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suricata/rust/src/ssh/ssh.rs

614 lines
22 KiB
Rust

/* Copyright (C) 2020 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
use super::parser;
use crate::applayer::*;
use crate::core::STREAM_TOSERVER;
use crate::core::{self, AppProto, Flow, ALPROTO_UNKNOWN, IPPROTO_TCP};
use std::ffi::{CStr, CString};
use std::mem::transmute;
use std::sync::atomic::{AtomicBool, Ordering};
static mut ALPROTO_SSH: AppProto = ALPROTO_UNKNOWN;
static HASSH_ENABLED: AtomicBool = AtomicBool::new(false);
fn hassh_is_enabled() -> bool {
HASSH_ENABLED.load(Ordering::Relaxed)
}
#[repr(u32)]
pub enum SSHEvent {
InvalidBanner = 0,
LongBanner,
InvalidRecord,
LongKexRecord,
}
impl SSHEvent {
fn from_i32(value: i32) -> Option<SSHEvent> {
match value {
0 => Some(SSHEvent::InvalidBanner),
1 => Some(SSHEvent::LongBanner),
2 => Some(SSHEvent::InvalidRecord),
3 => Some(SSHEvent::LongKexRecord),
_ => None,
}
}
}
#[repr(u8)]
#[derive(Copy, Clone, PartialOrd, PartialEq)]
pub enum SSHConnectionState {
SshStateInProgress = 0,
SshStateBannerWaitEol = 1,
SshStateBannerDone = 2,
SshStateFinished = 3,
}
const SSH_MAX_BANNER_LEN: usize = 256;
const SSH_RECORD_HEADER_LEN: usize = 6;
const SSH_MAX_REASSEMBLED_RECORD_LEN: usize = 65535;
pub struct SshHeader {
record_left: u32,
record_left_msg: parser::MessageCode,
flags: SSHConnectionState,
pub protover: Vec<u8>,
pub swver: Vec<u8>,
pub hassh: Vec<u8>,
pub hassh_string: Vec<u8>,
}
impl SshHeader {
pub fn new() -> SshHeader {
SshHeader {
record_left: 0,
record_left_msg: parser::MessageCode::SshMsgUndefined(0),
flags: SSHConnectionState::SshStateInProgress,
protover: Vec::new(),
swver: Vec::new(),
hassh: Vec::new(),
hassh_string: Vec::new(),
}
}
}
pub struct SSHTransaction {
pub srv_hdr: SshHeader,
pub cli_hdr: SshHeader,
de_state: Option<*mut core::DetectEngineState>,
events: *mut core::AppLayerDecoderEvents,
tx_data: AppLayerTxData,
}
impl SSHTransaction {
pub fn new() -> SSHTransaction {
SSHTransaction {
srv_hdr: SshHeader::new(),
cli_hdr: SshHeader::new(),
de_state: None,
events: std::ptr::null_mut(),
tx_data: AppLayerTxData::new(),
}
}
pub fn free(&mut self) {
if self.events != std::ptr::null_mut() {
core::sc_app_layer_decoder_events_free_events(&mut self.events);
}
if let Some(state) = self.de_state {
core::sc_detect_engine_state_free(state);
}
}
}
impl Drop for SSHTransaction {
fn drop(&mut self) {
self.free();
}
}
pub struct SSHState {
transaction: SSHTransaction,
}
impl SSHState {
pub fn new() -> Self {
Self {
transaction: SSHTransaction::new(),
}
}
fn set_event(&mut self, event: SSHEvent) {
let ev = event as u8;
core::sc_app_layer_decoder_events_set_event_raw(&mut self.transaction.events, ev);
}
fn parse_record(
&mut self, mut input: &[u8], resp: bool, pstate: *mut std::os::raw::c_void,
) -> AppLayerResult {
let (mut hdr, ohdr) = if !resp {
(&mut self.transaction.cli_hdr, &self.transaction.srv_hdr)
} else {
(&mut self.transaction.srv_hdr, &self.transaction.cli_hdr)
};
let il = input.len();
//first skip record left bytes
if hdr.record_left > 0 {
//should we check for overflow ?
