Re: [PATCH 2/3] integrity: Linux Integrity Module(LIM)

Mimi Zohar
2008-10-24T14:48:11Z

On Tue, 2008-10-14 at 09:28 -0400, Christoph Hellwig wrote:
> > int vfs_permission(struct nameidata *nd, int mask)
> > {
> > - return inode_permission(nd->path.dentry->d_inode, mask);
> > + int retval;
> > +
> > + retval = inode_permission(nd->path.dentry->d_inode, mask);
> > + if (retval)
> > + return retval;
> > + return integrity_inode_permission(NULL, &nd->path,
> > + mask & (MAY_READ | MAY_WRITE |
> > + MAY_EXEC));
> > }
> >
> > /**
> > @@ -306,7 +314,14 @@ int vfs_permission(struct nameidata *nd, int mask)
> > */
> > int file_permission(struct file *file, int mask)
> > {
> > - return inode_permission(file->f_path.dentry->d_inode, mask);
> > + int retval;
> > +
> > + retval = inode_permission(file->f_path.dentry->d_inode, mask);
> > + if (retval)
> > + return retval;
> > + return integrity_inode_permission(file, NULL,
> > + mask & (MAY_READ | MAY_WRITE |
> > + MAY_EXEC));
>
> Please don't add anything here as these two wrappers will go away.

Ok.

> Please only make decisions based on what you get in inode_permission().

Is there any way to read a file, in order to calculate a hash, based
just on an inode and a mask? As far as I'm aware, either a file, or a
dentry and vfsmount structures, are needed. Previously, only the
dentry, not the vfsmount, was required, which is accessible from the
inode.

Without access to the vfsmount in inode_permission(), as
vfs_permission() is going away, the only option I see is to move the
integrity_inode_permission() call up a level to may_open(), after the
call to vfs_permission(). Would this be acceptable? (And change the
hook name to integrity_may_open.)

Mimi