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/ia32.h>
  28 #include <asm/ptrace.h>
  29 #include <asm/ia32_unistd.h>
  30 #include <asm/user32.h>
  31 #include <asm/sigcontext32.h>
  32 #include <asm/proto.h>
  33 #include <asm/vdso.h>
  34
  35 #define DEBUG_SIG 0
  36
  37 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  38
  39 asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);
  40 void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
  41
  42 int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
  43 {
  44         int err;
  45
  46         if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
  47                 return -EFAULT;
  48
  49         /* If you change siginfo_t structure, please make sure that
  50            this code is fixed accordingly.
  51            It should never copy any pad contained in the structure
  52            to avoid security leaks, but must copy the generic
  53            3 ints plus the relevant union member.  */
  54         err = __put_user(from->si_signo, &to->si_signo);
  55         err |= __put_user(from->si_errno, &to->si_errno);
  56         err |= __put_user((short)from->si_code, &to->si_code);
  57
  58         if (from->si_code < 0) {
  59                 err |= __put_user(from->si_pid, &to->si_pid);
  60                 err |= __put_user(from->si_uid, &to->si_uid);
  61                 err |= __put_user(ptr_to_compat(from->si_ptr), &to->si_ptr);
  62         } else {
  63                 /*
  64                  * First 32bits of unions are always present:
  65                  * si_pid === si_band === si_tid === si_addr(LS half)
  66                  */
  67                 err |= __put_user(from->_sifields._pad[0],
  68                                   &to->_sifields._pad[0]);
  69                 switch (from->si_code >> 16) {
  70                 case __SI_FAULT >> 16:
  71                         break;
  72                 case __SI_CHLD >> 16:
  73                         err |= __put_user(from->si_utime, &to->si_utime);
  74                         err |= __put_user(from->si_stime, &to->si_stime);
  75                         err |= __put_user(from->si_status, &to->si_status);
  76                         /* FALL THROUGH */
  77                 default:
  78                 case __SI_KILL >> 16:
  79                         err |= __put_user(from->si_uid, &to->si_uid);
  80                         break;
  81                 case __SI_POLL >> 16:
  82                         err |= __put_user(from->si_fd, &to->si_fd);
  83                         break;
  84                 case __SI_TIMER >> 16:
  85                         err |= __put_user(from->si_overrun, &to->si_overrun);
  86                         err |= __put_user(ptr_to_compat(from->si_ptr),
  87                                           &to->si_ptr);
  88                         break;
  89                          /* This is not generated by the kernel as of now.  */
  90                 case __SI_RT >> 16:
  91                 case __SI_MESGQ >> 16:
  92                         err |= __put_user(from->si_uid, &to->si_uid);
  93                         err |= __put_user(from->si_int, &to->si_int);
  94                         break;
  95                 }
  96         }
  97         return err;
  98 }
  99
 100 int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
 101 {
 102         int err;
 103         u32 ptr32;
 104
 105         if (!access_ok(VERIFY_READ, from, sizeof(compat_siginfo_t)))
 106                 return -EFAULT;
 107
 108         err = __get_user(to->si_signo, &from->si_signo);
 109         err |= __get_user(to->si_errno, &from->si_errno);
 110         err |= __get_user(to->si_code, &from->si_code);
 111
 112         err |= __get_user(to->si_pid, &from->si_pid);
 113         err |= __get_user(to->si_uid, &from->si_uid);
 114         err |= __get_user(ptr32, &from->si_ptr);
 115         to->si_ptr = compat_ptr(ptr32);
 116
 117         return err;
 118 }
 119
 120 asmlinkage long sys32_sigsuspend(int history0, int history1, old_sigset_t mask)
 121 {
 122         mask &= _BLOCKABLE;
 123         spin_lock_irq(&current->sighand->siglock);
 124         current->saved_sigmask = current->blocked;
 125         siginitset(&current->blocked, mask);
 126         recalc_sigpending();
 127         spin_unlock_irq(&current->sighand->siglock);
 128
 129         current->state = TASK_INTERRUPTIBLE;
 130         schedule();
 131         set_restore_sigmask();
 132         return -ERESTARTNOHAND;
 133 }
 134
 135 asmlinkage long sys32_sigaltstack(const stack_ia32_t __user *uss_ptr,
 136                                   stack_ia32_t __user *uoss_ptr,
 137                                   struct pt_regs *regs)
 138 {
 139         stack_t uss, uoss;
 140         int ret;
 141         mm_segment_t seg;
 142
 143         if (uss_ptr) {
 144                 u32 ptr;
 145
 146                 memset(&uss, 0, sizeof(stack_t));
 147                 if (!access_ok(VERIFY_READ, uss_ptr, sizeof(stack_ia32_t)) ||
 148                             __get_user(ptr, &uss_ptr->ss_sp) ||
 149                             __get_user(uss.ss_flags, &uss_ptr->ss_flags) ||
 150                             __get_user(uss.ss_size, &uss_ptr->ss_size))
 151                         return -EFAULT;
 152                 uss.ss_sp = compat_ptr(ptr);
 153         }
 154         seg = get_fs();
 155         set_fs(KERNEL_DS);
 156         ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss, regs->sp);
 157         set_fs(seg);
 158         if (ret >= 0 && uoss_ptr)  {
 159                 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(stack_ia32_t)) ||
 160                     __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
 161                     __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
 162                     __put_user(uoss.ss_size, &uoss_ptr->ss_size))
 163                         ret = -EFAULT;
 164         }
 165         return ret;
 166 }
 167
 168 /*
 169  * Do a signal return; undo the signal stack.
