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keep_cred.py
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Tue, Jul 1, 14:31

keep_cred.py
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#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
keep_cred : receives user credentials during pam auth.
It keeps it until KEEP_CRED_TIMEOUT.
Other applications (extensions) can ask it to do operations that need credentials.
Extensions have to configure themselves with an /usr/local/lib/keep_cred/app.py
They have to implement :
+ FLAG_FILE : the file that flags it's epfl_roaming that sent USR1 signal to keep_cred
+ run(username, password) method that does the job
"""
import os
import sys
import time
import signal
import importlib
KEEP_CRED_TIMEOUT = 20 # sec
EXT_FOLDER = "/usr/local/lib/keep_cred"
EXT_FOLDER = os.path.normpath(os.path.join(__file__, "../../lib/keep_cred")) ## TODO DEBUG
VAR_RUN = "/var/run/keep_cred"
def fork_and_wait():
def signal_USR1_handler(signum, frame):
an_ext_was_run = False
for ext in extensions:
if os.path.exists(extensions[ext].FLAG_FILE):
an_ext_was_run = True
print "Running extension %s." % ext
extensions[ext].run(USERNAME, PASSWORD)
try:
os.unlink(extensions[ext].FLAG_FILE)
except:
pass
print "done."
if not an_ext_was_run:
print "got USR1 signal, but no extension were run."
if os.fork() != 0:
return
extensions = {}
# receive SIGUSR1 to trigger operations
signal.signal(signal.SIGUSR1, signal_USR1_handler)
sys.path.insert(0, EXT_FOLDER)
for f in os.listdir(EXT_FOLDER):
if f == "__init__.py" or not f.endswith(".py"):
continue
try:
ext_name = f[:-3]
mod = importlib.import_module(ext_name)
if ("FLAG_FILE" in dir(mod) and "run" in dir(mod) and
type(mod.FLAG_FILE) == str and callable(mod.run)):
extensions[ext_name] = mod
else:
print "Error, %s doesn't implement required variables and functions; Skipping." % ext_name
except Exception, e:
print "Error, could not import %s; Skipping." % ext_name
print e
for i in range(KEEP_CRED_TIMEOUT):
time.sleep(1)
print "Finished to wait for %i seconds; exiting." % KEEP_CRED_TIMEOUT
if __name__ == "__main__":
USERNAME = os.environ["PAM_USER"]
SERVICE = os.environ["PAM_SERVICE"]
TYPE = os.environ["PAM_TYPE"]
print "USERNAME %s" % USERNAME
print "SERVICE %s" % SERVICE
print "TYPE %s" % TYPE
if TYPE != "auth":
sys.exit(0)
PASSWORD = sys.stdin.readline().rstrip(chr(0))
try:
os.makedirs(VAR_RUN)
except OSError:
pass
fork_and_wait()
sys.exit(0)

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