netdev - Re: [PATCH net] net/ipv6: Reinstate ping/traceroute use with source address in VRF

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Date:   Mon, 20 May 2019 19:59:44 +0100
From:   Mike Manning <mmanning@...tta.att-mail.com>
To:     David Ahern <dsahern@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net] net/ipv6: Reinstate ping/traceroute use with source
 address in VRF

On 20/05/2019 17:58, David Ahern wrote:
> On 5/20/19 2:40 AM, Mike Manning wrote:
>> Since the commit 1893ff20275b ("net/ipv6: Add l3mdev check to
>> ipv6_chk_addr_and_flags"), traceroute using TCP SYN or ICMP ECHO option
>> and ping fail when specifying a source address typically on a loopback
>> /dummy interface in the same VRF, e.g.:
>>
>>     # ip vrf exec vrfgreen ping 3000::1 -I 2222::2
>>     ping: bind icmp socket: Cannot assign requested address
>>     # ip vrf exec vrfgreen traceroute 3000::1 -s 2222::2 -T
>>     bind: Cannot assign requested address
>>
>> IPv6 traceroute using default UDP and IPv4 ping & traceroute continue
>> to work inside a VRF using a source address.
>>
>> The reason is that the source address is provided via bind without a
>> device given by these applications in this case. The call to
>> ipv6_check_addr() in rawv6_bind() returns false as the default VRF is
>> assumed if no dev was given, but the src addr is in a non-default VRF.
>>
>> The solution is to check that the address exists in the L3 domain that
>> the dev is part of only if the dev has been specified.
>>
>> Signed-off-by: Mike Manning <mmanning@...tta.att-mail.com>
>> ---
>>  net/ipv6/addrconf.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
>> index f96d1de79509..3963306ec27f 100644
>> --- a/net/ipv6/addrconf.c
>> +++ b/net/ipv6/addrconf.c
>> @@ -1908,6 +1908,7 @@ int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
>>  			    int strict, u32 banned_flags)
>>  {
>>  	unsigned int hash = inet6_addr_hash(net, addr);
>> +	const struct net_device *orig_dev = dev;
>>  	const struct net_device *l3mdev;
>>  	struct inet6_ifaddr *ifp;
>>  	u32 ifp_flags;
>> @@ -1922,7 +1923,7 @@ int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
>>  		if (!net_eq(dev_net(ifp->idev->dev), net))
>>  			continue;
>>  
>> -		if (l3mdev_master_dev_rcu(ifp->idev->dev) != l3mdev)
>> +		if (orig_dev && l3mdev_master_dev_rcu(ifp->idev->dev) != l3mdev)
>>  			continue;
>>  
>>  		/* Decouple optimistic from tentative for evaluation here.
>>
> Wrong fix. When looking up the address you have to give the L3 domain of
> interest.
>
> This change:
>
> diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
> index 84dbe21b71e5..96a3559f2a09 100644
> --- a/net/ipv6/raw.c
> +++ b/net/ipv6/raw.c
> @@ -287,7 +287,9 @@ static int rawv6_bind(struct sock *sk, struct
> sockaddr *uaddr, int addr_len)
>                         /* Binding to link-local address requires an
> interface */
>                         if (!sk->sk_bound_dev_if)
>                                 goto out_unlock;
> +               }
>
> +               if (sk->sk_bound_dev_if) {
>                         err = -ENODEV;
>                         dev = dev_get_by_index_rcu(sock_net(sk),
>                                                    sk->sk_bound_dev_if);
>
> make raw binds similar to tcp. See:
>
> c5ee066333ebc ("ipv6: Consider sk_bound_dev_if when binding a socket to
> an address")
> ec90ad334986f ("ipv6: Consider sk_bound_dev_if when binding a socket to
> a v4 mapped address")

Thanks, I withdraw this submission and have submitted a new one as you
recommend.