tree 9c5e5cd835102d67198e5fd1c6756f3b0de65a2c
parent 31c913e7fd48000163a88cfe10383fd3be20910e
author Patrick McHardy <[EMAIL PROTECTED]> Wed, 07 Sep 2005 05:09:43 -0700
committer David S. Miller <[EMAIL PROTECTED]> Wed, 07 Sep 2005 05:09:43 -0700

[NETFILTER]: Handle NAT module load race

When the NAT module is loaded when connections are already confirmed
it must not change their tuples anymore. This is especially important
with CONFIG_NETFILTER_DEBUG, the netfilter listhelp functions will
refuse to remove an entry from a list when it can not be found on
the list, so when a changed tuple hashes to a new bucket the entry
is kept in the list until and after the conntrack is freed.

Allocate the exact conntrack tuple for NAT for already confirmed
connections or drop them if that fails.

Signed-off-by: Patrick McHardy <[EMAIL PROTECTED]>
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>

 include/linux/netfilter_ipv4/ip_nat_rule.h |    5 +++++
 net/ipv4/netfilter/ip_nat_rule.c           |   21 +++++++++++++++++++++
 net/ipv4/netfilter/ip_nat_standalone.c     |    8 ++++++--
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/include/linux/netfilter_ipv4/ip_nat_rule.h 
b/include/linux/netfilter_ipv4/ip_nat_rule.h
--- a/include/linux/netfilter_ipv4/ip_nat_rule.h
+++ b/include/linux/netfilter_ipv4/ip_nat_rule.h
@@ -19,5 +19,10 @@ extern unsigned int
 alloc_null_binding(struct ip_conntrack *conntrack,
                   struct ip_nat_info *info,
                   unsigned int hooknum);
+
+extern unsigned int
+alloc_null_binding_confirmed(struct ip_conntrack *conntrack,
+                            struct ip_nat_info *info,
+                            unsigned int hooknum);
 #endif
 #endif /* _IP_NAT_RULE_H */
diff --git a/net/ipv4/netfilter/ip_nat_rule.c b/net/ipv4/netfilter/ip_nat_rule.c
--- a/net/ipv4/netfilter/ip_nat_rule.c
+++ b/net/ipv4/netfilter/ip_nat_rule.c
@@ -255,6 +255,27 @@ alloc_null_binding(struct ip_conntrack *
        return ip_nat_setup_info(conntrack, &range, hooknum);
 }
 
+unsigned int
+alloc_null_binding_confirmed(struct ip_conntrack *conntrack,
+                             struct ip_nat_info *info,
+                             unsigned int hooknum)
+{
+       u_int32_t ip
+               = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
+                  ? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip
+                  : conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip);
+       u_int16_t all
+               = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
+                  ? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
+                  : conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
+       struct ip_nat_range range
+               = { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
+
+       DEBUGP("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
+              conntrack, NIPQUAD(ip));
+       return ip_nat_setup_info(conntrack, &range, hooknum);
+}
+
 int ip_nat_rule_find(struct sk_buff **pskb,
                     unsigned int hooknum,
                     const struct net_device *in,
diff --git a/net/ipv4/netfilter/ip_nat_standalone.c 
b/net/ipv4/netfilter/ip_nat_standalone.c
--- a/net/ipv4/netfilter/ip_nat_standalone.c
+++ b/net/ipv4/netfilter/ip_nat_standalone.c
@@ -123,8 +123,12 @@ ip_nat_fn(unsigned int hooknum,
                if (!ip_nat_initialized(ct, maniptype)) {
                        unsigned int ret;
 
-                       /* LOCAL_IN hook doesn't have a chain!  */
-                       if (hooknum == NF_IP_LOCAL_IN)
+                       if (unlikely(is_confirmed(ct)))
+                               /* NAT module was loaded late */
+                               ret = alloc_null_binding_confirmed(ct, info,
+                                                                  hooknum);
+                       else if (hooknum == NF_IP_LOCAL_IN)
+                               /* LOCAL_IN hook doesn't have a chain!  */
                                ret = alloc_null_binding(ct, info, hooknum);
                        else
                                ret = ip_nat_rule_find(pskb, hooknum,
-
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