xref: /linux/block/bsg.c (revision 8f8d5745bb520c76b81abef4a2cb3023d0313bfd) 
1 /*
2  * bsg.c - block layer implementation of the sg v4 interface
3  *
4  * Copyright (C) 2004 Jens Axboe <axboe@suse.de> SUSE Labs
5  * Copyright (C) 2004 Peter M. Jones <pjones@redhat.com>
6  *
7  *  This file is subject to the terms and conditions of the GNU General Public
8  *  License version 2.  See the file "COPYING" in the main directory of this
9  *  archive for more details.
10  *
11  */
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/file.h>
15 #include <linux/blkdev.h>
16 #include <linux/cdev.h>
17 #include <linux/jiffies.h>
18 #include <linux/percpu.h>
19 #include <linux/idr.h>
20 #include <linux/bsg.h>
21 #include <linux/slab.h>
22 
23 #include <scsi/scsi.h>
24 #include <scsi/scsi_ioctl.h>
25 #include <scsi/scsi_cmnd.h>
26 #include <scsi/scsi_device.h>
27 #include <scsi/scsi_driver.h>
28 #include <scsi/sg.h>
29 
30 #define BSG_DESCRIPTION	"Block layer SCSI generic (bsg) driver"
31 #define BSG_VERSION	"0.4"
32 
33 #define bsg_dbg(bd, fmt, ...) \
34 	pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__)
35 
36 struct bsg_device {
37 	struct request_queue *queue;
38 	spinlock_t lock;
39 	struct hlist_node dev_list;
40 	refcount_t ref_count;
41 	char name[20];
42 	int max_queue;
43 };
44 
45 #define BSG_DEFAULT_CMDS	64
46 #define BSG_MAX_DEVS		32768
47 
48 static DEFINE_MUTEX(bsg_mutex);
49 static DEFINE_IDR(bsg_minor_idr);
50 
51 #define BSG_LIST_ARRAY_SIZE	8
52 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
53 
54 static struct class *bsg_class;
55 static int bsg_major;
56 
57 static inline struct hlist_head *bsg_dev_idx_hash(int index)
58 {
59 	return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
60 }
61 
62 #define uptr64(val) ((void __user *)(uintptr_t)(val))
63 
64 static int bsg_scsi_check_proto(struct sg_io_v4 *hdr)
65 {
66 	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
67 	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
68 		return -EINVAL;
69 	return 0;
70 }
71 
72 static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
73 		fmode_t mode)
74 {
75 	struct scsi_request *sreq = scsi_req(rq);
76 
77 	if (hdr->dout_xfer_len && hdr->din_xfer_len) {
78 		pr_warn_once("BIDI support in bsg has been removed.\n");
79 		return -EOPNOTSUPP;
80 	}
81 
82 	sreq->cmd_len = hdr->request_len;
83 	if (sreq->cmd_len > BLK_MAX_CDB) {
84 		sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
85 		if (!sreq->cmd)
86 			return -ENOMEM;
87 	}
88 
89 	if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
90 		return -EFAULT;
91 	if (blk_verify_command(sreq->cmd, mode))
92 		return -EPERM;
93 	return 0;
94 }
95 
96 static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
97 {
98 	struct scsi_request *sreq = scsi_req(rq);
99 	int ret = 0;
100 
101 	/*
102 	 * fill in all the output members
103 	 */
104 	hdr->device_status = sreq->result & 0xff;
105 	hdr->transport_status = host_byte(sreq->result);
106 	hdr->driver_status = driver_byte(sreq->result);
107 	hdr->info = 0;
108 	if (hdr->device_status || hdr->transport_status || hdr->driver_status)
109 		hdr->info |= SG_INFO_CHECK;
110 	hdr->response_len = 0;
111 
112 	if (sreq->sense_len && hdr->response) {
113 		int len = min_t(unsigned int, hdr->max_response_len,
114 					sreq->sense_len);
115 
116 		if (copy_to_user(uptr64(hdr->response), sreq->sense, len))
