afb-api-so-v2: Monitor the preinit to catch SEGV

Add monitoring of preinitialisation of bindings v2
in the hope to better handle arbitrary code execution.

Change-Id: I86354caedb17ef9d4904c1f4f47b1ea3c6dd4c40
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

diff --git a/src/afb-api-so-v2.c b/src/afb-api-so-v2.c
index a13c00e..6c98ce4 100644 (file)
--- a/src/afb-api-so-v2.c
+++ b/src/afb-api-so-v2.c
@@ -22,6 +22,7 @@
 #include <dlfcn.h>
 #include <assert.h>
 #include <stdarg.h>
+#include <errno.h>
 
 #include <json-c/json.h>
 #include <afb/afb-binding-v2.h>
@@ -35,6 +36,7 @@
 #include "afb-context.h"
 #include "afb-api-so.h"
 #include "afb-xreq.h"
+#include "sig-monitor.h"
 #include "verbose.h"
 
 /*
@@ -43,6 +45,12 @@
 static const char afb_api_so_v2_descriptor[] = "afbBindingV2";
 static const char afb_api_so_v2_data[] = "afbBindingV2data";
 
+struct preinit
+{
+       int return_code;
+       const struct afb_binding_v2 *binding;
+};
+
 static const struct afb_verb_v2 *search(const struct afb_binding_v2 *binding, const char *name)
 {
        const struct afb_verb_v2 *verb;
@@ -110,10 +118,23 @@ struct json_object *afb_api_so_v2_make_description_openAPIv3(const struct afb_bi
        return r;
 }
 
+static void do_preinit(int sig, void *closure)
+{
+       struct preinit *preinit = closure;
+
+       if (!sig)
+               preinit->return_code = preinit->binding->preinit();
+       else {
+               errno = EINTR;
+               preinit->return_code = -1;
+       }
+};
+
 int afb_api_so_v2_add_binding(const struct afb_binding_v2 *binding, void *handle, struct afb_apiset *declare_set, struct afb_apiset * call_set, struct afb_binding_data_v2 *data)
 {
        int rc;
        struct afb_export *export;
+       struct preinit preinit;
 
        /* basic checks */
        assert(binding);
@@ -136,7 +157,9 @@ int afb_api_so_v2_add_binding(const struct afb_binding_v2 *binding, void *handle
        /* init the binding */
        if (binding->preinit) {
                INFO("binding %s calling preinit function", binding->api);
-               rc = binding->preinit();
+               preinit.binding = binding;
+               sig_monitor(0, do_preinit, &preinit);
+               rc = preinit.return_code;
                if (rc < 0) {
                        ERROR("binding %s preinit function failed...", afb_export_apiname(export));
                        afb_export_undeclare(export);