Re: Linux kernel scm_send local DoS

["Pavel Kankovsky" <peak () argo troja mff cuni cz>]

On Tue, 14 Dec 2004, Paul Starzetz wrote:

> The Linux kernel provides a powerful socket API  to  user  applications.
> Among other functions sockets provide an universal way for IPC and user-
> kernel communication. The socket layer uses several  logical  sublayers.
> One  of  the  layers,  so called auxiliary message layer (or scm layer),
> augments the socket API by  an  universal  user-kernel  message  passing
> capability (see recvfrom(2) for more details on auxiliary messages).

More nasties might be lurking nearby (at least in 2.4):

- additional, almost identical, copies of cmsg parsing code appear in
  ip_cmsg_send() (net/ipv4/ip_sockglue.c) and datagram_send_ctl()
  (net/ipv6/datagram.c)

- sys_sendmsg() (net/socket.c) is willing to allocate almost arbitrary 
  large blocks of kernel memory


--Pavel Kankovsky aka Peak  [ Boycott Microsoft--http://www.vcnet.com/bms ]
"Resistance is futile. Open your source code and prepare for assimilation."