LXR linux/fs/binfmt

   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/slab.h>
  24#include <linux/binfmts.h>
  25#include <linux/personality.h>
  26#include <linux/init.h>
  27
  28#include <asm/system.h>
  29#include <asm/uaccess.h>
  30#include <asm/cacheflush.h>
  31
  32static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
  33static int load_aout_library(struct file*);
  34static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file);
  35
  36static struct linux_binfmt aout_format = {
  37        .module         = THIS_MODULE,
  38        .load_binary    = load_aout_binary,
  39        .load_shlib     = load_aout_library,
  40        .core_dump      = aout_core_dump,
  41        .min_coredump   = PAGE_SIZE
  42};
  43
  44#define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
  45
  46static int set_brk(unsigned long start, unsigned long end)
  47{
  48        start = PAGE_ALIGN(start);
  49        end = PAGE_ALIGN(end);
  50        if (end > start) {
  51                unsigned long addr;
  52                down_write(&current->mm->mmap_sem);
  53                addr = do_brk(start, end - start);
  54                up_write(&current->mm->mmap_sem);
  55                if (BAD_ADDR(addr))
  56                        return addr;
  57        }
  58        return 0;
  59}
  60
  61/*
  62 * These are the only things you should do on a core-file: use only these
  63 * macros to write out all the necessary info.
  64 */
  65
  66static int dump_write(struct file *file, const void *addr, int nr)
  67{
  68        return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
  69}
  70
  71#define DUMP_WRITE(addr, nr)    \
  72        if (!dump_write(file, (void *)(addr), (nr))) \
  73                goto end_coredump;
  74
  75#define DUMP_SEEK(offset) \
  76if (file->f_op->llseek) { \
  77        if (file->f_op->llseek(file,(offset),0) != (offset)) \
  78                goto end_coredump; \
  79} else file->f_pos = (offset)
  80
  81/*
  82 * Routine writes a core dump image in the current directory.
  83 * Currently only a stub-function.
  84 *
  85 * Note that setuid/setgid files won't make a core-dump if the uid/gid
  86 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
  87 * field, which also makes sure the core-dumps won't be recursive if the
  88 * dumping of the process results in another error..
  89 */
  90
  91static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file)
  92{
  93        mm_segment_t fs;
  94        int has_dumped = 0;
  95        unsigned long dump_start, dump_size;
  96        struct user dump;
  97#if defined(__alpha__)
  98#       define START_DATA(u)    (u.start_data)
  99#elif defined(__arm__)
 100#       define START_DATA(u)    ((u.u_tsize << PAGE_SHIFT) + u.start_code)
 101#elif defined(__sparc__)
 102#       define START_DATA(u)    (u.u_tsize)
 103#elif defined(__i386__) || defined(__mc68000__) || defined(__arch_um__)
 104#       define START_DATA(u)    (u.u_tsize << PAGE_SHIFT)
 105#endif
 106#ifdef __sparc__
 107#       define START_STACK(u)   ((regs->u_regs[UREG_FP]) & ~(PAGE_SIZE - 1))
 108#else
 109#       define START_STACK(u)   (u.start_stack)
 110#endif
 111
 112        fs = get_fs();
 113        set_fs(KERNEL_DS);
 114        has_dumped = 1;
 115        current->flags |= PF_DUMPCORE;
 116        strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
 117#ifndef __sparc__
 118        dump.u_ar0 = (void *)(((unsigned long)(&dump.regs)) - ((unsigned long)(&dump)));
 119#endif
 120        dump.signal = signr;
 121        dump_thread(regs, &dump);
 122
 123/* If the size of the dump file exceeds the rlimit, then see what would happen
 124   if we wrote the stack, but not the data area.  */
 125#ifdef __sparc__
 126        if ((dump.u_dsize+dump.u_ssize) >
 127            current->signal->rlim[RLIMIT_CORE].rlim_cur)
 128                dump.u_dsize = 0;
 129#else
 130        if ((dump.u_dsize+dump.u_ssize+1) * PAGE_SIZE >
 131            current->signal->rlim[RLIMIT_CORE].rlim_cur)
 132                dump.u_dsize = 0;
 133#endif
 134
 135/* Make sure we have enough room to write the stack and data areas. */
 136#ifdef __sparc__
 137        if ((dump.u_ssize) >
 138            current->signal->rlim[RLIMIT_CORE].rlim_cur)
 139                dump.u_ssize = 0;
 140#else
 141        if ((dump.u_ssize+1) * PAGE_SIZE >
