From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761814AbZCPXD4 (ORCPT ); Mon, 16 Mar 2009 19:03:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754977AbZCPXDr (ORCPT ); Mon, 16 Mar 2009 19:03:47 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:51194 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754488AbZCPXDq (ORCPT ); Mon, 16 Mar 2009 19:03:46 -0400 Date: Mon, 16 Mar 2009 18:03:42 -0500 From: "Serge E. Hallyn" To: "J. Bruce Fields" Cc: Stephen Smalley , Igor Zhbanov , Michael Kerrisk , linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, neilb@suse.de, Trond.Myklebust@netapp.com, David Howells , Andrew Morgan , James Morris , linux-security-module@vger.kernel.org, SELinux Subject: Re: =?utf-8?B?0J7RgtCy0LXRgjogVkZTLCBORlMg?= =?utf-8?Q?security_bug=3F_Shoul?= =?utf-8?Q?d?= CAP_MKNOD and CAP_LINUX_IMMUTABLE be added to CAP_FS_MASK? Message-ID: <20090316230342.GB15522@us.ibm.com> References: <20090311232356.GP13540@fieldses.org> <20090312161047.GA15209@us.ibm.com> <517f3f820903121321sf6d2014q8165b925d5d44db7@mail.gmail.com> <20090313175848.GB27891@fieldses.org> <20090313190002.GA16025@us.ibm.com> <1237227705.1035.93.camel@localhost.localdomain> <20090316184926.GA6729@us.ibm.com> <20090316224848.GC17738@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090316224848.GC17738@fieldses.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting J. Bruce Fields (bfields@fieldses.org): > Seems this isn't entirely obvious in the general case. In the specific I think the MKNOD part is (based on historical behavior as you suggested) obvious: both masks should include CAP_MKNOD and CAP_LINUX_IMMUTABLE. (references: http://lxr.linux.no/linux-old+v2.0.21/fs/ext2/ioctl.c#L60 for immutable and http://lxr.linux.no/linux-old+v2.0.21/fs/namei.c#L503 for mknod) -serge > case of nfsd, however, this is pretty obvious. So I'm inclined to > submit the following now (and leave it to be reverted by a later patch > if CAP_FS_MASK ends up including CAP_MKNOD, as seems likely). > > --b. > > commit 2ec8f8f0c0005ffe3cf93bbf3d9976de76cf4652 > Author: J. Bruce Fields > Date: Mon Mar 16 18:34:20 2009 -0400 > > nfsd: nfsd should drop CAP_MKNOD for non-root > > 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 > Signed-off-by: J. Bruce Fields > > diff --git a/include/linux/capability.h b/include/linux/capability.h > index 02bdb76..7824483 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 */ From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 16 Mar 2009 18:03:42 -0500 From: "Serge E. Hallyn" To: "J. Bruce Fields" Cc: Stephen Smalley , Igor Zhbanov , Michael Kerrisk , linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, neilb@suse.de, Trond.Myklebust@netapp.com, David Howells , Andrew Morgan , James Morris , linux-security-module@vger.kernel.org, SELinux Subject: Re: =?utf-8?B?0J7RgtCy0LXRgjogVkZTLCBORlMg?= =?utf-8?Q?security_bug=3F_Shoul?= =?utf-8?Q?d?= CAP_MKNOD and CAP_LINUX_IMMUTABLE be added to CAP_FS_MASK? Message-ID: <20090316230342.GB15522@us.ibm.com> References: <20090311232356.GP13540@fieldses.org> <20090312161047.GA15209@us.ibm.com> <517f3f820903121321sf6d2014q8165b925d5d44db7@mail.gmail.com> <20090313175848.GB27891@fieldses.org> <20090313190002.GA16025@us.ibm.com> <1237227705.1035.93.camel@localhost.localdomain> <20090316184926.GA6729@us.ibm.com> <20090316224848.GC17738@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20090316224848.GC17738@fieldses.org> Sender: owner-selinux@tycho.nsa.gov List-Id: selinux@tycho.nsa.gov Quoting J. Bruce Fields (bfields@fieldses.org): > Seems this isn't entirely obvious in the general case. In the specific I think the MKNOD part is (based on historical behavior as you suggested) obvious: both masks should include CAP_MKNOD and CAP_LINUX_IMMUTABLE. (references: http://lxr.linux.no/linux-old+v2.0.21/fs/ext2/ioctl.c#L60 for immutable and http://lxr.linux.no/linux-old+v2.0.21/fs/namei.c#L503 for mknod) -serge > case of nfsd, however, this is pretty obvious. So I'm inclined to > submit the following now (and leave it to be reverted by a later patch > if CAP_FS_MASK ends up including CAP_MKNOD, as seems likely). > > --b. > > commit 2ec8f8f0c0005ffe3cf93bbf3d9976de76cf4652 > Author: J. Bruce Fields > Date: Mon Mar 16 18:34:20 2009 -0400 > > nfsd: nfsd should drop CAP_MKNOD for non-root > > 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 > Signed-off-by: J. Bruce Fields > > diff --git a/include/linux/capability.h b/include/linux/capability.h > index 02bdb76..7824483 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 */ -- This message was distributed to subscribers of the selinux mailing list. If you no longer wish to subscribe, send mail to majordomo@tycho.nsa.gov with the words "unsubscribe selinux" without quotes as the message.