fs/ioctl.c

   1 /*
   2  *  linux/fs/ioctl.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/syscalls.h>
   8 #include <linux/mm.h>
   9 #include <linux/smp_lock.h>
  10 #include <linux/capability.h>
  11 #include <linux/file.h>
  12 #include <linux/fs.h>
  13 #include <linux/security.h>
  14 #include <linux/module.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/writeback.h>
  17 #include <linux/buffer_head.h>
  18
  19 #include <asm/ioctls.h>
  20
  21 /* So that the fiemap access checks can't overflow on 32 bit machines. */
  22 #define FIEMAP_MAX_EXTENTS      (UINT_MAX / sizeof(struct fiemap_extent))
  23
  24 /**
  25  * vfs_ioctl - call filesystem specific ioctl methods
  26  * @filp:       open file to invoke ioctl method on
  27  * @cmd:        ioctl command to execute
  28  * @arg:        command-specific argument for ioctl
  29  *
  30  * Invokes filesystem specific ->unlocked_ioctl, if one exists; otherwise
  31  * invokes filesystem specific ->ioctl method.  If neither method exists,
  32  * returns -ENOTTY.
  33  *
  34  * Returns 0 on success, -errno on error.
  35  */
  36 static long vfs_ioctl(struct file *filp, unsigned int cmd,
  37                       unsigned long arg)
  38 {
  39         int error = -ENOTTY;
  40
  41         if (!filp->f_op)
  42                 goto out;
  43
  44         if (filp->f_op->unlocked_ioctl) {
  45                 error = filp->f_op->unlocked_ioctl(filp, cmd, arg);
  46                 if (error == -ENOIOCTLCMD)
  47                         error = -EINVAL;
  48                 goto out;
  49         } else if (filp->f_op->ioctl) {
  50                 lock_kernel();
  51                 error = filp->f_op->ioctl(filp->f_path.dentry->d_inode,
  52                                           filp, cmd, arg);
  53                 unlock_kernel();
  54         }
  55
  56  out:
  57         return error;
  58 }
  59
  60 static int ioctl_fibmap(struct file *filp, int __user *p)
  61 {
  62         struct address_space *mapping = filp->f_mapping;
  63         int res, block;
  64
  65         /* do we support this mess? */
  66         if (!mapping->a_ops->bmap)
  67                 return -EINVAL;
  68         if (!capable(CAP_SYS_RAWIO))
  69                 return -EPERM;
  70         res = get_user(block, p);
  71         if (res)
  72                 return res;
  73         lock_kernel();
  74         res = mapping->a_ops->bmap(mapping, block);
  75         unlock_kernel();
  76         return put_user(res, p);
  77 }
  78
  79 /**
  80  * fiemap_fill_next_extent - Fiemap helper function
  81  * @fieinfo:    Fiemap context passed into ->fiemap
  82  * @logical:    Extent logical start offset, in bytes
  83  * @phys:       Extent physical start offset, in bytes
  84  * @len:        Extent length, in bytes
  85  * @flags:      FIEMAP_EXTENT flags that describe this extent
  86  *
  87  * Called from file system ->fiemap callback. Will populate extent
  88  * info as passed in via arguments and copy to user memory. On
  89  * success, extent count on fieinfo is incremented.
  90  *
  91  * Returns 0 on success, -errno on error, 1 if this was the last
  92  * extent that will fit in user array.
