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