Line data Source code
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 : */
56 0 : static void force_valid_ss(struct pt_regs *regs)
57 : {
58 0 : u32 ar;
59 0 : 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 0 : : [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 0 : ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
73 0 : if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
74 0 : ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
75 0 : regs->ss = __USER_DS;
76 0 : }
77 : # define CONTEXT_COPY_SIZE offsetof(struct sigcontext, reserved1)
78 : #else
79 : # define CONTEXT_COPY_SIZE sizeof(struct sigcontext)
80 : #endif
81 :
82 1265 : static int restore_sigcontext(struct pt_regs *regs,
83 : struct sigcontext __user *usc,
84 : unsigned long uc_flags)
85 : {
86 1265 : struct sigcontext sc;
87 :
88 : /* Always make any pending restarted system calls return -EINTR */
89 1265 : current->restart_block.fn = do_no_restart_syscall;
90 :
91 1265 : 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 1265 : regs->bx = sc.bx;
102 1265 : regs->cx = sc.cx;
103 1265 : regs->dx = sc.dx;
104 1265 : regs->si = sc.si;
105 1265 : regs->di = sc.di;
106 1265 : regs->bp = sc.bp;
107 1265 : regs->ax = sc.ax;
108 1265 : regs->sp = sc.sp;
109 1265 : regs->ip = sc.ip;
110 :
111 : #ifdef CONFIG_X86_64
112 1265 : regs->r8 = sc.r8;
113 1265 : regs->r9 = sc.r9;
114 1265 : regs->r10 = sc.r10;
115 1265 : regs->r11 = sc.r11;
116 1265 : regs->r12 = sc.r12;
117 1265 : regs->r13 = sc.r13;
118 1265 : regs->r14 = sc.r14;
119 1265 : regs->r15 = sc.r15;
120 : #endif /* CONFIG_X86_64 */
121 :
122 : /* Get CS/SS and force CPL3 */
123 1265 : regs->cs = sc.cs | 0x03;
124 1265 : regs->ss = sc.ss | 0x03;
125 :
126 1265 : regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
127 : /* disable syscall checks */
128 1265 : 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 1265 : if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
136 0 : force_valid_ss(regs);
137 : #endif
138 :
139 1265 : return fpu__restore_sig((void __user *)sc.fpstate,
140 : IS_ENABLED(CONFIG_X86_32));
141 : }
142 :
143 : static __always_inline int
144 1265 : __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 1265 : unsafe_put_user(regs->di, &sc->di, Efault);
156 1265 : unsafe_put_user(regs->si, &sc->si, Efault);
157 1265 : unsafe_put_user(regs->bp, &sc->bp, Efault);
158 1265 : unsafe_put_user(regs->sp, &sc->sp, Efault);
159 1265 : unsafe_put_user(regs->bx, &sc->bx, Efault);
160 1265 : unsafe_put_user(regs->dx, &sc->dx, Efault);
161 1265 : unsafe_put_user(regs->cx, &sc->cx, Efault);
162 1265 : unsafe_put_user(regs->ax, &sc->ax, Efault);
163 : #ifdef CONFIG_X86_64
164 1265 : unsafe_put_user(regs->r8, &sc->r8, Efault);
165 1265 : unsafe_put_user(regs->r9, &sc->r9, Efault);
166 1265 : unsafe_put_user(regs->r10, &sc->r10, Efault);
167 1265 : unsafe_put_user(regs->r11, &sc->r11, Efault);
168 1265 : unsafe_put_user(regs->r12, &sc->r12, Efault);
169 1265 : unsafe_put_user(regs->r13, &sc->r13, Efault);
170 1265 : unsafe_put_user(regs->r14, &sc->r14, Efault);
171 1265 : unsafe_put_user(regs->r15, &sc->r15, Efault);
172 : #endif /* CONFIG_X86_64 */
173 :
174 1265 : unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
175 1265 : unsafe_put_user(current->thread.error_code, &sc->err, Efault);
176 1265 : 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 1265 : unsafe_put_user(regs->flags, &sc->flags, Efault);
184 1265 : unsafe_put_user(regs->cs, &sc->cs, Efault);
185 1265 : unsafe_put_user(0, &sc->gs, Efault);
186 1265 : unsafe_put_user(0, &sc->fs, Efault);
187 1265 : unsafe_put_user(regs->ss, &sc->ss, Efault);
188 : #endif /* CONFIG_X86_32 */
189 :
