** Merge proposal linked: https://code.launchpad.net/~lvoytek/ubuntu/+source/cyrus-sasl2/+git/cyrus-sasl2/+merge/430580
-- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to openldap in Ubuntu. https://bugs.launchpad.net/bugs/1912256 Title: Missing channel binding prevents authentication to ActiveDirectory Status in cyrus-sasl2 package in Ubuntu: Fix Released Status in openldap package in Ubuntu: Fix Released Status in cyrus-sasl2 source package in Jammy: In Progress Status in openldap source package in Jammy: Fix Released Bug description: [Impact] When attempting to bind to a SASL channel using GSSAPI or GSS-SPNEGO for Windows Active Directory, authentication will fail stating invalid credentials as the cause. This is due to cyrus-sasl2 missing the feature of GSSAPI/GSS-SPNEGO channel binding and interoperability with Windows over TLS. To fix the issue, these items are added as patches from a set of upstream commits. [Test Plan] To reproduce this issue, a machine running Windows with Active Directory must be available over the network. As an example, for Windows Server 2019 Evaluation: The ISO can be downloaded from https://www.microsoft.com/en-us/evalcenter/download-windows-server-2019 Install Windows Server and Active Directory, then add the following registry changes from https://support.microsoft.com/en-us/topic/2020-ldap-channel-binding-and-ldap-signing-requirements-for-windows-kb4520412-ef185fb8-00f7-167d-744c-f299a66fc00a [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTDS\Parameters] "ldapserverintegrity"=dword:00000002 "LdapEnforceChannelBinding"=dword:00000002 Also enable LDAP logging for Active Directory: Reg Add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTDS\Diagnostics /v "16 LDAP Interface Events" /t REG_DWORD /d 2 With the Windows machine available, set up an Ubuntu system and do the following: Connect to the Windows machine's network Reboot and check if an IP from Windows Server was provided Install packages with: $ sudo apt install ldap-utils libsasl2-modules-gssapi-mit krb5-user When the Configuring Kerberos Authentication prompt shows up, use the realm of the Windows Server Save the Windows Server AD CA certificate file as /usr/local/share/ca-certificates/ad-ca.crt then run $ sudo update-ca-certificates In /etc/ldap/ldap.conf set BASE dc={REALM NAME} URI ldaps://{WINDOWS SERVER MACHINE NAME}.{REALM NAME} With Ubuntu set up, the actual test can be run: $ kinit Enter Password $ ldapwhoami -Y GSSAPI -O maxssf=0 -o SASL_CBINDING=tls-endpoint Prior to the fix, this would display the following: SASL/GSSAPI authentication started ldap_sasl_interactive_bind_s: Invalid credentials (49) additional info: 80090346: LdapErr: DSID-..., comment: AcceptSecurityContext error, data 80090346, v4563 With the fix, the authentication will display the user information. The same happens with $ ldapwhoami -Y GSS-SPNEGO -O maxssf=0 -o SASL_CBINDING=tls-endpoint SASL/GSS-SPNEGO authentication started ldap_sasl_interactive_bind_s: Invalid credentials (49) additional info: 80090346: LdapErr: DSID-..., comment: AcceptSecurityContext error, data 80090346, v4563 [Where problems could occur] Based on the patches added, any problems that show up would likely occour either in the gssapi plugin or the SASL2 macros. The two files changed are plugins/gssapi.c and m4/sasl2.m4, along with some tests. There are various situations apart from this one in which GSS-API can be used, and this change may affect the way some of these interactions over the network are handled. [Other Info] This issue was fixed in kinetic in version 2.1.28+dfsg-6ubuntu2 [Original Description] > Are you uncertain if your issue is really a bug? Effect is an authentication error. Root case is a "missing feature" (see below) and requires updating dependencies, downporting. > If you are certain this is a bug please include the source package the bug is in. It's in the interaction between three libraries: openldap, cyrus-sasl, krb5 > 1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu Broken in 18.04 and also in 20.10 (I guess it's also broken in anything inbetween) > 2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center libsasl2-modules-gssapi-mit: 2.1.27+dfsg-2ubuntu1 ldap-utils: 2.4.53+dfsg-1ubuntu1.2 libgssapi-krb5-2: 1.17-10ubuntu0.1 > 3) What you expected to happen # kinit $ export LDAPSASL_CBINDING=tls-endpoint $ ldapwhoami -O minssf=0,maxssf=0 -N -Y GSSAPI -H ldaps://<DC-fqdn> SASL/GSSAPI authentication started SASL username: <some-username> SASL SSF: 0 u:<some-username> > 4) What happened instead SASL/GSSAPI authentication started ldap_sasl_interactive_bind_s: Invalid credentials (49) additional info: 80090346: LdapErr: DSID-0C090597, comment: AcceptSecurityContext error, data 80090346, v4563 --------------- Microsoft ActiveDirectory has "LDAP Channel Binding" and recommends activating this as a required feature. See https://access.redhat.com/articles/4661861 Authentication to any AD DC which has mandatory channel binding fails. Channel binding requires at least an update to cyrus-sasl, which is not in any release as far as I can see: https://github.com/cyrusimap/cyrus- sasl/commit/975edbb69070eba6b035f08776de771a129cfb57 It also needs this commit in openldap: https://git.openldap.org/openldap/openldap/-/commit/3cd50fa8b32a21040a9892e2a8a7a9dfc7541ce6 Which as far as I can tell is v2.5 (branch OPENLDAP_REL_ENG_2_5). RH also mentions it needs up-to-date krb5 libraries, but I can't tell what minimum version this needs. I can build all libraries from source, current master (except for krb5 where I've used 1.18.3) and can confirm that channel binding works when using those libraries. I'm not sure if Samba is affected, but at least adcli, ldap-utils, and I would guess by extension also SSSD and realmd. 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