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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/syscalls.h>
29
30#include <asm/processor.h>
31#include <asm/ucontext.h>
32#include <asm/fpu/internal.h>
33#include <asm/fpu/signal.h>
34#include <asm/vdso.h>
35#include <asm/mce.h>
36#include <asm/sighandling.h>
37#include <asm/vm86.h>
38
39#ifdef CONFIG_X86_64
40#include <asm/proto.h>
41#include <asm/ia32_unistd.h>
42#endif /* CONFIG_X86_64 */
43
44#include <asm/syscall.h>
45#include <asm/syscalls.h>
46
47#include <asm/sigframe.h>
48#include <asm/signal.h>
49
50#define COPY(x) do { \
51 get_user_ex(regs->x, &sc->x); \
52} while (0)
53
54#define GET_SEG(seg) ({ \
55 unsigned short tmp; \
56 get_user_ex(tmp, &sc->seg); \
57 tmp; \
58})
59
60#define COPY_SEG(seg) do { \
61 regs->seg = GET_SEG(seg); \
62} while (0)
63
64#define COPY_SEG_CPL3(seg) do { \
65 regs->seg = GET_SEG(seg) | 3; \
66} while (0)
67
68#ifdef CONFIG_X86_64
69/*
70 * If regs->ss will cause an IRET fault, change it. Otherwise leave it
71 * alone. Using this generally makes no sense unless
72 * user_64bit_mode(regs) would return true.
73 */
74static void force_valid_ss(struct pt_regs *regs)
75{
76 u32 ar;
77 asm volatile ("lar %[old_ss], %[ar]\n\t"
78 "jz 1f\n\t" /* If invalid: */
79 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */
80 "1:"
81 : [ar] "=r" (ar)
82 : [old_ss] "rm" ((u16)regs->ss));
83
84 /*
85 * For a valid 64-bit user context, we need DPL 3, type
86 * read-write data or read-write exp-down data, and S and P
87 * set. We can't use VERW because VERW doesn't check the
88 * P bit.
89 */
90 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
91 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
92 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
93 regs->ss = __USER_DS;
94}
95#endif
96
97static int restore_sigcontext(struct pt_regs *regs,
98 struct sigcontext __user *sc,
99 unsigned long uc_flags)
100{
101 unsigned long buf_val;
102 void __user *buf;
103 unsigned int tmpflags;
104 unsigned int err = 0;
105
106 /* Always make any pending restarted system calls return -EINTR */
107 current->restart_block.fn = do_no_restart_syscall;
108
109 get_user_try {
110
111#ifdef CONFIG_X86_32
112 set_user_gs(regs, GET_SEG(gs));
113 COPY_SEG(fs);
114 COPY_SEG(es);
115 COPY_SEG(ds);
116#endif /* CONFIG_X86_32 */
117
118 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
119 COPY(dx); COPY(cx); COPY(ip); COPY(ax);
120
121#ifdef CONFIG_X86_64
122 COPY(r8);
123 COPY(r9);
124 COPY(r10);
125 COPY(r11);
126 COPY(r12);
127 COPY(r13);
128 COPY(r14);
129 COPY(r15);
130#endif /* CONFIG_X86_64 */
131
132 COPY_SEG_CPL3(cs);
133 COPY_SEG_CPL3(ss);
134
135#ifdef CONFIG_X86_64
136 /*
137 * Fix up SS if needed for the benefit of old DOSEMU and
138 * CRIU.
139 */
140 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) &&
141 user_64bit_mode(regs)))
142 force_valid_ss(regs);
143#endif
144
145 get_user_ex(tmpflags, &sc->flags);
146 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
147 regs->orig_ax = -1; /* disable syscall checks */
148
149 get_user_ex(buf_val, &sc->fpstate);
150 buf = (void __user *)buf_val;
151 } get_user_catch(err);
152
153 err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
154
155 force_iret();
156
157 return err;
158}
159
160int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
161 struct pt_regs *regs, unsigned long mask)
162{
163 int err = 0;
164
165 put_user_try {
166
167#ifdef CONFIG_X86_32
168 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
169 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
170 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
171 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
172#endif /* CONFIG_X86_32 */
173
174 put_user_ex(regs->di, &sc->di);
175 put_user_ex(regs->si, &sc->si);
176 put_user_ex(regs->bp, &sc->bp);
177 put_user_ex(regs->sp, &sc->sp);
178 put_user_ex(regs->bx, &sc->bx);
179 put_user_ex(regs->dx, &sc->dx);
180 put_user_ex(regs->cx, &sc->cx);
181 put_user_ex(regs->ax, &sc->ax);
182#ifdef CONFIG_X86_64
183 put_user_ex(regs->r8, &sc->r8);
184 put_user_ex(regs->r9, &sc->r9);
185 put_user_ex(regs->r10, &sc->r10);
186 put_user_ex(regs->r11, &sc->r11);
187 put_user_ex(regs->r12, &sc->r12);
188 put_user_ex(regs->r13, &sc->r13);
189 put_user_ex(regs->r14, &sc->r14);
190 put_user_ex(regs->r15, &sc->r15);
191#endif /* CONFIG_X86_64 */
192
193 put_user_ex(current->thread.trap_nr, &sc->trapno);
194 put_user_ex(current->thread.error_code, &sc->err);
195 put_user_ex(regs->ip, &sc->ip);
196#ifdef CONFIG_X86_32
197 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
198 put_user_ex(regs->flags, &sc->flags);
199 put_user_ex(regs->sp, &sc->sp_at_signal);
200 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
201#else /* !CONFIG_X86_32 */
202 put_user_ex(regs->flags, &sc->flags);
203 put_user_ex(regs->cs, &sc->cs);
204 put_user_ex(0, &sc->gs);
205 put_user_ex(0, &sc->fs);
206 put_user_ex(regs->ss, &sc->ss);
207#endif /* CONFIG_X86_32 */
208
209 put_user_ex(fpstate, &sc->fpstate);
210
211 /* non-iBCS2 extensions.. */
212 put_user_ex(mask, &sc->oldmask);
213 put_user_ex(current->thread.cr2, &sc->cr2);
214 } put_user_catch(err);
215
216 return err;
217}
218
219/*
220 * Set up a signal frame.
