kernel/compat.c

   1 /*
   2  *  linux/kernel/compat.c
   3  *
   4  *  Kernel compatibililty routines for e.g. 32 bit syscall support
   5  *  on 64 bit kernels.
   6  *
   7  *  Copyright (C) 2002-2003 Stephen Rothwell, IBM Corporation
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2 as
  11  *  published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/linkage.h>
  15 #include <linux/compat.h>
  16 #include <linux/errno.h>
  17 #include <linux/time.h>
  18 #include <linux/signal.h>
  19 #include <linux/sched.h>        /* for MAX_SCHEDULE_TIMEOUT */
  20 #include <linux/futex.h>        /* for FUTEX_WAIT */
  21 #include <linux/syscalls.h>
  22 #include <linux/unistd.h>
  23
  24 #include <asm/uaccess.h>
  25
  26 int get_compat_timespec(struct timespec *ts, const struct compat_timespec __user *cts)
  27 {
  28         return (verify_area(VERIFY_READ, cts, sizeof(*cts)) ||
  29                         __get_user(ts->tv_sec, &cts->tv_sec) ||
  30                         __get_user(ts->tv_nsec, &cts->tv_nsec)) ? -EFAULT : 0;
  31 }
  32
  33 int put_compat_timespec(const struct timespec *ts, struct compat_timespec __user *cts)
  34 {
  35         return (verify_area(VERIFY_WRITE, cts, sizeof(*cts)) ||
  36                         __put_user(ts->tv_sec, &cts->tv_sec) ||
  37                         __put_user(ts->tv_nsec, &cts->tv_nsec)) ? -EFAULT : 0;
  38 }
  39
  40 static long compat_nanosleep_restart(struct restart_block *restart)
  41 {
  42         unsigned long expire = restart->arg0, now = jiffies;
  43         struct compat_timespec __user *rmtp;
  44
  45         /* Did it expire while we handled signals? */
  46         if (!time_after(expire, now))
  47                 return 0;
  48
  49         current->state = TASK_INTERRUPTIBLE;
  50         expire = schedule_timeout(expire - now);
  51         if (expire == 0)
  52                 return 0;
  53
  54         rmtp = (struct compat_timespec __user *)restart->arg1;
  55         if (rmtp) {
  56                 struct compat_timespec ct;
  57                 struct timespec t;
  58
  59                 jiffies_to_timespec(expire, &t);
  60                 ct.tv_sec = t.tv_sec;
  61                 ct.tv_nsec = t.tv_nsec;
  62                 if (copy_to_user(rmtp, &ct, sizeof(ct)))
  63                         return -EFAULT;
  64         }
  65         /* The 'restart' block is already filled in */
  66         return -ERESTART_RESTARTBLOCK;
  67 }
  68
  69 asmlinkage long compat_sys_nanosleep(struct compat_timespec __user *rqtp,
  70                 struct compat_timespec __user *rmtp)
  71 {
  72         struct timespec t;
  73         struct restart_block *restart;
  74         unsigned long expire;
  75
  76         if (get_compat_timespec(&t, rqtp))
  77                 return -EFAULT;
  78
  79         if ((t.tv_nsec >= 1000000000L) || (t.tv_nsec < 0) || (t.tv_sec < 0))
  80                 return -EINVAL;
  81
  82         expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec);
  83         current->state = TASK_INTERRUPTIBLE;
  84         expire = schedule_timeout(expire);
  85         if (expire == 0)
  86                 return 0;
  87
  88         if (rmtp) {
  89                 jiffies_to_timespec(expire, &t);
  90                 if (put_compat_timespec(&t, rmtp))
  91                         return -EFAULT;
  92         }
  93         restart = &current_thread_info()->restart_block;
  94         restart->fn = compat_nanosleep_restart;
  95         restart->arg0 = jiffies + expire;
  96         restart->arg1 = (unsigned long) rmtp;
  97         return -ERESTART_RESTARTBLOCK;
  98 }
  99
 100 static inline long get_compat_itimerval(struct itimerval *o,
 101                 struct compat_itimerval __user *i)
 102 {
 103         return (!access_ok(VERIFY_READ, i, sizeof(*i)) ||
 104                 (__get_user(o->it_interval.tv_sec, &i->it_interval.tv_sec) |
 105                  __get_user(o->it_interval.tv_usec, &i->it_interval.tv_usec) |
 106                  __get_user(o->it_value.tv_sec, &i->it_value.tv_sec) |
 107                  __get_user(o->it_value.tv_usec, &i->it_value.tv_usec)));
