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1/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
4 *
5 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
6 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
7 * 2000-2002 x86-64 support by Andi Kleen
8 */
9#include <linux/sched.h>
10#include <linux/mm.h>
11#include <linux/smp.h>
12#include <linux/kernel.h>
13#include <linux/errno.h>
14#include <linux/wait.h>
15#include <linux/tracehook.h>
16#include <linux/unistd.h>
17#include <linux/stddef.h>
18#include <linux/personality.h>
19#include <linux/uaccess.h>
20#include <linux/user-return-notifier.h>
21#include <linux/uprobes.h>
22
23#include <asm/processor.h>
24#include <asm/ucontext.h>
25#include <asm/i387.h>
26#include <asm/fpu-internal.h>
27#include <asm/vdso.h>
28#include <asm/mce.h>
29#include <asm/sighandling.h>
30
31#ifdef CONFIG_X86_64
32#include <asm/proto.h>
33#include <asm/ia32_unistd.h>
34#include <asm/sys_ia32.h>
35#endif /* CONFIG_X86_64 */
36
37#include <asm/syscall.h>
38#include <asm/syscalls.h>
39
40#include <asm/sigframe.h>
41
42#ifdef CONFIG_X86_32
43# define FIX_EFLAGS (__FIX_EFLAGS | X86_EFLAGS_RF)
44#else
45# define FIX_EFLAGS __FIX_EFLAGS
46#endif
47
48#define COPY(x) do { \
49 get_user_ex(regs->x, &sc->x); \
50} while (0)
51
52#define GET_SEG(seg) ({ \
53 unsigned short tmp; \
54 get_user_ex(tmp, &sc->seg); \
55 tmp; \
56})
57
58#define COPY_SEG(seg) do { \
59 regs->seg = GET_SEG(seg); \
60} while (0)
61
62#define COPY_SEG_CPL3(seg) do { \
63 regs->seg = GET_SEG(seg) | 3; \
64} while (0)
65
66int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
67 unsigned long *pax)
68{
69 void __user *buf;
70 unsigned int tmpflags;
71 unsigned int err = 0;
72
73 /* Always make any pending restarted system calls return -EINTR */
74 current_thread_info()->restart_block.fn = do_no_restart_syscall;
75
76 get_user_try {
77
78#ifdef CONFIG_X86_32
79 set_user_gs(regs, GET_SEG(gs));
80 COPY_SEG(fs);
81 COPY_SEG(es);
82 COPY_SEG(ds);
83#endif /* CONFIG_X86_32 */
84
85 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
86 COPY(dx); COPY(cx); COPY(ip);
87
88#ifdef CONFIG_X86_64
89 COPY(r8);
90 COPY(r9);
91 COPY(r10);
92 COPY(r11);
93 COPY(r12);
94 COPY(r13);
95 COPY(r14);
96 COPY(r15);
97#endif /* CONFIG_X86_64 */
98
99#ifdef CONFIG_X86_32
100 COPY_SEG_CPL3(cs);
101 COPY_SEG_CPL3(ss);
102#else /* !CONFIG_X86_32 */
103 /* Kernel saves and restores only the CS segment register on signals,
104 * which is the bare minimum needed to allow mixed 32/64-bit code.
105 * App's signal handler can save/restore other segments if needed. */
106 COPY_SEG_CPL3(cs);
107#endif /* CONFIG_X86_32 */
108
109 get_user_ex(tmpflags, &sc->flags);
110 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
111 regs->orig_ax = -1; /* disable syscall checks */
112
113 get_user_ex(buf, &sc->fpstate);
114 err |= restore_i387_xstate(buf);
115
116 get_user_ex(*pax, &sc->ax);
117 } get_user_catch(err);
118
119 return err;
120}
121
122int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
123 struct pt_regs *regs, unsigned long mask)
124{
125 int err = 0;
126
127 put_user_try {
128
129#ifdef CONFIG_X86_32
130 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
131 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
132 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
133 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
134#endif /* CONFIG_X86_32 */
135
136 put_user_ex(regs->di, &sc->di);
137 put_user_ex(regs->si, &sc->si);
138 put_user_ex(regs->bp, &sc->bp);
139 put_user_ex(regs->sp, &sc->sp);
140 put_user_ex(regs->bx, &sc->bx);
141 put_user_ex(regs->dx, &sc->dx);
142 put_user_ex(regs->cx, &sc->cx);
143 put_user_ex(regs->ax, &sc->ax);
144#ifdef CONFIG_X86_64
145 put_user_ex(regs->r8, &sc->r8);
146 put_user_ex(regs->r9, &sc->r9);
147 put_user_ex(regs->r10, &sc->r10);
148 put_user_ex(regs->r11, &sc->r11);
149 put_user_ex(regs->r12, &sc->r12);
150 put_user_ex(regs->r13, &sc->r13);
151 put_user_ex(regs->r14, &sc->r14);
152 put_user_ex(regs->r15, &sc->r15);
153#endif /* CONFIG_X86_64 */
154
155 put_user_ex(current->thread.trap_nr, &sc->trapno);
156 put_user_ex(current->thread.error_code, &sc->err);
157 put_user_ex(regs->ip, &sc->ip);
158#ifdef CONFIG_X86_32
159 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
160 put_user_ex(regs->flags, &sc->flags);
161 put_user_ex(regs->sp, &sc->sp_at_signal);
162 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
163#else /* !CONFIG_X86_32 */
164 put_user_ex(regs->flags, &sc->flags);
165 put_user_ex(regs->cs, &sc->cs);
166 put_user_ex(0, &sc->gs);
167 put_user_ex(0, &sc->fs);
168#endif /* CONFIG_X86_32 */
169
170 put_user_ex(fpstate, &sc->fpstate);
171
172 /* non-iBCS2 extensions.. */
173 put_user_ex(mask, &sc->oldmask);
174 put_user_ex(current->thread.cr2, &sc->cr2);
175 } put_user_catch(err);
176
177 return err;
178}
179
180/*
181 * Set up a signal frame.
182 */
183
184/*
185 * Determine which stack to use..
186 */
187static unsigned long align_sigframe(unsigned long sp)
188{
189#ifdef CONFIG_X86_32
190 /*
191 * Align the stack pointer according to the i386 ABI,
192 * i.e. so that on function entry ((sp + 4) & 15) == 0.
193 */
194 sp = ((sp + 4) & -16ul) - 4;
195#else /* !CONFIG_X86_32 */
196 sp = round_down(sp, 16) - 8;
197#endif
198 return sp;
199}
200
201static inline void __user *
202get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
203 void __user **fpstate)
204{
205 /* Default to using normal stack */
206 unsigned long sp = regs->sp;
207 int onsigstack = on_sig_stack(sp);
208
209#ifdef CONFIG_X86_64
210 /* redzone */
211 sp -= 128;
212#endif /* CONFIG_X86_64 */
213
214 if (!onsigstack) {
215 /* This is the X/Open sanctioned signal stack switching. */
216 if (ka->sa.sa_flags & SA_ONSTACK) {
217 if (current->sas_ss_size)
218 sp = current->sas_ss_sp + current->sas_ss_size;
219 } else {
220#ifdef CONFIG_X86_32
221 /* This is the legacy signal stack switching. */
222 if ((regs->ss & 0xffff) != __USER_DS &&
223 !(ka->sa.sa_flags & SA_RESTORER) &&
224 ka->sa.sa_restorer)
225 sp = (unsigned long) ka->sa.sa_restorer;
226#endif /* CONFIG_X86_32 */
227 }
228 }
229
230 if (used_math()) {
231 sp -= sig_xstate_size;
232#ifdef CONFIG_X86_64
233 sp = round_down(sp, 64);
234#endif /* CONFIG_X86_64 */
235 *fpstate = (void __user *)sp;
236 }
237
238 sp = align_sigframe(sp - frame_size);
239
240 /*
241 * If we are on the alternate signal stack and would overflow it, don't.
242 * Return an always-bogus address instead so we will die with SIGSEGV.
243 */
244 if (onsigstack && !likely(on_sig_stack(sp)))
245 return (void __user *)-1L;
246
247 /* save i387 state */
248 if (used_math() && save_i387_xstate(*fpstate) < 0)
249 return (void __user *)-1L;
250
251 return (void __user *)sp;
252}
253
254#ifdef CONFIG_X86_32
255static const struct {
256 u16 poplmovl;
257 u32 val;
258 u16 int80;
259} __attribute__((packed)) retcode = {
260 0xb858, /* popl %eax; movl $..., %eax */
261 __NR_sigreturn,
262 0x80cd, /* int $0x80 */
263};
264
265static const struct {
266 u8 movl;
267 u32 val;
268 u16 int80;
269 u8 pad;
270} __attribute__((packed)) rt_retcode = {
271 0xb8, /* movl $..., %eax */
272 __NR_rt_sigreturn,
273 0x80cd, /* int $0x80 */
274 0
275};
276
277static int
278__setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
279 struct pt_regs *regs)
280{
281 struct sigframe __user *frame;
282 void __user *restorer;
283 int err = 0;
284 void __user *fpstate = NULL;
285
286 frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
287
288 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
289 return -EFAULT;
290
291 if (__put_user(sig, &frame->sig))
292 return -EFAULT;
293
294 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
295 return -EFAULT;
296
297 if (_NSIG_WORDS > 1) {
298 if (__copy_to_user(&frame->extramask, &set->sig[1],
299 sizeof(frame->extramask)))
300 return -EFAULT;
301 }
302
303 if (current->mm->context.vdso)
304 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
305 else
306 restorer = &frame->retcode;
307 if (ka->sa.sa_flags & SA_RESTORER)
308 restorer = ka->sa.sa_restorer;
309
310 /* Set up to return from userspace. */
311 err |= __put_user(restorer, &frame->pretcode);
312
313 /*
314 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
315 *
316 * WE DO NOT USE IT ANY MORE! It's only left here for historical
317 * reasons and because gdb uses it as a signature to notice
318 * signal handler stack frames.
319 */
320 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
321
322 if (err)
323 return -EFAULT;
324
325 /* Set up registers for signal handler */
326 regs->sp = (unsigned long)frame;
327 regs->ip = (unsigned long)ka->sa.sa_handler;
328 regs->ax = (unsigned long)sig;
329 regs->dx = 0;
330 regs->cx = 0;
331
332 regs->ds = __USER_DS;
333 regs->es = __USER_DS;
334 regs->ss = __USER_DS;
335 regs->cs = __USER_CS;
336
337 return 0;
338}
339
340static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
341 sigset_t *set, struct pt_regs *regs)
342{
343 struct rt_sigframe __user *frame;
344 void __user *restorer;
345 int err = 0;
346 void __user *fpstate = NULL;
347
348 frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
349
350 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
351 return -EFAULT;
352
353 put_user_try {
354 put_user_ex(sig, &frame->sig);
355 put_user_ex(&frame->info, &frame->pinfo);
356 put_user_ex(&frame->uc, &frame->puc);
357 err |= copy_siginfo_to_user(&frame->info, info);
358
359 /* Create the ucontext. */
360 if (cpu_has_xsave)
361 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
362 else
363 put_user_ex(0, &frame->uc.uc_flags);
364 put_user_ex(0, &frame->uc.uc_link);
365 put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
366 put_user_ex(sas_ss_flags(regs->sp),
367 &frame->uc.uc_stack.ss_flags);
368 put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
369 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
370 regs, set->sig[0]);
371 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
372
373 /* Set up to return from userspace. */
374 restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
375 if (ka->sa.sa_flags & SA_RESTORER)
376 restorer = ka->sa.sa_restorer;
377 put_user_ex(restorer, &frame->pretcode);
378
379 /*
380 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
381 *
382 * WE DO NOT USE IT ANY MORE! It's only left here for historical
383 * reasons and because gdb uses it as a signature to notice
384 * signal handler stack frames.
385 */
386 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
387 } put_user_catch(err);
388
389 if (err)
390 return -EFAULT;
391
392 /* Set up registers for signal handler */
393 regs->sp = (unsigned long)frame;
394 regs->ip = (unsigned long)ka->sa.sa_handler;
395 regs->ax = (unsigned long)sig;
396 regs->dx = (unsigned long)&frame->info;
397 regs->cx = (unsigned long)&frame->uc;
398
399 regs->ds = __USER_DS;
400 regs->es = __USER_DS;
401 regs->ss = __USER_DS;
402 regs->cs = __USER_CS;
403
404 return 0;
405}
406#else /* !CONFIG_X86_32 */
407static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
408 sigset_t *set, struct pt_regs *regs)
409{
410 struct rt_sigframe __user *frame;
411 void __user *fp = NULL;
412 int err = 0;
413 struct task_struct *me = current;
414
415 frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe), &fp);
416
417 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
418 return -EFAULT;
419
420 if (ka->sa.sa_flags & SA_SIGINFO) {
421 if (copy_siginfo_to_user(&frame->info, info))
422 return -EFAULT;
423 }
424
425 put_user_try {
426 /* Create the ucontext. */
427 if (cpu_has_xsave)
428 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
429 else
430 put_user_ex(0, &frame->uc.uc_flags);
431 put_user_ex(0, &frame->uc.uc_link);
432 put_user_ex(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
433 put_user_ex(sas_ss_flags(regs->sp),
434 &frame->uc.uc_stack.ss_flags);
435 put_user_ex(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
436 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
437 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
438
439 /* Set up to return from userspace. If provided, use a stub
440 already in userspace. */
441 /* x86-64 should always use SA_RESTORER. */
442 if (ka->sa.sa_flags & SA_RESTORER) {
443 put_user_ex(ka->sa.sa_restorer, &frame->pretcode);
444 } else {
445 /* could use a vstub here */
446 err |= -EFAULT;
447 }
448 } put_user_catch(err);
449
450 if (err)
451 return -EFAULT;
452
453 /* Set up registers for signal handler */
454 regs->di = sig;
455 /* In case the signal handler was declared without prototypes */
456 regs->ax = 0;
457
458 /* This also works for non SA_SIGINFO handlers because they expect the
459 next argument after the signal number on the stack. */
460 regs->si = (unsigned long)&frame->info;
461 regs->dx = (unsigned long)&frame->uc;
462 regs->ip = (unsigned long) ka->sa.sa_handler;
463
464 regs->sp = (unsigned long)frame;
465
466 /* Set up the CS register to run signal handlers in 64-bit mode,
467 even if the handler happens to be interrupting 32-bit code. */
468 regs->cs = __USER_CS;
469
470 return 0;
471}
472#endif /* CONFIG_X86_32 */
473
474#ifdef CONFIG_X86_32
475/*
476 * Atomically swap in the new signal mask, and wait for a signal.
