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 39718a9163SSukadev Bhattiprolu extern int pty_limit; /* Config limit on Unix98 ptys */ 40718a9163SSukadev Bhattiprolu static DEFINE_MUTEX(allocated_ptys_lock); 41718a9163SSukadev Bhattiprolu 421da177e4SLinus Torvalds static struct vfsmount *devpts_mnt; 431da177e4SLinus Torvalds 4431af0abbSSukadev Bhattiprolu struct pts_mount_opts { 451da177e4SLinus Torvalds int setuid; 461da177e4SLinus Torvalds int setgid; 471da177e4SLinus Torvalds uid_t uid; 481da177e4SLinus Torvalds gid_t gid; 491da177e4SLinus Torvalds umode_t mode; 501f8f1e29SSukadev Bhattiprolu umode_t ptmxmode; 512a1b2dc0SSukadev Bhattiprolu int newinstance; 5231af0abbSSukadev Bhattiprolu }; 531da177e4SLinus Torvalds 547a673c6bSDomen Puncer enum { 552a1b2dc0SSukadev Bhattiprolu Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, 567a673c6bSDomen Puncer Opt_err 577a673c6bSDomen Puncer }; 587a673c6bSDomen Puncer 59a447c093SSteven Whitehouse static const match_table_t tokens = { 607a673c6bSDomen Puncer {Opt_uid, "uid=%u"}, 617a673c6bSDomen Puncer {Opt_gid, "gid=%u"}, 627a673c6bSDomen Puncer {Opt_mode, "mode=%o"}, 631f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 641f8f1e29SSukadev Bhattiprolu {Opt_ptmxmode, "ptmxmode=%o"}, 652a1b2dc0SSukadev Bhattiprolu {Opt_newinstance, "newinstance"}, 661f8f1e29SSukadev Bhattiprolu #endif 677a673c6bSDomen Puncer {Opt_err, NULL} 687a673c6bSDomen Puncer }; 697a673c6bSDomen Puncer 70e76b7c01SSukadev Bhattiprolu struct pts_fs_info { 71e76b7c01SSukadev Bhattiprolu struct ida allocated_ptys; 7231af0abbSSukadev Bhattiprolu struct pts_mount_opts mount_opts; 731f8f1e29SSukadev Bhattiprolu struct dentry *ptmx_dentry; 74e76b7c01SSukadev Bhattiprolu }; 75e76b7c01SSukadev Bhattiprolu 76e76b7c01SSukadev Bhattiprolu static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb) 77e76b7c01SSukadev Bhattiprolu { 78e76b7c01SSukadev Bhattiprolu return sb->s_fs_info; 79e76b7c01SSukadev Bhattiprolu } 80e76b7c01SSukadev Bhattiprolu 8159e55e6cSSukadev Bhattiprolu static inline struct super_block *pts_sb_from_inode(struct inode *inode) 8259e55e6cSSukadev Bhattiprolu { 832a1b2dc0SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 8459e55e6cSSukadev Bhattiprolu if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 8559e55e6cSSukadev Bhattiprolu return inode->i_sb; 862a1b2dc0SSukadev Bhattiprolu #endif 8759e55e6cSSukadev Bhattiprolu return devpts_mnt->mnt_sb; 8859e55e6cSSukadev Bhattiprolu } 8959e55e6cSSukadev Bhattiprolu 902a1b2dc0SSukadev Bhattiprolu #define PARSE_MOUNT 0 912a1b2dc0SSukadev Bhattiprolu #define PARSE_REMOUNT 1 922a1b2dc0SSukadev Bhattiprolu 931f71ebedSSukadev Bhattiprolu /* 941f71ebedSSukadev Bhattiprolu * parse_mount_options(): 951f71ebedSSukadev Bhattiprolu * Set @opts to mount options specified in @data. If an option is not 961f71ebedSSukadev Bhattiprolu * specified in @data, set it to its default value. The exception is 971f71ebedSSukadev Bhattiprolu * 'newinstance' option which can only be set/cleared on a mount (i.e. 981f71ebedSSukadev Bhattiprolu * cannot be changed during remount). 991f71ebedSSukadev Bhattiprolu * 1001f71ebedSSukadev Bhattiprolu * Note: @data may be NULL (in which case all options are set to default). 1011f71ebedSSukadev Bhattiprolu */ 1022a1b2dc0SSukadev Bhattiprolu static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) 1031da177e4SLinus Torvalds { 1047a673c6bSDomen Puncer char *p; 1051da177e4SLinus Torvalds 10631af0abbSSukadev Bhattiprolu opts->setuid = 0; 10731af0abbSSukadev Bhattiprolu opts->setgid = 0; 10831af0abbSSukadev Bhattiprolu opts->uid = 0; 10931af0abbSSukadev Bhattiprolu opts->gid = 0; 11031af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 1111f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 1127a673c6bSDomen Puncer 1132a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 1142a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 1152a1b2dc0SSukadev Bhattiprolu opts->newinstance = 0; 1162a1b2dc0SSukadev Bhattiprolu 1177a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 1187a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 1197a673c6bSDomen Puncer int token; 1207a673c6bSDomen Puncer int option; 1217a673c6bSDomen Puncer 1227a673c6bSDomen Puncer if (!