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
INET_ECN_is_ce(__u8 dsfield)21 static inline int INET_ECN_is_ce(__u8 dsfield)
22 {
23 return (dsfield & INET_ECN_MASK) == INET_ECN_CE;
24 }
25
INET_ECN_is_not_ect(__u8 dsfield)26 static inline int INET_ECN_is_not_ect(__u8 dsfield)
27 {
28 return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT;
29 }
30
INET_ECN_is_capable(__u8 dsfield)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 */
INET_ECN_encapsulate(__u8 outer,__u8 inner)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
INET_ECN_xmit(struct sock * sk)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
INET_ECN_dontxmit(struct sock * sk)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
IP_ECN_set_ce(struct iphdr * iph)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
IP_ECN_clear(struct iphdr * iph)102 static inline void IP_ECN_clear(struct iphdr *iph)
103 {
104 iph->tos &= ~INET_ECN_MASK;
105 }
106
ipv4_copy_dscp(unsigned int dscp,struct iphdr * inner)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 */
IP6_ECN_set_ce(struct sk_buff * skb,struct ipv6hdr * iph)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
ipv6_copy_dscp(unsigned int dscp,struct ipv6hdr * inner)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
INET_ECN_set_ce(struct sk_buff * skb)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 */
INET_ECN_decapsulate(struct sk_buff * skb,__u8 outer,__u8 inner)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
IP_ECN_decapsulate(const struct iphdr * oiph,struct sk_buff * skb)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
IP6_ECN_decapsulate(const struct ipv6hdr * oipv6h,struct sk_buff * skb)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