 108 }
 109
 110 static inline long put_compat_itimerval(struct compat_itimerval __user *o,
 111                 struct itimerval *i)
 112 {
 113         return (!access_ok(VERIFY_WRITE, o, sizeof(*o)) ||
 114                 (__put_user(i->it_interval.tv_sec, &o->it_interval.tv_sec) |
 115                  __put_user(i->it_interval.tv_usec, &o->it_interval.tv_usec) |
 116                  __put_user(i->it_value.tv_sec, &o->it_value.tv_sec) |
 117                  __put_user(i->it_value.tv_usec, &o->it_value.tv_usec)));
 118 }
 119
 120 asmlinkage long compat_sys_getitimer(int which,
 121                 struct compat_itimerval __user *it)
 122 {
 123         struct itimerval kit;
 124         int error;
 125
 126         error = do_getitimer(which, &kit);
 127         if (!error && put_compat_itimerval(it, &kit))
 128                 error = -EFAULT;
 129         return error;
 130 }
 131
 132 asmlinkage long compat_sys_setitimer(int which,
 133                 struct compat_itimerval __user *in,
 134                 struct compat_itimerval __user *out)
 135 {
 136         struct itimerval kin, kout;
 137         int error;
 138
 139         if (in) {
 140                 if (get_compat_itimerval(&kin, in))
 141                         return -EFAULT;
 142         } else
 143                 memset(&kin, 0, sizeof(kin));
 144
 145         error = do_setitimer(which, &kin, out ? &kout : NULL);
 146         if (error || !out)
 147                 return error;
 148         if (put_compat_itimerval(out, &kout))
 149                 return -EFAULT;
 150         return 0;
 151 }
 152
 153 asmlinkage long compat_sys_times(struct compat_tms __user *tbuf)
 154 {
 155         /*
 156          *      In the SMP world we might just be unlucky and have one of
 157          *      the times increment as we use it. Since the value is an
 158          *      atomically safe type this is just fine. Conceptually its
 159          *      as if the syscall took an instant longer to occur.
 160          */
 161         if (tbuf) {
 162                 struct compat_tms tmp;
 163                 struct task_struct *tsk = current;
 164                 struct task_struct *t;
 165                 unsigned long utime, stime, cutime, cstime;
 166
 167                 read_lock(&tasklist_lock);
 168                 utime = tsk->signal->utime;
 169                 stime = tsk->signal->stime;
 170                 t = tsk;
 171                 do {
 172                         utime += t->utime;
 173                         stime += t->stime;
 174                         t = next_thread(t);
 175                 } while (t != tsk);
 176
 177                 /*
 178                  * While we have tasklist_lock read-locked, no dying thread
 179                  * can be updating current->signal->[us]time.  Instead,
 180                  * we got their counts included in the live thread loop.
 181                  * However, another thread can come in right now and
 182                  * do a wait call that updates current->signal->c[us]time.
 183                  * To make sure we always see that pair updated atomically,
 184                  * we take the siglock around fetching them.
 185                  */
 186                 spin_lock_irq(&tsk->sighand->siglock);
 187                 cutime = tsk->signal->cutime;
 188                 cstime = tsk->signal->cstime;
 189                 spin_unlock_irq(&tsk->sighand->siglock);
 190                 read_unlock(&tasklist_lock);
 191
 192                 tmp.tms_utime = compat_jiffies_to_clock_t(utime);
 193                 tmp.tms_stime = compat_jiffies_to_clock_t(stime);
 194                 tmp.tms_cutime = compat_jiffies_to_clock_t(cutime);
 195                 tmp.tms_cstime = compat_jiffies_to_clock_t(cstime);
 196                 if (copy_to_user(tbuf, &tmp, sizeof(tmp)))
 197                         return -EFAULT;
 198         }
 199         return compat_jiffies_to_clock_t(jiffies);
 200 }
 201
 202 /*
 203  * Assumption: old_sigset_t and compat_old_sigset_t are both
 204  * types that can be passed to put_user()/get_user().
