fs/exec.c

   1 /*
   2  *  linux/fs/exec.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * #!-checking implemented by tytso.
   9  */
  10 /*
  11  * Demand-loading implemented 01.12.91 - no need to read anything but
  12  * the header into memory. The inode of the executable is put into
  13  * "current->executable", and page faults do the actual loading. Clean.
  14  *
  15  * Once more I can proudly say that linux stood up to being changed: it
  16  * was less than 2 hours work to get demand-loading completely implemented.
  17  *
  18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19  * current->executable is only used by the procfs.  This allows a dispatch
  20  * table to check for several different types  of binary formats.  We keep
  21  * trying until we recognize the file or we run out of supported binary
  22  * formats.
  23  */
  24
  25 #include <linux/config.h>
  26 #include <linux/slab.h>
  27 #include <linux/file.h>
  28 #include <linux/mman.h>
  29 #include <linux/a.out.h>
  30 #include <linux/stat.h>
  31 #include <linux/fcntl.h>
  32 #include <linux/smp_lock.h>
  33 #include <linux/init.h>
  34
  35 #include <asm/uaccess.h>
  36 #include <asm/pgtable.h>
  37 #include <asm/mmu_context.h>
  38
  39 #ifdef CONFIG_KMOD
  40 #include <linux/kmod.h>
  41 #endif
  42
  43 /*
  44  * Here are the actual binaries that will be accepted:
  45  * add more with "register_binfmt()" if using modules...
  46  *
  47  * These are defined again for the 'real' modules if you are using a
  48  * module definition for these routines.
  49  */
  50
  51 static struct linux_binfmt *formats = (struct linux_binfmt *) NULL;
  52
  53 void __init binfmt_setup(void)
  54 {
  55 #ifdef CONFIG_BINFMT_MISC
  56         init_misc_binfmt();
  57 #endif
  58
  59 #ifdef CONFIG_BINFMT_ELF
  60         init_elf_binfmt();
  61 #endif
  62
  63 #ifdef CONFIG_BINFMT_ELF32
  64         init_elf32_binfmt();
  65 #endif
  66
  67 #ifdef CONFIG_BINFMT_AOUT
  68         init_aout_binfmt();
  69 #endif
  70
  71 #ifdef CONFIG_BINFMT_AOUT32
  72         init_aout32_binfmt();
  73 #endif
  74
  75 #ifdef CONFIG_BINFMT_EM86
  76         init_em86_binfmt();
  77 #endif
  78
  79         /* This cannot be configured out of the kernel */
  80         init_script_binfmt();
  81 }
  82
  83 int register_binfmt(struct linux_binfmt * fmt)
  84 {
  85         struct linux_binfmt ** tmp = &formats;
  86
  87         if (!fmt)
  88                 return -EINVAL;
  89         if (fmt->next)
  90                 return -EBUSY;
  91         while (*tmp) {
  92                 if (fmt == *tmp)
  93                         return -EBUSY;
  94                 tmp = &(*tmp)->next;
  95         }
  96         fmt->next = formats;
  97         formats = fmt;
  98         return 0;
  99 }
 100
 101 #ifdef CONFIG_MODULES
 102 int unregister_binfmt(struct linux_binfmt * fmt)
 103 {
 104         struct linux_binfmt ** tmp = &formats;
 105
 106         while (*tmp) {
 107                 if (fmt == *tmp) {
 108                         *tmp = fmt->next;
 109                         return 0;
 110                 }
 111                 tmp = &(*tmp)->next;
 112         }
 113         return -EINVAL;
 114 }
 115 #endif  /* CONFIG_MODULES */
 116
 117 /* N.B. Error returns must be < 0 */
 118 int open_dentry(struct dentry * dentry, int mode)
 119 {
 120         struct inode * inode = dentry->d_inode;
 121         struct file * f;
 122         struct list_head * l = NULL;
 123         int fd, error;
 124
 125         if (inode->i_sb)
 126                 l = &inode->i_sb->s_files;
 127
 128         error = -EINVAL;
 129         if (!inode->i_op || !inode->i_op->default_file_ops)
 130                 goto out;
 131         fd = get_unused_fd();
 132         if (fd >= 0) {
 133                 error = -ENFILE;
 134                 f = get_empty_filp();
 135                 if (!f)
 136                         goto out_fd;
 137                 f->f_flags = mode;
 138                 f->f_mode = (mode+1) & O_ACCMODE;
 139                 f->f_dentry = dentry;
 140                 f->f_pos = 0;
 141                 f->f_reada = 0;
 142                 f->f_op = inode->i_op->default_file_ops;
 143                 if (f->f_op->open) {
 144                         error = f->f_op->open(inode,f);
 145                         if (error)
 146                                 goto out_filp;
 147                 }
 148                 file_move(f, l);
 149                 fd_install(fd, f);
 150                 dget(dentry);
 151         }
 152         return fd;
 153
 154 out_filp:
 155         if (error > 0)
 156                 error = -EIO;
 157         put_filp(f);
 158 out_fd:
 159         put_unused_fd(fd);
 160 out:
 161         return error;
 162 }
 163
 164 /*
 165  * Note that a shared library must be both readable and executable due to
 166  * security reasons.
