summaryrefslogtreecommitdiffstats
path: root/include/net/inet_ecn.h
blob: 0f0d1efe06ddcd1bcd67000bde1d7b88f0c74153 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _INET_ECN_H_
#define _INET_ECN_H_

#include <linux/ip.h>
#include <linux/skbuff.h>

#include <net/inet_sock.h>
#include <net/dsfield.h>

enum {
	INET_ECN_NOT_ECT = 0,
	INET_ECN_ECT_1 = 1,
	INET_ECN_ECT_0 = 2,
	INET_ECN_CE = 3,
	INET_ECN_MASK = 3,
};

extern int sysctl_tunnel_ecn_log;

static inline int INET_ECN_is_ce(__u8 dsfield)
{
	return (dsfield & INET_ECN_MASK) == INET_ECN_CE;
}

static inline int INET_ECN_is_not_ect(__u8 dsfield)
{
	return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT;
}

static inline int INET_ECN_is_capable(__u8 dsfield)
{
	return dsfield & INET_ECN_ECT_0;
}

/*
 * RFC 3168 9.1.1
 *  The full-functionality option for ECN encapsulation is to copy the
 *  ECN codepoint of the inside header to the outside header on
 *  encapsulation if the inside header is not-ECT or ECT, and to set the
 *  ECN codepoint of the outside header to ECT(0) if the ECN codepoint of
 *  the inside header is CE.
 */
static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner)
{
	outer &= ~INET_ECN_MASK;
	outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) :
					  INET_ECN_ECT_0;
	return outer;
}

static inline void INET_ECN_xmit(struct sock *sk)
{
	inet_sk(sk)->tos |= INET_ECN_ECT_0;
	if (inet6_sk(sk) != NULL)
		inet6_sk(sk)->tclass |= INET_ECN_ECT_0;
}

static inline void INET_ECN_dontxmit(struct sock *sk)
{
	inet_sk(sk)->tos &= ~INET_ECN_MASK;
	if (inet6_sk(sk) != NULL)
		inet6_sk(sk)->tclass &= ~INET_ECN_MASK;
}

#define IP6_ECN_flow_init(label) do {		\
      (label) &= ~htonl(INET_ECN_MASK << 20);	\
    } while (0)

#define	IP6_ECN_flow_xmit(sk, label) do {				\
	if (INET_ECN_is_capable(inet6_sk(sk)->tclass))			\
		(label) |= htonl(INET_ECN_ECT_0 << 20);			\
    } while (0)

static inline int IP_ECN_set_ce(struct iphdr *iph)
{
	u32 check = (__force u32)iph->check;
	u32 ecn = (iph->tos + 1) & INET_ECN_MASK;

	/*
	 * After the last operation we have (in binary):
	 * INET_ECN_NOT_ECT => 01
	 * INET_ECN_ECT_1   => 10
	 * INET_ECN_ECT_0   => 11
	 * INET_ECN_CE      => 00
	 */
	if (!(ecn & 2))
		return !ecn;

	/*
	 * The following gives us:
	 * INET_ECN_ECT_1 => check += htons(0xFFFD)
	 * INET_ECN_ECT_0 => check += htons(0xFFFE)
	 */
	check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn);

	iph->check = (__force __sum16)(check + (check>=0xFFFF));
	iph->tos |= INET_ECN_CE;
	return 1;
}

static inline int IP_ECN_set_ect1(struct iphdr *iph)
{
	u32 check = (__force u32)iph->check;

	if ((iph->tos & INET_ECN_MASK) != INET_ECN_ECT_0)
		return 0;

	check += (__force u16)htons(0x100);

	iph->check = (__force __sum16)(check + (check>=0xFFFF));
	iph->tos ^= INET_ECN_MASK;
	return 1;
}

static inline void IP_ECN_clear(struct iphdr *iph)
{
	iph->tos &= ~INET_ECN_MASK;
}

static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner)
{
	dscp &= ~INET_ECN_MASK;
	ipv4_change_dsfield(inner, INET_ECN_MASK, dscp);
}

struct ipv6hdr;

/* Note:
 * IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE,
 * meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE
 * In IPv6 case, no checksum compensates the change in IPv6 header,
 * so we have to update skb->csum.
 */
static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph)
{
	__be32 from, to;

	if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))
		return 0;

	from = *(__be32 *)iph;
	to = from | htonl(INET_ECN_CE << 20);
	*(__be32 *)iph = to;
	if (skb->ip_summed == CHECKSUM_COMPLETE)
		skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from),
				     (__force __wsum)to);
	return 1;
}

static inline int IP6_ECN_set_ect1(struct sk_buff *skb, struct ipv6hdr *iph)
{
	__be32 from, to;

	if ((ipv6_get_dsfield(iph) & INET_ECN_MASK) != INET_ECN_ECT_0)
		return 0;