 205  */
 206
 207 asmlinkage long compat_sys_sigpending(compat_old_sigset_t __user *set)
 208 {
 209         old_sigset_t s;
 210         long ret;
 211         mm_segment_t old_fs = get_fs();
 212
 213         set_fs(KERNEL_DS);
 214         ret = sys_sigpending((old_sigset_t __user *) &s);
 215         set_fs(old_fs);
 216         if (ret == 0)
 217                 ret = put_user(s, set);
 218         return ret;
 219 }
 220
 221 asmlinkage long compat_sys_sigprocmask(int how, compat_old_sigset_t __user *set,
 222                 compat_old_sigset_t __user *oset)
 223 {
 224         old_sigset_t s;
 225         long ret;
 226         mm_segment_t old_fs;
 227
 228         if (set && get_user(s, set))
 229                 return -EFAULT;
 230         old_fs = get_fs();
 231         set_fs(KERNEL_DS);
 232         ret = sys_sigprocmask(how,
 233                               set ? (old_sigset_t __user *) &s : NULL,
 234                               oset ? (old_sigset_t __user *) &s : NULL);
 235         set_fs(old_fs);
 236         if (ret == 0)
 237                 if (oset)
 238                         ret = put_user(s, oset);
 239         return ret;
 240 }
 241
 242 #ifdef CONFIG_FUTEX
 243 asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, int val,
 244                 struct compat_timespec __user *utime, u32 __user *uaddr2,
 245                 int val3)
 246 {
 247         struct timespec t;
 248         unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
 249         int val2 = 0;
 250
 251         if ((op == FUTEX_WAIT) && utime) {
 252                 if (get_compat_timespec(&t, utime))
 253                         return -EFAULT;
 254                 timeout = timespec_to_jiffies(&t) + 1;
 255         }
 256         if (op >= FUTEX_REQUEUE)
 257                 val2 = (int) (unsigned long) utime;
 258
 259         return do_futex((unsigned long)uaddr, op, val, timeout,
 260                         (unsigned long)uaddr2, val2, val3);
 261 }
 262 #endif
 263
 264 asmlinkage long compat_sys_setrlimit(unsigned int resource,
 265                 struct compat_rlimit __user *rlim)
 266 {
 267         struct rlimit r;
 268         int ret;
 269         mm_segment_t old_fs = get_fs ();
 270
 271         if (resource >= RLIM_NLIMITS)
 272                 return -EINVAL;
 273
 274         if (!access_ok(VERIFY_READ, rlim, sizeof(*rlim)) ||
 275             __get_user(r.rlim_cur, &rlim->rlim_cur) ||
 276             __get_user(r.rlim_max, &rlim->rlim_max))
 277                 return -EFAULT;
 278
 279         if (r.rlim_cur == COMPAT_RLIM_INFINITY)
 280                 r.rlim_cur = RLIM_INFINITY;
 281         if (r.rlim_max == COMPAT_RLIM_INFINITY)
 282                 r.rlim_max = RLIM_INFINITY;
 283         set_fs(KERNEL_DS);
 284         ret = sys_setrlimit(resource, (struct rlimit __user *) &r);
 285         set_fs(old_fs);
 286         return ret;
 287 }
 288
 289 #ifdef COMPAT_RLIM_OLD_INFINITY
 290
 291 asmlinkage long compat_sys_old_getrlimit(unsigned int resource,
 292                 struct compat_rlimit __user *rlim)
 293 {
 294         struct rlimit r;
 295         int ret;
 296         mm_segment_t old_fs = get_fs();
 297
 298         set_fs(KERNEL_DS);
 299         ret = sys_old_getrlimit(resource, &r);
 300         set_fs(old_fs);
 301
 302         if (!ret) {
 303                 if (r.rlim_cur > COMPAT_RLIM_OLD_INFINITY)
 304                         r.rlim_cur = COMPAT_RLIM_INFINITY;
 305                 if (r.rlim_max > COMPAT_RLIM_OLD_INFINITY)
 306                         r.rlim_max = COMPAT_RLIM_INFINITY;
 307
 308                 if (!access_ok(VERIFY_WRITE, rlim, sizeof(*rlim)) ||
