kernel: 5.4: import wireguard backport

Rather than using the clunky, old, slower wireguard-linux-compat out of
tree module, this commit does a patch-by-patch backport of upstream's
wireguard to 5.4. This specific backport is in widespread use, being
part of SUSE's enterprise kernel, Oracle's enterprise kernel, Google's
Android kernel, Gentoo's distro kernel, and probably more I've forgotten
about. It's definately the "more proper" way of adding wireguard to a
kernel than the ugly compat.h hell of the wireguard-linux-compat repo.
And most importantly for OpenWRT, it allows using the same module
configuration code for 5.10 as for 5.4, with no need for bifurcation.

These patches are from the backport tree which is maintained in the
open here: https://git.zx2c4.com/wireguard-linux/log/?h=backport-5.4.y
I'll be sending PRs to update this as needed.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/080-wireguard-0119-wireguard-socket-remove-bogus-__be32-annotation.patch b/target/linux/generic/backport-5.4/080-wireguard-0119-wireguard-socket-remove-bogus-__be32-annotation.patch
new file mode 100644
index 0000000000..c497ce5719
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0119-wireguard-socket-remove-bogus-__be32-annotation.patch
@@ -0,0 +1,52 @@
+From 03928cbd7e0c7906c7ab2a490e31d89d6ae3965a Mon Sep 17 00:00:00 2001
+From: Jann Horn <jannh@google.com>
+Date: Mon, 22 Feb 2021 17:25:44 +0100
+Subject: [PATCH 119/124] wireguard: socket: remove bogus __be32 annotation
+
+commit 7f57bd8dc22de35ddd895294aa554003e4f19a72 upstream.
+
+The endpoint->src_if4 has nothing to do with fixed-endian numbers; remove
+the bogus annotation.
+
+This was introduced in
+https://git.zx2c4.com/wireguard-monolithic-historical/commit?id=14e7d0a499a676ec55176c0de2f9fcbd34074a82
+in the historical WireGuard repo because the old code used to
+zero-initialize multiple members as follows:
+
+    endpoint->src4.s_addr = endpoint->src_if4 = fl.saddr = 0;
+
+Because fl.saddr is fixed-endian and an assignment returns a value with the
+type of its left operand, this meant that sparse detected an assignment
+between values of different endianness.
+
+Since then, this assignment was already split up into separate statements;
+just the cast survived.
+
+Signed-off-by: Jann Horn <jannh@google.com>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+---
+ drivers/net/wireguard/socket.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/drivers/net/wireguard/socket.c
++++ b/drivers/net/wireguard/socket.c
+@@ -53,7 +53,7 @@ static int send4(struct wg_device *wg, s
+ 		if (unlikely(!inet_confirm_addr(sock_net(sock), NULL, 0,
+ 						fl.saddr, RT_SCOPE_HOST))) {
+ 			endpoint->src4.s_addr = 0;
+-			*(__force __be32 *)&endpoint->src_if4 = 0;
++			endpoint->src_if4 = 0;
+ 			fl.saddr = 0;
+ 			if (cache)
+ 				dst_cache_reset(cache);
+@@ -63,7 +63,7 @@ static int send4(struct wg_device *wg, s
+ 			     PTR_ERR(rt) == -EINVAL) || (!IS_ERR(rt) &&
+ 			     rt->dst.dev->ifindex != endpoint->src_if4)))) {
+ 			endpoint->src4.s_addr = 0;
+-			*(__force __be32 *)&endpoint->src_if4 = 0;
++			endpoint->src_if4 = 0;
+ 			fl.saddr = 0;
+ 			if (cache)
+ 				dst_cache_reset(cache);