arch/x86/ia32/ia32_signal.c

   1 /*
   2  *  linux/arch/x86_64/ia32/ia32_signal.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   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  *  2000-12-*   x86-64 compatibility mode signal handling by Andi Kleen
   9  */
  10
  11 #include <linux/sched.h>
  12 #include <linux/mm.h>
  13 #include <linux/smp.h>
  14 #include <linux/kernel.h>
  15 #include <linux/signal.h>
  16 #include <linux/errno.h>
  17 #include <linux/wait.h>
  18 #include <linux/ptrace.h>
  19 #include <linux/unistd.h>
  20 #include <linux/stddef.h>
  21 #include <linux/personality.h>
  22 #include <linux/compat.h>
  23 #include <linux/binfmts.h>
  24 #include <asm/ucontext.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/i387.h>
  27 #include <asm/ptrace.h>
  28 #include <asm/ia32_unistd.h>
  29 #include <asm/user32.h>
  30 #include <asm/sigcontext32.h>
  31 #include <asm/proto.h>
  32 #include <asm/vdso.h>
  33 #include <asm/sigframe.h>
  34 #include <asm/sys_ia32.h>
  35
  36 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  37
  38 #define FIX_EFLAGS      (X86_EFLAGS_AC | X86_EFLAGS_OF | \
  39                          X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
  40                          X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
  41                          X86_EFLAGS_CF)
  42
  43 void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
  44
  45 int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
  46 {
  47         int err = 0;
  48
  49         if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
  50                 return -EFAULT;
  51
  52         put_user_try {
  53                 /* If you change siginfo_t structure, please make sure that
  54                    this code is fixed accordingly.
  55                    It should never copy any pad contained in the structure
  56                    to avoid security leaks, but must copy the generic
  57                    3 ints plus the relevant union member.  */
  58                 put_user_ex(from->si_signo, &to->si_signo);
  59                 put_user_ex(from->si_errno, &to->si_errno);
  60                 put_user_ex((short)from->si_code, &to->si_code);
  61
  62                 if (from->si_code < 0) {
  63                         put_user_ex(from->si_pid, &to->si_pid);
  64                         put_user_ex(from->si_uid, &to->si_uid);
  65                         put_user_ex(ptr_to_compat(from->si_ptr), &to->si_ptr);
  66                 } else {
  67                         /*
  68                          * First 32bits of unions are always present:
  69                          * si_pid === si_band === si_tid === si_addr(LS half)
  70                          */
  71                         put_user_ex(from->_sifields._pad[0],
  72                                           &to->_sifields._pad[0]);
  73                         switch (from->si_code >> 16) {
  74                         case __SI_FAULT >> 16:
  75                                 break;
  76                         case __SI_CHLD >> 16:
  77                                 put_user_ex(from->si_utime, &to->si_utime);
  78                                 put_user_ex(from->si_stime, &to->si_stime);
  79                                 put_user_ex(from->si_status, &to->si_status);
  80                                 /* FALL THROUGH */
  81                         default:
  82                         case __SI_KILL >> 16:
  83                                 put_user_ex(from->si_uid, &to->si_uid);
  84                                 break;
  85                         case __SI_POLL >> 16:
  86                                 put_user_ex(from->si_fd, &to->si_fd);
  87                                 break;
  88                         case __SI_TIMER >> 16:
  89                                 put_user_ex(from->si_overrun, &to->si_overrun);
  90                                 put_user_ex(ptr_to_compat(from->si_ptr),
  91                                             &to->si_ptr);
  92                                 break;
  93                                  /* This is not generated by the kernel as of now.  */
  94                         case __SI_RT >> 16:
  95                         case __SI_MESGQ >> 16:
  96                                 put_user_ex(from->si_uid, &to->si_uid);
  97                                 put_user_ex(from->si_int, &to->si_int);
  98                                 break;
  99                         }
 100                 }
 101         } put_user_catch(err);
 102
 103         return err;
 104 }
 105
 106 int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
 107 {
 108         int err = 0;
 109         u32 ptr32;
 110
