blob: 0102dc788608ec0060cf2fe1666e058c2d2d8076 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/drivers/char/raw.c
3 *
4 * Front-end raw character devices. These can be bound to any block
5 * devices to provide genuine Unix raw character device semantics.
6 *
7 * We reserve minor number 0 for a control interface. ioctl()s on this
8 * device are used to bind the other minor numbers to block devices.
9 */
10
11#include <linux/init.h>
12#include <linux/fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/major.h>
14#include <linux/blkdev.h>
15#include <linux/module.h>
16#include <linux/raw.h>
17#include <linux/capability.h>
18#include <linux/uio.h>
19#include <linux/cdev.h>
20#include <linux/device.h>
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080021#include <linux/mutex.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090022#include <linux/gfp.h>
Al Viroc4a04722009-08-24 22:42:56 +000023#include <linux/compat.h>
Jan Kara0078bff2011-04-29 00:24:29 +020024#include <linux/vmalloc.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
26#include <asm/uaccess.h>
27
28struct raw_device_data {
29 struct block_device *binding;
30 int inuse;
31};
32
gregkh@suse.deca8eca62005-03-23 09:53:09 -080033static struct class *raw_class;
Jan Kara0078bff2011-04-29 00:24:29 +020034static struct raw_device_data *raw_devices;
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080035static DEFINE_MUTEX(raw_mutex);
Arjan van de Ven62322d22006-07-03 00:24:21 -070036static const struct file_operations raw_ctl_fops; /* forward declaration */
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
Jan Kara0078bff2011-04-29 00:24:29 +020038static int max_raw_minors = MAX_RAW_MINORS;
39
40module_param(max_raw_minors, int, 0);
41MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)");
42
Linus Torvalds1da177e2005-04-16 15:20:36 -070043/*
44 * Open/close code for raw IO.
45 *
46 * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
47 * point at the blockdev's address_space and set the file handle to use
48 * O_DIRECT.
49 *
50 * Set the device's soft blocksize to the minimum possible. This gives the
51 * finest possible alignment and has no adverse impact on performance.
52 */
53static int raw_open(struct inode *inode, struct file *filp)
54{
55 const int minor = iminor(inode);
56 struct block_device *bdev;
57 int err;
58
59 if (minor == 0) { /* It is the control device */
60 filp->f_op = &raw_ctl_fops;
61 return 0;
62 }
63
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080064 mutex_lock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070065
66 /*
67 * All we need to do on open is check that the device is bound.
68 */
69 bdev = raw_devices[minor].binding;
70 err = -ENODEV;
71 if (!bdev)
72 goto out;
73 igrab(bdev->bd_inode);
Tejun Heoe525fd82010-11-13 11:55:17 +010074 err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 if (err)
76 goto out;
Martin K. Petersene1defc42009-05-22 17:17:49 -040077 err = set_blocksize(bdev, bdev_logical_block_size(bdev));
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 if (err)
Tejun Heoe525fd82010-11-13 11:55:17 +010079 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 filp->f_flags |= O_DIRECT;
81 filp->f_mapping = bdev->bd_inode->i_mapping;
82 if (++raw_devices[minor].inuse == 1)
Al Viro496ad9a2013-01-23 17:07:38 -050083 file_inode(filp)->i_mapping =
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 bdev->bd_inode->i_mapping;
85 filp->private_data = bdev;
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080086 mutex_unlock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 return 0;
88
Linus Torvalds1da177e2005-04-16 15:20:36 -070089out1:
Tejun Heoe525fd82010-11-13 11:55:17 +010090 blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
Linus Torvalds1da177e2005-04-16 15:20:36 -070091out:
Arjan van de Ven8ed965d2006-03-23 03:00:21 -080092 mutex_unlock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 return err;
94}
95
96/*
97 * When the final fd which refers to this character-special node is closed, we
98 * make its ->mapping point back at its own i_data.
