Add getentropy(2) randomness source

crypto/random/seed/GetEntropyRandomSeed.c

@@ -0,0 +1,64 @@
+/* vim: set expandtab ts=4 sw=4: */
+/*
+ * You may redistribute this program and/or modify it under the terms of
+ * the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#define _GNU_SOURCE
+#include "crypto/random/seed/GetEntropyRandomSeed.h"
+#include "util/Identity.h"
+#include "util/Bits.h"
+
+#include <unistd.h>
+#include <errno.h>
+#include <sys/syscall.h>
+
+#ifndef __OPENBSD__
+static int getentropy(void *buf, size_t buflen)
+{
+    int ret;
+
+    if (buflen > 256) {
+        goto failure;
+    }
+
+    ret = syscall(SYS_getrandom, buf, buflen, 0);
+
+    if (ret < 0) {
+        return ret;
+    }
+
+    if ((size_t)ret == buflen) {
+        return 0;
+    }
+
+    failure:
+        errno = EIO;
+        return -1;
+}
+#endif
+
+static int get(struct RandomSeed* randomSeed, uint64_t output[8])
+{
+    if (getentropy(output, 64) < 0) {
+        return -1;
+    } else {
+        return 0;
+    }
+}
+
+struct RandomSeed* GetEntropyRandomSeed_new(struct Allocator* alloc)
+{
+    return Allocator_clone(alloc, (&(struct RandomSeed) {
+        .get = get,
+        .name = "getentropy(2)"
+    }));
+}

crypto/random/seed/GetEntropyRandomSeed.h

@@ -0,0 +1,31 @@
+/* vim: set expandtab ts=4 sw=4: */
+/*
+ * You may redistribute this program and/or modify it under the terms of
+ * the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef GetEntropyRandomSeed_H
+#define GetEntropyRandomSeed_H
+
+#include "crypto/random/seed/RandomSeed.h"
+#include "crypto/random/seed/RandomSeedProvider.h"
+#include "memory/Allocator.h"
+#include "util/Linker.h"
+
+#include <sys/syscall.h>
+
+#if defined __OPENBSD__ || defined SYS_getrandom
+    Linker_require("crypto/random/seed/GetEntropyRandomSeed.c")
+    struct RandomSeed* GetEntropyRandomSeed_new(struct Allocator* alloc);
+    RandomSeedProvider_register(GetEntropyRandomSeed_new)
+#endif
+
+#endif

crypto/random/seed/SystemRandomSeed.c

@@ -21,6 +21,7 @@
 #include "crypto/random/seed/DevUrandomRandomSeed.h"
 #include "crypto/random/seed/LinuxRandomUuidSysctlRandomSeed.h"
 #include "crypto/random/seed/ProcSysKernelRandomUuidRandomSeed.h"
+#include "crypto/random/seed/GetEntropyRandomSeed.h"
 
 static RandomSeed_Provider PROVIDERS[] = { RandomSeedProvider_list() };
 #define PROVIDERS_COUNT ((int)(sizeof(PROVIDERS) / sizeof(RandomSeed_Provider)))