221 */
222
223/*
224 * Determine which stack to use..
225 */
226static unsigned long align_sigframe(unsigned long sp)
227{
228#ifdef CONFIG_X86_32
229 /*
230 * Align the stack pointer according to the i386 ABI,
231 * i.e. so that on function entry ((sp + 4) & 15) == 0.
232 */
233 sp = ((sp + 4) & -16ul) - 4;
234#else /* !CONFIG_X86_32 */
235 sp = round_down(sp, 16) - 8;
236#endif
237 return sp;
238}
239
240static void __user *
241get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
242 void __user **fpstate)
243{
244 /* Default to using normal stack */
245 unsigned long math_size = 0;
246 unsigned long sp = regs->sp;
247 unsigned long buf_fx = 0;
248 int onsigstack = on_sig_stack(sp);
249 struct fpu *fpu = ¤t->thread.fpu;
250
251 /* redzone */
252 if (IS_ENABLED(CONFIG_X86_64))
253 sp -= 128;
254
255 /* This is the X/Open sanctioned signal stack switching. */
256 if (ka->sa.sa_flags & SA_ONSTACK) {
257 if (sas_ss_flags(sp) == 0)
258 sp = current->sas_ss_sp + current->sas_ss_size;
259 } else if (IS_ENABLED(CONFIG_X86_32) &&
260 !onsigstack &&
261 regs->ss != __USER_DS &&
262 !(ka->sa.sa_flags & SA_RESTORER) &&
263 ka->sa.sa_restorer) {
264 /* This is the legacy signal stack switching. */
265 sp = (unsigned long) ka->sa.sa_restorer;
266 }
267
268 if (fpu->initialized) {
269 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
270 &buf_fx, &math_size);
271 *fpstate = (void __user *)sp;
272 }
273
274 sp = align_sigframe(sp - frame_size);
275
276 /*
277 * If we are on the alternate signal stack and would overflow it, don't.
278 * Return an always-bogus address instead so we will die with SIGSEGV.
279 */
280 if (onsigstack && !likely(on_sig_stack(sp)))
281 return (void __user *)-1L;
282
283 /* save i387 and extended state */
284 if (fpu->initialized &&
285 copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0)
286 return (void __user *)-1L;
287
288 return (void __user *)sp;
289}
290
291#ifdef CONFIG_X86_32
292static const struct {
293 u16 poplmovl;
294 u32 val;
295 u16 int80;
296} __attribute__((packed)) retcode = {
297 0xb858, /* popl %eax; movl $..., %eax */
298 __NR_sigreturn,
299 0x80cd, /* int $0x80 */
300};
301
302static const struct {
303 u8 movl;
304 u32 val;
305 u16 int80;
306 u8 pad;
307} __attribute__((packed)) rt_retcode = {
308 0xb8, /* movl $..., %eax */
309 __NR_rt_sigreturn,
310 0x80cd, /* int $0x80 */
311 0
312};
313
314static int
315__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
316 struct pt_regs *regs)
317{
318 struct sigframe __user *frame;
319 void __user *restorer;
320 int err = 0;
321 void __user *fpstate = NULL;
322
323 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
324
325 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
326 return -EFAULT;
327
328 if (__put_user(sig, &frame->sig))
329 return -EFAULT;
330
331 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
332 return -EFAULT;
333
334 if (_NSIG_WORDS > 1) {
335 if (__copy_to_user(&frame->extramask, &set->sig[1],
336 sizeof(frame->extramask)))
337 return -EFAULT;
338 }
339
340 if (current->mm->context.vdso)
341 restorer = current->mm->context.vdso +
342 vdso_image_32.sym___kernel_sigreturn;
343 else
344 restorer = &frame->retcode;
345 if (ksig->ka.sa.sa_flags & SA_RESTORER)
346 restorer = ksig->ka.sa.sa_restorer;
347
348 /* Set up to return from userspace. */
349 err |= __put_user(restorer, &frame->pretcode);
350
351 /*
352 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
353 *
354 * WE DO NOT USE IT ANY MORE! It's only left here for historical
355 * reasons and because gdb uses it as a signature to notice
356 * signal handler stack frames.
357 */
358 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
359
360 if (err)
361 return -EFAULT;
362
363 /* Set up registers for signal handler */
364 regs->sp = (unsigned long)frame;
365 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
366 regs->ax = (unsigned long)sig;
367 regs->dx = 0;
368 regs->cx = 0;
369
370 regs->ds = __USER_DS;
371 regs->es = __USER_DS;
372 regs->ss = __USER_DS;
373 regs->cs = __USER_CS;
374
375 return 0;
376}
377
378static int __setup_rt_frame(int sig, struct ksignal *ksig,
379 sigset_t *set, struct pt_regs *regs)
380{
381 struct rt_sigframe __user *frame;
382 void __user *restorer;
383 int err = 0;
384 void __user *fpstate = NULL;
385
386 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
387
388 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
389 return -EFAULT;
390
391 put_user_try {
392 put_user_ex(sig, &frame->sig);
393 put_user_ex(&frame->info, &frame->pinfo);
394 put_user_ex(&frame->uc, &frame->puc);
395
396 /* Create the ucontext. */
397 if (boot_cpu_has(X86_FEATURE_XSAVE))
398 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
399 else
400 put_user_ex(0, &frame->uc.uc_flags);
401 put_user_ex(0, &frame->uc.uc_link);
402 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
403
404 /* Set up to return from userspace. */
405 restorer = current->mm->context.vdso +
406 vdso_image_32.sym___kernel_rt_sigreturn;
407 if (ksig->ka.sa.sa_flags & SA_RESTORER)
408 restorer = ksig->ka.sa.sa_restorer;
409 put_user_ex(restorer, &frame->pretcode);
410
411 /*
412 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
413 *
414 * WE DO NOT USE IT ANY MORE! It's only left here for historical
415 * reasons and because gdb uses it as a signature to notice
416 * signal handler stack frames.
