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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
5 *
6 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
7 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
8 * 2000-2002 x86-64 support by Andi Kleen
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/sched.h>
14#include <linux/sched/task_stack.h>
15#include <linux/mm.h>
16#include <linux/smp.h>
17#include <linux/kernel.h>
18#include <linux/kstrtox.h>
19#include <linux/errno.h>
20#include <linux/wait.h>
21#include <linux/unistd.h>
22#include <linux/stddef.h>
23#include <linux/personality.h>
24#include <linux/uaccess.h>
25#include <linux/user-return-notifier.h>
26#include <linux/uprobes.h>
27#include <linux/context_tracking.h>
28#include <linux/entry-common.h>
29#include <linux/syscalls.h>
30#include <linux/rseq.h>
31
32#include <asm/processor.h>
33#include <asm/ucontext.h>
34#include <asm/fpu/signal.h>
35#include <asm/fpu/xstate.h>
36#include <asm/vdso.h>
37#include <asm/mce.h>
38#include <asm/sighandling.h>
39#include <asm/vm86.h>
40
41#include <asm/syscall.h>
42#include <asm/sigframe.h>
43#include <asm/signal.h>
44#include <asm/shstk.h>
45
46static inline int is_ia32_compat_frame(struct ksignal *ksig)
47{
48 return IS_ENABLED(CONFIG_IA32_EMULATION) &&
49 ksig->ka.sa.sa_flags & SA_IA32_ABI;
50}
51
52static inline int is_ia32_frame(struct ksignal *ksig)
53{
54 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
55}
56
57static inline int is_x32_frame(struct ksignal *ksig)
58{
59 return IS_ENABLED(CONFIG_X86_X32_ABI) &&
60 ksig->ka.sa.sa_flags & SA_X32_ABI;
61}
62
63/*
64 * Set up a signal frame.
65 */
66
67/* x86 ABI requires 16-byte alignment */
68#define FRAME_ALIGNMENT 16UL
69
70#define MAX_FRAME_PADDING (FRAME_ALIGNMENT - 1)
71
72/*
73 * Determine which stack to use..
74 */
75void __user *
76get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size,
77 void __user **fpstate)
78{
79 struct k_sigaction *ka = &ksig->ka;
80 int ia32_frame = is_ia32_frame(ksig);
81 /* Default to using normal stack */
82 bool nested_altstack = on_sig_stack(regs->sp);
83 bool entering_altstack = false;
84 unsigned long math_size = 0;
85 unsigned long sp = regs->sp;
86 unsigned long buf_fx = 0;
87
88 /* redzone */
89 if (!ia32_frame)
90 sp -= 128;
91
92 /* This is the X/Open sanctioned signal stack switching. */
93 if (ka->sa.sa_flags & SA_ONSTACK) {
94 /*
95 * This checks nested_altstack via sas_ss_flags(). Sensible
96 * programs use SS_AUTODISARM, which disables that check, and
97 * programs that don't use SS_AUTODISARM get compatible.
98 */
99 if (sas_ss_flags(sp) == 0) {
100 sp = current->sas_ss_sp + current->sas_ss_size;
101 entering_altstack = true;
102 }
103 } else if (ia32_frame &&
104 !nested_altstack &&
105 regs->ss != __USER_DS &&
106 !(ka->sa.sa_flags & SA_RESTORER) &&
107 ka->sa.sa_restorer) {
108 /* This is the legacy signal stack switching. */
109 sp = (unsigned long) ka->sa.sa_restorer;
110 entering_altstack = true;
111 }
112
113 sp = fpu__alloc_mathframe(sp, ia32_frame, &buf_fx, &math_size);
114 *fpstate = (void __user *)sp;
115
116 sp -= frame_size;
117
118 if (ia32_frame)
119 /*
120 * Align the stack pointer according to the i386 ABI,
121 * i.e. so that on function entry ((sp + 4) & 15) == 0.
122 */
123 sp = ((sp + 4) & -FRAME_ALIGNMENT) - 4;
124 else
125 sp = round_down(sp, FRAME_ALIGNMENT) - 8;
126
127 /*
128 * If we are on the alternate signal stack and would overflow it, don't.
129 * Return an always-bogus address instead so we will die with SIGSEGV.
