Build SAML login (enterprise/internal/loginhandler), mirroring OIDC

Adds GET /auth/saml/login + POST /auth/saml/acs alongside the existing
OIDC pair, both converging on the same upsert-user/resolve-tenant/
issue-session path. loginhandler.New now takes an optional
*saml.ServiceProvider, RegisterRoutes registers each protocol's routes
independently so either, both, or neither can be configured. SAML's
replay/unsolicited-response defense (InResponseTo, standing in for
OIDC's state) is carried via a SameSite=None sentry_saml_request cookie
-- None because the ACS endpoint receives a cross-site POST from the
IdP's origin, which SameSite=Lax cookies are never sent on.
enterprise-auth's main.go now fetches+parses SAML_IDP_METADATA_URL at
startup (samlsp.FetchMetadata) and wires the result through.

Verified to the same bar as OIDC: a real fake IdP
(crewjam/saml/samlidp, genuine XML signing/verification) drives the
full login->ACS->session-cookie round trip and negative paths (bad
InResponseTo, missing request cookie, missing email/NameID, no/multiple
tenant memberships), all in loginhandler/saml_test.go, no Docker
needed. The login-form HTML is bypassed by pre-seeding a saml.Session
directly into samlidp's session store and presenting the matching
`session` cookie -- an IdP-supported shortcut (confirmed by reading
GetSession), the same "skip the UI, keep the crypto real" approach
oidctest gave the OIDC tests.

Writing that test caught two real bugs in internal/saml.ParseResponse,
both fixed here: it never called r.ParseForm() before reading the
POSTed SAMLResponse field, so every real ACS POST would have silently
decoded an empty response; and its email-attribute matching missed
urn:oid:0.9.2342.19200300.100.1.3 (the standard LDAP "mail" OID), which
is what an IdP sends by default absent an explicit
AttributeConsumingService request for "email" -- exactly what
samlidp's own DefaultAssertionMaker does, and plausibly what real IdPs'
default SAML app templates do too.

Docs (CLAUDE.md, threat-model.md, architecture.md, enterprise/README.md,
phase-4-runbook.md, docker-compose.yml's enterprise-auth comment)
updated in lockstep: SAML login moves from "protocol mechanics only" to
"built, verified with a real fake IdP, not yet tried against a real
external IdP or a running enterprise-auth container" -- the same
disclosed gap OIDC already carried.

This commit is contained in:

jcoffey-dev

2026-08-14 06:39:36 -07:00

parent 3037b31b0f

commit 08a90a27aa

14 changed files with 825 additions and 149 deletions

									
										enterprise/go.mod
									
		+1
		
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				@@ -37,6 +37,7 @@ require (

					github.com/cespare/xxhash/v2 v2.3.0 // indirect

					github.com/go-faster/city v1.0.1 // indirect

					github.com/go-faster/errors v0.7.1 // indirect

					github.com/golang-jwt/jwt/v4 v4.5.2 // indirect

					github.com/jackc/pgpassfile v1.0.0 // indirect

					github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect

					github.com/jackc/puddle/v2 v2.2.2 // indirect