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 *, struct pt_regs * regs);
  34static int load_aout_library(struct file*);
  35static int aout_core_dump(struct coredump_params *cprm);
  36
  37static struct linux_binfmt aout_format = {
  38        .module         = THIS_MODULE,
  39        .load_binary    = load_aout_binary,
  40        .load_shlib     = load_aout_library,
  41        .core_dump      = aout_core_dump,
  42        .min_coredump   = PAGE_SIZE
  43};
  44
  45#define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
  46
  47static int set_brk(unsigned long start, unsigned long end)
  48{
  49        start = PAGE_ALIGN(start);
  50        end = PAGE_ALIGN(end);
  51        if (end > start) {
  52                unsigned long addr;
  53                addr = vm_brk(start, end - start);
  54                if (BAD_ADDR(addr))
  55                        return addr;
  56        }
  57        return 0;
  58}
  59
  60/*
  61 * Routine writes a core dump image in the current directory.
  62 * Currently only a stub-function.
  63 *
  64 * Note that setuid/setgid files won't make a core-dump if the uid/gid
  65 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
  66 * field, which also makes sure the core-dumps won't be recursive if the
  67 * dumping of the process results in another error..
  68 */
  69
  70static int aout_core_dump(struct coredump_params *cprm)
  71{
  72        struct file *file = cprm->file;
  73        mm_segment_t fs;
  74        int has_dumped = 0;
  75        void __user *dump_start;
  76        int dump_size;
  77        struct user dump;
  78#ifdef __alpha__
  79#       define START_DATA(u)    ((void __user *)u.start_data)
  80#else
  81#       define START_DATA(u)    ((void __user *)((u.u_tsize << PAGE_SHIFT) + \
  82                                 u.start_code))
  83#endif
  84#       define START_STACK(u)   ((void __user *)u.start_stack)
  85
  86        fs = get_fs();
  87        set_fs(KERNEL_DS);
  88        has_dumped = 1;
  89        current->flags |= PF_DUMPCORE;
  90        strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
  91        dump.u_ar0 = offsetof(struct user, regs);
  92        dump.signal = cprm->signr;
  93        aout_dump_thread(cprm->regs, &dump);
  94
  95/* If the size of the dump file exceeds the rlimit, then see what would happen
  96   if we wrote the stack, but not the data area.  */
  97        if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
  98                dump.u_dsize = 0;
  99
 100/* Make sure we have enough room to write the stack and data areas. */
 101        if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
 102                dump.u_ssize = 0;
 103
 104/* make sure we actually have a data and stack area to dump */
 105        set_fs(USER_DS);
 106        if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
 107                dump.u_dsize = 0;
 108        if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
 109                dump.u_ssize = 0;
 110
 111        set_fs(KERNEL_DS);
 112/* struct user */
 113        if (!dump_write(file, &dump, sizeof(dump)))
 114                goto end_coredump;
 115/* Now dump all of the user data.  Include malloced stuff as well */
 116        if (!dump_seek(cprm->file, PAGE_SIZE - sizeof(dump)))
 117                goto end_coredump;
 118/* now we start writing out the user space info */
 119        set_fs(USER_DS);
 120/* Dump the data area */
 121        if (dump.u_dsize != 0) {
 122                dump_start = START_DATA(dump);
 123                dump_size = dump.u_dsize << PAGE_SHIFT;
 124                if (!dump_write(file, dump_start, dump_size))
 125                        goto end_coredump;
 126        }
 127/* Now prepare to dump the stack area */
 128        if (dump.u_ssize != 0) {
 129                dump_start = START_STACK(dump);
 130                dump_size = dump.u_ssize << PAGE_SHIFT;
 131                if (!dump_write(file, dump_start, dump_size))
 132                        goto end_coredump;
 133        }
 134end_coredump:
 135        set_fs(fs);
 136        return has_dumped;
 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 */
 144static 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
 202static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 203{
 204        struct exec ex;
 205        unsigned long error;
 206        unsigned long fd_offset;
 207        unsigned long rlim;
 208        int retval;
 209
 210        ex = *((struct exec *) bprm->buf);              /* exec-header */
 211        if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 212             N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 213            N_TRSIZE(ex) || N_DRSIZE(ex) ||
 214            i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 215                return -ENOEXEC;
 216        }
 217
 218        /*
 219         * Requires a mmap handler. This prevents people from using a.out
 220         * as part of an exploit attack against /proc-related vulnerabilities.
 221         */
 222        if (!bprm->file->f_op || !bprm->file->f_op->mmap)
 223                return -ENOEXEC;
 224
 225        fd_offset = N_TXTOFF(ex);
 226
 227        /* Check initial limits. This avoids letting people circumvent
 228         * size limits imposed on them by creating programs with large
 229         * arrays in the data or bss.
