include/linux/livepatch.h

   1 /*
   2  * livepatch.h - Kernel Live Patching Core
   3  *
   4  * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
   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 enum klp_state {
  32         KLP_DISABLED,
  33         KLP_ENABLED
  34 };
  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_addr:   a hint conveying at what address the old function
  41  *              can be found (optional, vmlinux patches only)
  42  * @kobj:       kobject for sysfs resources
  43  * @state:      tracks function-level patch application state
  44  * @stack_node: list node for klp_ops func_stack list
  45  */
  46 struct klp_func {
  47         /* external */
  48         const char *old_name;
  49         void *new_func;
  50         /*
  51          * The old_addr field is optional and can be used to resolve
  52          * duplicate symbol names in the vmlinux object.  If this
  53          * information is not present, the symbol is located by name
  54          * with kallsyms. If the name is not unique and old_addr is
  55          * not provided, the patch application fails as there is no
  56          * way to resolve the ambiguity.
  57          */
  58         unsigned long old_addr;
  59
  60         /* internal */
  61         struct kobject kobj;
  62         enum klp_state state;
  63         struct list_head stack_node;
  64 };
  65
  66 /**
  67  * struct klp_reloc - relocation structure for live patching
  68  * @loc:        address where the relocation will be written
  69  * @val:        address of the referenced symbol (optional,
  70  *              vmlinux patches only)
  71  * @type:       ELF relocation type
  72  * @name:       name of the referenced symbol (for lookup/verification)
  73  * @addend:     offset from the referenced symbol
  74  * @external:   symbol is either exported or within the live patch module itself
  75  */
  76 struct klp_reloc {
  77         unsigned long loc;
  78         unsigned long val;
  79         unsigned long type;
  80         const char *name;
  81         int addend;
  82         int external;
  83 };
  84
  85 /**
  86  * struct klp_object - kernel object structure for live patching
  87  * @name:       module name (or NULL for vmlinux)
  88  * @relocs:     relocation entries to be applied at load time
  89  * @funcs:      function entries for functions to be patched in the object
  90  * @kobj:       kobject for sysfs resources
  91  * @mod:        kernel module associated with the patched object
  92  *              (NULL for vmlinux)
  93  * @state:      tracks object-level patch application state
  94  */
  95 struct klp_object {
  96         /* external */
  97         const char *name;
  98         struct klp_reloc *relocs;
  99         struct klp_func *funcs;
 100
 101         /* internal */
 102         struct kobject *kobj;
 103         struct module *mod;
 104         enum klp_state state;
 105 };
 106
 107 /**
 108  * struct klp_patch - patch structure for live patching
 109  * @mod:        reference to the live patch module
 110  * @objs:       object entries for kernel objects to be patched
 111  * @list:       list node for global list of registered patches
 112  * @kobj:       kobject for sysfs resources
 113  * @state:      tracks patch-level application state
 114  */
 115 struct klp_patch {
 116         /* external */
 117         struct module *mod;
 118         struct klp_object *objs;
 119
 120         /* internal */
 121         struct list_head list;
 122         struct kobject kobj;
 123         enum klp_state state;
 124 };
 125
 126 extern int klp_register_patch(struct klp_patch *);
 127 extern int klp_unregister_patch(struct klp_patch *);
 128 extern int klp_enable_patch(struct klp_patch *);
 129 extern int klp_disable_patch(struct klp_patch *);
 130
 131 #endif /* CONFIG_LIVEPATCH */
 132
 133 #endif /* _LINUX_LIVEPATCH_H_ */