TOMOYO: Use RCU primitives for list operation

Replace list operation with RCU primitives and replace
down_read()/up_read() with srcu_read_lock()/srcu_read_unlock().

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>

6 files changed, 207 insertions, 112 deletions

diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index 6c6061682438..f01b9364db2d 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -365,10 +365,9 @@ bool tomoyo_is_domain_def(const unsigned char *buffer)
  *
  * @domainname: The domainname to find.
  *
- * Caller must call down_read(&tomoyo_domain_list_lock); or
- * down_write(&tomoyo_domain_list_lock); .
- *
  * Returns pointer to "struct tomoyo_domain_info" if found, NULL otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 struct tomoyo_domain_info *tomoyo_find_domain(const char *domainname)
 {
@@ -377,7 +376,7 @@ struct tomoyo_domain_info *tomoyo_find_domain(const char *domainname)
 
         name.name = domainname;
         tomoyo_fill_path_info(&name);
-        list_for_each_entry(domain, &tomoyo_domain_list, list) {
+        list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
                 if (!domain->is_deleted &&
                     !tomoyo_pathcmp(&name, domain->domainname))
                         return domain;
@@ -829,6 +828,8 @@ bool tomoyo_verbose_mode(const struct tomoyo_domain_info *domain)
  * @domain: Pointer to "struct tomoyo_domain_info".
  *
  * Returns true if the domain is not exceeded quota, false otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 bool tomoyo_domain_quota_is_ok(struct tomoyo_domain_info * const domain)
 {
@@ -837,8 +838,7 @@ bool tomoyo_domain_quota_is_ok(struct tomoyo_domain_info * const domain)
 
         if (!domain)
                 return true;
-        down_read(&tomoyo_domain_acl_info_list_lock);
-        list_for_each_entry(ptr, &domain->acl_info_list, list) {
+        list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
                 if (ptr->type & TOMOYO_ACL_DELETED)
                         continue;
                 switch (tomoyo_acl_type2(ptr)) {
@@ -866,7 +866,6 @@ bool tomoyo_domain_quota_is_ok(struct tomoyo_domain_info * const domain)
                         break;
                 }
         }
-        up_read(&tomoyo_domain_acl_info_list_lock);
         if (count < tomoyo_check_flags(domain, TOMOYO_MAX_ACCEPT_ENTRY))
                 return true;
         if (!domain->quota_warned) {
@@ -1096,6 +1095,8 @@ static DECLARE_RWSEM(tomoyo_policy_manager_list_lock);
  * @is_delete: True if it is a delete request.
  *
  * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_update_manager_entry(const char *manager,
                                        const bool is_delete)
@@ -1118,7 +1119,7 @@ static int tomoyo_update_manager_entry(const char *manager,
         if (!saved_manager)
                 return -ENOMEM;
         down_write(&tomoyo_policy_manager_list_lock);
-        list_for_each_entry(ptr, &tomoyo_policy_manager_list, list) {
+        list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
                 if (ptr->manager != saved_manager)
                         continue;
                 ptr->is_deleted = is_delete;
@@ -1134,7 +1135,7 @@ static int tomoyo_update_manager_entry(const char *manager,
                 goto out;
         new_entry->manager = saved_manager;
         new_entry->is_domain = is_domain;
-        list_add_tail(&new_entry->list, &tomoyo_policy_manager_list);
+        list_add_tail_rcu(&new_entry->list, &tomoyo_policy_manager_list);
         error = 0;
  out:
         up_write(&tomoyo_policy_manager_list_lock);
@@ -1147,6 +1148,8 @@ static int tomoyo_update_manager_entry(const char *manager,
  * @head: Pointer to "struct tomoyo_io_buffer".
  *
  * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_write_manager_policy(struct tomoyo_io_buffer *head)
 {
@@ -1166,6 +1169,8 @@ static int tomoyo_write_manager_policy(struct tomoyo_io_buffer *head)
  * @head: Pointer to "struct tomoyo_io_buffer".
  *
  * Returns 0.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
 {
@@ -1174,7 +1179,6 @@ static int tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
 
         if (head->read_eof)
                 return 0;
-        down_read(&tomoyo_policy_manager_list_lock);
         list_for_each_cookie(pos, head->read_var2,
                              &tomoyo_policy_manager_list) {
                 struct tomoyo_policy_manager_entry *ptr;
@@ -1186,7 +1190,6 @@ static int tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
                 if (!done)
                         break;
         }
-        up_read(&tomoyo_policy_manager_list_lock);
         head->read_eof = done;
         return 0;
 }
@@ -1196,6 +1199,8 @@ static int tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
  *
  * Returns true if the current process is permitted to modify policy
  * via /sys/kernel/security/tomoyo/ interface.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static bool tomoyo_is_policy_manager(void)
 {
@@ -1209,29 +1214,25 @@ static bool tomoyo_is_policy_manager(void)
                 return true;
         if (!tomoyo_manage_by_non_root && (task->cred->uid || task->cred->euid))
                 return false;
-        down_read(&tomoyo_policy_manager_list_lock);
-        list_for_each_entry(ptr, &tomoyo_policy_manager_list, list) {
+        list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
                 if (!ptr->is_deleted && ptr->is_domain
                     && !tomoyo_pathcmp(domainname, ptr->manager)) {
                         found = true;
                         break;
                 }
         }
-        up_read(&tomoyo_policy_manager_list_lock);
         if (found)
                 return true;
         exe = tomoyo_get_exe();
         if (!exe)
                 return false;
-        down_read(&tomoyo_policy_manager_list_lock);
-        list_for_each_entry(ptr, &tomoyo_policy_manager_list, list) {
+        list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {