diff options
| -rw-r--r-- | security/tomoyo/common.c | 41 | ||||
| -rw-r--r-- | security/tomoyo/common.h | 8 | ||||
| -rw-r--r-- | security/tomoyo/gc.c | 278 |
3 files changed, 276 insertions, 51 deletions
diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c index 50481d2..691c340 100644 --- a/security/tomoyo/common.c +++ b/security/tomoyo/common.c @@ -1820,9 +1820,7 @@ static void tomoyo_read_self_domain(struct tomoyo_io_buffer *head) * @type: Type of interface. * @file: Pointer to "struct file". * - * Associates policy handler and returns 0 on success, -ENOMEM otherwise. - * - * Caller acquires tomoyo_read_lock(). + * Returns 0 on success, negative value otherwise. */ int tomoyo_open_control(const u8 type, struct file *file) { @@ -1921,9 +1919,6 @@ int tomoyo_open_control(const u8 type, struct file *file) return -ENOMEM; } } - if (type != TOMOYO_QUERY && type != TOMOYO_AUDIT) - head->reader_idx = tomoyo_read_lock(); - file->private_data = head; /* * If the file is /sys/kernel/security/tomoyo/query , increment the * observer counter. @@ -1932,6 +1927,8 @@ int tomoyo_open_control(const u8 type, struct file *file) */ if (type == TOMOYO_QUERY) atomic_inc(&tomoyo_query_observers); + file->private_data = head; + tomoyo_notify_gc(head, true); return 0; } @@ -2000,13 +1997,12 @@ static inline bool tomoyo_has_more_namespace(struct tomoyo_io_buffer *head) * @buffer_len: Size of @buffer. * * Returns bytes read on success, negative value otherwise. - * - * Caller holds tomoyo_read_lock(). */ int tomoyo_read_control(struct tomoyo_io_buffer *head, char __user *buffer, const int buffer_len) { int len; + int idx; if (!head->read) return -ENOSYS; @@ -2014,6 +2010,7 @@ int tomoyo_read_control(struct tomoyo_io_buffer *head, char __user *buffer, return -EINTR; head->read_user_buf = buffer; head->read_user_buf_avail = buffer_len; + idx = tomoyo_read_lock(); if (tomoyo_flush(head)) /* Call the policy handler. */ do { @@ -2021,6 +2018,7 @@ int tomoyo_read_control(struct tomoyo_io_buffer *head, char __user *buffer, head->read(head); } while (tomoyo_flush(head) && tomoyo_has_more_namespace(head)); + tomoyo_read_unlock(idx); len = head->read_user_buf - buffer; mutex_unlock(&head->io_sem); return len; @@ -2071,8 +2069,6 @@ static int tomoyo_parse_policy(struct tomoyo_io_buffer *head, char *line) * @buffer_len: Size of @buffer. * * Returns @buffer_len on success, negative value otherwise. - * - * Caller holds tomoyo_read_lock(). */ int tomoyo_write_control(struct tomoyo_io_buffer *head, const char __user *buffer, const int buffer_len) @@ -2080,12 +2076,14 @@ int tomoyo_write_control(struct tomoyo_io_buffer *head, int error = buffer_len; size_t avail_len = buffer_len; char *cp0 = head->write_buf; + int idx; if (!head->write) return -ENOSYS; if (!access_ok(VERIFY_READ, buffer, buffer_len)) return -EFAULT; if (mutex_lock_interruptible(&head->io_sem)) return -EINTR; + idx = tomoyo_read_lock(); /* Read a line and dispatch it to the policy handler. */ while (avail_len > 0) { char c; @@ -2148,6 +2146,7 @@ int tomoyo_write_control(struct tomoyo_io_buffer *head, } } out: + tomoyo_read_unlock(idx); mutex_unlock(&head->io_sem); return error; } @@ -2157,30 +2156,18 @@ out: * * @head: Pointer to "struct tomoyo_io_buffer". * - * Releases memory and returns 0. - * - * Caller looses tomoyo_read_lock(). + * Returns 0. */ int tomoyo_close_control(struct tomoyo_io_buffer *head) { - const bool is_write = !!head->write_buf; - /* * If the file is /sys/kernel/security/tomoyo/query , decrement the * observer counter. */ - if (head->type == TOMOYO_QUERY) - atomic_dec(&tomoyo_query_observers); - else if (head->type != TOMOYO_AUDIT) - tomoyo_read_unlock(head->reader_idx); - /* Release