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/entry-common.h> 29 #include <linux/syscalls.h> 30 31 #include <asm/processor.h> 32 #include <asm/ucontext.h> 33 #include <asm/fpu/internal.h> 34 #include <asm/fpu/signal.h> 35 #include <asm/vdso.h> 36 #include <asm/mce.h> 37 #include <asm/sighandling.h> 38 #include <asm/vm86.h> 39 40 #ifdef CONFIG_X86_64 41 #include <linux/compat.h> 42 #include <asm/proto.h> 43 #include <asm/ia32_unistd.h> 44 #endif /* CONFIG_X86_64 */ 45 46 #include <asm/syscall.h> 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 #define unsafe_put_sigmask(set, frame, label) \ 207 unsafe_put_user(*(__u64 *)(set), \ 208 (__u64 __user *)&(frame)->uc.uc_sigmask, \ 209 label) 210 211 /* 212 * Set up a signal frame. 213 */ 214 215 /* 216 * Determine which stack to use.. 217 */ 218 static unsigned long align_sigframe(unsigned long sp) 219 { 220 #ifdef CONFIG_X86_32 221 /* 222 * Align the stack pointer according to the i386 ABI, 223 * i.e. so that on function entry ((sp + 4) & 15) == 0. 224 */ 225 sp = ((sp + 4) & -16ul) - 4; 226 #else /* !CONFIG_X86_32 */ 227 sp = round_down(sp, 16) - 8; 228 #endif 229 return sp; 230 } 231 232 static void __user * 233 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, 234 void __user **fpstate) 235 { 236 /* Default to using normal stack */ 237 unsigned long math_size = 0; 238 unsigned long sp = regs->sp; 239 unsigned long buf_fx = 0; 240 int onsigstack = on_sig_stack(sp); 241 int ret; 242 243 /* redzone */ 244 if (IS_ENABLED(CONFIG_X86_64)) 245 sp -= 128; 246 247 /* This is the X/Open sanctioned signal stack switching. */ 248 if (ka->sa.sa_flags & SA_ONSTACK) { 249 if (sas_ss_flags(sp) == 0) 250 sp = current->sas_ss_sp + current->sas_ss_size; 251 } else if (IS_ENABLED(CONFIG_X86_32) && 252 !onsigstack && 253 regs->ss != __USER_DS && 254 !(ka->sa.sa_flags & SA_RESTORER) && 255 ka->sa.sa_restorer) { 256 /* This is the legacy signal stack switching. */ 257 sp = (unsigned long) ka->sa.sa_restorer; 258 } 259 260 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32), 261 &buf_fx, &math_size); 262 *fpstate = (void __user *)sp; 263 264 sp = align_sigframe(sp - frame_size); 265 266 /* 267 * If we are on the alternate signal stack and would overflow it, don't. 268 * Return an always-bogus address instead so we will die with SIGSEGV. 269 */ 270 if (onsigstack && !likely(on_sig_stack(sp))) 271 return (void __user *)-1L; 272 273 /* save i387 and extended state */ 274 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size); 275 if (ret < 0) 276 return (void __user *)-1L; 277 278 return (void __user *)sp; 279 } 280 281 #ifdef CONFIG_X86_32 282 static const struct { 283 u16 poplmovl; 284 u32 val; 285 u16 int80; 286 } __attribute__((packed)) retcode = { 287 0xb858, /* popl %eax; movl $..., %eax */ 288 __NR_sigreturn, 289 0x80cd, /* int $0x80 */ 290 }; 291 292 static const struct { 293 u8 movl; 294 u32 val; 295 u16 int80; 296 u8 pad; 297 } __attribute__((packed)) rt_retcode = { 298 0xb8, /* movl $..., %eax */ 299 __NR_rt_sigreturn, 300 0x80cd, /* int $0x80 */ 301 0 302 }; 303 304 static int 305 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, 306 struct pt_regs *regs) 307 { 308 struct sigframe __user *frame; 309 void __user *restorer; 310 void __user *fp = NULL; 311 312 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 313 314 if (!user_access_begin(frame, sizeof(*frame))) 315 return -EFAULT; 316 317 unsafe_put_user(sig, &frame->sig, Efault); 318 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault); 319 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault); 320 if (current->mm->context.vdso) 321 restorer = current->mm->context.vdso + 322 vdso_image_32.sym___kernel_sigreturn; 323 else 324 restorer = &frame->retcode; 325 if (ksig->ka.sa.sa_flags & SA_RESTORER) 326 restorer = ksig->ka.sa.sa_restorer; 327 328 /* Set up to return from userspace. */ 329 unsafe_put_user(restorer, &frame->pretcode, Efault); 330 331 /* 332 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80 333 * 334 * WE DO NOT USE IT ANY MORE! It's only left here for historical 335 * reasons and because gdb uses it as a signature to notice 336 * signal handler stack frames. 