manta_shared/common/
jwt_ops.rs

1//! JWT claim extractors used by the audit and authorization paths.
2//!
3//! Decodes a bearer token (with or without the `Bearer ` prefix),
4//! tolerates both URL-safe and standard Base64 encodings, and
5//! returns named claims as `String`. All failures map to
6//! [`MantaError::JwtMalformed`] with a structured message; the
7//! HTTP layer maps that to a 401.
8//!
9//! # Security caveat
10//!
11//! These helpers **do not verify the JWT signature**. Claims are
12//! extracted on trust. The signature is verified upstream by the
13//! backend (CSM / OpenCHAMI) on every call that uses the token, so a
14//! forged token with `pa_admin` in `realm_access.roles` will still be
15//! rejected at the first backend round-trip — but the in-process
16//! `is_user_admin` short-circuit means any code path that returns
17//! before the backend call is reached (e.g. a future cached path or
18//! a handler that only checks the local roles) would skip every
19//! group-access check.
20//!
21//! TODO: verify the signature locally against the per-site Keycloak
22//! JWKS, cached in `ServerState` with refresh on `kid` miss. Tracked
23//! as a follow-up because it requires JWKS fetching, key rotation,
24//! and a per-site cache. For now treat `is_user_admin` as advisory:
25//! never grant a privilege based on it alone without a follow-up
26//! call that hits the backend.
27
28use base64::prelude::*;
29use serde_json::Value;
30
31use crate::common::error::MantaError;
32
33/// Keycloak role name that grants full admin access. Owned here so
34/// every workspace crate that decodes JWTs can read it without
35/// pulling `manta-server` as a dependency.
36pub static PA_ADMIN: &str = "pa_admin";
37
38fn get_claims_from_jwt_token(token: &str) -> Result<Value, MantaError> {
39  // Handle both "Bearer <token>" and bare "<token>" formats
40  let jwt_body = token.split(' ').nth(1).unwrap_or(token);
41
42  let base64_claims = jwt_body.split('.').nth(1).ok_or_else(|| {
43    MantaError::JwtMalformed(
44      "expected header.payload.signature format".to_string(),
45    )
46  })?;
47
48  let claims_u8 = BASE64_URL_SAFE_NO_PAD
49    .decode(base64_claims)
50    .or_else(|_| BASE64_STANDARD.decode(base64_claims))
51    .map_err(|e| {
52      MantaError::JwtMalformed(format!("could not decode claims: {e}"))
53    })?;
54
55  let claims_str = std::str::from_utf8(&claims_u8).map_err(|e| {
56    MantaError::JwtMalformed(format!("claims are not valid UTF-8: {e}"))
57  })?;
58
59  Ok(serde_json::from_str::<Value>(claims_str)?)
60}
61
62/// Extract the `name` claim from a JWT token.
63///
64/// Returns `"MISSING"` if the claim is absent.
65///
66/// # Errors
67///
68/// Returns [`MantaError::JwtMalformed`] when `token` does not parse
69/// as `header.payload.signature` Base64, or when the payload is not
70/// valid UTF-8 JSON.
71pub fn get_name(token: &str) -> Result<String, MantaError> {
72  let jwt_claims = get_claims_from_jwt_token(token)?;
73
74  let jwt_name = jwt_claims.get("name").and_then(Value::as_str);
75
76  match jwt_name {
77    Some(name) => Ok(name.to_string()),
78    None => Ok("MISSING".to_string()),
79  }
80}
81
82/// Extract the `preferred_username` claim from a JWT token.
83///
84/// Returns `"MISSING"` if the claim is absent.
85///
86/// # Errors
87///
88/// Returns [`MantaError::JwtMalformed`] when `token` does not parse
89/// as `header.payload.signature` Base64, or when the payload is not
90/// valid UTF-8 JSON.
91pub fn get_preferred_username(token: &str) -> Result<String, MantaError> {
92  let jwt_claims = get_claims_from_jwt_token(token)?;
93
94  let jwt_preferred_username =
95    jwt_claims.get("preferred_username").and_then(Value::as_str);
96
97  match jwt_preferred_username {
98    Some(name) => Ok(name.to_string()),
99    None => Ok("MISSING".to_string()),
100  }
101}
102
103/// Extract the `realm_access.roles` claim from a JWT token.
104///
105/// Returns an empty `Vec` when the claim is absent or is not a JSON
106/// array of strings. Used by [`is_user_admin`] and (downstream) by
107/// the per-handler authorization checks in `service::authorization`
108/// inside `manta-server`.
