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> 181da177e4SLinus Torvalds #include <linux/mount.h> 191da177e4SLinus Torvalds #include <linux/tty.h> 20718a9163SSukadev Bhattiprolu #include <linux/mutex.h> 21718a9163SSukadev Bhattiprolu #include <linux/idr.h> 221da177e4SLinus Torvalds #include <linux/devpts_fs.h> 237a673c6bSDomen Puncer #include <linux/parser.h> 243972b7f6SFlorin Malita #include <linux/fsnotify.h> 25b87a267eSMiklos Szeredi #include <linux/seq_file.h> 261da177e4SLinus Torvalds 271da177e4SLinus Torvalds #define DEVPTS_SUPER_MAGIC 0x1cd1 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 932a1b2dc0SSukadev Bhattiprolu static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) 941da177e4SLinus Torvalds { 957a673c6bSDomen Puncer char *p; 961da177e4SLinus Torvalds 9731af0abbSSukadev Bhattiprolu opts->setuid = 0; 9831af0abbSSukadev Bhattiprolu opts->setgid = 0; 9931af0abbSSukadev Bhattiprolu opts->uid = 0; 10031af0abbSSukadev Bhattiprolu opts->gid = 0; 10131af0abbSSukadev Bhattiprolu opts->mode = DEVPTS_DEFAULT_MODE; 1021f8f1e29SSukadev Bhattiprolu opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 1037a673c6bSDomen Puncer 1042a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 1052a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 1062a1b2dc0SSukadev Bhattiprolu opts->newinstance = 0; 1072a1b2dc0SSukadev Bhattiprolu 1087a673c6bSDomen Puncer while ((p = strsep(&data, ",")) != NULL) { 1097a673c6bSDomen Puncer substring_t args[MAX_OPT_ARGS]; 1107a673c6bSDomen Puncer int token; 1117a673c6bSDomen Puncer int option; 1127a673c6bSDomen Puncer 1137a673c6bSDomen Puncer if (!*p) 1141da177e4SLinus Torvalds continue; 1157a673c6bSDomen Puncer 1167a673c6bSDomen Puncer token = match_token(p, tokens, args); 1177a673c6bSDomen Puncer switch (token) { 1187a673c6bSDomen Puncer case Opt_uid: 1197a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1207a673c6bSDomen Puncer return -EINVAL; 12131af0abbSSukadev Bhattiprolu opts->uid = option; 12231af0abbSSukadev Bhattiprolu opts->setuid = 1; 1237a673c6bSDomen Puncer break; 1247a673c6bSDomen Puncer case Opt_gid: 1257a673c6bSDomen Puncer if (match_int(&args[0], &option)) 1267a673c6bSDomen Puncer return -EINVAL; 12731af0abbSSukadev Bhattiprolu opts->gid = option; 12831af0abbSSukadev Bhattiprolu opts->setgid = 1; 1297a673c6bSDomen Puncer break; 1307a673c6bSDomen Puncer case Opt_mode: 1317a673c6bSDomen Puncer if (match_octal(&args[0], &option)) 1327a673c6bSDomen Puncer return -EINVAL; 13331af0abbSSukadev Bhattiprolu opts->mode = option & S_IALLUGO; 1347a673c6bSDomen Puncer break; 1351f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1361f8f1e29SSukadev Bhattiprolu case Opt_ptmxmode: 1371f8f1e29SSukadev Bhattiprolu if (match_octal(&args[0], &option)) 1381f8f1e29SSukadev Bhattiprolu return -EINVAL; 1391f8f1e29SSukadev Bhattiprolu opts->ptmxmode = option & S_IALLUGO; 1401f8f1e29SSukadev Bhattiprolu break; 1412a1b2dc0SSukadev Bhattiprolu case Opt_newinstance: 1422a1b2dc0SSukadev Bhattiprolu /* newinstance makes sense only on initial mount */ 1432a1b2dc0SSukadev Bhattiprolu if (op == PARSE_MOUNT) 1442a1b2dc0SSukadev Bhattiprolu opts->newinstance = 1; 1452a1b2dc0SSukadev Bhattiprolu break; 1461f8f1e29SSukadev Bhattiprolu #endif 1477a673c6bSDomen Puncer default: 1487a673c6bSDomen Puncer printk(KERN_ERR "devpts: called with bogus options\n"); 1491da177e4SLinus Torvalds return -EINVAL; 1501da177e4SLinus Torvalds } 1511da177e4SLinus Torvalds } 1521da177e4SLinus Torvalds 1531da177e4SLinus Torvalds return 0; 1541da177e4SLinus Torvalds } 1551da177e4SLinus Torvalds 1561f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 1571f8f1e29SSukadev Bhattiprolu static int mknod_ptmx(struct super_block *sb) 15853af8ee4SSukadev Bhattiprolu { 1591f8f1e29SSukadev Bhattiprolu int mode; 1601f8f1e29SSukadev Bhattiprolu int rc = -ENOMEM; 1611f8f1e29SSukadev Bhattiprolu struct dentry *dentry; 1621f8f1e29SSukadev Bhattiprolu struct inode *inode; 1631f8f1e29SSukadev Bhattiprolu struct dentry *root = sb->s_root; 16453af8ee4SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 16553af8ee4SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 16653af8ee4SSukadev Bhattiprolu 1671f8f1e29SSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 1681f8f1e29SSukadev Bhattiprolu 1691f8f1e29SSukadev Bhattiprolu /* If we have already created ptmx node, return */ 1701f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 1711f8f1e29SSukadev Bhattiprolu rc = 0; 1721f8f1e29SSukadev Bhattiprolu goto out; 1731f8f1e29SSukadev Bhattiprolu } 1741f8f1e29SSukadev Bhattiprolu 1751f8f1e29SSukadev Bhattiprolu dentry = d_alloc_name(root, "ptmx"); 1761f8f1e29SSukadev Bhattiprolu if (!dentry) { 1771f8f1e29SSukadev Bhattiprolu printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n"); 1781f8f1e29SSukadev Bhattiprolu goto out; 1791f8f1e29SSukadev Bhattiprolu } 1801f8f1e29SSukadev Bhattiprolu 1811f8f1e29SSukadev Bhattiprolu /* 1821f8f1e29SSukadev Bhattiprolu * Create a new 'ptmx' node in this mount of devpts. 1831f8f1e29SSukadev Bhattiprolu */ 1841f8f1e29SSukadev Bhattiprolu inode = new_inode(sb); 1851f8f1e29SSukadev Bhattiprolu if (!inode) { 1861f8f1e29SSukadev Bhattiprolu printk(KERN_ERR "Unable to alloc inode for ptmx node\n"); 1871f8f1e29SSukadev Bhattiprolu dput(dentry); 1881f8f1e29SSukadev Bhattiprolu goto out; 1891f8f1e29SSukadev Bhattiprolu } 1901f8f1e29SSukadev Bhattiprolu 1911f8f1e29SSukadev Bhattiprolu inode->i_ino = 2; 1921f8f1e29SSukadev Bhattiprolu inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 1931f8f1e29SSukadev Bhattiprolu 1941f8f1e29SSukadev Bhattiprolu mode = S_IFCHR|opts->ptmxmode; 1951f8f1e29SSukadev Bhattiprolu init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2)); 1961f8f1e29SSukadev Bhattiprolu 1971f8f1e29SSukadev Bhattiprolu d_add(dentry, inode); 1981f8f1e29SSukadev Bhattiprolu 1991f8f1e29SSukadev Bhattiprolu fsi->ptmx_dentry = dentry; 2001f8f1e29SSukadev Bhattiprolu rc = 0; 2011f8f1e29SSukadev Bhattiprolu out: 2021f8f1e29SSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 2031f8f1e29SSukadev Bhattiprolu return rc; 2041f8f1e29SSukadev Bhattiprolu } 2051f8f1e29SSukadev Bhattiprolu 2061f8f1e29SSukadev Bhattiprolu static void update_ptmx_mode(struct pts_fs_info *fsi) 2071f8f1e29SSukadev Bhattiprolu { 2081f8f1e29SSukadev Bhattiprolu struct inode *inode; 2091f8f1e29SSukadev Bhattiprolu if (fsi->ptmx_dentry) { 2101f8f1e29SSukadev Bhattiprolu inode = fsi->ptmx_dentry->d_inode; 2111f8f1e29SSukadev Bhattiprolu inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode; 2121f8f1e29SSukadev Bhattiprolu } 2131f8f1e29SSukadev Bhattiprolu } 2141f8f1e29SSukadev Bhattiprolu #else 2151f8f1e29SSukadev Bhattiprolu static inline void update_ptmx_mode(struct pts_fs_info *fsi) 2161f8f1e29SSukadev Bhattiprolu { 2171f8f1e29SSukadev Bhattiprolu return; 2181f8f1e29SSukadev Bhattiprolu } 2191f8f1e29SSukadev