Based on RFC3376 5.1
If no interface
state existed for that multicast address before the change (i.e., the
change consisted of creating a new per-interface record), or if no
state exists after the change (i.e., the change consisted of deleting
a per-interface record), then the "non-existent" state is considered
to have a filter mode of INCLUDE and an empty source list.
Which means a new multicast group should start with state IN().
Function ip_mc_join_group() works correctly for IGMP ASM(Any-Source Multicast)
mode. It adds a group with state EX() and inits crcount to mc_qrv,
so the kernel will send a TO_EX() report message after adding group.
But for IGMPv3 SSM(Source-specific multicast) JOIN_SOURCE_GROUP mode, we
split the group joining into two steps. First we join the group like ASM,
i.e. via ip_mc_join_group(). So the state changes from IN() to EX().
Then we add the source-specific address with INCLUDE mode. So the state
changes from EX() to IN(A).
Before the first step sends a group change record, we finished the second
step. So we will only send the second change record. i.e. TO_IN(A).
Regarding the RFC stands, we should actually send an ALLOW(A) message for
SSM JOIN_SOURCE_GROUP as the state should mimic the 'IN() to IN(A)'
transition.
The issue was exposed by commit a052517a8ff65 ("net/multicast: should not
send source list records when have filter mode change"). Before this change,
we used to send both ALLOW(A) and TO_IN(A). After this change we only send
TO_IN(A).
Fix it by adding a new parameter to init group mode. Also add new wrapper
functions so we don't need to change too much code.
v1 -> v2:
In my first version I only cleared the group change record. But this is not
enough. Because when a new group join, it will init as EXCLUDE and trigger
an filter mode change in ip/ip6_mc_add_src(), which will clear all source
addresses' sf_crcount. This will prevent early joined address sending state
change records if multi source addressed joined at the same time.
In v2 patch, I fixed it by directly initializing the mode to INCLUDE for SSM
JOIN_SOURCE_GROUP. I also split the original patch into two separated patches
for IPv4 and IPv6.
Fixes: a052517a8ff65 ("net/multicast: should not send source list records when
have filter mode change")
Reviewed-by: Stefano Brivio <sbri...@redhat.com>
Signed-off-by: Hangbin Liu <liuhang...@gmail.com>
---
include/linux/igmp.h | 2 ++
net/ipv4/igmp.c | 58 ++++++++++++++++++++++++++++++++++++--------------
net/ipv4/ip_sockglue.c | 4 ++--
3 files changed, 46 insertions(+), 18 deletions(-)
diff --git a/include/linux/igmp.h b/include/linux/igmp.h
index f823185..119f539 100644
--- a/include/linux/igmp.h
+++ b/include/linux/igmp.h
@@ -109,6 +109,8 @@ struct ip_mc_list {
extern int ip_check_mc_rcu(struct in_device *dev, __be32 mc_addr, __be32
src_addr, u8 proto);
extern int igmp_rcv(struct sk_buff *);
extern int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr);
+extern int ip_mc_join_group_ssm(struct sock *sk, struct ip_mreqn *imr,
+ unsigned int mode);
extern int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr);
extern void ip_mc_drop_socket(struct sock *sk);
extern int ip_mc_source(int add, int omode, struct sock *sk,
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index b26a81a..ef72499 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1200,13 +1200,14 @@ static void igmpv3_del_delrec(struct in_device *in_dev,
struct ip_mc_list *im)
spin_lock_bh(&im->lock);
if (pmc) {
im->interface = pmc->interface;
- im->crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
im->sfmode = pmc->sfmode;
if (pmc->sfmode == MCAST_INCLUDE) {
im->tomb = pmc->tomb;
im->sources = pmc->sources;
for (psf = im->sources; psf; psf = psf->sf_next)
- psf->sf_crcount = im->crcount;
+ psf->sf_crcount = in_dev->mr_qrv ?:
net->ipv4.sysctl_igmp_qrv;
+ } else {
+ im->crcount = in_dev->mr_qrv ?:
net->ipv4.sysctl_igmp_qrv;
}
in_dev_put(pmc->interface);
kfree(pmc);
@@ -1288,7 +1289,7 @@ static void igmp_group_dropped(struct ip_mc_list *im)
#endif
}
-static void igmp_group_added(struct ip_mc_list *im)
+static void igmp_group_added(struct ip_mc_list *im, unsigned int mode)
{
struct in_device *in_dev = im->interface;
#ifdef CONFIG_IP_MULTICAST
@@ -1316,7 +1317,13 @@ static void igmp_group_added(struct ip_mc_list *im)
}
/* else, v3 */
- im->crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
+ /* Based on RFC3376 5.1, for newly added INCLUDE SSM, we should
+ * not send filter-mode change record as the mode should be from
+ * IN() to IN(A).
+ */
+ if (mode == MCAST_EXCLUDE)
+ im->crcount = in_dev->mr_qrv ?: net->ipv4.sysctl_igmp_qrv;
+
igmp_ifc_event(in_dev);
#endif
}
@@ -1381,8 +1388,7 @@ static void ip_mc_hash_remove(struct in_device *in_dev,
/*
* A socket has joined a multicast group on device dev.
