Merge branch 'bridge-add-mac-authentication-bypass-mab-support'

Ido Schimmel says:

====================
bridge: Add MAC Authentication Bypass (MAB) support

Patch #1 adds MAB support in the bridge driver. See the commit message
for motivation, design choices and implementation details.

Patch #2 adds corresponding test cases.

Follow-up patchsets will add offload support in mlxsw and mv88e6xxx.
====================

Link: https://lore.kernel.org/r/20221101193922.2125323-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/linux/if_bridge.h

@@ -59,6 +59,7 @@ struct br_ip_list {
 #define BR_MRP_LOST_IN_CONT	BIT(19)
 #define BR_TX_FWD_OFFLOAD	BIT(20)
 #define BR_PORT_LOCKED		BIT(21)
+#define BR_PORT_MAB		BIT(22)
 
 #define BR_DEFAULT_AGEING_TIME	(300 * HZ)
 

include/uapi/linux/if_link.h

@@ -561,6 +561,7 @@ enum {
 	IFLA_BRPORT_MCAST_EHT_HOSTS_LIMIT,
 	IFLA_BRPORT_MCAST_EHT_HOSTS_CNT,
 	IFLA_BRPORT_LOCKED,
+	IFLA_BRPORT_MAB,
 	__IFLA_BRPORT_MAX
 };
 #define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1)

include/uapi/linux/neighbour.h

@@ -52,7 +52,8 @@ enum {
 #define NTF_STICKY	(1 << 6)
 #define NTF_ROUTER	(1 << 7)
 /* Extended flags under NDA_FLAGS_EXT: */
-#define NTF_EXT_MANAGED	(1 << 0)
+#define NTF_EXT_MANAGED		(1 << 0)
+#define NTF_EXT_LOCKED		(1 << 1)
 
 /*
  *	Neighbor Cache Entry States.
@@ -86,6 +87,11 @@ enum {
  * NTF_EXT_MANAGED flagged neigbor entries are managed by the kernel on behalf
  * of a user space control plane, and automatically refreshed so that (if
  * possible) they remain in NUD_REACHABLE state.
+ *
+ * NTF_EXT_LOCKED flagged bridge FDB entries are entries generated by the
+ * bridge in response to a host trying to communicate via a locked bridge port
+ * with MAB enabled. Their purpose is to notify user space that a host requires
+ * authentication.
  */
 
 struct nda_cacheinfo {

net/bridge/br_fdb.c

@@ -105,6 +105,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
 	struct nda_cacheinfo ci;
 	struct nlmsghdr *nlh;
 	struct ndmsg *ndm;
+	u32 ext_flags = 0;
 
 	nlh = nlmsg_put(skb, portid, seq, type, sizeof(*ndm), flags);
 	if (nlh == NULL)
@@ -125,11 +126,16 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
 		ndm->ndm_flags |= NTF_EXT_LEARNED;
 	if (test_bit(BR_FDB_STICKY, &fdb->flags))
 		ndm->ndm_flags |= NTF_STICKY;
+	if (test_bit(BR_FDB_LOCKED, &fdb->flags))
+		ext_flags |= NTF_EXT_LOCKED;
 
 	if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->key.addr))
 		goto nla_put_failure;
 	if (nla_put_u32(skb, NDA_MASTER, br->dev->ifindex))
 		goto nla_put_failure;
+	if (nla_put_u32(skb, NDA_FLAGS_EXT, ext_flags))
+		goto nla_put_failure;
+
 	ci.ndm_used	 = jiffies_to_clock_t(now - fdb->used);
 	ci.ndm_confirmed = 0;
 	ci.ndm_updated	 = jiffies_to_clock_t(now - fdb->updated);
@@ -171,6 +177,7 @@ static inline size_t fdb_nlmsg_size(void)
 	return NLMSG_ALIGN(sizeof(struct ndmsg))
 		+ nla_total_size(ETH_ALEN) /* NDA_LLADDR */
 		+ nla_total_size(sizeof(u32)) /* NDA_MASTER */
+		+ nla_total_size(sizeof(u32)) /* NDA_FLAGS_EXT */
 		+ nla_total_size(sizeof(u16)) /* NDA_VLAN */
 		+ nla_total_size(sizeof(struct nda_cacheinfo))
 		+ nla_total_size(0) /* NDA_FDB_EXT_ATTRS */
@@ -879,6 +886,11 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 						      &fdb->flags)))
 					clear_bit(BR_FDB_ADDED_BY_EXT_LEARN,
 						  &fdb->flags);
+				/* Clear locked flag when roaming to an
+				 * unlocked port.
+				 */
+				if (unlikely(test_bit(BR_FDB_LOCKED, &fdb->flags)))
+					clear_bit(BR_FDB_LOCKED, &fdb->flags);
 			}
 
