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, &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 struct fpu *fpu = ¤t->thread.fpu; 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 if (fpu->initialized) { 268 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32), 269 &buf_fx, &math_size); 270 *fpstate = (void __user *)sp; 271 } 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 (onsigstack && !likely(on_sig_stack(sp))) 280 return (void __user *)-1L; 281 282 /* save i387 and extended state */ 283 if (fpu->initialized && 284 copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0) 285 return (void __user *)-1L; 286 287 return (void __user *)sp; 288 } 289 290 #ifdef CONFIG_X86_32 291 static const struct { 292 u16 poplmovl; 293 u32 val; 294 u16 int80; 295 } __attribute__((packed)) retcode = { 296 0xb858, /* popl %eax; movl $..., %eax */ 297 __NR_sigreturn, 298 0x80cd, /* int $0x80 */ 299 }; 300 301 static const struct { 302 u8 movl; 303 u32 val; 304 u16 int80; 305 u8 pad; 306 } __attribute__((packed)) rt_retcode = { 307 0xb8, /* movl $..., %eax */ 308 __NR_rt_sigreturn, 309 0x80cd, /* int $0x80 */ 310 0 311 }; 312 313 static int 314 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, 315 struct pt_regs *regs) 316 { 317 struct sigframe __user *frame; 318 void __user *restorer; 319 int err = 0; 320 void __user *fpstate = NULL; 321 322 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); 323 324 if (!access_ok(frame, sizeof(*frame))) 325 return -EFAULT; 326 327 if (__put_user(sig, &frame->sig)) 328 return -EFAULT; 329 330 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0])) 331 return -EFAULT; 332 333 if (_NSIG_WORDS > 1) { 334 if (__copy_to_user(&frame->extramask, &set->sig[1], 335 sizeof(frame->extramask))) 336 return -EFAULT; 337 } 338 339 if (current->mm->context.vdso) 340 restorer = current->mm->context.vdso + 341 vdso_image_32.sym___kernel_sigreturn; 342 else 343 restorer = &frame->retcode; 344 if (ksig->ka.sa.sa_flags & SA_RESTORER) 345 restorer = ksig->ka.sa.sa_restorer; 346 347 /* Set up to return from userspace. */ 348 err |= __put_user(restorer, &frame->pretcode); 349 350 /* 351 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80 352 * 353 * WE DO NOT USE IT ANY MORE! It's only left here for historical 354 * reasons and because gdb uses it as a signature to notice 355 * signal handler stack frames. 356 */ 357 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode); 358 359 if (err) 360 return -EFAULT; 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 } 376 377 static int __setup_rt_frame(int sig, struct ksignal *ksig, 378 sigset_t *set, struct pt_regs *regs) 379 { 380 struct rt_sigframe __user *frame; 381 void __user *restorer; 382 int err = 0; 383 void __user *fpstate = NULL; 384 385 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); 386 387 if (!access_ok(frame, sizeof(*frame))) 388 return -EFAULT; 389 390 put_user_try { 391 put_user_ex(sig, &frame->sig); 392 put_user_ex(&frame->info, &frame->pinfo); 393 put_user_ex(&frame->uc, &frame->puc); 394 395 /* Create the ucontext. */ 396 if (boot_cpu_has(X86_FEATURE_XSAVE)) 397 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); 398 else 399 put_user_ex(0, &frame->uc.uc_flags); 400 put_user_ex(0, &frame->uc.uc_link); 401 save_altstack_ex(&frame->uc.uc_stack, regs->sp); 402 403 /* Set up to return from userspace. */ 404 restorer = current->mm->context.vdso + 405 vdso_image_32.sym___kernel_rt_sigreturn; 406 if (ksig->ka.sa.sa_flags & SA_RESTORER) 407 restorer = ksig->ka.sa.sa_restorer; 408 put_user_ex(restorer, &frame->pretcode); 409 410 /* 411 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 412 * 413 * WE DO NOT USE IT ANY MORE! It's only left here for historical 414 * reasons and because gdb uses it as a signature to notice 415 * signal handler stack frames. 