Bhattiprolu #endif 2201f8f1e29SSukadev Bhattiprolu 2211f8f1e29SSukadev Bhattiprolu static int devpts_remount(struct super_block *sb, int *flags, char *data) 2221f8f1e29SSukadev Bhattiprolu { 2231f8f1e29SSukadev Bhattiprolu int err; 2241f8f1e29SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 2251f8f1e29SSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 2261f8f1e29SSukadev Bhattiprolu 2272a1b2dc0SSukadev Bhattiprolu err = parse_mount_options(data, PARSE_REMOUNT, opts); 2281f8f1e29SSukadev Bhattiprolu 2291f8f1e29SSukadev Bhattiprolu /* 2301f8f1e29SSukadev Bhattiprolu * parse_mount_options() restores options to default values 2311f8f1e29SSukadev Bhattiprolu * before parsing and may have changed ptmxmode. So, update the 2321f8f1e29SSukadev Bhattiprolu * mode in the inode too. Bogus options don't fail the remount, 2331f8f1e29SSukadev Bhattiprolu * so do this even on error return. 2341f8f1e29SSukadev Bhattiprolu */ 2351f8f1e29SSukadev Bhattiprolu update_ptmx_mode(fsi); 2361f8f1e29SSukadev Bhattiprolu 2371f8f1e29SSukadev Bhattiprolu return err; 23853af8ee4SSukadev Bhattiprolu } 23953af8ee4SSukadev Bhattiprolu 240b87a267eSMiklos Szeredi static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) 241b87a267eSMiklos Szeredi { 24231af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(vfs->mnt_sb); 24331af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 24431af0abbSSukadev Bhattiprolu 24531af0abbSSukadev Bhattiprolu if (opts->setuid) 24631af0abbSSukadev Bhattiprolu seq_printf(seq, ",uid=%u", opts->uid); 24731af0abbSSukadev Bhattiprolu if (opts->setgid) 24831af0abbSSukadev Bhattiprolu seq_printf(seq, ",gid=%u", opts->gid); 24931af0abbSSukadev Bhattiprolu seq_printf(seq, ",mode=%03o", opts->mode); 2501f8f1e29SSukadev Bhattiprolu #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 2511f8f1e29SSukadev Bhattiprolu seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode); 2521f8f1e29SSukadev Bhattiprolu #endif 253b87a267eSMiklos Szeredi 254b87a267eSMiklos Szeredi return 0; 255b87a267eSMiklos Szeredi } 256b87a267eSMiklos Szeredi 257ee9b6d61SJosef 'Jeff' Sipek static const struct super_operations devpts_sops = { 2581da177e4SLinus Torvalds .statfs = simple_statfs, 2591da177e4SLinus Torvalds .remount_fs = devpts_remount, 260b87a267eSMiklos Szeredi .show_options = devpts_show_options, 2611da177e4SLinus Torvalds }; 2621da177e4SLinus Torvalds 263e76b7c01SSukadev Bhattiprolu static void *new_pts_fs_info(void) 264e76b7c01SSukadev Bhattiprolu { 265e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi; 266e76b7c01SSukadev Bhattiprolu 267e76b7c01SSukadev Bhattiprolu fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); 268e76b7c01SSukadev Bhattiprolu if (!fsi) 269e76b7c01SSukadev Bhattiprolu return NULL; 270e76b7c01SSukadev Bhattiprolu 271e76b7c01SSukadev Bhattiprolu ida_init(&fsi->allocated_ptys); 27231af0abbSSukadev Bhattiprolu fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; 2731f8f1e29SSukadev Bhattiprolu fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; 274e76b7c01SSukadev Bhattiprolu 275e76b7c01SSukadev Bhattiprolu return fsi; 276e76b7c01SSukadev Bhattiprolu } 277e76b7c01SSukadev Bhattiprolu 2781da177e4SLinus Torvalds static int 2791da177e4SLinus Torvalds devpts_fill_super(struct super_block *s, void *data, int silent) 2801da177e4SLinus Torvalds { 2811da177e4SLinus Torvalds struct inode *inode; 2821da177e4SLinus Torvalds 2831da177e4SLinus