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/capability.h>
  10 #include <linux/file.h>
  11 #include <linux/fs.h>
  12 #include <linux/security.h>
  13 #include <linux/module.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/writeback.h>
  16 #include <linux/buffer_head.h>
  17 #include <linux/falloc.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  * returns -ENOTTY.
  32  *
  33  * Returns 0 on success, -errno on error.
  34  */
  35 static long vfs_ioctl(struct file *filp, unsigned int cmd,
  36                       unsigned long arg)
  37 {
  38         int error = -ENOTTY;
  39
  40         if (!filp->f_op || !filp->f_op->unlocked_ioctl)
  41                 goto out;
  42
  43         error = filp->f_op->unlocked_ioctl(filp, cmd, arg);
  44         if (error == -ENOIOCTLCMD)
  45                 error = -EINVAL;
  46  out:
  47         return error;
  48 }
  49
  50 static int ioctl_fibmap(struct file *filp, int __user *p)
  51 {
  52         struct address_space *mapping = filp->f_mapping;
  53         int res, block;
  54
  55         /* do we support this mess? */
  56         if (!mapping->a_ops->bmap)
  57                 return -EINVAL;
  58         if (!capable(CAP_SYS_RAWIO))
  59                 return -EPERM;
  60         res = get_user(block, p);
  61         if (res)
  62                 return res;
  63         res = mapping->a_ops->bmap(mapping, block);
  64         return put_user(res, p);
  65 }
  66
  67 /**
  68  * fiemap_fill_next_extent - Fiemap helper function
  69  * @fieinfo:    Fiemap context passed into ->fiemap
  70  * @logical:    Extent logical start offset, in bytes
  71  * @phys:       Extent physical start offset, in bytes
  72  * @len:        Extent length, in bytes
  73  * @flags:      FIEMAP_EXTENT flags that describe this extent
  74  *
  75  * Called from file system ->fiemap callback. Will populate extent
  76  * info as passed in via arguments and copy to user memory. On
  77  * success, extent count on fieinfo is incremented.
  78  *
  79  * Returns 0 on success, -errno on error, 1 if this was the last
  80  * extent that will fit in user array.
  81  */
  82 #define SET_UNKNOWN_FLAGS       (FIEMAP_EXTENT_DELALLOC)
  83 #define SET_NO_UNMOUNTED_IO_FLAGS       (FIEMAP_EXTENT_DATA_ENCRYPTED)
  84 #define SET_NOT_ALIGNED_FLAGS   (FIEMAP_EXTENT_DATA_TAIL|FIEMAP_EXTENT_DATA_INLINE)
  85 int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
  86                             u64 phys, u64 len, u32 flags)
  87 {
  88         struct fiemap_extent extent;
  89         struct fiemap_extent *dest = fieinfo->fi_extents_start;
  90
  91         /* only count the extents */
  92         if (fieinfo->fi_extents_max == 0) {
  93                 fieinfo->fi_extents_mapped++;
  94                 return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
  95         }
  96
  97         if (fieinfo->fi_extents_mapped >= fieinfo->fi_extents_max)
  98                 return 1;
  99
 100         if (flags & SET_UNKNOWN_FLAGS)
 101                 flags |= FIEMAP_EXTENT_UNKNOWN;
 102         if (flags & SET_NO_UNMOUNTED_IO_FLAGS)
 103                 flags |= FIEMAP_EXTENT_ENCODED;
 104         if (flags & SET_NOT_ALIGNED_FLAGS)
 105                 flags |= FIEMAP_EXTENT_NOT_ALIGNED;
 106
 107         memset(&extent, 0, sizeof(extent));
 108         extent.fe_logical = logical;
 109         extent.fe_physical = phys;
 110         extent.fe_length = len;
 111         extent.fe_flags = flags;
 112
 113         dest += fieinfo->fi_extents_mapped;
 114         if (copy_to_user(dest, &extent, sizeof(extent)))
 115                 return -EFAULT;
 116
 117         fieinfo->fi_extents_mapped++;
 118         if (fieinfo->fi_extents_mapped == fieinfo->fi_extents_max)
 119                 return 1;
 120         return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
 121 }
 122 EXPORT_SYMBOL(fiemap_fill_next_extent);
 123
 124 /**
 125  * fiemap_check_flags - check validity of requested flags for fiemap
 126  * @fieinfo:    Fiemap context passed into ->fiemap
 127  * @fs_flags:   Set of fiemap flags that the file system understands
 128  *
 129  * Called from file system ->fiemap callback. This will compute the
 130  * intersection of valid fiemap flags and those that the fs supports. That
 131  * value is then compared against the user supplied flags. In case of bad user
 132  * flags, the invalid values will be written into the fieinfo structure, and
 133  * -EBADR is returned, which tells ioctl_fiemap() to return those values to
 134  * userspace. For this reason, a return code of -EBADR should be preserved.
