On Mon, Feb 17, 2014 at 12:15:19PM +0100, Florian Westphal wrote:
> Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote:
> > > > I think we should always do the module autoloading for nf-nat and
> > > > nf-nat-ipvX modules depending on nf_ct_l3num(ct), then return EAGAIN
> > > > to give another retry. Now, this needs to happen in any case, not only
> > > > when calling ctnetlink_parse_nat_setup().
> > >
> > > Not sure what you mean. If we enter nf_nat_setup_info without ctnetlink
> > > involvement the nf-nat protocol should already be there (else, how can
> > > we end up in nf_nat_setup_info? NAT/MASQUERADE depends on nf-nat).
> > >
> > > What use-case did you have in mind? (or, to put it differently, where
> > > do you think the module probing logic should be)?
> >
> > If __nf_nat_l3proto_find returns NULL before trying to attach the null
> > binding, I think you should call the routine to autoload the modules
> > before returning EAGAIN.
> >
> > proto = __nf_nat_l3proto_find(nf_ct_l3num(ct));
> > if (proto == NULL) {
> > ... release locks
> > request_module(...);
> > ... acquire locks again
> > return -EAGAIN;
> > }
>
> The patch alters ctnetlink to call ctnetlink_parse_nat_setup even when
> NAT attr == NULL.
>
> nfnetlink_attach_null_binding() returns EAGAIN; this return value is
> propagated back to ctnetlink_parse_nat_setup.
>
> That will then request_module(), nfnetlink will replay the message.
>
> running
> conntrack -I -p tcp -s 1.1.1.1 -d 2.2.2.2 --timeout 100 --state \
> ESTABLISHED --sport 10 --dport 20
> on newly booted machine works, lsmod pre/post
> shows:
> +nf_conntrack_ipv4 14808 1
> +nf_defrag_ipv4 12702 1 nf_conntrack_ipv4
> +nf_nat_ipv4 13199 0
> +nf_nat 20926 1 nf_nat_ipv4
>
> Which is the desired behaviour afaiu.
Right, your patch looks good.
> [ If you think calling ctnetlink_parse_nat_setup with NULL attr
> is abuse, please let me know and I will try to come up with something
> different ]
I think we can simplify this, the nfnetlink_parse_nat_setup() hook
function is always called under rcu_read_lock. See patch attached.
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index bb322d0..b9f0e03 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1310,27 +1310,22 @@ ctnetlink_change_status(struct nf_conn *ct, const struct nlattr * const cda[])
}
static int
-ctnetlink_change_nat(struct nf_conn *ct, const struct nlattr * const cda[])
+ctnetlink_setup_nat(struct nf_conn *ct, const struct nlattr * const cda[])
{
#ifdef CONFIG_NF_NAT_NEEDED
int ret;
- if (cda[CTA_NAT_DST]) {
- ret = ctnetlink_parse_nat_setup(ct,
- NF_NAT_MANIP_DST,
- cda[CTA_NAT_DST]);
- if (ret < 0)
- return ret;
- }
- if (cda[CTA_NAT_SRC]) {
- ret = ctnetlink_parse_nat_setup(ct,
- NF_NAT_MANIP_SRC,
- cda[CTA_NAT_SRC]);
- if (ret < 0)
- return ret;
- }
- return 0;
+ ret = ctnetlink_parse_nat_setup(ct, NF_NAT_MANIP_DST,
+ cda[CTA_NAT_DST]);
+ if (ret < 0)
+ return ret;
+
+ ret = ctnetlink_parse_nat_setup(ct, NF_NAT_MANIP_SRC,
+ cda[CTA_NAT_SRC]);
+ return ret;
#else
+ if (!cda[CTA_NAT_DST] && !cda[CTA_NAT_SRC])
+ return 0;
return -EOPNOTSUPP;
#endif
}
@@ -1659,11 +1654,9 @@ ctnetlink_create_conntrack(struct net *net, u16 zone,
goto err2;
}
- if (cda[CTA_NAT_SRC] || cda[CTA_NAT_DST]) {
- err = ctnetlink_change_nat(ct, cda);
- if (err < 0)
- goto err2;
- }
+ err = ctnetlink_setup_nat(ct, cda);
+ if (err < 0)
+ goto err2;
nf_ct_acct_ext_add(ct, GFP_ATOMIC);
nf_ct_tstamp_ext_add(ct, GFP_ATOMIC);
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index d3f5cd6..52ca952 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -432,15 +432,15 @@ nf_nat_setup_info(struct nf_conn *ct,
}
EXPORT_SYMBOL(nf_nat_setup_info);
-unsigned int
-nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
+static unsigned int
+__nf_nat_alloc_null_binding(struct nf_conn *ct, enum nf_nat_manip_type manip)
{
/* Force range to this IP; let proto decide mapping for
* per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
* Use reply in case it's already been mangled (eg local packet).