Torvalds s->s_blocksize = 1024; 2841da177e4SLinus Torvalds s->s_blocksize_bits = 10; 2851da177e4SLinus Torvalds s->s_magic = DEVPTS_SUPER_MAGIC; 2861da177e4SLinus Torvalds s->s_op = &devpts_sops; 2871da177e4SLinus Torvalds s->s_time_gran = 1; 2881da177e4SLinus Torvalds 289e76b7c01SSukadev Bhattiprolu s->s_fs_info = new_pts_fs_info(); 290e76b7c01SSukadev Bhattiprolu if (!s->s_fs_info) 291e76b7c01SSukadev Bhattiprolu goto fail; 292e76b7c01SSukadev Bhattiprolu 2931da177e4SLinus Torvalds inode = new_inode(s); 2941da177e4SLinus Torvalds if (!inode) 295e76b7c01SSukadev Bhattiprolu goto free_fsi; 2961da177e4SLinus Torvalds inode->i_ino = 1; 2971da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 2981da177e4SLinus Torvalds inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 2991da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 3001da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 3011da177e4SLinus Torvalds inode->i_nlink = 2; 3021da177e4SLinus Torvalds 30359e55e6cSSukadev Bhattiprolu s->s_root = d_alloc_root(inode); 3041da177e4SLinus Torvalds if (s->s_root) 3051da177e4SLinus Torvalds return 0; 3061da177e4SLinus Torvalds 307835aa440SAlan Cox printk(KERN_ERR "devpts: get root dentry failed\n"); 3081da177e4SLinus Torvalds iput(inode); 309e76b7c01SSukadev Bhattiprolu 310e76b7c01SSukadev Bhattiprolu free_fsi: 311e76b7c01SSukadev Bhattiprolu kfree(s->s_fs_info); 3121da177e4SLinus Torvalds fail: 3131da177e4SLinus Torvalds return -ENOMEM; 3141da177e4SLinus Torvalds } 3151da177e4SLinus Torvalds 3168c056e5bSAndrew Morton #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES 317d4076ac5SSukadev Bhattiprolu static int compare_init_pts_sb(struct super_block *s, void *p) 318d4076ac5SSukadev Bhattiprolu { 319d4076ac5SSukadev Bhattiprolu if (devpts_mnt) 320d4076ac5SSukadev Bhattiprolu return devpts_mnt->mnt_sb == s; 3212a1b2dc0SSukadev Bhattiprolu return 0; 3222a1b2dc0SSukadev Bhattiprolu } 3232a1b2dc0SSukadev Bhattiprolu 3242a1b2dc0SSukadev Bhattiprolu /* 3252a1b2dc0SSukadev Bhattiprolu * Mount a new (private) instance of devpts. PTYs created in this 3262a1b2dc0SSukadev Bhattiprolu * instance are independent of the PTYs in other devpts instances. 3272a1b2dc0SSukadev Bhattiprolu */ 3282a1b2dc0SSukadev Bhattiprolu static int new_pts_mount(struct file_system_type *fs_type, int flags, 329482984f0SSukadev Bhattiprolu void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) 3302a1b2dc0SSukadev Bhattiprolu { 3312a1b2dc0SSukadev Bhattiprolu int err; 3322a1b2dc0SSukadev Bhattiprolu struct pts_fs_info *fsi; 3332a1b2dc0SSukadev Bhattiprolu 3342a1b2dc0SSukadev Bhattiprolu err = get_sb_nodev(fs_type, flags, data, devpts_fill_super, mnt); 3352a1b2dc0SSukadev Bhattiprolu if (err) 3362a1b2dc0SSukadev Bhattiprolu return err; 3372a1b2dc0SSukadev Bhattiprolu 3382a1b2dc0SSukadev Bhattiprolu fsi = DEVPTS_SB(mnt->mnt_sb); 339482984f0SSukadev Bhattiprolu memcpy(&fsi->mount_opts, opts, sizeof(opts)); 3402a1b2dc0SSukadev Bhattiprolu 341d4076ac5SSukadev Bhattiprolu return 0; 3422a1b2dc0SSukadev Bhattiprolu } 3432a1b2dc0SSukadev Bhattiprolu 3442a1b2dc0SSukadev Bhattiprolu /* 345289f00e2SSukadev Bhattiprolu * init_pts_mount() 346289f00e2SSukadev Bhattiprolu * 347289f00e2SSukadev Bhattiprolu * Mount or remount the initial kernel mount of devpts. This type of 348289f00e2SSukadev Bhattiprolu * mount maintains the legacy, single-instance semantics, while the 349289f00e2SSukadev Bhattiprolu * kernel still allows multiple-instances. 