190 1265 : unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault);
191 :
192 : /* non-iBCS2 extensions.. */
193 1265 : unsafe_put_user(mask, &sc->oldmask, Efault);
194 1265 : unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
195 1265 : 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 : */
218 1265 : 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 1265 : sp = round_down(sp, 16) - 8;
228 : #endif
229 1265 : return sp;
230 : }
231 :
232 : static void __user *
233 1265 : 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 1265 : unsigned long math_size = 0;
238 1265 : unsigned long sp = regs->sp;
239 1265 : unsigned long buf_fx = 0;
240 1265 : int onsigstack = on_sig_stack(sp);
241 1265 : int ret;
242 :
243 : /* redzone */
244 1265 : if (IS_ENABLED(CONFIG_X86_64))
245 1265 : sp -= 128;
246 :
247 : /* This is the X/Open sanctioned signal stack switching. */
248 1265 : if (ka->sa.sa_flags & SA_ONSTACK) {
249 0 : if (sas_ss_flags(sp) == 0)
250 0 : sp = current->sas_ss_sp + current->sas_ss_size;
251 : } else if (IS_ENABLED(CONFIG_X86_32) &&
252 : !onsigstack &&
253 : regs->ss != __USER_DS &&
254 : !(ka->sa.sa_flags & SA_RESTORER) &&
255 : ka->sa.sa_restorer) {
256 : /* This is the legacy signal stack switching. */
257 : sp = (unsigned long) ka->sa.sa_restorer;
258 : }
259 :
260 1265 : sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
261 : &buf_fx, &math_size);
262 1265 : *fpstate = (void __user *)sp;
263 :
264 1265 : sp = align_sigframe(sp - frame_size);
265 :
266 : /*
267 : * If we are on the alternate signal stack and would overflow it, don't.
268 : * Return an always-bogus address instead so we will die with SIGSEGV.
269 : */
270 1265 : if (onsigstack && !likely(on_sig_stack(sp)))
271 : return (void __user *)-1L;
272 :
273 : /* save i387 and extended state */
274 1265 : ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size);
275 1265 : if (ret < 0)
276 : return (void __user *)-1L;
277 :
278 1265 : return (void __user *)sp;
279 : }
280 :
281 : #ifdef CONFIG_X86_32
282 : static const struct {
283 : u16 poplmovl;
284 : u32 val;
285 : u16 int80;
286 : } __attribute__((packed)) retcode = {
287 : 0xb858, /* popl %eax; movl $..., %eax */
288 : __NR_sigreturn,
289 : 0x80cd, /* int $0x80 */
290 : };
291 :
292 : static const struct {
293 : u8 movl;
294 : u32 val;
295 : u16 int80;
296 : u8 pad;
297 : } __attribute__((packed)) rt_retcode = {
298 : 0xb8, /* movl $..., %eax */
299 : __NR_rt_sigreturn,
300 : 0x80cd, /* int $0x80 */
301 : 0
302 : };
303 :
304 : static int
305 : __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
306 : struct pt_regs *regs)
307 : {
308 : struct sigframe __user *frame;
309 : void __user *restorer;
310 : void __user *fp = NULL;
311 :
312 : frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
313 :
314 : if (!user_access_begin(frame, sizeof(*frame)))
315 : return -EFAULT;
316 :
317 : unsafe_put_user(sig, &frame->sig, Efault);
318 : unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault);
319 : unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
320 : if (current->mm->context.vdso)
321 : restorer = current->mm->context.vdso +
322 : vdso_image_32.sym___kernel_sigreturn;
323 : else
324 : restorer = &frame->retcode;
325 : if (ksig->ka.sa.sa_flags & SA_RESTORER)
326 : restorer = ksig->ka.sa.sa_restorer;
327 :
328 : /* Set up to return from userspace. */
329 : unsafe_put_user(restorer, &frame->pretcode, Efault);
330 :
331 : /*
332 : * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
333 : *
334 : * WE DO NOT USE IT ANY MORE! It's only left here for historical
335 : * reasons and because gdb uses it as a signature to notice
336 : * signal handler stack frames.
