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        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        }
 110end_coredump:
 111        set_fs(fs);
 112        return has_dumped;
 113}
 114#else
 115#define aout_core_dump NULL
 116#endif
 117
 118static 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
 128static 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 */
 146static 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
 204static 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(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        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        }
 344beyond_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
 362static 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->f_path.dentry->d_inode;
 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;
 436out:
 437        return retval;
 438}
 439
 440static int __init init_aout_binfmt(void)
 441{
 442        register_binfmt(&aout_format);
 443        return 0;
 444}
 445
 446static void __exit exit_aout_binfmt(void)
 447{
 448        unregister_binfmt(&aout_format);
 449}
 450
 451core_initcall(init_aout_binfmt);
 452module_exit(exit_aout_binfmt);
 453MODULE_LICENSE("GPL");
 454
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