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
bsg_dev_idx_hash(int index)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
bsg_scsi_check_proto(struct sg_io_v4 * hdr)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
bsg_scsi_fill_hdr(struct request * rq,struct sg_io_v4 * hdr,fmode_t mode)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
bsg_scsi_complete_rq(struct request * rq,struct sg_io_v4 * hdr)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 = driver_byte(sreq->result);
100 hdr->info = 0;
101 if (hdr->device_status || hdr->transport_status || hdr->driver_status)
102 hdr->info |= SG_INFO_CHECK;
103 hdr->response_len = 0;
104
105 if (sreq->sense_len && hdr->response) {
106 int len = min_t(unsigned int, hdr->max_response_len,
107 sreq->sense_len);
108
109 if (copy_to_user(uptr64(hdr->response), sreq->sense, len))
110 ret = -EFAULT;
111 else
112 hdr->response_len = len;
113 }
114
115 if (rq_data_dir(rq) == READ)
116 hdr->din_resid = sreq->resid_len;
117 else
118 hdr->dout_resid = sreq->resid_len;
119
120 return ret;
121 }
122
bsg_scsi_free_rq(struct request * rq)123 static void bsg_scsi_free_rq(struct request *rq)
124 {
125 scsi_req_free_cmd(scsi_req(rq));
126 }
127
128 static const struct bsg_ops bsg_scsi_ops = {
129 .check_proto = bsg_scsi_check_proto,
130 .fill_hdr = bsg_scsi_fill_hdr,
131 .complete_rq = bsg_scsi_complete_rq,
132 .free_rq = bsg_scsi_free_rq,
133 };
134
bsg_sg_io(struct request_queue * q,fmode_t mode,void __user * uarg)135 static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
136 {
137 struct request *rq;
138 struct bio *bio;
139 struct sg_io_v4 hdr;
140 int ret;
141
142 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
143 return -EFAULT;
144
145 if (!q->bsg_dev.class_dev)
146 return -ENXIO;
147
148 if (hdr.guard != 'Q')
149 return -EINVAL;
150 ret = q->bsg_dev.ops->check_proto(&hdr);
151 if (ret)
152 return ret;
153
154 rq = blk_get_request(q, hdr.dout_xfer_len ?
155 REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);
156 if (IS_ERR(rq))
157 return PTR_ERR(rq);
158
159 ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode);
160 if (ret)
161 return ret;
162
163 rq->timeout = msecs_to_jiffies(hdr.timeout);
164 if (!rq->timeout)
165 rq->timeout = q->sg_timeout;
166 if (!rq->timeout)
167 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
168 if (rq->timeout < BLK_MIN_SG_TIMEOUT)
169 rq->timeout = BLK_MIN_SG_TIMEOUT;
170
171 if (hdr.dout_xfer_len) {
172 ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp),
173 hdr.dout_xfer_len, GFP_KERNEL);
174 } else if (hdr.din_xfer_len) {
175 ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.din_xferp),
176 hdr.din_xfer_len, GFP_KERNEL);
177 }
178
179 if (ret)
180 goto out_free_rq;
181
182 bio = rq->bio;
183
184 blk_execute_rq(q, NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL));
185 ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr);
186 blk_rq_unmap_user(bio);
187
188 out_free_rq:
189 rq->q->bsg_dev.ops->free_rq(rq);
190 blk_put_request(rq);
191 if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
192 return -EFAULT;
193 return ret;
194 }
195
bsg_alloc_device(void)196 static struct bsg_device *bsg_alloc_device(void)
197 {
198 struct bsg_device *bd;
199
200 bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
201 if (unlikely(!bd))
202 return NULL;
203
204 spin_lock_init(&bd->lock);
205 bd->max_queue = BSG_DEFAULT_CMDS;
206 INIT_HLIST_NODE(&bd->dev_list);
207 return bd;
208 }
209
bsg_put_device(struct bsg_device * bd)210 static int bsg_put_device(struct bsg_device *bd)
211 {
212 struct request_queue *q = bd->queue;
213
214 mutex_lock(&bsg_mutex);
215
216 if (!refcount_dec_and_test(&bd->ref_count)) {
217 mutex_unlock(&bsg_mutex);
218 return 0;
219 }
220
221 hlist_del(&bd->dev_list);
222 mutex_unlock(&bsg_mutex);
223
224 bsg_dbg(bd, "tearing down\n");
