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 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
  30
  31 /*
  32  * sys_sigprocmask SIG_SETMASK sets the first (compat) word of the
  33  * blocked set of signals to the supplied signal set
  34  */
  35 static inline void compat_sig_setmask(sigset_t *blocked, compat_sigset_word set)
  36 {
  37         memcpy(blocked->sig, &set, sizeof(set));
  38 }
  39
  40 COMPAT_SYSCALL_DEFINE3(sigprocmask, int, how,
  41                        compat_old_sigset_t __user *, nset,
  42                        compat_old_sigset_t __user *, oset)
  43 {
  44         old_sigset_t old_set, new_set;
  45         sigset_t new_blocked;
  46
  47         old_set = current->blocked.sig[0];
  48
  49         if (nset) {
  50                 if (get_user(new_set, nset))
  51                         return -EFAULT;
  52                 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
  53
  54                 new_blocked = current->blocked;
  55
  56                 switch (how) {
  57                 case SIG_BLOCK:
  58                         sigaddsetmask(&new_blocked, new_set);
  59                         break;
  60                 case SIG_UNBLOCK:
  61                         sigdelsetmask(&new_blocked, new_set);
  62                         break;
  63                 case SIG_SETMASK:
  64                         compat_sig_setmask(&new_blocked, new_set);
  65                         break;
  66                 default:
  67                         return -EINVAL;
  68                 }
  69
  70                 set_current_blocked(&new_blocked);
  71         }
  72
  73         if (oset) {
  74                 if (put_user(old_set, oset))
  75                         return -EFAULT;
  76         }
  77
  78         return 0;
  79 }
  80
  81 #endif
  82
  83 int put_compat_rusage(const struct rusage *r, struct compat_rusage __user *ru)
  84 {
  85         struct compat_rusage r32;
  86         memset(&r32, 0, sizeof(r32));
  87         r32.ru_utime.tv_sec = r->ru_utime.tv_sec;
  88         r32.ru_utime.tv_usec = r->ru_utime.tv_usec;
  89         r32.ru_stime.tv_sec = r->ru_stime.tv_sec;
  90         r32.ru_stime.tv_usec = r->ru_stime.tv_usec;
  91         r32.ru_maxrss = r->ru_maxrss;
  92         r32.ru_ixrss = r->ru_ixrss;
  93         r32.ru_idrss = r->ru_idrss;
  94         r32.ru_isrss = r->ru_isrss;
  95         r32.ru_minflt = r->ru_minflt;
  96         r32.ru_majflt = r->ru_majflt;
  97         r32.ru_nswap = r->ru_nswap;
  98         r32.ru_inblock = r->ru_inblock;
  99         r32.ru_oublock = r->ru_oublock;
 100         r32.ru_msgsnd = r->ru_msgsnd;
 101         r32.ru_msgrcv = r->ru_msgrcv;
 102         r32.ru_nsignals = r->ru_nsignals;
 103         r32.ru_nvcsw = r->ru_nvcsw;
 104         r32.ru_nivcsw = r->ru_nivcsw;
 105         if (copy_to_user(ru, &r32, sizeof(r32)))
 106                 return -EFAULT;
 107         return 0;
 108 }
 109
 110 static int compat_get_user_cpu_mask(compat_ulong_t __user *user_mask_ptr,
 111                                     unsigned len, struct cpumask *new_mask)
 112 {
 113         unsigned long *k;
 114
 115         if (len < cpumask_size())
 116                 memset(new_mask, 0, cpumask_size());
 117         else if (len > cpumask_size())
 118                 len = cpumask_size();
 119
 120         k = cpumask_bits(new_mask);
 121         return compat_get_bitmap(k, user_mask_ptr, len * 8);
 122 }
 123
 124 COMPAT_SYSCALL_DEFINE3(sched_setaffinity, compat_pid_t, pid,
 125                        unsigned int, len,
 126                        compat_ulong_t __user *, user_mask_ptr)
 127 {
 128         cpumask_var_t new_mask;
 129         int retval;
 130
 131         if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
 132                 return -ENOMEM;
 133
 134         retval = compat_get_user_cpu_mask(user_mask_ptr, len, new_mask);
 135         if (retval)
 136                 goto out;
 137
 138         retval = sched_setaffinity(pid, new_mask);
 139 out:
 140         free_cpumask_var(new_mask);
 141         return retval;
 142 }
 143
 144 COMPAT_SYSCALL_DEFINE3(sched_getaffinity, compat_pid_t,  pid, unsigned int, len,
 145                        compat_ulong_t __user *, user_mask_ptr)
 146 {
 147         int ret;
 148         cpumask_var_t mask;
 149
 150         if ((len * BITS_PER_BYTE) < nr_cpu_ids)
 151                 return -EINVAL;
 152         if (len & (sizeof(compat_ulong_t)-1))
 153                 return -EINVAL;
 154
 155         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 156                 return -ENOMEM;
 157
 158         ret = sched_getaffinity(pid, mask);
 159         if (ret == 0) {
 160                 unsigned int retlen = min(len, cpumask_size());
 161
 162                 if (compat_put_bitmap(user_mask_ptr, cpumask_bits(mask), retlen * 8))
 163                         ret = -EFAULT;
 164                 else
 165                         ret = retlen;
 166         }
 167         free_cpumask_var(mask);
 168
 169         return ret;
 170 }
 171
 172 /*
 173  * We currently only need the following fields from the sigevent
 174  * structure: sigev_value, sigev_signo, sig_notify and (sometimes
 175  * sigev_notify_thread_id).  The others are handled in user mode.
