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
34 # Cumulative delay for starts when startingup is true
37 # shell path -> account class association
39 # account type -> account class association
42 def register_class(acct_class):
43 """Call once for each account class. This method adds the class to the dictionaries used to look up account classes by shell and type."""
44 shell_acct_class[acct_class.SHELL] = acct_class
45 type_acct_class[acct_class.TYPE] = acct_class
48 # private account name -> worker object association and associated lock
49 name_worker_lock = threading.Lock()
53 return [pw_ent for pw_ent in pwd.getpwall() if pw_ent[6] in shell_acct_class]
56 """Return the names of all accounts on the system with recognized shells."""
57 return [pw_ent[0] for pw_ent in allpwents()]
60 """Return the worker object for a particular username. If no such object exists, create it first."""
61 name_worker_lock.acquire()
63 if name not in name_worker: name_worker[name] = Worker(name)
64 return name_worker[name]
65 finally: name_worker_lock.release()
69 def __init__(self, rec):
70 self.name = rec['name']
72 self.initscriptchanged = False
76 def create(name, vref = None): abstract
78 def destroy(name): abstract
80 def configure(self, rec):
81 """Write <rec['keys']> to my authorized_keys file."""
82 new_keys = rec['keys']
83 if new_keys != self.keys:
85 dot_ssh = '/home/%s/.ssh' % self.name
86 def do_installation():
87 if not os.access(dot_ssh, os.F_OK): os.mkdir(dot_ssh)
88 os.chmod(dot_ssh, 0700)
89 tools.write_file(dot_ssh + '/authorized_keys', lambda f: f.write(new_keys))
90 logger.log('%s: installing ssh keys' % self.name)
91 tools.fork_as(self.name, do_installation)
93 def start(self, delay=0): pass
98 # these semaphores are acquired before creating/destroying an account
99 _create_sem = threading.Semaphore(1)
100 _destroy_sem = threading.Semaphore(1)
102 def __init__(self, name):
103 self.name = name # username
104 self._acct = None # the account object currently associated with this worker
106 # outsiders request operations by putting (fn, args...) tuples on _q
107 # the worker thread (created below) will perform these operations in order
108 self._q = Queue.Queue()
109 tools.as_daemon_thread(self._run)
111 def ensure_created(self, rec):
112 """Cause the account specified by <rec> to exist if it doesn't already."""
113 self._q.put((self._ensure_created, rec.copy()))
115 def _ensure_created(self, rec):
116 curr_class = self._get_class()
117 next_class = type_acct_class[rec['type']]
118 if next_class != curr_class:
119 self._destroy(curr_class)
120 self._create_sem.acquire()
121 try: next_class.create(self.name, rec['vref'])
122 finally: self._create_sem.release()
123 if not isinstance(self._acct, next_class): self._acct = next_class(rec)
124 else: self._acct.configure(rec)
127 self._acct.start(delay=cumstartdelay)
129 elif next_class != curr_class or self._acct.initscriptchanged:
132 def ensure_destroyed(self): self._q.put((self._ensure_destroyed,))
133 def _ensure_destroyed(self): self._destroy(self._get_class())
135 def start(self, delay=0): self._q.put((self._start, delay))
136 def _start(self, d): self._acct.start(delay=d)
138 def stop(self): self._q.put((self._stop,))
139 def _stop(self): self._acct.stop()
141 def _destroy(self, curr_class):
144 self._destroy_sem.acquire()
145 try: curr_class.destroy(self.name)
146 finally: self._destroy_sem.release()
148 def _get_class(self):
149 try: shell = pwd.getpwnam(self.name)[6]
150 except KeyError: return None
151 return shell_acct_class[shell]
154 """Repeatedly pull commands off the queue and execute. If memory usage becomes an issue, it might be wise to terminate after a while."""
159 except: logger.log_exc()