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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 | ||
d83a7cb3 JP |
19 | /* task patch states */ |
20 | #define KLP_UNDEFINED -1 | |
21 | #define KLP_UNPATCHED 0 | |
22 | #define KLP_PATCHED 1 | |
23 | ||
b700e7f0 SJ |
24 | /** |
25 | * struct klp_func - function structure for live patching | |
26 | * @old_name: name of the function to be patched | |
27 | * @new_func: pointer to the patched function code | |
b2b018ef CA |
28 | * @old_sympos: a hint indicating which symbol position the old function |
29 | * can be found (optional) | |
19514910 | 30 | * @old_func: pointer to the function being patched |
b700e7f0 | 31 | * @kobj: kobject for sysfs resources |
20e55025 | 32 | * @node: list node for klp_object func_list |
3c33f5b9 | 33 | * @stack_node: list node for klp_ops func_stack list |
f5e547f4 JP |
34 | * @old_size: size of the old function |
35 | * @new_size: size of the new function | |
e1452b60 | 36 | * @nop: temporary patch to use the original code again; dyn. allocated |
0dade9f3 | 37 | * @patched: the func has been added to the klp_ops list |
d83a7cb3 JP |
38 | * @transition: the func is currently being applied or reverted |
39 | * | |
40 | * The patched and transition variables define the func's patching state. When | |
41 | * patching, a func is always in one of the following states: | |
42 | * | |
43 | * patched=0 transition=0: unpatched | |
44 | * patched=0 transition=1: unpatched, temporary starting state | |
45 | * patched=1 transition=1: patched, may be visible to some tasks | |
46 | * patched=1 transition=0: patched, visible to all tasks | |
47 | * | |
48 | * And when unpatching, it goes in the reverse order: | |
49 | * | |
50 | * patched=1 transition=0: patched, visible to all tasks | |
51 | * patched=1 transition=1: patched, may be visible to some tasks | |
52 | * patched=0 transition=1: unpatched, temporary ending state | |
53 | * patched=0 transition=0: unpatched | |
b700e7f0 SJ |
54 | */ |
55 | struct klp_func { | |
56 | /* external */ | |
57 | const char *old_name; | |
58 | void *new_func; | |
59 | /* | |
b2b018ef CA |
60 | * The old_sympos field is optional and can be used to resolve |
61 | * duplicate symbol names in livepatch objects. If this field is zero, | |
62 | * it is expected the symbol is unique, otherwise patching fails. If | |
63 | * this value is greater than zero then that occurrence of the symbol | |
64 | * in kallsyms for the given object is used. | |
b700e7f0 | 65 | */ |
b2b018ef | 66 | unsigned long old_sympos; |
b700e7f0 SJ |
67 | |
68 | /* internal */ | |
19514910 | 69 | void *old_func; |
b700e7f0 | 70 | struct kobject kobj; |
20e55025 | 71 | struct list_head node; |
3c33f5b9 | 72 | struct list_head stack_node; |
f5e547f4 | 73 | unsigned long old_size, new_size; |
e1452b60 | 74 | bool nop; |
0dade9f3 | 75 | bool patched; |
d83a7cb3 | 76 | bool transition; |
b700e7f0 SJ |
77 | }; |
78 | ||
93862e38 JL |
79 | struct klp_object; |
80 | ||
81 | /** | |
82 | * struct klp_callbacks - pre/post live-(un)patch callback structure | |
83 | * @pre_patch: executed before code patching | |
84 | * @post_patch: executed after code patching | |
85 | * @pre_unpatch: executed before code unpatching | |
86 | * @post_unpatch: executed after code unpatching | |
87 | * @post_unpatch_enabled: flag indicating if post-unpatch callback | |
88 | * should run | |
89 | * | |
90 | * All callbacks are optional. Only the pre-patch callback, if provided, | |
91 | * will be unconditionally executed. If the parent klp_object fails to | |
92 | * patch for any reason, including a non-zero error status returned from | |
93 | * the pre-patch callback, no further callbacks will be executed. | |
