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         current->flags |= PF_DUMPCORE;
  66         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
  67         dump.u_ar0 = offsetof(struct user, regs);
  68         dump.signal = cprm->siginfo->si_signo;
  69         aout_dump_thread(cprm->regs, &dump);
  70
  71 /* If the size of the dump file exceeds the rlimit, then see what would happen
  72    if we wrote the stack, but not the data area.  */
  73         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
  74                 dump.u_dsize = 0;
  75
  76 /* Make sure we have enough room to write the stack and data areas. */
  77         if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
  78                 dump.u_ssize = 0;
  79
  80 /* make sure we actually have a data and stack area to dump */
  81         set_fs(USER_DS);
  82         if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
  83                 dump.u_dsize = 0;
  84         if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
  85                 dump.u_ssize = 0;
  86
  87         set_fs(KERNEL_DS);
  88 /* struct user */
  89         if (!dump_write(file, &dump, sizeof(dump)))
  90                 goto end_coredump;
  91 /* Now dump all of the user data.  Include malloced stuff as well */
  92         if (!dump_seek(cprm->file, PAGE_SIZE - sizeof(dump)))
  93                 goto end_coredump;
  94 /* now we start writing out the user space info */
  95         set_fs(USER_DS);
  96 /* Dump the data area */
  97         if (dump.u_dsize != 0) {
  98                 dump_start = START_DATA(dump);
  99                 dump_size = dump.u_dsize << PAGE_SHIFT;
 100                 if (!dump_write(file, dump_start, dump_size))
 101                         goto end_coredump;
 102         }
 103 /* Now prepare to dump the stack area */
 104         if (dump.u_ssize != 0) {
 105                 dump_start = START_STACK(dump);
 106                 dump_size = dump.u_ssize << PAGE_SHIFT;
 107                 if (!dump_write(file, dump_start, dump_size))
 108                         goto end_coredump;
 109         }
 110 end_coredump:
 111         set_fs(fs);
 112         return has_dumped;
 113 }
 114 #else
 115 #define aout_core_dump NULL
 116 #endif
 117
 118 static struct linux_binfmt aout_format = {
 119         .module         = THIS_MODULE,
 120         .load_binary    = load_aout_binary,
 121         .load_shlib     = load_aout_library,
 122         .core_dump      = aout_core_dump,
 123         .min_coredump   = PAGE_SIZE
 124 };
 125
 126 #define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
 127
 128 static int set_brk(unsigned long start, unsigned long end)
 129 {
 130         start = PAGE_ALIGN(start);
 131         end = PAGE_ALIGN(end);
 132         if (end > start) {
 133                 unsigned long addr;
 134                 addr = vm_brk(start, end - start);
 135                 if (BAD_ADDR(addr))
 136                         return addr;
 137         }
 138         return 0;
 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)
 205 {
 206         struct pt_regs *regs = current_pt_regs();
 207         struct exec ex;
 208         unsigned long error;
 209         unsigned long fd_offset;
 210         unsigned long rlim;
 211         int retval;
 212
 213         ex = *((struct exec *) bprm->buf);              /* exec-header */
 214         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 215              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 216             N_TRSIZE(ex) || N_DRSIZE(ex) ||
 217             i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 218                 return -ENOEXEC;
 219         }
 220
 221         /*
 222          * Requires a mmap handler. This prevents people from using a.out
 223          * as part of an exploit attack against /proc-related vulnerabilities.
 224          */
 225         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
 226                 return -ENOEXEC;
 227
 228         fd_offset = N_TXTOFF(ex);
 229
 230         /* Check initial limits. This avoids letting people circumvent
 231          * size limits imposed on them by creating programs with large
 232          * arrays in the data or bss.
