xref: /linux/net/netfilter/nft_flow_offload.c (revision e91c37f1) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/kernel.h>
3 #include <linux/module.h>
4 #include <linux/init.h>
5 #include <linux/netlink.h>
6 #include <linux/netfilter.h>
7 #include <linux/workqueue.h>
8 #include <linux/spinlock.h>
9 #include <linux/netfilter/nf_conntrack_common.h>
10 #include <linux/netfilter/nf_tables.h>
11 #include <net/ip.h> /* for ipv4 options. */
12 #include <net/netfilter/nf_tables.h>
13 #include <net/netfilter/nf_tables_core.h>
14 #include <net/netfilter/nf_conntrack_core.h>
15 #include <net/netfilter/nf_conntrack_extend.h>
16 #include <net/netfilter/nf_flow_table.h>
17 
18 struct nft_flow_offload {
19 	struct nft_flowtable	*flowtable;
20 };
21 
22 static enum flow_offload_xmit_type nft_xmit_type(struct dst_entry *dst)
23 {
24 	if (dst_xfrm(dst))
25 		return FLOW_OFFLOAD_XMIT_XFRM;
26 
27 	return FLOW_OFFLOAD_XMIT_NEIGH;
28 }
29 
30 static void nft_default_forward_path(struct nf_flow_route *route,
31 				     struct dst_entry *dst_cache,
32 				     enum ip_conntrack_dir dir)
33 {
34 	route->tuple[!dir].in.ifindex	= dst_cache->dev->ifindex;
35 	route->tuple[dir].dst		= dst_cache;
36 	route->tuple[dir].xmit_type	= nft_xmit_type(dst_cache);
37 }
38 
39 static bool nft_is_valid_ether_device(const struct net_device *dev)
40 {
41 	if (!dev || (dev->flags & IFF_LOOPBACK) || dev->type != ARPHRD_ETHER ||
42 	    dev->addr_len != ETH_ALEN || !is_valid_ether_addr(dev->dev_addr))
43 		return false;
44 
45 	return true;
46 }
47 
48 static int nft_dev_fill_forward_path(const struct nf_flow_route *route,
49 				     const struct dst_entry *dst_cache,
50 				     const struct nf_conn *ct,
51 				     enum ip_conntrack_dir dir, u8 *ha,
52 				     struct net_device_path_stack *stack)
53 {
54 	const void *daddr = &ct->tuplehash[!dir].tuple.src.u3;
55 	struct net_device *dev = dst_cache->dev;
56 	struct neighbour *n;
57 	u8 nud_state;
58 
59 	if (!nft_is_valid_ether_device(dev))
60 		goto out;
61 
62 	n = dst_neigh_lookup(dst_cache, daddr);
63 	if (!n)
64 		return -1;
65 
66 	read_lock_bh(&n->lock);
67 	nud_state = n->nud_state;
68 	ether_addr_copy(ha, n->ha);
69 	read_unlock_bh(&n->lock);
70 	neigh_release(n);
71 
72 	if (!(nud_state & NUD_VALID))
73 		return -1;
74 
75 out:
76 	return dev_fill_forward_path(dev, ha, stack);
77 }
78 
79 struct nft_forward_info {
80 	const struct net_device *indev;
81 	const struct net_device *outdev;
82 	const struct net_device *hw_outdev;
83 	struct id {
84 		__u16	id;
85 		__be16	proto;
86 	} encap[NF_FLOW_TABLE_ENCAP_MAX];
87 	u8 num_encaps;
88 	u8 ingress_vlans;
89 	u8 h_source[ETH_ALEN];
90 	u8 h_dest[ETH_ALEN];
91 	enum flow_offload_xmit_type xmit_type;
92 };
93 
94 static void nft_dev_path_info(const struct net_device_path_stack *stack,
95 			      struct nft_forward_info *info,
96 			      unsigned char *ha, struct nf_flowtable *flowtable)
97 {
98 	const struct net_device_path *path;
99 	int i;
100 
101 	memcpy(info->h_dest, ha, ETH_ALEN);
102 
103 	for (i = 0; i < stack->num_paths; i++) {
104 		path = &stack->path[i];
105 		switch (path->type) {
106 		case DEV_PATH_ETHERNET:
107 		case DEV_PATH_DSA:
108 		case DEV_PATH_VLAN:
