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#!/usr/bin/python3 -u
import code
import io
import pickle
import sys
import seccomp
f = seccomp.SyscallFilter(defaction=seccomp.KILL)
# Necessary for Python.
f.add_rule(seccomp.ALLOW, "brk")
f.add_rule(seccomp.ALLOW, "exit_group")
f.add_rule(seccomp.ALLOW, "ioctl")
f.add_rule(seccomp.ALLOW, "mmap")
f.add_rule(seccomp.ALLOW, "munmap")
f.add_rule(seccomp.ALLOW, "rt_sigaction")
f.add_rule(seccomp.ALLOW, "rt_sigreturn")
# Mostly harmless.
f.add_rule(seccomp.ALLOW, "mprotect")
# Allow reading from stdin and writing to stdout/stderr.
f.add_rule(seccomp.ALLOW, "read", seccomp.Arg(0, seccomp.EQ, sys.stdin.fileno()))
f.add_rule(seccomp.ALLOW, "write", seccomp.Arg(0, seccomp.EQ, sys.stdout.fileno()))
f.add_rule(seccomp.ALLOW, "write", seccomp.Arg(0, seccomp.EQ, sys.stderr.fileno()))
# Needed for finding source code for exceptions.
f.add_rule(seccomp.ALLOW, "stat")
f.add_rule(seccomp.ALLOW, "open", seccomp.Arg(1, seccomp.MASKED_EQ, 0x3, 0)) # O_RDONLY
f.add_rule(seccomp.ALLOW, "close")
f.add_rule(seccomp.ALLOW, "read")
f.add_rule(seccomp.ALLOW, "fstat")
f.add_rule(seccomp.ALLOW, "lseek")
f.add_rule(seccomp.ALLOW, "fcntl")
# Needed for help().
f.add_rule(seccomp.ALLOW, "openat", seccomp.Arg(2, seccomp.MASKED_EQ, 0x3, 0)) # O_RDONLY
f.add_rule(seccomp.ALLOW, "getdents")
f.add_rule(seccomp.ALLOW, "getrlimit", seccomp.Arg(0, seccomp.EQ, 3)) # RLIMIT_STACK
f.add_rule(seccomp.ALLOW, "getrlimit", seccomp.Arg(0, seccomp.EQ, 7)) # RLIMIT_NOFILE
# Needed for code.InteractiveConsole.
f.add_rule(seccomp.ALLOW, "access")
f.add_rule(seccomp.ALLOW, "select")
f.load()
if len(sys.argv) > 1 and sys.argv[1] == 'run':
# Receive a pickled tuple (code, expr, stdin) on standard input, run it,
# and print a pickled tuple (result, out, err, exc) on standard output.
data = sys.stdin.buffer.read()
code, expr, stdin = pickle.loads(data)
result, out, err, exc = None, None, None, None
try:
sys.stdin = io.StringIO(stdin)
sys.stdout = io.StringIO()
sys.stderr = io.StringIO()
env = {}
if code:
exec(code, env)
if expr:
result = eval(expr, env)
except Exception as ex:
# Exception is not JSON serializable, so return traceback as string
# (without the first entry, which is this function).
import traceback
e_type, e_value, e_tb = sys.exc_info()
stack = traceback.extract_tb(e_tb)
exc = ''.join(
['Traceback (most recent call last):\n'] +
[' line {}, in {}\n'.format(lineno, name) + (line+'\n' if line else '')
for filename, lineno, name, line in stack[1:]] +
traceback.format_exception_only(e_type, e_value)
).rstrip()
finally:
out = sys.stdout.getvalue()
err = sys.stderr.getvalue()
sys.stdin.close()
sys.stdout.close()
sys.stderr.close()
outdata = pickle.dumps((result, out, err, exc))
sys.__stdout__.buffer.write(outdata)
else:
# Run an interactive console.
class MyConsole(code.InteractiveConsole):
def interact(self, banner=None):
if banner is not None:
self.write('{}\n'.format(banner))
buffer = []
prompt = '>>> '
while True:
try:
line = input(prompt)
# Assume we are running the user's program; silence the prompt.
if line == 'exec("""\\':
self.write('<run>\n')
prompt = ''
buffer.append(line)
source = '\n'.join(buffer)
more = self.runsource(source)
if more:
if prompt:
prompt = '... '
else:
prompt = '>>> '
buffer = []
except KeyboardInterrupt:
prompt = '>>> '
buffer = []
self.write('\n')
except ValueError:
break
except EOFError:
break
def runcode(self, code):
try:
exec(code, self.locals)
except KeyboardInterrupt:
self.write('^C')
raise
except SystemExit as ex:
raise
except:
# Show traceback for all other exceptions.
self.showtraceback()
MyConsole().interact()
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