LCOV - code coverage report
Current view: top level - include/linux - livepatch.h (source / functions) Hit Total Coverage
Test: combined.info Lines: 3 5 60.0 %
Date: 2022-03-28 13:20:08 Functions: 0 0 -
Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : /* SPDX-License-Identifier: GPL-2.0-or-later */
       2                 :            : /*
       3                 :            :  * livepatch.h - Kernel Live Patching Core
       4                 :            :  *
       5                 :            :  * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
       6                 :            :  * Copyright (C) 2014 SUSE
       7                 :            :  */
       8                 :            : 
       9                 :            : #ifndef _LINUX_LIVEPATCH_H_
      10                 :            : #define _LINUX_LIVEPATCH_H_
      11                 :            : 
      12                 :            : #include <linux/module.h>
      13                 :            : #include <linux/ftrace.h>
      14                 :            : #include <linux/completion.h>
      15                 :            : #include <linux/list.h>
      16                 :            : 
      17                 :            : #if IS_ENABLED(CONFIG_LIVEPATCH)
      18                 :            : 
      19                 :            : #include <asm/livepatch.h>
      20                 :            : 
      21                 :            : /* task patch states */
      22                 :            : #define KLP_UNDEFINED   -1
      23                 :            : #define KLP_UNPATCHED    0
      24                 :            : #define KLP_PATCHED      1
      25                 :            : 
      26                 :            : /**
      27                 :            :  * struct klp_func - function structure for live patching
      28                 :            :  * @old_name:   name of the function to be patched
      29                 :            :  * @new_func:   pointer to the patched function code
      30                 :            :  * @old_sympos: a hint indicating which symbol position the old function
      31                 :            :  *              can be found (optional)
      32                 :            :  * @old_func:   pointer to the function being patched
      33                 :            :  * @kobj:       kobject for sysfs resources
      34                 :            :  * @node:       list node for klp_object func_list
      35                 :            :  * @stack_node: list node for klp_ops func_stack list
      36                 :            :  * @old_size:   size of the old function
      37                 :            :  * @new_size:   size of the new function
      38                 :            :  * @nop:        temporary patch to use the original code again; dyn. allocated
      39                 :            :  * @patched:    the func has been added to the klp_ops list
      40                 :            :  * @transition: the func is currently being applied or reverted
      41                 :            :  *
      42                 :            :  * The patched and transition variables define the func's patching state.  When
      43                 :            :  * patching, a func is always in one of the following states:
      44                 :            :  *
      45                 :            :  *   patched=0 transition=0: unpatched
      46                 :            :  *   patched=0 transition=1: unpatched, temporary starting state
      47                 :            :  *   patched=1 transition=1: patched, may be visible to some tasks
      48                 :            :  *   patched=1 transition=0: patched, visible to all tasks
      49                 :            :  *
      50                 :            :  * And when unpatching, it goes in the reverse order:
      51                 :            :  *
      52                 :            :  *   patched=1 transition=0: patched, visible to all tasks
      53                 :            :  *   patched=1 transition=1: patched, may be visible to some tasks
      54                 :            :  *   patched=0 transition=1: unpatched, temporary ending state
      55                 :            :  *   patched=0 transition=0: unpatched
      56                 :            :  */
      57                 :            : struct klp_func {
      58                 :            :         /* external */
      59                 :            :         const char *old_name;
      60                 :            :         void *new_func;
      61                 :            :         /*
      62                 :            :          * The old_sympos field is optional and can be used to resolve
      63                 :            :          * duplicate symbol names in livepatch objects. If this field is zero,
      64                 :            :          * it is expected the symbol is unique, otherwise patching fails. If
      65                 :            :          * this value is greater than zero then that occurrence of the symbol
      66                 :            :          * in kallsyms for the given object is used.
