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
ia32_restore_sigcontext(struct pt_regs * regs,struct sigcontext_32 __user * sc)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 force_iret();
118
119 return err;
120 }
121
COMPAT_SYSCALL_DEFINE0(sigreturn)122 COMPAT_SYSCALL_DEFINE0(sigreturn)
123 {
124 struct pt_regs *regs = current_pt_regs();
125 struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
126 sigset_t set;
127
128 if (!access_ok(frame, sizeof(*frame)))
129 goto badframe;
130 if (__get_user(set.sig[0], &frame->sc.oldmask)
131 || (_COMPAT_NSIG_WORDS > 1
132 && __copy_from_user((((char *) &set.sig) + 4),
133 &frame->extramask,
134 sizeof(frame->extramask))))
135 goto badframe;
136
137 set_current_blocked(&set);
138
139 if (ia32_restore_sigcontext(regs, &frame->sc))
140 goto badframe;
141 return regs->ax;
142
143 badframe:
144 signal_fault(regs, frame, "32bit sigreturn");
145 return 0;
146 }
147
COMPAT_SYSCALL_DEFINE0(rt_sigreturn)148 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
149 {
150 struct pt_regs *regs = current_pt_regs();
151 struct rt_sigframe_ia32 __user *frame;
152 sigset_t set;
153
154 frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
155
156 if (!access_ok(frame, sizeof(*frame)))
157 goto badframe;
158 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
159 goto badframe;
160
161 set_current_blocked(&set);
162
163 if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
164 goto badframe;
165
166 if (compat_restore_altstack(&frame->uc.uc_stack))
167 goto badframe;
168
169 return regs->ax;
170
171 badframe:
172 signal_fault(regs, frame, "32bit rt sigreturn");
173 return 0;
174 }
175
176 /*
177 * Set up a signal frame.
178 */
179
ia32_setup_sigcontext(struct sigcontext_32 __user * sc,void __user * fpstate,struct pt_regs * regs,unsigned int mask)180 static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
181 void __user *fpstate,
182 struct pt_regs *regs, unsigned int mask)
183 {
184 int err = 0;
185
186 put_user_try {
187 put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
188 put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
189 put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
190 put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);
191
192 put_user_ex(regs->di, &sc->di);
193 put_user_ex(regs->si, &sc->si);
194 put_user_ex(regs->bp, &sc->bp);
195 put_user_ex(regs->sp, &sc->sp);
196 put_user_ex(regs->bx, &sc->bx);
197 put_user_ex(regs->dx, &sc->dx);
198 put_user_ex(regs->cx, &sc->cx);
199 put_user_ex(regs->ax, &sc->ax);
200 put_user_ex(current->thread.trap_nr, &sc->trapno);
201 put_user_ex(current->thread.error_code, &sc->err);
202 put_user_ex(regs->ip, &sc->ip);
203 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
204 put_user_ex(regs->flags, &sc->flags);
205 put_user_ex(regs->sp, &sc->sp_at_signal);
206 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
207
208 put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
209
210 /* non-iBCS2 extensions.. */
211 put_user_ex(mask, &sc->oldmask);
212 put_user_ex(current->thread.cr2, &sc->cr2);
213 } put_user_catch(err);
214
215 return err;
216 }
217
218 /*
219 * Determine which stack to use..