memory used for policy I/O. */ - kfree(head->read_buf); - head->read_buf = NULL; - kfree(head->write_buf); - head->write_buf = NULL; - kfree(head); - if (is_write) - tomoyo_run_gc(); + if (head->type == TOMOYO_QUERY && + atomic_dec_and_test(&tomoyo_query_observers)) + wake_up_all(&tomoyo_answer_wait); + tomoyo_notify_gc(head, false); return 0; } diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h index 53c8798..a5eeabc 100644 --- a/security/tomoyo/common.h +++ b/security/tomoyo/common.h @@ -441,8 +441,6 @@ struct tomoyo_io_buffer { int (*poll) (struct file *file, poll_table *wait); /* Exclusive lock for this structure. */ struct mutex io_sem; - /* Index returned by tomoyo_read_lock(). */ - int reader_idx; char __user *read_user_buf; int read_user_buf_avail; struct { @@ -480,6 +478,10 @@ struct tomoyo_io_buffer { int writebuf_size; /* Type of this interface. */ u8 type; + /* Users counter protected by tomoyo_io_buffer_list_lock. */ + u8 users; + /* List for telling GC not to kfree() elements. */ + struct list_head list; }; /* @@ -651,7 +653,7 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm); void tomoyo_print_ulong(char *buffer, const int buffer_len, const unsigned long value, const u8 type); void tomoyo_put_name_union(struct tomoyo_name_union *ptr); -void tomoyo_run_gc(void); +void tomoyo_notify_gc(struct tomoyo_io_buffer *head, const bool is_register); void tomoyo_memory_free(void *ptr); int tomoyo_update_domain(struct tomoyo_acl_info *new_entry, const int size, struct tomoyo_acl_param *param, diff --git a/security/tomoyo/gc.c b/security/tomoyo/gc.c index 782e844..1e1a6c8 100644 --- a/security/tomoyo/gc.c +++ b/security/tomoyo/gc.c @@ -11,13 +11,123 @@ #include <linux/kthread.h> #include <linux/slab.h> +/* The list for "struct tomoyo_io_buffer". */ +static LIST_HEAD(tomoyo_io_buffer_list); +/* Lock for protecting tomoyo_io_buffer_list. */ +static DEFINE_SPINLOCK(tomoyo_io_buffer_list_lock); + +/* Size of an element. */ +static const u8 tomoyo_element_size[TOMOYO_MAX_POLICY] = { + [TOMOYO_ID_GROUP] = sizeof(struct tomoyo_group), + [TOMOYO_ID_PATH_GROUP] = sizeof(struct tomoyo_path_group), + [TOMOYO_ID_NUMBER_GROUP] = sizeof(struct tomoyo_number_group), + [TOMOYO_ID_AGGREGATOR] = sizeof(struct tomoyo_aggregator), + [TOMOYO_ID_TRANSITION_CONTROL] = + sizeof(struct tomoyo_transition_control), + [TOMOYO_ID_MANAGER] = sizeof(struct tomoyo_manager), + /* [TOMOYO_ID_NAME] = "struct tomoyo_name"->size, */ + /* [TOMOYO_ID_ACL] = + tomoyo_acl_size["struct tomoyo_acl_info"->type], */ + [TOMOYO_ID_DOMAIN] = sizeof(struct tomoyo_domain_info), +}; + +/* Size of a domain ACL element. */ +static const u8 tomoyo_acl_size[] = { + [TOMOYO_TYPE_PATH_ACL] = sizeof(struct tomoyo_path_acl), + [TOMOYO_TYPE_PATH2_ACL] = sizeof(struct tomoyo_path2_acl), + [TOMOYO_TYPE_PATH_NUMBER_ACL] = sizeof(struct tomoyo_path_number_acl), + [TOMOYO_TYPE_MKDEV_ACL] = sizeof(struct tomoyo_mkdev_acl), + [TOMOYO_TYPE_MOUNT_ACL] = sizeof(struct tomoyo_mount_acl), +}; + +/** + * tomoyo_struct_used_by_io_buffer - Check whether the list element is used by /sys/kernel/security/tomoyo/ users or not. + * + * @element: Pointer to "struct list_head". + * + * Returns true if @element is used by /sys/kernel/security/tomoyo/ users, + * false otherwise. + */ +static bool tomoyo_struct_used_by_io_buffer(const struct list_head *element) +{ + struct tomoyo_io_buffer *head; + bool in_use = false; + + spin_lock(&tomoyo_io_buffer_list_lock); + list_for_each_entry(head, &tomoyo_io_buffer_list, list) { + head->users++; + spin_unlock(&tomoyo_io_buffer_list_lock); + if (mutex_lock_interruptible(&head->io_sem)) { + in_use = true; + goto out; + } + if (head->r.domain == element || head->r.group == element || + head->r.acl == element || &head->w.domain->list == element) + in_use = true; + mutex_unlock(&head->io_sem); +out: + spin_lock(&tomoyo_io_buffer_list_lock); + head->users--; + if (in_use) + break; + } + spin_unlock(&tomoyo_io_buffer_list_lock); + return in_use; +} + +/** + * tomoyo_name_used_by_io_buffer - Check whether the string is used by /sys/kernel/security/tomoyo/ users or not. + * + * @string: String to check. + * @size: Memory allocated for @string . + * + * Returns true if @string is used by /sys/kernel/security/tomoyo/ users, + * false otherwise. + */ +static bool tomoyo_name_used_by_io_buffer(const char *string, + const size_t size) +{ + struct tomoyo_io_buffer *head; + bool in_use = false; + + spin_lock(&tomoyo_io_buffer_list_lock); + list_for_each_entry(head, &tomoyo_io_buffer_list, list) { + int i; + head->users++; + spin_unlock(&tomoyo_io_buffer_list_lock); + if (mutex_lock_interruptible(&head->io_sem)) { + in_use = true; + goto out; + } + for (i = 0; i < TOMOYO_MAX_IO_READ_QUEUE; i++) { + const char *w = head->r.w[i]; + if (w < string || w > string + size) + continue; + in_use = true; + break; + } + mutex_unlock(&head->io_sem); +out: + spin_lock(&tomoyo_io_buffer_list_lock); + head->users--; + if (in_use) + break; + } + spin_unlock(&tomoyo_io_buffer_list_lock); + return in_use; +} + +/* Structure for garbage collection. */ struct tomoyo_gc { struct list_head list; enum tomoyo_policy_id type; + size_t size; struct list_head *element; }; -static LIST_HEAD(tomoyo_gc_queue); -static DEFINE_MUTEX(tomoyo_gc_mutex); +/* List of entries to be deleted. */ +static LIST_HEAD(tomoyo_gc_list); +/* Length of tomoyo_gc_list. */ +static int tomoyo_gc_list_len; /** * tomoyo_add_to_gc - Add an entry to to be deleted list. @@ -43,10 +153,42 @@ static bool tomoyo_add_to_gc(const int type, struct list_head *element) if (!entry) return false; entry->type = type; + if (type == TOMOYO_ID_ACL) + entry->size = tomoyo_acl_size[ + container_of(element, + typeof(struct tomoyo_acl_info), + list)->type]; + else if (type == TOMOYO_ID_NAME) + entry->size = strlen(container_of(element, + typeof(struct tomoyo_name), + head.list)->entry.name) + 1; + else + entry->size = tomoyo_element_size[type]; entry->element = element; - list_add(&entry->list, &tomoyo_gc_queue); + list_add(&entry->list, &tomoyo_gc_list); list_del_rcu(element); - return true; + return tomoyo_gc_list_len++ < 128; +} + +/** + * tomoyo_element_linked_by_gc - Validate next element of an entry. + * + * @element: Pointer to an element. + * @size: Size of @element in byte. + * + * Returns true if @element is linked by other elements in the garbage + * collector's queue, false otherwise. + */ +static bool tomoyo_element_linked_by_gc(const u8 *element, const size_t size) +{ + struct tomoyo_gc *p; + list_for_each_entry(p, &tomoyo_gc_list, list) { + const u8 *ptr = (const u8 *) p->element->next; + if (ptr < element || element + size < ptr) + continue; + return true; + } + return false; } /** @@ -151,6 +293,13 @@ static void tomoyo_del_acl(struct list_head *element) } } +/** + * tomoyo_del_domain - Delete members in "struct tomoyo_domain_info". + * + * @element: Pointer to "struct list_head". + * + * Returns true if deleted, false otherwise. + */ static bool tomoyo_del_domain(struct list_head *element) { struct tomoyo_domain_info *domain = @@ -360,13 +509,44 @@ unlock: mutex_unlock(&tomoyo_policy_lock); } -static void tomoyo_kfree_entry(void) +/** + * tomoyo_kfree_entry - Delete entries in tomoyo_gc_list. + * + * Returns true if some entries were kfree()d, false otherwise. + */ +static bool tomoyo_kfree_entry(void) { struct tomoyo_gc *p; struct tomoyo_gc *tmp; + bool result = false; - list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) { + list_for_each_entry_safe(p, tmp, &tomoyo_gc_list, list) { struct list_head *element = p->element; + + /* + * list_del_rcu() in tomoyo_add_to_gc() guarantees that the + * list element became no longer reachable from the list which + * the element was originally on (e.g. tomoyo_domain_list). + * Also, synchronize_srcu() in tomoyo_gc_thread() guarantees + * that the list element became no longer referenced by syscall + * users. + * + * However, there are three users which may still be using the + * list element. We need to defer until all of these users + * forget the list element. + * + * Firstly, defer until "struct tomoyo_io_buffer"->r.{domain, + * group,acl} and "struct tomoyo_io_buffer"->w.domain forget + * the list element. + */ + if (tomoyo_struct_used_by_io_buffer(element)) + continue; + /* + * Secondly, defer until all other elements in the + * tomoyo_gc_list list forget the list element. + */ + if (tomoyo_element_linked_by_gc((const u8 *) element, p->size)) + continue; switch (p->type) { case TOMOYO_ID_TRANSITION_CONTROL: tomoyo_del_transition_control(element); @@ -378,6 +558,14 @@ static void tomoyo_kfree_entry(void) tomoyo_del_manager(element); break; case TOMOYO_ID_NAME: + /* + * Thirdly, defer until all "struct tomoyo_io_buffer" + * ->r.w[] forget the list element. + */ + if (tomoyo_name_used_by_io_buffer( + container_of(element, typeof(struct tomoyo_name), + head.list)->entry.name, p->size)) + continue; tomoyo_del_name(element); break; case TOMOYO_ID_ACL: @@ -402,7 +590,10 @@ static void tomoyo_kfree_entry(void) tomoyo_memory_free(element); list_del(&p->list); kfree(p); + tomoyo_gc_list_len--; + result = true; } + return result; } /** @@ -418,25 +609,70 @@ static void tomoyo_kfree_entry(void) */ static int tomoyo_gc_thread(void *unused) { + /* Garbage collector thread is exclusive. */ + static DEFINE_MUTEX(tomoyo_gc_mutex); + if (!mutex_trylock(&tomoyo_gc_mutex)) + goto out; 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(); + do { + tomoyo_collect_entry(); + if (list_empty(&tomoyo_gc_list)) + break; + synchronize_srcu(&tomoyo_ss); + } while (tomoyo_kfree_entry()); + { + struct tomoyo_io_buffer *head; + struct tomoyo_io_buffer *tmp; + + spin_lock(&tomoyo_io_buffer_list_lock); + list_for_each_entry_safe(head, tmp, &tomoyo_io_buffer_list, + list) { + if (head->users) + continue; + list_del(&head->list); + kfree(head->read_buf); + kfree(head->write_buf); + kfree(head); } - mutex_unlock(&tomoyo_gc_mutex); + spin_unlock(&tomoyo_io_buffer_list_lock); } - do_exit(0); + mutex_unlock(&tomoyo_gc_mutex); +out: + /* This acts as do_exit(0). */ + return 0; } -void tomoyo_run_gc(void) +/** + * tomoyo_notify_gc - Register/unregister /sys/kernel/security/tomoyo/ users. + * + * @head: Pointer to "struct tomoyo_io_buffer". + * @is_register: True if register, false if unregister. + * + * Returns nothing. + */ +void tomoyo_notify_gc(struct tomoyo_io_buffer *head, const bool is_register) { - struct task_struct *task = kthread_create(tomoyo_gc_thread, NULL, - "GC for TOMOYO"); - if (!IS_ERR(task)) - wake_up_process(task); + bool is_write = false; + + spin_lock(&tomoyo_io_buffer_list_lock); + if (is_register) { + head->users = 1; + list_add(&head->list, &tomoyo_io_buffer_list); + } else { + is_write = head->write_buf != NULL; + if (!--head->users) { + list_del(&head->list); + kfree(head->read_buf); + kfree(head->write_buf); + kfree(head); + } + } + spin_unlock(&tomoyo_io_buffer_list_lock); + if (is_write) { + struct task_struct *task = kthread_create(tomoyo_gc_thread, + NULL, + "GC for TOMOYO"); + if (!IS_ERR(task)) + wake_up_process(task); + } } |
