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Remove 'type' argument from access_ok() function
[mirror_ubuntu-focal-kernel.git] / arch / x86 / kernel / signal.c
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 */
74 static 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
97 static 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
160 int 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 */
226 static 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
240 static void __user *
241 get_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 = &current->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
292 static 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
302 static 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
314 static 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(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
378 static 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(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 */
444 static 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
459 static 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(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
538 static 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(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
605 SYSCALL_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) || (_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
630 badframe:
631 signal_fault(regs, frame, "sigreturn");
632
633 return 0;
634 }
635 #endif /* CONFIG_X86_32 */
636
637 SYSCALL_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(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
662 badframe:
663 signal_fault(regs, frame, "rt_sigreturn");
664 return 0;
665 }
666
667 static 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
673 static inline int is_ia32_frame(struct ksignal *ksig)
674 {
675 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
676 }
677
678 static 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
684 static int
685 setup_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 /*
692 * Increment event counter and perform fixup for the pre-signal
693 * frame.
694 */
695 rseq_signal_deliver(ksig, regs);
696
697 /* Set up the stack frame */
698 if (is_ia32_frame(ksig)) {
699 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
700 return ia32_setup_rt_frame(usig, ksig, cset, regs);
701 else
702 return ia32_setup_frame(usig, ksig, cset, regs);
703 } else if (is_x32_frame(ksig)) {
704 return x32_setup_rt_frame(ksig, cset, regs);
705 } else {
706 return __setup_rt_frame(ksig->sig, ksig, set, regs);
707 }
708 }
709
710 static void
711 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
712 {
713 bool stepping, failed;
714 struct fpu *fpu = &current->thread.fpu;
715
716 if (v8086_mode(regs))
717 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
718
719 /* Are we from a system call? */
720 if (syscall_get_nr(current, regs) >= 0) {
721 /* If so, check system call restarting.. */
722 switch (syscall_get_error(current, regs)) {
723 case -ERESTART_RESTARTBLOCK:
724 case -ERESTARTNOHAND:
725 regs->ax = -EINTR;
726 break;
727
728 case -ERESTARTSYS:
729 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
730 regs->ax = -EINTR;
731 break;
732 }
733 /* fallthrough */
734 case -ERESTARTNOINTR:
735 regs->ax = regs->orig_ax;
736 regs->ip -= 2;
737 break;
738 }
739 }
740
741 /*
742 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
743 * so that register information in the sigcontext is correct and
744 * then notify the tracer before entering the signal handler.
745 */
746 stepping = test_thread_flag(TIF_SINGLESTEP);
747 if (stepping)
748 user_disable_single_step(current);
749
750 failed = (setup_rt_frame(ksig, regs) < 0);
751 if (!failed) {
752 /*
753 * Clear the direction flag as per the ABI for function entry.
754 *
755 * Clear RF when entering the signal handler, because
756 * it might disable possible debug exception from the
757 * signal handler.
758 *
759 * Clear TF for the case when it wasn't set by debugger to
760 * avoid the recursive send_sigtrap() in SIGTRAP handler.
761 */
762 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
763 /*
764 * Ensure the signal handler starts with the new fpu state.
765 */
766 if (fpu->initialized)
767 fpu__clear(fpu);
768 }
769 signal_setup_done(failed, ksig, stepping);
770 }
771
772 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
773 {
774 /*
775 * This function is fundamentally broken as currently
776 * implemented.
777 *
778 * The idea is that we want to trigger a call to the
779 * restart_block() syscall and that we want in_ia32_syscall(),
780 * in_x32_syscall(), etc. to match whatever they were in the
781 * syscall being restarted. We assume that the syscall
782 * instruction at (regs->ip - 2) matches whatever syscall
783 * instruction we used to enter in the first place.
784 *
785 * The problem is that we can get here when ptrace pokes
786 * syscall-like values into regs even if we're not in a syscall
787 * at all.
788 *
789 * For now, we maintain historical behavior and guess based on
790 * stored state. We could do better by saving the actual
791 * syscall arch in restart_block or (with caveats on x32) by
792 * checking if regs->ip points to 'int $0x80'. The current
793 * behavior is incorrect if a tracer has a different bitness
794 * than the tracee.
795 */
796 #ifdef CONFIG_IA32_EMULATION
797 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED))
798 return __NR_ia32_restart_syscall;
799 #endif
800 #ifdef CONFIG_X86_X32_ABI
801 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
802 #else
803 return __NR_restart_syscall;
804 #endif
805 }
806
807 /*
808 * Note that 'init' is a special process: it doesn't get signals it doesn't
809 * want to handle. Thus you cannot kill init even with a SIGKILL even by
810 * mistake.
811 */
812 void do_signal(struct pt_regs *regs)
813 {
814 struct ksignal ksig;
815
816 if (get_signal(&ksig)) {
817 /* Whee! Actually deliver the signal. */
818 handle_signal(&ksig, regs);
819 return;
820 }
821
822 /* Did we come from a system call? */
823 if (syscall_get_nr(current, regs) >= 0) {
824 /* Restart the system call - no handlers present */
825 switch (syscall_get_error(current, regs)) {
826 case -ERESTARTNOHAND:
827 case -ERESTARTSYS:
828 case -ERESTARTNOINTR:
829 regs->ax = regs->orig_ax;
830 regs->ip -= 2;
831 break;
832
833 case -ERESTART_RESTARTBLOCK:
834 regs->ax = get_nr_restart_syscall(regs);
835 regs->ip -= 2;
836 break;
837 }
838 }
839
840 /*
841 * If there's no signal to deliver, we just put the saved sigmask
842 * back.
843 */
844 restore_saved_sigmask();
845 }
846
847 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
848 {
849 struct task_struct *me = current;
850
851 if (show_unhandled_signals && printk_ratelimit()) {
852 printk("%s"
853 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
854 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
855 me->comm, me->pid, where, frame,
856 regs->ip, regs->sp, regs->orig_ax);
857 print_vma_addr(KERN_CONT " in ", regs->ip);
858 pr_cont("\n");
859 }
860
861 force_sig(SIGSEGV, me);
862 }
863
864 #ifdef CONFIG_X86_X32_ABI
865 asmlinkage long sys32_x32_rt_sigreturn(void)
866 {
867 struct pt_regs *regs = current_pt_regs();
868 struct rt_sigframe_x32 __user *frame;
869 sigset_t set;
870 unsigned long uc_flags;
871
872 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
873
874 if (!access_ok(frame, sizeof(*frame)))
875 goto badframe;
876 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
877 goto badframe;
878 if (__get_user(uc_flags, &frame->uc.uc_flags))
879 goto badframe;
880
881 set_current_blocked(&set);
882
883 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
884 goto badframe;
885
886 if (compat_restore_altstack(&frame->uc.uc_stack))
887 goto badframe;
888
889 return regs->ax;
890
891 badframe:
892 signal_fault(regs, frame, "x32 rt_sigreturn");
893 return 0;
894 }
895 #endif
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