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https://issues.apache.org/jira/browse/HADOOP-12468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14971117#comment-14971117
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Wei-Chiu Chuang commented on HADOOP-12468:
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To [~yzhangal], to address your comment #1,
(1) I can not make an end-to-end test case, because the group resolution is the
output from shell command 'id'. To reproduce the scenario where the group id
does not resolve, I must manually tweak /etc/group to make it happen.
(2) Fortunately, by tweaking /etc/group, I was able to reproduce the scenario,
such that part of "id -Gn" output is numerical group id. In addition, the test
case emulates the output from the shell command. By piecing together the two
parts, I can verify the fix is valid.
> Partial group resolution failure should not result in user lockout
> ------------------------------------------------------------------
>
> Key: HADOOP-12468
> URL: https://issues.apache.org/jira/browse/HADOOP-12468
> Project: Hadoop Common
> Issue Type: Bug
> Components: security
> Affects Versions: 2.6.1
> Environment: Linux
> Reporter: Wei-Chiu Chuang
> Assignee: Wei-Chiu Chuang
> Priority: Minor
> Attachments: HADOOP-12468.001.patch, HADOOP-12468.002.patch,
> HADOOP-12468.003.patch
>
>
> If a Hadoop cluster is configured to use ShellBasedUnixGroupsMapping for
> user/group name mapping, occasionally some group names may become
> unresolvable (for example, using SSSD).
> ShellBasedUnixGroupsMapping uses shell command "id -Gn" to retrieve the group
> name of a user; however, the existing logic assumes that if the exit code of
> the command is non-zero, the user has no group name at all. The shell command
> in Linux returns non-zero exit code if a group name is not resolvable.
> Unfortunately, it is possible that a user belongs to multiple groups, and any
> partial failure in group name resolution would denied the user's access.
> On the other hand, the JNI implementation (JniBasedUnixGroupsMapping) is more
> resilient. If any group name is unresolvable, it is simply ignored, and
> whatever are resolvable are returned.
> It is arguable that if the group name is not resolvable, the administrator
> should configure their directory/authentication service correctly, and Hadoop
> is in no position to handle it, but since the existing unit tests assume the
> output of JNI-based and shell-based implementation are the same, we should
> improve the shell-based group name resolution, and make it as resilient as
> the JNI-based one.
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