417 */
418 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
419 } put_user_catch(err);
420
421 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
422 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
423 regs, set->sig[0]);
424 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
425
426 if (err)
427 return -EFAULT;
428
429 /* Set up registers for signal handler */
430 regs->sp = (unsigned long)frame;
431 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
432 regs->ax = (unsigned long)sig;
433 regs->dx = (unsigned long)&frame->info;
434 regs->cx = (unsigned long)&frame->uc;
435
436 regs->ds = __USER_DS;
437 regs->es = __USER_DS;
438 regs->ss = __USER_DS;
439 regs->cs = __USER_CS;
440
441 return 0;
442}
443#else /* !CONFIG_X86_32 */
444static unsigned long frame_uc_flags(struct pt_regs *regs)
445{
446 unsigned long flags;
447
448 if (boot_cpu_has(X86_FEATURE_XSAVE))
449 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
450 else
451 flags = UC_SIGCONTEXT_SS;
452
453 if (likely(user_64bit_mode(regs)))
454 flags |= UC_STRICT_RESTORE_SS;
455
456 return flags;
457}
458
459static int __setup_rt_frame(int sig, struct ksignal *ksig,
460 sigset_t *set, struct pt_regs *regs)
461{
462 struct rt_sigframe __user *frame;
463 void __user *fp = NULL;
464 int err = 0;
465
466 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
467
468 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
469 return -EFAULT;
470
471 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
472 if (copy_siginfo_to_user(&frame->info, &ksig->info))
473 return -EFAULT;
474 }
475
476 put_user_try {
477 /* Create the ucontext. */
478 put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
479 put_user_ex(0, &frame->uc.uc_link);
480 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
481
482 /* Set up to return from userspace. If provided, use a stub
483 already in userspace. */
484 /* x86-64 should always use SA_RESTORER. */
485 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
486 put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
487 } else {
488 /* could use a vstub here */
489 err |= -EFAULT;
490 }
491 } put_user_catch(err);
492
493 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
494 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
495
496 if (err)
497 return -EFAULT;
498
499 /* Set up registers for signal handler */
500 regs->di = sig;
501 /* In case the signal handler was declared without prototypes */
502 regs->ax = 0;
503
504 /* This also works for non SA_SIGINFO handlers because they expect the
505 next argument after the signal number on the stack. */
506 regs->si = (unsigned long)&frame->info;
507 regs->dx = (unsigned long)&frame->uc;
508 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
509
510 regs->sp = (unsigned long)frame;
511
512 /*
513 * Set up the CS and SS registers to run signal handlers in
514 * 64-bit mode, even if the handler happens to be interrupting
515 * 32-bit or 16-bit code.
516 *
517 * SS is subtle. In 64-bit mode, we don't need any particular
518 * SS descriptor, but we do need SS to be valid. It's possible
519 * that the old SS is entirely bogus -- this can happen if the
520 * signal we're trying to deliver is #GP or #SS caused by a bad
521 * SS value. We also have a compatbility issue here: DOSEMU
522 * relies on the contents of the SS register indicating the
523 * SS value at the time of the signal, even though that code in
524 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
525 * avoids relying on sigreturn to restore SS; instead it uses
526 * a trampoline.) So we do our best: if the old SS was valid,
527 * we keep it. Otherwise we replace it.
528 */
529 regs->cs = __USER_CS;
530
531 if (unlikely(regs->ss != __USER_DS))
532 force_valid_ss(regs);
533
534 return 0;
535}
536#endif /* CONFIG_X86_32 */
537
538static int x32_setup_rt_frame(struct ksignal *ksig,
539 compat_sigset_t *set,
540 struct pt_regs *regs)
541{
542#ifdef CONFIG_X86_X32_ABI
543 struct rt_sigframe_x32 __user *frame;
544 void __user *restorer;
545 int err = 0;
546 void __user *fpstate = NULL;
547
548 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
549
550 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
551 return -EFAULT;
552
553 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
554 if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true))
555 return -EFAULT;
556 }
557
558 put_user_try {
559 /* Create the ucontext. */
560 put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
561 put_user_ex(0, &frame->uc.uc_link);
562 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
563 put_user_ex(0, &frame->uc.uc__pad0);
564
565 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
566 restorer = ksig->ka.sa.sa_restorer;
567 } else {
568 /* could use a vstub here */
569 restorer = NULL;
570 err |= -EFAULT;
571 }
572 put_user_ex(restorer, &frame->pretcode);
573 } put_user_catch(err);
574
575 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
576 regs, set->sig[0]);
577 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
578
579 if (err)
580 return -EFAULT;
581
582 /* Set up registers for signal handler */
583 regs->sp = (unsigned long) frame;
584 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
585
586 /* We use the x32 calling convention here... */
587 regs->di = ksig->sig;
588 regs->si = (unsigned long) &frame->info;
589 regs->dx = (unsigned long) &frame->uc;
590
591 loadsegment(ds, __USER_DS);
592 loadsegment(es, __USER_DS);
593
594 regs->cs = __USER_CS;
595 regs->ss = __USER_DS;
596#endif /* CONFIG_X86_X32_ABI */
597
598 return 0;
599}
600
601/*
602 * Do a signal return; undo the signal stack.
