[PATCH net 0/2] l3mdev: Fix ip tunnel case after recent l3mdev change

[PATCH net 0/2] l3mdev: Fix ip tunnel case after recent l3mdev change

[David Ahern]

Second patch provides a fix for ip tunnels after the recent l3mdev change
that avoids touching the oif in the flow struct. First patch preemptively
provides a fix to an existing function that the second patch uses.

David Ahern (2):
  l3mdev: l3mdev_master_upper_ifindex_by_index_rcu should be using
    netdev_master_upper_dev_get_rcu
  net: Handle l3mdev in ip_tunnel_init_flow

 drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c |  2 +-
 include/net/ip_tunnels.h                            | 11 +++++++++--
 net/ipv4/ip_gre.c                                   |  4 ++--
 net/ipv4/ip_tunnel.c                                |  9 +++++----
 net/l3mdev/l3mdev.c                                 |  2 +-
 5 files changed, 18 insertions(+), 10 deletions(-)

-- 
2.24.3 (Apple Git-128)

[PATCH net 1/2] l3mdev: l3mdev_master_upper_ifindex_by_index_rcu should be using netdev_master_upper_dev_get_rcu

[David Ahern]

Next patch uses l3mdev_master_upper_ifindex_by_index_rcu which throws
a splat with debug kernels:

[13783.087570] ------------[ cut here ]------------
[13783.093974] RTNL: assertion failed at net/core/dev.c (6702)
[13783.100761] WARNING: CPU: 3 PID: 51132 at net/core/dev.c:6702 netdev_master_upper_dev_get+0x16a/0x1a0

[13783.184226] CPU: 3 PID: 51132 Comm: kworker/3:3 Not tainted 5.17.0-custom-100090-g6f963aafb1cc #682
[13783.194788] Hardware name: Mellanox Technologies Ltd. MSN2010/SA002610, BIOS 5.6.5 08/24/2017
[13783.204755] Workqueue: mld mld_ifc_work [ipv6]
[13783.210338] RIP: 0010:netdev_master_upper_dev_get+0x16a/0x1a0
[13783.217209] Code: 0f 85 e3 fe ff ff e8 65 ac ec fe ba 2e 1a 00 00 48 c7 c6 60 6f 38 83 48 c7 c7 c0 70 38 83 c6 05 5e b5 d7 01 01 e8 c6 29 52 00 <0f> 0b e9 b8 fe ff ff e8 5a 6c 35 ff e9 1c ff ff ff 48 89 ef e8 7d
[13783.238659] RSP: 0018:ffffc9000b37f5a8 EFLAGS: 00010286
[13783.244995] RAX: 0000000000000000 RBX: ffff88812ee5c000 RCX: 0000000000000000
[13783.253379] RDX: ffff88811ce09d40 RSI: ffffffff812d0fcd RDI: fffff5200166fea7
[13783.261769] RBP: 0000000000000000 R08: 0000000000000001 R09: ffff8882375f4287
[13783.270138] R10: ffffed1046ebe850 R11: 0000000000000001 R12: dffffc0000000000
[13783.278510] R13: 0000000000000275 R14: ffffc9000b37f688 R15: ffff8881273b4af8
[13783.286870] FS:  0000000000000000(0000) GS:ffff888237400000(0000) knlGS:0000000000000000
[13783.296352] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[13783.303177] CR2: 00007ff25fc9b2e8 CR3: 0000000174d23000 CR4: 00000000001006e0
[13783.311546] Call Trace:
[13783.314660]  <TASK>
[13783.317553]  l3mdev_master_upper_ifindex_by_index_rcu+0x43/0xe0
...

Change l3mdev_master_upper_ifindex_by_index_rcu to use
netdev_master_upper_dev_get_rcu.

Fixes: 6a6d6681ac1a ("l3mdev: add function to retreive upper master")
Signed-off-by: Ido Schimmel <idosch@idosch.org>
Signed-off-by: David Ahern <dsahern@kernel.org>
Cc: Alexis Bauvin <abauvin@scaleway.com>
---
 net/l3mdev/l3mdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/l3mdev/l3mdev.c b/net/l3mdev/l3mdev.c
index 4eb8892fb2ff..ca10916340b0 100644
--- a/net/l3mdev/l3mdev.c
+++ b/net/l3mdev/l3mdev.c
@@ -147,7 +147,7 @@ int l3mdev_master_upper_ifindex_by_index_rcu(struct net *net, int ifindex)
 
 	dev = dev_get_by_index_rcu(net, ifindex);
 	while (dev && !netif_is_l3_master(dev))
-		dev = netdev_master_upper_dev_get(dev);
+		dev = netdev_master_upper_dev_get_rcu(dev);
 
 	return dev ? dev->ifindex : 0;
 }
-- 
2.24.3 (Apple Git-128)

[PATCH net 2/2] net: Handle l3mdev in ip_tunnel_init_flow

[David Ahern]

Ido reported that the commit referenced in the Fixes tag broke
a gre use case with dummy devices. Add a check to ip_tunnel_init_flow
to see if the oif is an l3mdev port and if so set the oif to 0 to
avoid the oif comparison in fib_lookup_good_nhc.