 170  */
 171
 172 struct sigframe
 173 {
 174         u32 pretcode;
 175         int sig;
 176         struct sigcontext_ia32 sc;
 177         struct _fpstate_ia32 fpstate;
 178         unsigned int extramask[_COMPAT_NSIG_WORDS-1];
 179         char retcode[8];
 180 };
 181
 182 struct rt_sigframe
 183 {
 184         u32 pretcode;
 185         int sig;
 186         u32 pinfo;
 187         u32 puc;
 188         compat_siginfo_t info;
 189         struct ucontext_ia32 uc;
 190         struct _fpstate_ia32 fpstate;
 191         char retcode[8];
 192 };
 193
 194 #define COPY(x)         {               \
 195         unsigned int reg;               \
 196         err |= __get_user(reg, &sc->x); \
 197         regs->x = reg;                  \
 198 }
 199
 200 #define RELOAD_SEG(seg,mask)                                            \
 201         { unsigned int cur;                                             \
 202           unsigned short pre;                                           \
 203           err |= __get_user(pre, &sc->seg);                             \
 204           asm volatile("movl %%" #seg ",%0" : "=r" (cur));              \
 205           pre |= mask;                                                  \
 206           if (pre != cur) loadsegment(seg, pre); }
 207
 208 static int ia32_restore_sigcontext(struct pt_regs *regs,
 209                                    struct sigcontext_ia32 __user *sc,
 210                                    unsigned int *peax)
 211 {
 212         unsigned int tmpflags, gs, oldgs, err = 0;
 213         struct _fpstate_ia32 __user *buf;
 214         u32 tmp;
 215
 216         /* Always make any pending restarted system calls return -EINTR */
 217         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 218
 219 #if DEBUG_SIG
 220         printk(KERN_DEBUG "SIG restore_sigcontext: "
 221                "sc=%p err(%x) eip(%x) cs(%x) flg(%x)\n",
 222                sc, sc->err, sc->ip, sc->cs, sc->flags);
 223 #endif
 224
 225         /*
 226          * Reload fs and gs if they have changed in the signal
 227          * handler.  This does not handle long fs/gs base changes in
 228          * the handler, but does not clobber them at least in the
 229          * normal case.
