Make sure permissions on cookie files are set sanely

Signed-off-by: Patrick Uiterwijk <puiterwijk@redhat.com>

Author: puiterwijk

fedora/client/__init__.py

@@ -28,6 +28,8 @@
 .. moduleauthor:: Luke Macken <lmacken@redhat.com>
 .. moduleauthor:: Toshio Kuratomi <tkuratom@redhat.com>
 '''
+import errno
+import os
 import warnings
 
 from munch import Munch
@@ -113,6 +115,16 @@ def __repr__(self):
             self.name, self.message, self.extras)
 
 
+class UnsafeFileError(Exception):
+    def __init__(self, filename, message):
+        super(UnsafeFileError, self).__init__(message)
+        self.message = message
+        self.filename = filename
+
+    def __str__(self):
+        return 'Unsafe file permissions! {}: {}'.format(self.filename,
+                                                        self.message)
+
 
 # Backwards compatibility
 class DictContainer(Munch):
@@ -123,6 +135,23 @@ def __init__(self, *args, **kwargs):
         Munch.__init__(self, *args, **kwargs)
 
 
+def check_file_permissions(filename, allow_notexists=False):
+    if os.path.islink(filename):
+        raise UnsafeFileError(filename, 'File is a symlink')
+    try:
+        stat = os.stat(filename)
+    except OSError as e:
+        if e.errno == errno.ENOENT and allow_notexists:
+            return
+        raise
+    if stat.st_uid != os.getuid():
+        raise UnsafeFileError(filename, 'File not owned by current user')
+    if stat.st_gid != os.getgid():
+        raise UnsafeFileError(filename, 'File not owner by primary group')
+    if stat.st_mode & 0o007:
+        raise UnsafeFileError(filename, 'File is world-readable')
+
+
 # We want people to be able to import fedora.client.*Client directly
 # pylint: disable-msg=W0611
 from fedora.client.proxyclient import ProxyClient

fedora/client/openidbaseclient.py

@@ -47,7 +47,11 @@
 from kitchen.text.converters import to_bytes
 
 from fedora import __version__
-from fedora.client import AuthError, LoginRequiredError, ServerError
+from fedora.client import (AuthError,
+                           LoginRequiredError,
+                           ServerError,
+                           UnsafeFileError,
+                           check_file_permissions)
 from fedora.client.openidproxyclient import (
     OpenIdProxyClient, absolute_url, openid_login)
 
@@ -182,7 +186,7 @@ def _initialize_session_cache(self):
         # for their password over and over.
         if not os.path.isdir(b_SESSION_DIR):
             try:
-                os.makedirs(b_SESSION_DIR, mode=0o755)
+                os.makedirs(b_SESSION_DIR, mode=0o750)
             except OSError as err:
                 log.warning('Unable to create {file}: {error}'.format(
                     file=b_SESSION_DIR, error=err))
@@ -301,6 +305,12 @@ def _load_cookies(self):
         if not self.cache_session:
             return
 
+        try:
+            check_file_permissions(b_SESSION_FILE, True)
+        except UnsafeFileError as e:
+            log.debug('Current sessions ignored: {}'.format(str(e)))
+            return
+
         try:
             with self.cache_lock:
                 with open(b_SESSION_FILE, 'rb') as f:
@@ -312,24 +322,33 @@ def _load_cookies(self):
         except IOError:
             # The file doesn't exist, so create it.
             log.debug("Creating %s", b_SESSION_FILE)
+            oldmask = os.umask(0o027)
             with open(b_SESSION_FILE, 'wb') as f:
                 f.write(json.dumps({}).encode('utf-8'))
+            os.umask(oldmask)
 
     def _save_cookies(self):
         if not self.cache_session:
             return
 
         with self.cache_lock:
             try:
+                check_file_permissions(b_SESSION_FILE, True)
                 with open(b_SESSION_FILE, 'rb') as f:
                     data = json.loads(f.read().decode('utf-8'))
+            except UnsafeFileError as e:
+                log.debug('Clearing sessions: {}'.format(str(e)))
+                os.unlink(b_SESSION_FILE)
+                data = {}
             except Exception:
                 log.warn("Failed to open cookie cache before saving.")
                 data = {}
 
+            oldmask = os.umask(0o027)
             data[self.session_key] = self._session.cookies.items()
             with open(b_SESSION_FILE, 'wb') as f:
                 f.write(json.dumps(data).encode('utf-8'))
+            os.umask(oldmask)
 
 
 __all__ = ('OpenIdBaseClient', 'requires_login')