 167  *
 168  * Also note that we take the address to load from from the file itself.
 169  */
 170 asmlinkage int sys_uselib(const char * library)
 171 {
 172         int fd, retval;
 173         struct file * file;
 174         struct linux_binfmt * fmt;
 175
 176         lock_kernel();
 177         fd = sys_open(library, 0, 0);
 178         retval = fd;
 179         if (fd < 0)
 180                 goto out;
 181         file = fget(fd);
 182         retval = -ENOEXEC;
 183         if (file && file->f_dentry && file->f_op && file->f_op->read) {
 184                 for (fmt = formats ; fmt ; fmt = fmt->next) {
 185                         int (*fn)(int) = fmt->load_shlib;
 186                         if (!fn)
 187                                 continue;
 188                         /* N.B. Should use file instead of fd */
 189                         retval = fn(fd);
 190                         if (retval != -ENOEXEC)
 191                                 break;
 192                 }
 193         }
 194         fput(file);
 195         sys_close(fd);
 196 out:
 197         unlock_kernel();
 198         return retval;
 199 }
 200
 201 /*
 202  * count() counts the number of arguments/envelopes
 203  */
 204 static int count(char ** argv)
 205 {
 206         int i = 0;
 207
 208         if (argv != NULL) {
 209                 for (;;) {
 210                         char * p;
 211                         int error;
 212
 213                         error = get_user(p,argv);
 214                         if (error)
 215                                 return error;
 216                         if (!p)
 217                                 break;
 218                         argv++;
 219                         i++;
 220                 }
 221         }
 222         return i;
 223 }
 224
 225 /*
 226  * 'copy_strings()' copies argument/envelope strings from user
 227  * memory to free pages in kernel mem. These are in a format ready
 228  * to be put directly into the top of new user memory.
 229  */
 230 int copy_strings(int argc,char ** argv, struct linux_binprm *bprm)
 231 {
 232         while (argc-- > 0) {
 233                 char *str;
 234                 int len;
 235                 unsigned long pos;
 236
 237                 if (get_user(str, argv+argc) || !str || !(len = strlen_user(str)))
 238                         return -EFAULT;
 239                 if (bprm->p < len)
 240                         return -E2BIG;
 241
 242                 bprm->p -= len;
 243                 /* XXX: add architecture specific overflow check here. */
 244
 245                 pos = bprm->p;
 246                 while (len) {
 247                         char *pag;
 248                         int offset, bytes_to_copy;
 249
 250                         offset = pos % PAGE_SIZE;
 251                         if (!(pag = (char *) bprm->page[pos/PAGE_SIZE]) &&
 252                             !(pag = (char *) bprm->page[pos/PAGE_SIZE] =
 253                               (unsigned long *) get_free_page(GFP_USER)))
 254                                 return -ENOMEM;
 255
 256                         bytes_to_copy = PAGE_SIZE - offset;
 257                         if (bytes_to_copy > len)
 258                                 bytes_to_copy = len;
 259                         if (copy_from_user(pag + offset, str, bytes_to_copy))
 260                                 return -EFAULT;
 261
 262                         pos += bytes_to_copy;
 263                         str += bytes_to_copy;
 264                         len -= bytes_to_copy;
 265                 }
 266         }
 267         return 0;
 268 }
 269
 270 /*
 271  * Like copy_strings, but get argv and its values from kernel memory.
