]>
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> |
c0bed680 | 22 | #include <linux/smp_lock.h> |
5a0e3ad6 | 23 | #include <linux/gfp.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 | ||
c0bed680 | 58 | lock_kernel(); |
8ed965d6 | 59 | mutex_lock(&raw_mutex); |
1da177e4 LT |
60 | |
61 | /* | |
62 | * All we need to do on open is check that the device is bound. | |
63 | */ | |
64 | bdev = raw_devices[minor].binding; | |
65 | err = -ENODEV; | |
66 | if (!bdev) | |
67 | goto out; | |
68 | igrab(bdev->bd_inode); | |
572c4892 | 69 | err = blkdev_get(bdev, filp->f_mode); |
1da177e4 LT |
70 | if (err) |
71 | goto out; | |
72 | err = bd_claim(bdev, raw_open); | |
73 | if (err) | |
74 | goto out1; | |
e1defc4f | 75 | err = set_blocksize(bdev, bdev_logical_block_size(bdev)); |
1da177e4 LT |
76 | if (err) |
77 | goto out2; | |
78 | filp->f_flags |= O_DIRECT; | |
79 | filp->f_mapping = bdev->bd_inode->i_mapping; | |
80 | if (++raw_devices[minor].inuse == 1) | |
a7113a96 | 81 | filp->f_path.dentry->d_inode->i_mapping = |
1da177e4 LT |
82 | bdev->bd_inode->i_mapping; |
83 | filp->private_data = bdev; | |
8ed965d6 | 84 | mutex_unlock(&raw_mutex); |
c0bed680 | 85 | unlock_kernel(); |
1da177e4 LT |
86 | return 0; |
87 | ||
88 | out2: | |
89 | bd_release(bdev); | |
90 | out1: | |
9a1c3542 | 91 | blkdev_put(bdev, filp->f_mode); |
1da177e4 | 92 | out: |
8ed965d6 | 93 | mutex_unlock(&raw_mutex); |
996ff68d | 94 | unlock_kernel(); |
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 LT |
108 | bdev = raw_devices[minor].binding; |
109 | if (--raw_devices[minor].inuse == 0) { | |
110 | /* Here inode->i_mapping == bdev->bd_inode->i_mapping */ | |
111 | inode->i_mapping = &inode->i_data; | |
112 | inode->i_mapping->backing_dev_info = &default_backing_dev_info; | |
113 | } | |
8ed965d6 | 114 | mutex_unlock(&raw_mutex); |
1da177e4 LT |
115 | |
116 | bd_release(bdev); | |
9a1c3542 | 117 | blkdev_put(bdev, filp->f_mode); |
1da177e4 LT |
118 | return 0; |
119 | } | |
120 | ||
121 | /* | |
122 | * Forward ioctls to the underlying block device. | |
123 | */ | |
55929332 AB |
124 | static long |
125 | raw_ioctl(struct file *filp, unsigned int command, unsigned long arg) | |
1da177e4 LT |
126 | { |
127 | struct block_device *bdev = filp->private_data; | |
55929332 | 128 | int ret; |
1da177e4 | 129 | |
55929332 AB |
130 | lock_kernel(); |
131 | ret = blkdev_ioctl(bdev, 0, command, arg); | |
132 | unlock_kernel(); | |
133 | ||
134 | return ret; | |
1da177e4 LT |
135 | } |
136 | ||
137 | static void bind_device(struct raw_config_request *rq) | |
138 | { | |
38ca6c34 | 139 | device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor)); |
03457cd4 GKH |
140 | device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor), NULL, |
141 | "raw%d", rq->raw_minor); | |
1da177e4 LT |
142 | } |
143 | ||
144 | /* | |
145 | * Deal with ioctls against the raw-device control interface, to bind | |
146 | * and unbind other raw devices. | |
147 | */ | |
55929332 AB |
148 | static long raw_ctl_ioctl(struct file *filp, unsigned int command, |
149 | unsigned long arg) | |
1da177e4 LT |
150 | { |
151 | struct raw_config_request rq; | |
152 | struct raw_device_data *rawdev; | |
153 | int err = 0; | |
154 | ||
55929332 | 155 | lock_kernel(); |
1da177e4 LT |
156 | switch (command) { |
157 | case RAW_SETBIND: | |
158 | case RAW_GETBIND: | |
159 | ||
160 | /* First, find out which raw minor we want */ | |
161 | ||
162 | if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) { | |
163 | err = -EFAULT; | |
164 | goto out; | |
165 | } | |
166 | ||
38584c14 | 167 | if (rq.raw_minor <= 0 || rq.raw_minor >= MAX_RAW_MINORS) { |
1da177e4 LT |
168 | err = -EINVAL; |
169 | goto out; | |
170 | } | |
171 | rawdev = &raw_devices[rq.raw_minor]; | |
172 | ||
173 | if (command == RAW_SETBIND) { | |
174 | dev_t dev; | |
175 | ||
176 | /* | |
177 | * This is like making block devices, so demand the | |
178 | * same capability | |
179 | */ | |
180 | if (!capable(CAP_SYS_ADMIN)) { | |
181 | err = -EPERM; | |
182 | goto out; | |
183 | } | |
184 | ||
185 | /* | |
186 | * For now, we don't need to check that the underlying | |
187 | * block device is present or not: we can do that when | |
188 | * the raw device is opened. Just check that the | |
189 | * major/minor numbers make sense. | |
190 | */ | |
191 | ||
192 | dev = MKDEV(rq.block_major, rq.block_minor); | |
