diff options
Diffstat (limited to 'samples')
| -rw-r--r-- | samples/Kconfig | 7 | ||||
| -rw-r--r-- | samples/Makefile | 2 | ||||
| -rw-r--r-- | samples/livepatch/Makefile | 1 | ||||
| -rw-r--r-- | samples/livepatch/livepatch-sample.c | 91 |
4 files changed, 100 insertions, 1 deletions
diff --git a/samples/Kconfig b/samples/Kconfig index 6181c2cc9ca0..224ebb46bed5 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -63,4 +63,11 @@ config SAMPLE_RPMSG_CLIENT to communicate with an AMP-configured remote processor over the rpmsg bus. +config SAMPLE_LIVEPATCH + tristate "Build live patching sample -- loadable modules only" + depends on LIVEPATCH && m + help + Builds a sample live patch that replaces the procfs handler + for /proc/cmdline to print "this has been live patched". + endif # SAMPLES diff --git a/samples/Makefile b/samples/Makefile index 1a60c62e2045..f00257bcc5a7 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -1,4 +1,4 @@ # 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/ diff --git a/samples/livepatch/Makefile b/samples/livepatch/Makefile new file mode 100644 index 000000000000..10319d7ea0b1 --- /dev/null +++ b/samples/livepatch/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-sample.o diff --git a/samples/livepatch/livepatch-sample.c b/samples/livepatch/livepatch-sample.c new file mode 100644 index 000000000000..fb8c8614e728 --- /dev/null +++ b/samples/livepatch/livepatch-sample.c @@ -0,0 +1,91 @@ +/* + * 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/livepatch_sample/enabled + * $ cat /proc/cmdline + * <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"); |