 142            current->signal->rlim[RLIMIT_CORE].rlim_cur)
 143                dump.u_ssize = 0;
 144#endif
 145
 146/* make sure we actually have a data and stack area to dump */
 147        set_fs(USER_DS);
 148#ifdef __sparc__
 149        if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize))
 150                dump.u_dsize = 0;
 151        if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize))
 152                dump.u_ssize = 0;
 153#else
 154        if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
 155                dump.u_dsize = 0;
 156        if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
 157                dump.u_ssize = 0;
 158#endif
 159
 160        set_fs(KERNEL_DS);
 161/* struct user */
 162        DUMP_WRITE(&dump,sizeof(dump));
 163/* Now dump all of the user data.  Include malloced stuff as well */
 164#ifndef __sparc__
 165        DUMP_SEEK(PAGE_SIZE);
 166#endif
 167/* now we start writing out the user space info */
 168        set_fs(USER_DS);
 169/* Dump the data area */
 170        if (dump.u_dsize != 0) {
 171                dump_start = START_DATA(dump);
 172#ifdef __sparc__
 173                dump_size = dump.u_dsize;
 174#else
 175                dump_size = dump.u_dsize << PAGE_SHIFT;
 176#endif
 177                DUMP_WRITE(dump_start,dump_size);
 178        }
 179/* Now prepare to dump the stack area */
 180        if (dump.u_ssize != 0) {
 181                dump_start = START_STACK(dump);
 182#ifdef __sparc__
 183                dump_size = dump.u_ssize;
 184#else
 185                dump_size = dump.u_ssize << PAGE_SHIFT;
 186#endif
 187                DUMP_WRITE(dump_start,dump_size);
 188        }
 189/* Finally dump the task struct.  Not be used by gdb, but could be useful */
 190        set_fs(KERNEL_DS);
 191        DUMP_WRITE(current,sizeof(*current));
 192end_coredump:
 193        set_fs(fs);
 194        return has_dumped;
 195}
 196
 197/*
 198 * create_aout_tables() parses the env- and arg-strings in new user
 199 * memory and creates the pointer tables from them, and puts their
 200 * addresses on the "stack", returning the new stack pointer value.
 201 */
 202static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
 203{
 204        char __user * __user *argv;
 205        char __user * __user *envp;
 206        unsigned long __user *sp;
 207        int argc = bprm->argc;
 208        int envc = bprm->envc;
 209
 210        sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
 211#ifdef __sparc__
 212        /* This imposes the proper stack alignment for a new process. */
 213        sp = (void __user *) (((unsigned long) sp) & ~7);
 214        if ((envc+argc+3)&1) --sp;
 215#endif
 216#ifdef __alpha__
 217/* whee.. test-programs are so much fun. */
 218        put_user(0, --sp);
 219        put_user(0, --sp);
 220        if (bprm->loader) {
 221                put_user(0, --sp);
 222                put_user(0x3eb, --sp);
 223                put_user(bprm->loader, --sp);
 224                put_user(0x3ea, --sp);
 225        }
 226        put_user(bprm->exec, --sp);
 227        put_user(0x3e9, --sp);
 228#endif
 229        sp -= envc+1;
 230        envp = (char __user * __user *) sp;
 231        sp -= argc+1;
 232        argv = (char __user * __user *) sp;
 233#if defined(__i386__) || defined(__mc68000__) || defined(__arm__) || defined(__arch_um__)
 234        put_user((unsigned long) envp,--sp);
 235        put_user((unsigned long) argv,--sp);
 236#endif
 237        put_user(argc,--sp);
 238        current->mm->arg_start = (unsigned long) p;
 239        while (argc-->0) {
 240                char c;
 241                put_user(p,argv++);
 242                do {
 243                        get_user(c,p++);
 244                } while (c);
 245        }
 246        put_user(NULL,argv);
 247        current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 248        while (envc-->0) {
 249                char c;
 250                put_user(p,envp++);
 251                do {
 252                        get_user(c,p++);
 253                } while (c);
 254        }
 255        put_user(NULL,envp);
 256        current->mm->env_end = (unsigned long) p;
 257        return sp;
 258}
 259
 260/*
 261 * These are the functions used to load a.out style executables and shared
 262 * libraries.  There is no binary dependent code anywhere else.