117 			ret = -EFAULT;
118 		else
119 			hdr->response_len = len;
120 	}
121 
122 	if (rq_data_dir(rq) == READ)
123 		hdr->din_resid = sreq->resid_len;
124 	else
125 		hdr->dout_resid = sreq->resid_len;
126 
127 	return ret;
128 }
129 
130 static void bsg_scsi_free_rq(struct request *rq)
131 {
132 	scsi_req_free_cmd(scsi_req(rq));
133 }
134 
135 static const struct bsg_ops bsg_scsi_ops = {
136 	.check_proto		= bsg_scsi_check_proto,
137 	.fill_hdr		= bsg_scsi_fill_hdr,
138 	.complete_rq		= bsg_scsi_complete_rq,
139 	.free_rq		= bsg_scsi_free_rq,
140 };
141 
142 static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
143 {
144 	struct request *rq;
145 	struct bio *bio;
146 	struct sg_io_v4 hdr;
147 	int ret;
148 
149 	if (copy_from_user(&hdr, uarg, sizeof(hdr)))
150 		return -EFAULT;
151 
152 	if (!q->bsg_dev.class_dev)
153 		return -ENXIO;
154 
155 	if (hdr.guard != 'Q')
156 		return -EINVAL;
157 	ret = q->bsg_dev.ops->check_proto(&hdr);
158 	if (ret)
159 		return ret;
160 
161 	rq = blk_get_request(q, hdr.dout_xfer_len ?
162 			REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);
163 	if (IS_ERR(rq))
164 		return PTR_ERR(rq);
165 
166 	ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode);
167 	if (ret)
168 		return ret;
169 
170 	rq->timeout = msecs_to_jiffies(hdr.timeout);
171 	if (!rq->timeout)
172 		rq->timeout = q->sg_timeout;
173 	if (!rq->timeout)
174 		rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
175 	if (rq->timeout < BLK_MIN_SG_TIMEOUT)
176 		rq->timeout = BLK_MIN_SG_TIMEOUT;
177 
178 	if (hdr.dout_xfer_len) {
179 		ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp),
180 				hdr.dout_xfer_len, GFP_KERNEL);
181 	} else if (hdr.din_xfer_len) {
182 		ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.din_xferp),
183 				hdr.din_xfer_len, GFP_KERNEL);
184 	}
185 
186 	if (ret)
187 		goto out_free_rq;
188 
189 	bio = rq->bio;
190 
191 	blk_execute_rq(q, NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL));
192 	ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr);
193 	blk_rq_unmap_user(bio);
194 
195 out_free_rq:
196 	rq->q->bsg_dev.ops->free_rq(rq);
197 	blk_put_request(rq);
198 	if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
199 		return -EFAULT;
200 	return ret;
201 }
202 
203 static struct bsg_device *bsg_alloc_device(void)
204 {
205 	struct bsg_device *bd;
206 
207 	bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
208 	if (unlikely(!bd))
209 		return NULL;
210 
211 	spin_lock_init(&bd->lock);
212 	bd->max_queue = BSG_DEFAULT_CMDS;
213 	INIT_HLIST_NODE(&bd->dev_list);
214 	return bd;
215 }
216 
217 static int bsg_put_device(struct bsg_device *bd)
218 {
219 	struct request_queue *q = bd->queue;
220 
221 	mutex_lock(&bsg_mutex);
222 
223 	if (!refcount_dec_and_test(&bd->ref_count)) {
224 		mutex_unlock(&bsg_mutex);
225 		return 0;
226 	}
227 
228 	hlist_del(&bd->dev_list);
229 	mutex_unlock(&bsg_mutex);
230 
231 	bsg_dbg(bd, "tearing down\n");
232 
233 	/*
234 	 * close can always block
235 	 */
236 	kfree(bd);
237 	blk_put_queue(q);
238 	return 0;
239 }
240 
241 static struct bsg_device *bsg_add_device(struct inode *inode,
242 					 struct request_queue *rq,
243 					 struct file *file)
244 {
245 	struct bsg_device *bd;
246 	unsigned char buf[32];
247 
248 	lockdep_assert_held(&bsg_mutex);
249 
250 	if (!blk_get_queue(rq))
251 		return ERR_PTR(-ENXIO);
252 