603 */
604#ifdef CONFIG_X86_32
605SYSCALL_DEFINE0(sigreturn)
606{
607 struct pt_regs *regs = current_pt_regs();
608 struct sigframe __user *frame;
609 sigset_t set;
610
611 frame = (struct sigframe __user *)(regs->sp - 8);
612
613 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
614 goto badframe;
615 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
616 && __copy_from_user(&set.sig[1], &frame->extramask,
617 sizeof(frame->extramask))))
618 goto badframe;
619
620 set_current_blocked(&set);
621
622 /*
623 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
624 * Save a few cycles by skipping the __get_user.
625 */
626 if (restore_sigcontext(regs, &frame->sc, 0))
627 goto badframe;
628 return regs->ax;
629
630badframe:
631 signal_fault(regs, frame, "sigreturn");
632
633 return 0;
634}
635#endif /* CONFIG_X86_32 */
636
637SYSCALL_DEFINE0(rt_sigreturn)
638{
639 struct pt_regs *regs = current_pt_regs();
640 struct rt_sigframe __user *frame;
641 sigset_t set;
642 unsigned long uc_flags;
643
644 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
645 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
646 goto badframe;
647 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
648 goto badframe;
649 if (__get_user(uc_flags, &frame->uc.uc_flags))
650 goto badframe;
651
652 set_current_blocked(&set);
653
654 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
655 goto badframe;
656
657 if (restore_altstack(&frame->uc.uc_stack))
658 goto badframe;
659
660 return regs->ax;
661
662badframe:
663 signal_fault(regs, frame, "rt_sigreturn");
664 return 0;
665}
666
667static inline int is_ia32_compat_frame(struct ksignal *ksig)
668{
669 return IS_ENABLED(CONFIG_IA32_EMULATION) &&
670 ksig->ka.sa.sa_flags & SA_IA32_ABI;
671}
672
673static inline int is_ia32_frame(struct ksignal *ksig)
674{
675 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
676}
677
678static inline int is_x32_frame(struct ksignal *ksig)
679{
680 return IS_ENABLED(CONFIG_X86_X32_ABI) &&
681 ksig->ka.sa.sa_flags & SA_X32_ABI;
682}
683
684static int
685setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
686{
687 int usig = ksig->sig;
688 sigset_t *set = sigmask_to_save();
689 compat_sigset_t *cset = (compat_sigset_t *) set;
690
691 /* Set up the stack frame */
692 if (is_ia32_frame(ksig)) {
693 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
694 return ia32_setup_rt_frame(usig, ksig, cset, regs);
695 else
696 return ia32_setup_frame(usig, ksig, cset, regs);
697 } else if (is_x32_frame(ksig)) {
698 return x32_setup_rt_frame(ksig, cset, regs);
699 } else {
700 return __setup_rt_frame(ksig->sig, ksig, set, regs);
701 }
702}
703
704static void
705handle_signal(struct ksignal *ksig, struct pt_regs *regs)
706{
707 bool stepping, failed;
708 struct fpu *fpu = ¤t->thread.fpu;
709
710 if (v8086_mode(regs))
711 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
712
713 /* Are we from a system call? */
714 if (syscall_get_nr(current, regs) >= 0) {
715 /* If so, check system call restarting.. */
716 switch (syscall_get_error(current, regs)) {
717 case -ERESTART_RESTARTBLOCK:
718 case -ERESTARTNOHAND:
719 regs->ax = -EINTR;
720 break;
721
722 case -ERESTARTSYS:
723 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
724 regs->ax = -EINTR;
725 break;
726 }
727 /* fallthrough */
728 case -ERESTARTNOINTR:
729 regs->ax = regs->orig_ax;
730 regs->ip -= 2;
731 break;
732 }
733 }
734
735 /*
736 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
737 * so that register information in the sigcontext is correct and
738 * then notify the tracer before entering the signal handler.
739 */
740 stepping = test_thread_flag(TIF_SINGLESTEP);
741 if (stepping)
742 user_disable_single_step(current);
743
744 failed = (setup_rt_frame(ksig, regs) < 0);
745 if (!failed) {
746 /*
747 * Clear the direction flag as per the ABI for function entry.
748 *
749 * Clear RF when entering the signal handler, because
750 * it might disable possible debug exception from the
751 * signal handler.
752 *
753 * Clear TF for the case when it wasn't set by debugger to
754 * avoid the recursive send_sigtrap() in SIGTRAP handler.
755 */
756 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
757 /*
758 * Ensure the signal handler starts with the new fpu state.
759 */
760 if (fpu->initialized)
761 fpu__clear(fpu);
762 }
763 signal_setup_done(failed, ksig, stepping);
764}
765
766static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
767{
768 /*
769 * This function is fundamentally broken as currently
770 * implemented.
771 *
772 * The idea is that we want to trigger a call to the
773 * restart_block() syscall and that we want in_ia32_syscall(),
774 * in_x32_syscall(), etc. to match whatever they were in the
775 * syscall being restarted. We assume that the syscall
776 * instruction at (regs->ip - 2) matches whatever syscall
777 * instruction we used to enter in the first place.
778 *
779 * The problem is that we can get here when ptrace pokes
780 * syscall-like values into regs even if we're not in a syscall
781 * at all.
782 *
783 * For now, we maintain historical behavior and guess based on
784 * stored state. We could do better by saving the actual
785 * syscall arch in restart_block or (with caveats on x32) by
786 * checking if regs->ip points to 'int $0x80'. The current
787 * behavior is incorrect if a tracer has a different bitness
788 * than the tracee.
