linux/fs/ioctl.c
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   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/export.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 */
  35static 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 = -ENOTTY;
  46 out:
  47        return error;
  48}
  49
  50static 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)
  85int 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 __user *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}
 122EXPORT_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 */
 138int 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}
 149EXPORT_SYMBOL(fiemap_check_flags);
 150
 151static 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
 173static int ioctl_fiemap(struct file *filp, unsigned long arg)
 174{
 175        struct fiemap fiemap;
 176        struct fiemap __user *ufiemap = (struct fiemap __user *) arg;
 177        struct fiemap_extent_info fieinfo = { 0, };
 178        struct inode *inode = filp->f_path.dentry->d_inode;
 179        struct super_block *sb = inode->i_sb;
 180        u64 len;
 181        int error;
 182
 183        if (!inode->i_op->fiemap)
 184                return -EOPNOTSUPP;
 185
 186        if (copy_from_user(&fiemap, ufiemap, sizeof(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 = ufiemap->fm_extents;
 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(ufiemap, &fiemap, sizeof(fiemap)))
 213                error = -EFAULT;
 214
 215        return error;
 216}
 217
 218#ifdef CONFIG_BLOCK
 219
 220static inline sector_t logical_to_blk(struct inode *inode, loff_t offset)
 221{
 222        return (offset >> inode->i_blkbits);
 223}
 224
 225static 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
 250int __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        /*
 277         * Some filesystems can't deal with being asked to map less than
 278         * blocksize, so make sure our len is at least block length.
 279         */
 280        if (logical_to_blk(inode, len) == 0)
 281                len = blk_to_logical(inode, 1);
 282
 283        start_blk = logical_to_blk(inode, start);
 284        last_blk = logical_to_blk(inode, start + len - 1);
 285
 286        do {
 287                /*
 288                 * we set b_size to the total size we want so it will map as
 289                 * many contiguous blocks as possible at once
 290                 */
 291                memset(&map_bh, 0, sizeof(struct buffer_head));
 292                map_bh.b_size = len;
 293
 294                ret = get_block(inode, start_blk, &map_bh, 0);
 295                if (ret)
 296                        break;
 297
 298                /* HOLE */
 299                if (!buffer_mapped(&map_bh)) {
 300                        start_blk++;
 301
 302                        /*
 303                         * We want to handle the case where there is an
 304                         * allocated block at the front of the file, and then
 305                         * nothing but holes up to the end of the file properly,
 306                         * to make sure that extent at the front gets properly
 307                         * marked with FIEMAP_EXTENT_LAST
 308                         */
 309                        if (!past_eof &&
 310                            blk_to_logical(inode, start_blk) >= isize)
 311                                past_eof = 1;
 312
 313                        /*
 314                         * First hole after going past the EOF, this is our
 315                         * last extent
 316                         */
 317                        if (past_eof && size) {
 318                                flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
 319                                ret = fiemap_fill_next_extent(fieinfo, logical,
 320                                                              phys, size,
 321                                                              flags);
 322                        } else if (size) {
 323                                ret = fiemap_fill_next_extent(fieinfo, logical,
 324                                                              phys, size, flags);
 325                                size = 0;
 326                        }
 327
 328                        /* if we have holes up to/past EOF then we're done */
 329                        if (start_blk > last_blk || past_eof || ret)
 330                                break;
 331                } else {
 332                        /*
 333                         * We have gone over the length of what we wanted to
 334                         * map, and it wasn't the entire file, so add the extent
 335                         * we got last time and exit.
 336                         *
 337                         * This is for the case where say we want to map all the
 338                         * way up to the second to the last block in a file, but
 339                         * the last block is a hole, making the second to last
 340                         * block FIEMAP_EXTENT_LAST.  In this case we want to
 341                         * see if there is a hole after the second to last block
 342                         * so we can mark it properly.  If we found data after
 343                         * we exceeded the length we were requesting, then we
 344                         * are good to go, just add the extent to the fieinfo
 345                         * and break
 346                         */
 347                        if (start_blk > last_blk && !whole_file) {
 348                                ret = fiemap_fill_next_extent(fieinfo, logical,
 349                                                              phys, size,
 350                                                              flags);
 351                                break;
 352                        }
 353
 354                        /*
 355                         * if size != 0 then we know we already have an extent
 356                         * to add, so add it.
