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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 *
5 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
6 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
7 * 2000-12-* x86-64 compatibility mode signal handling by Andi Kleen
8 */
9
10#include <linux/sched.h>
11#include <linux/sched/task_stack.h>
12#include <linux/mm.h>
13#include <linux/smp.h>
14#include <linux/kernel.h>
15#include <linux/errno.h>
16#include <linux/wait.h>
17#include <linux/unistd.h>
18#include <linux/stddef.h>
19#include <linux/personality.h>
20#include <linux/compat.h>
21#include <linux/binfmts.h>
22#include <linux/syscalls.h>
23#include <asm/ucontext.h>
24#include <linux/uaccess.h>
25#include <asm/fpu/signal.h>
26#include <asm/ptrace.h>
27#include <asm/user32.h>
28#include <uapi/asm/sigcontext.h>
29#include <asm/proto.h>
30#include <asm/vdso.h>
31#include <asm/sigframe.h>
32#include <asm/sighandling.h>
33#include <asm/smap.h>
34
35#ifdef CONFIG_IA32_EMULATION
36#include <asm/ia32_unistd.h>
37
38static inline void reload_segments(struct sigcontext_32 *sc)
39{
40 unsigned int cur;
41
42 savesegment(gs, cur);
43 if ((sc->gs | 0x03) != cur)
44 load_gs_index(sc->gs | 0x03);
45 savesegment(fs, cur);
46 if ((sc->fs | 0x03) != cur)
47 loadsegment(fs, sc->fs | 0x03);
48 savesegment(ds, cur);
49 if ((sc->ds | 0x03) != cur)
50 loadsegment(ds, sc->ds | 0x03);
51 savesegment(es, cur);
52 if ((sc->es | 0x03) != cur)
53 loadsegment(es, sc->es | 0x03);
54}
55
56#define sigset32_t compat_sigset_t
57#define restore_altstack32 compat_restore_altstack
58#define unsafe_save_altstack32 unsafe_compat_save_altstack
59
60#else
61
62#define sigset32_t sigset_t
63#define __NR_ia32_sigreturn __NR_sigreturn
64#define __NR_ia32_rt_sigreturn __NR_rt_sigreturn
65#define restore_altstack32 restore_altstack
66#define unsafe_save_altstack32 unsafe_save_altstack
67#define __copy_siginfo_to_user32 copy_siginfo_to_user
68
69#endif
70
71/*
72 * Do a signal return; undo the signal stack.
73 */
74static bool ia32_restore_sigcontext(struct pt_regs *regs,
75 struct sigcontext_32 __user *usc)
76{
77 struct sigcontext_32 sc;
78
79 /* Always make any pending restarted system calls return -EINTR */
80 current->restart_block.fn = do_no_restart_syscall;
81
82 if (unlikely(copy_from_user(&sc, usc, sizeof(sc))))
83 return false;
84
85 /* Get only the ia32 registers. */
86 regs->bx = sc.bx;
87 regs->cx = sc.cx;
88 regs->dx = sc.dx;
89 regs->si = sc.si;
90 regs->di = sc.di;
91 regs->bp = sc.bp;
92 regs->ax = sc.ax;
93 regs->sp = sc.sp;
94 regs->ip = sc.ip;
95
96 /* Get CS/SS and force CPL3 */
97 regs->cs = sc.cs | 0x03;
98 regs->ss = sc.ss | 0x03;
99
100 regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
101 /* disable syscall checks */
102 regs->orig_ax = -1;
103
104#ifdef CONFIG_IA32_EMULATION
105 /*
106 * Reload fs and gs if they have changed in the signal
107 * handler. This does not handle long fs/gs base changes in
108 * the handler, but does not clobber them at least in the
109 * normal case.