 272  */
 273 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 274 {
 275         int r;
 276         mm_segment_t oldfs = get_fs();
 277         set_fs(KERNEL_DS);
 278         r = copy_strings(argc, argv, bprm);
 279         set_fs(oldfs);
 280         return r;
 281 }
 282
 283 int setup_arg_pages(struct linux_binprm *bprm)
 284 {
 285         unsigned long stack_base;
 286         struct vm_area_struct *mpnt;
 287         int i;
 288
 289         stack_base = STACK_TOP - MAX_ARG_PAGES*PAGE_SIZE;
 290
 291         bprm->p += stack_base;
 292         if (bprm->loader)
 293                 bprm->loader += stack_base;
 294         bprm->exec += stack_base;
 295
 296         mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 297         if (!mpnt)
 298                 return -ENOMEM;
 299
 300         {
 301                 mpnt->vm_mm = current->mm;
 302                 mpnt->vm_start = PAGE_MASK & (unsigned long) bprm->p;
 303                 mpnt->vm_end = STACK_TOP;
 304                 mpnt->vm_page_prot = PAGE_COPY;
 305                 mpnt->vm_flags = VM_STACK_FLAGS;
 306                 mpnt->vm_ops = NULL;
 307                 mpnt->vm_offset = 0;
 308                 mpnt->vm_file = NULL;
 309                 mpnt->vm_pte = 0;
 310                 insert_vm_struct(current->mm, mpnt);
 311                 current->mm->total_vm = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
 312         }
 313
 314         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
 315                 if (bprm->page[i]) {
 316                         current->mm->rss++;
 317                         put_dirty_page(current,bprm->page[i],stack_base);
 318                 }
 319                 stack_base += PAGE_SIZE;
 320         }
 321
 322         return 0;
 323 }
 324
 325 /*
 326  * Read in the complete executable. This is used for "-N" files
 327  * that aren't on a block boundary, and for files on filesystems
 328  * without get_block support.
 329  */
 330 int read_exec(struct dentry *dentry, unsigned long offset,
 331         char * addr, unsigned long count, int to_kmem)
 332 {
 333         struct file file;
 334         struct inode * inode = dentry->d_inode;
 335         int result = -ENOEXEC;
 336
 337         if (!inode->i_op || !inode->i_op->default_file_ops)
 338                 goto end_readexec;
 339         if (init_private_file(&file, dentry, 1))
 340                 goto end_readexec;
 341         if (!file.f_op->read)
 342                 goto close_readexec;
 343         if (file.f_op->llseek) {
 344                 if (file.f_op->llseek(&file,offset,0) != offset)
 345                         goto close_readexec;
 346         } else
 347                 file.f_pos = offset;
 348         if (to_kmem) {
 349                 mm_segment_t old_fs = get_fs();
 350                 set_fs(get_ds());
 351                 result = file.f_op->read(&file, addr, count, &file.f_pos);
 352                 set_fs(old_fs);
 353         } else {
 354                 result = verify_area(VERIFY_WRITE, addr, count);
 355                 if (result)
 356                         goto close_readexec;
 357                 result = file.f_op->read(&file, addr, count, &file.f_pos);
 358         }
 359 close_readexec:
 360         if (file.f_op->release)
 361                 file.f_op->release(inode,&file);
 362 end_readexec:
 363         return result;
 364 }
 365
 366 static int exec_mmap(void)
 367 {
 368         struct mm_struct * mm, * old_mm;
 369
 370         old_mm = current->mm;
 371         if (old_mm && atomic_read(&old_mm->mm_users) == 1) {
 372                 flush_cache_mm(old_mm);
 373                 mm_release();
 374                 release_segments(old_mm);
 375                 exit_mmap(old_mm);
 376                 flush_tlb_mm(old_mm);
 377                 return 0;
 378         }
 379
 380         mm = mm_alloc();
 381         if (mm) {
 382                 struct mm_struct *active_mm = current->active_mm;
 383
 384                 mm->cpu_vm_mask = (1UL << smp_processor_id());
 385                 current->mm = mm;
 386                 current->active_mm = mm;
 387                 switch_mm(active_mm, mm);
 388                 mm_release();
 389                 if (old_mm) {
 390                         if (active_mm != old_mm) BUG();
 391                         mmput(old_mm);
 392                         return 0;
 393                 }
 394                 mmdrop(active_mm);
 395                 return 0;
 396         }
 397         return -ENOMEM;
 398 }
 399
 400 /*
 401  * This function makes sure the current process has its own signal table,
 402  * so that flush_signal_handlers can later reset the handlers without
 403  * disturbing other processes.  (Other processes might share the signal
 404  * table via the CLONE_SIGHAND option to clone().)