350d4076ac5SSukadev Bhattiprolu * 351d4076ac5SSukadev Bhattiprolu * This interface is needed to support multiple namespace semantics in 352d4076ac5SSukadev Bhattiprolu * devpts while preserving backward compatibility of the current 'single- 353d4076ac5SSukadev Bhattiprolu * namespace' semantics. i.e all mounts of devpts without the 'newinstance' 354d4076ac5SSukadev Bhattiprolu * mount option should bind to the initial kernel mount, like 355d4076ac5SSukadev Bhattiprolu * get_sb_single(). 356d4076ac5SSukadev Bhattiprolu * 357d4076ac5SSukadev Bhattiprolu * Mounts with 'newinstance' option create a new private namespace. 358d4076ac5SSukadev Bhattiprolu * 359d4076ac5SSukadev Bhattiprolu * But for single-mount semantics, devpts cannot use get_sb_single(), 360d4076ac5SSukadev Bhattiprolu * because get_sb_single()/sget() find and use the super-block from 361d4076ac5SSukadev Bhattiprolu * the most recent mount of devpts. But that recent mount may be a 362d4076ac5SSukadev Bhattiprolu * 'newinstance' mount and get_sb_single() would pick the newinstance 363d4076ac5SSukadev Bhattiprolu * super-block instead of the initial super-block. 364d4076ac5SSukadev Bhattiprolu * 365d4076ac5SSukadev Bhattiprolu * This interface is identical to get_sb_single() except that it 366d4076ac5SSukadev Bhattiprolu * consistently selects the 'single-namespace' superblock even in the 367d4076ac5SSukadev Bhattiprolu * presence of the private namespace (i.e 'newinstance') super-blocks. 368d4076ac5SSukadev Bhattiprolu */ 369289f00e2SSukadev Bhattiprolu static int init_pts_mount(struct file_system_type *fs_type, int flags, 370482984f0SSukadev Bhattiprolu void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) 371d4076ac5SSukadev Bhattiprolu { 372d4076ac5SSukadev Bhattiprolu struct super_block *s; 373fdbf5348SSukadev Bhattiprolu struct pts_fs_info *fsi; 374d4076ac5SSukadev Bhattiprolu int error; 375d4076ac5SSukadev Bhattiprolu 376d4076ac5SSukadev Bhattiprolu s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); 377d4076ac5SSukadev Bhattiprolu if (IS_ERR(s)) 378d4076ac5SSukadev Bhattiprolu return PTR_ERR(s); 379d4076ac5SSukadev Bhattiprolu 380d4076ac5SSukadev Bhattiprolu if (!s->s_root) { 381d4076ac5SSukadev Bhattiprolu s->s_flags = flags; 382d4076ac5SSukadev Bhattiprolu error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0); 383d4076ac5SSukadev Bhattiprolu if (error) { 384d4076ac5SSukadev Bhattiprolu up_write(&s->s_umount); 385d4076ac5SSukadev Bhattiprolu deactivate_super(s); 386d4076ac5SSukadev Bhattiprolu return error; 387d4076ac5SSukadev Bhattiprolu } 388d4076ac5SSukadev Bhattiprolu s->s_flags |= MS_ACTIVE; 389d4076ac5SSukadev Bhattiprolu } 390fdbf5348SSukadev Bhattiprolu 391a3ec947cSSukadev Bhattiprolu simple_set_mnt(mnt, s); 392482984f0SSukadev Bhattiprolu 393482984f0SSukadev Bhattiprolu fsi = DEVPTS_SB(mnt->mnt_sb); 394482984f0SSukadev Bhattiprolu memcpy(&fsi->mount_opts, opts, sizeof(opts)); 395482984f0SSukadev Bhattiprolu 396a3ec947cSSukadev Bhattiprolu return 0; 397d4076ac5SSukadev Bhattiprolu } 398d4076ac5SSukadev Bhattiprolu 399454e2398SDavid Howells static int devpts_get_sb(struct file_system_type *fs_type, 400454e2398SDavid Howells int flags, const char *dev_name, void *data, struct vfsmount *mnt) 4011da177e4SLinus Torvalds { 402482984f0SSukadev Bhattiprolu int error; 403482984f0SSukadev Bhattiprolu struct pts_mount_opts opts; 