Adding local site settings to reject federated upvotes or downvotes. (#5038)

* Adding local site settings to reject federated upvotes or downvotes.

- Should help defend against downvote spamming instances.
- Fixes #4086

* Adding new vote mode types.

* Simpler activitypub vote check.

* Adding undo vote for failed vote mode check.

* Update crates/api_common/src/utils.rs

---------

Co-authored-by: Nutomic <me@nutomic.com>

crates/api/src/comment/like.rs

@@ -5,7 +5,7 @@ use lemmy_api_common::{
   comment::{CommentResponse, CreateCommentLike},
   context::LemmyContext,
   send_activity::{ActivityChannel, SendActivityData},
-  utils::{check_bot_account, check_community_user_action, check_downvotes_enabled},
+  utils::{check_bot_account, check_community_user_action, check_local_vote_mode, VoteItem},
 };
 use lemmy_db_schema::{
   newtypes::LocalUserId,
@@ -27,14 +27,20 @@ pub async fn like_comment(
   local_user_view: LocalUserView,
 ) -> LemmyResult<Json<CommentResponse>> {
   let local_site = LocalSite::read(&mut context.pool()).await?;
+  let comment_id = data.comment_id;
 
   let mut recipient_ids = Vec::<LocalUserId>::new();
 
-  // Don't do a downvote if site has downvotes disabled
-  check_downvotes_enabled(data.score, &local_site)?;
+  check_local_vote_mode(
+    data.score,
+    VoteItem::Comment(comment_id),
+    &local_site,
+    local_user_view.person.id,
+    &mut context.pool(),
+  )
+  .await?;
   check_bot_account(&local_user_view.person)?;
 
-  let comment_id = data.comment_id;
   let orig_comment = CommentView::read(
     &mut context.pool(),
     comment_id,

crates/api/src/post/like.rs

@@ -8,8 +8,9 @@ use lemmy_api_common::{
   utils::{
     check_bot_account,
     check_community_user_action,
-    check_downvotes_enabled,
+    check_local_vote_mode,
     mark_post_as_read,
+    VoteItem,
   },
 };
 use lemmy_db_schema::{
@@ -31,13 +32,19 @@ pub async fn like_post(
   local_user_view: LocalUserView,
 ) -> LemmyResult<Json<PostResponse>> {
   let local_site = LocalSite::read(&mut context.pool()).await?;
+  let post_id = data.post_id;
 
-  // Don't do a downvote if site has downvotes disabled
-  check_downvotes_enabled(data.score, &local_site)?;
+  check_local_vote_mode(
+    data.score,
+    VoteItem::Post(post_id),
+    &local_site,
+    local_user_view.person.id,
+    &mut context.pool(),
+  )
+  .await?;
   check_bot_account(&local_user_view.person)?;
 
   // Check for a community ban
-  let post_id = data.post_id;
   let post = Post::read(&mut context.pool(), post_id).await?;
 
   check_community_user_action(

crates/api_common/src/site.rs

@@ -21,6 +21,7 @@ use lemmy_db_schema::{
     tagline::Tagline,
   },
   CommentSortType,
+  FederationMode,
   ListingType,
   ModlogActionType,
   PostListingMode,
@@ -170,7 +171,6 @@ pub struct CreateSite {
   pub description: Option<String>,
   pub icon: Option<String>,
   pub banner: Option<String>,
-  pub enable_downvotes: Option<bool>,
   pub enable_nsfw: Option<bool>,
   pub community_creation_admin_only: Option<bool>,
   pub require_email_verification: Option<bool>,
@@ -208,6 +208,10 @@ pub struct CreateSite {
   pub registration_mode: Option<RegistrationMode>,
   pub oauth_registration: Option<bool>,
   pub content_warning: Option<String>,
+  pub post_upvotes: Option<FederationMode>,
+  pub post_downvotes: Option<FederationMode>,
+  pub comment_upvotes: Option<FederationMode>,
+  pub comment_downvotes: Option<FederationMode>,
 }
 