337 : */
338 : unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
339 : user_access_end();
340 :
341 : /* Set up registers for signal handler */
342 : regs->sp = (unsigned long)frame;
343 : regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
344 : regs->ax = (unsigned long)sig;
345 : regs->dx = 0;
346 : regs->cx = 0;
347 :
348 : regs->ds = __USER_DS;
349 : regs->es = __USER_DS;
350 : regs->ss = __USER_DS;
351 : regs->cs = __USER_CS;
352 :
353 : return 0;
354 :
355 : Efault:
356 : user_access_end();
357 : return -EFAULT;
358 : }
359 :
360 : static int __setup_rt_frame(int sig, struct ksignal *ksig,
361 : sigset_t *set, struct pt_regs *regs)
362 : {
363 : struct rt_sigframe __user *frame;
364 : void __user *restorer;
365 : void __user *fp = NULL;
366 :
367 : frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
368 :
369 : if (!user_access_begin(frame, sizeof(*frame)))
370 : return -EFAULT;
371 :
372 : unsafe_put_user(sig, &frame->sig, Efault);
373 : unsafe_put_user(&frame->info, &frame->pinfo, Efault);
374 : unsafe_put_user(&frame->uc, &frame->puc, Efault);
375 :
376 : /* Create the ucontext. */
377 : if (static_cpu_has(X86_FEATURE_XSAVE))
378 : unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
379 : else
380 : unsafe_put_user(0, &frame->uc.uc_flags, Efault);
381 : unsafe_put_user(0, &frame->uc.uc_link, Efault);
382 : unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
383 :
384 : /* Set up to return from userspace. */
385 : restorer = current->mm->context.vdso +
386 : vdso_image_32.sym___kernel_rt_sigreturn;
387 : if (ksig->ka.sa.sa_flags & SA_RESTORER)
388 : restorer = ksig->ka.sa.sa_restorer;
389 : unsafe_put_user(restorer, &frame->pretcode, Efault);
390 :
391 : /*
392 : * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
393 : *
394 : * WE DO NOT USE IT ANY MORE! It's only left here for historical
395 : * reasons and because gdb uses it as a signature to notice
396 : * signal handler stack frames.
397 : */
398 : unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
399 : unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
400 : unsafe_put_sigmask(set, frame, Efault);
401 : user_access_end();
402 :
403 : if (copy_siginfo_to_user(&frame->info, &ksig->info))
404 : return -EFAULT;
405 :
406 : /* Set up registers for signal handler */
407 : regs->sp = (unsigned long)frame;
408 : regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
409 : regs->ax = (unsigned long)sig;
410 : regs->dx = (unsigned long)&frame->info;
411 : regs->cx = (unsigned long)&frame->uc;
412 :
413 : regs->ds = __USER_DS;
414 : regs->es = __USER_DS;
415 : regs->ss = __USER_DS;
416 : regs->cs = __USER_CS;
417 :
418 : return 0;
419 : Efault:
420 : user_access_end();
421 : return -EFAULT;
422 : }
423 : #else /* !CONFIG_X86_32 */
424 1265 : static unsigned long frame_uc_flags(struct pt_regs *regs)
425 : {
426 1265 : unsigned long flags;
427 :
428 1265 : if (boot_cpu_has(X86_FEATURE_XSAVE))
429 : flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
430 : else
431 0 : flags = UC_SIGCONTEXT_SS;
432 :
433 1265 : if (likely(user_64bit_mode(regs)))
434 1265 : flags |= UC_STRICT_RESTORE_SS;
435 :
436 1265 : return flags;
437 : }
438 :
439 1265 : static int __setup_rt_frame(int sig, struct ksignal *ksig,
440 : sigset_t *set, struct pt_regs *regs)
441 : {
442 1265 : struct rt_sigframe __user *frame;
443 1265 : void __user *fp = NULL;
444 1265 : unsigned long uc_flags;
445 :
446 : /* x86-64 should always use SA_RESTORER. */
447 1265 : if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
