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fix(logstash source): Fix typo causing a panic on short requests (#21286
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* fix(logstash source): Fix typo causing a panic on short requests

The sources mistakenly check the original request instead of the current offset
to ensure there are enough bytes left when extracting integers in two places.
This can cause a panic in the `bytes::Buf` code if requests are cut off in the
middle of those integers.

* Fix clippy lints
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@bruceg
bruceg authored Sep 13, 2024
1 parent 9f56d46 commit e71016c
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Showing 2 changed files with 179 additions and 133 deletions.
1 change: 1 addition & 0 deletions changelog.d/21286-fix-logstash-frame-decode.fix.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fixed the `logstash` source coder to remove a panic that could trigger in the event of certain protocol errors.
311 changes: 178 additions & 133 deletions src/sources/logstash.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -520,148 +520,174 @@ impl Decoder for LogstashDecoder {
}
// https://github.com/logstash-plugins/logstash-input-beats/blob/master/PROTOCOL.md#data-frame-type
LogstashDecoderReadState::ReadFrame(protocol, LogstashFrameType::Data) => {
let mut rest = src.as_ref();

if rest.remaining() < 8 {
let Some(frame) = decode_data_frame(protocol, src) else {
return Ok(None);
}
let sequence_number = rest.get_u32();
let pair_count = rest.get_u32();

let mut fields = BTreeMap::<KeyString, serde_json::Value>::new();
for _ in 0..pair_count {
if src.remaining() < 4 {
return Ok(None);
}
let key_length = rest.get_u32() as usize;

if rest.remaining() < key_length {
return Ok(None);
}
let (key, right) = rest.split_at(key_length);
rest = right;

if src.remaining() < 4 {
return Ok(None);
}
let value_length = rest.get_u32() as usize;
if rest.remaining() < value_length {
return Ok(None);
}
let (value, right) = rest.split_at(value_length);
rest = right;

fields.insert(
String::from_utf8_lossy(key).into(),
String::from_utf8_lossy(value).into(),
);
}

let remaining = rest.remaining();
let byte_size = src.remaining() - remaining;

src.advance(byte_size);
};

let frames = vec![(
LogstashEventFrame {
protocol,
sequence_number,
fields,
},
byte_size,
)]
.into();

LogstashDecoderReadState::PendingFrames(frames)
LogstashDecoderReadState::PendingFrames([frame].into())
}
// https://github.com/logstash-plugins/logstash-input-beats/blob/master/PROTOCOL.md#json-frame-type
LogstashDecoderReadState::ReadFrame(protocol, LogstashFrameType::Json) => {
let mut rest = src.as_ref();

if rest.remaining() < 8 {
let Some(frame) = decode_json_frame(protocol, src)? else {
return Ok(None);
}
let sequence_number = rest.get_u32();
let payload_size = rest.get_u32() as usize;
};

if rest.remaining() < payload_size {
LogstashDecoderReadState::PendingFrames([frame].into())
}
// https://github.com/logstash-plugins/logstash-input-beats/blob/master/PROTOCOL.md#compressed-frame-type
LogstashDecoderReadState::ReadFrame(_protocol, LogstashFrameType::Compressed) => {
let Some(frames) = decode_compressed_frame(src)? else {
return Ok(None);
}
};

let (slice, right) = rest.split_at(payload_size);
rest = right;
LogstashDecoderReadState::PendingFrames(frames)
}
};
}
}
}

let fields_result: Result<BTreeMap<KeyString, serde_json::Value>, _> =
serde_json::from_slice(slice).context(JsonFrameFailedDecodeSnafu {});
/// Decode the Lumberjack version 1 protocol, which use the Key:Value format.
fn decode_data_frame(
protocol: LogstashProtocolVersion,
src: &mut BytesMut,
) -> Option<(LogstashEventFrame, usize)> {
let mut rest = src.as_ref();

let remaining = rest.remaining();
let byte_size = src.remaining() - remaining;
if rest.remaining() < 8 {
return None;
}
let sequence_number = rest.get_u32();
let pair_count = rest.get_u32();
if pair_count == 0 {
return None; // Invalid number of fields
}

src.advance(byte_size);
let mut fields = BTreeMap::<KeyString, serde_json::Value>::new();
for _ in 0..pair_count {
let (key, value, right) = decode_pair(rest)?;
rest = right;

match fields_result {
Ok(fields) => {
let frames = vec![(
LogstashEventFrame {
protocol,
sequence_number,
fields,
},
byte_size,
)]
.into();
fields.insert(
String::from_utf8_lossy(key).into(),
String::from_utf8_lossy(value).into(),
);
}

LogstashDecoderReadState::PendingFrames(frames)
}
Err(err) => return Err(err),
}
}
// https://github.com/logstash-plugins/logstash-input-beats/blob/master/PROTOCOL.md#compressed-frame-type
LogstashDecoderReadState::ReadFrame(_protocol, LogstashFrameType::Compressed) => {
let mut rest = src.as_ref();
let byte_size = bytes_remaining(src, rest);
src.advance(byte_size);

if rest.remaining() < 4 {
return Ok(None);
}
let payload_size = rest.get_u32() as usize;
Some((
LogstashEventFrame {
protocol,
sequence_number,
fields,
},
byte_size,
))
}

if rest.remaining() < payload_size {
src.reserve(payload_size);
return Ok(None);
}
fn decode_pair(mut rest: &[u8]) -> Option<(&[u8], &[u8], &[u8])> {
if rest.remaining() < 4 {
return None;
}
let key_length = rest.get_u32() as usize;

