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 #ifdef CONFIG_X86_64 51 /* 52 * If regs->ss will cause an IRET fault, change it. Otherwise leave it 53 * alone. Using this generally makes no sense unless 54 * user_64bit_mode(regs) would return true. 55 */ 56 static void force_valid_ss(struct pt_regs *regs) 57 { 58 u32 ar; 59 asm volatile ("lar %[old_ss], %[ar]\n\t" 60 "jz 1f\n\t" /* If invalid: */ 61 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */ 62 "1:" 63 : [ar] "=r" (ar) 64 : [old_ss] "rm" ((u16)regs->ss)); 65 66 /* 67 * For a valid 64-bit user context, we need DPL 3, type 68 * read-write data or read-write exp-down data, and S and P 69 * set. We can't use VERW because VERW doesn't check the 70 * P bit. 71 */ 72 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK; 73 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) && 74 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN)) 75 regs->ss = __USER_DS; 76 } 77 # define CONTEXT_COPY_SIZE offsetof(struct sigcontext, reserved1) 78 #else 79 # define CONTEXT_COPY_SIZE sizeof(struct sigcontext) 80 #endif 81 82 static int restore_sigcontext(struct pt_regs *regs, 83 struct sigcontext __user *usc, 84 unsigned long uc_flags) 85 { 86 struct sigcontext sc; 87 88 /* Always make any pending restarted system calls return -EINTR */ 89 current->restart_block.fn = do_no_restart_syscall; 90 91 if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE)) 92 return -EFAULT; 93 94 #ifdef CONFIG_X86_32 95 set_user_gs(regs, sc.gs); 96 regs->fs = sc.fs; 97 regs->es = sc.es; 98 regs->ds = sc.ds; 99 #endif /* CONFIG_X86_32 */ 100 101 regs->bx = sc.bx; 102 regs->cx = sc.cx; 103 regs->dx = sc.dx; 104 regs->si = sc.si; 105 regs->di = sc.di; 106 regs->bp = sc.bp; 107 regs->ax = sc.ax; 108 regs->sp = sc.sp; 109 regs->ip = sc.ip; 110 111 #ifdef CONFIG_X86_64 112 regs->r8 = sc.r8; 113 regs->r9 = sc.r9; 114 regs->r10 = sc.r10; 115 regs->r11 = sc.r11; 116 regs->r12 = sc.r12; 117 regs->r13 = sc.r13; 118 regs->r14 = sc.r14; 119 regs->r15 = sc.r15; 120 #endif /* CONFIG_X86_64 */ 121 122 /* Get CS/SS and force CPL3 */ 123 regs->cs = sc.cs | 0x03; 124 regs->ss = sc.ss | 0x03; 125 126 regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS); 127 /* disable syscall checks */ 128 regs->orig_ax = -1; 129 130 #ifdef CONFIG_X86_64 131 /* 132 * Fix up SS if needed for the benefit of old DOSEMU and 133 * CRIU. 134 */ 135 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs))) 136 force_valid_ss(regs); 137 #endif 138 139 return fpu__restore_sig((void __user *)sc.fpstate, 140 IS_ENABLED(CONFIG_X86_32)); 141 } 142 143 static __always_inline int 144 __unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate, 145 struct pt_regs *regs, unsigned long mask) 146 { 147 #ifdef CONFIG_X86_32 148 unsafe_put_user(get_user_gs(regs), 149 (unsigned int __user *)&sc->gs, Efault); 150 unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault); 151 unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault); 152 unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault); 153 #endif /* CONFIG_X86_32 */ 154 155 unsafe_put_user(regs->di, &sc->di, Efault); 156 unsafe_put_user(regs->si, &sc->si, Efault); 157 unsafe_put_user(regs->bp, &sc->bp, Efault); 158 unsafe_put_user(regs->sp, &sc->sp, Efault); 159 unsafe_put_user(regs->bx, &sc->bx, Efault); 160 unsafe_put_user(regs->dx, &sc->dx, Efault); 161 unsafe_put_user(regs->cx, &sc->cx, Efault); 162 unsafe_put_user(regs->ax, &sc->ax, Efault); 163 #ifdef CONFIG_X86_64 164 unsafe_put_user(regs->r8, &sc->r8, Efault); 165 unsafe_put_user(regs->r9, &sc->r9, Efault); 166 unsafe_put_user(regs->r10, &sc->r10, Efault); 167 unsafe_put_user(regs->r11, &sc->r11, Efault); 168 unsafe_put_user(regs->r12, &sc->r12, Efault); 169 unsafe_put_user(regs->r13, &sc->r13, Efault); 170 unsafe_put_user(regs->r14, &sc->r14, Efault); 171 unsafe_put_user(regs->r15, &sc->r15, Efault); 172 #endif /* CONFIG_X86_64 */ 173 174 unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault); 175 unsafe_put_user(current->thread.error_code, &sc->err, Efault); 