477 */
478asmlinkage int
479sys_sigsuspend(int history0, int history1, old_sigset_t mask)
480{
481 sigset_t blocked;
482 siginitset(&blocked, mask);
483 return sigsuspend(&blocked);
484}
485
486asmlinkage int
487sys_sigaction(int sig, const struct old_sigaction __user *act,
488 struct old_sigaction __user *oact)
489{
490 struct k_sigaction new_ka, old_ka;
491 int ret = 0;
492
493 if (act) {
494 old_sigset_t mask;
495
496 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
497 return -EFAULT;
498
499 get_user_try {
500 get_user_ex(new_ka.sa.sa_handler, &act->sa_handler);
501 get_user_ex(new_ka.sa.sa_flags, &act->sa_flags);
502 get_user_ex(mask, &act->sa_mask);
503 get_user_ex(new_ka.sa.sa_restorer, &act->sa_restorer);
504 } get_user_catch(ret);
505
506 if (ret)
507 return -EFAULT;
508 siginitset(&new_ka.sa.sa_mask, mask);
509 }
510
511 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
512
513 if (!ret && oact) {
514 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
515 return -EFAULT;
516
517 put_user_try {
518 put_user_ex(old_ka.sa.sa_handler, &oact->sa_handler);
519 put_user_ex(old_ka.sa.sa_flags, &oact->sa_flags);
520 put_user_ex(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
521 put_user_ex(old_ka.sa.sa_restorer, &oact->sa_restorer);
522 } put_user_catch(ret);
523
524 if (ret)
525 return -EFAULT;
526 }
527
528 return ret;
529}
530#endif /* CONFIG_X86_32 */
531
532long
533sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
534 struct pt_regs *regs)
535{
536 return do_sigaltstack(uss, uoss, regs->sp);
537}
538
539/*
540 * Do a signal return; undo the signal stack.
541 */
542#ifdef CONFIG_X86_32
543unsigned long sys_sigreturn(struct pt_regs *regs)
544{
545 struct sigframe __user *frame;
546 unsigned long ax;
547 sigset_t set;
548
549 frame = (struct sigframe __user *)(regs->sp - 8);
550
551 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
552 goto badframe;
553 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
554 && __copy_from_user(&set.sig[1], &frame->extramask,
555 sizeof(frame->extramask))))
556 goto badframe;
557
558 set_current_blocked(&set);
559
560 if (restore_sigcontext(regs, &frame->sc, &ax))
561 goto badframe;
562 return ax;
563
564badframe:
565 signal_fault(regs, frame, "sigreturn");
566
567 return 0;
568}
569#endif /* CONFIG_X86_32 */
570
571long sys_rt_sigreturn(struct pt_regs *regs)
572{
573 struct rt_sigframe __user *frame;
574 unsigned long ax;
575 sigset_t set;
576
577 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
578 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
579 goto badframe;
580 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
581 goto badframe;
582
583 set_current_blocked(&set);
584
585 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
586 goto badframe;
587
588 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
589 goto badframe;
590
591 return ax;
592
593badframe:
594 signal_fault(regs, frame, "rt_sigreturn");
595 return 0;
596}
597
598/*
599 * OK, we're invoking a handler:
600 */
601static int signr_convert(int sig)
602{
603#ifdef CONFIG_X86_32
604 struct thread_info *info = current_thread_info();
605
606 if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
607 return info->exec_domain->signal_invmap[sig];
608#endif /* CONFIG_X86_32 */
609 return sig;
610}
611
612#ifdef CONFIG_X86_32
613
614#define is_ia32 1
615#define ia32_setup_frame __setup_frame
616#define ia32_setup_rt_frame __setup_rt_frame
617
618#else /* !CONFIG_X86_32 */
619
620#ifdef CONFIG_IA32_EMULATION
621#define is_ia32 test_thread_flag(TIF_IA32)
622#else /* !CONFIG_IA32_EMULATION */
623#define is_ia32 0
624#endif /* CONFIG_IA32_EMULATION */
625
626#ifdef CONFIG_X86_X32_ABI
627#define is_x32 test_thread_flag(TIF_X32)
628
629static int x32_setup_rt_frame(int sig, struct k_sigaction *ka,
630 siginfo_t *info, compat_sigset_t *set,
631 struct pt_regs *regs);
632#else /* !CONFIG_X86_X32_ABI */
633#define is_x32 0
634#endif /* CONFIG_X86_X32_ABI */
635
636int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
637 sigset_t *set, struct pt_regs *regs);
638int ia32_setup_frame(int sig, struct k_sigaction *ka,
639 sigset_t *set, struct pt_regs *regs);
640
641#endif /* CONFIG_X86_32 */
642
643static int
644setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
645 struct pt_regs *regs)
646{
647 int usig = signr_convert(sig);
648 sigset_t *set = sigmask_to_save();
649
650 /* Set up the stack frame */
651 if (is_ia32) {
652 if (ka->sa.sa_flags & SA_SIGINFO)
653 return ia32_setup_rt_frame(usig, ka, info, set, regs);
654 else
655 return ia32_setup_frame(usig, ka, set, regs);
656#ifdef CONFIG_X86_X32_ABI
657 } else if (is_x32) {
658 return x32_setup_rt_frame(usig, ka, info,
659 (compat_sigset_t *)set, regs);
660#endif
661 } else {
662 return __setup_rt_frame(sig, ka, info, set, regs);
663 }
664}
665
666static void
667handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
668 struct pt_regs *regs)
669{
670 /* Are we from a system call? */
671 if (syscall_get_nr(current, regs) >= 0) {
672 /* If so, check system call restarting.. */
673 switch (syscall_get_error(current, regs)) {
674 case -ERESTART_RESTARTBLOCK:
675 case -ERESTARTNOHAND:
676 regs->ax = -EINTR;
677 break;
678
679 case -ERESTARTSYS:
680 if (!(ka->sa.sa_flags & SA_RESTART)) {
681 regs->ax = -EINTR;
682 break;
683 }
684 /* fallthrough */
685 case -ERESTARTNOINTR:
686 regs->ax = regs->orig_ax;
687 regs->ip -= 2;
688 break;
689 }
690 }
691
692 /*
693 * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
694 * flag so that register information in the sigcontext is correct.
695 */
696 if (unlikely(regs->flags & X86_EFLAGS_TF) &&
697 likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
698 regs->flags &= ~X86_EFLAGS_TF;
699
700 if (setup_rt_frame(sig, ka, info, regs) < 0) {
701 force_sigsegv(sig, current);
702 return;
703 }
704
705 /*
706 * Clear the direction flag as per the ABI for function entry.
