ipv6: route: dissect flow in input path if fib rules need it

Dissect flow in fwd path if fib rules require it. Controlled by
a flag to avoid penatly for the common case. Flag is set when fib
rules with sport, dport and proto match that require flow dissect
are installed. Also passes the dissected hash keys to the multipath
hash function when applicable to avoid dissecting the flow again.
icmp packets will continue to use inner header for hash
calculations.

Signed-off-by: Roopa Prabhu <[email protected]>
Acked-by: Paolo Abeni <[email protected]>
Acked-by: Nikolay Aleksandrov <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: roopa-prabhu

include/net/ip6_fib.h

@@ -415,6 +415,24 @@ void fib6_rules_cleanup(void);
 bool fib6_rule_default(const struct fib_rule *rule);
 int fib6_rules_dump(struct net *net, struct notifier_block *nb);
 unsigned int fib6_rules_seq_read(struct net *net);
+
+static inline bool fib6_rules_early_flow_dissect(struct net *net,
+						 struct sk_buff *skb,
+						 struct flowi6 *fl6,
+						 struct flow_keys *flkeys)
+{
+	unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;
+
+	if (!net->ipv6.fib6_rules_require_fldissect)
+		return false;
+
+	skb_flow_dissect_flow_keys(skb, flkeys, flag);
+	fl6->fl6_sport = flkeys->ports.src;
+	fl6->fl6_dport = flkeys->ports.dst;
+	fl6->flowi6_proto = flkeys->basic.ip_proto;
+
+	return true;
+}
 #else
 static inline int               fib6_rules_init(void)
 {
@@ -436,5 +454,12 @@ static inline unsigned int fib6_rules_seq_read(struct net *net)
 {
 	return 0;
 }
+static inline bool fib6_rules_early_flow_dissect(struct net *net,
+						 struct sk_buff *skb,
+						 struct flowi6 *fl6,
+						 struct flow_keys *flkeys)
+{
+	return false;
+}
 #endif
 #endif

include/net/ip6_route.h

@@ -127,7 +127,8 @@ static inline int ip6_route_get_saddr(struct net *net, struct rt6_info *rt,
 
 struct rt6_info *rt6_lookup(struct net *net, const struct in6_addr *daddr,
 			    const struct in6_addr *saddr, int oif, int flags);
-u32 rt6_multipath_hash(const struct flowi6 *fl6, const struct sk_buff *skb);
+u32 rt6_multipath_hash(const struct flowi6 *fl6, const struct sk_buff *skb,
+		       struct flow_keys *hkeys);
 
 struct dst_entry *icmp6_dst_alloc(struct net_device *dev, struct flowi6 *fl6);
 
@@ -266,4 +267,5 @@ static inline bool rt6_duplicate_nexthop(struct rt6_info *a, struct rt6_info *b)
 	       ipv6_addr_equal(&a->rt6i_gateway, &b->rt6i_gateway) &&
 	       !lwtunnel_cmp_encap(a->dst.lwtstate, b->dst.lwtstate);
 }
+
 #endif

include/net/netns/ipv6.h

@@ -71,7 +71,8 @@ struct netns_ipv6 {
 	unsigned int		 ip6_rt_gc_expire;
 	unsigned long		 ip6_rt_last_gc;
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
-	bool			 fib6_has_custom_rules;
+	unsigned int		fib6_rules_require_fldissect;
+	bool			fib6_has_custom_rules;
 	struct rt6_info         *ip6_prohibit_entry;
 	struct rt6_info         *ip6_blk_hole_entry;
 	struct fib6_table       *fib6_local_tbl;

net/ipv6/fib6_rules.c

@@ -269,12 +269,26 @@ static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 	rule6->dst.plen = frh->dst_len;
 	rule6->tclass = frh->tos;
 
+	if (fib_rule_requires_fldissect(rule))
+		net->ipv6.fib6_rules_require_fldissect++;
+
 	net->ipv6.fib6_has_custom_rules = true;
 	err = 0;
 errout:
 	return err;
 }
 
+static int fib6_rule_delete(struct fib_rule *rule)
+{
+	struct net *net = rule->fr_net;
+
+	if (net->ipv6.fib6_rules_require_fldissect &&
+	    fib_rule_requires_fldissect(rule))
+		net->ipv6.fib6_rules_require_fldissect--;
+
+	return 0;
+}
+
 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 			     struct nlattr **tb)
 {
@@ -334,6 +348,7 @@ static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
 	.match			= fib6_rule_match,
 	.suppress		= fib6_rule_suppress,
 	.configure		= fib6_rule_configure,
+	.delete			= fib6_rule_delete,
 	.compare		= fib6_rule_compare,
 	.fill			= fib6_rule_fill,
 	.nlmsg_payload		= fib6_rule_nlmsg_payload,
@@ -361,6 +376,7 @@ static int __net_init fib6_rules_net_init(struct net *net)
 		goto out_fib6_rules_ops;
 
