tjh.dev
Linux kernel mirror (for testing)
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linux
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * IPv6 IOAM Lightweight Tunnel implementation
4 *
5 * Author:
6 * Justin Iurman <justin.iurman@uliege.be>
7 */
8
9#include <linux/kernel.h>
10#include <linux/skbuff.h>
11#include <linux/net.h>
12#include <linux/netlink.h>
13#include <linux/in6.h>
14#include <linux/ioam6.h>
15#include <linux/ioam6_iptunnel.h>
16#include <net/dst.h>
17#include <net/sock.h>
18#include <net/lwtunnel.h>
19#include <net/ioam6.h>
20
21#define IOAM6_MASK_SHORT_FIELDS 0xff100000
22#define IOAM6_MASK_WIDE_FIELDS 0xe00000
23
24struct ioam6_lwt_encap {
25 struct ipv6_hopopt_hdr eh;
26 u8 pad[2]; /* 2-octet padding for 4n-alignment */
27 struct ioam6_hdr ioamh;
28 struct ioam6_trace_hdr traceh;
29} __packed;
30
31struct ioam6_lwt {
32 struct ioam6_lwt_encap tuninfo;
33};
34
35static struct ioam6_lwt *ioam6_lwt_state(struct lwtunnel_state *lwt)
36{
37 return (struct ioam6_lwt *)lwt->data;
38}
39
40static struct ioam6_lwt_encap *ioam6_lwt_info(struct lwtunnel_state *lwt)
41{
42 return &ioam6_lwt_state(lwt)->tuninfo;
43}
44
45static struct ioam6_trace_hdr *ioam6_trace(struct lwtunnel_state *lwt)
46{
47 return &(ioam6_lwt_state(lwt)->tuninfo.traceh);
48}
49
50static const struct nla_policy ioam6_iptunnel_policy[IOAM6_IPTUNNEL_MAX + 1] = {
51 [IOAM6_IPTUNNEL_TRACE] = NLA_POLICY_EXACT_LEN(sizeof(struct ioam6_trace_hdr)),
52};
53
54static int nla_put_ioam6_trace(struct sk_buff *skb, int attrtype,
55 struct ioam6_trace_hdr *trace)
56{
57 struct ioam6_trace_hdr *data;
58 struct nlattr *nla;
59 int len;
60
61 len = sizeof(*trace);
62
63 nla = nla_reserve(skb, attrtype, len);
64 if (!nla)
65 return -EMSGSIZE;
66
67 data = nla_data(nla);
68 memcpy(data, trace, len);
69
70 return 0;
71}
72
73static bool ioam6_validate_trace_hdr(struct ioam6_trace_hdr *trace)
74{
75 u32 fields;
76
77 if (!trace->type_be32 || !trace->remlen ||
78 trace->remlen > IOAM6_TRACE_DATA_SIZE_MAX / 4)
79 return false;
80
81 trace->nodelen = 0;
82 fields = be32_to_cpu(trace->type_be32);
83
84 trace->nodelen += hweight32(fields & IOAM6_MASK_SHORT_FIELDS)
85 * (sizeof(__be32) / 4);
86 trace->nodelen += hweight32(fields & IOAM6_MASK_WIDE_FIELDS)
87 * (sizeof(__be64) / 4);
88
89 return true;
90}
91
92static int ioam6_build_state(struct net *net, struct nlattr *nla,
93 unsigned int family, const void *cfg,
94 struct lwtunnel_state **ts,
95 struct netlink_ext_ack *extack)
96{
97 struct nlattr *tb[IOAM6_IPTUNNEL_MAX + 1];
98 struct ioam6_lwt_encap *tuninfo;
99 struct ioam6_trace_hdr *trace;
100 struct lwtunnel_state *s;
101 int len_aligned;
102 int len, err;
103
104 if (family != AF_INET6)
105 return -EINVAL;
106
107 err = nla_parse_nested(tb, IOAM6_IPTUNNEL_MAX, nla,
108 ioam6_iptunnel_policy, extack);
109 if (err < 0)
110 return err;
111
112 if (!tb[IOAM6_IPTUNNEL_TRACE]) {
113 NL_SET_ERR_MSG(extack, "missing trace");
114 return -EINVAL;
115 }
116
117 trace = nla_data(tb[IOAM6_IPTUNNEL_TRACE]);
118 if (!ioam6_validate_trace_hdr(trace)) {
119 NL_SET_ERR_MSG_ATTR(extack, tb[IOAM6_IPTUNNEL_TRACE],
120 "invalid trace validation");
121 return -EINVAL;
122 }
123
124 len = sizeof(*tuninfo) + trace->remlen * 4;
125 len_aligned = ALIGN(len, 8);
126
127 s = lwtunnel_state_alloc(len_aligned);
128 if (!s)
129 return -ENOMEM;
130
131 tuninfo = ioam6_lwt_info(s);
132 tuninfo->eh.hdrlen = (len_aligned >> 3) - 1;
133 tuninfo->pad[0] = IPV6_TLV_PADN;
134 tuninfo->ioamh.type = IOAM6_TYPE_PREALLOC;
135 tuninfo->ioamh.opt_type = IPV6_TLV_IOAM;
136 tuninfo->ioamh.opt_len = sizeof(tuninfo->ioamh) - 2 + sizeof(*trace)
137 + trace->remlen * 4;
138
