mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 11:19:37 +00:00
![Petr Mladek](/assets/img/avatar_default.png)
The atomic replace runs pre/post (un)install callbacks only from the new livepatch. There are several reasons for this: + Simplicity: clear ordering of operations, no interactions between old and new callbacks. + Reliability: only new livepatch knows what changes can already be made by older livepatches and how to take over the state. + Testing: the atomic replace can be properly tested only when a newer livepatch is available. It might be too late to fix unwanted effect of callbacks from older livepatches. It might happen that an older change is not enough and the same system state has to be modified another way. Different changes need to get distinguished by a version number added to struct klp_state. The version can also be used to prevent loading incompatible livepatches. The check is done when the livepatch is enabled. The rules are: + Any completely new system state modification is allowed. + System state modifications with the same or higher version are allowed for already modified system states. + Cumulative livepatches must handle all system state modifications from already installed livepatches. + Non-cumulative livepatches are allowed to touch already modified system states. Link: http://lkml.kernel.org/r/20191030154313.13263-4-pmladek@suse.com To: Jiri Kosina <jikos@kernel.org> Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Cc: Nicolai Stange <nstange@suse.de> Cc: live-patching@vger.kernel.org Cc: linux-kernel@vger.kernel.org Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
247 lines
7.9 KiB
C
247 lines
7.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
|
|
/*
|
|
* livepatch.h - Kernel Live Patching Core
|
|
*
|
|
* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
|
|
* Copyright (C) 2014 SUSE
|
|
*/
|
|
|
|
#ifndef _LINUX_LIVEPATCH_H_
|
|
#define _LINUX_LIVEPATCH_H_
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/ftrace.h>
|
|
#include <linux/completion.h>
|
|
#include <linux/list.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_func: pointer to the function being patched
|
|
* @kobj: kobject for sysfs resources
|
|
* @node: list node for klp_object func_list
|
|
* @stack_node: list node for klp_ops func_stack list
|
|
* @old_size: size of the old function
|
|
* @new_size: size of the new function
|
|
* @nop: temporary patch to use the original code again; dyn. allocated
|
|
* @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 */
|
|
void *old_func;
|
|
struct kobject kobj;
|
|
struct list_head node;
|
|
struct list_head stack_node;
|
|
unsigned long old_size, new_size;
|
|
bool nop;
|
|
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
|
|
* @func_list: dynamic list of the function entries
|
|
* @node: list node for klp_patch obj_list
|
|
* @mod: kernel module associated with the patched object
|
|
* (NULL for vmlinux)
|
|
* @dynamic: temporary object for nop functions; dynamically allocated
|
|
* @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 list_head func_list;
|
|
struct list_head node;
|
|
struct module *mod;
|
|
bool dynamic;
|
|
bool patched;
|
|
};
|
|
|
|
/**
|
|
* struct klp_state - state of the system modified by the livepatch
|
|
* @id: system state identifier (non-zero)
|
|
* @version: version of the change
|
|
* @data: custom data
|
|
*/
|
|
struct klp_state {
|
|
unsigned long id;
|
|
unsigned int version;
|
|
void *data;
|
|
};
|
|
|
|
/**
|
|
* struct klp_patch - patch structure for live patching
|
|
* @mod: reference to the live patch module
|
|
* @objs: object entries for kernel objects to be patched
|
|
* @states: system states that can get modified
|
|
* @replace: replace all actively used patches
|
|
* @list: list node for global list of actively used patches
|
|
* @kobj: kobject for sysfs resources
|
|
* @obj_list: dynamic list of the object entries
|
|
* @enabled: the patch is enabled (but operation may be incomplete)
|
|
* @forced: was involved in a forced transition
|
|
* @free_work: patch cleanup from workqueue-context
|
|
* @finish: for waiting till it is safe to remove the patch module
|
|
*/
|
|
struct klp_patch {
|
|
/* external */
|
|
struct module *mod;
|
|
struct klp_object *objs;
|
|
struct klp_state *states;
|
|
bool replace;
|
|
|
|
/* internal */
|
|
struct list_head list;
|
|
struct kobject kobj;
|
|
struct list_head obj_list;
|
|
bool enabled;
|
|
bool forced;
|
|
struct work_struct free_work;
|
|
struct completion finish;
|
|
};
|
|
|
|
#define klp_for_each_object_static(patch, obj) \
|
|
for (obj = patch->objs; obj->funcs || obj->name; obj++)
|
|
|
|
#define klp_for_each_object_safe(patch, obj, tmp_obj) \
|
|
list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node)
|
|
|
|
#define klp_for_each_object(patch, obj) \
|
|
list_for_each_entry(obj, &patch->obj_list, node)
|
|
|
|
#define klp_for_each_func_static(obj, func) \
|
|
for (func = obj->funcs; \
|
|
func->old_name || func->new_func || func->old_sympos; \
|
|
func++)
|
|
|
|
#define klp_for_each_func_safe(obj, func, tmp_func) \
|
|
list_for_each_entry_safe(func, tmp_func, &obj->func_list, node)
|
|
|
|
#define klp_for_each_func(obj, func) \
|
|
list_for_each_entry(func, &obj->func_list, node)
|
|
|
|
int klp_enable_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);
|
|
|
|
struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id);
|
|
struct klp_state *klp_get_prev_state(unsigned long id);
|
|
|
|
#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_ */
|