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 /* x86 ABI requires 16-byte alignment */ 216 #define FRAME_ALIGNMENT 16UL 217 218 #define MAX_FRAME_PADDING (FRAME_ALIGNMENT - 1) 219 220 /* 221 * Determine which stack to use.. 222 */ 223 static unsigned long align_sigframe(unsigned long sp) 224 { 225 #ifdef CONFIG_X86_32 226 /* 227 * Align the stack pointer according to the i386 ABI, 228 * i.e. so that on function entry ((sp + 4) & 15) == 0. 229 */ 230 sp = ((sp + 4) & -FRAME_ALIGNMENT) - 4; 231 #else /* !CONFIG_X86_32 */ 232 sp = round_down(sp, FRAME_ALIGNMENT) - 8; 233 #endif 234 return sp; 235 } 236 237 static void __user * 238 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, 239 void __user **fpstate) 240 { 241 /* Default to using normal stack */ 242 bool nested_altstack = on_sig_stack(regs->sp); 243 bool entering_altstack = false; 244 unsigned long math_size = 0; 245 unsigned long sp = regs->sp; 246 unsigned long buf_fx = 0; 247 int ret; 248 249 /* redzone */ 250 if (IS_ENABLED(CONFIG_X86_64)) 251 sp -= 128; 252 253 /* This is the X/Open sanctioned signal stack switching. */ 254 if (ka->sa.sa_flags & SA_ONSTACK) { 255 /* 256 * This checks nested_altstack via sas_ss_flags(). Sensible 257 * programs use SS_AUTODISARM, which disables that check, and 258 * programs that don't use SS_AUTODISARM get compatible. 259 */ 260 if (sas_ss_flags(sp) == 0) { 261 sp = current->sas_ss_sp + current->sas_ss_size; 262 entering_altstack = true; 263 } 264 } else if (IS_ENABLED(CONFIG_X86_32) && 265 !nested_altstack && 266 regs->ss != __USER_DS && 267 !(ka->sa.sa_flags & SA_RESTORER) && 268 ka->sa.sa_restorer) { 269 /* This is the legacy signal stack switching. */ 270 sp = (unsigned long) ka->sa.sa_restorer; 271 entering_altstack = true; 272 } 273 274 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32), 275 &buf_fx, &math_size); 276 *fpstate = (void __user *)sp; 277 278 sp = align_sigframe(sp - frame_size); 279 280 /* 281 * If we are on the alternate signal stack and would overflow it, don't. 282 * Return an always-bogus address instead so we will die with SIGSEGV. 283 */ 284 if (unlikely((nested_altstack || entering_altstack) && 285 !__on_sig_stack(sp))) { 286 287 if (show_unhandled_signals && printk_ratelimit()) 288 pr_info("%s[%d] overflowed sigaltstack\n", 289 current->comm, task_pid_nr(current)); 290 291 return (void __user *)-1L; 292 } 293 294 /* save i387 and extended state */ 295 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size); 296 if (ret < 0) 297 return (void __user *)-1L; 298 299 return (void __user *)sp; 300 } 301 302 #ifdef CONFIG_X86_32 303 static const struct { 304 u16 poplmovl; 305 u32 val; 306 u16 int80; 307 } __attribute__((packed)) retcode = { 308 0xb858, /* popl %eax; movl $..., %eax */ 309 __NR_sigreturn, 310 0x80cd, /* int $0x80 */ 311 }; 312 313 static const struct { 314 u8 movl; 315 u32 val; 316 u16 int80; 317 u8 pad; 318 } __attribute__((packed)) rt_retcode = { 319 0xb8, /* movl $..., %eax */ 320 __NR_rt_sigreturn, 321 0x80cd, /* int $0x80 */ 322 0 323 }; 324 325 static int 326 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, 327 struct pt_regs *regs) 328 { 329 struct sigframe __user *frame; 330 void __user *restorer; 331 void __user *fp = NULL; 332 333 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 334 335 if (!user_access_begin(frame, sizeof(*frame))) 336 return -EFAULT; 337 338 unsafe_put_user(sig, &frame->sig, Efault); 339 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault); 340 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault); 