511 lines
15 KiB
C
511 lines
15 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/unistd.h>
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#include <linux/uaccess.h>
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#include <linux/syscalls.h>
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#include <asm/ucontext.h>
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#include <asm/fpu/signal.h>
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#include <asm/sighandling.h>
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#include <asm/syscall.h>
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#include <asm/sigframe.h>
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#include <asm/signal.h>
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/*
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* If regs->ss will cause an IRET fault, change it. Otherwise leave it
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* alone. Using this generally makes no sense unless
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* user_64bit_mode(regs) would return true.
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*/
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static void force_valid_ss(struct pt_regs *regs)
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{
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u32 ar;
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asm volatile ("lar %[old_ss], %[ar]\n\t"
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"jz 1f\n\t" /* If invalid: */
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"xorl %[ar], %[ar]\n\t" /* set ar = 0 */
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"1:"
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: [ar] "=r" (ar)
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: [old_ss] "rm" ((u16)regs->ss));
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/*
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* For a valid 64-bit user context, we need DPL 3, type
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* read-write data or read-write exp-down data, and S and P
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* set. We can't use VERW because VERW doesn't check the
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* P bit.
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*/
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ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
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if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
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ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
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regs->ss = __USER_DS;
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}
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static bool restore_sigcontext(struct pt_regs *regs,
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struct sigcontext __user *usc,
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unsigned long uc_flags)
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{
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struct sigcontext sc;
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/* Always make any pending restarted system calls return -EINTR */
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current->restart_block.fn = do_no_restart_syscall;
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if (copy_from_user(&sc, usc, offsetof(struct sigcontext, reserved1)))
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return false;
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regs->bx = sc.bx;
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regs->cx = sc.cx;
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regs->dx = sc.dx;
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regs->si = sc.si;
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regs->di = sc.di;
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regs->bp = sc.bp;
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regs->ax = sc.ax;
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regs->sp = sc.sp;
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regs->ip = sc.ip;
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regs->r8 = sc.r8;
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regs->r9 = sc.r9;
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regs->r10 = sc.r10;
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regs->r11 = sc.r11;
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regs->r12 = sc.r12;
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regs->r13 = sc.r13;
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regs->r14 = sc.r14;
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regs->r15 = sc.r15;
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/* Get CS/SS and force CPL3 */
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regs->cs = sc.cs | 0x03;
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regs->ss = sc.ss | 0x03;
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regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
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/* disable syscall checks */
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regs->orig_ax = -1;
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/*
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* Fix up SS if needed for the benefit of old DOSEMU and
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* CRIU.
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*/
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if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
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force_valid_ss(regs);
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return fpu__restore_sig((void __user *)sc.fpstate, 0);
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}
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static __always_inline int
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__unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
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struct pt_regs *regs, unsigned long mask)
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{
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unsafe_put_user(regs->di, &sc->di, Efault);
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unsafe_put_user(regs->si, &sc->si, Efault);
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unsafe_put_user(regs->bp, &sc->bp, Efault);
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unsafe_put_user(regs->sp, &sc->sp, Efault);
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unsafe_put_user(regs->bx, &sc->bx, Efault);
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unsafe_put_user(regs->dx, &sc->dx, Efault);
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unsafe_put_user(regs->cx, &sc->cx, Efault);
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unsafe_put_user(regs->ax, &sc->ax, Efault);
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unsafe_put_user(regs->r8, &sc->r8, Efault);
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unsafe_put_user(regs->r9, &sc->r9, Efault);
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unsafe_put_user(regs->r10, &sc->r10, Efault);
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unsafe_put_user(regs->r11, &sc->r11, Efault);
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unsafe_put_user(regs->r12, &sc->r12, Efault);
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unsafe_put_user(regs->r13, &sc->r13, Efault);
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unsafe_put_user(regs->r14, &sc->r14, Efault);
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unsafe_put_user(regs->r15, &sc->r15, Efault);
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unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
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unsafe_put_user(current->thread.error_code, &sc->err, Efault);
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unsafe_put_user(regs->ip, &sc->ip, Efault);
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unsafe_put_user(regs->flags, &sc->flags, Efault);
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unsafe_put_user(regs->cs, &sc->cs, Efault);
