wolfcrypt shim for wireguard userspace tools

.gitignore

@@ -12,3 +12,4 @@ src/wg.exe
 *.til
 *.pro.user
 maint/
+*~

src/Makefile

@@ -62,6 +62,11 @@ LDLIBS += -lws2_32
 wg: wincompat/libc.o wincompat/init.o
 endif
 
+ifdef WOLFCRYPT
+CFLAGS += -DUSE_WOLFCRYPT $(shell PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:${PKG_CONFIG_PATH} $(PKG_CONFIG) --cflags wolfssl)
+LDLIBS += $(shell PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:${PKG_CONFIG_PATH} $(PKG_CONFIG) --libs wolfssl)
+endif
+
 ifneq ($(V),1)
 BUILT_IN_LINK.o := $(LINK.o)
 LINK.o = @echo "  LD      $@";
@@ -73,7 +78,11 @@ BUILT_IN_RM := $(RM)
 RM := @a() { echo "  CLEAN   $$@"; $(BUILT_IN_RM) "$$@"; }; a
 endif
 
-wg: $(sort $(patsubst %.c,%.o,$(wildcard *.c)))
+ifdef WOLFCRYPT
+wg: $(sort $(patsubst %.c,%.o,wolfcrypto_shim.c $(filter-out curve25519.c genkey.c, $(wildcard *.c))))
+else
+wg: $(sort $(patsubst %.c,%.o,$(filter-out wolfcrypto_shim.c, $(wildcard *.c))))
+endif
 
 clean:
 	$(RM) wg *.o *.d

src/curve25519.h

@@ -6,6 +6,10 @@
 #ifndef CURVE25519_H
 #define CURVE25519_H
 
+#ifdef USE_WOLFCRYPT
+#include "wolfcrypto_shim.h"
+#else
+
 #include <stdint.h>
 #include <sys/types.h>
 
@@ -22,3 +26,4 @@ static inline void curve25519_clamp_secret(uint8_t secret[static CURVE25519_KEY_
 }
 
 #endif
+#endif

src/wolfcrypto_shim.c

@@ -0,0 +1,67 @@
+#include "wolfcrypto_shim.h"
+#include "encoding.h"
+#include "subcommands.h"
+#include "containers.h"
+
+void curve25519_generate_public_wolfshim(uint8_t pub[static CURVE25519_KEY_SIZE], const uint8_t secret[static CURVE25519_KEY_SIZE]) {
+    uint8_t secret_copy[CURVE25519_KEY_SIZE]; /* pubkey_main() calls curve25519_generate_public() with pub == secret, which doesn't work for wc_curve25519_make_pub(). */
+    XMEMCPY(secret_copy, secret, CURVE25519_KEY_SIZE);
+    int ret = wc_curve25519_make_pub(CURVE25519_KEY_SIZE, pub, CURVE25519_KEY_SIZE, secret_copy);
+    if (ret) {
+        fprintf(stderr,"curve25519 public key calculation failed: %s\n", wc_GetErrorString(ret));
+        abort();
+    }
+    return;
+}
+
+int genkey_main(int argc, char *argv[]) {
+    WC_RNG gRng;
+    char base64[WG_KEY_LEN_BASE64];
+    struct stat stat;
+
+    if (argc != 1) {
+        fprintf(stderr, "Usage: %s %s\n", PROG_NAME, argv[0]);
+        return 1;
+    }
+
+    if (!fstat(STDOUT_FILENO, &stat) && S_ISREG(stat.st_mode) && stat.st_mode & S_IRWXO)
+        fputs("Warning: writing to world accessible file.\nConsider setting the umask to 077 and trying again.\n", stderr);
+
+    {
+#ifndef HAVE_FIPS
+        int ret = wc_InitRng_ex(&gRng, NULL /* HEAP_HINT */, INVALID_DEVID);
+#else
+        int ret = wc_InitRng(&gRng);
+#endif
+        if (ret != 0) {
+            fprintf(stderr,"InitRNG failed: %s\n", wc_GetErrorString(ret));
+            return 1;
+        }
+    }
+
+    if (! strcmp(argv[0],"genkey")) {
+        curve25519_key key;
+        int ret = wc_curve25519_init(&key);
+        if (ret != 0) {
+            fprintf(stderr,"wc_curve25519_init failed: %s\n", wc_GetErrorString(ret));
+            return 1;
+        }
+        ret = wc_curve25519_make_key(&gRng, CURVE25519_KEY_SIZE, &key);
+        if (ret != 0) {
+            fprintf(stderr,"wc_curve25519_make_key failed: %s\n", wc_GetErrorString(ret));
+            return 1;
+        }
+        key_to_base64(base64, key.k.point);
+    } else {
+        uint8_t key[WG_KEY_LEN];
+        int ret = wc_RNG_GenerateBlock(&gRng, key, sizeof key);
+        if (ret != 0) {
+            fprintf(stderr,"wc_RNG_GenerateBlock failed: %s\n", wc_GetErrorString(ret));
+            return 1;
+        }
+        key_to_base64(base64, key);
+    }
+
+    puts(base64);
+    return 0;
+}

src/wolfcrypto_shim.h

@@ -0,0 +1,17 @@
+#ifndef WOLFCRYPTO_SHIM_H
+#define WOLFCRYPTO_SHIM_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <wolfssl/options.h>
+#include <wolfssl/wolfcrypt/settings.h>
+#include <wolfssl/wolfcrypt/error-crypt.h>
+#include <wolfssl/wolfcrypt/curve25519.h>
+
+#define CURVE25519_KEY_SIZE CURVE25519_KEYSIZE
+
+#define curve25519_generate_public curve25519_generate_public_wolfshim
+void curve25519_generate_public_wolfshim(uint8_t pub[static CURVE25519_KEY_SIZE], const uint8_t secret[static CURVE25519_KEY_SIZE]);
+
+#endif