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 */
force_valid_ss(struct pt_regs * regs)56 static 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
restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * usc,unsigned long uc_flags)82 static 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
143 static __always_inline int
__unsafe_setup_sigcontext(struct sigcontext __user * sc,void __user * fpstate,struct pt_regs * regs,unsigned long mask)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;
196 Efault:
197 return -EFAULT;
198 }
199
200 #define unsafe_put_sigcontext(sc, fp, regs, set, label) \
201 do { \
202 if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \
203 goto label; \
204 } while(0);
205
206 #define unsafe_put_sigmask(set, frame, label) \
207 unsafe_put_user(*(__u64 *)(set), \
208 (__u64 __user *)&(frame)->uc.uc_sigmask, \
209 label)
210
211 /*
212 * Set up a signal frame.
213 */
214
215 /*
216 * Determine which stack to use..
217 */
align_sigframe(unsigned long sp)218 static unsigned long align_sigframe(unsigned long sp)
219 {
220 #ifdef CONFIG_X86_32
221 /*
222 * Align the stack pointer according to the i386 ABI,
223 * i.e. so that on function entry ((sp + 4) & 15) == 0.
224 */
225 sp = ((sp + 4) & -16ul) - 4;
226 #else /* !CONFIG_X86_32 */
227 sp = round_down(sp, 16) - 8;
228 #endif
229 return sp;
230 }
231
232 static void __user *
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,size_t frame_size,void __user ** fpstate)233 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
234 void __user **fpstate)
235 {
236 /* Default to using normal stack */
237 bool nested_altstack = on_sig_stack(regs->sp);
238 bool entering_altstack = false;
239 unsigned long math_size = 0;
240 unsigned long sp = regs->sp;
241 unsigned long buf_fx = 0;
242 int ret;
243
244 /* redzone */
245 if (IS_ENABLED(CONFIG_X86_64))
246 sp -= 128;
247
248 /* This is the X/Open sanctioned signal stack switching. */
249 if (ka->sa.sa_flags & SA_ONSTACK) {
250 /*
251 * This checks nested_altstack via sas_ss_flags(). Sensible
252 * programs use SS_AUTODISARM, which disables that check, and
253 * programs that don't use SS_AUTODISARM get compatible.
254 */
255 if (sas_ss_flags(sp) == 0) {
256 sp = current->sas_ss_sp + current->sas_ss_size;
257 entering_altstack = true;
258 }
259 } else if (IS_ENABLED(CONFIG_X86_32) &&
260 !nested_altstack &&
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 entering_altstack = true;
267 }
268
269 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
270 &buf_fx, &math_size);
271 *fpstate = (void __user *)sp;
272
273 sp = align_sigframe(sp - frame_size);
274
275 /*
276 * If we are on the alternate signal stack and would overflow it, don't.
277 * Return an always-bogus address instead so we will die with SIGSEGV.
278 */
279 if (unlikely((nested_altstack || entering_altstack) &&
280 !__on_sig_stack(sp))) {
281
282 if (show_unhandled_signals && printk_ratelimit())
283 pr_info("%s[%d] overflowed sigaltstack\n",
284 current->comm, task_pid_nr(current));
285
286 return (void __user *)-1L;
287 }
288
289 /* save i387 and extended state */
290 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size);
291 if (ret < 0)
292 return (void __user *)-1L;
293
294 return (void __user *)sp;
295 }
296
297 #ifdef CONFIG_X86_32
298 static const struct {
299 u16 poplmovl;
300 u32 val;
301 u16 int80;
302 } __attribute__((packed)) retcode = {
303 0xb858, /* popl %eax; movl $..., %eax */
304 __NR_sigreturn,
305 0x80cd, /* int $0x80 */
306 };
307
308 static const struct {
309 u8 movl;
310 u32 val;
311 u16 int80;
312 u8 pad;
313 } __attribute__((packed)) rt_retcode = {
314 0xb8, /* movl $..., %eax */
315 __NR_rt_sigreturn,
316 0x80cd, /* int $0x80 */
317 0
318 };
319
320 static int
__setup_frame(int sig,struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)321 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
322 struct pt_regs *regs)
323 {
324 struct sigframe __user *frame;
325 void __user *restorer;
326 void __user *fp = NULL;
327
328 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
329
330 if (!user_access_begin(frame, sizeof(*frame)))
331 return -EFAULT;
332
333 unsafe_put_user(sig, &frame->sig, Efault);
334 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault);
335 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
336 if (current->mm->context.vdso)
337 restorer = current->mm->context.vdso +
338 vdso_image_32.sym___kernel_sigreturn;
339 else
340 restorer = &frame->retcode;
341 if (ksig->ka.sa.sa_flags & SA_RESTORER)
342 restorer = ksig->ka.sa.sa_restorer;
343
344 /* Set up to return from userspace. */
345 unsafe_put_user(restorer, &frame->pretcode, Efault);
346
347 /*
348 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
349 *
350 * WE DO NOT USE IT ANY MORE! It's only left here for historical
351 * reasons and because gdb uses it as a signature to notice
352 * signal handler stack frames.
