1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/kernel.h>
10 #include <linux/errno.h>
11 #include <linux/unistd.h>
12 #include <linux/uaccess.h>
13 #include <linux/syscalls.h>
15 #include <asm/ucontext.h>
16 #include <asm/fpu/signal.h>
17 #include <asm/sighandling.h>
19 #include <asm/syscall.h>
20 #include <asm/sigframe.h>
21 #include <asm/signal.h>
24 * If regs->ss will cause an IRET fault, change it. Otherwise leave it
25 * alone. Using this generally makes no sense unless
26 * user_64bit_mode(regs) would return true.
28 static void force_valid_ss(struct pt_regs *regs)
31 asm volatile ("lar %[old_ss], %[ar]\n\t"
32 "jz 1f\n\t" /* If invalid: */
33 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */
36 : [old_ss] "rm" ((u16)regs->ss));
39 * For a valid 64-bit user context, we need DPL 3, type
40 * read-write data or read-write exp-down data, and S and P
41 * set. We can't use VERW because VERW doesn't check the
44 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
45 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
46 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
50 static bool restore_sigcontext(struct pt_regs *regs,
51 struct sigcontext __user *usc,
52 unsigned long uc_flags)
56 /* Always make any pending restarted system calls return -EINTR */
57 current->restart_block.fn = do_no_restart_syscall;
59 if (copy_from_user(&sc, usc, offsetof(struct sigcontext, reserved1)))
80 /* Get CS/SS and force CPL3 */
81 regs->cs = sc.cs | 0x03;
82 regs->ss = sc.ss | 0x03;
84 regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
85 /* disable syscall checks */
89 * Fix up SS if needed for the benefit of old DOSEMU and
92 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
95 return fpu__restore_sig((void __user *)sc.fpstate, 0);
98 static __always_inline int
99 __unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
100 struct pt_regs *regs, unsigned long mask)
102 unsafe_put_user(regs->di, &sc->di, Efault);
103 unsafe_put_user(regs->si, &sc->si, Efault);
104 unsafe_put_user(regs->bp, &sc->bp, Efault);
105 unsafe_put_user(regs->sp, &sc->sp, Efault);
106 unsafe_put_user(regs->bx, &sc->bx, Efault);
107 unsafe_put_user(regs->dx, &sc->dx, Efault);
108 unsafe_put_user(regs->cx, &sc->cx, Efault);
109 unsafe_put_user(regs->ax, &sc->ax, Efault);
110 unsafe_put_user(regs->r8, &sc->r8, Efault);
111 unsafe_put_user(regs->r9, &sc->r9, Efault);
112 unsafe_put_user(regs->r10, &sc->r10, Efault);
113 unsafe_put_user(regs->r11, &sc->r11, Efault);
114 unsafe_put_user(regs->r12, &sc->r12, Efault);
115 unsafe_put_user(regs->r13, &sc->r13, Efault);
116 unsafe_put_user(regs->r14, &sc->r14, Efault);
117 unsafe_put_user(regs->r15, &sc->r15, Efault);
119 unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
120 unsafe_put_user(current->thread.error_code, &sc->err, Efault);
121 unsafe_put_user(regs->ip, &sc->ip, Efault);
122 unsafe_put_user(regs->flags, &sc->flags, Efault);
123 unsafe_put_user(regs->cs, &sc->cs, Efault);
124 unsafe_put_user(0, &sc->gs, Efault);
125 unsafe_put_user(0, &sc->fs, Efault);
126 unsafe_put_user(regs->ss, &sc->ss, Efault);
128 unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault);
130 /* non-iBCS2 extensions.. */
131 unsafe_put_user(mask, &sc->oldmask, Efault);
132 unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
138 #define unsafe_put_sigcontext(sc, fp, regs, set, label) \
140 if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \
144 #define unsafe_put_sigmask(set, frame, label) \
145 unsafe_put_user(*(__u64 *)(set), \
146 (__u64 __user *)&(frame)->uc.uc_sigmask, \
149 static unsigned long frame_uc_flags(struct pt_regs *regs)
153 if (boot_cpu_has(X86_FEATURE_XSAVE))
154 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
156 flags = UC_SIGCONTEXT_SS;
158 if (likely(user_64bit_mode(regs)))
159 flags |= UC_STRICT_RESTORE_SS;
164 int x64_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
166 sigset_t *set = sigmask_to_save();
167 struct rt_sigframe __user *frame;
168 void __user *fp = NULL;
169 unsigned long uc_flags;
171 /* x86-64 should always use SA_RESTORER. */
172 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
175 frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe), &fp);
176 uc_flags = frame_uc_flags(regs);
178 if (!user_access_begin(frame, sizeof(*frame)))
181 /* Create the ucontext. */
182 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
183 unsafe_put_user(0, &frame->uc.uc_link, Efault);
184 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
186 /* Set up to return from userspace. If provided, use a stub
187 already in userspace. */
188 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
189 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
190 unsafe_put_sigmask(set, frame, Efault);
193 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
194 if (copy_siginfo_to_user(&frame->info, &ksig->info))
198 /* Set up registers for signal handler */
199 regs->di = ksig->sig;
200 /* In case the signal handler was declared without prototypes */
203 /* This also works for non SA_SIGINFO handlers because they expect the
204 next argument after the signal number on the stack. */
205 regs->si = (unsigned long)&frame->info;
206 regs->dx = (unsigned long)&frame->uc;
207 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
209 regs->sp = (unsigned long)frame;
212 * Set up the CS and SS registers to run signal handlers in
213 * 64-bit mode, even if the handler happens to be interrupting
214 * 32-bit or 16-bit code.