176 unsafe_put_user(regs->ip, &sc->ip, Efault); 177 #ifdef CONFIG_X86_32 178 unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault); 179 unsafe_put_user(regs->flags, &sc->flags, Efault); 180 unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault); 181 unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault); 182 #else /* !CONFIG_X86_32 */ 183 unsafe_put_user(regs->flags, &sc->flags, Efault); 184 unsafe_put_user(regs->cs, &sc->cs, Efault); 185 unsafe_put_user(0, &sc->gs, Efault); 186 unsafe_put_user(0, &sc->fs, Efault); 187 unsafe_put_user(regs->ss, &sc->ss, Efault); 188 #endif /* CONFIG_X86_32 */ 189 190 unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault); 191 192 /* non-iBCS2 extensions.. */ 193 unsafe_put_user(mask, &sc->oldmask, Efault); 194 unsafe_put_user(current->thread.cr2, &sc->cr2, Efault); 195 return 0; 196 Efault: 197 return -EFAULT; 198 } 199 200 #define unsafe_put_sigcontext(sc, fp, regs, set, label) \ 201 do { \ 202 if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \ 203 goto label; \ 204 } while(0); 205 206 /* 207 * Set up a signal frame. 208 */ 209 210 /* 211 * Determine which stack to use.. 212 */ 213 static unsigned long align_sigframe(unsigned long sp) 214 { 215 #ifdef CONFIG_X86_32 216 /* 217 * Align the stack pointer according to the i386 ABI, 218 * i.e. so that on function entry ((sp + 4) & 15) == 0. 219 */ 220 sp = ((sp + 4) & -16ul) - 4; 221 #else /* !CONFIG_X86_32 */ 222 sp = round_down(sp, 16) - 8; 223 #endif 224 return sp; 225 } 226 227 static void __user * 228 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, 229 void __user **fpstate) 230 { 231 /* Default to using normal stack */ 232 unsigned long math_size = 0; 233 unsigned long sp = regs->sp; 234 unsigned long buf_fx = 0; 235 int onsigstack = on_sig_stack(sp); 236 int ret; 237 238 /* redzone */ 239 if (IS_ENABLED(CONFIG_X86_64)) 240 sp -= 128; 241 242 /* This is the X/Open sanctioned signal stack switching. */ 243 if (ka->sa.sa_flags & SA_ONSTACK) { 244 if (sas_ss_flags(sp) == 0) 245 sp = current->sas_ss_sp + current->sas_ss_size; 246 } else if (IS_ENABLED(CONFIG_X86_32) && 247 !onsigstack && 248 regs->ss != __USER_DS && 249 !(ka->sa.sa_flags & SA_RESTORER) && 250 ka->sa.sa_restorer) { 251 /* This is the legacy signal stack switching. */ 252 sp = (unsigned long) ka->sa.sa_restorer; 253 } 254 255 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32), 256 &buf_fx, &math_size); 257 *fpstate = (void __user *)sp; 258 259 sp = align_sigframe(sp - frame_size); 260 261 /* 262 * If we are on the alternate signal stack and would overflow it, don't. 263 * Return an always-bogus address instead so we will die with SIGSEGV. 264 */ 265 if (onsigstack && !likely(on_sig_stack(sp))) 266 return (void __user *)-1L; 267 268 /* save i387 and extended state */ 269 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size); 270 if (ret < 0) 271 return (void __user *)-1L; 272 273 return (void __user *)sp; 274 } 275 276 #ifdef CONFIG_X86_32 277 static const struct { 278 u16 poplmovl; 279 u32 val; 280 u16 int80; 281 } __attribute__((packed)) retcode = { 282 0xb858, /* popl %eax; movl $..., %eax */ 283 __NR_sigreturn, 284 0x80cd, /* int $0x80 */ 285 }; 286 287 static const struct { 288 u8 movl; 289 u32 val; 290 u16 int80; 291 u8 pad; 292 } __attribute__((packed)) rt_retcode = { 293 0xb8, /* movl $..., %eax */ 294 __NR_rt_sigreturn, 295 0x80cd, /* int $0x80 */ 296 0 297 }; 298 299 static int 300 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, 301 struct pt_regs *regs) 302 { 303 struct sigframe __user *frame; 304 void __user *restorer; 305 void __user *fp = NULL; 306 307 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 308 309 if (!user_access_begin(frame, sizeof(*frame))) 310 return -EFAULT; 311 312 unsafe_put_user(sig, &frame->sig, Efault); 313 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault); 314 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault); 315 if (current->mm->context.vdso) 316 restorer = current->mm->context.vdso + 317 vdso_image_32.sym___kernel_sigreturn; 318 else 319 restorer = &frame->retcode; 320 if (ksig->ka.sa.sa_flags & SA_RESTORER) 321 restorer = ksig->ka.sa.sa_restorer; 322 323 /* Set up to return from userspace. */ 324 unsafe_put_user(restorer, &frame->pretcode, Efault); 325 326 /* 327 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80 328 * 329 * WE DO NOT USE IT ANY MORE! It's only left here for historical 330 * reasons and because gdb uses it as a signature to notice 331 * signal handler stack frames. 