 135  *
 136  * Returns 0 on success, -EBADR on bad flags.
 137  */
 138 int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags)
 139 {
 140         u32 incompat_flags;
 141
 142         incompat_flags = fieinfo->fi_flags & ~(FIEMAP_FLAGS_COMPAT & fs_flags);
 143         if (incompat_flags) {
 144                 fieinfo->fi_flags = incompat_flags;
 145                 return -EBADR;
 146         }
 147         return 0;
 148 }
 149 EXPORT_SYMBOL(fiemap_check_flags);
 150
 151 static int fiemap_check_ranges(struct super_block *sb,
 152                                u64 start, u64 len, u64 *new_len)
 153 {
 154         u64 maxbytes = (u64) sb->s_maxbytes;
 155
 156         *new_len = len;
 157
 158         if (len == 0)
 159                 return -EINVAL;
 160
 161         if (start > maxbytes)
 162                 return -EFBIG;
 163
 164         /*
 165          * Shrink request scope to what the fs can actually handle.
 166          */
 167         if (len > maxbytes || (maxbytes - len) < start)
 168                 *new_len = maxbytes - start;
 169
 170         return 0;
 171 }
 172
 173 static int ioctl_fiemap(struct file *filp, unsigned long arg)
 174 {
 175         struct fiemap fiemap;
 176         struct fiemap_extent_info fieinfo = { 0, };
 177         struct inode *inode = filp->f_path.dentry->d_inode;
 178         struct super_block *sb = inode->i_sb;
 179         u64 len;
 180         int error;
 181
 182         if (!inode->i_op->fiemap)
 183                 return -EOPNOTSUPP;
 184
 185         if (copy_from_user(&fiemap, (struct fiemap __user *)arg,
 186                            sizeof(struct fiemap)))
 187                 return -EFAULT;
 188
 189         if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
 190                 return -EINVAL;
 191
 192         error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
 193                                     &len);
 194         if (error)
 195                 return error;
 196
 197         fieinfo.fi_flags = fiemap.fm_flags;
 198         fieinfo.fi_extents_max = fiemap.fm_extent_count;
 199         fieinfo.fi_extents_start = (struct fiemap_extent *)(arg + sizeof(fiemap));
 200
 201         if (fiemap.fm_extent_count != 0 &&
 202             !access_ok(VERIFY_WRITE, fieinfo.fi_extents_start,
 203                        fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
 204                 return -EFAULT;
 205
 206         if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
 207                 filemap_write_and_wait(inode->i_mapping);
 208
 209         error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start, len);
 210         fiemap.fm_flags = fieinfo.fi_flags;
 211         fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
 212         if (copy_to_user((char *)arg, &fiemap, sizeof(fiemap)))
 213                 error = -EFAULT;
 214
 215         return error;
 216 }
 217
 218 #ifdef CONFIG_BLOCK
 219
 220 static inline sector_t logical_to_blk(struct inode *inode, loff_t offset)
 221 {
 222         return (offset >> inode->i_blkbits);
 223 }
 224
 225 static inline loff_t blk_to_logical(struct inode *inode, sector_t blk)
 226 {
 227         return (blk << inode->i_blkbits);
 228 }
 229
 230 /**
 231  * __generic_block_fiemap - FIEMAP for block based inodes (no locking)
 232  * @inode: the inode to map
 233  * @fieinfo: the fiemap info struct that will be passed back to userspace
 234  * @start: where to start mapping in the inode
 235  * @len: how much space to map
 236  * @get_block: the fs's get_block function
 237  *
 238  * This does FIEMAP for block based inodes.  Basically it will just loop
 239  * through get_block until we hit the number of extents we want to map, or we
 240  * go past the end of the file and hit a hole.
 241  *
 242  * If it is possible to have data blocks beyond a hole past @inode->i_size, then
 243  * please do not use this function, it will stop at the first unmapped block
 244  * beyond i_size.
