fs/exec.c

/* */
This source file includes following definitions.
register_binfmt
unregister_binfmt
open_inode
aout_core_dump
sys_uselib
create_tables
count
copy_strings
change_ldt
read_exec
flush_old_exec
do_execve
sys_execve
set_brk
load_aout_binary
load_aout_library
   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 /*
  12  * Demand-loading implemented 01.12.91 - no need to read anything but
  13  * the header into memory. The inode of the executable is put into
  14  * "current->executable", and page faults do the actual loading. Clean.
  15  *
  16  * Once more I can proudly say that linux stood up to being changed: it
  17  * was less than 2 hours work to get demand-loading completely implemented.
  18  *
  19  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  20  * current->executable is only used by the procfs.  This allows a dispatch
  21  * table to check for several different types  of binary formats.  We keep
  22  * trying until we recognize the file or we run out of supported binary
  23  * formats. 
  24  */
  25 
  26 #include <linux/fs.h>
  27 #include <linux/sched.h>
  28 #include <linux/kernel.h>
  29 #include <linux/mm.h>
  30 #include <linux/mman.h>
  31 #include <linux/a.out.h>
  32 #include <linux/errno.h>
  33 #include <linux/signal.h>
  34 #include <linux/string.h>
  35 #include <linux/stat.h>
  36 #include <linux/fcntl.h>
  37 #include <linux/ptrace.h>
  38 #include <linux/user.h>
  39 #include <linux/segment.h>
  40 #include <linux/malloc.h>
  41 
  42 #include <asm/system.h>
  43 
  44 #include <linux/binfmts.h>
  45 #include <linux/personality.h>
  46 
  47 #include <asm/segment.h>
  48 #include <asm/system.h>
  49 
  50 asmlinkage int sys_exit(int exit_code);
  51 asmlinkage int sys_brk(unsigned long);
  52 
  53 static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
  54 static int load_aout_library(int fd);
  55 static int aout_core_dump(long signr, struct pt_regs * regs);
  56 
  57 /*
  58  * Here are the actual binaries that will be accepted:
  59  * add more with "register_binfmt()"..
  60  */
  61 extern struct linux_binfmt elf_format;
  62 
  63 static struct linux_binfmt aout_format = {
  64 #ifndef CONFIG_BINFMT_ELF
  65         NULL, NULL, load_aout_binary, load_aout_library, aout_core_dump
  66 #else
  67         &elf_format, NULL, load_aout_binary, load_aout_library, aout_core_dump
  68 #endif
  69 };
  70 
  71 static struct linux_binfmt *formats = &aout_format;
  72 
  73 int register_binfmt(struct linux_binfmt * fmt)
     /*  */
  74 {
  75         struct linux_binfmt ** tmp = &formats;
  76 
  77         if (!fmt)
  78                 return -EINVAL;
  79         if (fmt->next)
  80                 return -EBUSY;
  81         while (*tmp) {
  82                 if (fmt == *tmp)
  83                         return -EBUSY;
  84                 tmp = &(*tmp)->next;
  85         }
  86         *tmp = fmt;
  87         return 0;       
  88 }
  89 
  90 int unregister_binfmt(struct linux_binfmt * fmt)
     /*  */
  91 {
  92         struct linux_binfmt ** tmp = &formats;
  93 
  94         while (*tmp) {
  95                 if (fmt == *tmp) {
  96                         *tmp = fmt->next;
  97                         return 0;
  98                 }
  99                 tmp = &(*tmp)->next;
 100         }
 101         return -EINVAL;
 102 }
 103 
 104 int open_inode(struct inode * inode, int mode)
     /*  */
 105 {
 106         int error, fd;
 107         struct file *f, **fpp;
 108 
 109         if (!inode->i_op || !inode->i_op->default_file_ops)
 110                 return -EINVAL;
 111         f = get_empty_filp();
 112         if (!f)
 113                 return -EMFILE;
 114         fd = 0;
 115         fpp = current->files->fd;
 116         for (;;) {
 117                 if (!*fpp)
 118                         break;
 119                 if (++fd > NR_OPEN)
 120                         return -ENFILE;
 121                 fpp++;
 122         }
 123         *fpp = f;
 124         f->f_flags = mode;
 125         f->f_mode = (mode+1) & O_ACCMODE;
 126         f->f_inode = inode;
 127         f->f_pos = 0;
 128         f->f_reada = 0;
 129         f->f_op = inode->i_op->default_file_ops;
 130         if (f->f_op->open) {
 131                 error = f->f_op->open(inode,f);
 132                 if (error) {
 133                         *fpp = NULL;
 134                         f->f_count--;
 135                         return error;
 136                 }
 137         }
 138         inode->i_count++;
 139         return fd;
 140 }
 141 
 142 /*
 143  * These are the only things you should do on a core-file: use only these
 144  * macros to write out all the necessary info.
