|Hello Jamers! As part of our work at Linagora, we are looking toward -
better integrating James within our product suite and for us this means
support "Single Sign On" and "Single Log Out" for JMAP following the
OpenId connect standard [0]. - Improving security standards used to
operate James. (We have a growing activity within the health care
market, sensible to security arguments) Regarding security standards we
should ideally: - Be able to NOT advertise AUTH / LOGIN capabilities of
unencrypted channels (Correspond to IMAP plainAuthDissallowed but
generalized to other protocols) - Be able to require OAUTH/OIDC
authentication for all protocols (IMAP, SMTP, JMAP) - this is what some
of the health care providers we spoke to desired to do. - For our
collaborative suite usage, while OIDC only for JMAP makes sense, we
still wish to maintain PLAIN AUTH for IMAP and SMTP. - Of course
settings for regular users not interested in OIDC should not change (no
breaking changes, OIDC adoption is opt-in only). As such we propose
ourselves to: - Contribute IMAP and SMTP SASL OAUTH extension described
in [RFC-7628] - Modularize JMAP authentication mechanisms (letting the
admin choose which one she wishes to use) - Enable authentication
through a header mechanism eg `X-USER: btell...@apache.org`, which can
be used to delegate OIDC authentication through a third party API
gateway. We have Krackend [1] in mind. - Share documentation and a
docker-compose of OIDC setup for IMAP, SMTP and JMAP in
https://github.com/apache/james-project/tree/master/examples/oidc. This
would include: - A LDAP still used by James UsersRepository. Provisioned
with a testing user. - A pre-configured Keycloack [2] OpenID connect
provider. - A pre-configured Krakend API gateway proxying JMAP - And
finally a James server configured to only accept OIDC as an
authentication mechanism for IMAP, SMTP and JMAP. - Unit tests for
existing IMAP `plainAuthDissallowed` configuration parameter. Finally
this is a good opportunity to restructure authentication related
settings in imapserver.xml and smtpserver.xml file. Here are proposals
for both files: [imapserver.xml] ---- <imapserver enabled="true">
<jmxName>imapserver-ssl</jmxName> <bind>0.0.0.0:993</bind> <tls
socketTLS="true" startTLS="false">
<privateKey>file://conf/private.key</privateKey>
<certificates>file://conf/certs.self-signed.csr</certificates> </tls>
<!-- ... --> <authentication>
<plainAuthEnabled>true|false</plainAuthEnabled> <!-- defaults to true
--> <oauth> <!-- ommiting this block would disable oauth. All fields are
compulsory --> <publicKey>file://conf/imapJWT.pub</publicKey>
<oidcConfigurationURL>https://example.com/.well-known/openid-config</oidcConfigurationURL>
<claim>mailAddress</claim> </oauth> </authentication> </imapserver> ----
[smtpserver.xml] ---- <smtpserver enabled="true">
<jmxName>smtpserver-ssl</jmxName> <bind>0.0.0.0:465</bind> <tls
socketTLS="true" startTLS="false">
<privateKey>file://conf/private.key</privateKey>
<certificates>file://conf/certs.self-signed.csr</certificates> </tls>
<!--- ... --> <requireAuthForRelay>true|false</requireAuthForRelay>
<authentication> <plainAuthEnabled>true|false</plainAuthEnabled> <!--
defaults to true --> <oauth> <!-- ommiting this block would disable
oauth. All fields are compulsory -->
<publicKey>file://conf/imapJWT.pub</publicKey>
<oidcConfigurationURL>https://example.com/.well-known/openid-config</oidcConfigurationURL>
<claim>mailAddress</claim> </oauth> </authentication> </smtpserver> ----
You can see that: - The `plainAuthDissallowed` parameter is proposed to
be renamed to `auth.requireSSL`. (of course we should support fallback
NOT to have a breaking change) - `auth.plainAuthEnabled` enable turning
on/off plain auth, which allows having OIDC only mechanism. -
`auth.requireSSL` will be generalized to SMTP. - In SMTP `requireAuth`
setting is very misleading as it rather is `requireAuthForRelay`. I
propose we rename this configuration option (of course we should support
fallback NOT to have a breaking change). Here is the implementation
strategies we would follow: - For JMAP have Krakend doing all the hard
job for us, and use a dedicated header to carry the information over to
James. - Our code contributions aims at easing such a setup (that would
only require configuration) - Provide an informative example using
krakend. We understand that this choice is ours, yet sharing it could
allow reuse or similar setup - If some people wishes to write an OIDC
authentication strategy directly in James then they perfectly can!
(Reusing the modularization of JMAP authentication strategies we would
provide). - For IMAP and SMTP then we proposes to check the bearer
payload against a statically configured public key for these protocols.
(Sadly there is no API gateway for those protocols) - Drawbacks includes
no revocation of access tokens (once it's signed it is always valid),
revocation do not shut down existing connections authenticated with the
revocated token, and key rotation would require reconfiguration and
reboot. - One alternative would be to systematically ask the OpenID
server to validate the bearer. This might be acceptable as IMAP and SMTP
are long lived protocols that do not often establish new connections.
While this do not change anything regarding already opened connection
management, this solves revocation and public key rotation at the price
of exposing more the identity provider... - Of course James could expose
a back-channel for token invalidation, stored in some kind of shared
storage, but this complexify things a bit. - Similarily HTTP calls could
be made to get the JWKS key (and cache it) but this also complexify the
picture quite a bit... I am deeply convinced this efforts would help
James admins more control over exposed authentication mechanisms and
ultimately offer state of the art authentication options. This should
help James check a few more boxes in security reviews and eventually
ease adoption! Useful links: [0] OpenId spec:
https://openid.net/specs/openid-connect-core-1_0.html [1] Krakend:
https://www.krakend.io/ [2] Keycloack: https://www.keycloak.org/
[RFC-7628] SASL OATH mechanism for SMTP and IMAP:
https://datatracker.ietf.org/doc/html/rfc7628 Krakend configured with
keycloack: https://www.krakend.io/docs/authorization/keycloak/ Krakend
configured with token revocation:
https://www.krakend.io/docs/authorization/revoking-tokens/ Best regards,
Benoit TELLIER|
