crypto: add cryptographic random byte source

There are three backend impls provided. The preferred
is gnutls, which is backed by nettle in modern distros.
The gcrypt impl is provided for cases where QEMU build
against gnutls is disabled, but crypto is still desired.
No nettle impl is provided, since it is non-trivial to
use the nettle APIs for random numbers. Users of nettle
should ensure gnutls is enabled for QEMU.

Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

diff --git a/Makefile.objs b/Makefile.objs
index fbcaa7471f68fa82d6ff1aa455c0f845beb5722a..8f705f6202e681e0bd5ca943ab3d7631245e5824 100644 (file)
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -1,6 +1,6 @@
 #######################################################################
 # Common libraries for tools and emulators
-stub-obj-y = stubs/
+stub-obj-y = stubs/ crypto/
 util-obj-y = util/ qobject/ qapi/
 util-obj-y += qmp-introspect.o qapi-types.o qapi-visit.o qapi-event.o
 

diff --git a/configure b/configure
index 2b3287641adab3a1d925aad48dfa5916f97d3940..71c1e2b1b9147e03654a4941ff0307923351fd28 100755 (executable)
--- a/configure
+++ b/configure
@@ -306,6 +306,7 @@ gtkabi=""
 gtk_gl="no"
 gnutls=""
 gnutls_hash=""
+gnutls_rnd=""
 nettle=""
 gcrypt=""
 vte=""
@@ -2201,6 +2202,13 @@ if test "$gnutls" != "no"; then
            gnutls_hash="no"
        fi
 
+       # gnutls_rnd requires >= 2.11.0
+       if $pkg_config --exists "gnutls >= 2.11.0"; then
+           gnutls_rnd="yes"
+       else
+           gnutls_rnd="no"
+       fi
+
        if $pkg_config --exists 'gnutls >= 3.0'; then
            gnutls_gcrypt=no
            gnutls_nettle=yes
@@ -2228,9 +2236,11 @@ if test "$gnutls" != "no"; then
     else
         gnutls="no"
         gnutls_hash="no"
+        gnutls_rnd="no"
     fi
 else
     gnutls_hash="no"
+    gnutls_rnd="no"
 fi
 
 
@@ -4714,6 +4724,7 @@ echo "GTK support       $gtk"
 echo "GTK GL support    $gtk_gl"
 echo "GNUTLS support    $gnutls"
 echo "GNUTLS hash       $gnutls_hash"
+echo "GNUTLS rnd        $gnutls_rnd"
 echo "libgcrypt         $gcrypt"
 if test "$nettle" = "yes"; then
     echo "nettle            $nettle ($nettle_version)"
@@ -5092,6 +5103,9 @@ fi
 if test "$gnutls_hash" = "yes" ; then
   echo "CONFIG_GNUTLS_HASH=y" >> $config_host_mak
 fi
+if test "$gnutls_rnd" = "yes" ; then
+  echo "CONFIG_GNUTLS_RND=y" >> $config_host_mak
+fi
 if test "$gcrypt" = "yes" ; then
   echo "CONFIG_GCRYPT=y" >> $config_host_mak
 fi

diff --git a/crypto/Makefile.objs b/crypto/Makefile.objs
index a3135f1ddf03b2042db7ea874c68493612f631d6..967418c67af04ffdd121cb145ebd33e4b0add0db 100644 (file)
--- a/crypto/Makefile.objs
+++ b/crypto/Makefile.objs
@@ -8,6 +8,10 @@ crypto-obj-y += tlscredsanon.o
 crypto-obj-y += tlscredsx509.o
 crypto-obj-y += tlssession.o
 crypto-obj-y += secret.o
+crypto-obj-$(CONFIG_GCRYPT) += random-gcrypt.o
+crypto-obj-$(if $(CONFIG_GCRYPT),n,$(CONFIG_GNUTLS_RND)) += random-gnutls.o
 
 # Let the userspace emulators avoid linking gnutls/etc
 crypto-aes-obj-y = aes.o
+
+stub-obj-y += random-stub.o

diff --git a/crypto/random-gcrypt.c b/crypto/random-gcrypt.c
new file mode 100644 (file)
index 0000000..0de9a09
--- /dev/null
+++ b/crypto/random-gcrypt.c
@@ -0,0 +1,33 @@
+/*
+ * QEMU Crypto random number provider
+ *
+ * Copyright (c) 2015-2016 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+
+#include "crypto/random.h"
+
+#include <gcrypt.h>
+
+int qcrypto_random_bytes(uint8_t *buf,
+                         size_t buflen,
+                         Error **errp G_GNUC_UNUSED)
+{
+    gcry_randomize(buf, buflen, GCRY_STRONG_RANDOM);
+    return 0;
+}

diff --git a/crypto/random-gnutls.c b/crypto/random-gnutls.c
new file mode 100644 (file)
index 0000000..04b45a8
--- /dev/null
+++ b/crypto/random-gnutls.c
@@ -0,0 +1,43 @@
+/*
+ * QEMU Crypto random number provider
+ *
+ * Copyright (c) 2015-2016 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+
+#include "crypto/random.h"
+
+#include <gnutls/gnutls.h>
+#include <gnutls/crypto.h>
+
+int qcrypto_random_bytes(uint8_t *buf,
+                         size_t buflen,
+                         Error **errp)
+{
+    int ret;
+
+    ret = gnutls_rnd(GNUTLS_RND_RANDOM, buf, buflen);
+
+    if (ret < 0) {
+        error_setg(errp, "Cannot get random bytes: %s",
+                   gnutls_strerror(ret));
+        return -1;
+    }
+
+    return 0;
+}

diff --git a/crypto/random-stub.c b/crypto/random-stub.c
new file mode 100644 (file)
index 0000000..63bbf41
--- /dev/null
+++ b/crypto/random-stub.c
@@ -0,0 +1,31 @@
+/*
+ * QEMU Crypto random number provider
+ *
+ * Copyright (c) 2015-2016 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+
+#include "crypto/random.h"
+
+int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED,
+                         size_t buflen G_GNUC_UNUSED,
+                         Error **errp)
+{
+    error_setg(errp, "No random byte source provided in this build");
+    return -1;
+}

diff --git a/include/crypto/random.h b/include/crypto/random.h
new file mode 100644 (file)
index 0000000..b3021c4
--- /dev/null
+++ b/include/crypto/random.h
@@ -0,0 +1,44 @@
+/*
+ * QEMU Crypto random number provider
+ *
+ * Copyright (c) 2015-2016 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef QCRYPTO_RANDOM_H__
+#define QCRYPTO_RANDOM_H__
+
+#include "qemu-common.h"
+#include "qapi/error.h"
+
+
+/**
+ * qcrypto_random_bytes:
+ * @buf: the buffer to fill
+ * @buflen: length of @buf in bytes
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Fill @buf with @buflen bytes of cryptographically strong
+ * random data
+ *
+ * Returns 0 on sucess, -1 on error
+ */
+int qcrypto_random_bytes(uint8_t *buf,
+                         size_t buflen,
+                         Error **errp);
+
+
+#endif /* QCRYPTO_RANDOM_H__ */