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 <linux/compat.h> 41 #include <asm/proto.h> 42 #include <asm/ia32_unistd.h> 43 #endif /* CONFIG_X86_64 */ 44 45 #include <asm/syscall.h> 46 #include <asm/sigframe.h> 47 #include <asm/signal.h> 48 49 #ifdef CONFIG_X86_64 50 /* 51 * If regs->ss will cause an IRET fault, change it. Otherwise leave it 52 * alone. Using this generally makes no sense unless 53 * user_64bit_mode(regs) would return true. 54 */ 55 static void force_valid_ss(struct pt_regs *regs) 56 { 57 u32 ar; 58 asm volatile ("lar %[old_ss], %[ar]\n\t" 59 "jz 1f\n\t" /* If invalid: */ 60 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */ 61 "1:" 62 : [ar] "=r" (ar) 63 : [old_ss] "rm" ((u16)regs->ss)); 64 65 /* 66 * For a valid 64-bit user context, we need DPL 3, type 67 * read-write data or read-write exp-down data, and S and P 68 * set. We can't use VERW because VERW doesn't check the 69 * P bit. 70 */ 71 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK; 72 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) && 73 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN)) 74 regs->ss = __USER_DS; 75 } 76 # define CONTEXT_COPY_SIZE offsetof(struct sigcontext, reserved1) 77 #else 78 # define CONTEXT_COPY_SIZE sizeof(struct sigcontext) 79 #endif 80 81 static int restore_sigcontext(struct pt_regs *regs, 82 struct sigcontext __user *usc, 83 unsigned long uc_flags) 84 { 85 struct sigcontext sc; 86 87 /* Always make any pending restarted system calls return -EINTR */ 88 current->restart_block.fn = do_no_restart_syscall; 89 90 if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE)) 91 return -EFAULT; 92 93 #ifdef CONFIG_X86_32 94 set_user_gs(regs, sc.gs); 95 regs->fs = sc.fs; 96 regs->es = sc.es; 97 regs->ds = sc.ds; 98 #endif /* CONFIG_X86_32 */ 99 100 regs->bx = sc.bx; 101 regs->cx = sc.cx; 102 regs->dx = sc.dx; 103 regs->si = sc.si; 104 regs->di = sc.di; 105 regs->bp = sc.bp; 106 regs->ax = sc.ax; 107 regs->sp = sc.sp; 108 regs->ip = sc.ip; 109 110 #ifdef CONFIG_X86_64 111 regs->r8 = sc.r8; 112 regs->r9 = sc.r9; 113 regs->r10 = sc.r10; 114 regs->r11 = sc.r11; 115 regs->r12 = sc.r12; 116 regs->r13 = sc.r13; 117 regs->r14 = sc.r14; 118 regs->r15 = sc.r15; 119 #endif /* CONFIG_X86_64 */ 120 121 /* Get CS/SS and force CPL3 */ 122 regs->cs = sc.cs | 0x03; 123 regs->ss = sc.ss | 0x03; 124 125 regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS); 126 /* disable syscall checks */ 127 regs->orig_ax = -1; 128 129 #ifdef CONFIG_X86_64 130 /* 131 * Fix up SS if needed for the benefit of old DOSEMU and 132 * CRIU. 133 */ 134 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs))) 135 force_valid_ss(regs); 136 #endif 137 138 return fpu__restore_sig((void __user *)sc.fpstate, 139 IS_ENABLED(CONFIG_X86_32)); 140 } 141 142 static __always_inline int 143 __unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate, 144 struct pt_regs *regs, unsigned long mask) 145 { 146 #ifdef CONFIG_X86_32 147 unsafe_put_user(get_user_gs(regs), 148 (unsigned int __user *)&sc->gs, Efault); 149 unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault); 150 unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault); 151 unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault); 152 #endif /* CONFIG_X86_32 */ 153 154 unsafe_put_user(regs->di, &sc->di, Efault); 155 unsafe_put_user(regs->si, &sc->si, Efault); 156 unsafe_put_user(regs->bp, &sc->bp, Efault); 157 unsafe_put_user(regs->sp, &sc->sp, Efault); 158 unsafe_put_user(regs->bx, &sc->bx, Efault); 159 unsafe_put_user(regs->dx, &sc->dx, Efault); 160 