Re: [NFS] [PATCH 2/7] NFS: if ATTR_KILL_S*ID bits are set, then skip mode change



On Tue, Sep 04, 2007 at 10:37:04AM -0400, Jeff Layton wrote:
If the ATTR_KILL_S*ID bits are set then any mode change is only for
clearing the setuid/setgid bits. For NFS skip the mode change and
let the server handle it.

You're assuming the server will remove setuid and setgid bits on WRITE?
I don't see that behaviour specified in the RFC, at least for v3.
The RFC specifies a behaviour for the mtime attribute as a side
effect of WRITE, but says nothing about mode. This means server
implementations are free to clobber setuid or not. A quick experiment
shows that at least the Irix server will *NOT* clobber those bits.
So with an Irix server you've now lost this Linux-specific "security
feature".

I'm curious about the reasons behind this change. You mention
credential issues; how exactly is it that you have the correct creds
to perform a WRITE rpc but not a SETATTR rpc?

Greg.
--
Greg Banks, R&D Software Engineer, SGI Australian Software Group.
Apparently, I'm Bedevere. Which MPHG character are you?
I don't speak for SGI.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/



Relevant Pages

  • Re: Having Tcl script accessing files as a specific user
    ... server that have restricted access. ... Run the script via a special version of tclsh that has the setuid ... it fires off the process that it changes its file owner, ...
    (comp.lang.tcl)
  • Re: Help with passthru()
    ... I want to implement a Web based System administration page in PHP. ... Luckily, in my case, it was a server on our intranet, and I wasn't ... Don't use setuid on web scripts! ... Use cgiwrap to run the scripts as the logged in user rather than the web server's ID. ...
    (comp.lang.php)
  • Re: [NFS] [PATCH 2/7] NFS: if ATTR_KILL_S*ID bits are set, then skip mode change
    ... You're assuming the server will remove setuid and setgid bits on WRITE? ... user1$ echo foo> foo ... the write by user2 fails. ...
    (Linux-Kernel)
  • Re: CGI security on a shared web server (fwd)
    ... > If suexec had an option for specifying which CGI programs to run setuid, ... to apply to all CGI programs on the server. ... setuid user could be restricted with no shell. ...
    (SecProg)
  • Re: Outlook 2003 incoming server entry
    ... sounds like you are running Outlook in 'internet' mode change to 'Exchange ... "Bob" wrote in message ... > OK, big time newbi here. ... > mail server entry in OL 2003. ...
    (microsoft.public.windows.server.sbs)