[jira] [Commented] (HDFS-4765) Permission check of symlink deletion incorrectly throws UnresolvedLinkException

["Aaron T. Myers (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-4765?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13654790#comment-13654790 ] 

Aaron T. Myers commented on HDFS-4765:
--------------------------------------

Patch looks pretty good to me, Andrew, though it no longer applies to trunk after the snapshot merge so it will need to be rebased somewhat. Two little suggestions:

# Recommend you use the two argument versions of assertTrue and assertFalse which take error messages to display in the event the assertion fails.
# Though not introduced by this patch, I notice that the indentation in FSPermissionChecker#checkPermission is off. Mind fixing that while you're in there?

+1 once these are addressed.
                
> Permission check of symlink deletion incorrectly throws UnresolvedLinkException
> -------------------------------------------------------------------------------
>
>                 Key: HDFS-4765
>                 URL: https://issues.apache.org/jira/browse/HDFS-4765
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 3.0.0, 2.0.3-alpha
>            Reporter: Andrew Wang
>            Assignee: Andrew Wang
>         Attachments: hdfs-4765-1.patch
>
>
> With permissions enabled, the permission check in {{FSNamesystem#delete}} will incorrectly throw an UnresolvedLinkException if the path contains a symlink. This leads to FileContext resolving the symlink and instead deleting the link target.
> The correct check is to see if the user has write permissions on the parent directory of the symlink, e.g.
> {noformat}
> -> % ls -ld symtest
> drwxr-xr-x 2 root root 4096 Apr 26 14:12 symtest
> -> % ls -l symtest
> total 12
> lrwxrwxrwx 1 root root 6 Apr 26 14:12 link -> target
> -rw-r--r-- 1 root root 0 Apr 26 14:11 target
> -> % rm -f symtest/link
> rm: cannot remove `symtest/link': Permission denied
> -> % sudo chown andrew symtest
> -> % rm -f symtest/link       
> -> % 
> {noformat}

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