 111         if (!access_ok(VERIFY_READ, from, sizeof(compat_siginfo_t)))
 112                 return -EFAULT;
 113
 114         get_user_try {
 115                 get_user_ex(to->si_signo, &from->si_signo);
 116                 get_user_ex(to->si_errno, &from->si_errno);
 117                 get_user_ex(to->si_code, &from->si_code);
 118
 119                 get_user_ex(to->si_pid, &from->si_pid);
 120                 get_user_ex(to->si_uid, &from->si_uid);
 121                 get_user_ex(ptr32, &from->si_ptr);
 122                 to->si_ptr = compat_ptr(ptr32);
 123         } get_user_catch(err);
 124
 125         return err;
 126 }
 127
 128 asmlinkage long sys32_sigsuspend(int history0, int history1, old_sigset_t mask)
 129 {
 130         mask &= _BLOCKABLE;
 131         spin_lock_irq(&current->sighand->siglock);
 132         current->saved_sigmask = current->blocked;
 133         siginitset(&current->blocked, mask);
 134         recalc_sigpending();
 135         spin_unlock_irq(&current->sighand->siglock);
 136
 137         current->state = TASK_INTERRUPTIBLE;
 138         schedule();
 139         set_restore_sigmask();
 140         return -ERESTARTNOHAND;
 141 }
 142
 143 asmlinkage long sys32_sigaltstack(const stack_ia32_t __user *uss_ptr,
 144                                   stack_ia32_t __user *uoss_ptr,
 145                                   struct pt_regs *regs)
 146 {
 147         stack_t uss, uoss;
 148         int ret, err = 0;
 149         mm_segment_t seg;
 150
 151         if (uss_ptr) {
 152                 u32 ptr;
 153
 154                 memset(&uss, 0, sizeof(stack_t));
 155                 if (!access_ok(VERIFY_READ, uss_ptr, sizeof(stack_ia32_t)))
 156                         return -EFAULT;
 157
 158                 get_user_try {
 159                         get_user_ex(ptr, &uss_ptr->ss_sp);
 160                         get_user_ex(uss.ss_flags, &uss_ptr->ss_flags);
 161                         get_user_ex(uss.ss_size, &uss_ptr->ss_size);
 162                 } get_user_catch(err);
 163
 164                 if (err)
 165                         return -EFAULT;
 166                 uss.ss_sp = compat_ptr(ptr);
 167         }
 168         seg = get_fs();
 169         set_fs(KERNEL_DS);
 170         ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss, regs->sp);
 171         set_fs(seg);
 172         if (ret >= 0 && uoss_ptr)  {
 173                 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(stack_ia32_t)))
 174                         return -EFAULT;
 175
 176                 put_user_try {
 177                         put_user_ex(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp);
 178                         put_user_ex(uoss.ss_flags, &uoss_ptr->ss_flags);
 179                         put_user_ex(uoss.ss_size, &uoss_ptr->ss_size);
 180                 } put_user_catch(err);
 181
 182                 if (err)
 183                         ret = -EFAULT;
 184         }
 185         return ret;
 186 }
 187
 188 /*
 189  * Do a signal return; undo the signal stack.
 190  */
 191 #define COPY(x)                 {               \
 192         get_user_ex(regs->x, &sc->x);           \
 193 }
 194
 195 #define GET_SEG(seg)            ({                      \
 196         unsigned short tmp;                             \
 197         get_user_ex(tmp, &sc->seg);                     \
 198         tmp;                                            \
 199 })
 200
 201 #define COPY_SEG_CPL3(seg)      do {                    \
 202         regs->seg = GET_SEG(seg) | 3;                   \
 203 } while (0)
 204
 205 #define RELOAD_SEG(seg)         {               \
 206         unsigned int cur, pre;                  \
 207         get_user_ex(pre, &sc->seg);             \
 208         savesegment(seg, cur);                  \
 209         pre |= 3;                               \
 210         if (pre != cur)                         \
 211                 loadsegment(seg, pre);          \
 212 }
 213
 214 static int ia32_restore_sigcontext(struct pt_regs *regs,
 215                                    struct sigcontext_ia32 __user *sc,
 216                                    unsigned int *pax)
 217 {
 218         unsigned int tmpflags, gs, oldgs, err = 0;
 219         void __user *buf;
 220         u32 tmp;
 221
 222         /* Always make any pending restarted system calls return -EINTR */
 223         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 224
 225         get_user_try {
 226                 /*
 227                  * Reload fs and gs if they have changed in the signal
 228                  * handler.  This does not handle long fs/gs base changes in
 229                  * the handler, but does not clobber them at least in the
 230                  * normal case.
