fs/devpts/inode.c

   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/vs_base.h>
  22 #include "xattr.h"
  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 int devpts_readdir(struct file * filp, void * dirent, filldir_t filldir)
  73 {
  74         struct dentry *dentry = filp->f_dentry;
  75         struct dentry *cursor = filp->private_data;
  76         struct list_head *p, *q = &cursor->d_child;
  77         ino_t ino;
  78         int i = filp->f_pos;
  79
  80         switch (i) {
  81                 case 0:
  82                         ino = dentry->d_inode->i_ino;
  83                         if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
  84                                 break;
  85                         filp->f_pos++;
  86                         i++;
  87                         /* fallthrough */
  88                 case 1:
  89                         ino = parent_ino(dentry);
  90                         if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
  91                                 break;
  92                         filp->f_pos++;
  93                         i++;
  94                         /* fallthrough */
  95                 default:
  96                         spin_lock(&dcache_lock);
  97                         if (filp->f_pos == 2) {
  98                                 list_del(q);
  99                                 list_add(q, &dentry->d_subdirs);
 100                         }
 101                         for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
 102                                 struct dentry *next;
 103                                 next = list_entry(p, struct dentry, d_child);
 104                                 if (d_unhashed(next) || !next->d_inode)
 105                                         continue;
 106                                 if (!vx_check(next->d_inode->i_xid, VX_IDENT))
 107                                         continue;
 108
 109                                 spin_unlock(&dcache_lock);
 110                                 if (filldir(dirent, next->d_name.name,
 111                                         next->d_name.len, filp->f_pos,
 112                                         next->d_inode->i_ino, DT_CHR) < 0)
 113                                         return 0;
 114                                 spin_lock(&dcache_lock);
 115                                 /* next is still alive */
 116                                 list_del(q);
 117                                 list_add(q, p);
 118                                 p = q;
 119                                 filp->f_pos++;
 120                         }
 121                         spin_unlock(&dcache_lock);
 122         }
 123         return 0;
 124 }
 125
 126 static struct file_operations devpts_dir_operations = {
 127         .open           = dcache_dir_open,
 128         .release        = dcache_dir_close,
 129         .llseek         = dcache_dir_lseek,
 130         .read           = generic_read_dir,
 131         .readdir        = devpts_readdir,
 132 };
 133
 134 static struct super_operations devpts_sops = {
 135         .statfs         = simple_statfs,
 136         .remount_fs     = devpts_remount,
 137 };
 138
 139 static int
 140 devpts_fill_super(struct super_block *s, void *data, int silent)
 141 {
 142         struct inode * inode;
 143
 144         s->s_blocksize = 1024;
 145         s->s_blocksize_bits = 10;
 146         s->s_magic = DEVPTS_SUPER_MAGIC;
 147         s->s_op = &devpts_sops;
 148
 149         inode = new_inode(s);
 150         if (!inode)
 151                 goto fail;
 152         inode->i_ino = 1;
 153         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 154         inode->i_blocks = 0;
 155         inode->i_blksize = 1024;
 156         inode->i_uid = inode->i_gid = 0;
 157         inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
 158         inode->i_op = &simple_dir_inode_operations;
 159         inode->i_fop = &devpts_dir_operations;
 160         inode->i_nlink = 2;
 161         inode->i_xid = vx_current_xid();
 162
 163         devpts_root = s->s_root = d_alloc_root(inode);
 164         if (s->s_root)
 165                 return 0;
 166
 167         printk("devpts: get root dentry failed\n");
 168         iput(inode);
 169 fail:
 170         return -ENOMEM;
 171 }
 172
 173 static struct super_block *devpts_get_sb(struct file_system_type *fs_type,