332 */ 333 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault); 334 user_access_end(); 335 336 /* Set up registers for signal handler */ 337 regs->sp = (unsigned long)frame; 338 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 339 regs->ax = (unsigned long)sig; 340 regs->dx = 0; 341 regs->cx = 0; 342 343 regs->ds = __USER_DS; 344 regs->es = __USER_DS; 345 regs->ss = __USER_DS; 346 regs->cs = __USER_CS; 347 348 return 0; 349 350 Efault: 351 user_access_end(); 352 return -EFAULT; 353 } 354 355 static int __setup_rt_frame(int sig, struct ksignal *ksig, 356 sigset_t *set, struct pt_regs *regs) 357 { 358 struct rt_sigframe __user *frame; 359 void __user *restorer; 360 void __user *fp = NULL; 361 362 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 363 364 if (!user_access_begin(frame, sizeof(*frame))) 365 return -EFAULT; 366 367 unsafe_put_user(sig, &frame->sig, Efault); 368 unsafe_put_user(&frame->info, &frame->pinfo, Efault); 369 unsafe_put_user(&frame->uc, &frame->puc, Efault); 370 371 /* Create the ucontext. */ 372 if (static_cpu_has(X86_FEATURE_XSAVE)) 373 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault); 374 else 375 unsafe_put_user(0, &frame->uc.uc_flags, Efault); 376 unsafe_put_user(0, &frame->uc.uc_link, Efault); 377 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 378 379 /* Set up to return from userspace. */ 380 restorer = current->mm->context.vdso + 381 vdso_image_32.sym___kernel_rt_sigreturn; 382 if (ksig->ka.sa.sa_flags & SA_RESTORER) 383 restorer = ksig->ka.sa.sa_restorer; 384 unsafe_put_user(restorer, &frame->pretcode, Efault); 385 386 /* 387 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 388 * 389 * WE DO NOT USE IT ANY MORE! It's only left here for historical 390 * reasons and because gdb uses it as a signature to notice 391 * signal handler stack frames. 392 */ 393 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault); 394 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 395 unsafe_put_user(*(__u64 *)set, 396 (__u64 __user *)&frame->uc.uc_sigmask, Efault); 397 user_access_end(); 398 399 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 400 return -EFAULT; 401 402 /* Set up registers for signal handler */ 403 regs->sp = (unsigned long)frame; 404 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 405 regs->ax = (unsigned long)sig; 406 regs->dx = (unsigned long)&frame->info; 407 regs->cx = (unsigned long)&frame->uc; 408 409 regs->ds = __USER_DS; 410 regs->es = __USER_DS; 411 regs->ss = __USER_DS; 412 regs->cs = __USER_CS; 413 414 return 0; 415 Efault: 416 user_access_end(); 417 return -EFAULT; 418 } 419 #else /* !CONFIG_X86_32 */ 420 static unsigned long frame_uc_flags(struct pt_regs *regs) 421 { 422 unsigned long flags; 423 424 if (boot_cpu_has(X86_FEATURE_XSAVE)) 425 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS; 426 else 427 flags = UC_SIGCONTEXT_SS; 428 429 if (likely(user_64bit_mode(regs))) 430 flags |= UC_STRICT_RESTORE_SS; 431 432 return flags; 433 } 434 435 static int __setup_rt_frame(int sig, struct ksignal *ksig, 436 sigset_t *set, struct pt_regs *regs) 437 { 438 struct rt_sigframe __user *frame; 439 void __user *fp = NULL; 440 unsigned long uc_flags; 441 442 /* x86-64 should always use SA_RESTORER. */ 443 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 444 return -EFAULT; 445 446 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); 447 uc_flags = frame_uc_flags(regs); 448 449 if (!user_access_begin(frame, sizeof(*frame))) 450 return -EFAULT; 451 452 /* Create the ucontext. */ 453 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 