epicyon/auth.py

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__filename__ = "auth.py"
__author__ = "Bob Mottram"
__license__ = "AGPL3+"
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__version__ = "1.2.0"
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__maintainer__ = "Bob Mottram"
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__email__ = "bob@libreserver.org"
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__status__ = "Production"
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__module_group__ = "Security"
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import base64
import hashlib
import binascii
import os
import secrets
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import datetime
from utils import isSystemAccount
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from utils import hasUsersPath
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def _hashPassword(password: str) -> str:
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"""Hash a password for storing
"""
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salt = hashlib.sha256(os.urandom(60)).hexdigest().encode('ascii')
pwdhash = hashlib.pbkdf2_hmac('sha512',
password.encode('utf-8'),
salt, 100000)
pwdhash = binascii.hexlify(pwdhash)
return (salt + pwdhash).decode('ascii')
def _getPasswordHash(salt: str, providedPassword: str) -> str:
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"""Returns the hash of a password
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"""
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pwdhash = hashlib.pbkdf2_hmac('sha512',
providedPassword.encode('utf-8'),
salt.encode('ascii'),
100000)
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return binascii.hexlify(pwdhash).decode('ascii')
def constantTimeStringCheck(string1: str, string2: str) -> bool:
"""Compares two string and returns if they are the same
using a constant amount of time
See https://sqreen.github.io/DevelopersSecurityBestPractices/
timing-attack/python
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"""
# strings must be of equal length
if len(string1) != len(string2):
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return False
ctr = 0
matched = True
for ch in string1:
if ch != string2[ctr]:
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matched = False
else:
# this is to make the timing more even
# and not provide clues
matched = matched
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ctr += 1
return matched
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def _verifyPassword(storedPassword: str, providedPassword: str) -> bool:
"""Verify a stored password against one provided by user
"""
if not storedPassword:
return False
if not providedPassword:
return False
salt = storedPassword[:64]
storedPassword = storedPassword[64:]
pwHash = _getPasswordHash(salt, providedPassword)
return constantTimeStringCheck(pwHash, storedPassword)
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def createBasicAuthHeader(nickname: str, password: str) -> str:
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"""This is only used by tests
"""
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authStr = \
nickname.replace('\n', '').replace('\r', '') + \
':' + \
password.replace('\n', '').replace('\r', '')
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return 'Basic ' + base64.b64encode(authStr.encode('utf-8')).decode('utf-8')
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def authorizeBasic(base_dir: str, path: str, authHeader: str,
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debug: bool) -> bool:
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"""HTTP basic auth
"""
if ' ' not in authHeader:
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if debug:
print('DEBUG: basic auth - Authorisation header does not ' +
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'contain a space character')
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return False
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if not hasUsersPath(path):
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if debug:
print('DEBUG: basic auth - ' +
'path for Authorization does not contain a user')
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return False
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pathUsersSection = path.split('/users/')[1]
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if '/' not in pathUsersSection:
if debug:
print('DEBUG: basic auth - this is not a users endpoint')
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return False
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nicknameFromPath = pathUsersSection.split('/')[0]
if isSystemAccount(nicknameFromPath):
print('basic auth - attempted login using system account ' +
nicknameFromPath + ' in path')
return False
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base64Str = \
authHeader.split(' ')[1].replace('\n', '').replace('\r', '')
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plain = base64.b64decode(base64Str).decode('utf-8')
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if ':' not in plain:
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if debug:
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print('DEBUG: basic auth header does not contain a ":" ' +
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'separator for username:password')
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return False
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nickname = plain.split(':')[0]
if isSystemAccount(nickname):
print('basic auth - attempted login using system account ' + nickname +
' in Auth header')
return False
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if nickname != nicknameFromPath:
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if debug:
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print('DEBUG: Nickname given in the path (' + nicknameFromPath +
') does not match the one in the Authorization header (' +
nickname + ')')
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return False
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passwordFile = base_dir + '/accounts/passwords'
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if not os.path.isfile(passwordFile):
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if debug:
print('DEBUG: passwords file missing')
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return False
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providedPassword = plain.split(':')[1]
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try:
with open(passwordFile, 'r') as passfile:
for line in passfile:
if not line.startswith(nickname + ':'):
continue
storedPassword = \
line.split(':')[1].replace('\n', '').replace('\r', '')
success = _verifyPassword(storedPassword, providedPassword)
if not success:
if debug:
print('DEBUG: Password check failed for ' + nickname)
