kernel/module/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
  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 */