thr3ads.net - Linux Ethernet Bridging - [Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support [Oct 2022]

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Ido Schimmel

2022-Oct-25 10:00 UTC

[Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support

From: "Hans J. Schultz" <netdev at kapio-technology.com>

Hosts that support 802.1X authentication are able to authenticate
themselves by exchanging EAPOL frames with an authenticator (Ethernet
bridge, in this case) and an authentication server. Access to the
network is only granted by the authenticator to successfully
authenticated hosts.

The above is implemented in the bridge using the "locked" bridge port
option. When enabled, link-local frames (e.g., EAPOL) can be locally
received by the bridge, but all other frames are dropped unless the host
is authenticated. That is, unless the user space control plane installed
an FDB entry according to which the source address of the frame is
located behind the locked ingress port. The entry can be dynamic, in
which case learning needs to be enabled so that the entry will be
refreshed by incoming traffic.

There are deployments in which not all the devices connected to the
authenticator (the bridge) support 802.1X. Such devices can include
printers and cameras. One option to support such deployments is to
unlock the bridge ports connecting these devices, but a slightly more
secure option is to use MAB. When MAB is enabled, the MAC address of the
connected device is used as the user name and password for the
authentication.

For MAB to work, the user space control plane needs to be notified about
MAC addresses that are trying to gain access so that they will be
compared against an allow list. This can be implemented via the regular
learning process with the following differences:

1. Learned FDB entries are installed with a new "locked" flag
indicating
   that the entry cannot be used to authenticate the device. The flag
   cannot be set by user space, but user space can clear the flag by
   replacing the entry, thereby authenticating the device.

2. FDB entries cannot roam to locked ports to prevent unauthenticated
   devices from disrupting traffic destined to already authenticated
   devices.

Enable this behavior using a new bridge port option called "mab". It
can
only be enabled on a bridge port that is both locked and has learning
enabled. A new option is added because there are pure 802.1X deployments
that are not interested in notifications about "locked" FDB entries.

Signed-off-by: Hans J. Schultz <netdev at kapio-technology.com>
Signed-off-by: Ido Schimmel <idosch at nvidia.com>
---

Notes:
    Changes made by me:
    
     * Reword commit message.
     * Reword comment regarding 'NTF_EXT_LOCKED'.
     * Use extack in br_fdb_add().
     * Forbid MAB when learning is disabled.

 include/linux/if_bridge.h      |  1 +
 include/uapi/linux/if_link.h   |  1 +
 include/uapi/linux/neighbour.h |  8 +++++++-
 net/bridge/br_fdb.c            | 24 ++++++++++++++++++++++++
 net/bridge/br_input.c          | 15 +++++++++++++--
 net/bridge/br_netlink.c        | 13 ++++++++++++-
 net/bridge/br_private.h        |  3 ++-
 net/core/rtnetlink.c           |  5 +++++
 8 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index d62ef428e3aa..1668ac4d7adc 100644
--- a/include/linux/if_bridge.h
+++ b/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)
 
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 5e7a1041df3a..d92b3f79eba3 100644
--- a/include/uapi/linux/if_link.h
+++ b/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)
diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
index a998bf761635..5e67a7eaf4a7 100644
--- a/include/uapi/linux/neighbour.h
+++ b/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 {
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index e7f4fccb6adb..3b83af4458b8 100644
--- a/net/bridge/br_fdb.c
+++ b/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,
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 68b3e850bcb9..068fced7693c 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -109,9 +109,20 @@ 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) {
+			unsigned long flags = 0;
+
+			if (p->flags & BR_PORT_MAB) {
+				__set_bit(BR_FDB_LOCKED, &flags);
+				br_fdb_update(br, p, eth_hdr(skb)->h_source,
+					      vid, flags);
+			}
 			goto drop;
+		} else if (READ_ONCE(fdb_src->dst) != p ||
+			   test_bit(BR_FDB_LOCAL, &fdb_src->flags) ||
+			   test_bit(BR_FDB_LOCKED, &fdb_src->flags)) {
+			goto drop;
+		}
 	}
 
 	nbp_switchdev_frame_mark(p, skb);
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 5aeb3646e74c..bbc82c70b091 100644
--- a/net/bridge/br_netlink.c
+++ b/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 +946,14 @@ 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, "MAB can only be enabled on a locked port with
learning enabled");
+		p->flags = old_flags;
+		return -EINVAL;
+	}
 
 	changed_mask = old_flags ^ p->flags;
 
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 06e5f6faa431..4ce8b8e5ae0b 100644
--- a/net/bridge/br_private.h
+++ b/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 {
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 74864dc46a7e..d6e4d2854edb 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -4045,6 +4045,11 @@ 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;
-- 
2.37.3