 #[skip_serializing_none]
@@ -224,8 +228,6 @@ pub struct EditSite {
   pub icon: Option<String>,
   /// A url for your site's banner.
   pub banner: Option<String>,
-  /// Whether to enable downvotes.
-  pub enable_downvotes: Option<bool>,
   /// Whether to enable NSFW.
   pub enable_nsfw: Option<bool>,
   /// Limits community creation to admins only.
@@ -291,13 +293,21 @@ pub struct EditSite {
   /// A list of blocked URLs
   pub blocked_urls: Option<Vec<String>>,
   pub registration_mode: Option<RegistrationMode>,
-  /// Whether or not external auth methods can auto-register users.
-  pub oauth_registration: Option<bool>,
   /// Whether to email admins for new reports.
   pub reports_email_admins: Option<bool>,
   /// If present, nsfw content is visible by default. Should be displayed by frontends/clients
   /// when the site is first opened by a user.
   pub content_warning: Option<String>,
+  /// Whether or not external auth methods can auto-register users.
+  pub oauth_registration: Option<bool>,
+  /// What kind of post upvotes your site allows.
+  pub post_upvotes: Option<FederationMode>,
+  /// What kind of post downvotes your site allows.
+  pub post_downvotes: Option<FederationMode>,
+  /// What kind of comment upvotes your site allows.
+  pub comment_upvotes: Option<FederationMode>,
+  /// What kind of comment downvotes your site allows.
+  pub comment_downvotes: Option<FederationMode>,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]

crates/api_common/src/utils.rs

@@ -13,7 +13,7 @@ use lemmy_db_schema::{
   aggregates::structs::{PersonPostAggregates, PersonPostAggregatesForm},
   newtypes::{CommentId, CommunityId, DbUrl, InstanceId, PersonId, PostId},
   source::{
-    comment::{Comment, CommentUpdateForm},
+    comment::{Comment, CommentLike, CommentUpdateForm},
     community::{Community, CommunityModerator, CommunityUpdateForm},
     community_block::CommunityBlock,
     email_verification::{EmailVerification, EmailVerificationForm},
@@ -28,12 +28,13 @@ use lemmy_db_schema::{
     password_reset_request::PasswordResetRequest,
     person::{Person, PersonUpdateForm},
     person_block::PersonBlock,
-    post::{Post, PostRead},
+    post::{Post, PostLike, PostRead},
     registration_application::RegistrationApplication,
     site::Site,
   },
-  traits::Crud,
+  traits::{Crud, Likeable},
   utils::DbPool,
+  FederationMode,
   RegistrationMode,
 };
 use lemmy_db_views::{
@@ -297,13 +298,36 @@ pub async fn check_person_instance_community_block(
   Ok(())
 }
 
-#[tracing::instrument(skip_all)]
-pub fn check_downvotes_enabled(score: i16, local_site: &LocalSite) -> LemmyResult<()> {
-  if score == -1 && !local_site.enable_downvotes {
-    Err(LemmyErrorType::DownvotesAreDisabled)?
-  } else {
-    Ok(())
+/// A vote item type used to check the vote mode.
+pub enum VoteItem {
+  Post(PostId),
+  Comment(CommentId),
 }
+
+#[tracing::instrument(skip_all)]
+pub async fn check_local_vote_mode(
+  score: i16,
+  vote_item: VoteItem,
+  local_site: &LocalSite,
+  person_id: PersonId,
+  pool: &mut DbPool<'_>,
+) -> LemmyResult<()> {
+  let (downvote_setting, upvote_setting) = match vote_item {
+    VoteItem::Post(_) => (local_site.post_downvotes, local_site.post_upvotes),
+    VoteItem::Comment(_) => (local_site.comment_downvotes, local_site.comment_upvotes),
+  };
+
+  let downvote_fail = score == -1 && downvote_setting == FederationMode::Disable;
+  let upvote_fail = score == 1 && upvote_setting == FederationMode::Disable;
+
+  // Undo previous vote for item if new vote fails
+  if downvote_fail || upvote_fail {
+    match vote_item {
+      VoteItem::Post(post_id) => PostLike::remove(pool, person_id, post_id).await?,
+      VoteItem::Comment(comment_id) => CommentLike::remove(pool, person_id, comment_id).await?,
+    };
+  }
+  Ok(())
 }
 
