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/sigframe.h> 46 #include <asm/signal.h> 47 48 #ifdef CONFIG_X86_64 49 /* 50 * If regs->ss will cause an IRET fault, change it. Otherwise leave it 51 * alone. Using this generally makes no sense unless 52 * user_64bit_mode(regs) would return true. 53 */ 54 static void force_valid_ss(struct pt_regs *regs) 55 { 56 u32 ar; 57 asm volatile ("lar %[old_ss], %[ar]\n\t" 58 "jz 1f\n\t" /* If invalid: */ 59 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */ 60 "1:" 61 : [ar] "=r" (ar) 62 : [old_ss] "rm" ((u16)regs->ss)); 63 64 /* 65 * For a valid 64-bit user context, we need DPL 3, type 66 * read-write data or read-write exp-down data, and S and P 67 * set. We can't use VERW because VERW doesn't check the 68 * P bit. 69 */ 70 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK; 71 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) && 72 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN)) 73 regs->ss = __USER_DS; 74 } 75 # define CONTEXT_COPY_SIZE offsetof(struct sigcontext, reserved1) 76 #else 77 # define CONTEXT_COPY_SIZE sizeof(struct sigcontext) 78 #endif 79 80 static int restore_sigcontext(struct pt_regs *regs, 81 struct sigcontext __user *usc, 82 unsigned long uc_flags) 83 { 84 struct sigcontext sc; 85 86 /* Always make any pending restarted system calls return -EINTR */ 87 current->restart_block.fn = do_no_restart_syscall; 88 89 if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE)) 90 return -EFAULT; 91 92 #ifdef CONFIG_X86_32 93 set_user_gs(regs, sc.gs); 94 regs->fs = sc.fs; 95 regs->es = sc.es; 96 regs->ds = sc.ds; 97 #endif /* CONFIG_X86_32 */ 98 99 regs->bx = sc.bx; 100 regs->cx = sc.cx; 101 regs->dx = sc.dx; 102 regs->si = sc.si; 103 regs->di = sc.di; 104 regs->bp = sc.bp; 105 regs->ax = sc.ax; 106 regs->sp = sc.sp; 107 regs->ip = sc.ip; 108 109 #ifdef CONFIG_X86_64 110 regs->r8 = sc.r8; 111 regs->r9 = sc.r9; 112 regs->r10 = sc.r10; 113 regs->r11 = sc.r11; 114 regs->r12 = sc.r12; 115 regs->r13 = sc.r13; 116 regs->r14 = sc.r14; 117 regs->r15 = sc.r15; 118 #endif /* CONFIG_X86_64 */ 119 120 /* Get CS/SS and force CPL3 */ 121 regs->cs = sc.cs | 0x03; 122 regs->ss = sc.ss | 0x03; 123 124 regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS); 125 /* disable syscall checks */ 126 regs->orig_ax = -1; 127 128 #ifdef CONFIG_X86_64 129 /* 130 * Fix up SS if needed for the benefit of old DOSEMU and 131 * CRIU. 132 */ 133 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs))) 134 force_valid_ss(regs); 135 #endif 136 137 return fpu__restore_sig((void __user *)sc.fpstate, 138 IS_ENABLED(CONFIG_X86_32)); 139 } 140 141 static __always_inline int 142 __unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate, 143 struct pt_regs *regs, unsigned long mask) 144 { 145 #ifdef CONFIG_X86_32 146 unsafe_put_user(get_user_gs(regs), 147 (unsigned int __user *)&sc->gs, Efault); 148 unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault); 149 unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault); 150 unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault); 151 #endif /* CONFIG_X86_32 */ 152 153 unsafe_put_user(regs->di, &sc->di, Efault); 154 unsafe_put_user(regs->si, &sc->si, Efault); 155 unsafe_put_user(regs->bp, &sc->bp, Efault); 156 unsafe_put_user(regs->sp, &sc->sp, Efault); 157 unsafe_put_user(regs->bx, &sc->bx, Efault); 158 unsafe_put_user(regs->dx, &sc->dx, Efault); 159 unsafe_put_user(regs->cx, &sc->cx, Efault); 160 unsafe_put_user(regs->ax, &sc->ax, Efault); 161 #ifdef CONFIG_X86_64 162 unsafe_put_user(regs->r8, &sc->r8, Efault); 163 unsafe_put_user(regs->r9, &sc->r9, Efault); 164 unsafe_put_user(regs->r10, &sc->r10, Efault); 165 unsafe_put_user(regs->r11, &sc->r11, Efault); 166 unsafe_put_user(regs->r12, &sc->r12, Efault); 167 unsafe_put_user(regs->r13, &sc->r13, Efault); 168 unsafe_put_user(regs->r14, &sc->r14, Efault); 169 unsafe_put_user(regs->r15, &sc->r15, Efault); 170 #endif /* CONFIG_X86_64 */ 171 172 unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault); 173 