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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/entry-common.h>
29#include <linux/syscalls.h>
30
31#include <asm/processor.h>
32#include <asm/ucontext.h>
33#include <asm/fpu/internal.h>
34#include <asm/fpu/signal.h>
35#include <asm/vdso.h>
36#include <asm/mce.h>
37#include <asm/sighandling.h>
38#include <asm/vm86.h>
39
40#ifdef CONFIG_X86_64
41#include <linux/compat.h>
42#include <asm/proto.h>
43#include <asm/ia32_unistd.h>
44#endif /* CONFIG_X86_64 */
45
46#include <asm/syscall.h>
47#include <asm/sigframe.h>
48#include <asm/signal.h>
49
50#ifdef CONFIG_X86_64
51/*
52 * If regs->ss will cause an IRET fault, change it. Otherwise leave it
53 * alone. Using this generally makes no sense unless
54 * user_64bit_mode(regs) would return true.
55 */
56static void force_valid_ss(struct pt_regs *regs)
57{
58 u32 ar;
59 asm volatile ("lar %[old_ss], %[ar]\n\t"
60 "jz 1f\n\t" /* If invalid: */
61 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */
62 "1:"
63 : [ar] "=r" (ar)
64 : [old_ss] "rm" ((u16)regs->ss));
65
66 /*
67 * For a valid 64-bit user context, we need DPL 3, type
68 * read-write data or read-write exp-down data, and S and P
69 * set. We can't use VERW because VERW doesn't check the
70 * P bit.
71 */
72 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
73 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
74 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
75 regs->ss = __USER_DS;
76}
77# define CONTEXT_COPY_SIZE offsetof(struct sigcontext, reserved1)
78#else
79# define CONTEXT_COPY_SIZE sizeof(struct sigcontext)
80#endif
81
82static int restore_sigcontext(struct pt_regs *regs,
83 struct sigcontext __user *usc,
84 unsigned long uc_flags)
85{
86 struct sigcontext sc;
87
88 /* Always make any pending restarted system calls return -EINTR */
89 current->restart_block.fn = do_no_restart_syscall;
90
91 if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE))
92 return -EFAULT;
93
94#ifdef CONFIG_X86_32
95 set_user_gs(regs, sc.gs);
96 regs->fs = sc.fs;
97 regs->es = sc.es;
98 regs->ds = sc.ds;
99#endif /* CONFIG_X86_32 */
100
101 regs->bx = sc.bx;
102 regs->cx = sc.cx;
103 regs->dx = sc.dx;
104 regs->si = sc.si;
105 regs->di = sc.di;
106 regs->bp = sc.bp;
107 regs->ax = sc.ax;
108 regs->sp = sc.sp;
109 regs->ip = sc.ip;
110
111#ifdef CONFIG_X86_64
112 regs->r8 = sc.r8;
113 regs->r9 = sc.r9;
114 regs->r10 = sc.r10;
115 regs->r11 = sc.r11;
116 regs->r12 = sc.r12;
117 regs->r13 = sc.r13;
118 regs->r14 = sc.r14;
119 regs->r15 = sc.r15;
120#endif /* CONFIG_X86_64 */
121
122 /* Get CS/SS and force CPL3 */
123 regs->cs = sc.cs | 0x03;
124 regs->ss = sc.ss | 0x03;
125
126 regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
127 /* disable syscall checks */
128 regs->orig_ax = -1;
129
130#ifdef CONFIG_X86_64
131 /*
132 * Fix up SS if needed for the benefit of old DOSEMU and
133 * CRIU.
134 */
135 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
136 force_valid_ss(regs);
137#endif
138
139 return fpu__restore_sig((void __user *)sc.fpstate,
140 IS_ENABLED(CONFIG_X86_32));
141}
142
143static __always_inline int
144__unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
145 struct pt_regs *regs, unsigned long mask)
146{
147#ifdef CONFIG_X86_32
148 unsafe_put_user(get_user_gs(regs),
149 (unsigned int __user *)&sc->gs, Efault);
150 unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
151 unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
152 unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
153#endif /* CONFIG_X86_32 */
154
155 unsafe_put_user(regs->di, &sc->di, Efault);
156 unsafe_put_user(regs->si, &sc->si, Efault);
157 unsafe_put_user(regs->bp, &sc->bp, Efault);
158 unsafe_put_user(regs->sp, &sc->sp, Efault);
159 unsafe_put_user(regs->bx, &sc->bx, Efault);
160 unsafe_put_user(regs->dx, &sc->dx, Efault);
161 unsafe_put_user(regs->cx, &sc->cx, Efault);
162 unsafe_put_user(regs->ax, &sc->ax, Efault);
163#ifdef CONFIG_X86_64
164 unsafe_put_user(regs->r8, &sc->r8, Efault);
165 unsafe_put_user(regs->r9, &sc->r9, Efault);
166 unsafe_put_user(regs->r10, &sc->r10, Efault);
167 unsafe_put_user(regs->r11, &sc->r11, Efault);
168 unsafe_put_user(regs->r12, &sc->r12, Efault);
169 unsafe_put_user(regs->r13, &sc->r13, Efault);
170 unsafe_put_user(regs->r14, &sc->r14, Efault);
171 unsafe_put_user(regs->r15, &sc->r15, Efault);
172#endif /* CONFIG_X86_64 */
173
174 unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
175 unsafe_put_user(current->thread.error_code, &sc->err, Efault);
176 unsafe_put_user(regs->ip, &sc->ip, Efault);
177#ifdef CONFIG_X86_32
178 unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
179 unsafe_put_user(regs->flags, &sc->flags, Efault);
180 unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
181 unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
182#else /* !CONFIG_X86_32 */
183 unsafe_put_user(regs->flags, &sc->flags, Efault);
184 unsafe_put_user(regs->cs, &sc->cs, Efault);
185 unsafe_put_user(0, &sc->gs, Efault);
186 unsafe_put_user(0, &sc->fs, Efault);
187 unsafe_put_user(regs->ss, &sc->ss, Efault);
188#endif /* CONFIG_X86_32 */
189
190 unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault);
191
192 /* non-iBCS2 extensions.. */
193 unsafe_put_user(mask, &sc->oldmask, Efault);
194 unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
195 return 0;
196Efault:
197 return -EFAULT;
198}
199
200#define unsafe_put_sigcontext(sc, fp, regs, set, label) \
201do { \
202 if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \
203 goto label; \
204} while(0);
205
206#define unsafe_put_sigmask(set, frame, label) \
207 unsafe_put_user(*(__u64 *)(set), \
208 (__u64 __user *)&(frame)->uc.uc_sigmask, \
209 label)
210
211/*
212 * Set up a signal frame.