216 * SS is subtle. In 64-bit mode, we don't need any particular
217 * SS descriptor, but we do need SS to be valid. It's possible
218 * that the old SS is entirely bogus -- this can happen if the
219 * signal we're trying to deliver is #GP or #SS caused by a bad
220 * SS value. We also have a compatibility issue here: DOSEMU
221 * relies on the contents of the SS register indicating the
222 * SS value at the time of the signal, even though that code in
223 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
224 * avoids relying on sigreturn to restore SS; instead it uses
225 * a trampoline.) So we do our best: if the old SS was valid,
226 * we keep it. Otherwise we replace it.
228 regs->cs = __USER_CS;
230 if (unlikely(regs->ss != __USER_DS))
231 force_valid_ss(regs);
241 * Do a signal return; undo the signal stack.
243 SYSCALL_DEFINE0(rt_sigreturn)
245 struct pt_regs *regs = current_pt_regs();
246 struct rt_sigframe __user *frame;
248 unsigned long uc_flags;
250 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
251 if (!access_ok(frame, sizeof(*frame)))
253 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
255 if (__get_user(uc_flags, &frame->uc.uc_flags))
258 set_current_blocked(&set);
260 if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
263 if (restore_altstack(&frame->uc.uc_stack))
269 signal_fault(regs, frame, "rt_sigreturn");
273 #ifdef CONFIG_X86_X32_ABI
274 static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
275 const struct kernel_siginfo *from)
277 struct compat_siginfo new;
279 copy_siginfo_to_external32(&new, from);
280 if (from->si_signo == SIGCHLD) {
281 new._sifields._sigchld_x32._utime = from->si_utime;
282 new._sifields._sigchld_x32._stime = from->si_stime;
284 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
289 int copy_siginfo_to_user32(struct compat_siginfo __user *to,
290 const struct kernel_siginfo *from)
292 if (in_x32_syscall())
293 return x32_copy_siginfo_to_user(to, from);
294 return __copy_siginfo_to_user32(to, from);
297 int x32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
299 compat_sigset_t *set = (compat_sigset_t *) sigmask_to_save();
300 struct rt_sigframe_x32 __user *frame;
301 unsigned long uc_flags;
302 void __user *restorer;
303 void __user *fp = NULL;
305 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
308 frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
310 uc_flags = frame_uc_flags(regs);
312 if (!user_access_begin(frame, sizeof(*frame)))
315 /* Create the ucontext. */
316 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
317 unsafe_put_user(0, &frame->uc.uc_link, Efault);
318 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
319 unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
320 restorer = ksig->ka.sa.sa_restorer;
321 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
322 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
323 unsafe_put_sigmask(set, frame, Efault);
326 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
327 if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
331 /* Set up registers for signal handler */
332 regs->sp = (unsigned long) frame;
333 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
335 /* We use the x32 calling convention here... */
336 regs->di = ksig->sig;
337 regs->si = (unsigned long) &frame->info;
338 regs->dx = (unsigned long) &frame->uc;
340 loadsegment(ds, __USER_DS);
341 loadsegment(es, __USER_DS);
343 regs->cs = __USER_CS;
344 regs->ss = __USER_DS;
353 COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
355 struct pt_regs *regs = current_pt_regs();
356 struct rt_sigframe_x32 __user *frame;
358 unsigned long uc_flags;
360 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
362 if (!access_ok(frame, sizeof(*frame)))
364 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
366 if (__get_user(uc_flags, &frame->uc.uc_flags))
369 set_current_blocked(&set);
371 if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
374 if (compat_restore_altstack(&frame->uc.uc_stack))
380 signal_fault(regs, frame, "x32 rt_sigreturn");
383 #endif /* CONFIG_X86_X32_ABI */
386 void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact)
391 if (in_ia32_syscall())
392 act->sa.sa_flags |= SA_IA32_ABI;
393 if (in_x32_syscall())
394 act->sa.sa_flags |= SA_X32_ABI;
396 #endif /* CONFIG_COMPAT */
399 * If adding a new si_code, there is probably new data in
400 * the siginfo. Make sure folks bumping the si_code
401 * limits also have to look at this code. Make sure any
402 * new fields are handled in copy_siginfo_to_user32()!