109///
110/// # Errors
111///
112/// Returns [`MantaError::JwtMalformed`] when `token` does not parse
113/// as `header.payload.signature` Base64, or when the payload is not
114/// valid UTF-8 JSON.
115pub fn get_roles(token: &str) -> Result<Vec<String>, MantaError> {
116  // Absent claim → empty roles → not admin.
117  Ok(
118    get_claims_from_jwt_token(token)?
119      .pointer("/realm_access/roles")
120      .unwrap_or(&serde_json::json!([]))
121      .as_array()
122      .cloned()
123      .unwrap_or_default()
124      .iter()
125      .filter_map(|role_value| role_value.as_str().map(str::to_string))
126      .collect(),
127  )
128}
129
130/// Realm role string that puts the server into read-only mode for this
131/// caller. A token carrying this role is refused (`403 Forbidden`) on
132/// every mutating endpoint under `/api/v1/*` by the server's
133/// `auth_middleware::read_only_guard`.
134pub const READ_ONLY_ROLE: &str = "manta-read-only";
135
136/// Returns `true` when the token's `realm_access.roles` claim contains
137/// `role`. Any JWT-decode failure or missing claim returns `false` —
138/// callers want a yes/no answer, and downstream `BearerToken`
139/// extraction is the auth boundary that surfaces the underlying 401.
140///
141/// Used by [`is_user_admin`] and by the server's
142/// `auth_middleware::read_only_guard`.
143pub fn has_role(token: &str, role: &str) -> bool {
144  get_roles(token).is_ok_and(|roles| roles.iter().any(|r| r == role))
145}
146
147/// Returns `true` when the token's `realm_access.roles` claim
148/// contains the [`PA_ADMIN`] role. Errors decoding the JWT are
149/// swallowed and treated as "not admin".
150///
151/// Advisory only — see the module-level security caveat: this does
152/// **not** verify the signature, so a forged token is detected only
153/// at the next backend round-trip.
154pub fn is_user_admin(token: &str) -> bool {
155  has_role(token, PA_ADMIN)
156}
157
158#[cfg(test)]
159mod tests {
160  use super::*;
161
162  /// Build a fake JWT with the given JSON payload.
163  fn make_jwt(payload: &serde_json::Value) -> String {
164    let header = BASE64_URL_SAFE_NO_PAD.encode(r#"{"alg":"none","typ":"JWT"}"#);
165    let body = BASE64_URL_SAFE_NO_PAD.encode(payload.to_string());
166    format!("{header}.{body}.sig")
167  }
168
169  // ---- get_name ----
170
171  #[test]
172  fn get_name_present() {
173    let token = make_jwt(&serde_json::json!({
174      "name": "Alice Smith",
175      "preferred_username": "alice"
176    }));
177    assert_eq!(get_name(&token).unwrap(), "Alice Smith");
178  }
179
180  #[test]
181  fn get_name_missing_returns_missing() {
182    let token = make_jwt(&serde_json::json!({
183      "preferred_username": "alice"
184    }));
185    assert_eq!(get_name(&token).unwrap(), "MISSING");
186  }
187
188  #[test]
189  fn get_name_with_bearer_prefix() {
190    let token = make_jwt(&serde_json::json!({
191      "name": "Bob Jones"
192    }));
193    let bearer_token = format!("Bearer {token}");
194    assert_eq!(get_name(&bearer_token).unwrap(), "Bob Jones");
195  }
196
197  // ---- get_preferred_username ----
198
199  #[test]
200  fn get_preferred_username_present() {
201    let token = make_jwt(&serde_json::json!({
202      "name": "Alice",
203      "preferred_username": "alice123"
204    }));
205    assert_eq!(get_preferred_username(&token).unwrap(), "alice123");
206  }
207
208  #[test]
209  fn get_preferred_username_missing_returns_missing() {
210    let token = make_jwt(&serde_json::json!({"name": "Alice"}));
211    assert_eq!(get_preferred_username(&token).unwrap(), "MISSING");
212  }
213
214  // ---- get_claims_from_jwt_token ----
215
216  #[test]
217  fn malformed_jwt_no_dots() {
218    assert!(get_claims_from_jwt_token("nodots").is_err());
219  }
220
221  #[test]
222  fn malformed_jwt_invalid_base64() {
223    assert!(get_claims_from_jwt_token("header.!!!invalid.sig").is_err());