 230          */
 231         err |= __get_user(gs, &sc->gs);
 232         gs |= 3;
 233         asm("movl %%gs,%0" : "=r" (oldgs));
 234         if (gs != oldgs)
 235                 load_gs_index(gs);
 236
 237         RELOAD_SEG(fs, 3);
 238         RELOAD_SEG(ds, 3);
 239         RELOAD_SEG(es, 3);
 240
 241         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 242         COPY(dx); COPY(cx); COPY(ip);
 243         /* Don't touch extended registers */
 244
 245         err |= __get_user(regs->cs, &sc->cs);
 246         regs->cs |= 3;
 247         err |= __get_user(regs->ss, &sc->ss);
 248         regs->ss |= 3;
 249
 250         err |= __get_user(tmpflags, &sc->flags);
 251         regs->flags = (regs->flags & ~0x40DD5) | (tmpflags & 0x40DD5);
 252         /* disable syscall checks */
 253         regs->orig_ax = -1;
 254
 255         err |= __get_user(tmp, &sc->fpstate);
 256         buf = compat_ptr(tmp);
 257         if (buf) {
 258                 if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 259                         goto badframe;
 260                 err |= restore_i387_ia32(buf);
 261         } else {
 262                 struct task_struct *me = current;
 263
 264                 if (used_math()) {
 265                         clear_fpu(me);
 266                         clear_used_math();
 267                 }
 268         }
 269
 270         err |= __get_user(tmp, &sc->ax);
 271         *peax = tmp;
 272
 273         return err;
 274
 275 badframe:
 276         return 1;
 277 }
 278
 279 asmlinkage long sys32_sigreturn(struct pt_regs *regs)
 280 {
 281         struct sigframe __user *frame = (struct sigframe __user *)(regs->sp-8);
 282         sigset_t set;
 283         unsigned int ax;
 284
 285         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 286                 goto badframe;
 287         if (__get_user(set.sig[0], &frame->sc.oldmask)
 288             || (_COMPAT_NSIG_WORDS > 1
 289                 && __copy_from_user((((char *) &set.sig) + 4),
 290                                     &frame->extramask,
 291                                     sizeof(frame->extramask))))
 292                 goto badframe;
 293
 294         sigdelsetmask(&set, ~_BLOCKABLE);
 295         spin_lock_irq(&current->sighand->siglock);
 296         current->blocked = set;
 297         recalc_sigpending();
 298         spin_unlock_irq(&current->sighand->siglock);
 299
 300         if (ia32_restore_sigcontext(regs, &frame->sc, &ax))
 301                 goto badframe;
 302         return ax;
 303
 304 badframe:
 305         signal_fault(regs, frame, "32bit sigreturn");
 306         return 0;
 307 }
 308
 309 asmlinkage long sys32_rt_sigreturn(struct pt_regs *regs)
 310 {
 311         struct rt_sigframe __user *frame;
 312         sigset_t set;
 313         unsigned int ax;
 314         struct pt_regs tregs;
 315
 316         frame = (struct rt_sigframe __user *)(regs->sp - 4);
 317
 318         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 319                 goto badframe;
 320         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 321                 goto badframe;
 322
 323         sigdelsetmask(&set, ~_BLOCKABLE);
 324         spin_lock_irq(&current->sighand->siglock);
 325         current->blocked = set;
 326         recalc_sigpending();
 327         spin_unlock_irq(&current->sighand->siglock);
 328
 329         if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 330                 goto badframe;
 331
 332         tregs = *regs;
 333         if (sys32_sigaltstack(&frame->uc.uc_stack, NULL, &tregs) == -EFAULT)
 334                 goto badframe;
 335
 336         return ax;
 337
 338 badframe:
 339         signal_fault(regs, frame, "32bit rt sigreturn");
 340         return 0;
 341 }
 342
 343 /*
 344  * Set up a signal frame.
 345  */
 346
 347 static int ia32_setup_sigcontext(struct sigcontext_ia32 __user *sc,
 348                                  struct _fpstate_ia32 __user *fpstate,
 349                                  struct pt_regs *regs, unsigned int mask)
 350 {
 351         int tmp, err = 0;
 352
 353         tmp = 0;
 354         __asm__("movl %%gs,%0" : "=r"(tmp): "0"(tmp));
 355         err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 356         __asm__("movl %%fs,%0" : "=r"(tmp): "0"(tmp));
 357         err |= __put_user(tmp, (unsigned int __user *)&sc->fs);
 358         __asm__("movl %%ds,%0" : "=r"(tmp): "0"(tmp));
 359         err |= __put_user(tmp, (unsigned int __user *)&sc->ds);
 360         __asm__("movl %%es,%0" : "=r"(tmp): "0"(tmp));
 361         err |= __put_user(tmp, (unsigned int __user *)&sc->es);
 362
 363         err |= __put_user((u32)regs->di, &sc->di);
 364         err |= __put_user((u32)regs->si, &sc->si);
 365         err |= __put_user((u32)regs->bp, &sc->bp);
 366         err |= __put_user((u32)regs->sp, &sc->sp);
 367         err |= __put_user((u32)regs->bx, &sc->bx);
 368         err |= __put_user((u32)regs->dx, &sc->dx);
 369         err |= __put_user((u32)regs->cx, &sc->cx);
 370         err |= __put_user((u32)regs->ax, &sc->ax);
 371         err |= __put_user((u32)regs->cs, &sc->cs);
 372         err |= __put_user((u32)regs->ss, &sc->ss);
 373         err |= __put_user(current->thread.trap_no, &sc->trapno);
 374         err |= __put_user(current->thread.error_code, &sc->err);
 375         err |= __put_user((u32)regs->ip, &sc->ip);
 376         err |= __put_user((u32)regs->flags, &sc->flags);
 377         err |= __put_user((u32)regs->sp, &sc->sp_at_signal);
 378
 379         tmp = save_i387_ia32(fpstate);
 380         if (tmp < 0)
 381                 err = -EFAULT;
 382         else {
 383                 clear_used_math();
 384                 stts();
 385                 err |= __put_user(ptr_to_compat(tmp ? fpstate : NULL),
 386                                         &sc->fpstate);
 387         }
 388
 389         /* non-iBCS2 extensions.. */
 390         err |= __put_user(mask, &sc->oldmask);
 391         err |= __put_user(current->thread.cr2, &sc->cr2);
 392
 393         return err;
 394 }
 395
 396 /*
 397  * Determine which stack to use..
