fix(mosaic): serialize credential lifecycle mutations

2026-08-05 18:01:41 -05:00
parent 9512adcec2
commit b3d84662f9
10 changed files with 181 additions and 27 deletions
@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+"""Fail-closed reader for one legacy per-seat token file."""
+
+import os
+import stat
+import sys
+
+MAX_BYTES = 16 * 1024
+
+
+def refuse(message: str) -> None:
+    print(f"legacy credential refused: {message}", file=sys.stderr)
+    raise SystemExit(1)
+
+
+if len(sys.argv) != 2:
+    refuse("expected token path")
+path = sys.argv[1]
+parent = os.path.dirname(path)
+try:
+    parent_stat = os.stat(parent, follow_symlinks=False)
+except OSError:
+    refuse("credential directory unavailable")
+if not stat.S_ISDIR(parent_stat.st_mode) or stat.S_ISLNK(parent_stat.st_mode):
+    refuse("credential directory is not a real directory")
+if parent_stat.st_uid != os.getuid() or parent_stat.st_mode & 0o022:
+    refuse("credential directory owner or mode is unsafe")
+try:
+    fd = os.open(path, os.O_RDONLY | os.O_NOFOLLOW | os.O_CLOEXEC)
+except OSError:
+    refuse("credential file unavailable or symbolic")
+try:
+    file_stat = os.fstat(fd)
+    if not stat.S_ISREG(file_stat.st_mode):
+        refuse("credential is not a regular file")
+    if file_stat.st_uid != os.getuid() or file_stat.st_mode & 0o077:
+        refuse("credential owner or mode is unsafe")
+    content = os.read(fd, MAX_BYTES + 1)
+    if len(content) > MAX_BYTES:
+        refuse("credential exceeds size limit")
+finally:
+    os.close(fd)
+try:
+    token = content.decode("utf-8").strip()
+except UnicodeDecodeError:
+    refuse("credential is not UTF-8")
+if not token or any(ch.isspace() for ch in token):
+    refuse("credential token is invalid")
+sys.stdout.write(token + "\n")