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 10 enum { 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 18 extern int sysctl_tunnel_ecn_log; 19 20 static inline int INET_ECN_is_ce(__u8 dsfield) 21 { 22 return (dsfield & INET_ECN_MASK) == INET_ECN_CE; 23 } 24 25 static inline int INET_ECN_is_not_ect(__u8 dsfield) 26 { 27 return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT; 28 } 29 30 static 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 */ 43 static 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 51 static 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 58 static 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 74 static 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 } 100 101 static inline void IP_ECN_clear(struct iphdr *iph) 102 { 103 iph->tos &= ~INET_ECN_MASK; 104 } 105 106 static 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 } 111 112 struct ipv6hdr; 113 114 /* Note: 115 * IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE, 116 * meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE 117 * In IPv6 case, no checksum compensates the change in IPv6 header, 118 * so we have to update skb->csum. 119 */ 120 static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph) 121 { 122 __be32 from, to; 123 124 if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph))) 125 return 0; 126 127 from = *(__be32 *)iph; 128 to = from | htonl(INET_ECN_CE << 20); 129 *(__be32 *)iph = to; 130 if (skb->ip_summed == CHECKSUM_COMPLETE) 131 skb->csum = csum_add(csum_sub(skb->csum, from), to); 132 return 1; 133 } 134 135 static inline void IP6_ECN_clear(struct ipv6hdr *iph) 136 { 137 *(__be32*)iph &= ~htonl(INET_ECN_MASK << 20); 138 } 139 140 static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner) 141 { 142 dscp &= ~INET_ECN_MASK; 143 ipv6_change_dsfield(inner, INET_ECN_MASK, dscp); 144 } 145 146 static inline int INET_ECN_set_ce(struct sk_buff *skb) 147 { 148 switch (skb->protocol) { 149 case cpu_to_be16(ETH_P_IP): 150 if (skb_network_header(skb) + sizeof(struct iphdr) <= 151 skb_tail_pointer(skb)) 152 return IP_ECN_set_ce(ip_hdr(skb)); 153 break; 154 155 case cpu_to_be16(ETH_P_IPV6): 156 if (skb_network_header(skb) + sizeof(struct ipv6hdr) <= 157 skb_tail_pointer(skb)) 158 return IP6_ECN_set_ce(skb, ipv6_hdr(skb)); 159 break; 160 } 161 162 return 0; 163 } 164 165 /* 166 * RFC 6040 4.2 167 * To decapsulate the inner header at the tunnel egress, a compliant 168 * tunnel egress MUST set the outgoing ECN field to the codepoint at the 169 * intersection of the appropriate arriving inner header (row) and outer 170 * header (column) in Figure 4 171 * 172 * +---------+------------------------------------------------+ 173 * |Arriving | Arriving Outer Header | 174 * | Inner +---------+------------+------------+------------+ 175 * | Header | Not-ECT | ECT(0) | ECT(1) | CE | 176 * +---------+---------+------------+------------+------------+ 177 * | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)| 178 * | ECT(0) | ECT(0) | ECT(0) | ECT(1) | CE | 179 * | ECT(1) | ECT(1) | ECT(1) (!) | ECT(1) | CE | 180 * | CE | CE | CE | CE(!!!)| CE | 181 * +---------+---------+------------+------------+------------+ 182 * 183 * Figure 4: New IP in IP Decapsulation Behaviour 184 * 185 * returns 0 on success 186 * 1 if something is broken and should be logged (!!! above) 187 * 2 if packet should be dropped 188 */ 189 static inline int INET_ECN_decapsulate(struct sk_buff *skb, 190 __u8 outer, __u8 inner) 191 { 192 if (INET_ECN_is_not_ect(inner)) { 193 switch (outer & INET_ECN_MASK) { 194 case INET_ECN_NOT_ECT: 195 return 0; 196 case INET_ECN_ECT_0: 197 case INET_ECN_ECT_1: 198 return 1; 199 case INET_ECN_CE: 200 return 2; 201 } 202 } 203 204 if (INET_ECN_is_ce(outer)) 205 INET_ECN_set_ce(skb); 206 207 return 0; 208 } 209 210 static inline int IP_ECN_decapsulate(const struct iphdr *oiph, 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, oiph->tos, inner); 223 } 224 225 static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h, 226 struct sk_buff *skb) 227 { 228 __u8 inner; 229 230 if (skb->protocol == htons(ETH_P_IP)) 231 inner = ip_hdr(skb)->tos; 232 else if (skb->protocol == htons(ETH_P_IPV6)) 233 inner = ipv6_get_dsfield(ipv6_hdr(skb)); 234 else 235 return 0; 236 237 return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner); 238 } 239 #endif 240