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

Sebastian Gottschall
2018-01-16T04:55:36Z

3.18 and 4.4 is affected too

Am 16.01.2018 um 04:50 schrieb Sebastian Gottschall:
> 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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