path: root/iptables
diff options
authorPhil Sutter <>2021-02-19 16:54:57 +0100
committerPhil Sutter <>2021-03-09 09:27:17 +0100
commit330f5df03ad589b46865ceedf2a54cf10a4225ba (patch)
treef1884d4455cb5934037248e920dc3525af43b361 /iptables
parent5f1fcacebf9b4529950b6e3f88327049a0ea7cd2 (diff)
nft: Fix bitwise expression avoidance detection
Byte-boundary prefix detection was too sloppy: Any data following the first zero-byte was ignored. Add a follow-up loop making sure there are no stray bits in the designated host part. Fixes: 323259001d617 ("nft: Optimize class-based IP prefix matches") Signed-off-by: Phil Sutter <>
Diffstat (limited to 'iptables')
2 files changed, 27 insertions, 1 deletions
diff --git a/iptables/nft-shared.c b/iptables/nft-shared.c
index 10553ab2..c1664b50 100644
--- a/iptables/nft-shared.c
+++ b/iptables/nft-shared.c
@@ -166,7 +166,7 @@ void add_addr(struct nftnl_rule *r, enum nft_payload_bases base, int offset,
const unsigned char *m = mask;
bool bitwise = false;
- int i;
+ int i, j;
for (i = 0; i < len; i++) {
if (m[i] != 0xff) {
@@ -174,6 +174,8 @@ void add_addr(struct nftnl_rule *r, enum nft_payload_bases base, int offset,
+ for (j = i + 1; !bitwise && j < len; j++)
+ bitwise = !!m[j];
if (!bitwise)
len = i;
diff --git a/iptables/tests/shell/testcases/ip6tables/0004-address-masks_0 b/iptables/tests/shell/testcases/ip6tables/0004-address-masks_0
new file mode 100755
index 00000000..7eb42f08
--- /dev/null
+++ b/iptables/tests/shell/testcases/ip6tables/0004-address-masks_0
@@ -0,0 +1,24 @@
+set -e
+$XT_MULTI ip6tables-restore <<EOF
+-A FORWARD -s feed:babe::/ffff::0
+-A FORWARD -s feed:babe::/ffff:ff00::0
+-A FORWARD -s feed:babe::/ffff:fff0::0
+-A FORWARD -s feed:babe::/ffff:ffff::0
+-A FORWARD -s feed:babe::/0:ffff::0
+-A FORWARD -s feed:c0ff::babe:f00/ffff::ffff:0
+-A FORWARD -s feed::/16
+-A FORWARD -s feed:ba00::/24
+-A FORWARD -s feed:bab0::/28
+-A FORWARD -s feed:babe::/32
+-A FORWARD -s 0:babe::/0:ffff::
+-A FORWARD -s feed::babe:0/ffff::ffff:0'
+diff -u -Z <(echo -e "$EXPECT") <($XT_MULTI ip6tables -S FORWARD)