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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 */
47static 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 */
62static 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 */
90static 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 */
127static 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 */
173int 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 */
213int 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}