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 /* Has the devpts filesystem already been found? */ 142311fc65cSEric W. Biederman if (path->mnt->mnt_sb->s_magic == DEVPTS_SUPER_MAGIC) 143311fc65cSEric W. Biederman return 0; 144311fc65cSEric W. Biederman 145311fc65cSEric W. Biederman /* Is a devpts filesystem at "pts" in the same directory? */ 146311fc65cSEric W. Biederman err = path_pts(path); 147311fc65cSEric W. Biederman if (err) 148311fc65cSEric W. Biederman return err; 149311fc65cSEric W. Biederman 150311fc65cSEric W. Biederman /* Is the path the root of a devpts filesystem? */ 151311fc65cSEric W. Biederman sb = path->mnt->mnt_sb; 152311fc65cSEric W. Biederman if ((sb->s_magic != DEVPTS_SUPER_MAGIC) || 153311fc65cSEric W. Biederman (path->mnt->mnt_root != sb->s_root)) 154311fc65cSEric W. Biederman return -ENODEV; 155311fc65cSEric W. Biederman 156311fc65cSEric W. Biederman return 0; 157311fc65cSEric W. Biederman } 158311fc65cSEric W. Biederman 159311fc65cSEric W. Biederman struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) 160311fc65cSEric W. Biederman { 161311fc65cSEric W. Biederman struct path path; 162311fc65cSEric W. Biederman int err; 163311fc65cSEric W. Biederman 164311fc65cSEric W. Biederman path = filp->f_path; 165311fc65cSEric W. Biederman path_get(&path); 166311fc65cSEric W. Biederman 167311fc65cSEric W. Biederman err = devpts_ptmx_path(&path); 168311fc65cSEric W. Biederman dput(path.dentry); 169311fc65cSEric W. Biederman if (err) { 170311fc65cSEric W. Biederman mntput(path.mnt); 171311fc65cSEric W. Biederman path.mnt = ERR_PTR(err); 172311fc65cSEric W. Biederman } 173311fc65cSEric W. Biederman if (DEVPTS_SB(path.mnt->mnt_sb) != fsi) { 174311fc65cSEric W. Biederman mntput(path.mnt); 175311fc65cSEric W. Biederman path.mnt = ERR_PTR(-ENODEV); 176311fc65cSEric W. Biederman } 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 int err; 186eedf265aSEric W. Biederman 187eedf265aSEric W. Biederman path = filp->f_path; 188eedf265aSEric W. Biederman path_get(&path); 189eedf265aSEric W. Biederman 190311fc65cSEric W. Biederman err = devpts_ptmx_path(&path); 191eedf265aSEric W. Biederman if (err) { 192eedf265aSEric W. Biederman result = ERR_PTR(err); 193eedf265aSEric W. Biederman goto out; 194eedf265aSEric W. Biederman } 195eedf265aSEric W. Biederman 196eedf265aSEric W. Biederman /* 197eedf265aSEric W. Biederman * pty code needs to hold extra references in case of last /dev/tty close 198eedf265aSEric W. Biederman */ 199311fc65cSEric W. Biederman sb = path.mnt->mnt_sb; 200eedf265aSEric W. Biederman atomic_inc(&sb->s_active); 201eedf265aSEric W. Biederman result = DEVPTS_SB(sb); 202eedf265aSEric W. Biederman 203eedf265aSEric W. Biederman out: 204eedf265aSEric W. Biederman path_put(&path); 205eedf265aSEric W. Biederman return result; 206eedf265aSEric W. Biederman } 207eedf265aSEric W. Biederman 208eedf265aSEric W. Biederman void devpts_release(struct pts_fs_info *fsi) 209eedf265aSEric W. Biederman { 210eedf265aSEric W. Biederman deactivate_super(fsi->sb); 21159e55e6cSSukadev Bhattiprolu } 21259e55e6cSSukadev Bhattiprolu 2132a1b2dc0SSukadev Bhattiprolu #define PARSE_MOUNT 0 2142a1b2dc0SSukadev Bhattiprolu #define PARSE_REMOUNT 1 2152a1b2dc0SSukadev Bhattiprolu 2161f71ebedSSukadev Bhattiprolu /* 2171f71ebedSSukadev Bhattiprolu * parse_mount_options(): 2181f71ebedSSukadev Bhattiprolu * Set @opts to mount options specified in @data. If an option is not 219eedf265aSEric W. Biederman * specified in @data, set it to its default value. 2201f71ebedSSukadev Bhattiprolu * 2211f71ebedSSukadev Bhattiprolu * Note: @data may be NULL (in which case all options are set to default). 