// SPDX-License-Identifier: GPL-2.0// error-inject.c: Function-level error injection table#include <linux/error-injection.h>#include <linux/debugfs.h>#include <linux/kallsyms.h>#include <linux/kprobes.h>#include <linux/module.h>#include <linux/mutex.h>#include <linux/list.h>#include <linux/slab.h> /* Whitelist of symbols that can be overridden for error injection. */static LIST_HEAD(error_injection_list);static DEFINE_MUTEX(ei_mutex);struct ei_entry {	struct list_head list;	unsigned long start_addr;	unsigned long end_addr;	int etype;	void *priv;}; bool within_error_injection_list(unsigned long addr){	struct ei_entry *ent;	bool ret = false; 	mutex_lock(&ei_mutex);	list_for_each_entry(ent, &error_injection_list, list) {		if (addr >= ent->start_addr && addr < ent->end_addr) {			ret = true;			break;		}	}	mutex_unlock(&ei_mutex);	return ret;} int get_injectable_error_type(unsigned long addr){	struct ei_entry *ent; 	list_for_each_entry(ent, &error_injection_list, list) {		if (addr >= ent->start_addr && addr < ent->end_addr)			return ent->etype;	}	return EI_ETYPE_NONE;} /* * Lookup and populate the error_injection_list. * * For safety reasons we only allow certain functions to be overridden with * bpf_error_injection, so we need to populate the list of the symbols that have * been marked as safe for overriding. */static void populate_error_injection_list(struct error_injection_entry *start,					  struct error_injection_entry *end,					  void *priv){	struct error_injection_entry *iter;	struct ei_entry *ent;	unsigned long entry, offset = 0, size = 0; 	mutex_lock(&ei_mutex);	for (iter = start; iter < end; iter++) {		entry = arch_deref_entry_point((void *)iter->addr); 		if (!kernel_text_address(entry) ||		    !kallsyms_lookup_size_offset(entry, &size, &offset)) {			pr_err("Failed to find error inject entry at %p\n",				(void *)entry);			continue;		} 		ent = kmalloc(sizeof(*ent), GFP_KERNEL);		if (!ent)			break;		ent->start_addr = entry;		ent->end_addr = entry + size;		ent->etype = iter->etype;		ent->priv = priv;		INIT_LIST_HEAD(&ent->list);		list_add_tail(&ent->list, &error_injection_list);	}	mutex_unlock(&ei_mutex);} /* Markers of the _error_inject_whitelist section */extern struct error_injection_entry __start_error_injection_whitelist[];extern struct error_injection_entry __stop_error_injection_whitelist[]; static void __init populate_kernel_ei_list(void){	populate_error_injection_list(__start_error_injection_whitelist,				      __stop_error_injection_whitelist,				      NULL);} #ifdef CONFIG_MODULESstatic void module_load_ei_list(struct module *mod){	if (!mod->num_ei_funcs)		return; 	populate_error_injection_list(mod->ei_funcs,				      mod->ei_funcs + mod->num_ei_funcs, mod);} static void module_unload_ei_list(struct module *mod){	struct ei_entry *ent, *n; 	if (!mod->num_ei_funcs)		return; 	mutex_lock(&ei_mutex);	list_for_each_entry_safe(ent, n, &error_injection_list, list) {		if (ent->priv == mod) {			list_del_init(&ent->list);			kfree(ent);		}	}	mutex_unlock(&ei_mutex);} /* Module notifier call back, checking error injection table on the module */static int ei_module_callback(struct notifier_block *nb,			      unsigned long val, void *data){	struct module *mod = data; 	if (val == MODULE_STATE_COMING)		module_load_ei_list(mod);	else if (val == MODULE_STATE_GOING)		module_unload_ei_list(mod); 	return NOTIFY_DONE;} static struct notifier_block ei_module_nb = {	.notifier_call = ei_module_callback,	.priority = 0}; static __init int module_ei_init(void){	return register_module_notifier(&ei_module_nb);}#else /* !CONFIG_MODULES */#define module_ei_init()	(0)#endif /* * error_injection/whitelist -- shows which functions can be overridden for * error injection. */static void *ei_seq_start(struct seq_file *m, loff_t *pos){	mutex_lock(&ei_mutex);	return seq_list_start(&error_injection_list, *pos);} static void ei_seq_stop(struct seq_file *m, void *v){	mutex_unlock(&ei_mutex);} static void *ei_seq_next(struct seq_file *m, void *v, loff_t *pos){	return seq_list_next(v, &error_injection_list, pos);} static const char *error_type_string(int etype){	switch (etype) {	case EI_ETYPE_NULL:		return "NULL";	case EI_ETYPE_ERRNO:		return "ERRNO";	case EI_ETYPE_ERRNO_NULL:		return "ERRNO_NULL";	case EI_ETYPE_TRUE:		return "TRUE";	default:		return "(unknown)";	}} static int ei_seq_show(struct seq_file *m, void *v){	struct ei_entry *ent = list_entry(v, struct ei_entry, list); 	seq_printf(m, "%ps\t%s\n", (void *)ent->start_addr,		   error_type_string(ent->etype));	return 0;} static const struct seq_operations ei_seq_ops = {	.start = ei_seq_start,	.next  = ei_seq_next,	.stop  = ei_seq_stop,	.show  = ei_seq_show,}; static int ei_open(struct inode *inode, struct file *filp){	return seq_open(filp, &ei_seq_ops);} static const struct file_operations debugfs_ei_ops = {	.open           = ei_open,	.read           = seq_read,	.llseek         = seq_lseek,	.release        = seq_release,}; static int __init ei_debugfs_init(void){	struct dentry *dir, *file; 	dir = debugfs_create_dir("error_injection", NULL);	if (!dir)		return -ENOMEM; 	file = debugfs_create_file("list", 0444, dir, NULL, &debugfs_ei_ops);	if (!file) {		debugfs_remove(dir);		return -ENOMEM;	} 	return 0;} static int __init init_error_injection(void){	populate_kernel_ei_list(); 	if (!module_ei_init())		ei_debugfs_init(); 	return 0;}late_initcall(init_error_injection);