TIOCSETD with PPP, mkiss, etc

Hi,

Wouldn't it be safer if the ldisc open function for PPP, mkiss etc included a check for CAP_NET_ADMIN privilege, and reject the attempt to set the line discipline if the user is not privileged? The slip module already has this check, but other modules don't.

I looked at various protocol modules (ppp sync/async, mkiss, irtty, ...) and there is no immediate security problem; these modules either do not allocate a netdevice, or if they do, they check for netif_running() before they pass the decoded packet to the network layer.

Still I think it's somewhat dangerous to allow a user to open a pty pair, set the slave's line discipline and feed it whatever he likes.

Olaf

Olaf Kirch     | Things that make Monday morning interesting, #2:
[email protected]   |        "We have 8,000 NFS mount points, why do we keep
---------------+ 	 running out of privileged ports?"