arch/x86/ia32/ia32_signal.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/arch/x86_64/ia32/ia32_signal.c
   4  *
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  *
   7  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   8  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   9  *  2000-12-*   x86-64 compatibility mode signal handling by Andi Kleen
  10  */
  11
  12 #include <linux/sched.h>
  13 #include <linux/sched/task_stack.h>
  14 #include <linux/mm.h>
  15 #include <linux/smp.h>
  16 #include <linux/kernel.h>
  17 #include <linux/errno.h>
  18 #include <linux/wait.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 <linux/syscalls.h>
  25 #include <asm/ucontext.h>
  26 #include <linux/uaccess.h>
  27 #include <asm/fpu/internal.h>
  28 #include <asm/fpu/signal.h>
  29 #include <asm/ptrace.h>
  30 #include <asm/ia32_unistd.h>
  31 #include <asm/user32.h>
  32 #include <uapi/asm/sigcontext.h>
  33 #include <asm/proto.h>
  34 #include <asm/vdso.h>
  35 #include <asm/sigframe.h>
  36 #include <asm/sighandling.h>
  37 #include <asm/smap.h>
  38
  39 /*
  40  * Do a signal return; undo the signal stack.
  41  */
  42 #define loadsegment_gs(v)       load_gs_index(v)
  43 #define loadsegment_fs(v)       loadsegment(fs, v)
  44 #define loadsegment_ds(v)       loadsegment(ds, v)
  45 #define loadsegment_es(v)       loadsegment(es, v)
  46
  47 #define get_user_seg(seg)       ({ unsigned int v; savesegment(seg, v); v; })
  48 #define set_user_seg(seg, v)    loadsegment_##seg(v)
  49
  50 #define COPY(x)                 {               \
  51         get_user_ex(regs->x, &sc->x);           \
  52 }
  53
  54 #define GET_SEG(seg)            ({                      \
  55         unsigned short tmp;                             \
  56         get_user_ex(tmp, &sc->seg);                     \
  57         tmp;                                            \
  58 })
  59
  60 #define COPY_SEG_CPL3(seg)      do {                    \
  61         regs->seg = GET_SEG(seg) | 3;                   \
  62 } while (0)
  63
  64 #define RELOAD_SEG(seg)         {               \
  65         unsigned int pre = (seg) | 3;           \
  66         unsigned int cur = get_user_seg(seg);   \
  67         if (pre != cur)                         \
  68                 set_user_seg(seg, pre);         \
  69 }
  70
  71 static int ia32_restore_sigcontext(struct pt_regs *regs,
  72                                    struct sigcontext_32 __user *sc)
  73 {
  74         unsigned int tmpflags, err = 0;
  75         u16 gs, fs, es, ds;
  76         void __user *buf;
  77         u32 tmp;
  78
  79         /* Always make any pending restarted system calls return -EINTR */
  80         current->restart_block.fn = do_no_restart_syscall;
  81
  82         get_user_try {
  83                 gs = GET_SEG(gs);
  84                 fs = GET_SEG(fs);
  85                 ds = GET_SEG(ds);
  86                 es = GET_SEG(es);
  87
  88                 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  89                 COPY(dx); COPY(cx); COPY(ip); COPY(ax);
  90                 /* Don't touch extended registers */
  91
  92                 COPY_SEG_CPL3(cs);
  93                 COPY_SEG_CPL3(ss);
  94
  95                 get_user_ex(tmpflags, &sc->flags);
  96                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
  97                 /* disable syscall checks */
  98                 regs->orig_ax = -1;
  99
 100                 get_user_ex(tmp, &sc->fpstate);
 101                 buf = compat_ptr(tmp);
 102         } get_user_catch(err);
 103
 104         /*
 105          * Reload fs and gs if they have changed in the signal
 106          * handler.  This does not handle long fs/gs base changes in
 107          * the handler, but does not clobber them at least in the
 108          * normal case.
