LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "Serge E. Hallyn" <serue@us.ibm.com>
To: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>,
	Andrew Morton <akpm@osdl.org>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -mm 7/8] user_ns: handle file sigio
Date: Mon, 15 Jan 2007 09:28:25 -0600	[thread overview]
Message-ID: <20070115152825.GA20350@sergelap.austin.ibm.com> (raw)
In-Reply-To: <45AB97D5.6010503@fr.ibm.com>

Quoting Cedric Le Goater (clg@fr.ibm.com):
> Serge E. Hallyn wrote:
> > Quoting Andrew Morton (akpm@osdl.org):
> >> On Thu, 4 Jan 2007 12:12:57 -0600
> >> "Serge E. Hallyn" <serue@us.ibm.com> wrote:
> >>
> >>> A process in one user namespace could set a fowner and sigio on a file in a
> >>> shared vfsmount, ending up killing a task in another user namespace.
> >>>
> >>> Prevent this by adding a user namespace pointer to the fown_struct, and
> >>> enforcing that a process causing a signal to be sent be in the same
> >>> user namespace as the file owner.
> >> This patch breaks the X server (stock FC5 install) with CONFIG_USER_NS=n.
> >> Neither the USB mouse nor the trackpad work.  They work OK under GPM.
> >>
> >> Setting CONFIG_USER_NS=y "fixes" this.  This bug was not observed in
> >> 2.6.20-rc3-mm1 because that kernel had user-ns-always-on.patch for other
> >> reasons.  (I'll restore that patch).
> >>
> >> There's nothing very interesting here:
> >
> [ ... ]
> >
> > I can't see any reason for this in the code or comparative ltp runs.
> > Cedric is testing on a fc6 laptop, hopefully he can reproduce it.
> 
> I did reproduce it on a FC5 desktop finally.
> 
> get_user_ns() returns NULL when CONFIG_USER_NS=n and this breaks
> sigio_perm() which does not expect NULL values for ->user_ns.

Argh.

Thanks, Cedric.

Rewriting the userns testcases right now.  Clearly, in addition to
separately testing clone and unshare, I need to add a sigioperm check,
and have a separate set of testcases for CONFIG_USER_NS=n.

thanks,
-serge

> I would fix this with the following patch.
> 
> C.
> 
> 
> Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>

Acked-off-by: Serge E Hallyn <serue@us.ibm.com>

> ---
>  include/linux/user_namespace.h |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: 2.6.20-rc4-mm1/include/linux/user_namespace.h
> ===================================================================
> --- 2.6.20-rc4-mm1.orig/include/linux/user_namespace.h
> +++ 2.6.20-rc4-mm1/include/linux/user_namespace.h
> @@ -49,7 +49,7 @@
> 
>  static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
>  {
> -	return NULL;
> +	return &init_user_ns;
>  }
> 
>  static inline int unshare_user_ns(unsigned long flags,

  reply	other threads:[~2007-01-15 15:28 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-04 18:06 [PATCH -mm 0/8] user ns: Introduction Serge E. Hallyn
2007-01-04 18:10 ` [PATCH -mm 1/8] nsproxy: externalizes exit_task_namespaces Serge E. Hallyn
2007-01-04 18:11 ` [PATCH -mm 2/8] user namespace: add the framework Serge E. Hallyn
2007-01-04 21:16   ` Serge E. Hallyn
2007-01-04 18:11 ` [PATCH -mm 3/8] user ns: add user_namespace ptr to vfsmount Serge E. Hallyn
2007-01-04 18:11 ` [PATCH -mm 4/8] user ns: hook permission Serge E. Hallyn
2007-01-04 18:12 ` [PATCH -mm 5/8] user ns: prepare copy_tree, copy_mnt, and their callers to handle errs Serge E. Hallyn
2007-01-04 19:00   ` Frederik Deweerdt
2007-01-04 19:35     ` Serge E. Hallyn
2007-01-04 18:12 ` [PATCH -mm 6/8] user ns: implement shared mounts Serge E. Hallyn
2007-01-04 18:12 ` [PATCH -mm 7/8] user_ns: handle file sigio Serge E. Hallyn
2007-01-12  5:20   ` Andrew Morton
2007-01-15  7:26     ` Serge E. Hallyn
2007-01-15 15:03       ` Cedric Le Goater
2007-01-15 15:28         ` Serge E. Hallyn [this message]
2007-01-15 17:35           ` Cedric Le Goater
2007-01-16 11:04             ` [PATCH -mm] user_ns: remove CONFIG_USER_NS Cedric Le Goater
2007-01-16 14:53               ` Serge E. Hallyn
2007-01-04 18:13 ` [PATCH -mm 8/8] user ns: implement user ns unshare Serge E. Hallyn
2007-01-04 19:07   ` Frederik Deweerdt
2007-01-04 19:43     ` Serge E. Hallyn
2007-01-04 22:03       ` Andrew Morton
2007-01-04 22:07         ` Andrew Morton
2007-01-04 22:23     ` Valdis.Kletnieks
2007-01-04 22:52       ` Serge E. Hallyn
2007-01-05  2:02         ` Valdis.Kletnieks
2007-01-05  4:35           ` Serge E. Hallyn
2007-01-05  4:03 ` [PATCH -mm 0/8] user ns: Introduction Andrew Morton
2007-01-05  5:43   ` Serge E. Hallyn
2007-01-05  7:00     ` Serge E. Hallyn

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20070115152825.GA20350@sergelap.austin.ibm.com \
    --to=serue@us.ibm.com \
    --cc=akpm@osdl.org \
    --cc=clg@fr.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: [PATCH -mm 7/8] user_ns: handle file sigio' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).