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>
(cherry picked from commit 3888fa78802354ab7bbd19b7d061fd80a16ce06b)
(cherry picked from commit d54072587146dd0db9bb52b513234d944edabda3)
(cherry picked from commit 196f3d586f11d96ba4ab60068cfb12420bcd20fd)
(cherry picked from commit 3500fd7938a6d0c0e320295f0aa2fa34b1ebc08d)
(cherry picked from commit 23b801d3ba57e34cc609ea40982c7fbed08164e9)
(cherry picked from commit 0c0cb97da7f5cc06919449131dd57ed805f8f78d)
(cherry picked from commit 2a27f6f90a430342cdbe84806e8b10acff446a2d)
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/080-wireguard-0103-wireguard-noise-read-preshared-key-while-taking-lock.patch b/target/linux/generic/backport-5.4/080-wireguard-0103-wireguard-noise-read-preshared-key-while-taking-lock.patch
new file mode 100644
index 0000000000..2dac4b7064
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0103-wireguard-noise-read-preshared-key-while-taking-lock.patch
@@ -0,0 +1,61 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: "Jason A. Donenfeld" <Jason@zx2c4.com>
+Date: Tue, 19 May 2020 22:49:28 -0600
+Subject: [PATCH] wireguard: noise: read preshared key while taking lock
+
+commit bc67d371256f5c47d824e2eec51e46c8d62d022e upstream.
+
+Prior we read the preshared key after dropping the handshake lock, which
+isn't an actual crypto issue if it races, but it's still not quite
+correct. So copy that part of the state into a temporary like we do with
+the rest of the handshake state variables. Then we can release the lock,
+operate on the temporary, and zero it out at the end of the function. In
+performance tests, the impact of this was entirely unnoticable, probably
+because those bytes are coming from the same cacheline as other things
+that are being copied out in the same manner.
+
+Reported-by: Matt Dunwoodie <ncon@noconroy.net>
+Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+---
+ drivers/net/wireguard/noise.c | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+--- a/drivers/net/wireguard/noise.c
++++ b/drivers/net/wireguard/noise.c
+@@ -715,6 +715,7 @@ wg_noise_handshake_consume_response(stru
+ 	u8 e[NOISE_PUBLIC_KEY_LEN];
+ 	u8 ephemeral_private[NOISE_PUBLIC_KEY_LEN];
+ 	u8 static_private[NOISE_PUBLIC_KEY_LEN];
++	u8 preshared_key[NOISE_SYMMETRIC_KEY_LEN];
+ 
+ 	down_read(&wg->static_identity.lock);
+ 
+@@ -733,6 +734,8 @@ wg_noise_handshake_consume_response(stru
+ 	memcpy(chaining_key, handshake->chaining_key, NOISE_HASH_LEN);
+ 	memcpy(ephemeral_private, handshake->ephemeral_private,
+ 	       NOISE_PUBLIC_KEY_LEN);
++	memcpy(preshared_key, handshake->preshared_key,
++	       NOISE_SYMMETRIC_KEY_LEN);
+ 	up_read(&handshake->lock);
+ 
+ 	if (state != HANDSHAKE_CREATED_INITIATION)
+@@ -750,7 +753,7 @@ wg_noise_handshake_consume_response(stru
+ 		goto fail;
+ 
+ 	/* psk */
+-	mix_psk(chaining_key, hash, key, handshake->preshared_key);
++	mix_psk(chaining_key, hash, key, preshared_key);
+ 
+ 	/* {} */
+ 	if (!message_decrypt(NULL, src->encrypted_nothing,
+@@ -783,6 +786,7 @@ out:
+ 	memzero_explicit(chaining_key, NOISE_HASH_LEN);
+ 	memzero_explicit(ephemeral_private, NOISE_PUBLIC_KEY_LEN);
+ 	memzero_explicit(static_private, NOISE_PUBLIC_KEY_LEN);
++	memzero_explicit(preshared_key, NOISE_SYMMETRIC_KEY_LEN);
+ 	up_read(&wg->static_identity.lock);
+ 	return ret_peer;
+ }