[IPV6]: multicast join and misc
Here is a simplified version of the patch to fix a bug in IPv6
multicasting. It:
1) adds existence check & EADDRINUSE error for regular joins
2) adds an exception for EADDRINUSE in the source-specific multicast
join (where a prior join is ok)
3) adds a missing/needed read_lock on sock_mc_list; would've raced
with destroying the socket on interface down without
4) adds a "leave group" in the (INCLUDE, empty) source filter case.
This frees unneeded socket buffer memory, but also prevents
an inappropriate interaction among the 8 socket options that
mess with this. Some would fail as if in the group when you
aren't really.
Item #4 had a locking bug in the last version of this patch; rather than
removing the idev->lock read lock only, I've simplified it to remove
all lock state in the path and treat it as a direct "leave group" call for
the (INCLUDE,empty) case it covers. Tested on an MP machine. :-)
Much thanks to HoerdtMickael <hoerdt@clarinet.u-strasbg.fr> who
reported the original bug.
Signed-off-by: David L Stevens <dlstevens@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 393b6e6..c0ca92e 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -188,6 +188,16 @@
if (!ipv6_addr_is_multicast(addr))
return -EINVAL;
+ read_lock_bh(&ipv6_sk_mc_lock);
+ for (mc_lst=np->ipv6_mc_list; mc_lst; mc_lst=mc_lst->next) {
+ if ((ifindex == 0 || mc_lst->ifindex == ifindex) &&
+ ipv6_addr_equal(&mc_lst->addr, addr)) {
+ read_unlock_bh(&ipv6_sk_mc_lock);
+ return -EADDRINUSE;
+ }
+ }
+ read_unlock_bh(&ipv6_sk_mc_lock);
+
mc_lst = sock_kmalloc(sk, sizeof(struct ipv6_mc_socklist), GFP_KERNEL);
if (mc_lst == NULL)
@@ -349,6 +359,7 @@
struct ipv6_pinfo *inet6 = inet6_sk(sk);
struct ip6_sf_socklist *psl;
int i, j, rv;
+ int leavegroup = 0;
int err;
if (pgsr->gsr_group.ss_family != AF_INET6 ||
@@ -368,6 +379,7 @@
err = -EADDRNOTAVAIL;
+ read_lock_bh(&ipv6_sk_mc_lock);
for (pmc=inet6->ipv6_mc_list; pmc; pmc=pmc->next) {
if (pgsr->gsr_interface && pmc->ifindex != pgsr->gsr_interface)
continue;
@@ -401,6 +413,12 @@
if (rv) /* source not found */
goto done;
+ /* special case - (INCLUDE, empty) == LEAVE_GROUP */
+ if (psl->sl_count == 1 && omode == MCAST_INCLUDE) {
+ leavegroup = 1;
+ goto done;
+ }
+
/* update the interface filter */
ip6_mc_del_src(idev, group, omode, 1, source, 1);
@@ -453,9 +471,12 @@
/* update the interface list */
ip6_mc_add_src(idev, group, omode, 1, source, 1);
done:
+ read_unlock_bh(&ipv6_sk_mc_lock);
read_unlock_bh(&idev->lock);
in6_dev_put(idev);
dev_put(dev);
+ if (leavegroup)
+ return ipv6_sock_mc_drop(sk, pgsr->gsr_interface, group);
return err;
}