learn: Fix bugs when learn actions use subfields wider than 64 bits.

Bug #10576.
Reported-by: James Schmidt <jschmidt@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

include/openflow/nicira-ext.h

@@ -787,6 +787,9 @@ enum nx_mp_algorithm {
  *     field[ofs:ofs+n_bits-1].  Actions are executed in the same order as the
  *     flow_mod_specs.
  *
+ *     A single NXAST_REG_LOAD action writes no more than 64 bits, so n_bits
+ *     greater than 64 yields multiple NXAST_REG_LOAD actions.
+ *
  * The flow_mod_spec destination spec for 'dst' of 2 (when 'src' is 0) is
  * empty.  It has the following meaning:
  *

lib/learn.c

@@ -177,7 +177,14 @@ learn_check(const struct nx_action_learn *learn, const struct flow *flow)
 
             if (dst_type == NX_LEARN_DST_MATCH
                 && src_type == NX_LEARN_SRC_IMMEDIATE) {
-                mf_set_subfield(&dst, value, &rule);
+                if (n_bits <= 64) {
+                    mf_set_subfield(&dst, value, &rule);
+                } else {
+                    /* We're only setting subfields to allow us to check
+                     * prerequisites.  No prerequisite depends on the value of
+                     * a field that is wider than 64 bits.  So just skip
+                     * setting it entirely. */
+                }
             }
         }
     }
@@ -223,10 +230,10 @@ learn_execute(const struct nx_action_learn *learn, const struct flow *flow,
         int n_bits = header & NX_LEARN_N_BITS_MASK;
         int src_type = header & NX_LEARN_SRC_MASK;
         int dst_type = header & NX_LEARN_DST_MASK;
-        uint64_t value;
+        union mf_subvalue value;
 
-        struct nx_action_reg_load *load;
         struct mf_subfield dst;
+        int chunk, ofs;
 
         if (!header) {
             break;
@@ -236,27 +243,43 @@ learn_execute(const struct nx_action_learn *learn, const struct flow *flow,
             struct mf_subfield src;
 
             get_subfield(n_bits, &p, &src);
-            value = mf_get_subfield(&src, flow);
+            mf_read_subfield(&src, flow, &value);
         } else {
-            value = get_bits(n_bits, &p);
+            int p_bytes = 2 * DIV_ROUND_UP(n_bits, 16);
+
+            memset(&value, 0, sizeof value);
+            bitwise_copy(p, p_bytes, 0,
+                         &value, sizeof value, 0,
+                         n_bits);
+            p = (const uint8_t *) p + p_bytes;
         }
 
         switch (dst_type) {
         case NX_LEARN_DST_MATCH:
             get_subfield(n_bits, &p, &dst);
-            mf_set_subfield(&dst, value, &fm->cr);
+            mf_write_subfield(&dst, &value, &fm->cr);
             break;
 
         case NX_LEARN_DST_LOAD:
             get_subfield(n_bits, &p, &dst);
-            load = ofputil_put_NXAST_REG_LOAD(&actions);
+            for (ofs = 0; ofs < n_bits; ofs += chunk) {
-            load->ofs_nbits = nxm_encode_ofs_nbits(dst.ofs, dst.n_bits);
+                struct nx_action_reg_load *load;
-            load->dst = htonl(dst.field->nxm_header);
+
-            load->value = htonll(value);
+                chunk = MIN(n_bits - ofs, 64);
+
+                load = ofputil_put_NXAST_REG_LOAD(&actions);
+                load->ofs_nbits = nxm_encode_ofs_nbits(dst.ofs + ofs, chunk);
+                load->dst = htonl(dst.field->nxm_header);
+                bitwise_copy(&value, sizeof value, ofs,
+                             &load->value, sizeof load->value, 0,
+                             chunk);
+            }
             break;
 
         case NX_LEARN_DST_OUTPUT:
-            ofputil_put_OFPAT10_OUTPUT(&actions)->port = htons(value);
+            if (n_bits <= 16 || is_all_zeros(value.u8, sizeof value - 2)) {
+                ofputil_put_OFPAT10_OUTPUT(&actions)->port = value.be16[7];
+            }
             break;
         }
     }

