11da177e4SLinus Torvalds /* -*- linux-c -*- --------------------------------------------------------- * 21da177e4SLinus Torvalds * 31da177e4SLinus Torvalds * linux/fs/devpts/inode.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * This file is part of the Linux kernel and is made available under 81da177e4SLinus Torvalds * the terms of the GNU General Public License, version 2, or at your 91da177e4SLinus Torvalds * option, any later version, incorporated herein by reference. 101da177e4SLinus Torvalds * 111da177e4SLinus Torvalds * ------------------------------------------------------------------------- */ 121da177e4SLinus Torvalds 131da177e4SLinus Torvalds #include <linux/module.h> 141da177e4SLinus Torvalds #include <linux/init.h> 151da177e4SLinus Torvalds #include <linux/fs.h> 161da177e4SLinus Torvalds #include <linux/sched.h> 171da177e4SLinus Torvalds #include <linux/namei.h> 185a0e3ad6STejun Heo #include <linux/slab.h> 191da177e4SLinus Torvalds #include <linux/mount.h> 201da177e4SLinus Torvalds #include <linux/tty.h> 21718a9163SSukadev Bhattiprolu #include <linux/mutex.h> 221fd7317dSNick Black #include <linux/magic.h> 23718a9163SSukadev Bhattiprolu #include <linux/idr.h> 241da177e4SLinus Torvalds #include <linux/devpts_fs.h> 257a673c6bSDomen Puncer #include <linux/parser.h> 263972b7f6SFlorin Malita #include <linux/fsnotify.h> 27b87a267eSMiklos Szeredi #include <linux/seq_file.h> 281da177e4SLinus Torvalds 29b87a267eSMiklos Szeredi #define DEVPTS_DEFAULT_MODE 0600 301f8f1e29SSukadev Bhattiprolu /* 311f8f1e29SSukadev Bhattiprolu * ptmx is a new node in /dev/pts and will be unused in legacy (single- 321f8f1e29SSukadev Bhattiprolu * instance) mode. To prevent surprises in user space, set permissions of 331f8f1e29SSukadev Bhattiprolu * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful 341f8f1e29SSukadev Bhattiprolu * permissions. 351f8f1e29SSukadev Bhattiprolu */ 361f8f1e29SSukadev Bhattiprolu #define DEVPTS_DEFAULT_PTMX_MODE 0000 37527b3e47SSukadev Bhattiprolu #define PTMX_MINOR 2 38b87a267eSMiklos Szeredi 39a4834c10SKonstantin Khlebnikov /* 40a4834c10SKonstantin Khlebnikov * sysctl support for setting limits on the number of Unix98 ptys allocated. 41a4834c10SKonstantin Khlebnikov * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly. 42a4834c10SKonstantin Khlebnikov */ 43a4834c10SKonstantin Khlebnikov static int pty_limit = NR_UNIX98_PTY_DEFAULT; 44e9aba515SKonstantin Khlebnikov static int pty_reserve = NR_UNIX98_PTY_RESERVE; 45a4834c10SKonstantin Khlebnikov static int pty_limit_min; 46e9aba515SKonstantin Khlebnikov static int pty_limit_max = INT_MAX; 47a4834c10SKonstantin Khlebnikov static int pty_count; 48a4834c10SKonstantin Khlebnikov 49a4834c10SKonstantin Khlebnikov static struct ctl_table pty_table[] = { 50a4834c10SKonstantin Khlebnikov { 51a4834c10SKonstantin Khlebnikov .procname = "max", 52a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 53a4834c10SKonstantin Khlebnikov .mode = 0644, 54a4834c10SKonstantin Khlebnikov .data = &pty_limit, 55a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec_minmax, 56a4834c10SKonstantin Khlebnikov .extra1 = &pty_limit_min, 57a4834c10SKonstantin Khlebnikov .extra2 = &pty_limit_max, 58a4834c10SKonstantin Khlebnikov }, { 59e9aba515SKonstantin Khlebnikov .procname = "reserve", 60e9aba515SKonstantin Khlebnikov .maxlen = sizeof(int), 61e9aba515SKonstantin Khlebnikov .mode = 0644, 62e9aba515SKonstantin Khlebnikov .data = &pty_reserve, 63e9aba515SKonstantin Khlebnikov .proc_handler = proc_dointvec_minmax, 64e9aba515SKonstantin Khlebnikov .extra1 = &pty_limit_min, 65e9aba515SKonstantin Khlebnikov .extra2 = &pty_limit_max, 66e9aba515SKonstantin Khlebnikov }, { 67a4834c10SKonstantin Khlebnikov .procname = "nr", 68a4834c10SKonstantin Khlebnikov .maxlen = sizeof(int), 69a4834c10SKonstantin Khlebnikov .mode = 0444, 70a4834c10SKonstantin Khlebnikov .data = &pty_count, 71a4834c10SKonstantin Khlebnikov .proc_handler = proc_dointvec, 72a4834c10SKonstantin Khlebnikov }, 73a4834c10SKonstantin Khlebnikov {} 74a4834c10SKonstantin Khlebnikov }; 75a4834c10SKonstantin Khlebnikov 