139 memcpy(&tuninfo->traceh, trace, sizeof(*trace));
140
141 len = len_aligned - len;
142 if (len == 1) {
143 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PAD1;
144 } else if (len > 0) {
145 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PADN;
146 tuninfo->traceh.data[trace->remlen * 4 + 1] = len - 2;
147 }
148
149 s->type = LWTUNNEL_ENCAP_IOAM6;
150 s->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
151
152 *ts = s;
153
154 return 0;
155}
156
157static int ioam6_do_inline(struct sk_buff *skb, struct ioam6_lwt_encap *tuninfo)
158{
159 struct ioam6_trace_hdr *trace;
160 struct ipv6hdr *oldhdr, *hdr;
161 struct ioam6_namespace *ns;
162 int hdrlen, err;
163
164 hdrlen = (tuninfo->eh.hdrlen + 1) << 3;
165
166 err = skb_cow_head(skb, hdrlen + skb->mac_len);
167 if (unlikely(err))
168 return err;
169
170 oldhdr = ipv6_hdr(skb);
171 skb_pull(skb, sizeof(*oldhdr));
172 skb_postpull_rcsum(skb, skb_network_header(skb), sizeof(*oldhdr));
173
174 skb_push(skb, sizeof(*oldhdr) + hdrlen);
175 skb_reset_network_header(skb);
176 skb_mac_header_rebuild(skb);
177
178 hdr = ipv6_hdr(skb);
179 memmove(hdr, oldhdr, sizeof(*oldhdr));
180 tuninfo->eh.nexthdr = hdr->nexthdr;
181
182 skb_set_transport_header(skb, sizeof(*hdr));
183 skb_postpush_rcsum(skb, hdr, sizeof(*hdr) + hdrlen);
184
185 memcpy(skb_transport_header(skb), (u8 *)tuninfo, hdrlen);
186
187 hdr->nexthdr = NEXTHDR_HOP;
188 hdr->payload_len = cpu_to_be16(skb->len - sizeof(*hdr));
189
190 trace = (struct ioam6_trace_hdr *)(skb_transport_header(skb)
191 + sizeof(struct ipv6_hopopt_hdr) + 2
192 + sizeof(struct ioam6_hdr));
193
194 ns = ioam6_namespace(dev_net(skb_dst(skb)->dev), trace->namespace_id);
195 if (ns)
196 ioam6_fill_trace_data(skb, ns, trace);
197
198 return 0;
199}
200
201static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
202{
203 struct lwtunnel_state *lwt = skb_dst(skb)->lwtstate;
204 int err = -EINVAL;
205
206 if (skb->protocol != htons(ETH_P_IPV6))
207 goto drop;
208
209 /* Only for packets we send and
210 * that do not contain a Hop-by-Hop yet
211 */
212 if (skb->dev || ipv6_hdr(skb)->nexthdr == NEXTHDR_HOP)
213 goto out;
214
215 err = ioam6_do_inline(skb, ioam6_lwt_info(lwt));
216 if (unlikely(err))
217 goto drop;
218
219 err = skb_cow_head(skb, LL_RESERVED_SPACE(skb_dst(skb)->dev));
220 if (unlikely(err))
221 goto drop;
222
223out:
224 return lwt->orig_output(net, sk, skb);
225
226drop:
227 kfree_skb(skb);
228 return err;
229}
230
231static int ioam6_fill_encap_info(struct sk_buff *skb,
232 struct lwtunnel_state *lwtstate)
233{
234 struct ioam6_trace_hdr *trace = ioam6_trace(lwtstate);
235
236 if (nla_put_ioam6_trace(skb, IOAM6_IPTUNNEL_TRACE, trace))
237 return -EMSGSIZE;
238
239 return 0;
240}
241
242static int ioam6_encap_nlsize(struct lwtunnel_state *lwtstate)
243{
244 struct ioam6_trace_hdr *trace = ioam6_trace(lwtstate);
245
246 return nla_total_size(sizeof(*trace));
247}
248
249static int ioam6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
250{
251 struct ioam6_trace_hdr *a_hdr = ioam6_trace(a);
252 struct ioam6_trace_hdr *b_hdr = ioam6_trace(b);
253
254 return (a_hdr->namespace_id != b_hdr->namespace_id);
255}
256
257static const struct lwtunnel_encap_ops ioam6_iptun_ops = {
258 .build_state = ioam6_build_state,
259 .output = ioam6_output,
260 .fill_encap = ioam6_fill_encap_info,
261 .get_encap_size = ioam6_encap_nlsize,
262 .cmp_encap = ioam6_encap_cmp,
263 .owner = THIS_MODULE,
264};
265
266int __init ioam6_iptunnel_init(void)
267{
268 return lwtunnel_encap_add_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
269}
270
271void ioam6_iptunnel_exit(void)
272{
273 lwtunnel_encap_del_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
274}