 174         int flags, const char *dev_name, void *data)
 175 {
 176         return get_sb_single(fs_type, flags, data, devpts_fill_super);
 177 }
 178
 179 static struct file_system_type devpts_fs_type = {
 180         .owner          = THIS_MODULE,
 181         .name           = "devpts",
 182         .get_sb         = devpts_get_sb,
 183         .kill_sb        = kill_anon_super,
 184 };
 185
 186 /*
 187  * The normal naming convention is simply /dev/pts/<number>; this conforms
 188  * to the System V naming convention
 189  */
 190
 191 static struct dentry *get_node(int num)
 192 {
 193         char s[12];
 194         struct dentry *root = devpts_root;
 195         down(&root->d_inode->i_sem);
 196         return lookup_one_len(s, root, sprintf(s, "%d", num));
 197 }
 198
 199 static int devpts_permission(struct inode *inode, int mask, struct nameidata *nd)
 200 {
 201         int ret = -EACCES;
 202
 203         if (vx_check(inode->i_xid, VX_IDENT))
 204                 ret = vfs_permission(inode, mask);
 205         return ret;
 206 }
 207
 208 static struct inode_operations devpts_file_inode_operations = {
 209         .setxattr       = devpts_setxattr,
 210         .getxattr       = devpts_getxattr,
 211         .listxattr      = devpts_listxattr,
 212         .removexattr    = devpts_removexattr,
 213         .permission     = devpts_permission,
 214 };
 215
 216 int devpts_pty_new(struct tty_struct *tty)
 217 {
 218         int number = tty->index;
 219         struct tty_driver *driver = tty->driver;
 220         dev_t device = MKDEV(driver->major, driver->minor_start+number);
 221         struct dentry *dentry;
 222         struct inode *inode = new_inode(devpts_mnt->mnt_sb);
 223
 224         /* We're supposed to be given the slave end of a pty */
 225         BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
 226         BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
 227
 228         if (!inode)
 229                 return -ENOMEM;
 230
 231         inode->i_ino = number+2;
 232         inode->i_blksize = 1024;
 233         inode->i_uid = config.setuid ? config.uid : current->fsuid;
 234         inode->i_gid = config.setgid ? config.gid : current->fsgid;
 235         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 236         init_special_inode(inode, S_IFCHR|config.mode, device);
 237         inode->i_xid = vx_current_xid();
 238         inode->i_op = &devpts_file_inode_operations;
 239         inode->u.generic_ip = tty;
 240
 241         dentry = get_node(number);
 242         if (!IS_ERR(dentry) && !dentry->d_inode)
 243                 d_instantiate(dentry, inode);
 244
 245         up(&devpts_root->d_inode->i_sem);
 246
 247         return 0;
 248 }
 249
 250 struct tty_struct *devpts_get_tty(int number)
 251 {
 252         struct dentry *dentry = get_node(number);
 253         struct tty_struct *tty;
 254
 255         tty = NULL;
 256         if (!IS_ERR(dentry)) {
 257                 if (dentry->d_inode)
 258                         tty = dentry->d_inode->u.generic_ip;
 259                 dput(dentry);
 260         }
 261
 262         up(&devpts_root->d_inode->i_sem);
 263
 264         return tty;
 265 }
 266
 267 void devpts_pty_kill(int number)
 268 {
 269         struct dentry *dentry = get_node(number);
 270
 271         if (!IS_ERR(dentry)) {
 272                 struct inode *inode = dentry->d_inode;
 273                 if (inode) {
 274                         inode->i_nlink--;
 275                         d_delete(dentry);
 276                         dput(dentry);
 277                 }
 278                 dput(dentry);
 279         }
 280         up(&devpts_root->d_inode->i_sem);
 281 }
 282
 283 static int __init init_devpts_fs(void)
 284 {
 285         int err = init_devpts_xattr();
 286         if (err)
 287                 return err;
 288         err = register_filesystem(&devpts_fs_type);
 289         if (!err) {
 290                 devpts_mnt = kern_mount(&devpts_fs_type);
 291                 if (IS_ERR(devpts_mnt))
 292                         err = PTR_ERR(devpts_mnt);
 293         }
 294         return err;
 295 }
 296
 297 static void __exit exit_devpts_fs(void)
 298 {
 299         unregister_filesystem(&devpts_fs_type);
 300         mntput(devpts_mnt);
 301         exit_devpts_xattr();
 302 }
 303
 304 module_init(init_devpts_fs)
 305 module_exit(exit_devpts_fs)
 306 MODULE_LICENSE("GPL");