109 		case DEV_PATH_PPPOE:
110 			info->indev = path->dev;
111 			if (is_zero_ether_addr(info->h_source))
112 				memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
113 
114 			if (path->type == DEV_PATH_ETHERNET)
115 				break;
116 			if (path->type == DEV_PATH_DSA) {
117 				i = stack->num_paths;
118 				break;
119 			}
120 
121 			/* DEV_PATH_VLAN and DEV_PATH_PPPOE */
122 			if (info->num_encaps >= NF_FLOW_TABLE_ENCAP_MAX) {
123 				info->indev = NULL;
124 				break;
125 			}
126 			if (!info->outdev)
127 				info->outdev = path->dev;
128 			info->encap[info->num_encaps].id = path->encap.id;
129 			info->encap[info->num_encaps].proto = path->encap.proto;
130 			info->num_encaps++;
131 			if (path->type == DEV_PATH_PPPOE)
132 				memcpy(info->h_dest, path->encap.h_dest, ETH_ALEN);
133 			break;
134 		case DEV_PATH_BRIDGE:
135 			if (is_zero_ether_addr(info->h_source))
136 				memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
137 
138 			switch (path->bridge.vlan_mode) {
139 			case DEV_PATH_BR_VLAN_UNTAG_HW:
140 				info->ingress_vlans |= BIT(info->num_encaps - 1);
141 				break;
142 			case DEV_PATH_BR_VLAN_TAG:
143 				info->encap[info->num_encaps].id = path->bridge.vlan_id;
144 				info->encap[info->num_encaps].proto = path->bridge.vlan_proto;
145 				info->num_encaps++;
146 				break;
147 			case DEV_PATH_BR_VLAN_UNTAG:
148 				info->num_encaps--;
149 				break;
150 			case DEV_PATH_BR_VLAN_KEEP:
151 				break;
152 			}
153 			info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
154 			break;
155 		default:
156 			info->indev = NULL;
157 			break;
158 		}
159 	}
160 	if (!info->outdev)
161 		info->outdev = info->indev;
162 
163 	info->hw_outdev = info->indev;
164 
165 	if (nf_flowtable_hw_offload(flowtable) &&
166 	    nft_is_valid_ether_device(info->indev))
167 		info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
168 }
169 
170 static bool nft_flowtable_find_dev(const struct net_device *dev,
171 				   struct nft_flowtable *ft)
172 {
173 	struct nft_hook *hook;
174 	bool found = false;
175 
176 	list_for_each_entry_rcu(hook, &ft->hook_list, list) {
177 		if (hook->ops.dev != dev)
178 			continue;
179 
180 		found = true;
181 		break;
182 	}
183 
184 	return found;
185 }
186 
187 static void nft_dev_forward_path(struct nf_flow_route *route,
188 				 const struct nf_conn *ct,
189 				 enum ip_conntrack_dir dir,
190 				 struct nft_flowtable *ft)
191 {
192 	const struct dst_entry *dst = route->tuple[dir].dst;
193 	struct net_device_path_stack stack;
194 	struct nft_forward_info info = {};
195 	unsigned char ha[ETH_ALEN];
196 	int i;
197 
198 	if (nft_dev_fill_forward_path(route, dst, ct, dir, ha, &stack) >= 0)
199 		nft_dev_path_info(&stack, &info, ha, &ft->data);
200 
201 	if (!info.indev || !nft_flowtable_find_dev(info.indev, ft))
202 		return;
203 
204 	route->tuple[!dir].in.ifindex = info.indev->ifindex;
205 	for (i = 0; i < info.num_encaps; i++) {
206 		route->tuple[!dir].in.encap[i].id = info.encap[i].id;
207 		route->tuple[!dir].in.encap[i].proto = info.encap[i].proto;
208 	}
209 	route->tuple[!dir].in.num_encaps = info.num_encaps;
210 	route->tuple[!dir].in.ingress_vlans = info.ingress_vlans;
211 
