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 *);
  34 static int load_aout_library(struct file*);
  35
  36 #ifdef CONFIG_COREDUMP
  37 /*
  38  * Routine writes a core dump image in the current directory.
  39  * Currently only a stub-function.
  40  *
  41  * Note that setuid/setgid files won't make a core-dump if the uid/gid
  42  * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
  43  * field, which also makes sure the core-dumps won't be recursive if the
  44  * dumping of the process results in another error..
  45  */
  46 static int aout_core_dump(struct coredump_params *cprm)
  47 {
  48         struct file *file = cprm->file;
  49         mm_segment_t fs;
  50         int has_dumped = 0;
  51         void __user *dump_start;
  52         int dump_size;
  53         struct user dump;
  54 #ifdef __alpha__
  55 #       define START_DATA(u)    ((void __user *)u.start_data)
  56 #else
  57 #       define START_DATA(u)    ((void __user *)((u.u_tsize << PAGE_SHIFT) + \
  58                                  u.start_code))
  59 #endif
  60 #       define START_STACK(u)   ((void __user *)u.start_stack)
  61
  62         fs = get_fs();
  63         set_fs(KERNEL_DS);
  64         has_dumped = 1;
  65         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
  66         dump.u_ar0 = offsetof(struct user, regs);
  67         dump.signal = cprm->siginfo->si_signo;
  68         aout_dump_thread(cprm->regs, &dump);
  69
  70 /* If the size of the dump file exceeds the rlimit, then see what would happen
  71    if we wrote the stack, but not the data area.  */
  72         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
  73                 dump.u_dsize = 0;
  74
  75 /* Make sure we have enough room to write the stack and data areas. */
  76         if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
  77                 dump.u_ssize = 0;
  78
  79 /* make sure we actually have a data and stack area to dump */
  80         set_fs(USER_DS);
  81         if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
  82                 dump.u_dsize = 0;
  83         if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
  84                 dump.u_ssize = 0;
  85
  86         set_fs(KERNEL_DS);
  87 /* struct user */
  88         if (!dump_write(file, &dump, sizeof(dump)))
  89                 goto end_coredump;
  90 /* Now dump all of the user data.  Include malloced stuff as well */
  91         if (!dump_seek(cprm->file, PAGE_SIZE - sizeof(dump)))
  92                 goto end_coredump;
  93 /* now we start writing out the user space info */
  94         set_fs(USER_DS);
  95 /* Dump the data area */
  96         if (dump.u_dsize != 0) {
  97                 dump_start = START_DATA(dump);
  98                 dump_size = dump.u_dsize << PAGE_SHIFT;
  99                 if (!dump_write(file, dump_start, dump_size))
 100                         goto end_coredump;
 101         }
 102 /* Now prepare to dump the stack area */
 103         if (dump.u_ssize != 0) {
 104                 dump_start = START_STACK(dump);
 105                 dump_size = dump.u_ssize << PAGE_SHIFT;
 106                 if (!dump_write(file, dump_start, dump_size))
 107                         goto end_coredump;
 108         }
 109 end_coredump:
 110         set_fs(fs);
 111         return has_dumped;
 112 }
 113 #else
 114 #define aout_core_dump NULL
 115 #endif
 116
 117 static struct linux_binfmt aout_format = {
 118         .module         = THIS_MODULE,
 119         .load_binary    = load_aout_binary,
 120         .load_shlib     = load_aout_library,
 121         .core_dump      = aout_core_dump,
 122         .min_coredump   = PAGE_SIZE
 123 };
 124
 125 #define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
 126
 127 static int set_brk(unsigned long start, unsigned long end)
 128 {
 129         start = PAGE_ALIGN(start);
 130         end = PAGE_ALIGN(end);
 131         if (end > start) {
 132                 unsigned long addr;
 133                 addr = vm_brk(start, end - start);
 134                 if (BAD_ADDR(addr))
 135                         return addr;
 136         }
 137         return 0;
 138 }
 139
 140 /*
 141  * create_aout_tables() parses the env- and arg-strings in new user
 142  * memory and creates the pointer tables from them, and puts their
 143  * addresses on the "stack", returning the new stack pointer value.
 144  */
 145 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
 146 {
 147         char __user * __user *argv;
 148         char __user * __user *envp;
 149         unsigned long __user *sp;
 150         int argc = bprm->argc;
 151         int envc = bprm->envc;
 152
 153         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
 154 #ifdef __alpha__
 155 /* whee.. test-programs are so much fun. */
 156         put_user(0, --sp);
 157         put_user(0, --sp);
 158         if (bprm->loader) {
 159                 put_user(0, --sp);
 160                 put_user(1003, --sp);
 161                 put_user(bprm->loader, --sp);
 162                 put_user(1002, --sp);
 163         }
 164         put_user(bprm->exec, --sp);
 165         put_user(1001, --sp);
 166 #endif
 167         sp -= envc+1;
 168         envp = (char __user * __user *) sp;
 169         sp -= argc+1;
 170         argv = (char __user * __user *) sp;
 171 #ifndef __alpha__
 172         put_user((unsigned long) envp,--sp);
 173         put_user((unsigned long) argv,--sp);
 174 #endif
 175         put_user(argc,--sp);
 176         current->mm->arg_start = (unsigned long) p;
 177         while (argc-->0) {
 178                 char c;
 179                 put_user(p,argv++);
 180                 do {
 181                         get_user(c,p++);
 182                 } while (c);
 183         }
 184         put_user(NULL,argv);
 185         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 186         while (envc-->0) {
 187                 char c;
 188                 put_user(p,envp++);
 189                 do {
 190                         get_user(c,p++);
 191                 } while (c);
 192         }
 193         put_user(NULL,envp);
 194         current->mm->env_end = (unsigned long) p;
 195         return sp;
 196 }
 197
 198 /*
 199  * These are the functions used to load a.out style executables and shared
 200  * libraries.  There is no binary dependent code anywhere else.
