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  */
   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 = -ENOTTY;
   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 __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 }
  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 __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 
  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         /*
  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 }
  390 EXPORT_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 
  404 int 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 }
  414 EXPORT_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  */
  425 int 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 
  449 static 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 
  468 static 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 
  491 static 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 
  513 static 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 
  528 static 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  */
  546 int 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 
  604 SYSCALL_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 }
Cache object: ed56805a7c6c07d51d1ec22ed8fa8c21
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FreeBSD/Linux Kernel Cross Reference sys/fs/ioctl.c

FreeBSD/Linux Kernel Cross Reference
sys/fs/ioctl.c