4042a1b2dc0SSukadev Bhattiprolu 405482984f0SSukadev Bhattiprolu memset(&opts, 0, sizeof(opts)); 406482984f0SSukadev Bhattiprolu if (data) { 407482984f0SSukadev Bhattiprolu error = parse_mount_options(data, PARSE_MOUNT, &opts); 408482984f0SSukadev Bhattiprolu if (error) 409482984f0SSukadev Bhattiprolu return error; 4101da177e4SLinus Torvalds } 411482984f0SSukadev Bhattiprolu 412482984f0SSukadev Bhattiprolu if (opts.newinstance) 413945cf2c7SSukadev Bhattiprolu error = new_pts_mount(fs_type, flags, data, &opts, mnt); 414482984f0SSukadev Bhattiprolu else 415945cf2c7SSukadev Bhattiprolu error = init_pts_mount(fs_type, flags, data, &opts, mnt); 416945cf2c7SSukadev Bhattiprolu 417945cf2c7SSukadev Bhattiprolu if (error) 418945cf2c7SSukadev Bhattiprolu return error; 419945cf2c7SSukadev Bhattiprolu 420945cf2c7SSukadev Bhattiprolu error = mknod_ptmx(mnt->mnt_sb); 421945cf2c7SSukadev Bhattiprolu if (error) 422945cf2c7SSukadev Bhattiprolu goto out_dput; 423945cf2c7SSukadev Bhattiprolu 424945cf2c7SSukadev Bhattiprolu return 0; 425945cf2c7SSukadev Bhattiprolu 426945cf2c7SSukadev Bhattiprolu out_dput: 427945cf2c7SSukadev Bhattiprolu dput(mnt->mnt_sb->s_root); 428945cf2c7SSukadev Bhattiprolu up_write(&mnt->mnt_sb->s_umount); 429945cf2c7SSukadev Bhattiprolu deactivate_super(mnt->mnt_sb); 430945cf2c7SSukadev Bhattiprolu return error; 431482984f0SSukadev Bhattiprolu } 432482984f0SSukadev Bhattiprolu 4332a1b2dc0SSukadev Bhattiprolu #else 4342a1b2dc0SSukadev Bhattiprolu /* 4352a1b2dc0SSukadev Bhattiprolu * This supports only the legacy single-instance semantics (no 4362a1b2dc0SSukadev Bhattiprolu * multiple-instance semantics) 4372a1b2dc0SSukadev Bhattiprolu */ 4382a1b2dc0SSukadev Bhattiprolu static int devpts_get_sb(struct file_system_type *fs_type, int flags, 4392a1b2dc0SSukadev Bhattiprolu const char *dev_name, void *data, struct vfsmount *mnt) 4402a1b2dc0SSukadev Bhattiprolu { 4412a1b2dc0SSukadev Bhattiprolu return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); 4422a1b2dc0SSukadev Bhattiprolu } 4432a1b2dc0SSukadev Bhattiprolu #endif 4441da177e4SLinus Torvalds 445e76b7c01SSukadev Bhattiprolu static void devpts_kill_sb(struct super_block *sb) 446e76b7c01SSukadev Bhattiprolu { 447e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 448e76b7c01SSukadev Bhattiprolu 449e76b7c01SSukadev Bhattiprolu kfree(fsi); 4501f8f1e29SSukadev Bhattiprolu kill_litter_super(sb); 451e76b7c01SSukadev Bhattiprolu } 452e76b7c01SSukadev Bhattiprolu 4531da177e4SLinus Torvalds static struct file_system_type devpts_fs_type = { 4541da177e4SLinus Torvalds .owner = THIS_MODULE, 4551da177e4SLinus Torvalds .name = "devpts", 4561da177e4SLinus Torvalds .get_sb = devpts_get_sb, 457e76b7c01SSukadev Bhattiprolu .kill_sb = devpts_kill_sb, 4581da177e4SLinus Torvalds }; 4591da177e4SLinus Torvalds 4601da177e4SLinus Torvalds /* 4611da177e4SLinus Torvalds * The normal naming convention is simply /dev/pts/<number>; this conforms 4621da177e4SLinus Torvalds * to the System V naming convention 4631da177e4SLinus Torvalds */ 4641da177e4SLinus Torvalds 46515f1a633SSukadev Bhattiprolu int devpts_new_index(struct inode *ptmx_inode) 466718a9163SSukadev Bhattiprolu { 467e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 468e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 469718a9163SSukadev Bhattiprolu int index; 4707ee7c12bSAlexey Dobriyan int ida_ret; 471718a9163SSukadev Bhattiprolu 472718a9163SSukadev Bhattiprolu