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/inet_dscp.h>
13  #include <net/netfilter/nf_tables.h>
14  #include <net/netfilter/nf_tables_core.h>
15  #include <net/netfilter/nf_conntrack_core.h>
16  #include <net/netfilter/nf_conntrack_extend.h>
17  #include <net/netfilter/nf_flow_table.h>
18  
19  struct nft_flow_offload {
20  	struct nft_flowtable	*flowtable;
21  };
22  
nft_xmit_type(struct dst_entry * dst)23  static enum flow_offload_xmit_type nft_xmit_type(struct dst_entry *dst)
24  {
25  	if (dst_xfrm(dst))
26  		return FLOW_OFFLOAD_XMIT_XFRM;
27  
28  	return FLOW_OFFLOAD_XMIT_NEIGH;
29  }
30  
nft_default_forward_path(struct nf_flow_route * route,struct dst_entry * dst_cache,enum ip_conntrack_dir dir)31  static void nft_default_forward_path(struct nf_flow_route *route,
32  				     struct dst_entry *dst_cache,
33  				     enum ip_conntrack_dir dir)
34  {
35  	route->tuple[!dir].in.ifindex	= dst_cache->dev->ifindex;
36  	route->tuple[dir].dst		= dst_cache;
37  	route->tuple[dir].xmit_type	= nft_xmit_type(dst_cache);
38  }
39  
nft_is_valid_ether_device(const struct net_device * dev)40  static bool nft_is_valid_ether_device(const struct net_device *dev)
41  {
42  	if (!dev || (dev->flags & IFF_LOOPBACK) || dev->type != ARPHRD_ETHER ||
43  	    dev->addr_len != ETH_ALEN || !is_valid_ether_addr(dev->dev_addr))
44  		return false;
45  
46  	return true;
47  }
48  
nft_dev_fill_forward_path(const struct nf_flow_route * route,const struct dst_entry * dst_cache,const struct nf_conn * ct,enum ip_conntrack_dir dir,u8 * ha,struct net_device_path_stack * stack)49  static int nft_dev_fill_forward_path(const struct nf_flow_route *route,
50  				     const struct dst_entry *dst_cache,
51  				     const struct nf_conn *ct,
52  				     enum ip_conntrack_dir dir, u8 *ha,
53  				     struct net_device_path_stack *stack)
54  {
55  	const void *daddr = &ct->tuplehash[!dir].tuple.src.u3;
56  	struct net_device *dev = dst_cache->dev;
57  	struct neighbour *n;
58  	u8 nud_state;
59  
60  	if (!nft_is_valid_ether_device(dev))
61  		goto out;
62  
63  	n = dst_neigh_lookup(dst_cache, daddr);
64  	if (!n)
65  		return -1;
66  
67  	read_lock_bh(&n->lock);
68  	nud_state = n->nud_state;
69  	ether_addr_copy(ha, n->ha);
70  	read_unlock_bh(&n->lock);
71  	neigh_release(n);
72  
73  	if (!(nud_state & NUD_VALID))
74  		return -1;
75  
76  out:
77  	return dev_fill_forward_path(dev, ha, stack);
78  }
79  
80  struct nft_forward_info {
81  	const struct net_device *indev;
82  	const struct net_device *outdev;
83  	const struct net_device *hw_outdev;
84  	struct id {
85  		__u16	id;
86  		__be16	proto;
87  	} encap[NF_FLOW_TABLE_ENCAP_MAX];
88  	u8 num_encaps;
89  	u8 ingress_vlans;
90  	u8 h_source[ETH_ALEN];
91  	u8 h_dest[ETH_ALEN];
92  	enum flow_offload_xmit_type xmit_type;
93  };
94  
nft_dev_path_info(const struct net_device_path_stack * stack,struct nft_forward_info * info,unsigned char * ha,struct nf_flowtable * flowtable)95  static void nft_dev_path_info(const struct net_device_path_stack *stack,
96  			      struct nft_forward_info *info,
97  			      unsigned char *ha, struct nf_flowtable *flowtable)
98  {
99  	const struct net_device_path *path;
100  	int i;
101  
102  	memcpy(info->h_dest, ha, ETH_ALEN);
103  
104  	for (i = 0; i < stack->num_paths; i++) {
105  		path = &stack->path[i];
106  		switch (path->type) {
107  		case DEV_PATH_ETHERNET:
108  		case DEV_PATH_DSA:
109  		case DEV_PATH_VLAN:
110  		case DEV_PATH_PPPOE:
111  			info->indev = path->dev;
112  			if (is_zero_ether_addr(info->h_source))
