[HDFS-4765] Permission check of symlink deletion incorrectly throws UnresolvedLinkException

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.3-alpha, 3.0.0-alpha1
• Fix Version/s: 2.1.0-beta, 0.23.9
• Component/s: namenode
• Hadoop Flags: Reviewed
• Assignee: Andrew Wang
• Reporter: Andrew Wang
• Created: 26/Apr/13 21:15
• Updated: 12/May/16 18:13
• Resolved: 13/May/13 18:14

Description

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.

-> % 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       
-> % 

Issue Links

• blocks: HDFS-5067 Support symlink operations