337 */ 338 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault); 339 user_access_end(); 340 341 /* Set up registers for signal handler */ 342 regs->sp = (unsigned long)frame; 343 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 344 regs->ax = (unsigned long)sig; 345 regs->dx = 0; 346 regs->cx = 0; 347 348 regs->ds = __USER_DS; 349 regs->es = __USER_DS; 350 regs->ss = __USER_DS; 351 regs->cs = __USER_CS; 352 353 return 0; 354 355 Efault: 356 user_access_end(); 357 return -EFAULT; 358 } 359 360 static int __setup_rt_frame(int sig, struct ksignal *ksig, 361 sigset_t *set, struct pt_regs *regs) 362 { 363 struct rt_sigframe __user *frame; 364 void __user *restorer; 365 void __user *fp = NULL; 366 367 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 368 369 if (!user_access_begin(frame, sizeof(*frame))) 370 return -EFAULT; 371 372 unsafe_put_user(sig, &frame->sig, Efault); 373 unsafe_put_user(&frame->info, &frame->pinfo, Efault); 374 unsafe_put_user(&frame->uc, &frame->puc, Efault); 375 376 /* Create the ucontext. */ 377 if (static_cpu_has(X86_FEATURE_XSAVE)) 378 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault); 379 else 380 unsafe_put_user(0, &frame->uc.uc_flags, Efault); 381 unsafe_put_user(0, &frame->uc.uc_link, Efault); 382 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 383 384 /* Set up to return from userspace. */ 385 restorer = current->mm->context.vdso + 386 vdso_image_32.sym___kernel_rt_sigreturn; 387 if (ksig->ka.sa.sa_flags & SA_RESTORER) 388 restorer = ksig->ka.sa.sa_restorer; 389 unsafe_put_user(restorer, &frame->pretcode, Efault); 390 391 /* 392 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 393 * 394 * WE DO NOT USE IT ANY MORE! It's only left here for historical 395 * reasons and because gdb uses it as a signature to notice 396 * signal handler stack frames. 397 */ 398 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault); 399 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 400 unsafe_put_sigmask(set, frame, Efault); 401 user_access_end(); 402 403 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 404 return -EFAULT; 405 406 /* Set up registers for signal handler */ 407 regs->sp = (unsigned long)frame; 408 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 409 regs->ax = (unsigned long)sig; 410 regs->dx = (unsigned long)&frame->info; 411 regs->cx = (unsigned long)&frame->uc; 412 413 regs->ds = __USER_DS; 414 regs->es = __USER_DS; 415 regs->ss = __USER_DS; 416 regs->cs = __USER_CS; 417 418 return 0; 419 Efault: 420 user_access_end(); 421 return -EFAULT; 422 } 423 #else /* !CONFIG_X86_32 */ 424 static unsigned long frame_uc_flags(struct pt_regs *regs) 425 { 426 unsigned long flags; 427 428 if (boot_cpu_has(X86_FEATURE_XSAVE)) 429 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS; 430 else 431 flags = UC_SIGCONTEXT_SS; 432 433 if (likely(user_64bit_mode(regs))) 434 flags |= UC_STRICT_RESTORE_SS; 435 436 return flags; 437 } 438 439 static int __setup_rt_frame(int sig, struct ksignal *ksig, 440 sigset_t *set, struct pt_regs *regs) 441 { 442 struct rt_sigframe __user *frame; 443 void __user *fp = NULL; 444 unsigned long uc_flags; 445 446 /* x86-64 should always use SA_RESTORER. */ 447 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 448 return -EFAULT; 449 450 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); 451 uc_flags = frame_uc_flags(regs); 452 453 if (!user_access_begin(frame, sizeof(*frame))) 454 return -EFAULT; 455 456 /* Create the ucontext. */ 457 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 458 unsafe_put_user(0, &frame->uc.uc_link, Efault); 459 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 460 461 /* Set up to return from userspace. If provided, use a stub 462 already in userspace. */ 463 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault); 464 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 465 unsafe_put_sigmask(set, frame, Efault); 466 user_access_end(); 467 468 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 469 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 470 return -EFAULT; 471 } 472 473 /* Set up registers for signal handler */ 474 regs->di = sig; 475 /* In case the signal handler was declared without prototypes */ 476 regs->ax = 0; 477 478 /* This also works for non SA_SIGINFO handlers because they expect the 479 next argument after the signal number on the stack. */ 480 regs->si = (unsigned long)&frame->info; 481 regs->dx = (unsigned long)&frame->uc; 482 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 483 484 regs->sp = (unsigned long)frame; 485 486 /* 487 * Set up the CS and SS registers to run signal handlers in 488 * 64-bit mode, even if the handler happens to be interrupting 489 * 32-bit or 16-bit code. 490 * 491 * SS is subtle. In 64-bit mode, we don't need any particular 492 * SS descriptor, but we do need SS to be valid. It's possible 493 * that the old SS is entirely bogus -- this can happen if the 494 * signal we're trying to deliver is #GP or #SS caused by a bad 495 * SS value. We also have a compatbility issue here: DOSEMU 496 * relies on the contents of the SS register indicating the 497 * SS value at the time of the signal, even though that code in 498 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU 499 * avoids relying on sigreturn to restore SS; instead it uses 500 * a trampoline.) So we do our best: if the old SS was valid, 501 * we keep it. Otherwise we replace it. 502 */ 503 regs->cs = __USER_CS; 504 505 if (unlikely(regs->ss != __USER_DS)) 506 force_valid_ss(regs); 507 508 return 0; 509 510 Efault: 511 user_access_end(); 512 return -EFAULT; 513 } 514 #endif /* CONFIG_X86_32 */ 515 516 #ifdef CONFIG_X86_X32_ABI 517 static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to, 518 const struct kernel_siginfo *from) 519 { 520 struct compat_siginfo new; 521 522 copy_siginfo_to_external32(&new, from); 523 if (from->si_signo == SIGCHLD) { 524 new._sifields._sigchld_x32._utime = from->si_utime; 525 new._sifields._sigchld_x32._stime = from->si_stime; 526 } 527 if (copy_to_user(to, &new, sizeof(struct compat_siginfo))) 528 return -EFAULT; 529 return 0; 530 } 531 532 int copy_siginfo_to_user32(struct compat_siginfo __user *to, 533 const struct kernel_siginfo *from) 534 { 535 if (in_x32_syscall()) 536 return x32_copy_siginfo_to_user(to, from); 537 return __copy_siginfo_to_user32(to, from); 538 } 539 #endif /* CONFIG_X86_X32_ABI */ 540 541 static int x32_setup_rt_frame(struct ksignal *ksig, 542 compat_sigset_t *set, 543 struct pt_regs *regs) 544 { 545 #ifdef CONFIG_X86_X32_ABI 546 struct rt_sigframe_x32 __user *frame; 547 unsigned long uc_flags; 548 void __user *restorer; 549 void __user *fp = NULL; 550 551 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 552 return -EFAULT; 553 554 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 555 556 uc_flags = frame_uc_flags(regs); 557 558 if (!user_access_begin(frame, sizeof(*frame))) 559 return -EFAULT; 560 561 /* Create the ucontext. */ 562 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 563 unsafe_put_user(0, &frame->uc.uc_link, Efault); 564 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 565 unsafe_put_user(0, &frame->uc.uc__pad0, Efault); 