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 */
force_valid_ss(struct pt_regs * regs)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
restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc,unsigned long uc_flags)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 get_user_ex(tmpflags, &sc->flags);
136 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
137 regs->orig_ax = -1; /* disable syscall checks */
138
139 get_user_ex(buf_val, &sc->fpstate);
140 buf = (void __user *)buf_val;
141 } get_user_catch(err);
142
143 #ifdef CONFIG_X86_64
144 /*
145 * Fix up SS if needed for the benefit of old DOSEMU and
146 * CRIU.
147 */
148 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
149 force_valid_ss(regs);
150 #endif
151
152 err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
153
154 force_iret();
155
156 return err;
157 }
158
setup_sigcontext(struct sigcontext __user * sc,void __user * fpstate,struct pt_regs * regs,unsigned long mask)159 int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
160 struct pt_regs *regs, unsigned long mask)
161 {
162 int err = 0;
163
164 put_user_try {
165
166 #ifdef CONFIG_X86_32
167 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
168 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
169 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
170 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
171 #endif /* CONFIG_X86_32 */
172
173 put_user_ex(regs->di, &sc->di);
174 put_user_ex(regs->si, &sc->si);
175 put_user_ex(regs->bp, &sc->bp);
176 put_user_ex(regs->sp, &sc->sp);
177 put_user_ex(regs->bx, &sc->bx);
178 put_user_ex(regs->dx, &sc->dx);
179 put_user_ex(regs->cx, &sc->cx);
180 put_user_ex(regs->ax, &sc->ax);
181 #ifdef CONFIG_X86_64
182 put_user_ex(regs->r8, &sc->r8);
183 put_user_ex(regs->r9, &sc->r9);
184 put_user_ex(regs->r10, &sc->r10);
185 put_user_ex(regs->r11, &sc->r11);
186 put_user_ex(regs->r12, &sc->r12);
187 put_user_ex(regs->r13, &sc->r13);
188 put_user_ex(regs->r14, &sc->r14);
189 put_user_ex(regs->r15, &sc->r15);
190 #endif /* CONFIG_X86_64 */
191
192 put_user_ex(current->thread.trap_nr, &sc->trapno);
193 put_user_ex(current->thread.error_code, &sc->err);
194 put_user_ex(regs->ip, &sc->ip);
195 #ifdef CONFIG_X86_32
196 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
197 put_user_ex(regs->flags, &sc->flags);
198 put_user_ex(regs->sp, &sc->sp_at_signal);
199 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
200 #else /* !CONFIG_X86_32 */
201 put_user_ex(regs->flags, &sc->flags);
202 put_user_ex(regs->cs, &sc->cs);
203 put_user_ex(0, &sc->gs);
204 put_user_ex(0, &sc->fs);
205 put_user_ex(regs->ss, &sc->ss);
206 #endif /* CONFIG_X86_32 */
207
208 put_user_ex(fpstate, (unsigned long __user *)&sc->fpstate);
209
210 /* non-iBCS2 extensions.. */
211 put_user_ex(mask, &sc->oldmask);
212 put_user_ex(current->thread.cr2, &sc->cr2);
213 } put_user_catch(err);
214
215 return err;
216 }
217
218 /*
219 * Set up a signal frame.
220 */
221
222 /*
223 * Determine which stack to use..
224 */
align_sigframe(unsigned long sp)225 static unsigned long align_sigframe(unsigned long sp)
226 {
227 #ifdef CONFIG_X86_32
228 /*
229 * Align the stack pointer according to the i386 ABI,
230 * i.e. so that on function entry ((sp + 4) & 15) == 0.
