257 lines
8.2 KiB
C
257 lines
8.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* livepatch.h - Kernel Live Patching Core
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*
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* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
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* Copyright (C) 2014 SUSE
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*/
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#ifndef _LINUX_LIVEPATCH_H_
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#define _LINUX_LIVEPATCH_H_
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#include <linux/module.h>
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#include <linux/ftrace.h>
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#include <linux/completion.h>
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#include <linux/list.h>
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#if IS_ENABLED(CONFIG_LIVEPATCH)
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/* task patch states */
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#define KLP_UNDEFINED -1
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#define KLP_UNPATCHED 0
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#define KLP_PATCHED 1
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/**
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* struct klp_func - function structure for live patching
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* @old_name: name of the function to be patched
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* @new_func: pointer to the patched function code
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* @old_sympos: a hint indicating which symbol position the old function
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* can be found (optional)
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* @old_func: pointer to the function being patched
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* @kobj: kobject for sysfs resources
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* @node: list node for klp_object func_list
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* @stack_node: list node for klp_ops func_stack list
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* @old_size: size of the old function
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* @new_size: size of the new function
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* @nop: temporary patch to use the original code again; dyn. allocated
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* @patched: the func has been added to the klp_ops list
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* @transition: the func is currently being applied or reverted
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*
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* The patched and transition variables define the func's patching state. When
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* patching, a func is always in one of the following states:
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*
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* patched=0 transition=0: unpatched
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* patched=0 transition=1: unpatched, temporary starting state
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* patched=1 transition=1: patched, may be visible to some tasks
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* patched=1 transition=0: patched, visible to all tasks
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*
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* And when unpatching, it goes in the reverse order:
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*
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* patched=1 transition=0: patched, visible to all tasks
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* patched=1 transition=1: patched, may be visible to some tasks
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* patched=0 transition=1: unpatched, temporary ending state
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* patched=0 transition=0: unpatched
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*/
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struct klp_func {
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/* external */
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const char *old_name;
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void *new_func;
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/*
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* The old_sympos field is optional and can be used to resolve
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* duplicate symbol names in livepatch objects. If this field is zero,
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* it is expected the symbol is unique, otherwise patching fails. If
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* this value is greater than zero then that occurrence of the symbol
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* in kallsyms for the given object is used.
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*/
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unsigned long old_sympos;
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/* internal */
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void *old_func;
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struct kobject kobj;
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struct list_head node;
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struct list_head stack_node;
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unsigned long old_size, new_size;
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bool nop;
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bool patched;
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bool transition;
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};
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struct klp_object;
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/**
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* struct klp_callbacks - pre/post live-(un)patch callback structure
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* @pre_patch: executed before code patching
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* @post_patch: executed after code patching
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* @pre_unpatch: executed before code unpatching
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* @post_unpatch: executed after code unpatching
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* @post_unpatch_enabled: flag indicating if post-unpatch callback
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* should run
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*
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* All callbacks are optional. Only the pre-patch callback, if provided,
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* will be unconditionally executed. If the parent klp_object fails to
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* patch for any reason, including a non-zero error status returned from
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* the pre-patch callback, no further callbacks will be executed.
