1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs 5 * 6 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 7 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes 8 * 2000-2002 x86-64 support by Andi Kleen 9 */ 10 11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 12 13 #include <linux/sched.h> 14 #include <linux/sched/task_stack.h> 15 #include <linux/mm.h> 16 #include <linux/smp.h> 17 #include <linux/kernel.h> 18 #include <linux/errno.h> 19 #include <linux/wait.h> 20 #include <linux/tracehook.h> 21 #include <linux/unistd.h> 22 #include <linux/stddef.h> 23 #include <linux/personality.h> 24 #include <linux/uaccess.h> 25 #include <linux/user-return-notifier.h> 26 #include <linux/uprobes.h> 27 #include <linux/context_tracking.h> 28 #include <linux/syscalls.h> 29 30 #include <asm/processor.h> 31 #include <asm/ucontext.h> 32 #include <asm/fpu/internal.h> 33 #include <asm/fpu/signal.h> 34 #include <asm/vdso.h> 35 #include <asm/mce.h> 36 #include <asm/sighandling.h> 37 #include <asm/vm86.h> 38 39 #ifdef CONFIG_X86_64 40 #include <asm/proto.h> 41 #include <asm/ia32_unistd.h> 42 #endif /* CONFIG_X86_64 */ 43 44 #include <asm/syscall.h> 45 #include <asm/syscalls.h> 46 47 #include <asm/sigframe.h> 48 #include <asm/signal.h> 49 50 #define COPY(x) do { \ 51 get_user_ex(regs->x, &sc->x); \ 52 } while (0) 53 54 #define GET_SEG(seg) ({ \ 55 unsigned short tmp; \ 56 get_user_ex(tmp, &sc->seg); \ 57 tmp; \ 58 }) 59 60 #define COPY_SEG(seg) do { \ 61 regs->seg = GET_SEG(seg); \ 62 } while (0) 63 64 #define COPY_SEG_CPL3(seg) do { \ 65 regs->seg = GET_SEG(seg) | 3; \ 66 } while (0) 67 68 #ifdef CONFIG_X86_64 69 /* 70 * If regs->ss will cause an IRET fault, change it. Otherwise leave it 71 * alone. Using this generally makes no sense unless 72 * user_64bit_mode(regs) would return true. 73 */ 74 static void force_valid_ss(struct pt_regs *regs) 75 { 76 u32 ar; 77 asm volatile ("lar %[old_ss], %[ar]\n\t" 78 "jz 1f\n\t" /* If invalid: */ 79 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */ 80 "1:" 81 : [ar] "=r" (ar) 82 : [old_ss] "rm" ((u16)regs->ss)); 83 84 /* 85 * For a valid 64-bit user context, we need DPL 3, type 86 * read-write data or read-write exp-down data, and S and P 87 * set. We can't use VERW because VERW doesn't check the 88 * P bit. 89 */ 90 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK; 91 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) && 92 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN)) 93 regs->ss = __USER_DS; 94 } 95 #endif 96 97 static int restore_sigcontext(struct pt_regs *regs, 98 struct sigcontext __user *sc, 99 unsigned long uc_flags) 100 { 101 unsigned long buf_val; 102 void __user *buf; 103 unsigned int tmpflags; 104 unsigned int err = 0; 105 106 /* Always make any pending restarted system calls return -EINTR */ 107 current->restart_block.fn = do_no_restart_syscall; 108 109 get_user_try { 110 111 #ifdef CONFIG_X86_32 112 set_user_gs(regs, GET_SEG(gs)); 113 COPY_SEG(fs); 114 COPY_SEG(es); 115 COPY_SEG(ds); 116 #endif /* CONFIG_X86_32 */ 117 118 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); 119 COPY(dx); COPY(cx); COPY(ip); COPY(ax); 120 121 #ifdef CONFIG_X86_64 122 COPY(r8); 123 COPY(r9); 124 COPY(r10); 125 COPY(r11); 126 COPY(r12); 127 COPY(r13); 128 COPY(r14); 129 COPY(r15); 130 #endif /* CONFIG_X86_64 */ 131 132 COPY_SEG_CPL3(cs); 133 COPY_SEG_CPL3(ss); 134 135 get_user_ex(tmpflags, &sc->flags); 136 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); 137 regs->orig_ax = -1; /* disable syscall checks */ 138 139 get_user_ex(buf_val, &sc->fpstate); 140 buf = (void __user *)buf_val; 141 } get_user_catch(err); 142 143 #ifdef CONFIG_X86_64 144 /* 145 * Fix up SS if needed for the benefit of old DOSEMU and 146 * CRIU. 147 */ 148 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs))) 149 force_valid_ss(regs); 150 #endif 151 152 err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32)); 153 154 force_iret(); 155 156 return err; 157 } 158 159 int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate, 160 struct pt_regs *regs, unsigned long mask) 161 { 162 int err = 0; 163 164 put_user_try { 165 166 #ifdef CONFIG_X86_32 167 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs); 168 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs); 169 put_user_ex(regs->es, (unsigned int __user *)&sc->es); 170 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds); 171 #endif /* CONFIG_X86_32 */ 172 173 put_user_ex(regs->di, &sc->di); 174 put_user_ex(regs->si, &sc->si); 175 put_user_ex(regs->bp, &sc->bp); 176 put_user_ex(regs->sp, &sc->sp); 177 put_user_ex(regs->bx, &sc->bx); 178 put_user_ex(regs->dx, &sc->dx); 179 put_user_ex(regs->cx, &sc->cx); 180 put_user_ex(regs->ax, &sc->ax); 181 #ifdef CONFIG_X86_64 182 put_user_ex(regs->r8, &sc->r8); 183 put_user_ex(regs->r9, &sc->r9); 184 put_user_ex(regs->r10, &sc->r10); 185 put_user_ex(regs->r11, &sc->r11); 186 put_user_ex(regs->r12, &sc->r12); 187 put_user_ex(regs->r13, &sc->r13); 188 put_user_ex(regs->r14, &sc->r14); 189 put_user_ex(regs->r15, &sc->r15); 190 #endif /* CONFIG_X86_64 */ 191 192 put_user_ex(current->thread.trap_nr, &sc->trapno); 193 put_user_ex(current->thread.error_code, &sc->err); 194 put_user_ex(regs->ip, &sc->ip); 195 #ifdef CONFIG_X86_32 196 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs); 197 put_user_ex(regs->flags, &sc->flags); 198 put_user_ex(regs->sp, &sc->sp_at_signal); 199 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss); 200 #else /* !CONFIG_X86_32 */ 201 put_user_ex(regs->flags, &sc->flags); 202 put_user_ex(regs->cs, &sc->cs); 203 put_user_ex(0, &sc->gs); 204 put_user_ex(0, &sc->fs); 205 put_user_ex(regs->ss, &sc->ss); 206 #endif /* CONFIG_X86_32 */ 207 208 put_user_ex(fpstate, (unsigned long __user *)&sc->fpstate); 209 210 /* non-iBCS2 extensions.. */ 211 put_user_ex(mask, &sc->oldmask); 212 put_user_ex(current->thread.cr2, &sc->cr2); 213 } put_user_catch(err); 214 215 return err; 216 } 217 218 /* 219 * Set up a signal frame. 220 */ 221 222 /* 223 * Determine which stack to use.. 224 */ 225 static unsigned long align_sigframe(unsigned long sp) 226 { 227 #ifdef CONFIG_X86_32 228 /* 229 * Align the stack pointer according to the i386 ABI, 230 * i.e. so that on function entry ((sp + 4) & 15) == 0. 231 */ 232 sp = ((sp + 4) & -16ul) - 4; 233 #else /* !CONFIG_X86_32 */ 234 sp = round_down(sp, 16) - 8; 235 #endif 236 return sp; 237 } 238 239 static void __user * 240 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, 241 void __user **fpstate) 242 { 243 /* Default to using normal stack */ 244 unsigned long math_size = 0; 245 unsigned long sp = regs->sp; 246 unsigned long buf_fx = 0; 247 int onsigstack = on_sig_stack(sp); 248 int ret; 249 250 /* redzone */ 251 if (IS_ENABLED(CONFIG_X86_64)) 252 sp -= 128; 253 254 /* This is the X/Open sanctioned signal stack switching. */ 255 if (ka->sa.sa_flags & SA_ONSTACK) { 256 if (sas_ss_flags(sp) == 0) 257 sp = current->sas_ss_sp + current->sas_ss_size; 258 } else if (IS_ENABLED(CONFIG_X86_32) && 259 !onsigstack && 260 regs->ss != __USER_DS && 261 !