 405  */
 406
 407 static inline int make_private_signals(void)
 408 {
 409         struct signal_struct * newsig;
 410
 411         if (atomic_read(&current->sig->count) <= 1)
 412                 return 0;
 413         newsig = kmalloc(sizeof(*newsig), GFP_KERNEL);
 414         if (newsig == NULL)
 415                 return -ENOMEM;
 416         spin_lock_init(&newsig->siglock);
 417         atomic_set(&newsig->count, 1);
 418         memcpy(newsig->action, current->sig->action, sizeof(newsig->action));
 419         current->sig = newsig;
 420         return 0;
 421 }
 422
 423 /*
 424  * If make_private_signals() made a copy of the signal table, decrement the
 425  * refcount of the original table, and free it if necessary.
 426  * We don't do that in make_private_signals() so that we can back off
 427  * in flush_old_exec() if an error occurs after calling make_private_signals().
 428  */
 429
 430 static inline void release_old_signals(struct signal_struct * oldsig)
 431 {
 432         if (current->sig == oldsig)
 433                 return;
 434         if (atomic_dec_and_test(&oldsig->count))
 435                 kfree(oldsig);
 436 }
 437
 438 /*
 439  * These functions flushes out all traces of the currently running executable
 440  * so that a new one can be started
 441  */
 442
 443 static inline void flush_old_files(struct files_struct * files)
 444 {
 445         unsigned long j;
 446
 447         j = 0;
 448         for (;;) {
 449                 unsigned long set, i;
 450
 451                 i = j * __NFDBITS;
 452                 if (i >= files->max_fds)
 453                         break;
 454                 set = xchg(&files->close_on_exec.fds_bits[j], 0);
 455                 j++;
 456                 for ( ; set ; i++,set >>= 1) {
 457                         if (set & 1)
 458                                 sys_close(i);
 459                 }
 460         }
 461 }
 462
 463 int flush_old_exec(struct linux_binprm * bprm)
 464 {
 465         char * name;
 466         int i, ch, retval;
 467         struct signal_struct * oldsig;
 468
 469         /*
 470          * Make sure we have a private signal table
 471          */
 472         oldsig = current->sig;
 473         retval = make_private_signals();
 474         if (retval) goto flush_failed;
 475
 476         /*
 477          * Release all of the old mmap stuff
 478          */
 479         retval = exec_mmap();
 480         if (retval) goto mmap_failed;
 481
 482         /* This is the point of no return */
 483         release_old_signals(oldsig);
 484
 485         if (current->euid == current->uid && current->egid == current->gid)
 486                 current->dumpable = 1;
 487         name = bprm->filename;
 488         for (i=0; (ch = *(name++)) != '\0';) {
 489                 if (ch == '/')
 490                         i = 0;
 491                 else
 492                         if (i < 15)
 493                                 current->comm[i++] = ch;
 494         }
 495         current->comm[i] = '\0';
 496
 497         flush_thread();
 498
 499         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
 500             permission(bprm->dentry->d_inode,MAY_READ))
 501                 current->dumpable = 0;
 502
 503         flush_signal_handlers(current);
 504         flush_old_files(current->files);
 505
 506         return 0;
 507
 508 mmap_failed:
 509         if (current->sig != oldsig)
 510                 kfree(current->sig);
 511 flush_failed:
 512         current->sig = oldsig;
 513         return retval;
 514 }
 515
 516 /*
 517  * We mustn't allow tracing of suid binaries, unless
 518  * the tracer has the capability to trace anything..
 519  */
 520 static inline int must_not_trace_exec(struct task_struct * p)
 521 {
 522         return (p->flags & PF_PTRACED) && !cap_raised(p->p_pptr->cap_effective, CAP_SYS_PTRACE);
 523 }
 524
 525 /*
 526  * Fill the binprm structure from the inode.
