xref: /linux/net/ipv6/ila/ila_lwt.c (revision 36ec807b627b4c0a0a382f0ae48eac7187d14b2b)
1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/errno.h>
3 #include <linux/ip.h>
4 #include <linux/kernel.h>
5 #include <linux/module.h>
6 #include <linux/skbuff.h>
7 #include <linux/socket.h>
8 #include <linux/types.h>
9 #include <net/checksum.h>
10 #include <net/dst_cache.h>
11 #include <net/ip.h>
12 #include <net/ip6_fib.h>
13 #include <net/ip6_route.h>
14 #include <net/lwtunnel.h>
15 #include <net/protocol.h>
16 #include <uapi/linux/ila.h>
17 #include "ila.h"
18 
19 struct ila_lwt {
20 	struct ila_params p;
21 	struct dst_cache dst_cache;
22 	u32 connected : 1;
23 	u32 lwt_output : 1;
24 };
25 
26 static inline struct ila_lwt *ila_lwt_lwtunnel(
27 	struct lwtunnel_state *lwt)
28 {
29 	return (struct ila_lwt *)lwt->data;
30 }
31 
32 static inline struct ila_params *ila_params_lwtunnel(
33 	struct lwtunnel_state *lwt)
34 {
35 	return &ila_lwt_lwtunnel(lwt)->p;
36 }
37 
38 static int ila_output(struct net *net, struct sock *sk, struct sk_buff *skb)
39 {
40 	struct dst_entry *orig_dst = skb_dst(skb);
41 	struct rt6_info *rt = dst_rt6_info(orig_dst);
42 	struct ila_lwt *ilwt = ila_lwt_lwtunnel(orig_dst->lwtstate);
43 	struct dst_entry *dst;
44 	int err = -EINVAL;
45 
46 	if (skb->protocol != htons(ETH_P_IPV6))
47 		goto drop;
48 
49 	if (ilwt->lwt_output)
50 		ila_update_ipv6_locator(skb,
51 					ila_params_lwtunnel(orig_dst->lwtstate),
52 					true);
53 
54 	if (rt->rt6i_flags & (RTF_GATEWAY | RTF_CACHE)) {
55 		/* Already have a next hop address in route, no need for
56 		 * dest cache route.
57 		 */
58 		return orig_dst->lwtstate->orig_output(net, sk, skb);
59 	}
60 
61 	local_bh_disable();
62 	dst = dst_cache_get(&ilwt->dst_cache);
63 	local_bh_enable();
64 	if (unlikely(!dst)) {
65 		struct ipv6hdr *ip6h = ipv6_hdr(skb);
66 		struct flowi6 fl6;
67 
68 		/* Lookup a route for the new destination. Take into
69 		 * account that the base route may already have a gateway.
70 		 */
71 
72 		memset(&fl6, 0, sizeof(fl6));
73 		fl6.flowi6_oif = orig_dst->dev->ifindex;
74 		fl6.flowi6_iif = LOOPBACK_IFINDEX;
75 		fl6.daddr = *rt6_nexthop(dst_rt6_info(orig_dst),
76 					 &ip6h->daddr);
77 
78 		dst = ip6_route_output(net, NULL, &fl6);
79 		if (dst->error) {
80 			err = -EHOSTUNREACH;
81 			dst_release(dst);
82 			goto drop;
83 		}
84 
85 		dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
86 		if (IS_ERR(dst)) {
87 			err = PTR_ERR(dst);
88 			goto drop;
89 		}
90 
91 		if (ilwt->connected) {
92 			local_bh_disable();
93 			dst_cache_set_ip6(&ilwt->dst_cache, dst, &fl6.saddr);
94 			local_bh_enable();
95 		}
96 	}
97 
98 	skb_dst_set(skb, dst);
99 	return dst_output(net, sk, skb);
100 
101 drop:
102 	kfree_skb(skb);
103 	return err;
104 }
105 
106 static int ila_input(struct sk_buff *skb)
107 {
108 	struct dst_entry *dst = skb_dst(skb);
109 	struct ila_lwt *ilwt = ila_lwt_lwtunnel(dst->lwtstate);
110 
111 	if (skb->protocol != htons(ETH_P_IPV6))