789 */
790#ifdef CONFIG_IA32_EMULATION
791 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED))
792 return __NR_ia32_restart_syscall;
793#endif
794#ifdef CONFIG_X86_X32_ABI
795 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
796#else
797 return __NR_restart_syscall;
798#endif
799}
800
801/*
802 * Note that 'init' is a special process: it doesn't get signals it doesn't
803 * want to handle. Thus you cannot kill init even with a SIGKILL even by
804 * mistake.
805 */
806void do_signal(struct pt_regs *regs)
807{
808 struct ksignal ksig;
809
810 if (get_signal(&ksig)) {
811 /* Whee! Actually deliver the signal. */
812 handle_signal(&ksig, regs);
813 return;
814 }
815
816 /* Did we come from a system call? */
817 if (syscall_get_nr(current, regs) >= 0) {
818 /* Restart the system call - no handlers present */
819 switch (syscall_get_error(current, regs)) {
820 case -ERESTARTNOHAND:
821 case -ERESTARTSYS:
822 case -ERESTARTNOINTR:
823 regs->ax = regs->orig_ax;
824 regs->ip -= 2;
825 break;
826
827 case -ERESTART_RESTARTBLOCK:
828 regs->ax = get_nr_restart_syscall(regs);
829 regs->ip -= 2;
830 break;
831 }
832 }
833
834 /*
835 * If there's no signal to deliver, we just put the saved sigmask
836 * back.
837 */
838 restore_saved_sigmask();
839}
840
841void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
842{
843 struct task_struct *me = current;
844
845 if (show_unhandled_signals && printk_ratelimit()) {
846 printk("%s"
847 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
848 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
849 me->comm, me->pid, where, frame,
850 regs->ip, regs->sp, regs->orig_ax);
851 print_vma_addr(KERN_CONT " in ", regs->ip);
852 pr_cont("\n");
853 }
854
855 force_sig(SIGSEGV, me);
856}
857
858#ifdef CONFIG_X86_X32_ABI
859asmlinkage long sys32_x32_rt_sigreturn(void)
860{
861 struct pt_regs *regs = current_pt_regs();
862 struct rt_sigframe_x32 __user *frame;
863 sigset_t set;
864 unsigned long uc_flags;
865
866 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
867
868 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
869 goto badframe;
870 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
871 goto badframe;
872 if (__get_user(uc_flags, &frame->uc.uc_flags))
873 goto badframe;
874
875 set_current_blocked(&set);
876
877 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
878 goto badframe;
879
880 if (compat_restore_altstack(&frame->uc.uc_stack))
881 goto badframe;
882
883 return regs->ax;
884
885badframe:
886 signal_fault(regs, frame, "x32 rt_sigreturn");
887 return 0;
888}
889#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/*
216 * Determine which stack to use..
217 */
218static unsigned long align_sigframe(unsigned long sp)
219{
220#ifdef CONFIG_X86_32
221 /*
222 * Align the stack pointer according to the i386 ABI,
223 * i.e. so that on function entry ((sp + 4) & 15) == 0.
224 */
225 sp = ((sp + 4) & -16ul) - 4;
226#else /* !CONFIG_X86_32 */
227 sp = round_down(sp, 16) - 8;
228#endif
229 return sp;
230}
231
232static void __user *
233get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
234 void __user **fpstate)
235{
236 /* Default to using normal stack */
237 unsigned long math_size = 0;
238 unsigned long sp = regs->sp;
239 unsigned long buf_fx = 0;
240 int onsigstack = on_sig_stack(sp);
241 int ret;
242
243 /* redzone */
244 if (IS_ENABLED(CONFIG_X86_64))
245 sp -= 128;
246
247 /* This is the X/Open sanctioned signal stack switching. */
248 if (ka->sa.sa_flags & SA_ONSTACK) {
249 if (sas_ss_flags(sp) == 0)
250 sp = current->sas_ss_sp + current->sas_ss_size;
251 } else if (IS_ENABLED(CONFIG_X86_32) &&
252 !onsigstack &&
253 regs->ss != __USER_DS &&
254 !(ka->sa.sa_flags & SA_RESTORER) &&
255 ka->sa.sa_restorer) {
256 /* This is the legacy signal stack switching. */
257 sp = (unsigned long) ka->sa.sa_restorer;
258 }
259
260 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
261 &buf_fx, &math_size);
262 *fpstate = (void __user *)sp;
263
264 sp = align_sigframe(sp - frame_size);
265
266 /*
267 * If we are on the alternate signal stack and would overflow it, don't.
268 * Return an always-bogus address instead so we will die with SIGSEGV.
269 */
270 if (onsigstack && !likely(on_sig_stack(sp)))
271 return (void __user *)-1L;
272
273 /* save i387 and extended state */
274 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size);
275 if (ret < 0)
276 return (void __user *)-1L;
277
278 return (void __user *)sp;
279}
280
281#ifdef CONFIG_X86_32
282static const struct {
283 u16 poplmovl;
284 u32 val;
285 u16 int80;
286} __attribute__((packed)) retcode = {
287 0xb858, /* popl %eax; movl $..., %eax */
288 __NR_sigreturn,
289 0x80cd, /* int $0x80 */
290};
291
292static const struct {
293 u8 movl;
294 u32 val;
295 u16 int80;
296 u8 pad;
297} __attribute__((packed)) rt_retcode = {
298 0xb8, /* movl $..., %eax */
299 __NR_rt_sigreturn,
300 0x80cd, /* int $0x80 */
301 0
302};
303
304static int
305__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
306 struct pt_regs *regs)
307{
308 struct sigframe __user *frame;
309 void __user *restorer;
310 void __user *fp = NULL;
311
312 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
313
314 if (!user_access_begin(frame, sizeof(*frame)))
315 return -EFAULT;
316
317 unsafe_put_user(sig, &frame->sig, Efault);
318 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault);
319 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
320 if (current->mm->context.vdso)
321 restorer = current->mm->context.vdso +
322 vdso_image_32.sym___kernel_sigreturn;
323 else
324 restorer = &frame->retcode;
325 if (ksig->ka.sa.sa_flags & SA_RESTORER)
326 restorer = ksig->ka.sa.sa_restorer;
327
328 /* Set up to return from userspace. */
329 unsafe_put_user(restorer, &frame->pretcode, Efault);
330
331 /*
332 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
333 *
334 * WE DO NOT USE IT ANY MORE! It's only left here for historical
335 * reasons and because gdb uses it as a signature to notice
336 * signal handler stack frames.
