kernel/compat.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/kernel/compat.c
   4  *
   5  *  Kernel compatibililty routines for e.g. 32 bit syscall support
   6  *  on 64 bit kernels.
   7  *
   8  *  Copyright (C) 2002-2003 Stephen Rothwell, IBM Corporation
   9  */
  10
  11 #include <linux/linkage.h>
  12 #include <linux/compat.h>
  13 #include <linux/errno.h>
  14 #include <linux/time.h>
  15 #include <linux/signal.h>
  16 #include <linux/sched.h>        /* for MAX_SCHEDULE_TIMEOUT */
  17 #include <linux/syscalls.h>
  18 #include <linux/unistd.h>
  19 #include <linux/security.h>
  20 #include <linux/export.h>
  21 #include <linux/migrate.h>
  22 #include <linux/posix-timers.h>
  23 #include <linux/times.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/gfp.h>
  26
  27 #include <linux/uaccess.h>
  28
  29 static int __compat_get_timeval(struct timeval *tv, const struct old_timeval32 __user *ctv)
  30 {
  31         return (!access_ok(ctv, sizeof(*ctv)) ||
  32                         __get_user(tv->tv_sec, &ctv->tv_sec) ||
  33                         __get_user(tv->tv_usec, &ctv->tv_usec)) ? -EFAULT : 0;
  34 }
  35
  36 static int __compat_put_timeval(const struct timeval *tv, struct old_timeval32 __user *ctv)
  37 {
  38         return (!access_ok(ctv, sizeof(*ctv)) ||
  39                         __put_user(tv->tv_sec, &ctv->tv_sec) ||
  40                         __put_user(tv->tv_usec, &ctv->tv_usec)) ? -EFAULT : 0;
  41 }
  42
  43 static int __compat_get_timespec(struct timespec *ts, const struct old_timespec32 __user *cts)
  44 {
  45         return (!access_ok(cts, sizeof(*cts)) ||
  46                         __get_user(ts->tv_sec, &cts->tv_sec) ||
  47                         __get_user(ts->tv_nsec, &cts->tv_nsec)) ? -EFAULT : 0;
  48 }
  49
  50 static int __compat_put_timespec(const struct timespec *ts, struct old_timespec32 __user *cts)
  51 {
  52         return (!access_ok(cts, sizeof(*cts)) ||
  53                         __put_user(ts->tv_sec, &cts->tv_sec) ||
  54                         __put_user(ts->tv_nsec, &cts->tv_nsec)) ? -EFAULT : 0;
  55 }
  56
  57 int compat_get_timeval(struct timeval *tv, const void __user *utv)
  58 {
  59         if (COMPAT_USE_64BIT_TIME)
  60                 return copy_from_user(tv, utv, sizeof(*tv)) ? -EFAULT : 0;
  61         else
  62                 return __compat_get_timeval(tv, utv);
  63 }
  64 EXPORT_SYMBOL_GPL(compat_get_timeval);
  65
  66 int compat_put_timeval(const struct timeval *tv, void __user *utv)
  67 {
  68         if (COMPAT_USE_64BIT_TIME)
  69                 return copy_to_user(utv, tv, sizeof(*tv)) ? -EFAULT : 0;
  70         else
  71                 return __compat_put_timeval(tv, utv);
  72 }
  73 EXPORT_SYMBOL_GPL(compat_put_timeval);
  74
  75 int compat_get_timespec(struct timespec *ts, const void __user *uts)
  76 {
  77         if (COMPAT_USE_64BIT_TIME)
  78                 return copy_from_user(ts, uts, sizeof(*ts)) ? -EFAULT : 0;
  79         else
  80                 return __compat_get_timespec(ts, uts);
  81 }
  82 EXPORT_SYMBOL_GPL(compat_get_timespec);
  83
  84 int compat_put_timespec(const struct timespec *ts, void __user *uts)
  85 {
  86         if (COMPAT_USE_64BIT_TIME)
  87                 return copy_to_user(uts, ts, sizeof(*ts)) ? -EFAULT : 0;
  88         else
  89                 return __compat_put_timespec(ts, uts);
  90 }
  91 EXPORT_SYMBOL_GPL(compat_put_timespec);
  92
  93 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
  94
  95 /*
  96  * sys_sigprocmask SIG_SETMASK sets the first (compat) word of the
  97  * blocked set of signals to the supplied signal set
  98  */
  99 static inline void compat_sig_setmask(sigset_t *blocked, compat_sigset_word set)
 100 {
 101         memcpy(blocked->sig, &set, sizeof(set));
 102 }
 103
 104 COMPAT_SYSCALL_DEFINE3(sigprocmask, int, how,
 105                        compat_old_sigset_t __user *, nset,
 106                        compat_old_sigset_t __user *, oset)
 107 {
 108         old_sigset_t old_set, new_set;
 109         sigset_t new_blocked;
 110
 111         old_set = current->blocked.sig[0];
 112
 113         if (nset) {
 114                 if (get_user(new_set, nset))
 115                         return -EFAULT;
 116                 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
 117