 309                     __put_user(r.rlim_cur, &rlim->rlim_cur) ||
 310                     __put_user(r.rlim_max, &rlim->rlim_max))
 311                         return -EFAULT;
 312         }
 313         return ret;
 314 }
 315
 316 #endif
 317
 318 asmlinkage long compat_sys_getrlimit (unsigned int resource,
 319                 struct compat_rlimit __user *rlim)
 320 {
 321         struct rlimit r;
 322         int ret;
 323         mm_segment_t old_fs = get_fs();
 324
 325         set_fs(KERNEL_DS);
 326         ret = sys_getrlimit(resource, (struct rlimit __user *) &r);
 327         set_fs(old_fs);
 328         if (!ret) {
 329                 if (r.rlim_cur > COMPAT_RLIM_INFINITY)
 330                         r.rlim_cur = COMPAT_RLIM_INFINITY;
 331                 if (r.rlim_max > COMPAT_RLIM_INFINITY)
 332                         r.rlim_max = COMPAT_RLIM_INFINITY;
 333
 334                 if (!access_ok(VERIFY_WRITE, rlim, sizeof(*rlim)) ||
 335                     __put_user(r.rlim_cur, &rlim->rlim_cur) ||
 336                     __put_user(r.rlim_max, &rlim->rlim_max))
 337                         return -EFAULT;
 338         }
 339         return ret;
 340 }
 341
 342 int put_compat_rusage(const struct rusage *r, struct compat_rusage __user *ru)
 343 {
 344         if (!access_ok(VERIFY_WRITE, ru, sizeof(*ru)) ||
 345             __put_user(r->ru_utime.tv_sec, &ru->ru_utime.tv_sec) ||
 346             __put_user(r->ru_utime.tv_usec, &ru->ru_utime.tv_usec) ||
 347             __put_user(r->ru_stime.tv_sec, &ru->ru_stime.tv_sec) ||
 348             __put_user(r->ru_stime.tv_usec, &ru->ru_stime.tv_usec) ||
 349             __put_user(r->ru_maxrss, &ru->ru_maxrss) ||
 350             __put_user(r->ru_ixrss, &ru->ru_ixrss) ||
 351             __put_user(r->ru_idrss, &ru->ru_idrss) ||
 352             __put_user(r->ru_isrss, &ru->ru_isrss) ||
 353             __put_user(r->ru_minflt, &ru->ru_minflt) ||
 354             __put_user(r->ru_majflt, &ru->ru_majflt) ||
 355             __put_user(r->ru_nswap, &ru->ru_nswap) ||
 356             __put_user(r->ru_inblock, &ru->ru_inblock) ||
 357             __put_user(r->ru_oublock, &ru->ru_oublock) ||
 358             __put_user(r->ru_msgsnd, &ru->ru_msgsnd) ||
 359             __put_user(r->ru_msgrcv, &ru->ru_msgrcv) ||
 360             __put_user(r->ru_nsignals, &ru->ru_nsignals) ||
 361             __put_user(r->ru_nvcsw, &ru->ru_nvcsw) ||
 362             __put_user(r->ru_nivcsw, &ru->ru_nivcsw))
 363                 return -EFAULT;
 364         return 0;
 365 }
 366
 367 asmlinkage long compat_sys_getrusage(int who, struct compat_rusage __user *ru)
 368 {
 369         struct rusage r;
 370         int ret;
 371         mm_segment_t old_fs = get_fs();
 372
 373         set_fs(KERNEL_DS);
 374         ret = sys_getrusage(who, (struct rusage __user *) &r);
 375         set_fs(old_fs);
 376
 377         if (ret)
 378                 return ret;
 379
 380         if (put_compat_rusage(&r, ru))
 381                 return -EFAULT;
 382
 383         return 0;
 384 }
 385
 386 asmlinkage long
 387 compat_sys_wait4(compat_pid_t pid, compat_uint_t __user *stat_addr, int options,
 388         struct compat_rusage __user *ru)
 389 {
 390         if (!ru) {
 391                 return sys_wait4(pid, stat_addr, options, NULL);
 392         } else {
 393                 struct rusage r;
 394                 int ret;
 395                 unsigned int status;
 396                 mm_segment_t old_fs = get_fs();
 397
 398                 set_fs (KERNEL_DS);
 399                 ret = sys_wait4(pid,
 400                                 (stat_addr ?
