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Message-ID: <eb4c1dfe-d7c6-3011-e550-7498ccd023d7@chinatelecom.cn>
Date: Mon, 20 Dec 2021 09:57:03 +0800
From: 孙守鑫 <sunshouxin@...natelecom.cn>
To: Eric Dumazet <eric.dumazet@...il.com>, j.vosburgh@...il.com,
vfalico@...il.com, andy@...yhouse.net, davem@...emloft.net,
kuba@...nel.org
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
huyd12@...natelecom.cn
Subject: Re: [PATCH V2] net: bonding: Add support for IPV6 ns/na
在 2021/12/14 16:05, Eric Dumazet 写道:
>
> On 12/10/21 5:08 AM, Sun Shouxin wrote:
>> Since ipv6 neighbor solicitation and advertisement messages
>> isn't handled gracefully in bonding6 driver, we can see packet
>> drop due to inconsistency bewteen mac address in the option
>> message and source MAC .
>>
>> Another examples is ipv6 neighbor solicitation and advertisement
>> messages from VM via tap attached to host brighe, the src mac
>> mighe be changed through balance-alb mode, but it is not synced
>> with Link-layer address in the option message.
>>
>> The patch implements bond6's tx handle for ipv6 neighbor
>> solicitation and advertisement messages.
>>
>> Border-Leaf
>> / \
>> / \
>> Tunnel1 Tunnel2
>> / \
>> / \
>> Leaf-1--Tunnel3--Leaf-2
>> \ /
>> \ /
>> \ /
>> \ /
>> NIC1 NIC2
>> \ /
>> server
>>
>> We can see in our lab the Border-Leaf receives occasionally
>> a NA packet which is assigned to NIC1 mac in ND/NS option
>> message, but actaully send out via NIC2 mac due to tx-alb,
>> as a result, it will cause inconsistency between MAC table
>> and ND Table in Border-Leaf, i.e, NIC1 = Tunnel2 in ND table
>> and NIC1 = Tunnel1 in mac table.
>>
>> And then, Border-Leaf starts to forward packet destinated
>> to the Server, it will only check the ND table entry in some
>> switch to encapsulate the destination MAC of the message as
>> NIC1 MAC, and then send it out from Tunnel2 by ND table.
>> Then, Leaf-2 receives the packet, it notices the destination
>> MAC of message is NIC1 MAC and should forword it to Tunne1
>> by Tunnel3.
>>
>> However, this traffic forward will be failure due to split
>> horizon of VxLAN tunnels.
>>
>> Suggested-by: Hu Yadi <huyd12@...natelecom.cn>
>> Signed-off-by: Sun Shouxin <sunshouxin@...natelecom.cn>
>> ---
>> drivers/net/bonding/bond_alb.c | 131
>> +++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 131 insertions(+)
>>
>> diff --git a/drivers/net/bonding/bond_alb.c
>> b/drivers/net/bonding/bond_alb.c
>> index 533e476..afa386b 100644
>> --- a/drivers/net/bonding/bond_alb.c
>> +++ b/drivers/net/bonding/bond_alb.c
>> @@ -22,6 +22,7 @@
>> #include <asm/byteorder.h>
>> #include <net/bonding.h>
>> #include <net/bond_alb.h>
>> +#include <net/ndisc.h>
>> static const u8 mac_v6_allmcast[ETH_ALEN + 2] __long_aligned = {
>> 0x33, 0x33, 0x00, 0x00, 0x00, 0x01
>> @@ -1269,6 +1270,119 @@ static int alb_set_mac_address(struct bonding
>> *bond, void *addr)
>> return res;
>> }
>> +/*determine if the packet is NA or NS*/
>> +static bool alb_determine_nd(struct icmp6hdr *hdr)
>> +{
>> + if (hdr->icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT ||
>> + hdr->icmp6_type == NDISC_NEIGHBOUR_SOLICITATION) {
>> + return true;
>> + }
>> +
>> + return false;
>> +}
>> +
>> +static void alb_change_nd_option(struct sk_buff *skb, void *data)
>> +{
>> + struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
>> + struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)msg->opt;
>> + struct net_device *dev = skb->dev;
>> + struct icmp6hdr *icmp6h = icmp6_hdr(skb);
>> + struct ipv6hdr *ip6hdr = ipv6_hdr(skb);
>> + u8 *lladdr = NULL;
>> + u32 ndoptlen = skb_tail_pointer(skb) - (skb_transport_header(skb) +
>> + offsetof(struct nd_msg, opt));
>> +
>> + while (ndoptlen) {
>> + int l;
>> +
>> + switch (nd_opt->nd_opt_type) {
>> + case ND_OPT_SOURCE_LL_ADDR:
>> + case ND_OPT_TARGET_LL_ADDR:
>> + lladdr = ndisc_opt_addr_data(nd_opt, dev);
>> + break;
>> +
>> + default:
>> + lladdr = NULL;
>> + break;
>> + }
>> +
>> + l = nd_opt->nd_opt_len << 3;
>> +
>> + if (ndoptlen < l || l == 0)
>> + return;
>> +
>> + if (lladdr) {
>> + memcpy(lladdr, data, dev->addr_len);
>
> I am not sure it is allowed to change skb content without
>
> making sure skb ->head is private.
