Re: [PATCH v2 2/4] ceph: validate cluster FSID for new device syntax

[Venky Shankar <vshankar@redhat.com>]

On Fri, Jul 2, 2021 at 4:14 PM Luis Henriques <lhenriques@suse.de> wrote:
>
> On Fri, Jul 02, 2021 at 12:18:19PM +0530, Venky Shankar wrote:
> > The new device syntax requires the cluster FSID as part
> > of the device string. Use this FSID to verify if it matches
> > the cluster FSID we get back from the monitor, failing the
> > mount on mismatch.
> >
> > Also, rename parse_fsid() to ceph_parse_fsid() as it is too
> > generic.
> >
> > Signed-off-by: Venky Shankar <vshankar@redhat.com>
> > ---
> >  fs/ceph/super.c              | 9 +++++++++
> >  fs/ceph/super.h              | 1 +
> >  include/linux/ceph/libceph.h | 1 +
> >  net/ceph/ceph_common.c       | 5 +++--
> >  4 files changed, 14 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> > index 0b324e43c9f4..03e5f4bb2b6f 100644
> > --- a/fs/ceph/super.c
> > +++ b/fs/ceph/super.c
> > @@ -268,6 +268,9 @@ static int ceph_parse_new_source(const char *dev_name, const char *dev_name_end,
> >       if (!fs_name_start)
> >               return invalfc(fc, "missing file system name");
> >
> > +     if (ceph_parse_fsid(fsid_start, &fsopt->fsid))
> > +             return invalfc(fc, "invalid fsid format");
> > +
> >       ++fs_name_start; /* start of file system name */
> >       fsopt->mds_namespace = kstrndup(fs_name_start,
> >                                       dev_name_end - fs_name_start, GFP_KERNEL);
> > @@ -750,6 +753,12 @@ static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt,
> >       }
> >       opt = NULL; /* fsc->client now owns this */
> >
> > +     /* help learn fsid */
> > +     if (fsopt->new_dev_syntax) {
> > +             ceph_check_fsid(fsc->client, &fsopt->fsid);
>
> This call to ceph_check_fsid() made me wonder what would happen if I use
> the wrong fsid with the new syntax.  And the result is:
>
> [   41.882334] libceph: mon0 (1)192.168.155.1:40594 session established
> [   41.884537] libceph: bad fsid, had d52783e6-efc2-4dce-ad01-aa3272fa5f66 got 90bdb539-9d95-402e-8f23-b0e26cba8b1b
> [   41.885955] libceph: bad fsid, had d52783e6-efc2-4dce-ad01-aa3272fa5f66 got 90bdb539-9d95-402e-8f23-b0e26cba8b1b
> [   41.889313] libceph: bad fsid, had d52783e6-efc2-4dce-ad01-aa3272fa5f66 got 90bdb539-9d95-402e-8f23-b0e26cba8b1b
> [   41.892578] libceph: osdc handle_map corrupt msg
>
> ... followed by a msg dump.
>
> I guess this means that manually setting the fsid requires changes to the
> messenger (I've only tested with v1) so that it gracefully handles this
> scenario.

Yes, this results in a big dump of messages. I haven't looked at
gracefully handling these.

I'm not sure if it needs to be done in these set of patches though.

>
> Cheers,
> --
> Luís
>
> > +             fsc->client->have_fsid = true;
> > +     }
> > +
> >       fsc->client->extra_mon_dispatch = extra_mon_dispatch;
> >       ceph_set_opt(fsc->client, ABORT_ON_FULL);
> >
> > diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> > index 8f71184b7c85..ce5fb90a01a4 100644
> > --- a/fs/ceph/super.h
> > +++ b/fs/ceph/super.h
> > @@ -99,6 +99,7 @@ struct ceph_mount_options {
> >       char *server_path;    /* default NULL (means "/") */
> >       char *fscache_uniq;   /* default NULL */
> >       char *mon_addr;
> > +     struct ceph_fsid fsid;
> >  };
> >
> >  struct ceph_fs_client {
> > diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
> > index 409d8c29bc4f..75d059b79d90 100644
> > --- a/include/linux/ceph/libceph.h
> > +++ b/include/linux/ceph/libceph.h
> > @@ -296,6 +296,7 @@ extern bool libceph_compatible(void *data);
> >  extern const char *ceph_msg_type_name(int type);
> >  extern int ceph_check_fsid(struct ceph_client *client, struct ceph_fsid *fsid);
> >  extern void *ceph_kvmalloc(size_t size, gfp_t flags);
> > +extern int ceph_parse_fsid(const char *str, struct ceph_fsid *fsid);
> >
> >  struct fs_parameter;
> >  struct fc_log;
> > diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c
> > index 97d6ea763e32..da480757fcca 100644
> > --- a/net/ceph/ceph_common.c
> > +++ b/net/ceph/ceph_common.c
> > @@ -217,7 +217,7 @@ void *ceph_kvmalloc(size_t size, gfp_t flags)
> >       return p;
> >  }
> >
> > -static int parse_fsid(const char *str, struct ceph_fsid *fsid)
> > +int ceph_parse_fsid(const char *str, struct ceph_fsid *fsid)
> >  {
> >       int i = 0;
> >       char tmp[3];
> > @@ -247,6 +247,7 @@ static int parse_fsid(const char *str, struct ceph_fsid *fsid)
> >       dout("parse_fsid ret %d got fsid %pU\n", err, fsid);
> >       return err;
> >  }
> > +EXPORT_SYMBOL(ceph_parse_fsid);
> >
> >  /*
> >   * ceph options
> > @@ -465,7 +466,7 @@ int ceph_parse_param(struct fs_parameter *param, struct ceph_options *opt,
> >               break;
> >
> >       case Opt_fsid:
> > -             err = parse_fsid(param->string, &opt->fsid);
> > +             err = ceph_parse_fsid(param->string, &opt->fsid);
> >               if (err) {
> >                       error_plog(&log, "Failed to parse fsid: %d", err);
> >                       return err;
> > --
> > 2.27.0
> >
>


-- 
Cheers,
Venky