341 if (current->mm->context.vdso) 342 restorer = current->mm->context.vdso + 343 vdso_image_32.sym___kernel_sigreturn; 344 else 345 restorer = &frame->retcode; 346 if (ksig->ka.sa.sa_flags & SA_RESTORER) 347 restorer = ksig->ka.sa.sa_restorer; 348 349 /* Set up to return from userspace. */ 350 unsafe_put_user(restorer, &frame->pretcode, Efault); 351 352 /* 353 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80 354 * 355 * WE DO NOT USE IT ANY MORE! It's only left here for historical 356 * reasons and because gdb uses it as a signature to notice 357 * signal handler stack frames. 358 */ 359 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault); 360 user_access_end(); 361 362 /* Set up registers for signal handler */ 363 regs->sp = (unsigned long)frame; 364 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 365 regs->ax = (unsigned long)sig; 366 regs->dx = 0; 367 regs->cx = 0; 368 369 regs->ds = __USER_DS; 370 regs->es = __USER_DS; 371 regs->ss = __USER_DS; 372 regs->cs = __USER_CS; 373 374 return 0; 375 376 Efault: 377 user_access_end(); 378 return -EFAULT; 379 } 380 381 static int __setup_rt_frame(int sig, struct ksignal *ksig, 382 sigset_t *set, struct pt_regs *regs) 383 { 384 struct rt_sigframe __user *frame; 385 void __user *restorer; 386 void __user *fp = NULL; 387 388 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 389 390 if (!user_access_begin(frame, sizeof(*frame))) 391 return -EFAULT; 392 393 unsafe_put_user(sig, &frame->sig, Efault); 394 unsafe_put_user(&frame->info, &frame->pinfo, Efault); 395 unsafe_put_user(&frame->uc, &frame->puc, Efault); 396 397 /* Create the ucontext. */ 398 if (static_cpu_has(X86_FEATURE_XSAVE)) 399 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault); 400 else 401 unsafe_put_user(0, &frame->uc.uc_flags, Efault); 402 unsafe_put_user(0, &frame->uc.uc_link, Efault); 403 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 404 405 /* Set up to return from userspace. */ 406 restorer = current->mm->context.vdso + 407 vdso_image_32.sym___kernel_rt_sigreturn; 408 if (ksig->ka.sa.sa_flags & SA_RESTORER) 409 restorer = ksig->ka.sa.sa_restorer; 410 unsafe_put_user(restorer, &frame->pretcode, Efault); 411 412 /* 413 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 414 * 415 * WE DO NOT USE IT ANY MORE! It's only left here for historical 416 * reasons and because gdb uses it as a signature to notice 417 * signal handler stack frames. 418 */ 419 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault); 420 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 421 unsafe_put_sigmask(set, frame, Efault); 422 user_access_end(); 423 424 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 425 return -EFAULT; 426 427 /* Set up registers for signal handler */ 428 regs->sp = (unsigned long)frame; 429 regs->ip = (unsigned long)ksig->ka.sa.sa_handler; 430 regs->ax = (unsigned long)sig; 431 regs->dx = (unsigned long)&frame->info; 432 regs->cx = (unsigned long)&frame->uc; 433 434 regs->ds = __USER_DS; 435 regs->es = __USER_DS; 436 regs->ss = __USER_DS; 437 regs->cs = __USER_CS; 438 439 return 0; 440 Efault: 441 user_access_end(); 442 return -EFAULT; 443 } 444 #else /* !CONFIG_X86_32 */ 445 static unsigned long frame_uc_flags(struct pt_regs *regs) 446 { 447 unsigned long flags; 448 449 if (boot_cpu_has(X86_FEATURE_XSAVE)) 450 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS; 451 else 452 flags = UC_SIGCONTEXT_SS; 453 454 if (likely(user_64bit_mode(regs))) 455 flags |= UC_STRICT_RESTORE_SS; 456 457 return flags; 458 } 459 460 static int __setup_rt_frame(int sig, struct ksignal *ksig, 461 sigset_t *set, struct pt_regs *regs) 462 { 463 struct rt_sigframe __user *frame; 464 void __user *fp = NULL; 465 unsigned long uc_flags; 466 467 /* x86-64 should always use SA_RESTORER. */ 468 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 469 return -EFAULT; 470 471 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); 472 uc_flags = frame_uc_flags(regs); 473 474 if (!user_access_begin(frame, sizeof(*frame))) 475 return -EFAULT; 476 477 /* Create the ucontext. */ 478 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 479 unsafe_put_user(0, &frame->uc.uc_link, Efault); 480 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 481 482 /* Set up to return from userspace. If provided, use a stub 483 already in userspace. */ 484 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault); 485 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 486 unsafe_put_sigmask(set, frame, Efault); 487 user_access_end(); 488 489 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 490 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 491 return -EFAULT; 492 } 493 494 /* Set up registers for signal handler */ 495 regs->di = sig; 496 /* In case the signal handler was declared without prototypes */ 497 regs->ax = 0; 498 499 /* This also works for non SA_SIGINFO handlers because they expect the 500 next argument after the signal number on the stack. */ 501 regs->si = (unsigned long)&frame->info; 502 regs->dx = (unsigned long)&frame->uc; 503 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 504 505 regs->sp = (unsigned long)frame; 506 507 /* 508 * Set up the CS and SS registers to run signal handlers in 509 * 64-bit mode, even if the handler happens to be interrupting 510 * 32-bit or 16-bit code. 511 * 512 * SS is subtle. In 64-bit mode, we don't need any particular 513 * SS descriptor, but we do need SS to be valid. It's possible 514 * that the old SS is entirely bogus -- this can happen if the 515 * signal we're trying to deliver is #GP or #SS caused by a bad 516 * SS value. We also have a compatibility issue here: DOSEMU 517 * relies on the contents of the SS register indicating the 518 * SS value at the time of the signal, even though that code in 519 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU 520 * avoids relying on sigreturn to restore SS; instead it uses 521 * a trampoline.) So we do our best: if the old SS was valid, 522 * we keep it. Otherwise we replace it. 523 */ 524 regs->cs = __USER_CS; 525 526 if (unlikely(regs->ss != __USER_DS)) 527 force_valid_ss(regs); 528 529 return 0; 530 531 Efault: 532 user_access_end(); 533 return -EFAULT; 534 } 535 #endif /* CONFIG_X86_32 */ 536 537 #ifdef CONFIG_X86_X32_ABI 538 static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to, 539 const struct kernel_siginfo *from) 540 { 541 struct compat_siginfo new; 542 543 copy_siginfo_to_external32(&new, from); 544 if (from->si_signo == SIGCHLD) { 545 new._sifields._sigchld_x32._utime = from->si_utime; 546 new._sifields._sigchld_x32._stime = from->si_stime; 547 } 548 if (copy_to_user(to, &new, sizeof(struct compat_siginfo))) 549 return -EFAULT; 550 return 0; 551 } 552 553 int copy_siginfo_to_user32(struct compat_siginfo __user *to, 554 const struct kernel_siginfo *from) 555 { 556 if (in_x32_syscall()) 557 return x32_copy_siginfo_to_user(to, from); 558 return __copy_siginfo_to_user32(to, from); 559 } 560 #endif /* CONFIG_X86_X32_ABI */ 561 562 static int x32_setup_rt_frame(struct ksignal *ksig, 563 compat_sigset_t *set, 564 struct pt_regs *regs) 