vfs: re-introduce MAY_CHDIR

Currently MAY_ACCESS means that filesystems must check the permissions
right then and not rely on cached results or the results of future
operations on the object.  This can be because of a call to sys_access() or
because of a call to chdir() which needs to check search without relying on
any future operations inside that dir.  I plan to use MAY_ACCESS for other
purposes in the security system, so I split the MAY_ACCESS and the
MAY_CHDIR cases.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by:  Stephen D. Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/open.c b/fs/open.c
index a54ed85209c1..0d1fa3dc0efb 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -366,7 +366,7 @@ SYSCALL_DEFINE1(chdir, const char __user *, filename)
         if (error)
                 goto out;
 
-        error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
+        error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
         if (error)
                 goto dput_and_out;
 
@@ -395,7 +395,7 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd)
         if (!S_ISDIR(inode->i_mode))
                 goto out_putf;
 
-        error = inode_permission(inode, MAY_EXEC | MAY_ACCESS);
+        error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
         if (!error)
                 set_fs_pwd(current->fs, &file->f_path);
 out_putf:
@@ -413,7 +413,7 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
         if (error)
                 goto out;
 
-        error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
+        error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
         if (error)
                 goto dput_and_out;