Nikolay Aleksandrov

2022-Oct-25 11:00 UTC

head link

[Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support

On 25/10/2022 13:00, Ido Schimmel wrote:> From: "Hans J. Schultz" <netdev at kapio-technology.com>
> 
> Hosts that support 802.1X authentication are able to authenticate
> themselves by exchanging EAPOL frames with an authenticator (Ethernet
> bridge, in this case) and an authentication server. Access to the
> network is only granted by the authenticator to successfully
> authenticated hosts.
> 
> The above is implemented in the bridge using the "locked" bridge
port
> option. When enabled, link-local frames (e.g., EAPOL) can be locally
> received by the bridge, but all other frames are dropped unless the host
> is authenticated. That is, unless the user space control plane installed
> an FDB entry according to which the source address of the frame is
> located behind the locked ingress port. The entry can be dynamic, in
> which case learning needs to be enabled so that the entry will be
> refreshed by incoming traffic.
> 
> There are deployments in which not all the devices connected to the
> authenticator (the bridge) support 802.1X. Such devices can include
> printers and cameras. One option to support such deployments is to
> unlock the bridge ports connecting these devices, but a slightly more
> secure option is to use MAB. When MAB is enabled, the MAC address of the
> connected device is used as the user name and password for the
> authentication.
> 
> For MAB to work, the user space control plane needs to be notified about
> MAC addresses that are trying to gain access so that they will be
> compared against an allow list. This can be implemented via the regular
> learning process with the following differences:
> 
> 1. Learned FDB entries are installed with a new "locked" flag
indicating
>    that the entry cannot be used to authenticate the device. The flag
>    cannot be set by user space, but user space can clear the flag by
>    replacing the entry, thereby authenticating the device.
> 
> 2. FDB entries cannot roam to locked ports to prevent unauthenticated
>    devices from disrupting traffic destined to already authenticated
>    devices.
> 
> Enable this behavior using a new bridge port option called "mab".
It can
> only be enabled on a bridge port that is both locked and has learning
> enabled. A new option is added because there are pure 802.1X deployments
> that are not interested in notifications about "locked" FDB
entries.
> 
> Signed-off-by: Hans J. Schultz <netdev at kapio-technology.com>
> Signed-off-by: Ido Schimmel <idosch at nvidia.com>
> ---
> 
> Notes:
>     Changes made by me:
>     
>      * Reword commit message.
>      * Reword comment regarding 'NTF_EXT_LOCKED'.
>      * Use extack in br_fdb_add().
>      * Forbid MAB when learning is disabled.
> 
>  include/linux/if_bridge.h      |  1 +
>  include/uapi/linux/if_link.h   |  1 +
>  include/uapi/linux/neighbour.h |  8 +++++++-
>  net/bridge/br_fdb.c            | 24 ++++++++++++++++++++++++
>  net/bridge/br_input.c          | 15 +++++++++++++--
>  net/bridge/br_netlink.c        | 13 ++++++++++++-
>  net/bridge/br_private.h        |  3 ++-
>  net/core/rtnetlink.c           |  5 +++++
>  8 files changed, 65 insertions(+), 5 deletions(-)
> 
Thanks for finalizing this, the patch looks good to me.
Acked-by: Nikolay Aleksandrov <razor at blackwall.org>

Thanks,
 Nik

Vladimir Oltean

2022-Oct-27 22:58 UTC

head link

[Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support

Hi Ido,

Thanks for the commit message. It is very good.

On Tue, Oct 25, 2022 at 01:00:09PM +0300, Ido Schimmel
wrote:> From: "Hans J. Schultz" <netdev at kapio-technology.com>
> 
> Hosts that support 802.1X authentication are able to authenticate
> themselves by exchanging EAPOL frames with an authenticator (Ethernet
> bridge, in this case) and an authentication server. Access to the
> network is only granted by the authenticator to successfully
> authenticated hosts.
> 
> The above is implemented in the bridge using the "locked" bridge
port
> option. When enabled, link-local frames (e.g., EAPOL) can be locally
> received by the bridge, but all other frames are dropped unless the host
> is authenticated. That is, unless the user space control plane installed
> an FDB entry according to which the source address of the frame is
> located behind the locked ingress port. The entry can be dynamic, in
> which case learning needs to be enabled so that the entry will be
> refreshed by incoming traffic.
> 
> There are deployments in which not all the devices connected to the
> authenticator (the bridge) support 802.1X. Such devices can include
> printers and cameras. One option to support such deployments is to
> unlock the bridge ports connecting these devices, but a slightly more
> secure option is to use MAB. When MAB is enabled, the MAC address of the
> connected device is used as the user name and password for the
> authentication.
> 
> For MAB to work, the user space control plane needs to be notified about
> MAC addresses that are trying to gain access so that they will be
> compared against an allow list. This can be implemented via the regular
> learning process with the following differences:
> 
> 1. Learned FDB entries are installed with a new "locked" flag
indicating
>    that the entry cannot be used to authenticate the device. The flag
>    cannot be set by user space, but user space can clear the flag by
>    replacing the entry, thereby authenticating the device.
> 
> 2. FDB entries cannot roam to locked ports to prevent unauthenticated
>    devices from disrupting traffic destined to already authenticated
>    devices.
The behavior described in (2) has nothing to do with locked FDB entries
or MAB (what is described in this paragraph), it applies to all of them,
no? The code was already there:

	if (p->flags & BR_PORT_LOCKED)
		if (!fdb_src || READ_ONCE(fdb_src->dst) != p ||
		    test_bit(BR_FDB_LOCAL, &fdb_src->flags))
			goto drop;

I think you mean to say: the above already holds true, but the relevant
implication here is that locked FDB entries will not be created if the
MAC address is present in the FDB on any other port?

