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