 145  */
 146 #define DUMP_WRITE(addr,nr) \
 147 while (file.f_op->write(inode,&file,(char *)(addr),(nr)) != (nr)) goto close_coredump
 148 
 149 #define DUMP_SEEK(offset) \
 150 if (file.f_op->lseek) { \
 151         if (file.f_op->lseek(inode,&file,(offset),0) != (offset)) \
 152                 goto close_coredump; \
 153 } else file.f_pos = (offset)            
 154 
 155 /*
 156  * Routine writes a core dump image in the current directory.
 157  * Currently only a stub-function.
 158  *
 159  * Note that setuid/setgid files won't make a core-dump if the uid/gid
 160  * changed due to the set[u|g]id. It's enforced by the "current->dumpable"
 161  * field, which also makes sure the core-dumps won't be recursive if the
 162  * dumping of the process results in another error..
 163  */
 164 static int aout_core_dump(long signr, struct pt_regs * regs)
     /*  */
 165 {
 166         struct inode * inode = NULL;
 167         struct file file;
 168         unsigned short fs;
 169         int has_dumped = 0;
 170         char corefile[6+sizeof(current->comm)];
 171         int i;
 172         register int dump_start, dump_size;
 173         struct user dump;
 174 
 175         if (!current->dumpable)
 176                 return 0;
 177         current->dumpable = 0;
 178 
 179 /* See if we have enough room to write the upage.  */
 180         if (current->rlim[RLIMIT_CORE].rlim_cur < PAGE_SIZE)
 181                 return 0;
 182         fs = get_fs();
 183         set_fs(KERNEL_DS);
 184         memcpy(corefile,"core.",5);
 185 #if 0
 186         memcpy(corefile+5,current->comm,sizeof(current->comm));
 187 #else
 188         corefile[4] = '\0';
 189 #endif
 190         if (open_namei(corefile,O_CREAT | 2 | O_TRUNC,0600,&inode,NULL)) {
 191                 inode = NULL;
 192                 goto end_coredump;
 193         }
 194         if (!S_ISREG(inode->i_mode))
 195                 goto end_coredump;
 196         if (!inode->i_op || !inode->i_op->default_file_ops)
 197                 goto end_coredump;
 198         if (get_write_access(inode))
 199                 goto end_coredump;
 200         file.f_mode = 3;
 201         file.f_flags = 0;
 202         file.f_count = 1;
 203         file.f_inode = inode;
 204         file.f_pos = 0;
 205         file.f_reada = 0;
 206         file.f_op = inode->i_op->default_file_ops;
 207         if (file.f_op->open)
 208                 if (file.f_op->open(inode,&file))
 209                         goto done_coredump;
 210         if (!file.f_op->write)
 211                 goto close_coredump;
 212         has_dumped = 1;
 213 /* changed the size calculations - should hopefully work better. lbt */
 214         dump.magic = CMAGIC;
 215         dump.start_code = 0;
 216         dump.start_stack = regs->esp & ~(PAGE_SIZE - 1);
 217         dump.u_tsize = ((unsigned long) current->mm->end_code) >> 12;
 218         dump.u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> 12;
 219         dump.u_dsize -= dump.u_tsize;
 220         dump.u_ssize = 0;
 221         for(i=0; i<8; i++) dump.u_debugreg[i] = current->debugreg[i];  
 222         if (dump.start_stack < TASK_SIZE)
 223                 dump.u_ssize = ((unsigned long) (TASK_SIZE - dump.start_stack)) >> 12;
 224 /* If the size of the dump file exceeds the rlimit, then see what would happen
 225    if we wrote the stack, but not the data area.  */
 226         if ((dump.u_dsize+dump.u_ssize+1) * PAGE_SIZE >
 227             current->rlim[RLIMIT_CORE].rlim_cur)
 228                 dump.u_dsize = 0;
 229 /* Make sure we have enough room to write the stack and data areas. */
 230         if ((dump.u_ssize+1) * PAGE_SIZE >
 231             current->rlim[RLIMIT_CORE].rlim_cur)
 232                 dump.u_ssize = 0;
 233         strncpy(dump.u_comm, current->comm, sizeof(current->comm));
 234         dump.u_ar0 = (struct pt_regs *)(((int)(&dump.regs)) -((int)(&dump)));
 235         dump.signal = signr;
 236         dump.regs = *regs;
 237 /* Flag indicating the math stuff is valid. We don't support this for the
 238    soft-float routines yet */
 239         if (hard_math) {
 240                 if ((dump.u_fpvalid = current->used_math) != 0) {
 241                         if (last_task_used_math == current)
 242                                 __asm__("clts ; fnsave %0": :"m" (dump.i387));
 243                         else
 244                                 memcpy(&dump.i387,&current->tss.i387.hard,sizeof(dump.i387));
 245                 }
 246         } else {
 247                 /* we should dump the emulator state here, but we need to
 248                    convert it into standard 387 format first.. */
 249                 dump.u_fpvalid = 0;
 250         }
 251         set_fs(KERNEL_DS);
 252 /* struct user */
 253         DUMP_WRITE(&dump,sizeof(dump));
 254 /* Now dump all of the user data.  Include malloced stuff as well */
