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netfilter: helper: Add the rcu lock when call __nf_conntrack_helper_find

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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@ikuai8.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Gao Feng 2017-03-29 19:11:27 +08:00 committed by Pablo Neira Ayuso
parent 97aae0df1d
commit 8b5995d063
2 changed files with 20 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
net/netfilter/nf_conntrack_helper.c
View File

@ -158,16 +158,25 @@ nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
{
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);

10
net/netfilter/nf_conntrack_netlink.c
View File

@ -3133,23 +3133,27 @@ ctnetlink_create_expect(struct net *net,
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 @@ ctnetlink_create_expect(struct net *net,
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;