On Tue, Sep 8, 2020 at 6:23 PM Xie He <xie.he.0...@gmail.com> wrote: > > On Tue, Sep 8, 2020 at 4:53 AM Willem de Bruijn > <willemdebruijn.ker...@gmail.com> wrote: > > > > On Tue, Sep 8, 2020 at 1:04 PM Xie He <xie.he.0...@gmail.com> wrote: > > > > > > I was recently looking at some drivers, and I felt that if af_packet.c > > > could help me filter out the invalid RAW frames, I didn't need to > > > check the validity of the frames myself (in the driver when > > > transmitting). But now I guess I still need to check that. > > > > > > I feel this makes the dev_validate_header's variable-length header > > > check not very useful, because drivers need to do this check again > > > (when transmitting) anyway. > > > > > > I was thinking, after I saw dev_validate_header, that we could > > > eventually make it completely take over the responsibility for a > > > driver to validate the header when transmitting RAW frames. But now it > > > seems we would not be able to do this. > > > > Agreed. As is, it is mainly useful to block users who are ns_capable, > > but not capable. > > > > A third option is to move it behind a sysctl (with static_branch). Your > > point is valid that there really is no need for testing of drivers against > > bad packets if the data is validated directly on kernel entry. > > I was thinking about this again and it came to me that maybe sometimes > people actually wanted to send invalid frames on wire (for testing the > network device on the other end of the wire)? Having thought about > this possibility I think it might be good to keep the ability for > people to have 2 choices (either having their RAW frames validated, or > not validated) through "capability" or through "sysctl" as you > mentioned. We can keep the default to be not validating the RAW frames > because RAW sockets are already intended for very special use and are > not for normal use.
That offers some configurability. But really, I would just leave it as is.
