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);
  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)
  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) >
 127             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 128                 dump.u_dsize = 0;
 129 #else
 130         if ((dump.u_dsize+dump.u_ssize+1) * PAGE_SIZE >
 131             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 132                 dump.u_dsize = 0;
 133 #endif
 134
 135 /* Make sure we have enough room to write the stack and data areas. */
 136 #ifdef __sparc__
 137         if ((dump.u_ssize) >
 138             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 139                 dump.u_ssize = 0;
 140 #else
 141         if ((dump.u_ssize+1) * PAGE_SIZE >
 142             current->signal->rlim[RLIMIT_CORE].rlim_cur)
 143                 dump.u_ssize = 0;
 144 #endif
 145
 146 /* make sure we actually have a data and stack area to dump */
 147         set_fs(USER_DS);
 148 #ifdef __sparc__
 149         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize))
 150                 dump.u_dsize = 0;
 151         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize))
 152                 dump.u_ssize = 0;
 153 #else
 154         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
 155                 dump.u_dsize = 0;
 156         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
 157                 dump.u_ssize = 0;
 158 #endif
 159
 160         set_fs(KERNEL_DS);
 161 /* struct user */
 162         DUMP_WRITE(&dump,sizeof(dump));
 163 /* Now dump all of the user data.  Include malloced stuff as well */
 164 #ifndef __sparc__
 165         DUMP_SEEK(PAGE_SIZE);
 166 #endif
 167 /* now we start writing out the user space info */
 168         set_fs(USER_DS);
 169 /* Dump the data area */
 170         if (dump.u_dsize != 0) {
 171                 dump_start = START_DATA(dump);
 172 #ifdef __sparc__
 173                 dump_size = dump.u_dsize;
 174 #else
 175                 dump_size = dump.u_dsize << PAGE_SHIFT;
 176 #endif
 177                 DUMP_WRITE(dump_start,dump_size);
 178         }
 179 /* Now prepare to dump the stack area */
 180         if (dump.u_ssize != 0) {
 181                 dump_start = START_STACK(dump);
 182 #ifdef __sparc__
 183                 dump_size = dump.u_ssize;
 184 #else
 185                 dump_size = dump.u_ssize << PAGE_SHIFT;
 186 #endif
 187                 DUMP_WRITE(dump_start,dump_size);
 188         }
 189 /* Finally dump the task struct.  Not be used by gdb, but could be useful */
 190         set_fs(KERNEL_DS);
 191         DUMP_WRITE(current,sizeof(*current));
 192 end_coredump:
 193         set_fs(fs);
 194         return has_dumped;
 195 }
 196
 197 /*
 198  * create_aout_tables() parses the env- and arg-strings in new user
 199  * memory and creates the pointer tables from them, and puts their
 200  * addresses on the "stack", returning the new stack pointer value.
