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| 3 | * livepatch-sample.c - Kernel Live Patching Sample Module
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| 4 | *
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| 5 | * Copyright (C) 2014 Seth Jennings <[email protected]>
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| 6 |
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| 7 |
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| 8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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| 9 |
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| 10 | #include <linux/module.h>
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| 11 | #include <linux/kernel.h>
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| 12 | #include <linux/livepatch.h>
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| 13 |
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| 14 | |
| 15 | * This (dumb) live patch overrides the function that prints the
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| 16 | * kernel boot cmdline when /proc/cmdline is read.
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| 17 | *
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| 18 | * Example:
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| 19 | *
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| 20 | * $ cat /proc/cmdline
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| 21 | * <your cmdline>
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| 22 | *
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| 23 | * $ insmod livepatch-sample.ko
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| 24 | * $ cat /proc/cmdline
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| 25 | * this has been live patched
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| 26 | *
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| 27 | * $ echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled
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| 28 | * $ cat /proc/cmdline
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| 29 | * <your cmdline>
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| 30 |
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| 31 |
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| 32 | #include <linux/seq_file.h>
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| 33 | static int livepatch_cmdline_proc_show(struct seq_file *m, void *v)
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| 34 | {
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| 35 | seq_printf(m, "%s\n", "this has been live patched");
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| 36 | return 0;
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| 37 | }
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| 38 |
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| 39 | static struct klp_func funcs[] = {
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| 40 | {
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| 41 | .old_name = "cmdline_proc_show",
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| 42 | .new_func = livepatch_cmdline_proc_show,
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| 43 | }, { }
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| 44 | };
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| 45 |
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| 46 | static struct klp_object objs[] = {
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| 47 | {
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| 48 |
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| 49 | .funcs = funcs,
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| 50 | }, { }
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| 51 | };
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| 52 |
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| 53 | static struct klp_patch patch = {
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| 54 | .mod = THIS_MODULE,
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| 55 | .objs = objs,
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| 56 | };
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| 57 |
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| 58 | static int livepatch_init(void)
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| 59 | {
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| 60 | return klp_enable_patch(&patch);
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| 61 | }
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| 62 |
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| 63 | static void livepatch_exit(void)
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| 64 | {
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| 65 | }
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| 66 |
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| 67 | module_init(livepatch_init);
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| 68 | module_exit(livepatch_exit);
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| 69 | MODULE_LICENSE("GPL");
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| 70 | MODULE_INFO(livepatch, "Y");
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