  93  */
  94 #define SET_UNKNOWN_FLAGS       (FIEMAP_EXTENT_DELALLOC)
  95 #define SET_NO_UNMOUNTED_IO_FLAGS       (FIEMAP_EXTENT_DATA_ENCRYPTED)
  96 #define SET_NOT_ALIGNED_FLAGS   (FIEMAP_EXTENT_DATA_TAIL|FIEMAP_EXTENT_DATA_INLINE)
  97 int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
  98                             u64 phys, u64 len, u32 flags)
  99 {
 100         struct fiemap_extent extent;
 101         struct fiemap_extent *dest = fieinfo->fi_extents_start;
 102
 103         /* only count the extents */
 104         if (fieinfo->fi_extents_max == 0) {
 105                 fieinfo->fi_extents_mapped++;
 106                 return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
 107         }
 108
 109         if (fieinfo->fi_extents_mapped >= fieinfo->fi_extents_max)
 110                 return 1;
 111
 112         if (flags & SET_UNKNOWN_FLAGS)
 113                 flags |= FIEMAP_EXTENT_UNKNOWN;
 114         if (flags & SET_NO_UNMOUNTED_IO_FLAGS)
 115                 flags |= FIEMAP_EXTENT_ENCODED;
 116         if (flags & SET_NOT_ALIGNED_FLAGS)
 117                 flags |= FIEMAP_EXTENT_NOT_ALIGNED;
 118
 119         memset(&extent, 0, sizeof(extent));
 120         extent.fe_logical = logical;
 121         extent.fe_physical = phys;
 122         extent.fe_length = len;
 123         extent.fe_flags = flags;
 124
 125         dest += fieinfo->fi_extents_mapped;
 126         if (copy_to_user(dest, &extent, sizeof(extent)))
 127                 return -EFAULT;
 128
 129         fieinfo->fi_extents_mapped++;
 130         if (fieinfo->fi_extents_mapped == fieinfo->fi_extents_max)
 131                 return 1;
 132         return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
 133 }
 134 EXPORT_SYMBOL(fiemap_fill_next_extent);
 135
 136 /**
 137  * fiemap_check_flags - check validity of requested flags for fiemap
 138  * @fieinfo:    Fiemap context passed into ->fiemap
 139  * @fs_flags:   Set of fiemap flags that the file system understands
 140  *
 141  * Called from file system ->fiemap callback. This will compute the
 142  * intersection of valid fiemap flags and those that the fs supports. That
 143  * value is then compared against the user supplied flags. In case of bad user
 144  * flags, the invalid values will be written into the fieinfo structure, and
 145  * -EBADR is returned, which tells ioctl_fiemap() to return those values to
 146  * userspace. For this reason, a return code of -EBADR should be preserved.
 147  *
 148  * Returns 0 on success, -EBADR on bad flags.
 149  */
 150 int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags)
 151 {
 152         u32 incompat_flags;
 153
 154         incompat_flags = fieinfo->fi_flags & ~(FIEMAP_FLAGS_COMPAT & fs_flags);
 155         if (incompat_flags) {
 156                 fieinfo->fi_flags = incompat_flags;
 157                 return -EBADR;
 158         }
 159         return 0;
 160 }
 161 EXPORT_SYMBOL(fiemap_check_flags);
 162
 163 static int fiemap_check_ranges(struct super_block *sb,
 164                                u64 start, u64 len, u64 *new_len)
 165 {
 166         *new_len = len;
 167
 168         if (len == 0)
 169                 return -EINVAL;
 170
 171         if (start > sb->s_maxbytes)
 172                 return -EFBIG;
 173
 174         /*
 175          * Shrink request scope to what the fs can actually handle.
