From 48f0bfc70363ca31c8889ca68759e587bc6d7cbd Mon Sep 17 00:00:00 2001
From: Aris Adamantiadis <aris@0xbadc0de.be>
Date: Wed, 5 Feb 2014 21:24:12 +0100
Subject: security: fix for vulnerability CVE-2014-0017

When accepting a new connection, a forking server based on libssh forks
and the child process handles the request. The RAND_bytes() function of
openssl doesn't reset its state after the fork, but simply adds the
current process id (getpid) to the PRNG state, which is not guaranteed
to be unique.
This can cause several children to end up with same PRNG state which is
a security issue.

Conflicts:
	src/bind.c
---
 include/libssh/wrapper.h | 1 +
 src/bind.c               | 3 ++-
 src/libcrypto.c          | 9 +++++++++
 src/libgcrypt.c          | 3 +++
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/libssh/wrapper.h b/include/libssh/wrapper.h
index 8c034970..b8cd4d27 100644
--- a/include/libssh/wrapper.h
+++ b/include/libssh/wrapper.h
@@ -44,5 +44,6 @@ int crypt_set_algorithms_server(ssh_session session);
 struct ssh_crypto_struct *crypto_new(void);
 void crypto_free(struct ssh_crypto_struct *crypto);
 
+void ssh_reseed(void);
 
 #endif /* WRAPPER_H_ */
diff --git a/src/bind.c b/src/bind.c
index cc79f8eb..cdcdabe1 100644
--- a/src/bind.c
+++ b/src/bind.c
@@ -374,7 +374,8 @@ int ssh_bind_accept(ssh_bind sshbind, ssh_session session) {
   ssh_socket_get_poll_handle_out(session->socket);
   session->dsa_key = dsa;
   session->rsa_key = rsa;
-
+  /* force PRNG to change state in case we fork after ssh_bind_accept */
+  ssh_reseed();
   return SSH_OK;
 }
 
diff --git a/src/libcrypto.c b/src/libcrypto.c
index f43a91eb..0932cbea 100644
--- a/src/libcrypto.c
+++ b/src/libcrypto.c
@@ -23,6 +23,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <sys/time.h>
 
 #include "libssh/priv.h"
 #include "libssh/session.h"
@@ -38,6 +39,8 @@
 #include <openssl/rsa.h>
 #include <openssl/hmac.h>
 #include <openssl/opensslv.h>
+#include <openssl/rand.h>
+
 #ifdef HAVE_OPENSSL_AES_H
 #define HAS_AES
 #include <openssl/aes.h>
@@ -66,6 +69,12 @@ static int alloc_key(struct crypto_struct *cipher) {
     return 0;
 }
 
+void ssh_reseed(void){
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    RAND_add(&tv, sizeof(tv), 0.0);
+}
+
 SHACTX sha1_init(void) {
   SHACTX c = malloc(sizeof(*c));
   if (c == NULL) {
diff --git a/src/libgcrypt.c b/src/libgcrypt.c
index f8fe96f2..9a7ea431 100644
--- a/src/libgcrypt.c
+++ b/src/libgcrypt.c
@@ -41,6 +41,9 @@ static int alloc_key(struct crypto_struct *cipher) {
     return 0;
 }
 
+void ssh_reseed(void){
+	}
+
 SHACTX sha1_init(void) {
   SHACTX ctx = NULL;
   gcry_md_open(&ctx, GCRY_MD_SHA1, 0);
-- 
cgit