def test_validate_multiple_principals(test_input):
BlessSchema().validate_remote_usernames(test_input)
schema = BlessSchema()
schema.context[USERNAME_VALIDATION_OPTION] = USERNAME_VALIDATION_OPTIONS.principal.name
schema.context[REMOTE_USERNAMES_VALIDATION_OPTION] = USERNAME_VALIDATION_OPTIONS.principal.name
schema.context[REMOTE_USERNAMES_BLACKLIST_OPTION] = 'balrog'
schema.validate_remote_usernames(test_input)
def lambda_handler(event,
context=None,
ca_private_key_password=None,
entropy_check=True,
config_file=os.path.join(os.path.dirname(__file__),
'bless_deploy.cfg')):
"""
This is the function that will be called when the lambda function starts.
:param event: Dictionary of the json request.
:param context: AWS LambdaContext Object
http://docs.aws.amazon.com/lambda/latest/dg/python-context-object.html
:param ca_private_key_password: For local testing, if the password is provided, skip the KMS
decrypt.
:param entropy_check: For local testing, if set to false, it will skip checking entropy and
won't try to fetch additional random from KMS
:param config_file: The config file to load the SSH CA private key from, and additional settings
:return: the SSH Certificate that can be written to id_rsa-cert.pub or similar file.
"""
# AWS Region determines configs related to KMS
region = os.environ['AWS_REGION']
# Load the deployment config values
config = BlessConfig(region, config_file=config_file)
logging_level = config.get(BLESS_OPTIONS_SECTION, LOGGING_LEVEL_OPTION)
numeric_level = getattr(logging, logging_level.upper(), None)
if not isinstance(numeric_level, int):
raise ValueError('Invalid log level: {}'.format(logging_level))
logger = logging.getLogger()
logger.setLevel(numeric_level)
certificate_validity_before_seconds = config.getint(
BLESS_OPTIONS_SECTION, CERTIFICATE_VALIDITY_BEFORE_SEC_OPTION)
certificate_validity_after_seconds = config.getint(
BLESS_OPTIONS_SECTION, CERTIFICATE_VALIDITY_AFTER_SEC_OPTION)
entropy_minimum_bits = config.getint(BLESS_OPTIONS_SECTION,
ENTROPY_MINIMUM_BITS_OPTION)
random_seed_bytes = config.getint(BLESS_OPTIONS_SECTION,
RANDOM_SEED_BYTES_OPTION)
ca_private_key = config.getprivatekey()
password_ciphertext_b64 = config.getpassword()
certificate_extensions = config.get(BLESS_OPTIONS_SECTION,
CERTIFICATE_EXTENSIONS_OPTION)
# Process cert request
schema = BlessSchema(strict=True)
schema.context[USERNAME_VALIDATION_OPTION] = config.get(
BLESS_OPTIONS_SECTION, USERNAME_VALIDATION_OPTION)
schema.context[REMOTE_USERNAMES_VALIDATION_OPTION] = config.get(
BLESS_OPTIONS_SECTION, REMOTE_USERNAMES_VALIDATION_OPTION)
try:
request = schema.load(event).data
except ValidationError as e:
return error_response('InputValidationError', str(e))
logger.info(
'Bless lambda invoked by [user: {0}, bastion_ips:{1}, public_key: {2}, kmsauth_token:{3}]'
.format(request.bastion_user, request.bastion_user_ip,
request.public_key_to_sign, request.kmsauth_token))
# decrypt ca private key password
if ca_private_key_password is None:
kms_client = boto3.client('kms', region_name=region)
try:
ca_password = kms_client.decrypt(
CiphertextBlob=base64.b64decode(password_ciphertext_b64))
ca_private_key_password = ca_password['Plaintext']
except ClientError as e:
return error_response('ClientError', str(e))
# if running as a Lambda, we can check the entropy pool and seed it with KMS if desired
if entropy_check:
with open('/proc/sys/kernel/random/entropy_avail', 'r') as f:
entropy = int(f.read())
logger.debug(entropy)
if entropy < entropy_minimum_bits:
logger.info(
'System entropy was {}, which is lower than the entropy_'
'minimum {}. Using KMS to seed /dev/urandom'.format(
entropy, entropy_minimum_bits))
response = kms_client.generate_random(
NumberOfBytes=random_seed_bytes)
random_seed = response['Plaintext']
with open('/dev/urandom', 'w') as urandom:
urandom.write(random_seed)