454 unsafe_put_user(0, &frame->uc.uc_link, Efault); 455 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 456 457 /* Set up to return from userspace. If provided, use a stub 458 already in userspace. */ 459 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault); 460 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 461 unsafe_put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0], Efault); 462 user_access_end(); 463 464 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 465 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 466 return -EFAULT; 467 } 468 469 /* Set up registers for signal handler */ 470 regs->di = sig; 471 /* In case the signal handler was declared without prototypes */ 472 regs->ax = 0; 473 474 /* This also works for non SA_SIGINFO handlers because they expect the 475 next argument after the signal number on the stack. */ 476 regs->si = (unsigned long)&frame->info; 477 regs->dx = (unsigned long)&frame->uc; 478 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 479 480 regs->sp = (unsigned long)frame; 481 482 /* 483 * Set up the CS and SS registers to run signal handlers in 484 * 64-bit mode, even if the handler happens to be interrupting 485 * 32-bit or 16-bit code. 486 * 487 * SS is subtle. In 64-bit mode, we don't need any particular 488 * SS descriptor, but we do need SS to be valid. It's possible 489 * that the old SS is entirely bogus -- this can happen if the 490 * signal we're trying to deliver is #GP or #SS caused by a bad 491 * SS value. We also have a compatbility issue here: DOSEMU 492 * relies on the contents of the SS register indicating the 493 * SS value at the time of the signal, even though that code in 494 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU 495 * avoids relying on sigreturn to restore SS; instead it uses 496 * a trampoline.) So we do our best: if the old SS was valid, 497 * we keep it. Otherwise we replace it. 498 */ 499 regs->cs = __USER_CS; 500 501 if (unlikely(regs->ss != __USER_DS)) 502 force_valid_ss(regs); 503 504 return 0; 505 506 Efault: 507 user_access_end(); 508 return -EFAULT; 509 } 510 #endif /* CONFIG_X86_32 */ 511 512 static int x32_setup_rt_frame(struct ksignal *ksig, 513 compat_sigset_t *set, 514 struct pt_regs *regs) 515 { 516 #ifdef CONFIG_X86_X32_ABI 517 struct rt_sigframe_x32 __user *frame; 518 unsigned long uc_flags; 519 void __user *restorer; 520 int err = 0; 521 void __user *fp = NULL; 522 523 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 524 return -EFAULT; 525 526 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 527 528 if (!access_ok(frame, sizeof(*frame))) 529 return -EFAULT; 530 531 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 532 if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true)) 533 return -EFAULT; 534 } 535 536 uc_flags = frame_uc_flags(regs); 537 538 if (!user_access_begin(frame, sizeof(*frame))) 539 return -EFAULT; 540 541 /* Create the ucontext. */ 542 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 543 unsafe_put_user(0, &frame->uc.uc_link, Efault); 544 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 545 unsafe_put_user(0, &frame->uc.uc__pad0, Efault); 546 restorer = ksig->ka.sa.sa_restorer; 547 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault); 548 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 549 user_access_end(); 550 err |= __put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask); 551 552 if (err) 553 return -EFAULT; 554 555 /* Set up registers for signal handler */ 556 regs->sp = (unsigned long) frame; 557 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 558 559 /* We use the x32 calling convention here... */ 560 regs->di = ksig->sig; 561 regs->si = (unsigned long) &frame->info; 562 regs->dx = (unsigned long) &frame->uc; 563 564 loadsegment(ds, __USER_DS); 565 loadsegment(es, __USER_DS); 566 567 regs->cs = __USER_CS; 568 regs->ss = __USER_DS; 569 #endif /* CONFIG_X86_X32_ABI */ 570 571 return 0; 572 #ifdef CONFIG_X86_X32_ABI 573 Efault: 574 user_access_end(); 575 return -EFAULT; 576 #endif 577 } 578 579 /* 580 * Do a signal return; undo the signal stack. 