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/* 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
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