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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Linux Kernel Dump Test Module for testing kernel crashes conditions:
* induces system failures at predefined crashpoints and under predefined
* operational conditions in order to evaluate the reliability of kernel
* sanity checking and crash dumps obtained using different dumping
* solutions.
*
* Copyright (C) IBM Corporation, 2006
*
* Author: Ankita Garg <ankita@in.ibm.com>
*
* It is adapted from the Linux Kernel Dump Test Tool by
* Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net>
*
* Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net>
*
* See Documentation/fault-injection/provoke-crashes.rst for instructions
*/
#include "lkdtm.h"
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/buffer_head.h>
#include <linux/kprobes.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/debugfs.h>
#include <linux/utsname.h>
#define DEFAULT_COUNT 10
static int lkdtm_debugfs_open(struct inode *inode, struct file *file);
static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
size_t count, loff_t *off);
static ssize_t direct_entry(struct file *f, const char __user *user_buf,
size_t count, loff_t *off);
#ifdef CONFIG_KPROBES
static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs);
static ssize_t lkdtm_debugfs_entry(struct file *f,
const char __user *user_buf,
size_t count, loff_t *off);
# define CRASHPOINT_KPROBE(_symbol) \
.kprobe = { \
.symbol_name = (_symbol), \
.pre_handler = lkdtm_kprobe_handler, \
},
# define CRASHPOINT_WRITE(_symbol) \
(_symbol) ? lkdtm_debugfs_entry : direct_entry
#else
# define CRASHPOINT_KPROBE(_symbol)
# define CRASHPOINT_WRITE(_symbol) direct_entry
#endif
/* Crash points */
struct crashpoint {
const char *name;
const struct file_operations fops;
struct kprobe kprobe;
};
#define CRASHPOINT(_name, _symbol) \
{ \
.name = _name, \
.fops = { \
.read = lkdtm_debugfs_read, \
.llseek = generic_file_llseek, \
.open = lkdtm_debugfs_open, \
.write = CRASHPOINT_WRITE(_symbol) \
}, \
CRASHPOINT_KPROBE(_symbol) \
}
/* Define the possible places where we can trigger a crash point. */
static struct crashpoint crashpoints[] = {
CRASHPOINT("DIRECT", NULL),
#ifdef CONFIG_KPROBES
CRASHPOINT("INT_HARDWARE_ENTRY", "do_IRQ"),
CRASHPOINT("INT_HW_IRQ_EN", "handle_irq_event"),
CRASHPOINT("INT_TASKLET_ENTRY", "tasklet_action"),
CRASHPOINT("FS_DEVRW", "ll_rw_block"),
CRASHPOINT("MEM_SWAPOUT", "shrink_inactive_list"),
CRASHPOINT("TIMERADD", "hrtimer_start"),
CRASHPOINT("SCSI_QUEUE_RQ", "scsi_queue_rq"),
#endif
};
/* List of possible types for crashes that can be triggered. */
static const struct crashtype_category *crashtype_categories[] = {
&bugs_crashtypes,
&heap_crashtypes,
&perms_crashtypes,
&refcount_crashtypes,
&usercopy_crashtypes,
&stackleak_crashtypes,
&cfi_crashtypes,
&fortify_crashtypes,
#ifdef CONFIG_PPC_64S_HASH_MMU
&powerpc_crashtypes,
#endif
};
/* Global kprobe entry and crashtype. */
static struct kprobe *lkdtm_kprobe;
static struct crashpoint *lkdtm_crashpoint;
static const struct crashtype *lkdtm_crashtype;
/* Module parameters */
static int recur_count = -1;
module_param(recur_count, int, 0644);
MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
static char* cpoint_name;
module_param(cpoint_name, charp, 0444);
MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
static char* cpoint_type;
module_param(cpoint_type, charp, 0444);
MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
"hitting the crash point");
static int cpoint_count = DEFAULT_COUNT;
module_param(cpoint_count, int, 0644);
MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
"crash point is to be hit to trigger action");
/*
* For test debug reporting when CI systems provide terse summaries.
