fs/binfmt_misc.c

   1 /*
   2  *  binfmt_misc.c
   3  *
   4  *  Copyright (C) 1997 Richard Günther
   5  *
   6  *  binfmt_misc detects binaries via a magic or filename extension and invokes
   7  *  a specified wrapper. This should obsolete binfmt_java, binfmt_em86 and
   8  *  binfmt_mz.
   9  *
  10  *  1997-04-25 first version
  11  *  [...]
  12  *  1997-05-19 cleanup
  13  *  1997-06-26 hpa: pass the real filename rather than argv[0]
  14  *  1997-06-30 minor cleanup
  15  *  1997-08-09 removed extension stripping, locking cleanup
  16  *  2001-02-28 AV: rewritten into something that resembles C. Original didn't.
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21
  22 #include <linux/binfmts.h>
  23 #include <linux/slab.h>
  24 #include <linux/ctype.h>
  25 #include <linux/file.h>
  26 #include <linux/pagemap.h>
  27 #include <linux/namei.h>
  28 #include <linux/mount.h>
  29 #include <linux/syscalls.h>
  30
  31 #include <asm/uaccess.h>
  32
  33 enum {
  34         VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
  35 };
  36
  37 static LIST_HEAD(entries);
  38 static int enabled = 1;
  39
  40 enum {Enabled, Magic};
  41 #define MISC_FMT_PRESERVE_ARGV0 (1<<31)
  42 #define MISC_FMT_OPEN_BINARY (1<<30)
  43 #define MISC_FMT_CREDENTIALS (1<<29)
  44
  45 typedef struct {
  46         struct list_head list;
  47         unsigned long flags;            /* type, status, etc. */
  48         int offset;                     /* offset of magic */
  49         int size;                       /* size of magic/mask */
  50         char *magic;                    /* magic or filename extension */
  51         char *mask;                     /* mask, NULL for exact match */
  52         char *interpreter;              /* filename of interpreter */
  53         char *name;
  54         struct dentry *dentry;
  55 } Node;
  56
  57 static DEFINE_RWLOCK(entries_lock);
  58 static struct vfsmount *bm_mnt;
  59 static int entry_count;
  60
  61 /*
  62  * Check if we support the binfmt
  63  * if we do, return the node, else NULL
  64  * locking is done in load_misc_binary
  65  */
  66 static Node *check_file(struct linux_binprm *bprm)
  67 {
  68         char *p = strrchr(bprm->interp, '.');
  69         struct list_head *l;
  70
  71         list_for_each(l, &entries) {
  72                 Node *e = list_entry(l, Node, list);
  73                 char *s;
  74                 int j;
  75
  76                 if (!test_bit(Enabled, &e->flags))
  77                         continue;
  78
  79                 if (!test_bit(Magic, &e->flags)) {
  80                         if (p && !strcmp(e->magic, p + 1))
  81                                 return e;
  82                         continue;
  83                 }
  84
  85                 s = bprm->buf + e->offset;
  86                 if (e->mask) {
  87                         for (j = 0; j < e->size; j++)
  88                                 if ((*s++ ^ e->magic[j]) & e->mask[j])
  89                                         break;
  90                 } else {
  91                         for (j = 0; j < e->size; j++)
  92                                 if ((*s++ ^ e->magic[j]))
  93                                         break;
  94                 }
  95                 if (j == e->size)
  96                         return e;
  97         }
  98         return NULL;
  99 }
 100
 101 /*
 102  * the loader itself
 103  */
 104 static int load_misc_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 105 {
 106         Node *fmt;
 107         struct file * interp_file = NULL;
 108         char iname[BINPRM_BUF_SIZE];
 109         char *iname_addr = iname;
 110         int retval;
 111         int fd_binary = -1;
 112         struct files_struct *files = NULL;
 113
 114         retval = -ENOEXEC;
 115         if (!enabled)
 116                 goto _ret;
 117
 118         /* to keep locking time low, we copy the interpreter string */
 119         read_lock(&entries_lock);
 120         fmt = check_file(bprm);
 121         if (fmt)
 122                 strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
