block/bsg.c

   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 = 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 476 static char *bsg_devnode(struct device *dev, umode_t *mode)
 477 {
 478         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
 479 }
 480
 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);