Fixes: 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif reset for port devices")
Reported-by: Ido Schimmel <idosch@idosch.org>
Signed-off-by: David Ahern <dsahern@kernel.org>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c |  2 +-
 include/net/ip_tunnels.h                            | 11 +++++++++--
 net/ipv4/ip_gre.c                                   |  4 ++--
 net/ipv4/ip_tunnel.c                                |  9 +++++----
 4 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
index b73466470f75..fe663b0ab708 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
@@ -423,7 +423,7 @@ mlxsw_sp_span_gretap4_route(const struct net_device *to_dev,
 
 	parms = mlxsw_sp_ipip_netdev_parms4(to_dev);
 	ip_tunnel_init_flow(&fl4, parms.iph.protocol, *daddrp, *saddrp,
-			    0, 0, parms.link, tun->fwmark, 0);
+			    0, 0, dev_net(to_dev), parms.link, tun->fwmark, 0);
 
 	rt = ip_route_output_key(tun->net, &fl4);
 	if (IS_ERR(rt))
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index 0219fe907b26..88dee57eac8a 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -243,11 +243,18 @@ static inline __be32 tunnel_id_to_key32(__be64 tun_id)
 static inline void ip_tunnel_init_flow(struct flowi4 *fl4,
 				       int proto,
 				       __be32 daddr, __be32 saddr,
-				       __be32 key, __u8 tos, int oif,
+				       __be32 key, __u8 tos,
+				       struct net *net, int oif,
 				       __u32 mark, __u32 tun_inner_hash)
 {
 	memset(fl4, 0, sizeof(*fl4));
-	fl4->flowi4_oif = oif;
+
+	if (oif) {
+		fl4->flowi4_l3mdev = l3mdev_master_upper_ifindex_by_index_rcu(net, oif);
+		/* Legacy VRF/l3mdev use case */
+		fl4->flowi4_oif = fl4->flowi4_l3mdev ? 0 : oif;
+	}
+
 	fl4->daddr = daddr;
 	fl4->saddr = saddr;
 	fl4->flowi4_tos = tos;
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 99db2e41ed10..365caebf51ab 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -605,8 +605,8 @@ static int gre_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
 	key = &info->key;
 	ip_tunnel_init_flow(&fl4, IPPROTO_GRE, key->u.ipv4.dst, key->u.ipv4.src,
 			    tunnel_id_to_key32(key->tun_id),
-			    key->tos & ~INET_ECN_MASK, 0, skb->mark,
-			    skb_get_hash(skb));
+			    key->tos & ~INET_ECN_MASK, dev_net(dev), 0,
+			    skb->mark, skb_get_hash(skb));
 	rt = ip_route_output_key(dev_net(dev), &fl4);
 	if (IS_ERR(rt))
 		return PTR_ERR(rt);
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 5a473319d3a5..94017a8c3994 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -294,8 +294,8 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
 
 		ip_tunnel_init_flow(&fl4, iph->protocol, iph->daddr,
 				    iph->saddr, tunnel->parms.o_key,
-				    RT_TOS(iph->tos), tunnel->parms.link,
-				    tunnel->fwmark, 0);
+				    RT_TOS(iph->tos), dev_net(dev),
+				    tunnel->parms.link, tunnel->fwmark, 0);
 		rt = ip_route_output_key(tunnel->net, &fl4);
 
 		if (!IS_ERR(rt)) {
@@ -570,7 +570,7 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 	}
 	ip_tunnel_init_flow(&fl4, proto, key->u.ipv4.dst, key->u.ipv4.src,
 			    tunnel_id_to_key32(key->tun_id), RT_TOS(tos),
-			    0, skb->mark, skb_get_hash(skb));
+			    dev_net(dev), 0, skb->mark, skb_get_hash(skb));
 	if (tunnel->encap.type != TUNNEL_ENCAP_NONE)
 		goto tx_error;
 
@@ -726,7 +726,8 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 	}
 
 	ip_tunnel_init_flow(&fl4, protocol, dst, tnl_params->saddr,
-			    tunnel->parms.o_key, RT_TOS(tos), tunnel->parms.link,
+			    tunnel->parms.o_key, RT_TOS(tos),
+			    dev_net(dev), tunnel->parms.link,
 			    tunnel->fwmark, skb_get_hash(skb));
 
 	if (ip_tunnel_encap(skb, tunnel, &protocol, &fl4) < 0)
-- 
2.24.3 (Apple Git-128)

Re: [PATCH net 0/2] l3mdev: Fix ip tunnel case after recent l3mdev change

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 13 Apr 2022 11:43:18 -0600 you wrote:
> Second patch provides a fix for ip tunnels after the recent l3mdev change
> that avoids touching the oif in the flow struct. First patch preemptively
> provides a fix to an existing function that the second patch uses.
> 
> David Ahern (2):
>   l3mdev: l3mdev_master_upper_ifindex_by_index_rcu should be using
>     netdev_master_upper_dev_get_rcu
>   net: Handle l3mdev in ip_tunnel_init_flow
> 
> [...]

Here is the summary with links:
  - [net,1/2] l3mdev: l3mdev_master_upper_ifindex_by_index_rcu should be using netdev_master_upper_dev_get_rcu
    https://git.kernel.org/netdev/net/c/83daab06252e
  - [net,2/2] net: Handle l3mdev in ip_tunnel_init_flow
    https://git.kernel.org/netdev/net/c/db53cd3d88dc

You are awesome, thank you!
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