TOMOYO: Change list iterator.

Change list_for_each_cookie to

(1) start from current position rather than next position
(2) remove temporary cursor
(3) check that srcu_read_lock() is held

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

2 files changed, 34 insertions, 57 deletions

diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index 6568ef18112b..2a5330ec06c9 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -507,16 +507,14 @@ static int tomoyo_write_manager_policy(struct tomoyo_io_buffer *head)
  */
 static void tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
 {
-        struct list_head *pos;
         bool done = true;
 
         if (head->read_eof)
                 return;
-        list_for_each_cookie(pos, head->read_var2,
+        list_for_each_cookie(head->read_var2,
                              &tomoyo_policy_list[TOMOYO_ID_MANAGER]) {
-                struct tomoyo_policy_manager_entry *ptr;
-                ptr = list_entry(pos, struct tomoyo_policy_manager_entry,
-                                 head.list);
+                struct tomoyo_policy_manager_entry *ptr =
+                        list_entry(head->read_var2, typeof(*ptr), head.list);
                 if (ptr->head.is_deleted)
                         continue;
                 done = tomoyo_io_printf(head, "%s\n", ptr->manager->name);
@@ -590,8 +588,7 @@ static bool tomoyo_policy_manager(void)
  *
  * Caller holds tomoyo_read_lock().
  */
-static bool tomoyo_select_one(struct tomoyo_io_buffer *head,
-                                 const char *data)
+static bool tomoyo_select_one(struct tomoyo_io_buffer *head, const char *data)
 {
         unsigned int pid;
         struct tomoyo_domain_info *domain = NULL;
@@ -623,20 +620,12 @@ static bool tomoyo_select_one(struct tomoyo_io_buffer *head,
         tomoyo_io_printf(head, "# select %s\n", data);
         head->read_single_domain = true;
         head->read_eof = !domain;
-        if (domain) {
-                struct tomoyo_domain_info *d;
-                head->read_var1 = NULL;
-                list_for_each_entry_rcu(d, &tomoyo_domain_list, list) {
-                        if (d == domain)
-                                break;
-                        head->read_var1 = &d->list;
-                }
-                head->read_var2 = NULL;
-                head->read_bit = 0;
-                head->read_step = 0;
-                if (domain->is_deleted)
-                        tomoyo_io_printf(head, "# This is a deleted domain.\n");
-        }
+        head->read_var1 = &domain->list;
+        head->read_var2 = NULL;
+        head->read_bit = 0;
+        head->read_step = 0;
+        if (domain && domain->is_deleted)
+                tomoyo_io_printf(head, "# This is a deleted domain.\n");
         return true;
 }
 
@@ -972,20 +961,18 @@ static bool tomoyo_print_entry(struct tomoyo_io_buffer *head,
  */
 static void tomoyo_read_domain_policy(struct tomoyo_io_buffer *head)
 {
-        struct list_head *dpos;
-        struct list_head *apos;
         bool done = true;
 
         if (head->read_eof)
                 return;
         if (head->read_step == 0)
                 head->read_step = 1;
-        list_for_each_cookie(dpos, head->read_var1, &tomoyo_domain_list) {
-                struct tomoyo_domain_info *domain;
+        list_for_each_cookie(head->read_var1, &tomoyo_domain_list) {
+                struct tomoyo_domain_info *domain =
+                        list_entry(head->read_var1, typeof(*domain), list);
                 const char *quota_exceeded = "";
                 const char *transition_failed = "";
                 const char *ignore_global_allow_read = "";
-                domain = list_entry(dpos, struct tomoyo_domain_info, list);
                 if (head->read_step != 1)
                         goto acl_loop;
                 if (domain->is_deleted && !head->read_single_domain)
@@ -1011,17 +998,17 @@ acl_loop:
                 if (head->read_step == 3)
                         goto tail_mark;
                 /* Print ACL entries in the domain. */
-                list_for_each_cookie(apos, head->read_var2,
+                list_for_each_cookie(head->read_var2,
                                      &domain->acl_info_list) {
-                        struct tomoyo_acl_info *ptr
-                                = list_entry(apos, struct tomoyo_acl_info,
-                                             list);
+                        struct tomoyo_acl_info *ptr =
+                                list_entry(head->read_var2, typeof(*ptr), list);
                         done = tomoyo_print_entry(head, ptr);
                         if (!done)
                                 break;
                 }
                 if (!done)
                         break;
+                head->read_var2 = NULL;
                 head->read_step = 3;
 tail_mark:
                 done = tomoyo_io_printf(head, "\n");
@@ -1085,14 +1072,13 @@ static int tomoyo_write_domain_profile(struct tomoyo_io_buffer *head)
  */
 static void tomoyo_read_domain_profile(struct tomoyo_io_buffer *head)
 {
-        struct list_head *pos;
         bool done = true;
 