 201  */
 202 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
 203 {
 204         char __user * __user *argv;
 205         char __user * __user *envp;
 206         unsigned long __user *sp;
 207         int argc = bprm->argc;
 208         int envc = bprm->envc;
 209
 210         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
 211 #ifdef __sparc__
 212         /* This imposes the proper stack alignment for a new process. */
 213         sp = (void __user *) (((unsigned long) sp) & ~7);
 214         if ((envc+argc+3)&1) --sp;
 215 #endif
 216 #ifdef __alpha__
 217 /* whee.. test-programs are so much fun. */
 218         put_user(0, --sp);
 219         put_user(0, --sp);
 220         if (bprm->loader) {
 221                 put_user(0, --sp);
 222                 put_user(0x3eb, --sp);
 223                 put_user(bprm->loader, --sp);
 224                 put_user(0x3ea, --sp);
 225         }
 226         put_user(bprm->exec, --sp);
 227         put_user(0x3e9, --sp);
 228 #endif
 229         sp -= envc+1;
 230         envp = (char __user * __user *) sp;
 231         sp -= argc+1;
 232         argv = (char __user * __user *) sp;
 233 #if defined(__i386__) || defined(__mc68000__) || defined(__arm__) || defined(__arch_um__)
 234         put_user((unsigned long) envp,--sp);
 235         put_user((unsigned long) argv,--sp);
 236 #endif
 237         put_user(argc,--sp);
 238         current->mm->arg_start = (unsigned long) p;
 239         while (argc-->0) {
 240                 char c;
 241                 put_user(p,argv++);
 242                 do {
 243                         get_user(c,p++);
 244                 } while (c);
 245         }
 246         put_user(NULL,argv);
 247         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 248         while (envc-->0) {
 249                 char c;
 250                 put_user(p,envp++);
 251                 do {
 252                         get_user(c,p++);
 253                 } while (c);
 254         }
 255         put_user(NULL,envp);
 256         current->mm->env_end = (unsigned long) p;
 257         return sp;
 258 }
 259
 260 /*
 261  * These are the functions used to load a.out style executables and shared
 262  * libraries.  There is no binary dependent code anywhere else.
 263  */
 264
 265 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 266 {
 267         struct exec ex;
 268         unsigned long error;
 269         unsigned long fd_offset;
 270         unsigned long rlim;
 271         int retval;
 272
 273         ex = *((struct exec *) bprm->buf);              /* exec-header */
 274         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 275              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 276             N_TRSIZE(ex) || N_DRSIZE(ex) ||
 277             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 278                 return -ENOEXEC;
 279         }
 280
 281         /*
 282          * Requires a mmap handler. This prevents people from using a.out
 283          * as part of an exploit attack against /proc-related vulnerabilities.
 284          */
 285         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
 286                 return -ENOEXEC;
 287
 288         fd_offset = N_TXTOFF(ex);
 289
 290         /* Check initial limits. This avoids letting people circumvent
 291          * size limits imposed on them by creating programs with large
 292          * arrays in the data or bss.
 293          */
 294         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
 295         if (rlim >= RLIM_INFINITY)
 296                 rlim = ~0;
 297         if (ex.a_data + ex.a_bss > rlim)
 298                 return -ENOMEM;
 299
 300         /* Flush all traces of the currently running executable */
 301         retval = flush_old_exec(bprm);
 302         if (retval)
 303                 return retval;
 304
 305         /* OK, This is the point of no return */
 306 #if defined(__alpha__)
 307         SET_AOUT_PERSONALITY(bprm, ex);
 308 #elif defined(__sparc__)
 309         set_personality(PER_SUNOS);
 310 #if !defined(__sparc_v9__)
 311         memcpy(&current->thread.core_exec, &ex, sizeof(struct exec));
 312 #endif
 313 #else
 314         set_personality(PER_LINUX);
 315 #endif
 316
 317         current->mm->end_code = ex.a_text +
 318                 (current->mm->start_code = N_TXTADDR(ex));
 319         current->mm->end_data = ex.a_data +
 320                 (current->mm->start_data = N_DATADDR(ex));
 321         current->mm->brk = ex.a_bss +
 322                 (current->mm->start_brk = N_BSSADDR(ex));
 323         current->mm->free_area_cache = current->mm->mmap_base;
 324         current->mm->cached_hole_size = 0;
 325
 326         current->mm->mmap = NULL;
 327         compute_creds(bprm);
 328         current->flags &= ~PF_FORKNOEXEC;
 329 #ifdef __sparc__
 330         if (N_MAGIC(ex) == NMAGIC) {
