feat: add PKCE

crates/api_common/src/oauth_provider.rs

@@ -25,6 +25,8 @@ pub struct CreateOAuthProvider {
   #[cfg_attr(feature = "full", ts(optional))]
   pub account_linking_enabled: Option<bool>,
   #[cfg_attr(feature = "full", ts(optional))]
+  pub use_pkce: Option<bool>,
+  #[cfg_attr(feature = "full", ts(optional))]
   pub enabled: Option<bool>,
 }
 
@@ -54,6 +56,8 @@ pub struct EditOAuthProvider {
   #[cfg_attr(feature = "full", ts(optional))]
   pub account_linking_enabled: Option<bool>,
   #[cfg_attr(feature = "full", ts(optional))]
+  pub use_pkce: Option<bool>,
+  #[cfg_attr(feature = "full", ts(optional))]
   pub enabled: Option<bool>,
 }
 
@@ -72,6 +76,7 @@ pub struct DeleteOAuthProvider {
 /// Logging in with an OAuth 2.0 authorization
 pub struct AuthenticateWithOauth {
   pub code: String,
+  pub pkce_code_verifier: Option<String>,
   pub oauth_provider_id: OAuthProviderId,
   pub redirect_uri: Url,
   #[cfg_attr(feature = "full", ts(optional))]

crates/api_common/src/utils.rs

@@ -1162,6 +1162,19 @@ fn build_proxied_image_url(
   ))
 }
 
+pub fn check_code_verifier(code_verifier: &str) -> LemmyResult<&str> {
+  static VALID_CODE_VERIFIER_REGEX: LazyLock<Regex> =
+    LazyLock::new(|| Regex::new(r"^[a-zA-Z0-9\-._~]{43,128}$").expect("compile regex"));
+
+  let check = VALID_CODE_VERIFIER_REGEX.is_match(code_verifier);
+
+  if !check {
+    Err(LemmyErrorType::InvalidCodeVerifier.into())
+  } else {
+    Ok(code_verifier)
+  }
+}
+
 #[cfg(test)]
 mod tests {
 

crates/api_crud/src/oauth_provider/create.rs

@@ -35,6 +35,7 @@ pub async fn create_oauth_provider(
     scopes: data.scopes.to_string(),
     auto_verify_email: data.auto_verify_email,
     account_linking_enabled: data.account_linking_enabled,
+    use_pkce: data.use_pkce,
     enabled: data.enabled,
   };
   let oauth_provider = OAuthProvider::create(&mut context.pool(), &oauth_provider_form).await?;

crates/api_crud/src/oauth_provider/update.rs

@@ -32,6 +32,7 @@ pub async fn update_oauth_provider(
     auto_verify_email: data.auto_verify_email,
     account_linking_enabled: data.account_linking_enabled,
     enabled: data.enabled,
+    use_pkce: data.use_pkce,
     updated: Some(Some(naive_now())),
   };
 

crates/api_crud/src/user/create.rs

@@ -6,6 +6,7 @@ use lemmy_api_common::{
   oauth_provider::AuthenticateWithOauth,
   person::{LoginResponse, Register},
   utils::{
+    check_code_verifier,
     check_email_verified,
     check_registration_application,
     check_user_valid,
@@ -228,9 +229,20 @@ pub async fn authenticate_with_oauth(
     return Err(LemmyErrorType::OauthAuthorizationInvalid)?;
   }
 