 527  * Check permissions, then read the first 512 bytes
 528  */
 529 int prepare_binprm(struct linux_binprm *bprm)
 530 {
 531         int mode;
 532         int retval,id_change,cap_raised;
 533         struct inode * inode = bprm->dentry->d_inode;
 534
 535         mode = inode->i_mode;
 536         if (!S_ISREG(mode))                     /* must be regular file */
 537                 return -EACCES;
 538         if (!(mode & 0111))                     /* with at least _one_ execute bit set */
 539                 return -EACCES;
 540         if (IS_NOEXEC(inode))                   /* FS mustn't be mounted noexec */
 541                 return -EACCES;
 542         if (!inode->i_sb)
 543                 return -EACCES;
 544         if ((retval = permission(inode, MAY_EXEC)) != 0)
 545                 return retval;
 546         /* better not execute files which are being written to */
 547         if (atomic_read(&inode->i_writecount) > 0)
 548                 return -ETXTBSY;
 549
 550         bprm->e_uid = current->euid;
 551         bprm->e_gid = current->egid;
 552         id_change = cap_raised = 0;
 553
 554         /* Set-uid? */
 555         if (mode & S_ISUID) {
 556                 bprm->e_uid = inode->i_uid;
 557                 if (bprm->e_uid != current->euid)
 558                         id_change = 1;
 559         }
 560
 561         /* Set-gid? */
 562         /*
 563          * If setgid is set but no group execute bit then this
 564          * is a candidate for mandatory locking, not a setgid
 565          * executable.
 566          */
 567         if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 568                 bprm->e_gid = inode->i_gid;
 569                 if (!in_group_p(bprm->e_gid))
 570                         id_change = 1;
 571         }
 572
 573         /* We don't have VFS support for capabilities yet */
 574         cap_clear(bprm->cap_inheritable);
 575         cap_clear(bprm->cap_permitted);
 576         cap_clear(bprm->cap_effective);
 577
 578         /*  To support inheritance of root-permissions and suid-root
 579          *  executables under compatibility mode, we raise the
 580          *  effective and inherited bitmasks of the executable file
 581          *  (translation: we set the executable "capability dumb" and
 582          *  set the allowed set to maximum). We don't set any forced
 583          *  bits.
 584          *
 585          *  If only the real uid is 0, we only raise the inheritable
 586          *  bitmask of the executable file (translation: we set the
 587          *  allowed set to maximum and the application to "capability
 588          *  smart").
 589          */
 590
 591         if (!issecure(SECURE_NOROOT)) {
 592                 if (bprm->e_uid == 0 || current->uid == 0)
 593                         cap_set_full(bprm->cap_inheritable);
 594                 if (bprm->e_uid == 0)
 595                         cap_set_full(bprm->cap_effective);
 596         }
 597
 598         /* Only if pP' is _not_ a subset of pP, do we consider there
 599          * has been a capability related "change of capability".  In
 600          * such cases, we need to check that the elevation of
 601          * privilege does not go against other system constraints.
 602          * The new Permitted set is defined below -- see (***). */
 603         {
 604                 kernel_cap_t working =
 605                         cap_combine(bprm->cap_permitted,
 606                                     cap_intersect(bprm->cap_inheritable,
 607                                                   current->cap_inheritable));
 608                 if (!cap_issubset(working, current->cap_permitted)) {
 609                         cap_raised = 1;
 610                 }
 611         }
 612
 613         if (id_change || cap_raised) {
 614                 /* We can't suid-execute if we're sharing parts of the executable */
 615                 /* or if we're being traced (or if suid execs are not allowed)    */
 616                 /* (current->mm->mm_users > 1 is ok, as we'll get a new mm anyway)   */
 617                 if (IS_NOSUID(inode)
 618                     || must_not_trace_exec(current)
 619                     || (atomic_read(&current->fs->count) > 1)
 620                     || (atomic_read(&current->sig->count) > 1)
 621                     || (atomic_read(&current->files->count) > 1)) {
 622                         if (id_change && !capable(CAP_SETUID))
 623                                 return -EPERM;
 624                         if (cap_raised && !capable(CAP_SETPCAP))
 625                                 return -EPERM;
 626                 }
 627         }
 628
 629         memset(bprm->buf,0,sizeof(bprm->buf));
 630         return read_exec(bprm->dentry,0,bprm->buf,128,1);
 631 }
 632
 633 /*
 634  * This function is used to produce the new IDs and capabilities
 635  * from the old ones and the file's capabilities.
