netdev-offload-tc: Conntrack ALGs are not supported with tc.

tc does not support conntrack ALGs. Even worse, with tc enabled, they should not be used/configured at all. This is because even though TC will ignore the rules with ALG configured, i.e., they will flow through the kernel module, return traffic might flow through a tc conntrack rule, and it will not invoke the ALG helper. Fixes: 576126a ("netdev-offload-tc: Add conntrack support") Signed-off-by: Eelco Chaudron <[email protected]> Acked-by: Roi Dayan <[email protected]> Reviewed-by: Simon Horman <[email protected]> Tested-by: Simon Horman <[email protected]> Signed-off-by: Ilya Maximets <[email protected]>
nevalosa · Feb 8, 2023 · b292cce · b292cce
1 parent 7a176f9
commit b292cce
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Showing 4 changed files with 21 additions and 15 deletions.
diff --git a/Documentation/howto/tc-offload.rst b/Documentation/howto/tc-offload.rst
@@ -112,3 +112,14 @@ First flow packet not processed by meter
 Packets that are received by ovs-vswitchd through an upcall before the actual
 meter flow is installed, are not passing TC police action and therefore are
 not considered for policing.
+
+Conntrack Application Layer Gateways (ALG)
+++++++++++++++++++++++++++++++++++++++++++
+
+TC does not support conntrack helpers, i.e., ALGs. TC will not offload flows if
+the ALG keyword is present within the ct() action. However, this will not allow
+ALGs to work within the datapath, as the return traffic without the ALG keyword
+might run through a TC rule, which internally will not call the conntrack
+helper required.
+
+So if ALG support is required, tc offload must be disabled.
diff --git a/lib/netdev-offload-tc.c b/lib/netdev-offload-tc.c
@@ -1426,6 +1426,10 @@ parse_put_flow_ct_action(struct tc_flower *flower,
                         get_32aligned_u128(&ct_label->mask);
                 }
                 break;
+                /* The following option we do not support in tc-ct, and should
+                 * not be ignored for proper operation. */
+                case OVS_CT_ATTR_HELPER:
+                    return EOPNOTSUPP;
             }
         }
 

diff --git a/tests/system-offloads-testsuite-macros.at b/tests/system-offloads-testsuite-macros.at
@@ -34,3 +34,9 @@ m4_define([CHECK_NO_TC_OFFLOAD],
 [
      AT_SKIP_IF([:])
 ])
+
+# Conntrack ALGs are not supported for tc.
+m4_define([CHECK_CONNTRACK_ALG],
+[
+     AT_SKIP_IF([:])
+])
diff --git a/tests/system-traffic.at b/tests/system-traffic.at
@@ -4890,7 +4890,6 @@ OVS_TRAFFIC_VSWITCHD_STOP
 AT_CLEANUP
 
 AT_SETUP([conntrack - FTP])
-CHECK_NO_TC_OFFLOAD()
 AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_ALG()
@@ -5000,7 +4999,6 @@ AT_SETUP([conntrack - FTP over IPv6])
 AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -5056,7 +5054,6 @@ AT_SETUP([conntrack - IPv6 FTP Passive])
 AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -5116,7 +5113,6 @@ AT_SETUP([conntrack - FTP with multiple expectations])
 AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -5183,7 +5179,6 @@ AT_SETUP([conntrack - TFTP])
 AT_SKIP_IF([test $HAVE_TFTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -5819,7 +5814,6 @@ m4_define([CHECK_FTP_NAT],
     CHECK_CONNTRACK()
     CHECK_CONNTRACK_NAT()
     CHECK_CONNTRACK_ALG()
-    CHECK_NO_TC_OFFLOAD()
 
     OVS_TRAFFIC_VSWITCHD_START()
 
@@ -6127,7 +6121,6 @@ AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_NAT()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 
 OVS_TRAFFIC_VSWITCHD_START()
 
@@ -6188,7 +6181,6 @@ AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_NAT()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 
 OVS_TRAFFIC_VSWITCHD_START()
 
@@ -6249,7 +6241,6 @@ AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_NAT()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 
 OVS_TRAFFIC_VSWITCHD_START()
 
@@ -6310,7 +6301,6 @@ AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_NAT()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 
 OVS_TRAFFIC_VSWITCHD_START()
 
@@ -6371,7 +6361,6 @@ AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_NAT()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 
 OVS_TRAFFIC_VSWITCHD_START()
 
@@ -6574,7 +6563,6 @@ AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_NAT()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 
 OVS_TRAFFIC_VSWITCHD_START()
 
@@ -6635,7 +6623,6 @@ AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_NAT()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 
 OVS_TRAFFIC_VSWITCHD_START()
 
@@ -6697,7 +6684,6 @@ AT_SKIP_IF([test $HAVE_FTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_NAT()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -6758,7 +6744,6 @@ AT_SKIP_IF([test $HAVE_TFTP = no])
 CHECK_CONNTRACK()
 CHECK_CONNTRACK_NAT()
 CHECK_CONNTRACK_ALG()
-CHECK_NO_TC_OFFLOAD()
 
 OVS_TRAFFIC_VSWITCHD_START()