LXR linux/lib/livepatch/test_klp

   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (C) 2019 SUSE
   3
   4#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   5
   6#include <linux/slab.h>
   7#include <linux/module.h>
   8#include <linux/kernel.h>
   9#include <linux/printk.h>
  10#include <linux/livepatch.h>
  11
  12#define CONSOLE_LOGLEVEL_STATE 1
  13/* Version 1 does not support migration. */
  14#define CONSOLE_LOGLEVEL_STATE_VERSION 1
  15
  16static const char *const module_state[] = {
  17        [MODULE_STATE_LIVE]     = "[MODULE_STATE_LIVE] Normal state",
  18        [MODULE_STATE_COMING]   = "[MODULE_STATE_COMING] Full formed, running module_init",
  19        [MODULE_STATE_GOING]    = "[MODULE_STATE_GOING] Going away",
  20        [MODULE_STATE_UNFORMED] = "[MODULE_STATE_UNFORMED] Still setting it up",
  21};
  22
  23static void callback_info(const char *callback, struct klp_object *obj)
  24{
  25        if (obj->mod)
  26                pr_info("%s: %s -> %s\n", callback, obj->mod->name,
  27                        module_state[obj->mod->state]);
  28        else
  29                pr_info("%s: vmlinux\n", callback);
  30}
  31
  32static struct klp_patch patch;
  33
  34static int allocate_loglevel_state(void)
  35{
  36        struct klp_state *loglevel_state;
  37
  38        loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
  39        if (!loglevel_state)
  40                return -EINVAL;
  41
  42        loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL);
  43        if (!loglevel_state->data)
  44                return -ENOMEM;
  45
  46        pr_info("%s: allocating space to store console_loglevel\n",
  47                __func__);
  48        return 0;
  49}
  50
  51static void fix_console_loglevel(void)
  52{
  53        struct klp_state *loglevel_state;
  54
  55        loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
  56        if (!loglevel_state)
  57                return;
  58
  59        pr_info("%s: fixing console_loglevel\n", __func__);
  60        *(int *)loglevel_state->data = console_loglevel;
  61        console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
  62}
  63
  64static void restore_console_loglevel(void)
  65{
  66        struct klp_state *loglevel_state;
  67
  68        loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
  69        if (!loglevel_state)
  70                return;
  71
  72        pr_info("%s: restoring console_loglevel\n", __func__);
  73        console_loglevel = *(int *)loglevel_state->data;
  74}
  75
  76static void free_loglevel_state(void)
  77{
  78        struct klp_state *loglevel_state;
  79
  80        loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
  81        if (!loglevel_state)
  82                return;
  83
  84        pr_info("%s: freeing space for the stored console_loglevel\n",
  85                __func__);
  86        kfree(loglevel_state->data);
  87}
  88
  89/* Executed on object patching (ie, patch enablement) */
  90static int pre_patch_callback(struct klp_object *obj)
  91{
  92        callback_info(__func__, obj);
  93        return allocate_loglevel_state();
  94}
  95
  96/* Executed on object unpatching (ie, patch disablement) */
  97static void post_patch_callback(struct klp_object *obj)
  98{
  99        callback_info(__func__, obj);
 100        fix_console_loglevel();
 101}
 102
 103/* Executed on object unpatching (ie, patch disablement) */
 104static void pre_unpatch_callback(struct klp_object *obj)
 105{
 106        callback_info(__func__, obj);
 107        restore_console_loglevel();
 108}
 109
 110/* Executed on object unpatching (ie, patch disablement) */
 111static void post_unpatch_callback(struct klp_object *obj)
 112{
 113        callback_info(__func__, obj);
 114        free_loglevel_state();
 115}
 116
 117static struct klp_func no_funcs[] = {
 118        {}
 119};
 120
 121static struct klp_object objs[] = {
 122        {
 123                .name = NULL,   /* vmlinux */
 124                .funcs = no_funcs,
 125                .callbacks = {
 126                        .pre_patch = pre_patch_callback,
 127                        .post_patch = post_patch_callback,
 128                        .pre_unpatch = pre_unpatch_callback,
 129                        .post_unpatch = post_unpatch_callback,
 130                },
 131        }, { }
 132};
 133
 134static struct klp_state states[] = {
 135        {
 136                .id = CONSOLE_LOGLEVEL_STATE,
 137                .version = CONSOLE_LOGLEVEL_STATE_VERSION,
 138        }, { }
 139};
 140
 141static struct klp_patch patch = {
 142        .mod = THIS_MODULE,
 143        .objs = objs,
 144        .states = states,
 145        .replace = true,
 146};
 147
 148static int test_klp_callbacks_demo_init(void)
 149{
 150        return klp_enable_patch(&patch);
 151}
 152
 153static void test_klp_callbacks_demo_exit(void)
 154{
 155}
 156
 157module_init(test_klp_callbacks_demo_init);
 158module_exit(test_klp_callbacks_demo_exit);
 159MODULE_LICENSE("GPL");
 160MODULE_INFO(livepatch, "Y");
 161MODULE_AUTHOR("Petr Mladek <pmladek@suse.com>");
 162MODULE_DESCRIPTION("Livepatch test: system state modification");
 163