 245  *
 246  * If you use this function directly, you need to do your own locking. Use
 247  * generic_block_fiemap if you want the locking done for you.
 248  */
 249
 250 int __generic_block_fiemap(struct inode *inode,
 251                            struct fiemap_extent_info *fieinfo, loff_t start,
 252                            loff_t len, get_block_t *get_block)
 253 {
 254         struct buffer_head map_bh;
 255         sector_t start_blk, last_blk;
 256         loff_t isize = i_size_read(inode);
 257         u64 logical = 0, phys = 0, size = 0;
 258         u32 flags = FIEMAP_EXTENT_MERGED;
 259         bool past_eof = false, whole_file = false;
 260         int ret = 0;
 261
 262         ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
 263         if (ret)
 264                 return ret;
 265
 266         /*
 267          * Either the i_mutex or other appropriate locking needs to be held
 268          * since we expect isize to not change at all through the duration of
 269          * this call.
 270          */
 271         if (len >= isize) {
 272                 whole_file = true;
 273                 len = isize;
 274         }
 275
 276         start_blk = logical_to_blk(inode, start);
 277         last_blk = logical_to_blk(inode, start + len - 1);
 278
 279         do {
 280                 /*
 281                  * we set b_size to the total size we want so it will map as
 282                  * many contiguous blocks as possible at once
 283                  */
 284                 memset(&map_bh, 0, sizeof(struct buffer_head));
 285                 map_bh.b_size = len;
 286
 287                 ret = get_block(inode, start_blk, &map_bh, 0);
 288                 if (ret)
 289                         break;
 290
 291                 /* HOLE */
 292                 if (!buffer_mapped(&map_bh)) {
 293                         start_blk++;
 294
 295                         /*
 296                          * We want to handle the case where there is an
 297                          * allocated block at the front of the file, and then
 298                          * nothing but holes up to the end of the file properly,
 299                          * to make sure that extent at the front gets properly
 300                          * marked with FIEMAP_EXTENT_LAST
 301                          */
 302                         if (!past_eof &&
 303                             blk_to_logical(inode, start_blk) >= isize)
 304                                 past_eof = 1;
 305
 306                         /*
 307                          * First hole after going past the EOF, this is our
 308                          * last extent
 309                          */
 310                         if (past_eof && size) {
 311                                 flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
 312                                 ret = fiemap_fill_next_extent(fieinfo, logical,
 313                                                               phys, size,
 314                                                               flags);
 315                         } else if (size) {
 316                                 ret = fiemap_fill_next_extent(fieinfo, logical,
 317                                                               phys, size, flags);
 318                                 size = 0;
 319                         }
 320
 321                         /* if we have holes up to/past EOF then we're done */
 322                         if (start_blk > last_blk || past_eof || ret)
 323                                 break;
 324                 } else {
 325                         /*
 326                          * We have gone over the length of what we wanted to
 327                          * map, and it wasn't the entire file, so add the extent
 328                          * we got last time and exit.
 329                          *
 330                          * This is for the case where say we want to map all the
 331                          * way up to the second to the last block in a file, but
 332                          * the last block is a hole, making the second to last
 333                          * block FIEMAP_EXTENT_LAST.  In this case we want to
 334                          * see if there is a hole after the second to last block
 335                          * so we can mark it properly.  If we found data after
 336                          * we exceeded the length we were requesting, then we
 337                          * are good to go, just add the extent to the fieinfo
 338                          * and break
 339                          */
 340                         if (start_blk > last_blk && !whole_file) {
 341                                 ret = fiemap_fill_next_extent(fieinfo, logical,
 342                                                               phys, size,
 343                                                               flags);
 344                                 break;
 345                         }
 346
 347                         /*
 348                          * if size != 0 then we know we already have an extent
 349                          * to add, so add it.