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unsafe_put_user(0, &sc->gs, Efault);
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unsafe_put_user(0, &sc->fs, Efault);
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unsafe_put_user(regs->ss, &sc->ss, Efault);
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unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault);
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/* non-iBCS2 extensions.. */
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unsafe_put_user(mask, &sc->oldmask, Efault);
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unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
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return 0;
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Efault:
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return -EFAULT;
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}
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#define unsafe_put_sigcontext(sc, fp, regs, set, label) \
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do { \
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if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \
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goto label; \
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} while(0);
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#define unsafe_put_sigmask(set, frame, label) \
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unsafe_put_user(*(__u64 *)(set), \
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(__u64 __user *)&(frame)->uc.uc_sigmask, \
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label)
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static unsigned long frame_uc_flags(struct pt_regs *regs)
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{
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unsigned long flags;
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if (boot_cpu_has(X86_FEATURE_XSAVE))
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flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
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else
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flags = UC_SIGCONTEXT_SS;
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if (likely(user_64bit_mode(regs)))
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flags |= UC_STRICT_RESTORE_SS;
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return flags;
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}
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int x64_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
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{
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sigset_t *set = sigmask_to_save();
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struct rt_sigframe __user *frame;
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void __user *fp = NULL;
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unsigned long uc_flags;
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/* x86-64 should always use SA_RESTORER. */
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if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
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return -EFAULT;
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frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe), &fp);
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uc_flags = frame_uc_flags(regs);
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if (!user_access_begin(frame, sizeof(*frame)))
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return -EFAULT;
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/* Create the ucontext. */
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unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
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unsafe_put_user(0, &frame->uc.uc_link, Efault);
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unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
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/* Set up to return from userspace. If provided, use a stub
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already in userspace. */
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unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
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unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
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unsafe_put_sigmask(set, frame, Efault);
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user_access_end();
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if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
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if (copy_siginfo_to_user(&frame->info, &ksig->info))
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return -EFAULT;
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}
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/* Set up registers for signal handler */
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regs->di = ksig->sig;
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/* In case the signal handler was declared without prototypes */
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regs->ax = 0;
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/* This also works for non SA_SIGINFO handlers because they expect the
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next argument after the signal number on the stack. */
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regs->si = (unsigned long)&frame->info;
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regs->dx = (unsigned long)&frame->uc;
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regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
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regs->sp = (unsigned long)frame;
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/*
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* Set up the CS and SS registers to run signal handlers in
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* 64-bit mode, even if the handler happens to be interrupting
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* 32-bit or 16-bit code.
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*
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* SS is subtle. In 64-bit mode, we don't need any particular
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* SS descriptor, but we do need SS to be valid. It's possible
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* that the old SS is entirely bogus -- this can happen if the
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* signal we're trying to deliver is #GP or #SS caused by a bad
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* SS value. We also have a compatibility issue here: DOSEMU
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* relies on the contents of the SS register indicating the
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* SS value at the time of the signal, even though that code in
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* DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
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* avoids relying on sigreturn to restore SS; instead it uses
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* a trampoline.) So we do our best: if the old SS was valid,
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* we keep it. Otherwise we replace it.
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*/
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regs->cs = __USER_CS;
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if (unlikely(regs->ss != __USER_DS))
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force_valid_ss(regs);
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return 0;
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Efault:
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user_access_end();
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return -EFAULT;
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}
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/*
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* Do a signal return; undo the signal stack.
