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/binfmts.h>
  24 #include <linux/personality.h>
  25 #include <linux/init.h>
  26 #include <linux/coredump.h>
  27 #include <linux/slab.h>
  28
  29 #include <asm/system.h>
  30 #include <asm/uaccess.h>
  31 #include <asm/cacheflush.h>
  32 #include <asm/a.out-core.h>
  33
  34 static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
  35 static int load_aout_library(struct file*);
  36 static int aout_core_dump(struct coredump_params *cprm);
  37
  38 static struct linux_binfmt aout_format = {
  39         .module         = THIS_MODULE,
  40         .load_binary    = load_aout_binary,
  41         .load_shlib     = load_aout_library,
  42         .core_dump      = aout_core_dump,
  43         .min_coredump   = PAGE_SIZE
  44 };
  45
  46 #define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
  47
  48 static int set_brk(unsigned long start, unsigned long end)
  49 {
  50         start = PAGE_ALIGN(start);
  51         end = PAGE_ALIGN(end);
  52         if (end > start) {
  53                 unsigned long addr;
  54                 down_write(&current->mm->mmap_sem);
  55                 addr = do_brk(start, end - start);
  56                 up_write(&current->mm->mmap_sem);
  57                 if (BAD_ADDR(addr))
  58                         return addr;
  59         }
  60         return 0;
  61 }
  62
  63 /*
  64  * Routine writes a core dump image in the current directory.
  65  * Currently only a stub-function.
  66  *
  67  * Note that setuid/setgid files won't make a core-dump if the uid/gid
  68  * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
  69  * field, which also makes sure the core-dumps won't be recursive if the
  70  * dumping of the process results in another error..
  71  */
  72
  73 static int aout_core_dump(struct coredump_params *cprm)
  74 {
  75         struct file *file = cprm->file;
  76         mm_segment_t fs;
  77         int has_dumped = 0;
  78         void __user *dump_start;
  79         int dump_size;
  80         struct user dump;
  81 #ifdef __alpha__
  82 #       define START_DATA(u)    ((void __user *)u.start_data)
  83 #else
  84 #       define START_DATA(u)    ((void __user *)((u.u_tsize << PAGE_SHIFT) + \
  85                                  u.start_code))
  86 #endif
  87 #       define START_STACK(u)   ((void __user *)u.start_stack)
  88
  89         fs = get_fs();
  90         set_fs(KERNEL_DS);
  91         has_dumped = 1;
  92         current->flags |= PF_DUMPCORE;
  93         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
  94         dump.u_ar0 = offsetof(struct user, regs);
  95         dump.signal = cprm->signr;
  96         aout_dump_thread(cprm->regs, &dump);
  97
  98 /* If the size of the dump file exceeds the rlimit, then see what would happen
  99    if we wrote the stack, but not the data area.  */
 100         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
 101                 dump.u_dsize = 0;
 102
 103 /* Make sure we have enough room to write the stack and data areas. */
 104         if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
 105                 dump.u_ssize = 0;
 106
 107 /* make sure we actually have a data and stack area to dump */
 108         set_fs(USER_DS);
 109         if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
 110                 dump.u_dsize = 0;
 111         if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
 112                 dump.u_ssize = 0;
 113
 114         set_fs(KERNEL_DS);
 115 /* struct user */
 116         if (!dump_write(file, &dump, sizeof(dump)))
 117                 goto end_coredump;
 118 /* Now dump all of the user data.  Include malloced stuff as well */
 119         if (!dump_seek(cprm->file, PAGE_SIZE - sizeof(dump)))
 120                 goto end_coredump;
 121 /* now we start writing out the user space info */
 122         set_fs(USER_DS);
 123 /* Dump the data area */
 124         if (dump.u_dsize != 0) {
 125                 dump_start = START_DATA(dump);
 126                 dump_size = dump.u_dsize << PAGE_SHIFT;
 127                 if (!dump_write(file, dump_start, dump_size))
 128                         goto end_coredump;
 129         }
 130 /* Now prepare to dump the stack area */
 131         if (dump.u_ssize != 0) {
 132                 dump_start = START_STACK(dump);
 133                 dump_size = dump.u_ssize << PAGE_SHIFT;
 134                 if (!dump_write(file, dump_start, dump_size))
 135                         goto end_coredump;
 136         }
 137 end_coredump:
 138         set_fs(fs);
 139         return has_dumped;
 140 }
 141
 142 /*
 143  * create_aout_tables() parses the env- and arg-strings in new user
 144  * memory and creates the pointer tables from them, and puts their
 145  * addresses on the "stack", returning the new stack pointer value.
