Return-Path: Received: from mail-cys01nam02on0130.outbound.protection.outlook.com ([104.47.37.130]:16451 "EHLO NAM02-CY1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965970AbeCHFFP (ORCPT ); Thu, 8 Mar 2018 00:05:15 -0500 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: Masami Hiramatsu , Ananth N Mavinakayanahalli , Anil S Keshavamurthy , Borislav Petkov , Brian Gerst , "David S . Miller" , Denys Vlasenko , "H . Peter Anvin" , Josh Poimboeuf , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Ye Xiaolong , Ingo Molnar , Sasha Levin Subject: [PATCH AUTOSEL for 4.4 008/101] kprobes/x86: Set kprobes pages read-only Date: Thu, 8 Mar 2018 05:01:11 +0000 Message-ID: <20180308050023.8548-8-alexander.levin@microsoft.com> References: <20180308050023.8548-1-alexander.levin@microsoft.com> In-Reply-To: <20180308050023.8548-1-alexander.levin@microsoft.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: From: Masami Hiramatsu [ Upstream commit d0381c81c2f782fa2131178d11e0cfb23d50d631 ] Set the pages which is used for kprobes' singlestep buffer and optprobe's trampoline instruction buffer to readonly. This can prevent unexpected (or unintended) instruction modification. This also passes rodata_test as below. Without this patch, rodata_test shows a warning: WARNING: CPU: 0 PID: 1 at arch/x86/mm/dump_pagetables.c:235 note_page+0x7= a9/0xa20 x86/mm: Found insecure W+X mapping at address ffffffffa0000000/0xffffffff= a0000000 With this fix, no W+X pages are found: x86/mm: Checked W+X mappings: passed, no W+X pages found. rodata_test: all tests were successful Reported-by: Andrey Ryabinin Signed-off-by: Masami Hiramatsu Cc: Ananth N Mavinakayanahalli Cc: Anil S Keshavamurthy Cc: Borislav Petkov Cc: Brian Gerst Cc: David S . Miller Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ye Xiaolong Link: http://lkml.kernel.org/r/149076375592.22469.14174394514338612247.stgi= t@devbox Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- arch/x86/kernel/kprobes/core.c | 4 ++++ arch/x86/kernel/kprobes/opt.c | 3 +++ 2 files changed, 7 insertions(+) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.= c index 5d11d01f75de..565e24e9ddf2 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -406,6 +406,8 @@ static int arch_copy_kprobe(struct kprobe *p) { int ret; =20 + set_memory_rw((unsigned long)p->ainsn.insn & PAGE_MASK, 1); + /* Copy an instruction with recovering if other optprobe modifies it.*/ ret =3D __copy_instruction(p->ainsn.insn, p->addr); if (!ret) @@ -420,6 +422,8 @@ static int arch_copy_kprobe(struct kprobe *p) else p->ainsn.boostable =3D -1; =20 + set_memory_ro((unsigned long)p->ainsn.insn & PAGE_MASK, 1); + /* Check whether the instruction modifies Interrupt Flag or not */ p->ainsn.if_modifier =3D is_IF_modifier(p->ainsn.insn); =20 diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index ea8e2b846101..7aba9d6475a5 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -370,6 +370,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kpro= be *op, } =20 buf =3D (u8 *)op->optinsn.insn; + set_memory_rw((unsigned long)buf & PAGE_MASK, 1); =20 /* Copy instructions into the out-of-line buffer */ ret =3D copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr); @@ -392,6 +393,8 @@ int arch_prepare_optimized_kprobe(struct optimized_kpro= be *op, synthesize_reljump(buf + TMPL_END_IDX + op->optinsn.size, (u8 *)op->kp.addr + op->optinsn.size); =20 + set_memory_ro((unsigned long)buf & PAGE_MASK, 1); + flush_icache_range((unsigned long) buf, (unsigned long) buf + TMPL_END_IDX + op->optinsn.size + RELATIVEJUMP_SIZE); --=20 2.14.1