app-layer.[ch], app-layer-detect-proto.[ch] and app-layer-parser.[ch].
Things addressed in this commit:
- Brings out a proper separation between protocol detection phase and the
parser phase.
- The dns app layer now is registered such that we don't use "dnstcp" and
"dnsudp" in the rules. A user who previously wrote a rule like this -
"alert dnstcp....." or
"alert dnsudp....."
would now have to use,
alert dns (ipproto:tcp;) or
alert udp (app-layer-protocol:dns;) or
alert ip (ipproto:udp; app-layer-protocol:dns;)
The same rules extend to other another such protocol, dcerpc.
- The app layer parser api now takes in the ipproto while registering
callbacks.
- The app inspection/detection engine also takes an ipproto.
- All app layer parser functions now take direction as STREAM_TOSERVER or
STREAM_TOCLIENT, as opposed to 0 or 1, which was taken by some of the
functions.
- FlowInitialize() and FlowRecycle() now resets proto to 0. This is
needed by unittests, which would try to clean the flow, and that would
call the api, AppLayerParserCleanupParserState(), which would try to
clean the app state, but the app layer now needs an ipproto to figure
out which api to internally call to clean the state, and if the ipproto
is 0, it would return without trying to clean the state.
- A lot of unittests are now updated where if they are using a flow and
they need to use the app layer, we would set a flow ipproto.
- The "app-layer" section in the yaml conf has also been updated as well.
Improved accuracy, improved performance. Performance improvement
noticeable with http heavy traffic and ruleset.
A lot of other cosmetic changes carried out as well. Wrappers introduced
for a lot of app layer functions.
Failing dce unittests disabled. Will be reintroduced in the updated dce
engine.
Cross transaction matching taken care of. FPs emanating from these
matches have now disappeared. Double inspection of transactions taken
care of as well.
When handling error case on SCMallog, SCCalloc or SCStrdup
we are in an unlikely case. This patch adds the unlikely()
expression to indicate this to gcc.
This patch has been obtained via coccinelle. The transformation
is the following:
@istested@
identifier x;
statement S1;
identifier func =~ "(SCMalloc|SCStrdup|SCCalloc)";
@@
x = func(...)
... when != x
- if (x == NULL) S1
+ if (unlikely(x == NULL)) S1
The filestore keyword until now flagged a file, tx or ssn for storage as soon
as the keyword was inspected. This happens before flowbits and some other
keywords, so files were stored that weren't supposed to.
This patch makes the filestore keyword fill an array in the detect engine
thread ctx. Then if the full signature matches, a post-match filestore
function makes the store final.
Filestore keyword by default (... filestore; ... ) marks only the file in the
same direction as the rule match for storing. This makes sense when inspecting
individual files (filemagic, filename, etc) but not so much when looking at
suspicious file requests, where the actual file is in the response.
The filestore keyword now takes 2 optional options:
filestore:<direction>,<scope>;
By default the direction is "same as rule match", and scope is "currently
inspected file".
For direction the following values are possible: "request" and "to_server",
"response" and "to_client", "both".
For scope the following values are possible: "tx" for all files in the current
HTTP/1.1 transation, "ssn" and "flow" for all files in the session/flow.
For the above case, where a suspious request should lead to a response file
download, this would work:
alert http ... content:"/suspicious/"; http_uri; filestore:response; ...
In stateful detection only inspect the file portion of the rule after all
other conditions matched. This to prevent "filestore" from tagging files
for storage during a partial match.
Add a couple of unittests to test the behaviour change.
Anoop Saldanha
Eric Leblond
Victor Julien