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