* @old_size: size of the old function
* @new_size: size of the new function
* @kobj_added: @kobj has been added and needs freeing
+ * @nop: temporary patch to use the original code again; dyn. allocated
* @patched: the func has been added to the klp_ops list
* @transition: the func is currently being applied or reverted
*
struct list_head stack_node;
unsigned long old_size, new_size;
bool kobj_added;
+ bool nop;
bool patched;
bool transition;
};
* @mod: kernel module associated with the patched object
* (NULL for vmlinux)
* @kobj_added: @kobj has been added and needs freeing
+ * @dynamic: temporary object for nop functions; dynamically allocated
* @patched: the object's funcs have been added to the klp_ops list
*/
struct klp_object {
struct list_head node;
struct module *mod;
bool kobj_added;
+ bool dynamic;
bool patched;
};
* struct klp_patch - patch structure for live patching
* @mod: reference to the live patch module
* @objs: object entries for kernel objects to be patched
+ * @replace: replace all actively used patches
* @list: list node for global list of actively used patches
* @kobj: kobject for sysfs resources
* @obj_list: dynamic list of the object entries
/* external */
struct module *mod;
struct klp_object *objs;
+ bool replace;
/* internal */
struct list_head list;
#define klp_for_each_object_static(patch, obj) \
for (obj = patch->objs; obj->funcs || obj->name; obj++)
+#define klp_for_each_object_safe(patch, obj, tmp_obj) \
+ list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node)
+
#define klp_for_each_object(patch, obj) \
list_for_each_entry(obj, &patch->obj_list, node)
func->old_name || func->new_func || func->old_sympos; \
func++)
+#define klp_for_each_func_safe(obj, func, tmp_func) \
+ list_for_each_entry_safe(func, tmp_func, &obj->func_list, node)
+
#define klp_for_each_func(obj, func) \
list_for_each_entry(func, &obj->func_list, node)
return !!klp_root_kobj;
}
+static struct klp_func *klp_find_func(struct klp_object *obj,
+ struct klp_func *old_func)
+{
+ struct klp_func *func;
+
+ klp_for_each_func(obj, func) {
+ if ((strcmp(old_func->old_name, func->old_name) == 0) &&
+ (old_func->old_sympos == func->old_sympos)) {
+ return func;
+ }
+ }
+
+ return NULL;
+}
+
+static struct klp_object *klp_find_object(struct klp_patch *patch,
+ struct klp_object *old_obj)
+{
+ struct klp_object *obj;
+
+ klp_for_each_object(patch, obj) {
+ if (klp_is_module(old_obj)) {
+ if (klp_is_module(obj) &&
+ strcmp(old_obj->name, obj->name) == 0) {
+ return obj;
+ }
+ } else if (!klp_is_module(obj)) {
+ return obj;
+ }
+ }
+
+ return NULL;
+}
+
struct klp_find_arg {
const char *objname;
const char *name;
NULL
};
+static void klp_free_object_dynamic(struct klp_object *obj)
+{
+ kfree(obj->name);
+ kfree(obj);
+}
+
+static struct klp_object *klp_alloc_object_dynamic(const char *name)
+{
+ struct klp_object *obj;
+
+ obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+ if (!obj)
+ return NULL;
+
+ if (name) {
+ obj->name = kstrdup(name, GFP_KERNEL);
+ if (!obj->name) {
+ kfree(obj);
+ return NULL;
+ }
+ }
+
+ INIT_LIST_HEAD(&obj->func_list);
+ obj->dynamic = true;
+
+ return obj;
+}
+
+static void klp_free_func_nop(struct klp_func *func)
+{
+ kfree(func->old_name);
+ kfree(func);
+}
+
+static struct klp_func *klp_alloc_func_nop(struct klp_func *old_func,
+ struct klp_object *obj)
+{
+ struct klp_func *func;
+
+ func = kzalloc(sizeof(*func), GFP_KERNEL);
+ if (!func)
+ return NULL;
+
+ if (old_func->old_name) {
+ func->old_name = kstrdup(old_func->old_name, GFP_KERNEL);
+ if (!func->old_name) {
+ kfree(func);
+ return NULL;
+ }
+ }
+
+ /*
+ * func->new_func is same as func->old_func. These addresses are
+ * set when the object is loaded, see klp_init_object_loaded().
+ */
+ func->old_sympos = old_func->old_sympos;
+ func->nop = true;
+
+ return func;
+}
+
+static int klp_add_object_nops(struct klp_patch *patch,
+ struct klp_object *old_obj)
+{
+ struct klp_object *obj;
+ struct klp_func *func, *old_func;
+
+ obj = klp_find_object(patch, old_obj);
+
+ if (!obj) {
+ obj = klp_alloc_object_dynamic(old_obj->name);
+ if (!obj)
+ return -ENOMEM;
+
+ list_add_tail(&obj->node, &patch->obj_list);
+ }
+
+ klp_for_each_func(old_obj, old_func) {
+ func = klp_find_func(obj, old_func);
+ if (func)
+ continue;
+
+ func = klp_alloc_func_nop(old_func, obj);
+ if (!func)
+ return -ENOMEM;
+
+ list_add_tail(&func->node, &obj->func_list);
+ }
+
+ return 0;
+}
+
+/*
+ * Add 'nop' functions which simply return to the caller to run
+ * the original function. The 'nop' functions are added to a
+ * patch to facilitate a 'replace' mode.
