linux/net/sched/act_ipt.c
Cong Wang e49d8c22f1 net_sched: defer tcf_idr_insert() in tcf_action_init_1()
All TC actions call tcf_idr_insert() for new action at the end
of their ->init(), so we can actually move it to a central place
in tcf_action_init_1().

And once the action is inserted into the global IDR, other parallel
process could free it immediately as its refcnt is still 1, so we can
not fail after this, we need to move it after the goto action
validation to avoid handling the failure case after insertion.

This is found during code review, is not directly triggered by syzbot.
And this prepares for the next patch.

Cc: Vlad Buslov <vladbu@mellanox.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-09-24 19:46:21 -07:00

447 lines
10 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/sched/act_ipt.c iptables target interface
*
*TODO: Add other tables. For now we only support the ipv4 table targets
*
* Copyright: Jamal Hadi Salim (2002-13)
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <linux/tc_act/tc_ipt.h>
#include <net/tc_act/tc_ipt.h>
#include <linux/netfilter_ipv4/ip_tables.h>
static unsigned int ipt_net_id;
static struct tc_action_ops act_ipt_ops;
static unsigned int xt_net_id;
static struct tc_action_ops act_xt_ops;
static int ipt_init_target(struct net *net, struct xt_entry_target *t,
char *table, unsigned int hook)
{
struct xt_tgchk_param par;
struct xt_target *target;
struct ipt_entry e = {};
int ret = 0;
target = xt_request_find_target(AF_INET, t->u.user.name,
t->u.user.revision);
if (IS_ERR(target))
return PTR_ERR(target);
t->u.kernel.target = target;
memset(&par, 0, sizeof(par));
par.net = net;
par.table = table;
par.entryinfo = &e;
par.target = target;
par.targinfo = t->data;
par.hook_mask = hook;
par.family = NFPROTO_IPV4;
ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
if (ret < 0) {
module_put(t->u.kernel.target->me);
return ret;
}
return 0;
}
static void ipt_destroy_target(struct xt_entry_target *t, struct net *net)
{
struct xt_tgdtor_param par = {
.target = t->u.kernel.target,
.targinfo = t->data,
.family = NFPROTO_IPV4,
.net = net,
};
if (par.target->destroy != NULL)
par.target->destroy(&par);
module_put(par.target->me);
}
static void tcf_ipt_release(struct tc_action *a)
{
struct tcf_ipt *ipt = to_ipt(a);
if (ipt->tcfi_t) {
ipt_destroy_target(ipt->tcfi_t, a->idrinfo->net);
kfree(ipt->tcfi_t);
}
kfree(ipt->tcfi_tname);
}
static const struct nla_policy ipt_policy[TCA_IPT_MAX + 1] = {
[TCA_IPT_TABLE] = { .type = NLA_STRING, .len = IFNAMSIZ },
[TCA_IPT_HOOK] = { .type = NLA_U32 },
[TCA_IPT_INDEX] = { .type = NLA_U32 },
[TCA_IPT_TARG] = { .len = sizeof(struct xt_entry_target) },
};
static int __tcf_ipt_init(struct net *net, unsigned int id, struct nlattr *nla,
struct nlattr *est, struct tc_action **a,
const struct tc_action_ops *ops, int ovr, int bind,
struct tcf_proto *tp, u32 flags)
{
struct tc_action_net *tn = net_generic(net, id);
struct nlattr *tb[TCA_IPT_MAX + 1];
struct tcf_ipt *ipt;
struct xt_entry_target *td, *t;
char *tname;
bool exists = false;
int ret = 0, err;
u32 hook = 0;
u32 index = 0;
if (nla == NULL)
return -EINVAL;
err = nla_parse_nested_deprecated(tb, TCA_IPT_MAX, nla, ipt_policy,
NULL);
if (err < 0)
return err;
if (tb[TCA_IPT_INDEX] != NULL)
index = nla_get_u32(tb[TCA_IPT_INDEX]);
err = tcf_idr_check_alloc(tn, &index, a, bind);
if (err < 0)
return err;
exists = err;
if (exists && bind)
return 0;
if (tb[TCA_IPT_HOOK] == NULL || tb[TCA_IPT_TARG] == NULL) {
if (exists)
tcf_idr_release(*a, bind);