 230         */
 231        rlim = rlimit(RLIMIT_DATA);
 232        if (rlim >= RLIM_INFINITY)
 233                rlim = ~0;
 234        if (ex.a_data + ex.a_bss > rlim)
 235                return -ENOMEM;
 236
 237        /* Flush all traces of the currently running executable */
 238        retval = flush_old_exec(bprm);
 239        if (retval)
 240                return retval;
 241
 242        /* OK, This is the point of no return */
 243#ifdef __alpha__
 244        SET_AOUT_PERSONALITY(bprm, ex);
 245#else
 246        set_personality(PER_LINUX);
 247#endif
 248        setup_new_exec(bprm);
 249
 250        current->mm->end_code = ex.a_text +
 251                (current->mm->start_code = N_TXTADDR(ex));
 252        current->mm->end_data = ex.a_data +
 253                (current->mm->start_data = N_DATADDR(ex));
 254        current->mm->brk = ex.a_bss +
 255                (current->mm->start_brk = N_BSSADDR(ex));
 256        current->mm->free_area_cache = current->mm->mmap_base;
 257        current->mm->cached_hole_size = 0;
 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 = bprm->file->f_op->read(bprm->file,
 288                          (char __user *)text_addr,
 289                          ex.a_text+ex.a_data, &pos);
 290                if ((signed long)error < 0) {
 291                        send_sig(SIGKILL, current, 0);
 292                        return error;
 293                }
 294                         
 295                flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
 296        } else {
 297                if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 298                    (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
 299                {
 300                        printk(KERN_NOTICE "executable not page aligned\n");
 301                }
 302
 303                if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
 304                {
 305                        printk(KERN_WARNING 
 306                               "fd_offset is not page aligned. Please convert program: %s\n",
 307                               bprm->file->f_path.dentry->d_name.name);
 308                }
 309
 310                if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 311                        loff_t pos = fd_offset;
 312                        vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 313                        bprm->file->f_op->read(bprm->file,
 314                                        (char __user *)N_TXTADDR(ex),
 315                                        ex.a_text+ex.a_data, &pos);
 316                        flush_icache_range((unsigned long) N_TXTADDR(ex),
 317                                           (unsigned long) N_TXTADDR(ex) +
 318                                           ex.a_text+ex.a_data);
 319                        goto beyond_if;
 320                }
 321
 322                error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 323                        PROT_READ | PROT_EXEC,
 324                        MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 325                        fd_offset);
 326
 327                if (error != N_TXTADDR(ex)) {
 328                        send_sig(SIGKILL, current, 0);
 329                        return error;
 330                }
 331
 332                error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 333                                PROT_READ | PROT_WRITE | PROT_EXEC,
 334                                MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 335                                fd_offset + ex.a_text);
 336                if (error != N_DATADDR(ex)) {
 337                        send_sig(SIGKILL, current, 0);
 338                        return error;
 339                }
 340        }
 341beyond_if:
 342        set_binfmt(&aout_format);
 343
 344        retval = set_brk(current->mm->start_brk, current->mm->brk);
 345        if (retval < 0) {
 346                send_sig(SIGKILL, current, 0);
 347                return retval;
 348        }
 349
 350        current->mm->start_stack =
 351                (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 352#ifdef __alpha__
 353        regs->gp = ex.a_gpvalue;
 354#endif
 355        start_thread(regs, ex.a_entry, current->mm->start_stack);
 356        return 0;
 357}
 358
 359static int load_aout_library(struct file *file)
 360{
 361        struct inode * inode;
 362        unsigned long bss, start_addr, len;
 363        unsigned long error;
 364        int retval;
 365        struct exec ex;
 366
 367        inode = file->f_path.dentry->d_inode;
 368
 369        retval = -ENOEXEC;
 370        error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 371        if (error != sizeof(ex))
 372                goto out;
 373
 374        /* We come in here for the regular a.out style of shared libraries */
 375        if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 376            N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 377            i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 378                goto out;
 379        }
 380
 381        /*
 382         * Requires a mmap handler. This prevents people from using a.out
 383         * as part of an exploit attack against /proc-related vulnerabilities.
 384         */
 385        if (!file->f_op || !file->f_op->mmap)
 386                goto out;
 387
 388        if (N_FLAGS(ex))
 389                goto out;
 390
 391        /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 392           this off to get the starting address for the page */
 393
 394        start_addr =  ex.a_entry & 0xfffff000;
 395
 396        if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 397                loff_t pos = N_TXTOFF(ex);
 398
 399                if (printk_ratelimit())
 400                {
 401                        printk(KERN_WARNING 
 402                               "N_TXTOFF is not page aligned. Please convert library: %s\n",
 403                               file->f_path.dentry->d_name.name);
 404                }
 405                vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 406                
 407                file->f_op->read(file, (char __user *)start_addr,
 408                        ex.a_text + ex.a_data, &pos);
 409                flush_icache_range((unsigned long) start_addr,
 410                                   (unsigned long) start_addr + ex.a_text + ex.a_data);
 411
 412                retval = 0;
 413                goto out;
 414        }
 415        /* Now use mmap to map the library into memory. */
 416        error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
 417                        PROT_READ | PROT_WRITE | PROT_EXEC,
 418                        MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 419                        N_TXTOFF(ex));
 420        retval = error;
 421        if (error != start_addr)
 422                goto out;
 423
 424        len = PAGE_ALIGN(ex.a_text + ex.a_data);
 425        bss = ex.a_text + ex.a_data + ex.a_bss;
 426        if (bss > len) {
 427                error = vm_brk(start_addr + len, bss - len);
 428                retval = error;
 429                if (error != start_addr + len)
 430                        goto out;
 431        }
 432        retval = 0;
 433out:
 434        return retval;
 435}
 436
 437static int __init init_aout_binfmt(void)
 438{
 439        register_binfmt(&aout_format);
 440        return 0;
 441}
 442
 443static void __exit exit_aout_binfmt(void)
 444{
 445        unregister_binfmt(&aout_format);
 446}
 447
 448core_initcall(init_aout_binfmt);
 449module_exit(exit_aout_binfmt);
 450MODULE_LICENSE("GPL");
 451
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