xref: /linux/block/bsg.c (revision 9632e78e82648aa98340df78eab9106f63da151e) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * bsg.c - block layer implementation of the sg v4 interface
4  */
5 #include <linux/module.h>
6 #include <linux/init.h>
7 #include <linux/file.h>
8 #include <linux/blkdev.h>
9 #include <linux/cdev.h>
10 #include <linux/jiffies.h>
11 #include <linux/percpu.h>
12 #include <linux/idr.h>
13 #include <linux/bsg.h>
14 #include <linux/slab.h>
15 
16 #include <scsi/scsi.h>
17 #include <scsi/scsi_ioctl.h>
18 #include <scsi/scsi_cmnd.h>
19 #include <scsi/scsi_device.h>
20 #include <scsi/scsi_driver.h>
21 #include <scsi/sg.h>
22 
23 #define BSG_DESCRIPTION	"Block layer SCSI generic (bsg) driver"
24 #define BSG_VERSION	"0.4"
25 
26 #define bsg_dbg(bd, fmt, ...) \
27 	pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__)
28 
29 struct bsg_device {
30 	struct request_queue *queue;
31 	spinlock_t lock;
32 	struct hlist_node dev_list;
33 	refcount_t ref_count;
34 	char name[20];
35 	int max_queue;
36 };
37 
38 #define BSG_DEFAULT_CMDS	64
39 #define BSG_MAX_DEVS		32768
40 
41 static DEFINE_MUTEX(bsg_mutex);
42 static DEFINE_IDR(bsg_minor_idr);
43 
44 #define BSG_LIST_ARRAY_SIZE	8
45 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
46 
47 static struct class *bsg_class;
48 static int bsg_major;
49 
50 static inline struct hlist_head *bsg_dev_idx_hash(int index)
51 {
52 	return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
53 }
54 
55 #define uptr64(val) ((void __user *)(uintptr_t)(val))
56 
57 static int bsg_scsi_check_proto(struct sg_io_v4 *hdr)
58 {
59 	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
60 	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
61 		return -EINVAL;
62 	return 0;
63 }
64 
65 static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
66 		fmode_t mode)
67 {
68 	struct scsi_request *sreq = scsi_req(rq);
69 
70 	if (hdr->dout_xfer_len && hdr->din_xfer_len) {
71 		pr_warn_once("BIDI support in bsg has been removed.\n");
72 		return -EOPNOTSUPP;
73 	}
74 
75 	sreq->cmd_len = hdr->request_len;
76 	if (sreq->cmd_len > BLK_MAX_CDB) {
77 		sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
78 		if (!sreq->cmd)
79 			return -ENOMEM;
80 	}
81 
82 	if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
83 		return -EFAULT;
84 	if (blk_verify_command(sreq->cmd, mode))
85 		return -EPERM;
86 	return 0;
87 }
88 
89 static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
90 {
91 	struct scsi_request *sreq = scsi_req(rq);
92 	int ret = 0;
93 
94 	/*
95 	 * fill in all the output members
96 	 */
97 	hdr->device_status = sreq->result & 0xff;
98 	hdr->transport_status = host_byte(sreq->result);
99 	hdr->driver_status = 0;
100 	if (scsi_status_is_check_condition(sreq->result))
101 		hdr->driver_status = DRIVER_SENSE;
102 	hdr->info = 0;
103 	if (hdr->device_status || hdr->transport_status || hdr->driver_status)
104 		hdr->info |= SG_INFO_CHECK;
105 	hdr->response_len = 0;
106 
107 	if (sreq->sense_len && hdr->response) {
108 		int len = min_t(unsigned int, hdr->max_response_len,
109 					sreq->sense_len);
110 
111 		if (copy_to_user(uptr64(hdr->response), sreq->sense, len))
112 			ret = -EFAULT;
113 		else
114 			hdr->response_len = len;
115 	}
116 
117 	if (rq_data_dir(rq) == READ)
118 		hdr->din_resid = sreq->resid_len;
119 	else
120 		hdr->dout_resid = sreq->resid_len;
121 
122 	return ret;
123 }
124 
125 static void bsg_scsi_free_rq(struct request *rq)
126 {
127 	scsi_req_free_cmd(scsi_req(rq));
128 }
129 
130 static const struct bsg_ops bsg_scsi_ops = {
131 	.check_proto		= bsg_scsi_check_proto,
132 	.fill_hdr		= bsg_scsi_fill_hdr,
133 	.complete_rq		= bsg_scsi_complete_rq,
134 	.free_rq		= bsg_scsi_free_rq,
135 };
136 
137 static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
138 {
139 	struct request *rq;
140 	struct bio *bio;
141 	struct sg_io_v4 hdr;
142 	int ret;
143 
144 	if (copy_from_user(&hdr, uarg, sizeof(hdr)))
145 		return -EFAULT;
146 
147 	if (!q->bsg_dev.class_dev)
148 		return -ENXIO;
149 
150 	if (hdr.guard != 'Q')
151 		return -EINVAL;
152 	ret = q->bsg_dev.ops->check_proto(&hdr);
153 	if (ret)
154 		return ret;
155 
156 	rq = blk_get_request(q, hdr.dout_xfer_len ?