let ilen = input.len() as u32;
if hdr.record_left > ilen {
hdr.record_left -= ilen;
return AppLayerResult::ok();
} else {
let start = hdr.record_left as usize;
match hdr.record_left_msg {
// parse reassembled tcp segments
parser::MessageCode::SshMsgKexinit if hassh_is_enabled() => {
if let Ok((_rem, key_exchange)) =
parser::ssh_parse_key_exchange(&input[..start])
{
key_exchange.generate_hassh(
&mut hdr.hassh_string,
&mut hdr.hassh,
&resp,
);
}
hdr.record_left_msg = parser::MessageCode::SshMsgUndefined(0);
}
_ => {}
}
input = &input[start..];
hdr.record_left = 0;
}
}
//parse records out of input
while input.len() > 0 {
match parser::ssh_parse_record(input) {
Ok((rem, head)) => {
SCLogDebug!("SSH valid record {}", head);
match head.msg_code {
parser::MessageCode::SshMsgKexinit if hassh_is_enabled() => {
//let endkex = SSH_RECORD_HEADER_LEN + head.pkt_len - 2;
let endkex = input.len() - rem.len();
if let Ok((_, key_exchange)) = parser::ssh_parse_key_exchange(&input[SSH_RECORD_HEADER_LEN..endkex]) {
key_exchange.generate_hassh(&mut hdr.hassh_string, &mut hdr.hassh, &resp);
}
}
parser::MessageCode::SshMsgNewKeys => {
hdr.flags = SSHConnectionState::SshStateFinished;
if ohdr.flags >= SSHConnectionState::SshStateFinished {
unsafe {
AppLayerParserStateSetFlag(
pstate,
APP_LAYER_PARSER_NO_INSPECTION
| APP_LAYER_PARSER_NO_REASSEMBLY
| APP_LAYER_PARSER_BYPASS_READY,
);
}
}
}
_ => {}
}
input = rem;
//header and complete data (not returned)
}
Err(nom::Err::Incomplete(_)) => {
match parser::ssh_parse_record_header(input) {
Ok((rem, head)) => {
SCLogDebug!("SSH valid record header {}", head);
let remlen = rem.len() as u32;
hdr.record_left = head.pkt_len - 2 - remlen;
//header with rem as incomplete data
match head.msg_code {
parser::MessageCode::SshMsgNewKeys => {
hdr.flags = SSHConnectionState::SshStateFinished;
}
parser::MessageCode::SshMsgKexinit if hassh_is_enabled() => {
// check if buffer is bigger than maximum reassembled packet size
hdr.record_left = head.pkt_len - 2;
if hdr.record_left < SSH_MAX_REASSEMBLED_RECORD_LEN as u32 {
// saving type of incomplete kex message
hdr.record_left_msg = parser::MessageCode::SshMsgKexinit;
return AppLayerResult::incomplete(
(il - rem.len()) as u32,
(head.pkt_len - 2) as u32
);
}
else {
SCLogDebug!("SSH buffer is bigger than maximum reassembled packet size");
self.set_event(SSHEvent::LongKexRecord);
}
}
_ => {}
}
return AppLayerResult::ok();
}
Err(nom::Err::Incomplete(_)) => {
//we may have consumed data from previous records
if input.len() < SSH_RECORD_HEADER_LEN {
//do not trust nom incomplete value
return AppLayerResult::incomplete(
(il - input.len()) as u32,
SSH_RECORD_HEADER_LEN as u32,
);
} else {
panic!("SSH invalid length record header");
}
}
Err(e) => {
SCLogDebug!("SSH invalid record header {}", e);
self.set_event(SSHEvent::InvalidRecord);
return AppLayerResult::err();
}
}
}
Err(e) => {
SCLogDebug!("SSH invalid record {}", e);
self.set_event(SSHEvent::InvalidRecord);
return AppLayerResult::err();
}
}
}
return AppLayerResult::ok();
}
fn parse_banner(
&mut self, input: &[u8], resp: bool, pstate: *mut std::os::raw::c_void,
) -> AppLayerResult {
let mut hdr = if !resp {
&mut self.transaction.cli_hdr
} else {
&mut self.transaction.srv_hdr
};
if hdr.flags == SSHConnectionState::SshStateBannerWaitEol {
match parser::ssh_parse_line(input) {
Ok((rem, _)) => {
let mut r = self.parse_record(rem, resp, pstate);