 398  */
 399 static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 400                                  size_t frame_size)
 401 {
 402         unsigned long sp;
 403
 404         /* Default to using normal stack */
 405         sp = regs->sp;
 406
 407         /* This is the X/Open sanctioned signal stack switching.  */
 408         if (ka->sa.sa_flags & SA_ONSTACK) {
 409                 if (sas_ss_flags(sp) == 0)
 410                         sp = current->sas_ss_sp + current->sas_ss_size;
 411         }
 412
 413         /* This is the legacy signal stack switching. */
 414         else if ((regs->ss & 0xffff) != __USER_DS &&
 415                 !(ka->sa.sa_flags & SA_RESTORER) &&
 416                  ka->sa.sa_restorer)
 417                 sp = (unsigned long) ka->sa.sa_restorer;
 418
 419         sp -= frame_size;
 420         /* Align the stack pointer according to the i386 ABI,
 421          * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 422         sp = ((sp + 4) & -16ul) - 4;
 423         return (void __user *) sp;
 424 }
 425
 426 int ia32_setup_frame(int sig, struct k_sigaction *ka,
 427                      compat_sigset_t *set, struct pt_regs *regs)
 428 {
 429         struct sigframe __user *frame;
 430         void __user *restorer;
 431         int err = 0;
 432
 433         /* copy_to_user optimizes that into a single 8 byte store */
 434         static const struct {
 435                 u16 poplmovl;
 436                 u32 val;
 437                 u16 int80;
 438                 u16 pad;
 439         } __attribute__((packed)) code = {
 440                 0xb858,          /* popl %eax ; movl $...,%eax */
 441                 __NR_ia32_sigreturn,
 442                 0x80cd,         /* int $0x80 */
 443                 0,
 444         };
 445
 446         frame = get_sigframe(ka, regs, sizeof(*frame));
 447
 448         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 449                 goto give_sigsegv;
 450
 451         err |= __put_user(sig, &frame->sig);
 452         if (err)
 453                 goto give_sigsegv;
 454
 455         err |= ia32_setup_sigcontext(&frame->sc, &frame->fpstate, regs,
 456                                         set->sig[0]);
 457         if (err)
 458                 goto give_sigsegv;
 459
 460         if (_COMPAT_NSIG_WORDS > 1) {
 461                 err |= __copy_to_user(frame->extramask, &set->sig[1],
 462                                       sizeof(frame->extramask));
 463                 if (err)
 464                         goto give_sigsegv;
 465         }
 466
 467         if (ka->sa.sa_flags & SA_RESTORER) {
 468                 restorer = ka->sa.sa_restorer;
 469         } else {
 470                 /* Return stub is in 32bit vsyscall page */
 471                 if (current->mm->context.vdso)
 472                         restorer = VDSO32_SYMBOL(current->mm->context.vdso,
 473                                                  sigreturn);
 474                 else
 475                         restorer = &frame->retcode;
 476         }
 477         err |= __put_user(ptr_to_compat(restorer), &frame->pretcode);
 478
 479         /*
 480          * These are actually not used anymore, but left because some
 481          * gdb versions depend on them as a marker.