# cert values determined only by lambda and its configs
current_time = int(time.time())
test_user = config.get(BLESS_OPTIONS_SECTION, TEST_USER_OPTION)
if test_user and (request.bastion_user == test_user
or request.remote_usernames == test_user):
# This is a test call, the lambda will issue an invalid
# certificate where valid_before < valid_after
valid_before = current_time
valid_after = current_time + 1
bypass_time_validity_check = True
else:
valid_before = current_time + certificate_validity_after_seconds
valid_after = current_time - certificate_validity_before_seconds
bypass_time_validity_check = False
# Authenticate the user with KMS, if key is setup
if config.get(KMSAUTH_SECTION, KMSAUTH_USEKMSAUTH_OPTION):
if request.kmsauth_token:
try:
validator = KMSTokenValidator(
None, config.getkmsauthkeyids(),
config.get(KMSAUTH_SECTION, KMSAUTH_SERVICE_ID_OPTION),
region)
# decrypt_token will raise a TokenValidationError if token doesn't match
validator.decrypt_token(
"2/user/{}".format(request.remote_usernames),
request.kmsauth_token)
except TokenValidationError as e:
return error_response('KMSAuthValidationError', str(e))
else:
return error_response('InputValidationError',
'Invalid request, missing kmsauth token')
# Build the cert
ca = get_ssh_certificate_authority(ca_private_key, ca_private_key_password)
cert_builder = get_ssh_certificate_builder(ca, SSHCertificateType.USER,
request.public_key_to_sign)
for username in request.remote_usernames.split(','):
cert_builder.add_valid_principal(username)
cert_builder.set_valid_before(valid_before)
cert_builder.set_valid_after(valid_after)
if certificate_extensions:
for e in certificate_extensions.split(','):
if e:
cert_builder.add_extension(e)
else:
cert_builder.clear_extensions()
# cert_builder is needed to obtain the SSH public key's fingerprint
key_id = 'request[{}] for[{}] from[{}] command[{}] ssh_key[{}] ca[{}] valid_to[{}]'.format(
context.aws_request_id, request.bastion_user, request.bastion_user_ip,
request.command, cert_builder.ssh_public_key.fingerprint,
context.invoked_function_arn,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_before)))
cert_builder.set_critical_option_source_addresses(request.bastion_ips)
cert_builder.set_key_id(key_id)
cert = cert_builder.get_cert_file(bypass_time_validity_check)
logger.info(
'Issued a cert to bastion_ips[{}] for remote_usernames[{}] with key_id[{}] and '
'valid_from[{}])'.format(
request.bastion_ips, request.remote_usernames, key_id,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_after))))
return success_response(cert)
def test_invalid_user_with_default_context_of_useradd():
with pytest.raises(ValidationError) as e:
BlessSchema().validate_bastion_user('user#invalid')
assert e.value.message == 'Username contains invalid characters.'
def test_invalid_multiple_principals(test_input):
with pytest.raises(ValidationError) as e:
BlessSchema().validate_remote_usernames(test_input)
assert e.value.message == 'Principal contains invalid characters.'
def lambda_handler(event,
context=None,
ca_private_key_password=None,
entropy_check=True,
config_file=os.path.join(os.path.dirname(__file__),
'bless_deploy.cfg')):
"""
This is the function that will be called when the lambda function starts.
:param event: Dictionary of the json request.
:param context: AWS LambdaContext Object
http://docs.aws.amazon.com/lambda/latest/dg/python-context-object.html
:param ca_private_key_password: For local testing, if the password is provided, skip the KMS
decrypt.
:param entropy_check: For local testing, if set to false, it will skip checking entropy and
won't try to fetch additional random from KMS
:param config_file: The config file to load the SSH CA private key from, and additional settings
:return: the SSH Certificate that can be written to id_rsa-cert.pub or similar file.
