Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935237AbcKMUph (ORCPT ); Sun, 13 Nov 2016 15:45:37 -0500 Received: from mail-it0-f44.google.com ([209.85.214.44]:38304 "EHLO mail-it0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933451AbcKMUpf (ORCPT ); Sun, 13 Nov 2016 15:45:35 -0500 Subject: Re: [PATCH v2] ip6_output: ensure flow saddr actually belongs to device To: "Jason A. Donenfeld" , Netdev , WireGuard mailing list , LKML , YOSHIFUJI Hideaki , Hannes Frederic Sowa References: <405b2e79-854d-4c30-07b0-bd524137d2f6@cumulusnetworks.com> <20161113190251.1027-1-Jason@zx2c4.com> From: David Ahern Message-ID: <27cccef1-06d9-74b3-5b8a-912850119a76@cumulusnetworks.com> Date: Sun, 13 Nov 2016 13:45:31 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20161113190251.1027-1-Jason@zx2c4.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3393 Lines: 88 On 11/13/16 12:02 PM, Jason A. Donenfeld wrote: > This puts the IPv6 routing functions in parity with the IPv4 routing > functions. Namely, we now check in v6 that if a flowi6 requests an > saddr, the returned dst actually corresponds to a net device that has > that saddr. This mirrors the v4 logic with __ip_dev_find in > __ip_route_output_key_hash. In the event that the returned dst is not > for a dst with a dev that has the saddr, we return -EINVAL, just like > v4; this makes it easy to use the same error handlers for both cases. > > Signed-off-by: Jason A. Donenfeld > Cc: David Ahern > --- > Changes from v1: > This moves the check to the top and now sees if it's a valid address > on _any_ device, not just the one in dst. > > include/net/ipv6.h | 2 ++ > net/ipv6/ip6_output.c | 28 ++++++++++++++++++++++++++++ > 2 files changed, 30 insertions(+) > > diff --git a/include/net/ipv6.h b/include/net/ipv6.h > index 8fed1cd..e5dc14f 100644 > --- a/include/net/ipv6.h > +++ b/include/net/ipv6.h > @@ -914,6 +914,8 @@ struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6, > const struct in6_addr *final_dst); > struct dst_entry *ip6_blackhole_route(struct net *net, > struct dst_entry *orig_dst); > +struct net_device *__ip6_dev_find(struct net *net, struct in6_addr *addr, > + bool devref); > > /* > * skb processing functions > diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c > index 6001e78..371170b 100644 > --- a/net/ipv6/ip6_output.c > +++ b/net/ipv6/ip6_output.c > @@ -916,6 +916,30 @@ static struct dst_entry *ip6_sk_dst_check(struct sock *sk, > return dst; > } > > +/** > + * __ip6_dev_find - find the first device with a given source address. > + * @net: the net namespace > + * @addr: the source address > + * @devref: if true, take a reference on the found device > + * > + * If a caller uses devref=false, it should be protected by RCU, or RTNL > + */ > +struct net_device *__ip6_dev_find(struct net *net, struct in6_addr *addr, bool devref) > +{ > + struct net_device *result; > + > + rcu_read_lock(); > + for_each_netdev_rcu(net, result) { > + if (ipv6_chk_addr(net, addr, result, 1)) > + break; > + } > + if (result && devref) > + dev_hold(result); > + rcu_read_unlock(); > + return result; > +} > +EXPORT_SYMBOL(__ip6_dev_find); You don't need a new function to walk all interfaces; just use ipv6_chk_addr with a dev arg of NULL. IPv6 has a hash table with all unicast addresses -- inet6_addr_lst. ipv6_chk_addr is checking that list for the address in question. The actual device is not relevant for verifying the address is a valid local one (though the device can be returned from ifp->idev->dev if ever needed). So drop the above ... > + > static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk, > struct dst_entry **dst, struct flowi6 *fl6) > { > @@ -926,6 +950,10 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk, > int err; > int flags = 0; > > + if (!ipv6_addr_any(&fl6->saddr) && > + !__ip6_dev_find(net, &fl6->saddr, false)) ... and just use ipv6_chk_addr here. > + return -EINVAL; > + > /* The correct way to handle this would be to do > * ip6_route_get_saddr, and then ip6_route_output; however, > * the route-specific preferred source forces the >