2221f71ebedSSukadev Bhattiprolu */ 2232a1b2dc0SSukadev Bhattiprolu static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) 2241da177e4SLinus Torvalds { 2257a673c6bSDomen Puncer char *p; 226f04c6ce2SEric W. Biederman kuid_t uid; 227f04c6ce2SEric W. Biederman kgid_t gid; 2281da177e4SLinus Torvalds 22931af0abbSSukadev Bhattiprolu opts->setuid = 0; 23031af0abbSSukadev Bhattiprolu opts->setgid = 0; 231f04c6ce2SEric W. Biederman opts->uid = GLOBAL_ROOT_UID; 232f04c6ce2SEric W. Biederman opts->gid = GLOBAL_ROOT_GID; 23331af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 2341f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 235e9aba515SKonstantin Khlebnikov opts->max = NR_UNIX98_PTY_MAX; 2367a673c6bSDomen Puncer 237eedf265aSEric W. Biederman /* Only allow instances mounted from the initial mount 238eedf265aSEric W. Biederman * namespace to tap the reserve pool of ptys. 239eedf265aSEric W. Biederman */ 2402a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 241eedf265aSEric W. Biederman opts->reserve = 242eedf265aSEric W. Biederman (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); 2432a1b2dc0SSukadev Bhattiprolu 2447a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 2457a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 2467a673c6bSDomen Puncer int token; 2477a673c6bSDomen Puncer int option; 2487a673c6bSDomen Puncer 2497a673c6bSDomen Puncer if (!*p) 2501da177e4SLinus Torvalds continue; 2517a673c6bSDomen Puncer 2527a673c6bSDomen Puncer token = match_token(p, tokens, args); 2537a673c6bSDomen Puncer switch (token) { 2547a673c6bSDomen Puncer case Opt_uid: 2557a673c6bSDomen Puncer if (match_int(&args[0], &option)) 2567a673c6bSDomen Puncer return -EINVAL; 257f04c6ce2SEric W. Biederman uid = make_kuid(current_user_ns(), option); 258f04c6ce2SEric W. Biederman if (!uid_valid(uid)) 259f04c6ce2SEric W. Biederman return -EINVAL; 260f04c6ce2SEric W. Biederman opts->uid = uid; 26131af0abbSSukadev Bhattiprolu opts->setuid = 1; 2627a673c6bSDomen Puncer break; 2637a673c6bSDomen Puncer case Opt_gid: 2647a673c6bSDomen Puncer if (match_int(&args[0], &option)) 2657a673c6bSDomen Puncer return -EINVAL; 266f04c6ce2SEric W. Biederman gid = make_kgid(current_user_ns(), option); 267f04c6ce2SEric W. Biederman if (!gid_valid(gid)) 268f04c6ce2SEric W. Biederman return -EINVAL; 269f04c6ce2SEric W. Biederman opts->gid = gid; 27031af0abbSSukadev Bhattiprolu opts->setgid = 1; 2717a673c6bSDomen Puncer break; 2727a673c6bSDomen Puncer case Opt_mode: 2737a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 2747a673c6bSDomen Puncer return -EINVAL; 27531af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 2767a673c6bSDomen Puncer break; 2771f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 2781f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 2791f8f1e29SSukadev Bhattiprolu return -EINVAL; 2801f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 2811f8f1e29SSukadev Bhattiprolu break; 2822a1b2dc0SSukadev Bhattiprolu case Opt_newinstance: 2832a1b2dc0SSukadev Bhattiprolu break; 284e9aba515SKonstantin Khlebnikov case Opt_max: 285e9aba515SKonstantin Khlebnikov if (match_int(&args[0], &option) || 286e9aba515SKonstantin Khlebnikov option < 0 || option > NR_UNIX98_PTY_MAX) 287e9aba515SKonstantin Khlebnikov return -EINVAL; 288e9aba515SKonstantin Khlebnikov opts->max = option; 289e9aba515SKonstantin Khlebnikov break; 2907a673c6bSDomen Puncer default: 29104541a2fSFabian Frederick pr_err("called with bogus options\n"); 2921da177e4SLinus Torvalds return -EINVAL; 2931da177e4SLinus Torvalds } 2941da177e4SLinus Torvalds } 2951da177e4SLinus Torvalds 2961da177e4SLinus Torvalds return 0; 2971da177e4SLinus Torvalds } 2981da177e4SLinus Torvalds 2991f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 30053af8ee4SSukadev Bhattiprolu { 3011f8f1e29SSukadev Bhattiprolu int mode; 3021f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 3031f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 3041f8f1e29SSukadev Bhattiprolu struct inode *inode; 3051f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 30653af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 30753af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 