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authorHolger Hans Peter Freyther <holger@moiji-mobile.com>2015-07-01 08:34:16 +0200
committerHolger Hans Peter Freyther <holger@moiji-mobile.com>2015-07-01 08:34:16 +0200
commit9f95ae888589dfddfe1fd325d0fb2f8361f03fab (patch)
treee2e7e132ea1a0483c1b7bec4910aa4f99e1fd8e6
parent8ee53ed9ec5e5f045778ab8b30f10cb86ec55c4a (diff)
nat: Use RAND_bytes instead of /dev/urandom
We don't need to consume all the entropy of the kernel but can use libcrypto (OpenSSL) to generate random data. It is not clear if we need to call RAND_load_file but I think we can assume that our Unices have a /dev/urandom. This takes less CPU time, provides good enough entropy (in theory) and leaves some in the kernel entropy pool.
-rw-r--r--openbsc/configure.ac1
-rw-r--r--openbsc/include/openbsc/bsc_nat.h3
-rw-r--r--openbsc/src/osmo-bsc_nat/Makefile.am4
-rw-r--r--openbsc/src/osmo-bsc_nat/bsc_nat.c24
4 files changed, 8 insertions, 24 deletions
diff --git a/openbsc/configure.ac b/openbsc/configure.ac
index fb6feb9..0af573a 100644
--- a/openbsc/configure.ac
+++ b/openbsc/configure.ac
@@ -35,6 +35,7 @@ AC_ARG_ENABLE([nat], [AS_HELP_STRING([--enable-nat], [Build the BSC NAT. Require
[osmo_ac_build_nat="$enableval"],[osmo_ac_build_nat="no"])
if test "$osmo_ac_build_nat" = "yes" ; then
PKG_CHECK_MODULES(LIBOSMOSCCP, libosmo-sccp >= 0.0.2)
+ PKG_CHECK_MODULES(LIBCRYPTO, libcrypto)
fi
AM_CONDITIONAL(BUILD_NAT, test "x$osmo_ac_build_nat" = "xyes")
AC_SUBST(osmo_ac_build_nat)
diff --git a/openbsc/include/openbsc/bsc_nat.h b/openbsc/include/openbsc/bsc_nat.h
index 72773a9..3090eb0 100644
--- a/openbsc/include/openbsc/bsc_nat.h
+++ b/openbsc/include/openbsc/bsc_nat.h
@@ -307,9 +307,6 @@ struct bsc_nat {
/* control interface */
struct ctrl_handle *ctrl;
-
- /* for random values */
- int random_fd;
};
struct bsc_nat_ussd_con {
diff --git a/openbsc/src/osmo-bsc_nat/Makefile.am b/openbsc/src/osmo-bsc_nat/Makefile.am
index d96a391..4a6f74d 100644
--- a/openbsc/src/osmo-bsc_nat/Makefile.am
+++ b/openbsc/src/osmo-bsc_nat/Makefile.am
@@ -1,5 +1,5 @@
AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include -I$(top_builddir)
-AM_CFLAGS=-Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOVTY_CFLAGS) $(LIBOSMOCTRL_CFLAGS) $(LIBOSMOSCCP_CFLAGS) $(LIBOSMOABIS_CFLAGS) $(LIBOSMONETIF_CFLAGS) $(COVERAGE_CFLAGS)
+AM_CFLAGS=-Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOVTY_CFLAGS) $(LIBOSMOCTRL_CFLAGS) $(LIBOSMOSCCP_CFLAGS) $(LIBOSMOABIS_CFLAGS) $(LIBOSMONETIF_CFLAGS) $(LIBCRYPTO_CFLAGS) $(COVERAGE_CFLAGS)
AM_LDFLAGS = $(COVERAGE_LDFLAGS)
bin_PROGRAMS = osmo-bsc_nat
@@ -16,4 +16,4 @@ osmo_bsc_nat_LDADD = \
$(top_builddir)/src/libfilter/libfilter.a \
-lrt $(LIBOSMOSCCP_LIBS) $(LIBOSMOCORE_LIBS) \
$(LIBOSMOGSM_LIBS) $(LIBOSMOVTY_LIBS) $(LIBOSMOCTRL_LIBS) \
- $(LIBOSMOABIS_LIBS) $(LIBOSMONETIF_LIBS)
+ $(LIBOSMOABIS_LIBS) $(LIBOSMONETIF_LIBS) $(LIBCRYPTO_LIBS)
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index 581193e..1fc262d 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat.c
@@ -69,6 +69,8 @@
#include <osmocom/abis/ipa.h>
+#include <openssl/rand.h>
+
#include "../../bscconfig.h"
#define SCCP_CLOSE_TIME 20
@@ -204,8 +206,7 @@ static void send_id_req(struct bsc_nat *nat, struct bsc_connection *bsc)
0x01, IPAC_IDTAG_SERNR,
};
- int toread, rounds;
- uint8_t *mrand, *randoff;
+ uint8_t *mrand;
uint8_t id_req[sizeof(s_id_req) + (2+16)];
uint8_t *buf = &id_req[sizeof(s_id_req)];
@@ -216,19 +217,10 @@ static void send_id_req(struct bsc_nat *nat, struct bsc_connection *bsc)
buf = v_put(buf, 0x11);
buf = v_put(buf, 0x23);
mrand = bsc->last_rand;
- randoff = mrand;
- memset(randoff, 0, 16);
-
- for (toread = 16, rounds = 0; rounds < 5 && toread > 0; ++rounds) {
- int rc = read(nat->random_fd, randoff, toread);
- if (rc <= 0)
- goto failed_random;
- toread -= rc;
- randoff += rc;
- }
- if (toread != 0)
+ if (RAND_bytes(mrand, 16) != 1)
goto failed_random;
+
memcpy(buf, mrand, 16);
buf += 16;
@@ -1628,12 +1620,6 @@ int main(int argc, char **argv)
/* We need to add mode-set for amr codecs */
nat->sdp_ensure_amr_mode_set = 1;
- nat->random_fd = open("/dev/random", O_RDONLY);
- if (nat->random_fd < 0) {
- fprintf(stderr, "Failed to open /dev/urandom.\n");
- return -5;
- }
-
vty_info.copyright = openbsc_copyright;
vty_init(&vty_info);
logging_vty_add_cmds(&log_info);