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(struct coredump_params *cprm);
  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 static int dump_seek(struct file *file, loff_t off)
  73 {
  74         if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
  75                 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
  76                         return 0;
  77         } else {
  78                 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
  79                 if (!buf)
  80                         return 0;
  81                 while (off > 0) {
  82                         unsigned long n = off;
  83                         if (n > PAGE_SIZE)
  84                                 n = PAGE_SIZE;
  85                         if (!dump_write(file, buf, n))
  86                                 return 0;
  87                         off -= n;
  88                 }
  89                 free_page((unsigned long)buf);
  90         }
  91         return 1;
  92 }
  93
  94 #define DUMP_WRITE(addr, nr)    \
  95         if (!dump_write(file, (void *)(addr), (nr))) \
  96                 goto end_coredump;
  97
  98 /*
  99  * Routine writes a core dump image in the current directory.
 100  * Currently only a stub-function.
 101  *
 102  * Note that setuid/setgid files won't make a core-dump if the uid/gid
 103  * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
 104  * field, which also makes sure the core-dumps won't be recursive if the
 105  * dumping of the process results in another error..
 106  */
 107
 108 static int aout_core_dump(struct coredump_params *cprm)
 109 {
 110         struct file *file = cprm->file;
 111         mm_segment_t fs;
 112         int has_dumped = 0;
 113         unsigned long dump_start, dump_size;
 114         struct user dump;
 115 #ifdef __alpha__
 116 #       define START_DATA(u)    (u.start_data)
 117 #else
 118 #       define START_DATA(u)    ((u.u_tsize << PAGE_SHIFT) + u.start_code)
 119 #endif
 120 #       define START_STACK(u)   (u.start_stack)
 121
 122         fs = get_fs();
 123         set_fs(KERNEL_DS);
 124         has_dumped = 1;
 125         current->flags |= PF_DUMPCORE;
 126         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
 127         dump.u_ar0 = offsetof(struct user, regs);
 128         dump.signal = cprm->signr;
 129         aout_dump_thread(cprm->regs, &dump);
 130
 131 /* If the size of the dump file exceeds the rlimit, then see what would happen
 132    if we wrote the stack, but not the data area.  */
 133         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
 134                 dump.u_dsize = 0;
 135
 136 /* Make sure we have enough room to write the stack and data areas. */
 137         if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
 138                 dump.u_ssize = 0;
 139
 140 /* make sure we actually have a data and stack area to dump */
 141         set_fs(USER_DS);
 142         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
 143                 dump.u_dsize = 0;
 144         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
 145                 dump.u_ssize = 0;
 146
 147         set_fs(KERNEL_DS);
 148 /* struct user */
 149         DUMP_WRITE(&dump,sizeof(dump));
 150 /* Now dump all of the user data.  Include malloced stuff as well */
 151         if (!dump_seek(cprm->file, PAGE_SIZE - sizeof(dump)))
 152                 goto end_coredump;
 153 /* now we start writing out the user space info */
 154         set_fs(USER_DS);
 155 /* Dump the data area */
 156         if (dump.u_dsize != 0) {
 157                 dump_start = START_DATA(dump);
 158                 dump_size = dump.u_dsize << PAGE_SHIFT;
 159                 DUMP_WRITE(dump_start,dump_size);
 160         }
 161 /* Now prepare to dump the stack area */
 162         if (dump.u_ssize != 0) {
 163                 dump_start = START_STACK(dump);
 164                 dump_size = dump.u_ssize << PAGE_SHIFT;
 165                 DUMP_WRITE(dump_start,dump_size);
 166         }
 167 /* Finally dump the task struct.  Not be used by gdb, but could be useful */
 168         set_fs(KERNEL_DS);
 169         DUMP_WRITE(current,sizeof(*current));
 170 end_coredump:
 171         set_fs(fs);
 172         return has_dumped;
 173 }
 174
 175 /*
 176  * create_aout_tables() parses the env- and arg-strings in new user
 177  * memory and creates the pointer tables from them, and puts their
 178  * addresses on the "stack", returning the new stack pointer value.
