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 #include <linux/pm_runtime.h>
16
17 #include <scsi/scsi.h>
18 #include <scsi/scsi_ioctl.h>
19 #include <scsi/scsi_cmnd.h>
20 #include <scsi/scsi_device.h>
21 #include <scsi/scsi_driver.h>
22 #include <scsi/sg.h>
23
24 #define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
25 #define BSG_VERSION "0.4"
26
27 #define bsg_dbg(bd, fmt, ...) \
28 pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__)
29
30 struct bsg_device {
31 struct request_queue *queue;
32 spinlock_t lock;
33 struct hlist_node dev_list;
34 refcount_t ref_count;
35 char name[20];
36 int max_queue;
37 };
38
39 #define BSG_DEFAULT_CMDS 64
40 #define BSG_MAX_DEVS 32768
41
42 static DEFINE_MUTEX(bsg_mutex);
43 static DEFINE_IDR(bsg_minor_idr);
44
45 #define BSG_LIST_ARRAY_SIZE 8
46 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
47
48 static struct class *bsg_class;
49 static int bsg_major;
50
bsg_dev_idx_hash(int index)51 static inline struct hlist_head *bsg_dev_idx_hash(int index)
52 {
53 return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
54 }
55
56 #define uptr64(val) ((void __user *)(uintptr_t)(val))
57
bsg_scsi_check_proto(struct sg_io_v4 * hdr)58 static int bsg_scsi_check_proto(struct sg_io_v4 *hdr)
59 {
60 if (hdr->protocol != BSG_PROTOCOL_SCSI ||
61 hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
62 return -EINVAL;
63 return 0;
64 }
65
bsg_scsi_fill_hdr(struct request * rq,struct sg_io_v4 * hdr,fmode_t mode)66 static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
67 fmode_t mode)
68 {
69 struct scsi_request *sreq = scsi_req(rq);
70
71 if (hdr->dout_xfer_len && hdr->din_xfer_len) {
72 pr_warn_once("BIDI support in bsg has been removed.\n");
73 return -EOPNOTSUPP;
74 }
75
76 sreq->cmd_len = hdr->request_len;
77 if (sreq->cmd_len > BLK_MAX_CDB) {
78 sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
79 if (!sreq->cmd)
80 return -ENOMEM;
81 }
82
83 if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
84 return -EFAULT;
85 if (blk_verify_command(sreq->cmd, mode))
86 return -EPERM;
87 return 0;
88 }
89
bsg_scsi_complete_rq(struct request * rq,struct sg_io_v4 * hdr)90 static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
91 {
92 struct scsi_request *sreq = scsi_req(rq);
93 int ret = 0;
94
95 /*
96 * fill in all the output members
97 */
98 hdr->device_status = sreq->result & 0xff;
99 hdr->transport_status = host_byte(sreq->result);
100 hdr->driver_status = driver_byte(sreq->result);
101 hdr->info = 0;
102 if (hdr->device_status || hdr->transport_status || hdr->driver_status)
103 hdr->info |= SG_INFO_CHECK;
104 hdr->response_len = 0;
105
106 if (sreq->sense_len && hdr->response) {
107 int len = min_t(unsigned int, hdr->max_response_len,
108 sreq->sense_len);
109
110 if (copy_to_user(uptr64(hdr->response), sreq->sense, len))
111 ret = -EFAULT;
112 else
113 hdr->response_len = len;
114 }
115
116 if (rq_data_dir(rq) == READ)
117 hdr->din_resid = sreq->resid_len;
118 else
119 hdr->dout_resid = sreq->resid_len;
120
121 return ret;
122 }
123
bsg_scsi_free_rq(struct request * rq)124 static void bsg_scsi_free_rq(struct request *rq)
125 {
126 scsi_req_free_cmd(scsi_req(rq));
127 }
128
129 static const struct bsg_ops bsg_scsi_ops = {
130 .check_proto = bsg_scsi_check_proto,
131 .fill_hdr = bsg_scsi_fill_hdr,
132 .complete_rq = bsg_scsi_complete_rq,
133 .free_rq = bsg_scsi_free_rq,
134 };
135
bsg_sg_io(struct request_queue * q,fmode_t mode,void __user * uarg)136 static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
137 {
138 struct request *rq;
139 struct bio *bio;
140 struct sg_io_v4 hdr;
141 int ret;
142
143 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
144 return -EFAULT;
145
146 if (!q->bsg_dev.class_dev)
147 return -ENXIO;
148
149 if (hdr.guard != 'Q')
150 return -EINVAL;
151 ret = q->bsg_dev.ops->check_proto(&hdr);
152 if (ret)
153 return ret;
154
155 rq = blk_get_request(q, hdr.dout_xfer_len ?
