[ovs-dev] [PATCH v2] ofproto-dpif-xlate: Fix check_pkt_larger incomplete translation.

numans at ovn.org numans at ovn.org
Thu Nov 4 23:51:34 UTC 2021


From: Numan Siddique <numans at ovn.org>

xlate_check_pkt_larger() sets ctx->exit to 'true' at the end
causing the translation to stop. This results in incomplete
datapath rules.

For example, for the below OF rules configured on a bridge,

table=0,in_port=1 actions=load:0x1->NXM_NX_REG1[[]],resubmit(,1),load:0x2->NXM_NX_REG1[[]],resubmit(,1),load:0x3->NXM_NX_REG1[[]],resubmit(,1)
table=1,in_port=1,reg1=0x1 actions=check_pkt_larger(200)->NXM_NX_REG0[[0]],resubmit(,4)
table=1,in_port=1,reg1=0x2 actions=output:2
table=1,in_port=1,reg1=0x3 actions=output:4
table=4,in_port=1 actions=output:3

the datapath flow should be

check_pkt_len(size=200,gt(3),le(3)),2,4

But right now it is:

check_pkt_len(size=200,gt(3),le(3))

Actions after the first resubmit(,1) in the first flow in table 0
are never applied.  This patch fixes this issue.

Fixes: 5b34f8fc3b38 ("Add a new OVS action check_pkt_larger")
Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=2018365
Reported-by: Ihar Hrachyshka <ihrachys at redhat.com>
Signed-off-by: Numan Siddique <numans at ovn.org>
---

v1 -> v2
----
 * Fixed the heap buffer overflow error reported by libasan

 ofproto/ofproto-dpif-xlate.c | 12 ++++++++++--
 tests/ofproto-dpif.at        | 17 +++++++++++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
index 9d336bc6a6..8ee6f5a4c6 100644
--- a/ofproto/ofproto-dpif-xlate.c
+++ b/ofproto/ofproto-dpif-xlate.c
@@ -6371,6 +6371,7 @@ xlate_check_pkt_larger(struct xlate_ctx *ctx,
      * then ctx->exit would be true. Reset to false so that we can
      * do flow translation for 'IF_LESS_EQUAL' case. finish_freezing()
      * would have taken care of Undoing the changes done for freeze. */
+    bool old_exit = ctx->exit;
     ctx->exit = false;
 
     offset_attr = nl_msg_start_nested(
@@ -6395,7 +6396,7 @@ xlate_check_pkt_larger(struct xlate_ctx *ctx,
     ctx->was_mpls = old_was_mpls;
     ctx->conntracked = old_conntracked;
     ctx->xin->flow = old_flow;
-    ctx->exit = true;
+    ctx->exit = old_exit;
 }
 
 static void
@@ -6776,6 +6777,7 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
         return;
     }
 
+    bool exit = false;
     OFPACT_FOR_EACH (a, ofpacts, ofpacts_len) {
         struct ofpact_controller *controller;
         const struct ofpact_metadata *metadata;
@@ -6790,7 +6792,7 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
 
         recirc_for_mpls(a, ctx);
 
-        if (ctx->exit) {
+        if (ctx->exit || exit) {
             /* Check if need to store the remaining actions for later
              * execution. */
             if (ctx->freezing) {
@@ -7192,6 +7194,12 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
                                                              ofpacts_len);
             xlate_check_pkt_larger(ctx, ofpact_get_CHECK_PKT_LARGER(a),
                                    remaining_acts, remaining_acts_len);
+            if (ctx->xbridge->support.check_pkt_len) {
+                /* If datapath supports check_pkt_len, then
+                 * xlate_check_pkt_larger() does the translation for the
+                 * ofpacts following 'a'. */
+                exit = true;
+            }
             break;
         }
         }
diff --git a/tests/ofproto-dpif.at b/tests/ofproto-dpif.at
index 31fb163a91..f7c8f98ce5 100644
--- a/tests/ofproto-dpif.at
+++ b/tests/ofproto-dpif.at
@@ -11452,6 +11452,23 @@ Megaflow: recirc_id=0x3,eth,ip,in_port=1,nw_frag=no
 Datapath actions: 4
 ])
 
+ovs-ofctl del-flows br0
+
+AT_DATA([flows.txt], [dnl
+table=0,in_port=1 actions=load:0x1->NXM_NX_REG1[[]],resubmit(,1),load:0x2->NXM_NX_REG1[[]],resubmit(,1),load:0x3->NXM_NX_REG1[[]],resubmit(,1)
+table=1,in_port=1,reg1=0x1 actions=check_pkt_larger(200)->NXM_NX_REG0[[0]],resubmit(,4)
+table=1,in_port=1,reg1=0x2 actions=output:2
+table=1,in_port=1,reg1=0x3 actions=output:4
+table=4,in_port=1 actions=output:3
+])
+
+AT_CHECK([ovs-ofctl --protocols=OpenFlow10 add-flows br0 flows.txt])
+AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=50:54:00:00:00:09,dst=50:54:00:00:00:0a),eth_type(0x0800),ipv4(src=10.10.10.2,dst=10.10.10.1,proto=1,tos=1,ttl=128,frag=no),icmp(type=8,code=0)'], [0], [stdout])
+AT_CHECK([cat stdout | grep Datapath -B1], [0], [dnl
+Megaflow: recirc_id=0,eth,ip,in_port=1,nw_frag=no
+Datapath actions: check_pkt_len(size=200,gt(3),le(3)),2,4
+])
+
 OVS_VSWITCHD_STOP
 AT_CLEANUP
 
-- 
2.31.1



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