 			if (unlikely(test_bit(BR_FDB_ADDED_BY_USER, &flags)))
@@ -1082,6 +1094,9 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 		modified = true;
 	}
 
+	if (test_and_clear_bit(BR_FDB_LOCKED, &fdb->flags))
+		modified = true;
+
 	if (fdb_handle_notify(fdb, notify))
 		modified = true;
 
@@ -1150,6 +1165,7 @@ int br_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
 	struct net_bridge_port *p = NULL;
 	struct net_bridge_vlan *v;
 	struct net_bridge *br = NULL;
+	u32 ext_flags = 0;
 	int err = 0;
 
 	trace_br_fdb_add(ndm, dev, addr, vid, nlh_flags);
@@ -1178,6 +1194,14 @@ int br_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
 		vg = nbp_vlan_group(p);
 	}
 
+	if (tb[NDA_FLAGS_EXT])
+		ext_flags = nla_get_u32(tb[NDA_FLAGS_EXT]);
+
+	if (ext_flags & NTF_EXT_LOCKED) {
+		NL_SET_ERR_MSG_MOD(extack, "Cannot add FDB entry with \"locked\" flag set");
+		return -EINVAL;
+	}
+
 	if (tb[NDA_FDB_EXT_ATTRS]) {
 		attr = tb[NDA_FDB_EXT_ATTRS];
 		err = nla_parse_nested(nfea_tb, NFEA_MAX, attr,

net/bridge/br_input.c

@@ -109,9 +109,26 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 		struct net_bridge_fdb_entry *fdb_src =
 			br_fdb_find_rcu(br, eth_hdr(skb)->h_source, vid);
 
-		if (!fdb_src || READ_ONCE(fdb_src->dst) != p ||
-		    test_bit(BR_FDB_LOCAL, &fdb_src->flags))
+		if (!fdb_src) {
+			/* FDB miss. Create locked FDB entry if MAB is enabled
+			 * and drop the packet.
+			 */
+			if (p->flags & BR_PORT_MAB)
+				br_fdb_update(br, p, eth_hdr(skb)->h_source,
+					      vid, BIT(BR_FDB_LOCKED));
 			goto drop;
+		} else if (READ_ONCE(fdb_src->dst) != p ||
+			   test_bit(BR_FDB_LOCAL, &fdb_src->flags)) {
+			/* FDB mismatch. Drop the packet without roaming. */
+			goto drop;
+		} else if test_bit(BR_FDB_LOCKED, &fdb_src->flags) {
+			/* FDB match, but entry is locked. Refresh it and drop
+			 * the packet.
+			 */
+			br_fdb_update(br, p, eth_hdr(skb)->h_source, vid,
+				      BIT(BR_FDB_LOCKED));
+			goto drop;
+		}
 	}
 
 	nbp_switchdev_frame_mark(p, skb);

