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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Sun, 28 Apr 2019 06:47:15 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3S5lE3355115962 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 28 Apr 2019 05:47:14 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A6EF311C04C; Sun, 28 Apr 2019 05:47:14 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7CB1D11C04A; Sun, 28 Apr 2019 05:47:13 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.8.112]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Sun, 28 Apr 2019 05:47:13 +0000 (GMT) Date: Sun, 28 Apr 2019 08:47:11 +0300 From: Mike Rapoport To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Alexandre Chartre , Andy Lutomirski , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Ingo Molnar , James Bottomley , Jonathan Adams , Kees Cook , Paul Turner , Thomas Gleixner , linux-mm@kvack.org, linux-security-module@vger.kernel.org, x86@kernel.org Subject: Re: [RFC PATCH 5/7] x86/mm/fault: hook up SCI verification References: <1556228754-12996-1-git-send-email-rppt@linux.ibm.com> <1556228754-12996-6-git-send-email-rppt@linux.ibm.com> <20190426074223.GY4038@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190426074223.GY4038@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 19042805-0012-0000-0000-000003160447 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19042805-0013-0000-0000-0000214E65F8 Message-Id: <20190428054711.GD14896@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-28_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=374 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904280040 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Fri, Apr 26, 2019 at 09:42:23AM +0200, Peter Zijlstra wrote: > On Fri, Apr 26, 2019 at 12:45:52AM +0300, Mike Rapoport wrote: > > If a system call runs in isolated context, it's accesses to kernel code and > > data will be verified by SCI susbsytem. > > > > Signed-off-by: Mike Rapoport > > --- > > arch/x86/mm/fault.c | 28 ++++++++++++++++++++++++++++ > > 1 file changed, 28 insertions(+) > > There's a distinct lack of touching do_double_fault(). It appears to me > that you'll instantly trigger #DF when you #PF, because the #PF handler > itself will not be able to run. The #PF handler is able to run. On interrupt/error entry the cr3 is switched to the full kernel page tables, pretty much like PTI does for user <-> kernel transitions. It's in the patch 3. > And then obviously you have to be very careful to make sure #DF can, > _at_all_times_ run, otherwise you'll tripple-fault and we all know what > that does. > -- Sincerely yours, Mike.