 350                          */
 351                         if (size) {
 352                                 ret = fiemap_fill_next_extent(fieinfo, logical,
 353                                                               phys, size,
 354                                                               flags);
 355                                 if (ret)
 356                                         break;
 357                         }
 358
 359                         logical = blk_to_logical(inode, start_blk);
 360                         phys = blk_to_logical(inode, map_bh.b_blocknr);
 361                         size = map_bh.b_size;
 362                         flags = FIEMAP_EXTENT_MERGED;
 363
 364                         start_blk += logical_to_blk(inode, size);
 365
 366                         /*
 367                          * If we are past the EOF, then we need to make sure as
 368                          * soon as we find a hole that the last extent we found
 369                          * is marked with FIEMAP_EXTENT_LAST
 370                          */
 371                         if (!past_eof && logical + size >= isize)
 372                                 past_eof = true;
 373                 }
 374                 cond_resched();
 375         } while (1);
 376
 377         /* If ret is 1 then we just hit the end of the extent array */
 378         if (ret == 1)
 379                 ret = 0;
 380
 381         return ret;
 382 }
 383 EXPORT_SYMBOL(__generic_block_fiemap);
 384
 385 /**
 386  * generic_block_fiemap - FIEMAP for block based inodes
 387  * @inode: The inode to map
 388  * @fieinfo: The mapping information
 389  * @start: The initial block to map
 390  * @len: The length of the extect to attempt to map
 391  * @get_block: The block mapping function for the fs
 392  *
 393  * Calls __generic_block_fiemap to map the inode, after taking
 394  * the inode's mutex lock.
 395  */
 396
 397 int generic_block_fiemap(struct inode *inode,
 398                          struct fiemap_extent_info *fieinfo, u64 start,
 399                          u64 len, get_block_t *get_block)
 400 {
 401         int ret;
 402         mutex_lock(&inode->i_mutex);
 403         ret = __generic_block_fiemap(inode, fieinfo, start, len, get_block);
 404         mutex_unlock(&inode->i_mutex);
 405         return ret;
 406 }
 407 EXPORT_SYMBOL(generic_block_fiemap);
 408
 409 #endif  /*  CONFIG_BLOCK  */
 410
 411 /*
 412  * This provides compatibility with legacy XFS pre-allocation ioctls
 413  * which predate the fallocate syscall.
 414  *
 415  * Only the l_start, l_len and l_whence fields of the 'struct space_resv'
 416  * are used here, rest are ignored.
 417  */
 418 int ioctl_preallocate(struct file *filp, void __user *argp)
 419 {
 420         struct inode *inode = filp->f_path.dentry->d_inode;
 421         struct space_resv sr;
 422
 423         if (copy_from_user(&sr, argp, sizeof(sr)))
 424                 return -EFAULT;
 425
 426         switch (sr.l_whence) {
 427         case SEEK_SET:
 428                 break;
 429         case SEEK_CUR:
 430                 sr.l_start += filp->f_pos;
 431                 break;
 432         case SEEK_END:
 433                 sr.l_start += i_size_read(inode);
 434                 break;
 435         default:
 436                 return -EINVAL;
 437         }
 438
 439         return do_fallocate(filp, FALLOC_FL_KEEP_SIZE, sr.l_start, sr.l_len);
 440 }
 441
 442 static int file_ioctl(struct file *filp, unsigned int cmd,
 443                 unsigned long arg)
 444 {
 445         struct inode *inode = filp->f_path.dentry->d_inode;
 446         int __user *p = (int __user *)arg;
 447
 448         switch (cmd) {
 449         case FIBMAP:
 450                 return ioctl_fibmap(filp, p);
 451         case FIONREAD:
 452                 return put_user(i_size_read(inode) - filp->f_pos, p);
 453         case FS_IOC_RESVSP:
 454         case FS_IOC_RESVSP64:
 455                 return ioctl_preallocate(filp, p);
 456         }
 457
 458         return vfs_ioctl(filp, cmd, arg);
 459 }
 460
 461 static int ioctl_fionbio(struct file *filp, int __user *argp)
 462 {
 463         unsigned int flag;
 464         int on, error;
 465
 466         error = get_user(on, argp);
 467         if (error)
 468                 return error;
 469         flag = O_NONBLOCK;
 470 #ifdef __sparc__
 471         /* SunOS compatibility item. */
 472         if (O_NONBLOCK != O_NDELAY)
 473                 flag |= O_NDELAY;
 474 #endif
 475         spin_lock(&filp->f_lock);
 476         if (on)
 477                 filp->f_flags |= flag;
 478         else
