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         mm_segment_t fs;
  49         int has_dumped = 0;
  50         void __user *dump_start;
  51         int dump_size;
  52         struct user dump;
  53 #ifdef __alpha__
  54 #       define START_DATA(u)    ((void __user *)u.start_data)
  55 #else
  56 #       define START_DATA(u)    ((void __user *)((u.u_tsize << PAGE_SHIFT) + \
  57                                  u.start_code))
  58 #endif
  59 #       define START_STACK(u)   ((void __user *)u.start_stack)
  60
  61         fs = get_fs();
  62         set_fs(KERNEL_DS);
  63         has_dumped = 1;
  64         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
  65         dump.u_ar0 = offsetof(struct user, regs);
  66         dump.signal = cprm->siginfo->si_signo;
  67         aout_dump_thread(cprm->regs, &dump);
  68
  69 /* If the size of the dump file exceeds the rlimit, then see what would happen
  70    if we wrote the stack, but not the data area.  */
  71         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
  72                 dump.u_dsize = 0;
  73
  74 /* Make sure we have enough room to write the stack and data areas. */
  75         if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
  76                 dump.u_ssize = 0;
  77
  78 /* make sure we actually have a data and stack area to dump */
  79         set_fs(USER_DS);
  80         if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
  81                 dump.u_dsize = 0;
  82         if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
  83                 dump.u_ssize = 0;
  84
  85         set_fs(KERNEL_DS);
  86 /* struct user */
  87         if (!dump_emit(cprm, &dump, sizeof(dump)))
  88                 goto end_coredump;
  89 /* Now dump all of the user data.  Include malloced stuff as well */
  90         if (!dump_skip(cprm, PAGE_SIZE - sizeof(dump)))
  91                 goto end_coredump;
  92 /* now we start writing out the user space info */
  93         set_fs(USER_DS);
  94 /* Dump the data area */
  95         if (dump.u_dsize != 0) {
  96                 dump_start = START_DATA(dump);
  97                 dump_size = dump.u_dsize << PAGE_SHIFT;
  98                 if (!dump_emit(cprm, dump_start, dump_size))
  99                         goto end_coredump;
 100         }
 101 /* Now prepare to dump the stack area */
 102         if (dump.u_ssize != 0) {
 103                 dump_start = START_STACK(dump);
 104                 dump_size = dump.u_ssize << PAGE_SHIFT;
 105                 if (!dump_emit(cprm, dump_start, dump_size))
 106                         goto end_coredump;
 107         }
 108 end_coredump:
 109         set_fs(fs);
 110         return has_dumped;
 111 }
 112 #else
 113 #define aout_core_dump NULL
 114 #endif
 115
 116 static struct linux_binfmt aout_format = {
 117         .module         = THIS_MODULE,
 118         .load_binary    = load_aout_binary,
 119         .load_shlib     = load_aout_library,
 120         .core_dump      = aout_core_dump,
 121         .min_coredump   = PAGE_SIZE
 122 };
 123
 124 #define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
 125
 126 static int set_brk(unsigned long start, unsigned long end)
 127 {
 128         start = PAGE_ALIGN(start);
 129         end = PAGE_ALIGN(end);
 130         if (end > start) {
 131                 unsigned long addr;
 132                 addr = vm_brk(start, end - start);
 133                 if (BAD_ADDR(addr))
 134                         return addr;
 135         }
 136         return 0;
 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)
 203 {
 204         struct pt_regs *regs = current_pt_regs();
 205         struct exec ex;
 206         unsigned long error;
 207         unsigned long fd_offset;
 208         unsigned long rlim;
 209         int retval;
 210
 211         ex = *((struct exec *) bprm->buf);              /* exec-header */
 212         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 213              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 214             N_TRSIZE(ex) || N_DRSIZE(ex) ||
 215             i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 216                 return -ENOEXEC;
 217         }
 218
 219         /*
 220          * Requires a mmap handler. This prevents people from using a.out
 221          * as part of an exploit attack against /proc-related vulnerabilities.
 222          */
 223         if (!bprm->file->f_op->mmap)
 224                 return -ENOEXEC;
 225
 226         fd_offset = N_TXTOFF(ex);
 227
 228         /* Check initial limits. This avoids letting people circumvent
 229          * size limits imposed on them by creating programs with large
 230          * arrays in the data or bss.