157 			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
158 	if (IS_ERR(rq))
159 		return PTR_ERR(rq);
160 
161 	ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode);
162 	if (ret) {
163 		blk_put_request(rq);
164 		return ret;
165 	}
166 
167 	rq->timeout = msecs_to_jiffies(hdr.timeout);
168 	if (!rq->timeout)
169 		rq->timeout = q->sg_timeout;
170 	if (!rq->timeout)
171 		rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
172 	if (rq->timeout < BLK_MIN_SG_TIMEOUT)
173 		rq->timeout = BLK_MIN_SG_TIMEOUT;
174 
175 	if (hdr.dout_xfer_len) {
176 		ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp),
177 				hdr.dout_xfer_len, GFP_KERNEL);
178 	} else if (hdr.din_xfer_len) {
179 		ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.din_xferp),
180 				hdr.din_xfer_len, GFP_KERNEL);
181 	}
182 
183 	if (ret)
184 		goto out_free_rq;
185 
186 	bio = rq->bio;
187 
188 	blk_execute_rq(NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL));
189 	ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr);
190 	blk_rq_unmap_user(bio);
191 
192 out_free_rq:
193 	rq->q->bsg_dev.ops->free_rq(rq);
194 	blk_put_request(rq);
195 	if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
196 		return -EFAULT;
197 	return ret;
198 }
199 
200 static struct bsg_device *bsg_alloc_device(void)
201 {
202 	struct bsg_device *bd;
203 
204 	bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
205 	if (unlikely(!bd))
206 		return NULL;
207 
208 	spin_lock_init(&bd->lock);
209 	bd->max_queue = BSG_DEFAULT_CMDS;
210 	INIT_HLIST_NODE(&bd->dev_list);
211 	return bd;
212 }
213 
214 static int bsg_put_device(struct bsg_device *bd)
215 {
216 	struct request_queue *q = bd->queue;
217 
218 	mutex_lock(&bsg_mutex);
219 
220 	if (!refcount_dec_and_test(&bd->ref_count)) {
221 		mutex_unlock(&bsg_mutex);
222 		return 0;
223 	}
224 
225 	hlist_del(&bd->dev_list);
226 	mutex_unlock(&bsg_mutex);
227 
228 	bsg_dbg(bd, "tearing down\n");
229 
230 	/*
231 	 * close can always block
232 	 */
233 	kfree(bd);
234 	blk_put_queue(q);
235 	return 0;
236 }
237 
238 static struct bsg_device *bsg_add_device(struct inode *inode,
239 					 struct request_queue *rq,
240 					 struct file *file)
241 {
242 	struct bsg_device *bd;
243 	unsigned char buf[32];
244 
245 	lockdep_assert_held(&bsg_mutex);
246 
247 	if (!blk_get_queue(rq))
248 		return ERR_PTR(-ENXIO);
249 
250 	bd = bsg_alloc_device();
251 	if (!bd) {
252 		blk_put_queue(rq);
253 		return ERR_PTR(-ENOMEM);
254 	}
255 
256 	bd->queue = rq;
257 
258 	refcount_set(&bd->ref_count, 1);
259 	hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
260 
261 	strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
262 	bsg_dbg(bd, "bound to <%s>, max queue %d\n",
263 		format_dev_t(buf, inode->i_rdev), bd->max_queue);
264 
265 	return bd;
266 }
267 
268 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
269 {
270 	struct bsg_device *bd;
271 
272 	lockdep_assert_held(&bsg_mutex);
273 
274 	hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
275 		if (bd->queue == q) {
276 			refcount_inc(&bd->ref_count);
