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Seth Jenningsb700e7f2014-12-16 11:58:19 -06001/*
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>
Josh Poimboeuf3ec24772017-03-06 11:20:29 -060026#include <linux/completion.h>
Seth Jenningsb700e7f2014-12-16 11:58:19 -060027
Jessica Yu7e545d62016-03-16 20:55:39 -040028#if IS_ENABLED(CONFIG_LIVEPATCH)
29
Seth Jenningsb700e7f2014-12-16 11:58:19 -060030#include <asm/livepatch.h>
31
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -060032/* task patch states */
33#define KLP_UNDEFINED -1
34#define KLP_UNPATCHED 0
35#define KLP_PATCHED 1
36
Seth Jenningsb700e7f2014-12-16 11:58:19 -060037/**
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
Chris J Argesb2b018e2015-12-01 20:40:54 -060041 * @old_sympos: a hint indicating which symbol position the old function
42 * can be found (optional)
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -060043 * @immediate: patch the func immediately, bypassing safety mechanisms
Chris J Argesb2b018e2015-12-01 20:40:54 -060044 * @old_addr: the address of the function being patched
Seth Jenningsb700e7f2014-12-16 11:58:19 -060045 * @kobj: kobject for sysfs resources
Josh Poimboeuf3c33f5b2015-01-20 09:26:19 -060046 * @stack_node: list node for klp_ops func_stack list
Josh Poimboeuff5e547f2017-02-13 19:42:39 -060047 * @old_size: size of the old function
48 * @new_size: size of the new function
Josh Poimboeuf0dade9f2017-02-13 19:42:35 -060049 * @patched: the func has been added to the klp_ops list
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -060050 * @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
Seth Jenningsb700e7f2014-12-16 11:58:19 -060066 */
67struct klp_func {
68 /* external */
69 const char *old_name;
70 void *new_func;
71 /*
Chris J Argesb2b018e2015-12-01 20:40:54 -060072 * 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.
Seth Jenningsb700e7f2014-12-16 11:58:19 -060077 */
Chris J Argesb2b018e2015-12-01 20:40:54 -060078 unsigned long old_sympos;
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -060079 bool immediate;
Seth Jenningsb700e7f2014-12-16 11:58:19 -060080
81 /* internal */
Chris J Argesb2b018e2015-12-01 20:40:54 -060082 unsigned long old_addr;
Seth Jenningsb700e7f2014-12-16 11:58:19 -060083 struct kobject kobj;
Josh Poimboeuf3c33f5b2015-01-20 09:26:19 -060084 struct list_head stack_node;
Josh Poimboeuff5e547f2017-02-13 19:42:39 -060085 unsigned long old_size, new_size;
Josh Poimboeuf0dade9f2017-02-13 19:42:35 -060086 bool patched;
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -060087 bool transition;
Seth Jenningsb700e7f2014-12-16 11:58:19 -060088};
89
90/**
Seth Jenningsb700e7f2014-12-16 11:58:19 -060091 * struct klp_object - kernel object structure for live patching
92 * @name: module name (or NULL for vmlinux)
Seth Jenningsb700e7f2014-12-16 11:58:19 -060093 * @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
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -060096 * (NULL for vmlinux)
Josh Poimboeuf0dade9f2017-02-13 19:42:35 -060097 * @patched: the object's funcs have been added to the klp_ops list
Seth Jenningsb700e7f2014-12-16 11:58:19 -060098 */
99struct klp_object {
100 /* external */
101 const char *name;
Seth Jenningsb700e7f2014-12-16 11:58:19 -0600102 struct klp_func *funcs;
103
104 /* internal */
Miroslav Benescad706d2015-05-19 12:01:18 +0200105 struct kobject kobj;
Seth Jenningsb700e7f2014-12-16 11:58:19 -0600106 struct module *mod;
Josh Poimboeuf0dade9f2017-02-13 19:42:35 -0600107 bool patched;
Seth Jenningsb700e7f2014-12-16 11:58:19 -0600108};
