#include <linux/error-injection.h>
#include <linux/debugfs.h>
#include <linux/fault-inject.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs);
static void fei_post_handler(struct kprobe *kp, struct pt_regs *regs,
unsigned long flags)
{
}
struct fei_attr {
struct list_head list;
struct kprobe kp;
unsigned long retval;
};
static DEFINE_MUTEX(fei_lock);
static LIST_HEAD(fei_attr_list);
static DECLARE_FAULT_ATTR(fei_fault_attr);
static struct dentry *fei_debugfs_dir;
static unsigned long adjust_error_retval(unsigned long addr, unsigned long retv)
{
switch (get_injectable_error_type(addr)) {
case EI_ETYPE_NULL:
return 0;
case EI_ETYPE_ERRNO:
if (retv < (unsigned long)-MAX_ERRNO)
return (unsigned long)-EINVAL;
break;
case EI_ETYPE_ERRNO_NULL:
if (retv != 0 && retv < (unsigned long)-MAX_ERRNO)
return (unsigned long)-EINVAL;
break;
case EI_ETYPE_TRUE:
return 1;
}
return retv;
}
static struct fei_attr *fei_attr_new(const char *sym, unsigned long addr)
{
struct fei_attr *attr;
attr = kzalloc_obj(*attr);
if (attr) {
attr->kp.symbol_name = kstrdup(sym, GFP_KERNEL);
if (!attr->kp.symbol_name) {
kfree(attr);
return NULL;
}
attr->kp.pre_handler = fei_kprobe_handler;
attr->kp.post_handler = fei_post_handler;
attr->retval = adjust_error_retval(addr, 0);
INIT_LIST_HEAD(&attr->list);
}
return attr;
}
static void fei_attr_free(struct fei_attr *attr)
{
if (attr) {
kfree(attr->kp.symbol_name);
kfree(attr);
}
}
static struct fei_attr *fei_attr_lookup(const char *sym)
{
struct fei_attr *attr;
list_for_each_entry(attr, &fei_attr_list, list) {
if (!strcmp(attr->kp.symbol_name, sym))
return attr;
}
return NULL;
}
static bool fei_attr_is_valid(struct fei_attr *_attr)
{
struct fei_attr *attr;
list_for_each_entry(attr, &fei_attr_list, list) {
if (attr == _attr)
return true;
}
return false;
}
static int fei_retval_set(void *data, u64 val)
{
struct fei_attr *attr = data;
unsigned long retv = (unsigned long)val;
int err = 0;
mutex_lock(&fei_lock);
if (!fei_attr_is_valid(attr)) {
err = -ENOENT;
goto out;
}
if (attr->kp.addr) {
if (adjust_error_retval((unsigned long)attr->kp.addr,
val) != retv)
err = -EINVAL;
}
if (!err)
attr->retval = val;
out:
mutex_unlock(&fei_lock);
return err;
}
static int fei_retval_get(void *data, u64 *val)
{
struct fei_attr *attr = data;
int err = 0;
mutex_lock(&fei_lock);
if (!fei_attr_is_valid(attr))
err = -ENOENT;
else
*val = attr->retval;
mutex_unlock(&fei_lock);
return err;
}
DEFINE_DEBUGFS_ATTRIBUTE(fei_retval_ops, fei_retval_get, fei_retval_set,
"%llx\n");
static void fei_debugfs_add_attr(struct fei_attr *attr)
{
struct dentry *dir;
dir = debugfs_create_dir(attr->kp.symbol_name, fei_debugfs_dir);
debugfs_create_file("retval", 0600, dir, attr, &fei_retval_ops);
}
static void fei_debugfs_remove_attr(struct fei_attr *attr)
{
debugfs_lookup_and_remove(attr->kp.symbol_name, fei_debugfs_dir);
}
static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
{
struct fei_attr *attr = container_of(kp, struct fei_attr, kp);
if (should_fail(&fei_fault_attr, 1)) {
regs_set_return_value(regs, attr->retval);
override_function_with_return(regs);
return 1;
}
return 0;
}
NOKPROBE_SYMBOL(fei_kprobe_handler)
static void *fei_seq_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&fei_lock);
return seq_list_start(&fei_attr_list, *pos);
}
static void fei_seq_stop(struct seq_file *m, void *v)
{
mutex_unlock(&fei_lock);
}
static void *fei_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &fei_attr_list, pos);
}
static int fei_seq_show(struct seq_file *m, void *v)
{
struct fei_attr *attr = list_entry(v, struct fei_attr, list);
seq_printf(m, "%ps\n", attr->kp.addr);
return 0;
}
static const struct seq_operations fei_seq_ops = {
.start = fei_seq_start,
.next = fei_seq_next,
.stop = fei_seq_stop,
.show = fei_seq_show,
};
static int fei_open(struct inode *inode, struct file *file)
{
return seq_open(file, &fei_seq_ops);
}
static void fei_attr_remove(struct fei_attr *attr)
{
fei_debugfs_remove_attr(attr);
unregister_kprobe(&attr->kp);
list_del(&attr->list);
fei_attr_free(attr);
}
static void fei_attr_remove_all(void)
{
struct fei_attr *attr, *n;
list_for_each_entry_safe(attr, n, &fei_attr_list, list) {
fei_attr_remove(attr);
}
}
static ssize_t fei_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
struct fei_attr *attr;
unsigned long addr;
char *buf, *sym;
int ret;
if (count > KSYM_NAME_LEN)
count = KSYM_NAME_LEN;
buf = memdup_user_nul(buffer, count);
if (IS_ERR(buf))
return PTR_ERR(buf);
sym = strstrip(buf);
mutex_lock(&fei_lock);
if (sym[0] == '\0') {
fei_attr_remove_all();
ret = count;
goto out;
}
if (sym[0] == '!') {
attr = fei_attr_lookup(sym + 1);
if (!attr) {
ret = -ENOENT;
goto out;
}
fei_attr_remove(attr);
ret = count;
goto out;
}
addr = kallsyms_lookup_name(sym);
if (!addr) {
ret = -EINVAL;
goto out;
}
if (!within_error_injection_list(addr)) {
ret = -ERANGE;
goto out;
}
if (fei_attr_lookup(sym)) {
ret = -EBUSY;
goto out;
}
attr = fei_attr_new(sym, addr);
if (!attr) {
ret = -ENOMEM;
goto out;
}
ret = register_kprobe(&attr->kp);
if (ret) {
fei_attr_free(attr);
goto out;
}
fei_debugfs_add_attr(attr);
list_add_tail(&attr->list, &fei_attr_list);
ret = count;
out:
mutex_unlock(&fei_lock);
kfree(buf);
return ret;
}
static const struct file_operations fei_ops = {
.open = fei_open,
.read = seq_read,
.write = fei_write,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init fei_debugfs_init(void)
{
struct dentry *dir;
dir = fault_create_debugfs_attr("fail_function", NULL,
&fei_fault_attr);
if (IS_ERR(dir))
return PTR_ERR(dir);
debugfs_create_symlink("injectable", dir, "../error_injection/list");
debugfs_create_file("inject", 0600, dir, NULL, &fei_ops);
fei_debugfs_dir = dir;
return 0;
}
late_initcall(fei_debugfs_init);