*p) 1231da177e4SLinus Torvalds continue; 1247a673c6bSDomen Puncer 1257a673c6bSDomen Puncer token = match_token(p, tokens, args); 1267a673c6bSDomen Puncer switch (token) { 1277a673c6bSDomen Puncer case Opt_uid: 1287a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1297a673c6bSDomen Puncer return -EINVAL; 13031af0abbSSukadev Bhattiprolu opts->uid = option; 13131af0abbSSukadev Bhattiprolu opts->setuid = 1; 1327a673c6bSDomen Puncer break; 1337a673c6bSDomen Puncer case Opt_gid: 1347a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1357a673c6bSDomen Puncer return -EINVAL; 13631af0abbSSukadev Bhattiprolu opts->gid = option; 13731af0abbSSukadev Bhattiprolu opts->setgid = 1; 1387a673c6bSDomen Puncer break; 1397a673c6bSDomen Puncer case Opt_mode: 1407a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 1417a673c6bSDomen Puncer return -EINVAL; 14231af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 1437a673c6bSDomen Puncer break; 1441f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1451f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 1461f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 1471f8f1e29SSukadev Bhattiprolu return -EINVAL; 1481f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 1491f8f1e29SSukadev Bhattiprolu break; 1502a1b2dc0SSukadev Bhattiprolu case Opt_newinstance: 1512a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 1522a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 1532a1b2dc0SSukadev Bhattiprolu opts->newinstance = 1; 1542a1b2dc0SSukadev Bhattiprolu break; 1551f8f1e29SSukadev Bhattiprolu #endif 1567a673c6bSDomen Puncer default: 1577a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 1581da177e4SLinus Torvalds return -EINVAL; 1591da177e4SLinus Torvalds } 1601da177e4SLinus Torvalds } 1611da177e4SLinus Torvalds 1621da177e4SLinus Torvalds return 0; 1631da177e4SLinus Torvalds } 1641da177e4SLinus Torvalds 1651f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1661f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 16753af8ee4SSukadev Bhattiprolu { 1681f8f1e29SSukadev Bhattiprolu int mode; 1691f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 1701f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 1711f8f1e29SSukadev Bhattiprolu struct inode *inode; 1721f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 17353af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 17453af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 17553af8ee4SSukadev Bhattiprolu 1761f8f1e29SSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 1771f8f1e29SSukadev Bhattiprolu 1781f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 1791f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 1801f8f1e29SSukadev Bhattiprolu rc = 0; 1811f8f1e29SSukadev Bhattiprolu goto out; 1821f8f1e29SSukadev Bhattiprolu } 1831f8f1e29SSukadev Bhattiprolu 1841f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 1851f8f1e29SSukadev Bhattiprolu if (!dentry) { 1861f8f1e29SSukadev Bhattiprolu printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n"); 1871f8f1e29SSukadev Bhattiprolu goto out; 1881f8f1e29SSukadev Bhattiprolu } 1891f8f1e29SSukadev Bhattiprolu 1901f8f1e29SSukadev Bhattiprolu /* 1911f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 1921f8f1e29SSukadev Bhattiprolu */ 1931f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 