 231                  */
 232                 get_user_ex(gs, &sc->gs);
 233                 gs |= 3;
 234                 savesegment(gs, oldgs);
 235                 if (gs != oldgs)
 236                         load_gs_index(gs);
 237
 238                 RELOAD_SEG(fs);
 239                 RELOAD_SEG(ds);
 240                 RELOAD_SEG(es);
 241
 242                 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 243                 COPY(dx); COPY(cx); COPY(ip);
 244                 /* Don't touch extended registers */
 245
 246                 COPY_SEG_CPL3(cs);
 247                 COPY_SEG_CPL3(ss);
 248
 249                 get_user_ex(tmpflags, &sc->flags);
 250                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 251                 /* disable syscall checks */
 252                 regs->orig_ax = -1;
 253
 254                 get_user_ex(tmp, &sc->fpstate);
 255                 buf = compat_ptr(tmp);
 256                 err |= restore_i387_xstate_ia32(buf);
 257
 258                 get_user_ex(*pax, &sc->ax);
 259         } get_user_catch(err);
 260
 261         return err;
 262 }
 263
 264 asmlinkage long sys32_sigreturn(struct pt_regs *regs)
 265 {
 266         struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
 267         sigset_t set;
 268         unsigned int ax;
 269
 270         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 271                 goto badframe;
 272         if (__get_user(set.sig[0], &frame->sc.oldmask)
 273             || (_COMPAT_NSIG_WORDS > 1
 274                 && __copy_from_user((((char *) &set.sig) + 4),
 275                                     &frame->extramask,
 276                                     sizeof(frame->extramask))))
 277                 goto badframe;
 278
 279         sigdelsetmask(&set, ~_BLOCKABLE);
 280         spin_lock_irq(&current->sighand->siglock);
 281         current->blocked = set;
 282         recalc_sigpending();
 283         spin_unlock_irq(&current->sighand->siglock);
 284
 285         if (ia32_restore_sigcontext(regs, &frame->sc, &ax))
 286                 goto badframe;
 287         return ax;
 288
 289 badframe:
 290         signal_fault(regs, frame, "32bit sigreturn");
 291         return 0;
 292 }
 293
 294 asmlinkage long sys32_rt_sigreturn(struct pt_regs *regs)
 295 {
 296         struct rt_sigframe_ia32 __user *frame;
 297         sigset_t set;
 298         unsigned int ax;
 299         struct pt_regs tregs;
 300
 301         frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
 302
 303         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 304                 goto badframe;
 305         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 306                 goto badframe;
 307
 308         sigdelsetmask(&set, ~_BLOCKABLE);
 309         spin_lock_irq(&current->sighand->siglock);
 310         current->blocked = set;
 311         recalc_sigpending();
 312         spin_unlock_irq(&current->sighand->siglock);
 313
 314         if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 315                 goto badframe;
 316
 317         tregs = *regs;
 318         if (sys32_sigaltstack(&frame->uc.uc_stack, NULL, &tregs) == -EFAULT)
 319                 goto badframe;
 320
 321         return ax;
 322
 323 badframe:
 324         signal_fault(regs, frame, "32bit rt sigreturn");
 325         return 0;
 326 }
 327
 328 /*
 329  * Set up a signal frame.
