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linux-next/net/sched/act_simple.c
Davide Caratti 85d0966fa5 net/sched: prepare TC actions to properly validate the control action
- pass a pointer to struct tcf_proto in each actions's init() handler,
  to allow validating the control action, checking whether the chain
  exists and (eventually) refcounting it.
- remove code that validates the control action after a successful call
  to the action's init() handler, and replace it with a test that forbids
  addition of actions having 'goto_chain' and NULL goto_chain pointer at
  the same time.
- add tcf_action_check_ctrlact(), that will validate the control action
  and eventually allocate the action 'goto_chain' within the init()
  handler.
- add tcf_action_set_ctrlact(), that will assign the control action and
  swap the current 'goto_chain' pointer with the new given one.

This disallows 'goto_chain' on actions that don't initialize it properly
in their init() handler, i.e. calling tcf_action_check_ctrlact() after
successful IDR reservation and then calling tcf_action_set_ctrlact()
to assign 'goto_chain' and 'tcf_action' consistently.

By doing this, the kernel does not leak anymore refcounts when a valid
'goto chain' handle is replaced in TC actions, causing kmemleak splats
like the following one:

 # tc chain add dev dd0 chain 42 ingress protocol ip flower \
 > ip_proto tcp action drop
 # tc chain add dev dd0 chain 43 ingress protocol ip flower \
 > ip_proto udp action drop
 # tc filter add dev dd0 ingress matchall \
 > action gact goto chain 42 index 66
 # tc filter replace dev dd0 ingress matchall \
 > action gact goto chain 43 index 66
 # echo scan >/sys/kernel/debug/kmemleak
 <...>
 unreferenced object 0xffff93c0ee09f000 (size 1024):
 comm "tc", pid 2565, jiffies 4295339808 (age 65.426s)
 hex dump (first 32 bytes):
   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   00 00 00 00 08 00 06 00 00 00 00 00 00 00 00 00  ................
 backtrace:
   [<000000009b63f92d>] tc_ctl_chain+0x3d2/0x4c0
   [<00000000683a8d72>] rtnetlink_rcv_msg+0x263/0x2d0
   [<00000000ddd88f8e>] netlink_rcv_skb+0x4a/0x110
   [<000000006126a348>] netlink_unicast+0x1a0/0x250
   [<00000000b3340877>] netlink_sendmsg+0x2c1/0x3c0
   [<00000000a25a2171>] sock_sendmsg+0x36/0x40
   [<00000000f19ee1ec>] ___sys_sendmsg+0x280/0x2f0
   [<00000000d0422042>] __sys_sendmsg+0x5e/0xa0
   [<000000007a6c61f9>] do_syscall_64+0x5b/0x180
   [<00000000ccd07542>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
   [<0000000013eaa334>] 0xffffffffffffffff

Fixes: db50514f9a ("net: sched: add termination action to allow goto chain")
Fixes: 97763dc0f4 ("net_sched: reject unknown tcfa_action values")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-03-21 13:26:41 -07:00

