From: Gao Feng <fgao@xxxxxxxxxx>
When invoke __nf_conntrack_helper_find, it needs the rcu lock to
protect the helper module which would not be unloaded.
Now there are two caller nf_conntrack_helper_try_module_get and
ctnetlink_create_expect which don't hold rcu lock. And the other
callers left like ctnetlink_change_helper, ctnetlink_create_conntrack,
and ctnetlink_glue_attach_expect, they already hold the rcu lock
or spin_lock_bh.
Remove the rcu lock in functions nf_ct_helper_expectfn_find_by_name
and nf_ct_helper_expectfn_find_by_symbol. Because they return one pointer
which needs rcu lock, so their caller should hold the rcu lock, not in
these two functions.
Signed-off-by: Gao Feng <fgao@xxxxxxxxxx>
---
v3: Merge another refine patch, remove useless rcu lock, per Pablo
v2: add the rcu lock in nf_conntrack_helper_try_module_get
v1: initial version
net/netfilter/nf_conntrack_helper.c | 17 ++++++++++++-----
net/netfilter/nf_conntrack_netlink.c | 10 ++++++++--
2 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 6dc44d9..4eeb341 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -158,16 +158,25 @@ struct nf_conntrack_helper *
{
struct nf_conntrack_helper *h;
+ rcu_read_lock();
+
h = __nf_conntrack_helper_find(name, l3num, protonum);
#ifdef CONFIG_MODULES
if (h == NULL) {
- if (request_module("nfct-helper-%s", name) == 0)
+ rcu_read_unlock();
+ if (request_module("nfct-helper-%s", name) == 0) {
+ rcu_read_lock();
h = __nf_conntrack_helper_find(name, l3num, protonum);
+ } else {
+ return h;
+ }
}
#endif
if (h != NULL && !try_module_get(h->me))
h = NULL;
+ rcu_read_unlock();
+
return h;
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
@@ -311,38 +320,36 @@ void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
+/* Caller should hold the rcu lock */
struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_name(const char *name)
{
struct nf_ct_helper_expectfn *cur;
bool found = false;
- rcu_read_lock();
list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
if (!strcmp(cur->name, name)) {
found = true;
break;
}
}
- rcu_read_unlock();
return found ? cur : NULL;
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
+/* Caller should hold the rcu lock */
struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
{
struct nf_ct_helper_expectfn *cur;
bool found = false;
- rcu_read_lock();
list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
if (cur->expectfn == symbol) {
found = true;
break;
}
}
- rcu_read_unlock();
return found ? cur : NULL;
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 6806b5e..f6d1d63 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -3133,23 +3133,27 @@ static int ctnetlink_del_expect(struct net *net, struct sock *ctnl,
return -ENOENT;
ct = nf_ct_tuplehash_to_ctrack(h);
+ rcu_read_lock();
if (cda[CTA_EXPECT_HELP_NAME]) {
const char *helpname = nla_data(cda[CTA_EXPECT_HELP_NAME]);
helper = __nf_conntrack_helper_find(helpname, u3,
nf_ct_protonum(ct));
if (helper == NULL) {
+ rcu_read_unlock();
#ifdef CONFIG_MODULES
if (request_module("nfct-helper-%s", helpname) < 0) {
err = -EOPNOTSUPP;
goto err_ct;
}
+ rcu_read_lock();
helper = __nf_conntrack_helper_find(helpname, u3,
nf_ct_protonum(ct));
if (helper) {
err = -EAGAIN;
- goto err_ct;
+ goto err_rcu;
}
+ rcu_read_unlock();
#endif
err = -EOPNOTSUPP;
goto err_ct;
@@ -3159,11 +3163,13 @@ static int ctnetlink_del_expect(struct net *net, struct sock *ctnl,
exp = ctnetlink_alloc_expect(cda, ct, helper, &tuple, &mask);
if (IS_ERR(exp)) {
err = PTR_ERR(exp);
- goto err_ct;
+ goto err_rcu;
}
err = nf_ct_expect_related_report(exp, portid, report);
nf_ct_expect_put(exp);
+err_rcu:
+ rcu_read_unlock();
err_ct:
nf_ct_put(ct);
return err;
--
1.9.1
--
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