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Message-ID: <20250616233417.1153427-10-kuni1840@gmail.com>
Date: Mon, 16 Jun 2025 16:28:38 -0700
From: Kuniyuki Iwashima <kuni1840@...il.com>
To: "David S. Miller" <davem@...emloft.net>,
David Ahern <dsahern@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>,
Kuniyuki Iwashima <kuniyu@...gle.com>,
Kuniyuki Iwashima <kuni1840@...il.com>,
netdev@...r.kernel.org
Subject: [PATCH v1 net-next 09/15] ipv6: mcast: Don't hold RTNL for MCAST_ socket options.
From: Kuniyuki Iwashima <kuniyu@...gle.com>
In ip6_mc_source() and ip6_mc_msfilter(), per-socket mld data is
protected by lock_sock() and inet6_dev->mc_lock is also held for
some per-interface functions.
ip6_mc_find_dev_rtnl() only depends on RTNL. If we want to remove
it, we need to check inet6_dev->dead under mc_lock to close the race
with addrconf_ifdown(), as mentioned earlier.
Let's do that and drop RTNL for the rest of MCAST_ socket options.
Note that ip6_mc_msfilter() has unnecessary lock dances and they
are integrated into one to avoid the last-minute error and simplify
the error handling.
Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
---
net/ipv6/ipv6_sockglue.c | 5 ---
net/ipv6/mcast.c | 67 ++++++++++++++++++++++++----------------
2 files changed, 40 insertions(+), 32 deletions(-)
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index c8892d54821f..0c870713b08c 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -123,11 +123,6 @@ static bool setsockopt_needs_rtnl(int optname)
case IPV6_ADDRFORM:
case IPV6_JOIN_ANYCAST:
case IPV6_LEAVE_ANYCAST:
- case MCAST_JOIN_SOURCE_GROUP:
- case MCAST_LEAVE_SOURCE_GROUP:
- case MCAST_BLOCK_SOURCE:
- case MCAST_UNBLOCK_SOURCE:
- case MCAST_MSFILTER:
return true;
}
return false;
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 84c7ed23bc2d..fd0cab5066bb 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -300,31 +300,33 @@ int ipv6_sock_mc_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
}
EXPORT_SYMBOL(ipv6_sock_mc_drop);
-static struct inet6_dev *ip6_mc_find_dev_rtnl(struct net *net,
- const struct in6_addr *group,
- int ifindex)
+static struct inet6_dev *ip6_mc_find_dev(struct net *net,
+ const struct in6_addr *group,
+ int ifindex)
{
struct net_device *dev = NULL;
- struct inet6_dev *idev = NULL;
+ struct inet6_dev *idev;
if (ifindex == 0) {
struct rt6_info *rt = rt6_lookup(net, group, NULL, 0, NULL, 0);
if (rt) {
dev = rt->dst.dev;
+ dev_hold(dev);
ip6_rt_put(rt);
}
} else {
- dev = __dev_get_by_index(net, ifindex);
+ dev = dev_get_by_index(net, ifindex);
}
-
if (!dev)
return NULL;
- idev = __in6_dev_get(dev);
+
+ idev = in6_dev_get(dev);
+ dev_put(dev);
+
if (!idev)
return NULL;
- if (idev->dead)
- return NULL;
+
return idev;
}
@@ -352,16 +354,16 @@ void ipv6_sock_mc_close(struct sock *sk)
}
int ip6_mc_source(int add, int omode, struct sock *sk,
- struct group_source_req *pgsr)
+ struct group_source_req *pgsr)
{
+ struct ipv6_pinfo *inet6 = inet6_sk(sk);
struct in6_addr *source, *group;
+ struct net *net = sock_net(sk);
struct ipv6_mc_socklist *pmc;
- struct inet6_dev *idev;