156 REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);
157 if (IS_ERR(rq))
158 return PTR_ERR(rq);
159
160 ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode);
161 if (ret) {
162 blk_put_request(rq);
163 return ret;
164 }
165
166 rq->timeout = msecs_to_jiffies(hdr.timeout);
167 if (!rq->timeout)
168 rq->timeout = q->sg_timeout;
169 if (!rq->timeout)
170 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
171 if (rq->timeout < BLK_MIN_SG_TIMEOUT)
172 rq->timeout = BLK_MIN_SG_TIMEOUT;
173
174 if (hdr.dout_xfer_len) {
175 ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp),
176 hdr.dout_xfer_len, GFP_KERNEL);
177 } else if (hdr.din_xfer_len) {
178 ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.din_xferp),
179 hdr.din_xfer_len, GFP_KERNEL);
180 }
181
182 if (ret)
183 goto out_free_rq;
184
185 bio = rq->bio;
186
187 blk_execute_rq(q, NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL));
188 ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr);
189 blk_rq_unmap_user(bio);
190
191 out_free_rq:
192 rq->q->bsg_dev.ops->free_rq(rq);
193 blk_put_request(rq);
194 if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
195 return -EFAULT;
196 return ret;
197 }
198
bsg_alloc_device(void)199 static struct bsg_device *bsg_alloc_device(void)
200 {
201 struct bsg_device *bd;
202
203 bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
204 if (unlikely(!bd))
205 return NULL;
206
207 spin_lock_init(&bd->lock);
208 bd->max_queue = BSG_DEFAULT_CMDS;
209 INIT_HLIST_NODE(&bd->dev_list);
210 return bd;
211 }
212
bsg_put_device(struct bsg_device * bd)213 static int bsg_put_device(struct bsg_device *bd)
214 {
215 struct request_queue *q = bd->queue;
216
217 mutex_lock(&bsg_mutex);
218
219 if (!refcount_dec_and_test(&bd->ref_count)) {
220 mutex_unlock(&bsg_mutex);
221 return 0;
222 }
223
224 hlist_del(&bd->dev_list);
225 mutex_unlock(&bsg_mutex);
226
227 bsg_dbg(bd, "tearing down\n");
228
229 /*
230 * close can always block
231 */
232 kfree(bd);
233 blk_put_queue(q);
234 return 0;
235 }
236
bsg_add_device(struct inode * inode,struct request_queue * rq,struct file * file)237 static struct bsg_device *bsg_add_device(struct inode *inode,
238 struct request_queue *rq,
239 struct file *file)
240 {
241 struct bsg_device *bd;
242 unsigned char buf[32];
243
244 lockdep_assert_held(&bsg_mutex);
245
246 if (!blk_get_queue(rq))
247 return ERR_PTR(-ENXIO);
248
249 bd = bsg_alloc_device();
250 if (!bd) {
251 blk_put_queue(rq);
252 return ERR_PTR(-ENOMEM);
253 }
254
255 bd->queue = rq;
256
257 refcount_set(&bd->ref_count, 1);
258 hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
259
260 strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
261 bsg_dbg(bd, "bound to <%s>, max queue %d\n",
262 format_dev_t(buf, inode->i_rdev), bd->max_queue);
263
264 return bd;
265 }
266
__bsg_get_device(int minor,struct request_queue * q)267 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
268 {
269 struct bsg_device *bd;
270
271 lockdep_assert_held(&bsg_mutex);
272
273 hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
274 if (bd->queue == q) {
275 refcount_inc(&bd->ref_count);
276 goto found;
277 }
278 }
279 bd = NULL;
280 found:
281 return bd;
282 }
283
bsg_get_device(struct inode * inode,struct file * file)284 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
