[PATCH] sanitize proc_sysctl

* keep references to ctl_table_head and ctl_table in /proc/sys inodes
* grab the former during operations, use the latter for access to
  entry if that succeeds
* have ->d_compare() check if table should be seen for one who does lookup;
  that allows us to avoid flipping inodes - if we have the same name resolve
  to different things, we'll just keep several dentries and ->d_compare()
  will reject the wrong ones.
* have ->lookup() and ->readdir() scan the table of our inode first, then
  walk all ctl_table_header and scan ->attached_by for those that are
  attached to our directory.
* implement ->getattr().
* get rid of insane amounts of tree-walking
* get rid of the need to know dentry in ->permission() and of the contortions
  induced by that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index f560d1705afe..fb61850d1cfc 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -282,11 +282,16 @@ union proc_op {
                 struct task_struct *task);
 };
 
+struct ctl_table_header;
+struct ctl_table;
+
 struct proc_inode {
         struct pid *pid;
         int fd;
         union proc_op op;
         struct proc_dir_entry *pde;
+        struct ctl_table_header *sysctl;
+        struct ctl_table *sysctl_entry;
         struct inode vfs_inode;
 };
 
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 3f6599aeb0db..d0437f36921f 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -961,6 +961,7 @@ struct ctl_table_header;
 
 extern void sysctl_head_get(struct ctl_table_header *);
 extern void sysctl_head_put(struct ctl_table_header *);
+extern int sysctl_is_seen(struct ctl_table_header *);
 extern struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *);
 extern struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev);
 extern struct ctl_table_header *__sysctl_head_next(struct nsproxy *namespaces,