      67                 :            :          */
      68                 :            :         unsigned long old_sympos;
      69                 :            : 
      70                 :            :         /* internal */
      71                 :            :         void *old_func;
      72                 :            :         struct kobject kobj;
      73                 :            :         struct list_head node;
      74                 :            :         struct list_head stack_node;
      75                 :            :         unsigned long old_size, new_size;
      76                 :            :         bool nop;
      77                 :            :         bool patched;
      78                 :            :         bool transition;
      79                 :            : };
      80                 :            : 
      81                 :            : struct klp_object;
      82                 :            : 
      83                 :            : /**
      84                 :            :  * struct klp_callbacks - pre/post live-(un)patch callback structure
      85                 :            :  * @pre_patch:          executed before code patching
      86                 :            :  * @post_patch:         executed after code patching
      87                 :            :  * @pre_unpatch:        executed before code unpatching
      88                 :            :  * @post_unpatch:       executed after code unpatching
      89                 :            :  * @post_unpatch_enabled:       flag indicating if post-unpatch callback
      90                 :            :  *                              should run
      91                 :            :  *
      92                 :            :  * All callbacks are optional.  Only the pre-patch callback, if provided,
      93                 :            :  * will be unconditionally executed.  If the parent klp_object fails to
      94                 :            :  * patch for any reason, including a non-zero error status returned from
      95                 :            :  * the pre-patch callback, no further callbacks will be executed.
      96                 :            :  */
      97                 :            : struct klp_callbacks {
      98                 :            :         int (*pre_patch)(struct klp_object *obj);
      99                 :            :         void (*post_patch)(struct klp_object *obj);
     100                 :            :         void (*pre_unpatch)(struct klp_object *obj);
     101                 :            :         void (*post_unpatch)(struct klp_object *obj);
     102                 :            :         bool post_unpatch_enabled;
     103                 :            : };
     104                 :            : 
     105                 :            : /**
     106                 :            :  * struct klp_object - kernel object structure for live patching
     107                 :            :  * @name:       module name (or NULL for vmlinux)
     108                 :            :  * @funcs:      function entries for functions to be patched in the object
     109                 :            :  * @callbacks:  functions to be executed pre/post (un)patching
     110                 :            :  * @kobj:       kobject for sysfs resources
     111                 :            :  * @func_list:  dynamic list of the function entries
     112                 :            :  * @node:       list node for klp_patch obj_list
     113                 :            :  * @mod:        kernel module associated with the patched object
     114                 :            :  *              (NULL for vmlinux)
     115                 :            :  * @dynamic:    temporary object for nop functions; dynamically allocated
     116                 :            :  * @patched:    the object's funcs have been added to the klp_ops list
     117                 :            :  */
     118                 :            : struct klp_object {
     119                 :            :         /* external */
     120                 :            :         const char *name;
     121                 :            :         struct klp_func *funcs;
     122                 :            :         struct klp_callbacks callbacks;
     123                 :            : 
     124                 :            :         /* internal */
     125                 :            :         struct kobject kobj;
     126                 :            :         struct list_head func_list;
     127                 :            :         struct list_head node;
     128                 :            :         struct module *mod;
     129                 :            :         bool dynamic;
     130                 :            :         bool patched;
     131                 :            : };
     132                 :            : 
     133                 :            : /**
     134                 :            :  * struct klp_state - state of the system modified by the livepatch
     135                 :            :  * @id:         system state identifier (non-zero)
     136                 :            :  * @version:    version of the change
     137                 :            :  * @data:       custom data
     138                 :            :  */
     139                 :            : struct klp_state {
     140                 :            :         unsigned long id;
     141                 :            :         unsigned int version;
     142                 :            :         void *data;
     143                 :            : };
     144                 :            : 
     145                 :            : /**
     146                 :            :  * struct klp_patch - patch structure for live patching
     147                 :            :  * @mod:        reference to the live patch module
     148                 :            :  * @objs:       object entries for kernel objects to be patched
     149                 :            :  * @states:     system states that can get modified
     150                 :            :  * @replace:    replace all actively used patches
     151                 :            :  * @list:       list node for global list of actively used patches
     152                 :            :  * @kobj:       kobject for sysfs resources
     153                 :            :  * @obj_list:   dynamic list of the object entries
     154                 :            :  * @enabled:    the patch is enabled (but operation may be incomplete)
     155                 :            :  * @forced:     was involved in a forced transition
     156                 :            :  * @free_work:  patch cleanup from workqueue-context
     157                 :            :  * @finish:     for waiting till it is safe to remove the patch module