308e98d4137SEric W. Biederman kuid_t ptmx_uid = current_fsuid(); 309e98d4137SEric W. Biederman kgid_t ptmx_gid = current_fsgid(); 31053af8ee4SSukadev Bhattiprolu 3115955102cSAl Viro inode_lock(d_inode(root)); 3121f8f1e29SSukadev Bhattiprolu 3131f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 3141f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 3151f8f1e29SSukadev Bhattiprolu rc = 0; 3161f8f1e29SSukadev Bhattiprolu goto out; 3171f8f1e29SSukadev Bhattiprolu } 3181f8f1e29SSukadev Bhattiprolu 3191f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 3201f8f1e29SSukadev Bhattiprolu if (!dentry) { 32104541a2fSFabian Frederick pr_err("Unable to alloc dentry for ptmx node\n"); 3221f8f1e29SSukadev Bhattiprolu goto out; 3231f8f1e29SSukadev Bhattiprolu } 3241f8f1e29SSukadev Bhattiprolu 3251f8f1e29SSukadev Bhattiprolu /* 3261f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 3271f8f1e29SSukadev Bhattiprolu */ 3281f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 3291f8f1e29SSukadev Bhattiprolu if (!inode) { 33004541a2fSFabian Frederick pr_err("Unable to alloc inode for ptmx node\n"); 3311f8f1e29SSukadev Bhattiprolu dput(dentry); 3321f8f1e29SSukadev Bhattiprolu goto out; 3331f8f1e29SSukadev Bhattiprolu } 3341f8f1e29SSukadev Bhattiprolu 3351f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 336078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 3371f8f1e29SSukadev Bhattiprolu 3381f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 3391f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 340e98d4137SEric W. Biederman inode->i_uid = ptmx_uid; 341e98d4137SEric W. Biederman inode->i_gid = ptmx_gid; 3421f8f1e29SSukadev Bhattiprolu 3431f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 3441f8f1e29SSukadev Bhattiprolu 3451f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 3461f8f1e29SSukadev Bhattiprolu rc = 0; 3471f8f1e29SSukadev Bhattiprolu out: 3485955102cSAl Viro inode_unlock(d_inode(root)); 3491f8f1e29SSukadev Bhattiprolu return rc; 3501f8f1e29SSukadev Bhattiprolu } 3511f8f1e29SSukadev Bhattiprolu 3521f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 3531f8f1e29SSukadev Bhattiprolu { 3541f8f1e29SSukadev Bhattiprolu struct inode *inode; 3551f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 3562b0143b5SDavid Howells inode = d_inode(fsi->ptmx_dentry); 3571f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 3581f8f1e29SSukadev Bhattiprolu } 3591f8f1e29SSukadev Bhattiprolu } 3601f8f1e29SSukadev Bhattiprolu 3611f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 3621f8f1e29SSukadev Bhattiprolu { 3631f8f1e29SSukadev Bhattiprolu int err; 3641f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 3651f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 3661f8f1e29SSukadev Bhattiprolu 3672a1b2dc0SSukadev Bhattiprolu err = parse_mount_options(data, PARSE_REMOUNT, opts); 3681f8f1e29SSukadev Bhattiprolu 3691f8f1e29SSukadev Bhattiprolu /* 3701f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 3711f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 3721f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 3731f8f1e29SSukadev Bhattiprolu * so do this even on error return. 3741f8f1e29SSukadev Bhattiprolu */ 3751f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 3761f8f1e29SSukadev Bhattiprolu 3771f8f1e29SSukadev Bhattiprolu return err; 37853af8ee4SSukadev Bhattiprolu } 37953af8ee4SSukadev Bhattiprolu 38034c80b1dSAl Viro static int devpts_show_options(struct seq_file *seq, struct dentry *root) 381b87a267eSMiklos Szeredi { 38234c80b1dSAl Viro struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); 38331af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 38431af0abbSSukadev Bhattiprolu 38531af0abbSSukadev Bhattiprolu if (opts->setuid) 38604541a2fSFabian Frederick seq_printf(seq, ",uid=%u", 38704541a2fSFabian Frederick from_kuid_munged(&init_user_ns, opts->uid)); 