1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _INET_ECN_H_ 3 #define _INET_ECN_H_ 4 5 #include <linux/ip.h> 6 #include <linux/skbuff.h> 7 8 #include <net/inet_sock.h> 9 #include <net/dsfield.h> 10 11 enum { 12 INET_ECN_NOT_ECT = 0, 13 INET_ECN_ECT_1 = 1, 14 INET_ECN_ECT_0 = 2, 15 INET_ECN_CE = 3, 16 INET_ECN_MASK = 3, 17 }; 18 19 extern int sysctl_tunnel_ecn_log; 20 21 static inline int INET_ECN_is_ce(__u8 dsfield) 22 { 23 return (dsfield & INET_ECN_MASK) == INET_ECN_CE; 24 } 25 26 static inline int INET_ECN_is_not_ect(__u8 dsfield) 27 { 28 return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT; 29 } 30 31 static inline int INET_ECN_is_capable(__u8 dsfield) 32 { 33 return dsfield & INET_ECN_ECT_0; 34 } 35 36 /* 37 * RFC 3168 9.1.1 38 * The full-functionality option for ECN encapsulation is to copy the 39 * ECN codepoint of the inside header to the outside header on 40 * encapsulation if the inside header is not-ECT or ECT, and to set the 41 * ECN codepoint of the outside header to ECT(0) if the ECN codepoint of 42 * the inside header is CE. 43 */ 44 static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner) 45 { 46 outer &= ~INET_ECN_MASK; 47 outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) : 48 INET_ECN_ECT_0; 49 return outer; 50 } 51 52 static inline void INET_ECN_xmit(struct sock *sk) 53 { 54 inet_sk(sk)->tos |= INET_ECN_ECT_0; 55 if (inet6_sk(sk) != NULL) 56 inet6_sk(sk)->tclass |= INET_ECN_ECT_0; 57 } 58 59 static inline void INET_ECN_dontxmit(struct sock *sk) 60 { 61 inet_sk(sk)->tos &= ~INET_ECN_MASK; 62 if (inet6_sk(sk) != NULL) 63 inet6_sk(sk)->tclass &= ~INET_ECN_MASK; 64 } 65 66 #define IP6_ECN_flow_init(label) do { \ 67 (label) &= ~htonl(INET_ECN_MASK << 20); \ 68 } while (0) 69 70 #define IP6_ECN_flow_xmit(sk, label) do { \ 71 if (INET_ECN_is_capable(inet6_sk(sk)->tclass)) \ 72 (label) |= htonl(INET_ECN_ECT_0 << 20); \ 73 } while (0) 74 75 static inline int IP_ECN_set_ce(struct iphdr *iph) 76 { 77 u32 check = (__force u32)iph->check; 78 u32 ecn = (iph->tos + 1) & INET_ECN_MASK; 79 80 /* 81 * After the last operation we have (in binary): 82 * INET_ECN_NOT_ECT => 01 83 * INET_ECN_ECT_1 => 10 84 * INET_ECN_ECT_0 => 11 85 * INET_ECN_CE => 00 86 */ 87 if (!(ecn & 2)) 88 return !ecn; 89 90 /* 91 * The following gives us: 92 * INET_ECN_ECT_1 => check += htons(0xFFFD) 93 * INET_ECN_ECT_0 => check += htons(0xFFFE) 94 */ 95 check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn); 96 97 iph->check = (__force __sum16)(check + (check>=0xFFFF)); 98 iph->tos |= INET_ECN_CE; 99 return 1; 100 } 101 102 static inline void IP_ECN_clear(struct iphdr *iph) 103 { 104 iph->tos &= ~INET_ECN_MASK; 105 } 106 107 static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner) 108 { 109 dscp &= ~INET_ECN_MASK; 110 ipv4_change_dsfield(inner, INET_ECN_MASK, dscp); 111 } 112 113 struct ipv6hdr; 114 115 /* Note: 116 * IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE, 117 * meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE 118 * In IPv6 case, no checksum compensates the change in IPv6 header, 119 * so we have to update skb->csum. 120 */ 121 static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph) 122 { 123 __be32 from, to; 124 