112 		goto drop;
113 
114 	if (!ilwt->lwt_output)
115 		ila_update_ipv6_locator(skb,
116 					ila_params_lwtunnel(dst->lwtstate),
117 					false);
118 
119 	return dst->lwtstate->orig_input(skb);
120 
121 drop:
122 	kfree_skb(skb);
123 	return -EINVAL;
124 }
125 
126 static const struct nla_policy ila_nl_policy[ILA_ATTR_MAX + 1] = {
127 	[ILA_ATTR_LOCATOR] = { .type = NLA_U64, },
128 	[ILA_ATTR_CSUM_MODE] = { .type = NLA_U8, },
129 	[ILA_ATTR_IDENT_TYPE] = { .type = NLA_U8, },
130 	[ILA_ATTR_HOOK_TYPE] = { .type = NLA_U8, },
131 };
132 
133 static int ila_build_state(struct net *net, struct nlattr *nla,
134 			   unsigned int family, const void *cfg,
135 			   struct lwtunnel_state **ts,
136 			   struct netlink_ext_ack *extack)
137 {
138 	struct ila_lwt *ilwt;
139 	struct ila_params *p;
140 	struct nlattr *tb[ILA_ATTR_MAX + 1];
141 	struct lwtunnel_state *newts;
142 	const struct fib6_config *cfg6 = cfg;
143 	struct ila_addr *iaddr;
144 	u8 ident_type = ILA_ATYPE_USE_FORMAT;
145 	u8 hook_type = ILA_HOOK_ROUTE_OUTPUT;
146 	u8 csum_mode = ILA_CSUM_NO_ACTION;
147 	bool lwt_output = true;
148 	u8 eff_ident_type;
149 	int ret;
150 
151 	if (family != AF_INET6)
152 		return -EINVAL;
153 
154 	ret = nla_parse_nested_deprecated(tb, ILA_ATTR_MAX, nla,
155 					  ila_nl_policy, extack);
156 	if (ret < 0)
157 		return ret;
158 
159 	if (!tb[ILA_ATTR_LOCATOR])
160 		return -EINVAL;
161 
162 	iaddr = (struct ila_addr *)&cfg6->fc_dst;
163 
164 	if (tb[ILA_ATTR_IDENT_TYPE])
165 		ident_type = nla_get_u8(tb[ILA_ATTR_IDENT_TYPE]);
166 
167 	if (ident_type == ILA_ATYPE_USE_FORMAT) {
168 		/* Infer identifier type from type field in formatted
169 		 * identifier.
170 		 */
171 
172 		if (cfg6->fc_dst_len < 8 * sizeof(struct ila_locator) + 3) {
173 			/* Need to have full locator and at least type field
174 			 * included in destination
175 			 */
176 			return -EINVAL;
177 		}
178 
179 		eff_ident_type = iaddr->ident.type;
180 	} else {
181 		eff_ident_type = ident_type;
182 	}
183 
184 	switch (eff_ident_type) {
185 	case ILA_ATYPE_IID:
186 		/* Don't allow ILA for IID type */
187 		return -EINVAL;
188 	case ILA_ATYPE_LUID:
189 		break;
190 	case ILA_ATYPE_VIRT_V4:
191 	case ILA_ATYPE_VIRT_UNI_V6:
192 	case ILA_ATYPE_VIRT_MULTI_V6:
193 	case ILA_ATYPE_NONLOCAL_ADDR:
194 		/* These ILA formats are not supported yet. */
195 	default:
196 		return -EINVAL;
197 	}
198 
199 	if (tb[ILA_ATTR_HOOK_TYPE])
200 		hook_type = nla_get_u8(tb[ILA_ATTR_HOOK_TYPE]);
201 
202 	switch (hook_type) {
203 	case ILA_HOOK_ROUTE_OUTPUT:
204 		lwt_output = true;
205 		break;
206 	case ILA_HOOK_ROUTE_INPUT:
207 		lwt_output = false;
208 		break;
209 	default:
210 		return -EINVAL;
211 	}
212 
213 	if (tb[ILA_ATTR_CSUM_MODE])
214 		csum_mode = nla_get_u8(tb[ILA_ATTR_CSUM_MODE]);
215 
216 	if (csum_mode == ILA_CSUM_NEUTRAL_MAP &&
217 	    ila_csum_neutral_set(iaddr->ident)) {
218 		/* Don't allow translation if checksum neutral bit is
219 		 * configured and it's set in the SIR address.
