[PATCH] libosmocore[master]: Enable GnuTLS fallback

[Max]

Hello Jenkins Builder,

I'd like you to reexamine a change.  Please visit

    https://gerrit.osmocom.org/4593

to look at the new patch set (#2).

Enable GnuTLS fallback

On systems with GNU/Linux kernel older than 3.17 (Debian 8 "jessie" for
example) the osmo_get_rand_id() would always return failure. To support
such systems, let's add fallback code which uses GnuTLS library. It have
to be enabled explicitly via '--enable-gnutls' option at compile-time.

Related: OS#1694

Change-Id: Ic77866ce65acf524b768882c751a4f9c0635740b
---
M configure.ac
M src/gsm/Makefile.am
M src/gsm/gsm_utils.c
3 files changed, 33 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/93/4593/2

diff --git a/configure.ac b/configure.ac
index d9390cf..4cfc451 100644
--- a/configure.ac
+++ b/configure.ac
@@ -130,6 +130,24 @@
 AM_CONDITIONAL(ENABLE_PCSC, test "x$ENABLE_PCSC" = "xyes")
 AC_SUBST(ENABLE_PCSC)
 
+AC_ARG_ENABLE(gnutls,
+	[AS_HELP_STRING(
+		[--enable-gnutls],
+		[Enable support for the GnuTLS fallback for missing getrandom()],
+	)],
+	[ENABLE_GNUTLS=$enableval], [ENABLE_GNUTLS="no"])
+AM_CONDITIONAL(ENABLE_GNUTLS, test x"$ENABLE_GNUTLS" = x"yes")
+AS_IF([test "x$ENABLE_GNUTLS" = "xyes"], [
+	PKG_CHECK_MODULES([LIBGNUTLS], [gnutls >= 2.12.0])
+])
+AC_SUBST(ENABLE_GNUTLS)
+if test x"$ENABLE_GNUTLS" = x"yes"
+then
+	AC_SUBST([LIBGNUTLS_CFLAGS])
+	AC_SUBST([LIBGNUTLS_LIBS])
+	AC_DEFINE([USE_GNUTLS], [1], [Use GnuTLS as a fallback for missing getrandom()])
+fi
+
 AC_ARG_ENABLE(plugin,
 	[AS_HELP_STRING(
 		[--disable-plugin],
@@ -228,6 +246,7 @@
 	AM_CONDITIONAL(ENABLE_PLUGIN, false)
 	AM_CONDITIONAL(ENABLE_MSGFILE, false)
 	AM_CONDITIONAL(ENABLE_SERIAL, false)
+	AM_CONDITIONAL(ENABLE_GNUTLS, false)
 	AM_CONDITIONAL(ENABLE_VTY, false)
 	AM_CONDITIONAL(ENABLE_CTRL, false)
 	AM_CONDITIONAL(ENABLE_UTILITIES, false)
diff --git a/src/gsm/Makefile.am b/src/gsm/Makefile.am
index 4476971..12f56db 100644
--- a/src/gsm/Makefile.am
+++ b/src/gsm/Makefile.am
@@ -38,6 +38,11 @@
 libosmogsm_la_LDFLAGS = $(LTLDFLAGS_OSMOGSM) -version-info $(LIBVERSION) -no-undefined
 libosmogsm_la_LIBADD = libgsmint.la $(TALLOC_LIBS)
 
+if ENABLE_GNUTLS
+AM_CPPFLAGS += $(LIBGNUTLS_CFLAGS)
+libosmogsm_la_LIBADD += $(LIBGNUTLS_LIBS)
+endif
+
 EXTRA_DIST = libosmogsm.map
 
 # Convolutional codes generation
diff --git a/src/gsm/gsm_utils.c b/src/gsm/gsm_utils.c
index e3f792e..f57d826 100644
--- a/src/gsm/gsm_utils.c
+++ b/src/gsm/gsm_utils.c
@@ -104,6 +104,10 @@
 #ifndef GRND_NONBLOCK
 #define GRND_NONBLOCK 0x0001
 #endif
+#elif (USE_GNUTLS)
+#pragma message ("Secure random unavailable: including GnuTLS.")
+#include <gnutls/gnutls.h>
+#include <gnutls/crypto.h>
 #endif
 
 /* ETSI GSM 03.38 6.2.1 and 6.2.1.1 default alphabet
@@ -422,7 +426,12 @@
 	/* FIXME: this can be removed once we bump glibc requirements to 2.25: */
 	rc = syscall(SYS_getrandom, out, len, GRND_NONBLOCK);
 #else
+#if (USE_GNUTLS)
+#pragma message ("Secure random unavailable: using GnuTLS fallback.")
+	return gnutls_rnd(GNUTLS_RND_RANDOM, out, len);
+#else
 #pragma message ("Secure random unavailable: calls to osmo_get_rand_id() will always fail!")
+#endif
 	return -ENOTSUP;
 #endif
 	/* getrandom() failed entirely: */

-- 
To view, visit https://gerrit.osmocom.org/4593
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Ic77866ce65acf524b768882c751a4f9c0635740b
Gerrit-PatchSet: 2
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Owner: Max <msuraev at sysmocom.de>
Gerrit-Reviewer: Jenkins Builder