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tools/qvm-start: validate output of losetup command

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QubesOS/qubes-issues#4860
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Marek Marczykowski-Górecki 2019-02-28 06:19:56 +01:00
parent a2629b1239
commit fb910a71cf
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GPG Key ID: 063938BA42CFA724
1 changed files with 12 additions and 2 deletions
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14
qubesadmin/tools/qvm_start.py
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@ -20,6 +20,7 @@
'''qvm-start - start a domain''' '''qvm-start - start a domain'''
import argparse import argparse
import string
import sys import sys
import subprocess import subprocess
@ -114,14 +115,23 @@ def get_drive_assignment(app, drive_str):
if backend_domain.klass == 'AdminVM': if backend_domain.klass == 'AdminVM':
loop_name = subprocess.check_output( loop_name = subprocess.check_output(
['sudo', 'losetup', '-f', '--show', ident]) ['sudo', 'losetup', '-f', '--show', ident])
loop_name = loop_name.strip()
else: else:
loop_name, _ = backend_domain.run_with_args( untrusted_loop_name, _ = backend_domain.run_with_args(
'losetup', '-f', '--show', ident, 'losetup', '-f', '--show', ident,
user='root') user='root')
untrusted_loop_name = untrusted_loop_name.strip()
allowed_chars = string.ascii_lowercase + string.digits + '/'
allowed_chars = allowed_chars.encode('ascii')
if not all(c in allowed_chars for c in untrusted_loop_name):
raise qubesadmin.exc.QubesException(
'Invalid loop device name received from {}'.format(
backend_domain.name))
loop_name = untrusted_loop_name
del untrusted_loop_name
except subprocess.CalledProcessError: except subprocess.CalledProcessError:
raise qubesadmin.exc.QubesException( raise qubesadmin.exc.QubesException(
'Failed to setup loop device for %s', ident) 'Failed to setup loop device for %s', ident)
loop_name = loop_name.strip()
assert loop_name.startswith(b'/dev/loop') assert loop_name.startswith(b'/dev/loop')
ident = loop_name.decode().split('/')[2] ident = loop_name.decode().split('/')[2]
# wait for device to appear # wait for device to appear