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 	nf_route(nft_net(pkt), &other_dst, &fl, false, nft_pf(pkt));
254 	if (!other_dst)
255 		return -ENOENT;
256 
257 	nft_default_forward_path(route, this_dst, dir);
258 	nft_default_forward_path(route, other_dst, !dir);
259 
260 	if (route->tuple[dir].xmit_type	== FLOW_OFFLOAD_XMIT_NEIGH &&
261 	    route->tuple[!dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH) {
262 		nft_dev_forward_path(route, ct, dir, ft);
263 		nft_dev_forward_path(route, ct, !dir, ft);
264 	}
265 
266 	return 0;
267 }
268 
269 static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
270 {
271 	if (skb_sec_path(skb))
272 		return true;
273 
274 	if (family == NFPROTO_IPV4) {
275 		const struct ip_options *opt;
276 
277 		opt = &(IPCB(skb)->opt);
278 
279 		if (unlikely(opt->optlen))
280 			return true;
281 	}
282 
283 	return false;
284 }
285 
286 static void nft_flow_offload_eval(const struct nft_expr *expr,
287 				  struct nft_regs *regs,
288 				  const struct nft_pktinfo *pkt)
289 {
290 	struct nft_flow_offload *priv = nft_expr_priv(expr);
291 	struct nf_flowtable *flowtable = &priv->flowtable->data;
292 	struct tcphdr _tcph, *tcph = NULL;
293 	struct nf_flow_route route = {};
294 	enum ip_conntrack_info ctinfo;
295 	struct flow_offload *flow;
296 	enum ip_conntrack_dir dir;
297 	struct nf_conn *ct;
298 	int ret;
299 
300 	if (nft_flow_offload_skip(pkt->skb, nft_pf(pkt)))
301 		goto out;
302 
303 	ct = nf_ct_get(pkt->skb, &ctinfo);
304 	if (!ct)
305 		goto out;
306 
307 	switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
308 	case IPPROTO_TCP:
309 		tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt),
310 					  sizeof(_tcph), &_tcph);
311 		if (unlikely(!tcph || tcph->fin || tcph->rst ||
312 			     !nf_conntrack_tcp_established(ct)))
313 			goto out;
314 		break;
315 	case IPPROTO_UDP:
316 		break;
317 #ifdef CONFIG_NF_CT_PROTO_GRE
318 	case IPPROTO_GRE: {
319 		struct nf_conntrack_tuple *tuple;
320 
321 		if (ct->status & IPS_NAT_MASK)
322 			goto out;
323 		tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
324 		/* No support for GRE v1 */
325 		if (tuple->src.u.gre.key || tuple->dst.u.gre.key)
326 			goto out;
327 		break;
328 	}
329 #endif
330 	default:
331 		goto out;
332 	}
333 
334 	if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
335 	    ct->status & (IPS_SEQ_ADJUST | IPS_NAT_CLASH))
336 		goto out;
337 
338 	if (!nf_ct_is_confirmed(ct))
339 		goto out;
340 
341 	if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
342 		goto out;
343 
344 	dir = CTINFO2DIR(ctinfo);
345 	if (nft_flow_route(pkt, ct, &route, dir, priv->flowtable) < 0)
346 		goto err_flow_route;
347 
348 	flow = flow_offload_alloc(ct);
349 	if (!flow)
350 		goto err_flow_alloc;
351 
352 	if (flow_offload_route_init(flow, &route) < 0)
353 		goto err_flow_add;
354 
355 	if (tcph) {
356 		ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
357 		ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
358 	}
359 
360 	ret = flow_offload_add(flowtable, flow);
361 	if (ret < 0)
362 		goto err_flow_add;
363 
364 	dst_release(route.tuple[!dir].dst);
365 	return;
366 
367 err_flow_add:
368 	flow_offload_free(flow);
369 err_flow_alloc:
370 	dst_release(route.tuple[!dir].dst);
371 err_flow_route:
372 	clear_bit(IPS_OFFLOAD_BIT, &ct->status);
373 out:
374 	regs->verdict.code = NFT_BREAK;
375 }
376 
377 static int nft_flow_offload_validate(const struct nft_ctx *ctx,
378 				     const struct nft_expr *expr,
379 				     const struct nft_data **data)
380 {
381 	unsigned int hook_mask = (1 << NF_INET_FORWARD);
382 
383 	return nft_chain_validate_hooks(ctx->chain, hook_mask);
384 }
385 
386 static const struct nla_policy nft_flow_offload_policy[NFTA_FLOW_MAX + 1] = {
387 	[NFTA_FLOW_TABLE_NAME]	= { .type = NLA_STRING,
388 				    .len = NFT_NAME_MAXLEN - 1 },
389 };
390 
