evaluate: reset statement length context only for set mappings

map expression (which is used a key to look up for the mapping) needs to
consider the statement length context, otherwise incorrect bytecode is
generated when {ct,meta} statement is generated.

 # nft -f - <<EOF
 add table ip6 t
 add chain ip6 t c
 add map ip6 t mapv6 { typeof ip6 dscp : meta mark; }
 EOF

 # nft -d netlink add rule ip6 t c meta mark set ip6 dscp map @mapv6
 ip6 t c
   [ payload load 2b @ network header + 0 => reg 1 ]
   [ bitwise reg 1 = ( reg 1 & 0x0000c00f ) ^ 0x00000000 ]
   ... missing byteorder conversion here before shift ...
   [ bitwise reg 1 = ( reg 1 >> 0x00000006 ) ]
   [ lookup reg 1 set mapv6 dreg 1 ]
   [ meta set mark with reg 1 ]

Reset statement length context only for the mapping side for the
elements in the set.

Fixes: edecd58755a8 ("evaluate: support shifts larger than the width of the left operand")
Reported-by: Brian Davidson <davidson.brian@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 58 insertions, 0 deletions

diff --git a/tests/py/ip6/ip6.t.json b/tests/py/ip6/ip6.t.json
index cf802175..5411190d 100644
--- a/tests/py/ip6/ip6.t.json
+++ b/tests/py/ip6/ip6.t.json
@@ -135,6 +135,64 @@
     }
 ]
 
+# meta mark set ip6 dscp map @map1
+[
+    {
+        "mangle": {
+            "key": {
+                "meta": {
+                    "key": "mark"
+                }
+            },
+            "value": {
+                "map": {
+                    "data": "@map1",
+                    "key": {
+                        "payload": {
+                            "field": "dscp",
+                            "protocol": "ip6"
+                        }
+                    }
+                }
+            }
+        }
+    }
+]
+
+# meta mark set ip6 dscp . ip6 daddr map @map2
+[
+    {
+        "mangle": {
+            "key": {
+                "meta": {
+                    "key": "mark"
+                }
+            },
+            "value": {
+                "map": {
+                    "data": "@map2",
+                    "key": {
+                        "concat": [
+                            {
+                                "payload": {
+                                    "field": "dscp",
+                                    "protocol": "ip6"
+                                }
+                            },
+                            {
+                                "payload": {
+                                    "field": "daddr",
+                                    "protocol": "ip6"
+                                }
+                            }
+                        ]
+                    }
+                }
+            }
+        }
+    }
+]
+
 # ip6 flowlabel 22
 [
     {