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
12 enum {
13 INET_ECN_NOT_ECT = 0,
14 INET_ECN_ECT_1 = 1,
15 INET_ECN_ECT_0 = 2,
16 INET_ECN_CE = 3,
17 INET_ECN_MASK = 3,
18 };
19
20 extern int sysctl_tunnel_ecn_log;
21
INET_ECN_is_ce(__u8 dsfield)22 static inline int INET_ECN_is_ce(__u8 dsfield)
23 {
24 return (dsfield & INET_ECN_MASK) == INET_ECN_CE;
25 }
26
INET_ECN_is_not_ect(__u8 dsfield)27 static inline int INET_ECN_is_not_ect(__u8 dsfield)
28 {
29 return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT;
30 }
31
INET_ECN_is_capable(__u8 dsfield)32 static inline int INET_ECN_is_capable(__u8 dsfield)
33 {
34 return dsfield & INET_ECN_ECT_0;
35 }
36
37 /*
38 * RFC 3168 9.1.1
39 * The full-functionality option for ECN encapsulation is to copy the
40 * ECN codepoint of the inside header to the outside header on
41 * encapsulation if the inside header is not-ECT or ECT, and to set the
42 * ECN codepoint of the outside header to ECT(0) if the ECN codepoint of
43 * the inside header is CE.
44 */
INET_ECN_encapsulate(__u8 outer,__u8 inner)45 static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner)
46 {
47 outer &= ~INET_ECN_MASK;
48 outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) :
49 INET_ECN_ECT_0;
50 return outer;
51 }
52
INET_ECN_xmit(struct sock * sk)53 static inline void INET_ECN_xmit(struct sock *sk)
54 {
55 inet_sk(sk)->tos |= INET_ECN_ECT_0;
56 if (inet6_sk(sk) != NULL)
57 inet6_sk(sk)->tclass |= INET_ECN_ECT_0;
58 }
59
INET_ECN_dontxmit(struct sock * sk)60 static inline void INET_ECN_dontxmit(struct sock *sk)
61 {
62 inet_sk(sk)->tos &= ~INET_ECN_MASK;
63 if (inet6_sk(sk) != NULL)
64 inet6_sk(sk)->tclass &= ~INET_ECN_MASK;
65 }
66
67 #define IP6_ECN_flow_init(label) do { \
68 (label) &= ~htonl(INET_ECN_MASK << 20); \
69 } while (0)
70
71 #define IP6_ECN_flow_xmit(sk, label) do { \
72 if (INET_ECN_is_capable(inet6_sk(sk)->tclass)) \
73 (label) |= htonl(INET_ECN_ECT_0 << 20); \
74 } while (0)
75
IP_ECN_set_ce(struct iphdr * iph)76 static inline int IP_ECN_set_ce(struct iphdr *iph)
77 {
78 u32 check = (__force u32)iph->check;
79 u32 ecn = (iph->tos + 1) & INET_ECN_MASK;
80
81 /*
82 * After the last operation we have (in binary):
83 * INET_ECN_NOT_ECT => 01
84 * INET_ECN_ECT_1 => 10
85 * INET_ECN_ECT_0 => 11
86 * INET_ECN_CE => 00
87 */
88 if (!(ecn & 2))
89 return !ecn;
90
91 /*
92 * The following gives us:
93 * INET_ECN_ECT_1 => check += htons(0xFFFD)
94 * INET_ECN_ECT_0 => check += htons(0xFFFE)
95 */
96 check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn);
97
98 iph->check = (__force __sum16)(check + (check>=0xFFFF));
99 iph->tos |= INET_ECN_CE;
100 return 1;
101 }
102
IP_ECN_clear(struct iphdr * iph)103 static inline void IP_ECN_clear(struct iphdr *iph)
104 {
105 iph->tos &= ~INET_ECN_MASK;
106 }
107
ipv4_copy_dscp(unsigned int dscp,struct iphdr * inner)108 static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner)
109 {
110 dscp &= ~INET_ECN_MASK;
111 ipv4_change_dsfield(inner, INET_ECN_MASK, dscp);
112 }
113
114 struct ipv6hdr;
115
116 /* Note:
117 * IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE,
118 * meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE
119 * In IPv6 case, no checksum compensates the change in IPv6 header,
120 * so we have to update skb->csum.
