Repository: incubator-impala Updated Branches: refs/heads/master db60c1cd2 -> e71e359af
KUDU-2087. Fix failure to map Kerberos principal to username with FreeIPA FreeIPA is a piece of software that automates and simplifies management of MIT krb5, SSSD, some LDAP service, etc. FreeIPA configures a localauth plugin[1] in krb5.conf to map Kerberos principals to local usernames. In this configuration, Kudu daemons were failing to start up due to failure to map their own service principals back to a username. This is due to a number of issues: 1) FreeIPA distinguishes between service principals and user principals and doesn't store a 'uid' field in LDAP for service principals. Thus, when 'sssd' tries to map a service principal to a local unix user, it determines that there is no such user (ie getpwnam() fails). This is by design, best I can tell. 2) sssd's implementation of krb5_auth_to_localname[1] uses getpwnam to try to map the kerberos principal to the local username. Because of the above, it fails for service principals. 3) Prior to el7.3, ssd configures krb5 with 'enable_only = sssd' in the localauth plugin section. This means that if sssd fails to perform the mapping, it does not fall back to other mappings defined in krb5.conf (eg explicitly defined auth_to_local rules). See [2] 4) Even after 7.3, there is an additional bug in sssd which I just filed[3], which causes the fallback to still not work. Because of this, we're getting the KRB5_PLUGIN_NO_HANDLE error code back up at the Kudu layer. We already have our own fallback case for KRB5_LNAME_NO_TRANS, and it seems like we should just be handling PLUGIN_NO_HANDLE in the same way to workaround the above behavior. I tested this patch on a FreeIPA-configured system on el6.7. I was able to successfully start a master with a FreeIPA-provided keytab and authentication required, and use 'kudu table list' to authenticate to it. [1] https://github.com/SSSD/sssd/blob/master/src/krb5_plugin/sssd_krb5_localauth_plugin.c [2] https://bugzilla.redhat.com/show_bug.cgi?id=1297462 [3] https://pagure.io/SSSD/sssd/issue/3459 Change-Id: I7bc13b33053a73784350c9d30a3796a96d318c04 Reviewed-on: http://gerrit.cloudera.org:8080/7551 Tested-by: Kudu Jenkins Reviewed-by: Alexey Serbin <[email protected]> Reviewed-on: http://gerrit.cloudera.org:8080/7745 Reviewed-by: Michael Ho <[email protected]> Tested-by: Impala Public Jenkins Project: http://git-wip-us.apache.org/repos/asf/incubator-impala/repo Commit: http://git-wip-us.apache.org/repos/asf/incubator-impala/commit/2f3e824a Tree: http://git-wip-us.apache.org/repos/asf/incubator-impala/tree/2f3e824a Diff: http://git-wip-us.apache.org/repos/asf/incubator-impala/diff/2f3e824a Branch: refs/heads/master Commit: 2f3e824af6b80becb4feeba23138ccfbe6c0602d Parents: db60c1c Author: Todd Lipcon <[email protected]> Authored: Mon Jul 31 18:58:26 2017 -0700 Committer: Impala Public Jenkins <[email protected]> Committed: Tue Aug 22 21:35:24 2017 +0000 ---------------------------------------------------------------------- be/src/kudu/security/init.cc | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/incubator-impala/blob/2f3e824a/be/src/kudu/security/init.cc ---------------------------------------------------------------------- diff --git a/be/src/kudu/security/init.cc b/be/src/kudu/security/init.cc index c9baeb4..dfbb25c 100644 --- a/be/src/kudu/security/init.cc +++ b/be/src/kudu/security/init.cc @@ -436,9 +436,13 @@ Status MapPrincipalToLocalName(const std::string& principal, std::string* local_ // first component of the principal. rc = KRB5_LNAME_NOTRANS; #endif - if (rc == KRB5_LNAME_NOTRANS) { + if (rc == KRB5_LNAME_NOTRANS || rc == KRB5_PLUGIN_NO_HANDLE) { // No name mapping specified. We fall back to simply taking the first component // of the principal, for compatibility with the default behavior of Hadoop. + // + // NOTE: KRB5_PLUGIN_NO_HANDLE isn't typically expected here, but works around + // a bug in SSSD's auth_to_local implementation: https://pagure.io/SSSD/sssd/issue/3459 + // // TODO(todd): we should support custom configured auth-to-local mapping, since // most Hadoop ecosystem components do not load them from krb5.conf. if (princ->length > 0) {
