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 155311fc65cSEric W. Biederman struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) 156311fc65cSEric W. Biederman { 157311fc65cSEric W. Biederman struct path path; 1587d71109dSChristian Brauner int err = 0; 159311fc65cSEric W. Biederman 160311fc65cSEric W. Biederman path = filp->f_path; 161311fc65cSEric W. Biederman path_get(&path); 162311fc65cSEric W. Biederman 1637d71109dSChristian Brauner /* Has the devpts filesystem already been found? */ 1647d71109dSChristian Brauner if (path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) 165311fc65cSEric W. Biederman err = devpts_ptmx_path(&path); 166311fc65cSEric W. Biederman dput(path.dentry); 167311fc65cSEric W. Biederman if (err) { 168311fc65cSEric W. Biederman mntput(path.mnt); 169c9cc8d01SEric Biggers return ERR_PTR(err); 170311fc65cSEric W. Biederman } 1717d71109dSChristian Brauner 172311fc65cSEric W. Biederman if (DEVPTS_SB(path.mnt->mnt_sb) != fsi) { 173311fc65cSEric W. Biederman mntput(path.mnt); 174c9cc8d01SEric Biggers return ERR_PTR(-ENODEV); 175311fc65cSEric W. Biederman } 1767d71109dSChristian Brauner 177311fc65cSEric W. Biederman return path.mnt; 178311fc65cSEric W. Biederman } 179311fc65cSEric W. Biederman 180143c97ccSLinus Torvalds struct pts_fs_info *devpts_acquire(struct file *filp) 18159e55e6cSSukadev Bhattiprolu { 182eedf265aSEric W. Biederman struct pts_fs_info *result; 183eedf265aSEric W. Biederman struct path path; 184eedf265aSEric W. Biederman struct super_block *sb; 185eedf265aSEric W. Biederman 186eedf265aSEric W. Biederman path = filp->f_path; 187eedf265aSEric W. Biederman path_get(&path); 188eedf265aSEric W. Biederman 1897d71109dSChristian Brauner /* Has the devpts filesystem already been found? */ 1907d71109dSChristian Brauner if (path.mnt->mnt_sb->s_magic != DEVPTS_SUPER_MAGIC) { 1917d71109dSChristian Brauner int err; 1927d71109dSChristian Brauner 193311fc65cSEric W. Biederman err = devpts_ptmx_path(&path); 194eedf265aSEric W. Biederman if (err) { 195eedf265aSEric W. Biederman result = ERR_PTR(err); 196eedf265aSEric W. Biederman goto out; 197eedf265aSEric W. Biederman } 1987d71109dSChristian Brauner } 199eedf265aSEric W. Biederman 200eedf265aSEric W. Biederman /* 201eedf265aSEric W. Biederman * pty code needs to hold extra references in case of last /dev/tty close 202eedf265aSEric W. Biederman */ 203311fc65cSEric W. Biederman sb = path.mnt->mnt_sb; 204eedf265aSEric W. Biederman atomic_inc(&sb->s_active); 205eedf265aSEric W. Biederman result = DEVPTS_SB(sb); 206eedf265aSEric W. Biederman 207eedf265aSEric W. Biederman out: 208eedf265aSEric W. Biederman path_put(&path); 209eedf265aSEric W. Biederman return result; 210eedf265aSEric W. Biederman } 211eedf265aSEric W. Biederman 212eedf265aSEric W. Biederman void devpts_release(struct pts_fs_info *fsi) 213eedf265aSEric W. Biederman { 214eedf265aSEric W. Biederman deactivate_super(fsi->sb); 21559e55e6cSSukadev Bhattiprolu } 21659e55e6cSSukadev Bhattiprolu 2172a1b2dc0SSukadev Bhattiprolu #define PARSE_MOUNT 0 2182a1b2dc0SSukadev Bhattiprolu #define PARSE_REMOUNT 1 2192a1b2dc0SSukadev Bhattiprolu 2201f71ebedSSukadev Bhattiprolu /* 2211f71ebedSSukadev Bhattiprolu * parse_mount_options(): 2221f71ebedSSukadev Bhattiprolu * Set @opts to mount options specified in @data. If an option is not 223eedf265aSEric W. Biederman * specified in @data, set it to its default value. 2241f71ebedSSukadev Bhattiprolu * 2251f71ebedSSukadev Bhattiprolu * Note: @data may be NULL (in which case all options are set to default). 