76a4834c10SKonstantin Khlebnikov static struct ctl_table pty_kern_table[] = { 77a4834c10SKonstantin Khlebnikov { 78a4834c10SKonstantin Khlebnikov .procname = "pty", 79a4834c10SKonstantin Khlebnikov .mode = 0555, 80a4834c10SKonstantin Khlebnikov .child = pty_table, 81a4834c10SKonstantin Khlebnikov }, 82a4834c10SKonstantin Khlebnikov {} 83a4834c10SKonstantin Khlebnikov }; 84a4834c10SKonstantin Khlebnikov 85a4834c10SKonstantin Khlebnikov static struct ctl_table pty_root_table[] = { 86a4834c10SKonstantin Khlebnikov { 87a4834c10SKonstantin Khlebnikov .procname = "kernel", 88a4834c10SKonstantin Khlebnikov .mode = 0555, 89a4834c10SKonstantin Khlebnikov .child = pty_kern_table, 90a4834c10SKonstantin Khlebnikov }, 91a4834c10SKonstantin Khlebnikov {} 92a4834c10SKonstantin Khlebnikov }; 93a4834c10SKonstantin Khlebnikov 94718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 95718a9163SSukadev Bhattiprolu 961da177e4SLinus Torvalds static struct vfsmount *devpts_mnt; 971da177e4SLinus Torvalds 9831af0abbSSukadev Bhattiprolu struct pts_mount_opts { 991da177e4SLinus Torvalds int setuid; 1001da177e4SLinus Torvalds int setgid; 101f04c6ce2SEric W. Biederman kuid_t uid; 102f04c6ce2SEric W. Biederman kgid_t gid; 1031da177e4SLinus Torvalds umode_t mode; 1041f8f1e29SSukadev Bhattiprolu umode_t ptmxmode; 1052a1b2dc0SSukadev Bhattiprolu int newinstance; 106e9aba515SKonstantin Khlebnikov int max; 10731af0abbSSukadev Bhattiprolu }; 1081da177e4SLinus Torvalds 1097a673c6bSDomen Puncer enum { 110e9aba515SKonstantin Khlebnikov Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max, 1117a673c6bSDomen Puncer Opt_err 1127a673c6bSDomen Puncer }; 1137a673c6bSDomen Puncer 114a447c093SSteven Whitehouse static const match_table_t tokens = { 1157a673c6bSDomen Puncer {Opt_uid, "uid=%u"}, 1167a673c6bSDomen Puncer {Opt_gid, "gid=%u"}, 1177a673c6bSDomen Puncer {Opt_mode, "mode=%o"}, 1181f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1191f8f1e29SSukadev Bhattiprolu {Opt_ptmxmode, "ptmxmode=%o"}, 1202a1b2dc0SSukadev Bhattiprolu {Opt_newinstance, "newinstance"}, 121e9aba515SKonstantin Khlebnikov {Opt_max, "max=%d"}, 1221f8f1e29SSukadev Bhattiprolu #endif 1237a673c6bSDomen Puncer {Opt_err, NULL} 1247a673c6bSDomen Puncer }; 1257a673c6bSDomen Puncer 126e76b7c01SSukadev Bhattiprolu struct pts_fs_info { 127e76b7c01SSukadev Bhattiprolu struct ida allocated_ptys; 12831af0abbSSukadev Bhattiprolu struct pts_mount_opts mount_opts; 1291f8f1e29SSukadev Bhattiprolu struct dentry *ptmx_dentry; 130e76b7c01SSukadev Bhattiprolu }; 131e76b7c01SSukadev Bhattiprolu 132e76b7c01SSukadev Bhattiprolu static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) 133e76b7c01SSukadev Bhattiprolu { 134e76b7c01SSukadev Bhattiprolu return sb->s_fs_info; 135e76b7c01SSukadev Bhattiprolu } 136e76b7c01SSukadev Bhattiprolu 13759e55e6cSSukadev Bhattiprolu static inline struct super_block *pts_sb_from_inode(struct inode *inode) 13859e55e6cSSukadev Bhattiprolu { 1392a1b2dc0SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 14059e55e6cSSukadev Bhattiprolu if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 14159e55e6cSSukadev Bhattiprolu return inode->i_sb; 1422a1b2dc0SSukadev Bhattiprolu #endif 14359e55e6cSSukadev Bhattiprolu return devpts_mnt->mnt_sb; 14459e55e6cSSukadev Bhattiprolu } 14559e55e6cSSukadev Bhattiprolu 1462a1b2dc0SSukadev Bhattiprolu #define PARSE_MOUNT 0 1472a1b2dc0SSukadev Bhattiprolu #define PARSE_REMOUNT 1 1482a1b2dc0SSukadev Bhattiprolu 1491f71ebedSSukadev Bhattiprolu /* 1501f71ebedSSukadev Bhattiprolu * parse_mount_options(): 1511f71ebedSSukadev Bhattiprolu * Set @opts to mount options specified in @data. If an option is not 1521f71ebedSSukadev Bhattiprolu * specified in @data, set it to its default value. The exception is 1531f71ebedSSukadev Bhattiprolu * 'newinstance' option which can only be set/cleared on a mount (i.e. 1541f71ebedSSukadev Bhattiprolu * cannot be changed during remount). 1551f71ebedSSukadev Bhattiprolu * 1561f71ebedSSukadev Bhattiprolu * Note: @data may be NULL (in which case all options are set to default). 