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, 136 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/080-wireguard-0027-crypto-curve25519-implement-generic-KPP-driver.patch b/target/linux/generic/backport-5.4/080-wireguard-0027-crypto-curve25519-implement-generic-KPP-driver.patch
new file mode 100644
index 0000000000..d909561690
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0027-crypto-curve25519-implement-generic-KPP-driver.patch
@@ -0,0 +1,136 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ard Biesheuvel <ardb@kernel.org>
+Date: Fri, 8 Nov 2019 13:22:34 +0100
+Subject: [PATCH] crypto: curve25519 - implement generic KPP driver
+
+commit ee772cb641135739c1530647391d5a04c39db192 upstream.
+
+Expose the generic Curve25519 library via the crypto API KPP interface.
+
+Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
+Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+---
+ crypto/Kconfig              |  5 +++
+ crypto/Makefile             |  1 +
+ crypto/curve25519-generic.c | 90 +++++++++++++++++++++++++++++++++++++
+ 3 files changed, 96 insertions(+)
+ create mode 100644 crypto/curve25519-generic.c
+
+--- a/crypto/Kconfig
++++ b/crypto/Kconfig
+@@ -264,6 +264,11 @@ config CRYPTO_ECRDSA
+ 	  standard algorithms (called GOST algorithms). Only signature verification
+ 	  is implemented.
+ 
++config CRYPTO_CURVE25519
++	tristate "Curve25519 algorithm"
++	select CRYPTO_KPP
++	select CRYPTO_LIB_CURVE25519_GENERIC
++
+ comment "Authenticated Encryption with Associated Data"
+ 
+ config CRYPTO_CCM
+--- a/crypto/Makefile
++++ b/crypto/Makefile
+@@ -167,6 +167,7 @@ obj-$(CONFIG_CRYPTO_ZSTD) += zstd.o
+ obj-$(CONFIG_CRYPTO_OFB) += ofb.o
+ obj-$(CONFIG_CRYPTO_ECC) += ecc.o
+ obj-$(CONFIG_CRYPTO_ESSIV) += essiv.o
++obj-$(CONFIG_CRYPTO_CURVE25519) += curve25519-generic.o
+ 
+ ecdh_generic-y += ecdh.o
+ ecdh_generic-y += ecdh_helper.o
+--- /dev/null
++++ b/crypto/curve25519-generic.c
+@@ -0,0 +1,90 @@
++// SPDX-License-Identifier: GPL-2.0-or-later
++
++#include <crypto/curve25519.h>
++#include <crypto/internal/kpp.h>
++#include <crypto/kpp.h>
++#include <linux/module.h>
++#include <linux/scatterlist.h>
++
++static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf,
++				 unsigned int len)
++{
++	u8 *secret = kpp_tfm_ctx(tfm);
++
++	if (!len)
++		curve25519_generate_secret(secret);
++	else if (len == CURVE25519_KEY_SIZE &&
++		 crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE))
++		memcpy(secret, buf, CURVE25519_KEY_SIZE);
++	else
++		return -EINVAL;
++	return 0;
++}
++
++static int curve25519_compute_value(struct kpp_request *req)
++{
++	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
++	const u8 *secret = kpp_tfm_ctx(tfm);
++	u8 public_key[CURVE25519_KEY_SIZE];
++	u8 buf[CURVE25519_KEY_SIZE];
++	int copied, nbytes;
++	u8 const *bp;
++
++	if (req->src) {
++		copied = sg_copy_to_buffer(req->src,
++					   sg_nents_for_len(req->src,
++							    CURVE25519_KEY_SIZE),
++					   public_key, CURVE25519_KEY_SIZE);
++		if (copied != CURVE25519_KEY_SIZE)
++			return -EINVAL;
++		bp = public_key;
++	} else {
++		bp = curve25519_base_point;
++	}
++
++	curve25519_generic(buf, secret, bp);
++
++	/* might want less than we've got */
++	nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len);
++	copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
++								nbytes),
++				     buf, nbytes);
++	if (copied != nbytes)
++		return -EINVAL;
++	return 0;
++}
++
++static unsigned int curve25519_max_size(struct crypto_kpp *tfm)
++{
++	return CURVE25519_KEY_SIZE;
++}
++
++static struct kpp_alg curve25519_alg = {
++	.base.cra_name		= "curve25519",
++	.base.cra_driver_name	= "curve25519-generic",
++	.base.cra_priority	= 100,
++	.base.cra_module	= THIS_MODULE,
++	.base.cra_ctxsize	= CURVE25519_KEY_SIZE,
++
++	.set_secret		= curve25519_set_secret,
++	.generate_public_key	= curve25519_compute_value,
++	.compute_shared_secret	= curve25519_compute_value,
++	.max_size		= curve25519_max_size,
++};
++
++static int curve25519_init(void)
++{
++	return crypto_register_kpp(&curve25519_alg);
++}
++
++static void curve25519_exit(void)
++{
++	crypto_unregister_kpp(&curve25519_alg);
++}
++
++subsys_initcall(curve25519_init);
++module_exit(curve25519_exit);
++
++MODULE_ALIAS_CRYPTO("curve25519");
++MODULE_ALIAS_CRYPTO("curve25519-generic");
++MODULE_LICENSE("GPL");