if r.is_incomplete() {
//adds bytes consumed by banner to incomplete result
r.consumed += (input.len() - rem.len()) as u32;
}
return r;
}
Err(nom::Err::Incomplete(_)) => {
return AppLayerResult::incomplete(0 as u32, (input.len() + 1) as u32);
}
Err(e) => {
SCLogDebug!("SSH invalid banner {}", e);
self.set_event(SSHEvent::InvalidBanner);
return AppLayerResult::err();
}
}
}
match parser::ssh_parse_line(input) {
Ok((rem, line)) => {
if let Ok((_, banner)) = parser::ssh_parse_banner(line) {
hdr.protover.extend(banner.protover);
if banner.swver.len() > 0 {
hdr.swver.extend(banner.swver);
}
hdr.flags = SSHConnectionState::SshStateBannerDone;
} else {
SCLogDebug!("SSH invalid banner");
self.set_event(SSHEvent::InvalidBanner);
return AppLayerResult::err();
}
if line.len() >= SSH_MAX_BANNER_LEN {
SCLogDebug!(
"SSH banner too long {} vs {}",
line.len(),
SSH_MAX_BANNER_LEN
);
self.set_event(SSHEvent::LongBanner);
}
let mut r = self.parse_record(rem, resp, pstate);
if r.is_incomplete() {
//adds bytes consumed by banner to incomplete result
r.consumed += (input.len() - rem.len()) as u32;
}
return r;
}
Err(nom::Err::Incomplete(_)) => {
if input.len() < SSH_MAX_BANNER_LEN {
//0 consumed, needs at least one more byte
return AppLayerResult::incomplete(0 as u32, (input.len() + 1) as u32);
} else {
SCLogDebug!(
"SSH banner too long {} vs {} and waiting for eol",
input.len(),
SSH_MAX_BANNER_LEN
);
if let Ok((_, banner)) = parser::ssh_parse_banner(input) {
hdr.protover.extend(banner.protover);
if banner.swver.len() > 0 {
hdr.swver.extend(banner.swver);
}
hdr.flags = SSHConnectionState::SshStateBannerWaitEol;
self.set_event(SSHEvent::LongBanner);
return AppLayerResult::ok();
} else {
self.set_event(SSHEvent::InvalidBanner);
return AppLayerResult::err();
}
}
}
Err(e) => {
SCLogDebug!("SSH invalid banner {}", e);
self.set_event(SSHEvent::InvalidBanner);
return AppLayerResult::err();
}
}
}
}
// C exports.
export_tx_get_detect_state!(rs_ssh_tx_get_detect_state, SSHTransaction);
export_tx_set_detect_state!(rs_ssh_tx_set_detect_state, SSHTransaction);
export_tx_data_get!(rs_ssh_get_tx_data, SSHTransaction);
#[no_mangle]
pub extern "C" fn rs_ssh_state_get_events(
tx: *mut std::os::raw::c_void,
) -> *mut core::AppLayerDecoderEvents {
let tx = cast_pointer!(tx, SSHTransaction);
return tx.events;
}
#[no_mangle]
pub extern "C" fn rs_ssh_state_get_event_info(
event_name: *const std::os::raw::c_char, event_id: *mut std::os::raw::c_int,
event_type: *mut core::AppLayerEventType,
) -> std::os::raw::c_int {
if event_name == std::ptr::null() {
return -1;
}
let c_event_name: &CStr = unsafe { CStr::from_ptr(event_name) };
let event = match c_event_name.to_str() {
Ok(s) => {
match s {
"invalid_banner" => SSHEvent::InvalidBanner as i32,
"long_banner" => SSHEvent::LongBanner as i32,
"invalid_record" => SSHEvent::InvalidRecord as i32,
"long_kex_record" => SSHEvent::LongKexRecord as i32,
_ => -1, // unknown event
}
}
Err(_) => -1, // UTF-8 conversion failed
};
unsafe {
*event_type = core::APP_LAYER_EVENT_TYPE_TRANSACTION;
*event_id = event as std::os::raw::c_int;
};
0
}
#[no_mangle]
pub extern "C" fn rs_ssh_state_get_event_info_by_id(
event_id: std::os::raw::c_int, event_name: *mut *const std::os::raw::c_char,
event_type: *mut core::AppLayerEventType,
) -> i8 {
if let Some(e) = SSHEvent::from_i32(event_id as i32) {
let estr = match e {
SSHEvent::InvalidBanner => "invalid_banner\0",
