On 8/15/2012 8:48 AM, Miklos Szeredi wrote: > From: Andy Whitcroft <[email protected]> > > 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. > > Switch over to __inode_permissions. > > Signed-off-by: Andy Whitcroft <[email protected]> > Signed-off-by: Miklos Szeredi <[email protected]> > --- > 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 [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