 330  */
 331
 332 static int ia32_setup_sigcontext(struct sigcontext_ia32 __user *sc,
 333                                  void __user *fpstate,
 334                                  struct pt_regs *regs, unsigned int mask)
 335 {
 336         int tmp, err = 0;
 337
 338         put_user_try {
 339                 savesegment(gs, tmp);
 340                 put_user_ex(tmp, (unsigned int __user *)&sc->gs);
 341                 savesegment(fs, tmp);
 342                 put_user_ex(tmp, (unsigned int __user *)&sc->fs);
 343                 savesegment(ds, tmp);
 344                 put_user_ex(tmp, (unsigned int __user *)&sc->ds);
 345                 savesegment(es, tmp);
 346                 put_user_ex(tmp, (unsigned int __user *)&sc->es);
 347
 348                 put_user_ex(regs->di, &sc->di);
 349                 put_user_ex(regs->si, &sc->si);
 350                 put_user_ex(regs->bp, &sc->bp);
 351                 put_user_ex(regs->sp, &sc->sp);
 352                 put_user_ex(regs->bx, &sc->bx);
 353                 put_user_ex(regs->dx, &sc->dx);
 354                 put_user_ex(regs->cx, &sc->cx);
 355                 put_user_ex(regs->ax, &sc->ax);
 356                 put_user_ex(current->thread.trap_no, &sc->trapno);
 357                 put_user_ex(current->thread.error_code, &sc->err);
 358                 put_user_ex(regs->ip, &sc->ip);
 359                 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 360                 put_user_ex(regs->flags, &sc->flags);
 361                 put_user_ex(regs->sp, &sc->sp_at_signal);
 362                 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 363
 364                 put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
 365
 366                 /* non-iBCS2 extensions.. */
 367                 put_user_ex(mask, &sc->oldmask);
 368                 put_user_ex(current->thread.cr2, &sc->cr2);
 369         } put_user_catch(err);
 370
 371         return err;
 372 }
 373
 374 /*
 375  * Determine which stack to use..
 376  */
 377 static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 378                                  size_t frame_size,
 379                                  void **fpstate)
 380 {
 381         unsigned long sp;
 382
 383         /* Default to using normal stack */
 384         sp = regs->sp;
 385
 386         /* This is the X/Open sanctioned signal stack switching.  */
 387         if (ka->sa.sa_flags & SA_ONSTACK) {
 388                 if (sas_ss_flags(sp) == 0)
 389                         sp = current->sas_ss_sp + current->sas_ss_size;
 390         }
 391
 392         /* This is the legacy signal stack switching. */
 393         else if ((regs->ss & 0xffff) != __USER32_DS &&
 394                 !(ka->sa.sa_flags & SA_RESTORER) &&
 395                  ka->sa.sa_restorer)
 396                 sp = (unsigned long) ka->sa.sa_restorer;
 397
 398         if (used_math()) {
 399                 sp = sp - sig_xstate_ia32_size;
 400                 *fpstate = (struct _fpstate_ia32 *) sp;
 401                 if (save_i387_xstate_ia32(*fpstate) < 0)
 402                         return (void __user *) -1L;
 403         }
 404
 405         sp -= frame_size;
 406         /* Align the stack pointer according to the i386 ABI,
 407          * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 408         sp = ((sp + 4) & -16ul) - 4;
 409         return (void __user *) sp;
 410 }
 411
 412 int ia32_setup_frame(int sig, struct k_sigaction *ka,
 413                      compat_sigset_t *set, struct pt_regs *regs)
 414 {
 415         struct sigframe_ia32 __user *frame;
 416         void __user *restorer;
 417         int err = 0;
 418         void __user *fpstate = NULL;
 419
 420         /* copy_to_user optimizes that into a single 8 byte store */
 421         static const struct {
 422                 u16 poplmovl;
 423                 u32 val;
 424                 u16 int80;
 425         } __attribute__((packed)) code = {
 426                 0xb858,          /* popl %eax ; movl $...,%eax */
 427                 __NR_ia32_sigreturn,
 428                 0x80cd,         /* int $0x80 */
 429         };
 430
 431         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 432
 433         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 434                 return -EFAULT;
 435
 436         if (__put_user(sig, &frame->sig))
 437                 return -EFAULT;
 438
 439         if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 440                 return -EFAULT;
 441
 442         if (_COMPAT_NSIG_WORDS > 1) {
 443                 if (__copy_to_user(frame->extramask, &set->sig[1],
 444                                    sizeof(frame->extramask)))
 445                         return -EFAULT;
 446         }
 447
 448         if (ka->sa.sa_flags & SA_RESTORER) {
 449                 restorer = ka->sa.sa_restorer;
 450         } else {
 451                 /* Return stub is in 32bit vsyscall page */
 452                 if (current->mm->context.vdso)
 453                         restorer = VDSO32_SYMBOL(current->mm->context.vdso,
 454                                                  sigreturn);
 455                 else
 456                         restorer = &frame->retcode;
 457         }
 458
 459         put_user_try {
 460                 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 461
 462                 /*
 463                  * These are actually not used anymore, but left because some
 464                  * gdb versions depend on them as a marker.
