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