707 */
708 regs->flags &= ~X86_EFLAGS_DF;
709
710 /*
711 * Clear TF when entering the signal handler, but
712 * notify any tracer that was single-stepping it.
713 * The tracer may want to single-step inside the
714 * handler too.
715 */
716 regs->flags &= ~X86_EFLAGS_TF;
717
718 signal_delivered(sig, info, ka, regs,
719 test_thread_flag(TIF_SINGLESTEP));
720}
721
722#ifdef CONFIG_X86_32
723#define NR_restart_syscall __NR_restart_syscall
724#else /* !CONFIG_X86_32 */
725#define NR_restart_syscall \
726 test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
727#endif /* CONFIG_X86_32 */
728
729/*
730 * Note that 'init' is a special process: it doesn't get signals it doesn't
731 * want to handle. Thus you cannot kill init even with a SIGKILL even by
732 * mistake.
733 */
734static void do_signal(struct pt_regs *regs)
735{
736 struct k_sigaction ka;
737 siginfo_t info;
738 int signr;
739
740 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
741 if (signr > 0) {
742 /* Whee! Actually deliver the signal. */
743 handle_signal(signr, &info, &ka, regs);
744 return;
745 }
746
747 /* Did we come from a system call? */
748 if (syscall_get_nr(current, regs) >= 0) {
749 /* Restart the system call - no handlers present */
750 switch (syscall_get_error(current, regs)) {
751 case -ERESTARTNOHAND:
752 case -ERESTARTSYS:
753 case -ERESTARTNOINTR:
754 regs->ax = regs->orig_ax;
755 regs->ip -= 2;
756 break;
757
758 case -ERESTART_RESTARTBLOCK:
759 regs->ax = NR_restart_syscall;
760 regs->ip -= 2;
761 break;
762 }
763 }
764
765 /*
766 * If there's no signal to deliver, we just put the saved sigmask
767 * back.
768 */
769 restore_saved_sigmask();
770}
771
772/*
773 * notification of userspace execution resumption
774 * - triggered by the TIF_WORK_MASK flags
775 */
776void
777do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
778{
779#ifdef CONFIG_X86_MCE
780 /* notify userspace of pending MCEs */
781 if (thread_info_flags & _TIF_MCE_NOTIFY)
782 mce_notify_process();
783#endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
784
785 if (thread_info_flags & _TIF_UPROBE) {
786 clear_thread_flag(TIF_UPROBE);
787 uprobe_notify_resume(regs);
788 }
789
790 /* deal with pending signal delivery */
791 if (thread_info_flags & _TIF_SIGPENDING)
792 do_signal(regs);
793
794 if (thread_info_flags & _TIF_NOTIFY_RESUME) {
795 clear_thread_flag(TIF_NOTIFY_RESUME);
796 tracehook_notify_resume(regs);
797 }
798 if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
799 fire_user_return_notifiers();
800
801#ifdef CONFIG_X86_32
802 clear_thread_flag(TIF_IRET);
803#endif /* CONFIG_X86_32 */
804}
805
806void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
807{
808 struct task_struct *me = current;
809
810 if (show_unhandled_signals && printk_ratelimit()) {
811 printk("%s"
812 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
813 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
814 me->comm, me->pid, where, frame,
815 regs->ip, regs->sp, regs->orig_ax);
816 print_vma_addr(" in ", regs->ip);
817 printk(KERN_CONT "\n");
818 }
819
820 force_sig(SIGSEGV, me);
821}
822
823#ifdef CONFIG_X86_X32_ABI
824static int x32_setup_rt_frame(int sig, struct k_sigaction *ka,
825 siginfo_t *info, compat_sigset_t *set,
826 struct pt_regs *regs)
827{
828 struct rt_sigframe_x32 __user *frame;
829 void __user *restorer;
830 int err = 0;
831 void __user *fpstate = NULL;
832
833 frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
834
835 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
836 return -EFAULT;
837
838 if (ka->sa.sa_flags & SA_SIGINFO) {
839 if (copy_siginfo_to_user32(&frame->info, info))
840 return -EFAULT;
841 }
842
843 put_user_try {
844 /* Create the ucontext. */
845 if (cpu_has_xsave)
846 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
847 else
848 put_user_ex(0, &frame->uc.uc_flags);
849 put_user_ex(0, &frame->uc.uc_link);
850 put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
851 put_user_ex(sas_ss_flags(regs->sp),
852 &frame->uc.uc_stack.ss_flags);
853 put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
854 put_user_ex(0, &frame->uc.uc__pad0);
855 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
856 regs, set->sig[0]);
857 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
858
859 if (ka->sa.sa_flags & SA_RESTORER) {
860 restorer = ka->sa.sa_restorer;
861 } else {
862 /* could use a vstub here */
863 restorer = NULL;
864 err |= -EFAULT;
865 }
866 put_user_ex(restorer, &frame->pretcode);
867 } put_user_catch(err);
868
869 if (err)
870 return -EFAULT;
871
872 /* Set up registers for signal handler */
873 regs->sp = (unsigned long) frame;
874 regs->ip = (unsigned long) ka->sa.sa_handler;
875
876 /* We use the x32 calling convention here... */
877 regs->di = sig;
878 regs->si = (unsigned long) &frame->info;
879 regs->dx = (unsigned long) &frame->uc;
880
881 loadsegment(ds, __USER_DS);
882 loadsegment(es, __USER_DS);
883
884 regs->cs = __USER_CS;
885 regs->ss = __USER_DS;
886
887 return 0;
888}
889
890asmlinkage long sys32_x32_rt_sigreturn(struct pt_regs *regs)
891{
892 struct rt_sigframe_x32 __user *frame;
893 sigset_t set;
894 unsigned long ax;
895 struct pt_regs tregs;
896
897 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
898
899 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
900 goto badframe;
901 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
902 goto badframe;
903
904 set_current_blocked(&set);
905
906 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
907 goto badframe;
908
909 tregs = *regs;
910 if (sys32_sigaltstack(&frame->uc.uc_stack, NULL, &tregs) == -EFAULT)
911 goto badframe;
912
913 return ax;
914
915badframe:
916 signal_fault(regs, frame, "x32 rt_sigreturn");
917 return 0;
918}
919#endif
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
5 *
6 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
7 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
8 * 2000-2002 x86-64 support by Andi Kleen
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/sched.h>
14#include <linux/sched/task_stack.h>
15#include <linux/mm.h>
16#include <linux/smp.h>
17#include <linux/kernel.h>
18#include <linux/errno.h>
19#include <linux/wait.h>
20#include <linux/tracehook.h>
21#include <linux/unistd.h>
22#include <linux/stddef.h>
23#include <linux/personality.h>
24#include <linux/uaccess.h>
25#include <linux/user-return-notifier.h>
26#include <linux/uprobes.h>
27#include <linux/context_tracking.h>
28#include <linux/entry-common.h>
29#include <linux/syscalls.h>
30
31#include <asm/processor.h>
32#include <asm/ucontext.h>
33#include <asm/fpu/internal.h>
34#include <asm/fpu/signal.h>
35#include <asm/vdso.h>
36#include <asm/mce.h>
37#include <asm/sighandling.h>
38#include <asm/vm86.h>
39
40#ifdef CONFIG_X86_64
41#include <linux/compat.h>
42#include <asm/proto.h>
43#include <asm/ia32_unistd.h>
44#endif /* CONFIG_X86_64 */
45
46#include <asm/syscall.h>
47#include <asm/sigframe.h>
48#include <asm/signal.h>
49
50#ifdef CONFIG_X86_64
51/*
52 * If regs->ss will cause an IRET fault, change it. Otherwise leave it
53 * alone. Using this generally makes no sense unless
54 * user_64bit_mode(regs) would return true.
