remove AEAD-UDP nonce replay check

Author: zonyitoo

Cargo.toml

@@ -129,7 +129,7 @@ aead-cipher-extra = ["shadowsocks-service/aead-cipher-extra"]
 # Enable AEAD 2022
 aead-cipher-2022 = ["shadowsocks-service/aead-cipher-2022"]
 
-# Enable detection against replay attack
+# Enable detection against replay attack (Stream / AEAD)
 security-replay-attack-detect = ["shadowsocks-service/security-replay-attack-detect"]
 replay-attack-detect = ["security-replay-attack-detect"] # Backward compatibility. DO NOT USE.
 # Enable IV printable prefix

crates/shadowsocks-service/src/local/loadbalancing/ping_balancer.rs

@@ -23,7 +23,7 @@ use shadowsocks::{
     relay::{
         socks5::Address,
         tcprelay::proxy_stream::ProxyClientStream,
-        udprelay::{proxy_socket::ProxySocket, MAXIMUM_UDP_PAYLOAD_SIZE},
+        udprelay::{options::UdpSocketControlData, proxy_socket::ProxySocket, MAXIMUM_UDP_PAYLOAD_SIZE},
     },
     ServerConfig,
 };
@@ -882,7 +882,13 @@ impl PingChecker {
             self.context.connect_opts_ref(),
         )
         .await?;
-        client.send(&addr, DNS_QUERY).await?;
+
+        let control = UdpSocketControlData {
+            client_session_id: rand::random::<u64>(),
+            server_session_id: 0,
+            packet_id: 1,
+        };
+        client.send_with_ctrl(&addr, &control, DNS_QUERY).await?;
 
         let mut buffer = [0u8; MAXIMUM_UDP_PAYLOAD_SIZE];
         let (n, ..) = client.recv(&mut buffer).await?;

crates/shadowsocks-service/src/server/udprelay.rs

@@ -313,31 +313,16 @@ impl UdpAssociation {
     }
 }
 
-struct ClientContext {
-    packet_window_filter: PacketWindowFilter,
-}
-
 struct ClientSessionContext {
     client_session_id: u64,
-    client_context_map: LruCache<SocketAddr, ClientContext>,
+    packet_window_filter: PacketWindowFilter,
 }
 
 impl ClientSessionContext {
     fn new(client_session_id: u64) -> ClientSessionContext {
-        // Client shouldn't be remembered too long.
-        // If a client was switching between networks (like Wi-Fi and Cellular),
-        // when it switched back from another, the packet filter window will be too old.
-        const CLIENT_SESSION_REMEMBER_DURATION: Duration = Duration::from_secs(60);
-
-        // Wi-Fi & Cellular network device, so it is 2 for most users
-        const CLIENT_SESSION_REMEMBER_COUNT: usize = 2;
-
         ClientSessionContext {
             client_session_id,
-            client_context_map: LruCache::with_expiry_duration_and_capacity(
-                CLIENT_SESSION_REMEMBER_DURATION,
-                CLIENT_SESSION_REMEMBER_COUNT,
-            ),
+            packet_window_filter: PacketWindowFilter::new(),
         }
     }
 }
@@ -524,21 +509,10 @@ impl UdpAssociationContext {
         if let Some(control) = control {
             // Check if Packet ID is in the window
 
-            let session = self
+            let session_context = self
                 .client_session
                 .get_or_insert_with(|| ClientSessionContext::new(control.client_session_id));
 
-            let session_context = session.client_context_map.entry(self.peer_addr).or_insert_with(|| {
-                trace!(
-                    "udp client {} with session {} created",
-                    self.peer_addr,
-                    control.client_session_id
-                );
-                ClientContext {
-                    packet_window_filter: PacketWindowFilter::new(),
-                }
-            });
-
             let packet_id = control.packet_id;
             if !session_context
                 .packet_window_filter

crates/shadowsocks/Cargo.toml

@@ -32,10 +32,10 @@ stream-cipher = ["shadowsocks-crypto/v1-stream"]
 aead-cipher-extra = ["shadowsocks-crypto/v1-aead-extra"]
 
 # Enable AEAD 2022
-aead-cipher-2022 = ["shadowsocks-crypto/v2", "rand/small_rng", "aes", "lru_time_cache", "spin"]
+aead-cipher-2022 = ["shadowsocks-crypto/v2", "rand/small_rng", "aes", "lru_time_cache"]
 
 # Enable detection against replay attack
-security-replay-attack-detect = ["bloomfilter", "spin"]
+security-replay-attack-detect = ["bloomfilter"]
 # Enable IV printable prefix
 security-iv-printable-prefix = ["rand"]
 
