Re: [PATCH net-next 4/5] ipv4: route: dissect flow in input path if fib rules need it

From: Roopa Prabhu <redacted>

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 (Thanks to Nikolay Aleksandrov for some review here).

Signed-off-by: Roopa Prabhu <redacted>
---
 include/net/ip_fib.h     |  2 +-
 include/net/netns/ipv4.h |  1 +
 net/ipv4/fib_rules.c     |  6 ++++++
 net/ipv4/fib_semantics.c |  2 +-
 net/ipv4/route.c         | 52 +++++++++++++++++++++++++++++++++++-------------
 5 files changed, 47 insertions(+), 16 deletions(-)

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index f805243..5ada772 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h

@@ -371,7 +371,7 @@ int fib_sync_up(struct net_device *dev, unsigned int nh_flags);
 
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 int fib_multipath_hash(const struct fib_info *fi, const struct flowi4 *fl4,
-		       const struct sk_buff *skb);
+		       const struct sk_buff *skb, struct flow_keys *flkeys);
 #endif
 void fib_select_multipath(struct fib_result *res, int hash);
 void fib_select_path(struct net *net, struct fib_result *res,

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 44668c2..87b8fdc 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h

@@ -52,6 +52,7 @@ struct netns_ipv4 {
 #ifdef CONFIG_IP_MULTIPLE_TABLES
 	struct fib_rules_ops	*rules_ops;
 	bool			fib_has_custom_rules;
+	bool			fib_rules_require_fldissect;
 	struct fib_table __rcu	*fib_main;
 	struct fib_table __rcu	*fib_default;
 #endif

diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 9d55c90..83aa786 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c

@@ -253,6 +253,11 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 	}
 #endif
 
+	if (rule->ip_proto ||
+	    fib_rule_port_range_valid(&rule->sport_range) ||
+	    fib_rule_port_range_valid(&rule->dport_range))
+		net->ipv4.fib_rules_require_fldissect = true;
+
 	rule4->src_len = frh->src_len;
 	rule4->srcmask = inet_make_mask(rule4->src_len);
 	rule4->dst_len = frh->dst_len;