TOMOYO: Add garbage collector.
This patch adds garbage collector support to TOMOYO.
Elements are protected by "struct srcu_struct tomoyo_ss".
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/tomoyo/gc.c b/security/tomoyo/gc.c
new file mode 100644
index 0000000..ee15da3
--- /dev/null
+++ b/security/tomoyo/gc.c
@@ -0,0 +1,370 @@
+/*
+ * security/tomoyo/gc.c
+ *
+ * Implementation of the Domain-Based Mandatory Access Control.
+ *
+ * Copyright (C) 2005-2010 NTT DATA CORPORATION
+ *
+ */
+
+#include "common.h"
+#include <linux/kthread.h>
+
+enum tomoyo_gc_id {
+ TOMOYO_ID_DOMAIN_INITIALIZER,
+ TOMOYO_ID_DOMAIN_KEEPER,
+ TOMOYO_ID_ALIAS,
+ TOMOYO_ID_GLOBALLY_READABLE,
+ TOMOYO_ID_PATTERN,
+ TOMOYO_ID_NO_REWRITE,
+ TOMOYO_ID_MANAGER,
+ TOMOYO_ID_NAME,
+ TOMOYO_ID_ACL,
+ TOMOYO_ID_DOMAIN
+};
+
+struct tomoyo_gc_entry {
+ struct list_head list;
+ int type;
+ void *element;
+};
+static LIST_HEAD(tomoyo_gc_queue);
+static DEFINE_MUTEX(tomoyo_gc_mutex);
+
+/* Caller holds tomoyo_policy_lock mutex. */
+static bool tomoyo_add_to_gc(const int type, void *element)
+{
+ struct tomoyo_gc_entry *entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
+ if (!entry)
+ return false;
+ entry->type = type;
+ entry->element = element;
+ list_add(&entry->list, &tomoyo_gc_queue);
+ return true;
+}
+
+static void tomoyo_del_allow_read
+(struct tomoyo_globally_readable_file_entry *ptr)
+{
+ tomoyo_put_name(ptr->filename);
+}
+
+static void tomoyo_del_file_pattern(struct tomoyo_pattern_entry *ptr)
+{
+ tomoyo_put_name(ptr->pattern);
+}
+
+static void tomoyo_del_no_rewrite(struct tomoyo_no_rewrite_entry *ptr)
+{
+ tomoyo_put_name(ptr->pattern);
+}
+
+static void tomoyo_del_domain_initializer
+(struct tomoyo_domain_initializer_entry *ptr)
+{
+ tomoyo_put_name(ptr->domainname);
+ tomoyo_put_name(ptr->program);
+}
+
+static void tomoyo_del_domain_keeper(struct tomoyo_domain_keeper_entry *ptr)
+{
+ tomoyo_put_name(ptr->domainname);
+ tomoyo_put_name(ptr->program);
+}
+
+static void tomoyo_del_alias(struct tomoyo_alias_entry *ptr)
+{
+ tomoyo_put_name(ptr->original_name);
+ tomoyo_put_name(ptr->aliased_name);
+}
+
+static void tomoyo_del_manager(struct tomoyo_policy_manager_entry *ptr)
+{
+ tomoyo_put_name(ptr->manager);
+}
+
+static void tomoyo_del_acl(struct tomoyo_acl_info *acl)
+{
+ switch (acl->type) {
+ case TOMOYO_TYPE_SINGLE_PATH_ACL:
+ {
+ struct tomoyo_single_path_acl_record *entry
+ = container_of(acl, typeof(*entry), head);
+ tomoyo_put_name(entry->filename);
+ }
+ break;
+ case TOMOYO_TYPE_DOUBLE_PATH_ACL:
+ {
+ struct tomoyo_double_path_acl_record *entry
+ = container_of(acl, typeof(*entry), head);
+ tomoyo_put_name(entry->filename1);
+ tomoyo_put_name(entry->filename2);
+ }
+ break;
+ default:
+ printk(KERN_WARNING "Unknown type\n");
+ break;
+ }
+}
+
+static bool tomoyo_del_domain(struct tomoyo_domain_info *domain)
+{
+ struct tomoyo_acl_info *acl;
+ struct tomoyo_acl_info *tmp;
+ /*
+ * Since we don't protect whole execve() operation using SRCU,
+ * we need to recheck domain->users at this point.