55 */
56static void force_valid_ss(struct pt_regs *regs)
57{
58 u32 ar;
59 asm volatile ("lar %[old_ss], %[ar]\n\t"
60 "jz 1f\n\t" /* If invalid: */
61 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */
62 "1:"
63 : [ar] "=r" (ar)
64 : [old_ss] "rm" ((u16)regs->ss));
65
66 /*
67 * For a valid 64-bit user context, we need DPL 3, type
68 * read-write data or read-write exp-down data, and S and P
69 * set. We can't use VERW because VERW doesn't check the
70 * P bit.
71 */
72 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
73 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
74 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
75 regs->ss = __USER_DS;
76}
77# define CONTEXT_COPY_SIZE offsetof(struct sigcontext, reserved1)
78#else
79# define CONTEXT_COPY_SIZE sizeof(struct sigcontext)
80#endif
81
82static int restore_sigcontext(struct pt_regs *regs,
83 struct sigcontext __user *usc,
84 unsigned long uc_flags)
85{
86 struct sigcontext sc;
87
88 /* Always make any pending restarted system calls return -EINTR */
89 current->restart_block.fn = do_no_restart_syscall;
90
91 if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE))
92 return -EFAULT;
93
94#ifdef CONFIG_X86_32
95 set_user_gs(regs, sc.gs);
96 regs->fs = sc.fs;
97 regs->es = sc.es;
98 regs->ds = sc.ds;
99#endif /* CONFIG_X86_32 */
100
101 regs->bx = sc.bx;
102 regs->cx = sc.cx;
103 regs->dx = sc.dx;
104 regs->si = sc.si;
105 regs->di = sc.di;
106 regs->bp = sc.bp;
107 regs->ax = sc.ax;
108 regs->sp = sc.sp;
109 regs->ip = sc.ip;
110
111#ifdef CONFIG_X86_64
112 regs->r8 = sc.r8;
113 regs->r9 = sc.r9;
114 regs->r10 = sc.r10;
115 regs->r11 = sc.r11;
116 regs->r12 = sc.r12;
117 regs->r13 = sc.r13;
118 regs->r14 = sc.r14;
119 regs->r15 = sc.r15;
120#endif /* CONFIG_X86_64 */
121
122 /* Get CS/SS and force CPL3 */
123 regs->cs = sc.cs | 0x03;
124 regs->ss = sc.ss | 0x03;
125
126 regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
127 /* disable syscall checks */
128 regs->orig_ax = -1;
129
130#ifdef CONFIG_X86_64
131 /*
132 * Fix up SS if needed for the benefit of old DOSEMU and
133 * CRIU.
134 */
135 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
136 force_valid_ss(regs);
137#endif
138
139 return fpu__restore_sig((void __user *)sc.fpstate,
140 IS_ENABLED(CONFIG_X86_32));
141}
142
143static __always_inline int
144__unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
145 struct pt_regs *regs, unsigned long mask)
146{
147#ifdef CONFIG_X86_32
148 unsafe_put_user(get_user_gs(regs),
149 (unsigned int __user *)&sc->gs, Efault);
150 unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
151 unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
152 unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
153#endif /* CONFIG_X86_32 */
154
155 unsafe_put_user(regs->di, &sc->di, Efault);
156 unsafe_put_user(regs->si, &sc->si, Efault);
157 unsafe_put_user(regs->bp, &sc->bp, Efault);
158 unsafe_put_user(regs->sp, &sc->sp, Efault);
159 unsafe_put_user(regs->bx, &sc->bx, Efault);
160 unsafe_put_user(regs->dx, &sc->dx, Efault);
161 unsafe_put_user(regs->cx, &sc->cx, Efault);
162 unsafe_put_user(regs->ax, &sc->ax, Efault);
163#ifdef CONFIG_X86_64
164 unsafe_put_user(regs->r8, &sc->r8, Efault);
165 unsafe_put_user(regs->r9, &sc->r9, Efault);
166 unsafe_put_user(regs->r10, &sc->r10, Efault);
167 unsafe_put_user(regs->r11, &sc->r11, Efault);
168 unsafe_put_user(regs->r12, &sc->r12, Efault);
169 unsafe_put_user(regs->r13, &sc->r13, Efault);
170 unsafe_put_user(regs->r14, &sc->r14, Efault);
171 unsafe_put_user(regs->r15, &sc->r15, Efault);
172#endif /* CONFIG_X86_64 */
173
174 unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
175 unsafe_put_user(current->thread.error_code, &sc->err, Efault);
176 unsafe_put_user(regs->ip, &sc->ip, Efault);
177#ifdef CONFIG_X86_32
178 unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
179 unsafe_put_user(regs->flags, &sc->flags, Efault);
180 unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
181 unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
182#else /* !CONFIG_X86_32 */
183 unsafe_put_user(regs->flags, &sc->flags, Efault);
184 unsafe_put_user(regs->cs, &sc->cs, Efault);
185 unsafe_put_user(0, &sc->gs, Efault);
186 unsafe_put_user(0, &sc->fs, Efault);
187 unsafe_put_user(regs->ss, &sc->ss, Efault);
188#endif /* CONFIG_X86_32 */
189
190 unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault);
191
192 /* non-iBCS2 extensions.. */
193 unsafe_put_user(mask, &sc->oldmask, Efault);
194 unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
195 return 0;
196Efault:
197 return -EFAULT;
198}
199
200#define unsafe_put_sigcontext(sc, fp, regs, set, label) \
201do { \
202 if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \
203 goto label; \
204} while(0);
205
206#define unsafe_put_sigmask(set, frame, label) \
207 unsafe_put_user(*(__u64 *)(set), \
208 (__u64 __user *)&(frame)->uc.uc_sigmask, \
209 label)
210
211/*
212 * Set up a signal frame.
213 */
214
215/* x86 ABI requires 16-byte alignment */
216#define FRAME_ALIGNMENT 16UL
217
218#define MAX_FRAME_PADDING (FRAME_ALIGNMENT - 1)
219
220/*
221 * Determine which stack to use..
222 */
223static unsigned long align_sigframe(unsigned long sp)
224{
225#ifdef CONFIG_X86_32
226 /*
227 * Align the stack pointer according to the i386 ABI,
228 * i.e. so that on function entry ((sp + 4) & 15) == 0.