"""
# AWS Region determines configs related to KMS
region = os.environ['AWS_REGION']
# Load the deployment config values
config = BlessConfig(region, config_file=config_file)
logging_level = config.get(BLESS_OPTIONS_SECTION, LOGGING_LEVEL_OPTION)
numeric_level = getattr(logging, logging_level.upper(), None)
if not isinstance(numeric_level, int):
raise ValueError('Invalid log level: {}'.format(logging_level))
logger = logging.getLogger()
logger.setLevel(numeric_level)
certificate_validity_window_seconds = config.getint(
BLESS_OPTIONS_SECTION, CERTIFICATE_VALIDITY_WINDOW_SEC_OPTION)
entropy_minimum_bits = config.getint(BLESS_OPTIONS_SECTION,
ENTROPY_MINIMUM_BITS_OPTION)
random_seed_bytes = config.getint(BLESS_OPTIONS_SECTION,
RANDOM_SEED_BYTES_OPTION)
ca_private_key_file = config.get(BLESS_CA_SECTION,
CA_PRIVATE_KEY_FILE_OPTION)
password_ciphertext_b64 = config.getpassword()
# read the private key .pem
with open(os.path.join(os.path.dirname(__file__), ca_private_key_file),
'r') as f:
ca_private_key = f.read()
# decrypt ca private key password
if ca_private_key_password is None:
kms_client = boto3.client('kms', region_name=region)
ca_password = kms_client.decrypt(
CiphertextBlob=base64.b64decode(password_ciphertext_b64))
ca_private_key_password = ca_password['Plaintext']
# if running as a Lambda, we can check the entropy pool and seed it with KMS if desired
if entropy_check:
with open('/proc/sys/kernel/random/entropy_avail', 'r') as f:
entropy = int(f.read())
logger.debug(entropy)
if entropy < entropy_minimum_bits:
logger.info(
'System entropy was {}, which is lower than the entropy_'
'minimum {}. Using KMS to seed /dev/urandom'.format(
entropy, entropy_minimum_bits))
response = kms_client.generate_random(
NumberOfBytes=random_seed_bytes)
random_seed = response['Plaintext']
with open('/dev/urandom', 'w') as urandom:
urandom.write(random_seed)
# Process cert request
schema = BlessSchema(strict=True)
request = schema.load(event).data
# cert values determined only by lambda and its configs
current_time = int(time.time())
valid_before = current_time + certificate_validity_window_seconds
valid_after = current_time - certificate_validity_window_seconds
# Build the cert
ca = get_ssh_certificate_authority(ca_private_key, ca_private_key_password)
cert_builder = get_ssh_certificate_builder(ca, SSHCertificateType.USER,
request.public_key_to_sign)
cert_builder.add_valid_principal(request.remote_username)
cert_builder.set_valid_before(valid_before)
cert_builder.set_valid_after(valid_after)
# cert_builder is needed to obtain the ssh public key's fingerprint
key_id = 'request[{}] for[{}] from[{}] command[{}] ssh_key:[{}] ca:[{}] valid_to[{}]'.format(
context.aws_request_id, request.bastion_user, request.bastion_user_ip,
request.command, cert_builder.ssh_public_key.fingerprint,
context.invoked_function_arn,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_before)))
cert_builder.set_critical_option_source_address(request.bastion_ip)
cert_builder.set_key_id(key_id)
cert = cert_builder.get_cert_file()
logger.info(
'Issued a cert to bastion_ip[{}] for the remote_username of [{}] with the key_id[{}] and '
'valid_from[{}])'.format(
request.bastion_ip, request.remote_username, key_id,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_after))))
return cert
def lambda_handler(event, context=None, ca_private_key_password=None,
entropy_check=True,
config_file=os.path.join(os.path.dirname(__file__), 'bless_deploy.cfg')):
"""
This is the function that will be called when the lambda function starts.
:param event: Dictionary of the json request.
:param context: AWS LambdaContext Object
http://docs.aws.amazon.com/lambda/latest/dg/python-context-object.html
:param ca_private_key_password: For local testing, if the password is provided, skip the KMS
decrypt.
