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 29 #include <asm/processor.h> 30 #include <asm/ucontext.h> 31 #include <asm/fpu/internal.h> 32 #include <asm/fpu/signal.h> 33 #include <asm/vdso.h> 34 #include <asm/mce.h> 35 #include <asm/sighandling.h> 36 #include <asm/vm86.h> 37 38 #ifdef CONFIG_X86_64 39 #include <asm/proto.h> 40 #include <asm/ia32_unistd.h> 41 #endif /* CONFIG_X86_64 */ 42 43 #include <asm/syscall.h> 44 #include <asm/syscalls.h> 45 46 #include <asm/sigframe.h> 47 #include <asm/signal.h> 48 49 #define COPY(x) do { \ 50 get_user_ex(regs->x, &sc->x); \ 51 } while (0) 52 53 #define GET_SEG(seg) ({ \ 54 unsigned short tmp; \ 55 get_user_ex(tmp, &sc->seg); \ 56 tmp; \ 57 }) 58 59 #define COPY_SEG(seg) do { \ 60 regs->seg = GET_SEG(seg); \ 61 } while (0) 62 63 #define COPY_SEG_CPL3(seg) do { \ 64 regs->seg = GET_SEG(seg) | 3; \ 65 } while (0) 66 67 #ifdef CONFIG_X86_64 68 /* 69 * If regs->ss will cause an IRET fault, change it. Otherwise leave it 70 * alone. Using this generally makes no sense unless 71 * user_64bit_mode(regs) would return true. 72 */ 73 static void force_valid_ss(struct pt_regs *regs) 74 { 75 u32 ar; 76 asm volatile ("lar %[old_ss], %[ar]\n\t" 77 "jz 1f\n\t" /* If invalid: */ 78 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */ 79 "1:" 80 : [ar] "=r" (ar) 81 : [old_ss] "rm" ((u16)regs->ss)); 82 83 /* 84 * For a valid 64-bit user context, we need DPL 3, type 85 * read-write data or read-write exp-down data, and S and P 86 * set. We can't use VERW because VERW doesn't check the 87 * P bit. 88 */ 89 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK; 90 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) && 91 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN)) 92 regs->ss = __USER_DS; 93 } 94 #endif 95 96 static int restore_sigcontext(struct pt_regs *regs, 97 struct sigcontext __user *sc, 98 unsigned long uc_flags) 99 { 100 unsigned long buf_val; 101 void __user *buf; 102 unsigned int tmpflags; 103 unsigned int err = 0; 104 105 /* Always make any pending restarted system calls return -EINTR */ 106 current->restart_block.fn = do_no_restart_syscall; 107 108 get_user_try { 109 110 #ifdef CONFIG_X86_32 111 set_user_gs(regs, GET_SEG(gs)); 112 COPY_SEG(fs); 113 COPY_SEG(es); 114 COPY_SEG(ds); 115 #endif /* CONFIG_X86_32 */ 116 117 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); 118 COPY(dx); COPY(cx); COPY(ip); COPY(ax); 119 120 #ifdef CONFIG_X86_64 121 COPY(r8); 122 COPY(r9); 123 COPY(r10); 124 COPY(r11); 125 COPY(r12); 126 COPY(r13); 127 COPY(r14); 128 COPY(r15); 129 #endif /* CONFIG_X86_64 */ 130 131 COPY_SEG_CPL3(cs); 132 COPY_SEG_CPL3(ss); 133 134 #ifdef CONFIG_X86_64 135 /* 136 * Fix up SS if needed for the benefit of old DOSEMU and 137 * CRIU. 138 */ 139 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && 140 user_64bit_mode(regs))) 141 force_valid_ss(regs); 142 #endif 143 144 get_user_ex(tmpflags, &sc->flags); 145 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); 146 regs->orig_ax = -1; /* disable syscall checks */ 147 148 get_user_ex(buf_val, &sc->fpstate); 149 buf = (void __user *)buf_val; 150 } get_user_catch(err); 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(VERIFY_WRITE, 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(VERIFY_WRITE, 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 int err = 0; 464 465 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); 466 467 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 468 return -EFAULT; 469 470 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 471 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 472 return -EFAULT; 473 } 474 475 put_user_try { 476 /* Create the ucontext. */ 477 put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags); 478 put_user_ex(0, &frame->uc.uc_link); 479 save_altstack_ex(&frame->uc.uc_stack, regs->sp); 480 