Merge tag 'selinux-pr-20190726' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-2.6-block.git] / drivers / char / raw.c
CommitLineData
09c434b8 1// SPDX-License-Identifier: GPL-2.0-only
1da177e4
LT
2/*
3 * linux/drivers/char/raw.c
4 *
5 * Front-end raw character devices. These can be bound to any block
6 * devices to provide genuine Unix raw character device semantics.
7 *
8 * We reserve minor number 0 for a control interface. ioctl()s on this
9 * device are used to bind the other minor numbers to block devices.
10 */
11
12#include <linux/init.h>
13#include <linux/fs.h>
1da177e4
LT
14#include <linux/major.h>
15#include <linux/blkdev.h>
66114cad 16#include <linux/backing-dev.h>
1da177e4
LT
17#include <linux/module.h>
18#include <linux/raw.h>
19#include <linux/capability.h>
20#include <linux/uio.h>
21#include <linux/cdev.h>
22#include <linux/device.h>
8ed965d6 23#include <linux/mutex.h>
5a0e3ad6 24#include <linux/gfp.h>
c4a04727 25#include <linux/compat.h>
0078bff5 26#include <linux/vmalloc.h>
1da177e4 27
7c0f6ba6 28#include <linux/uaccess.h>
1da177e4
LT
29
30struct raw_device_data {
31 struct block_device *binding;
32 int inuse;
33};
34
ca8eca68 35static struct class *raw_class;
0078bff5 36static struct raw_device_data *raw_devices;
8ed965d6 37static DEFINE_MUTEX(raw_mutex);
62322d25 38static const struct file_operations raw_ctl_fops; /* forward declaration */
1da177e4 39
0078bff5
JK
40static int max_raw_minors = MAX_RAW_MINORS;
41
42module_param(max_raw_minors, int, 0);
43MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)");
44
1da177e4
LT
45/*
46 * Open/close code for raw IO.
47 *
48 * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
49 * point at the blockdev's address_space and set the file handle to use
50 * O_DIRECT.
51 *
52 * Set the device's soft blocksize to the minimum possible. This gives the
53 * finest possible alignment and has no adverse impact on performance.
54 */
55static int raw_open(struct inode *inode, struct file *filp)
56{
57 const int minor = iminor(inode);
58 struct block_device *bdev;
59 int err;
60
61 if (minor == 0) { /* It is the control device */
62 filp->f_op = &raw_ctl_fops;
63 return 0;
64 }
65
8ed965d6 66 mutex_lock(&raw_mutex);
1da177e4
LT
67
68 /*
69 * All we need to do on open is check that the device is bound.
70 */
71 bdev = raw_devices[minor].binding;
72 err = -ENODEV;
73 if (!bdev)
74 goto out;
ed8a9d2c 75 bdgrab(bdev);
e525fd89 76 err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open);
1da177e4
LT
77 if (err)
78 goto out;
e1defc4f 79 err = set_blocksize(bdev, bdev_logical_block_size(bdev));
1da177e4 80 if (err)
e525fd89 81 goto out1;
1da177e4
LT
82 filp->f_flags |= O_DIRECT;
83 filp->f_mapping = bdev->bd_inode->i_mapping;
84 if (++raw_devices[minor].inuse == 1)
496ad9aa 85 file_inode(filp)->i_mapping =
1da177e4
LT
86 bdev->bd_inode->i_mapping;
87 filp->private_data = bdev;
8ed965d6 88 mutex_unlock(&raw_mutex);
1da177e4
LT
89 return 0;
90
1da177e4 91out1:
e525fd89 92 blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
1da177e4 93out:
8ed965d6 94 mutex_unlock(&raw_mutex);
1da177e4
LT
95 return err;
96}
97
98/*
99 * When the final fd which refers to this character-special node is closed, we
100 * make its ->mapping point back at its own i_data.
101 */
102static int raw_release(struct inode *inode, struct file *filp)
103{
104 const int minor= iminor(inode);
105 struct block_device *bdev;
106
8ed965d6 107 mutex_lock(&raw_mutex);
1da177e4 108 bdev = raw_devices[minor].binding;
b83ae6d4 109 if (--raw_devices[minor].inuse == 0)
1da177e4
LT
110 /* Here inode->i_mapping == bdev->bd_inode->i_mapping */
111 inode->i_mapping = &inode->i_data;
8ed965d6 112 mutex_unlock(&raw_mutex);
1da177e4 113
e525fd89 114 blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
1da177e4
LT
115 return 0;
116}
117
118/*
119 * Forward ioctls to the underlying block device.
