[PATCHv5 net-next 0/2] net: enable udp v6 sockets receiving v4 packets with UDP

Currently, udp v6 socket can not process v4 packets with UDP GRO, as
udp_encap_needed_key is not increased when udp_tunnel_encap_enable()
is called for v6 socket.

This patchset is to increase it and remove the unnecessary code in
bareudp in Patch 1/2, and improve rxrpc encap_enable by calling
udp_tunnel_encap_enable().

v1->v4:
  - See patch 1/2.
v4->v5:
  - See patch 2/2.

Xin Long (2):
  udp: call udp_encap_enable for v6 sockets when enabling encap
  rxrpc: call udp_tunnel_encap_enable in rxrpc_open_socket

 drivers/net/bareudp.c    | 6 ------
 include/net/udp.h        | 1 +
 include/net/udp_tunnel.h | 3 +--
 net/ipv4/udp.c           | 6 ++++++
 net/ipv6/udp.c           | 4 +++-
 net/rxrpc/local_object.c | 7 ++-----
 6 files changed, 13 insertions(+), 14 deletions(-)

-- 
2.1.0

When enabling encap for a ipv6 socket without udp_encap_needed_key
increased, UDP GRO won't work for v4 mapped v6 address packets as
sk will be NULL in udp4_gro_receive().

This patch is to enable it by increasing udp_encap_needed_key for
v6 sockets in udp_tunnel_encap_enable(), and correspondingly
decrease udp_encap_needed_key in udpv6_destroy_sock().

v1->v2:
  - add udp_encap_disable() and export it.
v2->v3:
  - add the change for rxrpc and bareudp into one patch, as Alex
    suggested.
v3->v4:
  - move rxrpc part to another patch.

Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 drivers/net/bareudp.c    | 6 ------
 include/net/udp.h        | 1 +
 include/net/udp_tunnel.h | 3 +--
 net/ipv4/udp.c           | 6 ++++++
 net/ipv6/udp.c           | 4 +++-
 5 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c
index 1b8f597..7511bca 100644
--- a/drivers/net/bareudp.c
+++ b/drivers/net/bareudp.c

@@ -240,12 +240,6 @@ static int bareudp_socket_create(struct bareudp_dev *bareudp, __be16 port)
 	tunnel_cfg.encap_destroy = NULL;
 	setup_udp_tunnel_sock(bareudp->net, sock, &tunnel_cfg);
 
-	/* As the setup_udp_tunnel_sock does not call udp_encap_enable if the
-	 * socket type is v6 an explicit call to udp_encap_enable is needed.
-	 */
-	if (sock->sk->sk_family == AF_INET6)
-		udp_encap_enable();
-
 	rcu_assign_pointer(bareudp->sock, sock);
 	return 0;
 }

diff --git a/include/net/udp.h b/include/net/udp.h
index 01351ba..5ddbb42 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h

@@ -467,6 +467,7 @@ void udp_init(void);
 
 DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
 void udp_encap_enable(void);
+void udp_encap_disable(void);
 #if IS_ENABLED(CONFIG_IPV6)
 DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
 void udpv6_encap_enable(void);

diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
index 282d10e..afc7ce7 100644
--- a/include/net/udp_tunnel.h
+++ b/include/net/udp_tunnel.h

@@ -181,9 +181,8 @@ static inline void udp_tunnel_encap_enable(struct socket *sock)
 #if IS_ENABLED(CONFIG_IPV6)
 	if (sock->sk->sk_family == PF_INET6)
 		ipv6_stub->udpv6_encap_enable();
-	else
 #endif
-		udp_encap_enable();
+	udp_encap_enable();
 }
 
 #define UDP_TUNNEL_NIC_MAX_TABLES	4

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 69ea765..48208fb 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c

@@ -596,6 +596,12 @@ void udp_encap_enable(void)
 }
 EXPORT_SYMBOL(udp_encap_enable);
 