*/
-
-void ip_mc_inc_group(struct in_device *in_dev, __be32 addr)
+void __ip_mc_inc_group(struct in_device *in_dev, __be32 addr, unsigned int
mode)
{
struct ip_mc_list *im;
#ifdef CONFIG_IP_MULTICAST
@@ -1394,7 +1400,7 @@ void ip_mc_inc_group(struct in_device *in_dev, __be32
addr)
for_each_pmc_rtnl(in_dev, im) {
if (im->multiaddr == addr) {
im->users++;
- ip_mc_add_src(in_dev, &addr, MCAST_EXCLUDE, 0, NULL, 0);
+ ip_mc_add_src(in_dev, &addr, mode, 0, NULL, 0);
goto out;
}
}
@@ -1408,8 +1414,8 @@ void ip_mc_inc_group(struct in_device *in_dev, __be32
addr)
in_dev_hold(in_dev);
im->multiaddr = addr;
/* initial mode is (EX, empty) */
- im->sfmode = MCAST_EXCLUDE;
- im->sfcount[MCAST_EXCLUDE] = 1;
+ im->sfmode = mode;
+ im->sfcount[mode] = 1;
refcount_set(&im->refcnt, 1);
spin_lock_init(&im->lock);
#ifdef CONFIG_IP_MULTICAST
@@ -1426,12 +1432,17 @@ void ip_mc_inc_group(struct in_device *in_dev, __be32
addr)
#ifdef CONFIG_IP_MULTICAST
igmpv3_del_delrec(in_dev, im);
#endif
- igmp_group_added(im);
+ igmp_group_added(im, mode);
if (!in_dev->dead)
ip_rt_multicast_event(in_dev);
out:
return;
}
+
+void ip_mc_inc_group(struct in_device *in_dev, __be32 addr)
+{
+ __ip_mc_inc_group(in_dev, addr, MCAST_EXCLUDE);
+}
EXPORT_SYMBOL(ip_mc_inc_group);
static int ip_mc_check_iphdr(struct sk_buff *skb)
@@ -1688,7 +1699,7 @@ void ip_mc_remap(struct in_device *in_dev)
#ifdef CONFIG_IP_MULTICAST
igmpv3_del_delrec(in_dev, pmc);
#endif
- igmp_group_added(pmc);
+ igmp_group_added(pmc, pmc->sfmode);
}
}
@@ -1751,7 +1762,7 @@ void ip_mc_up(struct in_device *in_dev)
#ifdef CONFIG_IP_MULTICAST
igmpv3_del_delrec(in_dev, pmc);
#endif
- igmp_group_added(pmc);
+ igmp_group_added(pmc, pmc->sfmode);
}
}
@@ -2130,8 +2141,8 @@ static void ip_mc_clear_src(struct ip_mc_list *pmc)
/* Join a multicast group
*/
-
-int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr)
+static int __ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr,
+ unsigned int mode)
{
__be32 addr = imr->imr_multiaddr.s_addr;
struct ip_mc_socklist *iml, *i;
@@ -2172,15 +2183,30 @@ int ip_mc_join_group(struct sock *sk, struct ip_mreqn
*imr)
memcpy(&iml->multi, imr, sizeof(*imr));
iml->next_rcu = inet->mc_list;
iml->sflist = NULL;
- iml->sfmode = MCAST_EXCLUDE;
+ iml->sfmode = mode;
rcu_assign_pointer(inet->mc_list, iml);
- ip_mc_inc_group(in_dev, addr);
+ __ip_mc_inc_group(in_dev, addr, mode);
err = 0;
done:
return err;
}
+
+/* Join ASM (Any-Source Multicast) group
+ */
+int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr)
+{
+ return __ip_mc_join_group(sk, imr, MCAST_EXCLUDE);
+}
EXPORT_SYMBOL(ip_mc_join_group);
+/* Join SSM (Source-Specific Multicast) group
+ */
+int ip_mc_join_group_ssm(struct sock *sk, struct ip_mreqn *imr,
+ unsigned int mode)
+{
+ return __ip_mc_join_group(sk, imr, mode);
+}
+
static int ip_mc_leave_src(struct sock *sk, struct ip_mc_socklist *iml,
struct in_device *in_dev)
{
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 57bbb06..5f28607 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -982,7 +982,7 @@ static int do_ip_setsockopt(struct sock *sk, int level,
mreq.imr_multiaddr.s_addr = mreqs.imr_multiaddr;
mreq.imr_address.s_addr = mreqs.imr_interface;
mreq.imr_ifindex = 0;
- err = ip_mc_join_group(sk, &mreq);
+ err = ip_mc_join_group_ssm(sk, &mreq, MCAST_INCLUDE);
if (err && err != -EADDRINUSE)
break;
omode = MCAST_INCLUDE;
@@ -1059,7 +1059,7 @@ static int do_ip_setsockopt(struct sock *sk, int level,
mreq.imr_multiaddr = psin->sin_addr;
mreq.imr_address.s_addr = 0;
mreq.imr_ifindex = greqs.gsr_interface;
- err = ip_mc_join_group(sk, &mreq);
+ err = ip_mc_join_group_ssm(sk, &mreq, MCAST_INCLUDE);
if (err && err != -EADDRINUSE)
break;
greqs.gsr_interface = mreq.imr_ifindex;
--
2.5.5
