fs/binfmt_aout.c

   1 /*
   2  *  linux/fs/binfmt_aout.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
   5  */
   6
   7 #include <linux/module.h>
   8
   9 #include <linux/time.h>
  10 #include <linux/kernel.h>
  11 #include <linux/mm.h>
  12 #include <linux/mman.h>
  13 #include <linux/a.out.h>
  14 #include <linux/errno.h>
  15 #include <linux/signal.h>
  16 #include <linux/string.h>
  17 #include <linux/fs.h>
  18 #include <linux/file.h>
  19 #include <linux/stat.h>
  20 #include <linux/fcntl.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/user.h>
  23 #include <linux/slab.h>
  24 #include <linux/binfmts.h>
  25 #include <linux/personality.h>
  26 #include <linux/init.h>
  27 #include <linux/vs_base.h>
  28 #include <linux/vs_memory.h>
  29
  30 #include <asm/system.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/cacheflush.h>
  33
  34 static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
  35 static int load_aout_library(struct file*);
  36 static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file);
  37
  38 static struct linux_binfmt aout_format = {
  39         .module         = THIS_MODULE,
  40         .load_binary    = load_aout_binary,
  41         .load_shlib     = load_aout_library,
  42         .core_dump      = aout_core_dump,
  43         .min_coredump   = PAGE_SIZE
  44 };
  45
  46 #define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
  47
  48 static int set_brk(unsigned long start, unsigned long end)
  49 {
  50         start = PAGE_ALIGN(start);
  51         end = PAGE_ALIGN(end);
  52         if (end > start) {
  53                 unsigned long addr;
  54                 down_write(&current->mm->mmap_sem);
  55                 addr = do_brk(start, end - start);
  56                 up_write(&current->mm->mmap_sem);
  57                 if (BAD_ADDR(addr))
  58                         return addr;
  59         }
  60         return 0;
  61 }
  62
  63 /*
  64  * These are the only things you should do on a core-file: use only these
  65  * macros to write out all the necessary info.
  66  */
  67
  68 static int dump_write(struct file *file, const void *addr, int nr)
  69 {
  70         return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
  71 }
  72
  73 #define DUMP_WRITE(addr, nr)    \
  74         if (!dump_write(file, (void *)(addr), (nr))) \
  75                 goto end_coredump;
  76
  77 #define DUMP_SEEK(offset) \
  78 if (file->f_op->llseek) { \
  79         if (file->f_op->llseek(file,(offset),0) != (offset)) \
  80                 goto end_coredump; \
  81 } else file->f_pos = (offset)
  82
  83 /*
  84  * Routine writes a core dump image in the current directory.
  85  * Currently only a stub-function.
  86  *
  87  * Note that setuid/setgid files won't make a core-dump if the uid/gid
  88  * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
  89  * field, which also makes sure the core-dumps won't be recursive if the
  90  * dumping of the process results in another error..
