From: Seth Forshee <seth.forshee@canonical.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Serge H. Hallyn" <serge.hallyn@ubuntu.com>,
Michael j Theall <mtheall@us.ibm.com>,
fuse-devel@lists.sourceforge.net,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
seth.forshee@canonical.com
Subject: Re: [PATCH v5 4/4] fuse: Allow user namespace mounts
Date: Wed, 22 Oct 2014 19:22:00 -0500 [thread overview]
Message-ID: <20141023002200.GA138443@ubuntu-hedt> (raw)
In-Reply-To: <CALCETrV_4euS+iDi3imBvBW3L7sutQ6kGJ1Z9CRHUPRL7n9v0g@mail.gmail.com>
On Wed, Oct 22, 2014 at 02:51:56PM -0700, Andy Lutomirski wrote:
> On Wed, Oct 22, 2014 at 2:24 PM, Seth Forshee
> <seth.forshee@canonical.com> wrote:
> > Cc: Eric W. Biederman <ebiederm@xmission.com>
> > Cc: Serge H. Hallyn <serge.hallyn@ubuntu.com>
> > Cc: Andy Lutomirski <luto@amacapital.net>
> > Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
> > ---
> > fs/fuse/inode.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> > index b88b5a780228..7d0e73e36e7b 100644
> > --- a/fs/fuse/inode.c
> > +++ b/fs/fuse/inode.c
> > @@ -1201,7 +1201,7 @@ static void fuse_kill_sb_anon(struct super_block *sb)
> > static struct file_system_type fuse_fs_type = {
> > .owner = THIS_MODULE,
> > .name = "fuse",
> > - .fs_flags = FS_HAS_SUBTYPE,
> > + .fs_flags = FS_HAS_SUBTYPE | FS_USERNS_MOUNT,
> > .mount = fuse_mount,
> > .kill_sb = fuse_kill_sb_anon,
> > };
> > @@ -1233,7 +1233,7 @@ static struct file_system_type fuseblk_fs_type = {
> > .name = "fuseblk",
> > .mount = fuse_mount_blk,
> > .kill_sb = fuse_kill_sb_blk,
> > - .fs_flags = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
> > + .fs_flags = FS_REQUIRES_DEV | FS_HAS_SUBTYPE | FS_USERNS_MOUNT,
> > };
> > MODULE_ALIAS_FS("fuseblk");
> >
> > --
> > 1.9.1
> >
>
> This is mostly a sign of my ignorance, but how does this actually end
> up working? I assume that the mounter opens /dev/fuse and then passes
> the fd to the mount call. Which userns is captured? The opener of
> /dev/fuse or the mounter of the fs?
You're correct that the mounter passes the fd to /dev/fuse to the mount
call. The namespace of the mounter is used, but there's also a check to
make sure that's the same as that of the opener of /dev/fuse, otherwise
the mount fails.
Seth
next prev parent reply other threads:[~2014-10-23 0:22 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-22 21:24 [PATCH v5 0/4] fuse: Add support for mounts from pid/user namespaces Seth Forshee
2014-10-22 21:24 ` [PATCH v5 1/4] fuse: Add support for pid namespaces Seth Forshee
2014-11-11 13:27 ` Miklos Szeredi
2014-11-11 15:24 ` Seth Forshee
2014-11-11 15:39 ` Andy Lutomirski
2014-11-11 16:26 ` Seth Forshee
2014-11-12 12:07 ` Miklos Szeredi
2014-11-12 14:33 ` Seth Forshee
2014-10-22 21:24 ` [PATCH v5 2/4] fuse: Support fuse filesystems outside of init_user_ns Seth Forshee
2014-10-22 21:47 ` Andy Lutomirski
2014-11-11 14:04 ` Miklos Szeredi
2014-11-11 15:27 ` Seth Forshee
2014-11-11 15:37 ` Eric W. Biederman
2014-11-12 13:09 ` Miklos Szeredi
2014-11-12 16:22 ` Seth Forshee
2014-11-18 15:21 ` Seth Forshee
2014-11-18 17:09 ` Andy Lutomirski
2014-11-18 17:13 ` Seth Forshee
2014-11-18 17:19 ` Andy Lutomirski
2014-11-19 8:50 ` Miklos Szeredi
2014-11-19 10:38 ` Miklos Szeredi
2014-11-19 14:09 ` Serge E. Hallyn
2014-11-21 16:44 ` Seth Forshee
2014-11-21 17:19 ` Andy Lutomirski
2014-11-21 18:14 ` Eric W. Biederman
2014-11-21 18:25 ` Andy Lutomirski
2014-11-21 18:27 ` Seth Forshee
2014-11-21 18:38 ` Andy Lutomirski
2014-10-22 21:24 ` [PATCH v5 3/4] fuse: Restrict allow_other to the superblock's namespace or a descendant Seth Forshee
2014-10-22 21:48 ` Andy Lutomirski
2014-11-11 15:27 ` Miklos Szeredi
2014-11-11 15:37 ` Seth Forshee
2014-10-22 21:24 ` [PATCH v5 4/4] fuse: Allow user namespace mounts Seth Forshee
2014-10-22 21:51 ` Andy Lutomirski
2014-10-23 0:22 ` Seth Forshee [this message]
2014-10-23 2:19 ` Andy Lutomirski
2014-11-03 17:15 ` [PATCH v5 0/4] fuse: Add support for mounts from pid/user namespaces Seth Forshee
2014-11-03 17:17 ` Andy Lutomirski
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