From: "J. Bruce Fields" Subject: Re: [PATCH] nfsd: nfsd should drop CAP_MKNOD for non-root Date: Wed, 18 Mar 2009 13:32:21 -0400 Message-ID: <20090318173221.GA16077@fieldses.org> References: <1237393292-14934-1-git-send-email-bfields@fieldses.org> <1237393292-14934-2-git-send-email-bfields@fieldses.org> <1237393292-14934-3-git-send-email-bfields@fieldses.org> <20090318170843.GA29045@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linus Torvalds , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Igor Zhbanov , stable@kernel.org To: "Serge E. Hallyn" Return-path: Received: from mail.fieldses.org ([141.211.133.115]:53955 "EHLO pickle.fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751533AbZCRRc1 (ORCPT ); Wed, 18 Mar 2009 13:32:27 -0400 In-Reply-To: <20090318170843.GA29045@us.ibm.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Mar 18, 2009 at 12:08:43PM -0500, Serge E. Hallyn wrote: > Quoting J. Bruce Fields (bfields@fieldses.org): > > From: J. Bruce Fields > > > > Since creating a device node is normally an operation requiring special > > privilege, Igor Zhbanov points out that it is surprising (to say the > > least) that a client can, for example, create a device node on a > > filesystem exported with root_squash. > > > > So, make sure CAP_MKNOD is among the capabilities dropped when an nfsd > > thread handles a request from a non-root user. > > > > Reported-by: Igor Zhbanov > > Cc: stable@kernel.org > > Signed-off-by: J. Bruce Fields > > Acked-by: Serge Hallyn > > I assume CAP_LINUX_IMMUTABLE simply does not apply to nfs? Right. We shouldn't care how it's set. > And, you're adding CAP_FS_MASK_B1 in anticipation of labeled nfs? That's unchanged (would have been clearer if I hadn't re-line-wrapped in the same patch). > Though, I was going to send a patch later today or tomorrow (figure I > should do some ltp testing) adding CAP_MKNOD to the whole > CAP_FS_MASK_B0 (and CAP_LINUX_IMMUTABLE and CAP_FS_MASK_B1 to > CAP_FS_SET). That will conflict with this one. OK, feel free to revert this at that point if necessary. --b. > > thanks, > -serge > > > --- > > include/linux/capability.h | 6 ++++-- > > 1 files changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/capability.h b/include/linux/capability.h > > index 1b98725..4864a43 100644 > > --- a/include/linux/capability.h > > +++ b/include/linux/capability.h > > @@ -393,8 +393,10 @@ struct cpu_vfs_cap_data { > > # define CAP_FULL_SET ((kernel_cap_t){{ ~0, ~0 }}) > > # define CAP_INIT_EFF_SET ((kernel_cap_t){{ ~CAP_TO_MASK(CAP_SETPCAP), ~0 }}) > > # define CAP_FS_SET ((kernel_cap_t){{ CAP_FS_MASK_B0, CAP_FS_MASK_B1 } }) > > -# define CAP_NFSD_SET ((kernel_cap_t){{ CAP_FS_MASK_B0|CAP_TO_MASK(CAP_SYS_RESOURCE), \ > > - CAP_FS_MASK_B1 } }) > > +# define CAP_NFSD_SET ((kernel_cap_t){{ CAP_FS_MASK_B0 \ > > + | CAP_TO_MASK(CAP_SYS_RESOURCE) \ > > + | CAP_TO_MASK(CAP_MKNOD), \ > > + CAP_FS_MASK_B1 } }) > > > > #endif /* _KERNEL_CAPABILITY_U32S != 2 */ > > > > -- > > 1.6.0.4