  91  */
  92
  93 static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file)
  94 {
  95         mm_segment_t fs;
  96         int has_dumped = 0;
  97         unsigned long dump_start, dump_size;
  98         struct user dump;
  99 #if defined(__alpha__)
 100 #       define START_DATA(u)    (u.start_data)
 101 #elif defined(__arm__)
 102 #       define START_DATA(u)    ((u.u_tsize << PAGE_SHIFT) + u.start_code)
 103 #elif defined(__sparc__)
 104 #       define START_DATA(u)    (u.u_tsize)
 105 #elif defined(__i386__) || defined(__mc68000__) || defined(__arch_um__)
 106 #       define START_DATA(u)    (u.u_tsize << PAGE_SHIFT)
 107 #endif
 108 #ifdef __sparc__
 109 #       define START_STACK(u)   ((regs->u_regs[UREG_FP]) & ~(PAGE_SIZE - 1))
 110 #else
 111 #       define START_STACK(u)   (u.start_stack)
 112 #endif
 113
 114         fs = get_fs();
 115         set_fs(KERNEL_DS);
 116         has_dumped = 1;
 117         current->flags |= PF_DUMPCORE;
 118         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
 119 #ifndef __sparc__
 120         dump.u_ar0 = (void *)(((unsigned long)(&dump.regs)) - ((unsigned long)(&dump)));
 121 #endif
 122         dump.signal = signr;
 123         dump_thread(regs, &dump);
 124
 125 /* If the size of the dump file exceeds the rlimit, then see what would happen
 126    if we wrote the stack, but not the data area.  */
 127 #ifdef __sparc__
 128         if ((dump.u_dsize+dump.u_ssize) >
 129             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 130                 dump.u_dsize = 0;
 131 #else
 132         if ((dump.u_dsize+dump.u_ssize+1) * PAGE_SIZE >
 133             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 134                 dump.u_dsize = 0;
 135 #endif
 136
 137 /* Make sure we have enough room to write the stack and data areas. */
 138 #ifdef __sparc__
 139         if ((dump.u_ssize) >
 140             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 141                 dump.u_ssize = 0;
 142 #else
 143         if ((dump.u_ssize+1) * PAGE_SIZE >
 144             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 145                 dump.u_ssize = 0;
 146 #endif
 147
 148 /* make sure we actually have a data and stack area to dump */
 149         set_fs(USER_DS);
 150 #ifdef __sparc__
 151         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize))
 152                 dump.u_dsize = 0;
 153         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize))
 154                 dump.u_ssize = 0;
 155 #else
 156         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
 157                 dump.u_dsize = 0;
 158         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
 159                 dump.u_ssize = 0;
 160 #endif
 161
 162         set_fs(KERNEL_DS);
 163 /* struct user */
 164         DUMP_WRITE(&dump,sizeof(dump));
 165 /* Now dump all of the user data.  Include malloced stuff as well */
 166 #ifndef __sparc__
 167         DUMP_SEEK(PAGE_SIZE);
 168 #endif
 169 /* now we start writing out the user space info */
 170         set_fs(USER_DS);
 171 /* Dump the data area */
 172         if (dump.u_dsize != 0) {
 173                 dump_start = START_DATA(dump);
 174 #ifdef __sparc__
 175                 dump_size = dump.u_dsize;
 176 #else
 177                 dump_size = dump.u_dsize << PAGE_SHIFT;
 178 #endif
 179                 DUMP_WRITE(dump_start,dump_size);
 180         }
 181 /* Now prepare to dump the stack area */
 182         if (dump.u_ssize != 0) {
 183                 dump_start = START_STACK(dump);
 184 #ifdef __sparc__
 185                 dump_size = dump.u_ssize;
 186 #else
 187                 dump_size = dump.u_ssize << PAGE_SHIFT;
 188 #endif
 189                 DUMP_WRITE(dump_start,dump_size);
 190         }
 191 /* Finally dump the task struct.  Not be used by gdb, but could be useful */
 192         set_fs(KERNEL_DS);
 193         DUMP_WRITE(current,sizeof(*current));
 194 end_coredump:
 195         set_fs(fs);
 196         return has_dumped;
 197 }
 198
 199 /*
 200  * create_aout_tables() parses the env- and arg-strings in new user
 201  * memory and creates the pointer tables from them, and puts their
 202  * addresses on the "stack", returning the new stack pointer value.
