Feat/flowbit prefilter/v27 #12681
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Feat/flowbit prefilter/v27 #12681
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Allow for more efficient rules that 'prefilter' on flowbits with 'isset' logic. This prefilter is enabled by default, which means that if no mpm is present or no explicit prefilter is used, the flowbits prefilter will be set up for a rule. flowbits 'isset' prefilter For rules that have a 'flowbits:isset,<bit>' statement, a "regular" prefilter facility is created. It means that the rules are removed from the normal match list(s) and added to a prefilter engine that runs prior to the individual rule inspection stage. Implementation: the prefilter is implemented as an RB_TREE of flowbits, with the rule id's they "enable" stored per tree node. The matching logic is walking the list of bits set in the flow and looking each of them up in the RB_TREE, adding the rule ids of each of the matching bits to the list of rule candidates. The 'isset' prefilter has one important corner case, which is that bits can in fact be set during the rule evaluation stage. This is different from all other prefilter engines, that evaluate an immutable state (for the lifetime of the packets inspection). flowbits 'set' post-match prefilter For flowbits 'set' action, special post-match 'prefilter' facilities deal with this corner case. The high level logic is that these track which 'isset' sigs depend on them, and add these dependencies to the candidates list when a 'set' action occurs. This is implemented in a few steps: 1. flowbits 'set' is flagged 2. when 'set' action occurs the flowbit is added to a "post rule match work queue" 3. when the rule evaluation ends, the post-match "prefilter" engine is run on each of the flowbits in the "post rule match work queue" 4. these engines ammend the candidates list with the rule id dependencies for the flowbit 5. the candidates list is sorted to make sure within the execution for that packet the inspection order is maintained Ticket: OISF#2486.
Codecov ReportAttention: Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## master #12681 +/- ##
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Coverage 80.75% 80.75%
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Files 934 934
Lines 259594 260065 +471
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+ Hits 209634 210026 +392
- Misses 49960 50039 +79
Flags with carried forward coverage won't be shown. Click here to find out more. |
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I feel a bit like this post-prefilter logic could be useful more generally in the detect engine, in the sense that we run not only one prefilter stage. Like
And then, instead of evaluating each rule individually, we use the remaining prefilter engines. Like if my candidates have rules with |
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Assertion failed: (!(DeStateSearchState(state, direction, s->num))), function DeStateSignatureAppend, file detect-engine-state.c, line 127. with http-all-headers SV test and added rules |
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Information: QA ran without warnings. Pipeline 24911 |
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https://redmine.openinfosecfoundation.org/issues/2486
Rebase of #12662, also addresses review issues.
SV_BRANCH=OISF/suricata-verify#2317