arch/x86/kernel/signal_32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Copyright (C) 1991, 1992  Linus Torvalds
   4  *
   5  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   6  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   7  *  2000-12-*   x86-64 compatibility mode signal handling by Andi Kleen
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/sched/task_stack.h>
  12 #include <linux/mm.h>
  13 #include <linux/smp.h>
  14 #include <linux/kernel.h>
  15 #include <linux/errno.h>
  16 #include <linux/wait.h>
  17 #include <linux/unistd.h>
  18 #include <linux/stddef.h>
  19 #include <linux/personality.h>
  20 #include <linux/compat.h>
  21 #include <linux/binfmts.h>
  22 #include <linux/syscalls.h>
  23 #include <asm/ucontext.h>
  24 #include <linux/uaccess.h>
  25 #include <asm/fpu/signal.h>
  26 #include <asm/ptrace.h>
  27 #include <asm/user32.h>
  28 #include <uapi/asm/sigcontext.h>
  29 #include <asm/proto.h>
  30 #include <asm/vdso.h>
  31 #include <asm/sigframe.h>
  32 #include <asm/sighandling.h>
  33 #include <asm/smap.h>
  34 #include <asm/gsseg.h>
  35
  36 #ifdef CONFIG_IA32_EMULATION
  37 #include <asm/unistd_32_ia32.h>
  38
  39 static inline void reload_segments(struct sigcontext_32 *sc)
  40 {
  41         unsigned int cur;
  42
  43         savesegment(gs, cur);
  44         if ((sc->gs | 0x03) != cur)
  45                 load_gs_index(sc->gs | 0x03);
  46         savesegment(fs, cur);
  47         if ((sc->fs | 0x03) != cur)
  48                 loadsegment(fs, sc->fs | 0x03);
  49         savesegment(ds, cur);
  50         if ((sc->ds | 0x03) != cur)
  51                 loadsegment(ds, sc->ds | 0x03);
  52         savesegment(es, cur);
  53         if ((sc->es | 0x03) != cur)
  54                 loadsegment(es, sc->es | 0x03);
  55 }
  56
  57 #define sigset32_t                      compat_sigset_t
  58 #define siginfo32_t                     compat_siginfo_t
  59 #define restore_altstack32              compat_restore_altstack
  60 #define unsafe_save_altstack32          unsafe_compat_save_altstack
  61
  62 #else
  63
  64 #define sigset32_t                      sigset_t
  65 #define siginfo32_t                     siginfo_t
  66 #define __NR_ia32_sigreturn             __NR_sigreturn
  67 #define __NR_ia32_rt_sigreturn          __NR_rt_sigreturn
  68 #define restore_altstack32              restore_altstack
  69 #define unsafe_save_altstack32          unsafe_save_altstack
  70 #define __copy_siginfo_to_user32        copy_siginfo_to_user
  71
  72 #endif
  73
  74 /*
  75  * Do a signal return; undo the signal stack.
  76  */
  77 static bool ia32_restore_sigcontext(struct pt_regs *regs,
  78                                     struct sigcontext_32 __user *usc)
  79 {
  80         struct sigcontext_32 sc;
  81
  82         /* Always make any pending restarted system calls return -EINTR */
  83         current->restart_block.fn = do_no_restart_syscall;
  84
  85         if (unlikely(copy_from_user(&sc, usc, sizeof(sc))))
  86                 return false;
  87
  88         /* Get only the ia32 registers. */
  89         regs->bx = sc.bx;
  90         regs->cx = sc.cx;
  91         regs->dx = sc.dx;
  92         regs->si = sc.si;
  93         regs->di = sc.di;
  94         regs->bp = sc.bp;
  95         regs->ax = sc.ax;
  96         regs->sp = sc.sp;
  97         regs->ip = sc.ip;
  98
  99         /* Get CS/SS and force CPL3 */
 100         regs->cs = sc.cs | 0x03;
 101         regs->ss = sc.ss | 0x03;
 102
 103         regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
 104         /* disable syscall checks */
 105         regs->orig_ax = -1;
 106
 107 #ifdef CONFIG_IA32_EMULATION
 108         /*
 109          * Reload fs and gs if they have changed in the signal
 110          * handler.  This does not handle long fs/gs base changes in
 111          * the handler, but does not clobber them at least in the
 112          * normal case.
