drivers/mtd/ubi/cdev.c

   1 /*
   2  * Copyright (c) International Business Machines Corp., 2006
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  12  * the GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  17  *
  18  * Author: Artem Bityutskiy (Битюцкий Артём)
  19  */
  20
  21 /*
  22  * This file includes implementation of UBI character device operations.
  23  *
  24  * There are two kinds of character devices in UBI: UBI character devices and
  25  * UBI volume character devices. UBI character devices allow users to
  26  * manipulate whole volumes: create, remove, and re-size them. Volume character
  27  * devices provide volume I/O capabilities.
  28  *
  29  * Major and minor numbers are assigned dynamically to both UBI and volume
  30  * character devices.
  31  */
  32
  33 #include <linux/module.h>
  34 #include <linux/stat.h>
  35 #include <linux/ioctl.h>
  36 #include <linux/capability.h>
  37 #include <mtd/ubi-user.h>
  38 #include <asm/uaccess.h>
  39 #include <asm/div64.h>
  40 #include "ubi.h"
  41
  42 /*
  43  * Maximum sequence numbers of UBI and volume character device IOCTLs (direct
  44  * logical eraseblock erase is a debug-only feature).
  45  */
  46 #define UBI_CDEV_IOC_MAX_SEQ 2
  47 #ifndef CONFIG_MTD_UBI_DEBUG_USERSPACE_IO
  48 #define VOL_CDEV_IOC_MAX_SEQ 1
  49 #else
  50 #define VOL_CDEV_IOC_MAX_SEQ 2
  51 #endif
  52
  53 /**
  54  * major_to_device - get UBI device object by character device major number.
  55  * @major: major number
  56  *
  57  * This function returns a pointer to the UBI device object.
  58  */
  59 static struct ubi_device *major_to_device(int major)
  60 {
  61         int i;
  62
  63         for (i = 0; i < ubi_devices_cnt; i++)
  64                 if (ubi_devices[i] && ubi_devices[i]->major == major)
  65                         return ubi_devices[i];
  66         BUG();
  67 }
  68
  69 /**
  70  * get_exclusive - get exclusive access to an UBI volume.
  71  * @desc: volume descriptor
  72  *
  73  * This function changes UBI volume open mode to "exclusive". Returns previous
  74  * mode value (positive integer) in case of success and a negative error code
  75  * in case of failure.
  76  */
  77 static int get_exclusive(struct ubi_volume_desc *desc)
  78 {
  79         int users, err;
  80         struct ubi_volume *vol = desc->vol;
  81
  82         spin_lock(&vol->ubi->volumes_lock);
  83         users = vol->readers + vol->writers + vol->exclusive;
  84         ubi_assert(users > 0);
  85         if (users > 1) {
  86                 dbg_err("%d users for volume %d", users, vol->vol_id);
  87                 err = -EBUSY;
  88         } else {
  89                 vol->readers = vol->writers = 0;
  90                 vol->exclusive = 1;
  91                 err = desc->mode;
  92                 desc->mode = UBI_EXCLUSIVE;
  93         }
  94         spin_unlock(&vol->ubi->volumes_lock);
  95
  96         return err;
  97 }
  98
  99 /**
 100  * revoke_exclusive - revoke exclusive mode.
