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 <asm/ucontext.h>
  25 #include <linux/uaccess.h>
  26 #include <asm/fpu/internal.h>
  27 #include <asm/fpu/signal.h>
  28 #include <asm/ptrace.h>
  29 #include <asm/ia32_unistd.h>
  30 #include <asm/user32.h>
  31 #include <uapi/asm/sigcontext.h>
  32 #include <asm/proto.h>
  33 #include <asm/vdso.h>
  34 #include <asm/sigframe.h>
  35 #include <asm/sighandling.h>
  36 #include <asm/smap.h>
  37
  38 /*
  39  * Do a signal return; undo the signal stack.
  40  */
  41 #define loadsegment_gs(v)       load_gs_index(v)
  42 #define loadsegment_fs(v)       loadsegment(fs, v)
  43 #define loadsegment_ds(v)       loadsegment(ds, v)
  44 #define loadsegment_es(v)       loadsegment(es, v)
  45
  46 #define get_user_seg(seg)       ({ unsigned int v; savesegment(seg, v); v; })
  47 #define set_user_seg(seg, v)    loadsegment_##seg(v)
  48
  49 #define COPY(x)                 {               \
  50         get_user_ex(regs->x, &sc->x);           \
  51 }
  52
  53 #define GET_SEG(seg)            ({                      \
  54         unsigned short tmp;                             \
  55         get_user_ex(tmp, &sc->seg);                     \
  56         tmp;                                            \
  57 })
  58
  59 #define COPY_SEG_CPL3(seg)      do {                    \
  60         regs->seg = GET_SEG(seg) | 3;                   \
  61 } while (0)
  62
  63 #define RELOAD_SEG(seg)         {               \
  64         unsigned int pre = (seg) | 3;           \
  65         unsigned int cur = get_user_seg(seg);   \
  66         if (pre != cur)                         \
  67                 set_user_seg(seg, pre);         \
  68 }
  69
  70 static int ia32_restore_sigcontext(struct pt_regs *regs,
  71                                    struct sigcontext_32 __user *sc)
  72 {
  73         unsigned int tmpflags, err = 0;
  74         u16 gs, fs, es, ds;
  75         void __user *buf;
  76         u32 tmp;
  77
  78         /* Always make any pending restarted system calls return -EINTR */
  79         current->restart_block.fn = do_no_restart_syscall;
  80
  81         get_user_try {
  82                 gs = GET_SEG(gs);
  83                 fs = GET_SEG(fs);
  84                 ds = GET_SEG(ds);
  85                 es = GET_SEG(es);
  86
  87                 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  88                 COPY(dx); COPY(cx); COPY(ip); COPY(ax);
  89                 /* Don't touch extended registers */
  90
  91                 COPY_SEG_CPL3(cs);
  92                 COPY_SEG_CPL3(ss);
  93
  94                 get_user_ex(tmpflags, &sc->flags);
  95                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
  96                 /* disable syscall checks */
  97                 regs->orig_ax = -1;
  98
  99                 get_user_ex(tmp, &sc->fpstate);
 100                 buf = compat_ptr(tmp);
 101         } get_user_catch(err);
 102
 103         /*
 104          * Reload fs and gs if they have changed in the signal
 105          * handler.  This does not handle long fs/gs base changes in
 106          * the handler, but does not clobber them at least in the
 107          * normal case.
