sanitize S3 log key filename to prevent 403 for s3:// batch file IDs

litellm/integrations/s3.py

@@ -185,12 +185,36 @@ def get_s3_object_key(
     start_time: datetime,
     s3_file_name: str,
 ) -> str:
+    # `s3_file_name` sometimes comes from an upstream "id" that can be an S3 URI
+    # (e.g. `s3://bucket/some/key.jsonl`). If we include `/` directly in the
+    # object key filename component, it creates extra path segments and can
+    # break S3 bucket/prefix IAM policies.
+    raw_file_name = "" if s3_file_name is None else str(s3_file_name)
+    import hashlib
+    import re
+
+    # Replace any characters outside the safe filename set.
+    # This also converts `/` and `:` into `_`, preventing accidental directory
+    # traversal / extra IAM prefix segments.
+    safe_file_name = re.sub(r"[^A-Za-z0-9._-]+", "_", raw_file_name)
+    safe_file_name = safe_file_name.strip("_")
+
+    if not safe_file_name:
+        # Fall back to a deterministic value to avoid empty keys.
+        safe_file_name = "unknown"
+
+    # Keep keys reasonably small even if `id` is a long URI.
+    max_len = 180
+    if len(safe_file_name) > max_len:
+        suffix_hash = hashlib.sha256(raw_file_name.encode("utf-8")).hexdigest()[:12]
+        safe_file_name = f"{safe_file_name[: max_len - 13]}_{suffix_hash}"
+
     s3_object_key = (
         (s3_path.rstrip("/") + "/" if s3_path else "")
         + prefix
         + start_time.strftime("%Y-%m-%d")
         + "/"
-        + s3_file_name
+        + safe_file_name
     )  # we need the s3 key to include the time, so we log cache hits too
     s3_object_key += ".json"
     return s3_object_key

tests/test_litellm/integrations/test_s3_object_key.py

@@ -0,0 +1,29 @@
+from datetime import datetime, timezone
+
+from litellm.integrations.s3 import get_s3_object_key
+
+
+def test_get_s3_object_key_sanitizes_embedded_s3_uri_in_filename():
+    start_time = datetime(2026, 3, 9, 17, 40, 11, 901585, tzinfo=timezone.utc)
+    s3_path = "LiteLLMAPPLogs"
+    prefix = ""
+    s3_file_name = (
+        "time-17-40-11-901585_s3://bucket-int/litellm-bedrock-files-us.anthropic."
+        "claude-sonnet-4-5-20250929-v1-0-29ea93-452e-8a2f.jsonl.json"
+    )
+
+    s3_object_key = get_s3_object_key(
+        s3_path=s3_path,
+        prefix=prefix,
+        start_time=start_time,
+        s3_file_name=s3_file_name,
+    )
+
+    assert s3_object_key.startswith("LiteLLMAPPLogs/2026-03-09/")
+    assert s3_object_key.endswith(".json")
+
+    # The only path separators allowed are the ones we generate for prefix/date.
+    file_component = s3_object_key[len("LiteLLMAPPLogs/2026-03-09/") :]
+    assert "/" not in file_component
+    assert "s3://" not in s3_object_key
+