 255         DUMP_SEEK(PAGE_SIZE);
 256 /* now we start writing out the user space info */
 257         set_fs(USER_DS);
 258 /* Dump the data area */
 259         if (dump.u_dsize != 0) {
 260                 dump_start = dump.u_tsize << 12;
 261                 dump_size = dump.u_dsize << 12;
 262                 DUMP_WRITE(dump_start,dump_size);
 263         }
 264 /* Now prepare to dump the stack area */
 265         if (dump.u_ssize != 0) {
 266                 dump_start = dump.start_stack;
 267                 dump_size = dump.u_ssize << 12;
 268                 DUMP_WRITE(dump_start,dump_size);
 269         }
 270 /* Finally dump the task struct.  Not be used by gdb, but could be useful */
 271         set_fs(KERNEL_DS);
 272         DUMP_WRITE(current,sizeof(*current));
 273 close_coredump:
 274         if (file.f_op->release)
 275                 file.f_op->release(inode,&file);
 276 done_coredump:
 277         put_write_access(inode);
 278 end_coredump:
 279         set_fs(fs);
 280         iput(inode);
 281         return has_dumped;
 282 }
 283 
 284 /*
 285  * Note that a shared library must be both readable and executable due to
 286  * security reasons.
 287  *
 288  * Also note that we take the address to load from from the file itself.
 289  */
 290 asmlinkage int sys_uselib(const char * library)
     /*  */
 291 {
 292         int fd, retval;
 293         struct file * file;
 294         struct linux_binfmt * fmt;
 295 
 296         fd = sys_open(library, 0, 0);
 297         if (fd < 0)
 298                 return fd;
 299         file = current->files->fd[fd];
 300         retval = -ENOEXEC;
 301         if (file && file->f_inode && file->f_op && file->f_op->read) {
 302                 for (fmt = formats ; fmt ; fmt = fmt->next) {
 303                         int (*fn)(int) = fmt->load_shlib;
 304                         if (!fn)
 305                                 break;
 306                         retval = fn(fd);
 307                         if (retval != -ENOEXEC)
 308                                 break;
 309                 }
 310         }
 311         sys_close(fd);
 312         return retval;
 313 }
 314 
 315 /*
 316  * create_tables() parses the env- and arg-strings in new user
 317  * memory and creates the pointer tables from them, and puts their
 318  * addresses on the "stack", returning the new stack pointer value.
 319  */
 320 unsigned long * create_tables(char * p,int argc,int envc,int ibcs)
     /*  */
 321 {
 322         unsigned long *argv,*envp;
 323         unsigned long * sp;
 324         struct vm_area_struct *mpnt;
 325 
 326         mpnt = (struct vm_area_struct *)kmalloc(sizeof(*mpnt), GFP_KERNEL);
 327         if (mpnt) {
 328                 mpnt->vm_task = current;
 329                 mpnt->vm_start = PAGE_MASK & (unsigned long) p;
 330                 mpnt->vm_end = TASK_SIZE;
 331                 mpnt->vm_page_prot = PAGE_PRIVATE|PAGE_DIRTY;
 332                 mpnt->vm_flags = VM_STACK_FLAGS;
 333                 mpnt->vm_share = NULL;
 334                 mpnt->vm_ops = NULL;
 335                 mpnt->vm_offset = 0;
 336                 mpnt->vm_inode = NULL;
 337                 mpnt->vm_pte = 0;
 338                 insert_vm_struct(current, mpnt);
 339         }
 340         sp = (unsigned long *) (0xfffffffc & (unsigned long) p);
 341         sp -= envc+1;
 342         envp = sp;
 343         sp -= argc+1;
 344         argv = sp;
 345         if (!ibcs) {
 346                 put_fs_long((unsigned long)envp,--sp);
 347                 put_fs_long((unsigned long)argv,--sp);
 348         }
 349         put_fs_long((unsigned long)argc,--sp);
 350         current->mm->arg_start = (unsigned long) p;
 351         while (argc-->0) {
 352                 put_fs_long((unsigned long) p,argv++);
 353                 while (get_fs_byte(p++)) /* nothing */ ;
 354         }
 355         put_fs_long(0,argv);
 356         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 357         while (envc-->0) {
 358                 put_fs_long((unsigned long) p,envp++);
 359                 while (get_fs_byte(p++)) /* nothing */ ;
 360         }
 361         put_fs_long(0,envp);
 362         current->mm->env_end = (unsigned long) p;
 363         return sp;
 364 }
 365 
 366 /*
 367  * count() counts the number of arguments/envelopes
 368  */
 369 static int count(char ** argv)
     /*  */
 370 {
 371         int i=0;
 372         char ** tmp;
 373 
 374         if ((tmp = argv) != 0)
 375                 while (get_fs_long((unsigned long *) (tmp++)))
 376                         i++;
 377 
 378         return i;
 379 }
 380 
 381 /*
 382  * 'copy_string()' copies argument/envelope strings from user
 383  * memory to free pages in kernel mem. These are in a format ready
 384  * to be put directly into the top of new user memory.