 357                         */
 358                        if (size) {
 359                                ret = fiemap_fill_next_extent(fieinfo, logical,
 360                                                              phys, size,
 361                                                              flags);
 362                                if (ret)
 363                                        break;
 364                        }
 365
 366                        logical = blk_to_logical(inode, start_blk);
 367                        phys = blk_to_logical(inode, map_bh.b_blocknr);
 368                        size = map_bh.b_size;
 369                        flags = FIEMAP_EXTENT_MERGED;
 370
 371                        start_blk += logical_to_blk(inode, size);
 372
 373                        /*
 374                         * If we are past the EOF, then we need to make sure as
 375                         * soon as we find a hole that the last extent we found
 376                         * is marked with FIEMAP_EXTENT_LAST
 377                         */
 378                        if (!past_eof && logical + size >= isize)
 379                                past_eof = true;
 380                }
 381                cond_resched();
 382        } while (1);
 383
 384        /* If ret is 1 then we just hit the end of the extent array */
 385        if (ret == 1)
 386                ret = 0;
 387
 388        return ret;
 389}
 390EXPORT_SYMBOL(__generic_block_fiemap);
 391
 392/**
 393 * generic_block_fiemap - FIEMAP for block based inodes
 394 * @inode: The inode to map
 395 * @fieinfo: The mapping information
 396 * @start: The initial block to map
 397 * @len: The length of the extect to attempt to map
 398 * @get_block: The block mapping function for the fs
 399 *
 400 * Calls __generic_block_fiemap to map the inode, after taking
 401 * the inode's mutex lock.
 402 */
 403
 404int generic_block_fiemap(struct inode *inode,
 405                         struct fiemap_extent_info *fieinfo, u64 start,
 406                         u64 len, get_block_t *get_block)
 407{
 408        int ret;
 409        mutex_lock(&inode->i_mutex);
 410        ret = __generic_block_fiemap(inode, fieinfo, start, len, get_block);
 411        mutex_unlock(&inode->i_mutex);
 412        return ret;
 413}
 414EXPORT_SYMBOL(generic_block_fiemap);
 415
 416#endif  /*  CONFIG_BLOCK  */
 417
 418/*
 419 * This provides compatibility with legacy XFS pre-allocation ioctls
 420 * which predate the fallocate syscall.
 421 *
 422 * Only the l_start, l_len and l_whence fields of the 'struct space_resv'
 423 * are used here, rest are ignored.
 424 */
 425int ioctl_preallocate(struct file *filp, void __user *argp)
 426{
 427        struct inode *inode = filp->f_path.dentry->d_inode;
 428        struct space_resv sr;
 429
 430        if (copy_from_user(&sr, argp, sizeof(sr)))
 431                return -EFAULT;
 432
 433        switch (sr.l_whence) {
 434        case SEEK_SET:
 435                break;
 436        case SEEK_CUR:
 437                sr.l_start += filp->f_pos;
 438                break;
 439        case SEEK_END:
 440                sr.l_start += i_size_read(inode);
 441                break;
 442        default:
 443                return -EINVAL;
 444        }
 445
 446        return do_fallocate(filp, FALLOC_FL_KEEP_SIZE, sr.l_start, sr.l_len);
 447}
 448
 449static int file_ioctl(struct file *filp, unsigned int cmd,
 450                unsigned long arg)
 451{
 452        struct inode *inode = filp->f_path.dentry->d_inode;
 453        int __user *p = (int __user *)arg;
 454
 455        switch (cmd) {
 456        case FIBMAP:
 457                return ioctl_fibmap(filp, p);
 458        case FIONREAD:
 459                return put_user(i_size_read(inode) - filp->f_pos, p);
 460        case FS_IOC_RESVSP:
 461        case FS_IOC_RESVSP64:
 462                return ioctl_preallocate(filp, p);
 463        }
 464
 465        return vfs_ioctl(filp, cmd, arg);
 466}
 467
 468static int ioctl_fionbio(struct file *filp, int __user *argp)
 469{
 470        unsigned int flag;
 471        int on, error;
 472
 473        error = get_user(on, argp);
 474        if (error)
 475                return error;
 476        flag = O_NONBLOCK;
 477#ifdef __sparc__
 478        /* SunOS compatibility item. */
 479        if (O_NONBLOCK != O_NDELAY)
