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
35 csd_lock = threading.Lock()
38 # shell path -> account class association
40 # account type -> account class association
43 def register_class(acct_class):
44 """Call once for each account class. This method adds the class to the dictionaries used to look up account classes by shell and type."""
45 shell_acct_class[acct_class.SHELL] = acct_class
46 type_acct_class[acct_class.TYPE] = acct_class
49 # private account name -> worker object association and associated lock
50 name_worker_lock = threading.Lock()
54 return [pw_ent for pw_ent in pwd.getpwall() if pw_ent[6] in shell_acct_class]
57 """Return the names of all accounts on the system with recognized shells."""
58 return [pw_ent[0] for pw_ent in allpwents()]
61 """Return the worker object for a particular username. If no such object exists, create it first."""
62 name_worker_lock.acquire()
64 if name not in name_worker: name_worker[name] = Worker(name)
65 return name_worker[name]
66 finally: name_worker_lock.release()
70 def __init__(self, rec):
71 logger.verbose('Initing account %s'%rec['name'])
72 self.name = rec['name']
74 self.initscriptchanged = False
78 def create(name, vref = None): abstract
80 def destroy(name): abstract
82 def configure(self, rec):
83 """Write <rec['keys']> to my authorized_keys file."""
84 logger.verbose('in accounts:configure for %s'%self.name)
85 new_keys = rec['keys']
86 if new_keys != self.keys:
88 dot_ssh = '/home/%s/.ssh' % self.name
89 def do_installation():
90 if not os.access(dot_ssh, os.F_OK): os.mkdir(dot_ssh)
91 os.chmod(dot_ssh, 0700)
92 tools.write_file(dot_ssh + '/authorized_keys', lambda f: f.write(new_keys))
93 logger.verbose('%s: installing ssh keys' % self.name)
94 tools.fork_as(self.name, do_installation)
96 def start(self, delay=0): pass
101 # these semaphores are acquired before creating/destroying an account
102 _create_sem = threading.Semaphore(1)
103 _destroy_sem = threading.Semaphore(1)
105 def __init__(self, name):
106 self.name = name # username
107 self._acct = None # the account object currently associated with this worker
109 # outsiders request operations by putting (fn, args...) tuples on _q
110 # the worker thread (created below) will perform these operations in order
111 self._q = Queue.Queue()
112 tools.as_daemon_thread(self._run)
114 def ensure_created(self, rec):
115 """Cause the account specified by <rec> to exist if it doesn't already."""
116 if rec.has_key('name'):
117 logger.verbose('Worker.ensure_created with name=%s'%rec['name'])
118 self._q.put((self._ensure_created, rec.copy(), Startingup))
119 logger.verbose('Worker queue has %d item(s)'%self._q.qsize())
121 def _ensure_created(self, rec, startingup):
122 curr_class = self._get_class()
123 next_class = type_acct_class[rec['type']]
124 if next_class != curr_class:
125 self._destroy(curr_class)
126 self._create_sem.acquire()
127 try: next_class.create(self.name, rec['vref'])
128 finally: self._create_sem.release()
129 if not isinstance(self._acct, next_class): self._acct = next_class(rec)
130 else: self._acct.configure(rec)
134 delay = cumstartdelay
137 self._acct.start(delay=delay)
138 elif next_class != curr_class or self._acct.initscriptchanged:
141 def ensure_destroyed(self): self._q.put((self._ensure_destroyed,))
142 def _ensure_destroyed(self): self._destroy(self._get_class())
144 def start(self, delay=0): self._q.put((self._start, delay))
145 def _start(self, d): self._acct.start(delay=d)
147 def stop(self): self._q.put((self._stop,))
148 def _stop(self): self._acct.stop()
150 def _destroy(self, curr_class):
153 self._destroy_sem.acquire()
154 try: curr_class.destroy(self.name)
155 finally: self._destroy_sem.release()
157 def _get_class(self):
158 try: shell = pwd.getpwnam(self.name)[6]
159 except KeyError: return None
160 return shell_acct_class[shell]
163 """Repeatedly pull commands off the queue and execute. If memory usage becomes an issue, it might be wise to terminate after a while."""
166 logger.verbose('Worker:_run : getting - size is %d'%self._q.qsize())
170 logger.log_exc(self.name)