448 : return -EFAULT;
449 :
450 1265 : frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
451 1265 : uc_flags = frame_uc_flags(regs);
452 :
453 1265 : if (!user_access_begin(frame, sizeof(*frame)))
454 : return -EFAULT;
455 :
456 : /* Create the ucontext. */
457 1265 : unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
458 1265 : unsafe_put_user(0, &frame->uc.uc_link, Efault);
459 1265 : unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
460 :
461 : /* Set up to return from userspace. If provided, use a stub
462 : already in userspace. */
463 1265 : unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
464 1265 : unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
465 1265 : unsafe_put_sigmask(set, frame, Efault);
466 1265 : user_access_end();
467 :
468 1265 : if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
469 0 : if (copy_siginfo_to_user(&frame->info, &ksig->info))
470 : return -EFAULT;
471 : }
472 :
473 : /* Set up registers for signal handler */
474 1265 : regs->di = sig;
475 : /* In case the signal handler was declared without prototypes */
476 1265 : regs->ax = 0;
477 :
478 : /* This also works for non SA_SIGINFO handlers because they expect the
479 : next argument after the signal number on the stack. */
480 1265 : regs->si = (unsigned long)&frame->info;
481 1265 : regs->dx = (unsigned long)&frame->uc;
482 1265 : regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
483 :
484 1265 : regs->sp = (unsigned long)frame;
485 :
486 : /*
487 : * Set up the CS and SS registers to run signal handlers in
488 : * 64-bit mode, even if the handler happens to be interrupting
489 : * 32-bit or 16-bit code.
490 : *
491 : * SS is subtle. In 64-bit mode, we don't need any particular
492 : * SS descriptor, but we do need SS to be valid. It's possible
493 : * that the old SS is entirely bogus -- this can happen if the
494 : * signal we're trying to deliver is #GP or #SS caused by a bad
495 : * SS value. We also have a compatbility issue here: DOSEMU
496 : * relies on the contents of the SS register indicating the
497 : * SS value at the time of the signal, even though that code in
498 : * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
499 : * avoids relying on sigreturn to restore SS; instead it uses
500 : * a trampoline.) So we do our best: if the old SS was valid,
501 : * we keep it. Otherwise we replace it.
502 : */
503 1265 : regs->cs = __USER_CS;
504 :
505 1265 : if (unlikely(regs->ss != __USER_DS))
506 0 : force_valid_ss(regs);
507 :
508 : return 0;
509 :
510 : Efault:
511 : user_access_end();
512 : return -EFAULT;
513 : }
514 : #endif /* CONFIG_X86_32 */
515 :
516 : #ifdef CONFIG_X86_X32_ABI
517 : static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
518 : const struct kernel_siginfo *from)
519 : {
520 : struct compat_siginfo new;
521 :
522 : copy_siginfo_to_external32(&new, from);
523 : if (from->si_signo == SIGCHLD) {
524 : new._sifields._sigchld_x32._utime = from->si_utime;
525 : new._sifields._sigchld_x32._stime = from->si_stime;
526 : }
527 : if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
528 : return -EFAULT;
529 : return 0;
530 : }
531 :
532 : int copy_siginfo_to_user32(struct compat_siginfo __user *to,
533 : const struct kernel_siginfo *from)
534 : {
535 : if (in_x32_syscall())
536 : return x32_copy_siginfo_to_user(to, from);
537 : return __copy_siginfo_to_user32(to, from);
538 : }
539 : #endif /* CONFIG_X86_X32_ABI */
540 :
541 : static int x32_setup_rt_frame(struct ksignal *ksig,
542 : compat_sigset_t *set,
