[PATCH v4 bpf-next 6/9] bpf: implement BPF XDP link-specific introspection APIs

[Andrii Nakryiko]

Implement XDP link-specific show_fdinfo and link_info to emit ifindex.

Signed-off-by: Andrii Nakryiko <andr...@fb.com>
---
 include/uapi/linux/bpf.h |  3 +++
 net/core/dev.c           | 31 +++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 1da0c2984e7f..27bd1c8b0041 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4062,6 +4062,9 @@ struct bpf_link_info {
                        __u32 netns_ino;
                        __u32 attach_type;
                } netns;
+               struct {
+                       __u32 ifindex;
+               } xdp;
        };
 } __attribute__((aligned(8)));
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 44264eff7f1c..9859dae7d4dc 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8996,6 +8996,35 @@ static void bpf_xdp_link_dealloc(struct bpf_link *link)
        kfree(xdp_link);
 }
 
+static void bpf_xdp_link_show_fdinfo(const struct bpf_link *link,
+                                    struct seq_file *seq)
+{
+       struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, 
link);
+       u32 ifindex = 0;
+
+       rtnl_lock();
+       if (xdp_link->dev)
+               ifindex = xdp_link->dev->ifindex;
+       rtnl_unlock();
+
+       seq_printf(seq, "ifindex:\t%u\n", ifindex);
+}
+
+static int bpf_xdp_link_fill_link_info(const struct bpf_link *link,
+                                      struct bpf_link_info *info)
+{
+       struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, 
link);
+       u32 ifindex = 0;
+
+       rtnl_lock();
+       if (xdp_link->dev)
+               ifindex = xdp_link->dev->ifindex;
+       rtnl_unlock();
+
+       info->xdp.ifindex = ifindex;
+       return 0;
+}
+
 static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog 
*new_prog,
                               struct bpf_prog *old_prog)
 {
@@ -9041,6 +9070,8 @@ static int bpf_xdp_link_update(struct bpf_link *link, 
struct bpf_prog *new_prog,
 static const struct bpf_link_ops bpf_xdp_link_lops = {
        .release = bpf_xdp_link_release,
        .dealloc = bpf_xdp_link_dealloc,
+       .show_fdinfo = bpf_xdp_link_show_fdinfo,
+       .fill_link_info = bpf_xdp_link_fill_link_info,
        .update_prog = bpf_xdp_link_update,
 };
 
-- 
2.24.1