353 */
354 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
355 user_access_end();
356
357 /* Set up registers for signal handler */
358 regs->sp = (unsigned long)frame;
359 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
360 regs->ax = (unsigned long)sig;
361 regs->dx = 0;
362 regs->cx = 0;
363
364 regs->ds = __USER_DS;
365 regs->es = __USER_DS;
366 regs->ss = __USER_DS;
367 regs->cs = __USER_CS;
368
369 return 0;
370
371 Efault:
372 user_access_end();
373 return -EFAULT;
374 }
375
__setup_rt_frame(int sig,struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)376 static int __setup_rt_frame(int sig, struct ksignal *ksig,
377 sigset_t *set, struct pt_regs *regs)
378 {
379 struct rt_sigframe __user *frame;
380 void __user *restorer;
381 void __user *fp = NULL;
382
383 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
384
385 if (!user_access_begin(frame, sizeof(*frame)))
386 return -EFAULT;
387
388 unsafe_put_user(sig, &frame->sig, Efault);
389 unsafe_put_user(&frame->info, &frame->pinfo, Efault);
390 unsafe_put_user(&frame->uc, &frame->puc, Efault);
391
392 /* Create the ucontext. */
393 if (static_cpu_has(X86_FEATURE_XSAVE))
394 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
395 else
396 unsafe_put_user(0, &frame->uc.uc_flags, Efault);
397 unsafe_put_user(0, &frame->uc.uc_link, Efault);
398 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
399
400 /* Set up to return from userspace. */
401 restorer = current->mm->context.vdso +
402 vdso_image_32.sym___kernel_rt_sigreturn;
403 if (ksig->ka.sa.sa_flags & SA_RESTORER)
404 restorer = ksig->ka.sa.sa_restorer;
405 unsafe_put_user(restorer, &frame->pretcode, Efault);
406
407 /*
408 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
409 *
410 * WE DO NOT USE IT ANY MORE! It's only left here for historical
411 * reasons and because gdb uses it as a signature to notice
412 * signal handler stack frames.
413 */
414 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
415 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
416 unsafe_put_sigmask(set, frame, Efault);
417 user_access_end();
418
419 if (copy_siginfo_to_user(&frame->info, &ksig->info))
420 return -EFAULT;
421
422 /* Set up registers for signal handler */
423 regs->sp = (unsigned long)frame;
424 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
425 regs->ax = (unsigned long)sig;
426 regs->dx = (unsigned long)&frame->info;
427 regs->cx = (unsigned long)&frame->uc;
428
429 regs->ds = __USER_DS;
430 regs->es = __USER_DS;
431 regs->ss = __USER_DS;
432 regs->cs = __USER_CS;
433
434 return 0;
435 Efault:
436 user_access_end();
437 return -EFAULT;
438 }
439 #else /* !CONFIG_X86_32 */
frame_uc_flags(struct pt_regs * regs)440 static unsigned long frame_uc_flags(struct pt_regs *regs)
441 {
442 unsigned long flags;
443
444 if (boot_cpu_has(X86_FEATURE_XSAVE))
445 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
446 else
447 flags = UC_SIGCONTEXT_SS;
448
449 if (likely(user_64bit_mode(regs)))
450 flags |= UC_STRICT_RESTORE_SS;
451
452 return flags;
453 }
454
__setup_rt_frame(int sig,struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)455 static int __setup_rt_frame(int sig, struct ksignal *ksig,
456 sigset_t *set, struct pt_regs *regs)
457 {
458 struct rt_sigframe __user *frame;
459 void __user *fp = NULL;
460 unsigned long uc_flags;
461
462 /* x86-64 should always use SA_RESTORER. */
463 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
464 return -EFAULT;
465
466 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
467 uc_flags = frame_uc_flags(regs);
468
469 if (!user_access_begin(frame, sizeof(*frame)))
470 return -EFAULT;
471
472 /* Create the ucontext. */
473 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
474 unsafe_put_user(0, &frame->uc.uc_link, Efault);
475 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
476
477 /* Set up to return from userspace. If provided, use a stub
478 already in userspace. */
479 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
480 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
481 unsafe_put_sigmask(set, frame, Efault);
482 user_access_end();
483
484 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
485 if (copy_siginfo_to_user(&frame->info, &ksig->info))
486 return -EFAULT;
487 }
488
489 /* Set up registers for signal handler */
490 regs->di = sig;
491 /* In case the signal handler was declared without prototypes */
492 regs->ax = 0;
493
494 /* This also works for non SA_SIGINFO handlers because they expect the
495 next argument after the signal number on the stack. */
496 regs->si = (unsigned long)&frame->info;
497 regs->dx = (unsigned long)&frame->uc;
498 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
499
500 regs->sp = (unsigned long)frame;
501
502 /*
503 * Set up the CS and SS registers to run signal handlers in
504 * 64-bit mode, even if the handler happens to be interrupting
505 * 32-bit or 16-bit code.