unsafe_put_user(regs->cx, &sc->cx, Efault); 161 unsafe_put_user(regs->ax, &sc->ax, Efault); 162 #ifdef CONFIG_X86_64 163 unsafe_put_user(regs->r8, &sc->r8, Efault); 164 unsafe_put_user(regs->r9, &sc->r9, Efault); 165 unsafe_put_user(regs->r10, &sc->r10, Efault); 166 unsafe_put_user(regs->r11, &sc->r11, Efault); 167 unsafe_put_user(regs->r12, &sc->r12, Efault); 168 unsafe_put_user(regs->r13, &sc->r13, Efault); 169 unsafe_put_user(regs->r14, &sc->r14, Efault); 170 unsafe_put_user(regs->r15, &sc->r15, Efault); 171 #endif /* CONFIG_X86_64 */ 172 173 unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault); 174 unsafe_put_user(current->thread.error_code, &sc->err, Efault); 175 unsafe_put_user(regs->ip, &sc->ip, Efault); 176 #ifdef CONFIG_X86_32 177 unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault); 178 unsafe_put_user(regs->flags, &sc->flags, Efault); 179 unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault); 180 unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault); 181 #else /* !CONFIG_X86_32 */ 182 unsafe_put_user(regs->flags, &sc->flags, Efault); 183 unsafe_put_user(regs->cs, &sc->cs, Efault); 184 unsafe_put_user(0, &sc->gs, Efault); 185 unsafe_put_user(0, &sc->fs, Efault); 186 unsafe_put_user(regs->ss, &sc->ss, Efault); 187 #endif /* CONFIG_X86_32 */ 188 189 unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault); 190 191 /* non-iBCS2 extensions.. */ 192 unsafe_put_user(mask, &sc->oldmask, Efault); 193 unsafe_put_user(current->thread.cr2, &sc->cr2, Efault); 194 return 0; 195 Efault: 196 return -EFAULT; 197 } 198 199 #define unsafe_put_sigcontext(sc, fp, regs, set, label) \ 200 do { \ 201 if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \ 202 goto label; \ 203 } while(0); 204 205 #define unsafe_put_sigmask(set, frame, label) \ 206 unsafe_put_user(*(__u64 *)(set), \ 207 (__u64 __user *)&(frame)->uc.uc_sigmask, \ 208 label) 209 210 /* 211 * Set up a signal frame. 212 */ 213 214 /* 215 * Determine which stack to use.. 216 */ 217 static unsigned long align_sigframe(unsigned long sp) 218 { 219 #ifdef CONFIG_X86_32 220 /* 221 * Align the stack pointer according to the i386 ABI, 222 * i.e. so that on function entry ((sp + 4) & 15) == 0. 223 */ 224 sp = ((sp + 4) & -16ul) - 4; 225 #else /* !CONFIG_X86_32 */ 226 sp = round_down(sp, 16) - 8; 227 #endif 228 return sp; 229 } 230 231 static void __user * 232 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, 233 void __user **fpstate) 234 { 235 /* Default to using normal stack */ 236 unsigned long math_size = 0; 237 unsigned long sp = regs->sp; 238 unsigned long buf_fx = 0; 239 int onsigstack = on_sig_stack(sp); 240 int ret; 241 242 /* redzone */ 243 if (IS_ENABLED(CONFIG_X86_64)) 244 sp -= 128; 245 246 /* This is the X/Open sanctioned signal stack switching. */ 247 if (ka->sa.sa_flags & SA_ONSTACK) { 248 if (sas_ss_flags(sp) == 0) 249 sp = current->sas_ss_sp + current->sas_ss_size; 250 } else if (IS_ENABLED(CONFIG_X86_32) && 251 !onsigstack && 252 regs->ss != __USER_DS && 253 !(ka->sa.sa_flags & SA_RESTORER) && 254 ka->sa.sa_restorer) { 255 /* This is the legacy signal stack switching. */ 256 sp = (unsigned long) ka->sa.sa_restorer; 257 } 258 259 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32), 260 &buf_fx, &math_size); 261 *fpstate = (void __user *)sp; 262 263 sp = align_sigframe(sp - frame_size); 264 265 /* 266 * If we are on the alternate signal stack and would overflow it, don't. 267 * Return an always-bogus address instead so we will die with SIGSEGV. 