113  				memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
114  
115  			if (path->type == DEV_PATH_ETHERNET)
116  				break;
117  			if (path->type == DEV_PATH_DSA) {
118  				i = stack->num_paths;
119  				break;
120  			}
121  
122  			/* DEV_PATH_VLAN and DEV_PATH_PPPOE */
123  			if (info->num_encaps >= NF_FLOW_TABLE_ENCAP_MAX) {
124  				info->indev = NULL;
125  				break;
126  			}
127  			if (!info->outdev)
128  				info->outdev = path->dev;
129  			info->encap[info->num_encaps].id = path->encap.id;
130  			info->encap[info->num_encaps].proto = path->encap.proto;
131  			info->num_encaps++;
132  			if (path->type == DEV_PATH_PPPOE)
133  				memcpy(info->h_dest, path->encap.h_dest, ETH_ALEN);
134  			break;
135  		case DEV_PATH_BRIDGE:
136  			if (is_zero_ether_addr(info->h_source))
137  				memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
138  
139  			switch (path->bridge.vlan_mode) {
140  			case DEV_PATH_BR_VLAN_UNTAG_HW:
141  				info->ingress_vlans |= BIT(info->num_encaps - 1);
142  				break;
143  			case DEV_PATH_BR_VLAN_TAG:
144  				info->encap[info->num_encaps].id = path->bridge.vlan_id;
145  				info->encap[info->num_encaps].proto = path->bridge.vlan_proto;
146  				info->num_encaps++;
147  				break;
148  			case DEV_PATH_BR_VLAN_UNTAG:
149  				info->num_encaps--;
150  				break;
151  			case DEV_PATH_BR_VLAN_KEEP:
152  				break;
153  			}
154  			info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
155  			break;
156  		default:
157  			info->indev = NULL;
158  			break;
159  		}
160  	}
161  	if (!info->outdev)
162  		info->outdev = info->indev;
163  
164  	info->hw_outdev = info->indev;
165  
166  	if (nf_flowtable_hw_offload(flowtable) &&
167  	    nft_is_valid_ether_device(info->indev))
168  		info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
169  }
170  
nft_flowtable_find_dev(const struct net_device * dev,struct nft_flowtable * ft)171  static bool nft_flowtable_find_dev(const struct net_device *dev,
172  				   struct nft_flowtable *ft)
173  {
174  	struct nft_hook *hook;
175  	bool found = false;
176  
177  	list_for_each_entry_rcu(hook, &ft->hook_list, list) {
178  		if (hook->ops.dev != dev)
179  			continue;
180  
181  		found = true;
182  		break;
183  	}
184  
185  	return found;
186  }
187  
nft_dev_forward_path(struct nf_flow_route * route,const struct nf_conn * ct,enum ip_conntrack_dir dir,struct nft_flowtable * ft)188  static void nft_dev_forward_path(struct nf_flow_route *route,
189  				 const struct nf_conn *ct,
190  				 enum ip_conntrack_dir dir,
191  				 struct nft_flowtable *ft)
192  {
193  	const struct dst_entry *dst = route->tuple[dir].dst;
194  	struct net_device_path_stack stack;
195  	struct nft_forward_info info = {};
196  	unsigned char ha[ETH_ALEN];
197  	int i;
198  
199  	if (nft_dev_fill_forward_path(route, dst, ct, dir, ha, &stack) >= 0)
200  		nft_dev_path_info(&stack, &info, ha, &ft->data);
201  
202  	if (!info.indev || !nft_flowtable_find_dev(info.indev, ft))
203  		return;
204  
205  	route->tuple[!dir].in.ifindex = info.indev->ifindex;
206  	for (i = 0; i < info.num_encaps; i++) {
207  		route->tuple[!dir].in.encap[i].id = info.encap[i].id;
208  		route->tuple[!dir].in.encap[i].proto = info.encap[i].proto;
209  	}
210  	route->tuple[!dir].in.num_encaps = info.num_encaps;
211  	route->tuple[!dir].in.ingress_vlans = info.ingress_vlans;
212  
213  	if (info.xmit_type == FLOW_OFFLOAD_XMIT_DIRECT) {
214  		memcpy(route->tuple[dir].out.h_source, info.h_source, ETH_ALEN);
215  		memcpy(route->tuple[dir].out.h_dest, info.h_dest, ETH_ALEN);
