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