*/
union nf_inet_addr ip =
- (HOOK2MANIP(hooknum) == NF_NAT_MANIP_SRC ?
+ (manip == NF_NAT_MANIP_SRC ?
ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3 :
ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3);
struct nf_nat_range range = {
@@ -448,7 +448,13 @@ nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
.min_addr = ip,
.max_addr = ip,
};
- return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
+ return nf_nat_setup_info(ct, &range, manip);
+}
+
+unsigned int
+nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
+{
+ return __nf_nat_alloc_null_binding(ct, HOOK2MANIP(hooknum));
}
EXPORT_SYMBOL_GPL(nf_nat_alloc_null_binding);
@@ -702,9 +708,9 @@ static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
static int
nfnetlink_parse_nat(const struct nlattr *nat,
- const struct nf_conn *ct, struct nf_nat_range *range)
+ const struct nf_conn *ct, struct nf_nat_range *range,
+ const struct nf_nat_l3proto *l3proto)
{
- const struct nf_nat_l3proto *l3proto;
struct nlattr *tb[CTA_NAT_MAX+1];
int err;
@@ -714,38 +720,46 @@ nfnetlink_parse_nat(const struct nlattr *nat,
if (err < 0)
return err;
- rcu_read_lock();
- l3proto = __nf_nat_l3proto_find(nf_ct_l3num(ct));
- if (l3proto == NULL) {
- err = -EAGAIN;
- goto out;
- }
err = l3proto->nlattr_to_range(tb, range);
if (err < 0)
- goto out;
+ return err;
if (!tb[CTA_NAT_PROTO])
- goto out;
+ return 0;
- err = nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
-out:
- rcu_read_unlock();
- return err;
+ return nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
}
+/* This function is called under rcu_read_lock() */
static int
nfnetlink_parse_nat_setup(struct nf_conn *ct,
enum nf_nat_manip_type manip,
const struct nlattr *attr)
{
struct nf_nat_range range;
+ const struct nf_nat_l3proto *l3proto;
int err;
- err = nfnetlink_parse_nat(attr, ct, &range);
+ /* Should not happen, restricted to creating new conntracks
+ * via ctnetlink.
+ */
+ if (WARN_ON_ONCE(nf_nat_initialized(ct, manip)))
+ return -EEXIST;
+
+ /* Make sure that L3 NAT is there by when we call nf_nat_setup_info to
+ * attach the null binding, otherwise this may oops.
+ */
+ l3proto = __nf_nat_l3proto_find(nf_ct_l3num(ct));
+ if (l3proto == NULL)
+ return -EAGAIN;
+
+ /* No NAT information has been passed, allocate the null-binding */
+ if (attr == NULL)
+ return __nf_nat_alloc_null_binding(ct, manip);
+
+ err = nfnetlink_parse_nat(attr, ct, &range, l3proto);
if (err < 0)
return err;
- if (nf_nat_initialized(ct, manip))
- return -EEXIST;
return nf_nat_setup_info(ct, &range, manip);
}
--
1.7.10.4
