feat(saml): wire SAML 2.0 SSO end-to-end (pure-Rust) + Settings/Storage UI consolidation (v0.5.1)

SAML SSO (the config was storage-only since v0.4.5; now it logs you in):
- New openpxe-core::saml — pure-Rust SP built on bergshamra (XML-DSig +
  exclusive c14n via RustCrypto, no OpenSSL/xmlsec/libxml2). The static
  musl binary stays C-free; samael was rejected for hard-requiring OpenSSL.
  * metadata.rs   — parse IdP EntityDescriptor (SSO URLs + signing certs),
                    build our SP metadata.
  * authn_request.rs — build + HTTP-Redirect-encode AuthnRequests.
  * response.rs   — verify the signature against the pinned IdP cert
                    (trusted_keys_only + strict_verification for XSW),
                    then enforce Status/Destination/Audience/time-bounds/
                    signature-scope. Stateless; returns the IDs the HTTP
                    layer needs.
- http-api saml_routes: GET /api/sso/login (302 to IdP), POST /api/sso/acs
  (verify -> InResponseTo correlation / IdP-initiated gating / assertion
  replay guard -> mint operator session -> 302), GET /api/sso/metadata.
  Added to the pre-auth allowlist; /api/sso config stays gated.
- SsoConfig gains entity_id (SP Entity ID, defaults to public base URL)
  and allow_idp_initiated (default off), mirroring FleetDM.
- Access model: any IdP-authenticated, cryptographically-verified user gets
  an operator session (single-tier; local admin remains the fallback owner).
- Login page: the "Sign in with <IdP>" button now drives the real flow and
  surfaces sso_error redirects.

UI consolidation:
- Removed the Advanced sidebar tab; folded its webhook-notifications +
  API-reference cards into a collapsible "Advanced" disclosure at the
  bottom of Settings.
- Merged the Storage tab's separate SMB and NFS cards into one "Remote
  shares" card with a protocol dropdown and a unified, protocol-badged
  table. No backend changes — same /api/smb-shares + /api/nfs-shares.

Tests: 17 SAML core tests (accept + reject tampered/unsigned/wrong-key/
wrong-audience/expired/future/wrong-issuer/non-success) and 6 ACS
integration tests (happy path, IdP-initiated gating, SP correlation,
replay, garbage). Full workspace: 206 tests green, clippy clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

crates/http-api/src/saml_routes.rs

@@ -0,0 +1,338 @@
+//! SAML 2.0 Service Provider HTTP endpoints (v0.5.1).
+//!
+//! * `GET  /api/sso/login`    — SP-initiated: build an AuthnRequest, record its
+//!   ID, and 302 the browser to the IdP.
+//! * `POST /api/sso/acs`      — Assertion Consumer Service: verify + validate
+//!   the IdP's `SAMLResponse`, perform the stateful checks (InResponseTo
+//!   correlation, IdP-initiated gating, assertion replay), mint an operator
+//!   session, and 302 to the dashboard. (Mirrors FleetDM's `/sso/callback`.)
+//! * `GET  /api/sso/metadata` — serve our SP metadata XML for IdP import.
+//!
+//! Stateless crypto + semantic validation live in `openpxe_core::saml`; this
+//! module owns only the HTTP glue and the in-memory state the SP needs.
+
+use std::collections::HashMap;
+use std::sync::Arc;
+use std::time::{Duration as StdDuration, Instant};
+
+use axum::{
+    body::Body,
+    extract::{Form, Query, State},
+    http::{header, StatusCode},
+    response::{IntoResponse, Response},
+};
+use base64::Engine;
+use parking_lot::Mutex;
+use serde::Deserialize;
+use time::{Duration, OffsetDateTime};
+
+use openpxe_core::saml::{self, metadata::IdpMetadata, SamlError, SpParams};
+use openpxe_core::SsoConfig;
+
+use crate::auth;
+use crate::state::AppState;
+
+/// Outstanding AuthnRequest IDs live at most this long before a matching
+/// response is considered stale (covers a slow human at the IdP login form).
