Commit 13d1cf7e authored by Seth Jennings's avatar Seth Jennings Committed by Jiri Kosina

livepatch: samples: add sample live patching module

Add a sample live patching module.
Signed-off-by: 's avatarSeth Jennings <sjenning@redhat.com>
Reviewed-by: 's avatarMiroslav Benes <mbenes@suse.cz>
Reviewed-by: 's avatarPetr Mladek <pmladek@suse.cz>
Reviewed-by: 's avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: 's avatarJiri Kosina <jkosina@suse.cz>
parent b700e7f0
......@@ -5795,6 +5795,7 @@ F: include/linux/livepatch.h
F: arch/x86/include/asm/livepatch.h
F: arch/x86/kernel/livepatch.c
F: Documentation/ABI/testing/sysfs-kernel-livepatch
F: samples/livepatch/
L: live-patching@vger.kernel.org
LLC (802.2)
......
......@@ -63,4 +63,11 @@ config SAMPLE_RPMSG_CLIENT
to communicate with an AMP-configured remote processor over
the rpmsg bus.
config SAMPLE_LIVE_PATCHING
tristate "Build live patching sample -- loadable modules only"
depends on LIVE_PATCHING && m
help
Builds a sample live patch that replaces the procfs handler
for /proc/cmdline to print "this has been live patched".
endif # SAMPLES
# Makefile for Linux samples code
obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ \
obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \
hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/
obj-$(CONFIG_SAMPLE_LIVE_PATCHING) += livepatch-sample.o
/*
* livepatch-sample.c - Kernel Live Patching Sample Module
*
* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
*
* 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 <http://www.gnu.org/licenses/>.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/livepatch.h>
/*
* This (dumb) live patch overrides the function that prints the
* kernel boot cmdline when /proc/cmdline is read.
*
* Example:
* $ cat /proc/cmdline
* <your cmdline>
* $ insmod livepatch-sample.ko
* $ cat /proc/cmdline
* this has been live patched
* $ echo 0 > /sys/kernel/livepatch/klp_sample/enabled
* <your cmdline>
*/
#include <linux/seq_file.h>
static int livepatch_cmdline_proc_show(struct seq_file *m, void *v)
{
seq_printf(m, "%s\n", "this has been live patched");
return 0;
}
static struct klp_func funcs[] = {
{
.old_name = "cmdline_proc_show",
.new_func = livepatch_cmdline_proc_show,
}, { }
};
static struct klp_object objs[] = {
{
/* name being NULL means vmlinux */
.funcs = funcs,
}, { }
};
static struct klp_patch patch = {
.mod = THIS_MODULE,
.objs = objs,
};
static int livepatch_init(void)
{
int ret;
ret = klp_register_patch(&patch);
if (ret)
return ret;
ret = klp_enable_patch(&patch);
if (ret) {
WARN_ON(klp_unregister_patch(&patch));
return ret;
}
return 0;
}
static void livepatch_exit(void)
{
WARN_ON(klp_disable_patch(&patch));
WARN_ON(klp_unregister_patch(&patch));
}
module_init(livepatch_init);
module_exit(livepatch_exit);
MODULE_LICENSE("GPL");
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