aboutsummaryrefslogtreecommitdiffstats
path: root/arch/s390/kernel/compat_signal.c
blob: ef246940b44c514f7c3c101b6b65f20cf20be7df (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
// SPDX-License-Identifier: GPL-2.0
/*
 *    Copyright IBM Corp. 2000, 2006
 *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
 *               Gerhard Tonn (ton@de.ibm.com)                  
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 */

#include <linux/compat.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <asm/ucontext.h>
#include <linux/uaccess.h>
#include <asm/lowcore.h>
#include <asm/switch_to.h>
#include "compat_linux.h"
#include "compat_ptrace.h"
#include "entry.h"

typedef struct 
{
	__u8 callee_used_stack[__SIGNAL_FRAMESIZE32];
	struct sigcontext32 sc;
	_sigregs32 sregs;
	int signo;
	_sigregs_ext32 sregs_ext;
	__u16 svc_insn;		/* Offset of svc_insn is NOT fixed! */
} sigframe32;

typedef struct 
{
	__u8 callee_used_stack[__SIGNAL_FRAMESIZE32];
	__u16 svc_insn;
	compat_siginfo_t info;
	struct ucontext32 uc;
} rt_sigframe32;

int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
{
	int err;

	/* If you change siginfo_t structure, please be sure
	   this code is fixed accordingly.
	   It should never copy any pad contained in the structure
	   to avoid security leaks, but must copy the generic
	   3 ints plus the relevant union member.  
	   This routine must convert siginfo from 64bit to 32bit as well
	   at the same time.  */
	err = __put_user(from->si_signo, &to->si_signo);
	err |= __put_user(from->si_errno, &to->si_errno);
	err |= __put_user(from->si_code, &to->si_code);
	if (from->si_code < 0)
		err |= __copy_to_user(&to->_sifields._pad, &from->_sifields._pad, SI_PAD_SIZE);
	else {
		switch (siginfo_layout(from->si_signo, from->si_code)) {
		case SIL_RT:
			err |= __put_user(from->si_int, &to->si_int);
			/* fallthrough */
		case SIL_KILL:
			err |= __put_user(from->si_pid, &to->si_pid);
			err |= __put_user(from->si_uid, &to->si_uid);
			break;
		case SIL_CHLD:
			err |= __put_user(from->si_pid, &to->si_pid);
			err |= __put_user(from->si_uid, &to->si_uid);
			err |= __put_user(from->si_utime, &to->si_utime);
			err |= __put_user(from->si_stime, &to->si_stime);
			err |= __put_user(from->si_status, &to->si_status);
			break;
		case SIL_FAULT:
			err |= __put_user((unsigned long) from->si_addr,
					  &to->si_addr);
			break;
		case SIL_POLL:
			err |= __put_user(from->si_band, &to->si_band);
			err |= __put_user(from->si_fd, &to->si_fd);
			break;
		case SIL_TIMER:
			err |= __put_user(from->si_tid, &to->si_tid);
			err |= __put_user(from->si_overrun, &to->si_overrun);
			err |= __put_user(from->si_int, &to->si_int);
			break;
		default:
			break;
		}
	}
	return err ? -EFAULT : 0;
}

int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
{
	int err;
	u32 tmp;

	err = __get_user(to->si_signo, &from->si_signo);
	err |= __get_user(to->si_errno, &from->si_errno);
	err |= __get_user(to->si_code, &from->si_code);

	if (to->si_code < 0)
		err |= __copy_from_user(&to->_sifields._pad, &from->_sifields._pad, SI_PAD_SIZE);
	else {
		switch (siginfo_layout(to->si_signo, to->si_code)) {
		case SIL_RT:
			err |= __get_user(to->si_int, &from->si_int);
			/* fallthrough */
		case SIL_KILL:
			err |= __get_user(to->si_pid, &from->si_pid);
			err |= __get_user(to->si_uid, &from->si_uid);
			break;
		case SIL_CHLD:
			err |= __get_user(to->si_pid, &from->si_pid);
			err |= __get_user(to->si_uid, &from->si_uid);
			err |= __get_user(to->si_utime, &from->si_utime);
			err |= __get_user(to->si_stime, &from->si_stime);
			err |= __get_user(to->si_status, &from->si_status);
			break;
		case SIL_FAULT:
			err |= __get_user(tmp, &from->si_addr);
			to->si_addr = (void __force __user *)
				(u64) (tmp & PSW32_ADDR_INSN);
			break;
		case SIL_POLL:
			err |= __get_user(to->si_band, &from->si_band);
			err |= __get_user(to->si_fd, &from->si_fd);
			break;
		case SIL_TIMER:
			err |= __get_user(to->si_tid, &from->si_tid);
			err |= __get_user(to->si_overrun, &from->si_overrun);
			err |= __get_user(to->si_int, &from->si_int);
			break;
		default:
			break;
		}
	}
	return err ? -EFAULT : 0;
}