229 */
230 sp = ((sp + 4) & -FRAME_ALIGNMENT) - 4;
231#else /* !CONFIG_X86_32 */
232 sp = round_down(sp, FRAME_ALIGNMENT) - 8;
233#endif
234 return sp;
235}
236
237static void __user *
238get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
239 void __user **fpstate)
240{
241 /* Default to using normal stack */
242 bool nested_altstack = on_sig_stack(regs->sp);
243 bool entering_altstack = false;
244 unsigned long math_size = 0;
245 unsigned long sp = regs->sp;
246 unsigned long buf_fx = 0;
247 int ret;
248
249 /* redzone */
250 if (IS_ENABLED(CONFIG_X86_64))
251 sp -= 128;
252
253 /* This is the X/Open sanctioned signal stack switching. */
254 if (ka->sa.sa_flags & SA_ONSTACK) {
255 /*
256 * This checks nested_altstack via sas_ss_flags(). Sensible
257 * programs use SS_AUTODISARM, which disables that check, and
258 * programs that don't use SS_AUTODISARM get compatible.
259 */
260 if (sas_ss_flags(sp) == 0) {
261 sp = current->sas_ss_sp + current->sas_ss_size;
262 entering_altstack = true;
263 }
264 } else if (IS_ENABLED(CONFIG_X86_32) &&
265 !nested_altstack &&
266 regs->ss != __USER_DS &&
267 !(ka->sa.sa_flags & SA_RESTORER) &&
268 ka->sa.sa_restorer) {
269 /* This is the legacy signal stack switching. */
270 sp = (unsigned long) ka->sa.sa_restorer;
271 entering_altstack = true;
272 }
273
274 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
275 &buf_fx, &math_size);
276 *fpstate = (void __user *)sp;
277
278 sp = align_sigframe(sp - frame_size);
279
280 /*
281 * If we are on the alternate signal stack and would overflow it, don't.
282 * Return an always-bogus address instead so we will die with SIGSEGV.
283 */
284 if (unlikely((nested_altstack || entering_altstack) &&
285 !__on_sig_stack(sp))) {
286
287 if (show_unhandled_signals && printk_ratelimit())
288 pr_info("%s[%d] overflowed sigaltstack\n",
289 current->comm, task_pid_nr(current));
290
291 return (void __user *)-1L;
292 }
293
294 /* save i387 and extended state */
295 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size);
296 if (ret < 0)
297 return (void __user *)-1L;
298
299 return (void __user *)sp;
300}
301
302#ifdef CONFIG_X86_32
303static const struct {
304 u16 poplmovl;
305 u32 val;
306 u16 int80;
307} __attribute__((packed)) retcode = {
308 0xb858, /* popl %eax; movl $..., %eax */
309 __NR_sigreturn,
310 0x80cd, /* int $0x80 */
311};
312
313static const struct {
314 u8 movl;
315 u32 val;
316 u16 int80;
317 u8 pad;
318} __attribute__((packed)) rt_retcode = {
319 0xb8, /* movl $..., %eax */
320 __NR_rt_sigreturn,
321 0x80cd, /* int $0x80 */
322 0
323};
324
325static int
326__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
327 struct pt_regs *regs)
328{
329 struct sigframe __user *frame;
330 void __user *restorer;
331 void __user *fp = NULL;
332
333 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
334
335 if (!user_access_begin(frame, sizeof(*frame)))
336 return -EFAULT;
337
338 unsafe_put_user(sig, &frame->sig, Efault);
339 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault);
340 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
341 if (current->mm->context.vdso)
342 restorer = current->mm->context.vdso +
343 vdso_image_32.sym___kernel_sigreturn;
344 else
345 restorer = &frame->retcode;
346 if (ksig->ka.sa.sa_flags & SA_RESTORER)
347 restorer = ksig->ka.sa.sa_restorer;
348
349 /* Set up to return from userspace. */
350 unsafe_put_user(restorer, &frame->pretcode, Efault);
351
352 /*
353 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
354 *
355 * WE DO NOT USE IT ANY MORE! It's only left here for historical
356 * reasons and because gdb uses it as a signature to notice
357 * signal handler stack frames.
358 */
359 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
360 user_access_end();
361
362 /* Set up registers for signal handler */
363 regs->sp = (unsigned long)frame;
364 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
365 regs->ax = (unsigned long)sig;
366 regs->dx = 0;
367 regs->cx = 0;
368
369 regs->ds = __USER_DS;
370 regs->es = __USER_DS;
371 regs->ss = __USER_DS;
372 regs->cs = __USER_CS;
373
374 return 0;
375
376Efault:
377 user_access_end();
378 return -EFAULT;
379}
380
381static int __setup_rt_frame(int sig, struct ksignal *ksig,
382 sigset_t *set, struct pt_regs *regs)
383{
384 struct rt_sigframe __user *frame;
385 void __user *restorer;
386 void __user *fp = NULL;
387
388 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
389
390 if (!user_access_begin(frame, sizeof(*frame)))
391 return -EFAULT;
392
393 unsafe_put_user(sig, &frame->sig, Efault);
394 unsafe_put_user(&frame->info, &frame->pinfo, Efault);
395 unsafe_put_user(&frame->uc, &frame->puc, Efault);
396
397 /* Create the ucontext. */
398 if (static_cpu_has(X86_FEATURE_XSAVE))
399 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
400 else
401 unsafe_put_user(0, &frame->uc.uc_flags, Efault);
402 unsafe_put_user(0, &frame->uc.uc_link, Efault);
403 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
404
405 /* Set up to return from userspace. */
406 restorer = current->mm->context.vdso +
407 vdso_image_32.sym___kernel_rt_sigreturn;
408 if (ksig->ka.sa.sa_flags & SA_RESTORER)
409 restorer = ksig->ka.sa.sa_restorer;
410 unsafe_put_user(restorer, &frame->pretcode, Efault);
411
412 /*
413 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
414 *
415 * WE DO NOT USE IT ANY MORE! It's only left here for historical
416 * reasons and because gdb uses it as a signature to notice
417 * signal handler stack frames.
