| 1 | //! OAuth 2.1 authorization for applications, such as MCP clients, that sign |
| 2 | //! a person in through their browser: authorization code with PKCE, and |
| 3 | //! rotating refresh tokens. |
| 4 | //! |
| 5 | //! This service issues and redeems codes and tokens. Who the client is and |
| 6 | //! where it may be redirected is decided by the callers: the site, which |
| 7 | //! shows the consent page, and the API, which serves the token endpoint. |
| 8 | |
| 9 | use base64::Engine; |
| 10 | use base64::engine::general_purpose::URL_SAFE_NO_PAD; |
| 11 | use g1t_contracts::identity::*; |
| 12 | use g1t_contracts::time::{SQL_NOW, rfc3339, sql_after}; |
| 13 | use g1t_contracts::scopes::FULL_ACCESS; |
| 14 | use g1t_contracts::{FailureCode, Outcome, User, new_id}; |
| 15 | use worker::wasm_bindgen::JsValue; |
| 16 | use g1t_kit::now_ms; |
| 17 | use serde::Deserialize; |
| 18 | use sha2::{Digest, Sha256}; |
| 19 | use worker::Result; |
| 20 | |
| 21 | use crate::tokens::{Grant, stored_scopes}; |
| 22 | use crate::{Identity, crypto}; |
| 23 | |
| 24 | const CODE_TTL_SECONDS: u64 = 5 * 60; |
| 25 | const ACCESS_TTL_SECONDS: u64 = 30 * 24 * 60 * 60; |
| 26 | const REFRESH_TTL_SECONDS: u64 = 180 * 24 * 60 * 60; |
| 27 | const REFRESH_PREFIX: &str = "g1r_"; |
| 28 | |
| 29 | #[derive(Deserialize)] |
| 30 | struct CodeRow { |
| 31 | user_id: String, |
| 32 | client_id: String, |
| 33 | client_name: String, |
| 34 | redirect_uri: String, |
| 35 | code_challenge: String, |
| 36 | scopes: Option<String>, |
| 37 | } |
| 38 | |
| 39 | #[derive(Deserialize)] |
| 40 | struct GrantRow { |
| 41 | id: String, |
| 42 | user_id: String, |
| 43 | client_id: String, |
| 44 | client_name: String, |
| 45 | access_token_id: Option<String>, |
| 46 | scopes: Option<String>, |
| 47 | } |
| 48 | |
| 49 | #[derive(Deserialize)] |
| 50 | struct GrantListRow { |
| 51 | id: String, |
| 52 | client_name: String, |
| 53 | created_at: String, |
| 54 | last_used_at: String, |
| 55 | scopes: Option<String>, |
| 56 | } |
| 57 | |
| 58 | fn text(value: Option<&str>) -> JsValue { |
| 59 | value.map_or(JsValue::NULL, JsValue::from) |
| 60 | } |
| 61 | |
| 62 | /// Whether `verifier` is the secret behind an S256 `challenge` (RFC 7636). |
| 63 | fn pkce_matches(verifier: &str, challenge: &str) -> bool { |
| 64 | URL_SAFE_NO_PAD.encode(Sha256::digest(verifier.as_bytes())) == challenge |
| 65 | } |
| 66 | |
| 67 | fn invalid_grant<T>(message: &str) -> Outcome<T> { |
| 68 | Outcome::fail(FailureCode::Invalid, message) |
| 69 | } |
| 70 | |
| 71 | fn grant(row: GrantListRow) -> OAuthGrant { |
| 72 | let (scopes, legacy) = stored_scopes(row.scopes.as_deref()); |
| 73 | OAuthGrant { |
| 74 | id: row.id, |
| 75 | client_name: row.client_name, |
| 76 | created_at: row.created_at, |
| 77 | last_used_at: row.last_used_at, |
| 78 | scopes, |
| 79 | legacy, |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | impl Identity { |
| 84 | /// Records that `user` approved the client and returns the one-time |
| 85 | /// code the client exchanges for tokens. |
| 86 | pub async fn oauth_authorize(&self, a: OAuthAuthorizeArgs) -> Result<OAuthCode> { |
| 87 | let code = crypto::random_hex(32); |
| 88 | // What the person granted, carried through the code to the grant. |
