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         sigset_t blocked;
 131
 132         current->saved_sigmask = current->blocked;
 133
 134         mask &= _BLOCKABLE;
 135         siginitset(&blocked, mask);
 136         set_current_blocked(&blocked);
 137
 138         current->state = TASK_INTERRUPTIBLE;
 139         schedule();
 140
 141         set_restore_sigmask();
 142         return -ERESTARTNOHAND;
 143 }
 144
 145 asmlinkage long sys32_sigaltstack(const stack_ia32_t __user *uss_ptr,
 146                                   stack_ia32_t __user *uoss_ptr,
 147                                   struct pt_regs *regs)
 148 {
 149         stack_t uss, uoss;
 150         int ret, err = 0;
 151         mm_segment_t seg;
 152
 153         if (uss_ptr) {
 154                 u32 ptr;
 155
 156                 memset(&uss, 0, sizeof(stack_t));
 157                 if (!access_ok(VERIFY_READ, uss_ptr, sizeof(stack_ia32_t)))
 158                         return -EFAULT;
 159
 160                 get_user_try {
 161                         get_user_ex(ptr, &uss_ptr->ss_sp);
 162                         get_user_ex(uss.ss_flags, &uss_ptr->ss_flags);
 163                         get_user_ex(uss.ss_size, &uss_ptr->ss_size);
 164                 } get_user_catch(err);
 165
 166                 if (err)
 167                         return -EFAULT;
 168                 uss.ss_sp = compat_ptr(ptr);
 169         }
 170         seg = get_fs();
 171         set_fs(KERNEL_DS);
 172         ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss, regs->sp);
 173         set_fs(seg);
 174         if (ret >= 0 && uoss_ptr)  {
 175                 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(stack_ia32_t)))
 176                         return -EFAULT;
 177
 178                 put_user_try {
 179                         put_user_ex(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp);
 180                         put_user_ex(uoss.ss_flags, &uoss_ptr->ss_flags);
 181                         put_user_ex(uoss.ss_size, &uoss_ptr->ss_size);
 182                 } put_user_catch(err);
 183
 184                 if (err)
 185                         ret = -EFAULT;
 186         }
 187         return ret;
 188 }
 189
 190 /*
 191  * Do a signal return; undo the signal stack.
 192  */
 193 #define loadsegment_gs(v)       load_gs_index(v)
 194 #define loadsegment_fs(v)       loadsegment(fs, v)
 195 #define loadsegment_ds(v)       loadsegment(ds, v)
 196 #define loadsegment_es(v)       loadsegment(es, v)
 197
 198 #define get_user_seg(seg)       ({ unsigned int v; savesegment(seg, v); v; })
 199 #define set_user_seg(seg, v)    loadsegment_##seg(v)
 200
 201 #define COPY(x)                 {               \
 202         get_user_ex(regs->x, &sc->x);           \
 203 }
 204
 205 #define GET_SEG(seg)            ({                      \
 206         unsigned short tmp;                             \
 207         get_user_ex(tmp, &sc->seg);                     \
 208         tmp;                                            \
 209 })
 210
 211 #define COPY_SEG_CPL3(seg)      do {                    \
 212         regs->seg = GET_SEG(seg) | 3;                   \
 213 } while (0)
 214
 215 #define RELOAD_SEG(seg)         {               \
 216         unsigned int pre = GET_SEG(seg);        \
 217         unsigned int cur = get_user_seg(seg);   \
 218         pre |= 3;                               \
 219         if (pre != cur)                         \
 220                 set_user_seg(seg, pre);         \
 221 }
 222
 223 static int ia32_restore_sigcontext(struct pt_regs *regs,
 224                                    struct sigcontext_ia32 __user *sc,
 225                                    unsigned int *pax)
 226 {
 227         unsigned int tmpflags, err = 0;
 228         void __user *buf;
 229         u32 tmp;
 230
 231         /* Always make any pending restarted system calls return -EINTR */
 232         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 233
 234         get_user_try {
 235                 /*
 236                  * Reload fs and gs if they have changed in the signal
 237                  * handler.  This does not handle long fs/gs base changes in
 238                  * the handler, but does not clobber them at least in the
 239                  * normal case.