94 | */ | |
95 | struct klp_callbacks { | |
96 | int (*pre_patch)(struct klp_object *obj); | |
97 | void (*post_patch)(struct klp_object *obj); | |
98 | void (*pre_unpatch)(struct klp_object *obj); | |
99 | void (*post_unpatch)(struct klp_object *obj); | |
100 | bool post_unpatch_enabled; | |
101 | }; | |
102 | ||
b700e7f0 SJ |
103 | /** |
104 | * struct klp_object - kernel object structure for live patching | |
105 | * @name: module name (or NULL for vmlinux) | |
b700e7f0 | 106 | * @funcs: function entries for functions to be patched in the object |
93862e38 | 107 | * @callbacks: functions to be executed pre/post (un)patching |
b700e7f0 | 108 | * @kobj: kobject for sysfs resources |
20e55025 JB |
109 | * @func_list: dynamic list of the function entries |
110 | * @node: list node for klp_patch obj_list | |
b700e7f0 | 111 | * @mod: kernel module associated with the patched object |
d83a7cb3 | 112 | * (NULL for vmlinux) |
e1452b60 | 113 | * @dynamic: temporary object for nop functions; dynamically allocated |
0dade9f3 | 114 | * @patched: the object's funcs have been added to the klp_ops list |
b700e7f0 SJ |
115 | */ |
116 | struct klp_object { | |
117 | /* external */ | |
118 | const char *name; | |
b700e7f0 | 119 | struct klp_func *funcs; |
93862e38 | 120 | struct klp_callbacks callbacks; |
b700e7f0 SJ |
121 | |
122 | /* internal */ | |
cad706df | 123 | struct kobject kobj; |
20e55025 JB |
124 | struct list_head func_list; |
125 | struct list_head node; | |
b700e7f0 | 126 | struct module *mod; |
e1452b60 | 127 | bool dynamic; |
0dade9f3 | 128 | bool patched; |
b700e7f0 SJ |
129 | }; |
130 | ||
73727f4d PM |
131 | /** |
132 | * struct klp_state - state of the system modified by the livepatch | |
133 | * @id: system state identifier (non-zero) | |
92c9abf5 | 134 | * @version: version of the change |
73727f4d PM |
135 | * @data: custom data |
136 | */ | |
137 | struct klp_state { | |
138 | unsigned long id; | |
92c9abf5 | 139 | unsigned int version; |
73727f4d PM |
140 | void *data; |
141 | }; | |
142 | ||
b700e7f0 SJ |
143 | /** |
144 | * struct klp_patch - patch structure for live patching | |
145 | * @mod: reference to the live patch module | |
146 | * @objs: object entries for kernel objects to be patched | |
73727f4d | 147 | * @states: system states that can get modified |
e1452b60 | 148 | * @replace: replace all actively used patches |
958ef1e3 | 149 | * @list: list node for global list of actively used patches |
b700e7f0 | 150 | * @kobj: kobject for sysfs resources |
20e55025 | 151 | * @obj_list: dynamic list of the object entries |
0dade9f3 | 152 | * @enabled: the patch is enabled (but operation may be incomplete) |
68007289 | 153 | * @forced: was involved in a forced transition |
958ef1e3 | 154 | * @free_work: patch cleanup from workqueue-context |
3ec24776 | 155 | * @finish: for waiting till it is safe to remove the patch module |
b700e7f0 SJ |
156 | */ |
157 | struct klp_patch { | |
158 | /* external */ | |
159 | struct module *mod; | |
160 | struct klp_object *objs; | |
73727f4d | 161 | struct klp_state *states; |
e1452b60 | 162 | bool replace; |
b700e7f0 SJ |
163 | |
164 | /* internal */ | |
165 | struct list_head list; | |
166 | struct kobject kobj; | |
20e55025 | 167 | struct list_head obj_list; |
0dade9f3 | 168 | bool enabled; |
68007289 | 169 | bool forced; |
958ef1e3 | 170 | struct work_struct free_work; |
3ec24776 | 171 | struct completion finish; |
b700e7f0 SJ |
172 | }; |
173 | ||
20e55025 | 174 | #define klp_for_each_object_static(patch, obj) \ |
f09d9086 | 175 | for (obj = patch->objs; obj->funcs || obj->name; obj++) |
8cdd043a | 176 | |
e1452b60 JB |