 146  */
 147 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
 148 {
 149         char __user * __user *argv;
 150         char __user * __user *envp;
 151         unsigned long __user *sp;
 152         int argc = bprm->argc;
 153         int envc = bprm->envc;
 154
 155         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
 156 #ifdef __alpha__
 157 /* whee.. test-programs are so much fun. */
 158         put_user(0, --sp);
 159         put_user(0, --sp);
 160         if (bprm->loader) {
 161                 put_user(0, --sp);
 162                 put_user(1003, --sp);
 163                 put_user(bprm->loader, --sp);
 164                 put_user(1002, --sp);
 165         }
 166         put_user(bprm->exec, --sp);
 167         put_user(1001, --sp);
 168 #endif
 169         sp -= envc+1;
 170         envp = (char __user * __user *) sp;
 171         sp -= argc+1;
 172         argv = (char __user * __user *) sp;
 173 #ifndef __alpha__
 174         put_user((unsigned long) envp,--sp);
 175         put_user((unsigned long) argv,--sp);
 176 #endif
 177         put_user(argc,--sp);
 178         current->mm->arg_start = (unsigned long) p;
 179         while (argc-->0) {
 180                 char c;
 181                 put_user(p,argv++);
 182                 do {
 183                         get_user(c,p++);
 184                 } while (c);
 185         }
 186         put_user(NULL,argv);
 187         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 188         while (envc-->0) {
 189                 char c;
 190                 put_user(p,envp++);
 191                 do {
 192                         get_user(c,p++);
 193                 } while (c);
 194         }
 195         put_user(NULL,envp);
 196         current->mm->env_end = (unsigned long) p;
 197         return sp;
 198 }
 199
 200 /*
 201  * These are the functions used to load a.out style executables and shared
 202  * libraries.  There is no binary dependent code anywhere else.
 203  */
 204
 205 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 206 {
 207         struct exec ex;
 208         unsigned long error;
 209         unsigned long fd_offset;
 210         unsigned long rlim;
 211         int retval;
 212
 213         ex = *((struct exec *) bprm->buf);              /* exec-header */
 214         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 215              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 216             N_TRSIZE(ex) || N_DRSIZE(ex) ||
 217             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 218                 return -ENOEXEC;
 219         }
 220
 221         /*
 222          * Requires a mmap handler. This prevents people from using a.out
 223          * as part of an exploit attack against /proc-related vulnerabilities.
 224          */
 225         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
 226                 return -ENOEXEC;
 227
 228         fd_offset = N_TXTOFF(ex);
 229
 230         /* Check initial limits. This avoids letting people circumvent
 231          * size limits imposed on them by creating programs with large
 232          * arrays in the data or bss.
 233          */
 234         rlim = rlimit(RLIMIT_DATA);
 235         if (rlim >= RLIM_INFINITY)
 236                 rlim = ~0;
 237         if (ex.a_data + ex.a_bss > rlim)
 238                 return -ENOMEM;
 239
 240         /* Flush all traces of the currently running executable */
 241         retval = flush_old_exec(bprm);
 242         if (retval)
 243                 return retval;
 244
 245         /* OK, This is the point of no return */
 246 #ifdef __alpha__
 247         SET_AOUT_PERSONALITY(bprm, ex);
 248 #else
 249         set_personality(PER_LINUX);
 250 #endif
 251         setup_new_exec(bprm);
 252
 253         current->mm->end_code = ex.a_text +
 254                 (current->mm->start_code = N_TXTADDR(ex));
 255         current->mm->end_data = ex.a_data +
 256                 (current->mm->start_data = N_DATADDR(ex));
 257         current->mm->brk = ex.a_bss +
 258                 (current->mm->start_brk = N_BSSADDR(ex));
 259         current->mm->free_area_cache = current->mm->mmap_base;
 260         current->mm->cached_hole_size = 0;
 261
 262         install_exec_creds(bprm);
 263         current->flags &= ~PF_FORKNOEXEC;
 264
 265         if (N_MAGIC(ex) == OMAGIC) {
 266                 unsigned long text_addr, map_size;
 267                 loff_t pos;
 268
 269                 text_addr = N_TXTADDR(ex);
 270
 271 #ifdef __alpha__
 272                 pos = fd_offset;
 273                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 274 #else
 275                 pos = 32;
 276                 map_size = ex.a_text+ex.a_data;
 277 #endif
 278                 down_write(&current->mm->mmap_sem);
 279                 error = do_brk(text_addr & PAGE_MASK, map_size);
 280                 up_write(&current->mm->mmap_sem);
 281                 if (error != (text_addr & PAGE_MASK)) {
 282                         send_sig(SIGKILL, current, 0);
 283                         return error;
 284                 }
 285
 286                 error = bprm->file->f_op->read(bprm->file,
 287                           (char __user *)text_addr,
 288                           ex.a_text+ex.a_data, &pos);
 289                 if ((signed long)error < 0) {
 290                         send_sig(SIGKILL, current, 0);
 291                         return error;
 292                 }
 293
 294                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
 295         } else {
 296                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 297                     (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
 298                 {
 299                         printk(KERN_NOTICE "executable not page aligned\n");
 300                 }
 301
 302                 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
 303                 {
 304                         printk(KERN_WARNING
 305                                "fd_offset is not page aligned. Please convert program: %s\n",
 306                                bprm->file->f_path.dentry->d_name.name);
 307                 }
 308
 309                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 310                         loff_t pos = fd_offset;