216  		route->tuple[dir].out.ifindex = info.outdev->ifindex;
217  		route->tuple[dir].out.hw_ifindex = info.hw_outdev->ifindex;
218  		route->tuple[dir].xmit_type = info.xmit_type;
219  	}
220  }
221  
nft_flow_route(const struct nft_pktinfo * pkt,const struct nf_conn * ct,struct nf_flow_route * route,enum ip_conntrack_dir dir,struct nft_flowtable * ft)222  static int nft_flow_route(const struct nft_pktinfo *pkt,
223  			  const struct nf_conn *ct,
224  			  struct nf_flow_route *route,
225  			  enum ip_conntrack_dir dir,
226  			  struct nft_flowtable *ft)
227  {
228  	struct dst_entry *this_dst = skb_dst(pkt->skb);
229  	struct dst_entry *other_dst = NULL;
230  	struct flowi fl;
231  
232  	memset(&fl, 0, sizeof(fl));
233  	switch (nft_pf(pkt)) {
234  	case NFPROTO_IPV4:
235  		fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
236  		fl.u.ip4.saddr = ct->tuplehash[!dir].tuple.src.u3.ip;
237  		fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
238  		fl.u.ip4.flowi4_iif = this_dst->dev->ifindex;
239  		fl.u.ip4.flowi4_tos = ip_hdr(pkt->skb)->tos & INET_DSCP_MASK;
240  		fl.u.ip4.flowi4_mark = pkt->skb->mark;
241  		fl.u.ip4.flowi4_flags = FLOWI_FLAG_ANYSRC;
242  		break;
243  	case NFPROTO_IPV6:
244  		fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
245  		fl.u.ip6.saddr = ct->tuplehash[!dir].tuple.src.u3.in6;
246  		fl.u.ip6.flowi6_oif = nft_in(pkt)->ifindex;
247  		fl.u.ip6.flowi6_iif = this_dst->dev->ifindex;
248  		fl.u.ip6.flowlabel = ip6_flowinfo(ipv6_hdr(pkt->skb));
249  		fl.u.ip6.flowi6_mark = pkt->skb->mark;
250  		fl.u.ip6.flowi6_flags = FLOWI_FLAG_ANYSRC;
251  		break;
252  	}
253  
254  	if (!dst_hold_safe(this_dst))
255  		return -ENOENT;
256  
257  	nf_route(nft_net(pkt), &other_dst, &fl, false, nft_pf(pkt));
258  	if (!other_dst) {
259  		dst_release(this_dst);
260  		return -ENOENT;
261  	}
262  
263  	nft_default_forward_path(route, this_dst, dir);
264  	nft_default_forward_path(route, other_dst, !dir);
265  
266  	if (route->tuple[dir].xmit_type	== FLOW_OFFLOAD_XMIT_NEIGH &&
267  	    route->tuple[!dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH) {
268  		nft_dev_forward_path(route, ct, dir, ft);
269  		nft_dev_forward_path(route, ct, !dir, ft);
270  	}
271  
272  	return 0;
273  }
274  
nft_flow_offload_skip(struct sk_buff * skb,int family)275  static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
276  {
277  	if (skb_sec_path(skb))
278  		return true;
279  
280  	if (family == NFPROTO_IPV4) {
281  		const struct ip_options *opt;
282  
283  		opt = &(IPCB(skb)->opt);
284  
285  		if (unlikely(opt->optlen))
286  			return true;
287  	}
288  
289  	return false;
290  }
291  
nft_flow_offload_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)292  static void nft_flow_offload_eval(const struct nft_expr *expr,
293  				  struct nft_regs *regs,
294  				  const struct nft_pktinfo *pkt)
295  {
296  	struct nft_flow_offload *priv = nft_expr_priv(expr);
297  	struct nf_flowtable *flowtable = &priv->flowtable->data;
298  	struct tcphdr _tcph, *tcph = NULL;
299  	struct nf_flow_route route = {};
300  	enum ip_conntrack_info ctinfo;
301  	struct flow_offload *flow;
302  	enum ip_conntrack_dir dir;
303  	struct nf_conn *ct;
304  	int ret;
305  
306  	if (nft_flow_offload_skip(pkt->skb, nft_pf(pkt)))
307  		goto out;
308  
309  	ct = nf_ct_get(pkt->skb, &ctinfo);
310  	if (!ct)
311  		goto out;
312  
313  	switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
314  	case IPPROTO_TCP:
315  		tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt),
