linux/include/net/inet_ecn.h
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   1#ifndef _INET_ECN_H_
   2#define _INET_ECN_H_
   3
   4#include <linux/ip.h>
   5#include <linux/skbuff.h>
   6
   7#include <net/inet_sock.h>
   8#include <net/dsfield.h>
   9
  10enum {
  11        INET_ECN_NOT_ECT = 0,
  12        INET_ECN_ECT_1 = 1,
  13        INET_ECN_ECT_0 = 2,
  14        INET_ECN_CE = 3,
  15        INET_ECN_MASK = 3,
  16};
  17
  18extern int sysctl_tunnel_ecn_log;
  19
  20static inline int INET_ECN_is_ce(__u8 dsfield)
  21{
  22        return (dsfield & INET_ECN_MASK) == INET_ECN_CE;
  23}
  24
  25static inline int INET_ECN_is_not_ect(__u8 dsfield)
  26{
  27        return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT;
  28}
  29
  30static inline int INET_ECN_is_capable(__u8 dsfield)
  31{
  32        return dsfield & INET_ECN_ECT_0;
  33}
  34
  35/*
  36 * RFC 3168 9.1.1
  37 *  The full-functionality option for ECN encapsulation is to copy the
  38 *  ECN codepoint of the inside header to the outside header on
  39 *  encapsulation if the inside header is not-ECT or ECT, and to set the
  40 *  ECN codepoint of the outside header to ECT(0) if the ECN codepoint of
  41 *  the inside header is CE.
  42 */
  43static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner)
  44{
  45        outer &= ~INET_ECN_MASK;
  46        outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) :
  47                                          INET_ECN_ECT_0;
  48        return outer;
  49}
  50
  51static inline void INET_ECN_xmit(struct sock *sk)
  52{
  53        inet_sk(sk)->tos |= INET_ECN_ECT_0;
  54        if (inet6_sk(sk) != NULL)
  55                inet6_sk(sk)->tclass |= INET_ECN_ECT_0;
  56}
  57
  58static inline void INET_ECN_dontxmit(struct sock *sk)
  59{
  60        inet_sk(sk)->tos &= ~INET_ECN_MASK;
  61        if (inet6_sk(sk) != NULL)
  62                inet6_sk(sk)->tclass &= ~INET_ECN_MASK;
  63}
  64
  65#define IP6_ECN_flow_init(label) do {           \
  66      (label) &= ~htonl(INET_ECN_MASK << 20);   \
  67    } while (0)
  68
  69#define IP6_ECN_flow_xmit(sk, label) do {                               \
  70        if (INET_ECN_is_capable(inet6_sk(sk)->tclass))                  \
  71                (label) |= htonl(INET_ECN_ECT_0 << 20);                 \
  72    } while (0)
  73
  74static inline int IP_ECN_set_ce(struct iphdr *iph)
  75{
  76        u32 check = (__force u32)iph->check;
  77        u32 ecn = (iph->tos + 1) & INET_ECN_MASK;
  78
  79        /*
  80         * After the last operation we have (in binary):
  81         * INET_ECN_NOT_ECT => 01
  82         * INET_ECN_ECT_1   => 10
  83         * INET_ECN_ECT_0   => 11
  84         * INET_ECN_CE      => 00
  85         */
  86        if (!(ecn & 2))
  87                return !ecn;
  88
  89        /*
  90         * The following gives us:
  91         * INET_ECN_ECT_1 => check += htons(0xFFFD)
  92         * INET_ECN_ECT_0 => check += htons(0xFFFE)
  93         */
  94        check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn);
  95
  96        iph->check = (__force __sum16)(check + (check>=0xFFFF));
  97        iph->tos |= INET_ECN_CE;
  98        return 1;
  99}
 100
 101static inline void IP_ECN_clear(struct iphdr *iph)
 102{
 103        iph->tos &= ~INET_ECN_MASK;
 104}
 105
 106static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner)
 107{
 108        dscp &= ~INET_ECN_MASK;
 109        ipv4_change_dsfield(inner, INET_ECN_MASK, dscp);
 110}
 111
 112struct ipv6hdr;
 113
 114static inline int IP6_ECN_set_ce(struct ipv6hdr *iph)
 115{
 116        if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))
 117                return 0;
 118        *(__be32*)iph |= htonl(INET_ECN_CE << 20);
 119        return 1;
 120}
 121
 122static inline void IP6_ECN_clear(struct ipv6hdr *iph)