 118                 new_blocked = current->blocked;
 119
 120                 switch (how) {
 121                 case SIG_BLOCK:
 122                         sigaddsetmask(&new_blocked, new_set);
 123                         break;
 124                 case SIG_UNBLOCK:
 125                         sigdelsetmask(&new_blocked, new_set);
 126                         break;
 127                 case SIG_SETMASK:
 128                         compat_sig_setmask(&new_blocked, new_set);
 129                         break;
 130                 default:
 131                         return -EINVAL;
 132                 }
 133
 134                 set_current_blocked(&new_blocked);
 135         }
 136
 137         if (oset) {
 138                 if (put_user(old_set, oset))
 139                         return -EFAULT;
 140         }
 141
 142         return 0;
 143 }
 144
 145 #endif
 146
 147 int put_compat_rusage(const struct rusage *r, struct compat_rusage __user *ru)
 148 {
 149         struct compat_rusage r32;
 150         memset(&r32, 0, sizeof(r32));
 151         r32.ru_utime.tv_sec = r->ru_utime.tv_sec;
 152         r32.ru_utime.tv_usec = r->ru_utime.tv_usec;
 153         r32.ru_stime.tv_sec = r->ru_stime.tv_sec;
 154         r32.ru_stime.tv_usec = r->ru_stime.tv_usec;
 155         r32.ru_maxrss = r->ru_maxrss;
 156         r32.ru_ixrss = r->ru_ixrss;
 157         r32.ru_idrss = r->ru_idrss;
 158         r32.ru_isrss = r->ru_isrss;
 159         r32.ru_minflt = r->ru_minflt;
 160         r32.ru_majflt = r->ru_majflt;
 161         r32.ru_nswap = r->ru_nswap;
 162         r32.ru_inblock = r->ru_inblock;
 163         r32.ru_oublock = r->ru_oublock;
 164         r32.ru_msgsnd = r->ru_msgsnd;
 165         r32.ru_msgrcv = r->ru_msgrcv;
 166         r32.ru_nsignals = r->ru_nsignals;
 167         r32.ru_nvcsw = r->ru_nvcsw;
 168         r32.ru_nivcsw = r->ru_nivcsw;
 169         if (copy_to_user(ru, &r32, sizeof(r32)))
 170                 return -EFAULT;
 171         return 0;
 172 }
 173
 174 static int compat_get_user_cpu_mask(compat_ulong_t __user *user_mask_ptr,
 175                                     unsigned len, struct cpumask *new_mask)
 176 {
 177         unsigned long *k;
 178
 179         if (len < cpumask_size())
 180                 memset(new_mask, 0, cpumask_size());
 181         else if (len > cpumask_size())
 182                 len = cpumask_size();
 183
 184         k = cpumask_bits(new_mask);
 185         return compat_get_bitmap(k, user_mask_ptr, len * 8);
 186 }
 187
 188 COMPAT_SYSCALL_DEFINE3(sched_setaffinity, compat_pid_t, pid,
 189                        unsigned int, len,
 190                        compat_ulong_t __user *, user_mask_ptr)
 191 {
 192         cpumask_var_t new_mask;
 193         int retval;
 194
 195         if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
 196                 return -ENOMEM;
 197
 198         retval = compat_get_user_cpu_mask(user_mask_ptr, len, new_mask);
 199         if (retval)
 200                 goto out;
 201
 202         retval = sched_setaffinity(pid, new_mask);
 203 out:
 204         free_cpumask_var(new_mask);
 205         return retval;
 206 }
 207
 208 COMPAT_SYSCALL_DEFINE3(sched_getaffinity, compat_pid_t,  pid, unsigned int, len,
 209                        compat_ulong_t __user *, user_mask_ptr)
 210 {
 211         int ret;
 212         cpumask_var_t mask;
 213
 214         if ((len * BITS_PER_BYTE) < nr_cpu_ids)
 215                 return -EINVAL;
 216         if (len & (sizeof(compat_ulong_t)-1))
 217                 return -EINVAL;
 218
 219         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 220                 return -ENOMEM;
 221
 222         ret = sched_getaffinity(pid, mask);
 223         if (ret == 0) {
 224                 unsigned int retlen = min(len, cpumask_size());
 225
 226                 if (compat_put_bitmap(user_mask_ptr, cpumask_bits(mask), retlen * 8))
 227                         ret = -EFAULT;
 228                 else
 229                         ret = retlen;
 230         }
 231         free_cpumask_var(mask);
 232
 233         return ret;
 234 }
 235
 236 /*
 237  * We currently only need the following fields from the sigevent
 238  * structure: sigev_value, sigev_signo, sig_notify and (sometimes
 239  * sigev_notify_thread_id).  The others are handled in user mode.