 123         read_unlock(&entries_lock);
 124         if (!fmt)
 125                 goto _ret;
 126
 127         if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
 128                 remove_arg_zero(bprm);
 129         }
 130
 131         if (fmt->flags & MISC_FMT_OPEN_BINARY) {
 132
 133                 files = current->files;
 134                 retval = unshare_files();
 135                 if (retval < 0)
 136                         goto _ret;
 137                 if (files == current->files) {
 138                         put_files_struct(files);
 139                         files = NULL;
 140                 }
 141                 /* if the binary should be opened on behalf of the
 142                  * interpreter than keep it open and assign descriptor
 143                  * to it */
 144                 fd_binary = get_unused_fd();
 145                 if (fd_binary < 0) {
 146                         retval = fd_binary;
 147                         goto _unshare;
 148                 }
 149                 fd_install(fd_binary, bprm->file);
 150
 151                 /* if the binary is not readable than enforce mm->dumpable=0
 152                    regardless of the interpreter's permissions */
 153                 if (file_permission(bprm->file, MAY_READ))
 154                         bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
 155
 156                 allow_write_access(bprm->file);
 157                 bprm->file = NULL;
 158
 159                 /* mark the bprm that fd should be passed to interp */
 160                 bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
 161                 bprm->interp_data = fd_binary;
 162
 163         } else {
 164                 allow_write_access(bprm->file);
 165                 fput(bprm->file);
 166                 bprm->file = NULL;
 167         }
 168         /* make argv[1] be the path to the binary */
 169         retval = copy_strings_kernel (1, &bprm->interp, bprm);
 170         if (retval < 0)
 171                 goto _error;
 172         bprm->argc++;
 173
 174         /* add the interp as argv[0] */
 175         retval = copy_strings_kernel (1, &iname_addr, bprm);
 176         if (retval < 0)
 177                 goto _error;
 178         bprm->argc ++;
 179
 180         bprm->interp = iname;   /* for binfmt_script */
 181
 182         interp_file = open_exec (iname);
 183         retval = PTR_ERR (interp_file);
 184         if (IS_ERR (interp_file))
 185                 goto _error;
 186
 187         bprm->file = interp_file;
 188         if (fmt->flags & MISC_FMT_CREDENTIALS) {
 189                 /*
 190                  * No need to call prepare_binprm(), it's already been
 191                  * done.  bprm->buf is stale, update from interp_file.
 192                  */
 193                 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
 194                 retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
 195         } else
 196                 retval = prepare_binprm (bprm);
 197
 198         if (retval < 0)
 199                 goto _error;
 200
 201         retval = search_binary_handler (bprm, regs);
 202         if (retval < 0)
 203                 goto _error;
 204
 205         if (files) {
 206                 steal_locks(files);
 207                 put_files_struct(files);
 208                 files = NULL;
 209         }
 210 _ret:
 211         return retval;
 212 _error:
 213         if (fd_binary > 0)
 214                 sys_close(fd_binary);
 215         bprm->interp_flags = 0;
 216         bprm->interp_data = 0;
 217 _unshare:
 218         if (files) {
 219                 put_files_struct(current->files);
 220                 current->files = files;
 221         }
 222         goto _ret;
 223 }
 224
 225 /* Command parsers */
 226
 227 /*
 228  * parses and copies one argument enclosed in del from *sp to *dp,
 229  * recognising the \x special.
 230  * returns pointer to the copied argument or NULL in case of an
 231  * error (and sets err) or null argument length.