 385  *
 386  * Modified by TYT, 11/24/91 to add the from_kmem argument, which specifies
 387  * whether the string and the string array are from user or kernel segments:
 388  * 
 389  * from_kmem     argv *        argv **
 390  *    0          user space    user space
 391  *    1          kernel space  user space
 392  *    2          kernel space  kernel space
 393  * 
 394  * We do this by playing games with the fs segment register.  Since it
 395  * is expensive to load a segment register, we try to avoid calling
 396  * set_fs() unless we absolutely have to.
 397  */
 398 unsigned long copy_strings(int argc,char ** argv,unsigned long *page,
     /*  */
 399                 unsigned long p, int from_kmem)
 400 {
 401         char *tmp, *pag = NULL;
 402         int len, offset = 0;
 403         unsigned long old_fs, new_fs;
 404 
 405         if (!p)
 406                 return 0;       /* bullet-proofing */
 407         new_fs = get_ds();
 408         old_fs = get_fs();
 409         if (from_kmem==2)
 410                 set_fs(new_fs);
 411         while (argc-- > 0) {
 412                 if (from_kmem == 1)
 413                         set_fs(new_fs);
 414                 if (!(tmp = (char *)get_fs_long(((unsigned long *)argv)+argc)))
 415                         panic("VFS: argc is wrong");
 416                 if (from_kmem == 1)
 417                         set_fs(old_fs);
 418                 len=0;          /* remember zero-padding */
 419                 do {
 420                         len++;
 421                 } while (get_fs_byte(tmp++));
 422                 if (p < len) {  /* this shouldn't happen - 128kB */
 423                         set_fs(old_fs);
 424                         return 0;
 425                 }
 426                 while (len) {
 427                         --p; --tmp; --len;
 428                         if (--offset < 0) {
 429                                 offset = p % PAGE_SIZE;
 430                                 if (from_kmem==2)
 431                                         set_fs(old_fs);
 432                                 if (!(pag = (char *) page[p/PAGE_SIZE]) &&
 433                                     !(pag = (char *) page[p/PAGE_SIZE] =
 434                                       (unsigned long *) get_free_page(GFP_USER))) 
 435                                         return 0;
 436                                 if (from_kmem==2)
 437                                         set_fs(new_fs);
 438 
 439                         }
 440                         *(pag + offset) = get_fs_byte(tmp);
 441                 }
 442         }
 443         if (from_kmem==2)
 444                 set_fs(old_fs);
 445         return p;
 446 }
 447 
 448 unsigned long change_ldt(unsigned long text_size,unsigned long * page)
     /*  */
 449 {
 450         unsigned long code_limit,data_limit,code_base,data_base;
 451         int i;
 452 
 453         code_limit = TASK_SIZE;
 454         data_limit = TASK_SIZE;
 455         code_base = data_base = 0;
 456         current->mm->start_code = code_base;
 457         data_base += data_limit;
 458         for (i=MAX_ARG_PAGES-1 ; i>=0 ; i--) {
 459                 data_base -= PAGE_SIZE;
 460                 if (page[i]) {
 461                         current->mm->rss++;
 462                         put_dirty_page(current,page[i],data_base);
 463                 }
 464         }
 465         return data_limit;
 466 }
 467 
 468 /*
 469  * Read in the complete executable. This is used for "-N" files
 470  * that aren't on a block boundary, and for files on filesystems
 471  * without bmap support.
