mt-broker-filter: Allow only requests from Triggers Subscriptions OIDC ID

[creydr]

Fixes #7989

Proposed Changes

• 🎁 Update mt-broker-filter to allow only requests from the triggers subscription OIDC id

Release Note

mt-broker-filter: Allow only requests from Triggers Subscriptions OIDC ID

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: creydr

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [creydr]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov]

Codecov Report

Attention: Patch coverage is 46.80851% with 25 lines in your changes missing coverage. Please review.

Project coverage is 67.75%. Comparing base (ecb6c01) to head (897d9ee).
Report is 5 commits behind head on main.

Files	Patch %	Lines
pkg/auth/token_verifier.go	0.00%	10 Missing ⚠️
pkg/broker/filter/filter_handler.go	60.00%	9 Missing and 1 partial ⚠️
pkg/reconciler/broker/resources/subscription.go	63.63%	1 Missing and 3 partials ⚠️
cmd/broker/filter/main.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8147      +/-   ##
==========================================
- Coverage   67.89%   67.75%   -0.14%     
==========================================
  Files         368      370       +2     
  Lines       17571    17915     +344     
==========================================
+ Hits        11930    12139     +209     
- Misses       4893     5001     +108     
- Partials      748      775      +27     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[creydr]

Can't really do a unit test, as tokenVerifier can only run inside a cluster, and for an e2e test it is too implementation specific :/. So tested via the following:

• created a broker, sink and trigger...
• run the tests to try to send events directly to the mt-broker-filter

with a token from the "default" service account:

k run curl --image=curlimages/curl --rm=true --restart=Never -ti -- -k -X POST -v -H "content-type: application/json"  -H "ce-specversion: 1.0" -H "ce-source: my/curl/command" -H "ce-type: my.demo.event" -H "ce-id: 0816" -H "Authorization: Bearer $(k create token default --audience "mt-broker-filter")" -d '{"name":"Hello"}' https://broker-filter.knative-eventing.svc.cluster.local/triggers/default/my-trigger/5d8c93e2-2837-41c8-a8f4-8710f11b427a
...
< HTTP/2 403

and in the mt-broker-filter logs:

{"level":"warn","ts":"2024-08-12T07:49:55.514Z","logger":"mt_broker_filter","caller":"filter/filter_handler.go:230","msg":"Error when validating the JWT token in the request","commit":"897d9ee-dirty","error":"token is from subject \"system:serviceaccount:default:default\", but only \"system:serviceaccount:default:my-broker-my-trigger-5d8c93e2-2ff563f9f3e3f325c50751600735ac587\" is allowed"}

then with a token from the SA which is of the triggers subscription:

k run curl --image=curlimages/curl --rm=true --restart=Never -ti -- -k -X POST -v -H "content-type: application/json"  -H "ce-specversion: 1.0" -H "ce-source: my/curl/command" -H "ce-type: my.demo.event" -H "ce-id: 0816" -H "Authorization: Bearer $(k create token my-broker-my-trigger-5d8c93e2-2ff563f9f3e3f325c50751600735ac587 --audience "mt-broker-filter")" -d '{"name":"Hello"}' https://broker-filter.knative-eventing.svc.cluster.local/triggers/default/my-trigger/5d8c93e2-2837-41c8-a8f4-8710f11b427a
...
< HTTP/2 400 #<- 400 is because of the sent events structure

and in the mt-broker-filter logs:

{"level":"debug","ts":"2024-08-12T07:54:53.365Z","logger":"mt_broker_filter","caller":"filter/filter_handler.go:234","msg":"Request contained a valid JWT. Continuing...","commit":"897d9ee-dirty"}

[creydr]

/cc @rahulii @Leo6Leo

[Leo6Leo]

/lgtm
I don't see any issues, and following the tests procedures above with my local build, get the same result. Thanks @creydr !

[creydr]

/test conformance-tests