:param entropy_check: For local testing, if set to false, it will skip checking entropy and
won't try to fetch additional random from KMS
:param config_file: The config file to load the SSH CA private key from, and additional settings
:return: the SSH Certificate that can be written to id_rsa-cert.pub or similar file.
"""
# AWS Region determines configs related to KMS
region = os.environ['AWS_REGION']
# Load the deployment config values
config = BlessConfig(region,
config_file=config_file)
logging_level = config.get(BLESS_OPTIONS_SECTION, LOGGING_LEVEL_OPTION)
numeric_level = getattr(logging, logging_level.upper(), None)
if not isinstance(numeric_level, int):
raise ValueError('Invalid log level: {}'.format(logging_level))
logger = logging.getLogger()
logger.setLevel(numeric_level)
certificate_validity_before_seconds = config.getint(BLESS_OPTIONS_SECTION,
CERTIFICATE_VALIDITY_BEFORE_SEC_OPTION)
certificate_validity_after_seconds = config.getint(BLESS_OPTIONS_SECTION,
CERTIFICATE_VALIDITY_AFTER_SEC_OPTION)
entropy_minimum_bits = config.getint(BLESS_OPTIONS_SECTION, ENTROPY_MINIMUM_BITS_OPTION)
random_seed_bytes = config.getint(BLESS_OPTIONS_SECTION, RANDOM_SEED_BYTES_OPTION)
ca_private_key = config.getprivatekey()
password_ciphertext_b64 = config.getpassword()
certificate_extensions = config.get(BLESS_OPTIONS_SECTION, CERTIFICATE_EXTENSIONS_OPTION)
# Process cert request
schema = BlessSchema(strict=True)
schema.context[USERNAME_VALIDATION_OPTION] = config.get(BLESS_OPTIONS_SECTION, USERNAME_VALIDATION_OPTION)
schema.context[REMOTE_USERNAMES_VALIDATION_OPTION] = config.get(BLESS_OPTIONS_SECTION,
REMOTE_USERNAMES_VALIDATION_OPTION)
try:
request = schema.load(event).data
except ValidationError as e:
return error_response('InputValidationError', str(e))
logger.info('Bless lambda invoked by [user: {0}, bastion_ips:{1}, public_key: {2}, kmsauth_token:{3}]'.format(
request.bastion_user,
request.bastion_user_ip,
request.public_key_to_sign,
request.kmsauth_token))
# decrypt ca private key password
if ca_private_key_password is None:
kms_client = boto3.client('kms', region_name=region)
try:
ca_password = kms_client.decrypt(
CiphertextBlob=base64.b64decode(password_ciphertext_b64))
ca_private_key_password = ca_password['Plaintext']
except ClientError as e:
return error_response('ClientError', str(e))
# if running as a Lambda, we can check the entropy pool and seed it with KMS if desired
if entropy_check:
with open('/proc/sys/kernel/random/entropy_avail', 'r') as f:
entropy = int(f.read())
logger.debug(entropy)
if entropy < entropy_minimum_bits:
logger.info(
'System entropy was {}, which is lower than the entropy_'
'minimum {}. Using KMS to seed /dev/urandom'.format(
entropy, entropy_minimum_bits))
response = kms_client.generate_random(
NumberOfBytes=random_seed_bytes)
random_seed = response['Plaintext']
with open('/dev/urandom', 'w') as urandom:
urandom.write(random_seed)
# cert values determined only by lambda and its configs
current_time = int(time.time())
test_user = config.get(BLESS_OPTIONS_SECTION, TEST_USER_OPTION)
if test_user and (request.bastion_user == test_user or request.remote_usernames == test_user):
# This is a test call, the lambda will issue an invalid
# certificate where valid_before < valid_after
valid_before = current_time
valid_after = current_time + 1
bypass_time_validity_check = True
else:
valid_before = current_time + certificate_validity_after_seconds
valid_after = current_time - certificate_validity_before_seconds
