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
reload_segments(struct sigcontext_32 * sc)39 static inline void reload_segments(struct sigcontext_32 *sc)
40 {
41 unsigned int cur;
42
43 savesegment(gs, cur);
44 if ((sc->gs | 0x03) != cur)
45 load_gs_index(sc->gs | 0x03);
46 savesegment(fs, cur);
47 if ((sc->fs | 0x03) != cur)
48 loadsegment(fs, sc->fs | 0x03);
49 savesegment(ds, cur);
50 if ((sc->ds | 0x03) != cur)
51 loadsegment(ds, sc->ds | 0x03);
52 savesegment(es, cur);
53 if ((sc->es | 0x03) != cur)
54 loadsegment(es, sc->es | 0x03);
55 }
56
57 /*
58 * Do a signal return; undo the signal stack.
59 */
ia32_restore_sigcontext(struct pt_regs * regs,struct sigcontext_32 __user * usc)60 static int ia32_restore_sigcontext(struct pt_regs *regs,
61 struct sigcontext_32 __user *usc)
62 {
63 struct sigcontext_32 sc;
64
65 /* Always make any pending restarted system calls return -EINTR */
66 current->restart_block.fn = do_no_restart_syscall;
67
68 if (unlikely(copy_from_user(&sc, usc, sizeof(sc))))
69 return -EFAULT;
70
71 /* Get only the ia32 registers. */
72 regs->bx = sc.bx;
73 regs->cx = sc.cx;
74 regs->dx = sc.dx;
75 regs->si = sc.si;
76 regs->di = sc.di;
77 regs->bp = sc.bp;
78 regs->ax = sc.ax;
79 regs->sp = sc.sp;
80 regs->ip = sc.ip;
81
82 /* Get CS/SS and force CPL3 */
83 regs->cs = sc.cs | 0x03;
84 regs->ss = sc.ss | 0x03;
85
86 regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
87 /* disable syscall checks */
88 regs->orig_ax = -1;
89
90 /*
91 * Reload fs and gs if they have changed in the signal
92 * handler. This does not handle long fs/gs base changes in
93 * the handler, but does not clobber them at least in the
94 * normal case.
95 */
96 reload_segments(&sc);
97 return fpu__restore_sig(compat_ptr(sc.fpstate), 1);
98 }
99
COMPAT_SYSCALL_DEFINE0(sigreturn)100 COMPAT_SYSCALL_DEFINE0(sigreturn)
101 {
102 struct pt_regs *regs = current_pt_regs();
103 struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
104 sigset_t set;
105
106 if (!access_ok(frame, sizeof(*frame)))
107 goto badframe;
108 if (__get_user(set.sig[0], &frame->sc.oldmask)
109 || __get_user(((__u32 *)&set)[1], &frame->extramask[0]))
110 goto badframe;
111
112 set_current_blocked(&set);
113
114 if (ia32_restore_sigcontext(regs, &frame->sc))
115 goto badframe;
116 return regs->ax;
117
118 badframe:
119 signal_fault(regs, frame, "32bit sigreturn");
120 return 0;
121 }
122
COMPAT_SYSCALL_DEFINE0(rt_sigreturn)123 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
124 {
125 struct pt_regs *regs = current_pt_regs();
126 struct rt_sigframe_ia32 __user *frame;
127 sigset_t set;
128
129 frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
130
131 if (!access_ok(frame, sizeof(*frame)))
132 goto badframe;
133 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
134 goto badframe;
135
136 set_current_blocked(&set);
137
138 if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
139 goto badframe;
140
141 if (compat_restore_altstack(&frame->uc.uc_stack))
142 goto badframe;
143
144 return regs->ax;
145
146 badframe:
147 signal_fault(regs, frame, "32bit rt sigreturn");
148 return 0;
149 }
150
151 /*
152 * Set up a signal frame.
