On Tue, Apr 25, 2017 at 3:47 PM, Alan Cox <gnomes@xxxxxxxxxxxxxxxxxxx> wrote: >> There could be a few user programs that would be effected by this >> change. >> See: <https://codesearch.debian.net/search?q=ioctl%5C%28.*TIOCSTI> >> notable programs are: agetty, csh, xemacs and tcsh >> >> However, I still believe that this change is worth it given that the >> Kconfig defaults to n. This will be a feature that is turned on for the >> same reason that people activate it when using grsecurity. Users of this >> opt-in feature will realize that they are choosing security over some OS >> features > > Only in this case they are not. > > If I am at the point I have the ability to send you TIOCSTI you already > lost because I can just open /dev/tty to get access to my controlling tty > and use write(). In terms of PTYs, this patch does not try to prevent writes to a slave device (which afaik is what /dev/tty will give you). It tries to prevent the equivalent of writes to the master device. As far as I know, there is no way to go from a slave to the corresponding master without having access to the master in some other way already. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
