Make it clear that this XDP program depend on the network
stack to do the ARP resolution. This is connected with the
BPF_FIB_LKUP_RET_NO_NEIGH return code from bpf_fib_lookup().
Another common mistake (seen via XDP-tutorial) is that users
don't realize that sysctl net.ipv{4,6}.conf.all.forwarding
setting is honored by bpf_fib_lookup.
Reported-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This address the TODO in samples/bpf/xdp_fwd_kern.c, which points out
that the chosen egress index should be checked for existence in the
devmap. This can now be done via taking advantage of Toke's work in
commit 0cdbb4b09a ("devmap: Allow map lookups from eBPF").
This change makes xdp_fwd more practically usable, as this allows for
a mixed environment, where IP-forwarding fallback to network stack, if
the egress device isn't configured to use XDP.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The devmap name 'tx_port' came from a copy-paste from xdp_redirect_map
which only have a single TX port. Change name to xdp_tx_ports
to make it more descriptive.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
For ACLs implemented using either FIB rules or FIB entries, the BPF
program needs the FIB lookup status to be able to drop the packet.
Since the bpf_fib_lookup API has not reached a released kernel yet,
change the return code to contain an encoding of the FIB lookup
result and return the nexthop device index in the params struct.
In addition, inform the BPF program of any post FIB lookup reason as
to why the packet needs to go up the stack.
The fib result for unicast routes must have an egress device, so remove
the check that it is non-NULL.
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
As Michal noted the flow struct takes both the flow label and priority.
Update the bpf_fib_lookup API to note that it is flowinfo and not just
the flow label.
Cc: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Only consider forwarding packets if ttl in received packet is > 1 and
decrement ttl before handing off to bpf_redirect_map.
Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Simple example of fast-path forwarding. It has a serious flaw
in not verifying the egress device index supports XDP forwarding.
If the egress device does not packets are dropped.
Take this only as a simple example of fast-path forwarding.
Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Jesper Dangaard Brouer