drivers/char/drm/drm_auth.c

   1 /**
   2  * \file drm_auth.h
   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  * Generate a hash key from a magic.
  40  *
  41  * \param magic magic.
  42  * \return hash key.
  43  *
  44  * The key is the modulus of the hash table size, #DRM_HASH_SIZE, which must be
  45  * a power of 2.
  46  */
  47 static int drm_hash_magic(drm_magic_t magic)
  48 {
  49         return magic & (DRM_HASH_SIZE-1);
  50 }
  51
  52 /**
  53  * Find the file with the given magic number.
  54  *
  55  * \param dev DRM device.
  56  * \param magic magic number.
  57  *
  58  * Searches in drm_device::magiclist within all files with the same hash key
  59  * the one with matching magic number, while holding the drm_device::struct_sem
  60  * lock.
  61  */
  62 static drm_file_t *drm_find_file(drm_device_t *dev, drm_magic_t magic)
  63 {
  64         drm_file_t        *retval = NULL;
  65         drm_magic_entry_t *pt;
  66         int               hash    = drm_hash_magic(magic);
  67
  68         down(&dev->struct_sem);
  69         for (pt = dev->magiclist[hash].head; pt; pt = pt->next) {
  70                 if (pt->magic == magic) {
  71                         retval = pt->priv;
  72                         break;
  73                 }
  74         }
  75         up(&dev->struct_sem);
  76         return retval;
  77 }
  78
  79 /**
  80  * Adds a magic number.
  81  *
  82  * \param dev DRM device.
  83  * \param priv file private data.
  84  * \param magic magic number.
  85  *
  86  * Creates a drm_magic_entry structure and appends to the linked list
  87  * associated the magic number hash key in drm_device::magiclist, while holding
  88  * the drm_device::struct_sem lock.
  89  */
  90 int drm_add_magic(drm_device_t *dev, drm_file_t *priv, drm_magic_t magic)
  91 {
  92         int               hash;
  93         drm_magic_entry_t *entry;
  94
  95         DRM_DEBUG("%d\n", magic);
  96
  97         hash         = drm_hash_magic(magic);
  98         entry        = drm_alloc(sizeof(*entry), DRM_MEM_MAGIC);
  99         if (!entry) return -ENOMEM;
 100         memset(entry, 0, sizeof(*entry));
 101         entry->magic = magic;
 102         entry->priv  = priv;
 103         entry->next  = NULL;
 104
 105         down(&dev->struct_sem);
 106         if (dev->magiclist[hash].tail) {
 107                 dev->magiclist[hash].tail->next = entry;
 108                 dev->magiclist[hash].tail       = entry;
 109         } else {
 110                 dev->magiclist[hash].head       = entry;
 111                 dev->magiclist[hash].tail       = entry;
 112         }
 113         up(&dev->struct_sem);
 114
 115         return 0;
 116 }
 117
 118 /**
 119  * Remove a magic number.
 120  *
 121  * \param dev DRM device.
 122  * \param magic magic number.
 123  *
 124  * Searches and unlinks the entry in drm_device::magiclist with the magic
 125  * number hash key, while holding the drm_device::struct_sem lock.
 126  */
 127 int drm_remove_magic(drm_device_t *dev, drm_magic_t magic)
 128 {
 129         drm_magic_entry_t *prev = NULL;
 130         drm_magic_entry_t *pt;
 131         int               hash;
 132
 133
 134         DRM_DEBUG("%d\n", magic);
 135         hash = drm_hash_magic(magic);
 136
 137         down(&dev->struct_sem);
 138         for (pt = dev->magiclist[hash].head; pt; prev = pt, pt = pt->next) {
 139                 if (pt->magic == magic) {
 140                         if (dev->magiclist[hash].head == pt) {
 141                                 dev->magiclist[hash].head = pt->next;
 142                         }
 143                         if (dev->magiclist[hash].tail == pt) {
 144                                 dev->magiclist[hash].tail = prev;
 145                         }
 146                         if (prev) {
 147                                 prev->next = pt->next;
 148                         }
 149                         up(&dev->struct_sem);
 150                         return 0;
 151                 }
 152         }
 153         up(&dev->struct_sem);
 154
 155         drm_free(pt, sizeof(*pt), DRM_MEM_MAGIC);
 156
 157         return -EINVAL;
 158 }
 159
 160 /**
 161  * Get a unique magic number (ioctl).
 162  *
 163  * \param inode device inode.
 164  * \param filp file pointer.
 165  * \param cmd command.
 166  * \param arg pointer to a resulting drm_auth structure.
 167  * \return zero on success, or a negative number on failure.
 168  *
 169  * If there is a magic number in drm_file::magic then use it, otherwise
 170  * searches an unique non-zero magic number and add it associating it with \p
 171  * filp.
 172  */
 173 int drm_getmagic(struct inode *inode, struct file *filp,
 174                   unsigned int cmd, unsigned long arg)
 175 {
 176         static drm_magic_t sequence = 0;
 177         static DEFINE_SPINLOCK(lock);
 178         drm_file_t         *priv    = filp->private_data;
 179         drm_device_t       *dev     = priv->head->dev;
 180         drm_auth_t         auth;
 181
 182                                 /* Find unique magic */
 183         if (priv->magic) {
 184                 auth.magic = priv->magic;
 185         } else {
 186                 do {
 187                         spin_lock(&lock);
 188                         if (!sequence) ++sequence; /* reserve 0 */
 189                         auth.magic = sequence++;
 190                         spin_unlock(&lock);
 191                 } while (drm_find_file(dev, auth.magic));
 192                 priv->magic = auth.magic;
 193                 drm_add_magic(dev, priv, auth.magic);
 194         }
 195
 196         DRM_DEBUG("%u\n", auth.magic);
 197         if (copy_to_user((drm_auth_t __user *)arg, &auth, sizeof(auth)))
 198                 return -EFAULT;
 199         return 0;
 200 }
 201
 202 /**
 203  * Authenticate with a magic.
 204  *
 205  * \param inode device inode.
 206  * \param filp file pointer.
 207  * \param cmd command.
 208  * \param arg pointer to a drm_auth structure.
 209  * \return zero if authentication successed, or a negative number otherwise.
 210  *
 211  * Checks if \p filp is associated with the magic number passed in \arg.
 212  */
 213 int drm_authmagic(struct inode *inode, struct file *filp,
 214                    unsigned int cmd, unsigned long arg)
 215 {
 216         drm_file_t         *priv    = filp->private_data;
 217         drm_device_t       *dev     = priv->head->dev;
 218         drm_auth_t         auth;
 219         drm_file_t         *file;
 220
 221         if (copy_from_user(&auth, (drm_auth_t __user *)arg, sizeof(auth)))
 222                 return -EFAULT;
 223         DRM_DEBUG("%u\n", auth.magic);
 224         if ((file = drm_find_file(dev, auth.magic))) {
 225                 file->authenticated = 1;
 226                 drm_remove_magic(dev, auth.magic);
 227                 return 0;
 228         }
 229         return -EINVAL;
 230 }