| 89 | let grant = Grant::asked(&a.scopes); |
| 90 | self.db |
| 91 | .prepare(format!( |
| 92 | "INSERT INTO oauth_codes |
| 93 | (id, user_id, client_id, client_name, redirect_uri, code_challenge, expires_at, |
| 94 | scopes) |
| 95 | VALUES (?, ?, ?, ?, ?, ?, {}, ?)", |
| 96 | sql_after(CODE_TTL_SECONDS) |
| 97 | )) |
| 98 | .bind(&[ |
| 99 | crypto::sha256_hex(&code).into(), |
| 100 | a.user.id.into(), |
| 101 | a.client_id.into(), |
| 102 | a.client_name.into(), |
| 103 | a.redirect_uri.into(), |
| 104 | a.code_challenge.into(), |
| 105 | grant.scopes_column().into(), |
| 106 | ])? |
| 107 | .run() |
| 108 | .await?; |
| 109 | Ok(OAuthCode { code }) |
| 110 | } |
| 111 | |
| 112 | /// Redeems an authorization code. A code works once, only for the client |
| 113 | /// and redirect it was issued to, and only with the PKCE verifier. |
| 114 | pub async fn oauth_exchange(&self, a: OAuthExchangeArgs) -> Result<Outcome<OAuthTokens>> { |
| 115 | let id = crypto::sha256_hex(&a.code); |
| 116 | let row = self |
| 117 | .db |
| 118 | .prepare(format!( |
| 119 | "DELETE FROM oauth_codes WHERE id = ? AND expires_at > {SQL_NOW} |
| 120 | RETURNING user_id, client_id, client_name, redirect_uri, code_challenge, scopes" |
| 121 | )) |
| 122 | .bind(&[id.into()])? |
| 123 | .first::<CodeRow>(None) |
| 124 | .await?; |
| 125 | let Some(row) = row else { |
| 126 | return Ok(invalid_grant( |
| 127 | "That code is not valid, has expired, or was already used.", |
| 128 | )); |
| 129 | }; |
| 130 | if row.client_id != a.client_id || row.redirect_uri != a.redirect_uri { |
| 131 | return Ok(invalid_grant("That code was issued to a different client.")); |
| 132 | } |
| 133 | if !pkce_matches(&a.code_verifier, &row.code_challenge) { |
| 134 | return Ok(invalid_grant("The code verifier does not match.")); |
| 135 | } |
| 136 | let now = now_ms(); |
| 137 | let grant_id = new_id("oag", now); |
| 138 | self.db |
| 139 | .prepare( |
| 140 | "INSERT INTO oauth_grants |
| 141 | (id, user_id, client_id, client_name, created_at, last_used_at, scopes) |
| 142 | VALUES (?, ?, ?, ?, ?, ?, ?)", |
| 143 | ) |
| 144 | .bind(&[ |
| 145 | grant_id.as_str().into(), |
| 146 | row.user_id.as_str().into(), |
| 147 | row.client_id.into(), |
| 148 | row.client_name.as_str().into(), |
| 149 | rfc3339(now).into(), |
| 150 | rfc3339(now).into(), |
| 151 | text(row.scopes.as_deref()), |
| 152 | ])? |
| 153 | .run() |
| 154 | .await?; |
| 155 | self.log_security(&row.user_id, "oauth_grant_created", Some(&row.client_name), None).await; |
| 156 | if let Some(person) = self |
| 157 | .find_public_user("SELECT id, username, email_verified_at IS NOT NULL AS verified FROM users WHERE id = ?", &row.user_id) |
| 158 | .await? |
| 159 | { |
| 160 | self.audit_account(&person, "oauth_grant.created", &format!("Authorized the application {}", row.client_name)).await; |
| 161 | } |
| 162 | Ok(Outcome::Ok( |
| 163 | self.issue_oauth_tokens( |
| 164 | &grant_id, |
| 165 | &row.user_id, |
| 166 | &row.client_name, |
| 167 | row.scopes.as_deref(), |
| 168 | ) |
| 169 | .await?, |
| 170 | )) |
| 171 | } |
| 172 | |
| 173 | /// Trades a refresh token for new tokens. The refresh token and the |
| 174 | /// access token issued with it stop working. |
| 175 | pub async fn oauth_refresh(&self, a: OAuthRefreshArgs) -> Result<Outcome<OAuthTokens>> { |
