pf: Support "return" statements in passing rules when they fail.

Normally pf rules are expected to do one of two things: pass the traffic or
block it. Blocking can be silent - "drop", or loud - "return", "return-rst",
"return-icmp". Yet there is a 3rd category of traffic passing through pf:
Packets matching a "pass" rule but when applying the rule fails. This happens
when redirection table is empty or when src node or state creation fails. Such
rules always fail silently without notifying the sender.

Allow users to configure this behaviour too, so that pf returns an error packet
in these cases.

PR:		226850
Submitted by:	Kajetan Staszkiewicz <vegeta tuxpowered.net>
MFC after:	1 week
Sponsored by:	InnoGames GmbH

1 files changed, 25 insertions, 3 deletions

diff --git a/sbin/pfctl/parse.y b/sbin/pfctl/parse.y
index c976358325e7..26d1dbb1a1ec 100644
--- a/sbin/pfctl/parse.y
+++ b/sbin/pfctl/parse.y
@@ -79,6 +79,7 @@ static u_int16_t	 returnicmpdefault =
 static u_int16_t	 returnicmp6default =
 			    (ICMP6_DST_UNREACH << 8) | ICMP6_DST_UNREACH_NOPORT;
 static int		 blockpolicy = PFRULE_DROP;
+static int		 failpolicy = PFRULE_DROP;
 static int		 require_order = 1;
 static int		 default_statelock;
 
@@ -455,8 +456,8 @@ int	parseport(char *, struct range *r, int);
 %token	MINTTL ERROR ALLOWOPTS FASTROUTE FILENAME ROUTETO DUPTO REPLYTO NO LABEL
 %token	NOROUTE URPFFAILED FRAGMENT USER GROUP MAXMSS MAXIMUM TTL TOS DROP TABLE
 %token	REASSEMBLE FRAGDROP FRAGCROP ANCHOR NATANCHOR RDRANCHOR BINATANCHOR
-%token	SET OPTIMIZATION TIMEOUT LIMIT LOGINTERFACE BLOCKPOLICY RANDOMID
-%token	REQUIREORDER SYNPROXY FINGERPRINTS NOSYNC DEBUG SKIP HOSTID
+%token	SET OPTIMIZATION TIMEOUT LIMIT LOGINTERFACE BLOCKPOLICY FAILPOLICY
+%token	RANDOMID REQUIREORDER SYNPROXY FINGERPRINTS NOSYNC DEBUG SKIP HOSTID
 %token	ANTISPOOF FOR INCLUDE
 %token	BITMASK RANDOM SOURCEHASH ROUNDROBIN STATICPORT PROBABILITY
 %token	ALTQ CBQ CODEL PRIQ HFSC FAIRQ BANDWIDTH TBRSIZE LINKSHARE REALTIME
@@ -640,6 +641,20 @@ option		: SET OPTIMIZATION STRING		{
 				YYERROR;
 			blockpolicy = PFRULE_RETURN;
 		}
+		| SET FAILPOLICY DROP	{
+			if (pf->opts & PF_OPT_VERBOSE)
+				printf("set fail-policy drop\n");
+			if (check_rulestate(PFCTL_STATE_OPTION))
+				YYERROR;
+			failpolicy = PFRULE_DROP;
+		}
+		| SET FAILPOLICY RETURN {
+			if (pf->opts & PF_OPT_VERBOSE)
+				printf("set fail-policy return\n");
+			if (check_rulestate(PFCTL_STATE_OPTION))
+				YYERROR;
+			failpolicy = PFRULE_RETURN;
+		}
 		| SET REQUIREORDER yesno {
 			if (pf->opts & PF_OPT_VERBOSE)
 				printf("set require-order %s\n",
@@ -2636,7 +2651,12 @@ probability	: STRING				{
 		;
 
 
-action		: PASS			{ $$.b1 = PF_PASS; $$.b2 = $$.w = 0; }
+action		: PASS 			{
+			$$.b1 = PF_PASS;
+			$$.b2 = failpolicy;
+			$$.w = returnicmpdefault;
+			$$.w2 = returnicmp6default;
+		}
 		| BLOCK blockspec	{ $$ = $2; $$.b1 = PF_DROP; }
 		;
 
@@ -5471,6 +5491,7 @@ lookup(char *s)
 		{ "drop",		DROP},
 		{ "drop-ovl",		FRAGDROP},
 		{ "dup-to",		DUPTO},
+		{ "fail-policy",	FAILPOLICY},
 		{ "fairq",		FAIRQ},
 		{ "fastroute",		FASTROUTE},
 		{ "file",		FILENAME},
@@ -5935,6 +5956,7 @@ parse_config(char *filename, struct pfctl *xpf)
 	returnicmp6default =
 	    (ICMP6_DST_UNREACH << 8) | ICMP6_DST_UNREACH_NOPORT;
 	blockpolicy = PFRULE_DROP;
+	failpolicy = PFRULE_DROP;
 	require_order = 1;
 
 	if ((file = pushfile(filename, 0)) == NULL) {