 263 */
 264
 265static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 266{
 267        struct exec ex;
 268        unsigned long error;
 269        unsigned long fd_offset;
 270        unsigned long rlim;
 271        int retval;
 272
 273        ex = *((struct exec *) bprm->buf);              /* exec-header */
 274        if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
 275             N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
 276            N_TRSIZE(ex) || N_DRSIZE(ex) ||
 277            i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 278                return -ENOEXEC;
 279        }
 280
 281        /*
 282         * Requires a mmap handler. This prevents people from using a.out
 283         * as part of an exploit attack against /proc-related vulnerabilities.
 284         */
 285        if (!bprm->file->f_op || !bprm->file->f_op->mmap)
 286                return -ENOEXEC;
 287
 288        fd_offset = N_TXTOFF(ex);
 289
 290        /* Check initial limits. This avoids letting people circumvent
 291         * size limits imposed on them by creating programs with large
 292         * arrays in the data or bss.
 293         */
 294        rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
 295        if (rlim >= RLIM_INFINITY)
 296                rlim = ~0;
 297        if (ex.a_data + ex.a_bss > rlim)
 298                return -ENOMEM;
 299
 300        /* Flush all traces of the currently running executable */
 301        retval = flush_old_exec(bprm);
 302        if (retval)
 303                return retval;
 304
 305        /* OK, This is the point of no return */
 306#if defined(__alpha__)
 307        SET_AOUT_PERSONALITY(bprm, ex);
 308#elif defined(__sparc__)
 309        set_personality(PER_SUNOS);
 310#if !defined(__sparc_v9__)
 311        memcpy(&current->thread.core_exec, &ex, sizeof(struct exec));
 312#endif
 313#else
 314        set_personality(PER_LINUX);
 315#endif
 316
 317        current->mm->end_code = ex.a_text +
 318                (current->mm->start_code = N_TXTADDR(ex));
 319        current->mm->end_data = ex.a_data +
 320                (current->mm->start_data = N_DATADDR(ex));
 321        current->mm->brk = ex.a_bss +
 322                (current->mm->start_brk = N_BSSADDR(ex));
 323        current->mm->free_area_cache = current->mm->mmap_base;
 324        current->mm->cached_hole_size = 0;
 325
 326        current->mm->mmap = NULL;
 327        compute_creds(bprm);
 328        current->flags &= ~PF_FORKNOEXEC;
 329#ifdef __sparc__
 330        if (N_MAGIC(ex) == NMAGIC) {
 331                loff_t pos = fd_offset;
 332                /* Fuck me plenty... */
 333                /* <AOL></AOL> */
 334                down_write(&current->mm->mmap_sem);     
 335                error = do_brk(N_TXTADDR(ex), ex.a_text);
 336                up_write(&current->mm->mmap_sem);
 337                bprm->file->f_op->read(bprm->file, (char *) N_TXTADDR(ex),
 338                          ex.a_text, &pos);
 339                down_write(&current->mm->mmap_sem);
 340                error = do_brk(N_DATADDR(ex), ex.a_data);
 341                up_write(&current->mm->mmap_sem);
 342                bprm->file->f_op->read(bprm->file, (char *) N_DATADDR(ex),
 343                          ex.a_data, &pos);
 344                goto beyond_if;
 345        }
 346#endif
 347
 348        if (N_MAGIC(ex) == OMAGIC) {
 349                unsigned long text_addr, map_size;
 350                loff_t pos;
 351
 352                text_addr = N_TXTADDR(ex);
 353
 354#if defined(__alpha__) || defined(__sparc__)
 355                pos = fd_offset;
 356                map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
 357#else
 358                pos = 32;
 359                map_size = ex.a_text+ex.a_data;
 360#endif
 361                down_write(&current->mm->mmap_sem);
 362                error = do_brk(text_addr & PAGE_MASK, map_size);
 363                up_write(&current->mm->mmap_sem);
 364                if (error != (text_addr & PAGE_MASK)) {
 365                        send_sig(SIGKILL, current, 0);
