netdev - Re: [PATCHv3 net] bonding: fix ICMPv6 header handling when receiving IPv6 messages

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Message-ID: <49594248-1fd7-23e2-1f17-9af896cd25b0@gmail.com>
Date:   Wed, 9 Nov 2022 12:17:10 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Hangbin Liu <liuhangbin@...il.com>, netdev@...r.kernel.org,
        edumazet@...gle.com
Cc:     Jay Vosburgh <j.vosburgh@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jonathan Toppins <jtoppins@...hat.com>,
        Paolo Abeni <pabeni@...hat.com>,
        David Ahern <dsahern@...il.com>, Liang Li <liali@...hat.com>,
        David Ahern <dsahern@...nel.org>
Subject: Re: [PATCHv3 net] bonding: fix ICMPv6 header handling when receiving
 IPv6 messages


On 11/8/22 17:40, Hangbin Liu wrote:
> Currently, we get icmp6hdr via function icmp6_hdr(), which needs the skb
> transport header to be set first. But there is no rule to ask driver set
> transport header before netif_receive_skb() and bond_handle_frame(). So
> we will not able to get correct icmp6hdr on some drivers.
>
> Fix this by checking the skb length manually and getting icmp6 header based
> on the IPv6 header offset.
>
> Reported-by: Liang Li <liali@...hat.com>
> Fixes: 4e24be018eb9 ("bonding: add new parameter ns_targets")
> Acked-by: Jonathan Toppins <jtoppins@...hat.com>
> Reviewed-by: David Ahern <dsahern@...nel.org>
> Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
> ---
> v3: fix _hdr parameter warning reported by kernel test robot
> v2: use skb_header_pointer() to get icmp6hdr as Jay suggested.
> ---
>   drivers/net/bonding/bond_main.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index e84c49bf4d0c..2c6356232668 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -3231,12 +3231,17 @@ static int bond_na_rcv(const struct sk_buff *skb, struct bonding *bond,
>   		       struct slave *slave)
>   {
>   	struct slave *curr_active_slave, *curr_arp_slave;
> -	struct icmp6hdr *hdr = icmp6_hdr(skb);
>   	struct in6_addr *saddr, *daddr;
> +	const struct icmp6hdr *hdr;
> +	struct icmp6hdr _hdr;
>   
>   	if (skb->pkt_type == PACKET_OTHERHOST ||
>   	    skb->pkt_type == PACKET_LOOPBACK ||
> -	    hdr->icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT)
> +	    ipv6_hdr(skb)->nexthdr != NEXTHDR_ICMP)


What makes sure IPv6 header is in skb->head (linear part of the skb) ?


> +		goto out;
> +
> +	hdr = skb_header_pointer(skb, sizeof(struct ipv6hdr), sizeof(_hdr), &_hdr);
> +	if (!hdr || hdr->icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT)
>   		goto out;
>   
>   	saddr = &ipv6_hdr(skb)->saddr;