* TODO: Remove this once reasonable reporting exists in most CI systems:
* https://lore.kernel.org/lkml/CAHk-=wiFvfkoFixTapvvyPMN9pq5G-+Dys2eSyBa1vzDGAO5+A@mail.gmail.com
*/
char *lkdtm_kernel_info;
/* Return the crashtype number or NULL if the name is invalid */
static const struct crashtype *find_crashtype(const char *name)
{
int cat, idx;
for (cat = 0; cat < ARRAY_SIZE(crashtype_categories); cat++) {
for (idx = 0; idx < crashtype_categories[cat]->len; idx++) {
struct crashtype *crashtype;
crashtype = &crashtype_categories[cat]->crashtypes[idx];
if (!strcmp(name, crashtype->name))
return crashtype;
}
}
return NULL;
}
/*
* This is forced noinline just so it distinctly shows up in the stackdump
* which makes validation of expected lkdtm crashes easier.
*/
static noinline void lkdtm_do_action(const struct crashtype *crashtype)
{
if (WARN_ON(!crashtype || !crashtype->func))
return;
crashtype->func();
}
static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
const struct crashtype *crashtype)
{
int ret;
/* If this doesn't have a symbol, just call immediately. */
if (!crashpoint->kprobe.symbol_name) {
lkdtm_do_action(crashtype);
return 0;
}
if (lkdtm_kprobe != NULL)
unregister_kprobe(lkdtm_kprobe);
lkdtm_crashpoint = crashpoint;
lkdtm_crashtype = crashtype;
lkdtm_kprobe = &crashpoint->kprobe;
ret = register_kprobe(lkdtm_kprobe);
if (ret < 0) {
pr_info("Couldn't register kprobe %s\n",
crashpoint->kprobe.symbol_name);
lkdtm_kprobe = NULL;
lkdtm_crashpoint = NULL;
lkdtm_crashtype = NULL;
}
return ret;
}
#ifdef CONFIG_KPROBES
/* Global crash counter and spinlock. */
static int crash_count = DEFAULT_COUNT;
static DEFINE_SPINLOCK(crash_count_lock);
/* Called by kprobe entry points. */
static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
{
unsigned long flags;
bool do_it = false;
if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
return 0;
spin_lock_irqsave(&crash_count_lock, flags);
crash_count--;
pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
if (crash_count == 0) {
do_it = true;
crash_count = cpoint_count;
}
spin_unlock_irqrestore(&crash_count_lock, flags);
if (do_it)
lkdtm_do_action(lkdtm_crashtype);
return 0;
}
static ssize_t lkdtm_debugfs_entry(struct file *f,
const char __user *user_buf,
size_t count, loff_t *off)
{
struct crashpoint *crashpoint = file_inode(f)->i_private;
const struct crashtype *crashtype = NULL;
char *buf;
int err;
if (count >= PAGE_SIZE)
return -EINVAL;
buf = (char *)__get_free_page(GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (copy_from_user(buf, user_buf, count)) {
free_page((unsigned long) buf);
return -EFAULT;
}
/* NULL-terminate and remove enter */
buf[count] = '\0';
strim(buf);
crashtype = find_crashtype(buf);
free_page((unsigned long)buf);
if (!crashtype)
return -EINVAL;
err = lkdtm_register_cpoint(crashpoint, crashtype);
if (err < 0)
return err;
*off += count;
return count;
}
#endif
/* Generic read callback that just prints out the available crash types */
static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
size_t count, loff_t *off)
{
int n, cat, idx;
ssize_t out;
char *buf;
buf = (char *)__get_free_page(GFP_KERNEL);
if (buf == NULL)
return -ENOMEM;
n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
for (cat = 0; cat < ARRAY_SIZE(crashtype_categories); cat++) {
for (idx = 0; idx < crashtype_categories[cat]->len; idx++) {
struct crashtype *crashtype;
crashtype = &crashtype_categories[cat]->crashtypes[idx];
n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
crashtype->name);
}
}
buf[n] = '\0';
out = simple_read_from_buffer(user_buf, count, off,
buf, n);
free_page((unsigned long) buf);
return out;
}
static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
{
return 0;
}
/* Special entry to just crash directly. Available without KPROBEs */
static ssize_t direct_entry(struct file *f, const char __user *user_buf,
size_t count, loff_t *off)
{
const struct crashtype *crashtype;
char *buf;
if (count >= PAGE_SIZE)
return -EINVAL;
if (count < 1)
return -EINVAL;
buf = (char *)__get_free_page(GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (copy_from_user(buf, user_buf, count)) {
free_page((unsigned long) buf);
return -EFAULT;
}
/* NULL-terminate and remove enter */
buf[count] = '\0';
strim(buf);
crashtype = find_crashtype(buf);
free_page((unsigned long) buf);
if (!crashtype)
return -EINVAL;
pr_info("Performing direct entry %s\n", crashtype->name);
lkdtm_do_action(crashtype);
*off += count;
return count;
}
#ifndef MODULE
/*
* To avoid needing to export parse_args(), just don't use this code
* when LKDTM is built as a module.