 179  */
 180 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
 181 {
 182         char __user * __user *argv;
 183         char __user * __user *envp;
 184         unsigned long __user *sp;
 185         int argc = bprm->argc;
 186         int envc = bprm->envc;
 187
 188         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
 189 #ifdef __alpha__
 190 /* whee.. test-programs are so much fun. */
 191         put_user(0, --sp);
 192         put_user(0, --sp);
 193         if (bprm->loader) {
 194                 put_user(0, --sp);
 195                 put_user(1003, --sp);
 196                 put_user(bprm->loader, --sp);
 197                 put_user(1002, --sp);
 198         }
 199         put_user(bprm->exec, --sp);
 200         put_user(1001, --sp);
 201 #endif
 202         sp -= envc+1;
 203         envp = (char __user * __user *) sp;
 204         sp -= argc+1;
 205         argv = (char __user * __user *) sp;
 206 #ifndef __alpha__
 207         put_user((unsigned long) envp,--sp);
 208         put_user((unsigned long) argv,--sp);
 209 #endif
 210         put_user(argc,--sp);
 211         current->mm->arg_start = (unsigned long) p;
 212         while (argc-->0) {
 213                 char c;
 214                 put_user(p,argv++);
 215                 do {
 216                         get_user(c,p++);
 217                 } while (c);
 218         }
 219         put_user(NULL,argv);
 220         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 221         while (envc-->0) {
 222                 char c;
 223                 put_user(p,envp++);
 224                 do {
 225                         get_user(c,p++);
 226                 } while (c);
 227         }
 228         put_user(NULL,envp);
 229         current->mm->env_end = (unsigned long) p;
 230         return sp;
 231 }
 232
 233 /*
 234  * These are the functions used to load a.out style executables and shared
 235  * libraries.  There is no binary dependent code anywhere else.
 236  */
 237
 238 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 239 {
 240         struct exec ex;
 241         unsigned long error;
 242         unsigned long fd_offset;
 243         unsigned long rlim;
 244         int retval;
 245
 246         ex = *((struct exec *) bprm->buf);              /* exec-header */
 247         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 248              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 249             N_TRSIZE(ex) || N_DRSIZE(ex) ||
 250             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 251                 return -ENOEXEC;
 252         }
 253
 254         /*
 255          * Requires a mmap handler. This prevents people from using a.out
 256          * as part of an exploit attack against /proc-related vulnerabilities.
 257          */
 258         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
 259                 return -ENOEXEC;
 260
 261         fd_offset = N_TXTOFF(ex);
 262
 263         /* Check initial limits. This avoids letting people circumvent
 264          * size limits imposed on them by creating programs with large
 265          * arrays in the data or bss.
 266          */
 267         rlim = rlimit(RLIMIT_DATA);
 268         if (rlim >= RLIM_INFINITY)
 269                 rlim = ~0;
 270         if (ex.a_data + ex.a_bss > rlim)
 271                 return -ENOMEM;
 272
 273         /* Flush all traces of the currently running executable */
 274         retval = flush_old_exec(bprm);
 275         if (retval)
 276                 return retval;
 277
 278         /* OK, This is the point of no return */
 279 #ifdef __alpha__
 280         SET_AOUT_PERSONALITY(bprm, ex);
 281 #else
 282         set_personality(PER_LINUX);
 283 #endif
 284         setup_new_exec(bprm);
 285
 286         current->mm->end_code = ex.a_text +
 287                 (current->mm->start_code = N_TXTADDR(ex));
 288         current->mm->end_data = ex.a_data +
 289                 (current->mm->start_data = N_DATADDR(ex));
 290         current->mm->brk = ex.a_bss +
 291                 (current->mm->start_brk = N_BSSADDR(ex));
 292         current->mm->free_area_cache = current->mm->mmap_base;
 293         current->mm->cached_hole_size = 0;
 294
 295         install_exec_creds(bprm);
 296         current->flags &= ~PF_FORKNOEXEC;
 297
 298         if (N_MAGIC(ex) == OMAGIC) {
 299                 unsigned long text_addr, map_size;
 300                 loff_t pos;
 301
 302                 text_addr = N_TXTADDR(ex);
 303
 304 #ifdef __alpha__
 305                 pos = fd_offset;
 306                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 307 #else
 308                 pos = 32;
 309                 map_size = ex.a_text+ex.a_data;
 310 #endif
 311                 down_write(&current->mm->mmap_sem);
 312                 error = do_brk(text_addr & PAGE_MASK, map_size);
 313                 up_write(&current->mm->mmap_sem);
 314                 if (error != (text_addr & PAGE_MASK)) {
 315                         send_sig(SIGKILL, current, 0);
 316                         return error;
 317                 }
 318
 319                 error = bprm->file->f_op->read(bprm->file,
 320                           (char __user *)text_addr,
 321                           ex.a_text+ex.a_data, &pos);
 322                 if ((signed long)error < 0) {
 323                         send_sig(SIGKILL, current, 0);
 324                         return error;
 325                 }
 326
 327                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
 328         } else {
 329                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 330                     (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
 331                 {
 332                         printk(KERN_NOTICE "executable not page aligned\n");
 333                 }
 334
 335                 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
 336                 {
 337                         printk(KERN_WARNING
 338                                "fd_offset is not page aligned. Please convert program: %s\n",
 339                                bprm->file->f_path.dentry->d_name.name);
 340                 }
 341
 342                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 343                         loff_t pos = fd_offset;