| 176 | let row = self |
| 177 | .db |
| 178 | .prepare(format!( |
| 179 | "SELECT id, user_id, client_id, client_name, access_token_id, scopes |
| 180 | FROM oauth_grants |
| 181 | WHERE refresh_hash = ? AND expires_at > {SQL_NOW}" |
| 182 | )) |
| 183 | .bind(&[crypto::sha256_hex(&a.refresh_token).into()])? |
| 184 | .first::<GrantRow>(None) |
| 185 | .await?; |
| 186 | let Some(row) = row.filter(|row| row.client_id == a.client_id) else { |
| 187 | return Ok(invalid_grant( |
| 188 | "That refresh token is not valid or has expired. Sign in again.", |
| 189 | )); |
| 190 | }; |
| 191 | if let Some(previous) = &row.access_token_id { |
| 192 | self.db |
| 193 | .prepare("DELETE FROM access_tokens WHERE id = ?") |
| 194 | .bind(&[previous.as_str().into()])? |
| 195 | .run() |
| 196 | .await?; |
| 197 | } |
| 198 | // A refreshed token keeps what the grant allows now. |
| 199 | Ok(Outcome::Ok( |
| 200 | self.issue_oauth_tokens( |
| 201 | &row.id, |
| 202 | &row.user_id, |
| 203 | &row.client_name, |
| 204 | row.scopes.as_deref(), |
| 205 | ) |
| 206 | .await?, |
| 207 | )) |
| 208 | } |
| 209 | |
| 210 | /// A new access token and refresh token for a grant. |
| 211 | /// `scopes` is the grant's column: a grant made before scopes (null) |
| 212 | /// keeps full access. |
| 213 | async fn issue_oauth_tokens( |
| 214 | &self, |
| 215 | grant_id: &str, |
| 216 | user_id: &str, |
| 217 | client_name: &str, |
| 218 | scopes: Option<&str>, |
| 219 | ) -> Result<OAuthTokens> { |
| 220 | let (scopes, _) = stored_scopes(scopes); |
| 221 | let access = self |
| 222 | .create_access_token(CreateAccessTokenArgs { |
| 223 | user: User { |
| 224 | id: user_id.to_owned(), |
| 225 | ..User::default() |
| 226 | }, |
| 227 | name: client_name.to_owned(), |
| 228 | ttl_seconds: Some(ACCESS_TTL_SECONDS), |
| 229 | scopes: scopes.clone(), |
| 230 | listed: false, |
| 231 | }) |
| 232 | .await?; |
| 233 | let refresh_token = format!("{REFRESH_PREFIX}{}", crypto::random_hex(32)); |
| 234 | self.db |
| 235 | .prepare(format!( |
| 236 | "UPDATE oauth_grants |
| 237 | SET refresh_hash = ?, access_token_id = ?, last_used_at = {SQL_NOW}, |
| 238 | expires_at = {} |
| 239 | WHERE id = ?", |
| 240 | sql_after(REFRESH_TTL_SECONDS) |
| 241 | )) |
| 242 | .bind(&[ |
| 243 | crypto::sha256_hex(&refresh_token).into(), |
| 244 | access.info.id.into(), |
| 245 | grant_id.into(), |
| 246 | ])? |
| 247 | .run() |
| 248 | .await?; |
| 249 | Ok(OAuthTokens { |
| 250 | access_token: access.token, |
| 251 | refresh_token, |
| 252 | expires_in: ACCESS_TTL_SECONDS, |
| 253 | scope: Some(scopes.map_or_else(|| FULL_ACCESS.to_owned(), |scopes| scopes.join(" "))), |
| 254 | }) |
| 255 | } |
| 256 | |
| 257 | /// Applications the user has signed in to, most recently used first. |
| 258 | pub async fn list_oauth_grants(&self, a: UserArgs) -> Result<Vec<OAuthGrant>> { |
| 259 | let rows = self |
| 260 | .db |
| 261 | .prepare(format!( |
| 262 | "SELECT id, client_name, created_at, last_used_at, scopes FROM oauth_grants |
| 263 | WHERE user_id = ? AND expires_at > {SQL_NOW} ORDER BY last_used_at DESC" |
| 264 | )) |
| 265 | .bind(&[a.user.id.into()])? |
| 266 | .all() |
| 267 | .await? |
| 268 | .results::<GrantListRow>()?; |
| 269 | Ok(rows.into_iter().map(grant).collect()) |
