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