unsafe_put_user(current->thread.error_code, &sc->err, Efault); 174 unsafe_put_user(regs->ip, &sc->ip, Efault); 175 #ifdef CONFIG_X86_32 176 unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault); 177 unsafe_put_user(regs->flags, &sc->flags, Efault); 178 unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault); 179 unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault); 180 #else /* !CONFIG_X86_32 */ 181 unsafe_put_user(regs->flags, &sc->flags, Efault); 182 unsafe_put_user(regs->cs, &sc->cs, Efault); 183 unsafe_put_user(0, &sc->gs, Efault); 184 unsafe_put_user(0, &sc->fs, Efault); 185 unsafe_put_user(regs->ss, &sc->ss, Efault); 186 #endif /* CONFIG_X86_32 */ 187 188 unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault); 189 190 /* non-iBCS2 extensions.. */ 191 unsafe_put_user(mask, &sc->oldmask, Efault); 192 unsafe_put_user(current->thread.cr2, &sc->cr2, Efault); 193 return 0; 194 Efault: 195 return -EFAULT; 196 } 197 198 #define unsafe_put_sigcontext(sc, fp, regs, set, label) \ 199 do { \ 200 if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \ 201 goto label; \ 202 } while(0); 203 204 #define unsafe_put_sigmask(set, frame, label) \ 205 unsafe_put_user(*(__u64 *)(set), \ 206 (__u64 __user *)&(frame)->uc.uc_sigmask, \ 207 label) 208 209 /* 210 * Set up a signal frame. 211 */ 212 213 /* 214 * Determine which stack to use.. 215 */ 216 static unsigned long align_sigframe(unsigned long sp) 217 { 218 #ifdef CONFIG_X86_32 219 /* 220 * Align the stack pointer according to the i386 ABI, 221 * i.e. so that on function entry ((sp + 4) & 15) == 0. 222 */ 223 sp = ((sp + 4) & -16ul) - 4; 224 #else /* !CONFIG_X86_32 */ 225 sp = round_down(sp, 16) - 8; 226 #endif 227 return sp; 228 } 229 230 static void __user * 231 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, 232 void __user **fpstate) 233 { 234 /* Default to using normal stack */ 235 unsigned long math_size = 0; 236 unsigned long sp = regs->sp; 237 unsigned long buf_fx = 0; 238 int onsigstack = on_sig_stack(sp); 239 int ret; 240 241 /* redzone */ 242 if (IS_ENABLED(CONFIG_X86_64)) 243 sp -= 128; 244 245 /* This is the X/Open sanctioned signal stack switching. */ 246 if (ka->sa.sa_flags & SA_ONSTACK) { 247 if (sas_ss_flags(sp) == 0) 248 sp = current->sas_ss_sp + current->sas_ss_size; 249 } else if (IS_ENABLED(CONFIG_X86_32) && 250 !onsigstack && 251 regs->ss != __USER_DS && 252 !(ka->sa.sa_flags & SA_RESTORER) && 253 ka->sa.sa_restorer) { 254 /* This is the legacy signal stack switching. */ 255 sp = (unsigned long) ka->sa.sa_restorer; 256 } 257 258 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32), 259 &buf_fx, &math_size); 260 *fpstate = (void __user *)sp; 261 262 sp = align_sigframe(sp - frame_size); 263 264 /* 265 * If we are on the alternate signal stack and would overflow it, don't. 266 * Return an always-bogus address instead so we will die with SIGSEGV. 267 */ 268 if (onsigstack && !likely(on_sig_stack(sp))) 269 return (void __user *)-1L; 270 271 /* save i387 and extended state */ 272 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size); 273 if (ret < 0) 274 return (void __user *)-1L; 275 276 return (void __user *)sp; 277 } 278 279 #ifdef CONFIG_X86_32 280 static const struct { 281 u16 poplmovl; 282 u32 val; 283 u16 int80; 284 } __attribute__((packed)) retcode = { 285 0xb858, /* popl %eax; movl $..., %eax */ 286 __NR_sigreturn, 287 0x80cd, /* int $0x80 */ 288 }; 289 290 static const struct { 291 u8 movl; 292 u32 val; 293 u16 int80; 294 u8 pad; 295 } __attribute__((packed)) rt_retcode = { 296 0xb8, /* movl $..., %eax */ 297 __NR_rt_sigreturn, 298 0x80cd, /* int $0x80 */ 299 0 300 }; 301 302 static int 303 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, 304 struct pt_regs *regs) 305 { 306 struct sigframe __user *frame; 307 void __user *restorer; 308 void __user *fp = NULL; 309 310 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 311 312 if (!user_access_begin(frame, sizeof(*frame))) 313 return -EFAULT; 314 315 unsafe_put_user(sig, &frame->sig, Efault); 316 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault); 