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1 : : /* SPDX-License-Identifier: GPL-2.0-or-later */
2 : : /*
3 : : * livepatch.h - Kernel Live Patching Core
4 : : *
5 : : * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
6 : : * Copyright (C) 2014 SUSE
7 : : */
8 : :
9 : : #ifndef _LINUX_LIVEPATCH_H_
10 : : #define _LINUX_LIVEPATCH_H_
11 : :
12 : : #include <linux/module.h>
13 : : #include <linux/ftrace.h>
14 : : #include <linux/completion.h>
15 : : #include <linux/list.h>
16 : :
17 : : #if IS_ENABLED(CONFIG_LIVEPATCH)
18 : :
19 : : #include <asm/livepatch.h>
20 : :
21 : : /* task patch states */
22 : : #define KLP_UNDEFINED -1
23 : : #define KLP_UNPATCHED 0
24 : : #define KLP_PATCHED 1
25 : :
26 : : /**
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 : : * @nop: temporary patch to use the original code again; dyn. allocated
39 : : * @patched: the func has been added to the klp_ops list
40 : : * @transition: the func is currently being applied or reverted
41 : : *
42 : : * The patched and transition variables define the func's patching state. When
43 : : * patching, a func is always in one of the following states:
44 : : *
45 : : * patched=0 transition=0: unpatched
46 : : * patched=0 transition=1: unpatched, temporary starting state
47 : : * patched=1 transition=1: patched, may be visible to some tasks
48 : : * patched=1 transition=0: patched, visible to all tasks
49 : : *
50 : : * And when unpatching, it goes in the reverse order:
51 : : *
52 : : * patched=1 transition=0: patched, visible to all tasks
53 : : * patched=1 transition=1: patched, may be visible to some tasks
54 : : * patched=0 transition=1: unpatched, temporary ending state
55 : : * patched=0 transition=0: unpatched
56 : : */
57 : : struct klp_func {
58 : : /* external */
59 : : const char *old_name;
60 : : void *new_func;
61 : : /*
62 : : * The old_sympos field is optional and can be used to resolve
63 : : * duplicate symbol names in livepatch objects. If this field is zero,
64 : : * it is expected the symbol is unique, otherwise patching fails. If
65 : : * this value is greater than zero then that occurrence of the symbol
66 : : * in kallsyms for the given object is used.
67 : : */
68 : : unsigned long old_sympos;
69 : :
70 : : /* internal */
71 : : void *old_func;
72 : : struct kobject kobj;
73 : : struct list_head node;
74 : : struct list_head stack_node;
75 : : unsigned long old_size, new_size;
76 : : bool nop;
77 : : bool patched;
78 : : bool transition;
79 : : };
80 : :
81 : : struct klp_object;
82 : :
83 : : /**
84 : : * struct klp_callbacks - pre/post live-(un)patch callback structure
85 : : * @pre_patch: executed before code patching
86 : : * @post_patch: executed after code patching
87 : : * @pre_unpatch: executed before code unpatching
88 : : * @post_unpatch: executed after code unpatching
89 : : * @post_unpatch_enabled: flag indicating if post-unpatch callback
90 : : * should run
91 : : *
92 : : * All callbacks are optional. Only the pre-patch callback, if provided,
93 : : * will be unconditionally executed. If the parent klp_object fails to
94 : : * patch for any reason, including a non-zero error status returned from
95 : : * the pre-patch callback, no further callbacks will be executed.
