netdev - [PATCH nf-next 3/6] netfilter: bridge: move pskb_trim_rcsum out of br_nf_check_hbh

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Date:   Fri,  3 Mar 2023 19:12:39 -0500
From:   Xin Long <lucien.xin@...il.com>
To:     netfilter-devel@...r.kernel.org,
        network dev <netdev@...r.kernel.org>
Cc:     Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>, davem@...emloft.net,
        kuba@...nel.org, Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Pravin B Shelar <pshelar@....org>,
        Aaron Conole <aconole@...hat.com>
Subject: [PATCH nf-next 3/6] netfilter: bridge: move pskb_trim_rcsum out of br_nf_check_hbh_len

br_nf_check_hbh_len() is a function to check the Hop-by-hop option
header, and shouldn't do pskb_trim_rcsum() there. This patch is to
pass pkt_len out to br_validate_ipv6() and do pskb_trim_rcsum()
after calling br_validate_ipv6() instead.

Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/bridge/br_netfilter_ipv6.c | 33 ++++++++++++++-------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/net/bridge/br_netfilter_ipv6.c b/net/bridge/br_netfilter_ipv6.c
index 50f564c33551..07289e4f3213 100644
--- a/net/bridge/br_netfilter_ipv6.c
+++ b/net/bridge/br_netfilter_ipv6.c
@@ -43,11 +43,11 @@
 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff
  * anyway
  */
-static int br_nf_check_hbh_len(struct sk_buff *skb)
+static int br_nf_check_hbh_len(struct sk_buff *skb, u32 *plen)
 {
 	int len, off = sizeof(struct ipv6hdr);
 	unsigned char *nh;
-	u32 pkt_len;
+	u32 pkt_len = 0;
 
 	if (!pskb_may_pull(skb, off + 8))
 		return -1;
@@ -83,10 +83,6 @@ static int br_nf_check_hbh_len(struct sk_buff *skb)
 				return -1;
 			if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 				return -1;
-			if (pskb_trim_rcsum(skb,
-					    pkt_len + sizeof(struct ipv6hdr)))
-				return -1;
-			nh = skb_network_header(skb);
 		}
 		off += optlen;
 		len -= optlen;
@@ -94,6 +90,8 @@ static int br_nf_check_hbh_len(struct sk_buff *skb)
 	if (len)
 		return -1;
 
+	if (pkt_len)
+		*plen = pkt_len;
 	return 0;
 }
 
@@ -116,22 +114,19 @@ int br_validate_ipv6(struct net *net, struct sk_buff *skb)
 		goto inhdr_error;
 
 	pkt_len = ntohs(hdr->payload_len);
+	if (hdr->nexthdr == NEXTHDR_HOP && br_nf_check_hbh_len(skb, &pkt_len))
+		goto drop;
 
-	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
-		if (pkt_len + ip6h_len > skb->len) {
-			__IP6_INC_STATS(net, idev,
-					IPSTATS_MIB_INTRUNCATEDPKTS);
-			goto drop;
-		}
-		if (pskb_trim_rcsum(skb, pkt_len + ip6h_len)) {
-			__IP6_INC_STATS(net, idev,
-					IPSTATS_MIB_INDISCARDS);
-			goto drop;
-		}
-		hdr = ipv6_hdr(skb);
+	if (pkt_len + ip6h_len > skb->len) {
+		__IP6_INC_STATS(net, idev,
+				IPSTATS_MIB_INTRUNCATEDPKTS);
+		goto drop;
 	}
-	if (hdr->nexthdr == NEXTHDR_HOP && br_nf_check_hbh_len(skb))
+	if (pskb_trim_rcsum(skb, pkt_len + ip6h_len)) {
+		__IP6_INC_STATS(net, idev,
+				IPSTATS_MIB_INDISCARDS);
 		goto drop;
+	}
 
 	memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
 	/* No IP options in IPv6 header; however it should be
-- 
2.39.1