42 lines
1.5 KiB
Go
42 lines
1.5 KiB
Go
//go:build amd64 && gc && !purego
|
|
|
|
/* SPDX-License-Identifier: MIT
|
|
*
|
|
* Copyright (C) 2017-2023 WireGuard LLC. All Rights Reserved.
|
|
*/
|
|
|
|
package device
|
|
|
|
import (
|
|
"crypto/cipher"
|
|
"os"
|
|
|
|
"golang.org/x/crypto/chacha20poly1305"
|
|
"golang.org/x/sys/cpu"
|
|
|
|
asmAEAD "github.com/tailscale/wireguard-go/tsasm/amd64/chacha20poly1305"
|
|
)
|
|
|
|
/*
|
|
shouldUseTSAsm reports whether the data-path AEAD should come from tsasm/amd64. x/crypto gates its remaining amd64 kernel on HasSSSE3 && HasAVX2 && HasBMI2 and otherwise runs generic Go, so only CPUs with SSSE3 and no AVX2 are routed here. Pure so a test can cover every combination; the CPU variables cannot be written.
|
|
*/
|
|
func shouldUseTSAsm(hasSSSE3, hasAVX2, hasBMI2 bool) bool {
|
|
return hasSSSE3 && !(hasAVX2 && hasBMI2)
|
|
}
|
|
|
|
var useTSAsm = shouldUseTSAsm(asmAEAD.Available(), cpu.X86.HasAVX2, cpu.X86.HasBMI2)
|
|
|
|
/*
|
|
chacha20poly1305New returns a ChaCha20-Poly1305 AEAD. On amd64 CPUs with SSSE3 but no AVX2 it uses the assembly kernel from tsasm/amd64/chacha20poly1305.
|
|
|
|
The cookie path (which uses the extended-nonce variant via chacha20poly1305.NewX) is left on the x/crypto path because it is not on the per-packet hot path.
|
|
|
|
As an escape hatch for hardware regressions or asm bugs, setting the environment variable TS_WG_ASM=0 forces the x/crypto implementation instead.
|
|
*/
|
|
func chacha20poly1305New(key []byte) (cipher.AEAD, error) {
|
|
if !useTSAsm || os.Getenv("TS_WG_ASM") == "0" {
|
|
return chacha20poly1305.New(key)
|
|
}
|
|
return asmAEAD.New(key)
|
|
}
|