xref: /linux/kernel/compat.c (revision 44f57d78) 
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 int get_compat_itimerval(struct itimerval *o, const struct compat_itimerval __user *i)
94 {
95 	struct compat_itimerval v32;
96 
97 	if (copy_from_user(&v32, i, sizeof(struct compat_itimerval)))
98 		return -EFAULT;
99 	o->it_interval.tv_sec = v32.it_interval.tv_sec;
100 	o->it_interval.tv_usec = v32.it_interval.tv_usec;
101 	o->it_value.tv_sec = v32.it_value.tv_sec;
102 	o->it_value.tv_usec = v32.it_value.tv_usec;
103 	return 0;
104 }
105 
106 int put_compat_itimerval(struct compat_itimerval __user *o, const struct itimerval *i)
107 {
108 	struct compat_itimerval v32;
109 
110 	v32.it_interval.tv_sec = i->it_interval.tv_sec;
111 	v32.it_interval.tv_usec = i->it_interval.tv_usec;
112 	v32.it_value.tv_sec = i->it_value.tv_sec;
113 	v32.it_value.tv_usec = i->it_value.tv_usec;
114 	return copy_to_user(o, &v32, sizeof(struct compat_itimerval)) ? -EFAULT : 0;
115 }
116 
117 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
118 
119 /*
120  * sys_sigprocmask SIG_SETMASK sets the first (compat) word of the
121  * blocked set of signals to the supplied signal set
122  */
123 static inline void compat_sig_setmask(sigset_t *blocked, compat_sigset_word set)
124 {
125 	memcpy(blocked->sig, &set, sizeof(set));
126 }
127 
128 COMPAT_SYSCALL_DEFINE3(sigprocmask, int, how,
129 		       compat_old_sigset_t __user *, nset,
130 		       compat_old_sigset_t __user *, oset)
131 {
132 	old_sigset_t old_set, new_set;
133 	sigset_t new_blocked;
134 
135 	old_set = current->blocked.sig[0];
136 
137 	if (nset) {
138 		if (get_user(new_set, nset))
139 			return -EFAULT;
140 		new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
141 
142 		new_blocked = current->blocked;
143 
144 		switch (how) {
145 		case SIG_BLOCK:
146 			sigaddsetmask(&new_blocked, new_set);
147 			break;
148 		case SIG_UNBLOCK:
149 			sigdelsetmask(&new_blocked, new_set);
150 			break;
151 		case SIG_SETMASK:
152 			compat_sig_setmask(&new_blocked, new_set);
153 			break;
154 		default:
155 			return -EINVAL;
156 		}
157 
158 		set_current_blocked(&new_blocked);
159 	}
160 
161 	if (oset) {
162 		if (put_user(old_set, oset))
163 			return -EFAULT;
164 	}
165 
166 	return 0;
167 }
168 
169 #endif
170 
171 int put_compat_rusage(const struct rusage *r, struct compat_rusage __user *ru)
172 {
173 	struct compat_rusage r32;
174 	memset(&r32, 0, sizeof(r32));
175 	r32.ru_utime.tv_sec = r->ru_utime.tv_sec;
176 	r32.ru_utime.tv_usec = r->ru_utime.tv_usec;
177 	r32.ru_stime.tv_sec = r->ru_stime.tv_sec;
178 	r32.ru_stime.tv_usec = r->ru_stime.tv_usec;
179 	r32.ru_maxrss = r->ru_maxrss;
180 	r32.ru_ixrss = r->ru_ixrss;
181 	r32.ru_idrss = r->ru_idrss;
182 	r32.ru_isrss = r->ru_isrss;
183 	r32.ru_minflt = r->ru_minflt;
184 	r32.ru_majflt = r->ru_majflt;
185 	r32.ru_nswap = r->ru_nswap;
186 	r32.ru_inblock = r->ru_inblock;
187 	r32.ru_oublock = r->ru_oublock;
188 	r32.ru_msgsnd = r->ru_msgsnd;
189 	r32.ru_msgrcv = r->ru_msgrcv;
190 	r32.ru_nsignals = r->ru_nsignals;
191 	r32.ru_nvcsw = r->ru_nvcsw;
192 	r32.ru_nivcsw = r->ru_nivcsw;
193 	if (copy_to_user(ru, &r32, sizeof(r32)))
194 		return -EFAULT;
195 	return 0;
196 }
197 
198 static int compat_get_user_cpu_mask(compat_ulong_t __user *user_mask_ptr,
199 				    unsigned len, struct cpumask *new_mask)
200 {
201 	unsigned long *k;
202 
203 	if (len < cpumask_size())
204 		memset(new_mask, 0, cpumask_size());
205 	else if (len > cpumask_size())
206 		len = cpumask_size();
207 
208 	k = cpumask_bits(new_mask);
209 	return compat_get_bitmap(k, user_mask_ptr, len * 8);
210 }
211 
212 COMPAT_SYSCALL_DEFINE3(sched_setaffinity, compat_pid_t, pid,
213 		       unsigned int, len,
214 		       compat_ulong_t __user *, user_mask_ptr)
215 {
216 	cpumask_var_t new_mask;
217 	int retval;
218 
219 	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
220 		return -ENOMEM;
221 
222 	retval = compat_get_user_cpu_mask(user_mask_ptr, len, new_mask);
223 	if (retval)
224 		goto out;
225 
226 	retval = sched_setaffinity(pid, new_mask);
227 out:
228 	free_cpumask_var(new_mask);
229 	return retval;
230 }
231 
232 COMPAT_SYSCALL_DEFINE3(sched_getaffinity, compat_pid_t,  pid, unsigned int, len,
233 		       compat_ulong_t __user *, user_mask_ptr)
234 {
235 	int ret;
236 	cpumask_var_t mask;
237 
238 	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
239 		return -EINVAL;
240 	if (len & (sizeof(compat_ulong_t)-1))
241 		return -EINVAL;
242 
243 	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
244 		return -ENOMEM;
245 
246 	ret = sched_getaffinity(pid, mask);
247 	if (ret == 0) {
248 		unsigned int retlen = min(len, cpumask_size());
249 
250 		if (compat_put_bitmap(user_mask_ptr, cpumask_bits(mask), retlen * 8))
251 			ret = -EFAULT;
252 		else
253 			ret = retlen;
254 	}
255 	free_cpumask_var(mask);
256 
257 	return ret;
258 }
259 
260 /*
261  * We currently only need the following fields from the sigevent
262  * structure: sigev_value, sigev_signo, sig_notify and (sometimes
263  * sigev_notify_thread_id).  The others are handled in user mode.
