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 28 #if IS_ENABLED(CONFIG_LIVEPATCH) 29 30 #include <asm/livepatch.h> 31 32 /* task patch states */ 33 #define KLP_UNDEFINED -1 34 #define KLP_UNPATCHED 0 35 #define KLP_PATCHED 1 36 37 /** 38 * struct klp_func - function structure for live patching 39 * @old_name: name of the function to be patched 40 * @new_func: pointer to the patched function code 41 * @old_sympos: a hint indicating which symbol position the old function 42 * can be found (optional) 43 * @immediate: patch the func immediately, bypassing safety mechanisms 44 * @old_addr: the address of the function being patched 45 * @kobj: kobject for sysfs resources 46 * @stack_node: list node for klp_ops func_stack list 47 * @old_size: size of the old function 48 * @new_size: size of the new function 49 * @patched: the func has been added to the klp_ops list 50 * @transition: the func is currently being applied or reverted 51 * 52 * The patched and transition variables define the func's patching state. When 53 * patching, a func is always in one of the following states: 54 * 55 * patched=0 transition=0: unpatched 56 * patched=0 transition=1: unpatched, temporary starting state 57 * patched=1 transition=1: patched, may be visible to some tasks 58 * patched=1 transition=0: patched, visible to all tasks 59 * 60 * And when unpatching, it goes in the reverse order: 61 * 62 * patched=1 transition=0: patched, visible to all tasks 63 * patched=1 transition=1: patched, may be visible to some tasks 64 * patched=0 transition=1: unpatched, temporary ending state 65 * patched=0 transition=0: unpatched 66 */ 67 struct klp_func { 68 /* external */ 69 const char *old_name; 70 void *new_func; 71 /* 72 * The old_sympos field is optional and can be used to resolve 73 * duplicate symbol names in livepatch objects. If this field is zero, 74 * it is expected the symbol is unique, otherwise patching fails. If 75 * this value is greater than zero then that occurrence of the symbol 76 * in kallsyms for the given object is used. 77 */ 78 unsigned long old_sympos; 79 bool immediate; 80 81 /* internal */ 82 unsigned long old_addr; 83 struct kobject kobj; 84 struct list_head stack_node; 85 unsigned long old_size, new_size; 86 bool patched; 87 bool transition; 88 }; 89 90 /** 91 * struct klp_object - kernel object structure for live patching 92 * @name: module name (or NULL for vmlinux) 93 * @funcs: function entries for functions to be patched in the object 94 * @kobj: kobject for sysfs resources 95 * @mod: kernel module associated with the patched object 96 * (NULL for vmlinux) 97 * @patched: the object's funcs have been added to the klp_ops list 98 */ 99 struct klp_object { 100 /* external */ 101 const char *name; 102 struct klp_func *funcs; 103 104 /* internal */ 105 struct kobject kobj; 106 struct module *mod; 107 bool patched; 108 }; 109 110 /** 111 * struct klp_patch - patch structure for live patching 112 * @mod: reference to the live patch module 113 * @objs: object entries for kernel objects to be patched 114 * @immediate: patch all funcs immediately, bypassing safety mechanisms 115 * @list: list node for global list of registered patches 116 * @kobj: kobject for sysfs resources 117 * @enabled: the patch is enabled (but operation may be incomplete) 118 * @finish: for waiting till it is safe to remove the patch module 119 */ 120 struct klp_patch { 121 /* external */ 122 struct module *mod; 123 struct klp_object *objs; 124 bool immediate; 125 126 /* internal */ 127 struct list_head list; 128 struct kobject kobj; 129 bool enabled; 130 struct completion finish; 131 }; 132 133 #define klp_for_each_object(patch, obj) \ 134 for (obj = patch->objs; obj->funcs || obj->name; obj++) 135 136 #define klp_for_each_func(obj, func) \ 137 for (func = obj->funcs; \ 138 func->old_name || func->new_func || func->old_sympos; \ 139 func++) 140 141 int klp_register_patch(struct klp_patch *); 142 int klp_unregister_patch(struct klp_patch *); 143 int klp_enable_patch(struct klp_patch *); 144 int klp_disable_patch(struct klp_patch *); 145 146 void arch_klp_init_object_loaded(struct klp_patch *patch, 147 struct klp_object *obj); 148 149 /* Called from the module loader during module coming/going states */ 150 int klp_module_coming(struct module *mod); 151 void klp_module_going(struct module *mod); 152 153 void klp_copy_process(struct task_struct *child); 154 void klp_update_patch_state(struct task_struct *task); 155 156 static inline bool klp_patch_pending(struct task_struct *task) 157 { 158 return test_tsk_thread_flag(task, TIF_PATCH_PENDING); 159 } 160 161 static inline bool klp_have_reliable_stack(void) 162 { 163 return IS_ENABLED(CONFIG_STACKTRACE) && 164 IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE); 165 } 166 167 #else /* !CONFIG_LIVEPATCH */ 168 169 static inline int klp_module_coming(struct module *mod) { return 0; } 170 static inline void klp_module_going(struct module *mod) {} 171 static inline bool klp_patch_pending(struct task_struct *task) { return false; } 172 static inline void klp_update_patch_state(struct task_struct *task) {} 173 static inline void klp_copy_process(struct task_struct *child) {} 174 175 #endif /* CONFIG_LIVEPATCH */ 176 177 #endif /* _LINUX_LIVEPATCH_H_ */ 178