+void udp_encap_disable(void)
+{
+	static_branch_dec(&udp_encap_needed_key);
+}
+EXPORT_SYMBOL(udp_encap_disable);
+
 /* Handler for tunnels with arbitrary destination ports: no socket lookup, go
  * through error handlers in encapsulations looking for a match.
  */

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index b9f3dfd..d754292 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c

@@ -1608,8 +1608,10 @@ void udpv6_destroy_sock(struct sock *sk)
 			if (encap_destroy)
 				encap_destroy(sk);
 		}
-		if (up->encap_enabled)
+		if (up->encap_enabled) {
 			static_branch_dec(&udpv6_encap_needed_key);
+			udp_encap_disable();
+		}
 	}
 
 	inet6_destroy_sock(sk);

-- 
2.1.0

When doing encap_enable/increasing encap_needed_key, up->encap_enabled
is not set in rxrpc_open_socket(), and it will cause encap_needed_key
not being decreased in udpv6_destroy_sock().

This patch is to improve it by just calling udp_tunnel_encap_enable()
where it increases both UDP and UDPv6 encap_needed_key and sets
up->encap_enabled.

v4->v5:
  - add the missing '#include <net/udp_tunnel.h>', as David Howells
    noticed.

Acked-and-tested-by: David Howells [off-list ref]
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/rxrpc/local_object.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index 8c28810..33b4936 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c

@@ -16,6 +16,7 @@
 #include <linux/hashtable.h>
 #include <net/sock.h>
 #include <net/udp.h>
+#include <net/udp_tunnel.h>
 #include <net/af_rxrpc.h>
 #include "ar-internal.h"
 

@@ -135,11 +136,7 @@ static int rxrpc_open_socket(struct rxrpc_local *local, struct net *net)
 	udp_sk(usk)->gro_receive = NULL;
 	udp_sk(usk)->gro_complete = NULL;
 
-	udp_encap_enable();
-#if IS_ENABLED(CONFIG_AF_RXRPC_IPV6)
-	if (local->srx.transport.family == AF_INET6)
-		udpv6_encap_enable();
-#endif
+	udp_tunnel_encap_enable(local->socket);
 	usk->sk_error_report = rxrpc_error_report;
 
 	/* if a local address was supplied then bind it */

-- 
2.1.0

Xin Long [off-list ref] wrote:

When doing encap_enable/increasing encap_needed_key, up->encap_enabled
is not set in rxrpc_open_socket(), and it will cause encap_needed_key
not being decreased in udpv6_destroy_sock().

This patch is to improve it by just calling udp_tunnel_encap_enable()
where it increases both UDP and UDPv6 encap_needed_key and sets
up->encap_enabled.

v4->v5:
  - add the missing '#include <net/udp_tunnel.h>', as David Howells
    noticed.

Acked-and-tested-by: David Howells [off-list ref]
Signed-off-by: Xin Long <lucien.xin@gmail.com>

Looks good.

David

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Wed,  3 Feb 2021 16:54:21 +0800 you wrote:

Currently, udp v6 socket can not process v4 packets with UDP GRO, as
udp_encap_needed_key is not increased when udp_tunnel_encap_enable()
is called for v6 socket.

This patchset is to increase it and remove the unnecessary code in
bareudp in Patch 1/2, and improve rxrpc encap_enable by calling
udp_tunnel_encap_enable().

[...]

Here is the summary with links:
  - [PATCHv5,net-next,1/2] udp: call udp_encap_enable for v6 sockets when enabling encap
    https://git.kernel.org/netdev/net-next/c/a4a600dd301c
  - [PATCHv5,net-next,2/2] rxrpc: call udp_tunnel_encap_enable in rxrpc_open_socket
    https://git.kernel.org/netdev/net-next/c/5d30c626b67e

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

On Tue, Mar 29, 2022 at 03:24:49PM +0200, Antonio Quartulli wrote:

Hi all,

On 03/02/2021 09:54, Xin Long wrote:

quoted

When enabling encap for a ipv6 socket without udp_encap_needed_key
increased, UDP GRO won't work for v4 mapped v6 address packets as
sk will be NULL in udp4_gro_receive().

