This module uses the `der-parser` crate to parse ASN1 objects in order to replace src/util-decode-asn1.c
It also handles the parsing of the asn1 keyword rules and detection checks performed in src/detect-asn1.c
In case of lossy connections the SMB state would properly clean up
transactions, including file transactions. However for files the
state was never set to 'truncated', leading to files to stay 'active'.
This would lead these files staying in the SMB's state. In long running
sessions with lots of files this would lead to performance and memory
use issues.
This patch cleans truncates the file that was being transmitted when
a file transaction is being closed.
JsonBuilder is a Rust module for creating JSON output. Unlike
Jansson, the final JSON string is built up as items are added,
instead of building up an object tree and rendering it when
done.
The idea is to create a more efficient JSON serializer instead
of a flexible one.
To signal incomplete data, we must return the number of
consumed bytes. When we get a banner and some records, we have
to take into account the number of bytes already consumed by
the banner parsing before reaching an incomplete record.
All the dead code in C after the Rust implementation is hereby removed.
Invalid/migrated tests have also been deleted.
All the function calls in C have been replaced with appropriate calls to
Rust functions. Same has been done for smb/detect.rs as a part of this
migration.
This parser rewrites the DCE/RPC protocol implementation of Suricata
in Rust. More tests have been added to improve the coverage and some
fixes have been made to the tests already written in C. Most of the
valid tests from C have been imported to Rust.
File anatomy
src/dcerpc.rs
This file contains the implementation of single transactions in DCE/RPC
over TCP. It takes care of REQUEST, RESPONSE, BIND and BINDACK business
logic before and after the data parsing. DCERPCState holds the state
corresponding to a particular transaction and handles all important
aspects. It also defines any common structures and constants required
for DCE/RPC parsing irrespective of the carrier protocol.
src/dcerpc_udp.rs
This file contains the implementation of single transactions in DCE/RPC
over UDP. It takes care of REQUEST and RESPONSE parsing. It borrows the
Request and Response structs from src/dcerpc.rs.
src/detect.rs
This file contains the implementation of dce_iface and opnum detect
keywords. Both the parsing and the matching is taken care of by
functions in this file. Tests have been rewritten with the test data
from C.
src/parser.rs
This file contains all the nom parsers written for DCERPCRequest,
DCERPCResponse, DCERPCBind, DCERPCBindAck, DCERPCHeader, DCERPCHdrUdp.
It also implements functions to assemble and convert UUIDs. All the
fields have their endianness defined unless its an 8bit field or an
unusable one, then it's little endian but it won't make any difference.
src/mod.rs
This file contains all the modules of dcerpc folder which should be
taken into account during compilation.
Function calls
This is a State-wise implementation of the protocol for single
transaction only i.e. a valid state object is required to parse any
record. Function calls start with the app layer parser in C which
detects the application layer protocol to be DCE/RPC and calls the
appropriate functions in C which in turn make a call to these functions
in Rust using FFI. All the necessary information is passed from C to the
parsers and handlers in Rust.
Implementation
When a batch of input comes in, there is an analysis of whether the
input header and the direction is appropriate. Next check is about the
size of fragment. If it is as defined by the header, process goes
through else the data is buffered and more data is awaited. After this,
type of record as indicated by the header is checked. A call to the
appropriate handler is made. After the handling, State is updated with
the latest information about whatever record came in.
AppLayerResult::ok() is returned in case all went well else
AppLayerResult::err() is returned indicating something went wrong.
This commit adds an updated incomplete handling for the RFB-Parser. If
incomplete data is processed, the successfully consumed position and
length of remainder + 1 is returned. If the next packet is not empty
suricata will call the parser again.
This commit is a result of discussion on https://github.com/OISF/suricata/pull/4792.
Emmanuel Thompson
Jason Ish
Vadym Malakhatko
Jeff Lucovsky
Victor Julien
Shivani Bhardwaj
Philippe Antoine
frank honza