110 */
111 reload_segments(&sc);
112#else
113 loadsegment(gs, sc.gs);
114 regs->fs = sc.fs;
115 regs->es = sc.es;
116 regs->ds = sc.ds;
117#endif
118
119 return fpu__restore_sig(compat_ptr(sc.fpstate), 1);
120}
121
122SYSCALL32_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 || __get_user(((__u32 *)&set)[1], &frame->extramask[0]))
132 goto badframe;
133
134 set_current_blocked(&set);
135
136 if (!ia32_restore_sigcontext(regs, &frame->sc))
137 goto badframe;
138 return regs->ax;
139
140badframe:
141 signal_fault(regs, frame, "32bit sigreturn");
142 return 0;
143}
144
145SYSCALL32_DEFINE0(rt_sigreturn)
146{
147 struct pt_regs *regs = current_pt_regs();
148 struct rt_sigframe_ia32 __user *frame;
149 sigset_t set;
150
151 frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
152
153 if (!access_ok(frame, sizeof(*frame)))
154 goto badframe;
155 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
156 goto badframe;
157
158 set_current_blocked(&set);
159
160 if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
161 goto badframe;
162
163 if (restore_altstack32(&frame->uc.uc_stack))
164 goto badframe;
165
166 return regs->ax;
167
168badframe:
169 signal_fault(regs, frame, "32bit rt sigreturn");
170 return 0;
171}
172
173/*
174 * Set up a signal frame.
175 */
176
177#define get_user_seg(seg) ({ unsigned int v; savesegment(seg, v); v; })
178
179static __always_inline int
180__unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc,
181 void __user *fpstate,
182 struct pt_regs *regs, unsigned int mask)
183{
184 unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
185#ifdef CONFIG_IA32_EMULATION
186 unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);
187 unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);
188 unsafe_put_user(get_user_seg(es), (unsigned int __user *)&sc->es, Efault);
189#else
190 unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
191 unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
192 unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
193#endif
194
195 unsafe_put_user(regs->di, &sc->di, Efault);
196 unsafe_put_user(regs->si, &sc->si, Efault);
197 unsafe_put_user(regs->bp, &sc->bp, Efault);
198 unsafe_put_user(regs->sp, &sc->sp, Efault);
199 unsafe_put_user(regs->bx, &sc->bx, Efault);
200 unsafe_put_user(regs->dx, &sc->dx, Efault);
201 unsafe_put_user(regs->cx, &sc->cx, Efault);
202 unsafe_put_user(regs->ax, &sc->ax, Efault);
203 unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
204 unsafe_put_user(current->thread.error_code, &sc->err, Efault);
205 unsafe_put_user(regs->ip, &sc->ip, Efault);
206 unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
207 unsafe_put_user(regs->flags, &sc->flags, Efault);
208 unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
209 unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
210
211 unsafe_put_user(ptr_to_compat(fpstate), &sc->fpstate, Efault);
212
213 /* non-iBCS2 extensions.. */
214 unsafe_put_user(mask, &sc->oldmask, Efault);
215 unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
216 return 0;
217
218Efault:
219 return -EFAULT;
220}
221
222#define unsafe_put_sigcontext32(sc, fp, regs, set, label) \
223do { \
224 if (__unsafe_setup_sigcontext32(sc, fp, regs, set->sig[0])) \
225 goto label; \
226} while(0)
227
228int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs)
229{
230 sigset32_t *set = (sigset32_t *) sigmask_to_save();
231 struct sigframe_ia32 __user *frame;
232 void __user *restorer;
233 void __user *fp = NULL;
234
235 /* copy_to_user optimizes that into a single 8 byte store */
236 static const struct {
237 u16 poplmovl;
238 u32 val;
239 u16 int80;
240 } __attribute__((packed)) code = {
241 0xb858, /* popl %eax ; movl $...,%eax */
242 __NR_ia32_sigreturn,
243 0x80cd, /* int $0x80 */
244 };
245
246 frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
247
248 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
249 restorer = ksig->ka.sa.sa_restorer;
250 } else {
251 /* Return stub is in 32bit vsyscall page */
252 if (current->mm->context.vdso)
253 restorer = current->mm->context.vdso +
254 vdso_image_32.sym___kernel_sigreturn;
255 else
256 restorer = &frame->retcode;
257 }
258
259 if (!user_access_begin(frame, sizeof(*frame)))
260 return -EFAULT;
261
262 unsafe_put_user(ksig->sig, &frame->sig, Efault);
263 unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault);
264 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
265 unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
266 /*
267 * These are actually not used anymore, but left because some
268 * gdb versions depend on them as a marker.