253 	bd = bsg_alloc_device();
254 	if (!bd) {
255 		blk_put_queue(rq);
256 		return ERR_PTR(-ENOMEM);
257 	}
258 
259 	bd->queue = rq;
260 
261 	refcount_set(&bd->ref_count, 1);
262 	hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
263 
264 	strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
265 	bsg_dbg(bd, "bound to <%s>, max queue %d\n",
266 		format_dev_t(buf, inode->i_rdev), bd->max_queue);
267 
268 	return bd;
269 }
270 
271 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
272 {
273 	struct bsg_device *bd;
274 
275 	lockdep_assert_held(&bsg_mutex);
276 
277 	hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
278 		if (bd->queue == q) {
279 			refcount_inc(&bd->ref_count);
280 			goto found;
281 		}
282 	}
283 	bd = NULL;
284 found:
285 	return bd;
286 }
287 
288 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
289 {
290 	struct bsg_device *bd;
291 	struct bsg_class_device *bcd;
292 
293 	/*
294 	 * find the class device
295 	 */
296 	mutex_lock(&bsg_mutex);
297 	bcd = idr_find(&bsg_minor_idr, iminor(inode));
298 
299 	if (!bcd) {
300 		bd = ERR_PTR(-ENODEV);
301 		goto out_unlock;
302 	}
303 
304 	bd = __bsg_get_device(iminor(inode), bcd->queue);
305 	if (!bd)
306 		bd = bsg_add_device(inode, bcd->queue, file);
307 
308 out_unlock:
309 	mutex_unlock(&bsg_mutex);
310 	return bd;
311 }
312 
313 static int bsg_open(struct inode *inode, struct file *file)
314 {
315 	struct bsg_device *bd;
316 
317 	bd = bsg_get_device(inode, file);
318 
319 	if (IS_ERR(bd))
320 		return PTR_ERR(bd);
321 
322 	file->private_data = bd;
323 	return 0;
324 }
325 
326 static int bsg_release(struct inode *inode, struct file *file)
327 {
328 	struct bsg_device *bd = file->private_data;
329 
330 	file->private_data = NULL;
331 	return bsg_put_device(bd);
332 }
333 
334 static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
335 {
336 	return put_user(bd->max_queue, uarg);
337 }
338 
339 static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
340 {
341 	int queue;
342 
343 	if (get_user(queue, uarg))
344 		return -EFAULT;
345 	if (queue < 1)
346 		return -EINVAL;
347 
348 	spin_lock_irq(&bd->lock);
349 	bd->max_queue = queue;
350 	spin_unlock_irq(&bd->lock);
351 	return 0;
352 }
353 
354 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
355 {
356 	struct bsg_device *bd = file->private_data;
357 	void __user *uarg = (void __user *) arg;
358 
359 	switch (cmd) {
360 	/*
361 	 * Our own ioctls
362 	 */
363 	case SG_GET_COMMAND_Q:
364 		return bsg_get_command_q(bd, uarg);
365 	case SG_SET_COMMAND_Q:
366 		return bsg_set_command_q(bd, uarg);
367 
368 	/*
369 	 * SCSI/sg ioctls
370 	 */
371 	case SG_GET_VERSION_NUM:
372 	case SCSI_IOCTL_GET_IDLUN:
373 	case SCSI_IOCTL_GET_BUS_NUMBER:
374 	case SG_SET_TIMEOUT:
375 	case SG_GET_TIMEOUT:
376 	case SG_GET_RESERVED_SIZE:
377 	case SG_SET_RESERVED_SIZE:
378 	case SG_EMULATED_HOST:
379 	case SCSI_IOCTL_SEND_COMMAND:
380 		return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
381 	case SG_IO:
382 		return bsg_sg_io(bd->queue, file->f_mode, uarg);
383 	default:
384 		return -ENOTTY;
385 	}
386 }
387 
388 static const struct file_operations bsg_fops = {
389 	.open		=	bsg_open,
390 	.release	=	bsg_release,
391 	.unlocked_ioctl	=	bsg_ioctl,
392 	.owner		=	THIS_MODULE,
393 	.llseek		=	default_llseek,
394 };
395 
396 void bsg_unregister_queue(struct request_queue *q)
397 {