 203  */
 204 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
 205 {
 206         char __user * __user *argv;
 207         char __user * __user *envp;
 208         unsigned long __user *sp;
 209         int argc = bprm->argc;
 210         int envc = bprm->envc;
 211
 212         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
 213 #ifdef __sparc__
 214         /* This imposes the proper stack alignment for a new process. */
 215         sp = (void __user *) (((unsigned long) sp) & ~7);
 216         if ((envc+argc+3)&1) --sp;
 217 #endif
 218 #ifdef __alpha__
 219 /* whee.. test-programs are so much fun. */
 220         put_user(0, --sp);
 221         put_user(0, --sp);
 222         if (bprm->loader) {
 223                 put_user(0, --sp);
 224                 put_user(0x3eb, --sp);
 225                 put_user(bprm->loader, --sp);
 226                 put_user(0x3ea, --sp);
 227         }
 228         put_user(bprm->exec, --sp);
 229         put_user(0x3e9, --sp);
 230 #endif
 231         sp -= envc+1;
 232         envp = (char __user * __user *) sp;
 233         sp -= argc+1;
 234         argv = (char __user * __user *) sp;
 235 #if defined(__i386__) || defined(__mc68000__) || defined(__arm__) || defined(__arch_um__)
 236         put_user((unsigned long) envp,--sp);
 237         put_user((unsigned long) argv,--sp);
 238 #endif
 239         put_user(argc,--sp);
 240         current->mm->arg_start = (unsigned long) p;
 241         while (argc-->0) {
 242                 char c;
 243                 put_user(p,argv++);
 244                 do {
 245                         get_user(c,p++);
 246                 } while (c);
 247         }
 248         put_user(NULL,argv);
 249         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 250         while (envc-->0) {
 251                 char c;
 252                 put_user(p,envp++);
 253                 do {
 254                         get_user(c,p++);
 255                 } while (c);
 256         }
 257         put_user(NULL,envp);
 258         current->mm->env_end = (unsigned long) p;
 259         return sp;
 260 }
 261
 262 /*
 263  * These are the functions used to load a.out style executables and shared
 264  * libraries.  There is no binary dependent code anywhere else.
 265  */
 266
 267 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 268 {
 269         struct exec ex;
 270         unsigned long error;
 271         unsigned long fd_offset;
 272         unsigned long rlim;
 273         int retval;
 274
 275         ex = *((struct exec *) bprm->buf);              /* exec-header */
 276         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 277              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 278             N_TRSIZE(ex) || N_DRSIZE(ex) ||
 279             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 280                 return -ENOEXEC;
 281         }
 282
 283         /*
 284          * Requires a mmap handler. This prevents people from using a.out
 285          * as part of an exploit attack against /proc-related vulnerabilities.
 286          */
 287         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
 288                 return -ENOEXEC;
 289
 290         fd_offset = N_TXTOFF(ex);
 291
 292         /* Check initial limits. This avoids letting people circumvent
 293          * size limits imposed on them by creating programs with large
 294          * arrays in the data or bss.
 295          */
 296         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
 297         if (rlim >= RLIM_INFINITY)
 298                 rlim = ~0;
 299         if (ex.a_data + ex.a_bss > rlim)
 300                 return -ENOMEM;
 301
 302         /* Flush all traces of the currently running executable */
 303         retval = flush_old_exec(bprm);
 304         if (retval)
 305                 return retval;
 306
 307         /* OK, This is the point of no return */
 308 #if defined(__alpha__)
 309         SET_AOUT_PERSONALITY(bprm, ex);
 310 #elif defined(__sparc__)
 311         set_personality(PER_SUNOS);
 312 #if !defined(__sparc_v9__)
 313         memcpy(&current->thread.core_exec, &ex, sizeof(struct exec));
 314 #endif
 315 #else
 316         set_personality(PER_LINUX);
 317 #endif
 318
 319         current->mm->end_code = ex.a_text +
 320                 (current->mm->start_code = N_TXTADDR(ex));
 321         current->mm->end_data = ex.a_data +
 322                 (current->mm->start_data = N_DATADDR(ex));
 323         current->mm->brk = ex.a_bss +
 324                 (current->mm->start_brk = N_BSSADDR(ex));
 325         current->mm->free_area_cache = current->mm->mmap_base;
 326         current->mm->cached_hole_size = 0;
 327
 328         current->mm->mmap = NULL;
 329         compute_creds(bprm);
 330         current->flags &= ~PF_FORKNOEXEC;
