-
Notifications
You must be signed in to change notification settings - Fork 4
/
process.py
487 lines (396 loc) · 15.3 KB
/
process.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
import errno
import fcntl
import logging
import os
import pty
import select
import subprocess
import tty
from ..context import context
from ..log import getLogger
from ..timeout import Timeout
from ..util.misc import which
from .tube import tube
log = getLogger(__name__)
PIPE = subprocess.PIPE
STDOUT = subprocess.STDOUT
PTY = object()
class process(tube):
r"""
Spawns a new process, and wraps it with a tube for communication.
Arguments:
argv(list):
List of arguments to pass to the spawned process.
shell(bool):
Set to `True` to interpret `argv` as a string
to pass to the shell for interpretation instead of as argv.
executable(str):
Path to the binary to execute. If ``None``, uses ``argv[0]``.
Cannot be used with ``shell``.
cwd(str):
Working directory. Uses the current working directory by default.
env(dict):
Environment variables. By default, inherits from Python's environment.
timeout(int):
Timeout to use on ``tube`` ``recv`` operations.
stdin(int):
File object or file descriptor number to use for ``stdin``.
By default, a pipe is used.
stdout(int):
File object or file descriptor number to use for ``stdout``.
By default, a pty is used.
May also be ``subprocess.PIPE`` to use a normal pipe.
stderr(int):
File object or file descriptor number to use for ``stderr``.
By default, ``stdout`` is used.
May also be ``subprocess.PIPE`` to use a separate pipe,
although the ``tube`` wrapper will not be able to read this data.
preexec_fn(callable):
Callable to invoke immediately before calling ``execve``.
Examples:
>>> p = process(which('python2'))
>>> p.sendline("print 'Hello world'")
>>> p.sendline("print 'Wow, such data'");
>>> '' == p.recv(timeout=0.01)
True
>>> p.shutdown('send')
>>> p.proc.stdin.closed
True
>>> p.connected('send')
False
>>> p.recvline()
'Hello world\n'
>>> p.recvuntil(',')
'Wow,'
>>> p.recvregex('.*data')
' such data'
>>> p.recv()
'\n'
>>> p.recv() # doctest: +ELLIPSIS
Traceback (most recent call last):
...
EOFError
>>> p = process('cat')
>>> d = open('/dev/urandom').read(4096)
>>> p.recv(timeout=0.1)
''
>>> p.write(d)
>>> p.recvrepeat(0.1) == d
True
>>> p.recv(timeout=0.1)
''
>>> p.shutdown('send')
>>> p.wait_for_close()
>>> p.poll()
0
>>> p = process('cat /dev/zero | head -c8', shell=True, stderr=open('/dev/null', 'w+'))
>>> p.recv()
'\x00\x00\x00\x00\x00\x00\x00\x00'
>>> p = process(['python','-c','import os; print os.read(2,1024)'],
... preexec_fn = lambda: os.dup2(0,2))
>>> p.sendline('hello')
>>> p.recvline()
'hello\n'
>>> p = process(['python','-c','open("/dev/tty","wb").write("stack smashing detected")'])
>>> p.recv()
'stack smashing detected'
"""
#: `subprocess.Popen` object
proc = None
#: Full path to the executable
executable = None
#: Full path to the executable
program = None
#: Arguments passed on argv
argv = None
#: Environment passed on envp
env = None
#: Directory the process was created in
cwd = None
#: Have we seen the process stop?