 113          */
 114         reload_segments(&sc);
 115 #else
 116         loadsegment(gs, sc.gs);
 117         regs->fs = sc.fs;
 118         regs->es = sc.es;
 119         regs->ds = sc.ds;
 120 #endif
 121
 122         return fpu__restore_sig(compat_ptr(sc.fpstate), 1);
 123 }
 124
 125 SYSCALL32_DEFINE0(sigreturn)
 126 {
 127         struct pt_regs *regs = current_pt_regs();
 128         struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
 129         sigset_t set;
 130
 131         if (!access_ok(frame, sizeof(*frame)))
 132                 goto badframe;
 133         if (__get_user(set.sig[0], &frame->sc.oldmask)
 134             || __get_user(((__u32 *)&set)[1], &frame->extramask[0]))
 135                 goto badframe;
 136
 137         set_current_blocked(&set);
 138
 139         if (!ia32_restore_sigcontext(regs, &frame->sc))
 140                 goto badframe;
 141         return regs->ax;
 142
 143 badframe:
 144         signal_fault(regs, frame, "32bit sigreturn");
 145         return 0;
 146 }
 147
 148 SYSCALL32_DEFINE0(rt_sigreturn)
 149 {
 150         struct pt_regs *regs = current_pt_regs();
 151         struct rt_sigframe_ia32 __user *frame;
 152         sigset_t set;
 153
 154         frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
 155
 156         if (!access_ok(frame, sizeof(*frame)))
 157                 goto badframe;
 158         if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
 159                 goto badframe;
 160
 161         set_current_blocked(&set);
 162
 163         if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
 164                 goto badframe;
 165
 166         if (restore_altstack32(&frame->uc.uc_stack))
 167                 goto badframe;
 168
 169         return regs->ax;
 170
 171 badframe:
 172         signal_fault(regs, frame, "32bit rt sigreturn");
 173         return 0;
 174 }
 175
 176 /*
 177  * Set up a signal frame.
 178  */
 179
 180 #define get_user_seg(seg)       ({ unsigned int v; savesegment(seg, v); v; })
 181
 182 static __always_inline int
 183 __unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc,
 184                             void __user *fpstate,
 185                             struct pt_regs *regs, unsigned int mask)
 186 {
 187         unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
 188 #ifdef CONFIG_IA32_EMULATION
 189         unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);
 190         unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);
 191         unsafe_put_user(get_user_seg(es), (unsigned int __user *)&sc->es, Efault);
 192 #else
 193         unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
 194         unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
 195         unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
 196 #endif
 197
 198         unsafe_put_user(regs->di, &sc->di, Efault);
 199         unsafe_put_user(regs->si, &sc->si, Efault);
 200         unsafe_put_user(regs->bp, &sc->bp, Efault);
 201         unsafe_put_user(regs->sp, &sc->sp, Efault);
 202         unsafe_put_user(regs->bx, &sc->bx, Efault);
 203         unsafe_put_user(regs->dx, &sc->dx, Efault);
 204         unsafe_put_user(regs->cx, &sc->cx, Efault);
 205         unsafe_put_user(regs->ax, &sc->ax, Efault);
 206         unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
 207         unsafe_put_user(current->thread.error_code, &sc->err, Efault);
 208         unsafe_put_user(regs->ip, &sc->ip, Efault);
 209         unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
 210         unsafe_put_user(regs->flags, &sc->flags, Efault);
 211         unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
 212         unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
 213
 214         unsafe_put_user(ptr_to_compat(fpstate), &sc->fpstate, Efault);
 215
 216         /* non-iBCS2 extensions.. */
 217         unsafe_put_user(mask, &sc->oldmask, Efault);
 218         unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
 219         return 0;
 220
 221 Efault:
 222         return -EFAULT;
 223 }
 224
 225 #define unsafe_put_sigcontext32(sc, fp, regs, set, label)               \
 226 do {                                                                    \
 227         if (__unsafe_setup_sigcontext32(sc, fp, regs, set->sig[0]))     \
 228                 goto label;                                             \
 229 } while(0)
 230
 231 int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs)
 232 {