231 */
232 sp = ((sp + 4) & -16ul) - 4;
233 #else /* !CONFIG_X86_32 */
234 sp = round_down(sp, 16) - 8;
235 #endif
236 return sp;
237 }
238
239 static void __user *
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,size_t frame_size,void __user ** fpstate)240 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
241 void __user **fpstate)
242 {
243 /* Default to using normal stack */
244 unsigned long math_size = 0;
245 unsigned long sp = regs->sp;
246 unsigned long buf_fx = 0;
247 int onsigstack = on_sig_stack(sp);
248 int ret;
249
250 /* redzone */
251 if (IS_ENABLED(CONFIG_X86_64))
252 sp -= 128;
253
254 /* This is the X/Open sanctioned signal stack switching. */
255 if (ka->sa.sa_flags & SA_ONSTACK) {
256 if (sas_ss_flags(sp) == 0)
257 sp = current->sas_ss_sp + current->sas_ss_size;
258 } else if (IS_ENABLED(CONFIG_X86_32) &&
259 !onsigstack &&
260 regs->ss != __USER_DS &&
261 !(ka->sa.sa_flags & SA_RESTORER) &&
262 ka->sa.sa_restorer) {
263 /* This is the legacy signal stack switching. */
264 sp = (unsigned long) ka->sa.sa_restorer;
265 }
266
267 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
268 &buf_fx, &math_size);
269 *fpstate = (void __user *)sp;
270
271 sp = align_sigframe(sp - frame_size);
272
273 /*
274 * If we are on the alternate signal stack and would overflow it, don't.
275 * Return an always-bogus address instead so we will die with SIGSEGV.
276 */
277 if (onsigstack && !likely(on_sig_stack(sp)))
278 return (void __user *)-1L;
279
280 /* save i387 and extended state */
281 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size);
282 if (ret < 0)
283 return (void __user *)-1L;
284
285 return (void __user *)sp;
286 }
287
288 #ifdef CONFIG_X86_32
289 static const struct {
290 u16 poplmovl;
291 u32 val;
292 u16 int80;
293 } __attribute__((packed)) retcode = {
294 0xb858, /* popl %eax; movl $..., %eax */
295 __NR_sigreturn,
296 0x80cd, /* int $0x80 */
297 };
298
299 static const struct {
300 u8 movl;
301 u32 val;
302 u16 int80;
303 u8 pad;
304 } __attribute__((packed)) rt_retcode = {
305 0xb8, /* movl $..., %eax */
306 __NR_rt_sigreturn,
307 0x80cd, /* int $0x80 */
308 0
309 };
310
311 static int
__setup_frame(int sig,struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)312 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
313 struct pt_regs *regs)
314 {
315 struct sigframe __user *frame;
316 void __user *restorer;
317 int err = 0;
318 void __user *fpstate = NULL;
319
320 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
321
322 if (!access_ok(frame, sizeof(*frame)))
323 return -EFAULT;
324
325 if (__put_user(sig, &frame->sig))
326 return -EFAULT;
327
328 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
329 return -EFAULT;
330
331 if (_NSIG_WORDS > 1) {
332 if (__copy_to_user(&frame->extramask, &set->sig[1],
333 sizeof(frame->extramask)))
334 return -EFAULT;
335 }
336
337 if (current->mm->context.vdso)
338 restorer = current->mm->context.vdso +
339 vdso_image_32.sym___kernel_sigreturn;
340 else
341 restorer = &frame->retcode;
342 if (ksig->ka.sa.sa_flags & SA_RESTORER)
343 restorer = ksig->ka.sa.sa_restorer;
344
345 /* Set up to return from userspace. */
346 err |= __put_user(restorer, &frame->pretcode);
347
348 /*
349 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
350 *
351 * WE DO NOT USE IT ANY MORE! It's only left here for historical
352 * reasons and because gdb uses it as a signature to notice
353 * signal handler stack frames.