99 */
100static int raw_release(struct inode *inode, struct file *filp)
101{
102 const int minor= iminor(inode);
103 struct block_device *bdev;
104
Arjan van de Ven8ed965d2006-03-23 03:00:21 -0800105 mutex_lock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 bdev = raw_devices[minor].binding;
107 if (--raw_devices[minor].inuse == 0) {
108 /* Here inode->i_mapping == bdev->bd_inode->i_mapping */
109 inode->i_mapping = &inode->i_data;
110 inode->i_mapping->backing_dev_info = &default_backing_dev_info;
111 }
Arjan van de Ven8ed965d2006-03-23 03:00:21 -0800112 mutex_unlock(&raw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113
Tejun Heoe525fd82010-11-13 11:55:17 +0100114 blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 return 0;
116}
117
118/*
119 * Forward ioctls to the underlying block device.
120 */
Arnd Bergmann55929332010-04-27 00:24:05 +0200121static long
122raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123{
124 struct block_device *bdev = filp->private_data;
Al Viroc4a04722009-08-24 22:42:56 +0000125 return blkdev_ioctl(bdev, 0, command, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126}
127
Al Viroc4a04722009-08-24 22:42:56 +0000128static int bind_set(int number, u64 major, u64 minor)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129{
Al Viroc4a04722009-08-24 22:42:56 +0000130 dev_t dev = MKDEV(major, minor);
131 struct raw_device_data *rawdev;
132 int err = 0;
133
Jan Kara0078bff2011-04-29 00:24:29 +0200134 if (number <= 0 || number >= max_raw_minors)
Al Viroc4a04722009-08-24 22:42:56 +0000135 return -EINVAL;
136
137 if (MAJOR(dev) != major || MINOR(dev) != minor)
138 return -EINVAL;
139
140 rawdev = &raw_devices[number];
141
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;
158
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;
186}
187
188static int bind_get(int number, dev_t *dev)
189{
190 struct raw_device_data *rawdev;
191 struct block_device *bdev;
192
Paul Bolle5bbb2ae2014-02-04 23:23:12 +0100193 if (number <= 0 || number >= max_raw_minors)
Al Viroc4a04722009-08-24 22:42:56 +0000194 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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203}
204
205/*
206 * Deal with ioctls against the raw-device control interface, to bind
207 * and unbind other raw devices.
208 */
Arnd Bergmann55929332010-04-27 00:24:05 +0200209static long raw_ctl_ioctl(struct file *filp, unsigned int command,
210 unsigned long arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211{
212 struct raw_config_request rq;
Al Viroc4a04722009-08-24 22:42:56 +0000213 dev_t dev;
214 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215
216 switch (command) {
217 case RAW_SETBIND:
Al Viroc4a04722009-08-24 22:42:56 +0000218 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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 case RAW_GETBIND:
Al Viroc4a04722009-08-24 22:42:56 +0000224 if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
225 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226
Al Viroc4a04722009-08-24 22:42:56 +0000227 err = bind_get(rq.raw_minor, &dev);
228 if (err)
229 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230
Al Viroc4a04722009-08-24 22:42:56 +0000231 rq.block_major = MAJOR(dev);
232 rq.block_minor = MINOR(dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233
Al Viroc4a04722009-08-24 22:42:56 +0000234 if (copy_to_user((void __user *)arg, &rq, sizeof(rq)))
235 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236
Al Viroc4a04722009-08-24 22:42:56 +0000237 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 }
Al Viroc4a04722009-08-24 22:42:56 +0000239
240 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241}
242
Al Viroc4a04722009-08-24 22:42:56 +0000243#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;
283}
284#endif
285
Arjan van de Ven62322d22006-07-03 00:24:21 -0700286static const struct file_operations raw_fops = {
Al Viroaad4f8b2014-04-02 14:33:16 -0400287 .read = new_sync_read,
288 .read_iter = generic_file_read_iter,
Al Viro1456c0a2014-04-03 03:21:50 -0400289 .write = new_sync_write,
290 .write_iter = blkdev_write_iter,
Arnd Bergmann55929332010-04-27 00:24:05 +0200291 .fsync = blkdev_fsync,
