Add regexp authorization policy for IMSI

* extend "auth policy" vty command with new option "regexp"
* add vty command "authorized-regexp" for setting arbitrary POSIX
  regular expression
* add basic vty test
* add optional "regexp" argument to subscriber-create-on-demand vty
  command

With those in place we can now set the regexp against which MS's IMSI
will be matched.

If IMSI match the regexp than MS is allowed to access the network. If
subscriber is already marked as authorized in HLR than it'll be allowed
regardless of IMSI matching.

The same way we can decide whether to create subscribers on-demand
basesd on IMSI regexp match. Similar to authorization this restriction
can be overridden by manually creating subscriber via vty, ctrl
interface or directly in HLR.

Change-Id: I525f4b80676de47d1d422686da2ca012301b0129
Fixes: OS#1647

openbsc/include/openbsc/gsm_data.h

@@ -2,6 +2,8 @@
 #define _GSM_DATA_H
 
 #include <stdint.h>
+#include <regex.h>
+#include <sys/types.h>
 
 #include <osmocom/core/timer.h>
 #include <osmocom/core/select.h>
@@ -22,6 +24,7 @@ struct gsm_subscriber_group;
 enum gsm_subscr_creation_mode {
 	GSM_SUBSCR_DONT_CREATE = 0,
 	GSM_SUBSCR_CREAT_W_RAND_EXT = 1,
+	GSM_SUBSCR_CREAT_W_REGEXP = 2,
 };
 
 enum gsm_security_event {
@@ -205,6 +208,7 @@ enum gsm_auth_policy {
 	GSM_AUTH_POLICY_CLOSED, /* only subscribers authorized in DB */
 	GSM_AUTH_POLICY_ACCEPT_ALL, /* accept everyone, even if not authorized in DB */
 	GSM_AUTH_POLICY_TOKEN, /* accept first, send token per sms, then revoke authorization */
+	GSM_AUTH_POLICY_REGEXP, /* accept IMSIs matching given regexp */
 };
 
 #define GSM_T3101_DEFAULT 10
@@ -219,6 +223,8 @@ struct gsm_network {
 	char *name_long;
 	char *name_short;
 	enum gsm_auth_policy auth_policy;
+	regex_t authorized_regexp;
+	char *authorized_reg_str;
 	enum gsm48_reject_value reject_cause;
 	int a5_encryption;
 	int neci;

openbsc/src/libbsc/bsc_vty.c

@@ -190,8 +190,11 @@ static void net_dump_vty(struct vty *vty, struct gsm_network *net)
 		net->name_long, VTY_NEWLINE);
 	vty_out(vty, "  Short network name: '%s'%s",
 		net->name_short, VTY_NEWLINE);
-	vty_out(vty, "  Authentication policy: %s%s",
-		gsm_auth_policy_name(net->auth_policy), VTY_NEWLINE);
+	vty_out(vty, "  Authentication policy: %s",
+		gsm_auth_policy_name(net->auth_policy));
+	if (net->authorized_reg_str)
+		vty_out(vty, ", authorized regexp: %s", net->authorized_reg_str);
+	vty_out(vty, "%s", VTY_NEWLINE);
 	vty_out(vty, "  Location updating reject cause: %u%s",
 		net->reject_cause, VTY_NEWLINE);
 	vty_out(vty, "  Encryption: A5/%u%s", net->a5_encryption,
@@ -791,6 +794,8 @@ static int config_write_net(struct vty *vty)
 	vty_out(vty, " short name %s%s", gsmnet->name_short, VTY_NEWLINE);
 	vty_out(vty, " long name %s%s", gsmnet->name_long, VTY_NEWLINE);
 	vty_out(vty, " auth policy %s%s", gsm_auth_policy_name(gsmnet->auth_policy), VTY_NEWLINE);
+	if (gsmnet->authorized_reg_str)
+		vty_out(vty, " authorized-regexp %s%s", gsmnet->authorized_reg_str, VTY_NEWLINE);
 	vty_out(vty, " location updating reject cause %u%s",
 		gsmnet->reject_cause, VTY_NEWLINE);
 	vty_out(vty, " encryption a5 %u%s", gsmnet->a5_encryption, VTY_NEWLINE);
@@ -1398,11 +1403,12 @@ DEFUN(cfg_net_name_long,
 
