Use common error logic regardless of setexecfilecon() availability

Refactor the custom exec context setting code to look like setexecfilecon()
in case the real one is not available to eliminate pesky behavioral
differences between the two cases.

This fixes a concrete bug of libselinux setexecfilecon() returning with
an error when security_getenforce() returns with -1 (such as a bare
chroot with no /sys mounts etc), causing us to spit out useless error
messages in that case ever since fixing the bogus if-logic in
commit ab601b8.

Fixes: #1077

plugins/selinux.c

@@ -94,65 +94,63 @@ static rpmRC selinux_psm_pre(rpmPlugin plugin, rpmte te)
     return rc;
 }
 
-static rpmRC selinux_scriptlet_fork_post(rpmPlugin plugin,
-						 const char *path, int type)
-{
-    rpmRC rc = RPMRC_FAIL;
-    int xx;
 #ifndef HAVE_SETEXECFILECON
+static int setexecfilecon(const char *path, const char *fallback_type)
+{
+    int rc = -1;
     security_context_t mycon = NULL, fcon = NULL, newcon = NULL;
     context_t con = NULL;
 
-    if (sehandle == NULL)
-	return RPMRC_OK;
-
     /* Figure the context to for next exec() */
     if (getcon(&mycon) < 0)
 	goto exit;
     if (getfilecon(path, &fcon) < 0)
 	goto exit;
-    if (security_compute_create(mycon, fcon, string_to_security_class("process"), &newcon) < 0)
+    if (security_compute_create(mycon, fcon,
+			string_to_security_class("process"), &newcon) < 0)
 	goto exit;
 
     if (rstreq(mycon, newcon)) {
-	/* No default transition, use rpm_script_t for now. */
-	const char * script_type = "rpm_script_t";
-
 	con = context_new(mycon);
 	if (!con)
 	    goto exit;
-	if (context_type_set(con, script_type))
+	if (context_type_set(con, fallback_type))
 	    goto exit;
 	freecon(newcon);
 	newcon = xstrdup(context_str(con));
     }
 
-    if ((xx = setexeccon(newcon)) == 0)
-	rc = RPMRC_OK;
-
-    rpmlog(loglvl(xx < 0), "setexeccon: (%s, %s) %s\n",
-	       path, newcon, (xx < 0 ? strerror(errno) : ""));
+    rc = setexeccon(newcon);
 
 exit:
     context_free(con);
     freecon(newcon);
     freecon(fcon);
     freecon(mycon);
+    return rc;
+}
+#endif
+
+static rpmRC selinux_scriptlet_fork_post(rpmPlugin plugin,
+						 const char *path, int type)
+{
+    /* No default transition, use rpm_script_t for now. */
+    const char *script_type  = "rpm_script_t";
+    rpmRC rc = RPMRC_FAIL;
 
-#else
     if (sehandle == NULL)
 	return RPMRC_OK;
 
-    if ((xx = setexecfilecon(path, "rpm_script_t")) == 0)
+    if (setexecfilecon(path, script_type) == 0)
 	rc = RPMRC_OK;
 
-    rpmlog(loglvl(xx < 0), "setexecfilecon: (%s) %s\n",
-	       path, (xx < 0 ? strerror(errno) : ""));
-#endif
     /* If selinux is not enforcing, we don't care either */
     if (rc && security_getenforce() < 1)
 	rc = RPMRC_OK;
 
+    rpmlog(loglvl(rc), "setexecfilecon: (%s, %s) %s\n",
+	       path, script_type, rc ? strerror(errno) : "");
+
     return rc;
 }