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