 	net->ipv6.fib6_rules_ops = ops;
+	net->ipv6.fib6_rules_require_fldissect = 0;
 out:
 	return err;
 

net/ipv6/icmp.c

@@ -522,7 +522,7 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
 	fl6.fl6_icmp_type = type;
 	fl6.fl6_icmp_code = code;
 	fl6.flowi6_uid = sock_net_uid(net, NULL);
-	fl6.mp_hash = rt6_multipath_hash(&fl6, skb);
+	fl6.mp_hash = rt6_multipath_hash(&fl6, skb, NULL);
 	security_skb_classify_flow(skb, flowi6_to_flowi(&fl6));
 
 	sk = icmpv6_xmit_lock(net);

net/ipv6/route.c

@@ -460,7 +460,7 @@ static struct rt6_info *rt6_multipath_select(struct rt6_info *match,
 	 * case it will always be non-zero. Otherwise now is the time to do it.
 	 */
 	if (!fl6->mp_hash)
-		fl6->mp_hash = rt6_multipath_hash(fl6, NULL);
+		fl6->mp_hash = rt6_multipath_hash(fl6, NULL, NULL);
 
 	if (fl6->mp_hash <= atomic_read(&match->rt6i_nh_upper_bound))
 		return match;
@@ -1786,10 +1786,12 @@ struct dst_entry *ip6_route_input_lookup(struct net *net,
 EXPORT_SYMBOL_GPL(ip6_route_input_lookup);
 
 static void ip6_multipath_l3_keys(const struct sk_buff *skb,
-				  struct flow_keys *keys)
+				  struct flow_keys *keys,
+				  struct flow_keys *flkeys)
 {
 	const struct ipv6hdr *outer_iph = ipv6_hdr(skb);
 	const struct ipv6hdr *key_iph = outer_iph;
+	struct flow_keys *_flkeys = flkeys;
 	const struct ipv6hdr *inner_iph;
 	const struct icmp6hdr *icmph;
 	struct ipv6hdr _inner_iph;
@@ -1811,22 +1813,31 @@ static void ip6_multipath_l3_keys(const struct sk_buff *skb,
 		goto out;
 
 	key_iph = inner_iph;
+	_flkeys = NULL;
 out:
 	memset(keys, 0, sizeof(*keys));
 	keys->control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
-	keys->addrs.v6addrs.src = key_iph->saddr;
-	keys->addrs.v6addrs.dst = key_iph->daddr;
-	keys->tags.flow_label = ip6_flowinfo(key_iph);
-	keys->basic.ip_proto = key_iph->nexthdr;
+	if (_flkeys) {
+		keys->addrs.v6addrs.src = _flkeys->addrs.v6addrs.src;
+		keys->addrs.v6addrs.dst = _flkeys->addrs.v6addrs.dst;
+		keys->tags.flow_label = _flkeys->tags.flow_label;
+		keys->basic.ip_proto = _flkeys->basic.ip_proto;
+	} else {
+		keys->addrs.v6addrs.src = key_iph->saddr;
+		keys->addrs.v6addrs.dst = key_iph->daddr;
+		keys->tags.flow_label = ip6_flowinfo(key_iph);
+		keys->basic.ip_proto = key_iph->nexthdr;
+	}
 }
 
 /* if skb is set it will be used and fl6 can be NULL */
-u32 rt6_multipath_hash(const struct flowi6 *fl6, const struct sk_buff *skb)
+u32 rt6_multipath_hash(const struct flowi6 *fl6, const struct sk_buff *skb,
+		       struct flow_keys *flkeys)
 {
 	struct flow_keys hash_keys;
 
 	if (skb) {
-		ip6_multipath_l3_keys(skb, &hash_keys);
+		ip6_multipath_l3_keys(skb, &hash_keys, flkeys);
 		return flow_hash_from_keys(&hash_keys) >> 1;
 	}
 
@@ -1847,12 +1858,17 @@ void ip6_route_input(struct sk_buff *skb)
 		.flowi6_mark = skb->mark,
 		.flowi6_proto = iph->nexthdr,
 	};
+	struct flow_keys *flkeys = NULL, _flkeys;
 
 	tun_info = skb_tunnel_info(skb);
 	if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
 		fl6.flowi6_tun_key.tun_id = tun_info->key.tun_id;
+
+	if (fib6_rules_early_flow_dissect(net, skb, &fl6, &_flkeys))
+		flkeys = &_flkeys;
+
 	if (unlikely(fl6.flowi6_proto == IPPROTO_ICMPV6))
-		fl6.mp_hash = rt6_multipath_hash(&fl6, skb);
+		fl6.mp_hash = rt6_multipath_hash(&fl6, skb, flkeys);
 	skb_dst_drop(skb);
 	skb_dst_set(skb, ip6_route_input_lookup(net, skb->dev, &fl6, flags));
 }