1 /* 2 * livepatch.h - Kernel Live Patching Core 3 * 4 * Copyright (C) 2014 Seth Jennings <[email protected]> 5 * Copyright (C) 2014 SUSE 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 2 10 * of the License, or (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, see <http://www.gnu.org/licenses/>. 19 */ 20 21 #ifndef _LINUX_LIVEPATCH_H_ 22 #define _LINUX_LIVEPATCH_H_ 23 24 #include <linux/module.h> 25 #include <linux/ftrace.h> 26 #include <linux/completion.h> 27 #include <linux/list.h> 28 29 #if IS_ENABLED(CONFIG_LIVEPATCH) 30 31 #include <asm/livepatch.h> 32 33 /* task patch states */ 34 #define KLP_UNDEFINED -1 35 #define KLP_UNPATCHED 0 36 #define KLP_PATCHED 1 37 38 /** 39 * struct klp_func - function structure for live patching 40 * @old_name: name of the function to be patched 41 * @new_func: pointer to the patched function code 42 * @old_sympos: a hint indicating which symbol position the old function 43 * can be found (optional) 44 * @old_func: pointer to the function being patched 45 * @kobj: kobject for sysfs resources 46 * @node: list node for klp_object func_list 47 * @stack_node: list node for klp_ops func_stack list 48 * @old_size: size of the old function 49 * @new_size: size of the new function 50 * @kobj_added: @kobj has been added and needs freeing 51 * @nop: temporary patch to use the original code again; dyn. allocated 52 * @patched: the func has been added to the klp_ops list 53 * @transition: the func is currently being applied or reverted 54 * 55 * The patched and transition variables define the func's patching state. When 56 * patching, a func is always in one of the following states: 57 * 58 * patched=0 transition=0: unpatched 59 * patched=0 transition=1: unpatched, temporary starting state 60 * patched=1 transition=1: patched, may be visible to some tasks 61 * patched=1 transition=0: patched, visible to all tasks 62 * 63 * And when unpatching, it goes in the reverse order: 64 * 65 * patched=1 transition=0: patched, visible to all tasks 66 * patched=1 transition=1: patched, may be visible to some tasks 67 * patched=0 transition=1: unpatched, temporary ending state 68 * patched=0 transition=0: unpatched 69 */ 70 struct klp_func { 71 /* external */ 72 const char *old_name; 73 void *new_func; 74 /* 75 * The old_sympos field is optional and can be used to resolve 76 * duplicate symbol names in livepatch objects. If this field is zero, 77 * it is expected the symbol is unique, otherwise patching fails. If 78 * this value is greater than zero then that occurrence of the symbol 79 * in kallsyms for the given object is used. 80 */ 81 unsigned long old_sympos; 82 83 /* internal */ 84 void *old_func; 85 struct kobject kobj; 86 struct list_head node; 87 struct list_head stack_node; 88 unsigned long old_size, new_size; 89 bool kobj_added; 90 bool nop; 91 bool patched; 92 bool transition; 93 }; 94 95 struct klp_object; 96 97 /** 98 * struct klp_callbacks - pre/post live-(un)patch callback structure 99 * @pre_patch: executed before code patching 100 * @post_patch: executed after code patching 101 * @pre_unpatch: executed before code unpatching 102 * @post_unpatch: executed after code unpatching 103 * @post_unpatch_enabled: flag indicating if post-unpatch callback 104 * should run 105 * 106 * All callbacks are optional. Only the pre-patch callback, if provided, 107 * will be unconditionally executed. If the parent klp_object fails to 108 * patch for any reason, including a non-zero error status returned from 109 * the pre-patch callback, no further callbacks will be executed. 110 */ 111 struct klp_callbacks { 112 int (*pre_patch)(struct klp_object *obj); 113 void (*post_patch)(struct klp_object *obj); 114 void (*pre_unpatch)(struct klp_object *obj); 115 void (*post_unpatch)(struct klp_object *obj); 116 bool post_unpatch_enabled; 117 }; 118 119 /** 120 * struct klp_object - kernel object structure for live patching 121 * @name: module name (or NULL for vmlinux) 122 * @funcs: function entries for functions to be patched in the object 123 * @callbacks: functions to be executed pre/post (un)patching 124 * @kobj: kobject for sysfs resources 125 * @func_list: dynamic list of the function entries 126 * @node: list node for klp_patch obj_list 127 * @mod: kernel