337 */
338 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
339 user_access_end();
340
341 /* Set up registers for signal handler */
342 regs->sp = (unsigned long)frame;
343 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
344 regs->ax = (unsigned long)sig;
345 regs->dx = 0;
346 regs->cx = 0;
347
348 regs->ds = __USER_DS;
349 regs->es = __USER_DS;
350 regs->ss = __USER_DS;
351 regs->cs = __USER_CS;
352
353 return 0;
354
355Efault:
356 user_access_end();
357 return -EFAULT;
358}
359
360static int __setup_rt_frame(int sig, struct ksignal *ksig,
361 sigset_t *set, struct pt_regs *regs)
362{
363 struct rt_sigframe __user *frame;
364 void __user *restorer;
365 void __user *fp = NULL;
366
367 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
368
369 if (!user_access_begin(frame, sizeof(*frame)))
370 return -EFAULT;
371
372 unsafe_put_user(sig, &frame->sig, Efault);
373 unsafe_put_user(&frame->info, &frame->pinfo, Efault);
374 unsafe_put_user(&frame->uc, &frame->puc, Efault);
375
376 /* Create the ucontext. */
377 if (static_cpu_has(X86_FEATURE_XSAVE))
378 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
379 else
380 unsafe_put_user(0, &frame->uc.uc_flags, Efault);
381 unsafe_put_user(0, &frame->uc.uc_link, Efault);
382 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
383
384 /* Set up to return from userspace. */
385 restorer = current->mm->context.vdso +
386 vdso_image_32.sym___kernel_rt_sigreturn;
387 if (ksig->ka.sa.sa_flags & SA_RESTORER)
388 restorer = ksig->ka.sa.sa_restorer;
389 unsafe_put_user(restorer, &frame->pretcode, Efault);
390
391 /*
392 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
393 *
394 * WE DO NOT USE IT ANY MORE! It's only left here for historical
395 * reasons and because gdb uses it as a signature to notice
396 * signal handler stack frames.
397 */
398 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
399 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
400 unsafe_put_sigmask(set, frame, Efault);
401 user_access_end();
402
403 if (copy_siginfo_to_user(&frame->info, &ksig->info))
404 return -EFAULT;
405
406 /* Set up registers for signal handler */
407 regs->sp = (unsigned long)frame;
408 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
409 regs->ax = (unsigned long)sig;
410 regs->dx = (unsigned long)&frame->info;
411 regs->cx = (unsigned long)&frame->uc;
412
413 regs->ds = __USER_DS;
414 regs->es = __USER_DS;
415 regs->ss = __USER_DS;
416 regs->cs = __USER_CS;
417
418 return 0;
419Efault:
420 user_access_end();
421 return -EFAULT;
422}
423#else /* !CONFIG_X86_32 */
424static unsigned long frame_uc_flags(struct pt_regs *regs)
425{
426 unsigned long flags;
427
428 if (boot_cpu_has(X86_FEATURE_XSAVE))
429 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
430 else
431 flags = UC_SIGCONTEXT_SS;
432
433 if (likely(user_64bit_mode(regs)))
434 flags |= UC_STRICT_RESTORE_SS;
435
436 return flags;
437}
438
439static int __setup_rt_frame(int sig, struct ksignal *ksig,
440 sigset_t *set, struct pt_regs *regs)
441{
442 struct rt_sigframe __user *frame;
443 void __user *fp = NULL;
444 unsigned long uc_flags;
445
446 /* x86-64 should always use SA_RESTORER. */
447 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
448 return -EFAULT;
449
450 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
451 uc_flags = frame_uc_flags(regs);
452
453 if (!user_access_begin(frame, sizeof(*frame)))
454 return -EFAULT;
455
456 /* Create the ucontext. */
457 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
458 unsafe_put_user(0, &frame->uc.uc_link, Efault);
459 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
460
461 /* Set up to return from userspace. If provided, use a stub
462 already in userspace. */
463 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
464 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
465 unsafe_put_sigmask(set, frame, Efault);
466 user_access_end();
467
468 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
469 if (copy_siginfo_to_user(&frame->info, &ksig->info))
470 return -EFAULT;
471 }
472
473 /* Set up registers for signal handler */
474 regs->di = sig;
475 /* In case the signal handler was declared without prototypes */
476 regs->ax = 0;
477
478 /* This also works for non SA_SIGINFO handlers because they expect the
479 next argument after the signal number on the stack. */
480 regs->si = (unsigned long)&frame->info;
481 regs->dx = (unsigned long)&frame->uc;
482 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
483
484 regs->sp = (unsigned long)frame;
485
486 /*
487 * Set up the CS and SS registers to run signal handlers in
488 * 64-bit mode, even if the handler happens to be interrupting
489 * 32-bit or 16-bit code.
490 *
491 * SS is subtle. In 64-bit mode, we don't need any particular
492 * SS descriptor, but we do need SS to be valid. It's possible
493 * that the old SS is entirely bogus -- this can happen if the
494 * signal we're trying to deliver is #GP or #SS caused by a bad
495 * SS value. We also have a compatbility issue here: DOSEMU
496 * relies on the contents of the SS register indicating the
497 * SS value at the time of the signal, even though that code in
498 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
499 * avoids relying on sigreturn to restore SS; instead it uses
500 * a trampoline.) So we do our best: if the old SS was valid,
501 * we keep it. Otherwise we replace it.
