Commit | Line | Data |
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1da177e4 LT |
1 | /* |
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> | |
1da177e4 LT |
13 | #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> | |
8ed965d6 | 21 | #include <linux/mutex.h> |
5a0e3ad6 | 22 | #include <linux/gfp.h> |
c4a04727 | 23 | #include <linux/compat.h> |
1da177e4 LT |
24 | |
25 | #include <asm/uaccess.h> | |
26 | ||
27 | struct raw_device_data { | |
28 | struct block_device *binding; | |
29 | int inuse; | |
30 | }; | |
31 | ||
ca8eca68 | 32 | static struct class *raw_class; |
1da177e4 | 33 | static struct raw_device_data raw_devices[MAX_RAW_MINORS]; |
8ed965d6 | 34 | static DEFINE_MUTEX(raw_mutex); |
62322d25 | 35 | static const struct file_operations raw_ctl_fops; /* forward declaration */ |
1da177e4 LT |
36 | |
37 | /* | |
38 | * Open/close code for raw IO. | |
39 | * | |
40 | * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to | |
41 | * point at the blockdev's address_space and set the file handle to use | |
42 | * O_DIRECT. | |
43 | * | |
44 | * Set the device's soft blocksize to the minimum possible. This gives the | |
45 | * finest possible alignment and has no adverse impact on performance. | |
46 | */ | |
47 | static int raw_open(struct inode *inode, struct file *filp) | |
48 | { | |
49 | const int minor = iminor(inode); | |
50 | struct block_device *bdev; | |
51 | int err; | |
52 | ||
53 | if (minor == 0) { /* It is the control device */ | |
54 | filp->f_op = &raw_ctl_fops; | |
55 | return 0; | |
56 | } | |
57 | ||
8ed965d6 | 58 | mutex_lock(&raw_mutex); |
1da177e4 LT |
59 | |
60 | /* | |
61 | * All we need to do on open is check that the device is bound. | |
62 | */ | |
63 | bdev = raw_devices[minor].binding; | |
64 | err = -ENODEV; | |
65 | if (!bdev) | |
66 | goto out; | |
67 | igrab(bdev->bd_inode); | |
e525fd89 | 68 | err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open); |
1da177e4 LT |
69 | if (err) |
70 | goto out; | |
e1defc4f | 71 | err = set_blocksize(bdev, bdev_logical_block_size(bdev)); |
1da177e4 | 72 | if (err) |
e525fd89 | 73 | goto out1; |
1da177e4 LT |
74 | filp->f_flags |= O_DIRECT; |
75 | filp->f_mapping = bdev->bd_inode->i_mapping; | |
76 | if (++raw_devices[minor].inuse == 1) | |
a7113a96 | 77 | filp->f_path.dentry->d_inode->i_mapping = |
1da177e4 LT |
78 | bdev->bd_inode->i_mapping; |
79 | filp->private_data = bdev; | |
8ed965d6 | 80 | mutex_unlock(&raw_mutex); |
1da177e4 LT |
81 | return 0; |
82 | ||
1da177e4 | 83 | out1: |
e525fd89 | 84 | blkdev_put(bdev, filp->f_mode | FMODE_EXCL); |
1da177e4 | 85 | out: |
8ed965d6 | 86 | mutex_unlock(&raw_mutex); |
1da177e4 LT |
87 | return err; |
88 | } | |
89 | ||
90 | /* | |
91 | * When the final fd which refers to this character-special node is closed, we | |
92 | * make its ->mapping point back at its own i_data. | |
93 | */ | |
94 | static int raw_release(struct inode *inode, struct file *filp) | |
95 | { | |
96 | const int minor= iminor(inode); | |
97 | struct block_device *bdev; | |
98 | ||
8ed965d6 | 99 | mutex_lock(&raw_mutex); |
1da177e4 LT |
100 | bdev = raw_devices[minor].binding; |
101 | if (--raw_devices[minor].inuse == 0) { | |
102 | /* Here inode->i_mapping == bdev->bd_inode->i_mapping */ | |
103 | inode->i_mapping = &inode->i_data; | |
104 | inode->i_mapping->backing_dev_info = &default_backing_dev_info; | |
105 | } | |
8ed965d6 | 106 | mutex_unlock(&raw_mutex); |
1da177e4 | 107 | |
e525fd89 | 108 | blkdev_put(bdev, filp->f_mode | FMODE_EXCL); |
1da177e4 LT |
109 | return 0; |
110 | } | |
111 | ||
112 | /* | |
113 | * Forward ioctls to the underlying block device. | |
114 | */ | |
55929332 AB |
115 | static long |
116 | raw_ioctl(struct file *filp, unsigned int command, unsigned long arg) | |
1da177e4 LT |
117 | { |
118 | struct block_device *bdev = filp->private_data; | |
c4a04727 AV |
