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 int IP_ECN_set_ect1(struct iphdr *iph) 103 { 104 u32 check = (__force u32)iph->check; 105 106 if ((iph->tos & INET_ECN_MASK) != INET_ECN_ECT_0) 107 return 0; 108 109 check += (__force u16)htons(0x100); 110 111 iph->check = (__force __sum16)(check + (check>=0xFFFF)); 112 iph->tos ^= INET_ECN_MASK; 113 return 1; 114 } 115 116 static inline void IP_ECN_clear(struct iphdr *iph) 117 { 118 iph->tos &= ~INET_ECN_MASK; 119 } 120 121 static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner) 122 { 123 dscp &= ~INET_ECN_MASK; 124 ipv4_change_dsfield(inner, INET_ECN_MASK, dscp); 125 } 126 127 struct ipv6hdr; 128 129 /* Note: 130 * IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE, 131 * meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE 132 * In IPv6 case, no checksum compensates the change in IPv6 header, 133 * so we have to update skb->csum. 134 */ 135 static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph) 136 { 137 __be32 from, to; 138 139 if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph))) 140 return 0; 141 142 from = *(__be32 *)iph; 143 to = from | htonl(INET_ECN_CE << 20); 144 *(__be32 *)iph = to; 145 if (skb->ip_summed == CHECKSUM_COMPLETE) 146 skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from), 147 (__force __wsum)to); 148 return 1; 149 } 150 151 static inline int IP6_ECN_set_ect1(struct sk_buff *skb, struct ipv6hdr *iph) 152 { 153 __be32 from, to; 154 155 if ((ipv6_get_dsfield(iph) & INET_ECN_MASK) != INET_ECN_ECT_0) 156 return 0; 157 158 from = *(__be32 *)iph; 159 to = from ^ htonl(INET_ECN_MASK << 20); 160 *(__be32 *)iph = to; 161 if (skb->ip_summed == CHECKSUM_COMPLETE) 162 skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from), 163 (__force __wsum)to); 164 return 1; 165 } 166 167 static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner) 168 { 169 dscp &= ~INET_ECN_MASK; 170 ipv6_change_dsfield(inner, INET_ECN_MASK, dscp); 171 } 172 173 static inline int INET_ECN_set_ce(struct sk_buff *skb) 174 { 175 switch (skb->protocol) { 176 case cpu_to_be16(ETH_P_IP): 177 if (skb_network_header(skb) + sizeof(struct iphdr) <= 178 skb_tail_pointer(skb)) 179 return IP_ECN_set_ce(ip_hdr(skb)); 180 break; 181 182 case cpu_to_be16(ETH_P_IPV6): 183 if (skb_network_header(skb) + sizeof(struct ipv6hdr) <= 184 skb_tail_pointer(skb)) 185 return IP6_ECN_set_ce(skb, ipv6_hdr(skb)); 186 break; 187 } 188 189 return 0; 190 } 191 192 static inline int INET_ECN_set_ect1(struct sk_buff *skb) 193 { 194 switch (skb->protocol) { 195 case cpu_to_be16(ETH_P_IP): 196 if (skb_network_header(skb) + sizeof(struct iphdr) <= 197 skb_tail_pointer(skb)) 198 return IP_ECN_set_ect1(ip_hdr(skb)); 199 break; 200 201 case cpu_to_be16(ETH_P_IPV6): 202 if (skb_network_header(skb) + sizeof(struct ipv6hdr) <= 203 skb_tail_pointer(skb)) 204 return IP6_ECN_set_ect1(skb, ipv6_hdr(skb)); 205 break; 206 } 207 208 return 0; 209 } 210 211 /* 212 * RFC 6040 4.2 213 * To decapsulate the inner header at the tunnel egress, a compliant 214 * tunnel egress MUST set the outgoing ECN field to the codepoint at the 215 * intersection of the appropriate arriving inner header (row) and outer 216 * header (column) in Figure 4 217 * 218 * +---------+------------------------------------------------+ 219 * |Arriving | Arriving Outer Header | 220 * | Inner +---------+------------+------------+------------+ 221 * | Header | Not-ECT | ECT(0) | ECT(1) | CE | 222 * +---------+---------+------------+------------+------------+ 223 * | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)| 224 * | ECT(0) | ECT(0) | ECT(0) | ECT(1) | CE | 225 * | ECT(1) | ECT(1) | ECT(1) (!) | ECT(1) | CE | 226 * | CE | CE | CE | CE(!!!)| CE | 227 * +---------+---------+------------+------------+------------+ 228 * 229 * Figure 4: New IP in IP Decapsulation Behaviour 230 * 231 * returns 0 on success 232 * 1 if something is broken and should be logged (!!! above) 233 * 2 if packet should be dropped 234 */ 235 static inline int __INET_ECN_decapsulate(__u8 outer, __u8 inner, bool *set_ce) 236 { 237 if (INET_ECN_is_not_ect(inner)) { 238 switch (outer & INET_ECN_MASK) { 239 case INET_ECN_NOT_ECT: 240 return 0; 241 case INET_ECN_ECT_0: 242 case INET_ECN_ECT_1: 243 return 1; 244 case INET_ECN_CE: 245 return 2; 246 } 247 } 248 249 *set_ce = INET_ECN_is_ce(outer); 250 return 0; 251 } 252 253 static inline int INET_ECN_decapsulate(struct sk_buff *skb, 254 __u8 outer, __u8 inner) 255 { 256 bool set_ce = false; 257 int rc; 258 259 rc = __INET_ECN_decapsulate(outer, inner, &set_ce); 260 if (!rc) { 261 if (set_ce) 262 INET_ECN_set_ce(skb); 263 else if ((outer & INET_ECN_MASK) == INET_ECN_ECT_1) 264 INET_ECN_set_ect1(skb); 265 } 266 267 return rc; 268 } 269 270 static inline int IP_ECN_decapsulate(const struct iphdr *oiph, 271 struct sk_buff *skb) 272 { 273 __u8 inner; 274 275 if (skb->protocol == htons(ETH_P_IP)) 276 inner = ip_hdr(skb)->tos; 277 else if (skb->protocol == htons(ETH_P_IPV6)) 278 inner = ipv6_get_dsfield(ipv6_hdr(skb)); 279 else 280 return 0; 281 282 return INET_ECN_decapsulate(skb, oiph->tos, inner); 283 } 284 285 static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h, 286 struct sk_buff *skb) 287 { 288 __u8 inner; 289 290 if (skb->protocol == htons(ETH_P_IP)) 291 inner = ip_hdr(skb)->tos; 292 else if (skb->protocol == htons(ETH_P_IPV6)) 293 inner = ipv6_get_dsfield(ipv6_hdr(skb)); 294 else 295 return 0; 296 297 return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner); 298 } 299 #endif 300