 232  */
 233 static char *scanarg(char *s, char del)
 234 {
 235         char c;
 236
 237         while ((c = *s++) != del) {
 238                 if (c == '\\' && *s == 'x') {
 239                         s++;
 240                         if (!isxdigit(*s++))
 241                                 return NULL;
 242                         if (!isxdigit(*s++))
 243                                 return NULL;
 244                 }
 245         }
 246         return s;
 247 }
 248
 249 static int unquote(char *from)
 250 {
 251         char c = 0, *s = from, *p = from;
 252
 253         while ((c = *s++) != '\0') {
 254                 if (c == '\\' && *s == 'x') {
 255                         s++;
 256                         c = toupper(*s++);
 257                         *p = (c - (isdigit(c) ? '0' : 'A' - 10)) << 4;
 258                         c = toupper(*s++);
 259                         *p++ |= c - (isdigit(c) ? '0' : 'A' - 10);
 260                         continue;
 261                 }
 262                 *p++ = c;
 263         }
 264         return p - from;
 265 }
 266
 267 static inline char * check_special_flags (char * sfs, Node * e)
 268 {
 269         char * p = sfs;
 270         int cont = 1;
 271
 272         /* special flags */
 273         while (cont) {
 274                 switch (*p) {
 275                         case 'P':
 276                                 p++;
 277                                 e->flags |= MISC_FMT_PRESERVE_ARGV0;
 278                                 break;
 279                         case 'O':
 280                                 p++;
 281                                 e->flags |= MISC_FMT_OPEN_BINARY;
 282                                 break;
 283                         case 'C':
 284                                 p++;
 285                                 /* this flags also implies the
 286                                    open-binary flag */
 287                                 e->flags |= (MISC_FMT_CREDENTIALS |
 288                                                 MISC_FMT_OPEN_BINARY);
 289                                 break;
 290                         default:
 291                                 cont = 0;
 292                 }
 293         }
 294
 295         return p;
 296 }
 297 /*
 298  * This registers a new binary format, it recognises the syntax
 299  * ':name:type:offset:magic:mask:interpreter:flags'
 300  * where the ':' is the IFS, that can be chosen with the first char
 301  */
 302 static Node *create_entry(const char __user *buffer, size_t count)
 303 {
 304         Node *e;
 305         int memsize, err;
 306         char *buf, *p;
 307         char del;
 308
 309         /* some sanity checks */
 310         err = -EINVAL;
 311         if ((count < 11) || (count > 256))
 312                 goto out;
 313
 314         err = -ENOMEM;
 315         memsize = sizeof(Node) + count + 8;
 316         e = (Node *) kmalloc(memsize, GFP_USER);
 317         if (!e)
 318                 goto out;
 319
 320         p = buf = (char *)e + sizeof(Node);
 321
 322         memset(e, 0, sizeof(Node));
 323         if (copy_from_user(buf, buffer, count))
 324                 goto Efault;
 325
 326         del = *p++;     /* delimeter */
 327
 328         memset(buf+count, del, 8);
 329
 330         e->name = p;
 331         p = strchr(p, del);
 332         if (!p)
 333                 goto Einval;
 334         *p++ = '\0';
 335         if (!e->name[0] ||
 336             !strcmp(e->name, ".") ||
 337             !strcmp(e->name, "..") ||
 338             strchr(e->name, '/'))
 339                 goto Einval;
 340         switch (*p++) {
 341                 case 'E': e->flags = 1<<Enabled; break;
 342                 case 'M': e->flags = (1<<Enabled) | (1<<Magic); break;
 343                 default: goto Einval;
 344         }
 345         if (*p++ != del)
 346                 goto Einval;
 347         if (test_bit(Magic, &e->flags)) {
 348                 char *s = strchr(p, del);
 349                 if (!s)
 350                         goto Einval;
 351                 *s++ = '\0';
 352                 e->offset = simple_strtoul(p, &p, 10);
 353                 if (*p++)
 354                         goto Einval;
 355                 e->magic = p;
 356                 p = scanarg(p, del);
 357                 if (!p)
 358                         goto Einval;
 359                 p[-1] = '\0';
