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