[SRU][Trusty][PATCH 1/1] net/bonding: Enforce active-backup policy for IPoIB bonds

[Joseph Salisbury]

From: Mark Bloch <markb at mellanox.com>

BugLink: http://bugs.launchpad.net/bugs/1668042

When using an IPoIB bond currently only active-backup mode is a valid
use case and this commit strengthens it.

Since commit 2ab82852a270 ("net/bonding: Enable bonding to enslave
netdevices not supporting set_mac_address()") was introduced till
4.7-rc1, IPoIB didn't support the set_mac_address ndo, and hence the
fail over mac policy always applied to IPoIB bonds.

With the introduction of commit 492a7e67ff83 ("IB/IPoIB: Allow setting
the device address"), that doesn't hold and practically IPoIB bonds are
broken as of that. To fix it, lets go to fail over mac if the device
doesn't support the ndo OR this is IPoIB device.

As a by-product, this commit also prevents a stack corruption which
occurred when trying to copy 20 bytes (IPoIB) device address
to a sockaddr struct that has only 16 bytes of storage.

Signed-off-by: Mark Bloch <markb at mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz at mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm at mellanox.com>
Acked-by: Andy Gospodarek <gospo at cumulusnetworks.com>
Signed-off-by: Jay Vosburgh <jay.vosburgh at canonical.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(backported from commit 1533e77315220dc1d5ec3bd6d9fe32e2aa0a74c0)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
---
 drivers/net/bonding/bond_main.c | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 5ca2b11..b806cd5 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1338,16 +1338,27 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 		goto err_undo_flags;
 	}
 
-	if (slave_ops->ndo_set_mac_address == NULL) {
-		if (!bond_has_slaves(bond)) {
-			pr_warning("%s: Warning: The first slave device specified does not support setting the MAC address. Setting fail_over_mac to active.",
-				   bond_dev->name);
-			bond->params.fail_over_mac = BOND_FOM_ACTIVE;
-		} else if (bond->params.fail_over_mac != BOND_FOM_ACTIVE) {
-			pr_err("%s: Error: The slave device specified does not support setting the MAC address, but fail_over_mac is not set to active.\n",
-			       bond_dev->name);
-			res = -EOPNOTSUPP;
-			goto err_undo_flags;
+	if (slave_dev->type == ARPHRD_INFINIBAND &&
+	    bond->params.mode != BOND_MODE_ACTIVEBACKUP) {
+		netdev_warn(bond_dev, "Type (%d) supports only active-backup mode\n",
+			    slave_dev->type);
+		res = -EOPNOTSUPP;
+		goto err_undo_flags;
+	}
+
+	if (!slave_ops->ndo_set_mac_address ||
+	    slave_dev->type == ARPHRD_INFINIBAND) {
+		netdev_warn(bond_dev, "The slave device specified does not support setting the MAC address\n");
+		if (bond->params.mode == BOND_MODE_ACTIVEBACKUP &&
+		    bond->params.fail_over_mac != BOND_FOM_ACTIVE) {
+			if (!bond_has_slaves(bond)) {
+				bond->params.fail_over_mac = BOND_FOM_ACTIVE;
+				netdev_warn(bond_dev, "Setting fail_over_mac to active for active-backup mode\n");
+			} else {
+				netdev_err(bond_dev, "The slave device specified does not support setting the MAC address, but fail_over_mac is not set to active\n");
+				res = -EOPNOTSUPP;
+				goto err_undo_flags;
+			}
 		}
 	}
 
-- 
2.7.4