163 lines
3.8 KiB
C
163 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2019 SUSE
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/printk.h>
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#include <linux/livepatch.h>
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#define CONSOLE_LOGLEVEL_STATE 1
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/* Version 1 does not support migration. */
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#define CONSOLE_LOGLEVEL_STATE_VERSION 1
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static const char *const module_state[] = {
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[MODULE_STATE_LIVE] = "[MODULE_STATE_LIVE] Normal state",
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[MODULE_STATE_COMING] = "[MODULE_STATE_COMING] Full formed, running module_init",
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[MODULE_STATE_GOING] = "[MODULE_STATE_GOING] Going away",
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[MODULE_STATE_UNFORMED] = "[MODULE_STATE_UNFORMED] Still setting it up",
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};
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static void callback_info(const char *callback, struct klp_object *obj)
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{
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if (obj->mod)
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pr_info("%s: %s -> %s\n", callback, obj->mod->name,
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module_state[obj->mod->state]);
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else
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pr_info("%s: vmlinux\n", callback);
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}
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static struct klp_patch patch;
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static int allocate_loglevel_state(void)
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{
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struct klp_state *loglevel_state;
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loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
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if (!loglevel_state)
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return -EINVAL;
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loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL);
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if (!loglevel_state->data)
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return -ENOMEM;
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pr_info("%s: allocating space to store console_loglevel\n",
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__func__);
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return 0;
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}
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static void fix_console_loglevel(void)
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{
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struct klp_state *loglevel_state;
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loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
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if (!loglevel_state)
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return;
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pr_info("%s: fixing console_loglevel\n", __func__);
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*(int *)loglevel_state->data = console_loglevel;
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console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
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}
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static void restore_console_loglevel(void)
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{
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struct klp_state *loglevel_state;
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loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
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if (!loglevel_state)
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return;
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pr_info("%s: restoring console_loglevel\n", __func__);
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console_loglevel = *(int *)loglevel_state->data;
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}
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static void free_loglevel_state(void)
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{
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struct klp_state *loglevel_state;
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loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
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if (!loglevel_state)
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return;
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pr_info("%s: freeing space for the stored console_loglevel\n",
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__func__);
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kfree(loglevel_state->data);
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}
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/* Executed on object patching (ie, patch enablement) */
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static int pre_patch_callback(struct klp_object *obj)
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{
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callback_info(__func__, obj);
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return allocate_loglevel_state();
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}
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/* Executed on object unpatching (ie, patch disablement) */
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static void post_patch_callback(struct klp_object *obj)
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{
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callback_info(__func__, obj);
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fix_console_loglevel();
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}
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/* Executed on object unpatching (ie, patch disablement) */
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static void pre_unpatch_callback(struct klp_object *obj)
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{
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callback_info(__func__, obj);
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restore_console_loglevel();
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}
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/* Executed on object unpatching (ie, patch disablement) */
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static void post_unpatch_callback(struct klp_object *obj)
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{
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callback_info(__func__, obj);
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free_loglevel_state();
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}
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static struct klp_func no_funcs[] = {
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{}
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};
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static struct klp_object objs[] = {
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{
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.name = NULL, /* vmlinux */
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.funcs = no_funcs,
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.callbacks = {
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.pre_patch = pre_patch_callback,
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.post_patch = post_patch_callback,
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.pre_unpatch = pre_unpatch_callback,
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.post_unpatch = post_unpatch_callback,
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},
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}, { }
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};
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static struct klp_state states[] = {
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{
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.id = CONSOLE_LOGLEVEL_STATE,
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.version = CONSOLE_LOGLEVEL_STATE_VERSION,
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}, { }
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};
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static struct klp_patch patch = {
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.mod = THIS_MODULE,
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.objs = objs,
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.states = states,
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.replace = true,
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};
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static int test_klp_callbacks_demo_init(void)
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{
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return klp_enable_patch(&patch);
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}
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static void test_klp_callbacks_demo_exit(void)
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{
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}
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module_init(test_klp_callbacks_demo_init);
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module_exit(test_klp_callbacks_demo_exit);
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MODULE_LICENSE("GPL");
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MODULE_INFO(livepatch, "Y");
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MODULE_AUTHOR("Petr Mladek <pmladek@suse.com>");
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MODULE_DESCRIPTION("Livepatch test: system state modification");
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