mirror of
https://github.com/dynup/kpatch
synced 2025-04-04 23:29:23 +00:00
b7a2862f90
Currently the patch module calls kpatch_unregister in the patch module exit path. If the activeness safety check fails in kpatch_unregister, it's too late for the patch module to stop exiting, so all it can do is panic. Prevent this scenario by requiring the user to disable the patch module via sysfs before allowing the module to be unloaded. The sysfs write will fail if the activeness safety check fails. An rmmod will fail if the patch is still enabled. Also add support for this new unloading model in "kpatch unload".
128 lines
3.1 KiB
C
128 lines
3.1 KiB
C
/*
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* Copyright (C) 2013-2014 Josh Poimboeuf <jpoimboe@redhat.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA,
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* 02110-1301, USA.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/printk.h>
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#include <linux/slab.h>
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#include "kpatch.h"
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#include "kpatch-patch.h"
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extern char __kpatch_patches, __kpatch_patches_end;
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static struct kpatch_module kpmod;
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static struct kobject *patch_kobj;
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static ssize_t patch_enabled_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", kpmod.enabled);
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}
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static ssize_t patch_enabled_store(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf,
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size_t count)
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{
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int ret;
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unsigned long val;
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/* only disabling is supported */
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if (!kpmod.enabled)
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return -EINVAL;
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ret = kstrtoul(buf, 10, &val);
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if (ret)
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return ret;
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val = !!val;
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/* only disabling is supported */
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if (val)
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return -EINVAL;
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ret = kpatch_unregister(&kpmod);
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if (ret)
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return ret;
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return count;
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}
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static struct kobj_attribute patch_enabled_attr =
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__ATTR(enabled, 0644, patch_enabled_show, patch_enabled_store);
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static int __init patch_init(void)
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{
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struct kpatch_patch *patches;
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int i, ret;
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patches = (struct kpatch_patch *)&__kpatch_patches;
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kpmod.mod = THIS_MODULE;
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kpmod.num_funcs = (&__kpatch_patches_end - &__kpatch_patches) /
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sizeof(*patches);
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kpmod.funcs = kmalloc(kpmod.num_funcs * sizeof(struct kpatch_func),
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GFP_KERNEL);
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if (!kpmod.funcs)
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return -ENOMEM;
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for (i = 0; i < kpmod.num_funcs; i++) {
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kpmod.funcs[i].old_addr = patches[i].old_addr;
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kpmod.funcs[i].old_size = patches[i].old_size;
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kpmod.funcs[i].new_addr = patches[i].new_addr;
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kpmod.funcs[i].new_size = patches[i].new_size;
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}
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patch_kobj = kobject_create_and_add(THIS_MODULE->name,
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kpatch_patches_kobj);
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if (!patch_kobj) {
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ret = -ENOMEM;
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goto err_free;
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}
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ret = sysfs_create_file(patch_kobj, &patch_enabled_attr.attr);
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if (ret)
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goto err_put;
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ret = kpatch_register(&kpmod);
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if (ret)
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goto err_sysfs;
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return 0;
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err_sysfs:
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sysfs_remove_file(patch_kobj, &patch_enabled_attr.attr);
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err_put:
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kobject_put(patch_kobj);
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err_free:
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kfree(kpmod.funcs);
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return ret;
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}
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static void __exit patch_exit(void)
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{
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WARN_ON(kpmod.enabled);
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sysfs_remove_file(patch_kobj, &patch_enabled_attr.attr);
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kobject_put(patch_kobj);
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kfree(kpmod.funcs);
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}
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module_init(patch_init);
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module_exit(patch_exit);
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MODULE_LICENSE("GPL");
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