pknock: implement automatic closing

Added the optional "--autoclose" parameter (takes minutes) that
closes the pknock-opened rule in a specified time.

Signed-off-by: Jan Rafaj <jr+netfilter-devel@cedric.unob.cz>

extensions/pknock/libxt_pknock.c

@@ -21,8 +21,9 @@ static const struct option pknock_mt_opts[] = {
 	/* .name, .has_arg, .flag, .val */
 	{.name = "knockports",  .has_arg = true,  .val = 'k'},
 	{.name = "time",        .has_arg = true,  .val = 't'},
+	{.name = "autoclose",   .has_arg = true,  .val = 'a'},
 	{.name = "name",        .has_arg = true,  .val = 'n'},
-	{.name = "opensecret",  .has_arg = true,  .val = 'a'},
+	{.name = "opensecret",  .has_arg = true,  .val = 'o'},
 	{.name = "closesecret", .has_arg = true,  .val = 'z'},
 	{.name = "strict",      .has_arg = false, .val = 'x'},
 	{.name = "checkip",     .has_arg = false, .val = 'c'},
@@ -36,6 +37,9 @@ static void pknock_mt_help(void)
 			"Matches destination port(s).\n"
 		" --time seconds\n"
 			"Max allowed time between knocks.\n"
+		" --autoclose minutes\n"
+			"Time after which to automatically close opened\n"
+			"\t\t\t\t\tport(s).\n"
 		" --strict				"
 			"Knocks sequence must be exact.\n"
 		" --name rule_name			"
@@ -106,6 +110,7 @@ __pknock_parse(int c, char **argv, int invert, unsigned int *flags,
 {
 	const char *proto;
 	struct xt_pknock_mtinfo *info = (void *)(*match)->data;
+	unsigned int tmp;
 
 	switch (c) {
 	case 'k': /* --knockports */
@@ -131,6 +136,18 @@ __pknock_parse(int c, char **argv, int invert, unsigned int *flags,
 		*flags |= XT_PKNOCK_TIME;
 		break;
 
+        case 'a': /* --autoclose */
+		if (*flags & XT_PKNOCK_AUTOCLOSE)
+			xtables_error(PARAMETER_PROBLEM, PKNOCK
+				"cannot use --autoclose twice.\n");
+		if (!xtables_strtoui(optarg, NULL, &tmp, 0, ~0U))
+			xtables_param_act(XTF_BAD_VALUE, PKNOCK,
+				"--autoclose", optarg);
+                info->autoclose_time = tmp;
+                info->option |= XT_PKNOCK_AUTOCLOSE;
+                *flags |= XT_PKNOCK_AUTOCLOSE;
+                break;
+
 	case 'n': /* --name */
 		if (*flags & XT_PKNOCK_NAME)
 			xtables_error(PARAMETER_PROBLEM, PKNOCK
@@ -146,7 +163,7 @@ __pknock_parse(int c, char **argv, int invert, unsigned int *flags,
 #endif
 		break;
 
-	case 'a': /* --opensecret */
+	case 'o': /* --opensecret */
 		if (*flags & XT_PKNOCK_OPENSECRET)
 			xtables_error(PARAMETER_PROBLEM, PKNOCK
 				"cannot use --opensecret twice.\n");
@@ -236,6 +253,9 @@ static void pknock_mt_check(unsigned int flags)
 		if (flags & XT_PKNOCK_TIME)
 			xtables_error(PARAMETER_PROBLEM, PKNOCK
 				"cannot specify --time with --checkip.\n");
+		if (flags & XT_PKNOCK_AUTOCLOSE)
+			xtables_error(PARAMETER_PROBLEM, PKNOCK
+				"cannot specify --autoclose with --checkip.\n");
 	}
 }
 
@@ -254,6 +274,8 @@ static void pknock_mt_print(const void *ip,
 	}
 	if (info->option & XT_PKNOCK_TIME)
 		printf("time %ld ", (long)info->max_time);
+	if (info->option & XT_PKNOCK_AUTOCLOSE)
+		printf("autoclose %lu ", (unsigned long)info->autoclose_time);
 	if (info->option & XT_PKNOCK_NAME)
 		printf("name %s ", info->rule_name);
 	if (info->option & XT_PKNOCK_OPENSECRET)
@@ -279,6 +301,9 @@ static void pknock_mt_save(const void *ip, const struct xt_entry_match *match)
 	}
 	if (info->option & XT_PKNOCK_TIME)
 		printf("--time %ld ", (long)info->max_time);
+	if (info->option & XT_PKNOCK_AUTOCLOSE)
+		printf("--autoclose %lu ",
+		       (unsigned long)info->autoclose_time);
 	if (info->option & XT_PKNOCK_NAME)
 		printf("--name %s ", info->rule_name);
 	if (info->option & XT_PKNOCK_OPENSECRET)

extensions/pknock/xt_pknock.c

@@ -68,6 +68,7 @@ struct xt_pknock_rule {
 	struct list_head *peer_head;
 	struct proc_dir_entry *status_proc;
 	unsigned long max_time;
+	unsigned long autoclose_time;
 };
 