(ka->sa.sa_flags & SA_RESTORER) && 262 ka->sa.sa_restorer) { 263 /* This is the legacy signal stack switching. */ 264 sp = (unsigned long) ka->sa.sa_restorer; 265 } 266 267 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32), 268 &buf_fx, &math_size); 269 *fpstate = (void __user *)sp; 270 271 sp = align_sigframe(sp - frame_size); 272 273 /* 274 * If we are on the alternate signal stack and would overflow it, don't. 275 * Return an always-bogus address instead so we will die with SIGSEGV. 276 */ 277 if (onsigstack && !likely(on_sig_stack(sp))) 278 return (void __user *)-1L; 279 280 /* save i387 and extended state */ 281 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size); 282 if (ret < 0) 283 return (void __user *)-1L; 284 285 return (void __user *)sp; 286 } 287 288 #ifdef CONFIG_X86_32 289 static const struct { 290 u16 poplmovl; 291 u32 val; 292 u16 int80; 293 } __attribute__((packed)) retcode = { 294 0xb858, /* popl %eax; movl $..., %eax */ 295 __NR_sigreturn, 296 0x80cd, /* int $0x80 */ 297 }; 298 299 static const struct { 300 u8 movl; 301 u32 val; 302 u16 int80; 303 u8 pad; 304 } __attribute__((packed)) rt_retcode = { 305 0xb8, /* movl $..., %eax */ 306 __NR_rt_sigreturn, 307 0x80cd, /* int $0x80 */ 308 0 309 }; 310 311 static int 312 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, 313 struct pt_regs *regs) 314 { 315 struct sigframe __user *frame; 316 void __user *restorer; 317 int err = 0; 318 void __user *fpstate = NULL; 319 320 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); 321 322 if (!access_ok(frame, sizeof(*frame))) 323 return -EFAULT; 324 325 if (__put_user(sig, &frame->sig)) 326 return -EFAULT; 327 328 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0])) 329 return -EFAULT; 330 331 if (_NSIG_WORDS > 1) { 332 if (__copy_to_user(&frame->extramask, &set->sig[1], 333 sizeof(frame->extramask))) 334 return -EFAULT; 335 } 336 337 if (current->mm->context.vdso) 338 restorer = current->mm->context.vdso + 339 vdso_image_32.sym___kernel_sigreturn; 340 else 341 restorer = &frame->retcode; 342 if (ksig->ka.sa.sa_flags & SA_RESTORER) 343 restorer = ksig->ka.sa.sa_restorer; 344 345 /* Set up to return from userspace. */ 346 err |= __put_user(restorer, &frame->pretcode); 347 348 /* 349 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80 350 * 351 * WE DO NOT USE IT ANY MORE! It's only left here for historical 352 * reasons and because gdb uses it as a signature to notice 353 * signal handler stack frames. 354 */ 355 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode); 356 357 if (err) 358 return -EFAULT; 359 360 /* Set up registers for signal handler */ 361 regs->sp = (unsigned long)frame; 362 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 363 regs->ax = (unsigned long)sig; 364 regs->dx = 0; 365 regs->cx = 0; 366 367 regs->ds = __USER_DS; 368 regs->es = __USER_DS; 369 regs->ss = __USER_DS; 370 regs->cs = __USER_CS; 371 372 return 0; 373 } 374 375 static int __setup_rt_frame(int sig, struct ksignal *ksig, 376 sigset_t *set, struct pt_regs *regs) 377 { 378 struct rt_sigframe __user *frame; 379 void __user *restorer; 380 int err = 0; 381 void __user *fpstate = NULL; 382 383 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); 384 385 if (!access_ok(frame, sizeof(*frame))) 386 return -EFAULT; 387 388 put_user_try { 389 put_user_ex(sig, &frame->sig); 390 put_user_ex(&frame->info, &frame->pinfo); 391 put_user_ex(&frame->uc, &frame->puc); 392 393 /* Create the ucontext. */ 394 if (boot_cpu_has(X86_FEATURE_XSAVE)) 395 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); 396 else 397 put_user_ex(0, &frame->uc.uc_flags); 398 put_user_ex(0, &frame->uc.uc_link); 399 save_altstack_ex(&frame->uc.uc_stack, regs->sp); 400 401 /* Set up to return from userspace. */ 402 restorer = current->mm->context.vdso + 403 vdso_image_32.sym___kernel_rt_sigreturn; 404 if (ksig->ka.sa.sa_flags & SA_RESTORER) 405 restorer = ksig->ka.sa.sa_restorer; 406 put_user_ex(restorer, &frame->pretcode); 407 408 /* 409 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 410 * 411 * WE DO NOT USE IT ANY MORE! It's only left here for historical 412 * reasons and because gdb uses it as a signature to notice 413 * signal handler stack frames. 