404 static_assert(NSIGILL == 11);
405 static_assert(NSIGFPE == 15);
406 static_assert(NSIGSEGV == 9);
407 static_assert(NSIGBUS == 5);
408 static_assert(NSIGTRAP == 6);
409 static_assert(NSIGCHLD == 6);
410 static_assert(NSIGSYS == 2);
412 /* This is part of the ABI and can never change in size: */
413 static_assert(sizeof(siginfo_t) == 128);
415 /* This is a part of the ABI and can never change in alignment */
416 static_assert(__alignof__(siginfo_t) == 8);
419 * The offsets of all the (unioned) si_fields are fixed
420 * in the ABI, of course. Make sure none of them ever
421 * move and are always at the beginning:
423 static_assert(offsetof(siginfo_t, si_signo) == 0);
424 static_assert(offsetof(siginfo_t, si_errno) == 4);
425 static_assert(offsetof(siginfo_t, si_code) == 8);
428 * Ensure that the size of each si_field never changes.
429 * If it does, it is a sign that the
430 * copy_siginfo_to_user32() code below needs to updated
431 * along with the size in the CHECK_SI_SIZE().
433 * We repeat this check for both the generic and compat
436 * Note: it is OK for these to grow as long as the whole
437 * structure stays within the padding size (checked
441 #define CHECK_SI_OFFSET(name) \
442 static_assert(offsetof(siginfo_t, _sifields) == \
443 offsetof(siginfo_t, _sifields.name))
444 #define CHECK_SI_SIZE(name, size) \
445 static_assert(sizeof_field(siginfo_t, _sifields.name) == size)
447 CHECK_SI_OFFSET(_kill);
448 CHECK_SI_SIZE (_kill, 2*sizeof(int));
449 static_assert(offsetof(siginfo_t, si_pid) == 0x10);
450 static_assert(offsetof(siginfo_t, si_uid) == 0x14);
452 CHECK_SI_OFFSET(_timer);
453 CHECK_SI_SIZE (_timer, 6*sizeof(int));
454 static_assert(offsetof(siginfo_t, si_tid) == 0x10);
455 static_assert(offsetof(siginfo_t, si_overrun) == 0x14);
456 static_assert(offsetof(siginfo_t, si_value) == 0x18);
458 CHECK_SI_OFFSET(_rt);
459 CHECK_SI_SIZE (_rt, 4*sizeof(int));
460 static_assert(offsetof(siginfo_t, si_pid) == 0x10);
461 static_assert(offsetof(siginfo_t, si_uid) == 0x14);
462 static_assert(offsetof(siginfo_t, si_value) == 0x18);
464 CHECK_SI_OFFSET(_sigchld);
465 CHECK_SI_SIZE (_sigchld, 8*sizeof(int));
466 static_assert(offsetof(siginfo_t, si_pid) == 0x10);
467 static_assert(offsetof(siginfo_t, si_uid) == 0x14);
468 static_assert(offsetof(siginfo_t, si_status) == 0x18);
469 static_assert(offsetof(siginfo_t, si_utime) == 0x20);
470 static_assert(offsetof(siginfo_t, si_stime) == 0x28);
472 #ifdef CONFIG_X86_X32_ABI
473 /* no _sigchld_x32 in the generic siginfo_t */
474 static_assert(sizeof_field(compat_siginfo_t, _sifields._sigchld_x32) ==
476 static_assert(offsetof(compat_siginfo_t, _sifields) ==
477 offsetof(compat_siginfo_t, _sifields._sigchld_x32));
478 static_assert(offsetof(compat_siginfo_t, _sifields._sigchld_x32._utime) == 0x18);
479 static_assert(offsetof(compat_siginfo_t, _sifields._sigchld_x32._stime) == 0x20);
482 CHECK_SI_OFFSET(_sigfault);
483 CHECK_SI_SIZE (_sigfault, 8*sizeof(int));
484 static_assert(offsetof(siginfo_t, si_addr) == 0x10);
486 static_assert(offsetof(siginfo_t, si_trapno) == 0x18);
488 static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x18);
490 static_assert(offsetof(siginfo_t, si_lower) == 0x20);
491 static_assert(offsetof(siginfo_t, si_upper) == 0x28);
493 static_assert(offsetof(siginfo_t, si_pkey) == 0x20);
495 static_assert(offsetof(siginfo_t, si_perf_data) == 0x18);
496 static_assert(offsetof(siginfo_t, si_perf_type) == 0x20);
497 static_assert(offsetof(siginfo_t, si_perf_flags) == 0x24);
499 CHECK_SI_OFFSET(_sigpoll);
500 CHECK_SI_SIZE (_sigpoll, 4*sizeof(int));
501 static_assert(offsetof(siginfo_t, si_band) == 0x10);
502 static_assert(offsetof(siginfo_t, si_fd) == 0x18);
504 CHECK_SI_OFFSET(_sigsys);
505 CHECK_SI_SIZE (_sigsys, 4*sizeof(int));
506 static_assert(offsetof(siginfo_t, si_call_addr) == 0x10);
507 static_assert(offsetof(siginfo_t, si_syscall) == 0x18);
508 static_assert(offsetof(siginfo_t, si_arch) == 0x1C);
510 /* any new si_fields should be added here */