38831af0abbSSukadev Bhattiprolu if (opts->setgid) 38904541a2fSFabian Frederick seq_printf(seq, ",gid=%u", 39004541a2fSFabian Frederick from_kgid_munged(&init_user_ns, opts->gid)); 39131af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 3921f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 393e9aba515SKonstantin Khlebnikov if (opts->max < NR_UNIX98_PTY_MAX) 394e9aba515SKonstantin Khlebnikov seq_printf(seq, ",max=%d", opts->max); 395b87a267eSMiklos Szeredi 396b87a267eSMiklos Szeredi return 0; 397b87a267eSMiklos Szeredi } 398b87a267eSMiklos Szeredi 399ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 4001da177e4SLinus Torvalds .statfs = simple_statfs, 4011da177e4SLinus Torvalds .remount_fs = devpts_remount, 402b87a267eSMiklos Szeredi .show_options = devpts_show_options, 4031da177e4SLinus Torvalds }; 4041da177e4SLinus Torvalds 40567245ff3SLinus Torvalds static void *new_pts_fs_info(struct super_block *sb) 406e76b7c01SSukadev Bhattiprolu { 407e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 408e76b7c01SSukadev Bhattiprolu 409e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 410e76b7c01SSukadev Bhattiprolu if (!fsi) 411e76b7c01SSukadev Bhattiprolu return NULL; 412e76b7c01SSukadev Bhattiprolu 413e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 41431af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 4151f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 41667245ff3SLinus Torvalds fsi->sb = sb; 417e76b7c01SSukadev Bhattiprolu 418e76b7c01SSukadev Bhattiprolu return fsi; 419e76b7c01SSukadev Bhattiprolu } 420e76b7c01SSukadev Bhattiprolu 4211da177e4SLinus Torvalds static int 4221da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 4231da177e4SLinus Torvalds { 4241da177e4SLinus Torvalds struct inode *inode; 425dee87d47SEric W. Biederman int error; 4261da177e4SLinus Torvalds 427cc50a07aSEric W. Biederman s->s_iflags &= ~SB_I_NODEV; 4281da177e4SLinus Torvalds s->s_blocksize = 1024; 4291da177e4SLinus Torvalds s->s_blocksize_bits = 10; 4301da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 4311da177e4SLinus Torvalds s->s_op = &devpts_sops; 4321da177e4SLinus Torvalds s->s_time_gran = 1; 4331da177e4SLinus Torvalds 434dee87d47SEric W. Biederman error = -ENOMEM; 43567245ff3SLinus Torvalds s->s_fs_info = new_pts_fs_info(s); 436e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 437e76b7c01SSukadev Bhattiprolu goto fail; 438e76b7c01SSukadev Bhattiprolu 439dee87d47SEric W. Biederman error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts); 440dee87d47SEric W. Biederman if (error) 441dee87d47SEric W. Biederman goto fail; 442dee87d47SEric W. Biederman 443dee87d47SEric W. Biederman error = -ENOMEM; 4441da177e4SLinus Torvalds inode = new_inode(s); 4451da177e4SLinus Torvalds if (!inode) 4463850aba7SAl Viro goto fail; 4471da177e4SLinus Torvalds inode->i_ino = 1; 448078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 4491da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 4501da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 4511da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 452bfe86848SMiklos Szeredi set_nlink(inode, 2); 4531da177e4SLinus Torvalds 45448fde701SAl Viro s->s_root = d_make_root(inode); 455180d9044SEric W. Biederman if (!s->s_root) { 45604541a2fSFabian Frederick pr_err("get root dentry failed\n"); 457180d9044SEric W. Biederman goto fail; 458180d9044SEric W. Biederman } 459e76b7c01SSukadev Bhattiprolu 460180d9044SEric W. Biederman error = mknod_ptmx(s); 461180d9044SEric W. Biederman if (error) 462180d9044SEric W. Biederman goto fail_dput; 463180d9044SEric W. Biederman 464180d9044SEric W. Biederman return 0; 465180d9044SEric W. Biederman fail_dput: 466180d9044SEric W. Biederman dput(s->s_root); 467180d9044SEric W. Biederman s->s_root = NULL; 4681da177e4SLinus Torvalds fail: 469dee87d47SEric W. Biederman return error; 4701da177e4SLinus Torvalds } 4711da177e4SLinus Torvalds 4722a1b2dc0SSukadev Bhattiprolu /* 473fc14f2feSAl Viro * devpts_mount() 474289f00e2SSukadev Bhattiprolu * 475eedf265aSEric W. Biederman * Mount a new (private) instance of devpts. PTYs created in this 476eedf265aSEric W. Biederman * instance are independent of the PTYs in other devpts instances. 