285 {
286 struct bsg_device *bd;
287 struct bsg_class_device *bcd;
288
289 /*
290 * find the class device
291 */
292 mutex_lock(&bsg_mutex);
293 bcd = idr_find(&bsg_minor_idr, iminor(inode));
294
295 if (!bcd) {
296 bd = ERR_PTR(-ENODEV);
297 goto out_unlock;
298 }
299
300 bd = __bsg_get_device(iminor(inode), bcd->queue);
301 if (!bd)
302 bd = bsg_add_device(inode, bcd->queue, file);
303
304 out_unlock:
305 mutex_unlock(&bsg_mutex);
306 return bd;
307 }
308
bsg_open(struct inode * inode,struct file * file)309 static int bsg_open(struct inode *inode, struct file *file)
310 {
311 struct bsg_device *bd;
312 struct bsg_class_device *bcd;
313
314 bd = bsg_get_device(inode, file);
315
316 if (IS_ERR(bd))
317 return PTR_ERR(bd);
318
319 bcd = &bd->queue->bsg_dev;
320 pm_runtime_get_sync(bcd->class_dev->parent);
321 file->private_data = bd;
322 return 0;
323 }
324
bsg_release(struct inode * inode,struct file * file)325 static int bsg_release(struct inode *inode, struct file *file)
326 {
327 struct bsg_device *bd = file->private_data;
328 struct bsg_class_device *bcd;
329
330 file->private_data = NULL;
331
332 bcd = &bd->queue->bsg_dev;
333 pm_runtime_put_sync(bcd->class_dev->parent);
334 return bsg_put_device(bd);
335 }
336
bsg_get_command_q(struct bsg_device * bd,int __user * uarg)337 static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
338 {
339 return put_user(bd->max_queue, uarg);
340 }
341
bsg_set_command_q(struct bsg_device * bd,int __user * uarg)342 static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
343 {
344 int queue;
345
346 if (get_user(queue, uarg))
347 return -EFAULT;
348 if (queue < 1)
349 return -EINVAL;
350
351 spin_lock_irq(&bd->lock);
352 bd->max_queue = queue;
353 spin_unlock_irq(&bd->lock);
354 return 0;
355 }
356
bsg_ioctl(struct file * file,unsigned int cmd,unsigned long arg)357 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
358 {
359 struct bsg_device *bd = file->private_data;
360 void __user *uarg = (void __user *) arg;
361
362 switch (cmd) {
363 /*
364 * Our own ioctls
365 */
366 case SG_GET_COMMAND_Q:
367 return bsg_get_command_q(bd, uarg);
368 case SG_SET_COMMAND_Q:
369 return bsg_set_command_q(bd, uarg);
370
371 /*
372 * SCSI/sg ioctls
373 */
374 case SG_GET_VERSION_NUM:
375 case SCSI_IOCTL_GET_IDLUN:
376 case SCSI_IOCTL_GET_BUS_NUMBER:
377 case SG_SET_TIMEOUT:
378 case SG_GET_TIMEOUT:
379 case SG_GET_RESERVED_SIZE:
380 case SG_SET_RESERVED_SIZE:
381 case SG_EMULATED_HOST:
382 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
383 case SG_IO:
384 return bsg_sg_io(bd->queue, file->f_mode, uarg);
385 case SCSI_IOCTL_SEND_COMMAND:
386 pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n",
387 current->comm);
388 return -EINVAL;
389 default:
390 return -ENOTTY;
391 }
392 }
393
394 static const struct file_operations bsg_fops = {
395 .open = bsg_open,
396 .release = bsg_release,
397 .unlocked_ioctl = bsg_ioctl,
398 .compat_ioctl = compat_ptr_ioctl,
399 .owner = THIS_MODULE,
400 .llseek = default_llseek,
401 };
402
bsg_unregister_queue(struct request_queue * q)403 void bsg_unregister_queue(struct request_queue *q)
404 {
405 struct bsg_class_device *bcd = &q->bsg_dev;
406
407 if (!bcd->class_dev)
408 return;
409
410 mutex_lock(&bsg_mutex);
411 idr_remove(&bsg_minor_idr, bcd->minor);
412 if (q->kobj.sd)
