bpf: simplify xdp_convert_ctx_access for xdp_rxq_info

As pointed out by Daniel Borkmann, using bpf_target_off() is not
necessary for xdp_rxq_info when extracting queue_index and
ifindex, as these members are u32 like BPF_W.

Also fix trivial spelling mistake introduced in same commit.

Fixes: 02dd3291b2f0 ("bpf: finally expose xdp_rxq_info to XDP bpf-programs")
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

2 files changed, 4 insertions, 5 deletions

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 405317f9c064..395d261948de 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -899,7 +899,7 @@ struct xdp_md {
         __u32 data;
         __u32 data_end;
         __u32 data_meta;
-        /* Below access go though struct xdp_rxq_info */
+        /* Below access go through struct xdp_rxq_info */
         __u32 ingress_ifindex; /* rxq->dev->ifindex */
         __u32 rx_queue_index;  /* rxq->queue_index  */
 };
diff --git a/net/core/filter.c b/net/core/filter.c
index d4b190e63b79..db2ee8c7e1bd 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4310,16 +4310,15 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type,
                                       si->dst_reg, si->dst_reg,
                                       offsetof(struct xdp_rxq_info, dev));
                 *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
-                                      bpf_target_off(struct net_device,
-                                                     ifindex, 4, target_size));
+                                      offsetof(struct net_device, ifindex));
                 break;
         case offsetof(struct xdp_md, rx_queue_index):
                 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff, rxq),
                                       si->dst_reg, si->src_reg,
                                       offsetof(struct xdp_buff, rxq));
                 *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
-                                      bpf_target_off(struct xdp_rxq_info,
-                                                queue_index, 4, target_size));
+                                      offsetof(struct xdp_rxq_info,
+                                               queue_index));
                 break;
         }