566 restorer = ksig->ka.sa.sa_restorer; 567 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault); 568 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 569 unsafe_put_sigmask(set, frame, Efault); 570 user_access_end(); 571 572 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 573 if (x32_copy_siginfo_to_user(&frame->info, &ksig->info)) 574 return -EFAULT; 575 } 576 577 /* Set up registers for signal handler */ 578 regs->sp = (unsigned long) frame; 579 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 580 581 /* We use the x32 calling convention here... */ 582 regs->di = ksig->sig; 583 regs->si = (unsigned long) &frame->info; 584 regs->dx = (unsigned long) &frame->uc; 585 586 loadsegment(ds, __USER_DS); 587 loadsegment(es, __USER_DS); 588 589 regs->cs = __USER_CS; 590 regs->ss = __USER_DS; 591 #endif /* CONFIG_X86_X32_ABI */ 592 593 return 0; 594 #ifdef CONFIG_X86_X32_ABI 595 Efault: 596 user_access_end(); 597 return -EFAULT; 598 #endif 599 } 600 601 /* 602 * Do a signal return; undo the signal stack. 603 */ 604 #ifdef CONFIG_X86_32 605 SYSCALL_DEFINE0(sigreturn) 606 { 607 struct pt_regs *regs = current_pt_regs(); 608 struct sigframe __user *frame; 609 sigset_t set; 610 611 frame = (struct sigframe __user *)(regs->sp - 8); 612 613 if (!access_ok(frame, sizeof(*frame))) 614 goto badframe; 615 if (__get_user(set.sig[0], &frame->sc.oldmask) || 616 __get_user(set.sig[1], &frame->extramask[0])) 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 SYSCALL_DEFINE0(rt_sigreturn) 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(frame, sizeof(*frame))) 645 goto badframe; 646 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask)) 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 /* Perform fixup for the pre-signal frame. */ 691 rseq_signal_deliver(ksig, regs); 692 693 /* Set up the stack frame */ 694 if (is_ia32_frame(ksig)) { 695 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 696 return ia32_setup_rt_frame(usig, ksig, cset, regs); 697 else 698 return ia32_setup_frame(usig, ksig, cset, regs); 699 } else if (is_x32_frame(ksig)) { 700 return x32_setup_rt_frame(ksig, cset, regs); 701 } else { 702 return __setup_rt_frame(ksig->sig, ksig, set, regs); 703 } 704 } 705 706 static void 707 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 708 { 709 bool stepping, failed; 710 struct fpu *fpu = ¤t->thread.fpu; 711 712 if (v8086_mode(regs)) 713 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); 714 715 /* Are we from a system call? */ 716 if (syscall_get_nr(current, regs) >= 0) { 717 /* If so, check system call restarting.. */ 718 switch (syscall_get_error(current, regs)) { 719 case -ERESTART_RESTARTBLOCK: 720 case -ERESTARTNOHAND: 721 regs->ax = -EINTR; 722 break; 723 724 case -ERESTARTSYS: 725 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 726 regs->ax = -EINTR; 727 break; 728 } 729 /* fallthrough */ 730 case -ERESTARTNOINTR: 731 regs->ax = regs->orig_ax; 732 regs->ip -= 2; 733 break; 734 } 735 } 736 737 /* 738 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now 739 * so that register information in the sigcontext is correct and 740 * then notify the tracer before entering the signal handler. 741 */ 742 stepping = test_thread_flag(TIF_SINGLESTEP); 743 if (stepping) 744 user_disable_single_step(current); 745 746 failed = (setup_rt_frame(ksig, regs) < 0); 747 if (!failed) { 748 /* 749 * Clear the direction flag as per the ABI for function entry. 750 * 751 * Clear RF when entering the signal handler, because 752 * it might disable possible debug exception from the 753 * signal handler. 754 * 755 * Clear TF for the case when it wasn't set by debugger to 756 * avoid the recursive send_sigtrap() in SIGTRAP handler. 