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*/
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SYSCALL_DEFINE0(rt_sigreturn)
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{
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struct pt_regs *regs = current_pt_regs();
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struct rt_sigframe __user *frame;
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sigset_t set;
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unsigned long uc_flags;
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frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
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if (!access_ok(frame, sizeof(*frame)))
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goto badframe;
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if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
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goto badframe;
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if (__get_user(uc_flags, &frame->uc.uc_flags))
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goto badframe;
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set_current_blocked(&set);
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if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
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goto badframe;
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if (restore_altstack(&frame->uc.uc_stack))
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goto badframe;
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return regs->ax;
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badframe:
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signal_fault(regs, frame, "rt_sigreturn");
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return 0;
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}
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#ifdef CONFIG_X86_X32_ABI
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static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
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const struct kernel_siginfo *from)
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{
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struct compat_siginfo new;
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copy_siginfo_to_external32(&new, from);
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if (from->si_signo == SIGCHLD) {
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new._sifields._sigchld_x32._utime = from->si_utime;
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new._sifields._sigchld_x32._stime = from->si_stime;
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}
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if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
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return -EFAULT;
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return 0;
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}
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int copy_siginfo_to_user32(struct compat_siginfo __user *to,
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const struct kernel_siginfo *from)
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{
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if (in_x32_syscall())
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return x32_copy_siginfo_to_user(to, from);
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return __copy_siginfo_to_user32(to, from);
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}
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int x32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
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{
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compat_sigset_t *set = (compat_sigset_t *) sigmask_to_save();
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struct rt_sigframe_x32 __user *frame;
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unsigned long uc_flags;
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void __user *restorer;
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void __user *fp = NULL;
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if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
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return -EFAULT;
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frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
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uc_flags = frame_uc_flags(regs);
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if (!user_access_begin(frame, sizeof(*frame)))
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return -EFAULT;
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/* Create the ucontext. */
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unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
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unsafe_put_user(0, &frame->uc.uc_link, Efault);
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unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
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unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
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restorer = ksig->ka.sa.sa_restorer;
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unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
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unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
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unsafe_put_sigmask(set, frame, Efault);
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user_access_end();
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if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
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if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
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return -EFAULT;
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}
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/* Set up registers for signal handler */
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regs->sp = (unsigned long) frame;
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regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
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/* We use the x32 calling convention here... */
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regs->di = ksig->sig;
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regs->si = (unsigned long) &frame->info;
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regs->dx = (unsigned long) &frame->uc;
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loadsegment(ds, __USER_DS);
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loadsegment(es, __USER_DS);
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regs->cs = __USER_CS;
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regs->ss = __USER_DS;
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return 0;
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Efault:
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user_access_end();
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return -EFAULT;
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}
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COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
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{
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struct pt_regs *regs = current_pt_regs();
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struct rt_sigframe_x32 __user *frame;
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sigset_t set;
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unsigned long uc_flags;
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frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
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if (!access_ok(frame, sizeof(*frame)))
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goto badframe;
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if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
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goto badframe;
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if (__get_user(uc_flags, &frame->uc.uc_flags))
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goto badframe;
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set_current_blocked(&set);
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if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
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goto badframe;
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if (compat_restore_altstack(&frame->uc.uc_stack))
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goto badframe;
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return regs->ax;
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badframe:
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signal_fault(regs, frame, "x32 rt_sigreturn");
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return 0;
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}
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#endif /* CONFIG_X86_X32_ABI */
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#ifdef CONFIG_COMPAT
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void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact)
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{
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if (!act)
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return;
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if (in_ia32_syscall())
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act->sa.sa_flags |= SA_IA32_ABI;
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if (in_x32_syscall())
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act->sa.sa_flags |= SA_X32_ABI;
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}
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#endif /* CONFIG_COMPAT */
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/*
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* If adding a new si_code, there is probably new data in
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* the siginfo. Make sure folks bumping the si_code
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* limits also have to look at this code. Make sure any
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* new fields are handled in copy_siginfo_to_user32()!
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*/
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static_assert(NSIGILL == 11);
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static_assert(NSIGFPE == 15);
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static_assert(NSIGSEGV == 9);
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static_assert(NSIGBUS == 5);
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static_assert(NSIGTRAP == 6);
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static_assert(NSIGCHLD == 6);
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static_assert(NSIGSYS == 2);
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/* This is part of the ABI and can never change in size: */
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static_assert(sizeof(siginfo_t) == 128);
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/* This is a part of the ABI and can never change in alignment */
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static_assert(__alignof__(siginfo_t) == 8);
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/*
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* The offsets of all the (unioned) si_fields are fixed
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* in the ABI, of course. Make sure none of them ever
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* move and are always at the beginning:
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*/
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static_assert(offsetof(siginfo_t, si_signo) == 0);
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static_assert(offsetof(siginfo_t, si_errno) == 4);
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static_assert(offsetof(siginfo_t, si_code) == 8);
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/*
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* Ensure that the size of each si_field never changes.