1571f71ebedSSukadev Bhattiprolu */ 1582a1b2dc0SSukadev Bhattiprolu static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) 1591da177e4SLinus Torvalds { 1607a673c6bSDomen Puncer char *p; 161f04c6ce2SEric W. Biederman kuid_t uid; 162f04c6ce2SEric W. Biederman kgid_t gid; 1631da177e4SLinus Torvalds 16431af0abbSSukadev Bhattiprolu opts->setuid = 0; 16531af0abbSSukadev Bhattiprolu opts->setgid = 0; 166f04c6ce2SEric W. Biederman opts->uid = GLOBAL_ROOT_UID; 167f04c6ce2SEric W. Biederman opts->gid = GLOBAL_ROOT_GID; 16831af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 1691f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 170e9aba515SKonstantin Khlebnikov opts->max = NR_UNIX98_PTY_MAX; 1717a673c6bSDomen Puncer 1722a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 1732a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 1742a1b2dc0SSukadev Bhattiprolu opts->newinstance = 0; 1752a1b2dc0SSukadev Bhattiprolu 1767a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 1777a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 1787a673c6bSDomen Puncer int token; 1797a673c6bSDomen Puncer int option; 1807a673c6bSDomen Puncer 1817a673c6bSDomen Puncer if (!*p) 1821da177e4SLinus Torvalds continue; 1837a673c6bSDomen Puncer 1847a673c6bSDomen Puncer token = match_token(p, tokens, args); 1857a673c6bSDomen Puncer switch (token) { 1867a673c6bSDomen Puncer case Opt_uid: 1877a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1887a673c6bSDomen Puncer return -EINVAL; 189f04c6ce2SEric W. Biederman uid = make_kuid(current_user_ns(), option); 190f04c6ce2SEric W. Biederman if (!uid_valid(uid)) 191f04c6ce2SEric W. Biederman return -EINVAL; 192f04c6ce2SEric W. Biederman opts->uid = uid; 19331af0abbSSukadev Bhattiprolu opts->setuid = 1; 1947a673c6bSDomen Puncer break; 1957a673c6bSDomen Puncer case Opt_gid: 1967a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1977a673c6bSDomen Puncer return -EINVAL; 198f04c6ce2SEric W. Biederman gid = make_kgid(current_user_ns(), option); 199f04c6ce2SEric W. Biederman if (!gid_valid(gid)) 200f04c6ce2SEric W. Biederman return -EINVAL; 201f04c6ce2SEric W. Biederman opts->gid = gid; 20231af0abbSSukadev Bhattiprolu opts->setgid = 1; 2037a673c6bSDomen Puncer break; 2047a673c6bSDomen Puncer case Opt_mode: 2057a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 2067a673c6bSDomen Puncer return -EINVAL; 20731af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 2087a673c6bSDomen Puncer break; 2091f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 2101f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 2111f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 2121f8f1e29SSukadev Bhattiprolu return -EINVAL; 2131f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 2141f8f1e29SSukadev Bhattiprolu break; 2152a1b2dc0SSukadev Bhattiprolu case Opt_newinstance: 2162a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 2172a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 2182a1b2dc0SSukadev Bhattiprolu opts->newinstance = 1; 2192a1b2dc0SSukadev Bhattiprolu break; 220e9aba515SKonstantin Khlebnikov case Opt_max: 221e9aba515SKonstantin Khlebnikov if (match_int(&args[0], &option) || 222e9aba515SKonstantin Khlebnikov option < 0 || option > NR_UNIX98_PTY_MAX) 223e9aba515SKonstantin Khlebnikov return -EINVAL; 224e9aba515SKonstantin Khlebnikov opts->max = option; 225e9aba515SKonstantin Khlebnikov break; 2261f8f1e29SSukadev Bhattiprolu #endif 2277a673c6bSDomen Puncer default: 2287a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 2291da177e4SLinus Torvalds return -EINVAL; 2301da177e4SLinus Torvalds } 2311da177e4SLinus Torvalds } 2321da177e4SLinus Torvalds 2331da177e4SLinus Torvalds return 0; 2341da177e4SLinus Torvalds } 2351da177e4SLinus Torvalds 2361f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 2371f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 23853af8ee4SSukadev Bhattiprolu { 2391f8f1e29SSukadev Bhattiprolu int mode; 2401f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 2411f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 2421f8f1e29SSukadev Bhattiprolu struct inode *inode; 