757 */ 758 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); 759 /* 760 * Ensure the signal handler starts with the new fpu state. 761 */ 762 fpu__clear_user_states(fpu); 763 } 764 signal_setup_done(failed, ksig, stepping); 765 } 766 767 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) 768 { 769 /* 770 * This function is fundamentally broken as currently 771 * implemented. 772 * 773 * The idea is that we want to trigger a call to the 774 * restart_block() syscall and that we want in_ia32_syscall(), 775 * in_x32_syscall(), etc. to match whatever they were in the 776 * syscall being restarted. We assume that the syscall 777 * instruction at (regs->ip - 2) matches whatever syscall 778 * instruction we used to enter in the first place. 779 * 780 * The problem is that we can get here when ptrace pokes 781 * syscall-like values into regs even if we're not in a syscall 782 * at all. 783 * 784 * For now, we maintain historical behavior and guess based on 785 * stored state. We could do better by saving the actual 786 * syscall arch in restart_block or (with caveats on x32) by 787 * checking if regs->ip points to 'int $0x80'. The current 788 * behavior is incorrect if a tracer has a different bitness 789 * than the tracee. 790 */ 791 #ifdef CONFIG_IA32_EMULATION 792 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED)) 793 return __NR_ia32_restart_syscall; 794 #endif 795 #ifdef CONFIG_X86_X32_ABI 796 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); 797 #else 798 return __NR_restart_syscall; 799 #endif 800 } 801 802 /* 803 * Note that 'init' is a special process: it doesn't get signals it doesn't 804 * want to handle. Thus you cannot kill init even with a SIGKILL even by 805 * mistake. 806 */ 807 void arch_do_signal(struct pt_regs *regs) 808 { 809 struct ksignal ksig; 810 811 if (get_signal(&ksig)) { 812 /* Whee! Actually deliver the signal. */ 813 handle_signal(&ksig, regs); 814 return; 815 } 816 817 /* Did we come from a system call? */ 818 if (syscall_get_nr(current, regs) >= 0) { 819 /* Restart the system call - no handlers present */ 820 switch (syscall_get_error(current, regs)) { 821 case -ERESTARTNOHAND: 822 case -ERESTARTSYS: 823 case -ERESTARTNOINTR: 824 regs->ax = regs->orig_ax; 825 regs->ip -= 2; 826 break; 827 828 case -ERESTART_RESTARTBLOCK: 829 regs->ax = get_nr_restart_syscall(regs); 830 regs->ip -= 2; 831 break; 832 } 833 } 834 835 /* 836 * If there's no signal to deliver, we just put the saved sigmask 837 * back. 838 */ 839 restore_saved_sigmask(); 840 } 841 842 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 843 { 844 struct task_struct *me = current; 845 846 if (show_unhandled_signals && printk_ratelimit()) { 847 printk("%s" 848 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 849 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, 850 me->comm, me->pid, where, frame, 851 regs->ip, regs->sp, regs->orig_ax); 852 print_vma_addr(KERN_CONT " in ", regs->ip); 853 pr_cont("\n"); 854 } 855 856 force_sig(SIGSEGV); 857 } 858 859 #ifdef CONFIG_X86_X32_ABI 860 COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn) 861 { 862 struct pt_regs *regs = current_pt_regs(); 863 struct rt_sigframe_x32 __user *frame; 864 sigset_t set; 865 unsigned long uc_flags; 866 867 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); 868 869 if (!access_ok(frame, sizeof(*frame))) 870 goto badframe; 871 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask)) 872 goto badframe; 873 if (__get_user(uc_flags, &frame->uc.uc_flags)) 874 goto badframe; 875 876 set_current_blocked(&set); 877 878 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 879 goto badframe; 880 881 if (compat_restore_altstack(&frame->uc.uc_stack)) 882 goto badframe; 883 884 return regs->ax; 885 886 badframe: 887 signal_fault(regs, frame, "x32 rt_sigreturn"); 888 return 0; 889 } 890 #endif 891