On Wed, Aug 15, 2012 at 09:59:51AM -0700, Casey Schaufler wrote: > On 8/15/2012 8:48 AM, Miklos Szeredi wrote: > > From: Andy Whitcroft <a...@canonical.com> > > > > When checking permissions on an overlayfs inode we do not take into > > account either device cgroup restrictions nor security permissions. > > This allows a user to mount an overlayfs layer over a restricted device > > directory and by pass those permissions to open otherwise restricted > > files. > > Why is this a good idea? Either you're not including enough context > about the conditions under which this can occur, or you're suggesting > the introduction of a trivial mechanism for bypassing all file access > controls. This does not seem right.
It is stating that the unprotected case is how things was before this patch switches us over to __inode_permisssions. The patch is closing the hole indicated. -apw > > > > Switch over to __inode_permissions. > > > > Signed-off-by: Andy Whitcroft <a...@canonical.com> > > Signed-off-by: Miklos Szeredi <mszer...@suse.cz> > > --- > > fs/overlayfs/inode.c | 12 +----------- > > 1 files changed, 1 insertions(+), 11 deletions(-) > > > > diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c > > index e854720..f3a534f 100644 > > --- a/fs/overlayfs/inode.c > > +++ b/fs/overlayfs/inode.c > > @@ -100,19 +100,9 @@ int ovl_permission(struct inode *inode, int mask) > > if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) && > > (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) > > goto out_dput; > > - > > - /* > > - * Nobody gets write access to an immutable file. > > - */ > > - err = -EACCES; > > - if (IS_IMMUTABLE(realinode)) > > - goto out_dput; > > } > > > > - if (realinode->i_op->permission) > > - err = realinode->i_op->permission(realinode, mask); > > - else > > - err = generic_permission(realinode, mask); > > + err = __inode_permission(realinode, mask); > > out_dput: > > dput(alias); > > return err; > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