130 */
131 if (unlikely((nested_altstack || entering_altstack) &&
132 !__on_sig_stack(sp))) {
133
134 if (show_unhandled_signals && printk_ratelimit())
135 pr_info("%s[%d] overflowed sigaltstack\n",
136 current->comm, task_pid_nr(current));
137
138 return (void __user *)-1L;
139 }
140
141 /* save i387 and extended state */
142 if (!copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size))
143 return (void __user *)-1L;
144
145 return (void __user *)sp;
146}
147
148/*
149 * There are four different struct types for signal frame: sigframe_ia32,
150 * rt_sigframe_ia32, rt_sigframe_x32, and rt_sigframe. Use the worst case
151 * -- the largest size. It means the size for 64-bit apps is a bit more
152 * than needed, but this keeps the code simple.
153 */
154#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
155# define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct sigframe_ia32)
156#else
157# define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct rt_sigframe)
158#endif
159
160/*
161 * The FP state frame contains an XSAVE buffer which must be 64-byte aligned.
162 * If a signal frame starts at an unaligned address, extra space is required.
163 * This is the max alignment padding, conservatively.
164 */
165#define MAX_XSAVE_PADDING 63UL
166
167/*
168 * The frame data is composed of the following areas and laid out as:
169 *
170 * -------------------------
171 * | alignment padding |
172 * -------------------------
173 * | (f)xsave frame |
174 * -------------------------
175 * | fsave header |
176 * -------------------------
177 * | alignment padding |
178 * -------------------------
179 * | siginfo + ucontext |
180 * -------------------------
181 */
182
183/* max_frame_size tells userspace the worst case signal stack size. */
184static unsigned long __ro_after_init max_frame_size;
185static unsigned int __ro_after_init fpu_default_state_size;
186
187static int __init init_sigframe_size(void)
188{
189 fpu_default_state_size = fpu__get_fpstate_size();
190
191 max_frame_size = MAX_FRAME_SIGINFO_UCTXT_SIZE + MAX_FRAME_PADDING;
192
193 max_frame_size += fpu_default_state_size + MAX_XSAVE_PADDING;
194
195 /* Userspace expects an aligned size. */
196 max_frame_size = round_up(max_frame_size, FRAME_ALIGNMENT);
197
198 pr_info("max sigframe size: %lu\n", max_frame_size);
199 return 0;
200}
201early_initcall(init_sigframe_size);
202
203unsigned long get_sigframe_size(void)
204{
205 return max_frame_size;
206}
207
208static int
209setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
210{
211 /* Perform fixup for the pre-signal frame. */
212 rseq_signal_deliver(ksig, regs);
213
214 /* Set up the stack frame */
215 if (is_ia32_frame(ksig)) {
216 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
217 return ia32_setup_rt_frame(ksig, regs);
218 else
219 return ia32_setup_frame(ksig, regs);
220 } else if (is_x32_frame(ksig)) {
221 return x32_setup_rt_frame(ksig, regs);
222 } else {
223 return x64_setup_rt_frame(ksig, regs);
224 }
225}
226
227static void
228handle_signal(struct ksignal *ksig, struct pt_regs *regs)
229{
230 bool stepping, failed;
231 struct fpu *fpu = ¤t->thread.fpu;
232
233 if (v8086_mode(regs))
234 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
235
236 /* Are we from a system call? */
237 if (syscall_get_nr(current, regs) != -1) {
238 /* If so, check system call restarting.. */
239 switch (syscall_get_error(current, regs)) {
240 case -ERESTART_RESTARTBLOCK:
241 case -ERESTARTNOHAND:
242 regs->ax = -EINTR;
243 break;
244
245 case -ERESTARTSYS:
246 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
247 regs->ax = -EINTR;
248 break;
249 }
250 fallthrough;
251 case -ERESTARTNOINTR:
252 regs->ax = regs->orig_ax;
253 regs->ip -= 2;
254 break;
255 }
256 }
257
258 /*
259 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
260 * so that register information in the sigcontext is correct and
261 * then notify the tracer before entering the signal handler.
262 */
263 stepping = test_thread_flag(TIF_SINGLESTEP);
264 if (stepping)
265 user_disable_single_step(current);
266
267 failed = (setup_rt_frame(ksig, regs) < 0);
268 if (!failed) {
269 /*
270 * Clear the direction flag as per the ABI for function entry.
271 *
272 * Clear RF when entering the signal handler, because
273 * it might disable possible debug exception from the
274 * signal handler.
275 *
276 * Clear TF for the case when it wasn't set by debugger to
277 * avoid the recursive send_sigtrap() in SIGTRAP handler.
278 */
279 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
280 /*
281 * Ensure the signal handler starts with the new fpu state.