153 */
154
155 #define get_user_seg(seg) ({ unsigned int v; savesegment(seg, v); v; })
156
157 static __always_inline int
__unsafe_setup_sigcontext32(struct sigcontext_32 __user * sc,void __user * fpstate,struct pt_regs * regs,unsigned int mask)158 __unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc,
159 void __user *fpstate,
160 struct pt_regs *regs, unsigned int mask)
161 {
162 unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
163 unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);
164 unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);
165 unsafe_put_user(get_user_seg(es), (unsigned int __user *)&sc->es, Efault);
166
167 unsafe_put_user(regs->di, &sc->di, Efault);
168 unsafe_put_user(regs->si, &sc->si, Efault);
169 unsafe_put_user(regs->bp, &sc->bp, Efault);
170 unsafe_put_user(regs->sp, &sc->sp, Efault);
171 unsafe_put_user(regs->bx, &sc->bx, Efault);
172 unsafe_put_user(regs->dx, &sc->dx, Efault);
173 unsafe_put_user(regs->cx, &sc->cx, Efault);
174 unsafe_put_user(regs->ax, &sc->ax, Efault);
175 unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
176 unsafe_put_user(current->thread.error_code, &sc->err, Efault);
177 unsafe_put_user(regs->ip, &sc->ip, Efault);
178 unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
179 unsafe_put_user(regs->flags, &sc->flags, Efault);
180 unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
181 unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
182
183 unsafe_put_user(ptr_to_compat(fpstate), &sc->fpstate, Efault);
184
185 /* non-iBCS2 extensions.. */
186 unsafe_put_user(mask, &sc->oldmask, Efault);
187 unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
188 return 0;
189
190 Efault:
191 return -EFAULT;
192 }
193
194 #define unsafe_put_sigcontext32(sc, fp, regs, set, label) \
195 do { \
196 if (__unsafe_setup_sigcontext32(sc, fp, regs, set->sig[0])) \
197 goto label; \
198 } while(0)
199
200 /*
201 * Determine which stack to use..
202 */
get_sigframe(struct ksignal * ksig,struct pt_regs * regs,size_t frame_size,void __user ** fpstate)203 static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
204 size_t frame_size,
205 void __user **fpstate)
206 {
207 unsigned long sp, fx_aligned, math_size;
208
209 /* Default to using normal stack */
210 sp = regs->sp;
211
212 /* This is the X/Open sanctioned signal stack switching. */
213 if (ksig->ka.sa.sa_flags & SA_ONSTACK)
214 sp = sigsp(sp, ksig);
215 /* This is the legacy signal stack switching. */
216 else if (regs->ss != __USER32_DS &&
217 !(ksig->ka.sa.sa_flags & SA_RESTORER) &&
218 ksig->ka.sa.sa_restorer)
219 sp = (unsigned long) ksig->ka.sa.sa_restorer;
220
221 sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
222 *fpstate = (struct _fpstate_32 __user *) sp;
223 if (copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
224 math_size) < 0)
225 return (void __user *) -1L;
226
227 sp -= frame_size;
228 /* Align the stack pointer according to the i386 ABI,
229 * i.e. so that on function entry ((sp + 4) & 15) == 0. */
230 sp = ((sp + 4) & -16ul) - 4;
231 return (void __user *) sp;
232 }
233
ia32_setup_frame(int sig,struct ksignal * ksig,compat_sigset_t * set,struct pt_regs * regs)234 int ia32_setup_frame(int sig, struct ksignal *ksig,
235 compat_sigset_t *set, struct pt_regs *regs)
236 {
237 struct sigframe_ia32 __user *frame;
238 void __user *restorer;
239 void __user *fp = NULL;
240
241 /* copy_to_user optimizes that into a single 8 byte store */
242 static const struct {
243 u16 poplmovl;
244 u32 val;
245 u16 int80;
246 } __attribute__((packed)) code = {
247 0xb858, /* popl %eax ; movl $...,%eax */
248 __NR_ia32_sigreturn,
249 0x80cd, /* int $0x80 */
250 };
251
252 frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
253
254 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
255 restorer = ksig->ka.sa.sa_restorer;
256 } else {
257 /* Return stub is in 32bit vsyscall page */
258 if (current->mm->context.vdso)
259 restorer = current->mm->context.vdso +
260 vdso_image_32.sym___kernel_sigreturn;
261 else
262 restorer = &frame->retcode;
263 }
264
265 if (!user_access_begin(frame, sizeof(*frame)))
266 return -EFAULT;
267
268 unsafe_put_user(sig, &frame->sig, Efault);
269 unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault);
270 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
271 unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
272 /*
273 * These are actually not used anymore, but left because some
274 * gdb versions depend on them as a marker.
