1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * livepatch.h - Kernel Live Patching Core 4 * 5 * Copyright (C) 2014 Seth Jennings <[email protected]> 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 * @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 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 57 */ 58 struct klp_func { 59 /* external */ 60 const char *old_name; 61 void *new_func; 62 /* 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. 68 */ 69 unsigned long old_sympos; 70 71 /* internal */ 72 void *old_func; 73 struct kobject kobj; 74 struct list_head node; 75 struct list_head stack_node; 76 unsigned long old_size, new_size; 77 bool nop; 78 bool patched; 79 bool transition; 80 }; 81 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 }; 105 106 /** 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 115 * (NULL for vmlinux) 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 119 */ 120 struct klp_object { 121 /* external */ 122 const char *name; 123 struct klp_func *funcs; 124 struct klp_callbacks callbacks; 125 126 /* internal */ 127 struct kobject kobj; 128 struct list_head func_list; 129 struct list_head node; 130 struct module *mod; 131 bool dynamic; 132 bool patched; 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 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 148 */ 149 struct klp_patch { 150 /* external */ 151 struct module *mod; 152 struct klp_object *objs; 153 bool replace; 154 155 /* internal */ 156 struct list_head list; 157 struct kobject kobj; 158 struct list_head obj_list; 159 bool enabled; 160 bool forced; 161 struct work_struct free_work; 162 struct completion finish; 163 }; 164 165 #define klp_for_each_object_static(patch, obj) \ 166 for (obj = patch->objs; obj->funcs || obj->name; obj++) 167 168 #define klp_for_each_object_safe(patch, obj, tmp_obj) \ 169 list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node) 170 171 #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) \ 175 for (func = obj->funcs; \ 176 func->old_name || func->new_func || func->old_sympos; \ 177 func++) 178 179 #define klp_for_each_func_safe(obj, func, tmp_func) \ 180 list_for_each_entry_safe(func, tmp_func, &obj->func_list, node) 181 182 #define klp_for_each_func(obj, func) \ 183 list_for_each_entry(func, &obj->func_list, node) 184 185 int klp_enable_patch(struct klp_patch *); 186 187 void arch_klp_init_object_loaded(struct klp_patch *patch, 188 struct klp_object *obj); 189 190 /* 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); 193 194 void klp_copy_process(struct task_struct *child); 195 void klp_update_patch_state(struct task_struct *task); 196 197 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 } 207 208 typedef int (*klp_shadow_ctor_t)(void *obj, 209 void *shadow_data, 210 void *ctor_data); 211 typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data); 212 213 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); 222 223 #else /* !CONFIG_LIVEPATCH */ 224 225 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) {} 230 231 #endif /* CONFIG_LIVEPATCH */ 232 233 #endif /* _LINUX_LIVEPATCH_H_ */ 234