96 : : */
97 : : struct klp_callbacks {
98 : : int (*pre_patch)(struct klp_object *obj);
99 : : void (*post_patch)(struct klp_object *obj);
100 : : void (*pre_unpatch)(struct klp_object *obj);
101 : : void (*post_unpatch)(struct klp_object *obj);
102 : : bool post_unpatch_enabled;
103 : : };
104 : :
105 : : /**
106 : : * struct klp_object - kernel object structure for live patching
107 : : * @name: module name (or NULL for vmlinux)
108 : : * @funcs: function entries for functions to be patched in the object
109 : : * @callbacks: functions to be executed pre/post (un)patching
110 : : * @kobj: kobject for sysfs resources
111 : : * @func_list: dynamic list of the function entries
112 : : * @node: list node for klp_patch obj_list
113 : : * @mod: kernel module associated with the patched object
114 : : * (NULL for vmlinux)
115 : : * @dynamic: temporary object for nop functions; dynamically allocated
116 : : * @patched: the object's funcs have been added to the klp_ops list
117 : : */
118 : : struct klp_object {
119 : : /* external */
120 : : const char *name;
121 : : struct klp_func *funcs;
122 : : struct klp_callbacks callbacks;
123 : :
124 : : /* internal */
125 : : struct kobject kobj;
126 : : struct list_head func_list;
127 : : struct list_head node;
128 : : struct module *mod;
129 : : bool dynamic;
130 : : bool patched;
131 : : };
132 : :
133 : : /**
134 : : * struct klp_state - state of the system modified by the livepatch
135 : : * @id: system state identifier (non-zero)
136 : : * @version: version of the change
137 : : * @data: custom data
138 : : */
139 : : struct klp_state {
140 : : unsigned long id;
141 : : unsigned int version;
142 : : void *data;
143 : : };
144 : :
145 : : /**
146 : : * struct klp_patch - patch structure for live patching
147 : : * @mod: reference to the live patch module
148 : : * @objs: object entries for kernel objects to be patched
149 : : * @states: system states that can get modified
150 : : * @replace: replace all actively used patches
151 : : * @list: list node for global list of actively used patches
152 : : * @kobj: kobject for sysfs resources
153 : : * @obj_list: dynamic list of the object entries
154 : : * @enabled: the patch is enabled (but operation may be incomplete)
155 : : * @forced: was involved in a forced transition
156 : : * @free_work: patch cleanup from workqueue-context
157 : : * @finish: for waiting till it is safe to remove the patch module
158 : : */
159 : : struct klp_patch {
160 : : /* external */
161 : : struct module *mod;
162 : : struct klp_object *objs;
163 : : struct klp_state *states;
164 : : bool replace;
165 : :
166 : : /* internal */
167 : : struct list_head list;
168 : : struct kobject kobj;
169 : : struct list_head obj_list;
170 : : bool enabled;
171 : : bool forced;
172 : : struct work_struct free_work;
173 : : struct completion finish;
174 : : };
175 : :
176 : : #define klp_for_each_object_static(patch, obj) \
177 : : for (obj = patch->objs; obj->funcs || obj->name; obj++)
178 : :
179 : : #define klp_for_each_object_safe(patch, obj, tmp_obj) \
180 : : list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node)
181 : :
182 : : #define klp_for_each_object(patch, obj) \
183 : : list_for_each_entry(obj, &patch->obj_list, node)
184 : :
185 : : #define klp_for_each_func_static(obj, func) \
186 : : for (func = obj->funcs; \
187 : : func->old_name || func->new_func || func->old_sympos; \
188 : : func++)
189 : :
190 : : #define klp_for_each_func_safe(obj, func, tmp_func) \
191 : : list_for_each_entry_safe(func, tmp_func, &obj->func_list, node)
192 : :
193 : : #define klp_for_each_func(obj, func) \
194 : : list_for_each_entry(func, &obj->func_list, node)
195 : :
196 : : int klp_enable_patch(struct klp_patch *);
197 : :
198 : : void arch_klp_init_object_loaded(struct klp_patch *patch,
199 : : struct klp_object *obj);
200 : :
201 : : /* Called from the module loader during module coming/going states */
202 : : int klp_module_coming(struct module *mod);
203 : : void klp_module_going(struct module *mod);
204 : :
205 : : void klp_copy_process(struct task_struct *child);
206 : : void klp_update_patch_state(struct task_struct *task);
207 : :
208 : : static inline bool klp_patch_pending(struct task_struct *task)
209 : : {
210 : : return test_tsk_thread_flag(task, TIF_PATCH_PENDING);
211 : : }
212 : :
213 : : static inline bool klp_have_reliable_stack(void)
214 : : {
215 : : return IS_ENABLED(CONFIG_STACKTRACE) &&
216 : : IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE);
217 : : }
218 : :
219 : : typedef int (*klp_shadow_ctor_t)(void *obj,
220 : : void *shadow_data,
221 : : void *ctor_data);
222 : : typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data);
223 : :
224 : : void *klp_shadow_get(void *obj, unsigned long id);
225 : : void *klp_shadow_alloc(void *obj, unsigned long id,
226 : : size_t size, gfp_t gfp_flags,
227 : : klp_shadow_ctor_t ctor, void *ctor_data);
228 : : void *klp_shadow_get_or_alloc(void *obj, unsigned long id,
229 : : size_t size, gfp_t gfp_flags,
230 : : klp_shadow_ctor_t ctor, void *ctor_data);
231 : : void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor);
232 : : void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor);
233 : :
234 : : struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id);
235 : : struct klp_state *klp_get_prev_state(unsigned long id);
236 : :
237 : : #else /* !CONFIG_LIVEPATCH */
238 : :
239 : 9 : static inline int klp_module_coming(struct module *mod) { return 0; }
240 : 0 : static inline void klp_module_going(struct module *mod) {}
241 : 11922 : static inline bool klp_patch_pending(struct task_struct *task) { return false; }
242 : 0 : static inline void klp_update_patch_state(struct task_struct *task) {}
243 : 1397 : static inline void klp_copy_process(struct task_struct *child) {}
244 : :
245 : : #endif /* CONFIG_LIVEPATCH */
246 : :
247 : : #endif /* _LINUX_LIVEPATCH_H_ */
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