retry: 473835aa440SAlan Cox if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) 474718a9163SSukadev Bhattiprolu return -ENOMEM; 475718a9163SSukadev Bhattiprolu 476718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 477e76b7c01SSukadev Bhattiprolu ida_ret = ida_get_new(&fsi->allocated_ptys, &index); 4787ee7c12bSAlexey Dobriyan if (ida_ret < 0) { 479718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 4807ee7c12bSAlexey Dobriyan if (ida_ret == -EAGAIN) 481718a9163SSukadev Bhattiprolu goto retry; 482718a9163SSukadev Bhattiprolu return -EIO; 483718a9163SSukadev Bhattiprolu } 484718a9163SSukadev Bhattiprolu 485718a9163SSukadev Bhattiprolu if (index >= pty_limit) { 486e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, index); 487718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 488718a9163SSukadev Bhattiprolu return -EIO; 489718a9163SSukadev Bhattiprolu } 490718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 491718a9163SSukadev Bhattiprolu return index; 492718a9163SSukadev Bhattiprolu } 493718a9163SSukadev Bhattiprolu 49415f1a633SSukadev Bhattiprolu void devpts_kill_index(struct inode *ptmx_inode, int idx) 495718a9163SSukadev Bhattiprolu { 496e76b7c01SSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 497e76b7c01SSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 498e76b7c01SSukadev Bhattiprolu 499718a9163SSukadev Bhattiprolu mutex_lock(&allocated_ptys_lock); 500e76b7c01SSukadev Bhattiprolu ida_remove(&fsi->allocated_ptys, idx); 501718a9163SSukadev Bhattiprolu mutex_unlock(&allocated_ptys_lock); 502718a9163SSukadev Bhattiprolu } 503718a9163SSukadev Bhattiprolu 50415f1a633SSukadev Bhattiprolu int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty) 5051da177e4SLinus Torvalds { 506835aa440SAlan Cox /* tty layer puts index from devpts_new_index() in here */ 507835aa440SAlan Cox int number = tty->index; 5081da177e4SLinus Torvalds struct tty_driver *driver = tty->driver; 5091da177e4SLinus Torvalds dev_t device = MKDEV(driver->major, driver->minor_start+number); 5101da177e4SLinus Torvalds struct dentry *dentry; 51159e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(ptmx_inode); 51259e55e6cSSukadev Bhattiprolu struct inode *inode = new_inode(sb); 51359e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 51431af0abbSSukadev Bhattiprolu struct pts_fs_info *fsi = DEVPTS_SB(sb); 51531af0abbSSukadev Bhattiprolu struct pts_mount_opts *opts = &fsi->mount_opts; 51689a52e10SSukadev Bhattiprolu char s[12]; 5171da177e4SLinus Torvalds 5181da177e4SLinus Torvalds /* We're supposed to be given the slave end of a pty */ 5191da177e4SLinus Torvalds BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 5201da177e4SLinus Torvalds BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 5211da177e4SLinus Torvalds 5221da177e4SLinus Torvalds if (!inode) 5231da177e4SLinus Torvalds return -ENOMEM; 5241da177e4SLinus Torvalds 525d0eafc7dSDavid Howells inode->i_ino = number + 3; 526d0eafc7dSDavid Howells inode->i_uid = opts->setuid ? opts->uid : current_fsuid(); 527d0eafc7dSDavid Howells inode->i_gid = opts->setgid ? opts->gid : current_fsgid(); 5281da177e4SLinus Torvalds inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 52931af0abbSSukadev Bhattiprolu init_special_inode(inode, S_IFCHR|opts->mode, device); 5308e18e294STheodore Ts'o inode->i_private = tty; 531a6f37daaSSukadev Bhattiprolu tty->driver_data = inode; 5321da177e4SLinus Torvalds 