120 */
55929332
AB
121static long
122raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
1da177e4
LT
123{
124 struct block_device *bdev = filp->private_data;
c4a04727
AV
125 return blkdev_ioctl(bdev, 0, command, arg);
126}
127
128static int bind_set(int number, u64 major, u64 minor)
129{
130 dev_t dev = MKDEV(major, minor);
131 struct raw_device_data *rawdev;
132 int err = 0;
133
0078bff5 134 if (number <= 0 || number >= max_raw_minors)
c4a04727
AV
135 return -EINVAL;
136
137 if (MAJOR(dev) != major || MINOR(dev) != minor)
138 return -EINVAL;
139
140 rawdev = &raw_devices[number];
1da177e4 141
c4a04727
AV
142 /*
143 * This is like making block devices, so demand the
144 * same capability
145 */
146 if (!capable(CAP_SYS_ADMIN))
147 return -EPERM;
148
149 /*
150 * For now, we don't need to check that the underlying
151 * block device is present or not: we can do that when
152 * the raw device is opened. Just check that the
153 * major/minor numbers make sense.
154 */
155
156 if (MAJOR(dev) == 0 && dev != 0)
157 return -EINVAL;
55929332 158
c4a04727
AV
159 mutex_lock(&raw_mutex);
160 if (rawdev->inuse) {
161 mutex_unlock(&raw_mutex);
162 return -EBUSY;
163 }
164 if (rawdev->binding) {
165 bdput(rawdev->binding);
166 module_put(THIS_MODULE);
167 }
168 if (!dev) {
169 /* unbind */
170 rawdev->binding = NULL;
171 device_destroy(raw_class, MKDEV(RAW_MAJOR, number));
172 } else {
173 rawdev->binding = bdget(dev);
174 if (rawdev->binding == NULL) {
175 err = -ENOMEM;
176 } else {
177 dev_t raw = MKDEV(RAW_MAJOR, number);
178 __module_get(THIS_MODULE);
179 device_destroy(raw_class, raw);
180 device_create(raw_class, NULL, raw, NULL,
181 "raw%d", number);
182 }
183 }
184 mutex_unlock(&raw_mutex);
185 return err;
1da177e4
LT
186}
187
c4a04727 188static int bind_get(int number, dev_t *dev)
1da177e4 189{
c4a04727
AV
190 struct raw_device_data *rawdev;
191 struct block_device *bdev;
192
5bbb2ae3 193 if (number <= 0 || number >= max_raw_minors)
c4a04727
AV
194 return -EINVAL;
195
196 rawdev = &raw_devices[number];
197
198 mutex_lock(&raw_mutex);
199 bdev = rawdev->binding;
200 *dev = bdev ? bdev->bd_dev : 0;
201 mutex_unlock(&raw_mutex);
202 return 0;
1da177e4
LT
203}
204
205/*
206 * Deal with ioctls against the raw-device control interface, to bind
207 * and unbind other raw devices.
208 */
55929332
AB
209static long raw_ctl_ioctl(struct file *filp, unsigned int command,
210 unsigned long arg)
1da177e4
LT
211{
212 struct raw_config_request rq;
c4a04727
AV
213 dev_t dev;
214 int err;
1da177e4
LT
215
216 switch (command) {
217 case RAW_SETBIND:
c4a04727
AV
218 if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
219 return -EFAULT;
220
221 return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
222
1da177e4 223 case RAW_GETBIND:
c4a04727
AV
224 if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
225 return -EFAULT;
1da177e4 226
c4a04727
AV
227 err = bind_get(rq.raw_minor, &dev);
228 if (err)
229 return err;
1da177e4 230
c4a04727
AV
231 rq.block_major = MAJOR(dev);
232 rq.block_minor = MINOR(dev);
1da177e4 233
c4a04727
AV
234 if (copy_to_user((void __user *)arg, &rq, sizeof(rq)))
235 return -EFAULT;
236
237 return 0;
1da177e4 238 }
c4a04727
AV
239
240 return -EINVAL;
241}
242
243#ifdef CONFIG_COMPAT
244struct raw32_config_request {
245 compat_int_t raw_minor;
246 compat_u64 block_major;
247 compat_u64 block_minor;
248};
249
250static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,
251 unsigned long arg)
252{