 101  * @desc: volume descriptor
 102  * @mode: new mode to switch to
 103  */
 104 static void revoke_exclusive(struct ubi_volume_desc *desc, int mode)
 105 {
 106         struct ubi_volume *vol = desc->vol;
 107
 108         spin_lock(&vol->ubi->volumes_lock);
 109         ubi_assert(vol->readers == 0 && vol->writers == 0);
 110         ubi_assert(vol->exclusive == 1 && desc->mode == UBI_EXCLUSIVE);
 111         vol->exclusive = 0;
 112         if (mode == UBI_READONLY)
 113                 vol->readers = 1;
 114         else if (mode == UBI_READWRITE)
 115                 vol->writers = 1;
 116         else
 117                 vol->exclusive = 1;
 118         spin_unlock(&vol->ubi->volumes_lock);
 119
 120         desc->mode = mode;
 121 }
 122
 123 static int vol_cdev_open(struct inode *inode, struct file *file)
 124 {
 125         struct ubi_volume_desc *desc;
 126         const struct ubi_device *ubi = major_to_device(imajor(inode));
 127         int vol_id = iminor(inode) - 1;
 128         int mode;
 129
 130         if (file->f_mode & FMODE_WRITE)
 131                 mode = UBI_READWRITE;
 132         else
 133                 mode = UBI_READONLY;
 134
 135         dbg_msg("open volume %d, mode %d", vol_id, mode);
 136
 137         desc = ubi_open_volume(ubi->ubi_num, vol_id, mode);
 138         if (IS_ERR(desc))
 139                 return PTR_ERR(desc);
 140
 141         file->private_data = desc;
 142         return 0;
 143 }
 144
 145 static int vol_cdev_release(struct inode *inode, struct file *file)
 146 {
 147         struct ubi_volume_desc *desc = file->private_data;
 148         struct ubi_volume *vol = desc->vol;
 149
 150         dbg_msg("release volume %d, mode %d", vol->vol_id, desc->mode);
 151
 152         if (vol->updating) {
 153                 ubi_warn("update of volume %d not finished, volume is damaged",
 154                          vol->vol_id);
 155                 vol->updating = 0;
 156                 kfree(vol->upd_buf);
 157         }
 158
 159         ubi_close_volume(desc);
 160         return 0;
 161 }
 162
 163 static loff_t vol_cdev_llseek(struct file *file, loff_t offset, int origin)
 164 {
 165         struct ubi_volume_desc *desc = file->private_data;
 166         struct ubi_volume *vol = desc->vol;
 167         loff_t new_offset;
 168
 169         if (vol->updating) {
 170                  /* Update is in progress, seeking is prohibited */
 171                 dbg_err("updating");
 172                 return -EBUSY;
 173         }
 174
 175         switch (origin) {
 176         case 0: /* SEEK_SET */
 177                 new_offset = offset;
 178                 break;
 179         case 1: /* SEEK_CUR */
 180                 new_offset = file->f_pos + offset;
 181                 break;
 182         case 2: /* SEEK_END */
 183                 new_offset = vol->used_bytes + offset;
 184                 break;
 185         default:
 186                 return -EINVAL;
 187         }
 188
 189         if (new_offset < 0 || new_offset > vol->used_bytes) {
 190                 dbg_err("bad seek %lld", new_offset);
 191                 return -EINVAL;
 192         }
 193
 194         dbg_msg("seek volume %d, offset %lld, origin %d, new offset %lld",
 195                 vol->vol_id, offset, origin, new_offset);
 196
 197         file->f_pos = new_offset;
 198         return new_offset;
