netfilter: {ip, ip6, arp}_tables: fix incorrect loop detection

upstream commit: 1f9352ae2253a97b07b34dcf16ffa3b4ca12c558

Commit e1b4b9f ([NETFILTER]: {ip,ip6,arp}_tables: fix exponential worst-case
search for loops) introduced a regression in the loop detection algorithm,
causing sporadic incorrectly detected loops.

When a chain has already been visited during the check, it is treated as
having a standard target containing a RETURN verdict directly at the
beginning in order to not check it again. The real target of the first
rule is then incorrectly treated as STANDARD target and checked not to
contain invalid verdicts.

Fix by making sure the rule does actually contain a standard target.

Based on patch by Francis Dupont <Francis_Dupont@isc.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 7ea88b61cb0dd7d854c8e46e029ec3dcb40f057c..39879aef9e4e302c931da133c9a601492b59ddbe 100644 (file)
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -374,7 +374,9 @@ static int mark_source_chains(struct xt_table_info *newinfo,
                            && unconditional(&e->arp)) || visited) {
                                unsigned int oldpos, size;
 
-                               if (t->verdict < -NF_MAX_VERDICT - 1) {
+                               if ((strcmp(t->target.u.user.name,
+                                           ARPT_STANDARD_TARGET) == 0) &&
+                                   t->verdict < -NF_MAX_VERDICT - 1) {
                                        duprintf("mark_source_chains: bad "
                                                "negative verdict (%i)\n",
                                                                t->verdict);

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index ef8b6ca068b280aabe538d58af8da7c580d09b2b..ec362a344f05235ad504e4d53323a3046c45eb4a 100644 (file)
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -496,7 +496,9 @@ mark_source_chains(struct xt_table_info *newinfo,
                            && unconditional(&e->ip)) || visited) {
                                unsigned int oldpos, size;
 
-                               if (t->verdict < -NF_MAX_VERDICT - 1) {
+                               if ((strcmp(t->target.u.user.name,
+                                           IPT_STANDARD_TARGET) == 0) &&
+                                   t->verdict < -NF_MAX_VERDICT - 1) {
                                        duprintf("mark_source_chains: bad "
                                                "negative verdict (%i)\n",
                                                                t->verdict);

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index a33485dc81cb107e1cc343a764126325c9db2c05..def375b7fad588790214510f1142c64d6fd94ed4 100644 (file)
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -525,7 +525,9 @@ mark_source_chains(struct xt_table_info *newinfo,
                            && unconditional(&e->ipv6)) || visited) {
                                unsigned int oldpos, size;
 
-                               if (t->verdict < -NF_MAX_VERDICT - 1) {
+                               if ((strcmp(t->target.u.user.name,
+                                           IP6T_STANDARD_TARGET) == 0) &&
+                                   t->verdict < -NF_MAX_VERDICT - 1) {
                                        duprintf("mark_source_chains: bad "
                                                "negative verdict (%i)\n",
                                                                t->verdict);