 233         sigset32_t *set = (sigset32_t *) sigmask_to_save();
 234         struct sigframe_ia32 __user *frame;
 235         void __user *restorer;
 236         void __user *fp = NULL;
 237
 238         /* copy_to_user optimizes that into a single 8 byte store */
 239         static const struct {
 240                 u16 poplmovl;
 241                 u32 val;
 242                 u16 int80;
 243         } __attribute__((packed)) code = {
 244                 0xb858,          /* popl %eax ; movl $...,%eax */
 245                 __NR_ia32_sigreturn,
 246                 0x80cd,         /* int $0x80 */
 247         };
 248
 249         frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
 250
 251         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 252                 restorer = ksig->ka.sa.sa_restorer;
 253         } else {
 254                 /* Return stub is in 32bit vsyscall page */
 255                 if (current->mm->context.vdso)
 256                         restorer = current->mm->context.vdso +
 257                                 vdso_image_32.sym___kernel_sigreturn;
 258                 else
 259                         restorer = &frame->retcode;
 260         }
 261
 262         if (!user_access_begin(frame, sizeof(*frame)))
 263                 return -EFAULT;
 264
 265         unsafe_put_user(ksig->sig, &frame->sig, Efault);
 266         unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault);
 267         unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
 268         unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
 269         /*
 270          * These are actually not used anymore, but left because some
 271          * gdb versions depend on them as a marker.
 272          */
 273         unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
 274         user_access_end();
 275
 276         /* Set up registers for signal handler */
 277         regs->sp = (unsigned long) frame;
 278         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 279
 280         /* Make -mregparm=3 work */
 281         regs->ax = ksig->sig;
 282         regs->dx = 0;
 283         regs->cx = 0;
 284
 285 #ifdef CONFIG_IA32_EMULATION
 286         loadsegment(ds, __USER_DS);
 287         loadsegment(es, __USER_DS);
 288 #else
 289         regs->ds = __USER_DS;
 290         regs->es = __USER_DS;
 291 #endif
 292
 293         regs->cs = __USER32_CS;
 294         regs->ss = __USER_DS;
 295
 296         return 0;
 297 Efault:
 298         user_access_end();
 299         return -EFAULT;
 300 }
 301
 302 int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 303 {
 304         sigset32_t *set = (sigset32_t *) sigmask_to_save();
 305         struct rt_sigframe_ia32 __user *frame;
 306         void __user *restorer;
 307         void __user *fp = NULL;
 308
 309         /* unsafe_put_user optimizes that into a single 8 byte store */
 310         static const struct {
 311                 u8 movl;
 312                 u32 val;
 313                 u16 int80;
 314                 u8  pad;
 315         } __attribute__((packed)) code = {
 316                 0xb8,
 317                 __NR_ia32_rt_sigreturn,
 318                 0x80cd,
 319                 0,
 320         };
 321
 322         frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
 323
 324         if (!user_access_begin(frame, sizeof(*frame)))
 325                 return -EFAULT;
 326
 327         unsafe_put_user(ksig->sig, &frame->sig, Efault);
 328         unsafe_put_user(ptr_to_compat(&frame->info), &frame->pinfo, Efault);
 329         unsafe_put_user(ptr_to_compat(&frame->uc), &frame->puc, Efault);
 330
 331         /* Create the ucontext.  */
 332         if (static_cpu_has(X86_FEATURE_XSAVE))
 333                 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
 334         else
 335                 unsafe_put_user(0, &frame->uc.uc_flags, Efault);
 336         unsafe_put_user(0, &frame->uc.uc_link, Efault);
 337         unsafe_save_altstack32(&frame->uc.uc_stack, regs->sp, Efault);
 338
 339         if (ksig->ka.sa.sa_flags & SA_RESTORER)
 340                 restorer = ksig->ka.sa.sa_restorer;
 341         else
 342                 restorer = current->mm->context.vdso +
 343                         vdso_image_32.sym___kernel_rt_sigreturn;
 344         unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
 345
 346         /*
 347          * Not actually used anymore, but left because some gdb
 348          * versions need it.
