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1ccea77e | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
b700e7f0 SJ |
2 | /* |
3 | * livepatch.h - Kernel Live Patching Core | |
4 | * | |
5 | * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> | |
6 | * Copyright (C) 2014 SUSE | |
b700e7f0 SJ |
7 | */ |
8 | ||
9 | #ifndef _LINUX_LIVEPATCH_H_ | |
10 | #define _LINUX_LIVEPATCH_H_ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/ftrace.h> | |
3ec24776 | 14 | #include <linux/completion.h> |
20e55025 | 15 | #include <linux/list.h> |
b700e7f0 | 16 | |
7e545d6e JY |
17 | #if IS_ENABLED(CONFIG_LIVEPATCH) |
18 | ||
b700e7f0 SJ |
19 | #include <asm/livepatch.h> |
20 | ||
d83a7cb3 JP |
21 | /* task patch states */ |
22 | #define KLP_UNDEFINED -1 | |
23 | #define KLP_UNPATCHED 0 | |
24 | #define KLP_PATCHED 1 | |
25 | ||
b700e7f0 SJ |
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 | |
b2b018ef CA |
30 | * @old_sympos: a hint indicating which symbol position the old function |
31 | * can be found (optional) | |
19514910 | 32 | * @old_func: pointer to the function being patched |
b700e7f0 | 33 | * @kobj: kobject for sysfs resources |
20e55025 | 34 | * @node: list node for klp_object func_list |
3c33f5b9 | 35 | * @stack_node: list node for klp_ops func_stack list |
f5e547f4 JP |
36 | * @old_size: size of the old function |
37 | * @new_size: size of the new function | |
e1452b60 | 38 | * @nop: temporary patch to use the original code again; dyn. allocated |
0dade9f3 | 39 | * @patched: the func has been added to the klp_ops list |
d83a7cb3 JP |
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 | |
b700e7f0 SJ |
56 | */ |
57 | struct klp_func { | |
58 | /* external */ | |
59 | const char *old_name; | |
60 | void *new_func; | |
61 | /* | |
b2b018ef CA |
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. | |
b700e7f0 | 67 | */ |
b2b018ef | 68 | unsigned long old_sympos; |
b700e7f0 SJ |
69 | |
70 | /* internal */ | |
19514910 | 71 | void *old_func; |
b700e7f0 | 72 | struct kobject kobj; |
20e55025 | 73 | struct list_head node; |
3c33f5b9 | 74 | struct list_head stack_node; |
f5e547f4 | 75 | unsigned long old_size, new_size; |
e1452b60 | 76 | bool nop; |
0dade9f3 | 77 | bool patched; |
d83a7cb3 | 78 | bool transition; |
b700e7f0 SJ |
79 | }; |
80 | ||
93862e38 JL |
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 | ||
b700e7f0 SJ |
105 | /** |
106 | * struct klp_object - kernel object structure for live patching | |
107 | * @name: module name (or NULL for vmlinux) | |
b700e7f0 | 108 | * @funcs: function entries for functions to be patched in the object |
93862e38 | 109 | * @callbacks: functions to be executed pre/post (un)patching |
b700e7f0 | 110 | * @kobj: kobject for sysfs resources |
20e55025 JB |
111 | * @func_list: dynamic list of the function entries |
112 | * @node: list node for klp_patch obj_list | |
b700e7f0 | 113 | * @mod: kernel module associated with the patched object |
d83a7cb3 | 114 | * (NULL for vmlinux) |
e1452b60 | 115 | * @dynamic: temporary object for nop functions; dynamically allocated |
0dade9f3 | 116 | * @patched: the object's funcs have been added to the klp_ops list |
b700e7f0 SJ |
117 | */ |
118 | struct klp_object { | |
119 | /* external */ | |
120 | const char *name; | |
b700e7f0 | 121 | struct klp_func *funcs; |
93862e38 | 122 | struct klp_callbacks callbacks; |
b700e7f0 SJ |
123 | |
124 | /* internal */ | |
cad706df | 125 | struct kobject kobj; |
20e55025 JB |
126 | struct list_head func_list; |
127 | struct list_head node; | |
b700e7f0 | 128 | struct module *mod; |
e1452b60 | 129 | bool dynamic; |
0dade9f3 | 130 | bool patched; |
b700e7f0 SJ |
131 | }; |
132 | ||
73727f4d PM |
133 | /** |
134 | * struct klp_state - state of the system modified by the livepatch | |
135 | * @id: system state identifier (non-zero) | |
92c9abf5 | 136 | * @version: version of the change |
73727f4d PM |
137 | * @data: custom data |
138 | */ | |
139 | struct klp_state { | |
140 | unsigned long id; | |
92c9abf5 | 141 | unsigned int version; |
73727f4d PM |
142 | void *data; |
143 | }; | |
144 | ||
b700e7f0 SJ |
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 | |
73727f4d | 149 | * @states: system states that can get modified |
e1452b60 | 150 | * @replace: replace all actively used patches |
958ef1e3 | 151 | * @list: list node for global list of actively used patches |
b700e7f0 | 152 | * @kobj: kobject for sysfs resources |
20e55025 | 153 | * @obj_list: dynamic list of the object entries |