+ *
+ * (1) Reader starts SRCU section upon execve().
+ * (2) Reader traverses tomoyo_domain_list and finds this domain.
+ * (3) Writer marks this domain as deleted.
+ * (4) Garbage collector removes this domain from tomoyo_domain_list
+ * because this domain is marked as deleted and used by nobody.
+ * (5) Reader saves reference to this domain into
+ * "struct linux_binprm"->cred->security .
+ * (6) Reader finishes SRCU section, although execve() operation has
+ * not finished yet.
+ * (7) Garbage collector waits for SRCU synchronization.
+ * (8) Garbage collector kfree() this domain because this domain is
+ * used by nobody.
+ * (9) Reader finishes execve() operation and restores this domain from
+ * "struct linux_binprm"->cred->security.
+ *
+ * By updating domain->users at (5), we can solve this race problem
+ * by rechecking domain->users at (8).
+ */
+ if (atomic_read(&domain->users))
+ return false;
+ list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
+ tomoyo_del_acl(acl);
+ tomoyo_memory_free(acl);
+ }
+ tomoyo_put_name(domain->domainname);
+ return true;
+}
+
+
+static void tomoyo_del_name(const struct tomoyo_name_entry *ptr)
+{
+}
+
+static void tomoyo_collect_entry(void)
+{
+ mutex_lock(&tomoyo_policy_lock);
+ {
+ struct tomoyo_globally_readable_file_entry *ptr;
+ list_for_each_entry_rcu(ptr, &tomoyo_globally_readable_list,
+ list) {
+ if (!ptr->is_deleted)
+ continue;
+ if (tomoyo_add_to_gc(TOMOYO_ID_GLOBALLY_READABLE, ptr))
+ list_del_rcu(&ptr->list);
+ else
+ break;
+ }
+ }
+ {
+ struct tomoyo_pattern_entry *ptr;
+ list_for_each_entry_rcu(ptr, &tomoyo_pattern_list, list) {
+ if (!ptr->is_deleted)
+ continue;
+ if (tomoyo_add_to_gc(TOMOYO_ID_PATTERN, ptr))
+ list_del_rcu(&ptr->list);
+ else
+ break;
+ }
+ }
+ {
+ struct tomoyo_no_rewrite_entry *ptr;
+ list_for_each_entry_rcu(ptr, &tomoyo_no_rewrite_list, list) {
+ if (!ptr->is_deleted)
+ continue;
+ if (tomoyo_add_to_gc(TOMOYO_ID_NO_REWRITE, ptr))
+ list_del_rcu(&ptr->list);
+ else
+ break;
+ }
+ }
+ {
+ struct tomoyo_domain_initializer_entry *ptr;
+ list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list,
+ list) {
+ if (!ptr->is_deleted)
+ continue;
+ if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_INITIALIZER, ptr))
+ list_del_rcu(&ptr->list);
+ else
+ break;
+ }
+ }
+ {
+ struct tomoyo_domain_keeper_entry *ptr;
+ list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
+ if (!ptr->is_deleted)
+ continue;
+ if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_KEEPER, ptr))
+ list_del_rcu(&ptr->list);
+ else
+ break;
+ }
+ }
+ {
+ struct tomoyo_alias_entry *ptr;
+ list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
+ if (!ptr->is_deleted)
+ continue;
+ if (tomoyo_add_to_gc(TOMOYO_ID_ALIAS, ptr))
+ list_del_rcu(&ptr->list);
+ else
+ break;
+ }
+ }
+ {
+ struct tomoyo_policy_manager_entry *ptr;
+ list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list,
+ list) {
+ if (!ptr->is_deleted)
+ continue;
+ if (tomoyo_add_to_gc(TOMOYO_ID_MANAGER, ptr))
+ list_del_rcu(&ptr->list);
+ else
+ break;
+ }
+ }
+ {
+ struct tomoyo_domain_info *domain;
+ list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
+ struct tomoyo_acl_info *acl;
+ list_for_each_entry_rcu(acl, &domain->acl_info_list,
+ list) {
+ switch (acl->type) {
+ case TOMOYO_TYPE_SINGLE_PATH_ACL:
+ if (container_of(acl,
+ struct tomoyo_single_path_acl_record,
+ head)->perm ||
+ container_of(acl,
+ struct tomoyo_single_path_acl_record,
+ head)->perm_high)
+ continue;
+ break;
+ case TOMOYO_TYPE_DOUBLE_PATH_ACL:
+ if (container_of(acl,
+ struct tomoyo_double_path_acl_record,
+ head)->perm)
+ continue;
+ break;
+ default:
+ continue;
+ }
+ if (tomoyo_add_to_gc(TOMOYO_ID_ACL, acl))
+ list_del_rcu(&acl->list);
+ else
+ break;
+ }
+ if (!domain->is_deleted || atomic_read(&domain->users))
+ continue;
+ /*
+ * Nobody is referring this domain. But somebody may
+ * refer this domain after successful execve().
