[PATCH v4 bpf-next 5/9] bpf, xdp: implement LINK_UPDATE for BPF XDP link
From: Andrii Nakryiko <hidden>
Date: 2020-07-22 06:46:25
Also in:
bpf
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Add support for LINK_UPDATE command for BPF XDP link to enable reliable replacement of underlying BPF program. Signed-off-by: Andrii Nakryiko <redacted> --- net/core/dev.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+)
diff --git a/net/core/dev.c b/net/core/dev.c
index f916072f31de..44264eff7f1c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -8996,9 +8996,52 @@ static void bpf_xdp_link_dealloc(struct bpf_link *link) kfree(xdp_link); } +static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog *new_prog, + struct bpf_prog *old_prog) +{ + struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link); + enum bpf_xdp_mode mode; + bpf_op_t bpf_op; + int err = 0; + + rtnl_lock(); + + /* link might have been auto-released already, so fail */ + if (!xdp_link->dev) { + err = -ENOLINK; + goto out_unlock; + } + + if (old_prog && link->prog != old_prog) { + err = -EPERM; + goto out_unlock; + } + old_prog = link->prog; + if (old_prog == new_prog) { + /* no-op, don't disturb drivers */ + bpf_prog_put(new_prog); + goto out_unlock; + } + + mode = dev_xdp_mode(xdp_link->flags); + bpf_op = dev_xdp_bpf_op(xdp_link->dev, mode); + err = dev_xdp_install(xdp_link->dev, mode, bpf_op, NULL, + xdp_link->flags, new_prog); + if (err) + goto out_unlock; + + old_prog = xchg(&link->prog, new_prog); + bpf_prog_put(old_prog); + +out_unlock: + rtnl_unlock(); + return err; +} + static const struct bpf_link_ops bpf_xdp_link_lops = { .release = bpf_xdp_link_release, .dealloc = bpf_xdp_link_dealloc, + .update_prog = bpf_xdp_link_update, }; int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
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2.24.1