 472  */
 473 int read_exec(struct inode *inode, unsigned long offset,
     /*  */
 474         char * addr, unsigned long count)
 475 {
 476         struct file file;
 477         int result = -ENOEXEC;
 478 
 479         if (!inode->i_op || !inode->i_op->default_file_ops)
 480                 goto end_readexec;
 481         file.f_mode = 1;
 482         file.f_flags = 0;
 483         file.f_count = 1;
 484         file.f_inode = inode;
 485         file.f_pos = 0;
 486         file.f_reada = 0;
 487         file.f_op = inode->i_op->default_file_ops;
 488         if (file.f_op->open)
 489                 if (file.f_op->open(inode,&file))
 490                         goto end_readexec;
 491         if (!file.f_op || !file.f_op->read)
 492                 goto close_readexec;
 493         if (file.f_op->lseek) {
 494                 if (file.f_op->lseek(inode,&file,offset,0) != offset)
 495                         goto close_readexec;
 496         } else
 497                 file.f_pos = offset;
 498         if (get_fs() == USER_DS) {
 499                 result = verify_area(VERIFY_WRITE, addr, count);
 500                 if (result)
 501                         goto close_readexec;
 502         }
 503         result = file.f_op->read(inode, &file, addr, count);
 504 close_readexec:
 505         if (file.f_op->release)
 506                 file.f_op->release(inode,&file);
 507 end_readexec:
 508         return result;
 509 }
 510 
 511 
 512 /*
 513  * This function flushes out all traces of the currently running executable so
 514  * that a new one can be started
 515  */
 516 
 517 void flush_old_exec(struct linux_binprm * bprm)
     /*  */
 518 {
 519         int i;
 520         int ch;
 521         char * name;
 522         struct vm_area_struct * mpnt, *mpnt1;
 523 
 524         current->dumpable = 1;
 525         name = bprm->filename;
 526         for (i=0; (ch = *(name++)) != '\0';) {
 527                 if (ch == '/')
 528                         i = 0;
 529                 else
 530                         if (i < 15)
 531                                 current->comm[i++] = ch;
 532         }
 533         current->comm[i] = '\0';
 534         /* Release all of the old mmap stuff. */
 535 
 536         mpnt = current->mm->mmap;
 537         current->mm->mmap = NULL;
 538         while (mpnt) {
 539                 mpnt1 = mpnt->vm_next;
 540                 if (mpnt->vm_ops && mpnt->vm_ops->close)
 541                         mpnt->vm_ops->close(mpnt);
 542                 if (mpnt->vm_inode)
 543                         iput(mpnt->vm_inode);
 544                 kfree(mpnt);
 545                 mpnt = mpnt1;
 546         }
 547 
 548         /* Flush the old ldt stuff... */
 549         if (current->ldt) {
 550                 free_page((unsigned long) current->ldt);
 551                 current->ldt = NULL;
 552                 for (i=1 ; i<NR_TASKS ; i++) {
 553                         if (task[i] == current)  {
 554                                 set_ldt_desc(gdt+(i<<1)+
 555                                              FIRST_LDT_ENTRY,&default_ldt, 1);
 556                                 load_ldt(i);
 557                         }
 558                 }       
 559         }
 560 
 561         for (i=0 ; i<8 ; i++) current->debugreg[i] = 0;
 562 
 563         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
 564             !permission(bprm->inode,MAY_READ))
 565                 current->dumpable = 0;
 566         current->signal = 0;
 567         for (i=0 ; i<32 ; i++) {
 568                 current->sigaction[i].sa_mask = 0;
 569                 current->sigaction[i].sa_flags = 0;
 570                 if (current->sigaction[i].sa_handler != SIG_IGN)
 571                         current->sigaction[i].sa_handler = NULL;
 572         }
 573         for (i=0 ; i<NR_OPEN ; i++)
 574                 if (FD_ISSET(i,&current->files->close_on_exec))
 575                         sys_close(i);
 576         FD_ZERO(&current->files->close_on_exec);
 577         clear_page_tables(current);
 578         if (last_task_used_math == current)
 579                 last_task_used_math = NULL;
 580         current->used_math = 0;
 581 }
 582 
 583 /*
 584  * sys_execve() executes a new program.