2431f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 24453af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 24553af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 24653af8ee4SSukadev Bhattiprolu 2471f8f1e29SSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 2481f8f1e29SSukadev Bhattiprolu 2491f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 2501f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2511f8f1e29SSukadev Bhattiprolu rc = 0; 2521f8f1e29SSukadev Bhattiprolu goto out; 2531f8f1e29SSukadev Bhattiprolu } 2541f8f1e29SSukadev Bhattiprolu 2551f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 2561f8f1e29SSukadev Bhattiprolu if (!dentry) { 2571f8f1e29SSukadev Bhattiprolu printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n"); 2581f8f1e29SSukadev Bhattiprolu goto out; 2591f8f1e29SSukadev Bhattiprolu } 2601f8f1e29SSukadev Bhattiprolu 2611f8f1e29SSukadev Bhattiprolu /* 2621f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 2631f8f1e29SSukadev Bhattiprolu */ 2641f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 2651f8f1e29SSukadev Bhattiprolu if (!inode) { 2661f8f1e29SSukadev Bhattiprolu printk(KERN_ERR "Unable to alloc inode for ptmx node\n"); 2671f8f1e29SSukadev Bhattiprolu dput(dentry); 2681f8f1e29SSukadev Bhattiprolu goto out; 2691f8f1e29SSukadev Bhattiprolu } 2701f8f1e29SSukadev Bhattiprolu 2711f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 2721f8f1e29SSukadev Bhattiprolu inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 2731f8f1e29SSukadev Bhattiprolu 2741f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 2751f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 2761f8f1e29SSukadev Bhattiprolu 2771f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 2781f8f1e29SSukadev Bhattiprolu 2791f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 2801f8f1e29SSukadev Bhattiprolu rc = 0; 2811f8f1e29SSukadev Bhattiprolu out: 2821f8f1e29SSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 2831f8f1e29SSukadev Bhattiprolu return rc; 2841f8f1e29SSukadev Bhattiprolu } 2851f8f1e29SSukadev Bhattiprolu 2861f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 2871f8f1e29SSukadev Bhattiprolu { 2881f8f1e29SSukadev Bhattiprolu struct inode *inode; 2891f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2901f8f1e29SSukadev Bhattiprolu inode = fsi->ptmx_dentry->d_inode; 2911f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 2921f8f1e29SSukadev Bhattiprolu } 2931f8f1e29SSukadev Bhattiprolu } 2941f8f1e29SSukadev Bhattiprolu #else 2951f8f1e29SSukadev Bhattiprolu static inline void update_ptmx_mode(struct pts_fs_info *fsi) 2961f8f1e29SSukadev Bhattiprolu { 2971f8f1e29SSukadev Bhattiprolu return; 2981f8f1e29SSukadev Bhattiprolu } 2991f8f1e29SSukadev Bhattiprolu #endif 3001f8f1e29SSukadev Bhattiprolu 3011f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 3021f8f1e29SSukadev Bhattiprolu { 3031f8f1e29SSukadev Bhattiprolu int err; 3041f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 3051f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 3061f8f1e29SSukadev Bhattiprolu 3072a1b2dc0SSukadev Bhattiprolu err = parse_mount_options(data, PARSE_REMOUNT, opts); 3081f8f1e29SSukadev Bhattiprolu 3091f8f1e29SSukadev Bhattiprolu /* 3101f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 3111f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 3121f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 3131f8f1e29SSukadev Bhattiprolu * so do this even on error return. 