+/*
+ * Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#define BR_ENABLE_INTRINSICS 1
+#include "inner.h"
+
+#if BR_USE_URANDOM
+#include <sys/types.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#endif
+
+#if BR_USE_WIN32_RAND
+#include <windows.h>
+#include <wincrypt.h>
+#pragma comment(lib, "advapi32")
+#endif
+
+#if BR_RDRAND
+BR_TARGETS_X86_UP
+BR_TARGET("rdrnd")
+static int
+seeder_rdrand(const br_prng_class **ctx)
+{
+ unsigned char tmp[32];
+ size_t u;
+
+ for (u = 0; u < sizeof tmp; u += sizeof(uint32_t)) {
+ int j;
+ uint32_t x;
+
+ /*
+ * We use the 32-bit intrinsic so that code is compatible
+ * with both 32-bit and 64-bit architectures.
+ *
+ * Intel recommends trying at least 10 times in case of
+ * failure.
+ */
+ for (j = 0; j < 10; j ++) {
+ if (_rdrand32_step(&x)) {
+ goto next_word;
+ }
+ }
+ return 0;
+ next_word:
+ br_enc32le(tmp + u, x);
+ }
+ (*ctx)->update(ctx, tmp, sizeof tmp);
+ return 1;
+}
+BR_TARGETS_X86_DOWN
+
+static int
+rdrand_supported(void)
+{
+ /*
+ * The RDRND support is bit 30 of ECX, as returned by CPUID.
+ */
+ return br_cpuid(0, 0, 0x40000000, 0);
+}
+
+#endif
+
+#if BR_USE_URANDOM
+static int
+seeder_urandom(const br_prng_class **ctx)
+{
+ int f;
+
+ f = open("/dev/urandom", O_RDONLY);
+ if (f >= 0) {
+ unsigned char tmp[32];
+ size_t u;
+
+ for (u = 0; u < sizeof tmp;) {
+ ssize_t len;
+
+ len = read(f, tmp + u, (sizeof tmp) - u);
+ if (len < 0) {
+ if (errno == EINTR) {
+ continue;
+ }
+ break;
+ }
+ u += (size_t)len;
+ }
+ close(f);
+ if (u == sizeof tmp) {
+ (*ctx)->update(ctx, tmp, sizeof tmp);
+ return 1;
+ }
+ }
+ return 0;
+}
+#endif
+
+#if BR_USE_WIN32_RAND
+static int
+seeder_win32(const br_prng_class **ctx)
+{
+ HCRYPTPROV hp;
+
+ if (CryptAcquireContext(&hp, 0, 0, PROV_RSA_FULL,
+ CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
+ {
+ BYTE buf[32];
+ BOOL r;
+
+ r = CryptGenRandom(hp, sizeof buf, buf);
+ CryptReleaseContext(hp, 0);
+ if (r) {
+ (*ctx)->update(ctx, buf, sizeof buf);
+ return 1;
+ }
+ }
+ return 0;
+}
+#endif
+
+/* see bearssl_rand.h.h */
+br_prng_seeder
+br_prng_seeder_system(const char **name)
+{
+#if BR_RDRAND
+ if (rdrand_supported()) {
+ if (name != NULL) {
+ *name = "rdrand";
+ }
+ return &seeder_rdrand;
+ }
+#endif
+#if BR_USE_URANDOM
+ if (name != NULL) {
+ *name = "urandom";
+ }
+ return &seeder_urandom;
+#elif BR_USE_WIN32_RAND
+ if (name != NULL) {
+ *name = "win32";
+ }
+ return &seeder_win32;
+#endif
+ if (name != NULL) {
+ *name = "none";
+ }
+ return 0;
+}
projects / BearSSL / commitdiff