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 #ifdef __alpha__
  99 #       define START_DATA(u)    (u.start_data)
 100 #else
 101 #       define START_DATA(u)    ((u.u_tsize << PAGE_SHIFT) + u.start_code)
 102 #endif
 103 #       define START_STACK(u)   (u.start_stack)
 104
 105         fs = get_fs();
 106         set_fs(KERNEL_DS);
 107         has_dumped = 1;
 108         current->flags |= PF_DUMPCORE;
 109         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
 110         dump.u_ar0 = offsetof(struct user, regs);
 111         dump.signal = signr;
 112         aout_dump_thread(regs, &dump);
 113
 114 /* If the size of the dump file exceeds the rlimit, then see what would happen
 115    if we wrote the stack, but not the data area.  */
 116         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > limit)
 117                 dump.u_dsize = 0;
 118
 119 /* Make sure we have enough room to write the stack and data areas. */
 120         if ((dump.u_ssize + 1) * PAGE_SIZE > limit)
 121                 dump.u_ssize = 0;
 122
 123 /* make sure we actually have a data and stack area to dump */
 124         set_fs(USER_DS);
 125         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
 126                 dump.u_dsize = 0;
 127         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
 128                 dump.u_ssize = 0;
 129
 130         set_fs(KERNEL_DS);
 131 /* struct user */
 132         DUMP_WRITE(&dump,sizeof(dump));
 133 /* Now dump all of the user data.  Include malloced stuff as well */
 134         DUMP_SEEK(PAGE_SIZE);
 135 /* now we start writing out the user space info */
 136         set_fs(USER_DS);
 137 /* Dump the data area */
 138         if (dump.u_dsize != 0) {
 139                 dump_start = START_DATA(dump);
 140                 dump_size = dump.u_dsize << PAGE_SHIFT;
 141                 DUMP_WRITE(dump_start,dump_size);
 142         }
 143 /* Now prepare to dump the stack area */
 144         if (dump.u_ssize != 0) {
 145                 dump_start = START_STACK(dump);
 146                 dump_size = dump.u_ssize << PAGE_SHIFT;
 147                 DUMP_WRITE(dump_start,dump_size);
 148         }
 149 /* Finally dump the task struct.  Not be used by gdb, but could be useful */
 150         set_fs(KERNEL_DS);
 151         DUMP_WRITE(current,sizeof(*current));
 152 end_coredump:
 153         set_fs(fs);
 154         return has_dumped;
 155 }
 156
 157 /*
 158  * create_aout_tables() parses the env- and arg-strings in new user
 159  * memory and creates the pointer tables from them, and puts their
 160  * addresses on the "stack", returning the new stack pointer value.
 161  */
 162 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
 163 {
 164         char __user * __user *argv;
 165         char __user * __user *envp;
 166         unsigned long __user *sp;
 167         int argc = bprm->argc;
 168         int envc = bprm->envc;
 169
 170         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
 171 #ifdef __alpha__
 172 /* whee.. test-programs are so much fun. */
 173         put_user(0, --sp);
 174         put_user(0, --sp);
 175         if (bprm->loader) {
 176                 put_user(0, --sp);
 177                 put_user(1003, --sp);
 178                 put_user(bprm->loader, --sp);
 179                 put_user(1002, --sp);
 180         }
 181         put_user(bprm->exec, --sp);
 182         put_user(1001, --sp);
 183 #endif
 184         sp -= envc+1;
 185         envp = (char __user * __user *) sp;
 186         sp -= argc+1;
 187         argv = (char __user * __user *) sp;
 188 #ifndef __alpha__
 189         put_user((unsigned long) envp,--sp);
 190         put_user((unsigned long) argv,--sp);
 191 #endif
 192         put_user(argc,--sp);
 193         current->mm->arg_start = (unsigned long) p;
 194         while (argc-->0) {
 195                 char c;
 196                 put_user(p,argv++);
 197                 do {
 198                         get_user(c,p++);
 199                 } while (c);
 200         }
 201         put_user(NULL,argv);
 202         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 203         while (envc-->0) {
 204                 char c;
 205                 put_user(p,envp++);
 206                 do {
 207                         get_user(c,p++);
 208                 } while (c);
 209         }
 210         put_user(NULL,envp);
 211         current->mm->env_end = (unsigned long) p;
 212         return sp;
 213 }
 214
 215 /*
 216  * These are the functions used to load a.out style executables and shared
 217  * libraries.  There is no binary dependent code anywhere else.