506 *
507 * SS is subtle. In 64-bit mode, we don't need any particular
508 * SS descriptor, but we do need SS to be valid. It's possible
509 * that the old SS is entirely bogus -- this can happen if the
510 * signal we're trying to deliver is #GP or #SS caused by a bad
511 * SS value. We also have a compatbility issue here: DOSEMU
512 * relies on the contents of the SS register indicating the
513 * SS value at the time of the signal, even though that code in
514 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
515 * avoids relying on sigreturn to restore SS; instead it uses
516 * a trampoline.) So we do our best: if the old SS was valid,
517 * we keep it. Otherwise we replace it.
518 */
519 regs->cs = __USER_CS;
520
521 if (unlikely(regs->ss != __USER_DS))
522 force_valid_ss(regs);
523
524 return 0;
525
526 Efault:
527 user_access_end();
528 return -EFAULT;
529 }
530 #endif /* CONFIG_X86_32 */
531
532 #ifdef CONFIG_X86_X32_ABI
x32_copy_siginfo_to_user(struct compat_siginfo __user * to,const struct kernel_siginfo * from)533 static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
534 const struct kernel_siginfo *from)
535 {
536 struct compat_siginfo new;
537
538 copy_siginfo_to_external32(&new, from);
539 if (from->si_signo == SIGCHLD) {
540 new._sifields._sigchld_x32._utime = from->si_utime;
541 new._sifields._sigchld_x32._stime = from->si_stime;
542 }
543 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
544 return -EFAULT;
545 return 0;
546 }
547
copy_siginfo_to_user32(struct compat_siginfo __user * to,const struct kernel_siginfo * from)548 int copy_siginfo_to_user32(struct compat_siginfo __user *to,
549 const struct kernel_siginfo *from)
550 {
551 if (in_x32_syscall())
552 return x32_copy_siginfo_to_user(to, from);
553 return __copy_siginfo_to_user32(to, from);
554 }
555 #endif /* CONFIG_X86_X32_ABI */
556
x32_setup_rt_frame(struct ksignal * ksig,compat_sigset_t * set,struct pt_regs * regs)557 static int x32_setup_rt_frame(struct ksignal *ksig,
558 compat_sigset_t *set,
559 struct pt_regs *regs)
560 {
561 #ifdef CONFIG_X86_X32_ABI
562 struct rt_sigframe_x32 __user *frame;
563 unsigned long uc_flags;
564 void __user *restorer;
565 void __user *fp = NULL;
566
567 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
568 return -EFAULT;
569
570 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
571
572 uc_flags = frame_uc_flags(regs);
573
574 if (!user_access_begin(frame, sizeof(*frame)))
575 return -EFAULT;
576
577 /* Create the ucontext. */
578 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
579 unsafe_put_user(0, &frame->uc.uc_link, Efault);
580 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
581 unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
582 restorer = ksig->ka.sa.sa_restorer;
583 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
584 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
585 unsafe_put_sigmask(set, frame, Efault);
586 user_access_end();
587
588 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
589 if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
590 return -EFAULT;
591 }
592
593 /* Set up registers for signal handler */
594 regs->sp = (unsigned long) frame;
595 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
596
597 /* We use the x32 calling convention here... */
598 regs->di = ksig->sig;
599 regs->si = (unsigned long) &frame->info;
600 regs->dx = (unsigned long) &frame->uc;
601
602 loadsegment(ds, __USER_DS);
603 loadsegment(es, __USER_DS);
604
605 regs->cs = __USER_CS;
606 regs->ss = __USER_DS;
607 #endif /* CONFIG_X86_X32_ABI */
608
609 return 0;
610 #ifdef CONFIG_X86_X32_ABI
611 Efault:
612 user_access_end();
613 return -EFAULT;
614 #endif
615 }
616
617 /*
618 * Do a signal return; undo the signal stack.
