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 #include <linux/seq_file.h> 24 25 #define DEVPTS_SUPER_MAGIC 0x1cd1 26 27 #define DEVPTS_DEFAULT_MODE 0600 28 29 static struct vfsmount *devpts_mnt; 30 static struct dentry *devpts_root; 31 32 static struct { 33 int setuid; 34 int setgid; 35 uid_t uid; 36 gid_t gid; 37 umode_t mode; 38 } config = {.mode = DEVPTS_DEFAULT_MODE}; 39 40 enum { 41 Opt_uid, Opt_gid, Opt_mode, 42 Opt_err 43 }; 44 45 static match_table_t tokens = { 46 {Opt_uid, "uid=%u"}, 47 {Opt_gid, "gid=%u"}, 48 {Opt_mode, "mode=%o"}, 49 {Opt_err, NULL} 50 }; 51 52 static int devpts_remount(struct super_block *sb, int *flags, char *data) 53 { 54 char *p; 55 56 config.setuid = 0; 57 config.setgid = 0; 58 config.uid = 0; 59 config.gid = 0; 60 config.mode = DEVPTS_DEFAULT_MODE; 61 62 while ((p = strsep(&data, ",")) != NULL) { 63 substring_t args[MAX_OPT_ARGS]; 64 int token; 65 int option; 66 67 if (!*p) 68 continue; 69 70 token = match_token(p, tokens, args); 71 switch (token) { 72 case Opt_uid: 73 if (match_int(&args[0], &option)) 74 return -EINVAL; 75 config.uid = option; 76 config.setuid = 1; 77 break; 78 case Opt_gid: 79 if (match_int(&args[0], &option)) 80 return -EINVAL; 81 config.gid = option; 82 config.setgid = 1; 83 break; 84 case Opt_mode: 85 if (match_octal(&args[0], &option)) 86 return -EINVAL; 87 config.mode = option & S_IALLUGO; 88 break; 89 default: 90 printk(KERN_ERR "devpts: called with bogus options\n"); 91 return -EINVAL; 92 } 93 } 94 95 return 0; 96 } 97 98 static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs) 99 { 100 if (config.setuid) 101 seq_printf(seq, ",uid=%u", config.uid); 102 if (config.setgid) 103 seq_printf(seq, ",gid=%u", config.gid); 104 seq_printf(seq, ",mode=%03o", config.mode); 105 106 return 0; 107 } 108 109 static const struct super_operations devpts_sops = { 110 .statfs = simple_statfs, 111 .remount_fs = devpts_remount, 112 .show_options = devpts_show_options, 113 }; 114 115 static int 116 devpts_fill_super(struct super_block *s, void *data, int silent) 117 { 118 struct inode * inode; 119 120 s->s_blocksize = 1024; 121 s->s_blocksize_bits = 10; 122 s->s_magic = DEVPTS_SUPER_MAGIC; 123 s->s_op = &devpts_sops; 124 s->s_time_gran = 1; 125 126 inode = new_inode(s); 127 if (!inode) 128 goto fail; 129 inode->i_ino = 1; 130 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 131 inode->i_blocks = 0; 132 inode->i_uid = inode->i_gid = 0; 133 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 134 inode->i_op = &simple_dir_inode_operations; 135 inode->i_fop = &simple_dir_operations; 136 inode->i_nlink = 2; 137 138 devpts_root = s->s_root = d_alloc_root(inode); 139 if (s->s_root) 140 return 0; 141 142 printk("devpts: get root dentry failed\n"); 143 iput(inode); 144 fail: 145 return -ENOMEM; 146 } 147 148 static int devpts_get_sb(struct file_system_type *fs_type, 149 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 150 { 151 return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); 152 } 153 154 static struct file_system_type devpts_fs_type = { 155 .owner = THIS_MODULE, 156 .name = "devpts", 157 .get_sb = devpts_get_sb, 158 .kill_sb = kill_anon_super, 159 }; 160 161 /* 162 * The normal naming convention is simply /dev/pts/<number>; this conforms 163 * to the System V naming convention 164 */ 165 166 static struct dentry *get_node(int num) 167 { 168 char s[12]; 169 struct dentry *root = devpts_root; 170 mutex_lock(&root->d_inode->i_mutex); 171 return lookup_one_len(s, root, sprintf(s, "%d", num)); 172 } 173 174 int devpts_pty_new(struct tty_struct *tty) 175 { 176 int number = tty->index; 177 struct tty_driver *driver = tty->driver; 178 dev_t device = MKDEV(driver->major, driver->minor_start+number); 179 struct dentry *dentry; 180 struct inode *inode = new_inode(devpts_mnt->mnt_sb); 181 182 /* We're supposed to be given the slave end of a pty */ 183 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 184 BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 185 186 if (!inode) 187 return -ENOMEM; 188 189 inode->i_ino = number+2; 190 inode->i_uid = config.setuid ? config.uid : current->fsuid; 191 inode->i_gid = config.setgid ? config.gid : current->fsgid; 192 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 193 init_special_inode(inode, S_IFCHR|config.mode, device); 194 inode->i_private = tty; 195 196 dentry = get_node(number); 197 if (!IS_ERR(dentry) && !dentry->d_inode) { 198 d_instantiate(dentry, inode); 199 fsnotify_create(devpts_root->d_inode, dentry); 200 } 201 202 mutex_unlock(&devpts_root->d_inode->i_mutex); 203 204 return 0; 205 } 206 207 struct tty_struct *devpts_get_tty(int number) 208 { 209 struct dentry *dentry = get_node(number); 210 struct tty_struct *tty; 211 212 tty = NULL; 213 if (!IS_ERR(dentry)) { 214 if (dentry->d_inode) 215 tty = dentry->d_inode->i_private; 216 dput(dentry); 217 } 218 219 mutex_unlock(&devpts_root->d_inode->i_mutex); 220 221 return tty; 222 } 223 224 void devpts_pty_kill(int number) 225 { 226 struct dentry *dentry = get_node(number); 227 228 if (!IS_ERR(dentry)) { 229 struct inode *inode = dentry->d_inode; 230 if (inode) { 231 inode->i_nlink--; 232 d_delete(dentry); 233 dput(dentry); 234 } 235 dput(dentry); 236 } 237 mutex_unlock(&devpts_root->d_inode->i_mutex); 238 } 239 240 static int __init init_devpts_fs(void) 241 { 242 int err = register_filesystem(&devpts_fs_type); 243 if (!err) { 244 devpts_mnt = kern_mount(&devpts_fs_type); 245 if (IS_ERR(devpts_mnt)) 246 err = PTR_ERR(devpts_mnt); 247 } 248 return err; 249 } 250 251 static void __exit exit_devpts_fs(void) 252 { 253 unregister_filesystem(&devpts_fs_type); 254 mntput(devpts_mnt); 255 } 256 257 module_init(init_devpts_fs) 258 module_exit(exit_devpts_fs) 259 MODULE_LICENSE("GPL"); 260