235 строки
6.9 KiB
C
235 строки
6.9 KiB
C
/*
|
|
* Copyright (C) 2017 Joe Lawrence <joe.lawrence@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/>.
|
|
*/
|
|
|
|
/*
|
|
* livepatch-callbacks-demo.c - (un)patching callbacks livepatch demo
|
|
*
|
|
*
|
|
* Purpose
|
|
* -------
|
|
*
|
|
* Demonstration of registering livepatch (un)patching callbacks.
|
|
*
|
|
*
|
|
* Usage
|
|
* -----
|
|
*
|
|
* Step 1 - load the simple module
|
|
*
|
|
* insmod samples/livepatch/livepatch-callbacks-mod.ko
|
|
*
|
|
*
|
|
* Step 2 - load the demonstration livepatch (with callbacks)
|
|
*
|
|
* insmod samples/livepatch/livepatch-callbacks-demo.ko
|
|
*
|
|
*
|
|
* Step 3 - cleanup
|
|
*
|
|
* echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
|
|
* rmmod livepatch_callbacks_demo
|
|
* rmmod livepatch_callbacks_mod
|
|
*
|
|
* Watch dmesg output to see livepatch enablement, callback execution
|
|
* and patching operations for both vmlinux and module targets.
|
|
*
|
|
* NOTE: swap the insmod order of livepatch-callbacks-mod.ko and
|
|
* livepatch-callbacks-demo.ko to observe what happens when a
|
|
* target module is loaded after a livepatch with callbacks.
|
|
*
|
|
* NOTE: 'pre_patch_ret' is a module parameter that sets the pre-patch
|
|
* callback return status. Try setting up a non-zero status
|
|
* such as -19 (-ENODEV):
|
|
*
|
|
* # Load demo livepatch, vmlinux is patched
|
|
* insmod samples/livepatch/livepatch-callbacks-demo.ko
|
|
*
|
|
* # Setup next pre-patch callback to return -ENODEV
|
|
* echo -19 > /sys/module/livepatch_callbacks_demo/parameters/pre_patch_ret
|
|
*
|
|
* # Module loader refuses to load the target module
|
|
* insmod samples/livepatch/livepatch-callbacks-mod.ko
|
|
* insmod: ERROR: could not insert module samples/livepatch/livepatch-callbacks-mod.ko: No such device
|
|
*
|
|
* NOTE: There is a second target module,
|
|
* livepatch-callbacks-busymod.ko, available for experimenting
|
|
* with livepatch (un)patch callbacks. This module contains
|
|
* a 'sleep_secs' parameter that parks the module on one of the
|
|
* functions that the livepatch demo module wants to patch.
|
|
* Modifying this value and tweaking the order of module loads can
|
|
* effectively demonstrate stalled patch transitions:
|
|
*
|
|
* # Load a target module, let it park on 'busymod_work_func' for
|
|
* # thirty seconds
|
|
* insmod samples/livepatch/livepatch-callbacks-busymod.ko sleep_secs=30
|
|
*
|
|
* # Meanwhile load the livepatch
|
|
* insmod samples/livepatch/livepatch-callbacks-demo.ko
|
|
*
|
|
* # ... then load and unload another target module while the
|
|
* # transition is in progress
|
|
* insmod samples/livepatch/livepatch-callbacks-mod.ko
|
|
* rmmod samples/livepatch/livepatch-callbacks-mod.ko
|
|
*
|
|
* # Finally cleanup
|
|
* echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
|
|
* rmmod samples/livepatch/livepatch-callbacks-demo.ko
|
|
*/
|
|
|
|
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/livepatch.h>
|
|
|
|
static int pre_patch_ret;
|
|
module_param(pre_patch_ret, int, 0644);
|
|
MODULE_PARM_DESC(pre_patch_ret, "pre_patch_ret (default=0)");
|
|
|
|
static const char *const module_state[] = {
|
|
[MODULE_STATE_LIVE] = "[MODULE_STATE_LIVE] Normal state",
|
|
[MODULE_STATE_COMING] = "[MODULE_STATE_COMING] Full formed, running module_init",
|
|
[MODULE_STATE_GOING] = "[MODULE_STATE_GOING] Going away",
