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 #include <linux/if_vlan.h> 8 9 #include <net/inet_sock.h> 10 #include <net/dsfield.h> 11 #include <net/checksum.h> 12 13 enum { 14 INET_ECN_NOT_ECT = 0, 15 INET_ECN_ECT_1 = 1, 16 INET_ECN_ECT_0 = 2, 17 INET_ECN_CE = 3, 18 INET_ECN_MASK = 3, 19 }; 20 21 extern int sysctl_tunnel_ecn_log; 22 23 static inline int INET_ECN_is_ce(__u8 dsfield) 24 { 25 return (dsfield & INET_ECN_MASK) == INET_ECN_CE; 26 } 27 28 static inline int INET_ECN_is_not_ect(__u8 dsfield) 29 { 30 return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT; 31 } 32 33 static inline int INET_ECN_is_capable(__u8 dsfield) 34 { 35 return dsfield & INET_ECN_ECT_0; 36 } 37 38 /* 39 * RFC 3168 9.1.1 40 * The full-functionality option for ECN encapsulation is to copy the 41 * ECN codepoint of the inside header to the outside header on 42 * encapsulation if the inside header is not-ECT or ECT, and to set the 43 * ECN codepoint of the outside header to ECT(0) if the ECN codepoint of 44 * the inside header is CE. 45 */ 46 static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner) 47 { 48 outer &= ~INET_ECN_MASK; 49 outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) : 50 INET_ECN_ECT_0; 51 return outer; 52 } 53 54 static inline void INET_ECN_xmit(struct sock *sk) 55 { 56 inet_sk(sk)->tos |= INET_ECN_ECT_0; 57 if (inet6_sk(sk) != NULL) 58 inet6_sk(sk)->tclass |= INET_ECN_ECT_0; 59 } 60 61 static inline void INET_ECN_dontxmit(struct sock *sk) 62 { 63 inet_sk(sk)->tos &= ~INET_ECN_MASK; 64 if (inet6_sk(sk) != NULL) 65 inet6_sk(sk)->tclass &= ~INET_ECN_MASK; 66 } 67 68 #define IP6_ECN_flow_init(label) do { \ 69 (label) &= ~htonl(INET_ECN_MASK << 20); \ 70 } while (0) 71 72 #define IP6_ECN_flow_xmit(sk, label) do { \ 73 if (INET_ECN_is_capable(inet6_sk(sk)->tclass)) \ 74 (label) |= htonl(INET_ECN_ECT_0 << 20); \ 75 } while (0) 76 77 static inline int IP_ECN_set_ce(struct iphdr *iph) 78 { 79 u32 ecn = (iph->tos + 1) & INET_ECN_MASK; 80 __be16 check_add; 81 82 /* 83 * After the last operation we have (in binary): 84 * INET_ECN_NOT_ECT => 01 85 * INET_ECN_ECT_1 => 10 86 * INET_ECN_ECT_0 => 11 87 * INET_ECN_CE => 00 88 */ 89 if (!(ecn & 2)) 90 return !ecn; 91 92 /* 93 * The following gives us: 94 * INET_ECN_ECT_1 => check += htons(0xFFFD) 95 * INET_ECN_ECT_0 => check += htons(0xFFFE) 96 */ 97 check_add = (__force __be16)((__force u16)htons(0xFFFB) + 98 (__force u16)htons(ecn)); 99 100 iph->check = csum16_add(iph->check, check_add); 101 iph->tos |= INET_ECN_CE; 102 return 1; 103 } 104 105 static inline int IP_ECN_set_ect1(struct iphdr *iph) 106 { 107 if ((iph->tos & INET_ECN_MASK) != INET_ECN_ECT_0) 108 return 0; 109 110 iph->check = csum16_add(iph->check, htons(0x1)); 111 iph->tos ^= INET_ECN_MASK; 112 return 1; 113 } 114 115 static inline void IP_ECN_clear(struct iphdr *iph) 116 { 117 iph->tos &= ~INET_ECN_MASK; 118 } 119 120 static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner) 121 { 122 dscp &= ~INET_ECN_MASK; 123 ipv4_change_dsfield(inner, INET_ECN_MASK, dscp); 124 } 125 126 struct ipv6hdr; 127 128 /* Note: 129 * IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE, 130 * meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE 131 * In IPv6 case, no checksum compensates the change in IPv6 header, 132 * so we have to update skb->csum. 133 */ 134 static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph) 135 { 136 __be32 from, to; 137 138 if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph))) 139 return 0; 140 141 from = *(__be32 *)iph; 142 to = from | htonl(INET_ECN_CE << 20); 143 *(__be32 *)iph = to; 144 if (skb->ip_summed == CHECKSUM_COMPLETE) 145 skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from), 146 (__force __wsum)to); 147 return 1; 148 } 149 150 static inline int IP6_ECN_set_ect1(struct sk_buff *skb, struct ipv6hdr *iph) 151 { 152 __be32 from, to; 153 154 if ((ipv6_get_dsfield(iph) & INET_ECN_MASK) != INET_ECN_ECT_0) 155 return 0; 156 157 from = *(__be32 *)iph; 158 to = from ^ htonl(INET_ECN_MASK << 20); 159 *(__be32 *)iph = to; 160 if (skb->ip_summed == CHECKSUM_COMPLETE) 161 skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from), 162 (__force __wsum)to); 163 return 1; 164 } 165 166 static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner) 167 { 168 dscp &= ~INET_ECN_MASK; 169 ipv6_change_dsfield(inner, INET_ECN_MASK, dscp); 170 } 171 172 static inline int INET_ECN_set_ce(struct sk_buff *skb) 173 { 174 switch (skb_protocol(skb, true)) { 175 case cpu_to_be16(ETH_P_IP): 176 if (skb_network_header(skb) + sizeof(struct iphdr) <= 177 skb_tail_pointer(skb)) 178 return IP_ECN_set_ce(ip_hdr(skb)); 179 break; 180 181 case cpu_to_be16(ETH_P_IPV6): 182 if (skb_network_header(skb) + sizeof(struct ipv6hdr) <= 183 skb_tail_pointer(skb)) 184 return IP6_ECN_set_ce(skb, ipv6_hdr(skb)); 185 break; 186 } 187 188 return 0; 189 } 190 191 static inline int INET_ECN_set_ect1(struct sk_buff *skb) 192 { 193 switch (skb_protocol(skb, true)) { 194 case cpu_to_be16(ETH_P_IP): 195 if (skb_network_header(skb) + sizeof(struct iphdr) <= 196 skb_tail_pointer(skb)) 197 return IP_ECN_set_ect1(ip_hdr(skb)); 198 break; 199 200 case cpu_to_be16(ETH_P_IPV6): 201 if (skb_network_header(skb) + sizeof(struct ipv6hdr) <= 202 skb_tail_pointer(skb)) 203 return IP6_ECN_set_ect1(skb, ipv6_hdr(skb)); 204 break; 205 } 206 207 return 0; 208 } 209 210 /* 211 * RFC 6040 4.2 212 * To decapsulate the inner header at the tunnel egress, a compliant 213 * tunnel egress MUST set the outgoing ECN field to the codepoint at the 214 * intersection of the appropriate arriving inner header (row) and outer 215 * header (column) in Figure 4 216 * 217 * +---------+------------------------------------------------+ 218 * |Arriving | Arriving Outer Header | 219 * | Inner +---------+------------+------------+------------+ 220 * | Header | Not-ECT | ECT(0) | ECT(1) | CE | 221 * +---------+---------+------------+------------+------------+ 222 * | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)| 223 * | ECT(0) | ECT(0) | ECT(0) | ECT(1) | CE | 224 * | ECT(1) | ECT(1) | ECT(1) (!) | ECT(1) | CE | 225 * | CE | CE | CE | CE(!!!)| CE | 226 * +---------+---------+------------+------------+------------+ 227 * 228 * Figure 4: New IP in IP Decapsulation Behaviour 229 * 230 * returns 0 on success 231 * 1 if something is broken and should be logged (!!! above) 232 * 2 if packet should be dropped 233 */ 234 static inline int __INET_ECN_decapsulate(__u8 outer, __u8 inner, bool *set_ce) 235 { 236 if (INET_ECN_is_not_ect(inner)) { 237 switch (outer & INET_ECN_MASK) { 238 case INET_ECN_NOT_ECT: 239 return 0; 240 case INET_ECN_ECT_0: 241 case INET_ECN_ECT_1: 242 return 1; 243 case INET_ECN_CE: 244 return 2; 245 } 246 } 247 248 *set_ce = INET_ECN_is_ce(outer); 249 return 0; 250 } 251 252 static inline int INET_ECN_decapsulate(struct sk_buff *skb, 253 __u8 outer, __u8 inner) 254 { 255 bool set_ce = false; 256 int rc; 257 258 rc = __INET_ECN_decapsulate(outer, inner, &set_ce); 259 if (!rc) { 260 if (set_ce) 261 INET_ECN_set_ce(skb); 262 else if ((outer & INET_ECN_MASK) == INET_ECN_ECT_1) 263 INET_ECN_set_ect1(skb); 264 } 265 266 return rc; 267 } 268 269 static inline int IP_ECN_decapsulate(const struct iphdr *oiph, 270 struct sk_buff *skb) 271 { 272 __u8 inner; 273 274 switch (skb_protocol(skb, true)) { 275 case htons(ETH_P_IP): 276 inner = ip_hdr(skb)->tos; 277 break; 278 case htons(ETH_P_IPV6): 279 inner = ipv6_get_dsfield(ipv6_hdr(skb)); 280 break; 281 default: 282 return 0; 283 } 284 285 return INET_ECN_decapsulate(skb, oiph->tos, inner); 286 } 287 288 static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h, 289 struct sk_buff *skb) 290 { 291 __u8 inner; 292 293 switch (skb_protocol(skb, true)) { 294 case htons(ETH_P_IP): 295 inner = ip_hdr(skb)->tos; 296 break; 297 case htons(ETH_P_IPV6): 298 inner = ipv6_get_dsfield(ipv6_hdr(skb)); 299 break; 300 default: 301 return 0; 302 } 303 304 return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner); 305 } 306 #endif 307