3141f8f1e29SSukadev Bhattiprolu */ 3151f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 3161f8f1e29SSukadev Bhattiprolu 3171f8f1e29SSukadev Bhattiprolu return err; 31853af8ee4SSukadev Bhattiprolu } 31953af8ee4SSukadev Bhattiprolu 32034c80b1dSAl Viro static int devpts_show_options(struct seq_file *seq, struct dentry *root) 321b87a267eSMiklos Szeredi { 32234c80b1dSAl Viro struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); 32331af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 32431af0abbSSukadev Bhattiprolu 32531af0abbSSukadev Bhattiprolu if (opts->setuid) 326f04c6ce2SEric W. Biederman seq_printf(seq, ",uid=%u", from_kuid_munged(&init_user_ns, opts->uid)); 32731af0abbSSukadev Bhattiprolu if (opts->setgid) 328f04c6ce2SEric W. Biederman seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, opts->gid)); 32931af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 3301f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 3311f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 332e9aba515SKonstantin Khlebnikov if (opts->max < NR_UNIX98_PTY_MAX) 333e9aba515SKonstantin Khlebnikov seq_printf(seq, ",max=%d", opts->max); 3341f8f1e29SSukadev Bhattiprolu #endif 335b87a267eSMiklos Szeredi 336b87a267eSMiklos Szeredi return 0; 337b87a267eSMiklos Szeredi } 338b87a267eSMiklos Szeredi 339ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 3401da177e4SLinus Torvalds .statfs = simple_statfs, 3411da177e4SLinus Torvalds .remount_fs = devpts_remount, 342b87a267eSMiklos Szeredi .show_options = devpts_show_options, 3431da177e4SLinus Torvalds }; 3441da177e4SLinus Torvalds 345e76b7c01SSukadev Bhattiprolu static void *new_pts_fs_info(void) 346e76b7c01SSukadev Bhattiprolu { 347e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 348e76b7c01SSukadev Bhattiprolu 349e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 350e76b7c01SSukadev Bhattiprolu if (!fsi) 351e76b7c01SSukadev Bhattiprolu return NULL; 352e76b7c01SSukadev Bhattiprolu 353e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 35431af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 3551f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 356e76b7c01SSukadev Bhattiprolu 357e76b7c01SSukadev Bhattiprolu return fsi; 358e76b7c01SSukadev Bhattiprolu } 359e76b7c01SSukadev Bhattiprolu 3601da177e4SLinus Torvalds static int 3611da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 3621da177e4SLinus Torvalds { 3631da177e4SLinus Torvalds struct inode *inode; 3641da177e4SLinus Torvalds 3651da177e4SLinus Torvalds s->s_blocksize = 1024; 3661da177e4SLinus Torvalds s->s_blocksize_bits = 10; 3671da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 3681da177e4SLinus Torvalds s->s_op = &devpts_sops; 3691da177e4SLinus Torvalds s->s_time_gran = 1; 3701da177e4SLinus Torvalds 371e76b7c01SSukadev Bhattiprolu s->s_fs_info = new_pts_fs_info(); 372e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 373e76b7c01SSukadev Bhattiprolu goto fail; 374e76b7c01SSukadev Bhattiprolu 3751da177e4SLinus Torvalds inode = new_inode(s); 3761da177e4SLinus Torvalds if (!inode) 3773850aba7SAl Viro goto fail; 3781da177e4SLinus Torvalds inode->i_ino = 1; 3791da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 3801da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 3811da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 3821da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 383bfe86848SMiklos Szeredi set_nlink(inode, 2); 3841da177e4SLinus Torvalds 38548fde701SAl Viro s->s_root = d_make_root(inode); 3861da177e4SLinus Torvalds if (s->s_root) 3871da177e4SLinus Torvalds return 0; 3881da177e4SLinus Torvalds 389835aa440SAlan Cox printk(KERN_ERR "devpts: get root dentry failed\n"); 390e76b7c01SSukadev Bhattiprolu 3911da177e4SLinus Torvalds fail: 3921da177e4SLinus Torvalds return -ENOMEM; 3931da177e4SLinus Torvalds } 3941da177e4SLinus Torvalds 3958c056e5bSAndrew Morton #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 396d4076ac5SSukadev Bhattiprolu static int compare_init_pts_sb(struct super_block *s, void *p) 397d4076ac5SSukadev Bhattiprolu { 398d4076ac5SSukadev Bhattiprolu if (devpts_mnt) 399d4076ac5SSukadev Bhattiprolu return devpts_mnt->mnt_sb == s; 4002a1b2dc0SSukadev Bhattiprolu return 0; 4012a1b2dc0SSukadev Bhattiprolu } 4022a1b2dc0SSukadev Bhattiprolu 4032a1b2dc0SSukadev Bhattiprolu /* 404fc14f2feSAl Viro * devpts_mount() 405289f00e2SSukadev Bhattiprolu * 4061bd79035SSukadev Bhattiprolu * If the '-o newinstance' mount option was specified, mount a new 4071bd79035SSukadev Bhattiprolu * (private) instance of devpts. PTYs created in this instance are 4081bd79035SSukadev Bhattiprolu * independent of the PTYs in other devpts instances. 