282 */
283 fpu__clear_user_states(fpu);
284 }
285 signal_setup_done(failed, ksig, stepping);
286}
287
288static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
289{
290#ifdef CONFIG_IA32_EMULATION
291 if (current->restart_block.arch_data & TS_COMPAT)
292 return __NR_ia32_restart_syscall;
293#endif
294#ifdef CONFIG_X86_X32_ABI
295 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
296#else
297 return __NR_restart_syscall;
298#endif
299}
300
301/*
302 * Note that 'init' is a special process: it doesn't get signals it doesn't
303 * want to handle. Thus you cannot kill init even with a SIGKILL even by
304 * mistake.
305 */
306void arch_do_signal_or_restart(struct pt_regs *regs)
307{
308 struct ksignal ksig;
309
310 if (get_signal(&ksig)) {
311 /* Whee! Actually deliver the signal. */
312 handle_signal(&ksig, regs);
313 return;
314 }
315
316 /* Did we come from a system call? */
317 if (syscall_get_nr(current, regs) != -1) {
318 /* Restart the system call - no handlers present */
319 switch (syscall_get_error(current, regs)) {
320 case -ERESTARTNOHAND:
321 case -ERESTARTSYS:
322 case -ERESTARTNOINTR:
323 regs->ax = regs->orig_ax;
324 regs->ip -= 2;
325 break;
326
327 case -ERESTART_RESTARTBLOCK:
328 regs->ax = get_nr_restart_syscall(regs);
329 regs->ip -= 2;
330 break;
331 }
332 }
333
334 /*
335 * If there's no signal to deliver, we just put the saved sigmask
336 * back.
337 */
338 restore_saved_sigmask();
339}
340
341void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
342{
343 struct task_struct *me = current;
344
345 if (show_unhandled_signals && printk_ratelimit()) {
346 printk("%s"
347 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
348 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
349 me->comm, me->pid, where, frame,
350 regs->ip, regs->sp, regs->orig_ax);
351 print_vma_addr(KERN_CONT " in ", regs->ip);
352 pr_cont("\n");
353 }
354
355 force_sig(SIGSEGV);
356}
357
358#ifdef CONFIG_DYNAMIC_SIGFRAME
359#ifdef CONFIG_STRICT_SIGALTSTACK_SIZE
360static bool strict_sigaltstack_size __ro_after_init = true;
361#else
362static bool strict_sigaltstack_size __ro_after_init = false;
363#endif
364
365static int __init strict_sas_size(char *arg)
366{
367 return kstrtobool(arg, &strict_sigaltstack_size) == 0;
368}
369__setup("strict_sas_size", strict_sas_size);
370
371/*
372 * MINSIGSTKSZ is 2048 and can't be changed despite the fact that AVX512
373 * exceeds that size already. As such programs might never use the
374 * sigaltstack they just continued to work. While always checking against
375 * the real size would be correct, this might be considered a regression.
376 *
377 * Therefore avoid the sanity check, unless enforced by kernel
378 * configuration or command line option.
379 *
380 * When dynamic FPU features are supported, the check is also enforced when
381 * the task has permissions to use dynamic features. Tasks which have no
382 * permission are checked against the size of the non-dynamic feature set
383 * if strict checking is enabled. This avoids forcing all tasks on the
384 * system to allocate large sigaltstacks even if they are never going
385 * to use a dynamic feature. As this is serialized via sighand::siglock
386 * any permission request for a dynamic feature either happened already
387 * or will see the newly install sigaltstack size in the permission checks.