bypass_time_validity_check = False
# Authenticate the user with KMS, if key is setup
if config.get(KMSAUTH_SECTION, KMSAUTH_USEKMSAUTH_OPTION):
if request.kmsauth_token:
# Allow bless to sign the cert for a different remote user than the name of the user who signed it
allowed_remotes = config.get(KMSAUTH_SECTION, KMSAUTH_REMOTE_USERNAMES_ALLOWED_OPTION)
if allowed_remotes:
allowed_users = allowed_remotes.split(',')
requested_remotes = request.remote_usernames.split(',')
if allowed_users != ['*'] and not all([u in allowed_users for u in requested_remotes]):
return error_response('KMSAuthValidationError',
'unallowed remote_usernames [{}]'.format(request.remote_usernames))
elif request.remote_usernames != request.bastion_user:
return error_response('KMSAuthValidationError',
'remote_usernames must be the same as bastion_user')
try:
validator = KMSTokenValidator(
None,
config.getkmsauthkeyids(),
config.get(KMSAUTH_SECTION, KMSAUTH_SERVICE_ID_OPTION),
region
)
# decrypt_token will raise a TokenValidationError if token doesn't match
validator.decrypt_token(
"2/user/{}".format(request.bastion_user),
request.kmsauth_token
)
except TokenValidationError as e:
return error_response('KMSAuthValidationError', str(e))
else:
return error_response('InputValidationError', 'Invalid request, missing kmsauth token')
# Build the cert
ca = get_ssh_certificate_authority(ca_private_key, ca_private_key_password)
cert_builder = get_ssh_certificate_builder(ca, SSHCertificateType.USER,
request.public_key_to_sign)
for username in request.remote_usernames.split(','):
cert_builder.add_valid_principal(username)
cert_builder.set_valid_before(valid_before)
cert_builder.set_valid_after(valid_after)
if certificate_extensions:
for e in certificate_extensions.split(','):
if e:
cert_builder.add_extension(e)
else:
cert_builder.clear_extensions()
# cert_builder is needed to obtain the SSH public key's fingerprint
key_id = 'request[{}] for[{}] from[{}] command[{}] ssh_key[{}] ca[{}] valid_to[{}]'.format(
context.aws_request_id, request.bastion_user, request.bastion_user_ip, request.command,
cert_builder.ssh_public_key.fingerprint, context.invoked_function_arn,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_before)))
cert_builder.set_critical_option_source_addresses(request.bastion_ips)
cert_builder.set_key_id(key_id)
cert = cert_builder.get_cert_file(bypass_time_validity_check)
logger.info(
'Issued a cert to bastion_ips[{}] for remote_usernames[{}] with key_id[{}] and '
'valid_from[{}])'.format(
request.bastion_ips, request.remote_usernames, key_id,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_after))))
return success_response(cert)
def lambda_handler(event, context=None, ca_private_key_password=None, okta_api_token=None,
entropy_check=True,
config_file=os.path.join(os.path.dirname(__file__), 'bless_deploy.cfg')):
"""
This is the function that will be called when the lambda function starts.
:param event: Dictionary of the json request.
:param context: AWS LambdaContext Object
http://docs.aws.amazon.com/lambda/latest/dg/python-context-object.html
:param ca_private_key_password: For local testing, if the password is provided, skip the KMS
decrypt.
:param entropy_check: For local testing, if set to false, it will skip checking entropy and
won't try to fetch additional random from KMS
:param config_file: The config file to load the SSH CA private key from, and additional settings
:return: the SSH Certificate that can be written to id_rsa-cert.pub or similar file.