         if (head->read_eof)
                 return;
-        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);
+        list_for_each_cookie(head->read_var1, &tomoyo_domain_list) {
+                struct tomoyo_domain_info *domain =
+                        list_entry(head->read_var1, typeof(*domain), list);
                 if (domain->is_deleted)
                         continue;
                 done = tomoyo_io_printf(head, "%u %s\n", domain->profile,
@@ -1245,19 +1231,16 @@ static const char *tomoyo_group_name[TOMOYO_MAX_GROUP] = {
  */
 static bool tomoyo_read_group(struct tomoyo_io_buffer *head, const int idx)
 {
-        struct list_head *gpos;
-        struct list_head *mpos;
         const char *w[3] = { "", "", "" };
         w[0] = tomoyo_group_name[idx];
-        list_for_each_cookie(gpos, head->read_var1, &tomoyo_group_list[idx]) {
+        list_for_each_cookie(head->read_var1, &tomoyo_group_list[idx]) {
                 struct tomoyo_group *group =
-                        list_entry(gpos, struct tomoyo_group, list);
+                        list_entry(head->read_var1, typeof(*group), list);
                 w[1] = group->group_name->name;
-                list_for_each_cookie(mpos, head->read_var2,
-                                     &group->member_list) {
+                list_for_each_cookie(head->read_var2, &group->member_list) {
                         char buffer[128];
                         struct tomoyo_acl_head *ptr =
-                                list_entry(mpos, struct tomoyo_acl_head, list);
+                                list_entry(head->read_var2, typeof(*ptr), list);
                         if (ptr->is_deleted)
                                 continue;
                         if (idx == TOMOYO_PATH_GROUP) {
@@ -1276,7 +1259,9 @@ static bool tomoyo_read_group(struct tomoyo_io_buffer *head, const int idx)
                                               w[2]))
                                 return false;
                 }
+                head->read_var2 = NULL;
         }
+        head->read_var1 = NULL;
         return true;
 }
 
@@ -1292,11 +1277,10 @@ static bool tomoyo_read_group(struct tomoyo_io_buffer *head, const int idx)
  */
 static bool tomoyo_read_policy(struct tomoyo_io_buffer *head, const int idx)
 {
-        struct list_head *pos;
-        list_for_each_cookie(pos, head->read_var2, &tomoyo_policy_list[idx]) {
+        list_for_each_cookie(head->read_var2, &tomoyo_policy_list[idx]) {
                 const char *w[4] = { "", "", "", "" };
-                struct tomoyo_acl_head *acl = container_of(pos, typeof(*acl),
-                                                           list);
+                struct tomoyo_acl_head *acl =
+                        container_of(head->read_var2, typeof(*acl), list);
                 if (acl->is_deleted)
                         continue;
                 switch (idx) {
@@ -1354,6 +1338,7 @@ static bool tomoyo_read_policy(struct tomoyo_io_buffer *head, const int idx)
                                       w[3]))
                         return false;
         }
+        head->read_var2 = NULL;
         return true;
 }
 
diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h
index 1277724edae4..cdc9ef56fd86 100644
--- a/security/tomoyo/common.h
+++ b/security/tomoyo/common.h
@@ -1023,19 +1023,11 @@ static inline bool tomoyo_same_number_union
 /**
  * list_for_each_cookie - iterate over a list with cookie.
  * @pos:        the &struct list_head to use as a loop cursor.
- * @cookie:     the &struct list_head to use as a cookie.
  * @head:       the head for your list.
- *
- * Same with list_for_each_rcu() except that this primitive uses @cookie
- * so that we can continue iteration.
- * @cookie must be NULL when iteration starts, and @cookie will become
- * NULL when iteration finishes.
  */
-#define list_for_each_cookie(pos, cookie, head)                         \
-        for (({ if (!cookie)                                            \
-                                     cookie = head; }),                 \
-                     pos = rcu_dereference((cookie)->next);             \
-             prefetch(pos->next), pos != (head) || ((cookie) = NULL);   \
-             (cookie) = pos, pos = rcu_dereference(pos->next))
+#define list_for_each_cookie(pos, head)                                 \
+        if (!pos)                                                       \
+                pos =  srcu_dereference((head)->next, &tomoyo_ss);      \
+        for ( ; pos != (head); pos = srcu_dereference(pos->next, &tomoyo_ss))
 
 #endif /* !defined(_SECURITY_TOMOYO_COMMON_H) */