Messages in this thread | | | Date | Mon, 20 Dec 2021 09:57:03 +0800 | Subject | Re: [PATCH V2] net: bonding: Add support for IPV6 ns/na | From | 孙守鑫 <> |
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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@chinatelecom.cn> >> Signed-off-by: Sun Shouxin <sunshouxin@chinatelecom.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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