"""
# AWS Region determines configs related to KMS
region = os.environ['AWS_REGION']
# Load the deployment config values
config = BlessConfig(region, config_file=config_file)
logger = logging.getLogger(__name__)
logging_level = config.get(BLESS_OPTIONS_SECTION, LOGGING_LEVEL_OPTION)
numeric_level = getattr(logging, logging_level.upper(), None)
if not isinstance(numeric_level, int):
raise ValueError('Invalid log level: {}'.format(logging_level))
logger.setLevel(numeric_level)
certificate_validity_before_seconds = config.getint(BLESS_OPTIONS_SECTION, CERTIFICATE_VALIDITY_BEFORE_SEC_OPTION)
certificate_validity_after_seconds = config.getint(BLESS_OPTIONS_SECTION, CERTIFICATE_VALIDITY_AFTER_SEC_OPTION)
certificate_breakglass_validity_before_seconds = config.getint(
BLESS_OPTIONS_SECTION,
CERTIFICATE_BREAKGLASS_BEFORE_SEC_OPTION
)
certificate_breakglass_validity_after_seconds = config.getint(
BLESS_OPTIONS_SECTION,
CERTIFICATE_BREAKGLASS_AFTER_SEC_OPTION
)
breakglass_user = config.get(BLESS_OPTIONS_SECTION, BREAKGLASS_USER_OPTION)
entropy_minimum_bits = config.getint(BLESS_OPTIONS_SECTION, ENTROPY_MINIMUM_BITS_OPTION)
random_seed_bytes = config.getint(BLESS_OPTIONS_SECTION, RANDOM_SEED_BYTES_OPTION)
ca_private_key_file = config.get(BLESS_CA_SECTION, CA_PRIVATE_KEY_FILE_OPTION)
password_ciphertext_b64 = config.getpassword()
certificate_extensions = config.get(BLESS_OPTIONS_SECTION, CERTIFICATE_EXTENSIONS_OPTION)
encrypted_okta_api_token = config.get(OKTA_OPTIONS_SECTION, ENCRYPTED_OKTA_API_TOKEN_OPTION)
okta_base_url = config.get(OKTA_OPTIONS_SECTION, OKTA_BASE_URL_OPTION)
okta_allowed_groups = config.get(OKTA_OPTIONS_SECTION, OKTA_ALLOWED_GROUPS_OPTION)
if okta_allowed_groups:
okta_allowed_groups = set(okta_allowed_groups.split(','))
logger.debug("Allowed okta groups: {}".format(okta_allowed_groups))
# Process cert request
schema = BlessSchema(strict=True)
try:
request = schema.load(event).data
except ValidationError as e:
return error_response('InputValidationError', str(e))
logger.info('Bless lambda invoked by okta user: {}@{}, bastion user: {}, kmsauth_token: {}]'.format(
request.okta_user,
request.bastion_user_ip,
request.bastion_user,
request.kmsauth_token)
)
# read the private key .pem
with open(os.path.join(os.path.dirname(__file__), ca_private_key_file), 'r') as f:
ca_private_key = f.read()
kms_client = boto3.client('kms', region_name=region)
# decrypt ca private key password
if ca_private_key_password is None:
try:
ca_password = kms_client.decrypt(
CiphertextBlob=base64.b64decode(password_ciphertext_b64))
ca_private_key_password = ca_password['Plaintext']
except ClientError as e:
return error_response('ClientError', str(e))
# decrypt okta api token
if okta_api_token is None:
try:
decrypted_okta_api_token = kms_client.decrypt(
CiphertextBlob=base64.b64decode(encrypted_okta_api_token))
okta_api_token = decrypted_okta_api_token['Plaintext']
except ClientError as e:
return error_response('ClientError', str(e))
'''
Fetch user context from Okta
* Username
* Groups
* SSH key
'''
# add extra property to Okta user profile schema
OktaUserProfile.types['public_key'] = str
okta_users_client = okta.UsersClient(okta_base_url, okta_api_token)
user = okta_users_client.get_user(request.okta_user)
groups_info = okta_users_client.get_user_groups(request.okta_user)
groups = set()
for group_info in groups_info:
# Encode unicode response from okta json api as a byte string to ease comparisons
groups.add(group_info.profile.name.encode('utf-8'))
logger.debug('User groups: {}'.format(groups))
allowed_groups = okta_allowed_groups
logger.debug('Whitelist groups: {}'.format(allowed_groups))
logger.debug('Matched groups: {}'.format(groups.intersection(allowed_groups)))
# If the len is greater than 0, breakglass will be false.
breakglass = not len(groups.intersection(allowed_groups))
public_key_to_sign = user.profile.public_key
if public_key_to_sign.startswith(VALID_SSH_RSA_PUBLIC_KEY_HEADER):
pass
else:
raise ValidationError('Invalid SSH Public Key.')
