Here is a case i don't understand
i have a group 'bar', and this group has two users; 'foo' and 'bar'.
I have a test.txt file, 'foo' is the owner and 'bar' user only can read it.
However, if 'bar' user run gzip command to this file, the ownership changes from 'foo' to 'bar'.
Therefore, 'foo' cannot touch this file any more. Is this a security hole?
logged in as 'bar'
$ whoami bar $ cd /home/foo/test $ ls -al total 8 drwxrwxr-x 2 foo bar 4096 Jan 6 15:48 . drwxrwxr-- 5 foo bar 4096 Jan 6 15:48 .. -rwxr-xr-x 1 foo foo 0 Jan 6 15:48 test.txt $ gzip test.txt $ ls -al total 12 drwxrwxr-x 2 foo bar 4096 Jan 6 15:50 . drwxrwxr-- 5 foo bar 4096 Jan 6 15:48 .. -rwxr-xr-x 1 bar bar 29 Jan 6 15:48 test.txt.gz $ uname -a Linux 2.6.18-xenU-ec2-v1.2 #2 SMP x86_64 x86_64 x86_64 GNU/Linux
logged in as a 'foo'
$ whoami foo $ touch test.txt.gz touch: cannot touch `test.txt.gz': Permission denied