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Posted to common-issues@hadoop.apache.org by "Ahmed Hussein (Jira)" <ji...@apache.org> on 2021/01/14 14:57:00 UTC

[jira] [Updated] (HADOOP-17467) netgroup-user does not refresh

     [ https://issues.apache.org/jira/browse/HADOOP-17467?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ahmed Hussein updated HADOOP-17467:
-----------------------------------
    Summary: netgroup-user does not refresh  (was: netgroup-user mapping breaks by a race in NetgroupCache )

> netgroup-user does not refresh
> ------------------------------
>
>                 Key: HADOOP-17467
>                 URL: https://issues.apache.org/jira/browse/HADOOP-17467
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: security
>            Reporter: Ahmed Hussein
>            Assignee: Ahmed Hussein
>            Priority: Major
>
> There is potential concurrency bug in the {{NetgroupCache}} implementation.
> {{NetgroupCache}} is static. When ACL is built, its groups will be added to the {{NetgroupCache}}.
> A {{-refreshUserToGroupsMappings}} forces the cache to reload the users for each group.
> This is done by first getting the keys, clearing the cache, then finally reloading the users for each group.
> The problem that the three steps are not atomic.
> Adding ACLs concurrently may take place between L80-L81 ([JniBasedUnixGroupsNetgroupMapping#L79|https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/JniBasedUnixGroupsNetgroupMapping.java#L79]). This results in the loss of the most recently added group.
> Since group names are used in the JNI level, the users of that group won't be retrieved.
> {code:java}
> 78 @Override
> 79  public void cacheGroupsRefresh() throws IOException {
> 80    List<String> groups = NetgroupCache.getNetgroupNames();
> 81     NetgroupCache.clear();
> 82    cacheGroupsAdd(groups);
> 83  }
> {code}
> +Solution:+
> Refreshing {{NetgroupCache}} should not clear the cache keys. 



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