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https://issues.apache.org/jira/browse/HDFS-5923?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13898370#comment-13898370
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Haohui Mai commented on HDFS-5923:
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The v0 patch takes a more aggressive approach, which removes the ACL bit
completely. The rationale is the following:
# Some applications might assume that {{FsPermission}} stay within the range of
0~0777. Changing {{FsPermission}} might lead to unexpected issues.
# There are not many users care about whether the file has ACL except for ls.
Since ls is not in the critical path, ls can make a separate {{getAclStatus()}}
call to calculate the ACL bit.
> Do not persist the ACL bit in the FsPermission
> ----------------------------------------------
>
> Key: HDFS-5923
> URL: https://issues.apache.org/jira/browse/HDFS-5923
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: hdfs-client, namenode, security
> Reporter: Haohui Mai
> Assignee: Haohui Mai
> Attachments: HDFS-5923.000.patch
>
>
> The current implementation persists and ACL bit in FSImage and editlogs.
> Moreover, the security decisions also depend on whether the bit is set.
> The problem here is that we have to maintain the implicit invariant, which is
> the ACL bit is set if and only if the the inode has AclFeature. The invariant
> has to be maintained everywhere otherwise it can lead to a security
> vulnerability. In the worst case, an attacker can toggle the bit and bypass
> the ACL checks.
> The jira proposes to treat the ACL bit as a transient bit. The bit should not
> be persisted onto the disk, neither it should affect any security decisions.
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