Re: [PATCH RFC net-next 4/4] ipv6: route: dissect flow in input path if fib rules need it

[Ido Schimmel <idosch@idosch.org>]

On Sun, Feb 11, 2018 at 02:26:29PM -0800, Roopa Prabhu wrote:
> From: Roopa Prabhu <roopa@cumulusnetworks.com>
> 
> 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 <roopa@cumulusnetworks.com>
> ---
>  include/net/ip6_route.h  |  3 ++-
>  include/net/netns/ipv6.h |  1 +
>  net/ipv6/fib6_rules.c    | 12 +++++++++---
>  net/ipv6/icmp.c          |  2 +-
>  net/ipv6/route.c         | 45 ++++++++++++++++++++++++++++++++++++---------
>  5 files changed, 49 insertions(+), 14 deletions(-)
> 
> diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
> index 27d23a6..218f89c 100644
> --- a/include/net/ip6_route.h
> +++ b/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);
>  
> diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
> index 987cc45..7aca00e 100644
> --- a/include/net/netns/ipv6.h
> +++ b/include/net/netns/ipv6.h
> @@ -72,6 +72,7 @@ struct netns_ipv6 {
>  	unsigned long		 ip6_rt_last_gc;
>  #ifdef CONFIG_IPV6_MULTIPLE_TABLES
>  	bool			 fib6_has_custom_rules;
> +	bool			 fib6_rules_require_fldissect;
>  	struct rt6_info         *ip6_prohibit_entry;
>  	struct rt6_info         *ip6_blk_hole_entry;
>  	struct fib6_table       *fib6_local_tbl;

[...]

> @@ -1847,12 +1858,27 @@ 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;
> +
> +#ifdef CONFIG_IP_MULTIPLE_TABLES

s/CONFIG_IP_MULTIPLE_TABLES/CONFIG_IPV6_MULTIPLE_TABLES/ ?

> +	if (net->ipv6.fib6_rules_require_fldissect) {
> +		unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;
> +
> +		memset(&_flkeys, 0, sizeof(_flkeys));
> +		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;
> +		flkeys = &_flkeys;
> +	}
> +#endif