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* If it does, it is a sign that the
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* copy_siginfo_to_user32() code below needs to updated
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* along with the size in the CHECK_SI_SIZE().
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*
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* We repeat this check for both the generic and compat
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* siginfos.
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*
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* Note: it is OK for these to grow as long as the whole
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* structure stays within the padding size (checked
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* above).
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*/
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#define CHECK_SI_OFFSET(name) \
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static_assert(offsetof(siginfo_t, _sifields) == \
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offsetof(siginfo_t, _sifields.name))
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#define CHECK_SI_SIZE(name, size) \
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static_assert(sizeof_field(siginfo_t, _sifields.name) == size)
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CHECK_SI_OFFSET(_kill);
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CHECK_SI_SIZE (_kill, 2*sizeof(int));
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static_assert(offsetof(siginfo_t, si_pid) == 0x10);
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static_assert(offsetof(siginfo_t, si_uid) == 0x14);
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CHECK_SI_OFFSET(_timer);
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CHECK_SI_SIZE (_timer, 6*sizeof(int));
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static_assert(offsetof(siginfo_t, si_tid) == 0x10);
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static_assert(offsetof(siginfo_t, si_overrun) == 0x14);
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static_assert(offsetof(siginfo_t, si_value) == 0x18);
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CHECK_SI_OFFSET(_rt);
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CHECK_SI_SIZE (_rt, 4*sizeof(int));
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static_assert(offsetof(siginfo_t, si_pid) == 0x10);
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static_assert(offsetof(siginfo_t, si_uid) == 0x14);
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static_assert(offsetof(siginfo_t, si_value) == 0x18);
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CHECK_SI_OFFSET(_sigchld);
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CHECK_SI_SIZE (_sigchld, 8*sizeof(int));
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static_assert(offsetof(siginfo_t, si_pid) == 0x10);
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static_assert(offsetof(siginfo_t, si_uid) == 0x14);
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static_assert(offsetof(siginfo_t, si_status) == 0x18);
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static_assert(offsetof(siginfo_t, si_utime) == 0x20);
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static_assert(offsetof(siginfo_t, si_stime) == 0x28);
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#ifdef CONFIG_X86_X32_ABI
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/* no _sigchld_x32 in the generic siginfo_t */
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static_assert(sizeof_field(compat_siginfo_t, _sifields._sigchld_x32) ==
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7*sizeof(int));
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static_assert(offsetof(compat_siginfo_t, _sifields) ==
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offsetof(compat_siginfo_t, _sifields._sigchld_x32));
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static_assert(offsetof(compat_siginfo_t, _sifields._sigchld_x32._utime) == 0x18);
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static_assert(offsetof(compat_siginfo_t, _sifields._sigchld_x32._stime) == 0x20);
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#endif
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CHECK_SI_OFFSET(_sigfault);
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CHECK_SI_SIZE (_sigfault, 8*sizeof(int));
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static_assert(offsetof(siginfo_t, si_addr) == 0x10);
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static_assert(offsetof(siginfo_t, si_trapno) == 0x18);
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static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x18);
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static_assert(offsetof(siginfo_t, si_lower) == 0x20);
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static_assert(offsetof(siginfo_t, si_upper) == 0x28);
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static_assert(offsetof(siginfo_t, si_pkey) == 0x20);
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static_assert(offsetof(siginfo_t, si_perf_data) == 0x18);
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static_assert(offsetof(siginfo_t, si_perf_type) == 0x20);
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static_assert(offsetof(siginfo_t, si_perf_flags) == 0x24);
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CHECK_SI_OFFSET(_sigpoll);
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CHECK_SI_SIZE (_sigpoll, 4*sizeof(int));
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static_assert(offsetof(siginfo_t, si_band) == 0x10);
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static_assert(offsetof(siginfo_t, si_fd) == 0x18);
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CHECK_SI_OFFSET(_sigsys);
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CHECK_SI_SIZE (_sigsys, 4*sizeof(int));
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static_assert(offsetof(siginfo_t, si_call_addr) == 0x10);
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static_assert(offsetof(siginfo_t, si_syscall) == 0x18);
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static_assert(offsetof(siginfo_t, si_arch) == 0x1C);
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/* any new si_fields should be added here */
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