2261f71ebedSSukadev Bhattiprolu */ 2272a1b2dc0SSukadev Bhattiprolu static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) 2281da177e4SLinus Torvalds { 2297a673c6bSDomen Puncer char *p; 230f04c6ce2SEric W. Biederman kuid_t uid; 231f04c6ce2SEric W. Biederman kgid_t gid; 2321da177e4SLinus Torvalds 23331af0abbSSukadev Bhattiprolu opts->setuid = 0; 23431af0abbSSukadev Bhattiprolu opts->setgid = 0; 235f04c6ce2SEric W. Biederman opts->uid = GLOBAL_ROOT_UID; 236f04c6ce2SEric W. Biederman opts->gid = GLOBAL_ROOT_GID; 23731af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 2381f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 239e9aba515SKonstantin Khlebnikov opts->max = NR_UNIX98_PTY_MAX; 2407a673c6bSDomen Puncer 241eedf265aSEric W. Biederman /* Only allow instances mounted from the initial mount 242eedf265aSEric W. Biederman * namespace to tap the reserve pool of ptys. 243eedf265aSEric W. Biederman */ 2442a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 245eedf265aSEric W. Biederman opts->reserve = 246eedf265aSEric W. Biederman (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); 2472a1b2dc0SSukadev Bhattiprolu 2487a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 2497a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 2507a673c6bSDomen Puncer int token; 2517a673c6bSDomen Puncer int option; 2527a673c6bSDomen Puncer 2537a673c6bSDomen Puncer if (!*p) 2541da177e4SLinus Torvalds continue; 2557a673c6bSDomen Puncer 2567a673c6bSDomen Puncer token = match_token(p, tokens, args); 2577a673c6bSDomen Puncer switch (token) { 2587a673c6bSDomen Puncer case Opt_uid: 2597a673c6bSDomen Puncer if (match_int(&args[0], &option)) 2607a673c6bSDomen Puncer return -EINVAL; 261f04c6ce2SEric W. Biederman uid = make_kuid(current_user_ns(), option); 262f04c6ce2SEric W. Biederman if (!uid_valid(uid)) 263f04c6ce2SEric W. Biederman return -EINVAL; 264f04c6ce2SEric W. Biederman opts->uid = uid; 26531af0abbSSukadev Bhattiprolu opts->setuid = 1; 2667a673c6bSDomen Puncer break; 2677a673c6bSDomen Puncer case Opt_gid: 2687a673c6bSDomen Puncer if (match_int(&args[0], &option)) 2697a673c6bSDomen Puncer return -EINVAL; 270f04c6ce2SEric W. Biederman gid = make_kgid(current_user_ns(), option); 271f04c6ce2SEric W. Biederman if (!gid_valid(gid)) 272f04c6ce2SEric W. Biederman return -EINVAL; 273f04c6ce2SEric W. Biederman opts->gid = gid; 27431af0abbSSukadev Bhattiprolu opts->setgid = 1; 2757a673c6bSDomen Puncer break; 2767a673c6bSDomen Puncer case Opt_mode: 2777a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 2787a673c6bSDomen Puncer return -EINVAL; 27931af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 2807a673c6bSDomen Puncer break; 2811f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 2821f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 2831f8f1e29SSukadev Bhattiprolu return -EINVAL; 2841f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 2851f8f1e29SSukadev Bhattiprolu break; 2862a1b2dc0SSukadev Bhattiprolu case Opt_newinstance: 2872a1b2dc0SSukadev Bhattiprolu break; 288e9aba515SKonstantin Khlebnikov case Opt_max: 289e9aba515SKonstantin Khlebnikov if (match_int(&args[0], &option) || 290e9aba515SKonstantin Khlebnikov option < 0 || option > NR_UNIX98_PTY_MAX) 291e9aba515SKonstantin Khlebnikov return -EINVAL; 292e9aba515SKonstantin Khlebnikov opts->max = option; 293e9aba515SKonstantin Khlebnikov break; 2947a673c6bSDomen Puncer default: 29504541a2fSFabian Frederick pr_err("called with bogus options\n"); 2961da177e4SLinus Torvalds return -EINVAL; 2971da177e4SLinus Torvalds } 2981da177e4SLinus Torvalds } 2991da177e4SLinus Torvalds 3001da177e4SLinus Torvalds return 0; 3011da177e4SLinus Torvalds } 3021da177e4SLinus Torvalds 3031f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 30453af8ee4SSukadev Bhattiprolu { 3051f8f1e29SSukadev Bhattiprolu int mode; 3061f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 3071f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 3081f8f1e29SSukadev Bhattiprolu struct inode *inode; 3091f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 31053af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 31153af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 312e98d4137SEric W. Biederman kuid_t ptmx_uid = current_fsuid(); 313e98d4137SEric W. Biederman kgid_t ptmx_gid = current_fsgid(); 31453af8ee4SSukadev Bhattiprolu 3155955102cSAl Viro inode_lock(d_inode(root)); 3161f8f1e29SSukadev Bhattiprolu 3171f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 3181f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 3191f8f1e29SSukadev Bhattiprolu rc = 0; 3201f8f1e29SSukadev Bhattiprolu goto out; 3211f8f1e29SSukadev Bhattiprolu } 3221f8f1e29SSukadev Bhattiprolu 3231f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 3241f8f1e29SSukadev Bhattiprolu if (!dentry) { 32504541a2fSFabian Frederick pr_err("Unable to alloc dentry for ptmx node\n"); 3261f8f1e29SSukadev Bhattiprolu goto out; 3271f8f1e29SSukadev Bhattiprolu } 3281f8f1e29SSukadev Bhattiprolu 3291f8f1e29SSukadev Bhattiprolu /* 3301f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 3311f8f1e29SSukadev Bhattiprolu */ 3321f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 3331f8f1e29SSukadev Bhattiprolu if (!inode) { 33404541a2fSFabian Frederick pr_err("Unable to alloc inode for ptmx node\n"); 3351f8f1e29SSukadev Bhattiprolu dput(dentry); 3361f8f1e29SSukadev Bhattiprolu goto out; 3371f8f1e29SSukadev Bhattiprolu } 3381f8f1e29SSukadev Bhattiprolu 3391f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 340078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 3411f8f1e29SSukadev Bhattiprolu 3421f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 3431f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 344e98d4137SEric W. Biederman inode->i_uid = ptmx_uid; 345e98d4137SEric W. Biederman inode->i_gid = ptmx_gid; 3461f8f1e29SSukadev Bhattiprolu 3471f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 3481f8f1e29SSukadev Bhattiprolu 3491f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 3501f8f1e29SSukadev Bhattiprolu rc = 0; 3511f8f1e29SSukadev Bhattiprolu out: 3525955102cSAl Viro inode_unlock(d_inode(root)); 3531f8f1e29SSukadev Bhattiprolu return rc; 3541f8f1e29SSukadev Bhattiprolu } 3551f8f1e29SSukadev Bhattiprolu 3561f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 3571f8f1e29SSukadev Bhattiprolu { 3581f8f1e29SSukadev Bhattiprolu struct inode *inode; 3591f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 3602b0143b5SDavid Howells inode = d_inode(fsi->ptmx_dentry); 3611f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 3621f8f1e29SSukadev Bhattiprolu } 3631f8f1e29SSukadev Bhattiprolu } 3641f8f1e29SSukadev Bhattiprolu 3651f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 3661f8f1e29SSukadev Bhattiprolu { 3671f8f1e29SSukadev Bhattiprolu int err; 3681f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 3691f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 3701f8f1e29SSukadev Bhattiprolu 3712a1b2dc0SSukadev Bhattiprolu err = parse_mount_options(data, PARSE_REMOUNT, opts); 3721f8f1e29SSukadev Bhattiprolu 3731f8f1e29SSukadev Bhattiprolu /* 3741f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 3751f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 3761f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 3771f8f1e29SSukadev Bhattiprolu * so do this even on error return. 3781f8f1e29SSukadev Bhattiprolu */ 3791f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 3801f8f1e29SSukadev Bhattiprolu 3811f8f1e29SSukadev Bhattiprolu return err; 38253af8ee4SSukadev Bhattiprolu } 38353af8ee4SSukadev Bhattiprolu 38434c80b1dSAl Viro static int devpts_show_options(struct seq_file *seq, struct dentry *root) 385b87a267eSMiklos Szeredi { 38634c80b1dSAl Viro struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); 38731af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 38831af0abbSSukadev Bhattiprolu 38931af0abbSSukadev Bhattiprolu if (opts->setuid) 39004541a2fSFabian Frederick seq_printf(seq, ",uid=%u", 39104541a2fSFabian Frederick from_kuid_munged(&init_user_ns, opts->uid)); 39231af0abbSSukadev Bhattiprolu if (opts->setgid) 39304541a2fSFabian