213 */
214
215/* x86 ABI requires 16-byte alignment */
216#define FRAME_ALIGNMENT 16UL
217
218#define MAX_FRAME_PADDING (FRAME_ALIGNMENT - 1)
219
220/*
221 * Determine which stack to use..
222 */
223static unsigned long align_sigframe(unsigned long sp)
224{
225#ifdef CONFIG_X86_32
226 /*
227 * Align the stack pointer according to the i386 ABI,
228 * i.e. so that on function entry ((sp + 4) & 15) == 0.
229 */
230 sp = ((sp + 4) & -FRAME_ALIGNMENT) - 4;
231#else /* !CONFIG_X86_32 */
232 sp = round_down(sp, FRAME_ALIGNMENT) - 8;
233#endif
234 return sp;
235}
236
237static void __user *
238get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
239 void __user **fpstate)
240{
241 /* Default to using normal stack */
242 bool nested_altstack = on_sig_stack(regs->sp);
243 bool entering_altstack = false;
244 unsigned long math_size = 0;
245 unsigned long sp = regs->sp;
246 unsigned long buf_fx = 0;
247 int ret;
248
249 /* redzone */
250 if (IS_ENABLED(CONFIG_X86_64))
251 sp -= 128;
252
253 /* This is the X/Open sanctioned signal stack switching. */
254 if (ka->sa.sa_flags & SA_ONSTACK) {
255 /*
256 * This checks nested_altstack via sas_ss_flags(). Sensible
257 * programs use SS_AUTODISARM, which disables that check, and
258 * programs that don't use SS_AUTODISARM get compatible.
259 */
260 if (sas_ss_flags(sp) == 0) {
261 sp = current->sas_ss_sp + current->sas_ss_size;
262 entering_altstack = true;
263 }
264 } else if (IS_ENABLED(CONFIG_X86_32) &&
265 !nested_altstack &&
266 regs->ss != __USER_DS &&
267 !(ka->sa.sa_flags & SA_RESTORER) &&
268 ka->sa.sa_restorer) {
269 /* This is the legacy signal stack switching. */
270 sp = (unsigned long) ka->sa.sa_restorer;
271 entering_altstack = true;
272 }
273
274 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
275 &buf_fx, &math_size);
276 *fpstate = (void __user *)sp;
277
278 sp = align_sigframe(sp - frame_size);
279
280 /*
281 * If we are on the alternate signal stack and would overflow it, don't.
282 * Return an always-bogus address instead so we will die with SIGSEGV.
283 */
284 if (unlikely((nested_altstack || entering_altstack) &&
285 !__on_sig_stack(sp))) {
286
287 if (show_unhandled_signals && printk_ratelimit())
288 pr_info("%s[%d] overflowed sigaltstack\n",
289 current->comm, task_pid_nr(current));
290
291 return (void __user *)-1L;
292 }
293
294 /* save i387 and extended state */
295 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size);
296 if (ret < 0)
297 return (void __user *)-1L;
298
299 return (void __user *)sp;
300}
301
302#ifdef CONFIG_X86_32
303static const struct {
304 u16 poplmovl;
305 u32 val;
306 u16 int80;
307} __attribute__((packed)) retcode = {
308 0xb858, /* popl %eax; movl $..., %eax */
309 __NR_sigreturn,
310 0x80cd, /* int $0x80 */
311};
312
313static const struct {
314 u8 movl;
315 u32 val;
316 u16 int80;
317 u8 pad;
318} __attribute__((packed)) rt_retcode = {
319 0xb8, /* movl $..., %eax */
320 __NR_rt_sigreturn,
321 0x80cd, /* int $0x80 */
322 0
323};
324
325static int
326__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
327 struct pt_regs *regs)
328{
329 struct sigframe __user *frame;
330 void __user *restorer;
331 void __user *fp = NULL;
332
333 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
334
335 if (!user_access_begin(frame, sizeof(*frame)))
336 return -EFAULT;
337
338 unsafe_put_user(sig, &frame->sig, Efault);
339 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault);
340 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
341 if (current->mm->context.vdso)
342 restorer = current->mm->context.vdso +
343 vdso_image_32.sym___kernel_sigreturn;
344 else
345 restorer = &frame->retcode;
346 if (ksig->ka.sa.sa_flags & SA_RESTORER)
347 restorer = ksig->ka.sa.sa_restorer;
348
349 /* Set up to return from userspace. */
350 unsafe_put_user(restorer, &frame->pretcode, Efault);
351
352 /*
353 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
354 *
355 * WE DO NOT USE IT ANY MORE! It's only left here for historical
356 * reasons and because gdb uses it as a signature to notice
357 * signal handler stack frames.
358 */
359 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
360 user_access_end();
361
362 /* Set up registers for signal handler */
363 regs->sp = (unsigned long)frame;
364 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
365 regs->ax = (unsigned long)sig;
366 regs->dx = 0;
367 regs->cx = 0;
368
369 regs->ds = __USER_DS;
370 regs->es = __USER_DS;
371 regs->ss = __USER_DS;
372 regs->cs = __USER_CS;
373
374 return 0;
375
376Efault:
377 user_access_end();
378 return -EFAULT;
379}
380
381static int __setup_rt_frame(int sig, struct ksignal *ksig,
382 sigset_t *set, struct pt_regs *regs)
383{
384 struct rt_sigframe __user *frame;
385 void __user *restorer;
386 void __user *fp = NULL;
387
388 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
389
390 if (!user_access_begin(frame, sizeof(*frame)))
391 return -EFAULT;
392
393 unsafe_put_user(sig, &frame->sig, Efault);
394 unsafe_put_user(&frame->info, &frame->pinfo, Efault);
395 unsafe_put_user(&frame->uc, &frame->puc, Efault);
396
397 /* Create the ucontext. */
398 if (static_cpu_has(X86_FEATURE_XSAVE))
399 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
400 else
401 unsafe_put_user(0, &frame->uc.uc_flags, Efault);
402 unsafe_put_user(0, &frame->uc.uc_link, Efault);
403 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
404
405 /* Set up to return from userspace. */
406 restorer = current->mm->context.vdso +
407 vdso_image_32.sym___kernel_rt_sigreturn;
408 if (ksig->ka.sa.sa_flags & SA_RESTORER)
409 restorer = ksig->ka.sa.sa_restorer;
410 unsafe_put_user(restorer, &frame->pretcode, Efault);
411
412 /*
413 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
414 *
415 * WE DO NOT USE IT ANY MORE! It's only left here for historical
416 * reasons and because gdb uses it as a signature to notice
417 * signal handler stack frames.