 240                  */
 241                 RELOAD_SEG(gs);
 242                 RELOAD_SEG(fs);
 243                 RELOAD_SEG(ds);
 244                 RELOAD_SEG(es);
 245
 246                 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 247                 COPY(dx); COPY(cx); COPY(ip);
 248                 /* Don't touch extended registers */
 249
 250                 COPY_SEG_CPL3(cs);
 251                 COPY_SEG_CPL3(ss);
 252
 253                 get_user_ex(tmpflags, &sc->flags);
 254                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 255                 /* disable syscall checks */
 256                 regs->orig_ax = -1;
 257
 258                 get_user_ex(tmp, &sc->fpstate);
 259                 buf = compat_ptr(tmp);
 260                 err |= restore_i387_xstate_ia32(buf);
 261
 262                 get_user_ex(*pax, &sc->ax);
 263         } get_user_catch(err);
 264
 265         return err;
 266 }
 267
 268 asmlinkage long sys32_sigreturn(struct pt_regs *regs)
 269 {
 270         struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
 271         sigset_t set;
 272         unsigned int ax;
 273
 274         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 275                 goto badframe;
 276         if (__get_user(set.sig[0], &frame->sc.oldmask)
 277             || (_COMPAT_NSIG_WORDS > 1
 278                 && __copy_from_user((((char *) &set.sig) + 4),
 279                                     &frame->extramask,
 280                                     sizeof(frame->extramask))))
 281                 goto badframe;
 282
 283         sigdelsetmask(&set, ~_BLOCKABLE);
 284         set_current_blocked(&set);
 285
 286         if (ia32_restore_sigcontext(regs, &frame->sc, &ax))
 287                 goto badframe;
 288         return ax;
 289
 290 badframe:
 291         signal_fault(regs, frame, "32bit sigreturn");
 292         return 0;
 293 }
 294
 295 asmlinkage long sys32_rt_sigreturn(struct pt_regs *regs)
 296 {
 297         struct rt_sigframe_ia32 __user *frame;
 298         sigset_t set;
 299         unsigned int ax;
 300         struct pt_regs tregs;
 301
 302         frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
 303
 304         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 305                 goto badframe;
 306         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 307                 goto badframe;
 308
 309         sigdelsetmask(&set, ~_BLOCKABLE);
 310         set_current_blocked(&set);
 311
 312         if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 313                 goto badframe;
 314
 315         tregs = *regs;
 316         if (sys32_sigaltstack(&frame->uc.uc_stack, NULL, &tregs) == -EFAULT)
 317                 goto badframe;
 318
 319         return ax;
 320
 321 badframe:
 322         signal_fault(regs, frame, "32bit rt sigreturn");
 323         return 0;
 324 }
 325
 326 /*
 327  * Set up a signal frame.
 328  */
 329
 330 static int ia32_setup_sigcontext(struct sigcontext_ia32 __user *sc,
 331                                  void __user *fpstate,
 332                                  struct pt_regs *regs, unsigned int mask)
 333 {
 334         int err = 0;
 335
 336         put_user_try {
 337                 put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
 338                 put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
 339                 put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
 340                 put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);
 341
 342                 put_user_ex(regs->di, &sc->di);
 343                 put_user_ex(regs->si, &sc->si);
 344                 put_user_ex(regs->bp, &sc->bp);
 345                 put_user_ex(regs->sp, &sc->sp);
 346                 put_user_ex(regs->bx, &sc->bx);
 347                 put_user_ex(regs->dx, &sc->dx);
 348                 put_user_ex(regs->cx, &sc->cx);
 349                 put_user_ex(regs->ax, &sc->ax);
 350                 put_user_ex(current->thread.trap_no, &sc->trapno);
 351                 put_user_ex(current->thread.error_code, &sc->err);
 352                 put_user_ex(regs->ip, &sc->ip);
 353                 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 354                 put_user_ex(regs->flags, &sc->flags);
 355                 put_user_ex(regs->sp, &sc->sp_at_signal);
 356                 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 357
 358                 put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
 359
 360                 /* non-iBCS2 extensions.. */
 361                 put_user_ex(mask, &sc->oldmask);
 362                 put_user_ex(current->thread.cr2, &sc->cr2);
 363         } put_user_catch(err);
 364
 365         return err;
 366 }
 367
 368 /*
 369  * Determine which stack to use..
 370  */
 371 static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 372                                  size_t frame_size,
 373                                  void **fpstate)
 374 {
 375         unsigned long sp;
 376
 377         /* Default to using normal stack */
 378         sp = regs->sp;
 379
 380         /* This is the X/Open sanctioned signal stack switching.  */
 381         if (ka->sa.sa_flags & SA_ONSTACK) {
 382                 if (sas_ss_flags(sp) == 0)
 383                         sp = current->sas_ss_sp + current->sas_ss_size;
 384         }
 385
 386         /* This is the legacy signal stack switching. */
 387         else if ((regs->ss & 0xffff) != __USER32_DS &&
 388                 !(ka->sa.sa_flags & SA_RESTORER) &&
 389                  ka->sa.sa_restorer)
 390                 sp = (unsigned long) ka->sa.sa_restorer;
 391
 392         if (used_math()) {
 393                 sp = sp - sig_xstate_ia32_size;
 394                 *fpstate = (struct _fpstate_ia32 *) sp;
 395                 if (save_i387_xstate_ia32(*fpstate) < 0)
 396                         return (void __user *) -1L;
 397         }
 398
 399         sp -= frame_size;
 400         /* Align the stack pointer according to the i386 ABI,
 401          * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 402         sp = ((sp + 4) & -16ul) - 4;