 585  */
 586 int do_execve(char * filename, char ** argv, char ** envp, struct pt_regs * regs)
     /*  */
 587 {
 588         struct linux_binprm bprm;
 589         struct linux_binfmt * fmt;
 590         unsigned long old_fs;
 591         int i;
 592         int retval;
 593         int sh_bang = 0;
 594 
 595         if (regs->cs != USER_CS)
 596                 return -EINVAL;
 597         bprm.p = PAGE_SIZE*MAX_ARG_PAGES-4;
 598         for (i=0 ; i<MAX_ARG_PAGES ; i++)       /* clear page-table */
 599                 bprm.page[i] = 0;
 600         retval = open_namei(filename, 0, 0, &bprm.inode, NULL);
 601         if (retval)
 602                 return retval;
 603         bprm.filename = filename;
 604         bprm.argc = count(argv);
 605         bprm.envc = count(envp);
 606         
 607 restart_interp:
 608         if (!S_ISREG(bprm.inode->i_mode)) {     /* must be regular file */
 609                 retval = -EACCES;
 610                 goto exec_error2;
 611         }
 612         if (IS_NOEXEC(bprm.inode)) {            /* FS mustn't be mounted noexec */
 613                 retval = -EPERM;
 614                 goto exec_error2;
 615         }
 616         if (!bprm.inode->i_sb) {
 617                 retval = -EACCES;
 618                 goto exec_error2;
 619         }
 620         i = bprm.inode->i_mode;
 621         if (IS_NOSUID(bprm.inode) && (((i & S_ISUID) && bprm.inode->i_uid != current->
 622             euid) || ((i & S_ISGID) && !in_group_p(bprm.inode->i_gid))) && !suser()) {
 623                 retval = -EPERM;
 624                 goto exec_error2;
 625         }
 626         /* make sure we don't let suid, sgid files be ptraced. */
 627         if (current->flags & PF_PTRACED) {
 628                 bprm.e_uid = current->euid;
 629                 bprm.e_gid = current->egid;
 630         } else {
 631                 bprm.e_uid = (i & S_ISUID) ? bprm.inode->i_uid : current->euid;
 632                 bprm.e_gid = (i & S_ISGID) ? bprm.inode->i_gid : current->egid;
 633         }
 634         if (!permission(bprm.inode, MAY_EXEC) ||
 635             (!(bprm.inode->i_mode & 0111) && fsuser())) {
 636                 retval = -EACCES;
 637                 goto exec_error2;
 638         }
 639         /* better not execute files which are being written to */
 640         if (bprm.inode->i_wcount > 0) {
 641                 retval = -ETXTBSY;
 642                 goto exec_error2;
 643         }
 644         memset(bprm.buf,0,sizeof(bprm.buf));
 645         old_fs = get_fs();
 646         set_fs(get_ds());
 647         retval = read_exec(bprm.inode,0,bprm.buf,128);
 648         set_fs(old_fs);
 649         if (retval < 0)
 650                 goto exec_error2;
 651         if ((bprm.buf[0] == '#') && (bprm.buf[1] == '!') && (!sh_bang)) {
 652                 /*
 653                  * This section does the #! interpretation.
 654                  * Sorta complicated, but hopefully it will work.  -TYT
 655                  */
 656 
 657                 char *cp, *interp, *i_name, *i_arg;
 658 
 659                 iput(bprm.inode);
 660                 bprm.buf[127] = '\0';
 661                 if ((cp = strchr(bprm.buf, '\n')) == NULL)
 662                         cp = bprm.buf+127;
 663                 *cp = '\0';
 664                 while (cp > bprm.buf) {
 665                         cp--;
 666                         if ((*cp == ' ') || (*cp == '\t'))
 667                                 *cp = '\0';
 668                         else
 669                                 break;
 670                 }
 671                 for (cp = bprm.buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
 672                 if (!cp || *cp == '\0') {
 673                         retval = -ENOEXEC; /* No interpreter name found */
 674                         goto exec_error1;
 675                 }
 676                 interp = i_name = cp;
 677                 i_arg = 0;
 678                 for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++) {
 679                         if (*cp == '/')
 680                                 i_name = cp+1;
 681                 }
 682                 while ((*cp == ' ') || (*cp == '\t'))
 683                         *cp++ = '\0';
 684                 if (*cp)
 685                         i_arg = cp;
 686                 /*
 687                  * OK, we've parsed out the interpreter name and
 688                  * (optional) argument.
 689                  */
 690                 if (sh_bang++ == 0) {
 691                         bprm.p = copy_strings(bprm.envc, envp, bprm.page, bprm.p, 0);
 692                         bprm.p = copy_strings(--bprm.argc, argv+1, bprm.page, bprm.p, 0);
 693                 }
 694                 /*
 695                  * Splice in (1) the interpreter's name for argv[0]
 696                  *           (2) (optional) argument to interpreter
 697                  *           (3) filename of shell script
 698                  *
 699                  * This is done in reverse order, because of how the
 700                  * user environment and arguments are stored.
 701                  */
 702                 bprm.p = copy_strings(1, &bprm.filename, bprm.page, bprm.p, 2);
 703                 bprm.argc++;
 704                 if (i_arg) {
 705                         bprm.p = copy_strings(1, &i_arg, bprm.page, bprm.p, 2);
 706                         bprm.argc++;
 707                 }
 708                 bprm.p = copy_strings(1, &i_name, bprm.page, bprm.p, 2);
 709                 bprm.argc++;
 710                 if (!bprm.p) {
 711                         retval = -E2BIG;
 712                         goto exec_error1;
 713                 }
 714                 /*
 715                  * OK, now restart the process with the interpreter's inode.
 716                  * Note that we use open_namei() as the name is now in kernel
 717                  * space, and we don't need to copy it.
