macvlan: validate setting of multiple remote source MAC addresses

Remote source MAC addresses can be set on a 'source mode' macvlan
interface via the IFLA_MACVLAN_MACADDR_DATA attribute. This commit
tightens the validation of these MAC addresses to match the validation
already performed when setting or adding a single MAC address via the
IFLA_MACVLAN_MACADDR attribute.

iproute2 uses IFLA_MACVLAN_MACADDR_DATA for its 'macvlan macaddr set'
command, and IFLA_MACVLAN_MACADDR for its 'macvlan macaddr add' command,
which demonstrates the inconsistent behaviour that this commit
addresses:

 # ip link add link eth0 name macvlan0 type macvlan mode source
 # ip link set link dev macvlan0 type macvlan macaddr add 01:00:00:00:00:00
 RTNETLINK answers: Cannot assign requested address
 # ip link set link dev macvlan0 type macvlan macaddr set 01:00:00:00:00:00
 # ip -d link show macvlan0
 5: macvlan0@eth0: <BROADCAST,MULTICAST,DYNAMIC,UP,LOWER_UP> mtu 1500 ...
     link/ether 2e:ac:fd:2d:69:f8 brd ff:ff:ff:ff:ff:ff promiscuity 0
     macvlan mode source remotes (1) 01:00:00:00:00:00 numtxqueues 1 ...

With this change, the 'set' command will (rightly) fail in the same way
as the 'add' command.
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macvlan.c

@@ -1269,6 +1269,9 @@ static void macvlan_port_destroy(struct net_device *dev)
 static int macvlan_validate(struct nlattr *tb[], struct nlattr *data[],
 			    struct netlink_ext_ack *extack)
 {
+	struct nlattr *nla, *head;
+	int rem, len;
+
 	if (tb[IFLA_ADDRESS]) {
 		if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
 			return -EINVAL;
@@ -1316,6 +1319,20 @@ static int macvlan_validate(struct nlattr *tb[], struct nlattr *data[],
 			return -EADDRNOTAVAIL;
 	}
 
+	if (data[IFLA_MACVLAN_MACADDR_DATA]) {
+		head = nla_data(data[IFLA_MACVLAN_MACADDR_DATA]);
+		len = nla_len(data[IFLA_MACVLAN_MACADDR_DATA]);
+
+		nla_for_each_attr(nla, head, len, rem) {
+			if (nla_type(nla) != IFLA_MACVLAN_MACADDR ||
+			    nla_len(nla) != ETH_ALEN)
+				return -EINVAL;
+
+			if (!is_valid_ether_addr(nla_data(nla)))
+				return -EADDRNOTAVAIL;
+		}
+	}
+
 	if (data[IFLA_MACVLAN_MACADDR_COUNT])
 		return -EINVAL;
 
@@ -1372,10 +1389,6 @@ static int macvlan_changelink_sources(struct macvlan_dev *vlan, u32 mode,
 		len = nla_len(data[IFLA_MACVLAN_MACADDR_DATA]);
 
 		nla_for_each_attr(nla, head, len, rem) {
-			if (nla_type(nla) != IFLA_MACVLAN_MACADDR ||
-			    nla_len(nla) != ETH_ALEN)
-				continue;
-
 			addr = nla_data(nla);
 			ret = macvlan_hash_add_source(vlan, addr);
 			if (ret)