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
INET_ECN_set_ect1(struct sk_buff * skb)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 */
__INET_ECN_decapsulate(__u8 outer,__u8 inner,bool * set_ce)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
INET_ECN_decapsulate(struct sk_buff * skb,__u8 outer,__u8 inner)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
IP_ECN_decapsulate(const struct iphdr * oiph,struct sk_buff * skb)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
IP6_ECN_decapsulate(const struct ipv6hdr * oipv6h,struct sk_buff * skb)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