0dade9f3 | 154 | * @enabled: the patch is enabled (but operation may be incomplete) |
68007289 | 155 | * @forced: was involved in a forced transition |
958ef1e3 | 156 | * @free_work: patch cleanup from workqueue-context |
3ec24776 | 157 | * @finish: for waiting till it is safe to remove the patch module |
b700e7f0 SJ |
158 | */ |
159 | struct klp_patch { | |
160 | /* external */ | |
161 | struct module *mod; | |
162 | struct klp_object *objs; | |
73727f4d | 163 | struct klp_state *states; |
e1452b60 | 164 | bool replace; |
b700e7f0 SJ |
165 | |
166 | /* internal */ | |
167 | struct list_head list; | |
168 | struct kobject kobj; | |
20e55025 | 169 | struct list_head obj_list; |
0dade9f3 | 170 | bool enabled; |
68007289 | 171 | bool forced; |
958ef1e3 | 172 | struct work_struct free_work; |
3ec24776 | 173 | struct completion finish; |
b700e7f0 SJ |
174 | }; |
175 | ||
20e55025 | 176 | #define klp_for_each_object_static(patch, obj) \ |
f09d9086 | 177 | for (obj = patch->objs; obj->funcs || obj->name; obj++) |
8cdd043a | 178 | |
e1452b60 JB |
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 | ||
20e55025 JB |
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) \ | |
f09d9086 MB |
186 | for (func = obj->funcs; \ |
187 | func->old_name || func->new_func || func->old_sympos; \ | |
188 | func++) | |
8cdd043a | 189 | |
e1452b60 JB |
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 | ||
20e55025 JB |
193 | #define klp_for_each_func(obj, func) \ |
194 | list_for_each_entry(func, &obj->func_list, node) | |
195 | ||
4421f8f0 | 196 | int klp_enable_patch(struct klp_patch *); |
b700e7f0 | 197 | |
7e545d6e JY |
198 | /* Called from the module loader during module coming/going states */ |
199 | int klp_module_coming(struct module *mod); | |
200 | void klp_module_going(struct module *mod); | |
201 | ||
d83a7cb3 | 202 | void klp_copy_process(struct task_struct *child); |
46c5a011 JP |
203 | void klp_update_patch_state(struct task_struct *task); |
204 | ||
d83a7cb3 JP |
205 | static inline bool klp_patch_pending(struct task_struct *task) |
206 | { | |
207 | return test_tsk_thread_flag(task, TIF_PATCH_PENDING); | |
208 | } | |
209 | ||
210 | static inline bool klp_have_reliable_stack(void) | |
211 | { | |
212 | return IS_ENABLED(CONFIG_STACKTRACE) && | |
213 | IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE); | |
214 | } | |
215 | ||
e91c2518 PM |
216 | typedef int (*klp_shadow_ctor_t)(void *obj, |
217 | void *shadow_data, | |
218 | void *ctor_data); | |
3b2c77d0 | 219 | typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data); |
e91c2518 | 220 | |
439e7271 | 221 | void *klp_shadow_get(void *obj, unsigned long id); |
e91c2518 PM |
222 | void *klp_shadow_alloc(void *obj, unsigned long id, |
223 | size_t size, gfp_t gfp_flags, | |
224 | klp_shadow_ctor_t ctor, void *ctor_data); | |
225 | void *klp_shadow_get_or_alloc(void *obj, unsigned long id, | |
226 | size_t size, gfp_t gfp_flags, | |
227 | klp_shadow_ctor_t ctor, void *ctor_data); | |
3b2c77d0 PM |
228 | void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor); |
229 | void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor); | |
439e7271 | 230 | |
73727f4d PM |
231 | struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id); |
232 | struct klp_state *klp_get_prev_state(unsigned long id); | |
233 | ||
7c8e2bdd JP |
234 | int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, |
235 | const char *shstrtab, const char *strtab, | |
236 | unsigned int symindex, unsigned int secindex, | |
237 | const char *objname); | |
238 | ||
7e545d6e JY |
239 | #else /* !CONFIG_LIVEPATCH */ |
240 | ||
241 | static inline int klp_module_coming(struct module *mod) { return 0; } | |
46c5a011 | 242 | static inline void klp_module_going(struct module *mod) {} |
d83a7cb3 | 243 | static inline bool klp_patch_pending(struct task_struct *task) { return false; } |
46c5a011 | 244 | static inline void klp_update_patch_state(struct task_struct *task) {} |
d83a7cb3 | 245 | static inline void klp_copy_process(struct task_struct *child) {} |
7e545d6e | 246 | |
7c8e2bdd JP |
247 | static inline |
248 | int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, | |
249 | const char *shstrtab, const char *strtab, | |
250 | unsigned int symindex, unsigned int secindex, | |
251 | const char *objname) | |
252 | { | |
253 | return 0; | |
254 | } | |
255 | ||
7e545d6e JY |
256 | #endif /* CONFIG_LIVEPATCH */ |
257 | ||
b700e7f0 | 258 | #endif /* _LINUX_LIVEPATCH_H_ */ |