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