253 struct raw32_config_request __user *user_req = compat_ptr(arg);
254 struct raw32_config_request rq;
255 dev_t dev;
256 int err = 0;
257
258 switch (cmd) {
259 case RAW_SETBIND:
260 if (copy_from_user(&rq, user_req, sizeof(rq)))
261 return -EFAULT;
262
263 return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
264
265 case RAW_GETBIND:
266 if (copy_from_user(&rq, user_req, sizeof(rq)))
267 return -EFAULT;
268
269 err = bind_get(rq.raw_minor, &dev);
270 if (err)
271 return err;
272
273 rq.block_major = MAJOR(dev);
274 rq.block_minor = MINOR(dev);
275
276 if (copy_to_user(user_req, &rq, sizeof(rq)))
277 return -EFAULT;
278
279 return 0;
280 }
281
282 return -EINVAL;
1da177e4 283}
c4a04727 284#endif
1da177e4 285
62322d25 286static const struct file_operations raw_fops = {
b2de525f 287 .read_iter = blkdev_read_iter,
1456c0a8 288 .write_iter = blkdev_write_iter,
55929332
AB
289 .fsync = blkdev_fsync,
290 .open = raw_open,
291 .release = raw_release,
292 .unlocked_ioctl = raw_ioctl,
cb3b9cf8 293 .llseek = default_llseek,
55929332 294 .owner = THIS_MODULE,
1da177e4
LT
295};
296
62322d25 297static const struct file_operations raw_ctl_fops = {
55929332 298 .unlocked_ioctl = raw_ctl_ioctl,
c4a04727
AV
299#ifdef CONFIG_COMPAT
300 .compat_ioctl = raw_ctl_compat_ioctl,
301#endif
55929332
AB
302 .open = raw_open,
303 .owner = THIS_MODULE,
cb3b9cf8 304 .llseek = noop_llseek,
1da177e4
LT
305};
306
7e7654a9 307static struct cdev raw_cdev;
1da177e4 308
2c9ede55 309static char *raw_devnode(struct device *dev, umode_t *mode)
6fd46933
KS
310{
311 return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
312}
313
1da177e4
LT
314static int __init raw_init(void)
315{
1da177e4 316 dev_t dev = MKDEV(RAW_MAJOR, 0);
3e26a423 317 int ret;
1da177e4 318
0078bff5
JK
319 if (max_raw_minors < 1 || max_raw_minors > 65536) {
320 printk(KERN_WARNING "raw: invalid max_raw_minors (must be"
321 " between 1 and 65536), using %d\n", MAX_RAW_MINORS);
322 max_raw_minors = MAX_RAW_MINORS;
323 }
324
fad953ce
KC
325 raw_devices = vzalloc(array_size(max_raw_minors,
326 sizeof(struct raw_device_data)));
0078bff5
JK
327 if (!raw_devices) {
328 printk(KERN_ERR "Not enough memory for raw device structures\n");
329 ret = -ENOMEM;
330 goto error;
331 }
0078bff5
JK
332
333 ret = register_chrdev_region(dev, max_raw_minors, "raw");
3e26a423 334 if (ret)
1da177e4
LT
335 goto error;
336
337 cdev_init(&raw_cdev, &raw_fops);
0078bff5 338 ret = cdev_add(&raw_cdev, dev, max_raw_minors);
202cdb6f 339 if (ret)
3e26a423 340 goto error_region;
ca8eca68 341 raw_class = class_create(THIS_MODULE, "raw");
1da177e4
LT
342 if (IS_ERR(raw_class)) {
343 printk(KERN_ERR "Error creating raw class.\n");
344 cdev_del(&raw_cdev);
3e26a423
REB
345 ret = PTR_ERR(raw_class);
346 goto error_region;
1da177e4 347 }
e454cea2 348 raw_class->devnode = raw_devnode;
03457cd4 349 device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
1da177e4 350
1da177e4
LT
351 return 0;
352
3e26a423 353error_region:
0078bff5 354 unregister_chrdev_region(dev, max_raw_minors);
1da177e4 355error:
0078bff5 356 vfree(raw_devices);
3e26a423 357 return ret;
1da177e4
LT
358}
359
360static void __exit raw_exit(void)
361{
38ca6c34 362 device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
ca8eca68 363 class_destroy(raw_class);
1da177e4 364 cdev_del(&raw_cdev);
0078bff5 365 unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), max_raw_minors);
1da177e4
LT
366}
367
368module_init(raw_init);
369module_exit(raw_exit);
370MODULE_LICENSE("GPL");