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https://issues.apache.org/jira/browse/HADOOP-12468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14975933#comment-14975933
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Harsh J commented on HADOOP-12468:
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The stderr seems worthy to parse to spot the bad groups specifically and ignore
them (vs. ignoring all numeric groups, which may result in a regression in some
user clusters).
Alternatively, the command {{id -G}} (no {{-n}}) returns numeric IDs. We could
match its results against {{id -Gn}} output to filter out unknown groups. The
assumption here is that the ordering will be the same.
> 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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