netdev - [iproute PATCH 1/3] ss: Review ssfilter

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Message-Id: <20180814121808.24774-2-phil@nwl.cc>
Date:   Tue, 14 Aug 2018 14:18:06 +0200
From:   Phil Sutter <phil@....cc>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     netdev@...r.kernel.org, Samuel Mannehed <samuel@...dio.se>
Subject: [iproute PATCH 1/3] ss: Review ssfilter

The original problem was ssfilter rejecting single expressions if
enclosed in braces, such as:

| sport = 22 or ( dport = 22 )

This is fixed by allowing 'expr' to be an 'exprlist' enclosed in braces.
The no longer required recursion in 'exprlist' being an 'exprlist'
enclosed in braces is dropped.

In addition to that, a few other things are changed:

* Remove pointless 'null' prefix in 'appled' before 'exprlist'.
* For simple equals matches, '=' operator was required for ports but not
  allowed for hosts. Make this consistent by making '=' operator
  optional in both cases.

Reported-by: Samuel Mannehed <samuel@...dio.se>
Fixes: b2038cc0b2403 ("ssfilter: Eliminate shift/reduce conflicts")
Signed-off-by: Phil Sutter <phil@....cc>
---
 misc/ssfilter.y | 36 +++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/misc/ssfilter.y b/misc/ssfilter.y
index 88d4229a9b241..0413dddaa7584 100644
--- a/misc/ssfilter.y
+++ b/misc/ssfilter.y
@@ -42,24 +42,22 @@ static void yyerror(char *s)
 %nonassoc '!'
 
 %%
-applet: null exprlist
+applet: exprlist
         {
-                *yy_ret = $2;
-                $$ = $2;
+                *yy_ret = $1;
+                $$ = $1;
         }
         | null
         ;
+
 null:   /* NOTHING */ { $$ = NULL; }
         ;
+
 exprlist: expr
         | '!' expr
         {
                 $$ = alloc_node(SSF_NOT, $2);
         }
-        | '(' exprlist ')'
-        {
-                $$ = $2;
-        }
         | exprlist '|' expr
         {
                 $$ = alloc_node(SSF_OR, $1);
@@ -77,13 +75,21 @@ exprlist: expr
         }
         ;
 
-expr:	DCOND HOSTCOND
+eq:	'='
+	| /* nothing */
+	;
+
+expr:	'(' exprlist ')'
+	{
+		$$ = $2;
+	}
+	| DCOND eq HOSTCOND
         {
-		$$ = alloc_node(SSF_DCOND, $2);
+		$$ = alloc_node(SSF_DCOND, $3);
         }
-        | SCOND HOSTCOND
+        | SCOND eq HOSTCOND
         {
-		$$ = alloc_node(SSF_SCOND, $2);
+		$$ = alloc_node(SSF_SCOND, $3);
         }
         | DPORT GEQ HOSTCOND
         {
@@ -101,7 +107,7 @@ expr:	DCOND HOSTCOND
         {
                 $$ = alloc_node(SSF_NOT, alloc_node(SSF_D_GE, $3));
         }
-        | DPORT '=' HOSTCOND
+        | DPORT eq HOSTCOND
         {
 		$$ = alloc_node(SSF_DCOND, $3);
         }
@@ -126,7 +132,7 @@ expr:	DCOND HOSTCOND
         {
                 $$ = alloc_node(SSF_NOT, alloc_node(SSF_S_GE, $3));
         }
-        | SPORT '=' HOSTCOND
+        | SPORT eq HOSTCOND
         {
 		$$ = alloc_node(SSF_SCOND, $3);
         }
@@ -134,7 +140,7 @@ expr:	DCOND HOSTCOND
         {
 		$$ = alloc_node(SSF_NOT, alloc_node(SSF_SCOND, $3));
         }
-        | DEVNAME '=' DEVCOND
+        | DEVNAME eq DEVCOND
         {
 		$$ = alloc_node(SSF_DEVCOND, $3);
         }
@@ -142,7 +148,7 @@ expr:	DCOND HOSTCOND
         {
 		$$ = alloc_node(SSF_NOT, alloc_node(SSF_DEVCOND, $3));
         }
-        | FWMARK '=' MARKMASK
+        | FWMARK eq MARKMASK
         {
                 $$ = alloc_node(SSF_MARKMASK, $3);
         }
-- 
2.18.0