/* SPDX-License-Identifier: GPL-2.0 */#ifndef _INET_ECN_H_#define _INET_ECN_H_ #include <linux/ip.h>#include <linux/skbuff.h>#include <linux/if_vlan.h> #include <net/inet_sock.h>#include <net/dsfield.h>#include <net/checksum.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;} /* Apply either ECT(0) or ECT(1) */static inline void __INET_ECN_xmit(struct sock *sk, bool use_ect_1){	__u8 ect = use_ect_1 ? INET_ECN_ECT_1 : INET_ECN_ECT_0; 	/* Mask the complete byte in case the connection alternates between	 * ECT(0) and ECT(1).	 */	inet_sk(sk)->tos &= ~INET_ECN_MASK;	inet_sk(sk)->tos |= ect;	if (inet6_sk(sk)) {		inet6_sk(sk)->tclass &= ~INET_ECN_MASK;		inet6_sk(sk)->tclass |= ect;	}} static inline void INET_ECN_xmit(struct sock *sk){	__INET_ECN_xmit(sk, false);} 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 ecn = (iph->tos + 1) & INET_ECN_MASK;	__be16 check_add; 	/*	 * 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_add = (__force __be16)((__force u16)htons(0xFFFB) +				     (__force u16)htons(ecn)); 	iph->check = csum16_add(iph->check, check_add);	iph->tos |= INET_ECN_CE;	return 1;} static inline int IP_ECN_set_ect1(struct iphdr *iph){	if ((iph->tos & INET_ECN_MASK) != INET_ECN_ECT_0)		return 0; 	iph->check = csum16_add(iph->check, htons(0x1));	iph->tos ^= INET_ECN_MASK;	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 int IP6_ECN_set_ect1(struct sk_buff *skb, struct ipv6hdr *iph){	__be32 from, to; 	if ((ipv6_get_dsfield(iph) & INET_ECN_MASK) != INET_ECN_ECT_0)		return 0; 	from = *(__be32 *)iph;	to = from ^ htonl(INET_ECN_MASK << 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(skb, true)) {	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;} static inline int skb_get_dsfield(struct sk_buff *skb){	switch (skb_protocol(skb, true)) {	case cpu_to_be16(ETH_P_IP):		if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))			break;		return ipv4_get_dsfield(ip_hdr(skb)); 	case cpu_to_be16(ETH_P_IPV6):		if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))			break;		return ipv6_get_dsfield(ipv6_hdr(skb));	} 	return -1;} static inline int INET_ECN_set_ect1(struct sk_buff *skb){	switch (skb_protocol(skb, true)) {	case cpu_to_be16(ETH_P_IP):		if (skb_network_header(skb) + sizeof(struct iphdr) <=		    skb_tail_pointer(skb))			return IP_ECN_set_ect1(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_ect1(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(__u8 outer, __u8 inner, bool *set_ce){	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;		}	} 	*set_ce = INET_ECN_is_ce(outer);	return 0;} static inline int INET_ECN_decapsulate(struct sk_buff *skb,				       __u8 outer, __u8 inner){	bool set_ce = false;	int rc; 	rc = __INET_ECN_decapsulate(outer, inner, &set_ce);	if (!rc) {		if (set_ce)			INET_ECN_set_ce(skb);		else if ((outer & INET_ECN_MASK) == INET_ECN_ECT_1)			INET_ECN_set_ect1(skb);	} 	return rc;} static inline int IP_ECN_decapsulate(const struct iphdr *oiph,				     struct sk_buff *skb){	__u8 inner; 	switch (skb_protocol(skb, true)) {	case htons(ETH_P_IP):		inner = ip_hdr(skb)->tos;		break;	case htons(ETH_P_IPV6):		inner = ipv6_get_dsfield(ipv6_hdr(skb));		break;	default:		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; 	switch (skb_protocol(skb, true)) {	case htons(ETH_P_IP):		inner = ip_hdr(skb)->tos;		break;	case htons(ETH_P_IPV6):		inner = ipv6_get_dsfield(ipv6_hdr(skb));		break;	default:		return 0;	} 	return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner);}#endif