@@ -54,7 +54,7 @@ byte_string = "1.0"
 base64 = "0.13"
 url = "2.2"
 once_cell = "1.8"
-spin = { version = "0.9", features = ["std"], optional = true }
+spin = { version = "0.9", features = ["std"] }
 pin-project = "1.0"
 bloomfilter = { version = "1.0.8", optional = true }
 thiserror = "1.0"

crates/shadowsocks/src/context.rs

@@ -35,7 +35,7 @@ impl Context {
     pub fn new(config_type: ServerType) -> Context {
         Context {
             replay_protector: ReplayProtector::new(config_type),
-            replay_policy: ReplayAttackPolicy::Ignore,
+            replay_policy: ReplayAttackPolicy::Reject,
             dns_resolver: Arc::new(DnsResolver::system_resolver()),
             ipv6_first: false,
         }

crates/shadowsocks/src/relay/udprelay/aead_2022.rs

@@ -63,13 +63,10 @@ use aes::{
 };
 use byte_string::ByteStr;
 use bytes::{Buf, BufMut, BytesMut};
-use log::{error, trace, warn};
+use log::trace;
 use lru_time_cache::LruCache;
-use once_cell::sync::Lazy;
-use spin::Mutex as SpinMutex;
 
 use crate::{
-    config::ReplayAttackPolicy,
     context::Context,
     crypto::{
         v2::udp::{ChaCha20Poly1305Cipher, UdpCipher},
@@ -159,57 +156,6 @@ fn get_cipher(method: CipherKind, key: &[u8], session_id: u64) -> Rc<UdpCipher>
     })
 }
 
-fn check_and_record_nonce(method: CipherKind, key: &[u8], session_id: u64, nonce: &[u8]) -> bool {
-    static REPLAY_FILTER_RECORDER: Lazy<SpinMutex<LruCache<CipherKey, LruCache<Vec<u8>, ()>>>> = Lazy::new(|| {
-        SpinMutex::new(LruCache::with_expiry_duration_and_capacity(
-            CIPHER_CACHE_DURATION,
-            CIPHER_CACHE_LIMIT,
-        ))
-    });
-
-    let cache_key = CipherKey {
-        method,
-        // The key is stored in ServerConfig structure, so the address of it won't change.
-        key: key.as_ptr() as usize,
-        session_id,
-    };
-
-    const REPLAY_DETECT_NONCE_EXPIRE_DURATION: Duration = Duration::from_secs(SERVER_PACKET_TIMESTAMP_MAX_DIFF);
-
-    let mut session_map = REPLAY_FILTER_RECORDER.lock();
-
-    let session_nonce_map = session_map
-        .entry(cache_key)
-        .or_insert_with(|| LruCache::with_expiry_duration(REPLAY_DETECT_NONCE_EXPIRE_DURATION));
-
-    if session_nonce_map.get(nonce).is_some() {
-        return true;
-    }
-
-    session_nonce_map.insert(nonce.to_vec(), ());
-    false
-}
-
-#[inline]
-fn check_nonce_replay(context: &Context, method: CipherKind, key: &[u8], session_id: u64, nonce: &[u8]) -> bool {
-    match context.replay_attack_policy() {
-        ReplayAttackPolicy::Ignore => false,
-        ReplayAttackPolicy::Detect => {
-            if check_and_record_nonce(method, key, session_id, nonce) {
-                warn!("detected repeated nonce salt {:?}", ByteStr::new(nonce));
-            }
-            false
-        }
-        ReplayAttackPolicy::Reject => {
-            let replayed = check_and_record_nonce(method, key, session_id, nonce);
-            if replayed {
-                error!("detected repeated nonce salt {:?}", ByteStr::new(nonce));
-            }
-            replayed
-        }
-    }
-}
-
 fn encrypt_message(_context: &Context, method: CipherKind, key: &[u8], packet: &mut BytesMut, session_id: u64) {
     unsafe {
         packet.advance_mut(method.tag_len());
@@ -255,7 +201,7 @@ fn encrypt_message(_context: &Context, method: CipherKind, key: &[u8], packet: &
     }
 }
 
-fn decrypt_message(context: &Context, method: CipherKind, key: &[u8], packet: &mut [u8]) -> bool {
+fn decrypt_message(_context: &Context, method: CipherKind, key: &[u8], packet: &mut [u8]) -> bool {
     match method {
         CipherKind::AEAD2022_BLAKE3_CHACHA20_POLY1305 => {
             // ChaCha20-Poly1305 uses PSK as key, prepended nonce in packet
@@ -272,11 +218,6 @@ fn decrypt_message(context: &Context, method: CipherKind, key: &[u8], packet: &m
                 u64::from_be(session_id_slice[0])
             };
 