+const REQUEST_TTL: StdDuration = StdDuration::from_mins(10);
+/// How long we fetch-cache IdP metadata loaded from a URL.
+const METADATA_FETCH_TIMEOUT: StdDuration = StdDuration::from_secs(10);
+
+/// In-memory SAML runtime state. Cheap to clone (Arc-shared).
+#[derive(Clone, Default)]
+pub struct SamlRuntime {
+    /// request_id → issued_at. Correlates a response's `InResponseTo` to a
+    /// request *we* actually sent (replay / CSRF defense for SP-initiated).
+    outstanding: Arc<Mutex<HashMap<String, Instant>>>,
+    /// assertion_id → expiry. A consumed assertion may not be replayed.
+    consumed: Arc<Mutex<HashMap<String, Instant>>>,
+    /// Cache of IdP metadata fetched from a URL: (url, parsed).
+    metadata_cache: Arc<Mutex<Option<(String, IdpMetadata)>>>,
+}
+
+impl SamlRuntime {
+    /// Record an AuthnRequest we just sent.
+    pub fn register_request(&self, id: &str) {
+        let mut g = self.outstanding.lock();
+        prune(&mut g);
+        g.insert(id.to_owned(), Instant::now());
+    }
+
+    /// Consume an outstanding request ID, returning `true` if it was present
+    /// and still fresh. A miss means the response doesn't correlate to any
+    /// live request we issued.
+    pub fn take_request(&self, id: &str) -> bool {
+        let mut g = self.outstanding.lock();
+        prune(&mut g);
+        g.remove(id).is_some()
+    }
+
+    /// Record a consumed assertion. Returns `false` if it was already
+    /// consumed (a replay) — in which case the caller must reject.
+    pub fn record_assertion(&self, id: &str, expiry: OffsetDateTime) -> bool {
+        let mut g = self.consumed.lock();
+        prune(&mut g);
+        if g.contains_key(id) {
+            return false;
+        }
+        let ttl = (expiry - OffsetDateTime::now_utc())
+            .max(Duration::ZERO)
+            .unsigned_abs();
+        g.insert(id.to_owned(), Instant::now() + ttl);
+        true
+    }
+
+    fn cached_metadata(&self, url: &str) -> Option<IdpMetadata> {
+        let g = self.metadata_cache.lock();
+        match &*g {
+            Some((cached_url, md)) if cached_url == url => Some(md.clone()),
+            _ => None,
+        }
+    }
+
+    fn cache_metadata(&self, url: String, md: IdpMetadata) {
+        *self.metadata_cache.lock() = Some((url, md));
+    }
+}
+
+/// Drop expired entries so neither map grows unbounded.
+fn prune(map: &mut HashMap<String, Instant>) {
+    let now = Instant::now();
+    // For the request map this over-prunes (entries store issued_at, not
+    // expiry), so cap by REQUEST_TTL; the consumed map stores absolute
+    // expiry instants. Using saturating logic keeps both correct: request
+    // entries older than REQUEST_TTL go, consumed entries past expiry go.
+    map.retain(|_, &mut t| now.saturating_duration_since(t) < REQUEST_TTL || t > now);
+}
+
+// ─── GET /api/sso/login ───────────────────────────────────────────────────
+
+#[derive(Debug, Deserialize)]
+pub struct LoginQuery {
+    /// Optional local path to return to after login (becomes RelayState).
