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