317 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault); 318 if (current->mm->context.vdso) 319 restorer = current->mm->context.vdso + 320 vdso_image_32.sym___kernel_sigreturn; 321 else 322 restorer = &frame->retcode; 323 if (ksig->ka.sa.sa_flags & SA_RESTORER) 324 restorer = ksig->ka.sa.sa_restorer; 325 326 /* Set up to return from userspace. */ 327 unsafe_put_user(restorer, &frame->pretcode, Efault); 328 329 /* 330 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80 331 * 332 * WE DO NOT USE IT ANY MORE! It's only left here for historical 333 * reasons and because gdb uses it as a signature to notice 334 * signal handler stack frames. 335 */ 336 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault); 337 user_access_end(); 338 339 /* Set up registers for signal handler */ 340 regs->sp = (unsigned long)frame; 341 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 342 regs->ax = (unsigned long)sig; 343 regs->dx = 0; 344 regs->cx = 0; 345 346 regs->ds = __USER_DS; 347 regs->es = __USER_DS; 348 regs->ss = __USER_DS; 349 regs->cs = __USER_CS; 350 351 return 0; 352 353 Efault: 354 user_access_end(); 355 return -EFAULT; 356 } 357 358 static int __setup_rt_frame(int sig, struct ksignal *ksig, 359 sigset_t *set, struct pt_regs *regs) 360 { 361 struct rt_sigframe __user *frame; 362 void __user *restorer; 363 void __user *fp = NULL; 364 365 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 366 367 if (!user_access_begin(frame, sizeof(*frame))) 368 return -EFAULT; 369 370 unsafe_put_user(sig, &frame->sig, Efault); 371 unsafe_put_user(&frame->info, &frame->pinfo, Efault); 372 unsafe_put_user(&frame->uc, &frame->puc, Efault); 373 374 /* Create the ucontext. */ 375 if (static_cpu_has(X86_FEATURE_XSAVE)) 376 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault); 377 else 378 unsafe_put_user(0, &frame->uc.uc_flags, Efault); 379 unsafe_put_user(0, &frame->uc.uc_link, Efault); 380 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 381 382 /* Set up to return from userspace. */ 383 restorer = current->mm->context.vdso + 384 vdso_image_32.sym___kernel_rt_sigreturn; 385 if (ksig->ka.sa.sa_flags & SA_RESTORER) 386 restorer = ksig->ka.sa.sa_restorer; 387 unsafe_put_user(restorer, &frame->pretcode, Efault); 388 389 /* 390 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 391 * 392 * WE DO NOT USE IT ANY MORE! It's only left here for historical 393 * reasons and because gdb uses it as a signature to notice 394 * signal handler stack frames. 395 */ 396 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault); 397 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 398 unsafe_put_sigmask(set, frame, Efault); 399 user_access_end(); 400 401 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 402 return -EFAULT; 403 404 /* Set up registers for signal handler */ 405 regs->sp = (unsigned long)frame; 406 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 407 regs->ax = (unsigned long)sig; 408 regs->dx = (unsigned long)&frame->info; 409 regs->cx = (unsigned long)&frame->uc; 410 411 regs->ds = __USER_DS; 412 regs->es = __USER_DS; 413 regs->ss = __USER_DS; 414 regs->cs = __USER_CS; 415 416 return 0; 417 Efault: 418 user_access_end(); 419 return -EFAULT; 420 } 421 #else /* !CONFIG_X86_32 */ 422 static unsigned long frame_uc_flags(struct pt_regs *regs) 423 { 424 unsigned long flags; 425 426 if (boot_cpu_has(X86_FEATURE_XSAVE)) 427 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS; 428 else 429 flags = UC_SIGCONTEXT_SS; 430 431 if (likely(user_64bit_mode(regs))) 432 flags |= UC_STRICT_RESTORE_SS; 433 434 return flags; 435 } 436 437 static int __setup_rt_frame(int sig, struct ksignal *ksig, 438 sigset_t *set, struct pt_regs *regs) 439 { 440 struct rt_sigframe __user *frame; 441 void __user *fp = NULL; 442 unsigned long uc_flags; 443 444 /* x86-64 should always use SA_RESTORER. */ 445 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 446 return -EFAULT; 447 448 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); 449 uc_flags = frame_uc_flags(regs); 450 451 if (!user_access_begin(frame, sizeof(*frame))) 452 return -EFAULT; 453 454 /* Create the ucontext. */ 455 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 456 unsafe_put_user(0, &frame->uc.uc_link, Efault); 457 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 458 459 /* Set up to return from userspace. If provided, use a stub 460 already in userspace. */ 461 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault); 462 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 463 unsafe_put_sigmask(set, frame, Efault); 464 user_access_end(); 465 466 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 467 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 468 return -EFAULT; 469 } 470 471 /* Set up registers for signal handler */ 472 regs->di = sig; 473 /* In case the signal handler was declared without prototypes */ 474 regs->ax = 0; 475 476 /* This also works for non SA_SIGINFO handlers because they expect the 477 next argument after the signal number on the stack. */ 478 regs->si = (unsigned long)&frame->info; 479 regs->dx = (unsigned long)&frame->uc; 480 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 481 482 regs->sp = (unsigned long)frame; 483 484 /* 485 * Set up the CS and SS registers to run signal handlers in 486 * 64-bit mode, even if the handler happens to be interrupting 487 * 32-bit or 16-bit code. 488 * 489 * SS is subtle. In 64-bit mode, we don't need any particular 490 * SS descriptor, but we do need SS to be valid. It's possible 491 * that the old SS is entirely bogus -- this can happen if the 492 * signal we're trying to deliver is #GP or #SS caused by a bad 493 * SS value. We also have a compatbility issue here: DOSEMU 494 * relies on the contents of the SS register indicating the 495 * SS value at the time of the signal, even though that code in 496 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU 497 * avoids relying on sigreturn to restore SS; instead it uses 498 * a trampoline.) So we do our best: if the old SS was valid, 499 * we keep it. Otherwise we replace it. 500 */ 501 regs->cs = __USER_CS; 502 503 if (unlikely(regs->ss != __USER_DS)) 504 force_valid_ss(regs); 505 506 return 0; 507 508 Efault: 509 user_access_end(); 510 return -EFAULT; 511 } 512 #endif /* CONFIG_X86_32 */ 513 514 static int x32_setup_rt_frame(struct ksignal *ksig, 515 compat_sigset_t *set, 516 struct pt_regs *regs) 517 { 518 #ifdef CONFIG_X86_X32_ABI 519 struct rt_sigframe_x32 __user *frame; 520 unsigned long uc_flags; 521 void __user *restorer; 522 void __user *fp = NULL; 523 524 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 525 return -EFAULT; 526 527 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 528 529 uc_flags = frame_uc_flags(regs); 530 531 if (!user_access_begin(frame, sizeof(*frame))) 532 return -EFAULT; 533 534 /* Create the ucontext. */ 535 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 536 unsafe_put_user(0, &frame->uc.uc_link, Efault); 537 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 538 unsafe_put_user(0, &frame->uc.uc__pad0, Efault); 539 restorer = ksig->ka.sa.sa_restorer; 540 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault); 541 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 542 unsafe_put_sigmask(set, frame, Efault); 543 user_access_end(); 544 545 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 546 if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true)) 547 return -EFAULT; 548 } 549 550 /* Set up registers for signal handler */ 551 regs->sp = (unsigned long) frame; 552 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 553 554 /* We use the x32 calling convention here... */ 555 regs->di = ksig->sig; 556 regs->si = (unsigned long) &frame->info; 557 regs->dx = (unsigned long) &frame->uc; 558 559 loadsegment(ds, __USER_DS); 560 loadsegment(es, __USER_DS); 561 562 regs->cs = __USER_CS; 563 regs->ss = __USER_DS; 564 #endif /* CONFIG_X86_X32_ABI */ 565 566 return 0; 567 #ifdef CONFIG_X86_X32_ABI 568 Efault: 569 user_access_end(); 570 return -EFAULT; 571 #endif 572 } 573 574 /* 575 * Do a signal return; undo the signal stack. 