[PATCH bpf-next v3 08/16] bpf: Make bpf_skb_change_proto helper metadata-safe

[Jakub Sitnicki <jakub@cloudflare.com>]

bpf_skb_change_proto reuses the same headroom operations as
bpf_skb_adjust_room, already updated to handle metadata safely.

The remaining step is to ensure that there is sufficient headroom to
accommodate metadata on skb_push().

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
---
 net/core/filter.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 80a7061102b5..09a094546ddb 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3333,10 +3333,11 @@ static int bpf_skb_net_hdr_pop(struct sk_buff *skb, u32 off, u32 len)
 static int bpf_skb_proto_4_to_6(struct sk_buff *skb)
 {
 	const u32 len_diff = sizeof(struct ipv6hdr) - sizeof(struct iphdr);
+	const u8 meta_len = skb_metadata_len(skb);
 	u32 off = skb_mac_header_len(skb);
 	int ret;
 
-	ret = skb_cow(skb, len_diff);
+	ret = skb_cow(skb, meta_len + len_diff);
 	if (unlikely(ret < 0))
 		return ret;
 

-- 
2.43.0