409d4076ac5SSukadev Bhattiprolu * 4101bd79035SSukadev Bhattiprolu * If the '-o newinstance' option was not specified, mount/remount the 4111bd79035SSukadev Bhattiprolu * initial kernel mount of devpts. This type of mount gives the 4121bd79035SSukadev Bhattiprolu * legacy, single-instance semantics. 413d4076ac5SSukadev Bhattiprolu * 4141bd79035SSukadev Bhattiprolu * The 'newinstance' option is needed to support multiple namespace 4151bd79035SSukadev Bhattiprolu * semantics in devpts while preserving backward compatibility of the 4161bd79035SSukadev Bhattiprolu * current 'single-namespace' semantics. i.e all mounts of devpts 4171bd79035SSukadev Bhattiprolu * without the 'newinstance' mount option should bind to the initial 418fc14f2feSAl Viro * kernel mount, like mount_single(). 419d4076ac5SSukadev Bhattiprolu * 4201bd79035SSukadev Bhattiprolu * Mounts with 'newinstance' option create a new, private namespace. 4211bd79035SSukadev Bhattiprolu * 4221bd79035SSukadev Bhattiprolu * NOTE: 4231bd79035SSukadev Bhattiprolu * 424fc14f2feSAl Viro * For single-mount semantics, devpts cannot use mount_single(), 425fc14f2feSAl Viro * because mount_single()/sget() find and use the super-block from 426d4076ac5SSukadev Bhattiprolu * the most recent mount of devpts. But that recent mount may be a 427fc14f2feSAl Viro * 'newinstance' mount and mount_single() would pick the newinstance 428d4076ac5SSukadev Bhattiprolu * super-block instead of the initial super-block. 429d4076ac5SSukadev Bhattiprolu */ 430fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, 431fc14f2feSAl Viro int flags, const char *dev_name, void *data) 4321da177e4SLinus Torvalds { 433482984f0SSukadev Bhattiprolu int error; 434482984f0SSukadev Bhattiprolu struct pts_mount_opts opts; 4351bd79035SSukadev Bhattiprolu struct super_block *s; 4362a1b2dc0SSukadev Bhattiprolu 437482984f0SSukadev Bhattiprolu error = parse_mount_options(data, PARSE_MOUNT, &opts); 438482984f0SSukadev Bhattiprolu if (error) 439fc14f2feSAl Viro return ERR_PTR(error); 440482984f0SSukadev Bhattiprolu 441482984f0SSukadev Bhattiprolu if (opts.newinstance) 4429249e17fSDavid Howells s = sget(fs_type, NULL, set_anon_super, flags, NULL); 443482984f0SSukadev Bhattiprolu else 4449249e17fSDavid Howells s = sget(fs_type, compare_init_pts_sb, set_anon_super, flags, 4459249e17fSDavid Howells NULL); 446945cf2c7SSukadev Bhattiprolu 4471bd79035SSukadev Bhattiprolu if (IS_ERR(s)) 448fc14f2feSAl Viro return ERR_CAST(s); 4491bd79035SSukadev Bhattiprolu 4501bd79035SSukadev Bhattiprolu if (!s->s_root) { 4511bd79035SSukadev Bhattiprolu error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0); 452945cf2c7SSukadev Bhattiprolu if (error) 4531bd79035SSukadev Bhattiprolu goto out_undo_sget; 4541bd79035SSukadev Bhattiprolu s->s_flags |= MS_ACTIVE; 4551bd79035SSukadev Bhattiprolu } 456945cf2c7SSukadev Bhattiprolu 4571bd79035SSukadev Bhattiprolu memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts)); 4581bd79035SSukadev Bhattiprolu 4591bd79035SSukadev Bhattiprolu error = mknod_ptmx(s); 460945cf2c7SSukadev Bhattiprolu if (error) 46189468071SAl Viro goto out_undo_sget; 46289468071SAl Viro 463fc14f2feSAl Viro return dget(s->s_root); 464945cf2c7SSukadev Bhattiprolu 4651bd79035SSukadev Bhattiprolu out_undo_sget: 4666f5bbff9SAl Viro deactivate_locked_super(s); 467fc14f2feSAl Viro return ERR_PTR(error); 468482984f0SSukadev Bhattiprolu } 469482984f0SSukadev Bhattiprolu 4702a1b2dc0SSukadev Bhattiprolu #else 4712a1b2dc0SSukadev Bhattiprolu /* 4722a1b2dc0SSukadev Bhattiprolu * This supports only the legacy single-instance semantics (no 4732a1b2dc0SSukadev Bhattiprolu * multiple-instance semantics) 4742a1b2dc0SSukadev Bhattiprolu */ 475fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, int flags, 476fc14f2feSAl Viro const char *dev_name, void *data) 4772a1b2dc0SSukadev Bhattiprolu { 478fc14f2feSAl Viro return mount_single(fs_type, flags, data, devpts_fill_super); 4792a1b2dc0SSukadev Bhattiprolu } 4802a1b2dc0SSukadev Bhattiprolu #endif 4811da177e4SLinus Torvalds 482e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 483e76b7c01SSukadev