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Replace HMAC-based session API keys with tokens stored in memory in the daemon process

Since the session cache clears keys after a period of time, this fixes #1821.

Based on https://github.com/mail-in-a-box/mailinabox/pull/2012, and so:

Co-Authored-By: NewbieOrange <NewbieOrange@users.noreply.github.com>

Also fixes #2029 by not revealing through the login failure error message whether a user exists or not.
pull/2033/head
Joshua Tauberer 5 months ago
parent
commit
e884c4774f
  1. 34
      api/mailinabox.yml
  2. 179
      management/auth.py
  3. 29
      management/daemon.py
  4. 6
      management/templates/index.html
  5. 4
      management/templates/login.html
  6. 4
      setup/management.sh
  7. 2
      tests/fail2ban.py

34
api/mailinabox.yml

@ -54,24 +54,24 @@ tags:
System operations, which include system status checks, new version checks
and reboot status.
paths:
/me:
get:
/login:
post:
tags:
- User
summary: Get user information
summary: Exchange a username and password for a session API key.
description: |
Returns user information. Used for user authentication.
Returns user information and a session API key.
Authenticate a user by supplying the auth token as a base64 encoded string in
format `email:password` using basic authentication headers.
If successful, a long-lived `api_key` is returned which can be used for subsequent
requests to the API.
operationId: getMe
requests to the API in place of the password.
operationId: login
x-codeSamples:
- lang: curl
source: |
curl -X GET "https://{host}/admin/me" \
curl -X GET "https://{host}/admin/login" \
-u "<email>:<password>"
responses:
200:
@ -92,6 +92,24 @@ paths:
privileges:
- admin
status: ok
/logout:
post:
tags:
- User
summary: Invalidates a session API key.
description: |
Invalidates a session API key so that it cannot be used after this API call.
operationId: logout
x-codeSamples:
- lang: curl
source: |
curl -X GET "https://{host}/admin/logout" \
-u "<email>:<session_key>"
responses:
200:
description: Successful operation
content:
application/json:
/system/status:
post:
tags:
@ -1803,7 +1821,7 @@ components:
The `access-token` is comprised of the Base64 encoding of `username:password`.
The `username` is the mail user's email address, and `password` can either be the mail user's
password, or the `api_key` returned from the `getMe` operation.
password, or the `api_key` returned from the `login` operation.
When using `curl`, you can supply user credentials using the `-u` or `--user` parameter.
requestBodies:

179
management/auth.py

@ -1,5 +1,7 @@
import base64, os, os.path, hmac, json, secrets
from datetime import timedelta
from expiringdict import ExpiringDict
import utils
from mailconfig import get_mail_password, get_mail_user_privileges
@ -9,16 +11,13 @@ DEFAULT_KEY_PATH = '/var/lib/mailinabox/api.key'
DEFAULT_AUTH_REALM = 'Mail-in-a-Box Management Server'
class AuthService:
"""Generate an API key for authenticating clients
Clients must read the key from the key file and send the key with all HTTP
requests. The key is passed as the username field in the standard HTTP
Basic Auth header.
"""
def __init__(self):
self.auth_realm = DEFAULT_AUTH_REALM
self.key_path = DEFAULT_KEY_PATH
self.max_session_duration = timedelta(days=2)
self.init_system_api_key()
self.sessions = ExpiringDict(max_len=64, max_age_seconds=self.max_session_duration.total_seconds())
def init_system_api_key(self):
"""Write an API key to a local file so local processes can use the API"""
@ -31,123 +30,133 @@ class AuthService:
finally:
os.umask(old_umask)
self.key = secrets.token_hex(24)
self.key = secrets.token_hex(32)
os.makedirs(os.path.dirname(self.key_path), exist_ok=True)
with create_file_with_mode(self.key_path, 0o640) as key_file:
key_file.write(self.key + '\n')
def authenticate(self, request, env):
"""Test if the client key passed in HTTP Authorization header matches the service key
or if the or username/password passed in the header matches an administrator user.
def authenticate(self, request, env, login_only=False, logout=False):
"""Test if the HTTP Authorization header's username matches the system key, a session key,
or if the username/password passed in the header matches a local user.
Returns a tuple of the user's email address and list of user privileges (e.g.
('my@email', []) or ('my@email', ['admin']); raises a ValueError on login failure.
If the user used an API key, the user's email is returned as None."""
def decode(s):
return base64.b64decode(s.encode('ascii')).decode('ascii')
If the user used the system API key, the user's email is returned as None since
this key is not associated with a user."""
def parse_basic_auth(header):
def parse_http_authorization_basic(header):
def decode(s):
return base64.b64decode(s.encode('ascii')).decode('ascii')
if " " not in header:
return None, None
scheme, credentials = header.split(maxsplit=1)
if scheme != 'Basic':
return None, None
credentials = decode(credentials)
if ":" not in credentials:
return None, None
username, password = credentials.split(':', maxsplit=1)
return username, password
header = request.headers.get('Authorization')
if not header:
raise ValueError("No authorization header provided.")
username, password = parse_basic_auth(header)
username, password = parse_http_authorization_basic(request.headers.get('Authorization', ''))
if username in (None, ""):
raise ValueError("Authorization header invalid.")
if username == self.key:
# The user passed the system API key which grants administrative privs.
if username.strip() == "" and password.strip() == "":
raise ValueError("No email address, password, session key, or API key provided.")
# If user passed the system API key, grant administrative privs. This key
# is not associated with a user.
if username == self.key and not login_only:
return (None, ["admin"])
else:
# The user is trying to log in with a username and either a password
# (and possibly a MFA token) or a user-specific API key.
return (username, self.check_user_auth(username, password, request, env))
def check_user_auth(self, email, pw, request, env):
# Validate a user's login email address and password. If MFA is enabled,
# check the MFA token in the X-Auth-Token header.
#
# On success returns a list of privileges (e.g. [] or ['admin']). On login
# failure, raises a ValueError with a login error message.
# Sanity check.
if email == "" or pw == "":
raise ValueError("Enter an email address and password.")
# The password might be a user-specific API key. create_user_key raises
# a ValueError if the user does not exist.
if hmac.compare_digest(self.create_user_key(email, env), pw):
# OK.
pass
else:
# Get the hashed password of the user. Raise a ValueError if the
# email address does not correspond to a user.
pw_hash = get_mail_password(email, env)
# If the password corresponds with a session token for the user, grant access for that user.
if password in self.sessions and self.sessions[password]["email"] == username and not login_only:
sessionid = password
session = self.sessions[sessionid]
if session["password_token"] != self.create_user_password_state_token(username, env):
# This session is invalid because the user's password/MFA state changed
# after the session was created.
del self.sessions[sessionid]
raise ValueError("Session expired.")
if logout:
# Clear the session.
del self.sessions[sessionid]
else:
# Re-up the session so that it does not expire.
self.sessions[sessionid] = session
# If no password was given, but a username was given, we're missing some information.
elif password.strip() == "":
raise ValueError("Enter a password.")
# Authenticate.
try:
# Use 'doveadm pw' to check credentials. doveadm will return
# a non-zero exit status if the credentials are no good,
# and check_call will raise an exception in that case.
utils.shell('check_call', [
"/usr/bin/doveadm", "pw",
"-p", pw,
"-t", pw_hash,
])
except:
# Login failed.
raise ValueError("Invalid password.")
# If MFA is enabled, check that MFA passes.
status, hints = validate_auth_mfa(email, request, env)
if not status:
# Login valid. Hints may have more info.
raise ValueError(",".join(hints))
else:
# The user is trying to log in with a username and a password
# (and possibly a MFA token). On failure, an exception is raised.
self.check_user_auth(username, password, request, env)
# Get privileges for authorization. This call should never fail because by this
# point we know the email address is a valid user. But on error the call will
# return a tuple of an error message and an HTTP status code.
privs = get_mail_user_privileges(email, env)
# point we know the email address is a valid user --- unless the user has been
# deleted after the session was granted. On error the call will return a tuple
# of an error message and an HTTP status code.
privs = get_mail_user_privileges(username, env)
if isinstance(privs, tuple): raise ValueError(privs[0])
# Return a list of privileges.
return privs
# Return the authorization information.
return (username, privs)
def create_user_key(self, email, env):
# Create a user API key, which is a shared secret that we can re-generate from
# static information in our database. The shared secret contains the user's
# email address, current hashed password, and current MFA state, so that the
# key becomes invalid if any of that information changes.
#
# Use an HMAC to generate the API key using our system API key as a key,
# which also means that the API key becomes invalid when our system API key
# changes --- i.e. when this process is restarted.
def check_user_auth(self, email, pw, request, env):
# Validate a user's login email address and password. If MFA is enabled,
# check the MFA token in the X-Auth-Token header.
#
# Raises ValueError via get_mail_password if the user doesn't exist.
# On login failure, raises a ValueError with a login error message. On
# success, nothing is returned.
# Authenticate.
try:
# Get the hashed password of the user. Raise a ValueError if the
# email address does not correspond to a user. But wrap it in the
# same exception as if a password fails so we don't easily reveal
# if an email address is valid.
pw_hash = get_mail_password(email, env)
# Construct the HMAC message from the user's email address and current password.
msg = b"AUTH:" + email.encode("utf8") + b" " + get_mail_password(email, env).encode("utf8")
# Use 'doveadm pw' to check credentials. doveadm will return
# a non-zero exit status if the credentials are no good,
# and check_call will raise an exception in that case.
utils.shell('check_call', [
"/usr/bin/doveadm", "pw",
"-p", pw,
"-t", pw_hash,
])
except:
# Login failed.
raise ValueError("Incorrect email address or password.")
# If MFA is enabled, check that MFA passes.
status, hints = validate_auth_mfa(email, request, env)
if not status:
# Login valid. Hints may have more info.
raise ValueError(",".join(hints))
def create_user_password_state_token(self, email, env):
# Create a token that changes if the user's password or MFA options change
# so that sessions become invalid if any of that information changes.
msg = get_mail_password(email, env).encode("utf8")
# Add to the message the current MFA state, which is a list of MFA information.
# Turn it into a string stably.
msg += b" " + json.dumps(get_hash_mfa_state(email, env), sort_keys=True).encode("utf8")
# Make the HMAC.
# Make a HMAC using the system API key as a hash key.
hash_key = self.key.encode('ascii')
return hmac.new(hash_key, msg, digestmod="sha256").hexdigest()
def create_session_key(self, username, env, type=None):
# Create a new session.
token = secrets.token_hex(32)
self.sessions[token] = {
"email": username,
"password_token": self.create_user_password_state_token(username, env),
}
return token