 480                flag |= O_NDELAY;
 481#endif
 482        spin_lock(&filp->f_lock);
 483        if (on)
 484                filp->f_flags |= flag;
 485        else
 486                filp->f_flags &= ~flag;
 487        spin_unlock(&filp->f_lock);
 488        return error;
 489}
 490
 491static int ioctl_fioasync(unsigned int fd, struct file *filp,
 492                          int __user *argp)
 493{
 494        unsigned int flag;
 495        int on, error;
 496
 497        error = get_user(on, argp);
 498        if (error)
 499                return error;
 500        flag = on ? FASYNC : 0;
 501
 502        /* Did FASYNC state change ? */
 503        if ((flag ^ filp->f_flags) & FASYNC) {
 504                if (filp->f_op && filp->f_op->fasync)
 505                        /* fasync() adjusts filp->f_flags */
 506                        error = filp->f_op->fasync(fd, filp, on);
 507                else
 508                        error = -ENOTTY;
 509        }
 510        return error < 0 ? error : 0;
 511}
 512
 513static int ioctl_fsfreeze(struct file *filp)
 514{
 515        struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
 516
 517        if (!capable(CAP_SYS_ADMIN))
 518                return -EPERM;
 519
 520        /* If filesystem doesn't support freeze feature, return. */
 521        if (sb->s_op->freeze_fs == NULL)
 522                return -EOPNOTSUPP;
 523
 524        /* Freeze */
 525        return freeze_super(sb);
 526}
 527
 528static int ioctl_fsthaw(struct file *filp)
 529{
 530        struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
 531
 532        if (!capable(CAP_SYS_ADMIN))
 533                return -EPERM;
 534
 535        /* Thaw */
 536        return thaw_super(sb);
 537}
 538
 539/*
 540 * When you add any new common ioctls to the switches above and below
 541 * please update compat_sys_ioctl() too.
 542 *
 543 * do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d.
 544 * It's just a simple helper for sys_ioctl and compat_sys_ioctl.
 545 */
 546int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
 547             unsigned long arg)
 548{
 549        int error = 0;
 550        int __user *argp = (int __user *)arg;
 551        struct inode *inode = filp->f_path.dentry->d_inode;
 552
 553        switch (cmd) {
 554        case FIOCLEX:
 555                set_close_on_exec(fd, 1);
 556                break;
 557
 558        case FIONCLEX:
 559                set_close_on_exec(fd, 0);
 560                break;
 561
 562        case FIONBIO:
 563                error = ioctl_fionbio(filp, argp);
 564                break;
 565
 566        case FIOASYNC:
 567                error = ioctl_fioasync(fd, filp, argp);
 568                break;
 569
 570        case FIOQSIZE:
 571                if (S_ISDIR(inode->i_mode) || S_ISREG(inode->i_mode) ||
 572                    S_ISLNK(inode->i_mode)) {
 573                        loff_t res = inode_get_bytes(inode);
 574                        error = copy_to_user(argp, &res, sizeof(res)) ?
 575                                        -EFAULT : 0;
 576                } else
 577                        error = -ENOTTY;
 578                break;
 579
 580        case FIFREEZE:
 581                error = ioctl_fsfreeze(filp);
 582                break;
 583
 584        case FITHAW:
 585                error = ioctl_fsthaw(filp);
 586                break;
 587
 588        case FS_IOC_FIEMAP:
 589                return ioctl_fiemap(filp, arg);
 590
 591        case FIGETBSZ:
 592                return put_user(inode->i_sb->s_blocksize, argp);
 593
 594        default:
 595                if (S_ISREG(inode->i_mode))
 596                        error = file_ioctl(filp, cmd, arg);
 597                else
 598                        error = vfs_ioctl(filp, cmd, arg);
 599                break;
 600        }
 601        return error;
 602}
 603
 604SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 605{
 606        int error;
 607        struct fd f = fdget(fd);
 608
 609        if (!f.file)
 610                return -EBADF;
 611        error = security_file_ioctl(f.file, cmd, arg);
 612        if (!error)
 613                error = do_vfs_ioctl(f.file, fd, cmd, arg);
 614        fdput(f);
 615        return error;
 616}
 617
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