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  1. Mar 25, 2021
  3. Mar 24, 2021
    • Vladimir Oltean's avatar
      net: bridge: don't notify switchdev for local FDB addresses · 6ab4c311
      Vladimir Oltean authored 
      As explained in this discussion:
https://lore.kernel.org/netdev/20210117193009.io3nungdwuzmo5f7@skbuf/

the switchdev notifiers for FDB entries managed to have a zero-day bug.
The bridge would not say that this entry is local:

ip link add br0 type bridge
ip link set swp0 master br0
bridge fdb add dev swp0 00:01:02:03:04:05 master local

and the switchdev driver would be more than happy to offload it as a
normal static FDB entry. This is despite the fact that 'local' and
non-'local' entries have completely opposite directions: a local entry
is locally terminated and not forwarded, whereas a static entry is
forwarded and not locally terminated. So, for example, DSA would install
this entry on swp0 instead of installing it on the CPU port as it should.

There is an even sadder part, which is that the 'local' flag is implicit
if 'static' is not specified, meaning that this command produces the
same result of adding a 'local' entry:

bridge fdb add dev swp0 00:01:02:03:04:05 master

I've updated the man pages for 'bridge', and after reading it now, it
should be pretty clear to any user that the commands above were broken
and should have never resulted in the 00:01:02:03:04:05 address being
forwarded (this behavior is coherent with non-switchdev interfaces):
https://patchwork.kernel.org/project/netdevbpf/cover/20210211104502.2081443-1-olteanv@gmail.com/
If you're a user reading this and this is what you want, just use:

bridge fdb add dev swp0 00:01:02:03:04:05 master static

Because switchdev should have given drivers the means from day one to
classify FDB entries as local/non-local, but didn't, it means that all
drivers are currently broken. So we can just as well omit the switchdev
notifications for local FDB entries, which is exactly what this patch
does to close the bug in stable trees. For further development work
where drivers might want to trap the local FDB entries to the host, we
can add a 'bool is_local' to br_switchdev_fdb_call_notifiers(), and
selectively make drivers act upon that bit, while all the others ignore
those entries if the 'is_local' bit is set.

Fixes: 6b26b51b

 ("net: bridge: Add support for notifying devices about FDB add/del")
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      6ab4c311
    • Marcelo Ricardo Leitner's avatar
      net/sched: act_ct: clear post_ct if doing ct_clear · 8ca1b090
      Marcelo Ricardo Leitner authored 
      Invalid detection works with two distinct moments: act_ct tries to find
a conntrack entry and set post_ct true, indicating that that was
attempted. Then, when flow dissector tries to dissect CT info and no
entry is there, it knows that it was tried and no entry was found, and
synthesizes/sets
                  key->ct_state = TCA_FLOWER_KEY_CT_FLAGS_TRACKED |
                                  TCA_FLOWER_KEY_CT_FLAGS_INVALID;
mimicing what OVS does.

OVS has this a bit more streamlined, as it recomputes the key after
trying to find a conntrack entry for it.

Issue here is, when we have 'tc action ct clear', it didn't clear
post_ct, causing a subsequent match on 'ct_state -trk' to fail, due to
the above. The fix, thus, is to clear it.

Reproducer rules:
tc filter add dev enp130s0f0np0_0 ingress prio 1 chain 0 \
	protocol ip flower ip_proto tcp ct_state -trk \
	action ct zone 1 pipe \
	action goto chain 2
tc filter add dev enp130s0f0np0_0 ingress prio 1 chain 2 \
	protocol ip flower \
	action ct clear pipe \
	action goto chain 4
tc filter add dev enp130s0f0np0_0 ingress prio 1 chain 4 \
	protocol ip flower ct_state -trk \
	action mirred egress redirect dev enp130s0f1np1_0

With the fix, the 3rd rule matches, like it does with OVS kernel
datapath.

Fixes: 7baf2429

 ("net/sched: cls_flower add CT_FLAGS_INVALID flag support")
Signed-off-by: default avatarMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Reviewed-by: default avatarwenxu <wenxu@ucloud.cn>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8ca1b090
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