 311                         down_write(&current->mm->mmap_sem);
 312                         do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 313                         up_write(&current->mm->mmap_sem);
 314                         bprm->file->f_op->read(bprm->file,
 315                                         (char __user *)N_TXTADDR(ex),
 316                                         ex.a_text+ex.a_data, &pos);
 317                         flush_icache_range((unsigned long) N_TXTADDR(ex),
 318                                            (unsigned long) N_TXTADDR(ex) +
 319                                            ex.a_text+ex.a_data);
 320                         goto beyond_if;
 321                 }
 322
 323                 down_write(&current->mm->mmap_sem);
 324                 error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 325                         PROT_READ | PROT_EXEC,
 326                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 327                         fd_offset);
 328                 up_write(&current->mm->mmap_sem);
 329
 330                 if (error != N_TXTADDR(ex)) {
 331                         send_sig(SIGKILL, current, 0);
 332                         return error;
 333                 }
 334
 335                 down_write(&current->mm->mmap_sem);
 336                 error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 337                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 338                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 339                                 fd_offset + ex.a_text);
 340                 up_write(&current->mm->mmap_sem);
 341                 if (error != N_DATADDR(ex)) {
 342                         send_sig(SIGKILL, current, 0);
 343                         return error;
 344                 }
 345         }
 346 beyond_if:
 347         set_binfmt(&aout_format);
 348
 349         retval = set_brk(current->mm->start_brk, current->mm->brk);
 350         if (retval < 0) {
 351                 send_sig(SIGKILL, current, 0);
 352                 return retval;
 353         }
 354
 355         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 356         if (retval < 0) {
 357                 /* Someone check-me: is this error path enough? */
 358                 send_sig(SIGKILL, current, 0);
 359                 return retval;
 360         }
 361
 362         current->mm->start_stack =
 363                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 364 #ifdef __alpha__
 365         regs->gp = ex.a_gpvalue;
 366 #endif
 367         start_thread(regs, ex.a_entry, current->mm->start_stack);
 368         return 0;
 369 }
 370
 371 static int load_aout_library(struct file *file)
 372 {
 373         struct inode * inode;
 374         unsigned long bss, start_addr, len;
 375         unsigned long error;
 376         int retval;
 377         struct exec ex;
 378
 379         inode = file->f_path.dentry->d_inode;
 380
 381         retval = -ENOEXEC;
 382         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 383         if (error != sizeof(ex))
 384                 goto out;
 385
 386         /* We come in here for the regular a.out style of shared libraries */
 387         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 388             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 389             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 390                 goto out;
 391         }
 392
 393         /*
 394          * Requires a mmap handler. This prevents people from using a.out
 395          * as part of an exploit attack against /proc-related vulnerabilities.
 396          */
 397         if (!file->f_op || !file->f_op->mmap)
 398                 goto out;
 399
 400         if (N_FLAGS(ex))
 401                 goto out;
 402
 403         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 404            this off to get the starting address for the page */
 405
 406         start_addr =  ex.a_entry & 0xfffff000;
 407
 408         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 409                 loff_t pos = N_TXTOFF(ex);
 410
 411                 if (printk_ratelimit())
 412                 {
 413                         printk(KERN_WARNING
 414                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
 415                                file->f_path.dentry->d_name.name);
 416                 }
 417                 down_write(&current->mm->mmap_sem);
 418                 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 419                 up_write(&current->mm->mmap_sem);
 420
 421                 file->f_op->read(file, (char __user *)start_addr,
 422                         ex.a_text + ex.a_data, &pos);
 423                 flush_icache_range((unsigned long) start_addr,
 424                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
 425
 426                 retval = 0;
 427                 goto out;
 428         }
 429         /* Now use mmap to map the library into memory. */
 430         down_write(&current->mm->mmap_sem);
 431         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
 432                         PROT_READ | PROT_WRITE | PROT_EXEC,
 433                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 434                         N_TXTOFF(ex));
 435         up_write(&current->mm->mmap_sem);
 436         retval = error;
 437         if (error != start_addr)
 438                 goto out;
 439
 440         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 441         bss = ex.a_text + ex.a_data + ex.a_bss;
 442         if (bss > len) {
 443                 down_write(&current->mm->mmap_sem);
 444                 error = do_brk(start_addr + len, bss - len);
 445                 up_write(&current->mm->mmap_sem);
 446                 retval = error;
 447                 if (error != start_addr + len)
 448                         goto out;
 449         }
 450         retval = 0;
 451 out:
 452         return retval;
 453 }
 454
 455 static int __init init_aout_binfmt(void)
 456 {
 457         return register_binfmt(&aout_format);
 458 }
 459
 460 static void __exit exit_aout_binfmt(void)
 461 {
 462         unregister_binfmt(&aout_format);
 463 }
 464
 465 core_initcall(init_aout_binfmt);
 466 module_exit(exit_aout_binfmt);
 467 MODULE_LICENSE("GPL");