502 */
503 regs->cs = __USER_CS;
504
505 if (unlikely(regs->ss != __USER_DS))
506 force_valid_ss(regs);
507
508 return 0;
509
510Efault:
511 user_access_end();
512 return -EFAULT;
513}
514#endif /* CONFIG_X86_32 */
515
516#ifdef CONFIG_X86_X32_ABI
517static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
518 const struct kernel_siginfo *from)
519{
520 struct compat_siginfo new;
521
522 copy_siginfo_to_external32(&new, from);
523 if (from->si_signo == SIGCHLD) {
524 new._sifields._sigchld_x32._utime = from->si_utime;
525 new._sifields._sigchld_x32._stime = from->si_stime;
526 }
527 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
528 return -EFAULT;
529 return 0;
530}
531
532int copy_siginfo_to_user32(struct compat_siginfo __user *to,
533 const struct kernel_siginfo *from)
534{
535 if (in_x32_syscall())
536 return x32_copy_siginfo_to_user(to, from);
537 return __copy_siginfo_to_user32(to, from);
538}
539#endif /* CONFIG_X86_X32_ABI */
540
541static int x32_setup_rt_frame(struct ksignal *ksig,
542 compat_sigset_t *set,
543 struct pt_regs *regs)
544{
545#ifdef CONFIG_X86_X32_ABI
546 struct rt_sigframe_x32 __user *frame;
547 unsigned long uc_flags;
548 void __user *restorer;
549 void __user *fp = NULL;
550
551 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
552 return -EFAULT;
553
554 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
555
556 uc_flags = frame_uc_flags(regs);
557
558 if (!user_access_begin(frame, sizeof(*frame)))
559 return -EFAULT;
560
561 /* Create the ucontext. */
562 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
563 unsafe_put_user(0, &frame->uc.uc_link, Efault);
564 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
565 unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
566 restorer = ksig->ka.sa.sa_restorer;
567 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
568 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
569 unsafe_put_sigmask(set, frame, Efault);
570 user_access_end();
571
572 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
573 if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
574 return -EFAULT;
575 }
576
577 /* Set up registers for signal handler */
578 regs->sp = (unsigned long) frame;
579 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
580
581 /* We use the x32 calling convention here... */
582 regs->di = ksig->sig;
583 regs->si = (unsigned long) &frame->info;
584 regs->dx = (unsigned long) &frame->uc;
585
586 loadsegment(ds, __USER_DS);
587 loadsegment(es, __USER_DS);
588
589 regs->cs = __USER_CS;
590 regs->ss = __USER_DS;
591#endif /* CONFIG_X86_X32_ABI */
592
593 return 0;
594#ifdef CONFIG_X86_X32_ABI
595Efault:
596 user_access_end();
597 return -EFAULT;
598#endif
599}
600
601/*
602 * Do a signal return; undo the signal stack.
603 */
604#ifdef CONFIG_X86_32
605SYSCALL_DEFINE0(sigreturn)
606{
607 struct pt_regs *regs = current_pt_regs();
608 struct sigframe __user *frame;
609 sigset_t set;
610
611 frame = (struct sigframe __user *)(regs->sp - 8);
612
613 if (!access_ok(frame, sizeof(*frame)))
614 goto badframe;
615 if (__get_user(set.sig[0], &frame->sc.oldmask) ||
616 __get_user(set.sig[1], &frame->extramask[0]))
617 goto badframe;
618
619 set_current_blocked(&set);
620
621 /*
622 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
623 * Save a few cycles by skipping the __get_user.
624 */
625 if (restore_sigcontext(regs, &frame->sc, 0))
626 goto badframe;
627 return regs->ax;
628
629badframe:
630 signal_fault(regs, frame, "sigreturn");
631
632 return 0;
633}
634#endif /* CONFIG_X86_32 */
635
636SYSCALL_DEFINE0(rt_sigreturn)
637{
638 struct pt_regs *regs = current_pt_regs();
639 struct rt_sigframe __user *frame;
640 sigset_t set;
641 unsigned long uc_flags;
642
643 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
644 if (!access_ok(frame, sizeof(*frame)))
645 goto badframe;
646 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
647 goto badframe;
648 if (__get_user(uc_flags, &frame->uc.uc_flags))
649 goto badframe;
650
651 set_current_blocked(&set);
652
653 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
654 goto badframe;
655
656 if (restore_altstack(&frame->uc.uc_stack))
657 goto badframe;
658
659 return regs->ax;
660
661badframe:
662 signal_fault(regs, frame, "rt_sigreturn");
663 return 0;
664}
665
666static inline int is_ia32_compat_frame(struct ksignal *ksig)
667{
668 return IS_ENABLED(CONFIG_IA32_EMULATION) &&
669 ksig->ka.sa.sa_flags & SA_IA32_ABI;
670}
671
672static inline int is_ia32_frame(struct ksignal *ksig)
673{
674 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
675}
676
677static inline int is_x32_frame(struct ksignal *ksig)
678{
679 return IS_ENABLED(CONFIG_X86_X32_ABI) &&
680 ksig->ka.sa.sa_flags & SA_X32_ABI;
681}
682
683static int
684setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
685{
686 int usig = ksig->sig;
687 sigset_t *set = sigmask_to_save();
688 compat_sigset_t *cset = (compat_sigset_t *) set;
689
690 /* Perform fixup for the pre-signal frame. */
691 rseq_signal_deliver(ksig, regs);
692
693 /* Set up the stack frame */
694 if (is_ia32_frame(ksig)) {
695 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
696 return ia32_setup_rt_frame(usig, ksig, cset, regs);
697 else
698 return ia32_setup_frame(usig, ksig, cset, regs);
699 } else if (is_x32_frame(ksig)) {
700 return x32_setup_rt_frame(ksig, cset, regs);
701 } else {
702 return __setup_rt_frame(ksig->sig, ksig, set, regs);
703 }
704}
705
706static void
707handle_signal(struct ksignal *ksig, struct pt_regs *regs)
708{
709 bool stepping, failed;
710 struct fpu *fpu = ¤t->thread.fpu;
711
712 if (v8086_mode(regs))
713 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
714
715 /* Are we from a system call? */
716 if (syscall_get_nr(current, regs) >= 0) {
717 /* If so, check system call restarting.. */
718 switch (syscall_get_error(current, regs)) {
719 case -ERESTART_RESTARTBLOCK:
720 case -ERESTARTNOHAND:
721 regs->ax = -EINTR;
722 break;
723
724 case -ERESTARTSYS:
725 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
726 regs->ax = -EINTR;
727 break;
728 }
729 fallthrough;
730 case -ERESTARTNOINTR:
731 regs->ax = regs->orig_ax;
732 regs->ip -= 2;
733 break;
734 }
735 }
736
737 /*
738 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
739 * so that register information in the sigcontext is correct and
740 * then notify the tracer before entering the signal handler.