391 static int nft_flow_offload_init(const struct nft_ctx *ctx,
392 				 const struct nft_expr *expr,
393 				 const struct nlattr * const tb[])
394 {
395 	struct nft_flow_offload *priv = nft_expr_priv(expr);
396 	u8 genmask = nft_genmask_next(ctx->net);
397 	struct nft_flowtable *flowtable;
398 
399 	if (!tb[NFTA_FLOW_TABLE_NAME])
400 		return -EINVAL;
401 
402 	flowtable = nft_flowtable_lookup(ctx->table, tb[NFTA_FLOW_TABLE_NAME],
403 					 genmask);
404 	if (IS_ERR(flowtable))
405 		return PTR_ERR(flowtable);
406 
407 	priv->flowtable = flowtable;
408 	flowtable->use++;
409 
410 	return nf_ct_netns_get(ctx->net, ctx->family);
411 }
412 
413 static void nft_flow_offload_deactivate(const struct nft_ctx *ctx,
414 					const struct nft_expr *expr,
415 					enum nft_trans_phase phase)
416 {
417 	struct nft_flow_offload *priv = nft_expr_priv(expr);
418 
419 	nf_tables_deactivate_flowtable(ctx, priv->flowtable, phase);
420 }
421 
422 static void nft_flow_offload_activate(const struct nft_ctx *ctx,
423 				      const struct nft_expr *expr)
424 {
425 	struct nft_flow_offload *priv = nft_expr_priv(expr);
426 
427 	priv->flowtable->use++;
428 }
429 
430 static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
431 				     const struct nft_expr *expr)
432 {
433 	nf_ct_netns_put(ctx->net, ctx->family);
434 }
435 
436 static int nft_flow_offload_dump(struct sk_buff *skb,
437 				 const struct nft_expr *expr, bool reset)
438 {
439 	struct nft_flow_offload *priv = nft_expr_priv(expr);
440 
441 	if (nla_put_string(skb, NFTA_FLOW_TABLE_NAME, priv->flowtable->name))
442 		goto nla_put_failure;
443 
444 	return 0;
445 
446 nla_put_failure:
447 	return -1;
448 }
449 
450 static struct nft_expr_type nft_flow_offload_type;
451 static const struct nft_expr_ops nft_flow_offload_ops = {
452 	.type		= &nft_flow_offload_type,
453 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_flow_offload)),
454 	.eval		= nft_flow_offload_eval,
455 	.init		= nft_flow_offload_init,
456 	.activate	= nft_flow_offload_activate,
457 	.deactivate	= nft_flow_offload_deactivate,
458 	.destroy	= nft_flow_offload_destroy,
459 	.validate	= nft_flow_offload_validate,
460 	.dump		= nft_flow_offload_dump,
461 	.reduce		= NFT_REDUCE_READONLY,
462 };
463 
464 static struct nft_expr_type nft_flow_offload_type __read_mostly = {
465 	.name		= "flow_offload",
466 	.ops		= &nft_flow_offload_ops,
467 	.policy		= nft_flow_offload_policy,
468 	.maxattr	= NFTA_FLOW_MAX,
469 	.owner		= THIS_MODULE,
470 };
471 
472 static int flow_offload_netdev_event(struct notifier_block *this,
473 				     unsigned long event, void *ptr)
474 {
475 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
476 
477 	if (event != NETDEV_DOWN)
478 		return NOTIFY_DONE;
479 
480 	nf_flow_table_cleanup(dev);
481 
482 	return NOTIFY_DONE;
483 }
484 
485 static struct notifier_block flow_offload_netdev_notifier = {
486 	.notifier_call	= flow_offload_netdev_event,
487 };
488 
489 static int __init nft_flow_offload_module_init(void)
490 {
491 	int err;
492 
493 	err = register_netdevice_notifier(&flow_offload_netdev_notifier);
494 	if (err)
495 		goto err;
496 
497 	err = nft_register_expr(&nft_flow_offload_type);
498 	if (err < 0)
499 		goto register_expr;
500 
501 	return 0;
502 
503 register_expr:
504 	unregister_netdevice_notifier(&flow_offload_netdev_notifier);
505 err:
506 	return err;
507 }
508 
509 static void __exit nft_flow_offload_module_exit(void)
510 {
511 	nft_unregister_expr(&nft_flow_offload_type);
512 	unregister_netdevice_notifier(&flow_offload_netdev_notifier);
513 }
514 
515 module_init(nft_flow_offload_module_init);
516 module_exit(nft_flow_offload_module_exit);
517 
518 MODULE_LICENSE("GPL");
519 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
520 MODULE_ALIAS_NFT_EXPR("flow_offload");
521 MODULE_DESCRIPTION("nftables hardware flow offload module");
522