/* sets obj->mod if object is not vmlinux and module is found */
static void klp_find_object_module(struct klp_object *obj)
{
+ struct module *mod;
+
if (!klp_is_module(obj))
return;
mutex_lock(&module_mutex);
/*
- * We don't need to take a reference on the module here because we have
- * the klp_mutex, which is also taken by the module notifier. This
- * prevents any module from unloading until we release the klp_mutex.
+ * We do not want to block removal of patched modules and therefore
+ * we do not take a reference here. The patches are removed by
+ * a going module handler instead.
+ */
+ mod = find_module(obj->name);
+ /*
+ * Do not mess work of the module coming and going notifiers.
+ * Note that the patch might still be needed before the going handler
+ * is called. Module functions can be called even in the GOING state
+ * until mod->exit() finishes. This is especially important for
+ * patches that modify semantic of the functions.
*/
- obj->mod = find_module(obj->name);
+ if (mod && mod->klp_alive)
+ obj->mod = mod;
+
mutex_unlock(&module_mutex);
}
static bool klp_initialized(void)
{
- return klp_root_kobj;
+ return !!klp_root_kobj;
}
struct klp_find_arg {
/* first, check if it's an exported symbol */
preempt_disable();
sym = find_symbol(name, NULL, NULL, true, true);
- preempt_enable();
if (sym) {
*addr = sym->value;
+ preempt_enable();
return 0;
}
+ preempt_enable();
/* otherwise check if it's in another .o within the patch module */
return klp_find_object_symbol(pmod->name, name, addr);
rcu_read_lock();
func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
stack_node);
- rcu_read_unlock();
-
if (WARN_ON_ONCE(!func))
- return;
+ goto unlock;
klp_arch_set_pc(regs, (unsigned long)func->new_func);
+unlock:
+ rcu_read_unlock();
}
-static int klp_disable_func(struct klp_func *func)
+static void klp_disable_func(struct klp_func *func)
{
struct klp_ops *ops;
- int ret;
- if (WARN_ON(func->state != KLP_ENABLED))
- return -EINVAL;
-
- if (WARN_ON(!func->old_addr))
- return -EINVAL;
+ WARN_ON(func->state != KLP_ENABLED);
+ WARN_ON(!func->old_addr);
ops = klp_find_ops(func->old_addr);
if (WARN_ON(!ops))
- return -EINVAL;
+ return;
if (list_is_singular(&ops->func_stack)) {
- ret = unregister_ftrace_function(&ops->fops);
- if (ret) {
- pr_err("failed to unregister ftrace handler for function '%s' (%d)\n",
- func->old_name, ret);
- return ret;
- }
-
- ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0);
- if (ret)
- pr_warn("function unregister succeeded but failed to clear the filter\n");
+ WARN_ON(unregister_ftrace_function(&ops->fops));
+ WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0));
list_del_rcu(&func->stack_node);
list_del(&ops->node);
}
func->state = KLP_DISABLED;
-
- return 0;
}
static int klp_enable_func(struct klp_func *func)
return ret;
}
-static int klp_disable_object(struct klp_object *obj)
+static void klp_disable_object(struct klp_object *obj)
{
struct klp_func *func;
- int ret;
- for (func = obj->funcs; func->old_name; func++) {
- if (func->state != KLP_ENABLED)
- continue;
-
- ret = klp_disable_func(func);
- if (ret)
- return ret;
- }
+ for (func = obj->funcs; func->old_name; func++)
+ if (func->state == KLP_ENABLED)
+ klp_disable_func(func);
obj->state = KLP_DISABLED;
-
- return 0;
}
static int klp_enable_object(struct klp_object *obj)
for (func = obj->funcs; func->old_name; func++) {
ret = klp_enable_func(func);
- if (ret)
- goto unregister;
+ if (ret) {
+ klp_disable_object(obj);
+ return ret;
+ }
}
obj->state = KLP_ENABLED;
return 0;