 360                 if (!e->magic[0])
 361                         goto Einval;
 362                 e->mask = p;
 363                 p = scanarg(p, del);
 364                 if (!p)
 365                         goto Einval;
 366                 p[-1] = '\0';
 367                 if (!e->mask[0])
 368                         e->mask = NULL;
 369                 e->size = unquote(e->magic);
 370                 if (e->mask && unquote(e->mask) != e->size)
 371                         goto Einval;
 372                 if (e->size + e->offset > BINPRM_BUF_SIZE)
 373                         goto Einval;
 374         } else {
 375                 p = strchr(p, del);
 376                 if (!p)
 377                         goto Einval;
 378                 *p++ = '\0';
 379                 e->magic = p;
 380                 p = strchr(p, del);
 381                 if (!p)
 382                         goto Einval;
 383                 *p++ = '\0';
 384                 if (!e->magic[0] || strchr(e->magic, '/'))
 385                         goto Einval;
 386                 p = strchr(p, del);
 387                 if (!p)
 388                         goto Einval;
 389                 *p++ = '\0';
 390         }
 391         e->interpreter = p;
 392         p = strchr(p, del);
 393         if (!p)
 394                 goto Einval;
 395         *p++ = '\0';
 396         if (!e->interpreter[0])
 397                 goto Einval;
 398
 399
 400         p = check_special_flags (p, e);
 401
 402         if (*p == '\n')
 403                 p++;
 404         if (p != buf + count)
 405                 goto Einval;
 406         return e;
 407
 408 out:
 409         return ERR_PTR(err);
 410
 411 Efault:
 412         kfree(e);
 413         return ERR_PTR(-EFAULT);
 414 Einval:
 415         kfree(e);
 416         return ERR_PTR(-EINVAL);
 417 }
 418
 419 /*
 420  * Set status of entry/binfmt_misc:
 421  * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
 422  */
 423 static int parse_command(const char __user *buffer, size_t count)
 424 {
 425         char s[4];
 426
 427         if (!count)
 428                 return 0;
 429         if (count > 3)
 430                 return -EINVAL;
 431         if (copy_from_user(s, buffer, count))
 432                 return -EFAULT;
 433         if (s[count-1] == '\n')
 434                 count--;
 435         if (count == 1 && s[0] == '0')
 436                 return 1;
 437         if (count == 1 && s[0] == '1')
 438                 return 2;
 439         if (count == 2 && s[0] == '-' && s[1] == '1')
 440                 return 3;
 441         return -EINVAL;
 442 }
 443
 444 /* generic stuff */
 445
 446 static void entry_status(Node *e, char *page)
 447 {
 448         char *dp;
 449         char *status = "disabled";
 450         const char * flags = "flags: ";
 451
 452         if (test_bit(Enabled, &e->flags))
 453                 status = "enabled";
 454
 455         if (!VERBOSE_STATUS) {
 456                 sprintf(page, "%s\n", status);
 457                 return;
 458         }
 459
 460         sprintf(page, "%s\ninterpreter %s\n", status, e->interpreter);
 461         dp = page + strlen(page);
 462
 463         /* print the special flags */
 464         sprintf (dp, "%s", flags);
 465         dp += strlen (flags);
 466         if (e->flags & MISC_FMT_PRESERVE_ARGV0) {
 467                 *dp ++ = 'P';
 468         }
 469         if (e->flags & MISC_FMT_OPEN_BINARY) {
 470                 *dp ++ = 'O';
 471         }
 472         if (e->flags & MISC_FMT_CREDENTIALS) {
 473                 *dp ++ = 'C';
 474         }
 475         *dp ++ = '\n';
 476
 477
 478         if (!test_bit(Magic, &e->flags)) {
 479                 sprintf(dp, "extension .%s\n", e->magic);
 480         } else {
 481                 int i;
 482
 483                 sprintf(dp, "offset %i\nmagic ", e->offset);
 484                 dp = page + strlen(page);
 485                 for (i = 0; i < e->size; i++) {
 486                         sprintf(dp, "%02x", 0xff & (int) (e->magic[i]));
 487                         dp += 2;
 488                 }
 489                 if (e->mask) {
 490                         sprintf(dp, "\nmask ");
 491                         dp += 6;
 492                         for (i = 0; i < e->size; i++) {
 493                                 sprintf(dp, "%02x", 0xff & (int) (e->mask[i]));
 494                                 dp += 2;
 495                         }
