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_memory.h>
  28
  29 #include <asm/system.h>
  30 #include <asm/uaccess.h>
  31 #include <asm/cacheflush.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);
  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)
  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 = (void *)(((unsigned long)(&dump.regs)) - ((unsigned long)(&dump)));
 120 #endif
 121         dump.signal = signr;
 122         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) >
 128             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 129                 dump.u_dsize = 0;
 130 #else
 131         if ((dump.u_dsize+dump.u_ssize+1) * PAGE_SIZE >
 132             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 133                 dump.u_dsize = 0;
 134 #endif
 135
 136 /* Make sure we have enough room to write the stack and data areas. */
 137 #ifdef __sparc__
 138         if ((dump.u_ssize) >
 139             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 140                 dump.u_ssize = 0;
 141 #else
 142         if ((dump.u_ssize+1) * PAGE_SIZE >
 143             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 144                 dump.u_ssize = 0;
 145 #endif
 146
 147 /* make sure we actually have a data and stack area to dump */
 148         set_fs(USER_DS);
 149 #ifdef __sparc__
 150         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize))
 151                 dump.u_dsize = 0;
 152         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize))
 153                 dump.u_ssize = 0;
 154 #else
 155         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
 156                 dump.u_dsize = 0;
 157         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
 158                 dump.u_ssize = 0;
 159 #endif
 160
 161         set_fs(KERNEL_DS);
 162 /* struct user */
 163         DUMP_WRITE(&dump,sizeof(dump));
 164 /* Now dump all of the user data.  Include malloced stuff as well */
 165 #ifndef __sparc__
 166         DUMP_SEEK(PAGE_SIZE);
 167 #endif
 168 /* now we start writing out the user space info */
 169         set_fs(USER_DS);
 170 /* Dump the data area */
 171         if (dump.u_dsize != 0) {
 172                 dump_start = START_DATA(dump);
 173 #ifdef __sparc__
 174                 dump_size = dump.u_dsize;
 175 #else
 176                 dump_size = dump.u_dsize << PAGE_SHIFT;
 177 #endif
 178                 DUMP_WRITE(dump_start,dump_size);
 179         }
 180 /* Now prepare to dump the stack area */
 181         if (dump.u_ssize != 0) {
 182                 dump_start = START_STACK(dump);
 183 #ifdef __sparc__
 184                 dump_size = dump.u_ssize;
 185 #else
 186                 dump_size = dump.u_ssize << PAGE_SHIFT;
 187 #endif
 188                 DUMP_WRITE(dump_start,dump_size);
 189         }
 190 /* Finally dump the task struct.  Not be used by gdb, but could be useful */
 191         set_fs(KERNEL_DS);
 192         DUMP_WRITE(current,sizeof(*current));
 193 end_coredump:
 194         set_fs(fs);
 195         return has_dumped;
 196 }
 197
 198 /*
 199  * create_aout_tables() parses the env- and arg-strings in new user
 200  * memory and creates the pointer tables from them, and puts their
 201  * addresses on the "stack", returning the new stack pointer value.
 202  */
 203 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
 204 {
 205         char __user * __user *argv;
 206         char __user * __user *envp;
 207         unsigned long __user *sp;
 208         int argc = bprm->argc;
 209         int envc = bprm->envc;
 210
 211         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
 212 #ifdef __sparc__
 213         /* This imposes the proper stack alignment for a new process. */
 214         sp = (void __user *) (((unsigned long) sp) & ~7);
 215         if ((envc+argc+3)&1) --sp;
 216 #endif
 217 #ifdef __alpha__
 218 /* whee.. test-programs are so much fun. */
 219         put_user(0, --sp);
 220         put_user(0, --sp);
 221         if (bprm->loader) {
 222                 put_user(0, --sp);
 223                 put_user(0x3eb, --sp);
 224                 put_user(bprm->loader, --sp);
 225                 put_user(0x3ea, --sp);
 226         }
 227         put_user(bprm->exec, --sp);
 228         put_user(0x3e9, --sp);
 229 #endif
 230         sp -= envc+1;
 231         envp = (char __user * __user *) sp;
 232         sp -= argc+1;
 233         argv = (char __user * __user *) sp;
 234 #if defined(__i386__) || defined(__mc68000__) || defined(__arm__) || defined(__arch_um__)
 235         put_user((unsigned long) envp,--sp);
 236         put_user((unsigned long) argv,--sp);
 237 #endif
 238         put_user(argc,--sp);
 239         current->mm->arg_start = (unsigned long) p;
 240         while (argc-->0) {
 241                 char c;
 242                 put_user(p,argv++);
 243                 do {
 244                         get_user(c,p++);
 245                 } while (c);
 246         }
 247         put_user(NULL,argv);
 248         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 249         while (envc-->0) {
 250                 char c;
 251                 put_user(p,envp++);
 252                 do {
 253                         get_user(c,p++);
 254                 } while (c);
 255         }
 256         put_user(NULL,envp);
 257         current->mm->env_end = (unsigned long) p;
 258         return sp;
 259 }
 260
 261 /*
 262  * These are the functions used to load a.out style executables and shared
 263  * libraries.  There is no binary dependent code anywhere else.