net/bridge/br_netlink.c

@@ -188,6 +188,7 @@ static inline size_t br_port_info_size(void)
 		+ nla_total_size(1)	/* IFLA_BRPORT_NEIGH_SUPPRESS */
 		+ nla_total_size(1)	/* IFLA_BRPORT_ISOLATED */
 		+ nla_total_size(1)	/* IFLA_BRPORT_LOCKED */
+		+ nla_total_size(1)	/* IFLA_BRPORT_MAB */
 		+ nla_total_size(sizeof(struct ifla_bridge_id))	/* IFLA_BRPORT_ROOT_ID */
 		+ nla_total_size(sizeof(struct ifla_bridge_id))	/* IFLA_BRPORT_BRIDGE_ID */
 		+ nla_total_size(sizeof(u16))	/* IFLA_BRPORT_DESIGNATED_PORT */
@@ -274,7 +275,8 @@ static int br_port_fill_attrs(struct sk_buff *skb,
 	    nla_put_u8(skb, IFLA_BRPORT_MRP_IN_OPEN,
 		       !!(p->flags & BR_MRP_LOST_IN_CONT)) ||
 	    nla_put_u8(skb, IFLA_BRPORT_ISOLATED, !!(p->flags & BR_ISOLATED)) ||
-	    nla_put_u8(skb, IFLA_BRPORT_LOCKED, !!(p->flags & BR_PORT_LOCKED)))
+	    nla_put_u8(skb, IFLA_BRPORT_LOCKED, !!(p->flags & BR_PORT_LOCKED)) ||
+	    nla_put_u8(skb, IFLA_BRPORT_MAB, !!(p->flags & BR_PORT_MAB)))
 		return -EMSGSIZE;
 
 	timerval = br_timer_value(&p->message_age_timer);
@@ -876,6 +878,7 @@ static const struct nla_policy br_port_policy[IFLA_BRPORT_MAX + 1] = {
 	[IFLA_BRPORT_NEIGH_SUPPRESS] = { .type = NLA_U8 },
 	[IFLA_BRPORT_ISOLATED]	= { .type = NLA_U8 },
 	[IFLA_BRPORT_LOCKED] = { .type = NLA_U8 },
+	[IFLA_BRPORT_MAB] = { .type = NLA_U8 },
 	[IFLA_BRPORT_BACKUP_PORT] = { .type = NLA_U32 },
 	[IFLA_BRPORT_MCAST_EHT_HOSTS_LIMIT] = { .type = NLA_U32 },
 };
@@ -943,6 +946,22 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[],
 	br_set_port_flag(p, tb, IFLA_BRPORT_NEIGH_SUPPRESS, BR_NEIGH_SUPPRESS);
 	br_set_port_flag(p, tb, IFLA_BRPORT_ISOLATED, BR_ISOLATED);
 	br_set_port_flag(p, tb, IFLA_BRPORT_LOCKED, BR_PORT_LOCKED);
+	br_set_port_flag(p, tb, IFLA_BRPORT_MAB, BR_PORT_MAB);
+
+	if ((p->flags & BR_PORT_MAB) &&
+	    (!(p->flags & BR_PORT_LOCKED) || !(p->flags & BR_LEARNING))) {
+		NL_SET_ERR_MSG(extack, "Bridge port must be locked and have learning enabled when MAB is enabled");
+		p->flags = old_flags;
+		return -EINVAL;
+	} else if (!(p->flags & BR_PORT_MAB) && (old_flags & BR_PORT_MAB)) {
+		struct net_bridge_fdb_flush_desc desc = {
+			.flags = BIT(BR_FDB_LOCKED),
+			.flags_mask = BIT(BR_FDB_LOCKED),
+			.port_ifindex = p->dev->ifindex,
+		};
+
+		br_fdb_flush(p->br, &desc);
+	}
 
 	changed_mask = old_flags ^ p->flags;
 

net/bridge/br_private.h

@@ -251,7 +251,8 @@ enum {
 	BR_FDB_ADDED_BY_EXT_LEARN,
 	BR_FDB_OFFLOADED,
 	BR_FDB_NOTIFY,
-	BR_FDB_NOTIFY_INACTIVE
+	BR_FDB_NOTIFY_INACTIVE,
+	BR_FDB_LOCKED,
 };
 
 struct net_bridge_fdb_key {

net/core/rtnetlink.c

@@ -4051,6 +4051,11 @@ int ndo_dflt_fdb_add(struct ndmsg *ndm,
 		return err;
 	}
 