481 /* Set up to return from userspace. If provided, use a stub 482 already in userspace. */ 483 /* x86-64 should always use SA_RESTORER. */ 484 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 485 put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode); 486 } else { 487 /* could use a vstub here */ 488 err |= -EFAULT; 489 } 490 } put_user_catch(err); 491 492 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]); 493 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 494 495 if (err) 496 return -EFAULT; 497 498 /* Set up registers for signal handler */ 499 regs->di = sig; 500 /* In case the signal handler was declared without prototypes */ 501 regs->ax = 0; 502 503 /* This also works for non SA_SIGINFO handlers because they expect the 504 next argument after the signal number on the stack. */ 505 regs->si = (unsigned long)&frame->info; 506 regs->dx = (unsigned long)&frame->uc; 507 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 508 509 regs->sp = (unsigned long)frame; 510 511 /* 512 * Set up the CS and SS registers to run signal handlers in 513 * 64-bit mode, even if the handler happens to be interrupting 514 * 32-bit or 16-bit code. 515 * 516 * SS is subtle. In 64-bit mode, we don't need any particular 517 * SS descriptor, but we do need SS to be valid. It's possible 518 * that the old SS is entirely bogus -- this can happen if the 519 * signal we're trying to deliver is #GP or #SS caused by a bad 520 * SS value. We also have a compatbility issue here: DOSEMU 521 * relies on the contents of the SS register indicating the 522 * SS value at the time of the signal, even though that code in 523 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU 524 * avoids relying on sigreturn to restore SS; instead it uses 525 * a trampoline.) So we do our best: if the old SS was valid, 526 * we keep it. Otherwise we replace it. 527 */ 528 regs->cs = __USER_CS; 529 530 if (unlikely(regs->ss != __USER_DS)) 531 force_valid_ss(regs); 532 533 return 0; 534 } 535 #endif /* CONFIG_X86_32 */ 536 537 static int x32_setup_rt_frame(struct ksignal *ksig, 538 compat_sigset_t *set, 539 struct pt_regs *regs) 540 { 541 #ifdef CONFIG_X86_X32_ABI 542 struct rt_sigframe_x32 __user *frame; 543 void __user *restorer; 544 int err = 0; 545 void __user *fpstate = NULL; 546 547 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); 548 549 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 550 return -EFAULT; 551 552 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 553 if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true)) 554 return -EFAULT; 555 } 556 557 put_user_try { 558 /* Create the ucontext. */ 559 put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags); 560 put_user_ex(0, &frame->uc.uc_link); 561 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp); 562 put_user_ex(0, &frame->uc.uc__pad0); 563 564 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 565 restorer = ksig->ka.sa.sa_restorer; 566 } else { 567 /* could use a vstub here */ 568 restorer = NULL; 569 err |= -EFAULT; 570 } 571 put_user_ex(restorer, &frame->pretcode); 572 } put_user_catch(err); 573 574 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, 575 regs, set->sig[0]); 576 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 577 578 if (err) 579 return -EFAULT; 580 581 /* Set up registers for signal handler */ 582 regs->sp = (unsigned long) frame; 583 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 584 585 /* We use the x32 calling convention here... */ 586 regs->di = ksig->sig; 587 regs->si = (unsigned long) &frame->info; 588 regs->dx = (unsigned long) &frame->uc; 589 590 loadsegment(ds, __USER_DS); 591 loadsegment(es, __USER_DS); 592 593 regs->cs = __USER_CS; 594 regs->ss = __USER_DS; 595 #endif /* CONFIG_X86_X32_ABI */ 596 597 return 0; 598 } 599 600 /* 601 * Do a signal return; undo the signal stack. 