Fix: Propagate every plugin header mutation in extproc and forwardproxy #760
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| package extproc | ||
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| import ( | ||
| "context" | ||
| "testing" | ||
|
|
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| extprocv3 "github.com/envoyproxy/go-control-plane/envoy/service/ext_proc/v3" | ||
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| "github.com/rossoctl/cortex/authbridge/authlib/pipeline" | ||
| "github.com/rossoctl/cortex/authbridge/authlib/plugins/plugintesting" | ||
| ) | ||
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| // hostCapture records the pctx.Host the listener built, so a test can assert | ||
| // what plugins actually see (Host is what SessionEvent.Host and the lineage | ||
|
Member
There was a problem hiding this comment. nit — This comment says Host is what "the lineage plugin's |
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| // plugin's lineage.peer.host fact are derived from). | ||
| type hostCapture struct { | ||
| host string | ||
| } | ||
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| func (p *hostCapture) Name() string { return "host-capture" } | ||
| func (p *hostCapture) Capabilities() pipeline.PluginCapabilities { | ||
| return pipeline.PluginCapabilities{} | ||
| } | ||
| func (p *hostCapture) OnResponse(context.Context, *pipeline.Context) pipeline.Action { | ||
| return pipeline.Action{Type: pipeline.Continue} | ||
| } | ||
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| func (p *hostCapture) OnRequest(_ context.Context, pctx *pipeline.Context) pipeline.Action { | ||
| p.host = pctx.Host | ||
| return pipeline.Action{Type: pipeline.Continue} | ||
| } | ||
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| func newHostCaptureServer(t *testing.T) (*Server, *hostCapture, *hostCapture) { | ||
| t.Helper() | ||
| in, out := &hostCapture{}, &hostCapture{} | ||
| inbound, err := plugintesting.BuildPipeline([]pipeline.Plugin{in}) | ||
| if err != nil { | ||
| t.Fatalf("building inbound pipeline: %v", err) | ||
| } | ||
| outbound, err := plugintesting.BuildPipeline([]pipeline.Plugin{out}) | ||
| if err != nil { | ||
| t.Fatalf("building outbound pipeline: %v", err) | ||
| } | ||
| return &Server{ | ||
| InboundPipeline: pipeline.NewHolder(inbound), | ||
| OutboundPipeline: pipeline.NewHolder(outbound), | ||
| }, in, out | ||
| } | ||
|
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| func runOne(t *testing.T, srv *Server, req *extprocv3.ProcessingRequest) { | ||
| t.Helper() | ||
| _ = srv.Process(&mockStream{ctx: context.Background(), requests: []*extprocv3.ProcessingRequest{req}}) | ||
| } | ||
|
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| // TestExtProc_Authority asserts both directions carry the request authority on | ||
| // pctx.Host, from either the HTTP/2 pseudo-header or the HTTP/1 Host header. | ||
| // Inbound used to be left empty, which cost every inbound observation the | ||
| // address the workload was reached on. | ||
| func TestExtProc_Authority(t *testing.T) { | ||
| cases := []struct { | ||
| name string | ||
| inbound bool | ||
| headers []string | ||
| wantHost string | ||
| }{ | ||
| { | ||
| name: "inbound from :authority", | ||
| inbound: true, | ||
| headers: []string{"x-authbridge-direction", "inbound", ":authority", "weather-service.team1.svc.cluster.local:8000", ":path", "/"}, | ||
| wantHost: "weather-service.team1.svc.cluster.local:8000", | ||
| }, | ||
| { | ||
| name: "inbound falls back to the host header", | ||
| inbound: true, | ||
| headers: []string{"x-authbridge-direction", "inbound", "host", "weather-service:8000", ":path", "/"}, | ||
| wantHost: "weather-service:8000", | ||
| }, | ||
| { | ||
| name: "outbound from :authority", | ||
| headers: []string{":authority", "weather-tool-mcp.team1.svc.cluster.local:8000", ":path", "/mcp"}, | ||
| wantHost: "weather-tool-mcp.team1.svc.cluster.local:8000", | ||
| }, | ||
| { | ||
| name: "outbound falls back to the host header", | ||
| headers: []string{"host", "weather-tool-mcp:8000", ":path", "/mcp"}, | ||
| wantHost: "weather-tool-mcp:8000", | ||
| }, | ||
| } | ||
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| for _, tc := range cases { | ||
| t.Run(tc.name, func(t *testing.T) { | ||
| srv, in, out := newHostCaptureServer(t) | ||
| headers := makeHeaders(tc.headers...) | ||
| if tc.inbound { | ||
| runOne(t, srv, inboundRequest(headers)) | ||
| if in.host != tc.wantHost { | ||
| t.Errorf("inbound pctx.Host = %q; want %q", in.host, tc.wantHost) | ||
| } | ||
| return | ||
| } | ||
| runOne(t, srv, outboundRequest(headers)) | ||
| if out.host != tc.wantHost { | ||
| t.Errorf("outbound pctx.Host = %q; want %q", out.host, tc.wantHost) | ||
| } | ||
| }) | ||
| } | ||
| } | ||
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must-fix — The header-propagation fix is sound, but this hunk (and its twin at line 190) is not the neutral telemetry fix the description claims. On the inbound path
:authority/Hostis caller-controlled, andpctx.Hostis read by decision-making plugins, not just recorded:plugins/ibac/plugin.go:352—matchesAnyHost(p.bypassHosts, pctx.Host)→pctx.Skip("host_bypass"), with no direction guard.defaultBypassHostsincludes keycloak/spire/otel, plus whateveragent_llm_hostis set to. Today in ext_proc inbound this branch is inert becausepctx.Hostis""; after this change a caller who setsHost: keycloak...skips IBAC judging entirely.plugins/opa/plugin.go:525—"host": pctx.Hostbecomes caller-controlled policy input.plugins/jwtvalidation/plugin.go:393— withaudience_mode: per-host, the expected audience is derived from the caller-supplied authority.This repo already documents the hazard and guards for it:
plugins/cpex/plugin.go:306-310gatesmatchesAnyHostbehindpctx.Direction == pipeline.Outbound, with the comment "the Host header is attacker-controlled and identity has NOT been pre-validated."Two ways forward, either is fine: (a) drop the two inbound
authorityOfhunks and keep the outbound consolidation (lines 469/511, a pure no-op refactor); or (b) land them together with a direction guard on ibac's host-bypass check. Worth notingreverseproxyalready populates inbound Host, so ibac's exposure pre-dates this PR — but this widens it to the ext_proc sidecar path, and that shouldn't ride along in a PR framed as header propagation.