277 			goto found;
278 		}
279 	}
280 	bd = NULL;
281 found:
282 	return bd;
283 }
284 
285 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
286 {
287 	struct bsg_device *bd;
288 	struct bsg_class_device *bcd;
289 
290 	/*
291 	 * find the class device
292 	 */
293 	mutex_lock(&bsg_mutex);
294 	bcd = idr_find(&bsg_minor_idr, iminor(inode));
295 
296 	if (!bcd) {
297 		bd = ERR_PTR(-ENODEV);
298 		goto out_unlock;
299 	}
300 
301 	bd = __bsg_get_device(iminor(inode), bcd->queue);
302 	if (!bd)
303 		bd = bsg_add_device(inode, bcd->queue, file);
304 
305 out_unlock:
306 	mutex_unlock(&bsg_mutex);
307 	return bd;
308 }
309 
310 static int bsg_open(struct inode *inode, struct file *file)
311 {
312 	struct bsg_device *bd;
313 
314 	bd = bsg_get_device(inode, file);
315 
316 	if (IS_ERR(bd))
317 		return PTR_ERR(bd);
318 
319 	file->private_data = bd;
320 	return 0;
321 }
322 
323 static int bsg_release(struct inode *inode, struct file *file)
324 {
325 	struct bsg_device *bd = file->private_data;
326 
327 	file->private_data = NULL;
328 	return bsg_put_device(bd);
329 }
330 
331 static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
332 {
333 	return put_user(bd->max_queue, uarg);
334 }
335 
336 static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
337 {
338 	int queue;
339 
340 	if (get_user(queue, uarg))
341 		return -EFAULT;
342 	if (queue < 1)
343 		return -EINVAL;
344 
345 	spin_lock_irq(&bd->lock);
346 	bd->max_queue = queue;
347 	spin_unlock_irq(&bd->lock);
348 	return 0;
349 }
350 
351 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
352 {
353 	struct bsg_device *bd = file->private_data;
354 	void __user *uarg = (void __user *) arg;
355 
356 	switch (cmd) {
357 	/*
358 	 * Our own ioctls
359 	 */
360 	case SG_GET_COMMAND_Q:
361 		return bsg_get_command_q(bd, uarg);
362 	case SG_SET_COMMAND_Q:
363 		return bsg_set_command_q(bd, uarg);
364 
365 	/*
366 	 * SCSI/sg ioctls
367 	 */
368 	case SG_GET_VERSION_NUM:
369 	case SCSI_IOCTL_GET_IDLUN:
370 	case SCSI_IOCTL_GET_BUS_NUMBER:
371 	case SG_SET_TIMEOUT:
372 	case SG_GET_TIMEOUT:
373 	case SG_GET_RESERVED_SIZE:
374 	case SG_SET_RESERVED_SIZE:
375 	case SG_EMULATED_HOST:
376 	case SCSI_IOCTL_SEND_COMMAND:
377 		return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
378 	case SG_IO:
379 		return bsg_sg_io(bd->queue, file->f_mode, uarg);
380 	default:
381 		return -ENOTTY;
382 	}
383 }
384 
385 static const struct file_operations bsg_fops = {
386 	.open		=	bsg_open,
387 	.release	=	bsg_release,
388 	.unlocked_ioctl	=	bsg_ioctl,
389 	.compat_ioctl	=	compat_ptr_ioctl,
390 	.owner		=	THIS_MODULE,
391 	.llseek		=	default_llseek,
392 };
393 
394 void bsg_unregister_queue(struct request_queue *q)
395 {
396 	struct bsg_class_device *bcd = &q->bsg_dev;
397 
398 	if (!bcd->class_dev)
399 		return;
400 
401 	mutex_lock(&bsg_mutex);
402 	idr_remove(&bsg_minor_idr, bcd->minor);
403 	if (q->kobj.sd)
404 		sysfs_remove_link(&q->kobj, "bsg");
405 	device_unregister(bcd->class_dev);
406 	bcd->class_dev = NULL;
407 	mutex_unlock(&bsg_mutex);
408 }