 199 }
 200
 201 static ssize_t vol_cdev_read(struct file *file, __user char *buf, size_t count,
 202                              loff_t *offp)
 203 {
 204         struct ubi_volume_desc *desc = file->private_data;
 205         struct ubi_volume *vol = desc->vol;
 206         struct ubi_device *ubi = vol->ubi;
 207         int err, lnum, off, len,  vol_id = desc->vol->vol_id, tbuf_size;
 208         size_t count_save = count;
 209         void *tbuf;
 210         uint64_t tmp;
 211
 212         dbg_msg("read %zd bytes from offset %lld of volume %d",
 213                 count, *offp, vol_id);
 214
 215         if (vol->updating) {
 216                 dbg_err("updating");
 217                 return -EBUSY;
 218         }
 219         if (vol->upd_marker) {
 220                 dbg_err("damaged volume, update marker is set");
 221                 return -EBADF;
 222         }
 223         if (*offp == vol->used_bytes || count == 0)
 224                 return 0;
 225
 226         if (vol->corrupted)
 227                 dbg_msg("read from corrupted volume %d", vol_id);
 228
 229         if (*offp + count > vol->used_bytes)
 230                 count_save = count = vol->used_bytes - *offp;
 231
 232         tbuf_size = vol->usable_leb_size;
 233         if (count < tbuf_size)
 234                 tbuf_size = ALIGN(count, ubi->min_io_size);
 235         tbuf = kmalloc(tbuf_size, GFP_KERNEL);
 236         if (!tbuf)
 237                 return -ENOMEM;
 238
 239         len = count > tbuf_size ? tbuf_size : count;
 240
 241         tmp = *offp;
 242         off = do_div(tmp, vol->usable_leb_size);
 243         lnum = tmp;
 244
 245         do {
 246                 cond_resched();
 247
 248                 if (off + len >= vol->usable_leb_size)
 249                         len = vol->usable_leb_size - off;
 250
 251                 err = ubi_eba_read_leb(ubi, vol_id, lnum, tbuf, off, len, 0);
 252                 if (err)
 253                         break;
 254
 255                 off += len;
 256                 if (off == vol->usable_leb_size) {
 257                         lnum += 1;
 258                         off -= vol->usable_leb_size;
 259                 }
 260
 261                 count -= len;
 262                 *offp += len;
 263
 264                 err = copy_to_user(buf, tbuf, len);
 265                 if (err) {
 266                         err = -EFAULT;
 267                         break;
 268                 }
 269
 270                 buf += len;
 271                 len = count > tbuf_size ? tbuf_size : count;
 272         } while (count);
 273
 274         kfree(tbuf);
 275         return err ? err : count_save - count;
 276 }
 277
 278 #ifdef CONFIG_MTD_UBI_DEBUG_USERSPACE_IO
 279
 280 /*
 281  * This function allows to directly write to dynamic UBI volumes, without
 282  * issuing the volume update operation. Available only as a debugging feature.
 283  * Very useful for testing UBI.
 284  */
 285 static ssize_t vol_cdev_direct_write(struct file *file, const char __user *buf,
 286                                      size_t count, loff_t *offp)
 287 {
 288         struct ubi_volume_desc *desc = file->private_data;
 289         struct ubi_volume *vol = desc->vol;
 290         struct ubi_device *ubi = vol->ubi;
 291         int lnum, off, len, tbuf_size, vol_id = vol->vol_id, err = 0;
