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

DEFINITIONS
