1 // SPDX-License-Identifier: GPL-2.0
2 // error-inject.c: Function-level error injection table
3 #include <linux/error-injection.h>
4 #include <linux/debugfs.h>
5 #include <linux/kallsyms.h>
6 #include <linux/kprobes.h>
7 #include <linux/module.h>
8 #include <linux/mutex.h>
9 #include <linux/list.h>
10 #include <linux/slab.h>
12 /* Whitelist of symbols that can be overridden for error injection. */
13 static LIST_HEAD(error_injection_list);
14 static DEFINE_MUTEX(ei_mutex);
16 struct list_head list;
17 unsigned long start_addr;
18 unsigned long end_addr;
23 bool within_error_injection_list(unsigned long addr)
28 mutex_lock(&ei_mutex);
29 list_for_each_entry(ent, &error_injection_list, list) {
30 if (addr >= ent->start_addr && addr < ent->end_addr) {
35 mutex_unlock(&ei_mutex);
39 int get_injectable_error_type(unsigned long addr)
43 list_for_each_entry(ent, &error_injection_list, list) {
44 if (addr >= ent->start_addr && addr < ent->end_addr)
51 * Lookup and populate the error_injection_list.
53 * For safety reasons we only allow certain functions to be overridden with
54 * bpf_error_injection, so we need to populate the list of the symbols that have
55 * been marked as safe for overriding.
57 static void populate_error_injection_list(struct error_injection_entry *start,
58 struct error_injection_entry *end,
61 struct error_injection_entry *iter;
63 unsigned long entry, offset = 0, size = 0;
65 mutex_lock(&ei_mutex);
66 for (iter = start; iter < end; iter++) {
67 entry = arch_deref_entry_point((void *)iter->addr);
69 if (!kernel_text_address(entry) ||
70 !kallsyms_lookup_size_offset(entry, &size, &offset)) {
71 pr_err("Failed to find error inject entry at %p\n",
76 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
79 ent->start_addr = entry;
80 ent->end_addr = entry + size;
81 ent->etype = iter->etype;
83 INIT_LIST_HEAD(&ent->list);
84 list_add_tail(&ent->list, &error_injection_list);
86 mutex_unlock(&ei_mutex);
89 /* Markers of the _error_inject_whitelist section */
90 extern struct error_injection_entry __start_error_injection_whitelist[];
91 extern struct error_injection_entry __stop_error_injection_whitelist[];
93 static void __init populate_kernel_ei_list(void)
95 populate_error_injection_list(__start_error_injection_whitelist,
96 __stop_error_injection_whitelist,
100 #ifdef CONFIG_MODULES
101 static void module_load_ei_list(struct module *mod)
103 if (!mod->num_ei_funcs)
106 populate_error_injection_list(mod->ei_funcs,
107 mod->ei_funcs + mod->num_ei_funcs, mod);
110 static void module_unload_ei_list(struct module *mod)
112 struct ei_entry *ent, *n;
114 if (!mod->num_ei_funcs)
117 mutex_lock(&ei_mutex);
118 list_for_each_entry_safe(ent, n, &error_injection_list, list) {
119 if (ent->priv == mod) {
120 list_del_init(&ent->list);
124 mutex_unlock(&ei_mutex);
127 /* Module notifier call back, checking error injection table on the module */
128 static int ei_module_callback(struct notifier_block *nb,
129 unsigned long val, void *data)
131 struct module *mod = data;
133 if (val == MODULE_STATE_COMING)
134 module_load_ei_list(mod);
135 else if (val == MODULE_STATE_GOING)
136 module_unload_ei_list(mod);
141 static struct notifier_block ei_module_nb = {
142 .notifier_call = ei_module_callback,
146 static __init int module_ei_init(void)
148 return register_module_notifier(&ei_module_nb);
150 #else /* !CONFIG_MODULES */
151 #define module_ei_init() (0)
155 * error_injection/whitelist -- shows which functions can be overridden for
158 static void *ei_seq_start(struct seq_file *m, loff_t *pos)
160 mutex_lock(&ei_mutex);
161 return seq_list_start(&error_injection_list, *pos);
164 static void ei_seq_stop(struct seq_file *m, void *v)
166 mutex_unlock(&ei_mutex);
169 static void *ei_seq_next(struct seq_file *m, void *v, loff_t *pos)
171 return seq_list_next(v, &error_injection_list, pos);
174 static const char *error_type_string(int etype)
181 case EI_ETYPE_ERRNO_NULL:
188 static int ei_seq_show(struct seq_file *m, void *v)
190 struct ei_entry *ent = list_entry(v, struct ei_entry, list);
192 seq_printf(m, "%ps\t%s\n", (void *)ent->start_addr,
193 error_type_string(ent->etype));
197 static const struct seq_operations ei_seq_ops = {
198 .start = ei_seq_start,
204 static int ei_open(struct inode *inode, struct file *filp)
206 return seq_open(filp, &ei_seq_ops);
209 static const struct file_operations debugfs_ei_ops = {
213 .release = seq_release,
216 static int __init ei_debugfs_init(void)
218 struct dentry *dir, *file;
220 dir = debugfs_create_dir("error_injection", NULL);
224 file = debugfs_create_file("list", 0444, dir, NULL, &debugfs_ei_ops);
233 static int __init init_error_injection(void)
235 populate_kernel_ei_list();
237 if (!module_ei_init())
242 late_initcall(init_error_injection);