 496                 }
 497                 *dp++ = '\n';
 498                 *dp = '\0';
 499         }
 500 }
 501
 502 static struct inode *bm_get_inode(struct super_block *sb, int mode)
 503 {
 504         struct inode * inode = new_inode(sb);
 505
 506         if (inode) {
 507                 inode->i_mode = mode;
 508                 inode->i_uid = 0;
 509                 inode->i_gid = 0;
 510                 inode->i_blksize = PAGE_CACHE_SIZE;
 511                 inode->i_blocks = 0;
 512                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 513                         current_fs_time(inode->i_sb);
 514         }
 515         return inode;
 516 }
 517
 518 static void bm_clear_inode(struct inode *inode)
 519 {
 520         kfree(inode->u.generic_ip);
 521 }
 522
 523 static void kill_node(Node *e)
 524 {
 525         struct dentry *dentry;
 526
 527         write_lock(&entries_lock);
 528         dentry = e->dentry;
 529         if (dentry) {
 530                 list_del_init(&e->list);
 531                 e->dentry = NULL;
 532         }
 533         write_unlock(&entries_lock);
 534
 535         if (dentry) {
 536                 dentry->d_inode->i_nlink--;
 537                 d_drop(dentry);
 538                 dput(dentry);
 539                 simple_release_fs(&bm_mnt, &entry_count);
 540         }
 541 }
 542
 543 /* /<entry> */
 544
 545 static ssize_t
 546 bm_entry_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
 547 {
 548         Node *e = file->f_dentry->d_inode->u.generic_ip;
 549         loff_t pos = *ppos;
 550         ssize_t res;
 551         char *page;
 552         int len;
 553
 554         if (!(page = (char*) __get_free_page(GFP_KERNEL)))
 555                 return -ENOMEM;
 556
 557         entry_status(e, page);
 558         len = strlen(page);
 559
 560         res = -EINVAL;
 561         if (pos < 0)
 562                 goto out;
 563         res = 0;
 564         if (pos >= len)
 565                 goto out;
 566         if (len < pos + nbytes)
 567                 nbytes = len - pos;
 568         res = -EFAULT;
 569         if (copy_to_user(buf, page + pos, nbytes))
 570                 goto out;
 571         *ppos = pos + nbytes;
 572         res = nbytes;
 573 out:
 574         free_page((unsigned long) page);
 575         return res;
 576 }
 577
 578 static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
 579                                 size_t count, loff_t *ppos)
 580 {
 581         struct dentry *root;
 582         Node *e = file->f_dentry->d_inode->u.generic_ip;
 583         int res = parse_command(buffer, count);
 584
 585         switch (res) {
 586                 case 1: clear_bit(Enabled, &e->flags);
 587                         break;
 588                 case 2: set_bit(Enabled, &e->flags);
 589                         break;
 590                 case 3: root = dget(file->f_vfsmnt->mnt_sb->s_root);
 591                         down(&root->d_inode->i_sem);
 592
 593                         kill_node(e);
 594
 595                         up(&root->d_inode->i_sem);
 596                         dput(root);
 597                         break;
 598                 default: return res;
 599         }
 600         return count;
 601 }
 602
 603 static struct file_operations bm_entry_operations = {
 604         .read           = bm_entry_read,
 605         .write          = bm_entry_write,
 606 };
 607
 608 /* /register */
 609
 610 static ssize_t bm_register_write(struct file *file, const char __user *buffer,
 611                                size_t count, loff_t *ppos)
 612 {
 613         Node *e;
 614         struct inode *inode;
 615         struct dentry *root, *dentry;
 616         struct super_block *sb = file->f_vfsmnt->mnt_sb;
 617         int err = 0;
 618
 619         e = create_entry(buffer, count);
 620
 621         if (IS_ERR(e))
 622                 return PTR_ERR(e);
 623
 624         root = dget(sb->s_root);
 625         down(&root->d_inode->i_sem);
 626         dentry = lookup_one_len(e->name, root, strlen(e->name));
 627         err = PTR_ERR(dentry);
 628         if (IS_ERR(dentry))
 629                 goto out;
 630
 631         err = -EEXIST;
 632         if (dentry->d_inode)
 633                 goto out2;
 634
 635         inode = bm_get_inode(sb, S_IFREG | 0644);
 636
 637         err = -ENOMEM;
 638         if (!inode)
 639                 goto out2;
 640
