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ipv6: mcast: Don't hold RTNL for MCAST_ socket options.

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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@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250702230210.3115355-10-kuni1840@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2025-07-02 16:01:26 -07:00 committed by Jakub Kicinski
parent 1e589db389
commit e6e14d582d
2 changed files with 46 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
net/ipv6/ipv6_sockglue.c
View File

@ -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;

76
net/ipv6/mcast.c
View File

@ -302,31 +302,36 @@ 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);
struct rt6_info *rt;
rcu_read_lock();
rt = rt6_lookup(net, group, NULL, 0, NULL, 0);
if (rt) {
dev = rt->dst.dev;
dev = dst_dev(&rt->dst);
dev_hold(dev);
ip6_rt_put(rt);
}
rcu_read_unlock();
} 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;
}
@ -354,16 +359,16 @@ 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 in6_addr *source, *group;
struct ipv6_mc_socklist *pmc;
struct inet6_dev *idev;
struct ipv6_pinfo *inet6 = inet6_sk(sk);
struct ip6_sf_socklist *psl;
struct in6_addr *source, *group;
struct net *net = sock_net(sk);
int i, j, rv;
struct ipv6_mc_socklist *pmc;
struct ip6_sf_socklist *psl;
struct inet6_dev *idev;
int leavegroup = 0;
int i, j, rv;
int err;
source = &((struct sockaddr_in6 *)&pgsr->gsr_source)->sin6_addr;
@ -372,13 +377,19 @@ 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;
@ -475,6 +486,7 @@ 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;
@ -483,12 +495,12 @@ 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;
@ -500,10 +512,17 @@ 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) {
@ -536,24 +555,19 @@ 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,
@ -563,12 +577,14 @@ 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;