/* Store registers needed to create the signal frame */
static void store_sigregs(void)
{
	save_access_regs(current->thread.acrs);
	save_fpu_regs();
}

/* Load registers after signal return */
static void load_sigregs(void)
{
	restore_access_regs(current->thread.acrs);
}

static int save_sigregs32(struct pt_regs *regs, _sigregs32 __user *sregs)
{
	_sigregs32 user_sregs;
	int i;

	user_sregs.regs.psw.mask = (__u32)(regs->psw.mask >> 32);
	user_sregs.regs.psw.mask &= PSW32_MASK_USER | PSW32_MASK_RI;
	user_sregs.regs.psw.mask |= PSW32_USER_BITS;
	user_sregs.regs.psw.addr = (__u32) regs->psw.addr |
		(__u32)(regs->psw.mask & PSW_MASK_BA);
	for (i = 0; i < NUM_GPRS; i++)
		user_sregs.regs.gprs[i] = (__u32) regs->gprs[i];
	memcpy(&user_sregs.regs.acrs, current->thread.acrs,
	       sizeof(user_sregs.regs.acrs));
	fpregs_store((_s390_fp_regs *) &user_sregs.fpregs, &current->thread.fpu);
	if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs32)))
		return -EFAULT;
	return 0;
}

static int restore_sigregs32(struct pt_regs *regs,_sigregs32 __user *sregs)
{
	_sigregs32 user_sregs;
	int i;

	/* Alwys make any pending restarted system call return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	if (__copy_from_user(&user_sregs, &sregs->regs, sizeof(user_sregs)))
		return -EFAULT;

	if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW32_MASK_RI))
		return -EINVAL;

	/* Test the floating-point-control word. */
	if (test_fp_ctl(user_sregs.fpregs.fpc))
		return -EINVAL;

	/* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
	regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
		(__u64)(user_sregs.regs.psw.mask & PSW32_MASK_USER) << 32 |
		(__u64)(user_sregs.regs.psw.mask & PSW32_MASK_RI) << 32 |
		(__u64)(user_sregs.regs.psw.addr & PSW32_ADDR_AMODE);
	/* Check for invalid user address space control. */
	if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
		regs->psw.mask = PSW_ASC_PRIMARY |
			(regs->psw.mask & ~PSW_MASK_ASC);
	regs->psw.addr = (__u64)(user_sregs.regs.psw.addr & PSW32_ADDR_INSN);
	for (i = 0; i < NUM_GPRS; i++)
		regs->gprs[i] = (__u64) user_sregs.regs.gprs[i];
	memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
	       sizeof(current->thread.acrs));
	fpregs_load((_s390_fp_regs *) &user_sregs.fpregs, &current->thread.fpu);

	clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
	return 0;
}

static int save_sigregs_ext32(struct pt_regs *regs,
			      _sigregs_ext32 __user *sregs_ext)
{
	__u32 gprs_high[NUM_GPRS];
	__u64 vxrs[__NUM_VXRS_LOW];
	int i;

	/* Save high gprs to signal stack */
	for (i = 0; i < NUM_GPRS; i++)
		gprs_high[i] = regs->gprs[i] >> 32;
	if (__copy_to_user(&sregs_ext->gprs_high, &gprs_high,
			   sizeof(sregs_ext->gprs_high)))
		return -EFAULT;

	/* Save vector registers to signal stack */
	if (MACHINE_HAS_VX) {
		for (i = 0; i < __NUM_VXRS_LOW; i++)
			vxrs[i] = *((__u64 *)(current->thread.fpu.vxrs + i) + 1);
		if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
				   sizeof(sregs_ext->vxrs_low)) ||
		    __copy_to_user(&sregs_ext->vxrs_high,
				   current->thread.fpu.vxrs + __NUM_VXRS_LOW,
				   sizeof(sregs_ext->vxrs_high)))
			return -EFAULT;
	}
	return 0;
}

static int restore_sigregs_ext32(struct pt_regs *regs,
				 _sigregs_ext32 __user *sregs_ext)
{
	__u32 gprs_high[NUM_GPRS];
	__u64 vxrs[__NUM_VXRS_LOW];
	int i;