# if running as a Lambda, we can check the entropy pool and seed it with KMS if desired
if entropy_check:
with open('/proc/sys/kernel/random/entropy_avail', 'r') as f:
entropy = int(f.read())
logger.debug(entropy)
if entropy < entropy_minimum_bits:
logger.info(
'System entropy was {}, which is lower than the entropy_'
'minimum {}. Using KMS to seed /dev/urandom'.format(
entropy, entropy_minimum_bits))
response = kms_client.generate_random(
NumberOfBytes=random_seed_bytes)
random_seed = response['Plaintext']
with open('/dev/urandom', 'w') as urandom:
urandom.write(random_seed)
# cert values determined only by lambda and its configs
current_time = int(time.time())
test_user = config.get(BLESS_OPTIONS_SECTION, TEST_USER_OPTION)
if test_user and (request.bastion_user == test_user or request.remote_usernames == test_user):
# This is a test call, the lambda will issue an invalid
# certificate where valid_before < valid_after
valid_before = current_time
valid_after = current_time + 1
bypass_time_validity_check = True
else: # Normal user flow
bypass_time_validity_check = False
valid_before = current_time + certificate_validity_after_seconds
valid_after = current_time - certificate_validity_before_seconds
# Authenticate the user with KMS, if key is setup
if config.get(KMSAUTH_SECTION, KMSAUTH_USEKMSAUTH_OPTION):
if request.kmsauth_token:
try:
validator = KMSTokenValidator(
None,
config.getkmsauthkeyids(),
config.get(KMSAUTH_SECTION, KMSAUTH_SERVICE_ID_OPTION),
region
)
# decrypt_token will raise a TokenValidationError if token doesn't match
validator.decrypt_token(
"2/user/{}".format(request.remote_usernames.split(',')[0]),
request.kmsauth_token
)
except TokenValidationError as e:
return error_response('KMSAuthValidationError', str(e))
else:
return error_response('InputValidationError', 'Invalid request, missing kmsauth token')
# Build the cert
ca = get_ssh_certificate_authority(ca_private_key, ca_private_key_password)
cert_builder = get_ssh_certificate_builder(ca, SSHCertificateType.USER,
public_key_to_sign)
# Handle breakglass certificate modifications
if breakglass:
logger.critical('Breakglass access for okta user: {}@{}, bastion user: {}'.format(
request.okta_user,
request.bastion_user_ip,
request.bastion_user)
)
valid_before = current_time + certificate_breakglass_validity_before_seconds
valid_after = current_time - certificate_breakglass_validity_after_seconds
cert_builder.add_valid_principal(breakglass_user)
for username in request.remote_usernames.split(','):
cert_builder.add_valid_principal(username)
cert_builder.set_valid_before(valid_before)
cert_builder.set_valid_after(valid_after)
if certificate_extensions:
for e in certificate_extensions.split(','):
if e:
cert_builder.add_extension(e)
else:
cert_builder.clear_extensions()
# cert_builder is needed to obtain the SSH public key's fingerprint
key_id = 'AWS Request ID: {}, User: {}, Source IP: {}, Command: {}, ' \
'Fingerprint: {}, Bless CA: {}, Expires: {}'\
.format(
context.aws_request_id,
request.bastion_user,
request.bastion_user_ip,
request.command,
cert_builder.ssh_public_key.fingerprint,
context.invoked_function_arn,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_before))
)
cert_builder.set_critical_option_source_addresses(request.bastion_ips)
cert_builder.set_key_id(key_id)
cert = cert_builder.get_cert_file(bypass_time_validity_check)
logger.info(
'Issued a cert to bastion_ips[{}] for the remote_usernames of [{}] with the key_id[{}] and '
'valid_from[{}])'.format(
request.bastion_ips, request.remote_usernames, key_id,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_after))))
return success_response(cert)
def lambda_handler(event, context=None, ca_private_key_password=None,
entropy_check=True,
config_file=os.path.join(os.path.dirname(__file__), 'bless_deploy.cfg')):
"""
This is the function that will be called when the lambda function starts.
:param event: Dictionary of the json request.