418 */
419 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
420 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
421 unsafe_put_sigmask(set, frame, Efault);
422 user_access_end();
423
424 if (copy_siginfo_to_user(&frame->info, &ksig->info))
425 return -EFAULT;
426
427 /* Set up registers for signal handler */
428 regs->sp = (unsigned long)frame;
429 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
430 regs->ax = (unsigned long)sig;
431 regs->dx = (unsigned long)&frame->info;
432 regs->cx = (unsigned long)&frame->uc;
433
434 regs->ds = __USER_DS;
435 regs->es = __USER_DS;
436 regs->ss = __USER_DS;
437 regs->cs = __USER_CS;
438
439 return 0;
440Efault:
441 user_access_end();
442 return -EFAULT;
443}
444#else /* !CONFIG_X86_32 */
445static unsigned long frame_uc_flags(struct pt_regs *regs)
446{
447 unsigned long flags;
448
449 if (boot_cpu_has(X86_FEATURE_XSAVE))
450 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
451 else
452 flags = UC_SIGCONTEXT_SS;
453
454 if (likely(user_64bit_mode(regs)))
455 flags |= UC_STRICT_RESTORE_SS;
456
457 return flags;
458}
459
460static int __setup_rt_frame(int sig, struct ksignal *ksig,
461 sigset_t *set, struct pt_regs *regs)
462{
463 struct rt_sigframe __user *frame;
464 void __user *fp = NULL;
465 unsigned long uc_flags;
466
467 /* x86-64 should always use SA_RESTORER. */
468 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
469 return -EFAULT;
470
471 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
472 uc_flags = frame_uc_flags(regs);
473
474 if (!user_access_begin(frame, sizeof(*frame)))
475 return -EFAULT;
476
477 /* Create the ucontext. */
478 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
479 unsafe_put_user(0, &frame->uc.uc_link, Efault);
480 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
481
482 /* Set up to return from userspace. If provided, use a stub
483 already in userspace. */
484 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
485 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
486 unsafe_put_sigmask(set, frame, Efault);
487 user_access_end();
488
489 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
490 if (copy_siginfo_to_user(&frame->info, &ksig->info))
491 return -EFAULT;
492 }
493
494 /* Set up registers for signal handler */
495 regs->di = sig;
496 /* In case the signal handler was declared without prototypes */
497 regs->ax = 0;
498
499 /* This also works for non SA_SIGINFO handlers because they expect the
500 next argument after the signal number on the stack. */
501 regs->si = (unsigned long)&frame->info;
502 regs->dx = (unsigned long)&frame->uc;
503 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
504
505 regs->sp = (unsigned long)frame;
506
507 /*
508 * Set up the CS and SS registers to run signal handlers in
509 * 64-bit mode, even if the handler happens to be interrupting
510 * 32-bit or 16-bit code.
511 *
512 * SS is subtle. In 64-bit mode, we don't need any particular
513 * SS descriptor, but we do need SS to be valid. It's possible
514 * that the old SS is entirely bogus -- this can happen if the
515 * signal we're trying to deliver is #GP or #SS caused by a bad
516 * SS value. We also have a compatibility issue here: DOSEMU
517 * relies on the contents of the SS register indicating the
518 * SS value at the time of the signal, even though that code in
519 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
520 * avoids relying on sigreturn to restore SS; instead it uses
521 * a trampoline.) So we do our best: if the old SS was valid,
522 * we keep it. Otherwise we replace it.
523 */
524 regs->cs = __USER_CS;
525
526 if (unlikely(regs->ss != __USER_DS))
527 force_valid_ss(regs);
528
529 return 0;
530
531Efault:
532 user_access_end();
533 return -EFAULT;
534}
535#endif /* CONFIG_X86_32 */
536
537#ifdef CONFIG_X86_X32_ABI
538static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
539 const struct kernel_siginfo *from)
540{
541 struct compat_siginfo new;
542
543 copy_siginfo_to_external32(&new, from);
544 if (from->si_signo == SIGCHLD) {
545 new._sifields._sigchld_x32._utime = from->si_utime;
546 new._sifields._sigchld_x32._stime = from->si_stime;
547 }
548 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
549 return -EFAULT;
550 return 0;
551}
552
553int copy_siginfo_to_user32(struct compat_siginfo __user *to,
554 const struct kernel_siginfo *from)
555{
556 if (in_x32_syscall())
557 return x32_copy_siginfo_to_user(to, from);
558 return __copy_siginfo_to_user32(to, from);
559}
560#endif /* CONFIG_X86_X32_ABI */
561
562static int x32_setup_rt_frame(struct ksignal *ksig,
563 compat_sigset_t *set,
564 struct pt_regs *regs)
565{
566#ifdef CONFIG_X86_X32_ABI
567 struct rt_sigframe_x32 __user *frame;
568 unsigned long uc_flags;
569 void __user *restorer;
570 void __user *fp = NULL;
571
572 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
573 return -EFAULT;
574
575 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
576
577 uc_flags = frame_uc_flags(regs);
578
579 if (!user_access_begin(frame, sizeof(*frame)))
580 return -EFAULT;
581
582 /* Create the ucontext. */
583 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
584 unsafe_put_user(0, &frame->uc.uc_link, Efault);
585 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
586 unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
587 restorer = ksig->ka.sa.sa_restorer;
588 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
589 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
590 unsafe_put_sigmask(set, frame, Efault);
591 user_access_end();
592
593 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
594 if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
595 return -EFAULT;
596 }
597
598 /* Set up registers for signal handler */
599 regs->sp = (unsigned long) frame;
600 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
601
602 /* We use the x32 calling convention here... */
603 regs->di = ksig->sig;
604 regs->si = (unsigned long) &frame->info;
605 regs->dx = (unsigned long) &frame->uc;
606
607 loadsegment(ds, __USER_DS);
608 loadsegment(es, __USER_DS);
609
610 regs->cs = __USER_CS;
611 regs->ss = __USER_DS;
612#endif /* CONFIG_X86_X32_ABI */
613
614 return 0;
615#ifdef CONFIG_X86_X32_ABI
616Efault:
617 user_access_end();
618 return -EFAULT;
619#endif
620}
621
622/*
623 * Do a signal return; undo the signal stack.
624 */
625#ifdef CONFIG_X86_32
626SYSCALL_DEFINE0(sigreturn)
627{
628 struct pt_regs *regs = current_pt_regs();
629 struct sigframe __user *frame;
630 sigset_t set;
631
632 frame = (struct sigframe __user *)(regs->sp - 8);
633
634 if (!access_ok(frame, sizeof(*frame)))
635 goto badframe;
636 if (__get_user(set.sig[0], &frame->sc.oldmask) ||
637 __get_user(set.sig[1], &frame->extramask[0]))
638 goto badframe;
639
640 set_current_blocked(&set);
641
642 /*
643 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
644 * Save a few cycles by skipping the __get_user.
