372 lines
8.6 KiB
C
372 lines
8.6 KiB
C
/*
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* security/tomoyo/gc.c
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*
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* Implementation of the Domain-Based Mandatory Access Control.
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*
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* Copyright (C) 2005-2010 NTT DATA CORPORATION
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*
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*/
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#include "common.h"
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#include <linux/kthread.h>
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#include <linux/slab.h>
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enum tomoyo_gc_id {
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TOMOYO_ID_DOMAIN_INITIALIZER,
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TOMOYO_ID_DOMAIN_KEEPER,
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TOMOYO_ID_ALIAS,
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TOMOYO_ID_GLOBALLY_READABLE,
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TOMOYO_ID_PATTERN,
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TOMOYO_ID_NO_REWRITE,
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TOMOYO_ID_MANAGER,
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TOMOYO_ID_NAME,
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TOMOYO_ID_ACL,
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TOMOYO_ID_DOMAIN
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};
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struct tomoyo_gc_entry {
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struct list_head list;
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int type;
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void *element;
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};
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static LIST_HEAD(tomoyo_gc_queue);
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static DEFINE_MUTEX(tomoyo_gc_mutex);
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/* Caller holds tomoyo_policy_lock mutex. */
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static bool tomoyo_add_to_gc(const int type, void *element)
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{
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struct tomoyo_gc_entry *entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
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if (!entry)
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return false;
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entry->type = type;
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entry->element = element;
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list_add(&entry->list, &tomoyo_gc_queue);
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return true;
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}
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static void tomoyo_del_allow_read
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(struct tomoyo_globally_readable_file_entry *ptr)
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{
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tomoyo_put_name(ptr->filename);
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}
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static void tomoyo_del_file_pattern(struct tomoyo_pattern_entry *ptr)
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{
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tomoyo_put_name(ptr->pattern);
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}
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static void tomoyo_del_no_rewrite(struct tomoyo_no_rewrite_entry *ptr)
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{
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tomoyo_put_name(ptr->pattern);
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}
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static void tomoyo_del_domain_initializer
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(struct tomoyo_domain_initializer_entry *ptr)
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{
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tomoyo_put_name(ptr->domainname);
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tomoyo_put_name(ptr->program);
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}
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static void tomoyo_del_domain_keeper(struct tomoyo_domain_keeper_entry *ptr)
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{
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tomoyo_put_name(ptr->domainname);
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tomoyo_put_name(ptr->program);
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}
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static void tomoyo_del_alias(struct tomoyo_alias_entry *ptr)
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{
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tomoyo_put_name(ptr->original_name);
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tomoyo_put_name(ptr->aliased_name);
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}
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static void tomoyo_del_manager(struct tomoyo_policy_manager_entry *ptr)
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{
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tomoyo_put_name(ptr->manager);
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}
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static void tomoyo_del_acl(struct tomoyo_acl_info *acl)
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{
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switch (acl->type) {
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case TOMOYO_TYPE_PATH_ACL:
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{
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struct tomoyo_path_acl *entry
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= container_of(acl, typeof(*entry), head);
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tomoyo_put_name(entry->filename);
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}
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break;
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case TOMOYO_TYPE_PATH2_ACL:
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{
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struct tomoyo_path2_acl *entry
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= container_of(acl, typeof(*entry), head);
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tomoyo_put_name(entry->filename1);
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tomoyo_put_name(entry->filename2);
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}
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break;
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default:
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printk(KERN_WARNING "Unknown type\n");
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break;
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}
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}
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static bool tomoyo_del_domain(struct tomoyo_domain_info *domain)
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{
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struct tomoyo_acl_info *acl;
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struct tomoyo_acl_info *tmp;
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/*
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* Since we don't protect whole execve() operation using SRCU,
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* we need to recheck domain->users at this point.
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*
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* (1) Reader starts SRCU section upon execve().
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* (2) Reader traverses tomoyo_domain_list and finds this domain.
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* (3) Writer marks this domain as deleted.
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* (4) Garbage collector removes this domain from tomoyo_domain_list
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* because this domain is marked as deleted and used by nobody.
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* (5) Reader saves reference to this domain into
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* "struct linux_binprm"->cred->security .
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* (6) Reader finishes SRCU section, although execve() operation has
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* not finished yet.
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* (7) Garbage collector waits for SRCU synchronization.
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* (8) Garbage collector kfree() this domain because this domain is
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* used by nobody.
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* (9) Reader finishes execve() operation and restores this domain from
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* "struct linux_binprm"->cred->security.
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*
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* By updating domain->users at (5), we can solve this race problem
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* by rechecking domain->users at (8).
