On Wed, May 15, 2019 at 10:54 PM Theo de Raadt <dera...@openbsd.org> wrote:
> Martijn van Duren <openbsd+t...@list.imperialat.at> wrote: > > > I don't see much point in the check. > > > > If we don't have write permissions open(2) will fail. > > If we open it based on S_IWOTH permissions than checking for S_IWGRP > > without considering who is in that group seems really absurd to me. > > > > So I'd be OK with patch 1 > > There are 3 write permission checks which could permit the open, > but then it checks the specific one. > > I believe this is similar to comsat / biff, which in those programs > are used to indicate "I am ok with messages to my tty". > > That is an old behaviour, but I bet that is the history of this S_IWGRP > check. > Yep. mesg(1) manipulates your tty's group-write bit so that wall(1), talk(1), and write(1) can check it. Philip Guenther