581 */ 582 #ifdef CONFIG_X86_32 583 SYSCALL_DEFINE0(sigreturn) 584 { 585 struct pt_regs *regs = current_pt_regs(); 586 struct sigframe __user *frame; 587 sigset_t set; 588 589 frame = (struct sigframe __user *)(regs->sp - 8); 590 591 if (!access_ok(frame, sizeof(*frame))) 592 goto badframe; 593 if (__get_user(set.sig[0], &frame->sc.oldmask) || 594 __get_user(set.sig[1], &frame->extramask[0])) 595 goto badframe; 596 597 set_current_blocked(&set); 598 599 /* 600 * x86_32 has no uc_flags bits relevant to restore_sigcontext. 601 * Save a few cycles by skipping the __get_user. 602 */ 603 if (restore_sigcontext(regs, &frame->sc, 0)) 604 goto badframe; 605 return regs->ax; 606 607 badframe: 608 signal_fault(regs, frame, "sigreturn"); 609 610 return 0; 611 } 612 #endif /* CONFIG_X86_32 */ 613 614 SYSCALL_DEFINE0(rt_sigreturn) 615 { 616 struct pt_regs *regs = current_pt_regs(); 617 struct rt_sigframe __user *frame; 618 sigset_t set; 619 unsigned long uc_flags; 620 621 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 622 if (!access_ok(frame, sizeof(*frame))) 623 goto badframe; 624 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask)) 625 goto badframe; 626 if (__get_user(uc_flags, &frame->uc.uc_flags)) 627 goto badframe; 628 629 set_current_blocked(&set); 630 631 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 632 goto badframe; 633 634 if (restore_altstack(&frame->uc.uc_stack)) 635 goto badframe; 636 637 return regs->ax; 638 639 badframe: 640 signal_fault(regs, frame, "rt_sigreturn"); 641 return 0; 642 } 643 644 static inline int is_ia32_compat_frame(struct ksignal *ksig) 645 { 646 return IS_ENABLED(CONFIG_IA32_EMULATION) && 647 ksig->ka.sa.sa_flags & SA_IA32_ABI; 648 } 649 650 static inline int is_ia32_frame(struct ksignal *ksig) 651 { 652 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); 653 } 654 655 static inline int is_x32_frame(struct ksignal *ksig) 656 { 657 return IS_ENABLED(CONFIG_X86_X32_ABI) && 658 ksig->ka.sa.sa_flags & SA_X32_ABI; 659 } 660 661 static int 662 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 663 { 664 int usig = ksig->sig; 665 sigset_t *set = sigmask_to_save(); 666 compat_sigset_t *cset = (compat_sigset_t *) set; 667 668 /* Perform fixup for the pre-signal frame. */ 669 rseq_signal_deliver(ksig, regs); 670 671 /* Set up the stack frame */ 672 if (is_ia32_frame(ksig)) { 673 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 674 return ia32_setup_rt_frame(usig, ksig, cset, regs); 675 else 676 return ia32_setup_frame(usig, ksig, cset, regs); 677 } else if (is_x32_frame(ksig)) { 678 return x32_setup_rt_frame(ksig, cset, regs); 679 } else { 680 return __setup_rt_frame(ksig->sig, ksig, set, regs); 681 } 682 } 683 684 static void 685 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 686 { 687 bool stepping, failed; 688 struct fpu *fpu = ¤t->thread.fpu; 689 690 if (v8086_mode(regs)) 691 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); 692 693 /* Are we from a system call? */ 694 if (syscall_get_nr(current, regs) >= 0) { 695 /* If so, check system call restarting.. */ 696 switch (syscall_get_error(current, regs)) { 697 case -ERESTART_RESTARTBLOCK: 698 case -ERESTARTNOHAND: 699 regs->ax = -EINTR; 700 break; 701 702 case -ERESTARTSYS: 703 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 704 regs->ax = -EINTR; 705 break; 706 } 707 /* fallthrough */ 708 case -ERESTARTNOINTR: 709 regs->ax = regs->orig_ax; 710 regs->ip -= 2; 711 break; 712 } 713 } 714 715 /* 716 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now 717 * so that register information in the sigcontext is correct and 718 * then notify the tracer before entering the signal handler. 719 */ 720 stepping = test_thread_flag(TIF_SINGLESTEP); 721 if (stepping) 722 user_disable_single_step(current); 723 724 failed = (setup_rt_frame(ksig, regs) < 0); 725 if (!failed) { 726 /* 727 * Clear the direction flag as per the ABI for function entry. 