[PATCH 5.16 040/285] ipv6: make mc_forwarding atomic

Greg Kroah-Hartman
2022-04-12T07:49:48Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 145c7a793838add5e004e7d49a67654dc7eba147 ]

This fixes minor data-races in ip6_mc_input() and
batadv_mcast_mla_rtr_flags_softif_get_ipv6()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/ipv6.h | 2 +-
net/batman-adv/multicast.c | 2 +-
net/ipv6/addrconf.c | 4 ++--
net/ipv6/ip6_input.c | 2 +-
net/ipv6/ip6mr.c | 8 ++++----
5 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index a59d25f19385..b8641dc0ee66 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -51,7 +51,7 @@ struct ipv6_devconf {
__s32 use_optimistic;
#endif
#ifdef CONFIG_IPV6_MROUTE
- __s32 mc_forwarding;
+ atomic_t mc_forwarding;
#endif
__s32 disable_ipv6;
__s32 drop_unicast_in_l2_multicast;
diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index f4004cf0ff6f..9f311fddfaf9 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -134,7 +134,7 @@ static u8 batadv_mcast_mla_rtr_flags_softif_get_ipv6(struct net_device *dev)
{
struct inet6_dev *in6_dev = __in6_dev_get(dev);

- if (in6_dev && in6_dev->cnf.mc_forwarding)
+ if (in6_dev && atomic_read(&in6_dev->cnf.mc_forwarding))
return BATADV_NO_FLAGS;
else
return BATADV_MCAST_WANT_NO_RTR6;
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index e92ca415756a..4f64fb285af7 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -554,7 +554,7 @@ static int inet6_netconf_fill_devconf(struct sk_buff *skb, int ifindex,
#ifdef CONFIG_IPV6_MROUTE
if ((all || type == NETCONFA_MC_FORWARDING) &&
nla_put_s32(skb, NETCONFA_MC_FORWARDING,
- devconf->mc_forwarding) < 0)
+ atomic_read(&devconf->mc_forwarding)) < 0)
goto nla_put_failure;
#endif
if ((all || type == NETCONFA_PROXY_NEIGH) &&
@@ -5539,7 +5539,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
array[DEVCONF_USE_OPTIMISTIC] = cnf->use_optimistic;
#endif
#ifdef CONFIG_IPV6_MROUTE
- array[DEVCONF_MC_FORWARDING] = cnf->mc_forwarding;
+ array[DEVCONF_MC_FORWARDING] = atomic_read(&cnf->mc_forwarding);
#endif
array[DEVCONF_DISABLE_IPV6] = cnf->disable_ipv6;
array[DEVCONF_ACCEPT_DAD] = cnf->accept_dad;
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 80256717868e..d4b1e2c5aa76 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -508,7 +508,7 @@ int ip6_mc_input(struct sk_buff *skb)
/*
* IPv6 multicast router mode is now supported ;)
*/
- if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
+ if (atomic_read(&dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding) &&
!(ipv6_addr_type(&hdr->daddr) &
(IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 6a4065d81aa9..91f1c5f56d5f 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -739,7 +739,7 @@ static int mif6_delete(struct mr_table *mrt, int vifi, int notify,

in6_dev = __in6_dev_get(dev);
if (in6_dev) {
- in6_dev->cnf.mc_forwarding--;
+ atomic_dec(&in6_dev->cnf.mc_forwarding);
inet6_netconf_notify_devconf(dev_net(dev), RTM_NEWNETCONF,
NETCONFA_MC_FORWARDING,
dev->ifindex, &in6_dev->cnf);
@@ -907,7 +907,7 @@ static int mif6_add(struct net *net, struct mr_table *mrt,

in6_dev = __in6_dev_get(dev);
if (in6_dev) {
- in6_dev->cnf.mc_forwarding++;
+ atomic_inc(&in6_dev->cnf.mc_forwarding);
inet6_netconf_notify_devconf(dev_net(dev), RTM_NEWNETCONF,
NETCONFA_MC_FORWARDING,
dev->ifindex, &in6_dev->cnf);
@@ -1557,7 +1557,7 @@ static int ip6mr_sk_init(struct mr_table *mrt, struct sock *sk)
} else {
rcu_assign_pointer(mrt->mroute_sk, sk);
sock_set_flag(sk, SOCK_RCU_FREE);
- net->ipv6.devconf_all->mc_forwarding++;
+ atomic_inc(&net->ipv6.devconf_all->mc_forwarding);
}
write_unlock_bh(&mrt_lock);

@@ -1590,7 +1590,7 @@ int ip6mr_sk_done(struct sock *sk)
* so the RCU grace period before sk freeing
* is guaranteed by sk_destruct()
*/
- net->ipv6.devconf_all->mc_forwarding--;
+ atomic_dec(&net->ipv6.devconf_all->mc_forwarding);
write_unlock_bh(&mrt_lock);
inet6_netconf_notify_devconf(net, RTM_NEWNETCONF,
NETCONFA_MC_FORWARDING,
--
2.35.1