 465                  */
 466                 put_user_ex(*((u64 *)&code), (u64 *)frame->retcode);
 467         } put_user_catch(err);
 468
 469         if (err)
 470                 return -EFAULT;
 471
 472         /* Set up registers for signal handler */
 473         regs->sp = (unsigned long) frame;
 474         regs->ip = (unsigned long) ka->sa.sa_handler;
 475
 476         /* Make -mregparm=3 work */
 477         regs->ax = sig;
 478         regs->dx = 0;
 479         regs->cx = 0;
 480
 481         loadsegment(ds, __USER32_DS);
 482         loadsegment(es, __USER32_DS);
 483
 484         regs->cs = __USER32_CS;
 485         regs->ss = __USER32_DS;
 486
 487         return 0;
 488 }
 489
 490 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 491                         compat_sigset_t *set, struct pt_regs *regs)
 492 {
 493         struct rt_sigframe_ia32 __user *frame;
 494         void __user *restorer;
 495         int err = 0;
 496         void __user *fpstate = NULL;
 497
 498         /* __copy_to_user optimizes that into a single 8 byte store */
 499         static const struct {
 500                 u8 movl;
 501                 u32 val;
 502                 u16 int80;
 503                 u8  pad;
 504         } __attribute__((packed)) code = {
 505                 0xb8,
 506                 __NR_ia32_rt_sigreturn,
 507                 0x80cd,
 508                 0,
 509         };
 510
 511         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 512
 513         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 514                 return -EFAULT;
 515
 516         put_user_try {
 517                 put_user_ex(sig, &frame->sig);
 518                 put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
 519                 put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
 520                 err |= copy_siginfo_to_user32(&frame->info, info);
 521
 522                 /* Create the ucontext.  */
 523                 if (cpu_has_xsave)
 524                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 525                 else
 526                         put_user_ex(0, &frame->uc.uc_flags);
 527                 put_user_ex(0, &frame->uc.uc_link);
 528                 put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 529                 put_user_ex(sas_ss_flags(regs->sp),
 530                             &frame->uc.uc_stack.ss_flags);
 531                 put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 532                 err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 533                                              regs, set->sig[0]);
 534                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 535
 536                 if (ka->sa.sa_flags & SA_RESTORER)
 537                         restorer = ka->sa.sa_restorer;
 538                 else
 539                         restorer = VDSO32_SYMBOL(current->mm->context.vdso,
 540                                                  rt_sigreturn);
 541                 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 542
 543                 /*
 544                  * Not actually used anymore, but left because some gdb
 545                  * versions need it.
 546                  */
 547                 put_user_ex(*((u64 *)&code), (u64 *)frame->retcode);
 548         } put_user_catch(err);
 549
 550         if (err)
 551                 return -EFAULT;
 552
 553         /* Set up registers for signal handler */
 554         regs->sp = (unsigned long) frame;
 555         regs->ip = (unsigned long) ka->sa.sa_handler;
 556
 557         /* Make -mregparm=3 work */
 558         regs->ax = sig;
 559         regs->dx = (unsigned long) &frame->info;
 560         regs->cx = (unsigned long) &frame->uc;
 561
 562         loadsegment(ds, __USER32_DS);
 563         loadsegment(es, __USER32_DS);
 564
 565         regs->cs = __USER32_CS;
 566         regs->ss = __USER32_DS;
 567
 568         return 0;
 569 }