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Date: Wed, 5 Oct 2022 20:19:33 -0700 From: Andrii Nakryiko <andrii.nakryiko@...il.com> To: Daniel Borkmann <daniel@...earbox.net> Cc: bpf@...r.kernel.org, razor@...ckwall.org, ast@...nel.org, andrii@...nel.org, martin.lau@...ux.dev, john.fastabend@...il.com, joannelkoong@...il.com, memxor@...il.com, toke@...hat.com, joe@...ium.io, netdev@...r.kernel.org Subject: Re: [PATCH bpf-next 05/10] bpf: Implement link detach for tc BPF link programs On Tue, Oct 4, 2022 at 4:12 PM Daniel Borkmann <daniel@...earbox.net> wrote: > > Add support for forced detach operation of tc BPF link. This detaches the link > but without destroying it. It has the same semantics as auto-detaching of BPF > link due to e.g. net device being destroyed for tc or XDP BPF link. Meaning, > in this case the BPF link is still a valid kernel object, but is defunct given > it is not attached anywhere anymore. It still holds a reference to the BPF > program, though. This functionality allows users with enough access rights to > manually force-detach attached tc BPF link without killing respective owner > process and to then introspect/debug the BPF assets. Similar LINK_DETACH exists > also for other BPF link types. > > Co-developed-by: Nikolay Aleksandrov <razor@...ckwall.org> > Signed-off-by: Nikolay Aleksandrov <razor@...ckwall.org> > Signed-off-by: Daniel Borkmann <daniel@...earbox.net> > --- Acked-by: Andrii Nakryiko <andrii@...nel.org> > kernel/bpf/net.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kernel/bpf/net.c b/kernel/bpf/net.c > index a74b86bb60a9..5650f62c1315 100644 > --- a/kernel/bpf/net.c > +++ b/kernel/bpf/net.c > @@ -350,6 +350,12 @@ static void xtc_link_release(struct bpf_link *l) > rtnl_unlock(); > } > > +static int xtc_link_detach(struct bpf_link *l) > +{ > + xtc_link_release(l); > + return 0; > +} > + > static void xtc_link_dealloc(struct bpf_link *l) > { > struct bpf_tc_link *link = container_of(l, struct bpf_tc_link, link); > @@ -393,6 +399,7 @@ static int xtc_link_fill_info(const struct bpf_link *l, > > static const struct bpf_link_ops bpf_tc_link_lops = { > .release = xtc_link_release, > + .detach = xtc_link_detach, > .dealloc = xtc_link_dealloc, > .update_prog = xtc_link_update, > .show_fdinfo = xtc_link_fdinfo, > -- > 2.34.1 >
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