Ability to run scripts as different user.

src/formconfig.py

@@ -8,8 +8,17 @@ import logging
 import stat
 import os
 import subprocess
+import pwd
+import grp
 
 
+def run_as(uid, gid, groups):
+    def set_acc():
+        os.setgroups(groups)
+        os.setgid(gid)
+        os.setuid(uid)
+    return set_acc
+
 class FormConfigError(Exception):
     """
     Default error for FormConfig errors
@@ -77,6 +86,7 @@ class FormConfig(object):
         callback should be written. The output of the script is hooked up to
         the output, depending on the output type.
         """
+        # FIXME: This doesn't really belong in FormCOnfig.
         form = self.get_form_def(form_name)
 
         # Validate params
@@ -90,26 +100,54 @@ class FormConfig(object):
         for key, value in form_values.items():
             env[key] = str(value)
 
+        # Get the user uid, gid and groups we should run as
+        pw = pwd.getpwnam(form.run_as)
+        gr = grp.getgrgid(pw.pw_gid)
+        groups = [g.gr_gid for g in grp.getgrall() if pw.pw_name in g.gr_mem]
+        uid = pw.pw_uid
+        gid = pw.pw_gid
+        msg = "Running script as user={0}, gid={1}, groups={2}"
+        self.log.info(msg.format(pw.pw_name, gr.gr_name, str(groups)))
+        if os.getuid() != 0:
+            self.log.error("Not running as root! Running as different user "
+                           "will probably fail!")
+
         # If the form output type is 'raw', we directly stream the output to
         # the browser. Otherwise we store it for later displaying.
         if form.output == 'raw':
-            proc = subprocess.Popen(form.script, shell=True,
-                                    stdout=stdout,
-                                    stderr=stderr,
-                                    env=env,
-                                    close_fds=True)
-            stdout, stderr = proc.communicate(input)
-            return proc.returncode
+            try:
+                proc = subprocess.Popen(form.script, shell=True,
+                                        stdout=stdout,
+                                        stderr=stderr,
+                                        env=env,
+                                        close_fds=True,
+                                        preexec_fn = run_as(uid, gid, groups))
+                stdout, stderr = proc.communicate(input)
+                return proc.returncode
+            except OSError as err:
+                self.log.exception(err)
+                stderr.write(str(err) + '. Please see the log file.')
+                return -1
         else:
-            proc = subprocess.Popen(form.script, shell=True,
-                                    stdin=subprocess.PIPE,
-                                    stdout=subprocess.PIPE,
-                                    stderr=subprocess.PIPE,
-                                    env=env,
-                                    close_fds=True)
-            stdout, stderr = proc.communicate()
-            return {
-                'stdout': stdout,
-                'stderr': stderr,
-                'exitcode': proc.returncode
-            }
+            try:
+                proc = subprocess.Popen(form.script, shell=True,
+                                        stdin=subprocess.PIPE,
+                                        stdout=subprocess.PIPE,
+                                        stderr=subprocess.PIPE,
+                                        env=env,
+                                        close_fds=True,
+                                        preexec_fn = run_as(uid, gid, groups))
+                stdout, stderr = proc.communicate()
+                return {
+                    'stdout': stdout,
+                    'stderr': stderr,
+                    'exitcode': proc.returncode
+                }
+            except OSError as err:
+                self.log.exception(err)
+                return {
+                    'stdout': '',
+                    'stderr': 'Internal error: {0}. Please see the log ' \
+                              'file.'.format(str(err)),
+                    'exitcode': -1
+                }

src/formdefinition.py

@@ -19,7 +19,7 @@ class FormDefinition(object):
     """
     def __init__(self, name, title, description, fields, script,
                  output='escaped', hidden=False, submit_title="Submit",
-                 allowed_users=None):
+                 allowed_users=None, run_as='nobody'):
         self.name = name
         self.title = title
         self.description = description
@@ -29,6 +29,7 @@ class FormDefinition(object):
         self.hidden = hidden
         self.submit_title = submit_title
         self.allowed_users = allowed_users
+        self.run_as = run_as
 
         self.validate_field_defs(self.fields)
 

src/scriptform.py

@@ -115,7 +115,8 @@ class ScriptForm(object):
                                output=form.get('output', 'escaped'),
                                hidden=form.get('hidden', False),
                                submit_title=form.get('submit_title', 'Submit'),
-                               allowed_users=form.get('allowed_users', None))
+                               allowed_users=form.get('allowed_users', None),
+                               run_as=form.get('run_as', 'nobody'))
             )
 
         form_config = FormConfig(