 /// Dont allow bots to do certain actions, like voting

crates/api_crud/src/site/create.rs

@@ -90,7 +90,6 @@ pub async fn create_site(
   let local_site_form = LocalSiteUpdateForm {
     // Set the site setup to true
     site_setup: Some(true),
-    enable_downvotes: data.enable_downvotes,
     registration_mode: data.registration_mode,
     community_creation_admin_only: data.community_creation_admin_only,
     require_email_verification: data.require_email_verification,
@@ -110,6 +109,10 @@ pub async fn create_site(
     captcha_enabled: data.captcha_enabled,
     captcha_difficulty: data.captcha_difficulty.clone(),
     default_post_listing_mode: data.default_post_listing_mode,
+    post_upvotes: data.post_upvotes,
+    post_downvotes: data.post_downvotes,
+    comment_upvotes: data.comment_upvotes,
+    comment_downvotes: data.comment_downvotes,
     ..Default::default()
   };
 

crates/api_crud/src/site/update.rs

@@ -99,7 +99,6 @@ pub async fn update_site(
     .ok();
 
   let local_site_form = LocalSiteUpdateForm {
-    enable_downvotes: data.enable_downvotes,
     registration_mode: data.registration_mode,
     community_creation_admin_only: data.community_creation_admin_only,
     require_email_verification: data.require_email_verification,
@@ -121,6 +120,10 @@ pub async fn update_site(
     reports_email_admins: data.reports_email_admins,
     default_post_listing_mode: data.default_post_listing_mode,
     oauth_registration: data.oauth_registration,
+    post_upvotes: data.post_upvotes,
+    post_downvotes: data.post_downvotes,
+    comment_upvotes: data.comment_upvotes,
+    comment_downvotes: data.comment_downvotes,
     ..Default::default()
   };
 

crates/apub/src/activities/voting/vote.rs

@@ -18,7 +18,7 @@ use activitypub_federation::{
   traits::{ActivityHandler, Actor},
 };
 use lemmy_api_common::{context::LemmyContext, utils::check_bot_account};
-use lemmy_db_schema::source::local_site::LocalSite;
+use lemmy_db_schema::{source::local_site::LocalSite, FederationMode};
 use lemmy_utils::error::{LemmyError, LemmyResult};
 use url::Url;
 
@@ -68,12 +68,22 @@ impl ActivityHandler for Vote {
 
     check_bot_account(&actor.0)?;
 
-    let enable_downvotes = LocalSite::read(&mut context.pool())
+    // Check for enabled federation votes
+    let local_site = LocalSite::read(&mut context.pool())
       .await
-      .map(|l| l.enable_downvotes)
-      .unwrap_or(true);
-    if self.kind == VoteType::Dislike && !enable_downvotes {
-      // If this is a downvote but downvotes are ignored, only undo any existing vote
+      .unwrap_or_default();
+
+    let (downvote_setting, upvote_setting) = match object {
+      PostOrComment::Post(_) => (local_site.post_downvotes, local_site.post_upvotes),
+      PostOrComment::Comment(_) => (local_site.comment_downvotes, local_site.comment_upvotes),
+    };
+
+    // Don't allow dislikes for either disabled, or local only votes
+    let downvote_fail = self.kind == VoteType::Dislike && downvote_setting != FederationMode::All;
+    let upvote_fail = self.kind == VoteType::Like && upvote_setting != FederationMode::All;
+
+    if downvote_fail || upvote_fail {
+      // If this is a rejection, undo the vote
       match object {
         PostOrComment::Post(p) => undo_vote_post(actor, &p, context).await,
         PostOrComment::Comment(c) => undo_vote_comment(actor, &c, context).await,

crates/db_schema/src/lib.rs

@@ -251,6 +251,27 @@ pub enum CommunityVisibility {
   LocalOnly,
 }
 
+#[derive(
+  EnumString, Display, Debug, Serialize, Deserialize, Clone, Copy, PartialEq, Eq, Default, Hash,
+)]
+#[cfg_attr(feature = "full", derive(DbEnum, TS))]
+#[cfg_attr(
+  feature = "full",
+  ExistingTypePath = "crate::schema::sql_types::FederationModeEnum"
+)]
+#[cfg_attr(feature = "full", DbValueStyle = "verbatim")]
+#[cfg_attr(feature = "full", ts(export))]
+/// The federation mode for an item
+pub enum FederationMode {
+  #[default]
+  /// Allows all
+  All,
+  /// Allows only local
+  Local,
+  /// Disables
+  Disable,
+}
+
 /// Wrapper for assert_eq! macro. Checks that vec matches the given length, and prints the
 /// vec on failure.
 #[macro_export]

crates/db_schema/src/schema.rs

@@ -13,6 +13,10 @@ pub mod sql_types {
     #[diesel(postgres_type(name = "community_visibility"))]
     pub struct CommunityVisibility;
 