565 { 566 #ifdef CONFIG_X86_X32_ABI 567 struct rt_sigframe_x32 __user *frame; 568 unsigned long uc_flags; 569 void __user *restorer; 570 void __user *fp = NULL; 571 572 if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) 573 return -EFAULT; 574 575 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); 576 577 uc_flags = frame_uc_flags(regs); 578 579 if (!user_access_begin(frame, sizeof(*frame))) 580 return -EFAULT; 581 582 /* Create the ucontext. */ 583 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); 584 unsafe_put_user(0, &frame->uc.uc_link, Efault); 585 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); 586 unsafe_put_user(0, &frame->uc.uc__pad0, Efault); 587 restorer = ksig->ka.sa.sa_restorer; 588 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault); 589 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); 590 unsafe_put_sigmask(set, frame, Efault); 591 user_access_end(); 592 593 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 594 if (x32_copy_siginfo_to_user(&frame->info, &ksig->info)) 595 return -EFAULT; 596 } 597 598 /* Set up registers for signal handler */ 599 regs->sp = (unsigned long) frame; 600 regs->ip = (unsigned long) ksig->ka.sa.sa_handler; 601 602 /* We use the x32 calling convention here... */ 603 regs->di = ksig->sig; 604 regs->si = (unsigned long) &frame->info; 605 regs->dx = (unsigned long) &frame->uc; 606 607 loadsegment(ds, __USER_DS); 608 loadsegment(es, __USER_DS); 609 610 regs->cs = __USER_CS; 611 regs->ss = __USER_DS; 612 #endif /* CONFIG_X86_X32_ABI */ 613 614 return 0; 615 #ifdef CONFIG_X86_X32_ABI 616 Efault: 617 user_access_end(); 618 return -EFAULT; 619 #endif 620 } 621 622 /* 623 * Do a signal return; undo the signal stack. 624 */ 625 #ifdef CONFIG_X86_32 626 SYSCALL_DEFINE0(sigreturn) 627 { 628 struct pt_regs *regs = current_pt_regs(); 629 struct sigframe __user *frame; 630 sigset_t set; 631 632 frame = (struct sigframe __user *)(regs->sp - 8); 633 634 if (!access_ok(frame, sizeof(*frame))) 635 goto badframe; 636 if (__get_user(set.sig[0], &frame->sc.oldmask) || 637 __get_user(set.sig[1], &frame->extramask[0])) 638 goto badframe; 639 640 set_current_blocked(&set); 641 642 /* 643 * x86_32 has no uc_flags bits relevant to restore_sigcontext. 644 * Save a few cycles by skipping the __get_user. 645 */ 646 if (restore_sigcontext(regs, &frame->sc, 0)) 647 goto badframe; 648 return regs->ax; 649 650 badframe: 651 signal_fault(regs, frame, "sigreturn"); 652 653 return 0; 654 } 655 #endif /* CONFIG_X86_32 */ 656 657 SYSCALL_DEFINE0(rt_sigreturn) 658 { 659 struct pt_regs *regs = current_pt_regs(); 660 struct rt_sigframe __user *frame; 661 sigset_t set; 662 unsigned long uc_flags; 663 664 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 665 if (!access_ok(frame, sizeof(*frame))) 666 goto badframe; 667 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask)) 668 goto badframe; 669 if (__get_user(uc_flags, &frame->uc.uc_flags)) 670 goto badframe; 671 672 set_current_blocked(&set); 673 674 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 675 goto badframe; 676 677 if (restore_altstack(&frame->uc.uc_stack)) 678 goto badframe; 679 680 return regs->ax; 681 682 badframe: 683 signal_fault(regs, frame, "rt_sigreturn"); 684 return 0; 685 } 686 687 /* 688 * There are four different struct types for signal frame: sigframe_ia32, 689 * rt_sigframe_ia32, rt_sigframe_x32, and rt_sigframe. Use the worst case 690 * -- the largest size. It means the size for 64-bit apps is a bit more 691 * than needed, but this keeps the code simple. 