418 */
419 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
420 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
421 unsafe_put_sigmask(set, frame, Efault);
422 user_access_end();
423
424 if (copy_siginfo_to_user(&frame->info, &ksig->info))
425 return -EFAULT;
426
427 /* Set up registers for signal handler */
428 regs->sp = (unsigned long)frame;
429 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
430 regs->ax = (unsigned long)sig;
431 regs->dx = (unsigned long)&frame->info;
432 regs->cx = (unsigned long)&frame->uc;
433
434 regs->ds = __USER_DS;
435 regs->es = __USER_DS;
436 regs->ss = __USER_DS;
437 regs->cs = __USER_CS;
438
439 return 0;
440Efault:
441 user_access_end();
442 return -EFAULT;
443}
444#else /* !CONFIG_X86_32 */
445static unsigned long frame_uc_flags(struct pt_regs *regs)
446{
447 unsigned long flags;
448
449 if (boot_cpu_has(X86_FEATURE_XSAVE))
450 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
451 else
452 flags = UC_SIGCONTEXT_SS;
453
454 if (likely(user_64bit_mode(regs)))
455 flags |= UC_STRICT_RESTORE_SS;
456
457 return flags;
458}
459
460static int __setup_rt_frame(int sig, struct ksignal *ksig,
461 sigset_t *set, struct pt_regs *regs)
462{
463 struct rt_sigframe __user *frame;
464 void __user *fp = NULL;
465 unsigned long uc_flags;
466
467 /* x86-64 should always use SA_RESTORER. */
468 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
469 return -EFAULT;
470
471 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
472 uc_flags = frame_uc_flags(regs);
473
474 if (!user_access_begin(frame, sizeof(*frame)))
475 return -EFAULT;
476
477 /* Create the ucontext. */
478 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
479 unsafe_put_user(0, &frame->uc.uc_link, Efault);
480 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
481
482 /* Set up to return from userspace. If provided, use a stub
483 already in userspace. */
484 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
485 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
486 unsafe_put_sigmask(set, frame, Efault);
487 user_access_end();
488
489 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
490 if (copy_siginfo_to_user(&frame->info, &ksig->info))
491 return -EFAULT;
492 }
493
494 /* Set up registers for signal handler */
495 regs->di = sig;
496 /* In case the signal handler was declared without prototypes */
497 regs->ax = 0;
498
499 /* This also works for non SA_SIGINFO handlers because they expect the
500 next argument after the signal number on the stack. */
501 regs->si = (unsigned long)&frame->info;
502 regs->dx = (unsigned long)&frame->uc;
503 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
504
505 regs->sp = (unsigned long)frame;
506
507 /*
508 * Set up the CS and SS registers to run signal handlers in
509 * 64-bit mode, even if the handler happens to be interrupting
510 * 32-bit or 16-bit code.
511 *
512 * SS is subtle. In 64-bit mode, we don't need any particular
513 * SS descriptor, but we do need SS to be valid. It's possible
514 * that the old SS is entirely bogus -- this can happen if the
515 * signal we're trying to deliver is #GP or #SS caused by a bad
516 * SS value. We also have a compatibility issue here: DOSEMU
517 * relies on the contents of the SS register indicating the
518 * SS value at the time of the signal, even though that code in
519 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
520 * avoids relying on sigreturn to restore SS; instead it uses
521 * a trampoline.) So we do our best: if the old SS was valid,
522 * we keep it. Otherwise we replace it.
523 */
524 regs->cs = __USER_CS;
525
526 if (unlikely(regs->ss != __USER_DS))
527 force_valid_ss(regs);
528
529 return 0;
530
531Efault:
532 user_access_end();
533 return -EFAULT;
534}
535#endif /* CONFIG_X86_32 */
536
537#ifdef CONFIG_X86_X32_ABI
538static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
539 const struct kernel_siginfo *from)
540{
541 struct compat_siginfo new;
542
543 copy_siginfo_to_external32(&new, from);
544 if (from->si_signo == SIGCHLD) {
545 new._sifields._sigchld_x32._utime = from->si_utime;
546 new._sifields._sigchld_x32._stime = from->si_stime;
547 }
548 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
549 return -EFAULT;
550 return 0;
551}
552
553int copy_siginfo_to_user32(struct compat_siginfo __user *to,
554 const struct kernel_siginfo *from)
555{
556 if (in_x32_syscall())
557 return x32_copy_siginfo_to_user(to, from);
558 return __copy_siginfo_to_user32(to, from);
559}
560#endif /* CONFIG_X86_X32_ABI */
561
562static int x32_setup_rt_frame(struct ksignal *ksig,
563 compat_sigset_t *set,
564 struct pt_regs *regs)
565{
566#ifdef CONFIG_X86_X32_ABI
567 struct rt_sigframe_x32 __user *frame;
568 unsigned long uc_flags;
569 void __user *restorer;
570 void __user *fp = NULL;
571
572 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
573 return -EFAULT;
574
575 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
576
577 uc_flags = frame_uc_flags(regs);
578
579 if (!user_access_begin(frame, sizeof(*frame)))
580 return -EFAULT;
581
582 /* Create the ucontext. */
583 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
584 unsafe_put_user(0, &frame->uc.uc_link, Efault);
585 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
586 unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
587 restorer = ksig->ka.sa.sa_restorer;
588 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
589 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
590 unsafe_put_sigmask(set, frame, Efault);
591 user_access_end();
592
593 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
594 if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
595 return -EFAULT;
596 }
597
598 /* Set up registers for signal handler */
599 regs->sp = (unsigned long) frame;
600 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
601
602 /* We use the x32 calling convention here... */
603 regs->di = ksig->sig;
604 regs->si = (unsigned long) &frame->info;
605 regs->dx = (unsigned long) &frame->uc;
606
607 loadsegment(ds, __USER_DS);
608 loadsegment(es, __USER_DS);
609
610 regs->cs = __USER_CS;
611 regs->ss = __USER_DS;
612#endif /* CONFIG_X86_X32_ABI */
613
614 return 0;
615#ifdef CONFIG_X86_X32_ABI
616Efault:
617 user_access_end();
618 return -EFAULT;
619#endif
620}
621
622/*
623 * Do a signal return; undo the signal stack.
624 */
625#ifdef CONFIG_X86_32
626SYSCALL_DEFINE0(sigreturn)
627{
628 struct pt_regs *regs = current_pt_regs();
629 struct sigframe __user *frame;
630 sigset_t set;
631
632 frame = (struct sigframe __user *)(regs->sp - 8);
633
634 if (!access_ok(frame, sizeof(*frame)))
635 goto badframe;
636 if (__get_user(set.sig[0], &frame->sc.oldmask) ||
637 __get_user(set.sig[1], &frame->extramask[0]))
638 goto badframe;
639
640 set_current_blocked(&set);
641
642 /*
643 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
644 * Save a few cycles by skipping the __get_user.
645 */
646 if (restore_sigcontext(regs, &frame->sc, 0))
647 goto badframe;
648 return regs->ax;
649
650badframe:
651 signal_fault(regs, frame, "sigreturn");
652
653 return 0;
654}
655#endif /* CONFIG_X86_32 */
656
657SYSCALL_DEFINE0(rt_sigreturn)
658{
659 struct pt_regs *regs = current_pt_regs();
660 struct rt_sigframe __user *frame;
661 sigset_t set;
662 unsigned long uc_flags;
663
664 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
665 if (!access_ok(frame, sizeof(*frame)))
666 goto badframe;
667 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
668 goto badframe;
669 if (__get_user(uc_flags, &frame->uc.uc_flags))
670 goto badframe;
671
672 set_current_blocked(&set);
673
674 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
675 goto badframe;
676
677 if (restore_altstack(&frame->uc.uc_stack))
678 goto badframe;
679
680 return regs->ax;
681
682badframe:
683 signal_fault(regs, frame, "rt_sigreturn");
684 return 0;
685}
686
687/*
688 * There are four different struct types for signal frame: sigframe_ia32,
689 * rt_sigframe_ia32, rt_sigframe_x32, and rt_sigframe. Use the worst case
690 * -- the largest size. It means the size for 64-bit apps is a bit more
691 * than needed, but this keeps the code simple.
692 */
693#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
694# define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct sigframe_ia32)
695#else
696# define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct rt_sigframe)
697#endif
698
699/*
700 * The FP state frame contains an XSAVE buffer which must be 64-byte aligned.