416 */ 417 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode); 418 } put_user_catch(err); 419 420 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 421 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, 422 regs, set->sig[0]); 423 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 424 425 if (err) 426 return -EFAULT; 427 428 /* Set up registers for signal handler */ 429 regs->sp = (unsigned long)frame; 430 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 431 regs->ax = (unsigned long)sig; 432 regs->dx = (unsigned long)&frame->info; 433 regs->cx = (unsigned long)&frame->uc; 434 435 regs->ds = __USER_DS; 436 regs->es = __USER_DS; 437 regs->ss = __USER_DS; 438 regs->cs = __USER_CS; 439 440 return 0; 441 } 442 #else /* !CONFIG_X86_32 */ 443 static unsigned long frame_uc_flags(struct pt_regs *regs) 444 { 445 unsigned long flags; 446 447 if (boot_cpu_has(X86_FEATURE_XSAVE)) 448 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS; 449 else 450 flags = UC_SIGCONTEXT_SS; 451 452 if (likely(user_64bit_mode(regs))) 453 flags |= UC_STRICT_RESTORE_SS; 454 455 return flags; 456 } 457 458 static int __setup_rt_frame(int sig, struct ksignal *ksig, 459 sigset_t *set, struct pt_regs *regs) 460 { 461 struct rt_sigframe __user *frame; 462 void __user *fp = NULL; 463 unsigned long uc_flags; 464 int err = 0; 465 466 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); 467 468 if (!access_ok(frame, sizeof(*frame))) 469 return -EFAULT; 470 471 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 472 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 473 return -EFAULT; 474 } 475 476 uc_flags = frame_uc_flags(regs); 477 478 put_user_try { 479 /* Create the ucontext. */ 480 put_user_ex(uc_flags, &frame->uc.uc_flags); 481 put_user_ex(0, &frame->uc.uc_link); 482 save_altstack_ex(&frame->uc.uc_stack, regs->sp); 483 484 /* Set up to return from userspace. If provided, use a stub 485 already in userspace. */ 486 /* x86-64 should always use SA_RESTORER. */ 487 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 488 put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode); 489 } else { 490 /* could use a vstub here */ 491 err |= -EFAULT; 492 } 493 } put_user_catch(err); 494 495 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]); 496 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 497 498 if (err) 499 return -EFAULT; 500 501 /* Set up registers for signal handler */ 502 regs->di = sig; 503 /* In case the signal handler was declared without prototypes */ 504 regs->ax = 0; 505 506 /* This also works for non SA_SIGINFO handlers because they expect the 507 next argument after the signal number on the stack. */ 508 regs->si = (unsigned long)&frame->info; 509 regs->dx = (unsigned long)&frame->uc; 510 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 511 512 regs->sp = (unsigned long)frame; 513 514 /* 515 * Set up the CS and SS registers to run signal handlers in 516 * 64-bit mode, even if the handler happens to be interrupting 517 * 32-bit or 16-bit code. 518 * 519 * SS is subtle. In 64-bit mode, we don't need any particular 520 * SS descriptor, but we do need SS to be valid. It's possible 521 * that the old SS is entirely bogus -- this can happen if the 522 * signal we're trying to deliver is #GP or #SS caused by a bad 523 * SS value. We also have a compatbility issue here: DOSEMU 524 * relies on the contents of the SS register indicating the 525 * SS value at the time of the signal, even though that code in 526 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU 527 * avoids relying on sigreturn to restore SS; instead it uses 528 * a trampoline.) So we do our best: if the old SS was valid, 529 * we keep it. Otherwise we replace it. 530 */ 531 regs->cs = __USER_CS; 532 533 if (unlikely(regs->ss != __USER_DS)) 534 force_valid_ss(regs); 535 536 return 0; 537 } 538 #endif /* CONFIG_X86_32 */ 539 540 static int x32_setup_rt_frame(struct ksignal *ksig, 541 compat_sigset_t *set, 542 struct pt_regs *regs) 543 { 544 #ifdef CONFIG_X86_X32_ABI 545 struct rt_sigframe_x32 __user *frame; 546 unsigned long uc_flags; 547 void __user *restorer; 548 int err = 0; 549 void __user *fpstate = NULL; 550 551 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); 552 553 if (!access_ok(frame, sizeof(*frame))) 554 return -EFAULT; 555 556 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 557 if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true)) 558 return -EFAULT; 559 } 560 561 uc_flags = frame_uc_flags(regs); 562 563 put_user_try { 564 /* Create the ucontext. */ 565 put_user_ex(uc_flags, &frame->uc.uc_flags); 566 put_user_ex(0, &frame->uc.uc_link); 567 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp); 568 put_user_ex(0, &frame->uc.uc__pad0); 569 570 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 571 restorer = ksig->ka.sa.sa_restorer; 572 } else { 573 /* could use a vstub here */ 574 restorer = NULL; 575 err |= -EFAULT; 576 } 577 put_user_ex(restorer, &frame->pretcode); 578 } put_user_catch(err); 579 580 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, 581 regs, set->sig[0]); 582 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 583 584 if (err) 585 return -EFAULT; 586 587 /* Set up registers for signal handler */ 588 regs->sp = (unsigned long) frame; 589 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 590 591 /* We use the x32 calling convention here... */ 592 regs->di = ksig->sig; 593 regs->si = (unsigned long) &frame->info; 594 regs->dx = (unsigned long) &frame->uc; 595 596 loadsegment(ds, __USER_DS); 597 loadsegment(es, __USER_DS); 598 599 regs->cs = __USER_CS; 600 regs->ss = __USER_DS; 601 #endif /* CONFIG_X86_X32_ABI */ 602 603 return 0; 604 } 605 606 /* 607 * Do a signal return; undo the signal stack. 608 */ 609 #ifdef CONFIG_X86_32 610 SYSCALL_DEFINE0(sigreturn) 611 { 612 struct pt_regs *regs = current_pt_regs(); 613 struct sigframe __user *frame; 614 sigset_t set; 615 616 frame = (struct sigframe __user *)(regs->sp - 8); 617 618 if (!access_ok(frame, sizeof(*frame))) 619 goto badframe; 620 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1 621 && __copy_from_user(&set.sig[1], &frame->extramask, 622 sizeof(frame->extramask)))) 623 goto badframe; 624 625 set_current_blocked(&set); 626 627 /* 628 * x86_32 has no uc_flags bits relevant to restore_sigcontext. 629 * Save a few cycles by skipping the __get_user. 630 */ 631 if (restore_sigcontext(regs, &frame->sc, 0)) 632 goto badframe; 633 return regs->ax; 634 635 badframe: 636 signal_fault(regs, frame, "sigreturn"); 637 638 return 0; 639 } 640 #endif /* CONFIG_X86_32 */ 641 642 SYSCALL_DEFINE0(rt_sigreturn) 643 { 644 struct pt_regs *regs = current_pt_regs(); 645 struct rt_sigframe __user *frame; 646 sigset_t set; 647 unsigned long uc_flags; 648 649 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 650 if (!access_ok(frame, sizeof(*frame))) 651 goto badframe; 652 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 653 goto badframe; 654 if (__get_user(uc_flags, &frame->uc.uc_flags)) 655 goto badframe; 656 657 set_current_blocked(&set); 658 659 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 660 goto badframe; 661 662 if (restore_altstack(&frame->uc.uc_stack)) 663 goto badframe; 664 665 return regs->ax; 666 667 badframe: 668 signal_fault(regs, frame, "rt_sigreturn"); 669 return 0; 670 } 671 672 static inline int is_ia32_compat_frame(struct ksignal *ksig) 673 { 674 return IS_ENABLED(CONFIG_IA32_EMULATION) && 675 ksig->ka.sa.sa_flags & SA_IA32_ABI; 676 } 677 678 static inline int is_ia32_frame(struct ksignal *ksig) 679 { 680 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); 681 } 682 683 static inline int is_x32_frame(struct ksignal *ksig) 684 { 685 return IS_ENABLED(CONFIG_X86_X32_ABI) && 686 ksig->ka.sa.sa_flags & SA_X32_ABI; 687 } 688 689 static int 690 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 691 { 692 int usig = ksig->sig; 693 sigset_t *set = sigmask_to_save(); 694 compat_sigset_t *cset = (compat_sigset_t *) set; 695 696 /* Perform fixup for the pre-signal frame. */ 697 rseq_signal_deliver(ksig, regs); 698 699 /* Set up the stack frame */ 700 if (is_ia32_frame(ksig)) { 701 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 702 return ia32_setup_rt_frame(usig, ksig, cset, regs); 703 else 704 return ia32_setup_frame(usig, ksig, cset, regs); 705 } else if (is_x32_frame(ksig)) { 706 return x32_setup_rt_frame(ksig, cset, regs); 707 } else { 708 return __setup_rt_frame(ksig->sig, ksig, set, regs); 709 } 710 } 711 712 static void 713 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 714 { 715 bool stepping, failed; 716 struct fpu *fpu = ¤t->thread.fpu; 717 718 if (v8086_mode(regs)) 719 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); 720 721 /* Are we from a system call? */ 722 if (syscall_get_nr(current, regs) >= 0) { 723 /* If so, check system call restarting.. */ 724 switch (syscall_get_error(current, regs)) { 725 case -ERESTART_RESTARTBLOCK: 726 case -ERESTARTNOHAND: 727 regs->ax = -EINTR; 728 break; 729 730 case -ERESTARTSYS: 731 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 732 regs->ax = -EINTR; 733 break; 734 } 735 /* fallthrough */ 736 case -ERESTARTNOINTR: 737 regs->ax = regs->orig_ax; 738 regs->ip -= 2; 739 break; 740 } 741 } 742 743 /* 744 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now 745 * so that register information in the sigcontext is correct and 746 * then notify the tracer before entering the signal handler. 