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*/
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struct klp_callbacks {
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int (*pre_patch)(struct klp_object *obj);
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void (*post_patch)(struct klp_object *obj);
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void (*pre_unpatch)(struct klp_object *obj);
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void (*post_unpatch)(struct klp_object *obj);
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bool post_unpatch_enabled;
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};
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/**
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* struct klp_object - kernel object structure for live patching
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* @name: module name (or NULL for vmlinux)
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* @funcs: function entries for functions to be patched in the object
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* @callbacks: functions to be executed pre/post (un)patching
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* @kobj: kobject for sysfs resources
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* @func_list: dynamic list of the function entries
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* @node: list node for klp_patch obj_list
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* @mod: kernel module associated with the patched object
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* (NULL for vmlinux)
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* @dynamic: temporary object for nop functions; dynamically allocated
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* @patched: the object's funcs have been added to the klp_ops list
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*/
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struct klp_object {
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/* external */
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const char *name;
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struct klp_func *funcs;
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struct klp_callbacks callbacks;
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/* internal */
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struct kobject kobj;
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struct list_head func_list;
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struct list_head node;
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struct module *mod;
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bool dynamic;
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bool patched;
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};
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/**
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* struct klp_state - state of the system modified by the livepatch
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* @id: system state identifier (non-zero)
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* @version: version of the change
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* @data: custom data
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*/
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struct klp_state {
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unsigned long id;
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unsigned int version;
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void *data;
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};
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/**
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* struct klp_patch - patch structure for live patching
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* @mod: reference to the live patch module
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* @objs: object entries for kernel objects to be patched
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* @states: system states that can get modified
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* @replace: replace all actively used patches
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* @list: list node for global list of actively used patches
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* @kobj: kobject for sysfs resources
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* @obj_list: dynamic list of the object entries
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* @enabled: the patch is enabled (but operation may be incomplete)
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* @forced: was involved in a forced transition
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* @free_work: patch cleanup from workqueue-context
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* @finish: for waiting till it is safe to remove the patch module
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*/
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struct klp_patch {
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/* external */
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struct module *mod;
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struct klp_object *objs;
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struct klp_state *states;
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bool replace;
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/* internal */
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struct list_head list;
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struct kobject kobj;
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struct list_head obj_list;
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bool enabled;
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bool forced;
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struct work_struct free_work;
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struct completion finish;
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};
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#define klp_for_each_object_static(patch, obj) \
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for (obj = patch->objs; obj->funcs || obj->name; obj++)
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#define klp_for_each_object_safe(patch, obj, tmp_obj) \
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list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node)
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#define klp_for_each_object(patch, obj) \
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list_for_each_entry(obj, &patch->obj_list, node)
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#define klp_for_each_func_static(obj, func) \
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for (func = obj->funcs; \
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func->old_name || func->new_func || func->old_sympos; \
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func++)
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#define klp_for_each_func_safe(obj, func, tmp_func) \
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list_for_each_entry_safe(func, tmp_func, &obj->func_list, node)
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#define klp_for_each_func(obj, func) \
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list_for_each_entry(func, &obj->func_list, node)
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int klp_enable_patch(struct klp_patch *);
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/* Called from the module loader during module coming/going states */
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int klp_module_coming(struct module *mod);
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void klp_module_going(struct module *mod);
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void klp_copy_process(struct task_struct *child);
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void klp_update_patch_state(struct task_struct *task);
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static inline bool klp_patch_pending(struct task_struct *task)
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{
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return test_tsk_thread_flag(task, TIF_PATCH_PENDING);
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}
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static inline bool klp_have_reliable_stack(void)
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{
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return IS_ENABLED(CONFIG_STACKTRACE) &&
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IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE);
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}
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typedef int (*klp_shadow_ctor_t)(void *obj,
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void *shadow_data,
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void *ctor_data);
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typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data);
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void *klp_shadow_get(void *obj, unsigned long id);
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void *klp_shadow_alloc(void *obj, unsigned long id,
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size_t size, gfp_t gfp_flags,
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klp_shadow_ctor_t ctor, void *ctor_data);
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void *klp_shadow_get_or_alloc(void *obj, unsigned long id,
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size_t size, gfp_t gfp_flags,
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klp_shadow_ctor_t ctor, void *ctor_data);
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void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor);
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void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor);
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struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id);
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struct klp_state *klp_get_prev_state(unsigned long id);
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int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
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const char *shstrtab, const char *strtab,
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unsigned int symindex, unsigned int secindex,
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const char *objname);
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#else /* !CONFIG_LIVEPATCH */
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static inline int klp_module_coming(struct module *mod) { return 0; }
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static inline void klp_module_going(struct module *mod) {}
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static inline bool klp_patch_pending(struct task_struct *task) { return false; }
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static inline void klp_update_patch_state(struct task_struct *task) {}
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static inline void klp_copy_process(struct task_struct *child) {}
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static inline
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int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
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const char *shstrtab, const char *strtab,
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unsigned int symindex, unsigned int secindex,
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const char *objname)
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{
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return 0;
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}
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#endif /* CONFIG_LIVEPATCH */
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#endif /* _LINUX_LIVEPATCH_H_ */
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