 331 #ifdef __sparc__
 332         if (N_MAGIC(ex) == NMAGIC) {
 333                 loff_t pos = fd_offset;
 334                 /* Fuck me plenty... */
 335                 /* <AOL></AOL> */
 336                 down_write(&current->mm->mmap_sem);
 337                 error = do_brk(N_TXTADDR(ex), ex.a_text);
 338                 up_write(&current->mm->mmap_sem);
 339                 bprm->file->f_op->read(bprm->file, (char *) N_TXTADDR(ex),
 340                           ex.a_text, &pos);
 341                 down_write(&current->mm->mmap_sem);
 342                 error = do_brk(N_DATADDR(ex), ex.a_data);
 343                 up_write(&current->mm->mmap_sem);
 344                 bprm->file->f_op->read(bprm->file, (char *) N_DATADDR(ex),
 345                           ex.a_data, &pos);
 346                 goto beyond_if;
 347         }
 348 #endif
 349
 350         if (N_MAGIC(ex) == OMAGIC) {
 351                 unsigned long text_addr, map_size;
 352                 loff_t pos;
 353
 354                 text_addr = N_TXTADDR(ex);
 355
 356 #if defined(__alpha__) || defined(__sparc__)
 357                 pos = fd_offset;
 358                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 359 #else
 360                 pos = 32;
 361                 map_size = ex.a_text+ex.a_data;
 362 #endif
 363                 down_write(&current->mm->mmap_sem);
 364                 error = do_brk(text_addr & PAGE_MASK, map_size);
 365                 up_write(&current->mm->mmap_sem);
 366                 if (error != (text_addr & PAGE_MASK)) {
 367                         send_sig(SIGKILL, current, 0);
 368                         return error;
 369                 }
 370
 371                 error = bprm->file->f_op->read(bprm->file,
 372                           (char __user *)text_addr,
 373                           ex.a_text+ex.a_data, &pos);
 374                 if ((signed long)error < 0) {
 375                         send_sig(SIGKILL, current, 0);
 376                         return error;
 377                 }
 378
 379                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
 380         } else {
 381                 static unsigned long error_time, error_time2;
 382                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 383                     (N_MAGIC(ex) != NMAGIC) && (jiffies-error_time2) > 5*HZ)
 384                 {
 385                         printk(KERN_NOTICE "executable not page aligned\n");
 386                         error_time2 = jiffies;
 387                 }
 388
 389                 if ((fd_offset & ~PAGE_MASK) != 0 &&
 390                     (jiffies-error_time) > 5*HZ)
 391                 {
 392                         printk(KERN_WARNING
 393                                "fd_offset is not page aligned. Please convert program: %s\n",
 394                                bprm->file->f_path.dentry->d_name.name);
 395                         error_time = jiffies;
 396                 }
 397
 398                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 399                         loff_t pos = fd_offset;
 400                         down_write(&current->mm->mmap_sem);
 401                         do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 402                         up_write(&current->mm->mmap_sem);
 403                         bprm->file->f_op->read(bprm->file,
 404                                         (char __user *)N_TXTADDR(ex),
 405                                         ex.a_text+ex.a_data, &pos);
 406                         flush_icache_range((unsigned long) N_TXTADDR(ex),
 407                                            (unsigned long) N_TXTADDR(ex) +
 408                                            ex.a_text+ex.a_data);
 409                         goto beyond_if;
 410                 }
 411
 412                 down_write(&current->mm->mmap_sem);
 413                 error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 414                         PROT_READ | PROT_EXEC,
 415                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 416                         fd_offset);
 417                 up_write(&current->mm->mmap_sem);
 418
 419                 if (error != N_TXTADDR(ex)) {
 420                         send_sig(SIGKILL, current, 0);
 421                         return error;
 422                 }
 423
 424                 down_write(&current->mm->mmap_sem);
 425                 error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 426                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 427                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 428                                 fd_offset + ex.a_text);
 429                 up_write(&current->mm->mmap_sem);
