From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Mon, 26 Aug 2024 13:03:23 +0000 (+0200)
Subject: netfilter: nf_tables_ipv6: consider network offset in netdev/egress validation
X-Git-Tag: v6.11-rc6~24^2~1^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=70c261d500951cf3ea0fcf32651aab9a65a91471;p=thirdparty%2Fkernel%2Flinux.git

netfilter: nf_tables_ipv6: consider network offset in netdev/egress validation

From netdev/egress, skb->len can include the ethernet header, therefore,
subtract network offset from skb->len when validating IPv6 packet length.

Fixes: 42df6e1d221d ("netfilter: Introduce egress hook")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---

diff --git a/include/net/netfilter/nf_tables_ipv6.h b/include/net/netfilter/nf_tables_ipv6.h
index 467d59b9e5334..a0633eeaec977 100644
--- a/include/net/netfilter/nf_tables_ipv6.h
+++ b/include/net/netfilter/nf_tables_ipv6.h
@@ -31,8 +31,8 @@ static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt)
 	struct ipv6hdr *ip6h, _ip6h;
 	unsigned int thoff = 0;
 	unsigned short frag_off;
+	u32 pkt_len, skb_len;
 	int protohdr;
-	u32 pkt_len;
 
 	ip6h = skb_header_pointer(pkt->skb, skb_network_offset(pkt->skb),
 				  sizeof(*ip6h), &_ip6h);
@@ -43,7 +43,8 @@ static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt)
 		return -1;
 
 	pkt_len = ntohs(ip6h->payload_len);
-	if (pkt_len + sizeof(*ip6h) > pkt->skb->len)
+	skb_len = pkt->skb->len - skb_network_offset(pkt->skb);
+	if (pkt_len + sizeof(*ip6h) > skb_len)
 		return -1;
 
 	protohdr = ipv6_find_hdr(pkt->skb, &thoff, -1, &frag_off, &flags);