 233          */
 234         rlim = rlimit(RLIMIT_DATA);
 235         if (rlim >= RLIM_INFINITY)
 236                 rlim = ~0;
 237         if (ex.a_data + ex.a_bss > rlim)
 238                 return -ENOMEM;
 239
 240         /* Flush all traces of the currently running executable */
 241         retval = flush_old_exec(bprm);
 242         if (retval)
 243                 return retval;
 244
 245         /* OK, This is the point of no return */
 246 #ifdef __alpha__
 247         SET_AOUT_PERSONALITY(bprm, ex);
 248 #else
 249         set_personality(PER_LINUX);
 250 #endif
 251         setup_new_exec(bprm);
 252
 253         current->mm->end_code = ex.a_text +
 254                 (current->mm->start_code = N_TXTADDR(ex));
 255         current->mm->end_data = ex.a_data +
 256                 (current->mm->start_data = N_DATADDR(ex));
 257         current->mm->brk = ex.a_bss +
 258                 (current->mm->start_brk = N_BSSADDR(ex));
 259         current->mm->free_area_cache = current->mm->mmap_base;
 260         current->mm->cached_hole_size = 0;
 261
 262         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 263         if (retval < 0) {
 264                 /* Someone check-me: is this error path enough? */
 265                 send_sig(SIGKILL, current, 0);
 266                 return retval;
 267         }
 268
 269         install_exec_creds(bprm);
 270
 271         if (N_MAGIC(ex) == OMAGIC) {
 272                 unsigned long text_addr, map_size;
 273                 loff_t pos;
 274
 275                 text_addr = N_TXTADDR(ex);
 276
 277 #ifdef __alpha__
 278                 pos = fd_offset;
 279                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 280 #else
 281                 pos = 32;
 282                 map_size = ex.a_text+ex.a_data;
 283 #endif
 284                 error = vm_brk(text_addr & PAGE_MASK, map_size);
 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                         vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 316                         bprm->file->f_op->read(bprm->file,
 317                                         (char __user *)N_TXTADDR(ex),
 318                                         ex.a_text+ex.a_data, &pos);
 319                         flush_icache_range((unsigned long) N_TXTADDR(ex),
 320                                            (unsigned long) N_TXTADDR(ex) +
 321                                            ex.a_text+ex.a_data);
 322                         goto beyond_if;
 323                 }
 324
 325                 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 326                         PROT_READ | PROT_EXEC,
 327                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 328                         fd_offset);
 329
 330                 if (error != N_TXTADDR(ex)) {
 331                         send_sig(SIGKILL, current, 0);
 332                         return error;
 333                 }
 334
 335                 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 336                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 337                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 338                                 fd_offset + ex.a_text);
 339                 if (error != N_DATADDR(ex)) {
 340                         send_sig(SIGKILL, current, 0);
 341                         return error;
 342                 }
 343         }
 344 beyond_if:
 345         set_binfmt(&aout_format);
 346
 347         retval = set_brk(current->mm->start_brk, current->mm->brk);
 348         if (retval < 0) {
 349                 send_sig(SIGKILL, current, 0);
 350                 return retval;
 351         }
 352
 353         current->mm->start_stack =
 354                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 355 #ifdef __alpha__
 356         regs->gp = ex.a_gpvalue;
 357 #endif
 358         start_thread(regs, ex.a_entry, current->mm->start_stack);
 359         return 0;
 360 }
 361
 362 static int load_aout_library(struct file *file)
 363 {
 364         struct inode * inode;
 365         unsigned long bss, start_addr, len;
 366         unsigned long error;
 367         int retval;
 368         struct exec ex;
 369
 370         inode = file_inode(file);
 371
 372         retval = -ENOEXEC;
 373         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 374         if (error != sizeof(ex))
 375                 goto out;
 376
 377         /* We come in here for the regular a.out style of shared libraries */
 378         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 379             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 380             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 381                 goto out;
 382         }
 383
 384         /*
 385          * Requires a mmap handler. This prevents people from using a.out
 386          * as part of an exploit attack against /proc-related vulnerabilities.
 387          */
 388         if (!file->f_op || !file->f_op->mmap)
 389                 goto out;
 390
 391         if (N_FLAGS(ex))
 392                 goto out;
 393
 394         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 395            this off to get the starting address for the page */
 396
 397         start_addr =  ex.a_entry & 0xfffff000;
 398
 399         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 400                 loff_t pos = N_TXTOFF(ex);
 401
 402                 if (printk_ratelimit())
 403                 {
 404                         printk(KERN_WARNING
 405                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
 406                                file->f_path.dentry->d_name.name);
 407                 }
 408                 vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 409
 410                 file->f_op->read(file, (char __user *)start_addr,
 411                         ex.a_text + ex.a_data, &pos);
 412                 flush_icache_range((unsigned long) start_addr,
 413                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
 414
 415                 retval = 0;
 416                 goto out;
 417         }
 418         /* Now use mmap to map the library into memory. */
 419         error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
 420                         PROT_READ | PROT_WRITE | PROT_EXEC,
 421                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 422                         N_TXTOFF(ex));
 423         retval = error;
 424         if (error != start_addr)
 425                 goto out;
 426
 427         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 428         bss = ex.a_text + ex.a_data + ex.a_bss;
 429         if (bss > len) {
 430                 error = vm_brk(start_addr + len, bss - len);
 431                 retval = error;
 432                 if (error != start_addr + len)
 433                         goto out;
 434         }
 435         retval = 0;
 436 out:
 437         return retval;
 438 }
 439
 440 static int __init init_aout_binfmt(void)
 441 {
 442         register_binfmt(&aout_format);
 443         return 0;
 444 }
 445
 446 static void __exit exit_aout_binfmt(void)
 447 {
 448         unregister_binfmt(&aout_format);
 449 }
 450
 451 core_initcall(init_aout_binfmt);
 452 module_exit(exit_aout_binfmt);
 453 MODULE_LICENSE("GPL");