From eb6302c7eb71e3e3df9f63395bc5c97dcf0efc84 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Thu, 28 Oct 2021 13:47:50 +0200 Subject: device: timers: use pre-seeded per-thread unlocked fastrandn for jitter Signed-off-by: Jason A. Donenfeld --- device/timers.go | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/device/timers.go b/device/timers.go index aa6f28a..176976d 100644 --- a/device/timers.go +++ b/device/timers.go @@ -8,19 +8,14 @@ package device import ( - "crypto/rand" - unsafeRand "math/rand" "sync" "sync/atomic" "time" - "unsafe" + _ "unsafe" ) -func init() { - var seed int64 - rand.Read(unsafe.Slice((*byte)(unsafe.Pointer(&seed)), unsafe.Sizeof(seed))) - unsafeRand.Seed(seed) -} +//go:linkname fastrandn runtime.fastrandn +func fastrandn(n uint32) uint32 // A Timer manages time-based aspects of the WireGuard protocol. // Timer roughly copies the interface of the Linux kernel's struct timer_list. @@ -152,7 +147,7 @@ func expiredPersistentKeepalive(peer *Peer) { /* Should be called after an authenticated data packet is sent. */ func (peer *Peer) timersDataSent() { if peer.timersActive() && !peer.timers.newHandshake.IsPending() { - peer.timers.newHandshake.Mod(KeepaliveTimeout + RekeyTimeout + time.Millisecond*time.Duration(unsafeRand.Int63n(RekeyTimeoutJitterMaxMs))) + peer.timers.newHandshake.Mod(KeepaliveTimeout + RekeyTimeout + time.Millisecond*time.Duration(fastrandn(RekeyTimeoutJitterMaxMs))) } } @@ -184,7 +179,7 @@ func (peer *Peer) timersAnyAuthenticatedPacketReceived() { /* Should be called after a handshake initiation message is sent. */ func (peer *Peer) timersHandshakeInitiated() { if peer.timersActive() { - peer.timers.retransmitHandshake.Mod(RekeyTimeout + time.Millisecond*time.Duration(unsafeRand.Int63n(RekeyTimeoutJitterMaxMs))) + peer.timers.retransmitHandshake.Mod(RekeyTimeout + time.Millisecond*time.Duration(fastrandn(RekeyTimeoutJitterMaxMs))) } } -- cgit v1.2.3