 123{
 124        *(__be32*)iph &= ~htonl(INET_ECN_MASK << 20);
 125}
 126
 127static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner)
 128{
 129        dscp &= ~INET_ECN_MASK;
 130        ipv6_change_dsfield(inner, INET_ECN_MASK, dscp);
 131}
 132
 133static inline int INET_ECN_set_ce(struct sk_buff *skb)
 134{
 135        switch (skb->protocol) {
 136        case cpu_to_be16(ETH_P_IP):
 137                if (skb->network_header + sizeof(struct iphdr) <= skb->tail)
 138                        return IP_ECN_set_ce(ip_hdr(skb));
 139                break;
 140
 141        case cpu_to_be16(ETH_P_IPV6):
 142                if (skb->network_header + sizeof(struct ipv6hdr) <= skb->tail)
 143                        return IP6_ECN_set_ce(ipv6_hdr(skb));
 144                break;
 145        }
 146
 147        return 0;
 148}
 149
 150/*
 151 * RFC 6080 4.2
 152 *  To decapsulate the inner header at the tunnel egress, a compliant
 153 *  tunnel egress MUST set the outgoing ECN field to the codepoint at the
 154 *  intersection of the appropriate arriving inner header (row) and outer
 155 *  header (column) in Figure 4
 156 *
 157 *      +---------+------------------------------------------------+
 158 *      |Arriving |            Arriving Outer Header               |
 159 *      |   Inner +---------+------------+------------+------------+
 160 *      |  Header | Not-ECT | ECT(0)     | ECT(1)     |     CE     |
 161 *      +---------+---------+------------+------------+------------+
 162 *      | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)|
 163 *      |  ECT(0) |  ECT(0) | ECT(0)     | ECT(1)     |     CE     |
 164 *      |  ECT(1) |  ECT(1) | ECT(1) (!) | ECT(1)     |     CE     |
 165 *      |    CE   |      CE |     CE     |     CE(!!!)|     CE     |
 166 *      +---------+---------+------------+------------+------------+
 167 *
 168 *             Figure 4: New IP in IP Decapsulation Behaviour
 169 *
 170 *  returns 0 on success
 171 *          1 if something is broken and should be logged (!!! above)
 172 *          2 if packet should be dropped
 173 */
 174static inline int INET_ECN_decapsulate(struct sk_buff *skb,
 175                                       __u8 outer, __u8 inner)
 176{
 177        if (INET_ECN_is_not_ect(inner)) {
 178                switch (outer & INET_ECN_MASK) {
 179                case INET_ECN_NOT_ECT:
 180                        return 0;
 181                case INET_ECN_ECT_0:
 182                case INET_ECN_ECT_1:
 183                        return 1;
 184                case INET_ECN_CE:
 185                        return 2;
 186                }
 187        }
 188
 189        if (INET_ECN_is_ce(outer))
 190                INET_ECN_set_ce(skb);
 191
 192        return 0;
 193}
 194
 195static inline int IP_ECN_decapsulate(const struct iphdr *oiph,
 196                                     struct sk_buff *skb)
 197{
 198        __u8 inner;
 199
 200        if (skb->protocol == htons(ETH_P_IP))
 201                inner = ip_hdr(skb)->tos;
 202        else if (skb->protocol == htons(ETH_P_IPV6))
 203                inner = ipv6_get_dsfield(ipv6_hdr(skb));
 204        else
 205                return 0;
 206
 207        return INET_ECN_decapsulate(skb, oiph->tos, inner);
 208}
 209
 210static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h,
 211                                      struct sk_buff *skb)
 212{
 213        __u8 inner;
 214
 215        if (skb->protocol == htons(ETH_P_IP))
 216                inner = ip_hdr(skb)->tos;
 217        else if (skb->protocol == htons(ETH_P_IPV6))
 218                inner = ipv6_get_dsfield(ipv6_hdr(skb));
 219        else
 220                return 0;
 221
 222        return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner);
 223}
 224#endif
 225
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