 482          */
 483         err |= __copy_to_user(frame->retcode, &code, 8);
 484         if (err)
 485                 goto give_sigsegv;
 486
 487         /* Set up registers for signal handler */
 488         regs->sp = (unsigned long) frame;
 489         regs->ip = (unsigned long) ka->sa.sa_handler;
 490
 491         /* Make -mregparm=3 work */
 492         regs->ax = sig;
 493         regs->dx = 0;
 494         regs->cx = 0;
 495
 496         asm volatile("movl %0,%%ds" :: "r" (__USER32_DS));
 497         asm volatile("movl %0,%%es" :: "r" (__USER32_DS));
 498
 499         regs->cs = __USER32_CS;
 500         regs->ss = __USER32_DS;
 501
 502 #if DEBUG_SIG
 503         printk(KERN_DEBUG "SIG deliver (%s:%d): sp=%p pc=%lx ra=%u\n",
 504                current->comm, current->pid, frame, regs->ip, frame->pretcode);
 505 #endif
 506
 507         return 0;
 508
 509 give_sigsegv:
 510         force_sigsegv(sig, current);
 511         return -EFAULT;
 512 }
 513
 514 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 515                         compat_sigset_t *set, struct pt_regs *regs)
 516 {
 517         struct rt_sigframe __user *frame;
 518         struct exec_domain *ed = current_thread_info()->exec_domain;
 519         void __user *restorer;
 520         int err = 0;
 521
 522         /* __copy_to_user optimizes that into a single 8 byte store */
 523         static const struct {
 524                 u8 movl;
 525                 u32 val;
 526                 u16 int80;
 527                 u16 pad;
 528                 u8  pad2;
 529         } __attribute__((packed)) code = {
 530                 0xb8,
 531                 __NR_ia32_rt_sigreturn,
 532                 0x80cd,
 533                 0,
 534         };
 535
 536         frame = get_sigframe(ka, regs, sizeof(*frame));
 537
 538         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 539                 goto give_sigsegv;
 540
 541         err |= __put_user((ed && ed->signal_invmap && sig < 32
 542                            ? ed->signal_invmap[sig] : sig), &frame->sig);
 543         err |= __put_user(ptr_to_compat(&frame->info), &frame->pinfo);
 544         err |= __put_user(ptr_to_compat(&frame->uc), &frame->puc);
 545         err |= copy_siginfo_to_user32(&frame->info, info);
 546         if (err)
 547                 goto give_sigsegv;
 548
 549         /* Create the ucontext.  */
 550         err |= __put_user(0, &frame->uc.uc_flags);
 551         err |= __put_user(0, &frame->uc.uc_link);
 552         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 553         err |= __put_user(sas_ss_flags(regs->sp),
 554                           &frame->uc.uc_stack.ss_flags);
 555         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 556         err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
 557                                      regs, set->sig[0]);
 558         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 559         if (err)
 560                 goto give_sigsegv;
 561
 562         if (ka->sa.sa_flags & SA_RESTORER)
 563                 restorer = ka->sa.sa_restorer;
 564         else
 565                 restorer = VDSO32_SYMBOL(current->mm->context.vdso,
 566                                          rt_sigreturn);
 567         err |= __put_user(ptr_to_compat(restorer), &frame->pretcode);
 568
 569         /*
 570          * Not actually used anymore, but left because some gdb
 571          * versions need it.
 572          */
 573         err |= __copy_to_user(frame->retcode, &code, 8);
 574         if (err)
 575                 goto give_sigsegv;
 576
 577         /* Set up registers for signal handler */
 578         regs->sp = (unsigned long) frame;
 579         regs->ip = (unsigned long) ka->sa.sa_handler;
 580
 581         /* Make -mregparm=3 work */
 582         regs->ax = sig;
 583         regs->dx = (unsigned long) &frame->info;
 584         regs->cx = (unsigned long) &frame->uc;
 585
 586         /* Make -mregparm=3 work */
 587         regs->ax = sig;
 588         regs->dx = (unsigned long) &frame->info;
 589         regs->cx = (unsigned long) &frame->uc;
 590
 591         asm volatile("movl %0,%%ds" :: "r" (__USER32_DS));
 592         asm volatile("movl %0,%%es" :: "r" (__USER32_DS));
 593
 594         regs->cs = __USER32_CS;
 595         regs->ss = __USER32_DS;
 596
 597 #if DEBUG_SIG
 598         printk(KERN_DEBUG "SIG deliver (%s:%d): sp=%p pc=%lx ra=%u\n",
 599                current->comm, current->pid, frame, regs->ip, frame->pretcode);
 600 #endif
 601
 602         return 0;
 603
 604 give_sigsegv:
 605         force_sigsegv(sig, current);
 606         return -EFAULT;
 607 }