I think some part of this comment should also go to the convoluted
BR_PORT_LOCKED block from br_handle_frame_finish()?

I was going to ask if we should bother to add code to prohibit packets
from being forwarded to an FDB entry that was learned as LOCKED, since
that FDB entry is more of a "ghost" and not something fully committed?

But with the "never roam to locked port" policy, I don't think
there is
any practical risk that the extra code would mitigate. Assume that a
"snooper" wants to get the traffic destined for a MAC DA X, so it
creates
a LOCKED FDB entry. It has to time itself just right, 5 minutes after
the station it wants to intercept has gone silent (or before the station
said anything). Anyone thinking it's talking to X now talks to the snooper.
But this attack vector is bounded in time. As long as X says anything,
the LOCKED FDB entry moves towards X, and the LOCKED flag gets cleared.
> 
> Enable this behavior using a new bridge port option called "mab".
It can
> only be enabled on a bridge port that is both locked and has learning
> enabled. A new option is added because there are pure 802.1X deployments
> that are not interested in notifications about "locked" FDB
entries.
> 
> Signed-off-by: Hans J. Schultz <netdev at kapio-technology.com>
> Signed-off-by: Ido Schimmel <idosch at nvidia.com>
> ---
> 
> Notes:
>     Changes made by me:
>     
>      * Reword commit message.
>      * Reword comment regarding 'NTF_EXT_LOCKED'.
>      * Use extack in br_fdb_add().
>      * Forbid MAB when learning is disabled.
Forbidding MAB when learning is disabled makes sense to me, since it
means accepting that MAB is a form of learning (as the implementation
also shows; all other callers of br_fdb_update() are guarded by a
port learning check). I believe this will also make life easier with
offloading drivers. Thanks.
>  include/linux/if_bridge.h      |  1 +
>  include/uapi/linux/if_link.h   |  1 +
>  include/uapi/linux/neighbour.h |  8 +++++++-
>  net/bridge/br_fdb.c            | 24 ++++++++++++++++++++++++
>  net/bridge/br_input.c          | 15 +++++++++++++--
>  net/bridge/br_netlink.c        | 13 ++++++++++++-
>  net/bridge/br_private.h        |  3 ++-
>  net/core/rtnetlink.c           |  5 +++++
>  8 files changed, 65 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
> index d62ef428e3aa..1668ac4d7adc 100644
> --- a/include/linux/if_bridge.h
> +++ b/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)
Question about unsetting BR_PORT_MAB using IFLA_BRPORT_MAB: should this
operation flush BR_FDB_LOCKED entries on the port?
> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
> index 68b3e850bcb9..068fced7693c 100644
> --- a/net/bridge/br_input.c
> +++ b/net/bridge/br_input.c
> @@ -109,9 +109,20 @@ 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) {
> +			unsigned long flags = 0;
> +
> +			if (p->flags & BR_PORT_MAB) {
> +				__set_bit(BR_FDB_LOCKED, &flags);
> +				br_fdb_update(br, p, eth_hdr(skb)->h_source,
> +					      vid, flags);
> +			}
>  			goto drop;
> +		} else if (READ_ONCE(fdb_src->dst) != p ||
> +			   test_bit(BR_FDB_LOCAL, &fdb_src->flags) ||
> +			   test_bit(BR_FDB_LOCKED, &fdb_src->flags)) {
Minor nitpick: shouldn't br_fdb_update() also be called when the packet
matched on a BR_FDB_LOCKED entry on port p, so as to refresh it, if the
station is persistent? Currently I believe the FDB entry will expire
within 5 minutes of the first packet, regardless of subsequent traffic.
> +			goto drop;
> +		}
>  	}
>  
>  	nbp_switchdev_frame_mark(p, skb);

netdev at kapio-technology.com

2022-Oct-30 22:09 UTC

head link

[Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support

On 2022-10-25 12:00, Ido Schimmel wrote:> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
> index 5aeb3646e74c..bbc82c70b091 100644
> --- a/net/bridge/br_netlink.c
> +++ b/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 +946,14 @@ 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, "MAB can only be enabled on a locked port
> with learning enabled");
It's a bit odd to get this message when turning off learning on a port 
with MAB on, e.g....

# bridge link set dev a2 learning off
Error: MAB can only be enabled on a locked port with learning enabled.

Linux Ethernet Bridging - Oct 2022 - [Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support

[Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support

[Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support

[Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support

[Bridge] [RFC PATCH net-next 01/16] bridge: Add MAC Authentication Bypass (MAB) support