 344                         down_write(&current->mm->mmap_sem);
 345                         do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 346                         up_write(&current->mm->mmap_sem);
 347                         bprm->file->f_op->read(bprm->file,
 348                                         (char __user *)N_TXTADDR(ex),
 349                                         ex.a_text+ex.a_data, &pos);
 350                         flush_icache_range((unsigned long) N_TXTADDR(ex),
 351                                            (unsigned long) N_TXTADDR(ex) +
 352                                            ex.a_text+ex.a_data);
 353                         goto beyond_if;
 354                 }
 355
 356                 down_write(&current->mm->mmap_sem);
 357                 error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 358                         PROT_READ | PROT_EXEC,
 359                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 360                         fd_offset);
 361                 up_write(&current->mm->mmap_sem);
 362
 363                 if (error != N_TXTADDR(ex)) {
 364                         send_sig(SIGKILL, current, 0);
 365                         return error;
 366                 }
 367
 368                 down_write(&current->mm->mmap_sem);
 369                 error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 370                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 371                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 372                                 fd_offset + ex.a_text);
 373                 up_write(&current->mm->mmap_sem);
 374                 if (error != N_DATADDR(ex)) {
 375                         send_sig(SIGKILL, current, 0);
 376                         return error;
 377                 }
 378         }
 379 beyond_if:
 380         set_binfmt(&aout_format);
 381
 382         retval = set_brk(current->mm->start_brk, current->mm->brk);
 383         if (retval < 0) {
 384                 send_sig(SIGKILL, current, 0);
 385                 return retval;
 386         }
 387
 388         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 389         if (retval < 0) {
 390                 /* Someone check-me: is this error path enough? */
 391                 send_sig(SIGKILL, current, 0);
 392                 return retval;
 393         }
 394
 395         current->mm->start_stack =
 396                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 397 #ifdef __alpha__
 398         regs->gp = ex.a_gpvalue;
 399 #endif
 400         start_thread(regs, ex.a_entry, current->mm->start_stack);
 401         return 0;
 402 }
 403
 404 static int load_aout_library(struct file *file)
 405 {
 406         struct inode * inode;
 407         unsigned long bss, start_addr, len;
 408         unsigned long error;
 409         int retval;
 410         struct exec ex;
 411
 412         inode = file->f_path.dentry->d_inode;
 413
 414         retval = -ENOEXEC;
 415         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 416         if (error != sizeof(ex))
 417                 goto out;
 418
 419         /* We come in here for the regular a.out style of shared libraries */
 420         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 421             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 422             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 423                 goto out;
 424         }
 425
 426         /*
 427          * Requires a mmap handler. This prevents people from using a.out
 428          * as part of an exploit attack against /proc-related vulnerabilities.
 429          */
 430         if (!file->f_op || !file->f_op->mmap)
 431                 goto out;
 432
 433         if (N_FLAGS(ex))
 434                 goto out;
 435
 436         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 437            this off to get the starting address for the page */
 438
 439         start_addr =  ex.a_entry & 0xfffff000;
 440
 441         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 442                 loff_t pos = N_TXTOFF(ex);
 443
 444                 if (printk_ratelimit())
 445                 {
 446                         printk(KERN_WARNING
 447                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
 448                                file->f_path.dentry->d_name.name);
 449                 }
 450                 down_write(&current->mm->mmap_sem);
 451                 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 452                 up_write(&current->mm->mmap_sem);
 453
 454                 file->f_op->read(file, (char __user *)start_addr,
 455                         ex.a_text + ex.a_data, &pos);
 456                 flush_icache_range((unsigned long) start_addr,
 457                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
 458
 459                 retval = 0;
 460                 goto out;
 461         }
 462         /* Now use mmap to map the library into memory. */
 463         down_write(&current->mm->mmap_sem);
 464         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
 465                         PROT_READ | PROT_WRITE | PROT_EXEC,
 466                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 467                         N_TXTOFF(ex));
 468         up_write(&current->mm->mmap_sem);
 469         retval = error;
 470         if (error != start_addr)
 471                 goto out;
 472
 473         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 474         bss = ex.a_text + ex.a_data + ex.a_bss;
 475         if (bss > len) {
 476                 down_write(&current->mm->mmap_sem);
 477                 error = do_brk(start_addr + len, bss - len);
 478                 up_write(&current->mm->mmap_sem);
 479                 retval = error;
 480                 if (error != start_addr + len)
 481                         goto out;
 482         }
 483         retval = 0;
 484 out:
 485         return retval;
 486 }
 487
 488 static int __init init_aout_binfmt(void)
 489 {
 490         return register_binfmt(&aout_format);
 491 }
 492
 493 static void __exit exit_aout_binfmt(void)
 494 {
 495         unregister_binfmt(&aout_format);
 496 }
 497
 498 core_initcall(init_aout_binfmt);
 499 module_exit(exit_aout_binfmt);
 500 MODULE_LICENSE("GPL");