peer: zero out sessions when they're dropped

NOTE: I'm not entirely sure this is sufficient, but it's a start.

4 files changed, 27 insertions, 5 deletions

diff --git a/Cargo.lock b/Cargo.lock
index dfc9b50..4cd9c0a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -158,6 +158,14 @@ dependencies = [
 ]
 
 [[package]]
+name = "clear_on_drop"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "colored"
 version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1301,6 +1309,7 @@ dependencies = [
  "bytes 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "chacha20-poly1305-aead 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "chrono 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "clear_on_drop 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "colored 1.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "criterion 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "daemonize 0.2.3 (git+https://github.com/mcginty/daemonize)",
@@ -1401,6 +1410,7 @@ dependencies = [
 "checksum chacha20-poly1305-aead 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "77d2058ba29594f69c75e8a9018e0485e3914ca5084e3613cd64529042f5423b"
 "checksum chrono 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7c20ebe0b2b08b0aeddba49c609fe7957ba2e33449882cb186a180bc60682fa9"
 "checksum clap 2.30.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1c07b9257a00f3fc93b7f3c417fc15607ec7a56823bc2c37ec744e266387de5b"
+"checksum clear_on_drop 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "97276801e127ffb46b66ce23f35cc96bd454fa311294bced4bbace7baa8b1d17"
 "checksum colored 1.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b0aa3473e85a3161b59845d6096b289bb577874cafeaf75ea1b1beaa6572c7fc"
 "checksum constant_time_eq 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8ff012e225ce166d4422e0e78419d901719760f62ae2b7969ca6b564d1b54a9e"
 "checksum criterion 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "9e8852a0db5351470bbae05adaf2f8247eb50bf61abad84dcddad025157a916c"
diff --git a/Cargo.toml b/Cargo.toml
index 2950455..6d3031e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -34,6 +34,7 @@ blake2-rfc = "0.2"
 byteorder = "^1.2"
 bytes = "0.4"
 chacha20-poly1305-aead = "^0.1"
+clear_on_drop = "^0.2"
 derive_deref = "^1.0"
 failure = "^0.1"
 futures = "^0.1"
diff --git a/src/lib.rs b/src/lib.rs
index a693518..d5dd0cf 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -19,6 +19,7 @@ extern crate blake2_rfc;
 extern crate byteorder;
 extern crate bytes;
 extern crate chacha20_poly1305_aead;
+extern crate clear_on_drop;
 extern crate hex;
 extern crate mio;
 extern crate nix;
diff --git a/src/peer.rs b/src/peer.rs
index 8bbc763..6fedf6f 100644
--- a/src/peer.rs
+++ b/src/peer.rs
@@ -1,5 +1,6 @@
 use anti_replay::AntiReplay;
 use byteorder::{ByteOrder, LittleEndian};
+use clear_on_drop::clear::{Clear, InitializableFromZeroed};
 use consts::{TRANSPORT_OVERHEAD, TRANSPORT_HEADER_SIZE, REKEY_AFTER_MESSAGES, REKEY_AFTER_TIME,
              REKEY_AFTER_TIME_RECV, REJECT_AFTER_TIME, REJECT_AFTER_MESSAGES, PADDING_MULTIPLE,
              MAX_QUEUED_PACKETS};
@@ -94,6 +95,15 @@ impl Session {
         })
     }
 }
+impl InitializableFromZeroed for Session {
+    unsafe fn initialize(_place: *mut Self) {}
+}
+
+fn wipe_session(mut session: Session) -> u32 {
+    let index = session.our_index;
+    session.clear();
+    index
+}
 
 pub struct IncompleteIncomingHandshake {
     their_index : u32,
@@ -122,7 +132,7 @@ impl Sessions {
                            mem::replace(&mut self.current, None),
                            mem::replace(&mut self.next,    None)];
 
-        indices.into_iter().filter_map(|sesh| sesh.map(|s| s.our_index)).collect()
+        indices.into_iter().filter_map(|sesh| sesh.map(wipe_session)).collect()
     }
 }
 
@@ -231,7 +241,7 @@ impl Peer {
 
         let old_next = mem::replace(&mut self.sessions.next, Some(session));
         let dead_index = if old_next.is_some() {
-            mem::replace(&mut self.sessions.past, old_next).map(|session| session.our_index)
+            mem::replace(&mut self.sessions.past, old_next).map(wipe_session)
         } else {
             None
         };
@@ -274,7 +284,7 @@ impl Peer {
         let     old_next        = mem::replace(&mut self.sessions.next, Some(next_session.into_transport_mode()?));
 
         let dead_index = if old_next.is_some() {
-            mem::replace(&mut self.sessions.past, old_next).map(|session| session.our_index)
+            mem::replace(&mut self.sessions.past, old_next).map(wipe_session)
         } else {
             None
         };
@@ -315,7 +325,7 @@ impl Peer {
         let current = mem::replace(&mut self.sessions.current, Some(session));
         let dead    = mem::replace(&mut self.sessions.past,    current);
 
-        Ok(dead.map(|session| session.our_index))
+        Ok(dead.map(wipe_session))
     }
 
     pub fn handle_incoming_transport(&mut self, addr: SocketAddr, packet: &Transport)
@@ -357,7 +367,7 @@ impl Peer {
             self.sessions.current.as_mut().unwrap().birthday = Timestamp::now();
             self.last_handshake                              = Timestamp::now();
 
-            Some(dead.map(|session| session.our_index))
+            Some(dead.map(wipe_session))
         } else {
             None
         };