316  					  sizeof(_tcph), &_tcph);
317  		if (unlikely(!tcph || tcph->fin || tcph->rst ||
318  			     !nf_conntrack_tcp_established(ct)))
319  			goto out;
320  		break;
321  	case IPPROTO_UDP:
322  		break;
323  #ifdef CONFIG_NF_CT_PROTO_GRE
324  	case IPPROTO_GRE: {
325  		struct nf_conntrack_tuple *tuple;
326  
327  		if (ct->status & IPS_NAT_MASK)
328  			goto out;
329  		tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
330  		/* No support for GRE v1 */
331  		if (tuple->src.u.gre.key || tuple->dst.u.gre.key)
332  			goto out;
333  		break;
334  	}
335  #endif
336  	default:
337  		goto out;
338  	}
339  
340  	if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
341  	    ct->status & (IPS_SEQ_ADJUST | IPS_NAT_CLASH))
342  		goto out;
343  
344  	if (!nf_ct_is_confirmed(ct))
345  		goto out;
346  
347  	if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
348  		goto out;
349  
350  	dir = CTINFO2DIR(ctinfo);
351  	if (nft_flow_route(pkt, ct, &route, dir, priv->flowtable) < 0)
352  		goto err_flow_route;
353  
354  	flow = flow_offload_alloc(ct);
355  	if (!flow)
356  		goto err_flow_alloc;
357  
358  	flow_offload_route_init(flow, &route);
359  
360  	if (tcph) {
361  		ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
362  		ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
363  	}
364  
365  	__set_bit(NF_FLOW_HW_BIDIRECTIONAL, &flow->flags);
366  	ret = flow_offload_add(flowtable, flow);
367  	if (ret < 0)
368  		goto err_flow_add;
369  
370  	return;
371  
372  err_flow_add:
373  	flow_offload_free(flow);
374  err_flow_alloc:
375  	dst_release(route.tuple[dir].dst);
376  	dst_release(route.tuple[!dir].dst);
377  err_flow_route:
378  	clear_bit(IPS_OFFLOAD_BIT, &ct->status);
379  out:
380  	regs->verdict.code = NFT_BREAK;
381  }
382  
nft_flow_offload_validate(const struct nft_ctx * ctx,const struct nft_expr * expr)383  static int nft_flow_offload_validate(const struct nft_ctx *ctx,
384  				     const struct nft_expr *expr)
385  {
386  	unsigned int hook_mask = (1 << NF_INET_FORWARD);
387  
388  	if (ctx->family != NFPROTO_IPV4 &&
389  	    ctx->family != NFPROTO_IPV6 &&
390  	    ctx->family != NFPROTO_INET)
391  		return -EOPNOTSUPP;
392  
393  	return nft_chain_validate_hooks(ctx->chain, hook_mask);
394  }
395  
396  static const struct nla_policy nft_flow_offload_policy[NFTA_FLOW_MAX + 1] = {
397  	[NFTA_FLOW_TABLE_NAME]	= { .type = NLA_STRING,
398  				    .len = NFT_NAME_MAXLEN - 1 },
399  };
400  
nft_flow_offload_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])401  static int nft_flow_offload_init(const struct nft_ctx *ctx,
402  				 const struct nft_expr *expr,
403  				 const struct nlattr * const tb[])
404  {
405  	struct nft_flow_offload *priv = nft_expr_priv(expr);
406  	u8 genmask = nft_genmask_next(ctx->net);
407  	struct nft_flowtable *flowtable;
408  
409  	if (!tb[NFTA_FLOW_TABLE_NAME])
410  		return -EINVAL;
411  
412  	flowtable = nft_flowtable_lookup(ctx->table, tb[NFTA_FLOW_TABLE_NAME],
413  					 genmask);
414  	if (IS_ERR(flowtable))
415  		return PTR_ERR(flowtable);
416  
417  	if (!nft_use_inc(&flowtable->use))
418  		return -EMFILE;
419  
420  	priv->flowtable = flowtable;
421  
422  	return nf_ct_netns_get(ctx->net, ctx->family);
423  }
424  
nft_flow_offload_deactivate(const struct nft_ctx * ctx,const struct nft_expr * expr,enum nft_trans_phase phase)425  static void nft_flow_offload_deactivate(const struct nft_ctx *ctx,
426  					const struct nft_expr *expr,
427  					enum nft_trans_phase phase)
428  {