 176  * We also assume that copying sigev_value.sival_int is sufficient
 177  * to keep all the bits of sigev_value.sival_ptr intact.
 178  */
 179 int get_compat_sigevent(struct sigevent *event,
 180                 const struct compat_sigevent __user *u_event)
 181 {
 182         memset(event, 0, sizeof(*event));
 183         return (!access_ok(u_event, sizeof(*u_event)) ||
 184                 __get_user(event->sigev_value.sival_int,
 185                         &u_event->sigev_value.sival_int) ||
 186                 __get_user(event->sigev_signo, &u_event->sigev_signo) ||
 187                 __get_user(event->sigev_notify, &u_event->sigev_notify) ||
 188                 __get_user(event->sigev_notify_thread_id,
 189                         &u_event->sigev_notify_thread_id))
 190                 ? -EFAULT : 0;
 191 }
 192
 193 long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
 194                        unsigned long bitmap_size)
 195 {
 196         unsigned long nr_compat_longs;
 197
 198         /* align bitmap up to nearest compat_long_t boundary */
 199         bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
 200         nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
 201
 202         if (!user_read_access_begin(umask, bitmap_size / 8))
 203                 return -EFAULT;
 204
 205         while (nr_compat_longs > 1) {
 206                 compat_ulong_t l1, l2;
 207                 unsafe_get_user(l1, umask++, Efault);
 208                 unsafe_get_user(l2, umask++, Efault);
 209                 *mask++ = ((unsigned long)l2 << BITS_PER_COMPAT_LONG) | l1;
 210                 nr_compat_longs -= 2;
 211         }
 212         if (nr_compat_longs)
 213                 unsafe_get_user(*mask, umask++, Efault);
 214         user_read_access_end();
 215         return 0;
 216
 217 Efault:
 218         user_read_access_end();
 219         return -EFAULT;
 220 }
 221
 222 long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
 223                        unsigned long bitmap_size)
 224 {
 225         unsigned long nr_compat_longs;
 226
 227         /* align bitmap up to nearest compat_long_t boundary */
 228         bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
 229         nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
 230
 231         if (!user_write_access_begin(umask, bitmap_size / 8))
 232                 return -EFAULT;
 233
 234         while (nr_compat_longs > 1) {
 235                 unsigned long m = *mask++;
 236                 unsafe_put_user((compat_ulong_t)m, umask++, Efault);
 237                 unsafe_put_user(m >> BITS_PER_COMPAT_LONG, umask++, Efault);
 238                 nr_compat_longs -= 2;
 239         }
 240         if (nr_compat_longs)
 241                 unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
 242         user_write_access_end();
 243         return 0;
 244 Efault:
 245         user_write_access_end();
 246         return -EFAULT;
 247 }
 248
 249 int
 250 get_compat_sigset(sigset_t *set, const compat_sigset_t __user *compat)
 251 {
 252 #ifdef __BIG_ENDIAN
 253         compat_sigset_t v;
 254         if (copy_from_user(&v, compat, sizeof(compat_sigset_t)))
 255                 return -EFAULT;
 256         switch (_NSIG_WORDS) {
 257         case 4: set->sig[3] = v.sig[6] | (((long)v.sig[7]) << 32 );
 258                 fallthrough;
 259         case 3: set->sig[2] = v.sig[4] | (((long)v.sig[5]) << 32 );
 260                 fallthrough;
 261         case 2: set->sig[1] = v.sig[2] | (((long)v.sig[3]) << 32 );
 262                 fallthrough;
 263         case 1: set->sig[0] = v.sig[0] | (((long)v.sig[1]) << 32 );
 264         }
 265 #else
 266         if (copy_from_user(set, compat, sizeof(compat_sigset_t)))
 267                 return -EFAULT;
 268 #endif
 269         return 0;
 270 }
 271 EXPORT_SYMBOL_GPL(get_compat_sigset);
 272
 273 /*
 274  * Allocate user-space memory for the duration of a single system call,
 275  * in order to marshall parameters inside a compat thunk.
 276  */
 277 void __user *compat_alloc_user_space(unsigned long len)
 278 {
 279         void __user *ptr;
 280
 281         /* If len would occupy more than half of the entire compat space... */
 282         if (unlikely(len > (((compat_uptr_t)~0) >> 1)))
 283                 return NULL;
 284
 285         ptr = arch_compat_alloc_user_space(len);
 286
 287         if (unlikely(!access_ok(ptr, len)))
 288                 return NULL;
 289
 290         return ptr;
 291 }
 292 EXPORT_SYMBOL_GPL(compat_alloc_user_space);