From a441dfdbb2e54217b8d26a6c129650728d401bf7 Mon Sep 17 00:00:00 2001
From: Patrick McHardy <kaber@trash.net>
Date: Mon, 12 Feb 2007 11:12:09 -0800
Subject: [NETFILTER]: ip_nat: properly use RCU API for ip_nat_protos array
Replace preempt_{enable,disable} based RCU by proper use of the
RCU API and add missing rcu_read_lock/rcu_read_unlock calls in
paths used outside of packet processing context (nfnetlink_conntrack).
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/netfilter/ip_nat_core.c | 61 +++++++++++++++++++---------------------
1 file changed, 29 insertions(+), 32 deletions(-)
(limited to 'net')
diff --git a/net/ipv4/netfilter/ip_nat_core.c b/net/ipv4/netfilter/ip_nat_core.c
index 275a4d3faf0a..85ae0cabc8b5 100644
--- a/net/ipv4/netfilter/ip_nat_core.c
+++ b/net/ipv4/netfilter/ip_nat_core.c
@@ -50,7 +50,7 @@ static struct ip_nat_protocol *ip_nat_protos[MAX_IP_NAT_PROTO];
static inline struct ip_nat_protocol *
__ip_nat_proto_find(u_int8_t protonum)
{
- return ip_nat_protos[protonum];
+ return rcu_dereference(ip_nat_protos[protonum]);
}
struct ip_nat_protocol *
@@ -58,13 +58,11 @@ ip_nat_proto_find_get(u_int8_t protonum)
{
struct ip_nat_protocol *p;
- /* we need to disable preemption to make sure 'p' doesn't get
- * removed until we've grabbed the reference */
- preempt_disable();
+ rcu_read_lock();
p = __ip_nat_proto_find(protonum);
if (!try_module_get(p->me))
p = &ip_nat_unknown_protocol;
- preempt_enable();
+ rcu_read_unlock();
return p;
}
@@ -120,8 +118,8 @@ static int
in_range(const struct ip_conntrack_tuple *tuple,
const struct ip_nat_range *range)
{
- struct ip_nat_protocol *proto =
- __ip_nat_proto_find(tuple->dst.protonum);
+ struct ip_nat_protocol *proto;
+ int ret = 0;
/* If we are supposed to map IPs, then we must be in the
range specified, otherwise let this drag us onto a new src IP. */
@@ -131,12 +129,15 @@ in_range(const struct ip_conntrack_tuple *tuple,
return 0;
}
+ rcu_read_lock();
+ proto = __ip_nat_proto_find(tuple->dst.protonum);
if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)
|| proto->in_range(tuple, IP_NAT_MANIP_SRC,
&range->min, &range->max))
- return 1;
+ ret = 1;
+ rcu_read_unlock();
- return 0;
+ return ret;
}
static inline int
@@ -260,27 +261,25 @@ get_unique_tuple(struct ip_conntrack_tuple *tuple,
/* 3) The per-protocol part of the manip is made to map into
the range to make a unique tuple. */
- proto = ip_nat_proto_find_get(orig_tuple->dst.protonum);
+ rcu_read_lock();
+ proto = __ip_nat_proto_find(orig_tuple->dst.protonum);
/* Change protocol info to have some randomization */
if (range->flags & IP_NAT_RANGE_PROTO_RANDOM) {
proto->unique_tuple(tuple, range, maniptype, conntrack);
- ip_nat_proto_put(proto);
- return;
+ goto out;
}
/* Only bother mapping if it's not already in range and unique */
if ((!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)
|| proto->in_range(tuple, maniptype, &range->min, &range->max))
- && !ip_nat_used_tuple(tuple, conntrack)) {
- ip_nat_proto_put(proto);
- return;
- }
+ && !ip_nat_used_tuple(tuple, conntrack))
+ goto out;
/* Last change: get protocol to try to obtain unique tuple. */
proto->unique_tuple(tuple, range, maniptype, conntrack);
-
- ip_nat_proto_put(proto);
+out:
+ rcu_read_unlock();
}
unsigned int
@@ -360,12 +359,11 @@ manip_pkt(u_int16_t proto,
iph = (void *)(*pskb)->data + iphdroff;
/* Manipulate protcol part. */
- p = ip_nat_proto_find_get(proto);
- if (!p->manip_pkt(pskb, iphdroff, target, maniptype)) {
- ip_nat_proto_put(p);
+
+ /* rcu_read_lock()ed by nf_hook_slow */
+ p = __ip_nat_proto_find(proto);
+ if (!p->manip_pkt(pskb, iphdroff, target, maniptype))
return 0;
- }
- ip_nat_proto_put(p);
iph = (void *)(*pskb)->data + iphdroff;
@@ -515,7 +513,7 @@ int ip_nat_protocol_register(struct ip_nat_protocol *proto)
ret = -EBUSY;
goto out;
}
- ip_nat_protos[proto->protonum] = proto;
+ rcu_assign_pointer(ip_nat_protos[proto->protonum], proto);
out:
write_unlock_bh(&ip_nat_lock);
return ret;
@@ -526,11 +524,10 @@ EXPORT_SYMBOL(ip_nat_protocol_register);
void ip_nat_protocol_unregister(struct ip_nat_protocol *proto)
{
write_lock_bh(&ip_nat_lock);
- ip_nat_protos[proto->protonum] = &ip_nat_unknown_protocol;
+ rcu_assign_pointer(ip_nat_protos[proto->protonum],
+ &ip_nat_unknown_protocol);
write_unlock_bh(&ip_nat_lock);
-
- /* Someone could be still looking at the proto in a bh. */
- synchronize_net();
+ synchronize_rcu();
}
EXPORT_SYMBOL(ip_nat_protocol_unregister);
@@ -594,10 +591,10 @@ static int __init ip_nat_init(void)
/* Sew in builtin protocols. */
write_lock_bh(&ip_nat_lock);
for (i = 0; i < MAX_IP_NAT_PROTO; i++)
- ip_nat_protos[i] = &ip_nat_unknown_protocol;
- ip_nat_protos[IPPROTO_TCP] = &ip_nat_protocol_tcp;
- ip_nat_protos[IPPROTO_UDP] = &ip_nat_protocol_udp;
- ip_nat_protos[IPPROTO_ICMP] = &ip_nat_protocol_icmp;
+ rcu_assign_pointer(ip_nat_protos[i], &ip_nat_unknown_protocol);
+ rcu_assign_pointer(ip_nat_protos[IPPROTO_TCP], &ip_nat_protocol_tcp);
+ rcu_assign_pointer(ip_nat_protos[IPPROTO_UDP], &ip_nat_protocol_udp);
+ rcu_assign_pointer(ip_nat_protos[IPPROTO_ICMP], &ip_nat_protocol_icmp);
write_unlock_bh(&ip_nat_lock);
for (i = 0; i < ip_nat_htable_size; i++) {
--
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