+	if (tb[NDA_FLAGS_EXT]) {
+		netdev_info(dev, "invalid flags given to default FDB implementation\n");
+		return err;
+	}
+
 	if (vid) {
 		netdev_info(dev, "vlans aren't supported yet for dev_uc|mc_add()\n");
 		return err;

tools/testing/selftests/net/forwarding/bridge_locked_port.sh

@@ -1,7 +1,16 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
-ALL_TESTS="locked_port_ipv4 locked_port_ipv6 locked_port_vlan"
+ALL_TESTS="
+	locked_port_ipv4
+	locked_port_ipv6
+	locked_port_vlan
+	locked_port_mab
+	locked_port_mab_roam
+	locked_port_mab_config
+	locked_port_mab_flush
+"
+
 NUM_NETIFS=4
 CHECK_TC="no"
 source lib.sh
@@ -166,6 +175,150 @@ locked_port_ipv6()
 	log_test "Locked port ipv6"
 }
 
+locked_port_mab()
+{
+	RET=0
+	check_port_mab_support || return 0
+
+	ping_do $h1 192.0.2.2
+	check_err $? "Ping did not work before locking port"
+
+	bridge link set dev $swp1 learning on locked on
+
+	ping_do $h1 192.0.2.2
+	check_fail $? "Ping worked on a locked port without an FDB entry"
+
+	bridge fdb get `mac_get $h1` br br0 vlan 1 &> /dev/null
+	check_fail $? "FDB entry created before enabling MAB"
+
+	bridge link set dev $swp1 learning on locked on mab on
+
+	ping_do $h1 192.0.2.2
+	check_fail $? "Ping worked on MAB enabled port without an FDB entry"
+
+	bridge fdb get `mac_get $h1` br br0 vlan 1 | grep "dev $swp1" | grep -q "locked"
+	check_err $? "Locked FDB entry not created"
+
+	bridge fdb replace `mac_get $h1` dev $swp1 master static
+
+	ping_do $h1 192.0.2.2
+	check_err $? "Ping did not work after replacing FDB entry"
+
+	bridge fdb get `mac_get $h1` br br0 vlan 1 | grep "dev $swp1" | grep -q "locked"
+	check_fail $? "FDB entry marked as locked after replacement"
+
+	bridge fdb del `mac_get $h1` dev $swp1 master
+	bridge link set dev $swp1 learning off locked off mab off
+
+	log_test "Locked port MAB"
+}
+
+# Check that entries cannot roam to a locked port, but that entries can roam
+# to an unlocked port.
+locked_port_mab_roam()
+{
+	local mac=a0:b0:c0:c0:b0:a0
+
+	RET=0
+	check_port_mab_support || return 0
+
+	bridge link set dev $swp1 learning on locked on mab on
+
+	$MZ $h1 -q -c 5 -d 100msec -t udp -a $mac -b rand
+	bridge fdb get $mac br br0 vlan 1 | grep "dev $swp1" | grep -q "locked"
+	check_err $? "No locked entry on first injection"
+
+	$MZ $h2 -q -c 5 -d 100msec -t udp -a $mac -b rand
+	bridge fdb get $mac br br0 vlan 1 | grep -q "dev $swp2"
+	check_err $? "Entry did not roam to an unlocked port"
+
+	bridge fdb get $mac br br0 vlan 1 | grep -q "locked"
+	check_fail $? "Entry roamed with locked flag on"
+
+	$MZ $h1 -q -c 5 -d 100msec -t udp -a $mac -b rand
+	bridge fdb get $mac br br0 vlan 1 | grep -q "dev $swp1"
+	check_fail $? "Entry roamed back to locked port"
+
+	bridge fdb del $mac vlan 1 dev $swp2 master
+	bridge link set dev $swp1 learning off locked off mab off
+
+	log_test "Locked port MAB roam"
+}
+
+# Check that MAB can only be enabled on a port that is both locked and has
+# learning enabled.
+locked_port_mab_config()
+{
