// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs * * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes * 2000-2002 x86-64 support by Andi Kleen */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_X86_64 #include #include #include #include #endif /* CONFIG_X86_64 */ #include #include #include #ifdef CONFIG_X86_64 /* * If regs->ss will cause an IRET fault, change it. Otherwise leave it * alone. Using this generally makes no sense unless * user_64bit_mode(regs) would return true. */ static void force_valid_ss(struct pt_regs *regs) { u32 ar; asm volatile ("lar %[old_ss], %[ar]\n\t" "jz 1f\n\t" /* If invalid: */ "xorl %[ar], %[ar]\n\t" /* set ar = 0 */ "1:" : [ar] "=r" (ar) : [old_ss] "rm" ((u16)regs->ss)); /* * For a valid 64-bit user context, we need DPL 3, type * read-write data or read-write exp-down data, and S and P * set. We can't use VERW because VERW doesn't check the * P bit. */ ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK; if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) && ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN)) regs->ss = __USER_DS; } # define CONTEXT_COPY_SIZE offsetof(struct sigcontext, reserved1) #else # define CONTEXT_COPY_SIZE sizeof(struct sigcontext) #endif static bool restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *usc, unsigned long uc_flags) { struct sigcontext sc; /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE)) return false; #ifdef CONFIG_X86_32 loadsegment(gs, sc.gs); regs->fs = sc.fs; regs->es = sc.es; regs->ds = sc.ds; #endif /* CONFIG_X86_32 */ regs->bx = sc.bx; regs->cx = sc.cx; regs->dx = sc.dx; regs->si = sc.si; regs->di = sc.di; regs->bp = sc.bp; regs->ax = sc.ax; regs->sp = sc.sp; regs->ip = sc.ip; #ifdef CONFIG_X86_64 regs->r8 = sc.r8; regs->r9 = sc.r9; regs->r10 = sc.r10; regs->r11 = sc.r11; regs->r12 = sc.r12; regs->r13 = sc.r13; regs->r14 = sc.r14; regs->r15 = sc.r15; #endif /* CONFIG_X86_64 */ /* Get CS/SS and force CPL3 */ regs->cs = sc.cs | 0x03; regs->ss = sc.ss | 0x03; regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS); /* disable syscall checks */ regs->orig_ax = -1; #ifdef CONFIG_X86_64 /* * Fix up SS if needed for the benefit of old DOSEMU and * CRIU. */ if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs))) force_valid_ss(regs); #endif return fpu__restore_sig((void __user *)sc.fpstate, IS_ENABLED(CONFIG_X86_32)); } static __always_inline int __unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate, struct pt_regs *regs, unsigned long mask) { #ifdef CONFIG_X86_32 unsigned int gs; savesegment(gs, gs); unsafe_put_user(gs, (unsigned int __user *)&sc->gs, Efault); unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault); unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault); unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault); #endif /* CONFIG_X86_32 */ unsafe_put_user(regs->di, &sc->di, Efault); unsafe_put_user(regs->si, &sc->si, Efault); unsafe_put_user(regs->bp, &sc->bp, Efault); unsafe_put_user(regs->sp, &sc->sp, Efault); unsafe_put_user(regs->bx, &sc->bx, Efault); unsafe_put_user(regs->dx, &sc->dx, Efault); unsafe_put_user(regs->cx, &sc->cx, Efault); unsafe_put_user(regs->ax, &sc->ax, Efault); #ifdef CONFIG_X86_64 unsafe_put_user(regs->r8, &sc->r8, Efault); unsafe_put_user(regs->r9, &sc->r9, Efault); unsafe_put_user(regs->r10, &sc->r10, Efault); unsafe_put_user(regs->r11, &sc->r11, Efault); unsafe_put_user(regs->r12, &sc->r12, Efault); unsafe_put_user(regs->r13, &sc->r13, Efault); unsafe_put_user(regs->r14, &sc->r14, Efault); unsafe_put_user(regs->r15, &sc->r15, Efault); #endif /* CONFIG_X86_64 */ unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault); unsafe_put_user(current->thread.error_code, &sc->err, Efault); unsafe_put_user(regs->ip, &sc->ip, Efault); #ifdef CONFIG_X86_32 unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault); unsafe_put_user(regs->flags, &sc->flags, Efault); unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault); unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault); #else /* !CONFIG_X86_32 */ unsafe_put_user(regs->flags, &sc->flags, Efault); unsafe_put_user(regs->cs, &sc->cs, Efault); unsafe_put_user(0, &sc->gs, Efault); unsafe_put_user(0, &sc->fs, Efault); unsafe_put_user(regs->ss, &sc->ss, Efault); #endif /* CONFIG_X86_32 */ unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault); /* non-iBCS2 extensions.. */ unsafe_put_user(mask, &sc->oldmask, Efault); unsafe_put_user(current->thread.cr2, &sc->cr2, Efault); return 0; Efault: return -EFAULT; } #define unsafe_put_sigcontext(sc, fp, regs, set, label) \ do { \ if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \ goto label; \ } while(0); #define unsafe_put_sigmask(set, frame, label) \ unsafe_put_user(*(__u64 *)(set), \ (__u64 __user *)&(frame)->uc.uc_sigmask, \ label) /* * Set up a signal frame. */ /* x86 ABI requires 16-byte alignment */ #define FRAME_ALIGNMENT 16UL #define MAX_FRAME_PADDING (FRAME_ALIGNMENT - 1) /* * Determine which stack to use.. */ static unsigned long align_sigframe(unsigned long sp) { #ifdef CONFIG_X86_32 /* * Align the stack pointer according to the i386 ABI, * i.e. so that on function entry ((sp + 4) & 15) == 0. */ sp = ((sp + 4) & -FRAME_ALIGNMENT) - 4; #else /* !CONFIG_X86_32 */ sp = round_down(sp, FRAME_ALIGNMENT) - 8; #endif return sp; } static void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, void __user **fpstate) { /* Default to using normal stack */ bool nested_altstack = on_sig_stack(regs->sp); bool entering_altstack = false; unsigned long math_size = 0; unsigned long sp = regs->sp; unsigned long buf_fx = 0; /* redzone */ if (IS_ENABLED(CONFIG_X86_64)) sp -= 128; /* This is the X/Open sanctioned signal stack switching. */ if (ka->sa.sa_flags & SA_ONSTACK) { /* * This checks nested_altstack via sas_ss_flags(). Sensible * programs use SS_AUTODISARM, which disables that check, and * programs that don't use SS_AUTODISARM get compatible. */ if (sas_ss_flags(sp) == 0) { sp = current->sas_ss_sp + current->sas_ss_size; entering_altstack = true; } } else if (IS_ENABLED(CONFIG_X86_32) && !nested_altstack && regs->ss != __USER_DS && !(ka->sa.sa_flags & SA_RESTORER) && ka->sa.sa_restorer) { /* This is the legacy signal stack switching. */ sp = (unsigned long) ka->sa.sa_restorer; entering_altstack = true; } sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32), &buf_fx, &math_size); *fpstate = (void __user *)sp; sp = align_sigframe(sp - frame_size); /* * If we are on the alternate signal stack and would overflow it, don't. * Return an always-bogus address instead so we will die with SIGSEGV. */ if (unlikely((nested_altstack || entering_altstack) && !__on_sig_stack(sp))) { if (show_unhandled_signals && printk_ratelimit()) pr_info("%s[%d] overflowed sigaltstack\n", current->comm, task_pid_nr(current)); return (void __user *)-1L; } /* save i387 and extended state */ if (!copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size)) return (void __user *)-1L; return (void __user *)sp; } #ifdef CONFIG_X86_32 static const struct { u16 poplmovl; u32 val; u16 int80; } __attribute__((packed)) retcode = { 0xb858, /* popl %eax; movl $..., %eax */ __NR_sigreturn, 0x80cd, /* int $0x80 */ }; static const struct { u8 movl; u32 val; u16 int80; u8 pad; } __attribute__((packed)) rt_retcode = { 0xb8, /* movl $..., %eax */ __NR_rt_sigreturn, 0x80cd, /* int $0x80 */ 0 }; static int __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct sigframe __user *frame; void __user *restorer; void __user *fp = NULL; frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); if (!user_access_begin(frame, sizeof(*frame))) return -EFAULT; unsafe_put_user(sig, &frame->sig, Efault); unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault); unsafe_put_user(set->sig[1], &frame->extramask[0], Efault); if (current->mm->context.vdso) restorer = current->mm->context.vdso + vdso_image_32.sym___kernel_sigreturn; else restorer = &frame->retcode; if (ksig->ka.sa.sa_flags & SA_RESTORER) restorer = ksig->ka.sa.sa_restorer; /* Set up to return from userspace. */ unsafe_put_user(restorer, &frame->pretcode, Efault); /* * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80 * * WE DO NOT USE IT ANY MORE! It's only left here for historical * reasons and because gdb uses it as a signature to notice * signal handler stack frames. */ unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault); user_access_end(); /* Set up registers for signal handler */ regs->sp = (unsigned long)frame; regs->ip = (unsigned long)ksig->ka.sa.sa_handler; regs->ax = (unsigned long)sig; regs->dx = 0; regs->cx = 0; regs->ds = __USER_DS; regs->es = __USER_DS; regs->ss = __USER_DS; regs->cs = __USER_CS; return 0; Efault: user_access_end(); return -EFAULT; } static int __setup_rt_frame(int sig, struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct rt_sigframe __user *frame; void __user *restorer; void __user *fp = NULL; frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); if (!user_access_begin(frame, sizeof(*frame))) return -EFAULT; unsafe_put_user(sig, &frame->sig, Efault); unsafe_put_user(&frame->info, &frame->pinfo, Efault); unsafe_put_user(&frame->uc, &frame->puc, Efault); /* Create the ucontext. */ if (static_cpu_has(X86_FEATURE_XSAVE)) unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault); else unsafe_put_user(0, &frame->uc.uc_flags, Efault); unsafe_put_user(0, &frame->uc.uc_link, Efault); unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); /* Set up to return from userspace. */ restorer = current->mm->context.vdso + vdso_image_32.sym___kernel_rt_sigreturn; if (ksig->ka.sa.sa_flags & SA_RESTORER) restorer = ksig->ka.sa.sa_restorer; unsafe_put_user(restorer, &frame->pretcode, Efault); /* * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 * * WE DO NOT USE IT ANY MORE! It's only left here for historical * reasons and because gdb uses it as a signature to notice * signal handler stack frames. */ unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault); unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); unsafe_put_sigmask(set, frame, Efault); user_access_end(); if (copy_siginfo_to_user(&frame->info, &ksig->info)) return -EFAULT; /* Set up registers for signal handler */ regs->sp = (unsigned long)frame; regs->ip = (unsigned long)ksig->ka.sa.sa_handler; regs->ax = (unsigned long)sig; regs->dx = (unsigned long)&frame->info; regs->cx = (unsigned long)&frame->uc; regs->ds = __USER_DS; regs->es = __USER_DS; regs->ss = __USER_DS; regs->cs = __USER_CS; return 0; Efault: user_access_end(); return -EFAULT; } #else /* !CONFIG_X86_32 */ static unsigned long frame_uc_flags(struct pt_regs *regs) { unsigned long flags; if (boot_cpu_has(X86_FEATURE_XSAVE)) flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS; else flags = UC_SIGCONTEXT_SS; if (likely(user_64bit_mode(regs))) flags |= UC_STRICT_RESTORE_SS; return flags; } static int __setup_rt_frame(int sig, struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct rt_sigframe __user *frame; void __user *fp = NULL; unsigned long uc_flags; /* x86-64 should always use SA_RESTORER. */ if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) return -EFAULT; frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); uc_flags = frame_uc_flags(regs); if (!user_access_begin(frame, sizeof(*frame))) return -EFAULT; /* Create the ucontext. */ unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); unsafe_put_user(0, &frame->uc.uc_link, Efault); unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); /* Set up to return from userspace. If provided, use a stub already in userspace. */ unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault); unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); unsafe_put_sigmask(set, frame, Efault); user_access_end(); if (ksig->ka.sa.sa_flags & SA_SIGINFO) { if (copy_siginfo_to_user(&frame->info, &ksig->info)) return -EFAULT; } /* Set up registers for signal handler */ regs->di = sig; /* In case the signal handler was declared without prototypes */ regs->ax = 0; /* This also works for non SA_SIGINFO handlers because they expect the next argument after the signal number on the stack. */ regs->si = (unsigned long)&frame->info; regs->dx = (unsigned long)&frame->uc; regs->ip = (unsigned long) ksig->ka.sa.sa_handler; regs->sp = (unsigned long)frame; /* * Set up the CS and SS registers to run signal handlers in * 64-bit mode, even if the handler happens to be interrupting * 32-bit or 16-bit code. * * SS is subtle. In 64-bit mode, we don't need any particular * SS descriptor, but we do need SS to be