268 */ 269 if (onsigstack && !likely(on_sig_stack(sp))) 270 return (void __user *)-1L; 271 272 /* save i387 and extended state */ 273 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size); 274 if (ret < 0) 275 return (void __user *)-1L; 276 277 return (void __user *)sp; 278 } 279 280 #ifdef CONFIG_X86_32 281 static const struct { 282 u16 poplmovl; 283 u32 val; 284 u16 int80; 285 } __attribute__((packed)) retcode = { 286 0xb858, /* popl %eax; movl $..., %eax */ 287 __NR_sigreturn, 288 0x80cd, /* int $0x80 */ 289 }; 290 291 static const struct { 292 u8 movl; 293 u32 val; 294 u16 int80; 295 u8 pad; 296 } __attribute__((packed)) rt_retcode = { 297 0xb8, /* movl $..., %eax */ 298 __NR_rt_sigreturn, 299 0x80cd, /* int $0x80 */ 300 0 301 }; 302 303 static int 304 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, 305 struct pt_regs *regs) 306 { 307 struct sigframe __user *frame; 308 void __user *restorer; 309 void __user *fp = NULL; 310 311 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 312 313 if (!user_access_begin(frame, sizeof(*frame))) 314 return -EFAULT; 315 316 unsafe_put_user(sig, &frame->sig, Efault); 317 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault); 318 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault); 319 if (current->mm->context.vdso) 320 restorer = current->mm->context.vdso + 321 vdso_image_32.sym___kernel_sigreturn; 322 else 323 restorer = &frame->retcode; 324 if (ksig->ka.sa.sa_flags & SA_RESTORER) 325 restorer = ksig->ka.sa.sa_restorer; 326 327 /* Set up to return from userspace. */ 328 unsafe_put_user(restorer, &frame->pretcode, Efault); 329 330 /* 331 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80 332 * 333 * WE DO NOT USE IT ANY MORE! It's only left here for historical 334 * reasons and because gdb uses it as a signature to notice 335 * signal handler stack frames. 336 */ 337 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault); 338 user_access_end(); 339 340 /* Set up registers for signal handler */ 341 regs->sp = (unsigned long)frame; 342 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 343 regs->ax = (unsigned long)sig; 344 regs->dx = 0; 345 regs->cx = 0; 346 347 regs->ds = __USER_DS; 348 regs->es = __USER_DS; 349 regs->ss = __USER_DS; 350 regs->cs = __USER_CS; 351 352 return 0; 353 354 Efault: 355 user_access_end(); 356 return -EFAULT; 357 } 358 359 static int __setup_rt_frame(int sig, struct ksignal *ksig, 360 sigset_t *set, struct pt_regs *regs) 361 { 362 struct rt_sigframe __user *frame; 363 void __user *restorer; 364 void __user *fp = NULL; 365 366 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 367 368 if (!user_access_begin(frame, sizeof(*frame))) 369 return -EFAULT; 370 371 unsafe_put_user(sig, &frame->sig, Efault); 372 unsafe_put_user(&frame->info, &frame->pinfo, Efault); 373 unsafe_put_user(&frame->uc, &frame->puc, Efault); 374 375 /* Create the ucontext. */ 376 if (static_cpu_has(X86_FEATURE_XSAVE)) 377 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault); 378 else 379 unsafe_put_user(0, &frame->uc.uc_flags, Efault); 380 unsafe_put_user(0, &frame->uc.uc_link, Efault); 381 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 382 383 /* Set up to return from userspace. */ 384 restorer = current->mm->context.vdso + 385 vdso_image_32.sym___kernel_rt_sigreturn; 386 if (ksig->ka.sa.sa_flags & SA_RESTORER) 387 restorer = ksig->ka.sa.sa_restorer; 388 unsafe_put_user(restorer, &frame->pretcode, Efault); 389 390 /* 391 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 392 * 393 * WE DO NOT USE IT ANY MORE! It's only left here for historical 394 * reasons and because gdb uses it as a signature to notice 395 * signal handler stack frames. 