linux/fs/binfmt_aout.c
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   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
  34static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
  35static int load_aout_library(struct file*);
  36static int aout_core_dump(struct coredump_params *cprm);
  37
  38static 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
  48static 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
  73static 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        }
 137end_coredump:
 138        set_fs(fs);
 139        return has_dumped;
 140}
 141
 142/*
 143 * create_aout_tables() parses the env- and arg-strings in new user
 144 * memory and creates the pointer tables from them, and puts their
 145 * addresses on the "stack", returning the new stack pointer value.
 146 */
 147static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
 148{
 149        char __user * __user *argv;
 150        char __user * __user *envp;
 151        unsigned long __user *sp;
 152        int argc = bprm->argc;
 153        int envc = bprm->envc;
 154
 155        sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
 156#ifdef __alpha__
 157/* whee.. test-programs are so much fun. */
 158        put_user(0, --sp);
 159        put_user(0, --sp);
 160        if (bprm->loader) {
 161                put_user(0, --sp);
 162                put_user(1003, --sp);
 163                put_user(bprm->loader, --sp);
 164                put_user(1002, --sp);
 165        }
 166        put_user(bprm->exec, --sp);
 167        put_user(1001, --sp);
 168#endif
 169        sp -= envc+1;
 170        envp = (char __user * __user *) sp;
 171        sp -= argc+1;
 172        argv = (char __user * __user *) sp;
 173#ifndef __alpha__
 174        put_user((unsigned long) envp,--sp);
 175        put_user((unsigned long) argv,--sp);
 176#endif
 177        put_user(argc,--sp);
 178        current->mm->arg_start = (unsigned long) p;
 179        while (argc-->0) {
 180                char c;
 181                put_user(p,argv++);
 182                do {
 183                        get_user(c,p++);
 184                } while (c);
 185        }
 186        put_user(NULL,argv);
 187        current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 188        while (envc-->0) {
 189                char c;
 190                put_user(p,envp++);
 191                do {
 192                        get_user(c,p++);
 193                } while (c);
 194        }
 195        put_user(NULL,envp);
 196        current->mm->env_end = (unsigned long) p;
 197        return sp;
 198}
 199
 200/*
 201 * These are the functions used to load a.out style executables and shared
 202 * libraries.  There is no binary dependent code anywhere else.
 203 */
 204
 205static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 206{
 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(bprm->file->f_path.dentry->d_inode) < 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        install_exec_creds(bprm);
 263        current->flags &= ~PF_FORKNOEXEC;
 264
 265        if (N_MAGIC(ex) == OMAGIC) {
 266                unsigned long text_addr, map_size;
 267                loff_t pos;
 268
 269                text_addr = N_TXTADDR(ex);
 270
 271#ifdef __alpha__
 272                pos = fd_offset;
 273                map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 274#else
 275                pos = 32;
 276                map_size = ex.a_text+ex.a_data;
 277#endif
 278                down_write(&current->mm->mmap_sem);
 279                error = do_brk(text_addr & PAGE_MASK, map_size);
 280                up_write(&current->mm->mmap_sem);
 281                if (error != (text_addr & PAGE_MASK)) {
 282                        send_sig(SIGKILL, current, 0);
 283                        return error;
 284                }
 285
 286                error = bprm->file->f_op->read(bprm->file,
 287                          (char __user *)text_addr,
 288                          ex.a_text+ex.a_data, &pos);
 289                if ((signed long)error < 0) {
 290                        send_sig(SIGKILL, current, 0);
 291                        return error;
 292                }
 293                         
 294                flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
 295        } else {
 296                if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 297                    (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
 298                {
 299                        printk(KERN_NOTICE "executable not page aligned\n");
 300                }
 301
 302                if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
 303                {
 304                        printk(KERN_WARNING 
 305                               "fd_offset is not page aligned. Please convert program: %s\n",
 306                               bprm->file->f_path.dentry->d_name.name);
 307                }
 308
 309                if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 310                        loff_t pos = fd_offset;
 311                        down_write(&current->mm->mmap_sem);
 312                        do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 313                        up_write(&current->mm->mmap_sem);
 314                        bprm->file->f_op->read(bprm->file,
 315                                        (char __user *)N_TXTADDR(ex),
 316                                        ex.a_text+ex.a_data, &pos);
 317                        flush_icache_range((unsigned long) N_TXTADDR(ex),
 318                                           (unsigned long) N_TXTADDR(ex) +
 319                                           ex.a_text+ex.a_data);