602 */ 603 #ifdef CONFIG_X86_32 604 asmlinkage unsigned long sys_sigreturn(void) 605 { 606 struct pt_regs *regs = current_pt_regs(); 607 struct sigframe __user *frame; 608 sigset_t set; 609 610 frame = (struct sigframe __user *)(regs->sp - 8); 611 612 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 613 goto badframe; 614 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1 615 && __copy_from_user(&set.sig[1], &frame->extramask, 616 sizeof(frame->extramask)))) 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 asmlinkage long sys_rt_sigreturn(void) 637 { 638 struct pt_regs *regs = current_pt_regs(); 639 struct rt_sigframe __user *frame; 640 sigset_t set; 641 unsigned long uc_flags; 642 643 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 644 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 645 goto badframe; 646 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 647 goto badframe; 648 if (__get_user(uc_flags, &frame->uc.uc_flags)) 649 goto badframe; 650 651 set_current_blocked(&set); 652 653 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 654 goto badframe; 655 656 if (restore_altstack(&frame->uc.uc_stack)) 657 goto badframe; 658 659 return regs->ax; 660 661 badframe: 662 signal_fault(regs, frame, "rt_sigreturn"); 663 return 0; 664 } 665 666 static inline int is_ia32_compat_frame(struct ksignal *ksig) 667 { 668 return IS_ENABLED(CONFIG_IA32_EMULATION) && 669 ksig->ka.sa.sa_flags & SA_IA32_ABI; 670 } 671 672 static inline int is_ia32_frame(struct ksignal *ksig) 673 { 674 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); 675 } 676 677 static inline int is_x32_frame(struct ksignal *ksig) 678 { 679 return IS_ENABLED(CONFIG_X86_X32_ABI) && 680 ksig->ka.sa.sa_flags & SA_X32_ABI; 681 } 682 683 static int 684 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 685 { 686 int usig = ksig->sig; 687 sigset_t *set = sigmask_to_save(); 688 compat_sigset_t *cset = (compat_sigset_t *) set; 689 690 /* Set up the stack frame */ 691 if (is_ia32_frame(ksig)) { 692 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 693 return ia32_setup_rt_frame(usig, ksig, cset, regs); 694 else 695 return ia32_setup_frame(usig, ksig, cset, regs); 696 } else if (is_x32_frame(ksig)) { 697 return x32_setup_rt_frame(ksig, cset, regs); 698 } else { 699 return __setup_rt_frame(ksig->sig, ksig, set, regs); 700 } 701 } 702 703 static void 704 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 705 { 706 bool stepping, failed; 707 struct fpu *fpu = ¤t->thread.fpu; 708 709 if (v8086_mode(regs)) 710 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); 711 712 /* Are we from a system call? */ 713 if (syscall_get_nr(current, regs) >= 0) { 714 /* If so, check system call restarting.. */ 715 switch (syscall_get_error(current, regs)) { 716 case -ERESTART_RESTARTBLOCK: 717 case -ERESTARTNOHAND: 718 regs->ax = -EINTR; 719 break; 720 721 case -ERESTARTSYS: 722 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 723 regs->ax = -EINTR; 724 break; 725 } 726 /* fallthrough */ 727 case -ERESTARTNOINTR: 728 regs->ax = regs->orig_ax; 729 regs->ip -= 2; 730 break; 731 } 732 } 733 734 /* 735 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now 736 * so that register information in the sigcontext is correct and 737 * then notify the tracer before entering the signal handler. 738 */ 739 stepping = test_thread_flag(TIF_SINGLESTEP); 740 if (stepping) 741 user_disable_single_step(current); 742 743 failed = (setup_rt_frame(ksig, regs) < 0); 744 if (!failed) { 745 /* 746 * Clear the direction flag as per the ABI for function entry. 747 * 748 * Clear RF when entering the signal handler, because 749 * it might disable possible debug exception from the 750 * signal handler. 751 * 752 * Clear TF for the case when it wasn't set by debugger to 753 * avoid the recursive send_sigtrap() in SIGTRAP handler. 