forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
132 lines
2.9 KiB
132 lines
2.9 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
|
/* |
|
* Copyright (C) 2017 Joe Lawrence <[email protected]> |
|
*/ |
|
|
|
/* |
|
* 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; |
|
|
|
kfree(*shadow_leak); |
|
pr_info("%s: dummy @ %p, prevented leak @ %p\n", |
|
__func__, d, *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_LICENSE("GPL"); |
|
MODULE_INFO(livepatch, "Y");
|
|
|