Frederick seq_printf(seq, ",gid=%u", 39404541a2fSFabian Frederick from_kgid_munged(&init_user_ns, opts->gid)); 39531af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 3961f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 397e9aba515SKonstantin Khlebnikov if (opts->max < NR_UNIX98_PTY_MAX) 398e9aba515SKonstantin Khlebnikov seq_printf(seq, ",max=%d", opts->max); 399b87a267eSMiklos Szeredi 400b87a267eSMiklos Szeredi return 0; 401b87a267eSMiklos Szeredi } 402b87a267eSMiklos Szeredi 403ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 4041da177e4SLinus Torvalds .statfs = simple_statfs, 4051da177e4SLinus Torvalds .remount_fs = devpts_remount, 406b87a267eSMiklos Szeredi .show_options = devpts_show_options, 4071da177e4SLinus Torvalds }; 4081da177e4SLinus Torvalds 40967245ff3SLinus Torvalds static void *new_pts_fs_info(struct super_block *sb) 410e76b7c01SSukadev Bhattiprolu { 411e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 412e76b7c01SSukadev Bhattiprolu 413e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 414e76b7c01SSukadev Bhattiprolu if (!fsi) 415e76b7c01SSukadev Bhattiprolu return NULL; 416e76b7c01SSukadev Bhattiprolu 417e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 41831af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 4191f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 42067245ff3SLinus Torvalds fsi->sb = sb; 421e76b7c01SSukadev Bhattiprolu 422e76b7c01SSukadev Bhattiprolu return fsi; 423e76b7c01SSukadev Bhattiprolu } 424e76b7c01SSukadev Bhattiprolu 4251da177e4SLinus Torvalds static int 4261da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 4271da177e4SLinus Torvalds { 4281da177e4SLinus Torvalds struct inode *inode; 429dee87d47SEric W. Biederman int error; 4301da177e4SLinus Torvalds 431cc50a07aSEric W. Biederman s->s_iflags &= ~SB_I_NODEV; 4321da177e4SLinus Torvalds s->s_blocksize = 1024; 4331da177e4SLinus Torvalds s->s_blocksize_bits = 10; 4341da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 4351da177e4SLinus Torvalds s->s_op = &devpts_sops; 4361da177e4SLinus Torvalds s->s_time_gran = 1; 4371da177e4SLinus Torvalds 438dee87d47SEric W. Biederman error = -ENOMEM; 43967245ff3SLinus Torvalds s->s_fs_info = new_pts_fs_info(s); 440e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 441e76b7c01SSukadev Bhattiprolu goto fail; 442e76b7c01SSukadev Bhattiprolu 443dee87d47SEric W. Biederman error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts); 444dee87d47SEric W. Biederman if (error) 445dee87d47SEric W. Biederman goto fail; 446dee87d47SEric W. Biederman 447dee87d47SEric W. Biederman error = -ENOMEM; 4481da177e4SLinus Torvalds inode = new_inode(s); 4491da177e4SLinus Torvalds if (!inode) 4503850aba7SAl Viro goto fail; 4511da177e4SLinus Torvalds inode->i_ino = 1; 452078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 4531da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 4541da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 4551da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 456bfe86848SMiklos Szeredi set_nlink(inode, 2); 4571da177e4SLinus Torvalds 45848fde701SAl Viro s->s_root = d_make_root(inode); 459180d9044SEric W. Biederman if (!s->s_root) { 46004541a2fSFabian Frederick pr_err("get root dentry failed\n"); 461180d9044SEric W. Biederman goto fail; 462180d9044SEric W. Biederman } 463e76b7c01SSukadev Bhattiprolu 464180d9044SEric W. Biederman error = mknod_ptmx(s); 465180d9044SEric W. Biederman if (error) 466180d9044SEric W. Biederman goto fail_dput; 467180d9044SEric W. Biederman 468180d9044SEric W. Biederman return 0; 469180d9044SEric W. Biederman fail_dput: 470180d9044SEric W. Biederman dput(s->s_root); 471180d9044SEric W. Biederman s->s_root = NULL; 4721da177e4SLinus Torvalds fail: 473dee87d47SEric W. Biederman return error; 4741da177e4SLinus Torvalds } 4751da177e4SLinus Torvalds 4762a1b2dc0SSukadev Bhattiprolu /* 477fc14f2feSAl Viro * devpts_mount() 478289f00e2SSukadev Bhattiprolu * 479eedf265aSEric W. Biederman * Mount a new (private) instance of devpts. PTYs created in this 480eedf265aSEric W. Biederman * instance are independent of the PTYs in other devpts instances. 