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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134// SPDX-License-Identifier: GPL-2.0-or-later/* * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com> */
/* * livepatch-shadow-fix2.c - Shadow variables, livepatch demo * * Purpose * ------- * * Adds functionality to livepatch-shadow-mod's in-flight data * structures through a shadow variable. The livepatch patches a * routine that periodically inspects data structures, incrementing a * per-data-structure counter, creating the counter if needed. * * * Usage * ----- * * This module is not intended to be standalone. See the "Usage" * section of livepatch-shadow-mod.c. */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>#include <linux/kernel.h>#include <linux/livepatch.h>#include <linux/slab.h>
/* Shadow variable enums */#define SV_LEAK 1#define SV_COUNTER 2
struct dummy { struct list_head list; unsigned long jiffies_expire;};
static bool livepatch_fix2_dummy_check(struct dummy *d, unsigned long jiffies){ int *shadow_count;
/* * Patch: handle in-flight dummy structures, if they do not * already have a SV_COUNTER shadow variable, then attach a * new one. */ shadow_count = klp_shadow_get_or_alloc(d, SV_COUNTER, sizeof(*shadow_count), GFP_NOWAIT, NULL, NULL); if (shadow_count) *shadow_count += 1;
return time_after(jiffies, d->jiffies_expire);}
static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data){ void *d = obj; int **shadow_leak = shadow_data;
pr_info("%s: dummy @ %p, prevented leak @ %p\n", __func__, d, *shadow_leak); kfree(*shadow_leak);}
static void livepatch_fix2_dummy_free(struct dummy *d){ int **shadow_leak; int *shadow_count;
/* Patch: copy the memory leak patch from the fix1 module. */ shadow_leak = klp_shadow_get(d, SV_LEAK); if (shadow_leak) klp_shadow_free(d, SV_LEAK, livepatch_fix2_dummy_leak_dtor); else pr_info("%s: dummy @ %p leaked!\n", __func__, d);
/* * Patch: fetch the SV_COUNTER shadow variable and display * the final count. Detach the shadow variable. */ shadow_count = klp_shadow_get(d, SV_COUNTER); if (shadow_count) { pr_info("%s: dummy @ %p, check counter = %d\n", __func__, d, *shadow_count); klp_shadow_free(d, SV_COUNTER, NULL); }
kfree(d);}
static struct klp_func funcs[] = { { .old_name = "dummy_check", .new_func = livepatch_fix2_dummy_check, }, { .old_name = "dummy_free", .new_func = livepatch_fix2_dummy_free, }, { }};
static struct klp_object objs[] = { { .name = "livepatch_shadow_mod", .funcs = funcs, }, { }};
static struct klp_patch patch = { .mod = THIS_MODULE, .objs = objs,};
static int livepatch_shadow_fix2_init(void){ return klp_enable_patch(&patch);}
static void livepatch_shadow_fix2_exit(void){ /* Cleanup any existing SV_COUNTER shadow variables */ klp_shadow_free_all(SV_COUNTER, NULL);}
module_init(livepatch_shadow_fix2_init);module_exit(livepatch_shadow_fix2_exit);MODULE_DESCRIPTION("Live patching demo for shadow variables");MODULE_LICENSE("GPL");MODULE_INFO(livepatch, "Y");