Validate vault's file parameters

A user can pass file names for password, public and private key files to
the vault plugin. The plugin attempts to read from these files. If any
file can't be, an internal error was raised. The patch wraps all reads
and turns any IOError and UnicodeError into a ValidationError.

https://fedorahosted.org/freeipa/ticket/5155

Reviewed-By: Martin Basti <mbasti@redhat.com>

ipalib/plugins/vault.py

@@ -19,6 +19,7 @@
 
 import base64
 import getpass
+import io
 import json
 import os
 import sys
@@ -210,6 +211,33 @@ EXAMPLES:
    ipa vault-remove-member <name> --users <usernames>
 """)
 
+
+def validated_read(argname, filename, mode='r', encoding=None):
+    """Read file and catch errors
+
+    IOError and UnicodeError (for text files) are turned into a
+    ValidationError
+    """
+    try:
+        with io.open(filename, mode=mode, encoding=encoding) as f:
+            data = f.read()
+    except IOError as exc:
+        raise errors.ValidationError(
+            name=argname,
+            error=_("Cannot read file '%(filename)s': %(exc)s") % {
+                'filename': filename, 'exc': exc[1]
+                }
+        )
+    except UnicodeError as exc:
+        raise errors.ValidationError(
+            name=argname,
+            error=_("Cannot decode file '%(filename)s': %(exc)s") % {
+                'filename': filename, 'exc': exc
+                }
+        )
+    return data
+
+
 register = Registry()
 
 
@@ -591,8 +619,10 @@ class vault_add(PKQuery, Local):
                 pass
 
             elif password_file:
-                with open(password_file, 'rb') as f:
+                password = validated_read('password-file',
-                    password = f.read().rstrip('\n').decode('utf-8')
+                                          password_file,
+                                          encoding='utf-8')
+                password = password.rstrip('\n')
 
             else:
                 password = self.obj.get_new_password()
@@ -611,8 +641,9 @@ class vault_add(PKQuery, Local):
                 pass
 
             elif public_key_file:
-                with open(public_key_file, 'rb') as f:
+                public_key = validated_read('public-key-file',
-                    public_key = f.read()
+                                            public_key_file,
+                                            mode='rb')
 
                 # store vault public key
                 options['ipavaultpublickey'] = public_key
@@ -904,8 +935,7 @@ class vault_archive(PKQuery, Local):
                 reason=_('Input data specified multiple times'))
 
         elif input_file:
-            with open(input_file, 'rb') as f:
+            data = validated_read('in', input_file, mode='rb')
-                data = f.read()
 
         elif not data:
             data = ''
@@ -937,8 +967,10 @@ class vault_archive(PKQuery, Local):
                 pass
 
             elif password_file:
-                with open(password_file) as f:
+                password = validated_read('password-file',
-                    password = f.read().rstrip('\n').decode('utf-8')
+                                          password_file,
+                                          encoding='utf-8')
+                password = password.rstrip('\n')
 
             else:
                 password = self.obj.get_existing_password()
@@ -1254,8 +1286,10 @@ class vault_retrieve(PKQuery, Local):
                 pass
 
             elif password_file:
-                with open(password_file) as f:
+                password = validated_read('password-file',
-                    password = f.read().rstrip('\n').decode('utf-8')
+                                          password_file,
+                                          encoding='utf-8')
+                password = password.rstrip('\n')
 
             else:
                 password = self.obj.get_existing_password()
@@ -1277,8 +1311,9 @@ class vault_retrieve(PKQuery, Local):
                 pass
 
             elif private_key_file:
-                with open(private_key_file, 'rb') as f:
+                private_key = validated_read('private-key-file',
-                    private_key = f.read()
+                                             private_key_file,
+                                             mode='rb')
 
             else:
                 raise errors.ValidationError(