 403         return (void __user *) sp;
 404 }
 405
 406 int ia32_setup_frame(int sig, struct k_sigaction *ka,
 407                      compat_sigset_t *set, struct pt_regs *regs)
 408 {
 409         struct sigframe_ia32 __user *frame;
 410         void __user *restorer;
 411         int err = 0;
 412         void __user *fpstate = NULL;
 413
 414         /* copy_to_user optimizes that into a single 8 byte store */
 415         static const struct {
 416                 u16 poplmovl;
 417                 u32 val;
 418                 u16 int80;
 419         } __attribute__((packed)) code = {
 420                 0xb858,          /* popl %eax ; movl $...,%eax */
 421                 __NR_ia32_sigreturn,
 422                 0x80cd,         /* int $0x80 */
 423         };
 424
 425         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 426
 427         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 428                 return -EFAULT;
 429
 430         if (__put_user(sig, &frame->sig))
 431                 return -EFAULT;
 432
 433         if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 434                 return -EFAULT;
 435
 436         if (_COMPAT_NSIG_WORDS > 1) {
 437                 if (__copy_to_user(frame->extramask, &set->sig[1],
 438                                    sizeof(frame->extramask)))
 439                         return -EFAULT;
 440         }
 441
 442         if (ka->sa.sa_flags & SA_RESTORER) {
 443                 restorer = ka->sa.sa_restorer;
 444         } else {
 445                 /* Return stub is in 32bit vsyscall page */
 446                 if (current->mm->context.vdso)
 447                         restorer = VDSO32_SYMBOL(current->mm->context.vdso,
 448                                                  sigreturn);
 449                 else
 450                         restorer = &frame->retcode;
 451         }
 452
 453         put_user_try {
 454                 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 455
 456                 /*
 457                  * These are actually not used anymore, but left because some
 458                  * gdb versions depend on them as a marker.
 459                  */
 460                 put_user_ex(*((u64 *)&code), (u64 *)frame->retcode);
 461         } put_user_catch(err);
 462
 463         if (err)
 464                 return -EFAULT;
 465
 466         /* Set up registers for signal handler */
 467         regs->sp = (unsigned long) frame;
 468         regs->ip = (unsigned long) ka->sa.sa_handler;
 469
 470         /* Make -mregparm=3 work */
 471         regs->ax = sig;
 472         regs->dx = 0;
 473         regs->cx = 0;
 474
 475         loadsegment(ds, __USER32_DS);
 476         loadsegment(es, __USER32_DS);
 477
 478         regs->cs = __USER32_CS;
 479         regs->ss = __USER32_DS;
 480
 481         return 0;
 482 }
 483
 484 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 485                         compat_sigset_t *set, struct pt_regs *regs)
 486 {
 487         struct rt_sigframe_ia32 __user *frame;
 488         void __user *restorer;
 489         int err = 0;
 490         void __user *fpstate = NULL;
 491
 492         /* __copy_to_user optimizes that into a single 8 byte store */
 493         static const struct {
 494                 u8 movl;
 495                 u32 val;
 496                 u16 int80;
 497                 u8  pad;
 498         } __attribute__((packed)) code = {
 499                 0xb8,
 500                 __NR_ia32_rt_sigreturn,
 501                 0x80cd,
 502                 0,
 503         };
 504
 505         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 506
 507         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 508                 return -EFAULT;
 509
 510         put_user_try {
 511                 put_user_ex(sig, &frame->sig);
 512                 put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
 513                 put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
 514                 err |= copy_siginfo_to_user32(&frame->info, info);
 515
 516                 /* Create the ucontext.  */
 517                 if (cpu_has_xsave)
 518                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 519                 else
 520                         put_user_ex(0, &frame->uc.uc_flags);
 521                 put_user_ex(0, &frame->uc.uc_link);
 522                 put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 523                 put_user_ex(sas_ss_flags(regs->sp),
 524                             &frame->uc.uc_stack.ss_flags);
 525                 put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 526                 err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 527                                              regs, set->sig[0]);
 528                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 529
 530                 if (ka->sa.sa_flags & SA_RESTORER)
 531                         restorer = ka->sa.sa_restorer;
 532                 else
 533                         restorer = VDSO32_SYMBOL(current->mm->context.vdso,
 534                                                  rt_sigreturn);
 535                 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 536
 537                 /*
 538                  * Not actually used anymore, but left because some gdb
 539                  * versions need it.
 540                  */
 541                 put_user_ex(*((u64 *)&code), (u64 *)frame->retcode);
 542         } put_user_catch(err);
 543
 544         if (err)
 545                 return -EFAULT;
 546
 547         /* Set up registers for signal handler */
 548         regs->sp = (unsigned long) frame;
 549         regs->ip = (unsigned long) ka->sa.sa_handler;
 550
 551         /* Make -mregparm=3 work */
 552         regs->ax = sig;
 553         regs->dx = (unsigned long) &frame->info;
 554         regs->cx = (unsigned long) &frame->uc;
 555
 556         loadsegment(ds, __USER32_DS);
 557         loadsegment(es, __USER32_DS);
 558
 559         regs->cs = __USER32_CS;
 560         regs->ss = __USER32_DS;
 561
 562         return 0;
 563 }