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

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Message-ID: <f7ty1o84dlh.fsf@redhat.com>
Date:   Tue, 07 Mar 2023 13:32:10 -0500
From:   Aaron Conole <aconole@...hat.com>
To:     Xin Long <lucien.xin@...il.com>
Cc:     netfilter-devel@...r.kernel.org,
        network dev <netdev@...r.kernel.org>,
        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>
Subject: Re: [PATCH nf-next 3/6] netfilter: bridge: move pskb_trim_rcsum out
 of br_nf_check_hbh_len

Xin Long <lucien.xin@...il.com> writes:

> 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>
> ---

Reviewed-by: Aaron Conole <aconole@...hat.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