388 */
389bool sigaltstack_size_valid(size_t ss_size)
390{
391 unsigned long fsize = max_frame_size - fpu_default_state_size;
392 u64 mask;
393
394 lockdep_assert_held(¤t->sighand->siglock);
395
396 if (!fpu_state_size_dynamic() && !strict_sigaltstack_size)
397 return true;
398
399 fsize += current->group_leader->thread.fpu.perm.__user_state_size;
400 if (likely(ss_size > fsize))
401 return true;
402
403 if (strict_sigaltstack_size)
404 return ss_size > fsize;
405
406 mask = current->group_leader->thread.fpu.perm.__state_perm;
407 if (mask & XFEATURE_MASK_USER_DYNAMIC)
408 return ss_size > fsize;
409
410 return true;
411}
412#endif /* CONFIG_DYNAMIC_SIGFRAME */
1/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
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 * 2000-2002 x86-64 support by Andi Kleen
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/sched.h>
13#include <linux/mm.h>
14#include <linux/smp.h>
15#include <linux/kernel.h>
16#include <linux/errno.h>
17#include <linux/wait.h>
18#include <linux/tracehook.h>
19#include <linux/unistd.h>
20#include <linux/stddef.h>
21#include <linux/personality.h>
22#include <linux/uaccess.h>
23#include <linux/user-return-notifier.h>
24#include <linux/uprobes.h>
25#include <linux/context_tracking.h>
26
27#include <asm/processor.h>
28#include <asm/ucontext.h>
29#include <asm/i387.h>
30#include <asm/fpu-internal.h>
31#include <asm/vdso.h>
32#include <asm/mce.h>
33#include <asm/sighandling.h>
34
35#ifdef CONFIG_X86_64
36#include <asm/proto.h>
37#include <asm/ia32_unistd.h>
38#include <asm/sys_ia32.h>
39#endif /* CONFIG_X86_64 */
40
41#include <asm/syscall.h>
42#include <asm/syscalls.h>
43
44#include <asm/sigframe.h>
45
46#define COPY(x) do { \
47 get_user_ex(regs->x, &sc->x); \
48} while (0)
49
50#define GET_SEG(seg) ({ \
51 unsigned short tmp; \
52 get_user_ex(tmp, &sc->seg); \
53 tmp; \
54})
55
56#define COPY_SEG(seg) do { \
57 regs->seg = GET_SEG(seg); \
58} while (0)
59
60#define COPY_SEG_CPL3(seg) do { \
61 regs->seg = GET_SEG(seg) | 3; \
62} while (0)
63
64int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
65 unsigned long *pax)
66{
67 void __user *buf;
68 unsigned int tmpflags;
69 unsigned int err = 0;
70
71 /* Always make any pending restarted system calls return -EINTR */
72 current_thread_info()->restart_block.fn = do_no_restart_syscall;
73
74 get_user_try {
75
76#ifdef CONFIG_X86_32
77 set_user_gs(regs, GET_SEG(gs));
78 COPY_SEG(fs);
79 COPY_SEG(es);
80 COPY_SEG(ds);
81#endif /* CONFIG_X86_32 */
82
83 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
84 COPY(dx); COPY(cx); COPY(ip);
85
86#ifdef CONFIG_X86_64
87 COPY(r8);
88 COPY(r9);
89 COPY(r10);
90 COPY(r11);
91 COPY(r12);
92 COPY(r13);
93 COPY(r14);
94 COPY(r15);
95#endif /* CONFIG_X86_64 */
96
97#ifdef CONFIG_X86_32
98 COPY_SEG_CPL3(cs);
99 COPY_SEG_CPL3(ss);
100#else /* !CONFIG_X86_32 */
101 /* Kernel saves and restores only the CS segment register on signals,
102 * which is the bare minimum needed to allow mixed 32/64-bit code.
103 * App's signal handler can save/restore other segments if needed. */
104 COPY_SEG_CPL3(cs);
105#endif /* CONFIG_X86_32 */
106
107 get_user_ex(tmpflags, &sc->flags);
108 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
109 regs->orig_ax = -1; /* disable syscall checks */
110
111 get_user_ex(buf, &sc->fpstate);
112
113 get_user_ex(*pax, &sc->ax);
114 } get_user_catch(err);
115
116 err |= restore_xstate_sig(buf, config_enabled(CONFIG_X86_32));
117
118 return err;
119}
120
121int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
122 struct pt_regs *regs, unsigned long mask)
123{
124 int err = 0;
125
126 put_user_try {
127
128#ifdef CONFIG_X86_32
129 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
130 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
131 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
132 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
133#endif /* CONFIG_X86_32 */
134
135 put_user_ex(regs->di, &sc->di);
136 put_user_ex(regs->si, &sc->si);
137 put_user_ex(regs->bp, &sc->bp);
138 put_user_ex(regs->sp, &sc->sp);
139 put_user_ex(regs->bx, &sc->bx);
140 put_user_ex(regs->dx, &sc->dx);
141 put_user_ex(regs->cx, &sc->cx);
142 put_user_ex(regs->ax, &sc->ax);
143#ifdef CONFIG_X86_64
144 put_user_ex(regs->r8, &sc->r8);
145 put_user_ex(regs->r9, &sc->r9);
146 put_user_ex(regs->r10, &sc->r10);
147 put_user_ex(regs->r11, &sc->r11);
148 put_user_ex(regs->r12, &sc->r12);
149 put_user_ex(regs->r13, &sc->r13);
150 put_user_ex(regs->r14, &sc->r14);
151 put_user_ex(regs->r15, &sc->r15);
152#endif /* CONFIG_X86_64 */
153
154 put_user_ex(current->thread.trap_nr, &sc->trapno);
155 put_user_ex(current->thread.error_code, &sc->err);
156 put_user_ex(regs->ip, &sc->ip);
157#ifdef CONFIG_X86_32
158 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
159 put_user_ex(regs->flags, &sc->flags);
160 put_user_ex(regs->sp, &sc->sp_at_signal);
161 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
162#else /* !CONFIG_X86_32 */
163 put_user_ex(regs->flags, &sc->flags);
164 put_user_ex(regs->cs, &sc->cs);
165 put_user_ex(0, &sc->gs);
166 put_user_ex(0, &sc->fs);
167#endif /* CONFIG_X86_32 */
168
169 put_user_ex(fpstate, &sc->fpstate);
170
171 /* non-iBCS2 extensions.. */
172 put_user_ex(mask, &sc->oldmask);
173 put_user_ex(current->thread.cr2, &sc->cr2);
174 } put_user_catch(err);
175
176 return err;
177}
178
179/*
180 * Set up a signal frame.