414 */ 415 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode); 416 } put_user_catch(err); 417 418 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 419 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, 420 regs, set->sig[0]); 421 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 422 423 if (err) 424 return -EFAULT; 425 426 /* Set up registers for signal handler */ 427 regs->sp = (unsigned long)frame; 428 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 429 regs->ax = (unsigned long)sig; 430 regs->dx = (unsigned long)&frame->info; 431 regs->cx = (unsigned long)&frame->uc; 432 433 regs->ds = __USER_DS; 434 regs->es = __USER_DS; 435 regs->ss = __USER_DS; 436 regs->cs = __USER_CS; 437 438 return 0; 439 } 440 #else /* !CONFIG_X86_32 */ 441 static unsigned long frame_uc_flags(struct pt_regs *regs) 442 { 443 unsigned long flags; 444 445 if (boot_cpu_has(X86_FEATURE_XSAVE)) 446 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS; 447 else 448 flags = UC_SIGCONTEXT_SS; 449 450 if (likely(user_64bit_mode(regs))) 451 flags |= UC_STRICT_RESTORE_SS; 452 453 return flags; 454 } 455 456 static int __setup_rt_frame(int sig, struct ksignal *ksig, 457 sigset_t *set, struct pt_regs *regs) 458 { 459 struct rt_sigframe __user *frame; 460 void __user *fp = NULL; 461 unsigned long uc_flags; 462 int err = 0; 463 464 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); 465 466 if (!access_ok(frame, sizeof(*frame))) 467 return -EFAULT; 468 469 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 470 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 471 return -EFAULT; 472 } 473 474 uc_flags = frame_uc_flags(regs); 475 476 put_user_try { 477 /* Create the ucontext. */ 478 put_user_ex(uc_flags, &frame->uc.uc_flags); 479 put_user_ex(0, &frame->uc.uc_link); 480 save_altstack_ex(&frame->uc.uc_stack, regs->sp); 481 482 /* Set up to return from userspace. If provided, use a stub 483 already in userspace. */ 484 /* x86-64 should always use SA_RESTORER. */ 485 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 486 put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode); 487 } else { 488 /* could use a vstub here */ 489 err |= -EFAULT; 490 } 491 } put_user_catch(err); 492 493 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]); 494 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 495 496 if (err) 497 return -EFAULT; 498 499 /* Set up registers for signal handler */ 500 regs->di = sig; 501 /* In case the signal handler was declared without prototypes */ 502 regs->ax = 0; 503 504 /* This also works for non SA_SIGINFO handlers because they expect the 505 next argument after the signal number on the stack. */ 506 regs->si = (unsigned long)&frame->info; 507 regs->dx = (unsigned long)&frame->uc; 508 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 509 510 regs->sp = (unsigned long)frame; 511 512 /* 513 * Set up the CS and SS registers to run signal handlers in 514 * 64-bit mode, even if the handler happens to be interrupting 515 * 32-bit or 16-bit code. 516 * 517 * SS is subtle. In 64-bit