413 sysfs_remove_link(&q->kobj, "bsg");
414 device_unregister(bcd->class_dev);
415 bcd->class_dev = NULL;
416 mutex_unlock(&bsg_mutex);
417 }
418 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
419
bsg_register_queue(struct request_queue * q,struct device * parent,const char * name,const struct bsg_ops * ops)420 int bsg_register_queue(struct request_queue *q, struct device *parent,
421 const char *name, const struct bsg_ops *ops)
422 {
423 struct bsg_class_device *bcd;
424 dev_t dev;
425 int ret;
426 struct device *class_dev = NULL;
427
428 /*
429 * we need a proper transport to send commands, not a stacked device
430 */
431 if (!queue_is_mq(q))
432 return 0;
433
434 bcd = &q->bsg_dev;
435 memset(bcd, 0, sizeof(*bcd));
436
437 mutex_lock(&bsg_mutex);
438
439 ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
440 if (ret < 0) {
441 if (ret == -ENOSPC) {
442 printk(KERN_ERR "bsg: too many bsg devices\n");
443 ret = -EINVAL;
444 }
445 goto unlock;
446 }
447
448 bcd->minor = ret;
449 bcd->queue = q;
450 bcd->ops = ops;
451 dev = MKDEV(bsg_major, bcd->minor);
452 class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name);
453 if (IS_ERR(class_dev)) {
454 ret = PTR_ERR(class_dev);
455 goto idr_remove;
456 }
457 bcd->class_dev = class_dev;
458
459 if (q->kobj.sd) {
460 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
461 if (ret)
462 goto unregister_class_dev;
463 }
464
465 mutex_unlock(&bsg_mutex);
466 return 0;
467
468 unregister_class_dev:
469 device_unregister(class_dev);
470 idr_remove:
471 idr_remove(&bsg_minor_idr, bcd->minor);
472 unlock:
473 mutex_unlock(&bsg_mutex);
474 return ret;
475 }
476
bsg_scsi_register_queue(struct request_queue * q,struct device * parent)477 int bsg_scsi_register_queue(struct request_queue *q, struct device *parent)
478 {
479 if (!blk_queue_scsi_passthrough(q)) {
480 WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
481 return -EINVAL;
482 }
483
484 return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops);
485 }
486 EXPORT_SYMBOL_GPL(bsg_scsi_register_queue);
487
488 static struct cdev bsg_cdev;
489
bsg_devnode(struct device * dev,umode_t * mode)490 static char *bsg_devnode(struct device *dev, umode_t *mode)
491 {
492 return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
493 }
494
bsg_init(void)495 static int __init bsg_init(void)
496 {
497 int ret, i;
498 dev_t devid;
499
500 for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
501 INIT_HLIST_HEAD(&bsg_device_list[i]);
502
503 bsg_class = class_create(THIS_MODULE, "bsg");
504 if (IS_ERR(bsg_class))
505 return PTR_ERR(bsg_class);
506 bsg_class->devnode = bsg_devnode;
507
508 ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
509 if (ret)
510 goto destroy_bsg_class;
511
512 bsg_major = MAJOR(devid);
513
514 cdev_init(&bsg_cdev, &bsg_fops);
515 ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
516 if (ret)
517 goto unregister_chrdev;
518
519 printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
520 " loaded (major %d)\n", bsg_major);
521 return 0;
522 unregister_chrdev:
523 unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
524 destroy_bsg_class:
525 class_destroy(bsg_class);
526 return ret;
527 }
528
529 MODULE_AUTHOR("Jens Axboe");
530 MODULE_DESCRIPTION(BSG_DESCRIPTION);
531 MODULE_LICENSE("GPL");
532
533 device_initcall(bsg_init);
534