225
226 /*
227 * close can always block
228 */
229 kfree(bd);
230 blk_put_queue(q);
231 return 0;
232 }
233
bsg_add_device(struct inode * inode,struct request_queue * rq,struct file * file)234 static struct bsg_device *bsg_add_device(struct inode *inode,
235 struct request_queue *rq,
236 struct file *file)
237 {
238 struct bsg_device *bd;
239 unsigned char buf[32];
240
241 lockdep_assert_held(&bsg_mutex);
242
243 if (!blk_get_queue(rq))
244 return ERR_PTR(-ENXIO);
245
246 bd = bsg_alloc_device();
247 if (!bd) {
248 blk_put_queue(rq);
249 return ERR_PTR(-ENOMEM);
250 }
251
252 bd->queue = rq;
253
254 refcount_set(&bd->ref_count, 1);
255 hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
256
257 strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
258 bsg_dbg(bd, "bound to <%s>, max queue %d\n",
259 format_dev_t(buf, inode->i_rdev), bd->max_queue);
260
261 return bd;
262 }
263
__bsg_get_device(int minor,struct request_queue * q)264 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
265 {
266 struct bsg_device *bd;
267
268 lockdep_assert_held(&bsg_mutex);
269
270 hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
271 if (bd->queue == q) {
272 refcount_inc(&bd->ref_count);
273 goto found;
274 }
275 }
276 bd = NULL;
277 found:
278 return bd;
279 }
280
bsg_get_device(struct inode * inode,struct file * file)281 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
282 {
283 struct bsg_device *bd;
284 struct bsg_class_device *bcd;
285
286 /*
287 * find the class device
288 */
289 mutex_lock(&bsg_mutex);
290 bcd = idr_find(&bsg_minor_idr, iminor(inode));
291
292 if (!bcd) {
293 bd = ERR_PTR(-ENODEV);
294 goto out_unlock;
295 }
296
297 bd = __bsg_get_device(iminor(inode), bcd->queue);
298 if (!bd)
299 bd = bsg_add_device(inode, bcd->queue, file);
300
301 out_unlock:
302 mutex_unlock(&bsg_mutex);
303 return bd;
304 }
305
bsg_open(struct inode * inode,struct file * file)306 static int bsg_open(struct inode *inode, struct file *file)
307 {
308 struct bsg_device *bd;
309
310 bd = bsg_get_device(inode, file);
311
312 if (IS_ERR(bd))
313 return PTR_ERR(bd);
314
315 file->private_data = bd;
316 return 0;
317 }
318
bsg_release(struct inode * inode,struct file * file)319 static int bsg_release(struct inode *inode, struct file *file)
320 {
321 struct bsg_device *bd = file->private_data;
322
323 file->private_data = NULL;
324 return bsg_put_device(bd);
325 }
326
bsg_get_command_q(struct bsg_device * bd,int __user * uarg)327 static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
328 {
329 return put_user(bd->max_queue, uarg);
330 }
331
bsg_set_command_q(struct bsg_device * bd,int __user * uarg)332 static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
333 {
334 int queue;
335
336 if (get_user(queue, uarg))
337 return -EFAULT;
338 if (queue < 1)
339 return -EINVAL;
340
341 spin_lock_irq(&bd->lock);
342 bd->max_queue = queue;
343 spin_unlock_irq(&bd->lock);
344 return 0;
345 }
346
bsg_ioctl(struct file * file,unsigned int cmd,unsigned long arg)347 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
348 {
349 struct bsg_device *bd = file->private_data;
350 void __user *uarg = (void __user *) arg;
351
352 switch (cmd) {
353 /*
354 * Our own ioctls
355 */
356 case SG_GET_COMMAND_Q:
357 return bsg_get_command_q(bd, uarg);
358 case SG_SET_COMMAND_Q:
359 return bsg_set_command_q(bd, uarg);
360
361 /*
362 * SCSI/sg ioctls
363 */
364 case SG_GET_VERSION_NUM:
365 case SCSI_IOCTL_GET_IDLUN:
366 case SCSI_IOCTL_GET_BUS_NUMBER:
367 case SG_SET_TIMEOUT:
368 case SG_GET_TIMEOUT:
369 case SG_GET_RESERVED_SIZE:
370 case SG_SET_RESERVED_SIZE:
371 case SG_EMULATED_HOST:
372 case SCSI_IOCTL_SEND_COMMAND:
373 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
374 case SG_IO:
375 return bsg_sg_io(bd->queue, file->f_mode, uarg);
376 default:
377 return -ENOTTY;
378 }