 349          */
 350         unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
 351         unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
 352         unsafe_put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask, Efault);
 353         user_access_end();
 354
 355         if (__copy_siginfo_to_user32(&frame->info, &ksig->info))
 356                 return -EFAULT;
 357
 358         /* Set up registers for signal handler */
 359         regs->sp = (unsigned long) frame;
 360         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 361
 362         /* Make -mregparm=3 work */
 363         regs->ax = ksig->sig;
 364         regs->dx = (unsigned long) &frame->info;
 365         regs->cx = (unsigned long) &frame->uc;
 366
 367 #ifdef CONFIG_IA32_EMULATION
 368         loadsegment(ds, __USER_DS);
 369         loadsegment(es, __USER_DS);
 370 #else
 371         regs->ds = __USER_DS;
 372         regs->es = __USER_DS;
 373 #endif
 374
 375         regs->cs = __USER32_CS;
 376         regs->ss = __USER_DS;
 377
 378         return 0;
 379 Efault:
 380         user_access_end();
 381         return -EFAULT;
 382 }
 383
 384 /*
 385  * The siginfo_t structure and handing code is very easy
 386  * to break in several ways.  It must always be updated when new
 387  * updates are made to the main siginfo_t, and
 388  * copy_siginfo_to_user32() must be updated when the
 389  * (arch-independent) copy_siginfo_to_user() is updated.
 390  *
 391  * It is also easy to put a new member in the siginfo_t
 392  * which has implicit alignment which can move internal structure
 393  * alignment around breaking the ABI.  This can happen if you,
 394  * for instance, put a plain 64-bit value in there.
 395  */
 396
 397 /*
 398 * If adding a new si_code, there is probably new data in
 399 * the siginfo.  Make sure folks bumping the si_code
 400 * limits also have to look at this code.  Make sure any
 401 * new fields are handled in copy_siginfo_to_user32()!
 402 */
 403 static_assert(NSIGILL  == 11);
 404 static_assert(NSIGFPE  == 15);
 405 static_assert(NSIGSEGV == 10);
 406 static_assert(NSIGBUS  == 5);
 407 static_assert(NSIGTRAP == 6);
 408 static_assert(NSIGCHLD == 6);
 409 static_assert(NSIGSYS  == 2);
 410
 411 /* This is part of the ABI and can never change in size: */
 412 static_assert(sizeof(siginfo32_t) == 128);
 413
 414 /* This is a part of the ABI and can never change in alignment */
 415 static_assert(__alignof__(siginfo32_t) == 4);
 416
 417 /*
 418 * The offsets of all the (unioned) si_fields are fixed
 419 * in the ABI, of course.  Make sure none of them ever
 420 * move and are always at the beginning:
 421 */
 422 static_assert(offsetof(siginfo32_t, _sifields) == 3 * sizeof(int));
 423
 424 static_assert(offsetof(siginfo32_t, si_signo) == 0);
 425 static_assert(offsetof(siginfo32_t, si_errno) == 4);
 426 static_assert(offsetof(siginfo32_t, si_code)  == 8);
 427
 428 /*
 429 * Ensure that the size of each si_field never changes.
 430 * If it does, it is a sign that the
 431 * copy_siginfo_to_user32() code below needs to updated
 432 * along with the size in the CHECK_SI_SIZE().
 433 *
 434 * We repeat this check for both the generic and compat
 435 * siginfos.
 436 *
 437 * Note: it is OK for these to grow as long as the whole
 438 * structure stays within the padding size (checked
 439 * above).