692 */ 693 #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) 694 # define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct sigframe_ia32) 695 #else 696 # define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct rt_sigframe) 697 #endif 698 699 /* 700 * The FP state frame contains an XSAVE buffer which must be 64-byte aligned. 701 * If a signal frame starts at an unaligned address, extra space is required. 702 * This is the max alignment padding, conservatively. 703 */ 704 #define MAX_XSAVE_PADDING 63UL 705 706 /* 707 * The frame data is composed of the following areas and laid out as: 708 * 709 * ------------------------- 710 * | alignment padding | 711 * ------------------------- 712 * | (f)xsave frame | 713 * ------------------------- 714 * | fsave header | 715 * ------------------------- 716 * | alignment padding | 717 * ------------------------- 718 * | siginfo + ucontext | 719 * ------------------------- 720 */ 721 722 /* max_frame_size tells userspace the worst case signal stack size. */ 723 static unsigned long __ro_after_init max_frame_size; 724 725 void __init init_sigframe_size(void) 726 { 727 max_frame_size = MAX_FRAME_SIGINFO_UCTXT_SIZE + MAX_FRAME_PADDING; 728 729 max_frame_size += fpu__get_fpstate_size() + MAX_XSAVE_PADDING; 730 731 /* Userspace expects an aligned size. */ 732 max_frame_size = round_up(max_frame_size, FRAME_ALIGNMENT); 733 734 pr_info("max sigframe size: %lu\n", max_frame_size); 735 } 736 737 unsigned long get_sigframe_size(void) 738 { 739 return max_frame_size; 740 } 741 742 static inline int is_ia32_compat_frame(struct ksignal *ksig) 743 { 744 return IS_ENABLED(CONFIG_IA32_EMULATION) && 745 ksig->ka.sa.sa_flags & SA_IA32_ABI; 746 } 747 748 static inline int is_ia32_frame(struct ksignal *ksig) 749 { 750 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); 751 } 752 753 static inline int is_x32_frame(struct ksignal *ksig) 754 { 755 return IS_ENABLED(CONFIG_X86_X32_ABI) && 756 ksig->ka.sa.sa_flags & SA_X32_ABI; 757 } 758 759 static int 760 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 761 { 762 int usig = ksig->sig; 763 sigset_t *set = sigmask_to_save(); 764 compat_sigset_t *cset = (compat_sigset_t *) set; 765 766 /* Perform fixup for the pre-signal frame. */ 767 rseq_signal_deliver(ksig, regs); 768 769 /* Set up the stack frame */ 770 if (is_ia32_frame(ksig)) { 771 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 772 return ia32_setup_rt_frame(usig, ksig, cset, regs); 773 else 774 return ia32_setup_frame(usig, ksig, cset, regs); 775 } else if (is_x32_frame(ksig)) { 776 return x32_setup_rt_frame(ksig, cset, regs); 777 } else { 778 return __setup_rt_frame(ksig->sig, ksig, set, regs); 779 } 780 } 781 782 static void 783 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 784 { 785 bool stepping, failed; 786 struct fpu *fpu = ¤t->thread.fpu; 787 788 if (v8086_mode(regs)) 789 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); 790 791 /* Are we from a system call? */ 792 if (syscall_get_nr(current, regs) != -1) { 793 /* If so, check system call restarting.. */ 794 switch (syscall_get_error(current, regs)) { 795 case -ERESTART_RESTARTBLOCK: 796 case -ERESTARTNOHAND: 797 regs->ax = -EINTR; 798 break; 799 800 case -ERESTARTSYS: 801 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 802 regs->ax = -EINTR; 803 break; 804 } 805 fallthrough; 806 case -ERESTARTNOINTR: 807 regs->ax = regs->orig_ax; 808 regs->ip -= 2; 809 break; 810 } 811 } 812 813 /* 814 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now 815 * so that register information in the sigcontext is correct and 816 * then notify the tracer before entering the signal handler. 