Re: [PATCH 4.9 27/75] net: igmp: Use correct source address on IGMPv3 reports

Sebastian Gottschall
2018-01-16T03:50:53Z

please revert that on 4.9 and 4.14
it breaks igmp routing. it can be reproduced with any iptv connection
using igmp-proxy. reverting this patch fixes the issue.

Sebastian

Am 01.01.2018 um 15:32 schrieb Greg Kroah-Hartman:
> 4.9-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Kevin Cernekee <cernekee@chromium.org>
>
>
> [ Upstream commit a46182b00290839fa3fa159d54fd3237bd8669f0 ]
>
> Closing a multicast socket after the final IPv4 address is deleted
> from an interface can generate a membership report that uses the
> source IP from a different interface. The following test script, run
> from an isolated netns, reproduces the issue:
>
> #!/bin/bash
>
> ip link add dummy0 type dummy
> ip link add dummy1 type dummy
> ip link set dummy0 up
> ip link set dummy1 up
> ip addr add 10.1.1.1/24 dev dummy0
> ip addr add 192.168.99.99/24 dev dummy1
>
> tcpdump -U -i dummy0 &
> socat EXEC:"sleep 2" \
> UDP4-DATAGRAM:239.101.1.68:8889,ip-add-membership=239.0.1.68:10.1.1.1 &
>
> sleep 1
> ip addr del 10.1.1.1/24 dev dummy0
> sleep 5
> kill %tcpdump
>
> RFC 3376 specifies that the report must be sent with a valid IP source
> address from the destination subnet, or from address 0.0.0.0. Add an
> extra check to make sure this is the case.
>
> Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> Signed-off-by: David S. Miller <davem@davemloft.net>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> net/ipv4/igmp.c | 20 +++++++++++++++++++-
> 1 file changed, 19 insertions(+), 1 deletion(-)
>
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -89,6 +89,7 @@
> #include <linux/rtnetlink.h>
> #include <linux/times.h>
> #include <linux/pkt_sched.h>
> +#include <linux/byteorder/generic.h>
>
> #include <net/net_namespace.h>
> #include <net/arp.h>
> @@ -321,6 +322,23 @@ igmp_scount(struct ip_mc_list *pmc, int
> return scount;
> }
>
> +/* source address selection per RFC 3376 section 4.2.13 */
> +static __be32 igmpv3_get_srcaddr(struct net_device *dev,
> + const struct flowi4 *fl4)
> +{
> + struct in_device *in_dev = __in_dev_get_rcu(dev);
> +
> + if (!in_dev)
> + return htonl(INADDR_ANY);
> +
> + for_ifa(in_dev) {
> + if (inet_ifa_match(fl4->saddr, ifa))
> + return fl4->saddr;
> + } endfor_ifa(in_dev);
> +
> + return htonl(INADDR_ANY);
> +}
> +
> static struct sk_buff *igmpv3_newpack(struct net_device *dev, unsigned int mtu)
> {
> struct sk_buff *skb;
> @@ -368,7 +386,7 @@ static struct sk_buff *igmpv3_newpack(st
> pip->frag_off = htons(IP_DF);
> pip->ttl = 1;
> pip->daddr = fl4.daddr;
> - pip->saddr = fl4.saddr;
> + pip->saddr = igmpv3_get_srcaddr(dev, &fl4);
> pip->protocol = IPPROTO_IGMP;
> pip->tot_len = 0; /* filled in later */
> ip_select_ident(net, skb, NULL);
>
>
>

--
Mit freundlichen Grüssen / Regards

Sebastian Gottschall / CTO

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