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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 | |
0430f78b | 38 | * @kobj_added: @kobj has been added and needs freeing |
e1452b60 | 39 | * @nop: temporary patch to use the original code again; dyn. allocated |
0dade9f3 | 40 | * @patched: the func has been added to the klp_ops list |
d83a7cb3 JP |
41 | * @transition: the func is currently being applied or reverted |
42 | * | |
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: | |
45 | * | |
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 | |
50 | * | |
51 | * And when unpatching, it goes in the reverse order: | |
52 | * | |
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 | |
b700e7f0 SJ |
57 | */ |
58 | struct klp_func { | |
59 | /* external */ | |
60 | const char *old_name; | |
61 | void *new_func; | |
62 | /* | |
b2b018ef CA |
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. | |
b700e7f0 | 68 | */ |
b2b018ef | 69 | unsigned long old_sympos; |
b700e7f0 SJ |
70 | |
71 | /* internal */ | |
19514910 | 72 | void *old_func; |
b700e7f0 | 73 | struct kobject kobj; |
20e55025 | 74 | struct list_head node; |
3c33f5b9 | 75 | struct list_head stack_node; |
f5e547f4 | 76 | unsigned long old_size, new_size; |
e1452b60 | 77 | bool nop; |
0dade9f3 | 78 | bool patched; |
d83a7cb3 | 79 | bool transition; |
b700e7f0 SJ |
80 | }; |
81 | ||
93862e38 JL |
82 | struct klp_object; |
83 | ||
84 | /** | |
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 | |
91 | * should run | |
92 | * | |
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. | |
97 | */ | |
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; | |
104 | }; | |
105 | ||
b700e7f0 SJ |
106 | /** |
107 | * struct klp_object - kernel object structure for live patching | |
108 | * @name: module name (or NULL for vmlinux) | |
b700e7f0 | 109 | * @funcs: function entries for functions to be patched in the object |
93862e38 | 110 | * @callbacks: functions to be executed pre/post (un)patching |
b700e7f0 | 111 | * @kobj: kobject for sysfs resources |
20e55025 JB |
112 | * @func_list: dynamic list of the function entries |
113 | * @node: list node for klp_patch obj_list | |
b700e7f0 | 114 | * @mod: kernel module associated with the patched object |
d83a7cb3 | 115 | * (NULL for vmlinux) |
0430f78b | 116 | * @kobj_added: @kobj has been added and needs freeing |
e1452b60 | 117 | * @dynamic: temporary object for nop functions; dynamically allocated |
0dade9f3 | 118 | * @patched: the object's funcs have been added to the klp_ops list |
b700e7f0 SJ |
119 | */ |
120 | struct klp_object { | |
121 | /* external */ | |
122 | const char *name; | |
b700e7f0 | 123 | struct klp_func *funcs; |
93862e38 | 124 | struct klp_callbacks callbacks; |
b700e7f0 SJ |
125 | |
126 | /* internal */ | |
cad706df | 127 | struct kobject kobj; |
20e55025 JB |
128 | struct list_head func_list; |
129 | struct list_head node; | |
b700e7f0 | 130 | struct module *mod; |
e1452b60 | 131 | bool dynamic; |
0dade9f3 | 132 | bool patched; |
b700e7f0 SJ |
133 | }; |
134 | ||
135 | /** | |
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 | |
e1452b60 | 139 | * @replace: replace all actively used patches |
958ef1e3 | 140 | * @list: list node for global list of actively used patches |
b700e7f0 | 141 | * @kobj: kobject for sysfs resources |
20e55025 | 142 | * @obj_list: dynamic list of the object entries |
0430f78b | 143 | * @kobj_added: @kobj has been added and needs freeing |
0dade9f3 | 144 | * @enabled: the patch is enabled (but operation may be incomplete) |