mode, we don't need any particular 518 * SS descriptor, but we do need SS to be valid. It's possible 519 * that the old SS is entirely bogus -- this can happen if the 520 * signal we're trying to deliver is #GP or #SS caused by a bad 521 * SS value. We also have a compatbility issue here: DOSEMU 522 * relies on the contents of the SS register indicating the 523 * SS value at the time of the signal, even though that code in 524 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU 525 * avoids relying on sigreturn to restore SS; instead it uses 526 * a trampoline.) So we do our best: if the old SS was valid, 527 * we keep it. Otherwise we replace it. 528 */ 529 regs->cs = __USER_CS; 530 531 if (unlikely(regs->ss != __USER_DS)) 532 force_valid_ss(regs); 533 534 return 0; 535 } 536 #endif /* CONFIG_X86_32 */ 537 538 static int x32_setup_rt_frame(struct ksignal *ksig, 539 compat_sigset_t *set, 540 struct pt_regs *regs) 541 { 542 #ifdef CONFIG_X86_X32_ABI 543 struct rt_sigframe_x32 __user *frame; 544 unsigned long uc_flags; 545 void __user *restorer; 546 int err = 0; 547 void __user *fpstate = NULL; 548 549 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); 550 551 if (!access_ok(frame, sizeof(*frame))) 552 return -EFAULT; 553 554 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 555 if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true)) 556 return -EFAULT; 557 } 558 559 uc_flags = frame_uc_flags(regs); 560 561 put_user_try { 562 /* Create the ucontext. */ 563 put_user_ex(uc_flags, &frame->uc.uc_flags); 564 put_user_ex(0, &frame->uc.uc_link); 565 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp); 566 put_user_ex(0, &frame->uc.uc__pad0); 567 568 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 569 restorer = ksig->ka.sa.sa_restorer; 570 } else { 571 /* could use a vstub here */ 572 restorer = NULL; 573 err |= -EFAULT; 574 } 575 put_user_ex(restorer, (unsigned long __user *)&frame->pretcode); 576 } put_user_catch(err); 577 578 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, 579 regs, set->sig[0]); 580 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 581 582 if (err) 583 return -EFAULT; 584 585 /* Set up registers for signal handler */ 586 regs->sp = (unsigned long) frame; 587 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 588 589 /* We use the x32 calling convention here... */ 590 regs->di = ksig->sig; 591 regs->si = (unsigned long) &frame->info; 592 regs->dx = (unsigned long) &frame->uc; 593 594 loadsegment(ds, __USER_DS); 595 loadsegment(es, __USER_DS); 596 597 regs->cs = __USER_CS; 598 regs->ss = __USER_DS; 599 #endif /* CONFIG_X86_X32_ABI */ 600 601 return 0; 602 } 603 604 /* 605 * Do a signal return; undo the signal stack. 606 */ 607 #ifdef CONFIG_X86_32 608 SYSCALL_DEFINE0(sigreturn) 609 { 610 struct pt_regs *regs = current_pt_regs(); 611 struct sigframe __user *frame; 612 sigset_t set; 613 614 frame = (struct sigframe __user *)(regs->sp - 8); 615 616 if (!access_ok(frame, sizeof(*frame))) 617 goto badframe; 618 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1 619 && __copy_from_user(&set.sig[1], &frame->extramask, 620 sizeof(frame->extramask)))) 621 goto badframe; 622 623 set_current_blocked(&set); 624 625 /* 626 * x86_32 has no uc_flags bits relevant to restore_sigcontext. 