212 	if (info.xmit_type == FLOW_OFFLOAD_XMIT_DIRECT) {
213 		memcpy(route->tuple[dir].out.h_source, info.h_source, ETH_ALEN);
214 		memcpy(route->tuple[dir].out.h_dest, info.h_dest, ETH_ALEN);
215 		route->tuple[dir].out.ifindex = info.outdev->ifindex;
216 		route->tuple[dir].out.hw_ifindex = info.hw_outdev->ifindex;
217 		route->tuple[dir].xmit_type = info.xmit_type;
218 	}
219 }
220 
221 static int nft_flow_route(const struct nft_pktinfo *pkt,
222 			  const struct nf_conn *ct,
223 			  struct nf_flow_route *route,
224 			  enum ip_conntrack_dir dir,
225 			  struct nft_flowtable *ft)
226 {
227 	struct dst_entry *this_dst = skb_dst(pkt->skb);
228 	struct dst_entry *other_dst = NULL;
229 	struct flowi fl;
230 
231 	memset(&fl, 0, sizeof(fl));
232 	switch (nft_pf(pkt)) {
233 	case NFPROTO_IPV4:
234 		fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
235 		fl.u.ip4.saddr = ct->tuplehash[!dir].tuple.src.u3.ip;
236 		fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
237 		fl.u.ip4.flowi4_iif = this_dst->dev->ifindex;
238 		fl.u.ip4.flowi4_tos = RT_TOS(ip_hdr(pkt->skb)->tos);
239 		fl.u.ip4.flowi4_mark = pkt->skb->mark;
240 		fl.u.ip4.flowi4_flags = FLOWI_FLAG_ANYSRC;
241 		break;
242 	case NFPROTO_IPV6:
243 		fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
244 		fl.u.ip6.saddr = ct->tuplehash[!dir].tuple.src.u3.in6;
245 		fl.u.ip6.flowi6_oif = nft_in(pkt)->ifindex;
246 		fl.u.ip6.flowi6_iif = this_dst->dev->ifindex;
247 		fl.u.ip6.flowlabel = ip6_flowinfo(ipv6_hdr(pkt->skb));
248 		fl.u.ip6.flowi6_mark = pkt->skb->mark;
249 		fl.u.ip6.flowi6_flags = FLOWI_FLAG_ANYSRC;
250 		break;
251 	}
252 
253 	if (!dst_hold_safe(this_dst))
254 		return -ENOENT;
255 
256 	nf_route(nft_net(pkt), &other_dst, &fl, false, nft_pf(pkt));
257 	if (!other_dst) {
258 		dst_release(this_dst);
259 		return -ENOENT;
260 	}
261 
262 	nft_default_forward_path(route, this_dst, dir);
263 	nft_default_forward_path(route, other_dst, !dir);
264 
265 	if (route->tuple[dir].xmit_type	== FLOW_OFFLOAD_XMIT_NEIGH &&
266 	    route->tuple[!dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH) {
267 		nft_dev_forward_path(route, ct, dir, ft);
268 		nft_dev_forward_path(route, ct, !dir, ft);
269 	}
270 
271 	return 0;
272 }
273 
274 static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
275 {
276 	if (skb_sec_path(skb))
277 		return true;
278 
279 	if (family == NFPROTO_IPV4) {
280 		const struct ip_options *opt;
281 
282 		opt = &(IPCB(skb)->opt);
283 
284 		if (unlikely(opt->optlen))
285 			return true;
286 	}
287 
288 	return false;
289 }
290 
291 static void nft_flow_offload_eval(const struct nft_expr *expr,
292 				  struct nft_regs *regs,
293 				  const struct nft_pktinfo *pkt)
294 {
295 	struct nft_flow_offload *priv = nft_expr_priv(expr);
296 	struct nf_flowtable *flowtable = &priv->flowtable->data;
297 	struct tcphdr _tcph, *tcph = NULL;
298 	struct nf_flow_route route = {};
299 	enum ip_conntrack_info ctinfo;
300 	struct flow_offload *flow;
301 	enum ip_conntrack_dir dir;
302 	struct nf_conn *ct;
303 	int ret;
304 
305 	if (nft_flow_offload_skip(pkt->skb, nft_pf(pkt)))
306 		goto out;
307 
308 	ct = nf_ct_get(pkt->skb, &ctinfo);
309 	if (!ct)