- struct ipv6_pinfo *inet6 = inet6_sk(sk);
struct ip6_sf_socklist *psl;
- struct net *net = sock_net(sk);
- int i, j, rv;
+ struct inet6_dev *idev;
int leavegroup = 0;
+ int i, j, rv;
int err;
source = &((struct sockaddr_in6 *)&pgsr->gsr_source)->sin6_addr;
@@ -370,13 +372,19 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
if (!ipv6_addr_is_multicast(group))
return -EINVAL;
- idev = ip6_mc_find_dev_rtnl(net, group, pgsr->gsr_interface);
+ idev = ip6_mc_find_dev(net, group, pgsr->gsr_interface);
if (!idev)
return -ENODEV;
+ mutex_lock(&idev->mc_lock);
+
+ if (idev->dead) {
+ err = -ENODEV;
+ goto done;
+ }
+
err = -EADDRNOTAVAIL;
- mutex_lock(&idev->mc_lock);
for_each_pmc_socklock(inet6, sk, pmc) {
if (pgsr->gsr_interface && pmc->ifindex != pgsr->gsr_interface)
continue;
@@ -473,6 +481,7 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
ip6_mc_add_src(idev, group, omode, 1, source, 1);
done:
mutex_unlock(&idev->mc_lock);
+ in6_dev_put(idev);
if (leavegroup)
err = ipv6_sock_mc_drop(sk, pgsr->gsr_interface, group);
return err;
@@ -481,12 +490,12 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf,
struct sockaddr_storage *list)
{
- const struct in6_addr *group;
- struct ipv6_mc_socklist *pmc;
- struct inet6_dev *idev;
struct ipv6_pinfo *inet6 = inet6_sk(sk);
struct ip6_sf_socklist *newpsl, *psl;
struct net *net = sock_net(sk);
+ const struct in6_addr *group;
+ struct ipv6_mc_socklist *pmc;
+ struct inet6_dev *idev;
int leavegroup = 0;
int i, err;
@@ -498,10 +507,17 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf,
gsf->gf_fmode != MCAST_EXCLUDE)
return -EINVAL;
- idev = ip6_mc_find_dev_rtnl(net, group, gsf->gf_interface);
+ idev = ip6_mc_find_dev(net, group, gsf->gf_interface);
if (!idev)
return -ENODEV;
+ mutex_lock(&idev->mc_lock);
+
+ if (idev->dead) {
+ err = -ENODEV;
+ goto done;
+ }
+
err = 0;
if (gsf->gf_fmode == MCAST_INCLUDE && gsf->gf_numsrc == 0) {
@@ -534,24 +550,19 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf,
psin6 = (struct sockaddr_in6 *)list;
newpsl->sl_addr[i] = psin6->sin6_addr;
}
- mutex_lock(&idev->mc_lock);
+
err = ip6_mc_add_src(idev, group, gsf->gf_fmode,
newpsl->sl_count, newpsl->sl_addr, 0);
if (err) {
- mutex_unlock(&idev->mc_lock);
sock_kfree_s(sk, newpsl, struct_size(newpsl, sl_addr,
newpsl->sl_max));
goto done;
}
- mutex_unlock(&idev->mc_lock);
} else {
newpsl = NULL;
- mutex_lock(&idev->mc_lock);
ip6_mc_add_src(idev, group, gsf->gf_fmode, 0, NULL, 0);
- mutex_unlock(&idev->mc_lock);
}
- mutex_lock(&idev->mc_lock);
psl = sock_dereference(pmc->sflist, sk);
if (psl) {
ip6_mc_del_src(idev, group, pmc->sfmode,
@@ -561,12 +572,14 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf,
} else {
ip6_mc_del_src(idev, group, pmc->sfmode, 0, NULL, 0);
}
+
rcu_assign_pointer(pmc->sflist, newpsl);
- mutex_unlock(&idev->mc_lock);
kfree_rcu(psl, rcu);
pmc->sfmode = gsf->gf_fmode;
err = 0;
done:
+ mutex_unlock(&idev->mc_lock);
+ in6_dev_put(idev);
if (leavegroup)
err = ipv6_sock_mc_drop(sk, gsf->gf_interface, group);
return err;
--
2.49.0
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