181 */
182
183/*
184 * Determine which stack to use..
185 */
186static unsigned long align_sigframe(unsigned long sp)
187{
188#ifdef CONFIG_X86_32
189 /*
190 * Align the stack pointer according to the i386 ABI,
191 * i.e. so that on function entry ((sp + 4) & 15) == 0.
192 */
193 sp = ((sp + 4) & -16ul) - 4;
194#else /* !CONFIG_X86_32 */
195 sp = round_down(sp, 16) - 8;
196#endif
197 return sp;
198}
199
200static inline void __user *
201get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
202 void __user **fpstate)
203{
204 /* Default to using normal stack */
205 unsigned long math_size = 0;
206 unsigned long sp = regs->sp;
207 unsigned long buf_fx = 0;
208 int onsigstack = on_sig_stack(sp);
209
210 /* redzone */
211 if (config_enabled(CONFIG_X86_64))
212 sp -= 128;
213
214 if (!onsigstack) {
215 /* This is the X/Open sanctioned signal stack switching. */
216 if (ka->sa.sa_flags & SA_ONSTACK) {
217 if (current->sas_ss_size)
218 sp = current->sas_ss_sp + current->sas_ss_size;
219 } else if (config_enabled(CONFIG_X86_32) &&
220 (regs->ss & 0xffff) != __USER_DS &&
221 !(ka->sa.sa_flags & SA_RESTORER) &&
222 ka->sa.sa_restorer) {
223 /* This is the legacy signal stack switching. */
224 sp = (unsigned long) ka->sa.sa_restorer;
225 }
226 }
227
228 if (used_math()) {
229 sp = alloc_mathframe(sp, config_enabled(CONFIG_X86_32),
230 &buf_fx, &math_size);
231 *fpstate = (void __user *)sp;
232 }
233
234 sp = align_sigframe(sp - frame_size);
235
236 /*
237 * If we are on the alternate signal stack and would overflow it, don't.
238 * Return an always-bogus address instead so we will die with SIGSEGV.
239 */
240 if (onsigstack && !likely(on_sig_stack(sp)))
241 return (void __user *)-1L;
242
243 /* save i387 and extended state */
244 if (used_math() &&
245 save_xstate_sig(*fpstate, (void __user *)buf_fx, math_size) < 0)
246 return (void __user *)-1L;
247
248 return (void __user *)sp;
249}
250
251#ifdef CONFIG_X86_32
252static const struct {
253 u16 poplmovl;
254 u32 val;
255 u16 int80;
256} __attribute__((packed)) retcode = {
257 0xb858, /* popl %eax; movl $..., %eax */
258 __NR_sigreturn,
259 0x80cd, /* int $0x80 */
260};
261
262static const struct {
263 u8 movl;
264 u32 val;
265 u16 int80;
266 u8 pad;
267} __attribute__((packed)) rt_retcode = {
268 0xb8, /* movl $..., %eax */
269 __NR_rt_sigreturn,
270 0x80cd, /* int $0x80 */
271 0
272};
273
274static int
275__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
276 struct pt_regs *regs)
277{
278 struct sigframe __user *frame;
279 void __user *restorer;
280 int err = 0;
281 void __user *fpstate = NULL;
282
283 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
284
285 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
286 return -EFAULT;
287
288 if (__put_user(sig, &frame->sig))
289 return -EFAULT;
290
291 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
292 return -EFAULT;
293
294 if (_NSIG_WORDS > 1) {
295 if (__copy_to_user(&frame->extramask, &set->sig[1],
296 sizeof(frame->extramask)))
297 return -EFAULT;
298 }
299
300 if (current->mm->context.vdso)
301 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
302 else
303 restorer = &frame->retcode;
304 if (ksig->ka.sa.sa_flags & SA_RESTORER)
305 restorer = ksig->ka.sa.sa_restorer;
306
307 /* Set up to return from userspace. */
308 err |= __put_user(restorer, &frame->pretcode);
309
310 /*
311 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
312 *
313 * WE DO NOT USE IT ANY MORE! It's only left here for historical
314 * reasons and because gdb uses it as a signature to notice
315 * signal handler stack frames.
