalds { 6303e423945SLinus Torvalds if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC) 6313e423945SLinus Torvalds return NULL; 6328ead9dd5SLinus Torvalds return dentry->d_fsdata; 6331da177e4SLinus Torvalds } 6341da177e4SLinus Torvalds 6351dcb8e6dSJiri Slaby /** 6361dcb8e6dSJiri Slaby * devpts_pty_kill -- remove inode form /dev/pts/ 6371dcb8e6dSJiri Slaby * @inode: inode of the slave to be removed 6381dcb8e6dSJiri Slaby * 6391dcb8e6dSJiri Slaby * This is an inverse operation of devpts_pty_new. 6401dcb8e6dSJiri Slaby */ 6418ead9dd5SLinus Torvalds void devpts_pty_kill(struct dentry *dentry) 6421da177e4SLinus Torvalds { 6438ead9dd5SLinus Torvalds WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC); 6441da177e4SLinus Torvalds 6458ead9dd5SLinus Torvalds dentry->d_fsdata = NULL; 6468ead9dd5SLinus Torvalds drop_nlink(dentry->d_inode); 6471da177e4SLinus Torvalds d_delete(dentry); 648835aa440SAlan Cox dput(dentry); /* d_alloc_name() in devpts_pty_new() */ 6491da177e4SLinus Torvalds } 6501da177e4SLinus Torvalds 6511da177e4SLinus Torvalds static int __init init_devpts_fs(void) 6521da177e4SLinus Torvalds { 6531da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 6541da177e4SLinus Torvalds if (!err) { 655eedf265aSEric W. Biederman register_sysctl_table(pty_root_table); 6561da177e4SLinus Torvalds } 6571da177e4SLinus Torvalds return err; 6581da177e4SLinus Torvalds } 6591da177e4SLinus Torvalds module_init(init_devpts_fs) 660