Make sure all file sig mismatches indicate this in their return
code, not just the ones with filestore enabled. This is needed
to tell the stateful detect engine that it is dealing with a file
sig, so it can make sure these are inspected correctly even if
there are possibly multiple files per tx.
Fix the inspection of multiple files in a single TX, where new files
may be added to the TX after inspection started.
Assign the hard coded id DE_STATE_FLAG_FILE_INSPECT to the file
inspect engine.
Make sure that sigs that do file inspection and don't match on the
current file always store a detailed state. This state will include
the DE_STATE_FLAG_FILE_INSPECT flag.
When the app-layer indicates a new file is available, for each sig
that has the DE_STATE_FLAG_FILE_INSPECT flag set, reset part of the
state so that the sig is evaluated again.
Use per tx detect_flags to track prefilter. Detect flags are used for 2
things:
1. marking tx as fully inspected
2. tracking already run prefilter (incl mpm) engines
This supercedes the MpmIDs API for directionless tracking
of the prefilter engines.
When we have no SGH we have to flag the txs that are 'complete'
as inspected as well.
Special handling for the stream engine:
If a rule mixes TX inspection and STREAM inspection, we can encounter
the case where the rule is evaluated against multiple transactions
during a single inspection run. As the stream data is exactly the same
for each of those runs, it's wasteful to rerun inspection of the stream
portion of the rule.
This patch enables caching of the stream 'inspect engine' result in
the local 'RuleMatchCandidateTx' array. This is valid only during the
live of a single inspection run.
Remove stateful inspection from 'mask' (SignatureMask). The mask wasn't
used in most cases for those rules anyway, as there we rely on the
prefilter. Add a alproto check to catch the remaining cases.
When building the active non-mpm/non-prefilter list check not just
the mask, but also the alproto. This especially helps stateful rules
with negated mpm.
Simplify AppLayerParserHasDecoderEvents usage in detection to only
return true if protocol detection events are set. Other detection is done
in inspect engines.
Move rule group lookup and handling into it's own function. Handle
'post lookup' tasks immediately, instead of after the first detect
run. The tasks were independent of the initial detection.
Many cleanups and much refactoring.
Inspect engines are called per signature per sigmatch list. Most
wrap around DetectEngineContentInspection, but it's more generic.
Until now, the inspect engines were setup in a large per ipproto,
per alproto, per direction table. For stateful inspection each
engine needed a global flag.
This approach had a number of issues:
1. inefficient: each inspection round walked the table and then
checked if the inspect engine was even needed for the current
rule.
2. clumsy registration with global flag registration.
3. global flag space was approaching the need for 64 bits
4. duplicate registration for alprotos supporting both TCP and
TCP (DNS).
This patch introduces a new approach.
First, it does away with the per ipproto engines. This wasn't used.
Second, it adds a per signature list of inspect engine containing
only those engines that actually apply to the rule.
Third, it gets rid of the global flags and replaces it with flags
assigned per rule per engine.
Match on server name indication (SNI) extension in TLS using tls_sni
keyword, e.g:
alert tls any any -> any any (msg:"SNI test"; tls_sni;
content:"example.com"; sid:12345;)
When multiple files were in a tx, the first one(s) closed/complete
and a new open one as well, a match in the former could lead to not
inspecting the latter.
This patch adds a workaround for this case, by allowing the file
inspection code to return a special code for 'match, but more files
available in tx'.
The stateful detection engine will then not make this match final for
the tx. It relies on the file pruning to kick in to make sure the
already complete files are removed from the tx before the next time
the detection engine is called on the tx.
The app layer state 'version' field is incremented with each update
to the state. It is used by the detection engine to see if the current
version of the state has already been inspected. Since app layer and
detect always run closely together there is no need for a big number
here. The detect code really only checks for equal/not-equal, so wrap
arounds are not an issue.
If for a packet we have a TX N that has detect state and a TX N+1 that
has no detect state, but does have 'progress', we have a corner case
in stateful detection.
ContinueDetection inspects TX N, but cannot flag the rule in the
de_state_sig_array as the next (TX N+1) has already started and needs
to be inspected. 'StartDetection' however, is then unaware of the fact
that ContinueDetection already inspected the rule. It uses the per
session 'inspect_id' that is only moved forward at the end of the
detection run.
This patch adds a workaround. It uses the DetectEngineThreadCtx::
de_state_sig_array to store an offset between the 'base' inspect_id
and the inspect_id that StartDetection should use. The data type is
limited, so if the offset would be too big, a search based fall back
is implemented as well.
Use separate data structures for storing TX and FLOW (AMATCH) detect
state.
- move state storing into util funcs
- remove de_state_m
- simplify reset state logic on reload
Make DeStateDetectContinueDetection get it's own alstate pointer instead
of using the one that was passed to it. We now get and use it only
inside a flow lock.
Make DeStateDetectStartDetection get it's own alstate pointer instead
of using the one that was passed to it. We now get and use it only
inside a flow lock.
When generating an alert and storing it in the packet, store the tx_id
as well. This way the output modules can log the tx_id and access the
proper tx for logging.
Issue #904.
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.
To reload ruleset during engine runtime, send the USR2 signal to the engine, and the ruleset would be reloaded from the same yaml file supplied at engine startup
Victor Julien
Mats Klepsland
Jason Ish
Giuseppe Longo
DIALLO David
Anoop Saldanha
Anoop Saldanha