 718                  */
 719                 retval = open_namei(interp, 0, 0, &bprm.inode, NULL);
 720                 if (retval)
 721                         goto exec_error1;
 722                 goto restart_interp;
 723         }
 724         if (!sh_bang) {
 725                 bprm.p = copy_strings(bprm.envc,envp,bprm.page,bprm.p,0);
 726                 bprm.p = copy_strings(bprm.argc,argv,bprm.page,bprm.p,0);
 727                 if (!bprm.p) {
 728                         retval = -E2BIG;
 729                         goto exec_error2;
 730                 }
 731         }
 732 
 733         bprm.sh_bang = sh_bang;
 734         for (fmt = formats ; fmt ; fmt = fmt->next) {
 735                 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
 736                 if (!fn)
 737                         break;
 738                 retval = fn(&bprm, regs);
 739                 if (retval >= 0) {
 740                         iput(bprm.inode);
 741                         current->did_exec = 1;
 742                         return retval;
 743                 }
 744                 if (retval != -ENOEXEC)
 745                         break;
 746         }
 747 exec_error2:
 748         iput(bprm.inode);
 749 exec_error1:
 750         for (i=0 ; i<MAX_ARG_PAGES ; i++)
 751                 free_page(bprm.page[i]);
 752         return(retval);
 753 }
 754 
 755 /*
 756  * sys_execve() executes a new program.
 757  */
 758 asmlinkage int sys_execve(struct pt_regs regs)
     /*  */
 759 {
 760         int error;
 761         char * filename;
 762 
 763         error = getname((char *) regs.ebx, &filename);
 764         if (error)
 765                 return error;
 766         error = do_execve(filename, (char **) regs.ecx, (char **) regs.edx, &regs);
 767         putname(filename);
 768         return error;
 769 }
 770 
 771 static void set_brk(unsigned long start, unsigned long end)
     /*  */
 772 {
 773         start = PAGE_ALIGN(start);
 774         end = PAGE_ALIGN(end);
 775         if (end <= start)
 776                 return;
 777         do_mmap(NULL, start, end - start,
 778                 PROT_READ | PROT_WRITE | PROT_EXEC,
 779                 MAP_FIXED | MAP_PRIVATE, 0);
 780 }
 781 
 782 /*
 783  * These are the functions used to load a.out style executables and shared
 784  * libraries.  There is no binary dependent code anywhere else.
 785  */
 786 
 787 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
     /*  */
 788 {
 789         struct exec ex;
 790         struct file * file;
 791         int fd, error;
 792         unsigned long p = bprm->p;
 793         unsigned long fd_offset;
 794 
 795         ex = *((struct exec *) bprm->buf);              /* exec-header */
 796         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC && 
 797              N_MAGIC(ex) != QMAGIC) ||
 798             ex.a_trsize || ex.a_drsize ||
 799             bprm->inode->i_size < ex.a_text+ex.a_data+ex.a_syms+N_TXTOFF(ex)) {
 800                 return -ENOEXEC;
 801         }
 802 
 803         current->personality = PER_LINUX;
 804         fd_offset = N_TXTOFF(ex);
 805         if (N_MAGIC(ex) == ZMAGIC && fd_offset != BLOCK_SIZE) {
 806                 printk(KERN_NOTICE "N_TXTOFF != BLOCK_SIZE. See a.out.h.\n");
 807                 return -ENOEXEC;
 808         }
 809 
 810         if (N_MAGIC(ex) == ZMAGIC && ex.a_text &&
 811             (fd_offset < bprm->inode->i_sb->s_blocksize)) {
 812                 printk(KERN_NOTICE "N_TXTOFF < BLOCK_SIZE. Please convert binary.\n");
 813                 return -ENOEXEC;
 814         }
 815 
 816         /* OK, This is the point of no return */
 817         flush_old_exec(bprm);
 818 
 819         current->mm->brk = ex.a_bss +
 820                 (current->mm->start_brk =
 821                 (current->mm->end_data = ex.a_data +
 822                 (current->mm->end_code = ex.a_text +
 823                 (current->mm->start_code = N_TXTADDR(ex)))));
 824         current->mm->rss = 0;
 825         current->mm->mmap = NULL;
 826         current->suid = current->euid = current->fsuid = bprm->e_uid;
 827         current->sgid = current->egid = current->fsgid = bprm->e_gid;
 828         if (N_MAGIC(ex) == OMAGIC) {
 829                 do_mmap(NULL, 0, ex.a_text+ex.a_data,
 830                         PROT_READ|PROT_WRITE|PROT_EXEC,
 831                         MAP_FIXED|MAP_PRIVATE, 0);
 832                 read_exec(bprm->inode, 32, (char *) 0, ex.a_text+ex.a_data);
 833         } else {
 834                 if (ex.a_text & 0xfff || ex.a_data & 0xfff)
 835                         printk(KERN_NOTICE "executable not page aligned\n");
 836                 
 837                 fd = open_inode(bprm->inode, O_RDONLY);
 838                 
 839                 if (fd < 0)
 840                         return fd;
 841                 file = current->files->fd[fd];
 842                 if (!file->f_op || !file->f_op->mmap) {
 843                         sys_close(fd);
