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/xattr.h> 22 23 #define DEVPTS_SUPER_MAGIC 0x1cd1 24 25 extern struct xattr_handler devpts_xattr_security_handler; 26 27 static struct xattr_handler *devpts_xattr_handlers[] = { 28 #ifdef CONFIG_DEVPTS_FS_SECURITY 29 &devpts_xattr_security_handler, 30 #endif 31 NULL 32 }; 33 34 static struct inode_operations devpts_file_inode_operations = { 35 #ifdef CONFIG_DEVPTS_FS_XATTR 36 .setxattr = generic_setxattr, 37 .getxattr = generic_getxattr, 38 .listxattr = generic_listxattr, 39 .removexattr = generic_removexattr, 40 #endif 41 }; 42 43 static struct vfsmount *devpts_mnt; 44 static struct dentry *devpts_root; 45 46 static struct { 47 int setuid; 48 int setgid; 49 uid_t uid; 50 gid_t gid; 51 umode_t mode; 52 } config = {.mode = 0600}; 53 54 static int devpts_remount(struct super_block *sb, int *flags, char *data) 55 { 56 int setuid = 0; 57 int setgid = 0; 58 uid_t uid = 0; 59 gid_t gid = 0; 60 umode_t mode = 0600; 61 char *this_char; 62 63 this_char = NULL; 64 while ((this_char = strsep(&data, ",")) != NULL) { 65 int n; 66 char dummy; 67 if (!*this_char) 68 continue; 69 if (sscanf(this_char, "uid=%i%c", &n, &dummy) == 1) { 70 setuid = 1; 71 uid = n; 72 } else if (sscanf(this_char, "gid=%i%c", &n, &dummy) == 1) { 73 setgid = 1; 74 gid = n; 75 } else if (sscanf(this_char, "mode=%o%c", &n, &dummy) == 1) 76 mode = n & ~S_IFMT; 77 else { 78 printk("devpts: called with bogus options\n"); 79 return -EINVAL; 80 } 81 } 82 config.setuid = setuid; 83 config.setgid = setgid; 84 config.uid = uid; 85 config.gid = gid; 86 config.mode = mode; 87 88 return 0; 89 } 90 91 static struct super_operations devpts_sops = { 92 .statfs = simple_statfs, 93 .remount_fs = devpts_remount, 94 }; 95 96 static int 97 devpts_fill_super(struct super_block *s, void *data, int silent) 98 { 99 struct inode * inode; 100 101 s->s_blocksize = 1024; 102 s->s_blocksize_bits = 10; 103 s->s_magic = DEVPTS_SUPER_MAGIC; 104 s->s_op = &devpts_sops; 105 s->s_xattr = devpts_xattr_handlers; 106 s->s_time_gran = 1; 107 108 inode = new_inode(s); 109 if (!inode) 110 goto fail; 111 inode->i_ino = 1; 112 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 113 inode->i_blocks = 0; 114 inode->i_blksize = 1024; 115 inode->i_uid = inode->i_gid = 0; 116 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; 117 inode->i_op = &simple_dir_inode_operations; 118 inode->i_fop = &simple_dir_operations; 119 inode->i_nlink = 2; 120 121 devpts_root = s->s_root = d_alloc_root(inode); 122 if (s->s_root) 123 return 0; 124 125 printk("devpts: get root dentry failed\n"); 126 iput(inode); 127 fail: 128 return -ENOMEM; 129 } 130 131 static struct super_block *devpts_get_sb(struct file_system_type *fs_type, 132 int flags, const char *dev_name, void *data) 133 { 134 return get_sb_single(fs_type, flags, data, devpts_fill_super); 135 } 136 137 static struct file_system_type devpts_fs_type = { 138 .owner = THIS_MODULE, 139 .name = "devpts", 140 .get_sb = devpts_get_sb, 141 .kill_sb = kill_anon_super, 142 }; 143 144 /* 145 * The normal naming convention is simply /dev/pts/<number>; this conforms 146 * to the System V naming convention 147 */ 148 149 static struct dentry *get_node(int num) 150 { 151 char s[12]; 152 struct dentry *root = devpts_root; 153 down(&root->d_inode->i_sem); 154 return lookup_one_len(s, root, sprintf(s, "%d", num)); 155 } 156 157 int devpts_pty_new(struct tty_struct *tty) 158 { 159 int number = tty->index; 160 struct tty_driver *driver = tty->driver; 161 dev_t device = MKDEV(driver->major, driver->minor_start+number); 162 struct dentry *dentry; 163 struct inode *inode = new_inode(devpts_mnt->mnt_sb); 164 165 /* We're supposed to be given the slave end of a pty */ 166 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); 167 BUG_ON(driver->subtype != PTY_TYPE_SLAVE); 168 169 if (!inode) 170 return -ENOMEM; 171 172 inode->i_ino = number+2; 173 inode->i_blksize = 1024; 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_op = &devpts_file_inode_operations; 179 inode->u.generic_ip = tty; 180 181 dentry = get_node(number); 182 if (!IS_ERR(dentry) && !dentry->d_inode) 183 d_instantiate(dentry, inode); 184 185 up(&devpts_root->d_inode->i_sem); 186 187 return 0; 188 } 189 190 struct tty_struct *devpts_get_tty(int number) 191 { 192 struct dentry *dentry = get_node(number); 193 struct tty_struct *tty; 194 195 tty = NULL; 196 if (!IS_ERR(dentry)) { 197 if (dentry->d_inode) 198 tty = dentry->d_inode->u.generic_ip; 199 dput(dentry); 200 } 201 202 up(&devpts_root->d_inode->i_sem); 203 204 return tty; 205 } 206 207 void devpts_pty_kill(int number) 208 { 209 struct dentry *dentry = get_node(number); 210 211 if (!IS_ERR(dentry)) { 212 struct inode *inode = dentry->d_inode; 213 if (inode) { 214 inode->i_nlink--; 215 d_delete(dentry); 216 dput(dentry); 217 } 218 dput(dentry); 219 } 220 up(&devpts_root->d_inode->i_sem); 221 } 222 223 static int __init init_devpts_fs(void) 224 { 225 int err = register_filesystem(&devpts_fs_type); 226 if (!err) { 227 devpts_mnt = kern_mount(&devpts_fs_type); 228 if (IS_ERR(devpts_mnt)) 229 err = PTR_ERR(devpts_mnt); 230 } 231 return err; 232 } 233 234 static void __exit exit_devpts_fs(void) 235 { 236 unregister_filesystem(&devpts_fs_type); 237 mntput(devpts_mnt); 238 } 239 240 module_init(init_devpts_fs) 241 module_exit(exit_devpts_fs) 242 MODULE_LICENSE("GPL"); 243