 176          */
 177         if ((len > sb->s_maxbytes) ||
 178             (sb->s_maxbytes - len) < start)
 179                 *new_len = sb->s_maxbytes - start;
 180
 181         return 0;
 182 }
 183
 184 static int ioctl_fiemap(struct file *filp, unsigned long arg)
 185 {
 186         struct fiemap fiemap;
 187         struct fiemap_extent_info fieinfo = { 0, };
 188         struct inode *inode = filp->f_path.dentry->d_inode;
 189         struct super_block *sb = inode->i_sb;
 190         u64 len;
 191         int error;
 192
 193         if (!inode->i_op->fiemap)
 194                 return -EOPNOTSUPP;
 195
 196         if (copy_from_user(&fiemap, (struct fiemap __user *)arg,
 197                            sizeof(struct fiemap)))
 198                 return -EFAULT;
 199
 200         if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
 201                 return -EINVAL;
 202
 203         error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
 204                                     &len);
 205         if (error)
 206                 return error;
 207
 208         fieinfo.fi_flags = fiemap.fm_flags;
 209         fieinfo.fi_extents_max = fiemap.fm_extent_count;
 210         fieinfo.fi_extents_start = (struct fiemap_extent *)(arg + sizeof(fiemap));
 211
 212         if (fiemap.fm_extent_count != 0 &&
 213             !access_ok(VERIFY_WRITE, fieinfo.fi_extents_start,
 214                        fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
 215                 return -EFAULT;
 216
 217         if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
 218                 filemap_write_and_wait(inode->i_mapping);
 219
 220         error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start, len);
 221         fiemap.fm_flags = fieinfo.fi_flags;
 222         fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
 223         if (copy_to_user((char *)arg, &fiemap, sizeof(fiemap)))
 224                 error = -EFAULT;
 225
 226         return error;
 227 }
 228
 229 #ifdef CONFIG_BLOCK
 230
 231 #define blk_to_logical(inode, blk) (blk << (inode)->i_blkbits)
 232 #define logical_to_blk(inode, offset) (offset >> (inode)->i_blkbits);
 233
 234 /**
 235  * __generic_block_fiemap - FIEMAP for block based inodes (no locking)
 236  * @inode - the inode to map
 237  * @arg - the pointer to userspace where we copy everything to
 238  * @get_block - the fs's get_block function
 239  *
 240  * This does FIEMAP for block based inodes.  Basically it will just loop
 241  * through get_block until we hit the number of extents we want to map, or we
 242  * go past the end of the file and hit a hole.
 243  *
 244  * If it is possible to have data blocks beyond a hole past @inode->i_size, then
 245  * please do not use this function, it will stop at the first unmapped block
 246  * beyond i_size.
 247  *
 248  * If you use this function directly, you need to do your own locking. Use
 249  * generic_block_fiemap if you want the locking done for you.
 250  */
 251
 252 int __generic_block_fiemap(struct inode *inode,
 253                            struct fiemap_extent_info *fieinfo, u64 start,
 254                            u64 len, get_block_t *get_block)
 255 {
 256         struct buffer_head tmp;
 257         unsigned int start_blk;
 258         long long length = 0, map_len = 0;
 259         u64 logical = 0, phys = 0, size = 0;
 260         u32 flags = FIEMAP_EXTENT_MERGED;
 261         int ret = 0;
 262
 263         if ((ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC)))
 264                 return ret;
 265
 266         start_blk = logical_to_blk(inode, start);
 267
 268         length = (long long)min_t(u64, len, i_size_read(inode));
 269         map_len = length;
 270
 271         do {
 272                 /*
 273                  * we set b_size to the total size we want so it will map as
 274                  * many contiguous blocks as possible at once
 275                  */
 276                 memset(&tmp, 0, sizeof(struct buffer_head));
 277                 tmp.b_size = map_len;
 278
 279                 ret = get_block(inode, start_blk, &tmp, 0);
 280                 if (ret)
 281                         break;
 282
 283                 /* HOLE */
 284                 if (!buffer_mapped(&tmp)) {
 285                         /*
 286                          * first hole after going past the EOF, this is our
 287                          * last extent
 288                          */
 289                         if (length <= 0) {
 290                                 flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
 291                                 ret = fiemap_fill_next_extent(fieinfo, logical,
 292                                                               phys, size,
