From 6006d4467471ed5893cfb2bd27ca054ac8351705 Mon Sep 17 00:00:00 2001
From: noctuum <25441068+noctuum@users.noreply.github.com>
Date: Fri, 6 Mar 2026 06:40:36 +0700
Subject: [PATCH] compat: fix compilation on kernels >= 6.19 (blake2s API
 change)

Kernel 6.19 refactored the blake2s API in include/crypto/blake2s.h:
- struct blake2s_state was renamed to blake2s_ctx
- blake2s() argument order changed from (out, in, key, outlen, inlen, keylen)
  to (key, keylen, in, inlen, out, outlen)

Add a compat macro to alias blake2s_state to blake2s_ctx, and guard the
three blake2s() call sites in noise.c and cookie.c with ifdef to use the
correct argument order depending on kernel version.

Tested on kernel 6.19.6-zen1-1-zen (Arch Linux).
---
 src/compat/compat.h | 6 ++++++
 src/cookie.c        | 8 ++++++++
 src/noise.c         | 5 +++++
 3 files changed, 19 insertions(+)

diff --git a/src/compat/compat.h b/src/compat/compat.h
index 4962b8f5..db8a6b4e 100644
--- a/src/compat/compat.h
+++ b/src/compat/compat.h
@@ -1399,4 +1399,10 @@ static inline char *nla_strdup(const struct nlattr *nla, gfp_t flags)
 #define COMPAT_CANNOT_USE_NETLINK_MCGRPS
 #endif
 
+/* Kernel 6.19+ renamed blake2s_state to blake2s_ctx and changed blake2s() arg order */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 19, 0)
+#define blake2s_state blake2s_ctx
+#define COMPAT_BLAKE2S_NEW_API
+#endif
+
 #endif /* _WG_COMPAT_H */
diff --git a/src/cookie.c b/src/cookie.c
index 9365c4c3..e8cf5b88 100644
--- a/src/cookie.c
+++ b/src/cookie.c
@@ -77,7 +77,11 @@ static void compute_mac1(u8 mac1[COOKIE_LEN], const void *message, size_t len,
 {
 	len = len - sizeof(struct message_macs) +
 	      offsetof(struct message_macs, mac1);
+#ifdef COMPAT_BLAKE2S_NEW_API
+	blake2s(key, NOISE_SYMMETRIC_KEY_LEN, message, len, mac1, COOKIE_LEN);
+#else
 	blake2s(mac1, message, key, COOKIE_LEN, len, NOISE_SYMMETRIC_KEY_LEN);
+#endif
 }
 
 static void compute_mac2(u8 mac2[COOKIE_LEN], const void *message, size_t len,
@@ -85,7 +89,11 @@ static void compute_mac2(u8 mac2[COOKIE_LEN], const void *message, size_t len,
 {
 	len = len - sizeof(struct message_macs) +
 	      offsetof(struct message_macs, mac2);
+#ifdef COMPAT_BLAKE2S_NEW_API
+	blake2s(cookie, COOKIE_LEN, message, len, mac2, COOKIE_LEN);
+#else
 	blake2s(mac2, message, cookie, COOKIE_LEN, len, COOKIE_LEN);
+#endif
 }
 
 static void make_cookie(u8 cookie[COOKIE_LEN], struct sk_buff *skb,
diff --git a/src/noise.c b/src/noise.c
index c3915eff..65255f8b 100644
--- a/src/noise.c
+++ b/src/noise.c
@@ -38,8 +38,13 @@ void __init wg_noise_init(void)
 {
 	struct blake2s_state blake;
 
+#ifdef COMPAT_BLAKE2S_NEW_API
+	blake2s(NULL, 0, handshake_name, sizeof(handshake_name),
+		handshake_init_chaining_key, NOISE_HASH_LEN);
+#else
 	blake2s(handshake_init_chaining_key, handshake_name, NULL,
 		NOISE_HASH_LEN, sizeof(handshake_name), 0);
+#endif
 	blake2s_init(&blake, NOISE_HASH_LEN);
 	blake2s_update(&blake, handshake_init_chaining_key, NOISE_HASH_LEN);
 	blake2s_update(&blake, identifier_name, sizeof(identifier_name));