v4.19.13 snapshot.
diff --git a/include/net/inet_ecn.h b/include/net/inet_ecn.h
new file mode 100644
index 0000000..482a1b7
--- /dev/null
+++ b/include/net/inet_ecn.h
@@ -0,0 +1,236 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _INET_ECN_H_
+#define _INET_ECN_H_
+
+#include <linux/ip.h>
+#include <linux/skbuff.h>
+
+#include <net/inet_sock.h>
+#include <net/dsfield.h>
+
+enum {
+ INET_ECN_NOT_ECT = 0,
+ INET_ECN_ECT_1 = 1,
+ INET_ECN_ECT_0 = 2,
+ INET_ECN_CE = 3,
+ 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;
+}
+
+static inline int INET_ECN_is_not_ect(__u8 dsfield)
+{
+ return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT;
+}
+
+static inline int INET_ECN_is_capable(__u8 dsfield)
+{
+ return dsfield & INET_ECN_ECT_0;
+}
+
+/*
+ * RFC 3168 9.1.1
+ * The full-functionality option for ECN encapsulation is to copy the
+ * ECN codepoint of the inside header to the outside header on
+ * encapsulation if the inside header is not-ECT or ECT, and to set the
+ * ECN codepoint of the outside header to ECT(0) if the ECN codepoint of
+ * the inside header is CE.
+ */
+static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner)
+{
+ outer &= ~INET_ECN_MASK;
+ outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) :
+ INET_ECN_ECT_0;
+ return outer;
+}
+
+static inline void INET_ECN_xmit(struct sock *sk)
+{
+ inet_sk(sk)->tos |= INET_ECN_ECT_0;
+ if (inet6_sk(sk) != NULL)
+ inet6_sk(sk)->tclass |= INET_ECN_ECT_0;
+}
+
+static inline void INET_ECN_dontxmit(struct sock *sk)
+{
+ inet_sk(sk)->tos &= ~INET_ECN_MASK;
+ if (inet6_sk(sk) != NULL)
+ inet6_sk(sk)->tclass &= ~INET_ECN_MASK;
+}
+
+#define IP6_ECN_flow_init(label) do { \
+ (label) &= ~htonl(INET_ECN_MASK << 20); \
+ } while (0)
+
+#define IP6_ECN_flow_xmit(sk, label) do { \
+ if (INET_ECN_is_capable(inet6_sk(sk)->tclass)) \
+ (label) |= htonl(INET_ECN_ECT_0 << 20); \
+ } while (0)
+
+static inline int IP_ECN_set_ce(struct iphdr *iph)
+{
+ u32 check = (__force u32)iph->check;
+ u32 ecn = (iph->tos + 1) & INET_ECN_MASK;
+
+ /*
+ * After the last operation we have (in binary):
+ * INET_ECN_NOT_ECT => 01
+ * INET_ECN_ECT_1 => 10
+ * INET_ECN_ECT_0 => 11
+ * INET_ECN_CE => 00
+ */
+ if (!(ecn & 2))
+ return !ecn;
+
+ /*
+ * The following gives us:
+ * INET_ECN_ECT_1 => check += htons(0xFFFD)
+ * INET_ECN_ECT_0 => check += htons(0xFFFE)
+ */
+ check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn);
+
+ iph->check = (__force __sum16)(check + (check>=0xFFFF));
+ iph->tos |= INET_ECN_CE;
+ return 1;
+}
+
+static inline void IP_ECN_clear(struct iphdr *iph)
+{
+ iph->tos &= ~INET_ECN_MASK;
+}
+
+static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner)
+{
+ dscp &= ~INET_ECN_MASK;
+ ipv4_change_dsfield(inner, INET_ECN_MASK, dscp);
+}
+
+struct ipv6hdr;
+
+/* Note:
+ * IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE,
+ * meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE
+ * In IPv6 case, no checksum compensates the change in IPv6 header,
+ * so we have to update skb->csum.
+ */
+static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph)
+{
+ __be32 from, to;
+
+ if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))
+ return 0;
+
+ from = *(__be32 *)iph;
+ to = from | htonl(INET_ECN_CE << 20);
+ *(__be32 *)iph = to;
+ if (skb->ip_summed == CHECKSUM_COMPLETE)
+ skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from),
+ (__force __wsum)to);
+ return 1;
+}
+
+static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner)
+{
+ dscp &= ~INET_ECN_MASK;
+ ipv6_change_dsfield(inner, INET_ECN_MASK, dscp);
+}
+
+static inline int INET_ECN_set_ce(struct sk_buff *skb)
+{
+ switch (skb->protocol) {
+ case cpu_to_be16(ETH_P_IP):
+ if (skb_network_header(skb) + sizeof(struct iphdr) <=
+ skb_tail_pointer(skb))
+ return IP_ECN_set_ce(ip_hdr(skb));
+ break;
+
+ case cpu_to_be16(ETH_P_IPV6):
+ if (skb_network_header(skb) + sizeof(struct ipv6hdr) <=
+ skb_tail_pointer(skb))
+ return IP6_ECN_set_ce(skb, ipv6_hdr(skb));
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * RFC 6040 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