| 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); |