193 | if ((rq.block_major == 0 && rq.block_minor != 0) || | |
194 | MAJOR(dev) != rq.block_major || | |
195 | MINOR(dev) != rq.block_minor) { | |
196 | err = -EINVAL; | |
197 | goto out; | |
198 | } | |
199 | ||
8ed965d6 | 200 | mutex_lock(&raw_mutex); |
1da177e4 | 201 | if (rawdev->inuse) { |
8ed965d6 | 202 | mutex_unlock(&raw_mutex); |
1da177e4 LT |
203 | err = -EBUSY; |
204 | goto out; | |
205 | } | |
206 | if (rawdev->binding) { | |
207 | bdput(rawdev->binding); | |
208 | module_put(THIS_MODULE); | |
209 | } | |
210 | if (rq.block_major == 0 && rq.block_minor == 0) { | |
211 | /* unbind */ | |
212 | rawdev->binding = NULL; | |
38ca6c34 | 213 | device_destroy(raw_class, |
ca8eca68 | 214 | MKDEV(RAW_MAJOR, rq.raw_minor)); |
1da177e4 LT |
215 | } else { |
216 | rawdev->binding = bdget(dev); | |
217 | if (rawdev->binding == NULL) | |
218 | err = -ENOMEM; | |
219 | else { | |
220 | __module_get(THIS_MODULE); | |
221 | bind_device(&rq); | |
222 | } | |
223 | } | |
8ed965d6 | 224 | mutex_unlock(&raw_mutex); |
1da177e4 LT |
225 | } else { |
226 | struct block_device *bdev; | |
227 | ||
8ed965d6 | 228 | mutex_lock(&raw_mutex); |
1da177e4 LT |
229 | bdev = rawdev->binding; |
230 | if (bdev) { | |
231 | rq.block_major = MAJOR(bdev->bd_dev); | |
232 | rq.block_minor = MINOR(bdev->bd_dev); | |
233 | } else { | |
234 | rq.block_major = rq.block_minor = 0; | |
235 | } | |
8ed965d6 | 236 | mutex_unlock(&raw_mutex); |
1da177e4 LT |
237 | if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) { |
238 | err = -EFAULT; | |
239 | goto out; | |
240 | } | |
241 | } | |
242 | break; | |
243 | default: | |
244 | err = -EINVAL; | |
245 | break; | |
246 | } | |
247 | out: | |
55929332 | 248 | unlock_kernel(); |
1da177e4 LT |
249 | return err; |
250 | } | |
251 | ||
62322d25 | 252 | static const struct file_operations raw_fops = { |
55929332 AB |
253 | .read = do_sync_read, |
254 | .aio_read = generic_file_aio_read, | |
255 | .write = do_sync_write, | |
256 | .aio_write = blkdev_aio_write, | |
257 | .fsync = blkdev_fsync, | |
258 | .open = raw_open, | |
259 | .release = raw_release, | |
260 | .unlocked_ioctl = raw_ioctl, | |
261 | .owner = THIS_MODULE, | |
1da177e4 LT |
262 | }; |
263 | ||
62322d25 | 264 | static const struct file_operations raw_ctl_fops = { |
55929332 AB |
265 | .unlocked_ioctl = raw_ctl_ioctl, |
266 | .open = raw_open, | |
267 | .owner = THIS_MODULE, | |
1da177e4 LT |
268 | }; |
269 | ||
7e7654a9 | 270 | static struct cdev raw_cdev; |
1da177e4 | 271 | |
e454cea2 | 272 | static char *raw_devnode(struct device *dev, mode_t *mode) |
6fd46933 KS |
273 | { |
274 | return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev)); | |
275 | } | |
276 | ||
1da177e4 LT |
277 | static int __init raw_init(void) |
278 | { | |
1da177e4 | 279 | dev_t dev = MKDEV(RAW_MAJOR, 0); |
3e26a423 | 280 | int ret; |
1da177e4 | 281 | |
3e26a423 REB |
282 | ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw"); |
283 | if (ret) | |
1da177e4 LT |
284 | goto error; |
285 | ||
286 | cdev_init(&raw_cdev, &raw_fops); | |
3e26a423 REB |
287 | ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS); |
288 | if (ret) { | |
1da177e4 | 289 | kobject_put(&raw_cdev.kobj); |
3e26a423 | 290 | goto error_region; |
1da177e4 LT |
291 | } |
292 | ||
ca8eca68 | 293 | raw_class = class_create(THIS_MODULE, "raw"); |
1da177e4 LT |
294 | if (IS_ERR(raw_class)) { |
295 | printk(KERN_ERR "Error creating raw class.\n"); | |
296 | cdev_del(&raw_cdev); | |
3e26a423 REB |
297 | ret = PTR_ERR(raw_class); |
298 | goto error_region; | |
1da177e4 | 299 | } |
e454cea2 | 300 | raw_class->devnode = raw_devnode; |
03457cd4 | 301 | device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl"); |
1da177e4 | 302 | |
1da177e4 LT |
303 | return 0; |
304 | ||
3e26a423 REB |
305 | error_region: |
306 | unregister_chrdev_region(dev, MAX_RAW_MINORS); | |
1da177e4 | 307 | error: |
3e26a423 | 308 | return ret; |
1da177e4 LT |
309 | } |
310 | ||
311 | static void __exit raw_exit(void) | |
312 | { | |
38ca6c34 | 313 | device_destroy(raw_class, MKDEV(RAW_MAJOR, 0)); |
ca8eca68 | 314 | class_destroy(raw_class); |
1da177e4 LT |
315 | cdev_del(&raw_cdev); |
316 | unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS); | |
317 | } | |
318 | ||
319 | module_init(raw_init); | |
320 | module_exit(raw_exit); | |
321 | MODULE_LICENSE("GPL"); |