Re: [PATCH for-next 6/7] RDMA/rtrs: Do not allow sessname to contain special symbols / and .

[Jack Wang <xjtuwjp@gmail.com>]

Leon Romanovsky <leon@kernel.org> 于2021年9月27日周一 下午2:23写道：
>
> On Wed, Sep 22, 2021 at 02:53:32PM +0200, Md Haris Iqbal wrote:
> > Allowing these characters in sessname can lead to unexpected results,
> > particularly because / is used as a separator between files in a path,
> > and . points to the current directory.
> >
> > Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
> > Reviewed-by: Gioh Kim <gi-oh.kim@ionos.com>
> > Reviewed-by: Aleksei Marov <aleksei.marov@ionos.com>
> > ---
> >  drivers/infiniband/ulp/rtrs/rtrs-clt.c | 6 ++++++
> >  drivers/infiniband/ulp/rtrs/rtrs-srv.c | 5 +++++
> >  2 files changed, 11 insertions(+)
>
> It will be safer if you check for only allowed symbols and disallow
> everything else. Check for: a-Z, 0-9 and "-".
>
Hi Leon,

Thanks for your suggestions.
The reasons we choose to do disallow only '/' and '.':
1 more flexible, most UNIX filenames allow any 8-bit set, except '/' and null.
2 matching for 2 characters is faster than checking all the allowed
symbols during session establishment.
3 we do use hostnameA@hostnameB for production usage right now, we
don't want to break the user space.

I hope this makes sense to you.

Regards!

>
> >
> > diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> > index bc8824b4ee0d..15c0077dd27e 100644
> > --- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> > +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> > @@ -2788,6 +2788,12 @@ struct rtrs_clt *rtrs_clt_open(struct rtrs_clt_ops *ops,
> >       struct rtrs_clt *clt;
> >       int err, i;
> >
> > +     if (strchr(sessname, '/') || strchr(sessname, '.')) {
> > +             pr_err("sessname cannot contain / and .\n");
> > +             err = -EINVAL;
> > +             goto out;
> > +     }
> > +
> >       clt = alloc_clt(sessname, paths_num, port, pdu_sz, ops->priv,
> >                       ops->link_ev,
> >                       reconnect_delay_sec,
> > diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv.c b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
> > index 078a1cbac90c..7df71f8cf149 100644
> > --- a/drivers/infiniband/ulp/rtrs/rtrs-srv.c
> > +++ b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
> > @@ -803,6 +803,11 @@ static int process_info_req(struct rtrs_srv_con *con,
> >               return err;
> >       }
> >
> > +     if (strchr(msg->sessname, '/') || strchr(msg->sessname, '.')) {
> > +             rtrs_err(s, "sessname cannot contain / and .\n");
> > +             return -EINVAL;
> > +     }
> > +
> >       if (exist_sessname(sess->srv->ctx,
> >                          msg->sessname, &sess->srv->paths_uuid)) {
> >               rtrs_err(s, "sessname is duplicated: %s\n", msg->sessname);
> > --
> > 2.25.1
> >