645 */
646 if (restore_sigcontext(regs, &frame->sc, 0))
647 goto badframe;
648 return regs->ax;
649
650badframe:
651 signal_fault(regs, frame, "sigreturn");
652
653 return 0;
654}
655#endif /* CONFIG_X86_32 */
656
657SYSCALL_DEFINE0(rt_sigreturn)
658{
659 struct pt_regs *regs = current_pt_regs();
660 struct rt_sigframe __user *frame;
661 sigset_t set;
662 unsigned long uc_flags;
663
664 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
665 if (!access_ok(frame, sizeof(*frame)))
666 goto badframe;
667 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
668 goto badframe;
669 if (__get_user(uc_flags, &frame->uc.uc_flags))
670 goto badframe;
671
672 set_current_blocked(&set);
673
674 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
675 goto badframe;
676
677 if (restore_altstack(&frame->uc.uc_stack))
678 goto badframe;
679
680 return regs->ax;
681
682badframe:
683 signal_fault(regs, frame, "rt_sigreturn");
684 return 0;
685}
686
687/*
688 * There are four different struct types for signal frame: sigframe_ia32,
689 * rt_sigframe_ia32, rt_sigframe_x32, and rt_sigframe. Use the worst case
690 * -- the largest size. It means the size for 64-bit apps is a bit more
691 * than needed, but this keeps the code simple.
692 */
693#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
694# define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct sigframe_ia32)
695#else
696# define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct rt_sigframe)
697#endif
698
699/*
700 * The FP state frame contains an XSAVE buffer which must be 64-byte aligned.
701 * If a signal frame starts at an unaligned address, extra space is required.
702 * This is the max alignment padding, conservatively.
703 */
704#define MAX_XSAVE_PADDING 63UL
705
706/*
707 * The frame data is composed of the following areas and laid out as:
708 *
709 * -------------------------
710 * | alignment padding |
711 * -------------------------
712 * | (f)xsave frame |
713 * -------------------------
714 * | fsave header |
715 * -------------------------
716 * | alignment padding |
717 * -------------------------
718 * | siginfo + ucontext |
719 * -------------------------
720 */
721
722/* max_frame_size tells userspace the worst case signal stack size. */
723static unsigned long __ro_after_init max_frame_size;
724
725void __init init_sigframe_size(void)
726{
727 max_frame_size = MAX_FRAME_SIGINFO_UCTXT_SIZE + MAX_FRAME_PADDING;
728
729 max_frame_size += fpu__get_fpstate_size() + MAX_XSAVE_PADDING;
730
731 /* Userspace expects an aligned size. */
732 max_frame_size = round_up(max_frame_size, FRAME_ALIGNMENT);
733
734 pr_info("max sigframe size: %lu\n", max_frame_size);
735}
736
737unsigned long get_sigframe_size(void)
738{
739 return max_frame_size;
740}
741
742static inline int is_ia32_compat_frame(struct ksignal *ksig)
743{
744 return IS_ENABLED(CONFIG_IA32_EMULATION) &&
745 ksig->ka.sa.sa_flags & SA_IA32_ABI;
746}
747
748static inline int is_ia32_frame(struct ksignal *ksig)
749{
750 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
751}
752
753static inline int is_x32_frame(struct ksignal *ksig)
754{
755 return IS_ENABLED(CONFIG_X86_X32_ABI) &&
756 ksig->ka.sa.sa_flags & SA_X32_ABI;
757}
758
759static int
760setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
761{
762 int usig = ksig->sig;
763 sigset_t *set = sigmask_to_save();
764 compat_sigset_t *cset = (compat_sigset_t *) set;
765
766 /* Perform fixup for the pre-signal frame. */
767 rseq_signal_deliver(ksig, regs);
768
769 /* Set up the stack frame */
770 if (is_ia32_frame(ksig)) {
771 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
772 return ia32_setup_rt_frame(usig, ksig, cset, regs);
773 else
774 return ia32_setup_frame(usig, ksig, cset, regs);
775 } else if (is_x32_frame(ksig)) {
776 return x32_setup_rt_frame(ksig, cset, regs);
777 } else {
778 return __setup_rt_frame(ksig->sig, ksig, set, regs);
779 }
780}
781
782static void
783handle_signal(struct ksignal *ksig, struct pt_regs *regs)
784{
785 bool stepping, failed;
786 struct fpu *fpu = ¤t->thread.fpu;
787
788 if (v8086_mode(regs))
789 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
790
791 /* Are we from a system call? */
792 if (syscall_get_nr(current, regs) != -1) {
793 /* If so, check system call restarting.. */
794 switch (syscall_get_error(current, regs)) {
795 case -ERESTART_RESTARTBLOCK:
796 case -ERESTARTNOHAND:
797 regs->ax = -EINTR;
798 break;
799
800 case -ERESTARTSYS:
801 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
802 regs->ax = -EINTR;
803 break;
804 }
805 fallthrough;
806 case -ERESTARTNOINTR:
807 regs->ax = regs->orig_ax;
808 regs->ip -= 2;
809 break;
810 }
811 }
812
813 /*
814 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
815 * so that register information in the sigcontext is correct and
816 * then notify the tracer before entering the signal handler.
817 */
818 stepping = test_thread_flag(TIF_SINGLESTEP);
819 if (stepping)
820 user_disable_single_step(current);
821
822 failed = (setup_rt_frame(ksig, regs) < 0);
823 if (!failed) {
824 /*
825 * Clear the direction flag as per the ABI for function entry.
826 *
827 * Clear RF when entering the signal handler, because
828 * it might disable possible debug exception from the
829 * signal handler.
830 *
831 * Clear TF for the case when it wasn't set by debugger to
832 * avoid the recursive send_sigtrap() in SIGTRAP handler.
833 */
834 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
835 /*
836 * Ensure the signal handler starts with the new fpu state.
837 */
838 fpu__clear_user_states(fpu);
839 }
840 signal_setup_done(failed, ksig, stepping);
841}
842
843static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
844{
845#ifdef CONFIG_IA32_EMULATION
846 if (current->restart_block.arch_data & TS_COMPAT)
847 return __NR_ia32_restart_syscall;
848#endif
849#ifdef CONFIG_X86_X32_ABI
850 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
851#else
852 return __NR_restart_syscall;
853#endif
854}
855
856/*
857 * Note that 'init' is a special process: it doesn't get signals it doesn't
858 * want to handle. Thus you cannot kill init even with a SIGKILL even by
859 * mistake.