701 * If a signal frame starts at an unaligned address, extra space is required.
702 * This is the max alignment padding, conservatively.
703 */
704#define MAX_XSAVE_PADDING 63UL
705
706/*
707 * The frame data is composed of the following areas and laid out as:
708 *
709 * -------------------------
710 * | alignment padding |
711 * -------------------------
712 * | (f)xsave frame |
713 * -------------------------
714 * | fsave header |
715 * -------------------------
716 * | alignment padding |
717 * -------------------------
718 * | siginfo + ucontext |
719 * -------------------------
720 */
721
722/* max_frame_size tells userspace the worst case signal stack size. */
723static unsigned long __ro_after_init max_frame_size;
724
725void __init init_sigframe_size(void)
726{
727 max_frame_size = MAX_FRAME_SIGINFO_UCTXT_SIZE + MAX_FRAME_PADDING;
728
729 max_frame_size += fpu__get_fpstate_size() + MAX_XSAVE_PADDING;
730
731 /* Userspace expects an aligned size. */
732 max_frame_size = round_up(max_frame_size, FRAME_ALIGNMENT);
733
734 pr_info("max sigframe size: %lu\n", max_frame_size);
735}
736
737unsigned long get_sigframe_size(void)
738{
739 return max_frame_size;
740}
741
742static inline int is_ia32_compat_frame(struct ksignal *ksig)
743{
744 return IS_ENABLED(CONFIG_IA32_EMULATION) &&
745 ksig->ka.sa.sa_flags & SA_IA32_ABI;
746}
747
748static inline int is_ia32_frame(struct ksignal *ksig)
749{
750 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
751}
752
753static inline int is_x32_frame(struct ksignal *ksig)
754{
755 return IS_ENABLED(CONFIG_X86_X32_ABI) &&
756 ksig->ka.sa.sa_flags & SA_X32_ABI;
757}
758
759static int
760setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
761{
762 int usig = ksig->sig;
763 sigset_t *set = sigmask_to_save();
764 compat_sigset_t *cset = (compat_sigset_t *) set;
765
766 /* Perform fixup for the pre-signal frame. */
767 rseq_signal_deliver(ksig, regs);
768
769 /* Set up the stack frame */
770 if (is_ia32_frame(ksig)) {
771 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
772 return ia32_setup_rt_frame(usig, ksig, cset, regs);
773 else
774 return ia32_setup_frame(usig, ksig, cset, regs);
775 } else if (is_x32_frame(ksig)) {
776 return x32_setup_rt_frame(ksig, cset, regs);
777 } else {
778 return __setup_rt_frame(ksig->sig, ksig, set, regs);
779 }
780}
781
782static void
783handle_signal(struct ksignal *ksig, struct pt_regs *regs)
784{
785 bool stepping, failed;
786 struct fpu *fpu = ¤t->thread.fpu;
787
788 if (v8086_mode(regs))
789 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
790
791 /* Are we from a system call? */
792 if (syscall_get_nr(current, regs) != -1) {
793 /* If so, check system call restarting.. */
794 switch (syscall_get_error(current, regs)) {
795 case -ERESTART_RESTARTBLOCK:
796 case -ERESTARTNOHAND:
797 regs->ax = -EINTR;
798 break;
799
800 case -ERESTARTSYS:
801 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
802 regs->ax = -EINTR;
803 break;
804 }
805 fallthrough;
806 case -ERESTARTNOINTR:
807 regs->ax = regs->orig_ax;
808 regs->ip -= 2;
809 break;
810 }
811 }
812
813 /*
814 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
815 * so that register information in the sigcontext is correct and
816 * then notify the tracer before entering the signal handler.
817 */
818 stepping = test_thread_flag(TIF_SINGLESTEP);
819 if (stepping)
820 user_disable_single_step(current);
821
822 failed = (setup_rt_frame(ksig, regs) < 0);
823 if (!failed) {
824 /*
825 * Clear the direction flag as per the ABI for function entry.
826 *
827 * Clear RF when entering the signal handler, because
828 * it might disable possible debug exception from the
829 * signal handler.
830 *
831 * Clear TF for the case when it wasn't set by debugger to
832 * avoid the recursive send_sigtrap() in SIGTRAP handler.
833 */
834 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
835 /*
836 * Ensure the signal handler starts with the new fpu state.
837 */
838 fpu__clear_user_states(fpu);
839 }
840 signal_setup_done(failed, ksig, stepping);
841}
842
843static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
844{
845#ifdef CONFIG_IA32_EMULATION
846 if (current->restart_block.arch_data & TS_COMPAT)
847 return __NR_ia32_restart_syscall;
848#endif
849#ifdef CONFIG_X86_X32_ABI
850 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
851#else
852 return __NR_restart_syscall;
853#endif
854}
855
856/*
857 * Note that 'init' is a special process: it doesn't get signals it doesn't
858 * want to handle. Thus you cannot kill init even with a SIGKILL even by
859 * mistake.
860 */
861void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
862{
863 struct ksignal ksig;
864
865 if (has_signal && get_signal(&ksig)) {
866 /* Whee! Actually deliver the signal. */
867 handle_signal(&ksig, regs);
868 return;
869 }
870
871 /* Did we come from a system call? */
872 if (syscall_get_nr(current, regs) != -1) {
873 /* Restart the system call - no handlers present */
874 switch (syscall_get_error(current, regs)) {
875 case -ERESTARTNOHAND:
876 case -ERESTARTSYS:
877 case -ERESTARTNOINTR:
878 regs->ax = regs->orig_ax;
879 regs->ip -= 2;
880 break;
881
882 case -ERESTART_RESTARTBLOCK:
883 regs->ax = get_nr_restart_syscall(regs);
884 regs->ip -= 2;
885 break;
886 }
887 }
888
889 /*
890 * If there's no signal to deliver, we just put the saved sigmask
891 * back.
892 */
893 restore_saved_sigmask();
894}
895
896void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
897{
898 struct task_struct *me = current;
899
900 if (show_unhandled_signals && printk_ratelimit()) {
901 printk("%s"
902 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
903 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
904 me->comm, me->pid, where, frame,
905 regs->ip, regs->sp, regs->orig_ax);
906 print_vma_addr(KERN_CONT " in ", regs->ip);
907 pr_cont("\n");
908 }
909
910 force_sig(SIGSEGV);
911}
912
913#ifdef CONFIG_X86_X32_ABI
914COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
915{
916 struct pt_regs *regs = current_pt_regs();
917 struct rt_sigframe_x32 __user *frame;
918 sigset_t set;
919 unsigned long uc_flags;
920
921 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
922
923 if (!access_ok(frame, sizeof(*frame)))
924 goto badframe;
925 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
926 goto badframe;
927 if (__get_user(uc_flags, &frame->uc.uc_flags))
928 goto badframe;
929
930 set_current_blocked(&set);
931
932 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
933 goto badframe;
934
935 if (compat_restore_altstack(&frame->uc.uc_stack))
936 goto badframe;
937
938 return regs->ax;
939
940badframe:
941 signal_fault(regs, frame, "x32 rt_sigreturn");
942 return 0;
943}
944#endif