481d4076ac5SSukadev Bhattiprolu */ 482fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, 483fc14f2feSAl Viro int flags, const char *dev_name, void *data) 4841da177e4SLinus Torvalds { 485c1b241f0SEric W. Biederman return mount_nodev(fs_type, flags, data, devpts_fill_super); 486482984f0SSukadev Bhattiprolu } 487482984f0SSukadev Bhattiprolu 488e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 489e76b7c01SSukadev Bhattiprolu { 490e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 491e76b7c01SSukadev Bhattiprolu 49240b320e1SEric W. Biederman if (fsi) 49366da0e1fSIlija Hadzic ida_destroy(&fsi->allocated_ptys); 494e76b7c01SSukadev Bhattiprolu kfree(fsi); 4951f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 496e76b7c01SSukadev Bhattiprolu } 497e76b7c01SSukadev Bhattiprolu 4981da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 4991da177e4SLinus Torvalds .name = "devpts", 500fc14f2feSAl Viro .mount = devpts_mount, 501e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 502cc50a07aSEric W. Biederman .fs_flags = FS_USERNS_MOUNT, 5031da177e4SLinus Torvalds }; 5041da177e4SLinus Torvalds 5051da177e4SLinus Torvalds /* 5061da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 5071da177e4SLinus Torvalds * to the System V naming convention 5081da177e4SLinus Torvalds */ 5091da177e4SLinus Torvalds 51067245ff3SLinus Torvalds int devpts_new_index(struct pts_fs_info *fsi) 511718a9163SSukadev Bhattiprolu { 512718a9163SSukadev Bhattiprolu int index; 5137ee7c12bSAlexey Dobriyan int ida_ret; 514718a9163SSukadev Bhattiprolu 515718a9163SSukadev Bhattiprolu retry: 516835aa440SAlan Cox if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) 517718a9163SSukadev Bhattiprolu return -ENOMEM; 518718a9163SSukadev Bhattiprolu 519718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 520eedf265aSEric W. Biederman if (pty_count >= (pty_limit - 521eedf265aSEric W. Biederman (fsi->mount_opts.reserve ? 0 : pty_reserve))) { 522e9aba515SKonstantin Khlebnikov mutex_unlock(&allocated_ptys_lock); 523e9aba515SKonstantin Khlebnikov return -ENOSPC; 524e9aba515SKonstantin Khlebnikov } 525e9aba515SKonstantin Khlebnikov 526e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 5277ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 528718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 5297ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 530718a9163SSukadev Bhattiprolu goto retry; 531718a9163SSukadev Bhattiprolu return -EIO; 532718a9163SSukadev Bhattiprolu } 533718a9163SSukadev Bhattiprolu 534e9aba515SKonstantin Khlebnikov if (index >= fsi->mount_opts.max) { 535e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 536718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 537e9aba515SKonstantin Khlebnikov return -ENOSPC; 538718a9163SSukadev Bhattiprolu } 539a4834c10SKonstantin Khlebnikov pty_count++; 540718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 541718a9163SSukadev Bhattiprolu return index; 542718a9163SSukadev Bhattiprolu } 543718a9163SSukadev Bhattiprolu 54467245ff3SLinus Torvalds void devpts_kill_index(struct pts_fs_info *fsi, int idx) 545718a9163SSukadev Bhattiprolu { 546718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 547e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 548a4834c10SKonstantin Khlebnikov pty_count--; 549718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 550718a9163SSukadev Bhattiprolu } 551718a9163SSukadev Bhattiprolu 5521dcb8e6dSJiri Slaby /** 5531dcb8e6dSJiri Slaby * devpts_pty_new -- create a new inode in /dev/pts/ 5541dcb8e6dSJiri Slaby * @ptmx_inode: inode of the master 5551dcb8e6dSJiri Slaby * @device: major+minor of the