 201  */
 202
 203 static int load_aout_binary(struct linux_binprm * bprm)
 204 {
 205         struct pt_regs *regs = current_pt_regs();
 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(file_inode(bprm->file)) < 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
 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 = read_code(bprm->file, text_addr, pos,
 288                                   ex.a_text+ex.a_data);
 289                 if ((signed long)error < 0) {
 290                         send_sig(SIGKILL, current, 0);
 291                         return error;
 292                 }
 293         } else {
 294                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 295                     (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
 296                 {
 297                         printk(KERN_NOTICE "executable not page aligned\n");
 298                 }
 299
 300                 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
 301                 {
 302                         printk(KERN_WARNING
 303                                "fd_offset is not page aligned. Please convert program: %s\n",
 304                                bprm->file->f_path.dentry->d_name.name);
 305                 }
 306
 307                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 308                         vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 309                         read_code(bprm->file, N_TXTADDR(ex), fd_offset,
 310                                   ex.a_text + ex.a_data);
 311                         goto beyond_if;
 312                 }
 313
 314                 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 315                         PROT_READ | PROT_EXEC,
 316                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 317                         fd_offset);
 318
 319                 if (error != N_TXTADDR(ex)) {
 320                         send_sig(SIGKILL, current, 0);
 321                         return error;
 322                 }
 323
 324                 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 325                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 326                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 327                                 fd_offset + ex.a_text);
 328                 if (error != N_DATADDR(ex)) {
 329                         send_sig(SIGKILL, current, 0);
 330                         return error;
 331                 }
 332         }
 333 beyond_if:
 334         set_binfmt(&aout_format);
 335
 336         retval = set_brk(current->mm->start_brk, current->mm->brk);
 337         if (retval < 0) {
 338                 send_sig(SIGKILL, current, 0);
 339                 return retval;
 340         }
 341
 342         current->mm->start_stack =
 343                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 344 #ifdef __alpha__
 345         regs->gp = ex.a_gpvalue;
 346 #endif
 347         start_thread(regs, ex.a_entry, current->mm->start_stack);
 348         return 0;
 349 }
 350
 351 static int load_aout_library(struct file *file)
 352 {
 353         struct inode * inode;
 354         unsigned long bss, start_addr, len;
 355         unsigned long error;
 356         int retval;
 357         struct exec ex;
 358
 359         inode = file_inode(file);
 360
 361         retval = -ENOEXEC;
 362         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 363         if (error != sizeof(ex))
 364                 goto out;
 365
 366         /* We come in here for the regular a.out style of shared libraries */
 367         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 368             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 369             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 370                 goto out;
 371         }
 372
 373         /*
 374          * Requires a mmap handler. This prevents people from using a.out
 375          * as part of an exploit attack against /proc-related vulnerabilities.
 376          */
 377         if (!file->f_op || !file->f_op->mmap)
 378                 goto out;
 379
 380         if (N_FLAGS(ex))
 381                 goto out;
 382
 383         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 384            this off to get the starting address for the page */
 385
 386         start_addr =  ex.a_entry & 0xfffff000;
 387
 388         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 389                 if (printk_ratelimit())
 390                 {
 391                         printk(KERN_WARNING
 392                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
 393                                file->f_path.dentry->d_name.name);
 394                 }
 395                 vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 396
 397                 read_code(file, start_addr, N_TXTOFF(ex),
 398                           ex.a_text + ex.a_data);
 399                 retval = 0;
 400                 goto out;
 401         }
 402         /* Now use mmap to map the library into memory. */
 403         error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
 404                         PROT_READ | PROT_WRITE | PROT_EXEC,
 405                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 406                         N_TXTOFF(ex));
 407         retval = error;
 408         if (error != start_addr)
 409                 goto out;
 410
 411         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 412         bss = ex.a_text + ex.a_data + ex.a_bss;
 413         if (bss > len) {
 414                 error = vm_brk(start_addr + len, bss - len);
 415                 retval = error;
 416                 if (error != start_addr + len)
 417                         goto out;
 418         }
 419         retval = 0;
 420 out:
 421         return retval;
 422 }
 423
 424 static int __init init_aout_binfmt(void)
 425 {
 426         register_binfmt(&aout_format);
 427         return 0;
 428 }
 429
 430 static void __exit exit_aout_binfmt(void)
 431 {
 432         unregister_binfmt(&aout_format);
 433 }
 434
 435 core_initcall(init_aout_binfmt);
 436 module_exit(exit_aout_binfmt);
 437 MODULE_LICENSE("GPL");