264  * We also assume that copying sigev_value.sival_int is sufficient
265  * to keep all the bits of sigev_value.sival_ptr intact.
266  */
267 int get_compat_sigevent(struct sigevent *event,
268 		const struct compat_sigevent __user *u_event)
269 {
270 	memset(event, 0, sizeof(*event));
271 	return (!access_ok(u_event, sizeof(*u_event)) ||
272 		__get_user(event->sigev_value.sival_int,
273 			&u_event->sigev_value.sival_int) ||
274 		__get_user(event->sigev_signo, &u_event->sigev_signo) ||
275 		__get_user(event->sigev_notify, &u_event->sigev_notify) ||
276 		__get_user(event->sigev_notify_thread_id,
277 			&u_event->sigev_notify_thread_id))
278 		? -EFAULT : 0;
279 }
280 
281 long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
282 		       unsigned long bitmap_size)
283 {
284 	unsigned long nr_compat_longs;
285 
286 	/* align bitmap up to nearest compat_long_t boundary */
287 	bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
288 	nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
289 
290 	if (!user_access_begin(umask, bitmap_size / 8))
291 		return -EFAULT;
292 
293 	while (nr_compat_longs > 1) {
294 		compat_ulong_t l1, l2;
295 		unsafe_get_user(l1, umask++, Efault);
296 		unsafe_get_user(l2, umask++, Efault);
297 		*mask++ = ((unsigned long)l2 << BITS_PER_COMPAT_LONG) | l1;
298 		nr_compat_longs -= 2;
299 	}
300 	if (nr_compat_longs)
301 		unsafe_get_user(*mask, umask++, Efault);
302 	user_access_end();
303 	return 0;
304 
305 Efault:
306 	user_access_end();
307 	return -EFAULT;
308 }
309 
310 long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
311 		       unsigned long bitmap_size)
312 {
313 	unsigned long nr_compat_longs;
314 
315 	/* align bitmap up to nearest compat_long_t boundary */
316 	bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
317 	nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
318 
319 	if (!user_access_begin(umask, bitmap_size / 8))
320 		return -EFAULT;
321 
322 	while (nr_compat_longs > 1) {
323 		unsigned long m = *mask++;
324 		unsafe_put_user((compat_ulong_t)m, umask++, Efault);
325 		unsafe_put_user(m >> BITS_PER_COMPAT_LONG, umask++, Efault);
326 		nr_compat_longs -= 2;
327 	}
328 	if (nr_compat_longs)
329 		unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
330 	user_access_end();
331 	return 0;
332 Efault:
333 	user_access_end();
334 	return -EFAULT;
335 }
336 
337 int
338 get_compat_sigset(sigset_t *set, const compat_sigset_t __user *compat)
339 {
340 #ifdef __BIG_ENDIAN
341 	compat_sigset_t v;
342 	if (copy_from_user(&v, compat, sizeof(compat_sigset_t)))
343 		return -EFAULT;
344 	switch (_NSIG_WORDS) {
345 	case 4: set->sig[3] = v.sig[6] | (((long)v.sig[7]) << 32 );
346 		/* fall through */
347 	case 3: set->sig[2] = v.sig[4] | (((long)v.sig[5]) << 32 );
348 		/* fall through */
349 	case 2: set->sig[1] = v.sig[2] | (((long)v.sig[3]) << 32 );
350 		/* fall through */
351 	case 1: set->sig[0] = v.sig[0] | (((long)v.sig[1]) << 32 );
352 	}
353 #else
354 	if (copy_from_user(set, compat, sizeof(compat_sigset_t)))
355 		return -EFAULT;
356 #endif
357 	return 0;
358 }
359 EXPORT_SYMBOL_GPL(get_compat_sigset);
360 
361 /*
362  * Allocate user-space memory for the duration of a single system call,
363  * in order to marshall parameters inside a compat thunk.
364  */
365 void __user *compat_alloc_user_space(unsigned long len)
366 {
367 	void __user *ptr;
368 
369 	/* If len would occupy more than half of the entire compat space... */
370 	if (unlikely(len > (((compat_uptr_t)~0) >> 1)))
371 		return NULL;
372 
373 	ptr = arch_compat_alloc_user_space(len);
374 
375 	if (unlikely(!access_ok(ptr, len)))
376 		return NULL;
377 
378 	return ptr;
379 }
380 EXPORT_SYMBOL_GPL(compat_alloc_user_space);
381