1 """Functionality common to all account classes.
3 Each subclass of Account must provide five methods: create() and
4 destroy(), which are static; configure(), start(), and stop(), which
5 are not. configure(), which takes a record as its only argument, does
6 things like set up ssh keys. In addition, an Account subclass must
7 provide static member variables SHELL, which contains the unique shell
8 that it uses; and TYPE, a string that is used by the account creation
9 code. For no particular reason, TYPE is divided hierarchically by
10 periods; at the moment the only convention is that all sliver accounts
11 have type that begins with sliver.
13 There are any number of race conditions that may result from the fact
14 that account names are not unique over time. Moreover, it's a bad
15 idea to perform lengthy operations while holding the database lock.
16 In order to deal with both of these problems, we use a worker thread
17 for each account name that ever exists. On 32-bit systems with large
18 numbers of accounts, this may cause the NM process to run out of
19 *virtual* memory! This problem may be remedied by decreasing the
32 # When this variable is true, start after any ensure_created
35 # shell path -> account class association
37 # account type -> account class association
40 def register_class(acct_class):
41 """Call once for each account class. This method adds the class to the dictionaries used to look up account classes by shell and type."""
42 shell_acct_class[acct_class.SHELL] = acct_class
43 type_acct_class[acct_class.TYPE] = acct_class
46 # private account name -> worker object association and associated lock
47 name_worker_lock = threading.Lock()
51 return [pw_ent for pw_ent in pwd.getpwall() if pw_ent[6] in shell_acct_class]
54 """Return the names of all accounts on the system with recognized shells."""
55 return [pw_ent[0] for pw_ent in allpwents()]
58 """Return the worker object for a particular username. If no such object exists, create it first."""
59 name_worker_lock.acquire()
61 if name not in name_worker: name_worker[name] = Worker(name)
62 return name_worker[name]
63 finally: name_worker_lock.release()
67 def __init__(self, rec):
68 self.name = rec['name']
73 def create(name, vref = None): abstract
75 def destroy(name): abstract
77 def configure(self, rec):
78 """Write <rec['keys']> to my authorized_keys file."""
79 new_keys = rec['keys']
80 if new_keys != self.keys:
82 dot_ssh = '/home/%s/.ssh' % self.name
83 def do_installation():
84 if not os.access(dot_ssh, os.F_OK): os.mkdir(dot_ssh)
85 os.chmod(dot_ssh, 0700)
86 tools.write_file(dot_ssh + '/authorized_keys', lambda f: f.write(new_keys))
87 logger.log('%s: installing ssh keys' % self.name)
88 tools.fork_as(self.name, do_installation)
90 def start(self, delay=0): pass
95 # these semaphores are acquired before creating/destroying an account
96 _create_sem = threading.Semaphore(1)
97 _destroy_sem = threading.Semaphore(1)
99 def __init__(self, name):
100 self.name = name # username
101 self._acct = None # the account object currently associated with this worker
103 # outsiders request operations by putting (fn, args...) tuples on _q
104 # the worker thread (created below) will perform these operations in order
105 self._q = Queue.Queue()
106 tools.as_daemon_thread(self._run)
108 def ensure_created(self, rec):
109 """Cause the account specified by <rec> to exist if it doesn't already."""
110 self._q.put((self._ensure_created, rec.copy()))
112 def _ensure_created(self, rec):
113 curr_class = self._get_class()
114 next_class = type_acct_class[rec['type']]
115 if next_class != curr_class:
116 self._destroy(curr_class)
117 self._create_sem.acquire()
118 try: next_class.create(self.name, rec['vref'])
119 finally: self._create_sem.release()
120 if not isinstance(self._acct, next_class): self._acct = next_class(rec)
121 else: self._acct.configure(rec)
122 if next_class != curr_class or startingup:
125 def ensure_destroyed(self): self._q.put((self._ensure_destroyed,))
126 def _ensure_destroyed(self): self._destroy(self._get_class())
128 def start(self, delay=0): self._q.put((self._start, delay))
129 def _start(self, d): self._acct.start(delay=d)
131 def stop(self): self._q.put((self._stop,))
132 def _stop(self): self._acct.stop()
134 def _destroy(self, curr_class):
137 self._destroy_sem.acquire()
138 try: curr_class.destroy(self.name)
139 finally: self._destroy_sem.release()
141 def _get_class(self):
142 try: shell = pwd.getpwnam(self.name)[6]
143 except KeyError: return None
144 return shell_acct_class[shell]
147 """Repeatedly pull commands off the queue and execute. If memory usage becomes an issue, it might be wise to terminate after a while."""
152 except: logger.log_exc()