Commit | Line | Data |
---|---|---|
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> |
0078bff5 | 24 | #include <linux/vmalloc.h> |
1da177e4 LT |
25 | |
26 | #include <asm/uaccess.h> | |
27 | ||
28 | struct raw_device_data { | |
29 | struct block_device *binding; | |
30 | int inuse; | |
31 | }; | |
32 | ||
ca8eca68 | 33 | static struct class *raw_class; |
0078bff5 | 34 | static struct raw_device_data *raw_devices; |
8ed965d6 | 35 | static DEFINE_MUTEX(raw_mutex); |
62322d25 | 36 | static const struct file_operations raw_ctl_fops; /* forward declaration */ |
1da177e4 | 37 | |
0078bff5 JK |
38 | static int max_raw_minors = MAX_RAW_MINORS; |
39 | ||
40 | module_param(max_raw_minors, int, 0); | |
41 | MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)"); | |
42 | ||
1da177e4 LT |
43 | /* |
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 | */ | |
53 | static 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 | ||
8ed965d6 | 64 | mutex_lock(&raw_mutex); |
1da177e4 LT |
65 | |
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); | |
e525fd89 | 74 | err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open); |
1da177e4 LT |
75 | if (err) |
76 | goto out; | |
e1defc4f | 77 | err = set_blocksize(bdev, bdev_logical_block_size(bdev)); |
1da177e4 | 78 | if (err) |
e525fd89 | 79 | goto out1; |
1da177e4 LT |
80 | filp->f_flags |= O_DIRECT; |
81 | filp->f_mapping = bdev->bd_inode->i_mapping; | |
82 | if (++raw_devices[minor].inuse == 1) | |
496ad9aa | 83 | file_inode(filp)->i_mapping = |
1da177e4 LT |
84 | bdev->bd_inode->i_mapping; |
85 | filp->private_data = bdev; | |
8ed965d6 | 86 | mutex_unlock(&raw_mutex); |
1da177e4 LT |
87 | return 0; |
88 | ||
1da177e4 | 89 | out1: |
e525fd89 | 90 | blkdev_put(bdev, filp->f_mode | FMODE_EXCL); |
1da177e4 | 91 | out: |
8ed965d6 | 92 | mutex_unlock(&raw_mutex); |
1da177e4 LT |
93 | 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 | */ | |
100 | static int raw_release(struct inode *inode, struct file *filp) | |
101 | { | |
102 | const int minor= iminor(inode); | |
103 | struct block_device *bdev; | |
104 | ||
8ed965d6 | 105 | mutex_lock(&raw_mutex); |
1da177e4 | 106 | bdev = raw_devices[minor].binding; |
b83ae6d4 | 107 | if (--raw_devices[minor].inuse == 0) |
1da177e4 LT |
108 | /* Here inode->i_mapping == bdev->bd_inode->i_mapping */ |
109 | inode->i_mapping = &inode->i_data; | |
8ed965d6 | 110 | mutex_unlock(&raw_mutex); |
1da177e4 | 111 | |
e525fd89 | 112 | blkdev_put(bdev, filp->f_mode | FMODE_EXCL); |
1da177e4 LT |
113 | return 0; |
114 | } | |
115 | ||
116 | /* | |
117 | * Forward ioctls to the underlying block device. | |
118 | */ | |
55929332 AB |
119 | static long |
120 | raw_ioctl(struct file *filp, unsigned int command, unsigned long arg) | |
1da177e4 LT |
121 | { |
122 | struct block_device *bdev = filp->private_data; | |
c4a04727 AV |
123 | return blkdev_ioctl(bdev, 0, command, arg); |
124 | } | |
125 | ||
126 | static int bind_set(int number, u64 major, u64 minor) | |
127 | { | |
128 | dev_t dev = MKDEV(major, minor); | |
129 | struct raw_device_data *rawdev; | |
130 | int err = 0; | |
131 | ||
0078bff5 | 132 | if (number <= 0 || number >= max_raw_minors) |
c4a04727 AV |
133 | return -EINVAL; |
134 | ||
135 | if (MAJOR(dev) != major || MINOR(dev) != minor) | |
