sys/dev/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 <drm/drmP.h>
  37 #include "drm_internal.h"
  38
  39 /**
  40  * Find the file with the given magic number.
  41  *
  42  * \param dev DRM device.
  43  * \param magic magic number.
  44  *
  45  * Searches in drm_device::magiclist within all files with the same hash key
  46  * the one with matching magic number, while holding the drm_device::struct_mutex
  47  * lock.
  48  */
  49 static struct drm_file *drm_find_file(struct drm_device *dev, drm_magic_t magic)
  50 {
  51         struct drm_file *retval = NULL;
  52         struct drm_magic_entry *pt;
  53         struct drm_hash_item *hash;
  54
  55         mutex_lock(&dev->struct_mutex);
  56         if (!drm_ht_find_item(&dev->magiclist, (unsigned long)magic, &hash)) {
  57                 pt = drm_hash_entry(hash, struct drm_magic_entry, hash_item);
  58                 retval = pt->priv;
  59         }
  60         mutex_unlock(&dev->struct_mutex);
  61         return retval;
  62 }
  63
  64 /**
  65  * Inserts the given magic number into the hash table of used magic number
  66  * lists.
  67  */
  68 static int drm_add_magic(struct drm_device *dev, struct drm_file *priv,
  69                          drm_magic_t magic)
  70 {
  71         struct drm_magic_entry *entry;
  72
  73         DRM_DEBUG("%d\n", magic);
  74
  75         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
  76         if (!entry)
  77                 return -ENOMEM;
  78         entry->priv = priv;
  79         entry->hash_item.key = (unsigned long)magic;
  80         mutex_lock(&dev->struct_mutex);
  81         drm_ht_insert_item(&dev->magiclist, &entry->hash_item);
  82         list_add_tail(&entry->head, &dev->magicfree);
  83         mutex_unlock(&dev->struct_mutex);
  84
  85         return 0;
  86 }
  87
  88 /**
  89  * Removes the given magic number from the hash table of used magic number
  90  * lists.
  91  */
  92 static int drm_remove_magic(struct drm_device *dev, drm_magic_t magic)
  93 {
  94         struct drm_magic_entry *pt;
  95         struct drm_hash_item *hash;
  96
  97         DRM_DEBUG("%d\n", magic);
  98
  99         if (drm_ht_find_item(&dev->magiclist, (unsigned long)magic, &hash)) {
 100                 return -EINVAL;
 101         }
 102         pt = drm_hash_entry(hash, struct drm_magic_entry, hash_item);
 103         drm_ht_remove_item(&dev->magiclist, hash);
 104         list_del(&pt->head);
 105
 106         kfree(pt);
 107
 108         return 0;
 109 }
 110
 111 /**
 112  * Get a unique magic number (ioctl).
 113  *
 114  * \param inode device inode.
 115  * \param file_priv DRM file private.
 116  * \param cmd command.
 117  * \param arg pointer to a resulting drm_auth structure.
 118  * \return zero on success, or a negative number on failure.
 119  *
 120  * If there is a magic number in drm_file::magic then use it, otherwise
 121  * searches an unique non-zero magic number and add it associating it with \p
 122  * file_priv.
 123  * This ioctl needs protection by the drm_global_mutex, which protects
 124  * struct drm_file::magic and struct drm_magic_entry::priv.
 125  */
 126 int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
 127 {
 128         static drm_magic_t sequence = 0;
 129         static struct spinlock lock = SPINLOCK_INITIALIZER(&lock, "drm_gm");
 130         struct drm_auth *auth = data;
 131
 132         /* Find unique magic */
 133         if (file_priv->magic) {
 134                 auth->magic = file_priv->magic;
 135         } else {
 136                 do {
 137                         spin_lock(&lock);
 138                         if (!sequence)
 139                                 ++sequence;     /* reserve 0 */
 140                         auth->magic = sequence++;
 141                         spin_unlock(&lock);
 142                 } while (drm_find_file(dev, auth->magic));
 143                 file_priv->magic = auth->magic;
 144                 drm_add_magic(dev, file_priv, auth->magic);
 145         }
 146
 147         DRM_DEBUG("%u\n", auth->magic);
 148
 149         return 0;
 150 }
 151
 152 /**
 153  * drm_authmagic - Authenticate client with a magic
 154  * @dev: DRM device to operate on
 155  * @data: ioctl data containing the drm_auth object
 156  * @file_priv: DRM file that performs the operation
 157  *
 158  * This looks up a DRM client by the passed magic and authenticates it.
 159  *
 160  * Returns: 0 on success, negative error code on failure.
 161  */
 162 int drm_authmagic(struct drm_device *dev, void *data,
 163                   struct drm_file *file_priv)
 164 {
 165         struct drm_auth *auth = data;
 166         struct drm_file *file;
 167
 168         DRM_DEBUG("%u\n", auth->magic);
 169
 170         mutex_lock(&dev->struct_mutex);
 171         file = drm_find_file(dev, auth->magic);
 172         if (file) {
 173                 file->authenticated = 1;
 174                 drm_remove_magic(dev, auth->magic);
 175         }
 176         mutex_unlock(&dev->struct_mutex);
 177
 178         return file ? 0 : -EINVAL;
 179 }