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Linux/arch/x86/ia32/ia32_signal.c

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  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 = GET_SEG(seg);        \
 65         unsigned int cur = get_user_seg(seg);   \
 66         pre |= 3;                               \
 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         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                 /*
 83                  * Reload fs and gs if they have changed in the signal
 84                  * handler.  This does not handle long fs/gs base changes in
 85                  * the handler, but does not clobber them at least in the
 86                  * normal case.
 87                  */
 88                 RELOAD_SEG(gs);
 89                 RELOAD_SEG(fs);
 90                 RELOAD_SEG(ds);
 91                 RELOAD_SEG(es);
 92 
 93                 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 94                 COPY(dx); COPY(cx); COPY(ip); COPY(ax);
 95                 /* Don't touch extended registers */
 96 
 97                 COPY_SEG_CPL3(cs);
 98                 COPY_SEG_CPL3(ss);
 99 
100                 get_user_ex(tmpflags, &sc->flags);
101                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
102                 /* disable syscall checks */
103                 regs->orig_ax = -1;
104 
105                 get_user_ex(tmp, &sc->fpstate);
106                 buf = compat_ptr(tmp);
107         } get_user_catch(err);
108 
109         err |= fpu__restore_sig(buf, 1);
110 
111         force_iret();
112 
113         return err;
114 }
115 
116 asmlinkage long sys32_sigreturn(void)
117 {
118         struct pt_regs *regs = current_pt_regs();
119         struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
120         sigset_t set;
121 
122         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
123                 goto badframe;
124         if (__get_user(set.sig[0], &frame->sc.oldmask)
125             || (_COMPAT_NSIG_WORDS > 1
126                 && __copy_from_user((((char *) &set.sig) + 4),
127                                     &frame->extramask,
128                                     sizeof(frame->extramask))))
129                 goto badframe;
130 
131         set_current_blocked(&set);
132 
133         if (ia32_restore_sigcontext(regs, &frame->sc))
134                 goto badframe;
135         return regs->ax;
136 
137 badframe:
138         signal_fault(regs, frame, "32bit sigreturn");
139         return 0;
140 }
141 
142 asmlinkage long sys32_rt_sigreturn(void)
143 {
144         struct pt_regs *regs = current_pt_regs();
145         struct rt_sigframe_ia32 __user *frame;
146         sigset_t set;
147 
148         frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
149 
150         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
151                 goto badframe;
152         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
153                 goto badframe;
154 
155         set_current_blocked(&set);
156 
157         if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
158                 goto badframe;
159 
160         if (compat_restore_altstack(&frame->uc.uc_stack))
161                 goto badframe;
162 
163         return regs->ax;
164 
165 badframe:
166         signal_fault(regs, frame, "32bit rt sigreturn");
167         return 0;
168 }
169 
170 /*
171  * Set up a signal frame.
172  */
173 
174 static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
175                                  void __user *fpstate,
176                                  struct pt_regs *regs, unsigned int mask)
177 {
178         int err = 0;
179 
180         put_user_try {
181                 put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
182                 put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
183                 put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
184                 put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);
185 
186                 put_user_ex(regs->di, &sc->di);
187                 put_user_ex(regs->si, &sc->si);
188                 put_user_ex(regs->bp, &sc->bp);
189                 put_user_ex(regs->sp, &sc->sp);
190                 put_user_ex(regs->bx, &sc->bx);
191                 put_user_ex(regs->dx, &sc->dx);
192                 put_user_ex(regs->cx, &sc->cx);
193                 put_user_ex(regs->ax, &sc->ax);
194                 put_user_ex(current->thread.trap_nr, &sc->trapno);
195                 put_user_ex(current->thread.error_code, &sc->err);
196                 put_user_ex(regs->ip, &sc->ip);
197                 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
198                 put_user_ex(regs->flags, &sc->flags);
199                 put_user_ex(regs->sp, &sc->sp_at_signal);
200                 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
201 
202                 put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
203 
204                 /* non-iBCS2 extensions.. */
205                 put_user_ex(mask, &sc->oldmask);
206                 put_user_ex(current->thread.cr2, &sc->cr2);
207         } put_user_catch(err);
208 
209         return err;
210 }
211 
212 /*
213  * Determine which stack to use..
214  */
215 static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
216                                  size_t frame_size,
217                                  void __user **fpstate)
218 {
219         struct fpu *fpu = &current->thread.fpu;
220         unsigned long sp;
221 
222         /* Default to using normal stack */
223         sp = regs->sp;
224 
225         /* This is the X/Open sanctioned signal stack switching.  */
226         if (ksig->ka.sa.sa_flags & SA_ONSTACK)
227                 sp = sigsp(sp, ksig);
228         /* This is the legacy signal stack switching. */
229         else if (regs->ss != __USER32_DS &&
230                 !(ksig->ka.sa.sa_flags & SA_RESTORER) &&
231                  ksig->ka.sa.sa_restorer)
232                 sp = (unsigned long) ksig->ka.sa.sa_restorer;
233 
234         if (fpu->initialized) {
235                 unsigned long fx_aligned, math_size;
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 
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(VERIFY_WRITE, 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(VERIFY_WRITE, 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 (boot_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 }
407 

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