evaluate: reset statement length context before evaluating statement

This patch consolidates ctx->stmt_len reset in stmt_evaluate() to avoid
this problem. Note that stmt_evaluate_meta() and stmt_evaluate_ct()
already reset it after the statement evaluation.

Moreover, statement dependency can be generated while evaluating a meta
and ct statement. Payload statement dependency already manually stashes
this before calling stmt_evaluate(). Add a new stmt_dependency_evaluate()
function to stash statement length context when evaluating a new statement
dependency and use it for all of the existing statement dependencies.

Florian also says:

'meta mark set vlan id map { 1 : 0x00000001, 4095 : 0x00004095 }' will
crash. Reason is that the l2 dependency generated here is errounously
expanded to a 32bit-one, so the evaluation path won't recognize this
as a L2 dependency.  Therefore, pctx->stacked_ll_count is 0 and
__expr_evaluate_payload() crashes with a null deref when
dereferencing pctx->stacked_ll[0].

nft-test.py gains a fugly hack to tolerate '!map typeof vlan id : meta mark'.
For more generic support we should find something more acceptable, e.g.

!map typeof( everything here is a key or data ) timeout ...

tests/py update and assert(pctx->stacked_ll_count) by Florian Westphal.

Fixes: edecd58755a8 ("evaluate: support shifts larger than the width of the left operand")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 13 insertions, 4 deletions

diff --git a/tests/py/nft-test.py b/tests/py/nft-test.py
index 9a25503d..a7d27c25 100755
--- a/tests/py/nft-test.py
+++ b/tests/py/nft-test.py
@@ -368,9 +368,9 @@ def set_add(s, test_result, filename, lineno):
             flags = "flags %s; " % flags
 
         if s.data == "":
-                cmd = "add set %s %s { type %s;%s %s}" % (table, s.name, s.type, s.timeout, flags)
+                cmd = "add set %s %s { %s;%s %s}" % (table, s.name, s.type, s.timeout, flags)
         else:
-                cmd = "add map %s %s { type %s : %s;%s %s}" % (table, s.name, s.type, s.data, s.timeout, flags)
+                cmd = "add map %s %s { %s : %s;%s %s}" % (table, s.name, s.type, s.data, s.timeout, flags)
 
         ret = execute_cmd(cmd, filename, lineno)
 
@@ -410,7 +410,7 @@ def map_add(s, test_result, filename, lineno):
         if flags != "":
             flags = "flags %s; " % flags
 
-        cmd = "add map %s %s { type %s : %s;%s %s}" % (table, s.name, s.type, s.data, s.timeout, flags)
+        cmd = "add map %s %s { %s : %s;%s %s}" % (table, s.name, s.type, s.data, s.timeout, flags)
 
         ret = execute_cmd(cmd, filename, lineno)
 
@@ -1144,11 +1144,16 @@ def set_process(set_line, filename, lineno):
 
     tokens = set_line[0].split(" ")
     set_name = tokens[0]
-    set_type = tokens[2]
+    parse_typeof = tokens[1] == "typeof"
+    set_type = tokens[1] + " " + tokens[2]
     set_data = ""
     set_flags = ""
 
     i = 3
+    if parse_typeof and tokens[i] == "id":
+        set_type += " " + tokens[i]
+        i += 1;
+
     while len(tokens) > i and tokens[i] == ".":
         set_type += " . " + tokens[i+1]
         i += 2
@@ -1157,6 +1162,10 @@ def set_process(set_line, filename, lineno):
         set_data = tokens[i+1]
         i += 2
 
+    if parse_typeof and tokens[i] == "mark":
+        set_data += " " + tokens[i]
+        i += 1;
+
     if len(tokens) == i+2 and tokens[i] == "timeout":
         timeout = "timeout " + tokens[i+1] + ";"
         i += 2