 DEFUN(cfg_net_auth_policy,
       cfg_net_auth_policy_cmd,
-      "auth policy (closed|accept-all|token)",
+      "auth policy (closed|accept-all|regexp|token)",
 	"Authentication (not cryptographic)\n"
 	"Set the GSM network authentication policy\n"
 	"Require the MS to be activated in HLR\n"
 	"Accept all MS, whether in HLR or not\n"
+	"Use regular expression for IMSI authorization decision\n"
 	"Use SMS-token based authentication\n")
 {
 	enum gsm_auth_policy policy = gsm_auth_policy_parse(argv[0]);
@@ -1413,6 +1419,22 @@ DEFUN(cfg_net_auth_policy,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_net_authorize_regexp, cfg_net_authorize_regexp_cmd,
+      "authorized-regexp REGEXP",
+      "Set regexp for IMSI which will be used for authorization decision\n"
+      "Regular expression, IMSIs matching it are allowed to use the network\n")
+{
+	struct gsm_network *gsmnet = gsmnet_from_vty(vty);
+	if (gsm_parse_reg(gsmnet, &gsmnet->authorized_regexp,
+			  &gsmnet->authorized_reg_str, argc, argv) != 0) {
+		vty_out(vty, "%%Failed to parse the authorized-regexp: '%s'%s",
+			argv[0], VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_net_reject_cause,
       cfg_net_reject_cause_cmd,
       "location updating reject cause <2-111>",
@@ -3973,6 +3995,7 @@ int bsc_vty_init(const struct log_info *cat)
 	install_element(GSMNET_NODE, &cfg_net_name_short_cmd);
 	install_element(GSMNET_NODE, &cfg_net_name_long_cmd);
 	install_element(GSMNET_NODE, &cfg_net_auth_policy_cmd);
+	install_element(GSMNET_NODE, &cfg_net_authorize_regexp_cmd);
 	install_element(GSMNET_NODE, &cfg_net_reject_cause_cmd);
 	install_element(GSMNET_NODE, &cfg_net_encryption_cmd);
 	install_element(GSMNET_NODE, &cfg_net_neci_cmd);

openbsc/src/libcommon/gsm_data.c

@@ -162,6 +162,7 @@ static const struct value_string auth_policy_names[] = {
 	{ GSM_AUTH_POLICY_CLOSED,	"closed" },
 	{ GSM_AUTH_POLICY_ACCEPT_ALL,	"accept-all" },
 	{ GSM_AUTH_POLICY_TOKEN,	"token" },
+	{ GSM_AUTH_POLICY_REGEXP,	"regexp" },
 	{ 0,				NULL }
 };
 

openbsc/src/libmsc/gsm_04_08.c

@@ -25,9 +25,12 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <stdbool.h>
 #include <errno.h>
 #include <time.h>
 #include <netinet/in.h>
+#include <regex.h>
+#include <sys/types.h>
 
 #include "bscconfig.h"
 
@@ -244,6 +247,17 @@ int gsm48_secure_channel(struct gsm_subscriber_connection *conn, int key_seq,
 	return -EINVAL; /* not reached */
 }
 
+static bool subscr_regexp_check(const struct gsm_network *net, const char *imsi)
+{
+	if (!net->authorized_reg_str)
+		return false;
+
+	if (regexec(&net->authorized_regexp, imsi, 0, NULL, 0) != REG_NOMATCH)
+		return true;
+
+	return false;
+}
+
 static int authorize_subscriber(struct gsm_loc_updating_operation *loc,
 				struct gsm_subscriber *subscriber)
 {
@@ -261,6 +275,13 @@ static int authorize_subscriber(struct gsm_loc_updating_operation *loc,
 	switch (subscriber->group->net->auth_policy) {
 	case GSM_AUTH_POLICY_CLOSED:
 		return subscriber->authorized;
+	case GSM_AUTH_POLICY_REGEXP:
+		if (subscriber->authorized)
+			return 1;
+		if (subscr_regexp_check(subscriber->group->net,
+					subscriber->imsi))
+			subscriber->authorized = 1;
+		return subscriber->authorized;
 	case GSM_AUTH_POLICY_TOKEN:
 		if (subscriber->authorized)
 			return subscriber->authorized;
@@ -509,10 +530,14 @@ static int mm_tx_identity_req(struct gsm_subscriber_connection *conn, uint8_t id
 static struct gsm_subscriber *subscr_create(const struct gsm_network *net,
 					    const char *imsi)
 {
-	if (net->subscr_creation_mode != GSM_SUBSCR_DONT_CREATE)
-		return subscr_create_subscriber(net->subscr_group, imsi);
+	if (net->subscr_creation_mode == GSM_SUBSCR_DONT_CREATE)
+		return NULL;
 
