3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chema Gonzalez <ch...@google.com>
[ Upstream commit 6862234238e84648c305526af2edd98badcad1e0 ]
In the current rxhash calculation function, while the
sorting of the ports/addrs is coherent (you get the
same rxhash for packets sharing the same 4-tuple, in
both directions), ports and addrs are sorted
independently. This implies packets from a connection
between the same addresses but crossed ports hash to
the same rxhash.
For example, traffic between A=S:l and B=L:s is hashed
(in both directions) from {L, S, {s, l}}. The same
rxhash is obtained for packets between C=S:s and D=L:l.
This patch ensures that you either swap both addrs and ports,
or you swap none. Traffic between A and B, and traffic
between C and D, get their rxhash from different sources
({L, S, {l, s}} for A<->B, and {L, S, {s, l}} for C<->D)
The patch is co-written with Eric Dumazet <eduma...@google.com>
Signed-off-by: Chema Gonzalez <ch...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
net/core/dev.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 832ba6d..a4a0c5a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2686,16 +2686,17 @@ ipv6:
nhoff += poff;
if (pskb_may_pull(skb, nhoff + 4)) {
ports.v32 = * (__force u32 *) (skb->data + nhoff);
- if (ports.v16[1] < ports.v16[0])
- swap(ports.v16[0], ports.v16[1]);
skb->l4_rxhash = 1;
}
}
/* get a consistent hash (same value on both flow directions) */
- if (addr2 < addr1)
+ if (addr2 < addr1 ||
+ (addr2 == addr1 &&
+ ports.v16[1] < ports.v16[0])) {
swap(addr1, addr2);
-
+ swap(ports.v16[0], ports.v16[1]);
+ }
hash = jhash_3words(addr1, addr2, ports.v32, hashrnd);
if (!hash)
hash = 1;
--
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