1 /* -*- linux-c -*- --------------------------------------------------------- * 2 * 3 * linux/fs/devpts/inode.c 4 * 5 * Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved 6 * 7 * This file is part of the Linux kernel and is made available under 8 * the terms of the GNU General Public License, version 2, or at your 9 * option, any later version, incorporated herein by reference. 10 * 11 * ------------------------------------------------------------------------- */ 12 13 #include <linux/module.h> 14 #include <linux/init.h> 15 #include <linux/fs.h> 16 #include <linux/sched.h> 17 #include <linux/namei.h> 18 #include <linux/mount.h> 19 #include <linux/tty.h> 20 #include <linux/devpts_fs.h> 21 #include <linux/parser.h> 22 #include <linux/fsnotify.h> 23 24 #define DEVPTS_SUPER_MAGIC 0x1cd1 25 26 static struct vfsmount *devpts_mnt; 27 static struct dentry *devpts_root; 28 29 static struct { 30 int setuid; 31 int setgid; 32 uid_t uid; 33 gid_t gid; 34 umode_t mode; 35 } config = {.mode = 0600}; 36 37 enum { 38 Opt_uid, Opt_gid, Opt_mode, 39 Opt_err 40 }; 41 42 static match_table_t tokens = { 43 {Opt_uid, "uid=%u"}, 44 {Opt_gid, "gid=%u"}, 45 {Opt_mode, "mode=%o"}, 46 {Opt_err, NULL} 47 }; 48 49 static int devpts_remount(struct super_block *sb, int *flags, char *data) 50 { 51 char *p; 52 53 config.setuid = 0; 54 config.setgid = 0; 55 config.uid = 0; 56 config.gid = 0; 57 config.mode = 0600; 58 59 while ((p = strsep(&data, ",")) != NULL) { 60 substring_t args[MAX_OPT_ARGS]; 61 int token; 62 int option; 63 64 if (!*p) 65 continue; 66 67 token = match_token(p, tokens, args); 68 switch (token) { 69 case Opt_uid: 70 if (match_int(&args[0], &option)) 71 return -EINVAL; 72 config.uid = option; 73 config.setuid = 1; 74 break; 75 case Opt_gid: 76 if (match_int(&args[0], &option)) 77 return -EINVAL; 78 config.gid = option; 79 config.setgid = 1; 80 break; 81 case Opt_mode: 82 if (match_octal(&args[0], &option)) 83 return -EINVAL; 84 config.mode = option & ~S_IFMT; 85 break; 86 default: 87 printk(KERN_ERR "devpts: called with bogus options\n"); 88 return -EINVAL; 89 } 90 } 91 92 return 0; 93 } 94 95 static const struct super_operations devpts_sops = { 96 .statfs = simple_statfs, 97 .remount_fs = devpts_remount, 98 }; 99 100 static int 101 devpts_fill_super(struct super_block *s, void *data, int silent) 102 { 103 struct inode * inode; 104 105 s->s_blocksize = 1024; 106 s->s_blocksize_bits = 10; 107 s->s_magic = DEVPTS_SUPER_MAGIC; 108 s->s_op = &devpts_sops; 109 s->s_time_gran = 1; 110 111 inode = new_inode(s); 112 if (!inode) 113 goto fail; 114 inode->i_ino = 1; 115 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 116 inode->i_blocks = 0; 117 inode->i_uid = inode->i_gid = 0; 118 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 119 inode->i_op = &simple_dir_inode_operations; 120 inode->i_fop = &simple_dir_operations; 121 inode->i_nlink = 2; 122 123 devpts_root = s->s_root = d_alloc_root(inode); 124 if (s->s_root) 125 return 0; 126 127 printk("devpts: get root dentry failed\n"); 128 iput(inode); 129 fail: 130 return -ENOMEM; 131 } 132 133 static int devpts_get_sb(struct file_system_type *fs_type, 134 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 135 { 136 return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); 137 } 138 139 static struct file_system_type devpts_fs_type = { 140 .owner = THIS_MODULE, 141 .name = "devpts", 142 .get_sb = devpts_get_sb, 143 .kill_sb = kill_anon_super, 144 }; 145 146 /* 147 * The normal naming convention is simply /dev/pts/<number>; this conforms 148 * to the System V naming convention 149 */ 150 151 static struct dentry *get_node(int num) 152 { 153 char s[12]; 154 struct dentry *root = devpts_root; 155 mutex_lock(&root->d_inode->i_mutex); 156 return lookup_one_len(s, root, sprintf(s, "%d", num)); 157 } 158 159 int devpts_pty_new(struct tty_struct *tty) 160 { 161 int number = tty->index; 162 struct tty_driver *driver = tty->driver; 163 dev_t device = MKDEV(driver->major, driver->minor_start+number); 164 struct dentry *dentry; 165 struct inode *inode = new_inode(devpts_mnt->mnt_sb); 166 167 /* We're supposed to be given the slave end of a pty */ 168 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 169 BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 170 171 if (!inode) 172 return -ENOMEM; 173 174 inode->i_ino = number+2; 175 inode->i_uid = config.setuid ? config.uid : current->fsuid; 176 inode->i_gid = config.setgid ? config.gid : current->fsgid; 177 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 178 init_special_inode(inode, S_IFCHR|config.mode, device); 179 inode->i_private = tty; 180 181 dentry = get_node(number); 182 if (!IS_ERR(dentry) && !dentry->d_inode) { 183 d_instantiate(dentry, inode); 184 fsnotify_create(devpts_root->d_inode, dentry); 185 } 186 187 mutex_unlock(&devpts_root->d_inode->i_mutex); 188 189 return 0; 190 } 191 192 struct tty_struct *devpts_get_tty(int number) 193 { 194 struct dentry *dentry = get_node(number); 195 struct tty_struct *tty; 196 197 tty = NULL; 198 if (!IS_ERR(dentry)) { 199 if (dentry->d_inode) 200 tty = dentry->d_inode->i_private; 201 dput(dentry); 202 } 203 204 mutex_unlock(&devpts_root->d_inode->i_mutex); 205 206 return tty; 207 } 208 209 void devpts_pty_kill(int number) 210 { 211 struct dentry *dentry = get_node(number); 212 213 if (!IS_ERR(dentry)) { 214 struct inode *inode = dentry->d_inode; 215 if (inode) { 216 inode->i_nlink--; 217 d_delete(dentry); 218 dput(dentry); 219 } 220 dput(dentry); 221 } 222 mutex_unlock(&devpts_root->d_inode->i_mutex); 223 } 224 225 static int __init init_devpts_fs(void) 226 { 227 int err = register_filesystem(&devpts_fs_type); 228 if (!err) { 229 devpts_mnt = kern_mount(&devpts_fs_type); 230 if (IS_ERR(devpts_mnt)) 231 err = PTR_ERR(devpts_mnt); 232 } 233 return err; 234 } 235 236 static void __exit exit_devpts_fs(void) 237 { 238 unregister_filesystem(&devpts_fs_type); 239 mntput(devpts_mnt); 240 } 241 242 module_init(init_devpts_fs) 243 module_exit(exit_devpts_fs) 244 MODULE_LICENSE("GPL"); 245