SSHEvent::LongBanner => "long_banner\0",
SSHEvent::InvalidRecord => "invalid_record\0",
SSHEvent::LongKexRecord => "long_kex_record\0",
};
unsafe {
*event_name = estr.as_ptr() as *const std::os::raw::c_char;
*event_type = core::APP_LAYER_EVENT_TYPE_TRANSACTION;
};
0
} else {
-1
}
}
#[no_mangle]
pub extern "C" fn rs_ssh_state_new(_orig_state: *mut std::os::raw::c_void, _orig_proto: AppProto) -> *mut std::os::raw::c_void {
let state = SSHState::new();
let boxed = Box::new(state);
return unsafe { transmute(boxed) };
}
#[no_mangle]
pub extern "C" fn rs_ssh_state_free(state: *mut std::os::raw::c_void) {
// Just unbox...
let _drop: Box<SSHState> = unsafe { transmute(state) };
}
#[no_mangle]
pub extern "C" fn rs_ssh_state_tx_free(_state: *mut std::os::raw::c_void, _tx_id: u64) {
//do nothing
}
#[no_mangle]
pub extern "C" fn rs_ssh_parse_request(
_flow: *const Flow, state: *mut std::os::raw::c_void, pstate: *mut std::os::raw::c_void,
input: *const u8, input_len: u32, _data: *const std::os::raw::c_void, _flags: u8,
) -> AppLayerResult {
let state = &mut cast_pointer!(state, SSHState);
let buf = build_slice!(input, input_len as usize);
let hdr = &mut state.transaction.cli_hdr;
if hdr.flags < SSHConnectionState::SshStateBannerDone {
return state.parse_banner(buf, false, pstate);
} else {
return state.parse_record(buf, false, pstate);
}
}
#[no_mangle]
pub extern "C" fn rs_ssh_parse_response(
_flow: *const Flow, state: *mut std::os::raw::c_void, pstate: *mut std::os::raw::c_void,
input: *const u8, input_len: u32, _data: *const std::os::raw::c_void, _flags: u8,
) -> AppLayerResult {
let state = &mut cast_pointer!(state, SSHState);
let buf = build_slice!(input, input_len as usize);
let hdr = &mut state.transaction.srv_hdr;
if hdr.flags < SSHConnectionState::SshStateBannerDone {
return state.parse_banner(buf, true, pstate);
} else {
return state.parse_record(buf, true, pstate);
}
}
#[no_mangle]
pub extern "C" fn rs_ssh_state_get_tx(
state: *mut std::os::raw::c_void, _tx_id: u64,
) -> *mut std::os::raw::c_void {
let state = cast_pointer!(state, SSHState);
return unsafe { transmute(&state.transaction) };
}
#[no_mangle]
pub extern "C" fn rs_ssh_state_get_tx_count(_state: *mut std::os::raw::c_void) -> u64 {
return 1;
}
#[no_mangle]
pub extern "C" fn rs_ssh_state_progress_completion_status(_direction: u8) -> std::os::raw::c_int {
return SSHConnectionState::SshStateFinished as i32;
}
#[no_mangle]
pub extern "C" fn rs_ssh_tx_get_flags(
tx: *mut std::os::raw::c_void, direction: u8,
) -> SSHConnectionState {
let tx = cast_pointer!(tx, SSHTransaction);
if direction == STREAM_TOSERVER {
return tx.cli_hdr.flags;
} else {
return tx.srv_hdr.flags;
}
}
#[no_mangle]
pub extern "C" fn rs_ssh_tx_get_alstate_progress(
tx: *mut std::os::raw::c_void, direction: u8,
) -> std::os::raw::c_int {
let tx = cast_pointer!(tx, SSHTransaction);
if tx.cli_hdr.flags >= SSHConnectionState::SshStateFinished
&& tx.srv_hdr.flags >= SSHConnectionState::SshStateFinished
{
return SSHConnectionState::SshStateFinished as i32;
}
if direction == STREAM_TOSERVER {
if tx.cli_hdr.flags >= SSHConnectionState::SshStateBannerDone {
return SSHConnectionState::SshStateBannerDone as i32;
}
} else {
if tx.srv_hdr.flags >= SSHConnectionState::SshStateBannerDone {
return SSHConnectionState::SshStateBannerDone as i32;
}
}
return SSHConnectionState::SshStateInProgress as i32;
}
// Parser name as a C style string.
