diff options
Diffstat (limited to 'security/tomoyo/gc.c')
| -rw-r--r-- | security/tomoyo/gc.c | 371 |
1 files changed, 371 insertions, 0 deletions
diff --git a/security/tomoyo/gc.c b/security/tomoyo/gc.c new file mode 100644 index 00000000000..d9ad35bc7fa --- /dev/null +++ b/security/tomoyo/gc.c @@ -0,0 +1,371 @@ +/* + * 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> +#include <linux/slab.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_PATH_ACL: + { + struct tomoyo_path_acl *entry + = container_of(acl, typeof(*entry), head); + tomoyo_put_name(entry->filename); + } + break; + case TOMOYO_TYPE_PATH2_ACL: + { + struct tomoyo_path2_acl *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_PATH_ACL: + if (container_of(acl, + struct tomoyo_path_acl, + head)->perm || + container_of(acl, + struct tomoyo_path_acl, + head)->perm_high) + continue; + break; + case TOMOYO_TYPE_PATH2_ACL: + if (container_of(acl, + struct tomoyo_path2_acl, + 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); +} |