On 10/31/17 7:32 AM, Paolo Abeni wrote:
> David reported breakages of VRF scenarios due to the
> commit 6e617de84e87 ("net: avoid a full fib lookup when rp_filter is
> disabled."): the local addresses based test is too strict when VRFs
> are in place.
>
> With this change we fall-back to a full lookup when custom fib rules
> are in place; so that we address the VRF use case and possibly other
> similar issues in non trivial setups.
>
> v1 -> v2:
> - fix build breakage when CONFIG_IP_MULTIPLE_TABLES is not defined,
> reported by the kbuild test robot
>
> Reported-by: David Ahern <dsah...@gmail.com>
> Fixes: 6e617de84e87 ("net: avoid a full fib lookup when rp_filter is
> disabled.")
> Signed-off-by: Paolo Abeni <pab...@redhat.com>
> ---
> net/ipv4/fib_frontend.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
> index f02819134ba2..f52d27a422c3 100644
> --- a/net/ipv4/fib_frontend.c
> +++ b/net/ipv4/fib_frontend.c
> @@ -73,6 +73,11 @@ static int __net_init fib4_rules_init(struct net *net)
> fib_free_table(main_table);
> return -ENOMEM;
> }
> +
> +static bool fib4_has_custom_rules(struct net *net)
> +{
> + return false;
> +}
> #else
>
> struct fib_table *fib_new_table(struct net *net, u32 id)
> @@ -128,6 +133,11 @@ struct fib_table *fib_get_table(struct net *net, u32 id)
> }
> return NULL;
> }
> +
> +static bool fib4_has_custom_rules(struct net *net)
> +{
> + return net->ipv4.fib_has_custom_rules;
> +}
> #endif /* CONFIG_IP_MULTIPLE_TABLES */
>
> static void fib_replace_table(struct net *net, struct fib_table *old,
> @@ -405,10 +415,12 @@ int fib_validate_source(struct sk_buff *skb, __be32
> src, __be32 dst,
> (dev->ifindex != oif || !IN_DEV_TX_REDIRECTS(idev))) {
> if (IN_DEV_ACCEPT_LOCAL(idev))
> goto ok;
> - /* if no local routes are added from user space we can check
> - * for local addresses looking-up the ifaddr table
> + /* with custom local routes in place, checking local addresses
> + * only will be too optimistic, with custom rules, checking
> + * local addresses only can be too strict, e.g. due to vrf
> */
> - if (net->ipv4.fib_has_custom_local_routes)
> + if (net->ipv4.fib_has_custom_local_routes ||
> + fib4_has_custom_rules(net))
> goto full_check;
> if (inet_lookup_ifaddr_rcu(net, src))
> return -EINVAL;
>
That seems specific to VRF, but I can't think of a better solution. so,
Acked-by: David Ahern <dsah...@gmail.com>