29
management/daemon.py

@ -56,8 +56,10 @@ def authorized_personnel_only(viewfunc):
try:
email, privs = auth_service.authenticate(request, env)
except ValueError as e:
# Write a line in the log recording the failed login
log_failed_login(request)
# Write a line in the log recording the failed login, unless no authorization header
# was given which can happen on an initial request before a 403 response.
if "Authorization" in request.headers:
log_failed_login(request)
# Authentication failed.
error = str(e)
@ -134,11 +136,12 @@ def index():
csr_country_codes=csr_country_codes,
)
@app.route('/me')
def me():
# Create a session key by checking the username/password in the Authorization header.
@app.route('/login', methods=["POST"])
def login():
# Is the caller authorized?
try:
email, privs = auth_service.authenticate(request, env)
email, privs = auth_service.authenticate(request, env, login_only=True)
except ValueError as e:
if "missing-totp-token" in str(e):
return json_response({
@ -153,19 +156,29 @@ def me():
"reason": str(e),
})
# Return a new session for the user.
resp = {
"status": "ok",
"email": email,
"privileges": privs,
"api_key": auth_service.create_session_key(email, env, type='login'),
}
# Is authorized as admin? Return an API key for future use.
if "admin" in privs:
resp["api_key"] = auth_service.create_user_key(email, env)
app.logger.info("New login session created for {}".format(email))
# Return.
return json_response(resp)
@app.route('/logout', methods=["POST"])
def logout():
try:
email, _ = auth_service.authenticate(request, env, logout=True)
app.logger.info("{} logged out".format(email))
except ValueError as e:
pass
finally:
return json_response({ "status": "ok" })
# MAIL
@app.route('/mail/users')

6
management/templates/index.html

@ -367,11 +367,17 @@ var current_panel = null;
var switch_back_to_panel = null;
function do_logout() {
// Clear the session from the backend.
api("/logout", "POST");
// Forget the token.
api_credentials = ["", ""];
if (typeof localStorage != 'undefined')
localStorage.removeItem("miab-cp-credentials");
if (typeof sessionStorage != 'undefined')
sessionStorage.removeItem("miab-cp-credentials");
// Return to the start.
show_panel('login');
}

4
management/templates/login.html

@ -105,8 +105,8 @@ function do_login() {
api_credentials = [$('#loginEmail').val(), $('#loginPassword').val()]
api(
"/me",
"GET",
"/login",
"POST",
{},
function(response) {
// This API call always succeeds. It returns a JSON object indicating

4
setup/management.sh

@ -49,8 +49,8 @@ hide_output $venv/bin/pip install --upgrade pip
# NOTE: email_validator is repeated in setup/questions.sh, so please keep the versions synced.
hide_output $venv/bin/pip install --upgrade \
rtyaml "email_validator>=1.0.0" "exclusiveprocess" \
flask dnspython python-dateutil \
qrcode[pil] pyotp \
flask dnspython python-dateutil expiringdict \
qrcode[pil] pyotp \
"idna>=2.0.0" "cryptography==2.2.2" boto psutil postfix-mta-sts-resolver b2sdk
# CONFIGURATION

2
tests/fail2ban.py

@ -232,7 +232,7 @@ if __name__ == "__main__":
run_test(managesieve_test, [], 20, 30, 4)
# Mail-in-a-Box control panel
run_test(http_test, ["/admin/me", 200], 20, 30, 1)
run_test(http_test, ["/admin/login", 200], 20, 30, 1)
# Munin via the Mail-in-a-Box control panel
run_test(http_test, ["/admin/munin/", 401], 20, 30, 1)

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