-	return NULL;
+	if (net->subscr_creation_mode & GSM_SUBSCR_CREAT_W_REGEXP)
+		if (!subscr_regexp_check(net, imsi))
+			return NULL;
+
+	return subscr_create_subscriber(net->subscr_group, imsi);
 }
 
 /* Parse Chapter 9.2.11 Identity Response */

openbsc/src/libmsc/vty_interface_layer3.c

@@ -1032,11 +1032,15 @@ DEFUN(cfg_nitb, cfg_nitb_cmd,
 }
 
 DEFUN(cfg_nitb_subscr_create, cfg_nitb_subscr_create_cmd,
-      "subscriber-create-on-demand",
-      "Make a new record when a subscriber is first seen.\n")
+      "subscriber-create-on-demand [regexp]",
+      "Make a new record when a subscriber is first seen.\n"
+      "Create subscribers only if IMSI matches the regexp specified in "
+      "authorized-regexp command\n")
 {
 	struct gsm_network *gsmnet = gsmnet_from_vty(vty);
 	gsmnet->subscr_creation_mode = GSM_SUBSCR_CREAT_W_RAND_EXT;
+	if (argc)
+		gsmnet->subscr_creation_mode |= GSM_SUBSCR_CREAT_W_REGEXP;
 	return CMD_SUCCESS;
 }
 
@@ -1070,9 +1074,12 @@ DEFUN(cfg_nitb_no_assign_tmsi, cfg_nitb_no_assign_tmsi_cmd,
 static int config_write_nitb(struct vty *vty)
 {
 	struct gsm_network *gsmnet = gsmnet_from_vty(vty);
+	enum gsm_subscr_creation_mode scm = gsmnet->subscr_creation_mode;
+	const char *reg = (scm & GSM_SUBSCR_CREAT_W_REGEXP) ? " regexp" : "",
+		*pref = scm ? "" : "no ";
 	vty_out(vty, "nitb%s", VTY_NEWLINE);
-	vty_out(vty, " %ssubscriber-create-on-demand%s",
-		gsmnet->subscr_creation_mode ? "" : "no ", VTY_NEWLINE);
+	vty_out(vty, " %ssubscriber-create-on-demand%s%s",
+		pref, reg, VTY_NEWLINE);
 	vty_out(vty, " %sassign-tmsi%s",
 		gsmnet->avoid_tmsi ? "no " : "", VTY_NEWLINE);
 	return CMD_SUCCESS;

openbsc/tests/vty_test_runner.py

@@ -231,6 +231,22 @@ class TestVTYNITB(TestVTYGenericBSC):
 
         self.assertEquals(self.vty.node(), 'config-mncc-int')
 
+    def testVtyAuthorization(self):
+        self.vty.enable()
+        self.vty.command("configure terminal")
+        self.vty.command("network")
+        self.assertTrue(self.vty.verify("auth policy closed", ['']))
+        self.assertTrue(self.vty.verify("auth policy regexp", ['']))
+        self.assertTrue(self.vty.verify("authorized-regexp ^001", ['']))
+        self.assertTrue(self.vty.verify("authorized-regexp 02$", ['']))
+        self.assertTrue(self.vty.verify("authorized-regexp *123.*", ['']))
+        self.vty.command("end")
+        self.vty.command("configure terminal")
+        self.vty.command("nitb")
+        self.assertTrue(self.vty.verify("subscriber-create-on-demand", ['']))
+        self.assertTrue(self.vty.verify("subscriber-create-on-demand regexp", ['']))
+        self.vty.command("end")
+
     def testSi2Q(self):
         self.vty.enable()
         self.vty.command("configure terminal")