Make it possible to read from skb metadata area using the
bpf_dynptr_read() BPF helper.
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 | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 3c2948517838..f71b4b6b09fb 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -11981,9 +11981,15 @@ int bpf_dynptr_skb_read(const struct bpf_dynptr_kern *src, u32 offset,
case SKB_DYNPTR_PAYLOAD:
return ____bpf_skb_load_bytes(skb, offset, dst, len);
- case SKB_DYNPTR_METADATA:
- return -EOPNOTSUPP; /* not implemented */
+ case SKB_DYNPTR_METADATA: {
+ u32 meta_len = skb_metadata_len(skb);
+
+ if (len > meta_len || offset > meta_len - len)
+ return -E2BIG; /* out of bounds */
+ memmove(dst, skb_metadata_end(skb) - meta_len + offset, len);
+ return 0;
+ }
default:
WARN_ONCE(true, "%s: unknown skb dynptr offset %d\n", __func__, src->offset);
return -EFAULT;
--
2.43.0