 479                 filp->f_flags &= ~flag;
 480         spin_unlock(&filp->f_lock);
 481         return error;
 482 }
 483
 484 static int ioctl_fioasync(unsigned int fd, struct file *filp,
 485                           int __user *argp)
 486 {
 487         unsigned int flag;
 488         int on, error;
 489
 490         error = get_user(on, argp);
 491         if (error)
 492                 return error;
 493         flag = on ? FASYNC : 0;
 494
 495         /* Did FASYNC state change ? */
 496         if ((flag ^ filp->f_flags) & FASYNC) {
 497                 if (filp->f_op && filp->f_op->fasync)
 498                         /* fasync() adjusts filp->f_flags */
 499                         error = filp->f_op->fasync(fd, filp, on);
 500                 else
 501                         error = -ENOTTY;
 502         }
 503         return error < 0 ? error : 0;
 504 }
 505
 506 static int ioctl_fsfreeze(struct file *filp)
 507 {
 508         struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
 509
 510         if (!capable(CAP_SYS_ADMIN))
 511                 return -EPERM;
 512
 513         /* If filesystem doesn't support freeze feature, return. */
 514         if (sb->s_op->freeze_fs == NULL)
 515                 return -EOPNOTSUPP;
 516
 517         /* Freeze */
 518         return freeze_super(sb);
 519 }
 520
 521 static int ioctl_fsthaw(struct file *filp)
 522 {
 523         struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
 524
 525         if (!capable(CAP_SYS_ADMIN))
 526                 return -EPERM;
 527
 528         /* Thaw */
 529         return thaw_super(sb);
 530 }
 531
 532 /*
 533  * When you add any new common ioctls to the switches above and below
 534  * please update compat_sys_ioctl() too.
 535  *
 536  * do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d.
 537  * It's just a simple helper for sys_ioctl and compat_sys_ioctl.
 538  */
 539 int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
 540              unsigned long arg)
 541 {
 542         int error = 0;
 543         int __user *argp = (int __user *)arg;
 544
 545         switch (cmd) {
 546         case FIOCLEX:
 547                 set_close_on_exec(fd, 1);
 548                 break;
 549
 550         case FIONCLEX:
 551                 set_close_on_exec(fd, 0);
 552                 break;
 553
 554         case FIONBIO:
 555                 error = ioctl_fionbio(filp, argp);
 556                 break;
 557
 558         case FIOASYNC:
 559                 error = ioctl_fioasync(fd, filp, argp);
 560                 break;
 561
 562         case FIOQSIZE:
 563                 if (S_ISDIR(filp->f_path.dentry->d_inode->i_mode) ||
 564                     S_ISREG(filp->f_path.dentry->d_inode->i_mode) ||
 565                     S_ISLNK(filp->f_path.dentry->d_inode->i_mode)) {
 566                         loff_t res =
 567                                 inode_get_bytes(filp->f_path.dentry->d_inode);
 568                         error = copy_to_user((loff_t __user *)arg, &res,
 569                                              sizeof(res)) ? -EFAULT : 0;
 570                 } else
 571                         error = -ENOTTY;
 572                 break;
 573
 574         case FIFREEZE:
 575                 error = ioctl_fsfreeze(filp);
 576                 break;
 577
 578         case FITHAW:
 579                 error = ioctl_fsthaw(filp);
 580                 break;
 581
 582         case FS_IOC_FIEMAP:
 583                 return ioctl_fiemap(filp, arg);
 584
 585         case FIGETBSZ:
 586         {
 587                 struct inode *inode = filp->f_path.dentry->d_inode;
 588                 int __user *p = (int __user *)arg;
 589                 return put_user(inode->i_sb->s_blocksize, p);
 590         }
 591
 592         default:
 593                 if (S_ISREG(filp->f_path.dentry->d_inode->i_mode))
 594                         error = file_ioctl(filp, cmd, arg);
 595                 else
 596                         error = vfs_ioctl(filp, cmd, arg);
 597                 break;
 598         }
 599         return error;
 600 }
 601
 602 SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 603 {
 604         struct file *filp;
 605         int error = -EBADF;
 606         int fput_needed;
 607
 608         filp = fget_light(fd, &fput_needed);
 609         if (!filp)
 610                 goto out;
 611
 612         error = security_file_ioctl(filp, cmd, arg);
 613         if (error)
 614                 goto out_fput;
 615
 616         error = do_vfs_ioctl(filp, fd, cmd, arg);
 617  out_fput:
 618         fput_light(filp, fput_needed);
 619  out:
 620         return error;
 621 }