1 /* SPDX-License-Identifier: GPL-2.0-or-later */
3 * livepatch.h - Kernel Live Patching Core
5 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
6 * Copyright (C) 2014 SUSE
9 #ifndef _LINUX_LIVEPATCH_H_
10 #define _LINUX_LIVEPATCH_H_
12 #include <linux/module.h>
13 #include <linux/ftrace.h>
14 #include <linux/completion.h>
15 #include <linux/list.h>
17 #if IS_ENABLED(CONFIG_LIVEPATCH)
19 #include <asm/livepatch.h>
21 /* task patch states */
22 #define KLP_UNDEFINED -1
23 #define KLP_UNPATCHED 0
27 * struct klp_func - function structure for live patching
28 * @old_name: name of the function to be patched
29 * @new_func: pointer to the patched function code
30 * @old_sympos: a hint indicating which symbol position the old function
31 * can be found (optional)
32 * @old_func: pointer to the function being patched
33 * @kobj: kobject for sysfs resources
34 * @node: list node for klp_object func_list
35 * @stack_node: list node for klp_ops func_stack list
36 * @old_size: size of the old function
37 * @new_size: size of the new function
38 * @kobj_added: @kobj has been added and needs freeing
39 * @nop: temporary patch to use the original code again; dyn. allocated
40 * @patched: the func has been added to the klp_ops list
41 * @transition: the func is currently being applied or reverted
43 * The patched and transition variables define the func's patching state. When
44 * patching, a func is always in one of the following states:
46 * patched=0 transition=0: unpatched
47 * patched=0 transition=1: unpatched, temporary starting state
48 * patched=1 transition=1: patched, may be visible to some tasks
49 * patched=1 transition=0: patched, visible to all tasks
51 * And when unpatching, it goes in the reverse order:
53 * patched=1 transition=0: patched, visible to all tasks
54 * patched=1 transition=1: patched, may be visible to some tasks
55 * patched=0 transition=1: unpatched, temporary ending state
56 * patched=0 transition=0: unpatched
63 * The old_sympos field is optional and can be used to resolve
64 * duplicate symbol names in livepatch objects. If this field is zero,
65 * it is expected the symbol is unique, otherwise patching fails. If
66 * this value is greater than zero then that occurrence of the symbol
67 * in kallsyms for the given object is used.
69 unsigned long old_sympos
;
74 struct list_head node
;
75 struct list_head stack_node
;
76 unsigned long old_size
, new_size
;
85 * struct klp_callbacks - pre/post live-(un)patch callback structure
86 * @pre_patch: executed before code patching
87 * @post_patch: executed after code patching
88 * @pre_unpatch: executed before code unpatching
89 * @post_unpatch: executed after code unpatching
90 * @post_unpatch_enabled: flag indicating if post-unpatch callback
93 * All callbacks are optional. Only the pre-patch callback, if provided,
94 * will be unconditionally executed. If the parent klp_object fails to
95 * patch for any reason, including a non-zero error status returned from
96 * the pre-patch callback, no further callbacks will be executed.