1941f8f1e29SSukadev Bhattiprolu if (!inode) { 1951f8f1e29SSukadev Bhattiprolu printk(KERN_ERR "Unable to alloc inode for ptmx node\n"); 1961f8f1e29SSukadev Bhattiprolu dput(dentry); 1971f8f1e29SSukadev Bhattiprolu goto out; 1981f8f1e29SSukadev Bhattiprolu } 1991f8f1e29SSukadev Bhattiprolu 2001f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 2011f8f1e29SSukadev Bhattiprolu inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 2021f8f1e29SSukadev Bhattiprolu 2031f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 2041f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 2051f8f1e29SSukadev Bhattiprolu 2061f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 2071f8f1e29SSukadev Bhattiprolu 2081f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 2091f8f1e29SSukadev Bhattiprolu rc = 0; 2101f8f1e29SSukadev Bhattiprolu out: 2111f8f1e29SSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 2121f8f1e29SSukadev Bhattiprolu return rc; 2131f8f1e29SSukadev Bhattiprolu } 2141f8f1e29SSukadev Bhattiprolu 2151f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 2161f8f1e29SSukadev Bhattiprolu { 2171f8f1e29SSukadev Bhattiprolu struct inode *inode; 2181f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2191f8f1e29SSukadev Bhattiprolu inode = fsi->ptmx_dentry->d_inode; 2201f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 2211f8f1e29SSukadev Bhattiprolu } 2221f8f1e29SSukadev Bhattiprolu } 2231f8f1e29SSukadev Bhattiprolu #else 2241f8f1e29SSukadev Bhattiprolu static inline void update_ptmx_mode(struct pts_fs_info *fsi) 2251f8f1e29SSukadev Bhattiprolu { 2261f8f1e29SSukadev Bhattiprolu return; 2271f8f1e29SSukadev Bhattiprolu } 2281f8f1e29SSukadev Bhattiprolu #endif 2291f8f1e29SSukadev Bhattiprolu 2301f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 2311f8f1e29SSukadev Bhattiprolu { 2321f8f1e29SSukadev Bhattiprolu int err; 2331f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 2341f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 2351f8f1e29SSukadev Bhattiprolu 2362a1b2dc0SSukadev Bhattiprolu err = parse_mount_options(data, PARSE_REMOUNT, opts); 2371f8f1e29SSukadev Bhattiprolu 2381f8f1e29SSukadev Bhattiprolu /* 2391f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 2401f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 2411f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 2421f8f1e29SSukadev Bhattiprolu * so do this even on error return. 2431f8f1e29SSukadev Bhattiprolu */ 2441f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 2451f8f1e29SSukadev Bhattiprolu 2461f8f1e29SSukadev Bhattiprolu return err; 24753af8ee4SSukadev Bhattiprolu } 24853af8ee4SSukadev Bhattiprolu 24934c80b1dSAl Viro static int devpts_show_options(struct seq_file *seq, struct dentry *root) 250b87a267eSMiklos Szeredi { 25134c80b1dSAl Viro struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb); 25231af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 25331af0abbSSukadev Bhattiprolu 25431af0abbSSukadev Bhattiprolu if (opts->setuid) 25531af0abbSSukadev Bhattiprolu seq_printf(seq, ",uid=%u", opts->uid); 25631af0abbSSukadev Bhattiprolu if (opts->setgid) 25731af0abbSSukadev Bhattiprolu seq_printf(seq, ",gid=%u", opts->gid); 25831af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 2591f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 2601f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 2611f8f1e29SSukadev Bhattiprolu #endif 262b87a267eSMiklos Szeredi 263b87a267eSMiklos Szeredi return 0; 264b87a267eSMiklos Szeredi } 265b87a267eSMiklos Szeredi 266ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 2671da177e4SLinus Torvalds .statfs = simple_statfs, 2681da177e4SLinus Torvalds .remount_fs = devpts_remount, 269b87a267eSMiklos Szeredi .show_options = devpts_show_options, 2701da177e4SLinus Torvalds }; 