Changeset 08d4fa6 for asadb

Timestamp:

Sep 15, 2012, 9:53:40 PM (13 years ago)

Author:

Alex Dehnert <adehnert@…>

Branches:

master, space-access, stable, stage

Children:

cf4b7f4

Parents:

3113644

git-author:

Alex Dehnert <adehnert@…> (09/15/12 21:53:40)

git-committer:

Alex Dehnert <adehnert@…> (09/15/12 21:53:40)

Message:

Wrappers for safely calling commands in a new PAG

The usual mechanism for starting a new PAG is pagsh(1). Unfortunately, because
it basically just execvp(3) /bin/sh passing the appropriate arguments, it isn't
immediately obvious how to safely pass arguments that may contain shell
metacharacters. By using the shell's exec and taking advantage of the fact that
later arguments to /bin/sh end up in $@ we can safely avoid shell
metacharacters. We wrap subprocess.check_{call,output} in
pag_check_{call,output}, which perform appropriate contortions to establish the
PAG before safely executing the passed commands without evaluating any
metacharacters.

File:

• asadb/mit/__init__.py (modified) (2 diffs)

asadb/mit/__init__.py

@@ +1 @@
+import os
 import subprocess
 import ldap
@@ -29 +30 @@
         except ValidationError:
             raise ValidationError('Provide a valid URL or AFS path')
+
+def pag_check_helper(fn, args, aklog=False, ccname=None, **kwargs):
+    if 'executable' in kwargs:
+        raise ValueError('"executable" not supported with pag_check_*')
+
+    env = None
+    if 'env' in kwargs:
+        env = kwargs['env']
+        del kwargs['env']
+    if ccname:
+        if env is not None:
+            env = dict(env)
+        else:
+            env = dict(os.environ)
+        env['KRB5CCNAME'] = ccname
+
+    pagsh_cmd = 'exec "$@"'
+    if aklog: pagsh_cmd = "aklog && " + pagsh_cmd
+    args = ['pagsh', '-c', pagsh_cmd, 'exec', ] + args
+
+    return fn(args, env=env, **kwargs)
+
+def pag_check_call(args, **kwargs):
+    return pag_check_helper(subprocess.check_call, args, **kwargs)
+def pag_check_output(args, **kwargs):
+    return pag_check_helper(subprocess.check_output, args, **kwargs)
 
 class ScriptsRemoteUserMiddleware(RemoteUserMiddleware):