linux-kernel - [tip:mm/pkeys] x86/pkeys: Add fault handling for PF

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 9 Sep 2016 04:10:39 -0700
From:   tip-bot for Dave Hansen <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     dave@...1.net, linux-kernel@...r.kernel.org, hpa@...or.com,
        mingo@...nel.org, dave.hansen@...ux.intel.com,
        mgorman@...hsingularity.net, tglx@...utronix.de
Subject: [tip:mm/pkeys] x86/pkeys: Add fault handling for PF_PK page fault
 bit

Commit-ID:  e8c6226d483cb28f55cab718065ea1b7226d40e8
Gitweb:     http://git.kernel.org/tip/e8c6226d483cb28f55cab718065ea1b7226d40e8
Author:     Dave Hansen <dave.hansen@...ux.intel.com>
AuthorDate: Fri, 29 Jul 2016 09:30:10 -0700
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 9 Sep 2016 13:02:26 +0200

x86/pkeys: Add fault handling for PF_PK page fault bit

PF_PK means that a memory access violated the protection key
access restrictions.  It is unconditionally an access_error()
because the permissions set on the VMA don't matter (the PKRU
value overrides it), and we never "resolve" PK faults (like
how a COW can "resolve write fault).

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Acked-by: Mel Gorman <mgorman@...hsingularity.net>
Cc: linux-arch@...r.kernel.org
Cc: Dave Hansen <dave@...1.net>
Cc: arnd@...db.de
Cc: linux-api@...r.kernel.org
Cc: linux-mm@...ck.org
Cc: luto@...nel.org
Cc: akpm@...ux-foundation.org
Cc: torvalds@...ux-foundation.org
Link: http://lkml.kernel.org/r/20160729163010.DD1FE1ED@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 arch/x86/mm/fault.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index dc80230..b88d8ac 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1112,6 +1112,15 @@ access_error(unsigned long error_code, struct vm_area_struct *vma)
 {
 	/* This is only called for the current mm, so: */
 	bool foreign = false;
+
+	/*
+	 * Read or write was blocked by protection keys.  This is
+	 * always an unconditional error and can never result in
+	 * a follow-up action to resolve the fault, like a COW.
+	 */
+	if (error_code & PF_PK)
+		return 1;
+
 	/*
 	 * Make sure to check the VMA so that we do not perform
 	 * faults just to hit a PF_PK as soon as we fill in a