This patch is to enable it by increasing udp_encap_needed_key for
v6 sockets in udp_tunnel_encap_enable(), and correspondingly
decrease udp_encap_needed_key in udpv6_destroy_sock().

This is a non-negligible issue that other users (in or out of tree) may hit
as well.

At OpenVPN we are developing a kernel device driver that has the same
problem as UDP GRO. So far the only workaround is to let users upgrade to
v5.12+.

I would like to propose to take this patch in stable releases.
Greg, is this an option?

Commit in the linux kernel is:
a4a600dd301ccde6ea239804ec1f19364a39d643

What stable tree(s) should this apply to, and where have you tested it?

thanks,

greg k-h

Hi all,

On 03/02/2021 09:54, Xin Long wrote:

When enabling encap for a ipv6 socket without udp_encap_needed_key
increased, UDP GRO won't work for v4 mapped v6 address packets as
sk will be NULL in udp4_gro_receive().

This patch is to enable it by increasing udp_encap_needed_key for
v6 sockets in udp_tunnel_encap_enable(), and correspondingly
decrease udp_encap_needed_key in udpv6_destroy_sock().

This is a non-negligible issue that other users (in or out of tree) may 
hit as well.

At OpenVPN we are developing a kernel device driver that has the same 
problem as UDP GRO. So far the only workaround is to let users upgrade 
to v5.12+.

I would like to propose to take this patch in stable releases.
Greg, is this an option?

Commit in the linux kernel is:
a4a600dd301ccde6ea239804ec1f19364a39d643

Thanks a lot.

Best Regards,

-- 
Antonio Quartulli
OpenVPN Inc.

Hi,

On 29/03/2022 15:30, Greg Kroah-Hartman wrote:

quoted

I would like to propose to take this patch in stable releases.
Greg, is this an option?

Commit in the linux kernel is:
a4a600dd301ccde6ea239804ec1f19364a39d643

What stable tree(s) should this apply to, and where have you tested it?

Sorry for the delay, Greg, but I wanted to run some extra tests on the 
various longterm kernel releases.

This bug exists since "ever", therefore ideally it could/should be 
applied to all stable trees.

However, this patch applies as-is only to v5.10 and v5.4 (you need to 
ignore the hunk for 'drivers/net/bareudp.c' on the latter).

Older trees require a different code change.

My tests on v5.10 and v5.4 show that the patch works as expected.

Therefore, could it be backported to these 2 trees?
It can get my

Tested-by: Antonio Quartulli <antonio@openvpn.net>

Thanks a lot,

-- 
Antonio Quartulli
OpenVPN Inc.

On Thu, Mar 31, 2022 at 03:06:41PM +0200, Antonio Quartulli wrote:

Hi,

On 29/03/2022 15:30, Greg Kroah-Hartman wrote:

quoted

quoted

I would like to propose to take this patch in stable releases.
Greg, is this an option?

Commit in the linux kernel is:
a4a600dd301ccde6ea239804ec1f19364a39d643

What stable tree(s) should this apply to, and where have you tested it?

Sorry for the delay, Greg, but I wanted to run some extra tests on the
various longterm kernel releases.

This bug exists since "ever", therefore ideally it could/should be applied
to all stable trees.

However, this patch applies as-is only to v5.10 and v5.4 (you need to ignore
the hunk for 'drivers/net/bareudp.c' on the latter).

Older trees require a different code change.

My tests on v5.10 and v5.4 show that the patch works as expected.

Therefore, could it be backported to these 2 trees?
It can get my

Tested-by: Antonio Quartulli <antonio@openvpn.net>

Now queued up, thanks.

greg k-h