627 * Save a few cycles by skipping the __get_user. 628 */ 629 if (restore_sigcontext(regs, &frame->sc, 0)) 630 goto badframe; 631 return regs->ax; 632 633 badframe: 634 signal_fault(regs, frame, "sigreturn"); 635 636 return 0; 637 } 638 #endif /* CONFIG_X86_32 */ 639 640 SYSCALL_DEFINE0(rt_sigreturn) 641 { 642 struct pt_regs *regs = current_pt_regs(); 643 struct rt_sigframe __user *frame; 644 sigset_t set; 645 unsigned long uc_flags; 646 647 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 648 if (!access_ok(frame, sizeof(*frame))) 649 goto badframe; 650 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 651 goto badframe; 652 if (__get_user(uc_flags, &frame->uc.uc_flags)) 653 goto badframe; 654 655 set_current_blocked(&set); 656 657 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 658 goto badframe; 659 660 if (restore_altstack(&frame->uc.uc_stack)) 661 goto badframe; 662 663 return regs->ax; 664 665 badframe: 666 signal_fault(regs, frame, "rt_sigreturn"); 667 return 0; 668 } 669 670 static inline int is_ia32_compat_frame(struct ksignal *ksig) 671 { 672 return IS_ENABLED(CONFIG_IA32_EMULATION) && 673 ksig->ka.sa.sa_flags & SA_IA32_ABI; 674 } 675 676 static inline int is_ia32_frame(struct ksignal *ksig) 677 { 678 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); 679 } 680 681 static inline int is_x32_frame(struct ksignal *ksig) 682 { 683 return IS_ENABLED(CONFIG_X86_X32_ABI) && 684 ksig->ka.sa.sa_flags & SA_X32_ABI; 685 } 686 687 static int 688 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 689 { 690 int usig = ksig->sig; 691 sigset_t *set = sigmask_to_save(); 692 compat_sigset_t *cset = (compat_sigset_t *) set; 693 694 /* Perform fixup for the pre-signal frame. */ 695 rseq_signal_deliver(ksig, regs); 696 697 /* Set up the stack frame */ 698 if (is_ia32_frame(ksig)) { 699 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 700 return ia32_setup_rt_frame(usig, ksig, cset, regs); 701 else 702 return ia32_setup_frame(usig, ksig, cset, regs); 703 } else if (is_x32_frame(ksig)) { 704 return x32_setup_rt_frame(ksig, cset, regs); 705 } else { 706 return __setup_rt_frame(ksig->sig, ksig, set, regs); 707 } 708 } 709 710 static void 711 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 712 { 713 bool stepping, failed; 714 struct fpu *fpu = ¤t->thread.fpu; 715 716 if (v8086_mode(regs)) 717 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); 718 719 /* Are we from a system call? */ 720 if (syscall_get_nr(current, regs) >= 0) { 721 /* If so, check system call restarting.. */ 722 switch (syscall_get_error(current, regs)) { 723 case -ERESTART_RESTARTBLOCK: 724 case -ERESTARTNOHAND: 725 regs->ax = -EINTR; 726 break; 727 728 case -ERESTARTSYS: 729 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 730 regs->ax = -EINTR; 731 break; 732 } 733 /* fallthrough */ 734 case -ERESTARTNOINTR: 735 regs->ax = regs->orig_ax; 736 regs->ip -= 2; 737 break; 738 } 739 } 740 741 /* 742 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now 743 * so that register information in the sigcontext is correct and 744 * then notify the tracer before entering the signal handler. 745 */ 746 stepping = test_thread_flag(TIF_SINGLESTEP); 747 if (stepping) 748 user_disable_single_step(current); 749 750 failed = (setup_rt_frame(ksig, regs) < 0); 751 if (!failed) { 752 /* 753 * Clear the direction flag as per the ABI for function entry. 754 * 755 * Clear RF when entering the signal handler, because 756 * it might disable possible debug exception from the 757 * signal handler. 758 * 759 * Clear TF for the case when it wasn't set by debugger to 760 * avoid the recursive send_sigtrap() in SIGTRAP handler. 761 */ 762 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); 763 /* 764 * Ensure the signal handler starts with the new fpu state. 