From: Daniel Borkmann <dan...@iogearbox.net>
Date: Mon, 3 Aug 2015 16:21:57 +0200
> Since the introduction of the BPF action in d23b8ad8ab23 ("tc: add BPF
> based action"), late binding was not working as expected. I.e. setting
> the action part for a classifier only via 'bpf index <num>', where <num>
> is the index of an existing action, is being rejected by the kernel due
> to other missing parameters.
>
> It doesn't make sense to require these parameters such as BPF opcodes
> etc, as they are not going to be used anyway: in this case, they're just
> allocated/parsed and then freed again w/o doing anything meaningful.
>
> Instead, parse and verify the remaining parameters *after* the test on
> tcf_hash_check(), when we really know that we're dealing with creation
> of a new action or replacement of an existing one and where late binding
> is thus irrelevant.
>
> After patch, test case is now working:
>
> FOO="1,6 0 0 4294967295,"
> tc actions add action bpf bytecode "$FOO"
> tc filter add dev foo parent 1: bpf bytecode "$FOO" flowid 1:1 action bpf
> index 1
> tc actions show action bpf
> action order 0: bpf bytecode '1,6 0 0 4294967295' default-action pipe
> index 1 ref 2 bind 1
> tc filter show dev foo
> filter protocol all pref 49152 bpf
> filter protocol all pref 49152 bpf handle 0x1 flowid 1:1 bytecode '1,6 0
> 0 4294967295'
> action order 1: bpf bytecode '1,6 0 0 4294967295' default-action pipe
> index 1 ref 2 bind 1
>
> Late binding of a BPF action can be useful for preloading maps (e.g. before
> they hit traffic) in case of eBPF programs, or to share a single eBPF action
> with multiple classifiers.
>
> Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
Applied to net-next, thanks Daniel.
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