| 270 | } |
| 271 | |
| 272 | /// Changes what an application may do: its current access token at |
| 273 | /// once, and every token it is given from now on. |
| 274 | pub async fn update_oauth_grant(&self, a: UpdateOAuthGrantArgs) -> Result<Outcome<OAuthGrant>> { |
| 275 | let scopes = Grant::asked(&a.scopes).scopes_column(); |
| 276 | let row = self |
| 277 | .db |
| 278 | .prepare(format!( |
| 279 | "UPDATE oauth_grants SET scopes = ? |
| 280 | WHERE id = ? AND user_id = ? AND expires_at > {SQL_NOW} |
| 281 | RETURNING id, client_name, created_at, last_used_at, scopes" |
| 282 | )) |
| 283 | .bind(&[ |
| 284 | scopes.as_str().into(), |
| 285 | a.id.as_str().into(), |
| 286 | a.user.id.as_str().into(), |
| 287 | ])? |
| 288 | .first::<GrantListRow>(None) |
| 289 | .await?; |
| 290 | let Some(row) = row else { |
| 291 | return Ok(Outcome::fail(FailureCode::NotFound, "No such application.")); |
| 292 | }; |
| 293 | self.db |
| 294 | .prepare( |
| 295 | "UPDATE access_tokens SET scopes = ? |
| 296 | WHERE id = (SELECT access_token_id FROM oauth_grants WHERE id = ?)", |
| 297 | ) |
| 298 | .bind(&[scopes.as_str().into(), a.id.as_str().into()])? |
| 299 | .run() |
| 300 | .await?; |
| 301 | self.log_security(&a.user.id, "oauth_grant_rescoped", Some(&row.client_name), None).await; |
| 302 | self.audit_account(&a.user, "oauth_grant.rescoped", &format!("Changed what the application {} may do", row.client_name)).await; |
| 303 | Ok(Outcome::Ok(grant(row))) |
| 304 | } |
| 305 | |
| 306 | /// Signs an application out: its refresh token and access token stop |
| 307 | /// working. |
| 308 | pub async fn revoke_oauth_grant(&self, a: RemoveArgs) -> Result<()> { |
| 309 | let client: Option<String> = self |
| 310 | .db |
| 311 | .prepare("SELECT client_name FROM oauth_grants WHERE id = ? AND user_id = ?") |
| 312 | .bind(&[a.id.as_str().into(), a.user.id.as_str().into()])? |
| 313 | .first(Some("client_name")) |
| 314 | .await?; |
| 315 | if let Some(client) = &client { |
| 316 | self.log_security(&a.user.id, "oauth_grant_revoked", Some(client), None).await; |
| 317 | self.audit_account(&a.user, "oauth_grant.revoked", &format!("Revoked the application {client}")).await; |
| 318 | } |
| 319 | self.db |
| 320 | .batch(vec![ |
| 321 | self.db |
| 322 | .prepare( |
| 323 | "DELETE FROM access_tokens WHERE id = |
| 324 | (SELECT access_token_id FROM oauth_grants WHERE id = ? AND user_id = ?)", |
| 325 | ) |
| 326 | .bind(&[a.id.as_str().into(), a.user.id.as_str().into()])?, |
| 327 | self.db |
| 328 | .prepare("DELETE FROM oauth_grants WHERE id = ? AND user_id = ?") |
| 329 | .bind(&[a.id.as_str().into(), a.user.id.as_str().into()])?, |
| 330 | ]) |
| 331 | .await?; |
| 332 | Ok(()) |
| 333 | } |
| 334 | } |
| 335 | |
| 336 | #[cfg(test)] |
| 337 | mod tests { |
| 338 | use super::pkce_matches; |
| 339 | |
| 340 | #[test] |
| 341 | fn pkce_verifier_matches_its_challenge() { |
| 342 | // The example from RFC 7636, appendix B. |
| 343 | let verifier = "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk"; |
| 344 | let challenge = "E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM"; |
| 345 | assert!(pkce_matches(verifier, challenge)); |
| 346 | assert!(!pkce_matches("something else", challenge)); |
| 347 | } |
| 348 | } |