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fix crash on undersized buffers going through the lenses

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Co-authored-by: wucke13 <wucke13@gmail.com>
This commit is contained in:
Karolin Varner
2023-11-12 13:42:53 +01:00
committed by Karolin Varner
parent 1223048b48
commit 93439858d1
3 changed files with 122 additions and 29 deletions
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2
rosenpass/src/lib.rs
View File

@@ -19,7 +19,7 @@ pub enum RosenpassError {
Oqs,
#[error("error from external library while calling OQS")]
OqsExternalLib,
#[error("buffer size mismatch, required {required_size} but only found {actual_size}")]
#[error("buffer size mismatch, required {required_size} but found {actual_size}")]
BufferSizeMismatch {
required_size: usize,
actual_size: usize,

40
rosenpass/src/msgs.rs
View File

@@ -143,7 +143,7 @@ macro_rules! data_lense(
pub fn check_size(len: usize) -> Result<(), RosenpassError>{
let required_size = $( $len + )+ 0;
let actual_size = len;
if required_size < actual_size {
if required_size != actual_size {
Err(RosenpassError::BufferSizeMismatch {
required_size,
actual_size,
@@ -199,23 +199,53 @@ macro_rules! data_lense(
type __ContainerType;
/// Create a lense to the byte slice
fn [< $type:snake >] $(< $($generic),* >)? (self) -> Result< $type<Self::__ContainerType, $( $($generic),+ )? >, RosenpassError>;
fn [< $type:snake >] $(< $($generic : LenseView),* >)? (self) -> Result< $type<Self::__ContainerType, $( $($generic),+ )? >, RosenpassError>;
/// Create a lense to the byte slice, automatically truncating oversized buffers
fn [< $type:snake _ truncating >] $(< $($generic : LenseView),* >)? (self) -> Result< $type<Self::__ContainerType, $( $($generic),+ )? >, RosenpassError>;
}
impl<'a> [< $type Ext >] for &'a [u8] {
type __ContainerType = &'a [u8];
fn [< $type:snake >] $(< $($generic),* >)? (self) -> Result< $type<Self::__ContainerType, $( $($generic),+ )? >, RosenpassError> {
fn [< $type:snake >] $(< $($generic : LenseView),* >)? (self) -> Result< $type<Self::__ContainerType, $( $($generic),+ )? >, RosenpassError> {
$type::<Self::__ContainerType, $( $($generic),+ )? >::check_size(self.len())?;
Ok($type ( self, $( $( ::core::marker::PhantomData::<$generic> ),+ )? ))
}
fn [< $type:snake _ truncating >] $(< $($generic : LenseView),* >)? (self) -> Result< $type<Self::__ContainerType, $( $($generic),+ )? >, RosenpassError> {
let required_size = $( $len + )+ 0;
let actual_size = self.len();
if actual_size < required_size {
return Err(RosenpassError::BufferSizeMismatch {
required_size,
actual_size,
});
}
[< $type Ext >]::[< $type:snake >](&self[..required_size])
}
}
impl<'a> [< $type Ext >] for &'a mut [u8] {
type __ContainerType = &'a mut [u8];
fn [< $type:snake >] $(< $($generic),* >)? (self) -> Result< $type<Self::__ContainerType, $( $($generic),+ )? >, RosenpassError> {
fn [< $type:snake >] $(< $($generic : LenseView),* >)? (self) -> Result< $type<Self::__ContainerType, $( $($generic),+ )? >, RosenpassError> {
$type::<Self::__ContainerType, $( $($generic),+ )? >::check_size(self.len())?;
Ok($type ( self, $( $( ::core::marker::PhantomData::<$generic> ),+ )? ))
}
fn [< $type:snake _ truncating >] $(< $($generic : LenseView),* >)? (self) -> Result< $type<Self::__ContainerType, $( $($generic),+ )? >, RosenpassError> {
let required_size = $( $len + )+ 0;
let actual_size = self.len();
if actual_size < required_size {
return Err(RosenpassError::BufferSizeMismatch {
required_size,
actual_size,
});
}
[< $type Ext >]::[< $type:snake >](&mut self[..required_size])
}
}
});
);