 401                                  (unsigned int __user *) &status : NULL),
 402                                 options, (struct rusage __user *) &r);
 403                 set_fs (old_fs);
 404
 405                 if (ret > 0) {
 406                         if (put_compat_rusage(&r, ru))
 407                                 return -EFAULT;
 408                         if (stat_addr && put_user(status, stat_addr))
 409                                 return -EFAULT;
 410                 }
 411                 return ret;
 412         }
 413 }
 414
 415 static int compat_get_user_cpu_mask(compat_ulong_t __user *user_mask_ptr,
 416                                     unsigned len, cpumask_t *new_mask)
 417 {
 418         unsigned long *k;
 419
 420         if (len < sizeof(cpumask_t))
 421                 memset(new_mask, 0, sizeof(cpumask_t));
 422         else if (len > sizeof(cpumask_t))
 423                 len = sizeof(cpumask_t);
 424
 425         k = cpus_addr(*new_mask);
 426         return compat_get_bitmap(k, user_mask_ptr, len * 8);
 427 }
 428
 429 asmlinkage long compat_sys_sched_setaffinity(compat_pid_t pid,
 430                                              unsigned int len,
 431                                              compat_ulong_t __user *user_mask_ptr)
 432 {
 433         cpumask_t new_mask;
 434         int retval;
 435
 436         retval = compat_get_user_cpu_mask(user_mask_ptr, len, &new_mask);
 437         if (retval)
 438                 return retval;
 439
 440         return sched_setaffinity(pid, new_mask);
 441 }
 442
 443 asmlinkage long compat_sys_sched_getaffinity(compat_pid_t pid, unsigned int len,
 444                                              compat_ulong_t __user *user_mask_ptr)
 445 {
 446         int ret;
 447         cpumask_t mask;
 448         unsigned long *k;
 449         unsigned int min_length = sizeof(cpumask_t);
 450
 451         if (NR_CPUS <= BITS_PER_COMPAT_LONG)
 452                 min_length = sizeof(compat_ulong_t);
 453
 454         if (len < min_length)
 455                 return -EINVAL;
 456
 457         ret = sched_getaffinity(pid, &mask);
 458         if (ret < 0)
 459                 return ret;
 460
 461         k = cpus_addr(mask);
 462         ret = compat_put_bitmap(user_mask_ptr, k, min_length * 8);
 463         if (ret)
 464                 return ret;
 465
 466         return min_length;
 467 }
 468
 469 static int get_compat_itimerspec(struct itimerspec *dst,
 470                                  struct compat_itimerspec __user *src)
 471 {
 472         if (get_compat_timespec(&dst->it_interval, &src->it_interval) ||
 473             get_compat_timespec(&dst->it_value, &src->it_value))
 474                 return -EFAULT;
 475         return 0;
 476 }
 477
 478 static int put_compat_itimerspec(struct compat_itimerspec __user *dst,
 479                                  struct itimerspec *src)
 480 {
 481         if (put_compat_timespec(&src->it_interval, &dst->it_interval) ||
 482             put_compat_timespec(&src->it_value, &dst->it_value))
 483                 return -EFAULT;
 484         return 0;
 485 }
 486
 487 long compat_timer_settime(timer_t timer_id, int flags,
 488                           struct compat_itimerspec __user *new,
 489                           struct compat_itimerspec __user *old)
 490 {
 491         long err;
 492         mm_segment_t oldfs;
 493         struct itimerspec newts, oldts;
 494
 495         if (!new)
 496                 return -EINVAL;
 497         if (get_compat_itimerspec(&newts, new))
 498                 return -EFAULT;
 499         oldfs = get_fs();
 500         set_fs(KERNEL_DS);
 501         err = sys_timer_settime(timer_id, flags,
 502                                 (struct itimerspec __user *) &newts,
 503                                 (struct itimerspec __user *) &oldts);
 504         set_fs(oldfs);
 505         if (!err && old && put_compat_itimerspec(old, &oldts))
 506                 return -EFAULT;
 507         return err;
 508 }
 509
 510 long compat_timer_gettime(timer_t timer_id,
 511                 struct compat_itimerspec __user *setting)
 512 {
 513         long err;
 514         mm_segment_t oldfs;
 515         struct itimerspec ts;
 516
 517         oldfs = get_fs();
 518         set_fs(KERNEL_DS);
 519         err = sys_timer_gettime(timer_id,
 520                                 (struct itimerspec __user *) &ts);
 521         set_fs(oldfs);
 522         if (!err && put_compat_itimerspec(setting, &ts))
 523                 return -EFAULT;
 524         return err;
 525 }
 526
 527 long compat_clock_settime(clockid_t which_clock,
 528                 struct compat_timespec __user *tp)
 529 {
 530         long err;
 531         mm_segment_t oldfs;
 532         struct timespec ts;
 533
 534         if (get_compat_timespec(&ts, tp))
 535                 return -EFAULT;
 536         oldfs = get_fs();
 537         set_fs(KERNEL_DS);
 538         err = sys_clock_settime(which_clock,
 539                                 (struct timespec __user *) &ts);
 540         set_fs(oldfs);