543 : struct pt_regs *regs)
544 : {
545 : #ifdef CONFIG_X86_X32_ABI
546 : struct rt_sigframe_x32 __user *frame;
547 : unsigned long uc_flags;
548 : void __user *restorer;
549 : void __user *fp = NULL;
550 :
551 : if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
552 : return -EFAULT;
553 :
554 : frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
555 :
556 : uc_flags = frame_uc_flags(regs);
557 :
558 : if (!user_access_begin(frame, sizeof(*frame)))
559 : return -EFAULT;
560 :
561 : /* Create the ucontext. */
562 : unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
563 : unsafe_put_user(0, &frame->uc.uc_link, Efault);
564 : unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
565 : unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
566 : restorer = ksig->ka.sa.sa_restorer;
567 : unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
568 : unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
569 : unsafe_put_sigmask(set, frame, Efault);
570 : user_access_end();
571 :
572 : if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
573 : if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
574 : return -EFAULT;
575 : }
576 :
577 : /* Set up registers for signal handler */
578 : regs->sp = (unsigned long) frame;
579 : regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
580 :
581 : /* We use the x32 calling convention here... */
582 : regs->di = ksig->sig;
583 : regs->si = (unsigned long) &frame->info;
584 : regs->dx = (unsigned long) &frame->uc;
585 :
586 : loadsegment(ds, __USER_DS);
587 : loadsegment(es, __USER_DS);
588 :
589 : regs->cs = __USER_CS;
590 : regs->ss = __USER_DS;
591 : #endif /* CONFIG_X86_X32_ABI */
592 :
593 : return 0;
594 : #ifdef CONFIG_X86_X32_ABI
595 : Efault:
596 : user_access_end();
597 : return -EFAULT;
598 : #endif
599 : }
600 :
601 : /*
602 : * Do a signal return; undo the signal stack.
603 : */
604 : #ifdef CONFIG_X86_32
605 : SYSCALL_DEFINE0(sigreturn)
606 : {
607 : struct pt_regs *regs = current_pt_regs();
608 : struct sigframe __user *frame;
609 : sigset_t set;
610 :
611 : frame = (struct sigframe __user *)(regs->sp - 8);
612 :
613 : if (!access_ok(frame, sizeof(*frame)))
614 : goto badframe;
615 : if (__get_user(set.sig[0], &frame->sc.oldmask) ||
616 : __get_user(set.sig[1], &frame->extramask[0]))
617 : goto badframe;
618 :
619 : set_current_blocked(&set);
620 :
621 : /*
622 : * x86_32 has no uc_flags bits relevant to restore_sigcontext.
623 : * Save a few cycles by skipping the __get_user.
624 : */
625 : if (restore_sigcontext(regs, &frame->sc, 0))
626 : goto badframe;
627 : return regs->ax;
628 :
629 : badframe:
630 : signal_fault(regs, frame, "sigreturn");
631 :
632 : return 0;
633 : }
634 : #endif /* CONFIG_X86_32 */
635 :
636 1265 : SYSCALL_DEFINE0(rt_sigreturn)
637 : {
638 1265 : struct pt_regs *regs = current_pt_regs();
639 1265 : struct rt_sigframe __user *frame;
640 1265 : sigset_t set;
641 1265 : unsigned long uc_flags;
642 :
643 1265 : frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
644 1265 : if (!access_ok(frame, sizeof(*frame)))
645 0 : goto badframe;
646 1265 : if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
647 0 : goto badframe;
648 1265 : if (__get_user(uc_flags, &frame->uc.uc_flags))
649 0 : goto badframe;
650 :
651 1265 : set_current_blocked(&set);
652 :
653 1265 : if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
654 0 : goto badframe;
655 :
656 1265 : if (restore_altstack(&frame->uc.uc_stack))
657 0 : goto badframe;
658 :
659 1265 : return regs->ax;
660 :