 293                                                               flags);
 294                                 break;
 295                         }
 296
 297                         length -= blk_to_logical(inode, 1);
 298
 299                         /* if we have holes up to/past EOF then we're done */
 300                         if (length <= 0)
 301                                 break;
 302
 303                         start_blk++;
 304                 } else {
 305                         if (length <= 0 && size) {
 306                                 ret = fiemap_fill_next_extent(fieinfo, logical,
 307                                                               phys, size,
 308                                                               flags);
 309                                 if (ret)
 310                                         break;
 311                         }
 312
 313                         logical = blk_to_logical(inode, start_blk);
 314                         phys = blk_to_logical(inode, tmp.b_blocknr);
 315                         size = tmp.b_size;
 316                         flags = FIEMAP_EXTENT_MERGED;
 317
 318                         length -= tmp.b_size;
 319                         start_blk += logical_to_blk(inode, size);
 320
 321                         /*
 322                          * if we are past the EOF we need to loop again to see
 323                          * if there is a hole so we can mark this extent as the
 324                          * last one, and if not keep mapping things until we
 325                          * find a hole, or we run out of slots in the extent
 326                          * array
 327                          */
 328                         if (length <= 0)
 329                                 continue;
 330
 331                         ret = fiemap_fill_next_extent(fieinfo, logical, phys,
 332                                                       size, flags);
 333                         if (ret)
 334                                 break;
 335                 }
 336                 cond_resched();
 337         } while (1);
 338
 339         /* if ret is 1 then we just hit the end of the extent array */
 340         if (ret == 1)
 341                 ret = 0;
 342
 343         return ret;
 344 }
 345 EXPORT_SYMBOL(__generic_block_fiemap);
 346
 347 /**
 348  * generic_block_fiemap - FIEMAP for block based inodes
 349  * @inode: The inode to map
 350  * @fieinfo: The mapping information
 351  * @start: The initial block to map
 352  * @len: The length of the extect to attempt to map
 353  * @get_block: The block mapping function for the fs
 354  *
 355  * Calls __generic_block_fiemap to map the inode, after taking
 356  * the inode's mutex lock.
 357  */
 358
 359 int generic_block_fiemap(struct inode *inode,
 360                          struct fiemap_extent_info *fieinfo, u64 start,
 361                          u64 len, get_block_t *get_block)
 362 {
 363         int ret;
 364         mutex_lock(&inode->i_mutex);
 365         ret = __generic_block_fiemap(inode, fieinfo, start, len, get_block);
 366         mutex_unlock(&inode->i_mutex);
 367         return ret;
 368 }
 369 EXPORT_SYMBOL(generic_block_fiemap);
 370
 371 #endif  /*  CONFIG_BLOCK  */
 372
 373 static int file_ioctl(struct file *filp, unsigned int cmd,
 374                 unsigned long arg)
 375 {
 376         struct inode *inode = filp->f_path.dentry->d_inode;
 377         int __user *p = (int __user *)arg;
 378
 379         switch (cmd) {
 380         case FIBMAP:
 381                 return ioctl_fibmap(filp, p);
 382         case FS_IOC_FIEMAP:
 383                 return ioctl_fiemap(filp, arg);
 384         case FIGETBSZ:
 385                 return put_user(inode->i_sb->s_blocksize, p);
 386         case FIONREAD:
 387                 return put_user(i_size_read(inode) - filp->f_pos, p);
 388         }
 389
 390         return vfs_ioctl(filp, cmd, arg);
 391 }
 392
 393 static int ioctl_fionbio(struct file *filp, int __user *argp)
 394 {
 395         unsigned int flag;
 396         int on, error;
 397
 398         error = get_user(on, argp);
 399         if (error)
 400                 return error;
 401         flag = O_NONBLOCK;
 402 #ifdef __sparc__
 403         /* SunOS compatibility item. */
 404         if (O_NONBLOCK != O_NDELAY)
 405                 flag |= O_NDELAY;
 406 #endif
 407         if (on)
 408                 filp->f_flags |= flag;
 409         else
 410                 filp->f_flags &= ~flag;
 411         return error;
 412 }
 413
 414 static int ioctl_fioasync(unsigned int fd, struct file *filp,
 415                           int __user *argp)
 416 {
 417         unsigned int flag;
 418         int on, error;
 419
 420         error = get_user(on, argp);