 240  * We also assume that copying sigev_value.sival_int is sufficient
 241  * to keep all the bits of sigev_value.sival_ptr intact.
 242  */
 243 int get_compat_sigevent(struct sigevent *event,
 244                 const struct compat_sigevent __user *u_event)
 245 {
 246         memset(event, 0, sizeof(*event));
 247         return (!access_ok(u_event, sizeof(*u_event)) ||
 248                 __get_user(event->sigev_value.sival_int,
 249                         &u_event->sigev_value.sival_int) ||
 250                 __get_user(event->sigev_signo, &u_event->sigev_signo) ||
 251                 __get_user(event->sigev_notify, &u_event->sigev_notify) ||
 252                 __get_user(event->sigev_notify_thread_id,
 253                         &u_event->sigev_notify_thread_id))
 254                 ? -EFAULT : 0;
 255 }
 256
 257 long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
 258                        unsigned long bitmap_size)
 259 {
 260         unsigned long nr_compat_longs;
 261
 262         /* align bitmap up to nearest compat_long_t boundary */
 263         bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
 264         nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
 265
 266         if (!user_access_begin(umask, bitmap_size / 8))
 267                 return -EFAULT;
 268
 269         while (nr_compat_longs > 1) {
 270                 compat_ulong_t l1, l2;
 271                 unsafe_get_user(l1, umask++, Efault);
 272                 unsafe_get_user(l2, umask++, Efault);
 273                 *mask++ = ((unsigned long)l2 << BITS_PER_COMPAT_LONG) | l1;
 274                 nr_compat_longs -= 2;
 275         }
 276         if (nr_compat_longs)
 277                 unsafe_get_user(*mask, umask++, Efault);
 278         user_access_end();
 279         return 0;
 280
 281 Efault:
 282         user_access_end();
 283         return -EFAULT;
 284 }
 285
 286 long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
 287                        unsigned long bitmap_size)
 288 {
 289         unsigned long nr_compat_longs;
 290
 291         /* align bitmap up to nearest compat_long_t boundary */
 292         bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
 293         nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
 294
 295         if (!user_access_begin(umask, bitmap_size / 8))
 296                 return -EFAULT;
 297
 298         while (nr_compat_longs > 1) {
 299                 unsigned long m = *mask++;
 300                 unsafe_put_user((compat_ulong_t)m, umask++, Efault);
 301                 unsafe_put_user(m >> BITS_PER_COMPAT_LONG, umask++, Efault);
 302                 nr_compat_longs -= 2;
 303         }
 304         if (nr_compat_longs)
 305                 unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
 306         user_access_end();
 307         return 0;
 308 Efault:
 309         user_access_end();
 310         return -EFAULT;
 311 }
 312
 313 int
 314 get_compat_sigset(sigset_t *set, const compat_sigset_t __user *compat)
 315 {
 316 #ifdef __BIG_ENDIAN
 317         compat_sigset_t v;
 318         if (copy_from_user(&v, compat, sizeof(compat_sigset_t)))
 319                 return -EFAULT;
 320         switch (_NSIG_WORDS) {
 321         case 4: set->sig[3] = v.sig[6] | (((long)v.sig[7]) << 32 );
 322                 /* fall through */
 323         case 3: set->sig[2] = v.sig[4] | (((long)v.sig[5]) << 32 );
 324                 /* fall through */
 325         case 2: set->sig[1] = v.sig[2] | (((long)v.sig[3]) << 32 );
 326                 /* fall through */
 327         case 1: set->sig[0] = v.sig[0] | (((long)v.sig[1]) << 32 );
 328         }
 329 #else
 330         if (copy_from_user(set, compat, sizeof(compat_sigset_t)))
 331                 return -EFAULT;
 332 #endif
 333         return 0;
 334 }
 335 EXPORT_SYMBOL_GPL(get_compat_sigset);
 336
 337 /*
 338  * Allocate user-space memory for the duration of a single system call,
 339  * in order to marshall parameters inside a compat thunk.
 340  */
 341 void __user *compat_alloc_user_space(unsigned long len)
 342 {
 343         void __user *ptr;
 344
 345         /* If len would occupy more than half of the entire compat space... */
 346         if (unlikely(len > (((compat_uptr_t)~0) >> 1)))
 347                 return NULL;
 348
 349         ptr = arch_compat_alloc_user_space(len);
 350
 351         if (unlikely(!access_ok(ptr, len)))
 352                 return NULL;
 353
 354         return ptr;
 355 }
 356 EXPORT_SYMBOL_GPL(compat_alloc_user_space);