security(upload): add permission to upload_file_streaming()

src/application/ports/file_ports.rs

@@ -60,6 +60,25 @@ pub trait FileUploadUseCase: Send + Sync + 'static {
         caller_id: Uuid,
     ) -> Result<FileDto, DomainError>;
 
+    /// `_with_perms` variant of `upload_file_streaming` — enforces
+    /// `Create` on the target folder before registering the row.
+    ///
+    /// AuthZ audit #17 (2026-07-12): the chunked-upload `complete`
+    /// path called plain `upload_file_streaming` at finalize; a grant
+    /// revoked between session open and finalize stayed effective
+    /// until the caller landed the final chunk (up to 24h JWT TTL,
+    /// forever with app-passwords). Handlers now call this variant
+    /// so the engine re-checks at finalize regardless of how long
+    /// the session was open.
+    async fn upload_file_streaming_with_perms(
+        &self,
+        name: String,
+        folder_id: Option<String>,
+        content_type: String,
+        blob: StoredBlob,
+        caller_id: Uuid,
+    ) -> Result<FileDto, DomainError>;
+
     /// Replace the content of the file at `path` with an already-ingested
     /// blob, or create the file when it doesn't exist (WebDAV/WOPI PUT).
     ///

src/application/services/file_upload_service.rs

@@ -457,6 +457,44 @@ impl FileUploadUseCase for FileUploadService {
         Ok(dto)
     }
 
+    /// AuthZ audit #17 — `Create` on target folder is re-verified here
+    /// so mid-session grant revocations take effect at finalize. When
+    /// `folder_id` is `None` the write lands at drive-root; the drive
+    /// resolution for that case isn't plumbed through the chunked-
+    /// upload session (`UploadSession.folder_id` alone), so we fall
+    /// back to the pre-audit behaviour there. That drive-root path is
+    /// tracked separately as part of the D0 folder-id-walking work;
+    /// closing it here would require session-scoped drive_id.
+    async fn upload_file_streaming_with_perms(
+        &self,
+        name: String,
+        folder_id: Option<String>,
+        content_type: String,
+        blob: StoredBlob,
+        caller_id: Uuid,
+    ) -> Result<FileDto, DomainError> {
+        if let Some(fid) = folder_id.as_deref() {
+            let Some(authz) = &self.authorization else {
+                return Err(DomainError::internal_error(
+                    "FileUpload",
+                    "upload_file_streaming_with_perms called without authorization engine wired",
+                ));
+            };
+            let folder_uuid = Uuid::parse_str(fid)
+                .map_err(|_| DomainError::not_found("Folder", fid.to_string()))?;
+            authz
+                .require(
+                    Subject::User(caller_id),
+                    Permission::Create,
+                    Resource::Folder(folder_uuid),
+                )
+                .await?;
+        }
+
+        self.upload_file_streaming(name, folder_id, content_type, blob, caller_id)
+            .await
+    }
+
     /// Swap the content of the file at `path` to an already-ingested blob,
     /// creating the file when it doesn't exist (WebDAV/NextCloud/WOPI PUT).
     ///

src/common/stubs.rs

@@ -511,6 +511,17 @@ impl FileUploadUseCase for StubFileUploadUseCase {
     ) -> Result<FileDto, DomainError> {
         Ok(FileDto::default())
     }
+
+    async fn upload_file_streaming_with_perms(
+        &self,
+        _name: String,
+        _folder_id: Option<String>,
+        _content_type: String,
+        _blob: StoredBlob,
+        _caller_id: Uuid,
+    ) -> Result<FileDto, DomainError> {
+        Ok(FileDto::default())
+    }
 }
 
 // ---------------------------------------------------------------------------

src/interfaces/api/handlers/chunked_upload_handler.rs

@@ -188,9 +188,14 @@ impl ChunkedUploadHandler {
 
         // ── Permission pre-check: caller must have Create on the target
         // folder BEFORE we allocate a session and accept chunks. The
-        // upload service re-checks at finalize time, but failing here
-        // avoids wasting client+server resources on chunks that will be
-        // rejected. None = caller's root namespace, no check needed.
+        // upload service re-checks at finalize via
+        // `upload_file_streaming_with_perms` (AuthZ audit #17 fix,
+        // 2026-07-16) so a grant revoked mid-session is caught. This
+        // pre-check is the fail-fast: it avoids wasting client+server
+        // resources on chunks that will be rejected anyway. `None`
+        // means the write lands at drive-root — that path is currently
+        // unchecked (session doesn't carry `drive_id`; tracked with the
+        // folder-id-walking follow-up).
         if let Some(ref fid) = request.folder_id
             && let Err(err) = state
                 .applications
@@ -441,9 +446,17 @@ impl ChunkedUploadHandler {
         }
 
         // Register the file row against the ingested blob.
+        //
+        // AuthZ audit #17 (2026-07-12): swapped `upload_file_streaming` →
+        // `upload_file_streaming_with_perms` so `Create` on the target
+        // folder is re-verified at finalize. Session creation already
+        // pre-checked (line ~198), but that was potentially hours or
+        // days ago; app-passwords keep sessions valid indefinitely.
+        // Without the finalize re-check, a grant revoked mid-session
+        // stayed effective until the last chunk landed.
         let size = ingested.size;
         match upload_service
-            .upload_file_streaming(
+            .upload_file_streaming_with_perms(
                 parts.filename.clone(),
                 parts.folder_id.clone(),
                 ingested.content_type.clone(),