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