98 struct klp_callbacks
{
99 int (*pre_patch
)(struct klp_object
*obj
);
100 void (*post_patch
)(struct klp_object
*obj
);
101 void (*pre_unpatch
)(struct klp_object
*obj
);
102 void (*post_unpatch
)(struct klp_object
*obj
);
103 bool post_unpatch_enabled
;
107 * struct klp_object - kernel object structure for live patching
108 * @name: module name (or NULL for vmlinux)
109 * @funcs: function entries for functions to be patched in the object
110 * @callbacks: functions to be executed pre/post (un)patching
111 * @kobj: kobject for sysfs resources
112 * @func_list: dynamic list of the function entries
113 * @node: list node for klp_patch obj_list
114 * @mod: kernel module associated with the patched object
116 * @kobj_added: @kobj has been added and needs freeing
117 * @dynamic: temporary object for nop functions; dynamically allocated
118 * @patched: the object's funcs have been added to the klp_ops list
123 struct klp_func
*funcs
;
124 struct klp_callbacks callbacks
;
128 struct list_head func_list
;
129 struct list_head node
;
136 * struct klp_patch - patch structure for live patching
137 * @mod: reference to the live patch module
138 * @objs: object entries for kernel objects to be patched
139 * @replace: replace all actively used patches
140 * @list: list node for global list of actively used patches
141 * @kobj: kobject for sysfs resources
142 * @obj_list: dynamic list of the object entries
143 * @kobj_added: @kobj has been added and needs freeing
144 * @enabled: the patch is enabled (but operation may be incomplete)
145 * @forced: was involved in a forced transition
146 * @free_work: patch cleanup from workqueue-context
147 * @finish: for waiting till it is safe to remove the patch module
152 struct klp_object
*objs
;
156 struct list_head list
;
158 struct list_head obj_list
;
161 struct work_struct free_work
;
162 struct completion finish
;
165 #define klp_for_each_object_static(patch, obj) \
166 for (obj = patch->objs; obj->funcs || obj->name; obj++)
168 #define klp_for_each_object_safe(patch, obj, tmp_obj) \
169 list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node)
171 #define klp_for_each_object(patch, obj) \
172 list_for_each_entry(obj, &patch->obj_list, node)
174 #define klp_for_each_func_static(obj, func) \
175 for (func = obj->funcs; \
176 func->old_name || func->new_func || func->old_sympos; \
179 #define klp_for_each_func_safe(obj, func, tmp_func) \
180 list_for_each_entry_safe(func, tmp_func, &obj->func_list, node)
182 #define klp_for_each_func(obj, func) \
183 list_for_each_entry(func, &obj->func_list, node)
185 int klp_enable_patch(struct klp_patch
*);
187 void arch_klp_init_object_loaded(struct klp_patch
*patch
,
188 struct klp_object
*obj
);
190 /* Called from the module loader during module coming/going states */
191 int klp_module_coming(struct module
*mod
);
192 void klp_module_going(struct module
*mod
);
194 void klp_copy_process(struct task_struct
*child
);
195 void klp_update_patch_state(struct task_struct
*task
);
197 static inline bool klp_patch_pending(struct task_struct
*task
)
199 return test_tsk_thread_flag(task
, TIF_PATCH_PENDING
);
202 static inline bool klp_have_reliable_stack(void)
204 return IS_ENABLED(CONFIG_STACKTRACE
) &&
205 IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE
);
208 typedef int (*klp_shadow_ctor_t
)(void *obj
,
211 typedef void (*klp_shadow_dtor_t
)(void *obj
, void *shadow_data
);
213 void *klp_shadow_get(void *obj
, unsigned long id
);
214 void *klp_shadow_alloc(void *obj
, unsigned long id
,
215 size_t size
, gfp_t gfp_flags
,
216 klp_shadow_ctor_t ctor
, void *ctor_data
);
217 void *klp_shadow_get_or_alloc(void *obj
, unsigned long id
,
218 size_t size
, gfp_t gfp_flags
,
219 klp_shadow_ctor_t ctor
, void *ctor_data
);
220 void klp_shadow_free(void *obj
, unsigned long id
, klp_shadow_dtor_t dtor
);
221 void klp_shadow_free_all(unsigned long id
, klp_shadow_dtor_t dtor
);
223 #else /* !CONFIG_LIVEPATCH */
225 static inline int klp_module_coming(struct module
*mod
) { return 0; }
226 static inline void klp_module_going(struct module
*mod
) {}
227 static inline bool klp_patch_pending(struct task_struct
*task
) { return false; }
228 static inline void klp_update_patch_state(struct task_struct
*task
) {}
229 static inline void klp_copy_process(struct task_struct
*child
) {}
231 #endif /* CONFIG_LIVEPATCH */
233 #endif /* _LINUX_LIVEPATCH_H_ */