68007289 | 145 | * @forced: was involved in a forced transition |
958ef1e3 | 146 | * @free_work: patch cleanup from workqueue-context |
3ec24776 | 147 | * @finish: for waiting till it is safe to remove the patch module |
b700e7f0 SJ |
148 | */ |
149 | struct klp_patch { | |
150 | /* external */ | |
151 | struct module *mod; | |
152 | struct klp_object *objs; | |
e1452b60 | 153 | bool replace; |
b700e7f0 SJ |
154 | |
155 | /* internal */ | |
156 | struct list_head list; | |
157 | struct kobject kobj; | |
20e55025 | 158 | struct list_head obj_list; |
0dade9f3 | 159 | bool enabled; |
68007289 | 160 | bool forced; |
958ef1e3 | 161 | struct work_struct free_work; |
3ec24776 | 162 | struct completion finish; |
b700e7f0 SJ |
163 | }; |
164 | ||
20e55025 | 165 | #define klp_for_each_object_static(patch, obj) \ |
f09d9086 | 166 | for (obj = patch->objs; obj->funcs || obj->name; obj++) |
8cdd043a | 167 | |
e1452b60 JB |
168 | #define klp_for_each_object_safe(patch, obj, tmp_obj) \ |
169 | list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node) | |
170 | ||
20e55025 JB |
171 | #define klp_for_each_object(patch, obj) \ |
172 | list_for_each_entry(obj, &patch->obj_list, node) | |
173 | ||
174 | #define klp_for_each_func_static(obj, func) \ | |
f09d9086 MB |
175 | for (func = obj->funcs; \ |
176 | func->old_name || func->new_func || func->old_sympos; \ | |
177 | func++) | |
8cdd043a | 178 | |
e1452b60 JB |
179 | #define klp_for_each_func_safe(obj, func, tmp_func) \ |
180 | list_for_each_entry_safe(func, tmp_func, &obj->func_list, node) | |
181 | ||
20e55025 JB |
182 | #define klp_for_each_func(obj, func) \ |
183 | list_for_each_entry(func, &obj->func_list, node) | |
184 | ||
4421f8f0 | 185 | int klp_enable_patch(struct klp_patch *); |
b700e7f0 | 186 | |
255e732c JY |
187 | void arch_klp_init_object_loaded(struct klp_patch *patch, |
188 | struct klp_object *obj); | |
189 | ||
7e545d6e JY |
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); | |
193 | ||
d83a7cb3 | 194 | void klp_copy_process(struct task_struct *child); |
46c5a011 JP |
195 | void klp_update_patch_state(struct task_struct *task); |
196 | ||
d83a7cb3 JP |
197 | static inline bool klp_patch_pending(struct task_struct *task) |
198 | { | |
199 | return test_tsk_thread_flag(task, TIF_PATCH_PENDING); | |
200 | } | |
201 | ||
202 | static inline bool klp_have_reliable_stack(void) | |
203 | { | |
204 | return IS_ENABLED(CONFIG_STACKTRACE) && | |
205 | IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE); | |
206 | } | |
207 | ||
e91c2518 PM |
208 | typedef int (*klp_shadow_ctor_t)(void *obj, |
209 | void *shadow_data, | |
210 | void *ctor_data); | |
3b2c77d0 | 211 | typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data); |
e91c2518 | 212 | |
439e7271 | 213 | void *klp_shadow_get(void *obj, unsigned long id); |
e91c2518 PM |
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); | |
3b2c77d0 PM |
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); | |
439e7271 | 222 | |
7e545d6e JY |
223 | #else /* !CONFIG_LIVEPATCH */ |
224 | ||
225 | static inline int klp_module_coming(struct module *mod) { return 0; } | |
46c5a011 | 226 | static inline void klp_module_going(struct module *mod) {} |
d83a7cb3 | 227 | static inline bool klp_patch_pending(struct task_struct *task) { return false; } |
46c5a011 | 228 | static inline void klp_update_patch_state(struct task_struct *task) {} |
d83a7cb3 | 229 | static inline void klp_copy_process(struct task_struct *child) {} |
7e545d6e JY |
230 | |
231 | #endif /* CONFIG_LIVEPATCH */ | |
232 | ||
b700e7f0 | 233 | #endif /* _LINUX_LIVEPATCH_H_ */ |