72 lines
2.2 KiB
Go
72 lines
2.2 KiB
Go
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// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: BSD-3-Clause
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//go:build amd64 || arm64 || riscv64 || loong64
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package verify
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import (
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"encoding/binary"
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"fmt"
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"syscall"
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"unsafe"
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)
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// CallChecked invokes the function at fnAddr with ABI sentinels and a
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// canary below SP, returning both the argument block (with results) and an
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// ABIReport.
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//
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// The architecture-specific parts live in abi_<arch>.s: enterJITChecked
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// plants sentinels in the registers the Go ABI fixes across calls (the
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// frame pointer and the goroutine pointer) before switching to the
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// prepared stack, and the raw return trampoline leaveJITCheckedRaw
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// compares them and records violations in abiResult.
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func CallChecked(fnAddr uintptr, args []byte) ([]byte, ABIReport, error) {
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report := ABIReport{}
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// Reset the global result.
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abiResult = 0
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// Prepare the stack: [canary][padding][leaveJITCheckedRaw][args...]
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// The canary sits below the initial SP, so the function would have to
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// write below SP to corrupt it.
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totalSize := redZoneSize + stackPad + 8 + len(args) + 64
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stackMem, err := syscall.Mmap(-1, 0, totalSize,
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syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_PRIVATE|syscall.MAP_ANON)
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if err != nil {
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return nil, report, fmt.Errorf("verify: stack mmap: %w", err)
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}
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defer func() { _ = syscall.Munmap(stackMem) }()
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// Fill the canary window with the detection pattern.
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for i := range redZoneSize {
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stackMem[i] = redZoneFill
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}
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// Return address and args after the canary and padding.
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retOff := redZoneSize + stackPad
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binary.LittleEndian.PutUint64(stackMem[retOff:retOff+8], uint64(leaveCheckedPtr))
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copy(stackMem[retOff+8:], args)
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stackBase := uintptr(unsafe.Pointer(&stackMem[retOff]))
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enterJITChecked(fnAddr, stackBase)
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// Read the register-clobber result.
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res := abiResult
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report.FPClobbered = res&1 != 0
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report.GClobbered = res&2 != 0
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// Check the canary window.
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for i := range redZoneSize {
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if stackMem[i] != redZoneFill {
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report.RedZoneHit = true
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break
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}
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}
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// Copy out the argument area.
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out := make([]byte, len(args))
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copy(out, stackMem[retOff+8:retOff+8+len(args)])
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return out, report, nil
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}
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