398 	struct bsg_class_device *bcd = &q->bsg_dev;
399 
400 	if (!bcd->class_dev)
401 		return;
402 
403 	mutex_lock(&bsg_mutex);
404 	idr_remove(&bsg_minor_idr, bcd->minor);
405 	if (q->kobj.sd)
406 		sysfs_remove_link(&q->kobj, "bsg");
407 	device_unregister(bcd->class_dev);
408 	bcd->class_dev = NULL;
409 	mutex_unlock(&bsg_mutex);
410 }
411 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
412 
413 int bsg_register_queue(struct request_queue *q, struct device *parent,
414 		const char *name, const struct bsg_ops *ops)
415 {
416 	struct bsg_class_device *bcd;
417 	dev_t dev;
418 	int ret;
419 	struct device *class_dev = NULL;
420 
421 	/*
422 	 * we need a proper transport to send commands, not a stacked device
423 	 */
424 	if (!queue_is_mq(q))
425 		return 0;
426 
427 	bcd = &q->bsg_dev;
428 	memset(bcd, 0, sizeof(*bcd));
429 
430 	mutex_lock(&bsg_mutex);
431 
432 	ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
433 	if (ret < 0) {
434 		if (ret == -ENOSPC) {
435 			printk(KERN_ERR "bsg: too many bsg devices\n");
436 			ret = -EINVAL;
437 		}
438 		goto unlock;
439 	}
440 
441 	bcd->minor = ret;
442 	bcd->queue = q;
443 	bcd->ops = ops;
444 	dev = MKDEV(bsg_major, bcd->minor);
445 	class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name);
446 	if (IS_ERR(class_dev)) {
447 		ret = PTR_ERR(class_dev);
448 		goto idr_remove;
449 	}
450 	bcd->class_dev = class_dev;
451 
452 	if (q->kobj.sd) {
453 		ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
454 		if (ret)
455 			goto unregister_class_dev;
456 	}
457 
458 	mutex_unlock(&bsg_mutex);
459 	return 0;
460 
461 unregister_class_dev:
462 	device_unregister(class_dev);
463 idr_remove:
464 	idr_remove(&bsg_minor_idr, bcd->minor);
465 unlock:
466 	mutex_unlock(&bsg_mutex);
467 	return ret;
468 }
469 
470 int bsg_scsi_register_queue(struct request_queue *q, struct device *parent)
471 {
472 	if (!blk_queue_scsi_passthrough(q)) {
473 		WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
474 		return -EINVAL;
475 	}
476 
477 	return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops);
478 }
479 EXPORT_SYMBOL_GPL(bsg_scsi_register_queue);
480 
481 static struct cdev bsg_cdev;
482 
483 static char *bsg_devnode(struct device *dev, umode_t *mode)
484 {
485 	return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
486 }
487 
488 static int __init bsg_init(void)
489 {
490 	int ret, i;
491 	dev_t devid;
492 
493 	for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
494 		INIT_HLIST_HEAD(&bsg_device_list[i]);
495 
496 	bsg_class = class_create(THIS_MODULE, "bsg");
497 	if (IS_ERR(bsg_class))
498 		return PTR_ERR(bsg_class);
499 	bsg_class->devnode = bsg_devnode;
500 
501 	ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
502 	if (ret)
503 		goto destroy_bsg_class;
504 
505 	bsg_major = MAJOR(devid);
506 
507 	cdev_init(&bsg_cdev, &bsg_fops);
508 	ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
509 	if (ret)
510 		goto unregister_chrdev;
511 
512 	printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
513 	       " loaded (major %d)\n", bsg_major);
514 	return 0;
515 unregister_chrdev:
516 	unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
517 destroy_bsg_class:
518 	class_destroy(bsg_class);
519 	return ret;
520 }
521 
522 MODULE_AUTHOR("Jens Axboe");
523 MODULE_DESCRIPTION(BSG_DESCRIPTION);
524 MODULE_LICENSE("GPL");
525 
526 device_initcall(bsg_init);
527