+ */
+static int klp_add_nops(struct klp_patch *patch)
+{
+ struct klp_patch *old_patch;
+ struct klp_object *old_obj;
+
+ list_for_each_entry(old_patch, &klp_patches, list) {
+ klp_for_each_object(old_patch, old_obj) {
+ int err;
+
+ err = klp_add_object_nops(patch, old_obj);
+ if (err)
+ return err;
+ }
+ }
+
+ return 0;
+}
+
static void klp_kobj_release_patch(struct kobject *kobj)
{
struct klp_patch *patch;
static void klp_kobj_release_object(struct kobject *kobj)
{
+ struct klp_object *obj;
+
+ obj = container_of(kobj, struct klp_object, kobj);
+
+ if (obj->dynamic)
+ klp_free_object_dynamic(obj);
}
static struct kobj_type klp_ktype_object = {
static void klp_kobj_release_func(struct kobject *kobj)
{
+ struct klp_func *func;
+
+ func = container_of(kobj, struct klp_func, kobj);
+
+ if (func->nop)
+ klp_free_func_nop(func);
}
static struct kobj_type klp_ktype_func = {
static void klp_free_funcs(struct klp_object *obj)
{
- struct klp_func *func;
+ struct klp_func *func, *tmp_func;
- klp_for_each_func(obj, func) {
+ klp_for_each_func_safe(obj, func, tmp_func) {
/* Might be called from klp_init_patch() error path. */
- if (func->kobj_added)
+ if (func->kobj_added) {
kobject_put(&func->kobj);
+ } else if (func->nop) {
+ klp_free_func_nop(func);
+ }
}
}
obj->mod = NULL;
- klp_for_each_func(obj, func)
+ klp_for_each_func(obj, func) {
func->old_func = NULL;
+
+ if (func->nop)
+ func->new_func = NULL;
+ }
}
static void klp_free_objects(struct klp_patch *patch)
{
- struct klp_object *obj;
+ struct klp_object *obj, *tmp_obj;
- klp_for_each_object(patch, obj) {
+ klp_for_each_object_safe(patch, obj, tmp_obj) {
klp_free_funcs(obj);
/* Might be called from klp_init_patch() error path. */
- if (obj->kobj_added)
+ if (obj->kobj_added) {
kobject_put(&obj->kobj);
+ } else if (obj->dynamic) {
+ klp_free_object_dynamic(obj);
+ }
}
}
{
int ret;
- if (!func->old_name || !func->new_func)
+ if (!func->old_name)
+ return -EINVAL;
+
+ /*
+ * NOPs get the address later. The patched module must be loaded,
+ * see klp_init_object_loaded().
+ */
+ if (!func->new_func && !func->nop)
return -EINVAL;
if (strlen(func->old_name) >= KSYM_NAME_LEN)
return -ENOENT;
}
+ if (func->nop)
+ func->new_func = func->old_func;
+
ret = kallsyms_lookup_size_offset((unsigned long)func->new_func,
&func->new_size, NULL);
if (!ret) {
return ret;
patch->kobj_added = true;
+ if (patch->replace) {
+ ret = klp_add_nops(patch);
+ if (ret)
+ return ret;
+ }
+
klp_for_each_object(patch, obj) {
ret = klp_init_object(patch, obj);
if (ret)
}
EXPORT_SYMBOL_GPL(klp_enable_patch);
+/*
+ * This function removes replaced patches.
+ *
+ * We could be pretty aggressive here. It is called in the situation where
+ * these structures are no longer accessible. All functions are redirected
+ * by the klp_transition_patch. They use either a new code or they are in
+ * the original code because of the special nop function patches.
+ *
+ * The only exception is when the transition was forced. In this case,
+ * klp_ftrace_handler() might still see the replaced patch on the stack.
+ * Fortunately, it is carefully designed to work with removed functions
+ * thanks to RCU. We only have to keep the patches on the system. Also
+ * this is handled transparently by patch->module_put.
+ */
+void klp_discard_replaced_patches(struct klp_patch *new_patch)
+{
+ struct klp_patch *old_patch, *tmp_patch;
+
+ list_for_each_entry_safe(old_patch, tmp_patch, &klp_patches, list) {
+ if (old_patch == new_patch)
+ return;
+
+ old_patch->enabled = false;
+ klp_unpatch_objects(old_patch);
+ klp_free_patch_start(old_patch);
+ schedule_work(&old_patch->free_work);
+ }
+}
+
/*
* Remove parts of patches that touch a given kernel module. The list of
* patches processed might be limited. When limit is NULL, all patches
projects / users / willy / linux.git / commitdiff