310 		goto out;
311 
312 	switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
313 	case IPPROTO_TCP:
314 		tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt),
315 					  sizeof(_tcph), &_tcph);
316 		if (unlikely(!tcph || tcph->fin || tcph->rst ||
317 			     !nf_conntrack_tcp_established(ct)))
318 			goto out;
319 		break;
320 	case IPPROTO_UDP:
321 		break;
322 #ifdef CONFIG_NF_CT_PROTO_GRE
323 	case IPPROTO_GRE: {
324 		struct nf_conntrack_tuple *tuple;
325 
326 		if (ct->status & IPS_NAT_MASK)
327 			goto out;
328 		tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
329 		/* No support for GRE v1 */
330 		if (tuple->src.u.gre.key || tuple->dst.u.gre.key)
331 			goto out;
332 		break;
333 	}
334 #endif
335 	default:
336 		goto out;
337 	}
338 
339 	if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
340 	    ct->status & (IPS_SEQ_ADJUST | IPS_NAT_CLASH))
341 		goto out;
342 
343 	if (!nf_ct_is_confirmed(ct))
344 		goto out;
345 
346 	if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
347 		goto out;
348 
349 	dir = CTINFO2DIR(ctinfo);
350 	if (nft_flow_route(pkt, ct, &route, dir, priv->flowtable) < 0)
351 		goto err_flow_route;
352 
353 	flow = flow_offload_alloc(ct);
354 	if (!flow)
355 		goto err_flow_alloc;
356 
357 	flow_offload_route_init(flow, &route);
358 
359 	if (tcph) {
360 		ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
361 		ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
362 	}
363 
364 	ret = flow_offload_add(flowtable, flow);
365 	if (ret < 0)
366 		goto err_flow_add;
367 
368 	return;
369 
370 err_flow_add:
371 	flow_offload_free(flow);
372 err_flow_alloc:
373 	dst_release(route.tuple[dir].dst);
374 	dst_release(route.tuple[!dir].dst);
375 err_flow_route:
376 	clear_bit(IPS_OFFLOAD_BIT, &ct->status);
377 out:
378 	regs->verdict.code = NFT_BREAK;
379 }
380 
381 static int nft_flow_offload_validate(const struct nft_ctx *ctx,
382 				     const struct nft_expr *expr,
383 				     const struct nft_data **data)
384 {
385 	unsigned int hook_mask = (1 << NF_INET_FORWARD);
386 
387 	if (ctx->family != NFPROTO_IPV4 &&
388 	    ctx->family != NFPROTO_IPV6 &&
389 	    ctx->family != NFPROTO_INET)
390 		return -EOPNOTSUPP;
391 
392 	return nft_chain_validate_hooks(ctx->chain, hook_mask);
393 }
394 
395 static const struct nla_policy nft_flow_offload_policy[NFTA_FLOW_MAX + 1] = {
396 	[NFTA_FLOW_TABLE_NAME]	= { .type = NLA_STRING,
397 				    .len = NFT_NAME_MAXLEN - 1 },
398 };
399 
400 static int nft_flow_offload_init(const struct nft_ctx *ctx,
401 				 const struct nft_expr *expr,
402 				 const struct nlattr * const tb[])
403 {
404 	struct nft_flow_offload *priv = nft_expr_priv(expr);
405 	u8 genmask = nft_genmask_next(ctx->net);
406 	struct nft_flowtable *flowtable;
407 
408 	if (!tb[NFTA_FLOW_TABLE_NAME])
409 		return -EINVAL;
410 
411 	flowtable = nft_flowtable_lookup(ctx->table, tb[NFTA_FLOW_TABLE_NAME],
412 					 genmask);
413 	if (IS_ERR(flowtable))
414 		return PTR_ERR(flowtable);
415 
416 	if (!nft_use_inc(&flowtable->use))
417 		return -EMFILE;
418 
419 	priv->flowtable = flowtable;
420 
421 	return nf_ct_netns_get(ctx->net, ctx->family);
422 }
423 
424 static void nft_flow_offload_deactivate(const struct nft_ctx *ctx,
