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credstash-local.py
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credstash-local.py
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#!/usr/bin/env python
# Copyright 2015 Luminal, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import argparse
import boto.kms
import csv
import json
import operator
import os
import os.path
import sys
import time
import re
import boto3
try:
from StringIO import StringIO
except ImportError:
from io import StringIO
try:
import yaml
NO_YAML = False
except ImportError:
NO_YAML = True
from base64 import b64encode, b64decode
from boto.kms.exceptions import InvalidCiphertextException
from Crypto.Cipher import AES
from Crypto.Hash import SHA256
from Crypto.Hash.HMAC import HMAC
from Crypto.Util import Counter
DEFAULT_REGION = "us-east-1"
WILDCARD_CHAR = "*"
class KmsError(Exception):
def __init__(self, value=""):
self.value = "KMS ERROR: " + value if value is not "" else "KMS ERROR"
def __str__(self):
return self.value
class IntegrityError(Exception):
def __init__(self, value=""):
self.value = "INTEGRITY ERROR: " + value if value is not "" else \
"INTEGRITY ERROR"
def __str__(self):
return self.value
class KeyValueToDictionary(argparse.Action):
def __call__(self, parser, namespace, values, option_string=None):
setattr(namespace,
self.dest,
dict((x[0], x[1]) for x in values))
def printStdErr(s):
sys.stderr.write(str(s))
sys.stderr.write("\n")
def key_value_pair(string):
output = string.split('=')
if len(output) != 2:
msg = "%r is not the form of \"key=value\"" % string
raise argparse.ArgumentTypeError(msg)
return output
def expand_wildcard(string, secrets):
prog = re.compile('^' + string.replace(WILDCARD_CHAR, '.*') + '$')
output = []
for secret in secrets:
if prog.search(secret) is not None:
output.append(secret)
return output
def value_or_filename(string):
# argparse running on old version of python (<2.7) will pass an empty
# string to this function before it passes the actual value.
# If an empty string is passes in, just return an empty string
if string == "":
return ""
if string[0] == "@":
filename = string[1:]
try:
with open(os.path.expanduser(filename)) as f:
output = f.read()
except IOError as e:
raise argparse.ArgumentTypeError("Unable to read file %s" %
filename)
else:
output = string
return output
def csv_dump(dictionary):
csvfile = StringIO()
csvwriter = csv.writer(csvfile)
for key in dictionary:
csvwriter.writerow([key, dictionary[key]])
return csvfile.getvalue()
def putSecret(name, secret, version, kms_key="alias/credstash",
region="us-east-1", context=None):
'''
put a secret called `name` into the secret-store,
protected by the key kms_key
'''
if not context:
context = {}
kms = boto3.client('kms', region_name=region)
# generate a a 64 byte key.
# Half will be for data encryption, the other half for HMAC
# try:
kms_response = kms.generate_data_key(KeyId=kms_key, EncryptionContext=context, NumberOfBytes=64)
# except:
# raise KmsError("Could not generate key using KMS key %s" % kms_key)
data_key = kms_response['Plaintext'][:32]
hmac_key = kms_response['Plaintext'][32:]
wrapped_key = kms_response['CiphertextBlob']
enc_ctr = Counter.new(128)
encryptor = AES.new(data_key, AES.MODE_CTR, counter=enc_ctr)
c_text = encryptor.encrypt(secret)
# compute an HMAC using the hmac key and the ciphertext
hmac = HMAC(hmac_key, msg=c_text, digestmod=SHA256)
b64hmac = hmac.hexdigest()
data = {}
data['name'] = name
data['version'] = version if version != "" else "1"
data['key'] = b64encode(wrapped_key).decode('utf-8')
data['contents'] = b64encode(c_text).decode('utf-8')
data['hmac'] = b64hmac
with open('{0}.{1}.json'.format(name,data['version']), 'w') as fp:
json.dump(data, fp)
def getSecret(name, version="", region="us-east-1",
table="credential-store", context=None):
'''
fetch and decrypt the secret called `name`
'''
if not context:
context = {}
if version == "":
# do a consistent fetch of the credential with the highest version
# list all files matching pattern
pass
# if not result_set:
# raise ItemNotFound("Item {'name': '%s'} couldn't be found." % name)
# material = result_set[0]
with open("{0}.{1}.json".format(name, version), 'r') as fp:
material = json.load(fp)
kms = boto3.client('kms', region_name=region)
# Check the HMAC before we decrypt to verify ciphertext integrity
try:
kms_response = kms.decrypt(CiphertextBlob=b64decode(material['key']), EncryptionContext=context)
except InvalidCiphertextException:
if context is None:
msg = ("Could not decrypt hmac key with KMS. The credential may "
"require that an encryption context be provided to decrypt "
"it.")
else:
msg = ("Could not decrypt hmac key with KMS. The encryption "
"context provided may not match the one used when the "
"credential was stored.")
raise KmsError(msg)
except Exception as e:
raise KmsError("Decryption error %s" % e)
key = kms_response['Plaintext'][:32]
hmac_key = kms_response['Plaintext'][32:]
hmac = HMAC(hmac_key, msg=b64decode(material['contents']),
digestmod=SHA256)
if hmac.hexdigest() != material['hmac']:
raise IntegrityError("Computed HMAC on %s does not match stored HMAC"
% name)
dec_ctr = Counter.new(128)
decryptor = AES.new(key, AES.MODE_CTR, counter=dec_ctr)
plaintext = decryptor.decrypt(b64decode(material['contents'])).decode("utf-8")
return plaintext
def deleteSecrets(name, region="us-east-1"):
pass
def main():
parsers = {}
parsers['super'] = argparse.ArgumentParser(
description="A credential/secret storage system")
parsers['super'].add_argument("-r", "--region",
help="the AWS region in which to operate."
