3 files changed, 30 insertions, 0 deletions

diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index f7d47c89d658..a22caf9e5a18 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -1029,6 +1029,9 @@ static int __tipc_nl_add_media(struct tipc_nl_msg *msg,
 		goto prop_msg_full;
 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, media->window))
 		goto prop_msg_full;
+	if (media->type_id == TIPC_MEDIA_TYPE_UDP)
+		if (nla_put_u32(msg->skb, TIPC_NLA_PROP_MTU, media->mtu))
+			goto prop_msg_full;
 
 	nla_nest_end(msg->skb, prop);
 	nla_nest_end(msg->skb, attrs);
@@ -1158,6 +1161,16 @@ int __tipc_nl_media_set(struct sk_buff *skb, struct genl_info *info)
 			m->priority = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
 		if (props[TIPC_NLA_PROP_WIN])
 			m->window = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
+		if (props[TIPC_NLA_PROP_MTU]) {
+			if (m->type_id != TIPC_MEDIA_TYPE_UDP)
+				return -EINVAL;
+#ifdef CONFIG_TIPC_MEDIA_UDP
+			if (tipc_udp_mtu_bad(nla_get_u32
+					     (props[TIPC_NLA_PROP_MTU])))
+				return -EINVAL;
+			m->mtu = nla_get_u32(props[TIPC_NLA_PROP_MTU]);
+#endif
+		}
 	}
 
 	return 0;
diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
index 6efcee63a381..394290cbbb1d 100644
--- a/net/tipc/bearer.h
+++ b/net/tipc/bearer.h
@@ -94,6 +94,8 @@ struct tipc_bearer;
  * @priority: default link (and bearer) priority
  * @tolerance: default time (in ms) before declaring link failure
  * @window: default window (in packets) before declaring link congestion
+ * @mtu: max packet size bearer can support for media type not dependent on
+ * underlying device MTU
  * @type_id: TIPC media identifier
  * @hwaddr_len: TIPC media address len
  * @name: media name
@@ -118,6 +120,7 @@ struct tipc_media {
 	u32 priority;
 	u32 tolerance;
 	u32 window;
+	u32 mtu;
 	u32 type_id;
 	u32 hwaddr_len;
 	char name[TIPC_MAX_MEDIA_NAME];
diff --git a/net/tipc/udp_media.h b/net/tipc/udp_media.h
index 281bbae87726..e7455cc73e16 100644
--- a/net/tipc/udp_media.h
+++ b/net/tipc/udp_media.h
@@ -38,9 +38,23 @@
 #ifndef _TIPC_UDP_MEDIA_H
 #define _TIPC_UDP_MEDIA_H
 
+#include <linux/ip.h>
+#include <linux/udp.h>
+
 int tipc_udp_nl_bearer_add(struct tipc_bearer *b, struct nlattr *attr);
 int tipc_udp_nl_add_bearer_data(struct tipc_nl_msg *msg, struct tipc_bearer *b);
 int tipc_udp_nl_dump_remoteip(struct sk_buff *skb, struct netlink_callback *cb);
 
+/* check if configured MTU is too low for tipc headers */
+static inline bool tipc_udp_mtu_bad(u32 mtu)
+{
+	if (mtu >= (TIPC_MIN_BEARER_MTU + sizeof(struct iphdr) +
+	    sizeof(struct udphdr)))
+		return false;
+
+	pr_warn("MTU too low for tipc bearer\n");
+	return true;
+}
+
 #endif
 #endif