 636  *
 637  * The formula used for evolving capabilities is:
 638  *
 639  *       pI' = pI
 640  * (***) pP' = fP | (fI & pI)
 641  *       pE' = pP' & fE          [NB. fE is 0 or ~0]
 642  *
 643  * I=Inheritable, P=Permitted, E=Effective // p=process, f=file
 644  * ' indicates post-exec().
 645  */
 646
 647 void compute_creds(struct linux_binprm *bprm)
 648 {
 649         int new_permitted = cap_t(bprm->cap_permitted) |
 650                 (cap_t(bprm->cap_inheritable) &
 651                  cap_t(current->cap_inheritable));
 652
 653         /* For init, we want to retain the capabilities set
 654          * in the init_task struct. Thus we skip the usual
 655          * capability rules */
 656         if (current->pid != 1) {
 657                 cap_t(current->cap_permitted) = new_permitted;
 658                 cap_t(current->cap_effective) = new_permitted &
 659                                                 cap_t(bprm->cap_effective);
 660         }
 661
 662         /* AUD: Audit candidate if current->cap_effective is set */
 663
 664         current->suid = current->euid = current->fsuid = bprm->e_uid;
 665         current->sgid = current->egid = current->fsgid = bprm->e_gid;
 666         if (current->euid != current->uid || current->egid != current->gid ||
 667             !cap_issubset(new_permitted, current->cap_permitted))
 668                 current->dumpable = 0;
 669 }
 670
 671
 672 void remove_arg_zero(struct linux_binprm *bprm)
 673 {
 674         if (bprm->argc) {
 675                 unsigned long offset;
 676                 char * page;
 677                 offset = bprm->p % PAGE_SIZE;
 678                 page = (char*)bprm->page[bprm->p/PAGE_SIZE];
 679                 while(bprm->p++,*(page+offset++))
 680                         if(offset==PAGE_SIZE){
 681                                 offset=0;
 682                                 page = (char*)bprm->page[bprm->p/PAGE_SIZE];
 683                         }
 684                 bprm->argc--;
 685         }
 686 }
 687
 688 /*
 689  * cycle the list of binary formats handler, until one recognizes the image
 690  */
 691 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 692 {
 693         int try,retval=0;
 694         struct linux_binfmt *fmt;
 695 #ifdef __alpha__
 696         /* handle /sbin/loader.. */
 697         {
 698             struct exec * eh = (struct exec *) bprm->buf;
 699             struct linux_binprm bprm_loader;
 700
 701             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
 702                 (eh->fh.f_flags & 0x3000) == 0x3000)
 703             {
 704                 int i;
 705                 char * dynloader[] = { "/sbin/loader" };
 706                 struct dentry * dentry;
 707
 708                 dput(bprm->dentry);
 709                 bprm->dentry = NULL;
 710
 711                 bprm_loader.p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
 712                 for (i=0 ; i<MAX_ARG_PAGES ; i++)       /* clear page-table */
 713                     bprm_loader.page[i] = 0;
 714
 715                 dentry = open_namei(dynloader[0], 0, 0);
 716                 retval = PTR_ERR(dentry);
 717                 if (IS_ERR(dentry))
 718                         return retval;
 719                 bprm->dentry = dentry;
 720                 bprm->loader = bprm_loader.p;
 721                 retval = prepare_binprm(bprm);
 722                 if (retval<0)
 723                         return retval;
 724                 /* should call search_binary_handler recursively here,
 725                    but it does not matter */
 726             }
 727         }
 728 #endif
 729         for (try=0; try<2; try++) {
 730                 for (fmt = formats ; fmt ; fmt = fmt->next) {
 731                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
 732                         if (!fn)
 733                                 continue;
 734                         retval = fn(bprm, regs);
 735                         if (retval >= 0) {
 736                                 if (bprm->dentry)
 737                                         dput(bprm->dentry);
 738                                 bprm->dentry = NULL;
 739                                 current->did_exec = 1;
 740                                 return retval;
 741                         }
 742                         if (retval != -ENOEXEC)
 743                                 break;
 744                         if (!bprm->dentry) /* We don't have the dentry anymore */
 745                                 return retval;
 746                 }
 747                 if (retval != -ENOEXEC) {
 748                         break;
 749 #ifdef CONFIG_KMOD
 750                 }else{
 751 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
 752                         char modname[20];
 753                         if (printable(bprm->buf[0]) &&
 754                             printable(bprm->buf[1]) &&
 755                             printable(bprm->buf[2]) &&
 756                             printable(bprm->buf[3]))
 757                                 break; /* -ENOEXEC */
 758                         sprintf(modname, "binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
 759                         request_module(modname);
 760 #endif
 761                 }
 762         }
 763         return retval;
 764 }
 765
 766
 767 /*
 768  * sys_execve() executes a new program.