+	RET=0
+	check_port_mab_support || return 0
+
+	bridge link set dev $swp1 learning on locked off mab on &> /dev/null
+	check_fail $? "MAB enabled while port is unlocked"
+
+	bridge link set dev $swp1 learning off locked on mab on &> /dev/null
+	check_fail $? "MAB enabled while port has learning disabled"
+
+	bridge link set dev $swp1 learning on locked on mab on
+	check_err $? "Failed to enable MAB when port is locked and has learning enabled"
+
+	bridge link set dev $swp1 learning off locked off mab off
+
+	log_test "Locked port MAB configuration"
+}
+
+# Check that locked FDB entries are flushed from a port when MAB is disabled.
+locked_port_mab_flush()
+{
+	local locked_mac1=00:01:02:03:04:05
+	local unlocked_mac1=00:01:02:03:04:06
+	local locked_mac2=00:01:02:03:04:07
+	local unlocked_mac2=00:01:02:03:04:08
+
+	RET=0
+	check_port_mab_support || return 0
+
+	bridge link set dev $swp1 learning on locked on mab on
+	bridge link set dev $swp2 learning on locked on mab on
+
+	# Create regular and locked FDB entries on each port.
+	bridge fdb add $unlocked_mac1 dev $swp1 vlan 1 master static
+	bridge fdb add $unlocked_mac2 dev $swp2 vlan 1 master static
+
+	$MZ $h1 -q -c 5 -d 100msec -t udp -a $locked_mac1 -b rand
+	bridge fdb get $locked_mac1 br br0 vlan 1 | grep "dev $swp1" | \
+		grep -q "locked"
+	check_err $? "Failed to create locked FDB entry on first port"
+
+	$MZ $h2 -q -c 5 -d 100msec -t udp -a $locked_mac2 -b rand
+	bridge fdb get $locked_mac2 br br0 vlan 1 | grep "dev $swp2" | \
+		grep -q "locked"
+	check_err $? "Failed to create locked FDB entry on second port"
+
+	# Disable MAB on the first port and check that only the first locked
+	# FDB entry was flushed.
+	bridge link set dev $swp1 mab off
+
+	bridge fdb get $unlocked_mac1 br br0 vlan 1 &> /dev/null
+	check_err $? "Regular FDB entry on first port was flushed after disabling MAB"
+
+	bridge fdb get $unlocked_mac2 br br0 vlan 1 &> /dev/null
+	check_err $? "Regular FDB entry on second port was flushed after disabling MAB"
+
+	bridge fdb get $locked_mac1 br br0 vlan 1 &> /dev/null
+	check_fail $? "Locked FDB entry on first port was not flushed after disabling MAB"
+
+	bridge fdb get $locked_mac2 br br0 vlan 1 &> /dev/null
+	check_err $? "Locked FDB entry on second port was flushed after disabling MAB"
+
+	bridge fdb del $unlocked_mac2 dev $swp2 vlan 1 master static
+	bridge fdb del $unlocked_mac1 dev $swp1 vlan 1 master static
+
+	bridge link set dev $swp2 learning on locked off mab off
+	bridge link set dev $swp1 learning off locked off mab off
+
+	log_test "Locked port MAB FDB flush"
+}
+
 trap cleanup EXIT
 
 setup_prepare

tools/testing/selftests/net/forwarding/lib.sh

@@ -137,6 +137,14 @@ check_locked_port_support()
 	fi
 }
 
+check_port_mab_support()
+{
+	if ! bridge -d link show | grep -q "mab"; then
+		echo "SKIP: iproute2 too old; MacAuth feature not supported."
+		return $ksft_skip
+	fi
+}
+
 if [[ "$(id -u)" -ne 0 ]]; then
 	echo "SKIP: need root privileges"
 	exit $ksft_skip