 292         size_t count_save = count;
 293         char *tbuf;
 294         uint64_t tmp;
 295
 296         dbg_msg("requested: write %zd bytes to offset %lld of volume %u",
 297                 count, *offp, desc->vol->vol_id);
 298
 299         if (vol->vol_type == UBI_STATIC_VOLUME)
 300                 return -EROFS;
 301
 302         tmp = *offp;
 303         off = do_div(tmp, vol->usable_leb_size);
 304         lnum = tmp;
 305
 306         if (off % ubi->min_io_size) {
 307                 dbg_err("unaligned position");
 308                 return -EINVAL;
 309         }
 310
 311         if (*offp + count > vol->used_bytes)
 312                 count_save = count = vol->used_bytes - *offp;
 313
 314         /* We can write only in fractions of the minimum I/O unit */
 315         if (count % ubi->min_io_size) {
 316                 dbg_err("unaligned write length");
 317                 return -EINVAL;
 318         }
 319
 320         tbuf_size = vol->usable_leb_size;
 321         if (count < tbuf_size)
 322                 tbuf_size = ALIGN(count, ubi->min_io_size);
 323         tbuf = kmalloc(tbuf_size, GFP_KERNEL);
 324         if (!tbuf)
 325                 return -ENOMEM;
 326
 327         len = count > tbuf_size ? tbuf_size : count;
 328
 329         while (count) {
 330                 cond_resched();
 331
 332                 if (off + len >= vol->usable_leb_size)
 333                         len = vol->usable_leb_size - off;
 334
 335                 err = copy_from_user(tbuf, buf, len);
 336                 if (err) {
 337                         err = -EFAULT;
 338                         break;
 339                 }
 340
 341                 err = ubi_eba_write_leb(ubi, vol_id, lnum, tbuf, off, len,
 342                                         UBI_UNKNOWN);
 343                 if (err)
 344                         break;
 345
 346                 off += len;
 347                 if (off == vol->usable_leb_size) {
 348                         lnum += 1;
 349                         off -= vol->usable_leb_size;
 350                 }
 351
 352                 count -= len;
 353                 *offp += len;
 354                 buf += len;
 355                 len = count > tbuf_size ? tbuf_size : count;
 356         }
 357
 358         kfree(tbuf);
 359         return err ? err : count_save - count;
 360 }
 361
 362 #else
 363 #define vol_cdev_direct_write(file, buf, count, offp) -EPERM
 364 #endif /* CONFIG_MTD_UBI_DEBUG_USERSPACE_IO */
 365
 366 static ssize_t vol_cdev_write(struct file *file, const char __user *buf,
 367                               size_t count, loff_t *offp)
 368 {
 369         int err = 0;
 370         struct ubi_volume_desc *desc = file->private_data;
 371         struct ubi_volume *vol = desc->vol;
 372         struct ubi_device *ubi = vol->ubi;
 373
 374         if (!vol->updating)
 375                 return vol_cdev_direct_write(file, buf, count, offp);
 376
 377         err = ubi_more_update_data(ubi, vol->vol_id, buf, count);
 378         if (err < 0) {
 379                 ubi_err("cannot write %zd bytes of update data", count);
 380                 return err;
 381         }
 382
 383         if (err) {
 384                 /*
 385                  * Update is finished, @err contains number of actually written
 386                  * bytes now.