 264  */
 265
 266 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 267 {
 268         struct exec ex;
 269         unsigned long error;
 270         unsigned long fd_offset;
 271         unsigned long rlim;
 272         int retval;
 273
 274         ex = *((struct exec *) bprm->buf);              /* exec-header */
 275         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 276              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 277             N_TRSIZE(ex) || N_DRSIZE(ex) ||
 278             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 279                 return -ENOEXEC;
 280         }
 281
 282         /*
 283          * Requires a mmap handler. This prevents people from using a.out
 284          * as part of an exploit attack against /proc-related vulnerabilities.
 285          */
 286         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
 287                 return -ENOEXEC;
 288
 289         fd_offset = N_TXTOFF(ex);
 290
 291         /* Check initial limits. This avoids letting people circumvent
 292          * size limits imposed on them by creating programs with large
 293          * arrays in the data or bss.
 294          */
 295         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
 296         if (rlim >= RLIM_INFINITY)
 297                 rlim = ~0;
 298         if (ex.a_data + ex.a_bss > rlim)
 299                 return -ENOMEM;
 300
 301         /* Flush all traces of the currently running executable */
 302         retval = flush_old_exec(bprm);
 303         if (retval)
 304                 return retval;
 305
 306         /* OK, This is the point of no return */
 307 #if defined(__alpha__)
 308         SET_AOUT_PERSONALITY(bprm, ex);
 309 #elif defined(__sparc__)
 310         set_personality(PER_SUNOS);
 311 #if !defined(__sparc_v9__)
 312         memcpy(&current->thread.core_exec, &ex, sizeof(struct exec));
 313 #endif
 314 #else
 315         set_personality(PER_LINUX);
 316 #endif
 317
 318         current->mm->end_code = ex.a_text +
 319                 (current->mm->start_code = N_TXTADDR(ex));
 320         current->mm->end_data = ex.a_data +
 321                 (current->mm->start_data = N_DATADDR(ex));
 322         current->mm->brk = ex.a_bss +
 323                 (current->mm->start_brk = N_BSSADDR(ex));
 324         current->mm->free_area_cache = current->mm->mmap_base;
 325         current->mm->cached_hole_size = 0;
 326
 327         current->mm->mmap = NULL;
 328         compute_creds(bprm);
 329         current->flags &= ~PF_FORKNOEXEC;
 330 #ifdef __sparc__
 331         if (N_MAGIC(ex) == NMAGIC) {
 332                 loff_t pos = fd_offset;
 333                 /* Fuck me plenty... */
 334                 /* <AOL></AOL> */
 335                 down_write(&current->mm->mmap_sem);
 336                 error = do_brk(N_TXTADDR(ex), ex.a_text);
 337                 up_write(&current->mm->mmap_sem);
 338                 bprm->file->f_op->read(bprm->file, (char *) N_TXTADDR(ex),
 339                           ex.a_text, &pos);
 340                 down_write(&current->mm->mmap_sem);
 341                 error = do_brk(N_DATADDR(ex), ex.a_data);
 342                 up_write(&current->mm->mmap_sem);
 343                 bprm->file->f_op->read(bprm->file, (char *) N_DATADDR(ex),
 344                           ex.a_data, &pos);
 345                 goto beyond_if;
 346         }
 347 #endif
 348
 349         if (N_MAGIC(ex) == OMAGIC) {
 350                 unsigned long text_addr, map_size;
 351                 loff_t pos;
 352
 353                 text_addr = N_TXTADDR(ex);
 354
 355 #if defined(__alpha__) || defined(__sparc__)
 356                 pos = fd_offset;
 357                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 358 #else
 359                 pos = 32;
 360                 map_size = ex.a_text+ex.a_data;
 361 #endif
 362                 down_write(&current->mm->mmap_sem);
 363                 error = do_brk(text_addr & PAGE_MASK, map_size);
 364                 up_write(&current->mm->mmap_sem);
 365                 if (error != (text_addr & PAGE_MASK)) {
 366                         send_sig(SIGKILL, current, 0);
 367                         return error;
 368                 }
 369
 370                 error = bprm->file->f_op->read(bprm->file,
 371                           (char __user *)text_addr,
 372                           ex.a_text+ex.a_data, &pos);
 373                 if ((signed long)error < 0) {
 374                         send_sig(SIGKILL, current, 0);
 375                         return error;
 376                 }
 377
 378                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
 379         } else {
 380                 static unsigned long error_time, error_time2;
 381                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 382                     (N_MAGIC(ex) != NMAGIC) && (jiffies-error_time2) > 5*HZ)
 383                 {
 384                         printk(KERN_NOTICE "executable not page aligned\n");
 385                         error_time2 = jiffies;
 386                 }
 387
 388                 if ((fd_offset & ~PAGE_MASK) != 0 &&
 389                     (jiffies-error_time) > 5*HZ)
 390                 {
 391                         printk(KERN_WARNING
 392                                "fd_offset is not page aligned. Please convert program: %s\n",
 393                                bprm->file->f_path.dentry->d_name.name);
 394                         error_time = jiffies;
 395                 }
 396
 397                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 398                         loff_t pos = fd_offset;
 399                         down_write(&current->mm->mmap_sem);
 400                         do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 401                         up_write(&current->mm->mmap_sem);
 402                         bprm->file->f_op->read(bprm->file,
 403                                         (char __user *)N_TXTADDR(ex),
 404                                         ex.a_text+ex.a_data, &pos);