 /**
@@ -244,6 +245,7 @@ pknock_seq_show(struct seq_file *s, void *v)
 {
 	const struct list_head *pos, *n;
 	const struct peer *peer;
+	unsigned long time;
 	unsigned long expir_time;
 
 	const struct list_head *peer_head = v;
@@ -264,6 +266,15 @@ pknock_seq_show(struct seq_file *s, void *v)
 		seq_printf(s, "expir_time=%ld ", expir_time);
 		seq_printf(s, "accepted_knock_count=%lu ",
 			(unsigned long)peer->accepted_knock_count);
+		if (rule->autoclose_time != 0) {
+			time = 0;
+			if (time_before(get_seconds(), peer->login_sec +
+			    rule->autoclose_time * 60))
+				time = peer->login_sec +
+				       rule->autoclose_time * 60 -
+				       get_seconds();
+			seq_printf(s, "autoclose_time=%lu [secs] ", time);
+		}
 		seq_printf(s, "\n");
 	}
 
@@ -314,6 +325,19 @@ static void update_rule_timer(struct xt_pknock_rule *rule)
 	add_timer(&rule->timer);
 }
 
+/**
+ * @peer
+ * @autoclose_time
+ *
+ * Returns true if autoclose due, or false if still valid.
+ */
+static inline bool
+autoclose_time_passed(const struct peer *peer, unsigned int autoclose_time)
+{
+	return peer != NULL && autoclose_time != 0 && time_after(get_seconds(),
+	       peer->login_sec + autoclose_time * 60);
+}
+
 /**
  * @peer
  * @max_time
@@ -352,8 +376,10 @@ peer_gc(unsigned long r)
 	hashtable_for_each_safe(pos, n, rule->peer_head, peer_hashsize, i) {
 		peer = list_entry(pos, struct peer, head);
 
-		if (!has_logged_during_this_minute(peer) &&
+		if ((!has_logged_during_this_minute(peer) &&
-						is_time_exceeded(peer, rule->max_time))
+		    is_time_exceeded(peer, rule->max_time)) ||
+		    (peer->status == ST_ALLOWED &&
+		    autoclose_time_passed(peer, rule->autoclose_time)))
 		{
 			pk_debug("DESTROYED", peer);
 			list_del(pos);
@@ -440,9 +466,10 @@ add_rule(struct xt_pknock_mtinfo *info)
 	strncpy(rule->rule_name, info->rule_name, info->rule_name_len);
 	rule->rule_name_len = info->rule_name_len;
 
-	rule->ref_count	= 1;
+	rule->ref_count      = 1;
-	rule->max_time	= info->max_time;
+	rule->max_time       = info->max_time;
-	rule->peer_head = alloc_hashtable(peer_hashsize);
+	rule->autoclose_time = info->autoclose_time;
+	rule->peer_head      = alloc_hashtable(peer_hashsize);
 	if (rule->peer_head == NULL)
 		goto out;
 
@@ -994,7 +1021,7 @@ static bool pknock_mt(const struct sk_buff *skb,
 				}
 			}
 #endif
-				goto out;
+			goto out;
 		}
 
 		if (is_first_knock(peer, info, hdr.port)) {
@@ -1008,7 +1035,16 @@ static bool pknock_mt(const struct sk_buff *skb,
 	}
 
 out:
-	if (ret != 0)
+	/* Handle cur.peer matching and deletion after autoclose_time passed */
+	if (ret && autoclose_time_passed(peer, rule->autoclose_time)) {
+		pk_debug("AUTOCLOSE TIME PASSED => BLOCKED", peer);
+		ret = false;
+		if (iph->protocol == IPPROTO_TCP ||
+		    !has_logged_during_this_minute(peer))
+			remove_peer(peer);
+	}
+
+	if (ret)
 		pk_debug("PASS OK", peer);
 	spin_unlock_bh(&list_lock);
 	return ret;
@@ -1061,6 +1097,8 @@ static bool pknock_mt_check(const struct xt_mtchk_param *par)
 #endif
 		if (info->option & XT_PKNOCK_TIME)
 			RETURN_ERR("Can't specify --time with --checkip.\n");
+		if (info->option & XT_PKNOCK_AUTOCLOSE)
+			RETURN_ERR("Can't specify --autoclose with --checkip.\n");
 	}
 
 #ifdef PK_CRYPTO

extensions/pknock/xt_pknock.h

@@ -21,6 +21,7 @@ enum {
 	XT_PKNOCK_CHECKIP     = 1 << 4,
 	XT_PKNOCK_OPENSECRET  = 1 << 5,
 	XT_PKNOCK_CLOSESECRET = 1 << 6,
+	XT_PKNOCK_AUTOCLOSE   = 1 << 7,
 
 	/* Can never change these, as they are make up the user protocol. */
 	XT_PKNOCK_MAX_PORTS      = 15,
@@ -41,6 +42,7 @@ struct xt_pknock_mtinfo {
 	uint8_t	ports_count;	/* number of ports */
 	uint16_t	port[XT_PKNOCK_MAX_PORTS]; /* port[,port,port,...] */
 	uint32_t	max_time;	/* max matching time between ports */
+	uint32_t autoclose_time;
 };
 
 struct xt_pknock_nl_msg {