220 		 */
221 		return -EINVAL;
222 	}
223 
224 	newts = lwtunnel_state_alloc(sizeof(*ilwt));
225 	if (!newts)
226 		return -ENOMEM;
227 
228 	ilwt = ila_lwt_lwtunnel(newts);
229 	ret = dst_cache_init(&ilwt->dst_cache, GFP_ATOMIC);
230 	if (ret) {
231 		kfree(newts);
232 		return ret;
233 	}
234 
235 	ilwt->lwt_output = !!lwt_output;
236 
237 	p = ila_params_lwtunnel(newts);
238 
239 	p->csum_mode = csum_mode;
240 	p->ident_type = ident_type;
241 	p->locator.v64 = (__force __be64)nla_get_u64(tb[ILA_ATTR_LOCATOR]);
242 
243 	/* Precompute checksum difference for translation since we
244 	 * know both the old locator and the new one.
245 	 */
246 	p->locator_match = iaddr->loc;
247 
248 	ila_init_saved_csum(p);
249 
250 	newts->type = LWTUNNEL_ENCAP_ILA;
251 	newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT |
252 			LWTUNNEL_STATE_INPUT_REDIRECT;
253 
254 	if (cfg6->fc_dst_len == 8 * sizeof(struct in6_addr))
255 		ilwt->connected = 1;
256 
257 	*ts = newts;
258 
259 	return 0;
260 }
261 
262 static void ila_destroy_state(struct lwtunnel_state *lwt)
263 {
264 	dst_cache_destroy(&ila_lwt_lwtunnel(lwt)->dst_cache);
265 }
266 
267 static int ila_fill_encap_info(struct sk_buff *skb,
268 			       struct lwtunnel_state *lwtstate)
269 {
270 	struct ila_params *p = ila_params_lwtunnel(lwtstate);
271 	struct ila_lwt *ilwt = ila_lwt_lwtunnel(lwtstate);
272 
273 	if (nla_put_u64_64bit(skb, ILA_ATTR_LOCATOR, (__force u64)p->locator.v64,
274 			      ILA_ATTR_PAD))
275 		goto nla_put_failure;
276 
277 	if (nla_put_u8(skb, ILA_ATTR_CSUM_MODE, (__force u8)p->csum_mode))
278 		goto nla_put_failure;
279 
280 	if (nla_put_u8(skb, ILA_ATTR_IDENT_TYPE, (__force u8)p->ident_type))
281 		goto nla_put_failure;
282 
283 	if (nla_put_u8(skb, ILA_ATTR_HOOK_TYPE,
284 		       ilwt->lwt_output ? ILA_HOOK_ROUTE_OUTPUT :
285 					  ILA_HOOK_ROUTE_INPUT))
286 		goto nla_put_failure;
287 
288 	return 0;
289 
290 nla_put_failure:
291 	return -EMSGSIZE;
292 }
293 
294 static int ila_encap_nlsize(struct lwtunnel_state *lwtstate)
295 {
296 	return nla_total_size_64bit(sizeof(u64)) + /* ILA_ATTR_LOCATOR */
297 	       nla_total_size(sizeof(u8)) +        /* ILA_ATTR_CSUM_MODE */
298 	       nla_total_size(sizeof(u8)) +        /* ILA_ATTR_IDENT_TYPE */
299 	       nla_total_size(sizeof(u8)) +        /* ILA_ATTR_HOOK_TYPE */
300 	       0;
301 }
302 
303 static int ila_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
304 {
305 	struct ila_params *a_p = ila_params_lwtunnel(a);
306 	struct ila_params *b_p = ila_params_lwtunnel(b);
307 
308 	return (a_p->locator.v64 != b_p->locator.v64);
309 }
310 
311 static const struct lwtunnel_encap_ops ila_encap_ops = {
312 	.build_state = ila_build_state,
313 	.destroy_state = ila_destroy_state,
314 	.output = ila_output,
315 	.input = ila_input,
316 	.fill_encap = ila_fill_encap_info,
317 	.get_encap_size = ila_encap_nlsize,
318 	.cmp_encap = ila_encap_cmp,
319 	.owner = THIS_MODULE,
320 };
321 
322 int ila_lwt_init(void)
323 {
324 	return lwtunnel_encap_add_ops(&ila_encap_ops, LWTUNNEL_ENCAP_ILA);
325 }
326 
327 void ila_lwt_fini(void)
328 {
329 	lwtunnel_encap_del_ops(&ila_encap_ops, LWTUNNEL_ENCAP_ILA);
330 }
331