From: Andrii Nakryiko <andriin@fb.com>
Date: Tue, 21 Jul 2020 23:45:58 -0700
Subject: bpf, xdp: Implement LINK_UPDATE for BPF XDP link
Patch-mainline: v5.9-rc1
Git-commit: 026a4c28e1db3b0cb99cd9a3e495d4a8b632fa74
References: bsc#1177028
Add support for LINK_UPDATE command for BPF XDP link to enable reliable
replacement of underlying BPF program.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-6-andriin@fb.com
Acked-by: Gary Lin <glin@suse.com>
---
net/core/dev.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9016,9 +9016,52 @@ static void bpf_xdp_link_dealloc(struct
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)