119 | return blkdev_ioctl(bdev, 0, command, arg); |
120 | } | |
121 | ||
122 | static int bind_set(int number, u64 major, u64 minor) | |
123 | { | |
124 | dev_t dev = MKDEV(major, minor); | |
125 | struct raw_device_data *rawdev; | |
126 | int err = 0; | |
127 | ||
128 | if (number <= 0 || number >= MAX_RAW_MINORS) | |
129 | return -EINVAL; | |
130 | ||
131 | if (MAJOR(dev) != major || MINOR(dev) != minor) | |
132 | return -EINVAL; | |
133 | ||
134 | rawdev = &raw_devices[number]; | |
1da177e4 | 135 | |
c4a04727 AV |
136 | /* |
137 | * This is like making block devices, so demand the | |
138 | * same capability | |
139 | */ | |
140 | if (!capable(CAP_SYS_ADMIN)) | |
141 | return -EPERM; | |
142 | ||
143 | /* | |
144 | * For now, we don't need to check that the underlying | |
145 | * block device is present or not: we can do that when | |
146 | * the raw device is opened. Just check that the | |
147 | * major/minor numbers make sense. | |
148 | */ | |
149 | ||
150 | if (MAJOR(dev) == 0 && dev != 0) | |
151 | return -EINVAL; | |
55929332 | 152 | |
c4a04727 AV |
153 | mutex_lock(&raw_mutex); |
154 | if (rawdev->inuse) { | |
155 | mutex_unlock(&raw_mutex); | |
156 | return -EBUSY; | |
157 | } | |
158 | if (rawdev->binding) { | |
159 | bdput(rawdev->binding); | |
160 | module_put(THIS_MODULE); | |
161 | } | |
162 | if (!dev) { | |
163 | /* unbind */ | |
164 | rawdev->binding = NULL; | |
165 | device_destroy(raw_class, MKDEV(RAW_MAJOR, number)); | |
166 | } else { | |
167 | rawdev->binding = bdget(dev); | |
168 | if (rawdev->binding == NULL) { | |
169 | err = -ENOMEM; | |
170 | } else { | |
171 | dev_t raw = MKDEV(RAW_MAJOR, number); | |
172 | __module_get(THIS_MODULE); | |
173 | device_destroy(raw_class, raw); | |
174 | device_create(raw_class, NULL, raw, NULL, | |
175 | "raw%d", number); | |
176 | } | |
177 | } | |
178 | mutex_unlock(&raw_mutex); | |
179 | return err; | |
1da177e4 LT |
180 | } |
181 | ||
c4a04727 | 182 | static int bind_get(int number, dev_t *dev) |
1da177e4 | 183 | { |
c4a04727 AV |
184 | struct raw_device_data *rawdev; |
185 | struct block_device *bdev; | |
186 | ||
187 | if (number <= 0 || number >= MAX_RAW_MINORS) | |
188 | return -EINVAL; | |
189 | ||
190 | rawdev = &raw_devices[number]; | |
191 | ||
192 | mutex_lock(&raw_mutex); | |
193 | bdev = rawdev->binding; | |
194 | *dev = bdev ? bdev->bd_dev : 0; | |
195 | mutex_unlock(&raw_mutex); | |
196 | return 0; | |
1da177e4 LT |
197 | } |
198 | ||
199 | /* | |
200 | * Deal with ioctls against the raw-device control interface, to bind | |
201 | * and unbind other raw devices. | |
202 | */ | |
55929332 AB |
203 | static long raw_ctl_ioctl(struct file *filp, unsigned int command, |
204 | unsigned long arg) | |
1da177e4 LT |
205 | { |
206 | struct raw_config_request rq; | |
c4a04727 AV |
207 | dev_t dev; |
208 | int err; | |
1da177e4 LT |
209 | |
210 | switch (command) { | |
211 | case RAW_SETBIND: | |
c4a04727 AV |
212 | if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) |
213 | return -EFAULT; | |
214 | ||
215 | return bind_set(rq.raw_minor, rq.block_major, rq.block_minor); | |
216 | ||
1da177e4 | 217 | case RAW_GETBIND: |
c4a04727 AV |
218 | if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) |
219 | return -EFAULT; | |
1da177e4 | 220 | |
c4a04727 AV |
221 | err = bind_get(rq.raw_minor, &dev); |
222 | if (err) | |
223 | return err; | |
1da177e4 | 224 | |
c4a04727 AV |
225 | rq.block_major = MAJOR(dev); |
226 | rq.block_minor = MINOR(dev); | |
1da177e4 | 227 | |
c4a04727 AV |
228 | if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) |
229 | return -EFAULT; | |
230 | ||
231 | return 0; | |
1da177e4 | 232 | } |
c4a04727 AV |
233 | |
234 | return -EINVAL; | |
235 | } | |
236 | ||
237 | #ifdef CONFIG_COMPAT | |
238 | struct raw32_config_request { | |
239 | compat_int_t raw_minor; | |
240 | compat_u64 block_major; | |
