linux/kernel/module/tracking.c
Aaron Tomlin 47cc75aa92 module: tracking: Keep a record of tainted unloaded modules only
This ensures that no module record/or entry is added to the
unloaded_tainted_modules list if it does not carry a taint.

Reported-by: Alexey Dobriyan <adobriyan@gmail.com>
Fixes: 99bd995655 ("module: Introduce module unload taint tracking")
Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-10-10 12:16:19 -07:00

133 lines
3.2 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Module taint unload tracking support
*
* Copyright (C) 2022 Aaron Tomlin
*/
#include <linux/module.h>
#include <linux/string.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/debugfs.h>
#include <linux/rculist.h>
#include "internal.h"
static LIST_HEAD(unloaded_tainted_modules);
int try_add_tainted_module(struct module *mod)
{
struct mod_unload_taint *mod_taint;
module_assert_mutex_or_preempt();
if (!mod->taints)
goto out;
list_for_each_entry_rcu(mod_taint, &unloaded_tainted_modules, list,
lockdep_is_held(&module_mutex)) {
if (!strcmp(mod_taint->name, mod->name) &&
mod_taint->taints & mod->taints) {
mod_taint->count++;
goto out;
}
}
mod_taint = kmalloc(sizeof(*mod_taint), GFP_KERNEL);
if (unlikely(!mod_taint))
return -ENOMEM;
strscpy(mod_taint->name, mod->name, MODULE_NAME_LEN);
mod_taint->taints = mod->taints;
list_add_rcu(&mod_taint->list, &unloaded_tainted_modules);
mod_taint->count = 1;
out:
return 0;
}
void print_unloaded_tainted_modules(void)
{
struct mod_unload_taint *mod_taint;
char buf[MODULE_FLAGS_BUF_SIZE];
if (!list_empty(&unloaded_tainted_modules)) {
printk(KERN_DEFAULT "Unloaded tainted modules:");
list_for_each_entry_rcu(mod_taint, &unloaded_tainted_modules,
list) {
size_t l;
l = module_flags_taint(mod_taint->taints, buf);
buf[l++] = '\0';
pr_cont(" %s(%s):%llu", mod_taint->name, buf,
mod_taint->count);
}
}
}
#ifdef CONFIG_DEBUG_FS
static void *unloaded_tainted_modules_seq_start(struct seq_file *m, loff_t *pos)
__acquires(rcu)
{
rcu_read_lock();
return seq_list_start_rcu(&unloaded_tainted_modules, *pos);
}
static void *unloaded_tainted_modules_seq_next(struct seq_file *m, void *p, loff_t *pos)
{
return seq_list_next_rcu(p, &unloaded_tainted_modules, pos);
}
static void unloaded_tainted_modules_seq_stop(struct seq_file *m, void *p)
__releases(rcu)
{
rcu_read_unlock();
}
static int unloaded_tainted_modules_seq_show(struct seq_file *m, void *p)
{
struct mod_unload_taint *mod_taint;
char buf[MODULE_FLAGS_BUF_SIZE];
size_t l;
mod_taint = list_entry(p, struct mod_unload_taint, list);
l = module_flags_taint(mod_taint->taints, buf);
buf[l++] = '\0';
seq_printf(m, "%s (%s) %llu", mod_taint->name, buf, mod_taint->count);
seq_puts(m, "\n");
return 0;
}
static const struct seq_operations unloaded_tainted_modules_seq_ops = {
.start = unloaded_tainted_modules_seq_start,
.next = unloaded_tainted_modules_seq_next,
.stop = unloaded_tainted_modules_seq_stop,
.show = unloaded_tainted_modules_seq_show,
};
static int unloaded_tainted_modules_open(struct inode *inode, struct file *file)
{
return seq_open(file, &unloaded_tainted_modules_seq_ops);
}
static const struct file_operations unloaded_tainted_modules_fops = {
.open = unloaded_tainted_modules_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init unloaded_tainted_modules_init(void)
{
struct dentry *dir;
dir = debugfs_create_dir("modules", NULL);
debugfs_create_file("unloaded_tainted", 0444, dir, NULL,
&unloaded_tainted_modules_fops);
return 0;
}
module_init(unloaded_tainted_modules_init);
#endif /* CONFIG_DEBUG_FS */