619 */
620 #ifdef CONFIG_X86_32
SYSCALL_DEFINE0(sigreturn)621 SYSCALL_DEFINE0(sigreturn)
622 {
623 struct pt_regs *regs = current_pt_regs();
624 struct sigframe __user *frame;
625 sigset_t set;
626
627 frame = (struct sigframe __user *)(regs->sp - 8);
628
629 if (!access_ok(frame, sizeof(*frame)))
630 goto badframe;
631 if (__get_user(set.sig[0], &frame->sc.oldmask) ||
632 __get_user(set.sig[1], &frame->extramask[0]))
633 goto badframe;
634
635 set_current_blocked(&set);
636
637 /*
638 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
639 * Save a few cycles by skipping the __get_user.
640 */
641 if (restore_sigcontext(regs, &frame->sc, 0))
642 goto badframe;
643 return regs->ax;
644
645 badframe:
646 signal_fault(regs, frame, "sigreturn");
647
648 return 0;
649 }
650 #endif /* CONFIG_X86_32 */
651
SYSCALL_DEFINE0(rt_sigreturn)652 SYSCALL_DEFINE0(rt_sigreturn)
653 {
654 struct pt_regs *regs = current_pt_regs();
655 struct rt_sigframe __user *frame;
656 sigset_t set;
657 unsigned long uc_flags;
658
659 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
660 if (!access_ok(frame, sizeof(*frame)))
661 goto badframe;
662 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
663 goto badframe;
664 if (__get_user(uc_flags, &frame->uc.uc_flags))
665 goto badframe;
666
667 set_current_blocked(&set);
668
669 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
670 goto badframe;
671
672 if (restore_altstack(&frame->uc.uc_stack))
673 goto badframe;
674
675 return regs->ax;
676
677 badframe:
678 signal_fault(regs, frame, "rt_sigreturn");
679 return 0;
680 }
681
is_ia32_compat_frame(struct ksignal * ksig)682 static inline int is_ia32_compat_frame(struct ksignal *ksig)
683 {
684 return IS_ENABLED(CONFIG_IA32_EMULATION) &&
685 ksig->ka.sa.sa_flags & SA_IA32_ABI;
686 }
687
is_ia32_frame(struct ksignal * ksig)688 static inline int is_ia32_frame(struct ksignal *ksig)
689 {
690 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
691 }
692
is_x32_frame(struct ksignal * ksig)693 static inline int is_x32_frame(struct ksignal *ksig)
694 {
695 return IS_ENABLED(CONFIG_X86_X32_ABI) &&
696 ksig->ka.sa.sa_flags & SA_X32_ABI;
697 }
698
699 static int
setup_rt_frame(struct ksignal * ksig,struct pt_regs * regs)700 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
701 {
702 int usig = ksig->sig;
703 sigset_t *set = sigmask_to_save();
704 compat_sigset_t *cset = (compat_sigset_t *) set;
705
706 /* Perform fixup for the pre-signal frame. */
707 rseq_signal_deliver(ksig, regs);
708
709 /* Set up the stack frame */
710 if (is_ia32_frame(ksig)) {
711 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
712 return ia32_setup_rt_frame(usig, ksig, cset, regs);
713 else
714 return ia32_setup_frame(usig, ksig, cset, regs);
715 } else if (is_x32_frame(ksig)) {
716 return x32_setup_rt_frame(ksig, cset, regs);
717 } else {
718 return __setup_rt_frame(ksig->sig, ksig, set, regs);
719 }
720 }
721
722 static void
handle_signal(struct ksignal * ksig,struct pt_regs * regs)723 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
724 {
725 bool stepping, failed;
726 struct fpu *fpu = ¤t->thread.fpu;
727
728 if (v8086_mode(regs))
729 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
730
731 /* Are we from a system call? */
732 if (syscall_get_nr(current, regs) >= 0) {
733 /* If so, check system call restarting.. */
734 switch (syscall_get_error(current, regs)) {
735 case -ERESTART_RESTARTBLOCK:
736 case -ERESTARTNOHAND:
737 regs->ax = -EINTR;
738 break;
739
740 case -ERESTARTSYS:
741 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
742 regs->ax = -EINTR;
743 break;
744 }
745 fallthrough;
746 case -ERESTARTNOINTR:
747 regs->ax = regs->orig_ax;
748 regs->ip -= 2;
749 break;
750 }
751 }
752
753 /*
754 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
755 * so that register information in the sigcontext is correct and
756 * then notify the tracer before entering the signal handler.
