1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Module taint unload tracking support
  4 *
  5 * Copyright (C) 2022 Aaron Tomlin
  6 */
  7
  8#include <linux/module.h>
  9#include <linux/string.h>
 10#include <linux/printk.h>
 11#include <linux/slab.h>
 12#include <linux/list.h>
 13#include <linux/debugfs.h>
 14#include <linux/rculist.h>
 15#include "internal.h"
 16
 17static LIST_HEAD(unloaded_tainted_modules);
 18
 19int try_add_tainted_module(struct module *mod)
 20{
 21	struct mod_unload_taint *mod_taint;
 22
 23	module_assert_mutex_or_preempt();
 24
 25	if (!mod->taints)
 26		goto out;
 27
 28	list_for_each_entry_rcu(mod_taint, &unloaded_tainted_modules, list,
 29				lockdep_is_held(&module_mutex)) {
 30		if (!strcmp(mod_taint->name, mod->name) &&
 31		    mod_taint->taints & mod->taints) {
 32			mod_taint->count++;
 33			goto out;
 34		}
 35	}
 36
 37	mod_taint = kmalloc(sizeof(*mod_taint), GFP_KERNEL);
 38	if (unlikely(!mod_taint))
 39		return -ENOMEM;
 40	strscpy(mod_taint->name, mod->name, MODULE_NAME_LEN);
 41	mod_taint->taints = mod->taints;
 42	list_add_rcu(&mod_taint->list, &unloaded_tainted_modules);
 43	mod_taint->count = 1;
 44out:
 45	return 0;
 46}
 47
 48void print_unloaded_tainted_modules(void)
 49{
 50	struct mod_unload_taint *mod_taint;
 51	char buf[MODULE_FLAGS_BUF_SIZE];
 52
 53	if (!list_empty(&unloaded_tainted_modules)) {
 54		printk(KERN_DEFAULT "Unloaded tainted modules:");
 55		list_for_each_entry_rcu(mod_taint, &unloaded_tainted_modules,
 56					list) {
 57			size_t l;
 58
 59			l = module_flags_taint(mod_taint->taints, buf);
 60			buf[l++] = '\0';
 61			pr_cont(" %s(%s):%llu", mod_taint->name, buf,
 62				mod_taint->count);
 63		}
 64	}
 65}
 66
 67#ifdef CONFIG_DEBUG_FS
 68static void *unloaded_tainted_modules_seq_start(struct seq_file *m, loff_t *pos)
 69	__acquires(rcu)
 70{
 71	rcu_read_lock();
 72	return seq_list_start_rcu(&unloaded_tainted_modules, *pos);
 73}
 74
 75static void *unloaded_tainted_modules_seq_next(struct seq_file *m, void *p, loff_t *pos)
 76{
 77	return seq_list_next_rcu(p, &unloaded_tainted_modules, pos);
 78}
 79
 80static void unloaded_tainted_modules_seq_stop(struct seq_file *m, void *p)
 81	__releases(rcu)
 82{
 83	rcu_read_unlock();
 84}
 85
 86static int unloaded_tainted_modules_seq_show(struct seq_file *m, void *p)
 87{
 88	struct mod_unload_taint *mod_taint;
 89	char buf[MODULE_FLAGS_BUF_SIZE];
 90	size_t l;
 91
 92	mod_taint = list_entry(p, struct mod_unload_taint, list);
 93	l = module_flags_taint(mod_taint->taints, buf);
 94	buf[l++] = '\0';
 95
 96	seq_printf(m, "%s (%s) %llu", mod_taint->name, buf, mod_taint->count);
 97	seq_puts(m, "\n");
 98
 99	return 0;
100}
101
102static const struct seq_operations unloaded_tainted_modules_seq_ops = {
103	.start = unloaded_tainted_modules_seq_start,
104	.next  = unloaded_tainted_modules_seq_next,
105	.stop  = unloaded_tainted_modules_seq_stop,
106	.show  = unloaded_tainted_modules_seq_show,
107};
108
109static int unloaded_tainted_modules_open(struct inode *inode, struct file *file)
110{
111	return seq_open(file, &unloaded_tainted_modules_seq_ops);
112}
113
114static const struct file_operations unloaded_tainted_modules_fops = {
115	.open = unloaded_tainted_modules_open,
116	.read = seq_read,
117	.llseek = seq_lseek,
118	.release = seq_release,
119};
120
121static int __init unloaded_tainted_modules_init(void)
122{
123	struct dentry *dir;
124
125	dir = debugfs_create_dir("modules", NULL);
126	debugfs_create_file("unloaded_tainted", 0444, dir, NULL,
127			    &unloaded_tainted_modules_fops);
128
129	return 0;
130}
131module_init(unloaded_tainted_modules_init);
132#endif /* CONFIG_DEBUG_FS */