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