feat(engine): emit warning when a condition uses deprecated "evt.dir"

[irozzo-1A]

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind feature

/kind release

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area build

/area engine

/area tests

/area proposals

/area CI

What this PR does / why we need it:

Emit a warning when a rule with a condition using "evt.dir" field is encountered.
The direction have been deprecated in the scope of enter event suppression initiative.

ref: falcosecurity/libs#2588

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Example output:

Wed Oct 08 08:50:51 2025: rules/falco-deprecated_rules.yaml: Ok, with warnings
4 Warnings:
In rules content: (rules/falco-deprecated_rules.yaml:0:0)
    rule 'Disallowed SSH Connection': (rules/falco-deprecated_rules.yaml:82:2)
    rule condition: (rules/falco-deprecated_rules.yaml:88:13)
------
  condition: >
             ^
------
LOAD_DEPRECATED_ITEM (Used deprecated item: field 'evt.dir' is deprecated): due to the drop of enter events, 'evt.dir = <' always evaluates to true, and 'evt.dir = >' always evaluates to false. The rule expression can be simplified by removing the condition on 'evt.dir'
In rules content: (rules/falco-deprecated_rules.yaml:0:0)
    rule 'Unexpected outbound connection destination': (rules/falco-deprecated_rules.yaml:115:2)
    rule condition: (rules/falco-deprecated_rules.yaml:121:13)
------
  condition: >
             ^
------
LOAD_DEPRECATED_ITEM (Used deprecated item: field 'evt.dir' is deprecated): due to the drop of enter events, 'evt.dir = <' always evaluates to true, and 'evt.dir = >' always evaluates to false. The rule expression can be simplified by removing the condition on 'evt.dir'
In rules content: (rules/falco-deprecated_rules.yaml:0:0)
    rule 'Outbound or Inbound Traffic not to Authorized Server Process and Port': (rules/falco-deprecated_rules.yaml:155:2)
    rule condition: (rules/falco-deprecated_rules.yaml:163:13)
------
  condition: >
             ^
------
LOAD_DEPRECATED_ITEM (Used deprecated item: field 'evt.dir' is deprecated): due to the drop of enter events, 'evt.dir = <' always evaluates to true, and 'evt.dir = >' always evaluates to false. The rule expression can be simplified by removing the condition on 'evt.dir'
In rules content: (rules/falco-deprecated_rules.yaml:0:0)
    rule 'Outbound Connection to C2 Servers': (rules/falco-deprecated_rules.yaml:180:2)
    rule condition: (rules/falco-deprecated_rules.yaml:187:13)
------
  condition: >
             ^
------
LOAD_DEPRECATED_ITEM (Used deprecated item: field 'evt.dir' is deprecated): due to the drop of enter events, 'evt.dir = <' always evaluates to true, and 'evt.dir = >' always evaluates to false. The rule expression can be simplified by removing the condition on 'evt.dir'

Does this PR introduce a user-facing change?:

feat(engine): emit warning when a rule containing a condition on the deprecated `evt.dir` field is encountered

[github-actions]

This PR may bring feature or behavior changes in the Falco engine and may require the engine version to be bumped.

Please double check userspace/engine/falco_engine_version.h file. See versioning for FALCO_ENGINE_VERSION.

/hold

[leogr]

/milestone 0.42.0

[mstemm]

I'd suggest making the error a bit more generic, but I can live with it as written.

[poiana]

LGTM label has been added.

Git tree hash: 7ef95de6bea5d29dc3d232471325e195ad89b27d

[poiana]

LGTM label has been added.

Git tree hash: a408e32011e828ef6e5a8b29b9bcaed7ae1f0577

[leogr]

This PR may bring feature or behavior changes in the Falco engine and may require the engine version to be bumped.

Please double check userspace/engine/falco_engine_version.h file. See versioning for FALCO_ENGINE_VERSION.

/hold

false positive
/remove-hold

[leogr]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: irozzo-1A, leogr

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