109
rosenpass/src/protocol.rs
View File

@@ -736,7 +736,7 @@ impl CryptoServer {
// TODO remove unnecessary copying between global tx_buf and per-peer buf
// TODO move retransmission storage to io server
pub fn initiate_handshake(&mut self, peer: PeerPtr, tx_buf: &mut [u8]) -> Result<usize> {
let mut msg = tx_buf.envelope::<InitHello<()>>()?; // Envelope::<InitHello>::default(); // TODO
let mut msg = tx_buf.envelope_truncating::<InitHello<()>>()?; // Envelope::<InitHello>::default(); // TODO
self.handle_initiation(peer, msg.payload_mut().init_hello()?)?;
let len = self.seal_and_commit_msg(peer, MsgType::InitHello, msg)?;
peer.hs()
@@ -793,7 +793,7 @@ impl CryptoServer {
let msg_in = rx_buf.envelope::<InitHello<&[u8]>>()?;
ensure!(msg_in.check_seal(self)?, seal_broken);
let mut msg_out = tx_buf.envelope::<RespHello<&mut [u8]>>()?;
let mut msg_out = tx_buf.envelope_truncating::<RespHello<&mut [u8]>>()?;
let peer = self.handle_init_hello(
msg_in.payload().init_hello()?,
msg_out.payload_mut().resp_hello()?,
@@ -805,7 +805,7 @@ impl CryptoServer {
let msg_in = rx_buf.envelope::<RespHello<&[u8]>>()?;
ensure!(msg_in.check_seal(self)?, seal_broken);
let mut msg_out = tx_buf.envelope::<InitConf<&mut [u8]>>()?;
let mut msg_out = tx_buf.envelope_truncating::<InitConf<&mut [u8]>>()?;
let peer = self.handle_resp_hello(
msg_in.payload().resp_hello()?,
msg_out.payload_mut().init_conf()?,
@@ -820,7 +820,7 @@ impl CryptoServer {
let msg_in = rx_buf.envelope::<InitConf<&[u8]>>()?;
ensure!(msg_in.check_seal(self)?, seal_broken);
let mut msg_out = tx_buf.envelope::<EmptyData<&mut [u8]>>()?;
let mut msg_out = tx_buf.envelope_truncating::<EmptyData<&mut [u8]>>()?;
let peer = self.handle_init_conf(
msg_in.payload().init_conf()?,
msg_out.payload_mut().empty_data()?,
@@ -1733,31 +1733,94 @@ impl CryptoServer {
mod test {
use super::*;
fn init_crypto_server() -> CryptoServer {
// always init libsodium before anything
#[test]
/// Ensure that the protocol implementation can deal with truncated
/// messages and with overlong messages.
///
/// This test performs a complete handshake between two randomly generated
/// servers; instead of delivering the message correctly at first messages
/// of length zero through about 1.2 times the correct message size are delivered.
///
/// Producing an error is expected on each of these messages.
///
/// Finally the correct message is delivered and the same process
/// starts again in the other direction.
///
/// Through all this, the handshake should still successfully terminate;
/// i.e. an exchanged key must be produced in both servers.
fn handles_incorrect_size_messages() {
crate::sodium::sodium_init().unwrap();
// initialize secret and public key for the crypto server
let (mut sk, mut pk) = (SSk::zero(), SPk::zero());
// Guranteed to have 8MiB of stack size
stacker::grow(8 * 1024 * 1024, || {
StaticKEM::keygen(sk.secret_mut(), pk.secret_mut()).expect("unable to generate keys");
});
const OVERSIZED_MESSAGE: usize = ((MAX_MESSAGE_LEN as f32) * 1.2) as usize;
type MsgBufPlus = Public<OVERSIZED_MESSAGE>;
CryptoServer::new(sk, pk)
const PEER0: PeerPtr = PeerPtr(0);
let (mut me, mut they) = make_server_pair().unwrap();
let (mut msgbuf, mut resbuf) = (MsgBufPlus::zero(), MsgBufPlus::zero());
// Process the entire handshake
let mut msglen = Some(me.initiate_handshake(PEER0, &mut *resbuf).unwrap());
loop {
if let Some(l) = msglen {
std::mem::swap(&mut me, &mut they);
std::mem::swap(&mut msgbuf, &mut resbuf);
msglen = test_incorrect_sizes_for_msg(&mut me, &*msgbuf, l, &mut *resbuf);
} else {
break;
}
}
/// The determination of the message type relies on reading the first byte of the message. Only
/// after that the length of the message is checked against the specified message type. This
/// test ensures that nothing breaks in the case of an empty message.
#[test]
#[should_panic = "called `Result::unwrap()` on an `Err` value: received empty message, ignoring it"]
fn handle_empty_message() {
let mut crypt = init_crypto_server();
let empty_rx_buf = [0u8; 0];
let mut tx_buf = [0u8; 0];
assert_eq!(
me.osk(PEER0).unwrap().secret(),
they.osk(PEER0).unwrap().secret()
);
});
}
crypt.handle_msg(&empty_rx_buf, &mut tx_buf).unwrap();
/// Used in handles_incorrect_size_messages() to first deliver many truncated
/// and overlong messages, finally the correct message is delivered and the response
/// returned.
fn test_incorrect_sizes_for_msg(
srv: &mut CryptoServer,
msgbuf: &[u8],
msglen: usize,
resbuf: &mut [u8],
) -> Option<usize> {
resbuf.fill(0);
for l in 0..(((msglen as f32) * 1.2) as usize) {
if l == msglen {
continue;
}
let res = srv.handle_msg(&msgbuf[..l], resbuf);
assert!(matches!(res, Err(_))); // handle_msg should raise an error
assert!(!resbuf.iter().find(|x| **x != 0).is_some()); // resbuf should not have been changed
}
// Apply the proper handle_msg operation
srv.handle_msg(&msgbuf[..msglen], resbuf).unwrap().resp
}
fn keygen() -> Result<(SSk, SPk)> {
// TODO: Copied from the benchmark; deduplicate
let (mut sk, mut pk) = (SSk::zero(), SPk::zero());
StaticKEM::keygen(sk.secret_mut(), pk.secret_mut())?;
Ok((sk, pk))
}
fn make_server_pair() -> Result<(CryptoServer, CryptoServer)> {
// TODO: Copied from the benchmark; deduplicate
let psk = SymKey::random();
let ((ska, pka), (skb, pkb)) = (keygen()?, keygen()?);
let (mut a, mut b) = (
CryptoServer::new(ska, pka.clone()),
CryptoServer::new(skb, pkb.clone()),
);
a.add_peer(Some(psk.clone()), pkb)?;
b.add_peer(Some(psk), pka)?;
Ok((a, b))
}
}