[PATCH v3] libiptc: don't set_changed() when checking rules with module jumps

[Dan Williams <dcbw@xxxxxxxxxx>]

Checking a rule that includes a jump to a module-based target currently
sets the "changed" flag on the handle, which then causes TC_COMMIT() to
run through the whole SO_SET_REPLACE/SO_SET_ADD_COUNTERS path.  This
seems wrong for simply checking rules, an operation which is documented
as "...does not alter the existing iptables configuration..." but yet
it clearly could do so.

Fix that by ensuring that rule check operations for module targets
don't set the changed flag, and thus exit early from TC_COMMIT().

Signed-off-by: Dan Williams <dcbw@xxxxxxxxxx>
---
 libiptc/libiptc.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/libiptc/libiptc.c b/libiptc/libiptc.c
index 2c66d04..a6e7057 100644
--- a/libiptc/libiptc.c
+++ b/libiptc/libiptc.c
@@ -1686,7 +1686,8 @@ iptcc_standard_map(struct rule_head *r, int verdict)
 
 static int
 iptcc_map_target(struct xtc_handle *const handle,
-	   struct rule_head *r)
+	   struct rule_head *r,
+	   bool dry_run)
 {
 	STRUCT_ENTRY *e = r->entry;
 	STRUCT_ENTRY_TARGET *t = GET_TARGET(e);
@@ -1731,7 +1732,8 @@ iptcc_map_target(struct xtc_handle *const handle,
 	       0,
 	       FUNCTION_MAXNAMELEN - 1 - strlen(t->u.user.name));
 	r->type = IPTCC_R_MODULE;
-	set_changed(handle);
+	if (!dry_run)
+		set_changed(handle);
 	return 1;
 }
 
@@ -1781,7 +1783,7 @@ TC_INSERT_ENTRY(const IPT_CHAINLABEL chain,
 	memcpy(r->entry, e, e->next_offset);
 	r->counter_map.maptype = COUNTER_MAP_SET;
 
-	if (!iptcc_map_target(handle, r)) {
+	if (!iptcc_map_target(handle, r, false)) {
 		free(r);
 		return 0;
 	}
@@ -1831,7 +1833,7 @@ TC_REPLACE_ENTRY(const IPT_CHAINLABEL chain,
 	memcpy(r->entry, e, e->next_offset);
 	r->counter_map.maptype = COUNTER_MAP_SET;
 
-	if (!iptcc_map_target(handle, r)) {
+	if (!iptcc_map_target(handle, r, false)) {
 		free(r);
 		return 0;
 	}
@@ -1870,7 +1872,7 @@ TC_APPEND_ENTRY(const IPT_CHAINLABEL chain,
 	memcpy(r->entry, e, e->next_offset);
 	r->counter_map.maptype = COUNTER_MAP_SET;
 
-	if (!iptcc_map_target(handle, r)) {
+	if (!iptcc_map_target(handle, r, false)) {
 		DEBUGP("unable to map target of rule for chain `%s'\n", chain);
 		free(r);
 		return 0;
@@ -1976,7 +1978,7 @@ static int delete_entry(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *origfw,
 
 	memcpy(r->entry, origfw, origfw->next_offset);
 	r->counter_map.maptype = COUNTER_MAP_NOMAP;
-	if (!iptcc_map_target(handle, r)) {
+	if (!iptcc_map_target(handle, r, dry_run)) {
 		DEBUGP("unable to map target of rule for chain `%s'\n", chain);
 		free(r);
 		return 0;
-- 
2.9.3
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