-            if check_nonce_replay(context, method, key, session_id, nonce) {
-                error!("detected replayed nonce: {:?}", ByteStr::new(nonce));
-                return false;
-            }
-
             let cipher = get_cipher(method, key, session_id);
 
             if !cipher.decrypt_packet(nonce, message) {
@@ -316,14 +257,7 @@ fn decrypt_message(context: &Context, method: CipherKind, key: &[u8], packet: &m
 
             let nonce = &packet_header[4..16];
 
-            let cipher = {
-                if check_nonce_replay(context, method, key, session_id, nonce) {
-                    error!("detected replayed nonce: {:?}", ByteStr::new(nonce));
-                    return false;
-                }
-
-                get_cipher(method, key, session_id)
-            };
+            let cipher = get_cipher(method, key, session_id);
 
             if !cipher.decrypt_packet(nonce, message) {
                 return false;

crates/shadowsocks/src/security/replay/dummy.rs

@@ -1,11 +1,76 @@
+#[cfg(feature = "aead-cipher-2022")]
+use std::time::Duration;
+
 use cfg_if::cfg_if;
+#[cfg(feature = "aead-cipher-2022")]
+use lru_time_cache::LruCache;
+#[allow(dead_code)]
+use spin::Mutex as SpinMutex;
+
+#[cfg(feature = "aead-cipher-2022")]
+use crate::relay::tcprelay::proxy_stream::protocol::v2::SERVER_STREAM_TIMESTAMP_MAX_DIFF;
+use crate::{config::ServerType, crypto::CipherKind};
+
+#[cfg(feature = "security-replay-attack-detect")]
+use self::ppbloom::PingPongBloom;
+
+#[cfg(feature = "security-replay-attack-detect")]
+mod ppbloom;
+
+/// A Bloom Filter based protector against replay attach
+pub struct ReplayProtector {
+    // Check for duplicated IV/Nonce, for prevent replay attack
+    // https://github.com/shadowsocks/shadowsocks-org/issues/44
+    #[cfg(feature = "security-replay-attack-detect")]
+    nonce_ppbloom: SpinMutex<PingPongBloom>,
+
+    // AEAD 2022 specific filter.
+    // AEAD 2022 TCP protocol has a timestamp, which can already reject most of the replay requests,
+    // so we only need to remember nonce that are in the valid time range
+    #[cfg(feature = "aead-cipher-2022")]
+    nonce_set: SpinMutex<LruCache<Vec<u8>, ()>>,
+}
+
+impl ReplayProtector {
+    /// Create a new ReplayProtector
+    #[allow(unused_variables)]
+    pub fn new(config_type: ServerType) -> ReplayProtector {
+        ReplayProtector {
+            #[cfg(feature = "security-replay-attack-detect")]
+            nonce_ppbloom: SpinMutex::new(PingPongBloom::new(config_type)),
+            #[cfg(feature = "aead-cipher-2022")]
+            nonce_set: SpinMutex::new(LruCache::with_expiry_duration(Duration::from_secs(
+                SERVER_STREAM_TIMESTAMP_MAX_DIFF,
+            ))),
+        }
+    }
+
+    /// Check if nonce exist or not
+    #[inline(always)]
+    pub fn check_nonce_and_set(&self, method: CipherKind, nonce: &[u8]) -> bool {
+        // Plain cipher doesn't have a nonce
+        // Always treated as non-duplicated
+        if nonce.is_empty() {
+            return false;
+        }
+
+        #[cfg(feature = "aead-cipher-2022")]
+        if method.is_aead_2022() {
+            let mut set = self.nonce_set.lock();
+            if set.get(nonce).is_some() {
+                return true;
+            }
+            set.insert(nonce.to_vec(), ());
+            return false;
+        }
 
-cfg_if! {
-    if #[cfg(feature = "security-replay-attack-detect")] {
-        mod ppbloom;
-        pub use self::ppbloom::*;
-    } else {
-        mod dummy;
-        pub use self::dummy::*;
+        cfg_if! {
+            if #[cfg(feature = "security-replay-attack-detect")] {
+                let mut ppbloom = self.nonce_ppbloom.lock();
+                ppbloom.check_and_set(nonce)
+            } else {
+                false
+            }
+        }
     }
 }