else
tcf_idr_cleanup(tn, index);
return -EINVAL;
}
td = (struct xt_entry_target *)nla_data(tb[TCA_IPT_TARG]);
if (nla_len(tb[TCA_IPT_TARG]) != td->u.target_size) {
if (exists)
tcf_idr_release(*a, bind);
else
tcf_idr_cleanup(tn, index);
return -EINVAL;
}
if (!exists) {
ret = tcf_idr_create(tn, index, est, a, ops, bind,
false, 0);
if (ret) {
tcf_idr_cleanup(tn, index);
return ret;
}
ret = ACT_P_CREATED;
} else {
if (bind)/* dont override defaults */
return 0;
if (!ovr) {
tcf_idr_release(*a, bind);
return -EEXIST;
}
}
hook = nla_get_u32(tb[TCA_IPT_HOOK]);
err = -ENOMEM;
tname = kmalloc(IFNAMSIZ, GFP_KERNEL);
if (unlikely(!tname))
goto err1;
if (tb[TCA_IPT_TABLE] == NULL ||
nla_strlcpy(tname, tb[TCA_IPT_TABLE], IFNAMSIZ) >= IFNAMSIZ)
strcpy(tname, "mangle");
t = kmemdup(td, td->u.target_size, GFP_KERNEL);
if (unlikely(!t))
goto err2;
err = ipt_init_target(net, t, tname, hook);
if (err < 0)
goto err3;
ipt = to_ipt(*a);
spin_lock_bh(&ipt->tcf_lock);
if (ret != ACT_P_CREATED) {
ipt_destroy_target(ipt->tcfi_t, net);
kfree(ipt->tcfi_tname);
kfree(ipt->tcfi_t);
}
ipt->tcfi_tname = tname;
ipt->tcfi_t = t;
ipt->tcfi_hook = hook;
spin_unlock_bh(&ipt->tcf_lock);
return ret;
err3:
kfree(t);
err2:
kfree(tname);
err1:
tcf_idr_release(*a, bind);
return err;
}
static int tcf_ipt_init(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action **a, int ovr,
int bind, bool rtnl_held, struct tcf_proto *tp,
u32 flags, struct netlink_ext_ack *extack)
{
return __tcf_ipt_init(net, ipt_net_id, nla, est, a, &act_ipt_ops, ovr,
bind, tp, flags);
}
static int tcf_xt_init(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action **a, int ovr,
int bind, bool unlocked, struct tcf_proto *tp,
u32 flags, struct netlink_ext_ack *extack)
{
return __tcf_ipt_init(net, xt_net_id, nla, est, a, &act_xt_ops, ovr,
bind, tp, flags);
}
static int tcf_ipt_act(struct sk_buff *skb, const struct tc_action *a,
struct tcf_result *res)
{
int ret = 0, result = 0;
struct tcf_ipt *ipt = to_ipt(a);
struct xt_action_param par;
struct nf_hook_state state = {
.net = dev_net(skb->dev),
.in = skb->dev,
.hook = ipt->tcfi_hook,
.pf = NFPROTO_IPV4,
};
if (skb_unclone(skb, GFP_ATOMIC))
return TC_ACT_UNSPEC;
spin_lock(&ipt->tcf_lock);
tcf_lastuse_update(&ipt->tcf_tm);
bstats_update(&ipt->tcf_bstats, skb);
/* yes, we have to worry about both in and out dev
* worry later - danger - this API seems to have changed
* from earlier kernels
*/
par.state = &state;
par.target = ipt->tcfi_t->u.kernel.target;
par.targinfo = ipt->tcfi_t->data;
ret = par.target->target(skb, &par);
switch (ret) {
case NF_ACCEPT:
result = TC_ACT_OK;
break;
case NF_DROP:
result = TC_ACT_SHOT;
ipt->tcf_qstats.drops++;
break;
case XT_CONTINUE:
result = TC_ACT_PIPE;
break;
default:
net_notice_ratelimited("tc filter: Bogus netfilter code %d assume ACCEPT\n",
ret);
result = TC_ACT_OK;
break;
}
spin_unlock(&ipt->tcf_lock);
return result;
}
static int tcf_ipt_dump(struct sk_buff *skb, struct tc_action *a, int bind,
int ref)
{
unsigned char *b = skb_tail_pointer(skb);
struct tcf_ipt *ipt = to_ipt(a);
struct xt_entry_target *t;
struct tcf_t tm;
struct tc_cnt c;
/* for simple targets kernel size == user size
* user name = target name
* for foolproof you need to not assume this
*/
spin_lock_bh(&ipt->tcf_lock);
t = kmemdup(ipt->tcfi_t, ipt->tcfi_t->u.user.target_size, GFP_ATOMIC);
if (unlikely(!t))
goto nla_put_failure;
c.bindcnt = atomic_read(&ipt->tcf_bindcnt) - bind;
c.refcnt = refcount_read(&ipt->tcf_refcnt) - ref;
strcpy(t->u.user.name, ipt->tcfi_t->u.kernel.target->name);