747 */ 748 stepping = test_thread_flag(TIF_SINGLESTEP); 749 if (stepping) 750 user_disable_single_step(current); 751 752 failed = (setup_rt_frame(ksig, regs) < 0); 753 if (!failed) { 754 /* 755 * Clear the direction flag as per the ABI for function entry. 756 * 757 * Clear RF when entering the signal handler, because 758 * it might disable possible debug exception from the 759 * signal handler. 760 * 761 * Clear TF for the case when it wasn't set by debugger to 762 * avoid the recursive send_sigtrap() in SIGTRAP handler. 763 */ 764 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); 765 /* 766 * Ensure the signal handler starts with the new fpu state. 767 */ 768 if (fpu->initialized) 769 fpu__clear(fpu); 770 } 771 signal_setup_done(failed, ksig, stepping); 772 } 773 774 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) 775 { 776 /* 777 * This function is fundamentally broken as currently 778 * implemented. 779 * 780 * The idea is that we want to trigger a call to the 781 * restart_block() syscall and that we want in_ia32_syscall(), 782 * in_x32_syscall(), etc. to match whatever they were in the 783 * syscall being restarted. We assume that the syscall 784 * instruction at (regs->ip - 2) matches whatever syscall 785 * instruction we used to enter in the first place. 786 * 787 * The problem is that we can get here when ptrace pokes 788 * syscall-like values into regs even if we're not in a syscall 789 * at all. 790 * 791 * For now, we maintain historical behavior and guess based on 792 * stored state. We could do better by saving the actual 793 * syscall arch in restart_block or (with caveats on x32) by 794 * checking if regs->ip points to 'int $0x80'. The current 795 * behavior is incorrect if a tracer has a different bitness 796 * than the tracee. 797 */ 798 #ifdef CONFIG_IA32_EMULATION 799 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED)) 800 return __NR_ia32_restart_syscall; 801 #endif 802 #ifdef CONFIG_X86_X32_ABI 803 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); 804 #else 805 return __NR_restart_syscall; 806 #endif 807 } 808 809 /* 810 * Note that 'init' is a special process: it doesn't get signals it doesn't 811 * want to handle. Thus you cannot kill init even with a SIGKILL even by 812 * mistake. 813 */ 814 void do_signal(struct pt_regs *regs) 815 { 816 struct ksignal ksig; 817 818 if (get_signal(&ksig)) { 819 /* Whee! Actually deliver the signal. */ 820 handle_signal(&ksig, regs); 821 return; 822 } 823 824 /* Did we come from a system call? */ 825 if (syscall_get_nr(current, regs) >= 0) { 826 /* Restart the system call - no handlers present */ 827 switch (syscall_get_error(current, regs)) { 828 case -ERESTARTNOHAND: 829 case -ERESTARTSYS: 830 case -ERESTARTNOINTR: 831 regs->ax = regs->orig_ax; 832 regs->ip -= 2; 833 break; 834 835 case -ERESTART_RESTARTBLOCK: 836 regs->ax = get_nr_restart_syscall(regs); 837 regs->ip -= 2; 838 break; 839 } 840 } 841 842 /* 843 * If there's no signal to deliver, we just put the saved sigmask 844 * back. 845 */ 846 restore_saved_sigmask(); 847 } 848 849 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 850 { 851 struct task_struct *me = current; 852 853 if (show_unhandled_signals && printk_ratelimit()) { 854 printk("%s" 855 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 856 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, 857 me->comm, me->pid, where, frame, 858 regs->ip, regs->sp, regs->orig_ax); 859 print_vma_addr(KERN_CONT " in ", regs->ip); 860 pr_cont("\n"); 861 } 862 863 force_sig(SIGSEGV, me); 864 } 865 866 #ifdef CONFIG_X86_X32_ABI 867 asmlinkage long sys32_x32_rt_sigreturn(void) 868 { 869 struct pt_regs *regs = current_pt_regs(); 870 struct rt_sigframe_x32 __user *frame; 871 sigset_t set; 872 unsigned long uc_flags; 873 874 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); 875 876 if (!access_ok(frame, sizeof(*frame))) 877 goto badframe; 878 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 879 goto badframe; 880 if (__get_user(uc_flags, &frame->uc.uc_flags)) 881 goto badframe; 882 883 set_current_blocked(&set); 884 885 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 886 goto badframe; 887 888 if (compat_restore_altstack(&frame->uc.uc_stack)) 889 goto badframe; 890 891 return regs->ax; 892 893 badframe: 894 signal_fault(regs, frame, "x32 rt_sigreturn"); 895 return 0; 896 } 897 #endif 898