drivers/char/drm/drm_auth.c

   1 /**
   2  * \file drm_auth.c
   3  * IOCTLs for authentication
   4  *
   5  * \author Rickard E. (Rik) Faith <faith@valinux.com>
   6  * \author Gareth Hughes <gareth@valinux.com>
   7  */
   8
   9 /*
  10  * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
  11  *
  12  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
  13  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
  14  * All Rights Reserved.
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a
  17  * copy of this software and associated documentation files (the "Software"),
  18  * to deal in the Software without restriction, including without limitation
  19  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  20  * and/or sell copies of the Software, and to permit persons to whom the
  21  * Software is furnished to do so, subject to the following conditions:
  22  *
  23  * The above copyright notice and this permission notice (including the next
  24  * paragraph) shall be included in all copies or substantial portions of the
  25  * Software.
  26  *
  27  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  28  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  29  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  30  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  31  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  32  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  33  * OTHER DEALINGS IN THE SOFTWARE.
  34  */
  35
  36 #include "drmP.h"
  37
  38 /**
  39  * Find the file with the given magic number.
  40  *
  41  * \param dev DRM device.
  42  * \param magic magic number.
  43  *
  44  * Searches in drm_device::magiclist within all files with the same hash key
  45  * the one with matching magic number, while holding the drm_device::struct_mutex
  46  * lock.
  47  */
  48 static drm_file_t *drm_find_file(drm_device_t * dev, drm_magic_t magic)
  49 {
  50         drm_file_t *retval = NULL;
  51         drm_magic_entry_t *pt;
  52         drm_hash_item_t *hash;
  53
  54         mutex_lock(&dev->struct_mutex);
  55         if (!drm_ht_find_item(&dev->magiclist, (unsigned long)magic, &hash)) {
  56                 pt = drm_hash_entry(hash, drm_magic_entry_t, hash_item);
  57                 retval = pt->priv;
  58         }
  59         mutex_unlock(&dev->struct_mutex);
  60         return retval;
  61 }
  62
  63 /**
  64  * Adds a magic number.
  65  *
  66  * \param dev DRM device.
  67  * \param priv file private data.
  68  * \param magic magic number.
  69  *
  70  * Creates a drm_magic_entry structure and appends to the linked list
  71  * associated the magic number hash key in drm_device::magiclist, while holding
  72  * the drm_device::struct_mutex lock.
  73  */
  74 static int drm_add_magic(drm_device_t * dev, drm_file_t * priv,
  75                          drm_magic_t magic)
  76 {
  77         drm_magic_entry_t *entry;
  78
  79         DRM_DEBUG("%d\n", magic);
  80
  81         entry = drm_alloc(sizeof(*entry), DRM_MEM_MAGIC);
  82         if (!entry)
  83                 return -ENOMEM;
  84         memset(entry, 0, sizeof(*entry));
  85         entry->priv = priv;
  86
  87         entry->hash_item.key = (unsigned long)magic;
  88         mutex_lock(&dev->struct_mutex);
  89         drm_ht_insert_item(&dev->magiclist, &entry->hash_item);
  90         list_add_tail(&entry->head, &dev->magicfree);
  91         mutex_unlock(&dev->struct_mutex);
  92
  93         return 0;
  94 }
  95
  96 /**
  97  * Remove a magic number.
  98  *
  99  * \param dev DRM device.
 100  * \param magic magic number.
 101  *
 102  * Searches and unlinks the entry in drm_device::magiclist with the magic
 103  * number hash key, while holding the drm_device::struct_mutex lock.
 104  */
 105 static int drm_remove_magic(drm_device_t * dev, drm_magic_t magic)
 106 {
 107         drm_magic_entry_t *pt;
 108         drm_hash_item_t *hash;
 109
 110         DRM_DEBUG("%d\n", magic);
 111
 112         mutex_lock(&dev->struct_mutex);
 113         if (drm_ht_find_item(&dev->magiclist, (unsigned long)magic, &hash)) {
 114                 mutex_unlock(&dev->struct_mutex);
 115                 return -EINVAL;
 116         }
 117         pt = drm_hash_entry(hash, drm_magic_entry_t, hash_item);
 118         drm_ht_remove_item(&dev->magiclist, hash);
 119         list_del(&pt->head);
 120         mutex_unlock(&dev->struct_mutex);
 121
 122         drm_free(pt, sizeof(*pt), DRM_MEM_MAGIC);
 123
 124         return -EINVAL;
 125 }
 126
 127 /**
 128  * Get a unique magic number (ioctl).
 129  *
 130  * \param inode device inode.
 131  * \param filp file pointer.
 132  * \param cmd command.
 133  * \param arg pointer to a resulting drm_auth structure.
 134  * \return zero on success, or a negative number on failure.
 135  *
 136  * If there is a magic number in drm_file::magic then use it, otherwise
 137  * searches an unique non-zero magic number and add it associating it with \p
 138  * filp.
 139  */
 140 int drm_getmagic(struct inode *inode, struct file *filp,
 141                  unsigned int cmd, unsigned long arg)
 142 {
 143         static drm_magic_t sequence = 0;
 144         static DEFINE_SPINLOCK(lock);
 145         drm_file_t *priv = filp->private_data;
 146         drm_device_t *dev = priv->head->dev;
 147         drm_auth_t auth;
 148
 149         /* Find unique magic */
 150         if (priv->magic) {
 151                 auth.magic = priv->magic;
 152         } else {
 153                 do {
 154                         spin_lock(&lock);
 155                         if (!sequence)
 156                                 ++sequence;     /* reserve 0 */
 157                         auth.magic = sequence++;
 158                         spin_unlock(&lock);
 159                 } while (drm_find_file(dev, auth.magic));
 160                 priv->magic = auth.magic;
 161                 drm_add_magic(dev, priv, auth.magic);
 162         }
 163
 164         DRM_DEBUG("%u\n", auth.magic);
 165         if (copy_to_user((drm_auth_t __user *) arg, &auth, sizeof(auth)))
 166                 return -EFAULT;
 167         return 0;
 168 }
 169
 170 /**
 171  * Authenticate with a magic.
 172  *
 173  * \param inode device inode.
 174  * \param filp file pointer.
 175  * \param cmd command.
 176  * \param arg pointer to a drm_auth structure.
 177  * \return zero if authentication successed, or a negative number otherwise.
 178  *
 179  * Checks if \p filp is associated with the magic number passed in \arg.
 180  */
 181 int drm_authmagic(struct inode *inode, struct file *filp,
 182                   unsigned int cmd, unsigned long arg)
 183 {
 184         drm_file_t *priv = filp->private_data;
 185         drm_device_t *dev = priv->head->dev;
 186         drm_auth_t auth;
 187         drm_file_t *file;
 188
 189         if (copy_from_user(&auth, (drm_auth_t __user *) arg, sizeof(auth)))
 190                 return -EFAULT;
 191         DRM_DEBUG("%u\n", auth.magic);
 192         if ((file = drm_find_file(dev, auth.magic))) {
 193                 file->authenticated = 1;
 194                 drm_remove_magic(dev, auth.magic);
 195                 return 0;
 196         }
 197         return -EINVAL;
 198 }