 320                        goto beyond_if;
 321                }
 322
 323                down_write(&current->mm->mmap_sem);
 324                error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 325                        PROT_READ | PROT_EXEC,
 326                        MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 327                        fd_offset);
 328                up_write(&current->mm->mmap_sem);
 329
 330                if (error != N_TXTADDR(ex)) {
 331                        send_sig(SIGKILL, current, 0);
 332                        return error;
 333                }
 334
 335                down_write(&current->mm->mmap_sem);
 336                error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 337                                PROT_READ | PROT_WRITE | PROT_EXEC,
 338                                MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 339                                fd_offset + ex.a_text);
 340                up_write(&current->mm->mmap_sem);
 341                if (error != N_DATADDR(ex)) {
 342                        send_sig(SIGKILL, current, 0);
 343                        return error;
 344                }
 345        }
 346beyond_if:
 347        set_binfmt(&aout_format);
 348
 349        retval = set_brk(current->mm->start_brk, current->mm->brk);
 350        if (retval < 0) {
 351                send_sig(SIGKILL, current, 0);
 352                return retval;
 353        }
 354
 355        retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 356        if (retval < 0) { 
 357                /* Someone check-me: is this error path enough? */ 
 358                send_sig(SIGKILL, current, 0); 
 359                return retval;
 360        }
 361
 362        current->mm->start_stack =
 363                (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 364#ifdef __alpha__
 365        regs->gp = ex.a_gpvalue;
 366#endif
 367        start_thread(regs, ex.a_entry, current->mm->start_stack);
 368        return 0;
 369}
 370
 371static int load_aout_library(struct file *file)
 372{
 373        struct inode * inode;
 374        unsigned long bss, start_addr, len;
 375        unsigned long error;
 376        int retval;
 377        struct exec ex;
 378
 379        inode = file->f_path.dentry->d_inode;
 380
 381        retval = -ENOEXEC;
 382        error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 383        if (error != sizeof(ex))
 384                goto out;
 385
 386        /* We come in here for the regular a.out style of shared libraries */
 387        if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 388            N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 389            i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 390                goto out;
 391        }
 392
 393        /*
 394         * Requires a mmap handler. This prevents people from using a.out
 395         * as part of an exploit attack against /proc-related vulnerabilities.
 396         */
 397        if (!file->f_op || !file->f_op->mmap)
 398                goto out;
 399
 400        if (N_FLAGS(ex))
 401                goto out;
 402
 403        /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 404           this off to get the starting address for the page */
 405
 406        start_addr =  ex.a_entry & 0xfffff000;
 407
 408        if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 409                loff_t pos = N_TXTOFF(ex);
 410
 411                if (printk_ratelimit())
 412                {
 413                        printk(KERN_WARNING 
 414                               "N_TXTOFF is not page aligned. Please convert library: %s\n",
 415                               file->f_path.dentry->d_name.name);
 416                }
 417                down_write(&current->mm->mmap_sem);
 418                do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 419                up_write(&current->mm->mmap_sem);
 420                
 421                file->f_op->read(file, (char __user *)start_addr,
 422                        ex.a_text + ex.a_data, &pos);
 423                flush_icache_range((unsigned long) start_addr,
 424                                   (unsigned long) start_addr + ex.a_text + ex.a_data);
 425
 426                retval = 0;
 427                goto out;
 428        }
 429        /* Now use mmap to map the library into memory. */
 430        down_write(&current->mm->mmap_sem);
 431        error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
 432                        PROT_READ | PROT_WRITE | PROT_EXEC,
 433                        MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 434                        N_TXTOFF(ex));
 435        up_write(&current->mm->mmap_sem);
 436        retval = error;
 437        if (error != start_addr)
 438                goto out;
 439
 440        len = PAGE_ALIGN(ex.a_text + ex.a_data);
 441        bss = ex.a_text + ex.a_data + ex.a_bss;
 442        if (bss > len) {
 443                down_write(&current->mm->mmap_sem);
 444                error = do_brk(start_addr + len, bss - len);
 445                up_write(&current->mm->mmap_sem);
 446                retval = error;
 447                if (error != start_addr + len)
 448                        goto out;
 449        }
 450        retval = 0;
 451out:
 452        return retval;
 453}
 454
 455static int __init init_aout_binfmt(void)
 456{
 457        return register_binfmt(&aout_format);
 458}
 459
 460static void __exit exit_aout_binfmt(void)
 461{
 462        unregister_binfmt(&aout_format);
 463}
 464
 465core_initcall(init_aout_binfmt);
 466module_exit(exit_aout_binfmt);
 467MODULE_LICENSE("GPL");
 468
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