crypto: allow default TLS priority to be chosen at build time

Modern gnutls can use a global config file to control the
crypto priority settings for TLS connections. For example
the priority string "@SYSTEM" instructs gnutls to find the
priority setting named "SYSTEM" in the global config file.

Latest gnutls GIT codebase gained the ability to reference
multiple priority strings in the config file, with the first
one that is found to existing winning. This means it is now
possible to configure QEMU out of the box with a default
priority of "@QEMU,SYSTEM", which says to look for the
settings "QEMU" first, and if not found, use the "SYSTEM"
settings.

To make use of this facility, we introduce the ability to
set the QEMU default priority at build time via a new
configure argument.  It is anticipated that distro vendors
will set this when building QEMU to a suitable value for
use with distro crypto policy setup. eg current Fedora
would run

 ./configure --tls-priority=@SYSTEM

while future Fedora would run

 ./configure --tls-priority=@QEMU,SYSTEM

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange 2016-06-06 10:05:06 +01:00
parent 13f12430d4
commit a1c5e949dd
2 changed files with 8 additions and 2 deletions

6
configure vendored
View File

@ -305,6 +305,7 @@ archipelago="no"
gtk="" gtk=""
gtkabi="" gtkabi=""
gtk_gl="no" gtk_gl="no"
tls_priority="NORMAL"
gnutls="" gnutls=""
gnutls_rnd="" gnutls_rnd=""
nettle="" nettle=""
@ -1096,6 +1097,8 @@ for opt do
;; ;;
--enable-gtk) gtk="yes" --enable-gtk) gtk="yes"
;; ;;
--tls-priority=*) tls_priority="$optarg"
;;
--disable-gnutls) gnutls="no" --disable-gnutls) gnutls="no"
;; ;;
--enable-gnutls) gnutls="yes" --enable-gnutls) gnutls="yes"
@ -1307,6 +1310,7 @@ Advanced options (experts only):
--disable-blobs disable installing provided firmware blobs --disable-blobs disable installing provided firmware blobs
--with-vss-sdk=SDK-path enable Windows VSS support in QEMU Guest Agent --with-vss-sdk=SDK-path enable Windows VSS support in QEMU Guest Agent
--with-win-sdk=SDK-path path to Windows Platform SDK (to build VSS .tlb) --with-win-sdk=SDK-path path to Windows Platform SDK (to build VSS .tlb)
--tls-priority default TLS protocol/cipher priority string
Optional features, enabled with --enable-FEATURE and Optional features, enabled with --enable-FEATURE and
disabled with --disable-FEATURE, default is enabled if available: disabled with --disable-FEATURE, default is enabled if available:
@ -4802,6 +4806,7 @@ echo "SDL support $sdl $(echo_version $sdl $sdlversion)"
echo "GTK support $gtk $(echo_version $gtk $gtk_version)" echo "GTK support $gtk $(echo_version $gtk $gtk_version)"
echo "GTK GL support $gtk_gl" echo "GTK GL support $gtk_gl"
echo "VTE support $vte $(echo_version $vte $vteversion)" echo "VTE support $vte $(echo_version $vte $vteversion)"
echo "TLS priority $tls_priority"
echo "GNUTLS support $gnutls" echo "GNUTLS support $gnutls"
echo "GNUTLS rnd $gnutls_rnd" echo "GNUTLS rnd $gnutls_rnd"
echo "libgcrypt $gcrypt" echo "libgcrypt $gcrypt"
@ -5165,6 +5170,7 @@ if test "$gtk" = "yes" ; then
echo "CONFIG_GTK_GL=y" >> $config_host_mak echo "CONFIG_GTK_GL=y" >> $config_host_mak
fi fi
fi fi
echo "CONFIG_TLS_PRIORITY=\"$tls_priority\"" >> $config_host_mak
if test "$gnutls" = "yes" ; then if test "$gnutls" = "yes" ; then
echo "CONFIG_GNUTLS=y" >> $config_host_mak echo "CONFIG_GNUTLS=y" >> $config_host_mak
fi fi

View File

@ -137,7 +137,7 @@ qcrypto_tls_session_new(QCryptoTLSCreds *creds,
if (creds->priority != NULL) { if (creds->priority != NULL) {
prio = g_strdup_printf("%s:+ANON-DH", creds->priority); prio = g_strdup_printf("%s:+ANON-DH", creds->priority);
} else { } else {
prio = g_strdup("NORMAL:+ANON-DH"); prio = g_strdup(CONFIG_TLS_PRIORITY ":+ANON-DH");
} }
ret = gnutls_priority_set_direct(session->handle, prio, NULL); ret = gnutls_priority_set_direct(session->handle, prio, NULL);
@ -167,7 +167,7 @@ qcrypto_tls_session_new(QCryptoTLSCreds *creds,
QCryptoTLSCredsX509 *tcreds = QCRYPTO_TLS_CREDS_X509(creds); QCryptoTLSCredsX509 *tcreds = QCRYPTO_TLS_CREDS_X509(creds);
const char *prio = creds->priority; const char *prio = creds->priority;
if (!prio) { if (!prio) {
prio = "NORMAL"; prio = CONFIG_TLS_PRIORITY;
} }
ret = gnutls_priority_set_direct(session->handle, prio, NULL); ret = gnutls_priority_set_direct(session->handle, prio, NULL);