livepatch: add (un)patch callbacks
Provide livepatch modules a klp_object (un)patching notification
mechanism. Pre and post-(un)patch callbacks allow livepatch modules to
setup or synchronize changes that would be difficult to support in only
patched-or-unpatched code contexts.
Callbacks can be registered for target module or vmlinux klp_objects,
but each implementation is klp_object specific.
- Pre-(un)patch callbacks run before any (un)patching transition
starts.
- Post-(un)patch callbacks run once an object has been (un)patched and
the klp_patch fully transitioned to its target state.
Example use cases include modification of global data and registration
of newly available services/handlers.
See Documentation/livepatch/callbacks.txt for details and
samples/livepatch/ for examples.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index b9628e4..cafb5a8 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -54,11 +54,6 @@
return obj->name;
}
-static bool klp_is_object_loaded(struct klp_object *obj)
-{
- return !obj->name || obj->mod;
-}
-
/* sets obj->mod if object is not vmlinux and module is found */
static void klp_find_object_module(struct klp_object *obj)
{
@@ -285,6 +280,8 @@
static int __klp_disable_patch(struct klp_patch *patch)
{
+ struct klp_object *obj;
+
if (klp_transition_patch)
return -EBUSY;
@@ -295,6 +292,10 @@
klp_init_transition(patch, KLP_UNPATCHED);
+ klp_for_each_object(patch, obj)
+ if (patch->enabled && obj->patched)
+ klp_pre_unpatch_callback(obj);
+
/*
* Enforce the order of the func->transition writes in
* klp_init_transition() and the TIF_PATCH_PENDING writes in
@@ -388,13 +389,18 @@
if (!klp_is_object_loaded(obj))
continue;
+ ret = klp_pre_patch_callback(obj);
+ if (ret) {
+ pr_warn("pre-patch callback failed for object '%s'\n",
+ klp_is_module(obj) ? obj->name : "vmlinux");
+ goto err;
+ }
+
ret = klp_patch_object(obj);
if (ret) {
- pr_warn("failed to enable patch '%s'\n",
- patch->mod->name);
-
- klp_cancel_transition();
- return ret;
+ pr_warn("failed to patch object '%s'\n",
+ klp_is_module(obj) ? obj->name : "vmlinux");
+ goto err;
}
}
@@ -403,6 +409,11 @@
patch->enabled = true;
return 0;
+err:
+ pr_warn("failed to enable patch '%s'\n", patch->mod->name);
+
+ klp_cancel_transition();
+ return ret;
}
/**
@@ -871,13 +882,27 @@
pr_notice("applying patch '%s' to loading module '%s'\n",
patch->mod->name, obj->mod->name);
+ ret = klp_pre_patch_callback(obj);
+ if (ret) {
+ pr_warn("pre-patch callback failed for object '%s'\n",
+ obj->name);
+ goto err;
+ }
+
ret = klp_patch_object(obj);
if (ret) {
pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
patch->mod->name, obj->mod->name, ret);
+
+ if (patch != klp_transition_patch)
+ klp_post_unpatch_callback(obj);
+
goto err;
}
+ if (patch != klp_transition_patch)
+ klp_post_patch_callback(obj);
+
break;
}
}
@@ -927,9 +952,15 @@
* is in transition.
*/
if (patch->enabled || patch == klp_transition_patch) {
+
+ if (patch != klp_transition_patch)
+ klp_pre_unpatch_callback(obj);
+
pr_notice("reverting patch '%s' on unloading module '%s'\n",
patch->mod->name, obj->mod->name);
klp_unpatch_object(obj);
+
+ klp_post_unpatch_callback(obj);
}
klp_free_object_loaded(obj);