module associated with the patched object 128 * (NULL for vmlinux) 129 * @kobj_added: @kobj has been added and needs freeing 130 * @dynamic: temporary object for nop functions; dynamically allocated 131 * @patched: the object's funcs have been added to the klp_ops list 132 */ 133 struct klp_object { 134 /* external */ 135 const char *name; 136 struct klp_func *funcs; 137 struct klp_callbacks callbacks; 138 139 /* internal */ 140 struct kobject kobj; 141 struct list_head func_list; 142 struct list_head node; 143 struct module *mod; 144 bool kobj_added; 145 bool dynamic; 146 bool patched; 147 }; 148 149 /** 150 * struct klp_patch - patch structure for live patching 151 * @mod: reference to the live patch module 152 * @objs: object entries for kernel objects to be patched 153 * @replace: replace all actively used patches 154 * @list: list node for global list of actively used patches 155 * @kobj: kobject for sysfs resources 156 * @obj_list: dynamic list of the object entries 157 * @kobj_added: @kobj has been added and needs freeing 158 * @enabled: the patch is enabled (but operation may be incomplete) 159 * @forced: was involved in a forced transition 160 * @free_work: patch cleanup from workqueue-context 161 * @finish: for waiting till it is safe to remove the patch module 162 */ 163 struct klp_patch { 164 /* external */ 165 struct module *mod; 166 struct klp_object *objs; 167 bool replace; 168 169 /* internal */ 170 struct list_head list; 171 struct kobject kobj; 172 struct list_head obj_list; 173 bool kobj_added; 174 bool enabled; 175 bool forced; 176 struct work_struct free_work; 177 struct completion finish; 178 }; 179 180 #define klp_for_each_object_static(patch, obj) \ 181 for (obj = patch->objs; obj->funcs || obj->name; obj++) 182 183 #define klp_for_each_object_safe(patch, obj, tmp_obj) \ 184 list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node) 185 186 #define klp_for_each_object(patch, obj) \ 187 list_for_each_entry(obj, &patch->obj_list, node) 188 189 #define klp_for_each_func_static(obj, func) \ 190 for (func = obj->funcs; \ 191 func->old_name || func->new_func || func->old_sympos; \ 192 func++) 193 194 #define klp_for_each_func_safe(obj, func, tmp_func) \ 195 list_for_each_entry_safe(func, tmp_func, &obj->func_list, node) 196 197 #define klp_for_each_func(obj, func) \ 198 list_for_each_entry(func, &obj->func_list, node) 199 200 int klp_enable_patch(struct klp_patch *); 201 202 void arch_klp_init_object_loaded(struct klp_patch *patch, 203 struct klp_object *obj); 204 205 /* Called from the module loader during module coming/going states */ 206 int klp_module_coming(struct module *mod); 207 void klp_module_going(struct module *mod); 208 209 void klp_copy_process(struct task_struct *child); 210 void klp_update_patch_state(struct task_struct *task); 211 212 static inline bool klp_patch_pending(struct task_struct *task) 213 { 214 return test_tsk_thread_flag(task, TIF_PATCH_PENDING); 215 } 216 217 static inline bool klp_have_reliable_stack(void) 218 { 219 return IS_ENABLED(CONFIG_STACKTRACE) && 220 IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE); 221 } 222 223 typedef int (*klp_shadow_ctor_t)(void *obj, 224 void *shadow_data, 225 void *ctor_data); 226 typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data); 227 228 void *klp_shadow_get(void *obj, unsigned long id); 229 void *klp_shadow_alloc(void *obj, unsigned long id, 230 size_t size, gfp_t gfp_flags, 231 klp_shadow_ctor_t ctor, void *ctor_data); 232 void *klp_shadow_get_or_alloc(void *obj, unsigned long id, 233 size_t size, gfp_t gfp_flags, 234 klp_shadow_ctor_t ctor, void *ctor_data); 235 void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor); 236 void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor); 237 238 #else /* !CONFIG_LIVEPATCH */ 239 240 static inline int klp_module_coming(struct module *mod) { return 0; } 241 static inline void klp_module_going(struct module *mod) {} 242 static inline bool klp_patch_pending(struct task_struct *task) { return false; } 243 static inline void klp_update_patch_state(struct task_struct *task) {} 244 static inline void klp_copy_process(struct task_struct *child) {} 245 246 #endif /* CONFIG_LIVEPATCH */ 247 248 #endif /* _LINUX_LIVEPATCH_H_ */ 249