4 files changed, 147 insertions, 63 deletions

diff --git a/include/net/inet_ecn.h b/include/net/inet_ecn.h
index 2fa14691869c..aab73757bc4d 100644
--- a/include/net/inet_ecn.h
+++ b/include/net/inet_ecn.h
@@ -15,6 +15,8 @@ enum {
         INET_ECN_MASK = 3,
 };
 
+extern int sysctl_tunnel_ecn_log;
+
 static inline int INET_ECN_is_ce(__u8 dsfield)
 {
         return (dsfield & INET_ECN_MASK) == INET_ECN_CE;
@@ -145,4 +147,78 @@ static inline int INET_ECN_set_ce(struct sk_buff *skb)
         return 0;
 }
 
+/*
+ * RFC 6080 4.2
+ *  To decapsulate the inner header at the tunnel egress, a compliant
+ *  tunnel egress MUST set the outgoing ECN field to the codepoint at the
+ *  intersection of the appropriate arriving inner header (row) and outer
+ *  header (column) in Figure 4
+ *
+ *      +---------+------------------------------------------------+
+ *      |Arriving |            Arriving Outer Header               |
+ *      |   Inner +---------+------------+------------+------------+
+ *      |  Header | Not-ECT | ECT(0)     | ECT(1)     |     CE     |
+ *      +---------+---------+------------+------------+------------+
+ *      | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)|
+ *      |  ECT(0) |  ECT(0) | ECT(0)     | ECT(1)     |     CE     |
+ *      |  ECT(1) |  ECT(1) | ECT(1) (!) | ECT(1)     |     CE     |
+ *      |    CE   |      CE |     CE     |     CE(!!!)|     CE     |
+ *      +---------+---------+------------+------------+------------+
+ *
+ *             Figure 4: New IP in IP Decapsulation Behaviour
+ *
+ *  returns 0 on success
+ *          1 if something is broken and should be logged (!!! above)
+ *          2 if packet should be dropped
+ */
+static inline int INET_ECN_decapsulate(struct sk_buff *skb,
+                                       __u8 outer, __u8 inner)
+{
+        if (INET_ECN_is_not_ect(inner)) {
+                switch (outer & INET_ECN_MASK) {
+                case INET_ECN_NOT_ECT:
+                        return 0;
+                case INET_ECN_ECT_0:
+                case INET_ECN_ECT_1:
+                        return 1;
+                case INET_ECN_CE:
+                        return 2;
+                }
+        }
+
+        if (INET_ECN_is_ce(outer))
+                INET_ECN_set_ce(skb);
+
+        return 0;
+}
+
+static inline int IP_ECN_decapsulate(const struct iphdr *oiph,
+                                     struct sk_buff *skb)
+{
+        __u8 inner;
+
+        if (skb->protocol == htons(ETH_P_IP))
+                inner = ip_hdr(skb)->tos;
+        else if (skb->protocol == htons(ETH_P_IPV6))
+                inner = ipv6_get_dsfield(ipv6_hdr(skb));
+        else
+                return 0;
+
+        return INET_ECN_decapsulate(skb, oiph->tos, inner);
+}
+
+static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h,
+                                      struct sk_buff *skb)
+{
+        __u8 inner;
+
+        if (skb->protocol == htons(ETH_P_IP))
+                inner = ip_hdr(skb)->tos;
+        else if (skb->protocol == htons(ETH_P_IPV6))
+                inner = ipv6_get_dsfield(ipv6_hdr(skb));
+        else
+                return 0;
+
+        return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner);
+}
 #endif
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 1c012cb2cb94..ef0b861ce044 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -120,6 +120,10 @@
    Alexey Kuznetsov.
  */
 
+static bool log_ecn_error = true;
+module_param(log_ecn_error, bool, 0644);
+MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
+
 static struct rtnl_link_ops ipgre_link_ops __read_mostly;
 static int ipgre_tunnel_init(struct net_device *dev);
 static void ipgre_tunnel_setup(struct net_device *dev);
@@ -204,7 +208,9 @@ static struct rtnl_link_stats64 *ipgre_get_stats64(struct net_device *dev,
         tot->rx_crc_errors = dev->stats.rx_crc_errors;
         tot->rx_fifo_errors = dev->stats.rx_fifo_errors;
         tot->rx_length_errors = dev->stats.rx_length_errors;
+        tot->rx_frame_errors = dev->stats.rx_frame_errors;
         tot->rx_errors = dev->stats.rx_errors;
+
         tot->tx_fifo_errors = dev->stats.tx_fifo_errors;
         tot->tx_carrier_errors = dev->stats.tx_carrier_errors;
         tot->tx_dropped = dev->stats.tx_dropped;
@@ -587,17 +593,6 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
         t->err_time = jiffies;
 }
 
-static inline void ipgre_ecn_decapsulate(const struct iphdr *iph, struct sk_buff *skb)
-{
-        if (INET_ECN_is_ce(iph->tos)) {
-                if (skb->protocol == htons(ETH_P_IP)) {
-                        IP_ECN_set_ce(ip_hdr(skb));
-                } else if (skb->protocol == htons(ETH_P_IPV6)) {
-                        IP6_ECN_set_ce(ipv6_hdr(skb));
-                }
-        }
-}
-
 static inline u8
 ipgre_ecn_encapsulate(u8 tos, const struct iphdr *old_iph, struct sk_buff *skb)
 {
@@ -620,6 +615,7 @@ static int ipgre_rcv(struct sk_buff *skb)
         struct ip_tunnel *tunnel;
         int    offset = 4;
         __be16 gre_proto;
+        int    err;
 
         if (!pskb_may_pull(skb, 16))
                 goto drop;
@@ -723,17 +719,27 @@ static int ipgre_rcv(struct sk_buff *skb)
                         skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
                 }
 
+                __skb_tunnel_rx(skb, tunnel->dev);
+
+                skb_reset_network_header(skb);
+                err = IP_ECN_decapsulate(iph, skb);
+                if (unlikely(err)) {
+                        if (log_ecn_error)
+                                net_info_ratelimited("non-ECT from %pI4 with TOS=%#x\n",
+                                                     &iph->saddr, iph->tos);
+                        if (err > 1) {
+                                ++tunnel->dev->stats.rx_frame_errors;
+                                ++tunnel->dev->stats.rx_errors;
+                                goto drop;
+                        }
+                }
+
                 tstats = this_cpu_ptr(tunnel->dev->tstats);
                 u64_stats_update_begin(&tstats->syncp);
                 tstats->rx_packets++;
                 tstats->rx_bytes += skb->len;
                 u64_stats_update_end(&tstats->syncp);
 
-                __skb_tunnel_rx(skb, tunnel->dev);
-
-                skb_reset_network_header(skb);
-                ipgre_ecn_decapsulate(iph, skb);
-
                 netif_rx(skb);
 
                 return 0;
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 618bde867ac1..e15b45297c09 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -120,6 +120,10 @@
 #define HASH_SIZE  16
 #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
 
+static bool log_ecn_error = true;
+module_param(log_ecn_error, bool, 0644);
+MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");