 108          */
 109         RELOAD_SEG(gs);
 110         RELOAD_SEG(fs);
 111         RELOAD_SEG(ds);
 112         RELOAD_SEG(es);
 113
 114         err |= fpu__restore_sig(buf, 1);
 115
 116         force_iret();
 117
 118         return err;
 119 }
 120
 121 asmlinkage long sys32_sigreturn(void)
 122 {
 123         struct pt_regs *regs = current_pt_regs();
 124         struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
 125         sigset_t set;
 126
 127         if (!access_ok(frame, sizeof(*frame)))
 128                 goto badframe;
 129         if (__get_user(set.sig[0], &frame->sc.oldmask)
 130             || (_COMPAT_NSIG_WORDS > 1
 131                 && __copy_from_user((((char *) &set.sig) + 4),
 132                                     &frame->extramask,
 133                                     sizeof(frame->extramask))))
 134                 goto badframe;
 135
 136         set_current_blocked(&set);
 137
 138         if (ia32_restore_sigcontext(regs, &frame->sc))
 139                 goto badframe;
 140         return regs->ax;
 141
 142 badframe:
 143         signal_fault(regs, frame, "32bit sigreturn");
 144         return 0;
 145 }
 146
 147 asmlinkage long sys32_rt_sigreturn(void)
 148 {
 149         struct pt_regs *regs = current_pt_regs();
 150         struct rt_sigframe_ia32 __user *frame;
 151         sigset_t set;
 152
 153         frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
 154
 155         if (!access_ok(frame, sizeof(*frame)))
 156                 goto badframe;
 157         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 158                 goto badframe;
 159
 160         set_current_blocked(&set);
 161
 162         if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
 163                 goto badframe;
 164
 165         if (compat_restore_altstack(&frame->uc.uc_stack))
 166                 goto badframe;
 167
 168         return regs->ax;
 169
 170 badframe:
 171         signal_fault(regs, frame, "32bit rt sigreturn");
 172         return 0;
 173 }
 174
 175 /*
 176  * Set up a signal frame.
 177  */
 178
 179 static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
 180                                  void __user *fpstate,
 181                                  struct pt_regs *regs, unsigned int mask)
 182 {
 183         int err = 0;
 184
 185         put_user_try {
 186                 put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
 187                 put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
 188                 put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
 189                 put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);
 190
 191                 put_user_ex(regs->di, &sc->di);
 192                 put_user_ex(regs->si, &sc->si);
 193                 put_user_ex(regs->bp, &sc->bp);
 194                 put_user_ex(regs->sp, &sc->sp);
 195                 put_user_ex(regs->bx, &sc->bx);
 196                 put_user_ex(regs->dx, &sc->dx);
 197                 put_user_ex(regs->cx, &sc->cx);
 198                 put_user_ex(regs->ax, &sc->ax);
 199                 put_user_ex(current->thread.trap_nr, &sc->trapno);
 200                 put_user_ex(current->thread.error_code, &sc->err);
 201                 put_user_ex(regs->ip, &sc->ip);
 202                 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 203                 put_user_ex(regs->flags, &sc->flags);
 204                 put_user_ex(regs->sp, &sc->sp_at_signal);
 205                 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 206
 207                 put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
 208
 209                 /* non-iBCS2 extensions.. */
 210                 put_user_ex(mask, &sc->oldmask);
 211                 put_user_ex(current->thread.cr2, &sc->cr2);
 212         } put_user_catch(err);
 213
 214         return err;
 215 }
 216
 217 /*
 218  * Determine which stack to use..
 219  */
 220 static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
 221                                  size_t frame_size,
 222                                  void __user **fpstate)
 223 {
 224         unsigned long sp, fx_aligned, math_size;
 225
 226         /* Default to using normal stack */
 227         sp = regs->sp;
 228
 229         /* This is the X/Open sanctioned signal stack switching.  */
 230         if (ksig->ka.sa.sa_flags & SA_ONSTACK)
 231                 sp = sigsp(sp, ksig);
 232         /* This is the legacy signal stack switching. */
 233         else if (regs->ss != __USER32_DS &&
 234                 !(ksig->ka.sa.sa_flags & SA_RESTORER) &&
 235                  ksig->ka.sa.sa_restorer)
 236                 sp = (unsigned long) ksig->ka.sa.sa_restorer;
 237
 238         sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
 239         *fpstate = (struct _fpstate_32 __user *) sp;
 240         if (copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
 241                                      math_size) < 0)
 242                 return (void __user *) -1L;
 243
 244         sp -= frame_size;
 245         /* Align the stack pointer according to the i386 ABI,
 246          * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 247         sp = ((sp + 4) & -16ul) - 4;
 248         return (void __user *) sp;
 249 }
 250
 251 int ia32_setup_frame(int sig, struct ksignal *ksig,
 252                      compat_sigset_t *set, struct pt_regs *regs)
 253 {
 254         struct sigframe_ia32 __user *frame;
 255         void __user *restorer;
 256         int err = 0;
 257         void __user *fpstate = NULL;
 258
 259         /* copy_to_user optimizes that into a single 8 byte store */
 260         static const struct {
 261                 u16 poplmovl;
 262                 u32 val;
 263                 u16 int80;
 264         } __attribute__((packed)) code = {
 265                 0xb858,          /* popl %eax ; movl $...,%eax */
 266                 __NR_ia32_sigreturn,
 267                 0x80cd,         /* int $0x80 */
 268         };
 269
 270         frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
 271
 272         if (!access_ok(frame, sizeof(*frame)))
 273                 return -EFAULT;
 274
 275         if (__put_user(sig, &frame->sig))
 276                 return -EFAULT;
 277
 278         if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 279                 return -EFAULT;
 280
 281         if (_COMPAT_NSIG_WORDS > 1) {
 282                 if (__copy_to_user(frame->extramask, &set->sig[1],
 283                                    sizeof(frame->extramask)))
 284                         return -EFAULT;
 285         }
 286
 287         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 288                 restorer = ksig->ka.sa.sa_restorer;
 289         } else {
 290                 /* Return stub is in 32bit vsyscall page */
 291                 if (current->mm->context.vdso)
 292                         restorer = current->mm->context.vdso +
 293                                 vdso_image_32.sym___kernel_sigreturn;
 294                 else
 295                         restorer = &frame->retcode;
 296         }
 297
 298         put_user_try {
 299                 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 300
 301                 /*
 302                  * These are actually not used anymore, but left because some
 303                  * gdb versions depend on them as a marker.
