personal_interest_mirrors/nebula
1
0
Fork 0
mirror of https://github.com/slackhq/nebula.git synced 2026-08-15 12:16:59 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

decrypt in place

Browse Source
This commit is contained in:
JackDoan
2026-07-15 09:16:40 -05:00
parent c6ebe71c08
commit ef0e3015f9
16 changed files with 183 additions and 263 deletions
Download Patch File Download Diff File Expand all files Collapse all files
outside.go
+41 -14
View File
@@ -23,7 +23,10 @@ const (
var ErrOutOfWindow = errors.New("out of window packet")
func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache, meta udp.RxMeta) {
// readOutsidePackets processes one received underlay packet.
// Message payloads are decrypted IN PLACE, so packet must stay untouched
// by the caller until the batcher for queue q has been flushed
func (f *Interface) readOutsidePackets(via ViaSender, scratch []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache, meta udp.RxMeta) {
err := h.Parse(packet)
if err != nil {
// Hole punch packets are 0 or 1 byte big, so lets ignore printing those errors
@@ -120,11 +123,11 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
}
return
}
f.handleOutsideRelayPacket(hostinfo, via, out, packet, h, fwPacket, lhf, nb, q, localCache, meta)
f.handleOutsideRelayPacket(hostinfo, via, scratch, packet, h, fwPacket, lhf, nb, q, localCache, meta)
return
}
out, err = hostinfo.ConnectionState.Decrypt(f.l, h.MessageCounter, out, packet, nb)
out, err := hostinfo.ConnectionState.Decrypt(f.l, h.MessageCounter, packet, nb)
if err != nil {
if f.l.Enabled(context.Background(), slog.LevelDebug) {
hostinfo.logger(f.l).Debug("Failed to decrypt packet", "error", err, "from", via, "header", h)
@@ -140,7 +143,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
case header.Message:
switch h.Subtype {
case header.MessageNone:
f.handleOutsideMessagePacket(hostinfo, out, packet, fwPacket, nb, q, localCache, meta)
f.handleOutsideMessagePacket(hostinfo, out, scratch, fwPacket, nb, q, localCache, meta)
default:
hostinfo.logger(f.l).Error("IsValidSubType was true, but unexpected message subtype seen", "from", via, "header", h)
return
@@ -155,8 +158,15 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
case header.TestReply:
// No-op, useful for the Roaming and connectionManager side-effects above
case header.TestRequest:
//recycle the input packet ciphertext as our output buffer
f.send(header.Test, header.TestReply, hostinfo.ConnectionState, hostinfo, out, nb, packet)
const maxCipherOverhead = 16 //todo we use this too often, needs a real importable const
const maxOverhead = header.Len + header.Len + maxCipherOverhead + maxCipherOverhead
if maxOverhead+len(out) <= len(scratch) {
f.send(header.Test, header.TestReply, hostinfo.ConnectionState, hostinfo, out, nb, scratch[:0])
return
} else if f.l.Enabled(context.Background(), slog.LevelDebug) {
hostinfo.logger(f.l).Debug("dropping oversized test request", "payloadLen", len(out), "from", via)
return
}
default:
hostinfo.logger(f.l).Error("IsValidSubType was true, but unexpected test subtype seen", "from", via, "header", h)
return
@@ -174,7 +184,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
}
}
func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender, out []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache, meta udp.RxMeta) {
func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender, scratch []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache, meta udp.RxMeta) {
// Successfully validated the thing. Get rid of the Relay header and the AEAD tag
signedPayload := packet[header.Len : len(packet)-hostinfo.ConnectionState.dKey.Overhead()]
// Pull the Roaming parts up here, and return in all call paths.
@@ -203,7 +213,7 @@ func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender,
relay: relay,
IsRelayed: true,
}
f.readOutsidePackets(via, out[:0], signedPayload, h, fwPacket, lhf, nb, q, localCache, meta)
f.readOutsidePackets(via, scratch, signedPayload, h, fwPacket, lhf, nb, q, localCache, meta)
case ForwardingType:
// Find the target HostInfo relay object
targetHI, targetRelay, err := f.hostMap.QueryVpnAddrsRelayFor(hostinfo.vpnAddrs, relay.PeerAddr)
@@ -491,6 +501,27 @@ func parseV4(data []byte, incoming bool, fp *firewall.Packet) error {
return nil
}
// decrypt authenticates and decrypts a Message packet IN PLACE: the dst is
// packet[header.Len:header.Len], the exact-alias append pattern
// (ciphertext[:0]) that crypto/cipher.AEAD.Open documents, so the plaintext
// lands where the ciphertext sat and no separate plaintext buffer exists.
// On a failed auth the AEAD zeroes the would-be plaintext region (both
// AES-GCM and ChaCha20-Poly1305 do) but never writes outside it, so the
// other segments of a shared GRO receive row stay intact; nothing reads a
// packet after its decrypt fails. The returned slice aliases packet.
func (f *Interface) decrypt(hostinfo *HostInfo, mc uint64, packet []byte, nb []byte) ([]byte, error) {
out, err := hostinfo.ConnectionState.dKey.DecryptDanger(packet[header.Len:header.Len], packet[:header.Len], packet[header.Len:], mc, nb)
if err != nil {
return nil, err
}
if !hostinfo.ConnectionState.window.Update(f.l, mc) {
return nil, ErrOutOfWindow
}
return out, nil
}
// 2-bit IP-level ECN codepoints (lower bits of IPv4 ToS / IPv6 TC).
const (
ecnNotECT = 0x00
@@ -554,7 +585,7 @@ func applyOuterECN(pkt []byte, outerECN byte, hostinfo *HostInfo, l *slog.Logger
}
}
func (f *Interface) handleOutsideMessagePacket(hostinfo *HostInfo, out []byte, packet []byte, fwPacket *firewall.Packet, nb []byte, q int, localCache firewall.ConntrackCache, meta udp.RxMeta) {
func (f *Interface) handleOutsideMessagePacket(hostinfo *HostInfo, out []byte, scratch []byte, fwPacket *firewall.Packet, nb []byte, q int, localCache firewall.ConntrackCache, meta udp.RxMeta) {
// RFC 6040 normal-mode combine: fold any outer CE mark stamped by the
// underlay into the inner header before firewall + TUN write. Other
// outer codepoints are advisory only — we keep the inner unchanged.
@@ -573,11 +604,7 @@ func (f *Interface) handleOutsideMessagePacket(hostinfo *HostInfo, out []byte, p
dropReason := f.firewall.Drop(*fwPacket, true, hostinfo, f.pki.GetCAPool(), localCache)
if dropReason != nil {
// NOTE: We give `packet` as the `out` here since we already decrypted from it and we don't need it anymore
// This gives us a buffer to build the reject packet in. With UDP GRO this is a single segment of a shared
// recvmmsg row whose capacity runs to the end of the whole row, so cap it to its own length (cap==len) to
// keep the reject builder from writing past this segment into the next, not-yet-processed coalesced segment.
f.rejectOutside(out, hostinfo.ConnectionState, hostinfo, nb, packet[:len(packet):len(packet)], q)
f.rejectOutside(out, hostinfo.ConnectionState, hostinfo, nb, scratch, q)
if f.l.Enabled(context.Background(), slog.LevelDebug) {
hostinfo.logger(f.l).Debug("dropping inbound packet",
"fwPacket", fwPacket,