+ * We recheck domain->users after SRCU synchronization.
+ */
+ if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN, domain))
+ list_del_rcu(&domain->list);
+ else
+ break;
+ }
+ }
+ mutex_unlock(&tomoyo_policy_lock);
+ mutex_lock(&tomoyo_name_list_lock);
+ {
+ int i;
+ for (i = 0; i < TOMOYO_MAX_HASH; i++) {
+ struct tomoyo_name_entry *ptr;
+ list_for_each_entry_rcu(ptr, &tomoyo_name_list[i],
+ list) {
+ if (atomic_read(&ptr->users))
+ continue;
+ if (tomoyo_add_to_gc(TOMOYO_ID_NAME, ptr))
+ list_del_rcu(&ptr->list);
+ else {
+ i = TOMOYO_MAX_HASH;
+ break;
+ }
+ }
+ }
+ }
+ mutex_unlock(&tomoyo_name_list_lock);
+}
+
+static void tomoyo_kfree_entry(void)
+{
+ struct tomoyo_gc_entry *p;
+ struct tomoyo_gc_entry *tmp;
+
+ list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) {
+ switch (p->type) {
+ case TOMOYO_ID_DOMAIN_INITIALIZER:
+ tomoyo_del_domain_initializer(p->element);
+ break;
+ case TOMOYO_ID_DOMAIN_KEEPER:
+ tomoyo_del_domain_keeper(p->element);
+ break;
+ case TOMOYO_ID_ALIAS:
+ tomoyo_del_alias(p->element);
+ break;
+ case TOMOYO_ID_GLOBALLY_READABLE:
+ tomoyo_del_allow_read(p->element);
+ break;
+ case TOMOYO_ID_PATTERN:
+ tomoyo_del_file_pattern(p->element);
+ break;
+ case TOMOYO_ID_NO_REWRITE:
+ tomoyo_del_no_rewrite(p->element);
+ break;
+ case TOMOYO_ID_MANAGER:
+ tomoyo_del_manager(p->element);
+ break;
+ case TOMOYO_ID_NAME:
+ tomoyo_del_name(p->element);
+ break;
+ case TOMOYO_ID_ACL:
+ tomoyo_del_acl(p->element);
+ break;
+ case TOMOYO_ID_DOMAIN:
+ if (!tomoyo_del_domain(p->element))
+ continue;
+ break;
+ default:
+ printk(KERN_WARNING "Unknown type\n");
+ break;
+ }
+ tomoyo_memory_free(p->element);
+ list_del(&p->list);
+ kfree(p);
+ }
+}
+
+static int tomoyo_gc_thread(void *unused)
+{
+ daemonize("GC for TOMOYO");
+ if (mutex_trylock(&tomoyo_gc_mutex)) {
+ int i;
+ for (i = 0; i < 10; i++) {
+ tomoyo_collect_entry();
+ if (list_empty(&tomoyo_gc_queue))
+ break;
+ synchronize_srcu(&tomoyo_ss);
+ tomoyo_kfree_entry();
+ }
+ mutex_unlock(&tomoyo_gc_mutex);
+ }
+ do_exit(0);
+}
+
+void tomoyo_run_gc(void)
+{
+ struct task_struct *task = kthread_create(tomoyo_gc_thread, NULL,
+ "GC for TOMOYO");
+ if (!IS_ERR(task))
+ wake_up_process(task);
+}