409 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
410 
411 int bsg_register_queue(struct request_queue *q, struct device *parent,
412 		const char *name, const struct bsg_ops *ops)
413 {
414 	struct bsg_class_device *bcd;
415 	dev_t dev;
416 	int ret;
417 	struct device *class_dev = NULL;
418 
419 	/*
420 	 * we need a proper transport to send commands, not a stacked device
421 	 */
422 	if (!queue_is_mq(q))
423 		return 0;
424 
425 	bcd = &q->bsg_dev;
426 	memset(bcd, 0, sizeof(*bcd));
427 
428 	mutex_lock(&bsg_mutex);
429 
430 	ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
431 	if (ret < 0) {
432 		if (ret == -ENOSPC) {
433 			printk(KERN_ERR "bsg: too many bsg devices\n");
434 			ret = -EINVAL;
435 		}
436 		goto unlock;
437 	}
438 
439 	bcd->minor = ret;
440 	bcd->queue = q;
441 	bcd->ops = ops;
442 	dev = MKDEV(bsg_major, bcd->minor);
443 	class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name);
444 	if (IS_ERR(class_dev)) {
445 		ret = PTR_ERR(class_dev);
446 		goto idr_remove;
447 	}
448 	bcd->class_dev = class_dev;
449 
450 	if (q->kobj.sd) {
451 		ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
452 		if (ret)
453 			goto unregister_class_dev;
454 	}
455 
456 	mutex_unlock(&bsg_mutex);
457 	return 0;
458 
459 unregister_class_dev:
460 	device_unregister(class_dev);
461 idr_remove:
462 	idr_remove(&bsg_minor_idr, bcd->minor);
463 unlock:
464 	mutex_unlock(&bsg_mutex);
465 	return ret;
466 }
467 
468 int bsg_scsi_register_queue(struct request_queue *q, struct device *parent)
469 {
470 	if (!blk_queue_scsi_passthrough(q)) {
471 		WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
472 		return -EINVAL;
473 	}
474 
475 	return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops);
476 }
477 EXPORT_SYMBOL_GPL(bsg_scsi_register_queue);
478 
479 static struct cdev bsg_cdev;
480 
481 static char *bsg_devnode(struct device *dev, umode_t *mode)
482 {
483 	return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
484 }
485 
486 static int __init bsg_init(void)
487 {
488 	int ret, i;
489 	dev_t devid;
490 
491 	for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
492 		INIT_HLIST_HEAD(&bsg_device_list[i]);
493 
494 	bsg_class = class_create(THIS_MODULE, "bsg");
495 	if (IS_ERR(bsg_class))
496 		return PTR_ERR(bsg_class);
497 	bsg_class->devnode = bsg_devnode;
498 
499 	ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
500 	if (ret)
501 		goto destroy_bsg_class;
502 
503 	bsg_major = MAJOR(devid);
504 
505 	cdev_init(&bsg_cdev, &bsg_fops);
506 	ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
507 	if (ret)
508 		goto unregister_chrdev;
509 
510 	printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
511 	       " loaded (major %d)\n", bsg_major);
512 	return 0;
513 unregister_chrdev:
514 	unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
515 destroy_bsg_class:
516 	class_destroy(bsg_class);
517 	return ret;
518 }
519 
520 MODULE_AUTHOR("Jens Axboe");
521 MODULE_DESCRIPTION(BSG_DESCRIPTION);
522 MODULE_LICENSE("GPL");
523 
524 device_initcall(bsg_init);
525