-  let token_response =
-    oauth_request_access_token(&context, &oauth_provider, &data.code, redirect_uri.as_str())
-      .await?;
+  let pkce_code_verifier = data
+    .pkce_code_verifier
+    .as_deref()
+    .map(check_code_verifier)
+    .transpose()?;
+
+  let token_response = oauth_request_access_token(
+    &context,
+    &oauth_provider,
+    &data.code,
+    pkce_code_verifier,
+    redirect_uri.as_str(),
+  )
+  .await?;
 
   let user_info = oidc_get_user_info(
     &context,
@@ -509,20 +521,26 @@ async fn oauth_request_access_token(
   context: &Data<LemmyContext>,
   oauth_provider: &OAuthProvider,
   code: &str,
+  pkce_code_verifier: Option<&str>,
   redirect_uri: &str,
 ) -> LemmyResult<TokenResponse> {
+  let mut form = vec![
+    ("grant_type", "authorization_code"),
+    ("code", code),
+    ("redirect_uri", redirect_uri),
+    ("client_id", &oauth_provider.client_id),
+    ("client_secret", &oauth_provider.client_secret),
+  ];
+  if let Some(code_verifier) = pkce_code_verifier {
+    form.push(("code_verifier", code_verifier));
+  }
+
   // Request an Access Token from the OAUTH provider
   let response = context
     .client()
     .post(oauth_provider.token_endpoint.as_str())
     .header("Accept", "application/json")
-    .form(&[
-      ("grant_type", "authorization_code"),
-      ("code", code),
-      ("redirect_uri", redirect_uri),
-      ("client_id", &oauth_provider.client_id),
-      ("client_secret", &oauth_provider.client_secret),
-    ])
+    .form(&*form)
     .send()
     .await;
 

crates/db_schema/src/schema.rs

@@ -631,6 +631,7 @@ diesel::table! {
         scopes -> Text,
         auto_verify_email -> Bool,
         account_linking_enabled -> Bool,
+        use_pkce -> Bool,
         enabled -> Bool,
         published -> Timestamptz,
         updated -> Nullable<Timestamptz>,

crates/db_schema/src/source/oauth_provider.rs

@@ -57,6 +57,8 @@ pub struct OAuthProvider {
   pub auto_verify_email: bool,
   /// Allows linking an OAUTH account to an existing user account by matching emails
   pub account_linking_enabled: bool,
+  /// switch to enable or disable PKCE
+  pub use_pkce: bool,
   /// switch to enable or disable an oauth provider
   pub enabled: bool,
   pub published: DateTime<Utc>,
@@ -83,6 +85,7 @@ impl Serialize for PublicOAuthProvider {
     state.serialize_field("authorization_endpoint", &self.0.authorization_endpoint)?;
     state.serialize_field("client_id", &self.0.client_id)?;
     state.serialize_field("scopes", &self.0.scopes)?;
+    state.serialize_field("use_pkce", &self.0.use_pkce)?;
     state.end()
   }
 }
@@ -102,6 +105,7 @@ pub struct OAuthProviderInsertForm {
   pub scopes: String,
   pub auto_verify_email: Option<bool>,
   pub account_linking_enabled: Option<bool>,
+  pub use_pkce: Option<bool>,
   pub enabled: Option<bool>,
 }
 
@@ -118,6 +122,7 @@ pub struct OAuthProviderUpdateForm {
   pub scopes: Option<String>,
   pub auto_verify_email: Option<bool>,
   pub account_linking_enabled: Option<bool>,
+  pub use_pkce: Option<bool>,
   pub enabled: Option<bool>,
   pub updated: Option<Option<DateTime<Utc>>>,
 }

crates/utils/src/error.rs

@@ -76,6 +76,7 @@ pub enum LemmyErrorType {
   MissingAnEmail,
   RateLimitError,
   InvalidName,
+  InvalidCodeVerifier,
   InvalidDisplayName,
   InvalidMatrixId,
   InvalidPostTitle,

migrations/2024-11-12-080606_oauth_pkce/down.sql

@@ -0,0 +1,3 @@
+ALTER TABLE oauth_provider
+    DROP COLUMN use_pkce;
+

migrations/2024-11-12-080606_oauth_pkce/up.sql

@@ -0,0 +1,3 @@
+ALTER TABLE oauth_provider
+    ADD COLUMN use_pkce boolean DEFAULT FALSE NOT NULL;
+