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

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Date:   Thu, 17 Nov 2022 02:27:18 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Hangbin Liu <liuhangbin@...il.com>,
        Jay Vosburgh <jay.vosburgh@...onical.com>
Cc:     "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        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 11/17/22 00:34, Hangbin Liu wrote:
> On Wed, Nov 16, 2022 at 08:29:58PM -0800, Jay Vosburgh wrote:
>>> #if IS_ENABLED(CONFIG_IPV6)
>>> -	} else if (is_ipv6) {
>>> +	} else if (is_ipv6 && skb_header_pointer(skb, 0, sizeof(ip6_hdr), &ip6_hdr)) {
>>> 		return bond_na_rcv(skb, bond, slave);
>>> #endif
>>> 	} else {
>>>
>>> What do you think?
>> 	I don't see how this solves the icmp6_hdr() / ipv6_hdr() problem
>> in bond_na_rcv(); skb_header_pointer() doesn't do a pull, it just copies
>> into the supplied struct (if necessary).
> Hmm... Maybe I didn't get what you and Eric means. If we can copy the
> supplied buffer success, doesn't this make sure IPv6 header is in skb?


Please try :


diff --git a/drivers/net/bonding/bond_main.c 
b/drivers/net/bonding/bond_main.c
index 
1cd4e71916f80876ca56eb778f8423aa04c80684..c4bdc707c62c4a29c3e16ec4ad523feae00447cb 
100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3224,16 +3224,24 @@ 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;
+       struct {
+               struct ipv6hdr ip6;
+               struct icmp6hdr icmp6;
+       } *combined, _combined;

         if (skb->pkt_type == PACKET_OTHERHOST ||
-           skb->pkt_type == PACKET_LOOPBACK ||
-           hdr->icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT)
+           skb->pkt_type == PACKET_LOOPBACK)
+               goto out;
+
+       combined = skb_header_pointer(skb, 0, sizeof(_combined), 
&_combined);
+       if (!combined ||
+           combined->ip6.nexthdr != NEXTHDR_ICMP ||
+           combined->icmp6.icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT)
                 goto out;

-       saddr = &ipv6_hdr(skb)->saddr;
-       daddr = &ipv6_hdr(skb)->daddr;
+       saddr = &combined->ip6.saddr;
+       daddr = &combined->ip6.daddr;

         slave_dbg(bond->dev, slave->dev, "%s: %s/%d av %d sv %d sip 
%pI6c tip %pI6c\n",
                   __func__, slave->dev->name, bond_slave_state(slave),