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  * @inode - the inode to map
 236  * @arg - the pointer to userspace where we copy everything to
 237  * @get_block - the fs's get_block function
 238  *
 239  * This does FIEMAP for block based inodes.  Basically it will just loop
 240  * through get_block until we hit the number of extents we want to map, or we
 241  * go past the end of the file and hit a hole.
 242  *
 243  * If it is possible to have data blocks beyond a hole past @inode->i_size, then
 244  * please do not use this function, it will stop at the first unmapped block
 245  * beyond i_size
 246  */
 247 int generic_block_fiemap(struct inode *inode,
 248                          struct fiemap_extent_info *fieinfo, u64 start,
 249                          u64 len, get_block_t *get_block)
 250 {
 251         struct buffer_head tmp;
 252         unsigned int start_blk;
 253         long long length = 0, map_len = 0;
 254         u64 logical = 0, phys = 0, size = 0;
 255         u32 flags = FIEMAP_EXTENT_MERGED;
 256         int ret = 0;
 257
 258         if ((ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC)))
 259                 return ret;
 260
 261         start_blk = logical_to_blk(inode, start);
 262
 263         /* guard against change */
 264         mutex_lock(&inode->i_mutex);
 265
 266         length = (long long)min_t(u64, len, i_size_read(inode));
 267         map_len = length;
 268
 269         do {
 270                 /*
 271                  * we set b_size to the total size we want so it will map as
 272                  * many contiguous blocks as possible at once
 273                  */
 274                 memset(&tmp, 0, sizeof(struct buffer_head));
 275                 tmp.b_size = map_len;
 276
 277                 ret = get_block(inode, start_blk, &tmp, 0);
 278                 if (ret)
 279                         break;
 280
 281                 /* HOLE */
 282                 if (!buffer_mapped(&tmp)) {
 283                         /*
 284                          * first hole after going past the EOF, this is our
 285                          * last extent
 286                          */
 287                         if (length <= 0) {
 288                                 flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
 289                                 ret = fiemap_fill_next_extent(fieinfo, logical,
 290                                                               phys, size,
 291                                                               flags);
 292                                 break;
 293                         }
 294
 295                         length -= blk_to_logical(inode, 1);
 296
 297                         /* if we have holes up to/past EOF then we're done */
 298                         if (length <= 0)
 299                                 break;
 300
 301                         start_blk++;
 302                 } else {
 303                         if (length <= 0 && size) {
 304                                 ret = fiemap_fill_next_extent(fieinfo, logical,
 305                                                               phys, size,
 306                                                               flags);
 307                                 if (ret)
 308                                         break;
 309                         }
 310
 311                         logical = blk_to_logical(inode, start_blk);
 312                         phys = blk_to_logical(inode, tmp.b_blocknr);
 313                         size = tmp.b_size;
 314                         flags = FIEMAP_EXTENT_MERGED;
 315
 316                         length -= tmp.b_size;
 317                         start_blk += logical_to_blk(inode, size);
 318
 319                         /*
 320                          * if we are past the EOF we need to loop again to see
 321                          * if there is a hole so we can mark this extent as the
 322                          * last one, and if not keep mapping things until we
 323                          * find a hole, or we run out of slots in the extent
 324                          * array
 325                          */
 326                         if (length <= 0)
 327                                 continue;
 328
 329                         ret = fiemap_fill_next_extent(fieinfo, logical, phys,
 330                                                       size, flags);
 331                         if (ret)
 332                                 break;
 333                 }
 334                 cond_resched();
 335         } while (1);
 336
 337         mutex_unlock(&inode->i_mutex);
 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 #endif  /*  CONFIG_BLOCK  */
 348
 349 static int file_ioctl(struct file *filp, unsigned int cmd,