728 * 729 * Clear RF when entering the signal handler, because 730 * it might disable possible debug exception from the 731 * signal handler. 732 * 733 * Clear TF for the case when it wasn't set by debugger to 734 * avoid the recursive send_sigtrap() in SIGTRAP handler. 735 */ 736 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); 737 /* 738 * Ensure the signal handler starts with the new fpu state. 739 */ 740 fpu__clear(fpu); 741 } 742 signal_setup_done(failed, ksig, stepping); 743 } 744 745 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) 746 { 747 /* 748 * This function is fundamentally broken as currently 749 * implemented. 750 * 751 * The idea is that we want to trigger a call to the 752 * restart_block() syscall and that we want in_ia32_syscall(), 753 * in_x32_syscall(), etc. to match whatever they were in the 754 * syscall being restarted. We assume that the syscall 755 * instruction at (regs->ip - 2) matches whatever syscall 756 * instruction we used to enter in the first place. 757 * 758 * The problem is that we can get here when ptrace pokes 759 * syscall-like values into regs even if we're not in a syscall 760 * at all. 761 * 762 * For now, we maintain historical behavior and guess based on 763 * stored state. We could do better by saving the actual 764 * syscall arch in restart_block or (with caveats on x32) by 765 * checking if regs->ip points to 'int $0x80'. The current 766 * behavior is incorrect if a tracer has a different bitness 767 * than the tracee. 768 */ 769 #ifdef CONFIG_IA32_EMULATION 770 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED)) 771 return __NR_ia32_restart_syscall; 772 #endif 773 #ifdef CONFIG_X86_X32_ABI 774 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); 775 #else 776 return __NR_restart_syscall; 777 #endif 778 } 779 780 /* 781 * Note that 'init' is a special process: it doesn't get signals it doesn't 782 * want to handle. Thus you cannot kill init even with a SIGKILL even by 783 * mistake. 784 */ 785 void do_signal(struct pt_regs *regs) 786 { 787 struct ksignal ksig; 788 789 if (get_signal(&ksig)) { 790 /* Whee! Actually deliver the signal. */ 791 handle_signal(&ksig, regs); 792 return; 793 } 794 795 /* Did we come from a system call? */ 796 if (syscall_get_nr(current, regs) >= 0) { 797 /* Restart the system call - no handlers present */ 798 switch (syscall_get_error(current, regs)) { 799 case -ERESTARTNOHAND: 800 case -ERESTARTSYS: 801 case -ERESTARTNOINTR: 802 regs->ax = regs->orig_ax; 803 regs->ip -= 2; 804 break; 805 806 case -ERESTART_RESTARTBLOCK: 807 regs->ax = get_nr_restart_syscall(regs); 808 regs->ip -= 2; 809 break; 810 } 811 } 812 813 /* 814 * If there's no signal to deliver, we just put the saved sigmask 815 * back. 816 */ 817 restore_saved_sigmask(); 818 } 819 820 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 821 { 822 struct task_struct *me = current; 823 824 if (show_unhandled_signals && printk_ratelimit()) { 825 printk("%s" 826 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 827 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, 828 me->comm, me->pid, where, frame, 829 regs->ip, regs->sp, regs->orig_ax); 830 print_vma_addr(KERN_CONT " in ", regs->ip); 831 pr_cont("\n"); 832 } 833 834 force_sig(SIGSEGV); 835 } 836 837 #ifdef CONFIG_X86_X32_ABI 838 asmlinkage long sys32_x32_rt_sigreturn(void) 839 { 840 struct pt_regs *regs = current_pt_regs(); 841 struct rt_sigframe_x32 __user *frame; 842 sigset_t set; 843 unsigned long uc_flags; 844 845 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); 846 847 if (!access_ok(frame, sizeof(*frame))) 848 goto badframe; 849 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask)) 850 goto badframe; 851 if (__get_user(uc_flags, &frame->uc.uc_flags)) 852 goto badframe; 853 854 set_current_blocked(&set); 855 856 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 857 goto badframe; 858 859 if (compat_restore_altstack(&frame->uc.uc_stack)) 860 goto badframe; 861 862 return regs->ax; 863 864 badframe: 865 signal_fault(regs, frame, "x32 rt_sigreturn"); 866 return 0; 867 } 868 #endif 869