[NET_SCHED]: Add flow classifier

Add new "flow" classifier, which is meant to extend the SFQ hashing
capabilities without hard-coding new hash functions and also allows
deterministic mappings of keys to classes, replacing some out of tree
iptables patches like IPCLASSIFY (maps IPs to classes), IPMARK (maps
IPs to marks, with fw filters to classes), ...

Some examples:

- Classic SFQ hash:

  tc filter add ... flow hash \
  	keys src,dst,proto,proto-src,proto-dst divisor 1024

- Classic SFQ hash, but using information from conntrack to work properly in
  combination with NAT:

  tc filter add ... flow hash \
  	keys nfct-src,nfct-dst,proto,nfct-proto-src,nfct-proto-dst divisor 1024

- Map destination IPs of 192.168.0.0/24 to classids 1-257:

  tc filter add ... flow map \
  	key dst addend -192.168.0.0 divisor 256

- alternatively:

  tc filter add ... flow map \
  	key dst and 0xff

- similar, but reverse ordered:

  tc filter add ... flow map \
  	key dst and 0xff xor 0xff

Perturbation is currently not supported because we can't reliable kill the
timer on destruction.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 0 deletions

diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index 7d4085a4af66..82adfe6447d7 100644
--- a/net/sched/Kconfig
+++ b/net/sched/Kconfig
@@ -307,6 +307,17 @@ config NET_CLS_RSVP6
           To compile this code as a module, choose M here: the
           module will be called cls_rsvp6.
 
+config NET_CLS_FLOW
+        tristate "Flow classifier"
+        select NET_CLS
+        ---help---
+          If you say Y here, you will be able to classify packets based on
+          a configurable combination of packet keys. This is mostly useful
+          in combination with SFQ.
+
+          To compile this code as a module, choose M here: the
+          module will be called cls_flow.
+
 config NET_EMATCH
         bool "Extended Matches"
         select NET_CLS