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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 | |
30 | struct raw_device_data { | |
31 | struct block_device *binding; | |
32 | int inuse; | |
33 | }; | |
34 | ||
ca8eca68 | 35 | static struct class *raw_class; |
0078bff5 | 36 | static struct raw_device_data *raw_devices; |
8ed965d6 | 37 | static DEFINE_MUTEX(raw_mutex); |
62322d25 | 38 | static const struct file_operations raw_ctl_fops; /* forward declaration */ |
1da177e4 | 39 | |
0078bff5 JK |
40 | static int max_raw_minors = MAX_RAW_MINORS; |
41 | ||
42 | module_param(max_raw_minors, int, 0); | |
43 | MODULE_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 | */ | |
55 | static 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 | 91 | out1: |
e525fd89 | 92 | blkdev_put(bdev, filp->f_mode | FMODE_EXCL); |
1da177e4 | 93 | out: |
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 | */ | |
102 | static 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 |
121 | static long |
122 | raw_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 | ||
128 | static 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 | 188 | static 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 |
209 | static 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 | |
244 | struct raw32_config_request { | |
245 | compat_int_t raw_minor; | |
246 | compat_u64 block_major; | |
247 | compat_u64 block_minor; | |
248 | }; | |
249 | ||
250 | static 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 | 286 | static 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 | 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 | ||
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 | 353 | error_region: |
0078bff5 | 354 | unregister_chrdev_region(dev, max_raw_minors); |
1da177e4 | 355 | error: |
0078bff5 | 356 | vfree(raw_devices); |
3e26a423 | 357 | return ret; |
1da177e4 LT |
358 | } |
359 | ||
360 | static 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 | ||
368 | module_init(raw_init); | |
369 | module_exit(raw_exit); | |
370 | MODULE_LICENSE("GPL"); |