 304                  */
 305                 put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
 306         } put_user_catch(err);
 307
 308         if (err)
 309                 return -EFAULT;
 310
 311         /* Set up registers for signal handler */
 312         regs->sp = (unsigned long) frame;
 313         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 314
 315         /* Make -mregparm=3 work */
 316         regs->ax = sig;
 317         regs->dx = 0;
 318         regs->cx = 0;
 319
 320         loadsegment(ds, __USER32_DS);
 321         loadsegment(es, __USER32_DS);
 322
 323         regs->cs = __USER32_CS;
 324         regs->ss = __USER32_DS;
 325
 326         return 0;
 327 }
 328
 329 int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
 330                         compat_sigset_t *set, struct pt_regs *regs)
 331 {
 332         struct rt_sigframe_ia32 __user *frame;
 333         void __user *restorer;
 334         int err = 0;
 335         void __user *fpstate = NULL;
 336
 337         /* __copy_to_user optimizes that into a single 8 byte store */
 338         static const struct {
 339                 u8 movl;
 340                 u32 val;
 341                 u16 int80;
 342                 u8  pad;
 343         } __attribute__((packed)) code = {
 344                 0xb8,
 345                 __NR_ia32_rt_sigreturn,
 346                 0x80cd,
 347                 0,
 348         };
 349
 350         frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
 351
 352         if (!access_ok(frame, sizeof(*frame)))
 353                 return -EFAULT;
 354
 355         put_user_try {
 356                 put_user_ex(sig, &frame->sig);
 357                 put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
 358                 put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
 359
 360                 /* Create the ucontext.  */
 361                 if (static_cpu_has(X86_FEATURE_XSAVE))
 362                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 363                 else
 364                         put_user_ex(0, &frame->uc.uc_flags);
 365                 put_user_ex(0, &frame->uc.uc_link);
 366                 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 367
 368                 if (ksig->ka.sa.sa_flags & SA_RESTORER)
 369                         restorer = ksig->ka.sa.sa_restorer;
 370                 else
 371                         restorer = current->mm->context.vdso +
 372                                 vdso_image_32.sym___kernel_rt_sigreturn;
 373                 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 374
 375                 /*
 376                  * Not actually used anymore, but left because some gdb
 377                  * versions need it.
 378                  */
 379                 put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
 380         } put_user_catch(err);
 381
 382         err |= __copy_siginfo_to_user32(&frame->info, &ksig->info, false);
 383         err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 384                                      regs, set->sig[0]);
 385         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 386
 387         if (err)
 388                 return -EFAULT;
 389
 390         /* Set up registers for signal handler */
 391         regs->sp = (unsigned long) frame;
 392         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 393
 394         /* Make -mregparm=3 work */
 395         regs->ax = sig;
 396         regs->dx = (unsigned long) &frame->info;
 397         regs->cx = (unsigned long) &frame->uc;
 398
 399         loadsegment(ds, __USER32_DS);
 400         loadsegment(es, __USER32_DS);
 401
 402         regs->cs = __USER32_CS;
 403         regs->ss = __USER32_DS;
 404
 405         return 0;
 406 }