757 */
758 stepping = test_thread_flag(TIF_SINGLESTEP);
759 if (stepping)
760 user_disable_single_step(current);
761
762 failed = (setup_rt_frame(ksig, regs) < 0);
763 if (!failed) {
764 /*
765 * Clear the direction flag as per the ABI for function entry.
766 *
767 * Clear RF when entering the signal handler, because
768 * it might disable possible debug exception from the
769 * signal handler.
770 *
771 * Clear TF for the case when it wasn't set by debugger to
772 * avoid the recursive send_sigtrap() in SIGTRAP handler.
773 */
774 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
775 /*
776 * Ensure the signal handler starts with the new fpu state.
777 */
778 fpu__clear_user_states(fpu);
779 }
780 signal_setup_done(failed, ksig, stepping);
781 }
782
get_nr_restart_syscall(const struct pt_regs * regs)783 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
784 {
785 #ifdef CONFIG_IA32_EMULATION
786 if (current_thread_info()->status & TS_COMPAT_RESTART)
787 return __NR_ia32_restart_syscall;
788 #endif
789 #ifdef CONFIG_X86_X32_ABI
790 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
791 #else
792 return __NR_restart_syscall;
793 #endif
794 }
795
796 /*
797 * Note that 'init' is a special process: it doesn't get signals it doesn't
798 * want to handle. Thus you cannot kill init even with a SIGKILL even by
799 * mistake.
800 */
arch_do_signal_or_restart(struct pt_regs * regs,bool has_signal)801 void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
802 {
803 struct ksignal ksig;
804
805 if (has_signal && get_signal(&ksig)) {
806 /* Whee! Actually deliver the signal. */
807 handle_signal(&ksig, regs);
808 return;
809 }
810
811 /* Did we come from a system call? */
812 if (syscall_get_nr(current, regs) >= 0) {
813 /* Restart the system call - no handlers present */
814 switch (syscall_get_error(current, regs)) {
815 case -ERESTARTNOHAND:
816 case -ERESTARTSYS:
817 case -ERESTARTNOINTR:
818 regs->ax = regs->orig_ax;
819 regs->ip -= 2;
820 break;
821
822 case -ERESTART_RESTARTBLOCK:
823 regs->ax = get_nr_restart_syscall(regs);
824 regs->ip -= 2;
825 break;
826 }
827 }
828
829 /*
830 * If there's no signal to deliver, we just put the saved sigmask
831 * back.
832 */
833 restore_saved_sigmask();
834 }
835
signal_fault(struct pt_regs * regs,void __user * frame,char * where)836 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
837 {
838 struct task_struct *me = current;
839
840 if (show_unhandled_signals && printk_ratelimit()) {
841 printk("%s"
842 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
843 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
844 me->comm, me->pid, where, frame,
845 regs->ip, regs->sp, regs->orig_ax);
846 print_vma_addr(KERN_CONT " in ", regs->ip);
847 pr_cont("\n");
848 }
849
850 force_sig(SIGSEGV);
851 }
852
853 #ifdef CONFIG_X86_X32_ABI
COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)854 COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
855 {
856 struct pt_regs *regs = current_pt_regs();
857 struct rt_sigframe_x32 __user *frame;
858 sigset_t set;
859 unsigned long uc_flags;
860
861 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
862
863 if (!access_ok(frame, sizeof(*frame)))
864 goto badframe;
865 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
866 goto badframe;
867 if (__get_user(uc_flags, &frame->uc.uc_flags))
868 goto badframe;
869
870 set_current_blocked(&set);
871
872 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
873 goto badframe;
874
875 if (compat_restore_altstack(&frame->uc.uc_stack))
876 goto badframe;
877
878 return regs->ax;
879
880 badframe:
881 signal_fault(regs, frame, "x32 rt_sigreturn");
882 return 0;
883 }
884 #endif
885