860 */
861void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
862{
863 struct ksignal ksig;
864
865 if (has_signal && get_signal(&ksig)) {
866 /* Whee! Actually deliver the signal. */
867 handle_signal(&ksig, regs);
868 return;
869 }
870
871 /* Did we come from a system call? */
872 if (syscall_get_nr(current, regs) != -1) {
873 /* Restart the system call - no handlers present */
874 switch (syscall_get_error(current, regs)) {
875 case -ERESTARTNOHAND:
876 case -ERESTARTSYS:
877 case -ERESTARTNOINTR:
878 regs->ax = regs->orig_ax;
879 regs->ip -= 2;
880 break;
881
882 case -ERESTART_RESTARTBLOCK:
883 regs->ax = get_nr_restart_syscall(regs);
884 regs->ip -= 2;
885 break;
886 }
887 }
888
889 /*
890 * If there's no signal to deliver, we just put the saved sigmask
891 * back.
892 */
893 restore_saved_sigmask();
894}
895
896void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
897{
898 struct task_struct *me = current;
899
900 if (show_unhandled_signals && printk_ratelimit()) {
901 printk("%s"
902 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
903 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
904 me->comm, me->pid, where, frame,
905 regs->ip, regs->sp, regs->orig_ax);
906 print_vma_addr(KERN_CONT " in ", regs->ip);
907 pr_cont("\n");
908 }
909
910 force_sig(SIGSEGV);
911}
912
913#ifdef CONFIG_X86_X32_ABI
914COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
915{
916 struct pt_regs *regs = current_pt_regs();
917 struct rt_sigframe_x32 __user *frame;
918 sigset_t set;
919 unsigned long uc_flags;
920
921 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
922
923 if (!access_ok(frame, sizeof(*frame)))
924 goto badframe;
925 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
926 goto badframe;
927 if (__get_user(uc_flags, &frame->uc.uc_flags))
928 goto badframe;
929
930 set_current_blocked(&set);
931
932 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
933 goto badframe;
934
935 if (compat_restore_altstack(&frame->uc.uc_stack))
936 goto badframe;
937
938 return regs->ax;
939
940badframe:
941 signal_fault(regs, frame, "x32 rt_sigreturn");
942 return 0;
943}
944#endif
1/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
4 *
5 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
6 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
7 * 2000-2002 x86-64 support by Andi Kleen
8 */
9#include <linux/sched.h>
10#include <linux/mm.h>
11#include <linux/smp.h>
12#include <linux/kernel.h>
13#include <linux/signal.h>
14#include <linux/errno.h>
15#include <linux/wait.h>
16#include <linux/ptrace.h>
17#include <linux/tracehook.h>
18#include <linux/unistd.h>
19#include <linux/stddef.h>
20#include <linux/personality.h>
21#include <linux/uaccess.h>
22#include <linux/user-return-notifier.h>
23
24#include <asm/processor.h>
25#include <asm/ucontext.h>
26#include <asm/i387.h>
27#include <asm/vdso.h>
28#include <asm/mce.h>
29
30#ifdef CONFIG_X86_64
31#include <asm/proto.h>
32#include <asm/ia32_unistd.h>
33#endif /* CONFIG_X86_64 */
34
35#include <asm/syscall.h>
36#include <asm/syscalls.h>
37
38#include <asm/sigframe.h>
39
40#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
41
42#define __FIX_EFLAGS (X86_EFLAGS_AC | X86_EFLAGS_OF | \
43 X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
44 X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
45 X86_EFLAGS_CF)
46
47#ifdef CONFIG_X86_32
48# define FIX_EFLAGS (__FIX_EFLAGS | X86_EFLAGS_RF)
49#else
50# define FIX_EFLAGS __FIX_EFLAGS
51#endif
52
53#define COPY(x) do { \
54 get_user_ex(regs->x, &sc->x); \
55} while (0)
56
57#define GET_SEG(seg) ({ \
58 unsigned short tmp; \
59 get_user_ex(tmp, &sc->seg); \
60 tmp; \
61})
62
63#define COPY_SEG(seg) do { \
64 regs->seg = GET_SEG(seg); \
65} while (0)
66
67#define COPY_SEG_CPL3(seg) do { \
68 regs->seg = GET_SEG(seg) | 3; \
69} while (0)
70
71static int
72restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
73 unsigned long *pax)
74{
75 void __user *buf;
76 unsigned int tmpflags;
77 unsigned int err = 0;
78
79 /* Always make any pending restarted system calls return -EINTR */
80 current_thread_info()->restart_block.fn = do_no_restart_syscall;
81
82 get_user_try {
83
84#ifdef CONFIG_X86_32
85 set_user_gs(regs, GET_SEG(gs));
86 COPY_SEG(fs);
87 COPY_SEG(es);
88 COPY_SEG(ds);
89#endif /* CONFIG_X86_32 */
90
91 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
92 COPY(dx); COPY(cx); COPY(ip);
93
94#ifdef CONFIG_X86_64
95 COPY(r8);
96 COPY(r9);
97 COPY(r10);
98 COPY(r11);
99 COPY(r12);
100 COPY(r13);
101 COPY(r14);
102 COPY(r15);
103#endif /* CONFIG_X86_64 */
104
105#ifdef CONFIG_X86_32
106 COPY_SEG_CPL3(cs);
107 COPY_SEG_CPL3(ss);
108#else /* !CONFIG_X86_32 */
109 /* Kernel saves and restores only the CS segment register on signals,
110 * which is the bare minimum needed to allow mixed 32/64-bit code.
111 * App's signal handler can save/restore other segments if needed. */
112 COPY_SEG_CPL3(cs);
113#endif /* CONFIG_X86_32 */
114
115 get_user_ex(tmpflags, &sc->flags);
116 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
117 regs->orig_ax = -1; /* disable syscall checks */
118
119 get_user_ex(buf, &sc->fpstate);
120 err |= restore_i387_xstate(buf);
121
122 get_user_ex(*pax, &sc->ax);
123 } get_user_catch(err);
124
125 return err;
126}
127
128static int
129setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
130 struct pt_regs *regs, unsigned long mask)
131{
132 int err = 0;
133
134 put_user_try {
135
136#ifdef CONFIG_X86_32
137 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
138 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
139 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
140 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
141#endif /* CONFIG_X86_32 */
142
143 put_user_ex(regs->di, &sc->di);
144 put_user_ex(regs->si, &sc->si);
145 put_user_ex(regs->bp, &sc->bp);
146 put_user_ex(regs->sp, &sc->sp);
147 put_user_ex(regs->bx, &sc->bx);
148 put_user_ex(regs->dx, &sc->dx);
149 put_user_ex(regs->cx, &sc->cx);
150 put_user_ex(regs->ax, &sc->ax);
151#ifdef CONFIG_X86_64
152 put_user_ex(regs->r8, &sc->r8);
153 put_user_ex(regs->r9, &sc->r9);
154 put_user_ex(regs->r10, &sc->r10);
155 put_user_ex(regs->r11, &sc->r11);
156 put_user_ex(regs->r12, &sc->r12);
157 put_user_ex(regs->r13, &sc->r13);
158 put_user_ex(regs->r14, &sc->r14);
159 put_user_ex(regs->r15, &sc->r15);
160#endif /* CONFIG_X86_64 */
161
162 put_user_ex(current->thread.trap_no, &sc->trapno);
163 put_user_ex(current->thread.error_code, &sc->err);
164 put_user_ex(regs->ip, &sc->ip);
165#ifdef CONFIG_X86_32
166 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
167 put_user_ex(regs->flags, &sc->flags);
168 put_user_ex(regs->sp, &sc->sp_at_signal);
169 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
170#else /* !CONFIG_X86_32 */
171 put_user_ex(regs->flags, &sc->flags);
172 put_user_ex(regs->cs, &sc->cs);
173 put_user_ex(0, &sc->gs);
174 put_user_ex(0, &sc->fs);
175#endif /* CONFIG_X86_32 */
176
177 put_user_ex(fpstate, &sc->fpstate);
178
179 /* non-iBCS2 extensions.. */
180 put_user_ex(mask, &sc->oldmask);
181 put_user_ex(current->thread.cr2, &sc->cr2);
182 } put_user_catch(err);
183
184 return err;
185}
186
187/*
188 * Set up a signal frame.