 844                         do_mmap(NULL, 0, ex.a_text+ex.a_data,
 845                                 PROT_READ|PROT_WRITE|PROT_EXEC,
 846                                 MAP_FIXED|MAP_PRIVATE, 0);
 847                         read_exec(bprm->inode, fd_offset,
 848                                   (char *) N_TXTADDR(ex), ex.a_text+ex.a_data);
 849                         goto beyond_if;
 850                 }
 851 
 852                 error = do_mmap(file, N_TXTADDR(ex), ex.a_text,
 853                         PROT_READ | PROT_EXEC,
 854                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 855                         fd_offset);
 856 
 857                 if (error != N_TXTADDR(ex)) {
 858                         sys_close(fd);
 859                         send_sig(SIGKILL, current, 0);
 860                         return error;
 861                 }
 862                 
 863                 error = do_mmap(file, N_TXTADDR(ex) + ex.a_text, ex.a_data,
 864                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 865                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 866                                 fd_offset + ex.a_text);
 867                 sys_close(fd);
 868                 if (error != N_TXTADDR(ex) + ex.a_text) {
 869                         send_sig(SIGKILL, current, 0);
 870                         return error;
 871                 }
 872         }
 873 beyond_if:
 874         if (current->exec_domain && current->exec_domain->use_count)
 875                 (*current->exec_domain->use_count)--;
 876         if (current->binfmt && current->binfmt->use_count)
 877                 (*current->binfmt->use_count)--;
 878         current->exec_domain = lookup_exec_domain(current->personality);
 879         current->binfmt = &aout_format;
 880         if (current->exec_domain && current->exec_domain->use_count)
 881                 (*current->exec_domain->use_count)++;
 882         if (current->binfmt && current->binfmt->use_count)
 883                 (*current->binfmt->use_count)++;
 884 
 885         set_brk(current->mm->start_brk, current->mm->brk);
 886         
 887         p += change_ldt(ex.a_text,bprm->page);
 888         p -= MAX_ARG_PAGES*PAGE_SIZE;
 889         p = (unsigned long)create_tables((char *)p,
 890                                         bprm->argc, bprm->envc,
 891                                         current->personality != PER_LINUX);
 892         current->mm->start_stack = p;
 893         regs->eip = ex.a_entry;         /* eip, magic happens :-) */
 894         regs->esp = p;                  /* stack pointer */
 895         if (current->flags & PF_PTRACED)
 896                 send_sig(SIGTRAP, current, 0);
 897         return 0;
 898 }
 899 
 900 
 901 static int load_aout_library(int fd)
     /*  */
 902 {
 903         struct file * file;
 904         struct exec ex;
 905         struct  inode * inode;
 906         unsigned int len;
 907         unsigned int bss;
 908         unsigned int start_addr;
 909         int error;
 910         
 911         file = current->files->fd[fd];
 912         inode = file->f_inode;
 913         
 914         set_fs(KERNEL_DS);
 915         if (file->f_op->read(inode, file, (char *) &ex, sizeof(ex)) != sizeof(ex)) {
 916                 return -EACCES;
 917         }
 918         set_fs(USER_DS);
 919         
 920         /* We come in here for the regular a.out style of shared libraries */
 921         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || ex.a_trsize ||
 922             ex.a_drsize || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 923             inode->i_size < ex.a_text+ex.a_data+ex.a_syms+N_TXTOFF(ex)) {
 924                 return -ENOEXEC;
 925         }
 926         if (N_MAGIC(ex) == ZMAGIC && N_TXTOFF(ex) && 
 927             (N_TXTOFF(ex) < inode->i_sb->s_blocksize)) {
 928                 printk("N_TXTOFF < BLOCK_SIZE. Please convert library\n");
 929                 return -ENOEXEC;
 930         }
 931         
 932         if (N_FLAGS(ex)) return -ENOEXEC;
 933 
 934         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 935            this off to get the starting address for the page */
 936 
 937         start_addr =  ex.a_entry & 0xfffff000;
 938 
 939         /* Now use mmap to map the library into memory. */
 940         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
 941                         PROT_READ | PROT_WRITE | PROT_EXEC,
 942                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 943                         N_TXTOFF(ex));
 944         if (error != start_addr)
 945                 return error;
 946         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 947         bss = ex.a_text + ex.a_data + ex.a_bss;
 948         if (bss > len)
 949                 do_mmap(NULL, start_addr + len, bss-len,
 950                         PROT_READ|PROT_WRITE|PROT_EXEC,
 951                         MAP_PRIVATE|MAP_FIXED, 0);
 952         return 0;
 953 }
/* */
root/fs/exec.c

DEFINITIONS