396 */ 397 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault); 398 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 399 unsafe_put_sigmask(set, frame, Efault); 400 user_access_end(); 401 402 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 403 return -EFAULT; 404 405 /* Set up registers for signal handler */ 406 regs->sp = (unsigned long)frame; 407 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 408 regs->ax = (unsigned long)sig; 409 regs->dx = (unsigned long)&frame->info; 410 regs->cx = (unsigned long)&frame->uc; 411 412 regs->ds = __USER_DS; 413 regs->es = __USER_DS; 414 regs->ss = __USER_DS; 415 regs->cs = __USER_CS; 416 417 return 0; 418 Efault: 419 user_access_end(); 420 return -EFAULT; 421 } 422 #else /* !CONFIG_X86_32 */ 423 static unsigned long frame_uc_flags(struct pt_regs *regs) 424 { 425 unsigned long flags; 426 427 if (boot_cpu_has(X86_FEATURE_XSAVE)) 428 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS; 429 else 430 flags = UC_SIGCONTEXT_SS; 431 432 if (likely(user_64bit_mode(regs))) 433 flags |= UC_STRICT_RESTORE_SS; 434 435 return flags; 436 } 437 438 static int __setup_rt_frame(int sig, struct ksignal *ksig, 439 sigset_t *set, struct pt_regs *regs) 440 { 441 struct rt_sigframe __user *frame; 442 void __user *fp = NULL; 443 unsigned long uc_flags; 444 445 /* x86-64 should always use SA_RESTORER. */ 446 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 447 return -EFAULT; 448 449 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); 450 uc_flags = frame_uc_flags(regs); 451 452 if (!user_access_begin(frame, sizeof(*frame))) 453 return -EFAULT; 454 455 /* Create the ucontext. */ 456 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 457 unsafe_put_user(0, &frame->uc.uc_link, Efault); 458 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 459 460 /* Set up to return from userspace. If provided, use a stub 461 already in userspace. */ 462 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault); 463 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 464 unsafe_put_sigmask(set, frame, Efault); 465 user_access_end(); 466 467 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 468 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 469 return -EFAULT; 470 } 471 472 /* Set up registers for signal handler */ 473 regs->di = sig; 474 /* In case the signal handler was declared without prototypes */ 475 regs->ax = 0; 476 477 /* This also works for non SA_SIGINFO handlers because they expect the 478 next argument after the signal number on the stack. */ 479 regs->si = (unsigned long)&frame->info; 480 regs->dx = (unsigned long)&frame->uc; 481 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 482 483 regs->sp = (unsigned long)frame; 484 485 /* 486 * Set up the CS and SS registers to run signal handlers in 487 * 64-bit mode, even if the handler happens to be interrupting 488 * 32-bit or 16-bit code. 489 * 490 * SS is subtle. In 64-bit mode, we don't need any particular 491 * SS descriptor, but we do need SS to be valid. It's possible 492 * that the old SS is entirely bogus -- this can happen if the 493 * signal we're trying to deliver is #GP or #SS caused by a bad 494 * SS value. We also have a compatbility issue here: DOSEMU 495 * relies on the contents of the SS register indicating the 496 * SS value at the time of the signal, even though that code in 497 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU 498 * avoids relying on sigreturn to restore SS; instead it uses 499 * a trampoline.) So we do our best: if the old SS was valid, 500 * we keep it. Otherwise we replace it. 501 */ 502 regs->cs = __USER_CS; 503 504 if (unlikely(regs->ss != __USER_DS)) 505 force_valid_ss(regs); 506 507 return 0; 508 509 Efault: 510 user_access_end(); 511 return -EFAULT; 512 } 513 #endif /* CONFIG_X86_32 */ 514 515 #ifdef CONFIG_X86_X32_ABI 516 static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to, 517 const struct kernel_siginfo *from) 518 { 519 struct compat_siginfo new; 520 521 copy_siginfo_to_external32(&new, from); 522 if (from->si_signo == SIGCHLD) { 523 new._sifields._sigchld_x32._utime = from->si_utime; 524 new._sifields._sigchld_x32._stime = from->si_stime; 525 } 526 if (copy_to_user(to, &new, sizeof(struct compat_siginfo))) 527 return -EFAULT; 528 return 0; 529 } 530 531 int copy_siginfo_to_user32(struct compat_siginfo __user *to, 532 const struct kernel_siginfo *from) 533 { 534 if (in_x32_syscall()) 535 return x32_copy_siginfo_to_user(to, from); 536 return __copy_siginfo_to_user32(to, from); 537 } 538 #endif /* CONFIG_X86_X32_ABI */ 539 540 static int x32_setup_rt_frame(struct ksignal *ksig, 541 compat_sigset_t *set, 542 struct pt_regs *regs) 543 { 544 #ifdef CONFIG_X86_X32_ABI 545 struct rt_sigframe_x32 __user *frame; 546 unsigned long uc_flags; 547 void __user *restorer; 548 void __user *fp = NULL; 549 550 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 551 return -EFAULT; 552 553 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 554 555 uc_flags = frame_uc_flags(regs); 556 557 if (!user_access_begin(frame, sizeof(*frame))) 558 return -EFAULT; 559 560 /* Create the ucontext. */ 561 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 562 unsafe_put_user(0, &frame->uc.uc_link, Efault); 563 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 564 unsafe_put_user(0, &frame->uc.uc__pad0, Efault); 565 restorer = ksig->ka.sa.sa_restorer; 566 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault); 567 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 568 unsafe_put_sigmask(set, frame, Efault); 569 user_access_end(); 570 571 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 572 if (x32_copy_siginfo_to_user(&frame->info, &ksig->info)) 573 return -EFAULT; 574 } 575 576 /* Set up registers for signal handler */ 577 regs->sp = (unsigned long) frame; 578 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 579 580 /* We use the x32 calling convention here... */ 581 regs->di = ksig->sig; 582 regs->si = (unsigned long) &frame->info; 583 regs->dx = (unsigned long) &frame->uc; 584 585 loadsegment(ds, __USER_DS); 586 loadsegment(es, __USER_DS); 587 588 regs->cs = __USER_CS; 589 regs->ss = __USER_DS; 590 #endif /* CONFIG_X86_X32_ABI */ 591 592 return 0; 593 #ifdef CONFIG_X86_X32_ABI 594 Efault: 595 user_access_end(); 596 return -EFAULT; 597 #endif 598 } 599 600 /* 601 * Do a signal return; undo the signal stack. 602 */ 603 #ifdef CONFIG_X86_32 604 SYSCALL_DEFINE0(sigreturn) 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(frame, sizeof(*frame))) 613 goto badframe; 614 if (__get_user(set.sig[0], &frame->sc.oldmask) || 615 __get_user(set.sig[1], &frame->extramask[0])) 616 goto badframe; 617 618 set_current_blocked(&set); 619 620 /* 621 * x86_32 has no uc_flags bits relevant to restore_sigcontext. 