292 .open = raw_open,
293 .release = raw_release,
294 .unlocked_ioctl = raw_ioctl,
Arnd Bergmanncb3b9cf2010-07-06 23:03:55 +0200295 .llseek = default_llseek,
Arnd Bergmann55929332010-04-27 00:24:05 +0200296 .owner = THIS_MODULE,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297};
298
Arjan van de Ven62322d22006-07-03 00:24:21 -0700299static const struct file_operations raw_ctl_fops = {
Arnd Bergmann55929332010-04-27 00:24:05 +0200300 .unlocked_ioctl = raw_ctl_ioctl,
Al Viroc4a04722009-08-24 22:42:56 +0000301#ifdef CONFIG_COMPAT
302 .compat_ioctl = raw_ctl_compat_ioctl,
303#endif
Arnd Bergmann55929332010-04-27 00:24:05 +0200304 .open = raw_open,
305 .owner = THIS_MODULE,
Arnd Bergmanncb3b9cf2010-07-06 23:03:55 +0200306 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307};
308
Greg Kroah-Hartman7e7654a2007-09-12 15:06:57 -0700309static struct cdev raw_cdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310
Al Viro2c9ede52011-07-23 20:24:48 -0400311static char *raw_devnode(struct device *dev, umode_t *mode)
Kay Sievers6fd46932009-04-30 15:23:42 +0200312{
313 return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
314}
315
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316static int __init raw_init(void)
317{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 dev_t dev = MKDEV(RAW_MAJOR, 0);
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700319 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
Jan Kara0078bff2011-04-29 00:24:29 +0200321 if (max_raw_minors < 1 || max_raw_minors > 65536) {
322 printk(KERN_WARNING "raw: invalid max_raw_minors (must be"
323 " between 1 and 65536), using %d\n", MAX_RAW_MINORS);
324 max_raw_minors = MAX_RAW_MINORS;
325 }
326
Joe Perches8e03bd62011-05-28 10:36:25 -0700327 raw_devices = vzalloc(sizeof(struct raw_device_data) * max_raw_minors);
Jan Kara0078bff2011-04-29 00:24:29 +0200328 if (!raw_devices) {
329 printk(KERN_ERR "Not enough memory for raw device structures\n");
330 ret = -ENOMEM;
331 goto error;
332 }
Jan Kara0078bff2011-04-29 00:24:29 +0200333
334 ret = register_chrdev_region(dev, max_raw_minors, "raw");
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700335 if (ret)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 goto error;
337
338 cdev_init(&raw_cdev, &raw_fops);
Jan Kara0078bff2011-04-29 00:24:29 +0200339 ret = cdev_add(&raw_cdev, dev, max_raw_minors);
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700340 if (ret) {
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700341 goto error_region;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 }
343
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800344 raw_class = class_create(THIS_MODULE, "raw");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 if (IS_ERR(raw_class)) {
346 printk(KERN_ERR "Error creating raw class.\n");
347 cdev_del(&raw_cdev);
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700348 ret = PTR_ERR(raw_class);
349 goto error_region;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 }
Kay Sieverse454cea2009-09-18 23:01:12 +0200351 raw_class->devnode = raw_devnode;
Greg Kroah-Hartman03457cd2008-07-21 20:03:34 -0700352 device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 return 0;
355
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700356error_region:
Jan Kara0078bff2011-04-29 00:24:29 +0200357 unregister_chrdev_region(dev, max_raw_minors);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358error:
Jan Kara0078bff2011-04-29 00:24:29 +0200359 vfree(raw_devices);
Rolf Eike Beer3e26a422006-09-29 02:00:46 -0700360 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361}
362
363static void __exit raw_exit(void)
364{
Greg Kroah-Hartman38ca6c32006-08-07 22:19:37 -0700365 device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800366 class_destroy(raw_class);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 cdev_del(&raw_cdev);
Jan Kara0078bff2011-04-29 00:24:29 +0200368 unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), max_raw_minors);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369}
370
371module_init(raw_init);
372module_exit(raw_exit);
373MODULE_LICENSE("GPL");