 366                        return error;
 367                }
 368
 369                error = bprm->file->f_op->read(bprm->file,
 370                          (char __user *)text_addr,
 371                          ex.a_text+ex.a_data, &pos);
 372                if ((signed long)error < 0) {
 373                        send_sig(SIGKILL, current, 0);
 374                        return error;
 375                }
 376                         
 377                flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
 378        } else {
 379                static unsigned long error_time, error_time2;
 380                if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 381                    (N_MAGIC(ex) != NMAGIC) && (jiffies-error_time2) > 5*HZ)
 382                {
 383                        printk(KERN_NOTICE "executable not page aligned\n");
 384                        error_time2 = jiffies;
 385                }
 386
 387                if ((fd_offset & ~PAGE_MASK) != 0 &&
 388                    (jiffies-error_time) > 5*HZ)
 389                {
 390                        printk(KERN_WARNING 
 391                               "fd_offset is not page aligned. Please convert program: %s\n",
 392                               bprm->file->f_path.dentry->d_name.name);
 393                        error_time = jiffies;
 394                }
 395
 396                if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
 397                        loff_t pos = fd_offset;
 398                        down_write(&current->mm->mmap_sem);
 399                        do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 400                        up_write(&current->mm->mmap_sem);
 401                        bprm->file->f_op->read(bprm->file,
 402                                        (char __user *)N_TXTADDR(ex),
 403                                        ex.a_text+ex.a_data, &pos);
 404                        flush_icache_range((unsigned long) N_TXTADDR(ex),
 405                                           (unsigned long) N_TXTADDR(ex) +
 406                                           ex.a_text+ex.a_data);
 407                        goto beyond_if;
 408                }
 409
 410                down_write(&current->mm->mmap_sem);
 411                error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 412                        PROT_READ | PROT_EXEC,
 413                        MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 414                        fd_offset);
 415                up_write(&current->mm->mmap_sem);
 416
 417                if (error != N_TXTADDR(ex)) {
 418                        send_sig(SIGKILL, current, 0);
 419                        return error;
 420                }
 421
 422                down_write(&current->mm->mmap_sem);
 423                error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 424                                PROT_READ | PROT_WRITE | PROT_EXEC,
 425                                MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
 426                                fd_offset + ex.a_text);
 427                up_write(&current->mm->mmap_sem);
 428                if (error != N_DATADDR(ex)) {
 429                        send_sig(SIGKILL, current, 0);
 430                        return error;
 431                }
 432        }
 433beyond_if:
 434        set_binfmt(&aout_format);
 435
 436        retval = set_brk(current->mm->start_brk, current->mm->brk);
 437        if (retval < 0) {
 438                send_sig(SIGKILL, current, 0);
 439                return retval;
 440        }
 441
 442        retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
 443        if (retval < 0) { 
 444                /* Someone check-me: is this error path enough? */ 
 445                send_sig(SIGKILL, current, 0); 
 446                return retval;
 447        }
 448
 449        current->mm->start_stack =
 450                (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
 451#ifdef __alpha__
 452        regs->gp = ex.a_gpvalue;
 453#endif
 454        start_thread(regs, ex.a_entry, current->mm->start_stack);
