ipv6: omit traffic class when calculating flow hash

Some of the code paths calculating flow hash for IPv6 use flowlabel member
of struct flowi6 which, despite its name, encodes both flow label and
traffic class. If traffic class changes within a TCP connection (as e.g.
ssh does), ECMP route can switch between path. It's also inconsistent with
other code paths where ip6_flowlabel() (returning only flow label) is used
to feed the key.

Use only flow label everywhere, including one place where hash key is set
using ip6_flowinfo().

Fixes: 51ebd3181572 ("ipv6: add support of equal cost multipath (ECMP)")
Fixes: f70ea018da06 ("net: Add functions to get skb->hash based on flow structures")
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 798558fd16817f540e4e6923f5385fc193197c1e..16475c269749a72f3c487e102e50cabff797317e 100644 (file)
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -907,6 +907,11 @@ static inline __be32 ip6_make_flowinfo(unsigned int tclass, __be32 flowlabel)
        return htonl(tclass << IPV6_TCLASS_SHIFT) | flowlabel;
 }
 
+static inline __be32 flowi6_get_flowlabel(const struct flowi6 *fl6)
+{
+       return fl6->flowlabel & IPV6_FLOWLABEL_MASK;
+}
+
 /*
  *     Prototypes exported by ipv6
  */

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 4fc1e84d77ec1d8469903463e2226fe667d4ece1..53f96e4f7bf593863b584e050eb7628d4023718a 100644 (file)
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -1334,7 +1334,7 @@ __u32 __get_hash_from_flowi6(const struct flowi6 *fl6, struct flow_keys *keys)
        keys->ports.src = fl6->fl6_sport;
        keys->ports.dst = fl6->fl6_dport;
        keys->keyid.keyid = fl6->fl6_gre_key;
-       keys->tags.flow_label = (__force u32)fl6->flowlabel;
+       keys->tags.flow_label = (__force u32)flowi6_get_flowlabel(fl6);
        keys->basic.ip_proto = fl6->flowi6_proto;
 
        return flow_hash_from_keys(keys);

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 22c4de2317d0694db21193a94394bddeb50dd5c9..ce6696acba73e30552d5c559959b18eba2009f04 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1981,7 +1981,7 @@ out:
        } else {
                keys->addrs.v6addrs.src = key_iph->saddr;
                keys->addrs.v6addrs.dst = key_iph->daddr;
-               keys->tags.flow_label = ip6_flowinfo(key_iph);
+               keys->tags.flow_label = ip6_flowlabel(key_iph);
                keys->basic.ip_proto = key_iph->nexthdr;
        }
 }
@@ -2002,7 +2002,7 @@ u32 rt6_multipath_hash(const struct net *net, const struct flowi6 *fl6,
                } else {
                        hash_keys.addrs.v6addrs.src = fl6->saddr;
                        hash_keys.addrs.v6addrs.dst = fl6->daddr;
-                       hash_keys.tags.flow_label = (__force u32)fl6->flowlabel;
+                       hash_keys.tags.flow_label = (__force u32)flowi6_get_flowlabel(fl6);
                        hash_keys.basic.ip_proto = fl6->flowi6_proto;
                }
                break;