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>

1 files changed, 50 insertions, 40 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) {
                 if (!ptr->is_deleted && !ptr->is_domain
                     && !strcmp(exe, ptr->manager->name)) {
                         found = true;
                         break;
                 }
         }
-        up_read(&tomoyo_policy_manager_list_lock);
         if (!found) { /* Reduce error messages. */
                 static pid_t last_pid;
                 const pid_t pid = current->pid;
@@ -1252,6 +1253,8 @@ static bool tomoyo_is_policy_manager(void)
  * @data: String to parse.
  *
  * Returns true on success, false otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static bool tomoyo_is_select_one(struct tomoyo_io_buffer *head,
                                  const char *data)
@@ -1267,11 +1270,8 @@ static bool tomoyo_is_select_one(struct tomoyo_io_buffer *head,
                         domain = tomoyo_real_domain(p);
                 read_unlock(&tasklist_lock);
         } else if (!strncmp(data, "domain=", 7)) {
-                if (tomoyo_is_domain_def(data + 7)) {
-                        down_read(&tomoyo_domain_list_lock);
+                if (tomoyo_is_domain_def(data + 7))
                         domain = tomoyo_find_domain(data + 7);
-                        up_read(&tomoyo_domain_list_lock);
-                }
         } else
                 return false;
         head->write_var1 = domain;
@@ -1285,13 +1285,11 @@ static bool tomoyo_is_select_one(struct tomoyo_io_buffer *head,
         if (domain) {
                 struct tomoyo_domain_info *d;
                 head->read_var1 = NULL;
-                down_read(&tomoyo_domain_list_lock);
-                list_for_each_entry(d, &tomoyo_domain_list, list) {
+                list_for_each_entry_rcu(d, &tomoyo_domain_list, list) {
                         if (d == domain)
                                 break;
                         head->read_var1 = &d->list;
                 }
-                up_read(&tomoyo_domain_list_lock);
                 head->read_var2 = NULL;
                 head->read_bit = 0;
                 head->read_step = 0;
@@ -1307,6 +1305,8 @@ static bool tomoyo_is_select_one(struct tomoyo_io_buffer *head,
  * @domainname: The name of domain.
  *
  * Returns 0.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_delete_domain(char *domainname)
 {
@@ -1317,7 +1317,7 @@ static int tomoyo_delete_domain(char *domainname)
         tomoyo_fill_path_info(&name);
         down_write(&tomoyo_domain_list_lock);
         /* Is there an active domain? */
-        list_for_each_entry(domain, &tomoyo_domain_list, list) {
+        list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
                 /* Never delete tomoyo_kernel_domain */
                 if (domain == &tomoyo_kernel_domain)
                         continue;
@@ -1337,6 +1337,8 @@ static int tomoyo_delete_domain(char *domainname)
  * @head: Pointer to "struct tomoyo_io_buffer".
  *
  * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_write_domain_policy(struct tomoyo_io_buffer *head)
 {
@@ -1359,11 +1361,9 @@ static int tomoyo_write_domain_policy(struct tomoyo_io_buffer *head)
                 domain = NULL;
                 if (is_delete)
                         tomoyo_delete_domain(data);
-                else if (is_select) {
-                        down_read(&tomoyo_domain_list_lock);
+                else if (is_select)
                         domain = tomoyo_find_domain(data);
-                        up_read(&tomoyo_domain_list_lock);
-                } else
+                else
                         domain = tomoyo_find_or_assign_new_domain(data, 0);
                 head->write_var1 = domain;
                 return 0;
@@ -1508,6 +1508,8 @@ static bool tomoyo_print_entry(struct tomoyo_io_buffer *head,
  * @head: Pointer to "struct tomoyo_io_buffer".
  *
  * Returns 0.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_read_domain_policy(struct tomoyo_io_buffer *head)
 {
@@ -1519,7 +1521,6 @@ static int tomoyo_read_domain_policy(struct tomoyo_io_buffer *head)
                 return 0;
         if (head->read_step == 0)
                 head->read_step = 1;
-        down_read(&tomoyo_domain_list_lock);
         list_for_each_cookie(dpos, head->read_var1, &tomoyo_domain_list) {
                 struct tomoyo_domain_info *domain;
                 const char *quota_exceeded = "";
@@ -1552,7 +1553,6 @@ acl_loop:
                 if (head->read_step == 3)
                         goto tail_mark;
                 /* Print ACL entries in the domain. */
-                down_read(&tomoyo_domain_acl_info_list_lock);
                 list_for_each_cookie(apos, head->read_var2,
                                      &domain->acl_info_list) {
                         struct tomoyo_acl_info *ptr
@@ -1562,7 +1562,6 @@ acl_loop:
                         if (!done)
                                 break;
                 }
-                up_read(&tomoyo_domain_acl_info_list_lock);
                 if (!done)
                         break;
                 head->read_step = 3;
@@ -1574,7 +1573,6 @@ tail_mark:
                 if (head->read_single_domain)
                         break;
         }
-        up_read(&tomoyo_domain_list_lock);
         head->read_eof = done;
         return 0;
 }
@@ -1590,6 +1588,8 @@ tail_mark:
  *
  *     ( echo "select " $domainname; echo "use_profile " $profile ) |
  *     /usr/lib/ccs/loadpolicy -d
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_write_domain_profile(struct tomoyo_io_buffer *head)
 {
@@ -1601,9 +1601,7 @@ static int tomoyo_write_domain_profile(struct tomoyo_io_buffer *head)
         if (!cp)
                 return -EINVAL;
         *cp = '\0';
-        down_read(&tomoyo_domain_list_lock);
         domain = tomoyo_find_domain(cp + 1);
-        up_read(&tomoyo_domain_list_lock);
         if (strict_strtoul(data, 10, &profile))
                 return -EINVAL;
         if (domain && profile < TOMOYO_MAX_PROFILES
@@ -1625,6 +1623,8 @@ static int tomoyo_write_domain_profile(struct tomoyo_io_buffer *head)
  *     awk ' { if ( domainname == "" ) { if ( $1 == "<kernel>" )
  *     domainname = $0; } else if ( $1 == "use_profile" ) {
  *     print $2 " " domainname; domainname = ""; } } ; '
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_read_domain_profile(struct tomoyo_io_buffer *head)
 {
@@ -1633,7 +1633,6 @@ static int tomoyo_read_domain_profile(struct tomoyo_io_buffer *head)
 
