From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 1 Feb 2018 09:18:11 +0100 From: Greg KH To: Paul Moore , Mark Salyzyn Cc: Stephen Smalley , linux-kernel@vger.kernel.org, Eric Paris , James Morris , "Serge E. Hallyn" , selinux@tycho.nsa.gov, linux-security-module@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] general protection fault in sock_has_perm Message-ID: <20180201081811.GF15896@kroah.com> References: <20180118215853.228182-1-salyzyn@android.com> <1516382386.2560.11.camel@tycho.nsa.gov> <1516383672.2560.23.camel@tycho.nsa.gov> <99c11fa6-ad9a-830c-467e-6a56e78aecf8@android.com> <20180130224614.GA13647@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.3 (2018-01-21) X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Jan 31, 2018 at 04:06:37AM -0500, Paul Moore wrote: > On Tue, Jan 30, 2018 at 5:46 PM, Greg KH wrote: > > On Tue, Jan 30, 2018 at 11:00:04AM -0800, Mark Salyzyn wrote: > >> On 01/19/2018 09:41 AM, Stephen Smalley wrote: > >> > If we can't safely dereference the sock in these hooks, then that seems > >> > to point back to the approach used in my original code, where in > >> > ancient history I had sock_has_perm() take the socket and use its inode > >> > i_security field instead of the sock. commit > >> > 253bfae6e0ad97554799affa0266052968a45808 switched them to use the sock > >> > instead. > >> > >> Because of the nature of this problem (hard to duplicate, no clear path), I > >> am understandably not comfortable reverting and submitting for testing in > >> order to prove this point. It is disruptive because it changes several > >> subroutine call signatures. > >> > >> AFAIK this looks like a user request racing in without reference counting or > >> RCU grace period in the callers (could be viewed as not an issue with > >> security code). Effectively fixed in 4.9-stable, but broken in 4.4-stable. > >> > >> hygiene, KISS and small, is all I do feel comfortable to submit to > >> 4.4-stable without pulling in all the infrastructure improvements. > >> > >> -- Mark > >> > >> --- > >> security/selinux/hooks.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > >> index 34427384605d..be68992a28cb 100644 > >> --- a/security/selinux/hooks.c > >> +++ b/security/selinux/hooks.c > >> @@ -4066,6 +4066,8 @@ static int sock_has_perm(struct task_struct *task, > >> struct sock *sk, u32 perms) > >> struct lsm_network_audit net = {0,}; > >> u32 tsid = task_sid(task); > >> > >> + if (!sksec) > >> + return -EFAULT; > >> if (sksec->sid == SECINITSID_KERNEL) > >> return 0; > >> > > > > This looks sane to me as a simple 4.4-only fix. If the SELinux > > maintainer acks it, I can easily queue this up. > > This revision addresses my concerns with Mark's previous patch. > > Acked-by: Paul Moore Wonderful! Mark, can you resend this in a format I can apply it in? thanks, greg k-h From mboxrd@z Thu Jan 1 00:00:00 1970 From: gregkh@linuxfoundation.org (Greg KH) Date: Thu, 1 Feb 2018 09:18:11 +0100 Subject: [PATCH] general protection fault in sock_has_perm In-Reply-To: References: <20180118215853.228182-1-salyzyn@android.com> <1516382386.2560.11.camel@tycho.nsa.gov> <1516383672.2560.23.camel@tycho.nsa.gov> <99c11fa6-ad9a-830c-467e-6a56e78aecf8@android.com> <20180130224614.GA13647@kroah.com> Message-ID: <20180201081811.GF15896@kroah.com> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Wed, Jan 31, 2018 at 04:06:37AM -0500, Paul Moore wrote: > On Tue, Jan 30, 2018 at 5:46 PM, Greg KH wrote: > > On Tue, Jan 30, 2018 at 11:00:04AM -0800, Mark Salyzyn wrote: > >> On 01/19/2018 09:41 AM, Stephen Smalley wrote: > >> > If we can't safely dereference the sock in these hooks, then that seems > >> > to point back to the approach used in my original code, where in > >> > ancient history I had sock_has_perm() take the socket and use its inode > >> > i_security field instead of the sock. commit > >> > 253bfae6e0ad97554799affa0266052968a45808 switched them to use the sock > >> > instead. > >> > >> Because of the nature of this problem (hard to duplicate, no clear path), I > >> am understandably not comfortable reverting and submitting for testing in > >> order to prove this point. It is disruptive because it changes several > >> subroutine call signatures. > >> > >> AFAIK this looks like a user request racing in without reference counting or > >> RCU grace period in the callers (could be viewed as not an issue with > >> security code). Effectively fixed in 4.9-stable, but broken in 4.4-stable. > >> > >> hygiene, KISS and small, is all I do feel comfortable to submit to > >> 4.4-stable without pulling in all the infrastructure improvements. > >> > >> -- Mark > >> > >> --- > >> security/selinux/hooks.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > >> index 34427384605d..be68992a28cb 100644 > >> --- a/security/selinux/hooks.c > >> +++ b/security/selinux/hooks.c > >> @@ -4066,6 +4066,8 @@ static int sock_has_perm(struct task_struct *task, > >> struct sock *sk, u32 perms) > >> struct lsm_network_audit net = {0,}; > >> u32 tsid = task_sid(task); > >> > >> + if (!sksec) > >> + return -EFAULT; > >> if (sksec->sid == SECINITSID_KERNEL) > >> return 0; > >> > > > > This looks sane to me as a simple 4.4-only fix. If the SELinux > > maintainer acks it, I can easily queue this up. > > This revision addresses my concerns with Mark's previous patch. > > Acked-by: Paul Moore Wonderful! Mark, can you resend this in a format I can apply it in? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html