136 | return -EINVAL; | |
137 | ||
138 | rawdev = &raw_devices[number]; | |
1da177e4 | 139 | |
c4a04727 AV |
140 | /* |
141 | * This is like making block devices, so demand the | |
142 | * same capability | |
143 | */ | |
144 | if (!capable(CAP_SYS_ADMIN)) | |
145 | return -EPERM; | |
146 | ||
147 | /* | |
148 | * For now, we don't need to check that the underlying | |
149 | * block device is present or not: we can do that when | |
150 | * the raw device is opened. Just check that the | |
151 | * major/minor numbers make sense. | |
152 | */ | |
153 | ||
154 | if (MAJOR(dev) == 0 && dev != 0) | |
155 | return -EINVAL; | |
55929332 | 156 | |
c4a04727 AV |
157 | mutex_lock(&raw_mutex); |
158 | if (rawdev->inuse) { | |
159 | mutex_unlock(&raw_mutex); | |
160 | return -EBUSY; | |
161 | } | |
162 | if (rawdev->binding) { | |
163 | bdput(rawdev->binding); | |
164 | module_put(THIS_MODULE); | |
165 | } | |
166 | if (!dev) { | |
167 | /* unbind */ | |
168 | rawdev->binding = NULL; | |
169 | device_destroy(raw_class, MKDEV(RAW_MAJOR, number)); | |
170 | } else { | |
171 | rawdev->binding = bdget(dev); | |
172 | if (rawdev->binding == NULL) { | |
173 | err = -ENOMEM; | |
174 | } else { | |
175 | dev_t raw = MKDEV(RAW_MAJOR, number); | |
176 | __module_get(THIS_MODULE); | |
177 | device_destroy(raw_class, raw); | |
178 | device_create(raw_class, NULL, raw, NULL, | |
179 | "raw%d", number); | |
180 | } | |
181 | } | |
182 | mutex_unlock(&raw_mutex); | |
183 | return err; | |
1da177e4 LT |
184 | } |
185 | ||
c4a04727 | 186 | static int bind_get(int number, dev_t *dev) |
1da177e4 | 187 | { |
c4a04727 AV |
188 | struct raw_device_data *rawdev; |
189 | struct block_device *bdev; | |
190 | ||
5bbb2ae3 | 191 | if (number <= 0 || number >= max_raw_minors) |
c4a04727 AV |
192 | return -EINVAL; |
193 | ||
194 | rawdev = &raw_devices[number]; | |
195 | ||
196 | mutex_lock(&raw_mutex); | |
197 | bdev = rawdev->binding; | |
198 | *dev = bdev ? bdev->bd_dev : 0; | |
199 | mutex_unlock(&raw_mutex); | |
200 | return 0; | |
1da177e4 LT |
201 | } |
202 | ||
203 | /* | |
204 | * Deal with ioctls against the raw-device control interface, to bind | |
205 | * and unbind other raw devices. | |
206 | */ | |
55929332 AB |
207 | static long raw_ctl_ioctl(struct file *filp, unsigned int command, |
208 | unsigned long arg) | |
1da177e4 LT |
209 | { |
210 | struct raw_config_request rq; | |
c4a04727 AV |
211 | dev_t dev; |
212 | int err; | |
1da177e4 LT |
213 | |
214 | switch (command) { | |
215 | case RAW_SETBIND: | |
c4a04727 AV |
216 | if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) |
217 | return -EFAULT; | |
218 | ||
219 | return bind_set(rq.raw_minor, rq.block_major, rq.block_minor); | |
220 | ||
1da177e4 | 221 | case RAW_GETBIND: |
c4a04727 AV |
222 | if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) |
223 | return -EFAULT; | |
1da177e4 | 224 | |
c4a04727 AV |
225 | err = bind_get(rq.raw_minor, &dev); |
226 | if (err) | |
227 | return err; | |
1da177e4 | 228 | |
c4a04727 AV |
229 | rq.block_major = MAJOR(dev); |
230 | rq.block_minor = MINOR(dev); | |
1da177e4 | 231 | |
c4a04727 AV |
232 | if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) |
233 | return -EFAULT; | |
234 | ||
235 | return 0; | |