316 */
317 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
318
319 if (err)
320 return -EFAULT;
321
322 /* Set up registers for signal handler */
323 regs->sp = (unsigned long)frame;
324 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
325 regs->ax = (unsigned long)sig;
326 regs->dx = 0;
327 regs->cx = 0;
328
329 regs->ds = __USER_DS;
330 regs->es = __USER_DS;
331 regs->ss = __USER_DS;
332 regs->cs = __USER_CS;
333
334 return 0;
335}
336
337static int __setup_rt_frame(int sig, struct ksignal *ksig,
338 sigset_t *set, struct pt_regs *regs)
339{
340 struct rt_sigframe __user *frame;
341 void __user *restorer;
342 int err = 0;
343 void __user *fpstate = NULL;
344
345 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
346
347 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
348 return -EFAULT;
349
350 put_user_try {
351 put_user_ex(sig, &frame->sig);
352 put_user_ex(&frame->info, &frame->pinfo);
353 put_user_ex(&frame->uc, &frame->puc);
354
355 /* Create the ucontext. */
356 if (cpu_has_xsave)
357 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
358 else
359 put_user_ex(0, &frame->uc.uc_flags);
360 put_user_ex(0, &frame->uc.uc_link);
361 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
362
363 /* Set up to return from userspace. */
364 restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
365 if (ksig->ka.sa.sa_flags & SA_RESTORER)
366 restorer = ksig->ka.sa.sa_restorer;
367 put_user_ex(restorer, &frame->pretcode);
368
369 /*
370 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
371 *
372 * WE DO NOT USE IT ANY MORE! It's only left here for historical
373 * reasons and because gdb uses it as a signature to notice
374 * signal handler stack frames.
375 */
376 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
377 } put_user_catch(err);
378
379 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
380 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
381 regs, set->sig[0]);
382 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
383
384 if (err)
385 return -EFAULT;
386
387 /* Set up registers for signal handler */
388 regs->sp = (unsigned long)frame;
389 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
390 regs->ax = (unsigned long)sig;
391 regs->dx = (unsigned long)&frame->info;
392 regs->cx = (unsigned long)&frame->uc;
393
394 regs->ds = __USER_DS;
395 regs->es = __USER_DS;
396 regs->ss = __USER_DS;
397 regs->cs = __USER_CS;
398
399 return 0;
400}
401#else /* !CONFIG_X86_32 */
402static int __setup_rt_frame(int sig, struct ksignal *ksig,
403 sigset_t *set, struct pt_regs *regs)
404{
405 struct rt_sigframe __user *frame;
406 void __user *fp = NULL;
407 int err = 0;
408
409 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
410
411 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
412 return -EFAULT;
413
414 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
415 if (copy_siginfo_to_user(&frame->info, &ksig->info))
416 return -EFAULT;
417 }
418
419 put_user_try {
420 /* Create the ucontext. */
421 if (cpu_has_xsave)
422 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
423 else
424 put_user_ex(0, &frame->uc.uc_flags);
425 put_user_ex(0, &frame->uc.uc_link);
426 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
427
428 /* Set up to return from userspace. If provided, use a stub
429 already in userspace. */
430 /* x86-64 should always use SA_RESTORER. */
431 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
432 put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
433 } else {
434 /* could use a vstub here */
435 err |= -EFAULT;
436 }
437 } put_user_catch(err);
438
439 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
440 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
441
442 if (err)
443 return -EFAULT;
444
445 /* Set up registers for signal handler */
446 regs->di = sig;
447 /* In case the signal handler was declared without prototypes */
448 regs->ax = 0;
449
450 /* This also works for non SA_SIGINFO handlers because they expect the
451 next argument after the signal number on the stack. */
452 regs->si = (unsigned long)&frame->info;
453 regs->dx = (unsigned long)&frame->uc;
454 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
455
456 regs->sp = (unsigned long)frame;
457
458 /* Set up the CS register to run signal handlers in 64-bit mode,
459 even if the handler happens to be interrupting 32-bit code. */
460 regs->cs = __USER_CS;
461
462 return 0;
463}
464#endif /* CONFIG_X86_32 */
465
466static int x32_setup_rt_frame(struct ksignal *ksig,
467 compat_sigset_t *set,
468 struct pt_regs *regs)
469{
470#ifdef CONFIG_X86_X32_ABI
471 struct rt_sigframe_x32 __user *frame;
472 void __user *restorer;
473 int err = 0;
474 void __user *fpstate = NULL;
475