477d4076ac5SSukadev Bhattiprolu */ 478fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, 479fc14f2feSAl Viro int flags, const char *dev_name, void *data) 4801da177e4SLinus Torvalds { 481c1b241f0SEric W. Biederman return mount_nodev(fs_type, flags, data, devpts_fill_super); 482482984f0SSukadev Bhattiprolu } 483482984f0SSukadev Bhattiprolu 484e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 485e76b7c01SSukadev Bhattiprolu { 486e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 487e76b7c01SSukadev Bhattiprolu 48840b320e1SEric W. Biederman if (fsi) 48966da0e1fSIlija Hadzic ida_destroy(&fsi->allocated_ptys); 490e76b7c01SSukadev Bhattiprolu kfree(fsi); 4911f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 492e76b7c01SSukadev Bhattiprolu } 493e76b7c01SSukadev Bhattiprolu 4941da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 4951da177e4SLinus Torvalds .name = "devpts", 496fc14f2feSAl Viro .mount = devpts_mount, 497e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 498cc50a07aSEric W. Biederman .fs_flags = FS_USERNS_MOUNT, 4991da177e4SLinus Torvalds }; 5001da177e4SLinus Torvalds 5011da177e4SLinus Torvalds /* 5021da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 5031da177e4SLinus Torvalds * to the System V naming convention 5041da177e4SLinus Torvalds */ 5051da177e4SLinus Torvalds 50667245ff3SLinus Torvalds int devpts_new_index(struct pts_fs_info *fsi) 507718a9163SSukadev Bhattiprolu { 508718a9163SSukadev Bhattiprolu int index; 5097ee7c12bSAlexey Dobriyan int ida_ret; 510718a9163SSukadev Bhattiprolu 511718a9163SSukadev Bhattiprolu retry: 512835aa440SAlan Cox if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) 513718a9163SSukadev Bhattiprolu return -ENOMEM; 514718a9163SSukadev Bhattiprolu 515718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 516eedf265aSEric W. Biederman if (pty_count >= (pty_limit - 517eedf265aSEric W. Biederman (fsi->mount_opts.reserve ? 0 : pty_reserve))) { 518e9aba515SKonstantin Khlebnikov mutex_unlock(&allocated_ptys_lock); 519e9aba515SKonstantin Khlebnikov return -ENOSPC; 520e9aba515SKonstantin Khlebnikov } 521e9aba515SKonstantin Khlebnikov 522e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 5237ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 524718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 5257ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 526718a9163SSukadev Bhattiprolu goto retry; 527718a9163SSukadev Bhattiprolu return -EIO; 528718a9163SSukadev Bhattiprolu } 529718a9163SSukadev Bhattiprolu 530e9aba515SKonstantin Khlebnikov if (index >= fsi->mount_opts.max) { 531e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 532718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 533e9aba515SKonstantin Khlebnikov return -ENOSPC; 534718a9163SSukadev Bhattiprolu } 535a4834c10SKonstantin Khlebnikov pty_count++; 536718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 537718a9163SSukadev Bhattiprolu return index; 538718a9163SSukadev Bhattiprolu } 539718a9163SSukadev Bhattiprolu 54067245ff3SLinus Torvalds void devpts_kill_index(struct pts_fs_info *fsi, int idx) 541718a9163SSukadev Bhattiprolu { 542718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 543e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 544a4834c10SKonstantin Khlebnikov pty_count--; 545718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 546718a9163SSukadev Bhattiprolu } 547718a9163SSukadev Bhattiprolu 5481dcb8e6dSJiri Slaby /** 5491dcb8e6dSJiri Slaby * devpts_pty_new -- create a new inode in /dev/pts/ 5501dcb8e6dSJiri Slaby * @ptmx_inode: inode of the master 5511dcb8e6dSJiri Slaby * @device: