* Grow or shrink the room for data in the packet associated to
* *skb* by *len_diff*, and according to the selected *mode*.
*
- * There is a single supported mode at this time:
+ * There are two supported modes at this time:
+ *
+ * * **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
+ * (room space is added or removed below the layer 2 header).
*
* * **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
* (room space is added or removed below the layer 3 header).
/* Mode for BPF_FUNC_skb_adjust_room helper. */
enum bpf_adj_room_mode {
BPF_ADJ_ROOM_NET,
+ BPF_ADJ_ROOM_MAC,
};
/* Mode for BPF_FUNC_skb_load_bytes_relative helper. */
}
}
-static int bpf_skb_net_grow(struct sk_buff *skb, u32 len_diff)
+static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff)
{
- u32 off = skb_mac_header_len(skb) + bpf_skb_net_base_len(skb);
int ret;
if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
return 0;
}
-static int bpf_skb_net_shrink(struct sk_buff *skb, u32 len_diff)
+static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff)
{
- u32 off = skb_mac_header_len(skb) + bpf_skb_net_base_len(skb);
int ret;
if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
SKB_MAX_ALLOC;
}
-static int bpf_skb_adjust_net(struct sk_buff *skb, s32 len_diff)
+BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
+ u32, mode, u64, flags)
{
bool trans_same = skb->transport_header == skb->network_header;
u32 len_cur, len_diff_abs = abs(len_diff);
u32 len_max = __bpf_skb_max_len(skb);
__be16 proto = skb->protocol;
bool shrink = len_diff < 0;
+ u32 off;
int ret;
+ if (unlikely(flags))
+ return -EINVAL;
if (unlikely(len_diff_abs > 0xfffU))
return -EFAULT;
if (unlikely(proto != htons(ETH_P_IP) &&
proto != htons(ETH_P_IPV6)))
return -ENOTSUPP;
+ off = skb_mac_header_len(skb);
+ switch (mode) {
+ case BPF_ADJ_ROOM_NET:
+ off += bpf_skb_net_base_len(skb);
+ break;
+ case BPF_ADJ_ROOM_MAC:
+ break;
+ default:
+ return -ENOTSUPP;
+ }
+
len_cur = skb->len - skb_network_offset(skb);
if (skb_transport_header_was_set(skb) && !trans_same)
len_cur = skb_network_header_len(skb);
!skb_is_gso(skb))))
return -ENOTSUPP;
- ret = shrink ? bpf_skb_net_shrink(skb, len_diff_abs) :
- bpf_skb_net_grow(skb, len_diff_abs);
+ ret = shrink ? bpf_skb_net_shrink(skb, off, len_diff_abs) :
+ bpf_skb_net_grow(skb, off, len_diff_abs);
bpf_compute_data_pointers(skb);
return ret;
}
-BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
- u32, mode, u64, flags)
-{
- if (unlikely(flags))
- return -EINVAL;
- if (likely(mode == BPF_ADJ_ROOM_NET))
- return bpf_skb_adjust_net(skb, len_diff);
-
- return -ENOTSUPP;
-}
-
static const struct bpf_func_proto bpf_skb_adjust_room_proto = {
.func = bpf_skb_adjust_room,
.gpl_only = false,