2711da177e4SLinus Torvalds 272e76b7c01SSukadev Bhattiprolu static void *new_pts_fs_info(void) 273e76b7c01SSukadev Bhattiprolu { 274e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 275e76b7c01SSukadev Bhattiprolu 276e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 277e76b7c01SSukadev Bhattiprolu if (!fsi) 278e76b7c01SSukadev Bhattiprolu return NULL; 279e76b7c01SSukadev Bhattiprolu 280e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 28131af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 2821f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 283e76b7c01SSukadev Bhattiprolu 284e76b7c01SSukadev Bhattiprolu return fsi; 285e76b7c01SSukadev Bhattiprolu } 286e76b7c01SSukadev Bhattiprolu 2871da177e4SLinus Torvalds static int 2881da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 2891da177e4SLinus Torvalds { 2901da177e4SLinus Torvalds struct inode *inode; 2911da177e4SLinus Torvalds 2921da177e4SLinus Torvalds s->s_blocksize = 1024; 2931da177e4SLinus Torvalds s->s_blocksize_bits = 10; 2941da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 2951da177e4SLinus Torvalds s->s_op = &devpts_sops; 2961da177e4SLinus Torvalds s->s_time_gran = 1; 2971da177e4SLinus Torvalds 298e76b7c01SSukadev Bhattiprolu s->s_fs_info = new_pts_fs_info(); 299e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 300e76b7c01SSukadev Bhattiprolu goto fail; 301e76b7c01SSukadev Bhattiprolu 3021da177e4SLinus Torvalds inode = new_inode(s); 3031da177e4SLinus Torvalds if (!inode) 3043850aba7SAl Viro goto fail; 3051da177e4SLinus Torvalds inode->i_ino = 1; 3061da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 3071da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 3081da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 3091da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 310bfe86848SMiklos Szeredi set_nlink(inode, 2); 3111da177e4SLinus Torvalds 31259e55e6cSSukadev Bhattiprolu s->s_root = d_alloc_root(inode); 3131da177e4SLinus Torvalds if (s->s_root) 3141da177e4SLinus Torvalds return 0; 3151da177e4SLinus Torvalds 316835aa440SAlan Cox printk(KERN_ERR "devpts: get root dentry failed\n"); 3171da177e4SLinus Torvalds iput(inode); 318e76b7c01SSukadev Bhattiprolu 3191da177e4SLinus Torvalds fail: 3201da177e4SLinus Torvalds return -ENOMEM; 3211da177e4SLinus Torvalds } 3221da177e4SLinus Torvalds 3238c056e5bSAndrew Morton #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 324d4076ac5SSukadev Bhattiprolu static int compare_init_pts_sb(struct super_block *s, void *p) 325d4076ac5SSukadev Bhattiprolu { 326d4076ac5SSukadev Bhattiprolu if (devpts_mnt) 327d4076ac5SSukadev Bhattiprolu return devpts_mnt->mnt_sb == s; 3282a1b2dc0SSukadev Bhattiprolu return 0; 3292a1b2dc0SSukadev Bhattiprolu } 3302a1b2dc0SSukadev Bhattiprolu 3312a1b2dc0SSukadev Bhattiprolu /* 332fc14f2feSAl Viro * devpts_mount() 333289f00e2SSukadev Bhattiprolu * 3341bd79035SSukadev Bhattiprolu * If the '-o newinstance' mount option was specified, mount a new 3351bd79035SSukadev Bhattiprolu * (private) instance of devpts. PTYs created in this instance are 3361bd79035SSukadev Bhattiprolu * independent of the PTYs in other devpts instances. 337d4076ac5SSukadev Bhattiprolu * 3381bd79035SSukadev Bhattiprolu * If the '-o newinstance' option was not specified, mount/remount the 3391bd79035SSukadev Bhattiprolu * initial kernel mount of devpts. This type of mount gives the 3401bd79035SSukadev Bhattiprolu * legacy, single-instance semantics. 341d4076ac5SSukadev Bhattiprolu * 3421bd79035SSukadev Bhattiprolu * The 'newinstance' option is needed to support multiple namespace 3431bd79035SSukadev Bhattiprolu * semantics in devpts while preserving backward compatibility of the 3441bd79035SSukadev Bhattiprolu * current 'single-namespace' semantics. i.e all mounts of devpts 3451bd79035SSukadev Bhattiprolu * without the 'newinstance' mount option should bind to the initial 346fc14f2feSAl Viro * kernel mount, like mount_single(). 