 440 */
 441
 442 #define CHECK_SI_OFFSET(name)                                           \
 443         static_assert(offsetof(siginfo32_t, _sifields) ==               \
 444                       offsetof(siginfo32_t, _sifields.name))
 445
 446 #define CHECK_SI_SIZE(name, size)                                       \
 447         static_assert(sizeof_field(siginfo32_t, _sifields.name) == size)
 448
 449 CHECK_SI_OFFSET(_kill);
 450 CHECK_SI_SIZE  (_kill, 2*sizeof(int));
 451 static_assert(offsetof(siginfo32_t, si_pid) == 0xC);
 452 static_assert(offsetof(siginfo32_t, si_uid) == 0x10);
 453
 454 CHECK_SI_OFFSET(_timer);
 455 #ifdef CONFIG_COMPAT
 456 /* compat_siginfo_t doesn't have si_sys_private */
 457 CHECK_SI_SIZE  (_timer, 3*sizeof(int));
 458 #else
 459 CHECK_SI_SIZE  (_timer, 4*sizeof(int));
 460 #endif
 461 static_assert(offsetof(siginfo32_t, si_tid)     == 0x0C);
 462 static_assert(offsetof(siginfo32_t, si_overrun) == 0x10);
 463 static_assert(offsetof(siginfo32_t, si_value)   == 0x14);
 464
 465 CHECK_SI_OFFSET(_rt);
 466 CHECK_SI_SIZE  (_rt, 3*sizeof(int));
 467 static_assert(offsetof(siginfo32_t, si_pid)   == 0x0C);
 468 static_assert(offsetof(siginfo32_t, si_uid)   == 0x10);
 469 static_assert(offsetof(siginfo32_t, si_value) == 0x14);
 470
 471 CHECK_SI_OFFSET(_sigchld);
 472 CHECK_SI_SIZE  (_sigchld, 5*sizeof(int));
 473 static_assert(offsetof(siginfo32_t, si_pid)    == 0x0C);
 474 static_assert(offsetof(siginfo32_t, si_uid)    == 0x10);
 475 static_assert(offsetof(siginfo32_t, si_status) == 0x14);
 476 static_assert(offsetof(siginfo32_t, si_utime)  == 0x18);
 477 static_assert(offsetof(siginfo32_t, si_stime)  == 0x1C);
 478
 479 CHECK_SI_OFFSET(_sigfault);
 480 CHECK_SI_SIZE  (_sigfault, 4*sizeof(int));
 481 static_assert(offsetof(siginfo32_t, si_addr) == 0x0C);
 482
 483 static_assert(offsetof(siginfo32_t, si_trapno) == 0x10);
 484
 485 static_assert(offsetof(siginfo32_t, si_addr_lsb) == 0x10);
 486
 487 static_assert(offsetof(siginfo32_t, si_lower) == 0x14);
 488 static_assert(offsetof(siginfo32_t, si_upper) == 0x18);
 489
 490 static_assert(offsetof(siginfo32_t, si_pkey) == 0x14);
 491
 492 static_assert(offsetof(siginfo32_t, si_perf_data) == 0x10);
 493 static_assert(offsetof(siginfo32_t, si_perf_type) == 0x14);
 494 static_assert(offsetof(siginfo32_t, si_perf_flags) == 0x18);
 495
 496 CHECK_SI_OFFSET(_sigpoll);
 497 CHECK_SI_SIZE  (_sigpoll, 2*sizeof(int));
 498 static_assert(offsetof(siginfo32_t, si_band) == 0x0C);
 499 static_assert(offsetof(siginfo32_t, si_fd)   == 0x10);
 500
 501 CHECK_SI_OFFSET(_sigsys);
 502 CHECK_SI_SIZE  (_sigsys, 3*sizeof(int));
 503 static_assert(offsetof(siginfo32_t, si_call_addr) == 0x0C);
 504 static_assert(offsetof(siginfo32_t, si_syscall)   == 0x10);
 505 static_assert(offsetof(siginfo32_t, si_arch)      == 0x14);
 506
 507 /* any new si_fields should be added here */