 218  */
 219
 220 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 221 {
 222         struct exec ex;
 223         unsigned long error;
 224         unsigned long fd_offset;
 225         unsigned long rlim;
 226         int retval;
 227
 228         ex = *((struct exec *) bprm->buf);              /* exec-header */
 229         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 230              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 231             N_TRSIZE(ex) || N_DRSIZE(ex) ||
 232             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 233                 return -ENOEXEC;
 234         }
 235
 236         /*
 237          * Requires a mmap handler. This prevents people from using a.out
 238          * as part of an exploit attack against /proc-related vulnerabilities.
 239          */
 240         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
 241                 return -ENOEXEC;
 242
 243         fd_offset = N_TXTOFF(ex);
 244
 245         /* Check initial limits. This avoids letting people circumvent
 246          * size limits imposed on them by creating programs with large
 247          * arrays in the data or bss.
 248          */
 249         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
 250         if (rlim >= RLIM_INFINITY)
 251                 rlim = ~0;
 252         if (ex.a_data + ex.a_bss > rlim)
 253                 return -ENOMEM;
 254
 255         /* Flush all traces of the currently running executable */
 256         retval = flush_old_exec(bprm);
 257         if (retval)
 258                 return retval;
 259
 260         /* OK, This is the point of no return */
 261 #ifdef __alpha__
 262         SET_AOUT_PERSONALITY(bprm, ex);
 263 #else
 264         set_personality(PER_LINUX);
 265 #endif
 266
 267         current->mm->end_code = ex.a_text +
 268                 (current->mm->start_code = N_TXTADDR(ex));
 269         current->mm->end_data = ex.a_data +
 270                 (current->mm->start_data = N_DATADDR(ex));
 271         current->mm->brk = ex.a_bss +
 272                 (current->mm->start_brk = N_BSSADDR(ex));
 273         current->mm->free_area_cache = current->mm->mmap_base;
 274         current->mm->cached_hole_size = 0;
 275
 276         install_exec_creds(bprm);
 277         current->flags &= ~PF_FORKNOEXEC;
 278
 279         if (N_MAGIC(ex) == OMAGIC) {
 280                 unsigned long text_addr, map_size;
 281                 loff_t pos;
 282
 283                 text_addr = N_TXTADDR(ex);
 284
 285 #ifdef __alpha__
 286                 pos = fd_offset;
 287                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 288 #else
 289                 pos = 32;
 290                 map_size = ex.a_text+ex.a_data;
 291 #endif
 292                 down_write(&current->mm->mmap_sem);
 293                 error = do_brk(text_addr & PAGE_MASK, map_size);
 294                 up_write(&current->mm->mmap_sem);
 295                 if (error != (text_addr & PAGE_MASK)) {
 296                         send_sig(SIGKILL, current, 0);
 297                         return error;
 298                 }
 299
 300                 error = bprm->file->f_op->read(bprm->file,
 301                           (char __user *)text_addr,
 302                           ex.a_text+ex.a_data, &pos);
 303                 if ((signed long)error < 0) {
 304                         send_sig(SIGKILL, current, 0);
 305                         return error;
 306                 }
 307
 308                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
 309         } else {
 310                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 311                     (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
 312                 {
 313                         printk(KERN_NOTICE "executable not page aligned\n");
 314                 }
 315
 316                 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
 317                 {
 318                         printk(KERN_WARNING
 319                                "fd_offset is not page aligned. Please convert program: %s\n",
 320                                bprm->file->f_path.dentry->d_name.name);
 321                 }
 322
 323                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 324                         loff_t pos = fd_offset;
 325                         down_write(&current->mm->mmap_sem);
 326                         do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 327                         up_write(&current->mm->mmap_sem);
 328                         bprm->file->f_op->read(bprm->file,
 329                                         (char __user *)N_TXTADDR(ex),
 330                                         ex.a_text+ex.a_data, &pos);
 331                         flush_icache_range((unsigned long) N_TXTADDR(ex),
 332                                            (unsigned long) N_TXTADDR(ex) +
 333                                            ex.a_text+ex.a_data);
 334                         goto beyond_if;
 335                 }
 336
 337                 down_write(&current->mm->mmap_sem);
 338                 error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 339                         PROT_READ | PROT_EXEC,
 340                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 341                         fd_offset);
