Re: Directory/File Access Permissions for COPY and Generic File Access Functions

Stephen Frost <sfrost(at)snowman(dot)net> writes:
> * Tom Lane (tgl(at)sss(dot)pgh(dot)pa(dot)us) wrote:
>> No such file in RHEL 6.6 :-(.

> Ouch. Although- have you tested when happens there?

Pretty much exactly the same thing I just saw on OSX, ie, nothing.

[tgl(at)sss1 zzz]$ touch foo
[tgl(at)sss1 zzz]$ ls -l
total 0
-rw-rw-r--. 1 tgl tgl 0 Oct 29 12:23 foo
[tgl(at)sss1 zzz]$ ln foo bar
[tgl(at)sss1 zzz]$ ls -l
total 0
-rw-rw-r--. 2 tgl tgl 0 Oct 29 12:23 bar
-rw-rw-r--. 2 tgl tgl 0 Oct 29 12:23 foo
[tgl(at)sss1 zzz]$ chmod 000 foo
[tgl(at)sss1 zzz]$ sudo chown root foo
[tgl(at)sss1 zzz]$ ln foo baz
[tgl(at)sss1 zzz]$ ls -l
total 0
----------. 3 root tgl 0 Oct 29 12:23 bar
----------. 3 root tgl 0 Oct 29 12:23 baz
----------. 3 root tgl 0 Oct 29 12:23 foo
[tgl(at)sss1 zzz]$ uname -a
Linux sss1.sss.pgh.pa.us 2.6.32-504.el6.x86_64 #1 SMP Tue Sep 16 01:56:35 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux

> I wonder if
> they've decided it's not worth allowing ever or if they feel that it's
> not worth preventing and that security-concious software should check
> the link count as Andres suggests.

Probably it's just that it's a new feature that they've not chosen to
back-port into 2.6.x kernels. I'm sure they're following the upstream
kernels in newer release series. But even if they had chosen to back-port
it, you can be entirely darn sure it wouldn't be turned on by default in
the RHEL6 series; they'd be too worried about breaking existing
applications.

regards, tom lane