On Tue, Jun 06, 2023 at 08:24:54AM +0200, Mirsad Goran Todorovac wrote:
> On 5/31/23 20:11, Guillaume Nault wrote:
> > I believe this condition should be relaxed to allow the case where
> > ->sk_bound_dev_if is oif's master device (and maybe there are other
> > VRF cases to also consider).
>
> I've tried something like this, but something makes the kernel stuck
> here:
>
> TEST: ping out, blocked by route - ns-B loopback IPv6 [ OK ]
> TEST: ping out, device bind, blocked by route - ns-B loopback IPv6 [ OK ]
> TEST: ping in, blocked by route - ns-A loopback IPv6 [ OK ]
> TEST: ping out, unreachable route - ns-B loopback IPv6 [ OK ]
> TEST: ping out, device bind, unreachable route - ns-B loopback IPv6 [ OK ]
>
> #################################################################
> With VRF
>
> [hanged process and kernel won't shutdown]
>
> The code is:
>
> ---
> net/ipv6/ping.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
> index c4835dbdfcff..81293e902293 100644
> --- a/net/ipv6/ping.c
> +++ b/net/ipv6/ping.c
> @@ -73,6 +73,9 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> struct rt6_info *rt;
> struct pingfakehdr pfh;
> struct ipcm6_cookie ipc6;
> + struct net *net = sock_net(sk);
> + struct net_device *dev = NULL;
> + struct net_device *mdev = NULL;
> err = ping_common_sendmsg(AF_INET6, msg, len, &user_icmph,
> sizeof(user_icmph));
> @@ -111,10 +114,17 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> else if (!oif)
> oif = np->ucast_oif;
> + if (oif) {
> + dev = dev_get_by_index(net, oif);
> + mdev = netdev_master_upper_dev_get(dev);
> + }
> +
> addr_type = ipv6_addr_type(daddr);
> if ((__ipv6_addr_needs_scope_id(addr_type) && !oif) ||
> (addr_type & IPV6_ADDR_MAPPED) ||
> - (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if))
> + (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if &&
> + !(mdev && sk->sk_bound_dev_if &&
> + mdev != dev_get_by_index(net, sk->sk_bound_dev_if))))
> return -EINVAL;
> ipcm6_init_sk(&ipc6, np);
>
> I am obviously doing something very stupid.
The problem is that dev_get_by_index() holds a reference on 'dev' which
your code never releases. Also netdev_master_upper_dev_get() needs rtnl
protection. These should have generated some kernel oops.
You can try this instead:
-------- >8 --------
diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index c4835dbdfcff..f804c11e2146 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -114,7 +114,8 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
addr_type = ipv6_addr_type(daddr);
if ((__ipv6_addr_needs_scope_id(addr_type) && !oif) ||
(addr_type & IPV6_ADDR_MAPPED) ||
- (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if))
+ (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if &&
+ l3mdev_master_ifindex_by_index(sock_net(sk), oif) != sk->sk_bound_dev_if))
return -EINVAL;
ipcm6_init_sk(&ipc6, np);
