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

[Luis Henriques <lhenriques@suse.de>]

On Fri, Jul 02, 2021 at 04:40:18PM +0530, Venky Shankar wrote:
> 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.

Ah, sure!  I didn't meant you'd need to change the messenger to handle it
(as I'm not even sure it's the messenger or the mons client that require
changes).  But I also don't think that this patchset can be merged without
making sure we can handle a bad fsid correctly and without all this noise.

Cheers,
--
Luís

> 
> >
> > 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
>