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authorEric Dumazet <eric.dumazet@gmail.com>2011-07-18 18:08:07 +0400
committerPatrick McHardy <kaber@trash.net>2011-07-18 18:08:07 +0400
commit6b75e3e8d664a9a1b99d31a7f4976ae70d1d090a (patch)
tree940d95c340df22db092062bdaea599e9afc4fcf9 /net
parent131ad62d8fc06d9d0a5c61d9526876352c2f2bbd (diff)
downloadlinux-6b75e3e8d664a9a1b99d31a7f4976ae70d1d090a.tar.xz
netfilter: nfnetlink: add RCU in nfnetlink_rcv_msg()
Goal of this patch is to permit nfnetlink providers not mandate nfnl_mutex being held while nfnetlink_rcv_msg() calls them. If struct nfnl_callback contains a non NULL call_rcu(), then nfnetlink_rcv_msg() will use it instead of call() field, holding rcu_read_lock instead of nfnl_mutex Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> CC: Florian Westphal <fw@strlen.de> CC: Eric Leblond <eric@regit.org> Signed-off-by: Patrick McHardy <kaber@trash.net>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nfnetlink.c40
1 files changed, 30 insertions, 10 deletions
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index b4a4532823e8..1905976b5135 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -37,7 +37,7 @@ MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
static char __initdata nfversion[] = "0.30";
-static const struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
+static const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT];
static DEFINE_MUTEX(nfnl_mutex);
void nfnl_lock(void)
@@ -59,7 +59,7 @@ int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
nfnl_unlock();
return -EBUSY;
}
- subsys_table[n->subsys_id] = n;
+ rcu_assign_pointer(subsys_table[n->subsys_id], n);
nfnl_unlock();
return 0;
@@ -71,7 +71,7 @@ int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
nfnl_lock();
subsys_table[n->subsys_id] = NULL;
nfnl_unlock();
-
+ synchronize_rcu();
return 0;
}
EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
@@ -83,7 +83,7 @@ static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t t
if (subsys_id >= NFNL_SUBSYS_COUNT)
return NULL;
- return subsys_table[subsys_id];
+ return rcu_dereference(subsys_table[subsys_id]);
}
static inline const struct nfnl_callback *
@@ -139,21 +139,27 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
type = nlh->nlmsg_type;
replay:
+ rcu_read_lock();
ss = nfnetlink_get_subsys(type);
if (!ss) {
#ifdef CONFIG_MODULES
- nfnl_unlock();
+ rcu_read_unlock();
request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
- nfnl_lock();
+ rcu_read_lock();
ss = nfnetlink_get_subsys(type);
if (!ss)
#endif
+ {
+ rcu_read_unlock();
return -EINVAL;
+ }
}
nc = nfnetlink_find_client(type, ss);
- if (!nc)
+ if (!nc) {
+ rcu_read_unlock();
return -EINVAL;
+ }
{
int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
@@ -167,7 +173,23 @@ replay:
if (err < 0)
return err;
- err = nc->call(net->nfnl, skb, nlh, (const struct nlattr **)cda);
+ if (nc->call_rcu) {
+ err = nc->call_rcu(net->nfnl, skb, nlh,
+ (const struct nlattr **)cda);
+ rcu_read_unlock();
+ } else {
+ rcu_read_unlock();
+ nfnl_lock();
+ if (rcu_dereference_protected(
+ subsys_table[NFNL_SUBSYS_ID(type)],
+ lockdep_is_held(&nfnl_mutex)) != ss ||
+ nfnetlink_find_client(type, ss) != nc)
+ err = -EAGAIN;
+ else
+ err = nc->call(net->nfnl, skb, nlh,
+ (const struct nlattr **)cda);
+ nfnl_unlock();
+ }
if (err == -EAGAIN)
goto replay;
return err;
@@ -176,9 +198,7 @@ replay:
static void nfnetlink_rcv(struct sk_buff *skb)
{
- nfnl_lock();
netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
- nfnl_unlock();
}
static int __net_init nfnetlink_net_init(struct net *net)