Bhattiprolu { 484e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 485e76b7c01SSukadev Bhattiprolu 486e76b7c01SSukadev Bhattiprolu kfree(fsi); 4871f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 488e76b7c01SSukadev Bhattiprolu } 489e76b7c01SSukadev Bhattiprolu 4901da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 4911da177e4SLinus Torvalds .name = "devpts", 492fc14f2feSAl Viro .mount = devpts_mount, 493e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 4941da177e4SLinus Torvalds }; 4951da177e4SLinus Torvalds 4961da177e4SLinus Torvalds /* 4971da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 4981da177e4SLinus Torvalds * to the System V naming convention 4991da177e4SLinus Torvalds */ 5001da177e4SLinus Torvalds 50115f1a633SSukadev Bhattiprolu int devpts_new_index(struct inode *ptmx_inode) 502718a9163SSukadev Bhattiprolu { 503e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 504e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 505718a9163SSukadev Bhattiprolu int index; 5067ee7c12bSAlexey Dobriyan int ida_ret; 507718a9163SSukadev Bhattiprolu 508718a9163SSukadev Bhattiprolu retry: 509835aa440SAlan Cox if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) 510718a9163SSukadev Bhattiprolu return -ENOMEM; 511718a9163SSukadev Bhattiprolu 512718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 513e9aba515SKonstantin Khlebnikov if (pty_count >= pty_limit - 514e9aba515SKonstantin Khlebnikov (fsi->mount_opts.newinstance ? pty_reserve : 0)) { 515e9aba515SKonstantin Khlebnikov mutex_unlock(&allocated_ptys_lock); 516e9aba515SKonstantin Khlebnikov return -ENOSPC; 517e9aba515SKonstantin Khlebnikov } 518e9aba515SKonstantin Khlebnikov 519e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 5207ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 521718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 5227ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 523718a9163SSukadev Bhattiprolu goto retry; 524718a9163SSukadev Bhattiprolu return -EIO; 525718a9163SSukadev Bhattiprolu } 526718a9163SSukadev Bhattiprolu 527e9aba515SKonstantin Khlebnikov if (index >= fsi->mount_opts.max) { 528e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 529718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 530e9aba515SKonstantin Khlebnikov return -ENOSPC; 531718a9163SSukadev Bhattiprolu } 532a4834c10SKonstantin Khlebnikov pty_count++; 533718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 534718a9163SSukadev Bhattiprolu return index; 535718a9163SSukadev Bhattiprolu } 536718a9163SSukadev Bhattiprolu 53715f1a633SSukadev Bhattiprolu void devpts_kill_index(struct inode *ptmx_inode, int idx) 538718a9163SSukadev Bhattiprolu { 539e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 540e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 541e76b7c01SSukadev 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 548162b97cfSJiri Slaby struct inode *devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) 5491da177e4SLinus Torvalds { 550835aa440SAlan Cox /* tty layer puts index from devpts_new_index() in here */ 551835aa440SAlan Cox int number = tty->index; 5521da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 5531da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 5541da177e4SLinus Torvalds struct dentry *dentry; 55559e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 556162b97cfSJiri Slaby struct inode *inode; 55759e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 55831af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 55931af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 56089a52e10SSukadev Bhattiprolu char s[12]; 5611da177e4SLinus Torvalds 5621da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 5631da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 5641da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 5651da177e4SLinus Torvalds 566162b97cfSJiri Slaby inode = new_inode(sb); 5671da177e4SLinus Torvalds if (!inode) 568162b97cfSJiri Slaby return ERR_PTR(-ENOMEM); 5691da177e4SLinus Torvalds 570d0eafc7dSDavid Howells inode->i_ino = number + 3; 