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From: Kees Cook <keescook@chromium.org>
To: kernel-hardening@lists.openwall.com
Cc: Kees Cook <keescook@chromium.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Andy Lutomirski <luto@kernel.org>,
	Hoeun Ryu <hoeun.ryu@gmail.com>, PaX Team <pageexec@freemail.hu>,
	Emese Revfy <re.emese@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap()
Date: Wed, 29 Mar 2017 11:15:56 -0700
Message-ID: <1490811363-93944-5-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1490811363-93944-1-git-send-email-keescook@chromium.org>

Based on PaX's x86 pax_{open,close}_kernel() implementation, this
allows HAVE_ARCH_RARE_WRITE to work on x86.

There is missing work to sort out some header file issues where preempt.h
is missing, though it can't be included in pg_table.h unconditionally...
some other solution will be needed, perhaps an entirely separate header
file for rare_write()-related defines...

This patch is also missing paravirt support.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/x86/Kconfig               |  1 +
 arch/x86/include/asm/pgtable.h | 31 +++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cc98d5a294ee..2d1d707aa036 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -106,6 +106,7 @@ config X86
 	select HAVE_ARCH_KMEMCHECK
 	select HAVE_ARCH_MMAP_RND_BITS		if MMU
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
+	select HAVE_ARCH_RARE_WRITE
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 1cfb36b8c024..2e6bf661bb84 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -91,6 +91,37 @@ extern struct mm_struct *pgd_page_get_mm(struct page *page);
 
 #endif	/* CONFIG_PARAVIRT */
 
+/* TODO: Bad hack to deal with preempt macros being missing sometimes. */
+#ifndef preempt_disable
+#include <linux/preempt.h>
+#endif
+
+static __always_inline unsigned long __arch_rare_write_begin(void)
+{
+	unsigned long cr0;
+
+	preempt_disable();
+	barrier();
+	cr0 = read_cr0() ^ X86_CR0_WP;
+	BUG_ON(cr0 & X86_CR0_WP);
+	write_cr0(cr0);
+	barrier();
+	return cr0 ^ X86_CR0_WP;
+}
+
+static __always_inline unsigned long __arch_rare_write_end(void)
+{
+	unsigned long cr0;
+
+	barrier();
+	cr0 = read_cr0() ^ X86_CR0_WP;
+	BUG_ON(!(cr0 & X86_CR0_WP));
+	write_cr0(cr0);
+	barrier();
+	preempt_enable_no_resched();
+	return cr0 ^ X86_CR0_WP;
+}
+
 /*
  * The following only work if pte_present() is true.
  * Undefined behaviour if not..
-- 
2.7.4

  parent reply index

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-29 18:15 [RFC v2] Introduce rare_write() infrastructure Kees Cook
2017-03-29 18:15 ` [RFC v2][PATCH 01/11] " Kees Cook
2017-03-29 18:23   ` Kees Cook
2017-03-30  7:44     ` Ho-Eun Ryu
2017-03-30 17:02       ` Kees Cook
2017-04-07  8:09   ` Ho-Eun Ryu
2017-04-07 20:38     ` Kees Cook
2017-03-29 18:15 ` [RFC v2][PATCH 02/11] lkdtm: add test for " Kees Cook
2017-03-30  9:34   ` [kernel-hardening] " Ian Campbell
2017-03-30 16:16     ` Kees Cook
2017-03-29 18:15 ` [RFC v2][PATCH 03/11] net: switch sock_diag handlers to rare_write() Kees Cook
2017-03-29 18:15 ` Kees Cook [this message]
2017-03-29 22:38   ` [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Andy Lutomirski
2017-03-30  1:41     ` Kees Cook
2017-04-05 23:57       ` Andy Lutomirski
2017-04-06  0:14         ` Kees Cook
2017-04-06 15:59           ` Andy Lutomirski
2017-04-07  8:34             ` [kernel-hardening] " Mathias Krause
2017-04-07  9:46               ` Thomas Gleixner
2017-04-07 10:51                 ` Mathias Krause
2017-04-07 13:14                   ` Thomas Gleixner
2017-04-07 13:30                     ` Mathias Krause
2017-04-07 16:14                       ` Andy Lutomirski
2017-04-07 16:22                         ` Mark Rutland
2017-04-07 19:58                         ` PaX Team
2017-04-08  4:58                           ` Andy Lutomirski
2017-04-09 12:47                             ` PaX Team
2017-04-10  0:10                               ` Andy Lutomirski
2017-04-10 10:42                                 ` PaX Team
2017-04-10 16:01                                   ` Andy Lutomirski
2017-04-07 20:44                         ` Thomas Gleixner
2017-04-07 21:20                           ` Kees Cook
2017-04-08  4:12                             ` Daniel Micay
2017-04-08  4:13                               ` Daniel Micay
2017-04-08  4:21                         ` Daniel Micay
2017-04-08  5:07                           ` Andy Lutomirski
2017-04-08  7:33                             ` Daniel Micay
2017-04-08 15:20                               ` Andy Lutomirski
2017-04-09 10:53                                 ` Ingo Molnar
2017-04-10 10:22                                 ` Mark Rutland
2017-04-09 20:24                             ` PaX Team
2017-04-10  0:31                               ` Andy Lutomirski
2017-04-10 19:47                                 ` PaX Team
2017-04-10 20:27                                   ` Andy Lutomirski
2017-04-10 20:13                               ` Kees Cook
2017-04-10 20:17                                 ` Andy Lutomirski
2017-04-07 19:25                       ` Thomas Gleixner
2017-04-07 14:45                   ` Peter Zijlstra
2017-04-10 10:29                     ` Mark Rutland
2017-04-07 19:52                 ` PaX Team
2017-04-10  8:26                   ` Thomas Gleixner
2017-04-10 19:55                     ` PaX Team
2017-04-07  9:37   ` Peter Zijlstra
2017-03-29 18:15 ` [RFC v2][PATCH 05/11] ARM: mm: dump: Add domain to output Kees Cook
2017-03-29 18:15 ` [RFC v2][PATCH 06/11] ARM: domains: Extract common USER domain init Kees Cook
2017-03-29 18:15 ` [RFC v2][PATCH 07/11] ARM: mm: set DOMAIN_WR_RARE for rodata Kees Cook
2017-03-29 18:16 ` [RFC v2][PATCH 08/11] ARM: Implement __arch_rare_write_begin/end() Kees Cook
2017-04-07  9:36   ` Peter Zijlstra
2017-03-29 18:16 ` [RFC v2][PATCH 09/11] list: add rare_write() list helpers Kees Cook
2017-03-29 18:16 ` [RFC v2][PATCH 10/11] gcc-plugins: Add constify plugin Kees Cook
2017-03-29 18:16 ` [RFC v2][PATCH 11/11] cgroups: force all struct cftype const Kees Cook
2017-03-29 19:00 ` [RFC v2] Introduce rare_write() infrastructure Russell King - ARM Linux
2017-03-29 19:14   ` Kees Cook

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