 641         err = simple_pin_fs("binfmt_misc", &bm_mnt, &entry_count);
 642         if (err) {
 643                 iput(inode);
 644                 inode = NULL;
 645                 goto out2;
 646         }
 647
 648         e->dentry = dget(dentry);
 649         inode->u.generic_ip = e;
 650         inode->i_fop = &bm_entry_operations;
 651
 652         d_instantiate(dentry, inode);
 653         write_lock(&entries_lock);
 654         list_add(&e->list, &entries);
 655         write_unlock(&entries_lock);
 656
 657         err = 0;
 658 out2:
 659         dput(dentry);
 660 out:
 661         up(&root->d_inode->i_sem);
 662         dput(root);
 663
 664         if (err) {
 665                 kfree(e);
 666                 return -EINVAL;
 667         }
 668         return count;
 669 }
 670
 671 static struct file_operations bm_register_operations = {
 672         .write          = bm_register_write,
 673 };
 674
 675 /* /status */
 676
 677 static ssize_t
 678 bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 679 {
 680         char *s = enabled ? "enabled" : "disabled";
 681         int len = strlen(s);
 682         loff_t pos = *ppos;
 683
 684         if (pos < 0)
 685                 return -EINVAL;
 686         if (pos >= len)
 687                 return 0;
 688         if (len < pos + nbytes)
 689                 nbytes = len - pos;
 690         if (copy_to_user(buf, s + pos, nbytes))
 691                 return -EFAULT;
 692         *ppos = pos + nbytes;
 693         return nbytes;
 694 }
 695
 696 static ssize_t bm_status_write(struct file * file, const char __user * buffer,
 697                 size_t count, loff_t *ppos)
 698 {
 699         int res = parse_command(buffer, count);
 700         struct dentry *root;
 701
 702         switch (res) {
 703                 case 1: enabled = 0; break;
 704                 case 2: enabled = 1; break;
 705                 case 3: root = dget(file->f_vfsmnt->mnt_sb->s_root);
 706                         down(&root->d_inode->i_sem);
 707
 708                         while (!list_empty(&entries))
 709                                 kill_node(list_entry(entries.next, Node, list));
 710
 711                         up(&root->d_inode->i_sem);
 712                         dput(root);
 713                 default: return res;
 714         }
 715         return count;
 716 }
 717
 718 static struct file_operations bm_status_operations = {
 719         .read           = bm_status_read,
 720         .write          = bm_status_write,
 721 };
 722
 723 /* Superblock handling */
 724
 725 static struct super_operations s_ops = {
 726         .statfs         = simple_statfs,
 727         .clear_inode    = bm_clear_inode,
 728 };
 729
 730 static int bm_fill_super(struct super_block * sb, void * data, int silent)
 731 {
 732         static struct tree_descr bm_files[] = {
 733                 [1] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
 734                 [2] = {"register", &bm_register_operations, S_IWUSR},
 735                 /* last one */ {""}
 736         };
 737         int err = simple_fill_super(sb, 0x42494e4d, bm_files);
 738         if (!err)
 739                 sb->s_op = &s_ops;
 740         return err;
 741 }
 742
 743 static struct super_block *bm_get_sb(struct file_system_type *fs_type,
 744         int flags, const char *dev_name, void *data)
 745 {
 746         return get_sb_single(fs_type, flags, data, bm_fill_super);
 747 }
 748
 749 static struct linux_binfmt misc_format = {
 750         .module = THIS_MODULE,
 751         .load_binary = load_misc_binary,
 752 };
 753
 754 static struct file_system_type bm_fs_type = {
 755         .owner          = THIS_MODULE,
 756         .name           = "binfmt_misc",
 757         .get_sb         = bm_get_sb,
 758         .kill_sb        = kill_litter_super,
 759 };
 760
 761 static int __init init_misc_binfmt(void)
 762 {
 763         int err = register_filesystem(&bm_fs_type);
 764         if (!err) {
 765                 err = register_binfmt(&misc_format);
 766                 if (err)
 767                         unregister_filesystem(&bm_fs_type);
 768         }
 769         return err;
 770 }
 771
 772 static void __exit exit_misc_binfmt(void)
 773 {
 774         unregister_binfmt(&misc_format);
 775         unregister_filesystem(&bm_fs_type);
 776 }
 777
 778 core_initcall(init_misc_binfmt);
 779 module_exit(exit_misc_binfmt);
 780 MODULE_LICENSE("GPL");