const PARSER_NAME: &'static [u8] = b"ssh\0";
#[no_mangle]
pub unsafe extern "C" fn rs_ssh_register_parser() {
let default_port = CString::new("[22]").unwrap();
let parser = RustParser {
name: PARSER_NAME.as_ptr() as *const std::os::raw::c_char,
default_port: default_port.as_ptr(),
ipproto: IPPROTO_TCP,
//simple patterns, no probing
probe_ts: None,
probe_tc: None,
min_depth: 0,
max_depth: 0,
state_new: rs_ssh_state_new,
state_free: rs_ssh_state_free,
tx_free: rs_ssh_state_tx_free,
parse_ts: rs_ssh_parse_request,
parse_tc: rs_ssh_parse_response,
get_tx_count: rs_ssh_state_get_tx_count,
get_tx: rs_ssh_state_get_tx,
tx_get_comp_st: rs_ssh_state_progress_completion_status,
tx_get_progress: rs_ssh_tx_get_alstate_progress,
get_de_state: rs_ssh_tx_get_detect_state,
set_de_state: rs_ssh_tx_set_detect_state,
get_events: Some(rs_ssh_state_get_events),
get_eventinfo: Some(rs_ssh_state_get_event_info),
get_eventinfo_byid: Some(rs_ssh_state_get_event_info_by_id),
localstorage_new: None,
localstorage_free: None,
get_files: None,
get_tx_iterator: None,
get_tx_data: rs_ssh_get_tx_data,
apply_tx_config: None,
flags: 0,
truncate: None,
};
let ip_proto_str = CString::new("tcp").unwrap();
if AppLayerProtoDetectConfProtoDetectionEnabled(ip_proto_str.as_ptr(), parser.name) != 0 {
let alproto = AppLayerRegisterProtocolDetection(&parser, 1);
ALPROTO_SSH = alproto;
if AppLayerParserConfParserEnabled(ip_proto_str.as_ptr(), parser.name) != 0 {
let _ = AppLayerRegisterParser(&parser, alproto);
}
SCLogDebug!("Rust ssh parser registered.");
} else {
SCLogNotice!("Protocol detector and parser disabled for SSH.");
}
}
#[no_mangle]
pub extern "C" fn rs_ssh_enable_hassh() {
HASSH_ENABLED.store(true, Ordering::Relaxed)
}
#[no_mangle]
pub extern "C" fn rs_ssh_hassh_is_enabled() -> bool {
hassh_is_enabled()
}
#[no_mangle]
pub extern "C" fn rs_ssh_tx_get_log_condition( tx: *mut std::os::raw::c_void) -> bool {
let tx = cast_pointer!(tx, SSHTransaction);
if rs_ssh_hassh_is_enabled() {
if tx.cli_hdr.flags == SSHConnectionState::SshStateFinished &&
tx.srv_hdr.flags == SSHConnectionState::SshStateFinished {
return true;
}
}
else {
if tx.cli_hdr.flags == SSHConnectionState::SshStateBannerDone &&
tx.srv_hdr.flags == SSHConnectionState::SshStateBannerDone {
return true;
}
}
return false;
}