tests/learn.at

@@ -112,6 +112,48 @@ NXST_FLOW reply:
 OVS_VSWITCHD_STOP
 AT_CLEANUP
 
+AT_SETUP([learning action - TCPv4 port learning])
+OVS_VSWITCHD_START(
+  [add-port br0 eth0 -- set Interface eth0 type=dummy -- \
+   add-port br0 eth1 -- set Interface eth1 type=dummy -- \
+   add-port br0 eth2 -- set Interface eth2 type=dummy])
+# Set up flow table for TCPv4 port learning.
+AT_CHECK([[ovs-ofctl add-flow br0 'table=0 tcp actions=learn(table=1, hard_timeout=60, eth_type=0x800, nw_proto=6, NXM_OF_IP_SRC[]=NXM_OF_IP_DST[], NXM_OF_IP_DST[]=NXM_OF_IP_SRC[], NXM_OF_TCP_SRC[]=NXM_OF_TCP_DST[], NXM_OF_TCP_DST[]=NXM_OF_TCP_SRC[]), flood']])
+
+# Trace a TCPv4 packet arriving on port 3.
+AT_CHECK([ovs-appctl ofproto/trace br0 'in_port(3),eth(src=50:54:00:00:00:05,dst=50:54:00:00:00:06),eth_type(0x0800),ipv4(src=192.168.0.2,dst=192.168.0.1,proto=6,tos=0,ttl=64,frag=no),tcp(src=40000,dst=80)' -generate], [0], [stdout])
+AT_CHECK([tail -1 stdout], [0], [Datapath actions: 2,0,1
+])
+
+# Check for the learning entry.
+AT_CHECK([ovs-ofctl dump-flows br0 table=1 | ofctl_strip | sort], [0], [dnl
+ table=1, hard_timeout=60,tcp,nw_src=192.168.0.1,nw_dst=192.168.0.2,tp_src=80,tp_dst=40000 actions=drop
+NXST_FLOW reply:
+])
+OVS_VSWITCHD_STOP
+AT_CLEANUP
+
+AT_SETUP([learning action - TCPv6 port learning])
+OVS_VSWITCHD_START(
+  [add-port br0 eth0 -- set Interface eth0 type=dummy -- \
+   add-port br0 eth1 -- set Interface eth1 type=dummy -- \
+   add-port br0 eth2 -- set Interface eth2 type=dummy])
+# Set up flow table for TCPv6 port learning.
+AT_CHECK([[ovs-ofctl add-flow br0 'table=0 tcp6 actions=learn(table=1, hard_timeout=60, eth_type=0x86dd, nw_proto=6, NXM_NX_IPV6_SRC[]=NXM_NX_IPV6_DST[], NXM_NX_IPV6_DST[]=NXM_NX_IPV6_SRC[], NXM_OF_TCP_SRC[]=NXM_OF_TCP_DST[], NXM_OF_TCP_DST[]=NXM_OF_TCP_SRC[]), flood']])
+
+# Trace a TCPv6 packet arriving on port 3.
+AT_CHECK([ovs-appctl ofproto/trace br0 'in_port(3),eth(src=50:54:00:00:00:05,dst=50:54:00:00:00:06),eth_type(0x86dd),ipv6(src=fec0::2,dst=fec0::1,label=0,proto=6,tclass=0,hlimit=255,frag=no),tcp(src=40000,dst=80)' -generate], [0], [stdout])
+AT_CHECK([tail -1 stdout], [0], [Datapath actions: 2,0,1
+])
+
+# Check for the learning entry.
+AT_CHECK([ovs-ofctl dump-flows br0 table=1 | ofctl_strip | sort], [0], [dnl
+ table=1, hard_timeout=60,tcp6,ipv6_src=fec0::1,ipv6_dst=fec0::2,tp_src=80,tp_dst=40000 actions=drop
+NXST_FLOW reply:
+])
+OVS_VSWITCHD_STOP
+AT_CLEANUP
+
 AT_SETUP([learning action - fin_timeout feature])
 # This is a totally artificial use of the "learn" action.  The only purpose
 # is to check that specifying fin_idle_timeout or fin_hard_timeout causes