177 | #define klp_for_each_object_safe(patch, obj, tmp_obj) \ |
178 | list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node) | |
179 | ||
20e55025 JB |
180 | #define klp_for_each_object(patch, obj) \ |
181 | list_for_each_entry(obj, &patch->obj_list, node) | |
182 | ||
183 | #define klp_for_each_func_static(obj, func) \ | |
f09d9086 MB |
184 | for (func = obj->funcs; \ |
185 | func->old_name || func->new_func || func->old_sympos; \ | |
186 | func++) | |
8cdd043a | 187 | |
e1452b60 JB |
188 | #define klp_for_each_func_safe(obj, func, tmp_func) \ |
189 | list_for_each_entry_safe(func, tmp_func, &obj->func_list, node) | |
190 | ||
20e55025 JB |
191 | #define klp_for_each_func(obj, func) \ |
192 | list_for_each_entry(func, &obj->func_list, node) | |
193 | ||
4421f8f0 | 194 | int klp_enable_patch(struct klp_patch *); |
b700e7f0 | 195 | |
7e545d6e JY |
196 | /* Called from the module loader during module coming/going states */ |
197 | int klp_module_coming(struct module *mod); | |
198 | void klp_module_going(struct module *mod); | |
199 | ||
d83a7cb3 | 200 | void klp_copy_process(struct task_struct *child); |
46c5a011 JP |
201 | void klp_update_patch_state(struct task_struct *task); |
202 | ||
d83a7cb3 JP |
203 | static inline bool klp_patch_pending(struct task_struct *task) |
204 | { | |
205 | return test_tsk_thread_flag(task, TIF_PATCH_PENDING); | |
206 | } | |
207 | ||
208 | static inline bool klp_have_reliable_stack(void) | |
209 | { | |
210 | return IS_ENABLED(CONFIG_STACKTRACE) && | |
211 | IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE); | |
212 | } | |
213 | ||
e91c2518 PM |
214 | typedef int (*klp_shadow_ctor_t)(void *obj, |
215 | void *shadow_data, | |
216 | void *ctor_data); | |
3b2c77d0 | 217 | typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data); |
e91c2518 | 218 | |
439e7271 | 219 | void *klp_shadow_get(void *obj, unsigned long id); |
e91c2518 PM |
220 | void *klp_shadow_alloc(void *obj, unsigned long id, |
221 | size_t size, gfp_t gfp_flags, | |
222 | klp_shadow_ctor_t ctor, void *ctor_data); | |
223 | void *klp_shadow_get_or_alloc(void *obj, unsigned long id, | |
224 | size_t size, gfp_t gfp_flags, | |
225 | klp_shadow_ctor_t ctor, void *ctor_data); | |
3b2c77d0 PM |
226 | void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor); |
227 | void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor); | |
439e7271 | 228 | |
73727f4d PM |
229 | struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id); |
230 | struct klp_state *klp_get_prev_state(unsigned long id); | |
231 | ||
7c8e2bdd JP |
232 | int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, |
233 | const char *shstrtab, const char *strtab, | |
234 | unsigned int symindex, unsigned int secindex, | |
235 | const char *objname); | |
236 | ||
7e545d6e JY |
237 | #else /* !CONFIG_LIVEPATCH */ |
238 | ||
239 | static inline int klp_module_coming(struct module *mod) { return 0; } | |
46c5a011 | 240 | static inline void klp_module_going(struct module *mod) {} |
d83a7cb3 | 241 | static inline bool klp_patch_pending(struct task_struct *task) { return false; } |
46c5a011 | 242 | static inline void klp_update_patch_state(struct task_struct *task) {} |
d83a7cb3 | 243 | static inline void klp_copy_process(struct task_struct *child) {} |
7e545d6e | 244 | |
7c8e2bdd JP |
245 | static inline |
246 | int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, | |
247 | const char *shstrtab, const char *strtab, | |
248 | unsigned int symindex, unsigned int secindex, | |
249 | const char *objname) | |
250 | { | |
251 | return 0; | |
252 | } | |
253 | ||
7e545d6e JY |
254 | #endif /* CONFIG_LIVEPATCH */ |
255 | ||
b700e7f0 | 256 | #endif /* _LINUX_LIVEPATCH_H_ */ |