 541         return err;
 542 }
 543
 544 long compat_clock_gettime(clockid_t which_clock,
 545                 struct compat_timespec __user *tp)
 546 {
 547         long err;
 548         mm_segment_t oldfs;
 549         struct timespec ts;
 550
 551         oldfs = get_fs();
 552         set_fs(KERNEL_DS);
 553         err = sys_clock_gettime(which_clock,
 554                                 (struct timespec __user *) &ts);
 555         set_fs(oldfs);
 556         if (!err && put_compat_timespec(&ts, tp))
 557                 return -EFAULT;
 558         return err;
 559 }
 560
 561 long compat_clock_getres(clockid_t which_clock,
 562                 struct compat_timespec __user *tp)
 563 {
 564         long err;
 565         mm_segment_t oldfs;
 566         struct timespec ts;
 567
 568         oldfs = get_fs();
 569         set_fs(KERNEL_DS);
 570         err = sys_clock_getres(which_clock,
 571                                (struct timespec __user *) &ts);
 572         set_fs(oldfs);
 573         if (!err && tp && put_compat_timespec(&ts, tp))
 574                 return -EFAULT;
 575         return err;
 576 }
 577
 578 long compat_clock_nanosleep(clockid_t which_clock, int flags,
 579                             struct compat_timespec __user *rqtp,
 580                             struct compat_timespec __user *rmtp)
 581 {
 582         long err;
 583         mm_segment_t oldfs;
 584         struct timespec in, out;
 585
 586         if (get_compat_timespec(&in, rqtp))
 587                 return -EFAULT;
 588
 589         oldfs = get_fs();
 590         set_fs(KERNEL_DS);
 591         err = sys_clock_nanosleep(which_clock, flags,
 592                                   (struct timespec __user *) &in,
 593                                   (struct timespec __user *) &out);
 594         set_fs(oldfs);
 595         if ((err == -ERESTART_RESTARTBLOCK) && rmtp &&
 596             put_compat_timespec(&out, rmtp))
 597                 return -EFAULT;
 598         return err;
 599 }
 600
 601 /* timer_create is architecture specific because it needs sigevent conversion */
 602
 603 long compat_get_bitmap(unsigned long *mask, compat_ulong_t __user *umask,
 604                        unsigned long bitmap_size)
 605 {
 606         int i, j;
 607         unsigned long m;
 608         compat_ulong_t um;
 609         unsigned long nr_compat_longs;
 610
 611         /* align bitmap up to nearest compat_long_t boundary */
 612         bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
 613
 614         if (verify_area(VERIFY_READ, umask, bitmap_size / 8))
 615                 return -EFAULT;
 616
 617         nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
 618
 619         for (i = 0; i < BITS_TO_LONGS(bitmap_size); i++) {
 620                 m = 0;
 621
 622                 for (j = 0; j < sizeof(m)/sizeof(um); j++) {
 623                         /*
 624                          * We dont want to read past the end of the userspace
 625                          * bitmap. We must however ensure the end of the
 626                          * kernel bitmap is zeroed.
 627                          */
 628                         if (nr_compat_longs-- > 0) {
 629                                 if (__get_user(um, umask))
 630                                         return -EFAULT;
 631                         } else {
 632                                 um = 0;
 633                         }
 634
 635                         umask++;
 636                         m |= (long)um << (j * BITS_PER_COMPAT_LONG);
 637                 }
 638                 *mask++ = m;
 639         }
 640
 641         return 0;
 642 }
 643
 644 long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
 645                        unsigned long bitmap_size)
 646 {
 647         int i, j;
 648         unsigned long m;
 649         compat_ulong_t um;
 650         unsigned long nr_compat_longs;
 651
 652         /* align bitmap up to nearest compat_long_t boundary */
 653         bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
 654
 655         if (verify_area(VERIFY_WRITE, umask, bitmap_size / 8))
 656                 return -EFAULT;
 657
 658         nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
 659
 660         for (i = 0; i < BITS_TO_LONGS(bitmap_size); i++) {
 661                 m = *mask++;
 662
 663                 for (j = 0; j < sizeof(m)/sizeof(um); j++) {
 664                         um = m;
 665
 666                         /*
 667                          * We dont want to write past the end of the userspace
 668                          * bitmap.
 669                          */
 670                         if (nr_compat_longs-- > 0) {
 671                                 if (__put_user(um, umask))
 672                                         return -EFAULT;
 673                         }
 674
 675                         umask++;
 676                         m >>= 4*sizeof(um);
 677                         m >>= 4*sizeof(um);
 678                 }
 679         }
 680
 681         return 0;
 682 }