 109          */
 110         RELOAD_SEG(gs);
 111         RELOAD_SEG(fs);
 112         RELOAD_SEG(ds);
 113         RELOAD_SEG(es);
 114
 115         err |= fpu__restore_sig(buf, 1);
 116
 117         return err;
 118 }
 119
 120 COMPAT_SYSCALL_DEFINE0(sigreturn)
 121 {
 122         struct pt_regs *regs = current_pt_regs();
 123         struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
 124         sigset_t set;
 125
 126         if (!access_ok(frame, sizeof(*frame)))
 127                 goto badframe;
 128         if (__get_user(set.sig[0], &frame->sc.oldmask)
 129             || (_COMPAT_NSIG_WORDS > 1
 130                 && __copy_from_user((((char *) &set.sig) + 4),
 131                                     &frame->extramask,
 132                                     sizeof(frame->extramask))))
 133                 goto badframe;
 134
 135         set_current_blocked(&set);
 136
 137         if (ia32_restore_sigcontext(regs, &frame->sc))
 138                 goto badframe;
 139         return regs->ax;
 140
 141 badframe:
 142         signal_fault(regs, frame, "32bit sigreturn");
 143         return 0;
 144 }
 145
 146 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
 147 {
 148         struct pt_regs *regs = current_pt_regs();
 149         struct rt_sigframe_ia32 __user *frame;
 150         sigset_t set;
 151
 152         frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
 153
 154         if (!access_ok(frame, sizeof(*frame)))
 155                 goto badframe;
 156         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 157                 goto badframe;
 158
 159         set_current_blocked(&set);
 160
 161         if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
 162                 goto badframe;
 163
 164         if (compat_restore_altstack(&frame->uc.uc_stack))
 165                 goto badframe;
 166
 167         return regs->ax;
 168
 169 badframe:
 170         signal_fault(regs, frame, "32bit rt sigreturn");
 171         return 0;
 172 }
 173
 174 /*
 175  * Set up a signal frame.
 176  */
 177
 178 static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
 179                                  void __user *fpstate,
 180                                  struct pt_regs *regs, unsigned int mask)
 181 {
 182         int err = 0;
 183
 184         put_user_try {
 185                 put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
 186                 put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
 187                 put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
 188                 put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);
 189
 190                 put_user_ex(regs->di, &sc->di);
 191                 put_user_ex(regs->si, &sc->si);
 192                 put_user_ex(regs->bp, &sc->bp);
 193                 put_user_ex(regs->sp, &sc->sp);
 194                 put_user_ex(regs->bx, &sc->bx);
 195                 put_user_ex(regs->dx, &sc->dx);
 196                 put_user_ex(regs->cx, &sc->cx);
 197                 put_user_ex(regs->ax, &sc->ax);
 198                 put_user_ex(current->thread.trap_nr, &sc->trapno);
 199                 put_user_ex(current->thread.error_code, &sc->err);
 200                 put_user_ex(regs->ip, &sc->ip);
 201                 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 202                 put_user_ex(regs->flags, &sc->flags);
 203                 put_user_ex(regs->sp, &sc->sp_at_signal);
 204                 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 205
 206                 put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
 207
 208                 /* non-iBCS2 extensions.. */
 209                 put_user_ex(mask, &sc->oldmask);
 210                 put_user_ex(current->thread.cr2, &sc->cr2);
 211         } put_user_catch(err);
 212
 213         return err;
 214 }
 215
 216 /*
 217  * Determine which stack to use..
 218  */
 219 static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
 220                                  size_t frame_size,
 221                                  void __user **fpstate)
 222 {
 223         unsigned long sp, fx_aligned, math_size;
 224
 225         /* Default to using normal stack */
 226         sp = regs->sp;
 227
 228         /* This is the X/Open sanctioned signal stack switching.  */
 229         if (ksig->ka.sa.sa_flags & SA_ONSTACK)
 230                 sp = sigsp(sp, ksig);
 231         /* This is the legacy signal stack switching. */
 232         else if (regs->ss != __USER32_DS &&
 233                 !(ksig->ka.sa.sa_flags & SA_RESTORER) &&
 234                  ksig->ka.sa.sa_restorer)
 235                 sp = (unsigned long) ksig->ka.sa.sa_restorer;
 236
 237         sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
 238         *fpstate = (struct _fpstate_32 __user *) sp;
 239         if (copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
 240                                      math_size) < 0)
 241                 return (void __user *) -1L;
 242
 243         sp -= frame_size;
 244         /* Align the stack pointer according to the i386 ABI,
 245          * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 246         sp = ((sp + 4) & -16ul) - 4;
 247         return (void __user *) sp;
 248 }
 249
 250 int ia32_setup_frame(int sig, struct ksignal *ksig,
 251                      compat_sigset_t *set, struct pt_regs *regs)
 252 {
 253         struct sigframe_ia32 __user *frame;
 254         void __user *restorer;
 255         int err = 0;
 256         void __user *fpstate = NULL;
 257
