netdev - Re: [PATCH net] bonding: fix lladdr finding and confirmation

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Date:   Sun, 28 Aug 2022 16:20:43 -0700
From:   Jay Vosburgh <jay.vosburgh@...onical.com>
To:     Hangbin Liu <liuhangbin@...il.com>
cc:     netdev@...r.kernel.org, Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>,
        "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>, LiLiang <liali@...hat.com>
Subject: Re: [PATCH net] bonding: fix lladdr finding and confirmation

Hangbin Liu <liuhangbin@...il.com> wrote:

>There are 3 issues when setting lladdr as bonding IPv6 target
>
>1. On the send side. When ns_ip6_target was set, the ipv6_dev_get_saddr()
>   will be called to get available src addr and send IPv6 neighbor solicit
>   message.
>
>   If the target is global address, ipv6_dev_get_saddr() will get any
>   available src address. But if the target is link local address,
>   ipv6_dev_get_saddr() will only get available address from out interace,

	Should this be "our interface"?

>   i.e. the corresponding bond interface.
>
>   But before bond interface up, all the address is tentative, while
>   ipv6_dev_get_saddr() will ignore tentative address. This makes we can't
>   find available link local src address, then bond_ns_send() will not be
>   called and no NS message was sent. Thus no NA message received and bond
>   interface will keep in down state.
>
>   Fix this by sending NS with unspecified address if there is no available
>   source address.
>
>2. On the receive side. The slave was set down before enslave to bond.
>   This makes slaves remove mcast address 33:33:00:00:00:01( The IPv6
>   maddr ff02::1 is kept even when the interface down). When bond set
>   slave up, the ipv6_mc_up() was not called due to commit c2edacf80e15
>   ("bonding / ipv6: no addrconf for slaves separately from master").
>   This makes the slave interface never add the all node mcast address
>   33:33:00:00:00:01. So there is no way to accept unsolicited NA with
>   dest ff02::1.
>
>   Fix this by adding all node mcast address 33:33:00:00:00:01 back when
>   the slave interface up.
>
>3. On the validating side. The NA message with all-nodes multicast dest
>   address should also be valid.
>
>   Also rename bond_validate_ns() to bond_validate_na().

	I'm not exactly sure which change matches which of the three
above fixes; should this be three separate patches?

>Reported-by: LiLiang <liali@...hat.com>
>Fixes: 5e1eeef69c0f ("bonding: NS target should accept link local address")

	Is this fixes tag correct for all the fixes?  Number 2 cites a
different commit (c2edacf80e15).  Again, should these be three separate
patches?

>Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
>---
> drivers/net/bonding/bond_main.c | 20 +++++++++++++++-----
> net/ipv6/addrconf.c             |  7 +++++--
> 2 files changed, 20 insertions(+), 7 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index 2f4da2c13c0a..5c2febe94428 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -3167,6 +3167,9 @@ static void bond_ns_send_all(struct bonding *bond, struct slave *slave)
> found:
> 		if (!ipv6_dev_get_saddr(dev_net(dst->dev), dst->dev, &targets[i], 0, &saddr))
> 			bond_ns_send(slave, &targets[i], &saddr, tags);
>+		else
>+			bond_ns_send(slave, &targets[i], &in6addr_any, tags);
>+
> 		dst_release(dst);
> 		kfree(tags);
> 	}
>@@ -3198,12 +3201,19 @@ static bool bond_has_this_ip6(struct bonding *bond, struct in6_addr *addr)
> 	return ret;
> }
> 
>-static void bond_validate_ns(struct bonding *bond, struct slave *slave,
>+static void bond_validate_na(struct bonding *bond, struct slave *slave,
> 			     struct in6_addr *saddr, struct in6_addr *daddr)
> {
> 	int i;
> 
>-	if (ipv6_addr_any(saddr) || !bond_has_this_ip6(bond, daddr)) {
>+	/* Ignore NAs that:
>+	 * 1. Source address is unspecified address.
>+	 * 2. Dest address is neither all-nodes multicast address nor
>+	 *    exist on bond interface.
>+	 */
>+	if (ipv6_addr_any(saddr) ||
>+	    (!ipv6_addr_equal(daddr, &in6addr_linklocal_allnodes) &&
>+	     !bond_has_this_ip6(bond, daddr))) {
> 		slave_dbg(bond->dev, slave->dev, "%s: sip %pI6c tip %pI6c not found\n",
> 			  __func__, saddr, daddr);
> 		return;
>@@ -3246,14 +3256,14 @@ static int bond_na_rcv(const struct sk_buff *skb, struct bonding *bond,
> 	 * see bond_arp_rcv().
> 	 */
> 	if (bond_is_active_slave(slave))
>-		bond_validate_ns(bond, slave, saddr, daddr);
>+		bond_validate_na(bond, slave, saddr, daddr);
> 	else if (curr_active_slave &&
> 		 time_after(slave_last_rx(bond, curr_active_slave),
> 			    curr_active_slave->last_link_up))
>-		bond_validate_ns(bond, slave, saddr, daddr);
>+		bond_validate_na(bond, slave, saddr, daddr);
> 	else if (curr_arp_slave &&
> 		 bond_time_in_interval(bond, slave_last_tx(curr_arp_slave), 1))
>-		bond_validate_ns(bond, slave, saddr, daddr);
>+		bond_validate_na(bond, slave, saddr, daddr);

	Is this logic correct?  If I'm not mistaken, there are two
receive cases:

	1- We receive a reply (Neighbor Advertisement) to our request
(Neighbor Solicitation).

	2- We receive a copy of our request (NS), which passed through
the switch and was received by another interface of the bond.

	For the ARP monitor implementation, in the second case, the
source and target IP addresses are swapped for the validation.

	Is such a swap necessary for the NS/NA monitor implementation?
I would expect this to be in the second block of the if (inside the
"else if (curr_active_slave &&" block).

	-J

> out:
> 	return RX_HANDLER_ANOTHER;
>diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
>index e15f64f22fa8..77750b6327e7 100644
>--- a/net/ipv6/addrconf.c
>+++ b/net/ipv6/addrconf.c
>@@ -3557,11 +3557,14 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
> 		fallthrough;
> 	case NETDEV_UP:
> 	case NETDEV_CHANGE:
>-		if (dev->flags & IFF_SLAVE)
>+		if (idev && idev->cnf.disable_ipv6)
> 			break;
> 
>-		if (idev && idev->cnf.disable_ipv6)
>+		if (dev->flags & IFF_SLAVE) {
>+			if (event == NETDEV_UP && !IS_ERR_OR_NULL(idev))
>+				ipv6_mc_up(idev);
> 			break;
>+		}
> 
> 		if (event == NETDEV_UP) {
> 			/* restore routes for permanent addresses */
>-- 
>2.37.1
>

---
	-Jay Vosburgh, jay.vosburgh@...onical.com