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.
Set flags by default:
-Wmissing-prototypes
-Wmissing-declarations
-Wstrict-prototypes
-Wwrite-strings
-Wcast-align
-Wbad-function-cast
-Wformat-security
-Wno-format-nonliteral
-Wmissing-format-attribute
-funsigned-char
Fix minor compiler warnings for these new flags on gcc and clang.
Instead of the linked list of engines setup an array
with the engines. This should provide better locality.
Also shrink the engine structure so that we can fit
2 on a cacheline.
Remove the FreeFunc from the runtime engines. Engines
now have a 'gid' (global id) that can be used to look
up the registered Free function.
Register keywords globally at start up.
Create a map of the registery per detection engine. This we need because
the sgh_mpm_context value is set per detect engine.
Remove APP_MPMS_MAX.
Introduce prefilter keyword to force a keyword to be used as prefilter.
e.g.
alert tcp any any -> any any (content:"A"; flags:R; prefilter; sid:1;)
alert tcp any any -> any any (content:"A"; flags:R; sid:2;)
alert tcp any any -> any any (content:"A"; dsize:1; prefilter; sid:3;)
alert tcp any any -> any any (content:"A"; dsize:1; sid:4;)
In sid 2 and 4 the content keyword is used in the MPM engine.
In sid 1 and 3 the flags and dsize keywords will be used.
Instead of the binary yes/no whitelisting used so far, use different
values for different sorts of whitelist reasons. The port list will
be sorted by whitelist value first, then by rule count.
The goal is to whitelist groups that have weak sigs:
- 1 byte pattern groups
- SYN sigs
Rules that check for SYN packets are mostly scan detection rules.
They will be checked often as SYN packets are very common.
e.g. alert tcp any any -> any 22 (flags:S,12; sid:123;)
This patch adds whitelisting for SYN-sigs, so that the sigs end up
in as unique groups as possible.
- negated mpm sigs
Currently negated mpm sigs are inspected often, so they are quite
expensive. For this reason, try to whitelist them.
These values are set during 'stage 1', rule preprocessing.
Since SYN inspecting rules are expensive, this patch splits the
'non-mpm' list (i.e. the rules that are always considered) into
a 'syn' and 'non-syn' list. The SYN list is only inspected if the
packet has the SYN flag set, otherwise the non-syn list is used.
The syn-list contains _all_ rules. The non-syn list contains all
minus the rules requiring the SYN bit in a packet.
The mpm_uricontent_maxlen logic was meant to track the shortest
possible pattern in the MPM of a SGH. So a minlen more than a maxlen.
This patch replaces the complicated tracking logic by a simpler
scheme. When the SGH's are finalize, the minlen is calculated.
It also fixes a small corner case where the calculated "maxlen" could
be wrong. This would require a smaller pattern in a rule to be forced
as fast pattern.
Treat negated MPM sigs as if non-MPM, so we consider them always.
As MPM results and non-MPM rules lists are now merged and considered
for further inspection, rules that need to be considerd when a pattern
is absent are caught in the middle.
As a HACK/workaround this patch adds them to the non-MPM list. This
causes them to be inspected each time.
Array of rule id's that are not using MPM prefiltering. These will be
merged with the MPM results array. Together these should lead to a
list of all the rules that can possibly match.
Makes use of 8-wide byte compare instructions in signature matching.
For allocating aligned memory, _mm_malloc() is SSE only, so added
check for __tile__ to use memalign() instead.
Shows a 13% speed up.
Victor Julien
Andreas Herz
Duarte Silva
Jason Ish
Ken Steele
Eric Leblond