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https://issues.apache.org/jira/browse/HADOOP-17467?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ahmed Hussein updated HADOOP-17467:
-----------------------------------
Description:
After the optimization in HADOOP-17079, {{JniBasedUnixGroupsNetgroupMapping}}
does not implement {{getGroupSet}}.
As a result, {{Groups.load()}} load the cache calling {{fetchGroupSet}} which
got
to the superclass {{JniBasedUnixGroupsMapping}}.
In other words, the groups mapping will never fetch from {{NetgroupCache}}.
This alters the behavior of the implementation. Is there a reason to bypass
loading. CC: [~xyao]
was:
After the optimization in HADOOP-17079, {{JniBasedUnixGroupsNetgroupMapping}}
does not implement {{getGroupSet}}.
As a result, {{Groups.load()}} load the cache calling {{fetchGroupSet}} which
got
to the superclass {{JniBasedUnixGroupsMapping}}.
In other words, the groups mapping will never fetch from {{NetgroupCache}}.
This alters the behavior of the implementation. Is there a reason to bypass
loading. CC: [~xyao]
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.
> netgroup-user is not added to Groups.cache
> ------------------------------------------
>
> 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
> Labels: pull-request-available
> Time Spent: 2h 10m
> Remaining Estimate: 0h
>
> After the optimization in HADOOP-17079, {{JniBasedUnixGroupsNetgroupMapping}}
> does not implement {{getGroupSet}}.
> As a result, {{Groups.load()}} load the cache calling {{fetchGroupSet}}
> which got
> to the superclass {{JniBasedUnixGroupsMapping}}.
> In other words, the groups mapping will never fetch from {{NetgroupCache}}.
> This alters the behavior of the implementation. Is there a reason to bypass
> loading. CC: [~xyao]
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