425 					const struct nft_expr *expr,
426 					enum nft_trans_phase phase)
427 {
428 	struct nft_flow_offload *priv = nft_expr_priv(expr);
429 
430 	nf_tables_deactivate_flowtable(ctx, priv->flowtable, phase);
431 }
432 
433 static void nft_flow_offload_activate(const struct nft_ctx *ctx,
434 				      const struct nft_expr *expr)
435 {
436 	struct nft_flow_offload *priv = nft_expr_priv(expr);
437 
438 	nft_use_inc_restore(&priv->flowtable->use);
439 }
440 
441 static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
442 				     const struct nft_expr *expr)
443 {
444 	nf_ct_netns_put(ctx->net, ctx->family);
445 }
446 
447 static int nft_flow_offload_dump(struct sk_buff *skb,
448 				 const struct nft_expr *expr, bool reset)
449 {
450 	struct nft_flow_offload *priv = nft_expr_priv(expr);
451 
452 	if (nla_put_string(skb, NFTA_FLOW_TABLE_NAME, priv->flowtable->name))
453 		goto nla_put_failure;
454 
455 	return 0;
456 
457 nla_put_failure:
458 	return -1;
459 }
460 
461 static struct nft_expr_type nft_flow_offload_type;
462 static const struct nft_expr_ops nft_flow_offload_ops = {
463 	.type		= &nft_flow_offload_type,
464 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_flow_offload)),
465 	.eval		= nft_flow_offload_eval,
466 	.init		= nft_flow_offload_init,
467 	.activate	= nft_flow_offload_activate,
468 	.deactivate	= nft_flow_offload_deactivate,
469 	.destroy	= nft_flow_offload_destroy,
470 	.validate	= nft_flow_offload_validate,
471 	.dump		= nft_flow_offload_dump,
472 	.reduce		= NFT_REDUCE_READONLY,
473 };
474 
475 static struct nft_expr_type nft_flow_offload_type __read_mostly = {
476 	.name		= "flow_offload",
477 	.ops		= &nft_flow_offload_ops,
478 	.policy		= nft_flow_offload_policy,
479 	.maxattr	= NFTA_FLOW_MAX,
480 	.owner		= THIS_MODULE,
481 };
482 
483 static int flow_offload_netdev_event(struct notifier_block *this,
484 				     unsigned long event, void *ptr)
485 {
486 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
487 
488 	if (event != NETDEV_DOWN)
489 		return NOTIFY_DONE;
490 
491 	nf_flow_table_cleanup(dev);
492 
493 	return NOTIFY_DONE;
494 }
495 
496 static struct notifier_block flow_offload_netdev_notifier = {
497 	.notifier_call	= flow_offload_netdev_event,
498 };
499 
500 static int __init nft_flow_offload_module_init(void)
501 {
502 	int err;
503 
504 	err = register_netdevice_notifier(&flow_offload_netdev_notifier);
505 	if (err)
506 		goto err;
507 
508 	err = nft_register_expr(&nft_flow_offload_type);
509 	if (err < 0)
510 		goto register_expr;
511 
512 	return 0;
513 
514 register_expr:
515 	unregister_netdevice_notifier(&flow_offload_netdev_notifier);
516 err:
517 	return err;
518 }
519 
520 static void __exit nft_flow_offload_module_exit(void)
521 {
522 	nft_unregister_expr(&nft_flow_offload_type);
523 	unregister_netdevice_notifier(&flow_offload_netdev_notifier);
524 }
525 
526 module_init(nft_flow_offload_module_init);
527 module_exit(nft_flow_offload_module_exit);
528 
529 MODULE_LICENSE("GPL");
530 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
531 MODULE_ALIAS_NFT_EXPR("flow_offload");
532 MODULE_DESCRIPTION("nftables hardware flow offload module");
533