major+minor of the node to be created 5521dcb8e6dSJiri Slaby * @index: used as a name of the node 5531dcb8e6dSJiri Slaby * @priv: what's given back by devpts_get_priv 5541dcb8e6dSJiri Slaby * 5551dcb8e6dSJiri Slaby * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill. 5561dcb8e6dSJiri Slaby */ 5578ead9dd5SLinus Torvalds struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) 5581da177e4SLinus Torvalds { 5591da177e4SLinus Torvalds struct dentry *dentry; 560eedf265aSEric W. Biederman struct super_block *sb = fsi->sb; 561162b97cfSJiri Slaby struct inode *inode; 5629ce71148SJosh Triplett struct dentry *root; 5639ce71148SJosh Triplett struct pts_mount_opts *opts; 56489a52e10SSukadev Bhattiprolu char s[12]; 5651da177e4SLinus Torvalds 5669ce71148SJosh Triplett root = sb->s_root; 5679ce71148SJosh Triplett opts = &fsi->mount_opts; 5689ce71148SJosh Triplett 569162b97cfSJiri Slaby inode = new_inode(sb); 5701da177e4SLinus Torvalds if (!inode) 571162b97cfSJiri Slaby return ERR_PTR(-ENOMEM); 5721da177e4SLinus Torvalds 573f11afb61SJiri Slaby inode->i_ino = index + 3; 574d0eafc7dSDavid Howells inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); 575d0eafc7dSDavid Howells inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); 576078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 5778ead9dd5SLinus Torvalds init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index)); 5781da177e4SLinus Torvalds 579f11afb61SJiri Slaby sprintf(s, "%d", index); 58089a52e10SSukadev Bhattiprolu 58159e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 582b12d1259SAndrey Vagin if (dentry) { 5838ead9dd5SLinus Torvalds dentry->d_fsdata = priv; 58489a52e10SSukadev Bhattiprolu d_add(dentry, inode); 5852b0143b5SDavid Howells fsnotify_create(d_inode(root), dentry); 586aa597bc1SAndrey Vagin } else { 587aa597bc1SAndrey Vagin iput(inode); 5888ead9dd5SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 5893972b7f6SFlorin Malita } 5901da177e4SLinus Torvalds 5918ead9dd5SLinus Torvalds return dentry; 5921da177e4SLinus Torvalds } 5931da177e4SLinus Torvalds 5941dcb8e6dSJiri Slaby /** 5951dcb8e6dSJiri Slaby * devpts_get_priv -- get private data for a slave 5961dcb8e6dSJiri Slaby * @pts_inode: inode of the slave 5971dcb8e6dSJiri Slaby * 5981dcb8e6dSJiri Slaby * Returns whatever was passed as priv in devpts_pty_new for a given inode. 5991dcb8e6dSJiri Slaby */ 6008ead9dd5SLinus Torvalds void *devpts_get_priv(struct dentry *dentry) 6011da177e4SLinus Torvalds { 6023e423945SLinus Torvalds if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC) 6033e423945SLinus Torvalds return NULL; 6048ead9dd5SLinus Torvalds return dentry->d_fsdata; 6051da177e4SLinus Torvalds } 6061da177e4SLinus Torvalds 6071dcb8e6dSJiri Slaby /** 6081dcb8e6dSJiri Slaby * devpts_pty_kill -- remove inode form /dev/pts/ 6091dcb8e6dSJiri Slaby * @inode: inode of the slave to be removed 6101dcb8e6dSJiri Slaby * 6111dcb8e6dSJiri Slaby * This is an inverse operation of devpts_pty_new. 6121dcb8e6dSJiri Slaby */ 6138ead9dd5SLinus Torvalds void devpts_pty_kill(struct dentry *dentry) 6141da177e4SLinus Torvalds { 6158ead9dd5SLinus Torvalds WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC); 6161da177e4SLinus Torvalds 6178ead9dd5SLinus Torvalds dentry->d_fsdata = NULL; 6188ead9dd5SLinus Torvalds drop_nlink(dentry->d_inode); 6191da177e4SLinus Torvalds d_delete(dentry); 620835aa440SAlan Cox dput(dentry); /* d_alloc_name() in devpts_pty_new() */ 6211da177e4SLinus Torvalds } 6221da177e4SLinus Torvalds 6231da177e4SLinus Torvalds static int __init init_devpts_fs(void) 6241da177e4SLinus Torvalds { 6251da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 6261da177e4SLinus Torvalds if (!err) { 627eedf265aSEric W. Biederman register_sysctl_table(pty_root_table); 6281da177e4SLinus Torvalds } 6291da177e4SLinus Torvalds return err; 6301da177e4SLinus Torvalds } 6311da177e4SLinus Torvalds module_init(init_devpts_fs) 632