220 */
get_sigframe(struct ksignal * ksig,struct pt_regs * regs,size_t frame_size,void __user ** fpstate)221 static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
222 size_t frame_size,
223 void __user **fpstate)
224 {
225 unsigned long sp, fx_aligned, math_size;
226
227 /* Default to using normal stack */
228 sp = regs->sp;
229
230 /* This is the X/Open sanctioned signal stack switching. */
231 if (ksig->ka.sa.sa_flags & SA_ONSTACK)
232 sp = sigsp(sp, ksig);
233 /* This is the legacy signal stack switching. */
234 else if (regs->ss != __USER32_DS &&
235 !(ksig->ka.sa.sa_flags & SA_RESTORER) &&
236 ksig->ka.sa.sa_restorer)
237 sp = (unsigned long) ksig->ka.sa.sa_restorer;
238
239 sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
240 *fpstate = (struct _fpstate_32 __user *) sp;
241 if (copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
242 math_size) < 0)
243 return (void __user *) -1L;
244
245 sp -= frame_size;
246 /* Align the stack pointer according to the i386 ABI,
247 * i.e. so that on function entry ((sp + 4) & 15) == 0. */
248 sp = ((sp + 4) & -16ul) - 4;
249 return (void __user *) sp;
250 }
251
ia32_setup_frame(int sig,struct ksignal * ksig,compat_sigset_t * set,struct pt_regs * regs)252 int ia32_setup_frame(int sig, struct ksignal *ksig,
253 compat_sigset_t *set, struct pt_regs *regs)
254 {
255 struct sigframe_ia32 __user *frame;
256 void __user *restorer;
257 int err = 0;
258 void __user *fpstate = NULL;
259
260 /* copy_to_user optimizes that into a single 8 byte store */
261 static const struct {
262 u16 poplmovl;
263 u32 val;
264 u16 int80;
265 } __attribute__((packed)) code = {
266 0xb858, /* popl %eax ; movl $...,%eax */
267 __NR_ia32_sigreturn,
268 0x80cd, /* int $0x80 */
269 };
270
271 frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
272
273 if (!access_ok(frame, sizeof(*frame)))
274 return -EFAULT;
275
276 if (__put_user(sig, &frame->sig))
277 return -EFAULT;
278
279 if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
280 return -EFAULT;
281
282 if (_COMPAT_NSIG_WORDS > 1) {
283 if (__copy_to_user(frame->extramask, &set->sig[1],
284 sizeof(frame->extramask)))
285 return -EFAULT;
286 }
287
288 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
289 restorer = ksig->ka.sa.sa_restorer;
290 } else {
291 /* Return stub is in 32bit vsyscall page */
292 if (current->mm->context.vdso)
293 restorer = current->mm->context.vdso +
294 vdso_image_32.sym___kernel_sigreturn;
295 else
296 restorer = &frame->retcode;
297 }
298
299 put_user_try {
300 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
301
302 /*
303 * These are actually not used anymore, but left because some
304 * gdb versions depend on them as a marker.
305 */
306 put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
307 } put_user_catch(err);
308
309 if (err)
310 return -EFAULT;
311
312 /* Set up registers for signal handler */
313 regs->sp = (unsigned long) frame;
314 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
315
316 /* Make -mregparm=3 work */
317 regs->ax = sig;
318 regs->dx = 0;
319 regs->cx = 0;
320
321 loadsegment(ds, __USER32_DS);
322 loadsegment(es, __USER32_DS);
323
324 regs->cs = __USER32_CS;
325 regs->ss = __USER32_DS;
326
327 return 0;
328 }
329
ia32_setup_rt_frame(int sig,struct ksignal * ksig,compat_sigset_t * set,struct pt_regs * regs)330 int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
331 compat_sigset_t *set, struct pt_regs *regs)
332 {
333 struct rt_sigframe_ia32 __user *frame;
334 void __user *restorer;
335 int err = 0;
336 void __user *fpstate = NULL;
337
338 /* __copy_to_user optimizes that into a single 8 byte store */
339 static const struct {
340 u8 movl;
341 u32 val;
342 u16 int80;
343 u8 pad;
344 } __attribute__((packed)) code = {
345 0xb8,
346 __NR_ia32_rt_sigreturn,
347 0x80cd,
348 0,
349 };
350
351 frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
352
353 if (!access_ok(frame, sizeof(*frame)))
354 return -EFAULT;
355
356 put_user_try {
357 put_user_ex(sig, &frame->sig);
358 put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
359 put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
360
361 /* Create the ucontext. */
362 if (static_cpu_has(X86_FEATURE_XSAVE))
363 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
364 else
365 put_user_ex(0, &frame->uc.uc_flags);
366 put_user_ex(0, &frame->uc.uc_link);
367 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
368
369 if (ksig->ka.sa.sa_flags & SA_RESTORER)
370 restorer = ksig->ka.sa.sa_restorer;
371 else
372 restorer = current->mm->context.vdso +
373 vdso_image_32.sym___kernel_rt_sigreturn;
374 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
375
376 /*
377 * Not actually used anymore, but left because some gdb
378 * versions need it.
379 */
380 put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
381 } put_user_catch(err);
382
383 err |= __copy_siginfo_to_user32(&frame->info, &ksig->info, false);
384 err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
385 regs, set->sig[0]);
386 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
387
388 if (err)
389 return -EFAULT;
390
391 /* Set up registers for signal handler */
392 regs->sp = (unsigned long) frame;
393 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
394
395 /* Make -mregparm=3 work */
396 regs->ax = sig;
397 regs->dx = (unsigned long) &frame->info;
398 regs->cx = (unsigned long) &frame->uc;
399
400 loadsegment(ds, __USER32_DS);
401 loadsegment(es, __USER32_DS);
402
403 regs->cs = __USER32_CS;
404 regs->ss = __USER32_DS;
405
406 return 0;
407 }
408