576 */ 577 #ifdef CONFIG_X86_32 578 SYSCALL_DEFINE0(sigreturn) 579 { 580 struct pt_regs *regs = current_pt_regs(); 581 struct sigframe __user *frame; 582 sigset_t set; 583 584 frame = (struct sigframe __user *)(regs->sp - 8); 585 586 if (!access_ok(frame, sizeof(*frame))) 587 goto badframe; 588 if (__get_user(set.sig[0], &frame->sc.oldmask) || 589 __get_user(set.sig[1], &frame->extramask[0])) 590 goto badframe; 591 592 set_current_blocked(&set); 593 594 /* 595 * x86_32 has no uc_flags bits relevant to restore_sigcontext. 596 * Save a few cycles by skipping the __get_user. 597 */ 598 if (restore_sigcontext(regs, &frame->sc, 0)) 599 goto badframe; 600 return regs->ax; 601 602 badframe: 603 signal_fault(regs, frame, "sigreturn"); 604 605 return 0; 606 } 607 #endif /* CONFIG_X86_32 */ 608 609 SYSCALL_DEFINE0(rt_sigreturn) 610 { 611 struct pt_regs *regs = current_pt_regs(); 612 struct rt_sigframe __user *frame; 613 sigset_t set; 614 unsigned long uc_flags; 615 616 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 617 if (!access_ok(frame, sizeof(*frame))) 618 goto badframe; 619 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask)) 620 goto badframe; 621 if (__get_user(uc_flags, &frame->uc.uc_flags)) 622 goto badframe; 623 624 set_current_blocked(&set); 625 626 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 627 goto badframe; 628 629 if (restore_altstack(&frame->uc.uc_stack)) 630 goto badframe; 631 632 return regs->ax; 633 634 badframe: 635 signal_fault(regs, frame, "rt_sigreturn"); 636 return 0; 637 } 638 639 static inline int is_ia32_compat_frame(struct ksignal *ksig) 640 { 641 return IS_ENABLED(CONFIG_IA32_EMULATION) && 642 ksig->ka.sa.sa_flags & SA_IA32_ABI; 643 } 644 645 static inline int is_ia32_frame(struct ksignal *ksig) 646 { 647 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); 648 } 649 650 static inline int is_x32_frame(struct ksignal *ksig) 651 { 652 return IS_ENABLED(CONFIG_X86_X32_ABI) && 653 ksig->ka.sa.sa_flags & SA_X32_ABI; 654 } 655 656 static int 657 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 658 { 659 int usig = ksig->sig; 660 sigset_t *set = sigmask_to_save(); 661 compat_sigset_t *cset = (compat_sigset_t *) set; 662 663 /* Perform fixup for the pre-signal frame. */ 664 rseq_signal_deliver(ksig, regs); 665 666 /* Set up the stack frame */ 667 if (is_ia32_frame(ksig)) { 668 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 669 return ia32_setup_rt_frame(usig, ksig, cset, regs); 670 else 671 return ia32_setup_frame(usig, ksig, cset, regs); 672 } else if (is_x32_frame(ksig)) { 673 return x32_setup_rt_frame(ksig, cset, regs); 674 } else { 675 return __setup_rt_frame(ksig->sig, ksig, set, regs); 676 } 677 } 678 679 static void 680 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 681 { 682 bool stepping, failed; 683 struct fpu *fpu = ¤t->thread.fpu; 684 685 if (v8086_mode(regs)) 686 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); 687 688 /* Are we from a system call? */ 689 if (syscall_get_nr(current, regs) >= 0) { 690 /* If so, check system call restarting.. */ 691 switch (syscall_get_error(current, regs)) { 692 case -ERESTART_RESTARTBLOCK: 693 case -ERESTARTNOHAND: 694 regs->ax = -EINTR; 695 break; 696 697 case -ERESTARTSYS: 698 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 699 regs->ax = -EINTR; 700 break; 701 } 702 /* fallthrough */ 703 case -ERESTARTNOINTR: 704 regs->ax = regs->orig_ax; 705 regs->ip -= 2; 706 break; 707 } 708 } 709 710 /* 711 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now 712 * so that register information in the sigcontext is correct and 713 * then notify the tracer before entering the signal handler. 714 */ 715 stepping = test_thread_flag(TIF_SINGLESTEP); 716 if (stepping) 717 user_disable_single_step(current); 718 719 failed = (setup_rt_frame(ksig, regs) < 0); 720 if (!failed) { 721 /* 722 * Clear the direction flag as per the ABI for function entry. 