+    #[derive(diesel::sql_types::SqlType)]
+    #[diesel(postgres_type(name = "federation_mode_enum"))]
+    pub struct FederationModeEnum;
+
     #[derive(diesel::sql_types::SqlType)]
     #[diesel(postgres_type(name = "listing_type_enum"))]
     pub struct ListingTypeEnum;
@@ -368,12 +372,12 @@ diesel::table! {
     use super::sql_types::PostListingModeEnum;
     use super::sql_types::PostSortTypeEnum;
     use super::sql_types::CommentSortTypeEnum;
+    use super::sql_types::FederationModeEnum;
 
     local_site (id) {
         id -> Int4,
         site_id -> Int4,
         site_setup -> Bool,
-        enable_downvotes -> Bool,
         community_creation_admin_only -> Bool,
         require_email_verification -> Bool,
         application_question -> Nullable<Text>,
@@ -398,6 +402,10 @@ diesel::table! {
         default_post_sort_type -> PostSortTypeEnum,
         default_comment_sort_type -> CommentSortTypeEnum,
         oauth_registration -> Bool,
+        post_upvotes -> FederationModeEnum,
+        post_downvotes -> FederationModeEnum,
+        comment_upvotes -> FederationModeEnum,
+        comment_downvotes -> FederationModeEnum,
     }
 }
 

crates/db_schema/src/source/local_site.rs

@@ -3,6 +3,7 @@ use crate::schema::local_site;
 use crate::{
   newtypes::{LocalSiteId, SiteId},
   CommentSortType,
+  FederationMode,
   ListingType,
   PostListingMode,
   PostSortType,
@@ -27,8 +28,6 @@ pub struct LocalSite {
   pub site_id: SiteId,
   /// True if the site is set up.
   pub site_setup: bool,
-  /// Whether downvotes are enabled.
-  pub enable_downvotes: bool,
   /// Whether only admins can create communities.
   pub community_creation_admin_only: bool,
   /// Whether emails are required.
@@ -72,6 +71,14 @@ pub struct LocalSite {
   pub default_comment_sort_type: CommentSortType,
   /// Whether or not external auth methods can auto-register users.
   pub oauth_registration: bool,
+  /// What kind of post upvotes your site allows.
+  pub post_upvotes: FederationMode,
+  /// What kind of post downvotes your site allows.
+  pub post_downvotes: FederationMode,
+  /// What kind of comment upvotes your site allows.
+  pub comment_upvotes: FederationMode,
+  /// What kind of comment downvotes your site allows.
+  pub comment_downvotes: FederationMode,
 }
 
 #[derive(Clone, derive_new::new)]
@@ -82,8 +89,6 @@ pub struct LocalSiteInsertForm {
   #[new(default)]
   pub site_setup: Option<bool>,
   #[new(default)]
-  pub enable_downvotes: Option<bool>,
-  #[new(default)]
   pub community_creation_admin_only: Option<bool>,
   #[new(default)]
   pub require_email_verification: Option<bool>,
@@ -114,8 +119,6 @@ pub struct LocalSiteInsertForm {
   #[new(default)]
   pub registration_mode: Option<RegistrationMode>,
   #[new(default)]
-  pub oauth_registration: Option<bool>,
-  #[new(default)]
   pub reports_email_admins: Option<bool>,
   #[new(default)]
   pub federation_signed_fetch: Option<bool>,
@@ -125,6 +128,16 @@ pub struct LocalSiteInsertForm {
   pub default_post_sort_type: Option<PostSortType>,
   #[new(default)]
   pub default_comment_sort_type: Option<CommentSortType>,
+  #[new(default)]
+  pub oauth_registration: Option<bool>,
+  #[new(default)]
+  pub post_upvotes: Option<FederationMode>,
+  #[new(default)]
+  pub post_downvotes: Option<FederationMode>,
+  #[new(default)]
+  pub comment_upvotes: Option<FederationMode>,
+  #[new(default)]
+  pub comment_downvotes: Option<FederationMode>,
 }
 