1da177e4 | 236 | } |
c4a04727 AV |
237 | |
238 | return -EINVAL; | |
239 | } | |
240 | ||
241 | #ifdef CONFIG_COMPAT | |
242 | struct raw32_config_request { | |
243 | compat_int_t raw_minor; | |
244 | compat_u64 block_major; | |
245 | compat_u64 block_minor; | |
246 | }; | |
247 | ||
248 | static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd, | |
249 | unsigned long arg) | |
250 | { | |
251 | struct raw32_config_request __user *user_req = compat_ptr(arg); | |
252 | struct raw32_config_request rq; | |
253 | dev_t dev; | |
254 | int err = 0; | |
255 | ||
256 | switch (cmd) { | |
257 | case RAW_SETBIND: | |
258 | if (copy_from_user(&rq, user_req, sizeof(rq))) | |
259 | return -EFAULT; | |
260 | ||
261 | return bind_set(rq.raw_minor, rq.block_major, rq.block_minor); | |
262 | ||
263 | case RAW_GETBIND: | |
264 | if (copy_from_user(&rq, user_req, sizeof(rq))) | |
265 | return -EFAULT; | |
266 | ||
267 | err = bind_get(rq.raw_minor, &dev); | |
268 | if (err) | |
269 | return err; | |
270 | ||
271 | rq.block_major = MAJOR(dev); | |
272 | rq.block_minor = MINOR(dev); | |
273 | ||
274 | if (copy_to_user(user_req, &rq, sizeof(rq))) | |
275 | return -EFAULT; | |
276 | ||
277 | return 0; | |
278 | } | |
279 | ||
280 | return -EINVAL; | |
1da177e4 | 281 | } |
c4a04727 | 282 | #endif |
1da177e4 | 283 | |
62322d25 | 284 | static const struct file_operations raw_fops = { |
aad4f8bb | 285 | .read = new_sync_read, |
b2de525f | 286 | .read_iter = blkdev_read_iter, |
1456c0a8 AV |
287 | .write = new_sync_write, |
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 | 297 | static 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 | 307 | static struct cdev raw_cdev; |
1da177e4 | 308 | |
2c9ede55 | 309 | static 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 |
314 | static 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 | ||
8e03bd65 | 325 | raw_devices = vzalloc(sizeof(struct raw_device_data) * max_raw_minors); |
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); |
3e26a423 | 338 | if (ret) { |
3e26a423 | 339 | goto error_region; |
1da177e4 LT |
340 | } |
341 | ||
ca8eca68 | 342 | raw_class = class_create(THIS_MODULE, "raw"); |
1da177e4 LT |
343 | if (IS_ERR(raw_class)) { |
344 | printk(KERN_ERR "Error creating raw class.\n"); | |
345 | cdev_del(&raw_cdev); | |
3e26a423 REB |
346 | ret = PTR_ERR(raw_class); |
347 | goto error_region; | |
1da177e4 | 348 | } |
e454cea2 | 349 | raw_class->devnode = raw_devnode; |
03457cd4 | 350 | device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl"); |
1da177e4 | 351 | |
1da177e4 LT |
352 | return 0; |
353 | ||
3e26a423 | 354 | error_region: |
0078bff5 | 355 | unregister_chrdev_region(dev, max_raw_minors); |
1da177e4 | 356 | error: |
0078bff5 | 357 | vfree(raw_devices); |
3e26a423 | 358 | return ret; |
1da177e4 LT |
359 | } |
360 | ||
361 | static void __exit raw_exit(void) | |
362 | { | |
38ca6c34 | 363 | device_destroy(raw_class, MKDEV(RAW_MAJOR, 0)); |
ca8eca68 | 364 | class_destroy(raw_class); |
1da177e4 | 365 | cdev_del(&raw_cdev); |
0078bff5 | 366 | unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), max_raw_minors); |
1da177e4 LT |
367 | } |
368 | ||
369 | module_init(raw_init); | |
370 | module_exit(raw_exit); | |
371 | MODULE_LICENSE("GPL"); |