     158                 :            :  */
     159                 :            : struct klp_patch {
     160                 :            :         /* external */
     161                 :            :         struct module *mod;
     162                 :            :         struct klp_object *objs;
     163                 :            :         struct klp_state *states;
     164                 :            :         bool replace;
     165                 :            : 
     166                 :            :         /* internal */
     167                 :            :         struct list_head list;
     168                 :            :         struct kobject kobj;
     169                 :            :         struct list_head obj_list;
     170                 :            :         bool enabled;
     171                 :            :         bool forced;
     172                 :            :         struct work_struct free_work;
     173                 :            :         struct completion finish;
     174                 :            : };
     175                 :            : 
     176                 :            : #define klp_for_each_object_static(patch, obj) \
     177                 :            :         for (obj = patch->objs; obj->funcs || obj->name; obj++)
     178                 :            : 
     179                 :            : #define klp_for_each_object_safe(patch, obj, tmp_obj)           \
     180                 :            :         list_for_each_entry_safe(obj, tmp_obj, &patch->obj_list, node)
     181                 :            : 
     182                 :            : #define klp_for_each_object(patch, obj) \
     183                 :            :         list_for_each_entry(obj, &patch->obj_list, node)
     184                 :            : 
     185                 :            : #define klp_for_each_func_static(obj, func) \
     186                 :            :         for (func = obj->funcs; \
     187                 :            :              func->old_name || func->new_func || func->old_sympos; \
     188                 :            :              func++)
     189                 :            : 
     190                 :            : #define klp_for_each_func_safe(obj, func, tmp_func)                     \
     191                 :            :         list_for_each_entry_safe(func, tmp_func, &obj->func_list, node)
     192                 :            : 
     193                 :            : #define klp_for_each_func(obj, func)    \
     194                 :            :         list_for_each_entry(func, &obj->func_list, node)
     195                 :            : 
     196                 :            : int klp_enable_patch(struct klp_patch *);
     197                 :            : 
     198                 :            : void arch_klp_init_object_loaded(struct klp_patch *patch,
     199                 :            :                                  struct klp_object *obj);
     200                 :            : 
     201                 :            : /* Called from the module loader during module coming/going states */
     202                 :            : int klp_module_coming(struct module *mod);
     203                 :            : void klp_module_going(struct module *mod);
     204                 :            : 
     205                 :            : void klp_copy_process(struct task_struct *child);
     206                 :            : void klp_update_patch_state(struct task_struct *task);
     207                 :            : 
     208                 :            : static inline bool klp_patch_pending(struct task_struct *task)
     209                 :            : {
     210                 :            :         return test_tsk_thread_flag(task, TIF_PATCH_PENDING);
     211                 :            : }
     212                 :            : 
     213                 :            : static inline bool klp_have_reliable_stack(void)
     214                 :            : {
     215                 :            :         return IS_ENABLED(CONFIG_STACKTRACE) &&
     216                 :            :                IS_ENABLED(CONFIG_HAVE_RELIABLE_STACKTRACE);
     217                 :            : }
     218                 :            : 
     219                 :            : typedef int (*klp_shadow_ctor_t)(void *obj,
     220                 :            :                                  void *shadow_data,
     221                 :            :                                  void *ctor_data);
     222                 :            : typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data);
     223                 :            : 
     224                 :            : void *klp_shadow_get(void *obj, unsigned long id);
     225                 :            : void *klp_shadow_alloc(void *obj, unsigned long id,
     226                 :            :                        size_t size, gfp_t gfp_flags,
     227                 :            :                        klp_shadow_ctor_t ctor, void *ctor_data);
     228                 :            : void *klp_shadow_get_or_alloc(void *obj, unsigned long id,
     229                 :            :                               size_t size, gfp_t gfp_flags,
     230                 :            :                               klp_shadow_ctor_t ctor, void *ctor_data);
     231                 :            : void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor);
     232                 :            : void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor);
     233                 :            : 
     234                 :            : struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id);
     235                 :            : struct klp_state *klp_get_prev_state(unsigned long id);
     236                 :            : 
     237                 :            : #else /* !CONFIG_LIVEPATCH */
     238                 :            : 
     239                 :        120 : static inline int klp_module_coming(struct module *mod) { return 0; }
     240                 :          0 : static inline void klp_module_going(struct module *mod) {}
     241                 :      59696 : static inline bool klp_patch_pending(struct task_struct *task) { return false; }
     242                 :          0 : static inline void klp_update_patch_state(struct task_struct *task) {}
     243                 :      14073 : static inline void klp_copy_process(struct task_struct *child) {}
     244                 :            : 
     245                 :            : #endif /* CONFIG_LIVEPATCH */
     246                 :            : 
     247                 :            : #endif /* _LINUX_LIVEPATCH_H_ */

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