347d4076ac5SSukadev Bhattiprolu * 3481bd79035SSukadev Bhattiprolu * Mounts with 'newinstance' option create a new, private namespace. 3491bd79035SSukadev Bhattiprolu * 3501bd79035SSukadev Bhattiprolu * NOTE: 3511bd79035SSukadev Bhattiprolu * 352fc14f2feSAl Viro * For single-mount semantics, devpts cannot use mount_single(), 353fc14f2feSAl Viro * because mount_single()/sget() find and use the super-block from 354d4076ac5SSukadev Bhattiprolu * the most recent mount of devpts. But that recent mount may be a 355fc14f2feSAl Viro * 'newinstance' mount and mount_single() would pick the newinstance 356d4076ac5SSukadev Bhattiprolu * super-block instead of the initial super-block. 357d4076ac5SSukadev Bhattiprolu */ 358fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, 359fc14f2feSAl Viro int flags, const char *dev_name, void *data) 3601da177e4SLinus Torvalds { 361482984f0SSukadev Bhattiprolu int error; 362482984f0SSukadev Bhattiprolu struct pts_mount_opts opts; 3631bd79035SSukadev Bhattiprolu struct super_block *s; 3642a1b2dc0SSukadev Bhattiprolu 365482984f0SSukadev Bhattiprolu error = parse_mount_options(data, PARSE_MOUNT, &opts); 366482984f0SSukadev Bhattiprolu if (error) 367fc14f2feSAl Viro return ERR_PTR(error); 368482984f0SSukadev Bhattiprolu 369482984f0SSukadev Bhattiprolu if (opts.newinstance) 3701bd79035SSukadev Bhattiprolu s = sget(fs_type, NULL, set_anon_super, NULL); 371482984f0SSukadev Bhattiprolu else 3721bd79035SSukadev Bhattiprolu s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); 373945cf2c7SSukadev Bhattiprolu 3741bd79035SSukadev Bhattiprolu if (IS_ERR(s)) 375fc14f2feSAl Viro return ERR_CAST(s); 3761bd79035SSukadev Bhattiprolu 3771bd79035SSukadev Bhattiprolu if (!s->s_root) { 3781bd79035SSukadev Bhattiprolu s->s_flags = flags; 3791bd79035SSukadev Bhattiprolu error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0); 380945cf2c7SSukadev Bhattiprolu if (error) 3811bd79035SSukadev Bhattiprolu goto out_undo_sget; 3821bd79035SSukadev Bhattiprolu s->s_flags |= MS_ACTIVE; 3831bd79035SSukadev Bhattiprolu } 384945cf2c7SSukadev Bhattiprolu 3851bd79035SSukadev Bhattiprolu memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts)); 3861bd79035SSukadev Bhattiprolu 3871bd79035SSukadev Bhattiprolu error = mknod_ptmx(s); 388945cf2c7SSukadev Bhattiprolu if (error) 38989468071SAl Viro goto out_undo_sget; 39089468071SAl Viro 391fc14f2feSAl Viro return dget(s->s_root); 392945cf2c7SSukadev Bhattiprolu 3931bd79035SSukadev Bhattiprolu out_undo_sget: 3946f5bbff9SAl Viro deactivate_locked_super(s); 395fc14f2feSAl Viro return ERR_PTR(error); 396482984f0SSukadev Bhattiprolu } 397482984f0SSukadev Bhattiprolu 3982a1b2dc0SSukadev Bhattiprolu #else 3992a1b2dc0SSukadev Bhattiprolu /* 4002a1b2dc0SSukadev Bhattiprolu * This supports only the legacy single-instance semantics (no 4012a1b2dc0SSukadev Bhattiprolu * multiple-instance semantics) 4022a1b2dc0SSukadev Bhattiprolu */ 403fc14f2feSAl Viro static struct dentry *devpts_mount(struct file_system_type *fs_type, int flags, 404fc14f2feSAl Viro const char *dev_name, void *data) 4052a1b2dc0SSukadev Bhattiprolu { 406fc14f2feSAl Viro return mount_single(fs_type, flags, data, devpts_fill_super); 4072a1b2dc0SSukadev Bhattiprolu } 4082a1b2dc0SSukadev Bhattiprolu #endif 4091da177e4SLinus Torvalds 410e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 411e76b7c01SSukadev Bhattiprolu { 412e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 413e76b7c01SSukadev Bhattiprolu 414e76b7c01SSukadev Bhattiprolu kfree(fsi); 4151f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 416e76b7c01SSukadev Bhattiprolu } 417e76b7c01SSukadev