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Wei-Chiu Chuang commented on HADOOP-12468: ------------------------------------------ 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. -- This message was sent by Atlassian JIRA (v6.3.4#6332)