	/* Restore high gprs from signal stack */
	if (__copy_from_user(&gprs_high, &sregs_ext->gprs_high,
			     sizeof(sregs_ext->gprs_high)))
		return -EFAULT;
	for (i = 0; i < NUM_GPRS; i++)
		*(__u32 *)&regs->gprs[i] = gprs_high[i];

	/* Restore vector registers from signal stack */
	if (MACHINE_HAS_VX) {
		if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
				     sizeof(sregs_ext->vxrs_low)) ||
		    __copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW,
				     &sregs_ext->vxrs_high,
				     sizeof(sregs_ext->vxrs_high)))
			return -EFAULT;
		for (i = 0; i < __NUM_VXRS_LOW; i++)
			*((__u64 *)(current->thread.fpu.vxrs + i) + 1) = vxrs[i];
	}
	return 0;
}

COMPAT_SYSCALL_DEFINE0(sigreturn)
{
	struct pt_regs *regs = task_pt_regs(current);
	sigframe32 __user *frame = (sigframe32 __user *)regs->gprs[15];
	sigset_t set;

	if (get_compat_sigset(&set, (compat_sigset_t __user *)frame->sc.oldmask))
		goto badframe;
	set_current_blocked(&set);
	save_fpu_regs();
	if (restore_sigregs32(regs, &frame->sregs))
		goto badframe;
	if (restore_sigregs_ext32(regs, &frame->sregs_ext))
		goto badframe;
	load_sigregs();
	return regs->gprs[2];
badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
{
	struct pt_regs *regs = task_pt_regs(current);
	rt_sigframe32 __user *frame = (rt_sigframe32 __user *)regs->gprs[15];
	sigset_t set;

	if (get_compat_sigset(&set, &frame->uc.uc_sigmask))
		goto badframe;
	set_current_blocked(&set);
	if (compat_restore_altstack(&frame->uc.uc_stack))
		goto badframe;
	save_fpu_regs();
	if (restore_sigregs32(regs, &frame->uc.uc_mcontext))
		goto badframe;
	if (restore_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))
		goto badframe;
	load_sigregs();
	return regs->gprs[2];
badframe:
	force_sig(SIGSEGV, current);
	return 0;
}	

/*
 * Set up a signal frame.
 */


/*
 * Determine which stack to use..
 */
static inline void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
{
	unsigned long sp;

	/* Default to using normal stack */
	sp = (unsigned long) A(regs->gprs[15]);

	/* Overflow on alternate signal stack gives SIGSEGV. */
	if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
		return (void __user *) -1UL;

	/* This is the X/Open sanctioned signal stack switching.  */
	if (ka->sa.sa_flags & SA_ONSTACK) {
		if (! sas_ss_flags(sp))
			sp = current->sas_ss_sp + current->sas_ss_size;
	}

	return (void __user *)((sp - frame_size) & -8ul);
}

static int setup_frame32(struct ksignal *ksig, sigset_t *set,
			 struct pt_regs *regs)
{
	int sig = ksig->sig;
	sigframe32 __user *frame;
	unsigned long restorer;
	size_t frame_size;

	/*
	 * gprs_high are always present for 31-bit compat tasks.
	 * The space for vector registers is only allocated if
	 * the machine supports it
	 */
	frame_size = sizeof(*frame) - sizeof(frame->sregs_ext.__reserved);
	if (!MACHINE_HAS_VX)
		frame_size -= sizeof(frame->sregs_ext.vxrs_low) +
			      sizeof(frame->sregs_ext.vxrs_high);
	frame = get_sigframe(&ksig->ka, regs, frame_size);
	if (frame == (void __user *) -1UL)
		return -EFAULT;

	/* Set up backchain. */
	if (__put_user(regs->gprs[15], (unsigned int __user *) frame))
		return -EFAULT;

	/* Create struct sigcontext32 on the signal stack */
	if (put_compat_sigset((compat_sigset_t __user *)frame->sc.oldmask,
			      set, sizeof(compat_sigset_t)))
		return -EFAULT;
	if (__put_user(ptr_to_compat(&frame->sc), &frame->sc.sregs))
		return -EFAULT;

	/* Store registers needed to create the signal frame */
	store_sigregs();

	/* Create _sigregs32 on the signal stack */
	if (save_sigregs32(regs, &frame->sregs))
		return -EFAULT;

	/* Place signal number on stack to allow backtrace from handler.  */
	if (__put_user(regs->gprs[2], (int __force __user *) &frame->signo))
		return -EFAULT;