269 */
270 unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
271 user_access_end();
272
273 /* Set up registers for signal handler */
274 regs->sp = (unsigned long) frame;
275 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
276
277 /* Make -mregparm=3 work */
278 regs->ax = ksig->sig;
279 regs->dx = 0;
280 regs->cx = 0;
281
282#ifdef CONFIG_IA32_EMULATION
283 loadsegment(ds, __USER_DS);
284 loadsegment(es, __USER_DS);
285#else
286 regs->ds = __USER_DS;
287 regs->es = __USER_DS;
288#endif
289
290 regs->cs = __USER32_CS;
291 regs->ss = __USER_DS;
292
293 return 0;
294Efault:
295 user_access_end();
296 return -EFAULT;
297}
298
299int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
300{
301 sigset32_t *set = (sigset32_t *) sigmask_to_save();
302 struct rt_sigframe_ia32 __user *frame;
303 void __user *restorer;
304 void __user *fp = NULL;
305
306 /* unsafe_put_user optimizes that into a single 8 byte store */
307 static const struct {
308 u8 movl;
309 u32 val;
310 u16 int80;
311 u8 pad;
312 } __attribute__((packed)) code = {
313 0xb8,
314 __NR_ia32_rt_sigreturn,
315 0x80cd,
316 0,
317 };
318
319 frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
320
321 if (!user_access_begin(frame, sizeof(*frame)))
322 return -EFAULT;
323
324 unsafe_put_user(ksig->sig, &frame->sig, Efault);
325 unsafe_put_user(ptr_to_compat(&frame->info), &frame->pinfo, Efault);
326 unsafe_put_user(ptr_to_compat(&frame->uc), &frame->puc, Efault);
327
328 /* Create the ucontext. */
329 if (static_cpu_has(X86_FEATURE_XSAVE))
330 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
331 else
332 unsafe_put_user(0, &frame->uc.uc_flags, Efault);
333 unsafe_put_user(0, &frame->uc.uc_link, Efault);
334 unsafe_save_altstack32(&frame->uc.uc_stack, regs->sp, Efault);
335
336 if (ksig->ka.sa.sa_flags & SA_RESTORER)
337 restorer = ksig->ka.sa.sa_restorer;
338 else
339 restorer = current->mm->context.vdso +
340 vdso_image_32.sym___kernel_rt_sigreturn;
341 unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
342
343 /*
344 * Not actually used anymore, but left because some gdb
345 * versions need it.
346 */
347 unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
348 unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
349 unsafe_put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask, Efault);
350 user_access_end();
351
352 if (__copy_siginfo_to_user32(&frame->info, &ksig->info))
353 return -EFAULT;
354
355 /* Set up registers for signal handler */
356 regs->sp = (unsigned long) frame;
357 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
358
359 /* Make -mregparm=3 work */
360 regs->ax = ksig->sig;
361 regs->dx = (unsigned long) &frame->info;
362 regs->cx = (unsigned long) &frame->uc;
363
364#ifdef CONFIG_IA32_EMULATION
365 loadsegment(ds, __USER_DS);
366 loadsegment(es, __USER_DS);
367#else
368 regs->ds = __USER_DS;
369 regs->es = __USER_DS;
370#endif
371
372 regs->cs = __USER32_CS;
373 regs->ss = __USER_DS;
374
375 return 0;
376Efault:
377 user_access_end();
378 return -EFAULT;
379}