 405                         flush_icache_range((unsigned long) N_TXTADDR(ex),
 406                                            (unsigned long) N_TXTADDR(ex) +
 407                                            ex.a_text+ex.a_data);
 408                         goto beyond_if;
 409                 }
 410
 411                 down_write(&current->mm->mmap_sem);
 412                 error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 413                         PROT_READ | PROT_EXEC,
 414                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 415                         fd_offset);
 416                 up_write(&current->mm->mmap_sem);
 417
 418                 if (error != N_TXTADDR(ex)) {
 419                         send_sig(SIGKILL, current, 0);
 420                         return error;
 421                 }
 422
 423                 down_write(&current->mm->mmap_sem);
 424                 error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 425                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 426                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 427                                 fd_offset + ex.a_text);
 428                 up_write(&current->mm->mmap_sem);
 429                 if (error != N_DATADDR(ex)) {
 430                         send_sig(SIGKILL, current, 0);
 431                         return error;
 432                 }
 433         }
 434 beyond_if:
 435         set_binfmt(&aout_format);
 436
 437         retval = set_brk(current->mm->start_brk, current->mm->brk);
 438         if (retval < 0) {
 439                 send_sig(SIGKILL, current, 0);
 440                 return retval;
 441         }
 442
 443         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 444         if (retval < 0) {
 445                 /* Someone check-me: is this error path enough? */
 446                 send_sig(SIGKILL, current, 0);
 447                 return retval;
 448         }
 449
 450         current->mm->start_stack =
 451                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 452 #ifdef __alpha__
 453         regs->gp = ex.a_gpvalue;
 454 #endif
 455         start_thread(regs, ex.a_entry, current->mm->start_stack);
 456         return 0;
 457 }
 458
 459 static int load_aout_library(struct file *file)
 460 {
 461         struct inode * inode;
 462         unsigned long bss, start_addr, len;
 463         unsigned long error;
 464         int retval;
 465         struct exec ex;
 466
 467         inode = file->f_path.dentry->d_inode;
 468
 469         retval = -ENOEXEC;
 470         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 471         if (error != sizeof(ex))
 472                 goto out;
 473
 474         /* We come in here for the regular a.out style of shared libraries */
 475         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 476             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 477             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 478                 goto out;
 479         }
 480
 481         /*
 482          * Requires a mmap handler. This prevents people from using a.out
 483          * as part of an exploit attack against /proc-related vulnerabilities.
 484          */
 485         if (!file->f_op || !file->f_op->mmap)
 486                 goto out;
 487
 488         if (N_FLAGS(ex))
 489                 goto out;
 490
 491         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 492            this off to get the starting address for the page */
 493
 494         start_addr =  ex.a_entry & 0xfffff000;
 495
 496         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 497                 static unsigned long error_time;
 498                 loff_t pos = N_TXTOFF(ex);
 499
 500                 if ((jiffies-error_time) > 5*HZ)
 501                 {
 502                         printk(KERN_WARNING
 503                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
 504                                file->f_path.dentry->d_name.name);
 505                         error_time = jiffies;
 506                 }
 507                 down_write(&current->mm->mmap_sem);
 508                 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 509                 up_write(&current->mm->mmap_sem);
 510
 511                 file->f_op->read(file, (char __user *)start_addr,
 512                         ex.a_text + ex.a_data, &pos);
 513                 flush_icache_range((unsigned long) start_addr,
 514                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
 515
 516                 retval = 0;
 517                 goto out;
 518         }
 519         /* Now use mmap to map the library into memory. */
 520         down_write(&current->mm->mmap_sem);
 521         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
 522                         PROT_READ | PROT_WRITE | PROT_EXEC,
 523                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 524                         N_TXTOFF(ex));
 525         up_write(&current->mm->mmap_sem);
 526         retval = error;
 527         if (error != start_addr)
 528                 goto out;
 529
 530         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 531         bss = ex.a_text + ex.a_data + ex.a_bss;
 532         if (bss > len) {
 533                 down_write(&current->mm->mmap_sem);
 534                 error = do_brk(start_addr + len, bss - len);
 535                 up_write(&current->mm->mmap_sem);
 536                 retval = error;
 537                 if (error != start_addr + len)
 538                         goto out;
 539         }
 540         retval = 0;
 541 out:
 542         return retval;
 543 }
 544
 545 static int __init init_aout_binfmt(void)
 546 {
 547         return register_binfmt(&aout_format);
 548 }
 549
 550 static void __exit exit_aout_binfmt(void)
 551 {
 552         unregister_binfmt(&aout_format);
 553 }
 554
 555 core_initcall(init_aout_binfmt);
 556 module_exit(exit_aout_binfmt);
 557 MODULE_LICENSE("GPL");