[net,0/3] net/sched: act_ipt bug fixes

Message

Florian Westphal June 7, 2023, 2:59 p.m. UTC

While checking if netfilter could be updated to replace selected
instances of NF_DROP with kfree_skb_reason+NF_STOLEN to improve
debugging info via drop monitor I found that act_ipt is incompatible
with such an approach.  Moreover, it lacks multiple sanity checks
to avoid certain code paths that make assumptions that the tc layer
doesn't meet, such as header sanity checks, availability of skb_dst,
skb_nfct() and so on.

act_ipt test in the tc selftest still pass with this applied.

I think that we should consider removal of this module, while
this should take care of all problems, its ipv4 only and I don't
think there are any netfilter targets that lack a native tc
equivalent, even when ignoring bpf.

Florian Westphal (3):
  net/sched: act_ipt: add sanity checks on table name and hook locations
  net/sched: act_ipt: add sanity checks on skb before calling target
  net/sched: act_ipt: zero skb->cb before calling target

 net/sched/act_ipt.c | 70 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 63 insertions(+), 7 deletions(-)