 455        if (unlikely(current->ptrace & PT_PTRACED)) {
 456                if (current->ptrace & PT_TRACE_EXEC)
 457                        ptrace_notify ((PTRACE_EVENT_EXEC << 8) | SIGTRAP);
 458                else
 459                        send_sig(SIGTRAP, current, 0);
 460        }
 461        return 0;
 462}
 463
 464static int load_aout_library(struct file *file)
 465{
 466        struct inode * inode;
 467        unsigned long bss, start_addr, len;
 468        unsigned long error;
 469        int retval;
 470        struct exec ex;
 471
 472        inode = file->f_path.dentry->d_inode;
 473
 474        retval = -ENOEXEC;
 475        error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
 476        if (error != sizeof(ex))
 477                goto out;
 478
 479        /* We come in here for the regular a.out style of shared libraries */
 480        if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 481            N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 482            i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 483                goto out;
 484        }
 485
 486        /*
 487         * Requires a mmap handler. This prevents people from using a.out
 488         * as part of an exploit attack against /proc-related vulnerabilities.
 489         */
 490        if (!file->f_op || !file->f_op->mmap)
 491                goto out;
 492
 493        if (N_FLAGS(ex))
 494                goto out;
 495
 496        /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 497           this off to get the starting address for the page */
 498
 499        start_addr =  ex.a_entry & 0xfffff000;
 500
 501        if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 502                static unsigned long error_time;
 503                loff_t pos = N_TXTOFF(ex);
 504
 505                if ((jiffies-error_time) > 5*HZ)
 506                {
 507                        printk(KERN_WARNING 
 508                               "N_TXTOFF is not page aligned. Please convert library: %s\n",
 509                               file->f_path.dentry->d_name.name);
 510                        error_time = jiffies;
 511                }
 512                down_write(&current->mm->mmap_sem);
 513                do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 514                up_write(&current->mm->mmap_sem);
 515                
 516                file->f_op->read(file, (char __user *)start_addr,
 517                        ex.a_text + ex.a_data, &pos);
 518                flush_icache_range((unsigned long) start_addr,
 519                                   (unsigned long) start_addr + ex.a_text + ex.a_data);
 520
 521                retval = 0;
 522                goto out;
 523        }
 524        /* Now use mmap to map the library into memory. */
 525        down_write(&current->mm->mmap_sem);
 526        error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
 527                        PROT_READ | PROT_WRITE | PROT_EXEC,
 528                        MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
 529                        N_TXTOFF(ex));
 530        up_write(&current->mm->mmap_sem);
 531        retval = error;
 532        if (error != start_addr)
 533                goto out;
 534
 535        len = PAGE_ALIGN(ex.a_text + ex.a_data);
 536        bss = ex.a_text + ex.a_data + ex.a_bss;
 537        if (bss > len) {
 538                down_write(&current->mm->mmap_sem);
 539                error = do_brk(start_addr + len, bss - len);
 540                up_write(&current->mm->mmap_sem);
 541                retval = error;
 542                if (error != start_addr + len)
 543                        goto out;
 544        }
 545        retval = 0;
 546out:
 547        return retval;
 548}
 549
 550static int __init init_aout_binfmt(void)
 551{
 552        return register_binfmt(&aout_format);
 553}
 554
 555static void __exit exit_aout_binfmt(void)
 556{
 557        unregister_binfmt(&aout_format);
 558}
 559
 560core_initcall(init_aout_binfmt);
 561module_exit(exit_aout_binfmt);
 562MODULE_LICENSE("GPL");
 563