661 0 : badframe:
662 0 : signal_fault(regs, frame, "rt_sigreturn");
663 0 : return 0;
664 : }
665 :
666 1265 : static inline int is_ia32_compat_frame(struct ksignal *ksig)
667 : {
668 1265 : return IS_ENABLED(CONFIG_IA32_EMULATION) &&
669 1265 : ksig->ka.sa.sa_flags & SA_IA32_ABI;
670 : }
671 :
672 1265 : static inline int is_ia32_frame(struct ksignal *ksig)
673 : {
674 1265 : return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
675 : }
676 :
677 1265 : static inline int is_x32_frame(struct ksignal *ksig)
678 : {
679 1265 : return IS_ENABLED(CONFIG_X86_X32_ABI) &&
680 : ksig->ka.sa.sa_flags & SA_X32_ABI;
681 : }
682 :
683 : static int
684 1265 : setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
685 : {
686 1265 : int usig = ksig->sig;
687 1265 : sigset_t *set = sigmask_to_save();
688 1265 : compat_sigset_t *cset = (compat_sigset_t *) set;
689 :
690 : /* Perform fixup for the pre-signal frame. */
691 1265 : rseq_signal_deliver(ksig, regs);
692 :
693 : /* Set up the stack frame */
694 1265 : if (is_ia32_frame(ksig)) {
695 0 : if (ksig->ka.sa.sa_flags & SA_SIGINFO)
696 0 : return ia32_setup_rt_frame(usig, ksig, cset, regs);
697 : else
698 0 : return ia32_setup_frame(usig, ksig, cset, regs);
699 1265 : } else if (is_x32_frame(ksig)) {
700 : return x32_setup_rt_frame(ksig, cset, regs);
701 : } else {
702 1265 : return __setup_rt_frame(ksig->sig, ksig, set, regs);
703 : }
704 : }
705 :
706 : static void
707 1265 : handle_signal(struct ksignal *ksig, struct pt_regs *regs)
708 : {
709 1265 : bool stepping, failed;
710 1265 : struct fpu *fpu = ¤t->thread.fpu;
711 :
712 1265 : if (v8086_mode(regs))
713 1265 : save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
714 :
715 : /* Are we from a system call? */
716 1265 : if (syscall_get_nr(current, regs) >= 0) {
717 : /* If so, check system call restarting.. */
718 2530 : switch (syscall_get_error(current, regs)) {
719 8 : case -ERESTART_RESTARTBLOCK:
720 : case -ERESTARTNOHAND:
721 8 : regs->ax = -EINTR;
722 8 : break;
723 :
724 0 : case -ERESTARTSYS:
725 0 : if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
726 0 : regs->ax = -EINTR;
727 0 : break;
728 : }
729 0 : fallthrough;
730 : case -ERESTARTNOINTR:
731 0 : regs->ax = regs->orig_ax;
732 0 : regs->ip -= 2;
733 0 : break;
734 : }
735 0 : }
736 :
737 : /*
738 : * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
739 : * so that register information in the sigcontext is correct and
740 : * then notify the tracer before entering the signal handler.
741 : */
742 1265 : stepping = test_thread_flag(TIF_SINGLESTEP);
743 1265 : if (stepping)
744 0 : user_disable_single_step(current);
745 :
746 1265 : failed = (setup_rt_frame(ksig, regs) < 0);
747 1265 : if (!failed) {
748 : /*
749 : * Clear the direction flag as per the ABI for function entry.
750 : *
751 : * Clear RF when entering the signal handler, because
752 : * it might disable possible debug exception from the
753 : * signal handler.
754 : *
755 : * Clear TF for the case when it wasn't set by debugger to
756 : * avoid the recursive send_sigtrap() in SIGTRAP handler.
757 : */
758 1265 : regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
759 : /*
760 : * Ensure the signal handler starts with the new fpu state.
761 : */
762 1265 : fpu__clear_user_states(fpu);
763 : }
764 1265 : signal_setup_done(failed, ksig, stepping);
765 1265 : }
766 :
767 0 : static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
768 : {
769 : /*
770 : * This function is fundamentally broken as currently
771 : * implemented.
