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[NETFILTER]: nf_nat: don't add NAT extension for confirmed conntracks

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Adding extensions to confirmed conntracks is not allowed to avoid races
on reallocation. Don't setup NAT for confirmed conntracks in case NAT
module is loaded late.

The has one side-effect, the connections existing before the NAT module
was loaded won't enter the bysource hash. The only case where this actually
makes a difference is in case of SNAT to a multirange where the IP before
NAT is also part of the range. Since old connections don't enter the
bysource hash the first new connection from the IP will have a new address
selected. This shouldn't matter at all.

Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Patrick McHardy 2008-04-14 11:15:51 +02:00
parent 42cf800c24
commit 8c87238b72
3 changed files with 4 additions and 26 deletions
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3
include/net/netfilter/nf_nat_rule.h
View File

@ -14,7 +14,4 @@ extern int nf_nat_rule_find(struct sk_buff *skb,
extern unsigned int
alloc_null_binding(struct nf_conn *ct, unsigned int hooknum);
extern unsigned int
alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum);
#endif /* _NF_NAT_RULE_H */

19
net/ipv4/netfilter/nf_nat_rule.c
View File

@ -188,25 +188,6 @@ alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
}
unsigned int
alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum)
{
__be32 ip
= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
__be16 all
= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
struct nf_nat_range range
= { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
ct, NIPQUAD(ip));
return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
}
int nf_nat_rule_find(struct sk_buff *skb,
unsigned int hooknum,
const struct net_device *in,

8
net/ipv4/netfilter/nf_nat_standalone.c
View File

@ -102,6 +102,9 @@ nf_nat_fn(unsigned int hooknum,
nat = nfct_nat(ct);
if (!nat) {
/* NAT module was loaded late. */
if (nf_ct_is_confirmed(ct))
return NF_ACCEPT;
nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
if (nat == NULL) {
pr_debug("failed to add NAT extension\n");
@ -127,10 +130,7 @@ nf_nat_fn(unsigned int hooknum,
if (!nf_nat_initialized(ct, maniptype)) {
unsigned int ret;
if (unlikely(nf_ct_is_confirmed(ct)))
/* NAT module was loaded late */
ret = alloc_null_binding_confirmed(ct, hooknum);
else if (hooknum == NF_INET_LOCAL_IN)
if (hooknum == NF_INET_LOCAL_IN)
/* LOCAL_IN hook doesn't have a chain! */
ret = alloc_null_binding(ct, hooknum);
else