From 1c4ae8d268dc58829b5114ac2f0441c6f72e499d Mon Sep 17 00:00:00 2001
From: Matthias Ahouansou <matthias@ahouansou.cz>
Date: Wed, 24 Apr 2024 09:28:16 +0100
Subject: [PATCH] fix(redaction): use content.redacts when checking v11 events

---
 src/service/rooms/event_handler/mod.rs | 60 ++++++++++++++++++-----
 src/service/rooms/timeline/mod.rs      | 68 ++++++++++++++++++++------
 2 files changed, 102 insertions(+), 26 deletions(-)

diff --git a/src/service/rooms/event_handler/mod.rs b/src/service/rooms/event_handler/mod.rs
index ada289fb..b7817e50 100644
--- a/src/service/rooms/event_handler/mod.rs
+++ b/src/service/rooms/event_handler/mod.rs
@@ -23,7 +23,10 @@ use ruma::{
         },
     },
     events::{
-        room::{create::RoomCreateEventContent, server_acl::RoomServerAclEventContent},
+        room::{
+            create::RoomCreateEventContent, redaction::RoomRedactionEventContent,
+            server_acl::RoomServerAclEventContent,
+        },
         StateEventType, TimelineEventType,
     },
     int,
@@ -797,17 +800,50 @@ impl Service {
             |k, s| auth_events.get(&(k.clone(), s.to_owned())),
         )
         .map_err(|_e| Error::BadRequest(ErrorKind::InvalidParam, "Auth check failed."))?
-            || if let Some(redact_id) = &incoming_pdu.redacts {
-                incoming_pdu.kind == TimelineEventType::RoomRedaction
-                    && !services().rooms.state_accessor.user_can_redact(
-                        redact_id,
-                        &incoming_pdu.sender,
-                        &incoming_pdu.room_id,
-                        true,
-                    )?
-            } else {
-                false
-            };
+            || incoming_pdu.kind == TimelineEventType::RoomRedaction
+                && match room_version_id {
+                    RoomVersionId::V1
+                    | RoomVersionId::V2
+                    | RoomVersionId::V3
+                    | RoomVersionId::V4
+                    | RoomVersionId::V5
+                    | RoomVersionId::V6
+                    | RoomVersionId::V7
+                    | RoomVersionId::V8
+                    | RoomVersionId::V9
+                    | RoomVersionId::V10 => {
+                        if let Some(redact_id) = &incoming_pdu.redacts {
+                            !services().rooms.state_accessor.user_can_redact(
+                                redact_id,
+                                &incoming_pdu.sender,
+                                &incoming_pdu.room_id,
+                                true,
+                            )?
+                        } else {
+                            false
+                        }
+                    }
+                    RoomVersionId::V11 => {
+                        let content = serde_json::from_str::<RoomRedactionEventContent>(
+                            incoming_pdu.content.get(),
+                        )
+                        .map_err(|_| Error::bad_database("Invalid content in redaction pdu."))?;
+
+                        if let Some(redact_id) = &content.redacts {
+                            !services().rooms.state_accessor.user_can_redact(
+                                redact_id,
+                                &incoming_pdu.sender,
+                                &incoming_pdu.room_id,
+                                true,
+                            )?
+                        } else {
+                            false
+                        }
+                    }
+                    _ => {
+                        unreachable!("Validity of room version already checked")
+                    }
+                };
 
         // 13. Use state resolution to find new room state
 
diff --git a/src/service/rooms/timeline/mod.rs b/src/service/rooms/timeline/mod.rs
index 2752abe4..acb00d01 100644
--- a/src/service/rooms/timeline/mod.rs
+++ b/src/service/rooms/timeline/mod.rs
@@ -900,21 +900,61 @@ impl Service {
         }
 
         // If redaction event is not authorized, do not append it to the timeline
-        if let Some(redact_id) = &pdu.redacts {
-            if pdu.kind == TimelineEventType::RoomRedaction
-                && !services().rooms.state_accessor.user_can_redact(
-                    redact_id,
-                    &pdu.sender,
-                    &pdu.room_id,
-                    false,
-                )?
-            {
-                return Err(Error::BadRequest(
-                    ErrorKind::Forbidden,
-                    "User cannot redact this event.",
-                ));
+        if pdu.kind == TimelineEventType::RoomRedaction {
+            match services().rooms.state.get_room_version(&pdu.room_id)? {
+                RoomVersionId::V1
+                | RoomVersionId::V2
+                | RoomVersionId::V3
+                | RoomVersionId::V4
+                | RoomVersionId::V5
+                | RoomVersionId::V6
+                | RoomVersionId::V7
+                | RoomVersionId::V8
+                | RoomVersionId::V9
+                | RoomVersionId::V10 => {
+                    if let Some(redact_id) = &pdu.redacts {
+                        if !services().rooms.state_accessor.user_can_redact(
+                            redact_id,
+                            &pdu.sender,
+                            &pdu.room_id,
+                            false,
+                        )? {
+                            return Err(Error::BadRequest(
+                                ErrorKind::Forbidden,
+                                "User cannot redact this event.",
+                            ));
+                        }
+                    };
+                }
+                RoomVersionId::V11 => {
+                    let content =
+                        serde_json::from_str::<RoomRedactionEventContent>(pdu.content.get())
+                            .map_err(|_| {
+                                Error::bad_database("Invalid content in redaction pdu.")
+                            })?;
+
+                    if let Some(redact_id) = &content.redacts {
+                        if !services().rooms.state_accessor.user_can_redact(
+                            redact_id,
+                            &pdu.sender,
+                            &pdu.room_id,
+                            false,
+                        )? {
+                            return Err(Error::BadRequest(
+                                ErrorKind::Forbidden,
+                                "User cannot redact this event.",
+                            ));
+                        }
+                    }
+                }
+                _ => {
+                    return Err(Error::BadRequest(
+                        ErrorKind::UnsupportedRoomVersion,
+                        "Unsupported room version",
+                    ));
+                }
             }
-        };
+        }
 
         // We append to state before appending the pdu, so we don't have a moment in time with the
         // pdu without it's state. This is okay because append_pdu can't fail.