/* * livepatch.h - Kernel Live Patching Core * * Copyright (C) 2014 Seth Jennings * 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 . */ #ifndef _LINUX_LIVEPATCH_H_ #define _LINUX_LIVEPATCH_H_ #include #include #include #if IS_ENABLED(CONFIG_LIVEPATCH) #include /* 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_ */