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
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -0600114 * @immediate: patch all funcs immediately, bypassing safety mechanisms
Seth Jenningsb700e7f2014-12-16 11:58:19 -0600115 * @list: list node for global list of registered patches
116 * @kobj: kobject for sysfs resources
Josh Poimboeuf0dade9f2017-02-13 19:42:35 -0600117 * @enabled: the patch is enabled (but operation may be incomplete)
Josh Poimboeuf3ec24772017-03-06 11:20:29 -0600118 * @finish: for waiting till it is safe to remove the patch module
Seth Jenningsb700e7f2014-12-16 11:58:19 -0600119 */
120struct klp_patch {
121 /* external */
122 struct module *mod;
123 struct klp_object *objs;
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -0600124 bool immediate;
Seth Jenningsb700e7f2014-12-16 11:58:19 -0600125
126 /* internal */
127 struct list_head list;
128 struct kobject kobj;
Josh Poimboeuf0dade9f2017-02-13 19:42:35 -0600129 bool enabled;
Josh Poimboeuf3ec24772017-03-06 11:20:29 -0600130 struct completion finish;
Seth Jenningsb700e7f2014-12-16 11:58:19 -0600131};
132
Jiri Slaby8cdd0432015-05-19 12:01:19 +0200133#define klp_for_each_object(patch, obj) \
Miroslav Benesf09d9082016-04-28 16:34:08 +0200134 for (obj = patch->objs; obj->funcs || obj->name; obj++)
Jiri Slaby8cdd0432015-05-19 12:01:19 +0200135
136#define klp_for_each_func(obj, func) \
Miroslav Benesf09d9082016-04-28 16:34:08 +0200137 for (func = obj->funcs; \
138 func->old_name || func->new_func || func->old_sympos; \
139 func++)
Jiri Slaby8cdd0432015-05-19 12:01:19 +0200140
Miroslav Benes4421f8f2015-02-18 15:21:07 +0100141int klp_register_patch(struct klp_patch *);
142int klp_unregister_patch(struct klp_patch *);
143int klp_enable_patch(struct klp_patch *);
144int klp_disable_patch(struct klp_patch *);
Seth Jenningsb700e7f2014-12-16 11:58:19 -0600145
Jessica Yu255e7322016-08-17 20:58:28 -0400146void arch_klp_init_object_loaded(struct klp_patch *patch,
147 struct klp_object *obj);
148
Jessica Yu7e545d62016-03-16 20:55:39 -0400149/* Called from the module loader during module coming/going states */
150int klp_module_coming(struct module *mod);
151void klp_module_going(struct module *mod);
152
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -0600153void klp_copy_process(struct task_struct *child);
Josh Poimboeuf46c5a012017-02-13 19:42:30 -0600154void klp_update_patch_state(struct task_struct *task);
155
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -0600156static inline bool klp_patch_pending(struct task_struct *task)
157{
158 return test_tsk_thread_flag(task, TIF_PATCH_PENDING);
159}
160
161static inline bool klp_have_reliable_stack(void)
162{
163 return IS_ENABLED(CONFIG_STACKTRACE) &&
164 IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE);
165}
166
Jessica Yu7e545d62016-03-16 20:55:39 -0400167#else /* !CONFIG_LIVEPATCH */
168
169static inline int klp_module_coming(struct module *mod) { return 0; }
Josh Poimboeuf46c5a012017-02-13 19:42:30 -0600170static inline void klp_module_going(struct module *mod) {}
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -0600171static inline bool klp_patch_pending(struct task_struct *task) { return false; }
Josh Poimboeuf46c5a012017-02-13 19:42:30 -0600172static inline void klp_update_patch_state(struct task_struct *task) {}
Josh Poimboeufd83a7cb2017-02-13 19:42:40 -0600173static inline void klp_copy_process(struct task_struct *child) {}
Jessica Yu7e545d62016-03-16 20:55:39 -0400174
175#endif /* CONFIG_LIVEPATCH */
176
Seth Jenningsb700e7f2014-12-16 11:58:19 -0600177#endif /* _LINUX_LIVEPATCH_H_ */