+    #[serde(default)]
+    pub next: Option<String>,
+}
+
+pub async fn sso_login(State(state): State<AppState>, Query(q): Query<LoginQuery>) -> Response {
+    let cfg = state.sso.snapshot();
+    if !cfg.is_usable() {
+        return redirect("/?sso_error=unavailable");
+    }
+    let idp = match resolve_idp_metadata(&state, &cfg).await {
+        Ok(m) => m,
+        Err(e) => {
+            tracing::warn!(target: "openpxe::saml", "sso_login: metadata unavailable: {e}");
+            return redirect("/?sso_error=metadata");
+        }
+    };
+    let Some(dest) = idp.sso_destination().map(str::to_owned) else {
+        tracing::warn!(target: "openpxe::saml", "sso_login: IdP metadata has no SSO endpoint");
+        return redirect("/?sso_error=metadata");
+    };
+    let sp = sp_params(&state, &cfg);
+    let relay = safe_local_path(q.next.as_deref());
+    match saml::authn_request::build(&sp, &dest, Some(&relay)) {
+        Ok(req) => {
+            state.saml.register_request(&req.id);
+            redirect(&req.location)
+        }
+        Err(e) => {
+            tracing::warn!(target: "openpxe::saml", "sso_login: build AuthnRequest failed: {e}");
+            redirect("/?sso_error=request")
+        }
+    }
+}
+
+// ─── POST /api/sso/acs ──────────────────────────────────────────────────────
+
+#[derive(Debug, Deserialize)]
+pub struct AcsForm {
+    #[serde(rename = "SAMLResponse")]
+    pub saml_response: String,
+    #[serde(rename = "RelayState", default)]
+    pub relay_state: Option<String>,
+}
+
+pub async fn sso_acs(State(state): State<AppState>, Form(form): Form<AcsForm>) -> Response {
+    let cfg = state.sso.snapshot();
+    if !cfg.is_usable() {
+        return redirect("/?sso_error=unavailable");
+    }
+    let xml = match base64::engine::general_purpose::STANDARD.decode(form.saml_response.as_bytes())
+    {
+        Ok(bytes) => String::from_utf8_lossy(&bytes).into_owned(),
+        Err(e) => {
+            tracing::warn!(target: "openpxe::saml", "acs: base64 decode failed: {e}");
+            return redirect("/?sso_error=1");
+        }
+    };
+    let idp = match resolve_idp_metadata(&state, &cfg).await {
+        Ok(m) => m,
+        Err(e) => {
+            tracing::warn!(target: "openpxe::saml", "acs: metadata unavailable: {e}");
+            return redirect("/?sso_error=metadata");
+        }
+    };
+    let sp = sp_params(&state, &cfg);
+
+    // Signature verification + semantic checks are CPU-bound — keep them off
+    // the async executor.
+    let now = OffsetDateTime::now_utc();
+    let skew = Duration::seconds(saml::DEFAULT_CLOCK_SKEW_SECS);
+    let verify = {
+        let xml = xml.clone();
+        let sp = sp.clone();
+        tokio::task::spawn_blocking(move || saml::response::consume(&xml, &sp, &idp, now, skew))
+            .await
+    };
+    let verified = match verify {
+        Ok(Ok(v)) => v,
+        Ok(Err(e)) => {
+            // Never leak which specific check failed to the browser.
+            tracing::warn!(target: "openpxe::saml", "acs: response rejected: {e}");
+            return redirect("/?sso_error=1");
+        }
+        Err(join) => {
+            tracing::error!(target: "openpxe::saml", "acs: verify task panicked: {join}");
+            return redirect("/?sso_error=1");
+        }
+    };
+
+    // Stateful checks the core deliberately left to us.
+    match &verified.in_response_to {
+        Some(id) => {
+            if !state.saml.take_request(id) {
+                tracing::warn!(target: "openpxe::saml", "acs: InResponseTo matches no live request");
+                return redirect("/?sso_error=1");
+            }
+        }
+        None => {
+            if !cfg.allow_idp_initiated {
+                tracing::warn!(target: "openpxe::saml", "acs: IdP-initiated login is disabled");
+                return redirect("/?sso_error=idp_initiated");
+            }
+        }
+    }
+    if !state
+        .saml
+        .record_assertion(&verified.assertion_id, verified.assertion_expiry)
+    {
+        tracing::warn!(target: "openpxe::saml", "acs: assertion replay rejected");
+        return redirect("/?sso_error=1");
+    }
+
+    // Success → mint an operator session keyed to the verified email.
+    let session = state.sessions.create(&verified.principal.email);
+    tracing::info!(
+        target: "openpxe::saml",
+        email = %verified.principal.email,
+        idp_initiated = verified.in_response_to.is_none(),
+        "SAML SSO sign-in"
+    );
+    // safe_local_path already maps None / unsafe values to "/".