429  	struct nft_flow_offload *priv = nft_expr_priv(expr);
430  
431  	nf_tables_deactivate_flowtable(ctx, priv->flowtable, phase);
432  }
433  
nft_flow_offload_activate(const struct nft_ctx * ctx,const struct nft_expr * expr)434  static void nft_flow_offload_activate(const struct nft_ctx *ctx,
435  				      const struct nft_expr *expr)
436  {
437  	struct nft_flow_offload *priv = nft_expr_priv(expr);
438  
439  	nft_use_inc_restore(&priv->flowtable->use);
440  }
441  
nft_flow_offload_destroy(const struct nft_ctx * ctx,const struct nft_expr * expr)442  static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
443  				     const struct nft_expr *expr)
444  {
445  	nf_ct_netns_put(ctx->net, ctx->family);
446  }
447  
nft_flow_offload_dump(struct sk_buff * skb,const struct nft_expr * expr,bool reset)448  static int nft_flow_offload_dump(struct sk_buff *skb,
449  				 const struct nft_expr *expr, bool reset)
450  {
451  	struct nft_flow_offload *priv = nft_expr_priv(expr);
452  
453  	if (nla_put_string(skb, NFTA_FLOW_TABLE_NAME, priv->flowtable->name))
454  		goto nla_put_failure;
455  
456  	return 0;
457  
458  nla_put_failure:
459  	return -1;
460  }
461  
462  static struct nft_expr_type nft_flow_offload_type;
463  static const struct nft_expr_ops nft_flow_offload_ops = {
464  	.type		= &nft_flow_offload_type,
465  	.size		= NFT_EXPR_SIZE(sizeof(struct nft_flow_offload)),
466  	.eval		= nft_flow_offload_eval,
467  	.init		= nft_flow_offload_init,
468  	.activate	= nft_flow_offload_activate,
469  	.deactivate	= nft_flow_offload_deactivate,
470  	.destroy	= nft_flow_offload_destroy,
471  	.validate	= nft_flow_offload_validate,
472  	.dump		= nft_flow_offload_dump,
473  	.reduce		= NFT_REDUCE_READONLY,
474  };
475  
476  static struct nft_expr_type nft_flow_offload_type __read_mostly = {
477  	.name		= "flow_offload",
478  	.ops		= &nft_flow_offload_ops,
479  	.policy		= nft_flow_offload_policy,
480  	.maxattr	= NFTA_FLOW_MAX,
481  	.owner		= THIS_MODULE,
482  };
483  
flow_offload_netdev_event(struct notifier_block * this,unsigned long event,void * ptr)484  static int flow_offload_netdev_event(struct notifier_block *this,
485  				     unsigned long event, void *ptr)
486  {
487  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
488  
489  	if (event != NETDEV_DOWN)
490  		return NOTIFY_DONE;
491  
492  	nf_flow_table_cleanup(dev);
493  
494  	return NOTIFY_DONE;
495  }
496  
497  static struct notifier_block flow_offload_netdev_notifier = {
498  	.notifier_call	= flow_offload_netdev_event,
499  };
500  
nft_flow_offload_module_init(void)501  static int __init nft_flow_offload_module_init(void)
502  {
503  	int err;
504  
505  	err = register_netdevice_notifier(&flow_offload_netdev_notifier);
506  	if (err)
507  		goto err;
508  
509  	err = nft_register_expr(&nft_flow_offload_type);
510  	if (err < 0)
511  		goto register_expr;
512  
513  	return 0;
514  
515  register_expr:
516  	unregister_netdevice_notifier(&flow_offload_netdev_notifier);
517  err:
518  	return err;
519  }
520  
nft_flow_offload_module_exit(void)521  static void __exit nft_flow_offload_module_exit(void)
522  {
523  	nft_unregister_expr(&nft_flow_offload_type);
524  	unregister_netdevice_notifier(&flow_offload_netdev_notifier);
525  }
526  
527  module_init(nft_flow_offload_module_init);
528  module_exit(nft_flow_offload_module_exit);
529  
530  MODULE_LICENSE("GPL");
531  MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
532  MODULE_ALIAS_NFT_EXPR("flow_offload");
533  MODULE_DESCRIPTION("nftables hardware flow offload module");
534