 258         /* copy_to_user optimizes that into a single 8 byte store */
 259         static const struct {
 260                 u16 poplmovl;
 261                 u32 val;
 262                 u16 int80;
 263         } __attribute__((packed)) code = {
 264                 0xb858,          /* popl %eax ; movl $...,%eax */
 265                 __NR_ia32_sigreturn,
 266                 0x80cd,         /* int $0x80 */
 267         };
 268
 269         frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
 270
 271         if (!access_ok(frame, sizeof(*frame)))
 272                 return -EFAULT;
 273
 274         if (__put_user(sig, &frame->sig))
 275                 return -EFAULT;
 276
 277         if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 278                 return -EFAULT;
 279
 280         if (_COMPAT_NSIG_WORDS > 1) {
 281                 if (__copy_to_user(frame->extramask, &set->sig[1],
 282                                    sizeof(frame->extramask)))
 283                         return -EFAULT;
 284         }
 285
 286         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 287                 restorer = ksig->ka.sa.sa_restorer;
 288         } else {
 289                 /* Return stub is in 32bit vsyscall page */
 290                 if (current->mm->context.vdso)
 291                         restorer = current->mm->context.vdso +
 292                                 vdso_image_32.sym___kernel_sigreturn;
 293                 else
 294                         restorer = &frame->retcode;
 295         }
 296
 297         put_user_try {
 298                 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 299
 300                 /*
 301                  * These are actually not used anymore, but left because some
 302                  * gdb versions depend on them as a marker.
 303                  */
 304                 put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
 305         } put_user_catch(err);
 306
 307         if (err)
 308                 return -EFAULT;
 309
 310         /* Set up registers for signal handler */
 311         regs->sp = (unsigned long) frame;
 312         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 313
 314         /* Make -mregparm=3 work */
 315         regs->ax = sig;
 316         regs->dx = 0;
 317         regs->cx = 0;
 318
 319         loadsegment(ds, __USER32_DS);
 320         loadsegment(es, __USER32_DS);
 321
 322         regs->cs = __USER32_CS;
 323         regs->ss = __USER32_DS;
 324
 325         return 0;
 326 }
 327
 328 int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
 329                         compat_sigset_t *set, struct pt_regs *regs)
 330 {
 331         struct rt_sigframe_ia32 __user *frame;
 332         void __user *restorer;
 333         int err = 0;
 334         void __user *fpstate = NULL;
 335
 336         /* __copy_to_user optimizes that into a single 8 byte store */
 337         static const struct {
 338                 u8 movl;
 339                 u32 val;
 340                 u16 int80;
 341                 u8  pad;
 342         } __attribute__((packed)) code = {
 343                 0xb8,
 344                 __NR_ia32_rt_sigreturn,
 345                 0x80cd,
 346                 0,
 347         };
 348
 349         frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
 350
 351         if (!access_ok(frame, sizeof(*frame)))
 352                 return -EFAULT;
 353
 354         put_user_try {
 355                 put_user_ex(sig, &frame->sig);
 356                 put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
 357                 put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
 358
 359                 /* Create the ucontext.  */
 360                 if (static_cpu_has(X86_FEATURE_XSAVE))
 361                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 362                 else
 363                         put_user_ex(0, &frame->uc.uc_flags);
 364                 put_user_ex(0, &frame->uc.uc_link);
 365                 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 366
 367                 if (ksig->ka.sa.sa_flags & SA_RESTORER)
 368                         restorer = ksig->ka.sa.sa_restorer;
 369                 else
 370                         restorer = current->mm->context.vdso +
 371                                 vdso_image_32.sym___kernel_rt_sigreturn;
 372                 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 373
 374                 /*
 375                  * Not actually used anymore, but left because some gdb
 376                  * versions need it.
 377                  */
 378                 put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
 379         } put_user_catch(err);
 380
 381         err |= __copy_siginfo_to_user32(&frame->info, &ksig->info, false);
 382         err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 383                                      regs, set->sig[0]);
 384         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 385
 386         if (err)
 387                 return -EFAULT;
 388
 389         /* Set up registers for signal handler */
 390         regs->sp = (unsigned long) frame;
 391         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 392
 393         /* Make -mregparm=3 work */
 394         regs->ax = sig;
 395         regs->dx = (unsigned long) &frame->info;
 396         regs->cx = (unsigned long) &frame->uc;
 397
 398         loadsegment(ds, __USER32_DS);
 399         loadsegment(es, __USER32_DS);
 400
 401         regs->cs = __USER32_CS;
 402         regs->ss = __USER32_DS;
 403
 404         return 0;
 405 }