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