:param context: AWS LambdaContext Object
http://docs.aws.amazon.com/lambda/latest/dg/python-context-object.html
:param ca_private_key_password: For local testing, if the password is provided, skip the KMS
decrypt.
:param entropy_check: For local testing, if set to false, it will skip checking entropy and
won't try to fetch additional random from KMS
:param config_file: The config file to load the SSH CA private key from, and additional settings
:return: the SSH Certificate that can be written to id_rsa-cert.pub or similar file.
"""
# AWS Region determines configs related to KMS
region = os.environ['AWS_REGION']
# Load the deployment config values
config = BlessConfig(region,
config_file=config_file)
logging_level = config.get(BLESS_OPTIONS_SECTION, LOGGING_LEVEL_OPTION)
numeric_level = getattr(logging, logging_level.upper(), None)
if not isinstance(numeric_level, int):
raise ValueError('Invalid log level: {}'.format(logging_level))
logger = logging.getLogger()
logger.setLevel(numeric_level)
certificate_validity_window_seconds = config.getint(BLESS_OPTIONS_SECTION,
CERTIFICATE_VALIDITY_WINDOW_SEC_OPTION)
entropy_minimum_bits = config.getint(BLESS_OPTIONS_SECTION, ENTROPY_MINIMUM_BITS_OPTION)
random_seed_bytes = config.getint(BLESS_OPTIONS_SECTION, RANDOM_SEED_BYTES_OPTION)
ca_private_key_file = config.get(BLESS_CA_SECTION, CA_PRIVATE_KEY_FILE_OPTION)
password_ciphertext_b64 = config.getpassword()
# read the private key .pem
with open(os.path.join(os.path.dirname(__file__), ca_private_key_file), 'r') as f:
ca_private_key = f.read()
# decrypt ca private key password
if ca_private_key_password is None:
kms_client = boto3.client('kms', region_name=region)
ca_password = kms_client.decrypt(
CiphertextBlob=base64.b64decode(password_ciphertext_b64))
ca_private_key_password = ca_password['Plaintext']
# if running as a Lambda, we can check the entropy pool and seed it with KMS if desired
if entropy_check:
with open('/proc/sys/kernel/random/entropy_avail', 'r') as f:
entropy = int(f.read())
logger.debug(entropy)
if entropy < entropy_minimum_bits:
logger.info(
'System entropy was {}, which is lower than the entropy_'
'minimum {}. Using KMS to seed /dev/urandom'.format(
entropy, entropy_minimum_bits))
response = kms_client.generate_random(
NumberOfBytes=random_seed_bytes)
random_seed = response['Plaintext']
with open('/dev/urandom', 'w') as urandom:
urandom.write(random_seed)
# Process cert request
schema = BlessSchema(strict=True)
request = schema.load(event).data
# cert values determined only by lambda and its configs
current_time = int(time.time())
valid_before = current_time + certificate_validity_window_seconds
valid_after = current_time - certificate_validity_window_seconds
# Build the cert
ca = get_ssh_certificate_authority(ca_private_key, ca_private_key_password)
cert_builder = get_ssh_certificate_builder(ca, SSHCertificateType.USER,
request.public_key_to_sign)
cert_builder.add_valid_principal(request.remote_username)
cert_builder.set_valid_before(valid_before)
cert_builder.set_valid_after(valid_after)
# cert_builder is needed to obtain the ssh public key's fingerprint
key_id = 'request[{}] for[{}] from[{}] command[{}] ssh_key:[{}] ca:[{}] valid_to[{}]'.format(
context.aws_request_id, request.bastion_user, request.bastion_user_ip, request.command,
cert_builder.ssh_public_key.fingerprint, context.invoked_function_arn,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_before)))
cert_builder.set_critical_option_source_address(request.bastion_ip)
cert_builder.set_key_id(key_id)
cert = cert_builder.get_cert_file()
logger.info(
'Issued a cert to bastion_ip[{}] for the remote_username of [{}] with the key_id[{}] and '
'valid_from[{}])'.format(
request.bastion_ip, request.remote_username, key_id,
time.strftime("%Y/%m/%d %H:%M:%S", time.gmtime(valid_after))))
return cert