Use arc4random_buf() instead of RAND_bytes() or RAND_pseudo_bytes().

arc4random provides high quality pseudo-random numbers, hence there is no
need to differentiate between "strong" and "pseudo". Furthermore, the
arc4random_buf() function is guaranteed to succeed, which avoids the need
to check for and handle failure, simplifying the code.

It is worth noting that a number of the replaced RAND_bytes() and
RAND_pseudo_bytes() calls were missing return value checks and these
functions can fail for a number of reasons (at least in OpenSSL -
thankfully they were converted to wrappers around arc4random_buf() some
time ago in LibreSSL).

ok beck@ deraadt@ miod@

1 files changed, 4 insertions, 7 deletions

diff --git a/src/lib/libssl/s3_clnt.c b/src/lib/libssl/s3_clnt.c
index 9aa599a1c6..179e9400d4 100644
--- a/src/lib/libssl/s3_clnt.c
+++ b/src/lib/libssl/s3_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: s3_clnt.c,v 1.91 2014/09/27 11:01:05 jsing Exp $ */
+/* $OpenBSD: s3_clnt.c,v 1.92 2014/10/18 16:13:16 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -151,7 +151,6 @@
 #include <stdio.h>
 #include "ssl_locl.h"
 #include <openssl/buffer.h>
-#include <openssl/rand.h>
 #include <openssl/objects.h>
 #include <openssl/evp.h>
 #include <openssl/md5.h>
@@ -657,8 +656,7 @@ ssl3_client_hello(SSL *s)
                 }
                 /* else use the pre-loaded session */
 
-                p = s->s3->client_random;
-                RAND_pseudo_bytes(p, SSL3_RANDOM_SIZE);
+                arc4random_buf(s->s3->client_random, SSL3_RANDOM_SIZE);
 
                 /* Do the message type and length last */
                 d = p = &buf[4];
@@ -1990,8 +1988,7 @@ ssl3_send_client_key_exchange(SSL *s)
 
                         tmp_buf[0] = s->client_version >> 8;
                         tmp_buf[1] = s->client_version & 0xff;
-                        if (RAND_bytes(&(tmp_buf[2]), sizeof tmp_buf - 2) <= 0)
-                                goto err;
+                        arc4random_buf(&tmp_buf[2], sizeof(tmp_buf) - 2);
 
                         s->session->master_key_length = sizeof tmp_buf;
 
@@ -2303,7 +2300,7 @@ ssl3_send_client_key_exchange(SSL *s)
 
                         EVP_PKEY_encrypt_init(pkey_ctx);
                         /* Generate session key. */
-                        RAND_bytes(premaster_secret, 32);
+                        arc4random_buf(premaster_secret, 32);
                         /*
                          * If we have client certificate, use its secret
                          * as peer key.