247 lines
6.0 KiB
C

/*
* net/sched/act_simple.c Simple example of an action
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: Jamal Hadi Salim (2005-8)
*
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <linux/tc_act/tc_defact.h>
#include <net/tc_act/tc_defact.h>
static unsigned int simp_net_id;
static struct tc_action_ops act_simp_ops;
#define SIMP_MAX_DATA 32
static int tcf_simp_act(struct sk_buff *skb, const struct tc_action *a,
struct tcf_result *res)
{
struct tcf_defact *d = to_defact(a);
spin_lock(&d->tcf_lock);
tcf_lastuse_update(&d->tcf_tm);
bstats_update(&d->tcf_bstats, skb);
/* print policy string followed by _ then packet count
* Example if this was the 3rd packet and the string was "hello"
* then it would look like "hello_3" (without quotes)
*/
pr_info("simple: %s_%d\n",
(char *)d->tcfd_defdata, d->tcf_bstats.packets);
spin_unlock(&d->tcf_lock);
return d->tcf_action;
}
static void tcf_simp_release(struct tc_action *a)
{
struct tcf_defact *d = to_defact(a);
kfree(d->tcfd_defdata);
}
static int alloc_defdata(struct tcf_defact *d, const struct nlattr *defdata)
{
d->tcfd_defdata = kzalloc(SIMP_MAX_DATA, GFP_KERNEL);
if (unlikely(!d->tcfd_defdata))
return -ENOMEM;
nla_strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
return 0;
}
static void reset_policy(struct tcf_defact *d, const struct nlattr *defdata,
struct tc_defact *p)
{
spin_lock_bh(&d->tcf_lock);
d->tcf_action = p->action;
memset(d->tcfd_defdata, 0, SIMP_MAX_DATA);
nla_strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
spin_unlock_bh(&d->tcf_lock);
}
static const struct nla_policy simple_policy[TCA_DEF_MAX + 1] = {
[TCA_DEF_PARMS] = { .len = sizeof(struct tc_defact) },
[TCA_DEF_DATA] = { .type = NLA_STRING, .len = SIMP_MAX_DATA },
};
static int tcf_simp_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, struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, simp_net_id);
struct nlattr *tb[TCA_DEF_MAX + 1];
struct tc_defact *parm;
struct tcf_defact *d;
bool exists = false;
int ret = 0, err;
if (nla == NULL)
return -EINVAL;
err = nla_parse_nested(tb, TCA_DEF_MAX, nla, simple_policy, NULL);
if (err < 0)
return err;
if (tb[TCA_DEF_PARMS] == NULL)
return -EINVAL;
parm = nla_data(tb[TCA_DEF_PARMS]);
err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
if (err < 0)
return err;
exists = err;
if (exists && bind)
return 0;
if (tb[TCA_DEF_DATA] == NULL) {
if (exists)
tcf_idr_release(*a, bind);
else
tcf_idr_cleanup(tn, parm->index);
return -EINVAL;
}
if (!exists) {
ret = tcf_idr_create(tn, parm->index, est, a,
&act_simp_ops, bind, false);
if (ret) {
tcf_idr_cleanup(tn, parm->index);
return ret;
}
d = to_defact(*a);
ret = alloc_defdata(d, tb[TCA_DEF_DATA]);
if (ret < 0) {
tcf_idr_release(*a, bind);
return ret;
}
d->tcf_action = parm->action;
ret = ACT_P_CREATED;
} else {
d = to_defact(*a);
if (!ovr) {
tcf_idr_release(*a, bind);
return -EEXIST;
}
reset_policy(d, tb[TCA_DEF_DATA], parm);
}
if (ret == ACT_P_CREATED)
tcf_idr_insert(tn, *a);
return ret;
}
static int tcf_simp_dump(struct sk_buff *skb, struct tc_action *a,
int bind, int ref)
{
unsigned char *b = skb_tail_pointer(skb);
struct tcf_defact *d = to_defact(a);
struct tc_defact opt = {
.index = d->tcf_index,
.refcnt = refcount_read(&d->tcf_refcnt) - ref,
.bindcnt = atomic_read(&d->tcf_bindcnt) - bind,
};
struct tcf_t t;
spin_lock_bh(&d->tcf_lock);
opt.action = d->tcf_action;
if (nla_put(skb, TCA_DEF_PARMS, sizeof(opt), &opt) ||
nla_put_string(skb, TCA_DEF_DATA, d->tcfd_defdata))
goto nla_put_failure;
tcf_tm_dump(&t, &d->tcf_tm);
if (nla_put_64bit(skb, TCA_DEF_TM, sizeof(t), &t, TCA_DEF_PAD))
goto nla_put_failure;
spin_unlock_bh(&d->tcf_lock);
return skb->len;
nla_put_failure:
spin_unlock_bh(&d->tcf_lock);
nlmsg_trim(skb, b);
return -1;
}
static int tcf_simp_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, simp_net_id);
return tcf_generic_walker(tn, skb, cb, type, ops, extack);
}
static int tcf_simp_search(struct net *net, struct tc_action **a, u32 index)
{
struct tc_action_net *tn = net_generic(net, simp_net_id);
return tcf_idr_search(tn, a, index);
}
static struct tc_action_ops act_simp_ops = {
.kind = "simple",
.id = TCA_ID_SIMP,
.owner = THIS_MODULE,
.act = tcf_simp_act,
.dump = tcf_simp_dump,
.cleanup = tcf_simp_release,
.init = tcf_simp_init,
.walk = tcf_simp_walker,
.lookup = tcf_simp_search,
.size = sizeof(struct tcf_defact),
};
static __net_init int simp_init_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, simp_net_id);
return tc_action_net_init(tn, &act_simp_ops);
}
static void __net_exit simp_exit_net(struct list_head *net_list)
{
tc_action_net_exit(net_list, simp_net_id);
}
static struct pernet_operations simp_net_ops = {
.init = simp_init_net,
.exit_batch = simp_exit_net,
.id = &simp_net_id,
.size = sizeof(struct tc_action_net),
};
MODULE_AUTHOR("Jamal Hadi Salim(2005)");
MODULE_DESCRIPTION("Simple example action");
MODULE_LICENSE("GPL");
static int __init simp_init_module(void)
{
int ret = tcf_register_action(&act_simp_ops, &simp_net_ops);
if (!ret)
pr_info("Simple TC action Loaded\n");
return ret;
}
static void __exit simp_cleanup_module(void)
{
tcf_unregister_action(&act_simp_ops, &simp_net_ops);
}
module_init(simp_init_module);
module_exit(simp_cleanup_module);