_stop_noticed = False
def __init__(self, argv,
shell = False,
executable = None,
cwd = None,
env = None,
timeout = Timeout.default,
stdin = PIPE,
stdout = PTY,
stderr = STDOUT,
close_fds = True,
preexec_fn = lambda: None):
super(process, self).__init__(timeout)
if not shell:
executable, argv, env = self._validate(cwd, executable, argv, env)
stdin, stdout, stderr, master = self._handles(stdin, stdout, stderr)
self.executable = self.program = executable
self.argv = argv
self.env = env
self.cwd = cwd or os.path.curdir
self.preexec_user = preexec_fn
# message = "Starting program %r" % self.program
#
# if log.isEnabledFor(logging.INFO):
# if self.argv != [self.executable]: message += ' argv=%r ' % self.argv
# if self.env != os.environ: message += ' env=%r ' % self.env
#
# with log.progress(message) as p:
self.proc = subprocess.Popen(args = argv,
shell = shell,
executable = executable,
cwd = cwd,
env = env,
stdin = stdin,
stdout = stdout,
stderr = stderr,
close_fds = close_fds,
preexec_fn = self.preexec_fn)
if master:
self.proc.stdout = os.fdopen(master)
os.close(stdout)
# Set in non-blocking mode so that a call to call recv(1000) will
# return as soon as a the first byte is available
fd = self.proc.stdout.fileno()
fl = fcntl.fcntl(fd, fcntl.F_GETFL)
fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
def preexec_fn(self):
self.__pty_make_controlling_tty(1)
self.preexec_user()
@staticmethod
def _validate(cwd, executable, argv, env):
"""
Perform extended validation on the executable path, argv, and envp.
Mostly to make Python happy, but also to prevent common pitfalls.
"""
cwd = cwd or os.path.curdir
#
# Validate argv
#
# - Must be a list/tuple of strings
# - Each string must not contain '\x00'
#
if isinstance(argv, (str, unicode)):
argv = [argv]
if not all(isinstance(arg, (str, unicode)) for arg in argv):
log.error("argv must be strings: %r" % argv)
# Create a duplicate so we can modify it
argv = list(argv or [])
for i, arg in enumerate(argv):
if '\x00' in arg[:-1]:
log.error('Inappropriate nulls in argv[%i]: %r' % (i, arg))
argv[i] = arg.rstrip('\x00')
#
# Validate executable
#
# - Must be an absolute or relative path to the target executable
# - If not, attempt to resolve the name in $PATH
#
if not executable:
if not argv:
log.error("Must specify argv or executable")
executable = argv[0]
# Do not change absolute paths to binaries
if executable.startswith(os.path.sep):
pass
# If there's no path component, it's in $PATH or relative to the
# target directory.
#
# For example, 'sh'
elif os.path.sep not in executable and which(executable):
executable = which(executable)
# Either there is a path component, or the binary is not in $PATH
# For example, 'foo/bar' or 'bar' with cwd=='foo'
elif os.path.sep not in executable:
executable = os.path.join(cwd, executable)
if not os.path.exists(executable):
log.error("%r does not exist" % executable)
if not os.path.isfile(executable):
log.error("%r is not a file" % executable)
if not os.access(executable, os.X_OK):
log.error("%r is not marked as executable (+x)" % executable)
#
# Validate environment
#
# - Must be a dictionary of {string:string}
# - No strings may contain '\x00'
#
# Create a duplicate so we can modify it safely
env = dict(env or os.environ)
for k,v in env.items():
if not isinstance(k, (str, unicode)):
log.error('Environment keys must be strings: %r' % k)
if not isinstance(k, (str, unicode)):
log.error('Environment values must be strings: %r=%r' % (k,v))
if '\x00' in k[:-1]:
log.error('Inappropriate nulls in env key: %r' % (k))
if '\x00' in v[:-1]:
log.error('Inappropriate nulls in env value: %r=%r' % (k, v))
env[k.rstrip('\x00')] = v.rstrip('\x00')
return executable, argv, env
@staticmethod
def _handles(stdin, stdout, stderr):
master = None
if stdout is PTY:
# Normally we could just use subprocess.PIPE and be happy.
# Unfortunately, this results in undesired behavior when
# printf() and similar functions buffer data instead of
# sending it directly.
#
# By opening a PTY for STDOUT, the libc routines will not
# buffer any data on STDOUT.
master, slave = pty.openpty()
# By making STDOUT a PTY, the OS will attempt to interpret
# terminal control codes. We don't want this, we want all
# input passed exactly and perfectly to the process.
tty.setraw(master)
tty.setraw(slave)
# Pick one side of the pty to pass to the child
stdout = slave
return stdin, stdout, stderr, master
def kill(self):
"""kill()
Kills the process.
"""
self.close()
def poll(self):
"""poll() -> int
Poll the exit code of the process. Will return None, if the
process has not yet finished and the exit code otherwise.