571d0eafc7dSDavid Howells inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); 572d0eafc7dSDavid Howells inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); 5731da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 57431af0abbSSukadev Bhattiprolu init_special_inode(inode, S_IFCHR|opts->mode, device); 5758e18e294STheodore Ts'o inode->i_private = tty; 576a6f37daaSSukadev Bhattiprolu tty->driver_data = inode; 5771da177e4SLinus Torvalds 57889a52e10SSukadev Bhattiprolu sprintf(s, "%d", number); 57989a52e10SSukadev Bhattiprolu 58059e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 58189a52e10SSukadev Bhattiprolu 58259e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 583b12d1259SAndrey Vagin if (dentry) { 58489a52e10SSukadev Bhattiprolu d_add(dentry, inode); 58559e55e6cSSukadev Bhattiprolu fsnotify_create(root->d_inode, dentry); 586aa597bc1SAndrey Vagin } else { 587aa597bc1SAndrey Vagin iput(inode); 588162b97cfSJiri Slaby inode = ERR_PTR(-ENOMEM); 5893972b7f6SFlorin Malita } 5901da177e4SLinus Torvalds 59159e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 5921da177e4SLinus Torvalds 593162b97cfSJiri Slaby return inode; 5941da177e4SLinus Torvalds } 5951da177e4SLinus Torvalds 5968fcbaa2bSJiri Slaby void *devpts_get_priv(struct inode *pts_inode) 5971da177e4SLinus Torvalds { 598edfacdd6SSukadev Bhattiprolu struct dentry *dentry; 5998fcbaa2bSJiri Slaby void *priv = NULL; 600edfacdd6SSukadev Bhattiprolu 601527b3e47SSukadev Bhattiprolu BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 6021da177e4SLinus Torvalds 603edfacdd6SSukadev Bhattiprolu /* Ensure dentry has not been deleted by devpts_pty_kill() */ 604edfacdd6SSukadev Bhattiprolu dentry = d_find_alias(pts_inode); 605edfacdd6SSukadev Bhattiprolu if (!dentry) 606527b3e47SSukadev Bhattiprolu return NULL; 607edfacdd6SSukadev Bhattiprolu 608edfacdd6SSukadev Bhattiprolu if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 6098fcbaa2bSJiri Slaby priv = pts_inode->i_private; 610edfacdd6SSukadev Bhattiprolu 611edfacdd6SSukadev Bhattiprolu dput(dentry); 612edfacdd6SSukadev Bhattiprolu 6138fcbaa2bSJiri Slaby return priv; 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds 61615f1a633SSukadev Bhattiprolu void devpts_pty_kill(struct tty_struct *tty) 6171da177e4SLinus Torvalds { 618a6f37daaSSukadev Bhattiprolu struct inode *inode = tty->driver_data; 61959e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(inode); 62059e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 621a6f37daaSSukadev Bhattiprolu struct dentry *dentry; 6221da177e4SLinus Torvalds 623a6f37daaSSukadev Bhattiprolu BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 624a6f37daaSSukadev Bhattiprolu 62559e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 626a6f37daaSSukadev Bhattiprolu 627a6f37daaSSukadev Bhattiprolu dentry = d_find_alias(inode); 6282a1b2dc0SSukadev Bhattiprolu 6296d6b77f1SMiklos Szeredi drop_nlink(inode); 6301da177e4SLinus Torvalds d_delete(dentry); 631835aa440SAlan Cox dput(dentry); /* d_alloc_name() in devpts_pty_new() */ 632835aa440SAlan Cox dput(dentry); /* d_find_alias above */ 633aa597bc1SAndrey Vagin 63459e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 6351da177e4SLinus Torvalds } 6361da177e4SLinus Torvalds 6371da177e4SLinus Torvalds static int __init init_devpts_fs(void) 6381da177e4SLinus Torvalds { 6391da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 640a4834c10SKonstantin Khlebnikov struct ctl_table_header *table; 641a4834c10SKonstantin Khlebnikov 6421da177e4SLinus Torvalds if (!err) { 643a4834c10SKonstantin Khlebnikov table = register_sysctl_table(pty_root_table); 6441da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 64593d5581eSAlan Cox if (IS_ERR(devpts_mnt)) { 6461da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 64793d5581eSAlan Cox unregister_filesystem(&devpts_fs_type); 648a4834c10SKonstantin Khlebnikov unregister_sysctl_table(table); 64993d5581eSAlan Cox } 6501da177e4SLinus Torvalds } 6511da177e4SLinus Torvalds return err; 6521da177e4SLinus Torvalds } 6531da177e4SLinus Torvalds module_init(init_devpts_fs) 654