netfilter: nf_tables_ipv6: consider network offset in netdev/egress validation
[ Upstream commit 70c261d500951cf3ea0fcf32651aab9a65a91471 ]
From netdev/egress, skb->len can include the ethernet header, therefore,
subtract network offset from skb->len when validating IPv6 packet length.
Fixes: 42df6e1d22
("netfilter: Introduce egress hook")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -31,8 +31,8 @@ static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt)
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struct ipv6hdr *ip6h, _ip6h;
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unsigned int thoff = 0;
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unsigned short frag_off;
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u32 pkt_len, skb_len;
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int protohdr;
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u32 pkt_len;
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ip6h = skb_header_pointer(pkt->skb, skb_network_offset(pkt->skb),
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sizeof(*ip6h), &_ip6h);
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@ -43,7 +43,8 @@ static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt)
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return -1;
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pkt_len = ntohs(ip6h->payload_len);
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if (pkt_len + sizeof(*ip6h) > pkt->skb->len)
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skb_len = pkt->skb->len - skb_network_offset(pkt->skb);
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if (pkt_len + sizeof(*ip6h) > skb_len)
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return -1;
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protohdr = ipv6_find_hdr(pkt->skb, &thoff, -1, &frag_off, &flags);
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