189 */
190
191/*
192 * Determine which stack to use..
193 */
194static unsigned long align_sigframe(unsigned long sp)
195{
196#ifdef CONFIG_X86_32
197 /*
198 * Align the stack pointer according to the i386 ABI,
199 * i.e. so that on function entry ((sp + 4) & 15) == 0.
200 */
201 sp = ((sp + 4) & -16ul) - 4;
202#else /* !CONFIG_X86_32 */
203 sp = round_down(sp, 16) - 8;
204#endif
205 return sp;
206}
207
208static inline void __user *
209get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
210 void __user **fpstate)
211{
212 /* Default to using normal stack */
213 unsigned long sp = regs->sp;
214 int onsigstack = on_sig_stack(sp);
215
216#ifdef CONFIG_X86_64
217 /* redzone */
218 sp -= 128;
219#endif /* CONFIG_X86_64 */
220
221 if (!onsigstack) {
222 /* This is the X/Open sanctioned signal stack switching. */
223 if (ka->sa.sa_flags & SA_ONSTACK) {
224 if (current->sas_ss_size)
225 sp = current->sas_ss_sp + current->sas_ss_size;
226 } else {
227#ifdef CONFIG_X86_32
228 /* This is the legacy signal stack switching. */
229 if ((regs->ss & 0xffff) != __USER_DS &&
230 !(ka->sa.sa_flags & SA_RESTORER) &&
231 ka->sa.sa_restorer)
232 sp = (unsigned long) ka->sa.sa_restorer;
233#endif /* CONFIG_X86_32 */
234 }
235 }
236
237 if (used_math()) {
238 sp -= sig_xstate_size;
239#ifdef CONFIG_X86_64
240 sp = round_down(sp, 64);
241#endif /* CONFIG_X86_64 */
242 *fpstate = (void __user *)sp;
243 }
244
245 sp = align_sigframe(sp - frame_size);
246
247 /*
248 * If we are on the alternate signal stack and would overflow it, don't.
249 * Return an always-bogus address instead so we will die with SIGSEGV.
250 */
251 if (onsigstack && !likely(on_sig_stack(sp)))
252 return (void __user *)-1L;
253
254 /* save i387 state */
255 if (used_math() && save_i387_xstate(*fpstate) < 0)
256 return (void __user *)-1L;
257
258 return (void __user *)sp;
259}
260
261#ifdef CONFIG_X86_32
262static const struct {
263 u16 poplmovl;
264 u32 val;
265 u16 int80;
266} __attribute__((packed)) retcode = {
267 0xb858, /* popl %eax; movl $..., %eax */
268 __NR_sigreturn,
269 0x80cd, /* int $0x80 */
270};
271
272static const struct {
273 u8 movl;
274 u32 val;
275 u16 int80;
276 u8 pad;
277} __attribute__((packed)) rt_retcode = {
278 0xb8, /* movl $..., %eax */
279 __NR_rt_sigreturn,
280 0x80cd, /* int $0x80 */
281 0
282};
283
284static int
285__setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
286 struct pt_regs *regs)
287{
288 struct sigframe __user *frame;
289 void __user *restorer;
290 int err = 0;
291 void __user *fpstate = NULL;
292
293 frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
294
295 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
296 return -EFAULT;
297
298 if (__put_user(sig, &frame->sig))
299 return -EFAULT;
300
301 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
302 return -EFAULT;
303
304 if (_NSIG_WORDS > 1) {
305 if (__copy_to_user(&frame->extramask, &set->sig[1],
306 sizeof(frame->extramask)))
307 return -EFAULT;
308 }
309
310 if (current->mm->context.vdso)
311 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
312 else
313 restorer = &frame->retcode;
314 if (ka->sa.sa_flags & SA_RESTORER)
315 restorer = ka->sa.sa_restorer;
316
317 /* Set up to return from userspace. */
318 err |= __put_user(restorer, &frame->pretcode);
319
320 /*
321 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
322 *
323 * WE DO NOT USE IT ANY MORE! It's only left here for historical
324 * reasons and because gdb uses it as a signature to notice
325 * signal handler stack frames.
326 */
327 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
328
329 if (err)
330 return -EFAULT;
331
332 /* Set up registers for signal handler */
333 regs->sp = (unsigned long)frame;
334 regs->ip = (unsigned long)ka->sa.sa_handler;
335 regs->ax = (unsigned long)sig;
336 regs->dx = 0;
337 regs->cx = 0;
338
339 regs->ds = __USER_DS;
340 regs->es = __USER_DS;
341 regs->ss = __USER_DS;
342 regs->cs = __USER_CS;
343
344 return 0;
345}
346
347static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
348 sigset_t *set, struct pt_regs *regs)
349{
350 struct rt_sigframe __user *frame;
351 void __user *restorer;
352 int err = 0;
353 void __user *fpstate = NULL;
354
355 frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
356
357 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
358 return -EFAULT;
359
360 put_user_try {
361 put_user_ex(sig, &frame->sig);
362 put_user_ex(&frame->info, &frame->pinfo);
363 put_user_ex(&frame->uc, &frame->puc);
364 err |= copy_siginfo_to_user(&frame->info, info);
365
366 /* Create the ucontext. */
367 if (cpu_has_xsave)
368 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
369 else
370 put_user_ex(0, &frame->uc.uc_flags);
371 put_user_ex(0, &frame->uc.uc_link);
372 put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
373 put_user_ex(sas_ss_flags(regs->sp),
374 &frame->uc.uc_stack.ss_flags);
375 put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
376 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
377 regs, set->sig[0]);
378 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
379
380 /* Set up to return from userspace. */
381 restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
382 if (ka->sa.sa_flags & SA_RESTORER)
383 restorer = ka->sa.sa_restorer;
384 put_user_ex(restorer, &frame->pretcode);
385
386 /*
387 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
388 *
389 * WE DO NOT USE IT ANY MORE! It's only left here for historical
390 * reasons and because gdb uses it as a signature to notice
391 * signal handler stack frames.