 342                 up_write(&current->mm->mmap_sem);
 343
 344                 if (error != N_TXTADDR(ex)) {
 345                         send_sig(SIGKILL, current, 0);
 346                         return error;
 347                 }
 348
 349                 down_write(&current->mm->mmap_sem);
 350                 error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 351                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 352                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 353                                 fd_offset + ex.a_text);
 354                 up_write(&current->mm->mmap_sem);
 355                 if (error != N_DATADDR(ex)) {
 356                         send_sig(SIGKILL, current, 0);
 357                         return error;
 358                 }
 359         }
 360 beyond_if:
 361         set_binfmt(&aout_format);
 362
 363         retval = set_brk(current->mm->start_brk, current->mm->brk);
 364         if (retval < 0) {
 365                 send_sig(SIGKILL, current, 0);
 366                 return retval;
 367         }
 368
 369         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 370         if (retval < 0) {
 371                 /* Someone check-me: is this error path enough? */
 372                 send_sig(SIGKILL, current, 0);
 373                 return retval;
 374         }
 375
 376         current->mm->start_stack =
 377                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 378 #ifdef __alpha__
 379         regs->gp = ex.a_gpvalue;
 380 #endif
 381         start_thread(regs, ex.a_entry, current->mm->start_stack);
 382         return 0;
 383 }
 384
 385 static int load_aout_library(struct file *file)
 386 {
 387         struct inode * inode;
 388         unsigned long bss, start_addr, len;
 389         unsigned long error;
 390         int retval;
 391         struct exec ex;
 392
 393         inode = file->f_path.dentry->d_inode;
 394
 395         retval = -ENOEXEC;
 396         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 397         if (error != sizeof(ex))
 398                 goto out;
 399
 400         /* We come in here for the regular a.out style of shared libraries */
 401         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 402             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 403             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 404                 goto out;
 405         }
 406
 407         /*
 408          * Requires a mmap handler. This prevents people from using a.out
 409          * as part of an exploit attack against /proc-related vulnerabilities.
 410          */
 411         if (!file->f_op || !file->f_op->mmap)
 412                 goto out;
 413
 414         if (N_FLAGS(ex))
 415                 goto out;
 416
 417         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 418            this off to get the starting address for the page */
 419
 420         start_addr =  ex.a_entry & 0xfffff000;
 421
 422         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 423                 loff_t pos = N_TXTOFF(ex);
 424
 425                 if (printk_ratelimit())
 426                 {
 427                         printk(KERN_WARNING
 428                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
 429                                file->f_path.dentry->d_name.name);
 430                 }
 431                 down_write(&current->mm->mmap_sem);
 432                 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 433                 up_write(&current->mm->mmap_sem);
 434
 435                 file->f_op->read(file, (char __user *)start_addr,
 436                         ex.a_text + ex.a_data, &pos);
 437                 flush_icache_range((unsigned long) start_addr,
 438                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
 439
 440                 retval = 0;
 441                 goto out;
 442         }
 443         /* Now use mmap to map the library into memory. */
 444         down_write(&current->mm->mmap_sem);
 445         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
 446                         PROT_READ | PROT_WRITE | PROT_EXEC,
 447                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 448                         N_TXTOFF(ex));
 449         up_write(&current->mm->mmap_sem);
 450         retval = error;
 451         if (error != start_addr)
 452                 goto out;
 453
 454         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 455         bss = ex.a_text + ex.a_data + ex.a_bss;
 456         if (bss > len) {
 457                 down_write(&current->mm->mmap_sem);
 458                 error = do_brk(start_addr + len, bss - len);
 459                 up_write(&current->mm->mmap_sem);
 460                 retval = error;
 461                 if (error != start_addr + len)
 462                         goto out;
 463         }
 464         retval = 0;
 465 out:
 466         return retval;
 467 }
 468
 469 static int __init init_aout_binfmt(void)
 470 {
 471         return register_binfmt(&aout_format);
 472 }
 473
 474 static void __exit exit_aout_binfmt(void)
 475 {
 476         unregister_binfmt(&aout_format);
 477 }
 478
 479 core_initcall(init_aout_binfmt);
 480 module_exit(exit_aout_binfmt);
 481 MODULE_LICENSE("GPL");