765 */ 766 fpu__clear(fpu); 767 } 768 signal_setup_done(failed, ksig, stepping); 769 } 770 771 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) 772 { 773 /* 774 * This function is fundamentally broken as currently 775 * implemented. 776 * 777 * The idea is that we want to trigger a call to the 778 * restart_block() syscall and that we want in_ia32_syscall(), 779 * in_x32_syscall(), etc. to match whatever they were in the 780 * syscall being restarted. We assume that the syscall 781 * instruction at (regs->ip - 2) matches whatever syscall 782 * instruction we used to enter in the first place. 783 * 784 * The problem is that we can get here when ptrace pokes 785 * syscall-like values into regs even if we're not in a syscall 786 * at all. 787 * 788 * For now, we maintain historical behavior and guess based on 789 * stored state. We could do better by saving the actual 790 * syscall arch in restart_block or (with caveats on x32) by 791 * checking if regs->ip points to 'int $0x80'. The current 792 * behavior is incorrect if a tracer has a different bitness 793 * than the tracee. 794 */ 795 #ifdef CONFIG_IA32_EMULATION 796 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED)) 797 return __NR_ia32_restart_syscall; 798 #endif 799 #ifdef CONFIG_X86_X32_ABI 800 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); 801 #else 802 return __NR_restart_syscall; 803 #endif 804 } 805 806 /* 807 * Note that 'init' is a special process: it doesn't get signals it doesn't 808 * want to handle. Thus you cannot kill init even with a SIGKILL even by 809 * mistake. 810 */ 811 void do_signal(struct pt_regs *regs) 812 { 813 struct ksignal ksig; 814 815 if (get_signal(&ksig)) { 816 /* Whee! Actually deliver the signal. */ 817 handle_signal(&ksig, regs); 818 return; 819 } 820 821 /* Did we come from a system call? */ 822 if (syscall_get_nr(current, regs) >= 0) { 823 /* Restart the system call - no handlers present */ 824 switch (syscall_get_error(current, regs)) { 825 case -ERESTARTNOHAND: 826 case -ERESTARTSYS: 827 case -ERESTARTNOINTR: 828 regs->ax = regs->orig_ax; 829 regs->ip -= 2; 830 break; 831 832 case -ERESTART_RESTARTBLOCK: 833 regs->ax = get_nr_restart_syscall(regs); 834 regs->ip -= 2; 835 break; 836 } 837 } 838 839 /* 840 * If there's no signal to deliver, we just put the saved sigmask 841 * back. 842 */ 843 restore_saved_sigmask(); 844 } 845 846 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 847 { 848 struct task_struct *me = current; 849 850 if (show_unhandled_signals && printk_ratelimit()) { 851 printk("%s" 852 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 853 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, 854 me->comm, me->pid, where, frame, 855 regs->ip, regs->sp, regs->orig_ax); 856 print_vma_addr(KERN_CONT " in ", regs->ip); 857 pr_cont("\n"); 858 } 859 860 force_sig(SIGSEGV, me); 861 } 862 863 #ifdef CONFIG_X86_X32_ABI 864 asmlinkage long sys32_x32_rt_sigreturn(void) 865 { 866 struct pt_regs *regs = current_pt_regs(); 867 struct rt_sigframe_x32 __user *frame; 868 sigset_t set; 869 unsigned long uc_flags; 870 871 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); 872 873 if (!access_ok(frame, sizeof(*frame))) 874 goto badframe; 875 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 876 goto badframe; 877 if (__get_user(uc_flags, &frame->uc.uc_flags)) 878 goto badframe; 879 880 set_current_blocked(&set); 881 882 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 883 goto badframe; 884 885 if (compat_restore_altstack(&frame->uc.uc_stack)) 886 goto badframe; 887 888 return regs->ax; 889 890 badframe: 891 signal_fault(regs, frame, "x32 rt_sigreturn"); 892 return 0; 893 } 894 #endif 895