+    let relay = safe_local_path(form.relay_state.as_deref());
+    redirect_with_session(&relay, &session)
+}
+
+// ─── GET /api/sso/metadata ──────────────────────────────────────────────────
+
+pub async fn sso_metadata(State(state): State<AppState>) -> Response {
+    let cfg = state.sso.snapshot();
+    let sp = sp_params(&state, &cfg);
+    let xml = saml::metadata::build_sp_metadata(&sp);
+    (
+        StatusCode::OK,
+        [(header::CONTENT_TYPE, "application/samlmetadata+xml")],
+        xml,
+    )
+        .into_response()
+}
+
+// ─── helpers ────────────────────────────────────────────────────────────────
+
+/// Derive runtime SP parameters from config + the advertised public base URL.
+fn sp_params(state: &AppState, cfg: &SsoConfig) -> SpParams {
+    let base = state.public_base_url.trim_end_matches('/');
+    let entity_id = if cfg.entity_id.trim().is_empty() {
+        base.to_owned()
+    } else {
+        cfg.entity_id.trim().to_owned()
+    };
+    SpParams {
+        entity_id,
+        acs_url: format!("{base}/api/sso/acs"),
+    }
+}
+
+/// Resolve the IdP metadata: prefer the metadata URL (fetched + cached) per
+/// the "URL wins" rule, else parse the pasted XML.
+async fn resolve_idp_metadata(state: &AppState, cfg: &SsoConfig) -> Result<IdpMetadata, SamlError> {
+    let url = cfg.metadata_url.trim();
+    if !url.is_empty() {
+        if let Some(md) = state.saml.cached_metadata(url) {
+            return Ok(md);
+        }
+        let body = fetch_metadata(url).await?;
+        let md = IdpMetadata::parse(&body)?;
+        state.saml.cache_metadata(url.to_owned(), md.clone());
+        return Ok(md);
+    }
+    if !cfg.metadata.trim().is_empty() {
+        return IdpMetadata::parse(&cfg.metadata);
+    }
+    Err(SamlError::Metadata("no metadata source configured".into()))
+}
+
+async fn fetch_metadata(url: &str) -> Result<String, SamlError> {
+    let client = reqwest::Client::builder()
+        .timeout(METADATA_FETCH_TIMEOUT)
+        .build()
+        .map_err(|e| SamlError::Metadata(format!("http client: {e}")))?;
+    let resp = client
+        .get(url)
+        .send()
+        .await
+        .map_err(|e| SamlError::Metadata(format!("fetch {url}: {e}")))?;
+    if !resp.status().is_success() {
+        return Err(SamlError::Metadata(format!(
+            "fetch {url}: HTTP {}",
+            resp.status()
+        )));
+    }
+    resp.text()
+        .await
+        .map_err(|e| SamlError::Metadata(format!("read {url}: {e}")))
+}
+
+/// Only permit a same-site path (single leading slash) as a redirect target —
+/// blocks open-redirect / protocol-relative (`//evil.com`) abuse of RelayState.
+fn safe_local_path(p: Option<&str>) -> String {
+    match p {
+        Some(p) if p.starts_with('/') && !p.starts_with("//") => p.to_owned(),
+        _ => "/".to_owned(),
+    }
+}
+
+fn redirect(location: &str) -> Response {
+    Response::builder()
+        .status(StatusCode::FOUND)
+        .header(header::LOCATION, location)
+        .body(Body::empty())
+        .map_or_else(
+            |_| StatusCode::INTERNAL_SERVER_ERROR.into_response(),
+            IntoResponse::into_response,
+        )
+}
+
+fn redirect_with_session(location: &str, session: &str) -> Response {
+    Response::builder()
+        .status(StatusCode::FOUND)
+        .header(header::LOCATION, location)
+        .header(header::SET_COOKIE, auth::session_cookie(session))
+        .body(Body::empty())
+        .map_or_else(
+            |_| StatusCode::INTERNAL_SERVER_ERROR.into_response(),
+            IntoResponse::into_response,
+        )
+}