 387                  */
 388                 count = err;
 389
 390                 err = ubi_check_volume(ubi, vol->vol_id);
 391                 if (err < 0)
 392                         return err;
 393
 394                 if (err) {
 395                         ubi_warn("volume %d on UBI device %d is corrupted",
 396                                  vol->vol_id, ubi->ubi_num);
 397                         vol->corrupted = 1;
 398                 }
 399                 vol->checked = 1;
 400                 revoke_exclusive(desc, UBI_READWRITE);
 401         }
 402
 403         *offp += count;
 404         return count;
 405 }
 406
 407 static int vol_cdev_ioctl(struct inode *inode, struct file *file,
 408                           unsigned int cmd, unsigned long arg)
 409 {
 410         int err = 0;
 411         struct ubi_volume_desc *desc = file->private_data;
 412         struct ubi_volume *vol = desc->vol;
 413         struct ubi_device *ubi = vol->ubi;
 414         void __user *argp = (void __user *)arg;
 415
 416         if (_IOC_NR(cmd) > VOL_CDEV_IOC_MAX_SEQ ||
 417             _IOC_TYPE(cmd) != UBI_VOL_IOC_MAGIC)
 418                 return -ENOTTY;
 419
 420         if (_IOC_DIR(cmd) && _IOC_READ)
 421                 err = !access_ok(VERIFY_WRITE, argp, _IOC_SIZE(cmd));
 422         else if (_IOC_DIR(cmd) && _IOC_WRITE)
 423                 err = !access_ok(VERIFY_READ, argp, _IOC_SIZE(cmd));
 424         if (err)
 425                 return -EFAULT;
 426
 427         switch (cmd) {
 428
 429         /* Volume update command */
 430         case UBI_IOCVOLUP:
 431         {
 432                 int64_t bytes, rsvd_bytes;
 433
 434                 if (!capable(CAP_SYS_RESOURCE)) {
 435                         err = -EPERM;
 436                         break;
 437                 }
 438
 439                 err = copy_from_user(&bytes, argp, sizeof(int64_t));
 440                 if (err) {
 441                         err = -EFAULT;
 442                         break;
 443                 }
 444
 445                 if (desc->mode == UBI_READONLY) {
 446                         err = -EROFS;
 447                         break;
 448                 }
 449
 450                 rsvd_bytes = vol->reserved_pebs * (ubi->leb_size-vol->data_pad);
 451                 if (bytes < 0 || bytes > rsvd_bytes) {
 452                         err = -EINVAL;
 453                         break;
 454                 }
 455
 456                 err = get_exclusive(desc);
 457                 if (err < 0)
 458                         break;
 459
 460                 err = ubi_start_update(ubi, vol->vol_id, bytes);
 461                 if (bytes == 0)
 462                         revoke_exclusive(desc, UBI_READWRITE);
 463
 464                 file->f_pos = 0;
 465                 break;
 466         }
 467
 468 #ifdef CONFIG_MTD_UBI_DEBUG_USERSPACE_IO
 469         /* Logical eraseblock erasure command */
 470         case UBI_IOCEBER:
 471         {
 472                 int32_t lnum;
 473
 474                 err = __get_user(lnum, (__user int32_t *)argp);
 475                 if (err) {
 476                         err = -EFAULT;
 477                         break;
 478                 }
 479
 480                 if (desc->mode == UBI_READONLY) {
 481                         err = -EROFS;
 482                         break;
 483                 }
 484
 485                 if (lnum < 0 || lnum >= vol->reserved_pebs) {
 486                         err = -EINVAL;
 487                         break;
 488                 }
 489
 490                 if (vol->vol_type != UBI_DYNAMIC_VOLUME) {
 491                         err = -EROFS;
 492                         break;
 493                 }
 494
 495                 dbg_msg("erase LEB %d:%d", vol->vol_id, lnum);
 496                 err = ubi_eba_unmap_leb(ubi, vol->vol_id, lnum);
 497                 if (err)
 498                         break;
 499
 500                 err = ubi_wl_flush(ubi);
 501                 break;
 502         }
 503 #endif
 504
 505         default:
 506                 err = -ENOTTY;
 507                 break;
 508         }
 509
 510         return err;
 511 }
 512
 513 /**
 514  * verify_mkvol_req - verify volume creation request.
 515  * @ubi: UBI device description object
 516  * @req: the request to check
 517  *
 518  * This function zero if the request is correct, and %-EINVAL if not.
 519  */
 520 static int verify_mkvol_req(const struct ubi_device *ubi,
 521                             const struct ubi_mkvol_req *req)
 522 {
 523         int n, err = -EINVAL;
 524
 525         if (req->bytes < 0 || req->alignment < 0 || req->vol_type < 0 ||
 526             req->name_len < 0)
 527                 goto bad;
 528
 529         if ((req->vol_id < 0 || req->vol_id >= ubi->vtbl_slots) &&
 530             req->vol_id != UBI_VOL_NUM_AUTO)
 531                 goto bad;
 532
 533         if (req->alignment == 0)
 534                 goto bad;
 535
 536         if (req->bytes == 0)
 537                 goto bad;
 538
 539         if (req->vol_type != UBI_DYNAMIC_VOLUME &&
 540             req->vol_type != UBI_STATIC_VOLUME)
 541                 goto bad;
 542
 543         if (req->alignment > ubi->leb_size)
 544                 goto bad;
 545
 546         n = req->alignment % ubi->min_io_size;
 547         if (req->alignment != 1 && n)
 548                 goto bad;
 549
 550         if (req->name_len > UBI_VOL_NAME_MAX) {
 551                 err = -ENAMETOOLONG;
 552                 goto bad;
 553         }
 554
 555         return 0;
 556
 557 bad:
 558         dbg_err("bad volume creation request");
 559         ubi_dbg_dump_mkvol_req(req);
 560         return err;
 561 }
 562
 563 /**
 564  * verify_rsvol_req - verify volume re-size request.
 565  * @ubi: UBI device description object
 566  * @req: the request to check
 567  *
 568  * This function returns zero if the request is correct, and %-EINVAL if not.
