// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* livepatch-sample.c - Kernel Live Patching Sample Module
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*
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* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/livepatch.h>
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/*
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* This (dumb) live patch overrides the function that prints the
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* kernel boot cmdline when /proc/cmdline is read.
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*
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* Example:
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*
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* $ cat /proc/cmdline
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* <your cmdline>
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*
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* $ insmod livepatch-sample.ko
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* $ cat /proc/cmdline
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* this has been live patched
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*
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* $ echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled
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* $ cat /proc/cmdline
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* <your cmdline>
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*/
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#include <linux/seq_file.h>
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static int livepatch_cmdline_proc_show(struct seq_file *m, void *v)
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{
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seq_printf(m, "%s\n", "this has been live patched");
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return 0;
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}
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static struct klp_func funcs[] = {
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{
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.old_name = "cmdline_proc_show",
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.new_func = livepatch_cmdline_proc_show,
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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 being NULL means vmlinux */
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.funcs = funcs,
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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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};
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static int livepatch_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 livepatch_exit(void)
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{
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}
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module_init(livepatch_init);
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module_exit(livepatch_exit);
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MODULE_LICENSE("GPL");
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MODULE_INFO(livepatch, "Y");
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