121 */
IP6_ECN_set_ce(struct sk_buff * skb,struct ipv6hdr * iph)122 static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph)
123 {
124 __be32 from, to;
125
126 if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))
127 return 0;
128
129 from = *(__be32 *)iph;
130 to = from | htonl(INET_ECN_CE << 20);
131 *(__be32 *)iph = to;
132 if (skb->ip_summed == CHECKSUM_COMPLETE)
133 skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from),
134 (__force __wsum)to);
135 return 1;
136 }
137
ipv6_copy_dscp(unsigned int dscp,struct ipv6hdr * inner)138 static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner)
139 {
140 dscp &= ~INET_ECN_MASK;
141 ipv6_change_dsfield(inner, INET_ECN_MASK, dscp);
142 }
143
INET_ECN_set_ce(struct sk_buff * skb)144 static inline int INET_ECN_set_ce(struct sk_buff *skb)
145 {
146 switch (skb_protocol(skb, true)) {
147 case cpu_to_be16(ETH_P_IP):
148 if (skb_network_header(skb) + sizeof(struct iphdr) <=
149 skb_tail_pointer(skb))
150 return IP_ECN_set_ce(ip_hdr(skb));
151 break;
152
153 case cpu_to_be16(ETH_P_IPV6):
154 if (skb_network_header(skb) + sizeof(struct ipv6hdr) <=
155 skb_tail_pointer(skb))
156 return IP6_ECN_set_ce(skb, ipv6_hdr(skb));
157 break;
158 }
159
160 return 0;
161 }
162
163 /*
164 * RFC 6040 4.2
165 * To decapsulate the inner header at the tunnel egress, a compliant
166 * tunnel egress MUST set the outgoing ECN field to the codepoint at the
167 * intersection of the appropriate arriving inner header (row) and outer
168 * header (column) in Figure 4
169 *
170 * +---------+------------------------------------------------+
171 * |Arriving | Arriving Outer Header |
172 * | Inner +---------+------------+------------+------------+
173 * | Header | Not-ECT | ECT(0) | ECT(1) | CE |
174 * +---------+---------+------------+------------+------------+
175 * | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)|
176 * | ECT(0) | ECT(0) | ECT(0) | ECT(1) | CE |
177 * | ECT(1) | ECT(1) | ECT(1) (!) | ECT(1) | CE |
178 * | CE | CE | CE | CE(!!!)| CE |
179 * +---------+---------+------------+------------+------------+
180 *
181 * Figure 4: New IP in IP Decapsulation Behaviour
182 *
183 * returns 0 on success
184 * 1 if something is broken and should be logged (!!! above)
185 * 2 if packet should be dropped
186 */
INET_ECN_decapsulate(struct sk_buff * skb,__u8 outer,__u8 inner)187 static inline int INET_ECN_decapsulate(struct sk_buff *skb,
188 __u8 outer, __u8 inner)
189 {
190 if (INET_ECN_is_not_ect(inner)) {
191 switch (outer & INET_ECN_MASK) {
192 case INET_ECN_NOT_ECT:
193 return 0;
194 case INET_ECN_ECT_0:
195 case INET_ECN_ECT_1:
196 return 1;
197 case INET_ECN_CE:
198 return 2;
199 }
200 }
201
202 if (INET_ECN_is_ce(outer))
203 INET_ECN_set_ce(skb);
204
205 return 0;
206 }
207
IP_ECN_decapsulate(const struct iphdr * oiph,struct sk_buff * skb)208 static inline int IP_ECN_decapsulate(const struct iphdr *oiph,
209 struct sk_buff *skb)
210 {
211 __u8 inner;
212
213 switch (skb_protocol(skb, true)) {
214 case htons(ETH_P_IP):
215 inner = ip_hdr(skb)->tos;
216 break;
217 case htons(ETH_P_IPV6):
218 inner = ipv6_get_dsfield(ipv6_hdr(skb));
219 break;
220 default:
221 return 0;
222 }
223
224 return INET_ECN_decapsulate(skb, oiph->tos, inner);
225 }
226
IP6_ECN_decapsulate(const struct ipv6hdr * oipv6h,struct sk_buff * skb)227 static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h,
228 struct sk_buff *skb)
229 {
230 __u8 inner;
231
232 switch (skb_protocol(skb, true)) {
233 case htons(ETH_P_IP):
234 inner = ip_hdr(skb)->tos;
235 break;
236 case htons(ETH_P_IPV6):
237 inner = ipv6_get_dsfield(ipv6_hdr(skb));
238 break;
239 default:
240 return 0;
241 }
242
243 return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner);
244 }
245 #endif
246