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/uaccess.h>
  30#include <asm/cacheflush.h>
  31#include <asm/a.out-core.h>
  32
  33static int load_aout_binary(struct linux_binprm *);
  34static 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 */
  46static 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        }
 109end_coredump:
 110        set_fs(fs);
 111        return has_dumped;
 112}
 113#else
 114#define aout_core_dump NULL
 115#endif
 116
 117static 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
 127static 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 */
 145static 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
 203static 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        current->mm->free_area_cache = current->mm->mmap_base;
 259        current->mm->cached_hole_size = 0;
 260
 261        retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 262        if (retval < 0) {
 263                /* Someone check-me: is this error path enough? */
 264                send_sig(SIGKILL, current, 0);
 265                return retval;
 266        }
 267
 268        install_exec_creds(bprm);
 269
 270        if (N_MAGIC(ex) == OMAGIC) {
 271                unsigned long text_addr, map_size;
 272                loff_t pos;
 273
 274                text_addr = N_TXTADDR(ex);
 275
 276#ifdef __alpha__
 277                pos = fd_offset;
 278                map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 279#else
 280                pos = 32;
 281                map_size = ex.a_text+ex.a_data;
 282#endif
 283                error = vm_brk(text_addr & PAGE_MASK, map_size);
 284                if (error != (text_addr & PAGE_MASK)) {
 285                        send_sig(SIGKILL, current, 0);
 286                        return error;
 287                }
 288
 289                error = read_code(bprm->file, text_addr, pos,
 290                                  ex.a_text+ex.a_data);
 291                if ((signed long)error < 0) {
 292                        send_sig(SIGKILL, current, 0);
 293                        return error;
 294                }
 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                        vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 311                        read_code(bprm->file, N_TXTADDR(ex), fd_offset,
 312                                  ex.a_text + ex.a_data);
 313                        goto beyond_if;
 314                }
 315
 316                error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 317                        PROT_READ | PROT_EXEC,
 318                        MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 319                        fd_offset);
 320
 321                if (error != N_TXTADDR(ex)) {
 322                        send_sig(SIGKILL, current, 0);
 323                        return error;
 324                }
 325
 326                error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 327                                PROT_READ | PROT_WRITE | PROT_EXEC,
 328                                MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 329                                fd_offset + ex.a_text);
 330                if (error != N_DATADDR(ex)) {
 331                        send_sig(SIGKILL, current, 0);
 332                        return error;
 333                }
 334        }
 335beyond_if:
 336        set_binfmt(&aout_format);
 337
 338        retval = set_brk(current->mm->start_brk, current->mm->brk);
 339        if (retval < 0) {
 340                send_sig(SIGKILL, current, 0);
 341                return retval;
 342        }
 343
 344        current->mm->start_stack =
 345                (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 346#ifdef __alpha__
 347        regs->gp = ex.a_gpvalue;
 348#endif
 349        start_thread(regs, ex.a_entry, current->mm->start_stack);
 350        return 0;
 351}
 352
 353static int load_aout_library(struct file *file)
 354{
 355        struct inode * inode;
 356        unsigned long bss, start_addr, len;
 357        unsigned long error;
 358        int retval;
 359        struct exec ex;
 360
 361        inode = file_inode(file);
 362
 363        retval = -ENOEXEC;
 364        error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 365        if (error != sizeof(ex))
 366                goto out;
 367
 368        /* We come in here for the regular a.out style of shared libraries */
 369        if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 370            N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 371            i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 372                goto out;
 373        }
 374
 375        /*
 376         * Requires a mmap handler. This prevents people from using a.out
 377         * as part of an exploit attack against /proc-related vulnerabilities.
 378         */
 379        if (!file->f_op || !file->f_op->mmap)
 380                goto out;
 381
 382        if (N_FLAGS(ex))
 383                goto out;
 384
 385        /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 386           this off to get the starting address for the page */
 387
 388        start_addr =  ex.a_entry & 0xfffff000;
 389
 390        if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 391                if (printk_ratelimit())
 392                {
 393                        printk(KERN_WARNING 
 394                               "N_TXTOFF is not page aligned. Please convert library: %s\n",
 395                               file->f_path.dentry->d_name.name);
 396                }
 397                vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 398                
 399                read_code(file, start_addr, N_TXTOFF(ex),
 400                          ex.a_text + ex.a_data);
 401                retval = 0;
 402                goto out;
 403        }
 404        /* Now use mmap to map the library into memory. */
 405        error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
 406                        PROT_READ | PROT_WRITE | PROT_EXEC,
 407                        MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 408                        N_TXTOFF(ex));
 409        retval = error;
 410        if (error != start_addr)
 411                goto out;
 412
 413        len = PAGE_ALIGN(ex.a_text + ex.a_data);
 414        bss = ex.a_text + ex.a_data + ex.a_bss;
 415        if (bss > len) {
 416                error = vm_brk(start_addr + len, bss - len);
 417                retval = error;
 418                if (error != start_addr + len)
 419                        goto out;
 420        }
 421        retval = 0;
 422out:
 423        return retval;
 424}
 425
 426static int __init init_aout_binfmt(void)
 427{
 428        register_binfmt(&aout_format);
 429        return 0;
 430}
 431
 432static void __exit exit_aout_binfmt(void)
 433{
 434        unregister_binfmt(&aout_format);
 435}
 436
 437core_initcall(init_aout_binfmt);
 438module_exit(exit_aout_binfmt);
 439MODULE_LICENSE("GPL");
 440
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