392 */
393 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
394 } put_user_catch(err);
395
396 if (err)
397 return -EFAULT;
398
399 /* Set up registers for signal handler */
400 regs->sp = (unsigned long)frame;
401 regs->ip = (unsigned long)ka->sa.sa_handler;
402 regs->ax = (unsigned long)sig;
403 regs->dx = (unsigned long)&frame->info;
404 regs->cx = (unsigned long)&frame->uc;
405
406 regs->ds = __USER_DS;
407 regs->es = __USER_DS;
408 regs->ss = __USER_DS;
409 regs->cs = __USER_CS;
410
411 return 0;
412}
413#else /* !CONFIG_X86_32 */
414static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
415 sigset_t *set, struct pt_regs *regs)
416{
417 struct rt_sigframe __user *frame;
418 void __user *fp = NULL;
419 int err = 0;
420 struct task_struct *me = current;
421
422 frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe), &fp);
423
424 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
425 return -EFAULT;
426
427 if (ka->sa.sa_flags & SA_SIGINFO) {
428 if (copy_siginfo_to_user(&frame->info, info))
429 return -EFAULT;
430 }
431
432 put_user_try {
433 /* Create the ucontext. */
434 if (cpu_has_xsave)
435 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
436 else
437 put_user_ex(0, &frame->uc.uc_flags);
438 put_user_ex(0, &frame->uc.uc_link);
439 put_user_ex(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
440 put_user_ex(sas_ss_flags(regs->sp),
441 &frame->uc.uc_stack.ss_flags);
442 put_user_ex(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
443 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
444 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
445
446 /* Set up to return from userspace. If provided, use a stub
447 already in userspace. */
448 /* x86-64 should always use SA_RESTORER. */
449 if (ka->sa.sa_flags & SA_RESTORER) {
450 put_user_ex(ka->sa.sa_restorer, &frame->pretcode);
451 } else {
452 /* could use a vstub here */
453 err |= -EFAULT;
454 }
455 } put_user_catch(err);
456
457 if (err)
458 return -EFAULT;
459
460 /* Set up registers for signal handler */
461 regs->di = sig;
462 /* In case the signal handler was declared without prototypes */
463 regs->ax = 0;
464
465 /* This also works for non SA_SIGINFO handlers because they expect the
466 next argument after the signal number on the stack. */
467 regs->si = (unsigned long)&frame->info;
468 regs->dx = (unsigned long)&frame->uc;
469 regs->ip = (unsigned long) ka->sa.sa_handler;
470
471 regs->sp = (unsigned long)frame;
472
473 /* Set up the CS register to run signal handlers in 64-bit mode,
474 even if the handler happens to be interrupting 32-bit code. */
475 regs->cs = __USER_CS;
476
477 return 0;
478}
479#endif /* CONFIG_X86_32 */
480
481#ifdef CONFIG_X86_32
482/*
483 * Atomically swap in the new signal mask, and wait for a signal.
484 */
485asmlinkage int
486sys_sigsuspend(int history0, int history1, old_sigset_t mask)
487{
488 sigset_t blocked;
489
490 current->saved_sigmask = current->blocked;
491
492 mask &= _BLOCKABLE;
493 siginitset(&blocked, mask);
494 set_current_blocked(&blocked);
495
496 current->state = TASK_INTERRUPTIBLE;
497 schedule();
498
499 set_restore_sigmask();
500 return -ERESTARTNOHAND;
501}
502
503asmlinkage int
504sys_sigaction(int sig, const struct old_sigaction __user *act,
505 struct old_sigaction __user *oact)
506{
507 struct k_sigaction new_ka, old_ka;
508 int ret = 0;
509
510 if (act) {
511 old_sigset_t mask;
512
513 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
514 return -EFAULT;
515
516 get_user_try {
517 get_user_ex(new_ka.sa.sa_handler, &act->sa_handler);
518 get_user_ex(new_ka.sa.sa_flags, &act->sa_flags);
519 get_user_ex(mask, &act->sa_mask);
520 get_user_ex(new_ka.sa.sa_restorer, &act->sa_restorer);
521 } get_user_catch(ret);
522
523 if (ret)
524 return -EFAULT;
525 siginitset(&new_ka.sa.sa_mask, mask);
526 }
527
528 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
529
530 if (!ret && oact) {
531 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
532 return -EFAULT;
533
534 put_user_try {
535 put_user_ex(old_ka.sa.sa_handler, &oact->sa_handler);
536 put_user_ex(old_ka.sa.sa_flags, &oact->sa_flags);
537 put_user_ex(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
538 put_user_ex(old_ka.sa.sa_restorer, &oact->sa_restorer);
539 } put_user_catch(ret);
540
541 if (ret)
542 return -EFAULT;
543 }
544
545 return ret;
546}
547#endif /* CONFIG_X86_32 */
548
549long
550sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
551 struct pt_regs *regs)
552{
553 return do_sigaltstack(uss, uoss, regs->sp);
554}
555
556/*
557 * Do a signal return; undo the signal stack.