if (nla_put(skb, TCA_IPT_TARG, ipt->tcfi_t->u.user.target_size, t) ||
nla_put_u32(skb, TCA_IPT_INDEX, ipt->tcf_index) ||
nla_put_u32(skb, TCA_IPT_HOOK, ipt->tcfi_hook) ||
nla_put(skb, TCA_IPT_CNT, sizeof(struct tc_cnt), &c) ||
nla_put_string(skb, TCA_IPT_TABLE, ipt->tcfi_tname))
goto nla_put_failure;
tcf_tm_dump(&tm, &ipt->tcf_tm);
if (nla_put_64bit(skb, TCA_IPT_TM, sizeof(tm), &tm, TCA_IPT_PAD))
goto nla_put_failure;
spin_unlock_bh(&ipt->tcf_lock);
kfree(t);
return skb->len;
nla_put_failure:
spin_unlock_bh(&ipt->tcf_lock);
nlmsg_trim(skb, b);
kfree(t);
return -1;
}
static int tcf_ipt_walker(struct net *net, struct sk_buff *skb,
struct netlink_callback *cb, int type,
const struct tc_action_ops *ops,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, ipt_net_id);
return tcf_generic_walker(tn, skb, cb, type, ops, extack);
}
static int tcf_ipt_search(struct net *net, struct tc_action **a, u32 index)
{
struct tc_action_net *tn = net_generic(net, ipt_net_id);
return tcf_idr_search(tn, a, index);
}
static struct tc_action_ops act_ipt_ops = {
.kind = "ipt",
.id = TCA_ID_IPT,
.owner = THIS_MODULE,
.act = tcf_ipt_act,
.dump = tcf_ipt_dump,
.cleanup = tcf_ipt_release,
.init = tcf_ipt_init,
.walk = tcf_ipt_walker,
.lookup = tcf_ipt_search,
.size = sizeof(struct tcf_ipt),
};
static __net_init int ipt_init_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, ipt_net_id);
return tc_action_net_init(net, tn, &act_ipt_ops);
}
static void __net_exit ipt_exit_net(struct list_head *net_list)
{
tc_action_net_exit(net_list, ipt_net_id);
}
static struct pernet_operations ipt_net_ops = {
.init = ipt_init_net,
.exit_batch = ipt_exit_net,
.id = &ipt_net_id,
.size = sizeof(struct tc_action_net),
};
static int tcf_xt_walker(struct net *net, struct sk_buff *skb,
struct netlink_callback *cb, int type,
const struct tc_action_ops *ops,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, xt_net_id);
return tcf_generic_walker(tn, skb, cb, type, ops, extack);
}
static int tcf_xt_search(struct net *net, struct tc_action **a, u32 index)
{
struct tc_action_net *tn = net_generic(net, xt_net_id);
return tcf_idr_search(tn, a, index);
}
static struct tc_action_ops act_xt_ops = {
.kind = "xt",
.id = TCA_ID_XT,
.owner = THIS_MODULE,
.act = tcf_ipt_act,
.dump = tcf_ipt_dump,
.cleanup = tcf_ipt_release,
.init = tcf_xt_init,
.walk = tcf_xt_walker,
.lookup = tcf_xt_search,
.size = sizeof(struct tcf_ipt),
};
static __net_init int xt_init_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, xt_net_id);
return tc_action_net_init(net, tn, &act_xt_ops);
}
static void __net_exit xt_exit_net(struct list_head *net_list)
{
tc_action_net_exit(net_list, xt_net_id);
}
static struct pernet_operations xt_net_ops = {
.init = xt_init_net,
.exit_batch = xt_exit_net,
.id = &xt_net_id,
.size = sizeof(struct tc_action_net),
};
MODULE_AUTHOR("Jamal Hadi Salim(2002-13)");
MODULE_DESCRIPTION("Iptables target actions");
MODULE_LICENSE("GPL");
MODULE_ALIAS("act_xt");
static int __init ipt_init_module(void)
{
int ret1, ret2;
ret1 = tcf_register_action(&act_xt_ops, &xt_net_ops);
if (ret1 < 0)
pr_err("Failed to load xt action\n");
ret2 = tcf_register_action(&act_ipt_ops, &ipt_net_ops);
if (ret2 < 0)
pr_err("Failed to load ipt action\n");
if (ret1 < 0 && ret2 < 0) {
return ret1;
} else
return 0;
}
static void __exit ipt_cleanup_module(void)
{
tcf_unregister_action(&act_ipt_ops, &ipt_net_ops);
tcf_unregister_action(&act_xt_ops, &xt_net_ops);
}
module_init(ipt_init_module);
module_exit(ipt_cleanup_module);