772 : *
773 : * The idea is that we want to trigger a call to the
774 : * restart_block() syscall and that we want in_ia32_syscall(),
775 : * in_x32_syscall(), etc. to match whatever they were in the
776 : * syscall being restarted. We assume that the syscall
777 : * instruction at (regs->ip - 2) matches whatever syscall
778 : * instruction we used to enter in the first place.
779 : *
780 : * The problem is that we can get here when ptrace pokes
781 : * syscall-like values into regs even if we're not in a syscall
782 : * at all.
783 : *
784 : * For now, we maintain historical behavior and guess based on
785 : * stored state. We could do better by saving the actual
786 : * syscall arch in restart_block or (with caveats on x32) by
787 : * checking if regs->ip points to 'int $0x80'. The current
788 : * behavior is incorrect if a tracer has a different bitness
789 : * than the tracee.
790 : */
791 : #ifdef CONFIG_IA32_EMULATION
792 0 : if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED))
793 0 : return __NR_ia32_restart_syscall;
794 : #endif
795 : #ifdef CONFIG_X86_X32_ABI
796 : return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
797 : #else
798 : return __NR_restart_syscall;
799 : #endif
800 : }
801 :
802 : /*
803 : * Note that 'init' is a special process: it doesn't get signals it doesn't
804 : * want to handle. Thus you cannot kill init even with a SIGKILL even by
805 : * mistake.
806 : */
807 1284 : void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
808 : {
809 1284 : struct ksignal ksig;
810 :
811 1284 : if (has_signal && get_signal(&ksig)) {
812 : /* Whee! Actually deliver the signal. */
813 1265 : handle_signal(&ksig, regs);
814 1265 : return;
815 : }
816 :
817 : /* Did we come from a system call? */
818 19 : if (syscall_get_nr(current, regs) >= 0) {
819 : /* Restart the system call - no handlers present */
820 38 : switch (syscall_get_error(current, regs)) {
821 8 : case -ERESTARTNOHAND:
822 : case -ERESTARTSYS:
823 : case -ERESTARTNOINTR:
824 8 : regs->ax = regs->orig_ax;
825 8 : regs->ip -= 2;
826 8 : break;
827 :
828 : case -ERESTART_RESTARTBLOCK:
829 0 : regs->ax = get_nr_restart_syscall(regs);
830 0 : regs->ip -= 2;
831 0 : break;
832 : }
833 0 : }
834 :
835 : /*
836 : * If there's no signal to deliver, we just put the saved sigmask
837 : * back.
838 : */
839 19 : restore_saved_sigmask();
840 : }
841 :
842 0 : void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
843 : {
844 0 : struct task_struct *me = current;
845 :
846 0 : if (show_unhandled_signals && printk_ratelimit()) {
847 0 : printk("%s"
848 : "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
849 0 : task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
850 0 : me->comm, me->pid, where, frame,
851 : regs->ip, regs->sp, regs->orig_ax);
852 0 : print_vma_addr(KERN_CONT " in ", regs->ip);
853 0 : pr_cont("\n");
854 : }
855 :
856 0 : force_sig(SIGSEGV);
857 0 : }
858 :
859 : #ifdef CONFIG_X86_X32_ABI
860 : COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
861 : {
862 : struct pt_regs *regs = current_pt_regs();
863 : struct rt_sigframe_x32 __user *frame;
864 : sigset_t set;
865 : unsigned long uc_flags;
866 :
867 : frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
868 :
869 : if (!access_ok(frame, sizeof(*frame)))
870 : goto badframe;
871 : if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
872 : goto badframe;
873 : if (__get_user(uc_flags, &frame->uc.uc_flags))
874 : goto badframe;
875 :
876 : set_current_blocked(&set);
877 :
878 : if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
879 : goto badframe;
880 :
881 : if (compat_restore_altstack(&frame->uc.uc_stack))
882 : goto badframe;
883 :
884 : return regs->ax;
885 :
886 : badframe:
887 : signal_fault(regs, frame, "x32 rt_sigreturn");
888 : return 0;
889 : }
890 : #endif
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