354 */
355 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
356
357 if (err)
358 return -EFAULT;
359
360 /* Set up registers for signal handler */
361 regs->sp = (unsigned long)frame;
362 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
363 regs->ax = (unsigned long)sig;
364 regs->dx = 0;
365 regs->cx = 0;
366
367 regs->ds = __USER_DS;
368 regs->es = __USER_DS;
369 regs->ss = __USER_DS;
370 regs->cs = __USER_CS;
371
372 return 0;
373 }
374
__setup_rt_frame(int sig,struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)375 static int __setup_rt_frame(int sig, struct ksignal *ksig,
376 sigset_t *set, struct pt_regs *regs)
377 {
378 struct rt_sigframe __user *frame;
379 void __user *restorer;
380 int err = 0;
381 void __user *fpstate = NULL;
382
383 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
384
385 if (!access_ok(frame, sizeof(*frame)))
386 return -EFAULT;
387
388 put_user_try {
389 put_user_ex(sig, &frame->sig);
390 put_user_ex(&frame->info, &frame->pinfo);
391 put_user_ex(&frame->uc, &frame->puc);
392
393 /* Create the ucontext. */
394 if (static_cpu_has(X86_FEATURE_XSAVE))
395 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
396 else
397 put_user_ex(0, &frame->uc.uc_flags);
398 put_user_ex(0, &frame->uc.uc_link);
399 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
400
401 /* Set up to return from userspace. */
402 restorer = current->mm->context.vdso +
403 vdso_image_32.sym___kernel_rt_sigreturn;
404 if (ksig->ka.sa.sa_flags & SA_RESTORER)
405 restorer = ksig->ka.sa.sa_restorer;
406 put_user_ex(restorer, &frame->pretcode);
407
408 /*
409 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
410 *
411 * WE DO NOT USE IT ANY MORE! It's only left here for historical
412 * reasons and because gdb uses it as a signature to notice
413 * signal handler stack frames.
414 */
415 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
416 } put_user_catch(err);
417
418 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
419 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
420 regs, set->sig[0]);
421 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
422
423 if (err)
424 return -EFAULT;
425
426 /* Set up registers for signal handler */
427 regs->sp = (unsigned long)frame;
428 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
429 regs->ax = (unsigned long)sig;
430 regs->dx = (unsigned long)&frame->info;
431 regs->cx = (unsigned long)&frame->uc;
432
433 regs->ds = __USER_DS;
434 regs->es = __USER_DS;
435 regs->ss = __USER_DS;
436 regs->cs = __USER_CS;
437
438 return 0;
439 }
440 #else /* !CONFIG_X86_32 */
frame_uc_flags(struct pt_regs * regs)441 static unsigned long frame_uc_flags(struct pt_regs *regs)
442 {
443 unsigned long flags;
444
445 if (boot_cpu_has(X86_FEATURE_XSAVE))
446 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
447 else
448 flags = UC_SIGCONTEXT_SS;
449
450 if (likely(user_64bit_mode(regs)))
451 flags |= UC_STRICT_RESTORE_SS;
452
453 return flags;
454 }
455
__setup_rt_frame(int sig,struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)456 static int __setup_rt_frame(int sig, struct ksignal *ksig,
457 sigset_t *set, struct pt_regs *regs)
458 {
459 struct rt_sigframe __user *frame;
460 void __user *fp = NULL;
461 unsigned long uc_flags;
462 int err = 0;
463
464 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
465
466 if (!access_ok(frame, sizeof(*frame)))
467 return -EFAULT;
468
469 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
470 if (copy_siginfo_to_user(&frame->info, &ksig->info))
471 return -EFAULT;
472 }
473
474 uc_flags = frame_uc_flags(regs);
475
476 put_user_try {
477 /* Create the ucontext. */
478 put_user_ex(uc_flags, &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
x32_setup_rt_frame(struct ksignal * ksig,compat_sigset_t * set,struct pt_regs * regs)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 unsigned long uc_flags;
545 void __user *restorer;
546 int err = 0;
547 void __user *fpstate = NULL;
548
549 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
550
551 if (!access_ok(frame, sizeof(*frame)))
552 return -EFAULT;
553
554 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
555 if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true))
556 return -EFAULT;
557 }
558
559 uc_flags = frame_uc_flags(regs);
560
561 put_user_try {
562 /* Create the ucontext. */
563 put_user_ex(uc_flags, &frame->uc.uc_flags);
564 put_user_ex(0, &frame->uc.uc_link);
565 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
566 put_user_ex(0, &frame->uc.uc__pad0);
567
568 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
569 restorer = ksig->ka.sa.sa_restorer;
570 } else {
571 /* could use a vstub here */
572 restorer = NULL;
573 err |= -EFAULT;
574 }
575 put_user_ex(restorer, (unsigned long __user *)&frame->pretcode);
576 } put_user_catch(err);
577
578 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
579 regs, set->sig[0]);
580 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
581
582 if (err)
583 return -EFAULT;
584
585 /* Set up registers for signal handler */
586 regs->sp = (unsigned long) frame;
587 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
588
589 /* We use the x32 calling convention here... */
590 regs->di = ksig->sig;
591 regs->si = (unsigned long) &frame->info;
592 regs->dx = (unsigned long) &frame->uc;
593
594 loadsegment(ds, __USER_DS);
595 loadsegment(es, __USER_DS);
596
597 regs->cs = __USER_CS;
598 regs->ss = __USER_DS;
599 #endif /* CONFIG_X86_X32_ABI */
600
601 return 0;
602 }
603
604 /*
605 * Do a signal return; undo the signal stack.