 421         if (error)
 422                 return error;
 423         flag = on ? FASYNC : 0;
 424
 425         /* Did FASYNC state change ? */
 426         if ((flag ^ filp->f_flags) & FASYNC) {
 427                 if (filp->f_op && filp->f_op->fasync)
 428                         error = filp->f_op->fasync(fd, filp, on);
 429                 else
 430                         error = -ENOTTY;
 431         }
 432         if (error)
 433                 return error;
 434
 435         if (on)
 436                 filp->f_flags |= FASYNC;
 437         else
 438                 filp->f_flags &= ~FASYNC;
 439         return error;
 440 }
 441
 442 static int ioctl_fsfreeze(struct file *filp)
 443 {
 444         struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
 445
 446         if (!capable(CAP_SYS_ADMIN))
 447                 return -EPERM;
 448
 449         /* If filesystem doesn't support freeze feature, return. */
 450         if (sb->s_op->freeze_fs == NULL)
 451                 return -EOPNOTSUPP;
 452
 453         /* If a blockdevice-backed filesystem isn't specified, return. */
 454         if (sb->s_bdev == NULL)
 455                 return -EINVAL;
 456
 457         /* Freeze */
 458         sb = freeze_bdev(sb->s_bdev);
 459         if (IS_ERR(sb))
 460                 return PTR_ERR(sb);
 461         return 0;
 462 }
 463
 464 static int ioctl_fsthaw(struct file *filp)
 465 {
 466         struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
 467
 468         if (!capable(CAP_SYS_ADMIN))
 469                 return -EPERM;
 470
 471         /* If a blockdevice-backed filesystem isn't specified, return EINVAL. */
 472         if (sb->s_bdev == NULL)
 473                 return -EINVAL;
 474
 475         /* Thaw */
 476         return thaw_bdev(sb->s_bdev, sb);
 477 }
 478
 479 /*
 480  * When you add any new common ioctls to the switches above and below
 481  * please update compat_sys_ioctl() too.
 482  *
 483  * do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d.
 484  * It's just a simple helper for sys_ioctl and compat_sys_ioctl.
 485  */
 486 int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
 487              unsigned long arg)
 488 {
 489         int error = 0;
 490         int __user *argp = (int __user *)arg;
 491
 492         switch (cmd) {
 493         case FIOCLEX:
 494                 set_close_on_exec(fd, 1);
 495                 break;
 496
 497         case FIONCLEX:
 498                 set_close_on_exec(fd, 0);
 499                 break;
 500
 501         case FIONBIO:
 502                 /* BKL needed to avoid races tweaking f_flags */
 503                 lock_kernel();
 504                 error = ioctl_fionbio(filp, argp);
 505                 unlock_kernel();
 506                 break;
 507
 508         case FIOASYNC:
 509                 /* BKL needed to avoid races tweaking f_flags */
 510                 lock_kernel();
 511                 error = ioctl_fioasync(fd, filp, argp);
 512                 unlock_kernel();
 513                 break;
 514
 515         case FIOQSIZE:
 516                 if (S_ISDIR(filp->f_path.dentry->d_inode->i_mode) ||
 517                     S_ISREG(filp->f_path.dentry->d_inode->i_mode) ||
 518                     S_ISLNK(filp->f_path.dentry->d_inode->i_mode)) {
 519                         loff_t res =
 520                                 inode_get_bytes(filp->f_path.dentry->d_inode);
 521                         error = copy_to_user((loff_t __user *)arg, &res,
 522                                              sizeof(res)) ? -EFAULT : 0;
 523                 } else
 524                         error = -ENOTTY;
 525                 break;
 526
 527         case FIFREEZE:
 528                 error = ioctl_fsfreeze(filp);
 529                 break;
 530
 531         case FITHAW:
 532                 error = ioctl_fsthaw(filp);
 533                 break;
 534
 535         default:
 536                 if (S_ISREG(filp->f_path.dentry->d_inode->i_mode))
 537                         error = file_ioctl(filp, cmd, arg);
 538                 else
 539                         error = vfs_ioctl(filp, cmd, arg);
 540                 break;
 541         }
 542         return error;
 543 }
 544
 545 SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 546 {
 547         struct file *filp;
 548         int error = -EBADF;
 549         int fput_needed;
 550
 551         filp = fget_light(fd, &fput_needed);
 552         if (!filp)
 553                 goto out;
 554
 555         error = security_file_ioctl(filp, cmd, arg);
 556         if (error)
 557                 goto out_fput;
 558
 559         error = do_vfs_ioctl(filp, fd, cmd, arg);
 560  out_fput:
 561         fput_light(filp, fput_needed);
 562  out:
 563         return error;
 564 }