1 files changed, 35 insertions, 1 deletions

diff --git a/openbsd-compat/arc4random.c b/openbsd-compat/arc4random.c
index 09dbfda16..046f57e61 100644
--- a/openbsd-compat/arc4random.c
+++ b/openbsd-compat/arc4random.c
@@ -26,15 +26,19 @@
 
 #include "includes.h"
 
+#include <sys/types.h>
+
+#include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <sys/types.h>
 
 #ifndef HAVE_ARC4RANDOM
 
+#ifdef WITH_OPENSSL
 #include <openssl/rand.h>
 #include <openssl/err.h>
+#endif
 
 #include "log.h"
 
@@ -73,14 +77,44 @@ _rs_init(u_char *buf, size_t n)
         chacha_ivsetup(&rs, buf + KEYSZ);
 }
 
+#ifndef WITH_OPENSSL
+#define SSH_RANDOM_DEV "/dev/urandom"
+/* XXX use getrandom() if supported on Linux */
+static void
+getrnd(u_char *s, size_t len)
+{
+        int fd;
+        ssize_t r;
+        size_t o = 0;
+
+        if ((fd = open(SSH_RANDOM_DEV, O_RDONLY)) == -1)
+                fatal("Couldn't open %s: %s", SSH_RANDOM_DEV, strerror(errno));
+        while (o < len) {
+                r = read(fd, s + o, len - o);
+                if (r < 0) {
+                        if (errno == EAGAIN || errno == EINTR ||
+                            errno == EWOULDBLOCK)
+                                continue;
+                        fatal("read %s: %s", SSH_RANDOM_DEV, strerror(errno));
+                }
+                o += r;
+        }
+        close(fd);
+}
+#endif
+
 static void
 _rs_stir(void)
 {
         u_char rnd[KEYSZ + IVSZ];
 
+#ifdef WITH_OPENSSL
         if (RAND_bytes(rnd, sizeof(rnd)) <= 0)
                 fatal("Couldn't obtain random bytes (error %ld)",
                     ERR_get_error());
+#else
+        getrnd(rnd, sizeof(rnd));
+#endif
 
         if (!rs_initialized) {
                 rs_initialized = 1;