 331                 loff_t pos = fd_offset;
 332                 /* Fuck me plenty... */
 333                 /* <AOL></AOL> */
 334                 down_write(&current->mm->mmap_sem);
 335                 error = do_brk(N_TXTADDR(ex), ex.a_text);
 336                 up_write(&current->mm->mmap_sem);
 337                 bprm->file->f_op->read(bprm->file, (char *) N_TXTADDR(ex),
 338                           ex.a_text, &pos);
 339                 down_write(&current->mm->mmap_sem);
 340                 error = do_brk(N_DATADDR(ex), ex.a_data);
 341                 up_write(&current->mm->mmap_sem);
 342                 bprm->file->f_op->read(bprm->file, (char *) N_DATADDR(ex),
 343                           ex.a_data, &pos);
 344                 goto beyond_if;
 345         }
 346 #endif
 347
 348         if (N_MAGIC(ex) == OMAGIC) {
 349                 unsigned long text_addr, map_size;
 350                 loff_t pos;
 351
 352                 text_addr = N_TXTADDR(ex);
 353
 354 #if defined(__alpha__) || defined(__sparc__)
 355                 pos = fd_offset;
 356                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 357 #else
 358                 pos = 32;
 359                 map_size = ex.a_text+ex.a_data;
 360 #endif
 361                 down_write(&current->mm->mmap_sem);
 362                 error = do_brk(text_addr & PAGE_MASK, map_size);
 363                 up_write(&current->mm->mmap_sem);
 364                 if (error != (text_addr & PAGE_MASK)) {
 365                         send_sig(SIGKILL, current, 0);
 366                         return error;
 367                 }
 368
 369                 error = bprm->file->f_op->read(bprm->file,
 370                           (char __user *)text_addr,
 371                           ex.a_text+ex.a_data, &pos);
 372                 if ((signed long)error < 0) {
 373                         send_sig(SIGKILL, current, 0);
 374                         return error;
 375                 }
 376
 377                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
 378         } else {
 379                 static unsigned long error_time, error_time2;
 380                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 381                     (N_MAGIC(ex) != NMAGIC) && (jiffies-error_time2) > 5*HZ)
 382                 {
 383                         printk(KERN_NOTICE "executable not page aligned\n");
 384                         error_time2 = jiffies;
 385                 }
 386
 387                 if ((fd_offset & ~PAGE_MASK) != 0 &&
 388                     (jiffies-error_time) > 5*HZ)
 389                 {
 390                         printk(KERN_WARNING
 391                                "fd_offset is not page aligned. Please convert program: %s\n",
 392                                bprm->file->f_path.dentry->d_name.name);
 393                         error_time = jiffies;
 394                 }
 395
 396                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 397                         loff_t pos = fd_offset;
 398                         down_write(&current->mm->mmap_sem);
 399                         do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 400                         up_write(&current->mm->mmap_sem);
 401                         bprm->file->f_op->read(bprm->file,
 402                                         (char __user *)N_TXTADDR(ex),
 403                                         ex.a_text+ex.a_data, &pos);
 404                         flush_icache_range((unsigned long) N_TXTADDR(ex),
 405                                            (unsigned long) N_TXTADDR(ex) +
 406                                            ex.a_text+ex.a_data);
 407                         goto beyond_if;
 408                 }
 409
 410                 down_write(&current->mm->mmap_sem);
 411                 error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 412                         PROT_READ | PROT_EXEC,
 413                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 414                         fd_offset);
 415                 up_write(&current->mm->mmap_sem);
 416
 417                 if (error != N_TXTADDR(ex)) {
 418                         send_sig(SIGKILL, current, 0);
 419                         return error;
 420                 }
 421
 422                 down_write(&current->mm->mmap_sem);
 423                 error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 424                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 425                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 426                                 fd_offset + ex.a_text);
 427                 up_write(&current->mm->mmap_sem);
 428                 if (error != N_DATADDR(ex)) {
 429                         send_sig(SIGKILL, current, 0);
 430                         return error;
 431                 }
 432         }
 433 beyond_if:
 434         set_binfmt(&aout_format);
 435
 436         retval = set_brk(current->mm->start_brk, current->mm->brk);
 437         if (retval < 0) {
 438                 send_sig(SIGKILL, current, 0);
 439                 return retval;
 440         }
 441
 442         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 443         if (retval < 0) {
 444                 /* Someone check-me: is this error path enough? */
 445                 send_sig(SIGKILL, current, 0);
 446                 return retval;
 447         }
 448
 449         current->mm->start_stack =
 450                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 451 #ifdef __alpha__
 452         regs->gp = ex.a_gpvalue;
 453 #endif
 454         start_thread(regs, ex.a_entry, current->mm->start_stack);
 455         if (unlikely(current->ptrace & PT_PTRACED)) {
 456                 if (current->ptrace & PT_TRACE_EXEC)
 457                         ptrace_notify ((PTRACE_EVENT_EXEC << 8) | SIGTRAP);
 458                 else
 459                         send_sig(SIGTRAP, current, 0);
 460         }
 461         return 0;
 462 }
 463
 464 static int load_aout_library(struct file *file)
 465 {
 466         struct inode * inode;
 467         unsigned long bss, start_addr, len;
 468         unsigned long error;
 469         int retval;
 470         struct exec ex;
 471
 472         inode = file->f_path.dentry->d_inode;
 473
 474         retval = -ENOEXEC;
 475         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 476         if (error != sizeof(ex))
 477                 goto out;
 478
 479         /* We come in here for the regular a.out style of shared libraries */
 480         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 481             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 482             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 483                 goto out;
 484         }
 485
 486         /*
 487          * Requires a mmap handler. This prevents people from using a.out
 488          * as part of an exploit attack against /proc-related vulnerabilities.
 489          */
 490         if (!file->f_op || !file->f_op->mmap)
 491                 goto out;
 492
 493         if (N_FLAGS(ex))
 494                 goto out;
 495
 496         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 497            this off to get the starting address for the page */
 498
 499         start_addr =  ex.a_entry & 0xfffff000;
 500
 501         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 502                 static unsigned long error_time;
 503                 loff_t pos = N_TXTOFF(ex);
 504
 505                 if ((jiffies-error_time) > 5*HZ)
 506                 {
 507                         printk(KERN_WARNING
 508                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
 509                                file->f_path.dentry->d_name.name);
 510                         error_time = jiffies;
 511                 }
 512                 down_write(&current->mm->mmap_sem);
 513                 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 514                 up_write(&current->mm->mmap_sem);
 515
 516                 file->f_op->read(file, (char __user *)start_addr,
 517                         ex.a_text + ex.a_data, &pos);
 518                 flush_icache_range((unsigned long) start_addr,
 519                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
 520
 521                 retval = 0;
 522                 goto out;
 523         }
 524         /* Now use mmap to map the library into memory. */
 525         down_write(&current->mm->mmap_sem);
 526         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
 527                         PROT_READ | PROT_WRITE | PROT_EXEC,
 528                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 529                         N_TXTOFF(ex));
 530         up_write(&current->mm->mmap_sem);
 531         retval = error;
 532         if (error != start_addr)
 533                 goto out;
 534
 535         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 536         bss = ex.a_text + ex.a_data + ex.a_bss;
 537         if (bss > len) {
 538                 down_write(&current->mm->mmap_sem);
 539                 error = do_brk(start_addr + len, bss - len);
 540                 up_write(&current->mm->mmap_sem);
 541                 retval = error;
 542                 if (error != start_addr + len)
 543                         goto out;
 544         }
 545         retval = 0;
 546 out:
 547         return retval;
 548 }
 549
 550 static int __init init_aout_binfmt(void)
 551 {
 552         return register_binfmt(&aout_format);
 553 }
 554
 555 static void __exit exit_aout_binfmt(void)
 556 {
 557         unregister_binfmt(&aout_format);
 558 }
 559
 560 core_initcall(init_aout_binfmt);
 561 module_exit(exit_aout_binfmt);
 562 MODULE_LICENSE("GPL");