Make it possible to read from or write to skb metadata area using the
dynptr slices creates with bpf_dynptr_slice() or bpf_dynptr_slice_rdwr().
This prepares ground for access to skb metadata from all BPF hooks
which operate on __sk_buff context.
Signed-off-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
---
net/core/filter.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index ab6599f42bb7..020da46f93a7 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -12033,9 +12033,14 @@ void *bpf_dynptr_skb_slice(const struct bpf_dynptr_kern *ptr, u32 offset,
else
return skb_pointer_if_linear(skb, offset, len);
- case SKB_DYNPTR_METADATA:
- return NULL; /* not implemented */
+ case SKB_DYNPTR_METADATA: {
+ u32 meta_len = skb_metadata_len(skb);
+ if (len > meta_len || offset > meta_len - len)
+ return NULL; /* out of bounds */
+
+ return skb_metadata_end(skb) - meta_len + offset;
+ }
default:
WARN_ONCE(true, "%s: unknown skb dynptr offset %d\n", __func__, ptr->offset);
return NULL;
--
2.43.0