741 */
742 stepping = test_thread_flag(TIF_SINGLESTEP);
743 if (stepping)
744 user_disable_single_step(current);
745
746 failed = (setup_rt_frame(ksig, regs) < 0);
747 if (!failed) {
748 /*
749 * Clear the direction flag as per the ABI for function entry.
750 *
751 * Clear RF when entering the signal handler, because
752 * it might disable possible debug exception from the
753 * signal handler.
754 *
755 * Clear TF for the case when it wasn't set by debugger to
756 * avoid the recursive send_sigtrap() in SIGTRAP handler.
757 */
758 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
759 /*
760 * Ensure the signal handler starts with the new fpu state.
761 */
762 fpu__clear_user_states(fpu);
763 }
764 signal_setup_done(failed, ksig, stepping);
765}
766
767static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
768{
769 /*
770 * This function is fundamentally broken as currently
771 * implemented.
772 *
773 * The idea is that we want to trigger a call to the
774 * restart_block() syscall and that we want in_ia32_syscall(),
775 * in_x32_syscall(), etc. to match whatever they were in the
776 * syscall being restarted. We assume that the syscall
777 * instruction at (regs->ip - 2) matches whatever syscall
778 * instruction we used to enter in the first place.
779 *
780 * The problem is that we can get here when ptrace pokes
781 * syscall-like values into regs even if we're not in a syscall
782 * at all.
783 *
784 * For now, we maintain historical behavior and guess based on
785 * stored state. We could do better by saving the actual
786 * syscall arch in restart_block or (with caveats on x32) by
787 * checking if regs->ip points to 'int $0x80'. The current
788 * behavior is incorrect if a tracer has a different bitness
789 * than the tracee.
790 */
791#ifdef CONFIG_IA32_EMULATION
792 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED))
793 return __NR_ia32_restart_syscall;
794#endif
795#ifdef CONFIG_X86_X32_ABI
796 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
797#else
798 return __NR_restart_syscall;
799#endif
800}
801
802/*
803 * Note that 'init' is a special process: it doesn't get signals it doesn't
804 * want to handle. Thus you cannot kill init even with a SIGKILL even by
805 * mistake.
806 */
807void arch_do_signal(struct pt_regs *regs)
808{
809 struct ksignal ksig;
810
811 if (get_signal(&ksig)) {
812 /* Whee! Actually deliver the signal. */
813 handle_signal(&ksig, regs);
814 return;
815 }
816
817 /* Did we come from a system call? */
818 if (syscall_get_nr(current, regs) >= 0) {
819 /* Restart the system call - no handlers present */
820 switch (syscall_get_error(current, regs)) {
821 case -ERESTARTNOHAND:
822 case -ERESTARTSYS:
823 case -ERESTARTNOINTR:
824 regs->ax = regs->orig_ax;
825 regs->ip -= 2;
826 break;
827
828 case -ERESTART_RESTARTBLOCK:
829 regs->ax = get_nr_restart_syscall(regs);
830 regs->ip -= 2;
831 break;
832 }
833 }
834
835 /*
836 * If there's no signal to deliver, we just put the saved sigmask
837 * back.
838 */
839 restore_saved_sigmask();
840}
841
842void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
843{
844 struct task_struct *me = current;
845
846 if (show_unhandled_signals && printk_ratelimit()) {
847 printk("%s"
848 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
849 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
850 me->comm, me->pid, where, frame,
851 regs->ip, regs->sp, regs->orig_ax);
852 print_vma_addr(KERN_CONT " in ", regs->ip);
853 pr_cont("\n");
854 }
855
856 force_sig(SIGSEGV);
857}
858
859#ifdef CONFIG_X86_X32_ABI
860COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
861{
862 struct pt_regs *regs = current_pt_regs();
863 struct rt_sigframe_x32 __user *frame;
864 sigset_t set;
865 unsigned long uc_flags;
866
867 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
868
869 if (!access_ok(frame, sizeof(*frame)))
870 goto badframe;
871 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
872 goto badframe;
873 if (__get_user(uc_flags, &frame->uc.uc_flags))
874 goto badframe;
875
876 set_current_blocked(&set);
877
878 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
879 goto badframe;
880
881 if (compat_restore_altstack(&frame->uc.uc_stack))
882 goto badframe;
883
884 return regs->ax;
885
886badframe:
887 signal_fault(regs, frame, "x32 rt_sigreturn");
888 return 0;
889}
890#endif