 430                 if (error != N_DATADDR(ex)) {
 431                         send_sig(SIGKILL, current, 0);
 432                         return error;
 433                 }
 434         }
 435 beyond_if:
 436         set_binfmt(&aout_format);
 437
 438         retval = set_brk(current->mm->start_brk, current->mm->brk);
 439         if (retval < 0) {
 440                 send_sig(SIGKILL, current, 0);
 441                 return retval;
 442         }
 443
 444         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 445         if (retval < 0) {
 446                 /* Someone check-me: is this error path enough? */
 447                 send_sig(SIGKILL, current, 0);
 448                 return retval;
 449         }
 450
 451         current->mm->start_stack =
 452                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 453 #ifdef __alpha__
 454         regs->gp = ex.a_gpvalue;
 455 #endif
 456         start_thread(regs, ex.a_entry, current->mm->start_stack);
 457         return 0;
 458 }
 459
 460 static int load_aout_library(struct file *file)
 461 {
 462         struct inode * inode;
 463         unsigned long bss, start_addr, len;
 464         unsigned long error;
 465         int retval;
 466         struct exec ex;
 467
 468         inode = file->f_path.dentry->d_inode;
 469
 470         retval = -ENOEXEC;
 471         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 472         if (error != sizeof(ex))
 473                 goto out;
 474
 475         /* We come in here for the regular a.out style of shared libraries */
 476         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 477             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 478             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 479                 goto out;
 480         }
 481
 482         /*
 483          * Requires a mmap handler. This prevents people from using a.out
 484          * as part of an exploit attack against /proc-related vulnerabilities.
 485          */
 486         if (!file->f_op || !file->f_op->mmap)
 487                 goto out;
 488
 489         if (N_FLAGS(ex))
 490                 goto out;
 491
 492         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 493            this off to get the starting address for the page */
 494
 495         start_addr =  ex.a_entry & 0xfffff000;
 496
 497         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 498                 static unsigned long error_time;
 499                 loff_t pos = N_TXTOFF(ex);
 500
 501                 if ((jiffies-error_time) > 5*HZ)
 502                 {
 503                         printk(KERN_WARNING
 504                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
 505                                file->f_path.dentry->d_name.name);
 506                         error_time = jiffies;
 507                 }
 508                 down_write(&current->mm->mmap_sem);
 509                 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 510                 up_write(&current->mm->mmap_sem);
 511
 512                 file->f_op->read(file, (char __user *)start_addr,
 513                         ex.a_text + ex.a_data, &pos);
 514                 flush_icache_range((unsigned long) start_addr,
 515                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
 516
 517                 retval = 0;
 518                 goto out;
 519         }
 520         /* Now use mmap to map the library into memory. */
 521         down_write(&current->mm->mmap_sem);
 522         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
 523                         PROT_READ | PROT_WRITE | PROT_EXEC,
 524                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 525                         N_TXTOFF(ex));
 526         up_write(&current->mm->mmap_sem);
 527         retval = error;
 528         if (error != start_addr)
 529                 goto out;
 530
 531         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 532         bss = ex.a_text + ex.a_data + ex.a_bss;
 533         if (bss > len) {
 534                 down_write(&current->mm->mmap_sem);
 535                 error = do_brk(start_addr + len, bss - len);
 536                 up_write(&current->mm->mmap_sem);
 537                 retval = error;
 538                 if (error != start_addr + len)
 539                         goto out;
 540         }
 541         retval = 0;
 542 out:
 543         return retval;
 544 }
 545
 546 static int __init init_aout_binfmt(void)
 547 {
 548         return register_binfmt(&aout_format);
 549 }
 550
 551 static void __exit exit_aout_binfmt(void)
 552 {
 553         unregister_binfmt(&aout_format);
 554 }
 555
 556 core_initcall(init_aout_binfmt);
 557 module_exit(exit_aout_binfmt);
 558 MODULE_LICENSE("GPL");