voice: validate outgoing and deflect call numbers

Validate the number parameter in Voice.CreateCall and Call.Deflect
D-Bus methods to ensure they do not contain control characters or
semicolons. This prevents AT command injection when the number is
later spliced into ATD or +CTFR commands.

Introduce a common helper mm_utils_is_valid_dial_number() to validate
dial numbers, and add unit tests for it.

https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/work_items/1067

Signed-off-by: Aleksander Morgado <aleksandermj@google.com>

src/mm-base-call.c

@@ -440,6 +440,13 @@ handle_deflect_auth_ready (MMAuthProvider       *authp,
         return;
     }
 
+    /* Validate input number */
+    if (!mm_utils_is_valid_dial_number (ctx->number, &error)) {
+        mm_dbus_method_invocation_take_error (ctx->invocation, error);
+        handle_deflect_context_free (ctx);
+        return;
+    }
+
     state = mm_gdbus_call_get_state (MM_GDBUS_CALL (ctx->self));
 
     /* We can only deflect incoming call in ringing or waiting state */

src/mm-iface-modem-voice.c

@@ -23,6 +23,7 @@
 #include "mm-call-list.h"
 #include "mm-error-helpers.h"
 #include "mm-log-object.h"
+#include "mm-modem-helpers.h"
 
 #define CALL_LIST_POLLING_CONTEXT_TAG "voice-call-list-polling-context-tag"
 #define IN_CALL_EVENT_CONTEXT_TAG     "voice-in-call-event-context-tag"
@@ -176,14 +177,9 @@ create_outgoing_call_from_properties (MMIfaceModemVoice  *self,
     guint        dtmf_tone_duration;
 
     /* Don't create CALL from properties if either number is missing */
-    number = mm_call_properties_get_number (properties) ;
-    if (!number) {
-        g_set_error (error,
-                     MM_CORE_ERROR,
-                     MM_CORE_ERROR_INVALID_ARGS,
-                     "Cannot create call: mandatory parameter 'number' is missing");
+    number = mm_call_properties_get_number (properties);
+    if (!mm_utils_is_valid_dial_number (number, error))
         return NULL;
-    }
 
     dtmf_tone_duration = mm_call_properties_get_dtmf_tone_duration (properties) ;
 

src/mm-modem-helpers.c

@@ -5992,3 +5992,25 @@ mm_utils_is_numeric (const gchar *str)
     }
     return TRUE;
 }
+
+gboolean
+mm_utils_is_valid_dial_number (const gchar  *str,
+                               GError      **error)
+{
+    const gchar *c;
+
+    if (!str || !str[0]) {
+        g_set_error_literal (error, MM_CORE_ERROR, MM_CORE_ERROR_INVALID_ARGS,
+                             "missing number");
+        return FALSE;
+    }
+
+    for (c = str; *c; c++) {
+        if (((guint8)*c) < 0x20 || *c == ';') {
+            g_set_error (error, MM_CORE_ERROR, MM_CORE_ERROR_INVALID_ARGS,
+                         "invalid character '0x%02x' in number", (guint8)*c);
+            return FALSE;
+        }
+    }
+    return TRUE;
+}

src/mm-modem-helpers.h

@@ -574,6 +574,8 @@ gboolean mm_parse_supl_address (const gchar  *supl,
 void mm_utils_remove_control_characters (gchar *str);
 gboolean mm_utils_is_valid_fqdn (const gchar *fqdn);
 gboolean mm_utils_is_numeric (const gchar *str);
+gboolean mm_utils_is_valid_dial_number (const gchar  *str,
+                                        GError      **error);
 
 gboolean mm_validate_cbs_channels (GArray   *channels,
                                    GError  **error);

src/tests/test-modem-helpers.c

@@ -4923,6 +4923,63 @@ test_is_numeric (void *f, gpointer d)
     g_assert (!mm_utils_is_numeric ("+123"));
 }
 
+static void
+test_is_valid_dial_number (void *f, gpointer d)
+{
+    GError   *error = NULL;
+    gboolean  r;
+
+    r = mm_utils_is_valid_dial_number ("123456", &error);
+    g_assert (r);
+    g_assert_no_error (error);
+
+    r = mm_utils_is_valid_dial_number ("+123456", &error);
+    g_assert (r);
+    g_assert_no_error (error);
+
+    r = mm_utils_is_valid_dial_number ("*123#", &error);
+    g_assert (r);
+    g_assert_no_error (error);
+
+    r = mm_utils_is_valid_dial_number ("123,456", &error);
+    g_assert (r);
+    g_assert_no_error (error);
+
+    r = mm_utils_is_valid_dial_number ("123W456", &error);
+    g_assert (r);
+    g_assert_no_error (error);
+
+    r = mm_utils_is_valid_dial_number (NULL, &error);
+    g_assert (!r);
+    g_assert_error (error, MM_CORE_ERROR, MM_CORE_ERROR_INVALID_ARGS);
+    g_clear_error (&error);
+
+    r = mm_utils_is_valid_dial_number ("", &error);
+    g_assert (!r);
+    g_assert_error (error, MM_CORE_ERROR, MM_CORE_ERROR_INVALID_ARGS);
+    g_clear_error (&error);
+
+    r = mm_utils_is_valid_dial_number ("123;456", &error);
+    g_assert (!r);
+    g_assert_error (error, MM_CORE_ERROR, MM_CORE_ERROR_INVALID_ARGS);
+    g_clear_error (&error);
+
+    r = mm_utils_is_valid_dial_number ("123\r456", &error);
+    g_assert (!r);
+    g_assert_error (error, MM_CORE_ERROR, MM_CORE_ERROR_INVALID_ARGS);
+    g_clear_error (&error);
+
+    r = mm_utils_is_valid_dial_number ("123\n456", &error);
+    g_assert (!r);
+    g_assert_error (error, MM_CORE_ERROR, MM_CORE_ERROR_INVALID_ARGS);
+    g_clear_error (&error);
+
+    r = mm_utils_is_valid_dial_number ("123\x01" "456", &error);
+    g_assert (!r);
+    g_assert_error (error, MM_CORE_ERROR, MM_CORE_ERROR_INVALID_ARGS);
+    g_clear_error (&error);
+}
+
 /*****************************************************************************/
 
 typedef struct {
@@ -5472,6 +5529,7 @@ int main (int argc, char **argv)
     g_test_suite_add (suite, TESTCASE (test_remove_control_characters, NULL));
     g_test_suite_add (suite, TESTCASE (test_is_valid_fqdn, NULL));
     g_test_suite_add (suite, TESTCASE (test_is_numeric, NULL));
+    g_test_suite_add (suite, TESTCASE (test_is_valid_dial_number, NULL));
 
     g_test_suite_add (suite, TESTCASE (test_cpol_response, NULL));