 231          */
 232         rlim = rlimit(RLIMIT_DATA);
 233         if (rlim >= RLIM_INFINITY)
 234                 rlim = ~0;
 235         if (ex.a_data + ex.a_bss > rlim)
 236                 return -ENOMEM;
 237
 238         /* Flush all traces of the currently running executable */
 239         retval = flush_old_exec(bprm);
 240         if (retval)
 241                 return retval;
 242
 243         /* OK, This is the point of no return */
 244 #ifdef __alpha__
 245         SET_AOUT_PERSONALITY(bprm, ex);
 246 #else
 247         set_personality(PER_LINUX);
 248 #endif
 249         setup_new_exec(bprm);
 250
 251         current->mm->end_code = ex.a_text +
 252                 (current->mm->start_code = N_TXTADDR(ex));
 253         current->mm->end_data = ex.a_data +
 254                 (current->mm->start_data = N_DATADDR(ex));
 255         current->mm->brk = ex.a_bss +
 256                 (current->mm->start_brk = N_BSSADDR(ex));
 257
 258         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 259         if (retval < 0)
 260                 return retval;
 261
 262         install_exec_creds(bprm);
 263
 264         if (N_MAGIC(ex) == OMAGIC) {
 265                 unsigned long text_addr, map_size;
 266                 loff_t pos;
 267
 268                 text_addr = N_TXTADDR(ex);
 269
 270 #ifdef __alpha__
 271                 pos = fd_offset;
 272                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 273 #else
 274                 pos = 32;
 275                 map_size = ex.a_text+ex.a_data;
 276 #endif
 277                 error = vm_brk(text_addr & PAGE_MASK, map_size);
 278                 if (error != (text_addr & PAGE_MASK))
 279                         return error;
 280
 281                 error = read_code(bprm->file, text_addr, pos,
 282                                   ex.a_text+ex.a_data);
 283                 if ((signed long)error < 0)
 284                         return error;
 285         } else {
 286                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 287                     (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
 288                 {
 289                         printk(KERN_NOTICE "executable not page aligned\n");
 290                 }
 291
 292                 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
 293                 {
 294                         printk(KERN_WARNING
 295                                "fd_offset is not page aligned. Please convert program: %pD\n",
 296                                bprm->file);
 297                 }
 298
 299                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 300                         vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 301                         read_code(bprm->file, N_TXTADDR(ex), fd_offset,
 302                                   ex.a_text + ex.a_data);
 303                         goto beyond_if;
 304                 }
 305
 306                 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 307                         PROT_READ | PROT_EXEC,
 308                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 309                         fd_offset);
 310
 311                 if (error != N_TXTADDR(ex))
 312                         return error;
 313
 314                 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 315                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 316                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 317                                 fd_offset + ex.a_text);
 318                 if (error != N_DATADDR(ex))
 319                         return error;
 320         }
 321 beyond_if:
 322         set_binfmt(&aout_format);
 323
 324         retval = set_brk(current->mm->start_brk, current->mm->brk);
 325         if (retval < 0)
 326                 return retval;
 327
 328         current->mm->start_stack =
 329                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 330 #ifdef __alpha__
 331         regs->gp = ex.a_gpvalue;
 332 #endif
 333         start_thread(regs, ex.a_entry, current->mm->start_stack);
 334         return 0;
 335 }
 336
 337 static int load_aout_library(struct file *file)
 338 {
 339         struct inode * inode;
 340         unsigned long bss, start_addr, len;
 341         unsigned long error;
 342         int retval;
 343         struct exec ex;
 344
 345         inode = file_inode(file);
 346
 347         retval = -ENOEXEC;
 348         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 349         if (error != sizeof(ex))
 350                 goto out;
 351
 352         /* We come in here for the regular a.out style of shared libraries */
 353         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 354             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 355             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 356                 goto out;
 357         }
 358
 359         /*
 360          * Requires a mmap handler. This prevents people from using a.out
 361          * as part of an exploit attack against /proc-related vulnerabilities.
 362          */
 363         if (!file->f_op->mmap)
 364                 goto out;
 365
 366         if (N_FLAGS(ex))
 367                 goto out;
 368
 369         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 370            this off to get the starting address for the page */
 371
 372         start_addr =  ex.a_entry & 0xfffff000;
 373
 374         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 375                 if (printk_ratelimit())
 376                 {
 377                         printk(KERN_WARNING
 378                                "N_TXTOFF is not page aligned. Please convert library: %pD\n",
 379                                file);
 380                 }
 381                 vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 382
 383                 read_code(file, start_addr, N_TXTOFF(ex),
 384                           ex.a_text + ex.a_data);
 385                 retval = 0;
 386                 goto out;
 387         }
 388         /* Now use mmap to map the library into memory. */
 389         error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
 390                         PROT_READ | PROT_WRITE | PROT_EXEC,
 391                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 392                         N_TXTOFF(ex));
 393         retval = error;
 394         if (error != start_addr)
 395                 goto out;
 396
 397         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 398         bss = ex.a_text + ex.a_data + ex.a_bss;
 399         if (bss > len) {
 400                 error = vm_brk(start_addr + len, bss - len);
 401                 retval = error;
 402                 if (error != start_addr + len)
 403                         goto out;
 404         }
 405         retval = 0;
 406 out:
 407         return retval;
 408 }
 409
 410 static int __init init_aout_binfmt(void)
 411 {
 412         register_binfmt(&aout_format);
 413         return 0;
 414 }
 415
 416 static void __exit exit_aout_binfmt(void)
 417 {
 418         unregister_binfmt(&aout_format);
 419 }
 420
 421 core_initcall(init_aout_binfmt);
 422 module_exit(exit_aout_binfmt);
 423 MODULE_LICENSE("GPL");