606 */
607 #ifdef CONFIG_X86_32
SYSCALL_DEFINE0(sigreturn)608 SYSCALL_DEFINE0(sigreturn)
609 {
610 struct pt_regs *regs = current_pt_regs();
611 struct sigframe __user *frame;
612 sigset_t set;
613
614 frame = (struct sigframe __user *)(regs->sp - 8);
615
616 if (!access_ok(frame, sizeof(*frame)))
617 goto badframe;
618 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
619 && __copy_from_user(&set.sig[1], &frame->extramask,
620 sizeof(frame->extramask))))
621 goto badframe;
622
623 set_current_blocked(&set);
624
625 /*
626 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
627 * Save a few cycles by skipping the __get_user.
628 */
629 if (restore_sigcontext(regs, &frame->sc, 0))
630 goto badframe;
631 return regs->ax;
632
633 badframe:
634 signal_fault(regs, frame, "sigreturn");
635
636 return 0;
637 }
638 #endif /* CONFIG_X86_32 */
639
SYSCALL_DEFINE0(rt_sigreturn)640 SYSCALL_DEFINE0(rt_sigreturn)
641 {
642 struct pt_regs *regs = current_pt_regs();
643 struct rt_sigframe __user *frame;
644 sigset_t set;
645 unsigned long uc_flags;
646
647 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
648 if (!access_ok(frame, sizeof(*frame)))
649 goto badframe;
650 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
651 goto badframe;
652 if (__get_user(uc_flags, &frame->uc.uc_flags))
653 goto badframe;
654
655 set_current_blocked(&set);
656
657 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
658 goto badframe;
659
660 if (restore_altstack(&frame->uc.uc_stack))
661 goto badframe;
662
663 return regs->ax;
664
665 badframe:
666 signal_fault(regs, frame, "rt_sigreturn");
667 return 0;
668 }
669
is_ia32_compat_frame(struct ksignal * ksig)670 static inline int is_ia32_compat_frame(struct ksignal *ksig)
671 {
672 return IS_ENABLED(CONFIG_IA32_EMULATION) &&
673 ksig->ka.sa.sa_flags & SA_IA32_ABI;
674 }
675
is_ia32_frame(struct ksignal * ksig)676 static inline int is_ia32_frame(struct ksignal *ksig)
677 {
678 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
679 }
680
is_x32_frame(struct ksignal * ksig)681 static inline int is_x32_frame(struct ksignal *ksig)
682 {
683 return IS_ENABLED(CONFIG_X86_X32_ABI) &&
684 ksig->ka.sa.sa_flags & SA_X32_ABI;
685 }
686
687 static int
setup_rt_frame(struct ksignal * ksig,struct pt_regs * regs)688 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
689 {
690 int usig = ksig->sig;
691 sigset_t *set = sigmask_to_save();
692 compat_sigset_t *cset = (compat_sigset_t *) set;
693
694 /* Perform fixup for the pre-signal frame. */
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
handle_signal(struct ksignal * ksig,struct pt_regs * regs)711 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
712 {
713 bool stepping, failed;
714 struct fpu *fpu = ¤t->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 fpu__clear(fpu);
767 }
768 signal_setup_done(failed, ksig, stepping);
769 }
770
get_nr_restart_syscall(const struct pt_regs * regs)771 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
772 {
773 /*
774 * This function is fundamentally broken as currently
775 * implemented.
