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 INET_ECN_is_ce(__u8 dsfield)23 static inline int INET_ECN_is_ce(__u8 dsfield) 24 { 25 return (dsfield & INET_ECN_MASK) == INET_ECN_CE; 26 } 27 INET_ECN_is_not_ect(__u8 dsfield)28 static inline int INET_ECN_is_not_ect(__u8 dsfield) 29 { 30 return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT; 31 } 32 INET_ECN_is_capable(__u8 dsfield)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 */ INET_ECN_encapsulate(__u8 outer,__u8 inner)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 INET_ECN_xmit(struct sock * sk)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 INET_ECN_dontxmit(struct sock * sk)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 IP_ECN_set_ce(struct iphdr * iph)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 IP_ECN_set_ect1(struct iphdr * iph)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 IP_ECN_clear(struct iphdr * iph)115 static inline void IP_ECN_clear(struct iphdr *iph) 116 { 117 iph->tos &= ~INET_ECN_MASK; 118 } 119 ipv4_copy_dscp(unsigned int dscp,struct iphdr * inner)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 */ IP6_ECN_set_ce(struct sk_buff * skb,struct ipv6hdr * iph)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 IP6_ECN_set_ect1(struct sk_buff * skb,struct ipv6hdr * iph)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 ipv6_copy_dscp(unsigned int dscp,struct ipv6hdr * inner)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 INET_ECN_set_ce(struct sk_buff * skb)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 skb_get_dsfield(struct sk_buff * skb)191 static inline int skb_get_dsfield(struct sk_buff *skb) 192 { 193 switch (skb_protocol(skb, true)) { 194 case cpu_to_be16(ETH_P_IP): 195 if (!pskb_network_may_pull(skb, sizeof(struct iphdr))) 196 break; 197 return ipv4_get_dsfield(ip_hdr(skb)); 198 199 case cpu_to_be16(ETH_P_IPV6): 200 if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr))) 201 break; 202 return ipv6_get_dsfield(ipv6_hdr(skb)); 203 } 204 205 return -1; 206 } 207 INET_ECN_set_ect1(struct sk_buff * skb)208 static inline int INET_ECN_set_ect1(struct sk_buff *skb) 209 { 210 switch (skb_protocol(skb, true)) { 211 case cpu_to_be16(ETH_P_IP): 212 if (skb_network_header(skb) + sizeof(struct iphdr) <= 213 skb_tail_pointer(skb)) 214 return IP_ECN_set_ect1(ip_hdr(skb)); 215 break; 216 217 case cpu_to_be16(ETH_P_IPV6): 218 if (skb_network_header(skb) + sizeof(struct ipv6hdr) <= 219 skb_tail_pointer(skb)) 220 return IP6_ECN_set_ect1(skb, ipv6_hdr(skb)); 221 break; 222 } 223 224 return 0; 225 } 226 227 /* 228 * RFC 6040 4.2 229 * To decapsulate the inner header at the tunnel egress, a compliant 230 * tunnel egress MUST set the outgoing ECN field to the codepoint at the 231 * intersection of the appropriate arriving inner header (row) and outer 232 * header (column) in Figure 4 233 * 234 * +---------+------------------------------------------------+ 235 * |Arriving | Arriving Outer Header | 236 * | Inner +---------+------------+------------+------------+ 237 * | Header | Not-ECT | ECT(0) | ECT(1) | CE | 238 * +---------+---------+------------+------------+------------+ 239 * | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)| 240 * | ECT(0) | ECT(0) | ECT(0) | ECT(1) | CE | 241 * | ECT(1) | ECT(1) | ECT(1) (!) | ECT(1) | CE | 242 * | CE | CE | CE | CE(!!!)| CE | 243 * +---------+---------+------------+------------+------------+ 244 * 245 * Figure 4: New IP in IP Decapsulation Behaviour 246 * 247 * returns 0 on success 248 * 1 if something is broken and should be logged (!!! above) 249 * 2 if packet should be dropped 250 */ __INET_ECN_decapsulate(__u8 outer,__u8 inner,bool * set_ce)251 static inline int __INET_ECN_decapsulate(__u8 outer, __u8 inner, bool *set_ce) 252 { 253 if (INET_ECN_is_not_ect(inner)) { 254 switch (outer & INET_ECN_MASK) { 255 case INET_ECN_NOT_ECT: 256 return 0; 257 case INET_ECN_ECT_0: 258 case INET_ECN_ECT_1: 259 return 1; 260 case INET_ECN_CE: 261 return 2; 262 } 263 } 264 265 *set_ce = INET_ECN_is_ce(outer); 266 return 0; 267 } 268 INET_ECN_decapsulate(struct sk_buff * skb,__u8 outer,__u8 inner)269 static inline int INET_ECN_decapsulate(struct sk_buff *skb, 270 __u8 outer, __u8 inner) 271 { 272 bool set_ce = false; 273 int rc; 274 275 rc = __INET_ECN_decapsulate(outer, inner, &set_ce); 276 if (!rc) { 277 if (set_ce) 278 INET_ECN_set_ce(skb); 279 else if ((outer & INET_ECN_MASK) == INET_ECN_ECT_1) 280 INET_ECN_set_ect1(skb); 281 } 282 283 return rc; 284 } 285 IP_ECN_decapsulate(const struct iphdr * oiph,struct sk_buff * skb)286 static inline int IP_ECN_decapsulate(const struct iphdr *oiph, 287 struct sk_buff *skb) 288 { 289 __u8 inner; 290 291 switch (skb_protocol(skb, true)) { 292 case htons(ETH_P_IP): 293 inner = ip_hdr(skb)->tos; 294 break; 295 case htons(ETH_P_IPV6): 296 inner = ipv6_get_dsfield(ipv6_hdr(skb)); 297 break; 298 default: 299 return 0; 300 } 301 302 return INET_ECN_decapsulate(skb, oiph->tos, inner); 303 } 304 IP6_ECN_decapsulate(const struct ipv6hdr * oipv6h,struct sk_buff * skb)305 static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h, 306 struct sk_buff *skb) 307 { 308 __u8 inner; 309 310 switch (skb_protocol(skb, true)) { 311 case htons(ETH_P_IP): 312 inner = ip_hdr(skb)->tos; 313 break; 314 case htons(ETH_P_IPV6): 315 inner = ipv6_get_dsfield(ipv6_hdr(skb)); 316 break; 317 default: 318 return 0; 319 } 320 321 return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner); 322 } 323 #endif 324