379 }
380
381 static const struct file_operations bsg_fops = {
382 .open = bsg_open,
383 .release = bsg_release,
384 .unlocked_ioctl = bsg_ioctl,
385 .owner = THIS_MODULE,
386 .llseek = default_llseek,
387 };
388
bsg_unregister_queue(struct request_queue * q)389 void bsg_unregister_queue(struct request_queue *q)
390 {
391 struct bsg_class_device *bcd = &q->bsg_dev;
392
393 if (!bcd->class_dev)
394 return;
395
396 mutex_lock(&bsg_mutex);
397 idr_remove(&bsg_minor_idr, bcd->minor);
398 if (q->kobj.sd)
399 sysfs_remove_link(&q->kobj, "bsg");
400 device_unregister(bcd->class_dev);
401 bcd->class_dev = NULL;
402 mutex_unlock(&bsg_mutex);
403 }
404 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
405
bsg_register_queue(struct request_queue * q,struct device * parent,const char * name,const struct bsg_ops * ops)406 int bsg_register_queue(struct request_queue *q, struct device *parent,
407 const char *name, const struct bsg_ops *ops)
408 {
409 struct bsg_class_device *bcd;
410 dev_t dev;
411 int ret;
412 struct device *class_dev = NULL;
413
414 /*
415 * we need a proper transport to send commands, not a stacked device
416 */
417 if (!queue_is_mq(q))
418 return 0;
419
420 bcd = &q->bsg_dev;
421 memset(bcd, 0, sizeof(*bcd));
422
423 mutex_lock(&bsg_mutex);
424
425 ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
426 if (ret < 0) {
427 if (ret == -ENOSPC) {
428 printk(KERN_ERR "bsg: too many bsg devices\n");
429 ret = -EINVAL;
430 }
431 goto unlock;
432 }
433
434 bcd->minor = ret;
435 bcd->queue = q;
436 bcd->ops = ops;
437 dev = MKDEV(bsg_major, bcd->minor);
438 class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name);
439 if (IS_ERR(class_dev)) {
440 ret = PTR_ERR(class_dev);
441 goto idr_remove;
442 }
443 bcd->class_dev = class_dev;
444
445 if (q->kobj.sd) {
446 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
447 if (ret)
448 goto unregister_class_dev;
449 }
450
451 mutex_unlock(&bsg_mutex);
452 return 0;
453
454 unregister_class_dev:
455 device_unregister(class_dev);
456 idr_remove:
457 idr_remove(&bsg_minor_idr, bcd->minor);
458 unlock:
459 mutex_unlock(&bsg_mutex);
460 return ret;
461 }
462
bsg_scsi_register_queue(struct request_queue * q,struct device * parent)463 int bsg_scsi_register_queue(struct request_queue *q, struct device *parent)
464 {
465 if (!blk_queue_scsi_passthrough(q)) {
466 WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
467 return -EINVAL;
468 }
469
470 return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops);
471 }
472 EXPORT_SYMBOL_GPL(bsg_scsi_register_queue);
473
474 static struct cdev bsg_cdev;
475
bsg_devnode(struct device * dev,umode_t * mode)476 static char *bsg_devnode(struct device *dev, umode_t *mode)
477 {
478 return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
479 }
480
bsg_init(void)481 static int __init bsg_init(void)
482 {
483 int ret, i;
484 dev_t devid;
485
486 for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
487 INIT_HLIST_HEAD(&bsg_device_list[i]);
488
489 bsg_class = class_create(THIS_MODULE, "bsg");
490 if (IS_ERR(bsg_class))
491 return PTR_ERR(bsg_class);
492 bsg_class->devnode = bsg_devnode;
493
494 ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
495 if (ret)
496 goto destroy_bsg_class;
497
498 bsg_major = MAJOR(devid);
499
500 cdev_init(&bsg_cdev, &bsg_fops);
501 ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
502 if (ret)
503 goto unregister_chrdev;
504
505 printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
506 " loaded (major %d)\n", bsg_major);
507 return 0;
508 unregister_chrdev:
509 unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
510 destroy_bsg_class:
511 class_destroy(bsg_class);
512 return ret;
513 }
514
515 MODULE_AUTHOR("Jens Axboe");
516 MODULE_DESCRIPTION(BSG_DESCRIPTION);
517 MODULE_LICENSE("GPL");
518
519 device_initcall(bsg_init);
520