558 */
559#ifdef CONFIG_X86_32
560unsigned long sys_sigreturn(struct pt_regs *regs)
561{
562 struct sigframe __user *frame;
563 unsigned long ax;
564 sigset_t set;
565
566 frame = (struct sigframe __user *)(regs->sp - 8);
567
568 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
569 goto badframe;
570 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
571 && __copy_from_user(&set.sig[1], &frame->extramask,
572 sizeof(frame->extramask))))
573 goto badframe;
574
575 sigdelsetmask(&set, ~_BLOCKABLE);
576 set_current_blocked(&set);
577
578 if (restore_sigcontext(regs, &frame->sc, &ax))
579 goto badframe;
580 return ax;
581
582badframe:
583 signal_fault(regs, frame, "sigreturn");
584
585 return 0;
586}
587#endif /* CONFIG_X86_32 */
588
589long sys_rt_sigreturn(struct pt_regs *regs)
590{
591 struct rt_sigframe __user *frame;
592 unsigned long ax;
593 sigset_t set;
594
595 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
596 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
597 goto badframe;
598 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
599 goto badframe;
600
601 sigdelsetmask(&set, ~_BLOCKABLE);
602 set_current_blocked(&set);
603
604 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
605 goto badframe;
606
607 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
608 goto badframe;
609
610 return ax;
611
612badframe:
613 signal_fault(regs, frame, "rt_sigreturn");
614 return 0;
615}
616
617/*
618 * OK, we're invoking a handler:
619 */
620static int signr_convert(int sig)
621{
622#ifdef CONFIG_X86_32
623 struct thread_info *info = current_thread_info();
624
625 if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
626 return info->exec_domain->signal_invmap[sig];
627#endif /* CONFIG_X86_32 */
628 return sig;
629}
630
631#ifdef CONFIG_X86_32
632
633#define is_ia32 1
634#define ia32_setup_frame __setup_frame
635#define ia32_setup_rt_frame __setup_rt_frame
636
637#else /* !CONFIG_X86_32 */
638
639#ifdef CONFIG_IA32_EMULATION
640#define is_ia32 test_thread_flag(TIF_IA32)
641#else /* !CONFIG_IA32_EMULATION */
642#define is_ia32 0
643#endif /* CONFIG_IA32_EMULATION */
644
645int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
646 sigset_t *set, struct pt_regs *regs);
647int ia32_setup_frame(int sig, struct k_sigaction *ka,
648 sigset_t *set, struct pt_regs *regs);
649
650#endif /* CONFIG_X86_32 */
651
652static int
653setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
654 struct pt_regs *regs)
655{
656 int usig = signr_convert(sig);
657 sigset_t *set = ¤t->blocked;
658 int ret;
659
660 if (current_thread_info()->status & TS_RESTORE_SIGMASK)
661 set = ¤t->saved_sigmask;
662
663 /* Set up the stack frame */
664 if (is_ia32) {
665 if (ka->sa.sa_flags & SA_SIGINFO)
666 ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
667 else
668 ret = ia32_setup_frame(usig, ka, set, regs);
669 } else
670 ret = __setup_rt_frame(sig, ka, info, set, regs);
671
672 if (ret) {
673 force_sigsegv(sig, current);
674 return -EFAULT;
675 }
676
677 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
678 return ret;
679}
680
681static int
682handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
683 struct pt_regs *regs)
684{
685 sigset_t blocked;
686 int ret;
687
688 /* Are we from a system call? */
689 if (syscall_get_nr(current, regs) >= 0) {
690 /* If so, check system call restarting.. */
691 switch (syscall_get_error(current, regs)) {
692 case -ERESTART_RESTARTBLOCK:
693 case -ERESTARTNOHAND:
694 regs->ax = -EINTR;
695 break;
696
697 case -ERESTARTSYS:
698 if (!(ka->sa.sa_flags & SA_RESTART)) {
699 regs->ax = -EINTR;
700 break;
701 }
702 /* fallthrough */
703 case -ERESTARTNOINTR:
704 regs->ax = regs->orig_ax;
705 regs->ip -= 2;
706 break;
707 }
708 }
709
710 /*
711 * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
712 * flag so that register information in the sigcontext is correct.
713 */
714 if (unlikely(regs->flags & X86_EFLAGS_TF) &&
715 likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
716 regs->flags &= ~X86_EFLAGS_TF;
717
718 ret = setup_rt_frame(sig, ka, info, regs);
719
720 if (ret)
721 return ret;
722
723 /*
724 * Clear the direction flag as per the ABI for function entry.
725 */
726 regs->flags &= ~X86_EFLAGS_DF;
727
728 /*
729 * Clear TF when entering the signal handler, but
730 * notify any tracer that was single-stepping it.
731 * The tracer may want to single-step inside the
732 * handler too.
733 */
734 regs->flags &= ~X86_EFLAGS_TF;
735
736 sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
737 if (!(ka->sa.sa_flags & SA_NODEFER))
738 sigaddset(&blocked, sig);
739 set_current_blocked(&blocked);
740
741 tracehook_signal_handler(sig, info, ka, regs,
742 test_thread_flag(TIF_SINGLESTEP));
743
744 return 0;
745}
746
747#ifdef CONFIG_X86_32
748#define NR_restart_syscall __NR_restart_syscall
749#else /* !CONFIG_X86_32 */
750#define NR_restart_syscall \
751 test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
752#endif /* CONFIG_X86_32 */
753
754/*
755 * Note that 'init' is a special process: it doesn't get signals it doesn't
756 * want to handle. Thus you cannot kill init even with a SIGKILL even by
757 * mistake.
758 */
759static void do_signal(struct pt_regs *regs)
760{
761 struct k_sigaction ka;
762 siginfo_t info;
763 int signr;
764
765 /*
766 * We want the common case to go fast, which is why we may in certain
767 * cases get here from kernel mode. Just return without doing anything
768 * if so.
769 * X86_32: vm86 regs switched out by assembly code before reaching
770 * here, so testing against kernel CS suffices.
771 */
772 if (!user_mode(regs))
773 return;
774
775 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
776 if (signr > 0) {
777 /* Whee! Actually deliver the signal. */
778 handle_signal(signr, &info, &ka, regs);
779 return;
780 }
781
782 /* Did we come from a system call? */
783 if (syscall_get_nr(current, regs) >= 0) {
784 /* Restart the system call - no handlers present */
785 switch (syscall_get_error(current, regs)) {
786 case -ERESTARTNOHAND:
787 case -ERESTARTSYS:
788 case -ERESTARTNOINTR:
789 regs->ax = regs->orig_ax;
790 regs->ip -= 2;
791 break;
792
793 case -ERESTART_RESTARTBLOCK:
794 regs->ax = NR_restart_syscall;
795 regs->ip -= 2;
796 break;
797 }
798 }
799
800 /*
801 * If there's no signal to deliver, we just put the saved sigmask
802 * back.
803 */
804 if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
805 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
806 set_current_blocked(¤t->saved_sigmask);
807 }
808}
809
810/*
811 * notification of userspace execution resumption
812 * - triggered by the TIF_WORK_MASK flags
813 */
814void
815do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
816{
817#ifdef CONFIG_X86_MCE
818 /* notify userspace of pending MCEs */
819 if (thread_info_flags & _TIF_MCE_NOTIFY)
820 mce_notify_process();
821#endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
822
823 /* deal with pending signal delivery */
824 if (thread_info_flags & _TIF_SIGPENDING)
825 do_signal(regs);
826
827 if (thread_info_flags & _TIF_NOTIFY_RESUME) {
828 clear_thread_flag(TIF_NOTIFY_RESUME);
829 tracehook_notify_resume(regs);
830 if (current->replacement_session_keyring)
831 key_replace_session_keyring();
832 }
833 if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
834 fire_user_return_notifiers();
835
836#ifdef CONFIG_X86_32
837 clear_thread_flag(TIF_IRET);
838#endif /* CONFIG_X86_32 */
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(" in ", regs->ip);
852 printk(KERN_CONT "\n");
853 }
854
855 force_sig(SIGSEGV, me);
856}