let (slice, right) = rest.split_at(payload_size);
rest = right;
if rest.remaining() < key_length {
return None;
}
let (key, right) = rest.split_at(key_length);
rest = right;

let mut buf = {
let mut buf = Vec::new();
if rest.remaining() < 4 {
return None;
}
let value_length = rest.get_u32() as usize;
if rest.remaining() < value_length {
return None;
}
let (value, right) = rest.split_at(value_length);
Some((key, value, right))
}

let res = ZlibDecoder::new(io::Cursor::new(slice))
.read_to_end(&mut buf)
.context(DecompressionFailedSnafu)
.map(|_| BytesMut::from(&buf[..]));
fn decode_json_frame(
protocol: LogstashProtocolVersion,
src: &mut BytesMut,
) -> Result<Option<(LogstashEventFrame, usize)>, DecodeError> {
let mut rest = src.as_ref();

let remaining = rest.remaining();
let byte_size = src.remaining() - remaining;
if rest.remaining() < 8 {
return Ok(None);
}
let sequence_number = rest.get_u32();
let payload_size = rest.get_u32() as usize;

src.advance(byte_size);
if rest.remaining() < payload_size {
return Ok(None);
}

res
}?;
let (slice, right) = rest.split_at(payload_size);
rest = right;

let mut decoder = LogstashDecoder::new();
let fields: BTreeMap<KeyString, serde_json::Value> =
serde_json::from_slice(slice).context(JsonFrameFailedDecodeSnafu {})?;

let mut frames = VecDeque::new();
let byte_size = bytes_remaining(src, rest);
src.advance(byte_size);

while let Some(s) = decoder.decode(&mut buf)? {
frames.push_back(s);
}
Ok(Some((
LogstashEventFrame {
protocol,
sequence_number,
fields,
},
byte_size,
)))
}

LogstashDecoderReadState::PendingFrames(frames)
}
};
}
fn decode_compressed_frame(
src: &mut BytesMut,
) -> Result<Option<VecDeque<(LogstashEventFrame, usize)>>, DecodeError> {
let mut rest = src.as_ref();

if rest.remaining() < 4 {
return Ok(None);
}
let payload_size = rest.get_u32() as usize;

if rest.remaining() < payload_size {
src.reserve(payload_size);
return Ok(None);
}

let (slice, right) = rest.split_at(payload_size);
rest = right;

let mut buf = Vec::new();

let res = ZlibDecoder::new(io::Cursor::new(slice))
.read_to_end(&mut buf)
.context(DecompressionFailedSnafu)
.map(|_| BytesMut::from(&buf[..]));

let byte_size = bytes_remaining(src, rest);
src.advance(byte_size);

let mut buf = res?;

let mut decoder = LogstashDecoder::new();

let mut frames = VecDeque::new();

while let Some(s) = decoder.decode(&mut buf)? {
frames.push_back(s);
}
Ok(Some(frames))
}

fn bytes_remaining(src: &BytesMut, rest: &[u8]) -> usize {
let remaining = rest.remaining();
src.remaining() - remaining
}

impl From<LogstashEventFrame> for Event {
Expand All @@ -685,6 +711,7 @@ impl From<LogstashEventFrame> for SmallVec<[Event; 1]> {
#[cfg(test)]
mod test {
use bytes::BufMut;
use futures::Stream;
use rand::{thread_rng, Rng};
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use vector_lib::lookup::OwnedTargetPath;
Expand Down Expand Up @@ -715,26 +742,32 @@ mod test {
test_protocol(EventStatus::Rejected, false).await;
}

async fn start_logstash(
status: EventStatus,
) -> (SocketAddr, impl Stream<Item = Event> + Unpin) {
let (sender, recv) = SourceSender::new_test_finalize(status);
let address = next_addr();
let source = LogstashConfig {
address: address.into(),
tls: None,
permit_origin: None,
keepalive: None,
receive_buffer_bytes: None,
acknowledgements: true.into(),
connection_limit: None,
log_namespace: None,
}
.build(SourceContext::new_test(sender, None))
.await
.unwrap();
tokio::spawn(source);
wait_for_tcp(address).await;
(address, recv)
}

async fn test_protocol(status: EventStatus, sends_ack: bool) {
let events = assert_source_compliance(&SOCKET_PUSH_SOURCE_TAGS, async {
let (sender, recv) = SourceSender::new_test_finalize(status);
let address = next_addr();
let source = LogstashConfig {
address: address.into(),
tls: None,
permit_origin: None,
keepalive: None,
receive_buffer_bytes: None,
acknowledgements: true.into(),
connection_limit: None,
log_namespace: None,
}
.build(SourceContext::new_test(sender, None))
.await
.unwrap();
tokio::spawn(source);
wait_for_tcp(address).await;

let (address, recv) = start_logstash(status).await;
spawn_collect_n(
send_req(address, &[("message", "Hello, world!")], sends_ack),
recv,
Expand Down Expand Up @@ -773,6 +806,18 @@ mod test {
req.into()
}

#[test]
fn v1_decoder_does_not_panic() {
let seq = thread_rng().gen_range(1..u32::MAX);
let req = encode_req(seq, &[("message", "Hello, World!")]);
for i in 0..req.len() - 1 {
assert!(
decode_data_frame(LogstashProtocolVersion::V1, &mut BytesMut::from(&req[..i]))
.is_none()
);
}
}

async fn send_req(address: SocketAddr, pairs: &[(&str, &str)], sends_ack: bool) {
let seq = thread_rng().gen_range(1..u32::MAX);
let mut socket = tokio::net::TcpStream::connect(address).await.unwrap();
Expand Down

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