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, 68 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/080-wireguard-0053-crypto-arm64-chacha-correctly-walk-through-blocks.patch b/target/linux/generic/backport-5.4/080-wireguard-0053-crypto-arm64-chacha-correctly-walk-through-blocks.patch
new file mode 100644
index 0000000000..1c8d2df2e5
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0053-crypto-arm64-chacha-correctly-walk-through-blocks.patch
@@ -0,0 +1,68 @@
+From ed61666f3b3fae43e872dc36a2c01794d7119165 Mon Sep 17 00:00:00 2001
+From: "Jason A. Donenfeld" <Jason@zx2c4.com>
+Date: Wed, 18 Mar 2020 20:27:32 -0600
+Subject: [PATCH 053/124] crypto: arm64/chacha - correctly walk through blocks
+
+commit c8cfcb78c65877313cda7bcbace624d3dbd1f3b3 upstream.
+
+Prior, passing in chunks of 2, 3, or 4, followed by any additional
+chunks would result in the chacha state counter getting out of sync,
+resulting in incorrect encryption/decryption, which is a pretty nasty
+crypto vuln: "why do images look weird on webpages?" WireGuard users
+never experienced this prior, because we have always, out of tree, used
+a different crypto library, until the recent Frankenzinc addition. This
+commit fixes the issue by advancing the pointers and state counter by
+the actual size processed. It also fixes up a bug in the (optional,
+costly) stride test that prevented it from running on arm64.
+
+Fixes: b3aad5bad26a ("crypto: arm64/chacha - expose arm64 ChaCha routine as library function")
+Reported-and-tested-by: Emil Renner Berthing <kernel@esmil.dk>
+Cc: Ard Biesheuvel <ardb@kernel.org>
+Cc: stable@vger.kernel.org # v5.5+
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+Reviewed-by: Eric Biggers <ebiggers@google.com>
+Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+---
+ arch/arm64/crypto/chacha-neon-glue.c   |  8 ++++----
+ lib/crypto/chacha20poly1305-selftest.c | 11 ++++++++---
+ 2 files changed, 12 insertions(+), 7 deletions(-)
+
+--- a/arch/arm64/crypto/chacha-neon-glue.c
++++ b/arch/arm64/crypto/chacha-neon-glue.c
+@@ -55,10 +55,10 @@ static void chacha_doneon(u32 *state, u8
+ 			break;
+ 		}
+ 		chacha_4block_xor_neon(state, dst, src, nrounds, l);
+-		bytes -= CHACHA_BLOCK_SIZE * 5;
+-		src += CHACHA_BLOCK_SIZE * 5;
+-		dst += CHACHA_BLOCK_SIZE * 5;
+-		state[12] += 5;
++		bytes -= l;
++		src += l;
++		dst += l;
++		state[12] += DIV_ROUND_UP(l, CHACHA_BLOCK_SIZE);
+ 	}
+ }
+ 
+--- a/lib/crypto/chacha20poly1305-selftest.c
++++ b/lib/crypto/chacha20poly1305-selftest.c
+@@ -9028,10 +9028,15 @@ bool __init chacha20poly1305_selftest(vo
+ 	     && total_len <= 1 << 10; ++total_len) {
+ 		for (i = 0; i <= total_len; ++i) {
+ 			for (j = i; j <= total_len; ++j) {
++				k = 0;
+ 				sg_init_table(sg_src, 3);
+-				sg_set_buf(&sg_src[0], input, i);
+-				sg_set_buf(&sg_src[1], input + i, j - i);
+-				sg_set_buf(&sg_src[2], input + j, total_len - j);
++				if (i)
++					sg_set_buf(&sg_src[k++], input, i);
++				if (j - i)
++					sg_set_buf(&sg_src[k++], input + i, j - i);
++				if (total_len - j)
++					sg_set_buf(&sg_src[k++], input + j, total_len - j);
++				sg_init_marker(sg_src, k);
+ 				memset(computed_output, 0, total_len);
+ 				memset(input, 0, total_len);
+