valid. It's possible * that the old SS is entirely bogus -- this can happen if the * signal we're trying to deliver is #GP or #SS caused by a bad * SS value. We also have a compatibility issue here: DOSEMU * relies on the contents of the SS register indicating the * SS value at the time of the signal, even though that code in * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU * avoids relying on sigreturn to restore SS; instead it uses * a trampoline.) So we do our best: if the old SS was valid, * we keep it. Otherwise we replace it. */ regs->cs = __USER_CS; if (unlikely(regs->ss != __USER_DS)) force_valid_ss(regs); return 0; Efault: user_access_end(); return -EFAULT; } #endif /* CONFIG_X86_32 */ #ifdef CONFIG_X86_X32_ABI static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to, const struct kernel_siginfo *from) { struct compat_siginfo new; copy_siginfo_to_external32(&new, from); if (from->si_signo == SIGCHLD) { new._sifields._sigchld_x32._utime = from->si_utime; new._sifields._sigchld_x32._stime = from->si_stime; } if (copy_to_user(to, &new, sizeof(struct compat_siginfo))) return -EFAULT; return 0; } int copy_siginfo_to_user32(struct compat_siginfo __user *to, const struct kernel_siginfo *from) { if (in_x32_syscall()) return x32_copy_siginfo_to_user(to, from); return __copy_siginfo_to_user32(to, from); } #endif /* CONFIG_X86_X32_ABI */ static int x32_setup_rt_frame(struct ksignal *ksig, compat_sigset_t *set, struct pt_regs *regs) { #ifdef CONFIG_X86_X32_ABI struct rt_sigframe_x32 __user *frame; unsigned long uc_flags; void __user *restorer; void __user *fp = NULL; if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) return -EFAULT; frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp); uc_flags = frame_uc_flags(regs); if (!user_access_begin(frame, sizeof(*frame))) return -EFAULT; /* Create the ucontext. */ unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); unsafe_put_user(0, &frame->uc.uc_link, Efault); unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); unsafe_put_user(0, &frame->uc.uc__pad0, Efault); restorer = ksig->ka.sa.sa_restorer; unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault); unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault); unsafe_put_sigmask(set, frame, Efault); user_access_end(); if (ksig->ka.sa.sa_flags & SA_SIGINFO) { if (x32_copy_siginfo_to_user(&frame->info, &ksig->info)) return -EFAULT; } /* Set up registers for signal handler */ regs->sp = (unsigned long) frame; regs->ip = (unsigned long) ksig->ka.sa.sa_handler; /* We use the x32 calling convention here... */ regs->di = ksig->sig; regs->si = (unsigned long) &frame->info; regs->dx = (unsigned long) &frame->uc; loadsegment(ds, __USER_DS); loadsegment(es, __USER_DS); regs->cs = __USER_CS; regs->ss = __USER_DS; #endif /* CONFIG_X86_X32_ABI */ return 0; #ifdef CONFIG_X86_X32_ABI Efault: user_access_end(); return -EFAULT; #endif } /* * Do a signal return; undo the signal stack. */ #ifdef CONFIG_X86_32 SYSCALL_DEFINE0(sigreturn) { struct pt_regs *regs = current_pt_regs(); struct sigframe __user *frame; sigset_t set; frame = (struct sigframe __user *)(regs->sp - 8); if (!access_ok(frame, sizeof(*frame))) goto badframe; if (__get_user(set.sig[0], &frame->sc.oldmask) || __get_user(set.sig[1], &frame->extramask[0])) goto badframe; set_current_blocked(&set); /* * x86_32 has no uc_flags bits relevant to restore_sigcontext. * Save a few cycles by skipping the __get_user. */ if (!restore_sigcontext(regs, &frame->sc, 0)) goto badframe; return regs->ax; badframe: signal_fault(regs, frame, "sigreturn"); return 0; } #endif /* CONFIG_X86_32 */ SYSCALL_DEFINE0(rt_sigreturn) { struct pt_regs *regs = current_pt_regs(); struct rt_sigframe __user *frame; sigset_t set; unsigned long uc_flags; frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); if (!access_ok(frame, sizeof(*frame))) goto badframe; if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask)) goto badframe; if (__get_user(uc_flags, &frame->uc.uc_flags)) goto badframe; set_current_blocked(&set); if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) goto badframe; if (restore_altstack(&frame->uc.uc_stack)) goto badframe; return regs->ax; badframe: signal_fault(regs, frame, "rt_sigreturn"); return 0; } /* * There are four different struct types for signal frame: sigframe_ia32, * rt_sigframe_ia32, rt_sigframe_x32, and rt_sigframe. Use the worst case * -- the largest size. It means the size for 64-bit apps is a bit more * than needed, but this keeps the code simple. */ #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) # define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct sigframe_ia32) #else # define MAX_FRAME_SIGINFO_UCTXT_SIZE sizeof(struct rt_sigframe) #endif /* * The FP state frame contains an XSAVE buffer which must be 64-byte aligned. * If a signal frame starts at an unaligned address, extra space is required. * This is the max alignment padding, conservatively. */ #define MAX_XSAVE_PADDING 63UL /* * The frame data is composed of the following areas and laid out as: * * ------------------------- * | alignment padding | * ------------------------- * | (f)xsave frame | * ------------------------- * | fsave header | * ------------------------- * | alignment padding | * ------------------------- * | siginfo + ucontext | * ------------------------- */ /* max_frame_size tells userspace the worst case signal stack size. */ static unsigned long __ro_after_init max_frame_size; static unsigned int __ro_after_init fpu_default_state_size; void __init init_sigframe_size(void) { fpu_default_state_size = fpu__get_fpstate_size(); max_frame_size = MAX_FRAME_SIGINFO_UCTXT_SIZE + MAX_FRAME_PADDING; max_frame_size += fpu_default_state_size + MAX_XSAVE_PADDING; /* Userspace expects an aligned size. */ max_frame_size = round_up(max_frame_size, FRAME_ALIGNMENT); pr_info("max sigframe size: %lu\n", max_frame_size); } unsigned long get_sigframe_size(void) { return max_frame_size; } static inline int is_ia32_compat_frame(struct ksignal *ksig) { return IS_ENABLED(CONFIG_IA32_EMULATION) && ksig->ka.sa.sa_flags & SA_IA32_ABI; } static inline int is_ia32_frame(struct ksignal *ksig) { return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); } static inline int is_x32_frame(struct ksignal *ksig) { return IS_ENABLED(CONFIG_X86_X32_ABI) && ksig->ka.sa.sa_flags & SA_X32_ABI; } static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) { int usig = ksig->sig; sigset_t *set = sigmask_to_save(); compat_sigset_t *cset = (compat_sigset_t *) set; /* Perform fixup for the pre-signal frame. */ rseq_signal_deliver(ksig, regs); /* Set up the stack frame */ if (is_ia32_frame(ksig)) { if (ksig->ka.sa.sa_flags & SA_SIGINFO) return ia32_setup_rt_frame(usig, ksig, cset, regs); else return ia32_setup_frame(usig, ksig, cset, regs); } else if (is_x32_frame(ksig)) { return x32_setup_rt_frame(ksig, cset, regs); } else { return __setup_rt_frame(ksig->sig, ksig, set, regs); } } static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) { bool stepping, failed; struct fpu *fpu = ¤t->thread.fpu; if (v8086_mode(regs)) save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); /* Are we from a system call? */ if (syscall_get_nr(current, regs) != -1) { /* If so, check system call restarting.. */ switch (syscall_get_error(current, regs)) { case -ERESTART_RESTARTBLOCK: case -ERESTARTNOHAND: regs->ax = -EINTR; break; case -ERESTARTSYS: if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { regs->ax = -EINTR; break; } fallthrough; case -ERESTARTNOINTR: regs->ax = regs->orig_ax; regs->ip -= 2; break; } } /* * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now * so that register information in the sigcontext is correct and * then notify the tracer before entering the signal handler. */ stepping = test_thread_flag(TIF_SINGLESTEP); if (stepping) user_disable_single_step(current); failed = (setup_rt_frame(ksig, regs) < 0); if (!failed) { /* * Clear the direction flag as per the ABI for function entry. * * Clear RF when entering the signal handler, because * it might disable possible debug exception from the * signal handler. * * Clear TF for the case when it wasn't set by debugger to * avoid the recursive send_sigtrap() in SIGTRAP handler. */ regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF); /* * Ensure the signal handler starts with the new fpu state. */ fpu__clear_user_states(fpu); } signal_setup_done(failed, ksig, stepping); } static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) { #ifdef CONFIG_IA32_EMULATION if (current->restart_block.arch_data & TS_COMPAT) return __NR_ia32_restart_syscall; #endif #ifdef CONFIG_X86_X32_ABI return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT); #else return __NR_restart_syscall; #endif } /* * Note that 'init' is a special process: it doesn't get signals it doesn't * want to handle. Thus you cannot kill init even with a SIGKILL even by * mistake. */ void arch_do_signal_or_restart(struct pt_regs *regs) { struct ksignal ksig; if (get_signal(&ksig)) { /* Whee! Actually deliver the signal. */ handle_signal(&ksig, regs); return; } /* Did we come from a system call? */ if (syscall_get_nr(current, regs) != -1) { /* Restart the system call - no handlers present */ switch (syscall_get_error(current, regs)) { case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: regs->ax = regs->orig_ax; regs->ip -= 2; break; case -ERESTART_RESTARTBLOCK: regs->ax = get_nr_restart_syscall(regs); regs->ip -= 2; break; } } /* * If there's no signal to deliver, we just put the saved sigmask * back. */ restore_saved_sigmask(); } void signal_fault(struct pt_regs *regs, void __user *frame, char *where) { struct task_struct *me = current; if (show_unhandled_signals && printk_ratelimit()) { printk("%s" "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, me->comm, me->pid, where, frame, regs->ip, regs->sp, regs->orig_ax); print_vma_addr(KERN_CONT " in ", regs->ip); pr_cont("\n"); } force_sig(SIGSEGV); } #ifdef CONFIG_DYNAMIC_SIGFRAME #ifdef CONFIG_STRICT_SIGALTSTACK_SIZE static bool strict_sigaltstack_size __ro_after_init = true; #else static bool strict_sigaltstack_size __ro_after_init = false; #endif static int __init strict_sas_size(char *arg) { return kstrtobool(arg, &strict_sigaltstack_size); } __setup("strict_sas_size", strict_sas_size); /* * MINSIGSTKSZ is 2048 and can't be changed despite the fact that AVX512 * exceeds that size already. As such programs might never use the * sigaltstack they just continued to work. While always checking against * the real size would be correct, this might be considered a regression. * * Therefore avoid the sanity check, unless enforced by kernel * configuration or command line option. * * When dynamic FPU features are supported, the check is also enforced when * the task has permissions to use dynamic features. Tasks which have no * permission are checked against the size of the non-dynamic feature set * if strict checking is enabled. This avoids forcing all tasks on the * system to allocate large sigaltstacks even if they are never going * to use a dynamic feature. As this is serialized via sighand::siglock * any permission request for a dynamic feature either happened already * or will see the newly install sigaltstack size in the permission checks. */ bool sigaltstack_size_valid(size_t ss_size) { unsigned long fsize = max_frame_size - fpu_default_state_size; u64 mask; lockdep_assert_held(¤t->sighand->siglock); if (!fpu_state_size_dynamic() && !strict_sigaltstack_size) return true; fsize += current->group_leader->thread.fpu.perm.__user_state_size; if (likely(ss_size > fsize)) return true; if (strict_sigaltstack_size) return ss_size > fsize; mask = current->group_leader->thread.fpu.perm.__state_perm; if (mask & XFEATURE_MASK_USER_DYNAMIC) return ss_size > fsize; return true; } #endif /* CONFIG_DYNAMIC_SIGFRAME */ #ifdef CONFIG_X86_X32_ABI COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn) { struct pt_regs *regs = current_pt_regs(); struct rt_sigframe_x32 __user *frame; sigset_t set; unsigned long uc_flags; frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8); if (!access_ok(frame, sizeof(*frame))) goto badframe; if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask)) goto badframe; if (__get_user(uc_flags, &frame->uc.uc_flags)) goto badframe; set_current_blocked(&set); if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) goto badframe; if (compat_restore_altstack(&frame->uc.uc_stack)) goto badframe; return regs->ax; badframe: signal_fault(regs, frame, "x32 rt_sigreturn"); return 0; } #endif