476 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
477
478 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
479 return -EFAULT;
480
481 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
482 if (copy_siginfo_to_user32(&frame->info, &ksig->info))
483 return -EFAULT;
484 }
485
486 put_user_try {
487 /* Create the ucontext. */
488 if (cpu_has_xsave)
489 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
490 else
491 put_user_ex(0, &frame->uc.uc_flags);
492 put_user_ex(0, &frame->uc.uc_link);
493 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
494 put_user_ex(0, &frame->uc.uc__pad0);
495
496 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
497 restorer = ksig->ka.sa.sa_restorer;
498 } else {
499 /* could use a vstub here */
500 restorer = NULL;
501 err |= -EFAULT;
502 }
503 put_user_ex(restorer, &frame->pretcode);
504 } put_user_catch(err);
505
506 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
507 regs, set->sig[0]);
508 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
509
510 if (err)
511 return -EFAULT;
512
513 /* Set up registers for signal handler */
514 regs->sp = (unsigned long) frame;
515 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
516
517 /* We use the x32 calling convention here... */
518 regs->di = ksig->sig;
519 regs->si = (unsigned long) &frame->info;
520 regs->dx = (unsigned long) &frame->uc;
521
522 loadsegment(ds, __USER_DS);
523 loadsegment(es, __USER_DS);
524
525 regs->cs = __USER_CS;
526 regs->ss = __USER_DS;
527#endif /* CONFIG_X86_X32_ABI */
528
529 return 0;
530}
531
532/*
533 * Do a signal return; undo the signal stack.
534 */
535#ifdef CONFIG_X86_32
536asmlinkage unsigned long sys_sigreturn(void)
537{
538 struct pt_regs *regs = current_pt_regs();
539 struct sigframe __user *frame;
540 unsigned long ax;
541 sigset_t set;
542
543 frame = (struct sigframe __user *)(regs->sp - 8);
544
545 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
546 goto badframe;
547 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
548 && __copy_from_user(&set.sig[1], &frame->extramask,
549 sizeof(frame->extramask))))
550 goto badframe;
551
552 set_current_blocked(&set);
553
554 if (restore_sigcontext(regs, &frame->sc, &ax))
555 goto badframe;
556 return ax;
557
558badframe:
559 signal_fault(regs, frame, "sigreturn");
560
561 return 0;
562}
563#endif /* CONFIG_X86_32 */
564
565asmlinkage long sys_rt_sigreturn(void)
566{
567 struct pt_regs *regs = current_pt_regs();
568 struct rt_sigframe __user *frame;
569 unsigned long ax;
570 sigset_t set;
571
572 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
573 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
574 goto badframe;
575 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
576 goto badframe;
577
578 set_current_blocked(&set);
579
580 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
581 goto badframe;
582
583 if (restore_altstack(&frame->uc.uc_stack))
584 goto badframe;
585
586 return ax;
587
588badframe:
589 signal_fault(regs, frame, "rt_sigreturn");
590 return 0;
591}
592
593/*
594 * OK, we're invoking a handler:
595 */
596static int signr_convert(int sig)
597{
598#ifdef CONFIG_X86_32
599 struct thread_info *info = current_thread_info();
600
601 if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
602 return info->exec_domain->signal_invmap[sig];
603#endif /* CONFIG_X86_32 */
604 return sig;
605}
606
607static int
608setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
609{
610 int usig = signr_convert(ksig->sig);
611 sigset_t *set = sigmask_to_save();
612 compat_sigset_t *cset = (compat_sigset_t *) set;
613
614 /* Set up the stack frame */
615 if (is_ia32_frame()) {
616 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
617 return ia32_setup_rt_frame(usig, ksig, cset, regs);
618 else
619 return ia32_setup_frame(usig, ksig, cset, regs);
620 } else if (is_x32_frame()) {
621 return x32_setup_rt_frame(ksig, cset, regs);
622 } else {
623 return __setup_rt_frame(ksig->sig, ksig, set, regs);
624 }
625}
626
627static void
628handle_signal(struct ksignal *ksig, struct pt_regs *regs)
629{
630 bool failed;
631 /* Are we from a system call? */
632 if (syscall_get_nr(current, regs) >= 0) {
633 /* If so, check system call restarting.. */
634 switch (syscall_get_error(current, regs)) {
635 case -ERESTART_RESTARTBLOCK:
636 case -ERESTARTNOHAND:
637 regs->ax = -EINTR;
638 break;
639
640 case -ERESTARTSYS:
641 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
642 regs->ax = -EINTR;
643 break;
644 }
645 /* fallthrough */
646 case -ERESTARTNOINTR:
647 regs->ax = regs->orig_ax;
648 regs->ip -= 2;
649 break;
650 }
651 }
652
653 /*
654 * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
655 * flag so that register information in the sigcontext is correct.