622 * Save a few cycles by skipping the __get_user. 623 */ 624 if (restore_sigcontext(regs, &frame->sc, 0)) 625 goto badframe; 626 return regs->ax; 627 628 badframe: 629 signal_fault(regs, frame, "sigreturn"); 630 631 return 0; 632 } 633 #endif /* CONFIG_X86_32 */ 634 635 SYSCALL_DEFINE0(rt_sigreturn) 636 { 637 struct pt_regs *regs = current_pt_regs(); 638 struct rt_sigframe __user *frame; 639 sigset_t set; 640 unsigned long uc_flags; 641 642 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 643 if (!access_ok(frame, sizeof(*frame))) 644 goto badframe; 645 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask)) 646 goto badframe; 647 if (__get_user(uc_flags, &frame->uc.uc_flags)) 648 goto badframe; 649 650 set_current_blocked(&set); 651 652 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 653 goto badframe; 654 655 if (restore_altstack(&frame->uc.uc_stack)) 656 goto badframe; 657 658 return regs->ax; 659 660 badframe: 661 signal_fault(regs, frame, "rt_sigreturn"); 662 return 0; 663 } 664 665 static inline int is_ia32_compat_frame(struct ksignal *ksig) 666 { 667 return IS_ENABLED(CONFIG_IA32_EMULATION) && 668 ksig->ka.sa.sa_flags & SA_IA32_ABI; 669 } 670 671 static inline int is_ia32_frame(struct ksignal *ksig) 672 { 673 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); 674 } 675 676 static inline int is_x32_frame(struct ksignal *ksig) 677 { 678 return IS_ENABLED(CONFIG_X86_X32_ABI) && 679 ksig->ka.sa.sa_flags & SA_X32_ABI; 680 } 681 682 static int 683 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 684 { 685 int usig = ksig->sig; 686 sigset_t *set = sigmask_to_save(); 687 compat_sigset_t *cset = (compat_sigset_t *) set; 688 689 /* Perform fixup for the pre-signal frame. */ 690 rseq_signal_deliver(ksig, regs); 691 692 /* Set up the stack frame */ 693 if (is_ia32_frame(ksig)) { 694 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 695 return ia32_setup_rt_frame(usig, ksig, cset, regs); 696 else 697 return ia32_setup_frame(usig, ksig, cset, regs); 698 } else if (is_x32_frame(ksig)) { 699 return x32_setup_rt_frame(ksig, cset, regs); 700 } else { 701 return __setup_rt_frame(ksig->sig, ksig, set, regs); 702 } 703 } 704 705 static void 706 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 707 { 708 bool stepping, failed; 709 struct fpu *fpu = ¤t->thread.fpu; 710 711 if (v8086_mode(regs)) 712 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); 713 714 /* Are we from a system call? */ 715 if (syscall_get_nr(current, regs) >= 0) { 716 /* If so, check system call restarting.. */ 717 switch (syscall_get_error(current, regs)) { 718 case -ERESTART_RESTARTBLOCK: 719 case -ERESTARTNOHAND: 720 regs->ax = -EINTR; 721 break; 722 723 case -ERESTARTSYS: 724 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 725 regs->ax = -EINTR; 726 break; 727 } 728 /* fallthrough */ 729 case -ERESTARTNOINTR: 730 regs->ax = regs->orig_ax; 731 regs->ip -= 2; 732 break; 733 } 734 } 735 736 /* 737 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now 738 * so that register information in the sigcontext is correct and 739 * then notify the tracer before entering the signal handler. 740 */ 741 stepping = test_thread_flag(TIF_SINGLESTEP); 742 if (stepping) 743 user_disable_single_step(current); 744 745 failed = (setup_rt_frame(ksig, regs) < 0); 746 if (!failed) { 747 /* 748 * Clear the direction flag as per the ABI for function entry. 749 * 750 * Clear RF when entering the signal handler, because 751 * it might disable possible debug exception from the 752 * signal handler. 753 * 754 * Clear TF for the case when it wasn't set by debugger to 755 * avoid the recursive send_sigtrap() in SIGTRAP handler. 756 */ 757 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); 758 /* 759 * Ensure the signal handler starts with the new fpu state. 760 */ 761 fpu__clear_user_states(fpu); 762 } 763 signal_setup_done(failed, ksig, stepping); 764 } 765 766 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) 767 { 768 /* 769 * This function is fundamentally broken as currently 770 * implemented. 