 350                 unsigned long arg)
 351 {
 352         struct inode *inode = filp->f_path.dentry->d_inode;
 353         int __user *p = (int __user *)arg;
 354
 355         switch (cmd) {
 356         case FIBMAP:
 357                 return ioctl_fibmap(filp, p);
 358         case FS_IOC_FIEMAP:
 359                 return ioctl_fiemap(filp, arg);
 360         case FIGETBSZ:
 361                 return put_user(inode->i_sb->s_blocksize, p);
 362         case FIONREAD:
 363                 return put_user(i_size_read(inode) - filp->f_pos, p);
 364         }
 365
 366         return vfs_ioctl(filp, cmd, arg);
 367 }
 368
 369 static int ioctl_fionbio(struct file *filp, int __user *argp)
 370 {
 371         unsigned int flag;
 372         int on, error;
 373
 374         error = get_user(on, argp);
 375         if (error)
 376                 return error;
 377         flag = O_NONBLOCK;
 378 #ifdef __sparc__
 379         /* SunOS compatibility item. */
 380         if (O_NONBLOCK != O_NDELAY)
 381                 flag |= O_NDELAY;
 382 #endif
 383         if (on)
 384                 filp->f_flags |= flag;
 385         else
 386                 filp->f_flags &= ~flag;
 387         return error;
 388 }
 389
 390 static int ioctl_fioasync(unsigned int fd, struct file *filp,
 391                           int __user *argp)
 392 {
 393         unsigned int flag;
 394         int on, error;
 395
 396         error = get_user(on, argp);
 397         if (error)
 398                 return error;
 399         flag = on ? FASYNC : 0;
 400
 401         /* Did FASYNC state change ? */
 402         if ((flag ^ filp->f_flags) & FASYNC) {
 403                 if (filp->f_op && filp->f_op->fasync)
 404                         error = filp->f_op->fasync(fd, filp, on);
 405                 else
 406                         error = -ENOTTY;
 407         }
 408         if (error)
 409                 return error;
 410
 411         if (on)
 412                 filp->f_flags |= FASYNC;
 413         else
 414                 filp->f_flags &= ~FASYNC;
 415         return error;
 416 }
 417
 418 /*
 419  * When you add any new common ioctls to the switches above and below
 420  * please update compat_sys_ioctl() too.
 421  *
 422  * do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d.
 423  * It's just a simple helper for sys_ioctl and compat_sys_ioctl.
 424  */
 425 int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
 426              unsigned long arg)
 427 {
 428         int error = 0;
 429         int __user *argp = (int __user *)arg;
 430
 431         switch (cmd) {
 432         case FIOCLEX:
 433                 set_close_on_exec(fd, 1);
 434                 break;
 435
 436         case FIONCLEX:
 437                 set_close_on_exec(fd, 0);
 438                 break;
 439
 440         case FIONBIO:
 441                 /* BKL needed to avoid races tweaking f_flags */
 442                 lock_kernel();
 443                 error = ioctl_fionbio(filp, argp);
 444                 unlock_kernel();
 445                 break;
 446
 447         case FIOASYNC:
 448                 /* BKL needed to avoid races tweaking f_flags */
 449                 lock_kernel();
 450                 error = ioctl_fioasync(fd, filp, argp);
 451                 unlock_kernel();
 452                 break;
 453
 454         case FIOQSIZE:
 455                 if (S_ISDIR(filp->f_path.dentry->d_inode->i_mode) ||
 456                     S_ISREG(filp->f_path.dentry->d_inode->i_mode) ||
 457                     S_ISLNK(filp->f_path.dentry->d_inode->i_mode)) {
 458                         loff_t res =
 459                                 inode_get_bytes(filp->f_path.dentry->d_inode);
 460                         error = copy_to_user((loff_t __user *)arg, &res,
 461                                              sizeof(res)) ? -EFAULT : 0;
 462                 } else
 463                         error = -ENOTTY;
 464                 break;
 465         default:
 466                 if (S_ISREG(filp->f_path.dentry->d_inode->i_mode))
 467                         error = file_ioctl(filp, cmd, arg);
 468                 else
 469                         error = vfs_ioctl(filp, cmd, arg);
 470                 break;
 471         }
 472         return error;
 473 }
 474
 475 SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 476 {
 477         struct file *filp;
 478         int error = -EBADF;
 479         int fput_needed;
 480
 481         filp = fget_light(fd, &fput_needed);
 482         if (!filp)
 483                 goto out;
 484
 485         error = security_file_ioctl(filp, cmd, arg);
 486         if (error)
 487                 goto out_fput;
 488
 489         error = do_vfs_ioctl(filp, fd, cmd, arg);
 490  out_fput:
 491         fput_light(filp, fput_needed);
 492  out:
 493         return error;
 494 }