Bhattiprolu 4181da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 4191da177e4SLinus Torvalds .name = "devpts", 420fc14f2feSAl Viro .mount = devpts_mount, 421e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 4221da177e4SLinus Torvalds }; 4231da177e4SLinus Torvalds 4241da177e4SLinus Torvalds /* 4251da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 4261da177e4SLinus Torvalds * to the System V naming convention 4271da177e4SLinus Torvalds */ 4281da177e4SLinus Torvalds 42915f1a633SSukadev Bhattiprolu int devpts_new_index(struct inode *ptmx_inode) 430718a9163SSukadev Bhattiprolu { 431e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 432e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 433718a9163SSukadev Bhattiprolu int index; 4347ee7c12bSAlexey Dobriyan int ida_ret; 435718a9163SSukadev Bhattiprolu 436718a9163SSukadev Bhattiprolu retry: 437835aa440SAlan Cox if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) 438718a9163SSukadev Bhattiprolu return -ENOMEM; 439718a9163SSukadev Bhattiprolu 440718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 441e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 4427ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 443718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 4447ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 445718a9163SSukadev Bhattiprolu goto retry; 446718a9163SSukadev Bhattiprolu return -EIO; 447718a9163SSukadev Bhattiprolu } 448718a9163SSukadev Bhattiprolu 449718a9163SSukadev Bhattiprolu if (index >= pty_limit) { 450e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 451718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 452718a9163SSukadev Bhattiprolu return -EIO; 453718a9163SSukadev Bhattiprolu } 454718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 455718a9163SSukadev Bhattiprolu return index; 456718a9163SSukadev Bhattiprolu } 457718a9163SSukadev Bhattiprolu 45815f1a633SSukadev Bhattiprolu void devpts_kill_index(struct inode *ptmx_inode, int idx) 459718a9163SSukadev Bhattiprolu { 460e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 461e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 462e76b7c01SSukadev Bhattiprolu 463718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 464e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 465718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 466718a9163SSukadev Bhattiprolu } 467718a9163SSukadev Bhattiprolu 46815f1a633SSukadev Bhattiprolu int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) 4691da177e4SLinus Torvalds { 470835aa440SAlan Cox /* tty layer puts index from devpts_new_index() in here */ 471835aa440SAlan Cox int number = tty->index; 4721da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 4731da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 4741da177e4SLinus Torvalds struct dentry *dentry; 47559e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 47659e55e6cSSukadev Bhattiprolu struct inode *inode = new_inode(sb); 47759e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 47831af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 47931af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 480aa597bc1SAndrey Vagin int ret = 0; 48189a52e10SSukadev Bhattiprolu char s[12]; 4821da177e4SLinus Torvalds 4831da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 4841da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 4851da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 4861da177e4SLinus Torvalds 4871da177e4SLinus Torvalds if (!inode) 4881da177e4SLinus Torvalds return -ENOMEM; 4891da177e4SLinus Torvalds 490d0eafc7dSDavid Howells inode->i_ino = number + 3; 491d0eafc7dSDavid Howells inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); 492d0eafc7dSDavid Howells inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); 