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