817 */ 818 stepping = test_thread_flag(TIF_SINGLESTEP); 819 if (stepping) 820 user_disable_single_step(current); 821 822 failed = (setup_rt_frame(ksig, regs) < 0); 823 if (!failed) { 824 /* 825 * Clear the direction flag as per the ABI for function entry. 826 * 827 * Clear RF when entering the signal handler, because 828 * it might disable possible debug exception from the 829 * signal handler. 830 * 831 * Clear TF for the case when it wasn't set by debugger to 832 * avoid the recursive send_sigtrap() in SIGTRAP handler. 833 */ 834 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); 835 /* 836 * Ensure the signal handler starts with the new fpu state. 837 */ 838 fpu__clear_user_states(fpu); 839 } 840 signal_setup_done(failed, ksig, stepping); 841 } 842 843 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) 844 { 845 #ifdef CONFIG_IA32_EMULATION 846 if (current->restart_block.arch_data & TS_COMPAT) 847 return __NR_ia32_restart_syscall; 848 #endif 849 #ifdef CONFIG_X86_X32_ABI 850 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); 851 #else 852 return __NR_restart_syscall; 853 #endif 854 } 855 856 /* 857 * Note that 'init' is a special process: it doesn't get signals it doesn't 858 * want to handle. Thus you cannot kill init even with a SIGKILL even by 859 * mistake. 860 */ 861 void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal) 862 { 863 struct ksignal ksig; 864 865 if (has_signal && get_signal(&ksig)) { 866 /* Whee! Actually deliver the signal. */ 867 handle_signal(&ksig, regs); 868 return; 869 } 870 871 /* Did we come from a system call? */ 872 if (syscall_get_nr(current, regs) != -1) { 873 /* Restart the system call - no handlers present */ 874 switch (syscall_get_error(current, regs)) { 875 case -ERESTARTNOHAND: 876 case -ERESTARTSYS: 877 case -ERESTARTNOINTR: 878 regs->ax = regs->orig_ax; 879 regs->ip -= 2; 880 break; 881 882 case -ERESTART_RESTARTBLOCK: 883 regs->ax = get_nr_restart_syscall(regs); 884 regs->ip -= 2; 885 break; 886 } 887 } 888 889 /* 890 * If there's no signal to deliver, we just put the saved sigmask 891 * back. 892 */ 893 restore_saved_sigmask(); 894 } 895 896 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 897 { 898 struct task_struct *me = current; 899 900 if (show_unhandled_signals && printk_ratelimit()) { 901 printk("%s" 902 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 903 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, 904 me->comm, me->pid, where, frame, 905 regs->ip, regs->sp, regs->orig_ax); 906 print_vma_addr(KERN_CONT " in ", regs->ip); 907 pr_cont("\n"); 908 } 909 910 force_sig(SIGSEGV); 911 } 912 913 #ifdef CONFIG_X86_X32_ABI 914 COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn) 915 { 916 struct pt_regs *regs = current_pt_regs(); 917 struct rt_sigframe_x32 __user *frame; 918 sigset_t set; 919 unsigned long uc_flags; 920 921 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); 922 923 if (!access_ok(frame, sizeof(*frame))) 924 goto badframe; 925 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask)) 926 goto badframe; 927 if (__get_user(uc_flags, &frame->uc.uc_flags)) 928 goto badframe; 929 930 set_current_blocked(&set); 931 932 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) 933 goto badframe; 934 935 if (compat_restore_altstack(&frame->uc.uc_stack)) 936 goto badframe; 937 938 return regs->ax; 939 940 badframe: 941 signal_fault(regs, frame, "x32 rt_sigreturn"); 942 return 0; 943 } 944 #endif 945