4931da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 49431af0abbSSukadev Bhattiprolu init_special_inode(inode, S_IFCHR|opts->mode, device); 4958e18e294STheodore Ts'o inode->i_private = tty; 496a6f37daaSSukadev Bhattiprolu tty->driver_data = inode; 4971da177e4SLinus Torvalds 49889a52e10SSukadev Bhattiprolu sprintf(s, "%d", number); 49989a52e10SSukadev Bhattiprolu 50059e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 50189a52e10SSukadev Bhattiprolu 50259e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 503b12d1259SAndrey Vagin if (dentry) { 50489a52e10SSukadev Bhattiprolu d_add(dentry, inode); 50559e55e6cSSukadev Bhattiprolu fsnotify_create(root->d_inode, dentry); 506aa597bc1SAndrey Vagin } else { 507aa597bc1SAndrey Vagin iput(inode); 508aa597bc1SAndrey Vagin ret = -ENOMEM; 5093972b7f6SFlorin Malita } 5101da177e4SLinus Torvalds 51159e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 5121da177e4SLinus Torvalds 513aa597bc1SAndrey Vagin return ret; 5141da177e4SLinus Torvalds } 5151da177e4SLinus Torvalds 51615f1a633SSukadev Bhattiprolu struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) 5171da177e4SLinus Torvalds { 518edfacdd6SSukadev Bhattiprolu struct dentry *dentry; 519edfacdd6SSukadev Bhattiprolu struct tty_struct *tty; 520edfacdd6SSukadev Bhattiprolu 521527b3e47SSukadev Bhattiprolu BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 5221da177e4SLinus Torvalds 523edfacdd6SSukadev Bhattiprolu /* Ensure dentry has not been deleted by devpts_pty_kill() */ 524edfacdd6SSukadev Bhattiprolu dentry = d_find_alias(pts_inode); 525edfacdd6SSukadev Bhattiprolu if (!dentry) 526527b3e47SSukadev Bhattiprolu return NULL; 527edfacdd6SSukadev Bhattiprolu 528edfacdd6SSukadev Bhattiprolu tty = NULL; 529edfacdd6SSukadev Bhattiprolu if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 530edfacdd6SSukadev Bhattiprolu tty = (struct tty_struct *)pts_inode->i_private; 531edfacdd6SSukadev Bhattiprolu 532edfacdd6SSukadev Bhattiprolu dput(dentry); 533edfacdd6SSukadev Bhattiprolu 534edfacdd6SSukadev Bhattiprolu return tty; 5351da177e4SLinus Torvalds } 5361da177e4SLinus Torvalds 53715f1a633SSukadev Bhattiprolu void devpts_pty_kill(struct tty_struct *tty) 5381da177e4SLinus Torvalds { 539a6f37daaSSukadev Bhattiprolu struct inode *inode = tty->driver_data; 54059e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(inode); 54159e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 542a6f37daaSSukadev Bhattiprolu struct dentry *dentry; 5431da177e4SLinus Torvalds 544a6f37daaSSukadev Bhattiprolu BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 545a6f37daaSSukadev Bhattiprolu 54659e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 547a6f37daaSSukadev Bhattiprolu 548a6f37daaSSukadev Bhattiprolu dentry = d_find_alias(inode); 5492a1b2dc0SSukadev Bhattiprolu 5506d6b77f1SMiklos Szeredi drop_nlink(inode); 5511da177e4SLinus Torvalds d_delete(dentry); 552835aa440SAlan Cox dput(dentry); /* d_alloc_name() in devpts_pty_new() */ 553835aa440SAlan Cox dput(dentry); /* d_find_alias above */ 554aa597bc1SAndrey Vagin 55559e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 5561da177e4SLinus Torvalds } 5571da177e4SLinus Torvalds 5581da177e4SLinus Torvalds static int __init init_devpts_fs(void) 5591da177e4SLinus Torvalds { 5601da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 5611da177e4SLinus Torvalds if (!err) { 5621da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 56393d5581eSAlan Cox if (IS_ERR(devpts_mnt)) { 5641da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 56593d5581eSAlan Cox unregister_filesystem(&devpts_fs_type); 56693d5581eSAlan Cox } 5671da177e4SLinus Torvalds } 5681da177e4SLinus Torvalds return err; 5691da177e4SLinus Torvalds } 5701da177e4SLinus Torvalds module_init(init_devpts_fs) 571