node to be created 5561dcb8e6dSJiri Slaby * @index: used as a name of the node 5571dcb8e6dSJiri Slaby * @priv: what's given back by devpts_get_priv 5581dcb8e6dSJiri Slaby * 5591dcb8e6dSJiri Slaby * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill. 5601dcb8e6dSJiri Slaby */ 5618ead9dd5SLinus Torvalds struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) 5621da177e4SLinus Torvalds { 5631da177e4SLinus Torvalds struct dentry *dentry; 564eedf265aSEric W. Biederman struct super_block *sb = fsi->sb; 565162b97cfSJiri Slaby struct inode *inode; 5669ce71148SJosh Triplett struct dentry *root; 5679ce71148SJosh Triplett struct pts_mount_opts *opts; 56889a52e10SSukadev Bhattiprolu char s[12]; 5691da177e4SLinus Torvalds 5709ce71148SJosh Triplett root = sb->s_root; 5719ce71148SJosh Triplett opts = &fsi->mount_opts; 5729ce71148SJosh Triplett 573162b97cfSJiri Slaby inode = new_inode(sb); 5741da177e4SLinus Torvalds if (!inode) 575162b97cfSJiri Slaby return ERR_PTR(-ENOMEM); 5761da177e4SLinus Torvalds 577f11afb61SJiri Slaby inode->i_ino = index + 3; 578d0eafc7dSDavid Howells inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); 579d0eafc7dSDavid Howells inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); 580078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 5818ead9dd5SLinus Torvalds init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index)); 5821da177e4SLinus Torvalds 583f11afb61SJiri Slaby sprintf(s, "%d", index); 58489a52e10SSukadev Bhattiprolu 58559e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 586b12d1259SAndrey Vagin if (dentry) { 5878ead9dd5SLinus Torvalds dentry->d_fsdata = priv; 58889a52e10SSukadev Bhattiprolu d_add(dentry, inode); 5892b0143b5SDavid Howells fsnotify_create(d_inode(root), dentry); 590aa597bc1SAndrey Vagin } else { 591aa597bc1SAndrey Vagin iput(inode); 5928ead9dd5SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 5933972b7f6SFlorin Malita } 5941da177e4SLinus Torvalds 5958ead9dd5SLinus Torvalds return dentry; 5961da177e4SLinus Torvalds } 5971da177e4SLinus Torvalds 5981dcb8e6dSJiri Slaby /** 5991dcb8e6dSJiri Slaby * devpts_get_priv -- get private data for a slave 6001dcb8e6dSJiri Slaby * @pts_inode: inode of the slave 6011dcb8e6dSJiri Slaby * 6021dcb8e6dSJiri Slaby * Returns whatever was passed as priv in devpts_pty_new for a given inode. 6031dcb8e6dSJiri Slaby */ 6048ead9dd5SLinus Torvalds void *devpts_get_priv(struct dentry *dentry) 6051da177e4SLinus Torvalds { 6063e423945SLinus Torvalds if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC) 6073e423945SLinus Torvalds return NULL; 6088ead9dd5SLinus Torvalds return dentry->d_fsdata; 6091da177e4SLinus Torvalds } 6101da177e4SLinus Torvalds 6111dcb8e6dSJiri Slaby /** 6121dcb8e6dSJiri Slaby * devpts_pty_kill -- remove inode form /dev/pts/ 6131dcb8e6dSJiri Slaby * @inode: inode of the slave to be removed 6141dcb8e6dSJiri Slaby * 6151dcb8e6dSJiri Slaby * This is an inverse operation of devpts_pty_new. 6161dcb8e6dSJiri Slaby */ 6178ead9dd5SLinus Torvalds void devpts_pty_kill(struct dentry *dentry) 6181da177e4SLinus Torvalds { 6198ead9dd5SLinus Torvalds WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC); 6201da177e4SLinus Torvalds 6218ead9dd5SLinus Torvalds dentry->d_fsdata = NULL; 6228ead9dd5SLinus Torvalds drop_nlink(dentry->d_inode); 6231da177e4SLinus Torvalds d_delete(dentry); 624835aa440SAlan Cox dput(dentry); /* d_alloc_name() in devpts_pty_new() */ 6251da177e4SLinus Torvalds } 6261da177e4SLinus Torvalds 6271da177e4SLinus Torvalds static int __init init_devpts_fs(void) 6281da177e4SLinus Torvalds { 6291da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 6301da177e4SLinus Torvalds if (!err) { 631eedf265aSEric W. Biederman register_sysctl_table(pty_root_table); 6321da177e4SLinus Torvalds } 6331da177e4SLinus Torvalds return err; 6341da177e4SLinus Torvalds } 6351da177e4SLinus Torvalds module_init(init_devpts_fs) 636