	from = *(__be32 *)iph;
	to = from ^ htonl(INET_ECN_MASK << 20);
	*(__be32 *)iph = to;
	if (skb->ip_summed == CHECKSUM_COMPLETE)
		skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from),
				     (__force __wsum)to);
	return 1;
}

static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner)
{
	dscp &= ~INET_ECN_MASK;
	ipv6_change_dsfield(inner, INET_ECN_MASK, dscp);
}

static inline int INET_ECN_set_ce(struct sk_buff *skb)
{
	switch (skb->protocol) {
	case cpu_to_be16(ETH_P_IP):
		if (skb_network_header(skb) + sizeof(struct iphdr) <=
		    skb_tail_pointer(skb))
			return IP_ECN_set_ce(ip_hdr(skb));
		break;

	case cpu_to_be16(ETH_P_IPV6):
		if (skb_network_header(skb) + sizeof(struct ipv6hdr) <=
		    skb_tail_pointer(skb))
			return IP6_ECN_set_ce(skb, ipv6_hdr(skb));
		break;
	}

	return 0;
}

static inline int INET_ECN_set_ect1(struct sk_buff *skb)
{
	switch (skb->protocol) {
	case cpu_to_be16(ETH_P_IP):
		if (skb_network_header(skb) + sizeof(struct iphdr) <=
		    skb_tail_pointer(skb))
			return IP_ECN_set_ect1(ip_hdr(skb));
		break;

	case cpu_to_be16(ETH_P_IPV6):
		if (skb_network_header(skb) + sizeof(struct ipv6hdr) <=
		    skb_tail_pointer(skb))
			return IP6_ECN_set_ect1(skb, ipv6_hdr(skb));
		break;
	}

	return 0;
}

/*
 * RFC 6040 4.2
 *  To decapsulate the inner header at the tunnel egress, a compliant
 *  tunnel egress MUST set the outgoing ECN field to the codepoint at the
 *  intersection of the appropriate arriving inner header (row) and outer
 *  header (column) in Figure 4
 *
 *      +---------+------------------------------------------------+
 *      |Arriving |            Arriving Outer Header               |
 *      |   Inner +---------+------------+------------+------------+
 *      |  Header | Not-ECT | ECT(0)     | ECT(1)     |     CE     |
 *      +---------+---------+------------+------------+------------+
 *      | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)|
 *      |  ECT(0) |  ECT(0) | ECT(0)     | ECT(1)     |     CE     |
 *      |  ECT(1) |  ECT(1) | ECT(1) (!) | ECT(1)     |     CE     |
 *      |    CE   |      CE |     CE     |     CE(!!!)|     CE     |
 *      +---------+---------+------------+------------+------------+
 *
 *             Figure 4: New IP in IP Decapsulation Behaviour
 *
 *  returns 0 on success
 *          1 if something is broken and should be logged (!!! above)
 *          2 if packet should be dropped
 */
static inline int __INET_ECN_decapsulate(__u8 outer, __u8 inner, bool *set_ce)
{
	if (INET_ECN_is_not_ect(inner)) {
		switch (outer & INET_ECN_MASK) {
		case INET_ECN_NOT_ECT:
			return 0;
		case INET_ECN_ECT_0:
		case INET_ECN_ECT_1:
			return 1;
		case INET_ECN_CE:
			return 2;
		}
	}

	*set_ce = INET_ECN_is_ce(outer);
	return 0;
}

static inline int INET_ECN_decapsulate(struct sk_buff *skb,
				       __u8 outer, __u8 inner)
{
	bool set_ce = false;
	int rc;

	rc = __INET_ECN_decapsulate(outer, inner, &set_ce);
	if (!rc) {
		if (set_ce)
			INET_ECN_set_ce(skb);
		else if ((outer & INET_ECN_MASK) == INET_ECN_ECT_1)
			INET_ECN_set_ect1(skb);
	}

	return rc;
}

static inline int IP_ECN_decapsulate(const struct iphdr *oiph,
				     struct sk_buff *skb)
{
	__u8 inner;

	if (skb->protocol == htons(ETH_P_IP))
		inner = ip_hdr(skb)->tos;
	else if (skb->protocol == htons(ETH_P_IPV6))
		inner = ipv6_get_dsfield(ipv6_hdr(skb));
	else
		return 0;

	return INET_ECN_decapsulate(skb, oiph->tos, inner);
}

static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h,
				      struct sk_buff *skb)
{
	__u8 inner;

	if (skb->protocol == htons(ETH_P_IP))
		inner = ip_hdr(skb)->tos;
	else if (skb->protocol == htons(ETH_P_IPV6))
		inner = ipv6_get_dsfield(ipv6_hdr(skb));
	else
		return 0;

	return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner);
}
#endif