*/
struct check_cmdline_args {
const char *param;
int value;
};
static int lkdtm_parse_one(char *param, char *val,
const char *unused, void *arg)
{
struct check_cmdline_args *args = arg;
/* short circuit if we already found a value. */
if (args->value != -ESRCH)
return 0;
if (strncmp(param, args->param, strlen(args->param)) == 0) {
bool bool_result;
int ret;
ret = kstrtobool(val, &bool_result);
if (ret == 0)
args->value = bool_result;
}
return 0;
}
int lkdtm_check_bool_cmdline(const char *param)
{
char *command_line;
struct check_cmdline_args args = {
.param = param,
.value = -ESRCH,
};
command_line = kstrdup(saved_command_line, GFP_KERNEL);
if (!command_line)
return -ENOMEM;
parse_args("Setting sysctl args", command_line,
NULL, 0, -1, -1, &args, lkdtm_parse_one);
kfree(command_line);
return args.value;
}
#endif
static struct dentry *lkdtm_debugfs_root;
static int __init lkdtm_module_init(void)
{
struct crashpoint *crashpoint = NULL;
const struct crashtype *crashtype = NULL;
int ret;
int i;
/* Neither or both of these need to be set */
if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
pr_err("Need both cpoint_type and cpoint_name or neither\n");
return -EINVAL;
}
if (cpoint_type) {
crashtype = find_crashtype(cpoint_type);
if (!crashtype) {
pr_err("Unknown crashtype '%s'\n", cpoint_type);
return -EINVAL;
}
}
if (cpoint_name) {
for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
if (!strcmp(cpoint_name, crashpoints[i].name))
crashpoint = &crashpoints[i];
}
/* Refuse unknown crashpoints. */
if (!crashpoint) {
pr_err("Invalid crashpoint %s\n", cpoint_name);
return -EINVAL;
}
}
#ifdef CONFIG_KPROBES
/* Set crash count. */
crash_count = cpoint_count;
#endif
/* Common initialization. */
lkdtm_kernel_info = kasprintf(GFP_KERNEL, "kernel (%s %s)",
init_uts_ns.name.release,
init_uts_ns.name.machine);
/* Handle test-specific initialization. */
lkdtm_bugs_init(&recur_count);
lkdtm_perms_init();
lkdtm_usercopy_init();
lkdtm_heap_init();
/* Register debugfs interface */
lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
/* Install debugfs trigger files. */
for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
struct crashpoint *cur = &crashpoints[i];
debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
&cur->fops);
}
/* Install crashpoint if one was selected. */
if (crashpoint) {
ret = lkdtm_register_cpoint(crashpoint, crashtype);
if (ret < 0) {
pr_info("Invalid crashpoint %s\n", crashpoint->name);
goto out_err;
}
pr_info("Crash point %s of type %s registered\n",
crashpoint->name, cpoint_type);
} else {
pr_info("No crash points registered, enable through debugfs\n");
}
return 0;
out_err:
debugfs_remove_recursive(lkdtm_debugfs_root);
return ret;
}
static void __exit lkdtm_module_exit(void)
{
debugfs_remove_recursive(lkdtm_debugfs_root);
/* Handle test-specific clean-up. */
lkdtm_heap_exit();
lkdtm_usercopy_exit();
if (lkdtm_kprobe != NULL)
unregister_kprobe(lkdtm_kprobe);
kfree(lkdtm_kernel_info);
pr_info("Crash point unregistered\n");
}
module_init(lkdtm_module_init);
module_exit(lkdtm_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Kernel crash testing module");