53389a52e10SSukadev Bhattiprolu sprintf(s, "%d", number); 53489a52e10SSukadev Bhattiprolu 53559e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 53689a52e10SSukadev Bhattiprolu 53759e55e6cSSukadev Bhattiprolu dentry = d_alloc_name(root, s); 53889a52e10SSukadev Bhattiprolu if (!IS_ERR(dentry)) { 53989a52e10SSukadev Bhattiprolu d_add(dentry, inode); 54059e55e6cSSukadev Bhattiprolu fsnotify_create(root->d_inode, dentry); 5413972b7f6SFlorin Malita } 5421da177e4SLinus Torvalds 54359e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 5441da177e4SLinus Torvalds 5451da177e4SLinus Torvalds return 0; 5461da177e4SLinus Torvalds } 5471da177e4SLinus Torvalds 54815f1a633SSukadev Bhattiprolu struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number) 5491da177e4SLinus Torvalds { 550527b3e47SSukadev Bhattiprolu BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 5511da177e4SLinus Torvalds 552527b3e47SSukadev Bhattiprolu if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) 553527b3e47SSukadev Bhattiprolu return (struct tty_struct *)pts_inode->i_private; 554527b3e47SSukadev Bhattiprolu return NULL; 5551da177e4SLinus Torvalds } 5561da177e4SLinus Torvalds 55715f1a633SSukadev Bhattiprolu void devpts_pty_kill(struct tty_struct *tty) 5581da177e4SLinus Torvalds { 559a6f37daaSSukadev Bhattiprolu struct inode *inode = tty->driver_data; 56059e55e6cSSukadev Bhattiprolu struct super_block *sb = pts_sb_from_inode(inode); 56159e55e6cSSukadev Bhattiprolu struct dentry *root = sb->s_root; 562a6f37daaSSukadev Bhattiprolu struct dentry *dentry; 5631da177e4SLinus Torvalds 564a6f37daaSSukadev Bhattiprolu BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR)); 565a6f37daaSSukadev Bhattiprolu 56659e55e6cSSukadev Bhattiprolu mutex_lock(&root->d_inode->i_mutex); 567a6f37daaSSukadev Bhattiprolu 568a6f37daaSSukadev Bhattiprolu dentry = d_find_alias(inode); 5692a1b2dc0SSukadev Bhattiprolu if (IS_ERR(dentry)) 5702a1b2dc0SSukadev Bhattiprolu goto out; 5712a1b2dc0SSukadev Bhattiprolu 5722a1b2dc0SSukadev Bhattiprolu if (dentry) { 5731da177e4SLinus Torvalds inode->i_nlink--; 5741da177e4SLinus Torvalds d_delete(dentry); 575835aa440SAlan Cox dput(dentry); /* d_alloc_name() in devpts_pty_new() */ 5761da177e4SLinus Torvalds } 577a6f37daaSSukadev Bhattiprolu 578835aa440SAlan Cox dput(dentry); /* d_find_alias above */ 5792a1b2dc0SSukadev Bhattiprolu out: 58059e55e6cSSukadev Bhattiprolu mutex_unlock(&root->d_inode->i_mutex); 5811da177e4SLinus Torvalds } 5821da177e4SLinus Torvalds 5831da177e4SLinus Torvalds static int __init init_devpts_fs(void) 5841da177e4SLinus Torvalds { 5851da177e4SLinus Torvalds int err = register_filesystem(&devpts_fs_type); 5861da177e4SLinus Torvalds if (!err) { 5871da177e4SLinus Torvalds devpts_mnt = kern_mount(&devpts_fs_type); 5881da177e4SLinus Torvalds if (IS_ERR(devpts_mnt)) 5891da177e4SLinus Torvalds err = PTR_ERR(devpts_mnt); 5901da177e4SLinus Torvalds } 5911da177e4SLinus Torvalds return err; 5921da177e4SLinus Torvalds } 5931da177e4SLinus Torvalds 5941da177e4SLinus Torvalds static void __exit exit_devpts_fs(void) 5951da177e4SLinus Torvalds { 5961da177e4SLinus Torvalds unregister_filesystem(&devpts_fs_type); 5971da177e4SLinus Torvalds mntput(devpts_mnt); 5981da177e4SLinus Torvalds } 5991da177e4SLinus Torvalds 6001da177e4SLinus Torvalds module_init(init_devpts_fs) 6011da177e4SLinus Torvalds module_exit(exit_devpts_fs) 6021da177e4SLinus Torvalds MODULE_LICENSE("GPL"); 603