754 */ 755 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); 756 /* 757 * Ensure the signal handler starts with the new fpu state. 758 */ 759 if (fpu->initialized) 760 fpu__clear(fpu); 761 } 762 signal_setup_done(failed, ksig, stepping); 763 } 764 765 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) 766 { 767 /* 768 * This function is fundamentally broken as currently 769 * implemented. 770 * 771 * The idea is that we want to trigger a call to the 772 * restart_block() syscall and that we want in_ia32_syscall(), 773 * in_x32_syscall(), etc. to match whatever they were in the 774 * syscall being restarted. We assume that the syscall 775 * instruction at (regs->ip - 2) matches whatever syscall 776 * instruction we used to enter in the first place. 777 * 778 * The problem is that we can get here when ptrace pokes 779 * syscall-like values into regs even if we're not in a syscall 780 * at all. 781 * 782 * For now, we maintain historical behavior and guess based on 783 * stored state. We could do better by saving the actual 784 * syscall arch in restart_block or (with caveats on x32) by 785 * checking if regs->ip points to 'int $0x80'. The current 786 * behavior is incorrect if a tracer has a different bitness 787 * than the tracee. 788 */ 789 #ifdef CONFIG_IA32_EMULATION 790 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED)) 791 return __NR_ia32_restart_syscall; 792 #endif 793 #ifdef CONFIG_X86_X32_ABI 794 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); 795 #else 796 return __NR_restart_syscall; 797 #endif 798 } 799 800 /* 801 * Note that 'init' is a special process: it doesn't get signals it doesn't 802 * want to handle. Thus you cannot kill init even with a SIGKILL even by 803 * mistake. 804 */ 805 void do_signal(struct pt_regs *regs) 806 { 807 struct ksignal ksig; 808 809 if (get_signal(&ksig)) { 810 /* Whee! Actually deliver the signal. */ 811 handle_signal(&ksig, regs); 812 return; 813 } 814 815 /* Did we come from a system call? */ 816 if (syscall_get_nr(current, regs) >= 0) { 817 /* Restart the system call - no handlers present */ 818 switch (syscall_get_error(current, regs)) { 819 case -ERESTARTNOHAND: 820 case -ERESTARTSYS: 821 case -ERESTARTNOINTR: 822 regs->ax = regs->orig_ax; 823 regs->ip -= 2; 824 break; 825 826 case -ERESTART_RESTARTBLOCK: 827 regs->ax = get_nr_restart_syscall(regs); 828 regs->ip -= 2; 829 break; 830 } 831 } 832 833 /* 834 * If there's no signal to deliver, we just put the saved sigmask 835 * back. 836 */ 837 restore_saved_sigmask(); 838 } 839 840 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 841 { 842 struct task_struct *me = current; 843 844 if (show_unhandled_signals && printk_ratelimit()) { 845 printk("%s" 846 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 847 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, 848 me->comm, me->pid, where, frame, 849 regs->ip, regs->sp, regs->orig_ax); 850 print_vma_addr(KERN_CONT " in ", regs->ip); 851 pr_cont("\n"); 852 } 853 854 force_sig(SIGSEGV, me); 855 } 856 857 #ifdef CONFIG_X86_X32_ABI 858 asmlinkage long sys32_x32_rt_sigreturn(void) 859 { 860 struct pt_regs *regs = current_pt_regs(); 861 struct rt_sigframe_x32 __user *frame; 862 sigset_t set; 863 unsigned long uc_flags; 864 865 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); 866 867 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 868 goto badframe; 869 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 870 goto badframe; 871 if (__get_user(uc_flags, &frame->uc.uc_flags)) 872 goto badframe; 873 874 set_current_blocked(&set); 875 876 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 877 goto badframe; 878 879 if (compat_restore_altstack(&frame->uc.uc_stack)) 880 goto badframe; 881 882 return regs->ax; 883 884 badframe: 885 signal_fault(regs, frame, "x32 rt_sigreturn"); 886 return 0; 887 } 888 #endif 889