tracking.c

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