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*/
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if (atomic_read(&domain->users))
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return false;
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list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
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tomoyo_del_acl(acl);
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tomoyo_memory_free(acl);
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}
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tomoyo_put_name(domain->domainname);
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return true;
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}
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static void tomoyo_del_name(const struct tomoyo_name_entry *ptr)
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{
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}
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static void tomoyo_collect_entry(void)
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{
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mutex_lock(&tomoyo_policy_lock);
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{
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struct tomoyo_globally_readable_file_entry *ptr;
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list_for_each_entry_rcu(ptr, &tomoyo_globally_readable_list,
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list) {
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if (!ptr->is_deleted)
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continue;
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if (tomoyo_add_to_gc(TOMOYO_ID_GLOBALLY_READABLE, ptr))
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list_del_rcu(&ptr->list);
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else
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break;
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}
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}
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{
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struct tomoyo_pattern_entry *ptr;
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list_for_each_entry_rcu(ptr, &tomoyo_pattern_list, list) {
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if (!ptr->is_deleted)
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continue;
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if (tomoyo_add_to_gc(TOMOYO_ID_PATTERN, ptr))
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list_del_rcu(&ptr->list);
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else
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break;
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}
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}
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{
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struct tomoyo_no_rewrite_entry *ptr;
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list_for_each_entry_rcu(ptr, &tomoyo_no_rewrite_list, list) {
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if (!ptr->is_deleted)
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continue;
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if (tomoyo_add_to_gc(TOMOYO_ID_NO_REWRITE, ptr))
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list_del_rcu(&ptr->list);
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else
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break;
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}
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}
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{
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struct tomoyo_domain_initializer_entry *ptr;
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list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list,
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list) {
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if (!ptr->is_deleted)
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continue;
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if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_INITIALIZER, ptr))
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list_del_rcu(&ptr->list);
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else
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break;
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}
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}
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{
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struct tomoyo_domain_keeper_entry *ptr;
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list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
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if (!ptr->is_deleted)
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continue;
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if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_KEEPER, ptr))
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list_del_rcu(&ptr->list);
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else
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break;
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}
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}
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{
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struct tomoyo_alias_entry *ptr;
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list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
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if (!ptr->is_deleted)
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continue;
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if (tomoyo_add_to_gc(TOMOYO_ID_ALIAS, ptr))
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list_del_rcu(&ptr->list);
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else
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break;
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}
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}
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{
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struct tomoyo_policy_manager_entry *ptr;
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list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list,
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list) {
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if (!ptr->is_deleted)
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continue;
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if (tomoyo_add_to_gc(TOMOYO_ID_MANAGER, ptr))
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list_del_rcu(&ptr->list);
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else
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break;
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}
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}
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{
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struct tomoyo_domain_info *domain;
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list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
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struct tomoyo_acl_info *acl;
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list_for_each_entry_rcu(acl, &domain->acl_info_list,
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list) {
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switch (acl->type) {
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case TOMOYO_TYPE_PATH_ACL:
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if (container_of(acl,
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struct tomoyo_path_acl,
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head)->perm ||
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container_of(acl,
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struct tomoyo_path_acl,
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head)->perm_high)
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continue;
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break;
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case TOMOYO_TYPE_PATH2_ACL:
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if (container_of(acl,
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struct tomoyo_path2_acl,
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head)->perm)
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continue;
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break;
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default:
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continue;
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}
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if (tomoyo_add_to_gc(TOMOYO_ID_ACL, acl))
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list_del_rcu(&acl->list);
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else
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break;
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}
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if (!domain->is_deleted || atomic_read(&domain->users))
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continue;
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/*
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* Nobody is referring this domain. But somebody may
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* refer this domain after successful execve().
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* We recheck domain->users after SRCU synchronization.
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*/
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if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN, domain))
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list_del_rcu(&domain->list);
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else
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break;
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}
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}
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mutex_unlock(&tomoyo_policy_lock);
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mutex_lock(&tomoyo_name_list_lock);
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{
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int i;
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for (i = 0; i < TOMOYO_MAX_HASH; i++) {
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struct tomoyo_name_entry *ptr;
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list_for_each_entry_rcu(ptr, &tomoyo_name_list[i],
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list) {
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if (atomic_read(&ptr->users))
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continue;
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if (tomoyo_add_to_gc(TOMOYO_ID_NAME, ptr))
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list_del_rcu(&ptr->list);
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else {
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i = TOMOYO_MAX_HASH;
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break;
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}
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}
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}
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}
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mutex_unlock(&tomoyo_name_list_lock);
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}
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static void tomoyo_kfree_entry(void)
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{
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struct tomoyo_gc_entry *p;
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struct tomoyo_gc_entry *tmp;
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list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) {
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switch (p->type) {
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case TOMOYO_ID_DOMAIN_INITIALIZER:
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tomoyo_del_domain_initializer(p->element);
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break;
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case TOMOYO_ID_DOMAIN_KEEPER:
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tomoyo_del_domain_keeper(p->element);
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break;
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case TOMOYO_ID_ALIAS:
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tomoyo_del_alias(p->element);
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break;
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case TOMOYO_ID_GLOBALLY_READABLE:
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tomoyo_del_allow_read(p->element);
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break;
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case TOMOYO_ID_PATTERN:
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tomoyo_del_file_pattern(p->element);
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break;
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case TOMOYO_ID_NO_REWRITE:
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tomoyo_del_no_rewrite(p->element);
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break;
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case TOMOYO_ID_MANAGER:
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tomoyo_del_manager(p->element);
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break;
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case TOMOYO_ID_NAME:
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tomoyo_del_name(p->element);
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break;
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case TOMOYO_ID_ACL:
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tomoyo_del_acl(p->element);
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break;
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case TOMOYO_ID_DOMAIN:
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if (!tomoyo_del_domain(p->element))
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continue;
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break;
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default:
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printk(KERN_WARNING "Unknown type\n");
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break;
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}
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tomoyo_memory_free(p->element);
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list_del(&p->list);
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kfree(p);
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}
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}
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static int tomoyo_gc_thread(void *unused)
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{
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daemonize("GC for TOMOYO");
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if (mutex_trylock(&tomoyo_gc_mutex)) {
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int i;
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for (i = 0; i < 10; i++) {
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tomoyo_collect_entry();
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if (list_empty(&tomoyo_gc_queue))
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break;
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synchronize_srcu(&tomoyo_ss);
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tomoyo_kfree_entry();
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}
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mutex_unlock(&tomoyo_gc_mutex);
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}
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do_exit(0);
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}
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void tomoyo_run_gc(void)
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{
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struct task_struct *task = kthread_create(tomoyo_gc_thread, NULL,
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"GC for TOMOYO");
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if (!IS_ERR(task))
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wake_up_process(task);
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}
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