	/* Create _sigregs_ext32 on the signal stack */
	if (save_sigregs_ext32(regs, &frame->sregs_ext))
		return -EFAULT;

	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
		restorer = (unsigned long __force)
			ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE;
	} else {
		/* Signal frames without vectors registers are short ! */
		__u16 __user *svc = (void __user *) frame + frame_size - 2;
		if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc))
			return -EFAULT;
		restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE;
        }

	/* Set up registers for signal handler */
	regs->gprs[14] = restorer;
	regs->gprs[15] = (__force __u64) frame;
	/* Force 31 bit amode and default user address space control. */
	regs->psw.mask = PSW_MASK_BA |
		(PSW_USER_BITS & PSW_MASK_ASC) |
		(regs->psw.mask & ~PSW_MASK_ASC);
	regs->psw.addr = (__force __u64) ksig->ka.sa.sa_handler;

	regs->gprs[2] = sig;
	regs->gprs[3] = (__force __u64) &frame->sc;

	/* We forgot to include these in the sigcontext.
	   To avoid breaking binary compatibility, they are passed as args. */
	if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
	    sig == SIGTRAP || sig == SIGFPE) {
		/* set extra registers only for synchronous signals */
		regs->gprs[4] = regs->int_code & 127;
		regs->gprs[5] = regs->int_parm_long;
		regs->gprs[6] = current->thread.last_break;
	}

	return 0;
}

static int setup_rt_frame32(struct ksignal *ksig, sigset_t *set,
			    struct pt_regs *regs)
{
	rt_sigframe32 __user *frame;
	unsigned long restorer;
	size_t frame_size;
	u32 uc_flags;

	frame_size = sizeof(*frame) -
		     sizeof(frame->uc.uc_mcontext_ext.__reserved);
	/*
	 * gprs_high are always present for 31-bit compat tasks.
	 * The space for vector registers is only allocated if
	 * the machine supports it
	 */
	uc_flags = UC_GPRS_HIGH;
	if (MACHINE_HAS_VX) {
		uc_flags |= UC_VXRS;
	} else
		frame_size -= sizeof(frame->uc.uc_mcontext_ext.vxrs_low) +
			      sizeof(frame->uc.uc_mcontext_ext.vxrs_high);
	frame = get_sigframe(&ksig->ka, regs, frame_size);
	if (frame == (void __user *) -1UL)
		return -EFAULT;

	/* Set up backchain. */
	if (__put_user(regs->gprs[15], (unsigned int __force __user *) frame))
		return -EFAULT;

	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
		restorer = (unsigned long __force)
			ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE;
	} else {
		__u16 __user *svc = &frame->svc_insn;
		if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc))
			return -EFAULT;
		restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE;
	}

	/* Create siginfo on the signal stack */
	if (copy_siginfo_to_user32(&frame->info, &ksig->info))
		return -EFAULT;

	/* Store registers needed to create the signal frame */
	store_sigregs();

	/* Create ucontext on the signal stack. */
	if (__put_user(uc_flags, &frame->uc.uc_flags) ||
	    __put_user(0, &frame->uc.uc_link) ||
	    __compat_save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
	    save_sigregs32(regs, &frame->uc.uc_mcontext) ||
	    put_compat_sigset(&frame->uc.uc_sigmask, set, sizeof(compat_sigset_t)) ||
	    save_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))
		return -EFAULT;

	/* Set up registers for signal handler */
	regs->gprs[14] = restorer;
	regs->gprs[15] = (__force __u64) frame;
	/* Force 31 bit amode and default user address space control. */
	regs->psw.mask = PSW_MASK_BA |
		(PSW_USER_BITS & PSW_MASK_ASC) |
		(regs->psw.mask & ~PSW_MASK_ASC);
	regs->psw.addr = (__u64 __force) ksig->ka.sa.sa_handler;

	regs->gprs[2] = ksig->sig;
	regs->gprs[3] = (__force __u64) &frame->info;
	regs->gprs[4] = (__force __u64) &frame->uc;
	regs->gprs[5] = current->thread.last_break;
	return 0;
}

/*
 * OK, we're invoking a handler
 */	

void handle_signal32(struct ksignal *ksig, sigset_t *oldset,
		     struct pt_regs *regs)
{
	int ret;

	/* Set up the stack frame */
	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
		ret = setup_rt_frame32(ksig, oldset, regs);
	else
		ret = setup_frame32(ksig, oldset, regs);

	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
}