fs/devpts/inode.c

   1 /* -*- linux-c -*- --------------------------------------------------------- *
   2  *
   3  * linux/fs/devpts/inode.c
   4  *
   5  *  Copyright 1998 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 "xattr.h"
  20
  21 #define DEVPTS_SUPER_MAGIC 0x1cd1
  22
  23 static struct vfsmount *devpts_mnt;
  24 static struct dentry *devpts_root;
  25
  26 static struct {
  27         int setuid;
  28         int setgid;
  29         uid_t   uid;
  30         gid_t   gid;
  31         umode_t mode;
  32 } config = {.mode = 0600};
  33
  34 static int devpts_remount(struct super_block *sb, int *flags, char *data)
  35 {
  36         int setuid = 0;
  37         int setgid = 0;
  38         uid_t uid = 0;
  39         gid_t gid = 0;
  40         umode_t mode = 0600;
  41         char *this_char;
  42
  43         this_char = NULL;
  44         while ((this_char = strsep(&data, ",")) != NULL) {
  45                 int n;
  46                 char dummy;
  47                 if (!*this_char)
  48                         continue;
  49                 if (sscanf(this_char, "uid=%i%c", &n, &dummy) == 1) {
  50                         setuid = 1;
  51                         uid = n;
  52                 } else if (sscanf(this_char, "gid=%i%c", &n, &dummy) == 1) {
  53                         setgid = 1;
  54                         gid = n;
  55                 } else if (sscanf(this_char, "mode=%o%c", &n, &dummy) == 1)
  56                         mode = n & ~S_IFMT;
  57                 else {
  58                         printk("devpts: called with bogus options\n");
  59                         return -EINVAL;
  60                 }
  61         }
  62         config.setuid  = setuid;
  63         config.setgid  = setgid;
  64         config.uid     = uid;
  65         config.gid     = gid;
  66         config.mode    = mode;
  67
  68         return 0;
  69 }
  70
  71 static struct super_operations devpts_sops = {
  72         .statfs         = simple_statfs,
  73         .remount_fs     = devpts_remount,
  74 };
  75
  76 static int
  77 devpts_fill_super(struct super_block *s, void *data, int silent)
  78 {
  79         struct inode * inode;
  80
  81         s->s_blocksize = 1024;
  82         s->s_blocksize_bits = 10;
  83         s->s_magic = DEVPTS_SUPER_MAGIC;
  84         s->s_op = &devpts_sops;
  85
  86         inode = new_inode(s);
  87         if (!inode)
  88                 goto fail;
  89         inode->i_ino = 1;
  90         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  91         inode->i_blocks = 0;
  92         inode->i_blksize = 1024;
  93         inode->i_uid = inode->i_gid = 0;
  94         inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
  95         inode->i_op = &simple_dir_inode_operations;
  96         inode->i_fop = &simple_dir_operations;
  97         inode->i_nlink = 2;
  98
  99         devpts_root = s->s_root = d_alloc_root(inode);
 100         if (s->s_root)
 101                 return 0;
 102
 103         printk("devpts: get root dentry failed\n");
 104         iput(inode);
 105 fail:
 106         return -ENOMEM;
 107 }
 108
 109 static struct super_block *devpts_get_sb(struct file_system_type *fs_type,
 110         int flags, const char *dev_name, void *data)
 111 {
 112         return get_sb_single(fs_type, flags, data, devpts_fill_super);
 113 }
 114
 115 static struct file_system_type devpts_fs_type = {
 116         .owner          = THIS_MODULE,
 117         .name           = "devpts",
 118         .get_sb         = devpts_get_sb,
 119         .kill_sb        = kill_anon_super,
 120 };
 121
 122 /*
 123  * The normal naming convention is simply /dev/pts/<number>; this conforms
 124  * to the System V naming convention
 125  */
 126
 127 static struct dentry *get_node(int num)
 128 {
 129         char s[10];
 130         struct dentry *root = devpts_root;
 131         down(&root->d_inode->i_sem);
 132         return lookup_one_len(s, root, sprintf(s, "%d", num));
 133 }
 134
 135 static struct inode_operations devpts_file_inode_operations = {
 136         .setxattr       = devpts_setxattr,
 137         .getxattr       = devpts_getxattr,
 138         .listxattr      = devpts_listxattr,
 139         .removexattr    = devpts_removexattr,
 140 };
 141
 142 void devpts_pty_new(int number, dev_t device)
 143 {
 144         struct dentry *dentry;
 145         struct inode *inode = new_inode(devpts_mnt->mnt_sb);
 146         if (!inode)
 147                 return;
 148         inode->i_ino = number+2;
 149         inode->i_blksize = 1024;
 150         inode->i_uid = config.setuid ? config.uid : current->fsuid;
 151         inode->i_gid = config.setgid ? config.gid : current->fsgid;
 152         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 153         init_special_inode(inode, S_IFCHR|config.mode, device);
 154         inode->i_op = &devpts_file_inode_operations;
 155
 156         dentry = get_node(number);
 157         if (!IS_ERR(dentry) && !dentry->d_inode)
 158                 d_instantiate(dentry, inode);
 159         up(&devpts_root->d_inode->i_sem);
 160 }
 161
 162 void devpts_pty_kill(int number)
 163 {
 164         struct dentry *dentry = get_node(number);
 165
 166         if (!IS_ERR(dentry)) {
 167                 struct inode *inode = dentry->d_inode;
 168                 if (inode) {
 169                         inode->i_nlink--;
 170                         d_delete(dentry);
 171                         dput(dentry);
 172                 }
 173                 dput(dentry);
 174         }
 175         up(&devpts_root->d_inode->i_sem);
 176 }
 177
 178 static int __init init_devpts_fs(void)
 179 {
 180         int err = init_devpts_xattr();
 181         if (err)
 182                 return err;
 183         err = register_filesystem(&devpts_fs_type);
 184         if (!err) {
 185                 devpts_mnt = kern_mount(&devpts_fs_type);
 186                 if (IS_ERR(devpts_mnt))
 187                         err = PTR_ERR(devpts_mnt);
 188         }
 189         return err;
 190 }
 191
 192 static void __exit exit_devpts_fs(void)
 193 {
 194         unregister_filesystem(&devpts_fs_type);
 195         mntput(devpts_mnt);
 196         exit_devpts_xattr();
 197 }
 198
 199 module_init(init_devpts_fs)
 200 module_exit(exit_devpts_fs)
 201 MODULE_LICENSE("GPL");