return success
except OSError:
print('EX: failed to open password file')
return False
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print('DEBUG: Did not find credentials for ' + nickname +
' in ' + passwordFile)
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return False
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def storeBasicCredentials(base_dir: str, nickname: str, password: str) -> bool:
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"""Stores login credentials to a file
"""
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if ':' in nickname or ':' in password:
return False
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nickname = nickname.replace('\n', '').replace('\r', '').strip()
password = password.replace('\n', '').replace('\r', '').strip()
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if not os.path.isdir(base_dir + '/accounts'):
os.mkdir(base_dir + '/accounts')
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passwordFile = base_dir + '/accounts/passwords'
storeStr = nickname + ':' + _hashPassword(password)
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if os.path.isfile(passwordFile):
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if nickname + ':' in open(passwordFile).read():
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try:
with open(passwordFile, 'r') as fin:
with open(passwordFile + '.new', 'w+') as fout:
for line in fin:
if not line.startswith(nickname + ':'):
fout.write(line)
else:
fout.write(storeStr + '\n')
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except OSError as ex:
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print('EX: unable to save password ' + passwordFile +
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' ' + str(ex))
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return False
try:
os.rename(passwordFile + '.new', passwordFile)
except OSError:
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print('EX: unable to save password 2')
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return False
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else:
# append to password file
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try:
with open(passwordFile, 'a+') as passfile:
passfile.write(storeStr + '\n')
except OSError:
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print('EX: unable to append password')
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return False
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else:
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try:
with open(passwordFile, 'w+') as passfile:
passfile.write(storeStr + '\n')
except OSError:
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print('EX: unable to create password file')
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return False
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return True
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def removePassword(base_dir: str, nickname: str) -> None:
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"""Removes the password entry for the given nickname
This is called during account removal
"""
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passwordFile = base_dir + '/accounts/passwords'
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if os.path.isfile(passwordFile):
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try:
with open(passwordFile, 'r') as fin:
with open(passwordFile + '.new', 'w+') as fout:
for line in fin:
if not line.startswith(nickname + ':'):
fout.write(line)
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except OSError as ex:
print('EX: unable to remove password from file ' + str(ex))
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return
try:
os.rename(passwordFile + '.new', passwordFile)
except OSError:
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print('EX: unable to remove password from file 2')
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return
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def authorize(base_dir: str, path: str, authHeader: str, debug: bool) -> bool:
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"""Authorize using http header
"""
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if authHeader.lower().startswith('basic '):
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return authorizeBasic(base_dir, path, authHeader, debug)
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return False
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def createPassword(length: int):
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validChars = 'abcdefghijklmnopqrstuvwxyz' + \
'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
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return ''.join((secrets.choice(validChars) for i in range(length)))
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def recordLoginFailure(base_dir: str, ipAddress: str,
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countDict: {}, failTime: int,
logToFile: bool) -> None:
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"""Keeps ip addresses and the number of times login failures
occured for them in a dict
"""
if not countDict.get(ipAddress):
while len(countDict.items()) > 100:
oldestTime = 0
oldestIP = None
for ipAddr, ipItem in countDict.items():
if oldestTime == 0 or ipItem['time'] < oldestTime:
oldestTime = ipItem['time']
oldestIP = ipAddr
if oldestIP:
del countDict[oldestIP]
countDict[ipAddress] = {
"count": 1,
"time": failTime
}
else:
countDict[ipAddress]['count'] += 1
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countDict[ipAddress]['time'] = failTime
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failCount = countDict[ipAddress]['count']
if failCount > 4:
print('WARN: ' + str(ipAddress) + ' failed to log in ' +
str(failCount) + ' times')
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if not logToFile:
return
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failureLog = base_dir + '/accounts/loginfailures.log'
writeType = 'a+'
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if not os.path.isfile(failureLog):
writeType = 'w+'
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currTime = datetime.datetime.utcnow()
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currTimeStr = currTime.strftime("%Y-%m-%d %H:%M:%SZ")
try:
with open(failureLog, writeType) as fp:
# here we use a similar format to an ssh log, so that
# systems such as fail2ban can parse it
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fp.write(currTimeStr + ' ' +
'ip-127-0-0-1 sshd[20710]: ' +
'Disconnecting invalid user epicyon ' +
ipAddress + ' port 443: ' +
'Too many authentication failures [preauth]\n')
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except OSError:
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print('EX: recordLoginFailure failed ' + str(failureLog))