pneigh_enqueue() tries to obtain a random delay by mod
NEIGH_VAR(p, PROXY_DELAY). However, NEIGH_VAR(p, PROXY_DELAY)
migth be zero at that point because someone could write zero
to /proc/sys/net/ipv4/neigh/[device]/proxy_delay after the
callers check it.
This patch makes pneigh_enqueue() get a delay time passed in
by the callers and the callers guarantee it is not zero.
Signed-off-by: weichenchen <weichen.c...@linux.alibaba.com>
---
V3:
- Callers need to pass the delay time to pneigh_enqueue()
now and they should guarantee it is not zero.
- Use READ_ONCE() to read NEIGH_VAR(p, PROXY_DELAY) in both
of the existing callers of pneigh_enqueue() and then pass
it to pneigh_enqueue().
V2:
- Use READ_ONCE() to prevent the complier from re-reading
NEIGH_VAR(p, PROXY_DELAY).
- Give a hint to the complier that delay <= 0 is unlikely
to happen.
---
include/net/neighbour.h | 2 +-
net/core/neighbour.c | 5 ++---
net/ipv4/arp.c | 8 +++++---
net/ipv6/ndisc.c | 6 +++---
4 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 22ced1381ede..f7564dc5304d 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -352,7 +352,7 @@ struct net *neigh_parms_net(const struct neigh_parms *parms)
unsigned long neigh_rand_reach_time(unsigned long base);
void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
- struct sk_buff *skb);
+ struct sk_buff *skb, int delay);
struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net,
const void *key, struct net_device *dev,
int creat);
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 9500d28a43b0..b440f966d109 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1567,12 +1567,11 @@ static void neigh_proxy_process(struct timer_list *t)
}
void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
- struct sk_buff *skb)
+ struct sk_buff *skb, int delay)
{
unsigned long now = jiffies;
- unsigned long sched_next = now + (prandom_u32() %
- NEIGH_VAR(p, PROXY_DELAY));
+ unsigned long sched_next = now + (prandom_u32() % delay);
if (tbl->proxy_queue.qlen > NEIGH_VAR(p, PROXY_QLEN)) {
kfree_skb(skb);
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 922dd73e5740..6ddce6e0a648 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -841,20 +841,22 @@ static int arp_process(struct net *net, struct sock *sk,
struct sk_buff *skb)
arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
(rt->dst.dev != dev &&
pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
+ int delay;
+
n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
if (n)
neigh_release(n);
+ delay = READ_ONCE(NEIGH_VAR(in_dev->arp_parms,
PROXY_DELAY));
if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
- skb->pkt_type == PACKET_HOST ||
- NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY)
== 0) {
+ skb->pkt_type == PACKET_HOST || delay == 0)
{
arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
sip, dev, tip, sha,
dev->dev_addr, sha,
reply_dst);
} else {
pneigh_enqueue(&arp_tbl,
- in_dev->arp_parms, skb);
+ in_dev->arp_parms, skb,
delay);
goto out_free_dst;
}
goto out_consume_skb;
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 76717478f173..efdaaab47535 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -892,10 +892,10 @@ static void ndisc_recv_ns(struct sk_buff *skb)
(idev->cnf.forwarding &&
(net->ipv6.devconf_all->proxy_ndp || idev->cnf.proxy_ndp)
&&
(is_router = pndisc_is_router(&msg->target, dev)) >= 0)) {
+ int delay = READ_ONCE(NEIGH_VAR(idev->nd_parms,
PROXY_DELAY));
if (!(NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED) &&
skb->pkt_type != PACKET_HOST &&
- inc &&
- NEIGH_VAR(idev->nd_parms, PROXY_DELAY) != 0) {
+ inc && delay != 0) {
/*
* for anycast or proxy,
* sender should delay its response
@@ -905,7 +905,7 @@ static void ndisc_recv_ns(struct sk_buff *skb)
*/
struct sk_buff *n = skb_clone(skb, GFP_ATOMIC);
if (n)
- pneigh_enqueue(&nd_tbl, idev->nd_parms,
n);
+ pneigh_enqueue(&nd_tbl, idev->nd_parms,
n, delay);
goto out;
}
} else
--
2.20.1 (Apple Git-117)