656 */
657 if (unlikely(regs->flags & X86_EFLAGS_TF) &&
658 likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
659 regs->flags &= ~X86_EFLAGS_TF;
660
661 failed = (setup_rt_frame(ksig, regs) < 0);
662 if (!failed) {
663 /*
664 * Clear the direction flag as per the ABI for function entry.
665 *
666 * Clear RF when entering the signal handler, because
667 * it might disable possible debug exception from the
668 * signal handler.
669 *
670 * Clear TF when entering the signal handler, but
671 * notify any tracer that was single-stepping it.
672 * The tracer may want to single-step inside the
673 * handler too.
674 */
675 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
676 }
677 signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP));
678}
679
680#ifdef CONFIG_X86_32
681#define NR_restart_syscall __NR_restart_syscall
682#else /* !CONFIG_X86_32 */
683#define NR_restart_syscall \
684 test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
685#endif /* CONFIG_X86_32 */
686
687/*
688 * Note that 'init' is a special process: it doesn't get signals it doesn't
689 * want to handle. Thus you cannot kill init even with a SIGKILL even by
690 * mistake.
691 */
692static void do_signal(struct pt_regs *regs)
693{
694 struct ksignal ksig;
695
696 if (get_signal(&ksig)) {
697 /* Whee! Actually deliver the signal. */
698 handle_signal(&ksig, regs);
699 return;
700 }
701
702 /* Did we come from a system call? */
703 if (syscall_get_nr(current, regs) >= 0) {
704 /* Restart the system call - no handlers present */
705 switch (syscall_get_error(current, regs)) {
706 case -ERESTARTNOHAND:
707 case -ERESTARTSYS:
708 case -ERESTARTNOINTR:
709 regs->ax = regs->orig_ax;
710 regs->ip -= 2;
711 break;
712
713 case -ERESTART_RESTARTBLOCK:
714 regs->ax = NR_restart_syscall;
715 regs->ip -= 2;
716 break;
717 }
718 }
719
720 /*
721 * If there's no signal to deliver, we just put the saved sigmask
722 * back.
723 */
724 restore_saved_sigmask();
725}
726
727/*
728 * notification of userspace execution resumption
729 * - triggered by the TIF_WORK_MASK flags
730 */
731__visible void
732do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
733{
734 user_exit();
735
736#ifdef CONFIG_X86_MCE
737 /* notify userspace of pending MCEs */
738 if (thread_info_flags & _TIF_MCE_NOTIFY)
739 mce_notify_process();
740#endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
741
742 if (thread_info_flags & _TIF_UPROBE)
743 uprobe_notify_resume(regs);
744
745 /* deal with pending signal delivery */
746 if (thread_info_flags & _TIF_SIGPENDING)
747 do_signal(regs);
748
749 if (thread_info_flags & _TIF_NOTIFY_RESUME) {
750 clear_thread_flag(TIF_NOTIFY_RESUME);
751 tracehook_notify_resume(regs);
752 }
753 if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
754 fire_user_return_notifiers();
755
756 user_enter();
757}
758
759void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
760{
761 struct task_struct *me = current;
762
763 if (show_unhandled_signals && printk_ratelimit()) {
764 printk("%s"
765 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
766 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
767 me->comm, me->pid, where, frame,
768 regs->ip, regs->sp, regs->orig_ax);
769 print_vma_addr(" in ", regs->ip);
770 pr_cont("\n");
771 }
772
773 force_sig(SIGSEGV, me);
774}
775
776#ifdef CONFIG_X86_X32_ABI
777asmlinkage long sys32_x32_rt_sigreturn(void)
778{
779 struct pt_regs *regs = current_pt_regs();
780 struct rt_sigframe_x32 __user *frame;
781 sigset_t set;
782 unsigned long ax;
783
784 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
785
786 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
787 goto badframe;
788 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
789 goto badframe;
790
791 set_current_blocked(&set);
792
793 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
794 goto badframe;
795
796 if (compat_restore_altstack(&frame->uc.uc_stack))
797 goto badframe;
798
799 return ax;
800
801badframe:
802 signal_fault(regs, frame, "x32 rt_sigreturn");
803 return 0;
804}
805#endif