275 */
276 unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
277 user_access_end();
278
279 /* Set up registers for signal handler */
280 regs->sp = (unsigned long) frame;
281 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
282
283 /* Make -mregparm=3 work */
284 regs->ax = sig;
285 regs->dx = 0;
286 regs->cx = 0;
287
288 loadsegment(ds, __USER32_DS);
289 loadsegment(es, __USER32_DS);
290
291 regs->cs = __USER32_CS;
292 regs->ss = __USER32_DS;
293
294 return 0;
295 Efault:
296 user_access_end();
297 return -EFAULT;
298 }
299
ia32_setup_rt_frame(int sig,struct ksignal * ksig,compat_sigset_t * set,struct pt_regs * regs)300 int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
301 compat_sigset_t *set, struct pt_regs *regs)
302 {
303 struct rt_sigframe_ia32 __user *frame;
304 void __user *restorer;
305 void __user *fp = NULL;
306
307 /* unsafe_put_user optimizes that into a single 8 byte store */
308 static const struct {
309 u8 movl;
310 u32 val;
311 u16 int80;
312 u8 pad;
313 } __attribute__((packed)) code = {
314 0xb8,
315 __NR_ia32_rt_sigreturn,
316 0x80cd,
317 0,
318 };
319
320 frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
321
322 if (!user_access_begin(frame, sizeof(*frame)))
323 return -EFAULT;
324
325 unsafe_put_user(sig, &frame->sig, Efault);
326 unsafe_put_user(ptr_to_compat(&frame->info), &frame->pinfo, Efault);
327 unsafe_put_user(ptr_to_compat(&frame->uc), &frame->puc, Efault);
328
329 /* Create the ucontext. */
330 if (static_cpu_has(X86_FEATURE_XSAVE))
331 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
332 else
333 unsafe_put_user(0, &frame->uc.uc_flags, Efault);
334 unsafe_put_user(0, &frame->uc.uc_link, Efault);
335 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
336
337 if (ksig->ka.sa.sa_flags & SA_RESTORER)
338 restorer = ksig->ka.sa.sa_restorer;
339 else
340 restorer = current->mm->context.vdso +
341 vdso_image_32.sym___kernel_rt_sigreturn;
342 unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
343
344 /*
345 * Not actually used anymore, but left because some gdb
346 * versions need it.
347 */
348 unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
349 unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
350 unsafe_put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask, Efault);
351 user_access_end();
352
353 if (__copy_siginfo_to_user32(&frame->info, &ksig->info))
354 return -EFAULT;
355
356 /* Set up registers for signal handler */
357 regs->sp = (unsigned long) frame;
358 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
359
360 /* Make -mregparm=3 work */
361 regs->ax = sig;
362 regs->dx = (unsigned long) &frame->info;
363 regs->cx = (unsigned long) &frame->uc;
364
365 loadsegment(ds, __USER32_DS);
366 loadsegment(es, __USER32_DS);
367
368 regs->cs = __USER32_CS;
369 regs->ss = __USER32_DS;
370
371 return 0;
372 Efault:
373 user_access_end();
374 return -EFAULT;
375 }
376