"If a region is not specified, credstash "
"will use the value of the "
"AWS_DEFAULT_REGION env variable, "
"or if that is not set, us-east-1")
subparsers = parsers['super'].add_subparsers(help='Try commands like '
'"{name} get -h" or "{name}'
'put --help" to get each'
'sub command\'s options'
.format(name=os.path.basename(
__file__)))
action = 'delete'
parsers[action] = subparsers.add_parser(action,
help='Delete a credential " \
"from the store')
parsers[action].add_argument("credential", type=str,
help="the name of the credential to delete")
parsers[action].set_defaults(action=action)
action = 'get'
parsers[action] = subparsers.add_parser(action, help="Get a credential "
"from the store")
parsers[action].add_argument("credential", type=str,
help="the name of the credential to get."
"Using the wildcard character '%s' will "
"search for credentials that match the "
"pattern" % WILDCARD_CHAR)
parsers[action].add_argument("context", type=key_value_pair,
action=KeyValueToDictionary, nargs='*',
help="encryption context key/value pairs "
"associated with the credential in the form "
"of \"key=value\"")
parsers[action].add_argument("-n", "--noline", action="store_true",
help="Don't append newline to returned "
"value (useful in scripts or with "
"binary files)")
parsers[action].add_argument("-v", "--version", default="",
help="Get a specific version of the "
"credential (defaults to the latest version)")
parsers[action].set_defaults(action=action)
action = 'getall'
parsers[action] = subparsers.add_parser(action,
help="Get all credentials from "
"the store")
parsers[action].add_argument("context", type=key_value_pair,
action=KeyValueToDictionary, nargs='*',
help="encryption context key/value pairs "
"associated with the credential in the form "
"of \"key=value\"")
parsers[action].add_argument("-v", "--version", default="",
help="Get a specific version of the "
"credential (defaults to the latest version)")
parsers[action].add_argument("-f", "--format", default="json",
choices=["json", "csv"] +
([] if NO_YAML else ["yaml"]),
help="Output format. json(default) " +
("" if NO_YAML else "yaml ") + "or csv.")
parsers[action].set_defaults(action=action)
action = 'list'
parsers[action] = subparsers.add_parser(action,
help="list credentials and "
"their versions")
parsers[action].set_defaults(action=action)
action = 'put'
parsers[action] = subparsers.add_parser(action,
help="Put a credential into "
"the store")
parsers[action].add_argument("credential", type=str,
help="the name of the credential to store")
parsers[action].add_argument("value", type=value_or_filename,
help="the value of the credential to store "
"or, if beginning with the \"@\" character, "
"the filename of the file containing "
"the value", default="")
parsers[action].add_argument("context", type=key_value_pair,
action=KeyValueToDictionary, nargs='*',
help="encryption context key/value pairs "
"associated with the credential in the form "
"of \"key=value\"")
parsers[action].add_argument("-k", "--key", default="alias/credstash",
help="the KMS key-id of the master key "
"to use. See the README for more "
"information. Defaults to alias/credstash")
parsers[action].add_argument("-v", "--version", default="",
help="Put a specific version of the "
"credential (update the credential; "
"defaults to version `1`).")
parsers[action].set_defaults(action=action)
action = 'setup'
parsers[action] = subparsers.add_parser(action,
help='setup the credential store')
parsers[action].set_defaults(action=action)
args = parsers['super'].parse_args()
region = os.getenv(
"AWS_DEFAULT_REGION", DEFAULT_REGION) if not args.region \
else args.region
if "action" in vars(args):
if args.action == "delete":
deleteSecrets(args.credential, region=region, table=args.table)
return
if args.action == "list":
credential_list = listSecrets(region=region, table=args.table)
if credential_list:
# print list of credential names and versions,
# sorted by name and then by version
max_len = max([len(x["name"]) for x in credential_list])
for cred in sorted(credential_list,
key=operator.itemgetter("name", "version")):
print("{0:{1}} -- version {2:>}".format(
cred["name"], max_len, cred["version"]))
else:
return
if args.action == "put":
try:
if putSecret(args.credential, args.value, args.version,
kms_key=args.key, region=region,
context=args.context):
print("{0} has been stored".format(args.credential))
except KmsError as e:
printStdErr(e)
# except ConditionalCheckFailedException:
# latestVersion = getHighestVersion(args.credential, region,
# args.table)
# printStdErr("%s version %s is already in the credential store."
# "Use the -v flag to specify a new version" %
# (args.credential, latestVersion))
return
if args.action == "get":
try:
if WILDCARD_CHAR in args.credential:
names = expand_wildcard(args.credential,
[x["name"]
for x
in listSecrets(region=region)])
print(json.dumps(dict((name,
getSecret(name,
args.version,
region=region,
context=args.context))
for name in names)))
else:
sys.stdout.write(getSecret(args.credential, args.version,
region=region,
context=args.context))
if not args.noline:
sys.stdout.write("\n")
except KmsError as e:
printStdErr(e)
except IntegrityError as e:
printStdErr(e)
return
if args.action == "getall":
secrets = getAllSecrets(args.version,
region=region,
table=args.table,
context=args.context)
if args.format == "json":
output_func = json.dumps
output_args = {"sort_keys": True,
"indent": 4,
"separators": (',', ': ')}
elif not NO_YAML and args.format == "yaml":
output_func = yaml.dump
output_args = {"default_flow_style": False}
elif args.format == 'csv':
output_func = csv_dump
output_args = {}
print(output_func(secrets, **output_args))
return
if args.action == "setup":
return
else:
parsers['super'].print_help()
if __name__ == '__main__':
main()