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
17 static LIST_HEAD(unloaded_tainted_modules);
18
try_add_tainted_module(struct module * mod)19 int 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;
44 out:
45 return 0;
46 }
47
print_unloaded_tainted_modules(void)48 void 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
unloaded_tainted_modules_seq_start(struct seq_file * m,loff_t * pos)68 static 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
unloaded_tainted_modules_seq_next(struct seq_file * m,void * p,loff_t * pos)75 static 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
unloaded_tainted_modules_seq_stop(struct seq_file * m,void * p)80 static void unloaded_tainted_modules_seq_stop(struct seq_file *m, void *p)
81 __releases(rcu)
82 {
83 rcu_read_unlock();
84 }
85
unloaded_tainted_modules_seq_show(struct seq_file * m,void * p)86 static 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
102 static 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
unloaded_tainted_modules_open(struct inode * inode,struct file * file)109 static int unloaded_tainted_modules_open(struct inode *inode, struct file *file)
110 {
111 return seq_open(file, &unloaded_tainted_modules_seq_ops);
112 }
113
114 static 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
unloaded_tainted_modules_init(void)121 static 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 }
131 module_init(unloaded_tainted_modules_init);
132 #endif /* CONFIG_DEBUG_FS */
133