Re: [patch 00/13] vfs: add helpers to check r/o bind mounts

From: Miklos Szeredi
Date: Thu Apr 24 2008 - 11:28:57 EST


> > > > > RTFS. permission() doesn't do "is that vfsmount read-only" checks, exactly
> > > > > because it's 100% bogus - either you cover it with entire area where we
> > > > > are guaranteed to stay r/w, or it's by definition racy.
> > > >
> > > > I know that.
> > > >
> > > > That does not mean, that fh_verify() needs to do vfsmount r/o checks.
> > > > AFAICS it's perfectly OK to do that later, around the vfs_ call.
> > >
> > > ... and around everything else that happens to be done after fh_verify
> > > for write access, surely?
> >
> > What in particular? You have managed to avoid answering this question
> > for the last...I don't know how many emails.
>
> Oh, for fuck sake... grep and ye shall see. Right next to setattr we
> have nfsd4_set_nfs4_acl(), with pair of set_nfsv4_acl_one(). I'd rather
> have those two covered by a single will/wont range, TYVM.
>
> nfsd_create() will happily do vfs_mkdir() and nfsd_create_setattr(). Ditto.

Please read the patches? I've left exactly these
mnt_want_write/drop_write() calls in place, and removed all the
others.

> And while we are at it, losing the check for r/o in fh_verify() will sure
> as hell require at least handling it separately on the normal write path.

Umm, no, dentry_open() will do that.

>
> > > Note that e.g. nfsd_setattr() does _not_ call
> > > vfs_<anything>()...
> >
> > Yes it does: notify_change(). It's vfs_setattr() under a pseudonym.
>
> Are you going to move the will/wont in there? Because there's a bunch of
> stuff in fs/open.c that will disagree...

Please read the patches, won't you?

Miklos
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