 569  */
 570 static int verify_rsvol_req(const struct ubi_device *ubi,
 571                             const struct ubi_rsvol_req *req)
 572 {
 573         if (req->bytes <= 0)
 574                 return -EINVAL;
 575
 576         if (req->vol_id < 0 || req->vol_id >= ubi->vtbl_slots)
 577                 return -EINVAL;
 578
 579         return 0;
 580 }
 581
 582 static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
 583                           unsigned int cmd, unsigned long arg)
 584 {
 585         int err = 0;
 586         struct ubi_device *ubi;
 587         struct ubi_volume_desc *desc;
 588         void __user *argp = (void __user *)arg;
 589
 590         if (_IOC_NR(cmd) > UBI_CDEV_IOC_MAX_SEQ ||
 591             _IOC_TYPE(cmd) != UBI_IOC_MAGIC)
 592                 return -ENOTTY;
 593
 594         if (_IOC_DIR(cmd) && _IOC_READ)
 595                 err = !access_ok(VERIFY_WRITE, argp, _IOC_SIZE(cmd));
 596         else if (_IOC_DIR(cmd) && _IOC_WRITE)
 597                 err = !access_ok(VERIFY_READ, argp, _IOC_SIZE(cmd));
 598         if (err)
 599                 return -EFAULT;
 600
 601         if (!capable(CAP_SYS_RESOURCE))
 602                 return -EPERM;
 603
 604         ubi = major_to_device(imajor(inode));
 605         if (IS_ERR(ubi))
 606                 return PTR_ERR(ubi);
 607
 608         switch (cmd) {
 609         /* Create volume command */
 610         case UBI_IOCMKVOL:
 611         {
 612                 struct ubi_mkvol_req req;
 613
 614                 dbg_msg("create volume");
 615                 err = __copy_from_user(&req, argp,
 616                                        sizeof(struct ubi_mkvol_req));
 617                 if (err) {
 618                         err = -EFAULT;
 619                         break;
 620                 }
 621
 622                 err = verify_mkvol_req(ubi, &req);
 623                 if (err)
 624                         break;
 625
 626                 req.name[req.name_len] = '\0';
 627
 628                 err = ubi_create_volume(ubi, &req);
 629                 if (err)
 630                         break;
 631
 632                 err = __put_user(req.vol_id, (__user int32_t *)argp);
 633                 if (err)
 634                         err = -EFAULT;
 635
 636                 break;
 637         }
 638
 639         /* Remove volume command */
 640         case UBI_IOCRMVOL:
 641         {
 642                 int vol_id;
 643
 644                 dbg_msg("remove volume");
 645                 err = __get_user(vol_id, (__user int32_t *)argp);
 646                 if (err) {
 647                         err = -EFAULT;
 648                         break;
 649                 }
 650
 651                 desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_EXCLUSIVE);
 652                 if (IS_ERR(desc)) {
 653                         err = PTR_ERR(desc);
 654                         break;
 655                 }
 656
 657                 err = ubi_remove_volume(desc);
 658                 if (err)
 659                         ubi_close_volume(desc);
 660
 661                 break;
 662         }
 663
 664         /* Re-size volume command */
 665         case UBI_IOCRSVOL:
 666         {
 667                 int pebs;
 668                 uint64_t tmp;
 669                 struct ubi_rsvol_req req;
 670
 671                 dbg_msg("re-size volume");
 672                 err = __copy_from_user(&req, argp,
 673                                        sizeof(struct ubi_rsvol_req));
 674                 if (err) {
 675                         err = -EFAULT;
 676                         break;
 677                 }
 678
 679                 err = verify_rsvol_req(ubi, &req);
 680                 if (err)
 681                         break;
 682
 683                 desc = ubi_open_volume(ubi->ubi_num, req.vol_id, UBI_EXCLUSIVE);
 684                 if (IS_ERR(desc)) {
 685                         err = PTR_ERR(desc);
 686                         break;
 687                 }
 688
 689                 tmp = req.bytes;
 690                 pebs = !!do_div(tmp, desc->vol->usable_leb_size);
 691                 pebs += tmp;
 692
 693                 err = ubi_resize_volume(desc, pebs);
 694                 ubi_close_volume(desc);
 695                 break;
 696         }
 697
 698         default:
 699                 err = -ENOTTY;
 700                 break;
 701         }
 702
 703         return err;
 704 }
 705
 706 /* UBI character device operations */
 707 struct file_operations ubi_cdev_operations = {
 708         .owner = THIS_MODULE,
 709         .ioctl = ubi_cdev_ioctl,
 710         .llseek = no_llseek
 711 };
 712
 713 /* UBI volume character device operations */
 714 struct file_operations ubi_vol_cdev_operations = {
 715         .owner   = THIS_MODULE,
 716         .open    = vol_cdev_open,
 717         .release = vol_cdev_release,
 718         .llseek  = vol_cdev_llseek,
 719         .read    = vol_cdev_read,
 720         .write   = vol_cdev_write,
 721         .ioctl   = vol_cdev_ioctl
 722 };