-
-unregister:
- WARN_ON(klp_disable_object(obj));
- return ret;
}
static int __klp_disable_patch(struct klp_patch *patch)
{
struct klp_object *obj;
- int ret;
/* enforce stacking: only the last enabled patch can be disabled */
if (!list_is_last(&patch->list, &klp_patches) &&
pr_notice("disabling patch '%s'\n", patch->mod->name);
for (obj = patch->objs; obj->funcs; obj++) {
- if (obj->state != KLP_ENABLED)
- continue;
-
- ret = klp_disable_object(obj);
- if (ret)
- return ret;
+ if (obj->state == KLP_ENABLED)
+ klp_disable_object(obj);
}
patch->state = KLP_DISABLED;
pr_notice("enabling patch '%s'\n", patch->mod->name);
for (obj = patch->objs; obj->funcs; obj++) {
- klp_find_object_module(obj);
-
if (!klp_is_object_loaded(obj))
continue;
func->state = KLP_DISABLED;
return kobject_init_and_add(&func->kobj, &klp_ktype_func,
- obj->kobj, func->old_name);
+ obj->kobj, "%s", func->old_name);
}
/* parts of the initialization that is done only when the object is loaded */
return -EINVAL;
obj->state = KLP_DISABLED;
+ obj->mod = NULL;
klp_find_object_module(obj);
patch->state = KLP_DISABLED;
ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch,
- klp_root_kobj, patch->mod->name);
+ klp_root_kobj, "%s", patch->mod->name);
if (ret)
goto unlock;
}
EXPORT_SYMBOL_GPL(klp_register_patch);
-static void klp_module_notify_coming(struct klp_patch *patch,
+static int klp_module_notify_coming(struct klp_patch *patch,
struct klp_object *obj)
{
struct module *pmod = patch->mod;
int ret;
ret = klp_init_object_loaded(patch, obj);
- if (ret)
- goto err;
+ if (ret) {
+ pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
+ pmod->name, mod->name, ret);
+ return ret;
+ }
if (patch->state == KLP_DISABLED)
- return;
+ return 0;
pr_notice("applying patch '%s' to loading module '%s'\n",
pmod->name, mod->name);
ret = klp_enable_object(obj);
- if (!ret)
- return;
-
-err:
- pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
- pmod->name, mod->name, ret);
+ if (ret)
+ pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
+ pmod->name, mod->name, ret);
+ return ret;
}
static void klp_module_notify_going(struct klp_patch *patch,
{
struct module *pmod = patch->mod;
struct module *mod = obj->mod;
- int ret;
if (patch->state == KLP_DISABLED)
goto disabled;
pr_notice("reverting patch '%s' on unloading module '%s'\n",
pmod->name, mod->name);
- ret = klp_disable_object(obj);
- if (ret)
- pr_warn("failed to revert patch '%s' on module '%s' (%d)\n",
- pmod->name, mod->name, ret);
+ klp_disable_object(obj);
disabled:
klp_free_object_loaded(obj);
static int klp_module_notify(struct notifier_block *nb, unsigned long action,
void *data)
{
+ int ret;
struct module *mod = data;
struct klp_patch *patch;
struct klp_object *obj;
mutex_lock(&klp_mutex);
+ /*
+ * Each module has to know that the notifier has been called.
+ * We never know what module will get patched by a new patch.
+ */
+ if (action == MODULE_STATE_COMING)
+ mod->klp_alive = true;
+ else /* MODULE_STATE_GOING */
+ mod->klp_alive = false;
+
list_for_each_entry(patch, &klp_patches, list) {
for (obj = patch->objs; obj->funcs; obj++) {
if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
if (action == MODULE_STATE_COMING) {
obj->mod = mod;
- klp_module_notify_coming(patch, obj);
+ ret = klp_module_notify_coming(patch, obj);
+ if (ret) {
+ obj->mod = NULL;
+ pr_warn("patch '%s' is in an inconsistent state!\n",
+ patch->mod->name);
+ }
} else /* MODULE_STATE_GOING */
klp_module_notify_going(patch, obj);
projects / deliverable / linux.git / blobdiff