 769  */
 770 int do_execve(char * filename, char ** argv, char ** envp, struct pt_regs * regs)
 771 {
 772         struct linux_binprm bprm;
 773         struct dentry * dentry;
 774         int retval;
 775         int i;
 776
 777         bprm.p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
 778         memset(bprm.page, 0, MAX_ARG_PAGES*sizeof(bprm.page[0]));
 779
 780         dentry = open_namei(filename, 0, 0);
 781         retval = PTR_ERR(dentry);
 782         if (IS_ERR(dentry))
 783                 return retval;
 784
 785         bprm.dentry = dentry;
 786         bprm.filename = filename;
 787         bprm.sh_bang = 0;
 788         bprm.loader = 0;
 789         bprm.exec = 0;
 790         if ((bprm.argc = count(argv)) < 0) {
 791                 dput(dentry);
 792                 return bprm.argc;
 793         }
 794
 795         if ((bprm.envc = count(envp)) < 0) {
 796                 dput(dentry);
 797                 return bprm.envc;
 798         }
 799
 800         retval = prepare_binprm(&bprm);
 801         if (retval < 0)
 802                 goto out;
 803
 804         retval = copy_strings_kernel(1, &bprm.filename, &bprm);
 805         if (retval < 0)
 806                 goto out;
 807
 808         bprm.exec = bprm.p;
 809         retval = copy_strings(bprm.envc, envp, &bprm);
 810         if (retval < 0)
 811                 goto out;
 812
 813         retval = copy_strings(bprm.argc, argv, &bprm);
 814         if (retval < 0)
 815                 goto out;
 816
 817         retval = search_binary_handler(&bprm,regs);
 818         if (retval >= 0)
 819                 /* execve success */
 820                 return retval;
 821
 822 out:
 823         /* Something went wrong, return the inode and free the argument pages*/
 824         if (bprm.dentry)
 825                 dput(bprm.dentry);
 826
 827         /* Assumes that free_page() can take a NULL argument. */
 828         /* I hope this is ok for all architectures */
 829         for (i=0 ; i<MAX_ARG_PAGES ; i++)
 830                 free_page(bprm.page[i]);
 831
 832         return retval;
 833 }
 834
 835 int do_coredump(long signr, struct pt_regs * regs)
 836 {
 837         struct linux_binfmt * binfmt;
 838         char corename[6+sizeof(current->comm)];
 839         struct file * file;
 840         struct dentry * dentry;
 841         struct inode * inode;
 842
 843         lock_kernel();
 844         binfmt = current->binfmt;
 845         if (!binfmt || !binfmt->core_dump)
 846                 goto fail;
 847         if (!current->dumpable || atomic_read(&current->mm->mm_users) != 1)
 848         current->dumpable = 0;
 849         if (current->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
 850                 goto fail;
 851
 852         memcpy(corename,"core.", 5);
 853 #if 0
 854         memcpy(corename+5,current->comm,sizeof(current->comm));
 855 #else
 856         corename[4] = '\0';
 857 #endif
 858         file = filp_open(corename, O_CREAT | 2 | O_TRUNC | O_NOFOLLOW, 0600);
 859         if (IS_ERR(file))
 860                 goto fail;
 861         dentry = file->f_dentry;
 862         inode = dentry->d_inode;
 863         if (inode->i_nlink > 1)
 864                 goto close_fail;        /* multiple links - don't dump */
 865
 866         if (!S_ISREG(inode->i_mode))
 867                 goto close_fail;
 868         if (!inode->i_op || !inode->i_op->default_file_ops)
 869                 goto close_fail;
 870         if (!file->f_op->write)
 871                 goto close_fail;
 872         if (!binfmt->core_dump(signr, regs, file))
 873                 goto close_fail;
 874         filp_close(file, NULL);
 875         unlock_kernel();
 876         return 1;
 877
 878 close_fail:
 879         filp_close(file, NULL);
 880 fail:
 881         unlock_kernel();
 882         return 0;
 883 }