224  }
225
226  #[test]
227  fn jwt_with_standard_base64_padding() {
228    // Some JWTs use standard base64 with padding
229    let payload = serde_json::json!({"name": "Test"});
230    let header = BASE64_STANDARD.encode(r#"{"alg":"none"}"#);
231    let body = BASE64_STANDARD.encode(payload.to_string());
232    let token = format!("{header}.{body}.sig");
233    assert_eq!(get_name(&token).unwrap(), "Test");
234  }
235
236  #[test]
237  fn empty_token_string_is_err() {
238    assert!(get_claims_from_jwt_token("").is_err());
239  }
240
241  #[test]
242  fn jwt_with_valid_base64_but_invalid_json() {
243    // base64 of "not json at all"
244    let body = BASE64_URL_SAFE_NO_PAD.encode("not json at all");
245    let token = format!("header.{body}.sig");
246    assert!(get_claims_from_jwt_token(&token).is_err());
247  }
248
249  #[test]
250  fn jwt_with_valid_base64_but_invalid_utf8() {
251    // Raw bytes that aren't valid UTF-8
252    let body = BASE64_URL_SAFE_NO_PAD.encode([0xFF, 0xFE, 0xFD]);
253    let token = format!("header.{body}.sig");
254    assert!(get_claims_from_jwt_token(&token).is_err());
255  }
256
257  #[test]
258  fn get_name_with_empty_string_name() {
259    let token = make_jwt(&serde_json::json!({"name": ""}));
260    assert_eq!(get_name(&token).unwrap(), "");
261  }
262
263  #[test]
264  fn bearer_prefix_with_extra_spaces() {
265    // "Bearer  token" - the split(' ').nth(1) would get empty string
266    let token = make_jwt(&serde_json::json!({"name": "Test"}));
267    let bad_bearer = format!("Bearer  {token}");
268    // nth(1) returns empty string, which has no dots -> error
269    assert!(get_name(&bad_bearer).is_err());
270  }
271
272  // ---- has_role / READ_ONLY_ROLE ----
273
274  #[test]
275  fn has_role_finds_role_when_present() {
276    let token = make_jwt(&serde_json::json!({
277      "realm_access": { "roles": ["other-role", "manta-read-only"] }
278    }));
279    assert!(has_role(&token, READ_ONLY_ROLE));
280  }
281
282  #[test]
283  fn has_role_returns_false_when_role_absent() {
284    let token = make_jwt(&serde_json::json!({
285      "realm_access": { "roles": ["other-role"] }
286    }));
287    assert!(!has_role(&token, READ_ONLY_ROLE));
288  }
289
290  #[test]
291  fn has_role_returns_false_on_missing_realm_access() {
292    let token = make_jwt(&serde_json::json!({ "name": "Alice" }));
293    assert!(!has_role(&token, READ_ONLY_ROLE));
294  }
295
296  #[test]
297  fn has_role_returns_false_on_empty_roles_array() {
298    let token = make_jwt(&serde_json::json!({
299      "realm_access": { "roles": [] }
300    }));
301    assert!(!has_role(&token, READ_ONLY_ROLE));
302  }
303
304  #[test]
305  fn has_role_returns_false_on_malformed_jwt() {
306    assert!(!has_role("not.a.jwt", READ_ONLY_ROLE));
307    assert!(!has_role("only-two.dots", READ_ONLY_ROLE));
308    assert!(!has_role("", READ_ONLY_ROLE));
309  }
310
311  #[test]
312  fn has_role_with_bearer_prefix() {
313    let token = make_jwt(&serde_json::json!({
314      "realm_access": { "roles": ["manta-read-only"] }
315    }));
316    let bearer_token = format!("Bearer {token}");
317    assert!(has_role(&bearer_token, READ_ONLY_ROLE));
318  }
319
320  #[test]
321  fn has_role_can_check_any_role_string() {
322    // The helper is generic — used by `is_user_admin` too. Pin that
323    // the role-string parameter is what's actually compared.
324    let token = make_jwt(&serde_json::json!({
325      "realm_access": { "roles": ["pa_admin"] }
326    }));
327    assert!(has_role(&token, "pa_admin"));
328    assert!(!has_role(&token, "manta-read-only"));
329  }
330
331  #[test]
332  fn read_only_role_constant_is_expected_string() {
333    // Pin the exact wire string so a rename is a deliberate breaking change.
334    assert_eq!(READ_ONLY_ROLE, "manta-read-only");
335  }
336}
manta_shared/common/jwt_ops.rs

manta_shared/common/
jwt_ops.rs
