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/*
* livepatch.h - Kernel Live Patching Core
*
* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
* Copyright (C) 2014 SUSE
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _LINUX_LIVEPATCH_H_
#define _LINUX_LIVEPATCH_H_
#include <linux/module.h>
#include <linux/ftrace.h>
#include <linux/completion.h>
#if IS_ENABLED(CONFIG_LIVEPATCH)
#include <asm/livepatch.h>
/* task patch states */
#define KLP_UNDEFINED -1
#define KLP_UNPATCHED 0
#define KLP_PATCHED 1
/**
* struct klp_func - function structure for live patching
* @old_name: name of the function to be patched
* @new_func: pointer to the patched function code
* @old_sympos: a hint indicating which symbol position the old function
* can be found (optional)
* @old_addr: the address of the function being patched
* @kobj: kobject for sysfs resources
* @stack_node: list node for klp_ops func_stack list
* @old_size: size of the old function
* @new_size: size of the new function
* @patched: the func has been added to the klp_ops list
* @transition: the func is currently being applied or reverted
*
* The patched and transition variables define the func's patching state. When
* patching, a func is always in one of the following states:
*
* patched=0 transition=0: unpatched
* patched=0 transition=1: unpatched, temporary starting state
* patched=1 transition=1: patched, may be visible to some tasks
* patched=1 transition=0: patched, visible to all tasks
*
* And when unpatching, it goes in the reverse order:
*
* patched=1 transition=0: patched, visible to all tasks
* patched=1 transition=1: patched, may be visible to some tasks
* patched=0 transition=1: unpatched, temporary ending state
* patched=0 transition=0: unpatched
*/
struct klp_func {
/* external */
const char *old_name;
void *new_func;
/*
* The old_sympos field is optional and can be used to resolve
* duplicate symbol names in livepatch objects. If this field is zero,
* it is expected the symbol is unique, otherwise patching fails. If
* this value is greater than zero then that occurrence of the symbol
* in kallsyms for the given object is used.
*/
unsigned long old_sympos;
/* internal */
unsigned long old_addr;
struct kobject kobj;
struct list_head stack_node;
unsigned long old_size, new_size;
bool patched;
bool transition;
};
struct klp_object;
/**
* struct klp_callbacks - pre/post live-(un)patch callback structure
* @pre_patch: executed before code patching
* @post_patch: executed after code patching
* @pre_unpatch: executed before code unpatching
* @post_unpatch: executed after code unpatching
* @post_unpatch_enabled: flag indicating if post-unpatch callback
* should run
*
* All callbacks are optional. Only the pre-patch callback, if provided,
* will be unconditionally executed. If the parent klp_object fails to
* patch for any reason, including a non-zero error status returned from
* the pre-patch callback, no further callbacks will be executed.
*/
struct klp_callbacks {
int (*pre_patch)(struct klp_object *obj);
void (*post_patch)(struct klp_object *obj);
void (*pre_unpatch)(struct klp_object *obj);
void (*post_unpatch)(struct klp_object *obj);
bool post_unpatch_enabled;
};
/**
* struct klp_object - kernel object structure for live patching
* @name: module name (or NULL for vmlinux)
* @funcs: function entries for functions to be patched in the object
* @callbacks: functions to be executed pre/post (un)patching
* @kobj: kobject for sysfs resources
* @mod: kernel module associated with the patched object
* (NULL for vmlinux)
* @patched: the object's funcs have been added to the klp_ops list
*/
struct klp_object {
/* external */
const char *name;
struct klp_func *funcs;
struct klp_callbacks callbacks;
/* internal */
struct kobject kobj;
struct module *mod;
bool patched;
};
/**
* struct klp_patch - patch structure for live patching
* @mod: reference to the live patch module
* @objs: object entries for kernel objects to be patched
* @list: list node for global list of registered patches
* @kobj: kobject for sysfs resources
* @enabled: the patch is enabled (but operation may be incomplete)
* @finish: for waiting till it is safe to remove the patch module
*/
struct klp_patch {
/* external */
struct module *mod;
struct klp_object *objs;
/* internal */
struct list_head list;
struct kobject kobj;
bool enabled;
struct completion finish;
};
#define klp_for_each_object(patch, obj) \
for (obj = patch->objs; obj->funcs || obj->name; obj++)
#define klp_for_each_func(obj, func) \
for (func = obj->funcs; \
func->old_name || func->new_func || func->old_sympos; \
func++)
int klp_register_patch(struct klp_patch *);
int klp_unregister_patch(struct klp_patch *);
int klp_enable_patch(struct klp_patch *);
int klp_disable_patch(struct klp_patch *);
void arch_klp_init_object_loaded(struct klp_patch *patch,
struct klp_object *obj);
/* Called from the module loader during module coming/going states */
int klp_module_coming(struct module *mod);
void klp_module_going(struct module *mod);
void klp_copy_process(struct task_struct *child);
void klp_update_patch_state(struct task_struct *task);
static inline bool klp_patch_pending(struct task_struct *task)
{
return test_tsk_thread_flag(task, TIF_PATCH_PENDING);
}
static inline bool klp_have_reliable_stack(void)
{
return IS_ENABLED(CONFIG_STACKTRACE) &&
IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE);
}
typedef int (*klp_shadow_ctor_t)(void *obj,
void *shadow_data,
void *ctor_data);
typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data);
void *klp_shadow_get(void *obj, unsigned long id);
void *klp_shadow_alloc(void *obj, unsigned long id,
size_t size, gfp_t gfp_flags,
klp_shadow_ctor_t ctor, void *ctor_data);
void *klp_shadow_get_or_alloc(void *obj, unsigned long id,
size_t size, gfp_t gfp_flags,
klp_shadow_ctor_t ctor, void *ctor_data);
void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor);
void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor);
#else /* !CONFIG_LIVEPATCH */
static inline int klp_module_coming(struct module *mod) { return 0; }
static inline void klp_module_going(struct module *mod) {}
static inline bool klp_patch_pending(struct task_struct *task) { return false; }
static inline void klp_update_patch_state(struct task_struct *task) {}
static inline void klp_copy_process(struct task_struct *child) {}
#endif /* CONFIG_LIVEPATCH */
#endif /* _LINUX_LIVEPATCH_H_ */
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