776 *
777 * The idea is that we want to trigger a call to the
778 * restart_block() syscall and that we want in_ia32_syscall(),
779 * in_x32_syscall(), etc. to match whatever they were in the
780 * syscall being restarted. We assume that the syscall
781 * instruction at (regs->ip - 2) matches whatever syscall
782 * instruction we used to enter in the first place.
783 *
784 * The problem is that we can get here when ptrace pokes
785 * syscall-like values into regs even if we're not in a syscall
786 * at all.
787 *
788 * For now, we maintain historical behavior and guess based on
789 * stored state. We could do better by saving the actual
790 * syscall arch in restart_block or (with caveats on x32) by
791 * checking if regs->ip points to 'int $0x80'. The current
792 * behavior is incorrect if a tracer has a different bitness
793 * than the tracee.
794 */
795 #ifdef CONFIG_IA32_EMULATION
796 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED))
797 return __NR_ia32_restart_syscall;
798 #endif
799 #ifdef CONFIG_X86_X32_ABI
800 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
801 #else
802 return __NR_restart_syscall;
803 #endif
804 }
805
806 /*
807 * Note that 'init' is a special process: it doesn't get signals it doesn't
808 * want to handle. Thus you cannot kill init even with a SIGKILL even by
809 * mistake.
810 */
do_signal(struct pt_regs * regs)811 void do_signal(struct pt_regs *regs)
812 {
813 struct ksignal ksig;
814
815 if (get_signal(&ksig)) {
816 /* Whee! Actually deliver the signal. */
817 handle_signal(&ksig, regs);
818 return;
819 }
820
821 /* Did we come from a system call? */
822 if (syscall_get_nr(current, regs) >= 0) {
823 /* Restart the system call - no handlers present */
824 switch (syscall_get_error(current, regs)) {
825 case -ERESTARTNOHAND:
826 case -ERESTARTSYS:
827 case -ERESTARTNOINTR:
828 regs->ax = regs->orig_ax;
829 regs->ip -= 2;
830 break;
831
832 case -ERESTART_RESTARTBLOCK:
833 regs->ax = get_nr_restart_syscall(regs);
834 regs->ip -= 2;
835 break;
836 }
837 }
838
839 /*
840 * If there's no signal to deliver, we just put the saved sigmask
841 * back.
842 */
843 restore_saved_sigmask();
844 }
845
signal_fault(struct pt_regs * regs,void __user * frame,char * where)846 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
847 {
848 struct task_struct *me = current;
849
850 if (show_unhandled_signals && printk_ratelimit()) {
851 printk("%s"
852 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
853 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
854 me->comm, me->pid, where, frame,
855 regs->ip, regs->sp, regs->orig_ax);
856 print_vma_addr(KERN_CONT " in ", regs->ip);
857 pr_cont("\n");
858 }
859
860 force_sig(SIGSEGV);
861 }
862
863 #ifdef CONFIG_X86_X32_ABI
sys32_x32_rt_sigreturn(void)864 asmlinkage long sys32_x32_rt_sigreturn(void)
865 {
866 struct pt_regs *regs = current_pt_regs();
867 struct rt_sigframe_x32 __user *frame;
868 sigset_t set;
869 unsigned long uc_flags;
870
871 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
872
873 if (!access_ok(frame, sizeof(*frame)))
874 goto badframe;
875 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
876 goto badframe;
877 if (__get_user(uc_flags, &frame->uc.uc_flags))
878 goto badframe;
879
880 set_current_blocked(&set);
881
882 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
883 goto badframe;
884
885 if (compat_restore_altstack(&frame->uc.uc_stack))
886 goto badframe;
887
888 return regs->ax;
889
890 badframe:
891 signal_fault(regs, frame, "x32 rt_sigreturn");
892 return 0;
893 }
894 #endif
895
