Re: [PATCH V2] net: bonding: Add support for IPV6 ns/na
From: Eric Dumazet
Date: Tue Dec 14 2021 - 03:05:27 EST
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@xxxxxxxxxxxxxxx>
Signed-off-by: Sun Shouxin <sunshouxin@xxxxxxxxxxxxxxx>
---
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().
+ 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 ?)
+
+ 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);
}