         if (head->read_eof)
                 return 0;
-        down_read(&tomoyo_domain_list_lock);
         list_for_each_cookie(pos, head->read_var1, &tomoyo_domain_list) {
                 struct tomoyo_domain_info *domain;
                 domain = list_entry(pos, struct tomoyo_domain_info, list);
@@ -1644,7 +1643,6 @@ static int tomoyo_read_domain_profile(struct tomoyo_io_buffer *head)
                 if (!done)
                         break;
         }
-        up_read(&tomoyo_domain_list_lock);
         head->read_eof = done;
         return 0;
 }
@@ -1701,6 +1699,8 @@ static int tomoyo_read_pid(struct tomoyo_io_buffer *head)
  * @head: Pointer to "struct tomoyo_io_buffer".
  *
  * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_write_exception_policy(struct tomoyo_io_buffer *head)
 {
@@ -1735,6 +1735,8 @@ static int tomoyo_write_exception_policy(struct tomoyo_io_buffer *head)
  * @head: Pointer to "struct tomoyo_io_buffer".
  *
  * Returns 0 on success, -EINVAL otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_read_exception_policy(struct tomoyo_io_buffer *head)
 {
@@ -1864,15 +1866,13 @@ void tomoyo_load_policy(const char *filename)
         tomoyo_policy_loaded = true;
         { /* Check all profiles currently assigned to domains are defined. */
                 struct tomoyo_domain_info *domain;
-                down_read(&tomoyo_domain_list_lock);
-                list_for_each_entry(domain, &tomoyo_domain_list, list) {
+                list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
                         const u8 profile = domain->profile;
                         if (tomoyo_profile_ptr[profile])
                                 continue;
                         panic("Profile %u (used by '%s') not defined.\n",
                               profile, domain->domainname->name);
                 }
-                up_read(&tomoyo_domain_list_lock);
         }
 }
 
@@ -1920,6 +1920,8 @@ static int tomoyo_read_self_domain(struct tomoyo_io_buffer *head)
  * @file: Pointer to "struct file".
  *
  * Associates policy handler and returns 0 on success, -ENOMEM otherwise.
+ *
+ * Caller acquires tomoyo_read_lock().
  */
 static int tomoyo_open_control(const u8 type, struct file *file)
 {
@@ -2005,6 +2007,7 @@ static int tomoyo_open_control(const u8 type, struct file *file)
                         return -ENOMEM;
                 }
         }
+        head->reader_idx = tomoyo_read_lock();
         file->private_data = head;
         /*
          * Call the handler now if the file is
@@ -2026,6 +2029,8 @@ static int tomoyo_open_control(const u8 type, struct file *file)
  * @buffer_len: Size of @buffer.
  *
  * Returns bytes read on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_read_control(struct file *file, char __user *buffer,
                                const int buffer_len)
@@ -2069,6 +2074,8 @@ static int tomoyo_read_control(struct file *file, char __user *buffer,
  * @buffer_len: Size of @buffer.
  *
  * Returns @buffer_len on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
  */
 static int tomoyo_write_control(struct file *file, const char __user *buffer,
                                 const int buffer_len)
@@ -2119,11 +2126,14 @@ static int tomoyo_write_control(struct file *file, const char __user *buffer,
  * @file: Pointer to "struct file".
  *
  * Releases memory and returns 0.
+ *
+ * Caller looses tomoyo_read_lock().
  */
 static int tomoyo_close_control(struct file *file)
 {
         struct tomoyo_io_buffer *head = file->private_data;
 
+        tomoyo_read_unlock(head->reader_idx);
         /* Release memory used for policy I/O. */
         tomoyo_free(head->read_buf);
         head->read_buf = NULL;