241 | compat_u64 block_minor; | |
242 | }; | |
243 | ||
244 | static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd, | |
245 | unsigned long arg) | |
246 | { | |
247 | struct raw32_config_request __user *user_req = compat_ptr(arg); | |
248 | struct raw32_config_request rq; | |
249 | dev_t dev; | |
250 | int err = 0; | |
251 | ||
252 | switch (cmd) { | |
253 | case RAW_SETBIND: | |
254 | if (copy_from_user(&rq, user_req, sizeof(rq))) | |
255 | return -EFAULT; | |
256 | ||
257 | return bind_set(rq.raw_minor, rq.block_major, rq.block_minor); | |
258 | ||
259 | case RAW_GETBIND: | |
260 | if (copy_from_user(&rq, user_req, sizeof(rq))) | |
261 | return -EFAULT; | |
262 | ||
263 | err = bind_get(rq.raw_minor, &dev); | |
264 | if (err) | |
265 | return err; | |
266 | ||
267 | rq.block_major = MAJOR(dev); | |
268 | rq.block_minor = MINOR(dev); | |
269 | ||
270 | if (copy_to_user(user_req, &rq, sizeof(rq))) | |
271 | return -EFAULT; | |
272 | ||
273 | return 0; | |
274 | } | |
275 | ||
276 | return -EINVAL; | |
1da177e4 | 277 | } |
c4a04727 | 278 | #endif |
1da177e4 | 279 | |
62322d25 | 280 | static const struct file_operations raw_fops = { |
55929332 AB |
281 | .read = do_sync_read, |
282 | .aio_read = generic_file_aio_read, | |
283 | .write = do_sync_write, | |
284 | .aio_write = blkdev_aio_write, | |
285 | .fsync = blkdev_fsync, | |
286 | .open = raw_open, | |
287 | .release = raw_release, | |
288 | .unlocked_ioctl = raw_ioctl, | |
cb3b9cf8 | 289 | .llseek = default_llseek, |
55929332 | 290 | .owner = THIS_MODULE, |
1da177e4 LT |
291 | }; |
292 | ||
62322d25 | 293 | static const struct file_operations raw_ctl_fops = { |
55929332 | 294 | .unlocked_ioctl = raw_ctl_ioctl, |
c4a04727 AV |
295 | #ifdef CONFIG_COMPAT |
296 | .compat_ioctl = raw_ctl_compat_ioctl, | |
297 | #endif | |
55929332 AB |
298 | .open = raw_open, |
299 | .owner = THIS_MODULE, | |
cb3b9cf8 | 300 | .llseek = noop_llseek, |
1da177e4 LT |
301 | }; |
302 | ||
7e7654a9 | 303 | static struct cdev raw_cdev; |
1da177e4 | 304 | |
e454cea2 | 305 | static char *raw_devnode(struct device *dev, mode_t *mode) |
6fd46933 KS |
306 | { |
307 | return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev)); | |
308 | } | |
309 | ||
1da177e4 LT |
310 | static int __init raw_init(void) |
311 | { | |
1da177e4 | 312 | dev_t dev = MKDEV(RAW_MAJOR, 0); |
3e26a423 | 313 | int ret; |
1da177e4 | 314 | |
3e26a423 REB |
315 | ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw"); |
316 | if (ret) | |
1da177e4 LT |
317 | goto error; |
318 | ||
319 | cdev_init(&raw_cdev, &raw_fops); | |
3e26a423 REB |
320 | ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS); |
321 | if (ret) { | |
1da177e4 | 322 | kobject_put(&raw_cdev.kobj); |
3e26a423 | 323 | goto error_region; |
1da177e4 LT |
324 | } |
325 | ||
ca8eca68 | 326 | raw_class = class_create(THIS_MODULE, "raw"); |
1da177e4 LT |
327 | if (IS_ERR(raw_class)) { |
328 | printk(KERN_ERR "Error creating raw class.\n"); | |
329 | cdev_del(&raw_cdev); | |
3e26a423 REB |
330 | ret = PTR_ERR(raw_class); |
331 | goto error_region; | |
1da177e4 | 332 | } |
e454cea2 | 333 | raw_class->devnode = raw_devnode; |
03457cd4 | 334 | device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl"); |
1da177e4 | 335 | |
1da177e4 LT |
336 | return 0; |
337 | ||
3e26a423 REB |
338 | error_region: |
339 | unregister_chrdev_region(dev, MAX_RAW_MINORS); | |
1da177e4 | 340 | error: |
3e26a423 | 341 | return ret; |
1da177e4 LT |
342 | } |
343 | ||
344 | static void __exit raw_exit(void) | |
345 | { | |
38ca6c34 | 346 | device_destroy(raw_class, MKDEV(RAW_MAJOR, 0)); |
ca8eca68 | 347 | class_destroy(raw_class); |
1da177e4 LT |
348 | cdev_del(&raw_cdev); |
349 | unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS); | |
350 | } | |
351 | ||
352 | module_init(raw_init); | |
353 | module_exit(raw_exit); | |
354 | MODULE_LICENSE("GPL"); |