path: root/libxtables
diff options
authorPhil Sutter <>2019-02-04 21:52:53 +0100
committerFlorian Westphal <>2019-02-05 16:09:41 +0100
commit148131f20421046fea028e638581e938ec985783 (patch)
tree728ddd7426c7d2477c0a92e130b92cbb5259f066 /libxtables
parenta880cc28358a32f96467e248266973b6ab83f080 (diff)
xtables: Fix for false-positive rule matching
When comparing two rules with non-standard targets, differences in targets' payloads wasn't respected. The cause is a rather hideous one: Unlike xtables_find_match(), xtables_find_target() did not care whether the found target was already in use or not, so the same target instance was assigned to both rules and therefore payload comparison happened over the same memory location. With legacy iptables it is not possible to reuse a target: The only case where two rules (i.e., iptables_command_state instances) could exist at the same time is when comparing rules, but that's handled using libiptc. The above change clashes with ebtables-nft's reuse of target objects: While input parsing still just assigns the object from xtables_targets list, rule conversion from nftnl to iptables_command_state allocates new data. To fix this, make ebtables-nft input parsing use the common command_jump() routine instead of its own simplified copy. In turn, this also eliminates the ebtables-nft-specific variants of parse_target(), though with a slight change of behaviour: Names of user-defined chains are no longer allowed to contain up to 31 but merely 28 characters. Signed-off-by: Phil Sutter <> Signed-off-by: Florian Westphal <>
Diffstat (limited to 'libxtables')
1 files changed, 17 insertions, 1 deletions
diff --git a/libxtables/xtables.c b/libxtables/xtables.c
index ea9bb102..895f6988 100644
--- a/libxtables/xtables.c
+++ b/libxtables/xtables.c
@@ -756,8 +756,24 @@ xtables_find_target(const char *name, enum xtables_tryload tryload)
for (ptr = xtables_targets; ptr; ptr = ptr->next) {
- if (extension_cmp(name, ptr->name, ptr->family))
+ if (extension_cmp(name, ptr->name, ptr->family)) {
+ struct xtables_target *clone;
+ /* First target of this type: */
+ if (ptr->t == NULL)
+ break;
+ /* Second and subsequent clones */
+ clone = xtables_malloc(sizeof(struct xtables_target));
+ memcpy(clone, ptr, sizeof(struct xtables_target));
+ clone->udata = NULL;
+ clone->tflags = 0;
+ /* This is a clone: */
+ clone->next = clone;
+ ptr = clone;
+ }