Commit 544d5c7d authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso

netfilter: ctnetlink: allow to set expectfn for expectations

This patch allows you to set expectfn which is specifically used
by the NAT side of most of the existing conntrack helpers.

I have added a symbol map that uses a string as key to look up for
the function that is attached to the expectation object. This is
the best solution I came out with to solve this issue.
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 076a0ca0
......@@ -175,6 +175,7 @@ enum ctattr_expect {
CTA_EXPECT_FLAGS,
CTA_EXPECT_CLASS,
CTA_EXPECT_NAT,
CTA_EXPECT_FN,
__CTA_EXPECT_MAX
};
#define CTA_EXPECT_MAX (__CTA_EXPECT_MAX - 1)
......
......@@ -69,4 +69,17 @@ extern int nf_conntrack_broadcast_help(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
unsigned int timeout);
struct nf_ct_helper_expectfn {
struct list_head head;
const char *name;
void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
};
void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_name(const char *name);
struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
#endif /*_NF_CONNTRACK_HELPER_H*/
......@@ -686,6 +686,11 @@ static struct pernet_operations nf_nat_net_ops = {
.exit = nf_nat_net_exit,
};
static struct nf_ct_helper_expectfn follow_master_nat = {
.name = "nat-follow-master",
.expectfn = nf_nat_follow_master,
};
static int __init nf_nat_init(void)
{
size_t i;
......@@ -717,6 +722,8 @@ static int __init nf_nat_init(void)
l3proto = nf_ct_l3proto_find_get((u_int16_t)AF_INET);
nf_ct_helper_expectfn_register(&follow_master_nat);
BUG_ON(nf_nat_seq_adjust_hook != NULL);
RCU_INIT_POINTER(nf_nat_seq_adjust_hook, nf_nat_seq_adjust);
BUG_ON(nfnetlink_parse_nat_setup_hook != NULL);
......@@ -736,6 +743,7 @@ static void __exit nf_nat_cleanup(void)
unregister_pernet_subsys(&nf_nat_net_ops);
nf_ct_l3proto_put(l3proto);
nf_ct_extend_unregister(&nat_extend);
nf_ct_helper_expectfn_unregister(&follow_master_nat);
RCU_INIT_POINTER(nf_nat_seq_adjust_hook, NULL);
RCU_INIT_POINTER(nfnetlink_parse_nat_setup_hook, NULL);
RCU_INIT_POINTER(nf_ct_nat_offset, NULL);
......
......@@ -568,6 +568,16 @@ static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
return 0;
}
static struct nf_ct_helper_expectfn q931_nat = {
.name = "Q.931",
.expectfn = ip_nat_q931_expect,
};
static struct nf_ct_helper_expectfn callforwarding_nat = {
.name = "callforwarding",
.expectfn = ip_nat_callforwarding_expect,
};
/****************************************************************************/
static int __init init(void)
{
......@@ -590,6 +600,8 @@ static int __init init(void)
RCU_INIT_POINTER(nat_h245_hook, nat_h245);
RCU_INIT_POINTER(nat_callforwarding_hook, nat_callforwarding);
RCU_INIT_POINTER(nat_q931_hook, nat_q931);
nf_ct_helper_expectfn_register(&q931_nat);
nf_ct_helper_expectfn_register(&callforwarding_nat);
return 0;
}
......@@ -605,6 +617,8 @@ static void __exit fini(void)
RCU_INIT_POINTER(nat_h245_hook, NULL);
RCU_INIT_POINTER(nat_callforwarding_hook, NULL);
RCU_INIT_POINTER(nat_q931_hook, NULL);
nf_ct_helper_expectfn_unregister(&q931_nat);
nf_ct_helper_expectfn_unregister(&callforwarding_nat);
synchronize_rcu();
}
......
......@@ -526,6 +526,11 @@ static unsigned int ip_nat_sdp_media(struct sk_buff *skb, unsigned int dataoff,
return NF_DROP;
}
static struct nf_ct_helper_expectfn sip_nat = {
.name = "sip",
.expectfn = ip_nat_sip_expected,
};
static void __exit nf_nat_sip_fini(void)
{
RCU_INIT_POINTER(nf_nat_sip_hook, NULL);
......@@ -535,6 +540,7 @@ static void __exit nf_nat_sip_fini(void)
RCU_INIT_POINTER(nf_nat_sdp_port_hook, NULL);
RCU_INIT_POINTER(nf_nat_sdp_session_hook, NULL);
RCU_INIT_POINTER(nf_nat_sdp_media_hook, NULL);
nf_ct_helper_expectfn_unregister(&sip_nat);
synchronize_rcu();
}
......@@ -554,6 +560,7 @@ static int __init nf_nat_sip_init(void)
RCU_INIT_POINTER(nf_nat_sdp_port_hook, ip_nat_sdp_port);
RCU_INIT_POINTER(nf_nat_sdp_session_hook, ip_nat_sdp_session);
RCU_INIT_POINTER(nf_nat_sdp_media_hook, ip_nat_sdp_media);
nf_ct_helper_expectfn_register(&sip_nat);
return 0;
}
......
......@@ -181,6 +181,60 @@ void nf_ct_helper_destroy(struct nf_conn *ct)
}
}
static LIST_HEAD(nf_ct_helper_expectfn_list);
void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
{
spin_lock_bh(&nf_conntrack_lock);
list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
spin_unlock_bh(&nf_conntrack_lock);
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
{
spin_lock_bh(&nf_conntrack_lock);
list_del_rcu(&n->head);
spin_unlock_bh(&nf_conntrack_lock);
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
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);
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);
int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
{
unsigned int h = helper_hash(&me->tuple);
......
......@@ -1679,6 +1679,8 @@ ctnetlink_exp_dump_expect(struct sk_buff *skb,
struct nlattr *nest_parms;
struct nf_conntrack_tuple nat_tuple = {};
#endif
struct nf_ct_helper_expectfn *expfn;
if (timeout < 0)
timeout = 0;
......@@ -1722,6 +1724,9 @@ ctnetlink_exp_dump_expect(struct sk_buff *skb,
if (helper)
NLA_PUT_STRING(skb, CTA_EXPECT_HELP_NAME, helper->name);
}
expfn = nf_ct_helper_expectfn_find_by_symbol(exp->expectfn);
if (expfn != NULL)
NLA_PUT_STRING(skb, CTA_EXPECT_FN, expfn->name);
return 0;
......@@ -1881,6 +1886,7 @@ static const struct nla_policy exp_nla_policy[CTA_EXPECT_MAX+1] = {
[CTA_EXPECT_FLAGS] = { .type = NLA_U32 },
[CTA_EXPECT_CLASS] = { .type = NLA_U32 },
[CTA_EXPECT_NAT] = { .type = NLA_NESTED },
[CTA_EXPECT_FN] = { .type = NLA_NUL_STRING },
};
static int
......@@ -2182,9 +2188,20 @@ ctnetlink_create_expect(struct net *net, u16 zone,
} else
exp->flags = 0;
}
if (cda[CTA_EXPECT_FN]) {
const char *name = nla_data(cda[CTA_EXPECT_FN]);
struct nf_ct_helper_expectfn *expfn;
exp->class = class;
expfn = nf_ct_helper_expectfn_find_by_name(name);
if (expfn == NULL) {
err = -EINVAL;
goto err_out;
}
exp->expectfn = expfn->expectfn;
} else
exp->expectfn = NULL;
exp->class = class;
exp->master = ct;
exp->helper = helper;
memcpy(&exp->tuple, &tuple, sizeof(struct nf_conntrack_tuple));
......
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