771 * 772 * The idea is that we want to trigger a call to the 773 * restart_block() syscall and that we want in_ia32_syscall(), 774 * in_x32_syscall(), etc. to match whatever they were in the 775 * syscall being restarted. We assume that the syscall 776 * instruction at (regs->ip - 2) matches whatever syscall 777 * instruction we used to enter in the first place. 778 * 779 * The problem is that we can get here when ptrace pokes 780 * syscall-like values into regs even if we're not in a syscall 781 * at all. 782 * 783 * For now, we maintain historical behavior and guess based on 784 * stored state. We could do better by saving the actual 785 * syscall arch in restart_block or (with caveats on x32) by 786 * checking if regs->ip points to 'int $0x80'. The current 787 * behavior is incorrect if a tracer has a different bitness 788 * than the tracee. 789 */ 790 #ifdef CONFIG_IA32_EMULATION 791 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED)) 792 return __NR_ia32_restart_syscall; 793 #endif 794 #ifdef CONFIG_X86_X32_ABI 795 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); 796 #else 797 return __NR_restart_syscall; 798 #endif 799 } 800 801 /* 802 * Note that 'init' is a special process: it doesn't get signals it doesn't 803 * want to handle. Thus you cannot kill init even with a SIGKILL even by 804 * mistake. 805 */ 806 void do_signal(struct pt_regs *regs) 807 { 808 struct ksignal ksig; 809 810 if (get_signal(&ksig)) { 811 /* Whee! Actually deliver the signal. */ 812 handle_signal(&ksig, regs); 813 return; 814 } 815 816 /* Did we come from a system call? */ 817 if (syscall_get_nr(current, regs) >= 0) { 818 /* Restart the system call - no handlers present */ 819 switch (syscall_get_error(current, regs)) { 820 case -ERESTARTNOHAND: 821 case -ERESTARTSYS: 822 case -ERESTARTNOINTR: 823 regs->ax = regs->orig_ax; 824 regs->ip -= 2; 825 break; 826 827 case -ERESTART_RESTARTBLOCK: 828 regs->ax = get_nr_restart_syscall(regs); 829 regs->ip -= 2; 830 break; 831 } 832 } 833 834 /* 835 * If there's no signal to deliver, we just put the saved sigmask 836 * back. 837 */ 838 restore_saved_sigmask(); 839 } 840 841 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 842 { 843 struct task_struct *me = current; 844 845 if (show_unhandled_signals && printk_ratelimit()) { 846 printk("%s" 847 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 848 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, 849 me->comm, me->pid, where, frame, 850 regs->ip, regs->sp, regs->orig_ax); 851 print_vma_addr(KERN_CONT " in ", regs->ip); 852 pr_cont("\n"); 853 } 854 855 force_sig(SIGSEGV); 856 } 857 858 #ifdef CONFIG_X86_X32_ABI 859 COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn) 860 { 861 struct pt_regs *regs = current_pt_regs(); 862 struct rt_sigframe_x32 __user *frame; 863 sigset_t set; 864 unsigned long uc_flags; 865 866 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); 867 868 if (!access_ok(frame, sizeof(*frame))) 869 goto badframe; 870 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask)) 871 goto badframe; 872 if (__get_user(uc_flags, &frame->uc.uc_flags)) 873 goto badframe; 874 875 set_current_blocked(&set); 876 877 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 878 goto badframe; 879 880 if (compat_restore_altstack(&frame->uc.uc_stack)) 881 goto badframe; 882 883 return regs->ax; 884 885 badframe: 886 signal_fault(regs, frame, "x32 rt_sigreturn"); 887 return 0; 888 } 889 #endif 890