723 * 724 * Clear RF when entering the signal handler, because 725 * it might disable possible debug exception from the 726 * signal handler. 727 * 728 * Clear TF for the case when it wasn't set by debugger to 729 * avoid the recursive send_sigtrap() in SIGTRAP handler. 730 */ 731 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); 732 /* 733 * Ensure the signal handler starts with the new fpu state. 734 */ 735 fpu__clear(fpu); 736 } 737 signal_setup_done(failed, ksig, stepping); 738 } 739 740 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) 741 { 742 /* 743 * This function is fundamentally broken as currently 744 * implemented. 745 * 746 * The idea is that we want to trigger a call to the 747 * restart_block() syscall and that we want in_ia32_syscall(), 748 * in_x32_syscall(), etc. to match whatever they were in the 749 * syscall being restarted. We assume that the syscall 750 * instruction at (regs->ip - 2) matches whatever syscall 751 * instruction we used to enter in the first place. 752 * 753 * The problem is that we can get here when ptrace pokes 754 * syscall-like values into regs even if we're not in a syscall 755 * at all. 756 * 757 * For now, we maintain historical behavior and guess based on 758 * stored state. We could do better by saving the actual 759 * syscall arch in restart_block or (with caveats on x32) by 760 * checking if regs->ip points to 'int $0x80'. The current 761 * behavior is incorrect if a tracer has a different bitness 762 * than the tracee. 763 */ 764 #ifdef CONFIG_IA32_EMULATION 765 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED)) 766 return __NR_ia32_restart_syscall; 767 #endif 768 #ifdef CONFIG_X86_X32_ABI 769 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); 770 #else 771 return __NR_restart_syscall; 772 #endif 773 } 774 775 /* 776 * Note that 'init' is a special process: it doesn't get signals it doesn't 777 * want to handle. Thus you cannot kill init even with a SIGKILL even by 778 * mistake. 779 */ 780 void do_signal(struct pt_regs *regs) 781 { 782 struct ksignal ksig; 783 784 if (get_signal(&ksig)) { 785 /* Whee! Actually deliver the signal. */ 786 handle_signal(&ksig, regs); 787 return; 788 } 789 790 /* Did we come from a system call? */ 791 if (syscall_get_nr(current, regs) >= 0) { 792 /* Restart the system call - no handlers present */ 793 switch (syscall_get_error(current, regs)) { 794 case -ERESTARTNOHAND: 795 case -ERESTARTSYS: 796 case -ERESTARTNOINTR: 797 regs->ax = regs->orig_ax; 798 regs->ip -= 2; 799 break; 800 801 case -ERESTART_RESTARTBLOCK: 802 regs->ax = get_nr_restart_syscall(regs); 803 regs->ip -= 2; 804 break; 805 } 806 } 807 808 /* 809 * If there's no signal to deliver, we just put the saved sigmask 810 * back. 811 */ 812 restore_saved_sigmask(); 813 } 814 815 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 816 { 817 struct task_struct *me = current; 818 819 if (show_unhandled_signals && printk_ratelimit()) { 820 printk("%s" 821 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 822 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, 823 me->comm, me->pid, where, frame, 824 regs->ip, regs->sp, regs->orig_ax); 825 print_vma_addr(KERN_CONT " in ", regs->ip); 826 pr_cont("\n"); 827 } 828 829 force_sig(SIGSEGV); 830 } 831 832 #ifdef CONFIG_X86_X32_ABI 833 COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn) 834 { 835 struct pt_regs *regs = current_pt_regs(); 836 struct rt_sigframe_x32 __user *frame; 837 sigset_t set; 838 unsigned long uc_flags; 839 840 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); 841 842 if (!access_ok(frame, sizeof(*frame))) 843 goto badframe; 844 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask)) 845 goto badframe; 846 if (__get_user(uc_flags, &frame->uc.uc_flags)) 847 goto badframe; 848 849 set_current_blocked(&set); 850 851 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 852 goto badframe; 853 854 if (compat_restore_altstack(&frame->uc.uc_stack)) 855 goto badframe; 856 857 return regs->ax; 858 859 badframe: 860 signal_fault(regs, frame, "x32 rt_sigreturn"); 861 return 0; 862 } 863 #endif 864