Calling a function in unwrap_or causes that function to always
be called even when not needed. Instead use unwrap_or_else with
a closure which will only be called when needed.
Based on the Rust clippy lint that recommends that any public
function that dereferences a raw pointer, mark all FFI functions
that reference raw pointers with build_slice and cast_pointer
as unsafe.
This commits starts by removing the unsafe wrapper inside
the build_slice and cast_pointer macros then marks all
functions that use these macros as unsafe.
Then fix all not_unsafe_ptr_arg_deref warnings from clippy.
Fixes clippy lint:
https://rust-lang.github.io/rust-clippy/master/index.html#not_unsafe_ptr_arg_deref
All cases of our transmute can be replaced with more idiomatic
solutions and do no require the power of transmute.
When returning an object to C for life-time management, use
Box::into_raw to convert the boxed object to pointer and use
Box::from_raw to convert back.
For cases where we're just returning a pointer to Rust managed
data, use a cast.
Before, even if there were no outputs, all the arguments
were evaluated, which could turn expensive
All variables which are used only in certain build configurations
are now prefixed by underscore to avoid warnings
Lately, some of the TLS data was misdetected as DCERPC/TCP because of
the pattern |05 00|. Add more checks in DCERPC probe function to ensure
that it is in fact DCERPC/TCP.
Lately, Wireguard proto starting w pattern |04 00| is misdetected as
DCERPC/UDP which also starts with the same pattern, add more checks
to make sure that it is the best guess for packet to be dcerpc/udp.
The book defines transmute as "This is really, truly, the most horribly unsafe
thing you can do in Rust. The guardrails here are dental floss."
Transmute can result into mind boggling undefined behaviors. Get rid of
it wherever possible.
Since the completion status was a constant for all parsers, remove the
callback logic and instead register the values themselves. This should
avoid a lot of unnecessary callback calls.
Update all parsers to take advantage of this.
Implement missing transaction handling.
Fix logging wrongly casting 'state' to DCERPCState instead of
DCERPCUDPState leading to crashes and malformed output.
Remove unused fields from DCERPCUDPState.
Log fields that only are meant to be in a PDU for a particular RPC
version. Since DCERPC/UDP works on RPC version 4 and DCERPC/TCP works on
RPC version 5, there are certain fields that are particular to each
version.
Remove call_id from the logger for UDP.
Add activityuuid and seqnum fields to the logger for UDP.
call_id and (activityuuid + seqnum) fields are used to uniquely pair a
request with response for RPC versions 5 and 4 respectively.
So far, request and response were paired with serial number fields in
the header. This is incorrect. According to
https://pubs.opengroup.org/onlinepubs/9629399/chap12.htm,
"Together, the activity UUID and the sequence number uniquely identify
a remote procedure call."
Hence, add activity uuid and sequence number to the transaction and pair
the request accordingly. Remove incorrect handling of this and fix
tests.
warning: variable does not need to be mutable
--> src/dcerpc/dcerpc.rs:1036:42
|
1036 | let tx = if let Some(mut tx) = self.get_tx_by_call_id(current_call_id, core::STREAM_TOCLIENT) {
| ----^^
| |
| help: remove this `mut`
|
= note: `#[warn(unused_mut)]` on by default
warning: variable does not need to be mutable
--> src/dcerpc/dcerpc.rs:1061:30
|
1061 | Some(mut tx) => {
| ----^^
| |
| help: remove this `mut`
This patch addresses issues discovered by redmine ticket 3896. With the
approach of finding latest record, there was a chance that no record was
found at all and consumed + needed became input length.
e.g.
input_len = 1000
input = 01 05 00 02 00 03 a5 56 00 00 .....
There exists no |05 00| identifier in the rest of the record. After
having parsed |05 00|, there was a search for another record with the
leftover data. Current data length at this point would be 997. Since the
identifier was not found in the data, we calculate the consumed bytes at
this point i.e. consumed = current_data.len() - 1 which would be 996.
Needed bytes still stay at a constant of 2. So, consumed + needed = 996
+ 2 = 998 which is lesser than initial input length of 1000 and hence
the assertion fails.
There could be two fixes to this problem.
1. Finding the latest record but making use of the last found record in
case no new record was found.
2. Always use the earliest record.
This patch takes the approach (2). It also makes sure that the gap and
current direction are the same.
When one side of the connection reaches the STREAM_DEPTH condition the
parser should be aware of this. Otherwise transactions will forever be
waiting for data in that direction.
This parameter is NULL or the pointer to the previous state
for the previous protocol in the case of a protocol change,
for instance from HTTP1 to HTTP2
This way, the new protocol can use the old protocol context.
For instance, HTTP2 mimicks the HTTP1 request, to have a HTTP2
transaction with both request and response
DCERPC parser so far provided support for single transactions only.
Extend that to support multiple transactions.
In order for multiple transactions to work, there is always a
transaction identifier for any protocol in its header that lets a
response match the request. In DCERPC, for TCP, that param is call_id in
the header which is a 32 bit field. For UDP, however since it uses
different version of RPC (4.x), this is defined by serial number field
defined in the header. This field however is not contiguous and needs to
be assembled by the provided serial_low and serial_hi fields.
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.
Shivani Bhardwaj
Jason Ish
Philippe Antoine
Jeff Lucovsky
Victor Julien
Ilya Bakhtin