>
> (Think of tcpdump -i slaveX : we want to see the packet content before
> your change)
>
> I would think skb_cow_head() or something similar is needed.
>
> This is tricky of course, since all cached pointers (icmp6h, ip6hdr,
> msg, nd_opt)
>
> would need to be fetched again, since skb->head/data might be changed
>
> by skb_cow_head().
The tcpdump should show the last packet which sent off from NIC in the end.
could you light me up specific conditions?
>
>
>
>
>
>> + icmp6h->icmp6_cksum = 0;
>> +
>> + icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6hdr->saddr,
>> + &ip6hdr->daddr,
>> + ntohs(ip6hdr->payload_len),
>> + IPPROTO_ICMPV6,
>> + csum_partial(icmp6h,
>> + ntohs(ip6hdr->payload_len), 0));
>> + }
>> + ndoptlen -= l;
>> + nd_opt = ((void *)nd_opt) + l;
>> + }
>> +}
>> +
>> +static u8 *alb_get_lladdr(struct sk_buff *skb)
>> +{
>> + struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
>> + struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)msg->opt;
>> + struct net_device *dev = skb->dev;
>> + u8 *lladdr = NULL;
>> + u32 ndoptlen = skb_tail_pointer(skb) - (skb_transport_header(skb) +
>> + offsetof(struct nd_msg, opt));
>> +
>> + while (ndoptlen) {
>> + int l;
>> +
>> + switch (nd_opt->nd_opt_type) {
>> + case ND_OPT_SOURCE_LL_ADDR:
>> + case ND_OPT_TARGET_LL_ADDR:
>> + lladdr = ndisc_opt_addr_data(nd_opt, dev);
>> + break;
>> +
>> + default:
>> + break;
>> + }
>> +
>> + l = nd_opt->nd_opt_len << 3;
>> +
>> + if (ndoptlen < l || l == 0)
>> + return lladdr;
>
> return NULL ?
>
> (or risk out-of-bound access ?)
Thanks your comment, I'll adjust it and send out V4 soon.
>
>> +
>> + if (lladdr)
>> + return lladdr;
>> +
>> + ndoptlen -= l;
>> + nd_opt = ((void *)nd_opt) + l;
>> + }
>> +
>> + return lladdr;
>> +}
>> +
>> +static void alb_set_nd_option(struct sk_buff *skb, struct bonding
>> *bond,
>> + struct slave *tx_slave)
>> +{
>> + struct ipv6hdr *ip6hdr;
>> + struct icmp6hdr *hdr = NULL;
>> +
>> + if (skb->protocol == htons(ETH_P_IPV6)) {
>> + if (tx_slave && tx_slave !=
>> + rcu_access_pointer(bond->curr_active_slave)) {
>> + ip6hdr = ipv6_hdr(skb);
>> + if (ip6hdr->nexthdr == IPPROTO_ICMPV6) {
>> + hdr = icmp6_hdr(skb);
>> + if (alb_determine_nd(hdr))
>> + alb_change_nd_option(skb, tx_slave->dev->dev_addr);
>> + }
>> + }
>> + }
>> +}
>> +
>> /************************ exported alb functions
>> ************************/
>> int bond_alb_initialize(struct bonding *bond, int rlb_enabled)
>> @@ -1415,6 +1529,7 @@ struct slave *bond_xmit_alb_slave_get(struct
>> bonding *bond,
>> }
>> case ETH_P_IPV6: {
>> const struct ipv6hdr *ip6hdr;
>> + struct icmp6hdr *hdr = NULL;
>> /* IPv6 doesn't really use broadcast mac address, but leave
>> * that here just in case.
>> @@ -1446,6 +1561,21 @@ struct slave *bond_xmit_alb_slave_get(struct
>> bonding *bond,
>> break;
>> }
>> + if (ip6hdr->nexthdr == IPPROTO_ICMPV6) {
>> + hdr = icmp6_hdr(skb);
>> + if (alb_determine_nd(hdr)) {
>> + u8 *lladdr = NULL;
>> +
>> + lladdr = alb_get_lladdr(skb);
>> + if (lladdr) {
>> + if (!bond_slave_has_mac_rx(bond, lladdr)) {
>> + do_tx_balance = false;
>> + break;
>> + }
>> + }
>> + }
>> + }
>> +
>> hash_start = (char *)&ip6hdr->daddr;
>> hash_size = sizeof(ip6hdr->daddr);
>> break;
>> @@ -1489,6 +1619,7 @@ netdev_tx_t bond_alb_xmit(struct sk_buff *skb,
>> struct net_device *bond_dev)
>> struct slave *tx_slave = NULL;
>> tx_slave = bond_xmit_alb_slave_get(bond, skb);
>> + alb_set_nd_option(skb, bond, tx_slave);
>> return bond_do_alb_xmit(skb, bond, tx_slave);
>> }
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