125 if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph))) 126 return 0; 127 128 from = *(__be32 *)iph; 129 to = from | htonl(INET_ECN_CE << 20); 130 *(__be32 *)iph = to; 131 if (skb->ip_summed == CHECKSUM_COMPLETE) 132 skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from), 133 (__force __wsum)to); 134 return 1; 135 } 136 137 static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner) 138 { 139 dscp &= ~INET_ECN_MASK; 140 ipv6_change_dsfield(inner, INET_ECN_MASK, dscp); 141 } 142 143 static inline int INET_ECN_set_ce(struct sk_buff *skb) 144 { 145 switch (skb->protocol) { 146 case cpu_to_be16(ETH_P_IP): 147 if (skb_network_header(skb) + sizeof(struct iphdr) <= 148 skb_tail_pointer(skb)) 149 return IP_ECN_set_ce(ip_hdr(skb)); 150 break; 151 152 case cpu_to_be16(ETH_P_IPV6): 153 if (skb_network_header(skb) + sizeof(struct ipv6hdr) <= 154 skb_tail_pointer(skb)) 155 return IP6_ECN_set_ce(skb, ipv6_hdr(skb)); 156 break; 157 } 158 159 return 0; 160 } 161 162 /* 163 * RFC 6040 4.2 164 * To decapsulate the inner header at the tunnel egress, a compliant 165 * tunnel egress MUST set the outgoing ECN field to the codepoint at the 166 * intersection of the appropriate arriving inner header (row) and outer 167 * header (column) in Figure 4 168 * 169 * +---------+------------------------------------------------+ 170 * |Arriving | Arriving Outer Header | 171 * | Inner +---------+------------+------------+------------+ 172 * | Header | Not-ECT | ECT(0) | ECT(1) | CE | 173 * +---------+---------+------------+------------+------------+ 174 * | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)| 175 * | ECT(0) | ECT(0) | ECT(0) | ECT(1) | CE | 176 * | ECT(1) | ECT(1) | ECT(1) (!) | ECT(1) | CE | 177 * | CE | CE | CE | CE(!!!)| CE | 178 * +---------+---------+------------+------------+------------+ 179 * 180 * Figure 4: New IP in IP Decapsulation Behaviour 181 * 182 * returns 0 on success 183 * 1 if something is broken and should be logged (!!! above) 184 * 2 if packet should be dropped 185 */ 186 static inline int INET_ECN_decapsulate(struct sk_buff *skb, 187 __u8 outer, __u8 inner) 188 { 189 if (INET_ECN_is_not_ect(inner)) { 190 switch (outer & INET_ECN_MASK) { 191 case INET_ECN_NOT_ECT: 192 return 0; 193 case INET_ECN_ECT_0: 194 case INET_ECN_ECT_1: 195 return 1; 196 case INET_ECN_CE: 197 return 2; 198 } 199 } 200 201 if (INET_ECN_is_ce(outer)) 202 INET_ECN_set_ce(skb); 203 204 return 0; 205 } 206 207 static inline int IP_ECN_decapsulate(const struct iphdr *oiph, 208 struct sk_buff *skb) 209 { 210 __u8 inner; 211 212 if (skb->protocol == htons(ETH_P_IP)) 213 inner = ip_hdr(skb)->tos; 214 else if (skb->protocol == htons(ETH_P_IPV6)) 215 inner = ipv6_get_dsfield(ipv6_hdr(skb)); 216 else 217 return 0; 218 219 return INET_ECN_decapsulate(skb, oiph->tos, inner); 220 } 221 222 static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h, 223 struct sk_buff *skb) 224 { 225 __u8 inner; 226 227 if (skb->protocol == htons(ETH_P_IP)) 228 inner = ip_hdr(skb)->tos; 229 else if (skb->protocol == htons(ETH_P_IPV6)) 230 inner = ipv6_get_dsfield(ipv6_hdr(skb)); 231 else 232 return 0; 233 234 return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner); 235 } 236 #endif 237