 #[derive(Clone, Default)]
@@ -132,7 +145,6 @@ pub struct LocalSiteInsertForm {
 #[cfg_attr(feature = "full", diesel(table_name = local_site))]
 pub struct LocalSiteUpdateForm {
   pub site_setup: Option<bool>,
-  pub enable_downvotes: Option<bool>,
   pub community_creation_admin_only: Option<bool>,
   pub require_email_verification: Option<bool>,
   pub application_question: Option<Option<String>>,
@@ -148,11 +160,15 @@ pub struct LocalSiteUpdateForm {
   pub captcha_enabled: Option<bool>,
   pub captcha_difficulty: Option<String>,
   pub registration_mode: Option<RegistrationMode>,
-  pub oauth_registration: Option<bool>,
   pub reports_email_admins: Option<bool>,
   pub updated: Option<Option<DateTime<Utc>>>,
   pub federation_signed_fetch: Option<bool>,
   pub default_post_listing_mode: Option<PostListingMode>,
   pub default_post_sort_type: Option<PostSortType>,
   pub default_comment_sort_type: Option<CommentSortType>,
+  pub oauth_registration: Option<bool>,
+  pub post_upvotes: Option<FederationMode>,
+  pub post_downvotes: Option<FederationMode>,
+  pub comment_upvotes: Option<FederationMode>,
+  pub comment_downvotes: Option<FederationMode>,
 }

crates/utils/src/error.rs

@@ -46,7 +46,7 @@ pub enum LemmyErrorType {
   PersonIsBlocked,
   CommunityIsBlocked,
   InstanceIsBlocked,
-  DownvotesAreDisabled,
+  VoteNotAllowed,
   InstanceIsPrivate,
   /// Password must be between 10 and 60 characters
   InvalidPassword,

migrations/2024-09-20-134838_add_federation_vote_rejection/down.sql

@@ -0,0 +1,31 @@
+-- Add back the enable_downvotes column
+ALTER TABLE local_site
+    ADD COLUMN enable_downvotes boolean DEFAULT TRUE NOT NULL;
+
+-- regenerate their values (from post_downvotes alone)
+WITH subquery AS (
+    SELECT
+        post_downvotes,
+        CASE WHEN post_downvotes = 'Disable'::federation_mode_enum THEN
+            FALSE
+        ELSE
+            TRUE
+        END
+    FROM
+        local_site)
+UPDATE
+    local_site
+SET
+    enable_downvotes = subquery.case
+FROM
+    subquery;
+
+-- Drop the new columns
+ALTER TABLE local_site
+    DROP COLUMN post_upvotes,
+    DROP COLUMN post_downvotes,
+    DROP COLUMN comment_upvotes,
+    DROP COLUMN comment_downvotes;
+
+DROP TYPE federation_mode_enum;
+

migrations/2024-09-20-134838_add_federation_vote_rejection/up.sql

@@ -0,0 +1,39 @@
+-- This removes the simple enable_downvotes setting, in favor of an
+-- expanded federation mode type for post/comment up/downvotes.
+-- Create the federation mode enum
+CREATE TYPE federation_mode_enum AS ENUM (
+    'All',
+    'Local',
+    'Disable'
+);
+
+-- Add the new columns
+ALTER TABLE local_site
+    ADD COLUMN post_upvotes federation_mode_enum DEFAULT 'All'::federation_mode_enum NOT NULL,
+    ADD COLUMN post_downvotes federation_mode_enum DEFAULT 'All'::federation_mode_enum NOT NULL,
+    ADD COLUMN comment_upvotes federation_mode_enum DEFAULT 'All'::federation_mode_enum NOT NULL,
+    ADD COLUMN comment_downvotes federation_mode_enum DEFAULT 'All'::federation_mode_enum NOT NULL;
+
+-- Copy over the enable_downvotes into the post and comment downvote settings
+WITH subquery AS (
+    SELECT
+        enable_downvotes,
+        CASE WHEN enable_downvotes = TRUE THEN
+            'All'::federation_mode_enum
+        ELSE
+            'Disable'::federation_mode_enum
+        END
+    FROM
+        local_site)
+UPDATE
+    local_site
+SET
+    post_downvotes = subquery.case,
+    comment_downvotes = subquery.case
+FROM
+    subquery;
+
+-- Drop the enable_downvotes column
+ALTER TABLE local_site
+    DROP COLUMN enable_downvotes;
+