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, 40 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/080-wireguard-0051-crypto-chacha20poly1305-prevent-integer-overflow-on-.patch b/target/linux/generic/backport-5.4/080-wireguard-0051-crypto-chacha20poly1305-prevent-integer-overflow-on-.patch
new file mode 100644
index 0000000000..300420f6fe
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0051-crypto-chacha20poly1305-prevent-integer-overflow-on-.patch
@@ -0,0 +1,40 @@
+From dceaaf068879fc228e85c482f65ebb707587f696 Mon Sep 17 00:00:00 2001
+From: "Jason A. Donenfeld" <Jason@zx2c4.com>
+Date: Thu, 6 Feb 2020 12:42:01 +0100
+Subject: [PATCH 051/124] crypto: chacha20poly1305 - prevent integer overflow
+ on large input
+
+commit c9cc0517bba9f0213f1e55172feceb99e5512daf upstream.
+
+This code assigns src_len (size_t) to sl (int), which causes problems
+when src_len is very large. Probably nobody in the kernel should be
+passing this much data to chacha20poly1305 all in one go anyway, so I
+don't think we need to change the algorithm or introduce larger types
+or anything. But we should at least error out early in this case and
+print a warning so that we get reports if this does happen and can look
+into why anybody is possibly passing it that much data or if they're
+accidently passing -1 or similar.
+
+Fixes: d95312a3ccc0 ("crypto: lib/chacha20poly1305 - reimplement crypt_from_sg() routine")
+Cc: Ard Biesheuvel <ardb@kernel.org>
+Cc: stable@vger.kernel.org # 5.5+
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+Acked-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>
+---
+ lib/crypto/chacha20poly1305.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/lib/crypto/chacha20poly1305.c
++++ b/lib/crypto/chacha20poly1305.c
+@@ -235,6 +235,9 @@ bool chacha20poly1305_crypt_sg_inplace(s
+ 		__le64 lens[2];
+ 	} b __aligned(16);
+ 
++	if (WARN_ON(src_len > INT_MAX))
++		return false;
++
+ 	chacha_load_key(b.k, key);
+ 
+ 	b.iv[0] = 0;