|
|
[MODULE_STATE_UNFORMED] = "[MODULE_STATE_UNFORMED] Still setting it up",
|
|
};
|
|
|
|
static void callback_info(const char *callback, struct klp_object *obj)
|
|
{
|
|
if (obj->mod)
|
|
pr_info("%s: %s -> %s\n", callback, obj->mod->name,
|
|
module_state[obj->mod->state]);
|
|
else
|
|
pr_info("%s: vmlinux\n", callback);
|
|
}
|
|
|
|
/* Executed on object patching (ie, patch enablement) */
|
|
static int pre_patch_callback(struct klp_object *obj)
|
|
{
|
|
callback_info(__func__, obj);
|
|
return pre_patch_ret;
|
|
}
|
|
|
|
/* Executed on object unpatching (ie, patch disablement) */
|
|
static void post_patch_callback(struct klp_object *obj)
|
|
{
|
|
callback_info(__func__, obj);
|
|
}
|
|
|
|
/* Executed on object unpatching (ie, patch disablement) */
|
|
static void pre_unpatch_callback(struct klp_object *obj)
|
|
{
|
|
callback_info(__func__, obj);
|
|
}
|
|
|
|
/* Executed on object unpatching (ie, patch disablement) */
|
|
static void post_unpatch_callback(struct klp_object *obj)
|
|
{
|
|
callback_info(__func__, obj);
|
|
}
|
|
|
|
static void patched_work_func(struct work_struct *work)
|
|
{
|
|
pr_info("%s\n", __func__);
|
|
}
|
|
|
|
static struct klp_func no_funcs[] = {
|
|
{ }
|
|
};
|
|
|
|
static struct klp_func busymod_funcs[] = {
|
|
{
|
|
.old_name = "busymod_work_func",
|
|
.new_func = patched_work_func,
|
|
}, { }
|
|
};
|
|
|
|
static struct klp_object objs[] = {
|
|
{
|
|
.name = NULL, /* vmlinux */
|
|
.funcs = no_funcs,
|
|
.callbacks = {
|
|
.pre_patch = pre_patch_callback,
|
|
.post_patch = post_patch_callback,
|
|
.pre_unpatch = pre_unpatch_callback,
|
|
.post_unpatch = post_unpatch_callback,
|
|
},
|
|
}, {
|
|
.name = "livepatch_callbacks_mod",
|
|
.funcs = no_funcs,
|
|
.callbacks = {
|
|
.pre_patch = pre_patch_callback,
|
|
.post_patch = post_patch_callback,
|
|
.pre_unpatch = pre_unpatch_callback,
|
|
.post_unpatch = post_unpatch_callback,
|
|
},
|
|
}, {
|
|
.name = "livepatch_callbacks_busymod",
|
|
.funcs = busymod_funcs,
|
|
.callbacks = {
|
|
.pre_patch = pre_patch_callback,
|
|
.post_patch = post_patch_callback,
|
|
.pre_unpatch = pre_unpatch_callback,
|
|
.post_unpatch = post_unpatch_callback,
|
|
},
|
|
}, { }
|
|
};
|
|
|
|
static struct klp_patch patch = {
|
|
.mod = THIS_MODULE,
|
|
.objs = objs,
|
|
};
|
|
|
|
static int livepatch_callbacks_demo_init(void)
|
|
{
|
|
int ret;
|
|
|
|
if (!klp_have_reliable_stack() && !patch.immediate) {
|
|
/*
|
|
* WARNING: Be very careful when using 'patch.immediate' in
|
|
* your patches. It's ok to use it for simple patches like
|
|
* this, but for more complex patches which change function
|
|
* semantics, locking semantics, or data structures, it may not
|
|
* be safe. Use of this option will also prevent removal of
|
|
* the patch.
|
|
*
|
|
* See Documentation/livepatch/livepatch.txt for more details.
|
|
*/
|
|
patch.immediate = true;
|
|
pr_notice("The consistency model isn't supported for your architecture. Bypassing safety mechanisms and applying the patch immediately.\n");
|
|
}
|
|
|
|
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_callbacks_demo_exit(void)
|
|
{
|
|
WARN_ON(klp_unregister_patch(&patch));
|
|
}
|
|
|
|
module_init(livepatch_callbacks_demo_init);
|
|
module_exit(livepatch_callbacks_demo_exit);
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_INFO(livepatch, "Y");
|