"""
self.proc.poll()
if self.proc.returncode != None and not self._stop_noticed:
self._stop_noticed = True
#log.info("Program %r stopped with exit code %d" % (self.program, self.proc.returncode))
return self.proc.returncode
def communicate(self, stdin = None):
"""communicate(stdin = None) -> str
Calls :meth:`subprocess.Popen.communicate` method on the process.
"""
return self.proc.communicate(stdin)
# Implementation of the methods required for tube
def recv_raw(self, numb):
# This is a slight hack. We try to notice if the process is
# dead, so we can write a message.
self.poll()
if not self.connected_raw('recv'):
raise EOFError
if not self.can_recv_raw(self.timeout):
return ''
# This will only be reached if we either have data,
# or we have reached an EOF. In either case, it
# should be safe to read without expecting it to block.
data = ''
try:
data = self.proc.stdout.read(numb)
except IOError as (err, strerror):
pass
if not data:
self.shutdown("recv")
raise EOFError
return data
def send_raw(self, data):
# This is a slight hack. We try to notice if the process is
# dead, so we can write a message.
self.poll()
if not self.connected_raw('send'):
raise EOFError
try:
self.proc.stdin.write(data)
self.proc.stdin.flush()
except IOError:
raise EOFError
def settimeout_raw(self, timeout):
pass
def can_recv_raw(self, timeout):
if not self.connected_raw('recv'):
return False
try:
if timeout == None:
return select.select([self.proc.stdout], [], []) == ([self.proc.stdout], [], [])
return select.select([self.proc.stdout], [], [], timeout) == ([self.proc.stdout], [], [])
except ValueError:
# Not sure why this isn't caught when testing self.proc.stdout.closed,
# but it's not.
#
# File "/home/user/pwntools/pwnlib/tubes/process.py", line 112, in can_recv_raw
# return select.select([self.proc.stdout], [], [], timeout) == ([self.proc.stdout], [], [])
# ValueError: I/O operation on closed file
raise EOFError
def connected_raw(self, direction):
if direction == 'any':
return self.poll() == None
elif direction == 'send':
return not self.proc.stdin.closed
elif direction == 'recv':
return not self.proc.stdout.closed
def close(self):
if self.proc is None:
return
# First check if we are already dead
self.poll()
#close file descriptors
if self.proc.stdin is not None:
self.proc.stdin.close()
if self.proc.stderr is not None:
self.proc.stderr.close()
if self.proc.stdout is not None:
self.proc.stdout.close()
if not self._stop_noticed:
try:
self.proc.kill()
self.proc.wait() #avoid leaving zombies around
self._stop_noticed = True
log.info('Stopped program %r' % self.program)
except OSError:
pass
def fileno(self):
if not self.connected():
log.error("A stopped program does not have a file number")
return self.proc.stdout.fileno()
def shutdown_raw(self, direction):
if direction == "send":
self.proc.stdin.close()
if direction == "recv":
self.proc.stdout.close()
if False not in [self.proc.stdin.closed, self.proc.stdout.closed]:
self.close()
def __pty_make_controlling_tty(self, tty_fd):
'''This makes the pseudo-terminal the controlling tty. This should be
more portable than the pty.fork() function. Specifically, this should
work on Solaris. '''
child_name = os.ttyname(tty_fd)
# Disconnect from controlling tty. Harmless if not already connected.
try:
fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
if fd >= 0:
os.close(fd)
# which exception, shouldnt' we catch explicitly .. ?
except OSError:
# Already disconnected. This happens if running inside cron.
pass
os.setsid()
# Verify we are disconnected from controlling tty
# by attempting to open it again.
try:
fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
if fd >= 0:
os.close(fd)
raise Exception('Failed to disconnect from ' +
'controlling tty. It is still possible to open /dev/tty.')
# which exception, shouldnt' we catch explicitly .. ?
except OSError:
# Good! We are disconnected from a controlling tty.
pass
# Verify we can open child pty.
fd = os.open(child_name, os.O_RDWR)
if fd < 0:
raise Exception("Could not open child pty, " + child_name)
else:
os.close(fd)
# Verify we now have a controlling tty.
fd = os.open("/dev/tty", os.O_WRONLY)
if fd < 0:
raise Exception("Could not open controlling tty, /dev/tty")
else:
os.close(fd)